Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 105: 2D Materials VII: Heterostructures (joint session O/TT)
O 105.4: Vortrag
Freitag, 22. März 2024, 11:15–11:30, MA 005
Complexity of excitons at the TMD-Graphene interface — •Amir Kleiner, Daniel Hernangómez Pérez, and Sivan Refaely-Abramson — Weizmann Institute of Science, Rehovot, Israel
The complex optical characteristics of heterostructures composed of layered 2D materials are of great importance and interest. Specifically, the interaction between light and matter at the interface of layered transition metal dichalcogenides (TMDs) and graphene draw significant interest, facilitating the understanding of related energy-transfer mechanisms and their structural roots. We use state-of-the-art first principles calculations to study the dependence of the excitonic composition and absorption properties of the representative WS2 - Graphene heterostructures on the structural details of these structures. Examining the cases of 0∘ and 30∘ degrees of interlayer twist angle, we find that the induced Brillouin zone mismatch, and concomitantly the energy level alignment between the graphene Dirac cone and the TMD bands, dictate the excitonic properties resulting in significant variation between the two systems. In particular, these set the charge-separation of nature of low-energy interlayer excitons and the state hybridization of optically active intralayer excitonic peaks. We use our results to numerically quantify the graphene-induced homogeneous broadening as a function of heterostructure alignment. Our findings provide guidelines for optical excitations based on the composition of the heterostructure, indicating a direct connection between the stacking of the layers, the separation of charges within the excitons, and the broadening of optical features.
Keywords: Heterostructures; TMD; graphene; exciton; ab-initio