Purification of carbon nanotubes via selective heating

• US 10,333,069 B2
• Filed: 11/17/2016
• Issued: 06/25/2019
• Est. Priority Date: 04/04/2013
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois, Northwestern University, University of Miami
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Rogers, John A., Wilson, William L., Jin, Sung Hun, Dunham, Simon N., Xie, Xu, Islam, Ahmad, Du, Frank, Huang, Yonggang, Song, Jizhou
• Primary Examiner(s): Sandvik, Benjamin P
• Application Number:
  US15/354,951
• Publication Number:
  US 20170291817A1
• Time in Patent Office: 950 Days
• Field of Search: None
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 2202/22 Electronic properties
• CPC Class Codes: C01B 2202/34 Length
• CPC Class Codes: C01B 32/17 Purification
• CPC Class Codes: G01N 21/62 Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
• CPC Class Codes: H01L 21/02606 Nanotubes carbon nanotubes H10K85/211
• CPC Class Codes: H01M 4/1393 of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H10K 71/13 using printing techniques, e.g. ink-jet printing or screen printing
• CPC Class Codes: H10K 71/311 Purifying organic semiconductor materials
• CPC Class Codes: H10K 85/221 Carbon nanotubes
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention provides methods for purifying a layer of carbon nanotubes comprising providing a precursor layer of substantially aligned carbon nanotubes supported by a substrate, wherein the precursor layer comprises a mixture of first carbon nanotubes and second carbon nanotubes; selectively heating the first carbon nanotubes; and separating the first carbon nanotubes from the second carbon nanotubes, thereby generating a purified layer of carbon nanotubes. Devices benefiting from enhanced electrical properties enabled by the purified layer of carbon nanotubes are also described.

Claims

1. A method for purifying a layer of carbon nanotubes comprising:

providing a precursor layer of substantially aligned carbon nanotubes supported by a substrate, wherein said precursor layer comprises a mixture of metallic carbon nanotubes and semiconducting carbon nanotubes;

covering said precursor layer of carbon nanotubes with a thermocapillary resist, wherein said thermocapillary resist is in thermal contact with at least a portion of said carbon nanotubes; and

applying an electric current to said metallic carbon nanotubes, thereby selectively heating said metallic carbon nanotubes to separate said metallic carbon nanotubes from said semiconducting carbon nanotubes, thereby providing a purified layer of carbon nanotubes comprising at least 50% of said metallic or said semiconducting carbon nanotubes.

2. The method claim 1, wherein said selective heating results from electronic resistance.

3. The method of claim 1, wherein said carbon nanotubes are single-walled carbon nanotubes (SWNTs).

4. The method of claim 1, wherein said carbon nanotubes are multi-walled carbon nanotubes (MWNTs).

5. The method of claim 1, wherein said semiconducting carbon nanotubes do not absorb sufficient energy to overcome the Schottky barrier of said semiconducting carbon nanotubes.

6. The method of claim 1, wherein electric current is an alternating or direct current selected from a range of 0.01 mA to 100 mA.

7. The method of claim 1, wherein said metallic carbon nanotubes and said semiconducting nanotubes of said precursor layer are in electrical contact with a first electrode and a second electrode.

8. The method of claim 7, wherein said step of applying said electric current is performed by applying an electrode bias voltage between said first electrode and said second electrode selected from the range of 0.01 V to 100 V.

9. The method of claim 7, wherein said first and second electrodes are interdigitated.

10. The method of claim 1, wherein said thermocapillary resist comprises a molecular organic species.

11. The method of claim 1, wherein said thermocapillary resist is selected from the group consisting of α

,α

,α

′

-Tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, polymethylmethacrylate (PMMA), polystyrene (PS), poly(styrene-dimethylsiloxane) (PS-PDMS);

oligosaccharide-trimethylsilylstyrene, and polyhedral oligomeric silsesquioxane (POSS).

12. The method of claim 1, wherein said thermocapillary resist has a room temperature viscosity selected from a range of 0.5 Pa·

s to 100 Pas.

13. The method of claim 1, wherein said layer of substantially aligned carbon nanotubes comprises at least 90% semiconducting carbon nanotubes.