Chen, Yi YunYi YunChenKung, Yu ChengYu ChengKungWang, MiaoshengMiaoshengWangLo, Yuan ChihYuan ChihLoChia, Yao TeYao TeChiaWang, Chun KaiChun KaiWangChen, Deng GaoDeng GaoChenCheng, Ju TingJu TingChengPI-TAI CHOUWu, ChichiChichiWuLi, Elise Y.Elise Y.LiHu, BinBinHuHung, Wen YiWen YiHungKEN-TSUNG WONG2024-02-272024-02-272024-01-012195-1071https://scholars.lib.ntu.edu.tw/handle/123456789/639990Two blends comprising new dicyanopyrazine-based acceptors (m-CN and p-CN) and a carbazole-based donor CPTBF are explored for exciplex formation. The CPTBF:m-CN and CPTBF:p-CN blends show the signature red-shifted emission together with the delayed fluorescence observed in time-resolved measurement, manifesting the characteristics of thermally activated delayed fluorescence (TADF). The electroluminescence (EL) device employing CPTBF:m-CN (CPTBF:p-CN) blend as the emitting layer (EML) achieved an EQE of 5.22% (2.05%) with the EL λmax centered at 607 nm (625 nm). The exciplex excitons can be efficiently extracted by a new benzobisthiadiazole-based near-infrared (NIR) emitter DCzPBBT, where a device is configured with CPTBF:m-CN: (5 wt.%) DCzPBBT as the EML to achieve a high EQE of 5.32% and an EL λmax 758 nm. Further increase of the doping concentration to 10 wt.% of DCzPBBT exhibits a bathochromic shifted EL λmax to 772 nm with 94% spectral coverage in the NIR (>700 nm) region, while the device EQE retains at 4.06%. The superior device performance stems from the highly efficient energy transfer between the exciplex-forming host and NIR dopant together.enexciplex | intermolecular charge transfer | near-infrared | thermally activated delayed fluorescence[SDGs]SDG7journal article10.1002/adom.2023031312-s2.0-85184725980https://api.elsevier.com/content/abstract/scopus_id/85184725980