Project TitleThickness Sorting of Two-Dimensional Nanomaterials
Track Code2014-155
Short Description

Novel method for sorting two dimensional nanomaterials based on thickness

#materials #manufacturing #manufacture/processes #nanotechnology #fabrication


Two-dimensional transition metal dichalcogenides (TMDs) have emerged as leading successors to graphene due to their diverse properties, which depend on sample thickness. Although solution-based exfoliation methods hold promise for scalable production of these materials, existing techniques introduce irreversible structural defects and/or lack sufficient control over the sample thickness. Northwestern researchers have overcome this limitation and demonstrated thickness sorting of pristine molybdenum disulfite (MoS2) by employing isopycnic density gradient ultracentrifugation (DGU) with block copolymer dispersants that effectively reduce the overall buoyant density in aqueous solution. The resulting solution-processed monolayer MoS2 samples exhibit strong photoluminescence without further chemical treatment. Thickness sorting of TMDs is confirmed with AFM and Raman spectroscopy, and atomic-resolution STEM imaging verifies that the sorted TMDs possess high crystal quality with low surface and edge defect density. Since DGU has proven industrial scalability, this approach holds promise for the solution-phase production of monolayered TMDs in emerging large-volume applications including photovoltaics, catalysis, biotechnology, and electronics. 

TagsMANUFACTURE/PROCESSES, MATERIALS: manufacturing, nanotechnology, NANOTECHNOLOGY: fabrication
Posted DateFeb 20, 2015 10:35 AM


Mark C. Hersam*

Jung-Woo T Seo

Joohoon Kang


  • Electronics
  • Optoelectronics
  • Photovoltaics
  • Batteries
  • Catalysis
  • Biotechnology


  • Density gradient ultracentrifugation can be directly applied to transition metal dichalcogenides
  • Proven solution-based manufacturing methods can be used


IP Status

A provisional patent has been filed.

Marketing Contact

Arjan Quist, Ph.D.

Invention Manager

(p) (847) 467-0305