Investigation of CsPbBr₃ films with controllable morphology and its influence on the photovoltaic properties for carbon-based planar perovskite solar cells

Recently, inorganic CsPbBr₃ perovskites have received much research interest in the photovoltaic field owing to their excellent stability. However, it is still challenging to prepare high-performance CsPbBr₃ films with good crystallinity and superior morphology at moderate temperatures. In this work, we report a novel, to the best of our knowledge, multistep spin-coating deposition method to prepare CsPbBr₃ perovskite film. Through optimizing the number of deposition cycles of a CsBr solution, CsPbBr₃ films containing high phase purity, good crystallinity, and strong absorption are obtained. The inorganic planar perovskite solar cell with optimized CsPbBr₃ film realizes a maximum power conversion efficiency of 4.70% under standard solar illumination conditions. Moreover, our devices with FTO/TiO₂/CsPbBr₃/CuPc/C exhibit fabulous stability when stored in an ambient atmosphere with ∼40% humidity for 60 days. Our work provides new opportunities for facilitating practical application of CsPbBr₃ planar perovskite solar cells.