Influencing factors in solar cell contact resistance testing

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Influencing factors in solar cell contact resistance testing

Posted Date: 2024-01-16

In solar cell electrode optimization,Contact resistanceis an important factor to consider.Contact resistance is a measure ofMetal to semiconductor ohmic contact qualityThe key parameters can be calculated by studying the contact resistance.Reflects problems existing in processes such as diffusion, electrode fabrication and sintering.Meineng"TLM Contact Resistance Tester"you can use the contact resistivity test and line resistance test functions to test the performance of solar cells.Contact resistance,Sheet resistance,contact resistivityand grid linesLine resistanceetc. for accurate detection, and the measured data can be clearly and objectively presented in the TLM mapping software to help customers optimize these key battery parameters.

During the contact resistance measurement process, you need to pay attention to the following factors:

  • Sample width;
  • marginal shunt;
  • Current flow through undetected grid lines;
  • Uneven contact resistance;
  • Uneven sheet resistance

Next, I will introduce to you aboutSample widthandedge shuntimpact on the results.

Sample width

Samples with different widths have a greater impact on the measured contact resistivity values. The typical relationship between contact resistivity and sample width is shown in the figure below. When the sample width is from 5mm to 25mm, the measured contact resistivity and transfer length also increase accordingly.

The figure below shows the simulated TLM diagram (i.e. RT vs. contact spacing) for two sample widths (5mm and 30mm) and the ideal state. Ideally, with the same input material properties, if we scale the 5mm results by a factor of 1/6, we should get the same TLM plot. However, as shown in the figure, the contact resistance and transfer length obtained from the 30 mm sample are much greater than those obtained from the 5 mm sample.

edge shunt

It was introduced earlier that different sample widths will affect the contact resistivity. Through multiple measurements of different samples with different sample widths, it was also found that in many results, for small sample widths (5mm), the measured contact resistivity was very large, as shown in the figure below.

One possibility for this result is that laser cutting induces a shunt effect at the edge of the sample and creates additional shunt paths. The shunt path causes an increase in the measured contact resistance, an effect that becomes more pronounced when the sample width becomes smaller.

The graph above shows the contact resistance versus sample width for structures with and without edge shunting. We observe that edge shunting results in higher contact resistance measurements at all sample widths, with this effect being more pronounced at smaller widths.

For further analysis, a 10mm width gate line was tested, and the results showed that edge shunting changed the voltage distribution of the gate line. The voltage change at the end of the gate line is much larger than normal, indicating that more current is flowing from the end of the gate line.

Meineng TLM contact resistance tester

Meineng TLM contact resistance testercapable of measuring solar cells quickly, flexibly and accuratelyContact resistance and line resistance.Reflects problems existing in processes such as diffusion, electrode production, and sintering.

  • Contact resistivity test range: 0.1~120mΩ*cm^2;
  • Line resistance test range: 0.2~40Ω/cm
  • Contact resistivity measurement accuracy: 5% or 0.5mΩ*cm^2
  • Line resistance measurement accuracy: 5% or 0.1Ω/cm

Static test repeatability ≤1%, dynamic test repeatability ≤3%

Meineng TLM contact resistance measurement demonstration video

Meineng PhotovoltaicCommitted to researching test conditions, processes and algorithms to improve testing accuracy and efficiency to meet different testing needs.Meineng TLM contact resistance testercan accurately measure the contact resistance of solar cells to evaluate problems in diffusion, electrode production, sintering and other processes, and help customers accelerate the performance of solar cells!

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