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 .
An ultra high efficiency blue organic light-emitting device using wide-energy-gap electron-transport material containing 3,5-dipyridylphenyl moieties and blue phosphorescent emitter, FIrpic, was developed. The optimized device showed extremely high power efficiencies of 56 lm/W (53 cd/A) at 100 cd/m2 and 42 lm/W (46 cd/A) at 1000 cd/m2 without light outcoupling enhancement.
We succeeded to fabricate highly efficient blue organic light-emitting devices (OLEDs) by using a phosphorescent emitter, iridium(III) bis[(4,6-di-fluorophenyl)-pyridinate-N,C2']picolinate, and high triplet energy materials as the host and the carrier transport materials. A high power efficiency of 39 lm/W and external quantum efficiency of 21% were obtained at 100 cd/m2.
A series of four-pyridylbenzene-armed biphenyl derivatives were designed and synthesized as an electron-transport and exciton- and hole-block layer for the fac-tris(2-phenylpyridine)iridium (Ir(PPy)3)-based green phosphorescent organic light-emitting devices (OLEDs), giving improved efficiency in comparison to that with both the electron-transport layer of tris(8-hydroxyquinoline)aluminum (Alq3) and the exciton- and hole-block layer of 2,9-dimethyl-4,7-diphenylphenathroline (BCP).
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