JP2569439B2 - Manufacturing method of reflective electrochromic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel method for manufacturing a reflective electrochromic device.

[Conventional technology]

A phenomenon in which a voltage is applied to cause a reversible electrolytic oxidation or reduction reaction to cause reversible coloring (color development) is called electrochromism. An EC element (hereinafter, referred to as EC) (hereinafter, referred to as EC) which sandwiches a thin film of an electrochromic (hereinafter abbreviated as EC) material exhibiting such a phenomenon between a pair of electrode layers and controls the voltage applied between the electrode layers. ECD)
Attempts to use this ECD for a light quantity control element (for example, an anti-glare mirror) or a numerical display element using 7 segments have been made for more than 20 years.

For example, an ECD (see Japanese Patent Publication No. 52-46098) in which a transparent electrode layer, a tungsten trioxide thin film, and an insulating film (for example, silicon dioxide) are laminated on a glass substrate is known as an all-solid-state ECD. When this ECD to apply the coloring voltage V _C tungsten trioxide (WO ₃₎ thin film is colored blue. Thereafter, when a decoloring voltage Vb of the opposite polarity is applied to this ECD, the blue color of the WO ₃ thin film disappears and the WO3 thin film becomes colorless.

Although the mechanism of coloring and decoloring is not elucidated in detail, it is understood that a small amount of water contained in the WO ₃ thin film and the insulating film (ion conductive layer) controls the coloring and decoloring of WO _3. ing. The coloring reaction formula is estimated as follows.

^{_{H 2 O → H + + OH}} - (WO 3 film = ^{_{cathode) WO 3 + nH + + ne}} - → HnWO 3 colorless blue (insulating film = _{^{anode) 2OH - → H 2 O +}} 1/2 O 2 ↑ e - or of formula As will be understood from WO, WO ₃ is a reduced coloring EC substance that is colored by reduction. In addition to WO _3, M ₀ O ₃ also is the case.

By the way, an oxidation reaction accompanying reduction is inevitable. In this case, an oxidation reaction of 2OH ⁻ → H ₂ O + 1 / 2O ₂ ↑ + e ⁻ occurs in the ECD system. Therefore, this kind of ECD
Disadvantages are that, during the coloring reaction, the contained water is consumed by an undesired side reaction of oxygen gas generation, and water is not generated by the reverse decoloring reaction. Supply is necessary.
In particular, for the latter reason, this type of ECD has the disadvantage that the reproducibility of the coloring is influenced by atmospheric moisture.

Therefore, recently, the same amount of water as the amount of water consumed by the coloring reaction is generated by the decoloring reaction, and therefore, the coloring and decoloring can be repeated without the need to reinforce the moisture from the outside, and the repetition is also possible. An all-solid-state ECD in which the coloring density is not affected by the external environment has been proposed (see JP-A-52-73749 and JP-A-56-4679).

A typical structure of the proposed ECD is as follows.

A: Electrode layer B: Reduction coloring EC layer such as WO ₃ , M ₀ O ₃ C: Ion conductive layer such as SiO ₂ , Ta ₂ O ₅ D: Oxidation coloring EC layer such as Cr ₂ O ₃ , IrOx, Ir (OH ) YE: Electrode layer It goes without saying that at least one of the electrode layers A and E must be transparent. One may also serve as the reflective layer.

And iridium hydroxide Ir as an oxidation coloring EC substance
(OH) y (Iridium hydroxide, like a common hydroxide, can also be viewed as a hydrate of iridium oxide IrOx. Thus, in this specification, iridium oxide,
When expressed as iridium oxide, iridium oxide, IrOx, etc., it is to be understood that the term refers to a hydroxide or a mixture with a hydroxide in some cases). Was the best of the ECDs reported.

In this case, the method of manufacturing the iridium hydroxide thin film as the oxidative coloring EC layer includes once forming a metal iridium thin film by a vacuum thin film deposition technique such as vacuum deposition, sputtering, or ion plating, and then using sulfuric acid or the like in the next step. A thin film of iridium oxide by anodic oxidation in an electrolytic solution (for example, JP-A-56-4679).
And a method of performing reactive sputtering in an oxygen atmosphere using a metal iridium as a target to directly obtain an iridium oxide thin film in one step (for example, see US Pat. No. 4,258,984). electrode layer B: reductive coloring EC layer C: a transparent ion conductive layer D _0: iridium thin film E: manufactured five-layer structure of the electrode layer (ECD precursor), in a gas atmosphere containing water vapor in the next step, electrodes a, D ₀ layer by applying an alternating current between E method of changing the oxide or hydroxide iridium (iridium) (see, for example, JP-a-58-70215) 3
The street has been reported.

However, in any case, the D layer: iridium oxide or hydroxide is composed of a single component of iridium oxide or hydroxide, and the ECD of JP-A-56-4679 using this is
There was a disadvantage that the high-temperature durability was poor.

Therefore, an ECD that solves this drawback has been invented (see JP-A-60-222827). This ECD is disclosed in JP-A-56-4679.
Has a generally five-layer structure similar to the ECD of No., characteristic that is not a oxidative coloring EC layer is pure oxide or iridium hydroxide, therewith to consist dispersion of a dispersion medium for example SnO ₂ It is.

According to the method disclosed in JP-A-60-22287, a dispersion layer comprising a metal iridium thin film and a dispersion medium is once formed, and then, in the next step, (i) thermal oxidation or (Ii) oxidizing metal iridium by anodic oxidation,
A method of changing to a dispersion layer composed of iridium oxide or hydroxide and a dispersion medium, using two kinds of iridium oxide and a dispersion medium as an evaporation source or a target, and directly using a vacuum thin film deposition technique (non-reactive system) in one step. To obtain a dispersion layer,
And a method of directly obtaining a dispersion layer in one step by a vacuum thin film deposition technique (reaction system) under an oxygen atmosphere using two kinds of metal iridium and a dispersion medium as an evaporation source or a target.

In each case, the iridium oxide or hydroxide is dispersed in the dispersion at the molecular level or as a mass of ultrafine particles.

However, (i) the production method by thermal oxidation has a problem that the oxidation of metal iridium does not proceed completely, and therefore, the transparency of the dispersion layer is insufficient and only a gray color can be obtained.

(Ii) The production method by anodic oxidation has a wet process called anodic oxidation (the other processes can be done by dry process)
There is a problem that the production efficiency of D is greatly reduced and the cost is high.

The production method using iridium oxide as a target for the evaporation source is problematic in that the production of the evaporation source and the target is difficult and impractical, and bumping occurs during the production, causing the dispersion layer to have a lump. Has the problem that

The production method using the reaction-based deposition technique described above has a problem that the obtained ECD has a small change width of coloration and decoloration and a problem that the reproducibility is poor and the performance varies between lots.

Therefore, the present inventors have conducted intensive research and found that a five-layer structure in which a “dispersion layer D _{0 made of} metal iridium (dispersoid) and a dispersion medium” is laminated instead of the D layer by accident. A laminate is made, and between the electrode layers A and E of the laminate, by applying an AC voltage in a gas atmosphere containing oxygen gas or water vapor, the iridium metal in the D ₀ layer is converted into oxidized or iridium hydroxide. In other words, A: an electrode layer B: a reduced color-forming EC layer C: an ion conductive layer D ₀ : a dispersion layer composed of iridium oxide or hydroxide (dispersoid) and a dispersion medium E: a five-layer structure composed of an electrode layer An ECD was obtained. Although the ECD had the same composition and structure as that of Japanese Patent Application Laid-Open No. 60-22287, it was mysteriously found that it did not have the above-mentioned problems. (63-454).

That is, in the prior invention, an AC voltage was applied between the electrodes A and E of the five-layered structure including the D ₀ layer in an atmosphere of oxygen gas or water vapor to apply iridium in the D ₀ layer. By converting the metal to iridium oxide or iridium hydroxide,
This is an invention for producing an ECD having a five-layer structure including layers.

[Problems to be solved by the invention]

However, when manufacturing a reflection type ECD in which one of the electrodes A and E is a transparent electrode layer and the other is a reflective metal electrode layer, the manufacturing method of the embodiment specifically disclosed in the specification of the prior invention is required. In the method (the starting material is the one having the structure shown in FIG. 2 attached to the present specification), as a result of subsequent research, it takes a long time to manufacture, and when the manufactured ECD is colored, coloring unevenness occurs. It has been found that there is a problem that it easily occurs.

Accordingly, an object of the present invention is to provide a novel method of manufacturing a reflective ECD that does not have these problems.

[Means for solving the problem]

The present inventors happened to change the laminating order and use a five-layer structure in which a D ₀ layer: a layer containing iridium metal or a lower oxide thereof is arranged so as to be in contact with the reflective metal electrode layer as a starting material. As a result, it has been found that the above-mentioned object is achieved, and the present invention has been accomplished.

Therefore, the present invention provides, in order from the top, A: a reflective metal electrode layer D ₀ : a layer containing iridium metal or a lower oxide thereof C: an ion conductive layer B: a reduced color-forming electrochromic layer E: a transparent electrode layer S: By applying an AC voltage in a gas atmosphere containing oxygen or water vapor between the electrode layers A and E of a laminate having a five-layer structure of a transparent substrate, the iridium metal or its lower oxide of the D ₀ layer is Provided is a method for manufacturing a reflection-type electrochromic device, which is characterized by being oxidized or converted to a higher oxide.

(Operation)

As in the present invention, when D ₀ : a layer containing iridium metal or a lower oxide thereof, A: a five-layer laminate adjacent to the reflective metal electrode layer is used as a starting material, the reason why oxidation of iridium is easy to proceed is as follows. Is estimated as follows.

When the electrode layer adjacent to (i) D ₀ is a transparent electrode as in the embodiment of the prior invention (second aspect view) (E), which is relatively high electric resistance, the electrode extraction portion of it When an AC voltage is applied by connecting the external wiring (F), a voltage gradient is generated in the transparent electrode layer (E), and as a result, a sufficient amount of voltage is generated in a portion near the extraction portion of the transparent electrode layer (E). since positive charges are supplied, iridium metal or proceeds faster oxidation of D ₀ layer their lower oxides, oxides having an EC property (hydroxide optionally as described above) or a higher oxide (described above As the case may be.

Although D ₀ layer exhibits a considerable opaque gray metal reflection color, at the oxide or higher oxides, becomes colorless and transparent, the thickness increased to approximately 5 times.

As a result, when further positive charges are supplied, the iridium is in a higher oxidation state, the layer exhibits a transparent gray (having no reflection color), and the layer changes color to a colorless transparent transparent gray upon application of an AC voltage. repeat. This is EC property.

However, since a sufficient amount of charge in the portion far from the take-out portion is not supplied, taken, oxidation of D ₀ layer is slow.

Therefore, not only does it take time until the entire _D0 layer becomes an oxide or a higher oxide, but also a portion that is not locally oxidized remains, causing coloring unevenness.

Further, it is difficult to form the transparent electrode layer (E) to have a uniform resistance value as a whole, and this is also considered to cause coloring unevenness.

(B) oxygen or moisture oxidizes the D ₀ layer is thought to come through the metal electrode layer from the outside (A), D ₀ layers, A / B / C / D 0 / E / S laminate substrate When it is inside, external oxygen or moisture must come through the three layers of A / B / C, so that a sufficient amount of oxygen or moisture is not supplied to the _D0 layer and oxidation occurs. It will be difficult to proceed. Incidentally, oxygen or moisture is not supplied from the S substrate side.

On the other hand, as in the present invention, the D ₀ layer has A / D ₀ / C / B / E
In the / S substrate laminate, external oxygen or moisture only needs to pass through one layer A, so that it is easy to pass, and therefore oxidation is easy to proceed.

(C) When the D ₀ layer is oxidized, the film thickness expands to about 5 times. When the D ₀ layer is in the laminate of the A / B / C / D ₀ / E / S substrate,
D ₀ layer attached suppressed to A / B / C3 layer, since hardly expanded, hardly proceeds oxide.

On the other hand, as in the present invention, the D ₀ layer has A / D ₀ / C / B / E
In the laminate of the / S substrate, there is only one layer A on the _D0 layer, so that it easily expands, and therefore oxidation is apt to proceed.

As the transparent substrate (S) on which the transparent electrode layer (E) is laminated, for example, a tough and transparent material such as glass, ceramics, or plastics is used.

The materials constituting the transparent electrode layer (E) include tin oxide (SnO ₂ ), ITO (indium oxide mixed with about 5% of SnO _2- good transparency), indium oxide (In
₂ O ₃ ), copper iodide, zinc oxide and the like are used.

As a material constituting the metal electrode layer (A), for example, chromium, tin, zinc, nickel, gold, platinum, palladium,
Rhodium, aluminum, silver and the like are used.

The thickness of the electrode layers (A) and (E) is sufficient to be 0.01 to 0.5 μm, but may be thicker if desired.

Examples of the reduced color-forming EC layer of the B layer include tungsten trioxide, molybdenum trioxide and the like, and among them, tungsten trioxide is preferable.

As the ion conductive layer of the C layer, a liquid electrolyte, for example, an acid such as sulfuric acid or hydrochloric acid or its water solubility, an aqueous solution of an alkali such as sodium hydroxide or potassium hydroxide, sodium chloride, lithium chloride, lithium chloride, An aqueous solution of a solid strong electrolyte such as lithium sulfate.

Semi-solid gel electrolyte: for example, an aqueous electrolyte solution gelled with a gelling agent such as polyvinyl alcohol, CMC, agar, or gelatin.

Solid electrolyte: For example, HVP, β-Al ₂ O ₃ , Na ₃ Zr ₂ Si ₂ PO
Such as _{12, Na 1 + Z Zr 2} Si X P 3-X O 12, Na 5 YSi 4 O 12, RbAg 4 I 5.

Water or ion-containing synthetic resin solid: for example, a water-containing vinyl polymer such as a copolymer of β-hydroxyethyl methacrylate and 2-acrylamido-2-methylpropanesulfonic acid, a water-containing methyl methacrylate copolymer, and a water-containing polyester Such.

Others: Tantalum oxide (Ta ₂ O ₅ ), niobium oxide (Nb ₂
O ₅ ), zirconium oxide (ZrO ₂ ), titanium oxide (Ti
O 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. These materials are insulators for electrons, but are good conductors for protons (H ⁺ ) and hydroxy ions (OH ⁻ ).

The C layer is present in a form sandwiched between the B layer and the D ₀ layer in the case of a liquid or semi-solid gel, but in the case of water or an ion-containing synthetic resin solid, the adhesive layer of the B layer and the D ₀ is used. This method may be combined, and this method is described in detail in the specification of Japanese Patent Application No. 56-98404 of the present applicant. In this case, the thickness of the C layer is about 0.1 to 1000
μm is sufficient.

It is preferable to use a so-called solid insulator for the purpose of reducing the thickness of the C layer or solving the problem of liquid leakage. In this case, the thickness can be reduced to 0.001 to 10 μm.

 The C layer must be as transparent as possible.

D ₀ layer is a layer containing an iridium metal or a lower oxide. This layer may be a dispersion in which the dispersoid is metal iridium or its lower oxide, which is dispersed in a dispersion medium. As a dispersion medium, for example, SnO ₂ , InO ₃ , ITO, Zno
Such as transparent conductive inorganic oxides, Ta ₂ O ₅ , TiO ₂ , SiO ₂ , WO ₃ ,
Transparent inorganic oxides such as MoO ₃ and Sb ₂ O ₃ and transparent inorganic fluorides such as MgF ₂ and CaF ₂ are used. Among these, Sn
O ₂ , In ₂ O ₃ , ITO, Zno and Ta ₂ O ₅ are preferred.

The dispersoid preferably contains 15 to 60% by weight, particularly 15 to 25% by weight of Ir metal or its lower oxide in the dispersion.

Here, the relationship between the dispersoid and the dispersion medium may be reversed, and the dispersion layer (D ₀ ) can be regarded as a mixture. What is important is that Ir metal as a dispersoid is dispersed at an atomic level or in an ultrafine particle state.

Such a dispersion layer (D ₀ ) is made by a vacuum thin film deposition technique.

The thickness of the D ₀ layer is the same layer B, usually 0.001 number μ
m is sufficient.

The layers A to E are formed by a vacuum thin film deposition technique, for example, vacuum evaporation or sputtering, unless the layer C is a liquid, a semi-solid gel, or a synthetic resin.

Further, when it is desired to display in a pattern, at least one layer may be patterned except for the C layer, or a patterned light-shielding layer or an electron / ion insulating layer may be provided on any interlayer or layer. You may.

A~E layer prepared in advance and whether or A-D ₀ laminate laminated in this order and B-E laminate A~E Depending on the choice of C layer, a method of sandwiching the C layer in both, A laminate having a five-layer structure as a starting material is obtained.

In the present invention, the laminate is placed in a gas atmosphere containing oxygen gas or water vapor, for example, in the air, and an AC voltage is applied between the electrode layers AE. The alternating current frequency of about 0.01 to 10 Hz is sufficient, and the waveform may be any of a triangular wave, a rectangular wave, a sawtooth wave, and a sine wave. When the voltage is an AC voltage is applied is sufficient 0.5-3 volts position, Ir metal D ₀ layer reacts with oxygen or moisture from the atmosphere, or other layers in the oxide or hydroxide gradually metallic color omission As it becomes an object, it becomes transparent and eventually shows electrochromism.

Thus, an ECD having a high contrast ratio is obtained.

ADVANTAGE OF THE INVENTION According to this invention, compared with the method of carrying out electrolytic oxidation in an acid or alkali aqueous solution, manufacturing equipment and process are simplified, and a drastic reduction in manufacturing cost is expected.

The ECD manufactured according to the present invention can change the reflectance at a low voltage and is useful as a mirror having a variable reflectance. For example, it is useful as an anti-glare mirror for an automobile.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

〔Example〕

(1) A glass substrate (S) having a length of 8 cm × a width of 15 cm × a thickness of 2 mm on which an ITO transparent electrode layer (E) having a thickness of 0.15 μm was formed was prepared.

(2) The substrate was set in an electron beam heating vacuum vapor deposition apparatus in which WO ₃ was arranged as an evaporation source, and a vacuum vapor deposition method (vacuum degree: 1 to 2 × 10 ⁻⁴ Torr, vapor deposition rate: 5 to 10 × 10 ⁻⁴ μm / sec), a reduced color-forming EC layer (B) made of tungsten trioxide having a thickness of 0.25 μm was formed. (3) Subsequently, a vacuum deposition method (vacuum degree: 1 to 2 × 10 ⁻⁴ Torr, deposition rate:
A transparent ion conductive layer (C) made of tantalum pentoxide having a thickness of 0.25 μm was formed at 3 × 10 ⁻⁴ μm / sec).

(4) Ir metal and tin oxide are set as the evaporation source (binary), and the degree of vacuum is 1 to 5 with the same electron beam heating vacuum evaporation apparatus.
Vacuum deposition (non-reactive) was performed under the conditions of × 10 ^-5 Torr, deposition rate: 10Å / sec, and a 700Å thick dispersion layer (D
₀ ) was formed.

When this dispersion layer (D ₀ ) was analyzed, it was found that the dispersion layer was 10
It contained 20% of Ir metal as 0% by weight.

(5) Finally, a reflective Al electrode layer (A) having a thickness of 1000 mm is formed on the D ₀ layer by vacuum evaporation under the conditions of evaporation source: Al, vacuum degree: 5 × 10 ⁻⁶ Torr, substrate temperature: room temperature. I let it.

(6) Between the electrode layers A and E of the laminate having a five-layer structure (see FIG. 1) obtained in this manner, ± 1.
35V, by applying 1 to 2 hours AC voltage cycle 0.05 Hz, instead of oxides of Ir metal ₀ layer in D, to produce a reflective ECD a five-layer structure.

(Comparative example)

In the example, the steps (2) and (4) were interchanged to produce a five-layered laminate (see FIG. 2).

Between the electrode layers AE of the obtained laminate (see FIG. 2)
By applying an AC voltage of ± 1.35 V and a cycle of 0.05 Hz through the external wiring (F), the Ir metal in the D ₀ layer was changed to an oxide, and a reflective ECD having a five-layer structure was manufactured. At this time, D ₀
It took 10 hours for the layer to become oxide.

(Test example)

The ECDs manufactured in the above Examples and Comparative Examples were sealed by bonding a sealing glass substrate using an epoxy resin (sealant / adhesive), and then subjected to the following test.

Coloring / Decoloring Test When a coloring voltage of +1.35 V is continuously applied between the electrode layers A and E of the ECDs of the examples and the comparative examples, the reflectance sharply decreases, and about 1
Saturated at 0 seconds. This state was maintained even when the voltage application was stopped. However, coloring unevenness was observed in the ECD of the comparative example.

Then, when the decoloring voltage of -1.35 V was continuously applied, the reflectance rapidly recovered and was saturated in about 10 seconds. However, the comparative ECD
Had uneven coloring.

The reflectance was measured at the center position of the ECD using monochromatic light having a wavelength λ = 600 nm.

Therefore, for each ECD, coloring voltage + 1.35V was applied 10 seconds was measured in the same manner the reflectance R _c, then the decoloring voltage -1.35 V 1
Applying 0 seconds, the reflectance _Rb was measured similarly. The results are shown in Table 1 below.

[Effects of the Invention] As described above, the present invention has an effect that the production time (time of oxidation in the atmosphere) is shorter than that of the prior invention, and uneven coloring and erasing hardly occurs.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a cross-sectional structure of a five-layered laminate as an example of a starting material (precursor) used in the production method of the present invention. FIG. 2 is a conceptual diagram illustrating a cross-sectional structure of a laminate as a starting material (precursor) used in an example of the prior application invention. [Description of Signs of Main Parts] A: Reflective metal electrode layer D _0: Layer containing iridium metal or its lower oxide C: Ion conductive layer B: Reduction color-forming electrochromic layer E: Transparent electrode Layer S: Transparent substrate

Claims (1)

(57) [Claims] 1. In order from the top, A: reflective metal electrode layer D ₀ : layer containing iridium metal or its lower oxide C: ionic conductive layer B: reduction electrochromic electrochromic layer E: transparent electrode layer S: transparent By applying an alternating voltage between the electrode layers A and E of the laminate having a five-layer structure of the substrate in a gas atmosphere containing oxygen or water vapor, the iridium metal or its lower oxide of the D ₀ layer is oxidized. A method for producing a reflection-type electrochromic device, characterized in that the reflection-type electrochromic device is converted into a material or a higher oxide.