Revolutionary material science: Helmholtz High Impact Award for Novel Tandem Solar Cells
Eva Unger (3. v.l., Helmholtz-Zentrum Berlin) und Michael Saliba (4. v.l., Forschungszentrum Jülich) nehmen stellvertretend für ihr Forschungsteam den ersten Helmholtz High Impact Award von Helmholtz-Präsident Otmar D.Wiestler (2. v.l.), Bundesforschungsministerin Bettina Stark-Watzinger (5. v.l.) und Laudatorin Carla Seidel (1. v.l., BASF) entgegen. © Till Budde
A multidisciplinary team from Helmholtz-Zentrum Berlin (HZB) and Forschungszentrum Jülich (FZJ) is researching and improving novel tandem solar cells in order to bring them into application. For their approach and research achievements, Steve Albrecht, Antonio Abate and Eva Unger from HZB and Michael Saliba from FZJ received the High Impact Award on 27 September 2023. With the award, which comes with 50,000 euros in prize money, the Helmholtz Association and the Donors’ Association for the Promotion of Sciences and Humanities in Germany honour innovative approaches that have the potential to act as game-changers.
Current solar cells mostly use silicon to convert sunlight into electricity, but can only use a comparatively small part of the sun’s radiation for this purpose. The mineral perovskite, however, is much more efficient. Solar cells with a perovskite layer can absorb just as much light, but are up to 100 times thinner. This makes them particularly suitable for applications on curved surfaces, for example as foldable solar cells on cars or building facades. The layers can be produced from inexpensive materials and printed over large areas with little energy input using industrial technologies. If silicon and perovskite are combined, the performance can be increased even further. So far, however, these “tandem solar cells” face a number of challenges that prevent their widespread use: perovskites are not yet stable enough, they react sensitively to moisture or heat and disintegrate quickly. In addition, they contain lead – a substitute must be found for environmentally compatible application.
Steve Albrecht, Antonio Abate and Eva Unger from Helmholtz-Zentrum Berlin and Michael Saliba from Forschungszentrum Jülich are combining their expertise in electrical engineering, chemistry and physics to meet these challenges. With their research, they are making fundamental, pioneering contributions to enable the commercial and environmentally friendly production of perovskites for photovoltaics and other opto-electronic applications. With great success: Current research work by the team shows that perovskite silicon tandem solar cells can convert over 30 percent of solar energy into electricity so far. The team wants to make their research publicly accesible to the scientific community in order to make the results transparent and comparable.
The four researchers have now received the first Helmholtz High Impact Award for their approach and results. “The team led by Steve Albrecht and Eva Unger impressively demonstrates the strength of the Helmholtz Association: it combines different disciplines and works together across fundamental boundaries to tackle one of the greatest challenges of our time: energy transition. With their unique expertise and innovative strength, the four scientists are making a decisive contribution to advancing and shaping cutting-edge research in the field of photovoltaics. I warmly congratulate this young international team on their well-deserved High Impact Award,” says Helmholtz President Otmar D. Wiestler.
About the Helmholtz High Impact Award
Together with the Donors’ Association for the Promotion of Sciences and Humanities in Germany (Stifterverband für die Deutsche Wissenschaft), the Helmholtz Association is presenting the newly established “Helmholtz High Impact Award” for the first time this year. The award, which is endowed with 50,000 euros, recognises highly innovative interdisciplinary contributions that address a major challenge from science, industry or society. The focus is on new approaches that have the potential to act as a ‘game changer’ in a relevant problem area. The award ceremony took place at this year’s Helmholtz Annual Meeting on 27 September.
- Key technology for a future without fossil fuelsIn June and July 2025, catalyst researcher Nico Fischer spent some time at HZB. It was his sabbatical, he was relieved of his duties as Director of the Catalysis Institute in Cape Town for several months and was able to focus on research only. His institute is collaborating with HZB on two projects that aim to develop environmentally friendly alternatives using innovative catalyst technologies. The questions were asked by Antonia Rötger, HZB.
- Lithium-sulphur batteries with lean electrolyte: problem areas clarifiedUsing a non-destructive method, a team at HZB investigated practical lithium-sulphur pouch cells with lean electrolyte for the first time. With operando neutron tomography, they could visualise in real-time how the liquid electrolyte distributes and wets the electrodes across multilayers during charging and discharging. These findings offer valuable insights into the cell failure mechanisms and are helpful to design compact Li-S batteries with a high energy density in formats relevant to industrial applications.
- Self assembling monolayer can improve lead-free perovskite solar cells tooTin perovskite solar cells are not only non-toxic, but also potentially more stable than lead-containing perovskite solar cells. However, they are also significantly less efficient. Now, an international team has succeeded in reducing losses in the lower contact layer of tin perovskite solar cells: The scienstists identified chemical compounds that self-assemble into a molecular layer that fits very well with the lattice structure of tin perovskites. On this monolayer, tin perovskite with excellent optoelectronic quality can be grown, which increases the performance of the solar cell.