Bimetallic metasurface broadband perfect absorber for high-efficiency thermal photovoltaics

We theoretically propose and demonstrate that broadband polarization-insensitive perfect visible light absorption can be realized in a periodic bimetallic nanotriangle structure with a thick gold plate. The average absorption is 95.79% from 400 nm to 800 nm. The multiple localized surface plasmon resonances of the bimetallic nanostructure are the major contributions to this broadband perfect absorption in the visible region. Meanwhile, the physical mechanism of the broadband perfect absorption of the bimetallic nanostructure can be well interpreted by impedance matching theory. Moreover, the average photo-thermal conversion efficiency is up to 93% over a wide temperature range.