Effect of electrical bias on metastability in hydrogenated nanocrystalline silicon solar cells

The effect of electrical bias on metastability in hydrogenated nanocrystalline silicon (nc-Si:H) solar cells is studied. We find that forward bias current injection in the dark does not cause any degradation in nc-Si:H solar cells, while light soaking under reverse bias enhances the light-induced degradation in the cell performance. These phenomena are contrary to those found in hydrogenated amorphous silicon solar cells. We argue that the forward injected carriers mainly transport through the nanocrystallites where carrier recombination does not create metastable defects. The increased degradation under reverse bias is explained in terms of the heterogeneity of the material structure.