Liquid-solid-Interpenetration Surface Reconstruction of Monodisperse Water Stabilized CsPbBr3/CsPb2Br5 Core/Shell Perovskite Nanocrystals

All-inorganic lead halide perovskite nanocrystals (NCs) have shown great potential in various optoelectronic device applications due to their excellent optoelectronic properties, but their poor stability remains a key obstacle to widespread application. The preparation of core/shell NCs is developed to improve their stability, but most of the coating for single NCs is incomplete, and the crystal orientation and interface binding of core/shell structures are still unclear. Here, a surface reconstruction strategy to synthesize CsPbBr 3 /CsPb 2 Br 5 core/shell NCs with uniform coating structure is reported. The concentration of [PbBr 8 ] 6− monomer in the system is regulated by creating local low H 2 O concentration conditions to balance the erosion of perovskite by water and the overall heterogeneous nucleation reaction system, resulting in single encapsulated and well-edged perovskite core/shell NCs. More importantly, advanced characterization tools are used to reveal the core/shell structural features of CsPbBr 3 /CsPb 2 Br 5 core/shell NCs at the atomic scale, which has not been reported before, and the interface matching of the two-phase binding is simulated by density functional theory calculations, which confirm that the CsPb 2 Br 5 (116) facet can bind to the CsPbBr 3 (100) facet with the lowest binding energy. The prepared core/shell perovskite NCs can still retain photoluminescence emission after >30 days in water.