Negative effective excitonic diffusion in monolayer transition metal dichalcogenides
Journal article, 2020

While exciton relaxation in monolayers of transition metal dichalcogenides (TMDs) has been intensively studied, spatial exciton diffusion has received only a little attention-in spite of being a key process for optoelectronics and having already shown interesting unconventional behaviours (e.g. spatial halos). Here, we study the spatiotemporal dynamics in TMD monolayers and track optically excited excitons in time, momentum, and space. In particular, we investigate the temperature-dependent exciton diffusion including the remarkable exciton landscape constituted by bright and dark states. Based on a fully quantum mechanical approach, we show at low temperatures an unexpected negative effective diffusion characterized by a shrinking of the spatial exciton distributions. This phenomenon can be traced back to the existence of dark exciton states in TMD monolayers and is a result of an interplay between spatial exciton diffusion and intervalley exciton-phonon scattering.

Author

Roberto Rosati

Chalmers, Physics, Condensed Matter and Materials Theory

Raul Perea Causin

Chalmers, Physics, Condensed Matter and Materials Theory

Samuel Brem

Chalmers, Physics, Condensed Matter and Materials Theory

Ermin Malic

Chalmers, Physics, Condensed Matter and Materials Theory

2D-Tech

Nanoscale

2040-3364 (ISSN)

Vol. 12 1 356-363

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics

DOI

10.1039/c9nr07056g

PubMed

31825433

More information

Latest update

9/7/2020 7