Atomically dense Sb₂O₃ interlayer for highly stable perovskite photovoltaic modules

Metal halide perovskite solar cells have achieved notable progress over the past 15 years. However, due to their ionic nature, they are vulnerable under an electric bias. This issue limits their application in solar modules under partial shade, which often occurs in real-world operation. Here we developed a van der Waals antimony oxide (Sb₂O₃) interlayer at the perovskite/electron transport layer interface using scalable thermal evaporation. Thanks to its two-dimensional molecular crystal structure, the interlayer forms an atomically compact physical barrier that effectively passivates trap states, suppresses interfacial ion migration and enhances electrical robustness. Devices featuring the Sb₂O₃ interlayer achieved a certified power conversion efficiency (PCE) of 27.3% and demonstrated a high reverse-bias resistance of −22.3 V. We demonstrate solar modules with an area of 62.37 cm² and a certified PCE of 23.1%. They retained 96.4% of their initial PCE after 1,000 h of maximum power point tracking at a temperature of 65 ± 5 °C. The modules also maintained 91.2% of their initial PCE after 1,510 h of a shading test at 65 ± 5 °C. Our strategy provides an effective approach for enhancing the reverse-bias stability of perovskite solar cells and paves the way for their practical application in photovoltaic modules.