Surfactant-free synthesis of pure anatase TiO2 nanorods suitable for dye-sensitized solar cells

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.