Flexible counter electrodes with a composite carbon/metal nanowire/ polymer structure for use in dye-sensitized solar cells

This paper presents the fabrication of novel flexible counter electrodes for use in dye-sensitized solar cells (DSSCs). The conductive electrodes are composites formed from a carbon film deposited on layered metal nanowire (NW) and polyacrylate polymer substrates. The metal NW materials consist of single-layer silver NWs (AgNWs) and copper NWs (CuNWs), in addition to double-layer AgNW/CuNW and CuNW/AgNW configurations. The carbon films are deposited using three different coating methods. Detailed analyses demonstrate that the photovoltaic performances of DSSCs based on the as-prepared carbon/metal nanowire/polymer composite counter electrodes are affected by the processing of both the carbon layer and the metal NW layer, as well as the metal NW layer configuration. A highest DSSC efficiency of 4.39% is achieved for the counter electrode prepared with the carbon layer deposited by drop casting on the AgNW/polymer substrate. A DSSC based on a counter electrode fabricated with a modified CuNW layer having improved uniformity, density, and smoothness achieves a cell efficiency of 4.01%. The developed electrodes have the advantages of facile preparation and low cost, and the DSSC efficiency can be increased by improving the preparation process of the counter electrode.