Broadband wide-angle polarization-insensitive metasurface solar absorber.

In this paper, a new ultra-thin and broadband wide-angle polarization-insensitive metasurface solar absorber is designed and optimized. The proposed metasurface absorber topology is optimized by using a genetic algorithm to enhance the bandwidth and decrease the unit cell area. The proposed unit cell is designed with fourfolded symmetric subunit cells rotated in the clockwise direction to achieve a polarization-independent response. The unit cell with 320×320  nm area and 50 nm thickness has a broadband (≥90%) absorption response in the visible frequency region of the solar spectrum and infrared from 350 THz to 700 THz for normal incident angles and higher than 70% for incident angles up to 40° at both polarizations.