Department of Materials Science and Engineering and §Research Institute of Advanced Materials (RIAM), Seoul National University , Seoul 151-744, South Korea.
ACS Appl Mater Interfaces. 2017 Feb 1;9(4):3277-3281. doi: 10.1021/acsami.6b14438. Epub 2017 Jan 20.
The use of exciplex forming cohosts and phosphors incredibly boosts the efficiency of organic light-emitting diodes (OLEDs) by providing a barrier-free charge injection into an emitting layer and a broad recombination zone. However, most of the efficient OLEDs based on the exciplex forming cohosts has suffered from the short operational lifetime. Here, we demonstrated phosphorescent OLEDs (PhOLEDs) having both high efficiency and long lifetime by using a new exciplex forming cohost composed of N,N'-diphenyl-N,N'-bis(1,1'-biphenyl)-4,4'-diamine (NPB) and (1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl))tris(diphenylphosphine oxide) (PO-T2T). The red-emitting PhOLEDs using the exciplex forming cohost achieved a maximum external quantum efficiency (EQE) of 34.1% and power efficiency of 62.2 lm W with low operating voltages and low efficiency roll-offs. More importantly, the device demonstrated a long lifetime around 2249 h from 1000 cd m to 900 cd m (LT) under a continuous flow of constant current. The efficiencies of the devices are the highest for red OLEDs with an LT > 1000 h.
利用激基复合物形成辅助材料和磷光体可以通过提供无障碍的电荷注入到发射层和广泛的复合区域，极大地提高有机发光二极管（OLED）的效率。然而，大多数基于激基复合物形成辅助材料的高效 OLED 都存在工作寿命短的问题。在这里，我们通过使用由 N,N'-二苯基-N,N'-双（1,1'-联苯）-4,4'-二胺（NPB）和（1,3,5-三嗪-2,4,6-三基）三（苯-3,1-二基）三（二苯基膦氧化物）（PO-T2T）组成的新型激基复合物形成辅助材料，展示了具有高效率和长寿命的磷光 OLED（PhOLED）。使用激基复合物形成辅助材料的红色发射 PhOLED 实现了最大的外量子效率（EQE）为 34.1%，功率效率为 62.2 lm W，工作电压低，效率滚降低。更重要的是，该器件在连续恒流的情况下，在 1000 cd m 至 900 cd m 的亮度下，寿命可达到约 2249 小时（LT）。对于 LT > 1000 h 的红色 OLED，这些器件的效率是最高的。
