Size and microstructure effect of silica nanosphere assemblies on antireflective capability in film solar cell applications

We address the problem of broadband optical scattering by microassemblies of submicron spherical silica particles functioning as an antireflective (AR) coating applied to the outer layer of a typical solar cell. Using full-wave electromagnetic modeling based on the finite element method, we perform numerical studies of the near-field spatial distribution near such microassemblies with different internal microstructures. The assemblies can be either fully ordered or possess a disordered nanotexture formed by random packing of multiple silica nanospheres (NSs). The main objective of our study is to evaluate the light transmission efficiency through the surface layer of a representative solar cell depending on the structural design of the NS-based AR coating. We show that, depending on the optical properties of the substrate, minimization of unwanted optical reflection in the spectral range of solar radiation is achieved at different angles of incidence using AR coatings consisting of subwavelength NSs arranged in a certain number of ordered (densely packed) or disordered (sparsely packed) consecutive layers.