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Intellectual Property Office

Nanocrystal Native Ligand Stripping IB-3124

APPLICATIONS OF TECHNOLOGY:

  • LEDs
  • Photovoltaic panels
  • Electrochromic displays and windows
  • Thermoelectric devices
  • Integrated circuits
  • Electrodes for energy storage
  • Nanotechnology and nanobiotechnology research

ADVANTAGES:

  • Facilitates integration of nanocrystals for lower cost electronic and electrochemical devices
  • Does not etch or oxidize surfaces
  • Fast, homogeneous stripping of native ligands
  • Effective for nanocrystal films and dispersions
  • Strips ligands from virtually any nanocrystal surface
  • Inexpensive, scalable and easy to use

ABSTRACT:

Efforts to integrate nanocrystals in new technologies have been stymied by the presence of insulating organic ligands that coat their surfaces, but are nevertheless necessary for controlling the growth trajectory, composition, and morphology during synthesis. Brett Helms and Delia Milliron at Berkeley Lab have found that Meerwein’s and related trialkyloxonium salts (R3OBF4, R3OPF6, etc.), when introduced to nanocrystals, quickly and completely strip these organic ligands from nanocrystals arrayed on film or suspended colloidal dispersions used to create nanoinks. They have also shown that stripped nanocrystal films can be highly conductive of both electrons and ions, pointing to future, new applications.

Conventional ligand-stripping methods are limited by the damage they inflict on nanocrystals. Until now, chemical processes that break the ligand bonds with the crystals can either etch or oxidize nanoscale surfaces, sharply reducing or destroying their advantageous physical characteristics. By uniquely repurposing Meerwein’s salt, a common reagent, the Berkeley Lab team found an extraordinarily efficient way to create bare surfaces on virtually all nanocrystal surfaces tested to date.

Initial applications are likely to be in the development of quantum dot LEDs, but the technology can also be employed in the fabrication of integrated circuits, photovoltaic panels, electrochromic displays or windows, thermoelectrics, and electrodes for energy storage. Dispersions of bare nanocrystals are also useful in preparing materials for nanomedicine, theranostics, and medical imaging.

DEVELOPMENT STAGE:  Bench-scale prototype.

STATUS: Issued U. S. Patent # 9,595,363. Available for licensing or collaborative research.

FOR MORE INFORMATION:

Rosen, E.L., Buonsanti, R., Llordes, A., Sawvel, A.M., Milliron, D.J., Helms, B.A., “Exceptionally Mild Reactive Stripping of Native Ligands from Nanocrystal Surfaces by Using Meerwein’s Salt,” Angewandte Chemi International Edition, Vol. 51, pp. 684-689, 2012.

Duong, J.T., Bailey, M.J., Pick, T.E., McBride, P.M., Rosen, E.L., Buonsanti, R., Milliron, D.J., Helms, B.A. “Efficient Polymer Passivation of Ligand-Stripped Nanocrystal Surfaces,” Journal of Polymer Science Part A: Polymer Chemistry, 2012.

Risbud, A. “Nanocrystals Go Bare: Berkeley Lab Researchers Strip Material’s Tiny Tethers,” Berkeley Lab News Center, December 8, 2011.

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

Scalable Methods for Growing, Shaping and Placing Nanostructures, IB-2047

REFERENCE NUMBER: IB-3124