Study of changes in PL spectrum from defects in PERC solar cells with respect to LeTID

Illumination at elevated temperature may cause an efficiency loss of more than 10 %rel. in mc-PERC cells. In this study, we have looked for changes in the photoluminescence spectrum of mc-PERC cells before and after light and elevated temperature induced degradation and, subsequently, after a following regeneration has commenced. We found that combined light and temperature treatment gave different responses depending on if the trap level state in the band gap was deep or shallow.