Highly efficient nondoped bilayer organic light-emitting diodes based on triphenyl phosphine oxide protected iridium complexes

Nondoped phosphorescent organic light-emitting diodes (OLEDs) with simplified stacks are desired for practical displaying and lighting applications. However, doping emissive layers are commonly adopted due to serious triplet quenching of phosphors. Here, we demonstrate high-efficiency nondoped bilayer OLEDs based on triphenylphosphine oxide protected iridium(III) complexes. The host feature of peripheral phosphine oxide groups effectively suppresses intermolecular interaction induced quenching. As consequence, the maximum external quantum efficiency beyond 20% and near-zero roll-offs at 1000 nits were achieved, comparable to the best nondoped phosphorescence devices.