An investigation on the photoelectrochemical properties of dye-sensitized solar cells based on graphene–TiO2 composite photoanodes

The graphene–TiO 2 nanocomposite has been prepared by mixing graphene oxide (GO) and tetra- n -butyl titanate (TBT) followed by the facile hydrothermal process when the reduction of GO to reduced graphene oxide (RGO) and the hydrolysis of TBT to TiO 2 happen. Characterization of the graphene–TiO 2 nanostructures is investigated in detail by X-ray diffraction, scanning electron microscopy, transmission electron microscopy , and Raman spectroscopy . A dye-sensitized solar cell (DSSC) based on graphene–TiO 2 composite photoelectrode exhibits a high energy conversion efficiency of 4.28%, compared with a DSSC based on pure TiO 2 photoelectrode (3.11%), accompanied by an increment in both short-circuit photocurrent density and open-circuit voltage. The significant enhancement in performance of DSSC is investigated through intensity-modulated photovoltage spectroscopy, intensity-modulated photocurrent spectroscopy, and electrochemical impedance spectroscopy . It is found that the incorporation of two-dimensional graphene nanosheets in the TiO 2 electrodes is the key factor leading to the improved photogenerated electron transfer ability and reduced charge recombination.