Light Trapping for Thin Silicon Solar Cells by Femtosecond Laser Texturing

Femtosecond laser texturing is used to create nano-to micron-scale surface roughness that strongly enhances light-trapping in thin crystalline silicon solar cells. Light trapping is crucial for thin solar cells where a single light-pass through the absorber is insufficient to capture the weakly absorbed red and near-infrared photons, especially with an indirect-gap semiconductor absorber layer such as crystalline Si which is less than 20 mu m thick [1-2]. We achieve enhancement of the optical absorption from light-trapping that approaches the Yablonovitch limit [3].