Metamaterial-plasmonic ultra-thin absorbers for thin film solar cells

We show that a planar structure, consisting of an ultrathin semiconducting layer topped with a solid nanoscopically perforated metallic film and then a dielectric interference film, can highly absorb (superabsorb) electromagnetic radiation in the entire visible range, and thus can become a platform for high-efficiency solar cells. Our quantitative simulations confirm that the superabsorption bandwidth is maximized at the checkerboard pattern of the perforations. These simulation results show that the energy conversion efficiency of a single-junction amorphous silicon solar cell based on the optimized structure can exceed 12%.