Fabrication and characterization of zinc nitrate doped TiO2 nanotubes for dye-sensitized solar cells

Zinc-doped titanium dioxide nanotubes were successfully synthesized, characterized, and tested as materials for energy conversion in dye-sensitized solar cells. The TiO₂ nanotubes were grown through single-face anodization at a constant direct current voltage of 50 V and room temperature on titanium sheets with a thickness of 0.25 mm and purity of 99.7%. The electrolyte was composed of ethylene glycol, ammonium fluoride (0.3% wt. NH₄F), and deionized water (2% v/v H₂O). The titania nanotubes were doped with Zn using Zn (NO₃)₂ as the dopant source. The molar ratios of zinc nitrate were varied from 1, 3, 5, and 7 mM. X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectroscopy (techniques were employed to characterize the Zn-doped titanium dioxide nanotubes. The samples were then tested in dye-sensitized solar cells, and their photoelectric conversion efficiencies were calculated. As a result, amorphous-TiO₂ structure was transformed into the crystalline anatase phase after annealing. The best performance was observed for the 5 mM zinc nitrate sample, with a photoelectric conversion efficiency of 4.96% and an energy band gap of 3.18 eV. The findings of this research provide valuable insights for ongoing and future studies in the development of renewable energy.