Ultra-broadband Wide-Angle Metallo-Dielectric Metamaterial Absorber for Solar Energy Harvesting

We present analytical and numerical investigations revealing a new recipe of ultra-broadband metamaterial absorber, comprising a periodic 1D grating of a multilayered, alternating metal-dielectric, tapered structure. We report over 99% absorption using molybdenum (metal) - germanium (dielectric) layers at normal incidence in the visible and near-infrared regime of the solar radiation spectrum. The broadband absorption is attributed to multiple slow-wave modes getting absorbed at different layers. Additionally, our simulation model shows angle insensitivity up to 60 degrees. Absorbance spectra, obtained from effective medium theory, agree well with our simulation results. Potential applications can be solar energy harvesting and stealth technologies.