Buffer Layers to Enhance Light Outcoupling for Organic Light-Emitting Diodes

이호년,조현준 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.-

Outcoupling enhancement methods for organic light-emitting diodes (OLEDs) have been studied using anode and cathode buffers. The outcoupling of OLEDs is enhanced by using thin, high-refractive-index anode buffers,such as 25-nm and 50-nm tungsten-oxide layers and 15-nm titanium-oxide layers. Thick or low-refractiveindex anode buffers reduce outcoupling. OLEDs with 1-nm and 1.5-nm magnesium-fluoride cathode buffers have higher outcoupling than do OLEDs with 0.5-nm cathode buffers. Thin, high-refractive-index anode buffers enhance the extraction of light from the waveguide modes of the anode. As the anode buffer thickness increases,additional waveguide modes form in the anode buffer layer itself and the outcoupling is reduced. Therefore,the thickness of the anode buffer layer should be optimized within a range that does not generate additional bound modes.

알루미늄 도핑된 산화아연 양극을 적용한 고효율 유기발광다이오드

이호년,이영구,정종국,이성의,오태식,Lee, Ho-Nyeon,Lee, Young-Gu,Jung, Jong-Guk,Lee, Seung-Eui,Oh, Tae-Sik 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.8

Properties of organic light-emitting diodes (OLEDs) with aluminum-doped zinc oxide (ZnO:Al) anodes showed different behaviors from OLEDs with indium tin oxide (ITO) anodes according to driving conditions. OLEDs with ITO anodes gave higher current density and luminance in lower voltage region and better EL and power efficiency under lower current density conditions, However, OLEDs with ZnO:Al anodes gave higher current density and luminance in higher voltage region over about 8V and better EL and power efficiency under higher current density over $200mA/cm^2$. These seemed to be due to the differences in conduction properties of semiconducting ZnO:Al and metallic ITO. OLEDs with ZnO:Al anodes showed nearly saturated efficiency under high current driving conditions compared with those of OLEDs with ITO anodes. This meant better charge balance in OLEDs with ZnO:Al anodes. These properties of OLEDs with ZnO:Al anodes are useful in making bright display devices with efficiency.

Organic passivation layers for pentacene organic thin-film transistors

이호년,이영구,Ik Hwan Ko,Eok Chai Hwang,Sung Kee Kang 한국물리학회 2008 Current Applied Physics Vol.8 No.5

We studied the passivation layers for pentacene organic thin-film transistors (OTFTs) that were used to drive the active-matrix organic-light-emitting-diodes (AMOLEDs) fabricated by inkjet process. Conventional polyvinyl acetate (PVA) passivation layer could not protect OTFT channel from poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) inkjet process so that the performance was degraded critically after the process. By applying PVA/PVA/photoacryl (PA) multi-passivation layers, we could get OTFT arrays with We studied the passivation layers for pentacene organic thin-film transistors (OTFTs) that were used to drive the active-matrix organic-light-emitting-diodes (AMOLEDs) fabricated by inkjet process. Conventional polyvinyl acetate (PVA) passivation layer could not protect OTFT channel from poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) inkjet process so that the performance was degraded critically after the process. By applying PVA/PVA/photoacryl (PA) multi-passivation layers, we could get OTFT arrays with

산화물 박막트랜지스터의 연구동향 및 디스플레이 응용

이호년,김성태 에스케이텔레콤 (주) 2008 Telecommunications Review Vol.18 No.6

산화물이 반도체 특성을 지니는 것으로 보고된 이후, 다결정을 지니는 ZnO와 비정질 구조를 지니는 InGaZnO와 ZnSnO 등을 중심으로 연구가 활발히 진행되고 있다. 산화물 TFT는 구조에 따라 각기 다른 장점 및 단점을 지니기 때문에, 사용하고자 하는 목적에 따라 적합한 구조를 지니는 소자를 개발하는 것이 중요하다. 그리고 산화물 트랜지스터는 제조공정 진행 중의 가스 분위기, 노출된 플라즈마로부터의 Damage에 따라 특성의 변화가 매우 심하므로, 적절한 특성 확보를 위해서는 후속 열처리 등을 통하여 특성 변화를 최소화하는 것이 매우 중요하다. 이러한 공정조건 및 구조의 최적화를 통하여, 1 ~ 100 cm2/V•s 정도의 높은 이동도와 대면적에서 균일성을 지니는 산화물 TFT를 제조할 수 있다. 따라서 산화물 반도체는 향후 액정 디스플레이, 전자종이, 유기발광 디스플레이, 투명 디스플레이 및 플렉시블 디스플레이의 기판으로 적용 가능성이 매우 높다고 판단된다.

Dependence of Light-Emitting and Photovoltaic Properties of Dual-Function Organic Diodes on Carrier-Transporting Layers

이호년,최문순 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.-

Dual-function photovoltaic organic light-emitting diodes (PVOEDs) have been investigated in this work. The PVOLEDs emit light when forward biased and generate electricity when backward biased. This dual function is based on the half-gap junction composed of 5,6,11,12-tetraphenylnaphthacene (rubrene) and C60. The device structure was optimized through experiments using various organic materials for the electron-transporting layer (ETL) and electron-injection layer (EIL). Through this work, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), C60 and LiF were selected as the ETL, electron-accepting layer and EIL, respectively. Using this device structure, we obtained a current efficiency of 0.27 cd/A for the light-emitting mode and a powerconversion efficiency of 1.95% for the photovoltaic mode.

Seed를 이용한 일방향응고 Ti-46A1-1.5Mo-0.2C 합금의 크리프 특성

李鎬年,丁仁洙,吳明勳,山口正治,韋當文 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.1

Creep properties of directionally solidified Ti-46A1-1.5Mo-0.2C alloys with well aligned lamellar microstructure have been dramatically improved. The ingots were manufactured by seeding technique directional solidification. Directionally solidified Ti-46A1-1.5Mo-0.2C alloys showed excellent creep properties. However, the creep resistance decreased as the angle between lamellar orientation and loading axis increased. It is found that the control of the lamellar orientation is most important to improve the creep resistance of TiAI alloys. In the results of TEM analysis of creep specimen before and after creep test, it was found that no carbides were formed before creep test. But, after creep test, carbides were formed in γ lath, γ / γ interfaces, γ / α_2 interfaces and dislocations. In the case of creep test at 750℃, the quantity of carbides found in dislocations decreased as the load level increased. It was thought that superior thermal stability of Ti-46A1-1.5Mo-0.2C alloy suppressed the dynamic recrystallization and the coarsening of the lamellar microstructure, and the excellent creep resistance was maintained for long time due to this thermal stability.

층상조직 TiAl 합금의 열적 안정성에 미치는 Si 첨가효과

이호년,김성웅,오명훈,山口正治,위당문 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.11

Thermal stability of Si-doped TiAl alloys with the lamellar microstructure was investigated by partial melting in an optical floating zone(FZ) furnace to ascertain the possibility of usage as a seed material. The lamellar stability of TiAl and TiAl-X(X=Mo, Nb, W) alloys, which proved to be thermally unstable, was improved dramatically by Si addition. In the results of partial melting, it was found that there are two boundaries of Al content(low Al limit and high Al limit) which devide stable and unstable compositions. It is thought that when Al content is lower than low Al limit, recrystallization can be occurred by β-phase formation at high temperature, and when Al content is higher than high Al limit, the lamellar stability will be deteriorated by rapid variation of α/γ phase volume fraction during heating and cooling. The lamellar stability of TiAl-Si alloys can be predicted by drawing above two boundaries at TiAl-Si isothermal section. Moreover, the lamellar stability of TiAl-X-Si alloys can be also predicted by converting the compositions to TiAl-Si compositions. In addition, lamellar orientation control was successfully performed by directional solidification using the Ti-46Al-l.5Mo-1Si alloy as a seed material.

Passivation Layers for Organic Thin-film-transistors

이호년,이영구,Ik-Hwan Ko,Sung-Kee Kang,Seong-Eui Lee,오태식 한국전기전자재료학회 2007 Transactions on Electrical and Electronic Material Vol.8 No.1

Inorganic layers, such as SiOxNy and SiOx deposited using plasma sublimation method, were tested as passivation layer for organic thin-film-transistors (OTFTs). OTFTs with bottom-gate and bottom-contact structure were fabricated using pentacene as organic semiconductor and an organic gate insulator. SiOxNy layer gave little change in characteristics of OTFTs, but SiOx layer degraded the performance of OTFTs severely. Inferior barrier properties related to its lower film density, higher water vapor transmission rate (WVTR) and damage due to process environment of oxygen of SiOx film could explain these results. Polyurea and polyvinyl acetates (PVA) were tested as organic passivation layers also. PVA showed good properties as a buffer layer to reduce the damage come from the vacuum deposition process of upper passivation layers. From these results, a multilayer structure with upper SiOxNy film and lower PVA film is expected to be a superior passivation layer for OTFTs.

산화물 반도체의 특성 및 디스플레이 응용

이호년,김홍규,김성태,Lee, Ho-Nyeon,Kim, Hong-Gyu,Kim, Seong-Tae 한국정보디스플레이학회 2008 인포메이션 디스플레이 Vol.9 No.1

심해자원 생산용 해양플랜트 시스템 및 핵심기자재

이호년 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6