From pv magazine Global
From pv magazine Germany
Scientists from Helmholtz-Zentrum Berlin (HZB) have once more broken the efficiency world record of tandem solar cells consisting of a silicon bottom cell and a perovskite top cell. The 32.5% efficiency record has been officially confirmed by the certifying institute European Solar Test Installation.
“This is a really big leap forward that we didn’t foresee a few months ago,” said Steve Albrecht from HZB’s perovskite tandem solar cell department. “All the teams involved at HZB, especially the teams from the PV Competence Center (PVcomB) and the HySPRINT Innovation Lab, have worked together excellently and with great dedication on this.
His team used an improved perovskite compound with a modificed surface. Silvia Mariotti and Eike Köhnen, both authors of the study, developed an interface modification in which charge recombination losses are largely suppressed. Furthermore, they applied special measurement methods to better understand the fundamental processes. These developments were then successfully transferred to tandem solar cells and combined with further optical improvements by Lea Zimmermann.
In recent years, there has been a continuous increase in efficiency values by various research institutions and photovoltaic companies worldwide. At the end of 2021, various teams from HZB achieved a then record value of 29.8% efficiency. To achieve this, they introduced special, periodic nanotextures into the solar cells. Then, this summer, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland, was able to significantly surpass that value again, achieving 31.3% efficiency with a certified tandem cell.
Now the highest value of 32.5% efficiency was again achieved by the HZB. “We are very pleased about the renewed significant leap in efficiency. This demonstrates the high potential of perovskite/silicon tandem solar cells to contribute to a sustainable energy supply and turnaround in the coming years,” said Albrecht.
HZB’s chief scientific officer, Bernd Rech, noted that “at 32.5%, the solar cell efficiency of the HZB tandems is now in ranges previously only achieved by expensive III/V semiconductors.”
Just last week, Meyer Burger signed a multi-year cooperation agreement together with several research institutes in Germany and Switzerland, including HZB. This involves the industrialization of perovskite tandem solar cells and modules.
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