Chemical passivation and grain-boundary manipulation via in situ cross-linking strategy for scalable flexible perovskite solar cells

Flexible perovskite solar cells (f-PSCs) are considered the most promising candidates in portable power applications. However, high sensitivity of crystallization on the substrate and the intrinsic brittleness usually trade off the performance of f-PSCs. Herein, we introduced an initiator-free cross-linkable monomer (2,5-dioxopyrrolidin-1-yl) 5-(dithiolan-3-yl)pentanoate (FTA), which can chemically passivate defects and enable real-time fine regulation of crystallization. The resulting perovskite film exhibited higher crystallinity, enlarged grain size, and reduced dependence on the substrate. In addition, the cross-linked FTA [CL(FTA)] distributed along the grain boundaries effectively released the residual stress and securely bound the grains together. Consequently, the CL(FTA)-modified flexible PSCs achieved a record-breaking efficiency of 24.64% (certified 24.08%). Moreover, the scalable potential has been verified by the corresponding rigid and flexible modules, delivering impressive efficiencies of 19.53 and 17.13%, respectively. Furthermore, the optimized device demonstrated bending durability and improved operational stability, thereby advancing the progress of f-PSCs toward industrialization.