A new world record for the efficiency of converting sunlight into electricity has been achieved by a tandem solar cell at the Helmholz Zentrum Berlin (HZB). Made up of a lower silicon cell and an upper perovskite cell, the cell is able to convert 32,5% of the incident solar radiation into electricity. The value is official, it has received confirmation from the ESTI certification institute in Italy and has already been added to the NREL's table of solar cell technologies (National Renewable Energy Lab) in the United States.
“The notable increase in the efficiency of tandem perovskite and silicon solar cells is a real breakthrough, which none of us could have imagined just a few months ago.” The Professor says it Steve Albrecht, who led the research.
All teams involved at HZB, especially the PV Competence Center and the HySPRINT Innovation lab have worked hard and achieved extraordinary results.
Steve Albrecht, HZB
New interface, new phase
The extraordinary success in the development of a highly advanced perovskite is the result of a brilliant intuition. Dr Silvia Mariotti and dr. Eike Kohnen worked to create an interface modification that reduces charge carrier recombination losses and used careful analysis to understand the unique properties of this modification. Thanks to the efforts of these scientists, this technology has been successfully implemented in tandem solar cells and further optimized with optical improvements.
Result? The highest PV (open circuit voltage) ever, the highest efficiency ever.
Perovskite/silicon tandem solar cell, continuous growth
The last decade has brought more and more efficiency records for this silicon perovskite solar cell, and it's a growth that appears to be accelerating. In the last 2 years, for example: 2021, the HZB team achieves an efficiency of 29,8% using periodic nanostructures. Summer 2022, theEPFL (Lausanne Polytechnic) in Switzerland presented a tandem cell with an efficiency of 31,3%. Today, less than 6 months later, we are at 32,5%.
It seems that the road is the right one
Imagine having a sort of super-solar cell that can capture and convert light energy across the visible light spectrum. This technological marvel is called a tandem solar cell and works thanks to two separate cells: a lower one made of silicon and an upper one made of perovskite.
The bottom cell is responsible for converting red and near-infrared light, while the top cell deals with blue light.
But how does this silicon perovskite solar cell work so effectively? Thanks to thin layers of special materials that help optimize the use of light and minimize electrical losses. Not only is it extraordinarily efficient, but also aesthetically pleasing, as you see in this illustration by Eike Köhnen/HZB.
Tandem Perovskite/Silicon Solar Cells, Now What?
Prof. Bernd Right, scientific director of HZB, expressed his satisfaction with this result: “We are very excited about the new value, because it shows that the tandem perovskite/silicon technology is very promising for contributing to a sustainable energy supply.”
He's right: the NREL chart clearly shows how the latest efficiency increases by HZB and EPFL have been truly spectacular.
We hope that as research and development progresses, this technology will become increasingly accessible and affordable for households and businesses around the world.
