Preparation and characterization of nanostructured S and Fe co-doped TiO2 thin film by ultrasonic-assisted spray pyrolysis method

Nanostructured TiO2 and S and Fe co-doped TiO2 thin films with high transparency were prepared on glass substrate through ultrasonic-assisted spray pyrolysis technique. The effects of doping on morphological, optical and structural properties of TiO2 were studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), photoluminescence spectroscopy, Raman spectroscopy, and UV-visible absorption spectroscopy techniques. Because of the high uniformity and monodispersity of the prepared thin films, they have high visible light transparency. All of the prepared thin films have anatase crystal structure, however, introduction of the dopants, especially S dopant, in the lattice of TiO2 creates some structural defects in the TiO2. Because of the presence of defects as charge trapping center in the structure of the doped TiO2samples, these thin films have lower electron–hole recombination rate than undoped TiO2. Furthermore, simultaneous doping of S and Fe considerably narrows the band gap energy of TiO2.