Novel agarose polymer electrolyte for quasi-solid state dye-sensitized solar cell

Abstract

Quasi-solid state dye-sensitized solar cells (DSSCs) are fabricated with a novel polysaccharide gel electrolyte composed of agarose in 1-methyl-2-pyrrolidinone (NMP) as polymer matrix, lithium iodide (LiI)/iodine (I 2) as redox couple and titania nanoparticles as fillers. The polysaccharide electrolyte with different agarose concentrations (1-5 wt %) and various inorganic filler TiO 2 concentrations (0-10 wt %) are studied systematically by differential scanning calorimetry (DSC) and the AC impedance spectra. The electrochemical and photoelectric performances of DSSCs with these electrolytes are also investigated. It is found that increasing agarose and inorganic filler concentration leads to a decrease in T g in the range of 1-2 wt % for agarose and 0-2.5 wt % for TiO 2 changed electrolytes, which results in high conductivity in these electrolytes. From the electrochemical analysis, it is observed that the electron lifetime in TiO 2 of DSSCs increases with agarose, while decreases with inorganic filler contents. The prolonged electron lifetime in DSSCs is advantageous to improve open-circuit voltage (V oc). Based on these results, the cell with the electrolyte of 2 wt % agarose shows the optimized energy conversion efficiency of 4.14%. The optimized efficiency of the DSSC with added titania is 4.74% at 2.5 wt % titania concentration.