Ultraviolet-visible absorbance analysis on solvent dependent effect of tropical plant anthocyanin extraction for dye-sensitized solar cells

Abstract

In the current investigation, natural tropical dyes extracted from Mulberry, Roselle and Oxalis Triangularis were used as natural dye sensitiser. Four different extraction solvents, namely acetone, ethanol, a mixture of acetone and ethanol (v/v 1:2) and distilled water were employed to extract natural anthocyanin dyes from Mulberry, Roselle and Oxalis Triangularis. The natural dye extraction process was analysed using ultraviolet-visible spectroscopy, and the spectrum was taken in the wavelength range of 400 nm to 800 nm. The main photoactive component of Mulberry, Roselle and Oxalis Triangularis are anthocyanins compound which considered as an unstable pigment that undergo gradual degradation processes throughout storage or use. The spectra can be seen, that there are differences in its intensity where ethanol and acetone solvent was much higher absorbance peak vis-à-vis the other solvents. Mulberry and Roselle extraction in ethanol shows the high absorbance intensity at wavelength 550 nm, while Oxalis Triangularis extraction in acetone shows the higher absorbance at the peak of 664 nm. This indicates the presence of more anthocyanins compound that absorbs a higher number of photon energy light source. It is also appears that the dye extraction performance gradually degrade after seven days storage in dark condition. Mulberry and Oxalis Triangularis extraction in mixture of acetone and ethanol exhibit low degradation percentage about, 0% and 32%, respectively, while Roselle extraction in DI water reveal 0% degradation after 7 days.