Synergistic Enhancement of Light Harvesting and Interfacial Defect Reduction Using Metal–Organic Frameworks for Efficient and Stable Perovskite Solar Cells

Perovskite solar cells (PSCs) employing a SnO2 electron transport layer (ETL) have consistently broken efficiency records over the past decade by developing new active materials and optimizing device structures. As a key functional layer of PSCs, the SnO2 ETL directly dictates the performance and stability of the entire device. However, the defect-induced recombination losses and the optical losses caused by suboptimal optical paths on the SnO2/perovskite interface remain major barriers to PSCs performance improvement. Therefore, from the perspective of interfacial engineering, this study designs and synthesizes a metal–organic framework (MOF) material based on tin sulfate (SnSO4) and 2-nitroterephthalic acid (NTA), namely, Sn-NTA, which combines the functions of regulating the incident optical path and passivating interface defects. The Sn-NTA nanocluster enhances light scattering at the SnO2/perovskite interface, thus increasing perovskite light absorption. Moreover, the mesoporous MOF with carboxyl groups templates the crystallization of the perovskite and enables the formation of a radial MOF/perovskite junction, accelerating charge transfer. As a result, devices based on Sn-NTA show significantly improved photovoltaic properties, achieving a high power conversion efficiency of 24.04%. This work not only provides a new method for preparing multifunctional MOF materials but also inspires future researchers to focus on the collaborative design of interface optical structures and defect termination.