Flexible thin-film solar cells could make it possible to integrate photovoltaics into curved building façades or could be used as ultra-light energy sources on Zeppelins, electric aircraft, and drones. A team of scientists led by Ayodhya N. Tiwari from Empa is developing ultra-thin CIGS solar cells (copper indium gallium selenide) on flexible plastic foils that act as a substrate.
With the latest generation, they recently set an efficiency world record for flexible solar cells, Empa announced. The researchers were able to increase the efficiency to 20.8 percent, exceeding their own previous record of 20.4 percent. This puts them almost on a par with conventional silicon solar cells. On a rigid substrate, CIGS solar cells achieve an efficiency slightly in excess of 23 percent.
Extremely thin and lightweight
In addition to their flexibility, the CIGS solar cells developed by Romain Carron and his team from Empa offer the advantage of being extremely thin and lightweight. According to Romain Carron, the absorbing layer is only three to four micrometers thick, and the substrate approximately 35 micrometers. The cells weigh in at less than 100 grams per square meter.
As yet, the industrial production of flexible CIGS solar cells is still a hurdle, Romain Carron explained. “In the laboratory, we have so far only been able to produce squares of about five by five centimeters at a time.” The researchers intend to upscale this to enable commercialization. In the meantime, the ETH Zurich spin-off company Flisom is already marketing the first products based on this technology.
Written by: sda