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2015
Conference Paper
Titel
Development of multicrystalline silicon for 20 % efficient n-Type solar cells
Abstract
Multicrystalline silicon suitable for high efficient n-type solar cells has been developed by directional solidification with seeded growth. The effect of varying initial grain sizes on mean grain size and dislocated area fraction over ingot height has been studied by applying different seeding compositions. Granular seed material resulted in the smallest initial grain size at the ingot bottom and the lowest dislocated area fraction at each ingot height. Lifetime analysis before and after a Boron diffusion step revealed that recombination in dislocated areas as well as grain boundaries can limit the mean lifetime in different heights in the same ingot. The efficiencies of solar cells with the TOPCon structure on these materials were predicted by an ELBA analysis. By use of a multicrystalline silicon plate as seed material a high quality material with a predicted cell efficiency of 20 % for processed isotextured wafers of the top ingot region could be realised. Solar cell efficiencies exceeding 21 % are expected if further material optimization by suitable seed selection and an adapted texturing process is applied.
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