Dye-Sensitized Solar Cells Made with TiO₂-Coated Multi-Wall Carbon Nanotubes and Natural Dyes Extracted from Ipomoea

Abstract

This paper reports the fabrication of photoelectrode of dye-sensitized solar cells (DSSCs) using TiO₂-modified multi-wall carbon nanotubes (MWCNTs). The self-developed nanofluid synthesis system is employed to make TiO₂ nanofluid which has good roundness and uniform size, at an average particle size of 40 nm. The self-prepared TiO₂ nanoparticles, after being mixed with TiO₂-nanoparticle-modified MWCNTs (TiO₂-CNT) by sol-gel method, are deposited in an indium tin oxide (ITO) conductive glass by electrophoretic deposition method, thus forming a thin film of TiO₂/CNTs of 14 μm thick. As seen from the FE-SEM image and Raman spectra, the CNTs adhere well to the TiO₂ nanoparticles. In addition, the developed DSSCs make use of the natural dye extracted from ipomoea. The TiO₂-nanoparticle-modified MWCNTs prepared by sol-gel method can improve the performance of DSSCs by increasing the short-circuit current density (J_sc). The enhancement of J_sc is attributed to the increased adsorption area of thin films and the improved interconnectivity among TiO₂ particles and TiO₂-CNTs. Experimental results show that TiO₂-modified MWCNTs prepared using natural dye extracted from ipomoea could enhance the light-to-electricity efficiency of DSSCs by as high as 30% (0.278% to 0.359%).