Improved durability of dye-sensitized solar cell with H2-reduced carbon counter electrode

Abstract

Carbon counter electrodes for dye-sensitized solar cells (DSSCs) have attracted strong attention due to their low material cost and practically high power conversion efficiency (PCE). However, there were issues in PCE stability observed during durability tests. In this study, H2-reduced carbon counter electrode for low cost DSSCs is introduced and demonstrated improved durability over the conventional carbon electrodes, with the absolute PCE value of 7.7%. It was found that carbon resistance decay ratio improved compared to those without H2-reduction process. These cells after the durability test were disassembled, and surface adsorptions on the carbon counter electrodes were analyzed. The adsorption of compounds originated from the dye and co-adsorbents on the H2-reduced carbon electrode was largely reduced, due to the cleaning of surface functional groups that can adsorb large molecules. These results suggest that H2-reduction process proposed in this work effectively reduces surface adsorptions on carbon electrode, and as a result improves the durability of DSSCs.