How Solder Flux Can Cause Significant Degradation in Heterojunction
Cells
- Haoran Wang,
- Chandany Sen,
- Jiexi Fu,
- Muhammad Umair Khan,
- Yutong Wu,
- Hao Song,
- Ruirui Lv,
- Gavin Conibeer,
- Bram Hoex
Haoran Wang
University of New South Wales School of Photovoltaic and Renewable Energy Engineering
Author ProfileJiexi Fu
University of New South Wales School of Photovoltaic and Renewable Energy Engineering
Author ProfileMuhammad Umair Khan
University of New South Wales School of Photovoltaic and Renewable Energy Engineering
Author ProfileGavin Conibeer
University of New South Wales School of Photovoltaic and Renewable Energy Engineering
Author ProfileBram Hoex
University of New South Wales School of Photovoltaic and Renewable Energy Engineering
Author ProfileAbstract
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Silicon heterojunction technology (HJT) and tunnel oxide passivated
contacts (TOPCon) solar cell technologies are expected to dominate the
photovoltaic market in the coming years. However, there are still some
concerns about the long-term stability of these technologies. This work
examines the effects of two widely used commercial soldering fluxes
(Flux A and Flux B) on the stability of commercial silicon HJT and
TOPCon solar cells. The soldering flux was applied to the solar cells,
and the solar cells were annealed at 85 oC under low
relative humidity. TOPCon solar cells were found to be stable; however,
significant degradation was observed in the HJT solar cells after only
50 hrs. The efficiency of the HJT cells decreased by ~
61% rel with Flux A and ~ 55%
rel with Flux B, respectively. We attribute part of the
observed degradation to holes present in the HJT cell metalisation after
printing, which allow the soldering flux to easily penetrate the contact
and subsequently react with the paste constituents. In addition, we find
that the indium tin oxide (ITO) layer is very sensitive to soldering
flux, showing major cracks and significant peeling after 50 hrs of
annealing. Consequently, this work shows that some soldering flux can
react with the ITO layer, without requiring the presence of water. This
suggests that certain types of soldering flux can harm HJT solar cells
even after encapsulation without the need for moisture ingress.
Therefore, paying more attention to the choice of soldering flux is
essential, especially when working with HJT cells. It is strongly
recommended that users perform comprehensive component analysis testing
on soldering fluxes before their official use rather than solely relying
on datasheets provided by suppliers.Submitted to Progress in Photovoltaics Submission Checks Completed
Assigned to Editor
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09 Jul 2024Review(s) Completed, Editorial Evaluation Pending
31 Jul 2024Reviewer(s) Assigned