Self‐Assembled Monolayers for Perovskite‐Based Tandem Solar Cells

ABSTRACT Perovskite tandem solar cells (TSCs) are pivotal for breaking the single‐junction Shockley–Queisser limit and enabling low‐cost, high‐efficiency photovoltaics. Self‐assembled monolayers (SAMs) have become indispensable in this pursuit, due to their attractive capability of forming lossless contact at the interface that can effectively suppress non‐radiative recombination. Their role has evolved rapidly from a hole transport layer in wide‐bandgap subcells to a multifunctional component across narrow‐bandgap perovskite, organic, and interconnecting layers, proving critical for record‐efficiency devices. This review provides a systematical assessment of the synthesis and properties of SAMs, as well as their transformative impact on all‐perovskite, perovskite‐organic, perovskite‐Si, and perovskite‐CIGS TSCs. We conclude by identifying the key challenges and outlining a strategic roadmap for the future development of SAMs in tandem photovoltaics.