Optimized metamaterial solar absorber with ultra-wideband, polarization-independent and large incident angle-insensitive

Metamaterial absorbers have received a lot of attention because of their wide range of applications in collecting solar energy, photovoltaics (PV), thermal emitters, and sensors. In this paper, by virtue of the finite-difference time-domain (FDTD), a simple ultra-wideband metamaterial perfect absorber is proposed which is made from a Ti substrate, a Si3N4 spacer layer and a two-dimensional Si3N4-Ti periodic pattern array. The optimized results indicate that under the condition of vertical incidence, the wideband absorption spectrum range of the absorber is 500nm to 3700nm, and the average absorption is 97.03%. On bases of the multi-resonance coupling of the surface plasmon resonance (SPR), the cavity resonance (CR) and the magnetic resonance (MR), an ultra-broadband perfect absorption effect is achieved. The absorber structure has a relatively wide absorption bandwidth and polarization-independent characteristics, which is very much insensitive to the large angle of incidence of TE and TM polarization waves. All in all, our proposed absorber is a potential candidate for solar-related energy applications.