High efficiency in two color and three color phosphorescent white organic light-emitting diodes using a 2,7-substituted 9-phenylcarbazole derivative as the host material

High efficiency two color and three color phosphorescent white organic light-emitting diodes (PHWOLEDs) were developed using 2,7-bis(diphenylphosphino)-9-phenyl-9H-carbazole (PPO27) as the host material for blue phosphorescent emitting layer. High external quantum efficiency of 20.1% was achieved in the two color PHWOLEDs with red:blue co-doped single emitting layer and high external quantum efficiency of 20.8% was obtained in the three color PHWOLEDs with stacked structure of red:blue co-doped and green emitting layers. The PPO27 host material was effective as the host material for the red:blue co-doped emitting layer and could give high quantum efficiency in two color and three color PHWOLEDs.

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► External quantum efficiency over 20% in two color white device.
► External quantum efficiency over 20% in three color white device.
► Phenylcarbazole based high triplet energy host material.