Enhanced Photovoltaic Performance of FASnI₃‑Based Perovskite Solar Cells with Hydrazinium Chloride Coadditive

For the fabrication of efficient Sn-based perovskite solar cells (PSCs), deposition of uniform and pinhole-free perovskite films with low Sn⁴⁺ content remains a crucial factor. In this work, we present a coadditive engineering process by introduction of hydrazinium chloride (N₂H₅Cl) in a single precursor solvent system to fabricate FASnI₃ perovskite films. The successful integration of N₂H₅Cl results in reduced concentration of Sn⁴⁺ content by 20% in the FASnI₃ film leading to suppressed carrier recombination and pinhole-free uniform coverage. These remarkable improvements in the FASnI₃ film results in power conversion efficiency (PCE) of Sn-based PSC up to 5.4% due to a significant increase in open-circuit voltage. Moreover, the best PSC without encapsulation showed stable shelf life up to 1000 h while retaining 65% of its initial PCE.