Highly efficient orange and white organic light-emitting diodes with low efficiency roll-off based on a novel exciplex host

Realizing highly efficient organic light-emitting diodes (OLEDs) with low efficiency roll-off through exciplex systems remains challenging due to mismatched transport property between donor and acceptor. Herein, a novel exciplex co-host system constructed by 1,1-Bis[(di-4-tolylamino) phenyl] cyclohexane (TAPC) and 2,4-diphenyl-6-(9,9′-spirobi[9H-fluoren]-3-yl)-1,3,5-Triazine (SF3-TRZ) is applied to design simplified orange and white OLEDs with high efficiency and low efficiency roll-offs. The result orange phosphorescent OLED is realized by doping orange dopant into exciplex host, demonstrating outstanding characteristics with a maximum current efficiency of 81.3 cd/A and a maximum power efficiency of 84.7 lm/W. By further inserting a blue emitting layer, the white OLED with stable spectra achieves a current efficiency of 62.1 cd/A with an extremely low roll-off, which represents one of the smallest values reported for exciplex co-host white OLEDs. The superior performance of the device is attributed to the balanced carriers transport and the simplified architecture design. The architecture provides a promising solution for developing high-performance OLEDs toward practical solid-state lighting applications.