Large-area transparent conductive coatings including doped carbon nanotubes and nanowire composites, and methods of making the same

• US 8,518,472 B2
• Filed: 03/04/2010
• Issued: 08/27/2013
• Est. Priority Date: 03/04/2010
• Status: Expired due to Fees

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Veerasamy, Vijayen S.
• Primary Examiner(s): Cleveland, Michael
• Assistant Examiner(s): TADAYYON ESLAMI, TABASSOM
• Application Number:
  US12/659,353
• Publication Number:
  US 20110217451A1
• Time in Patent Office: 1,272 Days
• Field of Search: 427/58, 977/752, 977/762, 977/842, 977/890
• US Class Current: 427/58
• CPC Class Codes: C09D 11/52 Electrically conductive inks

Abstract

Certain example embodiments of this invention relate to large-area transparent conductive coatings (TCCs) including carbon nanotubes (CNTs) and nanowire composites, and methods of making the same. The σ_dc/σ_opt ratio of such thim films may be improved via stable chemical doping and/or alloying of CNT-based films. The doping and/or alloying may be implemented in a large area coating system, e.g., on glass and/or other substrates. In certain example embodiments, a CNT film may be deposited and then doped via chemical functionalization and/or alloyed with silver and/or palladium. Both p-type and n-type dopants may be used in different embodiments of this invention. In certain example embodiments, silver and/or other nanowires may be provided, e.g., to further decrease sheet resistance. Certain example embodiments may provide coatings that approach, meet, or exceed 90% visible transmission and 90 ohms/square target metrics.

Claims

1. A method of making a coated article comprising a substrate supporting a carbon nanotube (CNT) inclusive thin film, the method comprising:

providing a CNT-inclusive ink;

adjusting rheological properties of the CNT-inclusive ink by adding surfactants to the ink so that any semiconducting CNTs located within the ink are less likely to clump together;

applying the ink having the adjusted rheological properties to the substrate to form an intermediate coating;

providing a material over the intermediate coating; and

doping the intermediate coating with a salt and/or super acid so as to chemically functionalize the intermediate coating in forming the CNT-inclusive thin film,

wherein the material provided over the intermediate coating comprises PVP or is a thin film material comprising zirconia or silica.

2. The method of claim 1, wherein the CNT-inclusive ink consists essentially of double-wall nanotubes when initially provided.

3. The method of claim 1, further comprising using a slot die apparatus to apply the ink having the adjusted rheological properties to the substrate.

4. The method of claim 1, further comprising drying the intermediate coating.

5. The method of claim 1, wherein the doping is performed at substantially the same time as the PVP is provided.

6. The method of claim 1, wherein the super acid is H₂SO₄.

7. The method of claim 1, wherein the salt is a diazonium salt.

8. The method of claim 7, wherein the salt is BDF or OA.

9. The method of claim 1, further comprising substantially planarizing the CNT-inclusive film using the material provided over the intermediate coating.

10. The method of claim 1, further comprising substantially planarizing the CNT-inclusive film by disposing a conductive coating thereon.

11. The method of claim 1, further comprising substantially planarizing the CNT-inclusive film by disposing a thin, partially insulating coating thereon.

12. The method of claim 1, wherein CNT-inclusive film is doped p-type.

13. The method of claim 1, wherein CNT-inclusive film is doped n-type.

14. The method of claim 1, further comprising discharging oxygen or ozone proximate to the substrate to functionalize the intermediate coating and/or the CNT-inclusive film by oxidizing carbon located therein.

15. A method of making a coated article comprising a substrate supporting a carbon nanotube (CNT) inclusive thin film, the method comprising:

providing a CNT-inclusive ink, the CNT-inclusive ink comprising double-wall nanotubes;

adjusting rheological properties of the CNT-inclusive ink to make the CNT-inclusive ink more water-like;

applying the ink having the adjusted rheological properties to the substrate to form an intermediate coating using a slot die apparatus, a layer comprising zirconia being disposed on the substrate and sulphonated with H2SO4 prior to the applying of the ink having the adjusted rheological properties;

drying the intermediate coating or allowing the intermediate coating to dry;

providing an overcoat over the intermediate coating;

doping the intermediate coating with a salt and/or super acid so as to chemically functionalize the intermediate coating in forming the CNT-inclusive thin film; and

substantially planarizing the CNT-inclusive film.

16. The method of claim 15, wherein the overcoat comprises PVP.

17. The method of claim 15, wherein the overcoat comprises PEDOT:

PSS.

18. The method of claim 15, wherein the super acid is H₂SO₄.

19. The method of claim 15, wherein the salt is BDF or OA.

20. A method of making a coated article comprising a substrate supporting a carbon nanotube (CNT) inclusive thin film, the method comprising:

providing a CNT-inclusive ink;

adjusting rheological properties of the CNT-inclusive ink by adding surfactants to the ink so that any semiconducting CNTs located within the ink are less likely to clump together;

applying the ink having the adjusted rheological properties to the substrate to form an intermediate coating;

providing a material over the intermediate coating;

doping the intermediate coating with a salt and/or super acid so as to chemically functionalize the intermediate coating in forming the CNT-inclusive thin film; and

forming silver nanowires, directly or indirectly, on the substrate to provide a long-distance charge transport to reduce the number of carbon nanotube junctions that otherwise would, be present if the silver nanowires were not formed, the silver nanowires being synthesized by reducing silver nitrate in the presence of PVP in ethylene glycol.

21. The method of claim 20, wherein the silver nanowires are 2-5 microns long and 17-80 nm in diameter.

22. The method of claim 20, further comprising dropping a suspension of synthesized silver nanowires on the substrate.

23. The method of claim 20, further comprising:

providing a solution of silver nanowires; and

mixing the solution of silver nanowires into the CNT-inclusive ink before or after rheological properties thereof have been adjusted;

wherein the silver nanowires are formed on the substrate during the applying of the ink having the modified rheological properties to the substrate.