Long Term Stability Analysis of Copper Front Side Metallization for Silicon Solar Cells

Kraft, Achim; Wolf, C.; Lorenz, Andreas; Bartsch, Jonas; Glatthaar, Markus; Glunz, Stefan W.

doi:10.1016/j.egypro.2014.08.012

Cited by 14 publications

(17 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the other hand, ambient cooling may allow any interstitial copper present in the wafer to out-diffuse to the surface where it cannot impact cell performance. The degradation results presented here appear to confirm such observations, and are also in agreement with previous studies on the degradation of copper-plated cells under thermal stress [14][15][16]. Although it is assumed here and in previous pFF studies after heat treatment that reduced pFF is due to copper penetration, there remains the possibility that ingress of nickel may also contribute to the observed pFF reductions.…”

Section: Methodssupporting

confidence: 93%

“…al. [15] examined the long-term impact of copper metallisation on solar cells through pseudo fill factor (pFF) measurements during thermal stress testing, based on the assumption that a decrease in pFF corresponds to a certain depth of copper diffusion in silicon. Despite demonstrating sufficient thermal stability, non-uniformity in the barrier layer raised concerns over long-term cell performance.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of copper penetration in selective-emitter silicon solar cells using laser ablation inductively-coupled plasma mass spectrometry

Colwell

Lennon

2015

2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)

View full text Add to dashboard Cite

This paper reports on an investigation into the use of laser ablation inductively-coupled plasma mass spectrometry (LA-ICPMS) in analyzing copper diffusion through nickel barrier layers in selective-emitter silicon solar cells. Cells plated with nickel and copper were heat-treated at 200 °C for up to 15 hours. Following quenching in ethylene glycol, significant degradation was observed in the plated cells, whereas no degradation was observed in the slow cooled cells. Impurity analysis with high spatial resolution was obtained with LA-ICPMS, showing higher copper content in copper-plated cells after heat treatment compared to cells without copper plating or heat treatment. The limitations of LA-ICPMS for quantitative analysis and the importance of minimizing surface contamination to improve technique sensitivity are also highlighted.

show abstract

Section: Methodssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Analysis of copper penetration in selective-emitter silicon solar cells using laser ablation inductively-coupled plasma mass spectrometry

Colwell

Lennon

2015

2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)

View full text Add to dashboard Cite

show abstract

“…Figure 5 shows the peel-force results. Adding just 25 % of the original nickel chloride concentration leads to a significant adhesion drop of around Figure 6 shows the peel-force results of the nickel-free solution (2) compared to the solution with the three electrolyte main compounds (1). Both solutions show the same clear adhesion drop.…”

Section: Contact Exposure Experiments Without Applied Voltagementioning

confidence: 98%

“…The thin silver capping avoids corrosion of the copper and creates suitable conditions for interconnecting the cells by soldering. Using this concept, the overall frontside silver consumption can be lowered down to \16 mg per cell [2]. A challenge with this metallization is the poor adhesion of the metal contacts after plating.…”

Section: Introductionmentioning

confidence: 99%

Origin of corrosion effects in solar cell contacts during electrochemical nickel deposition

et al. 2014

Self Cite

View full text Add to dashboard Cite

In the present study, the chemical interaction between screen-printed solar cell front-side contacts and electrolyte solutions is investigated in detail. Especially the Ni-plating process is known to lower the mechanical adhesion of solar cell contacts significantly. The mechanisms behind this adhesion loss were analyzed by performing contact exposure experiments with and without applied voltage in electrolyte solutions with subsequent characterization of the contact peel-force, complemented with X-ray-diffraction investigations of the material changes in the solid contact compounds. Reaction paths, behind the contact corrosion, as observed in SEM images, were identified: PbO and Ag2O out of the contact react with sulphates and chlorides in the electrolyte, forming lead sulphate and silver chloride. If a voltage is applied to the contacts an alternative more effective reaction path were identified. The voltage offers the possibility to reduce the dissolved lead and silver, and this shifts the equilibrium reactions strongly towards further dissolution. The activity of the reduction was found to depend on the reduction potential of the cations in the used electrolyte solution. The less noble the metal to be deposited on the solar cell contacts, the more difficult it is to achieve the deposition without adhesion loss of the screen-printed solar cell contact

show abstract

“…Further evidence to support the assumed stability of Cu‐plated modules in the field has been provided by studies that have evaluated the effectiveness of various Ni barrier layers on maintaining the pseudo fill factor ( pFF ) of heat‐treated and cooled Cu‐plated Si solar cells at close to their initial values . The rationale for this analysis is that, if Cu penetrates through the barrier, then the performance of a solar cell will be most likely impacted first by junction recombination due to Cu's likely precipitation at the junction as discussed in Section 2.1.1.…”

Section: Challenges For Copper‐plated Silicon Solar Cellsmentioning

confidence: 99%

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

Lennon

Colwell

Rodbell

2018

Progress in Photovoltaics

View full text Add to dashboard Cite

Copper‐plated interconnects were widely adopted for volume manufacture of integrated circuits after more than a decade of intensive research to demonstrate that use of Cu would not impact device reliability. However, although Cu‐plated metallisation promises significantly reduced costs for Si photovoltaics, its adoption in manufacturing has not gained the same traction. This review identifies some key challenges facing the introduction of Cu‐plated metallisation for Si photovoltaics. These include the following: (1) increased carrier recombination due to the use of Cu for metal contact formation; (2) reduced module reliability due to adhesion or contact integrity failures; and (3) limited availability of cost‐effective processes and equipment for metal plating. For integrated circuits, Cu's low electrical resistance and high resistance to electromigration provided an impetus for the large investment in process development that was required to realise Cu‐plated interconnects. However, the technical advantages of using Cu for Si solar cell contacts are not as compelling, as solar cells can tolerate larger feature sizes thus reducing the criticality of the contact metal's conductivity and electromigration properties. Additionally, for Si photovoltaics, low cost is paramount, and new challenges arise from the need for modules to absorb light and operate in the field for 25+ years in diverse outdoor climates. However, with the scale of Si photovoltaic manufacturing expected to increase dramatically in the next decade, the use of large quantities of silver for cell metallisation will provide an incentive to address reliability concerns regarding the use of Cu for Si photovoltaic metallisation.

show abstract

Long Term Stability Analysis of Copper Front Side Metallization for Silicon Solar Cells

Cited by 14 publications

References 2 publications

Analysis of copper penetration in selective-emitter silicon solar cells using laser ablation inductively-coupled plasma mass spectrometry

Analysis of copper penetration in selective-emitter silicon solar cells using laser ablation inductively-coupled plasma mass spectrometry

Origin of corrosion effects in solar cell contacts during electrochemical nickel deposition

Challenges facing copper‐plated metallisation for silicon photovoltaics: Insights from integrated circuit technology development

Contact Info

Product

Resources

About