Buried‐Interface Regulation of Crystallization and Charge Extraction in Perovskite Solar Cells

ABSTRACT In n–i–p perovskite solar cells, the SnO 2 /perovskite buried interface plays a decisive role in governing crystallization and charge extraction. Here, trisodium methylglycine diacetate (MGDA) is introduced onto SnO 2 to regulate precursor behavior during crystallization. Molecular‐dynamics simulations using PbI 2 ∙DMSO as a representative solvent‐coordinated lead‐iodide species show that MGDA increases interfacial precursor localization while restricting lateral motion and aggregation. This modified precursor state is accompanied by slower but more extended late‐stage growth/reorganization during thermal annealing, leading to larger grains, fewer buried‐interface voids, improved crystallinity, and lower residual tensile stress. The optimized devices deliver a power conversion efficiency of 25.50%, while 7 × 7 cm 2 rigid and 5 × 5 cm 2 flexible mini‐modules reach 22.49% and 17.38%, respectively, with improved ambient‐storage and thermal stability. These results reveal the link between interfacial precursor behavior, subsequent crystallization, and device performance, providing guidance for buried‐interface design in perovskite solar cells.