Fast preparation of uniform large grain size perovskite thin film in air condition via spray deposition method for high efficient planar solar cells

Spray deposition has been demonstrated to be a promising method to prepare perovskite thin film with many advantages, such as easy and processable under fully ambient condition, which is suitable for large-scale production. In this work, we reveal two typical spray deposition process of rapid and slow solvent evaporation . It is emphasized that the rapid solvent evaporation process is essential to avoid dendritic crystal and obtain dense perovskite thin film without pin-holes, which can be realized with a suitable substrate temperature . With optimized spray conditions including flow rate of precursor solution and carrier gas pressure, a dense and uniform perovskite layer with full surface coverage was immediately formed in ~5   s without any post-annealing process. The as-fabricated planar heterojunction solar cell achieved a power conversion efficiency (PCE) of 13.54% with 300±30   nm in thickness of perovskite layer. To the best of our knowledge, this result is the highest value for the CH 3 NH 3 PbI 3 perovskite solar cells fabricated in air condition with high humidity up to 50%.