Perovskite-silicon tandem solar cells achieve significantly higher efficiencies than silicon solar cells on their own. One particularly attractive method is co-evaporation of the perovskite precursor molecules on top of the silicon subcell. Scientists at HZB have analysed film growth on the nanoscale at BESSY II and found a new way to improve the quality of the perovskite layer: adding a thin seed layer of caesium chloride between the two sub-cells promotes uniform perovskite growth and suppresses the formation of undesired lead iodide at the interface.

We warmly invite you to our Open Day at the Lise Meitner Campus of the Helmholtz Centre Berlin (HZB) in Wannsee! A varied programme awaits you, featuring around 20 stations, guided tours, talks and hands-on activities for all.

Following predictions of the existence of fractons in quantum spin liquids by more general gauge field theories, researchers at HZB succeeded in detecting these quasi-particles also in a quantum solid-state model.

Prof. Dr Hatice Mutlu is the new professor of sustainable polymer chemistry at HIPOLE Jena, the Helmholtz Institute for Polymers in Energy Applications. On 17 August 2026, she visited the HZB campus in Berlin-Adlershof including the BESSY II lightsource and discussed future collaboration with researchers and the board of directors.

In condensed matter physics, "frustration" is a technical term: it describes a lattice geometry where competing magnetic interactions cannot all be satisfied simultaneously. This summer at HZB, I have been trying to *make* a frustrated material, and in the process I discovered that the word also describes rather accurately what happens when your sample explodes for the third time in a week.

When I arrived at HZB for the International Summer Student Programme, I expected to learn about chemistry, new instruments, and research techniques. During the welcome event, each of us received a small gift bag. Inside was a sticker that read, "Science is Diverse."

Every morning, as I step out of my room and feel the gentle Berlin sunshine on my face, I tell myself, “Today is a brand-new day.” Yet I never imagined that my research journey in Berlin, after joining HZB, would begin with an experimental result that did not go as expected.

Once upon a time, I was a kid who loved doing home experiments and unravel the explanation behind everyday phenomena. This passion and curiosity helped me to land up here in Berlin to work on the growth of crystalline materials at the wonderful campus of Helmholtz-Zentrum Berlin. But unlike many other stories, mine starts with an introductory question: What makes growing crystals fun and also challenging?

The first major challenge was facing my own initial lack of knowledge. Suddenly, I found myself surrounded by entirely new protocols: what can be touched with gloves, what is strictly glove-free, and how to safely move items through the space. As I did not fully know how new equipment operates, getting startled when something goes off-routine is inevitable.

Shaoxuan Wang has won a special prize in the Jugend Forscht competition for her project ‘Smart Capsules – intelligent microcapsules for glucose-dependent insulin release’. She designed the project as a “special achievement” for her A-levels. To carry out the experimental work, Shaoxuan was able to spend a further two weeks in the laboratory at the HZB Institute for Electrochemical Energy Storage, where she had completed a school internship two years earlier.