Empa Has Smashed The Record For Efficiency In Flexible Solar Cells

Scientists at Empa confirmed that they have crushed the record for efficiency when it comes to flexible solar cells. Their new record is an efficiency of 21.4 percent for a flexible CIGS solar cell on a polymer film. This type of solar cell has particular usage applications, including designing solar panels for use on the roof of structures, mobile devices, and vehicles.

Independent measurements were used to verify the 21.4 percent efficiency, which is getting closer to the efficiency of non-flexible solar cells. Currently, the record for conversion efficiency for non-flexible solar cells made from crystalline silicon is 26.7 percent. Flexible solar cells are made on a polymer film using low-temperature co-evaporation to grow the thin-film Cu(In,Ga)Se2 semiconductor responsible for absorbing light.

Researchers on the project worked to optimize the layering and alkali dopants to achieve the efficiency improvement. Scientists also studied the effects of combined heat and light exposure after they processed the solar cells, discovering a boost in photovoltaic performance that remained stable even after several months.

The record 21.4 percent efficiency was verified by independent measurements conducted at Fraunhofer Institute for Solar Energy Systems ISE. Laboratory head Ayodhya N. Tiwari and his team of scientists have worked on flexible solar cells for over two decades. Over the years, they have been responsible for several records for efficiency, starting at only 12.8 percent efficiency in 1999.

By 2005, the team had moved the benchmark to 14.1 percent efficiency. Efficiencies continue to improve, reaching 17.6 percent in 2010, 18.7 percent in 2011, and 20.4 percent in 2013. By 2019, the efficiency record was 20.8 percent, and it has now moved to 21.4 percent.