Tungsten-based highly selective solar absorber using simple nanodisk array.

In this paper, we report the design, fabrication, and characterization of a tungsten-based metamaterial selective solar absorber (SSA) combining a metal-insulator-metal (MIM) structure and simple nanodisk array. The as-fabricated absorber absorbs strongly and selectively in the wavelength range of 0.5-1.75 μm with a characterized absorptance of more than 90%, which drops abruptly to less than 12.6% beyond 2.5 μm. In addition, this broadband and highly selective absorber is polarization-insensitive under incidence of normal plane waves. Moreover, the solar selectivity remains invariable up to 40°, which is beneficial for solar thermal applications. These properties are verified theoretically and experimentally in the present work. Further analysis on energy dissipation reveals the underlying physics and optical performances.