Cauliflower-like TiO2 rough spheres: Synthesis and applications in dye sensitized solar cells

A series of mesoporous TiO2 rough spheres of alterable surface morphologies and pore structures were produced by altering initial temperatures and structural directing agents, Pluronic P105 (EO37PO56EO37) or F68 (EO78PO30EO78) tri-block copolymers. The average pore size increased with increasing initial temperature and in direct proportion to the polymer chain length. Various formation mechanisms were investigated including nucleation, growth and conglomeration of the initial TiO2 particles. The morphologies of mesoporous TiO2 rough spheres were completely maintained after calcination at 450 °C for 30 min. For dye sensitized solar cells (DSSCs) applications, efficient light scattering was obtained with the double layer film composed of a transparent layer containing 20 nm particles and a scattering layer containing ∼275 nm TiO2 spheres. The rough TiO2 spheres increase the overall conversion efficiency of DSSCs by 20.8% compared to TiO2 smooth spheres, and reach 6.56%.