Imperfections Immobilization and Regeneration in Perovskite with Redox-Active Supramolecular Assembly for Stable Solar Cells

Abstract

Imperfections in metal halide perovskites, such as those induced by light exposure or thermal stress, compromise device performance and stability. A key challenge is immobilizing volatile iodine produced by iodide oxidation and regenerating impurities like elemental lead and iodine. Here, we address this by integrating a redox-active supramolecular assembly of nickel octaethylporphyrin into perovskite film, functioning as both an immobilizer and redox shuttle. Decorated ethyl groups in porphyrin distorts the π ring, increasing the axial ligand adsorption capacity of central metal ion, while reducing intermolecular interactions and promoting iodine adsorption achieving a maximum uptake of 3.83 mg mg−1 to iodine. Adsorbed iodine transfers more electrons to Ni ions, leading to a weakened interaction within I−I bond and facilitating the production of iodide ions. Such a situation further enables selective oxidation of metallic lead defects to Pb2+. Porphyrin supramolecule facilitates hole transport across perovskite grain boundaries, leading to a champion device efficiency of 25.37 % for a 0.10 cm2 active area, outperforms the value of control device being 23.96 %. Modified devices without encapsulation exhibit significantly enhanced stability, maintaining over 90 % of its initial performance after 1,000 hours of continuous 1-sun illumination at maximum power point at 65 °C.