• 한국전기전자재료학회논문지
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• 제15권2호
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• pp.110-118
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• 2002

Organic thin film transitors(OTFT) are of interest for use in broad area electronic applications. And recently organic electroluminescent devices(OELD) have been intensively investigated for using in full-color flat-panel display. We have fabricated inverted-staggered structure OTFTs at lower temperature using the fused-ring polycyclic aromatic hydrocarbon pentacene as the active eletronic material and photoacryl as the organic gate insulator. The field effect mobility is 0.039∼0.17 ㎠/Vs, on-off current ratio is 10$\^$6/, and threshold voltage is -7V. And here we report the study of driving emitting, Ir(ppy)$_3$, phosphorescent OELD with all organic thin film transistor and investigated its electrical characteristics. The OELD with a structure of ITO/TPD/8% Ir(ooy)$_3$ doped in BCP/BCP/Alq$_3$/Li:Al/Al and OTFT with a structure of inverted-stagged Al(gate electrode)/photoacry(gate insulator)/pentacene(p-type organic semiconductor)/ Au(source-drain electrode) were fabricated on the ITP patterned glass substrate. The electrical characteristics are turn-on voltage of -10V, and maximum luminance of about 90 cd/㎡. Device characteristics were quite different with that of only OELD.

• 한국재료학회지
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• 제19권8호
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• pp.417-420
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• 2009

This study develops a highly transparent ohmic contact using phosphorus doped ZnO with current spreading for p-GaN to increase the optical output power of nitride-based light-emitting diodes (LEDs). The phosphorus doped ZnO transparent ohmic contact layer was prepared by radio frequency magnetron sputtering with post-deposition annealing. The transmittance of the phosphorus doped ZnO exceeds 90% in the region of 440 nm to 500 nm. The specific contact resistance of the phosphorus doped ZnO on p-GaN was determined to be $7.82{\times}10^{-3}{\Omega}{\cdot}cm^2$ after annealing at $700^{\circ}C$. GaN LED chips with dimensions of $300\times300{\mu}m$ fabricated with the phosphorus doped ZnO transparent ohmic contact were developed and produced a 2.7 V increase in forward voltage under a nominal forward current of 20 mA compared to GaN LED with Ni/Au Ohmic contact. However, the output power increased by 25% at the injection current of 20 mA compared to GaN LED with the Ni/Au contact scheme.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.431-431
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• 2013

Flexible Organic Light Emitting Diode (OLED) displays are required for future devices. It is possible that plastic substrates are instead of glass substrates. But the plastic substrates are permeable to moisture and oxygen. This weak point can cause the degradation of fabricated flexible devices; therefore, encapsulation process for flexible substrate is needed to protect organic devices from moisture and oxygen. Y.G. Lee et al.(2009) [1] reported organic and inorganic multilayer structure as an encapsulation barrier for enhanced reliability and life-time.Flowable Oxide process is a low-temperature process which shows the excellent gap-fill characteristics and high deposition rate. Besides, planarization is expected by covering dust smoothly on the substrate surface. So, in this research, Bi-layer structured is used for encapsulation: Flowable Oxide Thin film by PECVD process and Al2O3 thin film by ALD process. The samples were analyzed by water vapor transmission rate (WVTR) using the Calcium test and film cross section images were obtained by FE-SEM.

• 조명전기설비학회논문지
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• 제24권5호
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• pp.1-7
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• 2010

광원으로써 다양한 장점을 가지고 있는 LED 소자는 응용 분야의 확대가 빠르게 진행되고 있다. 특히 조명 분야의 LED 응용은 더욱 활발하다. 본 논문에서는 비교적 낮은 광량이 요구되는 옥내 외 문자표시용 광원, 양면 발광형 광원, 저휘도 LED BLU 분야에 적합하도록 투명 Plate와 LED 칩을 조합하여 광원을 구현하였다. 투명광원 구현을 위해 폴리카보네이트 계열의 plate 사용하였으며 LED 칩의 구동을 위한 구리회로를 plate 표면에 형성하였다. 또한 기존 패키지를 사용하던 LED 광원 대신 투명 plate 표면에 LED 칩을 직접 장착하는 기술을 적용하였다. 최종 제품은 다수개의 광원 모듈을 결합하여 BLU또는 면광원에 적합한 샘플을 제작하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1140-1143
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• 2009

Organic Vapor Phase Deposition (OVPD) equipment enables the accurate and simultaneous control of deposition rates of multiple materials as well as their homogenous mixing in the gas phase. Graded or even cross-faded layers by varying carrier gas flow are options to improve OLED performances. As example, we will show how the efficacies of standard red phosphorescent OLEDs with sharp interfaces can be increased from 18.8 cd/A and 14.1 lm/W (1,000 cd/$m^2$) to 36.5 cd/A (+94 %, 18 % EQE) and 33.7 lm/W (+139 %) by the introduction of cross-fading, which is a controlled composition variation in the organic film.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.62-65
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• 2007

Conventional semiconductor processes have been utilized to fabricate 3.5-inch OTFT-driven OLEDs with a resolution of $176\;{\times}\;144$ pixels on plastic substrates. By using a PC-OVD method to deposit a pentacene layer and optimizing patterning and the following processes, we could complete a uniform and reliable integration procedure for an active matrix organic light emitting devices on a plastic substrate. The technical importance of ours is the applicability of conventional semiconductor process to organic materials on plastic substrates. Although there are many hurdles to overcome, our approach and technical improvements are proved to be applicable to plastic electronics.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.212-216
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• 1997

A new metal tip fabrication process for low voltage operation is reported in this paper. The key element of the fabrication process is that isotropic silicon etching and oxidation process used in silicon tip fabrication is utilized for gate hole size reduction and gate oxide layer. A metal FEA with 625 tips was fabricated in order to demonstrate the validity of the new process and submicron gate apertures were successfully obtained from originally 1.7$\mu\textrm{m}$ diameter mask. The emission current above noise level was observed at the gate bias of 50V. The required gate voltage to obtain the anode current of 0.1${\mu}\textrm{A}$/tip was 74V and the emission current was stable above 2${\mu}\textrm{A}$/tip without any disruption. The local field conversion factor and the emitting area were calculated as 7.981${\times}$10\ulcornercm\ulcorner and 3.2${\times}$10\ulcorner$\textrm{cm}^2$/tip, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.317-320
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• 1998

Electroluminescent(EL) devices based on organic materials have been of great interest due to their possible applications for large-area flat-panel displays, where they are attractive because of their capability of multicolor emission, and low operation voltage. In this study, glass substrate/ITO/Eu(TTA)$_3$(Phen)/Al(A), glass substrate/ITO/TPD/Eu(TTA)$_3$(phen)/Al(B) aNd glass substrate/ITO/TPD/Eu(TTA)$_3$(Phen)/A1Q$_3$/Al (C) structures were fabricated by vacuum evaporation method, where aromatic diamine(TPD) was used as a hole transporting material, Eu(TTA)$_3$(phen) as an emitting material, and tris(8-hydroxyquinoline) Aluminum (AlQ$_3$) as an electron transporting layer. Etectroluminescent(EL) and I-V characteristics of Eu(TTA)$_3$(phen) with a various thickness were investigated. This structure shows the red EL spectrum, which is almost the same as the PL spectrum of Eu(TTA)$_3$(phen). I-V characteristics of this structure show that turn-on voltage was 9V and current density was 0.01A/㎤ at a dc operation voltage of 9V. Electrical transporting phenomena of these structures was explained using the trapped-charge-limited current model with I-V characteristics.

• Transactions on Electrical and Electronic Materials
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• 제16권3호
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• pp.162-167
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• 2015

To investigate the effect of fluoro groups substitution on poly(p-phenylenevinylene) derivatives, poly(2,3,5,6- tetrafluoro-p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCTF-PPV, and poly[2,3,5,6-tetrafluoro-p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], PMTF-PPV, were synthesized by the well-known Wittig condensation polymerization process. To compare the influences of fluoro groups, no fluoro groups containing model polymers, poly(p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCPPPV and poly[p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], p-PMEH-PPV, were also synthesized. The resulting polymers were completely soluble in common organic solvents and exhibited good thermal stability up to 300℃. The polymers showed UV-visible absorbance and photoluminescence (PL) in the ranges of 259~452 nm and 500~580 nm, respectively. The tetrafluorophenyl containing PCTF-PPV and PMTF-PPV showed relatively red-shifted PL peaks at 521 nm and 580 nm, respectively, compared to that of non-fluoro groups containing polymers (PCP-PPV: 500 nm and p-PMEH-PPV: 539 nm). The single-layer light-emitting diode was fabricated in a configuration of ITO/polymer/Al. Electroluminescene (EL) emissions of PCP-PPV, PCTF-PPV, p-PMEH-PPV and PMTF-PPV were shown at 507, 524, 556, and 616 nm, respectively.

• 반도체디스플레이기술학회지
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• 제18권3호
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• pp.100-104
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• 2019

We have investigated the feasibility of fabricating fine stripes using needle coating for potential applications in solution-processed organic light-emitting diodes (OLEDs). To this end, we have employed an aqueous poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) solution that has been widely used as a hole injection layer (HIL) of OLEDs and performed needle coatings by varying the process parameters such as the coating gap and coating speed. As expected, the stripe width is reduced with increasing coating speed. However, the central thickness of the stripe is rather increased as the coating speed increases, which is different from other coating processes such as slot-die and blade coatings. It is due to the fact that the meniscus formed between the needle tip and the substrate varies depending sensitively on the coating speed. It is also found that the stripe width and thickness are reduced with increasing coating gap. To demonstrate its applicability to OLEDs, we have fabricated a red OLED stripe and obtained light emission with the width of about 90㎛.