Morphological, structural, electronic and optical properties of deposited 4d-Mo doped TiO2 thin films compared to first-principles calculations

Abstract

The present work reports the theoretical and experimental studies of structural, the electronic and optical properties of the TiO2 and Mo-doped TiO2 thin film. The linearized enhanced plane wave full potential (FP-LAPW) approach based on the density functional theory (DFT) has been used to theoretically examine structural, the electronic, and optical properties of molybdenum-doped TiO2 for various Mo concentrations (2 %, 4 %, 6 %). The band gap value is enhanced substantially, so it remains comparable to the experimental value of 3.00 eV and the Fermi level of MTO shifts downward in the valence band. This shift is originated mainly from the Mo-3p states, with a minor contribution by the Ti-3d and O-2p states. Undoped and Mo-doped TiO2 films were synthesized using the sol-gel spin coating technique as an experimental approach. The spectra obtained through X-ray Diffraction (XRD) indicated the presence of both anatase and rutile phases with no additional secondary phases detected. Scanning electron microscopy (SEM) analysis indicated that the thin films consisted of spherical, homogeneous nanoparticles that decreased in size as the Mo doping level increased. In addition, the transmittance spectrum showed a dip near 380 nm, consistent with the optical band gap, showing that the TiO2 films are absorbing in both the UV and visible domains. The band gap of the Mo doped TiO2 was reduced from ∼3.38 eV to ∼3.19 eV with an increase in Mo doping percentage.