Properties of the Cu/Pt bilayered counter electrode employed dye sensitized solar cells

In order to improve energy-conversion efficiency using a Cu/Pt bilayer on a flat-glass substrate of a counter electrode (CE), a 0.45 cm dye-sensitized solar-cell (DSSC) device (with glass/FTO/blocking layer/TiO₂/N719 (dye)/electrolyte/50 nm-Pt/50 nm-Cu/glass) was prepared. For comparison, 100-nm thick Cu and Pt CEs were also prepared on flat-glass substrates using the same method. The photovoltaic properties of the DSSC device, such as short-circuit current-density (Jsc), open-circuit voltage (Voc), fill factor (FF), energy-conversion efficiency (ECE), and impedance, were checked using a solar simulator and potentiostat. The sheet resistance was examined using a four point probe. The phases of the bi-layered films were exa'miried using X-ray diffraction. The measured energy-conversion efficiency of the DSSC devices with only Pt and Cu/Pt bilayer counter electrodes was 4.60% and 5.72%, respectively. The sheet resistance and interface (CE/electrolyte) resistance of a Cu/Pt bilayer were smaller than those of a Pt-only layer. The phases of the Cu/Pt bi-layered films were identified in pure Cu and Pt without any intermetallic layer. We concluded that the increase in the efficiency of DSSCs employing Cu/Pt, resulted from employing the low-resistive Cu layer.