Semiconductor-nanoantenna-assisted solar absorber for ultra-broadband light trapping.

Light trapping is an important performance of ultra-thin solar cells because it cannot only increase the optical absorption in the photoactive region but it also allows for the efficient absorption with very little materials. Semiconductor-nanoantenna has the ability to enhance light trapping and raise the transfer efficiency of solar energy. In this work, we present a solar absorber based on the gallium arsenide (GaAs) nanoantennas. Near-perfect light absorption (above 90%) is achieved in the wavelength which ranges from 468 to 2870 nm, showing an ultra-broadband and near-unity light trapping for the sun's radiation. A high short-circuit current density up to 61.947 mA/cm is obtained. Moreover, the solar absorber is with good structural stability and high temperature tolerance. These offer new perspectives for achieving ultra-compact efficient photovoltaic cells and thermal emitters.