We synthesized 3-(3-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-methylphenyl)-9-phenyl-9H-carbazole (TrzmPCz) as a new bipolar host material for blue phosphorescent organic light-emitting devices and investigated the electro-optical properties of the blue devices fabricated using the TrzmPCz host. We managed the triplet energy of the host by inserting a methyl substituent in the phenyl linkage between triazine and carbazole. The methyl substituent distorted the backbone structure of TrzmPCz and lead to high triplet energy of 2.79 eV. After optimization of the device structure, the TrzmPCz based organic light-emitting diodes achieved the maximum quantum efficiency of 16.4%, a current efficiency of 32 cd A⁻¹, and a power efficiency of 21.5 lm W⁻¹.