Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides

Samuel Brem; August Ekman; Dominik Christiansen; Florian Katsch; Malte Selig; Cedric Robert; Xavier Marie; Bernhard Urbaszek; Andreas Knorr; Ermin Malic

doi:10.1021/acs.nanolett.0c00633

arXiv · 1904.04711

Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides

Samuel Brem·August Ekman·Dominik Christiansen·Florian Katsch·Malte Selig·Cedric Robert·Xavier Marie·Bernhard Urbaszek·Andreas Knorr·Ermin Malic

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Abstract

The photoluminescence (PL) spectrum of transition metal dichalcogenides (TMDs) shows a multitude of emission peaks below the bright exciton line and not all of them have been explained yet. Here, we study the emission traces of phonon-assisted recombinations of momentum-dark excitons. To this end, we develop a microscopic theory describing simultaneous exciton, phonon and photon interaction and including consistent many-particle dephasing. We explain the drastically different PL below the bright exciton in tungsten- and molybdenum-based materials as result of different configurations of bright and dark states. In good agreement with experiments, we show that WSe$_2$ exhibits clearly visible low-temperature PL signals stemming from the phonon-assisted recombination of momentum-dark excitons.

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Samuel Brem, August Ekman, Dominik Christiansen, Florian Katsch, Malte Selig, Cedric Robert, Xavier Marie, Bernhard Urbaszek, Andreas Knorr, Ermin Malic. 2019-04-09. Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of Transition Metal Dichalcogenides. https://doi.org/10.1021/acs.nanolett.0c00633

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