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

Abstract

The influence of pH during hydrolysis of titanium(IV) isopropoxide on the morphological and electronic properties of TiO2nanoparticles prepared by the sol-gel method is investigated and correlated to the photoelectrochemical parameters of dye-sensitized solar cells (DSCs) based on TiO2films. 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 TiO2obtained by alkaline hydrolysis is c.a. 27% higher than for the acid TiO2films. The combination of acid and alkaline TiO2nanoparticles 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 TiO2films applied before the mesoporous layer. DSCs employing photoanodes with 30 TiO2bilayers have shown efficiencies up to 12% higher than the nontreated photoanode ones. These results can be conveniently used to develop optimized synthetic procedures of TiO2nanoparticles for several dye-sensitized solar cell applications.

Inorganic Photochemistry and Solar Energy Harvesting: Current Developments and Challenges to Solar Fuel Production

“…Electron recombination on the surface of the conductive substrate (typically FTO) can also occur and can be successfully controlled by deposition of a compact underlayer [132]. The so-called blocking layers have been deposited by the layer-bylayer technique, a cost-effective technique that provides an unprecedented control of film thickness at molecular and nanometric scales by the sequential deposition of a large variety of materials [79,[133][134][135][136][137][138]. The use of this technique in photoinduced devices was recently reviewed by us [139].…”

Applications of Mesoporous Ordered Semiconductor Materials — Case Study of TiO2

“…Among the methodologies of synthesis, the methods of sol-gel and homogeneous precipitation best favor the control of morphology [58,72,73]. The term sol-gel involves several synthetic methodologies based on hydrolytic processes [19,20,59,74]. Hydrolysis and condensation reactions involving the precursor allows the formation of colloidal particles (sol) and subsequent formation of three-dimensional networks (gel).…”

Solar Radiation Applications

“…Among the methodologies of synthesis, the methods of sol-gel and homogeneous precipitation best favor the control of morphology [58,72,73]. The term sol-gel involves several synthetic methodologies based on hydrolytic processes [19,20,59,74]. Hydrolysis and condensation reactions involving the precursor allows the formation of colloidal particles (sol) and subsequent formation of three-dimensional networks (gel).…”