Research institute Helmholtz-Zentrum Berlin (HZB) announced that its team has created a new tandem solar cell that can convert 32.5% of solar radiation into electricity, breaking the world record for tandem solar cells composed of silicon bottom cells and perovskite top cells.

Research institute Helmholtz-Zentrum Berlin (HZB) announced that its team has created a new type of tandem solar cell that can convert 32.5% of solar radiation into electricity, breaking the world record for a tandem solar cell composed of a silicon bottom cell and a perovskite top cell. Italy's certification body, the European Solar Testing Institute (ESTI), measured the tandem cells and officially confirmed this efficiency value, which is also included in the NREL solar cell technology chart maintained by the U.S. National Renewable Energy Laboratory.

HZB scientists have significantly improved the efficiency of perovskite/silicon tandem solar cells by using advanced perovskite compositions and making clever interface modifications. The team's lead authors, postdocs Silvia Mariotti, Ph.D., and Eike Köhnen, Ph.D., developed an interface modification to reduce charge carrier recombination loss and used detailed analysis to understand the properties of this interface modification. These developments, combined with further optical improvements, were successfully applied to tandem solar cells with the help of master's student Lea Zimmermann. Additionally, many more scientists and technicians helped develop and manufacture this tandem battery, leading to this success. In summary, the interface and optical modifications achieve the highest photovoltage ( open circuit voltage ) and set a new efficiency record for this fascinating tandem technology.

Over the past few years, and especially in the last month, the field has been very excited by the ongoing efficiency developments at various research institutions and companies: several teams at HZB achieved record efficiencies in late 2021, achieving an efficiency of 29.8% with periodic nanotextures. Most recently, in the summer of 2022, the Ecole Polytechnique Fédérale de Lausanne in Switzerland reported for the first time a certified tandem cell with an efficiency of over 30%, reaching 31.3%, a significant efficiency leap compared to 2021 values.

With a new certification value of 32.5%, HZB has once again set a new record. "We are very excited about the new value because it shows that perovskite/silicon tandem technology is very promising for contributing to sustainable energy supplies," said team leader Albrecht.

Professor Bernd Rech, scientific director of the HZB, said: "The HZB tandem solar cell has an efficiency of 32.5%, which was previously only possible with expensive III/V semiconductors."