Solar cells reach 18% efficiency

IMEC has unveiled a large-area solar system with a conversion efficiency of 18.4%.

Compared with the standard i-PERC cell process, this cell features a shallow emitter and advanced front metallisation using copper plating. 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 metallisation stack is added which is applied to local openings in the anti-reflective coating.

Dr Joachim John, team manager at IMEC, said:

“Using copper instead of silver adds to the sustainability of solar cell production. IMEC was able to do this because it has 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 without dedicated finetuning makes this result “particularly encouraging”.

Dr Jef Poortmans, IMEC's Photovoltaics program director, said:

“These cells and the new metallisation stack involved are a further step in IMEC's target to develop ever more cost-effective, efficient crystalline Si solar cells - eventually targeting cells that are 40 µm thick with efficiencies above 20%.”