Fabrication of high-contrast gratings for a parallel spectrum splitting dispersive element in a concentrated photovoltaic system

High-contrast gratings are designed and fabricated and their application in a parallel spectrum splitting dispersive element is proposed that is found to have the potential to improve the solar conversion efficiency of a concentrated photovoltaic system. This proposed system will also lower solar cell cost in the concentrated photovoltaic systems by replacing the expensive tandem solar cells with cost-effective single-junction solar cells. The structures and parameters of the high-contrast gratings for the dispersive element are numerically optimized, and a large-area fabrication is experimentally demonstrated using nanoimprint lithography and dry etching. Both the quality of the material and the performance of the fabricated device are experimentally characterized and discussed.