The Fraunhofer Institute for Solar Energy Systems ISE, Soitec, CEA-Leti and the Helmholtz Center Berlin have achieved a record 44.7% efficiency using a new solar cell structure with four solar subcells.
The solar cells are being developed for use in concentrator photovoltaics applications. Each subcell absorbs a different range of wavelengths.
‘This four-junction solar cell contains our collected expertise in this area over many years,’ says Frank Dimroth, project leader at Fraunhofer ISE. ‘Besides improved materials and optimization of the structure, a new procedure called wafer bonding plays a central role. With this technology, we are able to connect two semiconductor crystals, which otherwise cannot be grown on top of each other with high crystal quality. In this way, we can produce the ‘