IMEC (Interuniversity Microelectronics Center) has presented a large-area solar cell with 18.4% conversion efficiency at the ongoing European Photovoltaic Solar Energy Conference (Hamburg, Germany). A world leader in its own right, IMEC is an independent research center working on nanoelectronics and nanotechnology. It is headquartered in Leuven, Belgium, and has offices in Belgium, the Netherlands, Taiwan, US, China and Japan.

IMEC’s new solar cell incorporates a shallow emitter and uses copper plating for advanced metalization, compared to the standard i-PERC cell process. When the results were obtained on large-area cells (125cm2), the industrial viability of the process was verified.

According to Dr. Jef Poortmans, IMEC’s Photovoltaics Program Director, “These cells and the new metalization stack involved are a further successful step in IMEC’s target to develop ever more cost-effective, efficient crystalline Si solar cells - eventually targeting cells that are only 40µm thick with efficiencies above 20%.”

The higher conversion efficiency is obtained when the shallow emitter originates an enhanced blue response.

A novel metalization stack is added for the front contacts and this is applied to local openings in the anti-reflective coating. Dr. Joachim John, team manager at IMEC, explains it better, “Using copper instead of silver adds to the sustainability of solar cell production. IMEC was able to do this because it has extensive experience with copper plating on silicon. A similar efficiency result was obtained with screen printed contacts, but the long-term sustainability and low-cost potential of Cu-based contacting solutions and the fact that this was a first result obtained without dedicated fine-tuning makes this result particularly encouraging.”

This has been referenced from the recent IMEC press release.