Aged Precursor Solution toward Low-Temperature Fabrication of Efficient Carbon-Based All-Inorganic Planar CsPbIBr2 Perovskite Solar Cells

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