Stabilizing Precursor Solutions via Anion‐π Interaction for Robust Production of Perovskite Solar Cells

ABSTRACT The chemical instability of perovskite precursor solutions remains a formidable barrier to the scalable manufacturing of perovskite solar cells. This degradation is primarily driven by a deleterious reaction cascade initiated by the deprotonation of organic cations during storage, leading to rapid compositional drift and film failure. Here, we demonstrate that the introduction of 1,3,5‐tris(trifluoromethyl)benzene effectively suppresses this deprotonation pathway through targeted anion‐ π interactions. By selectively anchoring halide anions within the electron‐deficient π ‐system of TTB, we successfully inhibit the initial aging step, thereby preserving the chemical stoichiometry and structural integrity of the precursor solution. A remarkable power conversion efficiency of 26.07% can be achieved for the conventional n‐i‐p structured perovskite solar cells fabricated with fresh TTB‐modified precursors. Notably, devices processed from TTB‐modified precursors aged for seven days under ambient conditions can reach an efficiency of 25.76% (i.e. 99% of those made with fresh solutions), while those fabricated from three‐month‐aged solutions retains 23.88% (i.e. 92% retention). This molecular regulation strategy provides a robust solution to the long‐standing challenge of precursor ageing, offering a critical prerequisite for the high‐throughput, reproducible manufacturing of high‐efficiency perovskite photovoltaics.