Liu, Guan‐ChengGuan‐ChengLiuHuang, Tzu‐HaoTzu‐HaoHuangChen, Yi‐YunYi‐YunChenKung, Yu‐ChengYu‐ChengKungLo, Yuan‐ChihYuan‐ChihLoHung, Wen‐YiWen‐YiHungWong, Ken‐TsungKen‐TsungWong2025-07-182025-07-182025-06-05https://scholars.lib.ntu.edu.tw/handle/123456789/730741Two new acceptors, C-BPhCN and N-BPhCN, with 2,3-dicyanopyrazinophenanthrene and pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile core and ortho-linked biphenyl peripherals were synthesized and characterized. The exciplex formation of C-BPhCN and N-BPhCN as acceptor (A) and SBFC-G1 as donor (D) was examined. Through optimization, the device using a D:A (2:1) blend in emitting layer (EML) exhibited maximum external quantum efficiency (EQEmax) of 8.26% and 5.25% with electroluminescence peak (EL λmax) centered at 581 and 595 nm, respectively. A new D–A–D configured near-infrared (NIR) fluorescent emitter DMACBBT was introduced as a dopant in the exciplex-forming cohost system. By tuning the thickness of the electron transporting layer (ETL), the EQEmax of the device employing SBFC-G1:C-BPhCN (2:1): 9 wt % DMACBBT as the EML reached 1.03% with EL λmax at 808 nm. The counterpart device utilizing SBFC-G1:N-BPhCN (2:1): 9 wt % DMACBBT as the EML exhibited an EQEmax of 1.01% and EL λmax at 817 nm. The stability of the NIR OLED device was measured, yielding lifetimes (T60) of 182 and 126 h for SBFC-G1:C-BPhCN and SBFC-G1:N-BPhCN cohost-based devices, respectively. This work highlights the high efficiency of NIR OLEDs that can be practically realized by using the exciplex cohost systems with a tailor-made NIR fluorescent emitter.enEnergy transferExciplexIntermolecular charge transferNear infrared emissionThermally activated delayed fluorescence[SDGs]SDG7journal article10.1002/asia.202500357