Broadband solar absorbers with excellent thermal radiation efficiency based on W-Al2O3 stack of cubes

A laminated cubic solar absorber (LCSA) with double metal-dielectric layers is proposed. It plays an extremely crucial character in the utilization of solar energy. In particular, it is necessary to realize the efficient absorption and heat conversion of solar energy. Through numerical analysis and calculation, it is concluded that the absorption efficiency of LCSA is greater than 90% from 420 nm to 2112 nm. Moreover, the weighted average absorption of Air Mass 1.5 (AM1.5) in the solar radiation range (280 nm-2500 nm) is greater than 96.32%. To explore the mechanism of this absorber, we analyzed the electromagnetic field distribution of the four peaks, and concluded that the reason for achieving the wide-band absorption is that the depth of the double-layer metal dielectric cube produces surface plasmas with different wavelengths. The incident angle insensitivity and polarization independence of LCSA are realized. The simulation results indicate that the thermal radiation efficiency is more than 90% at 2000 K. Based on the above advantages and the high temperature resistance of tungsten (W) and aluminum oxide (Al2O3), the proposed LCSA can be widely used in photothermal conversion and thermal emitters.