Recent progress of two-dimensional Ruddlesden–Popper perovskites in solar cells

Two-dimensional (2D) perovskites, as an important part of organic–inorganic hybrid halide perovskite materials, have attracted increasing attention owing to their excellent stability, especially water resistance, and become a research hotspot in the field of perovskite solar cells (PSCs). This review mainly summarizes the application of 2D Ruddlesden–Popper (RP) perovskite materials based on different spacer cations in solar cells. First, we briefly introduce the structure and classification of 2D perovskite materials. Then, the research progress of 2D RP perovskite materials based on several typical spacer cations is discussed, mainly including the performance improvement strategy, surface passivation application, and mechanism research. Finally, we also briefly prospect the present challenges and future development direction of 2D RP PSCs.