Investigation of Mechanisms of Enhanced Open-Circuit Photovoltage of Dye-Sensitized Solar Cells Based the Electrolyte Containing 1-Hexyl-3-Methylimidazolium Iodide

The open-circuit photovoltage is improved by adding 1-hexyl-3-methylimidazolium iodide (HMImI) into the electrolyte. To investigate the mechanisms of the increase of the open-circuit photovoltage, we take the Mott--Schottky analysis and time-resolved mid-infrared absorption spectroscopy to study the band edge movement of TiO₂ and the rate of back electron transfer, respectively. The results indicate that the negative shift of the conduction band of TiO₂ is a predominant factor to increase the open-circuit photovoltage for the electrolyte containing HMImI.