High-performance low-cost silver-coated copper paste for silicon heterojunction solar cells

Conductive silver pastes dominate electrode manufacturing in silicon heterojunction (SHJ) solar cells but suffer from high and volatile material costs. While silver-coated copper particles (Cu@Ag MPs) offer a promising low-cost alternative, conventional synthesis methods struggle to achieve uniform coatings, leading to poor oxidation stability and conductivity. Herein, we introduce a novel chloride-ion-assisted chemical reduction method to synthesize high-quality Cu@Ag MPs. The introduced Cl⁻ ions act as an electrostatic dispersant, effectively suppressing copper agglomeration and enabling the formation of a uniform and dense silver shell. The optimized Cu@Ag MPs (30 wt% Ag) exhibit excellent oxidation resistance below 300 °C and a low resistivity of 1.90 mΩ. When formulated into a low-temperature curing paste for SHJ solar cells, the composite ink achieves a volume resistivity of 8.22 × 10 –6 Ω·cm after curing at 210 °C. Remarkably, the paste demonstrates outstanding environmental stability, with only 1% resistivity degradation after 30 days of ambient exposure. This work presents a viable and cost-effective solution for photovoltaic metallization, reducing silver consumption by 70% while maintaining performance parity with commercial pastes, thereby paving the way for more sustainable solar cell manufacturing.