Simultaneous Regulation of Crystallization Kinetics and Sn²⁺ Oxidation Suppression via Moderate Brønsted Acid for Efficient Tin‐Based Perovskite Solar Cells

Abstract Tin (Sn)‐based perovskite solar cells (TPSCs) have garnered significant attention in the photovoltaic field due to their promising physicochemical properties. Strong Brønsted acids are demonstrated to be highly effective in regulating the crystallization kinetics, thereby reducing defect formation in Sn‐based perovskite films. However, their strong acidity increases the oxidative potential of DMSO solutions, accelerating undesirable Sn²⁺ oxidation. Herein, a graph‐convolutional neural network is utilized to rapidly screen common organic acids and identified ibuprofen (IPF), a molecule with moderate acidity as a suitable additive, achieving a delicate balance between regulating crystallization kinetics and mitigating Sn²⁺ oxidation. Moreover, IPF incorporation improves the morphology and crystallization of Sn‐based perovskites while optimizing their band alignment with functional layers, facilitating more efficient charge transport. As a result, TPSCs with IPF achieve an impressive PCE of 15.63%, with a substantial enhancement in V_OC from 0.78 to 0.94 V. Furthermore, the hydrophobic benzene ring and carbon chains in IPF enhance moisture resistance, contributing to enhanced long‐term stability, with TPSCs maintaining 90% of their initial efficiency after 850 h. This study highlights the critical role of precisely tailoring additive properties in precursor solution to obtain high‐quality perovskite films, advancing the development of more efficient and stable TPSCs.