Enhancing the stability of air-processed perovskite solar cells through a self-healing polymer with dynamic molecular locks for grain boundary engineering

Self-healing polymers are widely used in perovskite solar cells (PSCs) to reduce mechanical damage to perovskite films during operation. However, the limited effective bonding between polymers and perovskites accelerates perovskite degradation, especially in a complete air atmosphere. Herein, a novel self-healing polymer with dynamic molecular locks is incorporated into the grain boundary to achieve multiple functions of all-air-processed perovskite solar cells. Impressively, the unique molecular locking structure of this polymer forms a strong interaction with perovskite, reducing ion migration under locked conditions. It is worth noting that the grain boundary cracks of the perovskite film can heal within 2 hours at ambient temperature. Density functional theory (DFT) calculations substantiate the bipyridine-Pb²⁺ coordination, while finite-element simulations demonstrate a significant reduction in residual stresses within the polymer-doped perovskite films, enabled by the dynamic molecular locking mechanism of the polymer. This application of self-healing polymers paves the way for improved stability of flexible PSCs under open-air conditions.