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Issue
Korean Chemical Engineering Research,
Vol.51, No.5, 634-639, 2013
저일함수 금속 아세트산 화합물 층을 사용한 유기발광다이오드의 전기발광 특성 향상
Effects of Low Workfunction Metal Acetate Layers on the Electroluminescent Characteristics of Organic Light-Emitting Diodes
김만수, 류근채, 김영철
유기발광다이오드(Organic Light-Emitting Diodes, OLEDs)의 효율을 향상시키기 위하여 다양한 아세트산금속(Macetate, M: Li, Na, K, Cs)을 cathode underlayer 소재로 사용하고 이들이 소자의 전자주입 및 발광 특성에 미치는 영향에 대하여 연구하였다. 1 nm 두께의 M-acetate 층을 cathode underlayer로 사용한 경우 Cs-acetate를 사용한 소자를 제외한 모든 소자에서 기존의 LiF 전자주입층을 사용한 소자보다 효율적인 전자주입 및 향상된 발광특성을 보였으며, M-acetate에 포함된 금속의 일함수가 작을수록 높은 전류밀도와 우수한 발광특성을 보였다. 또한, cathode underlayer 의 두께가 소자의 특성에 미치는 영향을 분석한 결과, 사용된 M-acetate의 분자크기에 따라 각기 다른 두께(Li-acetate 0.7 nm, Cs-acetate 2.0 nm)에서 최적의 발광특성을 보였으며 기존의 LiF 층을 사용한 소자에 비하여 동일 인가전압에서 전류효율이 약 60% 향상된 결과를 얻을 수 있었다.
We investigated the effects of a cathode underlayer on the electroluminescence (EL) characteristics of organic light-emitting diodes (OLEDs) using various metal acetates (M-acetate, M = Li, Na, K, Cs) as a cathode underlayer. When 1 nm thick M-acetate layers were used as a cathode underlayer, the OLEDs with M-acetate showed better EL performance than the device with the conventional LiF electron injection layer except the device with Cs-acetate. More enhanced current density and improved EL characteristics were obtained when lower work function metal acetate was employed. In addition, the optimum M-acetate layer thickness that gives the best device performance proved to be 0.7 and 2.0 nm for Li-acetate and Cs-acetate, respectively, probably depending on the molecular size of M-acetate. The OLEDs with the M-acetate layers of optimized thickness demonstrated more than 60% enhanced current efficiency compared with that of the device using an LiF layer at the same applied voltage.
Keywords: OLED; Cathode Underlayer; Work Function; Metal Acetate; Electron Injection
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참고문헌정보(참고문헌, 인용문헌)는 화학공학소재연구정보센터에 의해 제공되고 있습니다.