Preparation of TiO2/ZrO2 Composite as Photoanode of Ruthenium-Based Dye-Sensitized Solar Cells

Abstract

Photoanode of dye-sensitized solar cell (DSSC) is an inorganic semiconductor layer with a nanoporous structure that has a function as a charge carrier transport layer and dye storage. Oxide semiconductor material such as titanium dioxide (TiO2) is widely used as a photoanode because of its wide band gap (3.2 eV) and high active surface area (80 m2/g), but TiO2 has low electron diffusion with high recombination (electron-hole pair pairing). To improve the electron diffusion and reduce recombination, TiO2 was modified with zirconia (ZrO2). The synthesis process was carried out using sol-gel method with variations of ZrO2 concentrations at 5 mol%, 10 mol%, and 15 mol%. Composite of TiO2/ZrO2 was then applied as a photoanode of DSSC. XRF results show that in all variations of ZrO2, the composites of TiO2/ZrO2 has been formed. Based on the results of UV-Vis spectroscopy, it was shown that the energy gap of TiO2/ZrO2 decreased as the increasing of ZrO2 concentration. The current density-voltage measurement was done to investigate the effect of ZrO2 addition to the TiO2 photoanode using light irradiation with power intensity of 100 mW/cm2. There is an increasing of photocurrent from 1.63 mA/cm2 of DSSC with TiO2 photoanode to 2.79 mA/cm2 of DSSC with TiO2/ZrO2 10 mol% photoanode. The highest efficiency obtained from DSSC with TiO2/ZrO2 photoanode is 1.15%. It was found that the presence of ZrO2 in the composite of TiO2/ZrO2 increased electron transport and reduced charge recombination to improve the photocurrent of DSSC.