| 초록 |
The use of exciplex forming co-hosts 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 have suffered from the short operational lifetime. We demonstrated phosphorescent OLEDs (PhOLEDs) having both high efficiency and long lifetime by using a new exciplex forming co-host 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 PhOLEDs achieved a maximum external quantum efficiency (EQE) of 34.1% and power efficiency of 62.2 lm W-1. The device demonstrated a long lifetime around 2249 hours from 1000 cd m-2 to 900 cd m-2 (LT90) under a continuous flow of constant current. The efficiencies of the devices are the highest for red OLEDs with an LT90＞1000 hours. |
