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DY: Fachverband Dynamik und Statistische Physik

DY 43: Poster: Quantum Dynamics and Many-Body Systems

DY 43.21: Poster

Donnerstag, 30. März 2023, 13:00–16:00, P1

Enhancement and suppression of charge transport in organic semiconductors under strong light-matter coupling — •Sebastian Stumper and Junichi Okamoto — University of Freiburg, Institute of Physics

We study a model of an organic semiconductor coupled to a cavity with variable disorder and electronic filling factors as well as dissipative effects. It represents a fermionic generalization of the Dicke model such that charges can move between lattice sites.

Different mechanisms are explored to explain experimentally observed conductivity enhancements in the strong coupling regime. These are either based on an increase of the charge mobility or of the charge density. Mobilities and the generalized inverse participation ratio, which characterizes localization, are accessible from various two- and four-point correlators that we obtain by a Lanczos technique. In agreement with several previous studies, we find that excitons are indeed delocalized under strong light-matter coupling and show an enormously increased mobility. The same is not true for electrons and holes.

Charge densities are increased by excitation of electrons to the upper band through counter-rotating light-matter interaction terms. However, this is counteracted by the cavity-mediated formation of bound electron-hole states. We analyze the relative strengths of these processes under finite size scaling, and how the formation of bound states is affected by disorder and dephasing. In certain limits for an undoped system, the Dicke model is recovered.