Properties of a Ru/Ti bilayered counter electrode in dye sensitized solar cells

A Ru/Ti bilayer to a flat glass substrate was applied as a counter electrode to improve the energy conversion efficiency of a dye-sensitized solar cell device with the structure of glass/FTO/blocking layer/TiO 2 /N719(dye)/electrolyte/(50 nm Ru-50 nm Ti)/glass. For comparison, a 100 nm-thick Ru counter electrode on a flat glass substrate was also prepared using the same method. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency and impedance, were characterized using a solar simulator and potentiostat. The phase of the bilayered films was examined by x-ray diffraction. The measured energy conversion efficiency of the dye-sensitized solar cell device with a Ru/Ti bilayer counter electrode was 2.40%. The efficiency was 1.48 times larger that of the dye-sensitized solar cell with the 100 nm Ru counter electrode. The new phase of RuTi led to a decrease in resistivity and an increase in catalytic activity. The interface resistance at the interface between the counter electrode and electrolyte decreased when Ru/Ti bilayer thin films were applied. This suggests that Ru/Ti bilayer thin films improve the efficiency of dye-sensitized solar cells.