Tailoring of extraction solvent of Ixora coccinea flower to enhance charge transport properties in dye-sensitized solar cells

Abstract

We have tailored the extraction solvent of natural anthocyanin pigments from Ixora coccinea flower to lower charge transport resistance and enhance effective electron diffusion coefficient as well as absorption properties in DSSC sensitization. Six different extraction solvents were used in this study, namely, absolute ethanol, 70 % ethanol, acetone, dimethyl formamide, dimethyl sulfoxide, and distilled water. Dimethyl formamide was found to be able to extract the most anthocyanins from the Ixora flower, followed by dimethyl sulfoxide, acetone, absolute ethanol, 70 % ethanol, and distilled water, respectively. Dye-sensitized solar cells were fabricated using these extracted dyes as sensitizers and the cell performances were measured and characterized. The dye-sensitized solar cell equipped with a dye sensitizer extracted in 70 % ethanol achieved the highest conversion efficiency (ɳ = 0.50 ± 0.04 %) owing to its highest electron diffusion coefficient and lowest transport resistance in the TiO2/dye/electrolyte interface. This was followed by the cell equipped a with dye sensitizer extracted in acetone (ɳ = 0.30 ± 0.04 %), absolute ethanol (ɳ = 0.27 ± 0.01 %), dimethyl formamide (ɳ = 0.17 ± 0.01 %), dimethyl sulfoxide (ɳ = 0.16 ± 0.01 %), and distilled water (ɳ = 0.09 ± 0.003 %) in conversion efficiency performances, respectively. This study provides an insight into the importance of choosing the right medium for both dye extraction as well as the favorable solvent medium for dye adsorption onto TiO2.