Slotted metallic nanospheres with both electric and magnetic resonances for solar thermal conversion

Due to its excellent optical characteristics, plasmonic nanoparticles have attracted great interest for the application in the direct absorption solar collectors (DASCs). The optical properties of nanospheres, nanorods, core/shell nanoparticles, and star-shape nanoparticles have been investigated. These nanostructures can induce localized surface plasmon resonance (LSPR) which is associated to electric resonance. However, at the occurrence of LSPR, besides the reinforced absorption, the scattering is also greatly enhanced, which can be detrimental for direct solar energy absorption. In this study, we proposed slotted metallic nanospheres for solar thermal conversion. Both electric and magnetic resonances can be excited in the slotted nanospheres, beneficial for solar energy absorption along the broad solar spectra. Compared to electric resonance, the excited magnetics resonances in the slotted nanosphere cause weaker scattering, which can better contribute to the absorption of solar energy. The study also showed that the optical proprieties can be effectively tuned by varying the particle size and number of slots. The proposed slotted nanospheres have good potential to be used in a DASC for solar thermal conversion and other photothermal applications.