Further absorption enhancement in ultra-thin solar cells structured with multiple-level grating

Light trapping methods could increase effective optical path length of light and hence the probability of its absorption inside the solar cell which is vital for thin film even ultra-thin film solar cells design. However, the patterned solar cells are always faced with the increase of recombination, especially the surface recombination. In other words, surface recombination plays a key role in high 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. Several main kinds of multiple-level grating are investigated in our work. This concept of multiple-level grating shows significant importance in effective nanostructure light trapping.