Highly Stable CsPbX₃/PbSO₄ Core/Shell Nanocrystals Synthesized by a Simple Post‐Treatment Strategy

Abstract All‐inorganic lead halide perovskite (CsPbX₃, X = Cl, Br, I, or their mixture) nanocrystals (NCs) have recently emerged as a promising photoelectric material; however, developing highly stable CsPbX₃ NCs still remains a challenge due to their intrinsic ionic nature. This work presents a simple and facile post‐treatment strategy to encapsulate CsPbX₃ NC with PbSO₄ nanoshell at single‐particle level. Compared to pristine CsPbX₃ NCs, the as‐prepared CsPbX₃/PbSO₄ NCs exhibit significant enhancement in the optical properties. Benefiting from the efficient protection of inert PbSO₄ nanoshell, the obtained CsPbX₃/PbSO₄ core/shell NCs demonstrate great stability against polar solvents, including ethanol and acetone, and light irradiation. Furthermore, anion‐exchange reaction is strongly restricted upon the encapsulation of PbSO₄ shell. This work provides an alternative approach for the synthesis of highly stable CsPbX₃ NCs, and paves a new way for the preparation of core/shell heterostructures based on lead halide perovskite NCs.