Influence of the Sol-Gel pH Process and Compact Film on the Efficiency of TiO2-Based Dye-Sensitized Solar Cells

• Published in: International journal of photoenergy Vol. 2012; no. 2012; pp. 1 - 7
• Main Authors: Patrocinio, A. O. T., El-Bachá, A. S., Paniago, E. B., Paniago, R. M., Murakami Iha, N. Y.
• Format: Journal Article
• Language: English
• Published: Cairo, Egypt Hindawi Puplishing Corporation 01.01.2012; Hindawi Publishing Corporation; Hindawi Limited
• Subjects: Differential scanning calorimetry; Dyes; Nanoparticles; Photovoltaic cells; Semiconductors; Sol gel process; Solar cells; Solar energy; Thin films; Titanium dioxide
• ISSN: 1110-662X; 1687-529X
• DOI: 10.1155/2012/638571

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.