Reducing Inter-grain Gaps to Stabilize the Outdoor Operation of Perovskite Solar Modules

The grain boundary voids and interfacial delamination driven by environmental stress constitute a critical issue that affects the long-term outdoor operational stability of perovskite solar cells. Here, we developed a grain boundary polymerization strategy using dimethyl itaconate (DMI) monomers to reduce the inter-grain gaps of perovskite film. The reduced inter-grain gaps effectively alleviate the bulk voids and interfacial delamination in the devices and inhibit mobile ion migration out of the perovskite layer. Consequently, we achieved power conversion efficiencies of 25.9% (25.24% certified) in 0.09 cm2 lab-scale cells and 19.2% in 30 cm × 30 cm industrial-scale solar modules. The encapsulated modules retained 93% and 94% of their initial efficiencies for 2000 and 3000 h in damp-heat conditions and at maximum power point tracking, respectively, representing one of the most stable industrial-scale solar modules reported to date. Importantly, these encapsulated modules exhibited steady power output over 25 days of outdoor operation, demonstrating their viability for practical real-world applications.