Durable electrooptic devices comprising ionic liquids

• US 6,961,168 B2
• Filed: 12/19/2003
• Issued: 11/01/2005
• Est. Priority Date: 06/21/2002
• Status: Expired due to Fees

• Current Assignee: Ajjer, LLC, Los Alamos National Security LLC (Government of the United States of America)
• 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.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Choi, William
• Application Number:
  US10/741,903
• Publication Number:
  US 20040257633A1
• Time in Patent Office: 683 Days
• Field of Search: 359265-275, 359/321, 359/322, 252/582, 252/583, 252/586
• 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. An electrochromic device suitable for use as an rear-view mirror comprising a first substrate comprising a first surface coated with a transparent conductor;

a second substrate comprising a second surface coated with a second conductor, said second substrate positioned in a substantially parallel relationship with said first substrate and spaced apart from said second substrate by a distance of less than about 250 microns, said first surface facing said second surface, said device further comprising an electrochromic medium disposed between said first substrate and said second substrate, whereby the transmission of light through said electrochromic medium is changed when an electric potential is applied thereto and wherein the resistivity of at least one of said conductors is greater than 20 ohms/square, said electrochromic device having a coloring speed and a bleaching speed of less than 60 seconds at temperature of from about 23 degrees Celsius to about 27 degrees Celsius, wherein said electrochromic medium comprises at least one bridged dye comprising at least one anodic moiety and one cathodic moiety.

2. The electrochromic device of claim 1, wherein the concentration of ions of the electrochromic medium is greater than 1 molar.

3. The electrochromic device of claim 1, wherein said second conductor comprises reflective material.

4. The electrochromic device of claim 1, wherein said second conductor is transparent with a resistivity of greater than 20 ohms/square.

5. An electrochromic device suitable for use as an rear-view mirror comprising a first substrate having a first transparent conductor coated surface, a second substrate having a second conductor coated surface, and a single compartment electrochromic medium comprising ionic liquid having an ionic concentration of cations in excess of 1 molar disposed between said first substrate and said second substrate, said second substrate positioned in a substantially parallel spaced apart relationship from said first substrate at a distance of less than about 250 microns, said first conducting surface facing said second conductor surface, whereby the transmission of light through said electrochromic medium is changed when an electric potential is applied thereto.

6. The electrochromic device of claim 5, wherein the electrolyte comprises a bridged electrochromic dye.

7. The electrochromic device of claim 5, wherein the transparent conductor coating comprises a resistivity greater than 20 ohms/square.

8. 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 disposed between said first substrate and said second substrate, at least one conductive surface comprising a coating of nanostructured material, and an electrochromic dye attached to said nanostructured material, said electrolyte medium comprising ionic liquid comprising at least one anion selected from the group consisting of trifluoromethylsulfonate (CF₃ SO₃), bis(trifluoromethylsulfonyl)imide ((CF₃SO₂)₂N⁻

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

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

), wherein said second substrate is positioned in a substantially parallel spaced apart relationship from said first substrate, and wherein said first conductor surface faces said second conductor surface.

9. The electrochromic device of claim 8, wherein said device comprises a display device.

10. The electrochromic device of claim 8, wherein said ionic liquid comprises at least one cation selected from the group consisting of quaternary ammonium cations.

11. 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 disposed between said first substrate and said second substrate, at least one conductive surface comprising a coating of nanostructured material, and an electrochromic dye attached to said nanostructured material, said electrolyte medium comprising ionic liquid comprising a concentration greater than 1 molar, wherein said second substrate is positioned in a substantially parallel spaced apart relationship from said first substrate, and wherein said first conductor surface faces said second conductor surface.

12. A photochromic device comprising an electrochromic electrode, a light sensitive electrode substantially parallel to and spaced apart from said electrochromic electrode, and an electrolyte medium disposed between said electrochromic electrode and said light sensitive electrode, said electrolyte medium comprising ionic liquid.

13. The photochromic device of claim 12, wherein said electrolyte medium comprising 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⁻

).

14. The photochromic device of claim 12, wherein said light sensitive electrode comprises titania.

15. An electroluminscent device comprising a first substrate having a transparent conductor coated surface, a second substrate having a second conductor coated surface comprising semiconductor nanoparticles, and an electrolyte medium disposed between said first substrate and said second substrate, said electrolyte medium comprising a soluble electroluminescent dye and ionic liquid comprising 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)₃C⁻

), wherein said second substrate is positioned in a substantially parallel spaced apart relationship from said first substrate, and wherein said first conductor surface faces said second conductor surface.

16. The electroluminescent device of claim 15, wherein said electroluminescent dye emits in the near infrared region of the electromagnetic spectrum.

17. The electroluminescent device of claim 15, wherein said electroluminescent dye emits in the visible region of the electromagnetic spectrum.