Thermally Activated Delayed Fluorescence and Room‐Temperature Phosphorescence in Materials with Imidazo‐pyrazine‐5,6‐dicarbonitrile Acceptors

Abstract Three donor‐acceptor compounds based on the imidazo‐pyrazine‐5,6‐dicarbonitrile (IPDC) acceptor were synthesized. The IPDC emitters exhibit blue to near‐infrared (NIR) emission with up to 54 % photoluminescent quantum yield. 9,9‐Dimethyl‐9,10‐dihydroacridine (ACR), phenoxazine (POX), and phenothiazine (PTZ) served as electron donors. IPDC ‐ POX displayed NIR emission in toluene solution, while showing room‐temperature phosphorescence in the solid state. IPDC ‐ ACR exhibited yellow thermally activated delayed fluorescence. Interestingly, dual‐emissive behavior as well as excitation‐dependent thermally activated delayed fluorescence (TADF) was found for IPDC ‐ PTZ , arising from the two conformers of phenothiazine derivatives. Overall, this work describes a novel strong electron acceptor from the fusion of imidazole, pyrazine, and nitrile functional groups into one conjugated heterocycle for materials exhibiting NIR emission, TADF, and/or room‐temperature phosphorescence (RTP).