Ultra-wideband solar absorber based on double-polygonal metamaterial structures

In this work, a novel solar absorber with wide angle tolerance and insensitivity to polarization is proposed. The upper layer of the absorber comprises two polygonal structures, which can achieve an absorption rate of 94.2% across a broad wavelength range of 2218 nm (584 nm - 2802 nm). The performance of the absorber is simulated and verified using the finite difference time domain (FDTD) method combined with impedance matching theory. Through examining the electromagnetic field distribution at absorption peaks, the physical mechanism is elucidated. Moreover, incorporating refractory metals and nonmetallic materials in its design enhances the stability of the absorber, making it suitable for various extreme environments. This indicates its potential applications in solar energy storage and solar thermal photovoltaic systems.