14. 11. 2024 13:10

Vladislav Sláma, Ph.D. » Towards new types of memory devices using molecular electronics

Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland

Molecular electronics is seen as a route to further miniaturize microelectronics and to extend Moor’s law beyond the limits of semiconductor-based platforms. The molecular electronics devices make use of the quantum nature of electrons and their control to facilitate specific functions. Our main focus here is on molecular electronics memories, where the specific resonance interaction between an electrode surface plasmon and the charge transfer state of an active molecule is used to influence the charge distribution by an external electric or magnetic field. In this project, we focus on investigating the nature of the coupling between active molecules and metallic electrodes. Understanding the interplay of the different interactions such as exciton-exciton, charge transfer and exciton-plasmon interactions and their dependence on the coupling between the active molecule and the surface, is a crucial step in developing novel molecular electronic devices. We aim to develop a computationally affordable approach correctly describing intrinsic quantum effects like mixing of the locally excited or charge transfer states with the surface plasmon resonance. This is essential for large-scale investigations of the new type of molecular devices.

I’ll present preliminary results on two promising groups of systems. The first group are functionalized small gold nanoclusters with attached chromophore with excitation energy close to the gold surface plasmon resonance. These systems are used mainly as a benchmark to develop the methodology for proper description of the interaction between the gold and the organic chromophore. Utilizing combined computational and experimental approaches, we investigate the nature of the mutual interactions between the gold nanocluster and the chromophore on relatively small (500 atoms) and well-defined systems. The second group are paracyclophane molecules deposited on a gold surface. These systems can serve as prototypes for future molecular memories. Paracyclophanes are molecules composed of two parallel units, one on top of the other. When paracyclophane is formed by two different units e.g. naphthalenediimide-Pyrene or naphthalenediimide-Azulene, we observe large charge transfer (CT) in the excited states close to the gold plasmon resonance with dipole moment perpendicular to the gold surface. Resonant coupling between the CT state and the gold plasmon resonance could then be utilized for future molecular memories.

Seminar on Condensed Matter Theory

Group of Theoretical Physics organizes a regular seminar on theory of condensed matter physics.

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every Thursdays at 13:00
in seminar room F 052
Ke Karlovu 5, 121 16 Praha 2.

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