Hot Gas-Blowing Assisted Crystallinity Management of Bar-Coated Perovskite Solar Cells and Modules

The bar-coating technique for perovskite solar cells has been studied as a scalable process in relation to solar cell commercialization. In large-area bar coating, solvents with the high boiling points like dimethylformamide or γ-butyrolactone have difficulty in obtaining uniform and planar film at room temperature as they have slow evaporation rate. As an alternative, 2-methoxyethanol is a volatile and polar solvent, which is useful on a bar coating if applied using an air-blowing method with an air knife. Herein, a hot gas-blowing method for the fabrication of a perovskite layer to achieve both proper solvent evaporation and high crystallinity is developed. With 75 °C of N₂ blowing on the bar-coated perovskite solution, highly crystalline perovskite films with large grains without voids are fabricated, showing excellent optical and electrical characteristics, such as long carrier lifetime, few carrier recombinations, and low trap density. Both small-area solar cells and large-area modules show good performance, 20.85% for the solar cell and 15.4% for the solar module. The results indicate that the newly proposed method can equally be applied to the fabrication of large-area solar cells toward commercialization.