LAUSR

Efficient white lighting sources based on phosphorescent organic light emitting diodes (PhOLEDs) have been predicted as the next generation of highly efficient general illumination systems. This study proposed a novel host material, CzppT, featuring the characteristics of bipolarity while possessing electron-withdrawing pyridine and electron-donating carbazole groups in the hexaphenylbenzene core, suitable for use in both blue and white PhOLEDs. The CzppT possesses a high triplet energy level and thermally activated delayed fluorescence stable which is confirmed by the high value of Td (480 °C). The effect of the emission layer deposition method on the characteristics of the device was studied in the dicarbazole derivative fabricated in a hole and electron-only device to ensure the bipolarity of CzppT. A blue PhOLED device exhibited a maximum external quantum efficiency of 11.0% with CIE coordinates (x, y) of (0.18, 0.41). Moreover, a white PhOLED device doped with a dye has a maximum external quantum efficiency of 11.3%, and CIE coordinates (x, y) of (0.32, 0.36). These results demonstrate that the hexaphenylbenzene derivative was conveniently synthesized with bipolarity and hole- and electron-transporting ability and high triplet energy level. Moreover, as a host material, it is expected to be applied to bipolar, high EL efficiency OLEDs in the future.