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 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 (VOC) of 1.23 V. More importantly, these unencapsulated devices demonstrated excellent environmental stability, maintaining 90.25% of their initial PCE after 1500 h 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.