Omnidirectional SiO2 AR Coatings

Abstract

It is of great importance to develop antireflective (AR) coatings and techniques because improved optical performance has been progressively prerequisite for wide-ranging applications such as flat panel displays, optoelectronic devices or solar cells. Natural surroundings inspire researchers considerably to impersonate in order to provoke analogous characteristics via artificial approaches, which provide the opportunity for emerging techniques and development in material engineering. Herein, SiO2 antireflective (AR) coatings comprised of two layers were fabricated using a physical vapour deposition method via glancing angle. The top layer fabricated at an oblique angle of 80° and the bottom layer close to the substrate was deposited at a deposition angle of 0°. The experimental outcomes demonstrate that there is a slight influence on the refractive index of thin films by changing the morphology of nanostructures keeping deposition angles the same. The top layer shows a periodic arrangement of SiO2 nanostructures while the bottom stratum represents a SiO2 compact dense layer. The assembled bilayer SiO2 AR coating retains omnidirectional AR efficiency and tunability at a preferred wavelength range displaying <1% reflectance. Moreover, the fabricated omnidirectional SiO2 AR coatings have thermal stability up to 300 °C. These SiO2 AR coatings also possess negative temperature resistivity to withstand different cold storage conditions. Hence, the flexible and environmental adaptive SiO2 AR coating offers an intriguing route for imminent research in optics.