Modeling and realization of photonic structures for silicon-based tandem solar cells

Different photonic light trapping structures realized by a combination of interference- and nanoimprint-lithography as well as based on self-organization processes are presented. Their potential as rear side light trapping structures for silicon based tandem solar cells is evaluated based on the comparison of EQE measurements and optical modeling. The photonic structure used in the current world record III-V silicon tandem solar cell is a metallic crossed grating with 1μm period. This structure is shown in detail and acts as benchmark for the comparison of the concepts. Finally, the requirements for a successful implementation of photonic structures in highest efficiency solar cells are shown.