Optimizing the design of broadband solar metamaterial absorbers based on titanium nitride nanorings [Invited]
Do T. Nga, Anh D. Phan, Vũ Đình Lãm, Trevon Badloe, Junsuk Rho
Abstract
We propose a design rule for broadband metamaterial absorbers and investigate their plasmonic properties under solar irradiation. The metamaterials consist of periodic arrays of titanium nitride (TiN) rings placed on an antireflective MgF 2 dielectric film on a TiN bottom layer. We simulate the absorption of our metamaterials and find the dependence of the optical spectrum on structural parameters. From this, we propose a simple rule to design the nanostructures with an average spectral absorptivity greater than 95% over the solar spectrum from 200 to 3000 nm. Particularly, we introduce, for the first time, metamaterial perfect absorbers that can be designed using two-layer structures instead of higher-layer structures as conventional and sandwich designs. Our study would pave the way for great potential applications in the fields of solar energy harvesters and photo-to-thermal converters.