Dark exciton anti-funneling in atomically thin semiconductors
Artikel i vetenskaplig tidskrift, 2021

Strain engineering can manipulate the propagation of excitons in atomically thin transition metal dichalcogenides. Here, the authors observe an anti-funnelling behavior, i.e., the exciton photoluminescence moves away from high-strain regions, and attribute it to the dominating role of propagating dark excitons. Transport of charge carriers is at the heart of current nanoelectronics. In conventional materials, electronic transport can be controlled by applying electric fields. Atomically thin semiconductors, however, are governed by excitons, which are neutral electron-hole pairs and as such cannot be controlled by electrical fields. Recently, strain engineering has been introduced to manipulate exciton propagation. Strain-induced energy gradients give rise to exciton funneling up to a micrometer range. Here, we combine spatiotemporal photoluminescence measurements with microscopic theory to track the way of excitons in time, space and energy. We find that excitons surprisingly move away from high-strain regions. This anti-funneling behavior can be ascribed to dark excitons which possess an opposite strain-induced energy variation compared to bright excitons. Our findings open new possibilities to control transport in exciton-dominated materials. Overall, our work represents a major advance in understanding exciton transport that is crucial for technological applications of atomically thin materials.


Roberto Rosati

Philipps-Universität Marburg

Robert Schmidt

Universität Münster

Samuel Brem

Philipps-Universität Marburg

Raul Perea Causin

Chalmers, Fysik, Kondenserad materie- och materialteori

Iris Niehues

Universität Münster

Johannes Kern

Universität Münster

Johann A. Preuss

Universität Münster

Robert Schneider

Universität Münster

Steffen Michaelis de Vasconcellos

Universität Münster

Rudolf Bratschitsch

Universität Münster

Ermin Malic

Philipps-Universität Marburg

Chalmers, Fysik, Kondenserad materie- och materialteori

Nature Communications

2041-1723 (ISSN)

Vol. 12 1 7221

Graphene Core Project 3 (Graphene Flagship)

Europeiska kommissionen (EU) (EC/H2020/881603), 2020-04-01 -- 2023-03-31.


Atom- och molekylfysik och optik

Annan materialteknik

Den kondenserade materiens fysik





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