Photo of the perovskite/silicon tandem solar cell. You can see the active bluish area in the middle of the wafer, which is enclosed by the metallic, silvery electrode

Berlin scientists break tandem solar cells efficiency record

Image credit: Johannes Beckedahl/Lea Zimmerman/HZB

Researchers at Helmholtz-Zentrum Berlin (HZB) have developed a tandem solar cell with 32.5 per cent efficiency, higher than the current world record.

The current record for the efficiency of tandem solar cells has been broken at HZB, certifying institute European Solar Test Installation (ESTI) in Italy has confirmed. 

Tandem solar cells consist of a silicon bottom cell and a perovskite top cell. In order to increase the technology's efficiency, the HZB team used an advanced perovskite composition with a smart interface modification.

Having developed an interface modification to reduce charge carrier recombination losses, the researchers applied detailed analysis to understand its specific properties.

Altogether, the interface and optical modifications enabled high photovoltages (open-circuit voltage) and resulted in the new record efficiency for tandem technology.

"This is a really big leap forward that we didn't foresee a few months ago. All the teams involved at HZB, especially the PV Competence Center and the HySPRINT Innovation lab teams have worked together successfully and with passion," said Professor Steve Albrecht, who is leading the team working on the project. 

The new efficiency value was in the NREL chart of solar cell technologies, maintained by the National Renewable Energy Lab, US (pictured below). 

Among the emerging technologies, silicon/perovskite tandem cells are at the absolute top.

Among the emerging technologies, silicon/perovskite tandem cells are at the absolute top. / NREL

Image credit: Among the emerging technologies, silicon/perovskite tandem cells are at the absolute top.

Over the last few years, researchers have made significant improvements to tandem solar cell technology, with a view towards achieving more sustainable energy sources.  

In 2021, various teams from HZB achieved a record efficiency value of 29.8 per cent that was realized by periodic nanotextures. More recently, in summer 2022, Switzerland's Ecole Polytechnique Fédérale de Lausanne reported a certified tandem cell above the 30 per cent barrier at 31.3 per cent, a remarkable efficiency jump over the 2021 value.

With the new certified value of 32.5 per cent, the record is again back at HZB.

"At 32.5 per cent, the solar cell efficiency of the HZB tandems is now in ranges previously only achieved by expensive III/V semiconductors. The NREL graph clearly shows how spectacular the last two increases from EPFL and HZB really are," said HZB's scientific director, Professor Bernd Rech. 

Albrecht added: "We are very excited about the new value as it shows that the perovskite/silicon tandem technology is highly promising for contributing to a sustainable energy supply."

Sign up to the E&T News e-mail to get great stories like this delivered to your inbox every day.

Recent articles