Highly efficient green phosphorescent organic light-emitting diodes based on tetraphenyl silicon derivative host materials

We report herein two novel tetraphenyl silicon derivatives, bis(4-(dibenzo[b,d]thiophen-4-yl)phenyl)diphenylsilane (DBTSiDBT) and bis(4- (dibenzo[b,d]furan-4-yl)phenyl)diphenylsilane (DBFSiDBF) achieved by coupling dibenzothiophene (DBT) and dibenzofuran (DBF) moieties with bis(4-bromophenyl)diphenylsilane. These two compounds show high triplet energy states, high glass transition temperature (Tg) and high decomposition temperature (Td). Therefore, they can serve as hosts in organic light-emitting diodes. Consequently, (2-phenylpyridine) iridium(III) (Ir(ppy)3) based phosphorescence organic light-emitting diodes (PHOLEDs) with green emission were studied with DBTSiDBT and DBFSiDBF as host materials. The champion external quantum efficiency (EQE) and maximum luminance of the devices were 24.5% and over 27000 cd/m2 respectively.