All screen-printed industrial n-type Czochralski silicon solar cells with aluminium rear emitter and selective front surface field

The influence of the base dopand on the cell performance in a cell type with selective front phosphorus diffusion and an alloyed aluminum rear doping is investigated in this work. First this was done by using two dimensional device simulations to vary the doping species (n- or p-type) and the concentration over a broad range. For n-type base material we found that for a given front side system (diffusion and passivation) the fill factor tends to increase while the short circuit current decreases with increasing base doping concentration. The ideal base doping is therefore a function of the quality of the front side diffusion and passivation. In comparison to the n-type cells the dependence of the p-type cell results on the base doping concentration is much weaker. Based on the simulations a base doping concentration of 8 □cm was chosen to process n-type solar cells, which were then compared with identically processed p-type cells. For our front and rear screen-printed large-area n- as well as for our p-type cells we have achieved efficiencies up to 17.6 %.