Multi-Resonant Full-Solar-Spectrum Perfect Metamaterial Absorber.

Currently, perfect absorption properties of metamaterials have attracted widespread interest in the area of solar energy. Ultra-broadband absorption, incidence angle insensitivity, and polarization independence are key performance indicators in the design of the absorbers. In this work, we proposed a metamaterial absorber based on the absorption mechanism with multiple resonances, including propagation surface plasmon resonance (PSPR), localized surface plasmon resonance (LSPR), electric dipole resonance (EDR), and magnetic dipole resonance (MDR). The absorber, consisting of composite nanocylinders and a microcavity, can perform solar energy full-spectrum absorption. The proposed absorber obtained high absorption (>95%) from 272 nm to 2742 nm at normal incidence. The weighted absorption rate of the absorber at air mass 1.5 direct in the wavelength range of 280 nm to 3000 nm exceeds 98.5%. The ultra-broadband perfect absorption can be ascribed to the interaction of those resonances. The photothermal conversion efficiency of the absorber reaches 85.3% at 375 K. By analyzing the influence of the structural parameters on the absorption efficiency, the absorber exhibits excellent fault tolerance. In addition, the designed absorber is insensitive to polarization and variation in ambient refractive index and has an absorption rate of more than 80% at the incident angle of 50°. Our proposed absorber has great application potential in solar energy collection, photothermal conversion, and other related areas.