An efficient thiolate/disulfide redox couple based dye-sensitized solar cell with a graphene modified mesoscopic carbon counter electrode

Graphene sheet is used to modify mesoscopic carbon materials through electrostatic induced self-assembly and applied as a Pt-free counter electrode (CE) in a thiolate/disulfide redox couple based dye-sensitized solar cell (DSSC). The electrochemical characterization are carried out with Electrochemical impedance spectroscopy and Tafel polarization, which indicates that the catalytic activity of mesoscopic carbon CE is dramatically improved and the mass transport of the thiolate/disulfide redox couple in the pores of mesoscopic carbon electrode was accelerated via being modified with graphene. As a result, efficiency up to 6.55% is obtained, which is increased by 35% than that of the normal mesoscopic carbon CE. It could be expected that Pt-free graphene modified mesoscopic carbon materials promise tremendous potential for iodine-free DSSC.