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 similar to 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 CH3NH3PbI3 perovskite solar cells fabricated in air condition with high humidity up to 50%.