High efficient ultra-broadband nanoscale solar energy absorber based on stacked bilayer nano-arrays structure

Solar energy harvesting is widely used in heating and cooling system desalination of sea water, PV and solarthermal power generation, in which high efficient broadband solar energy absorber is a key technology and challenge. In this paper, an excellent nanoscale solar energy absorber based on stacked bilayer nano-arrays (SBNA) structure is proposed and investigated. By introducing 1D Ti grating in the first layer nano-array, the absorptivity in the long-wavelength range is enhanced and the absorption band is much broadened. Besides, combined the circular and elliptical nano-disks stacked with Ti - Al2O3 - Ti - Al2O3 in the second layer nanoarray, the average absorptivity in the whole work band can be improved, especially in short-wavelength range that dominates most solar energy. The result shows that the average absorptivity is up to 97.71% in the solar energy concentration range from 300 nm to 2500 nm. In the whole work band from 300 nm to 4000 nm, the average absorptivity is 94.10% and the absorption bandwidth (A > 90%) reaches 3080 nm. It's calculated that the solar spectral weighted absorption efficiency reaches to 98.35% in 300 nm-4000 nm, which is a rather high efficiency among the similar structure. Moreover, the solar energy absorber is polarization independent and is insensitive to large-angle incidence in 300 nm-2500 nm. The results provide a theoretical basis to design the absorption metamaterials in solar energy harvesting element. & COPY; 2023 xxxxxxxx. Hosting by Elsevier B.V. All rights reserved.