Environmental changes in MoTe<inf>2</inf> excitonic dynamics by defects-activated molecular interaction

Bin Chen, Hasan Sahin, Aslihan Suslu, Laura Ding, Mariana Bertoni, F. M. Peeters, Sefaattin Tongay

Research output: Contribution to journalArticle

92 Citations (Scopus)

Abstract

Monolayers of group VI transition metal dichalcogenides possess direct gaps in the visible spectrum with the exception of MoTe<inf>2</inf>, where its gap is suitably located in the infrared region but its stability is of particular interest, as tellurium compounds are acutely sensitive to oxygen exposure. Here, our environmental (time-dependent) measurements reveal two distinct effects on MoTe<inf>2</inf> monolayers: For weakly luminescent monolayers, photoluminescence signal and optical contrast disappear, as if they are decomposed, but yet remain intact as evidenced by AFM and Raman measurements. In contrast, strongly luminescent monolayers retain their optical contrast for a prolonged amount of time, while their PL peak blue-shifts and PL intensity saturates to slightly lower values. Our X-ray photoelectron spectroscopy measurements and DFT calculations suggest that the presence of defects and functionalization of these defect sites with O<inf>2</inf> molecules strongly dictate their material properties and aging response by changing the excitonic dynamics due to deep or shallow states that are created within the optical band gap. Presented results not only shed light on environmental effects on fundamental material properties and excitonic dynamics of MoTe<inf>2</inf> monolayers but also highlight striking material transformation for metastable 2D systems such as WTe<inf>2</inf>, silicone, and phosphorene.

Original languageEnglish (US)
Pages (from-to)5326-5332
Number of pages7
JournalACS Nano
Volume9
Issue number5
DOIs
StatePublished - May 26 2015

Fingerprint

Molecular interactions
molecular interactions
Monolayers
Defects
defects
tellurium compounds
silicones
Tellurium compounds
visible spectrum
Materials properties
blue shift
transition metals
photoelectron spectroscopy
atomic force microscopy
Optical band gaps
photoluminescence
Silicones
Discrete Fourier transforms
Transition metals
oxygen

Keywords

  • 2D materials
  • environmental stability
  • excitons
  • MoTe<inf>2</inf>
  • photoluminescence

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

Cite this

Environmental changes in MoTe<inf>2</inf> excitonic dynamics by defects-activated molecular interaction. / Chen, Bin; Sahin, Hasan; Suslu, Aslihan; Ding, Laura; Bertoni, Mariana; Peeters, F. M.; Tongay, Sefaattin.

In: ACS Nano, Vol. 9, No. 5, 26.05.2015, p. 5326-5332.

Research output: Contribution to journalArticle

Chen, Bin ; Sahin, Hasan ; Suslu, Aslihan ; Ding, Laura ; Bertoni, Mariana ; Peeters, F. M. ; Tongay, Sefaattin. / Environmental changes in MoTe<inf>2</inf> excitonic dynamics by defects-activated molecular interaction. In: ACS Nano. 2015 ; Vol. 9, No. 5. pp. 5326-5332.
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