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 y...