Ameliorating Defects in Wide Bandgap Tin Perovskite Solar Cells Using Fluorinated Solvent and Hydrazide

Abstract Surface passivation with multifunctional molecules is an effective strategy to mitigate the defect and improve the performance and stability of perovskite solar cells (PSCs). Here, the fabrication of a wide bandgap‐PSC is reported with tin perovskite (WB‐Sn‐HP; bandgap: 1.68 eV), followed by molecular surface passivation using 4‐Fluoro‐benzohydrazide (F‐BHZ). WB‐Sn‐PSC has demonstrated a promising device efficiency of 11.14% with improved device stability. The key to enhancing device performance lies in the meticulous engineering of both surface and bulk properties of WB‐Sn‐HP film with F‐BHZ treatment as a consequence of stronger electrostatic potential and molecular interaction with hydrazine and carbonyl functionalities. A compact perovskite film and highly crystalline film growth results in a longer carrier lifetime and surface defect mitigation with the control of Sn²⁺ oxidation as supported by theoretical calculations. This work underlines the promising potential of chemical engineering to improve the device performance of WB‐Sn‐PSC and stability using multifunctional passivating molecules.