Multiple-level grating used for nanostructured thin film solar cells

Surface recombination plays a key role in hign efficiency nanostructured thin film solar cells. How to reduce the recombination in a nanostructured cell or further increase absorption without increase of surface recombination is meaningful in solar cell design. We further increases light absorption without increase of surface recombination, and the extra light absorption contribute to the device efficiency. This concept of multiple-level grating shows significant importance in effective nanostructure light trapping.