A new success has been achieved in the field of flexible solar cells: a team of Swiss scientists has produced solar cells that have a record efficiency of 21.4%. The research was conducted at the Swiss Federal Laboratories for Materials Science and Technology (Empa), where scientists over the years have developed flexible solar cells known as CIGS, a technology based on copper indium gallium diselenide (Cu(In,Ga)Se2), a composite semiconductor material that allows the production of flexible and lightweight solar cells on polymer film. To make these new cells, scientists used a technique called low-temperature co-evaporation, which deposits a very thin layer of semiconductor materials on a thin polymer film. By modifying the composition of the film and the alkaline dopants used to endow it with electrical properties, the team was able to increase its photovoltaic performance.
Celle solari flessibili CIGS: Crediti: Empa
Flexible solar cells represent a great promise for the future of renewable energy sources because not only could they open up new opportunities in the production of renewable energy, but also they could reduce production costs. The current problem is that the efficiency of such solutions is not sufficiently high. By comparison, conventional crystalline silicon cells can convert light into electricity with an efficiency of up to 26.7%. The Empa team has travelled a long road made up of important milestones: in 1999 an efficiency of 12.8% was achieved, 14.1% in 2005, 17.6% in 2010, 18.7% in 2011, 20.4% in 2013 and then 20.8% in 2019. This latest record brings this technology even closer to marketability.