Correlation of the open-circuit voltage enhancement of heterogeneous silicon solar cells and the Staebler-Wronski effect

We recently reported on a significant light-induced enhancement in the open-circuit voltage (V_oc) of heterogeneous silicon solar cells whose intrinsic layer consists of a mixture of amorphous and microcrystalline silicon phases. In this study, we examine the effect of applying a reverse bias to the cell during light soaking and discover that the variation in V_oc is greatly suppressed. In addition, we find that subjecting the heterogeneous cells to a forward bias in the dark causes an enhancement in V_oc, similar to the open-circuit light-soaking effect. Based on these two experiments, we conclude that the cause of the V_oc enhancement is the same as that of the Staebler-Wronski effect.