DURABLE ELECTROOPTIC DEVICES COMPRISING IONIC LIQUIDS

• US 20080266642A1
• Filed: 09/22/2006
• Published: 10/30/2008
• Est. Priority Date: 06/20/2003
• Status: Active Grant

• Current Assignee: Ajjer, LLC, TRIAD National Security, LLC, Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Agrawal, Anoop, Cronin, John P., Burrell, Anthony K., Warner, Benjamin P., McCleskey, T. Mark, Tonazzi, Juan C.L.
• Granted Patent: US 7,450,292 B1
• Time in Patent Office: Days
• US Class Current: 359/270
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: C09K 2211/1029 containing one nitrogen atom as the heteroatom
• 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
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• CPC Class Codes: G02F 2202/022 polymeric
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials

Abstract

Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF₃SO₃⁻), bis(trifluoromethylsulfonyl)imide ((CF₃SO₂)₂N⁻), bis(perfluoroethylsulfonyl)imide ((CF₃CF₂SO₂)₂N⁻) and tris(trifluoromethylsulfonyl)methide ((CF₃SO₂)₃C⁻). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

Claims

1. An electrochromic device, comprising:

a first substrate having a transparent conductor coated surface,

a second substrate having a second conductor coated surface,

an electrolyte medium comprising ionic liquid and disposed between said first substrate and said second substrate, the ionic liquid comprising anions,

at least one conductive surface one at least one of said transparent conductor coated surface and said second conductor coated surface, said conductive surface comprising a coating of nanostructured material,

an electrochromic dye attached to said nanostructured material, wherein the anion of the attached dye is same as the anion of the ionic liquid.

2. The device of claim 1, wherein said electrolyte medium is a solid medium.

3. The device of claim 2, wherein said solid electrolyte medium comprises a plurality of phases or crosslinked polymer.

4. An electrochromic automotive rear-view mirror with an electrolyte comprising an ionic liquid that has at least one of a coloration speed of less than or equal to 10 seconds and a bleach speed of less than or equal to 10 seconds.

5. The electrochromic mirror of claim 4 wherein said electrolyte comprises a bifunctional dye.

6. The electrochromic mirror of claim 4, wherein said mirror darkens to a neutral color when the electrochromic mirror is powered.

7. The electrochromic mirror of claim 4, wherein said mirror is self-erasing.

8. An electrochromic automotive exterior rear-view mirror with an electrolyte comprising an ionic liquid that has at least one of a coloration speed of less than or equal to 30 seconds and a bleach speed of less than or equal to 30 seconds.

9. The electrochromic mirror of claim 8, wherein said electrolyte comprises a bifunctional dye.

10. An electrochromic mirror of claim 8, wherein said mirror darkens to a neutral color when the electrochromic mirror is powered.

11. The electrochromic mirror of claim 8, wherein said mirror is self-erasing.

12. An electro-optic device, comprising:

at least one chamber, and

an electrolyte medium inside the chamber and comprising a compound of the formula

13. The electrooptic device of claim 12, wherein said electrolyte medium comprises a salt.

14. The electrooptic device of claim 12, wherein said electrolyte medium further comprises a UV stabilizer or an electron acceptor that is covalently attached to said compound.

15. The electrooptic device of claim 12, wherein said electrolyte medium comprises an ionic liquid.

16. The electrooptic device of claim 13, wherein said ionic liquid comprises at least one anion selected from the group consisting of trifluoromethylsulfonate (CF₃SO₃⁻

), bis(trifluoromethylsulfonyl)imide ((CF₃SO₂)₂N⁻

), bis(perfluoroethylsulfonyl)imide ((CF₃CF₂SO₂)₂N⁻

) and tris(trifluoromethylsulfonyl)methide ((CF₃SO₂)₃C⁻

).

17. The electrooptic device of claim 13, wherein said electrolyte medium further comprises at least one additive selected from the group consisting of non-ionic cosolvents, polymers, thixotropic agents, and UV stabilizers.

18. The electrooptic device of claim 13, wherein said electrolyte medium further comprises a radical cation of said compound.

19. The electrooptic device of claim 13, wherein said electrolyte medium further comprises at least a second compound that, in combination with said first compound, produces a neutral color when said electrooptic device is powered.

20. The electrooptic device of claim 18, wherein said second compound is a viologen.

21. The electrooptic device of claim 13, wherein said device is a display device.

22. An electrochromic device, comprising:

a first electrode comprising a transparent or translucent substrate, an electrically conducting coating on said substrate, and on said electrically conducting coating a nanostructured film comprising a conducting or semiconducting metal oxide having a first redox chromophore adsorbed thereto,

a second electrode comprising a transparent or translucent substrate, an electrically conducting coating on said substrate, and on the coating a nanostructured film comprising a conducting metal oxide having a second redox chromophore adsorbed thereto

an electrolyte between said first electrode and said second electrode,

wherein at least one of said first redox chromophore and said second redox chromophore comprises a compound of the formula

23. An electrooptic device as in claim 22, wherein at least one of the redox chromophores comprises a metallocene.

24. The electrooptic device of claim 23, wherein the metallocene comprises a ferrocene or a ferrocene derivative.