Electrochromic materials and displays

• US 5,500,759 A
• Filed: 08/25/1994
• Issued: 03/19/1996
• Est. Priority Date: 12/22/1992
• 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 Y.
• Assistant Examiner(s): Robbins, Thomas
• Application Number:
  US08/296,372
• Time in Patent Office: 572 Days
• Field of Search: 359/265, 359/269, 359/270
• US Class Current: 359/270
• CPC Class Codes: C09K 9/00 Tenebrescent materials, i.e. materials for which the range of wavelengths for energy absorption is changed as a result of excitation by some form of energy
• CPC Class Codes: C09K 9/02 Organic tenebrescent materials
• CPC Class Codes: G02F 1/15165 Polymers
• CPC Class Codes: G02F 1/1524 Transition metal compounds
• CPC Class Codes: G02F 1/1533 structural features not otherwise provided for
• CPC Class Codes: G02F 1/155 Electrodes
• CPC Class Codes: G02F 2001/1517 Cyano complex compounds, e.g. Prussian blue
• CPC Class Codes: G02F 2001/1557 Side by side arrangements of working and counter electrodes
• CPC Class Codes: G02F 2202/022 polymeric
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials
• CPC Class Codes: H01B 1/08 oxides
• CPC Class Codes: H01B 1/20 Conductive material dispersed in non-conductive organic material organic macromolecular compounds or compositions C08
• CPC Class Codes: H01B 1/22 the conductive material comprising metals or alloys
• CPC Class Codes: H01B 1/24 the conductive material comprising carbon-silicon compounds, carbon or silicon

Abstract

Dispersions of electrically conductive particles useful for preparing electrically conductive, essentially ionically isolative composite layers having electrically conductive particles dispersed in a polymer matrix. Composite layers can be used in laminates for electrochromic displays where an ionically conductive layer is in contact with electrochromic material. Such displays comprise means for applying an electrical potential across the interface of the ionically conductive layer and the electrochromic material to generate an electrochromic effect at the interface. Electrochromic materials can be provided in the laminates as layers between the ionically conductive layer and the composite layer of electrically conductive particles dispersed in a polymer matrix. Alternatively, the electrochromic material can be incorporated in the conductive particles in the polymer matrix, e.g. as titanium dioxide coated with antimony tin oxide coated with polyaniline dispersed in an light transmitting polymer matrix. The materials of this invention allow for the high speed fabrication of flexible displays, e.g. by printing methods.

Claims

1. A method of fabricating flexible electrochromic displays comprising an ionically conductive layer on an electrochromic layer, said method comprising printing an electrode pattern in contact with an electrically conductive, essentially ionically isolative composite layer of electroconductive particles dispersed in a polymer matrix.

2. An electrochromic display laminate comprising:

(a) a substrate coated in one or more areas with a layer of an electrically conductive material forming electrode areas on said substrate;

(b) an ionically isolative layer of an electrically conductive, essentially ionically isolative material on said electrode areas;

(c) a layer of ionically conductive material on said ionically isolative layer;

wherein electrochromic material is present at an interfacial zone between said ionically isolative layer and said ionically conductive layer, said electrochromic material being dispersed or dissolved in said ionically isolative material, in said ionically conductive material, in both of said ionically isolative and ionically conductive materials or is present in a separate layer in said interfacial zone; and

wherein said laminate has electrode areas adapted to provide an electrical potential across said interfacial zone to generate an electrochromic effect at said interfacial zone.

3. A laminate according to claim 2 wherein said electrochromic material comprises particles selected from the group consisting of:

(a) an electrically conductive core coated with electrochromic material,

(b) an electrochromic material core and an electrically conductive coating,

(c) electrically conductive electrochromic material, or

(d) agglomerations of electrochromic material and electrically conductive material.

4. A laminate according to claim 3 wherein said electrochromic material is selected from the group consisting of a polyaniline, a polypyrrole, a polythiophene, a polyvinylferrocene, a polyviologen, tungsten oxide, iridium oxide, molybdenum oxide, nickel oxide and Prussian blue.

5. A laminate according to claim 3 wherein said particles of electrochromic material are dispersed in the layer of one or more areas of an electrically conductive, essentially ionically isolative material.

6. A laminate according to claim 5 wherein said layer of one or more areas of an electrically conductive, essentially ionically isolative material comprises said particles of electrochromic material dispersed in a transparent or translucent polymer matrix.

7. A laminate according to claim 6 wherein said polymer matrix is an optically transparent or translucent clear thermoplastic polymer selected from the group consisting of a polystyrene, polyacrylate, polymethacrylate, polyurethane, polyolefin, polyester, polyamide, polycarbonate, polyvinyl halide, polyvinyl acetal, polyvinyl ester, polyvinyl alcohol, styreneacrylonitrile copolymer, acrylonitrile-butadiene-styrene graft copolymer or blends thereof or a elastomeric polymer selected from a group consisting of acrylate rubber, butadiene rubber, ethylene-propylene diene monomer rubber, ethylene-propylene rubber, styrene butadiene rubber and nitrile rubber or a thermoplastic elastomer comprising a blend of polypropylene and rubber.

8. A laminate according to claim 3 wherein said layer of ionically conductive material comprises a polymeric gel containing a hygroscopic material or a humectant.

9. A laminate according to claim 8 wherein said hygroscopic material which is a deliquescent material is selected from the group consisting of lithium bromide, calcium chloride, glycerins, sodium dihydrogen phosphate and lithium trifluoromethylsulfonate.

10. A laminate according to claim 2 wherein said electrodes comprise metal, metal oxide, carbon, intrinsically conducting polymer or polymer filled with conductive particles.

11. A laminate according to claim 2 wherein said electrical potential is applied by means of two or more electrodes in contact with separate areas of the layer of electrically conductive, essentially ionically isolative material and electrically joined by said material;

wherein the electrical resistance between said electrodes is lowest in a path running from said electrodes to said ionically isolative material connected through said layer of ionically conductive material.

12. A laminate according to claim 2 wherein the there is electrical conductivity between said areas of ionically isolative material such that the path of lowest electrical resistance between said areas is through said layer of ionically conductive material, whereby said electrochromic image is erasable by removal of the electrical potential that created said image and without external means of short circuiting the electrodes that created the image.

13. A laminate according to claim 2 further comprising an electrically-conductive, visible light-transmitting layer on said layer of ionically conductive material.

14. A laminate according to claim 2 wherein said layers are disposed on at least one side of a flexible substrate, whereby said laminate is flexible.