A Sol-Gel Type of Electrolyte for a Dye-Sensitized Solar Cell: Attenuated Total Reflectance (ATR) Vibrational Spectra Studies

Gel electrolytes based on triethoxy silane with a covalently linked mid-poly (propylene glycol) chain (ICS-PPG) and an incorporated KI + I2 redox couple were prepared for use in a dye-sensitized photoelectrochemical cell (DSPEC). Infrared ATR spectra measurements of ICS-PPG and ICS-PPG/KI + I2 catalyzed with HCl or AcOH were performed and the changes to the vibrational bands of the solvent (EtOH), the urea groups and the SiOEt groups were used to correlate the hydrolyzing effect of HCl and AcOH, strengthening the interactions between urea groups during gelation and the evaporation of EtOH. The measurements of the I/U characteristics of the DSPEC with ICS-PPG/KI + I2/HCl and ICS-PPG/KI + I2/AcOH showed that the cell with the latter type of electrolyte exhibited a higher efficiency, which was related to the influence of indirect hydrolysis in the case of the AcOH catalyst. ATR spectra analysis confirmed the hydrolyzing effect of AcOH on ICS-PPG, which involved the anionic substitution of the acetyl radical.