Enhancing Wide-Bandgap Perovskite Solar Cells with Synergistic Surface and Bulk Passivation

Wide-bandgap (WBG) perovskite solar cells (PSCs) are crucial for high-efficiency tandem photovoltaics; however, their performance and stability remain challenged. This work demonstrates the dual passivation role of 4-fluorinated-phenylethylammonium iodide (F-PEAI) in WBG PSCs. Using physics-based modeling and Bayesian analysis of the current density–voltage ( J – V ) curves, we have demonstrated for the first time that it is possible to identify the role of the passivation, either bulk or surface, which is difficult to separate using experimental analysis. The F-PEAI penetrates the perovskite layer, reducing defects, suppressing halide segregation, and improving charge transport. This results in PSCs with champion power conversion efficiency (PCE) of 20.6% for F-PEAI-passivated perovskites with a bandgap of 1.7 eV and 1 cm 2 PSCs with a PCE of 18.24%. Unencapsulated F-PEAI-treated PSCs retain their initial PCE more stably after 1000 h under inert and thermal conditions. These results emphasize the collaborative use of Bayesian and experimental approaches in revealing the distinct roles of F-PEAI for more stable and efficient WBG PSCs.