Ultra-broadband solar absorber based on TiN metamaterial from visible light to mid-infrared

We study and design an ultra-broadband absorber based on TiN metamaterial. The proposed structure consists of a rectangle pillar, two rectangle rings, an Al 2 O 3 substrate, and a TiN substrate. The average absorption in the range of 300–4962 nm is 97.02%. The physical mechanism is illustrated by electric-field and magnetic-field distributions, including the dielectric lossy property of TiN itself in shorter wavelengths, Fabry–Perot resonance, and local surface plasmon resonance in longer wavelengths. The result indicates that the energy absorption spectrum can be well matched with the standard solar spectrum under AM 1.5 over the full range of 300–5000 nm, and then we compare the solar absorption spectrum of different structures. In the end, the influence of different materials and geometrical parameters on absorption is investigated. The absorber can achieve ultra-broadband perfect absorption, and has a simple structure that is easy to manufacture. The result of this work can be applied in many potential fields, for example, thermal photovoltaic power generation, infrared imaging, solar cells, and other optoelectronic devices.