The Future of Using Earth-Abundant Elements in Counter Electrodes for Dye-Sensitized Solar Cells

With limited global resources for many of the elements that are found in some of the most common renewable energy technologies, there is a growing need to use "Earth-abundant" elements as a long-term solution to growing energy demands. The dye-sensitized solar cell has the potential to produce low-cost renewable energy, with inexpensive production and most components using Earth-abundant elements. However, the most commonly used material for the cell counter electrode (CE) is platinum, an extremely expensive and rare element. A selection of the materials investigated as alternative CEs are discussed, including metal sulfides, oxides, carbides, and nitrides and carbon-based materials such as carbon nanotubes, graphene, and conductive polymers. As well as having the potential for lower cost, these materials can also produce more-efficient devices due to their high surface area and catalytic activity. Therefore, once issues such as stability have been studied in more detail and scale-up of production methods are considered, there is a very promising future for the replacement of Pt in DSSCs with lower-cost, Earth-abundant alternatives. A wide range of alternative materials to replace the expensive and rare platinum in counter electrodes for dye-sensitized solar cells have been investigated, aiming to facilitate the large-scale production of such devices at low cost. The performance of a selection of these materials is summarized to give an overview of the range of material types investigated, and their potential for future implementation.