Effect of Au nanoparticles added in nanocrystalline TiO2 film on the photoelectrode of dye-sensitised solar cells

In this study, we used a citrate reduction method and electrophoretic deposition (EPD) to prepare hybrid nanocrystalline TiO2/Au films and applied it to the photoelectrode of dye-sensitised solar cell. The films and solar cells were investigated by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), I-V characteristics and electrochemical impedance spectroscopy (EIS) analyses. In the FE-SEM analysis, TiO2/Au hybrid layers have the porous structure that is advantageous in the dye-loading capacity. The results of EDX reveal that the TiO2/Au hybrid layer contains 0.28 wt% gold nanoparticles. X-ray diffraction patterns show that the TiO2/Au hybrid films contain TiO2 anatase and rutile phase, and Au peaks. Under sunlight simulator (AM 1.5 100 mW/cm(2)) illumination, the conversion efficiency of dye-sensitised solar cell with TiO2/Au hybrid layer is obviously higher than that of TiO2 film. In the analysis of electrochemical impedance spectroscopy (EIS), the total impedance of hybrid TiO2/Au photoelectrode is 98.9 Omega, which is lower than that of TiO2 film photoelectrode. These results indicate that TiO2/Au hybrid layer can increase the conductivity and reduce the recombination of charges in the photoelectrode, resulting in the increase in conversion efficiency for DSSCs.