Researchers at Fraunhofer ISE have developed a process that makes it possible to replace silver with copper in solar cells. The spin-off company PV2+ is to market the new technology.
A team of researchers led by Dr. Markus Glatthaar, an expert in metallization and patterning, has developed an electroplating process that replaces silver with copper in the promising heterojunction technology. Copper is many times cheaper and more readily available.
To prevent the entire electrically conductive surface of the solar cell from being electroplated with copper, the areas that are not to be coated must be masked beforehand. These areas receive an electrically insulating coating that prevents galvanic deposition. Thus, the copper layer grows only in the non-insulating coated areas.
The researchers have made a second significant advance here: To mask the silicon wafer in the electrolyte bath, the industry previously used expensive polymer-based coatings or films. Proper disposal of the polymers is costly and causes a lot of waste. Glatthaar and his team succeeded in substituting the polymers with aluminum. Like copper, aluminum can be fully recycled. The double switch – from silver to copper and from polymer to aluminum – also brings a double advantage: the production of solar cells becomes more sustainable and at the same time significantly cheaper.