Nonexponential Photoluminescence Dynamics in an Inhomogeneous Ensemble of Excitons in WSe2 Monolayers

• Published in: JETP letters Vol. 112; no. 10; pp. 607 - 614
• Main Authors: Akmaev, M. A., Kochiev, M. V., Duleba, A. I., Pugachev, M. V., Kuntsevich, A. Yu, Belykh, V. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2020; Springer Nature B.V
• Subjects: Atomic; Biological and Medical Physics; Biophysics; Dynamics; Excitation; Excitons; Molecular; Monolayers; Optical and Plasma Physics; Optics and Laser Physics; Particle and Nuclear Physics; Photoluminescence; Physics; Physics and Astronomy; Quantum Information Technology; Radiative recombination; Silicon dioxide; Silicon substrates; Solid State Physics; Spintronics; Transition metal compounds
• ISSN: 0021-3640; 1090-6487
• DOI: 10.1134/S0021364020220063

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 ∼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 the temperature and 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.