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Title:
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Advanced light management for thin film silicon solar cells on foil
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Author(s):
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Published by:
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Publication date:
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ECN
Solar Energy
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22-9-2014
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ECN report number:
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Document type:
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ECN-M--14-051
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Conference Paper
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Number of pages:
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Full text:
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3
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Download PDF
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Abstract:
We present different new concepts to improve the light trapping in thin film silicon solar cells on steel foil. One of these concepts is to incorporate a textured back reflector, where the light scattering texture is made by Nano-Imprint Lithography (NIL). In this concept, we imprint a texture in a UV-hardening lacquer that has been applied on the steel foil. This texture then is covered by a silver layer, serving as a reflector and a back contact. Any arbitrary texture can be imprinted, and we have shown in the past that by this method we can obtain short circuit current density (Jsc) of more than 24 mA/cm2 for cells with a nanocrystalline silicon (nc-Si) absorber layer of only 1 micron. Here we present results showing that the concept can also be applied to fabricate thin film silicon solar cells on paper. Another approach is to replace this silver layer by a white back reflector (WBR). Since, in contrast to the utilization of a WBR in superstrate cells, in substrate-type n-i-p cells the WBR has to undergo all the different steps of the cell processing, there are strict requirements to the material of the WBR, in terms of degasing and temperature stability. We have identified suitable materials and applied these in amorphous silicon (a-Si) solar cells. The Jsc values of these cells were equal to those of cells with a NIL back reflector. Finally, we present a-Si/nc-Si tandem cells on foil in which we combine the NIL back reflector concept with an incorporated intermediate reflector (IR) based on n-type doped SiOx.
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