High efficiency triple-junction solar cells with hydrogenated nanocrystalline silicon bottom cell

We report on an a-Si:H/a-SiGe:H/nc-Si:H triple-junction nip solar cell deposited on Ag/ZnO back reflector coated stainless steel substrate. The initial and stable active-area efficiencies of 14.6% and 12.6%, respectively, have been achieved by optimizing the nc-Si:H bottom cell using a hydrogen dilution profiling technique for controlling the evolution of nanocrystalline structure, improving the back reflector for light trapping, and optimizing the device design.