Self-Assembly in Thin-Film Photovoltaics: Advancing Energy Conversion through Tailored Nanostructures

Self-assembled monolayers (SAMs) have emerged as pivotal molecular tools for interface engineering in thin-film photovoltaic technologies, including perovskite solar cells (PSCs), dye-sensitized solar cells (DSSCs), organic photovoltaics (OPVs), and quantum dot photovoltaics (QDPVs). By enabling precise control over energy-level alignment, defect passivation, crystallization kinetics, and interfacial stability, SAMs significantly enhance both the efficiency and long-term durability of photovoltaic devices. This chapter presents a comprehensive review of the roles and mechanisms of SAMs in various solar cell architectures, emphasizing their impact on charge transport, light harvesting, and mitigation of ionic migration. In PSCs, SAMs modulate interfacial dipoles, promote large-grained film growth, and suppress nonradiative recombination, contributing to power conversion efficiencies exceeding 26%. In DSSCs and OPVs, SAMs optimize electrode interfaces and enable controlled phase separation, while in QDPVs, self-assembly facilitates the formation of dense, ordered nanocrystal superlattices for enhanced carrier transport. We also explore recent advances in tandem photovoltaic devices, where SAMs enable conformal coverage on textured substrates and play a critical role in bridging wide- and narrow-bandgap subcells. This work highlights the interdisciplinary potential of molecular self-assembly as a scalable and tunable strategy to overcome persistent limitations in next-generation solar technologies.