Crystallization kinetic engineering for growth of thin metal halide perovskite platelets

Abstract

Two-dimensional inorganic lead-free metal halide perovskite (MHP) single crystals possess superior photoelectric properties and robust stability and are promising as functional materials with optimized performance. However, controlling the growth habit of MHPs to mass-produce two-dimensional crystals without relying on ligands or spatial constraints has yet to be achieved because of their strong three-dimensional bonding characteristics. Here, we propose a crystallization kinetic regulation strategy for mass production of thin Cs₃Bi₂Br₉ platelet single crystals using an anti-solvent-mediated cooling crystallization (AM-CC) approach. Using Cs₃Bi₂Br₉ as morphology-preserving growth templates, we further synthesized isostructural thin Cs₂AgBiBr₆ platelet single crystals by introducing Ag⁺ during AM-CC. The quantity of Ag⁺ in the system emerged as a critical determinant of Cs₂AgBiBr₆ platelet thickness. The Cs₂AgBiBr₆ platelets exhibited exceptional optical and photo-response properties, surpassing those of polyhedron-shaped Cs₂AgBiBr₆. The versatility of our synthesis approach will enable development of high-quality, low-dimensional MHPs with enhanced properties for a diverse range of future applications.