Host–Guest Cocrystal Enabling Efficient Electrochemiluminescence Based on Thermally Activated Delayed Fluorescence

Thermally activated delayed fluorescence (TADF) materials have garnered significant attention for their capacity to augment electrochemiluminescence (ECL). In this work, three kind of host–guest cocrystals were prepared by incorporating dicyanobenzene (DCB) derivatives as acceptor guests within calix[3]acridan (C[3]A) as donor host. Notably, the ECL signals of C[3]A@o-DCB were significantly stronger than those of C[3]A@p-DCB and C[3]A@m-DCB, attributed to enhanced intermolecular charge transfer (ISCT). Mechanistic investigation, supported by DFT calculations, reveals that the physically separated yet spatially proximate D–A configuration promotes efficient ISCT, leading to enhanced ECL. This study provides insights in designing TADF host–guest cocrystals with favorable properties for ECL.