Deep red/near-infrared electro-fluorescence material with nearly 10% external quantum efficiency based on hybridized local and charge-transfer

Although the hot exciton mechanism with hybridized local and charge -transfer (HLCT) characteristics is a promising molecular design strategy, there are few organic deep red (DR) and near-infrared (NIR) HLCT-type emitters with high external quantum efficiency (EQE). Herein, this work reports three DR/NIR emitters with high EQE, TNZ-3PPOXP, TPANZPOXP, and 2PPOXNZ. These emitters show DR/NIR emission in the neat film, 664 nm for TNZ-3PPOXP, 718 nm for TPANZPOXP, and 724 nm for 2PPOXNZ. Interestingly, the emitters all possess hybridized local and charge -transfer (HLCT) characteristics and potential hot exciton channels. The corresponding non-doped OLED achieve high exciton utilization efficiency (EUE) and NIR emission, 55.6 % @694 nm for TNZ-3PPOXP, 82.8 %@736 nm for TPANZPOXP, and 42.3 %@756 nm for 2PPOXNZ. More importantly, with these emitters as the guest, PO -01 as the phosphorescent sensitizer, and CBP as the host, the sensitization device achieved nearly 10 % EQE, 9.55 %@662 nm for TNZ-3PPOXP, 4.20 %@699 nm for TPANZPOXP, and 4.49 %@702 nm for 2PPOXNZ. To our knowledge, this is one of the highest device efficiencies based on HLCT as the guest.