Spatially resolved analysis of light induced degradation of multicrystalline PERC solar cells

Light induced degradation at elevated temperatures in mc-Si PERC solar cells can be responsible for major efficiency losses. In this work, a spatially resolved analysis of the degradation behavior of a standard mc-Si PERC solar cell is performed based on carrier lifetime-calibrated photoluminescence (PL) images. An effective defect concentration is calculated from lifetime data at a fixed injection which allows for defect analysis taking into account any other defects. The time-dependent defect evolution is fitted to obtain the spatially resolved maximum effective defect concentration and the degradation time constant. No differences in the behavior between grains and dislocation clusters could be observed. Lower effective defect concentrations have been found around grain boundaries which could be an effect of denuded zones. In the case of our sample, slight local process and material parameter variations, namely the local firing temperature, have a much stronger impact than the crystal structure.