JP4700490B2 - Display element - Google Patents

Description

  The present invention relates to a display element that utilizes the reduction and reflection of a deposited metal film by utilizing deposition and dissolution of the metal film by electrochemical reduction and oxidation.

With the spread of networks in recent years, the form of electronic books, that is, electronic publishing, has been actively performed in place of books using conventional printing technology. A CRT or a liquid crystal display is generally used as a display for reading information by electronic distribution. However, these have restrictions on the place to read compared with the form printed on the paper which has been used conventionally, and improvement is also required in terms of ease of handling. These displays are not only CRTs but also liquid crystals, and are of a light-emitting type using a backlight, and long-time reading by these may cause high fatigue for ergonomic reasons. Furthermore, there is a problem of power consumption as a substitute for printed matter using paper. For example, reflective liquid crystals have been developed from the standpoint of low power consumption, but the reflectivity is low, the visibility is poor compared to printed matter on paper, and it cannot withstand long-time reading.
JP 2002-258327 A

  In order to solve these problems, the so-called paper-like display or electronic paper including the reflective liquid crystal has been developed by the entry of many manufacturers and research institutions.

  Such techniques include, for example, a method in which colored particles are moved between electrodes by electrophoresis, a method in which dichroic particles are rotated by an electric field, an electrochromic display based on an electrochemical action, and an electrodeposition Various methods such as a display method and an electronic powder fluid method are listed, and all are competing for technological development. However, the above-described technology called paper-like display or electronic paper is based on monochrome display, and the technology related to colorization is still under development. For example, for colorization, it is useful to use a color filter that is used in technologies such as liquid crystal. However, the above-mentioned methods called paper-like display or electronic paper have low reflectivity, so color In some cases, sufficient performance may not be obtained even if a color filter is used.

  The purpose of the present invention is to develop a display element using precipitation and dissolution of a highly reflective metal film, and to realize a high-performance full-color paper-like display using a color filter useful for liquid crystal display technology. It is to provide a possible display element.

(1) A display element according to the present invention includes:
A transparent electrode;
An electrolyte containing a metal salt, at least two of the compounds represented by the following general formula (1), a nonaqueous solvent-based supporting electrolyte and an organic reducing agent;
And an electrode provided opposite to the transparent electrode with the electrolyte interposed therebetween.

・・・（１）
（一般式（１）において、Ｍ^１は、周期律表１５族原子を示し、Ｒ^１、Ｒ^２およびＲ^３は、置換または非置換のアリール基を表し、それぞれは、同一でも異なっていてもよい。）
本発明にかかる表示素子によれば、透明電極と電極との間に設けられ電解質であって、上記特定の化合物を含む電解質を有している。そのため、高反射率の金属膜の析出を実現でき、過剰消去のための電圧を印加した後であっても、高反射率の金属膜を析出させることができる表示素子を提供することができる。

... (1)
(In General Formula (1), M ¹ represents a group 15 atom in the periodic table, R ¹ , R ² and R ³ represent a substituted or unsubstituted aryl group, and each may be the same or different. Good.)
According to the display element of the present invention, the display element includes an electrolyte that is provided between the transparent electrode and the electrode and includes the specific compound. Therefore, it is possible to provide a display element that can realize deposition of a highly reflective metal film and deposit a highly reflective metal film even after a voltage for excessive erasing is applied.

  In addition, the display element concerning this invention can take the following aspect further.

(2) In the display element according to the present invention,
The supporting electrolyte may be at least one compound represented by the following general formula (2) and the following general formula (3).

M ² X ¹ (2)
(In the general formula (2), M ² represents Li, Na, K, Rb, Cs, NH ₄ , and X ¹ represents ClO ₄ , BF ₄ , CF ₃ SO ₂ , PF ₆ ).
(R ⁴ ) _n (R ⁵ ) _m NX ² (3)
(In General Formula (3), R ⁴ represents an alkyl group or an aryl group, and R ⁵ represents an alkyl group. When R ⁴ is an alkyl group, R ⁴ and R ⁵ may be the same. Represents a nitrogen atom, and X ² represents Cl, Br, I, ClO ₄ , BF ₄ , CF ₃ SO ₃ , or PF _6. n = 0, 1 or 2, and m = 4-n.
(3) In the display element according to the present invention,
As the organic reducing agent, hindered amines and hindered phenols can be used.

(4) In the display element according to the present invention,
At least a part of the metal salt may be a complex salt with the compound represented by the general formula (1).

(5) In the display element according to the present invention,
The metal can be silver.

(6) In the display element according to the present invention,
The first transparent electrode _may be at least one selected from _{SnO 2, In 2 O 3,} ZnO group.

(7) In the display element according to the present invention,
The electrode may be a metal film.

(8) In the display element according to the present invention,
The electrode may be made of silver.

(9) In the display element according to the present invention,
The electrolyte may contain an organic solvent.

(10) In the display element according to the present invention,
The organic solvent is dimethylformamide, diethylformamide, N, N-dimethylacetamide, N-methylpropionic acid amide, N-methylpyrrolidone, propylene carbonate, acetonitrile, 2-ethoxyethanol, 2-methoxyethanol, dimethylsulfoxide, It can be at least one of dioxolane, ethyl acetate, tetrahydrofuran, methyltetrahydrofuran, dimethoxyethane, and γ-butyrolactone.

(11) In the display element according to the present invention,
The electrolyte may include a black pigment or a black dye and a mixture thereof.

(12) In the display element according to the present invention,
Furthermore, a transparent substrate provided above the transparent electrode;
And a color filter provided on the transparent substrate.

(13) In the display element according to the present invention,
A light diffusion layer provided on the transparent substrate may be included.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a plan view schematically showing an electrochemical display device according to the present embodiment, and FIG. 2 is a cross-sectional view taken along the line II of FIG.

  As shown in FIG. 1, in the electrochemical display device of the present embodiment, a plurality of display elements 100 are arranged in a matrix. Each display element 100 is provided with a TFT (Thin Film Transistor) 40 which is a driving element, and is driven by an active matrix method. In this embodiment mode, a reflective display device is described as an example.

  As shown in FIG. 2, the display element 100 of the present embodiment is provided with an electrode 10 on a support 8. An electrolyte 20 is provided so as to be in contact with the electrode 10, and a transparent electrode 30 is provided so as to sandwich the electrolyte 20 with the electrode 10. The transparent electrode 30 is electrically connected to the TFT 40 by a wiring layer (not shown). The transparent electrode 30 and the TFT 40 are provided in the color filter layer 50. A transparent substrate 60 is provided on the color filter layer 50.

(Support)
As the support body 8, it plays the role which supports the electrode 10 (refer later reference) formed on it. As a material of the support 8, a glass substrate, a ceramic substrate, a paper substrate, a wood substrate, or the like can be used, but is not limited thereto. Esters such as polyethylene terephthalate, fluorine such as polyamide, polycarbonate, and polyvinylidene fluoride. Polymer substrates such as polymers, polyethers, polyolefins such as polystyrene and polyethylene, and polyimides can be used. In addition to the case where the electrode 10 is provided on the support 8 as described later, the support 8 itself may be formed of a metal film, and this metal film may serve as the electrode 10.

(electrode)
Next, the electrode 10 provided facing the transparent electrode 30 with the electrolyte 20 interposed therebetween will be described. The electrode 10 is not particularly limited as long as it is an electrochemically stable metal. For example, it is preferably formed on the support 8 by silver, platinum, chromium, aluminum, cobalt, palladium or the like. The electrode 10 can be formed by, for example, vapor deposition or sputtering. The electrode 10 may have a predetermined pattern like the transparent electrode 30, but is preferably in the form of a film as shown in FIG. 2, and the use of a silver film is particularly preferable. When the electrode 10 is formed of a silver film, even if the silver film is deposited and dissolved on the transparent electrode 30 a plurality of times, a constant high reflectance can be maintained and repeated with high accuracy. Further, there is an advantage that even if the precipitation dissolution reaction is repeated a plurality of times, there is no adverse effect such as a decrease in reflectance due to devitrification of the deposited silver. Further, the electrode 10 may be formed using the same material as the transparent electrode 30.

(Electrolytes)
Next, the electrolyte 20 will be described. The electrolyte 20 can be composed of an electrolytic solution or a polymer electrolyte layer. Examples of metal ions that are one of the constituent elements of the electrolyte 20, that is, metal ions that can be deposited and dissolved by reduction and oxidation in the display element, include bismuth, copper, silver, lithium, iron, chromium, Nickel ions or combinations thereof may be used. Among these, particularly preferred metal ions are silver ions. When silver ions are used, silver is deposited on the transparent electrode 30, but a metal film made of silver can obtain a high reflectivity and can easily promote a reversible reaction. This is because of the advantages.

  These metal ions are contained in the electrolyte 20 as a metal salt. When the metal ion is silver ion, silver perchlorate, silver nitrate, silver methanesulfonate, silver ethanesulfonate, silver trifluoromethanesulfonate, silver propanolsulfonate, silver acetate, silver sulfate, silver phenolsulfonate , Silver toluenesulfonate, and the like. Particularly preferable examples include silver perchlorate, silver nitrate, silver methanesulfonate, and silver trifluoromethanesulfonate.

  Even when a metal other than silver is used, it is contained in the electrolyte 20 as a metal salt. For example, nickel ions can be added in the form of nickel salts such as nickel sulfate, nickel amidosulfate, and nickel chloride.

  The addition amount of the metal ions contained in the electrolyte 20 is an amount that can form a metal film that can obtain at least a sufficient reflectance. For example, when reducing silver ions to deposit a silver film, the film thickness of the silver film capable of obtaining sufficient reflectance can be 60 nm to 120 nm. When the film thickness of the silver film is 60 nm or less, sufficient reflectivity cannot be obtained. On the other hand, when the film thickness exceeds 120 nm, the silver film is slightly yellow and the reflectivity of the short wavelength portion is lowered. In other words, the reflectance in the visible region varies.

  Furthermore, the electrolyte 20 contains a complex compound capable of forming a complex with a metal. Examples of the complex compound contained in the electrolyte 20 include compounds that can be represented by the following general formula (1).

・・・（１）
（一般式（１）において、Ｍ^１は、周期律表１５族原子を示し、Ｒ^１、Ｒ^２およびＲ^３は、置換または非置換のアリール基を表し、それぞれは、同一でも異なっていてもよい。）

... (1)
(In General Formula (1), M ¹ represents a group 15 atom in the periodic table, R ¹ , R ² and R ³ represent a substituted or unsubstituted aryl group, and each may be the same or different. Good.)

  Examples of the compound represented by the following general formula (1) include the following compounds 1 to 9.

  Further, the electrolyte 20 includes a supporting electrolyte. The supporting electrolyte may be a non-aqueous solvent. Examples of the supporting electrolyte include compounds exemplified by the following general formula (2) and general formula (3).

M ² X ¹ (2)
(In the general formula (2), M ² represents Li, Na, K, Rb, Cs, NH ₄ , and X ¹ represents ClO ₄ , BF ₄ , CF ₃ SO ₂ , PF ₆ ).
(R ⁴ ) _n (R ⁵ ) _m NX ² (3)
(In General Formula (3), R ⁴ represents an alkyl group or an aryl group, and R ⁵ represents an alkyl group. When R ⁴ is an alkyl group, R ⁴ and R ⁵ may be the same. Represents a nitrogen atom, and X ² represents Cl, Br, I, ClO ₄ , BF ₄ , CF ₃ SO ₃ , or PF _6. n = 0, 1 or 2, and m = 4 · n.
Examples of the compound represented by the general formula (2) include NaClO ₄ , LiClO ₄ , KClO ₄ , RbClO ₄ , CsClO ₄ , NH ₄ ClO ₄ , LiBF ₄ , and LiPF ₆ .

Examples of the compound represented by the general formula (3) include (CH ₃ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NClO ₄ , (n-C ₄ H ₉ ) ₄ NClO ₄ , (CH ₃ ) ₄ NBF _4. , (C ₂ H ₅ ) ₄ NBF ₄ , (n-C ₄ H ₉ ) ₄ NBF ₄ , (CH ₃ ) ₄ NCl, (C ₂ H ₅ ) ₄ NCl, (CH ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NBr, (n-C ₄ H ₉ ) ₄ NBr, (n-C ₄ H ₉ ) ₄ NI, C ₆ H ₅ (CH ₃ ) ₃ NClO ₄ , C ₆ H ₅ (C ₂ H ₅ ) ₃ NClO ₄ , C ₈ H ₁₇ (CH ₃ ) ₃ NClO ₄ , (C ₂ H ₅ ) ₄ NPF ₆ , (CH ₃ ) ₄ NCF ₃ SO ₃ , (C ₂ H ₅ ) ₄ NCF ₃ SO ₃ It can be, in _{particular, (CH 3) 4 NClO 4} , (n-C H _{9) 4} NClO ₄ can be suitably used.

  The addition amount of the compounds represented by the general formula (2) and the general formula (3) is not particularly limited as long as the conductivity can be imparted, but is 0.01 mol to 2.0 mol with respect to 1 mol of the metal ion. Addition is preferable, and addition of 0.1 to 1.0 mol is more preferable.

  The electrolyte 20 can contain an organic reducing agent. As the organic reducing agent, hindered amines and hindered phenols can be added. In other words, by using these two kinds of organic reducing agents in combination, after the erasing operation, when ionized metal ions are used to precipitate again as a metal, the reduction reaction is promoted, and the erasing and displaying operations are repeated. There is an advantage that smoothness can be promoted.

  The hindered amines are not particularly limited, but N, N-substituted anilines can be preferably used. Examples of N, N-substituted anilines include N, N-dimethylaniline, N, N-diethylaniline, 4-cyano-N, N-dimethylaniline, 4-acetyl-N, N-dimethylaniline, and 2,6-diisopropyl. -N, N-dimethylaniline, diphenylamine, 4-methoxy-N, N-dimethylaniline, 4-ethoxy-N, N-dimethylaniline, N, N, N ', N'-tetramethyl-1,4-phenylene Examples include diamine, N, N-2,4,6-pentamethylaniline, ethyl N, N-dimethyl-o-aminobenzoate, isopentyl N, N-dimethyl-p-aminobenzoate, and the like. Among these, N, N-dimethylaniline and N, N-diethylaniline can be preferably used.

  The addition amount of the hindered amines is not particularly limited, but is preferably 0.1 mol to 5 mol, more preferably 0.5 mol to 2 mol, relative to 1 mol of the metal ion.

Examples of hindered phenols include the following compounds. 4-tertiary butylphenol, 4-phenylphenol, 2,2'-dihydroxybiphenyl, 4,4'-sec-butylidene diphenol, bisphenol A, 4,4'-cyclohexylidene diphenol, bis (3-allyl- 4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-3 ′, 4′-dimethylphenylsulfone, 4- (4′-isopropoxyphenylsulfonyl) phenol, 4,4′-dihydroxydiphenyl sulfide, 1,4-bis- (4'-hydroxycumyl) benzene, 1,3-bis- (4'-hydroxycumyl) benzene, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 4,4'-dihydroxydiphenyl Sulfone, 2-tert-butyl-6- (3-tert-butyl-2- Droxy-5-methylbenzyl), 2-tert-butyl-6- (3-tert-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate, 2- [1- (2-hydroxy-3) , 5-di-tert-pentylphenyl) ethyl] -4,6-di-tert-pentylphenyl acrylate, 2,2′-methylenebis (6-tert-butyl-4-methylphenol), 4,4′-butylidenebis (6-tert-butyl-4-methylphenol), 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butylbenz [D, f] [1, 3, 2] dioxaphospene and the like;
Examples of the commercially available antioxidants include Sumitizer GP, Sumitizer MDP, Smither WXR, Sumilizer GA00 manufactured by Sumitomo Chemical Co., Ltd., and Irganox 245, Irganox 259, Irganox 1222, Irganox 1035FF, and Irgan manufactured by Ciba Specialty Chemicals.

  Among the compounds exemplified above, 2,2′-methylenebis (6-tert-butyl-4-methylphenol), 6- [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propoxy] -2,4,8,10-tetra-tert-butylbenz [d, f] [1,3,2] dioxaphospene (Sumilyzer GP) can be used particularly preferably.

  The addition amount of the hindered phenols is not particularly limited, but the addition amount is preferably 0.1 mol to 3 mol, more preferably 0.5 mol to 2 mol, relative to 1 mol of the metal ion.

  Furthermore, a complex salt can be used as the metal salt used in the electrolyte 20. As the complex salt, a complex salt of a compound of the above general formula (1) and a metal salt can be preferably used. For example, when silver is used as the metal source, a complex salt represented by the following general formula (4) can be given.

・・・（４）
（上記一般式（４）において、Ｍ^１は周期律表１５属族原子を示し、Ｒ^１，Ｒ^２，Ｒ^３は、置換または非置換のアリール基を示し、それぞれは同一または異なっていてもよい。Ｘは特に限定はないが過塩素酸、硝酸、メタンスルホン酸、トルエンスルホン酸等のカウンター陰イオンである。）

... (4)
(In the above general formula (4), M ¹ represents a group 15 atom in the periodic table, R ¹ , R ² and R ³ represent a substituted or unsubstituted aryl group, and each may be the same or different. X is not particularly limited, but is a counter anion such as perchloric acid, nitric acid, methanesulfonic acid, toluenesulfonic acid, etc.)

  Examples of the compound represented by the general formula (4) include the following compounds 10 to 13.

  The addition amount of the compound represented by the general formula (1) is preferably 0.5 to 10 mol, and particularly preferably 1 to 4 mol, per 1 mol of metal ions. When the amount added is less than 0.5 mole per mole of metal ions, silver can be deposited on the surface of the transparent electrode 30, but a highly reflective silver mirror surface cannot be formed. On the other hand, when the amount exceeds 10 moles, the silver mirror surface deposited on the transparent electrode 30 may become thinner with the lapse of time, and the reflectance may decrease.

The electrolyte 20 is composed of an electrolytic solution or a polymer electrolyte. When the electrolytic layer is composed of an electrolytic solution, a suitable solvent can be selected as appropriate.
As the electrolytic solution of the present invention, preferred solvents are listed below, but are not particularly limited thereto.

Dimethylformamide, diethylformamide, N, N-dimethylacetamide, N-methylpropionic acid amide, N-methylpyrrolidone, propylene carbonate, acetonitrile, 2-ethoxyethanol, 2-methoxyethanol, dimethyl sulfoxide, dioxolane, ethyl acetate, Tetrahydrofuran, methyltetrahydrofuran, dimethoxyethane, γ-butyrolactone;
As the solvent of the electrolytic solution, the above solvents may be used alone, or two or more kinds may be appropriately used in combination. Any of them is preferable as an electrolyte solvent, but in the display element according to the present embodiment, N-methylpyrrolidone is particularly preferable.

  When an electrolytic solution is used as the electrolyte 20, a spacer can be used to obtain a uniform gap between the electrode 10 and the transparent electrode 30. As the spacer, polymer beads, silica beads, glass fibers, etc., or columnar spacers generally used at the time of forming a liquid crystal display can be used. Further, this spacer may be mixed with a sealing material (not shown) between the electrode 10 and the transparent electrode 30.

  When the electrolyte 20 is composed of a polymer electrolyte, it is composed of a matrix polymer. Examples of the matrix polymer include polyalkylene oxides such as polyvinylidene fluoride, polyvinylidene chloride, and polyethylene oxide, or polymers having a repeating unit of polyalkyleneimine and polyalkylene sulfide, polymethyl methacrylate, polyacrylonitrile, and polycarbonate. However, it is not limited to these. The polymer matrix may be used alone or in combination of two or more as appropriate.

  When the electrolyte layer is composed of a polymer matrix, a solvent that can be effectively used as the above-described electrolyte solution is appropriately added and mixed to form a mixture of the polymer matrix and the solvent. Thus, ionic conductivity can be improved by adding a solvent in a polymer matrix. The solvent is appropriately selected depending on the polymer matrix to be mixed. The preferred solvents are listed below, but are not limited thereto.

Water, ethanol, isopropanol, dimethylformamide, diethylformamide, N, N-dimethylacetamide, N-methylpropionic acid amide, N-methylpyrrolidone, propylene carbonate, ethylene carbonate, acetonitrile, 2-ethoxyethanol, 2-methoxyethanol, dimethyl Sulfoxide, dioxolane, ethyl acetate, tetrahydrofuran, methyltetrahydrofuran, dimethoxyethane, γ-butyrolactone, etc .;
Further, an antioxidant can be added to the electrolyte 20. The antioxidant in the electrolyte 20 can prevent oxidation of a metal film such as a silver film deposited on the transparent electrode 30. Therefore, it is possible to suppress the generation of silver oxide or the like generated at the time of dissolving and erasing the silver film, and to remove the colored residue substance derived from silver oxide or the like. Therefore, display characteristics can be improved. Examples of the antioxidant include the above organic reducing agents.

  In addition, by preventing oxidation of the metal film, it becomes possible to repeatedly obtain a highly reflective silver film that is completely different from the pre-erasing precipitation formation when the silver film is formed again, and has high current cycle characteristics. Can be realized.

  The electrolyte 20 can further contain a black pigment or black dye and a mixture thereof. By containing the black pigment or black dye and a mixture thereof, the difference between the reflectance of the deposited metal film and the reflectance at the time of dissolution erasure, that is, the contrast can be emphasized.

  Examples of the black pigment or black dye include pigments such as carbon black and titanium black (black low-order titanium oxide), and oil-soluble dyes such as spirit black, sudan black, oil black and variable black.

(Transparent electrode)
The transparent electrode 30 only needs to be a transparent material. For example, a so-called ITO film or a thin film coated with SnO ₂ or InO ₂ containing In ₂ O ₃ and SnO ₂ or a mixture thereof as a main component is used. preferable. In addition, the above-described ITO film or a thin film coated with SnO ₂ or InO ₂ may be doped with Sn or Sb, or MgO or ZnO may be used.

  The transparent electrode 30 is formed in contact with the color filter layer 50 by vapor deposition or sputtering, for example, or through an overcoat layer (not shown). For the color filter layer 50, refer to the description below.

(Transparent substrate)
As a material of the transparent substrate 60, a transparent glass substrate can be used. Examples of the glass substrate include soda lime glass, low alkali / borosilicate glass, non-alkali / borosilicate glass, non-alkali / aluminosilicate glass, and quartz glass. Without limitation, polymer substrates such as esters such as polyethylene terephthalate, fluoropolymers such as polyamide, polycarbonate, and polyvinylidene fluoride, polyethers, polyolefins such as polystyrene and polyethylene, and polyimides Can be used.

(Other)
In the display element 100 according to the present embodiment, a color filter layer 50 is further provided between the transparent substrate 60 and the transparent electrode 30. Therefore, full color display can be performed by changing the light reflection intensity of the metal film formed on the transparent electrode 30. That is, in the display element 100, the metal deposited on the transparent electrode 30 becomes a reflective film, and external light incident from the transparent substrate 60 passes through the color filter layer 50, is reflected by the reflective film, and passes through the color filter layer 50 again. Then, the light is emitted from the transparent substrate 60 and reaches the observer's eyes, and color display can be realized.

  Furthermore, by using an electrochemical method and utilizing precipitation and dissolution of metal, external reflection can be controlled and gradation display can be achieved.

  The color filter layer 50 is formed of a black matrix 52 and colored portions 54 of red, green, and blue. The black matrix 52 is formed with an acrylic resin or epoxy resin mixed with a black pigment to a film thickness of 0.5 to 2.5 μm, or a metal layer with a low reflectance such as a laminated film of metal chromium and chromium oxide. It is formed to 0.05 to 0.3 μm.

  The red, green, and blue colored portions 54 are formed with a film thickness of 0.5 to 2.0 μm using an acrylic resin, polyvinyl alcohol resin, or epoxy resin in which the three color pigments are individually dispersed. Each pigment color can also be formed as cyan, magenta, or yellow. Further, the color filter layer 50 is a polymer film (gelatin, fish mulled, casein, polyacrylamide, polyvinyl alcohol, etc.) dyed (red, green, blue, cyan, magenta, yellow) with a dye having a predetermined spectral characteristic. ). The colored portion 54 is formed on the transparent electrode 30.

  A planarizing layer may be provided between the color filter and the transparent electrode 30. The planarization layer is preferably formed of a material having high light transmission, and for example, a transparent acrylic resin or epoxy resin can be used. The thickness of the planarizing layer can be 1 μm to 3 μm.

Further, in a color display device using a color filter, a light diffusion layer (not shown) that diffuses and reflects light in order to further reduce the reflection of external light and uneven brightness in the display surface. Can be provided. The light diffusion layer can be provided between the transparent electrode 30 and the transparent substrate 60 or on the surface of the transparent substrate 60 opposite to the surface on which the transparent electrode 30 is provided.
The material used for the light diffusing layer is not particularly limited, but a transparent acrylic resin or epoxy resin is particularly preferable because it needs to be formed of a material having high light transmittance.

  According to the display element 100 according to the present embodiment, the electrolyte 20 including a specific compound is used as the electrolyte 20 provided between the transparent electrode 30 and the electrode 10. Therefore, it is possible to realize deposition of a metal film having a high reflectance. In particular, the electrolyte 20 according to the present embodiment includes the supporting electrolytes represented by the general formulas (2) and (3). This supporting electrolyte mediates the exchange of electrons necessary for the deposition and dissolution of the silver film. Therefore, a fine display element is obtained, and only a minimum amount of metal ions necessary for deposition of a metal film (for example, a silver film) having a desired reflectance may be mixed with the electrolyte 20 in some cases. In this case, the compound that can contribute to the movement of electrons is insufficient, and the precipitation / dissolution reaction may not be sufficiently caused. However, in the display element according to the present embodiment, the above problem can be avoided because the supporting electrolyte is contained. In driving a display device in which a plurality of display elements are arranged in a matrix, a driving method in which a current for dissolving a metal film is applied for each row (or column) may be used. At this time, the display elements connected to one row (or column) are not all in the same state, and there are elements where a metal film is deposited and elements which are erased. If a current for erasing is further applied to the element being erased, an over-erased state may occur, and the reaction rate of subsequent silver film formation may be reduced. However, in the display element according to the present embodiment, even if the organic reducing agent contained in the electrolyte 20 is an element that has been excessively erased, it has an effect of suppressing a decrease in reaction rate. Therefore, a metal film having a good reflectance can be deposited even after the overerasing operation is performed. As a result, a display element with favorable characteristics can be provided.

[Example]
Next, examples of the display element 100 according to the present embodiment will be described. First, the adjustment method of the electrolyte solution (1) thru | or electrolyte solution (6) used as the electrolyte 20 is demonstrated.

  Electrolytic solutions (1) to (6) were prepared by mixing the compounds shown in Table 1.

(Formation of display element)
As the transparent electrode 30, an ITO electrode was formed on a glass substrate which is the transparent substrate 50. As the electrode 10, a silver plate having a film thickness of 300 μm was used. The outer periphery of the glass substrate and the silver plate was bonded with an epoxy adhesive so that the surface of the glass substrate on which the transparent electrode 30 was provided and the silver plate as one electrode 10 face each other. At this time, it adjusted so that the distance between the transparent electrode 30 and the electrode 10 might be set to 200 micrometers. The display element (1) was formed by injecting the electrolytic solution (1) from a part of the adhesive portion with a syringe.

  Similarly, in place of the electrolytic solution (1), electrolytic solutions (2), (3), and (4) were respectively injected to form display elements (2), (3), and (4).

(Evaluation)
A current of 0.03 C / cm ² was passed through the display elements (1), (2), (3), and (4) to deposit a silver film on the ITO electrode surface, and the reflectance was measured from the glass substrate side ( First reflection of silver mirror reflectivity). Thereafter, a current of −0.03 C / cm ² was passed in the direction in which the silver film was dissolved to erase the silver film, and then the reflectance after erasure was measured (first time of reflectance after erasure). Next, a current of −0.03 C / cm ² was flowed 9 times for a total of 10 times. Again, a current of 0.03 C / cm ² was passed to deposit a silver film, and the reflectance of the deposited silver mirror (second time of deposited silver mirror reflectance) was measured. The results are shown in Table 2. The reflectance was measured using a spectrophotometer (Hitachi: U-3310 type).

  As is clear from Table 2, in the display elements (1) to (4), the influence of excessive erasure also in the silver mirror deposition reaction after erasing operation by reverse energization 10 times the energization amount required for silver mirror deposition. It was confirmed that a silver mirror with high reflectivity can be formed.

(Formation of display element)
In Example 2, an ITO electrode is formed by sputtering on a color filter layer in which RGB formed on a glass plate is formed in a stripe shape, and using the electrolytic solution (2) in the description of Example 1, a display element is formed. (5) was formed. A current of 0.03 C / cm ² was passed through the formed display element (5) to deposit a silver film on the surface of the ITO electrode, and the reflectance was measured from the glass substrate side. Next, a current of −0.03 C / cm ² was passed in the direction in which the silver film was dissolved. In addition, 4 times the current of -0.03C / cm ^2, after five circumfluence, again, + 0.03C / cm flowed ^second current to precipitate a silver film. This operation was repeated 10 times, and the reflectance of the formed silver mirror was measured. Further, the formed silver mirror was left for 7 days, and the reflectance was measured. The results are shown in Table 3. The reflectance showed the maximum reflectance of the reflection spectrum measured in each part of RGB. In either case, the formation of a highly reflective silver mirror was obtained, and a color display dependent on each of the RGB color filters was obtained.

As is apparent from Table 3, it was confirmed that even when color display through a color filter was performed, a highly reflective silver mirror showing each color of RGB could be formed without being affected by excessive erasure. Further, it was confirmed that the reflectance was not lowered even after being left for 7 days after the deposition.
[Comparative example]
(Formation of display element)
Next, the display element according to the comparative example is formed. Except for changing the electrolytic solution, it can be performed in the same manner as the method for forming the display element in Example 1. Specifically, a display element (5) in which the electrolytic solution (1) was replaced with the electrolytic solution (5) and a display element (6) in which the electrolytic solution (6) was replaced were formed.

(Evaluation 1)
A current of 0.03 C / cm ² was passed through the display element (5) to deposit a silver film on the ITO electrode surface, and the reflectance was measured from the glass substrate side. The results are shown in Table 4. Next, a current of 0.03 C / cm ² was passed in the opposite direction so that the silver film was dissolved, and the reflectance after the silver film was dissolved was measured. The results are shown in Table 4. Subsequently, the deposition and dissolution of the silver film were repeated a plurality of times, and the reflectance of the deposited silver film and the reflectance after dissolution were measured. Further, finally, the deposited silver film was allowed to stand for 100 hours, and then the reflectance was measured.

  As shown in Table 4, it was confirmed that even after the deposition and dissolution were repeated a plurality of times, the deposited silver film showed a high reflectivity and a high display repeatability and an excellent memory property.

(Evaluation 2)
A current of 0.03 C / cm ² was passed through the display elements (5) and (6), a silver film was deposited on the ITO electrode surface, and the reflectance was measured from the glass substrate side (first time of deposited silver mirror reflectance). . Thereafter, a current of −0.03 C / cm ² was passed in the direction in which the silver film was dissolved, and the reflectivity after erasure was measured (first time of reflectivity after erasure). Next, after a current of −0.03 C / cm ² was flowed twice, a total of 3 times, the reflectance was measured from the glass substrate side. Again, a current of 0.03 C / cm ² was applied to deposit a silver film, and the reflectance of the deposited silver mirror was measured (second time of deposited silver mirror reflectance). The results are shown in Table 5.

  As can be seen from Table 5, in the display element according to the comparative example, it was confirmed that the reflectance of the silver film after excessive erasing was lowered.

  As described above, according to the display element according to the example, it was confirmed that the reflectance almost equal to that of the silver film formed for the first time can be obtained even after the excessive erasing is performed. . As a result, a display element having excellent display characteristics can be provided.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same purposes and results). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

The top view which shows typically the display element concerning this Embodiment. Sectional drawing along the II line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 ... Support body 10 ... Electrode 20 ... Electrolyte 30 ... Transparent electrode 40 ... TFT, 50 ... Color filter layer, 52 ... Black matrix, 54 ... Colored part, 60 ... Transparent substrate, 100 ... Display element

Claims (13)

A transparent electrode;
An electrolyte containing a metal salt, at least two of the compounds represented by the following general formula (1), a nonaqueous solvent-based supporting electrolyte and an organic reducing agent;
A display element including an electrode sandwiching the electrolyte and provided opposite to the transparent electrode.

... (1)
(In General Formula (1), M ¹ represents a group 15 atom in the periodic table, R ¹ , R ² and R ³ represent a substituted or unsubstituted aryl group, and each may be the same or different. Good.) In claim 1,
The display element, wherein the supporting electrolyte is at least one of compounds represented by the following general formula (2) and the following general formula (3).
M ² X ¹ (2)
(In the general formula (2), M ² represents Li, Na, K, Rb, Cs, NH ₄ , and X ¹ represents ClO ₄ , BF ₄ , CF ₃ SO ₂ , PF ₆ ).
(R ⁴ ) _n (R ⁵ ) _m NX ² (3)
(In General Formula (3), R ⁴ represents an alkyl group or an aryl group, and R ⁵ represents an alkyl group. When R ⁴ is an alkyl group, R ⁴ and R ⁵ may be the same. Represents a nitrogen atom, and X ² represents Cl, Br, I, ClO ₄ , BF ₄ , CF ₃ SO ₃ , or PF _6. n = 0, 1 or 2, and m = 4-n. In claim 1 or 2,
A display element using hindered amines and hindered phenols as the organic reducing agent. In any of claims 1 to 3,
At least a part of the metal salt is a complex salt with the compound represented by the general formula (1). In any of claims 1 to 4,
The display element, wherein the metal is silver. In any of claims 1 to 5,
The display element, wherein the first transparent electrode is at least one selected from the group consisting of SnO ₂ , In ₂ O ₃ , and ZnO. In any one of Claims 1 thru | or 6.
The display element, wherein the electrode is a metal film. In any one of Claims 1 thru | or 7,
The display element is made of silver. In any of claims 1 to 8,
The display element, wherein the electric field quality contains an organic solvent. In claim 9,
The organic solvent is dimethylformamide, diethylformamide, N, N-dimethylacetamide, N-methylpropionic acid amide, N-methylpyrrolidone, propylene carbonate, acetonitrile, 2-ethoxyethanol, 2-methoxyethanol, dimethylsulfoxide, A display element, which is at least one of dioxolane, ethyl acetate, tetrahydrofuran, methyltetrahydrofuran, dimethoxyethane, and γ-butyrolactone. In any one of Claims 1 thru | or 10,
The display element, wherein the electrolyte contains a black pigment or black dye and a mixture thereof. In any one of Claims 1 thru | or 11,
Furthermore, a transparent substrate provided above the transparent electrode;
A display element comprising a color filter provided on the transparent substrate. In claim 12,
A display element comprising a light diffusion layer provided on the transparent substrate.

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