Dielectric gratings for wide-angle, broadband absorption by thin film photovoltaic cells

Abstract

Optical management is essential to increase absorption in thin photovoltaic cells. In this article, full electromagnetic simulations show that a back mirror and a one-dimensional front SiC sawtooth grating of ∼1 μm dimensions can significantly increase absorption in a thin layer under light concentration. A 50 nm thick GaSb active layer in the described configuration absorbs ∼66% of the incident solar photons above the band gap for a concentration equivalent to a numerical aperture NA=1/2. This absorption represents a ∼76% or 26% increase over the same structure but with the grating removed or substituted by an ideal antireflection coating, respectively. © 2010 American Institute of Physics.