Light beam induced current of light-induced degradation in high-performance multicrystalline Al-BSF cells

Multicrystalline silicon solar cells are plagued by different types of light-induced degradation (LID), including Sponge-LID. Sponge-LID decreases the Al-BSF cell efficiency by up to 10 %rel. and is only partially recoverable at 200°C. This contribution shows that Sponge-LID occurs at and near most grain boundaries, but only in the centre of the affected cell. Furthermore, Sponge-LID is not the only type of LID in the silicon bulk. High-resolution Light Beam Induced Current mapping reveals local internal quantum efficiency losses of up to 8 %rel. at dislocation clusters and small angle grain boundaries, which recover (nearly) fully at 200°C. Nevertheless, this dislocation-related LID appears to reduce the Al-BSF efficiency by less than 1 %rel.