High Quantum Efficiency in Organic Light-Emitting Devices with Iridium-Complex as a Triplet Emissive Center

Multilayer organic light-emitting devices with phosphorescent guest emitter, tris(2-phenylpyridine) iridium doped in a host 4,4^‧-N,N^‧-dicarbazol-biphenyl layer were prepared. The device with the 6.5 wt% guest emitter exhibited external quantum efficiency and power luminous efficiency of 13.7% and 38.3 lm/W, respectively at the luminance of 105 cd/m² driven at the voltage of 4.0 V and current density of 0.215 mA/cm². The half decay lifetime under continuous constant-current driving for the initial luminance of 500 cd/m² was 170 h.