Application of TiO2-graphene nanocomposites to photoanode of dye-sensitized solar cell

TiO2-GR nanocomposites with various weight ratios of GR were obtained and applied to fabrication of DSSCs. Three layers of nanocomposites covered on electrodes were superior to one or two layers. An appropriate GR content in a photoanode was favorable to more uniform dispersion of TiO2 nanoparticles, leading to increased amount of dye adsorption and absorbance of visible light. The path and time of electron transport were shortened, interfacial charge transfer was accelerated, recombination probability was lowered, and DSSC performance was thus enhanced. By contrast, excess GR caused nonuniform dispersion of TiO2 nanoparticles. The specific surface area and amount of dye adsorption were reduced, leading to degradation of photocurrent density and device efficiency. It has been demonstrated that the most appropriate ratio of GR was 0.005, giving rise to an efficiency 22% much higher than that of a standard DSSC.