Carbazole-modified polyphenylene ether as host materials for high efficiency phosphorescent organic light-emitting diodes

Abstract Two novel polymeric hosts called PPO-Cz and PPO-3Cz for solution-processed green phosphorescent organic light-emitting devices have been designed and synthesized by incorporating electron-donor carbazole units with polyphenylene ether. In order to simplify the synthesis route and save cost, we attached the classic carbazole units directly to the side chain of the polyphenylene ether. This molecular design endows these two polymeric hosts with good thermal stability and high triplet energy levels. PPO-Cz- and PPO-3Cz-based emissive-layer green phosphorescent organic light-emitting diodes were fabricated with simplified device configuration by solution-processed using Ir(mppy)3 as a dopant. These devices exhibited lower turn on voltages. Moreover, the PPO-3Cz-based solution processed device showed maximum current efficiency and external quantum efficiency of 31.8 cd/A and 9.3%, respectively. This result demonstrated that the newly synthesized, polymeric hosts were advantageous for fabrication of highly efficient green phosphorescent organic light-emitting diodes.