Optimization of anthocyanin extraction parameters from M. malabathricum via response surface methodology to produce natural sensitizer for dye sensitized solar cells

Abstract

The Box Behnken design has been employed to study the synergy between three extraction parameters, i.e. extraction temperature, soaking period and trifluoroacetic acid (TFA) concentration in methanol solvent. The response of colour lightness, L*, saturation, S and anthocyanin content in the extract (mg/L) on varying these parameters were examined. The optimum parameters obtained from this study are 0.5% TFA-99.5% methanol, soaking time of 132.43 min and the extraction temperature of 80 °C. These values have the highest desirability of 0.942 and resulted in the highest anthocyanin yield of 4596 mg/L. The extract containing anthocyanin obtained under the optimal conditions was further evaluated as a sensitizer for the dye sensitized solar cells. Maximum solar conversion efficiency of 1.05% was achieved. Additionally, the DSSC fabricated using the extract from Melastoma malabathricum to 100 mW/cm2 simulated sunlight resulted in a short circuit photocurrent density (Jsc) of 1.3 mA, open circuit voltage (Voc) of 616 mV, and a fill factor (FF) of 57%.