Reduced graphene oxide embedded titanium dioxide nanocomposite as novel photoanode material in natural dye-sensitized solar cells

Dye-sensitized solar cells were fabricated using the natural dye anthocyanin extracted from Nerium oleander, Ixora coccinea and Erythrina variegata flowers with sol-gel routed TiO2-reduced graphene oxide nanocomposite photoanode. X-ray diffraction analysis of TiO2-reduced graphene oxide nanocomposites proved the anatase phase titania. Scanning electron microscope analysis confirmed the incorporation of reduced graphene oxide in TiO2 matrix. Transmission electron microscopic analysis established the dispersion of reduced graphene oxide in TiO2 network. The influence of reduced graphene oxide on the band gap and life-time of electron-hole pair in TiO2-reduced graphene oxide nanocomposites was observed from ultra violet-visible and photoluminescence spectra respectively. Fourier transform infra-red analysis confirmed the expected interaction between TiO2 and reduced graphene oxide. An increase in electrical conductivity was observed in TiO2-redcued graphene oxide nanocomposites than the pristine TiO2. The optimized TiO2-redcued graphene oxide nanocomposite was used as an anode material in the construction of dye-sensitized solar cells and the performance was studied by photocurrent-voltage characteristics and electrochemical impedance spectroscopy. The solar cells with TiO2-redcued graphene oxide nanocomposite photo anode exhibited enhanced efficiency of 0.47-0.57%.