A host material containing tetraphenylsilane for phosphorescent OLEDs with high efficiency and operational stability

Abstract

A host material containing tetraphenylsilane moiety, 9-(4-triphenylsilanyl-(1,1′,4,1′′)-terphenyl-4′′-yl)-9H-carbazole (TSTC), was synthesized for green phosphorescent organic light emitting diodes. The tetraphenylsilane moiety was introduced to provide high triplet energy level, thermal and chemical stability, and glassy properties leading to high efficiency and operational stability of the devices. Ir(ppy)3 based OLEDs using the TSTC host and DTBT (2,4-diphenyl-6-(4′-triphenylsilanyl-biphenyl-4-yl)-1,3,5-triazine) hole blocking layer (HBL) resulted in the maximum external quantum efficiency of 19.8% and the power efficiency of 59.4 lm/W. High operational stability with a half lifetime of 160,000 h at an initial luminance of 100 cd/m2 was achieved from an electrophosphorescent device using TSTC host and BAlq HBL.