Structural characterization of Graphene Oxide and Reduced Graphene Oxide used as counter electrode in flexible DSSC

Abstract

Graphene oxide (GO) and reduced graphene oxide (RGO) were synthesized from commercial graphite GR5 type, using the oxidative exhaustive exfoliation method or Hummers process. The characterization of GO and RGO allows ensuring the successful oxidation and reduction processes. Thin films of these materials were prepared and their electric properties were checked. The sheet resistance for GO films was 0.028 k}}$W \mathbf{sq} ^{\mathbf{-1}}$on polyethylene terephthalate (PET) substrate, and 0.160 k}$W \mathbf{sq} ^{\mathbf{-1}}$on soda lime glass (SLG) substrate. When RGO was used sheet resistance response increase to 0.391 k}$W \mathbf{sq} ^{\mathbf{-1}}$on PET substrate and 0.413 k}$W \mathbf{sq} ^{\mathbf{-1}}$ on glass substrate. RGO and GO thin films were prepared by blade coating technique and used to prepare Dye Sensitized Solar Cells (DSSC) or Gr\{a}tzel cells acting as counter electrodes, being a ruthenium complex as dye and iodide-triiodide electrolyte as couple redox. In standard illumination conditions the efficiency was measured with different dye concentration. The best results were found for a dye sensitized solar cell device PET/GO, with photovoltaic performance (PV)}$h =$ 0.25% (one TDBR coat) and for a DSSC device PET/RGO}$h =$ 0.20% (three TDBR coats).