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Exciton Radiative Lifetimes in Two-Dimensional Transition Metal Dichalcogenides

Palummo, Maurizia and Bernardi, Marco and Grossman, Jeffrey C. (2015) Exciton Radiative Lifetimes in Two-Dimensional Transition Metal Dichalcogenides. Nano Letters, 15 (5). pp. 2794-2800. ISSN 1530-6984. doi:10.1021/nl503799t.

[img] PDF (GW bandstructures of MoS2, WS2, MoSe2, and WSe2. Detailed derivation of eqs 1−3.) - Supplemental Material
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Light emission in two-dimensional (2D) transition metal dichalcogenides (TMDs) changes significantly with the number of layers and stacking sequence. While the electronic structure and optical absorption are well understood in 2D-TMDs, much less is known about exciton dynamics and radiative recombination. Here, we show first-principles calculations of intrinsic exciton radiative lifetimes at low temperature (4 K) and room temperature (300 K) in TMD monolayers with the chemical formula MX_2 (X = Mo, W, and X = S, Se), as well as in bilayer and bulk MoS2 and in two MX_2 heterobilayers. Our results elucidate the time scale and microscopic origin of light emission in TMDs. We find radiative lifetimes of a few picoseconds at low temperature and a few nanoseconds at room temperature in the monolayers and slower radiative recombination in bulk and bilayer than in monolayer MoS_2. The MoS_2/WS_2 and MoSe_2/WSe_2 heterobilayers exhibit very long-lived (∼20–30 ns at room temperature) interlayer excitons constituted by electrons localized on the Mo-based and holes on the W-based monolayer. The wide radiative lifetime tunability, together with the ability shown here to predict radiative lifetimes from computations, hold unique potential to manipulate excitons in TMDs and their heterostructures for application in optoelectronics and solar energy conversion.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Palummo, Maurizia0000-0002-3097-8523
Bernardi, Marco0000-0001-7289-9666
Grossman, Jeffrey C.0000-0003-1281-2359
Additional Information:© 2015 American Chemical Society. Received: October 2, 2014; Revised: February 18, 2015; Published: March 23, 2015. M.P. thanks M. Fanfoni for discussion and D. Varsano and D. Sangalli for help with code implementation. M.B. and J.C.G. thank NERSC and XSEDE for computational resources. M.P. thanks Cineca, within the ISCRA-C initiative, for computational resources. This work was partially supported by the Lockheed Martin Corporation. M.P. and M.B. contributed equally to this work. The authors declare no competing financial interest.
Funding AgencyGrant Number
Lockheed Martin CorporationUNSPECIFIED
Subject Keywords:Monolayer materials; transition metal dichalcogenides; luminescence; radiative lifetime; excitons; optoelectronics
Issue or Number:5
Record Number:CaltechAUTHORS:20150923-143833542
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Official Citation:Exciton Radiative Lifetimes in Two-Dimensional Transition Metal Dichalcogenides Maurizia Palummo, Marco Bernardi, and Jeffrey C. Grossman Nano Letters 2015 15 (5), 2794-2800 DOI: 10.1021/nl503799t
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60450
Deposited By: George Porter
Deposited On:23 Sep 2015 23:01
Last Modified:10 Nov 2021 22:34

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