Efficient Blue Phosphorescent Organic Light-Emitting Diodes by Tuning Iridium(III) Phenylpyridine Complexes

Abstract

We demonstrated efficient blue electrophosphorescence using the Ir(OMeppy)(2)(acac) [OMeppy = 2-(phenyl)-4-methoxypyridine, acac = acetylacetonate], Ir[(CF3)(2)ppy](2)(acac) [(CF3)(2)ppy = 2-(3', 5'-bistrifluoromethyl phenyl)-pyridine], Ir[(CF3)(2)OMeppy](2)(acac) [(CF3)(2)OMeppy = 2-(3',5-bistrifluoromethyl phenyl)-4-methoxypyridine] based on Ir(ppy)(2)(acac) (ppy=phenylpyridine). The methoxy group was substituted on the 4-position of pyridyl ring as electron donating group (EDG) and the trifluoromethyl group was substituted on the 3'5'-position of phenyl ring as electron withdrawing group (EWG). The organic light-emitting diodes (OLEDs) with Ir(OMeppy)(2)(acac), Ir[(CF3)(2)ppy](2)(acac), Ir[(CF3)(2)OMeppy](2)(acac) and Ir(ppy)(2)(acac) have maximum luminous efficiency of 42.54 cd/A, 13.67 cd/A, 7.06 cd/A and 40.70 cd/A, respectively. Also, their electroluminescent (EL) emission appeared at 533 nm, 475 nm, 471 nm and 522 nm, respectively.