Dual Shielding Balanced Stable Photoluminescence and High Photoresponsivity in MAPbX₃–MAPbBr_<i>n</i>X_3–<i>n</i>@PbBr(OH) Core–Shell Single Crystals

Organic–inorganic lead halide perovskite (MAPbX3, X = Cl, Br, I) single crystals exhibit superior optoelectrical and physical characteristics and have been developed in various optical and electrical applications. However, the poor stability against moisture and light remains the most critical demerit of perovskite materials. In this work, light- and waterproof MAPbBr3-MAPbBr3@PbBr(OH) core–shell single crystals were successfully synthesized by surface engineering-induced transformation from MAPbBr3 to MAPbBr3@PbBr(OH). In addition, an in situ electrode preparation method was developed to construct the Ag/MAPbBr3-MAPbBr3@PbBr(OH)/Ag structure during the crystal growing process. The thickness-adjustable MAPbBr3@PbBr(OH) shell can present dual shielding effects and not only sustains the MAPbBr3 single crystal core with the highest responsivity of 31 mA W1–, response time ∼47 ms, and a detection rate of 4.8 × 1011 Jones but also achieves the embedded MAPbBr3 nanocrystal with bright photoluminescence (quantum yield of 56.1%). Moreover, the similar MAPbCl3-MAPbBrnCl3–n@PbBr(OH) and MAPbI3-MAPbBrnI3–n@PbBr(OH) core–shell single crystals have been prepared, which also exhibit excellent photoresponsivity and high emission. This work provides an effective strategy for the fabrication of high-performance and environmentally stable photodetectors.