Optical and sensing properties of sol-gel derived vanadium pentoxide thin films with porous and dense structures

The sol-gel and spin-coating methods were used for deposition of thin transparent V₂O₅ films on optical glass substrates and silicon wafers. Different synthesis and deposition conditions, including synthesis temperatures and post-deposition annealing, were used aiming at obtaining transparent films with high refractive index and good optical quality. The surface morphology and structure of the films were studied by SEM and XRD. The optical properties (refractive index, extinction coefficient and optical band gap) and thickness of the V₂O₅ films were determined from their transmittance and reflectance spectra. The potential application of the films as building blocks of optical sensors was demonstrated by preparation of multilayered structures comprising both V₂O₅ and BEA-type zeolite films and testing their response towards acetone vapors.