Microstructure and recombination activity of grain boundaries from front and rear side during a LID-cycle of mc-PERC solar cells

Under illumination multi-crystalline PERC solar cells may suffer from a severe efficiency loss up to 20 %
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induced by carrier injection which is known as mc-LID (or LeTID). Lateral investigations show that grain boundaries as well as the rear side are of special interest. Target preparation and element analysis at locations with high rear recombination unveil Cu-containing particles at industrially produced mc-Si PERC solar cells. They accumulate at grain boundaries and at the rear surface where the passivation stack is damaged. The correlation of these Cu particles and mc-LID is examined.