Optical confinement in thin silicon films: a comprehensive ray optical theory

This paper describes a ray-optics theory to analyze optical confinement in silicon solar cells using random or periodically rough surfaces. This theory considers multireflections within the cell. It also takes into account polarization and interference effects to include antireflection coatings and local nonnormal incidence of light. The results are given in terms of parameters such as reflectance, transmittance, and absorbance for global AM1.5 illumination. A variety of thin-film structures, suitable for light trapping, are compared in terms of the maximum achievable current densities. The paper emphasizes optical concepts that are necessary to design thin-film solar cells using nonplanar interfaces