Study on a Novel Selective Solar Absorber With Surface Ultrathin Metal Film

In this paper, simple selective solar absorbers with three layers are investigated, and their selective absorptivity spectra are quite appropriate for high performance solar absorbers. The simple solar absorber contains top ultrathin tungsten (W) layer, middle silica layers and W substrate. The thickness of silica can determine the location of absorptivity peak while the thickness of top W layer affects the intensity of absorptivity. Considering the total conversion efficiency, optimized thicknesses in solar absorbers are determined by genetic algorithm. This optimized thin film solar absorber keeps high absorptivities when incident direction varies from 0 degree to 60 degree in both TE and TM polarizations. Experiments validate the effectivity of thin film solar absorbers, and the deviation from simulations comes from increscent refractive index and surface non-uniform.