Last News Items
- Shape control in 2D molecular nanosheets by tuning anisotropic intermolecular interactions and assembly kinetics – Publication by A2 (Witte) and A8 (Koert/Dürr)22. March 2023 - 12:58
- LernortLabor awards Chemikum Marburg and Oe with LeLa-Prize 202314. March 2023 - 15:30
- SFB Successfully Held Winter School 2023 in Hirschegg, Kleinwalsertal13. March 2023 - 10:54
- Chemical Doping by Fluorination and Its Impact on All Energy Levels of π-Conjugated Systems – Publication by A2 (Witte) and A8 (Koert/Dürr)6. March 2023 - 15:52
- Poster Presentation Prize at DPT 2022 in Karlsruhe28. November 2022 - 07:47
- Dr. Philip Klement (B2 & B13) receives the dissertation prize of the Justus-Liebig-Universität Gießen25. November 2022 - 09:11
- Orbital Cinema and Cyclacenes: European Research Council awards two ERC Synergy Grants to SFB 1083 members25. October 2022 - 12:38
- Leopoldina awards Greve Prize to Kerstin Volz and Jürgen Janek20. October 2022 - 14:33
- F-Center Mediated Growth of Patterned Organic Semiconductor Films on Alkali Halides – Publication by A2 (Witte)3. October 2022 - 15:05
- Obituary for Prof. Dr. Stephan W. Koch – Nachruf für Prof. Dr. Stephan W. Koch23. September 2022 - 15:20
Engineering of Printable and Air-Stable Silver Electrodes with High Work Function using Contact Primer Layer: From Organometallic Interphases to Sharp Interfaces – Publication by A2 (Witte)/in News /by sfb1083
Felix Widdascheck, Daniel Bischof and Gregor Witte developed a robust method to prepare air-stable molecular contact primer layers allowing to reduce hole injection barriers of printable silver electrodes into organic semiconductors.
Contact engineering is an important issue for organic electronics as it allows to reduce charge carrier injection barriers. While the use of molecular contact primer layers was demonstrated in many concept studies for single crystalline model substrates, the processability of electrodes and their robustness in real devices must also be considered. Although silver electrodes can be printed using silver ink, their low work function and sensitivity to oxidation severely limits their use for printable organic electronics.
In this study Prof. Witte and his coworkers demonstrate that F6TCNNQ monolayers provide a reliable approach to engineer high work function silver electrodes, which is examined for Ag(111) as well as polycrystalline and silver ink substrates. Notably, upon multilayer growth, a pronounced intercalation of silver into the molecular adlayer occurs, yielding thermally stabilized organometallic interphases extending over the entire adlayer. It is shown that heating allows their controlled desorption leaving behind a well-defined monolayer that is further stabilized by additional charge transfer. Such primer layers enhance the work function to 5.5-5.6 eV and can even withstand air exposure but show no interdiffusion into subsequently deposited p-type organic semiconductor, hence validating their use for organic electronic devices.
Preparation scheme of F6TCNNQ layers on silver electrodes yielding well-defined, charge-transfer stabilized contact primer monolayers. Adapted from Widdascheck et al. (full citation see below) licensed by CC BY-NC-ND 4.0
For further information, please see the press release by the Philipps-Universität Marburg (in German).
F. Widdascheck, D. Bischof, G. Witte
Engineering of Printable and Air-Stable Silver Electrodes with High Work Function using Contact Primer Layer: From Organometallic Interphases to Sharp Interfaces
Adv. Funct. Mater. (2021) DOI:10.1002/adfm.202106687
Prof. Dr. Gregor Witte
SFB project A2
Tel.: 06421 28-21384
Momentum-forbidden dark excitons in WS2 – Publication by B6 (Höfer/Wallauer) and B9 (Malic)/in News /by sfb1083
In a publication in Nano Letters, Robert Wallauer and co-workers trace the early-stage exciton dynamics in a two-dimensional semiconductor and report first results on the ultrafast formation of momentum-forbidden dark excitons.
Excitons that form out of electrons and holes at different locations of the Brillouin zone, so-called dark excitons, play a key role for the optical properties of TMDC monolayers in general and for the formation of interlayer excitons in TMDC heterostructures, in particular. Whereas dark excitations are difficult to access by purely optical experiments they can be imaged directly in momentum space by time- and angle-resolved photoelectron spectroscopy [Madéo et al., Science 370, 1199 (2020)]. With the superior time-resolution of the momentum microscope operated by B6 (Höfer/Wallauer), the dynamics of formation of a dark KΣ exciton could now be resolved for the first time.
Reprinted with permission from Nano Lett. 2021, 21, 13, 5867–5873 Copyright 2021 American Chemical Society.
The formation process occurs on timescales where coherence between valence and conduction band play a major role. The short pump pulses of the experiment induce an optical polarisation in the K valley. This polarisation was found to decay and form bright and dark excitons in a few tens of femtoseconds after optical excitation. A fully microscopic theory by B9 (Malic) revealed the influence of the coherence on the formation process of the excitons, in excellent agreement with the experiment that could tune the excitation energy. The high quality WS2-samples for the measurements were provided by the Huber group in Regensburg, who earlier succeeded in probing momentum-indirect excitons via the intraexcitonic 1s-2p transition [Poellmann et al., Nat. Mater. 14, 889 (2015)].
Future experiments of this kind will address the role of dark excitons in the formation process of interlayer excitons. The excellent agreement between experiment and theory in this work holds great promise to investigate such charge transfer processes on a microscopic level.
R. Wallauer, R. Perea-Causin, L. Münster, S. Zajusch, S. Brem, J. Güdde, K. Tanimura, K.-Q. Lin, R. Huber, E. Malic, U. Höfer
Momentum-resolved observation of exciton formation dynamics in monolayer WS2
Nano Lett. (2021) DOI:10.1021/acs.nanolett.1c01839
Dr. Robert Wallauer
SFB 1083 project B6
Tel.: 06421 28 21406
Prof. Dr. Ermin Malic
SFB 1083 project B9
Tel.: 06421 28 22640
SFB 1083 extended by four more years/in News /by sfb1083
The German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) has granted the Collaborative Research Center SFB 1083 „Structure and Dynamics of Internal Interfaces“ 12.3 Million Euros for a third funding period from July 2021 to June 2025.
SFB 1083 was established at Philipps-Universität Marburg in 2013. It included a guest project from the Donostia-International Physics Center in San Sebastián, Spain. Meanwhile groups from the universities of Gießen, Leipzig and Münster as well as the Forschungszentrum Jülich participate in the center. From October 2013 to June 2021, Marburg and the participating institutions received DFG funding that amounts to 20.4 Million Euros. Together the researchers have published more than 330 scientific papers. For a report on the scientific activities from 2013 to 2019 see the activity report. A video clip, also available in German, explains the relevance of research on internal interfaces to the general public and highlights selected contributions of SFB 1083. With the new grant, SFB 1083 will be supported for altogether 12 years, the maximum funding period for a DFG Collaborative Research Center.
The 3rd SFB funding period will bring a number of changes. Kerstin Volz will become the new spokesperson and follow Ulrich Höfer, who initiated the SFB more than ten years ago and successfully guided it in the first and second funding period. Seven projects of the 2nd funding period will end, either because their principle investigators (PIs) reached retirement age, or because of a shift of scientific focus. Instead, eight new projects will become part of the center. Three of these new projects will be led by new PIs, namely Marina Gerhard, Jens Güdde and Ermin Malic. Altogether, SFB 1083 will consist of 19 scientific and three service projects in its last funding period. The projects will be led by 21 professors, senior scientists or junior group leaders. They will involve a total of about 80 scientists working in physics, chemistry and materials sciences.
Scientifically, the SFB will focus on a couple of new aspects in the coming years, such as the influence of the interface on lateral charge-carrier transport and the tailored synthesis at interfaces to design desired structures bottom-up. Research on interfaces of 2D materials, which started with the 2nd funding period in 2017, will be further extended. Last but not least, applications and devices will become more in to focus. The research on novel interface-dominated lasers will be intensified, including new material systems and emission wavelengths. Moreover, strong THz-emitters based on charge-carrier recombination across interfaces are included in the program due to promising results from the 2nd funding period. More applications and devices are envisioned, particularly as a result of research on hybrid organic/inorganic materials. Another important focus of the SFB will be on development and usage of sophisticated experimental methods, which allow unprecedented insights into processes at the nanoscale across interfaces.
Present spokesman Ulrich Höfer (left) and future spokeswoman Kerstin Volz in front of a poster introducing SFB 1083, Foto: Stefan Kachel.
See also Press Release of Philipps-Universität Marburg (in German) and the German Research Foundation (DFG) for more detail.
Prof. Dr. Kerstin Volz
Department of Physics and Materials Science Center
Tel: + 49 6421 28-22297
Biphenylene Network: A Nonbenzenoid Carbon Allotrope – Publication by A4 (Gottfried) and A8 (Koert/Dürr) in Science/in News /by sfb1083
Not graphene: Dr. Qitang Fan and coworkers of SFB 1083 discover new type of atomically thin carbon material
Carbon exists in various forms, of which graphene is one of the most astonishing. In this atomically thin material, each carbon atom is linked to three neighbors, forming hexagons arranged in a honeycomb network. Researchers in the SFB 1083 projects A4 (Gottfried) and A8 (Koert/Duerr) have now discovered a new carbon network, which is planar like graphene, but is made up of squares, hexagons, and octagons forming an ordered lattice. In collaboration with physicists from Aalto University in Finland, the unique structure was confirmed using high-resolution scanning probe microscopy methods. In addition, it was found that the electronic properties of the new material are very different from those of graphene.
Structure of the new carbon network. The upper part shows schematically the linking of the carbon atoms, forming squares, hexagons, and octagon. The lower part is an image of the network, obtained with atomic force microscopy. Adapted from Fan et al. (full citation see below) licensed by CC BY 4.0.
Biphenylene network, as the new material is named, is made from organic molecules on an atomically smooth gold surface. These molecules first form polymer chains, which consist of linked hexagons. A subsequent reaction connects these chains and forms the squares and octagons. An important feature of the chains is that they are chiral. Chains of the same type aggregate on the gold surface forming well-ordered assemblies, before they connect. This is critical for the formation of the new carbon material, because reaction between two different types of chains leads to the well-known graphene.
In contrast to graphene and other forms of carbon, the new material has metallic properties. Therefore, it can be used as conducting wires in future carbon-based electronic devices. The authors of the study are confident that their synthesis method will contribute to the discovery of further novel carbon networks. For now, their goal is to prepare larger sheets of the material and to study its interface-related properties.
For further information, please see the press release of the university of Marburg (available in German).
Q.T. Fan, L.H. Yan, M.W. Tripp, O. Krejči, S. Dimosthenous, S.R. Kachel, M.Y. Chen, A.S. Foster, U. Koert, P. Liljeroth, J.M. Gottfried
Biphenylene Network: A Nonbenzenoid Carbon Allotrope
Science 372 (2021) 852 DOI:10.1126/science.abg4509
Prof. Dr. Michael Gottfried
SFB 1083 project A4
Tel.: 06421 28 22541
Turning at top speed – Publication by B11 (Güdde/Höfer) in Nature/in News /by sfb1083
In collaboration with the group of Rupert Huber in Regensburg, Suguru Ito, Jens Güdde and Ulrich Höfer from the new SFB project B11 “Ultrafast dynamics of interface currents” demonstrate efficient high-order harmonic generation at the surface of a topological insulator by driving ballistic electron currents at THz frequencies.
On the surface of a topological insulator (colored surface), electrons (small blue sphere) move with quasi-relativistic speed. When a strong light wave accelerates electrons through the so-called Dirac point (apex of the cone), their velocity abruptly flips. The instantaneous change of velocity leads to the emission of broadband electromagnetic radiation (flash in the middle of the colored surface). Reprinted with permission from Nature (link see below).
In the conducting surface states of topological insulators electrons behave like massless particles, characterized by a linear dispersion (Dirac cone). Under the influence of an electric field, the electrons rapidly switch their direction of motion when their trajectories in momentum come close to the minimum of the cone, the Dirac point. At frequencies in the range of 25 to 35 THz, this is the case for electric field strengths of several MV/cm. It results in the emission of an ultrafast flash of light containing a broadband spectrum up to frequencies of 800 THz that can be analyzed with optical detectors.
This novel mechanism of high-harmonic generation is only possible because the spin-momentum-locking in the Dirac cone prevents efficient electron scattering. The resulting long scattering times of ~1 ps allow to drive strong ballistic electron currents as demonstrated previously with THz-ARPES (Reimann et al. Nature 2018). The emitted high-harmonic radiation has a characteristic polarization dependence related to the Berry curvature of the Dirac cone. Moreover, it can be shifted to arbitrary non-integer multiples of the driving frequency by varying the carrier-envelope phase of the driving field. These specific properties set it apart from HHG processes in bulk semiconductors (Hohenleutner et al. Nature 2015).
In the upcoming third funding period, SFB 1083 will utilize THz high-harmonic radiation generated in this way and exploit its characteristic properties to investigate electron currents at interfaces of topological insulators buried under protecting capping layers. For future device applications, it will be crucial to screen the unusual movement of Dirac electrons from the environment.
– Press release of the university of Regensburg (in English and German).
– Press release of the university of Marburg (in German).
– News of Physics Department, Philipps-Universität Marburg (in German).
– Homepage of the Huber group in Regensburg.
C.P. Schmid, L. Weigl, P. Grössing, V. Junk, C. Gorini, S. Schlauderer, S. Ito, M. Meierhofer, N. Hofmann, D. Afanasiev, J. Crewse, K.A. Kokh, O.E. Tereshchenko, J. Güdde, F. Evers, J. Wilhelm, K. Richter, U. Höfer, R. Huber
Tuneable non-integer high-harmonic generation in a topological insulator
Nature (2021) DOI:10.1038/s41586-021-03466-7
Prof. Dr. Ulrich Höfer
SFB 1083 project B6, B11
Tel.: 06421 28 24215
Quantitative Characterization of Nanometer-Scale Electric Fields via Momentum-Resolved STEM– Publication by A5 (Volz)/in News /by sfb1083
Andreas Beyer and coworkers achieved the determination and spatial resolution of electric fields at interfaces with the transmission electron microscope.
Adapted from Beyer et al. (full citation see below) licensed by CC BY-NC-ND 4.0.
Nanometer-scale built-in electric field are the basis of many modern (opto)electronic devices, such as solar cells, lasers or batteries. Optimization of these devices requires precise characterization of such fields at small length scales. With a fast pixelated-detector, A. Beyer and coworkers in SFB project A5 (Volz) acquire a 2D diffraction pattern for every real-space position of the impinging electron beam. In doing so, the momentum transfer of an electric field (or a charge) on the electron beam can be measured, and the electric field, which is invisible in “normal high angle annular dark field images”, can be calculated from the 4D data-set.
In this work, key characteristics, like doping concentration or polarity, of GaAs-based p-n junctions were quantitatively obtained by 4D scanning transmission electron microscopy (4DSTEM). The values are in excellent quantitative agreement with results from other techniques, which – of course – lack lateral resolution.
A. Beyer, M.S. Munde, S. Firoozabadi, D. Heimes, T. Grieb, A. Rosenauer, K. Müller-Caspary, K. Volz
Quantitative Characterization of Nanometer-Scale Electric Fields via Momentum-Resolved STEM
Nano Lett. (2021) DOI:10.1021/acs.nanolett.0c04544
Prof. Dr. Kerstin Volz
SFB 1083 project A5
Tel.: 06421 28 22297
Tracing orbital images on ultrafast time scales – Publication by B6 (Höfer/Wallauer) and A12 (Tautz/Bocquet/Kumpf) in Science/in News /by sfb1083
Robert Wallauer and coworkers combined a high harmonic laser source with an electron momentum microscope to record orbital images of the charge transfer at an organic/metal interface with femtosecond time resolution.
Excitation scheme for time-resolved photoemission orbital tomography. (b) Measured LUMO momentum maps for three selected delay times between pump and probe pulse. (c) Scheme of intramolecular and substrate-to-molecule excitation pathways. The LUMO pattern of the 0° molecule in (b) is seen to light up faster due to resonant HOMO-LUMO excitation than that of the 90° populated across the CuO Interface. From Wallauer et al, Science 371 (2021) 1056. Reprinted with permission from AAAS.
The microscopic charge-transfer dynamics across molecular interfaces is reflected in the population of electronic orbitals. These were, for the first time, directly monitored with ultrafast time resolution in a joint experimental effort of B6 (Höfer/Wallauer) in Marburg and A12 (Tautz/Bocquet/Kumpf) in Jülich. The experiment records the full two-dimensional intensity distribution of photoemitted electrons in momentum space in a femtosecond pump-probe scheme. Real-space electron distributions and photoemission momentum maps, called orbital tomographs, are related by a Fourier transform.
The model interface PTCDA/CuO/Cu(100) exhibits two distinct excitation pathways for the PTCDA molecule. The parallel component of the electric field of the pump pulse makes a direct HOMO-LUMO transition, while the perpendicular component transfers an electron from the metal across the atomically thin CuO spacer into the molecular LUMO. Once excited, the LUMO decays with a lifetime of 250 fs, independent of the excitation pathway. Real-space electron distributions and photoemission momentum maps, called orbital tomographs, are related by a Fourier transform (Photoemission Orbital Tomography, Wikipedia).
In the future, the new experimental capability is expected to facilitate the microscopic understanding of charge-transfer and exciton-formation processes at several other classes of organic heterointerfaces with unprecedented detail, including interfaces between 2D semiconductors and layered organic molecular structures.
Video: Ultrafast orbital tomography PTCDA molecules on a copper oxide surface are used as a probe. An electron of a molecule is excited by a laserpulse into another orbital and changes its spatial allocation. The electron in the excited orbital has a limited lifetime, which can be measured by ultrafast orbital tomography. Copyright: Sonderforschungsbereich 1083 / Till Schürmann
– Joint press release of the universities of Marburg and Graz and the FZ Jülich (available in English and German).
– News, Philipps-Universität Marburg (in German).
– News, Universität Graz, Österreich (in German).
R. Wallauer, M. Raths, K. Stallberg, L. Münster, D. Brandstetter, X. Yang, J. Güdde, P. Puschnig, S. Soubatch, C. Kumpf, F.C. Bocquet, F.S. Tautz, U. Höfer
Tracing orbital images on ultrafast time scales
Science 371 (2021) 1056 DOI:10.1126/science.abf3286
Prof. Dr. Ulrich Höfer
SFB 1083, project B6
Tel.: +49 6421 28-24215
Prof. Dr. Stefan Tautz
PGI, Experimental Physics, project A12
Tel.: +49 (0)2461 61-4561
New Two-Dimensional Materials by Design – Publication by A11 (Heine) and B2 (Chatterjee)/in News /by sfb1083
Johanna Heine and Sangam Chatterjee break boundaries in two-dimensional materials’ design towards enhanced light-harvesting and emitting capabilities of hybrid perovskites
Adapted from Klement et al. (full citation see below) licensed by CC BY-NC-ND 4.0.
Low-dimensional organic−inorganic perovskites synergize the virtues of organic perovskites and inorganic two-dimensional (2D) materials featuring intriguing possibilities for next-generation optoelectronics: they offer tailorable building blocks for atomically thin, layered materials while providing the enhanced light-harvesting and emitting capabilities. However, the quest for new materials is limited by the generally-accepted paradigm that atomically thin materials require covalent in-plane bonding.
The groups of Dr. Heine (A11) and Prof. Chatterjee (B2) within the SFB 1083 lift this apparent paradigm and report single layers of the 1D organic–inorganic perovskite [C7H10N]3[BiCl5]Cl. Its unique 1D–2D interface structure enables single layers and the formation of self-trapped excitons, which show white-light emission. The thickness dependence of the emission energy may enable facile color tuning for next-generation lighting and display technologies.
This class of materials enables interface-controlled device integration of brightly luminescent 1D and 0D hybrid perovskites and offers a promising pathway for the non-covalent functionalization of classical 2D materials through heterostructures.
For further information, please see the press release by the Philipps-Universität Marburg (in German).
P. Klement, N. Dehnhardt, C.‐D. Dong, F. Dobener, S. Bayliff, J. Winkler, D.M. Hofmann, P.J. Klar, S. Schumacher, S. Chatterjee, J. Heine
Atomically Thin Sheets of Lead‐Free 1D Hybrid Perovskites Feature Tunable White‐Light Emission from Self‐Trapped Excitons
Adv. Mater. (2021) DOI:10.1002/adma.202100518
Dr. Johanna Heine
SFB project A11
Tel.: 06421 28-22425
Prof. Dr. Sangam Chatterjee
SFB project B2
Tel.: 0641 99-33100
Vibrational Frequency Used as Internal Clock Reference to Access Molecule-Metal Charge-Transfer Times – Publication by A3 (Jakob)/in News /by sfb1083
Peter Jakob and Sebastian Thussing derived ultrafast charge-transfer times at molecule-metal interfaces using the vibrational oscillation period as an internal clock reference
Interfacial dynamical charge transfer at the molecule-metal interface, associated with non-adiabatic electron-vibron coupling leads to vibrational bands displaying characteristic asymmetric line shapes. Copyright by SFB1083.
Dynamical charge-transfer processes at molecule-metal interfaces proceed in the few fs timescale that renders them highly relevant to electronic excitations in optoelectronic devices. This is particularly true when electronic ground state situations are considered that implicate charge transfer directly at the fermi energy.
Prof. Jakob and Dr. Thussing showed that such processes can be accessed by means of vibrational excitations, with nonadiabatic electron-vibron coupling leading to distinct asymmetric line shapes. Thereby the characteristic timescale of this interfacial dynamical charge transfer can be derived by using the vibrational oscillation period as an internal clock reference.
P. Jakob, S. Thussing
Vibrational Frequency used as Internal Clock Reference to access Molecule — Metal Charge Transfer Times
Phys. Rev. Lett. 126 (2021) 116801 DOI:10.1103/PhysRevLett.126.116801
Prof. Dr. Peter Jakob
SFB project A3
Tel.: 06421 28-24328
Engineering of TMDC-OSC Hybrid Interfaces: The Thermodynamics of Unitary and Mixed Acene Monolayers on MoS2 – Publication by A2 (Witte) and A4 (Gottfried)/in News /by sfb1083
In a new publication in Chemical Science, projects A2 (Witte) and A4 (Gottfried) report on the intricate desorption characteristics of pentacene (PEN) and perfluoropentacene (PFP) monolayers on the MoS2 surface. Unitary molecular monolayers are thermally stabilized by entropy due to their high mobility rather than the organic/inorganic interface bond, which hampers the formation of close-packed and well-ordered monolayers.
Schematic representation of characteristic TPD traces and the temperature-dependent molecular diffusivity of unitary PEN films (left hand side) and the stabilized mixed PEN:PFP monolayer (right hand side) on MoS2 (Image: P. Dombrowski). Copyright by CC-BY-NC 3.0.
Van der Waals (vdW) bound hybrid heterosystems of inorganic two-dimensional materials (2DMs) and OSCs are currently receiving great attention due to their promising characteristics for the fabrication of flexible electronics and ultra-thin devices. While prototypical devices with 2DM-OSC hybrid heterostructures have been realized, the fundamental understanding of the 2DM-OSC interface is lacking. In their new study, the authors were able to thoroughly unravel the interplay of interface and intermolecular interactions and their effect on the structure and thermal stability of molecular monolayers.
Through temperature-programmed desorption (TPD) experiments, it was shown that the first molecular layers of PEN and PFP on MoS2 are thermally more stable than subsequent molecular layers in spite of an interface bond that is weaker than the molecular interlayer bond. This is possible due to an entropic stabilization that can only occur if the molecular adlayer is highly mobile. Thus, if the first molecular layer is only stabilized by its mobility, it cannot be well-ordered and close-packed even at low temperatures as low as 100 K. The high molecular diffusivity in the gas-like unitary PEN and PFP monolayers was identified by Monte-Carlo simulations: Intermolecular repulsion of intrinsic molecular electrostatic quadrupole moments, in combination with a weak substrate interaction, prohibits the formation of a condensed molecular monolayer.
By introducing attractive intermolecular interactions, condensation of the molecular films is favored. This was achieved in mixed monolayers of PEN and PFP that adopt a well-ordered stoichiometric 1:1 intermixture. In spite of a reduced mobility, the mixed monolayer is thermally stabilized with respect to the bulk substance due to the attractive intermolecular forces and can therefore be fabricated by selective multilayer desorption. This provides a promising prospect for the fabrication and subsequent study of well-defined 2DM-OSC interfaces for future studies within SFB 1083.
S.R. Kachel, P.-M. Dombrowski T. Breuer, J.M. Gottfried, G. Witte
Engineering of TMDC–OSC hybrid interfaces: the thermodynamics of unitary and mixed acene monolayers on MoS2
Chem Sci. (2021) DOI:10.1039/D0SC05633B
Prof. Dr. Gregor Witte
SFB 1083, project A2
Tel.: +49 6421 28-21 384