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International Journal of Photoenergy
Volume 2012, Article ID 638571, 7 pages
Research Article

Influence of the Sol-Gel pH Process and Compact Film on the Efficiency of T i O 𝟐 -Based Dye-Sensitized Solar Cells

1Laboratory of Photochemistry and Energy Conversion (USP), Instituto de QuĂ­mica, Universidade de SĂŁo Paulo, Avenue Prof. Lineu Prestes 748, 05508-900 SĂŁo Paulo, SP, Brazil
2Instituto de Química, Universidade Federal de Uberlândia 38400-902 Uberlândia, MG, Brazil
3Departamento de QuĂ­mica, Universidade Federal de Minas Gerais 31270-010 Belo Horizonte, MG, Brazil
4Departamento de FĂ­sica, Universidade Federal de Minas Gerais 31270-010 Belo Horizonte, MG, Brazil

Received 2 December 2011; Revised 27 January 2012; Accepted 27 January 2012

Academic Editor: Leonardo Palmisano

Copyright © 2012 A. O. T. Patrocinio 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.


The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and electronic properties of TiO2 nanoparticles prepared by the sol-gel method is investigated and correlated to the photoelectrochemical parameters of dye-sensitized solar cells (DSCs) based on TiO2 films. Nanoparticles prepared under acid pH exhibit smaller particle size and higher surface area, which result in higher dye loadings and better short-circuit current densities than DSCs based on alkaline TiO2-processed films. On the other hand, the product of charge collection and separation quantum yields in films with TiO2 obtained by alkaline hydrolysis is c.a. 27% higher than for the acid TiO2 films. The combination of acid and alkaline TiO2 nanoparticles as mesoporous layer in DSCs results in a synergic effect with overall efficiencies up to 6.3%, which is better than the results found for devices employing one of the nanoparticles separately. These distinct nanoparticles can be also combined by using the layer-by-layer technique (LbL) to prepare compact TiO2 films applied before the mesoporous layer. DSCs employing photoanodes with 30 TiO2 bilayers have shown efficiencies up to 12% higher than the nontreated photoanode ones. These results can be conveniently used to develop optimized synthetic procedures of TiO2 nanoparticles for several dye-sensitized solar cell applications.