Alkyl-Thiol Ligand-Induced Shape- and Crystalline Phase-Controlled Synthesis of Stable Perovskite-Related CsPb2Br5 Nanocrystals at Room Temperature

Controlled synthesis of colloidal all-inorganic lead halide perovskite semiconductor nanocrystals, such as CsPbBr3, 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 CsPbBr3 to perovskite-related cesium lead halide (CsPb2Br5) 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 CsPbBr3 to tetragonal phase CsPb2Br5 nanosheets and nanowires with high yield. Significantly, the tetragonal CsPb2Br5 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.