Solution microcrystal enables a high-quality CsPbIBr2 film to minimize intragranular charge recombination for air-stable, carbon-based photovoltaics

The colloidal nature of perovskite precursor solution highly determines the quality of perovskite film and the photovoltaic performance of a perovskite solar cell (PSC). Herein, we demonstrate a facile method to fabricate a high-quality all-inorganic CsPbIBr 2 film by regulating the temperature of the precursor solution. After characterization, stable microcrystals with a size up to 1 have been formed under high temperatures, more suitable for preferable crystallization by spontaneous nucleation than the precursor solution at room temperature. Consequently, rapid charge transfer across enlarged crystal grain rather than intragranular charge recombination is achieved within the perovskite film because of reduced defects, promoting the efficiency as high as 11.12% for carbon-based PSC, which is higher than that of a control device with 8.51% efficiency. Moreover, the optimal device shows improved stability under air atmosphere and high-temperature conditions.