Transparent dielectric TiO2/SiO2 coatings for thermal shielding and self-cleaning applications

DOI: 10.48129/kjs.17787

Abstract

Economical fabrication of one-dimensional dielectric reflectors using the hybrid sol-gel spin coating process is significant compared to sophisticated chemical and physical vapor deposition techniques. In this work, we preferred the TiO₂ and SiO₂ materials to fabricate dielectric reflectors due to their high refractive index contrast and easy tailor-ability of the reflectance window in the spectral region of interest. Here, we fabricated the near-infrared reflectors composed of TiO₂/SiO₂ films with a minimum number of stacks to attain the constructive interference of incident light so that maximum reflectance can be assured in the specific spectral region. X-ray diffraction (XRD) studies of the monolayer TiO₂ and SiO₂ confirmed the existence of anatase-TiO₂ and amorphous-SiO₂ phases, respectively. The TiO₂ and SiO₂ films were found to have refractive indices of 2.6 and 1.5, respectively, as measured by spectroscopic ellipsometry.The field-emission scanning electron microscopy (FESEM) analysis evidenced the fabrication of 2.5 stacks of TiO₂/SiO₂ films (TiO₂/SiO₂)_2.5. The reflectance measurement revealed 100 percent reflection in the near-infrared region having its center wavelength of 833 nm. In addition, we have examined the water contact angle of the reflector ( 2.5 stacks) using the sessile drop technique and found its contact angle of 29.3^O_, which suggests its anti-fogging and self-cleaning applications.