Alkyl-Thiol Ligand-Induced Shape- and Crystalline Phase-Controlled Synthesis of Stable Perovskite-Related CsPb 2 Br 5 Nanocrystals at Room Temperature

Controlled synthesis of colloidal all-inorganic lead halide perovskite semiconductor nanocrystals, such as CsPbBr 3, with tunable size, shape, composition, and crystalline phase have recently attracted wide interest for photonic and optoelectronic applications. Herein, we report a new strategy for using alkyl-thiols to induce the transformation of CsPbBr 3 to perovskite-related cesium lead halide (CsPb 2 Br 5 ) with controlled morphology and a crystalline phase at room temperature. By rational tuning the ratios of the alkyl-thiol ligands to alkyl-amines or to alkyl-acids, the as-synthesized colloidal nanocrystals can be rationally controlled from orthorhombic crystalline-phase CsPbBr 3 to tetragonal-phase CsPb 2 Br 5 nanosheets and nanowires with high yield. Significantly, the tetragonal CsPb 2 Br 5 nanowires and nanosheets have high stability in high-temperature and high-humidity environments. These findings may open new directions for large-scale synthesis of shape- and crystalline phase-controlled perovskite nanocrystals for high-performance, low-cost optical electronic and optoelectronic devices.