Electrochromic media for producing a preselected color

• US 6,141,137 A
• Filed: 04/26/1999
• Issued: 10/31/2000
• Est. Priority Date: 08/26/1998
• Status: Expired due to Term

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Guarr, Thomas F., Byker, Harlan J., Winkle, Derick D.
• Primary Examiner(s): Ben, Loha
• Application Number:
  US09/299,490
• Time in Patent Office: 554 Days
• Field of Search: 359/265, 359/272, 359/273, 359/275, 359/321, 359/322, 252/583, 252/600
• US Class Current: 359/265
• CPC Class Codes: C07D 213/22 containing two or more pyridine rings directly linked together, e.g. bipyridyl
• CPC Class Codes: C07D 241/36 condensed with carbocyclic rings or ring systems
• CPC Class Codes: C07D 241/46 Phenazines
• CPC Class Codes: C09K 9/02 Organic tenebrescent materials
• CPC Class Codes: G02F 1/1503 caused by oxidation-reduction reactions in organic liquid solutions, e.g. viologen solutions

Abstract

Electrochromic compositions suitable for use in electrochromic media in electrochromic devices contain minimally two electrochromic compounds of the same redox type, whose redox potentials are greater than 30 mV. The lower redox potential electrochromic compound makes a large contribution to the absorbancy of the electrochromic medium despite being present in only minor concentration.

Claims

1. An electrochromic medium capable of producing a pre-selected color, comprising at least three electroactive compounds, two of which are of the same redox type and another which is of a complementary redox type, where one of said two electroactive compounds of the same redox type has a more easily accessible electrochemically activated redox state than the other by minimally 30 mV, and where two of the at least three electroactive compounds are electrochromic.

2. The electrochromic medium of claim 1, where said at least three electroactive compounds comprise at least two anodic electroactive compounds and at least one cathodic electroactive compound.

3. The electrochromic medium of claim 2, wherein said at least one cathodic electrochromic compound is a dipyridinium compound.

4. The electrochromic medium of claim 2, wherein said at least one anodic electrochromic compound is a 5,10-dihydrophenazine compound.

5. The electrochromic medium of claim 2, wherein said electroactive compounds are contained in a polar organic solvent.

6. The electrochromic medium of claim 1, where said at least three electroactive compounds comprise at least two cathodic electroactive compounds and at least one anodic electroactive compound.

7. The electrochromic medium of claim 6, wherein said at least one cathodic electrochromic compound is a dipyridinium compound.

8. The electrochromic medium of claim 6, wherein the said electroactive compounds are contained in a polar organic solvent.

9. The electrochromic medium of claim 1, where said more easily accessible electrochemically activated state is more accessible by minimally 40 mV.

10. The electrochromic medium of claim 1, wherein said electroactive compound of the same redox type whose redox state is more easily accessible is present in the amount of 28 mol percent or less of the total electrochromic compounds of the same type.

11. The electrochromic medium of claim 1, wherein said electroactive compound of the same redox type whose redox state is more easily accessible is present in the amount of 25 mol percent or less of the total electrochromic compounds of the same type.

12. The electrochromic medium of claim 1, wherein said electroactive compound of the same redox type whose redox state is more easily accessible is present in the amount of 20 mol percent or less of the total electrochromic compounds of the same type.

13. The electrochromic medium of claim 1, where said electrochromic medium does not exhibit staging.

14. The electrochromic medium of claim 1, wherein said electrochromic compounds are selected from 5,10-dihydrophenazine compounds and dipyridinium compounds.

15. The electrochromic medium of claim 1, wherein said electrochromic medium further comprises a cross-linked polymer matrix.

16. An electrochromic display device light filter, comprising:

(a) a cavity containing the electrochromic medium of claim 1, said cavity defined by;

(b) a first transparent substrate which is an integral part of a display device, said substrate having deposited thereon, a transparent conductive electrode on the side of said substrate defining said cavity;

(c) a second substrate having deposited thereon a transparent conductive electrode on the side of said second substrate defining said cavity; and

(d) a seal disposed generally along the peripheral edge of said first and second substrate.

17. The electrochromic display device light filter of claim 16, where said display device is a CRT.

18. The electrochromic display device light filter of claim 16, where said light filter produces a gray color.

19. The electrochromic display device light filter of claim 16, wherein said display device filter is positioned between said display device and a human operator.

20. An electrochromic medium capable of producing a pre-selected color, comprising at least three electroactive compounds, two of which are of the same redox type and another which is of a complementary redox type, where one of said two electroactive compounds of the same redox type has a more accessible electrochemically activated redox state and is present at a concentration of less than 28 mol percent of the total electroactive compounds of the same redox type, and where two of the at least three electroactive compounds are electrochromic.

21. The electrochromic medium of claim 20, wherein said at least three electroactive compounds comprise at least two anodic electroactive compounds and at least one cathodic electroactive compound.

22. The electrochromic medium of claim 20, wherein said at least three electroactive compounds comprise at least two cathodic electroactive compounds and at least one anodic electroactive compound.

23. The electrochromic medium of claim 20, wherein the first of said at least two electroactive compounds of the same redox type has a more easily accessible electrochemically activated redox sate than the other by minimally 30 mV.

24. The electrochromic medium of claim 20, wherein the first of said at least two electroactive compounds of the same redox type has a more easily accessible electrochemically activated redox state than the other by minimally 40 mV.

25. The electrochromic medium of claim 20, wherein said electrochromic medium further comprises a cross-linked polymer matrix.

26. The electrochromic medium of claim 20, where said electrochromic medium does not exhibit staging.

27. The electrochromic medium of claim 20, where said pre-selected color is gray.

28. An electrochromic display device light filter, comprising:

(a) a cavity containing the electrochromic medium of claim 20, said cavity defined by;

(b) a first transparent substrate which is adapted to be positioned onto a display device, said substrate having deposited thereon a transparent conductive electrode on the side of said substrate defining said cavity;

(c) a second substrate having deposited thereon a transparent conductive electrode on the side of said second substrate defining said cavity; and

(d) a seal disposed generally along the peripheral edge of said first and second substrate.

29. The electrochromic display device light filter of claim 28, where said display device is a CRT.

30. The electrochromic display device light filter of claim 28, where said light filter produces a gray color.

31. The electrochromic display device light filter of claim 28, further comprising a display device placed on an opposed side of said display device filter and a human operator.

32. An electrochromic medium capable of producing a pre-selected color, comprising at least three electroactive compounds, two of which are of the same redox type and another which is of a complementary redox type, where one of said two electroactive compounds of the same redox type has a more easily accessible electrochemically activated redox state and contributes to the absorption spectrum of the electrochemically activated state of the medium to a greater extent expected based solely on its abundance in the medium.