Development of hydrophilic multilayer structures for energy saving window applications using sol-gel spin coating

Abstract

This study is centered on analyzing the microstructural and optical reflectivity properties of multilayers composed of dielectric titania and silica. The goal is to investigate their potential application as energy-efficient windows on glass surfaces in different modern building projects. Nevertheless, the creation of these coatings can be quite expensive due to their complex structure. This study focuses on the development of a cost-effective method to produce a multilayer structure made of titania and silica. This structure has the remarkable ability to reflect approximately 100 % of UV light and 70 % of infrared light, all achieved with just three layers. The X-ray diffraction (XRD) analysis was conducted to examine the crystallinity of the coatings. The results indicated the presence of an anatase phase, as evidenced by the Bragg angle of 25^O. Empirical support was obtained through the use of Fourier transform infrared spectroscopy (FTIR), which revealed the presence of functional bonds at specific wavenumbers. Titania and silica were identified at wave numbers of 596 cm⁻¹ and 1246 cm⁻¹, respectively. The FTIR investigation was further supported by energy dispersive spectrum analysis (EDAX), which verified the existence of titania and silica in the multilayer structure. Through the use of field emission scanning electron microscopy (FESEM), the analysis of the multilayer structure unveiled the existence of layers composed of titania, silica, and titania. These layers were found to have thicknesses of approximately 286 nm, 315 nm, and 222 nm, respectively. The coatings were analyzed for reflectance using a UV–VIS-NIR spectrophotometer, which showed a full reflection of 100 % in the far ultraviolet range and a reflection of 70 % in the infrared region. Furthermore, the analysis of the coatings’ wetting behavior with a contact angle meter revealed their hydrophilic nature, suggesting their potential use in self-cleaning applications.