HZB contributions to special edition on Ultrafast Dynamics with X-ray Methods
At the end of his contribution, Phillippe Wernet makes a great arch from the past (Opticae Thesaurus, 1572) of research with light to the future. © Wikimedia cc
In this theme issue leading researchers discuss
recent work on the ultrafast electronic and structural
dynamics of matter using a new generation of short
duration X-ray photon sources. © Royal Society
In the new special issue of the "Philosophical Transactions of the Royal Society of London", internationally renowned experts report on new developments in X-ray sources and ultrafast time-resolved experiments. HZB physicists have also been invited to contribute.
Almost 350 years after Isaac Newton's ground-breaking paper "Theory of Light and Colors (1671)", the world's oldest scientific journal “Philosophical Transactions” is now once again dedicated to light. The special issue on “Ultrafast Dynamics with X-ray Methods” is aimed at researchers who want to investigate biological, chemical or physical processes and obtain an overview of new developments in light sources and the methods available there. Dynamic processes in materials can be analyzed with high resolution and short pulses at X-ray light sources using ultrafast methods.
Femtoslicing and BESSY VSR
The special issue provides a comprehensive overview of current advances in the generation of ultra-short X-ray pulses by light sources such as Free Electron Lasers (FELs), High Harmonic Generation (HHG) laser sources and synchrotron radiation sources. An article in collaboration with Dr. Karsten Holldack, HZB, presents FEls and Laser sources but also classifies storage ring based methods such as “Femtoslicing” and BESSY VSR. These methods combine highly brilliant synchrotron light with a special time structure and thus allow to address unique experimental questions that cannot be answered at other sources. This complements and expands the portfolio of accelerator-based sources.
Ultra fast spectroscopy for photochemistry
An important contribution is dedicated to photochemistry, an area that focuses on processes such as photosynthesis, the dynamics of which are still largely unexplored. Using ultra-fast spectroscopy at FELs, HHG sources or at the synchrotron with BESSY VSR, methods are now available to measure in detail, for example, excitations of metallo-proteins and the subsequent reactions ; such experiments provide data that are indispensable, for example, for understanding photocatalysis of solar fuels. This article was written by Prof. Dr. Philippe Wernet, formerly a senior scientist at the HZB, and now a professor at Uppsala University, Sweden.
To the publications:
Measurement of ultrafast electronic and structural dynamics with X-rays; J. P. Marangos (ed.)
doi: 10.1098/rsta/377/2145
Recent Advances in Ultrafast X-ray Sources; Robert Schoenlein, Thomas Elsaesser, Karsten Holldack, Zhirong Huang, Henry Kapteyn, Margaret Murnane, Michael Woerner
doi: 10.1098/rsta.2018.0384
Chemical interactions and dynamics with femtosecond X-ray spectroscopy and the role of X-ray free-electron lasers; Philippe Wernet
doi: 10.1098/rsta.2017.0464
- Perovskite triple-junction solar cells: Even more efficient with GO/SAM bilayersPerovskite semiconductors efficiently convert sunlight into electrical energy; they are also inexpensive and extremely lightweight. A team at HZB has developed a triple-junction solar cell comprising different perovskite semiconductors, with a novel bilayer of graphene oxide (GO) and a self-assembled monolayer (SAM) as the hole conductor. This bilayer significantly increases both efficiency and long-term stability. The efficiency of the novel perovskite triple-junction solar cell is 27.3% and shows hardly any decline even after more than 770 hours of operation. The study has been published in the renowned journal Joule.
- Magnetic imaging: Micro-flowers increase the local magnetic fieldMaterials with magnetic nanostructures have many potential applications such as in spintronics. To explore such materials, nanoscale magnetic-sensitive imaging techniques are very useful, but up to now only weak magnetic fields could be applied during the imaging process. Now an international collaboration led by Dr. Sergio Valencia, HZB, has developed an approach that overcomes this limitation. The team designed tiny magnetic flux concentrators (MFCs), into which the sample is placed. The geometry of the MFCs resembles a flower with a number of petals which focus the applied magnetic field into its center. This greatly expands the magnetic field range available during imaging, and so the range of magnetic systems that can be investigated. The micro-flowers, enhancing magnetic fields locally, can find application in different nanometric magnetic microscopy techniques.
- CIGS-perovskite tandem cell achieves record efficiency of 25.5 %A Berlin-based team from HZB and Center for the Science of Materials Berlin (CSMB) at the Humboldt-Universität zu Berlin has set a new record for a tandem solar cell. Using a combination of a CIGS semiconductor layer and perovskite, along with several optimised intermediate layers, they were able to convert 25.5% of sunlight into electrical energy. The previous record for this combination of materials and this size of cell stood at 24.6%. The new record has been certified and is visible in the prestigious Solar Cell Efficiency Tables (the "Green Tables"), which serve as the definitive ledger for the global photovoltaic community.