A single layer deposition of Li-doped mesoporous TiO₂ beads for low-cost and efficient dye-sensitized solar cells

Herein, we report a new strategy for improving the efficiency and reducing the fabrication cost of dye-sensitized solar cells (DSCs) by elimination of the three- or four-fold layer deposition of TiO2. This is performed by replacing a single layer deposition of mesoporous TiO2 beads, with sub-micrometer size, high surface area and tunable pore size, synthesized by a combination of sol–gel and solvothermal methods. Furthermore, superior electronic properties gained by a reduction in electronic trap states are achieved through doping of pristine TiO2 beads with lithium. The beads have a spherical shape with monodispersed texture consisting of anatase-TiO2 nanocrystals and ultra-fine pores. The outstanding light scattering and harvesting characteristics of the beads emerge from a combination of tailored morphology and crystal structures. These have resulted in a 40% increase in solar to electric power conversion efficiency, for a single spin-coated film without an additional scattering layer and pre- and post-treatment with TiCl4 solution, compared to the reference nanoparticulate TiO2 device.