Sol-gel spin coating of ZnO thin films for hydrophobic and radiation resistant applications

There is a significant demand for coatings that can withstand radiation in nearly every region globally, particularly where glass furnishings are utilized. These coatings are capable of reflecting radiation from the solar spectrum while also functioning as self-cleaning surfaces that eliminate pollutants from the glass. Nonetheless, scientists are persistently investigating methods to cost-effectively manufacture these coatings for application across diverse industries. This study focuses on the effective production of Zinc Oxide (ZnO) thin films through sol-gel spin coating techniques, intended for application on glass surfaces. The goal is to enhance these surfaces with UV and IR reflection capabilities, alongside hydrophobic characteristics that repel water and promote a self-cleaning effect. The analysis via X-ray Diffractogram (XRD) demonstrated that the coating exhibited a hexagonal Wurtzite crystal structure of ZnO. The study conducted using Fourier Transform Infrared (FTIR) provided additional confirmation of the presence of Zn and O functional linkages at distinct wavenumbers, specifically 733 cm⁻¹ and 2896 cm⁻¹, respectively. Field emission scanning electron microscopy (FESEM) was employed to analyze the thickness of the ZnO layer. The findings indicated the development of a slender layer measuring around 46 nm in thickness. Elemental analysis utilizing EDAX validated the detection of Zinc and Oxygen, with Zinc representing 32% of the atomic weight percentage and Oxygen comprising 68%. Furthermore, the coatings’ resistance to radiation was evaluated through ultraviolet visible and near-infrared spectroscopy (UV-VIS-NIR). The findings indicated that a mere single layer of Zinc Oxide was capable of reflecting 50% of ultraviolet light and 45% of infrared light. After conducting experiments with a goniometer, it was observed that the ZnO coating (500 °C) demonstrated hydrophobic property when in contact with a water droplet, showing a contact angle of ~120°.