Symmetry-breaking nanostructures for enhanced light-trapping in thin film solar cells

We introduce a manufacturable method to break the symmetry in inverted nanopyramids on c-Si. This method broadly enhances light trapping and would increase the efficiency from 25 to 26.4% for thick c-Si cells. We further use the nanopyramids as a template to deposit plasmonic metal structures and demonstrate enhanced light absorption in organic solar cells. The enhancement exceeds 100% in some cases by concentrating the plasmonic bands tuned to the polymer absorption. The result agrees well with our measured surface plasmon polariton band structures. We expect our approach to be broadly applicable to thin-film solar cells.