Size-tunable TiO2 nanorod microspheres synthesised via a one-pot solvothermal method and used as the scattering layer for dye-sensitized solar cells

Abstract

TiO₂ microspheres assembled by single crystalline rutile TiO₂ nanorods were synthesized by one-pot solvothermal treatment at 180 °C based on an aqueous–organic mixture solution containing n-hexane, distilled water, titanium n-butoxide and hydrochloric acid. The spheres had a radiative structure from the center, and their diameters were controlled in the range from 1 to 5 μm by adjusting the volume of the reactant water. Nitrogen adsorption–desorption isotherms showed that all the as-prepared microspheres had relatively high specific surface areas of about 50 m² g⁻¹. The 1 μm sized TiO₂ nanorod microspheres were fabricated as a scattering overlayer in DSSCs, leading to a remarkable improvement in the power conversion efficiency: 8.22% of the bi-layer DSSCs versus 7.00% for the reference cell made of a single-layer film prepared from nanocrystalline TiO₂. Such improvement was mainly attributed to the enhanced light harvesting and dye loading brought by the effective scattering centers.