Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Poster 1

HL 25.53: Poster

Mittwoch, 7. September 2022, 18:00–20:00, P2

Damping and detecting vibrational modes in organic semiconductors with tunable graphene cavities — •Lukas Renn and Thomas Weitz — I. Physical Institute, Georg-August-University, Friedrich-Hund-Platz 1, 37077, Göttingen

The true nature of charge transport in organic semiconductors (OSC) is still not fully understood. A novel picture to describe the charge transport is the so-called transient localization, where the charge transport is intrinsically limited by inter- and intramolecular vibrations, which are a direct consequence of the weak van der Waals interactions in OSCs. Recently it was discovered that the mobility in OSCs is mainly hampered by single low-frequency sliding modes, which in some molecules contribute more than 80% of the total thermal disorder. (1) The aim of this work is to first detect the lattice vibrations in OSCs and subsequently manipulate them using 2D cavities. To this end, we deposit monolayer thin, highly crystalline OSC films (PDI1MPCN2) from solution onto graphene flakes, which should result in quenching of a broad spectral range of IR-active vibrational modes in the OSC. First measurements show that we are able to detect the vibrational modes via Raman and a SNOM-based Nano-FTIR measurement setup. One step further, we want to tune the plasmon frequencies of the graphene cavities via lithography-patterning and thereby selectively couple to molecular vibrations in this frequency range and measure their relative impact on the charge carrier mobility. (1) Schweicher et al., Adv. Mat. 1902407 (2019)