TRANSPARENT CARBON NANOTUBE ELECTRODE USING CONDUCTIVE DISPERSANT AND PRODUCTION METHOD THEREOF

• US 20080088219A1
• Filed: 04/13/2007
• Published: 04/17/2008
• Est. Priority Date: 10/17/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: CHOI, Seong Jae, CHOI, Jae Young, YOON, Seon Mi, SHIN, Hyeon Jin, YI, Dong Kee
• Granted Patent: US 8,138,568 B2
• Time in Patent Office: Days
• US Class Current: 313/326
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: H01B 1/127 comprising five-membered aromatic rings in the main chain, e.g. polypyrroles, polythiophenes
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon
• CPC Class Codes: H01J 1/02 Main electrodes
• CPC Class Codes: H01J 9/02 Manufacture of electrodes or electrode systems

Abstract

Disclosed is a transparent carbon nanotube (CNT) electrode using a conductive dispersant. The transparent CNT electrode comprises a transparent substrate and a CNT thin film formed on a surface the transparent substrate wherein the CNT thin film is formed of a CNT composition comprising CNTs and a doped dispersant. Further disclosed is a method for producing the transparent CNT electrode.

The transparent CNT electrode exhibits excellent conductive properties, can be produced in an economical and simple manner by a room temperature wet process, and can be applied to flexible displays. The transparent CNT electrode can be used to fabricate a variety of devices, including image sensors, solar cells, liquid crystal displays, organic electroluminescence (EL) displays and touch screen panels, that are required to have both light transmission properties and conductive properties.

Claims

1. A transparent CNT electrode comprising a transparent substrate and a CNT thin film formed on a surface of the transparent substrate wherein the CNT thin film is formed of a CNT composition comprising CNTs and a doped dispersant.

2. The transparent CNT electrode according to claim 1, wherein the transparent substrate is a transparent inorganic substrate selected from glass or quartz substrates, or a flexible transparent substrate made of a material selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyethylene sulfone, polycarbonate, polystyrene, polypropylene, polyester, polyimide, polyetheretherketone, polyetherimide, acrylic resins, olefin-maleimide copolymers, and norbornene resins.

3. The transparent CNT electrode according to claim 1, wherein the CNTs are selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, rope carbon nanotubes, and combinations thereof.

4. The transparent CNT electrode according to claim 3, wherein the single-walled carbon nanotubes are metallic carbon nanotubes.

5. The transparent CNT electrode according to claim 1, wherein the doped dispersant is a conductive dispersant.

6. The transparent CNT electrode according to claim 5, wherein the conductive dispersant is poly(3,4-ethylenedioxythiophene), a compound having a structure in which a head selected from groups represented by Formula 1 is substituted with one tail or two tails that are the same or different, and selected from groups represented by Formula 2:

[Ar—

(X)_a]_l  

 

(Formula

     1)

wherein Ar is a C₆ aromatic group or a C₄-C₅ heteroaromatic group containing at least one heteroatom selected from sulfur (S), nitrogen (N) and oxygen (O),

X is NH—

or CH═

CH—

,

a is 0 or 1, and

l is an integer from 5 to 60,

7. The transparent CNT electrode according to claim 1, wherein the CNTs and the doped dispersant are mixed in a weight ratio of 1:

0.005 to 1;

100.

8. The transparent CNT electrode according to claim 1, wherein the doped dispersant is a dispersant doped with a p-type dopant selected from the group consisting of Lewis acids, protic acids, transition metal halides, noble metal halides, or organic materials;

or an n-type dopant selected from the group consisting of alkali metals, or alkylammonium ions, including.

9. The transparent CNT electrode according to claim 8, wherein the Lewis acids include PF₅, AsF₅, SbF₅, ClO₄⁻

, BF₄⁻

, BF₃, BCl₃, BBr₃, SO₃, NO₂(SbF₆), NO(SbCl₆), or NO₂(BF₄), the protic acids include H₂SO₄, HClO₄, HNO₃, FSO₃H, or CF₃SO₃H, the transition metal halides include FeCl₃, MoCl₅, WCl₅, SnCl₄, MoF₅, RuF₅, TaBr₅ or SnI₄, the noble metal halides include AuCl₃ or HAuCl₄, the organic materials include benzoquinone, tetrachlorobenzoquinone, tetracyanoquinodimethane or dichlorodicyanobenzoquinone, the alkali metals include Li, Na, K, or Cs, and the alkylammonium ions include tetraethylammonium ions or tetrabutylammonium ions.

10. The transparent CNT electrode according to claim 1, wherein the CNT thin film has a visible light transmittance of 60% or more at 550 nm or 600 nm measured at a CNT thin film thickness of 150 nm.

11. A method for producing a transparent CNT electrode, the method comprising:

(a) preparing a CNT composition comprising a CNT and conductive dispersant;

(b) forming a CNT thin film on a surface of a transparent substrate with the CNT composition; and

(c) doping the conductive dispersant contained in the CNT thin film.

12. The method according to claim 11, wherein step (c) includes the sub-steps of i) doping the CNT thin film formed on the surface of the transparent substrate in a dopant solution, ii) washing the dopant remaining in the CNT thin film, and iii) drying the doped CNT thin film.

13. The method according to claim 11, wherein the CNT composition comprises CNTs and a dispersant solution containing the dispersant in a dispersion medium selected from organic solvents, water, or mixtures thereof.

14. The method according to claim 13, wherein the CNTs and the doped conductive dispersant are mixed in a weight ratio of 1:

0.005 to 1;

100.

15. The method according to claim 11, wherein the dispersant is poly(3,4-ethylenedioxythiophene), or a compound having a structure in which a head selected from groups represented by Formula 1 is substituted with one tail or two tails that are the same or different, and selected from groups represented by Formula 2:

[Ar—

(X)_a]_l  

 

(1)

wherein Ar is a C₆ aromatic group or a C₄-C₅ heteroaromatic group containing at least one heteroatom selected from sulfur (S), nitrogen (N) or oxygen (O),

X is NH—

or CH═

CH—

,

a is 0 or 1, and

l is an integer from 5 to 60,

16. The method according to claim 11, wherein the dispersant is doped with a p-type dopant selected from the group consisting of Lewis acids, protic acids, transition metal halides, noble metal halides, and organic materials;

or an n-type dopant selected from the group consisting of alkali metals, and alkylammonium ions.

17. The method according to claim 16, wherein the Lewis acids include PF₅, AsF₅, SbF₅, ClO₄⁻

, BF₄⁻

, BF₃, BCl₃, BBr₃, SO₃, NO₂(SbF₆), NO(SbCl₆), or NO₂(BF₄), the protic acids include H₂SO₄, HClO₄, HNO₃, FSO₃H, or CF₃SO₃H, the transition metal halides include FeCl₃, MoCl₅, WCl₅, SnCl₄, MoF₅, RuF₅, TaBr₅ or SnI₄, the noble metal halides include AuCl₃ or HAuCl₄, the organic materials include benzoquinone, tetrachlorobenzoquinone, tetracyanoquinodimethane or dichlorodicyanobenzoquinone, the alkali metals include Li, Na, K, or Cs, and the alkylammonium ions include tetraethylammonium ions or tetrabutylammonium ions.

18. The method according to claim 11, wherein the CNT thin film is formed by spin coating, spray coating, filtration, or bar coating.

19. The method according to claim 11, wherein the doping is performed by a vapor phase process with a vapor of iodine, bromine, chlorine, iodine monochloride, iodine trichloride, or iodine monobromide.