Electrochromic layer and devices comprising same

Details Electrochromic layer and devices comprising same Electrochromic layer and devices comprising same

1999-07-27

2001-06-19

Tucker, Philip (Department: 1712)

Compositions

Light transmission modifying compositions

Modification caused by energy other than light

C359S265000, C359S267000, C359S273000, C359S275000

Reexamination Certificate

active

06248263

ABSTRACT:

TECHNICAL FIELD
The present invention relates to electrochromic devices which provide light-filtering, color-modulation, or reflectance-modulation in apparatus such as variable-transmittance windows, variable-reflectance mirrors; and display devices which employ such light-filters or mirrors in conveying information.
More particularly, the invention concerns the electrochromic medium in such an electrochromic device. The electrochromic medium undergoes a change in transmittance to light, and a concomitant change in color, when an electrical potential difference is imposed across it in the device.
The invention relates to novel electrochromic media which address a number of problems presented by electrochromic devices with electrochromic media which comprise fluids or solutions. The media of the invention occur in electrochromic devices of the invention as electrochromic layers occupying the space between electrode layers of the devices. A medium of the invention comprises a polymeric matrix, which provides a measure of structural integrity and other advantages, and an electrochromic solution, which is interspersed throughout the polymeric matrix and provides variable transmittance to light.
In addition to the novel electrochromic media and electrochromic devices of the invention, the invention relates to novel apparatus which comprise the electrochromic devices of the invention to provide light-filtering or color-modulation.
BACKGROUND OF THE INVENTION
The term electrochromic is broad and encompasses within it various media, such as, for example, solution-phase, surface-confined, electro-deposition, or combinations thereof, which undergo a change in transmittance to light, and a concomitant change in color, when an electrical potential difference is imposed across the electrochromic media in a device.
There has been a great deal of research on surface-confined electrochromic media where the layers changing their transmittance to light are thin films deposited on the transparent electrodes within an electrochromic device. In these devices, an anodic electrochromic layer and a cathodic electrochromic layer are separate and distinct, and are electrically connected by a conductive electrolyte. Either thin film may be stoichiometric and nonstoichiometric forms of transition metal oxides, such as for example tungsten oxide, molybdenum oxide, nickel oxide, rhodium oxide, iridium oxide, niobium oxide, vanadium oxide, titanium dioxide, and combinations thereof. These electrochromic solid films are typically paired with an auxiliary redox system, which may be another metal oxide, or may be a solution phase, a surface-confined polymer film, or an electro-deposited polymer film species (all of which are described in detail hereinbelow).
These surface-confined thin films may also be a polymeric layer such as polyanaline, polypyrroles, polythiophenes, and the like. U.S. Pat. No. 5,282,955, entitled “Electrically Conductive Polymer Composition, Method of Making Same and Device Incorporating Same” to N. Leventis et al. teaches an electrically conductive polymer with a porous structure having an electrochromic compound coated on the surfaces of the pores of the structure.
The electrochromic media may comprise an electro-deposition-type materials such as, for example, metal, metal oxides and heptyl viologen bromide in water.
Finally, the electrochromic media may include a solution-phase system. Solution-phase electrochromic devices and various circuitry and applications thereof are described in U.S. Pat. No. 4,902,108, entitled “Single-Compartment, Self-Erasing, Solution-Phase Electro-optic Devices Solutions for Use Therein, and Uses Thereof”, issued Feb. 20, 1990 to H. J. Byker; Canadian Patent No. 1,300,945, entitled “Automatic Rearview Mirror System for Automotive Vehicles”, issued May 5, 1992 to J. H. Bechtel et al.; U.S. Pat. No. 5,128,799, entitled “Variable Reflectance Motor Vehicle Mirror”, issued Jul. 7, 1992 to H. J. Byker; U.S. Pat. No. 5,202,787, entitled “Electro-Optic Device”, issued Apr. 13, 1993 to H. J. Byker et al.; U.S. Pat. No. 5,204,778, entitled “Control System For Automatic Rearview Mirrors”, issued Apr. 20, 1993 to J. H. Bechtel; U.S. Pat. No. 5,278,693, entitled “Tinted Solution-Phase Electrochromic Mirrors”, issued Jan. 11, 1994 to D. A. Theiste et al.; U.S. Pat. No. 5,280,380, entitled “UV-Stabilized Compositions and Methods”, issued Jan. 18, 1994 to H. J. Byker; U.S. Pat. No. 5,282,077, entitled “Variable Reflectance Mirror”, issued Jan. 25, 1994 to H. J. Byker; U.S. Pat. No. 5,282,077, entitled “Variable Reflectance Mirror”, issued Jan. 25, 1994 to H. J. Byker; U.S. Pat. No. 5,294,376, entitled “Bipyridinium Salt Solutions”, issued Mar. 15, 1994 to H. J. Byker; U.S. Pat. No. 5,336,448, entitled “Electrochromic Devices with Bipyridinium Salt Solutions”, issued Aug. 9, 1994 to H. J. Byker; U.S. Pat. No. 5,434,407, entitled “Automatic Rearview Mirror Incorporating Light Pipe”, issued Jan. 18, 1995 to F. T. Bauer et al.; U.S. Pat. No. 5,448,397, entitled “Outside Automatic Rearview Mirror for Automotive Vehicles”, issued Sep. 5, 1995 to W. L. Tonar; and U.S. Pat. No. 5,451,822, entitled “Electronic Control System”, issued Sep. 19, 1995 to J. H. Bechtel et al. Each of these patents is commonly assigned with the present invention and the disclosures of each, including the references contained therein, are hereby incorporated herein in their entirety by reference. Additionally, the following references by others are also incorporated herein in their entirety by reference: U.S. Pat. Nos. 3,806,229 and 3,451,741; European Patent Application Publication Nos. 0 012 419, 0 430 684, 0 430 686, 0 435 689 and 0 552 012; and Non-emissive Electrooptic Displays, Kmetz and von Willisen, eds., Plenum Press, New York, N.Y., USA (1976), and especially the chapter therein by Chang, “Electrochromic and Electrochemichromic Materials and Phenomena,” at pp. 155-196.
In typical solution-phase electrochromic devices, and particularly devices which are single-compartment and self-erasing, a solution is held as a thin layer in a compartment which is formed by two walls, at least one of which is transparent to light (electromagnetic radiation of wavelength in the visible range), and spacers or sealant which separate the two walls and form the periphery of the compartment. The inner sides, those which face each other, of the two walls are each coated with an electrode layer which is in contact with the solution. An electrode layer functions as an electrode in contact with the solution and is a layer of a material which is electronically conducting. The electrode layer on at least one of the walls is transparent to light, because, as indicated above, at least one of the walls is transparent to light. Transparent electrode layers may be made of tin oxide, tin-doped indium oxide, indium tin oxide, fluorine-doped tin oxide, fluorine-doped zinc oxide, gold, cadmium stannate, ruthenium oxide, or the like, as known in the art. One of the walls and, consequently, one of the electrode layers may be non-transparent. For example, a non-transparent electrode layer might be a reflecting layer, a layer which reflects light, and may be made of a metal, semiconductor material, or the like which may or may not be specularly reflecting.
The layer of solution or other type of medium between the walls of an electrochromic device is sometimes referred to as an “electrochromic layer.”
When a sufficient potential difference is applied between the electrode layers across the solution of such a device, the transmittance of the solution changes at least one wavelength in the visible range and, as a consequence, the solution changes color, becoming darker or clearer. Typically, the solution in such a device will be clear or slightly colored (tinted) in its zero-potential, equilibrium state and will be darkened through electrochemical reaction(s) when a potential difference is applied. If the device is a solution-phase electrochromic device, the electrochromic compounds (those which have a change in transmittance in the visi

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