Characteristics and Analyses of Various Counter Electrodes Applied in Quasi-Solid Electrolyte Dye-Sensitized Solar Cells

Abstract

A carbon-based counter electrode applied in quasi-solid-state dye-sensitized cell was demonstrated. For comparison, gel/quasi-solid-state dye-sensitized cells with a platinum-based counter electrode were also investigated. Performances and electrochemical properties of solar cells were evaluated by using a solar cell measurement system and an electrochemical impendences spectrometer. As the results shown for carbon-based quasi-solid-state dye-sensitized solar cells, the power conversion efficiency, short-circuit current density, open-circuit voltage, and fill factor are 3.55%, 11.79 mA/cm2, 0.69 V, and 43.79%, respectively. The charge transfer resistance of Rct1 at the electrolyte/counter-electrode interface was increased because of the Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer which can decrease the mobility of I3− ions. The charge transfer resistance of Rct2 at the TiO2/dye/electrolyte interface was decreased with the addition of PVDF-HFP polymer and TiO2 nanoparticles, due to the Ti+ cations assorting on the high fluorine electronegative polymer surface, and I− and I3− ions hopping in the channels formed in the polymeric phase by an electrostatic force. As the results of cell stability test shown, a better sealing method was suggested, because there were no pinholes at the counter electrode, the electrolyte would not leak from the hole by volatilization.