Perovskite Surface Treatment with Cu₂O‑MIL-53 (Al) Metal-Organic Frameworks for Enhanced Efficiency and Stable...

Defect formation in perovskite films, particularly due to uncontrolled lead iodide residues, remains a critical challenge in perovskite solar cells (PSCs), leading to nonradiative recombination, voltage losses, and rapid device degradation. Surface passivation is therefore essential to suppress recombination and enhance device stability. In this work, we introduce a simple surface modification strategy using Cu₂O-MIL-53-(Al) (CuM) nanoparticles, deposited by spin coating onto perovskite films. The incorporation of CuM effectively regulates residual PbI₂, promotes the reduction of the relative PbI₂-related diffraction contribution, and modifies the interfacial chemical environment. As a result, the optimized device achieved a power conversion efficiency (PCE) of 20.25% with an open-circuit voltage (V _oc) of 1.11 V and negligible hysteresis. Photophysical and electrochemical analyses further indicate reduced nonradiative recombination and improved interfacial carrier dynamics after CuM treatment. In addition, unencapsulated devices retained 96.56% of their initial efficiency after 1000 h under ambient humidity, and the CuM-treated device also exhibited improved thermal-storage stability at 65 °C under N₂. These results identify CuM surface treatment as an effective interfacial-engineering approach for improving the performance and storage stability of PSCs.