Facile Fabrication of Highly Stable and Wavelength-Tunable Tin Based Perovskite Materials with Enhanced Quantum Yield via the Cation Transformation Reaction

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Metal halide perovskites have attracted great attention for their superior light energy conversion applications. Herein, we demonstrated a facile synthesis of zero-dimensional Sn 2+ perovskite Cs 4– x M x SnBr 6 (M = K + and Rb + ) material through the cation transformation reaction at room temperature. Cs 4 SnBr 6 NCs was mixed with pure metal bromide salts (KBr and RbBr) via the mechanochemical process to successfully synthesize Cs 4– x M x SnBr 6 perovskite where transformation of Cs to mixed Cs/Rb and mixed Cs/K was achieved. By substituting different cations, the bright fluorescence of the Cs 4– x M x SnBr 6 was tuned from dim green to greenish-cyan while achieving the photoluminescence (PL) quantum yield of ∼39%. The crystal structure of Sn based perovskite with the substitution of K + or Rb + cations was determined by X-ray diffraction (XRD). Moreover, the Cs 4– x M x SnBr 6 demonstrated superior air stability and exhibited a better photocatalytic activity for CO 2 reduction reaction (CO 2 RR) with high selectivity of CH 4 gas with a higher yield rate compared to the pristine Cs 4 SnBr 6 NCs.