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

In n-i-p perovskite solar cells, the SnO₂/perovskite buried interface plays a decisive role in governing crystallization and charge extraction. Here, trisodium methylglycine diacetate (MGDA) is introduced onto SnO₂ to regulate precursor behavior during crystallization. Molecular-dynamics simulations using PbI₂∙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 cm² rigid and 5 × 5 cm² 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.