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
- 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.
- Disorder creates new properties in compound semiconductorsAn international research team has demonstrated that the intrinsic disorder of the compound semiconductor CuInSnS₄ can be exploited to influence its optical properties. While the atomic vibrations also sense the local disorder, their response is averaged over many different local environments and therefore appear isotropic, as expected for a cubic crystal. In contrast, the optical excitations, known as excitons, are much more sensitive to the local arrangement of atoms. Surprisingly, they show a direction-dependent optical response even though the average crystal structure is cubic. These findings shed new light on the relationship between disorder and material properties, opening up new options for targeted 'disorder engineering' in optoelectronic and photocatalytic devices.
- Perovskite solar cells: Predictions of long-term stabilityReliable statements about the long-term stability of perovskite solar cells are still difficult to make. However, a new study by Dr Carolin Ulbrich’s team, published in the renowned journal Joule, highlights which methods are useful for this purpose and identifies areas where further research is needed.