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.

Stable host materials based on benzocarbazole and quinazoline were synthesized to establish a design strategy of bipolar hosts for elongated lifetime in orange phosphorescent organic light-emitting diodes (PHOLEDs).

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