Stabilize Perovskite Precursors and Inhibit Intermediates for High Performing Perovskite Solar Cells

Abstract Significant power conversion efficiency (PCEs) advancements have been made in perovskite solar cells (PSCs). However, the degraded precursor can severely affect the crystallinity and reproducibility of the films, and the stability of the perovskite precursor and the intermediate phases during film growth remains a considerable hurdle. Here the saccharin sodium (SacS) is introduced into the perovskite precursor. Benefiting from the electron‐rich sulfonyl (O═S═O) and carbonyl (C═O) groups, the SacS molecule formed a stable complex with lead(II) iodide (PbI 2 ) in the precursor, which retarded the degradation and colloidal aggregation of the precursor and suppresses the formation of unfavorable intermediate phases during film growth. The strong interaction reduces the surface energy of the nuclei and promotes the formation of larger‐sized nuclei, resulting in high‐quality films with vertical orientation. This approach significantly improves the power conversion efficiency (PCE) of the device to 24.8% and bolsters the long‐term stability.