Silver-lean screen-printing can reduce silver use in TOPCon solar cells by 40%

An international research team has developed a metallization technique for TOPCon solar cells that can reportedly reduce silver usage in the devices’ rear side by 85%. The scientists replaced the commonly used Ag fingers with intermittent Ag dashes for contact formation and Ag-free fingers and busbars for electrical conduction.

May 9, 2025 Emiliano Bellini

The rear side of a TOPCon solar cell fabricated with the silver-lean metallisation design

Image: Image: UNSW, Solar Energy Materials and Solar Cells, CC BY 4.0

Researchers from the University of New South Wales (UNSW) in Australia and China’s metallization paste specialist Changzhou Fusion New Materials claim to have developed a silver-lean screen-printing metallization technology that can significantly reduce silver (Ag) consumption in TOPCon solar cells without impacting device efficiency and performance.

With the proposed technique, the scientists replaced the commonly used Ag fingers with intermittent Ag dashes for contact formation and Ag-free fingers and busbars for electrical conduction.

“This dual-layer configuration addresses the main challenges associated with using silver-lean paste materials in silicon solar cells by avoiding the formation of direct metal/Si interfaces with those alternative pastes,” the group explained.

The novel two-step printing process is implemented first by printing conventional silver pastes as seed layers and then by printing the silver-lean fingers on top. With this configuration, the silver-lean fingers are intended for electrical conduction only, with the metal/Si interfaces being no longer essential for this purpose.

“This approach not only broadens the choices of silver-lean pastes that can be potentially used in TOPCon solar cells but also significantly eases the requirements on future paste developments,” the academics stressed.

A schematic diagram of such a dual-layer design, illustrating both continuous and dashed seed layer configurations
*Image: Image: UNSW, Solar Energy Materials and Solar Cells, CC BY 4.0*

The new metallization technique was tested in a 25%-efficient TOPCon solar cell and was found to result in an 85 % reduction in rear-side silver usage, with total silver consumption reaching just 7 mg/W, and a 40% reduction compared to industrial TOPCon cells with standard Ag metallization.

The cell also showed a “marginal” efficiency difference of 0.1–0.2 % compared to reference cells based on standard Ag metallization.

The scientists believe that through the optimization of the so-called laser-enhanced contact optimization (LECO) and the commercially available pastes for the dash design, the efficiency gap can be reduced or even eliminated.

“As another appealing option, the use of Ag dashes in conjunction with aluminum (Ac) fingers was found to be challenging due to the undesirable interaction between Ag and Al pastes during the co-firing process,” they also explained. “Further developments and optimizations in existing industrial standard Ag and Al pastes will be critically needed to overcome such a challenge.”

Their findings are available in the paper “Silver-lean screen-printing metallisation for industrial TOPCon solar cells: Enabling an 80% reduction in silver consumption,” which was recently published in Solar Energy Materials and Solar Cells.

Previous research on TOPCon by UNSW showed the vulnerability of TOPCon solar cells to contact corrosion and three types of TOPCon solar module failures that were never detected in PERC panels. Furthermore, UNSW scientists investigated sodium-induced degradation of TOPCon solar cells under damp-heat exposure and degradation mechanisms of industrial TOPCon solar modules encapsulated with ethylene vinyl acetate (EVA) under accelerated damp-heat conditions.

More recently, another UNSW team has found that the Special Injected Metallization (JSIM) technique developed by Chinese manufacturer Jolywood can considerably increase TOPCon solar cell efficiency. The scientists described precisely how laser-assisted firing enhances cell performance, reportedly filling critical gaps in industrial TOPCon cell optimization.

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