Properties of the nano-thick Cr/Pt bilayered catalytic layer employed dye sensitized solar cells

A Cr/Pt bilayered catalytic layer on a flat glass substrate is used as a counter electrode in order to improve the energy conversion efficiency of a dye-sensitized solar cell device with an effective structure area of 0.45 cm² glass/FTO/blocking layer/TiO₂/N719(dye)/electrolyte/50 nm Pt/50 nm Cr/glass. For comparison, 100 nm-thick Pt and Cr counter electrodes on flat glass substrates are also prepared using the same procedure. The sheet resistance is examined using a four-point probe. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency, and impedance, are characterized using a solar simulator and potentiostat. The phases of the bilayered films are examined using X-ray diffraction. Furthermore, the microstructure of the bilayered films is characterized via field emission electron microscopy. The measured energy conversion efficiencies of the dye-sensitized solar cell devices with only Pt and Cr/Pt bilayer counter electrodes are 4.60% and 6.68%, respectively. The interface resistance at the interface between the counter electrode and electrolyte decreases when a Cr/Pt bilayer thin film is applied. The new phases of Pt₃Cr enable an increase in the catalytic activity. This suggests that the Cr/Pt bilayer catalytic layers might improve the efficiency of dye-sensitized solar cells compared with the conventional Pt layers.