Tungsten Nanowire Metamaterials as Selective Solar Thermal Absorbers by Excitation of Magnetic Polaritons

The present study focuses on nanowire based metamaterials with excitation of magnetic polariton (MP) as selective solar absorbers. Finite-difference time-domain simulation is employed for numerically designing a broadband solar absorber made of lossy tungsten nanowires which exhibit spectral selectivity due to the excitation of MP. An inductor-capacitor circuit model of the nanowire array is developed in order to predict the resonance wavelengths of the MP harmonic modes. The effects of geometric parameters such as nanowire diameter, height, and array period are investigated and understood on tuning the magnetic polariton resonance and the resulting optical and radiative properties. In addition, the independence of incidence angles is demonstrated, which illustrates the potential applicability of the nanowire-based metamaterial as a high-efficiency wide-angle selective solar absorber. The results will facilitate the design of novel low-cost and high-efficiency materials for enhancing solar thermal energy harvesting and conversion.