Optical modeling and optimization of flattened light-scattering substrate for thin-film silicon solar cells

The Flattened Light-Scattering Substrate (FLiSS) is a two-dimensional grating-based back reflector. Embedded in thin film silicon solar cells, it increases spectral response in the infrared region and delivers high-end open circuit voltage and fill factor, due to the roughness-free surface. An accurate three-dimensional optical modeling based on finite element method was carried out for implementation in efficient thin-film silicon solar cells. Three types of FLiSS shapes, different materials, and wide period/height ranges were simulated. Optimal FLiSS design results in a photo-current density of 27.4 mA/cm² for a 1 μm thick flat nip μc-Si:H single junction solar cell.