Cu(I)-based delafossite compounds as photocathodes in p-type dye-sensitized solar cells

The research of p-type dye-sensitized solar cells (p-DSSCs) has attracted growing attention because of the potential for integration with conventional n-type DSSCs (n-DSSCs) into the more efficient tandem-DSSCs. However, to date the performance of p-DSSCs is lagging behind that of n-DSSCs. One main reason is the lack of optimal photocathode materials. This article reviews the most recent progress in utilizing Cu(I)-based delafossite compounds, CuMO2 (M = Al, Ga or Cr), as photocathodes in p-DSSCs. As alternative materials to the commonly used NiO, the CuMO2 compounds have their intrinsic advantages such as lower valence band edge, larger optical bandgap and higher conductivity. By providing an insight into these materials and their applications in p-DSSCs, this perspective aims to stimulate more exciting research in the development of p-DSSCs as well as of tandem-DSSCs.