Mesoporous titanium dioxide: sonochemical synthesis and application in dye-sensitized solar cells

A novel method for shortening the synthesis time of mesoporous TiO2 to 6 h is reported. Low-angle XRD and TEM showed that mesoporous TiO2 with short-r ange ordered structures was synthesized when octadecylamine was used as a s tructure-directing agent and when Ti(OPri)(4) was used as a precursor. The highest surface area (853 m(2) g(-1)) was obtained after extraction with a dilute solution of nitric acid. The material maintained a high surface area (467 m(2) g(-1)) after calcination at 350 degreesC, but the short-range or dered structures collapsed. XPS showed the interaction between TiO2 and oct adecylamine, while DSC, TGA, and FT-IR spectra showed the removal of octade cylamine by extraction and calcination. A mechanism for the fast formation of mesoporous TiO2 is proposed. It is attributed to the formation of mesopo rous material at high temperatures formed in the interface between the gas and bulk solutions resulting from ultrasound irradiation. Electrodes made f rom the mesoporous TiO2 were tested in a dye-sensitized solar cell. The sho rt-circuit photocurrent, open-circuit photovoltage and fill factor increase d with an increase in the sintering temperature, having a performance thres hold at 450 degreesC, showing that the more ordered structures are required for high solar cell conversion efficiencies.