Efficiency enhancement and voltage reduction in white organic light-emitting devices

Abstract

High-efficiency and low operating voltage fluorescent white organic light-emitting devices (WOLEDs) have been realized by doping either 4,7-diphenyl-1,10-phenanthroline (BPhen) or N, N′ -bis(1-naphthyl)- N, N′ -diphenyl- 1, 1′ -biphenyl- 4, 4′ -diamine (NPB) into the blue light-emissive layer. Devices doped with BPhen (or NPB) exhibited a maximum power efficiency of 8.7 lmW (7.6 lmW), about 74% higher than that of the reference device (5.0 lmW). Such performance improvement is ascribed to the incorporation of a better electron-transporting layer and an improved carrier transport through the emissive layer by mixing with the higher drift mobility materials. It provides a simple and general means to improve the power efficiency of WOLED. © 2007 American Institute of Physics.