Surface plasmon enhanced light-trapping in polycrystalline silicon thin-film solar

The paper reports a development and implementation of light trapping based on light scattering from plasmonic metal nanoparticles. The nanoparticles were formed on the surface of planar polycrystalline Si thin-film solar cells by annealing of a precursor Ag film. The light absorption by the cells and resulting photocurrent enhancement is maximised by optimising the design of the nanoparticle light-trapping scheme, which includes the nanoparticle size and location, the local dielectric environment, and an application of a supplementary back surface reflector. A large photocurrent enhancement is achieved due to high scattering and coupling efficiencies of the incident light from Ag nanoparticles into the thin-film cells. For the optimum design comprising a 'Si-film/nanoparticles/magnesium fluoride/diffuse white paint' structure short-circuit current enhancement of 44% is demonstrated for the cell fabricated by e-beam evaporation on 3 mm thick planar glass superstrate. The enhancement is further increased up to 50% when the developed light-trapping scheme is applied to the cell fabricated by PECVD on 1 mm thick planar glass superstrate.