Molecular evolution of host materials by regular tuning of n/p ratio for high-performance phosphorescent organic light-emitting diodes

Abstract

By gradually increasing the n/p molar ratio to 2 : 1, the obtained bipolar host material exhibits a turn-on voltage of 2.6 V and an efficiency of 48.1 lm W−1, which is the lowest turn-on voltage and one of the highest power efficiencies ever reported for FIrpic devices containing a single host.