Reduced graphene oxide films as transparent counter-electrodes for dye-sensitized solar cells

Stand-alone graphene-based films were prepared from graphene oxide (GO) nanoplatelets and their use as counter-electrodes (CEs) in dye-sensitized solar cells (DSCs) was investigated. The graphene-based CEs were produced by spray deposition of GO and chemically reduced GO, followed by thermal annealing under an inert atmosphere. These GO-based CEs were shown to have similar transparency as a reference CE made of Pt. Consistent with impedance data from symmetrical half-cells, DSCs assembled with such GO-based CEs exhibited relative efficiencies of ca. 75% comparatively to the reference Pt CE. The possibility of obtaining transparent (transmittance higher than 80%) and reasonable catalytic films for DSCs (energy conversion efficiency of 2.64%) from GO nanoplatelets was demonstrated. The need for reduction of the graphene oxide nanoplatelets prior to deposition was not observed, allowing for a simplified CE manufacturing process. However, further work is still needed to equal or surpass the performance of Pt CEs.