Tungsten nanopore-based near-ideal spectral selective solar absorber for a wide temperature range

An efficient and simple spectral selective solar absorber is vital for solar-thermal systems that operate under a wide temperature range (673-1573 K). However, few absorbers are competent for this wide temperature range due to their suboptimal spectral selectivity under specific conditions or complex structures that are difficult to be fabricated. Here, we proposed a near-ideal spectral selective solar absorber consisting of simple regular hexag-onal tungsten nanopores filled with silicon dioxide. A strong solar absorptivity up to 0.9632 and a reduced total emissivity down to 0.0961 were realized due to its good spectral selectivity. Meanwhile, the near-ideal spectral selective solar absorber obtains high photothermal efficiencies of 95.25 % at 673 K, 95.84 % at 873 K, and 89.38 % at 1573 K when the concentration ratios are 100, 1000, and 2000 suns, respectively. Subsequently, mechanism analysis implies that the excellent performance of the near-ideal absorber results from the electromagnetic field enhanced by the cavity resonances, localized surface plasmon resonances, and surface plasmon polaritons. Further, the impedance matching also plays an important role in achieving the excellent performance. In addition, the near-ideal absorber also shows insensitivity to incident angle and polarization angle with both TE and TM waves. All the above positive properties presented by the near-ideal absorber indicate that it is a good option for solar energy capture in the wide temperature range of 673-1573 K.