JPS61252536A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To obtain a display element which is stable, long in life and suitable for a thin type by providing a soln. or electrolyte packed between substrates and providing a high-polymer film having a redox active point on the surface of either display electrode or counter electrodes. CONSTITUTION:An ITO film is deposited by evaporation as the display electrode 2 on the glass substrate 1 and a WO3 film 3 is deposited by vacuum evaporation thereon in an amorphous state. On the other hand, the ITO film is deposited by vacuum evaporation on the glass substrate 4 and a thin polypyrrole film is provided by electrolytic polymn. thereon to form a functional high-polymer film 6. 1M LiCl4 and propylene carbonate electrolyte are packed as the electrolyte 7 between two sheets of such substrates and the substrates are sealed by a sealing part 8. The electrons and the cation in the electrolyte 7 are implanted to the WO3 film 3 and the film colors when a voltage is impressed between the display electrode 2 as negative electrode and the counter electrode 5. The electrons migrate at the same instant from the film 6 to the electrode 5 and the anion in the electrolyte 7 is implanted into the film 6. The thin type display element having the stability and long life is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrochromic (EC) display element that can be used as various display elements for watches, home appliances, guidance displays, information equipment, and the like.

BACKGROUND OF THE INVENTION In general, EC display elements include those represented by inorganic compounds such as W2B, and those represented by organic compounds such as styryl-like compounds and viologen derivatives. These ECs
The counter electrode of the display element is platinum, carbon, iron complex, WO2,
Engineering To etc. are used. It is desired that these counter electrode materials be capable of reversibly supplying the same amount of charge on the counter electrode side as the charge amount of the redox reaction on the display electrode side.

Problems to be Solved by the Invention However, conventionally used counter electrode materials mainly use redox reactions on the surface of the counter electrode, and therefore have apparently fewer redox active sites. Therefore, attempts have been made to solve this problem by increasing the area of the counter electrode to increase the amount of charge supplied, but increasing the area of the counter electrode increases the volume occupied by the counter electrode, which is not preferable for realizing a flat panel display element.

Furthermore, depending on the type of counter electrode material, such as ITO, reversibility is difficult to maintain, which poses a problem in terms of the lifespan of the display element.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrochromic display element that is stable, has a long life, and is suitable for being thin.

Means for Solving the Problems The present invention achieves the above object, and includes a display electrode provided on one of two substrates, at least one of which is transparent, and the other substrate opposite to the display electrode. An electrolyte comprising: a counter electrode provided on the display electrode; and a solution or electrolyte filled between the substrates; and a polymer film having a redox active site is provided on the surface of at least one of the display electrode or the counter electrode. A chromic display element is provided.

Function The present invention provides a polymer film with a high density of redox active sites on the surface of at least one of the display electrode and the counter electrode, so even a thin film can supply a sufficient amount of charge necessary for display. Stable and long life can be achieved.

The polymers having redox active sites of the present invention include ferrocene derivative polymers, polynitrostyrene, polyaniline, tetrathiafulvalene polymers, viologen derivative polymers, electropolymerized membranes such as polypyrrole and polythiophene, and metal complexes fixed thereon. Polymeric coordination compounds, e.g. Ru(edta)'Ru(NH3)6(H2O)
, Fe(CN)6(H2O).

Polyvinylpyridiy coordinate bonded with Cu2+ ion etc.
, puly-Ru(4-methyl-4'-viny#-2
゜2′-Bibirisif)”, puly-Fe(4-
Bipyridine polymers coordinately bonded with methyl-47-pinyl-2,2'-bipyridine and the like are suitable.

In addition, polymer electrolyte compounds in which multivalently charged metal complexes are fixed in the membrane by electrostatic bonding, such as Ir(J2ri3-
4-/S-Fs(ON)6.1vio(ON)8'-/'- and other protonated polyvinylpyridine with immobilized metal complexes, quaternized Q polyvinylpyridine, Ru(NH3)
e tRu (2y 2'-bipyridine)3'''
'/3+2+/3+ Polystyrene sulfonic acid with immobilized complex, Natio
Polymer electrolyte membranes such as N (trade name of DuPont) are also suitable. In order to attach these functional polymers with redox active sites to the counter electrode surface, there are adsorption methods in which they are dissolved in an appropriate organic solvent, coated, and dried, and covalent methods in which they are immobilized via amide, ether, or siloxane bonds, etc. −
e) Any method may be used, such as an electrolytic deposition method in which -r-4 is produced, or a gas deposition method in which heated evaporation or plasma polymerization reaction is used.

Example Embodiments of the present invention will be described below with reference to the drawings.

<Example 1> FIG. 1 is a sectional view of an electrochromic display element according to an example of the present invention, in which WO3 is used as the EC material. 1 is the glass or plastic substrate;
2 is a display electrode using a transparent conductive material such as ITO or tin oxide, 3 is an EC material with a WO3 thin film, 4 is a substrate made of glass or plastic, and 5 is a transparent conductive material such as ITO or tin oxide, or metal is used. A counter electrode, 6 is a functional polymer membrane having redox active sites, 7 is an electrolytic solution, and 8 is a sealing part.

Such a device is manufactured as follows.

First, an ITO film is deposited as a display electrode 2 on a glass substrate 1, and a WO3 film 3 is vacuum deposited thereon in an amorphous state. On the other hand, the ITO membrane is vacuumed as the opposite policy 4 on the glass substrate 4, and on it, 0.1m Pylol, 0. IMEt4N
PF6. Approximately 300 polypyrrole thin films are applied by electrolytic polymerization in an acetonitrile electrolyte to form a functional polymer film 6. Between these two substrates, 1 MLi (JO
4. Fill with propylene carbonate electrolyte and seal with a sealing part 8 made of epoxy resin. Regarding the EC display element made in this way, the display electrode 2 is made negative and the voltage (
When 1,3 V) is applied between t and the counter electrode 6, electrons and cations in the electrolytic solution 7, such as Li+, are injected into the WO3 film 3, causing color development. At the same time, electrons move from the functional polymer membrane 6 to the counter electrode 6, and the anions in the electrolyte 7, for example, C1o
4- is injected into the functional polymer film 6. If the polarity of the applied voltage is reversed, the opposite will occur.9W03 The film 3 will be decolored. The EC display element of the present invention operates in this way, but as mentioned above, the density of redox active sites in the functional polymer is high, so even a thin film can supply the amount of charge necessary for display. A thin flat panel display element with a spacing of 20 μm was obtained.

Now, if the counter electrode is metal or the functional polymer is colored, a white reflective plate or film may be inserted between the WO3 film 3 and the functional polymer film 6, but the operation of the present invention Since this is unrelated to the principle, the description of FIG. 1 will be omitted. In addition, we have taken up WO3 film as an EC material, but
This is just an example; other materials such as MoO3, iridium oxide, etc. may also be used, and even if organic substances such as viologen derivatives are used, the operation will not change in any way.

<Example 2> Next, the EC material is represented by the molecular structure of formula (1).

When a styryl-like compound is used, this EC material is dissolved in the electrolytic solution 9, resulting in the EC surface element structure shown in FIG. The difference from Figure 1 is that there is no WO3 film in 3, and the electrolyte 9 is o, 1M styryl-like compound 1 and 1MTB.
It consists of AP and propylene carbonate. This EC display element developed a red color when a voltage of 1.3 V was applied between the display electrode 2 and the counter electrode 6 so that the display electrode 2 was positive, and the color disappeared when the polarity of the voltage was reversed. In this case as well, the same functional polymer 6 as in the previous example was used, so that a thin flat plate type EC display element was produced.

<Example 3> Polystyrene sulfonic acid was used as a counter electrode polymeric functional membrane.
A fixed u(2,2'-bipyridine)3 complex was used and applied onto an ITO transparent electrode.

Using this as a counter electrode, a display element as shown in FIG. 2 was fabricated. When the solution used in Example 2 was injected into this and a voltage was applied so that the display electrode side became positive, the color developed into red. When the polarity of voltage application was reversed, the color disappeared.

<Example 4> A polythiophene film was formed on ITO to a thickness of 0.6 μm by electrolytic polymerization as a counter electrode, and then a display element as shown in FIG. 2 was produced. ITO was used as the display electrode. When the solution used in Example 2 was injected into the inside of this element, a phenomenon of color development and fading was observed upon application of voltage, as shown in the appendix. In addition, compared to when the counter electrode is only ITO, the influence of the area ratio of the display electrode and the counter electrode is small, and the color development characteristics are also 2.
I found it to be more than twice as good.

In the above embodiments, the basics of operation have been shown using typical materials, but an EC display element with exactly the same operating principle can be obtained even if the above-mentioned materials are used in each product. Such an EC display element can be made thin, and since the redox reaction is reversible, a stable and long-life display element is possible.

Furthermore, as shown in Fig. 1, the electrolyte can be eliminated in a state where it is contained in the functional polymer membrane, and in this case, the electrolyte is contained in a semi-solid EC.
A display element is made. Furthermore, the electrolyte shown in FIG. 1 can also be operated in a gelled state.

Effects of the Invention In short, the present invention provides an electrochromic display element in which a polymer film having redox active sites is provided on the surface of at least one of a display electrode and a counter electrode, which are provided facing each other, and is stable and long-lasting. This has the advantage that a thin display element with a long life can be achieved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an electrochromic display element according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of an electrochromic display element according to another embodiment of the present invention. 1.4...Substrate, 2...Display electrode, 6.
...Counter electrode, 6...Polymer membrane, 7,9...
... Electrolyte, 8 ... Sealing part.

Claims (1)

[Claims] a display electrode provided on one of two substrates, at least one of which is transparent; a counter electrode provided on the other substrate opposite to the display electrode; and a solution or electrolyte filled between the substrates. An electrochromic display element comprising: a polymer film having redox active sites on the surface of at least one of the display electrode or the counter electrode.