Rational Tailored Polyfluorosubstituted Amide Molecule for Stabilizing PbI₆ Framework and Inhibiting Ion Migration Toward Highly Efficient and Stable Perovskite Solar Cells

Abstract Perovskite solar cells (PSCs), while highly efficient, face stability challenges that hinder their commercial application. These instability issues mainly arise from the fragile nature of Pb─I bonds in perovskites, which easily break under environmental stresses such as heat and light, leading to the breakdown of the [PbI₆] framework and irreversible degradation. To address these issues, a multifunctional molecule, N¹,N⁴‐bis(2,3,5,6‐tetrafluoro‐4‐iodophenyl)terephthalamide (FIPh‐A), is designed and synthesized to enhance the stability of perovskite films and devices. FIPh‐A molecule possesses carbonyl, amino, and iodotetrafluorophenyl groups that bind and stabilize Pb²⁺ ions and [PbI₆]⁴⁻ octahedra structure, preventing ion migration in perovskite films. The activation energy of ion migration increases obviously from 0.28 eV to 0.39 eV by adding FIPh‐A verified by experiment results. The residual strain is also released efficiently by introducing FIPh‐A molecule into perovskite films characterized by grazing incidence X‐ray diffraction. The champion PSC with FIPh‐A achieves a power conversion efficiency of 24.60%. After 500 h of continuous illumination (ISOS‐L‐1) and 300 h of thermal aging at 80 °C (ISOS‐D‐2I), these PSCs with FIPh‐A maintained 93% and 77% of their initial efficiency, respectively. These results emphasize the potential of multifunctional additives in overcoming the stability challenges of PSCs, thereby facilitating their commercial advancement.