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

doi:10.1021/acs.nanolett.8b01114

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

Abstract

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.

Authors:

Chen, Hsiao-Yi ^[1];

^[2];

^[3];

^[4]

California Inst. of Technology (CalTech), Pasadena, CA (United States). Dept. of Applied Physics and Materials Science, Dept. of Physics
Dipartimento di Fisica and INFN, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
Consiglio Nazionale delle Ricerche (CNR), Monterotondo Scalo (Italy). Division of Ultrafast Processes in Materials (FLASHit)
California Inst. of Technology (CalTech), Pasadena, CA (United States). Dept. of Applied Physics and Materials Science

Publication Date:: 2018-05-07

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Univ. of California, Oakland, CA (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1543682

Grant/Contract Number:: AC02-05CH11231

Resource Type:: Accepted Manuscript

Journal Name:: Nano Letters

Additional Journal Information:: Journal Volume: 18; Journal Issue: 6; Journal ID: ISSN 1530-6984

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; Chemistry; Science & Technology - Other Topics; Materials Science; Physics

Citation Formats


                    Chen, Hsiao-Yi, Palummo, Maurizia, Sangalli, Davide, and Bernardi, Marco. Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides.  United States: N. p., 2018. 
        Web.  doi:10.1021/acs.nanolett.8b01114.

Copy to clipboard


                    Chen, Hsiao-Yi, Palummo, Maurizia, Sangalli, Davide, & Bernardi, Marco. Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides.  United States.  doi:10.1021/acs.nanolett.8b01114.

Copy to clipboard


                    Chen, Hsiao-Yi, Palummo, Maurizia, Sangalli, Davide, and Bernardi, Marco. Mon .  
        "Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides".  United States.  doi:10.1021/acs.nanolett.8b01114.  https://www.osti.gov/servlets/purl/1543682.

Copy to clipboard


                    
@article{osti_1543682,

  title        = {Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides},

  author       = {Chen, Hsiao-Yi and Palummo, Maurizia and Sangalli, Davide and Bernardi, Marco},

  abstractNote = {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.},

  doi          = {10.1021/acs.nanolett.8b01114},

  journal      = {Nano Letters},

  number       = 6,

  volume       = 18,

  place        = {United States},

  year         = {2018},

  month        = {5}

}

Copy to clipboard

Journal Article:

Free Publicly Available Full Text

Accepted Manuscript (DOE)

Publisher's Version of Record

DOI: 10.1021/acs.nanolett.8b01114

Other availability

Search WorldCat to find libraries that may hold this journal

Citation Metrics:

Cited by: 11 works

Citation information provided by
Web of Science

Save / Share:

Export Metadata

Save to My Library

Works referencing / citing this record:

Saddle-Point Excitons and Their Extraordinary Light Absorption in 2D β-Phase Group-IV Monochalcogenides
journal, October 2018

Luo, Nannan; Wang, Chong; Jiang, Zeyu
Advanced Functional Materials, Vol. 28, Issue 46
DOI: 10.1002/adfm.201804581

Out-of-plane orientation of luminescent excitons in two-dimensional indium selenide
journal, September 2019

Brotons-Gisbert, Mauro; Proux, Raphaël; Picard, Raphaël
Nature Communications, Vol. 10, Issue 1
DOI: 10.1038/s41467-019-11920-4

Dimensionality and anisotropicity dependence of radiative recombination in nanostructured phosphorene
journal, January 2019

Wu, Feng; Rocca, Dario; Ping, Yuan
Journal of Materials Chemistry C, Vol. 7, Issue 41
DOI: 10.1039/c9tc02214g

Precise radiative lifetimes in bulk crystals from first principles: the case of wurtzite gallium nitride
journal, November 2019

Jhalani, Vatsal A.; Chen, Hsiao-Yi; Palummo, Maurizia
Journal of Physics: Condensed Matter, Vol. 32, Issue 8
DOI: 10.1088/1361-648x/ab5563

Carrier recombination mechanism at defects in wide band gap two-dimensional materials from first principles
journal, August 2019

Wu, Feng; Smart, Tyler J.; Xu, Junqing
Physical Review B, Vol. 100, Issue 8
DOI: 10.1103/physrevb.100.081407

Fundamental exciton linewidth broadening in monolayer transition metal dichalcogenides
journal, February 2019

Gupta, Garima; Majumdar, Kausik
Physical Review B, Vol. 99, Issue 8
DOI: 10.1103/physrevb.99.085412

Strain-induced effects on the electronic properties of 2D materials
journal, January 2020

Postorino, Sara; Grassano, Davide; D’Alessandro, Marco
Nanomaterials and Nanotechnology, Vol. 10
DOI: 10.1177/1847980420902569

Similar Records in DOE PAGES and OSTI.GOV collections:

Exchange-driven intravalley mixing of excitons in monolayer transition metal dichalcogenides

Journal Article Guo, Liang ; Wu, Meng ; Cao, Ting ; ... - Nature Physics

Monolayer transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) semiconductors for application in optoelectronics. Their optical properties are dominated by two series of photo-excited exciton states—A (XA) and B (XB)1,2—that are derived from direct interband transitions near the band extrema. These exciton states have large binding energies and strong optical absorption3,4,5,6, and form an ideal system to investigate many-body effects in low dimensions. Because spin–orbit coupling causes a large splitting between bands of opposite spins, XA and XB are usually treated as spin-polarized Ising excitons, each arising from interactions within a specific set of states induced by interband transitions betweenmore »« less
DOI: 10.1038/s41567-018-0362-y
Exchange-driven intravalley mixing of excitons in monolayer transition metal dichalcogenides

Journal Article Guo, Liang ; Wu, Meng ; Cao, Ting ; ... - Nature Physics

Monolayer transition metal dichalcogenides (TMDCs) are promising two-dimensional (2D) semiconductors for application in optoelectronics. Their optical properties are dominated by two series of photo-excited exciton states—A (XA) and B (XB) 1,2 —that are derived from direct interband transitions near the band extrema. These exciton states have large binding energies and strong optical absorption 3–6 , and form an ideal system to investigate many-body effects in low dimensions. Because spin–orbit coupling causes a large splitting between bands of opposite spins, XA and XB are usually treated as spin-polarized Ising excitons, each arising from interactions within a specific set of states inducedmore »« less
DOI: 10.1038/s41567-018-0362-y
Approaching the intrinsic photoluminescence linewidth in transition metal dichalcogenide monolayers

Journal Article Ajayi, Obafunso A. ; Ardelean, Jenny V. ; Shepard, Gabriella D. ; ... - 2D Materials

Excitonic states in monolayer transition metal dichalcogenides (TMDCs) have been the subject of extensive recent interest. Their intrinsic properties can, however, be obscured due to the influence of inhomogeneity in the external environment. Here we report methods for fabricating high quality TMDC monolayers with narrow photoluminescence (PL) linewidth approaching the intrinsic limit. We find that encapsulation in hexagonal boron nitride (h-BN) sharply reduces the PL linewidth, and that passivation of the oxide substrate by an alkyl monolayer further decreases the linewidth and also minimizes the charged exciton (trion) peak. The combination of these sample preparation methods results in much reducedmore »« less
Cited by 39
DOI: 10.1088/2053-1583/aa6aa1

Full Text Available
Long-lived nanosecond spin relaxation and spin coherence of electrons in monolayer MoS₂ and WS₂

Journal Article Yang, Luyi ; Sinitsyn, Nikolai A. ; Chen, Weibing ; ... - Nature Physics

The recently discovered monolayer transition metal dichalcogenides (TMDCs) provide a fertile playground to explore new coupled spin–valley physics. Although robust spin and valley degrees of freedom are inferred from polarized photoluminescence (PL) experiments PL timescales are necessarily constrained by short-lived (3–100 ps) electron–hole recombination9, 10. Direct probes of spin/valley polarization dynamics of resident carriers in electron (or hole)-doped TMDCs, which may persist long after recombination ceases, are at an early stage. Here we directly measure the coupled spin–valley dynamics in electron-doped MoS₂ and WS₂ monolayers using optical Kerr spectroscopy, and reveal very long electron spin lifetimes, exceeding 3 ns atmore »« less
Cited by 78
DOI: 10.1038/nphys3419

Full Text Available
Order of magnitude enhancement of monolayer MoS₂ photoluminescence due to near-field energy influx from nanocrystal films

Journal Article Guo, Tianle ; Sampat, Siddharth ; Zhang, Kehao ; ... - Scientific Reports

Two-dimensional transition metal dichalcogenides (TMDCs) like MoS₂ are promising candidates for various optoelectronic applications. The typical photoluminescence (PL) of monolayer MoS₂ is however known to suffer very low quantum yields. We demonstrate a 10-fold increase of MoS₂ excitonic PL enabled by nonradiative energy transfer (NRET) from adjacent nanocrystal quantum dot (NQD) films. The understanding of this effect is facilitated by our application of transient absorption (TA) spectroscopy to monitor the energy influx into the monolayer MoS₂ in the process of ET from photoexcited CdSe/ZnS nanocrystals. In contrast to PL spectroscopy, TA can detect even non-emissive excitons, and we register anmore »« less
Cited by 1
DOI: 10.1038/srep41967

Full Text Available

Similar Records

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

Abstract

Citation Formats

Saddle-Point Excitons and Their Extraordinary Light Absorption in 2D β-Phase Group-IV Monochalcogenides journal, October 2018

Out-of-plane orientation of luminescent excitons in two-dimensional indium selenide journal, September 2019

Dimensionality and anisotropicity dependence of radiative recombination in nanostructured phosphorene journal, January 2019

Precise radiative lifetimes in bulk crystals from first principles: the case of wurtzite gallium nitride journal, November 2019

Carrier recombination mechanism at defects in wide band gap two-dimensional materials from first principles journal, August 2019

Fundamental exciton linewidth broadening in monolayer transition metal dichalcogenides journal, February 2019

Strain-induced effects on the electronic properties of 2D materials journal, January 2020

Saddle-Point Excitons and Their Extraordinary Light Absorption in 2D β-Phase Group-IV Monochalcogenides
journal, October 2018

Out-of-plane orientation of luminescent excitons in two-dimensional indium selenide
journal, September 2019

Dimensionality and anisotropicity dependence of radiative recombination in nanostructured phosphorene
journal, January 2019

Precise radiative lifetimes in bulk crystals from first principles: the case of wurtzite gallium nitride
journal, November 2019

Carrier recombination mechanism at defects in wide band gap two-dimensional materials from first principles
journal, August 2019

Fundamental exciton linewidth broadening in monolayer transition metal dichalcogenides
journal, February 2019

Strain-induced effects on the electronic properties of 2D materials
journal, January 2020