A novel carbazole moiety with bromine at the 1-position of carbazole was synthesized and four carbazole compounds derived from the 1-position modified carbazole were developed as the host materials for phosphorescent organic light-emitting diodes. The 1-position modified carbazole was coupled with another carbazole to prepare bicarbazole intermediates, which were substituted with 4,6-diphenyltriazine to yield four bicarbazole derivatives modified with the electron deficient diphenyltriazine unit. The triplet host materials showed high quantum efficiency above 20% and low driving voltage below 5.0 V at 1000 cd m⁻² in green phosphorescent organic light-emitting diodes.