Aged\nPrecursor Solution toward Low-Temperature Fabrication\nof Efficient Carbon-Based All-Inorganic Planar CsPbIBr<sub>2</sub> Perovskite Solar Cells

Inorganic\nhalide perovskite CsPbIBr₂ with superior stability\nis regarded as a promising candidate for photovoltaic cells. However,\na high-temperature annealing recipe (∼300 °C) is generally\nrequired to fulfill the crystallization of pure-phase CsPbIBr₂ films. Herein, we report that precursor solution aging time\nstrikingly affects the crystallization kinetics of CsPbIBr₂ film in a one-step spin-coating method. Upon control of this subtle\nfactor, crystallization temperature of pure-phase and full-coverage\nCsPbIBr₂ films can be greatly lowered to 100 °C. Carbon-based\nall-inorganic planar cells with these CsPbIBr₂ films yield\na record efficiency of 6.55%, coupled with excellent long-term operational\nstability against moisture and heat. Our work for the first time suggests\nthat CsPbIBr₂ precursor aging time should be carefully\nconcerned in a one-step solution method, and suggests a facile strategy\nto realize efficient and stable all-inorganic perovskite solar cells.