Efficient deep-blue luminescence based on dual-channel intra/intermolecular exciplexes
Zhen Zhang, Dehai Dou, Rongrong Xia, Peng Wu, Eduard Spuling, Ke Wang, Jin Cao, Bin Wei, Xifeng Li, Jianhua Zhang, Stefan Bräse, Zixing Wang
Abstract
Highly efficient and stable blue organic light-emitting diodes (OLEDs) cannot be easily obtained simultaneously. In particular, the efficiency roll-off as a reference index to evaluate the lifetime of deep-blue OLED at high luminescence is still severe. A novel molecule ( CzSiTrz ) connected with carbazole and triazine fragments by a nonconjugated silicon atom is designed. An intramolecular charge transfer emission and intermolecular exciplex luminescence in the aggregated state are obtained, resulting in a dual-channel intra/intermolecular exciplex ( DCIE ) emission with fast and efficient reverse intersystem crossing (RISC). Deep-blue OLED with Commission Internationale de l'Eclairage (CIE) coordinates of (0.157, 0.076) and a record-high external quantum efficiency (EQE) of 20.35% at high luminance (5000 cd m −2 ) is accomplished. Simple molecular synthesis and device fabrication of this strategy give a unique approach to realizing high-performance deep-blue electroluminescence.