JPH0652356B2 - Electrochromic device with transparent electrode as extraction part - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a novel electrochromic device (hereinafter, “electrochromic” is abbreviated as “EC”, and an EC device is referred to as “EC”).
Abbreviated as D).

BACKGROUND OF THE INVENTION ECDs generally consist of a pair of electrode layers, at least one of which is transparent, and an EC layer sandwiched therebetween.
This ECD develops color when a voltage as large as that obtained from a dry cell is applied between a pair of electrodes, and disappears when a reverse voltage is applied and returns to the original colorless and transparent. Therefore, the ECD has been actively researched for use in display devices, particularly numeric display devices using a letter-shaped seven segment, a control device for the amount of transmitted or reflected light, and the like.

In order for EC material such as WO ₃ to develop color, simultaneous injection of electrons (e ⁻ ) and cations (X ⁺ ) is required, and the reaction formulas associated with color development and decolorization are believed to be as follows.

Decolored state: WO ₃ + ne ⁻ + nX ⁺ ↑ ↓ Colored state: XnWO ₃ And, as the cation (X ⁺ ), H ⁺ and Li ⁺ having a small ionic radius and easy to move are mainly used. The cation (X ⁺ ) does not have to be a cation at all times, and cations may be generated when a voltage is applied and an electric field is formed. Therefore, in the case of H ⁺ , water is used as a cation supply source. A very small amount of water seems to be sufficient, and when the ECD is exposed to the atmosphere, it is often sufficient that the water naturally enters the layer from the atmosphere.

However, even if the WO ₃ layer is sandwiched between a pair of electrodes and a voltage is applied to develop a color, the color cannot be easily erased. Because electrons (e ⁻ ) flow in from the electrode side in contact with the cathode even if a reverse voltage is applied in an attempt to erase the color, so if H ⁺ exists, WO ₃ + ne ⁻ + nH ⁺ → HnWO ₃ This is because the reaction occurs and color develops.

Therefore, S. K. Deb et al., An EC in which an insulating layer such as SiO ₂ or MgF ₂ is provided between the WO ₃ layer and one electrode.
Proposed D (Japanese Patent Publication No. 52-46098). This insulating layer is
According to the research by the present inventor, electrons cannot move, but H
⁺ And OH ^- the movement of ions such as a free, this H
⁺ And OH ⁻ ions carry electricity (in this sense, it is incorrect to call it an insulating layer and it is correct to call it an ion conductive layer), and OH ⁻
It is considered that the ions react at the interface with the anode according to the reaction formula of OH ⁻ → 1 / 2H ₂ O + 1 / 4O ₂ ↑ + e ⁻ and emit electrons to the anode side.

In other words, during color development, the cathode side is WO ₃ + ne ⁻ + nH ⁺ → HnWO ₃ Anode side: nOH ⁻ → n / 2H ₂ O + n / 4O ₂ ↑ + ne ⁻ Reaction is presumed, and when decoloring, the anode side: HnWO ₃ → WO ₃ + ne ⁻ + nH ⁺ cathode side: nH ₂ O + ne ⁻ → nOH ⁻ + n / 2H ₂ ↑ It is estimated that the reaction occurs.

As is clear from these equations, in reality, S. K. D
In ECD of eb et al., water is consumed by driving for coloring and decoloring, so if water is not rapidly supplied from the atmosphere, color does not develop, and O ₂ and H ₂ gas are released along with driving, so that the interlayer There is a drawback that peeling occurs.

Therefore, Y. Takahashi et al. Proposed an ECD in which an oxidative coloring EC layer is provided between an ionic conductive layer and an electrode layer (JP-A-56-4679). This ECD uses, for example, iridium hydroxide as an oxidation coloring EC layer.
At the time of color development of ₃ , mainly on the anode side, colorless and transparent: Ir (OH) m + n (OH ⁻ ) ↓ Coloring: Ir (OH) p · qH ₂ O + rH ₂ O + S
It reacts with (e ⁻ ), and when WO ₃ is decolored, Ir (OH) p · qH ₂ O + rH ₂ O + S is mainly formed on the cathode side.
(E ⁻ ) ↓ Ir (OH) m + n (OH ⁻ ) It is presumed that it reacts with. Therefore, since the water is regenerated, the water is not consumed and is not consumed, and the O ₂ and H ₂ gases are not released along with the driving.

In addition, there are a combination of an EC layer and a lithium solid electrolyte layer, and a combination of an EC layer and a proton-containing or proton-releasing solid or semi-solid resin layer.

In any case, from the viewpoint of reliability and durability of ECD, ECD
Need to be sealed. Particularly in the case of an ECD that uses water as a proton supply source, it is necessary to seal it in order to prevent water from escaping. Epoxy resin and other resins are generally used for sealing.

By the way, when the ECD is sealed, since driving power must be supplied to the pair of electrode layers, a part (called a take-out portion) of each is exposed from the sealing region, and wiring from the outside is bonded thereto. To do.

However, the ECD sealed with a metal thin film, for example, an Al thin film, as an electrode layer of the ECD has a problem that the exposed extraction portion is separated from the substrate in a relatively short time as a result of the hot water resistance test. It has been found.

(Object of the Invention) Therefore, an object of the present invention is to provide a sealed ECD,
An object is to solve the problem that the “extraction part made of a metal thin film” exposed from the sealing region has poor hot water resistance and is peeled off from the substrate in a relatively short time.

(Summary of the Invention) As a result of experiments, the present inventor has found that a conductive oxide transparent thin film that is commonly used as a transparent electrode, such as SnO ₂ or In _{2, is used.}
O ₃ , ITO (a mixture of SnO ₂ and In ₂ O ₃ )
Knowing that it is excellent in hot water resistance, this transparent electrode was used as the extraction electrode of the metal thin film electrode layer, and it was conceived to expose a part of it to the outside of the sealing region as a new extraction part, and to form the present invention. I arrived.

Therefore, the present invention provides a pair of electrode layers (A), one of which is a metal thin film (A) and the other of which is a conductive oxide transparent thin film (B).
At least 3 of (B) and electrochromic layer (F)
In the electrochromic device consisting of the requirements, the extraction part of the metal thin film (A) is connected to one end of the extraction electrode (C) composed of a conductive oxide thin film in the sealing region,
An electrochromic device having the other end exposed outside the sealing region.

The extraction electrode (C) made of a transparent conductive oxide thin film used in the present invention includes SnO ₂ , In as described above.
₂ O ₃ , ITO, etc. may be mentioned. These electrodes (C)
Generally, it is formed on a substrate such as glass, plastic or ceramics by a vacuum thin film forming technique such as vacuum deposition, reactive deposition, ion plating, reactive ion plating or sputtering. In some cases, it may be formed by a thick film method (application of a solution of an organometallic compound such as a metal alcoholate or an oligomer thereof and baking to form a film).

The thickness of the electrode (C) depends on the resistance, but in general
It is 0.01 to 0.5 μm.

The transparent electrode layer (B) is also made in the same manner as the extraction electrode (C). The electrode layer (B) and the electrode (C) are preferably provided on the same substrate in consideration of wiring from the outside.

Therefore, in order to reduce the number of steps, the electrode (B),
It is preferable to form (C) at the same time and simply perform patterning so that both may not be short-circuited.

As the metal thin film of the other electrode layer (A), for example,
Al, Ag, Ni, Pt, Au, Pd, Cr, Ir, R
u, Rh, etc. are used. Although the film thickness of the electrode (A) is not particularly limited, it is suitable to be about 8 × 10 ^-5 to 10 ^-1 mm. Electrode (A) is generally vacuum deposited, reactive deposited,
Ion plating, reactive ion plating,
It is formed by a vacuum thin film forming technique such as sputtering.

A reduction coloring EC layer is mainly used as the EC layer. As already known, amorphous WO ₃ or MoO ₃ is used for this reduction color-developing EC layer. These EC
The layer is generally formed by a vacuum thin film forming technique to a thickness of 0.01 to several μm.

In some cases, the ion conductive layer that may be provided is an insulator for electrons but a good conductor for protons (H ⁺ ) and hydroxy ions (OH ⁻ ). This is provided as necessary in order to give the ECD of the present invention a memory property, that is, a property that the colored state is maintained even after the voltage application is stopped after the color is developed. The following is exemplified.

Inorganic dielectric thin film such as tantalum oxide (Ta ₂ O ₅ ), 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 (these substances are insulators against electrons, but protons (H ⁺ ) and hydroxy ions (OH
^- ) Is a good conductor. ) All solid type ECD
In particular, the thin film type ECD has the advantage that the thickness can be made extremely thin and there is no fear of liquid leakage. In that case, it is preferable to select this inorganic dielectric material as the ion conductive layer; sodium chloride, potassium chloride. , Sodium bromide, potassium bromide, Na ₃ Zr ₂ Si ₂ PO ₁₂ , Na ₁ + xZrSixP ₃ −xO ₁₂ , Na
Solid electrolytes such as ₅ YSi ₄ O ₁₂ and RbAg ₄ I ₅ ; synthetic resins containing water or a proton source, such as β-hydroxyethyl methacrylate and 2-acrylamido-2-
Copolymers with methylpropanesulfonic acid, hydrous vinyl polymers such as hydrous methyl methacrylate copolymers, hydrous polyesters, etc .; electrolytes, such as sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, butyric acid, oxalic acid Or an aqueous solution thereof, an aqueous alkali solution such as sodium hydroxide or potassium hydroxide, an aqueous solution of a solid strong electrolyte such as sodium chloride, lithium chloride, potassium chloride or lithium sulfate; a semi-solid gel electrolyte, for example, an aqueous electrolyte solution as a gelling agent. Examples thereof include those gelled with polyvinyl alcohol, CMC, agar, gelatin and the like.

Therefore, the ion conductive layer is formed by vacuum thin film forming technology, thick film method,
It is formed by encapsulation, injection, coating, and other means, and its thickness varies from 0.01 μm to 1 mm depending on the material.

If desired, an oxidatively coloring EC layer or a reversible electrolytically oxidizable layer or a catalyst layer may be used, for example, iridium oxide or hydroxide, nickel, chromium, vanadium, ruthenium, rhodium, etc. Can be given. These substances may be dispersed in another transparent ionic conductor layer or transparent electrode.

Hereinafter, the present invention will be described in detail with reference to examples.

(Embodiment) FIG. 1 is a sectional view of an ECD of the embodiment.
2A (plan view) and 2B (2A)
(A sectional view taken along the line A in the figure).

(1) An ITO film was formed on a glass substrate (S) and then patterned by photo-etching to form an electrode layer (B) and an extraction electrode (C) (Figs. 2A (1) and 2B).
(See (1)). Instead of photo etching, master vapor deposition may be performed from the beginning and patterning may be performed.

(2) Next, an iridium tin oxide monoxide mixed layer (D), a tantalum oxide layer (E) and a tungsten oxide layer (F) were sequentially laminated (see FIGS. 2A (2) and 2B (2)).

(3) An Al electrode (A) was formed thereon (see FIGS. 2A (3) and 2B (3)). In this case, a part of the Al electrode (A) is brought into contact with one end of the extraction electrode (C) already formed.

(4) Finally, except for the part that touches the outer edge of the extraction electrode (C) and the part that touches the outer edge of the electrode (B), seal with epoxy resin (R), and at the same time, cover the glass substrate (S )
An ECD was prepared by bonding a smaller protective glass plate (G) (see FIG. 1).

In addition, the manufacturing method and manufacturing conditions of each layer or each film are as follows.
Shown in the table.

ECD thus produced is the exposed to the sealing region (R) outside a part of the part and the ITO electrodes of the ITO electrode (C) (B), there are external wiring (L _A) , by bonding the _{(L B),} the driving power source (S
When a coloring voltage (+ 1.35V) is applied from u), the reflectance is reduced to 15% (after 1 second) for the light (L) with a wavelength of 633 mm that is incident from the substrate (S) side, and this reflectance is Even if the voltage application was stopped, it was maintained for a while. This time the erasing voltage (-
When 1.35 V) was applied, the reflectance also recovered to 65% (after 1 second).

This ECD was immersed in warm water at 70 ° C for 100 hours,
The electrodes (B) and (C) did not peel off from the substrate (S) and showed almost the same performance.

(Comparative Example) An ITO film was formed on the glass substrate (S) in the same manner as in Example 1 and patterned by photoetching to form only the electrode layer (B).

Hereinafter, in the same manner as in Example 1, (D), (E), (F) Layers are laminated in order, and finally Al electrode (A) is evaporated to form Al
Except for a part of the electrode (A) and a part of the electrode (B), the electrode was sealed with an epoxy resin (R) and a protective glass plate was adhered.
When external wiring is bonded to the exposed portions of the electrodes (A) and (B) of the obtained ECD (see FIG. 4) and driving is performed by applying a coloring / decoloring voltage, it is almost the same as the ECD of Example 1. It showed equivalent performance.

However, when this ECD was immersed in hot water at 70 ° C. for 100 hours, the Al electrode (A) exposed from the sealing region (R) was peeled off from the substrate (S) and was cut off, resulting in an external power supply. Power to the ECD has become impossible.

(Effects of the Invention) As described above, according to the present invention, E using a metal thin film electrode is used.
In the CD, the extraction electrode made of a conductive oxide transparent thin film was attached to the electrode, and the entire extraction electrode was sealed except for a part thereof, so that the metal thin film electrode was exposed outside the sealing region. Therefore, the problem that the electrode lead-out portion is separated from the substrate after the hot water resistance test is solved.

[Brief description of drawings]

FIG. 1 is a sectional view of an ECD according to an embodiment of the present invention. FIG. 2A is a plan view in each step of manufacturing the ECD of FIG. 1, and FIG. 2B is an end view taken along line A of FIG. 2A. FIG. 3 is an explanatory diagram showing a state in which a drive system is wired to the ECD of FIG. FIG. 4 is a sectional view of a conventional ECD. [Explanation of Signs of Main Parts] A ... Metal thin film and electrode layer made of it B ... Electroconductive transparent thin film and electrode layer made of it C ... Extracting electrode F ... EC layer R ... Epoxy resin and sealing region

Claims (3)

[Claims] 1. A pair of electrode layers (A) and (B), one of which is a metal thin film (A) and the other of which is a transparent conductive oxide thin film (B), and at least three requirements of an electrochromic layer (F). In the electrochromic element, the extraction part of the metal thin film (A) is connected to one end of the extraction electrode (C) made of a conductive oxide thin film in the sealing region, and the other end is exposed outside the sealing region. Electrochromic device characterized by 2. The electrochromic device according to claim 1, wherein the electrode layer (B) and the extraction electrode (C) are formed on the same substrate without short-circuiting. 3. The electro device according to claim 2, wherein the electrode layer (B) and the extraction electrode (C) are simultaneously formed in the same step.