Surfactant-free synthesis of pure anatase TiO2nanorods suitable for dye-sensitized solar cells

Abstract

A non-aqueous, solvothermal method was applied to the synthesis of TiO₂ nanorods in pure anatase crystal phase using Ti(IV)-isopropoxide. The use of benzyl alcohol as both solvent and reactant was investigated in combination with the addition of acetic acid to the reaction mixture. Various values of the AcOH : Ti(OiPr)₄ molar ratio were realized in the synthesis and tested in order to obtain a significant dimensional and morphological control over the resulting TiO₂ nanostructures, as well as to devise a simple and scalable synthetic protocol. On the basis of the experimental results, a substantially modified version of the well-established “benzyl alcohol route” was then designed and developed. X-ray diffractometry and transmission electron microscopy revealed that monodisperse anatase nanorods having a length of about 13–17 nm and a diameter of 5 nm can be obtained when AcOH and Ti(OiPr)₄ are reacted in comparable proportions. Investigation of the characteristic parameters of dye-sensitized solar cells fabricated using the synthesized nanorods as photoanode revealed a power conversion efficiency of about 7.5% corresponding to an improvement of 28% with respect to a commercial spheroidal nanotitania (P25) based reference device.