Effect of EVA Encapsulation on Antireflection Properties of Mie Nanoscatterers for c-Si Solar Cells

Dielectric nanoparticle arrays have been proposed as antireflection coatings and light-trapping schemes for thin-film c-Si solar cells. However, practical aspects about the integration of these nanostructures with solar modules have yet to be investigated. In this paper, we study the effect of ethylene vinyl acetate (EVA) encapsulation on the optical properties of dielectric nanoparticles placed on top of c-Si substrates. We experimentally show that Si nanoparticle Mie coatings encapsulated in an EVA layer yield ultralow reflectivity over the entire 300-1000-nm spectral range. The AM1.5-weighted average reflectivity of the Mie coating is as low as 1.5%, which is comparable with that of a standard alkaline texture used for c-Si solar cells. TiO₂ nanoparticle Mie coatings also yield similar results. Mie coatings are thus valid substitutes of standard textures for ultrathin devices. We also study the case of plasmonic nanoparticle coatings for c-Si solar cells. We find that they are not suited for c-Si cells when EVA encapsulation is used.