Carbazole-dibenzothiophene core as a building block of host materials for blue phosphorescent organic light-emitting diodes

A high triplet energy core structure, carbazole-dibenzothiophene, was designed and synthesized as a building block of high triplet energy host materials for blue phosphorescent organic light-emitting diodes. The carbazole and dibenzothiophene were interconnected via 3- position of carbazole and 2- position of dibenzothiophene not to sacrifice the high triplet energy the two units. Three compounds with phenyl, dibenzothiophene and 9-phenylcarbazole functional groups as side groups of the carbazole-dibenzothiophene main structure worked as hosts providing high triplet energy over 2.80 eV and the host with a dibenzothiophene substituent achieved high external quantum efficiency over 20% in blue phosphorescent organic light-emitting diodes.