Durable electrooptic devices comprising ionic liquids

• US 20050162728A1
• Filed: 01/20/2005
• Published: 07/28/2005
• Est. Priority Date: 06/21/2002
• Status: Active Grant

• Current Assignee: Los Alamos National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Burrell, Anthony K., Warner, Benjamin P., McCleskey, T. Mark
• Granted Patent: US 7,119,937 B2
• Time in Patent Office: Days
• US Class Current: 359/273
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• 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 1/157 Structural association of cells with optical devices, e.g. reflectors or illuminating devices
• 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.

Claims

1-17. -17. (canceled)

18. A method for preparing ionic liquid precursor substantially free of colored impurities, comprising:

(a) generating ionic liquid precursor comprising colored impurities; and

(b) exposing the ionic liquid precursor to decolorizing agent, thereby removing the colored impurities.

19. The method of claim 18, wherein the ionic liquid is liquid at room temperature and comprises at least one cation selected from the group consisting of lithium cation and quaternary ammonium cations, and at least one anion selected from the group consisting of trifluoromethylsulfonate (CF₃SO₃⁻

), bis(trifluoromethylsulfonyl)imide ((CF₃SO₂N⁻

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

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

).

20. The method of claim 18, wherein the decolorizing agent comprises carbon.

21. The method of claim 18, wherein the decolorizing agent comprises charcoal or activated carbon.

22. A method for preparing ionic liquid comprising preparing a first solution comprising base and the conjugate acid of the anion of the ionic liquid, preparing a second solution comprising quaternary ammonium halide, and combining the first solution with the second solution.

23. The method of claim 22, wherein the conjugate acid of the anion of the ionic liquid comprises a sulfonic acid, a sulfonylamine, or a bis(sulfonyl)amine.

24. The method of claim 22, wherein the conjugate acid of the anion of the ionic liquid is trifluoromethanesulfonic acid or bis(trifluorosulfonyl)amine.

25. The method of claim 22, wherein the conjugate acid of the anion of the ionic liquid comprises a mineral acid.

26. The method of claim 22, wherein the conjugate acid of the anion of the ionic liquid comprises HBF₄, HPF₆, or HSbF₆.

27. The method of claim 22, wherein the base comprises sodium hydroxide.

28. The method of claim 22, wherein the conjugate acid of the anion of the ionic liquid comprises at least one carbon-fluorine bond.

29. A method for preparing ionic liquid substantially free of colored impurities, comprising:

(a) generating ionic liquid precursor comprising colored impurities;

(c) exposing the ionic liquid precursor to decolorizing agent, thereby removing the colored impurities from the precursor; and

(d) using the purified precursor to prepare ionic liquid.

30. The method of claim 29, wherein the ionic liquid is liquid at room temperature and comprises at least one cation selected from the group consisting of lithium cation and quaternary ammonium cations, and at least one anion selected from the group consisting of trifluoromethylsulfonate (CF₃SO₃⁻

), bis(trifluoromethylsulfonyl)imide ((CF_{3 SO2}N⁻

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

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

).