<i>In Situ</i> Phase-Transition Crystallization of All-Inorganic Water-Resistant Exciton-Radiative Heteroepitaxial CsPbBr₃–CsPb₂Br₅ Core–Shell Perovskite Nanocrystals

The instability of the metal halide perovskites upon exposure to moisture or heat strongly hampers their applications in optoelectronic devices. Here, we report large-yield synthesis highly water-resistant total-inorganic green luminescent CsPbBr3/CsPb2Br5 core/shell heteronanocrystals (HNCs) by developing an situ phase-transition approach. It is implemented via water-driven phase transition original monoclinic CsPbBr3 nanocrystal and resultant tetragonal CsPb2Br5 nanoshell has a small lattice mismatch with core, which ensures formation epitaxial interface for synthesised HNCs. These HNCs maintain nearly 100% luminescence intensity after immersion water 11 months drops only 81.3% at 100 °C. Transient spectroscopy density functional theory calculation reveal that there are double radiative recombination channels core nanocrystal, electron potential barrier provided significantly improves exciton rate. A prototype quasi-white light-emitting device based on these robust realized, showing strong competence solid-state lighting wide color-gamut displays.