A high efficiency indoline-sensitized solar cell based on a nanocrystalline TiO(2) surface doped with copper

Dye-sensitized photoelectrochemical solar cells made from nanocrystalline films of TiO(2) doped with copper and sensitized with indoline 149 dye are found to have impressively higher efficiencies compared to equivalent cells made from undoped films. The surface concentration of copper atoms on the TiO(2) where this effect is optimized is nearly the same as the concentration of dye molecules on the TiO(2) surface. Copper doping shifts the flat-band potential of TiO(2) in the negative direction, which is favorable for increasing the open-circuit voltage of the cell. It is suggested that in addition to the linkage of the carboxylate ligand of the dye to the TiO(2) surface, moieties in the rhodanine rings of the dye coordinate to the copper atoms on the TiO(2) surface. The coordination of the dye to copper seems to have a positive influence on the efficiency of the cell.