Red Host Materials Based on Carbazole/Triphenylsilane Unit for Phosphorescent Organic Light-Emitting Diodes

Abstract

In this study, we designed and synthesized two host materials for phosphorescent organic light-emitting diodes (PhOLEDs) based on carbazole with good hole-transporting ability and a triphenylsilane group with the bulky structural features required to prevent self-aggregations. A device using 9-(4-(triphenylsilyl)phenyl)-9H-carbazole (1) as the host material with the red phosphorescent dopant, bis(2-phenylquinolyl-N,C(2'))iridium(acetylacetonate), displayed enhanced properties compared to 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) as host material with an external quantum efficiency (EQE) of 12.38%, a luminous efficiency of 24.24 cd/A, and a power efficiency of 7.52 Im/W at 20 mA/cm(2), with CIE chromaticity coordinates of (0.60, 0.39) at 8.0 V. This study suggests that the high triplet energy level and effective energy transfer from host to dopant would be important roles in electroluminescent properties of devices.