Silane coupling di-carbazoles with high triplet energy as host materials for highly efficient blue phosphorescent devices

Abstract

We report the synthesis and characterization of two high triplet energy compounds bis(4-(9-carbazolyl)phenyl)dimethylsilane (DMSiCBP) and bis(4-(9-carbazolyl)phenyl)diphenylsilane (DPSiCBP), which can be used as the host materials for blue phosphorescent devices. Triplet energy of both DMSiCBP and DPSiCBP arrive at a level of 3.0 eV, which is significantly higher than the commonly used host materials for blue phosphorescence, such as CBP(2.6 eV) and mCP(2.9 eV). The DPSiCBP is fully-amorphous with a higher glass transition temperature of 120 °C, and excellent morphologically stability based on DSC analysis and annealing atomic force microscopy (AFM) investigation. The phosphorescent EL devices, employing DPSiCBP doped with blue iridium complex Firpic as the emitting layer, show the maximum brightness of 12130 cd/m² and maximum luminous efficiency of 6.5 cd/A, which is superior to those of CBP-based devices.