JPH06313902A - Electrochromic display element - Google Patents

Abstract

(57) [Summary] [Object] The present invention enables multicolor display of an electrochromic display device by using a specific polyaniline. [Structure] The electrochromic display device of the present invention comprises:
On the substrate, the general formula: (In the formula, X ₁ , X ₂ , X ₃ and X ₄ are the same or different and are hydrogen atoms or have a Hammett value δ _m ⁺ of −0.10.
To +0.60, at least one of which is a substituent other than a hydrogen atom. ) Is coated with a polyaniline coating obtained by polymerizing the substituted aniline. This polyaniline is
It can be produced by an electrolytic polymerization method by electrolytic oxidation in a solution containing a substituted aniline and an electrolyte or a chemical polymerization method by an oxidizing agent. In the electrolytic polymerization method, a film can be directly formed on the substrate, and in the chemical polymerization method, the solution can be solubilized by a method such as dedoping, and the solution can be applied on the substrate and dried to form a film. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochromic display element, and more particularly to an electrochromic display element capable of obtaining multiple colors.

[0002]

2. Description of the Related Art A flat display panel represented by a liquid crystal display panel, an electroluminescence (EL) display panel, a plasma display panel, an electrochromic (EC) display panel and the like is a CRT (Cat).
It is drawing attention as a next-generation display panel replacing the hode Ray Tube). In addition, the market demands not only good display quality but also those capable of color display recently for these display panels. Similar requirements have been made for the EC display panel among the above-mentioned panels, and various studies have been conducted to satisfy this requirement. EC
The panel is provided with a special thin film (hereinafter, referred to as “EC substance film”) in which coloration or discoloration occurs due to doping or dedoping of the electrolyte. Then, as the EC substance film, a tungsten trioxide thin film, a Prussian blue thin film, a lanthanoid metal diphthalocyanine,
Vapor-deposited films and the like are known, but recently, a conductive polymer thin film obtained by an electrolytic polymerization method has been used for this EC substance film.

Such a conductive polymer thin film can be manufactured by an electrolytic polymerization method by electrolytic oxidation in a solution containing a monomer and an electrolyte or a chemical polymerization method by an oxidizing agent such as ammonium persulfate. For this manufacturing method,
Japanese Journal of Appli
ed Physics, 23 (3), L189 (198).
4), Polymer, 33 (2), 314 (199).
2). As the monomer, in addition to organic compounds such as pyrrole, thiophene, and furan, and derivatives in which a substituent is introduced into these compounds, unsubstituted aniline is known. In the EC panel, when the conductive polymer film is polythiophene, the color of this film changes from a red state to a blue color when the electrolyte is doped, and when the conductive polymer film is polyaniline. For example, it is known that when an electrolyte is doped, the color of this film changes from a colorless to yellow state to a green to blue color.

[0004]

However, when polythiophene is used as the conductive polymer film, a colored state is obtained in both the doped state and the undoped state, and there is no colorless or white state. There was a problem. Further, when an unsubstituted polyaniline is used as the conductive polymer film, there is a problem that the color at the time of color development is limited to green to blue although there is a colorless state. Therefore, the present invention intends to provide an electrochromic display element capable of multicolor display in order to solve the above-mentioned conventional problems.

[0005]

Means for Solving the Problems As a result of earnest search for a monomer that forms a conductive polymer film in an electrochromic display device, the present inventor has found that the Hammett value δ _m ⁺ of a substituent is
When a polymer of substituted aniline in the range of 1 is used as a color forming layer of an electrochromic display device, it was found that multicolor display is possible, and the present invention has been completed. That is, the present invention provides a general formula on a substrate.

[Chemical 2] (In the formula, X ₁ , X ₂ , X ₃ and X ₄ are the same or different and are hydrogen atoms or have a Hammett value δ _m ⁺ of −0.10.
To +0.60, at least one of which is a substituent other than a hydrogen atom. However, when the above-mentioned substituent contains a hydrocarbon group, the number of carbon atoms is 3
It is the following. In the electrochromic display device, a polyaniline obtained by polymerizing a substituted aniline represented by (4) is applied as a color forming layer.

The present invention will be described in detail below. The electrochromic display device of the present invention comprises a transparent substrate and a light emitting layer made of poly-substituted aniline, which is sequentially deposited on the transparent substrate. The transparent substrate may be any transparent thin plate, and glass is usually used. Further, as the transparent electrode, a transparent conductive foil or thin plate can be used, and examples thereof include materials such as ITO, NESA, and conductive metal foil. Examples of the combination of the substrate and the electrode include transparent conductive glass such as ITO coated glass and NESA glass, and when the substrate is conductive, it is not necessary to form the electrode.

In the electrochromic display device of the present invention, the substituted aniline monomer that enables multicolor display is
At least one substituent is substituted at the ortho position and / or the meta position of aminobenzene, and the Hammett value δ _m ⁺ of the substituent is in the range of −0.10 to +0.60.
When δ _m ⁺ is less than −0.10, the electrochromic display device produced has low color developability. On the other hand, when δ _m ⁺ is greater than +0.60, it is difficult to form a polymer film. is there. Further, if the number of carbon atoms of the hydrocarbon group contained in the substituent is larger than 3, the stability of the poly-substituted aniline coating in the electrolyte is low. Here, some of the substituents of the substituted aniline monomer included in the present invention and their Hammett values δ _m ⁺ are as shown in Table 1 below.

[0008]

[Table 1]

The poly-substituted aniline can be produced by an electrolytic polymerization method by electrolytic oxidation in a solution containing the substituted aniline represented by the above general formula and an electrolyte or a chemical polymerization method by an oxidizing agent such as ammonium persulfate. In the case of the chemical polymerization method, an additive such as an interfacial modifier such as ethylene glycol can be added to the poly-substituted aniline solution. Further, in the case of obtaining a polymerization product thickened in a paste form, it is preferable to use a thickener as an additive, and for example, a known polymer substance such as polymethylmethacrylate can be used.

In order to deposit the polysubstituted aniline as a polymerization product on a substrate or an electrode (hereinafter represented by "substrate"), a polysubstituted aniline film is directly formed on the substrate in the case of the electrolytic polymerization method. can do. In the case of the chemical polymerization method, the poly-substituted aniline can be solubilized by a method such as dedoping and dissolved in a solvent, and then the solution can be applied onto a substrate and dried to form a film. Any solvent can be used as the solvent as long as it has the ability to dissolve the poly-substituted aniline. For example, 1-methyl-2-pyrrolidone, tetrahydrofuran or the like can be used, and these solvents may be used alone or in combination of two or more kinds. In the case of the chemical polymerization method, the application of the poly-substituted aniline solution can be carried out by an appropriate method. For example, when the above solution is liquid, a roll coating method or a dip coating method is preferably adopted. When the solution has a paste form, spin coating or screen printing is preferably used.
Further, the above solution can be directly applied on the substrate by a drawing method such as an ink jet method. Next, the poly-substituted aniline coating film is formed by heating the solution applied or deposited on the substrate. The drying temperature is
Usually 30 to 250 ° C, preferably 80 to 180 ° C
Is. The drying time is 10 minutes to 5 hours, preferably 1 to 3 hours. The film thickness of the formed poly-substituted aniline is appropriately in the range of 0.01 to 5 μm, preferably 0.03 to 1 μm.

According to the present invention, ITO is used as described above.
The poly-substituted aniline film deposited on a substrate such as coated glass or NESA glass can be used as an ECD (electrochromic display) in an electrochromic cell. One form of electrochromic cell utilizing ECD is shown in FIG. That is, in the electrochromic cell shown in FIG. 1, the transparent electrode 4 and the light emitting layer 3 are sequentially deposited on the transparent substrate 1, and the transparent electrode 4 and the transparent electrode 4 are formed through an appropriate gap of about 1 μm to 5 mm. A counter electrode composed of the transparent substrate 5 is arranged, and the gap is filled with the electrolyte 6, for example. As the counter electrode of the ECD, for example, ITO coated glass, NESA glass, transparent conductive metal foil, or the like can be used. Further, as the electrolyte to be filled in the gap between the ECD and the counter electrode,
When the electrolytic solution is an organic solvent such as propylene carbonate, lithium tetrafluoroborate LiBF ₄ , sodium tetrafluoroborate NaBF ₄ , potassium tetrafluoroborate KB
F ₄ , tetrabutylammonium tetrafluoroborate (B
u) ₄ NBF ₄ , lithium perchlorate LiClO ₄ , tetrabutylammonium perchlorate (Bu) ₄ NClO _{4 and the} like. When water is used as the solvent of the electrolytic solution, acidic substances such as hydrochloric acid, sulfuric acid and nitric acid can be used. Furthermore, a polymer semi-solid type in which a salt such as lithium iodide and a polymer substance such as polyvinyl butyral are dissolved in alcohol or the like can be used.

[0012]

In the conventional electrochromic display device using the polymer of the unsubstituted aniline as the coloring layer, the color at the time of coloring is limited to green to blue, whereas the general formula used in the present invention is used.

[Chemical 3] (In the formula, X ₁ , X ₂ , X ₃ and X ₄ are as defined above.) An electrochromic display device having a polyaniline obtained by polymerizing a substituted aniline as a color forming layer is When it is colored, it is colorless, and when it is colored, it can develop a colorful hue of blue to red. When the Hammett value δ _m ⁺ of the substituent in the substituted aniline is small, a color close to blue is produced, and when δ _m ⁺ is large, a color close to red is produced. Thus, the substituent δ _m
By changing ⁺ , it becomes possible to develop various hues.

Further, as described above, when the Hammett value δ _m ⁺ of the above-mentioned substituent is smaller than -0.10, the color developability is lowered, and conversely, when δ _m ⁺ is larger than +0.60, the poly-substitution is carried out. It becomes difficult to form an aniline film. Therefore, in the present invention, the δ _m ^{+ of the} substituent is set in a suitable range of −0.10 to +0.60. Further, when the number of carbon atoms of the hydrocarbon group contained in the substituent is larger than 3, the solubility becomes high, so that the stability of the poly-substituted aniline coating in the electrolyte becomes low and the life of the electrochromic display element is adversely affected. Exert. Therefore, the number of carbon atoms of the hydrocarbon group contained in the substituent is preferably 3 or less.

[0014]

EXAMPLES The present invention will be described more specifically by showing examples below. Preparation of poly o-aminobenzonitrile solution o-aminobenzonitrile 12.
64 g was added and dissolved with stirring to give a solution A. On the other hand, 5.6 g of ammonium persulfate was added to 100 ml of 1N hydrochloric acid and dissolved while stirring to obtain a solution B. After cooling solution A with ice water, solution B was added dropwise over 10 minutes, and the mixed solution was stirred for 15 hours at room temperature. After stirring, the mixture was filtered, and the obtained filtrate was treated with 1N hydrochloric acid 300
It was added to ml and stirred for 5 hours. After stirring, the mixture was filtered and the filtrate was dried under reduced pressure at room temperature for 24 hours to synthesize poly-o-aminobenzonitrile. 3 g of the obtained poly o-aminobenzonitrile was added to 300 ml of 0.1N ammonia water, and the mixture was stirred for 3 hours. After stirring, the mixture was filtered and the filtered substance was dried under reduced pressure at room temperature for 24 hours to obtain solubilized poly o-aminobenzonitrile. 0.2 g of the obtained solubilized poly o-aminobenzonitrile was dissolved in 9.8 g of 1-methyl-2-pyrrolidone, and the solution was filtered through a 0.45 μm filter to obtain a poly o-aminobenzonitrile solution.

Example 1 Using ITO coated glass as a substrate, a poly o-aminobenzonitrile solution was applied onto the substrate by a spin coater and dried in a drier at 150 ° C. for 2 hours to give poly o-aminobenzonitrile on the substrate. A film was formed. The film thickness of the formed poly o-aminobenzonitrile is 0.2 μm.
Met. Next, with respect to the ITO-coated glass having the poly o-aminobenzonitrile coating, the ITO-coated glass was arranged as a counter electrode so that a gap of 20 μm was formed, and lithium perchlorate having a concentration of 1 mol / l was used as the electrolyte. An electrochromic cell was prepared by filling it with a propylene carbonate solution. When a DC voltage of 2.0 V was applied using the poly o-aminobenzonitrile coating of this electrochromic cell as a positive electrode, the ECD changed from colorless to orange to red, and the maximum transmission wavelength λ _Tmax was 780 to 850 nm. When the polarity was reversed and 2.0 V was applied, this color disappeared. Also,
The coloring and erasing operations could be repeated.

Example 2 An electrochromic cell was prepared in the same manner as in Example 1 except that the following polymer semi-solid electrolyte was used as the electrolyte. Lithium iodide 47 mg 2,3-dimercapto-1-propanol 870 mg Tribromoacetic acid 1.04 g Polyvinyl butyral 25 g Butanol 69 ml A direct current voltage of 1.5 V was applied using the poly o-aminobenzonitrile coating of this electrochromic cell as a positive electrode. The ECD changed from colorless to orange, and the maximum transmission wavelength λ _Tmax was 780 nm. 1.5 with the polarity reversed
When V was applied, the orange color disappeared. Further, this coloring and erasing operation could be repeated.

Example 3 ITO coated glass was used as a substrate and 2N sulfuric acid 25.
A solution in which 1.350 g of o-toluidine was dissolved in 2 ml was subjected to electrolytic polymerization at 2.3V. The film thickness of the formed poly o-toluidine was 0.1 μm. Then poly o-
For ITO coated glass with toluidine coating,
As a counter electrode, I
A TO-coated glass is placed and 0.4 mol as an electrolyte
An electrochromic cell was prepared by filling a propylene carbonate solution of lithium tetrafluoroborate having a concentration of / l. When a DC voltage of 2.0 V was applied using the poly o-toluidine coating of this electrochromic cell as a positive electrode, the ECD changed from pale yellow to blue and the maximum transmission wavelength λ _Tmax was 457 to 477 nm. When the polarity was reversed and 2.0 V was applied, the blue color disappeared.
Further, this coloring and erasing operation could be repeated.

Example 4 An electrochromic cell having a polyanthranilic acid film was prepared in the same manner as in Example 3 except that 0.700 g of anthranilic acid was used instead of o-toluidine and the electropolymerization was carried out at 3.0V. It was made. The polyanthranilic acid film of this electrochromic cell is used as a positive electrode for 2.0V.
When a DC voltage of
The color changed to orange, and the maximum transmission wavelength λ _Tmax was 677 nm. When the polarity was reversed and 2.0 V was applied, this color disappeared. Further, this coloring and erasing operation could be repeated.

Example 5 Poly-2,5-poly (2,5-) was prepared in the same manner as in Example 3 except that 2.283 g of 2,5-diethoxyaniline was used in place of o-toluidine and the electric field polymerization was carried out at 2.0V. An electrochromic cell having a diethoxyaniline coating was prepared. When a DC voltage of 2.0 V was applied using the poly2,5-diethoxyaniline coating film of this electrochromic cell as a positive electrode, the ECD changed from colorless to orange and the maximum transmission wavelength λ _Tmax was 600 to 710 nm. When the polarity was reversed and 2.0 V was applied, the orange color disappeared. Further, this coloring and erasing operation could be repeated.

Comparative Example 1 1.173 g of aniline was used in place of o-toluidine,
An electrochromic cell having a polyaniline film was produced in the same manner as in Example 3 except that the electric field polymerization was carried out at 2.0V. When a DC voltage of 2.0 V was applied using the polyaniline coating of this electrochromic cell as a positive electrode, the ECD changed from pale yellow to green to blue, and the maximum transmission wavelength λ _Tmax was 470 to 502 nm. When the polarity was reversed and 2.0 V was applied, this color disappeared, but the hue was only the color of this system.

Comparative Example 2 Polyo-o was prepared in the same manner as in Comparative Example 1 except that 1.000 g of o-chloromethylaniline (δ _m ⁺ of chloromethyl group was -0.14) was used in place of o-toluidine. An electrochromic cell having a chloromethylaniline coating was prepared. When a DC voltage of 2.0 V was applied with the polyo-chloromethylaniline coating film of this electrochromic cell as a positive electrode, the ECD changed from colorless to light blue. When 2.0 V was applied with the polarities reversed, the pale blue color disappeared but the color developability was low.

Comparative Example 3 Using ITO coated glass as a substrate, 2N sulfuric acid 25.
2 ml of o-nitroaniline (nitro group δ _m ⁺ is +
A solution of 0.700 g of 0.674) was subjected to electropolymerization at 3.0 V, but no poly o-nitroaniline coating was formed.

[0023]

Industrial Applicability According to the present invention, a polymer of a substituted aniline having a Hammett value δ _m ⁺ of a substituent within a predetermined range is used for a color-forming layer of an electrochromic display device. A chromic display element can be obtained. Therefore, according to the present invention, not only a multi-color or full-color ECD panel becomes possible, but also various hues can be developed by changing the δ _m ^{+ of the} substituent.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an electrochromic cell using a display device of the present invention.

[Explanation of symbols]

1, 5 ... Transparent substrate, 2, 4 ... Transparent electrode, 3 ... Light emitting layer, 6
…Electrolytes.

Claims (1)

[Claims] 1. A substrate of the general formula: (In the formula, X ₁ , X ₂ , X ₃ and X ₄ are the same or different and are hydrogen atoms or have a Hammett value δ _m ⁺ of −0.10.
To +0.60, at least one of which is a substituent other than a hydrogen atom. However, when the above-mentioned substituent contains a hydrocarbon group, the number of carbon atoms is 3
It is the following. ) A polyaniline obtained by polymerizing a substituted aniline represented by 4) is applied as a color forming layer to form an electrochromic display device.