Improving the performance of blue phosphorescent organic light-emitting devices using a composite emitter

Abstract

A composite emitter is constructed by doping a carrier-transporting material into a conventional emitter composing of only host and dopant. The transport of carriers from either hole- or electron-transporting layer into the emitter can be promoted through the carrier-transporting material, in particular, when a wide-band-gap host material is used. A blue phosphorescent OLED based on iridium(III)bis((4,6-difluorophenyl)-pyridinate-N,C(2)')-pico-linate (FIrpic) as dopant in the composite emitter achieved a power efficiency of 20 lm/W and a low driving voltage of 4.2 V at 1000 cd/m(2), whose current efficiency at 20 mA/cm(2) was 2.5 times better than that of device using the conventional emitter. (C) 2009 Elsevier B.V. All rights reserved.