Visualizing nanoscale excitonic relaxation properties of disordered edges and grain boundaries in monolayer molybdenum disulfide

Wei Bao, Nicholas J. Borys, Changhyun Ko, Joonki Suh, Wen Fan, Andrew Thron, Yingjie Zhang, Alexander Buyanin, Jie Zhang, Stefano Cabrini, Paul D. Ashby, Alexander Weber-Bargioni, Sefaattin Tongay, Shaul Aloni, D. Frank Ogletree, Junqiao Wu, Miquel B. Salmeron, P. James Schuck

Research output: Contribution to journalArticlepeer-review


Two-dimensional monolayer transition metal dichalcogenide semiconductors are ideal building blocks for atomically thin, flexible optoelectronic and catalytic devices. Although challenging for two-dimensional systems, sub-diffraction optical microscopy provides a nanoscale material understanding that is vital for optimizing their optoelectronic properties. Here we use the 'Campanile' nano-optical probe to spectroscopically image exciton recombination within monolayer MoS2 with sub-wavelength resolution (60 nm), at the length scale relevant to many critical optoelectronic processes. Synthetic monolayer MoS2 is found to be composed of two distinct optoelectronic regions: an interior, locally ordered but mesoscopically heterogeneous two-dimensional quantum well and an unexpected ∼300-nm wide, energetically disordered edge region. Further, grain boundaries are imaged with sufficient resolution to quantify local exciton-quenching phenomena, and complimentary nano-Auger microscopy reveals that the optically defective grain boundary and edge regions are sulfur deficient. The nanoscale structure-property relationships established here are critical for the interpretation of edge- and boundary-related phenomena and the development of next-generation two-dimensional optoelectronic devices.

Original languageEnglish (US)
Article number7993
JournalNature communications
StatePublished - Aug 13 2015
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Biochemistry, Genetics and Molecular Biology
  • General Physics and Astronomy


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