Displays with low driving voltage and anisotropic particles

• US 7,507,449 B2
• Filed: 05/30/2006
• Issued: 03/24/2009
• Est. Priority Date: 05/30/2006
• Status: Active Grant

• Current Assignee: Iris Optronics Co., Ltd.
• Original Assignee: Industrial Technology Research Institute
• Inventors: Johnson, David M., Chari, Krishnan, Rankin, Charles M. Jr., Irvin, Glen C. Jr.
• Primary Examiner(s): Visconti; Geraldina
• Application Number:
  US11/442,811
• Publication Number:
  US 20070278448A1
• Time in Patent Office: 1,029 Days
• Field of Search: 252/299.01, 428 11- 13, 430/20, 430/270.1
• US Class Current: 428/1.1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: C09K 19/0225 Ferroelectric
• CPC Class Codes: C09K 19/52 characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
• CPC Class Codes: C09K 19/54 Additives having no specific mesophase characterised by their chemical composition
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/03 Viewing layer characterised by chemical composition
• CPC Class Codes: G02F 1/13439 characterised by their electrical, optical, physical properties; materials therefor; method of making
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal
• CPC Class Codes: G02F 1/13775 Polymer-stabilized liquid crystal layers
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: G02F 2203/02 reflective

Abstract

The present invention relates to a high contrast reflective display comprising a substrate, at least one electronically modulated imaging layer, wherein the electronically modulated imaging layer comprises a uniformly thick, close-packed, ordered monolayer of domains of electrically modulated material in a fixed polymer matrix, at least one barrier layer, wherein the barrier layer is conductive in a direction perpendicular to the substrate, and at least one electrically conductive layer. The invention also relates to a method of making the display with a barrier layer comprising anisotropic particles and orienting the anisotropic conductor to produce a barrier layer conductive in a direction perpendicular to the substrate.

Claims

1. A high contrast reflective display comprising a substrate, at least one electronically modulated imaging layer, wherein said electronically modulated imaging layer comprises a uniformly thick, close-packed, ordered monolayer of domains of electrically modulated material in a fixed polymer matrix, at least one barrier layer, wherein said barrier layer is conductive in a direction perpendicular to said substrate, and at least one electrically conductive layer.

2. The high contrast reflective display of claim 1 wherein said electrically modulated material comprises a bistable chiral nematic liquid crystal layer.

3. The high contrast reflective display of claim 1 wherein said at least one uniformly thick, close-packed, ordered monolayer of electrically modulated material is a uniformly thick, hexagonally close packed monolayer of light modulating material.

4. The high contrast reflective display of claim 1 wherein said electronically modulated imaging layer has a thickness of 5 μ

m.

5. The high contrast reflective display of claim 1 wherein said at least one barrier layer comprises at least one anisotropic conductor.

6. The high contrast reflective display of claim 5 wherein said at least one anisotropic conductor comprises carbon nanotubes or metal nanowires.

7. The high contrast reflective display of claim 6 wherein said carbon nanotubes are functionalized.

8. The high contrast reflective display of claim 7 wherein said functionalized carbon nanotubes are functionalized with at least one member selected from the group consisting of carboxylic acid, carboxylate anion, hydroxyl or sulfur containing groups, carbonyl, phosphates, nitrates and combinations thereof.

9. The high contrast reflective display of claim 7 wherein said functionalized carbon nanotubes are functionalized with a covalent surface functionalization comprising carboxylic acid, carboxylic acid salt or mixtures thereof.

10. The high contrast reflective display of claim 7 wherein said functionalized carbon nanotubes have a functionalized percent range of from 0.5 to 5 atomic percent.

11. The high contrast reflective display of claim 7 wherein said functionalized carbon nanotubes are functionalized with a sulfur containing group selected from:

R—

SO_xZ_y

wherein R is a carbon within the lattice of a single walled carbon nanotube;

x ranges from 1-3;

Z may be a Hydrogen atom or a metal cation such metals as Na, Mg, K, Ca, Zn, Mn, Ag, Au, Pd, Pt, Fe, Co; and

y ranges from 0-1.

12. The high contrast reflective display of claim 11 wherein said sulfur containing groups comprise at least one member selected from the group consisting of sulfonic acid, sulfonic acid and the corresponding anions or mixtures thereof.

13. The high contrast reflective display of claim 7 wherein said functionalized carbon nanotubes are functionalized with a covalent surface functionalization comprising sulfonic acid or a sulfonic acid salt or mixtures thereof.

14. The high contrast reflective display of claim 7 wherein said functionalized carbon nanotubes are functionalized at any point on the single walled carbon nanotube, that is, on the external or internal surface, open or closed end, or sidewall.

15. The high contrast reflective display of claim 6 wherein said carbon nanotubes have minimal or no carbonaceous impurities or metal impurities.

16. The high contrast reflective display of claim 6 wherein said carbon nanotubes are single walled carbon nanotubes.

17. The high contrast reflective display of claim 16 wherein said single walled carbon nanotubes are metallic single walled carbon nanotubes.

18. The high contrast reflective display of claim 16 wherein said single walled carbon nanotubes are prepared by applying a mixture containing:

a) a single walled carbon nanotube according to Formula I;

19. The high contrast reflective display of claim 1 wherein said single walled carbon nanotubes comprise a bundle of single walled carbon nanotubes.

20. The high contrast reflective display of claim 6 wherein said metal nanowires.

21. The high contrast reflective display of claim 1 wherein said metal nanowires comprise silver, gold, palladium, platinum, nickel, aluminum, copper or alloys thereof.

22. The high contrast reflective display of claim 1 wherein said barrier layer has anisotropic conductivity solely in the z-direction.

23. The high contrast reflective display of claim 1 wherein said barrier layer further comprises a binder.

24. The high contrast reflective display of claim 7 wherein said binder comprises polymer in a helix configuration.

25. The high contrast reflective display of claim 7 wherein said binder comprises gelatin.

26. The high contrast reflective display of claim 1 further comprising at least one conductive layer.

27. The high contrast reflective display of claim 26 wherein said barrier layer is located between said electronically modulated imaging layer and said at least one conductive layer.

28. The high contrast reflective display of claim 1 wherein said at least one conductive layer comprises a first conductive layer located between said support and said electronically modulated imaging layer and a second conductive layer located on the side of said electronically modulated imaging layer opposite said support, wherein said barrier layer is located between said electronically modulated imaging layer and said second conductive layer.

29. The high contrast reflective display of claim 1 wherein said second conductive layer comprises screen-printed conductive ink.

30. The high contrast reflective display of claim 1 wherein said high contrast reflective display utilizes a driving voltage of less than 50 volts.

31. A method of making a high contrast reflective display comprising:

providing a substrate;

applying a first conductive layer;

applying at least one layer of domains of electrically modulated material in a polymer matrix;

drying the at least one applied layer of said domains of electrically modulated material in a polymer matrix at a temperature above the chill set temperature or sol-gel transition temperature of said polymer matrix to permit self-assembly of said domains of electrically modulated material into a close-packed monolayer of said domains of electrically modulated material; and

fixing said polymer matrix to preserve said close-packed monolayer of domains of electrically modulated material;

applying a barrier layer comprising anisotropic particles;

orienting said anisotropic conductor to produce a barrier layer conductive in a direction perpendicular to said substrate; and

applying a second conductive layer.

32. The method of claim 31 wherein said at least one anisotropic conductor comprises carbon nanotubes or metal nanowires.

33. The method of claim 32 wherein said carbon nanotubes are functionalized.

34. The method of claim 33 wherein said functionalized carbon nanotubes are functionalized with a covalent surface functionalization comprising carboxylic acid, carboxylic acid salt or mixtures thereof.

35. The method of claim 33 wherein said functionalized carbon nanotubes are functionalized with a covalent surface functionalization comprising sulfonic acid or a sulfonic acid salt or mixtures thereof.

36. The method of claim 32 wherein said carbon nanotubes are single walled carbon nanotubes.

37. The method of claim 31 wherein said barrier layer further comprises a binder.

38. The method of claim 37 wherein said binder comprises gelatin.

39. A method of making a high contrast reflective display comprising:

providing a substrate;

applying a conductive layer;

applying at least one layer of domains of electrically modulated material in a polymer matrix;

drying the at least one applied layer of said domains of electrically modulated material in a polymer matrix at a temperature above the chill set temperature or sol-gel transition temperature of said polymer matrix to permit self-assembly of said domains of electrically modulated material into a close-packed monolayer of said domains of electrically modulated material; and

fixing said polymer matrix to preserve said close-packed monolayer of domains of electrically modulated material;

applying a barrier layer comprising anisotropic particles; and

orienting said anisotropic particles to produce a barrier layer conductive in a direction perpendicular to said substrate.

40. The method of claim 39 wherein said conductive layer is applied after said barrier layer.