한국정보디스플레이학회:학술대회논문집
The Korean Infomation Display Society (KIDS)
- Annual
Domain
- Electricity/Electronics > Display
2009.10a
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Recently, the FPD industry has faced the limit in market growth due to lack of new growth engine as a replacement of television. With sluggish market demand deepened by global economic crisis and persistent concern over panel oversupply, growth of the panel market has sharply slowed down, and profitability has been eroded. This also has tremendous effect on related industries including component, material and machine industries, spreading a sense of crisis across the whole FPD industry. Under this circumstance, for the FPD industry to take off once again, all involved in the FPD industry must cooperate and come up with innovative ideas, and identify the driving force to realize turbo-charged growth.
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This presentation reviews the current progress in the technology of Light Emitting Diode (LED) as it relates to the LED backlight for Liquid Crystal Display (LCD). A vivid description is given about the performance of LED that is still on the rise and certain limitations of LED that is on the decline.
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This presentation will introduce Merck's investments for business to support the future market growth as "trendsetter contributor". As the world's oldest phamaceutical & chemical company, Merck has made the seamless investment for innovation. The investment for the new technologies is being continued for new LC materials, OLED material, organic electronic materials for flexible display, more environment friendly products of cell Etching Solutions to Solar Cell makers and variety of high-efficiency phosphors for LED applications. These investment portfolio is well in line with future business environment driving for eco-friendly, thin, fast, low power consumption."
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Takezoe, Hideo;Gomola, Kinga;Guo, Lingfeng;Dhara, Surajit;Shimbo, Yoshio;Gorecka, Ewa;Pociecha, Damian;Mieczkowski, Jozef 8
After reviewing the principle of a new display utilizing bent-core liquid crystals, we summarize the advantages and problems of this display. Then we will introduce our effort to overcome these problems mostly by synthesizing new materials. We obtained a variety of newly synthesized compounds showing the$SmAP_R$ phase. Mixing was effective to decrease and widening the temperature range of the$SmAP_R$ phase. -
We have developed variety of LCD technologies for the out-door display, which improve out-door readability as well as reliability from external impacts. This improvement was made possible by new approach on LCD cell optical design and modification of LCD surface, which allows surrounding light to be transmitted to enhance the visibility and at the same time filtering out light, which are considered to be source of noise in terms of visibility. This technology enables users to maintain high display performance in both in-door & out-door environments moreover alternatively choosing in-door/out-door.
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Surface driven switching of the liquid crystal bulk arising from the coupling between an applied electric field and a polarized state of a nematic liquid crystal, both localized at the substrate surface, is reported. Fast switching is demonstrated in a hybrid aligned nematic cell with a fringe electric field generated by comb-like electrode structure.
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The voltage and frequency dependence of voltage holding ratio (VHR) in a homogeneously-aligned liquid-crystal (LC) cell is studied in this paper. The discharge curves with different scan frequencies are obtained and the saturation phenomenon of VHR is observed under specific amplitudes of driving voltage. Our results suggest a reasonable concept to improve the VHR in LC displays without increasing the frame rate.
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The efficacy improvement issues in a unit discharge cell have been approached from the structural considerations. The tested cell designs include (a) a coplanar type with annular auxiliary electrode buried in barrier ribs, (b) a coplanar type with split auxiliary electrodes also burred in barrier ribs and (c) a coaxial type with a floating electrode stacked on the base electrode. From spatiotemporally resolved optical images of near-IR emission taken by a gated-ICCD camera and relative VUV emission intensity estimated by laser absorption spectroscopy, the differences in the discharge and light emission performances of those three cell types have been compared and discussed.
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A hybrid model has been developed which adopts a fluid model for electrons and a particle-in-cell (PIC) model for ions. Using the hybrid simulation, the discharge characteristics are investigated with the diagnostics for the electric field and the wall charge profile, density distributions of charged and excited particles, distributions of ultraviolet lights on phosphor, and the visible lights emitted from the PDP cell. Also, energy and angle distributions of the ions at the MgO protective layer are obtained for the analysis of material effect. The comparison of hybrid simulation results with experimental results as well as that with the conventional fluid simulation shows that the new model is more adequate for the simulation of PDP cells.
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PDP panels with MgO protective layer are manufactured by using the "all-in-vacuum" process we have established [1]. This is the process aiming to keep the MgO surface as clean as possible after the evaporation. The panels are evaluated in term of discharge voltage, aging time, luminance, luminous efficacy, discharge time-lag. It is confirmed that the "all-in-vacuum" process particularly improves the aging time, discharge voltage and the discharge time-lag.
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Moon, Won-Seok;Oh, Jin-Mok;Seo, Byung-Hwa;Lee, Sung-Wook;Byun, Na-Mi;Cho, Yun-Hui;Ryu, Byung-Gil;Kim, Sung-Tae 31
We investigated the effect of relative dielectric constant of front dielectric layer on the efficacy of plasma display panel. Dielectric materials with relative dielectric constant of around 6 and 7 were developed. When the front dielectric layer had a low relative dielectric constant, power consumption decreased more than luminance did. And it led to efficacy enhancement. However, the minimum sustain voltage increased. -
In this work, we introduce new next generation activematrix backplane technologies for large-size AMOLED displays. Among the general requirements for successful market launch of AMOLED TVs, backplane issues are discussed. It will be shown that the amorphous oxide TFT is most suitable due to large scalability and superior cost effectiveness. Development status and current challenges of amorphous oxide TFTs are discussed.
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Weaver, Michael S.;Adamovich, Vadim I.;Xia, Sean C.;Fiordeliso, James J.;Kwong, Raymond C.;Brown, Julie J.;Lee, Kwan-Hee;Lim, Choon-Woo;Kim, Sung-Chul 38
We demonstrate a new commercial green phosphorescent organic light emitting device (OLED) in a bottom emission device and top emission microcavity. The bottom and top emitting phosphorescent OLEDs (PHOLED$^{TM}$ s) had luminance efficiencies of 60cd/A and 137cd/A respectively, at a luminance of 1,000cd/$m^2$ . The top emission microcavity was close to 1953 NTSC color requirements with 1931 CIE color coordinates of 0.231, 0.718. A record green PHOLED lifetime of >3,500hrs to LT95 from 4000cd/$m^2$ is demonstrated for the microcavity device. -
We report simple structure red phosphorescent devices comprising only single organic layer structure. Maximum current efficiency of 9.44 cd/A and the driving voltage of 5.4 V are obtained in this single layer structure PHOLEDs, respectively. The mixed host system using electron transporting and hole transporting materials doped with
$Ir(piq)_3$ provides such high efficiency and reasonable driving voltage. The principal to simplification is the direct charges injection from the metallic electrodes into mixed host materials. -
Seo, Ji-Hyun;Jin, You-Young;Kim, Hoe-Min;Choi, Eun-Young;Kim, Jun-Ho;Lee, Kum-Hee;Yoon, Seung-Soo;Kim, Young-Kwan 46
We demonstrated that the simple layered red phosphorescent organic light-emitting diodes are possible to have high efficiency and low driving voltage without hole injection and transport layers. The simplified OLED shows the max. current efficiency, power efficiency and quantum efficiency of 26.3 cd/A, 20.7 lm/W and 16.7 %, respectively. -
Phosphors with oxide host material, YAG:
$Ce^{3+}$ and$(Ca,Sr,Ba)_2SiO_4:Eu^{2+}$ yellow phosphor, has been used for LED applications. The WLEDs using these phosphors are widely used for LCD backlighting, automobile, and general lighting applications since they have high conversion efficiency and good thermal and chemical stability which can meet necessary life time of LED products up to now. With advances of LED chip technology, the external quantum efficiency and driving current in chip get higher so that the phosphors for high power chip are required to maintain high conversion efficiency and stability at high temperature due to the heat dissipated from LED chips. In addition, higher color rendering index of LED lighting and color reproducibility of LCD than those of LEDs with single yellow phosphors are required. In order to overcome these technical issues rising from evolution of LED technology, new phosphors are in demand and nitride phosphors, one of the promising new candidate materials, will be discussed here. -
Nitride Phosphors have recently been considered as a novel class of luminescent materials for white LEDs due to their promising luminescent properties. It is of great importance to tailor the emission color in order to meet the requirements for practical applications. The paper presents the results of tuning the emission colors of sialon phosphors through compositional tailoring.
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A red phosphor,
$(Sr,Ca)_2P_2O_7:Eu^{2+},Mn^{2+}$ , for UV-LED was synthesized under a reducing atmosphere, and its luminescent properties were investigated. The phosphor absorbs ultraviolet light at around 400 nm and efficiently emits red light at approximately 610 nm through an energy transfer from$Eu^{2+}$ to$Mn^{2+}$ . Using the varied input current test for the phosphor-loaded LED lamps, it was found that the luminescent efficiency of the phosphor decreased with increasing light flux. This might be due to an increased probability of excited-state absorption and the consequent non-radiative relaxation in$Mn^{2+}$ ions in the condition of high photon influx. -
In the nineties the invention of the InGaN blue LED has innovated illumination technology. Currently LCD backlighting and more and more general lighting applications are based on white LEDs comprising of inorganic phosphors and blue emitting InGaN chip. Well established phosphor materials are ortho silicates and garnets like yellow emitting YAG:Ce. In our paper we demonstrate that garnet materials also allow for green light emission for both, general lighting and backlighting LED applications.
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In this letter we report on the carrier velocity of polycrystalline pentacene transistors as a function of electric field. We performed a series of measurements on devices with a range of channel lengths. At moderate electric fields (<
$5{\times}10^5$ V/cm), the characteristics are similar to those of disordered or amorphous organic semiconductors. The highest velocities we have measured are near$6{\times}10^4$ cm/s at room temperature. We perform quasi-static and dynamic measurements to measure carrier velocity. These results fill an important void between experimental results that have been obtained with disordered/amorphous organic semiconductors and single crystals. -
We obtained high performance of n-type organic thin film transistors (OTFTs) using a solution process. N, N' bis-(octyl-)-dicyanoperylene-3,4:9,10-bis(dicarboximide) (PDI-
$8CN_2$ ) in ambient air. Low work function interlayer on source/drain is needed to enhance the electron injection to low LUMO level of n-type organic semiconductor. By using self-assembled monolayer (SAM) the field-effect mobility of 0.33$cm^2$ /Vs was achieved. -
Printed electronics are emerging technology to realize various microelectronic devices via a cost-effective method. Here we introduce high performance inkjet printed polymer field-effect transistors and application to complementary integrated circuits with p-type and n-type conjugated polymers. The performance of devices highly depends on the selection of dielectrics, printing condition and device architecture. The device optimization and performances of various integrated circuits, e.g., complementary inverters and ring oscillators will be mainly discussed in this talk.
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Recently several LCD TV makers including Samsung, LG and Sony actively have released LED LCD TV models on market. LED LCD TV is just which applied LED BLUs so that its color contrast ratio fairly enhance up to 1 million:1 and its thickness minimize to a few mm. Even this aspect seems somewhat to be each panel maker's strategies for prior market occupations on whole TV market. Without regard to the reasons, we do obviously meet a new era of technically advanced LCD TV. However we have still lots of problems or issues which we must overcome technically including LED chip/packaging process, secondary optics treatment, heat managements and cost reduction issues. Here I would like to forecast market volume and trend of LED LCD TV first and then discuss above almost of technical issues and suggest their possible solutions. Even these solutions looks better technologies and if they may increase production cost significantly, we will not prefer to choice that technology since lower cost policy can open the market. Finally I'm trying to suggest how well LED, as future light source, can apply to future LCD TV technologies.
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In this paper, we have designed a novel lens for LED's package that can expend the radiation angle of LED from
$120^{\circ}$ to$170^{\circ}$ successfully. At the same brightness and uniformity condition of 37" LED BLU system, using novel lens LED package can be reduced amounts of LED 40% or thickness of BLU 30% respectively. Besides, the power consumption of BLU also can be reduced 25%. -
A liquid crystal display that does not use color filters is proposed. A backlight unit that employs compartmentalized RGB LED arrays and a lenticular lens array is used instead of the color filters in order to direct RGB LED lights into the RGB subpixels. A design of color-filterless LED backlight and experimental results are presented.
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This work presents a novel lighting technology based on a YAG:
$Ce^{3+}$ phosphor converter with micro line lenticular structure, to accompany an array of bare LED chips on a board. This technology is especially effective in TFT-LCD backlight applications as it offers the advantages of high light radiation efficiency, low color deviation, uniform luminance distribution and compact backlight thickness. Additionally, the proposed configuration is low-cost, can be manufactured quickly, and can be mass-produced economically. -
Angele, Jacques;Joly, Stephane;Martinot-Lagarde, Philippe;Faget, Luc;Osterman, Jesper;Scheffer, Terry;Leblanc, Francois 83
BiNem$^{(R)}$ displays have entered volume manufacturing in 2009. Applications range from e-labels to e-readers. We have developed 6-inch$960{\times}720$ pixels passive matrix BiNem prototypes achieving 40 % brightness and fluid user interface based on partial image / dynamic pointer addressing. Active-matrix addressing is proposed to provide even faster operation. -
A dual-cell-gap transflective liquid crystal display (TR-LCD) with identical response time in the transmissive and reflective regions is demonstrated. In the transmissive region, strong anchoring energy condition is used to decrease the response time, while in the reflective region weak anchoring energy condition is used to increase the response time. The simulated dual-cell-gap TR-LCD has good performances.
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We propose advanced liquid crystal display (LCD) modes through surface modification using UV curable reactive mesogen (RM) mixed with alignment layers. The LC directors on the modified alignment layer are controlled and memorized by the polymerized RMs under an applied voltage. Using the method proposed here, we can improve the response time and viewing angle characteristics through surface controlled patterned vertical alignment (SC-PVA) mode and 8-domains PVA mode, respectively. Also, we found that the method can be applicable to fabricate multi-domain structures using multiple UV exposure as same as conventional UV alignment method.
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Lee, Ho-Jun;Jang, Jin-Ho;Kang, Kyoung-Il;Kim, Dong-Hyun;Park, Chung-Hoo;Kim, Jae-Sung;Jeon, Woo-Gon 95
It is analyzed how the Plasma - MgO surface interaction, driving waveform and their inter-relation can cause misfiring. Developing of glow discharge mode during the ramp reset due to lack of priming particles was suggested as one of the important misfiring sources. It is also shown that simple modification of reset waveform can considerably reduce misfiring probability. -
A negative waveform was studied to improve the driving characteristics of reset and address periods in ac PDP. Comparative experiments between negative and conventional positive waveforms were performed with 42-inch XGA PDP module. The negative waveform showed lower breakdown voltage than the conventional positive waveform in reset period. Due to its weak and stable discharge during reset period, the contrast ratio was improved by decreasing the black luminance. During address period, the discharge time-lag was measured. The formative time lag (
$=T_f$ ) of negative waveform was improved about 22.8% than$T_f$ of conventional positive waveform. -
Minimizing the residual impurity level on the MgO layer is the key factor for reducing temporal dark image sticking on bright screen. In this paper, to reduce the residual impurity level on the MgO layer of 50-in. full-HD ac-PDP with He (35%) - Xe (11%) contents, RF-plasma treatments on the MgO layer are adopted under various gases for plasma treatment. As a result of monitoring the difference in the display luminance between the before and after 5-min. sustain discharge with a square-type image at peak luminance, the Ar and Ar>
$O_2$ plasma treatments can reduce the temporal dark image sticking on the bright screen in an ac-PDP. -
Cho, Hyun-Min;Kim, Dong-Hwan;Song, In-Cheol;Kim, Yun-Gi;Ok, Jung-Woo;Kim, Dong-Hyun;Lee, Hae-June;Lee, Ho-Jun;Park, Chung-Hoo 104
In order to improve discharge characteristics in AC PDP, we suggest FDFA (Facing Discharge Front plate Address Electrode) structure. By adopting both long facing discharge electrodes and address electrodes in front plate, the FDFA structure make it possible to gain a high luminance, low power consumption, and a high luminous efficiency. -
We have determined the electronic energy level alignment at the interface between 4,4'-bis-N-phenyl-1-naphthylamino biphenyl (NPB) and 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HAT-CN) using ultraviolet photoelectron spectroscopy (UPS). The highest occupied molecular orbital (HOMO) of 20 nm thick HAT-CN film was located at 3.8 eV below the Fermi level. Thus the lowest unoccupied molecular orbital (LUMO) is very close to the Fermi level. The HOMO position of NPB was only about 0.3 eV below Fermi level at NPB/HAT-CN interface. This enables an easy excitation of electrons from the NPB HOMO to the HAT-CN LUMO, creating electron-hole pairs across this organic-organic interface. We also study the interaction of HAT-CN with a few metallic surfaces including Ca, Cu, and ITO using UPS and ab-inito electronic structure calculation techniques.
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Charge injection at electrode-organic interfaces is key to the performance, lifetime and stability of organic electronic devices. The link between fundamental material properties and the energy-level alignment at electrode-organic interfaces will be discussed. In addition the impact of the injection barrier height-a parameterization of the energylevel alignment-on device characteristics will also be discussed.
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Interface dipole energies between interfacial layers with different thicknesses coated on indium tin oxides (ITOs) and 4,4'-bis[N-(1-naphtyl)-N-phenyl-amino]biphenyl are determined. After
$O_2$ plasma treatment on thick-metal (>4 nm) coated ITO, the work function and interface dipole energy increased. In thin-metal (< 2 nm) coated ITO, no change in the interface dipole energy was found though the work function increased. Thus, the$O_2$ plasma treated thin (< 2 nm) interfacial layer reduced the hole injection barrier. -
We reported that the evidence of oxygen doping to copper-phthalocyanine (CuPc) by
$O_2$ -plasma treatment to Au electrode of inverted top emitting organic light emitting diodes (ITOLEDs). The operation voltage of OLEDs at 150 mA/$cm^2$ decreased from 16.1 to 10.3 V as oxygen atoms indiffued to CuPc layer using$O_2$ -plasma. Synchrotron radiation photoelectron spectroscopy results showed that a new bond of Cu-O appeared and the energy difference between the highest occupied molecular orbital and$E_F$ is lowered by 0.20 eV after plasma treatment. Thus the hole injection barrier was lowered, reducing the turn-on voltage and increasing the quantum efficiency of OLEDs. -
We developed a panel of innovative solution-based approaches for synthesis of multicomponent sulfide phosphor materials. The application of these synthesis strategies allowed for preparation of high-purity and high-brightness
$BaAl_2S_4:Eu$ and$Ba_2SiS_4:Eu$ phosphors and led to the discovery of new phosphors suitable for application in the LED-based lighting including$Sr_2ZnS_3:Eu$ ,$CaBaSiS_4:Eu$ and$(Ba,Sr)_2ZnS_3:Eu$ . -
In this study, we report the room temperature synthesis and luminescence properties of white-light-emitting Rb(V,P)
$O_3$ . The vanadate phosphor, RbV$O_3$ , was synthesized by simple mixing of$RbCO_3$ and$V_2O_5$ at room temperature in air. New direct room temperature solidstate reaction is a cost-effective method to synthesize the above luminescent materials. -
Kim, Young-Kwan;Yoo, Young-Gil;Lee, Soon-Rewl;Kim, Min-Kyu;Kim, Jeong-Hee;Chung, Kyeong-Woon;Choi, Ick-Kyu;Song, Jay-Hyok;Song, Yu-Mi;Kim, Yoon-Chang;Heo, Eun-Gi;Zang, Dong-Sik;Chung, Chong-In 127
High luminance 3D built-in PDP panel was developed with newly adopted fast-decaying phosphor. Luminance of 3D PDP was increased about 40% by reducing the particle size of RGB phosphors and using$Y_3(Al,Ga)_5O_{12}:Ce^{3+}$ phosphor. Decay time of developed 3D PDP was 5.2ms/4.9ms for Red/Green color. -
Hirai, Nobukazu;Katsuhara, Mao;Yagi, Iwao;Yasuda, Ryoichi;Ushikura, Shin-Ich;Noda, Makoto;Moriwaki, Toshiki;Imaoka, Ayaka;Yoneya, Nobuhide;Yumoto, Akira;Nomoto, Kazumasa;Urabe, Tetsuo 131
We have developed a flexible OTFT backplane in which all the dielectrics are formed by solutionprocess in order to achieve low-cost and highthroughput manufacturing. The backplane successfully drives a flexible AM-OLED display with peak brightness of > 200 nit and the contrast ratio of > 1000:1 with great mechanical flexibility. -
After setting the gold standard for both industrial dropon-demand inkjet printheads and R&D printers for functional materials printing, FUJIFILM Dimatix has developed a printhead with the highest jetting frequency ever obtained. Operating at 100 kHz, the MEMS fabricated SAMBA printhead expands the capabilities of fabrication methods for display applications.
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Kwon, Oh-Seung;Marcia-Almanza-Workman, Marcia-Almanza-Workman;Braymen, Steve;Cobene, Robert;Elder, Richard;Garcia, Robert;Gomez-Pancorbo, Fernando;Hauschildt, Jason;Jackson, Warren;Jam, Mehrban;Jeans, Albert;Jeffrey, Frank;Junge, Kelly;Kim, Han-Jun;Larson, Don;Luo, Hao;Maltabes, John;Mei, Ping;Perlov, Craig;Smith, Mark;Stieler, Dan;Taussig, Carl 138
Progress in the development of a fully roll-to-roll selfaligned imprint process for producing active matrix backplanes with submicron aligned features on flexible substrates is reported. High performance transistors, crossovers and addressable active matrix arrays have been designed and fabricated using imprint lithography. Such a process has the potential of significantly reducing the costs of large area displays. The progress, current status and remaining issues of this new fabrication technology are reported. -
We demonstrated narrow and good aspect-ratio inkjet-printed silver lines with multi-time over-printing methods. By using this strategy, narrow silver lines were obtained with 200 nm thickness and their width and gap between printed lines of uniform narrow silver lines were 30
${\mu}m$ and 17${\mu}m$ , respectively. It also had good conductivity, sheet resistacne of 0.36${\Omega}/{\square}$ and specific resistance of$8{\mu}{\Omega}{\cdot}cm$ . In current stress test, narrow silver line with 30${\mu}m$ width was able to a current flow up to 50 mA (2.1A/$cm^2$ ). Using surface treatment on poly-arylate substrate with$UVO_3$ , we obtained clean-edge narrow line without any edge waviness. -
The cost effective structures and materials for the carbon nanotube (CNT) back light unit (BLU) are proposed. Simplified device structures and related electron emitter materials are prepared. CNT emitters were screen printed or remotely mounted on the back plate, and this enabled less than two photo patterning steps. Besides the cost benefits, operating voltage was dramatically decreased and higher current density was obtained
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We have developed 15 inch, 130 blocks local dimming FEL using printed CNT emitters, in which multiple FE blocks were built with a common gate electrode. Cathode electrode formed by the double-metal technique, in which an insulator is interposed between the addressing bus and cathode electrode.
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In this presentation, CD BLU optical film market and technology trends are introduced at first. Then hghly precise, cost-advantaged MNTECH's specialized Soft Mold replication Technology and its optic films are contained.
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Ha, Sang-Hoon;Jung, Dea-Hwa;Park, Ki-Jung;Kwon, Na-Hyun;Choi, Young-Jun;Chang, Ji-Ho;Cho, Young-Rae 152
A novel two-step surface treatment was developed and demonstrated for the carbon nanotube (CNT) cathode with highly efficient backlight unit application. An adhesive taping method was applied firstly and then followed by a post-heat treatment for the CNT cathode. During the postheat treatment process, some residues covering the CNTs were burned out. The post-heat treatment enhanced the emission current of the CNT cathode around 20% compared with that of no heat-treated sample. -
Lee, Seung-Eun;Song, Dong-Mee;Lee, Eun-Kyu;Bernatz, Georg;Goetz, Achim;Tarumi, Kazuaki;Taugerbeck, Andreas 156
New liquid crystal (LC) host mixtures and reactive mesogens (RMs) designed for the Polymer Sustainable Vertically Aligned (PS-VA) mode have been developed. The novel combination of LC host mixture with RMs enables to show superior LC display performance with high reliability and to contribute for the robust LC panel production process. -
Hasebe, Hiroshi;Kuwana, Yasuhiro;Nakata, Hidetoshi;Nishiyama, Isa;Takeuchi, Kiyofumi;Takatsu, Haruyoshi 159
A liquid crystalline monomer is applicable to fabricate a retarder in which various types of alignment are fixed. We have developed the monomer, UV-curable liquid crystal optimized for coating processes. Applications and materials for the retarder are reviewed. -
It is commonly found that liquid crystals stored in a common environment degrade with time, trapping more and more ion impurity in the materials. In this paper, we demonstrate how the electrical property of an old batch of liquid crystal can be effectively restored by a novel regenerative agent.
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We proposed a transflective liquid crystal display (LCD) with high aperture ratio using an electrophoretic particle layer (EPL). The transflective LCD consisted of the stacked LC layer and EPL which was acted as a switchable mirror under in-plane electrode structure. Without separation of reflective part and transmissive part in one pixel, a modeselectable display device can be obtained.
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Takaba, Hiromitsu;Serizawa, Kazumi;Suzuki, Ai;Tsuboi, Hideyuki;Hatakeyama, Nozomu;Endou, Akira;Kubo, Momoji;Kajiyama, Hiroshi;Miyamoto, Akira 169
We developed ultra-accelerated quantum chemical molecular dynamics and characterization simulators for study and design of plasma display panel (PDP) related materials. By use of these simulators, realistic structure of PDP materials is drawn on the computer. Furthermore, based on the structures, various properties such as secondary electron emission coefficient are successfully evaluated. In this report, we will discuss the theoretical secondary electron emission coefficient for several protecting layer materials and the effect of surface structure on the properties based on the result of atomistic simulations. -
We suggest a new protective layer for PDP consists of SrO and MgO double layer. This double layer structure protects SrO layer from the contamination by
$H_2O$ or$CO_2$ in the air and enable SrO to play as the main cathode material. It was confirmed that the high secondary electron emission characteristics of SrO by Xe ion can bring considerable driving voltage reduction and improvement of luminance and luminous efficacy in PDP. -
Here is presented the measurement on SrO- and SrCaO-PDP operated at lower voltage. SrO- and SrCaO-PDP attain high luminous efficacy at low voltage, where the breakdown voltage is 30 % lower than that of the ordinary MgO-PDP. A one-dimensional fluid model is applied for the simulation of PDP discharge. High VUV radiation efficiency is confirmed at high
${\gamma}_i$ and both low and high$V_s$ as in the experiment. Discharge analysis in simulation also shows that the high${\gamma}_i$ protective layer leads to high plasma density especially near the cathode electrode, being responsible for high efficiency. -
Comparative study of the dependence of the firing voltage of MgSrO and MgCaO protective layers on chemical composition was carried out. It was observed that the firing voltage increases when CaO/MgO or SrO/MgO ratio increases.
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In this paper, we study effect of charge balance on performance of blue phosphorescent organic light emitting diodes (OLEDs). Charge balance determines the location of recombination zone in the OLEDs. By tuning the charge balance in iridium (III) bis[(4,6-difluorophenyl)-pyridinate-N,C2']picolinate (FIrpic) based blue phosphorescent organic light-emitting devices (PHOLEDs) with a high mobility and high triplet energy electron transporting material, we were able to achieve a high current efficiency of 60 cd/A which is a 3X improvement over previous devices with 3,5'-N,N'-dicarbazole-benzene (mCP) host.
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A high efficiency deep blue phosphorescent organic light-emitting diode (PHOLED) was developed using a new wide triplet bandgap host material (PPO1) with a phenylcarbazole and a phosphine oxide unit. The wide triplet bandgap host material was synthesized by a phosphornation reaction of 2-bromo-Nphenylcarbazole with chlorodiphenylphosphine. A deep blue emitting phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine)iridium (FCNIr), was doped into the PPO1 host and a high quantum efficiency of 17.1 % and a current efficiency of 19.5 cd/A with a color coordinate of (0.14,0.15) were achieved in the blue PHOLED. The quantum efficiency of the deep blue PHOLED was better than any other quantum efficiency value reported up to now.
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We developed highly efficient blue PHOLEDs with reduced roll-off by using a mixed host structure. The balanced charge carrier injection and the distributed recombination zone within emissive layer resulted in a highly stable efficiency roll-off with quantum efficiencies of 20.1 and 18.1 % at a luminance of 1000 and 10000 cd/
$m^2$ . -
We report the multiple quantum well (MQW) structure for highly efficient red phosphorescent OLEDs. Various triplet quantum well devices from a single well to five quantum wells are realized using a wide band-gap hole and electron transporting layers, narrow band-gap host and dopant material, and charge control layers (CCL). The maximum external quantum efficiency of 14.8 % with a two quantum well device structure is obtained, which is the highest value among the red phosphorescent OLEDs using same dopant.
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One-dimensional rare earth oxide luminescence nano materials have been prepared by a combination method of sol-gel process and electrospinning. Systematic studie s on optical properties indicate that electrospinning is a facile and novel route for development luminescen ce materials that are useful in fluorescent lamps an d field emission dispalys.
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Luminescent films were prepared by infiltration of tris(dibenzoylmethane) mono(1, 10-phenanthroline) europium incorporated ormosil into colloidal
$SiO_2$ photonic crystal templates. The PL intensity of the infiltrated film into the template was about 13 times higher than that of the plane film prepared without the template. -
According to the recent demand for materials for use in various displays and solid state lightings, new phosphors with improved performance have been pursued consistently. Multi objective genetic algorithm assisted combinatorial material search (MOGACMS) strategies have been applied to various multi-compositional inorganic systems to search for new phosphors and to optimize the properties of phosphors.
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In this paper we will outline the opportunities for flexible OLED devices, both for display and solid-state lighting applications. We will present our recent data, and discuss future challenges, for low power consumption phosphorescent OLED technology fabricated on flexible substrates to enable a new generation of energy efficient electronic devices.
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The authors propose a novel dual mode liquid crystal display (LCD) which has both dynamic and memory operating LCD modes. The mode uses a horizontal switching and bistable chiral splay nematic (BCSN) LCD. The proposed dual mode does not require pixeldivision and has a higher aperture ratio and resolution than the previously proposed dual mode. Experimental results of the memory and dynamic mode show a high contrast ratio of over 100:1.
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Substrate-Assembling Technique using Adhesive Patterned Spacers for Flexible Liquid Crystal DisplaysWe proposed an enhanced substrate-assembling technique using adhesive patterned spacers for flexible liquid crystal displays (LCDs). The negative photoresister was used for the rigid columnar spacers and the strong substrate-bonding agent. The proposed technique is expected to be a good candidate for manufacturing method of flexible LCDs.
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New type simple, thin and flexible display unit with an exchangeable image-sheet coupled with a thin film light waveguide illuminated by color LEDs is proposed It displays the still picture like an e-paper, and the imagesheet with grooves formed by the PC and the cutting plotter can be easily replaced by another one.
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We have demonstrated several effective intermediate connectors in tandem organic light-emitting devices (OLEDs) using doped or nondoped organic p-n heterojunction. The influence of n-type or p-type organic layer in intermediate connectors on device performance has been investigated based on the understanding of interfacial electronic structures.
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Hwang, Sung-Kyung;Lim, Mee-Hyun;Han, Hae-Wook;Cho, Min-Su;Lee, Jae-Ho;Jang, Kyeng-Kun;Kang, Sin-Ho;Chung, In-Jae 229
This paper proposes a new design of ultra-slim color mixing lens (CML) for backlight unit (BLU), and presents simulated performance of the design. The novel color mixing structure has a shorter mixing length (< 1cm) than the existing color mixing structure, and achieves high efficiency and uniformity. -
In order to realize the high luminance and luminous efficacy MFFLs for LCD backlights, we optimized the phosphor profile to enlarge the surface area. The MFFL with the new phosphor profile shows a very wide luminance range from 2,600 to 17,000 nit with the corresponding luminous efficacy from 66 to 32.5 lm/W. The results were obtained with the color coordinate of the phosphor to be around (0.25, 0.23). And the single cell is expanded into a multi-structured configuration to realize a 32 inch-sized lamp by a simple repetition of the single cells, and a new driving scheme is proposed for an adaptive local dimming and scanning drive using dual auxiliary electrodes and bipolar drive scheme. Especially the ultra high luminance and luminous efficacy results suggest the duty time of illumination of the backlight unit can be significantly reduced.
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BaMg
$Al_{10}O_{17}$ (BAM) co-doped with$Eu^{2+}$ and$Mn^{2+}$ was synthesized in a solid-state reaction and their luminescence properties were investigated as functions of the concentrations of the sensitizer and activator. BAM:$Eu^{2+}$ had a broad blue emission band at 450 nm and BAM:$Mn^{2+}$ exhibited green emission at 514 nm. The energy transfer from$Eu^{2+}$ to$Mn^{2+}$ was mainly of the resonance-type via an electric dipole-quadrupole interaction. Additionally, the addition of various fluxes such as$AlF_3$ and$BaF_2$ in the synthesis improves the moist and thermal stability. This is particularly important for the phosphor in white light emitting diodes (LEDs). -
$Sr_2Si_5N_8:Eu^{2+}$ , one of the most recently developed phosphors for use in white light emitting diodes, exhibits a two-peak emission. Namely, the emission band of$Sr_2Si_5N_8:Eu^{2+}$ is deconvoluted into two Gaussian peaks irrespective of the$Eu^{2+}$ concentration. We examined the two-peak emission of$Sr_2Si_5N_8:Eu^{2+}$ by analyzing the time-resolved photoluminescence spectra. We revealed that the two-peak emission was closely associated with the energy transfer taking place between$Eu^{2+}$ activators located at two different crystallographic sites in the$Sr_2Si_5N_8$ structure. The experimental results coincided well with the rate equation model involving the crystallographic information of the host. -
The single phase
$Ba_2SiS_4$ doped with$Eu^{2+}$ was successfully synthesized by direct sulfurization of an oxide precursor prepared by a spray drying method using a novel water soluble silicon compound, which remains soluble in a given aqueous solution. The intensity of the emission peak of thus obtained$Ba_2SiS_4:Eu^{2+}$ was 1.75 times larger than that of a sample prepared by a solid state reaction method, and it approached 106% compared to one of the best commercially available YAG:$Ce^{3+}$ phosphor. -
A compact, flexible family of UV laser material processing systems has been developed to drive advancements in both large area processing and annealing of semiconductor surfaces. UV photons can either be applied via demagnifying a mask pattern image or by scanning a homogenized excimer beam across the substrate area. 193nm, 248nm and 308nm wavelength applications are supported.
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Effective methods for monitoring the quality of polycrystalline silicon (poly-Si) films are discussed. Raman spectroscopy is typically used to determine crystallinity of poly-Si, but this method has limitations for data gathering on large substrates for mass production of poly-Si TFT backplanes. Spectroscopic ellipsometry is proposed as an alternative for fast and simple estimation of poly-Si quality on large substrates. By using both ellipsometry and Raman spectroscopy, it is possible to determine whether the quality and uniformity of the poly-Si films meet the criteria required for mass production of TFT backplanes for AMOLED panels.
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The crystallization and activated annealing effect of Si films using an excimer laser and a new CW blue laser are described comparing with furnace annealing (SPC) for the application of advanced TFTs and future applications. Currently, pulsed ELA is used extensively as a LTPS process on glass substrates as the efficiency is high in UV region for thin Si film of 40- 60 nm thickness. ELA enables extremely low resistivity for both n- and p-typed Si films. On the other hand, CW BLDA enables the smooth Si surface having arbitral grains from micro-grains to anisotropic huge grain structure only controlling its power density.
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Fortunato, G.;Cuscuna, M.;Maiolo, L.;Maita, F.;Mariucci, L.;Minotti, A.;Pecora, A.;Simeone, D.;Valletta, A.;Bearzotti, A.;Macagnano, A.;Pantalei, S.;Zampetti, E. 258
In this work we present a process to fabricate lowtemperature polysilicon (LTPS) TFTs on polyimide (PI) layers, spin-coated on Si-wafer used as rigid carrier. This process has been then used to fabricate elementary circuits as well as circuits for sensor applications. -
Ternary oxides with controlled band gap energy and reduced reactivity against moisture and carbon dioxide gas were designed and studied as a potential material for protective layer of ac-PDPs. The results showed a significant reduction in firing voltage and improved environmental stability.
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The discharge condition of Plasma display panel(PDP) changes as the display time increases. Imaginary part of permittivity of dielectric material which is related to dielectric loss has been often neglected because of relatively small value compare to that of the real part. The thermal characteristics of PDPs with two different dielectrics has been studied and compared.
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Kim, Chul-Hong;Chae, So-Ra;Hwang, Yun-Tae;Kim, Min-Jae;Heo, Eun-Gi;Lee, Byung-Hak;Park, Yung-Jun;Chung, Chong-In;Kim, Dong-Jun;Cho, Jae-Hwi;Kim, Hyun-Don;Okamoto, Kuninori;Kweon, Tae-Jong 269
We investigated on the sintering behaviors and electrical properties of photo-sensitive aluminum (Al) electrode materials in plasma display panels. General characteristics of Al electrodes was totally different to that of conventional Ag materials; resistivity was decreased with the increasing of metal particle sizes and the amount of frit content and there is almost no width difference between developed and fired electrodes layers. Microstructures of fired electrodes revealed that Al electrodes had different mechanism on necking between metal particles and making electrical conducting path. Chemical durability (especially, antialkalinity) and adhesion of Al electrodes must be carefully controlled. Nevertheless there are difficulties of processing Al electrodes, we developed and optimized photo-sensitive Al materials as address electrodes without any changes of existing patterning equipment and sintering conditions. -
A new green phosphor, (
$Mg_{1-x-yZnx)$ )$Al_2O_4:Mn^{2+}{_y}$ (0 x 0.6, 0.001 y 0.01), was synthesized by a flux-assisted solid reaction and its vacuum ultraviolet (VUV) excitation and emission characteristics were examined in this study. The chromaticity and peak intensity of the$(Mg_{0.79}Zn_{0.2})Al_2O_4:Mn^{2+}{_{0.01}}$ (x = 0.177, y = 0.745) phosphor were found to be more desirable than that of$Zn_2SiO_4:Mn^{2+}$ (x = 0.216, y = 0.72) phosphor as a green primary color. -
In this paper we demonstrate how to use optical simulation to enhance OLED performance. Using stateof-the-art p-i-n OLEDs, we validate our optical model by fitting key figures like current, power, and quantum efficiencies to the experimental results. We finally provide general design guidelines for optically optimized OLEDs.
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Improving the visual contrast in OLED displays is another important issue to address with a significant technological implication. The use of a gradient refractive index anode shows promise for contrast improvements in OLEDs. This talk will discuss the progress in developing gradient refractive index TCO anode for application in high contrast OLEDs.
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Lamansky, Sergey;Le, Ha;Hao, Encai;Stegall, David;Wang, Ding;Lu, Yi;Zhang, Jun-Ying;Smith, Terry L.;Gardiner, Mark;Kreilich, Leslie;Anim-Addo, Jonathan;McCormick, Fred B. 282
Nanostructured OLED light extraction films have been made via roll-to-roll coating processes. Their on-axis and integrated outcoupling efficiencies reach 2X and 1.3-1.8X, respectively. Optical performance and effects of the nanostructured film on pixel blur and image ghosting will be discussed. -
Elasticoluminescence(ESL) is a kind of mechanoluminescence(ML). ESL materials are novel functional materials that can convert elastic deformation energy into visible light directly. Utilizing the materials, novel sensing devices and various applications are now under development. These materials can allow direct viewing of stress distribution.
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Using a mechano-luminescent (ML) material enabling the visualization of fast propagating cracks with bridging or transformed wake evolutions under a conventional loading condition, the quasi-dynamic fracture mechanisms in association with two different types of crack wake developments wewe investigated in various ceramic.
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Onuma, Hiroaki;Suehiro, Takayuki;Suzuki, Ai;Tsuboi, Hideyuki;Hatakeyama, Nozomu;Endou, Akira;Takaba, Hiromitsu;Kubo, Momoji;Sato, Tsugio;Miyamoto, Akira 290
We both theoretically and experimentally investigated the luminescence wavelength control of the$Eu^{2+}$ -doped$CaAlSiN_3$ (CASN:$Eu^{2+}$ ). To modify emission wavelength, Na-doped and Mg-doped CASN:$Eu^{2+}$ (NCASN:$Eu^{2+}$ and MCASN:$Eu^{2+}$ ) have been studied. According to quantum chemistry calculation result, we synthesized NCASN:$Eu^{2+}$ and MCASN:$Eu^{2+}$ . NCASN:$Eu^{2+}$ and MCASN:$Eu^{2+}$ showed shorter emission wavelength than that of CASN:$Eu^{2+}$ . -
Onuma, Hiroaki;Yamashita, Itaru;Serizawa, Kazumi;Suzuki, Ai;Tsuboi, Hideyuki;Hatakeyama, Nozomu;Endou, Akira;Takaba, Hiromitsu;Kubo, Momoji;Miyamoto, Akira 294
We computationally investigated the effects of oxygen and alkaline-earth on the emission wavelength of the$Eu^{2+}$ -doped oxide phosphor. Using QSPR method, we found that the oxygen and alkaline-earth atom around the Eu atom increase and decrease the emission wavelength, respectively. We also investigated the$Eu^{2+}$ -doped sulfide, nitride, and oxynitride phosphors. -
Touch screen using in portable devices is expanding continuously, has become particularly strong in mobile phones. These trends are able to open the "New Horizon" which refers the design and usability of mobile phones and provide "New Experience" which users have never been experienced on mobile phones. This research argues new usability issues and important points which can be occurred in touch based mobile phones as user experience point of view.
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This study is a study on Silver Class' percipience on mobile phone's LCD and a research has been conducted for configuration of an effective menu. First of all, the minimum sizes for Silver Class to perceive LCDs of mobile phones and sizes of icons or fonts within the LCDs were measured, and icons easily perceived by Silver Class were analyzed for configuring menu. These measurements it to understand what kind of display configuration has the highest demand by comparing a general public group in their 25 to 35 and a Silver Class group above 65 and suggest an alternative for that.
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As the technology advances, the product design process is also being complicated. These days, it is common for engineers to consider socio-psychological factors as well as technological elements in the design process. In this work, I will explain why and how engineers make allowances for human factors in developing and designing technological products.
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We may need to consider 'display' interface and product design as distinct from traditional user- and technologydriven product design. Technology-dominated product development may lead users to demand another 'technological improvement' rather than 'design improvement.' This cycle of product development may cause both users and producers to disregard the potential of 'display' technology and interface. We must develop a better understanding of significant and unique 'display' potential in comparison with 'real' world communications and current sociological and technological contexts.
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Korean digital product users' tends to be participationoriented. They hope that their expectations are reflected in the outcome. Furthermore, they look toward customizationoriented. They want product differentiation for only their own goods. They come to take a prudent and particular attitude. Korean display industry is under extending the share of the international market these days. This report covers the direction of the display industry design through analyzing the trend of the Korean digital product users'.
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We have fabricated vertical-type organic transistors (static induction transistors; SITs) with built-in nano-triode arrays formed in parallel by a colloidal-lithography technique. Using this technique, we could fabricate a microstructure in a lateral direction within a large-scale organic device without relying on photolithography. The organic transistor showed low operating voltages, high current output, and large transconductance.
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New X-shaped crystalline molecules have been synthesized through various coupling reactions and their electronic properties were investigated. They exhibit good solubility in common organic solvents and good self-film forming properties. They are intrinsically crystalline as they exhibit well-defined X-ray diffraction patterns from uniform and preferred orientations of molecules. They also exhibited high field effect mobilities in thin film transistor (TFT) and good device performances.
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Yun, Ho-Jin;Baek, Kyu-Ha;Park, Kun-Sik;Shin, Hong-Sik;Ham, Yong-Hyun;Lee, Ga-Won;Lee, Ki-Jun;Wang, Jin-Suk;Do, Lee-Mi 312
We have fabricated pentacene based organic thin film transistors (OTFTs) with formulated poly[4-vinylphenol] (PVP) gate dielectrics. The gate dielectrics is composed of PVP, poly[melamine-coformaldehyde] (PMF) and photo-initiator [1-phenyl-2-hydroxy-2-methylpropane-1-one, Darocur1173]. By adding small amount (1 %) of photo-initiator, the cross-linking temperature is lowered to$115^{\circ}C$ , which is lower than general thermal curing reaction temperature of cross-linked PVP (>$180^{\circ}C$ ). The hysteresis and the leakage current of the OTFTs are also decreased by adding the PMF and the photoinitiator in PVP gate dielectrics. -
We report the preparation of novel nanofiber organic semiconductors that can be utilized as the active channel materials in the field effect transistors (FETs). The nanofibers produced by the electrospinning reveals the excellent performances (mobility ~ 0.16
$cm^2$ /V) due to thier highly ordered molecular packing in the polymer matrix. -
Cho, Doo-Hee;KoPark, Sang-Hee;Yang, Shin-Hyuk;Byun, Chun-Won;Cho, Kyoung-Ik;Ryu, Min-Ki;Chung, Sung-Mook;Cheong, Woo-Seok;Yoon, Sung-Min;Hwang, Chi-Sun 318
We have studied transparent top gate Al-Zn-Sn-O (AZTO) TFTs with an$Al_2O_3$ protective layer (PL) on an active layer. We also fabricated a transparent 2.5 inch QCIF+AMOLED display panel using the AZTO TFT back-plane. The AZTO active layers were deposited by RF magnetron sputtering at room temperature and the PL was deposited by ALD with two different processes. The mobility and subthreshold slope were superior in the cases of the vacuum annealing and the oxygen plasma PL compared to the$O_2$ annealing and the water vapor PL, however, the bias stability was excellent for the TFTs of the$O_2$ annealing and the water vapor PL. -
Amorphous oxide semiconductors (AOSs) are expected as new channel materials in TFTs for largearea and/or flexible FPDs, and several prototype displays have been demonstrated in these five years since the first report of AOS TFT. In this paper, we review fundamental materials science of AOSs that have been clarified to date in connection with operation characteristics of AOS TFTs.
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We investigated the degradation of
$In_2O_3-Ga_2O_3$ -ZnO (IGZO) thin-film transistors (TFTs), which is promising device for driving circuits of nextgeneration displays. We performed the electronic stress test by applying gate and drain voltage. We discussed the degradation mechanism by thermal analysis and device simulation. -
Ryu, Min-Ki;KoPark, Sang-Hee;Yang, Shin-Hyuk;Cheong, Woo-Seok;Byun, Chun-Won;Chung, Sung-Mook;Kwon, Oh-Sang;Park, Eun-Suk;Jeong, Jae-Kyeong;Cho, Kyoung-Ik;Cho, Doo-Hee;Lee, Jeong-Ik;Hwang, Chi-Sun 330
Highly stable bottom gate thin film transistors(TFTs) with a zinc indium tin oxide(Zn-In-Sn-O:ZITO) channel layer have been fabricated by rf-magnetron co-sputtering using a indium tin oxide(ITO:90/10), a tin oxide and a zinc oxide targets. The ZITO TFT (W/L=$40{\mu}m/20{\mu}m$ ) has a mobility of 24.6$cm^2$ /V.s, a subthreshold swing of 0.12V/dec., a turn-on voltage of -0.4V and an on/off ratio of >$10^9$ . When gate field of$1.8{\times}10^5$ V/cm was applied with source-drain current of$3{\mu}A$ at$60^{\circ}C$ , the threshold voltage shift was ~0.18 V after 135 hours. We fabricated AM-OLED driven by highly stable bottom gate Zn-In-Sn-O TFT array. -
A series of microcavity plasma devices having various electrode geometries were investigated for the display and lighting applications. Addressable, self-assembled Al/
$Al_2O_3$ electrodes were fabricated in a thin, flexible single sheet of Al foil. And, enhanced luminance and efficient microplasmas are achieved by precise control of the cross-sectional geometry and surface morphology of the cavities within the microplasma devices. New microdischarge system fabricated in various substrates will be introduced. -
A flexible photoluminescent display device was proposed and fabrication technology with a low process temperature was investigated in order to improve its reliability. The proposed flexible photoluminescent display showed good characteristics in reliability and flexibility. The lifetime of the proposed flexible photoluminescent displays with organics components is estimated to be approximately more than 10,000 hours.
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A transparent plasma display was developed using transparent glass barrier ribs. Glass barrier ribs were fabricated via a wet etching process. Glass barrier ribs created using a top and bottom etching process showed better transparency compared to those created through only a top etching process. A see-through phosphor layer was obtained by coating the sidewall of the barrier ribs with a conventional opaque phosphor. A fabricated prototype of a transparent plasma display was clear enough to see the background beyond the panel and was well operated by a conventional driving scheme. The maximum luminance was 1150 cd/
$m^2$ and the maximum luminous efficacy was 1.35 lm/W in a Ne+13.5%Xe gas-mixture and green cells. -
Bright light-emitting single crystal organic field-effect transistors (FETs) based on highly luminescent oligo(p-phenylenevinylene) (OPV) derivatives are demonstrated. Although OPV single crystal FETs show both p - and n - type FET operation, we found that an increase in the conjugation length of the OPV derivatives from three phenylene rings to five phenylene rings results in an improvement in the electron mobility by an order of magnitude, while retaining the high hole mobility with intense electroluminescence.
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We investigated the doping effects of
$ReO_3$ in different p-type organic semiconductors on the formation of charge transfer complexes and the electrical conductivity by comparing the absorption in ultraviolet-visible-nearinfrared (UV-Vis-NIR) and the current density-voltage characteristics of the hole only devices, respectively. The large energy difference between the HOMO level of host and Fermi energy level of dopant (${\Delta}E$ =$E_{HOHO,host}$ -$E_{F,dopant}$ ) gives higher concentration of CT complexes and enhanced conductivity. -
While the comparatively high MW would make the employed molecules extremely difficult to vacuum-evaporate, and result in poor device performance, the wet-process has been proven to be quite effective and convenient as usual to the fabrication of high-efficiency OLEDs composing high MW components.
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In the fabrication of inverted top-emitting organic light emitting diodes (ITOLEDs), the sputtering process is needed for deposition of transparent conducting oxide (TCO) as top anode. Energetic particle bombardment, however, changes the physical properties of underlying layers. In this study, we examined plasma process effects on tungsten oxide (
$WO_3$ ) hole injection layer (HIL). From our results, we suggest the theoretical mechanism to explain the correlation between the physical property changes caused by plasma process on$WO_3$ HIL and degradation of device performances. -
In recent years, flexible e-paper displays based on electrophorectic materials continue to attract enormous interest from technologists and are expected to be in the market soon. To realize a flexible e-paper, several key technologies for TFT backplane have been developed, while it still lacks good color reproduction and requires input function for use in its various applications. Thus, the technical issues for implementing color and touch functions in a flexible e-paper are discussed, and then our development status along with technology trend of it is described.
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Lee, Y.E.;Cho, Y.T.;Choi, Y.G.;Park, S.C.;Lee, M.H.;Park, Y.M.;Kim, D.Y.;Kim, C.H.;An, C.H.;Kim, H.S. 360
In this paper, we describe new approach of ink particle fabrication method for electrophoretic display(EPD) with low voltage and rapid response time. Nano-size ink particles which fabricated using non-aqueous base modified emulsion process and micron-scale particles by non-solvent particle fabrication process are discussed. Finally, specially designed particles and panel structure fabricated considering the interactions between particle/particle, particle/media or particle/electrode dramatically reduce the driving voltages to${\pm}$ 10V and improve the response time of less than 100msec and white reflectance of 58% for EPD using dielectric fluid as a medium. In case of EPD adapting micron-sized electrophoretic particles and a medium of air, the saturation voltage could be reduced to${\pm}$ 40V and having white reflectance of 45% without scarification of electrophoretic mobility of the particles. -
We successfully fabricated flexible electronic paper display (EPD) by using toner particles on plastic (PC) substrate. It has high resolution (WVGA : 800
${\times}$ 480) and 7 inch diagonal viewable image size. The response time was about 0.25 msec at 90 V, a contrast ratio of about 2, a driving voltage of 60 V which we successfully demonstrated to display several images at. -
Cha, Hye-Yeon;Lee, Choong-Hee;Lee, Sang-Moon;Kwak, Jeong-Bok;Chae, Kyoung-Soo;Lee, Hee-Bum;Lee, Young-Woo;Lee, Chong-Seo;Oh, Yong-Soo;Lee, Hwan-Soo 367
Optically anisotropic rotating balls were disposed in a monolayer, and controllably closely packed with respect to one another in the monolayer. The close packed monolayer configuration provided high brightness and improved contrast. The monolayer rotating ball display (MRB) electrically demonstrated a fast response time of approximately 40 msec at a voltage of 30 V. Measurements of the rotation as a function of voltage led to surface charge density for the balls in the range of 3-4${\mu}C/m^2$ . -
X-ray lithography was employed to fabricate ITO-less high resolution sustain electrodes for plasma display panel (PDP). A polyimide film based X-ray mask and Xray sensitive Ag electrode paste were fabricated to check their effect on the patterning of Ag electrodes with less than 30
${\mu}m$ in width. The X-ray lithographic method was found to be useful for the high resolution sustain electrode patterns due to the high penetration power and low scattering property of X-ray source. -
Tsai, Jung-Ruey;Li, Chi-Shiau;Tsai, Shang-Yu;Chen, Jyun-Ning;Chien, Po-Hsiu;Feng, Wen-Sheng;Liu, Kou-Chen 374
The characteristics of the deposited thin films of the zinc oxide (ZnO) at different oxygen pressures will be elucidated in this work. The resistivity of ZnO thin films were dominated by the carrier concentration under high oxygen pressure conditions while controlled by the carrier mobility at low oxygen ambiences. In addition, we will show the characteristics of the transparent ZnO based thin film transistor (TFT) fabricated at a full room temperature process with gate dielectric of gadolinium oxide ($Gd_2O_3$ ) thin films. -
Hong, Won-Eui;Lee, Seog-Young;Chung, Jang-Kyun;Lee, Joo-Yeol;Ro, Jae-Sang;Kim, Dong-Hyun;Park, Seung-Ho;Kim, Cheol-Su;Lee, Won-Pil;Kim, Hye-Dong 378
As a Joule-heat source, a conductive Mo layer was used to crystallize amorphous silicon for AMOLED backplanes. This Joule-heating induced crystallization (JIC) process could produce poly-Si having a grain size ranging from tens of nanometers to greater than several micrometers. Here, the blanket (single-shot whole-plane) crystallization could be achieved on the$2^{nd}$ and the$4^{th}$ generation glass substrate. -
Cheong, Woo-Seok;Lee, Jeong-Min;Jeong, Jae-Kyeong;KoPark, Sang-Hee;Yoon, Sung-Min;Cho, Doo-Hee;Ryu, Min-Ki;Byun, Chun-Won;Yang, Shin-Hyuk;Chung, Sung-Mook;Cho, Kyoung-Ik;Hwang, Chi-Sun 382
In this study, high stable oxide thin-film transistors (TFTs) have been developed by using several approaching techniques, which including a change of the channel composition ratio in multi-component oxide semiconductors, a change of TFT structure with interfacial dielectric layers, a control of interface roughness, a channel-doping method, and so on. -
KoPark, Sang-Hee;Cho, Doo-Hee;Hwang, Chi-Sun;Ryu, Min-Ki;Yang, Shin-Hyuk;Byun, Chun-Won;Yoon, Sung-Min;Cheong, Woo-Seok;Cho, Kyoung-Ik 385
We have investigated the effect of the device structure on the performance of polycrystalline ZnO TFT and amorphous AZTO TFT with top gate and bottom gate structure. While the mobility of both TFTs showed relatively similar value in a top and bottom gate structure, bias stability was quite different depending on the device structure. Top gate TFT showed much less Vth shift under positive bias stress compared to that of bottom gate TFT. We attributed this different behavior to the defects formation on the gate insulator induced by energetic bombardment during the active layer deposition in a bottom gate TFT. We suggest the top gate oxide TFT would show more stable behavior under the Vgs bias. -
Mann, Mark;Li, Flora;Kiani, Ahmed;Paul, Debjani;Flewitt, Andrew;Milne, William;Dutson, James;Wakeham, Steve J.;Thwaites, Mike 389
Metal oxides have been proposed as an alternative channel material to hydrogenated amorphous silicon in thin film transistors (TFTs) because their higher mobility and stability make them suitable for transistor active layers. Thin films of indium zinc oxide (IZO) were deposited using a High Target Utilization Sputtering (HiTUS) system on various dielectrics, some of which were also deposited with the HiTUS. Investigations into bottom-gated IZO TFTs have found mobilities of 8$cm^2V\;^1s^{-1}$ and switching ratios of$10^6$ . There is a variation in the threshold voltage dependent on both oxygen concentration, and dielectric choice. Silica, alumina and silicon nitride produced stable TFTs, whilst hafnia was found to break down as a result of the IZO. -
Yang, Shin-Hyuk;Cho, Doo-Hee;KoPark, Sang-Hee;Lee, Jeong-Ik;Cheong, Woo-Seok;Yoon, Sung-Min;Ryu, Min-Ki;Byun, Chun-Won;Kwon, Oh-Sang;Cho, Kyoung-Ik;Chu, Hye-Yong;Hwang, Chi-Sun;Ahn, Taek;Choi, Yoo-Jeong;Yi, Mi-Hye;Jang, Jin 393
We fabricated oxide and oxide/organic hybrid TFTs on a glass substrate using the photolithography process under$200^{\circ}C$ . We adopt the solution processed organic ferroelectric materials of P(VDF-TrFE) and polyimide (KSPI) insulator for 1-T structure memory and flexible device, respectively. All devices have successfully operated and showed the possibility of hybrid TFTs for the application to the flexible electronic devices. -
Thin-film transistors (TFTs) with an aluminum indium oxide (AIO) channel layer were fabricated via a simple and low-cost sol-gel process. Effects of annealing temperature and time were investigated for better TFT performance. The sol-gel AIO TFTs were annealed as low as
$350^{\circ}C$ . They exhibit n-type semiconductor behavior, a mobility higher than 19$cm^2/V{\cdot}s$ and an onto-off current ratio greater than$10^8$ . -
In this paper we report a micro projector including of RGB sources, a
$3{\times}1$ Fiber Optic Color Synthesizer (FOCS), and a two dimensional micro mechanical scanning mirror. We further report a modifier micro collimator which can enhance the resolution of the screened image. -
A variety of power reduction technologies is introduced and the benefits of the technologies are discussed. PenTile
$^{(R)}$ DBLC (Dynamic Brightness LED Control) combined with SABC (Sensor-Based Adaptive Brightness Control) enables to achieve the average LED power consumption to one third. The panel power reduction of 25% can be achieved with low power driving technology, ALS (Active Level Shifter). MIP (Memory In Pixel) is expected to be useful in transflective display because the whole display area can be utilized in reflective mode with power consumption of 1mW. -
HYPOLED is a collaborative European project that commenced in 2008. It is targeted toward "High-Performance OLED-Microdisplays for Mobile Multimedia HMD and Projection Applications". In this paper, we describe the initial objectives and present draft specifications for devices, the personal display system and micro-projection unit. Initial results are shown and discussed.
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Vogel, Uwe;Herold, Rigo;Kreye, Daniel;Richter, Bernd;Bunk, Gerd;Reckziegel, Sven;Scholles, Michael;Grillberger, Christiane;Toerker, Michael;Amelung, Jorg 408
First demonstrators of bi-directional OLED microdisplay devices have been developed and integrated into see-through HMD optics. The device combines 'display' and 'imaging' by nested OLED pixels and photodetectors in a single CMOS chip. Major aim of this integration is to provide capabilities for eyetracking to achieve gaze-based human-displayinteraction. -
Han, Chang-Wook;Pieh, Sung-Hoon;Sung, Chang-Jae;Kim, Hwa-Kyung;Pang, Hee-Suk;Choi, Hong-Seok;Lee, Nam-Yang;Ahn, Byung-Chul 411
We report single and two-stacked WOLED. Two-stacked WOLED structure adopts fluorescent blue EML and phosphorescent (red+green) EML. Current efficiency, EQE and color coordinate of two-stacked WOLED are 54.5cd/A, 28.8% and CIExy (0.322, 0.345), respectively. Those of single WOLED are also 20cd/A, 10% and CIExy (0.29, 0.37), respectively. Dual-plate OLED Display (DOD) employing the single WOLED shows high aperture ratio up to 67% in 2-inch panel of which pixel size is equivalent to that of 32 inch Full HD. -
Color stable and efficient two wavelength white organic light emitting diodes (OLEDs) were fabricated using a iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,
$C^2$ '] picolinate (FIrpic) as a blue phosphorescent emitter and a bis(1-phenylisoquinolinato-$C^2$ ,N)iridium (acetylacetonate) ((piq)$_2$ Ir(acac)) as a red phosphorescent emitter. The emitting layers consist of two blue emitting layers and one red emitting layer which is between the two blue layers. The device reaches the peak efficiencies of 7.84 % and 10.3 cd/A at 0.6 mA/$cm^2$ . Furthermore, there was little change of EL spectra according to current density change in the device. -
Seo, Ji-Hoon;Park, Jung-Sun;Kim, Jun-Ho;Koo, Ja-Ryong;Seo, Bo-Min;Lee, Kum-Hee;Park, Jeong-Keun;Je, Jong-Tae;Yoon, Seung-Soo;Kim, Young-Kwan 418
The Authors have demonstrated high efficiency hybrid white organic light-emitting diodes (HWOLED) for reduced efficiency roll-off and color stability. It was shown that HWOLED fabricated in this study have the maximum luminance of 46 420 cd/$m^2$ at 8 V (turn-on voltage of 2.7 V), external quantum efficiency of 13.18%, power efficiency of 28.75 lm/W at 1 000 cd/$m^2$ , and reduced efficiency roll-off of 2.7 times than control white device. The HWOLED also showed the stable color shift with$\Delta$ Commission Internationale de I'Eclairage coordinates coordinates of${\pm}$ (0.00, 0.00) from 100 to 10000 cd/$m^2$ . -
Hu, Tarng-Shiang;Wang, Yi-Kai;Peng, Yu-Rung;Yang, Tsung-Hua;Chiang, Ko-Yu;Lo, Po-Yuan;Chang, Chih-Hao;Hsu, Hsin-Yun;Chou, Chun-Cheng;Hsieh, Yen-Min;Liu, Chueh-Wen;Hu, Jupiter 421
We successfully fabricated 4.7-inch organic thin film transistors array with$640{\times}480$ pixels on flexible substrate. All the processes were done by photolithography, spin coating and ink-jet printing. The OTFT-Electrophoretic (EP) pixel structure, based on a top gate OTFT, was fabricated. The mobility, ON/OFF ratio, subthreshold swing and threshold voltage of OTFT on flexible substrate are: 0.01 ^2/V-s, 1.3 V/dec, 10E5 and -3.5 V. After laminated the EP media on OTFT array, a panel of 4.7-inch$640{\times}480$ OTFT-EPD was fabricated. All of process temperature in OTFT-EPD is lower than$150^{\circ}C$ . The pixel size in our panel is$150{\mu}m{\times}150{\mu}m$ , and the aperture ratio is 50 %. The OTFT channel length and width is 20 um and 200um, respectively. We also used OTFT to drive EP media successfully. The operation voltages that are used on the gate bias are -30 V during the row data selection and the gate bias are 0 V during the row data hold time. The data voltages that are used on the source bias are -20 V, 0 V, and 20 V during display media operation. -
We fabricated flexible OTFT-backplanes with combining printing technique and conventional photolithography process for the electrophoretic display(EPD). The active area size of backplane was 6" in diagonal direction and consisted of
$192{\times}150$ pixels, containing 1 OTFT employed bottom contact structure and 1 capacitance in each pixel. -
Jin, Yong-Wan;Kim, Joo-Young;Koo, Bon-Won;Song, Byong-Gwon;Kim, Jung-Woo;Kim, Do-Hwan;Yoo, Byung-Wook;Lee, Ji-Youl;Chun, Young-Tea;Lee, Bang-Lin;Jung, Myung-Sup;Park, Jeong-Il;Lee, Sang-Yoon 431
We developed 4.8 inch WQVGA e-paper on plastic substrate using organic field effect transistors (OFETs). Polyethylene naphthalate (PEN) film was used as a flexible substrate and arrays of OFETs with bottom-gate, bottom-contact structure were fabricated on it. Lowtemperature curable organic gate insulating materials were employed and polymer semiconductor solutions were ink-jetted on arrays with high-resolution. At all steps, process temperature was limited below$130^{\circ}C$ . Finally, we could drive flexible e-paper displays based on OFET arrays with the resolution of 100 dpi. -
To realize the advantages of e-Paper, driving systems should be separated from panels to keep its superiority in thin, light, and flexible. For this purpose, this paper develops a panel hot-plugging driving system for R2R cholesteric LCD. Its performance is verified by implementing an e-Badge application. Satisfactory results are obtained.
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In this paper, we describe the latest LCD driving technology which helps to realize the stereoscopic 3D display system with FHD resolution by using the 240Hz LCD panel. The 240Hz LCD system has two times more data than current 120Hz and can cover the crosstalk due to the progressive scan.
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A wavelength multiplexing based stereoscopic 3D-LCD will be introduced. A new 120 Hz scanning RGB-backlight unit was developed. This backlight module was combined with a standard 120Hz LCD. The 3D-LCD based on interference filter glasses offers an outstanding channel separation and a wide viewing angl.
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In this paper, an accurate ray-tracing based visual analysis method of lenticular 3D liquid liquid crystal display (LCDs) and some analysis results are presented. In the developed method, the geometric optics analysis is performed on the single 3D unit pixel of 3D lenticular LCD. It is shown that the display characteristics of 3D lenticular LCD panels of arbitrary size can be evaluated through the 3D unit pixel analysis. The analysis results of a few representative structures of 3D lenticular LCDs are compared.
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In this paper, we propose a system which is a 2D/3D switchable module. The display mode can be s witched by user or content.
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Okada, Hiroyuki;Matsui, Kenta;Naka, Shigeki;Shibata, Miki;Ohmori, Masahiko;Kurachi, Naomi;Sawamura, Momoe;Suzuki, Shin-Ichi;Inoue, Toyokazu;Miyabayashi, Takeshi;Murase, Makoto;Takao, Yuuzou;Hibino, Shingo;Bessho, Hisami 449
Ink-jet printed (IJP) self-aligned (SA) organic light emitting diodes (OLEDs) and its application to light emitting seal have investigated. Ink-jet printing of light emitting material is carried out onto transparent anode covered with insulating material. Laminated light emitting seal with SA IJP OLED without photo - lithographic process and any vacuum process, noncontact type electromagnetic power supply without electric power supply line, and light emitting tag with network type RF communication terminal by controlling display information were demonstrated. -
We present a new generation of imaging colorimeter that ensures improved accuracy and sensitivity for shorter measurement times. The imaging optics is telecentric on the sensor and allows measurements at any distances without additional calibration. A new technology is used to make the color filters and flat densities. Imaging polarimetry at fixed wavelength is also possible with the same instrument.
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The thermo-optical characteristics of new generation fully reversible diacetylene vesicles, DCDDA-mono-mBzA and DCDDA-bis-mCPE, and their solid film composites are utilized as thermochromic display materials. Conspicuous color intensity of their solid films and blue-to-red color shift with non-fluorescent to fluorescent switching at
$100^{\circ}C$ make them promising materials for dual color thermally actuated display devices of the near future. -
Oh, Min-Suk;Kim, Yong-Hoon;Park, Sung-Kyu;Han, Jeong-In;Lee, Ki-Moon;Im, Seong-Il;Lee, Byoung-H.;Sung, Myung-M. 461
We report on the fabrication of ZnO-based thin-film transistor (TFT) inverters with top and bottom gate structures with$Al_2O_3$ dielectrics grown by atomic layer deposition (ALD). Since the top gate ZnO-based TFT showed somewhat lower field effect mobility than that of the bottom gate device, our ZnO-based TFT inverters were designed with identical dimensions for both channels. This TFT inverter device demonstrated an high voltage gain at a low supply voltage of 5 V and clear dynamic behavior. -
Hwang, Tong-Hun;Yang, Ik-Seok;Kim, Kang-Nam;Cho, Doo-Hee;KoPark, Sang-Hee;Hwang, Chi-Sun;Byun, Chun-Won;Kwon, Oh-Kyong 464
A new level shifter using n-channel aluminum-doped zinc tin oxide (AZTO) thin film transistors (TFTs) was proposed to integrate driving circuits on qVGA panels for mobile display applications. The circuit used positive feedback loop to overcome limitations of circuits designed with oxide TFTs which is depletion mode n-channel TFTs. The measured results shows that the proposed circuit shifts 10 V input voltage to 20 V output voltage and its power consumption is 0.46 mW when the supply voltage is 20 V and the operating frequency is 10 kHz. -
Choi, Sang-Moo;Goo, Bon-Seok;Kang, Jin-Goo;Kim, Keum-Nam;Kim, Yang-Wan;Choi, Woong-Sik;Kim, Byung-Hee 466
The life time of AMOLED displays has been dependent on OLED materials up to this point. In particular, image sticking (burn-in) has been one of the most critical issues for AMOLEDs. This paper proposes image sticking compensation AMOLED pixel circuits to address the problem without requiring process or material improvements to the OLED itself. We verified the performance of those circuits by simulation and actual panel implementation. -
Moon, Su-Hwan;Lim, Hong-Youl;Kim, Dae-Kyu;Lee, Min-Kyung;Ko, Kyung-Tai;Lee, Jun-Ho;Yoon, Sung-Hoe;Kim, Byeong-Koo 470
We have developed a novel driving method, Six times Rate Driving(SRD) for the purpose of making cost competitive TFT-LCD. By applying SRD method to an a-Si TFT-LCD, the driving rate was increased six times as it was named but the number of data lines and so its D-Ics were reduced to one sixth of the conventional one which resulted in the cost saving of that much. We also newly designed the gate driver in order to avoid any expansion of the bezel width caused by applying SRD. Our newly developed driving technology, SRD was successfully applied to 7.0-inch WSVGA (1024${\times}$ 600) TFT-LCD which can be driven with only one data D-IC and here introduced. -
As a substitute of ITO material, carbon nanotube (CNT) is widely studied for transparent conductive film (TCF). Current sheet resistance of CNT-TCF is about 100
${\Omega}$ /sq at 80% transmittance. But CNT-TCF performance in manufacturable level is about 500${\Omega}$ /sq at 83% based on the Topnanosys Co's result. Therefore, critical issue in CNT-TCF research is to reduce the sheet resistance with manufacturing reliability. In this report, recent developments using CNT-TCF are introduced. Touch panel, transparent LED signboard, transparent speaker and transparent heater are representative examples. Also I describe the future issues and prospect of CNT-TCF for the flexible display. -
The smallest green laser containing a built-in temperature controlling unit has been demonstrated. The device volume was just 0.5 cubic centimeters, which is nearly the same size as existing red and blue diode lasers, has an electrical-to-optical conversion efficiency of 10% and 150 mW power output. Furthermore as an alternative approach for compact green laser development, a quasi-phase matching method with wide spectral bandwidth for the reduction of speckle noise will be presented.
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This experiment implemented a laser projection system that used the 2D MEMS scanner as the driving method for the display device. The 2D MEMS scanner, which can scan the images horizontally and vertically, was applied to drive the projection system using the interlaced scanning method. The laser was directly modulated to implement the grayscale and the images were WVGA resolution quality.
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For a new generation of white light sources, we present the first example of a concentration-independent ultimate white-light-emitting molecule based on excited-state intramolecular proton transfer materials. Our molecule is composed of covalently linked blue- and orange-light-emitting moieties between which energy transfer is entirely frustrated, leading to the production of reproducible, stable white photo- and electroluminescence.
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We have fabricated transparent white organic light emitting diodes (WOLEDs) for lighting application. The structure property relationship of hybrid WOLEDs has been investigated and optimized devices showed high efficiency. Introduction of transparent cathode of LiF/Al/Ag into the hybrid WOLED led highly efficient WOLED with good transparency.
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Yook, Kyoung-Soo;Jeon, Soon-Ok;Joo, Chul-Woong;Kim, Myung-Seop;Choi, Hong-Seok;Lee, Seok-Jong;Han, Chang-Wook;Tak, Yoon-Heung;Lee, Nam-Yang;Lee, Jun-Yeob 486
High efficiency deep blue and pure white phosphorescent organic light emitting diodes were developed using a new deep blue phosphorescent dopant, tris((3,5-difluoro-4-cyanophenyl)pyridine) iridium (FCNIr). A high quantum efficiency of 9.1 % with a color coordinate of (0.15, 0.16) at 1,000 cd/$m^2$ was obtained in the deep blue device and a high quantum efficiency of 15.2 % with a color coordinate (0.30, 0.32) was obtained in the pure white organic light-emitting diodes. The quantum efficiency of the pure white device is the best quantum efficiency value reported in the pure white device up to now. -
Sung, Chang-Je;Kim, Jun-Jung;Lee, Jae-Man;Choi, Hong-Seok;Han, Chang-Wook;Lee, Nam-Yang;Ahn, Byung-Chul 489
We report white OLED with high color temperature based on simple stacked structure for medical display applications. White OLED was fabricated with two emitting materials of fluorescent blue dopant and phosphorescent yellow dopant. We achieved luminance efficiency of 16.2cd/A and CIE color coordinates of (0.305, 0.317) at 10mA/$cm^2$ . In particular, the correlated color temperature was higher than 7,000K, enough for display applications. -
We report the EL property of blue and blue-violet emitting materials with anthracene moiety as well as a new core structure containing indenopyrazine. Non-doped device using one of indenopyrazine core derivatives was found to exhibit excellent blue-violet color purity of (0.173, 0.063), and narrow emission band of 42nm FWHM. One of anthracene core derivatives with bulky side group also exhibits excellent color coordinates (0.156, 0.088) and an external quantum efficiency of 7.18%.
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The acceptance of electrophoretic display technology as an important alternative to both paper publishing and conventional display readers has now been proven by both the diversity and quantity of new products on the market. The current E Ink display performance as well as the recent advances in this technology will be discussed.
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Electrophoretic displays (EPDs) are attracting considerable attentions as a paper-like display. Especially, Electrophoretic cell consists of micron-sized, charged particles dispersed in a viscous fluid. When an external electric field is applied, the charged particles move with a speed proportional to the particle mobility and the local field strength. In electrophoretic displays fast switching times are required, so knowing the particle mobility is very important. In this paper, we study a novel simulation for calculating the particle motions submerged in a viscous fluid for horizontal switching electrophoretic cell.
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We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and
${\pi}$ -twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time. -
The super multi-view (SMV) display and the high-density directional (HDD) display were proposed as a natural 3D display that is free from the visual fatigue caused by the accommodation-vergence conflict and provides smooth motion parallax. The multi-projection system, the flat-panel system, and the time-multiplexing system are used to construct the HDD displays. The recent progress of the HDD 3D display is reviewed.
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In this presentation, the speaker draws upon his years of research into volumetric display systems. Key content from several books is used as a basis to discuss current activity and to provide a basis for discussion on the next generation of volumetric technologies.
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A volumetric 3D display system based on a rotating two dimensional color LED array is set up. It has a cylinder display space
${\Phi}800{\times}640mm3$ which is composed of 256 slices of pictures in one 3D image with each slice$320{\times}256$ LED pixels. The volumetric image has 4 gray scales and 64 colors. The main structure and working principle of the system is described in detail. -
The cross-talk, which occurs due to the phosphor decay time, is a critical problem in the 3D PDP TV. First, we investigated the factors that affected the cross-talk in waveforms. After the investigation, we designed the driving waveforms for the 3D PDP TV. We also obtained a better result by controlling the driving timing of 3D active glasses.
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We fabricated thin film polarizer by coating lyotropic chromonic liquid crystals (LCLCs) dissolved in anionic monomer solution. Compared to water-based technique, the new method provided many advantages such as excellent coatability, good adhesion to various substrates, and superb surface hardness.
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The drive towards lowering costs and increasing frame rates results in new panel designs and thereby new photomasks designs. One common way to reduce cost is to reduce the number of production steps. For this multi tone photomasks (MTM) are needed. MTMs contain more information and increases photomask placement requirements. Increasing frame rates lead to shrinking geometries. The combination of HTM and shrinking geometries drastically increases the requirements imposed on the pattern generators used to print the photomasks. New methods are therefore needed to enable future photomask manufacturing. This paper introduces three advanced image quality enhancing methods.
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The effects of In and Ga contents on characteristics of InGaZnO (IGZO) films grown by a sol-gel method and their thin film transistors (TFTs) have been investigated. Excess In incorporation into IGZO enhances the field effect mobilities of the TFTs due to the increase in conducting path ways, and decreases the grain size and the surface roughness of the films because more
$InO_2^-$ ions induce cubic stacking faults with IGZO. Ga incorporation into results in decrease in carrier concentration of films and off-current of TFTs since Ga ion forms stronger chemical bonds with oxygen than Zn and In ions, acting as a carrier killer. -
We report on the fabrication of ZnO-based dual gate (DG) thin-film transistors (TFTs) with 20 nm-thick
$Al_2O_3$ for both top and bottom dielectrics, which were deposited by atomic layer deposition on glass substrates at$200^{\circ}C$ . Whether top or bottom gate is biased for sweep, our TFT almost symmetrically operates under a low voltage of 5 V showing a field mobility of ~0.4$cm^2/V{\cdot}s$ along with the on/off ratio of$5{\times}10^4$ . The threshold voltage of our DG TFT was systematically controlled from 0.5 to 2.0 V by varying counter gate input from +5 to -2 V. -
We've studied the optical and electrical properties of amorphous indium gallium zinc oxide thin-film transistor (a-IGZO TFT). When the a-IGZO TFT was illuminated at a wavelength of 660 nm, the offstate drain current was slightly increased, while below 550 nm it was increased significantly. The a-IGZO TFT was extremely sensitive, with deep-level defects at approximately 2.25 eV near the midgap.
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We have fabricated solution-processed zinc-tin oxide thin film transistors (TFTs) and simple circuits on glass substrates. We report a solutionprocessed zinc-tin oxide TFTs on silicon wafer with mobility greater than 9
$cm^2/V{\cdot}s$ (W/L = 100/5${\mu}m$ ) and threshold voltage variation of less than 1 V after bias-stressing. Also, we fabricated solution-processed zinc-tin oxide circuits including inverters and 7-stage ring oscillators fabricated on glass substrates using the developed zinc-tin oxide TFTs. -
We report the improvement in adhesion of IZO thin films through oxygen (
$O_2$ ) plasma treatment of organic polymer film. In conclusion, the$O_2$ plasma treatment of an organic polymer film was accomplished with improving ca. 1.8 times in adhesion than that of the only general etch treatment on the same organic polymer film. -
Phosphorus doped ZnO (PZO) thin films were deposited on
$SiO_2$ /n-Si substrates using DC magnetron sputtering system varying oxygen partial pressures from 0 to 40 % under Ar atmosphere. The deposited films showed reduced n-type conductivity due to the compensating donor effects by phosphorus dopant. The bias-time stability shows relatively good stability over bias and time comparing to un-doped ZnO-based TFTs. -
With injection-type source delivery system of atomic layer deposition (ALD), bottom-contact and bottom-gate thin-film transistors (TFTs) were fabricated with a poly-4-vinyphenol polymeric dielectric for the first time. The properties of the ZnO TFT were greatly influenced by the device structure and the process conditions. The zinc oxide TFTs exhibited a channel mobility of 0.43
$cm^2$ /Vs, a threshold voltage of 0.85 V, a subthreshold slope of 3.30 V/dec, and an on-to-off current ratio of above$10^6$ with solid saturation. -
Kim, Woong-Sun;Moon, Yeon-Keon;Lee, Sih;Kang, Byung-Woo;Kwon, Tae-Seok;Kim, Kyung-Taek;Park, Jong-Wan 546
In this paper, we investigated the effects of different source/drain (S/D) electrode materials in thin film transistors (TFTs) based on indium-gallium-zinc oxide (IGZO) semiconductor. A transfer length and effective resistances between S/D electrodes and amorphous IGZO thin-film transistors were examined. Intrinsic TFT parameters were extracted by the transmission line method (TLM) using a series of TFTs with different channel lengths measured at a low drain voltage. The TFTs fabricated with Cu S/D electrodes showed the lowest contact resistance and transfer length indicating good ohmic characteristics, and good transfer characteristics with a field-effect mobility (${\mu}_{FE}$ ) of 10.0$cm^2$ /Vs. -
Lin, Chia-Sheng;Chen, Ying-Chung;Chang, Ting-Chang;Hsu, Wei-Che;Chen, Shih-Ching;Li, Hung-Wei 550
The negative bias temperature instability on LTPS TFTs in a darkened and an illuminated environment was investigated. Experimental results reveal that the generation of interface state density showed no change between the different NBTI stresses. The degradation of the grain boundary trap under illumination was more significant than for the darkened environment. -
We investigated an application of supramolecular protein, and demonstrated the metal induced lateral crystallization utilizing ferritins with Ni nanoparticles, named the "bio-nano-crystallization". So far, this method has required long time, because of this method condition based on the conventional solid phase crystallization. In this study, we applied the pulsed rapid thermal annealing to bio-nanocrystallization. As a result, we succeeded in the crystallization for a short time. We found that the TFTs characteristics were improved with decrease metal impieties in poly-Si thin films by this method.
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Lee, Youn-Jin;Lee, Kyoung-Min;Hwang, Jae-Dam;No, Kil-Sun;Yoon, Kap-Soo;Yang, Sung-Hoon;Hong, Wan-Shick 557
We attempted modulation of hydrogen dilution ratio to achieve both the minimal incubation layer and high deposition rate. The incubation layer thickness was estimated by transmission electron microscopy (TEM) and crystallization fraction was measured by Raman spectroscopy. -
In this paper, we proposed a simple method of decreasing the off current generated by degradation for improve the electrical characteristics such as mobility and on/off current ratio by making the line patterns on the pentacene surface between the electrodes using atomic force microscope (AFM) lithography.
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We introduce the new modification approaches of photocrosslinkable poly (4-vinylphenol) (PVP) for low hysteresis organic thin film transistors (OTFTs). The dielectric layers were composed of different PVP resin, low molecular melamine, and halogen free photo-initiator. The low hysteresis OTFT from one of the organic gate dielectrics has been realized. The electrical performance of low hysteresis OTFT with photocrosslinkable PVP exhibited a field-effect mobility of 0.2 cm2/Vs, a threshold voltage of - 0.04V, hysteresis of 0.4V.
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Kim, Dong-Woo;Kim, Doo-Hyun;Kim, Keon-Soo;Kim, Hyoung-Jin;Choi, Hong;Lee, Dong-Hyeok;Hong, Mun-Pyo 566
We have examined the silicon nitride ($SiN_x$ ) as gate insulator with the ammonia ($NH_3$ ) plamsa treatment for the soluble derivatives of polythiophene as p-type channel materials of organic thin film transistors (OTFTs). Fabrications of the jetting-processed OTFTs with$SiN_x$ as gate insulator by$NH_3$ plasma treatment can be similar to performance of OTFTs with silicon dioxide ($SiO_2$ ) insulator. -
Octadecyltrichlorosilane (OTS) self-assembled monolayer was selectively patterned by deep ultraviolet exposure, resulting in differential surface state, hydrophilic area with OTS hydrophobic surroundings. High-resolution (<10
${\mu}m$ ) nanoparticulate Ag electrodes and organic semiconductors were patterned from simple dip-casting and ink-jetting on the pre-patterned hydrophilic surface, forming all solution-processed organic thin film transistors. The devices typically have shown a mobility of 0.065$cm^2/V{\cdot}s$ and on-off current ratio of$8{\times}10^5$ . -
Metal oxide/metal bilayer structures are explored as contacts with a low injection barrier in organic thin-film transistors (OTFTs) in an effort to realize their true potential for low-cost electronics. OTFTs with a bilayer electrode of
$WO_3$ (10nm) and Al shows a saturation mobility as large as 0.97$cm^2$ /Vsec which are comparable to those of Au-based control samples (~0.90$cm^2$ /Vsec). Scaling of contact resistance with respect to the thickness of$WO_3$ layer is also discussed. -
Pentacene has excellent semi-conducting characteristics. But pentacene practically used in OTFTs gives rise to problems mainly due to its sensitivity to oxygen and its very low solubility. In order to make up the problems, 6,13-disubstituted pentacene derivatives were synthesized and characterized. The properties of the compounds were characterized by FT-IR, NMR spectroscopy and UV-visible spectrophotometer. Now we are measuring the charge transport mobility and the on/off current ratios.
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This paper reports the electrical characteristics of polyvinylpyrrolidone (PVPy) and the performance of organic thin-film transistors with PVPy as a gate insulator. PVPy shows a dielectric constant of about 3 and contributes to the upright growth of pentacene molecules with 15.3
${\AA}$ interplanar spacing. These results will be discussed. -
Choi, Woo-Seok;Kim, Hae-Yeol;Cho, Hyung-Nyuck;Ryu, Chang-Il;Yoon, Soo-Young;Jang, Yong-Ho;Park, Kwon-Shik;Kim, Binn;Choi, Seung-Chan;Cho, Nam-Wook;Moon, Tae-Woong;Kim, Chang-Dong;Kang, In-Byeong 583
A 14.1" XGA (1024${\times}$ 768) LCD panel with Integrated Black Data Insertion (IBDI) has been world first developed successfully based on the integrated amorphous Silicon TFT gate driver which we previously introduced. The notable features compared with the conventional integrated a-Si TFT gate driver circuit are that the circuit consists of Dual buffer, Carry buffer structure, and Q-node cross charging for stable signal scanning characteristic and prevention of coupling between signal lines. -
Jeong, Ho-Young;Kim, Dong-Sup;Jung, Gang-Seob;Moon, Jong-Won;Lee, Kyung-Ha;Lee, Deuk-Su;Yang, Myung-Su;Ahn, In-Ho;Kang, In-Byeong 587
The mode (reflective and transmissive) switchable LCD has been developed by using a treated SR (Selective Reflector) polarizer. We believe that our approach will be a solution to overcome weak points for a reflective and transflective mode in a dark environment and a transmissive mode in a bright environment. Therefore, this can minimize power consumption, and also be easily fabricated in a current manufacturing process, ready for large sizes. -
In the 2D local dimmable LED backlight system, each LED segment can be controlled separately. This can enhance the contrast ratio and reduce overall power consumption of LCDs. However, an artifact such as 'halo mura' can be observed around the bright object in the dark background. This is caused by the light leakage from the bright area into the dark one. Therefore, the 'halo mura' can be more easily observed in the oblique viewing direction. Thus, in this study, the perceivable degree of the halo mura is evaluated according to the level of the off-axis light leakage of LCDs. It is found that an acceptable degree of halo mura can be obtained in 2.0 cd/
$m^2$ of the diagonal light leakage. In addition, the halo mura is unperceivable under 0.7 cd/$m^2$ of the diagonal light leakage which can be achieved with optimally compensated polarizers. -
Kim, Hong-Sik;Lim, Joo-Soo;Hong, Hyun-Seok;Kwack, Hee-Yong;Ahn, Sung-Hoon;Yu, Sang-Jeon;Shin, Jong-Keun 594
Amorphous silicon nitride (a-SiNx) passivation film as a passivation layer of TFT-LCDs was deposited by AC-reactive sputtering at low temperature. As a result, the electrical characteristics and reliability of TFT with novel passivation showed the same level as the conventional TFT. Finally, we have developed 47"Full HD IPS TFT-LCDs with sputtered amorphous silicon nitride. It is suitable for low temperature based applications such as OTFT and Flexible display. -
Kim, Yeon-Ji;Heo, Hong-Seok;Ko, Jeong-Hoon;Kim, Jin-Ho;Choi, Sang-Ho;Jeon, Il;Hwang, Seong-Han;Lee, Joun-Ho;Kim, Kyeong-Jin;Choi, Hyun-Chul 597
We have developed new type of LCD Device which enables switching from reflective to tranmissive LCD mode and vice versa according to brightness of the surrounding. Alternation in these modes are possible by adding on circular polarized sheet and retardation film onto the bottom polarizer which allows the control of the back light and the LCD cell gamma voltage depending on the atmosphere. This method has been evaluated and confirmed by running on the LCD module device in which we have optimized retardation value by Poincare polarizer analysis. -
Yao, I-An;Chen, Chueh-Ju;Yang, Chiu-Lien;Pang, Jia-Pang;Liao, Shih-Fu;Li, Jia-Hsin;Wu, Jin-Jie 600
The liquid crystal device with switchable dynamic mode and memory mode has been investigated and developed. The proposed device reveals splay,${\pi}$ twist and bend states by selective switching among them. In the dynamic mode, this device is operated in the bend state which exhibits the wide view angle and fast response time properties due to the self-compensated bend structure and flow accelerated fast response time. In the memory mode, the permanent memory characteristics in the splay and${\pi}$ twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed. -
We propose a method to control the pretilt angle of liquid crystal (LC) by doping a proper amount of UV curable reactive mesogen (RM) monomers in hometropic polyimide (PI). The intermediate pretilt angles are produced by anchoring competition between homeotropic PI and the polymerized RM which direction is along the LC molecules under electric field.
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Kim, Jin-Soo;Ahmad, Farzana;Muhammad, Jamil;Park, Sang-Woo;Lee, Jin-Woo;Yun, Hee-Young;Jung, Jae-Eun;Jang, Jae-Eun;Jeon, Young-Jae;Kim, Yong-Bae 607
We present a Brownian molecular dynamics computer simulation method for calculating the rotational viscosity of the liquid crystal mixture comprising pentylcyanobiphenol (5CB) and decylcyanobiphenol (10CB). Mean director of the ensemble has been used as a nematic director. Results show a good agreement with experimental ones [Sudeshna DasGupta et al., Physics Letters A 306(2003)235-242]. -
Jung, Jun-Ho;Ha, Kyung-Su;Chae, Mi-Na;Park, Seul-Ki;Song, Eun-Gyoung;Lee, Myong-Hoon;Jeong, Kwang-Un;Lee, Seung-Hee 610
New rod-disc liquid crystal (LC) molecule RD12 (12 is the number of carbon atoms between the rod and disc mesogenic liquid crystals) was synthesized via the chemical attachment of six cyanobiphenly calamitic mesogens linked to the triphenyl discotic mesogen with six alkyl chain linkage. Aligning characteristics associated with homogenous alignment is investigated at first and then field-dependent molecular reorientation under a vertical electric field is studied. Interestingly, they show abnormal slow molecular transition from initiate state (no electric field condition) to certain voltage. In this condition, we observe the molecular competition during reorientation. However, once a tilting direction of disk molecules are defined, the frustration is not observed anymore. The origin of this phenomenon is explained with a suggested model for the first time. -
Park, Kyung-Ho;Lee, Gak-Seok;Kim, Jae-Chang;Yoon, Tae-Hoon;Kim, Jin-Hwan;Yu, Jae-Ho;Choi, Hwan-Young 614
For the high reflectance under the ambient light condition, a highly efficient diffractive reflector has been proposed, based on a micro grating structure.[1] This reflector was designed to show highly concentrated distribution of the reflected light to the normal direction of the reflector under specific incident conditions of the light. In order to apply a diffractive reflector to a reflective liquid crystal display, the coupling between the viewing angle characteristics of a liquid crystal (LC) cell and the reflective distribution of the reflector should be considered. Under the optimum configuration confirmed through the analysis of the coupling between a LC cell and a reflector, a reflective vertical alignment (VA) cell with a diffractive reflector shows contrast ratio and brightness much higher than that with a conventional bumpy reflector. -
Jung, Jun-Ho;Ha, Kyung-Su;Chae, Mi-Na;Cho, In-Young;Kim, Woo-Il;Kim, Dae-Hyun;Kim, Sung-Min;Lee, Seung-Hee 616
Color tracking behavior of in the fringe-field switching (FFS) mode using a liquid crystal with positive dielectric anisotropy has been studied. In the in-plane switching and vertical alignment devices, color chromaticity at normal direction changes from bluish to yellowish white linearly with increasing grey levels from dark to white state. Interestingly, abnormal behavior in color tracking is observed in FFS devices using a liquid crystal with positive dielectric anisotropy, that is, it changes from bluish to yellowish up to a certain middle grey level but turns over to bluish white with further increasing from a grey level to a fully white state. In this paper, we analyze this abnormal effect from the calculated and experimental results. -
We demonstrated a liquid crystal display (LCD) mode with a single polarizer based on the array of a switchable microlens consisting of a circular stop mask and its complementary open mask. The focused beam passed through the open mask and thus the bright state was obtained, while the defocused beam was blocked by the stop mask and the complementary open mask. It is expected that our single-polarizer LCD mode is applicable to low cost displays.
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Photo polymerization-induced Hybrid Alignment of Nematic Liquid Crystal for Roll to Roll FabricationHere we report a photo polymerization-induced hybrid alignment of a nematic liquid crystal cell which can be applied for a roll to roll fabrication process. Predominant polymerization in the vicinity of UV incident front induced a diffusion of monomers toward front slide and anisotropic polymer network was formed parallel to the polarization direction of the UV light. This induced planar alignment of liquid crystals at the front slide. Simultaneously, homeotropic alignment was induced at the bottom slide as the polymers are phase-separated from a bottom slide.
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Jhun, Chul-Gyu;Jung, Un-Sung;Moon, Jin-Hyouck;Kim, Kyoung-Sun;Lee, Ji-Hoon;Kwon, Soon-Bum;Lee, Joong-Ha;Kim, Jae-Chang 625
In the bistable chiral splay nematic (BCSN) mode, the splay and${\pi}$ twist states are used for the two stable states. The switching property is strongly dependent on the amplitude of the electric field. In this paper, we investigated the gray scale capability of BCSN liquid crystal display (LCD) by the gradual horizontal electric field caused the interdigital electrode of by the inequality gap. We demonstrate the gray scale of the BCSN LCD during transition process under the horizontal electric field. -
Kim, Jin-Ho;Lim, Young-Jin;Her, Jung-Hwa;Srivastava, Anoop Kumar;Park, Kyoung-Ho;Lee, Joun-Ho;Kim, Byeong-Koo;Lee, Seung-Hee 629
We have proposed a novel viewing angle controllable display of in-plane switching (IPS) mode with single panel. One pixel of this device is divided to two regions, in which main pixel shows image and sub pixel for viewing angle control. In initial state, the liquid crystal of sub pixel is homogeneous aligned on substrate for wide viewing angle mode. On the other hand, after applying voltage, the liquid crystal of sub pixel tilts up for narrow viewing angle mode. The proposed device has advantage for the function for simple manufacturing process and good viewing angle control with single panel. -
Synthesis and Properties of Polyesters with Bent-Shaped Mesogens Containing Naphthalene Central UnitNew polyesters with bent-shaped mesogens were synthesized varying the central unit with 1,6- and 2,3- naphthylenes, and introducing the dodecamethylene flexible spacer. The mesogenic properties of the polymers were characterized by FT-IR spectroscopy, DSC, polarizing optical microscopy.
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Kim, Min-Su;Kim, Mi-Young;Kang, Byeong-Gyun;Kim, Mi-Kyung;Yoon, Su-Kin;Choi, Suk-Won;Lee, Gi-Dong;Lee, Seung-Hee 637
The LCD based on Kerr effect is highly interesting because it uses an optically isotropic state with no need of alignment layer and it shows sub-millisecond response time. The problem of the device is that it requires very high operating voltage and the transmittance is relatively low compared with other LCDs that use nematic LC. In this work, we study on various electrode structures and driving method which can lower operating voltage. -
We demonstrated a solvent-assisted soft-lithographic patterning method for producing patterned structure and patterned ordering with lyotropic liquid crystalline polymer (LCP) film. Experimental results showed that the liquid crystalline ordering of lyotropic film could be controlled by shearing effects of the fluidic solvent though the patterned mold channels. In this work, two types of lyotropic LCPs were used to investigate the effects of the alkyl chain length of the lyotropic LCP on producing liquid crystalline ordering through the solvent-assisted fluidic patterning.
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We investigated vertical liquid crystal (LC) alignment effects of a self-assembled-monolayer (SAM) prepared on an anisotropic
$SiO_2$ surface where the field-induced LC reorientation produced a uniform single domain texture. We compared the results with the homeotropic-to-random planar reorientation results shown in LCs aligned on a SAM surface prepared on an isotropic$SiO_2$ surface. -
We investigate nematic liquid crystal (NLC) alignment on ion-beam exposed ZnO films. ZnO is optically transparent material in the visible range. We optimized the deposition parameters such as deposition temperature and gas ratio for high transmittance and resistivity. Using ion-beam treated ZnO films, LC cells are fabricated and the conditions such as exposure energy and time for uniform alignment are found. The NLC molecules align parallel to the ion-beam exposure direction. The electro-optic and response characteristics show the possibility of application of this method in liquid crystal display.
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Novel compounds with rod and disc mesogens were synthesized and characterized. The molecular structures were confirmed by FT-IR,
$^1H$ -NMR spectroscopy and elemental analysis. The optical properties of these molecules were investigated by UV-vis absorption spectroscopy and photo-luminescence spectroscopy. We found that they are a novel series of blue light-emitting molecules. The absorption spectra peaks of these compounds varied from 336 nm-341 nm, while the maximum emissions centered form 410 nm-450 nm in chloroform solution. However, unexpectedly we could not found their biaxiality and mesomorphic properties by POM, conoscopy and DSC method. -
Here we report a nano-sized polymer-dispersed liquid crystal (NPDLC) with an excellent scattering effect due to the maximized Mie scattering. We used a modified emulsification method combined with a limited coalescence mechanism. The fabrication process is simpler to obtain uniform nano-sized droplets rather than the conventional polymerizationinduced phase separation method.
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Optically compensated bend (OCB) mode has intrinsic characteristics such as wide viewing angle and fast response time. However, in order to operate the OCB mode in bend state, this device needs quick transitions from the initial splay state to bend state. In this paper, we proposed OCB mode with initially bend state using reactive mesogen (RM) monomer for surface polymer stabilization. The device shows continuous reorientation of the LC with applied field and a very fast response time.
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This paper describes a fabrication method for high transmittance panel using newly designed polarizer and liquid crystal with a high dielectric anisotropy (
${\Delta}{\varepsilon}$ ). To enhance the transmittance of the panel without contrast ratio reduction, new polarizer with high transmittance and high${\Delta}{\varepsilon}$ liquid crystal were used. The transmittance of the liquid crystal display (LCD) panel employed by a new polarizer was increased by 6% over that of the panel with a conventional polarizer and liquid crystal in LCD industry. -
We would like to show a measuring technique of azimuthal anchoring energy of the nematic liquid crystals. The electro-optical setup of liquid crystal cell, crossed polarizers and magnetic field was assumed. The planar or hybrid alignment cells were prepared. The director in the light entering substrate and the polarization of light was adjusted into parallel to the magnetic field. The director orientation of exit substrate and analyser maintained perpendicular to the magnetic field. As the magnetic field strength is increased, the director deviates from the easy axis and rotates to the field direction. We obtained an equation calculating the change of transmission with the field and measured experimentally the transmission. By comparing the calculating and experimental data, we obtained the azimuthal anchoring strength.
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Photosensitive polyimide containing methoxy cinnamate derivatives as a photo-alignment layer is investigated. The anisotropy of alignment layer was induced by irradiation linearly polarized UV (LPUV). We studied the effect of the methoxy cinnamate groups on alignment LCs.
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Polymide is widely used alignment material of recent commercial LCD panel structure. Generally, polyimide alignment material is classified soluble polyimide type and polyamic acid type with their main bond structure of solution state. specially, compared to polyamic acid alignment layer, soluble polyimide type alignment layer have excellent reliability during long term LCD driving cause of their high imidazation ratio(%), high voltage holding ratio(%) and low ion density. The other side, this type alignment materials has significant DC image stickicng side effect for using in-plane switching mode lcd structure cause of their slow DC discharging property. we applied inorganic salt to usual soluble polyimide type alignment layer and found out this technique had good DC image sticking property without any loss of reliability property in inplane switching LCD cell structure. This approach leads excellent DC image sticking property with maintaining high reliability property this approach confirmed improves an image sticking and a reliability simultaneously from the horizontality aligned LCD mode whose relatively bad image sticking property.
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Lim, Young-Nam;Lee, Tae-Rim;Park, Byoung-Gyu;Roh, Seung-Kwang;Kim, Hyun-Chul;Kim, Hyun-Seung;Kim, Kyeong-Jin;Shin, Hyun-Ho 677
DC influence between pixel electrode and alignment layer (AL) in in-plane switching mode LCD was analyzed through DC equivalence-circuit equation induction, DC charge-discharge simulation, luminance and residual-DC measurement systems using test patterned (TP) cell. DC discharging rate (DDR) of single layer electrode was faster than that of double layer electrode and DDR of low resistance AL was faster than that of high resistance AL. DC discharging characteristics had a close relation to layer number and resistance between two electrodes. -
We fabricated a stressed liquid crystal cell by mixing liquid crystal with a photo-polymer. By carefully choosing the mixing ratio between liquid crystal and the polymer, and by suitable mechanical shearing of the substrates, we demonstrated feasible electro optical properties for displays.
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We report inverted white OLEDs fabricated by full wet processes. We utilized inverted structure OLEDs since the structure was better for the realization of full wet fabrication of OLEDs. It was found that the performance of inverted OLEDs is comparable to that of conventional OLEDs. In this presentation, we will discuss in detail a few important issues on the full wet fabrication of OLEDs.
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It has been recently reported that nano-sized MgO single crystal powders emit ultraviolet by stimulation of electrons under vacuum condition. Therefore, in this study, nano-crystalline MgO powders were applied to a xenon plasma flat fluorescent lamp for LCD backlight to improve emission efficiency of the lamp by help of extra ultraviolet from nano-MgO. For comparison with nano-crystalline MgO powders, MgO nano-thin film was applied directly on phosphors inside a lamp panel through e-beam evaporation The luminance and efficiency of FFL with an addition of MgO nano-crystal powders on phosphors were improved by around 20%. Application of MgO thin film to phosphors worsened the emission characteristics of FFLs, even rather than FFL without MgO. The reason came from insufficient stimulation of phosphors by UV, crystallinity of MgO, and low secondary electron coefficient.
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Screen printable CNT pastes were formulated including conductive nano particles (CNPs) and their properties were investigated with an expectation of stable cold cathodes for advanced lamp application. CNT cathodes showed a turn-on field of 1~1.5V/um, a life time of ~100 hours at an emission current density of 10uA/
$cm^2$ for DC-bias. Detailed analysis of measured I-V was carried out by applying Fowler-Nordheim model to trace down the origin of emission property degradation. -
The ray-tracing technique was used to optimize the light guide plate for the purpose of improving the on-axis luminance on the edge-lit backlights. One-dimensional prisms and engraved V-shaped patterns were applied to the upper and the lower surfaces of the light guide plate, respectively. By optimizing the apex angles of these micro-structures, as well as the shape of the reverseprism film put over the light guide plate, highly-collimated light-output distribution could be obtained on the backlight, which may contribute to the development of mobile LCD's with low power consumption.
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Optical properties of white organic light-emitting devices (WOLEDs) fabricated utilizing a phosphor layer acting as a color conversion layer were investigated. The WOLEDs were achieved due to the enhancement in the color conversion efficiency of the phosphor layer, and the chromaticity coordinates of WOLEDs were (0.29, 0.33).
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We present the epitaxial growth of high-quality ZnO layers by chemical vapor transport (CVT) technique on (01-12) sapphire with a ZnO buffer layer growth by metal-organic chemical vapor deposition (MOCVD). The surface of the grown ZnO epitaxial layers has atomically flats and the RMS is 0.11 nm. PL spectrum of as-grown samples exhibits two emissions originated by interactions between photon and free excitons.
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The external electrode fluorescent lamp(EEFL) has recently been applied to backlight of LCD TV as a new light source. The dependence of the electro-optic characteristics of the EEFL used in direct-lit backlights on the glass thickness was examined in detail, and the ultraviolet(UV)-light efficiency was estimated. It was found that the lamp efficiency became larger as the glass thickness decreased if other conditions were the same.
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As the inner diameter of CCFL is increased in the range of outer diameters 3~5 mm, the luminance efficiency is increased by the low power consumption. For the outer diameter 5 mm, the efficiency is linearly increased even at the range of a high current.
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The fabrication of micro-scale irregular holes by using PMMA (Poly Methyl Methacrylate) beads in the front dielectric layer was proposed to improve luminous efficacy of an ac plasma display panel. Through the firing process of front dielectric layer, bowl shaped holes with a depth of
$2.5{\mu}m$ , a top diameter of$8-12{\mu}m$ , and a bottom diameter of$4-7{\mu}m$ were fabricated. The proposed ac plasma display panel with the irregular micro-scale holes improved the luminous efficacy by 18 % due to the decrease in the minimum sustain voltage. -
Preferred orientation of MgO protection layer is controlled via adjusting diffusion of adatom between (111) plane with highest neighbor atoms and (200) plane with lowest neighbor atoms. The diffusion of adatom could be modulated by the factors such as substrate temperature, deposition rate, and extra energy applied on adatom like ion beam energy.
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The effects of the temporal dark image sticking phenomena on bright screen were investigated with various He, Ne contents and a high Xe content fixed at 11% in the 50-in. ac-PDPs. In this work, the disappearance time and the display luminance between the before and after discharge in the discharge and non-discharge regions were measured with 0%, 35%, and 50% He contents. Consequently, the temporal dark image sticking on bright screen was reduced with the increase of He contents compared with the non-He (0%) content.
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We suggest a new approach to lower the operating voltage of plasma display devices using a piezoelectric transformer (PT).
$Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ (PMNT) was used as a piezoelectric material. The Rosen-type PT, with a compact size of 10 mm${\times}$ 20 mm${\times}$ 0.3 mm, was fabricated on a glass substrate. The fabricated PT was operated as a half-wave vibration mode at around 80~90 kHz. The maximum voltage step-up ratio was 3 at 87.8 kHz when the input voltage was 10.32 V (peak-to-peak). -
Nam, Hyung-Woo;Choi, Yong-Suk;Bae, Hyo-Won;Kim, Yun-Gi;Ok, Jung-Woo;Kim, Dong-Hyun;Lee, Ho-Jun;Lee, Hae-June;Park, Chung-Hoo 721
In this paper, we proposed fence electrode structures. The experimental structures change cross-bar length as 145, 105, 65 and$30{\mu}m$ to improve the electro-optical characteristics. The proposed structures improve the addressing time and luminous efficacy compared with the T145 structure which has the cross-bar length of$145{\mu}m$ as the reference. Especially, in the case of the T30 structure with cross-bar length of$30{\mu}m$ , it gains lower power consumption by 34%, and higher luminous efficacy by 20% than those of the reference structure. -
Lowering the dielectric constant is one of the important issues for the efficiency and the power consumption in the plasma display panel (PDP) industry. This study examined the effect of the addition of ceramic filler (up to 10% of crystalline and amorphous silica, respectively) to a
$B_2O_3$ -ZnO-$P_2O_5$ glass matrix on the dielectric, coefficient of thermal expansion, etching behaviors and residual stress for the barrier ribs in plasma display panels. The dielectric constant of barrier ribs is affected by containing two types of$SiO_2$ filler for the barrier rib composition in PDP. -
A negative waveform having inverted polarity of conventional waveform during reset and sustain periods was proposed to improve the driving characteristics. In order to control the negative wall-charge distribution, a positive bias on the scan electrode was applied during reset period. Compared to 0 V scan-bias condition, at 8 V scan-bias the formative time lag was improved about 23.95 % and the average time lag was improved about 14.91 %. All experiments were performed with the 42-inch PDP module in XGA resolution.
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Kim, Hyun-Gyu;Lee, Ho-Jun;Kim, Dong-Hyun;Park, Chung-Hoo;Cho, Sung-Yong;Ha, Chang-Seung;Wi, Sung-Suk;Sim, Choung-Hwan;Lee, Hae-June 732
In this paper, high Xe(Ne+Xe 10%, 20%, 30%) AC-PDP's discharge characteristics according to aging time were studied. The static margin, Vt close curve, discharge time lag was measured for experiments. According to increase of Xe partial pressure, the static margin and luminance was increased. As the result of analysis for misfiring probability, the misfiring is frequently occurred in accordance with increasing of aging time. To improve misfiring, we proposed 3Reset waveform and achieved misfiring probability which was improved. -
Son, Chang-Gil;Han, Young-Gyu;Kim, Yong-Hee;Cho, Byeong-Seong;Hong, Young-Jun;Song, Ki-Baek;Bae, Young-Joo;Kim, In-Tae;Choi, Eun-Ha 736
We have studied that the secondary electron emission characteristics of functional layers which have different kinds of MgO sub-micrometer size powder in AC-PDP. We used cathodoluminescence(CL) and gamma focused ion beam (${\gamma}$ -FIB) system for measurement of secondary electron emission characteristics. Also we made 6 inch test panel which applied functional layers for evaluation of discharge characteristics. -
In this paper we proposed a new electrode design to get an enhanced luminous efficiency in AC PDP. The width and shape of the TTO electrode were varied, and the electro-optical properties such as luminance, power consumption, luminous efficiency were estimated with the variation of frequency, duty ratio and applied voltage. The discharge characteristics were investigated to explain the effect of the new electrode structure on the electro-optical properties.
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Plasma Display Panels (PDPs) have illustrated impressive results in terms of light emission efficiency of the Ne-Xe mixture compared with the He-Xe mixture. However, He-Xe has shown to achieve superior color purity. This paper presents the optimization of excitation efficiency and color purity for He-Ne-Xe ternary gas mixtures. Furthermore, we investigate the effect that a protective dielectric layer has on UV photon efficiency in a matrix known as electrode type PDP.
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This paper provides a novel scheme to enhance luminous efficiency within Plasma Display Panels (PDPs). The He-Xe or Ne-Xe mixtures are mainly used in conventional PDP cells, where their discharge characteristics exemplify different behavior. Significantly, the excitation efficiency in He-Xe is lower than that of the Ne-Xe mixture. This paper demonstrates that by adding a small quantity of Ar or Kr gas in Ne-Xe mixture increases cell efficiency, while for the He-Xe mixtures their cell efficiency is reduced.
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High efficiency white organic light emitting diodes were fabricated by using an alignment free mask patterning method. Only red/green emission without any blue emission was observed in the red/green patterned region and blue emission was emitted in other area. A combination of the red/green and blue emission gave a high efficiency white emission. A maximum current efficiency of 30.7 cd/A and a current efficiency of 25.9 cd/A at 1000 cd/
$m^2$ were obtained with a color coordinate of (0.38, 0.45). -
We developed a novel patterning method of organic light emitting materials using a laser-inscribed sacrificial layer for fabricating high-resolution pixels in organic light emitting displays (OLEDs). Our patterning process is capable of achieving high spatial resolution of about 10
${\mu}m$ . Moreover, it has no detrimental effect on the electrical properties of organic materials. This patterning approach is expected to be applicable for patterning and integrating a wide range of organic materials for organic electronic and optoelectronic devices. -
Kim, Young-Kook;Hwang, Seok-Hwan;Kwak, Yoon-Hyun;Lee, Chang-Ho;Yi, Jeoung-In;Lee, Jong-Hyuk;Kim, Sung-Chul 758
The electroluminescent devices with the phenylnaphthyldiamine HTMs as the hole-transporting layer were more efficient than that with the biphenyldiamine HTM 1. Particularly, the life-time of the device IV using HTM 2 is about two times longer than that of the reference device III with HTM 1 within the measured current density, indicating more effective recombination at the emitting layer of device IV. -
We have synthesized and demonstrated a red emission in Organic Light Emitting Diodes (OLEDs) using phosphorescent iridium(III) complexes based on the 2-phenylpyridine ligands with electron-withdrawing carbonyl groups. Among those, a device exhibited highly efficient red-orange emission with the luminance of 20460 cd/
$m^2$ at 12 V, the luminous efficiency of 22.0 cd/A at 20 mA/$cm^2$ , and the$CIE_{x,y}$ coordinates of (x=0.560, y=0.439 ) at 10 V. -
We synthesized a spirobenzofluorene type phosphine oxide (SPPO2) as a new triplet host and an universal electron transport material for phosphorescent organic light-emitting diodes(PHOLEDs). Red PHOLEDs with the SPPO2 host material showed a high quantum efficiency of 14.3 % with a current efficiency of 20.4 cd/A. In addition, the SPPO2 could be applied as an electron transport material which can be matched with any host material due to the lowest unoccupied molecular orbital of 2.4 eV. Electron injection from a cathode to the SPPO2 electron transport layer was better than common electron transport materials. In particular, the SPPO2 was effective as the electron transport material in blue PHOLEDs and the quantum efficiency was more than doubled and driving voltage was lowered by more than 3 V using the SPPO2 instead of common electron transport material.
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Choi, Sung-Hoon;Kim, Sang-Dae;Han, Kyu-Il;Lee, Se-Hee;Park, Eun-Jung;Kum, Tae-Il;Jung, Young-Kwan;Lee, Seok-Jong;Lee, Nam-Yang 771
The Improved stability of organic light emitting diodes (OLEDs) containing lithium-quinolate (Liq) as the ETL doping material is investigated. The lifetime could be improved by threefold using the Liq-doped ETL structure. The improvement was attributed to the Liq-doped ETL, which improved hole-electron balance and has a good electrical stability. Additionally, when the Liq doped device was combined with an Mg/Al cathode, the OLED produced a longer lifetime than other device. -
Park, Jeong-Keun;Lee, Kum-Hee;Kim, Seul-Ong;Park, Jung-Sun;Seo, Ji-Hoon;Kim, Young-Kwan;Yoon, Seung-Soo 775
Novel blue host material, 4,4'-(dinaphthalen-2-yl)-1,1'-binaphthyl (DNBN), was designed and synthesized for OLEDs. In order to test the electroluminescent properties of DNBN, DNBN was used as the host materials for a blue emitter, PCVtPh. The device exhibited deep-blue emission with the CIEx,y coordinates (x=0.15, y=0.08) at 8.0 V, a luminous efficiency of 1.66 cd/A, a power efficiency of 0.77 lm/W and an external quantum efficiency of 2.30 % at 20 mA/$cm^2$ , respectively. -
New inverted architecture of a hybrid inorganic-organic light-emitting diode, utilizing ZrO2 electron-injecting layer, is presented. The thickness of the ZrO2, as well as the annealing of the light-emitting polymer, is found critical to obtain good performance. A range of light-emitting polymers is shown to operate efficiently in the proposed architecture.
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Choi, Mi-Ri;Han, Tae-Hee;Woo, Seong-Hoon;Lim, Kyung-Geun;Yun, Won-Min;Kwon, Oh-Kwan;Park, Chan-Eon;Shin, Hoon-Kyu;Hur, Dal-Ho;Shin, Kyoung-Hwan;Jang, Jyong-Sik;Lee, Tae-Woo 781
We achieved high efficiency and long lifetime in small-molecule organic light-emitting diodes using a blend of polyaniline-based conducting polymer and a perfluorinated ionomer as a hole injection layer (HIL). The HIL formed by single spin coating greatly enhanced the surface work function and thus the hole injection from the anode, which resulted in great improvement in device luminous efficiency. We find that the solution processed HIL outperforms the conventional vacuum-deposited small molecule HIL in terms of the device performance. -
Thermal transfer of emitting layer from the donor film to the substrates depends on the physical interaction between the donor film, the emitting layer, and the hole-transport layer (HTL). The interfacial adhesion between the donor film and the EML, the cohesive force of the EML, and the interfacial adhesion between the EML and the HIL have to be optimized to achieve good LITI pattern quality. It was found that surface pretreatment of the donor plate was important on the laser induced thermal transfer of the emitting layer onto the HIL layer of the OLED devices.
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High contrast red, green and blue organic light-emitting diodes were fabricated using inorganic metal multi layer composed of thin Al, KCl and thick Al and then were compared to optical and electrical characteristics with the attached polarizer and conventional OLEDs. Ambient light reflection of OLED using inorganic metal layer, polarizer and conventional metal layer were 29.2, 31.1 and 82.5% respectively. Optical characteristics of OLEDs using inorganic metal layer were max luminescence of 13040 cd/m2 and luminous efficiency of 2.12 cd/A at 8V whereas OLEDs using polarizer has 8456 cd/m2 and 1.43 cd/A at 8V each. OLEDs including inorganic metal multi layers show significant technical advantages in achieving high performance of OLED display with improved contrast ratio of 251:1, specifically in Red OLED.
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Lee, Ho-Jae;Yu, Eun-Sun;Jung, Sung-Hyun;Kim, Hyung-Sun;Kang, Eui-Su;Chae, Mi-Young;Chang, Tu-Won 791
We have developed novel small molecular materials for solution phosphorescent OLEDs having multilayered device structures. These novel materials are applied as an interlayer which is between a buffer layer (or hole injection layer) and an emitting layer to improve the luminance efficiency of solution green phosphorescent OLEDs. In order to form stable double layers by spincoating process, we take the advantage of solubility differences of interlayer materials and emitting materials. Using CIM3 as an interlayer, we have attained the best luminance efficiency, 36 cd/A at a given constant of 2000cd/$m^2$ in the structure of ITO/PEDOT:PSS/CIM3/CIM6:Ir(mppy)$_3$ /BAlq/Alq$_3$ /LiF/Al. -
Kim, Jae-Hyun;Seo, Jun-Seon;Hong, Seok-Min;Kang, Byoung-Ho;Kim, Do-Eok;Lee, Sung-Youp;Shin, Byong-Wook;Lee, Hyeong-Rag;Kim, Hak-Rin;Kang, Shin-Won 794
We manufactured a novel gas permeation thin film passivation by using inorganic Mg-Zn-F target which has better optical characteristics and high electronegativity. We fabricated targets in various composition ratio and formed about 200nm which is limited thickness of the flexible display. Applied to PLED device, the target which composed of$MgF_2$ and Zn at the ratio of 4:6, WVTR was reached the measurement limit of the equipment,$10^{-3}g/m^2{\cdot}day$ and the life time was increased 25 times better than PLED device which is non-passivation. -
New blue emitting materials of o,p-TP-EPY and m,m-TP-EPY were synthesized using two terphenyl units with different structures in the new core of indenopyrazine. EL spectrum of o,p-TP-EPY was more blue shifted than m,m-TP-EPY, and external quantum efficiency of o,p-TP-EPY was showed improvement of about 60% compared to efficiency of m,m-TP-EPY.
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Jou, Jwo-Huei;Lin, Cheng-Wei;Lai, I-Ming;Wang, Wei-Ben;Chiu, Chuan-Huan;Grigalevicius, Saulius;Wu, Chung-Chih 803
A highly efficient blue organic light-emitting diode (OLED) was fabricated by using a novel polymer host, poly[3-(carbazol-9-ylmethyl)-3-methyloxetane]. The resultant solution-processed device showed a markedly high efficiency of 29.7 lm/W at 100 cd/$m^2$ by doping 24 wt% blue dye bis(3,5-difluoro-2-(2-pyridyl)-phenyl-(2-carboxy pyridyl) iridium (III). -
Epoxy functionalized organic-inorganic hybrid materials (hybrimers) were synthesized by sol-gel reaction for application in OLED barrier coating. By using the calcium degradation method, the oxygen transition rate (OTR) and water vapor transition rate (WVTR) measured so far is
$10^{-2}cc/m^2$ -day for oxygen and$10^{-1}g/m^2$ -day for water molecules with single hybrimer coating film, respectively. Encapsulated OLED devices have life time of 14hrs of a single hybrimer barrier coating and 29hrs of hybrimer/inorganic double barrier coatings at$25^{\circ}C$ and 60% relative humidity. -
Fluorene derivatives are well-known in the polymer OLEDs due to their good charge carrying property. In this work, we synthesized a series of conjugated copolymers based fluorene derivative and phenylamine units by using Buchwald-Hartwig reaction in order to investigate their photoreactivities and use as the HIL/HTL layers of OLEDs using solution processes.
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We have investigated the effect of host on the device charactistics of green phosphorescent organic light emitting devices consising of mCP, CBP and TPBi. Electrons were confined within the device by inserting hole transport layer between the electro transport and the emitting layer. When the appropriate interlayers were added, the device with TPBI host layer performances were found to be dramatically enhanced, with current efficiency and lifetime of 18cd/A and 18hour.
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We have developed highly efficient blue phosphorescent organic light-emitting devices (PHOLEDs) with simplified architectures using new host materials. The Blue PHOLED with new host:FIrpic emitting layer exhibits a maximum luminance efficiency of 34 cd/A and a low operating voltage 5 V at a high luminance of 1212 cd/
$m^2$ . -
Tandem white organic light emitting diodes (WOLEDs) are fabricated by using a transparent interconnecting layer of Al:LiF composite/molybdenum oxides (
$MoO_3$ ). We demonstrate two types of tandem WOLEDs consisting of two color emissions (red and blue emission) and three color emissions (red, green and blue emission). Tandem WOLED consisting of three color emission shows higher external quantum efficiency and current efficiency. -
We present multilayer transparent electrodes (MTEs) that resulted in organic light-emitting diodes (OLEDs) with the 90 % higher forward luminous efficiency and 30% higher external quantum efficiency (EQE) than conventional ITO based devices respectively. Optimization method of such MTE structure is investigated in consideration of both injection and optical structure.
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The authors report on the fabrication of p-type depletion mode inverter that composed of two pentacene based thin-film transistors (TFTs) on several dielectric surfaces. We use shift of threshold voltage depends on pentacene-thickness.
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We report the synthesis and electroluminescent properties of new aromatic compounds as emitting materials based on indenopyrazine, such 2,8-bis(3,5-diphenylphenyl)-6,6,12,12-tetraethyl-6,12-dihydrodiindeno[1,2-b:1',2'-e]pyrazine (DPP-EPY) and 2,8-bis(3',5'-diphenylbiphenyl-4-yl)-6,6,12,12-tetraethyl-6,12-dihydrodiindeno[1,2-b:1',2'-e]pyrazine (DPBPEPY). DPP-EPY showed high thermal stability, narrow FWHM of 46 nm, luminous efficiency of 1.04 cd/A at current density of 10 mA/
$cm^2$ and CIE coordinate of (0.161, 0.104). -
We investigated the device performance for organic light-emitting characteristics based on the electron-injecting interfacial characteristics of Ba deposited on tris(8-quinolinolato)aluminum (III) (
$Alq_3$ ) with a change of a Ba coverage. The device performance of organic light-emitting diodes with Ba coverage of 1 nm significantly improved by the lowering of the electron-injecting barrier height that was induced by electronic charge transfer. However, the device with Ba coverage above 1 nm showed poor device performance. The spectroscopic results indicated that the$Alq_3$ molecules started to decompose by the reaction between Ba and the phenoxide moiety of the molecule. -
In this work, pyromellitic dianhydride (PMDA) was used as a cathode interfacial layer in the organic light emitting diodes (OLEDs) and its thickness was optimized. Various electrical and optical characterizations of the OLEDs having various thicknesses of the PMDA cathode interfacial layer revealed that the best OLED performance could be achieved by using 0.5 nm-thick PMDA layer compared to the control device without any interfacial layer.
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In this paper, chalcogenide glasses material(Se, Te, Sb) is firstly used as encapsulation layer of OLEDs under high vacuum of
$10^{-4}$ Pa. In the experiments, properties of OLEDs encapsulated by Se, Te, Sb thin film is compared with that of device encapsulated by traditional method. It is found that Se, Te, Sb film can extend lifetime of devices to 1.4, 2, 1.3 times respectively. Chalcogenide glasses film as encapsulation layer has little effect on some characteristics of device. The research indicated that OLEDs can be well protected upon applying Se, Te, Sb film as encapsulation layer. It is clear that it can prolong the lifetime obviously. -
Jung, Choong-Hwa;Park, Moo-Jin;Eom, Jae-Hoon;Shim, Hong-Ku;Lee, Seong-Taek;Yang, Nam-Choul;Liand, Duan;Suh, Min-Chul;Chin, Byung-Doo;Hwang, Do-Hoon 843
A polymeric host for triplet emitters composed of N-alkylcarbazole and tetramethylbenzene units was successfully synthesized. Efficient energy transfer was observed between this polymeric host and green phosphorescent dyes. The device fabricated using 5 wt% green 1 in the polymeric host as the emitting layer showed the best performance. Thin films of this host-guest system, exhibiting clear stripe patterns could be prepared through the LITI process. The patterned films were then used to fabricate electrophosphorescent devices, which show performance characteristics similar to those of spin-coated devices. The new host material is a good candidate to be used in polymer-based full-color electrophosphorescent light-emitting displays. -
Seo, Jun-Seon;Kim, Jae-Hyun;Hong, Seok-Min;Kang, Byoung-Ho;Kim, Do-Eok;Kim, Hak-Rin;Kang, Shin-Won 846
In this study, we manufactured polymer-LED using light emitting copolymer as the active layer. After cathode layer deposition, we did post-annealing at$150^{\circ}C$ during 10 min in$N_2$ glove box. Then, we confirmed that the efficiency of the device was significantly enhanced by post annealing process. Its value was increased from 0.18(cd/A) to 1.32(cd/A), approximately 7 times. This phenomenon is a result of improved stability between polymer and metal cathode for injection of electrons as the contact density increases. -
Many well-known pixel compensation circuits have been applied to control TFT
$V_{th}$ variations on small size AMOLED panels. For large (>30-inch) AMOLEDs, luminance and color uniformity are affected by TFT variations, but also by ELVDD IR drop and cavity non-uniformity which are not easily compensated by in-pixel circuits. AMOLED panels may also suffer from manufacturing-induced mura. An external compensation method based on optical measurements is proposed and applied to large AMOLED panels. It improves luminance uniformity by up to 95% at 200nits and color uniformity by up to 99% (${\Delta}$ u'v' <0.004) on large AMOLED panels, and provides-increased margin against processinduced mura. -
The concept of a microplasma current switch for a device operated in a current mode like organic light-emitting diodes, which features matrix addressability and current switching, is presented as well as its architecture and operational principle. To verify the concept, we have fabricated a 100 mm
${\times}$ 100 mm microplasma current switch panel with a cell pitch of$1080{\mu}m{\times}1080{\mu}m$ . Moreover, the current-voltage measurements of the unit cell are performed for three different driving voltage amplitudes. They show the characteristic of an asymmetric floating double probe diagnosing plasmas. -
Lee, Sun-Hee;Kim, Sung-Hoon;Han, Seung-Hoon;Choi, Min-Hee;Jeong, Yong-Bin;Choo, Dong-Joon;Jang, Jin 858
We have applied self-assembled monolayer to make high performance and stable OTFT on the organic gate dielectric. The${\beta}$ -phenethyltrichlorosilane (SAM) was coated on the organic gate dielectric and then active layer was printed. Significant improvements in on-currents and threshold voltage shift were achieved for the SAM treated devices compared to device without SAM. -
Okumura, Mitsuru;Sakamoto, Kunio;Nomura, Shusaku;Hirotomi, Tetsuya;Shiwaku, Kuninori;Hirakawa, Masahito 861
The authors have developed the display system which can be viewed from any direction. In this paper, we propose an omni-directional 3D display system for cooperative activity on a round table. -
Choi, Yong-Gir;Cho, Young-Tae;Park, Seung-Chul;Lee, Yong-Eui;Kim, Chul-Hwan;An, Chee-Hong;Kim, Hyoung-Sub 865
In this paper, we describe the fabrication of nano-scale ink particles with narrow size distribution to offer high optical density in electrophoretic display applications. Charged white ($TiO_2$ and polyester) and black (carbon black and polyester) nano size ink particles in size range of 200 ~ 700nm were made successively using modified non-aqueous base emulsion process. The EPD showed white reflectance of 58% and saturation voltage of${\pm}10V$ . -
Here we report another soft lithography, peel-off method, for patterning conductive polymer anodes in the fabrication of flexible ITO-free organic light-emitting diodes. This method doesn't require any heating process and UV light. We have demonstrated that such a peel-off technique enables the formation of a very sharp edge and the enhancement of edge roughness.
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We report on the growth of rubrene (
$C_{42}H_{28}$ ) wire fabricated by thermal evaporation, followed by solvent-vapor annealing for the application of organic thin film transistor. Solvent-vapor annealing was carried out in precisely controlled vapor pressure at elevated temperature. Micro-sized, and elongated rubrene wire was obtained via solvent annealing process reproducibly. Optical image and XRD data shows highly crystalline quality of rubrene wire. -
This is a report on fabrication and electrical characteristics of pentacene OTFT that uses conducting PEDOT/PSS as source drain electrodes. We demonstrate enhanced conductivity of PEDOT/PSS film with glycerol and optimize properties for ink jet printing. We also present the application of oxygen plasma technique in order to favor selective spreading for subsequent inkjet printing.
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To realize the flexible audible display (FAD), polymer dispersed liquid crystal(PDLC) is deposited on PVDF(Poly-vinylidene fluoride) film with piezoelectric property. With applied audio signal, it makes sound more than 70 dB in 700 Hz-10kHz. In case of transparency it is opaque and transmittance is less than 10% at 550nm wavelength without bias voltage. It is turned to be transparent and show transmittance of 66% with driving voltage of 60V.
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A pixel isolation wall of liquid crystal display is fabricated by the anisotropic photoreaction of a cinnamate based prepolymer. The various oligomers containing a cinnamate moiety were synthesized and used for the formation of the pixel isolation wall. The anisotropic photoreaction of cinnamate moiety was closely related with the liquid crystal orientation at the polymer wall boundary.
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We proposed intriguing and simple technique for fabricating flexible plastic liquid crystal (LC) devices. We made a preliminary version of a flexible LC display employing this concept, and we confirmed this technique was useful for the flexible LC display; the electro-optical reproducibility of the flexible LC device fabricated here was remarkably improved against external perturbation compared with the conventional one.
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We fabricated flexible electronic paper display(EPD) by using toner particles on plastic (PC) substrate. We observed the relationship between contrast ratio and changes of rib structures. One is a fabrication of ribs on bottom substrate. The display with ribs on bottom substrate had higher contrast ratio about 46% than display with ribs on top substrate. The other is a change of density of rib. The less density of ribs fabricated, the higher the contrast ratio become.
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We have developed a practical printing technology for the gate electrode of organic thin film transistors(OTFTs) by combining screen-printing with wet-etching process using nano-silver ink as a conducting material. The screen-printed and wet-etched Ag electrode exhibited a minimum line width of ~5 um, the thickness of ~65 nm, and a resistivity of
${\sim}10^{-6}{\Omega}{\cdot}cm$ , producing good geometrical and electrical characteristics for gate electrode. The OTFTs with the screen-printed and wet-etched Ag electrode produced the saturation mobility of$0.13cm^2$ /Vs and current on/off ratio of$1.79{\times}10^6$ , being comparable to those of OTFT with the thermally evaporated Al gate electrode. -
In this paper, we described the unique and novel method to prepare two kinds of electro-active particles, black and white particles with different polarity. The surface of the particles was characterized to be uniform and clean by adopting spray dryer as a tool for genesis of particles; neither surfactants nor high dielectric medium like water was employed during particle preparation step. The other purpose of this study is to investigate the factors that contribute high driving voltage of particlebased display like QR-LPD. We extracted parameters interaction between particle and electrode, and between oppositely charged particles. Here we reported an excellent behavior of particle-based display that showed low operating voltage, high contrast ratio as high as 8:1 without scarification of quick response time. By optimizing the particle size, charge per mass, selection of external additive sets, a lower driving voltage as low as 40V for the particles with
$10{\mu}m$ volume average diameter was obtained. -
The printed electrodes of organic thin-film transistors (OTFTs) were fabricated by screen printing using nanoparticle silver pastes. The screen printed OTFT corresponds to channel lengths between 7.6 to 82.6
${\mu}m$ (designed L=10 to 80${\mu}m$ ) on the$150{\times}150mm^2$ paper. The channel length deviations for 40 to 80${\mu}m$ patterns were less than 5 %. However, the channel lengths for 10 to 30${\mu}m$ patterns were increased by 20 %. The screen printed bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) OTFTs obtained had a field-effect mobility as large as 0.08 (${\pm}0.02$ )$cm^2$ /Vs, an on/off current ratio of$10^5$ and a subthreshold slope of 1.95 V/decade. -
Lee, Sung-Youp;Kim, Do-Eok;Shin, Byong-Wook;Kang, Byoung-Ho;Hong, Seok-Min;Kang, Shin-Won;Lee, Hyeong-Rag 899
The magnesium fluoride ($MgF_2$ ) has very higher optical transmission than oxide or nitride material applied for gas barrier, so we manufactured Mg-Zn-F films with Mg-Zn-F target mixed in the various ratio of$MgF_2$ to Zn and characterized films' properties. Zn is used to increase packing density of barrier film. Thickness and optical transmission of Mg-Zn-F are 200 nm and over 90 %, respectively. The result of water vapor transmission rate at 38, RH 90 ~ 100% of the Mg-Zn-F film deposited with 4 : 6 ($MgF_2$ : Zn) ratio target reached below$1{\times}10^{-3}g$ /($m^2{\cdot}day$ ), measuring limit of instrument. -
Polymer Dispersed Liquid Crystal (PDLC) films were prepared using the phase separation method with liquid crystal and a newly developed prepolymer. This study investigated the electro-optic characteristics of the PDLC film at various temperatures. It was found that as temperatures increased, the voltage varied, and that the ordinary refractive index of the liquid crystal and the polymer refractive index in the composite had similar dependence at various temperatures.
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Organic field-effect transistor (OFET) memory is an emerging device for its potential to realize light-weight, low cost flexible charge storage media. Here we report on a solution-processed poly[9,9-dioctylfluorenyl-2,7-diyl]-co-(bithiophene)] (F8T2) nano floating-gate memory (NFGM) with top-gate/bottom-contact device configuration. A reversible shift in the threshold voltage (
$V_{Th}$ ) and the reliable memory characteristics were achieved by incorporation of thin Au nanoparticles (NPs) as charge storage sites for negative electrons at the interface between polystyrene and cross-linked poly(4-vinylphenol). -
Low voltage operated top gated polymer transistors were fabricated with a high permittivity polymer, P(VDF-TrFE) and F8T2 as a gate dielectric and semiconducting layer, respectively. The operating voltage of transistors was effectively reduced under -10 V and typical threshold voltages were as low as -1 ~ -4 V with the reasonable charge carrier mobility of
$10^{-3}cm^2$ /Vs for the amorphous polymer. The large hysteresis in transfer curve was improved effectively by annealing at low temperature. -
This paper examines attaching speed, detaching speed and contact time which affected in the ink transfer ratio and presents the best conditions for fabrication process of electrodes with Ag-ink using microcontact printing method. In conclusion, it shows the best printing characteristic by two conditions. One of condition is the attaching speed have to within less than 1mm/s and the detaching speed is high velocity as 1000mm/s and the contact time is taken about the minimum time when inking process. Another condition is the attaching speed have to within more than 100mm/s and the detaching speed have to within less than 1mm/s and the contact time is longer than 30second when the printing process. As using these condition and the stamp sized 5cm
${\times}$ 5cm, it was possible for printing equally until$30{\mu}m$ of width. The printed thickness of a electrode was about 300 to 500 nm, the surface roughness was about dozens nm under 50 nm. -
Using gelatin and acacia as wall and electronic ink as core substance, microcapsules were prepared by complex coacervation to fabricate a flexible electronic paper display. In order to obtain the microcapsules in a narrow dispersed distribution, we focus on the interfacial tension between the hydrophobic electrophoretic ink and an aqueous polyelectrolyte solution, through controlling sodium dodecyl sulphate (SDS) concentration and stirring rate. The existence of anionic surfactant of SDS not only decreases the droplet diameters, but also reduces the diameter size distribution. And, as the stirring rate is increased, the average size of microcapsule is also decreased.
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Effects of nano-silver contents(15~50wt%) on screen printed-etched gate electrodes and electrical characteristics of OTFTs were investigated. As Ag contents increased, the screen-printed film was transferred exactly without spreading and obtained the densely-packed layer with a stable and excellent conductivity but, its thickness was increased and surface became rougher. It was found that the leakage current of MIM devices and off-state currents of OTFTs became larger due to poor step coverage of PVP dielectric layer on the thick and rough gate electrodes for nano-Ag inks with Ag contents more than 30wt%.
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Lee, Yeon-Ju;Lee, Woo-Suk;Jeong, Soo-Kyeong;Choi, Seok-Ju;Kim, Hye-Min;Chun, Jin-Young;Kim, Sung-Ho;Geckeler, Kurt E. 920
Flexible, transparent thin-film transistor with active layers composed of carbon nanotube-based conducting ink were fabricated on a plastic substrate by ink-jet printing. The properties of the formulated conducting ink containing carbon nanotubes, a conducting polymer, and additives were characterized and optimized. The conducting ink was applied to flexible thin-film transistors using ink-jet printing. -
We fabricated large-area OLED lighting device using screen printing. In order to operate full area of large-area OLED uniformly, each cell in OLED panel was designed to work separately. We connected OLED panel with a PCB electrically using jig pins so that each cell could be operated individually. In this presentation, we report a few important issues on the fabrication of large-area OLED for lighting applications.
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Chemical Solution Deposition of InGaZnO Thin Films As Active Channel Layers of Thin-Film TransistorsSon, Dae-Ho;Kim, Jung-Hye;Kim, Dae-Hwan;Sung, Shi-Joon;Jung, Eun-Ae;Kang, Jin-Kyu;Ha, Ki-Ryong 927
We studied the solution processes of IGZO thin films and investigated the electrical characteristics of thin film transistor (TFT) with sol-gel processed InGaZn-oxide active semiconductor layer. In particular, the effect of composition variation and post annealing temperature were studied by using solutions having various metal cation ratios to optimize transistor performance. -
EHA(ethylhexyl acrylate), well known for the prepolymer used for PDLC, was used for the LC/polymer composite system for pixel isolated LC (PILC). In order to improve the polymer wall structures of EHA, various acrylate prepolymers were blended with EHA prepolymer.
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Park, Hyo-Joo;Choi, Hong;Lee, Dong-Hyuck;Kim, Dong-Woo;Bae, Byung-Sung;Kim, We-Yong;Kim, Byung-Uk;Hong, Mun-Pyo 935
In this paper, we describe the basic operating mechanism of our novel reflective display, Fast Moving Ball Actuator (FMBA) mode[1], using micro-sized metal coated polymer ball in fluid medium. Metal surface of the ball can be charged up by contact electrode and their locations can be controlled by applied field to obtain optically on and off state. In the medium with high viscosity, the response speed of the moving ball might be reached into their terminal velocity and changed in proportion to the frequency of applied voltage on the electrodes. -
In this paper, we report electrical properties of OTFTs made by ink-jet printing with polyvinylphenol (PVP) for bank layer and bis(triisopropylsilylenthynyl) pentacene (TIPS-pentacene) for semiconductor. We could achieve better crystallization and surface uniformity of TIPS pentacene by employing PVP bank layer. The OTFT with PVP bank layer exhibited an field-effect mobility of 0.18
$cm^2$ /Vs, current on/off ratio of$2.09{\times}10^5$ , and subthreshold slope of 0.42 V/decane. -
The adsorption strength of liquid crystal molecules on the polymer surface was compared measuring temperature dependence of retardation above Nematic-Isotoropic transition temperature (
$T_{NI}$ ). The relationship between surface order parameter and adsorption strength on the polymer surface was discussed. -
Blue phase shows several different reflection colors from the randomly oriented domains and crystal direction. Also there are variations in the size of domains. The domain size is dependent on the temperature gradient. With smaller cooling rate of temperature, the domain size was increased compared with rapid cooling. With injection of light of specific wavelength, we find that the diffraction patterns were occurred around the light spot in the cell of blue phase. It was supposed to be from the matching of the phase retardation and domain size. However, actually the diffraction pattern is reflecting the lattice structure in double twist of the blue phase. The lattice constant from the radius of diffraction patterns shows very similar one from the reflection spectrum, which indicates the internal lattice constant in double twist of the blues phase.
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We developed a new laser irradiation (BLDA: Blue Multi-Laser-Diode Annealing) system. The system forms the uniform line beam, which is constructed by 48 pieces of semiconductor lasers. This new system has achieved high laser output stability and the highly accurate beam shape by adopting a reliable laser control, the auto-focus control in addition to an original laser photosynthesis technology and the beam homogenizing technology. It was confirmed to crystallize the Si films effectively with good quality.
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A few organosilicon compounds (OC) - both cyclic and linear siloxanes with different structure of the substituents - have been synthesized. Properties of the LC anchoring on OC films have been measured. The OC investigated provide the homogeneous planar alignment with LC tilt angle in the range from
$0.7^{\circ}$ to$1.9^{\circ}$ . An increase of the microrelief depth results in a small increase of the tilt angle. The azimuthal anchoring is better for the films of the OC without molecular microrelief or the OC comprising polar groups. -
The long way toward new silicon technology, processed at very low temperature on any substrate, is described. The technology is based on CMIS (Complementary Metal Insulator Semiconductor) structure that shown its efficiency with known CMOS electronics. Present performance of this new technology is discussed through electrical parameters and reliability of transistors.
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We have investigated the effect of light on amorphous silicon thin film transistors based photo-sensor applications. We have analyzed the instability caused by electrical gate bias stresses under the light illumination and the effect of photo-induced quasi-annealing on the instability. Threshold voltage (
$V_{TH}$ ) under the negative gate bias stress with light illumination was more decreased than that under the negative gate bias stress without light illumination even though$V_{TH}$ caused by the light-induced stress without negative gate bias was shifted positively. These results are because the increase of carrier density in a channel region caused by the light illumination has the enhanced effect on the instability caused by negative gate bias stress. The prolonged light illumination led to the recovery of shifted VTH caused by negative gate bias stress under the light illumination due to the recombination of trapped hole charges. -
Kimura, Mutsumi;Miura, Yuta;Ogura, Takeshi;Hachida, Tomohisa;Nishizaki, Yoshitaka;Yamashita, Takehiko;Shima, Takehiro;Hashimoto, Hayami;Yamaguchi, Yohei;Hirako, Masaaki;Yamaoka, Toshifumi;Tani, Satoshi;Imuro, Yoshiki;Bundo, Kosuke;Sagawa, Yuki;Setsu, Koushi 957
Sensor applications of thin-film transistors (TFTs), such as photosensor, magnetic sensor, temperature sensor and chemical sensor, are introduced. Active-matrix circuits and amplifying circuits using poly-Si TFTs are integrated with these sensors to improve sensor performances and generate additional functions. These sensors may be promising applications after flat-panel displays (FPDs) in giant-micro electronics. -
Lee, Seok-Woo;Lee, Sang-Jin;Ahn, Tae-Joon;Park, Soo-Jeong;Kang, Su-Hyuk;Jung, Sang-Hoon;Lee, Hong-Koo;Kim, Sung-Ki;Park, Yong-In;Kim, Chang-Dong;Yang, Myoung-Su;Kang, In-Byeong;Hwang, Yong-Kee 961
a-Si process-based advanced-SPC (a-SPC) TFT has been developed and verified by manufacturing an AMOLED panel having improved cost competitiveness by using the existing a-Si infrastructure. The a-SPC TFT had superior device reliability and current drivability to a-Si TFT to meet the requirements of AMOLED backplane. -
A new hybrid-type touch screen panel (TSP) has been developed based on a-Si:H TFT which can detect the change of both
$C_{LC}$ and photo-current. This TSP can detect the difference of$C_{LC}$ between touch and no-touch states in unfavorable conditions such as dark ambient light and shadows. The hybrid TSP sensor consists of a detection area which includes one TFT for photo sensing and two TFTs for amplification. Compared to a single internal capacitive TSP or an optical sensing TSP, this new proposed hybrid-type TSP enables larger sensing margin due to embedding of both optical and capacitive sensors. -
Cheng, Hui-Wen;Huang, Hsuan-Ming;Li, Yiming;Tsai, Tseng-Chien;Chen, Hung-Yu;Huang, Kuen-Yu;Hsieh, Tsau-Hua 968
TFT-LCD display system is nowadays one of power-hungry components in portable products; technique of power reduction is thus essential for production of mobile phone. In this work, we minimize the display power, using computationally intelligent statistical methodology. Compared with a conventional design, 68.474% reductions on the current consumption could be obtained for a 2.2-inch of TFT-LCD display system of mobile phone. The total power consumption of the display system consisting of the backlight system and current consumption of display panel is thus successfully reduced form 68.305mW to 64.06mW (about 6.215% reductions). -
This paper presents smart regional contrast enhancement technique of partitioned image for local dimming backlight on small-sized mobile display to reach two goals. One is to save the power consumption, and the other to improve contrast ratio of display image. Recently new advanced method is proposed, named local dimming method, that backlight LED is positioned on backside of the display panel. So it is important to partition an image by sub blocks and then post-processing independantly. This means regional contrast enhancement. After partitioning, we compare the mean luminance(Y) value of each sub-block image with the one of original whole image. If some blocks have the mean value lower than the one of whole image, they are processed with the proposed method and others are bypassed. Simultaneously the information of the processed blocks are transferred to BLC(Backlight LED Controller). And then the supply current of each backlight LED is reduced to realize the contrast ratio enhancement and at the same time to power consumption reduction. In addition, we verify this proposed method is free from blocking artifacts.
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Even if auto-stereoscopic and polarization based 3D displays are not working with the same principles, their common aim is to provide two different images in the eyes of the observer. In this paper we show that Fourier optics instrument for viewing angle measurements can be applied to both types of displays. Luminance measurements are made at different locations and what will be seen by an observer in front of the display is predicted. Precise 3D characteristics can be derived and direct comparison becomes possible.
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Lee, Eun-Jung;Chong, Jong-Ho;Yang, Sun-A;Lee, Hun-Jung;Shin, Mi-Ok;Kim, Su-Young;Choi, Dong-Wook;Lee, Seung-Bae;Lee, Han-Yong;Berkeley, Brian H. 979
With increasing demand for better FPD image quality, better evaluation metrics and advanced display quality measurement methods are required to meet these needs. There are many measurement methods to evaluate viewing angle of the various different display devices. However, these methods, which include luminance drop, color shift, and contrast ratio decrease, are imperfect considering that human perception does not completely correlate to these methods. In this paper, we propose a new method for measuring perceptual angle of FPDs considering human visual perception, which uses color space of the color appearance model. -
Motion-induced artifacts on LCDs appear as blurred boundaries and/or color aberration between the moving objects and background. Perceived degree of the motion-induced artifacts depends on the blur width as well as color difference. This paper presents a quantitative measure for the motion-induced artifacts on LCDs. Performance of the proposed measure is verified by calculating correlation coefficients between the proposed measures and the results of human visual tests performed on the 240 Hz and 120 Hz scanning LCD TVs.
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This paper reports of camera detection of Mura. The type, location, size, orientation and amplitude are found. As the luminance variation in Mura is down to less than app. 0.3 %, measurement apparatus, techniques and algorithms are developed to measure low noise data and to extract the Mura from data with the residual noise in the same magnitude as the Mura.
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$In_2O_3$ thin-film transistors (TFTs) were fabricated on various dielectrics [$SiO_2$ and self-assembled nanodielectrics (SANDs)] by spin-coating a$In_2O_3$ film precursor solution consisting of methoxyethanol (solvent), ethanolamine (EAA, base), and$InCl_3$ as the$In^{3+}$ source. Importantly, an optimized film microstructure characterized by the high-mobility$In_2O_3$ 004 phase, is obtained only within a well-defined base:$In^{3+}$ molar ratio. The greatest electron mobilities of ~ 44$cm^2$ , for EAA:$In^{3+}$ molar ratio = 10,$V^{-1}s^{-1}$ , is measured for$n^+$ -Si/SAND/$In_2O_3$ /Au devices. This result combined with the high$I_{on}:I_{off}$ ratios of ~$10^6$ and very low operating voltages (< 5 V) is encouraging for high-speed applications. -
Kim, Tae-Woong;Stryakhilev, Denis;Jin, Dong-Un;Lee, Jae-Seob;An, Sung-Guk;Kim, Hyung-Sik;Kim, Young-Gu;Pyo, Young-Shin;Seo, Sang-Joon;Kang, Kin-Yeng;Chung, Ho-Kyoon;Berkeley, Brain;Kim, Sang-Soo 998
A new flexible TFT backplane structure with improved mechanical reliability is proposed. Amorphous indium-gallium-zinc-oxide (a-IGZO) thin film transistors based on this structure have been fabricated on a polyimide substrate, and the resultant mechanical durability has been evaluated in a cyclic bending test. The panel can withstand 10,000 bending cycles at a bending radius of 5 mm without any noticeable TFT degradation. After 10K bending cycles, the change of threshold voltage, mobility, sub-threshold slope, and gate leakage current were only -0.22V, -0.13$cm^2$ /V-s, -0.05V/decade, and$-3.05{\times}10^{-13}A$ , respectively. -
Solution-processed indium-gallium-zinc-oxide thin-film transistors were fabricated by sol-gel method. By a combinatorial study of InGaZnO multi-component system, optimum molar ratio of In, Ga, and Zn has been selected. By adjusting the In:Ga:Zn molar ratio, TFTs with field-effect mobility of 0.5 ~ 1.5
$cm^2$ /V-s, threshold voltage of -5 ~ 5 V, and subthreshold slope of 1.5 ~ 2.5 V/decade were achieved. -
Matsumoto, Yuuki;Sakamoto, Kunio;Nomura, Shusaku;Hirotomi, Tetsuya;Shiwaku, Kuninori;Hirakawa, Masahito 1005
An invisible code is one of the useful technologies for a computer interaction. In this paper, we propose a method to display invisible codes using LCD panels and to detect a polarized symbol image with a conventional CCD camera. -
Stereoscopic 3D technology using patterned retarder and eyeglass of circular polarizer shows dependence on the user position and condition of circular polarizer eyeglass. Cause of these dependencies and its effects on the 3D display performances were analyzed.
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The analytical expression for quality function is found including the dependence on disparity. The problem is considered in the projective coordinates for which the forward and backward transformation matrices are found. The formation of side observer regions is considered. The probability of the pseudo stereo effect is also estimated. Testing patterns are improved in order to provide higher accuracy of measurements. This is confirmed in experiments.
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Define a designated eye position (DEP) for the 3D displays is a critical issue. It shows the system performance without content issue. We use luminance meter to capture these optical characteristic and discuss between one point measurement, two points measurement and three points measurement situation.
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Stereoscopic Images provide depth information with the relative distances between the objects in the images. There are many different ways to extract disparity maps from the visible spectral images. For the infrared spectral range, the same approach cannot be utilized for the innate low resolution and colorless features because typical methods require corresponding features between the images. The authors suggest a new approach that makes use of image segmentation to obtain depth information for stereoscopic millimeter-wave images. For image segmentation a selective visual attention model based on the theory of a feature-integration of attention is used. Experimental results show the proposed method provides reasonable depth information for object shape recognition and display.
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Jang, Jin-Nyoung;Song, Byoung-Chul;Oh, Kyoung-Suk;Yoo, Suk-Jae;Lee, Bon-Ju;Choi, Soung-Woong;Park, Young-Chun;Hong, Mun-Pyo 1025
Novel low temperature deposition process for nano-crystalline Si thin film is developed with the hyper-thermal neutral beam (HNB) technology. By our HNB assisted CVD system, the reactive particles can induce crystalline phase in Si thin films and effectively combine with heating effect on substrate. At low deposition temperature under$80^{\circ}C$ , the HNB with proper incident energy controlled by the reflector bias can effectively enhance the nano-crystalline formation in Si thin film without any additional process. The electrical properties of Si thin films can be varied from a-Si to nc-Si according to change of HNB energy and substrate temperature. Characterization of these thin films with conductivity reveal that crystalline of Si thin film can increase by assist of HNB with appropriate energy during low temperature deposition. And low temperature prcoessed nc-Si TFT performance has on-off ratio as order 5. -
High quality poly-SiGe thin films were prepared on 6-inch substrates using Reactive-thermal CVD with
$Si_2H_6$ and$GeF_4$ around at$500^{\circ}C$ directly. Its thickness uniformity was ~ 3% on the entire substrate area. N-channel mobility of ~30 nm thick bottom-gate TFTs exceeded 20$cm^2$ /Vs without any further crystallization. -
Several different production technologies for Low-Temperature Poly-Silicon (LTPS) have been proposed over the last years. However, finally the progress in Excimer-laser-based crystallization has lead to the best cost-to-performance ratio of LTPS manufacturing for use in active-matrix-based displays. In this paper, we report on recent and significant technical advances in light sources, optical beam deliveries and beam irradiation systems targeted at enabling ultra-uniform mura-free LTPS active-matrix backplanes while simultaneously lowering production costs and increasing throughput.
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We have developed an automated circuit defect repair method. We focused on the resist patterns on the circuit material layer of TFT substrates before the etching process. In this paper, we report on the repair method that utilizes the syringe system and the stability of the open defect repair process.
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Jeong, Byoung-Seong;Park, Chang-Mo;Kim, Mu-Gyeom;Chung, Hyun-Joong;Ahn, Tae-Kyung;Heo, Seong-Kweon;Jeong, Jong-Han;Kim, Min-Kyu;Park, Hye-Hyang;Huh, Jong-Moo;Mo, Yeon-Gon;Kim, Hye-Dong;Kim, Sang-Soo 1040
a-IGZO is an attractive material to make an AMOLED device with uniform TFT properties for use in a large size display. However, this material shows TFT properties that are very sensitive to water or hydrogen. Therefore, it is essential to control these critical factors during fabrication of the backplane in order to improve the TFT performance. In this paper, we report the effect of passivation layer properties on the performance of the oxide TFTs. -
Here we report the architecture for a non-volatile n-type memory paper field-effect transistor. The device is built using the hybrid integration of natural cellulose fibers (pine and eucalyptus fibers embedded in an ionic resin), which act simultaneously as substrate and gate dielectric, with amorphous GIZO and IZO oxides as gate and channel layers, respectively. This is complemented by the use of continuous patterned metal layers as source/drain electrodes.
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The two approaches to improve the stability of oxide TFTs are described. First approach is the optimization of device architecture including MIS structure and passivation layer using conventional InGaZnO semiconductor channel layer. Second approach is to develop the new kinds of oxide semiconductor materials, which is very robust and stable against the gate bias stress and thermal stress.
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Li, Flora M.;Hsieh, Gen-Wen;Nathan, Arokia;Beecher, Paul;Wu, Yiliang;Ong, Beng S.;Milne, William I. 1051
This paper investigates approaches for improving effective mobility of organic thin film transistors (OTFTs). We consider gate dielectric optimization, whereby we demonstrated >2x increase in mobility by using a silicon-rich silicon nitride ($SiN_x$ ) gate dielectric for polythiophene-based (PQT) OTFTs. We also engineer the dielectric-semiconductor ($SiN_x$ -PQT) interface to attain a 27x increase in mobility (up to 0.22$cm^2$ /V-s) using an optimized combination of oxygen plasma and OTS SAM treatments. Augmentative material systems by combining 1-D nanomaterials (e.g., carbon nanotubes, zinc oxide nanowires) in an organic matrix for nanocomposite OTFTs provided a further boost in device performance. -
The mobility of charge carriers has been investigated in the pristine and phosphorescent materials doped host materials using time-of-flight photoconductivity technique. The field and temperature dependences of the mobility were analyzed with the Gaussian disorder model. Based on these results, we optimized white organic light emitting diodes (WOLEDs) consisting of multi-emitting layers doped with phosphorescent and fluorescent dopants. Especially, we studied the effect of each emitter position and an interlayer on the device characteristics of WOLEDs.
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We have investigated the pristine alkali metal doping effect which is the Fermi level of alkali metal doped Alq3 shifts toward the LUMO. In-situ measurements of synchrotron radiation photoelectron spectroscopy revealed that the interface dipole or bend bending in previous reports are not the pristine alkali metal doping effect
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Through dark injection space-charge-limited current (DI-SCLC) and trap-free SCLC measurements, it has been demonstrated that an indium tin oxide (ITO)/buckminsterfullerene (
$C_{60}$ ) electrode can form a quasi-Ohmic contact with N, N'-bis (naphthalen-1-yl)-N, N'-bis(phenyl) benzidine (NPB). The DI-SCLC results show a clear peak current along with a shift of the peak position as the field intensity varies, implying an Ohmic (or quasi-Ohmic) contact. A theoretical simulation of the SCLC also shows that ITO/$C_{60}$ forms an Ohmic contact with NPB. The Ohmic contact makes it possible to estimate the NPB hole mobility through the use of both DI-SCLC and trap-free SCLC analysis. This also contributes to a reduction in power consumption. -
The current study introduces a new color space applicable to next-generation media such as UHDTV and 3D-TV systems that are in the middle of development. Display referred approach was taken into account rather than scene referred approach for deriving a new RGB-primary set forming the new color space. The reproducible color range generated by the newly suggested RGB-primary set encompasses almost entire real-world surface colors with a very good efficiency.
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Field sequential display has some advantages but color breakup (CBU) is the significant problem. Many researches had introduced several methods to reduce CBU phenomenon, however there are no reliable methods to measure the degree of CBU. In this report, a novel CBU measurement technique which was based on the image processing method and subjective analysis results had proposed to evaluate the degree of CBU. Color Breakup Index (CBI) was presented to be a useful index to recognize the CBU phenomenon in the different field sequential technique displays.
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The dependences of color gamut size and power consumption on the area ratio of neutral and green sub-pixels for the RGBW LCD with RGB LED backlit are studied, in which the areas of red and blue sub-pixels are the same and are one quarter of pixel apertu re area. It is found that high color saturation and power saving can be achieved for the proposed RGBW LCD.
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Lee, Hun-Jung;Choi, Dong-Wook;Lee, Eun-Jung;Kim, Su-Young;Shin, Mi-Ok;Yang, Sun-A;Lee, Seung-Bae;Lee, Han-Yong;Berkeley, Brian H. 1077
In this paper, we propose a new method for measuring image sticking of an OLED display using a human visual test. We determined that the perceptual image sticking threshold is 2% of luminance difference at 200 nits and 1% at 100 nits, respectively. Color shift must also be considered when evaluating image sticking, as a${\Delta}$ (u', v') shift of just over 0.002 can be recognized regardless of background brightness. Perception of image sticking is affected by the background level, test pattern, and ambient illumination conditions. The evaluation standard must consider both luminance variation and color shift simultaneously. -
We have already developed EMI reducing techniques using lossless compression by vertically differential EMI suppression method (VDE[1]). It applies lossless modulo reduction and data bit mapping optimization for low voltage differential signaling (LVDS) transmission lines, that reduces the probability of transient bit and EMI by 12 dB [6][7]. We also improved and optimized the VDE for low power LCD interface. With this modified VDE algorithm[8], the developed FPGA was measured the reduction of the power consumption of LCD circuit by more than 15 % compared to the conventional methods in the case of 14-in LCD with SXGA resolution. The VDE algorithm is based on the total image systematic approach. In the VDE method, the present image signals are subtracted for the 1H delayed image signals and transferred to a column driver through a PCB. As the vertical correlations for image signals are very high, we expected that most of the vertically subtracted image signals remain 0 level and transient cycles become very long. As a result, the power consumption and EMI are extremely reduced for the transferred image signals on a PCB. In this paper, we discussed our proposed method by emphasizing the fact that systematic approach are important based on not only display point of view but also total system point of view.
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A small temperature sensor is designed in a 0.35um CMOS process. Transistors operating in the intermediate inversion region are employed in the core of the sensor. This temperature sensor operates in
$-50^{\circ}C{\sim}120^{\circ}C$ with${\pm}2^{\circ}C$ of accuracy after two-point calibration. This temperature sensor can be placed in the active pixel area of a display panel to measure the temperature of the display panel for temperature compensation. -
A boost converter with charge-recycling technique fabricated by
$0.25{\mu}m$ CMOS BCD process can provide different supply voltages to drive series RGB LEDs in sequence for reducing the power consumption on the constant current generator. The proposed technique stores and restores extra energy to improve the efficiency, as well as enhances the reference tracking response. Experimental results show that the period of reference-tracking response can be improved. When the load current is 100mA, the periods of reference down-tracking and uptracking are smaller than$10{\mu}s$ and$20{\mu}s$ , respectively. Experimental results demonstrate fast and efficient reference tracking performance is achieved. -
The purpose of the research was to figure out the optimal binocular parallax inducing the least 3D visual fatigue. Subjective 3D visual fatigue was measured while the revolution depth and the average depth of an object were manipulated. The optimal binocular parallax was figured out by using data fitting method.
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Stereoscopic (3D) content must be viewable in a variety of visual environments, from 3D theaters to 3D mobile displays. However, the depth sensations provided by 3D media are affected by the viewing conditions, such as screen size, viewing distance, and other factors. This user experience (UX) aspect makes it difficult to create multi-purpose 3D content. This paper describes two study cases in which the authors have focused on the UX and the multi-purposing of 3D content. The first case is an evaluation of 3D image quality on a mobile display. The second case is a trial development of a scalable 3D conversion process.
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Conventional stereoscopic (3D) displays using binocular parallax generate unnatural conflicts between convergence and accommodation. Those conflicts can affect the ability to fuse binocular images and may cause visual fatigue. This study examined time-series changes in visual fatigue and depth sensation while viewing stereoscopic images with changing parallax. We examined the physiological changes, including the subjective symptoms of visual fatigue, when viewing five parallax conditions. The time-series results suggest that 2D and 3D images produce significantly different types of visual fatigue over the range of binocular disparity.
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In this paper, we investigated the properties of hypostereoscopic condition in mobile circumstance and simulated the main factors to embody an effective presence to the reconstructed depth image, which are both the limited disparity for fusible stereo and the object space possible for quantifying.
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Flat panel multiview 3D displays developed in recent years have pseudoscopic regions that appear unnatural to viewers. We suggest a new method to suppress the pseudoscopic regions based on the visual characteristics of binocular rivalry. We confirm the validity of this method experimentally and show that the unnaturalness caused by pseudoscopic regions can be effectively suppressed.
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Liu, Kang-Hung;Wang, Hsing-Lung;Ku, Chun-Kang;Chen, Ru-De;Lin, Yan-Rung;Chang, Chih-Yuan;Lin, Chun-Yuan;Lee, Mei-Ju;Kuo, Chia-Wei;Ciou, Jyun-Kai;Liao, Chi-Chang 1112
In this paper, we have studied manufacturing process for liquid crystal displays (LCDs) using plastic substrates. Because the thermal and dimensional stabilities of plastic substrates are decisive issues, both the process and materials were improved to fit the manufacturing requirements of flexible twisted-nematic (TN) and color super-twisted nematic (CSTN) LCDs. Finally, to broaden the flexible display applications, we take advantage of the unique properties of flexible display to design several innovative products. -
Chang, Jae-Hyuk;Lee, Seung-Jun;Park, Dae-Jin;Bae, Joo-Han;Lee, Sung-Hee;Kim, Jang-Kyum;Kim, Kyu-Young;Bae, Jung-Mok;Kim, Bo-Sung;Lim, Soon-Kwon 1115
Resist patterning of all layers in TFT and BM layer in CF were carried out using UV-imprinting Lithography to make a 12.1 inch TFT-LCD panel at the resolution of 1280${\times}$ 800 lines (125 ppi). Technical challenges and solutions for resist patterning by UV-imprinting are shown in this article. -
Shin, Hong-Sik;Baek, Kyu-Ha;Yun, Ho-Jin;Ham, Yong-Hyun;Park, Kun-Sik;Lee, Ga-Won;Lee, Hi-Deok;Wang, Jin-Suk;Lee, Ki-Jun;Do, Lee-Mi 1118
We have fabricated inverted staggered pentacene Thin Film Transistor (TFT) with 1-${\mu}m$ channel length by micro contact printing (${\mu}$ -CP) method. Patterning of micro-scale source/drain electrodes without etching was successfully achieved using silver nano particle ink, Polydimethylsiloxane (PDMS) stamp and FC-150 flip chip aligner-bonder. Sheet resistance of the printed Ag nano particle films were effectively reduced by two step annealing at$180^{\circ}C$ . -
Organic thin-film transistors (OTFTs) were fabricated by using the transfer patterning method. In order to remove Au pattern easily, UV-curable polymer mold was surface treated. Au source/drain (S/D) pattern was transferred to insulator-coated substrate surface. Fabricated OTFTs were compared to OTFTs using vacuum-deposited Au S/D. Additionally, transistor diodes were characterized.
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Conversion of light energy to electrical energy by using a solar cell has long been considered as one of the option for an electrical energy supply in the future. In the past, commercial use was restricted largely to remote area applications where conventional electricity is expensive. Recently, the major application of the solar cells changed to become generation of residential electricity in urban areas where the electricity is already supplied by the conventional grid. This paper covers the current market and technology status of the solar cells and future prospect of their terrestrial applications. Reviewing market trend, this paper discusses high efficiency approach in silicon solar cells, low cost approach in silicon solar cells and finally covers future prospects of silicon solar cells.
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Here the improved performance of polymer/polymer solar cells, which are of importance to achieve real plastic solar cells in the near future, is reported. First, the progress in polymer/polymer solar cells is briefly reviewed and then the limiting factors are discussed in terms of charge transport.
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We propose a novel way for enhancement of efficiency on a quasi solid-state dye-sensitized solar cell (DSSC). It contained gel type electrolyte mixing the liquid crystal (LC) of specific concentration and applied voltage for alignment of the LC. Aligned LC is supported charge transfer inside electrolyte and efficiency is increased in DSSC. We made a quasi solid-state DSSC which applied DC voltage or not and have measured the power conversion efficiency (PCE) and the fill factor. From measurement, we obtain high performances in case of cell applied voltage compare to reference cell.
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The rolls of triplet excitons in a polymer based photovoltaic (PV) device are investigated for improving the efficiency of PV devices. Generally, the thick photo-absorbing layer can improve the PV device efficiency by increasing the photon absorption. However, in case of PV devices with singlet excitons, the efficiency is limited by the short exciton diffusion length, which depends on the mobility and lifetimes of excitons. Therefore, using the triplet excitons, which have a higher mobility and longer lifetime, can solve the problem of premature exciton dissociation caused by the shorter singlet exciton diffusion length in the thick photo-absorbing layer. In this study, the triplet exciton dynamics of a conjugated polymer in a phosphorescent dye blended polymer PV device is investigated by photo-induced absorption, and PV devices performance at various concentrations of phosphorescent dye are is also evaluated.
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Recently, various Ni doping systems and thermal annealing systems have been developed for fabrication of polycrystalline silicon film using SGS (super grain silicon) for medium and largesize AMOLED panels. In this study, we compare the potential of Ni doping systems including ALD (atomic layer deposition), AMD (atmospheric metal deposition), in-line sputter, and crystallization annealing systems including batch type furnace, inline furnace, and RTA (rapid thermal annealing) developed for the SGS method. Additional requirements for those systems to be used for mass production of large AMOLED TVs are suggested based on evaluation results for both poly-Si films and TFT backplanes.
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Schwambera, Markus;Keiper, Dietmar;Meyer, Nico;Heuken, Michael;Lindla, Florian;Bosing, Manuel;Zimmermann, Christoph;Jessen, Frank;Kalisch, Holger;Jansen, Rolf H.;Gemmern, Philipp Van;Bertram, Dietrich 1140
Organic Vapor Phase Deposition (OVPD) equipment enables the accurate and simultaneous control of deposition rates of multiple materials as well as their homogenous mixing in the gas phase. Graded or even cross-faded layers by varying carrier gas flow are options to improve OLED performances. As example, we will show how the efficacies of standard red phosphorescent OLEDs with sharp interfaces can be increased from 18.8 cd/A and 14.1 lm/W (1,000 cd/$m^2$ ) to 36.5 cd/A (+94 %, 18 % EQE) and 33.7 lm/W (+139 %) by the introduction of cross-fading, which is a controlled composition variation in the organic film. -
SAES has developed a range of dispensable dryer solutions, based on different technologies and materials. Among these, DryPaste, a thermally curable and screen printable solution, AqvaDry, a transparent solution which maintains its transparency even after water sorption, and ZeoGlue, an edge sealant with active barrier properties
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Juang, Fuh-Shyang;Tsai, Yu-Sheng;Wang, Shun-Hsi;Chen, Chuan-Hung;Cheng, Chien-Lung;Liao, Teh-Chao;Chen, Guan-Wen 1148
A self-designed, written in labview, Organic Light-Emitting Diode junction temperature measuring program was used to calculate the internal junction temperature for devices during operation, and an infrared thermometer was used to measure the backside temperature of the device substrate, to discuss the effects of the junction and substrate temperature difference to the characteristics of the device. -
Although motion impression is weak with isoluminant color stimuli, it has been shown that color signals influence motion perception. We discuss similarities and differences between color motion and luminance motion, focusing on temporal characteristics of the perception of the 2D and 3D motion.
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This template provides you with an example of the The CIE Color Appearance Model (CIECAM02) is now widely used for various digital imaging systems including digital displays. The CIECAM02 were intended to be an empirical model, however, some aspects of the model are closely related to the human color vision mechanism. This paper will discuss the relationship between human color vision and color imaging.
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Tri-stimulus values of CIE-XYZ and RGB values obtained by photographic film, CCD camera or scanner depend on the spectral sensitivity of imaging devices and the spectral radiant distribution of the illumination. It is important to record and reproduce the reflectance spectra of the object for true device independent color reproduction and high accurate recording of the scene. In this paper, a method to record the reflection spectra of the object is introduced and its application to spectral endoscopes is presented.
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Many researches showed that perceived image contrast increases as the relative surround luminance increases. However, most experiments were conducted under limited surround conditions. In this research, a psychophysical experiment was conducted to investigate the change in perceived image contrast under wide range of surround luminance up to 1820 cd/
$m^2$ . A large area illuminator was used as a backlight. It consists of 23 dimmable fluorescent lamps and a sheet of diffuser. The luminance could be adjusted to 7 different surround ratios: 0, 0.3, 0.56, 0.96, 2.24, 5.81, and 9.99. Results showed that perceived image contrast changes as a typical band-pass shape and the maximum contrast is found near$S_R$ =1. -
Motion-image-quality of LCD-TVs is discussed by dynamic spatial frequency response. Smaller temporal aperture or higher frame rate can improve dynamic response, but an increase of motion velocity easily cancels the improvement. A guideline for deciding the desirable temporal aperture and frame rate of LCD-TVs is described, under the condition that camera and display have the same parameters. Two candidates of the desirable parameter sets will be (240 or 300 Hz, 50 to 100% aperture) and (120Hz, 25 to 50% aperture), from the viewpoint of "limit of acceptance" on motion-imagequality-deterioration for critical picture materials.
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We propose a low cost, high performance, effective overdrive implementation method for liquid crystal display systems. The technique can calculate all overdrive values using higher order approximation algorithm by only three measurements. We find that our technique can be applied regardless of LCD panels. Due to its simplicity, we can also tune motion performance of the LCD systems without measurements.
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Color sequential display is a well know technology. Hower, due to the slow response time of LC,the CSD has not been used in LCD. We have developed a unique LC color display, which can improve LC response time, improve the driving system, improve the gamma drive issue and increase the color gamut to more than NTSC120%.It also can get very low power consumption merit.
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Recently, researches on holographic 3D video display are getting very active, though the goal is still challenging. This paper describes recent research activities on the holographic video system in Japan. It includes hologram calculations and acquisitions as well as displays.
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Leister, Norbert;Futterer, Gerald;Haussler, Ralf;Reichelt, Stephan;Sahm, Hagen;Schwerdtner, Alexander;Schwerdtner, Armin;Stolle, Hagen 1179
In 2007 SeeReal had demonstrated the first large realtime holographic 3D display based on tracked viewing windows. Subsequent work has lead to advanced concepts for overcoming limitations of the prototype. This paper describes the current state of SeeReal's developments and its progress in practical realization of these advanced solutions. -
We have developed several three-dimensional display systems matched to human visual field characteristics. In this article, we describe these systems corresponding to a close-range, mid-distance and distance view, and also the image pickup equipments related to these display systems.
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In this paper we interface Tangible Devices (i.e. Haptic Devices) for 3D Virtual World based on MPEG-RoSE syntax. We called it Virtual World and Real World Interface (VRI). The VRI Technology project intends to provide virtual world information to real world and tangible experience to user of virtual world through tangible devices.
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Yang, J.Y.;Hong, G.S.;Kim, K.;Bang, J.H.;Ryu, W.S.;Kim, J.O.;Kang, Y.K.;Yang, M.S.;Kang, I.B.;Chung, I.J. 1189
Short channel a-Si:H TFT devices with Cu electrodes have been investigated. Short channel TFTs are defined by new plasma etch process. When the channel length becomes shorter, the TFT characteristics (threshold voltage, off current, sub threshold voltage, etc.,) are degraded. These degraded characteristics can be improved through the hydrogen plasma treatment and new gate insulator structure. Using these processes, 15.0 inch XGA LCD panel was fabricated successfully where the channel length of the TFT devices was about 2.5 micrometers. -
Kugimiya, Toshihiro;Goto, Hiroshi;Hino, Aya;Nakai, Junichi;Yoneda, Yoichiro;Kusumoto, Eisuke 1193
Low resistivity interconnection and high-mobility channel are required to realize ultrahigh-definition LCDs such as 4k${\times}$ 2k TVs. We evaluated fully Cu-based gate and Source/Drain interconnections, consisting of stacked pure-Cu/Cu-Mn layers for TFT-LCDs, and found the underlying Cu-Mn alloy film has superior adhesion to glass substrates and CVD-SiOx films. It was also confirmed that wet etching of the Cu/Cu-Mn films without residues and low contact resistance with both channel IGZO and pixel ITO films can be obtained. It is thus considered that the stacked Cu/Cu-Mn structure is one of candidates to replacing conventionally pure-Cu/refractory metal. -
Self-alignment for the fabrication of printed thin film transistors has become of great interest because of the resolution and registration limits of printing technologies. In this work, self-patterning and selfregistration processes are introduced, which do not need surface energy patterning and the resulting minimum gate channel length could be down to
$11.2{\mu}m$ with the sheet resistance of 2.6${\Omega}/{\square]$ for the source and drain electrodes. -
Chung, Won-Suk;Lee, Hyun-Jung;Lee, Won-Mok;Ko, Min-Jae;Park, Nam-Gyu;Ju, Byeong-Kwon;Kim, Kyung-Kon 1200
A solution processed polymer tandem cell has been fabricated by using the organic layer coated crystalline$TiO_2$ nanoparticle inter layer. The highly dispersive OL-$TiO_2$ has several advantages in terms of excellent film forming property, crystallinity, optical transparency, and well defined chemical composition. The surface morphology of the$TiO_2$ thin film was found to play a crucial role in the performance of the polymer tandem cell. The stability of the tandem cell, utilizing dense$TiO_2$ nanoparticles inter layer, was superior to the stability of the single junction cell. -
We investigated the device performance of bulk heterojunction solar cells depending on the active layer thickness. For the systematic comparison, the polymer solar cells comprising RR-P3HT:PCBM (1:0.8 (wt%:wt%)) blend films with different thickness were characterized by impedance spectroscopy, and J-V measurement in dark and solar simulated illumination. The device with 120 nm thickness of active layer exhibited maximum power conversion efficiency of 3.5 % under AM 1.5 100mW/
$cm^2$ illumination condition. -
This study compares and contrasts the market size, growth rates, business cycles, supply and demand of the of the FPD and Photovoltaic (PV) industries. Using historic, market metric, cycle, capacity and other comparative analysis techniques, implications for implementing effective business strategies are formed.
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The theoretical equations for J-V characteristics in an OLED was derived according to the internal carrier emission equation based on a diffusion model at Schottky barrier contact and the mobility equation based on the Pool-Frenkel model. The J-V characteristics of OLED are presented using a behavioral model for analog systems (Verilog-A language), and the accuracy of this model was verified by comparing with the device simulation results.
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Recently,electroluminescence devices based on organic semiconductors have made considerable progress. Displays based on organic light emitting diodes (OLED) are commercially available. To gain broader acceptance, the performance of OLED devices has to be further improved, in particular for lighting. This article discusses the possibility to use controlled electrical doping for improving the properties of devices and new approaches for highly efficient white OLED.
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The effect of silver (Ag) nano-particles on OLEDs was investigated by using a finite difference time domain (FDTD) tool. The proposed OLEDs employed Ag nanoparticles thermally deposited in a high vacuum on a cathode. The emission rate of the exciton was improved by 1.8 fold compared to the conventional OLEDs without Ag nano-particles. Less spacing between the dipole source and the Ag nano-particles resulted in a larger emission rate of the exciton in the OLED with nano-particles. The size of the Ag nano-particles was proportional to the emission rate of the exciton in a range of nano-meter scale of nano-particles. The enhancement of the emission rate of the exciton due to Ag nano-particles caused the improvement in the efficiency of the proposed OLED.
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When evaluating the quality of images and displays, it is important to combine the characteristics as perceived by the human visual system and measured by equipment using subjective and objective methods, respectively. In the case of objective methods, the quality of a display is measured using colorimetric or radiometric devices according to existing standards covering the color temperature, gamut size, gamma characteristic, and device characterization. Meanwhile, subjective methods assess the quality of an image using the human visual system based on a comparison with a reference or counterpart using such metrics as the sharpness, noise, contrast, saturation, and color accuracy. Objective and subjective methods are usually used together in comparison, as ultimately it is observers watching images on a display. In addition to existing objective methods, a new image quality metric is also introduced as regards the JPEG compression ratio that is reflected in the relationship between the gamut size and the color fidelity in CIELAB color space.
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This paper presented an automatic system for display quality measurement by image processing. The goal is to replace human eyes for display quality evaluation by computer vision and get the objective quality review for consumer to make purchase of monitor or TV. Color, contrast, brightness, sharpness and motion blur are the main five factors to affect display quality that could be measured by supplying patterns and analyzing the corresponding images captured from webcam. The scores are calculated by image processing techniques. Linear regression model is then adopted to find the relation between human score and the measured display performance.
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Image compression techniques such as JPEG and MPEG induce losses of image quality. These losses are usually investigated on the spatial distortions from reconstructed images. Representative specifications are blocking artifacts, color bleeding and smearing. However, the compression techniques also influence the color information. The distortion of color information means distortion of gamut characteristics such as gamut size and unique color from the CIELAB values for each pixel in the reconstructed images. Accordingly, this paper introduces the investigation of the relationship between image compression and the gamut characteristics for reconstructed images using MPEG compression. The results show the consist variation of gamut, hue, and chroma due to MPEG compression.
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Each LCD TFT panel requires a power supply IC on the panel board. The IC provides the power rails for the timing controller, source and gated driver IC and others. The industry trend moves towards higher integrated devices. The challenge for the panel manufacturer is the development and implementation of such an IC in cooperation with the semiconductor supplier. If not done carefully the solution will not reduce the overall solution cost or can't provide the expected performance and reliability. This paper discusses the key considerations to successfully develop and integrate a highly integrated LCD bias IC into the system.
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This paper describes a new 160x80 passive-matrix OLED driver ASIC capable in applying multi-line addressing (MLA). Application is directed towards highly-reliable displays, e.g. in automobiles.
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A novel a-Si TFT integrated gate driver circuit which suppresses the threshold voltage shift due to prolonged positive gate bias to pull-down TFTs, is reported. Negative gate-to-drain bias is applied alternately to the pull-down TFTs to recover the threshold voltage shift. Consequently, the stability of the circuit has been improved considerably.
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Lee, Do-Young;Ji, Ju-Hyun;Koo, Hoe-Woo;Yoo, Ki-Taek;Cho, Suk-Ho;Song, Jae-Hun;Yoo, Sung-Rok;Kim, Jae-Sang;Park, Cheol-Woo;Park, Jae-Hong;Lee, Kyung-Ho 1247
We have successfully developed the 22 inch WSXGA+ DLS(Data Line Sharing) Panel driving in 75 Hz. In the large size and high resolution panels, it is very difficult to design the DLS Panels without failure because of the very short charging time and the large signal delay. So, we first investigated the charging order to find the most adequate charging type to the large size and high resolution panels. And then, we optimized the design of DLS in terms of improving the charging properties using the technologies of the Delta-doping TFTs, Cu metal electrodes and optimization of panel design value and the circuit signal timing. -
Integral imaging provides an efficient way to display three-dimensional images with high degree of viewing freedom. Pickup process of integral imaging can also be utilized to acquire three-dimensional contents for displays. This paper introduces basic principle and recent progress of integral imaging technique.
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A 360-degree viewable three-dimensional display based on integral imaging is proposed. The cylindrically arranged point light source array which is generated by electroluminescent (EL) pinhole film reconstructs 360-degree viewable virtual 3D image at the center of the cylinder. In this paper, the principle of operation and experimental results are presented.
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Generally, if we want to change the perspectivity of objects, we should change the position of object or camera, forward or backward. In this paper, recognition of the perspectivity of objects is proposed by using a new elemental image array which is made change the pinhole points horizontally.
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The use of imaging colorimeter systems and associated analytical software to assess display brightness and color uniformity, contrast, and to identify defects is well established. In this paper we describe recent work to extend these methods to classify defects based on human visual perception.
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In this paper, the effect of a flow barrier and bypass on the cooling performance for a straight fin heat sink is presented. Both side directions and upward direction of bypass are controlled using various ducts which have different width and heights. In addition, a flow barrier is used to control flow toward heat sink. Through experiments, the distance from leading edge of a heat sink to a flow barrier is varied for various bypasses under fixed volume flow rate condition. This study shows possibility to improve cooling performance when bypass and a flow barrier exist.
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We had proposed fast thermal stress estimation methodology for the components on system board when the system is stationary within specific ambient air temperature. Now, we will propose one efficient thermal stress estimation methodology, block adaptive filtering methodology, for the FPD electronic system board which is enclosed by mechanical cover.
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We demonstrate conformal phosphor coating and patterning methods on light emitting diodes (LEDs) using image processing based optofluidic maskless lithography (IP-OFML) system in microfluidic channels. IP-OFML allows a real-time detection and dynamic mask generation for packaging of randomly dispersed microchips. Our system detects each chip by considering rotation of the chip through image processing regardless of their arrangement error. Therefore, it precisely packages the chip making conformal polymer layer.
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We report on preparation of
$CaBaSiS_4:Eu^{2+}$ material by an advanced chemical solution method and fluorescent properties of the new material. The emission spectrum of$CaBaSiS_4:Eu^{2+}$ has the main peak centered at 598 nm, with the corresponding excitation maximum at around 420 nm. The strongest emission intensity of this material approached 96% compared to one of the best commercially available YAG:$Ce^{3+}$ phosphor. -
A novel blue emitting
$Ca_{1-x}Mg_2Si_3O_9:Eu_x$ phosphor was synthesized by the solid state reaction and its photoluminescence properties were optimized by controlling concentration of the activator contents and substituting concentration of Ca ion by Sr ion. The photoluminescence (PL) showed that this phosphor is efficiently excited by ultraviolet (UV)-visible light in the wavelength range from 200 to 410 nm. Also this phosphor emits intensely blue light with a broad peak at around 450 nm. -
The luminescence properties of a potential blue-emitting
$RbBaPO_4:Eu^{2+}$ phosphor substituted with various metal ions have been investigated. The main emission wavelength of the phosphor samples was red-shifted by the substitution with K and Sr ions. The maximum peak intensity was obtained from the sample$Rb_{0.25}K_{0.75}Ba_{0.99}Eu_{0.01}PO_4$ which showed 144% relative intensity versus that of BAM:$Eu^{2+}$ phosphor under 254 nm excitation. -
The structural and optical properties on
$Tb^{3+}$ addition into LiGd$(PO_3)_4$ compound were investigated by X-ray powder diffraction and photoluminescence spectroscopy. The emission spectrum shows the strongest peak corresponding to the$^5D_4{\rightarrow}^7F_5$ transition of$Tb^{3+}$ at 546 nm under 147 nm and 173 nm excitation. 85 mol% concentration of$Tb^{3+}$ for LiGd$(PO_3)_4$ is much higher than other Tb-doped phosphors. -
Three different fluoride compounds were used for preparation of
$BaAl_2S_4$ :Eu thin-films. The emission intensity of these devices were higher than that of the thin-films deposited without fluoride materials, and the appropriate annealing temperature decreased with fluoride dopants. It is related to the fluoride compounds accelerate the crystallization of$BaAl_2S_4$ at low temperature. -
Modified-polyol protocol was utilized for synthesis of green-emitting (
$^5D_4-^7F_j$ transitions of$Tb^{3+}$ ion) nanocrystalline$LaPO_4:Ce^{3+}$ ,$Tb^{3+}$ phosphors. Experimental parameters including chemical composition and annealing temperature were optimized to produce highly efficient, uniformly sized nanophosphors. Spin-deposited layer of$LaPO_4:Ce^{3+}$ ,$Tb^{3+}$ nanophosphors on glass substrate exhibited a transmittance of more than 80 %, indicating their efficacy for transparent display. -
The synthesis of nano-size (
$Y_{0.955}Eu_{0.1}$ )($P_{0.7}V_{0.45}$ )$O_4$ red phosphors were conducted by using a Liquid Phase Precursor (LPP) method. In this method, cellulose pulp was used as a template showing the micro fibre structures to obtain the nano size YPV red phosphor. Aqueous solutions of raw materials were impregnated into cellulose pulp and subsequently impregnated pulp was dried and fired at$800-1200^{\circ}C$ for 1h. The effect of luminescence properties on compositions and temperatures was evaluated with photoluminescence spectrum, X-ray diffraction and FE-SEM, and TEM. High efficiency (~110%) of phosphor of size of ~500nm fired at$1150^{\circ}C$ was obtained compared with the micro size of commercial product. High efficiency behaviors of nano size phosphors were discussed in this paper. -
A series of
$Eu^{2+}/Mn^{2+}$ co-activated$Ba_{1.98-x}Sr_xZnS_3$ red emission phosphors was synthesized using the polymerizable complex method. The excitation spectra of the materials contain two wide bands centered at 345nm and 445nm, implicating their possible use for white LED lighting applications. In addition, substitution of Sr for Ba by 20% (x=0.4) improved drastically the emission intensity as well as the internal quantum efficiency compared to those for Sr-free$Ba_2ZnS_3:Eu^{2+}/Mn^{2+}$ phosphor. -
Transparent
$Zn_2SiO_4:Mn^{2+}$ film has been synthesized by spray pyrolysis with various spraying conditions. It illuminates an efficient green emission with the relative emission intensity about 45% under 147nm excitation of a commercial powder phosphor. Additionally, the zinc precursors and additives play a key factor both controlling luminous efficiency and transparency. -
In order to apply to the White light emitting diodes (WLEDs), The
$Y_2SiO_5:Eu^{3+}$ as red phosphor was synthesized by solid state reaction method. The highest emission of$Y_2SiO_5:Eu^{3+}$ was shown when the$Eu^{3+}$ concentration was 0.02. A single phase was observed from X-ray diffraction (XRD) analysis of synthesized samples and secondary phase wasn't found. -
We have investigated the new modification of poly (vinyl phenol) (PVP) for low hysteresis organic thin film transistors (OTFTs). In order to suppression of hysteresis phenomenon, synthesized various backbone structure polymeric gate dielectric. The modified polymeric dielectric was synthesized by inducing ringshape phenol backbone structure instead of conventional chain. We could be observed that relieved hysteresis and excellent air stability from ring-shape phenol backbone structure.
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Fujii, Daiki;Sakamoto, Kunio;Nomura, Shusaku;Hirotomi, Tetsuya;Shiwaku, Kuninori;Hirakawa, Masahito 1308
The authors describe a 360 degree viewing display that can be viewed from any direction. To generate all-around 360 degree viewing window, we developed a sp ecial diffusion screen with one viewing aperture using holographic optical elements. -
Kanazawa, Fumihiro;Sakamoto, Kunio;Nomura, Shusaku;Hirotomi, Tetsuya;Shiwaku, Kuninori;Hirakawa, Masahito 1312
An olfactory display is a device that delivers smells to the nose. It provides us with special effects, for example to emit smell as if you were there or to give a trigger for reminding us of memories. The authors have developed a tabletop display system connected with the olfactory display. -
Nonideality of LED lens and diffuser as well as crosstalk between backlights should be compensated because they have large effects on image qualities. The computation complexities of conventional compensations are greatly increased as resolution becomes higher. The block based compensation is proposed to alleviate the computation complexity considering backlight profiles and image pixel characteristics.
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Rubbing effect on orientation of Copper Phthalocyanine for flexible organic field-effect transistorsCopper phthalocyanine (CuPc) Field-effect transistors (FETs) was successfully fabricated on plastic substrates. Orientation of CuPc crystallites on substrate could be obtained via rubbing process. It was revealed that CuPc crystallites were perpendicularly aligned on PES substrates with the rubbing direction. The performance of FETs was affected by orientation of CuPc on rubbed substrates.
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Adaptive black band insertion improve blur phenomenon that caused by hold type issue of LCD, the approach regulate charge time by OE signal to control black inserted ratio, and the charge time be modified according the motion quantity of displaying content.
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In large-area LCD displays, we have developed two new control technologies for high-power LED backlight. The Novel control technology called scanning control and local gray control. In addition, a conceptual display system power management was developed. We have implemented high power-LED module driving system which can achieve power saving and cost down. Finally, we designed LED light-bar module of the side type as a backlight source. It not only achieved light & thin but also reduced the quantity of LEDs.
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A 360-degree viewable three-dimensional display based on integral imaging is proposed. The cylindrically arranged point light source array which is generated by electroluminescent (EL) pinhole film reconstructs 360-degree viewable virtual 3D image at the center of the cylinder. In this paper, the principle of operation and experimental results are presented.
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Hosomi, Takashi;Sakamoto, Kunio;Nomura, Shusaku;Hirotomi, Tetsuya;Shiwaku, Kuninori;Hirakawa, Masahito 1334
The human vision system has visual functions for viewing 3D images with a correct depth. These functions are called accommodation, vergence and binocular stereopsis. Most 3D display system utilizes binocular stereopsis. The authors have developed a monocular 3D vision system with accommodation mechanism, which is useful function for perceiving depth. -
High resolution three-dimensional integral imaging display is proposed. Each time-multiplexed image is projected with different incident angle on same array of elemental lenses. Those images are collected at different positions in focal plane of lens array, and thus the number of the point light sources increases and their spacing decreases. Therefore, proposed method can create high resolution 3D images.
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A novel method to control the viewing direction by moving aperture location in 4-f illumination optics to control light direction is proposed. Based on integral imaging principle, the relayed point light sources by 4-f optics are modulated by a spatial light modulator, displaying three-dimensional images. In the proposed method, we locate the aperture, which acts as a band pass filter, around an optic axis to control the light direction. Resultantly, assuming that we know the viewer position by a tracking system, we can display appropriate three-dimensional images over large viewing angle.
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Ohara, Takashi;Sakamoto, Kunio;Nomura, Shusaku;Hirotomi, Tetsuya;Shiwaku, Kuninori;Hirakawa, Masahito 1345
We developed a glasses-free 3D stereoscopic display using an LCD display panel, a view control film and a grating film for stereoscopic viewing. The observer can watch overlapped stereoscopic images for left and right eyes without special glasses such as polarized glasses. -
Conventional depth extraction in integral imaging is based on the disparity information between the elemental images. Since the disparity is measured in pixel unit, however, the extracted depth is discrete, resulting in the quantization error. Moreover, the quantization error grows as the object depth increases, which limits the accuracy of the depth extraction for distant objects. In this paper, we propose a new method for depth extraction in integral imaging using sub-pixel registration information between subimages to obtain linear and accurate depth.
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In this paper, we explained characteristics of integral imaging microscope using point light source. To display the bio-medical information, which is captured as a form of the elemental images, using autostereoscopic displays, the characteristics analysis of three-dimensional information is required. For integral imaging microscope using point light source array, the elemental image capturing configuration has to satisfy a specific condition. We explain the condition to capture the elemental images and show the experimental results.
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In this study, the 0-th order diffraction could be efficiently removed with the obtained data for one hologram using the numerical reconstruction method. This method has a reduced data acquisition and processing time compared with the existing method wherein the data for two or more phase holograms are obtained for regeneration, and efficiently eliminates the 0-th order diffraction.
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We challenge to use reactive mesogen optical elements which can be coated inside LC cell. The reactive mesogens as retarder barrier requirements can be achieved between a high performance 2D mode and a low cross talk stereoscopic 3D mode. The fabrication of a 10.1" diagonal LCD which co-operates with a polarizer to from a parallax barrier, is described. In addition, the parallax barrier of reactive mesogens can easily control in mass production and can thus be coated as extremely LC cell, significantly reducing the thickness of LCD. Finally, we have successed to design a switchable 2D/3D displays using reactive mesogen optical elements which can be achieved 3D displays within glasses.
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A new recognition method is used to find the three-dimensional target object on integral imaging. For finding the location of a target image, amount of reconstructed reference image is needed. This method is giving accurate information of target image by correlated among reconstructed target images and reference images.
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Kim, Sun-Kyung;Park, Sang-Hyun;Kim, You-Jin;Min, Kwan-Sik;Park, Seo-Kyu;Jhun, Chul-Gyu;Kwon, Soon-Bum 1367
We have developed a 2D-3D convertible 7" autostereoscopic mini-monitor with high 3D quality, in which the parallax barrier LCD is attached on the TFTLCD. The excellent optical performance was achieved by design of the ghost free barrier and precise assembly between the barrier layer and the TFT-LCD panel. Our design principle and fabrication technology suppressed 3D cross-talk and improved viewing angle. In this paper, the design and fabrication process of the 3D mini-monitor are described. The evaluation for the 3D performance is also discussed. -
According to depth cues of an image, the optical engine of the solid volumetric true 3D display can project a sequence of slices of a 2D image to corresponding display at a set of liquid shutters (LC) locating at different depth. A single DLP optical engine developed for a solid volumetric true 3D display consists of a lamp, reflector, color wheel, hollow integrator, relays, DMD, and projection lens. The simulation results show that the optical engine designed for single DLP volumetric true 3D display satisfies the requirements.
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In this paper, a new method to efficiently generate the holographic news ticker in holographic 3DTV or 3-D movies using N-LUT method is proposed. The proposed method is largely consisted of five steps: construction of the LUT for each character, extraction of characters in news ticker, generation and shift of the CGH pattern for news ticker using the LUT, composition of hologram pattern for 3-D video and news ticker and reconstruct the holographic 3D video with news ticker. From some simulation results confirmed the feasibility of the proposed method in fast generation of CGH patterns for holographic news ticker.
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Lin, Chu-Hsun;Lin, Chun-Chuan;Lo, Hsin-Hsiang;Chung, Shuang-Chao;Chen, Tian-Yuan;Wang, Chy-Lin 1379
The 3D display has been used in optical projection technology to connect twenty mini- projectors with seamless image tiling. In this way, we can improve the projected resolution by reducing each project screen and increase projected area by connect several mini-projectors. In this article, the illumination system uses the LED light source, non- telecentric structure and LCOS panel, and it's total length is less than 10 centimeter. It can build a seamless large display by tiling multiple projectors. -
This paper suggests that testing method and equipment structure to detect potential failures of LCD cells. LCD Cell Aging Tester is the unique process to detect failures related with ASG circuits. This system consists of four components that is Aging chamber, work table, probe contact unit, and pattern generator. The key factor of the concept is temperature aging and HVS driving. Complicated combination of test parameters including voltage, temperature and frequency provided practical burn-in conditions eligible for prediction of mass production.
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We report on a new method of fabricating color filters based on selective wetting of color inks. The reversible formation of a hydrophobic layer provides sequential generation and protection of successive color filter patterns through a simple coating process. The transmittance and geometrical properties of the fabricated color filter were described.
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A series of new symmetric TTF derivatives were designed and synthesized. This facile synthetic method provides an opportunity to prepare TTF-based LC candidates. This series of compounds exhibited smectic A phase based on coplanar TTF core. One of the LC compounds was used as a semiconductor layer to fabricate OTFT.
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We once have announced that we developed a horizontal large-area alignment system with an alignment accuracy of <
${\pm}3{\mu}m$ and an alignment time of < 30 seconds, a core process module for RGB direct pattering by using a fine metal mask, which can process a Gen 4 ($730{\times}920mm^2$ ) substrate for high resolution OLED products. In this article, we presents a brand-new vertical alignment system for a even larger substrate of Gen 5 and beyond which can provide a better alignment accuracy and a higher throughput. The newly developed system exhibits an alignment accuracy of <${\pm}2{\mu}m$ and an alignment time of < 20 seconds which, we believe, can open a new era for manufacturing large-size OLED monitors and TVs. -
Ham, Yong-Hyun;Baek, Kyu-Ha;Park, Kun-Sik;Shin, Hong-Sik;Yun, Ho-Jin;Kwon, Kwang-Ho;Do, Lee-Mi 1399
In this article, we reported the results of etching polymonochloro-para-xylylene (parylene-C) thin films using inductively coupled plasma and$CF_4/O_2$ gas mixture. The$CF_4$ gas fraction increased up to the approximately 16 %, the polymer etch rate increased in the range of 277 - 373 nm/min. It confirmed that the etch rate of the parylene-C mainly depended on the O radical density in the plasma. Using a contact angle measurement, the contact angle increased with increasing the$CF_4$ fraction. Moreover, the contact angle was highly related a$CF_x$ functional group on parylene films. -
The silicon nitride films for gate dielectric were deposited by catalytic chemical vapor deposition at low temperature (
${\leq}200^{\circ}C$ ). The mixture of$SiH_4$ ,$NH_3$ and$H_2$ was used as source gases. The current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of the films were measured. The breakdown voltage and the flat band voltage shift of samples were improved by increase of the$NH_3$ contents and$H_2$ dilution ratio. The defect states were analyzed by photoluminescence (PL) spectra. As the defect states decreased, the breakdown voltage and the flat band voltage shift increased. -
We prepared polystyrene-b-poly(2-vinyl pyridine) (PSb-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer have 57 kg/mol-b-57 kg/mol. The result of UV-visible absorption spectra supported that effect of poly(ethylene oxide) on the band gap tuning of PS-P2VP photonic gel like salt effect.
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This paper describes organic acid-based wet chemical etching behaviors of amorphous Ga-doped zinc oxide (GZO) thin film sputter-deposited at low temperature (room temperature). Wet etch parameters such as etching time, temperature, and etchant concentration are investigated for formic and citric acid etchants, and their effects on the etch rate, etch residue and the feature of edge line are compared.
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It is suggested that the light extraction efficiency of the display device can be improved by adoption of periodic array of sub-wavelength scale structures. The relief of the total reflection has been investigated using the rigorous coupled wave analysis (RCWA). Various shape of the sub-wavelength scale structure allowed to have non vanishing transmittance for the light rays with the incident angle bigger than the critical angle.
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High transmittance and low resistance index matched transparent conducting oxide (IMTCO) coated glass was prepared and characterized. IMTCO was deposited by RF magnetron sputtering with the thickness of 15nm and 90nm thick anti-reflection layer was evaporated. To modify surface to hydrophilic, in-situ plasma treatment was also performed. IMTCO coated glass exhibited 96.6% of transmittance in the wavelength range of 400~700nm which is relatively high value compared to commercially available IMTCO glass. The sheet resistance uniformity was measured to be 1.53%.
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A series of new light-emitting random copolymers with fully conjugated structure was prepared, for the first time through the well-known Gilch polymerization between 1,4-bis(chloromethyl)-2-ethylhexyloxy-5-methoxybenzene and 2,5-bis(bromomethyl)thiophene monomers in different ratios. The synthesized polymers (on thin film) showed the maximum wavelength of UV-visible absorbance and photoluminescence (PL) near 500 nm and near 600 nm, respectively. A single-layer light-emitting diode device, which has a simple ITO (indium-tin oxide)/polymer/Al configuration, was fabricated by spin-coating of polymers and then vacuum evaporation of Al metal. The threshold bias of PMEHPVTVs was in the range of 3.5-10 V. As in the PL spectra, the maximum wavelength of light emission near 600 nm was also shown in electroluminescence (EL) spectra of PMEHPVTVs when the operating voltage was about 7 - 14 V.
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Modified self-assembled
$TiO_2$ and polyelectrolyte multilayer film have been used as OTFT insulator. Both films were used as gate insulator and their thickness were reduced to the order of 10nm. The operating voltage of OTFT was substantially reduced due to nanoscale thickness of titanium oxide and polyelectrolyte multilayer. Pentacene-based OTFT characteristics will be discussed. -
Lee, Chang-Ho;Kang, Jae-Kyung;Jang, Eun-Seok;Kim, Jae-Bum;Park, Joon-Ha;Shin, Jong-Keun;Chung, In-Jae 1425
In this paper, we investigated influence of gas pressure and gas mixing ratio on the abnormal discharge characteristics of fluorescent lamp. Abnormal discharge characteristics have been examined by changing inner gas pressure and mixing ratio. As the inner gas pressure and mixing ratio increase, the occurrence of abnormal discharge was delayed. It was found out that the occurrence of abnormal discharge is sufficiently delayed at the optimized inner gas pressure and mixing ratio. -
Ji, Seung-Hun;Youn, Hyun-Oh;Seo, Sung-Bo;Kim, Mi-Sun;Sohn, Sun-Young;Kim, Jong-Jae;Kim, Hwa-Min 1428
Compared to the indium zinc oxide (IZO) film fabricated by micro-powder target, the IZO film with nano-powder target exhibited improved optoelectronic properties of wide bandgap, high transmittance, surface uniformity, and low sheet resistance due to the high film density. -
The effect of different annealing methods on the sheet resistance of indium tin oxide (ITO) on polyimide (PI) substrate has been investigated. As electro-annealing induced the predominant growth of crystallites of ITO thin films along (400) plane, the sheet resistance of ITO films that were electro-annealed for 2 mA at
$180^{\circ}C$ considerably decreased from 50 to 28${\Omega}/cm^2$ . -
Film morphology, crystallinity, and luminescence property of solution processed ZnO films have been studied. Fluorine addition and annealing ambient significantly change the defect-related emission band as well as the structural property. Using the overall emission behaviors, we can predict an optimized process condition for solution-based ZnO thin film.
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Electrical and optical properties of
$SiO_2$ -doped ZnO (SZO) films on the corning 7059 glass substrates by using rfmagnetron sputtering method are investigated. The deposition rate becomes maximum near 3 wt.% and gradually decreases when the$SiO_2$ content further increases. The growth rates at 3 wt.% is$4^{\circ}$ A/s. We found that the average transmittance of all films is over 80% in the wavelength range above 500 nm. The optical band gap decreases from 3.52 to 3.33 eV with an increase in thickness. X-ray diffraction patterns show that the film with a relatively low$SiO_2$ content (< 4 wt.%) is amorphous. SZO films at the$SiO_2$ contents of 2 wt.% shows the resistivity of about$3.8{\times}10^{-3}{\cdot}cm$ . The sheet resistance decreases with increasing the heat treatment temperature. -
We have devised a methodology based on the concept of foveal (or parafoveal) vision to investigate viewing angle related mura of a backlight unit (BLU). Three different cases of mura phenomenon in BLUs are studied with optical simulation software ASAP in this work. Simulation results, illuminance comparisons between emitting light from BLUs without and with "angle sorting" as well as experimental results are presented. They show good agreement between simulations and experimental observations that demonstrates the method's validation and robustness.
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The atmospheric pressure plasma polymerization of acrylate monomers was carried out to have dielectrics with easy preparation and high performance. The effects of discharge power, monomer concentration and deposition time on film properties were investigated using various characterization tools. With proper conditions, smooth dielectric layer of 100nm thickness was obtained. Dielectric property as organic dielectric layer has been studied for future applications in organic thin film transistors(OTFT).
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We report the syntheses bis-(N,N-diethylaminoethyl) perylene-3,4,9,10-tetracarboxylic diimide (PDI) of lyotropic chromonic liquid crystal and it dissolves in photocurable ionic monomer solution. PDI-acrylic acid solution was observed whether liquid crystal phase appeared in each concentration. Thin film polarizer was prepared by simultaneously coating and aligning the solution of PDI-acrylic acid (in the chromonic nematic phase) onto glass substrates using a mechanical shearing force and was cured by irradiation of UV light. Also Photopatterned polarizer is manufactured by same process.
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In this work, a plastic diffuser which has a surface similar to Sinusoidal wave profile for application of LC D backlighting is proposed. This new pattern diffuser is achieved the values of the transmission efficiency an d diffusion efficiency all over 70%, and it also has the value about gain over 1.1. Additionally, this new patter n diffuser has high uniformity when we put it in the LCD backlight module and its thickness is only 2mm. With these foregoing properties, this diffuser film can widely applied to LCD displays systems etc.
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Transparent sol-gel hybrid dielectric material (hybrimer) coating films were fabricated by spin coating and photo or thermal curing of sol-gel derived oligosiloxane resins. Hybrimer coating films are suitable as the passivation layer of TFT in AMLCD due to low dielectric constant, small loss tangent, low leakage current density, high transmittance and thermal stability.
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The fundamental parameters controlling ink-jet printing liquids are the viscosity and surface energy. The wetting contact angle determines the spread of a liquid drop on the surface and depends on the relative surface energy. The characteristics of silver ink-jet printing were studied with control of surface energy and head temperature. Polyethylene terephthalate(PET) film and Si-wafer(ptype) were used as substrates and atmospheric plasma was treated to control the surface energy. With silver ink, the hydrophilic surface treatment could reduce the radius of droplets due to the hydrophobic nature of silver ink.
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In this study, we prepared the multi-refraction film thin by ink-jet technique with sol-gel precursor. The precursors were prepared by using some transition metal alk-oxide and the tetraethylorthosilicate (TEOS) mixed separately with n-Butyl Alcohol and PVB (Poly(vinyl butyral)).The structure and morphology of the resulting films were investigated by atomic force microscope (AFM). It is shown that the shape of the pattern of the films would affect the refraction proportion.
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Because of its weak points that narrow viewing angle and grayscale inversion, 'bare' twisted nematic (TN) LCD has some limits to use as a display device, though its great strong points that low cost, high yield, simple design, high transmittance and normally white. The 'WideView(WV)' film which introduced by Fuji co., has been good solution to extend the viewing angles of TN mode, therefore that film have been used generally for TN panels needed wide viewing angle. This paper introduce the research to find the parameters of the Wide view film and a TN panel which affect viewing angle characteristics and how to adjust those parameters.
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The preparation method of copper nanopowder by dry process for conductive ink was investigated. Inert gas condensation method was used to synthesize copper nanopowder. The produced powders was spherical and sized 10~100nm flowing the conditions. The results showed that input voltage and evaporation rate is critical variables for nano-sized copper powder.
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Effect of contamination of liquid crystal on the electrical behavior of liquid crystal display (LCD) by spilled components from color filter layer was investigated. It is noted that the level of contamination was different following the kind of liquid crystal and organic layers. Transmittance curve of LCD cell was shifted by spilled components of color filter and BM materials. C-V curve also showed different behavior following color filter type. The results obtained show the image sticking of LCD can be varied by pairing liquid crystal with color filter materials.
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The microfluidics channel were fabricated using thermal roll-imprinting process on plastic substrates. As rollimprinting surface is heated directly at
$100^{\circ}C$ and printing process proceed 380/400 kgf pressure, we fabricated microfluidic patterns separated line of$40.04{\mu}m$ , serpentine line of$113.89{\mu}m$ and depth of imprint pattern is$15.35{\mu}m$ , it means to get fine pattern has more than 70% imprint rate in designed mask. -
Kim, Myong-Ki;Shin, Kwon-Yong;Lee, Sang-Ho;Hwang, Jun-Young;Kang, Heui-Seok;Kang, Kyung-Tae 1476
The characteristics of polymer inkjet printing were investigated systematically in this paper. PEDOT/PSS as a hole injection layer and MEH-PPV as a light emitting layer were used for inkjet printing experiment. Inkjet head controlling technology and surface modification technology were also applied for polymer inkjet printing. With the developed polymer inkjet printing technology, OLED(Organic Light Emitting Display) was successfully fabricated and demonstrated. -
Lee, Sang-Hyuk;Seo, Bo-Hyun;Lee, In-Kyu;Seo, Jong-Hyun;Lee, Kang-Woong;Jeon, Jae-Hong;Choe, Hee-Hwan;Ryu, Jong-Hyeok;Park, Byung-Woo;Chang, Dae-Hyun 1479
Compared with tilt transfer wet station, vertical etching system has a variety of advantages that are 50% space savings, higher throughput, fairly good etch uniformity over an entire glass for thin film transistor application. The aim of the present work is to study on a vertical etching system to improve the process factors. The computational fluid dynamics analysis is used to demonstrate the change of the etch uniformity as a function of tilt angle of the glass substrate. -
Silicon dioxide (
$SiO_2$ ) thin films were deposited using a modified DBD called a "pin-to-plate-type DBD" in order to generate high-density plasmas with a gas mixture of PDMS/$O_2$ . The effect of the gas mixture on the physical and chemical properties of$SiO_2$ deposited by the pin-to-plate-type DBD with the mixture of PDMS/$O_2$ was investigated. -
Micro wall is fabricated using iterative screen printing that it is able to fabricate the pattern as low cost, simple process, formation of pattern at large area on the various substrates. In the process of micro wall fabrication using screen printing, the printing result with pressure change in process and improvement of surface roughness using hydrophillic plasma treatment are included. Height of micro wall increase linearly and precision of iteration is very high. Error rate of printed pattern width is very high, but change rate of width is under 10 %. Fabricated micro pattern have minimum width
$48.75{\mu}m$ and maximum height$75.45{\mu}m$ with aspect ratio 1.55. -
In this work we present a new type of line plasma source using an internal-type ICP operated at 2MHz with a ferrite module, describe the effect of ferrite module on the enhancement of the plasma properties and the uniformity, and compare to those obtained with 13.56MHz discharge. Also the electrical characteristics of the antenna line and the characteristics of the plasma uniformity were studied.
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Kim, Bong-Jin;Kim, Hyung-Jun;Jung, Sung-Mok;Yoon, Tae-Sik;Kim, Yong-Sang;Choi, Young-Min;Ryu, Beyong-Hwan;Lee, Hyun-Ho 1494
Thin Film Transistor(TFT) having CIS (CuInSe) semiconductor layer was fabricated and characterized. Heavily doped Si was used as a common gate electrode and PECVD Silicon nitride ($SiN_x$ ) was used as a gate dielectric material for the TFT. Source and drain electrodes were deposited on the$SiN_x$ layer and CIS layer was formed by a direct patterning method between source and drain electrodes. Nanoparticle of CIS material was used as the ink of the direct patterning method. -
Li, Zhao-Hui;Ahn, Min-Hyung;Choi, Kyung-Min;Im, Seung-Hyeok;Jung, Kyung-Seo;Cho, Eou-Sik;Kwon, Sang-Jik 1496
A diode-pumped Nd:$YVO_4$ laser was used to obtain indium tin oxide (ITO) patterns on glass substrate with various overlapping rates. The results showed that the overlapping rate of laser beam influences on the edge structure of ITO pattern and the surface roughness of ablated groove bottom. At a laser repetition rate of 40 kHz, the optimized condition of overlapping rate was 75 %. -
In this paper, we studied about atmospheric pressure remote plasma ashing of photoresist(PR), by using a modified dielectric barrier discharge(DBD). The effect of various gas combinations such as
$N_2/O_2$ ,$N_2/O_2+SF_6$ on the changes PR ashing rate was investigated as a function of power. The maximum PR ashing rate of 1850 nm/min was achieved at$N_2$ (70 slm)/$O_2$ (200 sccm) +$SF_6$ (3 slm). We found that as the oxygen and fluorine radical peaks were increased, the ashing rate is increased, too. -
In this paper, the etching behavior of ZnO in
$CF_4$ plasma mixed Ar was investigated. Previously, the etch rate in$CF_4$ /Ar plasma was reported that it is slower than that in Cl containing plasma. But, plasma included Cl atom can produce the by-product such as$ZnCl_2$ . In order to solve this film contamination, no Cl containing etching gas is required. We controlled the etching parameter such as source power, substrate bias power, and$CF_4$ /Ar gas ratio to acquire the fast etch rate using a ICP etcher. We accomplished the etching rate of 144.85 nm/min with the substrate bias power of 200W. As the energetic fluorine atoms were bonded with Zinc atoms, the fluoride zinc crystal ($ZnF_2$ ) was observed by X-ray photoelectron spectroscopy (XPS). -
In this work, we have compared OLED devices made of blended MEH-PPV/Ruburene mixture and MEH-PPV/Rubrene bi-layer structure devices. The emission layers were made with two different ways - one with gravure printed single layer of blended mixture of MEH-PPV and rubrene, the other with gravure printed bilayers of MEH-PPV and rubrene. Both brightness and efficiency with gravure printed bi-layer devices were higher than blended devices. In this work, we demonstrated that organic bi-layers can be formed with gravure printing technology and higher efficiency can be achieved with bi-layer structure than with blended single layer structure.
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Organic light emitting layer in OLED device was formed by gravure printing process in this work. Organic surface coated by gravure printing typically showed relatively bad uniformity. Thickness and roughness control was characterized by applying various mixed solvents in this work. Poly (N-vinyl carbazole) (PVK) and fact-tris(2-phenylpyridine)iridium(
$Ir(ppy)_3$ ) are host dopant system materials. PVK was used as a host and Ir(ppy)3 as green-emitting dopant. To luminance efficiency of the plasma treatment on etched ITO glass and then PEDOT:PSS spin coated. The device layer structure of OLED devices is as follow Glass/ITO/PEDOT:PSS/PVK+Ir(ppy)3-Active layer /LiF/Al. It was printed by gravure printing technology for polymer light emitting diode (PLED). To control the thickness multi-printing technique was applied. As the number of the printing was increased the thickness enhancement was increased. To control the roughness of organic layer film, thermal annealing process was applied. The annealing temperature was varied from room temperature,$40^{\circ}C$ ,$80^{\circ}C$ , to$120^{\circ}C$ . -
Hydrophobic treatments were conducted for different kinds of substrates, glass substrate, silicon wafer and plastic substrate. Ar-
$CH_4$ gas mixture was used as a discharge gas for the hydrophobic treatment. The change of the contact angle before and after treatment was measured and compared. Time evolution of the contact angle change after hydrophobic treatment was investigated. -
We describe a 32" liquid-crystal display (LCD) with multi-touch sensing capability by integrating IR detector arrays onto the LED backlight plate. A transparent light guide is placed in front of the display screen, with IR LEDs disposed at its edges and emitting IR light into the light guide, the light is trapped by total internal reflection within the light guide to be as touch-sensing light. A physical contact with the acrylic plate surface will stimulate some trapped light to be escaped from the light guide and pass through LCD panel to be detected by the IR detectors. The touch-sensing LCD with this configuration can locate simultaneous multiple touche points on the touchable surface.
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We present highly polarized light emissions from an OLED on a flexible photonic anisotropic substrate. It was found that the polarization direction of emitted electroluminescent light corresponded to the ordinaryaxis of the photonic anisotropic substrate. Furthermore, it was also found that luminous polarized electroluminescence over 4,500 cd/
$m^2$ was produced with high peak efficiency of 6 cd/A and high polarization ratio over 25. -
Do, Yun-Seon;Yang, Kee-Jeong;Sung, Shi-Joon;Kim, Jung-Ho;Lee, Gwang-Jun;Lee, Yong-Hwan;Chung, Hoon-Ju;Roh, Chang-Gu;Choi, Byeong-Dae 1527
A LCoS micro-display using polymer dispersed liquid crystals (PDLCs) for light switching layer was fabricated. The Si backplane of SVGA ($800{\times}600$ ) with a pixel size of$14{\times}14mm^2$ was prepared by a$0.35{\mu}m$ 18V CMOS process. PDLCs were filled in the gap between backplane and ITO glass by conventional vacuum filling method. The prepared panels were driven by a field sequential color (FSC) scheme at the frequency of 180Hz and were successful in modulating LED lights to show projection images. The preparation and performance of PDLC-LCoS are presented. -
Effect of process factors on the sensitivity of inner-type digital switching TSP was analyzed. From these results, we have successfully fabricated inner-type digital switching TSP embedded in 3.2-inch WQVGA PLS mode LCD panel. During many factors, TFT sensor structure for reducing the PI thickness and a separation distance of
$0.3{\mu}m$ between the conductive column spacer (C/S) and TFT sensor were essential. Glass thickness and main C/S density were also important factors. This technology can be applied to wide angle of view hand-held phones, personal digital assistants (PDAs), and tablet PCs. -
High performance resistive type touch panel was fabricated on flexible polyethylene terephthalate (PET) substrates coated with Al- and Ga-codoped ZnO (AGZO) films. The AGZO films were deposited by roll-to-roll direct current magnetron sputter at room temperature. The AGZO thin films on PET substrates showed high transparency (> 85 % at 550 nm) and low sheet resistance (450
${\Omega}$ /sq.). These values were similar to those of commercial ITO films used for resistive type touch panel. -
Amphiphobic thin films for touched panel application was prepared by
$SiO_2$ nanoparticles self-assembled nanostructure. Silicon dioxide nano spheres were prepared by sol-gel method and well dispersed in a solution with surfacants of low surface energy. Nanostrcture thin films were obtained by spin coating technologies. -
Ahn, Min-Hyung;Li, Zhao-Hui;Choi, Kyung-Min;Im, Seung-Hyeok;Jung, Kyung-Seo;Cho, Eou-Sik;Kwon, Sang-Jik 1542
For the application of flexible substrate to future display and new transparent devices, indium tin oxide (ITO) thin film was formed on polycarbonate(PC) substrate at room temperature by in-line sputter system. During the ITO sputtering, Ar and$O_2$ reaction gas were fixed at a constant value and the process pressure was varied from 3 to 7 mtorr. From the electrical and the optical properties of sputtered ITO films, the sheet resistances of as-deposited ITO films varied with a different pressure and the optical transmittances of the ITO films at visible wavelength were maintained above 85%. The results are considered to be due to the saturation of$O_2$ atoms from reaction in ITO film. -
In recent studies on tone reproduction with the objective of reproducing natural looking colors in digital images, an integrated multi-scale retinex (IMSR) has produced great naturalness in the resulting images. Most methods, including IMSR, work in RGB or quasi-RGB color spaces. As such, this produces hue distortion from the perspective of the human visual system. Accordingly, this paper proposes the hue preserved multi-scale Retinex (HPMSR) method to obtain a high contrast and naturalness. The proposed method enhanced the
$L^*$ and saturation values in CIELAB color space. As a result, the visibility in dark shadows in the resulting images was improved. -
We studied the human visual performance with PDP and LCD to clarify the relationships between viewer preference and chromatic adaption. In this paper, optical performance of the display is measured mechanically based on standard. The human visual performance about the display color image quality trough optical process is represented numerically based on CIECAM02. By comparing these results with the result of the questionnaire, performance of the display can be evaluated in detail.
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In this paper, we propose a system to adjust specific color of image. The HSV of R/Y/G/C/B/M regions can be modified individually. The color reproduction can be preferred color, true color, or stander color for customer requirement.
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By using optimum doping ratio (10 ~ 20 wt%) of glycerol, the power conversion efficiency (PCE) of organic photovoltaic devices based on poly (3-hexylthiophene) and phenyl-
$C_{61}$ -butyric acid methyl ester was dramatically increased from 3.23% to 5.03%. Finally, semitransparent organic photovoltaic devices including glycerol doped poly (3,4-ethylenedioxy-thiophene):poly (styrene sulfonate) and thin Ag (< 1 nm) buffer layer typically have shown PCE > 3% with transmittance > 30% in visible ranges. -
We fabricated Dye-Sensitized Solar Cells(DSSCs) which are modified by using liquid crystals(LCs) and electro-deposition on cathode electrode in order to apply to flexible DSSCs. We deposited Pt metal layers on ITO electrode through the method of electro-deposition process during low-temperature. We could expect the long-term stability by using ionic liquid(IL) and liquid crystals(LCs). We can also see the enhancement of efficiency through orientation of LCs in gel-state electrolyte using liquid crystals at the DSSCs.
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Cu(In,Ga)
$Se_2$ Absorber Layer Prepared by Electron Beam Evaporation Method for Thin Film Solar CellLi, Zhao-Hui;Cho, Eou-Sik;Noh, Gap-Seong;Lim, Jae-Eok;Pahk, Heui-Jae;Bae, Kyung-Bin;Kwon, Sang-Jik 1564
Cu(In,Ga)$Se_2$ (CIGS) thin films were formed using CIGS bulk by electron-beam evaporation method with an evaporation current from 20 mA to 90 mA. The experimental results showed that the chemical compositions and the properties of CIGS films varied with the different evaporation current. The Cu-rich CIGS film was deposited successfully with a band gap of 1.20 eV when the evaporation current was 90 mA. -
Nanocrystalline silicon thin films were deposited using an internal-type inductively coupled plasma-chemical vapor deposition at room temperature by varying the bias power to the substrate and the structural characteristics of the deposited thin film were investigated. The result showed that the crystalline volume fraction was decreased with the increase of bias power. At the low bias power range of 0~60 W, the compress stress in the deposited thin film was in the range of -34 ~ -77 Mpa which is generally lower than the residual stress observed for the nanocrystalline silicon thin films deposited by capacitively coupled plasma.
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Polymer solar cells were fabricated with gravure printing process and the effect of thermal annealing of gravure printed organic layer was investigated. The layer structure of polymer solar cells is glass / ITO / hole transfer layer / active layer / Al structure was fabricated. For the active layer, 1:1 ratio of poly-3-hexylthiophene (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) mixture was applied. The P3HT/PCBM blend was gravure printed onto the substrates. The effect of thermal annealing was investigated by changing annealing time and the number of printing. Maximum 3.6% of power conversion efficiency was achieved with gravure printing of organic layer and thermal annealing in this work.
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Fullerene/polystyrene nanoparticles having the average size of 300 nm ~ 1
${\mu}m$ were prepared by emulsion polymerization in aqueous medium. Poly(vinyl pyrrolidone) and potassium persulfate were used as a dispersant and an initiator, respectively. The contents of fullerene in the nanoparticle were controlled to be from 10 to 57 wt% by varying the feed ratio, which was confirmed by IR-spectroscopy, thermogravimetric analyses, and elemental analyses. Dynamic light scattering experiments revealed the particles have a broad size distribution. Further characterizations of the nanoparticles were performed by using SEM and TEM observation. The high content of fullerene in the particles will find applications in photovoltaic and organic semiconducting area. -
We have investigated the characteristics of transparent indium zinc oxide(IZO)/Ag/IZO multilayer electrode grown on polyethylene terephthalate (PET) substrates using a specially designed roll-to-roll sputtering system for use in flexible device are described. By the continuous R2R sputtering of the bottom IZO, Ag, and top IZO layers at room temperature, we were able to fabricate an IZO-Ag-IZO multilayer electrode with a sheet resistance of 6.15
${\Omega}$ /square, optical transmittance of 87.4 %, and figure of merit value of 42.03 10-3${\Omega}$ -1. In addition, the IZO-Ag-IZO multilayer electrode exhibited superior flexibility to the RTR sputter grown single ITO electrode, due to the existence a ductile Ag layer between the IZO layers. This indicates that the RTR sputtered IZO-Ag-IZO multilayer is a promising flexible electrode that can substitute for the conventional single ITO electrode grown by bath type sputtering for use in low cost flexible device, due to its low resistance, high transparency, superior flexibility and fast preparation by the R2R process. -
This work describes a power and area efficient switched-capacitor cyclic DAC for mobile display drivers. The proposed DAC can be simply implemented with one opamp two capacitors and several switches. Furthermore, the op-amp input referred offset is attenuated at the DAC output without additional offset cancellation circuitry. The operation of the cyclic DAC is verified through circuit level simulations.
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The effects of bias stress on spin-coated zinc tin oxide (ZTO) transistors are investigated. Applying a positive bias stress results in the displacement of the transfer curves in the positive direction without changing the field effect mobility or the subthreshold behavior. Device instability appears to be a consequence of the charging and discharging of temporal trap states at the interface and in the zinc tin oxide channel region.
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We investigated the influence of chemical compositions of gallium and indium cations on the performance of solgel derived amorphous gallium indium zinc oxide (a-GIZO) based thin-film transistors (TFTs). Systematical composition study allows us to understand the solutionprocessed a-GIZO TFTs. Understanding of the compositional influence can be utilized for tailoring the solution processed amorphous oxide TFTs for the specific applications.
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The ubiquitous nature of large area TFT-LCD televisions are truly one of the major success stories of consumer electronic products for the
$21^{st}$ century. It is the industry's ability to lower prices over the years that have made TFT-LCD television an affordable option for the majority of consumers. TFT-LCD equipment manufacturers have played a major role these cost reduction efforts. Increasing requirements for high process quality like for eg UHD panels need to be met simultaneously with the demand of an highly productive and reliable equipment. AKT provides an excellent PVD product by improving performance and cost of ownership (CoO) for Gen8.5 and beyond. -
Yamamoto, Shin-Ichi;Haseba, Yasuhiro;Iwata, Takashi;Higuchi, Hiroki;Choi, Suk-Won;Kikuchi, Hirotsugu 1593
We demonstrate an intriguing liquid crystal display (LCD) mode that comprises an optically isotropic liquid crystal (LC) composite incorporating with inplane electric field geometry. No surface treatment, such as rubbing, is required to fabricate the LCD mode because it is based on an optically isotropic state. The measured response time was of submillisecond order. The LCD mode has several unique features such as fast response, continuous grayscale capability, and a high contrast ratio. -
Mobile ODF (one drop filling) portable display such as mobile phone and application product is needed high reliability than notebook, monitor and TV. Therefore, material development in order to optimize mobile & application ODF panel is needed. Through considering mobile ODF process and design, we have developed method of material matching test by several tests which is heat stress, UV stress and ODF process condition. So we have developed a material with characteristics of high reliability for mobile ODF panel.
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Shin, Hong-Sik;Yun, Ho-Jin;Nam, Dong-Ho;Choi, Kwang-Il;Baek, Kyu-Ha;Park, Kun-Sik;Do, Lee-Mi;Lee, Hi-Deok;Wang, Jin-Suk;Lee, Ga-Won 1600
In this work, we have fabricated inverted staggered ZnO TFTs with 1-${\mu}m$ resolution channel length by micro contact printing (${\mu}$ -CP) method. Patterning of micro scale source/drain electrodes without etching is successfully achieved by micro contact printing method by using silver ink and polydimethylsiloxane (PDMS) stamp. And the time dependent characteristics of the sheet resistance show that Ag inklayer could be used as source and drain electrodes for ZnO TFTs. -
YAG laser crystallization of Si-based thin film deposited on plastic substrate has been studied. The Si-based thin films as crystallization precursor are with varied hydrogen (H) content. The effect of the H content on the crystallinity of the resulted poly-Si film has been investigated. The experimental results of the poly-Si crystallized by doublefrequency YAG laser shows that the initial dehydrogenation process could be left out if
${\mu}c$ -Si was adopted as the crystallization precursor. The YAG laser annealing condition on plastic substrate and the crystallization results have been discussed in the paper. -
Li, Juan;Chong, Luo;Ying, Yao;He, Li;Meng, Zhiguo;Chunya, Wu;Xiong, Shaozhen;Kwok, Hoi-Sing 1608
Here the hydrogen passivation treatment has been adopted to enhance the performance of poly-Si crystallized by YAG laser annealing (LA poly-Si). We have investigated the effects of passivation time, passivation power and passivation temperature on the hall mobility of the LA poly-Si and analyzed the mechanism of the hydrogen passivation preliminary. It has been found that the quality of the poly-Si annealed by YAG laser could be improved after proper hydrogen plasma treatment.