Vacuum Processability of Self-Assembled Monolayers and Their Chemical Interaction with Perovskite Interfaces

Self-assembled monolayers (SAMs) have gained significant attention as an interfacial engineering strategy for perovskite solar cells (PSCs) due to their efficient charge transport ability and work function tunability. While solution-based methods such as dip-coating and spin-coating are widely used for SAM deposition, challenges such as non-uniform coverage, solvent contamination, and limited control over molecular orientation hinder their scalability and reproducibility. In contrast, vacuum deposition techniques, including thermal evaporation, overcome these limitations by enabling the formation of highly uniform materials with precise control over thickness and molecular arrangement. Importantly, the chemical interactions between SAM materials and perovskite layers, including coordination bonding with Pb²⁺ ions, play an important role in passivating surface defects, modulating energy levels, and promoting uniform perovskite crystallization. These interactions not only enhance wettability but also improve the overall quality and stability of perovskite films. This review highlights the advantages of vacuum-deposited SAMs, promoting strong chemical interactions with perovskite layers and improving interfacial properties critical for scalable applications.