Ultrasonic Spray-Coated Mixed Cation Perovskite Filmsand Solar Cells

A solar absorber composed of mixed cation perovskite films containing methylammonium (MA) and formamidinium (FA) lead triiodide (MA1–xFAxPbI3) was prepared by continuous ultrasonic spray-coating. This process combined features of substitutional modifications in perovskites and simple yet versatile processing to realize scalable fabrication. Herein, simultaneous growth from a precursor solution with controlled MA/FA stoichiometry in the inverted perovskite solar cells based on MA1–xFAxPbI3 was systematically investigated to link the thin film quality, optical properties, and crystal structures with photovoltaic performance. The result of the inherent advantages of increased photoabsorption, better film quality, and enhanced crystallinity, the perovskite solar cell composed of the MA0.75FA0.25PbI3 (x = 0.25) perovskite achieved an optimum power conversion efficiency (PCE) as high as 15.61% and an average PCE of 15.15 ± 0.45%. In particular, the spray-deposited MA0.75FA0.25PbI3 unencapsulated cells exhibited...