Dye Sensitized Solar Cells Based on Natural Dyes Extracted from Plant Roots

Abstract

The objectives of this thesis are to prepare dye sensitized solar cells (DSSCs) using titanium dioxide (TiO2) as a semiconducting layer based on six natural dyes extracted from plant roots which are purple carrot, carrot, beet, curcuma, kale and radish as sensitizers. Among the previous dyes, purple carrot showed the best efficiency. The performance of DSSCs sensitized by purple carrot is improved through: adjustment of the solution extraction temperature, studying the effect of pH on the extract solution, and finally the influence of pre and post-treatments of the fluorinated tin oxide (FTO) glass substrate and the TiO2 film using hydrochloric (HCl), phosphoric (H3PO4), and nitric (HNO3) acids. The results showed that an extracting temperature of 50°C could be used as an optimal value. The treatment of the dye solutions with acetic acid resulted in better performance in comparison with the hydrochloric acid treatment. The pre-treatment of the FTO with H3PO4 and the post-treatment of TiO2 with HNO3 resulted in improved efficiencies of 130% and 250% respectively for the DSSCs sensitized by purple carrot.