Effect of electrolyte redox potentials on the photovoltaic performance in dye-sensitized solar cells based on porphyrin dye
We have investigated the effect of two different kinds of cobalt electrolytes on the photovoltaic performance in dye-sensitized solar cells (DSSCs) using the established porphyrin dye (YD-2). We have characterized the photovoltaic performance of DSSCs containing iodide/triiodide and two different Co3+/2+ electrolytes to confirm the relationship between redox potential of cobalt(III/II) tris(2,2′-bipridine), [Co(bpy)3]3+/2+, cobalt(III/II) tris(1,10-phenanthroline), [Co(phen)3]3+/2+ and the photovoltaic characteristics in DSSCs. Compared to the iodine-based electrolyte, the photovoltage of the DSSCs based on [Co(phen)3]3+/2+ was increased by 15%. The current densities in [Co(bpy)3]3+/2+ and [Co(phen)3]3+/2+-based devices decrease due to their larger size and decrease in difference bewteen HOMO level of dye and redox potential of electrolytes.