Highly Efficient Bipolar Host Materials with Indenocarbazole and Pyrimidine Moieties for Phosphorescent Green Light-Emitting Diodes

In this paper, we report bipolar host materials, 6-(2,6-diphenyl-pyrimidin-4-yl)-12,12-dimethyl-6,12,12′-trihydroindeno[1,2- b ]carbazole (DPICz1) and 6-(2,6-diphenyl-pyrimidin-4-yl)-12,12-dimethyl-6,12,12′-trihydroindeno[1,2- b ]carbazole (DPICz2), with indenocarbazole moiety as a hole-transporting unit and pyrimidine moiety as an electron-transporting unit for highly efficient green phosphorescent organic light-emitting diodes. The synthesized materials show excellent electro-optical properties. Similarly, it also exhibits outstanding thermal and morphological stability due to high glass transition temperature ( T g ) of 161 °C and decomposition temperature ( T d ) of 327–401 °C. Fabricated green phosphorescent organic light-emitting diode shows excellent current and power efficiency of 77.8 cd/A and 62.8 lm/W as well as almost ideal external quantum efficiency of 22.3% at the brightness of 1000 cd/m 2 .