Perfect spectrally selective solar absorber with dielectric filled fishnet tungsten grating for solar energy harvesting

A perfect spectrally selective solar absorber based on dielectric filled fishnet-shape tungsten grating has been proposed and numerically investigated. The designed structure achieves a total solar absorption efficiency higher than 94% and a total emittance less than 5% at 100 degrees C, resulting in a total photothermal conversion efficiency of 93.4% irradiated by one sun. In addition, the proposed selective solar absorber exhibits nearly perfect absorption in visible and near-infrared regions (400-1200 nm), and the underlying physical mechanisms for the excellent performance including the impedance matching with surrounding medium, surface plasmon resonances, and cavity resonances are elucidated in detail. Furthermore, effects of the proposed solar absorber geometric parameters on the absorption properties of it are also analyzed. Moreover, the solar absorber exhibits angular independence up to 60 degrees and polarization insensitivity. The proposed spectrally selective solar absorber promises potentially valuable applications for thermophotovoltaic conversion, thermal emitters, solar energy harvesting, and so on.