Solvent dependent natural dye extraction and its sensitization effect for dye sensitized solar cells

In this study, we have evaluated the effect of various solvents for natural dye extraction and suitable sensitization of the same extracted dye on mesoporous TiO2 for dye sensitized solar Cell (DSSC) applications. Twelve different extraction solvents, namely, distilled water, ethanol, acetone, methanol, acetonitrile, dimethyl sulfoxide (DMSO), chloroform, n-hexane, ethyl acetate, toluene, dichloromethane (DCM) and isopropanol were employed to extract natural dyes from Arnica granatum (pomegranate) peels, Citrus reticulata (tangerine) peels and Parquetina nigrescens (African parquentina) leaf. The polar solvents like; distilled water, methanol and ethanol were found to perform best to extract betacyanin dye from Punica granatum peels while the non-polar solvents like; dichloromethane and chloroform extract the most carotenoid and chlorophyll from Citrus reticulata peels and Parquetina nigrescens leaf, respectively. The natural dye extraction process was analyzed using UV-vis and photoluminescence spectroscopy. Further the extracted dye sensitization over TiO2 was monitored with solvent dependent surface wettability chemistry using contact angle measurements. The best dye adsorption solvent was achieved from using distilled water, acetone and dichloromethane for Punica granatum, Citrus reticulata and Parquetina nigrescens dyes, respectively.