Mixed Dimensionality with a TiO₂ Nanostructure and Carbon Nanotubes for the Photoelectrode in Dye-Sensitized Solar Cells

In dye-sensitized solar cells (DSCs), TiO₂ nanoparticles (TNPs) were conventionally used as a photoelectrode. The photoelectrode has shown electron scattering problem. TiO₂ nanofibers (TNFs) and carbon nanotubes (CNTs), which have one dimensional structure, high surface area, good electrical, and catalytic properties, is expected to be able to greatly improve the performances of DSCs. To decrease the photoelectron scattering and electron–hole pair recombination in the TNP photoelectrode, electrospun TNFs and multi-wall CNT were added in TNP paste. The diameters of TNFs and multi-wall CNTs were ~400 nm and ~20 nm, respectively. The short circuit current and power conversion efficiency were increased by adding TNFs and decreased by adding CNTs. In DSCs with 15 wt% TNF, best values of 12.92 mA/cm² and 4.79% were observed and electron life time was 0.09 sec.