One year after announcing an efficiency record, Empa scientists have achieved a new mark of 22.2% for flexible CIGS solar cell on polymer film. Solar cells of this type are especially suited for applications on buildings, vehicles, satellites, airships, and mobile devices.
Empa researchers have – once again – improved the efficiency of CIGS flexible solar cells. Independently certified measurements revealed a power conversion efficiency of 22.2% to convert light into electricity, an improvement from their previous record value of 21.4%. To compare, the best efficiency of a rigid crystalline silicon solar cell is 26.7%. The team of Romain Carron, group leader in Empa’s Laboratory for Thin Films and Photovoltaics headed by Ayodhya N. Tiwari, presented their newest results at the 8th World Conference on Photovoltaic Energy Conversion (WCPEC-8) on 26 September 2022 in Milano, Italy.
These flexible solar cells are processed on a polymer film with the Cu(In,Ga)Se2 semiconductor layer that absorbs the light deposited by a low-temperature co-evaporation method. Empa scientist Shiro Nishiwaki modified the composition of the layer to improve the device performance and output voltage. “Two approaches explored to alloy the crystal delivered similar improvements in device performance”, said Romain Carron. Therefore, the findings can be transferred at industrial scale following different implementations, with equivalent outcomes. The solar cell efficiency of 22.2% was independently measured at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany.