Multiscale-architected Device Laboratory

nterfacial doping in organic semiconductors (OSs) is an important technique to achieve efficient organic electronic devices. In this paper, we discuss how the charge injection into an OS can be enhan ced by the insertion of a thin interfacial layer or an electrically do ped OS layer between an electrode and an undoped OS. We present that t he vacuum level shift and Fermi level modification by the electrical doping is the origin of the efficient charge injection through a metalorganic junction and an organicorganic junction. Applicatio n to organic electronics such as organic light-emitting diodes (OLEDs )and organic photovoltaics (OPVs) is briefly summarized.

The effect of electrical doping on the hole carrier mobility in a p-doped organic semiconductor is reported. We focus on the ohmic current region where the density of carriers generated by doping is much higher than that of injected carriers. We can therefore ana lyze the effect of doping on the charge-carrier mobility, excluding t he effect of the injected charge-carrier density and the electric f ield. The hole mobility decreases as the doping concentration increase s, indicating that the negatively charged dopants form Coulomb trap s that disturb hole transport in the p-doped organic system. The activa tion energy of the mobility increases as the doping concentration inc reases, consistent with a broadening of the Gaussian density-of-states distribution by the negatively charged dopants. (C) 2013 AIP P ublishing LLC.

We report on the characteristics of enhanced and balanced white-light emission from bi-directional organic light-emitting diodes (BiOLEDs) enabled by the introduction of micro-cavity effects. The insertion o f an additional metal layer between the indium tin oxide anode and the hole transporting layer results in similar light output of our BiOLE Ds in both top and bottom direction and in reduced distortion of the electroluminescence spectrum. Furthermore, we find that by utiliz ing MC effects, the overall current efficiency can be improved by 26.2% compared to that of a conventional device. (C) 2013 Optical Soci ety of America

유기발광다이오드(organic light emitting diodes, OLEDs)는 높은 효율, 안정성, 신물질 개발과 같은 연구들을 바탕으로차세대 디스플 뮌�및 조명으로써의 높은 기술력과 학문적 발전을 달성하였다. 본 논문에서 는 hexaazatrinaphthylene (HAT) 유도체들을 OLEDs 소자의 정공주입층으 로 사용하여 제작된 고효율의 녹색 인광 OLEDs 소자의 특성을 연구하였 다. Indium Tin Oxide (ITO)전극과 정공수송층 사이에 삽입된 박막의 HA T 유도체층은 1,000 cd/m2의 구동 조건에서OLEDs 소자의 외부양자효율 을 기존의 8.8%에서 13.6%로, 전류효율을 30.8 cd/A에서 47.7 cd/A로 각각 향상시켰다. 삽입된 HAT 유도체층은 발광층 내부에서 최적화된 전자-정坪�균형을 이루게 하여 소자의 효율 향상에 기여하였다.