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Solar Cells and Mini-Modules Based on 40 Μμm-Thick Epitaxial Si Foils: Towards Conductive Bonding onto Low-Cost Si Powder Sintered Conductive Carriers from the Recycling of Silicon Waste
H. Sivaramakrishnan Radhakrishnan, K. Van Nieuwenhuysen, J. Govaerts, V. Depauw, T. Bearda, M. Debucquoy, R. Roozeman, J. Heikkinen, M. Schumann, R. Buchwald, H.J. Möller, A. Ciftja, G. Stokkan, E.-J. Øvrelid, A. Stonkus, P. Dubravskij, J. Ulbikas, I. Gordon, J. Szlufcik, J. Poortmans, A. Ulyashin
Thin Film Solar Cells and Modules
Subtopic: Silicon-based Thin Film Solar Cells and Modules
Event: 32nd European Photovoltaic Solar Energy Conference and Exhibition
Session: 3DV.1.15
1268 - 1271
ISBN: 3-936338-41-8
Paper DOI: 10.4229/EUPVSEC20162016-3DV.1.15
0,00 EUR
Document(s): paper


Epitaxial silicon foils (<50 um) lifted-off using the porous silicon-based layer transfer process are used to fabricate heterojunction (HJ) solar cells. Mini-modules with efficiencies above 15% have been fabricated using standard lamination and encapsulation techniques, which have been applied to freestanding epi-Si based HJ solar cells. Analysis of this module highlights the need for bonding these cells onto supporting substrates before module fabrication. We suggest using very low-cost conductive Si carriers as the supporting substrates. Sintering of low-cost Si powder-based ingots, assisted by in-situ doping, has been done by hot pressing or casting of ingots using different types of Si powders and was followed by multi-wire sawing to fabricate thin (~170 μm) supporting highly conductive substrates. The Si material used for these substrates can, in principle, be obtained from Si waste streams, e.g. broken wafers or end-of-line cells in production lines, Si kerf or end-of-life PV modules, making this even more attractive proposition. One important aspect is the development of conductive bonding of epitaxial foils onto low-cost sintered silicon substrates.We evaluated different types of conductive bonding agents. Good mechanical stability was achieved for the bonding processes. These efforts represent the first step towards the wafer-equivalent approach of high efficiency solar cells on thin Si (<50 μm) conductively bonded to low-cost Si substrates. This approach is considered as a promising route for the low-cost Si based PV and a solution module integration of thin Si. This work is done in framework of H2020 EU project CABRISS.