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

All-inorganic cesium lead halide perovskite nanocrystals (CsPbX, 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 CsPbBr perovskite nanocrystals in poly(vinylidene difluoride) (PVDF). The CsPbBr nanocrystals in the as-fabricated CsPbBr@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 CsPbBr@PVDF composites present improved resistance to heat and water preserving with remarkable optical performance, owing to the effective protection of PVDF. Moreover, the CsPbBr 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 CsPbBr perovskite nanocrystals. These CsPbBr@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.