Effects of environmentally benign solvents in the agarose gel electrolytes on dye-sensitized solar cells

The ionic agarose gel electrolytes are prepared by using environmental benign solvents and co-solvents to improve the agarose solubility and capacities of the additives for dye-sensitized solar cells. The effects of single solvents (dimethyl sulfoxide (DMSO), propylene carbonate (PC), propylene glycol, triethylene glycol, and tetraethylene glycol) and DMSO-based co-solvents are examined on the conductivities, diffusion coefficients of triiodide, and energy conversion efficiencies. The highest conductivity, 14.2 mS cm−1, and the highest diffusion coefficient of triiodide, 2.7 × 10−6 cm2 s−1, are achieved for the electrolyte containing the co-solvent of 80 vol.% PC and 20 vol.% DMSO. The environmental benign co-solvent such as DMSO/PC can significantly increase the conversion efficiency to 3.4% with agarose compared to pure MPII with agarose (1.4%), while retaining ∼80% of the energy conversion efficiencies of the reference cell without agarose under the illumination at AM 1.5, 100 mW cm−2.

► Environmental friendly gel electrolytes are made of agarose and low toxic solvents. ► Incompatible solvent is used in agarose gel by modifying the solubility by co-solvents. ► The performances of agarose gel were improved by single or organic co-solvents. ► Low toxic co-solvent, DMSO/PC, was utilized and the efficiency was improved.