Highly efficient, little efficiency roll-off orange-red electrophosphorescent devices based on a bipolar iridium complex

Abstract

A novel phosphorescent emitter BZQPG possessing bipolar charge transporting ability realizes the most efficient orange-red electroluminescence reported to date with the power efficiency of 77.1 lm W⁻¹ and external quantum efficiency of 27.3% together with low efficiency roll-off (>50 lm W⁻¹ and 26% at 5000 cd m⁻²).