Mesoporous titania nanocrystals prepared using hexadecylamine surfactant template: Crystallization progress monitoring, morphological characterization and application in dye-sensitized solar cells

Titania nanocrystals were prepared by a modified sol-gel synthesis using the hexadecylamine surfactant as template. The progress of the synthesis in terms of phase formation and size of nanoparticles was monitored by X-ray diffraction and micro-Raman spectroscopy. Both techniques confirmed the presence of small particles crystallized predominantly at the anatase structure. Nanocrystalline thin film electrodes were constructed using an aqueous paste prepared from the material without addition of any binder or surfactant and applied to glass substrates. After annealing at 450 degrees C in air, TEM, SEM and AFM microscopies have shown that the particles remain anatase, spherical with an average size of about 7 nm and significant agglomeration. Nitrogen adsorption-desorption measurements revealed that the porosity is characteristic of a mesoporous solid with a very large specific surface (BET) area of 134 m(2)/g. The films were able to adsorb a large amount of standard N719 dye, making them capable to act as efficient photoelectrodes in nanostructured solar cells. Thus, after cell assembly, an overall energy conversion efficiency (eta) as high as 4.1% was attained. This value was higher than that measured with standard Degussa P25 titania films (eta = 3.4%). (C) 2009 Elsevier Inc. All rights reserved.