Efficient hole-transporter for phosphorescent organic light emitting diodes with a simple molecular structure

Abstract N,N-diphenyl-4-(quinolin-8-yl)aniline (SQTPA), which composes a triphenylamine group and a quinoline group, has been synthesized and employed as a hole-transporter in phosphorescent OLEDs. It has been proved that SQTPA has efficient hole-transport property with a hole-mobility of 3.60 × 10 −5 cm 2 /V s at the electric field of 800 (V/cm) 1/2 , which is higher than that of NPB (1.93 × 10 −5 cm 2 /V s). Blue, orange and green phosphorescent OLEDs have been fabricated based on FIrpic, Ir(2-phq) 3 , Ir(ppy) 3 with typical structures by using SQTPA as the hole-transporter. The SQTPA-based devices show maximum external quantum efficiencies and power efficiencies of 17.5%, 32.5 lm/W for blue, 12.3%, 20.5 lm/W for orange and 20.3%, 64.5 lm/W for green. The performances of SQTPA-based devices are much better than that of NPB-based phosphorescent OLEDs with similar structures. Thought of its very simple molecular structure and easy synthetic route, SQTPA should be an efficient hole-transporter for phosphorescent OLEDs.