Ultrathin nanostructured solar selective absorber based on a two-dimensional hemispherical shell array

摘要

A distinctive ultrathin nanostructured solar selective absorber is demonstrated experimentally. It consists of a self-assembled, two-dimensional, closely packed hexagonally distributed tungsten hemispherical shell array coated with an ultrathin germanium film (20 nm in thickness) and a silicon dioxide antireflective film. Due to the combined light trapping effects of unconventional interferences within the germanium film and the excited surface plasmon polaritons at the tungsten-germanium interface, as well as the antireflection effect of the silicon dioxide layer, the solar absorption of this absorber (0.93) is about as high as that of commercial black paint (0.94) and much higher than that of its planar counterpart (0.83). With greatly suppressed emission/absorption in the long wavelength range, its heat accumulation is superior, enabling a much higher temperature (218 degrees C under 7-sun illumination) than its planar counterpart and the black paint absorber (203 degrees C and 181 degrees C under 7-sun illumination, respectively). Published by AIP Publishing.