High thermal-stability benzocarbazole derivatives as bipolar host materials for phosphorescent organic light-emitting diodes

Two novel host materials based on 5- and 9-substituted benzocarbazole have been developed for application in phosphorescent organic light-emitting diodes. Both host materials exhibit excellent thermal stability with high decomposition temperatures of ca.515 °C, while the 9-substituted benzocarbazole derivative exhibits a high glass transition temperature of 181 °C. Additionally, the electroluminescence characteristics of green phosphorescent organic light-emitting diodes made with two new host materials were also evaluated. The devices exhibited an electroluminescent emission peak at 528 nm with CIE coordinates of (0.31, 0.64) and possessed low turn-on voltages of <2.84 V.