Impact of Solvent Mixtures on Natural Dyes and TiO 2 Nanoparticles for Dye-Sensitized Solar Cells (DSSCs)

Abstract

Water, as an inorganic solvent, has traditionally been considered inefficient for dye extraction in dye-sensitized solar cells (DSSCs) due to its limited absorbance spectrum, weak bonding with semiconductor surfaces, and rapid dye degradation. Organic solvents like acetone, ethanol, and methanol are typically preferred for enhancing photo-conversion efficiency in DSSCs. This study explores the use of distilled water in combination with ethanol as an alternative solvent mixture to support the global push for low-cost, non-toxic, and eco-friendly DSSCs. Chlorophyll and anthocyanin dyes were extracted from neem leaves (Azadirachtaindica) and rosella flowers (Hibiscus sabdariffa) using distilled water and ethanol. Their absorbance properties were analyzed using UV-Vis spectroscopy, FTIR, and XRD. Among the eight dye samples, the N e + H w mixture showed the highest absorbance (3.5 au.) with peaks at 550 nm and 660 nm. FTIR analysis revealed a broad hydroxyl band and a C≡C triple bond trace at 2360 cm -1, indicating enhanced photon harvesting and improved electron transport for higher short-circuit current density. XRD analysis indicated increased crystallinity and a particle grain size of 126.89 nm when adsorbed on a TiO 2 -coated FTO substrate. These findings demonstrate enhanced DSSC performance, suggesting improved long-term stability and efficiency.