Large Area Solar Cells With 18.4% Conversion Efficiency, Featuring Cu-plated Contacts

The results were obtained on large-area cells (125 cm²), proving the industrial viability of the process.

The shallow emitter results in an enhanced blue response, and thus in a higher conversion efficiency than with a standard emitter. For the front contacts, a novel metallization stack is added which is applied to local openings in the antireflective coating.

Dr. Joachim John, team manager at IMEC: “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. ”

Dr. Jef Poortmans, IMEC’s Photovoltaics Program Director, states: “These cells and the new metallization 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%."