Inhomogeneous Pb/Sn elemental distribution and the resulted phase segregation in mixed Pb-Sn halide perovskites would result in energy disorder (band structure and phase distribution disorder),which greatly limits their photovoltaic performance.Here,PbS quantum dot has been synthesized and demon-strated as seeds for modulation crystallization dynamics of the mixed Pb-Sn inorganic perovskites,allow-ing an enhanced film quality and significantly suppressing phase segregation.With this additive power conversion efficiency of 8％ and 6％ is obtained under irradiation of full sunlight in planar and mesoporous structured solar cells in combination with CsPb0.5Sn0.5I2Br inorganic perovskite,respectively.Our finding reveals exploring the actual Pb/Sn atoms location in perovskite structure and its influence on developing efficient and stable low-bandgap perovskite solar cells.