Controlled Synthesis of Composition Tunable Formamidinium Cesium Double Cation Lead Halide Perovskite Nanowires and Nanosheets with Improved Stability

Lead halide perovskites with well-defined morphology have attracted attention for their unique properties as a promising new class of semiconductor materials in photovoltaics and optoelectronics. However, controlling morphologies and compositions of perovskite nanostructures with improved stability, especially for double cation lead halide perovskite, still remains a challenge. Here, we demonstrate a colloidal synthetic approach for direct synthesis of stable single-crystal formamidinium (FA) cesium double cation lead halide FA0.33Cs0.67PbBr3–xIx (0 ≤ x ≤ 3) perovskite nanostructures with controllable morphology over a wide range of halide compositions, without using a previous anion-exchange process. The presence of FA alloyed in the A site for the pure cesium lead halide perovskite structure can stabilize the nanocrystals while delivering a better balance between structure and composition. On the basis of the FA0.33Cs0.67PbBr3–xIx alloy perovskite system, we achieved nanowires and nanosheets with high yield of various halide compositions by tuning the ligand participating in the reaction. These new perovskite nanostructures with well-defined morphology and compositions demonstrated improved stability and fluorescent and optoelectronic properties, which may allow them to find application as replacements for conventional semiconductor nanostructures in nanoscale devices.