Efficient single layer solution-processed blue-emitting electrophosphorescent devices based on a small-molecule host

Abstract

We report highly efficient single layer solution-processed blue small-molecule electrophosphorescent organic light-emitting diodes with iridium (III) bis[2-(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) doped into a wide-gap 9,9-bis[4-(3 c6-di-tert-butylcarbazol-9-yl)phenyl]fluorene (TBCPF) as the emission layer. An optimized device with 1,3-bis[(4-tert-butylphenyl)-1,3,4-oxidiazolyl]phenylene as the electron-transporting component doped into the emission layer, with a blue electrophosphorescence peaked at 474nm from FIrpic, shows a maximum luminance efficiency of 12.7cd∕A at 190A∕m2 and brightness of 19900cd∕m2 at 20V. We attribute the high performance to the excellent film forming ability and high triplet energy of TBCPF.