Influence of Spin Coating Speed on Optical Properties of Spin-Coated TiO2 Thin Films

In this work, nanocrystalline TiO2 thin films have been prepared by the sol-gel spin coating method at different spin speeds. X-ray diffraction (XRD), Scanning electron microscopy, and UV–vis spectroscopy were used to investigate the structural and optical properties of the deposited thin films. After the deposition, the samples were annealed in the open air and under the microwave. The results showed an optical energy gap of 3.33-3.61 eV for direct transition for the samples annealed in the open air and 3.28-3.48 eV for samples annealed under the microwave. Indirect transition on the other hand stood at 3.99 eV for all the 3 samples annealed in open air and 3.84-3.91 eV for samples annealed under microwave respectively. This work has shown that annealing either in open air or in a microwave can influence the structural and optical properties of thin films of TiO2. Other optical parameters studied include optical transmittance, refractive index, reflectance, absorbance dielectric constants, etc.