New limits for light-trapping with multi-resonant absorption

We propose a new paradigm for light trapping in solar cells. It is based on multi-resonant absorption (MRA) with a two-dimensional periodical pattern. We develop a simple theoretical model and we derive the upper limit of optical absorption in a slab of semiconductor. This MRA limit exceeds the conventional Lambertian limit (4n
²
) by a factor of π for any absorber thickness: the maximum optical path enhancement factor is F=4πn
²
. We describe the main results and discuss the strong thickness reduction achievable with multi-resonant lighttrapping strategy.