In Situ Polymerization of Cross‐Linked Perovskite–Polymer Composites for Highly Stable and Efficient Perovskite Solar Cells

Abstract Mixed‐halide perovskites have emerged as outstanding light absorbers that enable the fabrication of efficient solar cells; however, their instability hinders the commercialization of such systems. Grain‐boundary (GB) defects and lattice tensile strain are critical intrinsic‐instability factors in polycrystalline perovskite films. In this study, the light‐induced cross‐linking of acrylamide (Am) monomers with non‐crystalline perovskite films is used to fabricate highly efficient and stable perovskite solar cells (PSCs). The Am monomers induce the preferred crystal orientation in the polycrystalline perovskite films, enlarge the perovskite grain size, and cross‐link the perovskite grains. Additionally, the liquid properties of Am effectively releases lattice strain during perovskite‐film crystallization. The cross‐linked interfacial layer functions as an airtight wall that protects the perovskite film from water corrosion. Devices fabricated using the proposed strategy show an excellent power conversion efficiency (PCE) of 24.45% with an open‐circuit voltage ( V OC ) of 1.199 V, which, to date, is the highest V OC reported for hybrid PSCs with electron transport layers (ETLs) comprised of TiO 2 . Large‐area PSC modules fabricated using the proposed strategy show a power conversion efficiency of 20.31% (with a high fill factor of 77.1%) over an active area of 33 cm 2 , with excellent storage stability.