Efficient deep-blue phosphorescent organic light-emitting device with improved electron and exciton confinement

We report a significant improvement in the efficiency of deep-blue phosphorescent organic light-emitting devices based on the electrophosphorescent dye bis(4',6'-difluorophenylpyridinato)tetrakis (1-pyrazolyl) borate (FIr6). Using 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) as the hole transport layer (HTL), we achieved a maximum external quantum efficiency of eta(EQE)=(18 +/- 1)%, which is approximately 50% higher than eta(EQE)=12% in a previously reported device with bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl as the HTL. The maximum luminous power efficiency was also improved from (14 +/- 1) lm/W to (18 +/- 1) lm/W. We attribute this efficiency improvement to the enhanced electron and exciton confinement provided by TAPC. (C) 2008 American Institute of Physics.