한국정보디스플레이학회:학술대회논문집
The Korean Infomation Display Society (KIDS)
- Annual
Domain
- Electricity/Electronics > Display
2008.10a
-
The TFT-LCD industry has shown dramatic growth by making technological advances and satisfying consumer needs. It now stands at the heart of the display industry. However, the TFT-LCD market is maturing and is unlikely to sustain the fast pace of growth in years to come. There has been an oversupply in the LCD sector entering 2008 due to capacity expansion aimed at fueling growth coupled with softening demand amid the global economic slowdown and recent financial turmoil. The LCD industry has successfully coped with oversupply on several occasions. Each time, LCD makers faced up to the challenge and responded with a pioneering spirit. They continued to grow by turning crisis into opportunity. LG Display aims to create new markets by developing products based on innovative technology and providing more attractive products through a value-added product planning that incorporates consumer needs. Through a continuous cost innovation targeted at stimulating demand by making products more economical to consumers, we will be at the forefront of overcoming the current oversupply and sustaining robust growth for the TFT-LCD industry. Depending on our management of the situation, the current oversupply could prove to be an opportunity to create even bigger markets for the future.
-
The progress in flat panel displays over the last two decades has been astonishing. In just 20 years, the LCD-TV grew up from a 2-inch curiosity, to an industry that will sell about 120 million flat panel TV's this year, with viewing area up to 4000 times larger. That success is based on continuous innovation, especially in manufacturing processes. For the next decade to bring another doubling of the business, progress will need to continue in four major areas: Human factors, ecological impact, visual quality, and of course continued drive towards affordability. This talk will detail the technology advances that can allow this industry to meet those challenges. Human factors. Today, we adapt our lifestyle to our technology. People organize their offices, and their homes, around displays. We pass around mobile phones to share images, rather than experiencing them as a group. Billions of newspapers continue to be sold daily. Advances in flexible displays can lead to large portable displays. "New era projection" includes the handheld Pico Projectors that are already on the market, and will ultimately appear integrated in mobile phones the same way cameras do today. "Eco" impact. Today TV's are one of the top energy consumers in a U.S. home, and the fastest growing. Watching a large flat panel TV can cost twice as much as running a large refrigerator. With today's concern about energy consumption, regulations are starting to emerge worldwide to limit TV electrical use. Fortunately, good solutions exist in using light management films to eliminate bulbs, saving power without increasing cost. Going forward, LED backlights will drive another step downward. OLED displays might be the ultimate solution. Visual quality. The color of an LCD-TV is still often considered inferior to a far less expensive CRT. And almost all displays suffer from representing a three-dimensional world on a two dimensional surface. The technology to improve color is available today, and will likely move from premium sets into the mainstream as costs come down. 3D is now arriving in movie theaters worldwide, and that will drive up the demand for similar realistic images in home theaters. And the technology is emerging today for 3D representation to move beyond specialized applications into everyday use, on screens large and small. Affordability. The world takes cost-down miracles for granted in consumer electronics. Each of these other advances will be balanced with a drive for affordability, especially as the market grows in emerging countries. The other three challenges must be met without increasing cost. Putting this all together, the next few years will emphasize "eco friendly" designs, and enhanced images such as 3D. By 2013 we will start to see serious penetration by emissive technologies (OLED, high efficiency plasma, or other), with the "ultimate display" likely not in the market for a decade. Lots of opportunities for innovation remain ahead of us.
-
Research and development on flexible electronic displays has gone on for over 20 years. Despite this history, very few flexible displays have entered the marketplace. I will discuss the history of development of flexible display technology and the technical and market forces that have slowed the commercialization of this technology.
-
For the large-sized and post-ultra definition TFT-LCD, improved drivability is prerequisite not only for the integration of driving circuit on glass but also for the chargeability of each pixel. In order to meet required drivability, currently adopted process architecture and materials are modified for the RC delay reduction, including the drastic increase of gate bus thickness and its related solution for step coverage. We present new process architecture and material selection for the next generation TFT-LCD devices.
-
Mobile phones are evolving into a platform for internet access. In order to display web pages in handsets, WVGA and around 3-inch displays are strongly recommended. Low power consumption, compactness and narrow boarder area are essential. The general requirements for WVGA solution and the design factors to reduce the power consumption and boarder area discussed.
-
An advanced TFT-LCD structure was proposed to increase aperture ratio (AR). In this structure, metal layers formed below the data lines are used as light-blocking layers, achieving higher AR ratio than that of a conventional structure. Since average misalignment between the metal light-blocking layers and pixel electrodes is smaller than that of black matrixes on color filter glass, substantially less light-blocking areas are needed to achieve misalignment margin. The AR of the LCD panel fabricated by using proposed structure was enhanced by 18.7 % over that of the conventionally structured panel.
-
We proposed a-Si:H TFT (hydrogenated amorphous silicon thin film transistor) level shifter which reduced number of power sources. To reduce the number of power sources from four to two, modified bootstrapped inverter was used for the level shifter. The shift register was verified by PSPICE circuit simulation and fabricated. The fabricated level shifter successfully shifted low input (0 to 5 V) to high level output (-7 to 23 V).
-
Announcements by many companies have shown that market interest and technical potential exist for AMOLEDs. DuPont Displays is developing solution processing technology designed to address the high cost of manufacturing AMOLEDs via vapor deposition methods. By printing OLED displays, we can reduce costs and can subsequently scale OLED manufacturing to a competitive motherglass size.
-
Kim, Sun-Young;Park, Tae-Jin;Jeon, Woo-Sik;Kim, Jong-Sil;Pode, Rachamdra;Jang, Jin;Kwon, Jang-Hyuk 30
Using a$Ir(ppy)_3$ doped in hole and electron transport host materials, simple three layers green PHOLEDs comprising double emissive layers have been fabricated. A low driving voltage value of 3.3 V to reach a luminance of$1000\;cd/m^2$ and maximum current- and power-efficiency values of 53.9 cd/A and 57.8 lm/W are demonstrated in this simple structure phosphorescent OLED. -
Highly efficient red and green phosphorescent devices comprising a simple bilayer structure are reported. The driving voltage to reach
$1000\;cd/m^2$ is 4.5 V in$Bebq_2:\;Ir(piq)_3$ red phosphorescent device. Current and power efficiency values of 9.66 cd/A and 6.90 lm/W in this bi-layered simple structure PHOLEDs are obtained, respectively. While in$Bepp_2:Ir(ppy)_3$ green phosphorescent device, the operating voltage value of 3.3V and current and power efficiencies of 37.89 cd/A and 35.02 lm/W to obtain a luminance of$1000\;cd/m^2$ are noticed, respectively. -
We have developed new display techniques that allow presentation of nearly correct focus cues. Using these techniques, we find that stereo vision is faster and more accurate, and that viewers experience less discomfort, when focus cues are consistent with simulated depth.
-
This study investigated if a requirement for screen gloss is needed in the TCO Requirements and was, therefore, targeted towards finding an acceptable reflex level. The results show that a glossy surface has an impact on the visual ergonomics, and for this reason we believe that a requirement is needed. Although, the results do not point to a single value that is better than another, so a selection for a requirement level has to be augmented with additional information. Such a discussion is given and 60 gloss units at 60 degrees (
$GU_{60}$ ) was selected as the new requirement level for the TCO Requirements (TCO '03 and TCO '05). -
Chong, Jong-Ho;Lee, Seung-Bae;Park, Hye-Ryoung;Kim, Sang-Ho;Bae, Jae-Woo;Kim, Hye-Dong;Kim, Hun-Soo 47
We propose a new method evaluating the image quality of display devices using the CIECAM02 that is the recently developed CIE color appearance model and provides an extension of the previously recommended CIE color spaces. We develop the evaluation method that quantifies the color reproduction capability, emotional gray scale (gradation), and visual perception contrast (perceptual contrast range) based on the gamut in this model. -
In this paper, we propose a practical method for displaying 2D/True3D mixed contents in real-time. Many companies released their 3D display recently, but the costs of producing True3D contents are still very expensive. Since there are already a lot of 2D contents in the world and it is more effective to mix True3D objects into the 2D contents than making True3D contents directly, people became interested in mixing 2D/True3D contents. Moreover, real-time 2D/True3D mixing is helpful for 3D displays because the scenario of the contents can be easily changed on playback-time by adjusting the 3D effects and the motion of the True3D object interactively. In our system, True3D objects are rendered into multiple view-point images, which are composed with 2D contents by using depth information, and then they are multiplexed with pre-generated view masks. All the processes are performed on a graphics processor. We were still able to play a 2D/True3D mixed contents with Full HD resolution in real-time using a normal graphics processor.
-
Over 5lm/W white luminous efficacy was obtained by 11" color test panel with narrowed discharge electrodes combined with high Xe partial pressure. By using optical spectroscopic methods, it was suggested that the electron heating efficiency is the most significant to improve the plasma efficiency in our experimental conditions.
-
We investigated experimentally the influence of the generation efficiency for excited Xe atoms on ultra-fine horizontal cell pitch AC PDPs. In the case of a 0.1 mm cell pitch, the sustain voltage increased; however, the generation efficiency was equal to or higher than for the conventional 0.22 mm cell pitch.
-
In this study, in order to improve luminous efficacy of AC-PDP, the new facing discharge structure has been suggested. The suggested structure has tilted facing electrode. It shows lower discharge current, higher luminance and luminous efficacy compared with those of reference structure with coplanar electrode structure.
-
A new electrode structure is proposed in this paper which can increase the discharge efficiency of plasma display panels and also decrease the panel capacitance by decreasing the electrode area effectively. Even with the decreased electrode area, the proposed structure could suppress the requirement for increasing the voltage and improve efficiency by limiting the discharge current.
-
Flexible electronics devices such as plastic display, thin film battery, membrane switch, organic memory for smart card applications will be presented. The performance and power consumption of various display technologies will be compared for OTP requirement in smart cards. Wireless power transmission by RF coupling through an antenna provides a potential power solution to smart cards. Finally, the general trend of smart card future developments will be discussed.
-
We developed tight adhesion techniques of two plastic substrates to maintain cell gap stability for rugged flexible LCDs. By combining rigid spacers and several adhesion materials, we demonstrated mechanically very stable flexible LCDs against pressure and bending.
-
Kim, Han-Jun;Almanza-Workman, Marcia;Chaiken, Alison;Elder, Richard;Garcia, Bob;Jackson, Warren;Jeans, Albert;Kwon, Oh-Seung;Luo, Hao;Mei, Ping;Perlov, Craig;Taussig, Carl;Jeffrey, Frank;Beacom, Kelly;Braymen, Steve;Hauschildt, Jason;Larson, Don 82
We are working towards large-area arrays of thin film transistors on polymer substrates using roll-to-roll (R2R) processes exclusively. Self-aligned imprint lithography (SAIL) is an enabler to pattern and align submicron features on meter-scaled flexible substrates in the R2R environment. The progress, current status and remaining issues of this new fabrication technology are presented. -
Krishnamoorthy, Ahila;Spear, Richard;Gebrebrhan, Amanuel;Stifanos, Mehari;Yellowaga, Deborah;O'Rourke, Shawn;Loy, Doug;Dailey, Jeff;Marrs, Michael;Ageno, Scott 86
Organosiloxane based spin on planarizing dielectrics (PTS-E and PTS-R) were developed for application in flat panel displays as a replacement to conformal chemical vapor deposited SiNx. Here we demonstrate the successful use of siloxane-based material as a passivation layer for active matrix$\alpha$ -Si thin film transistors (TFT) on both rigid and flexible substrates. -
The organic field-effect transistors with step-edge structure were fabricated. Source and drain electrodes were obliquely deposited by vacuum evaporation. The step-edge of the gate electrode serve as a shadow mask, and the short channel is formed at the step-edge. The excellent device performances were obtained.
-
We have fabricated wet-processed thin-film transistors of unsubstituted pentacene by two kinds of fabrications both solution and dispersion processes. Transistor performances with thin film structures including grain structures in the films by two pro cesses are studied.
-
Park, Jong-Won;Chung, Dae-Sung;Park, Jong-Hwa;Kim, Yun-Hi;Shim, Hong-Ku;Park, Chan-Eon;Kwon, Soon-Ki 98
A series of new channel materials using triisopropylsilylethynyl anthracene(TIPSAN) derivatives are synthesized by well known reaction. The TIPSAN derivatives exhibit an excellent field-effect mobility with hole mobility as high as 0.1 cm2V-1s-1 by solution-process and slip stack structure of core and end groups with short$\pi-\pi$ stacking distance of$3.525{\sim}3.485\;{\AA}$ by single crystal structures. -
Too high stress of the bottom Mo layer of the gate line is thought to be the main reason for H-line mura. H-Line mura is eliminated effectively by changing the gate line metal structure from Mo/AlNd/Mo to AlNd/Mo. The new structure does not influence the panel's electrical characteristics.
-
Cabarrocas, Pere Roca I;Abramov, Alexey;Pham, Nans;Djeridane, Yassine;Moustapha, Oumkelthoum;Bonnassieux, Yvan;Girotra, Kunal;Chen, Hong;Park, Seung-Kyu;Park, Kyong-Tae;Huh, Jong-Moo;Choi, Joon-Hoo;Kim, Chi-Woo;Lee, Jin-Seok;Souk, Jun-H. 107
The spectacular development of AMLCDs, been made possible by a-Si:H technology, still faces two major drawbacks due to the intrinsic structure of a-Si:H, namely a low mobility and most important a shift of the transfer characteristics of the TFTs when submitted to bias stress. This has lead to strong research in the crystallization of a-Si:H films by laser and furnace annealing to produce polycrystalline silicon TFTs. While these devices show improved mobility and stability, they suffer from uniformity over large areas and increased cost. In the last decade we have focused on microcrystalline silicon (${\mu}c$ -Si:H) for bottom gate TFTs, which can hopefully meet all the requirements for mass production of large area AMOLED displays [1,2]. In this presentation we will focus on the transfer of a deposition process based on the use of$SiF_4$ -Ar-$H_2$ mixtures from a small area research laboratory reactor into an industrial gen 1 AKT reactor. We will first discuss on the optimization of the process conditions leading to fully crystallized films without any amorphous incubation layer, suitable for bottom gate TFTS, as well as on the use of plasma diagnostics to increase the deposition rate up to 0.5 nm/s [3]. The use of silicon nanocrystals appears as an elegant way to circumvent the opposite requirements of a high deposition rate and a fully crystallized interface [4]. The optimized process conditions are transferred to large area substrates in an industrial environment, on which some process adjustment was required to reproduce the material properties achieved in the laboratory scale reactor. For optimized process conditions, the homogeneity of the optical and electronic properties of the${\mu}c$ -Si:H films deposited on$300{\times}400\;mm$ substrates was checked by a set of complementary techniques. Spectroscopic ellipsometry, Raman spectroscopy, dark conductivity, time resolved microwave conductivity and hydrogen evolution measurements allowed demonstrating an excellent homogeneity in the structure and transport properties of the films. On the basis of these results, optimized process conditions were applied to TFTs, for which both bottom gate and top gate structures were studied aiming to achieve characteristics suitable for driving AMOLED displays. Results on the homogeneity of the TFT characteristics over the large area substrates and stability will be presented, as well as their application as a backplane for an AMOLED display. -
Hong, Won-Eui;Lee, Joo-Yeol;Park, Doo-Jung;Ro, Jae-Sang;Ahn, Ji-Su;Lee, Il-Jeong;Kim, Sung-Chul 109
The grain size of JIC poly-Si can be varied from few tens of nanometers to the one having the larger grain size exceeding that of excimer laser crystallized (ELC) poly-Si according transmission electron microscopy. JIC poly-Si exhibits an excellent uniformity with regards to the grain size. We report here the blanket crystallization of the large area using the$2^{nd}$ generation glass substrate. -
Kang, H.S.;Kang, H.C.;Lee, M.H.;Park, S.Y.;Kim, M.J.;Heo, J.S.;Kim, D.W.;Noh, Y.H.;Lee, S.;Kim, J.Y.;Kim, C.D.;Kang, I.B. 113
The active layer thickness and curing condition dependent performance of an organic thin film transistor (OTFT) with inkjetted organic semiconductor (OSC) layer is studied The best performance of the OTFT was found when the thickness of ose was ~120 nm cured at$60^{\circ}C$ . The performance enhancement of the OTFT with inkjetted OSC layer was discussed by comparing the OTFT with spin-coated ose layer. -
In this paper, we describe the current status and issues of the oxide thin-film transistors (OTFTs), which attract much attention as an emerging new backplane technology replacing conventional silicon-based TFTs technologies. First, the unique benefits of OTFTs will be presented as a backplane for large-sized AMOLED including note-book PC, second TV and HD-TV. And then, the state-of-the-art transistor performance and uniformity characteristics of OTFTs will be highlighted. The obtained a-IGZO TFTs exhibited the field-effect mobility of
$18\;cm^2/Vs$ , threshold voltage of 1.8 V, on/off ratio of$10^9$ , and subthreshold gate swing of 0.28 V/decade. In addition, the world largest-sized 12.1-inch WXGA active-matrix organic light emitting diode (AMOLED) display is demonstrated using indium-gallium-zinc oxide (IGZO) TFTs. -
Han, Chang-Wook;Kim, Woo-Chan;Kim, Seung-Tae;Tak, Yoon-Heung;Ahn, Byung-Chul;Kang, In-Byeong;Chung, In-Jae 123
We report the improved AMOLED with a-Si TFT backplane based on our unique structure. Our new structure is called Dual-plate OLED Display (DOD). It can also achieve not only higher uniformity of luminance in large-sized display due to low electrical resistance of common electrode but also wider viewing angle. -
Bae, Han-Jin;Kim, Seung-Tae;Lim, Ho-Min;Ha, Won-Kyu;Lee, Jae-Do;Kim, Ji-Hun;Kim, Hak-Su;Han, Chang-Wook;Tak, Yoon-Heung;Ahn, Byung-Chul 127
A 2.2" QVGA($320{\times}240$ ) 262,114 color AMOLED module has been developed using digital driving methodology. In this paper, we discuss the development of diver IC which is applied to Digital AMOLED module. Technologies for low cost IC structure and image quality enhancement are presented. -
Since the invention of 'the Stereoscope' in 1838, many kinds of 3D display systems have been developed and used for various applications. In fact they have been at least proposed for virtually every application that uses 2D displays. In this paper, we introduce the various 3D display techniques and its products.
-
Developing from stereoscopic to autostereoscopic, researchers on display technology are trying to provide more depth cues to viewer, leading to the advent of true 3D display. Volumetric 3D displays seem to be practical technology at present. Ultimate display will function like human vision system, with characteristics of providing all depth cues and free interaction.
-
Local Dimming Technique for High Dynamic Range LCD by White LED Backlight with New Control AlgorithmDynamic range of LCD panel can be dramatically improved by adaptive dimming technique. Adaptive control of LED backlight by input signal can reduce the light leakage of LCD panel and achieve high contrast ratio. An algorithm is proposed to distinguish the input signal and get proper luminance level. For lower cost of LCD panel, white light LED is used to accomplish 2D dimming and get better image performance of LCD.
-
We have developed a 3.1-inch diagonal 2D/3D LCD with a novel pixel arrangement, called HDDP (Horizontally Double-Density Pixels), for high-quality 3D images. We have improved 3D visibility by broadening the 3D viewing zone where high-quality images can be seen, and we propose optical characterization methods which can evaluate the high-visibility autostereoscopic displays correctly.
-
The use of high Xe content gas is a powerful method for improving the discharge efficacy in PDP, but the accompanying high driving voltage prevents it from being used aggressively. In this paper, we tried to find a method to lower the driving voltage under high Xe gas condition with a new protecting layer. The effective secondary electron emission caused by Xe ions can result in the low voltage driving in panels with high Xe content gas and more importantly high luminous efficacy which were confirmed with the computer simulation and panel experiment.
-
Improved properties of second electron emission was evaluated by assemble of 4 inch PDP panel. MgO protection layers were deposited and examined by using both pellets made of extremely pure MgO single crystals and sintered pellets using MgO nano powders.
$\gamma$ coefficients higher than 0.11 were obtained from the panel by adopting dopant-controlled MgO single crystals. Especially the MgO layer deposited by sintered pellets made of nano powders showed the higher$\gamma$ coefficients at the operating voltage above 200 volts. -
We proposed 2-phase regression of power function inside exponential for PDP lifetime data analysis. In introducing our method we discussed the reason why PDP degradation behavior is described by exponential function basically. By applying our method to 50HD and 50FHD PDP lifetime experiment data, we obtained more than 100,000Hr lifetime. From these results, we claim that PDP lifetime is more than 100,000Hr.
-
Khan, Asad;Davis, Donald J.;Ernst, Todd;Marhefka, Duane;Miller, Nick;Montbach, Erica;Pishnyak, Oleg;Schneider, Tod;Doane, J.W. 167
$Reflex^{TM}$ display technology based on bistable, reflective, and flexible Cholesteric Liquid Crystal Displays is being developed and mass produced for new and non-traditional applications. These applications allow for personalization of mobile devices, very low cost display systems, and more. This display technology, its status, and new applications are discussed in this paper. -
Hack, Mike;Ma, Rui-Qing;Rajan, Kamala;Brown, Julie J.;Cheon, Jun-Hyuk;Kim, Se-Hwan;Kang, Moon-Hyo;Lee, Won-Gyu;Jang, Jin 171
We present results demonstrating that low power consumption phosphorescent AMOLED displays can be fabricated on ultra-thin ($25{\mu}m$ ) stainless steel substrates, combining an amorphous silicon backplane with a top emission phosphorescent OLED frontplane. We will present preliminary results of flexibility testing on these displays. -
Chen, Heng-Yin;Lu, Shao-Chuan;Chen, Shang-Chia;Lin, Hsuan-Kai;Liu, Sung-Ho;Chen, Chun-Ming;Liang, Chao-Chiun 175
A new laser-addressing method is proposed in this paper. With the characteristic of high power and small spot size, simple structure electronic paper can be addressed only by laser source, and high quality image with 300dpi resolution can be easily achieved. -
Major display equipment suppliers introduced equipment using inkjets for manufacturing steps such as printing polyimide alignment layers and color filters. This paper discusses how inkjets can be used in the development of flexible displays and materials printing systems designed to meet the challenges of fluids and process development.
-
We have analyzed the structures of
$Alq_3$ in different polymorphs by solid-state NMR. On the basis of the results, OLEDs were fabricated from different polymorphs of$Alq_3$ . The current efficiency of the device fabricated from the mixture of$\alpha$ -,$\gamma$ -, and$\delta-Alq_3$ powders was higher than that from$\alpha-Alq_3$ . -
Nakajima, Yoshiki;Takei, Tatsuya;Tsuzuki, Toshimitsu;Suzuki, Mitsunori;Fukagawa, Hirohiko;Fujisaki, Yoshihide;Yamamoto, Toshihiro;Kikuchi, Hiroshi;Tokito, Shizuo 189
A 5.8-inch wide-QQVGA flexible full-color active-matrix OLED display was fabricated on a plastic substrate. Low-voltage-operation organic TFTs and high-efficiency phosphorescent OLEDs were used as the backplane and emissive pixels, respectively. The fabricated display clearly showed color moving images when the driving voltage was below 15 V. -
$Orgacon^{TM}$ products, based on the conducting polymer PEDOT/PSS, are very promising materials in cost-effective R2R production of large area electronics. This presentation will show both the progress in the surface resistance/VLT and progress in the stability (T/R.H. and light stability). A new generation of films, coating formulations and inks will be presented. -
We propose a novel n-type a-Si:H TFT pixel circuit which is proper to AMOLED display for the large size and high resolution. Proposed pixel circuit will be suit to panel for the high resolution because of different threshold sampling method. Driving method of proposed pixel circuit is very simple like an AMLCD. Our simulation indicates that the proposed pixel circuit can compensate the Vth shift and IR rising of power line so that provide better quality image.
-
Based on the device physics, a new I-V equation for TFTs is derived and a simple parameter extraction method is suggested. The new method gives more physically meaningful threshold voltage and mobility, and the obtained values can be directly used for the TFT device modeling.
-
Cho, Sung-Haeng;Choi, Yong-Mo;Jeong, Yu-Gwang;Kim, Hyung-Jun;Yang, Sung-Hoon;Song, Jun-Ho;Jeong, Chang-Oh;Kim, Shi-Yul 205
The new process for hybrid silicon thin film transistor (TFT) using DPSS laser has been developed for realizing both low-temperature poly-Si (LTPS) TFT and a-Si:H TFT on the same substrate as a backplane of active matrix liquid crystal display. LTPS TFTs are integrated on the peripheral area of the panel for gate driver integrated circuit and a-Si:H TFTs are used as a switching device for pixel in the active area. The technology has been developed based on the current a-Si:H TFT fabrication process without introducing ion-doping and activation process and the field effect mobility of$4{\sim}5\;cm^2/V{\cdot}s$ and$0.5\;cm^2/V{\cdot}s$ for each TFT was obtained. The low power consumption, high reliability, and low photosensitivity are realized compared with amorphous silicon gate driver circuit and are demonstrated on the 14.1 inch WXGA+ ($1440{\times}900$ ) LCD Panel. -
Shin, Kyoung-Ju;Song, Se-Young;Lee, Il-Pyung;Kim, Chang-Hoon;Jang, Chang-Soon;Chai, Chong-Chul;Souk, Jun-Hyung 208
We have developed a LCD Panel that form storage capacitance for pixels between pixel electrode of bottom glass and common electrode of top glass. This method could make higher transmission and higher production yield than before by removing storage electrode line and capacitance on the bottom glass by simplifying bottom pixel structure. -
The TFTs from ZnO semiconductor with hafnium oxide dielectrics were prepared by atomic layer deposition to characterize the electrical properties. Good electrical properties of oxide TFT was obtained with channel mobility of
$2.1\;cm^2/Vs$ , threshold voltage of 0 V, the subthreshold slope of 0.9 V/dec, and on to off current ratio of$10^6$ . -
Kim, Woo-Jun;Cho, Joo-Woan;Yeo, Dong-Min;Ye, Byoung-Dae;Seo, Dong-Jin;Choi, Jin-Sung;Jang, Tae-Seok 214
We present an ultra-slim LCD module for 40-inch FHD TV. By employing edge-lit backlight system, module thickness of 10mm is achieved. To satisfy the luminance spec of 450 nits in FHD resolution, it is critical to adopt high efficient LED and optical components. -
Bottom-gate microcrystalline silicon thin film transistors (
${\mu}c$ -Si:H TFTs) were fabricated on glass and transparent polyimide substrates by conventional 13.56 MHz RF plasma enhanced chemical vapor deposition at$200^{\circ}C$ . The deposition rate of the${\mu}c$ -Si:H film is 24 nm/min and the amorphous incubation layer near the${\mu}c$ -Si:H/silicon nitride interface is unobvious. The threshold voltage of${\mu}c$ -Si:H TFTs can be improved by$H_2$ or$NH_3$ plasma pretreatment silicon nitride film. -
Yoon, S.M.;Cheong, W.S.;Hwang, C.S.;Kopark, S.H.;Cho, D.H.;Shin, J.H.;Ryu, M.;Byun, C.W.;Yang, S.;Lee, J.I.;Chung, S.M.;Chu, H.Y.;Cho, K.I. 222
We proposed the dry etching process recipe for the fabrication of In-Ga-Zn-O (IGZO)-based oxide TFTs, in which the etching behaviors of IGZO films were systematically investigated when the etching gas mixtures and their mixing ratios were varied. Good device characteristics of the fabricated TFT were successfully confirmed. -
Yan, Jing-Yi;Liao, Ko-Pin;Liao, Jin-Long;Chen, Liang-Hsiang;Lin, Mei-Ru;Lee, Tzu-Wei;Yeh, Shu-Tung;Cheng, Kung-You;Wu, Yen-Yu;Yu, Chien-Hsien;Lee, Yen-Ying;Ho, Jia-Chong 226
Pentacene based TFT showed a degraded mobility and saturation current (Ion) after exposure to the high energy ultraviolet (UV). In this article, we optimize the thickness of UV resisted layer on OTFT to restrain the degradation from protect layer deposition and study the UV aging effect of pentacene based TFT. The OTFT deivce with UV resisted layer could keep over 50% mobility after suffered UV$10^3J$ . -
Kim, Mi-Soon;Huh, Su-Jung;Suh, Duck-Jong;Ahn, Yi-Joon;Lee, Kyung-Jin;Ahn, Seon-Hong;Kim, Kyeong-Hyeon;Kim, Sang-Soo 228
The response time characteristic of low voltage liquid crystals (LCs) is investigated and a new simulator for low voltage LCs is proposed. In order to enable low voltage operation, it is important to minimize Vth of LCs and variation of pixel voltage caused by dynamic capacitance operation of LC Display. Because dynamic capacitance variation is much larger for low voltage LC operation compared to that of conventional LC material, it is necessary to make a better model for dynamic capacitance operation. A proposed minimizing Vth of LCs and variation of pixel voltage study results through a new constant charge model improve response characteristics for low voltage LCs operation. -
In this paper, we propose a novel electrode structure for superb transmittance in super in-plane switching (S-IPS) mode while keeping the features of the conventional SIPS mode such as the capability of initial LC alignment. The optimization of the electrode made it possible to enhance the light transmittance approximately by 14 % in comparison to the conventional S-IPS cell.
-
We report the improvement in brightness through the optimization of the organic passivation process for fabricating a TFT substrate for LCD-TV panel. In conclusion, the optimization of organic passivation was accomplished with improving over
$10\;cd/m^2$ in brightness than that of a conventional organic passivation process. -
We have investigated the reliability of short channel (
$L=1.5{\mu}m$ ) p-type ELA poly-Si TFTs under hot carrier stress. Threshold voltage of short channel TFT was significantly more shifted to positive direction than that of long channel TFT under the same stress. This result may be attributed to electron trapping at the interface between poly-Si film and gate oxide layer. -
Roll-printed organic thin-film transistors (OTFTs) were fabricated by gravure or flexography printing using patterned PDMS stamp with various channel lengths, silver pastes, coated polyvinylphenol dielectric, and jetted bis(triisopropyl-silylethynyl) pentacene semiconductor on plastic substrates. The roll-printed OTFT parameters were obtained: fieldeffect mobility of
$0.1\;cm^2/Vs$ , an on/off current ratio of$10^4$ and a subthreshold slope of 2.53 V/decade. -
Kim, Sung-Hwan;Kim, Sang-Soo;Park, Yong-In;Peak, Seung-Han;Lee, Kyoung-Mook;Park, Choon-Ho;Lim, Yu-Sok;Kim, Chang-Dong;Kang, In-Byeong 247
Low Temperature a-Si:H TFT on stainless steel substrate has been developed for the flexible electrophoretic display. Stability of low temperature a-Si:H TFT is more important point than its initial device characteristics. Thus, we have studied device characteristics of low temperature a-Si:H TFT in terms of stability for driving electrophoretic display. -
You, Bong-Hyun;Lee, Byoung-Jun;Lee, Ki-Chan;Han, Sang-Youn;Koh, Jai-Hyun;Takahashi, Seiki;Berkeley, Brian H.;Kim, Nam-Deog;Kim, Sang-Soo 250
A touch screen panel embedded 12.1-inch TFT LCD employing a standard a-Si:H TFT process has been successfully developed. Compared with conventional external touch screen panels, the new internal TSP exhibits a clearer image and improved touch feeling. Our new internal proposed TSP can be fabricated with low cost. -
We have investigated the effect of source/drain electrode deposition method on a performance of top gate structured ZnO TFT performance. TFT using S/D of ITO film, consisted of bi-layer which deposited by ion beam assisted sputtering at the initial stage then deposited by DC magnetron sputtering, showed better performance compared to that using S/D of ITO deposited by just DC magnetron sputtering. Two ITO films exhibited different grain shapes and these resulted in different etching properties. We also suspect that charge trapping on the glass substrate (back channel) during the ITO film deposition may influence the characteristics of top gate structured ZnO TFT.
-
Cheon, Ki-Cheol;Woo, Ju-Hyun;Jung, Deuk-Soo;Park, Mun-Gi;Kim, Hwan;Lim, Byoung-Ho;Yu, Sang-Jean 258
Developed halftone exposure technique was successfully applied to the fabrication of narrow transistor channels below$4\;{\mu}m$ with conventional photolithography method. Asymmetric slits concept of photo mask was applied to make channel lengths (L) shorter for thin film transistor's (TFT) high performance. These short channel TFTs verified better quality transistor characteristics. -
We attempted modulation of the hydrogen dilution ratio in a Cat-CVD system to achieve both the minimal incubation layer and the high throughput. We obtained the incubation layer thickness of 3 nm, and were able to grow a 200 nm-thick film having a 70 % crystallinity in 18 minutes.
-
Through-doping conditions with higher energies and doses were intentionally chosen to understand reverse annealing behavior. We observed that the implantation condition plays a critical role on dopant activation. We found a certain implantation condition with which the sheet resistance is not changed at all upon activation annealing.
-
We have examined the effect of physical drying and annealing conditions for the soluble derivatives of polythiophene as p-type channel materials of organic thin film transistors (OTFTs) in our special designed drying system; performances of the jetting-processed OTFTs can be improved more than 10 times just by optimizing the physical conditions of drying and annealing.
-
The contact resistance between organic semiconductor and source-drain electrode in Bottom Contact Organic Thin-Film Transistors (BCOTFTs) can be effectively reduced by metal oxide/molybdenum double layer structure; metal oxide layers including nickel oxide (NiOx/Mo) and moly oxide(MoOx) under molybdenum work as a high performance carrier injection layer. Step profiles of source-drain electrode can be easily achieved by simultaneous etching of the double layers using the difference etching rate between metal oxides and metal layers.
-
In this paper, we propose a novel electrode structure for In Plane Switching (IPS) mode LC cell which provides the enhanced transmittance and wider viewing angle as well as less color shift. The simulation results revealed that transmission increases by more than 11.9% and shows less color shift than the conventional S-IPS mode.
-
Air stable n-type organic field effect transistors (OFETs) based on CB60B are realized using a perfluoropolymer as the gate dielectric layer. The devices showed the field-effect mobility of
$0.05\;cm^2P/V\;s$ in ambient air. Replacing the gate dielectric material by$SiO_2$ resulted in no transistor action in ambient air. Perfluorinated gate dielectric layer reduces interface traps significantly for the n-type semiconductor even in ambient air. -
Lee, Chang-Soo;Lee, Min-Cheol;Lee, Yong-Soon;Bae, Yu-Han;Kim, Young-Su;Moon, Seung-Hwan;Kim, Nam-Deog;Kim, Sang-Soo 280
LCD-TV applications were successfully implemented using integrated gate drivers. Integrated gate drivers have been implemented on a HD panel for 60Hz operation and on a FHD panel for 120Hz operation. It is found that the integrated gate driver reduces the flicker of a panel. -
In this paper, a new Twisted Nematic (TN) transflective liquid crystal display configuration with single cell gap for both transmissive and reflective mode and without sub-pixel separation is proposed. The Transmittance vs. Voltage Curve (TVC) and Reflectance vs. Voltage Curve (RVC) are matched.
-
Kim, Su-Jeong;Kim, Kwang-Hyun;Jung, Ji-Yoon;Heo, Jeong-Uk;Lee, Nam-Seok;Kim, Kyeong-Hyeon;Kim, Sang-Soo 288
This paper describes a new S-PVA cell structure which achieves enhanced contrast ratio by adopting a step-like patterned common electrode between the high sub-pixel and low sub-pixel electrodes without loss of transmittance. A 24-inch panel was developed for monitor applications and measured contrast ratio and white luminance were over 2500:1 and 400cd/m2, respectively. -
We have developed new reflective LCD for Mixed twist nematic LC mode with high quality image. We have found out an optimal twist angle of LC and optical film's axis by simulation. Also we measured electro-optic characteristics for new design panel. As a result, high reflectance and wide viewing angle characteristics were achieved.
-
Kim, Jae-Hyun;Kim, Gee-Bum;Choi, Ji-Youn;Jang, Yong-Kyu;Ahn, Seon-Hong;Kim, Kyeong-Hyeon;Kim, Sang-Soo 295
We developed a novel PVA pixel design for mobile application with excellent off-axis image quality and optical performance by introducing Active Level Shift technology and optimizing pixel structure. Our new pixel design enables better off-axis image quality without sacrificing other optical properties compared with a conventional mPVA structure. -
We suggest a new method to evaluate the anti-smudge performance of LCD panels. The anti-smudge performance is characterized by oleic acid contact angle. This method shows accurate and reproducible result and overcomes the difficulty of quantitative evaluation for the anti-smudge characteristic and low reliability in several proposed measurements.
-
We present a new touch screen method, which utilizes the variation of liquid crystal capacitance according to the touch event on the screen. It is integrated in the AMLCD with the conventional LTPS process. Its resolution is same as the display resolution as well as performs the multi-touch sensing function basically. The design concept and the operation are verified with the SPICE simulation.
-
We proposed azimuthally continuous nematic domain mode characterized by a cone field induced from patterned electrode structure with a circular slit. This mode has good optical performances such as higher transmittance and wider viewing angle through decreasing the demerits caused by domain walls. We could confirm to these optical characteristics by the manufactured sample.
-
Recently, study on the weak interaction energy between the soft polymer surface and liquid crystals has been a primary topic for new LC device applications. In this paper, to understand the switching property of nematic liquid crystals (LCs) at the interface with a weak anchoring boundary, we investigate experimentally the rotation property of surface nematic director by electric field on non-treated Poly-Methylmethacrylate (PMMA,
$T_g=110^{\circ}C$ , Sigma Aldrich) film observed under various temperatures including the glass transition temperature ($T_g$ ) of the polymer layer. -
We examine the surface alignment of liquid crystals (LC's) by a double linearly polarized ultraviolet (LPUV) light expose process. Exposing polarized light induces a surface anisotropy to polyimide (PI) layer surfaces and hence determines the alignment direction. LPUV exposes with angular difference of
$45^{\circ}$ between two polarization directions make LC director change. -
Photo-alignment layer which contains cinnamate is difficult to generate pretilt angle of liquid crystals. In order to enhance pretilt angle, blending poly (amic acid) between containing fluorine poly (amic acid) and 1,2,3,4-cyclobutanetetracaroxylic dianhydride (CBDA) / 3,5-diaminobenzyl alcohol (DBA) were used. For photoreaction, cinnamate was conjugated by interfacial reaction with blending polyimide.
-
Jo, Eun-Mi;Srivastava, Anoop Kumar;Kim, Mi-Young;Kim, Sung-Min;Lee, Seung-Hee;Ji, Seung-Hoon;Lee, Gi-Dong 320
In this paper, electro-optical characteristic of Nematic Liquid crystal (LC) with varying temperature in different LCD modes, namely Fringe Field Switching (FFS), In-plane switching (IPS), and Patterned Vertical Alignment (PVA) modes are investigated and compared. Electro optic me asurements suggest that rate of change of transmission with temperature in FFS mode was lowest and much more thermally stable as compared to IPS and PVA m odes. However the electro-optical characteristic of patterned vertical alignment (PVA) mode was most affected by changing temperature. The measured threshold voltage was found to be much more thermally stable in FFS and IPS modes than that of PVA mode. -
Novel X-shaped molecules containing perfluoroalkyl alkanes as a side chain have been synthesized and characterized. The properties of mesophases were investigated by a combination of differential scanning calorimetry (DSC), polarizing optical microscopy (POM), X-ray diffractometry (XRD) and electro-optical measurements.
-
We have studied the optically compensated splay (OCS) mode using reactive mesogen monomer to reduce critical voltage, setting voltage and phase transition time from initial bend to splay state. The high pretilt angle from vertical alignment was formed through the polymerization of UV curable RM monomer at the surfaces. In this way, orientation of the LC with OCS can be achieved without setting voltage.
-
Banana-shaped molecules were synthesized introducing ester linking group into mesogenic unit, varying the central unit with 1,6-, 2,3-naphthylenes, and introducing the hexyloxy group as the terminal flexible unit. The properties of the compounds were characterized by FT-IR, NMR spectroscopy, DSC, polarizing optical microscopy, and X-ray diffractometry.
-
Kwon, Jang-Un;Lee, Su-Woong;Jung, Il-Ki;Han, Hwa-Dong;Park, In-Chul;Lee, Kyung-Ha;Moon, Hong-Man;Shin, Hyun-Ho 333
We have studied on optical properties of advanced S-IPS with a fine pitch electrode and a new finger design. Transmittance of panel increases with decreasing of width and angle of finger electrode. In order to improve transmittance, fine pitch electrode of${\sim}2{\mu}m$ and rubbing angle of 10 degree have been adopted. Various optical performances are defined as the function of finger design and field intensify across the IPS pixel electrodes. We have developed the advanced electrode structures with a high performance. As a result, the optical properties of 42" full HD with 120Hz frequency shows high transmittance over 5%, contrast ratio of 1800:1, gray-to-gray response time of 4.4ms, respectively. And also we have studied that the moving picture quality of IPS LCD is related with design parameters of IPS cells and finger shape. -
Recently, Note PCs have being widely used due to their features such as good mobility and low power consumption. In order to ensure the current market position, further improvement is required. Especially, the lower operating voltage is essential for the long operating time of Note PCs. For the achievement of lower operating voltage, possible contributions from LC materials side are to lower the viscosity and to increase the dielectric constant without sacrificing the reliability. In order to achieve lower driving voltage, new LC mixtures have been developed, optimizing theirs physical properties.
-
Kim, Mi-Young;Lim, Young-Jin;Jeong, Eun;Chin, Mi-Hyung;Kim, Jin-Ho;Srivastava, Anoop Kumar;Lee, Seung-Hee 340
This work reports the simple fabrication of the single cell gap transflective liquid crystal display (LCD) using wire grid polarizer. The nano sized wire grid polarizer was patterned on common electrode itself, on the reflective part of FFS (Fringe field switching) mode whereas the common electrode was unpatterned at transmissive part. However, this structure didn't show single gamma curve, so we further improved the device by patterning the common electrode at transmissive part. As a result, V-T curve of proposed structure shows single gamma curve. Such a device structure is free from in-cell retarder, compensation film and reflector and furthermore it is very thin and easy to fabricate. -
We fabricated the outer type-dynamic microlens array using a surface-stabilized ferroelectric liquid crystal, UV curable polymer and the stacked liquid crystalline polymer. The outer type-microlens array has a lower driving voltage and fast switching property. It is applicable to a variety of optical systems.
-
We suggest a viewing angle control mode of liquid crystal display(LCD) with additive thermal controllable optical layer [TCOL], which composed of homeotropically or homogenously well aligned LC layer and patterned hating lines on a substrate. In this system, LCD modes with wide viewing angle characteristics can be used as a main panel.
-
A 15.4" WXGA TFT-LCD, featuring integrated a-Si:H gate driver circuits and reduced data driver ICs, has been developed. To reduce number of data lines into 1/2 of conventional structure, the pixel array has been re-mapped with re-organized data signal. Unintended artificial effects such as flicker were removed by adopting the novel pixel array having a 'zigzag' map. To minimize the power consumption, a column inversion method was incorporated in the zigzag pixel array (Fig.1) without modifying the polarity map of conventional dot inversion method.
-
We report a method for improving characteristics of AC PDP in this study. This improvement is obtained by spreading MgO nanoparticles on transparent dielectric layer. These nanoparticles are covered with MgO protective layer by electron beam evaporation. MgO nanoparticle has difference in cathodoluminescence stronger than MgO layer by electron beam evaporation. This method worked for reducing statistical delay especially. Efficacy, discharge voltage and luminance were also improved But these improvements has limited lifetime because continuous ion bombardments changed characteristic of MgO surface.
-
Glasses in the
$SnO_2-(50-x)P_2O_5-xB_2O_3$ system were examined as potential replacement for the PbO glass frits with low firing temperature for component materials of a plasma display panel. The glasses were evaluated for their structural and the thermal expansion coefficient, glass transition and glass softening temperatures and Vickers hardness as a function of the$B_2O_3$ content. -
In this experiment, MgO thin films were deposited by oxygen neutral beam assisted deposition (NBAD) method. The results show that neutral beam energy plays an important role in the surface morphology, crystal orientation, defects of MgO thin films, and discharge characteristics of AC PDP.
-
The discharge characteristics of He-Ne-Xe gas mixture with the variation of Xe content are investigated through the numerical simulation. VUV efficacy in the gas condition of low Xe content increases due to more excitation and the case of high Xe content shows the improvement of VUV efficacy with the increase of He content but decreased VUV efficacy after tthe He mixing ratio of He and Ne is 0.5 due to frequent ionization.
-
Black matrix and Ag electrode with uniform line pitches were successfully fabricated through the photolithographic process by using the photosensitive black pastes and Ag pastes with optimized photosensitive properties for high resolution PDPs. The photosensitivity of the black and Ag pastes in the photolithographic process was investigated with the variation of photosensitive BM and Ag pastes and the photolithography process conditions. The important components and formulation of the photosensitive BM and Ag paste we discussed.
-
Lee, Heon-Seok;Hwang, Jong-Hee;Lim, Tae-Young;Kim, Yoon-Hee;Lee, Suk-Hwa;Kim, Il-Won;Lee, Jong-Koo 373
New glass compositions for lead free, low temperature sealing glass frit was examined in$ZnO-V_2O_5-P_2O_5$ glass system which can be used sealing material for PDP to be made of soda lime glass substrates. Among many glass compositions, KFS-C glass showed low glass transition point (Tg) and good fluidity and adhesion characteristics when it was tested by flow button method at low temperature of$420^{\circ}C$ . Its Tg was$317^{\circ}C$ and thermal expansion coefficient (CTE) was$70{\times}10^{-7}/K$ . The glass frit was mixed with an organic vehicle to make a paste and it was dispensed and sealed with soda lime glass substrates at$420^{\circ}C$ for 10min. Sealed glass panels also showed good adhesion strength even sealed at low temperature of$420^{\circ}C$ . -
In this work, we measured the spatiotemporal surface charge distribution by the longitudinal electro-optic amplitude modulation method with BSO single crystal to investigate the decay and diffusion characteristics of surface charges in three types of MgO. The speed of decay and diffusion of two different kinds doped MgO is compared with those of pure MgO. The difference in the characteristics of the decay and diffusion between the electron and ion surface charges is investigated separately. We found that the rate of ion decay is the major factor that makes the difference of the temporal variation of wall voltage among different types doped MgO.
-
One of important factors responsible for image sticking in AC PDP is a sputtering of MgO layer under ionic bombardment. Sputtered Mg particles can migrate to the neighbor cells, where the migration makes a change of discharge condition. It leads to the local non-uniformity of a luminescence in the panel, resulting in the image sticking.
-
We have studied the adsorption of contaminations on the MgO protective layer by Thermal Desorption Spectrometry (TDS). The result shows that the increase in exposure time, MgO thickness and humidity multiply the quantity of adsorbed contaminations. It is also found that the desorption activation energy and contamination quantity is decreased by the additional firing process of MgO layer under oxygen environment.
-
Eom, Cheol-Hwan;Lim, Hyun-Muk;Lee, Jun-Young;Kong, Byoung-Goo;Park, Hyun-Il;Moon, Sung-Hak;Kang, Jung-Won 388
A new reset waveform with negative ramp pulse was proposed. Comparative experiments between the negative and positive waveforms were performed. During reset period, IR distributions and luminance of black and white conditions were measured with the 42-inch XGA PDP module. The negative waveform improved contrast ratio about 15.4 ~ 22.5 % than the positive waveform by lowing the black luminance in reset period. Z bias (= Vbb) of the positive waveform was 27 V higher than the negative waveform. -
To improve the luminance in ac PDP, a new single sustain waveform with auxiliary address pulse is proposed. The new single sustain waveform was examined with 2 dimensional fluid codes and related experiments were performed with 42-inch XGA PDP module. At the same sustain level (= 180 V), the new waveform showed 3.6 times higher IR emission than the general waveform without auxiliary address pulse.
-
In this study, the electric field distributions have been investigated by simulation in accordance with the various shapes of ITO-electrodes. Also we have measured the density of excited Xe atoms in the 1s5 state in discharge cell, where the gap distance of 60 um, gas pressure of 400 Torr, Xe contents of 7%, and sustaining voltage of 200 V are kept in this experiment. The maximum density of excited Xe atoms in the 1s5 state in a discharge cell for the fish-boned, T shaped and squared ITO electrodes have been measured to be
$3.01\;{\times}\;10^{13}\;cm^{-3}$ ,$2.66\;{\times}\;10^{13}\;cm^{-3}$ and$2.06\;{\times}\;10^{13}\;cm^{-3}$ , respectively. It is shown that the electric field distribution with different ITO Electrodes is essential factor for these maximum density of excited Xe atoms in discharge cell. -
We have investigated the electro-optical characteristics of AC-PDP with different MgO protective layers, which have been deposited by electron beam evaporation from various sintered pellets with different temperatures. We have measured the secondary electron emission coefficient (
$\gamma$ ) by using the Gamma Focused Ion Beam ($\gamma$ -FIB) system, the static margin, and the address delay time. Also, we have investigated photoluminescence (PL) characteristics for understanding the energy levels of MgO pellets and protective layers. -
Song, In-Choel;Hwang, Seok-Won;Cho, Sung-Yong;Lee, Don-Kyu;Lee, Ho-June;Park, Jung-Hoo;Lee, Hae-June 404
Several ITO-less PDP cell structures are presented to improve luminous efficacy. The ITO-less PDP have been applied recently at actual panel manufacture. The influence of ITO-less PDP cell structure on the discharge characteristics has been investigated by using three-dimensional fluid simulation. The variations of electrode geometry parameters such as gap distance, cross bar length, and hump length are investigated for the optimization of cell design. -
In an attempt to enhance luminance efficiency and to reduce discharge delays of test panels with aluminum fence-electrodes, various designs of the electrodes were prepared by chemically etching the aluminum foils bonded to soda-lime glass substrate via anodic bonding process. The effects of fence design on luminance and discharge characteristics were investigated and compared with conventional ac-PDPs. These results showed a possibility of using fence-type aluminum electrode at front plates of ac-PDDs without sacrificing its performance.
-
Effects of Address Electrode Width on Address Discharge Under Variable Ambient Temperature in AC-PDPIt is known that the address discharge delay time during an address period strongly depends on the wall charge leakage. It was observed that the wall charge leakage during an address period is related to both the address width and the ambient temperature. Accordingly, the effects of address electrode width on the address discharge and wall voltage variation during an address period were examined under variable temperatures.
-
In this study, we report on the characteristics of Aldoped ZnO (AZO) co-sputtered indium tin oxide (ITO) films prepared by dual target direct current (DC) magnetron sputtering at room temperature for organic light emitting diodes (OLEDs). The electrical and optical properties of co-sputtered IAZTO electrode were critically dependent on the DC power of AZO. Furthermore, the characteristics of co-sputtered IAZTO electrode were influenced by rapid thermal annealing temperature.
-
The characteristics of
$Al_2O_3/Ag/Al_2O_3$ multilayer passivaton prepared by twin target sputtering (TTS) system for organic light emitting diodes. The$Al_2O_3/Ag/Al_2O_3$ multilayer thin film passivation on a PET substrate had a high transmittance of 86.44 % and low water vapor transmission rate (WVTR) of$0.011\;g/m^2$ -day due to the surface plasmon resonance (SPR) effect of Ag interlayer and effective multilayer structure for preventing the intrusion of water vapor. Using synchrotron x-ray scattering and field emission scanning electron microscope (FESEM) examinations, we investigated the growth behavior of Ag layer on the$Al_2O_3$ layer to explain the SPR effect of the Ag layer. This indicates that an$Al_2O_3/Ag/Al_2O_3$ multilayer passivation is a promising thin film passivation scheme for organic based flexible optoelectronics. -
We make performance simulations of three different organic light-emitting diodes (OLEDs), one of which is based on a conventional layered structure and the others on a blended structure where an emitting layer (EML) is either uniformly or stepwise mixed with an electron transport layer (ETL), Tris-(8-hydroxyquinoline) aluminum (
$Alq_3$ ). -
We demonstrated high power efficiency and long lifetime for organic light-emitting diode (OLED) using a new electron transport material (ETM-1). A power efficiency of the device with ETM-1 was improved compared to a standard device using tris(8-hydroxy-quinolinate)aluminum (
$Alq_3$ ). Moreover, the lifetime was 4 times longer than the standard device. -
The physical OLED analog behavioral model for SPICE simulation has been described using Verilog-A language. The model is based on the carrier-balance between the hole and electron injected through Schottky barrier at anode and cathode. The accuracy of this model was examined by comparing with the results from device simulation.
-
Lee, Kum-Hee;Kwon, Young-Soo;Kang, Lee-Kyung;Kim, Gu-Young;Seo, Ji-Hoon;Kim, Young-Kwan;Yoon, Seung-Soo 435
We demonstrated the efficient blue organic light-emitting diodes (OLEDs) by employing diarylamino-fluorene derived blue fluorescent molecules as dopants. Among those, a device exhibited blue emission with the luminous efficiency of 11.2 cd/A at$20\;mA/cm^2$ , the external quantum efficiency of 9.7% at$20\;mA/cm^2$ , and the$CIE_{x,y}$ coordinates of (x=0.163, y=0.259) at 8V. -
A mixed host structure of TCTA and TPBI was used in orange emitting layer and host composition was critical to device performances of PHWOLEDs. PHWOLEDs with TPBI host in orange emitting layer showed high quantum efficiency of 10.3 % at
$1000\;cd/m^2$ with little change of CIE coordinates of (0.32, 0.34) from$100\;cd/m^2$ to$10,000\;cd/m^2$ . -
We have fabricated vertical type organic thin film transistor using
$C_{60}$ as a n-type active material to improve the problems of conventional OTFTs. In general, it can be argued that the characteristics of organic transistor were influenced by carrier mobility and density. We have used several kinds of metals as source and gate electrodes to optimize the device characteristics using$C_{60}$ . In addition, we have examined the feasibility of fabrication of organic light-emitting transistor (OLET) using MEH-PPV as an emission layer. -
Organic light emitting diodes (OLEDs) with multiple organic layers were fabricated to obtain and to evaluate an equivalent resistance and an equivalent capacitance of OLED device. The staircase voltage with an increasing period and a constant period was designed and applied to the OLED. The resistance of OLED was found to decrease from
$270\;k{\Omega}$ to$2\;K{\Omega}$ as applied voltage increased after turn on. The equivalent capacitance of OLED maintained unchanged at low voltage level and deceased after showing peak value as the applied voltage increased. -
We synthesized a new HIL and HTL materials by using phenothiazinly moiety, 1,4-diphenothiazyl-benzene [DPtzB], 3',7',3",7"-tetrakis(N-phenyl-2-naphthylamine)-1,4-diphenothiazyl-benzene[PNA-DPtzB]. Synthesized materials exhibited high Tg in the range of
$175\;-\;202^{\circ}C$ . These values are much better than commonly used hole transporting materials (2-TNATA and NPB). The OLED device that used DPtzB as a HIL showed the highest efficiency of 4.31cd/A at$10mA/cm^2$ . -
Jung, Sung-Hyun;Lee, Ho-Jae;Kim, Young-Hoon;Kim, Hyung-Sun;Yu, Eun-Sun;Chae, Mi-Young;Chang, Tu-Won 454
We report the syntheses, photophysical properties and device performances of solution processible host material for green-phosphorescent OLEDs. The butterfly-shaped new host materials with nonconjugated linkage of carbazole and fluorene moieties have large triple energy band gap around 2.8 eV. All of the EL devices exhibited turn-on voltages in the range of 4.8-5.0 V. GH-4 exhibited the best performance with a maximum current efficiency and power efficiency of 21.1 cd/A and 7.9 lm/W. -
Four kinds of copolymers with fluorene and biphenylamine units were synthesized by palladium-catalyzed polycondensation reaction. These polymers were characterized in terms of their UV/Visible and photoluminescence (PL) properties in solution and film state. These polymers were also studied as a hole transporting material in the polymer light emitting diode (PLED) devices.
-
We have developed low voltage driving red phosphorescent organic light-emitting devices using a new electron transport layer.
$Ir(piq)_3$ and CBP were used as a phosphorescent dopant and an emission host, respectively. The device exhibits a luminance of$1000\;cd/m^2$ at a voltage of 2.8 V. This high luminance at low voltage results from a high electron conduction behavior of the new electron transport layer. -
New green light emitting phosphorescent devices with host structure of TCTA[4,4',4"-tris(N-carbazolyl)-triphenylamine]/
$TCTA_{0.5}TPBi_{0.5}$ /TPBI[1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene] were proposed and investigated according to the thickness combination of host layers and the doping level of$Ir(ppy)_3$ [tris(2-phenylpyridine) iridium(III)]. -
New iridium complexes with 2-(3',5'-bis-trifluoromethylphenyl)-4-metoxypyridine [
$(CF_3)_2ppyOMe$ ] were synthesized and characterized for blue phosphorescent materials. It was found that$Ir[(CF_3)_2ppyOMe]_2$ (acac) gives blue emission at 471 nm with strong luminescence efficiency. We discuss the role played by electron withdrawing substituents and also how the ancillary ligand influences the emission peak. -
A simple voltage compensation pixel circuit for AMOLED is produced using low temperature polycrystalline silicon (LTPS) technology. Its operation is verified by AIM-SPICE. Simulation results show that the pixel circuit has high immunity to variation of LTPS-TFT and reduces the drop in luminance due to the degradation of the OLED.
-
A highly efficient white phosphorescent OLED with a "tetra-chromatic" emission was fabricated by using an external color tuning layer (ECTL) which is composed of a layer of greenish yellow organic dye dispersed in PMMA on the outside of the glass. The ECTL combining with a lower red dopant concentration in the device has been found to improve the efficiency of a conventional WOLED by more than 27%.
-
In order to reduce IR drop through common electrode in AMOLED, we propose a novel method to form electrical contact between highly-conductive bus lines and common electrode by using a plasma-assisted patterning of OLED layers and double deposition of the common electrode. Plasma-assisted patterning effects on OLED performance and degradation have been investigated. This patterning method caused turn-on voltage decrease, current flow increase at the same applied OLED voltages, quantum efficiency decrease, and rapid degradation at early stage during the lifetime test. However, comparable 70% luminance lifetime were obtained for both patterned and non-patterned OLEDs.
-
By the oxygen plasma exposure to the organic light-emitting diodes, the turn-on voltage decreased from 10.5 to 7 V and luminance increased from 470 to
$852\;cd/m^2$ . Synchrotron radiation photoelectron spectroscopy results showed that during oxygen plasma exposure, oxygen ions were diffused into organic layer and induced p-type doping effect. -
The variations of the TFT characteristics in AMOLEDs result in the decrease of the uniformity of the displays. Measurement of the long-range uniformity (LRU) is straightforward. However, there is no method for measuring the short-range uniformity (SRU) yet. Quantifying the SRU is important in evaluating various TFT backplanes and compensation circuits. We propose new methods for measuring SRU.
-
Efficient top-emitting organic light-emitting diodes were fabricated using copper iodide (CuI) doped NPB as a p-doped hole injection layer to improve hole injection from a silver bottom electrode. The enhanced hole injection is originated from the formation of the charge transfer complex between CuI and NPB. The devices result in high efficiency of 69 cd/A with almost Lambertian emission pattern.
-
We have developed green phosphorescent organic light-emitting diodes (OLEDs) with high quantum efficiency. Wide-energy-gap material, 1,1-bis[(di-4-tolylamino) phenyl]cyclohexane (TAPC), with high triplet energy level was used as a hole transporting layer. Electrophosphorescent devices fabricated using TAPC as a hole-transporting layer and N,N'-dicarbazolyl-4,4'-biphenyl (CBP) doped with fac-tris(2-phenylpyridine) iridium [Ir(ppy)3] as the emitting layer showed the maximum external quantum efficiency (
$\eta_{ext}$ ) of 19.8 %, which is much higher than the devices adopting 4,4'-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (NPB) (${\eta}B_{ext}=14.6%$ ) as a hole transporting layer. -
Effects of dielectric capping layer in the phosphorescent top emitting organic light emitting diodesEffects of a dielectric capping layer on the luminous characteristics of top emitting organic light emitting diodes (TOLEDs) have been analyzed using a classical electromagnetic theory. Special attention was given to the influence of the cavity length on the effectiveness of the capping layer. The luminance characteristics of the TOLEDs influenced by the combined effects of the cavity length and the capping layer thickness. Furthermore, these combined effects also modify the emission spectrum and pattern of the TOLEDs, which result in the improvement of total luminance of the device, but no significant change in the device out-coupling efficiency.
-
Park, Hyung-Dol;Kang, Jae-Wook;Lee, Deug-Sang;Kim, Ji-Whan;Jeong, Won-Ik;Park, Young-Seo;Lee, Se-Hyung;Go, Kyung-Moon;Lee, Jong-Soon;Kim, Hyong-Jun;Kim, Jang-Joo 503
A host material containing tetraphenylsilane, 9-(4-triphenylsilanyl-(1,1'4,1")-terphenyl-4"-yl)-9H-cabazole (TSTC), was synthesized for green phosphorescent organic emitting diodes.$Ir(ppy)_3$ based OLEDs using TSTC host and DTBT (2,4-diphenyl-6-(4'yl)-1,3,5-triazine) hole blocking layer (HBL) showed the maximum external quantum efficiency of 19.8 %, the power efficiency of 59.4 lm and high operational stability with a half lifetime of 160,000 h at an initial luminance of$100\;cd/m^2$ . -
In this work, we used impedance spectroscopy analysis to determine the effect of the
$HfO_X$ treatment on the surface of ITO and to model the equivalent circuit for OLEDs. Devices with an ITO/Organic material/Al structure can be modeled as resistances and capacitances arranged in parallel or in series. The number of elements depends on the composition of the structure, essentially the number of layers, and the contacts. -
In this study, colorimetric characteristics of a 2.2-inch iriver MP4 based upon OLED was evaluated and compared with another MP4 based upon Liquid Crystal Display (LCD). According to IEC61966-4, the two displays were tested in terms of spectral power distribution, tone reproduction curve (TRC), luminance, contrast, correlated color temperature, 2D color gamut and spatial uniformity. Consequently, the OLED showed better performance for the first four aspects but a similar quality was observed for the rest.
-
Choo, D.C.;Bang, H.S.;Ahn, S.D.;Lee, K.S.;Seo, S.Y.;Yang, J.S.;Kim, T.W.;Seo, J.H.;Kim, Y.K. 513
The luminance efficiency of the red organic light-emitting devices fabricated utilizing a double electron transport layer (ETL) consisting of an Al-doped and an undoped layer was investigated. The Al atoms existing in the ETL acted as hole blocking sites, resulting in an increase in the luminance efficiency. -
A voltage-programming pixel circuit, which compensates the threshold voltage shift of TFTs and the degradation of OLED, is proposed for large sized a-Si:H active matrix organic light emitting diode (AMOLED) applications. Considering threshold voltage variation (or shift), OLED degradation and reverse bias annealing, HSPICE simulation results indicate that luminance error of every gray level is less than 0.4 LSB under the condition of +1V threshold voltage shift and from -0.2 LSB to 2.6 LSB within 30% degradation of OLED in the case of 40-inch full HDTV condition.
-
Jeon, So-Hee;Kang, Jae-Wook;Park, Hyung-Dol;Shim, Jong-Youp;Jeong, Jun-Ho;Kim, Se-Heon;Youn, Jae-R.;Kim, Jang-Joo 521
An etch-less simple method was developed to fabricate two-dimensional nanostructures on glass substrate directly by using UV curable polymer resin and UV nanoimprint lithography in order to improve output coupling efficiency of OLEDs. OLEDs integrated on nanoimprinted substrates enhanced electro-luminance intensity by up to 50% compared with the conventional device. -
Inkjet printing is being considered as an alternative to the conventional lithography in the electronic industry. Surface energy control of substrate is a critical issue in controlling the dimension of microstructures by the inkjet printing. This study introduces the surface energy control of ITO substrate for in/q'et printing of PEDOT/PSS.
-
By combining tetraphenylethylene and anthracene, we synthesized 9,10-bis(4-(1,2,2-triphenylvinyl)phenyl) anthracene [BTPPA] and 1,2-di(4'-tert-butylphenyl)-1,2-bis(4'-(anthracene-9-yl)phenyl)ethene [BPBAPE]; both BTPPA and BPBAPE have similar band-gaps, however their PL spectra were shifted by about 30 nm with respect to each other. The fabricated multilayered non-doped OLED devices based on pure BTPPA or BPBAPE exhibited luminance efficiencies of 3.93 cd/A at 6.8 V and 10.33 cd/A at 8.1 V, respectively, at
$10\;mA/cm^2$ . As the BPBAPE content of the emitting layer increased, the luminance efficiency of the device increased; in addition, the CIE coordinates of the fabricated devices shifted gradually from deep-blue for pure BTPPA to sky-blue for pure BPBAPE. -
Hwang, Soo-Woong;Lee, Soo-Hwan;Choi, Jae-Youn;Yoon, Hyun-Soo;Kim, You-Hyun;Chae, Soo-Joh;Kim, Woo-Young 530
Inorganic metal multi-layer(IMML) consisting of Al/Al:SiO/Al was developed as a cathode for OLED to reduce the reflectance generated from ambient light. Device structure of green OLED was ITO/2-TNATA/$\alpha$ -NPD/$Alq_3$ :C545T/Balq/$Alq_3$ /LiF/IMML and IMML was composed of three different layers: thin aluminum layer, aluminum layer doped with silicon monoxide and thick aluminum layer. Average reflectance of green OLED was 9.63% while that of conventional OLED with or without polarizer showed the average reflectance of 8.54% and 66% respectively at visible range from 380 nm to 780 nm. -
The anthracene derivatives were synthesized by Suzuki coupling reaction. The thermal, optical and electronic properties of MNAn and BIPAn were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry(DSC), UV-vis absorption, photoluminescen ce spectroscopies, and cyclic voltammetry. The materials exhibit high thermal stability and high per formance in EL devices.
-
WOLED devices were fabricated using two complementary color method with two emissive layers of blue and orange color respectively. WOLED's color purity was optimized as changing thickness of blue emissive DPVBi layer with most efficient red emissive layer doped with 0.2% DCJTB in
$Alq_3$ and obtained better white color coordinates of (0.36, 0.33) at 9V. -
By ETFOS software simulation to swiftly find out the shortcomings of the device structure and conserve the wastage of time cost in experiments, including the instruments deviations or human errors. Thereby we can calibrate the correct organic layer thickness by comparing the EL spectra with different NPB thicknesses.
-
In the fabrication of inverted top emission organic light emitting diodes (ITOLEDs), the organic layers are damaged by high-energy plasma sputtering process for transparent top anode. In this study, the plasma process induced damages on metal oxide hole injection layers (HILs) including
$WO_3$ ,$MoO_3$ , and$V_2O_5$ as buffer layer are examined. With the result of IV characteristic of hole-only devices, we propose that$MoO_3$ and$V_2O_5$ are stable materials against plasma sputtering process. -
We report the synthesis of blue emitting materials with a new core structure containing indenopyrazine. Non-doped device using one of these materials as a blue emitter was found to exhibit high external quantumn efficiency of 4.6% and excellent color purity of (0.154, 0.078) as well as narrow emission band of 47nm FWHM.
-
Kim, Young-Hoon;Yu, Eun-Sun;Kim, Nam-Soo;Jung, Sung-Hyun;Kim, Hyung-Sun;Lee, Ho-Jae;Kang, Eui-Su;Chae, Mi-Young;Chang, Tu-Won 549
We have developed a novel bipolar host material with both electron and hole transporting characteristics. Since CGH(Cheil Green Host) has some electron transporting characteristics, it shows increased luminance efficiency in device including TCTA and without HBL(hole blocking layer:BAlq). Maximum power efficency of CGH was 27.4lm/W at the device structure ITO/DNTPD(60)/NPB(20)/TCTA(10)/EML(30)/Alq3(20)/LIF(1)/Al. We measured device performance again without HBL. The result of CGH showing 26.0lm/W is outstanding compared to that of CBP showing 19.1lm/W without holeblocking layer. We also measured lifetime and found to be 205hr at 3000nit, that is significant result compared to the life time of CBP device showing 82hr. CGH shows high device performance with holeblocking layer. Moreover, it shows better device performance and life time than those of CBP without holeblocking. -
Parikh, Kunjal;Choi, Joon-Hoo;Cho, Kyu-Sik;Huh, Jong-Moo;Park, Kyong-Tae;Jeong, Byoung-Seong;Park, Yong-Hwan;Kim, Tae-Youn;Lee, Baek-Woon;Kim, Chi-Woo 553
We hereby report novel driving scheme to eliminate effect of "residual" image sticking (RRI) problem which arises due to hysteresis problem in Thin Film Transistor (TFT) in AMOLED Displays. The driving scheme applies "black" voltage after every data voltage period in order to drive AMOLED in uni-direction. The system can be easily implemented with 120 Hz driving scheme which is well matured in AMLCD industries. Our analyses show systematic evaluation of the problem and thereby solving it by simple methods which will be significantly effective of driving OLED towards mass manufacturing stage. -
The main goal of this work is to fabricate light emitting diode (LED) module and apply it to mobile handset. We first fabricated the blue-color LED based on the AlInGaN cell structure with size of
$200\;{\mu}m\;{\times}\;200\;{\mu}m$ . Also we proposed a new$1.0\;mm\;{\times}\;0.5\;mm$ (1005size) packaging procedure for the LED cell. Thus the overall dimension of our LED cell was as small as$1.0\;mm\;{\times}\;0.5\;mm\;{\times}\;0.4\;mm$ ($W\;{\times}\;L\;{\times}\;T$ ). As far as we knew it was the first time that this small LED cell dimension had been fabricated and operated. -
$Ba_{1-x}M_xGa_2S_4:Eu^{2+}$ (M = Ca, Sr) phosphor was prepared for white light emitting diodes application. Photoluminescence (PL) emission and excitation bands were red-shifted with increase of Ca and Sr content due to the crystal field effect. Moreover, the PL intensity under 450 nm was increased by substitution of Ca and Sr. -
In this study, a blue-emitting
$Sr_2MgSi_2O_7:Eu^{2+}$ (SMS) phosphor for white light-emitting diodes is reported. Through transition of$4f{\rightarrow}5d$ in$Eu^{2+}$ , SMS showed a strong blue emission under UV excitation. Additionally, the variation of emission wavelength of SMS is explained by crystal field effect and is supported by rietveld refinement. -
The structural and optical properties on
$Bi^{3+}$ addition in (Y,Gd)(V,P)$O_4:Eu^{3+}$ red phosphor were investigated. With the addition of$Bi^{3+}$ , the band edge in excitation spectrum shifts toward longer wavelength region, resulting in remarkable enhancement of the red emission intensity at 619 nm. -
Photo leakage characteristics of a-Si:H TFT were obtained for the illuminations from various backlight sources and the results were compared and analyzed in terms of the photoelectric properties of light. The analysis shows that the photocurrents are related to the wavelengths of the peak intensities of the spectrums of light sources.
-
Cho, Tae-Yeon;Park, Ja-Il;Han, Sang-Do;Gwak, Ji-Hye;Shin, Dong-Hyuk;Chun, Il-Su;Han, Chi-Hwan 576
ZnS:Cu,Cl blue-green phosphors were prepared by conventional solid state reaction. Copper activator of different concentrations was doped into ZnS structure at two firing steps. The luminescence characteristics dependent on$Cu^{2+}$ doping concentration of the phosphors has been investigated for inorganic electroluminescent device. -
Kwon, Byoung-Hwa;Vaidyanathan, Sivakumar;Li, Hui;Jang, Ho-Seoung;Yoo, Hyoung-Sun;Jeon, Duk-Young 578
Blue-emitting$CaAl_2Si_2O_8:Eu^{2+}(CAS:Eu^{2+})$ phosphor, prepared by solid-state reaction, is described in this paper. We researched the effect of boron ion substitution in the host materials. The phase and luminescent properties were investigated using the powder X-ray diffraction(XRD) and photoluminescence(PL) spectra. -
$BaMgP_2O_7$ :Eu,Mn phosphors for white emission were synthesized and their luminescent properties were investigated under UV excitation. The phosphor emits two colors: a blue band by$Eu^{2+}$ and a red band by$Mn^{2+}$ . Due to the efficient energy transfer from$Eu^{2+}$ to$Mn^{2+}$ , the red emission positioned at 615 nm is greatly enhanced with increasing$Mn^{2+}$ content up to 17.5 mol%. -
Depending on host environments,
$Eu^{2+}$ emission can be spectrally tuned by manipulating the energy levels between allowed$4f{\leftrightarrow}5d$ transition. Spectral variations of$Eu^{2+}$ emission from narrow green emission to broad yellow emission band were achieved by varying the host lattices such as Sr- or Ba-silicate, borate, and borosilicate. -
Yellow-emitting
$Y_3Al_5O_{12}$ :Ce nanocrystalline phosphor and orange-emitting CdS:Mn/ZnS core/shell quantum dots were prepared by a modified polyol and a reverse micelle chemistry, respectively. To compensate a poor color rendering index of YAG:Ce nanocrystalline phosphor due to the lack of red spectral component, CdS:Mn/ZnS quantum dots were blended into YAG:Ce. Based on spectral evolutions in the blended systems, hybrid white light emitting diodes are fabricated and characterized. -
In this report, cerium doped lutetium aluminate (
$Lu_3Al_5O_{12}$ :Ce) phosphor has been synthesized by the solid state method under reduction atmosphere with mixture gas. The prepared phosphor shows a main luminescent peak at 555nm. Consequently, this phosphor is possible to be applicable to white LED lamp by InGaN chips. -
This presentation introduces a simple strategy for producing 2D photonic crystal layers (PCL) with different structures. In an attempt to improve extraction efficiency from the thin film phosphors (TFPs), this study have examined the effects of the structural variables of the 2D PCLs on the light extraction efficiency of TFPs.
-
In order to improve the contrast ratio of PDPs in the bright room, we decreased the panel reflection by coating phosphors with pigments. In this work, we investigated the panel reflectance with various sizes of the blue pigments and obtained good results by reducing the size of the pigment properly.
-
We report on the Ag thickness effect on the electrical and optical properties of indium zinc tin oxide (IZTO)-Ag-IZTO multilayer electrode grown on a PET substrate and the surface plasmon effect of Ag layer on the optical properties of IZTO-Ag-IZTO electrode. Using an IZTO-Ag-IZTO multilayer with a total thickness below ~80 nm, we can obtain high-quality flexible electrode with very low sheet resistance, high transmittance, high work function and superior flexibility.
-
The preparation and characteristics of flexible indium tin oxide electrodes grown on polyethylene terephthalate (PET) substrates using a specially designed roll-to-roll sputtering system for use in flexible optoelectronics In spite of low a PET substrate temperature, we can obtain the flexible electrode with a sheet resistance of 47.4 ohm/square and an average optical transmittance of 83.46 % in the green region of 500~550 nm wavelength. Both x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis results showed that all flexible ITO electrodes grown on the PET substrate were an amorphous structure with a very smooth and featureless surface, regardless of the Ar/
$O_2$ flow ratio due to the low substrate temperature, which is maintained by a cooling drum. In addition, the flexible ITO electrode grown on the Ar ion beam treated PET substrates showed more stable mechanical properties than the flexible ITO electrode grown on the wet cleaned PET substrate, due to an increased adhesion between the flexible ITO and the PET substrates. -
Characteristics of indium-zinc-oxide (IZO)-Ag-IZO multilayer grown on a PET substrate were investigated for flexible organic emitting diodes. By inserting very thin Ag layer between amorphous IZO, IZO-Ag-IZO (IAI) multilayer anode exhibited remarkably reduced sheet resistance and high transmittance due to the surface plasmon resonance effect and Ag layer.
-
We report on electrical and optical properties of flexible ITO electrode grown on PET substrate using a specially designed roll-to-roll facing target sputtering (R2R FTS) system at room temperature without conventional cooling drum. Due to effective confinement of high density plasma between ITO targets, we can grow a flexible ITO electrode without cooling drum at room temperature.
-
Inorganic-organic hybrid multilayers were formed on the plastic substrate to enhance the barrier properties of substrate to water vapor and oxygen transport. Plasma pretreatment of substrate with
$Ar/O_2$ lead to adhesion improvement and the densification of inorganic layer on the substrates. Combination of$SiO_xN_y$ layer and silanenanoclay composite layer offered quite good barrier properties (WVTR and OTR) to PES substrate. -
Oh, Min-Suk;Lee, Ki-Moon;Lee, Kwang-H.;Cha, Sung-Hoon;Lee, Byoung-H.;Sung, Myung-M.;Im, Seong-Il 620
Transparent electronics has been one of the key terminologies forecasting the ubiquitous technology era. Several researchers have thus extensively developed transparent oxide-based thin-film transistors (TFTs) on glass and plastic substrates although in general high voltage operating devices have been mainly studied considering transparent display drivers. However, low voltage operating oxide TFTs with transparent electrodes are very necessary if we are aiming at logic circuit applications, for which transparent complementary or one-type channel inverters are required. The most effective and low power consuming inverter should be a form of complementary p-channel and n-channel transistors but real application of those complementary TFT inverters also requires electrical- and even photo-stabilities. Since p-type oxide TFTs have not been developed yet, we previously adopted organic pentacene TFTs for the p-channel while ZnO TFTs were chosen for n-channel on sputter-deposited$AlO_x$ film. As a result, decent inverting behavior was achieved but some electrical gate instability was unavoidable at the ZnO/$AlO_x$ channel interface. Here, considering such gate instability issues we have designed a unique transparent complementary TFT (CTFTs) inverter structure with top n-ZnO channel and bottom p-pentacene channel based on 12 nm-thin nano-oxide/self assembled monolayer laminated dielectric, which has a large dielectric strength comparable to that of thin film amorphous$Al_2O_3$ . Our transparent CTFT inverter well operate under 3 V, demonstrating a maximum voltage gain of ~20, good electrical and even photoelectric stabilities. The device transmittance was over 60 % and this type of transparent inverter has never been reported, to the best of our limited knowledge. -
We have investigated the inter-relationship between the ink-jet printability and the physical fluid properties by monitoring the droplet formation dynamics. Printability of the fluids was judged based on the inverse of Ohnesorge number (
$Z^{-1}$ ) that relates to the viscosity, surface tension, and density of the fluid. -
Kuo, Chia-Wei;Lin, Yan-Rung;Wang, Hsing-Lung;Liao, Chi-Chang;Huang, Po-Yu;Shy, Joe-Tsong;Lu, Kevin;Tsai, Afonda;Chang, Rick;Chen, Jerry 627
We have studied the optical performance of flexible polymer network liquid crystal (PNLC) films at various bending states. Different measurement setups, wide and narrow opening angles of detector, were used to collect scatting light of PNLC films. The optical and dynamic properties of bent PNLC implied the change of LC domains. -
Printed organic thin-film transistors (OTFTs) were used in the fabrication of a screen- printed gate, source and drain electrodes on flexible plastic substrates using silver pastes, a coated polyvinylphenol dielectrics, and jetted bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) organic semiconductor. The OTFTs printed using screen printing and soluble processes made it was possible to fabricate a printed OTFT with a channel length as small as
$13\;{\mu}m$ on plastic substrates; this was not possible using previous traditional printing techniques. -
A series novel films of polyimide (PI) and co-polyimide (Co-PI) containing fluorine with colorless, flexible properties was prepared by a two-step process from various commercial aromatic monomers such as 4,4'-(Hexafluoro iso propylidene) diphthalic anhydride (6FDA), 2,2'-Bis(Trifluoromethyl) benzidine (TFDB), 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (AH6FP) and Bis(4-(3-aminophenoxy)phenyl)sulfone (BAS). Furthermore, these obtained transparent and flexible Co-PI films exhibited excellent thermal stability with the decomposition temperature (at 5% weight loss) around of
$500^{\circ}C$ and the glass transition temperature ($T_g$ ) in the range of$275-350^{\circ}C$ . -
The properties of oriented poly(3-hexylthiophene-2,5-diyl) in field effect transistors (FETs) have been investigated through mechanical stretching process as the original. Silicon-based FETs shown high mobility of
$0.02\;cm^2/V$ s after thermal treatment and$0.0092\;cm^2/V$ s at r.t. PET-based FETs were expected to show a similar performance in mobility to that of silicon-based FETs. -
Hu, Guo-Ren;Kung, Bo-Cheng;He, King-Yuan;Cheng, Chi-Hong;Huang, Yeh-Shih;Liu, Chan-Jui;Tsai, Cheng-Ju;Huang, Jung-Jie 641
Traditional LTPS TFT needs additional LDD process to decrease leakage current. However the fabrication process is no suitable for PI substrate. Additional laser multi-irradiation will damage the poly-Si to cause the TFT electrical degrade. Therefore we propose the simplified process to activate the$N^+$ and$N^-$ at the same time. -
In this paper, we analyzed interface trap density between pentacene and PVP and SiO2 gate dielectric by using high-low C-V characteristics. The interface trap density was
$10^{13}\;cm^{-2}eV^{-1}$ . -
We used micro-contact printing for source and drain electrodes of OTFTs. The proper solvent of Ag paste and baking temperature were extracted for PVP gate dielectric and pentacene semiconductor. The mobility was 0.025 cm2/V.sec and on/off ratio was
$2{\times}10^5$ . -
In this paper, we report electrical properties of OTFTs by using ink-jet printing with polyvinylphenol (PVP) for gate insulator and bis(triisopropylsilylenthynyl) pentacene (TIPS pentacene) for semiconductor. OTFTs produced the excellent performance with the mobility of
$1.27\;cm^2/V.s$ for top contact structure(TCS) and inverter consisting of two OTFTs exhibited the gain of 6.75. -
We enhanced the conductivity of PEDOT-PSS by mixing with glycerol and fabricated the low contact resistance of source and drain[S/D] electrodes of OTFT with PEDOT-PSS by ink-jetting printing. The contact resistance was much smaller by seven times than Au with
$200k{\Omega}$ at$V_G=-5V$ . For the bottom contacted OTFTs, the performance was comparable to OTFTs with Au electrodes with the field effect mobility of$0.2\;cm^2/V s$ . -
Barrier coating properties of PVA/
$SiO_2$ on the flexible substrates (PEN) have been investigated. Thin layer of PVA/$SiO_2$ organic-inorganic hybrid materials were deposited on PEN substrate by the spin-coating. The optical properties and surface roughness of barrier layer on flexible substrate were characterized by AFM, UV-Vis and WVTR/ OTR. -
In this study, it was mainly focused on the mechanism and reliability performances of PI/PET composites after many times of curving. We developed a new process of spacer for flexible display to improve the maintenance of cell gap. This new process used the laser carving technology, which is widely applied on printing press, to produce the pattern of spacers and shaped both of the alignment film and spacers simultaneously by press of pattern. Assembling the spacer-shaped film and plastic substrates together well and it shows an excellent performance on the maintenance of cell gap and reliability of curving.
-
Low-temperature curable organic insulator was prepared through blending of polyimide type base resin and cross-linking agent. The newly developed resin can be formed into films using a wet process and cured at
$130^{\circ}C$ . Using the low temperature cured film as the gate dielectric layer, the field effect mobility of$0.15\;cm^2/V{\cdot}s$ was obtained from a pentacene field effect transistor in the saturation regime and no hysteresis behavior was observed in transfer curves. -
With the advancements or LEDs and lasers in projection display applications, arc lamps still provide the most cost effective solution to high brightness display systems. When will arc lamps become obsolete, will be of great importance today and tomorrow? Given the fact that traditional elliptical and parabolic reflectors had been around for decades; Wavien's new dual paraboloid reflector (DPR) technology with its unique imaging property enhances various aspects of the arc lamp performance will shed some light to this question. In this talk, various applications that are feasible today and anticipated needs of tomorrow will be presented.
-
Saran, Neerja;Roh, Nam-Seok;Kim, Sang-Il;Lee, Woo-Jae;Kim, Jong-Seong;Hwang, Tae-Hyung;Hong, Seok-Joon;Kim, Myeong-Hee;Lim, Soon-Kwon;Souk, Jun-Hyung 670
Good mechanical properties of thin-film transistors on plastic substrates are an essential parameter in the development of robust flexible displays. In this paper, a careful investigation is carried out on TFT backplane on plastic substrates under cyclic bending conditions. Bending modes of tensile and compressive as well as parallel and perpendicular orientation-dependent bending of channel have been analyzed carefully. This analysis will be helpful in knowing the electro-mechanical performance boundaries of the TFT devices so as to determine the bending limitations of our flexible displays. -
An electrostatic discharge (ESD) or a noise supplied from the outside has an effect on communication between the timing controller (TCON) and the memory element (EEPROM) through the interface between the timing controller and the memory element in liquid crystal displays (LCD). Therefore, we must apply ESD protection methods to LCD operating circuits for a normal operation. Our ESD protection circuit is to prevent from bi-directional communication errors between TCON and EEPROM due to an electrostatic discharge (ESD).
-
Nam, Hyoung-Sik;Oh, Kwan-Young;Kim, Seon-Ki;Kim, Nam-Deog;Berkeley, Brian H.;Kim, Sang-Soo;Lee, Yong-Jae;Nakajima, Keiichi 677
AiPi technology incorporates an embedded clock and control scheme with a point-to-point bus topology, achieving the smallest possible number of interface lines between a timing controller and source drivers. A 46" AiPi-based 10-bit FHD prototype requires only 20 interface lines, compared to 38 lines for mini-LVDS. The measured maximum data rate per one data pair is more than 800Mbps. -
Motion interpolation is adopted and has been spread widely into market since it is effective in reducing motion blur, which is considered as weak characteristic due to slow response time of liquid crystal and hold-type display. 120Hz driving using interpolated frames achieves better moving picture quality with less motion blur and less motion judder. However, errors in the interpolated frames can cause visual artifacts such as static text breakup, halos, and occlusions. This paper focuses on categorizing characteristics of visual artifacts and on reducing side-effects by using information from original frames in special cases.
-
Mini-LVDS has been widely used for high speed data transmission because it provides low EMI and high bandwidth for display driver. In this paper, a Mini-LVDS output buffer with LTPS TFT process is presented which provides sufficient performance in the presence of large variation in the threshold voltage and mobility and kink effect.
-
Lee, Jae-Beom;Bang, Sung-Yong;Kim, Nam-Deog;Moon, Seung-Hwan;Lee, Yong-Soon;Chung, Eui-Young 689
We present a novel power estimation technique for LCD panels. Our method considers the power consumed by each pixel as well as the inter-pixel power effect of the neighboring pixels. We implemented our method based on the table lookup model and its accuracy is about 98% compared to the actual measurements. -
Maeyaert, Stefaan;Bakeroot, Benoit;Doutreloigne, Jan;Monte, Ann;Bauwens, Pieter;Calster, Andre Van 692
Large area emissive displays have problems with nonuniform pixel characteristics and their individual ageing. A pixel integrated driver with pixel based optical feedback is presented to solve these problems. Photodetectors, optical feedback circuit and data handling capabilities are integrated in a high voltage CMOS technology. -
A 10-bit source driver using low temperature poly-silicon(LTPS) TFTs is developed. To reduce the DAC area, the DAC structure including two 5-bit resistor-string DACs and analog buffer, which has analog adder is proposed. The source driver is fabricated using LTPS process and its one channel area is
$3,200{\mu}m\;{\times}\;260{\mu}m$ . The simulated INL and DNL of output voltages are less than 3 LSB and 1 LSB, respectively. -
A new evaluation method which named 'Security Viewing Angle Factor (SVAF)' was suggested for VIC (Viewing-angle Image Control) technology to quantify a visual hiding performance of LCD. Currently, Contrast Ration (CR) is the general method to evaluate VIC technology. However, CR shows a significant difference when compared with the result of human visual system. Furthermore, a perceptional evaluation method and its conditions were established.
-
Large distortion is made by toed-in camera configuration in the TV condition that has short viewing distance, when the gaze position of a stereoscopic image coincides with that of real space. Therefore, in the TV condition, we confirmed that the proper camera configuration is the modified parallel configuration, and found distortionless optimal stereoscopic image condition using this camera configuration.
-
We proposed the method to present corrected depth cue to an observer by stereoscopic display. It was performed in sequence that designing the displayed space having a constant interval of depth and then defining the object space which had considered to an environment of display and based on computer graphics. Consequently, we had performed a different process of reported existing methods distinctively and taken the result which correctly designed depth cue having linearity whatever various sizes of display would be used.
-
LED Scanning Backlight Stereoscopic Display with Shutter Glasses is provided to realize stereoscopic image viewing even in a liquid crystal display. The eye shutter signal is alternately switched from the left eye to the right eye with 120Hz of LCD Vertical synchronization (V-sync).
-
In this paper, we propose a three-dimensional (3D) integral imaging system using an elastic lens array instead of conventional rigid lens array. The lens array is made of polydimethylsiloxane (PDMS) that is optically transparent and flexible material. We can stretch the PDMS lens array to be expanded into a certain extent, and control the lens pitch of the system easily. That flexible design enables a fine 3D integral imaging display.
-
Novel computational integral imaging technique with enhanced depth sensitivity is proposed. For each lateral position at a given depth plane, the dissimilarity between corresponding pixels of the elemental images is measured and used as a suppressing factor for that position. Experimental and simulation results show that reconstructed depth image on the incorrect depth plane is effectively suppressed.
-
In this paper, we propose a new approach for fast generation of CGHs of a 3-D object by using the run-length encoding and N-LUT methods. In this approach, object points to be involved in calculation of the CGH pattern can be dramatically reduced and as a result a significant increase of computational speed can be obtained.
-
In this paper, we present an interference problem among elemental images in computational integral imaging reconstruction. To overcome the interference problem, we propose a method to calculate a minimum magnification factor and the preliminary experiments are performed.
-
In this paper, a novel CII method using a depth conversion technique is proposed. The proposed method can move a far 3D object near lenslet array and reduce the computation cost dramatically. To show the usefulness of the proposed method, we carry out the preliminary experiment and its results are presented.
-
A method to make the near and far images for a double layer 3D display system to create continuous depth illusion has been studied. The luminance ratio between the near and far images should be allocated based on the tone reproduction characteristics of the display systems.
-
Block-matching motion estimation plays an important role in video coding. In this paper, we propose an Efficient Search Algorithm for Fast Motion Estimation. The proposed algorithm detects motion variation for reducing computational complexity before determining motion vector. Experimental results show that the proposed algorithm has good performance than conventional algorithms through quantitative evaluation.
-
In this paper, tone mapping method by local contrast and detail enhancement for High Dynamic Range (HDR) is proposed. By applying Piecewise Dynamic Range Histogram Adjustment (PDRHA) and Detail Enhancement Volume (DEV) with decomposed layers, tone mapping is performed effectively. The experimental results show that the proposed method preserves local contrast and overall impression with naturalness of original images.
-
The theory of Bartleson and Breneman that the perceived image contrast changes with surround luminance (the lighter surround provides higher contrast) was tested an over bright condition(
$8500d/m^2$ ). Contrarily to the Bartleson and Breneman's results, we observed the fact that perceived constrast was decreased when surround huminance increased from dark to over bright through two sets of psychophysical experiments based upon both uniform gray patches and complex color images. -
Various Motion Estimation (ME) algorithms have been proposed since ME requires large computational complexity. The proposed algorithm employs Enhanced Cross Search Pattern (ECSP) using motion vector of neighbor-blocks to search the motion vector. The experimental results show that proposed algorithm reduces the search point up to 35% compared to conventional methods.
-
Ahn, Ji-Young;Kang, Dong-Woo;Park, Sun-Ah;Shin, Kwang-Hoon;Moon, Jong-Won;Lim, Moo-Jong;Shin, Hyun-Ho 753
We analyzed the problem of the typical definition of the viewing angle, where the contrast ratio is higher than 1:10 and suggest the new definition of the viewing angle by considering the contrast ratio, color shift, luminance and gamma shift in the viewing direction all together. -
In this paper, an improved computational integral imaging reconstruction (CIIR) is proposed. The proposed method can highly enhance the viewing quality of reconstructed image. To show the feasibility of proposed method, some experiments are performed and the results are compared and discussed with those of the conventional method.
-
In this paper, a novel approach for robust recognition of partially occluded 3-D target objects from computationally reconstructed integral images is proposed. The occluding object noises are selectively removed from the picked-up elemental images and performance of the proposed integral imaging-based 3-D target recognition system can be improved.
-
3D displays requires multiplexing of left and right pictures on the same screen so that they can be viewed independently by the view using various schemes, including LCD shutters, polarizers, narrow band filters, and lenticular lenses on the screen. All these methods reduce the effective screen brightness by as much as 10X. The eye responses to the lower brightness are analyzed and found to compensate partially giving a lower perceived brightness. This paper presents such eye response analysis and a low cost approach to increasing brightness in a RPTV using the long life DPR system, increasing the screen brightness by over 2.5 times, while maintaining acceptable lamp lifetime.
-
To make 3D camera system, we check the possibility of advanced range camera module based on measuring the time delay of modulated infrared light, using a single detector chip fabricated on standard CMOS process. To depth information, electronic shutter and interlaced scanning method of 2D sensor is needed. Especially, we design "lens system, illumination unit" and review simulation result.
-
For several years, many researchers have proposed LED backlight dimming technology for low power consumption and high contrast ratio. One of the major issues plaguing RGB LED with 2D dimming technology is color shift. This undesirable variation makes it difficult to use RGB LED as light sources in the backlight system. This paper describes the useful method of the optical feedback system for 2D dimming RGB LED backlight. The test results show that our proposed method is very suitable for the 2D dimming technology.
-
We have developed new in-cell retarder materials that provide good transmittance and resolution with the goal of enhancing the properties of transflective IPS-LCDs. We explored various additive surfactants to optimize the applicability of the materials. Moreover, we selected photopolymerization initiators and liquid crystal diacrylate monomers as negative-type photo-patternable retarder materials, seeking to improve resolution and transmittance.
-
-
Low-loss optical films can be used in LCD backlights to improve the display efficiency. Improvements can be used to enhance display performance, increase functionality and reduce energy costs.
-
Synthesis and luminescent properties of
$Eu^{3+}$ -doped$YVO_4$ by using a mild hydrothermal processNanoscale$YVO_4:Eu^{3+}$ phosphor has been synthesized by a mild hydrothermal reaction at various experimental conditions. The particle and luminescent properties of nanophosphors were characterized with X-ray diffraction, electron microscopy and photoluminescence. It has been found that pH value play a key factor both controlling particle size and luminous efficiency. -
ZnO nanoparticle was successfully prepared by microwave irradiation method in various oxygen/nitrogen ratio atmospheres. The product prepared in a low oxygen ratio atmosphere showed tetra pod shape with high aspect ratio, c/a. PL spectra of the products showed higher UV emission intensity than the others when it was prepared in the atmosphere oxygen/nitrogen=40/60.
-
Kim, Hyung-Dong;Jeon, Hyun-Woo;Lee, Chang-Ho;Yoon, Jung-Hyun;Kim, Jae-Bum;Lim, Jong-Ho;Shin, Jong-Keun;Chung, In-Jae 792
We investigated influence of gas pressure and mixing ratio on the electro-optical properties of External Electrode Fluorescent Lamp (EEFL). The experimental results indicated that luminance and efficiency became the maximum at lower gas pressure and Ar mixing ratio. -
The discharge characteristics of a flat plasma backlight with long electrode gap are investigated. The effect of operating voltage and repetition rate on brightness and luminance efficiency is investigated. A new high efficacy mode is found at low frequencies around 15-40 KHz; a lumen efficacy of 15.3 lm/W is achieved at a luminance of
$2400\;cd/m^2$ . In the high brightness mode, present at high voltage, we find a maximum luminance of$5900\;cd/m^2$ at 30KHz. -
The metal films ink-jetted using the conductive ink based on a mixture of copper and silver nanoparticles were investigated. The porosity and resistivity of films were minimized by adjusting the mixing ratio of Cu and Ag nanoparticles. We demonstrated that the printed tracks with good conductivity could be obtained at sufficiently lower annealing temperatures where plastic substrates could be used.
-
For the life estimation of CCFLs in edge-lit LCD modules has been required CCFL blackening test, which is executed in the state of low current and long-time operation under the high temperature condition. We investigated the reason why CCFL blackening happened more easily in the above test conditions and the way how mechanical parts had influence upon CCFL blackening in the edge-lit LCD modules.
-
We studied ink-jet printing for selective deposition of soluble oxide semiconductor to fabricate transistor. Sol-gel derived ZTO solution was synthesized for ink-jet printable solution. Transistors were produced by printing oxide layer between ITO electrodes. We demonstrated that ink-jet printed ZTO transistors work well and surface treatment significantly influences device performance.
-
Structural parameter variation effects (changing the coplanar gap under different discharge dimensions) and use of complex gas mixtures (He, Ne, Ar and Xe) in mercury-free fluorescent lamps are studied in this paper. Pure Neon gas is the best buffer gas for obtaining high luminous efficiency in mercury-free fluorescent lamps. It is shown that with a shorter coplanar gap (30mm), a high luminous efficiency can be obtained at low operating voltage, as well as high luminance uniformity and stable discharge with a Ne-Xe 20% gas mixture.
-
Ryu, Min-Ki;Kopark, Sang-Hee;Hwang, Chi-Sun;Shin, Jae-Heon;Cheong, Woo-Seok;Cho, Doo-Hee;Yang, Shin-Hyuk;Byun, Chun-Won;Lee, Jeong-Ik;Chung, Sung-Mook;Yoon, Sung-Min;Chu, Hye-Yong;Cho, Kyoung-Ik 813
We prepared highly transparent and conductive Oxide/Metal/Oxide(OMO) multilayer by sputtering and developed wet etching process of OMO with a clear edge shape for the first time. The transmittance and sheet-resistance of the OMO are about 89% and$3.3\;{\Omega}/sq.$ , respectively. We adopted OMO as a gate electrode of transparent TFT (TTFT) array and integrated OLED on top of the TTFT to result in high aperture ratio of bottom emission AM-OLED. -
A negative photoresist formulation was developed utilizing synthesized UV monomers containing imide linkage, photoinitiator, UV oligomer, and alkali developable polymer matrix. It was found that via-holes with good resolution, high transmittance and thermal resistance could be obtained by photolithographic process utilizing the negative-type photoresist formulations.
-
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 derivative was synthesized and characterized. The properties of the compound were characterized by FT-IR, NMR and we measured the charge transport mobility and the on/off current ratios.
-
Phosphate glass added the various alkali additives is one of the substitutive materials for the barrier-ribs in plasma display panel. The results of differential thermal analysis and coefficient of thermal expansion show that the alkali oxides affect the thermal properties of phosphate glass.
-
We proposed a new Mercury-free flat fluorescent lamp (MFFL) for LCD backlight which has the scanning ability to reduce the blurring edges of moving images. We expanded the single cell MFFL with 2.2 inch diagonal size into the multi-cell MFFL for the 32-inch LCD-TV backlight application, and examined its response characteristics and proposed a driving scheme for scanning.
-
150 nm thick Ga-doped ZnO thin film, which was deposited by a sputtering process, was wet-chemically etched by using various organic acids such as oxalic, citric and formic acid. Wet etch parameters including etchant concentration and temperature are investigated for each etchant, and their effects on the etch rate and the feature of edge line are compared.
-
Lee, Kwang-Ho;Kim, Sang-Mook;Kim, Ki-Seok;Song, Sun-Sik;Kim, Eun-Uk;Jung, Hee-Soo;Kim, Jin-Ju;Jung, Gun-Young 834
We demonstrated micro-scale conducting polymer patterning based on a selective surface treatment. A substrate with a patterned photoresist was immersed into OTS (Octadecyltrichlosilnae) solution. The protected substrate areas were hydrophilic after removing the PR resist, where a conducting polymer solution was coated selectively by spin-coating method. -
This paper studies the current regulator of LED Backlighting system for LCD. The proposed regulator and a typical regulator are introduced. To find out the characteristics of two regulators, Prototype samples of LED Backlighting system are made. Both the proposed regulator and a typical regulator are compared with electrical, thermal and optical characteristics each viewpoint.
-
We elucidated a way to increase the mobility of
$\pi$ -stacked materials by comparing various single-crystal OFETs. A high field-effect mobility (of$3.7\;cm^2/Vs$ ) was obtained by increasing the effective$\pi$ -stacking area and decreasing the$\pi$ -stacking distance. -
A new p-type conjugated copolymer, poly(9,10-diethynylanthracene-alt-9,9-didodecylfluorene (PDADF) was synthesized through a Sonogashira coupling reaction. A solution-processed thin film transistor device showed a carrier mobility value of
$6.0\;{\times}\;10^{-4}\;cm^2/Vs$ with a threshold voltage of -17 V and a capacitance ($C_i$ ) of$10\;nF/cm^2$ . -
Three thermally stable red dyes of azo, quinacridone and perylene derivatives were synthesized and dye-based color filters were manufactured for liquid crystal display. Aggregation behavior of the dyes and their spectral property in film state were investigated by concentration dependent spectroscopy and field emission scanning electron microscopy (FE-SEM). These dyes have remarkable difference on their aggregation behavior in film state. Such difference of aggregation behavior affects the spectral property of the film, and it can cause decreasing the transmittance of dye-based color filters.
-
In order to reduce the manufacturing cost of TFT LCDs and cut down an amount facilities invested, there are many LCD panel makers contributes to convert the current Five-mask manufacturing process into the noble Four-mask fabrication process. We optimized the slit mask to improve the poor process reliability.
-
Peng, Kang-Yung;Yin, Hsueh-Min;Lin, Yang-Chu;Wang, Yang-Long;Kung, Li-Wei;Chan, Meng-Xi;Cheng, Hsin-An;Liau, Wei-Lung;Lien, Alan 855
Transient current (TC) on bulk-state liquid crystal mixtures was measured. We found that TC is very sensitive to impurities and the features of TC curves depend on the type of contamination, from which the quality of materials can be definitely evaluated and the type of impurities can also be revealed. -
We present a new tool to measure precisely the emissive properties of displays at the pixel level with submicrometric spatial resolution. It is useful to check the technological defects and their impact on the emissive properties of the displays. Backlight films and transflective and reflective displays are measured.
-
For the cost reduction in the fabrication of display panels, a reverse moving system was equipped to a compacted in-line wet etch/cleaning system. For the effect of the alternating movement of substrate on the wet etch process, ITO layers were etched in various moving modes of substrates and the results were compared and analyzed.
-
Bang, J.H.;Ahn, Y.K.;Ryu, W.S.;Kim, J.O.;Kang, Y.K.;Yang, J.Y.;Yang, M.S.;Kang, I.B.;Chung, I.J. 867
We have investigated the effects of hydrogen plasma treatment by PECVD (Plasma Enhanced Chemical Vapor Deposition) in the back channel region, the method for reducing the off state leakage current which increases with the short channel length of a-Si:H TFTs. To improve the off current characteristics, we analyzed the hydrogen plasma treatment with various RF power and plasma treatment times of PECVD. As the result of hydrogen plasma treatment in the back channel region it was remarkably reduced the off current level of 2um channel length TFT. -
It is known that AC electric field to drive IPS mode of liquid crystal display (LCD) causes reduction of the contrast after long period of display operation. Our results are presented in this paper on a base of a model of interaction between surface of PI alignment film and LC molecules. We conclude that the surface viscosity of PI alignment film is one of the most important factors for the contrast reduction phenomenon.
-
Doosan Mecatec has developed alignment system for Organic Light-Emitting Diode (OLED) display production using large size substrate. In the present article, The alignment system between the substrate and the mask, which is a core technology for producing the OLED product using the fourth-generation substrate with
$730{\times}920mm^2$ or more, will be described by dividing into a substrate loader, a magnet unit, a CCD camera, etc. The substrate loader is optimized through the simulation where the central portion of the substrate droops by about 1.5mm by clamping each of a long side (920mm direction) and a short side (730mm direction) thereof by 6 point and 4 point. A magnet unit using a sheet type of rubber magnet is constituted and a CCD camera model with the specifications capable of minimizing the errors between a clear image and the same image is selected. The system to which an upward evaporation technique of small molecular organic materials will be applied has been developed so that repeatability and position accuracy becomes${\pm}1{\mu}m$ or less using an UVW type of stage. Also, the vision accuracy of the CCD camera becomes${\pm}1{\mu}m$ or less and the align process TACT becomes 30sec. or less so that the final alignment accuracy between the substrate and the mask becomes${\pm}3{\mu}m$ or less. In order to meet an extra-large glass substrate, an evaporation system using an extra-large AMOLED substrate has been developing through a vertical type of an alignment system. -
The discotic liquid crystal in compensating film used for the viewing angle improvement of the twist nematic liquid crystal display panel is analyzed. For the optical characterization of the compensating film, we measured the polarization state of the light passing through the film as the tilt angle and the azimuth angle of the film were varied, and then we compared the measured polarization state with the calculated one. Finally we suggested the best fit configuration of the discotic liquid crystal.
-
Jang, Won-Gun;Park, Byoung-Choo;Kim, Min-A;Kim, Sun-Woong;Kim, Yun-Ki;Choi, Eun-Ha;Seo, Yoon-Ho;Cho, Guang-Sup;Kang, Seung-Oun;Takezoe, Hideo 883
In optical information technology, an electro-controllable Photonic Band Gap (PBG) in a photonic crystal (PC) material is potentially useful for the manipulation of light. Despite a great deal of research on PBGs, the reliable use of electro-active PBG material systems is restricted to only a few cases because of the complex and limiting nature of the structures involved. Here, we propose a PBG system that uses a liquid crystal (LC) polymer composite. The composite is made of nematic LCs (NLCs) embedded in polymeric helical networks of photo-polymerized cholesteric LCs (CLCs). The composite film shows a large field-induced reversible color shift over 150 nm of the reflection band, due to the reorientational undulation of the helical axis, similar to the Helfrich effect. -
We present 2D slab silicon-based photonic crystal optical insulator to enhance light emission efficiency of light-emitting diode (LED). A 2D slab silicon photonic crystal is designed in such a way that light emitting diode die can be placed in the middle of the silicon photonic crystal. The device creates light propagation forbidden region in horizontal plane for Transverse Electric (TE) light with the wavelength range of 450 nm to 600 nm.
-
Noh, Chang-Ho;Jang, Jae-Eun;Jung, Jae-Eun;Lee, Ji-Min;Jeon, Seog-Jin;Das, Rupasree Ragini;Han, Jai-Yong;Kim, Jong-Min;Son, Seung-Uk;Park, So-Youn;Moustafa, Walid S.A. 891
Here we describe the new structured electrochromic(EC) materials to improve the three primary colors (RGB). We also report the simply isolated electrochromic unit cell using gel type electrolyte and show cross-talk' free driving of EC display device. -
ZnO films were fabricated using rf-magnetron sputter deposition process with different
$N_2$ ambient. N-content in N-doped ZnO films was less than 1%. The wavelength of the highest intensity PL peak of N-doped ZnO was shifted to higher wavelength with increasing$N_2$ flow rate in the deposition ambient. These results indicated that the optical property of ZnO was significantly affected by the defect level created by doping with a very small amount of N. -
In this paper we propose a new method for obtaining two way switchable LCD. For this two domain vertical alignment LCD is used. A two way LCD is able to show different images on the same screen based on left and right perspectives. Viewing angle dependence of different grey levels of transmittance for the polar angles 0, +45 and -45 degree are also found out.
-
Kaitoh, Takuo;Miyazawa, Toshio;Miyake, Hidekazu;Noda, Takeshi;Sakai, Takeshi;Owaku, Yoshiharu;Saitoh, Terunori 903
We developed the advanced LTPS (A-LTPS) manufacturing process. The a-Si TFT process was combined with selectively enlarging laser crystallization (SELAX) technology to improve the carrier mobility in the region where the peripheral circuits are to be fabricated. A 2.4-inch IPS-pro LCD panel for personal digital assistant use was successfully fabricated using the developed technology. -
The effect of channel length reduction on the electrical characteristics of self-aligned polysilicon TFTs has been investigated by combining experimental characteristics and 2-D numerical simulations. The role of drain induced barrier lowering and floating body effects has been carefully analized using numerical simulations.
-
In this work, nonvolatile memory (NVM) devices for system on panel of flat panel display (FPD) were fabricated using low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) technology with an oxide-nitride-oxynitride (ONOn) stack structure on glass. The results demonstrate that the NVM devices fabricated using the ONOn stack structure on glass have suitable switching characteristics for data storage with a low operating voltage, a threshold voltage window of more than 1.8 V between the programming and erasing (P/E) states after 10 years and its initial threshold voltage window (
${\Delta}V_{TH}$ ) after$10^5$ P/E cycles. -
A quad-functional built-in test circuit has been developed for DRAM-frame-memory embedded SOG-LCDs. The quad function consists of memory test, display test, serial transfer test, and parallel transfer test which is the normal operation mode for our SOG-LCD. Results of memory and display tests are shown.
-
We investigated new deep blue emitting materials including a novel side group such as CB-203. CB-203 shows relatively 40% increased PL quantum efficiency and higher Tg of
$30^{\circ}C$ compared to MADN. It exhibits high External Quantum Efficiency (EQE) of 7.18% that is two times bigger than MADN's, which is the best efficiency in case of non-doped blue fluorescence OLED device to our knowledge. And deep blue emitting materials with a new core structure (CB-301) have been synthesized. CB-301 exhibit excellent blue fluorescence properties. Undoped OLED devices using CB-301 as blue emitters was found to deep blue CIE value (0.154, 0.078) and exhibit high luminance efficiencies of 2.01cd/A at$10\;mA/cm^2$ . -
Vestweber, Horst;Gerhard, Anja;Kaiser, Joachim;Heil, Holger;Kroeber, Jonas;Pflumm, Christof;Stoessel, Philipp;Joosten, Dominik;Buesing, Arne;Fortte, Rocco;Parham, Amir;Boehm, Edgar 925
In order to improve the performance in green phosphorescent OLED devices, Merck has developed novel host and electron blocking materials. The newly developed host materials improve the device lifetime by a factor of 3. The newly developed electron blocking materials having not only electron but also exciton barrier properties increase the efficiency of the device by a factor of 1.4. Comparable results were achieved in phosphorescent red systems with further host materials. -
Park, Tae-Jin;Park, Jung-Joo;Kim, Gyeong-Heon;Jeon, Woo-Sik;Pode, Ramchandra;Jang, Jin;Kwon, Jang-Hyuk 928
Using 4,4'4"-tris(N-carbazolyl)-triphenylamine (TCTA) small molecule interlayer, we have fabricated efficient green PHOLED by solution process. The maximum current and power efficiency values of 33.7 cd/A and 19.6 lm/W are demonstrated, respectively. Results reveal a way to fabricate the PHOLED using TCTA interlayer by solution process, promising for efficient and simple manufacturing. -
Three-dimensional (3D) display systems based on wavefront reconstruction are presented. To obtain the wavefront of 3D objects, we present holographic recording using temporally or spatially phase-shifting interferometer. In the 3D display systems, phase-only reconstruction using a spatial light modulator and an approach to increase the reconstructed power are presented.
-
Moir
$\acute{e}$ s are a natural interference phenomenon which occurs whenever a transparent regular pattern plate is overlapped on another regular pattern plate. In the contact-type 3 dimensional imaging systems, the moires are inherent because an image display panel is seen through a viewing zone forming optical plate. The mathematical analysis of moires in the systems shows that they can be minimized by the proper selection of overlapping angles between them. The angle is different for pixels with different aspect ratios. -
Many works have been done to enable computer, as brain of robot, to learn color categorization, most of them rely on modeling of human color perception and mathematical complexities. This paper aims at developing the innate ability of the computer to learn the human-like color categorization.
-
This paper reports of traceable and repeatable time resolved colorimetric measurements of the luminance- and colour variation occurring during the frame refresh period of FPD's. During one frame period a number of measurements are performed, and for the dynamic artifacts a simulated smooth pursuit eye tracking algorithm is included.
-
Using the theoretical model of Auger electron emission, effects of MgO properties which include band gap energy, escape probability, gas ion, and doping elements on the yield of secondary electron emission were examined. The results indicated that the band gap of MgO must be decreased and escape probability must be enhanced in order to increase the yield of secondary electrons from Xe ions and that may proved to be a critical for achieving high luminance efficacy in ac-PDPs.
-
The influences of silicon and MgO seed particle on the reconstruction characteristics of MgO protective layer were investigated to clarify the mechanism of reconstruction and exaggerated grain growth (EGG) in AC-PDP. The reconstruction and EGG are closely correlated with the driving force for nucleation and growth, interface energy and initial size distribution of MgO protective layer in plasma space during discharge in AC-PDP.
-
The MgO protective layer of PDP has a strong influence on address delay. The relation, however, is not clearly understood due to the difficulty of analysis which is caused by surface charging. This paper suggests a way to avoid the charging problem and shows the correlation between workfunction measured by UPS and address delay.
-
Jeong, Sang-Cheol;Jeong, Jong-In;Kim, Jeong-Jun;Song, Min-Ki;Kim, Ki-Bum;Mo, Bu-Kyung;Woun, Yong-Kyun;Yoon, Chang-Bun 965
MgO thin film is widely used in PDP panel for protecting the dielectric layer and making firing voltage low. In this paper, the MgO thin film and discharge characteristics was analyzed as hydrogen flow rate increasing. Using hydrogen in deposition chamber makes add delay time of PDP module longer or shorter. It is the reason why thin film surface layer thickness on the MgO surface changes. -
Ju, Sang-Hyun;Liu, Jun;Li, Jianfeng;Chen, Po-Chiang;Zhou, Chongwu;Facchetti, Antonio;Janes, David B.;Marks, Tobin J. 973
Optically transparent and flexible electronic circuits and displays are attractive for next-generation visual technologies, including windshield displays, head-mounted displays, and transparent screen monitors. Here we report on the fabrication of transparent transistors and circuits based on the combination of nanoscopic dielectrics and organic, inorganic, or hybrid semiconductors. Furthermore, the first demonstration of a transparent and flexible AMOLED display driven solely by$In_2O_3$ nanowire transistors (NWTs) is reported. The display region exhibits an optical transmittance of ~35% and a green peak luminance of${\sim}300\;cd/m^2$ . These results indicate that NWT-based drive circuits are attractive for fully transparent display technologies. -
Novel sulfur-containing aromatic compounds were developed as stable, high-performance organic semiconductors for OTFT applications. Of them, dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) consisting of six aromatic rings gave high quality thin films by vapor deposition, which acted as a superior FET channel showing FET mobility as high as
$3.0\;cm^2V^{-1}s^{-1}$ . On the other hand, highly soluble 2,7-dialkyl[1]benzothieno[3,2-b][1]benzothiophenes ($C_n$ -BTBTs) gave solution-processible OTFTs with FET mobility higher than$1.0\;cm^2V^{-1}s^{-1}$ . -
Han, Seung-Hoon;Kim, Yong-Hee;Kim, Sung-Hoon;Kim, Chang-Hyun;Jeon, Tae-Woo;Lee, Sun-Hee;Choi, Min-Hee;Choo, Dong-Jun;Jang, Jin 979
We studied hybrid passivation using parylene-C, metal, photoacyl and indium zinc oxide for pentacene OTFT to assure stability in subthreshold region. After the passivation, the changes in S and$V_{on}$ of OTFT were negligible and$I_{off}$ maintained its initial value of${\sim}10^{-12}$ A. Therefore, the hybrid passivation is suitable for practical applications based on OTFT. -
Metal induced crystallization of a-Si with a source of Ni/Si oxide was studied. Its mechanism to induce crystallization was discussed. It was found that new source behaves an effect of self-released nickel and reducing nickel residua, so can provide a wider process tolerance; improve the uniformity and stability of TFTs.
-
X-ray lithography is one of the most powerful processes in the fabrication of nano/micro structures with a high aspect ratio. This process enables the fabrication of ultra-thin barrier ribs for PDP using X-ray sensitive paste. In this paper, organic material including photo-monomers, photo-oligomers, binder polymer and additives as well as inorganic powders with different size were optimized to fabricate high aspect ratio barrier rib pattern for PDP.
-
Electrochromic (EC) devices are capable of reversibly changing their optical properties upon charge injection and extraction induced by the external voltage. The characteristics of the EC device, such as low power consumption, high coloration efficiency, and memory effects under open circuit status, make them suitable for use in a variety of applications including smart windows and electronic papers. Coloration due to reduction or oxidation of redox chromophores can be used for EC devices (e-paper), but the switching time is slow (second level). Recently, with increasing demand for the low cost, lightweight flat panel display with paper-like readability (electronic paper), an EC display technology based on dye-modified
$TiO_2$ nanoparticle electrode was developed. A well known organic dye molecule, viologen, was adsorbed on the surface of a mesoporous$TiO_2$ nanoparticle film to form the EC electrode. On the other hand, ZnO is a wide bandgap II-VI semiconductor which has been applied in many fields such as UV lasers, field effect transistors and transparent conductors. The bandgap of the bulk ZnO is about 3.37 eV, which is close to that of the$TiO_2$ (3.4 eV). As a traditional transparent conductor, ZnO has excellent electron transport properties, even in ZnO nanoparticle films. In the past few years, one-dimension (1D) nanostructures of ZnO have attracted extensive research interest. In particular, 1D ZnO nanowires renders much better electron transportation capability by providing a direct conduction path for electron transport and greatly reducing the number of grain boundaries. These unique advantages make ZnO nanowires a promising matrix electrode for EC dye molecule loading. ZnO nanowires grow vertically from the substrate and form a dense array (Fig. 1). The ZnO nanowires show regular hexagonal cross section and the average diameter of the ZnO nanowires is about 100 nm. The cross-section image of the ZnO nanowires array (Fig. 1) indicates that the length of the ZnO nanowires is about$6\;{\mu}m$ . From one on/off cycle of the ZnO EC cell (Fig. 2). We can see that, the switching time of a ZnO nanowire electrode EC cell with an active area of$1\;{\times}\;1\;cm^2$ is 170 ms and 142 ms for coloration and bleaching, respectively. The coloration and bleaching time is faster compared to the$TiO_2$ mesoporous EC devices with both coloration and bleaching time of about 250 ms for a device with an active area of$2.5\;cm^2$ . With further optimization, it is possible that the response time can reach ten(s) of millisecond, i.e. capable of displaying video. Fig. 3 shows a prototype with two different transmittance states. It can be seen that good contrast was obtained. The retention was at least a few hours for these prototypes. Being an oxide, ZnO is oxidation resistant, i.e. it is more durable for field emission cathode. ZnO nanotetropods were also applied to realize the first prototype triode field emission device, making use of scattered surface-conduction electrons for field emission (Fig. 4). The device has a high efficiency (field emitted electron to total electron ratio) of about 60%. With this high efficiency, we were able to fabricate some prototype displays (Fig. 5 showing some alphanumerical symbols). ZnO tetrapods have four legs, which guarantees that there is one leg always pointing upward, even using screen printing method to fabricate the cathode. -
Lamp mura has become a challenge for slim LCD-TV backlight design. The aim of this paper is to apply a novel diffuser plate to improve lamp mura issue instead of increasing lamps or optical films. The results are positive and contribute to the design of slimmer TV without cost up.
-
An advanced backplane circuit technology for AMOLED using amorphous silicon TFTs with commercial level reliability, uniformity and lifetime was recently integrated into a prototype device. Differential aging of T98>100 hrs at 200 cd/m2 brightness and >10,000hrs lifetime is demonstrated. A 2.2" QVGA (
$240{\times}320$ ) prototype has been developed and shown having the above-mentioned high performance. -
Electronic Paper Displays (EPDs) incorporating electrophoretic foils have made digital reading as pleasant as reading normal print. We will report on progress to replace glass-based displays with light and robust plastic EPDs using only a few extra process steps in a standard TFT-LCD factory.
-
Park, Kwon-Shik;Cho, Nam-Wook;Chun, Min-Doo;Moon, Tae-Woong;Jang, Yong-Ho;Kim, Hea-Yeol;Kim, Binn;Choi, Seung-Chan;Cho, Hyung-Nyuck;Ryoo, Chang-Il;Yoon, Soo-Young;Kim, Chang-Dong;Kang, In-Byeong 1009
We have succeeded in producing the world$1^{st}$ TFT LCD panel adapting the data line sharing method. In the data line sharing structure, two neighboring pixels share one data line. We also adapted time shared data driving with a-Si TFT based circuit integration technology of LG Display's own. By using these technologies, we can reduce the number of source driver ICs by half, compared to that of the existing gate driver integrated TFT LCD panel. -
Tandem organic light-emitting diodes (OLEDs) do not always improve power efficiency over their conventional OLED counterparts. When a tandem OLED utilizes optimized EL units, increased power efficiency can only be achieved if the intermediate connector in the device has excellent charge injection capability.
-
Multilayer transparent electrodes (MTE) based on an ultrathin metal layer assisted by additional dielectric or semiconducting layers are investigated as electrodes in OLEDs including an inverted geometry. A special attention is paid to their tuning capability in injection behavior and to their potential for ultra-flexible electrodes.
-
Kim, Hyun-Jong;Yang, Ji-Hoon;Ye, Seok-Min;Jeong, Jae-Wook;Chang, Seung-Wook;Boris, Crystal;Chung, Ho-Kyoon;Lee, Chang-Hee;Hong, Yong-Taek 1022
To the best of our knowledge, for the first time, we applied impedance spectroscopy to analysis on OLED degradation mechanism by monitoring impedance change during constant voltage aging, and modeling OLED with lumped circuit elements. Change in each element value was used to explain charge accumulation and field redistribution in each organic layer. -
Temperature increase during OLED operation can significantly degrade the device lifetime. By using top-emission OLEDs fabricated on glass and silicon substrates that have different thermal conductivities, we found that efficient heat dissipation and corresponding lifetime improvement can be obtained by making a direct contact between the OLED anode and the high thermally-conductive silicon substrate. We describe substrate-dependent OLED heat dissipation behavior and OLED lifetime improvement by using infrared camera images and constant current stress test methods.
-
In this paper, we describe the development of the polarized-light stereoscopic monitoring system based on full HDTV. The system consists of the stereoscopic camera part, image processing device for the stereoscopic image recording and stereoscopic display. The developed stereoscopic imaging display system reduces eyestrain and viewer fatigue.
-
Kim, Jae-Shin;Chong, Jong-Ho;Kim, Sang-Ho;Kim, Gun-Shik;Bae, Jae-Woo;Lee, Seung-Bae;Oh, Jun-Sik 1039
We propose a novel method to measure moving picture quality of display. This method simulates human visual system based on CSF (Contrast Sensitivity Function). And it evaluates moving picture quality of display on the image captured by pursuit camera. The results from this method are correlated with human visual perception test very well. -
In this paper, we propose a Motion Estimation (ME) using new blocks based on the Frame Difference (FD) between two adjacent frames for Frame Rate-up Conversion (FRC). The proposed algorithm decides the shape of blocks by the FD. The experimental results show that the proposed method has better performance than conventional methods.
-
Kubo, Momoji;Serizawa, Kazumi;Kikuchi, Hiromi;Suzuki, Ai;Koyama, Michihisa;Tsuboi, Hideyuki;Hatakeyama, Nozomu;Endou, Akira;Takaba, Hiromitsu;Kajiyama, Hiroshi;Shinoda, Tsutae;Miyamoto, Akira 1049
We developed novel molecular dynamics and quantum chemical molecular dynamics simulators for the design of MgO protecting layer in plasma display panel. These simulators were applied to the investigations on the destruction processes of the MgO protecting layer as well as the evaluation of its second electron emission ability. From the simulation results, we successfully proposed new guidelines for MgO protecting layer with high durability and high second electron emission ability. -
The effects of wall charge and bias voltage on exo-electron emission currents were examined. In addition, the effects of doping elements on the currents were investigated. These results indicated that the statistical delay is inversely proportional to the exo-electron emission currents measured.
-
Study of the ion-induced-, photo- and exo-electron emission from a Sc doped MgO protective layer has been performed. It is established that doping with Sc increases photo- and especially exo-electron emission from MgO films while the ion-induced electron emission coefficient
$\gamma$ stays unchanged. -
Wagner, Sigurd;Mandlik, Prashant;Han, Lin;Silvernail, Jeff A.;Ma, Rui-Qing;Hack, Michael;Brown, Julie J. 1063
We have discovered a new single-layer environmental barrier for OLEDs. In storage at$65^{\circ}C$ and 85% relative humidity, OLED pixels encapsulated with this barrier have half-lives of approximately one year. We describe the fabrication and properties of the barrier, and results of accelerated storage tests. -
Printed thin-film transistors (TFTs) have received profound interests as an alternative to their silicon counterparts for use in fabricating next-Gen microelectronics by virtue of projected low manufacturing cost and certain salient features (e.g., thin and lightweight characteristics, structural flexibility, etc.) that printed TFTs bring to device architecture. The economic advantages stem from engaging low-cost printing techniques (e.g., screen printing, gravure, flexography, etc.) for deposition and patterning in place of traditionally costly high-vacuum, high-temperature photolithographic processes. To render printing TFTs possible, solution processable materials are necessary.
-
Adam, Raymond;Eveson, Robert;Macdonald, Bill A;Mackerron, Duncan;Hodgson, Andrew;Rakos, Karl;Rollins, Keith;Rustin, Bob A;Looney, M Kieran;Haapala, Jaana;Hashimoto, Katsuyuki 1067
DuPont Teijin FilmsTM have developed engineered substrates for flexible electronics. Teonex(R) Q65 and Melinex(R) ST506/5004 are biaxially oriented semi-crystalline polyesters. Smooth planarised Teonex(R) Q65 and Melinex(R) ST506/504 emerge as suitable substrate materials for display backplanes and frontplanes. This contribution discusses the impact of applying a planariser coating to these films. Also, the effect of a more controlled finishing process treatment upon film shrinkage and CLTE is presented. -
By carefully selecting the structure of dyes, especially the metal complex dyes, and studying the properties of the prototype display. It was found some dyes electrophoresis and display well. The dyes ink with good stability during electrophoresis when the electrode was protected. while the response time is about 300 ms.
-
Jeng, Shie-Chang;Kuo, Chia-Wei;Lin, Yan-Rung;Wang, Hsing-Lung;Liao, Chi-Chang;Yang, Chen-Yu;Hwang, Shug-June 1077
Nanoparticles-induced vertical alignment (NIVA) in the liquid crystal (LC) devices was observed and has been applied successfully on fabricating the hybrid-aligned nematic LC cells and guest-host LC cells. In this talk, we will discuss the characteristics of the electric and optical properties of NIVA-LC cells with different dopant concentrations and demonstrate that nanoparticles can be spin-coated on the substrate at a low temperature. -
An ultra-thin reflective flexible LCD film has been demonstrated. The 30% thickness of the display can be reduced by applying a quarter-wave-plate film as upper substrate. A low temperature alignment material and special designed photo spacer were applied in this new display. The bending behavior was improved by reduced thickness.
-
Lazarev, Alexander;Geivandov, Artur;Kasianova, Irina;Kharatiyan, Ellina;Lazarev, Pavel;Palto, Sergey 1083
Crysoptix KK has developed low-cost coatable retarder technology. A full range of coatable retardation films with tunable value of biaxiality (NZ factor) has been developed for the first time. Tunable NZ factor allows efficient compensation of modern VA and IPS mode LCD with just single retardation film. -
Present research is devoted to the development of optical sheet intended to be used inside LCD Backlight unit in order to improve output axial Luminance. It deals with refractive by nature optical sheet having relief embossed top surface (microlenses array). Patterned reflecting layer can be coated on flat bottom surface.
-
The circuit simulation has been done on the current-programmed AMOLED and shows that the circuit which behaves as a negative capacitance can reduce the effect of parasitic capacitance fixed on the data-line and can accelerate the current programming speed as high as that required in Full HD AMOLED.
-
Chung, Hyun-Joong;Yang, Hui-Won;Kim, Min-Kyu;Jeong, Jong-Han;Ahn, Tae-Kyung;Kim, Kwang-Suk;Kim, Eun-Hyun;Kim, Sung-Ho;Im, Jang-Soon;Choi, Jong-Hyun;Park, Jin-Seong;Jeong, Jae-Kyeong;Mo, Yeon-Gon;Kim, Hye-Dong 1097
We demonstrate that the performance of amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFT) can be optimized by controlling the interfaces between IGZO and sandwiching insulators and by proper deposition of IGZO layer. Specifically, contact and channel resistances are decreased by reducing IGZO bulk resistance and optimizing dry-etch process, respectively. Field-effect mobility ($\mu_{FE}$ ) and subthreshold gate swing (S) are further enhanced by fine-tuning IGZO deposition condition. -
Cho, Doo-Hee;Yang, Shin-Hyuk;Byun, Chun-Won;Lee, Jeong-Ik;Hwang, Chi-Sun;Kopark, Sang-Hee;Chu, Hye-Yong;Cho, Kyoung-Ik 1101
We have fabricated the transparent TFTs using new oxide material (AZTO: Al-doped zinc tin oxide) as an active layer. The AZTO TFT showed good performance without post-annealing. The electrical characteristics were improved by the post-annealing up to$300^{\circ}C$ . The AZTO TFTs exhibited a mobility of$8{\sim}12\;cm^2/Vs$ , a sub-threshold swing of 0.2~0.6 V/dec, and an on/off ratio of more than$10^9$ . -
Staggered type self-aligned transparent-oxide-semiconductor transistors with indium-zinc-oxide as a semiconductor have studied. In this device fabrication, successive sputtering of oxide semiconductor and insulator without breaking of vacuum and without exposing in air, humidity and oxygen can be realized because oxide semiconductor is transparent. As a result of fabrication, transistor characteristics with mobility of
$30cm^2/Vs$ and on-off ratio of$10^5$ could be obtained for the newly developed self-alignment device structure. -
D'Andrade, Brian W.;Esler, James;Lin, Chun;Adamovich, Vadim;Xia, Sean;Weaver, Michael S.;Kwong, Raymond;Brown, Julie J. 1109
High efficacy white OLEDs with low voltage, high quantum efficiency and outcoupling fixtures achieve total power efficacies of 89 lm/W to 102 lm/W, operating voltages between 2.8 V and 3.5 V at correlated color temperatures of 2,800 - 3,900 K and color rendering ~70, at 1,000 nits. -
Lee, Sung-Hun;Kim, Mu-Gyeom;Song, Jung-Bae;Kim, Sang-Yeol;Tamura, Shinichiro;Kang, Sung-Kee;Kim, Jong-Min;Lee, Sung-Soo;Choi, Jun-Ho;Ha, Jae-Kook;Chu, Chang-Woong;Kim, Chi-Woo;Lee, Jin-Seok 1112
A very high current efficiency of 28 cd/A for three-mode microcavity tandem WOLED was successfully demonstrated. The 101 % of NTSCu'v' ratio of this white OLED with LCD color filter was achieved. In addition to wide color gamut, the highest delta (u'v') of respective RGB colors among the viewing angles 0 and 60 degree is just 0.042 and that of white color is less than 0.02. -
We developed phosphorescent white OLEDs with high efficiency and color stability. By engineering device architecture in which confined excitons within the emissive layer by using adequate interlayer and balanced recombination of charge carriers by using stepwise hole transporting layer system, these WOLEDs showed power efficacy of 43.6 lm/W with CRI = 62 and 36 lm/W with CRI = 72 at
$100\;cd/m^2$ without outcoupling enhancements. -
Park, Young-Seo;Kang, Dong-Min;Park, Jong-Won;Kwon, Soon-Ki;Kang, Jae-Wook;Kim, Yun-Hi;Kim, Jang-Joo 1120
Efficient, color stable multi-EML WOLED have been fabricated using newly synthesized yellowish green dopant Ir(chpy)3 or Ir(mchpy)3. The devices have high external quantum efficiency of 11.7%, color rendering index of 87, variation of CIE coordinate of (0.02, 0.01) between 10 to 5000 cd/m2, and low roll-off in efficiency with increasing brightness. -
Integral imaging is a three-dimensional display technique which has 100 years of history. The method is characterized by offering full parallax, almost-continuous viewpoints and easiness of moving picture display. In this paper, the history of the method is briefly explained and overview of its current status is provided.
-
In this invited paper, numerical reconstruction and pattern recognition using integral imaging are overviewed. The computational integral imaging method reconstructs three-dimensional information at arbitrary depth-levels. Photon-counting nonlinear matched filtering combined with the computational reconstruction provides promising results for the application of low-light level recognition.
-
In this paper, it is proposed that the integral imaging technique is applied to reconstruct 3D (three dimensional) objects with enhanced depth of field, computationally and optically. Lens array using birefringence material is adopted to obtain the reconstruction. The elemental images sets are picked up through common micro lens array and utilized to present 3D reconstruction images using adopted lens array.
-
By defining a uniform reference point array corresponding to the 3D voxel array and abandoning voxels whose deviations from their respective reference points exceed a given tolerance, the distribution of voxels within the volumetric 3D image space gets uniform, effects of non-uniform distribution upon the image reconstructing are eased.
-
Present and trend of oxide phosphor thin film development for electroluminescent device applicationsThe present status and trend of oxide phosphor thin-film development for thin-film electroluminescent (TFEL) device application are presented in this paper. Recently, several newly developed types of bendable or bendable see-through oxide TFEL lamps have been fabricated using the TFEL technology with a newly developed bendable ceramic sheet, glass sheet or sapphire sheet substrate, which has become available on the market. Stable operation at high temperatures was obtained in double-insulating-layer-type TFEL lamps fabricated with a
$Zn_2Si_{0.6}Ge_{0.}4O_4$ :Mn thin-film emitting layer forming on translucent or transparent bendable sheet substrates. -
Nitride semiconductor based light-emitting diodes attain a new functionality of polychromatic emission by the use of three-dimensionally faceted microstructures, which may lead to an advanced lighting technology in which the light source spectra are synthesized so as to meet requirements of the application.
-
Color dimming technology has been developed for high color gamut and aggressive power saving. In our new algorithm, we proposed a new concept of 'color class', with which it is possible to control RGB color luminance effectively and exactly. We reached color gamut of 155% of NTSC 1976 and reduced power consumption under 100 watt for 46 inch LCD.
-
Yeo, Dong-Min;Kwon, Yong-Hoon;Kang, Eui-Jeong;Park, Se-Ki;Yang, Byung-Choon;Kim, Gi-Cherl;Jang, Tae-Seok 1156
Local dimming driving has advantages in reducing power consumption and improving contrast ratio(CR). In an LED backlight unit(BLU), many small LED blocks are implemented in 2-dimmensional space, and luminance of the blocks is controlled by a local dimming algorithm. However, such a BLU can induce various recognizable artifacts. A new novel algorithm is proposed for exact block luminance calculation to correct local dimming artifacts. Also we discuss modified low-gray-level dimming to achieve much aggressive power saving in a local dimming BLU system. -
Since Samsung SDI and Sony started mass production of AM-OLED display for mobile/TV applications, OLED technology has emerged as leading candidate among the many technologies under development for next generation Flat panel displays. P-OLED (Polymer Organic Lighting Emitting Diode) technology, a class of OLED, is gathering momentum towards commercialization. P-OLED technology has made tremendous progress in terms of display performance (including life time, efficiency and color gamut) and in the maturity of ink jet printing process and equipment. In order to get into the mobile/TV application market successfully, P-OLED display technology must meet the following display makers' requirements: (1) P-OLED Display Performance in terms of lifetime, efficiency, and color coordinates, (2) Low Cost Manufacturing Technology such as "Solution Processable Printing Technology". P-OLED technology has already overcome many of the hurdles to mass manufacturing. In this paper, the latest developments in ink jet printing technology, including P-OLED material performance, is discussed.
-
For OLED to be a key role in the television market, a manufacturing evaporation system with robustness and high throughput is indispensable. ANS is currently developing manufacturing equipments for OLED TVs. ANS's latest progress of a vertical high throughput in-line evaporation system for large substrate will be presented.
-
We studied the properties of vapor flux distributions of nozzle shaped thermal evaporation sources and the factors, which can change the flux distributions such as nozzle structure. We used a simulation and experiment methods for this study. By using the results of our study, we improved the Circular Nozzle Source, which can make uniform thin films without substrate rotation, into more efficient source.
-
Flat panel display manufacturers are always investigating new techniques to improve productivity and reliability. For fluid dispense processes, Jet dispensing has shown benefits over traditional needle dispensing. Recent advancements in nozzle design and construction techniques enable jet dispensing capabilities far exceeding what has been previously achieved.
-
$GeO_2$ /ormosil organic-inorganic hybrid films doped with neodymium ions and$TiO_2$ /Ormosil organic-inorganic hybrid films dispersed with neodymium oxide nanocrystals are prepared by combining an inverse microemulsion technique and a low-temperature sol-gel technique. The effects of$Nd^{3+}$ concentration,$Nd_2O_3$ nanocrystal content, and heat treatment temperature on up-conversion and photoluminescence luminescence properties of the hybrid films are studied. -
The on-axis luminance gain as well as the viewing-angle characteristics of flat-lamp-based backlights have been analyzed for the first time. The on-axis luminance gain on each optical film in flat-lamp backlight was smaller than that obtained from the conventional tubular-lamp-based backlight. The origin of and possible solution to this problem were suggested.
-
A new mercury-free flat fluorescent lamp with a single cell having dimension 2.2inches across the diagonal, had been developed which shows a wide, stable operating voltage margin, high luminance and luminous efficacy by adopting the bipolar pulse drive scheme. In this paper, the single cell is expanded into a multi-structured configuration to realize a 32inch sized panel across the diagonal by a simple repetition of the single cells. A driving scheme is proposed for a 2-bit areal selective dimming using dual auxiliary electrodes and bipolar drive scheme.
-
We propose a novel light guide plate for an edge-lit LED backlight. Properly designed micro-prisms enable light to go out of the LGP in near vertical direction and luminance fluctuations in front of the LEDs to be invisible.
-
Fortunato, E.;Pereira, L.;Barquinha, P.;Do Rego, A. Botelho;Goncalves, G.;Vila, A.;Morante, J.;Martins, R. 1199
High mobility bottom gate thin film transistors (TFTs) with an amorphous gallium tin zinc oxide (a-GSZO) channel layer have been produced by rf magnetron cosputtering using a gallium zinc oxide (GZO) and tin (Sn) targets. The effect of the post annealing temperatures ($200^{\circ}C$ ,$250^{\circ}C$ and$300^{\circ}C$ ) was evaluated and compared with two series of TFTs produced at room temperature and$150^{\circ}C$ during the channel deposition. From the results it was observed that the effect of pos annealing is crucial for both series of TFTs either for stability as well as for improving the electrical characteristics. The a-GSZO TFTs operate in the enhancement mode (n-type), present a high saturation mobility of$24.6\;cm^2/Vs$ , a subthreshold gate swing voltage of 0.38 V/decade, a turn-on voltage of -0.5 V, a threshold voltage of 4.6 V and an$I_{ON}/I_{OFF}$ ratio of$8{\times}10^7$ , satisfying all the requirements to be used in active-matrix backplane. -
Lee, Je-Hun;Kim, Do-Hyun;Yang, Dong-Ju;Hong, Sun-Young;Yoon, Kap-Soo;Hong, Pil-Soon;Jeong, Chang-Oh;Lee, Woo-Geun;Song, Jin-Ho;Kim, Shi-Yul;Kim, Sang-Soo;Son, Kyoung-Seok;Kim, Tae-Sang;Kwon, Jang-Yeon;Lee, Sang-Yoon 1203
For a large sized, ultra definition (UD) and high refresh rate for motion blur free AMLCD TVs, amorphous IGZO thin film transistor (TFT) are applied and investigated in terms of threshold voltage ($V_{th}$ ) shift influenced by active layer thickness uniformity, source drain etching technology, heat treatment and passivation condition. Optimizing above parameters, we fabricated the world's largest 15 inch XGA AMLCD successfully. -
Fung, Tze-Ching;Chuang, Chiao-Shun;Mullins, Barry G.;Nomura, Kenji;Kamiya, Toshio;Shieh, Han-Ping David;Hosono, Hideo;Kanicki, Jerzy 1208
We study the amorphous In-Ga-Zn-O thin-film transistors (TFTs) properties under monochromatic illumination ($\lambda=420nm$ ) with different intensity. TFT off-state drain current ($I_{DS_off}$ ) was found to increase with the light intensity while field effect mobility ($\mu_{eff}$ ) is almost unchanged; only small change was observed for sub-threshold swing (S). Due to photo-generated charge trapping, a negative threshold voltage ($V_{th}$ ) shift is also observed. The photofield-effect analysis suggests a highly efficient UV photocurrent conversion in a-IGZO TFT. Finally, a-IGZO mid-gap density-of-states (DOS) was extracted and is more than an order lower than reported value for a-Si:H, which can explain a good switching properties of the a-IGZO TFTs. -
We investigate the effect of a light emitting layer (EML) sequence and an interlayer on the performance of the phosphorescent-fluorescent mixed white organic light emitting diodes. Two types of phosphorescent-fluorescent mixed system were evaluated. The proper position of each primary color EML was crucial to obtain best performance in each system whereas the effect of an interlayer was found to be different in both systems.
-
Seo, Ji-Hoon;Kim, Gu-Young;Hyung, Gun-Woo;Lee, Kum-Hee;Kim, You-Hyun;Kim, Woo-Young;Yoon, Seung-Soo;Kim, Young-Kwan 1219
The Authors have demonstrated highly efficient white organic light-emitting diodes using hybrid-spacer which was inserted between each emitting layer or/and codoped blue emitting layers with the different functional material. The characteristics of WOLEDs showed the maximum external quantum efficiency of 13.8%, power efficiency of 33.66 lm/W, and Commission Internationale de I'Eclairage coordinates of (x=0.36, y=0.37), respectively. -
The power efficiency of a full-color OLED display decreases with long-term operation because of the material characteristics. The lifetime of the OLED display also decreases as the power efficiency declines. Therefore, this work provides a novel color difference algorithm to improve the power consumption and extend the OLED lifetime.
-
Someya, Takao;Sekitani, Tsuyoshi;Noguchi, Yoshiaki;Yokota, Tomoyuki;Klauk, Hagen;Zschieschang, Ute 1229
We have successfully manufactured high-quality top-contact organic thin-film transistors using inkjet technologies with sub-femtoliter droplet volume. Silver fine lines were directly patterned by inkjet on pentacene channel layers. The minimum width of silver lines was$1{\mu}m$ with without the need for pre-patterning or surface pretreatments. The mobility was$0.3\;cm^2/Vs$ . -
This study presents the fabrication process and display characteristics of a flexible organic polymer display device that consists of a thin substrate of Polyether Sulfone, a multilayer serpentine-type microheater array that is fabricated on the substrate, and a UV-sensitive polydiacetylene (PDA)-polyvinyl alcohol (PVA) composite film. A retention time of one second is achieved with cell sizes of
$500{\mu}m$ and$700{\mu}m$ with cell-to-cell distances of$100{\mu}m$ and$200{\mu}m$ , respectively. -
Imaging Systems Technology is conducting research and development in large area flexible plasma displays. These displays will be used for low cost dynamic signage and billboards. In this paper, IST will report its current progress in achieving very bright full color displays.
-
Cheng, W.Y.;Chang, Y.P.;Lo, K.L.;Lee, D.W.;Lee, H.H.;Kuo, S.W.;Hsiao, C.C.;Chen, K.T.;Tsai, Y.H.;Chen, Y.C.;Fuh, S.Y.;Wang, C.W.;Su, P.J.;Chiu, W.W.;Lee, K.C.;Shiu, J.W. 1240
The 6- inch electrowetting display (EWD) can be successfully developed by ink jet printing (IJP) technique. Due to the drop-on-demand characteristic of IJP technology, colored oil can be precisely dosed into the unit pixel. Here, we present the active matrix EWD in this article. By adopting this technique to dose different colored oils, single layer Multi-color EWD without adopting color filter can be achieved in the future. -
This presentation highlights work from the authors' laboratories on the various kinds of oxide optical materials, mainly luminescence and pigment materials with different forms (powder, core-shell structures, thin film and patterning) prepared by the Pechini-type sol-gel (PSG) process. The PSG process which uses the common metal salts (nitrates, acetates, chlorides etc) as precursors and citric acid (CA) as chelating ligands of metal ions and polyhydroxy alcohol (such as ethylene glycol or poly ethylene glycol) as cross-linking agent to form a polymeric resin on molecular level, allowing the preparation of many forms of luminescent materials.
-
ZnO:Zn films have been deposited on the glass substrates using thermal vapor deposition method. Different morphologies such as ZnO slice, pillar and nanorod have been derived. The relationship between photoluminescence and morphology has been studied. Photocatalytic activity has been performed to validate that defects play an important role in the photoluminescence process.
-
Song, Jay-Hyok;Song, Yu-Mi;Kim, Ji-Hyun;Kim, Min-Ju;Kim, Ji-Hyun;Kwon, Seon-Young;Park, Do-Hyung;Kim, Yoon-Chang;Zang, Dong-Sik 1255
New phosphors that enable the 3D application of PDP have been developed The decay times of$Y_3Al_5O_{12}:Ce^{3+}$ ,$(Y,Gd)Al_3(BO_3)_4:Tb^{3+}$ and$(Y,Gd)_2O_3:Eu^{3+}$ were extremely shorter than those of conventional PDP phosphors. The color coordinates and intensities of the phosphors were also suitable for PDP For the first time in PDP industry, 3D/2D switchable PDP has been commercially available by adopting the phosphors. -
Laser-based crystallization techniques are ideally-suited for forming high-quality crystalline Si films on active-matrix display backplanes, because the highly-localized energy deposition allows for transformation of the as-deposited a-Si without damaging high-temperature-intolerant glass and plastic substrates. However, certain significant and non-trivial attributes must be satisfied for a particular method and implementation to be considered manufacturing-worthy. The crystallization process step must yield a Si microstructure that permits fabrication of thin-film transistors with sufficient uniformity and performance for the intended application and, the realization and implementation of the method must meet specific requirements of viability, robustness and economy in order to be accepted in mass production environments. In recent years, Low Temperature Polycrystalline Silicon (LTPS) has demonstrated its advantages through successful implementation in the application spaces that include highly-integrated active-matrix liquid-crystal displays (AMLCDs), cost competitive AMLCDs, and most recently, active-matrix organic light-emitting diode displays (AMOLEDs). In the mobile display market segment, LTPS continues to gain market share, as consumers demand mobile devices with higher display performance, longer battery life and reduced form factor. LTPS-based mobile displays have clearly demonstrated significant advantages in this regard. While the benefits of LTPS for mobile phones are well recognized, other mobile electronic applications such as portable multimedia players, tablet computers, ultra-mobile personal computers and notebook computers also stand to benefit from the performance and potential cost advantages offered by LTPS. Recently, significant efforts have been made to enable robust and cost-effective LTPS backplane manufacturing for AMOLED displays. The majority of the technical focus has been placed on ensuring the formation of extremely uniform poly-Si films. Although current commercially available AMOLED displays are aimed primarily at mobile applications, it is expected that continued development of the technology will soon lead to larger display sizes. Since LTPS backplanes are essentially required for AMOLED displays, LTPS manufacturing technology must be ready to scale the high degree of uniformity beyond the small and medium displays sizes. It is imperative for the manufacturers of LTPS crystallization equipment to ensure that the widespread adoption of the technology is not hindered by limitations of performance, uniformity or display size. In our presentation, we plan to present the state of the art in light sources and beam delivery systems used in high-volume manufacturing laser crystallization equipment. We will show that excimer-laser-based crystallization technologies are currently meeting the stringent requirements of AMOLED display fabrication, and are well positioned to meet the future demands for manufacturing these displays as well.
-
TFT-LCD panel makers have been enlarging size of TV screens, and 50-inch TFT-LCD is one of the main stream products already. To have more improved resolution, productivity and lower manufacturing cost, new TFT-LCD factories adopt large mother glass, new TFT structure and new process/materials. Along with these technology evolution, laser repair system should equip with upgraded performance and additional functions on user's demand. Laser repair technology is reviewed and newly developed repair technology is being introduced.
-
Limanov, A.B.;Chung, U.J.;Van Der Wilt, P.C.;Chitu, A.M.;Choi, J.B.;Turk, B.A.;Im, James S. 1267
The two-shot SLS method has recently been successfully implemented in volume manufacturing of advanced LTPS-based LCDs. In this presentation, we discuss how the approach is also well suited for being implemented in high-throughput and high-yield manufacturing of large AMOLED displays on large glass substrates. -
We find some array mura are caused by S/D bridge or channel open in 4 mask process. The gray tone PR thickness non-uniformity is the main reason of these defects. By the adjustment of exposure and dry etch parameters, S/D bridge and channel open ratio drops by 10.87%.
-
Choi, Shin-Il;Kim, Sang-Gab;Choi, Seung-Ha;Kim, Shi-Yul;Kim, Sang-Soo;Lee, Seung-Hun;Kwon, Ho-Cheol;Kim, Gon-Ho 1272
We present the development of dry etch process for the liquid crystal display (LCD) fabrication using a dielectric barrier discharge (DBD) system at atmospheric pressure. In this experimental work, the dry etch characteristics and the electrical properties of thin film transistor are evaluated by using the scanning electron microscopy and electric probe, and TFT-LCD panel ($300\;mm\;{\times}\;400\;mm$ ) is manufactured with the application of the amorphous silicon etch step in the 4 mask and 5 mask processes. -
Organic field effect transistors are excellent candidates for addressing and local amplification elements for large area electronics because they can easily be processed at low temperatures on essentially arbitrary substrates. We present the use of these devices in an active matrix photodetector and as a buffer for a strain sensor.
-
We describe how the phenomenon of dielectric dispersion in nematic liquid crystals influences the director dynamics and thus the switching speed of nematic-based displays.
-
We report on a wide-viewing liquid crystal (LC) display with bi-level microstructures spontaneously formed by selective wetting on a chemically heterogeneous surface. The bi-level microstructures serve as spacers for maintaining uniform cell gap, as well as protrusions for wide-viewing properties. Our LC cell having the bi-level microstructures shows good electro-optic properties.
-
As Flat Panel Display become large in format, the data and gate lines turn into longer, parasitic capacitance and resistance increase, and the display signal is delayed. Three dimensional architecture of multiplexing data registration integrated circuit method is used that divides the data line into several blocks and provides the advantages of high accuracy, rapid selection, and reasonable switching speed.
-
Threshold Voltage Instability in a-Si:H TFTs and the Implications for Flexible Displays and CircuitsAllee, D.R.;Venugopal, S.M.;Shringarpure, R.;Kaftanoglu, K.;Uppili, S.G.;Clark, L.T.;Vogt, B.;Bawolek, E.J. 1297
Electrical stress degradation of low temperature, amorphous silicon thin film transistors is reviewed, and the implications for various types of flexible circuitry including active matrix backplanes, integrated drivers and general purpose digital circuitry are examined. A circuit modeling tool that enables the prediction of complex circuit degradation is presented. -
In this study, we used a multiple phase scheme for the clock in the dual-pull-down driver for TFT display panels. In this scheme, the turn-on time for the transistors in the dual-pull-down structure was reduced from 1/2 to 1/4 or 1/8 of the period cycle time. While keeping proper operation of the transistor size of circuit was fine tuned to achieve an optimal performance. The relation between the active time and the transistor dimensions was obtained for the optimal design.
-
In this study, we redesigned the reliable integrated on-panel display gate driver that was equipped with dual pull-down as well as controlled discharge-path structure to reduce the high voltage stress effect and realized with TSMC 0.35 um CMOS-based technology before. An improved discharge path and a low noise design are proposed for our new a-Si TFT process implementation. Our novel reliable gate driver design can make each cell of shift register to be insensitive to the coupling noise of that stage.
-
We have developed new electrical dopants of rhenium oxide (
$ReO_3$ ) and cupper iodide (CuI) as p-dopants and rubidium carbonate ($Rb_2CO_3$ ) as an n-dopant, respectively.$ReO_3$ has advantage of low temperature evaporation (about$300^{\circ}C$ ) with enhanced device stability. Various kinds of high performance organic light emitting diodes have been realized, including bottom emission, tandem, and top-emission OLEDs. -
Birnstock, Jan;Werner, Ansgar;Blochwitz-Nimoth, Jan;Canzler, Tobias;Murano, Sven;Huang, Qiang;Lux, Andrea 1315
It is well-known that PIN technology is beneficial for numerous OLED applications, e.g. active and passive matrix displays, lighting and signage. Furthermore, it can be used for other organic electronic applications such as OTFTs and organic solar cells. Here, the state of the art of the PIN technology and the latest results from the different application fields are presented. -
Lee, Jun-Yeob;Yook, Kyoung-Soo;Jeon, Soon-Ok;Joo, Chul-Woong;Lee, Tae-Woo;Noh, Tae-Yong;Yang, Haa-Jin;Kang, Sung-Kee 1319
$CsN_3$ was developed as a novel n doping material with air stability and low deposition temperature. Evaporation temperature of$CsN_3$ was similar to that of common hole injection material and it worked well as a n dopant in electron transport layer. Driving voltage was lowered and high power efficiency was obtained in green phosphorescent devices by using$CsN_3$ as a dopant in electron transport layer. It could also be used as a charge generation layer in combination with$MoO_3$ . In addition, n doping mechanism study revealed that$CsN_3$ is decomposed into Cs and$N_2$ during evaporation. This is the first work reporting air stable and low temperature evaporable n dopant in organic light-emitting diodes. -
Development of Plasma Damage Free Sputtering Process for ITO Anode Formation Inverted Structure OLEDLee, You-Jong;Jang, Jin-N.;Yang, Ie-Hong;Kim, Joo-Hyung;Kwon, Soon-Nam;Hong, Mun-Pyo;Kim, Dae-C.;Oh, Koung-S.;Yoo, Suk-Jae;Lee, Bon-J. 1323
We developed the Hyper-thermal Neutral Beam (HNB) sputtering process as a plasma damage free process for ITO top anode deposition on inverted Top emission OLED (ITOLED). For examining the effect of the HNB sputtering system, Inverted Bottom emission OLEDs (IBOLED) with ITO top anode electrode were fabricated; the characteristics of IBOLED using HNB sputtering process shows significant suppression of plasma induced damage. -
A novel fiber optic solution is provided to efficiently mix visible colors. Full color synthesis was achieved utilizing a novel
$3{\times}1$ hard polymer clad fiber (HPCF) coupler along with red, green and blue (RGB) light emitting diode (LED) primaries. Varying the intensities of RGB LEDs that are coupled to three input ports, the device rendered a full color with an ultra wide CIE color gamut. Potential applications in pica-projection displays and LED backlights will be discussed. -
In this paper, we developed a novel hyperreality display called the Head Dome Projector (HDP). The HDP is a head-mounted display consisting of a dome-shaped screen with a very small radius of 40 cm, a mobile projector with ultra-wide projection lens and LED light sources. The main feature of the HDP is very wide viewing angle of 160 degrees horizontally by 120 degrees vertically comparable to the human visual field of view without head tracking and 360 degrees by 360 degrees with head tracking. According to our subjective evaluation comparing the HDP with a flat-panel display (FPD), the HDP realizes hyperreality 2.5 points higher than that realized by an FPD in the case of
${\pm}5$ level evaluation for HD motion images. -
A compact diode-pumped microchip(DPM) green light source which consist of pump LD,
$Nd:YVO_4$ , KTP and a built-in thermoelectric element has been fabricated for laser projection display. The volume of the source is as small as$0.7\;cm^3$ and we obtained the output power of 25mW with the average electric power consumption in pump LD of 304mW which correspond to the electrical-to-optical efficiency of 7.8%. Another approach using quasi phase matching(QPM) technique has been attempted. We obtained the output power of 90mW of green beam with 350mW pumping of a$Nd:YVO_4$ laser with 20-kHz rep. rate and 10-ns pulse duration. Detailed characteristics and issues of the DPM and QPM green light sources will be addressed. -
Since 2006, the Industrial Technology Research Institute and the University of Cincinnati have been jointly exploring approaches for high brightness flexible electrowetting displays (EWDs). Recently, ITRI demonstrated for the
$1^{st}$ time a 6" AM-EWD reflective display panel. To create flexible AM-EWDs, Cincinnati has developed low-temperature processing and improved pixel structures. -
$KSrPO_4$ and$Sr_3(Al_2O_5)Cl_2$ phosphors doped with$Eu^{2+}$ emit a blue and orange-yellow luminescence under ultraviolet (UV) excitation at ~ 400 nm, respectivel, which can be used for making white light emitting diodes. -
The efficacy and its degradation of light emitting diode(LED) are related to its PN junction's temperature(Tj). Currently efficacy in certain temperature and thermo-resistant are defined for the depending. However, the definitions are quite inconvenient for lighting application. The paper focuses on the issue and presents a method to evaluate the thermal characteristics of LED efficay.
-
The applications of white LEDs has been expanded from mobile phone to LCD TV as a backlight source recently and now are penetrating into the lighting market. With these changes new requirements for LEDs phosphors are demanded. In this point of view recent technology trend of phosphors for LCD backlight and lighting will be discussed.
-
Research on down conversion phosphor materials is the key for the development of solid state lighting (SSL). Especially finding alternative red phosphor for white LEDs based on blue or NUV LEDs are important research task. Under this view, we have synthesized a series of
$Eu^{3+}$ substituted$La_2W_{2-x}Mo_xO_9$ (x = 0 ~ 2, insteps of 0.1) red phosphor and characterized by X-ray diffraction (XRD) and photoluminescence. XRD results reveal a phase transition from triclinic to cubic structure for$x\;{\geq}\;0$ . All the compositions show broad charge transfer band due to charge transfer from oxygen to tungsten/molybdenum and red emission due to$Eu^{3+}$ ions. Select compositions show high red emission intensity compared to the commercial red phosphor under NUV/blue ray excitation. Hence, this candidate can be possible red emitting phosphors for white LEDs. -
Reflection measurements are critical to the evaluation of display performance under ambient illumination conditions. Various hemispherical reflection methods are evaluated for their suitability and robustness across display technologies. The standard integrating sphere method is compared to a sampling sphere apparatus.
-
Several different techniques currently exist for measuring display view angle performance. These include conoscopes, goniometric systems, and, most recently introduced to the market, instruments based on Imaging Sphere technology. This paper will compare measurement accuracy and speed of these various methodologies with different FPD types and even 3-D displays.
-
Narutaki, Yozo;Sakai, Eiji;Shimizu, Shinji;Tsuda, Keisuke;Uehara, Masao;Uehara, Toshinori;Katoh, Shinsuke;Yoda, Yuji 1362
ED-2523 (Measuring methods for matr ix reflective LCD modules) was published by JEITA (Japan Electronics and Information Technology Industries Association) in 2001. Since then, round robin tests had been done and the accuracy of measurement values had been discussed. In this paper, considerations for error factors in four measurement systems are showed. -
We introduce new instrument that provides the spectral radiance at any incidence and azimuth angle in all the visible range. LCD emission and transmittance properties of display components can be measured precisely at each incidence and azimuth angle and wavelength. Full polarization spectral analysis can be also made.
-
This paper introduces a novel display measuring instrument that allows accurate, spectro-radiometric measurement of the complete viewing cone while the measuring time is similar to that of a CCD camera with transform lens optics. Actually the new instrument, named POLYGONIOSCOPE, is orders of magnitude faster compared to a conventional spot spectrometer.
-
A development of low power display is an important problem from a point of reduction in worldwide energy consumption. In this research, we aimed to achieve a high quality and low power paper-like reflective full-color display and investigated the design rules for the light diffusing film, LC-cell structure, front lighting systems based on the diffused light control technology. As a result, we successfully obtained the high quality reflective liquid crystal display with a high reflectivity, a wide color gamut and a high motion picture quality.
-
Cholesteric Blue phase (ChBP) is constructed by the regular arrangement of the double helix, whereas the Smectic Blue phase (SmBP) has the inter-connected multi-lamellar structure. Orientation fluctuations of polymer stabilized ChBP and spontaneously super-cooled SmBP are discussed. Spatial topology of the defects play key role on the dynamic properties.
-
In the viewing-angle image control (VIC) technology, one pixel is made up of a quad pixel structure which is consisting of R, G, B, and electrically control briefringence (ECB) sub-pixels. Two types of test stimuli were used; text & complex image respectively. The limitations of those methods were found from the experiment. From the results the advanced GC technology was proposed.
-
Viewing Angle Switching using Hybrid Aligned Nematic Liquid Crystal Display Driven by a Fringe-FieldChin, Mi-Hyung;Jeong, Eun;Lim, Young-Jin;Kim, Jin-Ho;Srivastava, Anoop Kumar;Lee, Seung-Hee 1386
Conventional viewing angle switching electrode requires pixel division and additional liquid crystal panel. Hence the conventional viewing angle switching has low aperture ratio and high thickness. In this paper we proposed new viewing angle switching using hybrid aligned nematic mode by fringe-field electrode field (named HAN-FFS) with single liquid crystal panel. The fringe-field switching electrode is located at the bottom, and the additional common electrode is located at the top of the cell to control viewing angle. The proposed device is free from additional liquid crystal panel and pixel division. Consequently, the suggested structure has not only high aperture ratio but also show an excellent potential for viewing angle switching. -
Image quality is one of the most important factors affecting the performance of digital displays. This paper introduces various digital image processing techniques commonly applied to digital displays. They include preferred color correction, tone reproduction, and frame rate conversion. Also, issues related to image quality evaluation are addressed.
-
Lim, Kyoung-Won;Kim, Han-Soo;Noh, Hyun-Chul;Shin, Hyun-Chul;Jung, Woo-Chul;Koo, Gun-Jae;Park, Ryuk 1397
Frame rate conversion became key technology due to recent advances in LCD panel refresh rates. Although many FRC algorithms have been developed and applied for LCD TV sets, they still suffer from well-known halo artifact. This paper discusses about the artifacts and method to handle them. -
Temperature Compensation Method of Local Dimming LED Backlight System is proposed. The luminance levels of the LED backlight are not stable over temperature and time due to the inherent characteristics of the LED. The characteristics of LED backlight are investigated and a temperature compensation method is presented. The image distortion caused by temperature variation of LED block can be effectively compensated by the proposed temperature compensation method.
-
Synchronization signal circuit system for low cross-talk stereoscopic display. We proposed the employment of the scanning beams of any adjacent scanning regions gradually scan from upper to down direction of the LED backlight panel.
-
We developed
$Sn^{4+}$ -porphyrin complexes that show thermally activated delayed fluorescence (TADF). TADF intensities increased with an increase of temperature because of an acceleration of the reverse intersystem crossing from triplet to singlet excited states by heat activation. TADF component provides a novel pathway for high efficiency OLEDs. -
Using a
$Ir(ppy)_3$ doped in the TCTA:$Bepp_2$ mixed host and N- and P-doped in TCTA:$Bepp_2$ charge transport layers, an ideal energy level alignment technology is developed. A very low roll-off current efficiency of 7.4 % at a luminance of$10,000\;cd/m^2$ with this technology is demonstrated in green phosphorescent OLEDs. -
In this paper, the light emitting efficiency, spectrum, and the lifetime of the phosphorescent devices, whose emission characteristics are strongly dominated not only by the energy transfer but also by the charge carrier trapping induced by the emissive dopant, are explained by differences in the energy levels of the host, dopant, and nearby transport layers. On the basis of our finding on device performance and photocurrent measurement data by time-of-flight (TOF), we investigated the effect of the difference of carrier trapping dopant and properties of the host materials on the efficiency roll-off of phosphorescent organic light emitting diode (OLED), along with a physical interpretation and practical design scheme, such as a multiple host system, for improving the efficiency and lifetime of devices.
-
Sexton, Ian;Bates, Richard;Lee, Wing;Surman, Phil;Hopf, Klaus;Neumann, Frank;Corbett, Alex;Buckley, Edward 1423
This paper describes current work regarding two EC funded projects, MUTED and HELIUM3D whose objective is to produce an autostereoscopic display system which is well suited to domestic television applications. Both of these projects have common roots in a previous EC funded project (ATTEST) and both employ laser illumination and viewer head tracking. -
In this paper, an illumination system design using two lamps was proposed to improve the brightness of the projector. The proposal is based on the results from optical simulation. The prism array was applied to maintain the same optical properties, such as brightness distribution for the divergence angle and the composed beam size of the system. These were compared to those of the one UHP lamp system. The brightness of the two-lamp system, having a panel size of 0.74" and an f/2.9, increased by a factor of 1.7 when compared to the brightness of one UHP lamp system.
-
We have developed a high-contrast ambient-light rejection projection screen with surface micro-structures for front and rear projection displays with an oblique-angle projector. We have fabricated prototype screens that show a better than
$10{\times}$ improvement in contrast compared to a matte-white screen under various ambient lighting conditions and screen luminance. -
LED has gained its importance in the projection display market from very compact, micro-projectors to potentially high output, desktop systems. In both of these systems, the output levels are less than desirable. This paper describes practical recycling and multiplexing systems that provide brightness increases, and allow projectors to achieve outputs beyond its current levels.
-
Kim, Chul-Hong;Chae, So-Ra;Lee, Min-Hee;Jeong, Hyun-Mi;Kim, Beom-Kwon;Heo, Eun-Gi;Choe, Deok-Hyeon;Lee, Byung-Hak 1437
In this paper, we mainly deal with metallic electrode materials and patterning processing of plasma display panels. We focus on the recent development status, where low cost and high performance electrode materials such as Ag-based single-layered bus, low cost-in-use and anti-migration address electrodes are briefly introduced. The technological trends and further works on novel electrode materials and processing are also discussed. -
Takaba, Hiromitsu;Serizawa, Kazumi;Onuma, Hiroaki;Kikuchi, Hiromi;Suzuki, Ai;Sahnoun, Riadh;Koyama, Michihisa;Tsuboi, Hideyuki;Hatakeyama, Nozomu;Endou, Akira;Carpio, Carlos A. Del;Kubo, Momoji;Kajiyama, Hiroshi;Miyamoto, Akira 1441
We developed ultra-accelerated quantum chemical molecular dynamics and spectroscopic characterization simulators for development of PDP materials. By combination of these simulators, realistic structure of PDP materials is drawn on the computer. Furthermore, based on the structures, various properties such as cathode luminescence spectrum and secondary electron emission, is successfully evaluated. The strategy of "Experiment integrated Computational Chemistry" using developed simulators will presented that has the potential in being powerful tool for designing the PDP materials. -
Micro crystal structure of polycrystalline MgO film is controlled by adjusting the energy of particles arrived at the substrate during deposition. The change of crystal structure affects on the total area of (200) surface where the oxygen vacancies are formed easily, resulting in the change of secondary electron emission (SEE) coefficient(
$\gamma$ ). -
Riva, Mauro;Bonucci, Antonio;Tominetti, Stefano;Carretti, Corrado;Han, Yong-Gyu;Hong, Sung-Hee;Choi, Eun-Ha 1448
In this paper we investigate, on the basis of experimental data, the correlations between contamination issues occurring during production process steps and final PDP operational parameters: these reciprocal relations are the result of dynamic equilibria established within the PDP system, amongst residual gases and sorbed species interacting with heat, ions and photons. -
Amorphous silicon (a-Si:H) thin-film transistors (TFTs) are fabricated on flexible organic polymer foil substrates. As-fabricated performance, electrical bias-stability at elevated temperatures, electrical response under mechanical flexing, and prolonged mechanical stability of the TFTs are studied. TFTs made on plastic at ultra low process temperatures of
$150^{\circ}C$ show initial electrical performance like TFTs made on glass but large gate-bias stress instability. An abnormal saturation of the instability against operation temperature is observed. -
O'Rourke, Shawn M.;Loy, Douglas E.;Moyer, Curt;Bawolek, Edward J.;Ageno, Scott K.;O'Brien, Barry P.;Marrs, Michael;Bottesch, Dirk;Dailey, Jeff;Naujokaitis, Rob;Kaminski, Jann P.;Allee, David R.;Venugopal, Sameer M.;Haq, Jesmin;Colaneri, Nicholas;Raupp, Gregory B. 1459
In this paper we describe solutions to address critical challenges in direct fabrication of amorphous silicon thin film transistor (TFTs) arrays for active matrix flexible displays. For all flexible substrates a manufacturable handling protocol in automated display-scale equipment is required. For metal foil substrates the principal challenges are planarization and electrical isolation, and management of stress (CTE mismatch) during TFT fabrication. For plastic substrates the principal challenge is dimensional instability management. -
We report all-ink-jet printed inorganic/organic hybrid TFTs on plastic substrates. We have investigated the optimal printing conditions to make uniform patterned layers of gate electrode, dielectrics, source/drain electrodes, and semiconductor as a coplanar type TFT in a successive manner. All ink-jet printed devices have good mechanical flexibility and current modulation characteristic even when bent.
-
Hwang, Chi-Sun;Kopark, Sang-Hee;Byun, Chun-Won;Ryu, Min-Ki;Yang, Shin-Hyuk;Lee, Jeong-Ik;Chung, Sung-Mook;Kim, Gi-Heon;Kang, Seung-Youl;Chu, Hye-Yong 1466
We have fabricated 2.5 inch QQCIF AM-OLED panel driven by ZnO-TFT on a plastic substrate for the first time. The number of photo mask for the whole panel process was 5 and the TFT structure was top gate with active protection layer as a first gate insulator. Optimizing the process for the substrate buffer layer, active layer, ZnO protection layer, and gate insulator was key factor to achieve the TFT performance enough to drive OLED. The ZnO TFT has mobility of$5.4\;cm^2/V.s$ , turn on voltage of -6.8 V, sub-threshold swing of 0.39 V/decade, and on/off ratio of$1.7{\times}10^9$ . Although whole process temperature is below$150^{\circ}C$ to be suitable for the plastic substrate, performance of ZnO TFT was comparable to that fabricated at higher temperature on the glass. -
Kobayashi, Shunsuke;Kineri, Tohru;Takatoh, Kohki;Akimoto, Mitsuhiro;Hoshi, Hajime;Nishida, Naoto;Toshima, Naoki;Sano, Satoru 1473
Doping the nanoparticles of Pd, p-$BaTiO_3$ ,$SiO_2$ and MgO into LCs alters their physical properties such as$K_{ii}$ ,$\Delta\varepsilon$ ,${\Delta}n$ ,$\gamma_1$ and$T_{NI}$ . Except for$K_{33}$ , all these parameters decreases and thus bring the reduction of operating voltage and/or response times. -
We report the first TTF compounds having columnar LC phase at room temperature. Based on the thermal, structural, and morphological observations, it was concluded that TTF derivative with long alkyl chains has highly ordered oblique columnar LC at room temperature. The new TTF derivatives have excellent oxidative stability which is desirable for a p-type (hole transport) materials.
-
How one can see that a nematic is indeed biaxial ? I consider some macroscopic effects in the basic biaxial cells and present results of the recent observation of the macroscopic biaxiality in the bent-core mesogens "C7" and "C12" [1,2].
-
Dhayagude, Tushar;Dilip, S;Santo, Hendrik;Vi, Kien;Chen, Sean;Kim, Min-Jong;Schindler, Matt;Ghoman, Ran 1487
mSilica developed a scalable integrated circuit solution for driving multiple arrays of LEDs to backlight TFT-LCD panels. The drivers incorporate adaptive power control of the DC-DC power supply powering the LEDs to improve the efficiency while synchronizing PWM dimming with video timing signals VSYNC and HSYNC to reduce motion blur. -
Typically internal mobile LCD display modules are connected to the mobile product baseband PCB with flexible printed circuit board equipped with board-to-board connector. This solution has a drawback of limiting the product concept work to certain solutions that are based on connector size, location, flexible PCB length, bending, etc. in the display module. Also flexible printed circuit board based solutions are not completely optimized from reliability point of view, causing flex circuit board breakings. For the external displays in the PC or Home entertainment market, the cable solution is too expensive and resource demanding. The wireless solution has obvious advantages over reliability, low cost and flexibility. This paper describes a wireless audio-visual interface solution.
-
We proposed driving method with variable integration time for ambient light sensing. One operation period of the proposed driving method consists of several sub-integration periods with variable integration time which can enlarge dynamic range of ambient light sensing circuit. Temperature dependent characteristic of p-intrinsic-metal (p-i-m) diode can be compensated using the proposed driving method.
-
This paper proposes an efficient data compression for the conventional method of reducing EMI in a 10 bit LCD timing controller (TCON). In addition, we develop a new method to reduce EMI in a LCD TCON through repeated data on adjacent blocks. The novel technique reduced EMI by 10 dB for a 52" FHD 10it LCD TV.
-
A novel white-LED (light emitting diode) backlight system for 46"LCD TVs which involves the current controlled X-Y channel driving method is proposed in this paper. There are two problems related to the LED current in the conventional X-Y channel driving driven by a constant voltage source. To solve these problems, a real time current sensing system is applied to the conventional one and the time-division current sensing method is employed.
-
Monomer and aggregate of
$Bebq_2$ give fluorescence at 492 and 511 nm at 12 K, respectively. Intense T1 emission with vibronic structure was observed from$Bebq_2$ and$Alq_3$ below 70 K by heavily doping with phosphorescent$Ir(ppy)_3$ . Energy transfer from$Ir(ppy)_3$ was clarified by photoluminescence excitation spectra. -
High efficiency phosphorescent organic light emitting devices (
$PHOLED^{TM}s$ ) are now widely used in commercial displays. In this paper we describe some of the work behind the development of high efficiency stable green PHOLEDs capable of fulfilling display specifications. -
We report extremely low doping technology in phosphorescent organic light emitting diodes(PHOLEDs). Highly efficient red PHOLEDs with excellent energy transfer characteristics even under 1 % doping condition have been demonstrated. Results reveal efficient host-dopant system to realize highly efficient PHOLEDs and useful cost saving way by reduction of expensive Ir complex dopants.
-
There are several ways to demonstrate white organic light emitting diodes (OLEDs) for displays and solid state lighting applications. Among these approaches are the stacked three primary or two complementary colors light-emitting layers, multiple-doped emissive layer, and excimer and exciplex emission [1-10]. We report on white phosphorescent excimer devices by using two light emitting materials based on platinum complexes. These devices showed a peak EQE of 15.7%, with an EQE of 14.5% (17 lm/W) at
$500\;cd/m^2$ , and a noticeable improvement in both the CIE coordinates (0.381, 0.401) and CRI (81). Devices with the structure ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 12% FPt (10 nm) /26 mCPy: 2% Pt-4 (15 nm)/BCP (40 nm)/CsF/Al [device 1], ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 2% Pt-4 (15 nm)/26 mCPy: 12% FPt (10 nm)/BCP (40 nm)/CsF/Al [device 2], and ITO/PEDOT:PSS/TCTA (30 nm)/26 mCPy: 2% Pt-4: 12% FPt (25 nm)/BCP (40 nm)/CsF/Al [device 3] were fabricated. In these cases, the emissive layer was either the double-layer of 26 mCPy:12% FPt and 15 nm 26 mCPy: 2% Pt-4, or the single layer of 26mCPy with simultaneous doping of Pt-4 and FPt. Device characterization indicates that the CIE coordinates/CRI of device 2 were (0.341, 0.394)/75, (0.295, 0.365)/70 at 5 V and 7 V, respectively. Significant change in EL spectra with the drive voltage was observed for device 2 indicating a shift in the carrier recombination zone, while relatively stable EL spectra was observed for device 1. This indicates a better charge trapping in Pt-4 doped layers [10]. On the other hand, device 3 having a single light-emitting layer (doped simultaneously) emitted a board spectrum combining emission from the Pt-4 monomer and FPt excimer. Moreover, excellent color stability independent of the drive voltage was observed in this case. The CIE coordinates/CRI at 4 V ($40\;cd/m^2$ ) and 7 V ($7100\;cd/m^2$ ) were (0.441, 0.421)/83 and (0.440, 0.427)/81, respectively. A balance in the EL spectra can be further obtained by lowering the doping ratio of FPt. In this regard, devices with FPt concentration of 8% (denoted as device 4) were fabricated and characterized. A shift in the CIE coordinates of device 4 from (0.441, 0.421) to (0.382, 0.401) was observed due to an increase in the emission intensity ratio of Pt-4 monomer to FPt excimer. It is worth noting that the CRI values remained above 80 for such device structure. Moreover, a noticeable stability in the EL spectra with respect to changing bias voltage was measured indicating a uniform region for exciton formation. A summary of device characteristics for all cases discussed above is shown in table 1. The forward light output in each case is approximately$500\;cd/m^2$ . Other parameters listed are driving voltage (Bias), current density (J), external quantum efficiency (EQE), power efficiency (P.E.), luminous efficiency (cd/A), and CIE coordinates. To conclude, a highly efficient white phosphorescent excimer-based OLEDs made with two light-emitting platinum complexes and having a simple structure showed improved EL characteristics and color properties. The EQE of these devices at$500\;cd/m^2$ is 14.5% with a corresponding power efficiency of 17 lm/W, CIE coordinates of (0.382, 0.401), and CRI of 81. -
Uemura, Sashiro;Yotani, Junko;Nagasako, Takeshi;Kurachi, Hiroyuki;Nakao, Takehiro;Ito, Masaaki;Sakurai, Akira;Shimoda, Hideo;Ezaki, Tomotaka;Fukuda, Kazuhiko;Saito, Yahachi 1525
High-luminance CNT-FED character-displays using simple line-rib-structure was performed. One display-panel had$48{\times}480$ -dots and the sub-pixel pitch was 1mm. Another panel had$32{\times}256$ -color-pixels, and the subpixel size was$0.6mm{\times}1.8mm$ . The power consumption was less than 10W at character-displaying module. It should be useful for public display even under emergent no-power condition. -
Since the discovery over a decade ago, carbon nanotubes (CNTs) have been attracting considerable attentions both from scientists and engineers. Because of the excellent field emission properties, such as high aspect ratio, extremely small diameter, and high emission current, CNTs become a potential candidate as field emitter for field emission display (FED) and lighting (FEL) as backlight for LCD. Due to the exceptional physical properties, such as superior thermal and electrical conductivities, as well as high stiffness and strength, the CNT-based composites can be as light-weight heat-sink or thermal spreader materials used for power electronic devices, such as power LED for general illumination. The CNTs for above applications will be reviewed, and related materials and devices will be demonstrated in this paper.
-
Aquesous carbon nanotubes (CNTs) solutions were prepared using SDS (sodium dodecyl sulfonate) and NADDBS (sodium dodecylbenzene sulfonate). Our inks are found to have the viscosity of 1-2 cps. In addition, the surface tension of inks inversely decreased with increasing surfactant concentration and then saturated at critical micelle concentration (CMC). The low surface tension at CMC gave rise to lower contact angles on Indium layers, resulting in larger printable feature sizes. In the fabrication of cold cathode, jet-printing is feasible to modify and scale up the cathode structures. These feasibilities could contribute jet-printing method to be more adaptable for making large-area cold cathodes.
-
Lim, Han-Eol;Ryu, Je-Hwang;Lim, Joon-Won;Son, Byoung-Taek;Lee, Yi-Sang;Jang, Jin;Park, Kyu-Chang 1535
Carbon nanotube arrays were fabricated using micro molding in capillary (MIMIC) process. Patterns remained on the surface in the pattern complementary to that present in the mold. CNTs were selectively grown on the MIMIC patterned sites with a triode PECVD. And turn on field for$10\;{\mu}A/cm^2$ electron emission current was$2.2\;V/{\mu}m$ turn on field. -
The field degradation of carbon nanotube field emitters in diode emission at constant current was demonstrated to be highly dependent upon the presence of residual gases at partial pressures. Upon exposure to a higher pressure of oxygen containing gases, for example,
$O_2$ and CO increased the voltage. Those gases give rise to chemical etching to CNTs emitters. On the contrary,$CH_4$ affected the emission properties in the opposite direction as decreasing the voltage which was probably attributed to the introduction of adsorbate tunneling states. The mixed gas may cause a combined effect of both adsorbate tunneling states and CNT etching. -
Modified pulse waveforms were applied to an AC plasma display panel with an auxiliary electrode in order to improve the operation voltage margin. Reciprocal sustain pulse waveforms and modified auxiliary pulse waveforms were applied to the sustain and auxiliary electrode, respectively. During the sustain period, the influence of the address electrode on the luminous efficacy of long-coplanar gap discharges was mitigated by application of reciprocal sustain pulse waveforms. Modified auxiliary pulse waveforms maintained the high efficacy obtained from the AC PDP with an auxiliary electrode. The proposed reciprocal sustain and modified auxiliary pulses waveforms can induce stable discharges in long-coplanar gap discharges and can control wall charges with a wider auxiliary pulse voltage margin, thereby enhancing the luminous efficacy of the AC PDP with an auxiliary electrode.
-
Choi, Kwang-Yeol;Min, Woong-Kee;Rhee, Byung-Joon;Ahn, Byung-Nam;Kim, Je-Seok;Moon, Won-Seok;Park, Min-Soo;Ryu, Byung-Gil;Kim, Sung-Tae;Ahn, Young-Joon;Yang, Sung-Soo;Kim, Kyung-Tae;Lee, Kyu-Sung 1547
We are suggesting a new index to represent the performance of PDP, such as Specific Performance Index (SPI) that includes luminous efficacy and panel reflectance. High Xe gas mixture and low panel capacitance are well known as key factors to improve luminous efficacy of PDP [1]. However, higher driving voltage and longer discharge time lag is an obstacle when applying these technologies. Modified cell design, new materials and driving waveform enable us to overcome these obstacles. High efficient phosphor is also a key material to improve luminous efficacy. Phosphors coated with pigment are used to reduce panel reflectance. High performance 50-inch HD PDP with luminous efficacy of 2.3 lm/W has been developed. -
In this paper, some important driving issues pertaining to the sustain-driving circuit are examined A new driving circuit is also proposed The new circuit is cost effective and has a simple PCB layout in comparison to the conventional one. Some additional driving advantages are noted as well.
-
Baik, Bong-Joo;Choi, Kwang-Yeol;Min, Wong-Kee;Hong, Mun-Heon;Lee, Dong-Woo;Min, Byung-Kuk;Kim, Weo-Dong 1555
Various approaches were undertaken by major PDP makers in order to improve the luminous efficacy of the plasma discharge cells. There have been many reports that state that using a high Xe content PDP is one of the most promising key technologies available to improve the luminous efficacy. In the case of the higher Xe content panel, the higher address and sustain voltage were needed to drive the panel under the same reset condition. In this study, a variety of Xe content panels were investigated in order to examine wall voltage transfer behaviors. The transferred wall voltage status after addressing discharge at the same driving condition was analyzed by comparing Vt close curve of high and low Xe content panels. Through this analysis of Vt close curve difference, the driving waveform of a high Xe panel was quantitatively adjusted Under the same address voltage condition, results showed that the amount of the transferred wall voltage and Vt close curve after addressing discharge was matched for the first sustain discharge. Taking these results into consideration, we conclude that the driving waveform for different Xe content panels could be designed for the desired addressing discharge condition and the wall voltage state of the cell could be quantitatively controlled and measured through these approaches. -
We report an optical second harmonic generation measurement that allows direct probing of dynamical carrier motion in organic field effect transistors. Carrier injection and transport process are discriminated. The mobility and contact resistance of pentacene FETs are determined from the visualized diffusion-like carrier motion.
-
We demonstrate here a self-aligned printing approach that allows downscaling of printed organic thin-film transistors to channel lengths of 100 - 400 nm. A perfected down-scaled polymer transistors (L= 200 nm) showing high transition frequency over 1.5 Mhz were realized with thin polymer dielectrics, controlling contact resistance, and minimizing overlap capacitance via self-aligned gate configuration.
-
In this paper, fabrication of a
$60{\times}48$ polymer TFT array with a top-gate structure on plastic substrates using a low temperature printing process will be presented and the device structure and manufacturing processes will be discussed. The polymer TFT array showed excellent air stability and uniform electrical characteristics over a large area. Finally, a 1.5 inch EPD display with 50 dpi resolution using the polymer TFT array will be demonstrated for e-film device applications. -
A simulation system is developed to calculate the apparent motion-induced image from a sequence of temporal luminance transitions, while using the properties of the human visual system. Based on the simulation method, both edge (moving block) and detail degradation (line spreading, grating, sinusoidal pattern), and also color aberration are discussed.
-
A mixture of two different types of polyimide, one having an alkyl side chain and ordinarily used for homeotropic alignment, and the other without a side chain and ordinarily used for planar alignment, is deposited and baked at high temperatures. When the resulting cell is filled with a nematic liquid crystal, it is found that the pretilt angle is a function of the baking temperature or mixing ratio, and can be controlled continuously over the range 0 to 90.
-
We propose an optical configuration for a vertical alignment (VA) liquid crystal (LC) cell to eliminate the off-axis light leakage in the dark state. The proposed compensation configuration consists of a positive A-film, a positive C-film and a negative C-film. The optical design is performed on a Poincar
$\acute{e}$ sphere. This configuration has a better tolerance to the wavelength dispersion, as the polarization trace could self-compensate it. From calculations, we show that the proposed VA LC cell can improve the viewing angle characteristics by compensating for the light leakage in the diagonal direction. -
We proposed a technique controlling continuously pretilt angle in full range with high process margin. The proposed method is characterized by tuning thickness of heterogeneous polyimide (PI) layer that homeotropic PI is mixed with planar PIs.
-
The tubular field emission lamp (FEL) was developed using a wire type carbon-nano-structure emitter called CNX The luminous efficiency of the tubular FEL (diode type, diameter:
${\varphi}15.5mm$ , length: 200mm) has already achieved around 45lm/W and we expect to achieve over 60lm/W within the year. -
Carbon nanotube (CNT) cathodes were fabricated using nano-sized silver powders as a bonding material. The effects of powder size on the field emission properties for the CNT cathode were investigated The better emission properties of CNT cathodes using smaller particles are due to a low sintering temperature of the bonding materials.
-
We describe the fabrication of transparent conducting single-walled carbon nanotubes (SWCNTs) film on flexible substrate following the conventional spin coating method. The fabricated film was post treated with diluted acid solution and its electrical and optical characterizations were performed. The electrical conductivity of SWCNTs film was enhanced and the film was found to be attached strongly with substrate after the post treatment.
-
We considered most general electron emission caused by temperature as well as electric field with a free electron gas model. The total electron emission current density comes from field emission effect where electron energy is lower than vacuum and from thermionic emission effect where electron energy is higher than vacuum. The total electron emission current density is shown as a function of temperature for constant electric field, and as a function of electric field for constant temperature.
-
In this paper, we present a novel process for the realization of large area, low cost field emission cathodes. The process makes use of alumina substrates, which are anodically oxidized in order to yield porous structures capable of hosting metal catalyst nanoparticles. By carefully controlling the final stage of the anodisation as well as the electrodeposition conditions, it is possible to fine tune the density of such catalysts in the range of
$10^8-10^9/cm^2$ . The catalytic growth of CNTs is subsequently performed at low temperature (${\sim}\;600^{\circ}C$ or below, thanks to the use of$H_2O$ ), using plasma enhanced chemical vapour deposition. There is no lithography need to make the cathode and current densities of${\sim}\;1mA/cm^2$ are easily obtained. -
Hiroshima University opened the advanced display laboratory (ADL) in 2006 to specifically focus on the PDP researches. The mission of ADL is to lay the bases for the innovative PDP technologies. Our research efforts have been concentrated on the fundamental study of protective materials and phosphors, and also of the effect of protective materials with high
$\gamma$ emission in the high luminous efficacy. This paper briefly introduces the present status of our research activities. -
Park, Choon-Sang;Jang, Soo-Kwan;Kim, Jae-Hyun;Tae, Heung-Sik;Jung, Eun-Young;Ahn, Jung-Chull;Heo, Eun-Gi 1617
The effects of the temporal and permanent bright image stickings were examined under variable panel working gas pressure in the 42-in. ac-PDP with a high Xe (11 %) content. In the cells with and without temporal and permanent bright image stickings, the display luminance, firing voltage, and Vt closed curve were measured relative to the working gas pressure. With a decrease in the working gas pressure, the temporal bright image sticking was observed to be reduced, whereas the permanent bright image sticking was observed to be deteriorated. -
Transparent ac-PDP test panel was prepared via a combination of materials including ITO sustaining electrodes, thin film dielectric layer and nano-sized phosphor powders. The thin film dielectric layer was prepared by E-beam evaporation process and phosphor layer was deposited on metal mesh pattern by electrophoretic deposition process. The optical transmittance and luminance of the panel indicated that full color transparent ac-PDP is feasible with the approach.
-
Yagi, I.;Hirai, N.;Miyamoto, Y.;Noda, M.;Imaoka, A.;Yasuda, R.;Yoneya, N.;Nomoto, K.;Yumoto, A.;Kasahara, J. 1627
We have demonstrated a flexible and full-color OTFT-OLED display. The display has a top-emitting pixel structure with a resolution of 80 ppi, which can be achieved by developed integration architecture of OTFTs. The 0.3-mm-thick flexible display exhibits peak brightness over 100 nit with a contrast ratio greater than 1000:1. -
Koo, Bon-Won;Kim, Do-Hwan;Moon, Hyun-Sik;Kim, Jung-Woo;Jung, Eun-Jeong;Kim, Joo-Young;Jin, Yong-Wan;Lee, Sang-Yun;Kim, Jong-Min 1631
We demonstrate 4-in QVGA active-matrix electrophoretic display based on ink-jet printed organic transistors on glass substrates. Our TFT array had a bottom-gate, bottom-contact device architecture. The organic semiconductor and gate dielectric were solution processed. The field-effect mobility of the printed devices, calculated in the saturation region, was$0.1{\sim}0.3cm^2/Vs$ at Vg=-20 V. -
We will discuss encapsulation of OLEDs on both flexible and rigid glass substrates. Accelerated testing at 6CC/90RH and 85C/85RH is compared and acceleration factors for OLED and Calcium test samples are discussed.We have tested the stability and performance of our barrier coating to much higher temperatures: up to 140 C. Water Vapor Transmission rates at temperatures from 60 to 140 C are presented. Rates and methods for low cost manufacturing on a large scale are analysed.
-
We have investigated the effectiveness of a gravure printing method for the fabrication of organic light-emitting diode (OLED) and Organic Thin Film Transistor (OTFT). Printing of the organic layers was performed with a small-scale gravure coating machine, while the metallic layers were vacuum-evaporated. Devices with gravure-printed layers are at least comparable with the spin-coated devices. Effects of the solvent formulation and surface energy mismatch between the organic layer materials on the printed patterns and device performance were discussed. We will present the initial design and experimental data of OTFT fabricated by roll-type soft contact transfer process.
-
Ong, Hiap L.;Liang, Justin;Guo, Jia Haw;Chen, I Hao;Wu, Chang Lin;Lan, Wei-Chou;Lin, Tung-Liang 1645
We successfully fabricated lowest-cost superior perform ance MVA LCDs with highest-yield, high transmission, high contrast-ratio, and wide viewing angle. Using the amplified intrinsic fringe field (AIFF) controlled MVA invented by Ong, we eliminated all protrusions and ITO slit geometries. We further achieved: (1) faster gray-gray response times without the over-drive technology, (2) faster tough mura, and (3) lower flicker and cross-talk in the row inversion driving schemes. -
A novel configured S-IPS LCD has been developed introducing a new compensation film with an anti-reflective layer. This new technology provides wide viewing characteristics as well as excellent visibility under bright indoor lighting or natural lighting.
-
A new high contrast LCD structure for TN mode TFT-LCD, of which the contrast ratio is 1.2 times hi gher than that of the conventional one, has been developed. The contrast ratio of TFT-LCD display can be improved by some modified materials, which like as polarizer, liquid crystal, color filter and light enhancement film. In order to know which condition can get the major contribution for the upgrade of the contrast ratio, we used Taguchi method and analyzed the contribution ratio for each composition and succeed to build up the formula of contrast ratio. From this study, we could achieve the highest CR value as 1200:1 of TN mod e TFT-LCD nowadays.
-
Jang, Won-Gun;Beom, Tae-Won;Cui, Hao;Park, Jong-Rak;Hwang, Seong-Jin;Lim, Young-Jin;Lee, Seung-Hee 1656
The reflective type color filter for the liquid crystal displays (LCD) was produced using cholesteric liquid crystal monomers whose phase is characterized by the unique optical features of selective reflection. Periodic micrometer scale hemi-spherical photoresist (PR) patterns were formed on glass substrates by thermal reflow method after photolithography. Cholesteric color filter films for red, green and blue light reflections were then produced and the viewing angle dependence was investigated and compared with that of reflected light on the non-patterned substrates.