Multilevel Encapsulation-Engineered Ultra-Stable Flexible Scintillator Films for High-Resolution X-ray Imaging
Lead halide perovskites are promising scintillators for X-ray imaging due to high X-ray absorption efficiency, excellent luminescence, and facile synthesis. However, their ionic nature challenges simultaneous high photoluminescence efficiency and environmental robustness. This work introduces a multilevel encapsulation strategy: CsPbBr3 quantum dots (QDs) are sequentially coated with Cs4PbBr6, SiO2, and polydimethylsiloxane (PDMS). Cs4PbBr6 passivates surface defects, while SiO2 and PDMS provide barriers against moisture, heat, and radiation. The resulting CsPbBr3@Cs4PbBr6/SiO2/PDMS flexible films exhibit a photoluminescence quantum yield (PLQY) of 85%, outstanding mechanical flexibility, and durability under stretching, bending, and compressing. Films retain emission stability under elevated temperatures, prolonged X-ray irradiation, and extended water immersion. X-ray imaging demonstrates spatial resolution of 12 lp/mm, enabling distortion-free imaging of curved objects; superior water resistance allows long-term underwater imaging. This work highlights hierarchical encapsulation in balancing luminescence efficiency and stability, offering a pathway toward practical flexible perovskite scintillators.