Simultaneous Achievement of High Efficiency and Long Lifetime in Deep Blue Phosphorescent Organic Light-Emitting Diodes

High triplet energy exciplex hosts are developed using new electron transport type hosts with triphenylsilyl blocking groups to obtain high solid state triplet energy and exciplex triplet energy. Two triphenyltriazine derived hosts, 2-phenyl-4,6-bis(4-(triphenylsilyl)phenyl)-1,3,5-triazine (pSiTrz) and 2-phenyl-4,6-bis(3-(triphenylsilyl)phenyl)-1,3,5-triazine (mSiTrz), are synthesized as the high triplet energy hosts with electron transport properties. The two hosts show high triplet energy over 2.90 eV both in solution and solid film, and afford high triplet energy over 2.90 eV in the mixed hosts with a hole transport type 2,2′-di(9H-carbazol-9-yl)-1,1′-biphenyl (oCBP) host. The doping of a deep blue phosphorescent emitter in the mixed host oCBP:mSiTrz achieves high external quantum efficiency over 20% with a color coordinate of (0.14, 0.16) and device lifetime of longer than 1000 h at 100 cd m^-2. This is the first demonstration of simultaneous achievement over 20% external quantum efficiency (EQE) and 1000 h lifetime in the deep blue organic light-emitting diodes with a x+y color coordinate value below 0.30.