News
Last News Items
Probing electron-hole Coulomb correlations in the exciton landscape of a twisted semiconductor heterostructure – Publication by B9 (Malic) in Science Advances7. February 2024 - 12:00
Heteroepitaxy in Organic/TMD Hybrids and Challenge to Achieve it for TMD Monolayers: The Case of Pentacene on WS2 and WSe2 – Publication by A2 and B58. January 2024 - 10:06
Layer-by-layer deposition of organic molecules controlled by selective click reactions – Publication by A8 (Koert/Dürr) in Chemistry of Materials 23. December 2023 - 14:48
Enhanced Circular Dichroism and Polarized Emission in an Achiral, Low Band Gap Bismuth Iodide Perovskite Derivative5. October 2023 - 11:25
34. Erfinderlabor: Scientific curiosity of the next Generation1. August 2023 - 14:34
Measuring spatially-resolved potential drops at semiconductor hetero-interfaces using 4D-STEM– Publication by A5 (Volz) in Small Methods28. May 2023 - 14:07
Interface engineering of charge-transfer excitons in 2D lateral heterostructures – Publication by B9 (Malic) in Nature Communications9. May 2023 - 09:27
Electrical control of hybrid exciton transport in a van-der-Waals heterostructure – Publication by B9 (Malic) in Nature Photonics20. April 2023 - 09:46
When electrons dress up in light – Publication by B11 (Güdde/Höfer) in Nature12. April 2023 - 16:21
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
Lightwave valleytronics in WSe2 – Publication by B4 (SW Koch) in Nature
/in News /by sfb1083As part of their ongoing theory-experiment collaboration, members from project B4 (group of Prof. S.W. Koch) jointly with colleagues from Regensburg (group of Prof. Huber) and the University of Michigan (former co-PI in B4 Prof. Kira) demonstrate how to control and manipulate the quantum states of optically excited electrons in modern quasi-two dimensional semiconductor materials. In particular, they show that the valley pseudo-spin in a tungsten diselenide system can be switched at ultrafast speeds by applying an intense light field.
Energy-landscape in a WSe2-semiconductor depicted as blue hills. Electrons are accelerated from one valley to the next (yelloworange) with the colored arrows indicating change of the valley-pseudospin. (Ill.: F. Langer, Univ. Regensburg; use only in context of paper published).
In today’s information technology, quantum effects still play a mostly supporting role. This should change in the future, as research into quantum information technology paves the way towards efficient storage, processing and communication – eventually replacing “Moore’s law” with its own. The basis are robust and quickly switchable electronic states provided by the so-called “valley pseudospin” that can be changed when energized electrons are optically driven between distinct energetic valleys in the hexagonal layered materials.
This controlled ultrafast switching between the occupation of different bandstructure minima provides an important step in the new area of light driven electronics, opening the field for lightwave valleytronics. Ultimately this may become important in developing room-temperature quantum signal processing.
Publication
F. Langer, C. P. Schmid, S. Schlauderer, M. Gmitra, J. Fabian, P. Nagler, C. Schüller, T. Korn, P. G. Hawkins, J. T. Steiner, U. Huttner, S. W. Koch, M. Kira & R. Huber, Lightwave valleytronics in a monolayer of tungsten diselenide,
Nature 557 (2018) 76-80, DOI: 10.1038/s41586-018-0013-6
See also press release (
Uni Marburg in German;
UMICH Ann Arbor in English), a video (UMICH Ann Arbor) and articles
in
Oberhessische Presse and Rhein-Neckar-Zeitung.
Contact
Prof. Dr. Stephan W. Koch
Dept. of Physics, Philipps-Universität Marburg
SFB 1083 Project B4 (SW Koch)
Tel. +49 (0)6421 28-21336
Email: Stephan.W.Koch@physik.uni-marburg.de
JPCM Special Issue on Internal Interfaces
/in News /by sfb1083Copyright by IOP Publishing. Reproduced with permission. All rights reserved.
The Journal of Physics: Condensed Matter (JPCM) has announced a Special Issue on Internal Interfaces. Guest editors are Michael Gottfried and Ulrich Höfer from SFB 1083 in Marburg.
This special issue will collect up-to-date research related to the structural characterization of internal interfaces between solid materials as well as investigations addressing electronic coupling and dynamics of charge transfer processes at heterostructures. Original articles covering fundamental or applied aspects of research on internal interfaces are welcome.
Articles can be submitted between May and September 2018. For more information see the special issue website.
Pedro Echenique is awarded honorary membership of European Physical Society (EPS)
/in News /by sfb1083Professor Echenique was elected by the Council 2018 in Paris for his outstanding achievements as a scientist in the field of Surface Physics, Attophysics, Interaction of charges and radiation with matter and Many-body Physics and for his contributions as an exceptional and tireless advocate of outreach, dissemination and public awareness of physics, notably the creation and development of Passion for Knowledge, which is a large-scale public outreach event in Donostia, Basque Country, promoting science as the driving force behind technological progress and the foundation of human culture.
https://www.epsnews.eu/2018/04/eps-distinctions-2018/
Kenta Kuroda receives Young Scientist Award of the Physical Society of Japan
/in News /by sfb1083-ANKenta Kuroda receives Young Scientist Award of the Physical Society of Japan (Photo: Univ. of Tokyo).
We congratulate Dr. Kenta Kuroda, former JSPS fellow and guest scientist of project B6 (Höfer) on receiving the prestigious “Young Scientist Award” of the Physical Society of Japan for his “Research on spin-polarized surface electrons and their light control in topological insulators using photoelectron spectroscopy”.
The prize is awarded annually in recognition of an outstanding young researcher who promises to make a lasting contribution to the future of physical research in Japan. It was given to Dr. Kuroda at the Annual Meeting of the Physical Society of Japan held at the Tokyo University of Science on March 22, 2018.
In work conducted in Marburg in 2014-15 [1] and continued at the Institute for Solid State Physics of the University of Tokyo [2], he demonstrated by precise measurements of topological insulators using photoelectron spectroscopy that light is able to control the spin-polarized Dirac surface electrons. In previous research conducted as a PhD student at Hiroshima University Kuroda had already characterized the electronic structure of these special surface electrons as Dirac particles [3].
Publications
Generation of Transient Photocurrents in the Topological Surface State of Sb2Te3 by Direct Optical Excitation with Midinfrared Pulses
Phys. Rev. Lett. 116, 076801 (2016).
Coherent control over three-dimensional spin polarization for the spin-orbit coupled surface state of Bi2Se3
Phys. Rev. B. 94, 165162 (2016).
Hexagonally Deformed Fermi Surface of 3D topological Insulator Bi2Se3
Phys. Rev. Lett. 105, 076802 (2010).
Student Poster Day
/in News /by sfb1083SFB’s student speaker organized a “Meet and Greet” Poster Event for all the new – and old – PhD-students and young postdocs of the second funding period and in particular the new members from Gießen, Jülich and Münster to meet the others from Marburg.
With snacks and beer to break the ice, it was a lively 3 hours of dicussion and scientific exchange across project-boundaries and disciplinary constraints. More opportunities for inner-SFB networking will arise at the 2nd SFB/GRK-Seminar in September and the 3rd Winter Student Seminar in February 2019.
Dynamics of charge transfer excitons at PFP/PEN interfaces – Publication by B2 (Chatterjee) and A2 (Witte)
/in News /by sfb1083Members from projects B2 and A2 explored the dynamics of charge-transfer excitons at the internal interface in heterostructures of the organic donor-acceptor molecules pentacene and perfluoropentacene.
Reprinted with permission from A. Rinn et al, 2017, 9, 48, 42020–42028. Copyright 2017 American Chemical Society.
Organic photovoltaics is a vivid research field as it promises the fabrication of large scale and thin film devices on flexible supports. One of the key challenges is the separation of optically excited bound electron-hole pairs, so-called excitons. Of particular relevance are charge-transfer (CT) excitons at donor-acceptor interfaces with the electron in the acceptor and the hole in the donor molecule as they are prime candidates as intermediaries for charge separation. Studying these CT excitons in state-of-the-art devices is challenging as these consist of blends of molecular donors and acceptors in order to provide maximum internal interface area. The resulting, complex interface geometry structure hampers microscopic characterization of such CT-excitons and, in particular, denies a well-defined correlation of the electronic properties with the molecular packing at the interface. Hence, detailed studies on the underlying physical mechanism of charge-separation in organic photovoltaics rely on highly-ordered model heterojunctions.
In the present study, the researchers combine their expertise in the fabrication of such highly ordered crystalline molecular heterostructures with precise, time-resolved optical microspectroscopy to study the energetics and dynamics of CT-excitons at donor-acceptor interfaces for selected pentacene / perfluoropentacene heterostructures. Based on previous work, various molecular heterostructures with different molecular orientation are realized and further compared with the dynamics of blends, i.e., completely intermixed heterostructures, as well as the respective pure materials.
The spatial separation of electrons and holes in the CT-excitons leads to extended lifetimes compared to the pristine species. Intriguingly, the energetics reveal that the common description of such excitons based on a straight-forward orbital picture as a mere linear combination of the involved individual constituents is insufficient and a more intricate description of CT-excitons is needed. The present study provides the first experimental data systematically investigating such excitations in highly-ordered crystalline molecular heterostructures, which will enable further theoretical calculations on the involved electronic effects.
Publication
Andre Rinn, Tobias Breuer, Julia Wiegand, Michael Beck, Jens Hübner, Robin C. Döring, Michael Oestreich, Wolfram Heimbrodt, Gregor Witte, Sangam Chatterjee, Interfacial Molecular Packing Determines Exciton Dynamics in Molecular Heterostructures: the Case of Pentacene – Perfluoropentacene,
ACS Applied Materials & Interfaces, (2017) DOI: 10.1021/acsami.7b11118
Contact
Prof. Dr. Sangam Chatterjee
Institute of Experimental Physics I, Justus-Liebig-University Giessen
SFB 1083 Project B2 (Chatterjee)
https://www.uni-giessen.de/ipi
Tel. +49 (0)641 99-33100
Email: Sangam.Chatterjee@physik.uni-giessen.de
Prof. Dr. Gregor Witte
AG Molekulare Festkörperphysik, Philipps-Universität Marburg
SFB 1083 Project A2 (Witte)
https://www.uni-marburg.de/sfb1083/projects/A2
Tel. +49 (0)6421 28-21384
Email: Gregor.Witte@physik.uni-marburg.de
Alexander Lerch (B6) receives poster-prize at ESPMI9 in Singapore
/in News /by sfb1083Alexander Lerch, PhD-student in project B6 (Höfer/Wallauer) received an “ACS Nano Poster Prize” for his presentation at the international workshop EPSMI9 in Singapore.
In his contribution, Alexander Lerch presented new insights into carrier dynamics at metal-molecule interfaces investigated by means of time resolved two-photon photoemission (2PPE). The experimental results obtained in model systems consisting of well-defined molecular layers deposited on single crystaline metal substrates highlight the capability of interface-related electronic states to mediate charge transfer.
Poster “Interface-specific mechanisms of charge transfer at metal-molecule contacts”
A. Lerch 1, F. Schiller 1,2, U. Höfer 1
1 Philipps-Universität-Marburg
2 Centro de Física de Materiales, San Sebastián, Spain
9th Electronic Structure and Processes at Molecular-Based Interfaces, 8-10. Nov. 2017, Nat. Univ. of Singapore
Klaus Stallberg (B6) is awarded dissertation-prize at TU Clausthal
/in News /by sfb1083Congratulations to Dr. Klaus Stallberg, who recently joined project B6 (Höfer/Wallauer) as a postdoc, for being awarded a dissertation-prize.
In his thesis Klaus Stallberg investigated thin porphyrin films and plasmonic silver structures with multi-photon photoemission electronmicroscopy (nP-PEEM). Based on energy-resolved, time-resolved and laterally resolved nPPE experiments he porposed a model for the complex electronic excitation and relaxation processes in porphyrin films and was able to show how a thin porphyrin layer affects the dispersion of plasmons propagating on an extended silver island.
For these investigations he received one of three prizes (Förderpreis 1000 EUR) of the Friends of TU Clausthal (Verein von Freunden der Technischen Universität Clausthal e.V.).
Since July 2017 Klaus Stallberg explores the dynamics of charge transfer processes at interfaces of organic heterostructures by means of time-resolved two-photon photoemission in the framework of project B6 (Höfer/Wallauer).
Link to dissertation on TU Clausthal server.
TU Clausthal press release.
The sublime utility of useless science – Special Colloquium with Prof. Pedro Echenique
/in News /by sfb1083Kick-starting the new funding-period, SFB 1083 proudly welcomes Prof. Dr. Dr. h. c. mult. Pedro M. Echenique from the Donostia International Physics Center in San Sebastián (Spain) and principal investigator in former guest project GP1 of the first funding periode for a special colloquium on “The sublime utility of useless science”.
…how science and innovation stand at the center of any successful strategy for the long-term economic development of a country, and how it is even more important and profitable to create an atmosphere for fundamental research rather than to define specific targets…
Professor Echenique is a theoretical physicist at the University of the Basque Country in San Sebastián, Spain, and an external member of SFB 1083 who has continuously engaged himself as a vivid supporter of fundamental science. From 1980 to 1984, he served as a minister for education and culture in the first Basque government elected after the Spanish transition to democracy. In recognition of his fundamental scientific contribution on the interaction of electrons and ions with solids and solid surfaces, Echenique received prestigious prizes, including and the Prince of Asturia Award and the Max Planck Research Prize. In 1999, he founded the Donostia International Physics Center (DIPC), a center of excellence that receives significant funding from private donations. In 2016, his institute received an award by the European Physical Society (EPS), recognizing not only the outstanding contributions of the DIPC in the field of condensed matter physics and materials science, but also for its numerous, successful activities in the outreach and communication of science.
Further information:
Announcement of Professor Echenique’s talk /Ankündigung auf Deutsch
Homepage of the Donostia International Physics Center (DIPC)
Curriculum vitae of Professor Echenique
Johannes Reimann (Project B6) receives Poster-Award at ICFSI-16
/in News /by sfb1083We congratulate Johannes Reimann, PhD-student in the research group of Prof. Höfer, who received a poster-prize for his outstanding presentation at the 16th International Conference on the Formation of Semiconductor Interfaces (ICFSI-16) in Hannover.
The work was undertaken within the DFG priority program “Topological Insulators: Materials-Fundamental Properties-Devices” (SPP 1666) and in close collaboration with project B6 of Prof. Höfer.
ICFSI-16 is part of a biannual conference series primarily focused on phenomena at surfaces, interfaces, and nanostructures that are of strong current interest, ranging from characterization at the atomic scale to prospects of applications.
Poster “Optical control of ultrafast currents in the topological surface state of Sb2Te3” by J. Reimann1, K. Kuroda1,2, K. A. Kokh3, O. E. Tereshchenko3, A. Kimura4, J. Güdde1, U. Höfer1 (1 Philipps-Universität-Marburg, 2 University of Tokyo, 3 Russian Academy of Sciences and Novosibirsk State University, 4 Hiroshima University) – 16th International Conference on the Formation of Semiconductor Interfaces (ICFSI-16) July 02 – 07, 2017, Hannover, Germany.