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International Journal of Photoenergy
Volume 2014, Article ID 834269, 9 pages
http://dx.doi.org/10.1155/2014/834269
Research Article

Equilibrium and Kinetic Aspects in the Sensitization of Monolayer Transparent TiO2 Thin Films with Porphyrin Dyes for DSSC Applications

Chemistry Unit, School of Science and Technology, University of Camerino, Via S. Agostino 1, 62032 Camerino, Italy

Received 24 October 2013; Accepted 4 December 2013; Published 2 January 2014

Academic Editor: JiaHong Pan

Copyright © 2014 Rita Giovannetti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Free base, Cu(II) and Zn(II) complexes of the 2,7,12,17-tetrapropionic acid of 3,8,13,18-tetramethyl-21H,23H porphyrin (CPI) in solution and bounded to transparent monolayer TiO2 nanoparticle films were studied to determine their adsorption on TiO2 surface, to measure the adsorption kinetics and isotherms, and to use the results obtained to optimize the preparation of DSSC photovoltaic cells. Adsorption studies were carried out on monolayer transparent TiO2 films of a known thickness. Langmuir and Frendlich adsorption constants of CPI-dyes on TiO2 monolayer surface have been calculated as a function of the equilibrium concentrations in the solutions. The amount of these adsorbed dyes showed the accordance with Langmuir isotherm. Kinetic data on the adsorption of dyes showed significantly better fits to pseudo-first-order model and the evaluated rate constants linearly increased with the grow of initial dye concentrations. The stoichiometry of the adsorption of CPI-dyes into TiO2 and the influence of presence of coadsorbent (chenodeoxycholic acid) have been established. The DSSC obtained in the similar conditions showed that the best efficiency can be obtained in the absence of coadsorbent with short and established immersion times.