LAUSR

Abstract Four bipolar materials including of CN-TAZ-1Cz, CN-TAZ-2Cz, CN-TAZ-3Cz and CN-TAZ-4Cz were successfully designed and synthesized by incorporating electron-accepting cyano, 1, 2, 4-triazole and pyridine and electron-donating carbazole. The synthesized materials displayed deep-blue and blue emissions in the range of 404–475 nm in CH2Cl2 solution and thin film. The charge-transfer (CT) excited state in CN-TAZ-1Cz and CN-TAZ-3Cz resulted in a large redshift of 163 and 144 nm with the increasing polarities of solvents. The dominated local-electron (LE) and weak CT excited state were observed in emission of CN-TAZ-2Cz, while CN-TAZ-4Cz exhibited mainly CT excited state with redshift of 23 nm. Their performances in organic light-emitting devices (OLEDs) were characterized by using titled bipolar materials as emitting materials and hosts. The non-doped blue device based CN-TAZ-3Cz exhibits the maximum EQE of 3.9% and the. The device hosted CN-TAZ-3Cz and doped Ir(ppy)3 achieved the maximum current efficiency of 64.5 l m/W, external quantum efficiency (EQE) of 18.4% and radiative exciton yield of 66%.