Solar cells molded into thin and versatile films could expand renewable energy generating possibilities and reduce manufacturing costs. One group of experts in Switzerland has been attempting to improve the technology’s efficiency to that of rigid solar cells, and they’ve now established a new milestone of 21.4%.
The study was conducted at Swiss Federal Laboratories for Materials Science and Technology (Empa), where researchers have spent years developing CIGS (copper, indium, gallium, and selenium) flexible solar cells. The Empa group has been at the forefront of thin-film solar cell development for almost two decades. These are among just a few thin-film solar cells under mainstream development with adaptable applications in mind.
CIGS flexible solar cells are not quite there yet, since the greatest non-flexible solar cells, constructed with crystalline silicon, can transform light into energy with up to 26.7 percent efficiency. In 1999, the Empa team set a new record of 12.8 percent efficiency, followed by 14.1% in 2005, 17.6% in 2010, 18.7% in 2011, 20.4% in 2013, and 20.8% in 2019.
As we can see, the team has come a long way, but they are getting closer to the finish line with yet new breakthrough. The researchers employ a process termed low-temperature co-evaporation to build a semiconducting film on the top of a thin polymer layer to make their cells. The team was able to improve the photovoltaic performance of the film by adjusting the composition and alkali dopants employed to give it electrical characteristics.
Scientists from Fraunhofer Institute for Solar Energy Systems in Germany independently validated the solar cell’s efficiency of 21.38% over several months. While this effort sets a new record for Empa scientists and CIGS cells, other forms of flexible cells have achieved even greater efficiencies by merging with other photoactive substances like perovskite. We observed one of such tandem cells, which could also be placed onto the flexible film, achieve a 24.16% efficiency last year.
According to scientists working on commercial applications, flexible solar cells might be used on building and roofs facades, mobile devices, aircraft, and ground vehicles. In addition to being lightweight and sticking to curved or complicated surfaces, these cells allow for cheaper roll-to-roll manufacturing, potentially lowering the cost of renewable energy. This week, Empa researchers presented their newest findings at the 38th European Photovoltaic Solar Energy Conference and Exhibition.