Applications of self-assembled monolayers (SAMs) in perovskite tandem photovoltaics

Perovskite tandem solar cells represent a pivotal route to surpass the Shockley-Queisser efficiency limit of single-junction photovoltaics through complementary spectral utilization. However, interfacial energy-level mismatch and severe non-radiative recombination remain critical bottlenecks that restrict performance and stability. Self-assembled monolayers (SAMs) possess unique merits including precise regulation of interfacial energy alignment between the perovskite and charge transport layers and optimized charge transfer dynamics. When deployed in single-junction and tandem perovskite solar cells, SAMs effectively enhance both power conversion efficiency and operational stability. With the rapid advancement of SAM design and engineering, perovskite tandem devices have achieved remarkable performance breakthroughs and broader development prospects. This review summarizes the multifunctional roles of SAMs as efficient charge-selective layers and versatile interface modifiers in perovskite tandem solar cells. We focus on representative applications of SAMs in perovskite tandem solar cells and further discuss the key challenges and future research directions toward scalable, stable, and industrial-grade implementation.