Effect of impurities on performance of hydrogenated nanocrystalline silicon solar cells

We found that for O content as high as ∼2×1019 at./cm3, hydrogenated nanocrystalline silicon (nc-Si:H) solar cell having 10.6% efficiency is attainable, when a small amount of B ∼1–3×1016 at./cm3 is incorporated. Micro-doping compensation is critical for high efficiency nc-Si:H cells absent very low residual impurities. Quantum efficiency (QE) loss in the long wavelength region is observed when O is present, which loss can be eliminated by micro-doping with a compensating element such as B. However, when the B content exceeds a certain compensation level, a QE loss in short wavelength region is observed.

► We have achieved 10.6% efficiency in a nc-Si:H single-junction solar cell.
► QE loss has a good correlation with impurity levels of O and B.
► Micro-doping compensation of O and B is critical for high efficiency solar cells.