Title:	Copper Plating Process for Bifacial Heterojunction Solar Cells
Author(s):	A. Lachowicz, J. Geissbühler, A. Faes, J. Champliaud, F. Debrot, E. Kobayashi, J. Horzel, C. Ballif, M. Despeisse
Keywords:	High Efficiency, Copper Plating, Silicon Heterojunction
Topic:	Silicon Photovoltaics
Subtopic:	Heterojunction Solar Cells
Event:	33rd European Photovoltaic Solar Energy Conference and Exhibition
Session:	2AV.3.22
Pages:	753 - 756
ISBN:	3-936338-47-7
Paper DOI:	10.4229/EUPVSEC20172017-2AV.3.22
Price:	0,00 EUR
Document(s):	paper

Abstract/Summary:

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We describe a process sequence for bifacial heterojunction (HJT) solar cells with simultaneous plating on both sides from a developed copper electrolyte. The process comprises the deposition of a PVD seed layer, patterning by advanced inkjet printing of a hotmelt-ink mask and copper electroplating, followed by optional deposition of a capping layer such as immersion silver to facilitate interconnection in modules. Subsequently, the mask and the seed layer are chemically removed. Our copper electrolyte yields layers with very low internal stress when plating at high plating rates above 3 μm/min. The combination of a sputtered seed layer and electroplated copper with low internal stress allows for good adhesion even for very thick plated layers as required for instance for shingled solar cell interconnection or 6” IBC solar cells. An aperture conversion efficiency above 24% has been independently confirmed for a large area solar cell with a four busbar front grid utilizing an industrial heterojunction precursor.