Multilevel encapsulation-engineered ultra-stable flexible scintillator films for high-resolution X-ray imaging

Lead halide perovskites have emerged as promising scintillators for X-ray imaging owing to their high X-ray absorption efficiency, excellent luminescence properties, and facile synthesis. However, their intrinsic ionic nature poses a fundamental challenge in simultaneously achieving high photoluminescence efficiency and environmental robustness. Here, we introduce a multilevel encapsulation strategy by sequentially coating CsPbBr3 quantum dots (QDs) with Cs4PbBr6, SiO2, and polydimethylsiloxane (PDMS), thereby synergistically enhancing both optical performance and stability. Cs4PbBr6 effectively passivates surface defects of CsPbBr3 QDs, while the SiO2 and PDMS layers serve as protective barriers against moisture, heat, and radiation. The resulting CsPbBr3@Cs4PbBr6/SiO2/PDMS flexible films exhibit a high photoluminescence quantum yield of 85%, outstanding mechanical flexibility, and remarkable durability under stretching, bending, and compressing. Moreover, the films retain excellent emission stability under elevated temperatures, prolonged X-ray irradiation, and extended water immersion. X-ray imaging evaluations further demonstrate a spatial resolution of 12 lp/mm, enabling distortion-free imaging of curved objects, while their superior water resistance allows for long-term underwater X-ray imaging. This work highlights the critical role of hierarchical encapsulation in balancing luminescence efficiency and environmental stability, offering a viable pathway toward practical high-performance flexible perovskite scintillators.