A high Tg carbazole-based hole-transporting material for organic light-emitting devices

A new branched carbazole derivative, 1,3,5-tris(2-(9-ethylcarbazyl-3) ethylene)benzene (TECEB), was prepared as a hole-transporting material for organic light-emitting devices (OLEDs). TECEB is comparable to 1,4-bis(1-naphthylphenylamino)biphenyl (NPB) in terms of highest-occupied molecular orbital/lowest-unoccupied molecular orbial energy levels, hole-drift mobility, as well as device performance (maximum luminence of about 10 000 cd m^-2 and current efficiency of 3.27 cd A^-1) in a standard hole-transporting layer/tris-(8-hydroxyquinoline)aluminum double-layer device, but is superior to NPB in terms of its higher glass-transition temperature (T_g, 130°C) and ease of synthesis. The latter features suggest that TECEB can be a potential alternative material to NPB especially for high-temperature applications in OLEDs and other organic electronic devices.