Emerging organic X‐ray scintillators enabled by thermally activated delayed fluorescence

Abstract Organic X‐ray scintillators offer molecular tunability and solution‐processable screen fabrication, yet their performance is constrained by weak energy deposition, incomplete harvesting of radiation‐generated triplet states, condensed‐phase emission losses, and lateral photon transport. Thermally activated delayed fluorescence (TADF) can recycle triplet excitations through reverse intersystem crossing, but efficient molecular TADF does not by itself guarantee strong radioluminescence or high‐resolution imaging. This review therefore organizes TADF‐centered organic scintillation along the full radiation‐to‐readout pathway. Charge‐transfer/locally excited‐state mixing and through‐space coupling are discussed as regulators of triplet‐to‐singlet conversion, while hot‐exciton conversion through upper excited states is treated as a related but mechanistically distinct route. Covalent, ionic, coordination‐based, and functionally separated high‐atomic‐number (high‐Z) designs are then examined in terms of the balance between X‐ray energy deposition and emissive‐state retention. Finally, molecular packing, host and glass environments, polymer immobilization, excitation migration, photon transport, and screen architecture are connected to detector‐collected output. Standardized light‐yield calibration, time‐resolved radioluminescence, thickness‐dependent modulation transfer function analysis, and multiscale modeling are identified as priorities for reproducible, application‐matched scintillation screens.