Reversible electrochemical mirror

• US 5,923,456 A
• Filed: 12/19/1997
• Issued: 07/13/1999
• Est. Priority Date: 12/19/1997
• Status: Expired due to Term

• Current Assignee: Teledyne Scientific & Imaging, LLC (Teledyne Technologies Incorporated)
• Original Assignee: Rockwell International Corporation
• Inventors: Warren, Leslie F. Jr., Tench, D. Morgan
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): Lester, Evelyn A.
• Application Number:
  US08/994,412
• Time in Patent Office: 571 Days
• Field of Search: 359/265, 359/266, 359/271, 359/272, 359/275
• US Class Current: 359/266
• CPC Class Codes: G02F 1/1506 caused by electrodeposition, e.g. electrolytic deposition of an inorganic material on or close to an electrode
• CPC Class Codes: G02F 1/155 Electrodes

Abstract

An electrochemical mirror includes a transparent first electrode and a second electrode distributed in localized areas. An electrolytic solution is disposed between the first and second electrodes and contains ions of a metal which can electrodeposit on the first and second electrodes. A negative electrical potential applied to the first electrode causes deposited metal to be dissolved from the second electrode into the electrolytic solution and to be electrodeposited from the solution onto the first electrode, thereby affecting the propagation of electromagnetic radiation through the mirror. A surface modification layer applied to the first electrode ensures that the electrodeposit is substantially uniform, resulting in a mirror layer which increases the reflectivity of the mirror. Conversely, a positive electrical potential applied to the first electrode causes deposited metal to be dissolved from the first electrode and electrodeposited from the solution onto the second electrode, thereby increasing the transmissivity of the mirror.

Claims

1. An electrochemical mirror for reversibly controlling the propagation of electromagnetic radiation, comprising:

a first electrode which is substantially transparent to the radiation;

a surface modification layer disposed on the first electrode;

a second electrode which is distributed in localized areas;

an electrolytic solution disposed between and in electrical contact with the first and second electrodes;

a plurality of ions of a metal capable of electrodeposition on the first and second electrodes, the ions being soluble in the electrolytic solution; and

a plurality of atoms of said metal deposited on either the first or the second electrode,

such that a negative electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the second electrode into the solution and to be electrodeposited from the solution onto the first electrode, the surface modification layer facilitating substantially uniform nucleation of the electrodeposited metal on the first electrode, and

such that a positive electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the first electrode and electrodeposited from the solution onto the second electrode,

the amount of deposited metal subsisting on the first electrode affecting the reflectivity of the mirror for the radiation.

2. The mirror of claim 1, wherein the second electrode is substantially transparent to the radiation.

3. The mirror of claim 1, wherein the second electrode is distributed so as to block the radiation in a desired pattern.

4. The mirror of claim 1, further comprising:

a first substrate which is substantially transparent to the radiation, the first electrode being disposed on the first substrate; and

a second substrate which is substantially transparent to the radiation, the second electrode being distributed in localized areas on the second substrate.

5. The mirror of claim 4, wherein

the second substrate is an electrically insulating substrate and

wherein the second electrode is a continuous electrical conductor.

6. The mirror of claim 5, wherein the second electrode is arranged in a conductive mesh pattern.

7. The mirror of claim 4, wherein the second substrate is an electrically conducting substrate and the second electrode is a discontinuous electrical conductor having a relatively low overvoltage for electrodeposition of the metal relative to the second substrate.

8. The mirror of claim 7, wherein the second electrode is arranged in a dot matrix pattern.

9. The mirror of claim 5, wherein the second electrode is an electrically continuous grid of an electrochemically stable metal deposited on the second substrate.

10. The mirror of claim 9, wherein the electrochemically stable metal of the second electrode grid includes at least one metal selected from the group consisting of Au, Cr, Ir, Ni, Os, Pd, Pt, Re, Rh, Ru and stainless steel.

11. The mirror of claim 4, further comprising an underlayer between the second electrode and the second substrate to improve adhesion between the second electrode and the second substrate.

12. The mirror of claim 11, wherein the underlayer includes at least one metal selected from the group consisting of chromium, hafnium, molybdenum, nickel, titanium, tungsten and zirconium.

13. The mirror of claim 4, wherein the first electrode is disposed uniformly on the first substrate.

14. The mirror of claim 4, wherein the first electrode is disposed in a pattern on the first substrate.

15. The mirror of claim 4, wherein the first electrode is an electrically conductive oxide coating deposited on the first substrate.

16. The mirror of claim 15, wherein the electrically conductive oxide coating is selected from the group consisting of aluminum (doped) zinc oxide, antimony (doped) tin oxide, fluorine (doped) tin oxide, indium oxide, and indium tin oxide.

17. The mirror of claim 4, wherein the surface modification layer is a thin layer of an electrochemically inert metal which is electrochemically more stable towards oxidation in the electrolytic solution than the electrodeposited metal.

18. The mirror of claim 17, wherein the inert metal layer includes at least one metal selected from the group consisting of Au, Ir, Os, Pd, Pt, Re, Rh and Ru.

19. The mirror of claim 4, further comprising an underlayer between the first electrode and the surface modification layer to improve adhesion between the first electrode and the surface modification layer.

20. The mirror of claim 19, wherein the underlayer includes at least one metal selected from the group consisting of chromium, halfnium, molybdenum, nickel, titanium, tungsten and zirconium.

21. The mirror of claim 4, wherein the first and second substrates are glass.

22. The mirror of claim 4, wherein the first and second substrates are a plastic.

23. The mirror of claim 22, wherein the plastic first and second substrates are selected from the group consisting of polycarbonate resins and polyurethane resins.

24. The mirror of claim 4, wherein the electrolytic solution is a solution containing water.

25. The mirror of claim 24 wherein the electrolytic solution further comprises a gelling agent to form a gel electrolyte.

26. The mirror of claim 25, wherein the gelling agent is selected from the group consisting of gelatin, polyacrylamide, polyacrylates derived from polyacrylic acid, polyvinylalcohol, polyvinylpyrrolidine, cellulose derivatives, and finely divided silica.

27. The mirror of claim 4, wherein the electrolytic solution is a non-aqueous solution.

28. The mirror of claim 27, wherein the electrolytic solution further comprises an electrochemically inert gelling agent to form a non-aqueous gel electrolyte.

29. The mirror of claim 28, wherein the gelling agent is selected from the group consisting of polyacrylamide, polyacrylic acid, polyacrylonitrile, polycarbonate resin, polymethylmethacrylate, polypropylenecarbonate, polyvinylalcohol, polyvinylidinefluoride, polyvinylpyrrolidine, and finely divided silica.

30. The mirror of claim 4, wherein the metal ions are selected from the group consisting of Ag⁺, Bi³⁺, Cu^+/2+, Cd²⁺, Hg²⁺, In³⁺, Pb²⁺, Sb³⁺, Tl^+/3+, and Zn²⁺.

31. The mirror of claim 4, wherein the electrolytic solution is a solvent selected from the group consisting of benzonitrile, dimethylcarbonate, dimethylsulfoxide, ethylene carbonate, ethylene glycol, γ

-butyrolactone, glycerol, propylene carbonate, sulfolane, and tetraglyme.

32. The mirror of claim 4, wherein the electrolytic solution further comprises a complexing species for chemically stabilizing the electrodepositable metal ion in solution, thereby facilitating the electrodeposition of a substantially uniform layer of the metal on the first electrode.

33. The mirror of claim 32, wherein the complexing species is selected from the group consisting of aromatic and olefinic compounds, aromatic nitrites, benzonitrile, aromatic heterocyclic amines, aromatic heterocyclic sulfides, quinoline, sulfides, aliphatic amines, aromatic amines, organo-nitriles, organo-phosphines, organo-thiols, organo-sulfides, halide ions, pseudohalide ions, and polyhydric alcohols.

34. An electrochemical mirror for reversibly controlling the propagation of electromagnetic radiation, comprising:

a first substrate which is substantially transparent to the radiation;

a first electrode which is disposed on the first substrate and which is substantially transparent to the radiation;

a surface modification layer disposed on the first electrode;

a second substrate which is substantially transparent to the radiation;

a second electrode which is distributed in localized areas on the second substrate;

an electrolytic solution disposed between and in electrical contact with the first and second electrodes;

a plurality of ions of a metal capable of electrodeposition on the first and second electrodes, the ions being soluble in the electrolytic solution; and

a plurality of atoms of said metal deposited on either the first or the second electrode,

such that a negative electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the second electrode into the solution and to be electrodeposited from the solution onto the first electrode, the surface modification layer facilitating substantially uniform nucleation of the electrodeposited metal on the first electrode, and

such that a positive electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the first electrode and electrodeposited from the solution onto the second electrode,

the amount of deposited metal subsisting on the first electrode affecting the reflectivity of the mirror for the radiation.

35. An electrochemical mirror for reversibly controlling the propagation of electromagnetic radiation, comprising:

a first substrate which is substantially transparent to the radiation;

a first electrode which is disposed on the first substrate and which is substantially transparent to the radiation;

a surface modification layer disposed on the first electrode;

a second, electricially insulating substrate which is substantially transparent to the radiation;

a second, continuously electrically conducting electrode which is arranged in a mesh pattern on the second substrate;

an electrolytic solution disposed between and in electrical contact with the first and second electrodes;

a plurality of ions of a metal capable of electrodeposition on the first and second electrodes, the ions being soluble in the electrolytic solution; and

a plurality of atoms of said metal deposited on either the first or the second electrode,

such that a negative electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the second electrode into the solution and to be electrodeposited from the solution onto the first electrode, the surface modification layer facilitating substantially uniform nucleation of the electrodeposited metal on the first electrode, and

such that a positive electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the first electrode and electrodeposited from the solution onto the second electrode,

the amount of deposited metal subsisting on the first electrode affecting the reflectivity of the mirror for the radiation.

36. An electrochemical mirror for reversibly controlling the propagation of electromagnetic radiation, comprising:

a first substrate which is substantially transparent to the radiation;

a first electrode which is disposed on the first substrate and which is substantially transparent to the radiation;

a surface modification layer disposed on the first electrode;

a second, electrically conducting substrate which is substantially transparent to the radiation;

a second, electrically discontinuous electrode arranged in a dot matrix pattern on the second substrate and having a relatively low overvoltage for electrodeposition of the metal relative to the second substrate;

an electrolytic solution disposed between and in electrical contact with the first and second electrodes;

a plurality of ions of a metal capable of electrodeposition on the first and second electrodes, the ions being soluble in the electrolytic solution; and

a plurality of atoms of said metal deposited on either the first or the second electrode,

such that a negative electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the second electrode into the solution and to be electrodeposited from the solution onto the first electrode, the surface modification layer facilitating substantially uniform nucleation of the electrodeposited metal on the first electrode, and

such that a positive electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the first electrode and electrodeposited from the solution onto the second electrode,

the amount of deposited metal subsisting on the first electrode affecting the reflectivity of the mirror for the radiation.

37. An electrochemical mirror for reversibly controlling the propagation of electromagnetic radiation, comprising:

a first substrate which is substantially transparent to the radiation;

a first electrode which is disposed on the first substrate and which is substantially transparent to the radiation;

a surface modification layer disposed on the first electrode;

a second, electrically insulating substrate which is substantially transparent to the radiation;

a second electrode which is an electrically continuous grid of an electrochemically stable metal deposited on the second substrate;

an electrolytic solution disposed between and in electrical contact with the first and second electrodes;

a plurality of ions of a metal capable of electrodeposition on the first and second electrodes, the ions being soluble in the electrolytic solution; and

a plurality of atoms of said metal deposited on either the first or the second electrode,

such that a negative electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the second electrode into the solution and to be electrodeposited from the solution onto the first electrode, the surface modification layer facilitating substantially uniform nucleation of the electrodeposited metal on the first electrode, and

such that a positive electrical potential applied to the first electrode relative to the second electrode tends to cause deposited metal to be dissolved from the first electrode and electrodeposited from the solution onto the second electrode,

the amount of deposited metal subsisting on the first electrode affecting the reflectivity of the mirror for the radiation.