Application of PACz-Based Self-Assembled Monolayer Materials in Efficient Perovskite Solar Cells

Due to the advantages of low interface resistance, high work function, and high stability, PACz family materials have developed rapidly in p-i-n structure perovskite solar cells (PSCs) in recent years. Numerous studies have shown that PSCs prepared on the basis of PACz family materials or their derivatives as hole transport layers (HTLs) generally exhibit superior performance compared to PSCs prepared on the basis of organic HTL PTAA and inorganic HTL NiO_x, especially in terms of stability, demonstrating unparalleled charm. Since the application of PACz-like molecule V1036 as a HTL in PSCs in 2018, research reports on high-performance PSCs based on the PACz family HTL have been widely disseminated. Currently, PSCs based on the PACz HTL exhibit a world record value of 26.7% power conversion efficiency (PCE), breaking the long-standing world record held by n-i-p-structured PSCs, indicating its great potential for application in PSCs. The main problem with using PACz as a HTL is that it exhibits poor wettability toward perovskite precursor solutions, is sensitive to the thickness of the HTL and the roughness of the substrate, has poor thermal stability, and lacks preparation methods, making it difficult to achieve large-area device fabrication. This review summarizes the outstanding achievements of PACz to date, describes the mechanism and unique properties of PACz in PSCs, and looks forward to the future development prospects of PACz.