• 마이크로전자및패키징학회지
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• 제23권1호
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• pp.11-15
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• 2016

유기발광다이오드(orgianic light emitting diodes, OLEDs)는 대형 유연 디스플레이와 발광원으로서 사물인터넷 (IoT)의 하드웨어 기기 등 다양한 분야에서 연구가 진행되고 있다. 그러나 낮은 일함수의 금속 및 쉽게 반응하는 유기재료 자체의 특성으로 인하여 외부환경에 매우 취약한 단점을 가지고 있으며 특히, 수분과 산소에 민감하여 외부와의 접촉 시 성능이 급속도로 저하되는 현상을 나타내게 된다. 이를 방지하기 위해 PVD, CVD, ALD 와 같은 방법으로 보호막 형성 연구를 진행 중에 있지만 복잡한 공정 및 높은 비용의 문제점 등이 있다. 그러므로 외부 환경에 의한 성능 저하를 차단해주는 저렴하고 단순한 공정의 페시베이션(passivation) 박막 기술 개발이 매우 중요하다. 본 연구에서는 유기발광다이오드의 수명 향상을 위하여 스핀코팅(spin-coating) 방법으로 녹색 유기발광다이오드 소자 위에 조성비에 따른 페시베이션 박막을 형성한 후 녹색 유기발광다이오드의 휘도특성 변화를 조사하였다. 페시베이션 용액은 poly vinyl alcohol (PVA)를 기반으로 sodium alginate (SA)를 0, 10, 20, 40 wt%의 조성비로 제조하였으며, 40 wt%의 조성비에서 가장 좋은 배리어 보호 특성을 나타내었다. 최종적으로 PVA + SA 용액의 최적화된 페시베이션 보호막을 제작할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.947-950
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• 2001

We report the characteristics of organic light emitting diodes (OLEDS) by controlling the carrier mobility according to the crystalline of Iron(II) Phthalocyanine(Fe-Pc) and metal-free Phthalocyanine (H$_2$-Pc). In order to change the recombination zone, we controlled the hole mobility by changing the crystal structures of Fe-Pc and H$_2$-Pc. OLEDs were constructed with ITO/Fe-Pc/triphenyl-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (Alq$_3$)/Al and ITO/H$_2$-Pc/triphenyl-diamine (TPD)/tris-(8-hydroxyquinoline)aluminum (Alq$_3$)/Al. The electroluminescent properties were changed according to the heat-treatments of Fe-Pc and H$_2$-Pc. We observed that the recombination zone and the carrier mobility were changed as the higher occupied molecular orbital levels of Fe-Pc and H$_2$-Pc decreased.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.901-902
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• 2003

Three-color organic light-emitting diodes (OLEDs) of metal-semiconductor-metal (MSM) structure have been favricated by using m-MTDATA [4,4',4"-tris (3-methylphenylphenylamino) triphenylamine] as hole injection layer(HIL). The mMTDATA is shown to be an effective hole injecting material, in that the insertion of mMTDATA greatly reduces the roughness of anode surface and improves the device performance. Red, green and blue OLEDs were fabricated, and their color coordinates in CIE chromaticity were found to be (0.600, 0.389), (0.240, 0.525), and (0.171, 0.171), respectively. The luminous efficiencies of the fabricated OLEDs were 1.4 lm/W at 106 $cd/m^{2}$ for red, 1.4 lm/W at 100 $cd/m^{2}$ for green, and 2.0 lm/W at 104 $cd/m^{2}$ for blue.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.710-713
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• 2002

In order to improve the power efficiency of multi-layer organic light emitting diodes (OLEDs), electron injection into ETL(electron transport layer) from cathode at the interface between ETL and cathode was enhanced by interposing a proper electron injection layer at the interface. The HTL(hole transport layer) and ETL materials used were N, N'diphenyl- N, N' - bis(3-methylphenyl-1, 1'- biphenyl - 4, 4 'diamine (TPD) and tris (8-hydroxyquinoline) aluminum ($Alq_3$) respectively. Cathodes using co-evaporated Al-CsF, Al-KF, and Al-NaF composites are adopted to enhance the electrical and optical properties of OLEDs. OLEDs with alkaline metal-doped cathode show a luminance of as high as 35,000 cd/$m^2$, and external quantum efficiency about 1.35 %. In addition, they show higher power efficiency at all bias conditions and good reproducibility.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.533-534
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• 2005

Temperature-dependent current-voltage characteristics of organic light-emitting diodes(OLEDs) were studied in a device structure of ITO/TPD/$Alq_3$/Al. The OLEDs were based on the molecular compounds, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-l,1'-diphenyl-4,4'-diamine(TPD) as a hole transport and tris(8-hydroxyquinoline) aluminum($Alq_3$) as an electron transport and emissive material. The current-voltage characteristics were measured in the temperature range of 10K and 300K. We analyzed an electrical conduction mechanism of the OLEDs using space-charge-limited current(SCLC) and Fowler-Nordheim tunneling.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.314-315
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• 2008

We have studied a property change of organic light-emitting diodes (OLED)s due to a surface reformation of indium-tin-oxide(ITO) substrate. An ITO is widely used as a transparent electrode in light-emitting diodes, and the OLEDs device performance is sensitive to the surface properties of the ITO. The ITO surface reformation could reduce the Schottky barrier at the ITO/organic interface and increase the adhesion of the organic layer onto the electrode. We have studied the characteristics of OLEDs with a treatment by a wet processing of the ITO substrate. The self-assembled monolayer(SAM) was used for wet processing. The characteristics of OLEDs were improved by SAM treatment of an ITO in this work. The OLEDs with a structure of ITO/TPD(50nm)/$Alq_3$(70nm)/LiF(0.5nm)/Al(100nm) were fabricated, and the surface properties of ITO were investigated by using seneral characterization techniques. Self-assembled monolayer introduced at the anode/organic interface gave an improvement in turn-on voltage, luminance and external quantum efficiency compared to the device without the SAM layer. SAM-treatment time of the ITO substrate was made to be 0/10/15/20/25min. The current efficiency of the device with 15min. treated SAM layer was increased by 3 times and the external quantum efficiency by 2.6 times.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.416-419
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• 2008

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.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.28-31
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• 2003

We have investigated the electrical characteristics of the organic light emitting diodes (OLEDs) using the numerical device simulation. The current-voltage characteristics, the charge carrier concentrations, and the recombination rate profiles are presented. The simulation results of the effects of the various device parameters on the device characteristics are discussed.

• 소성∙가공
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• 제14권9호통권81호
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• pp.731-740
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• 2005

• Transactions on Electrical and Electronic Materials
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• 제9권1호
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• pp.20-23
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• 2008

Organic light-emitting diodes (OLEDs) are attractive because of possible application in display with low-operating voltage, low-power consumption, self-emission and capability of multicolor emission by the selection of emissive materials. To investigated the optical effects, we studied the electrical and optical characteristics due to thickness variation of electron injection materials LiF on organic light-emitting diodes in the ITO (indium-tin-oxide)/N,N'-diphenyl-N, N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline) aluminum $(Alq_3)/LiF$ layer/Al device. We maintained the thicknesses of TPD and $Alq_3$ layers at 40 nm and 60 nm, respectively. The deposition rates of TPD and $Alq_3$ were in the $1.5{\AA}/s$ under a base pressure of $5{\times}10^{-6}$ Torr. It was found that luminance and luminous efficiency of the device with 0.7 nm LiF layer improve 25 times and 7 times than the device without the LiF layer, respectively.