JPH0578805B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a novel electrochromic (hereinafter, "electrochromic" is abbreviated as EC) display device. [Prior Art] An EC display device (hereinafter abbreviated as ECD) that develops color by applying a voltage similar to that of a dry cell battery and fades to its original colorless transparency by applying a reverse voltage.
Active research is being carried out to put this technology to practical use in numeric and other display means using day-shaped seven segments, reflective mirrors, windows that can change the amount of transmitted light, and devices that control the amount of transmitted light. As one of them
Using reduction chromogenic EC substances such as WO ₃ and MoO ₃
There is an ECD (see Special Publication No. 52-46098). For these EC substances to develop color, electrons (e ^- ) are required
Simultaneous injection of cation and cation (X ⁺ ) is required, and the reaction formula for color development and decolorization is believed to be as follows. When decoloring: WO ₃ +ne ^- +nX ⁺ ↓↑ ↓↑ When developing color: XnWO ₃ And as the cation (X ⁺ ), H ⁺ , which has a small ionic radius and is easily mobile, is mainly used. These cations do not need to be cations all the time, but only need to be generated when a voltage is applied and an electric field is formed, so water is used as a cation source, especially in the case of H ⁺ . Water decomposes in an electric field as H ₂ O→H ⁺ +OH ^- . Very small amounts of water appear to be sufficient, and the amount of water that is naturally drawn into the WO ₃ layer from the atmosphere is often sufficient. Therefore, when the cation is H ⁺ , (1) During color development, (cathode side) WO ₃ +ne ^- +nH ⁺ →HnWO ₃ nH ₂ O→nH ⁺ +nOH ^- (anode side) n(OH ^- ) → n /2H ₂ O+ (n/4)
The reaction O ₂ ↑ + ne ^- is estimated, and (2) during decolorization, the reaction (anode side) HnWO ₃ →WO ₃ +ne ^- +nH ⁺ (cathode side) ne ^- +nH ⁺ →n/2H ₂ ↑ occurs. It is estimated to be. As is clear from these equations, in reality, water is consumed by the drive of Tokuko No. 52-46098, so unless water is quickly supplied from the atmosphere, the color will not develop, and O ₂ The disadvantage was that delamination occurred due to the release of gas and H ₂ gas. Therefore, an all-solid-state ECD was proposed in which ``two layers of an electronic insulating layer, which is a good ion conductor, and iridium hydroxide'' were provided next to _{the three} WO layers (Japanese Patent Application Laid-Open No. 1983-1999).
(See No. 4679). This ECD has a five-layer structure, as shown in FIG. In this ECD, an iridium hydroxide layer is used as an electrolytic redox layer, and during color development of WO ₃ , the iridium hydroxide layer is used on the anode side.

[Problem to be solved by the invention]

However, when conventional ECDs (Fig. 3) are subjected to long-term high-temperature durability tests, the color remains even when the color is erased, and the color does not become the original colorless and transparent, resulting in a decrease in the contrast between color development and fading. There was found. Therefore, it is an object of the present invention to overcome the drawbacks of conventional ECDs,
In other words, the purpose is to improve the decrease in contrast when subjected to long-term high-temperature durability tests. [Means for Solving the Problems] As a result of intensive research, the present inventors discovered that two layers of an iridium hydroxide or oxide layer and a second electrode layer adjacent thereto.
Instead of a layer, "a transparent dispersion layer formed of a dispersoid made of iridium metal itself or its oxide or hydroxide and a transparent solid dispersion medium made of a conductive inorganic oxide or inorganic fluoride," A transparent dispersion layer in which the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles, the layer being formed by a vacuum thin film formation technique or a thick film method.
It was discovered that the object can be achieved by using it as an electrode layer, and the present invention was completed. Therefore, the present invention provides, firstly, a first electrode layer, a reduction color-forming electrochromic layer adjacent to the electrode layer, and a first electrode layer adjacent to the electrochromic layer either directly or via a transparent ion conductive layer. An electrochromic display device comprising a laminated second electrode layer in which at least one of the first and second electrode layers is transparent, wherein the second electrode layer is made of iridium metal itself or an oxide thereof. Alternatively, it is a transparent dispersion layer formed of a dispersoid made of a hydroxide and a transparent solid dispersion medium made of a conductive inorganic oxide, and the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles. and the transparent dispersion layer is formed by a vacuum thin film formation technique or a thick film method.'' Second, the present invention provides a first electrode layer that is transparent or reflective; an electrochromic display comprising a layer, a reduction color forming electrochromic layer formed on the first electrode layer, and a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer. In the device, the second electrode layer is a transparent dispersion layer formed of a dispersoid made of iridium metal itself or its oxide or hydroxide and a transparent solid dispersion medium made of a conductive inorganic oxide, An electrochromic display characterized in that the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and the transparent dispersion layer is formed by a vacuum thin film forming technique or a thick film method. equipment”. Furthermore, the present invention provides, thirdly, "a first electrode layer, a second electrode layer existing on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer; A reduction color-forming electrochromic layer formed on the electrode layer, a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer, and a third electrode formed on the ion conductive layer. In an electrochromic display device formed by stacking layers and in which at least one of the first or third electrode layer is transparent, the second electrode layer is made of iridium metal itself or its oxide or hydroxide. A transparent dispersion layer is formed of a dispersoid consisting of a conductive inorganic oxide and a transparent solid dispersion medium consisting of a conductive inorganic oxide, the dispersoid being dispersed in the transparent solid dispersion medium in an ultrafine state, and An electrochromic display device characterized in that the transparent dispersion layer is formed by a vacuum thin film formation technique or a thick film method. The present invention also provides, fourthly, a first electrode layer, a reduction color-forming electrochromic layer adjacent to the electrode layer, and an electrochromic layer adjacent to the electrochromic layer directly or via a transparent ion conductive layer. In an electrochromic display device in which a second electrode layer is laminated and at least one of the first and second electrode layers is transparent, the second electrode layer is made of iridium metal itself or its oxide or A transparent dispersion layer formed of a dispersoid made of a hydroxide and a transparent solid dispersion medium made of an inorganic fluoride, the dispersoid being dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and The present invention provides an "electrochromic display device" characterized in that the transparent dispersion layer is formed by a vacuum thin film forming technique or a thick film method. The present invention also provides, fifthly, a "transparent or reflective first electrode layer; a second electrode that is present on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer; an electrochromic display comprising a layer, a reduction color forming electrochromic layer formed on the first electrode layer, and a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer. In the device, the second electrode layer is a transparent dispersion layer formed of a dispersoid made of iridium metal itself or its oxide or hydroxide, and a transparent solid dispersion medium made of an inorganic fluoride, and the dispersoid are dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and the transparent dispersion layer is formed by a vacuum thin film formation technique or a thick film method. I will provide a. In addition, sixthly, the present invention provides: a first electrode layer, a second electrode layer existing on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer; a reduction color forming electrochromic layer formed on the layer, a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer, and a third electrode layer formed on the ion conductive layer. In an electrochromic display device in which at least one of the first or third electrode layer is transparent, the second electrode layer is made of iridium metal itself or its oxide or hydroxide. and a transparent solid dispersion medium made of an inorganic fluoride, the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and the transparent dispersion layer The present invention provides an electrochromic display device characterized in that the device is formed by a vacuum thin film formation technique or a thick film method. [Function] The first electrode layer A or the third electrode layer E used on the display side must be transparent, and transparent electrode materials include, for example, SnO ₂ , In ₂ O ₃ , ITO
(In ₂ O ₃ mixed with about 5% SnO ₂ ) etc. are used. The thickness of the electrode layer A or E is generally 0.01 to 0.5 μm, although it depends on the transparency and resistance. Therefore, the electrode layer A or E is generally made by a vacuum thin film forming technique such as vacuum evaporation, reactive evaporation, ion plating, reactive ion plating, or sputtering, but in some cases, an organometallic compound may be used. For example, it may be produced by a so-called thick film method in which a solution of a metal alcoholate or its oligomer is applied and baked to form a film. As already known, amorphous WO ₃ or MoO ₃ is used for the reduction color forming EC layer B. these
The EC layer is generally 0.01~
It is formed to a thickness of several μm. The transparent ion conductive layer C is provided as necessary in order to give the ECD of the present invention a memory property, that is, the property that the coloring state is maintained even after the voltage application is stopped after coloring. Examples of materials include: Tantalum oxide (Ta ₂ O ₅ ) containing a small amount of water,
Niobium oxide (Nb ₂ O ₅ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), hafnium oxide (HfO ₂ ), yttrium oxide (Y ₂ O ₃ ), lanthanum oxide (La ₂ O ₃ ), silicon oxide ( SiO ₂ ) Magnesium fluoride, zirconium phosphate, or a mixture thereof; Sodium chloride, potassium chloride, sodium bromide, potassium bromide, Na ₃ Zr ₂ Si ₂ PO ₁₂ , Na _{1+X
Solid electrolyte such as ZrSi _ _ _} Copolymers with sulfonic acid, hydrated vinyl polymers such as hydrated methyl methacrylate copolymers, hydrated polyesters, etc.; Electrolytes such as sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid,
acids such as butyric acid, oxalic acid or their aqueous solutions;
Aqueous solutions of alkalis such as sodium hydroxide, potassium hydroxide, aqueous solutions of solid strong electrolytes such as sodium chloride, lithium chloride, potassium chloride, lithium sulfate; semi-solid gel electrolytes, such as electrolyte aqueous solutions with gelling agents such as polyvinyl alcohol, CMC,
Examples include gelatinized with agar, gelatin, etc. The transparent ion conductive layer C blocks the movement of electrons, but allows the movement of ions, and is, after all, a good conductor rather than an insulator. The transparent ion conductive layer C is formed by vacuum thin film forming technology, thick film method, encapsulation, injection, coating, or other means. The thickness of the C layer is 0.001μm to 1mm depending on the material.
The rank varies. The second electrode layer D1 of the present invention consists of a transparent dispersion layer D1, which consists of a dispersoid D11 consisting of iridium metal itself or its oxide or hydroxide.
and a transparent solid dispersion medium D12. Dispersoid D1
Among these, oxides or hydroxides are preferable as 1. As the dispersion medium D12, SnO ₂ , In ₂ O ₃ ,
Transparent conductive inorganic oxides such as ITO and ZnO,
Transparent inorganic fluorides such as MgF ₂ and CaF ₂ are used. Among these, SnO ₂ , In ₂ O ₃ , ITO, ZnO
is preferred. The method for manufacturing such a transparent dispersion layer D1 is limited to a vacuum thin film formation technique or a thick film method. A specific example of the method is as follows. In the following explanation,
M ₁ is a metal element constituting the dispersoid D11, M ₁ O
stands for its oxide, M ₂ stands for the metal element constituting the dispersion medium D12, M ₂ O stands for its oxide, M ₂ F
means fluoride. () Vacuum deposition by resistance heating, electron beam heating, radio frequency heating or laser beam heating: (-a) Non-reactive case M ₁ , M ₁ O M ₂ O, M ₂ F are used as evaporation source materials. Note that Ir, which is M ₁ , is in an active state immediately after vapor deposition, so it may change to M ₁ O simply by being exposed to the atmosphere. (-b) In the case of reactivity, M ₁ , M ₁ O M ₂ , M ₂ O, M ₂ F are used as evaporation source materials in the presence of O ₂ gas and with activation means (e.g. high frequency application or heating). . () High frequency sputtering: (-a) Non-reactive case M ₁ , M ₁ O M ₂ O is used as a multi-element or composite target in the presence of an inert gas. (-b) In the case of reactivity, M ₁ , M ₁ O M ₂ , M ₂ O are used as multiple or composite targets in the presence of O ₂ gas (an inert gas may be added). () Direct current sputtering: M ₁ M ₂ is used as a multi-element or composite target in the presence of O ₂ gas (inert gas may be added). () Others In any of the above methods (), (), (),
After forming a mixed metal thin film of _M1 and _M2 , it is oxidized by heating to, for example, 250 to 300°C.
The dispersion layer D1 is changed to a dispersion layer D1 of M ₁ and M ₂ O or a dispersion layer D1 of M ₁ O and M ₂ O. Examples of M ₂ that can be used in this method include Sn, In, and the like. In addition, although it was mentioned earlier that M ₁ O means an oxide, when water exists near M ₁ O, M _{1 O}
As understood from the fact that O.H ₂ O can also be written as M ₁ (OH), it can also be interpreted as a hydroxide rather than an oxide. Therefore, the metal oxide and hydroxide constituting the dispersoid D11 are not strictly distinguished. In any case, it is necessary that the dispersoid D11 be dispersed in the transparent dispersion medium D12 in the form of extremely fine particles, and for this reason, it is necessary to use the above-mentioned vacuum thin film forming technique to manufacture the dispersion layer D1. Otherwise, the dispersed layer D1 is formed by a thick film method. In this method, a mixture of an organic metal compound such as a metal alcoholate or an oligomer thereof is applied and fired to form a film. Thereby, a transparent dispersion layer D1 is formed. The thickness of the transparent dispersion layer D1 is generally 0.005μ.
m to 1 mm is sufficient. As mentioned above, cations are necessary for coloring of the reduction color-forming EC layer B, and the layers B, C, and D1
It is necessary to include cations or a cation source that releases cations upon application of a voltage in at least one layer of the layer B and D1, but in practice, when the cations are included in layer B and layer D1, the cations are protons (H ⁺ ).
In practice, the cation source is water (H ₂ O).
limited to. In the case of water, it often enters the layer naturally from the atmosphere even if it is not specifically included during the production of ECD. If a reflective ECD is desired, in the present invention,
Either the first electrode layer A or the third electrode layer E can be made of a reflective conductive material, such as Al, Ag, or Au. Otherwise, a transparent electrode material can be used and a reflective layer added behind it. Since the ECD is formed in the form of a thin plate, it is often formed on a substrate, but the substrate may be placed on any side of the electrode. In this way, the ECD of the present invention is constructed. The ECD of the present invention generally includes an electrode layer A, a reduction coloring EC layer B, optionally an ion conductive layer C, and a second electrode layer D.
It has a three-layer or four-layer structure formed by sequentially laminating layers 1 and 2, but it may also have a structure as shown in FIGS. 2A and 2B. In the figure, E is the third electrode layer (auxiliary electrode)
It is. When a DC voltage of about 1.0 to 1.8 volts is applied to this ECD, it develops a blue color in 0.01 to several seconds, and if the C layer is present, this coloring state is maintained for a relatively long time even if the voltage application is stopped, and the same level When a reverse voltage of 2 is applied, it returns to its original colorless and transparent state in a slightly shorter time than the time required for color development. It will take some time, but the first and second
The color disappears even if the electrodes are short-circuited. Hereinafter, the present invention will be specifically explained with reference to Examples. (Example 1) A glass substrate S is prepared, and the following conditions are applied on it: Evaporation source: Binary system of metal Sn and metal Ir Degree of vacuum: 5×10 ^-6 Torr O ₂ Partial pressure: 3×10 ^-4 Torr A second electrode layer D1 consisting of a transparent dispersion layer D1 having a thickness of 700 Å was formed by high-frequency ion plating at a substrate temperature of 20° C., using iridium oxide as a dispersoid D11 and tin oxide as a dispersion medium D12. This electrode layer D1
contained 20% by weight of dispersoid D11 and had a sheet resistance of 500Ω/□. Next, a film with a thickness of 5000Å is deposited on top of it under the following conditions: Evaporation source: Ta ₂ O ₅ Degree of vacuum: 5 × 10 ^-6 Torr O ₂ Partial pressure: 4 × 10 ^-4 Torr Substrate temperature: 150°C A transparent ion conductive layer C was formed. Furthermore, under the following conditions: Evaporation source: WO ₃ Vacuum degree: 5 × 10 ^-6 Torr Ar partial pressure: 4 × 10 ^-4 Torr Substrate temperature: 150°C A transparent non-woven film with a thickness of 5000 Å was deposited under the following conditions: A crystalline WO ₃ -layer B was formed. Finally, apply the following conditions on top of WO ₃ (B): Evaporation source: mixture of In ₂ O ₃ and SnO ₂ Degree of vacuum: 5 × 10 ^-6 Torr Ar partial pressure: 3 × 10 ^-4 Torr Substrate temperature: 150°C The film thickness is increased by high-frequency ion plating under the
A transparent electrode layer A of 2500 Å was formed. In this way, an ECD having the structure shown in FIG. 1 was obtained. After sealing this ECD with epoxy resin, when a coloring voltage of 1.4 volts is applied between the first electrode layer A and the second electrode layer D1, a blue color develops in 400 msec, and the transmittance (Tc) at the time of coloring is λ=600nm
20%, and this coloring state was maintained even after the voltage application was stopped. Next, when a decoloring voltage of -1.4 volts was applied, the original colorless and transparent state was restored in 350 msec, and the transmittance (Tb) at the time of decolorization was 85%. (Example 2) The glass substrate S used in Example 1 was prepared, and the following conditions were applied on it: Evaporation source: Mixed sintered body of In ₂ O ₃ and SnO ₂ (ITO)
Composite target of Iridium and metal Ir Vacuum degree: 5 × 10 ^-6 Torr Ar partial pressure: 5 × 10 ^-3 Torr Substrate temperature: By high-frequency sputtering at room temperature, metallic iridium was made into a dispersoid D11, and In ₂ O ₃ and A second electrode layer D1 consisting of a transparent dispersion layer D1 having a thickness of about 500 Å was formed using a mixture with SnO ₂ as a dispersion medium D12. This electrode layer D1 contained 30% by weight of dispersoids D11 and had a sheet resistance of 150Ω/□. Hereinafter, as in Example 1, transparent ion conductive layer C,
A transmission type ECD was prepared by sequentially laminating _three WO layers B and a transparent first electrode layer A. After sealing with epoxy resin, a color development and fading test was performed, and it was +1.4V for 250msec, Tc = 25%, and -1.4V.
The time was 250 msec, and Tb = 75% (λ = 600 nm). (Comparative Example 1) A glass substrate S on which a transparent second electrode layer D made of ITO with a film thickness of 0.15 μm was formed was prepared, and the following conditions were applied on the electrode layer D: Evaporation source: metal Ir Vacuum degree: 5 ×10 ^-6 Torr Ar partial pressure: 3 × 10 ^-4 Torr The film thickness was
A transparent iridium oxide layer (D ₀ :containing no dispersion medium) of 700 Å was formed. After that, as in Example 1, layer C, layer B, and layer A are sequentially laminated to form a structure as shown in FIG.
An ECD was prepared and sealed in the same manner. The obtained ECD was colored slightly brown even before the coloring voltage was applied.
Even after applying a 0.5Hz alternating current voltage of ±1.5 volts for 500 minutes in the atmosphere, it did not become completely colorless and transparent. After decoloring, I performed a decolorization test and found that
At 150 msec, Tc was 15%, and at 100 msec, Tb was 50%. (High temperature durability test) Sealing created in Examples 1 and 2 and Comparative Example 1
ECD at 80℃, 200℃ after determining the contrast ratio.
The sample was subjected to a high-temperature durability test for several hours, and then the contrast ratio was determined. The results are shown in Table 1 below.
Note that the contrast ratio was determined as follows. Contrast ratio = log (T1/T2) T1 = Saturation transmittance when decolorizing (%) T2 = Saturation transmittance when coloring (%) Measurement wavelength λ = 600nm

[Table] (Effects of the Invention) As described above, according to the present invention, a colorless and transparent ECD with no coloration after production can be obtained, and there is extremely little decrease in contrast after the high temperature durability test.
ECD is obtained. Additionally, since the conventional iridium hydroxide layer is not required, the overall structure of the ECD is simplified. It also has the advantage of being cheaper because the amount of expensive iridium used is reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an ECD according to Example 1 of the present invention. 2A and 2B are schematic cross-sectional views of an ECD according to another embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a conventional ECD. Explanation of symbols of main parts, A...first electrode layer, B
...Reduced color forming EC layer, C...Transparent ion conductive layer,
D1...Transparent dispersion layer = second electrode layer of the present invention, D...
... Conventional second electrode layer, D ₀ ... Iridium hydroxide (oxide) layer, E... Third electrode layer.

Claims (1)

[Claims] 1. A first electrode layer, a reduction color-forming electrochromic layer adjacent to the electrode layer, and a second electrode layer adjacent to the electrochromic layer either directly or via a transparent ion conductive layer. In an electrochromic display device in which at least one of the first and second electrode layers is transparent, the second electrode layer is made of iridium metal itself or its oxide or hydroxide. a transparent dispersion layer formed of a dispersoid made of a conductive inorganic oxide and a transparent solid dispersion medium made of a conductive inorganic oxide, the dispersoid being dispersed in the transparent solid dispersion medium in an ultrafine state, and the transparent An electrochromic display device characterized in that the dispersion layer is formed by a vacuum thin film formation technique or a thick film method. 2. A transparent or reflective first electrode layer, a second electrode layer existing on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer, formed on the first electrode layer. In an electrochromic display device formed by laminating a reduction color forming electrochromic layer and a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer, the second electrode layer comprises: A transparent dispersion layer formed of a dispersoid made of iridium metal itself or its oxide or hydroxide and a transparent solid dispersion medium made of a conductive inorganic oxide, wherein the dispersoid is in the transparent solid dispersion medium. An electrochromic display device, characterized in that the transparent dispersion layer is dispersed in an extremely fine particle state, and the transparent dispersion layer is formed by a vacuum thin film formation technique or a thick film method. 3. A first electrode layer, a second electrode layer existing on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer, and a reduction color forming electrolyte formed on the first electrode layer. a chromic layer, a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer, and a third electrode layer formed on the ion conductive layer; In an electrochromic display device in which at least one of the first or third electrode layer is transparent, the second electrode layer is made of a conductive inorganic oxide and a dispersoid of iridium metal itself or its oxide or hydroxide. a transparent dispersion layer formed of a transparent solid dispersion medium, the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and the transparent dispersion layer is formed using a vacuum thin film forming technique or a thick An electrochromic display device characterized in that it is formed by a film method. 4 Laminated with a first electrode layer, a reduction color forming electrochromic layer adjacent to the electrode layer, and a second electrode layer adjacent to the electrochromic layer directly or via a transparent ion conductive layer, Further, in the electrochromic display device in which at least one of the first and second electrode layers is transparent, the second electrode layer comprises a dispersoid made of iridium metal itself or its oxide or hydroxide, and an inorganic fluoride. a transparent dispersion layer formed of a transparent solid dispersion medium made of a chemical compound, the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and the transparent dispersion layer is formed using a vacuum thin film forming technique. Or an electrochromic display device characterized in that it is formed by a thick film method. 5. A transparent or reflective first electrode layer, a second electrode layer existing on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer, formed on the first electrode layer. In an electrochromic display device formed by laminating a reduction color forming electrochromic layer and a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer, the second electrode layer comprises: A transparent dispersion layer formed of a dispersoid made of iridium metal itself or its oxide or hydroxide and a transparent solid dispersion medium made of an inorganic fluoride, the dispersoid being polarized in the transparent solid dispersion medium. An electrochromic display device characterized in that the transparent dispersion layer is dispersed in a fine particle state and is formed by a vacuum thin film formation technique or a thick film method. 6 a first electrode layer, a second electrode layer existing on the same or substantially the same plane as the electrode layer and insulated from the first electrode layer, a reduction color forming electrolyte formed on the first electrode layer; a chromic layer, a transparent ion conductive layer covering both the electrochromic layer and the second electrode layer, and a third electrode layer formed on the ion conductive layer; In an electrochromic display device in which at least one of the first or third electrode layer is transparent, the second electrode layer is transparent and made of a dispersoid made of iridium metal itself or its oxide or hydroxide and an inorganic fluoride. a transparent dispersion layer formed with a solid dispersion medium, the dispersoid is dispersed in the transparent solid dispersion medium in the form of extremely fine particles, and the transparent dispersion layer is formed using a vacuum thin film forming technique or a thick film method. An electrochromic display device characterized in that it is formed by.