Multiresonance Thermally Activated Delayed Fluorescence Copolymer Scintillators for Efficient X-ray Imaging

Efficient, flexible, and solution-processable organic polymeric scintillators are urgently needed for diverse applications. However, conventional organic scintillators face intrinsic limitations in their exciton utilization efficiency and X-ray absorption capability. Herein, we introduce a design strategy for high-performance polymer scintillators by covalently integrating multiresonance thermally activated delayed fluorescence emitters into a bromine-functionalized copolymer matrix through facile free-radical copolymerization. The resulting copolymer scintillators exhibit enhanced exciton utilization through efficient reverse intersystem crossing and markedly improved X-ray absorption, owing to bromine incorporation. The optimized material achieves bright radioluminescence peaked at 500 nm, with a narrow full width at half-maximum of 46 nm. This scintillator achieves a high spatial resolution of 10 lp/mm, as determined by a standard line-pair test pattern, along with an exceptionally low detection limit of 301 nGy/s. Practical X-ray imaging applications confirm its capability to distinctly visualize intricate internal structures, validating its potential for clinical and industrial applications. This work establishes a versatile molecular design strategy for the development of advanced organic scintillators.