Characteristics of Dye-sensitized Solar Cells using Linear Sulfones as an Electrolyte Solvent

We evaluated linear sulfones as an electrolyte solvent used for dye-sensitized solar cells (DSC). A comparison of the effects of the structure of linear sulfones found that ethylisopropylsulfone (EiPS), which has low viscosity and high relative permittivity, exhibits the highest conversion efficiency. Next, we studied the effects of LiI and N-methylbenzimidazole (NMBI), common additives, on EiPS electrolytic solutions. As a result, we found that, unlike nitrile-based or ionic liquid-based electrolytic solutions, EiPS electrolytic solutions exhibit a high open-circuit voltage (Voc) even when no basic additive is added. We also found that the addition of La causes the short-circuit current density (Jsc) to decrease. In other words, the optimum composition of an additive for a linear sulfone-based electrolytic solution differs from those for nitrile-based or ionic liquid-based electrolytic solutions. In addition, we found that EiPS electrolytic solutions without additives exhibit higher conversion efficiency than conventional electrolytic solutions with additives.