Highly efficient green phosphorescent single-layered organic light-emitting devices

The authors studied the highly efficient green electrophosphorescent light-emission from single-layered organic light-emitting devices made by a simple wet process with a composite solution. The solution was prepared by predissolving organic charge transport, host compounds with green phosphorescent guest iridium complex, and a copolymer of oxadiazole units. The fabricated devices show excellent performances, i.e., operation at relatively low voltages, resulting in a high peak current efficiency (ηc) of 48cd∕A and power efficiency (ηp) of 45lm∕W at a current density of 0.02mA∕cm2. Even at 1000cd∕m2 (2mA∕cm2), high ηc of 50cd∕A and ηp of 22lm∕W were obtained.