Light-induced degradation in compensated n-type Czochralski silicon solar cells

This study focuses on the evolution under illumination of the electrical performances of solar cells made with n-type boron-phosphorus compensated Czochralski silicon. First, we show via carrier lifetime measurements that this material is sensitive to light-induced degradation (LID) effects due to the formation of BO(i2) complexes. Solar cells were then processed with this compensated material. The cells performances were found to be dependent on the position of the wafer along the ingot height. This dependence is due to carrier lifetime variations along the ingot height and is not directly linked with the differences in concentration between boron and phosphorus. LID experiments were then performed on the same cells. Unlike what was suggested from previous studies, we highlighted a weak decrease of the cell performances under illumination, consistent with the electrical characterizations at the wafer level. These degradations have been quantified and linked with the chemical composition of the material. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim