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

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 similar to 1 mu m dimensions can significantly increase absorption in a thin layer under light concentration. A 50 nm thick GaSb active layer in the described configuration absorbs similar to 66% of the incident solar photons above the band gap for a concentration equivalent to a numerical aperture NA=1/root 2. This absorption represents a similar to 76% or 26% increase over the same structure but with the grating removed or substituted by an ideal antireflection coating, respectively. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3512898]