Recent Advances of Quasi‐Two‐Dimensional Perovskite Solar Cells

Quasi‐two‐dimensional (quasi‐2D) perovskites are promising materials for next‐generation photovoltaics, offering significantly improved moisture and thermal stability over conventional three‐dimensional (3D) perovskites. However, their intrinsic multiple‐quantum‐well structure and the inclusion of bulky insulating organic cations severely hinder charge‐carrier transport, interlayer charge transfer, and phase purity, resulting in power conversion efficiencies that still lag substantially behind those of 3D counterparts. This review systematically analyzes the structural and optoelectronic properties of key quasi‐2D perovskite systems, including the Ruddlesden–Popper, Dion–Jacobson, and alternating‐cation‐in‐the‐interlayer phases. It then outlines the persistent challenges in realizing high‐performance devices, focusing particularly on crystallographic orientation control and phase distribution regulation. Recent advances in performance optimization are comprehensively reviewed, encompassing compositional engineering, intermediate‐phase manipulation, solvent and additive strategies, interfacial modification, and advanced deposition techniques, with corresponding mechanistic insights provided. Finally, current limitations are critically evaluated, and future research directions toward rational molecular design and scalable manufacturing are proposed to advance the practical deployment of efficient and stable quasi‐2D perovskite solar cells.