Enhancement of the absorption coefficient of cis-(NCS)(2) bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) dye in dye-sensitized solar cells by a silver island film

The absorption coefficient of the dye used in dye-sensitized solar cells is a major factor in the total energy efficiency of the cell. In this work, we increased the absorption coefficient of the dye cis-(NCS)(2) bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) used in such cells by having the dye adsorbed on silver islands. We studied the effect of the surface area of silver (per surface area of substrate) and the effect of dye concentration on this enhancement. This technique significantly enhanced the absorption coefficient of the Ru-dye for the metal-ligand charge-transfer transition, which generates electrons and holes in dye-sensitized solar cells. The enhancement ratio of the absorption was controlled by the amount of Ru-dye directly adsorbed on the silver islands. The absorption was enhanced by a factor of 149, which was achieved for a dye concentration of 3 x 10(-10) mol/cm(2) and an average surface area of silver island of 0.63 cm(2)/cm(2) of substrate. Such enhancement is expected to be useful in improving the electric energy conversion efficiency of dye-sensitized solar cells.