Morphology and Performance Enhancement through the Strong Passivation Effect of Amphoteric Ions in Tin‐based Perovskite Solar Cells

Abstract

AbstractDespite the optoelectronic similarities between tin and lead halide perovskites, the performance of tin‐based perovskite solar cells remains far behind, with the highest reported efficiency to date being ≈14%. This is highly correlated to the instability of tin halide perovskite, as well as the rapid crystallization behavior in perovskite film formation. In this work, l‐Asparagine as a zwitterion plays a dual role in controlling the nucleation/crystallization process and improving the morphology of perovskite film. Furthermore, tin perovskites with l‐Asparagine show more favorable energy‐level matching, enhancing the charge extraction and minimizing the charge recombination, leading to an enhanced power conversion efficiency of 13.31% (from 10.54% without l‐Asparagine) with remarkable stability. These results are also in good agreement with the density functional theory calculations. This work not only provides a facile and efficient approach to controlling the crystallization and morphology of perovskite film but also offers guidelines for further improved performance of tin‐based perovskite electronic devices.