Widening spectral range of absorption using natural dyes: Applications in dye sensitized solar cell

Abstract

Dye-sensitized solar cells (DSSCs) which also called Gratzel cells are a novel type of solar cells. Their advantages are mainly due to low cost production, low energy payback time, flexibility, performance also at diffuse light and multicolor options. DSSCs become more and more interesting since huge variety of dyes including natural dyes can be used as light harvesting elements. Natural dyes are environmentally and economically superior to synthetic-based dyes because these are nontoxic and cheap. Different natural dyes and their mixture extracts have been prepared and used as sensitizers in the fabrication of dye-sensitized solar cells (DSSCs). The dyes have been extracted from plant leaves including lemon, parsley, spinach, hibiscus-rosa sinensis, pomegranate fruit and vegetable beetroot. This article showed the effect of single and mixture natural dyes on the DSSC performance. The single dyes extracted from parsley, lemon and spinach leaves chlorophyll and hibiscus-rosa sinensis, pomegranate juice anthocyanin and beetroot betalain. The dyes mixture was prepared by mixing from both chlorophyll & anthocyanin and chlorophyll & betalain. The absorption spectra of these dyes have been investigated by UV–VIS spectrophotometry. The dyes have shown absorption in broad range of the visible region (400–700 nm) of the solar spectrum and appreciable adsorption onto the semiconductor (TiO2) surface. The adsorption of the dyes mixture onto the TiO2 electrode has higher absorbance than single dye and improved the conversion efficiency of solar cell.