Carbon–ITO Composite Electrodes with Silver Leaf Current Collectors for Efficient Perovskite Solar Cells

Developing vacuum-free and potentially scalable top electrodes is essential for the practical deployment of perovskite solar cells (PSCs). Here, a hybrid carbon-based composite electrode is developed by incorporating carbon black and colloidal indium tin oxide (ITO) nanoparticles into a commercial carbon paste, followed by lamination of a silver (Ag) leaf as a highly conductive current collector. The resulting carbon-ITO/Ag architecture exhibits substantially improved electrical properties, achieving a low sheet resistance of 0.11 Ω sq-1 and a conductivity enhanced by approximately three orders of magnitude relative to pristine carbon electrodes. Morphological analysis reveals that carbon black improves particle packing and film compactness, while ITO colloids promote the formation of additional conductive pathways within the carbon network. When integrated into ambient-processed PSCs, the optimized electrodes deliver improved charge collection and reduced resistive losses, yielding a champion power conversion efficiency of 19.64%. In addition, the optimized CCB-ITO/Ag electrode, which forms a denser carbon network and more conformal contact with the Ag leaf current collector, maintained approximately 90% of its initial efficiency, compared with ∼85% for C-ITO/Ag, after 2000 h (∼83 days) of aging under continuous dark storage at 25 °C and 2% RH. Improved performance retention demonstrates the beneficial effect of the hybrid carbon architecture on electrode stability while preserving efficient charge transport. This hybrid carbon-ITO/Ag strategy provides a practical, vacuum-free route toward conductivity-enhanced carbon electrodes for high-performance PSCs and offers a promising platform for potentially scalable device fabrication.