JPH0145895B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrochromic display device (hereinafter referred to as ECD), and particularly to an all-solid-state ECD.

ECD is a substance that is easily oxidized or reduced when electricity is applied, and that causes a large change in the absorption spectrum in the visible region (hereinafter such substances are referred to as electrochromic materials).
This refers to a display device that uses EC material (abbreviated as EC material) as a display material. Conventionally known types of ECD include solution type, precipitation type, and fixed type. The basic structures of the solution type and precipitation type are shown in Figure 1. A display substrate in which a display electrode 2 of a transparent electrode is formed on a transparent substrate 1 and a substrate 3 are interposed with a spacer 6 to form a cell. In addition to the display electrode 2, a counter electrode 4 is required, which is placed on the transparent substrate 1 or on the substrate 3.
A reference electrode 7 is also provided at an appropriate location as required. In a cell like this,
An electrolytic solution 5 containing an EC material is injected to form an ECD. In the solution type, when a positive or negative voltage is applied to the display electrode 2, the EC material is colored and displayed. When a voltage opposite to that shown is applied, the EC material returns to its original state and disappears. However, once the colored EC material separates from the electrode and diffuses into the interior, it will not fade even when a reverse voltage is applied, so it is necessary to mix white powder into the solution or add a porous white diffused reflector to both substrates. 1,3
Although the color is prevented from remaining by putting it in between, etc., it does not completely erase the color. The precipitation type uses an EC material that precipitates on the electrode when it is oxidized or reduced, and although it eliminates the problem of the EC material remaining undisappeared due to diffusion like the solution type, there is a risk of deterioration due to the deterioration of the precipitated material. However, there are problems in that the precipitates do not dissolve even if a reverse voltage is applied.

The EC materials used in the solution type are inorganic materials such as transition metal compounds such as tungstates and molybdates such as Na ₂ WO ₄ , CaWO ₄ , BaWO ₄ , Na ₂ M ₀ O _{4 ,} etc., and organic materials such as tungstates and molybdates. Substances include aromatic and heterocyclic compounds such as viologen, tetrathiafulvalene, allyl pyrazoline, fluorene, anthraquinone, pyrylium, pyridium, methylene blue, their derivatives, and coordination compounds of metals and organic substances such as ferroinferrocene. It is. The EC material used in the precipitation type is mainly viologen. Viologen becomes a precipitate type in an electrolytic solution using water as a solvent, but becomes a solution type in an electrolytic solution using an organic solvent.

The basic structure of the fixed type is shown in Figure 2. A display substrate having a transparent display electrode 2 and an electrochromic layer 8 formed on a transparent substrate 1 and a counter substrate having a counter electrode 4 formed on a substrate 3 are constructed with a spacer 6 in between. The electrolytic layer 5 between the substrates is an electrolytic solution or a solid electrolyte. Electrochromic layer 8
is tungsten oxide WO ₃ or molybdenum oxide MO ₃
or a coordination compound such as a rare earth metal-diphthalocyanine chain.

Until now, research has mainly focused on ECDs that use liquids, such as solution types and precipitation types, including fixed types that use electrolytic flow. There are dangers such as this, and there are essential drawbacks such as damage to other electronic components in the event of liquid leakage.

On the other hand, the fixed type using solid electrolyte is SiO,
Types that generate hydrogen ions by decomposing moisture adsorbed in the insulating layer, such as CaF ₂ and MgF ₂ , and Li ₃ N,
It is broadly classified into solid electrolytes such as β-Al ₂ O ₃ that conduct Li ⁺ or Na ⁺ ions. The former depends on the unstable state of adsorbed water, so the characteristics of the ECD are affected by the surrounding environment, and bubbles are generated due to water decomposition, but it is extremely unreliable. The latter has drawbacks such as slow response, easy reaction at the interface between the EC layer and solid electrolyte layer, and short life.

In addition to the above ECD types, phosphotungstic acid
ECD using H ₃ PO ₄ .(WO ₃ ) ₁₂ .nH ₂ O (hereinafter abbreviated as PWA) is known. The structure of this ECD is shown in Figure 3. PWA powder is pressed through a ceramic cylinder 11 onto the display electrode 2 formed on the transparent substrate 1 to form a PWA layer 9, and a graphite rod 4 is crimped onto this to form a counter electrode, and the periphery is covered with epoxy resin 10. It is an unfinished ECD that is still in the laboratory stage.
The transparent electrode is colored blue by applying a voltage of -1.0V for 25 msec, and shows a fast response for an ECD, reaching a white contrast of 2:1. but,
ECD using this PWA can (1) only emit blue; That is, there is no possibility of multicoloring. (2) Since the water contained in PWA is essentially involved in coloring and decoloring, the performance of ECD is easily influenced by the surrounding environment.
Also, it deteriorates quickly. (3) PWA is molded by pressing, but when molding by pressing, it is not possible to make sufficient contact with the transparent electrode and graphite, resulting in variations in properties and causing initial deterioration. Moreover, it is almost impossible to manufacture a practical device using such a press molding method, and even if it were possible, the cost would be high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a practical all-solid-state electrochromic display device that can display multiple colors, has fast response, high environmental resistance, long life, and low cost.

According to the present invention, a colored active material layer is a layer in which at least one electrochromic material and one or more ion transfer materials are dispersed in a polar polymer (hereinafter referred to as a polar polymer); An all-solid-state electrochromic display device having a structure in which a display electrode is formed on one side and a counter electrode is formed on the other side is obtained.

In the present invention having the above-described structure, the distance between the electrochromic material and the ion exchange material is extremely short, so that the response time during coloring and decoloring is extremely short compared to the conventional one. Furthermore, since a polymer is used, it has excellent moldability and processability, and can provide a practical ECD. Furthermore, since a polar polymer is used, the ion exchange material contained therein easily dissociates due to its polarity.
Shows high ionic conductivity. Therefore, high performance
ECD can be realized.

The structure of the ECD of the present invention is shown in FIG. As described above, the display electrode 2, the colored active material layer, and the counter electrode 4 are sequentially laminated on the transparent substrate 1, and the seal layer 10 covers the entire structure from above. Each component will be explained below. A transparent material such as glass or a plastic plate is used for the transparent substrate, and a transparent conductor such as a tin oxide (SnO ₂ ) film or an indium tin oxide (ITO) film is used for the transparent electrode. Transparent electrodes are usually formed by vacuum deposition, but chemical methods are also used.

The colored active material layer is made by dispersing one or more EC materials and one or more ion transfer materials in a synthetic polymer. As this EC material, all the EC materials that can be used in the solution type mentioned above can be used. For example, inorganic substances include Na ₂ WO ₄ ,
Transition metal compounds such as tungstates and molybdates such as CaWO ₄ , BaWO ₄ , Na ₂ MoO ₄ and organic substances such as viologen, tetrathiafulvalene, allylpyrazoline, fluorene, anthraquinone, pyrylium, pyridium, methylene blue, etc. Aromatic compounds, heterocyclic compounds, derivatives thereof, and coordination compounds of metals and organic substances such as ferroin and ferrocene. Next, the ion exchange material used here refers to a substance that can exchange ions with the above-mentioned EC material, such as a normal ion conductor,
It also includes not only ionic conductors but also those with low conductivity that cannot be used as solid electrolytes. For example, crown ether, its metal chain lithium nitride, and alkali metal perchlorate can be used as the ion transfer material. As the polar polymer, for example, polyvinylidene fluoride, polymethacrylonitrile, and derivatives thereof can be used.

The counter electrode includes gold (Au), silver (Ag), copper (Cu), and carbon (C).
Any conductive material can be used. Finally, for the sealing material, any material that has a sealing effect can be used, such as organic adhesives such as epoxy resin, low-melting glass, and IC molding materials.

Next, the present invention will be explained by an example (using FIG. 4).
explain. In the text, "parts" indicate parts by weight.

Example 1 By vacuum evaporation method on transparent glass substrate 1
An In ₂ O ₃ transparent electrode was provided as the display electrode 2. A colored active material layer 1 is formed on the display electrode 2 based on the following formulation.
2 was established.

1,1'-dialkyl-4,4'-dipyridium dichloride (this is commonly abbreviated as methyl viologen) 23 parts dibenzo-18-crown-6-lithium chloride 30 parts polyvinylidene fluoride 10 100 parts dimethyl formamide (DMF) The above composition is kneaded for 5 hours in a porcelain ball mill to obtain a colored active material composition. In this example, viologen, which develops color upon reduction, is used as the EC material.
A crown ether/metal salt chain was used as the ion transfer body. This composition was spin-coated on the transparent electrode 2 to a thickness of 1μ, and placed in an oven uniformly heated to 130°C in a nitrogen atmosphere.
The colored active material layer 12 was obtained by drying for a while.
On this colored active material layer 12, gold was vacuum-deposited to a thickness of 3000 Å to form a counter electrode 4. Furthermore, the periphery of the above laminated structure is covered with a sealing layer 1 of epoxy resin, alkyl resin, etc.
By covering it with 0, a durable ECD was created.

In the ECD thus manufactured, when a negative voltage was applied to the display electrode 2 with respect to the counter electrode 4, the colored active material layer 12 was colored deep blue, and when a positive voltage was applied, the color disappeared. Practically speaking, −2V
With the applied voltage, the contrast of white light became 4:1 in about 50 msec, and a display with good contrast of deep blue against a gold background was obtained. Next, when a voltage of +2V of opposite polarity was applied, the color completely disappeared in about 200 msec. Furthermore, -2V for 50msec, +2V
When a life test was performed by applying a pulse voltage of 200 msec, no deterioration phenomenon was observed in the colored active material layer 12 or its interface even after ¹⁰⁶ times of coloring and decoloring, and stable operation could be achieved over a long period of time. We were able to fabricate a practical all-solid-state ECD.

Example 2 In the manufacturing method described in Example 1, finely ground titanium oxide powder was added to the colored active material composition of this manufacturing method.
An ECD was produced using the same method as in Example 1, except that 22 parts of TiO ₂ was added to the colored active material composition.

The ECD in this example is white in the decolorized state and +2V
By applying , a dark blue display on a white background with a white light contrast of 4:1 was obtained in about 50 msec.
Then, when a voltage of -2V was applied, the color disappeared in 200 msec. The lifespan was almost the same as in Example 1. Thus, titanium oxide or alumina Al ₂ O ₃
A white background can be easily obtained by mixing white powders such as Also, if colored powders are mixed, it is easy to obtain a background of that color.

Example 3 In Example 1, the counter electrode was made of gold instead of
It was made into a thin film of silver with a thickness of 5000 Å. The characteristics of this ECD were almost the same as those of Example 1. Furthermore, we also fabricated an ECD using a 5000 Å thick carbon film.
The characteristics of this ECD were also almost the same as in Example 1.

Example 4 A product was manufactured using the same manufacturing method as in Example 1, except that the composition of the colored active material composition was changed as follows.

2-tertiarybutylanthraquinone 20 parts Lithium nitride LiN ₃ 15 parts Polyvinylidene fluoride 30 parts Titanium oxide powder 22 parts Dimethyl formamide 100 parts LiN ₃ was pulverized in advance and then mixed.
In this example, an anthraquinone dye that develops color upon reduction was used as the EC material, and an inorganic lithium conductor was used as the ion transfer material.

In the ECD in this example, when -2V is applied to the display electrode, a dark blue display appears,
White contrast reaches 4:1 in 60msec, +
The color disappeared when 2V was applied, and the color completely disappeared in 150 msec. The lifespan was more than ¹⁰⁶ times.

Example 5 The manufacturing method described in Example 1 was the same as in Example 1, except that in the composition of the colored active material composition, the EC material was replaced with allylpyrazoline, which develops color through oxidation, and the colored active material composition was changed as follows. Produced with.

1,5-di(p-methoxyphenyl)-3-
Morpholinophenol-△ ² -pyrazoline (This is a type of allyl pyrazoline.)
50 parts dibenzo-18-crown-6-lithium chloride 30 parts polyvinylidene fluoride 10 parts titanium oxide powder 22 parts dimethylformamide (DMF) 100 parts The ECD in this example turns white in about 40 msec when +2V is applied to the display electrode. The optical contrast was 4:1, and a display with good contrast of deep red against a white background was obtained. Next, when a voltage of 2V of opposite polarity was applied, the color completely disappeared in about 150msec. The lifespan was ¹⁰⁶ times or more.

Example 6 In the manufacturing method described in Example 1, two types of EC materials were used in the composition of the colored active material composition: viologen, which develops color through reduction, and allylpyrazoline, which develops color through oxidation, and the colored active material composition was prepared as follows. It was manufactured using the same manufacturing method as Example 1 except for the following.

1-1'-Dialkyl-4,4'-dipyridium dichloride 23 parts 1,5-di(p-methoxyphenyl)-3-
Morpholinophenol-△ ² -pyrazoline
50 parts dibenzo-18-crown-6-lithium chloride 30 parts polyvinylidene fluoride 10 parts titanium oxide powder 22 parts dimethyl formamide (DMF) 100 parts The ECD in this example turns dark blue when -2V is applied to the display electrode. appears, and 50msec
The white light contrast reached 4:1, and when 0V was applied, the color disappeared in about 300 msec. Next, when +2V was applied to the display electrode, a dark red display appeared, and the white light contrast reached 4:1 in about 40 msec, and when 0V was applied, the color disappeared in about 200 msec.
The lifespan was ¹⁰⁶ times or more.

In this way, by mixing several types of EC materials, we were able to create an ECD that displays multiple colors through voltage control.

Example 7 As shown in FIG. 4, an ITO transparent electrode was provided as a display electrode 2 on a transparent glass substrate by vacuum evaporation. Tetrathiafulvalene (TTF) as EC material
A coating solution was prepared by dissolving 0.1 mole/0.75 mole of polymethacrylonitrile (PMCN) as a synthetic polymer and 0.2 mole/0.2 mole of lithium perchlorate LiClO ₄ as an ion transfer material in propylene carbonate. However, the number of moles of the synthetic polymer is expressed in terms of the number of moles of monomer. This was spinner coated onto the display electrode 2 to a thickness of 2.3 μm.
It was dried in an oven uniformly heated to 80° C. in a N ₂ atmosphere for 8 hours, and further dried in a vacuum oven uniformly heated to 60° C. for 2 hours to obtain a colored active layer 12. 1000Å of gold on top of this
A counter electrode 4 was formed by vacuum evaporation. Furthermore, by covering the periphery of the above laminated structure with a sealing layer 10 of polystyrene resin, a highly reliable ECD could be manufactured.

In the ECD thus manufactured, when a negative voltage was applied to the display electrode 2 with respect to the counter electrode 4, a dark red display appeared, and when a voltage of opposite polarity was applied, the color disappeared. Specifically, by applying a voltage of -3.5V, the white light contrast becomes 3:3 in 100msec.
1, and a high-contrast red display against a gold background was obtained. Then, by applying a voltage of +3.5V of opposite polarity, the color completely disappeared in 100 msec.

Example 8 An ECD with the same structure and composition as in Example 1 was manufactured except for the sealing layer 10, and although the reliability was slightly lower than that in Example 1, it was almost the same as Example 1. Display performance was obtained.

Example 9 As shown in Figure 2, the following coating solution was used on the ITO transparent electrode 2 using a spinner method.
A colored active layer 12 was provided with a thickness of 0.6 μm. The coating solution contains 0.1 mol/1,3-di(P-methoxyphenyl)-5-(P-hydroxyphenyl)-△ ² -pyrazoline as the EC material and polymethacrylonitrile (PMCN) as the synthetic polymer.
The solution contained 0.4 mole/LiClO ₄ as an ion exchange material and 0.1 mole/liClO 4 as an ion exchange material, using a 4:1 mixed solvent of cyclohexanone and propylene carbonate as a solvent. Drying conditions are 2 hours at 60°C in _N2 atmosphere and 2 hours at 60°C in vacuum. On this colored active layer 12, gold is vacuum-deposited to a thickness of 1000 Å, and the counter electrode 4 is
And so. Furthermore, by covering the periphery of the above laminated structure with a sealing layer 10 of polystyrene resin, a highly reliable ECD could be manufactured.

In the ECD thus manufactured, when a positive voltage was applied to the display electrode 2 with respect to the counter electrode 4, a dark yellow display appeared, and when a voltage of opposite polarity was applied, the color disappeared. Specifically, by applying a voltage of -1.5V, the white contrast becomes 3:1 in 100msec.
By applying a voltage of +1.5V with the opposite polarity,
It completely disappeared in 100msec.

In the above examples, polyvinylidene fluoride was used as the synthetic polymer for the colored active material layer, but melamine resin, epoxy resin, silicon resin, acrylic resin, xylene resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer The same results as in the above examples were obtained even when one of the combined resin and polyvinylcarbazole resin, or a mixture of several of them, was used.

As described above, the ECD of the present invention is an all-solid-state ECD having a structure in which a display electrode and a counter electrode are attached on both sides of a colored active material layer in which an EC material and an ion transfer material are dispersed in a synthetic polymer. . This ECD is superior in response speed, environmental resistance, and lifespan compared to conventional all-solid-state ECDs that use solid electrolytes. or,
Compared to ECD using PWA, (1) The response time during coloring is almost the same, but the speed of decoloring is faster. (2) Since various EC materials can be used, various colors can be produced.
Furthermore, as in Example 6, an ECD capable of producing multiple colors can be provided by voltage control. (3) Moisture in ECD does not play a role in coloring or fading, and it is not easily affected by moisture in the air, so it has high environmental resistance. (4) Since a polymer with high moldability is used, it has good adhesion to the electrode and can be manufactured with high productivity. Therefore, it is possible to provide a low-priced ECD. (5) Due to the various factors mentioned above, various effects such as a long life and a practical ECD are obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing a basic example of a conventional solution-type and precipitation-type ECD, and Figure 2 is a conventional fixed-type ECD.
Figure 3 is a cross-sectional view showing a basic example of ECD.
4 is a cross-sectional view of an ECD using PWA. FIG. 4 is a cross-sectional view showing an embodiment of the ECD according to the present invention. In the figure, 1...transparent substrate, 2...display electrode, 3
... Substrate, 4... Counter electrode, 5... Electrolyte, 6... Spacer, 7... Reference electrode, 8... Electrochromic layer, 9... Phosphortungstic acid layer, 10... Seal layer, 11... Ceramic tube, 12... Coloring activity layer.

Claims (1)

[Claims] 1. An all-solid-state electrochromic display having, between a display electrode and a counter electrode, a colored active material layer in which at least one electrochromic material and one or more ion transfer materials are dispersed in a polar polymer. In the device, crown ether, its metal complex lithium nitride, and alkali metal perchlorate were used as ion exchange materials, and polyvinylidene fluoride, polymethacrylonitrile, and derivatives thereof were used as polar polymers. An all-solid-state electrochromic display device featuring: