Spectrum splitting photovoltaics: Light trapping filtered concentrator for ultrahigh photovoltaic efficiency

We investigate a spectrum splitting approach where light is trapped in a textured dielectric slab and coupled into underlying solar cells of different bandgaps through filters. We describe a specific design featuring an SiO_2 textured slab coated with angle restricting incoupling elements and four underlying dual junction subcells, based on light trapping and efficiency considerations. We then design a full set of four omnidirectional filters based on aperiodic dielectric multilayer films to split the light entering each subcell into spectral bands tuned to the cell bandgaps. Based on the calculated filter performance, we estimate a receiver efficiency of 45% with this initial design.