Dibenzothiophene derivatives as host materials for high efficiency in deep blue phosphorescent organic light emitting diodes

Various dibenzothiophene derivatives were synthesized as high triplet energy host materials for deep blue phosphorescent organic light-emitting diodes (PHOLEDs) and their device performances were investigated. Dibenzothiophene host materials with a hole transport type carbazole and electron transport type phosphine oxide moieties showed high quantum efficiency and low driving voltage due to balanced charge injection and transport. A high quantum efficiency of 20.2% and only 10% reduction of quantum efficiency at 1000 cd m−2 were demonstrated from the deep blue PHOLEDs with the dibenzothiophene based high triplet energy host materials.