Figure 3. Solar superabsorption in single nanostructures and an array of nanostructures.

(a) The maximal solar absorption of single 0D nanostructures (a-Si is included as the absorbing materials) as a function of the volume of a-Si materials. The calculation result includes an estimated 20% error as indicated by the shaded areas. The inset is a schematic illustration for the nanostructure, whose irregular shape is intentionally chosen to illustrate that the structure may have any arbitrary shapes. (b) Solar superabsorption limit of an array of 0D nanostructures. The minimum volume of a-Si materials necessary to absorb >90% of the solar radiation above the band gap is plotted as a function of the period of the array. The inset is a schematic illustration for the nanostructure array.