Silica-sol-based spin-coating barrier layer against phosphorous diffusion for crystalline silicon solar cells

Area of Science:

• Materials Science
• Semiconductor Physics
• Photovoltaics

Background:

• Phosphorus diffusion is critical for creating n(+) emitters in silicon solar cells.
• Uncontrolled phosphorus diffusion can lead to efficiency losses.
• Existing barrier methods can be complex or costly.

Purpose of the Study:

• To develop and evaluate a cost-effective silica-sol barrier for phosphorus diffusion.
• To investigate the impact of this barrier on silicon solar cell performance.
• To optimize the application of the silica-sol layer.

Main Methods:

• Fabrication of phosphorus barrier layers using spin-coating of silica-sol and tetramethylammonium hydroxide.
• Optimization of coating thickness via spin-coating speed (2,000–8,000 rpm).
• Fabrication of crystalline silicon (CZ-Si) p-type solar cells with and without the rear silica-sol layer.
• Characterization using sheet resistance measurements, Secondary Ion Mass Spectrometry (SIMS), and Scanning Electron Microscopy (SEM).

Main Results:

• The spin-coated silica-sol film effectively prevented phosphorus out-diffusion during high-temperature annealing.
• Solar cells fabricated with the silica-sol barrier showed a ~2% improvement in conversion efficiency.
• Sheet resistance, SIMS, and SEM analyses confirmed the barrier's effectiveness and material properties.

Conclusions:

• Silica-sol is a promising, low-cost, and easily applicable spin-coating barrier material for phosphorus diffusion masking.
• This technique offers a viable solution for enhancing silicon solar cell efficiency.
• The method is suitable for various applications requiring controlled phosphorus diffusion.