On May 19th, 2011, researchers at the Swiss Federal Laboratories for Materials Testing and Research (EMPA, Switzerland) announced that they have reached a new world record of 18.7% efficiency with flexible copper indium gallium diselenide (CIGS) solar photovoltaic (PV) cells.

This efficiency has been verified by the Fraunhofer Institute for Solar Energy Systems (Freiburg, Germany), and is much higher than the previous record of 17.6% set by the same team in June 2010.

"The new record value for flexible CIGS solar cells of 18.7% nearly closes the "efficiency gap" to solar cells based on polycrystalline silicon (Si) wafers or CIGS thin film cells on glass," states team leader Ayodhya Tiwari of Empa's Laboratory for Thin Film and Photovoltaics.

"Flexible and lightweight CIGS solar cells with efficiencies comparable to the "best-in-class" will have excellent potential to bring about a paradigm shift and to enable low-cost solar electricity in the near future."

Flisom to commercialize technology

The EMPA team worked with scientists from Flisom AG (Dübendorf, Switzerland) on low-temperature growth of CIGS layers to create the flexible CIGS cells. Flisom has plans to scale and commercialize the CIGS technology.

EMPA states that these results indicate the potential for efficiencies above 16% with monolithically interconnected flexible CIGS modules.

Polymer films used instead of metal foil

EMPA states that its latest improvements in cell efficiency were made possible through a reduction in recombination losses by improving the structural properties of the CIGS layer and the low-temperature deposition process for growing the layers.

In situ doping with sodium during the final stage also contributed to the increased efficiency.

The institute notes in this process polymer films have shown superior performance to metal foils as a carrier substrate.

Potential cost advantages in manufacturing, balance of system

EMPA notes that the possibility of manufacturing CIGS cells on roll-to-roll processing equipment offers a path to lower manufacturing costs.

The institute also notes the advantages in transportation and installation of flexible and lightweight modules, which can reduce balance of system costs.

2011-05-20| Courtesy: EMPA | solarserver.com © Heindl Server GmbH

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