Well‐Dispersed CsPbBr₃@TiO₂ Heterostructure Nanocrystals from Asymmetric to Symmetric

Metal halide perovskites (MHPs) have undergone rapid development in the fields of solar cells, light diodes, lasing, photodetectors, etc. However, the MHPs still face significant challenges, such as poor stability and heterocompositing with other functional materials at the single nanoparticle level. Herein, the successful synthesis of well-dispersed CsPbBr₃@TiO₂ heterostructure nanocrystals (NCs) is reported, in which each heterostructure NC has only one CsPbBr₃ with a precise anatase TiO₂ coating ranging from asymmetric to symmetric. Due to the protection of anatase TiO₂, CsPbBr₃ shows dramatically improved chemical stability and photostability. More significantly, the synthesized CsPbBr₃@TiO₂ heterostructure NCs form a type II heterojunction, which strongly promoted efficient photogenerated carrier separation between anatase TiO₂ and CsPbBr₃, hence leading to improved optoelectronic activity. This study provides a robust avenue for synthesizing stable and highly efficient MHPs@metal oxide heterostructure NCs, paving the way for the practical application of all inorganic perovskites.