Electrochromic device

Details Electrochromic device Electrochromic device

2000-05-02

2002-08-20

Lester, Evelyn A. (Department: 2813)

Optical: systems and elements

Optical modulator

Light wave temporal modulation

C359S265000, C359S268000, C359S272000, C359S273000, C359S274000, C252S586000

Reexamination Certificate

active

06437901

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to electrochromic devices and more particularly electrochromic mirrors which are useful as light controllable elements such as light controllable windows (smart windows) for buildings, automobiles and passenger vehicles and various types of light controllable glasses for indoor decoration or partitions; display devices; antidazzle mirrors for automobiles; and decoration mirrors for indoor use.
DESCRIPTION OF THE PRIOR ART
A conventional electrochromic device such as a conventional type of antidazzle mirror as disclosed in Japanese Patent Laid-Open Publication No. 63-18336 is known which mirror comprises a chromogenic material in the form of a film obtained by sputtering or vacuum-depositing an inorganic oxide such as tungsten oxide (WO
3
) over a transparent electrically conductive film.
PROBLEMS TO BE SOLVED
Such an electrochromic antidazzle mirror is manufacture by a film forming operation carried out under vacuum conditions, resulting in increased production cost. A demand has therefore been placed on an electrochromic mirror which can be manufactured with inexpensive materials and by a simple and easy method.
A method has also been proposed in which to use a viologen compound as a component constituting an electrochromic device. However, further improvements on this method are demanded because the purification of viologen requires time and effort and the life or duration of coloration or decoloration functions of the device may be shortened, resulting from impurities such as an acid even in small amounts mixed into the system of the device.
DETAILED DESCRIPTION OF THE INVENTION
It is an object of the present invention to solve the aforementioned problems by using specific electrically conductive high molecular compounds as a color developing film or layer.
According to the present invention, there is provided an electrochromic device comprising two conductive substrates, at least one of which is transparent, an ion conductive layer disposed therebetween and an electrochromic color developing layer disposed between the ion conductive layer and at least either one of the two conductive substrates and containing (A) a compound having a viologen structure represented by the formula
wherein X
−
and Y
−
may be the same or different and each are a counter anion selected from the group consisting of a halogen anion, ClO
4
−
, BF
4
−
, PF
6
−
, CH
3
COO
−
and CH
3
(C
6
H
4
)SO
3
−
and (B) 4,4′-dipyridyl and/or a mono-substituted 4,4′-dipyridinium salt represented by the formula
wherein X
−
is a counter anion selected from the group consisting of a halogen anion, ClO
4
−
, BF
4−
, PF
6
−
, CH
3
COO
−
and CH
3
(C
6
H
4
)SO
3
−
.
According, to another aspect of the present invention, there is provided an electrochromic device all of which components are solid.
According to further another embodiment of the present invention, there is provided an electrochromic mirror which comprises a reflective conductive substrate, a transparent substrate, an ion conductive layer disposed therebetween and an electrochromic color developing layer disposed between the ion conductive and the reflective conductive substrate or transparent substrate.
The two conductive substrates, at least one of which is transparent, are used in the present invention. These substrates may be any type of substrates as long as they function as an electrode. More specifically, each of the conductive substrate may be those entirely formed from an electrically conductive material or those comprised of a non-electrically conductive substrate and an electrode layer disposed thereon. An electrochromic mirror according to the present invention includes a pair of such electrically conductive substrates, at least one of which is transparent and the other of which is reflective of light or non-reflective opaque. These transparent, reflective and opaque substrates may have a flat or curved surface and may be deformable under stress.
The transparent conductive substrate may generally exemplified by a laminate comprising a transparent substrate and a transparent electrode layer formed thereon. The reflective electrically conductive substrate may be exemplified by (1) a laminate comprising a transparent or opaque substrate and a reflective electrode layer formed thereon, (2) a laminate comprising a substrate having a transparent electrode layer on one of its surfaces and a reflective electrode layer on the other surface, (3) a laminate comprising a transparent substrate having a reflective layer formed thereon and further a transparent electrode layer formed thereon and (4) a plate-like substrate which itself functions as a reflective layer and an electrode. The non-reflective opaque conductive substrate is exemplified by a substrate selected from various metal plates or a laminate comprising a non-conductive opaque substrate such as various opaque plastics, ceramics, glasses and woods and an electrode formed on its surface.
No particular limitations is imposed on the transparent substrate. It may thus be a color or colorless glass, a reinforced glass and a resin of color or colorless transparency. Specific examples of such a resin include polyethylene terephthalate, polyamide, polysulfone, polyether sulfone, polyether etherketone, polyphenylene sulfide, polycarbonate, polyimide, polymethyl methacrylate and polystyrene.
The term “transparency” used herein designates an optical transmission which is in the range from 10 to 100 percent. The substrates used for the invention have a smooth surface at normal temperature.
There is no particular restriction to the transparent electrode layer as long as it meets the requirements for achieving the purpose of the present invention. Specific examples of the electrode layer include electrically conductive films such as thin films of various types of metals such as gold, silver, chrome, copper and tungsten or of metal oxides such as ITO (In
2
O
3
—SnO
2
), tin oxide, silver oxide, zinc oxide and vanadium oxide.
The electrode has a film thickness in the range of usually 100 to 5,000 and preferably 500 to 3,000 angstrom. The surface resistance of the electrode is usually in the range of 0.5-500 and preferably 1-50 &OHgr;/sq.
No particular limitation is imposed on a method of forming the electrode layer. Any suitable conventional methods may be employed, depending upon the kind of metal and metal oxide constituting the electrode. In general, the formation of the electrode layer is carried out by vacuum evaporation, ion plating, sputtering and a sol-gel method. The thickness of the electrode layer is selected within the range such that the transparency thereof is not affected. The electrode layer may be partially provided with an opaque electrode-activator for the purpose of imparting oxidation-reduction capability, electric conductivity and electric double layer capacitance, the electrode-activator being provided in an amount such that the transparency of the entire electrode layer is not harmed. Electrode activators eligible for the purpose of the invention arc metals such as copper, silver, gold, platinum, iron, tungsten, titanium and lithium, organic materials having oxidation-reduction capability such as polyaniline, polythiophen, polypyrrole and phthalocyanine, carbon materials such as active carbon and graphite and metal oxides such as V
2
O
5
, WO
3
, MnO
2
, NiO and Ir
2
O
3
and mixtures thereof. A variety of resins may be used for integrating the electrode activator in the electrode. The opaque electrode activator may applied onto an electrode by forming on an ITO transparent electrode a composition comprising an active carbon fiber, graphite and an acrylic resin into a micro pattern in the shape of stripes or by forming on a thin-film of gold a composition comprising V
2
O
5
, acetylene black and butyl rubber in the shape of a mesh.
No particular limitation is imposed on the reflective electrode layer as long as it is electrochemically stable and h

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