Implementation of a Multi‐Functional‐Group Strategy for Enhanced Performance of Perovskite Solar Cells through the Incorporation of 3‐Amino‐4‐Phenylbutyric Acid Hydrochloride

Abstract Reducing the defect density of perovskite films during the crystallization process is critical in preparing high‐performance perovskite solar cells (PSCs). Here, a multi‐functional molecule, 3‐phenyl‐4‐aminobutyric acid hydrochloride (APH), with three functional groups including a benzene ring, ─NH 3 + and ─COOH, is added into the perovskite precursor solution to improve perovskite crystallization and device performance. The benzene ring increases the hydrophobicity of perovskites, while ─NH 3 + and ─COOH passivate defects related to I − and Pb 2+ , respectively. Consequently, the power conversion efficiency (PCE) of the optimal device increased to 24.65%. Additionally, an effective area of 1 cm 2 with a PCE of 22.45% is also prepared using APH as an additive. Furthermore, PSCs prepared with APH exhibit excellent stability by 87% initial PCE without encapsulation after exposure at room temperature under 25% humidity for 5000 h and retaining 70% of initial PCE after aging at 85 °C in an N 2 environment for 864 h.