A thermally stable high triplet energy material derived from an indoloacridine core and indole hole transport units, 8,8-bis(4-(1H-indol-1-yl)phenyl)-8H-indolo[3,2,1-de]acridine (BIPIA), was synthesized as the hole transport material for deep blue phosphorescent organic light-emitting diodes. The BIPIA hole transport material showed a high triplet energy of 2.95eV and high glass transition temperature of 142 degrees C. A high quantum efficiency of 19.3% was obtained in the deep blue device using BIPIA as the high triplet energy hole transport material. (C) 2013 Elsevier B. V. All rights reserved.