Swiss scientists achieve 22.2% efficiency for flexible CIGS solar cell

Researchers from Switzerland's Federal Laboratories for Materials Science and Technology (EMPA) claim to have achieved a world record efficiency of 22.2% for a flexible copper, indium, gallium and selenium (CIGS) solar cell on polyimide plastic film.

Germany's Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) has confirmed the results. As of September 2021, the cell had an efficiency of 21.4%.

The device was fabricated through a low-temperature co-evaporation method for the growth of the light-absorbing CIGS semiconductor thin film. EMPA scientist Shiro Nishiwaki optimized the composition of the layer and alkaline dopants to achieve improved performance.

“The current increase in efficiency is due to the alloying of the light-absorbing semiconductor layer to improve its electronic properties,” the research group said. 

The solar cell has been developed by the research team over the past 23 years. Their “record streak” started in 1999 with an efficiency of 12.8%, then went on to 14.1% (2005), 17.6% (2010), 18.7% (2011) and 20.4%( 2013) and finally reached 20.8% in 2019 and 21.4% last yer.

“The flexible and lightweight solar modules resulting from this technology are particularly suitable for applications on roofs and facades of buildings, greenhouses, transport vehicles, airships and portable electronic devices,” the head of the laboratory for thin films and photovoltaics, Ayodhya Tiwari, told pv magazine in a recent interview on the future of CIGS technology. “EMPA collaborates with the Swiss company Flisom for the manufacture of flexible and lightweight solar modules by roll-to-roll processes for such applications.”

Japan's Solar Frontier has achieved the highest efficiency for a CIGS solar cell to date, at 23.35%. German thin-film module maker Avancis has reached the highest efficiency for a solar panel, at 19.64%.