Employment of L‐Citrulline as an Effective Molecular Bridge for Regulating the Buried Interface of Perovskite Solar Cells to Achieve High Efficiency and Good Stability

Suppressing the defects from SnO2 and perovskite interface is essential for the fabrication of large‐area n‐i‐p perovskite solar cells (PSCs) with the needed lifetime and efficiency for commercialization. Here, we report the employment of L‐Citrulline (CIT), which has amino acid (‐COOH, ‐NH2) and urea (‐NH‐CO‐NH2) groups during SnO2 colloidal dispersion to function as a molecular bridge to modulate the SnO2/perovskite buried interface. The amino acid group can effectively coordinate with Sn4+ to passivate the oxygen vacancy defects of SnO2, and the urea group can interact with uncoordinated Pb2+ and I‐. These interactions not only improve the electron mobility of SnO2 but also facilitate the formation of larger grain‐size perovskite film. In addition, they can also inhibit the generation of excess PbI2 and the non‐photoactive δ phase to result in suppressed trap‐assisted non‐radiative recombination. Consequently, the incorporation of CIT helps achieve a champion power conversion efficiency (PCE) of 25.95% (0.07065 cm2) in PSC with improved shelf‐life/light soaking stability. When combined with an anti‐solvent‐free slot‐die coating technique in air, the solar modules (23.26 cm2) could achieve a PCE of 22.70%, which is among the highest PCE reported so far.