Study of the bulk lifetime and material saturation current density of different p-type monocrystalline silicon materials

With efficiencies of industrial type PERC solar cells exceeding 22% and reduced electrical and optical losses in these high efficiency cells, it becomes more and more important for manufacturers to rely on high quality silicon wafers. In this contribution, we present data of the bulk excess carrier lifetime τbulk and a doping density independent material quality parameter at maximum power point, the material saturation current density j0,mat, of different p-type monocrystalline silicon materials. These values are obtained by measuring the effective carrier lifetime of neighbouring wafers of different thickness and thus eliminating the surface recombination contribution. We show that j0,mat is an adequate parameter to evaluate the bulk quality of a given material. To further validate these findings, we compare the results to PERC cell efficiencies obtained with the same material.