Nonexponential photoluminescence dynamics in an inhomogeneous ensemble of excitons in WSe\(_2\) monolayers

• Published in: arXiv.org
• Main Authors: Akmaev, M A, Kochiev, M V, Duleba, A I, Pugachev, M V, A Yu Kuntsevich, Belykh, V V
• Format: Paper
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 24.12.2020
• Subjects: Dynamics; Excitation; Excitons; Monolayers; Photoluminescence; Radiative recombination; Silicon substrates; Transition metal compounds
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2012.13181

The spectral and spatiotemporal dynamics of photoluminescence in monolayers of transition metal dichalcogenide WSe\(_2\) obtained by mechanical exfoliation on a Si/SiO\(_2\) substrate is studied over a wide range of temperatures and excitation powers. It is shown that the dynamics is nonexponential and, for times \(t\) exceeding \(\sim\)50 ps after the excitation pulse, is described by a dependence of the form \(1/(t+t_0)\). Photoluminescence decay is accelerated with a decrease in temperature, as well as with a decrease in the energy of emitting states. It is shown that the observed dynamics cannot be described by a bimolecular recombination process, such as exciton--exciton annihilation. A model that describes the nonexponential photoluminescence dynamics by taking into account the spread of radiative recombination times of localized exciton states in a random potential gives good agreement with experimental data.