Fabrication of TiO2 photoelectrodes doped with copper and zirconium to improve electron generation and flow in dye-sensitized solar cell

Abstract

Dye-sensitized solar cell (DSSC) are devices that convert solar light into electricity using a semiconductor substance, e.g. TiO2. Although DSSC are environmentally friendly and economical, they exhibit a low energy conversion efficiency. In this study, to improve its energy conversion efficiency, a DSSC in which TiO2 was doped with transition metals (TMs) such as Cu and Zr was fabricated by a sol–gel method. Doping with TMs extended the light-absorption range of TiO2 to the visible-light region, generating more electrons and improving electrical conductivity. The successful doping of Cu, Zr in the fabricated photoelectrode was confirmed by X-ray diffraction (XRD) and FESEM–energy dispersive X-ray spectroscopy (EDS) analyses, and doping with Cu, Zr increased the dye adsorption amount and current density of DSSC. In addition, the electron-transfer resistance was confirmed to be reduced by electrochemical impedance spectroscopy (EIS) analysis, and the electron movement, speed, and lifetime were improved by Intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) analyses. The electrical properties of the Cu, Zr-doped TiO2 photoelectrodes were determined from the chemical capacitance and recombination resistance calculations, and the results revealed that the efficiency was improved by Cu, Zr doping. In conclusion, the Cu, Zr doping of the photoelectrode improved the electron generation and flow of TiO2, thereby increasing the energy conversion efficiency of the DSSC by up to 3.28%