Regeneration of boron-oxygen related degradation in Cz-Si PERC-type solar cells at high temperatures

Abstract

Boron-oxygen related light induced degradation (BO-LID) may be eliminated by applying a regeneration process which converts the recombination active ‘degraded’ defects responsible for BO-LID into an inactive ‘regenerated’ state. As industrial mass production demands for fast, inline-capable processes and as the regeneration reaction accelerates with increasing temperature, it seems straightforward to increase treatment temperature. However, it is found that a reverse reaction destabilizes the ‘regenerated’ state at high temperatures and thus the ‘regenerated’ state is not necessarily the preferred defect state at high temperatures. Within this contribution it is investigated up to which temperature the regeneration process can be applied for boron-doped Cz-Si PERC solar cells. Experiments are accompanied and compared to theoretical predictions. In addition, it is found that the samples under investigation suffer from a second LID effect. Whether this can be attributed to LeTID, degradation of surface passivation quality or a different mechanism remains unclear.