Operational stability of efficient opto-electronic conversion is crucial for the success in large-scale application of perovskites devices. Owing to the intrinsically weak structure of perovskites, iodide represents the most volatile constituents, and its diffusion can induce irreversible degradation that continues to present a great challenge to realize stable perovskite devices, Here, we introduce a low-temperature processing strategy to increase the operational stability of high-efficiency perovskite solar modules by engineering low-dimensional diffusion barriers, reducing the unwanted interfacial diffusion of ions by 10(3)-10(7) times in magnitude. We finally achieved stable and efficient perovskite solar modules with an area of 36 cm(2) retaining over 95% of their initial efficiency of over 15% after 1,000 h of heating at 85 degrees C, and 91% after light soaking in AM 1.5 G solar light for 1,000 h, respectively. Our findings provide an effective strategy to realize operationally stable and efficient perovskite solar cell modules.