Fabrication and Properties of Graphene Electron Multiple Transporting Layers for Dye-Sensitized Solar Cell

To investigate the optimal working electrode for dye-sensitized solar cells (DSSCs), the traditional TiO 2 film is modified by adding an electron transporting layer of graphene. Different layers of TiO 2 /graphene/TiO 2 stacks on the FTO substrate are analyzed. The experimental results show that the TiO 2 /graphene/ TiO 2 /graphene/TiO 2 (TGT2) structure has higher dye loading, which means that more dye molecules can increase the light absorption. In the electrochemical impedance spectroscopy (EIS) analysis, the TGT2 structure has a lower interfacial resistance ( R ct2 ) of 2.35 Ω at the TiO 2 /dye/electrolyte interface and a higher electron lifetime (τ e ) of 64.28 ms. This result represents that the graphene material exerts its properties of good conductivity and high charge carrier mobility to reduce the interfacial resistance and enhance the electron transport capability. The DSSCs with TGT2 structure working electrode has the short circuit current density ( J SC ) of 10.87 mA/cm 2 and photovoltaic conversion efficiency (η) of 4.47%. In this study, the working electrode of DSSC is successfully modified by using a TGT2 structure, with an improved efficiency of 10.6% and short circuit current density ( J SC ) of 17.7% higher than that of the TiO 2 working electrode.