Dark and bright exciton formation, thermalization, and photoluminescence in monolayer transition metal dichalcogenides
Journal article, 2018

The remarkably strong Coulomb interaction in atomically thin transition metal dichalcogenides (TMDs) results in an extraordinarily rich many-particle physics including the formation of tightly bound excitons. Besides optically accessible bright excitonic states, these materials also exhibit a variety of dark excitons. Since they can even lie below the bright states, they have a strong influence on the exciton dynamics, lifetimes, and photoluminescence. While very recently, the presence of dark excitonic states has been experimentally demonstrated, the origin of these states, their formation, and dynamics have not been revealed yet. Here, we present a microscopic study shedding light on time- and energy-resolved formation and thermalization of bright and dark intra- and intervalley excitons as well as their impact on the photoluminescence in different TMD materials. We demonstrate that intervalley dark excitons, so far widely overlooked in current literature, play a crucial role in tungsten-based TMDs giving rise to an enhanced photoluminescence and reduced exciton lifetimes at elevated temperatures.

quantum yield

transition metal dichalcogenides

photoluminescence

exciton dynamics

excitons

Author

Malte Selig

Technische Universität Berlin

Chalmers, Physics, Condensed Matter Theory

Gunnar Berghäuser

Chalmers, Physics, Condensed Matter Theory

Marten Richter

Technische Universität Berlin

R. Bratschitsch

University of Münster

A. Knorr

Technische Universität Berlin

Ermin Malic

Chalmers, Physics, Condensed Matter Theory

2D Materials

2053-1583 (eISSN)

Vol. 5 3 035017

Graphene Core1. Graphene-based disruptive technologies (Graphene Flagship)

European Commission (Horizon 2020), 2016-04-01 -- 2018-03-31.

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics

DOI

10.1088/2053-1583/aabea3

More information

Latest update

8/31/2018