Highly Improved Photocurrent Density and Efficiency of Perovskite Solar Cells via Inclined Fluorine Sputtering Process

Increase in incident light and surface modification of the charge transport layer are powerful routes to achieve high-performance efficiency of perovskite solar cells (PSCs) by improving the short-circuit current density (J(SC)) and charge transport characteristics, respectively. However, few techniques are studied to reduce reflection loss and simultaneously improve the electrical performance of the electron transport layer (ETL). Herein, an inclined fluorine (F) sputtering process to fabricate high-performance PSCs is proposed. The proposed process simultaneously implements the antireflection effect of F coating and the effect of F doping on a TiO2 ETL, which increases the amount of light transmitted into the PSC due to the extremely low refractive index (approximate to 1.39) and drastically improves the electrical properties of TiO2. Consequently, the J(SC) of the F coating and doping perovskite solar cell (F-PSC) increased from 25.05 to 26.01 mA cm(-2), and the power conversion efficiency increased from 24.17% to 25.30%. The unencapsulated F-PSC exhibits enhanced air stability after 900 h of exposure to ambient environment atmosphere (30% relative humidity, 25 degrees C under dark condition). The inclined F sputtering process in this study can become a universal method for PSCs from the development stage to commercialization in the future.