Journal Article

As a potent interfacial platform at the crossroads of molecular engineering and device physics, self-assembled monolayers (SAMs) have been demonstrated to enable molecular-level control over buried interfaces in perovskite solar cells (PSCs), whilst overcoming the intrinsic limitations of conventional charge transport layers (CTLs). Over the past two years, SAM-enabled interface engineering has supported further efficiency gains, with certified efficiencies exceeding 27% for PSCs and 34% for tandem solar cells (TSCs), even as year-on-year improvements have become more incremental. Accordingly, this review first outlines the structural components of SAMs and relates them to interfacial energetics, perovskite film formation, and non-radiative loss suppression. We then summarize SAM design strategies primarily from the perspective of molecular structure and anchoring chemistry, while also highlighting how molecular symmetry and asymmetry can affect interfacial energetics, growth kinetics, and device performance. We further summarize emerging implementation strategies, such as co-SAMs, pre- & post-treatments, and in situ formation of SAMs. Finally, this review outlines key challenges and future directions for SAM-based PSCs and TSCs in terms of scalable fabrication, long-term stability, and interface universality, aiming to provide design principles and inspiration for constructing highly efficient, stable, and scalable devices.