Upcoming Talks and Events:

André-Jean Attias

Affiliation: CNRS / SorbonneUniversité / Yonsei University
Date: September 17, 2020; 15:00 – 16:00

The seminar will be held online, if you want to join the meeting, please, write to us at info@qns.science.

Electronic Decoupling Strategies for Emitting Graphene-BasedHybrid Platforms: Surface-Confined Supramolecular Self-Assembly as Tool

TElectronicdecoupling of molecular chromophores from graphene to preserve their electronic and optical properties with the objective to elaborate light-responsive hybrid systems for new electronic and optoelectronic nanodevices remains largely unexplored.

In this context, the supramolecular self-assembly of organic building blocks on graphene is an original bottom-up approach towards novel materials displaying unusual properties.[1] Hence, the possible fine-tuning of inter-constituents distances and orientations offered by the design of the building blocks makes the self-assembly approach very appealing for adjusting graphene photonic properties.

Here, we present two examples of electronic decoupling strategies we have recently developed.

In the first one, the quenching of the fluorescence of the adsorbed dye by the adjacent graphene is hindered at the molecular scale. In this spacer-based approach, a specifically designed dual-functionalized building block was self-assembled on graphene leading to the first light-emitting graphene-based hybrid 2D system [2].

The second example is based on surface-confined host-guest chemistry used to trap afunctional 3D building blocks into a large 2D nanoporous template on graphene [3]. This noncovalent graphene functionalization approach allows the immobilization, in a well-defined 2D nanoporous network, of an afunctional 3D complex that projects a dye-based ligand away from the surface and aligned along the normal direction. Thanks to this strategy of decoupling from the graphene as well as the orientation and intermolecular distance control, the platform emits light with the same characteristics as in dilute solution [4].

This decoupling method could open perspectives in the field of electrically induced luminescence at the single-molecule level through STM tip-induced electrical fields.

[1] L. Sosa-Vargas, E. Kim, A. J.Attias, Materials. Horizons, 4, 570(2017)
[2] S. LeLiepvre, P. Du, D. Kreher, F. Mathevet, A. J. Attias, C. Fiorini-Debuisschert,L. Douillard, F. Charra, ACS Photonics,3, 2291−2296 (2016)
[3] R. Brisse, D. Guianvarc’h, C. Mansuy, S. Sagan, D. Kreher, L. Sosa-Vargas, L. Hamitouche,V. Humblot, I. Arfaoui, V. Labet, C. Paris, C. Petit, A. J. Attias, Chem. Commun., 54, 10068 (2018)
[4] B. Kim, E.Kim, I. Arfaoui, C. Paris, C. Petit, A. J. Attias, Materials Horizons, DOI:10.1039/D0MH00950D (2020)

Je-Geun Park

Affiliation: Department of Physics and Astronomy, Seoul National University
Date: August 19, 2020; 16:00 – 17:00
Location: Saturn Seminar Room

Current status and perspective of magnetic van der Waals materials research

The discovery of graphene in 2004 took the scientific community by surprise and virtually transformed the research landscape by creating a then-new field of 2d materials. However, despite the unique properties of many van der Waals materials since discovered, it has certain limitations in terms of exploring novel and new physical properties. Magnetism is a case in point. Until a couple of groups and I started to work on the much-neglected magnetic van der Waals materials, virtually nothing was known about it. However, with a series of publications, including those from my group, this field of magnetic van der Waals materials has become a fast emerging field in materials science. In this presentation, I would like to take you through the intellectual journey I made since 2010 and eventually discovering a novel quantum spin-entangled exciton NiPS3 more recently. I will end my talk by giving a personal view of the prospect for future research.

[1] Je-Geun Park, J.Phys. Condens. Matter 28, 301001 (2016)
[2] Cheng-Tai Kuo, et al., Scientific Reports 6, 20904 (2016)
[3] Jae-Ung Lee, et al., Nano Lett. 16, 7433 (2016)
[4] So Yeun Kim, et al., Phys. Rev. Lett. 120, 136402 (2018)
[5] K. S. Burch, D.Mandrus, and Je-Geun Park, Nature 563, 47 (2018)
[6] Kangwon Kim, et al., Nature Comm. 10, 345 (2019)
[7] H Chu, et al., Phys. Rev. Lett. 124, 027601 (2020)
[8] S. Kang, et al., Nature 583, 785 (2020)