Phenylimidazole-based homoleptic iridium(III) compounds for blue phosphorescent organic light-emitting diodes with high efficiency and long lifetime

초록

In order to obtain triplet emitters with high stability and efficiency, three homoleptic iridium(III) compounds - specifically, Ir(tpim)(3) (1), Ir(mtpim)(3) (2), and Ir(itpim)(3) (3), where tpim = 1-([1,1':3',1 ''-terphenyl]-2'-yl)-2-(4-fluorophenyl)-1H-imidazole, mtpim = 2-(4-fluorophenyl)-1-(5'-methyl-[1,1':3',1 ''-terphenyl]-2'-yl)-1H-imidazole, and itpim = 2-(4-fluorophenyl)-1-(5'-isopropyl-[1,1':3',1 ''-terphenyl]-2'-yl)-1H-imidazole - were prepared by one-pot reaction of the corresponding phenylimidazole ligand with an Ir(I) complex as a starting material. Compounds 1-3 emit bright sky-blue phosphorescence with lambda(max) = 459-463 nm and phosphorescent quantum efficiencies of 0.38-0.50. Multi-layer phosphorescent organic light-emitting diodes using compounds 1-3 as the triplet emitters and mCBP (3,3-di(9H-carbazol-9-yl)biphenyl) as the host have been fabricated. Compound 3 doped in the emissive layer demonstrate external quantum efficiency as high as 20.1% at 1000 cd/m(2). In addition, the device based on compound 1 as an emitter shows a stable lifetime greater than 300 h at 1000 cd/m(2), which is one of the best results concerning the device lifetime. (C) 2016 Elsevier B.V. All rights reserved.

키워드