High Efficiency Hydrogenated Nanocrystalline Silicon Solar Cells Deposited at High Rates

We report recent progress on hydrogenated nanocrystalline silicon (nc-Si: H) solar cells prepared at different deposition rates. The nc-Si: H intrinsic layer was deposited, using a modified very high frequency (MVHF) glow discharge technique, on Ag/ZnO back reflectors (BRs). The nc-Si: H material quality, especially the evolution of the nanocrystallites, was optimized using hydrogen dilution profiling. First, an initial active-area efficiency of 10.2% was achieved in a nc-Si: H single-junction cell deposited at similar to 5 angstrom/s. Using the improved nc-Si: H cell, we obtained 14.5% initial and 13.5% stable active-area efficiencies in an a-Si: H/nc-Si: H/nc-Si: H triple-junction structure. Second, we achieved a stabilized total-area efficiency of 12.5% using the same triple-junction structure but with nc-Si: H deposited at similar to 10 angstrom/s; the efficiency was measured at the National Renewable Energy Laboratory (NREL). Third, we developed a recipe using a shorter deposition time and obtained initial 13.0% and stable 12.7% active-area efficiencies for the same triple-junction design.