JP2002287173A - Electrochromic display element and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochromic display element and an electrochromic display device which display a white color with high reflectance and a black color with high quality. SOLUTION: The electrochromic display element is composed of a first transparent electrode, an electrochromic layer which changes colors by electrochemical oxidation or reduction, a polymer solid electrolyte layer formed by contacting with the electrochromic layer, and a second electrode with the electrochromic layer and the polymer solid electrolyte layer interposed between the second electrode and the first transparent electrode. The electrochromic layer consists of a composite film containing a white pigment and an electrochromic material. Even when the electrochromic material returns into the original color by undoping of anions from the electrochromic layer, the electrochromic layer shields the color and displays the white color because the electrochromic layer contains the white pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochromic display device using a material which changes its color by electrochemical oxidation and reduction as a display material, and further relates to a method for manufacturing the same.

[0002]

2. Description of the Related Art With the spread of computers in offices, the amount of paper used for storing and transmitting documents has been reduced. However, when browsing digital information, the tendency to print and read on paper is still persistent. Therefore, the amount of paper discarded only by temporarily using it tends to increase in recent years. Further, the amount of paper consumed daily for bookcases, magazines, newspapers, and the like is a threat in terms of resources and environment, and these are unlikely to decrease unless the medium changes.

However, in consideration of human information recognition and thinking methods, a "display" such as a CRT (cathoderay tube cathode ray tube) or a transmission type liquid crystal is considered.
We cannot ignore the superiority of "paper" over. Therefore, the realization of electronic paper that combines the "advantage of paper" and the "advantage of a display that can directly handle digital information" is expected.

As a display method of electronic paper, there are a reflective liquid crystal method, an electrophoretic method, a two-color ball display method, an electrochromic method, and the like. The reflective liquid crystal method is a display element that uses a polarizing plate that utilizes the optical rotation and birefringence of the liquid crystal, so it is dark, and the nature of the metal reflective plate causes the white display to be a glare of reflected light. If you hold the screen for a long time, you will put a considerable burden on your eyes. In the electrophoresis method, white pigment or black toner
It is laminated on the electrode by the action of an electric field. The two-color ball display system is composed of a sphere half-colored in two colors, such as white and half black, and uses rotation by the action of an electric field. In either method, a gap is required to allow the fluid to enter, and it is difficult to obtain high contrast because the space cannot be filled in the closest density. In contrast to these display methods, the electrochromic method is advantageous in terms of the burden on the eyes and the contrast.

[0005]

The electrochromic method includes those using inorganic substances typified by tungsten oxide, those using the deposition of organic substances typified by viologen, and those using conductive polymers. There are several types, such as those with controlled gender.

[0006] Among them, the production of inorganic electrochromic materials is mainly performed in a vacuum system, and there is a problem in cost and size. In addition, although black pigments hardly exist in inorganic electrochromic materials, it is obvious that electronic paper needs to be able to display white with high reflectance and black with high quality.

On the other hand, in the method using a conductive polymer, it is known that the higher the conductivity, the stronger the absorption of electrons, and therefore, it looks black, and the electrochromic property can be controlled by an electrochemical method. Have been. Some conductive polymers have conductivity by being doped with a different atom or molecule (dopant). The conductivity of this doping type varies significantly depending on the type of dopant. From an electrochromic point of view, doping can change color dramatically. Further, the method using a conductive polymer has an advantage that it can be easily produced by an electrolytic polymerization method in a solution.

However, this electrochromic material made of a conductive polymer has a strong absorption because it is a conductive material using a π-conjugated system, instead of being capable of producing black color which cannot be produced by inorganic substances. The original color of the polymer itself that appears during undoping is colored deep yellow, red, green, indigo, etc., which is a major problem. In order to use it as electronic paper, it is, of course, necessary to display white with high reflectance.

The present invention has been proposed in view of such technical problems, and an electrochromic display element and an electrochromic display device capable of displaying white having high reflectance and black having high quality have been proposed. It is intended to provide, and further to provide a manufacturing method thereof.

[0010]

In order to achieve the above-mentioned object, an electrochromic display device according to the present invention has a first transparent electrode, an electroactive display element which is in contact with the first transparent electrode, and has an electroactive property. An electrochromic layer that changes color by electrochemical oxidation or reduction; a polymer solid electrolyte layer formed in contact with the electrochromic layer; and the electrochromic layer and the high-electrode layer between the first transparent electrode. A second electrode sandwiching the molecular solid electrolyte layer, wherein the electrochromic layer comprises a composite film containing a white pigment and an electrochromic material.

In the electrochromic display device having the above structure, when the first transparent electrode is turned on and the anion is doped in the electrochromic layer, the electron absorption of the electrochromic material is increased, and a high-quality black is displayed. You.

On the other hand, when the first electrode is turned off and the anion is undoped from the electrochromic layer, the electrochromic material returns to its original color. At this time, the electrochromic layer contains a white pigment. Is hidden, and white is displayed.

On the other hand, the method of manufacturing an electrochromic display element according to the present invention comprises the steps of forming a first transparent electrode on a transparent support, and contacting the first transparent electrode with a white pigment containing a white pigment. A step of forming a molecular material layer, a step of swelling the polymer material layer containing the white pigment with a solvent capable of dissolving the polymer material, and a step of swelling the electrochromic material in a state where the polymer material layer is swollen. A step of forming a composite film containing the electrochromic material and the white pigment by electropolymerization and forming the composite film as an electrochromic layer, a step of forming a polymer solid electrolyte layer on the electrochromic layer, Bonding the support substrate on which the electrodes are formed to the polymer solid electrolyte layer such that the second electrode faces the first transparent electrode. To.

As described above, when the polymer material layer containing the white pigment is swollen and the electrochromic material is electrolytically polymerized in this state, the electrochromic material passes between the molecular chains of the swollen polymer material. As a result, it enters the polymer material layer and is composited with the white pigment. If the above configuration is used as a basic structure and a plurality of these are arranged in a plane, an electrochromic display device that can be driven in a matrix is configured.

The electrochromic display device according to the present invention defines such a structure. A first transparent electrode which is arranged in a matrix corresponding to pixels and is controlled by a driving element, An electrochromic layer that is present in contact with, has an electroactivity and changes color by electrochemical oxidation or reduction, a polymer solid electrolyte layer formed in contact with the electrochromic layer, A second electrode having the electrochromic layer and the polymer solid electrolyte layer sandwiched between transparent electrodes, wherein the electrochromic layer is formed of a composite film containing a white pigment and an electrochromic material. It is characterized by becoming. In the electrochromic display device having such a structure, the electrochromic layer is selectively driven by the driving element, and an image is displayed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electrochromic display device to which the present invention is applied, a method for manufacturing the same, and an electrochromic display device will be described in detail with reference to the drawings.

As shown in FIG. 1, the electrochromic display elements are arranged in order from the viewing surface side (in the figure, from the top).
A transparent electrode 1 serving as a first electrode, an electrochromic layer 2 having electroactivity and changing its color by electrochemical oxidation or reduction, a solid polymer electrolyte layer 3 formed in contact with the electrochromic layer, A basic structure is a laminated structure formed by laminating an electrode 1 and a second electrode 4 formed to face the electrode 1.

Accordingly, the electrochromic layer 2 and the solid polymer electrolyte layer 3 are
And these electrodes are turned on and off.
By turning it off, doping / undoping of the anion into the electrochromic layer 2 is performed, and coloring and decoloring are repeated.

The transparent electrode 1, which is the first electrode, is preferably made of a transparent conductive material because the electrochromic layer 2 can be visually recognized therethrough. As the transparent conductive material, a mixture of In ₂ O ₃ and SnO ₂ , that is, a so-called ITO film or a film coated with SnO ₂ or In ₂ O ₃ is preferably used. These ITO films and S
A film coated with nO ₂ or In ₂ O ₃ may be doped with Sn or Sb, and MgO, ZnO or the like may be used.

The electrochromic layer 2 contains an electrochromic material having electroactivity.
The electrochromic material has a property of discoloring due to electrochemical oxidation or reduction, and changes color to black when the above-mentioned electrode is turned on and a potential difference is applied to the transparent electrode 1 which is one of the opposite electrodes of the capacitor.

As the electrochromic material, any material can be used as long as the material exhibits electrochromic properties. However, a π-conjugated conductive polymer is preferable because it can display high-quality black. is there.

Examples of the π-conjugated conductive polymer include polyacetylene, poly (p-phenylene), polythiophene, poly (3-methylthiophene), polyisothianaphthene,
Examples thereof include poly (p-phenylene sulfide), poly (p-phenylene oxide), polyaniline, poly (p-phenylenevinylene), poly (thiophenvinylene), polyperinaphthalene, and nickel phthalocyanine.

One of the particularly preferable π-conjugated conductive polymers is polypyrrole. this is,
1) Low oxidation potential 2) High Coulomb efficiency 3)
The reason is that the coloration at the time of oxidation is dark and 4) the repetition life is long. The reason why a substance having a low oxidation potential is preferred is that a substance having a low oxidation potential is more stable in a colored state. The reason why a high coulombic efficiency is desirable is that the side reaction is suppressed so much, and that a high coulombic efficiency close to 100% means that the side reaction hardly occurs. Means that the life of the element is prolonged. The fact that the color developed during oxidation is black is an important property for a document display. Polypyrrole is black upon complete oxidation, whereas other polymers are green or reddish black. Therefore, by employing polypyrrole, the black density can be increased, and the contrast can be improved. Another advantage of polypyrrole is its long cycle life. The above-mentioned polypyrrole develops a good black color when doped with anions, but exhibits a deep yellow color when undoped.

A feature of the present invention is that the electrochromic layer 2 contains a white pigment and is composited with the electrochromic material. When the electrochromic layer 2 contains a white pigment, for example, the deep yellow color exhibited when polypyrrole is undoped is concealed, and white with high reflectance can be displayed.

As the above-mentioned white pigment, titanium oxide, aluminum oxide and the like can be used, and further, zinc white and the like can be used. The particle size of the white pigment is desirably smaller than the thickness of the electrochromic layer 2, and the concentration of the white pigment is preferably 25% by weight or less.

The electrochromic layer 2 comprises:
In order to composite the electrochromic material and the white pigment, it is preferable to contain a polymer material.

Examples of the polymer material include polyethylene oxide-based, polyvinyl alcohol-based, polyacrylonitrile-based, methacrylate-based, and vinylidene fluoride-based polymer materials.

Generally, a π-conjugated conductive polymer used as an electrochromic material has poor moldability and workability, is insoluble in a solvent, and is mechanically hard and brittle. These disadvantages can be compensated by forming a composite with the above polymer material. In particular, when a polymer material such as polyethylene oxide, polyvinyl alcohol, and polyacrylonitrile is used, a favorable composite state can be obtained by electrochemical polymerization (so-called electrolytic polymerization). The polymer material expands (swells) during electrolytic polymerization, and as a result, the π
This is because the conjugated conductive polymer diffuses.

Incidentally, in the electrochromic display element, an electrolyte layer for supplying ions to the electrochromic layer 2 is required. At this time, it is desired from the viewpoint of reliability that the display element is an all solid that does not use a liquid, and it is preferable that the electrolyte layer be solidified as much as possible. The use of liquid causes various problems such as leakage of liquid and short circuit between electrodes.

However, when a polymer solid electrolyte (for example, a mixture of polyethylene oxide or the like and a supporting electrolyte, which has ion conductivity) as described below is used, the polymer solid electrolyte layer 3 and the electrochromic layer 2 are used.
Deficiency in adhesion to the film causes a problem. Insufficient adhesion affects smooth ion supply, and naturally leads to a shorter life of the display element and a lower response speed.

Therefore, it is preferable to use the same polymer material as the polymer material contained in the polymer solid electrolyte layer 3 as the polymer material. Taking into account the swelling at the time of complexing with the electrochromic material, specifically, polymer materials such as polyethylene oxide, polyvinyl alcohol, and polyacrylonitrile are preferable, and among these, polymer solid electrolytes are preferable. The material may be selectively used depending on the polymer material used for the layer 3.

As a result, the electrochromic layer 2 and the polymer solid electrolyte layer 3 are networked (integrated) with the same polymer material, and the problem of adhesion is solved. Electrolyte layer 3
Rapid ion conduction is realized between the two.

Even if they are not the same kind of polymer material, a certain effect can be expected as long as the polymer material contained in the polymer solid electrolyte layer 3 has good wettability with the polymer material.

The solid polymer electrolyte layer 3 is provided for supplying ions (anions) to the electrochromic layer 2 as described above, and a supporting electrolyte is dispersed in a matrix polymer material.

The matrix (base material) polymer used for the solid polymer electrolyte constituting the solid polymer electrolyte layer 3 includes:
The skeleton units are-(CCO) n- and-(CC-N) n, respectively.
-,-(CC-S) n-, polyethylene oxide, polyethyleneimine and polyethylene sulfide. These may have a branch as a main chain structure. Further, polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene fluoride, polycarbonate and the like are also preferable.

When forming the polymer solid electrolyte layer 3, it is preferable to add a required plasticizer to the matrix polymer. As a preferable plasticizer, when the matrix polymer is hydrophilic, water, ethyl alcohol, isopropyl alcohol and a mixture thereof are preferable.When the matrix polymer is hydrophobic, propylene carbonate, dimethyl carbonate, ethylene carbonate, γ-butyrolactone are preferable. , Acetonitrile, sulfolane, dimethoxyethane, ethyl alcohol, isopropyl alcohol, dimethylformamide, dimethylsulfoxide, dimethylacetamide, n-methylpyrrolidone and mixtures thereof are preferred.

The solid polymer electrolyte layer 3 is formed by dispersing a supporting electrolyte in the matrix polymer. The electrolyte may be a lithium salt such as LiC
1, LiBr, LiI, LiBF ₄ , LiClO ₄ , L
iPF ₆ , LiCF ₃ SO ₃ and the like, potassium salts such as KCl, KI and KBr, and sodium salts such as NaCl, NaI, NaBr or tetraalkylammonium salts such as tetraethylammonium borofluoride and tetraethyl perchlorate Examples thereof include ammonium, tetrabutylammonium fluoride, tetrabutylammonium perchlorate, and tetrabutylammonium halide. The alkyl chain lengths of the above quaternary ammonium salts may be irregular.

The solid polymer electrolyte layer 3 has an electrochromic layer 2 for improving contrast.
Similarly to the above, a white pigment may be added. Usable white pigments are the same as in the electrochromic layer 2 described above.

The mixing ratio of this white pigment is about 1
-20% by weight, more preferably about 1-10% by weight, even more preferably about 5-10% by weight. Restricting to such a ratio, white pigments such as titanium oxide do not dissolve in the polymer but only disperse.When the mixing ratio increases, the white pigment aggregates, and the optical density is reduced. This is because it becomes uneven. In addition, since the white pigment has no ionic conductivity, an increase in the mixing ratio causes a decrease in the conductivity of the solid polymer electrolyte. Considering both, the upper limit of the mixing ratio is about 20% by weight.

The polymer solid electrolyte layer 3 has a thickness of 20
μm to 200 μm, more preferably 50 μm to 150 μm, even more preferably 70 μm to 150 μm.
μm to 150 μm. The thinner polymer solid electrolyte layer 3 is preferable because the resistance between the electrodes becomes smaller, which leads to a reduction in coloring / decoloring time and a reduction in power consumption. However, when the thickness is 20 μm or less, the mechanical strength is reduced, and pinholes and cracks are generated, which is not preferable.

The second electrode 4 is formed on the surface opposite to the transparent electrode 1 which is the first electrode. The second electrode 4 does not need to be transparent, and may be any metal that is electrochemically stable. Platinum, chromium,
Aluminum, cobalt, palladium, and the like can be formed by forming a film made of these metals.

As shown in FIG. 2, a second electrochromic layer can be formed as the opposing electrochromic layer 5 on the second electrode 4 for the purpose of improving the response speed and the like. In this case, the color of the opposing electrochromic layer 5 is changed to the electrochromic layer 2 on the transparent electrode 1 side.
It is preferable to select a material that does not hinder the color of the image. For example, when the electrochromic material contained in the electrochromic layer 2 on the transparent electrode 1 side is polypyrrole, the opposing electrochromic layer 5 may be made of tungsten oxide. When the electrochromic layer 2 (polypyrrole) on the transparent electrode 1 side is yellow due to undoping of an anion, the tungsten oxide of the opposing electrochromic layer 5 on the opposing side is transparent. Electrochromic layer 2 (polypyrrole) on transparent electrode 1 side
Is black due to the doping of an anion, the tungsten oxide of the opposing electrochromic layer 5 on the opposite side has a blue color.

When the color of the opposing electrochromic layer 5 is different from the color of the electrochromic layer 2 on the transparent electrode 1 side, the white pigment is added to the polymer solid electrolyte layer 3 as described above, so that It is preferable that the color of the electrochromic layer 5 does not substantially disturb. For example, the electrochromic layer 2 on the transparent electrode 1 side
When the same polypyrrole is used for both the opposing electrochromic layer 5 and the electrochromic layer 2 (polypyrrole) on the transparent electrode 1 side is yellow due to undoping of the anion, the opposing electrochromic layer 5 (polypyrrole) is Black color is formed by doping with an anion. In such a case, it is preferable to add a white pigment to the solid polymer electrolyte layer 3 to hide the color development of the opposing electrochromic layer 5.

In the electrochromic display device having the above-described structure, when the first transparent electrode 1 is turned on and the electrochromic layer 2 is doped with an anion, the electrochromic material develops a black color, and a high-quality black is displayed. Is done.

When the first electrode 1 is turned off and the anion is undoped from the electrochromic layer 2, the color returns to the original color of the electrochromic material. At this time, since the electrochromic layer 2 contains a white pigment, This is concealed and white with high reflectance is displayed.

Next, a method for manufacturing the above-described electrochromic display element will be described.

In the manufacture of the above-described electrochromic display element, the key is to combine the electrochromic material, the white pigment, and the polymer material in the electrochromic layer. Therefore, in the following, the description will focus on this composite technology.

To manufacture the above-mentioned electrochromic display element, first, as shown in FIG. 3A, a transparent electrode 12 formed on a transparent substrate 11 is prepared, and as shown in FIG. To form a polymer thin film 13 having a white pigment added thereto.

At this time, the thickness of the polymer thin film 13 may be set according to the desired thickness of the electrochromic layer. For example, if the thickness of the electrochromic layer is 1 μm, the thickness of the polymer thin film 13 is also 1 μm.
To The polymer thin film 13 may be formed by coating by a spin coating method or the like.

In practice, for example, 20% by weight of titanium oxide is added together with 5% by weight of a surfactant to propylene carbonate (containing 0 to 1 mol / liter of electrolyte) in which polyethylene oxide is dissolved at a ratio of 8% by weight. Prepare the prepared solution. At this time, in order to prevent aggregation of the titanium oxide, the mixture is sufficiently stirred using an ultrasonic homogenizer or the like.

This solution is spin-coated on the transparent electrode 12. Spin coating is performed, for example, at 500 rpm for 4 seconds.
Then, it is performed under the conditions of 2500 rpm and 20 seconds.

Then, the substrate is dried on a hot plate at, for example, 80 ° C. for 15 minutes and, as shown in FIG.
A thick white pigment-added polymer thin film 13 is obtained. Next, instead of being laminated on the white pigment-added polymer thin film 13,
An electrochromic material (for example, polypyrrole) is formed by an electrolytic polymerization method so as to be composited with the polymer thin film 13.

Polypyrrole can be easily formed into a thin film by an electrolytic polymerization method. As the electrolytic solution, a solution having a high dielectric constant, such as acetonitrile or propylene carbonate, in which a perchloric acid-based electrolyte such as tetraethylammonium perchlorate or tetraethylphosphonium perchlorate is dissolved at 1 mol / liter is used. . The electrolytic solution is mixed with a pyrrole monomer in an amount of about 0.1 to 1 mol / l. A glass substrate or a plastic substrate with a transparent electrode is used as a working electrode. The counter electrode may be a stainless steel plate or a platinum plate.

The electrolyte containing pyrrole monomer was added with +2
When a current of about 30 mA / cm ^{2 is} applied at a constant current of about mA, pyrrole is polymerized and simultaneously electrolytically oxidized on the transparent electrode serving as a working electrode to form an anion-doped black polypyrrole conductive thin film. This conductive film is 1 to 3 × 10
^It shows an electrical conductivity of about ³ S / cm. Then, when the -1mA constant current is applied about 6mC / cm ² anions are undoped, so exhibits a thick yellow not exhibit a high conductivity.

The above is a very general method for producing a polypyrrole polymer film. The composite with the white pigment-added polymer thin film 13 is formed by applying this manufacturing method.

That is, the transparent substrate 11 provided with the white pigment-added polymer thin film 13 produced by the above-described method is immersed in an electrolytic polymerization solution containing a solvent capable of dissolving the polymer thin film 13, for example, propylene carbonate. As shown in (1), after the polymer thin film 13 is swollen, electrolytic polymerization of an electrochromic material (polypyrrole) is performed.

For example, polypyrrole electrolytic polymerization is performed after immersion in propylene carbonate containing pyrrole at 1 mol / l and electrolyte at 1 mol / l for 15 seconds.
Polyethylene oxide constituting the polymer thin film 13 is:
Although it is soluble in propylene carbonate, not all is immediately dissolved, and within a certain time, the polymer thin film 13 only swells without being peeled off the transparent substrate 11.

Here, the swelling of the white pigment-added polymer thin film 13 is important for compounding. Polymer thin film 1
When the polymer 3 is swollen in advance, pyrrole in the electrolytic polymerization solution passes between molecular chains of polyethylene oxide as a matrix polymer, enters the polymer thin film 13 and is complexed with a polymer material and a white pigment.

In the present invention, the composite film is used as an electrochromic layer. FIG. 3E shows a state in which polypyrrole is compounded, and the transparent electrode 1
In the upper region (the region shown in black in the figure), polypyrrole is complexed.

If the swelling time is too long,
The polymer thin film 13 is dissolved, and the electrochromic material does not diffuse into the polymer thin film 13, but an electrochromic layer made of only the electrochromic material is directly formed on the transparent substrate 11. Therefore, usually, the swelling time is preferably within 1 minute. On the other hand, if the swelling time is too short, the electrochromic layer will be formed on the polymer thin film 13 so as to be laminated, so that care must be taken.

Next, a polymer solid electrolyte layer serving as an electrolyte layer for supplying ions is formed on the composite polymer thin film (electrochromic layer).

At this time, the matrix polymer constituting the solid polymer electrolyte layer is preferably a polymer material of the same kind as the polymer thin film 13.

For example, propylene carbonate in which 8% by weight of polyethylene oxide (of course, any other polymer material may be used as long as it is a polymer material used for a polymer solid electrolyte) is dissolved in the composite electrolyte. It is applied to a thickness of 100 μm on the chromic layer by a blade method. 1
After leaving it for 0 minutes, it is dried for 1 hour in a thermostat at 80 ° C., thereby obtaining a polymer solid electrolyte layer networked at the molecular level with the electrochromic layer.

Thereafter, an electrochromic display element is completed by bonding a second electrode serving as a counter electrode. At this time, the opposing electrochromic layer may be formed also on the second electrode serving as the counter electrode for reasons such as improvement in response speed.

At the time of bonding, a small amount of propylene carbonate is added to the polymer solid electrolyte layer in order to increase the adhesion between the polymer solid electrolyte layer and the second electrode or the opposing electrochromic layer formed thereon. A better bonding state can be realized when the coating is performed after being applied on the layer.

According to the above method, the white pigment, the electrochromic material, and the polymer solid electrolyte layer are composited with the same kind of polymer material or a polymer material having good compatibility to obtain a white color of the electrochromic layer. , Improved response speed, and longer life.

Next, an electrochromic display device driven by a matrix will be described as an application example of the electrochromic display element.

As shown in FIGS. 4 and 5, the matrix driven electrochromic display device has a transparent pixel electrode 22 which is a first transparent electrode controlled by a TFT (Thin Film Transistor) 23 which is a driving element. An electrochromic layer 24 having electroactivity and discoloring by electrochemical oxidation or reduction; and a solid polymer electrolyte layer 25 in contact with the electrochromic layer 24
And a common electrode 26 common to each pixel as a second electrode facing the first transparent electrode.
2 is arranged in a plane (matrix).

The transparent pixel electrode 22 and the TFT 23 are formed so as to constitute one pixel by combining each one, and the pixels are arranged in a matrix on the transparent support 21. As the transparent support 21, a transparent glass substrate such as a quartz glass plate or a white plate glass plate can be used, but not limited thereto, esters such as polyethylene naphthalate and polyethylene terephthalate, polyamide, polycarbonate, and cellulose acetate. Such as cellulose esters, polyvinylidene fluoride, fluoropolymers such as tetrafluoroethylene-hexafluoropropylene copolymers, polyethers such as polyoxymethylene, polyacetals, polystyrene, polyethylene, polypropylene, polyolefins such as methylpentene polymers, and polyimides. Examples include polyimides such as amides and polyetherimides. When such a synthetic resin is used as a support, it can be formed into a rigid substrate shape that does not easily bend, but it can also be formed into a flexible film-like structure.

The transparent pixel electrode 22 is substantially rectangular or square.
It consists of a transparent conductive film formed in a shape pattern.
As shown, each pixel is separated and some of them are
A TFT 23 is provided for each pixel. Transparent pixel
The pole 22 has, for example, In₂O ₃And SnO₂A mixture of
So-called ITO film or SnO₂Or In₂O₃The coat
It is preferable to use a coated film. These ITO films
And SnO₂Or In ₂O₃To the film coated with S
n or Sb may be doped, and MgO or Zn
O or the like can also be used.

The TFT 23 formed for each pixel is selected by a wiring (not shown), and the corresponding transparent pixel electrode 2
2 is controlled. The TFT 23 is extremely effective for preventing crosstalk between pixels. The TFT 23 is formed, for example, so as to occupy one corner of the transparent pixel electrode 22, but may have a structure in which the transparent pixel electrode 22 overlaps the TFT 23 in the laminating direction. Specifically, a gate line and a data line are connected to the TFT 23, a gate electrode of each TFT 23 is connected to each gate line, and one of a source and a drain of each TFT 23 is connected to the data line. The other of the drains is electrically connected to the transparent pixel electrode 22. In addition,
Driving elements other than the TFT 23 are matrix driving circuits used in flat-panel displays, and may be other materials as long as they can be formed on the transparent support 21.

The transparent pixel electrode 22 and the TFT 23
Is in contact with the electrochromic layer 24. As described above, the electrochromic layer 24 is a layer in which an electrically active π-conjugated conductive polymer (electrochromic material), a white pigment, and a polymer material are combined.

The electrochromic layer 24 has a property of changing its color by electrochemical oxidation or reduction, and changes its color to black when a potential difference is applied to the transparent pixel electrode 22 which is one of the opposite electrodes of the capacitor. The solid polymer electrolyte layer 2 is in contact with the electrochromic layer 24 that performs the color formation.
5 are formed.

On the other hand, on the side facing the first transparent electrode,
A common electrode 26 is formed as a second electrode. The common electrode 26 may be made of any metal that is electrochemically stable, but is preferably platinum, chromium, aluminum, cobalt, palladium, or the like. A film made of a good conductor such as a metal film is formed on the support 27. It can be created by forming a film. Further, carbon can be used as a common electrode if the metal used for the main reaction can be sufficiently supplemented beforehand or at any time. As a method of supporting carbon on the electrode for that purpose, there is a method of forming an ink using a resin and printing the ink on a substrate surface. By using carbon, the cost of the electrode can be reduced.

The support 27 does not need to be transparent, and may be a substrate or a film capable of securely holding the common electrode 26 and the solid polymer electrolyte layer 25. For example, a glass substrate such as a quartz glass plate or a white plate glass plate, a ceramic substrate, a paper substrate, or a wood substrate can be used, but not limited thereto. As the synthetic resin substrate, polyethylene naphthalate, polyethylene terephthalate, etc. Ester, polyamide, polycarbonate, cellulose ester such as cellulose acetate, polyvinylidene fluoride, fluorine polymer such as polytetrafluoroethylene-cohexafluoropropylene, polyether such as polyoxymethylene, polyacetal, polystyrene, polyethylene, polypropylene, methylpentene Polyolefins such as polymers, and polyimides
Examples include polyimides such as amides and polyetherimides. When such a synthetic resin is used as a support, it can be formed into a rigid substrate shape that does not easily bend, but it can also be formed into a flexible film-like structure. If the common electrode 26 has sufficient rigidity, the support 27 need not be provided.

As shown in FIG. 5, in order to make the first transparent electrode side and the second electrode face each other, a sealing resin portion 28 holding both supports 21 and 27 is formed around the periphery. With the sealing resin portion 28, both the supports 21, 27, the transparent pixel electrode 22 and the TFT 23, the electrochromic layer 24, the polymer solid electrolyte layer 25, the common electrode 2
6 will be securely held.

In the electrochromic display device having the above-described structure, matrix driving can be performed using the TFT 23. By selectively driving the electrochromic layer 24 in which the white pigment and the electrochromic material are combined, a black quality can be obtained. Image display with excellent white level can be performed.

FIG. 6 shows an example of a circuit diagram of an electrochromic display device. Pixels composed of a TFT 34 and a transparent pixel electrode 35 are arranged in a matrix,
The counter electrode side of the capacitor becomes the common electrode. Data line driving circuits 32 and 32a for selecting each pixel and a gate line driving circuit 33 are provided.
And the gate line 36 are selected by a signal from the signal control unit 31.

[0079]

EXAMPLES Hereinafter, specific examples of the present invention will be described based on experimental results, but it goes without saying that the present invention is not limited to these examples. [Example 1]

(Preparation of Display Electrodes) 10 cm × 1.1 m thick
An ITO film and a TFT (Thin Film Transistor) arranged in a plane at a pitch of 150 μm on a 10 cm glass substrate.
r) was prepared by a known method. A propylene carbonate solution (containing 10% by weight of a surfactant manufactured by Lion Corporation) in which polyethylene oxide is dissolved at a ratio of 8% by weight so that the concentration of titanium oxide (Ishihara Sangyo Co., Ltd., particle size: 200 nm) is 15% by weight. ), And uniformly dispersed by stirring for 60 seconds using an ultrasonic homogenizer.

This polymer solution containing a white pigment was spin-coated on an ITO film. Spin coating is 500 rpm
m, 4 seconds, and then 2500 rpm, 20 seconds. Then, it was dried on a hot plate at 80 ° C. for 15 minutes. Next, a lead portion connected to a drive circuit was formed on the thus-prepared substrate with a titanium oxide-added polyethylene oxide film by a known method.

As shown in FIG. 7, the glass substrate 42 is
It was set in a glass tank 41 for electrolytic polymerization. The electrolytic solution in the glass tank 41 was obtained by dissolving tetraethylammonium tetrafluoroborate at 1 mol / l and pyrrole at 0.1 mol / l in propylene carbonate. In the glass bath 41 for electrolytic polymerization, in addition to the glass substrate 42, a platinum substrate 43 as a counter electrode and a silver wire 44 as a reference electrode were arranged as shown in FIG.

15 seconds after immersing the substrate 42 with the titanium oxide-added polyethylene oxide film in the electrolytic solution,
A current of 2 mA is supplied from the drive circuit as a whole.
(30 mC / cm ² ). On the ITO, a composite film of polypyrrole and titanium oxide-added polyethylene oxide, which was black and was doped with a tetrafluoroborate anion, was formed.

Next, the glass substrate was placed in a glass bath containing an electrolytic solution obtained by dissolving tetraethylammonium tetrafluoroborate in propylene carbonate at 1 mol / liter, and a current of -1 mA was applied to the glass container. Electric current was supplied until the current reached 0.8C (8 mC / cm ² ), and ions doped in polypyrrole during electrolytic polymerization were dedoped. The composite film of polypyrrole / polyethylene oxide added with titanium oxide turned creamy. Next, the substrate was taken out, washed with ethanol, and dried in vacuum.

(Preparation and Coating of Solid Polymer Electrolyte) 8 parts by weight of polyvinylidene fluoride having a molecular weight of about 350,000 and 1 mol of tetraethylammonium tetrafluoroborate were dissolved in propylene carbonate.
Twenty-five parts by weight of 00 nm titanium oxide was added, and this was uniformly dispersed with an ultrasonic homogenizer. This polymer solution is applied to the substrate at 1000 rpm for 4 seconds, and then for 30 seconds.
Spin coating was performed at 00 rpm for 30 seconds, followed by drying on a hot plate at 80 ° C. for 15 minutes.

(Lamination of Second Electrode Substrate) On the glass substrate on which the above-mentioned composite film was formed and on which a polymer solid electrolyte layer was formed, 10 μl of propylene carbonate was dropped, and the second electrode substrate was laminated. Immediately bonded. Then, the end face of the bonding was sealed with an epoxy-based ultraviolet curable resin (Photorec, manufactured by Catalyst Chemicals, Inc.) as a sealant.

The color (whiteness at the time of undoping anions) of the thus obtained electrochromic display device
Was an L * a * b * color system, the b * value was +11, and the change response time from cream to black was 50 s.
The repeating durability (response time count until 10% longer) also exceeds the 10 ^6.

Comparative Example 1 An electrochromic display element was manufactured in the same manner as in Example 1 except that the electrochromic layer was a film made of polypyrrole alone.

The thus obtained electrochromic
The color of the color display element is L * a * b * color system, and b * value is
+50, and the change response time from cream to black is
It was 65 s. Repeat durability (response time is 10% longer
Number of times until it becomes 10) ²It was about.

Example 2 In this example, a counter electrochromic layer was formed on a second electrode substrate. Others are the same as the first embodiment.

(Preparation of Opposing Electrochromic Layer) The second electrode substrate was placed in a glass tank for electrolytic polymerization. The electrolytic solution in the glass tank was obtained by dissolving tetraethylammonium tetrafluoroborate at 1 mol / l and pyrrole at 1 mol / l in propylene carbonate. In the glass bath for electrolytic polymerization, in addition to the second electrode substrate,
A platinum substrate was provided as a counter electrode, and a silver wire was provided as a reference electrode. After the second electrode substrate was immersed in the electrolytic solution, a current of ² mA was applied from the drive circuit to the whole until the amount of electricity passed became 3 C (30 mC / cm ² ). ITO
On the film, a polypyrrole film having a black color was formed by doping with a tetrafluoroborate anion.

Next, the second electrode substrate is
-Tetraethylammonium tetrafluoride in carbonate
Electrolyte obtained by dissolving 1 mol / l of roborate
And placed in a glass tank containing
0.8C (8mC / cm ²) Until it becomes
The ions doped in polypyrrole during depolymerization
Dedoped. The polypyrrole film turns creamy
Was. Electrochromic display obtained in this way
The element colors are L * a * b * color system, and b * value is +11.
The response time from cream to black is 120m
s.

Further, the durability against repetition (response time is 10%
The number of times until it became longer exceeded 10 ⁶ . further,
To measure the repetition durability, a 1 Hz square wave was
The application of 1.2 V was continued, and the change in the response waveform was observed. 12
After a day, the response time had not changed much at 125 ms.

Comparative Example 2 An electrochromic display element was manufactured in the same manner as in Example 2 except that the electrochromic layer and the opposing electrochromic layer were made of a single film of polypyrrole.

The color of the electrochromic display device thus obtained was L * a * b * color system, the b * value was +50, and the change response time from cream to black was 350 ms. . Repeat durability (response time is 10
% Number until long) it was about 10 ^3. In addition, in order to measure the repetition durability, a 1 Hz rectangular wave was continuously applied at ± 1.2 V, and a change in a response waveform was observed.
I was late.

Comparative Example 3 An electrochromic display element was produced in the same manner as in Comparative Example 2 except that titanium oxide was not added to the polymer solid electrolyte layer. The electrochromic display element was also blackened when anion was undoped.

[0097]

As is clear from the above description, in the electrochromic display element and the electrochromic display device of the present invention, since the electrochromic material and the white pigment are combined, the white and the high-reflectivity can be obtained. Good black can be displayed.

Further, according to the method of manufacturing an electrochromic display device of the present invention, an electrochromic material, a white pigment, and a polymer material can be in a good composite state. Can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one configuration example of an electrochromic display element.

FIG. 2 is a schematic sectional view showing another configuration example of the electrochromic display element.

FIG. 3 is a schematic diagram for explaining a process of compounding an electrochromic material and a white pigment-added polymer thin film.

FIG. 4 is a schematic perspective view showing a configuration example of an electrochromic display device driven by a matrix.

5 is a schematic sectional view of a main part of the electrochromic display device shown in FIG.

FIG. 6 is a circuit diagram of an electrochromic display device.

FIG. 7 is a schematic perspective view showing a configuration of an electrolytic cell used for electrolytic polymerization in Examples.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transparent electrode 2 electrochromic layer 3 polymer solid electrolyte layer 4 second electrode 5 opposing electrochromic layer 21 transparent support 22 transparent pixel electrode 23 TFT 24 electrochromic layer 25 polymer electrolyte layer 26 common electrode 27 support 28 sealing Resin part

Claims (16)

[Claims] A first transparent electrode controlled by a driving element, an electrochromic layer present in contact with the transparent electrode, the electrochromic layer having electroactivity and discoloring by electrochemical oxidation or reduction; A polymer solid electrolyte layer formed in contact with the electrochromic layer; and a second electrode having the electrochromic layer and the polymer solid electrolyte layer interposed between the first transparent electrode. Wherein the electrochromic layer comprises a composite film containing a white pigment and an electrochromic material. 2. The electrochromic display device according to claim 1, wherein the electrochromic material is a π-conjugated conductive polymer. 3. The electrochromic display device according to claim 2, wherein said electrochromic material is polypyrrole. 4. The electrochromic display device according to claim 1, wherein said white pigment is titanium oxide. 5. The electrochromic display device according to claim 1, wherein the electrochromic layer contains a polymer material. 6. The electrochromic display device according to claim 5, wherein the polymer material is a polymer material of the same kind as the polymer material contained in the polymer solid electrolyte layer. 7. The electrochromic display device according to claim 5, wherein the polymer material is a polymer material having good wettability with the polymer material contained in the polymer solid electrolyte layer. 8. The electrochromic display device according to claim 5, wherein said polymer material is polyethylene oxide. 9. The electrochromic display device according to claim 1, wherein the solid polymer electrolyte layer contains a white pigment. 10. The electrochromic display device according to claim 1, further comprising a second electrochromic layer between the polymer solid electrolyte layer and the second electrode. 11. A step of forming a first transparent electrode on a transparent support, a step of contacting the first transparent electrode to form a polymer material layer containing a white pigment, Swelling the polymer material layer containing the polymer material with a solvent capable of dissolving the polymer material, and electrolytically polymerizing the electrochromic material in a state where the polymer material layer is swollen, so that the electrochromic material and the white A step of forming a composite film containing a pigment and forming the composite film as an electrochromic layer, a step of forming a polymer solid electrolyte layer on the electrochromic layer, and a step of forming a support substrate on which the second electrode is formed by a second electrode A step of adhering on the polymer solid electrolyte layer so as to face the first transparent electrode. 12. The method according to claim 12, wherein the electrochromic material is π
12. A conjugated conductive polymer.
A method for producing the electrochromic display element according to the above. 13. The polymer solid electrolyte layer, wherein the same polymer material as that of the polymer material layer is used, and the polymer solid electrolyte layer is formed by coating on the electrochromic layer. 12. The method for producing an electrochromic display element according to item 11. 14. A second electrochromic layer is formed on the second electrode in advance, and a supporting substrate is bonded so that the second electrochromic layer contacts the solid polymer electrolyte layer. Claim 1 characterized by the following:
2. The method for producing an electrochromic display element according to item 1. 15. A first transparent electrode arranged in a matrix corresponding to pixels and controlled by a driving element, and a first transparent electrode which is in contact with the transparent electrode and has an electroactive and electrochemical property. An electrochromic layer that changes color by oxidation or reduction; a solid polymer electrolyte layer formed in contact with the electrochromic layer; and the electrochromic layer and the solid polymer electrolyte layer between the first transparent electrode An electrochromic display device, comprising: a second electrode sandwiching the second electrode, and the electrochromic layer is made of a composite film containing a white pigment and an electrochromic material. 16. The electrochromic display device according to claim 15, wherein said second electrode is a common electrode.