Boosting the photovoltage of dye-sensitized solar cells with thiolated gold nanoclusters

Glutathione-capped gold nanoclusters (Aux-GSH NCs) are anchored along with a sensitizing squaraine dye on a TiO2 surface to evaluate the cosensitizing role of Au(x)-GSH NCs in dye-sensitized solar cells (DSSCs). Photoelectrochemical measurements show an increase in the photoconversion efficiency of DSSCs when both sensitizers are present. The observed photoelectrochemical improvements in cosensitized DSSCs are more than additive effects as evident from the increase in photovoltage (ΔV as high as 0.24 V) when Au(x)-GSH NCs are present. Electron equilibration and accumulation within gold nanoclusters increase the quasi-Fermi level of TiO2 closer to the conduction band and thus decrease the photovoltage penalty. A similar beneficial role of gold nanoclusters toward boosting the V(oc) and enhancing the efficiency of Ru(II) polypyridyl complex-sensitized solar cells is also discussed.