Single and double sided electrochromic displays

• US 5,877,888 A
• Filed: 06/10/1997
• Issued: 03/02/1999
• Est. Priority Date: 06/10/1997
• Status: Expired due to Fees

• Current Assignee: Monsanto Company (Bayer AG)
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: Coleman, James P.
• Primary Examiner(s): Epps, Georgia
• Assistant Examiner(s): BURKE, MARGARET A
• Application Number:
  US08/872,544
• Time in Patent Office: 630 Days
• Field of Search: 359/265, 359/266, 359/267, 359/268, 359/269, 359/271
• US Class Current: 359/267
• CPC Class Codes: G02F 1/133342 for double-sided displays
• 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 1/1533 structural features not otherwise provided for
• CPC Class Codes: G02F 1/155 Electrodes

Abstract

An electrochromic display device and method are disclosed. The device comprises an ionically isolative layer containing an electrochromic material in contact with an electrolyte layer and a working electrode. The working electrode is positioned on a first side of a substrate, while a counter electrode is positioned on an opposite side of the substrate. The counter electrode is electrically coupled to the electrolyte layer on the substrate first side through one or more openings extending through the substrate. In another embodiment, ionically isolative and electrolyte layers are also provided in contact with the counter electrode on the backside of the substrate to create a double sided display. The method comprises reversible electrochromic effects of the electrochromic materials contained in either the ionically isolative layers or the electrolyte layers.

Claims

1. A double-sided electrochromic display device, comprising:

a substrate having at least a first surface and a second surface;

an electrode assembly consisting essentially of a working electrode on the first surface of the substrate and a counter electrode on the second surface of the substrate;

a first ionically isolative, electrically conductive layer on and electrically coupled to the working electrode;

a first electrolyte layer over the first surface of the substrate covering the first ionically isolative, electrically conductive layer;

a second ionically isolative, electrically conductive layer on and electrically coupled to the counter electrode;

a second electrolyte layer over the second surface of the substrate covering the second ionically isolative, electrically conductive layer, and in ionic communication with the first electrolyte layer; and

an electrochemically active material disposed within the electrochromic display device so that, when an electric potential is applied between the working electrode and the counter electrode, a first electrochromic reaction occurs at an interface between the first electrolyte layer and the first ionically isolative, electrically conductive layer and a second electrochromic reaction occurs at an interface between the second electrolyte layer and the second ionically isolative, electrically conductive layer, the first electrochromic reaction resulting in a first color change and the second electrochromic reaction resulting in a second color change; and

one of the first electrochromic reaction and the second electrochromic reaction being an anodic reaction and the other being a cathodic reaction.

2. The device of claim 1, wherein the substrate is planar, and the first surface of the substrate and the second surface of the substrate are on opposite sides of the substrate.

3. The device of claim 2, wherein the ionic communication between the first and second electrolyte layers occurs through at least one hole in the substrate.

4. The device of claim 3, wherein the working electrode is formed in a first image defining pattern, and the counter electrode is formed in a second image defining pattern;

the first color change occurs in a region of the interface between the first electrolyte layer and the first ionically isolative, electrically conductive layer that is over the first image defining pattern; and

the second color change occurs in a region of the interface between the second electrolyte layer and the second ionically isolative, electrically conductive layer that is over the second image defining pattern.

5. The device of claim 3, wherein the first ionically isolative, electrically conducting layer contains a first electrochromic material.

6. The device of claim 5, wherein the second ionically isolative, electrically conducting layer contains a second electrochromic material.

7. The device of claim 6, wherein the first electrochromic material and the second electrochromic material are the same.

8. The device of claim 3, wherein the electrolyte contains a metal salt containing a reversibly precipitable metal, the metal depositing or dissolving in a pattern over the working electrode and the counter electrode depending upon a polarity of the working electrode relative to the counter electrode, the deposition thereby resulting in either the first color change or the second color change and the dissolving thereby resulting in the other color change, depending upon said polarity.

9. The device of claim 3, wherein the ionic communication occurs through a plurality of holes through a portion of substrate covered on opposite sides by the first and the second ionically conductive, electrically insulating layers, the plurality of holes extending through the first and the second ionically conductive, electrically insulating layers.

10. A method of operating a double-sided electrochromic display device containing electrochromic material and having an electrode assembly consisting essentially of a working electrode on a first side of a substrate and a counter electrode on a second side of the substrate, a first ionically isolative, electrically conductive layer covering the working electrode, a first electrolytic layer over the first ionically isolative, electrically conductive layer, and a second ionically isolative, electrically conductive layer covering the counter electrode, and a second electrolytic layer over the second ionically isolative, electrically conductive layer, wherein the first and second electrolytic layers are in ionic communication with one another, the method comprising the step of:

applying a voltage across the working and counter electrodes to change a color of electrochromic material at an interface between the first electrolytic layer and the first ionically isolative, electrically conductive layer and to change a color of electrochromic material at an interface between the second electrolytic layer and the second ionically isolative, electrically conductive layer, the electrochromic material at one of the interfaces undergoing an anodic electrochromic reaction and the electrochromic material at the other interface undergoing a cathodic electrochromic reaction.

11. The method of claim 10, further comprising the step of:

removing the applied voltage to reverse the changes in color at the respective interfaces.

12. The method of claim 10, wherein electrochromic material is contained within the first ionically isolative, electrically conductive layer and within the second ionically isolative, electrically conductive layer.

13. The method of claim 12, wherein the electrochromic material contained within the first ionically isolative, electrically conductive layer the electrochromic material contained within the second ionically isolative, electrically conductive layer are the same.

14. The method of claim 10, wherein a metal salt is dissolved in the first and the second electrolytic layers, and wherein the step of applying the voltage comprises the step of depositing metal from the metal salt at an interface of either the first or the second electrolytic layer and a region of the corresponding one of the first or the second ionically isolative, electrically conductive layer covering the working electrode or the counter electrode, respectively,

and further comprising the step of reversing the polarity of the applied voltage to redissolve the deposited metal and to deposit metal from the metal salt at the other interface.

15. A process for manufacturing a double-sided electrochromic display device, comprising the steps of:

positioning an electrode assembly consisting essentially of a working electrode on a first side of a substrate and a counter electrode on a second side of the substrate;

laminating a first ionically isolative, electrically conductive layer containing a first electrochromically active material over the working electrode and a second ionically isolative, electrically conductive layer containing a second electrochromically active material over the counter electrode;

laminating a first electrolyte layer over the first ionically isolative, electrically conductive layer and a second electrolyte layer over the second ionically isolative, electrically conductive layer; and

ionically coupling the first electrolyte layer to the second electrolyte layer through at least one opening in the substrate.

16. The process of claim 15, wherein the step of positioning includes forming the working electrode in a first image-defining pattern and the counter electrode into a second image-defining pattern.

17. The process of claim 16, further comprising the step of forming the at least one opening in the substrate through at least one of the first image-defining pattern and the second image-defining pattern.

18. A process for manufacturing a double-sided electrochromic display device, comprising the steps of:

positioning an electrode assembly consisting essentially of a working electrode on a first side of a substrate and a counter electrode on a second side of the substrate;

laminating a first ionically isolative, electrically conductive layer over the working electrode and a second ionically isolative, electrically conductive layer over the counter electrode;

laminating a first electrolyte layer over the first ionically isolative, electrically conductive layer and a second electrolyte layer over the second ionically isolative, electrically conductive layer; and

ionically coupling the first electrolyte layer to the second electrolyte layer through at least one opening in the substrate;

wherein the first electrolyte layer and the second electrolyte layer contain a dissolved salt of a reversibly precipitable metal that precipitates at either an interface of the first electrolyte layer and the first ionically isolative, electrically conductive layer or an interface of the second electrolyte layer and the second ionically isolative, electrically conductive layer, depending upon a polarity of the applied voltage.

19. The process of claim 18, wherein the step of positioning includes forming the working electrode in a first image-defining pattern and the counter electrode in a second image-defining pattern.

20. The process of claim 19, further comprising the step of forming the at least one opening in the substrate through at least one of the first image-defining