Efficient Organic D‐π‐A Scintillators for Temperature‐Adaptive X‐Ray Imaging

Abstract Achieving highly efficient organic scintillators for X‐ray imaging remains a significant challenge, primarily owing to the inherent difficulty in facilitating rapid radiative decays of both singlet and triplet excitons. To address this limitation, a novel design strategy is introduced that incorporated fluorine atoms to modify the π‐bridge of D‐π‐A molecules, thereby fine‐tuning their electronic structures and photophysical properties. The emitters, namely 1FAT and 2FAT, show excellent thermally activated delayed fluorescence (TADF), aggregation‐induced delayed fluorescence (AIDF), and room temperature phosphorescence (RTP) excited by ultraviolet light varying with surrounding environments. Notably, the doped PMMA film of 1FAT exhibites intense emission across a broad temperature range from 77 to 363 K, showcasing its adaptability to diverse thermal conditions. More importantly, 1FAT@PMMA film exhibits excellent radioluminescence performance under X‐ray excitation with a low detection limit of 62.27 nGy s −1 and a high spatial resolution of over 20 lp mm −1 . This study introduces a novel and fundamental design strategy for developing efficient, temperature‐adaptive D‐π‐A organic scintillators, significantly expanding their potential applications in flexible, stretchable X‐ray detectors and advanced imaging technologies.