A group of scientists at the Helmholtz Zentrum Berlin (HZB) has produced a perovskite/silicon tandem cell measured at 29.15% efficiency, a new world record for the technology.
HZB previously held the efficiency record for PS/Si tandem cell efficiency at 25.5%, before UK/Germany based startup Oxford PV pushed further, producing a 28% efficient cell in late 2018. HZB’s new record has been officially certified by Germany’s Fraunhofer ISE, and the group says it will now be targeting the 30% barrier for this technology.
Optimizing the layers
Key to the group’s achievement were improvements in several of the cell layers. “We developed a special electrode contact layer for this cell in collaboration with the group of Prof. Vytautas Getautis (Kaunas University of Technology), and also improved intermediate layers“, explain Eike Köhnen and Amran Al-Ashouri, doctoral students at HZB.
The two went on to explain that the record breaking cell also featured an improved perovskite composition which increased stability improved the balance of currents delivered by the two cells, and an optimized silicon oxide top layer on the bottom Si cell, which improves optical coupling between the two.