AbstractThe fabrication of perovskite solar cells (PSCs) through blade coating is seen as one of the most viable paths toward commercialization. However, relative to the less scalable spin coating method, the blade coating process often results in more defective perovskite films with lower grain uniformity. Ion migration, facilitated by those elevated defect levels, is one of the main triggers of phase segregation and device instability. Here, we report a bifunctional molecule, p‐aminobenzoic acid (PABA), which enhances the barrier to ion migration, induces grain growth along the (100) facet, and promotes the formation of homogeneous perovskite films with fewer defects. As a result, PSCs with PABA achieved impressive power conversion efficiencies of 23.32% and 22.23% for devices with active areas of 0.1 cm² and 1 cm², respectively. Furthermore, these devices maintained 93.8% of their initial efficiencies after 1000 hours under 1‐sun illumination, 75 °C, and 10% relative humidity conditions.This article is protected by copyright. All rights reserved