Betalain and anthocyanin dye-sensitized solar cells

In the present work, the mechanism behind the functioning of the eco-friendly dye-sensitized solar cell was explored. Dye-sensitized solar cells were fabricated using natural dyes extracted from common pear (Opuntia dillenii) and red tamarind (Tamarindus indica), and 1:1 mixture. Betalain and anthocyanin were identified as the main pigments that sensitize the semiconductor TiO2 film. The best conversion efficiency of 0.47 % was achieved from betalain dyes and 0.14 % from anthocyanin dye-sensitized solar cell [under standard Air Mass 1.5 illumination (85 mW cm(-2))]. The mixture of dye (1:1 mixture) adsorbed onto TiO2 exhibited an efficiency of 0.20 %. The light absorption behavior of extracted dyes was studied using ultraviolet-visible analysis. The influence of the binding nature of the dyes with TiO2 surface on the efficiency of the solar cells was analyzed through Fourier transform infra-red analysis. The electrochemical impedance spectroscopy was used to find out the internal charge transfer resistance of the cells. The device incident photon-to-current efficiency was obtained from 5 to 25 % for different natural dyes and found to coincide with the photocurrent-voltage characteristics and electrochemical impedance spectroscopy analysis.