Decoupling Photoinduced Lattice Evolution via Grain Spatial Isolation for Perovskite Solar Cells

Abstract

Abstract The long‐term operational stability of perovskite solar cells (PSCs) remains a major challenge, particularly due to photomechanical instability caused by light‐induced lattice dynamics. In this study, an in situ polymerization strategy is developed using the monomer 2‐acrylamido‐2‐methylpropanesulfonate (AMPS), which polymerizes during the annealing process of perovskite films to form a soft, cross‐linked polymer (P‐AMPS). The polymer acts as a grain boundary spacer, enabling physical spatial isolation between perovskite grains. This structure effectively mitigates light‐induced lattice expansion and stress/strain accumulation, while suppressing ion migration and strain‐induced defect evolution. Systematic experimental and theoretical investigations demonstrate that P‐AMPS enhances film quality and lattice integrity, while significantly improving the photomechanical stability of perovskite film. Methylamine‐free PSC fabricated using this approach achieved a power conversion efficiency of 25.78%. Following the ISOS‐L‐1 protocol, the P‐AMPS‐based device retained 83.52% of its initial maximum power point efficiency after 1500 h of continuous illumination. The grain spatial isolation strategy based on in situ polymerization offers a novel design concept for the commercialization of PSCs.