Synthesis and characterization of photoanode of nanostructured tio sensitized by natural dyes2 for application in dssc

Abstract

Dye-sensitized solar cells (DSSC), which is a third generation solar cell, have been receiving much attention as a new alternative over to conventional p-n junction devices. The key difference of the DSSC over traditional single junction solar cells is the use of a dye, which broaden the absorption frequency of the wide band gap semiconductor and thereby increase the efficiency of the working electrode. The natural dyes as sensitizers are getting prime importance in recent years due to their availability, low cost and environmental friendliness. Moreover, absorption spectrum of the dye and their anchorage to the surface of the nanostructured TiO2 are important parameters related to the efficiency of the cell. In the present study we report the synthesis of nanoporous TiO2 thin film on chemically clean glass substrates by a simple sol–gel technique using titanium isopropoxide as the precursor. The as synthesized films were annealed at 100 °C and were characterised by UV-Vis absorption, X-ray diffraction (XRD) and scanning electron microscope (SEM) for the investigation of their optical, structural and morphological properties. Aqueous and alcoholic extracts of the natural dyes were prepared for the fabrication of TiO2 working electrode. The sensitization efficiency of the as fabricated photoelectrode or photoanode was investigated using UV-Vis spectroscopy. The effects of changing extraction temperature and extracting solvent are also investigated. The SEM analysis revealed that the as synthesized TiO2 thin film are mesoporous in nature and favourable for anchorage of the dye on it. The XRD of the films confirmed the presence of anatase structure in the film. In conclusion, we have investigated the electronic coupling and the light harvesting properties of natural-dye sensitized TiO2 thin film for the fabrication of photoanode for application in DSSC.