Broadband and wide-angle solar absorber for the visible and near-infrared frequencies

A polarization-insensitive broadband and wide-angle solar absorber in the visible to near-infrared regions is proposed and studied. The proposed absorber is in the form of an iron square ring array separated from an iron reflector by a dielectric spacer and a phase change material (Ge2Sb2Te5) layer. About 98% averaged absorption in the spectral range of 380-2000 nm is realized. The electromagnetic filed intensity distribution at several selected absorption peaks is studied to provide physical understanding behind the broadband absorption effect. Besides, the high absorption performance remains stable within a large viewing angle and the designed absorber shows certain dimensional tolerance, which decreases the fabrication complexity and cost and should be attractive for practical applications. Moreover, the potential applications of the proposed scheme on the solar energy harvesting are also illustrated in the last. It is believed that the proposed absorbers should find potential applications in solar energy capturing and conversion, thermo-photovoltaic devices and thermal emitters.