HZB Freigeist Fellow Dr. Annika Bande
HZB Freigeist Fellow: Dr. Annika Bande
Foto: Mirko Krenzel for VolkswagenStiftung
As of early October, the HZB is home to one of the Volkswagen Foundation's Freigeist Fellows: Dr. Annika Bande recently joined Prof. Dr. Emad Aziz' institute "Methods for Material Development". There she will build up her own junior research group with initially three PhD students.
The theoretical chemist's research focus is on ultrafast energy transfer processes. Central to her research is what's known as interatomic Coulombic decay (ICD) where an electronically excited state is produced within an atom. Upon returning to its ground state, the atom transfers its excess energy to a neighboring atom or molecule through electronic Coulomb interactions. During this process, the electrons interact with each other even over long distances.
These ultrafast energy transfer processes have already been studied both theoretically and experimentally, including at the HZB, in a number of variations in atomic and molecular systems. As part of her theoretical work, Annika Bande was able to demonstrate that ICD must also be taking place in semiconductor nanocrystals called quantum dots. Furnishing experimental evidence is what Bande and her team is hoping to accomplish as part of her work with Emad Aziz' institute. In a unique approach the scientists observe the electrons' motion in calculations and with various types of spectroscopy. From this they expect numerous direction-giving contributions to the investigation of chemical processes and to materials' research.
"Here at the HZB, I encountered optimal conditions for experiments being done that support my theory," Annika Bande says. The Aziz group has already conducted ICD investigations on atomic systems in aqueous solution. Adds Bande: "I'll be able to build on this experience while also broadening the instutute's spectrum as I'll be focusing my own work mostly on quantum dots." The scientist, who is currently working on earning the title of 'professor' at Heidelberg University, expects this will help her glean insights that will prove relevant to future solar cells, among other things.
The 790,000 Euro Volkswagen Foundation's Freigeist Fellowship provides funding for a five-year period during this initial phase. According to the Foundation, funding is granted to "exceptional researchers who have already earned their doctoral degrees and whose goal it is to move between established research areas while conducting cutting-edge, 'risky' science."
- Long-term stability for perovskite solar cells: a big step forwardPerovskite solar cells are inexpensive to produce and generate a high amount of electric power per surface area. However, they are not yet stable enough, losing efficiency more rapidly than the silicon market standard. Now, an international team led by Prof. Dr. Antonio Abate has dramatically increased their stability by applying a novel coating to the interface between the surface of the perovskite and the top contact layer. This has even boosted efficiency to almost 27%, which represents the state-of-the-art. After 1,200 hours of continuous operation under standard illumination, no decrease in efficiency was observed. The study involved research teams from China, Italy, Switzerland and Germany and has been published in Nature Photonics.
- Energy of charge carrier pairs in cuprate compoundsHigh-temperature superconductivity is still not fully understood. Now, an international research team at BESSY II has measured the energy of charge carrier pairs in undoped La₂CuO₄. Their findings revealed that the interaction energies within the potentially superconducting copper oxide layers are significantly lower than those in the insulating lanthanum oxide layers. These results contribute to a better understanding of high-temperature superconductivity and could also be relevant for research into other functional materials.
- Electrocatalysis with dual functionality – an overviewHybrid electrocatalysts can produce green hydrogen, for example, and valuable organic compounds simultaneously. This promises economically viable applications. However, the complex catalytic reactions involved in producing organic compounds are not yet fully understood. Modern X-ray methods at synchrotron sources such as BESSY II, enable catalyst materials and the reactions occurring on their surfaces to be analysed in real time, in situ and under real operating conditions. This provides insights that can be used for targeted optimisation. A team has now published an overview of the current state of knowledge in Nature Reviews Chemistry.