Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 97: Ultrafast Electron Dynamics at Surfaces and Interfaces III

O 97.5: Vortrag

Freitag, 5. April 2019, 11:30–11:45, H16

Ultrafast charge carrier dynamics at the interface F4TCNQ:H-Si(111) from real-time TDDFT — •Matheus Jacobs, Jannis Krumland, Ana M. Valencia, and Caterina Cocchi — Institut fur Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Germany

The electronic structure of inorganic surfaces can be effectively modified by the adsorption of molecular acceptors acting as dopants. As a result, their interaction with light can give rise to charge-transfer excitations at the interface, making the systems potentially appealing for optoelectronic applications. To this end, gaining insight and control on the dynamics of the photo-excited charge-carrier population is an essential task. Here, we consider the interface formed by the strong electron acceptor F4TCNQ adsorbed on the hydrogenated Si(111) surface, which was recently characterized both theoretically and experimentally [1]. The linear absorption spectrum of this system exhibits two maxima in the visible region corresponding to transitions between electronic states hybridized across the interface. In the framework of real-time time dependent density functional theory, as implemented in the octopus code [2], we investigate the charge-carries dynamics induced by a laser pulse in resonance with each excitation and analyze the time evolution of the photoexcited electronic population. Our results offer insight into the earliest stage formation of optical excitations at hybrid interfaces.

[1] H. Wang, et al. arXiv:1811.00037 (2018).

[2] A. Castro, et al. Phys. Stat. Sol. B 243, 2465 (2006)