Synthesis and characterization of sol-gel derived TiO2 thin films: Effect of different pretreatment process

Abstract

Titanium dioxide (TiO2) thin films have been successfully synthesized deposited on glass substrates by the sol-gel dip-coating method through different pretreating processes, including heated at 100, 500°C, via freeze drying, microwave heating for 10 min and subsequently annealed at 500°C for 2 h. The as-synthesized TiO2 films were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM) and ultravioletvisible (UV-vis) absorption spectra analysis technology. The preparation of the precursor sols and TiO2 films were described in detail. Effects of 100, 500°C, freeze drying and microwave heating pretreatment on crystalline structure, surface morphology, roughness, particle size, optical property and electronic transition of TiO2 thin films have been primarily investigated. The XRD results demonstrate that the TiO2 films were well-crystallized and consisted of anatase TiO2 phase only with (101) plane. The average crystalline size is only about 15 nm at 100°C pretreatment and the absorption edge shifts to shorter wavelength comparing with that at 500°C, freeze drying and microwave heating pretreatment. Pretreatment process is important during the preparation of thin films and has obviously effect on the structure and optical property of TiO2 films due to the different heating mechanisms.