Fluorene-triphenylamine-based bipolar materials: Fluorescent emitter and host for yellow phosphorescent OLEDs

Abstract

In this study, two new bipolar materials were designed and synthesized: N1-(9,9-diphenyl-9H-fluoren-2-yl)-N1-(4,6-diphenylpyrimidin-2-yl)-N4,N4-diphenylbenzene-1,4-diam ine (FLU-TPA/PYR) and N1-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-N1-(9,9-diphenyl-9H-fluoren-2- yl)-N4,N4 diphenylbenzene-1,4-diamine (FLU-TPA/TRZ). We fabricated two different devices, namely a yellow phosphorescent organic light-emitting diode (PhOLED) and a non-doped fluorescent OLED emitter with both FLU-TPA/PYR and FLU-TPA/TRZ. The FLU-TPA/PYR host-based yellow PhOLED device showed better maximum current, power and external quantum efficiencies at 21.70 cd/A, 13.64 lm/W and 7.75%, respectively. The observed efficiencies were better than those of the triazine-based FLU-TPA/TRZ. The non-doped fluorescent device with the triazine-based FLU-TPA/TRZ material demonstrated current, power and external quantum efficiencies of 10.30 cd/A, 6.47 lm/W and 3.57%, respectively.