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

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.