The ZnO/quantum dots with mixed natural dyes system for Dye-sensitized solar cells

Abstract

This work aims to study the effect of natural dyes and quantum dots on performance of dye sensitized solar cells (DSSCs). ZnO was used as a semiconductor and photoanode that was fabricated by the doctor blade method. The yellow cotton, red orchid, spirulina and indigo were used as a sensitizer. For optical properties of dyes, the maximum absorption wavelength of red orchid, spirulina, indigo and yellow cotton extract was 519, 620, 626 and 488 nm which were obtained from pelargonidin, c-phycocyanin, indigo and quercetin, respectively. Then the conversion efficiency was obtained. It was found that indigo showed the highest conversion efficiency equaled to 0.0200%. Then the method that dyes used to adsorb on ZnO was investigated. The results indicated that the dyes exhibited pseudo-second-order model for kinetic study. Moreover, both the Langmuir and the Langmuir and the Freundlich model were used for an isothermal study. In order to enhance the conversion efficiency, the mixed dyes and QDs were chosen for a further study on optical properties and photovoltaic performance. The results illustrated that the absorption and emission intensities increased with the dipping time of QDs. For mixed dyes systems, it was found that the use of a combination of yellow cotton-spirulina resulted in the DSSC with the highest conversion efficiency value of 0.0145% by varying the dipping time of producing QDs on ZnO, it was found that the ZnO/CdS, prepared by using the dipping time of 9 min showed the highest conversion efficiency of 0.0345%.