Cost-effective synthesis of carbazole/triphenylsilyl host materials with multiple σ-π conjugation for blue phosphorescent organic light-emitting diodes

Two novel multiple sigma-pi conjugated host materials based on both C-Si and N-Si bonding in donor-acceptor molecular architecture were designed and prepared in a highly efficient synthetic method to simultaneously introduce multiple arysilanes to carbazole in one-step and one-pot. These silicon-containing arysilanes/carbazole hybrid hosts show high thermal stability, good film-forming property, high triplet energy, suitable frontier orbital energy level, and acceptable carrier mobility due to enhanced d-orbital participation in the multiple sigma-pi conjugation through direct N-Si and C-Si coupling. Impressively, the multiple sigma-pi conjugated host materials also exhibit independently modified the electrical properties without influence the photophysical properties, rendering much improved device performance with maximum external quantum efficiency of 15.8% in blue phosphorescent organic light-emitting diodes (PhOLEDs). These findings highlight the significant importance of the multiple sigma-pi conjugation strategy in designing cost-effective and high-performance sigma-pi conjugated semiconductors for advanced optoelectronic applications.