Defect Passivation and Stability Enhancement in Perovskite Solar Cells for Tandem Devices Using 2D Materials: A Review

Perovskite solar cells (PSCs) have revolutionized photovoltaics thanks to their tunable bandgaps and high power‐conversion efficiencies. Wide‐bandgap PSCs (WBG PSCs) are key candidates for high‐efficiency tandem photovoltaics, offering tunable bandgaps and the potential to surpass the Shockley–Queisser limit. However, practical deployment is hindered by defect‐mediated nonradiative recombination, phase instability, halide migration, and environmental degradation. This review systematically examines the integration of two‐dimensional (2D) materials to address these challenges, emphasizing defect passivation, charge‐carrier management, and interfacial engineering. Advances in inverted PSC architectures, including crystallization dynamics, passivation strategies, and interlayer design for selective charge transfer, are analyzed. Scalable fabrication methods such as vacuum deposition, one‐ and two‐step solution routes, and epitaxial growth are evaluated for their impact on device performance, reproducibility, and upscaling. Applications of 2D‐enhanced PSCs are surveyed, covering artificial indoor lighting, economic and environmental considerations, and integration into tandem solar cells with narrow‐ and wide‐bandgap components. Particular attention is given to front cells for WBG perovskites, interfacial engineering in all‐inorganic systems, and strategies to suppress deep‐level traps and ion migration. Finally, future research directions are discussed, highlighting the design of stable 2D/interface layers to achieve durable, high‐performance WBG inverted PSCs.