Dresden 2020 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: Optical properties
HL 33.2: Vortrag
Dienstag, 17. März 2020, 14:15–14:30, POT 112
Quantifying Exciton Effects in Graphene Nanoribbons — •Alexander Tries1,2,3, Paniz Soltani3, Mischa Bonn3, Hai I. Wang3, and Mathias Kläui1,2 — 1Institute of Physics, Johannes Gutenberg-University Mainz — 2Graduate School of Excellence Materials Science in Mainz — 3Max Planck Institute for Polymer Research, Mainz
Owing to their massless nature, charge carriers in graphene can possess extremely high electron mobility. Yet, its gapless, semi-metallic nature can present a drawback for applications. Recent advances in bottom-up synthesis allows for the atomic control of graphene nanoribbons (GNRs)with well-defined bandgap and optical properties. [1,2]
In these structures, carrier confinement in the lateral dimension induces a bandgap corresponding to visible wavelengths. Owing to the strongly reduced charge screening effect in these atomically flat nanoribbons, strong exciton effects are expected and exciton binding energies in excess of ~1 eV have been predicted. [3] We will present recent optical ultrafast conductivity studies on atomically precise GNRs using THz spectroscopy, which demonstrates and confirms the strong exciton and charged exciton effects [4]. Time-dependent photoconductivity measurements shed light on the sub- picosecond dynamics of the different quasi-particles.
[1] J. Cai et al., Nature 2010, 466, 470 [2] Z. Chen et al., J. Am.Chem. Soc. 2017, 139, 3635. [3] L. Yang et al., Nano Lett. 2007, 7 (10), 3112 [4] A. Tries et al.,ArXiv:1911.04431