Self-Assembled Monolayer: Revolutionizing p-i-n Perovskite Solar Cells

Self-assembled monolayers (SAMs) have emerged as a transformative class of hole transport materials for inverted perovskite solar cells (PSCs), distinguished by their negligible parasitic absorption, solution-processable simplicity, and record-breaking device efficiencies. However, challenges still remain such as solvent-induced molecular aggregation, interfacial energy mismatch, and operational stability limitations, which originate fundamentally from insufficient mechanistic understanding of transparent conductive oxides (TCOs)-SAM-perovskite interactions. This review systematically traces the evolution of SAMs, explores their molecular-level functionalities, and examines their self-assembly mechanisms and diverse applications in PSCs. We clarify how molecular structures influence device performance and stability, highlighting SAMs' dual role in efficiency enhancement and durability improvement. Finally, we propose targeted research directions to address current limitations and accelerate the scalable application of SAM-based PSCs.