Cu-based multilayer transparent electrodes: A low-cost alternative to ITO electrodes in organic solar cells

Copper-based multilayer transparent electrodes (MTEs) consisting of a dielectric-metal-dielectric (DMD) structure are explored as a replacement for indium tin oxide (ITO) electrodes in an effort to realize truly low-cost organic solar cells (OSCs). The outer dielectric is shown to play an important role not only in tuning the optical properties of MTEs but also in improving the electrical characteristics of Cu layers, thus providing both high transmission and low sheet resistance. We demonstrate that devices with the optimized Cu-based MTEs can have power conversion efficiency that is as high as 87% of that of ITO-based conventional cells, despite the absorption by Cu in the visible spectrum.