Unusual Stability and Temperature-Dependent Properties of Highly Emissive CsPbBr₃ Perovskite Nanocrystals Obtained from in Situ Crystallization in Poly(vinylidene difluoride)

All-inorganic cesium lead halide perovskite nanocrystals (CsPbX₃, X = Cl, Br, or I) present broad applications in the field of optoelectronics due to their excellent photoluminescence (PL), narrow spectral bandwidth, and wide spectral tunability. However, their poor stability limits their practical application. In this work, we successfully use an in situ crystallization strategy for growing and cladding CsPbBr₃ perovskite nanocrystals in poly(vinylidene difluoride) (PVDF). The CsPbBr₃ nanocrystals in the as-fabricated CsPbBr₃@PVDF composites have an average diameter of 16-18 nm and a strong PL emission (537 nm), with a photoluminescence quantum yield exceeding 30%. In addition, the fabricated CsPbBr₃@PVDF composites present improved resistance to heat and water preserving with remarkable optical performance, owing to the effective protection of PVDF. Moreover, the CsPbBr₃ nanocrystals generated in PVDF can withstand temperatures up to 170 °C and can be completely immersed in water for 60 days while still retaining high PL intensity, which facilitate the practical application of CsPbBr₃ perovskite nanocrystals. These CsPbBr₃@PVDF composite films with remarkable optical performances and superior anti-interference ability have broad application prospects in optoelectronics as well as good potential as temperature sensors in mechanical engineering.