Light matters: fabrication and investigation of optical and wetting properties of TiO2/SiO2 multilayer structure

Abstract

This research examines the fabrication and analysis of optical and wetting characteristics in a multilayered titania/silica structure. A five-layer system of alternating titania and silica was produced using sol-gel spin coating, with layer thicknesses of 152/550/158/252/252 nm. XRD analysis verified the anatase phase of TiO₂ layers, predominantly oriented along the (101) plane, while SiO₂ layers were found to be amorphous, which minimizes scattering losses and boosts UV reflectivity. FTIR spectroscopy confirmed successful layer integration, revealing distinct Ti-O-Ti and Si-O-Si bond features, as well as O-H stretching vibrations indicative of surface stability. Optical testing showed high reflectance exceeding 97% at 300 nm in the UV range and 100% at 625 nm in the near-infrared spectrum. These remarkable optical properties result from constructive interference due to the refractive index difference between TiO₂ (2.4) and SiO₂ (1.46) layers. Wetting analysis using a goniometer revealed a contact angle of 37°, demonstrating hydrophilic behavior that enhances self-cleaning properties and environmental durability. The combination of hydrophilicity and optical efficiency makes this multilayer coating suitable for various applications, including UV lasers, optical sensors, photolithography, solar energy systems, and outdoor optical devices. The study underscores the potential of TiO₂/SiO₂ multilayer systems as versatile and robust UV reflectors, combining advanced optical performance with environmental adaptability.