Chemically-Modified 2D Covalent Organic Framework as an HTL Dopant for High-Performance, Stable, and Sustainable Perovskite Solar Cells and Modules

Despite significant advances in perovskite solar cells (PeSCs), the operational instability and susceptibility to Pb leakage of PeSCs severely limit their widespread application. To address these issues, this study investigates the effect of doping the Spiro-OMeTAD hole-transporting layer (HTL) with a chemically-modified 2D conjugated covalent organic framework (Tp-Azo-COF) on the photovoltaic performance and stability of PeSCs. Enriched with abundant carbonyl (C═O) groups and azo (N═N) nodes, Tp-Azo-COF has excellent chelation and adsorption capabilities, and experimental results confirm that Tp-Azo-COF effectively decreases Pb leakage and Li-ion migration, improving the environmental safety and operational stability of PeSCs. The optimized PeSCs (0.12 cm²) exhibit an efficiency of 24.25%, a new benchmark for COF-modified devices, and maintain robust performance in large-area modules (18 cm²) with an efficiency of 21.96%. Under accelerated aging tests, including continuous light irradiation at maximum power point tracking for 980 h, the module demonstrated exceptional durability, with near-100% efficiency retention. The COF doping strategy developed in this study significantly enhances operational stability and minimizes Pb leakage in PeSCs, paving the way for the sustainable, large-scale deployment of perovskite photovoltaics.