Light trapping designs for thin silicon solar cells based on photonic crystal and metallic diffractive grating structures

We present novel light trapping designs applied to thin (5 micron) silicon solar cells. The design structures incorporate diffractive gratings to increase the optical path length of light within the solar cells. We incorporate a combination of dielectric and metallic materials to create the gratings. We form a one dimensional photonic crystal stack with the dielectric materials to which we then add the metallic layers. The combination of the two materials enhances the reflective properties of the gratings and thus increasing their effectiveness in light trapping. We use the particle swarm optimization and scattering matrix methods to realize the design structures.