Lattice Strain Conversion Suppresses Ion Migration to Stabilize Wide-Bandgap Perovskite Solar Cells

High-performance, stable wide-bandgap perovskite solar cells (WBG-PSCs) are crucial for advancing the commercialization of perovskite photovoltaic technology. Nonetheless, intrinsic perovskite imperfections, caused by lattice strain and phase segregation, severely hindered the urgent advancement of efficient WBG-PSCs. These imperfections lead to detrimental non-radiative recombination, which limits device performance and accelerates device degradation. In this study, we incorporated 1,3-diaminopropane dihydroiodide (PDADI) into the perovskite surface, effectively mitigating residual strain and suppressing phase separation. Through this synergy, the device effectively suppresses the formation of PbI₂ and inactive phases, minimizes interfacial defect generation, and enhances both carrier lifetime and transport properties. Consequently, we developed the WBG-PSCs with a bandgap of 1.66 eV, achieving an impressive power conversion efficiency (PCE) of 22.40% with a high open-circuit voltage (V_OC) of 1.23 V. More importantly, these unencapsulated devices demonstrated excellent environmental stability, maintaining 90.25% of their initial PCE after 1,500 hours in an atmospheric environment with 35% relative humidity. This study provides a simple and effective strategy to improve the efficiency and stability of WBG-PSCs.