Investigation on Low Firing Copper for Front Electrode of Si-Based Solar Cell Applications

Area of Science:

• Materials Science
• Renewable Energy Engineering
• Nanotechnology

Background:

• Silicon solar cells are a cornerstone of alternative energy.
• Developing cost-effective and efficient front electrodes is crucial for solar cell performance.
• Traditional methods often involve high temperatures and complex processes.

Purpose of the Study:

• To create a low-cost, low-temperature process for ohmic contacts in silicon solar cells.
• To utilize a novel Cu-core Ag-shell (CucoreAgshell) paste for front electrode fabrication.
• To enhance conductivity and prevent oxidation in solar cell electrodes.

Main Methods:

• Preparation of Cu-core Ag-shell powders.
• Formulation of high solid content paste.
• Screen printing on laser-opened H-pattern silicon substrates.
• Low-temperature sintering (firing) process.
• Microstructural analysis using TEM, EDS, and SEM.
• Electrical characterization via four-point probe and transmission line model.

Main Results:

• Achieved high silver coverage (>95%) with nanoparticles melting around 200 °C.
• The silver shell effectively prevented copper oxidation and enhanced conductivity.
• The lowest specific contact resistivity achieved was 0.005 Ωcm².
• Lowest sheet resistance measured was 0.0138 Ω/.
• Lowest front electrode resistivity was 2.65 × 10⁻⁵ Ωcm at 550 °C with 94 wt% solid content paste.

Conclusions:

• The developed CucoreAgshell paste and low-temperature sintering process successfully form efficient ohmic contacts.
• This method offers a cost-effective and low-temperature alternative for silicon solar cell front electrode fabrication.
• The enhanced conductivity and stability of the CucoreAgshell electrodes show significant promise for improving solar cell efficiency.