Broadband Metamaterial Solar Absorbers Based on the Earth First-rate Temperature-Insensitivity Metals for High Temperature Energy Harvesting

Abstract

Artificially engineered solar absorbers, known as metamaterial solar absorbers (MSA), are yielding new opportunities for designing new photons management systems. Furthermore, the noble metals are indispensable in creating MSA owing to their plasmonic resonance in a desired spectral region. Nevertheless, in high temperature applications, the noble metals suffer from low melting points that make their uses largely impractical. In this work, the solution of using four of the Earth first-rate temperature-insensitivity metals in a proposed MSA is investigated. The proposed MSA structure is composed of high melting point metals (HMPM), deposited on a magnesium fluoride (MgF\(_2\)) dielectric spacer and a tungsten continuous plate. Meanwhile, owing to the dependence of MSA properties on structural parameters rather than band structure or chemistry, a geometrical optimization of the proposed absorbers is reported. Furthermore, the proposed MSA performance is investigated by computing the absorption spectrums. Results show relatively long bandwidths in the visible and near-infrared regimes. Besides, an underlying mechanism of the absorption enhancement with the corresponding electromagnetic field distributions is elucidated in detail. The calculated results indicate that the proposed MSA present wide bandwidths owing to the excitation of resonance modes of surface plasmons, dipolar interactions and cavity modes. Equally important, absorption measurements under wide polarization angles show polarization-insensitive high absorption at higher wavelengths, which is among the most important factors for an ideal solar absorber. The conclusion of this investigation is undoubtedly important, specifically that the proposed HMPM-based MSA would be the best choice for energy harvesting in high temperature applications.