Improving the efficiency of dye sensitized solar cells by TiO2-graphene nanocomposite photoanode

• Composite photoanodes for DSSCs were prepared by simple addition of graphene micro-platelets to TiO2 nanoparticulate paste.
• Transmission electron microscope was used to confirm the presence of graphene in composite films after heating at 450 °C for 30 min.
• The cell with graphene/titania photoanode obtains a conversion efficiency of 4.03%.
• Which is increased by 26% compared to the cell with pristine titania electrode.
• DFT is used to find the band gap of TiO2 and GR-TiO2.

Nanocomposite photoanodes were prepared by addition of graphene (GR) micro-platelets to TiO2 nanoparticulate paste. TiO2/graphene based DSSCs were fabricated using Z907 photosensitizer. Transmission electron microscope was used to confirm the presence of graphene in composite films after heating at 450 °C for 30 min. UV-visible absorption spectroscopy, photocurrent–voltage characteristics and electrochemical impedance spectroscopic measurements were conducted to characterize the DSSCs. The results show that the photo conversion efficiency is highly dependent on the concentration of graphene in the photoanode. Under an optimal conditions, solar cell based on graphene/TiO2 shows power conversion efficiency (PCE) of 4.03%, which is about 26% greater than the cell based on pristine TiO2 electrode (3.20%). A density functional theory was used to compute the band gap of TiO2 and graphene-TiO2 nano clusters.