Structural effects on exciton phenomena in transition metal dichalcogenides from many-body perturbation theory
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Structural effects on exciton phenomena in transition metal dichalcogenides from many-body perturbation theory
Sivan Refaely-Abramson
Senior Scientist
Department of Materials and Interfaces
Weizmann Institute of Science, Israel
New developments in the theory of excited-state phenomena can lead to better understanding of the involved nanoscale mechanisms and to predictions of new materials hosting such phenomena. In this talk, I will present recent studies using many-body perturbation theory within the GW-BSE approach to model and understand such mechanisms in functional materials. I will discuss the effect of point defects on excited-state properties and selection rules in monolayer transition metal dichalcogenides (TMDs). These impurities can give rise to localized states, introduce strongly-bound excitons below the absorption edge, and reduce the valley-selective circular dichroism, suggesting a novel pathway to tune spin-valley polarization and other optical properties through defect engineering. I will further discuss quasiparticle and exciton properties in TMD heterostructures, where interlayer interactions lead to subtleties in the electron-hole coupling and determine the excitonic nature across the junction. I will present a new approach to exciton-exciton interactions in solids, with a recent application to singlet fission in molecular crystals, as a path to explore exciton transport in the examined crystals.