Bert Thin Films launches copper paste for the metallization of solar cells on the back

US-based Bert Thin Films (BTF) has unveiled a new copper paste for back-side metallization of solar cells.

According to the manufacturer, the new paste can be screen printed and air baked, and can also be co-baked with commercial silver pastes for front metallization.

“The metallization process followed conventional industrial operations,” said Matthew Healy, the company’s Chief Sales Officer pv magazine. “A standard M10 wafer is initially printed using an automated screen printer with CuBert™ copper pastes on the back and then dried. The wafer is then turned over and printed with a standard silver paste on the front and dried. The wafer is then transported to a belt oven for a thirty second bake profile with a peak temperature of over 700 C. The cells are finally processed using a Laser Enhanced Contact Optimization (LECO) tool.”

The company tested the new metallization product on a TOPCon architecture using typical industrial screen printing and high-temperature firing ovens. The co-fire occurred mid-air at one of the facilities and also at an undisclosed independent location. Unspecified commercial silver pastes were used for the back metallization.

“In December we achieved 25% efficiency on sequential TOPCon fires, as well as successful 2,000 hours of moist heat data,” Healy said, without giving further details. “These results demonstrate that high-efficiency devices can be fabricated using silver-front pastes and BTF-copper back-side pastes.”

In April, BTF launched a copper metallization paste on the front. The CuBert copper-based paste can be integrated into existing production lines and formulated to work with the LEGO process.

Bert Thin Films, Inc., based in Kentucky, is focused on enabling copper-based solar cell manufacturing for a range of device architectures. It was awarded $1 million in funding by the U.S. Department of Energy in 2021.

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