Algal buffer layers for enhancing the efficiency of anthocyanins extracted from rose petals for natural dye-sensitized solar cell (DSSC)

Abstract

Summary Natural dye-sensitized solar cells (DSSCs) are becoming promising candidates for replacing synthetic dyes. Anthocyanins, a flavonoid pigment which is responsible for the coloration in fruits and flowers, have shown productive results in employing them as natural dye for DSSC. But unfortunately, they exhibit low efficiency compared with synthetic dyes. Probing the reasons for the low efficiency of anthocyanin paves way for finding solution to increase the efficiency. This paper lists the important factors that are responsible for anthocyanin instability in DSSC. As a remedial measure, this paper introduces two buffer layer made of algal byproducts—sodium alginate and Spirulina. Rutile phase TiO2 nanorods prepared by hydrothermal method were used as photoelectrode and are subsequently characterized by X ray diffraction, transmission electron microscopy, and optical studies. The use of sodium alginate above the photoelectrode has proved to improve the dye concentration in the film by introducing more hydroxyl groups on the surface of TiO2. Anthocyanins extracted from rose petals using citric acid as solvent were used as dye for DSSC. Prior to the sensitization process with anthocyanin dye, the TiO2 film (with sodium alginate) was sensitized with Spirulina. The chlorophylls, xanthophylls, phycocyanins, and amino acids present in Spirulina assist the anthocyanins to bond with TiO2 efficiently. This helps in enhancing the efficiency of anthocyanins of rose dye from 0.99% to 1.47%.