Electrochromic element

Details Electrochromic element Electrochromic element

2000-06-07

2001-03-20

Epps, Georgia (Department: 2873)

C359S265000, C359S267000, C359S268000

Reexamination Certificate

active

06203154

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to electrochromic elements and more particularly electrochromic elements which are useful as light controllable windows for buildings, automobiles and passenger vehicles and various types of light controllable glasses to be used for indoor decoration or partitions; display devices; and anti-dazzle mirrors for automobiles and other vehicles.
2. Description of the Prior Art
A conventional electrochromic device such as a light controllable glass of conventional type as disclosed in Japanese Patent Laid-Open Publication No. 63-18336 is known which glass 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.
3 . Problems to be solved
However, the conventional film formation techniques must be carried out under vacuum, resulting in increased production costs and a requirement of a large size vacuum apparatus if an electrochromic element of a large area is intended to be produced. Furthermore, since a substrate is heated at an elevated temperature during sputtering, it is necessary to select certain conditions if a substrate other than a glass, such as synthetic resin-made substrate is used, resulting in difficulties in lightening an electrochromic element.
There is also a problem that tungsten oxide can only make an electrochromic element exhibit blue color.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electrochromic element which can be manufactured using an inexpensive color developing material with easy operations and can easily be changed in color tone.
An electrochromic device proposed by the present invention solves the above-mentioned problems of the prior art by forming an electrochromic layer from a specific type of electrically conductive polymeric compound and presenting an electrochromic compound in an ion conductive material layer as well.
Namely, according to the present invention, there is provided an electrochromic element comprising two conductive substrates, at least one of which is transparent; an ion conductive layer disposed therebetween and containing a compound having a viologen structure represented by formula (1) below; and an electrochromic layer disposed between the ion conductive layer and at least either one of the two conductive substrates and containing a compound represented by formula (2) or (3) below; formula (1) being represented by
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
−
;
formula (2) being represented by
wherein R
1
is hydrogen or an alkyl group having 1 to 5 carbon atoms, R
2
, R
3
, R
4
and R
5
are each independently a hydrocarbon group or hydrocarbon residue having 1 to 20 carbon atoms and may be the same or different from each other, Ar
1
and Ar
2
are each independently a divalent aromatic hydrocarbon residue having 6 to 20 carbon atoms, a is an integer of greater than 2 and b and c are each an integer of 0 to 3; and
formula (3) being represented by
wherein R
6
, R
7
, R
8
, R
9
and R
10
are each independently hydrogen or a hydrocarbon group residue having 1 to 20 carbon atoms, Ar
4
and Ar
5
are each independently a divalent aromatic hydrocarbon residue, a′ is an integer of 0 to 3, b′ is an integer of 1 or 2 and c′ is an integer greater than 2.
DETAILED DESCRIPTION OF THE INVENTION
Two electrically conductive substrates, at least one of which is transparent, are used in the present invention. The conductive substrates may be any type of substrates as long as they have a function as an electrode. More specifically, the conductive substrate may be entirely formed from an electrically conductive material or formed with a non-electrically conductive substrate and an electrode layer disposed thereon. Regardless of whether a substrate is electrically conductive or not, it necessarily has a smooth surface at normal temperature but may have a flat or curved surface and may be deformable under stress.
At least of one of the two electrically conductive substrates is a transparent electrically conductive substrate and the other may be a transparent or opaque or reflective electrically conductive substrate.
Two conductive substrates both of which are transparent are suitable for a display device and a light controllable glass. A combination of a transparent conductive substrate and an opaque conductive substrate is suitable for a display device, while a combination of a transparent conductive substrate and a reflective substrate is suitable for an electrochromic mirror.
The transparent conductive substrate is generally formed by laminating a transparent electrode layer over a transparent substrate. The term “transparency” used herein designates an optical transmission ranging from 10 to 100 percent.
The opaque conductive substrate is may be a laminate obtained by laminating an electrode layer over one surface of a metal plate or a non-conductive opaque substrate such as various opaque plastics, ceramics, glasses, woods and stones.
The reflective electrically conductive substrate may be exemplified by (1) a laminate comprising a non-conductive transparent or opaque substrate and a reflective electrode layer formed thereon, (2) a laminate comprising a no-conductive transparent 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 non-conductive transparent substrate having a reflective layer formed thereon and further a transparent electrode layer formed thereon, (4) a laminate comprising a reflective substrate and a transparent electrode layer formed thereon and (5) a plate-like substrate which itself functions as a reflective layer and an electrode.
No particular limitations is imposed on the transparent substrate which 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 substrates used in the present invention must 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 film such as thin films of metals such as gold, silver, chrome, copper and tungsten or 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 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 are a metal such as copper, silver, gold, platinum, iron, tungsten, titanium and lithium, an

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