Influence of photoanode architecture on light scattering mechanism and device performance of dye-sensitized solar cells using TiO₂ hollow cubes and nanoparticles

Herein, we report the impact of light scattering mechanism on photovoltaic and photoelectrochemical performance of dye-sensitized solar cell (DSC) devices composed of TiO₂ nanoparticles and hollow cubes. DSCs are designed by two different light scattering modes (i.e., mode I in form of single layer electrode containing nanoparticles and hollow cubes and mode II in the form of double layer electrode comprising active and scattering layers made of nanoparticles and mixtures of nanoparticles and hollow cubes, respectively). The synthesized anatase-TiO₂ hollow cubes (200–400 nm) and nanoparticles (15–30 nm) are employed to enhance the optical length and light harvesting of photoanodes, respectively. Although the charge transfer resistances at Pt/electrolyte (R_Pt) and TiO₂/dye/electrolyte (R_ct) interfaces are decreased by mode I, it is not an appropriate approach for efficiency improvement of the devices due to hindering electrolyte diffusion and decreasing fill factor. In contrast, the photovoltaic performances of DSCs designed by mode II are successfully enhanced due to remarkable decrease in R_Pt and R_ct. Not only mode II improves light scattering but also it makes a balance between electron transfer and dye sensitization, leading to an increase in cell efficiency up to 9.31% compared to 7.0% for the reference device composed of pure nanoparticles.