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 cm2 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.