Ultra high efficiency green organic light-emitting devices

We developed ultra high efficiency green organic light-emitting devices (OLEDs) using a novel electron transport material containing dipyridylphenyl moieties and green phosphorescent emitter, fac tris(2-phenylpyridine)iridium, Ir(ppy)(3). An OLED with a simple structure of glass/indium-tin oxide/polymer buffer layer/arylamine derivative as a hole transport layer/ Ir(ppy)(3)-doped dicarbazolylbiphenyl as an emitter layer/dipyridylphenyl derivative as an electron transport layer/LiF/Al exhibited low drive voltages, which were 2.5 V at 100 cd/m(2) and 2.9 V at 1000 cd/m(2.) High external quantum efficiencies of 29% at 100 cd/m(2) and 26% at 1000 cd/m(2) were also observed, which lead to the ultra high power efficiencies of 133 lm/W at 100 cd/m(2) and 107 lm/W at 1000 cd/m(2).