Researchers in China found that fine tuning the lead(II) oxide (PbO) and silicon dioxide (SiO₂) molar ratio in silver paste glass frits affects silver-silicon contact resistance in crystalline silicon solar cells. They found that an intermediate ratio optimizes interfacial structure, lowering contact resistance and improving efficiency by 1 percentage point.
A research team led by China’s Sichuan University has investigated methods to tune the content of lead(II) oxide (PbO) and silicon dioxide (SiO₂) within silver paste, with the aim of reducing contact resistance at the silver-silicon (Ag–Si) interface in crystalline silicon solar cells and thereby improving overall device performance.
“We systematically investigated the effect of the PbO/SiO₂ molar ratio—the most fundamental and critical compositional parameter in glass frits—on the Ag–Si contact performance,” corresponding author Jingquan Zhang told pv magazine. “We also clarified the intrinsic ‘composition–structure–property’ relationship, providing a rational design guideline for high-performance silver-paste glass frits.”
The scientists explained that glass frits are key components in silver paste, as they enable sintering and interfacial reactions during processing. They lower the processing temperature, etch the silicon nitride (SiNx) anti-reflection layer, and enhance the dispersion and wettability of silver particles. Most importantly, they promote the formation of an interfacial layer that reduces contact resistance between silver electrodes and silicon. In this process, SiO₂ forms the backbone of the glass network structure, while PbO serves as a network modifier that tunes viscosity, glass transition temperature, and chemical reactivity.
