Triphenylsilyl-Promoted Iridium Complex for High-Performance Green-Yellow Phosphorescent Organic Light-Emitting Diodes

Abstract

In this work, a novel triphenylsilyl-based iridium complex, fac-Ir(tpsp)2(bpp), is developed. Triphenylsilyl groups endow fac-Ir(tpsp)2(bpp) with favorable intermolecular interactions. On the one hand, the steric hindrance of a triphenylsilyl group significantly weakens intermolecular π···π interactions. On the other hand, triphenylsilyl ligands provide several C–H···π interactions for fac-Ir(tpsp)2(bpp). As a result, fac-Ir(tpsp)2(bpp) exhibits a high sublimation yield (78.2%), high photoluminescence quantum yield (97.6%), short lifetime (510.9 ns), low concentration sensitivity (10–6 to 10–4 M), and moderate charge-transporting ability. Phosphorescent devices that utilize fac-Ir(tpsp)2(bpp) as the emitter display high efficiencies (100.9 cd/A, 105.6 lm/W, 27.9%), low roll-off of efficiencies (from 100 to 10,000 cd/m2: 5.3%), relatively low concentration sensitivity (from 5 to 12%), long device lifetime (61,892 h at 100 cd/m2), and very stable electroluminescent spectra (from 1 to 70,000 cd/m2). This performance is comparable to those of previous record green/yellow phosphorescent emitters. More importantly, most of record emitters report limited excellent parameters, and comprehensive emitter-like fac-Ir(tpsp)2(bpp) is rare. These results demonstrate that fac-Ir(tpsp)2(bpp) is a good phosphorescent emitter.