Fabrication and Characterization of N-Doped TiO 2 Photoanode-Based Dye-Sensitized Solar Cells

Abstract

Numerous studies have investigated the incorporation of transition metals such as Ag, Co, Mn, Zn, Cr, Nb, W, and Cu into TiO 2 to evaluate their optoelectronic properties. Previous research indicates that the introduction of transition metal ions into the TiO 2 lattice can effectively modulate various electronic characteristics, including band gap energy, Fermi level, d-electron configuration, and band positions. Moreover, studies have indicated that doping TiO 2 with non-metals like N, C, B, S, and F can reduce the band gap and enhance light absorption in the visible spectrum. Besides individual research on the metallic and non-metallic doping of TiO 2 , studies have focused on their combined co-doping in TiO 2 for solar cell applications. For example, DSSCs incorporating Cu/N and Cu/S co-doped TiO 2 demonstrated notable performance improvements. In this work, we present our investigation into the structural, morphological, and optical properties of N-doped TiO 2 nanomaterials. The properties of the synthesized nanoparticles were assessed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Visible spectroscopy. XRD data confirmed that both undoped and N-doped TiO 2 samples exhibit analogous peaks for anatase and rutile phases, indicating that nitrogen doping did not induce any TiO 2 phase transitions. SEM images of the pure and N-doped TiO 2 fabricated films depict a well-dispersed microstructure and a consistent grain distribution. Moreover, the band gap ( E g ) and Urbach ( E u ) energies were observed to be lower for the synthesized nanoparticles. The data indicated a decrease in E g energy with nitrogen doping.