Impact of temperature on the brightening of neutral and charged dark excitons in WSe 2 monolayer
Year: 2024
Type: article
Abstract: Optically dark states play an important role in the electronic and optical properties of monolayers (MLs) of semiconducting transition metal dichalcogenides. The effect of temperature on the in‐plane‐field activation of the neutral and charged dark excitons is investigated in a WSe 2 ML encapsulated in hexagonal BN flakes. The brightening rates of the neutral dark ( X D ) and grey ( X G ) excitons and the negative dark trion ( T D ) differ substantially at particular temperature. More importantly, they weaken considerably by about 3–4 orders of magnitude with temperature increased from 4.2 K to 100 K. The quenching of the dark‐related emissions is accompanied by the two‐order‐of‐magnitude increase in the emissions of their neutral bright counterparts, i . e . neutral bright exciton ( X B ) and spin‐singlet ( T S ) and spin‐triplet ( T T ) negative trions, due to the thermal activations of dark states. Furthermore, the energy splittings between the dark X D and T D complexes and the corresponding bright X B , T S , and T T ones vary with temperature rises from 4.2 K to 100 K. This is explained in terms of the different exciton–phonon coupling for the bright and dark excitons stemming from their distinct symmetry properties.
Source: Nanophotonics
Institutions: University of Warsaw, Centre National de la Recherche Scientifique, National University of Singapore, Laboratoire National des Champs Magnétiques Intenses, Institute for Functional Intelligent Materials, Université Grenoble Alpes, National Institute for Materials Science, Warsaw University of Technology
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,706
OpenAlex ID: W4404561983