Wang Hao, Wang Liping
Opt Express. 2013 Nov 4;21 Suppl 6:A1078-93. doi: 10.1364/OE.21.0A1078.
In this work, we numerically investigate the radiative properties of metamaterial nanostructures made of two-dimensional tungsten gratings on a thin dielectric spacer and an opaque tungsten film from UV to mid-infrared region as potential selective solar absorbers. The metamaterial absorber with single-sized tungsten patches exhibits high absorptance in the visible and near-infrared region due to several mechanisms such as surface plasmon polaritons, magnetic polaritons, and intrinsic bandgap absorption of tungsten. Geometric effects on the resonance wavelengths and the absorptance spectra are studied, and the physical mechanisms are elucidated in detail. The absorptance could be further enhanced in a broader spectral range with double-sized metamaterial absorbers. The total solar absorptance of the optimized metamaterial absorbers at normal incidence could be more than 88%, while the total emittance is less than 3% at 100°C, resulting in total photon-to-heat conversion efficiency of 86% without any optical concentration. Moreover, the metamaterial solar absorbers exhibit quasi-diffuse behaviors as well as polarization independence. The results here will facilitate the design of novel highly efficient solar absorbers to enhance the performance of various solar energy conversion systems.
在这项工作中，我们对由二维钨光栅、薄介电间隔层和不透明钨膜组成的超材料纳米结构在紫外到中红外区域的辐射特性进行了数值研究，该结构作为潜在的选择性太阳能吸收器。具有单一尺寸钨片的超材料吸收器由于表面等离激元极化激元、磁极化激元和钨的本征带隙吸收等多种机制，在可见光和近红外区域表现出高吸收率。研究了几何结构对共振波长和吸收光谱的影响，并详细阐明了物理机制。采用双尺寸超材料吸收器可在更宽的光谱范围内进一步提高吸收率。优化后的超材料吸收器在正入射时的总太阳能吸收率可超过88%，而在100°C时的总发射率小于3%，在无任何光学聚光的情况下，总光子到热的转换效率达到86%。此外，超材料太阳能吸收器表现出准漫射行为以及偏振无关性。这里的结果将有助于设计新型高效太阳能吸收器，以提高各种太阳能转换系统的性能。
