Highly Stable Near-Unity Photoluminescence Yield in Monolayer MoS2 by Fluoropolymer Encapsulation and Superacid Treatment

Hyungjin Kim, Der Hsien Lien, Matin Amani, Joel W. Ager, Ali Javey

Research output: Contribution to journalArticlepeer-review

69 Citations (Scopus)


Recently, there has been considerable research interest in two-dimensional (2D) transition-metal dichalcogenides (TMDCs) for future optoelectronic applications. It has been shown that surface passivation with the organic nonoxidizing superacid bis(trifluoromethane)sulfonamide (TFSI) produces MoS2 and WS2 monolayers whose recombination is at the radiative limit, with a photoluminescence (PL) quantum yield (QY) of ∼00%. While the surface passivation persists under ambient conditions, exposure to conditions such as water, solvents, and low pressure found in typical semiconductor processing degrades the PL QY. Here, an encapsulation/passivation approach is demonstrated that yields near-unity PL QY in MoS2 and WS2 monolayers which are highly stable against postprocessing. The approach consists of two simple steps: encapsulation of the monolayers with an amorphous fluoropolymer and a subsequent TFSI treatment. The TFSI molecules are able to diffuse through the encapsulation layer and passivate the defect states of the monolayers. Additionally, we demonstrate that the encapsulation layer can be patterned by lithography and is compatible with subsequent fabrication processes. Therefore, our work presents a feasible route for future fabrication of highly efficient optoelectronic devices based on TMDCs.

Original languageEnglish
Pages (from-to)5179-5185
Number of pages7
JournalACS Nano
Issue number5
Publication statusPublished - 2017 May 23

Bibliographical note

Funding Information:
This work was supported by the Electronic Materials Program funded by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division of the U.S. Department of Energy, under contract no. DE-AC02-05Ch11231.

Publisher Copyright:
© 2017 American Chemical Society.

All Science Journal Classification (ASJC) codes

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


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