Unveiling the defect-induced charge and exciton properties of van der Waals interfaces through first-principles
Daniel Hernangómez-Pérez a
a Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, 7610001 Rehovot, Israel
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS23 & Sustainable Technology Forum València (STECH23) (MATSUS23)
#QMat - Materials for Quantum Technology
VALÈNCIA, Spain, 2023 March 6th - 10th
Organizers: José J. Baldoví, Dmitry Baranov and Jannika Lauth
Invited Speaker, Daniel Hernangómez-Pérez, presentation 373
DOI: https://doi.org/10.29363/nanoge.matsus.2023.373
Publication date: 22nd December 2022

In recent years, the study of charge transfer and excitonic properties of van der Waals matter has been a rapidly growing area of research due to their importance for ultrathin optoelectronic, photovoltaic and photocatalytic components. In such applications, quasi-particles and excitons, often act as carriers in charge, spin and energy transfer processes. These transport processes can be significantly impacted by structural complexity, reduced dimensionality, interface composition or the presence of impurities and adatoms. In this talk, I will address some of these complexities from first principles, focusing on transition-metal dichalcogenides (TMDC) and TMDC-graphene interfaces. I will discuss the role of state localization due to atomic-size defects on the optical and magnetic properties [1, 2]. Using many-body perturbation theory within the GW and Bethe-Salpeter equation approach, I will show how the excitonic picture associated with the presence of defects, which result in a reduced valley and spin selectivity due to hybridized electron-hole transitions, can lead to structurally controllable exciton magnetic response. Subsequently, I will delve into the role of symmetries in charge transfer and excitonic properties on TMDC-graphene heterobilayers containing monoatomic chalcogen vacancies [3]. I will analyze the impact of the subgap defect-based features on the microscopic dynamics and absorption features, including the interplay between the spatial and the spin degrees of freedom through the spin-orbit interaction. Finally, I will show how defects become a slow coherent transport channel for interlayer charge transfer while simultaneously stronly altering the exciton properties of the TMDC-graphene interface due to a combination of folding, screening and mixing of the optical transitions.


[1] E. Mitterreiter, B. Schuler, A. Micevic, D. Hernangómez-Pérez, et al. Nat. Comm. 12, 3822 (2021).

[2] T. Amit, D. Hernangómez-Pérez, G. Cohen, D. Y. Qiu, and S. Refaely-Abramson, Phys. Rev. B 106, L161407 (2022).

[3] D. Hernangómez-Pérez, A. Donarini, and S. Refaely-Abramson (Phys. Rev. B, accepted, Editor's Suggestion).

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