Imec reports large-area silicon solar cells with high efficiency

Imec attributed the efficiencies above 19% to a combination of improved texturization and optimized firing conditions.

Rick Nelson, Chief Editor -- EDN, September 7, 2010

At the 25th European Photovoltaic Solar Energy Conference (Valencia, Spain) this week, Imec is presenting several large-area silicon solar cells with a conversion efficiency above 19%. In particular, Imec said it realized two types of cells with Ag-screen-printed contacts and plated Cu-contacts. Efficiencies of cells with screen-printed contacts reached 19.1%, while cells with Cu-plated contacts achieved efficiencies of 19.4%. Imec attributed the efficiencies to several factors, including a combination of improved texturization and optimized firing conditions. The results were achieved on large-area cells (148 cm²) with 170-µm thickness, proving the industrial viability of the process.

Imec's silicon solar cells feature rear-side passivation, laser ablation, and local aluminum back-side field and screen-printed contacts or Cu-plated contacts on advanced emitter schemes. "The fact that such efficiencies can be obtained by metallization schemes based on screen-printed Ag contacts enables compatibility with present industrial metallization practice in the solar cell industry," said Dr Joachim John, team manager industrial solar cells at Imec. "The Cu-based front-side metallization is a step towards higher sustainability and lower cost," he added.

"High efficiency, low cost, and sustainability are the main drivers in Imec's research on crystalline silicon solar cells, eventually targeting cells that are only 40 µm thick with efficiencies above 20," said Dr. Jef Poortmans, director of the Imec energy/solar program. He added, "We expect further improvements towards efficiencies of up to 20% for large-area silicon solar cells."

The results were achieved within Imec's silicon solar-cell industrial affiliation program (IIAP), a multi-partner R&D program that explores and develops advanced process technologies aiming at sharp reduction in silicon use, while increasing cell efficiency and hence further lowering the cost per watt peak.