Interfacial Property Tuning Enables Copper Electrodes in High-Performance n–i–p Perovskite Solar Cells

Developing cost-effective metal electrodes is essential for reducing the overall cost of perovskite solar cells (PSCs). Although copper is highly conductive and economical, it is rarely used as a positive electrode in efficient n–i–p PSCs due to its unmatched Fermi level and low oxidation threshold. We report herein that modification for the inner surface of electrodes using mercaptopyridine-based molecules readily tunes the electronic and chemical properties of copper, which has been achieved by fine-tuning the substituents of mercaptopyridines. The systematic adjustment for the Fermi level and oxidation potential of copper facilitates interfacial hole extraction and enhances the oxidation resistance of copper electrodes, which enables pure copper electrodes to be used in high-performance n–i–p PSCs with different hole transport materials. The resulting PSCs with copper electrodes display excellent power conversion efficiency and long-term stability, even comparable to those of the gold electrodes, showing great potential in the manufacturing and commercialization of PSCs.