SAMs-Mediated Interfacial Revolution in Perovskite Photovoltaics: Rational Molecular Engineering, Mechanistic Decoding and Versatile Device Implementation

Perovskite solar cells (PSCs) have emerged as a research hotspot in photovoltaics owing to their high power conversion efficiency (PCE), low fabrication cost, and simple preparation processes. However, their commercialization remains constrained by interfacial defects, non-radiative recombination, and limited scalability. Self-assembled molecules (SAMs), as a critical interfacial engineering tool, can significantly enhance device performance through defect passivation, energy band alignment, and crystallization regulation. Following the main theme of “molecular design—mechanistic understanding—application expansion,” this review systematically summarizes the structure–property relationships between SAMs architecture (anchoring groups, connecting backbones, and terminal functional groups) and their interfacial regulation mechanisms, with a particular focus on the important role of SAMs uniformity in governing interfacial quality, charge carrier transport, and device stability. The article presents multi-scale characterization techniques for evaluating SAMs interfacial properties, reviews the application progress of SAMs in rigid devices, flexible devices, and large-area modules, and finally discusses their future expansion directions in emerging fields such as tandem solar cells, flexible electronics.