Doping of Carbon Nanotube Films for the Fabrication of Transparent Electrodes

• US 20110048508A1
• Filed: 08/26/2009
• Published: 03/03/2011
• Est. Priority Date: 08/26/2009
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Tulevski, Goerge S., Afzali-Ardakani, Ali
• Application Number:
  US12/548,250
• Publication Number:
  US 20110048508A1
• Time in Patent Office: Days
• US Class Current: 136/252
• CPC Class Codes: H10K 30/821 comprising carbon nanotubes
• CPC Class Codes: H10K 71/12 using liquid deposition, e.g. spin coating
• CPC Class Codes: H10K 71/30 Doping active layers, e.g. electron transporting layers
• CPC Class Codes: Y02E 10/549 Organic PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Techniques for increasing conductivity of carbon nanotube films are provided. In one aspect, a method for increasing conductivity of a carbon nanotube film includes the following steps. The carbon nanotube film is formed from a mixture of metallic and semiconducting carbon nanotubes. The carbon nanotubes are exposed to a solution comprising a one-electron oxidant configured to dope the semiconducting carbon nanotubes to increase a conductivity thereof, thereby increasing the overall conductivity of the film. The step of forming the carbon nanotube film can be performed prior to the step of exposing the carbon nanotubes to the one-electron oxidant solution. Alternatively, the step of exposing the carbon nanotubes to the one-electron oxidant solution can be performed prior to the step of forming the carbon nanotube film. A method of fabricating a transparent electrode on a photovoltaic device from a carbon nanotube film is also provided.

Claims

1. A method for increasing conductivity of a carbon nanotube film, comprising the steps of:

forming the carbon nanotube film from a mixture of metallic and semiconducting carbon nanotubes; and

exposing the carbon nanotubes to a solution comprising a one-electron oxidant configured to dope the semiconducting carbon nanotubes to increase a conductivity thereof, thereby increasing the overall conductivity of the film.

2. The method of claim 1, wherein the step of forming the carbon nanotube film is performed prior to the step of exposing the carbon nanotubes to the one-electron oxidant solution.

3. The method of claim 1, wherein the step of exposing the carbon nanotubes to the one-electron oxidant solution is performed prior to the step of forming the carbon nanotube film.

4. The method of claim 1, further comprising the steps of:

preparing the solution of the one-electron oxidant in a solvent;

5. The method of claim 4, wherein the one-electron oxidant comprises triethyloxonium hexachloroantimonate.

6. The method of claim 4, wherein the solvent comprises one or more of methylene chloride, dimethylformamide, chloroform and acetone.

7. The method of claim 1, wherein the step of exposing the carbon nanotubes to the one-electron oxidant in solution further comprises the step of:

soaking the film in the solution.

8. The method of claim 7, wherein the film is soaked in the solution for a duration of about 30 minutes.

9. The method of claim 1, further comprising the step of:

preparing a mixture of the metallic and semiconducting carbon nanotubes dispersed in a liquid medium.

10. The method of claim 9, further comprising the step of:

purifying the mixture.

11. The method of claim 10, wherein the mixture is purified using centrifugation.

12. The method of claim 9, wherein the step of forming the carbon nanotube film further comprises the step of:

depositing the mixture onto a substrate.

13. The method of claim 12, wherein the mixture is deposited on the substrate using one or more of spin-coating, dip-coating or spray coating.

14. The method of claim 12, wherein the substrate comprises at least a portion of a photovoltaic device.

15. A carbon nanotube film having increased conductivity prepared by the method of claim 1.

16. A method of fabricating a transparent electrode on a photovoltaic device from a carbon nanotube film, comprising the steps of:

forming the carbon nanotube film from a mixture of metallic and semiconducting carbon nanotubes on a surface of the photovoltaic device; and

exposing the carbon nanotubes to a solution comprising a one-electron oxidant configured to dope the semiconducting carbon nanotubes to increase a conductivity thereof, thereby increasing the overall conductivity of the film.

17. The method of claim 16, wherein the step of forming the carbon nanotube film is performed prior to the step of exposing the carbon nanotubes to the one-electron oxidant solution.

18. The method of claim 16, wherein the step of exposing the carbon nanotubes to the one-electron oxidant solution is performed prior to the step of forming the carbon nanotube film.

19. The method of claim 16, wherein the step of forming the carbon nanotube film further comprises the step of:

depositing the carbon nanotube mixture onto the surface of the photovoltaic device using one or more of spin-coating, dip-coating and spray coating.

20. The method of claim 16, wherein the step of forming the carbon nanotube film further comprises the steps of:

forming the carbon nanotube film on filter paper using vacuum filtration; and

transferring the carbon nanotube film from the filter paper to the surface of the photovoltaic device.