Hybrid plasmonic metamaterials: towards enhanced ultra broadband and wide-angle solar absorption for energy harvesting

In this paper, we have investigated a hybrid metamaterial seven-layer solar absorber. The absorber has remarkable characteristics, including ultra-broadband perfect absorption capability, near-perfect absorption at wide angles, and insensitivity to polarization. The structure exhibits an average absorption of 98.05% across the spectral range of 300 to 5000 nm. Furthermore, the absorption bandwidth exceeding 90% spans more than 4950 nm. We have analyzed the absorptivity of the structure considering various optical mechanisms, including propagating surface plasmon resonance (SPR), local surface plasmon resonance (LSPR), guided-mode resonance (GMR), and magnetic resonance (MR). This solar absorber comprises two layers of SiO₂-Fe and a layer of semi-oval TiN arrays. Despite specific geometric tolerances, it effectively maintains ultra-broad absorption performance from the visible to the mid-infrared (MIR) range. The structure demonstrates insensitivity to a wide range of polarization angles, up to approximately 65 degrees. This makes it a promising candidate for applications such as solar energy harvesting, thermal emitters, solar cells, and related technologies.