Shape control in 2D molecular nanosheets by tuning anisotropic intermolecular interactions and assembly kinetics – Publication by A2 (Witte) and A8 (Koert/Dürr)

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In a new publication in Nature Communications, the groups of Gregor Witte (A2) and Ulrich Koert (A8) introduce a new concept that allows to control the mesoscopic shape of 2D molecular islands grown on weakly interacting substrates like MoS2 without affecting their nanoscopic packing motif.

Schematic representation of the growth and desorption kinetics of partially fluorinated pentacene nanosheets (Image: Maximilian Dreher, Copyright CC-BY 4.0)

Hybrid heterostructures of transition metal dichalcogenides (TMDCs) and molecular materials combine the excellent charge carrier transport properties of TMDCs with the possibility to tailor optoelectronic properties of organic semiconductors. Since molecular materials often decompose upon exposure to radiation, lithographic patterning techniques established for inorganic materials are usually not applicable for the fabrication of organic nanostructures. Compared to metallic substrates, where molecule-substrate interactions dominate the mutual intermolecular interactions, the latter becomes decisive for adlayers grown on weakly interacting substrates such as TMDCs. This fact can be used to employ electrostatic Coulomb interactions between specifically designed, partially fluorinated pentacene derivatives to tailor the intermolecular interactions.

Using scanning tunneling microscopy, Maximilian Dreher and Pierre Dombrowski found that while the anisotropic attractive Coulomb forces between partially fluorinated pentacenes determine the molecular packing motif, distinctly elongated nanosheets are formed at submonolayer coverage, where the direction of elongation is different between directly grown nanosheets and those prepared by partial desorption of a complete molecular monolayer. Using kinetic Monte Carlo (MC) simulations, it could be shown that the nanosheet formation is not driven by an energy minimization of the intermolecular interactions. Instead, the sheet shape is determined by the evolution of individual molecules either attaching to or detaching from the nanosheets. Further MC simulations demonstrate statistically, that their formation is determined i) by the geometrical anisotropy of the intermolecular interactions and ii) by the kinetics during growth and desorption. By comparison of the behavior of differently fluorinated molecules, both experimentally and computationally, important design rules for molecules could be derived.

Publication

M. Dreher, P.M. Dombrowski, M.W. Tripp, N. Münster, U. Koert, G. Witte
Shape control in 2D molecular nanosheets by tuning anisotropic intermolecular interactions and assembly kinetics
Nat. Comm. 14 (2023) 1554 DOI:10.1038/s41467-023-37203-7

Contact

Prof. Dr. Gregor Witte
Philipps-Universität Marburg
SFB 1083 project A2
Tel.: 06421 28-21384
EMAIL

LernortLabor awards Chemikum Marburg and Oe with LeLa-Prize 2023

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On the LernortLabor conference, the Chemikum and the Oe project of SFB 1083 was awarded with the LeLa 2nd price for the outstanding experiments and educational offer in Marburg.

Award ceremony – Lernort Labor Meeting, Göttingen (v.l. Dr. Andreas Paetz (BMBF), Erich Weber (LK MR-BID), Luise Cleres, Dr. Marion Enßle, Dr. Ina Budde, Dr. Christof Wegscheid-Gerlach (alle Chemikum Marburg), Dr. Andreas Kratzer (LeLa) (Foto: Christoph Mischke, Goettingen).

Pupil labs are central facilities in many educations and STEM (Science, Technology, Engineering and Mathematics) regions. They are constantly offering new experiments, trying out new methods of teacher education and using creative methods. This year, the educational offer of the Chemikum Marburg and the SFB 1083 was awarded the LernortLabor (LeLa) 2nd Prize in the category “Experiment of the Year”. The jury judged the format to be an innovative and admirable approach. The LeLa Prize recognizes outstanding achievements by school laboratories and school laboratory networks.

The awarded experiment is a two-hour experimental workshop for young people from grade 9 and upwards and the general public, which focuses on the properties of hydrogen, its production, storage and ultimately the conversion, e.g. in fuel cells. SFB 1083-related experiments, like using solar cells for hydrogen production or the detection of hydrogen by means of suitable detectors, rounded off the overall very good impression of the Chemikum and the Oe project.

Poster presentation (Foto: Chemikum Marburg).

At the conference, the activities of the Oe project were also presented in detail with a poster contribution and within the lecture session “Science Communication, Public Relations and Research: School Labs in DFG-funded Projects”.

LernortLabor – Bundesverband der Schülerlabore e.V. represents extracurricular learning venues that focus on independent work, discovery, research and development in an authentic environment, such as a laboratory or workshop. LernortLabor is the leading lobby group for school laboratories in German-speaking countries and an expert contact for its members, stakeholders in the education scene as well as for politics, business and interested society.

Contact

Dr. Christof Wegscheid-Gerlach
Philipps-Universität Marburg
SFB 1083 project Oe
Tel.: 06421 28-25843
EMAIL

SFB Successfully Held Winter School 2023 in Hirschegg, Kleinwalsertal

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After being postponed due to the pandemic situation, SFB 1083’s Winter School 2023 took place in presence from February 27th to March 3rd, 2023 at Marburger Haus in Hirschegg, Kleinwalsertal, Austria.

Groupfoto of the 40 participants. (Foto: Maximilian Dreher)

The 40 participants came from four collaborating institutions (33 from Philipps-Universität Marburg, four from Justus-Liebig-Universität Gießen, two from Universität Leipzig and one from Forschungszentrum Jülich). The event was organized by the SFB student speaker including 29 PhD Students, seven Master students and four postdoctoral researchers.

After a joint bus-ride from Marburg the program started with an official welcome and a first program overview by Maximilian Dreher, organizer and SFB student speaker. During the subsequent dinner, the participants started some first scientific discussions across departmental boundaries.

Poster session during the winter school. (Foto: Maximilian Dreher)

17 talks distributed over six sessions at three days were chaired by postdocs and experienced PhD students. The idea was to give introductory talks, such that everyone regardless of the own discipline and scientific experience could follow the topic to broaden the own horizon. Therefore, the talks were given an extra 10 min of discussion to answer as many open question as possible. All presenters did an excellent job of sharing their experience with the audience.

Highlights were talks by Carolin Kalff and Dominik Scharf, who presented a detailed lab day of an organic chemist or the talk by Willy Knorr, who gave insights into how to simulate transport characteristics of excitons.

Two poster session were held in the evenings after the dinner. Since only 12 poster per session were presented, everyone got the opportunity to have deep discussions at every poster. The overall atmosphere was very stimulating, such that the end of both sessions was late in the evening with many people still in discussion.

Besides the scientific program, the students got the opportunity to explore the beautiful landscape of Kleinwalsertal and enjoy the fresh air, while discussing the new insights they got during the week.