The organic-inorganic halide hybrid perovskite solar cells (PSCs) constitute the most promising next-generation photovoltaics since, over the period of a decade, the power conversion efficiency (PCE) record increased from 9.7% to 25.7%. [1] The outstanding optoelectronics property of perovskite material benefits from its tunable bandgap energy, [2] high-light-absorption coefficient, [3] longcarrier-diffusion length, and high carrier mobility, [4] etc. Although perovskite materials possess an advantage in defect tolerance, the potential remains for development between practical efficiency values and theoretical PCE exceeding 30%. [5] In general terms, high-quality perovskite films are sensitive to moisture and require fabrication under an inert gas environment or at ambient featuring low humidity. Additionally, water erosion results in the degradation of perovskite and the formation of defects induced by ionic vacancy, especially at the grain boundaries and interfaces of the perovskite. [6] During the nucleation and growth of perovskite grains, defect-induced non-radiative recombination is inevitable. It has been reported that the trap density in polycrystalline perovskite films is about 10 15 % 10 17 cm À3 , while that is 10 11 %10 14 cm À3 in single-crystal perovskites. [7] This indicates that the defects are predominantly concentrated at grain boundaries and surfaces of perovskite films. Therefore, enhancing crystallization, enlarging crystal