In a research work supported by the Swiss Federal Office of Energy, the Swiss Federal Laboratories for Materials Testing and Research (Empa) has achieved 21.38% power conversion efficiency for flexible CIGS solar cells on polymer film, which the team terms as a new efficiency record.
This efficiency was independently measured at Fraunhofer Institute for Solar Energy Systems (ISE) of Germany.
For their research work, the scientists processed high efficiency flexible solar cells on a polymer film with the help of a low temperature co-evaporation method for the growth of the Cu((In,Ga)Se2 based thin film semiconductor. Empa Scientist Shiro Nishiwaki, explained the institute, optimized the composition of the layer and alkali dopants to improve performance further.
Resulting effects of combined heat and illumination exposure were studied by the researchers after processing solar cells and they found improved PV performance that 'remains stable after several months'.
The researchers see the application of these flexible CIGS solar cells for roofs and facades, greenhouses, transport vehicles, airships and portable electronics. Empa said it collaborates with Swiss CIGS module company Flisom for roll-to-roll manufacturing of lightweight flexible solar modules for such applications. Flisom is a spin-off of the Laboratory of Solid State Physics of the Swiss Federal Institute of Technology Zurich (ETH Zurich).
This 21.38% efficiency level is an improvement over the previous efficiency levels achieved by the scientists starting from 12.8% in 1999, increasing to 14.1% in 2005, 17.6% in 2010, 18.7% in 2011, 20.4% in 2013, and 20.8% in 2019 (see Empa Achieves 20.8% CIGS Flexible Solar Cell Efficiency).