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Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides

Chen, Hsiao-Yi and Palummo, Maurizia and Sangalli, Davide and Bernardi, Marco (2018) Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides. Nano Letters, 18 (6). pp. 3839-3843. ISSN 1530-6984. doi:10.1021/acs.nanolett.8b01114.

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Monolayer transition metal dichalcogenides (TMDCs) are direct gap semiconductors with a unique potential for use in ultrathin light emitters. However, their photoluminescence (PL) is not completely understood. We develop an approach to compute the radiative recombination rate in monolayer TMDCs as a function of photon emission direction and polarization. Using exciton wavefunctions and energies obtained with the ab initio Bethe−Salpeter equation, we obtain polar plots of the PL for different scenarios. Our results can explain the PL anisotropy and polarization dependence measured in recent experiments and predict that light is emitted with a peak intensity normal to the exciton dipole in monolayer TMDCs. We show that excitons emit light anisotropically upon recombination when they are in any quantum superposition state of the K and K′ inequivalent valleys. When averaged over the emission angle and exciton momentum, our new treatment recovers the temperature-dependent radiative lifetimes that we previously derived. Our work demonstrates a generally applicable first-principles approach to studying anisotropic light emission in two-dimensional materials.

Item Type:Article
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URLURL TypeDescription Information Paper
Chen, Hsiao-Yi0000-0003-1962-5767
Palummo, Maurizia0000-0002-3097-8523
Sangalli, Davide0000-0002-4268-9454
Bernardi, Marco0000-0001-7289-9666
Additional Information:© 2018 American Chemical Society. Received: March 20, 2018; Revised: May 5, 2018; Published: May 8, 2018. H.-Y.C thanks the Taiwan Ministry of Education for fellowship support. M.B. acknowledges support by the National Science Foundation under grant no. ACI-1642443 and partial support from the Space Solar Program Initiative at the California Institute of Technology. M.P. acknowledges PRACE for computational resources on Marconi at CINECA (Grant No. Pra16_4181), and the Tor Vergata University for financial support through the Mission Sustainability Project 2DUTOPI. D.S. acknowledges funding from the European Union project MaX Materials design at the eXascale H2020-EINFRA-2015-1, grant agreement no. 676598, and Nanoscience Foundries and Fine Analysis - Europe H2020-INFRAIA-2014-2015, grant agreement no. 654360. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract no DE-AC02-05CH11231. The authors declare no competing financial interest.
Funding AgencyGrant Number
Ministry of Education (Taipei)UNSPECIFIED
Caltech Space Solar Program InitiativeUNSPECIFIED
Tor Vergata University2DUTOPI
European Research Council (ERC)676598
European Research Council (ERC)654360
Department of Energy (DOE)DE-AC02-05CH11231
Subject Keywords:Transition metal dichalcogenides, photoluminescence, exciton, first-principles, radiative lifetime, Bethe−Salpeter equation
Issue or Number:6
Record Number:CaltechAUTHORS:20180508-101719499
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Official Citation:Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides. Hsiao-Yi Chen, Maurizia Palummo, Davide Sangalli, and Marco Bernardi. Nano Letters 2018 18 (6), 3839-3843. DOI: 10.1021/acs.nanolett.8b01114
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86277
Deposited By: Tony Diaz
Deposited On:08 May 2018 17:45
Last Modified:15 Nov 2021 20:37

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