A bipolar host containing 1,2,3-triazole for realizing highly efficient phosphorescent organic light-emitting diodes

We have developed a novel host material, 9,9'-(2-((4-phenyl-1,2,3-triazol-1-yl)methyl)biphenyl4,4'-diyl)biscarbazole (CBP-TA), for realizing highly efficient blue phosphorescent OLEDs. The maximum external quantum efficiency of the OLED device developed using CBP-TA doped with a blue phosphorescent material was 30% greater than that of a CBP-based device. This enhanced external quantum efficiency resulted from the bipolar properties of the new host, owing to which well-balanced hole and electron transport through the emitting layer was achieved. The excellent bipolar carrier transport properties of the new host were experimentally verified using various OLED device data.