Consequently, the efficiency of the cell is determined by those three
parameters. Fig. 10 shows the trends of VOC and JSC with different contents
of RGO in the photoanodes.
For DSSCs, the VOC values are obtained as the difference between the
electrons' Fermi level in TiO2 under the illumination and the Nernst potential
of the redox couple in the electrolyte [35]. The VOC value of the
cells does not show drastic change with different amounts of RGO as
shown in Table 1. It means that the Fermi level in TiO2 does not shift
much after stirring with VC. Despite the fluctuations, the VOC stay
above 0.7 V in those low RGO concentrations (below 1.0 wt.%).