Quasi solid state dye - sensitized solar cells based on polyvinyl alcohol ( PVA ) electrolytes containing I − / I − 3 redox couple

Quasi solid state dye-sensitized solar cells (DSSCs) have been fabricated with electrolytes containing I−/I3 redox couple using 80 % hydrolyzed polyvinyl alcohol (PVA) doped with potassium iodide (KI) and a mixture of potassium iodide and tetrapropyl ammonium iodide (Pr4NI) salts. The quasi solid state gel polymer electrolytes were prepared using 1:1 ethylene carbonate (EC):propylene carbonate (PC) mixture. The solar cells have the structure of ITO/TiO2/N3-Dye/electrolyte/Pt/ITO. The conductivity of the electrolytes has been calculated from the bulk resistance value determined using the electrochemical impedance spectroscopy. The performance of the DSSCs has been studied by varying the concentration of the doping salts in the electrolyte and incident light intensity. The DSSC fabricated with the KI salt electrolyte containing 9.9 wt% PVA, 39.6 wt% EC, 39.6 wt% PC, 10.9 wt% KI(+I2) exhibited the best power conversion efficiency of 1.97 %. However, the DSSC with a double-salt electrolyte containing 9.9 wt% PVA: 39.6 wt% EC: 39.6 wt% PC: (6.5 wt% KI: 4.4 wt% Pr4NI) (+I2) exhibited a higher efficiency of 3.27% under 100 mW/cm2 light intensity. The efficiency of this cell increased to 4.59 % under dimmer light of intensity of 54 mW/cm2.