Philippe Thevenin

Our TiO 2 thin films were elaborated using spray pyrolysis technique. The spray solutions were prepared by two titanium precursors: titanium (IV) propoxide and titanium chloride. The elaborated thin films were analyzed with different characterization techniques such as X‐ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV–visible spectroscopy. These characterizations showed that the change of precursors from titanium chloride to titanium propoxide has a significant impact on all TiO 2 properties. The structural characterizations showed the formation of anatase TiO 2 and the crystallization improvement when the precursor changed from titanium chloride to titanium (IV) propoxide, which proves the superiority of our TiO 2 thin layers made without any type of annealing in comparison with other previous studies. The SEM images showed an improvement of the surface quality of the TiO 2 thin layers with the change of TiO 2 precursors' solution. The obtained optical properties confirmed the semiconducting properties of TiO 2 prepared by titanium propoxide with a large band gap equal to 3.28 eV and shifted to 3.18 eV. The refractive index increases from ~1.75 to ~2.14, while the porosity decreases. To confirm the experimental results, the Wien2K code, founded on the full‐potential linearized augmented plane wave (FP‐LAPW), has been used. The theoretical study has been done by applying the generalized gradient approximation (GGA), the modified Beck‐Johnson (MBJ) exchange potential, and the local spin density approximation + Hubbard's parameter U (LSDA + U). The theoretical results varied with the variation of approximations. The obtained properties were improved with LSDA + U and acquired the real values of Eg, n, and k for anatase TiO 2 (like Eg = 3.214 eV). The obtained experimental and theoretical results could be considered superposable or better than other ones recently published.