Chinese researchers have developed a new type of paste made from silver and nickel (Ag-Ni) for use in the production of solar cells. This paste is designed for the rear side of tunnel oxide passivated contact (TOPCon) solar cells, a type known for its high efficiency. The new paste could potentially reduce the cost of the rear metallization process by around 11 percent, which is a significant saving in solar cell manufacturing. The research, titled « Hybrid silver-nickel screen-printed contacts for the SiOx/n+-Poly-Si layers of TOPCon solar cells », was published in Progress in Photovoltaics: Research and Applications. The team involved scientists from Yangzhou University, Jiaxing University, and Changzhou University in China. Their goal was to find a more cost-effective way to produce high-efficiency solar cells by replacing some of the silver in the paste with nickel, a cheaper material. Silver has become a major cost factor in solar cell production, especially with the increasing use of high-efficiency technologies like TOPCon and heterojunction (HJT) cells. These technologies rely heavily on silver-based pastes for their electrical connections. The researchers found that using a combination of silver and nickel could help reduce costs without significantly affecting the cell's performance. However, factors like contact resistance, conductivity, and long-term reliability remain important to address. In their experiments, the team tested different nickel concentrations in the paste, ranging from 6 percent to 60 percent. They found that lower concentrations of nickel had minimal impact on cell efficiency, but higher concentrations led to a sharp drop in performance due to increased electrical resistance and recombination losses. The paste containing 10 percent nickel was found to offer the best balance between cost and performance. After further optimization, including adjustments to the silver powder and glass frit composition, the team achieved an average conversion efficiency of 26.67 percent in a production test. This is slightly lower than the 26.77 percent achieved with traditional silver paste, but the cost savings are significant. The study highlights the potential of Ag-Ni pastes to support the sustainable growth of the solar industry by reducing reliance on silver.