Vapor-assisted crystallization control toward high performance perovskite photovoltaics with over 18% efficiency in the ambient atmosphere

Vapor-assisted deposition of organometal trihalide perovskite films shows particular advantages in high-quality film preparation and mass-production because of the precisely controlled vapor-solid reaction. However, a high-vacuum environment is required for the deposition process, which is not suitable for the production of low-cost next-generation solar cells. Here, a modified vapor-assisted deposition method for high-quality perovskite films fully under the ambient atmosphere has been developed that exhibits superior ambient tolerance, even at high relative humidity of over 60%. The crystallization behaviors of the perovskite films were investigated in detail, and were highly dependent on the vapor diffusion and reaction at the interface and film recrystallization induced by the proposed in situ annealing process. The uniform, high-quality perovskite films produced efficient perovskite photovoltaics with power conversion efficiency of over 18% (highest value of 18.90%).