O Helmholtz Research Institute (HZB) established a world record: developed a new type of tandem solar cell that converts 32,5% of incident solar radiation into clean electrical energy.
The result was confirmed by European Solar Test Installation certification institute, in Italy. “This is truly a major breakthrough that we did not anticipate a few months ago. All teams involved in HZB worked together excellently and with great dedication”, said professor Steve Albrecht.
According to the entity, the team used an improved perovskite compound and a sophisticated surface modification. Postdocs Dr. Silvia Mariotti and Dr. Eike Köhnen, both first authors of the study, developed an interface modification in which charge recombination losses are largely suppressed.
Furthermore, they applied special analytical measurement methods to better understand fundamental processes. These developments were then transferred to tandem solar cells and combined with other optical improvements by master's student Lea Zimmermann.
Fast progress
In recent years there has been a continuous increase in efficiency values by several research institutions and solar energy companies around the world. “The last few months in particular have been very exciting: several HZB teams managed to achieve a record value of just under 30% (29,8%) at the end of 2021,” they reported.
To do this, they introduced special periodic nanotextures into the photovoltaic cells. In the summer of this year, the Ecole Polytechnique Fédérale de Lausanne, in Switzerland, managed to significantly exceed this figure again and was the first in the world to break the 30% barrier with a tandem cell certified with 31,3% efficiency.
Now, however, the maximum value of 32,5% is back in HZB. “We are very pleased with the new significant leap in efficiency. This shows the high potential of perovskite/silicon tandem solar cells to contribute to sustainable energy supply and the turning point in the coming years,” emphasized Albrecht.
Professor Bernd Rech, Scientific Director of the HZB, adds: “At 32,5%, the efficiency of the HZB tandem solar cell is now in ranges that were previously only achieved by expensive III/V semiconductors.”
What is a tandem solar cell?
Eduardo Mendes, R&D (Research and Development) supervisor at BYD Brasil, explained that, instead of using a single absorber layer formed by silicon or perovskite, for example, researchers discovered how to manufacture a double device, connecting the two in series ( in tandem), a scheme in which they work cooperatively, taking advantage of a greater range of the solar spectrum.
"Tandem cells deliver a faster result, with superior efficiency and takes advantage of the entire silicon chain in a shorter space of time than just perovskite worked alone”, he highlighted.
