Nanoscale Colloids Engineering for Minimizing Efficiency Loss in Scalable Perovskite Solar Cells

Perovskite solar cells (PSCs) have achieved significantly high power conversion efficiencies (PCEs), approaching the performance of silicon‐based solar cells. However, scaling up PSCs while maintaining high‐efficiency remains a significant challenge. Here, we report a negligible efficiency loss in scalable PSCs by formate anions stabilized colloids. The formate anions enhance the charge density on colloidal surfaces, strengthening electrostatic repulsion and preventing particle aggregation. This significantly reduces colloidal size to around 30 nm and promotes homogeneous nucleation, allowing the scalable fabrication of high‐quality perovskite thin films from a small area to mini module size in ambient air. As a result, PSCs achieved PCEs of 24.30% (1 cm 2 ) and 24.10% (12.6 cm 2 , 5 cm × 5 cm mini module), with negligible efficiency loss upon scaling. To the best of our knowledge, this represents the highest efficiency reported for mini‐modules. Most importantly, the encapsulated mini module retained 95% of their initial efficiency after 1000 h of operation at maximum power point tracking in ambient air.