Photovoltage Improvement for Dye-sensitized Solar Cells via Interhalogen Redox Mediators

In this study, we found that the open-circuit voltage (Voc) of dye-sensitized solar cells was improved by using interhalogen ions (XY2-; X, Y = I or Br) synthesized by mixing iodide and bromide redox couples. I- ions are important for obtaining a higher shortcircuit current (Jsc) in the bromine-based electrolyte. The charge transfer and diffusion resistances were determined by electrochemical impedance spectroscopy. The interhalogen redox mediators improved the photoenergy conversion efficiency (PCE) and achieved a high Voc of 0.91 V.