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-biphe nyl layer were prepared. The device with the 65 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/m(2) driven at the voltage of 4.0 V and current density of 0.215 mA/cm(2). The half decay lifetime und er continuous constant-current driving for the initial luminance of 500 cd/ m(2) was 170 h.