Séminaire présenté par Dr. Salambô Dago

Orateur : Dr. Salambô Dago

Vienna Center for Quantum Science and Technology (VCQ) University of Vienna)

Résumé : Feedback control provides a versatile tool for manipulating nanoscale systems dominated by thermal or quantum fluctuations. We present two experimental applications of feedback to explore non equilibrium physics. First, we demonstrate how a feedback loop can create a virtual double potential for an underdamped micromechanical oscillator, enabling a 1-bit memory platform to perform fast logical operations and investigate the energetic cost of information processing [1-5].
Second, we introduce FLIP (Feedback Stabilization on an Inverted Potential), a novel feedback scheme combining Kalman filtering with optical trapping to achieve quantum control [6] and ground-state cooling of levitated nanospheres. This approach allows stable levitation in a double-well configuration while mitigating absorption, opening new routes for optical manipulation at the quantum limit [7].

[1] S. Dago, J. Pereda, S. Ciliberto, and L. Bellon,. JSTAT, 2022(5):053209, (2022).
[2] S. Dago, J. Pereda, N. Barros, S. Ciliberto, and L. Bellon, Phys. Rev. Lett., 126:170601 (2021).
[3] S. Dago, and L. Bellon, Phys. Rev. Lett., 128, 070604 (2022)
[4] S. Dago, L. Bellon, Phys. Rev. E 108, L022101 (2023)
[5] S. Dago, S. Ciliberto and L. Bellon, PNAS Vol.120, No 39
[6] L. Magrini, P. Rosenzweig, C. Bach, A. Deutschmann-Olek, S. G. Hofer, S. Hong, N. Kiesel, A. Kugi
Nature 595, 373 (2021).
[7] S. Dago, J. Rieser, M. Ciampini, V. Mlynar, M. Aspelmeyer, A. Deutschmann-Olek et N. Kiesel Optics
Express 32, 45133-45141 (2024

Contact : Cyriaque Genet
genet@unistra.fr / 03 68 85 51 96

Séminaire DMO présenté par Prof. PACHAIYAPPAN RAJAMALLI

Orateur : Prof Pachaiyappan RAJAMALLI

Résumé : Thermally activated delayed fluorescence (TADF) emitters have garnered much attention due to 100% exciton utilization and toxic metal-free design. However, most of the TADF emitters experience a concentration-quenching effect due to which emitting layers are dispersed into the host matrix. There is an urgent need to develop emitters that give the same performance and emission wavelength irrespective of the concentration of emitters. Herein, two TADF emitters (2BPy-pTC and 2BPy-oTC) are designed and synthesized. For both emitters, the nature and energetics of the lowest excited singlet and triplet together with the extent of through-bond exciton transfer (TBET) and through-space exciton transfer (TSET) are unveiled using reliable quantum-chemical calculations. While 2BPy-pTC exhibits pre-dominantly TBET, a greater extent of TSET is found in 2BPy-oTC. 2BPy-pTC displays blue color with emission maxima at 469 nm while 2BPy-oTC exhibits green color with emission maxima at 509 nm in toluene. Both emitters show a low singlet-triplet energy gap (ΔEST) of 0.20 eV for 2BPy-pTC and 0.01 eV for 2BPy-oTC and a delayed lifetime of 147.4 μs for 2BPy-pTC and 7.4 μs for 2BPy-oTC. 2BPy-pTC shows EQEmax of 12% with an Electroluminescence (EL) peak at 467 nm while 2BPy-oTC shows EQEmax of 24% with EL maxima of 500 nm. In the case of 2BPy-pTC, upon increasing the concentration of the dopant from 5 wt% to 100 wt%, the EL peak experiences a bathochromic shift from 467 to 495 nm and EQEmax drops from 12% to 5.5%. On the other hand, 2BPy-oTC maintains EQEmax of ~24% and EL maxima of 500 nm while increasing the concentration of dopant from 5 wt% to 100 wt%. Hence, 2BPy-oTC acts as a universal dopant for both doped and non-doped OLEDs through which the tedious co-deposition process can be avoided.

References

[1] Chem. Commun., 2024,60, 9234.

[2] J. Mater. Chem. C, 2023, 11, 16368.

[4] ACS Appl. Electron. Mater, 2023, 5, 4959. [5] Adv. Optical Mater.2024, 2402820.

Séminaire DSI présenté par Gracie Chaney

Gracie Chaney (Sorbonne Université, Laboratoire de Chimie Theorique PARIS)

résumé : Although ab initio molecular dynamics (AIMD) can predict the chemical reactions in materials with quantum accuracy, it suffers from computational inefficiency that constrains simulations in size (<1000 atoms) and time (<100 ps). Machine learned interatomic potentials (MLIPs) bridge the gap between quantum accuracy and classical efficiency by learning the potential energy surface of the system from the AIMD data and using it as the force field in classical molecular dynamics (CMD) simulations. In this presentation, I will feature two very different systems for which I have used MLIPS. The first is the interface of a solid-state battery consisting of a Li-metal anode and an argyrodyte Li6PS5Cl solid-state electrolyte. By using a moment-tensor potential scheme we were able to generate an MLIP that accurately predicted the short- and long-term growth of the solid-electrolyte interphase region initiated by reduction of the electrolyte by the anodic Li [2]. The second system consists of a dense liquid of NH3/H2O/CH4 subjected to extreme temperatures (3000 K) and pressures (22-69GPa). In this case, we used an equivariant neural network potential [3] trained on an even distribution of NH3/H2O/CH4 structures of various NH3 amounts (4, 8, and 12). Both the AIMD and MLIP+MD simulations showed that increasing pressure at high temperature induces water ionization and begins a process involving the formation of transient CH5+ molecules and highly reactive carbocations that drive hydrocarbon chain growth toward nanodiamonds. Such results could be useful for understanding the dynamics within icy giant planets, such as Uranus and Neptune.

[1] Ivan S Novikov et al. 2021 Mach. Learn.: Sci. Technol. 2, 025002

[2] Gracie Chaney et al. 2024 ACS Appl. Mater. Interfaces 16, 19, 24624–24630

[3] Musaelian, A., Batzner, S., Johansson, A. et al. (2023) Nat Commun 14, 579

Pour tout contact : Hervé Bulou (0388107095 – herve.bulou@ipcms.unistra.fr) et Christine Goyhenex (0388107097 – christine.goyhenex@ipcms.unistra.fr)

Séminaire Joël Bellessa

Joël Bellessa (Institut Lumière Matière, CNRS-Université Lyon 1)

La proximité de nanostructures ou de films métalliques avec des semi-conducteurs affecte considérablement leurs propriétés, en particulier optiques. Nous décrirons, dans un premier temps, le couplage fort lumière-matière entre des semi-conducteurs organiques (molécules de type J-agrégat) et un mode de plasmon de surface. Nous discuterons en particulier des effets collectifs entre différentes molécules, induits par l’hybridation lumière-matière. En structurant le matériau à l’échelle de l’extension des modes cohérents, nous montrerons qu’il est possible de créer un type original de métasurface active polaritonique, ainsi qu’un transfert d’énergie efficace. Dans un deuxième temps, nous aborderons des structures comprenant des métaux et des semi-conducteurs inorganiques (arséniure de gallium). Les potentialités applicatives de ces structures pour la réalisation de lasers de surface seront décrites.

Séminaire du Prof. Ryo Nakayama

Orateur : Prof Ryo Nakayama, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan

Résumé :

Thin-film model systems offer a powerful platform for studying interfacial phenomena in solid-state lithium batteries and complex hydride electrolytes.  At the Li₃PO₄/LiCo₀.₅Mn₁.₅O₄ interface in a thin-film lithium batteries, the resistance increases above 5 V vs Li/Li+ due to interfacial layer formation but relaxes over time, indicating reversible behavior.  Epitaxial NaBH₄ thin films have been successfully fabricated via infrared pulsed-laser deposition, allowing control over growth orientation which is useful for interface study. These findings highlight the effectiveness of thin films in elucidating interface properties and advancing solid-state energy materials.

Contact: Pierre RABU : pierre.rabu@ipcms.unistra.fr

Seminaire du Pr. Chihaya Adachi, CNRS fellow-ambassador

Orateur : Prof. Chihaya Adachi

Chihaya Adachi is a professor at Kyushu University in Japan and director of the Photonics and Organic Electronics Research Centre (OPERA). His activities focus on the chemistry, physics and implementation of organic semiconductor materials for applications in photonics and organic electronics. In particular, it is behind the development of the third generation of light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) organic materials. Cultivating close links with industry, Chihaya Adachi has co-founded two start-ups: Kyulux, in 2014, for the development and commercialisation of new materials for the OLED market; and Koala Tech, in 2019, for the development of purely organic laser materials and devices. Finally, he has developed numerous international collaborations, particularly with France. In 2023, the CNRS launched the IRP LUX-ERIT, which brings together the OPERA laboratory and four French laboratories, including the Institut de Physique et de Chimie des Matériaux de Strasbourg (IPCMS), the Institut Lavoisier de Versailles (ILV), the Laboratoire de Physique des Lasers (LPL) and the Institut Parisien de Chimie Moléculaire (IPCM), which is currently coordinating the project on the French side.

To meet C. Adachi, please contact: stephane.mery@ipcms.unistra.fr

Séminaire DMO présenté par : OLivier MAURY

Olivier Maury (ENS, https://perso.ens-lyon.fr/olivier.maury/)

Old polymethine dyes, discovered in the middle of the XIXth century for photography application, continue to hold a real fascination in the scientific community owing to their unique spectroscopic properties. In the last decade, these dyes found a renewal of interest for near-infrared (NIR) applications in biological imaging or for the design of advanced photonic materials (laser dyes, nonlinear optics…). Generally speaking, polymethine dyes are charged compounds where the positive (resp. negative) charge is delocalized between two electron-donating (resp. withdrawing) groups via an odd number of sp2 carbon atoms. In spite of their wide range of use, the complete rationalization of their very particular photophysical properties remains a matter of debate from both experimental and theoretical points of view.