JPH0443251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an all-solid-state thin film stacked electrochromic device (hereinafter referred to as "ECD"), and more particularly to an ECD using an oxidized coloring layer with improved transparency.

ECDs can be applied to, for example, numeric display elements, X-Y matrix display elements, optical shutters, aperture mechanisms, etc. For example, an ECD with an all-solid thin film laminated structure shown in FIG. 1 is known. That is, the ECD shown in FIG.
A thin film laminated structure of a reduction coloring layer 13, an intermediate layer 14, and an oxidation coloring layer 15 is arranged between the layers 6 and 6. this
In ECD, an optical change between a colored state and a decolored state is obtained by a reversible electrochemical reaction. For example, the electrode 12 on the side of the reduced coloring layer 13 has a negative polarity, and the electrode 16 on the side of the oxidized coloring layer 15 has a positive polarity. By applying a voltage of
5 can be brought into a colored state, and by setting the polarities of these voltages to opposite polarities, an optical change can be caused from a colored state to a decolored state.

By the way, in U.S. Patent No. 4,191,453, it is proposed that iridium oxide can be used as an anode material for ECD that develops color through an anode reaction, and in Japanese Patent Application Laid-open No. 56-4679, iridium oxide is proposed to be used as an anode material for ECD, which develops color through an anode reaction. An ECD applied as an oxidation coloring layer in a thin film laminated ECD has been proposed.

However, the iridium oxide oxidation coloring layer used conventionally has drawbacks such as slow response speed and low transmittance, which do not provide sufficient performance in practical terms.

For this reason, as described in US Pat. No. 4,258,984, for example, a wet process is performed in which a thin film of iridium oxide or a thin film of metallic iridium formed by sputtering is anodized in an aqueous sulfuric acid solution by low frequency drive. A method has been proposed to eliminate this drawback, but the transmittance of the iridium oxide thin film formed by this method is at most 70.
% or less, it does not have sufficient transparency, and this method is not suitable because it causes pinholes when producing a thin film laminated structure.

Furthermore, it is still difficult to obtain a highly transparent iridium oxide thin film produced by reactive sputtering, and in order to obtain sufficient EC characteristics (reversible electrochemical reaction characteristics), this iridium oxide thin film must be treated with the aforementioned method. It is necessary to perform anodizing treatment.

In order to solve the above-mentioned problems that occurred when applying an iridium oxide thin film as an oxidized coloring layer of an ECD, the inventors of the present invention have conducted extensive studies, and have found that, in particular, reactive sputtering can be applied to iridium oxide or hydroxide. We discovered that the reaction gas pressure used to form an iridium thin film has a causal relationship with the thin film's transmittance characteristics.

Therefore, the object of the present invention is to use iridium oxide (IrOχ; 0.5 <
χ2, preferably 1<χ2) or a thin film of iridium hydroxide (ir(OH)n;n2) was provided.
The goal is to provide ECD.

That is, the present invention provides an electrochromic device including an oxidation generation layer between a pair of electrodes,
The oxidation generation layer is characterized by being formed of a thin film formed by sputtering iridium in the presence of oxygen and/or water vapor having a gas pressure of 0.1 Torr or more and 1 Torr or less. This makes it possible to provide an ECD having good EC characteristics and an oxidized coloring layer with high transmittance. Moreover, the oxidized color forming layer according to the present invention has an appropriate porous surface state that can cause a sufficiently reversible electrochemical reaction, and can provide an ECD with a fast response speed.

The present invention will be explained below with reference to the drawings.

The ECD of the present invention can use the thin film laminated structure shown in FIG. 1, in which the aforementioned IrOx film or Ir(OH)n film is provided as the oxidized coloring layer 15 in the figure. Further, the reduction coloring layer 13 in the figure can be omitted.

Examples of the reduction color forming layer 13 that can be used in the ECD of the present invention include tungsten dioxide (WO ₂ ), tungsten trioxide (WO ₃ ), molybdenum dioxide (MoO ₂ ), molybdenum trioxide (MoO ₃ ), and vanadium pentoxide ( _The intermediate layer 14 may be made of zircon dioxide (ZrO ₂ ), silicon oxide (SiO ₂ ), silicon dioxide (SiO ₂ ), tantalum pentoxide (Ta ₂ O _{5 )} , or the like. This is an insulating film made of a dielectric material, typically an oxide of or a fluoride such as lithium fluoride (LiF) or magnesium fluoride (MgF ₂ ).

A reversible electrochemically reactive structure consisting of the oxidation coloring layer 15 / intermediate layer 14 / reduction coloring layer 13 is sandwiched between the electrodes 12 and 16, and the electrode 12 is supported by the substrate 11. ing. This base 11
is generally formed of a glass plate, but it is not limited to a glass plate, a plastic plate can also be used, and its position may be provided on the side of the electrode 16, or it may be placed on the side of the electrode 16, depending on the purpose. It may be provided on both sides (for example, for the purpose of serving as a protective cover).
Further, as the electrodes 12 and 16, a transparent conductive film such as indium oxide or tin oxide (ITO) can be used, but if necessary, one of the electrodes 12 and 16 can be made of a suitable metal. It can also be a membrane.

The oxidized coloring layer 15 used in the present invention can be formed by a sputtering apparatus for forming an IrOx or Ir(OH)n thin film as shown in FIG.

The sputtering apparatus shown in FIG.
An object to be evaporated 202 such as a glass plate with an ITO film provided inside it (in the figure, two objects to be evaporated 202a and 202b are placed), a target metal iridium (Ir), and a pallet 203 are placed in their respective predetermined positions. The object 202 to be evaporated is supported by a support 205 which is cooled by a cooling water circulation pipe 204, and the object to be evaporated can be kept at about room temperature during sputtering. Further, the metal iridium pallet 203 is placed on an electrode body 206 (made of stainless steel or the like). Further, instead of this metal iridium pallet 203, other iridium such as iridium oxide or iridium hydroxide may be used. This electrode body 206 is connected to a matching box 208 which is connected to a high frequency power source 207. Further, the vacuum chamber 21 is connected to an oxygen gas cylinder 209 and a vacuum pump 310, respectively, which introduce oxygen gas as a reaction gas.
Valves 311 and 312 are attached to each.

When forming the IrOχ film which becomes the oxidized color forming layer of the present invention, the inside of the vacuum chamber 201 is
After a vacuum state (10 ^-5 Torr) is created by operating the valve 312, the vacuum state is maintained by closing the valve 312.
After that, the valve 311 is opened and oxygen gas is introduced into the vacuum chamber 201 from the oxygen gas cylinder 209, and the gas pressure is 0.1 Torr or more, preferably
Set it to 0.1 Torr to 1 Torr. After that, high frequency power (frequency 13.56MHz: power 1w/cm ² or less, preferably 0.4w/cm ² or less) is applied to the electrode body 206 to generate glow discharge and perform sputtering to form an IrOχ film. Non-evaporated body 202a
and 202b. The IrOx film formed at this time generally has a thickness of 300 Å to 1000 Å, so that it can effectively function as an oxidized coloring layer for ECD.

Figure 3 shows the transmittance of a 350 Å IrOχ film for a helium-neon laser with an oscillation wavelength of 633 nm.
The relationship between oxygen gas pressure and sputtering under high frequency (13.56MHz) power of 0.2w/cm ² is clarified. In other words, the oxygen gas pressure during sputtering is 0.05Torr, 0.1Torr, 0.2Torr and 0.3Torr.
IrOχ of 350Å formed when
When the transmittance of the film was measured using a helium-neon laser, it was found that an IrOχ film with sufficiently high transmittance could be obtained when the oxygen gas pressure was set to 0.1 Torr or higher. Further, the upper limit of the mixed gas pressure should be set to a value that allows uniform glow discharge to occur.

In addition, an Ir(OH)n film can be formed by using water vapor instead of oxygen gas during the sputtering described above, and a mixed gas of oxygen gas and water vapor can also be used. In this case, the same effect as described above can be obtained.

IrOx films obtained by conventional sputtering have poor permeability, and high-quality films cannot be obtained without post-treatment such as anodic oxidation. As is clear from Figure 3, this is the case where the gas is low (approximately
0 ^-3 Torr or less).

Increasing the gas pressure certainly increases the permeability of the membrane, but when used as an oxidation coloring layer in an ECD, an ECD with a fast response speed can be obtained.

Hereinafter, the present invention will be explained according to examples.

Example 1 A 0.8 mm glass substrate provided with an ITO film and metal iridium were prepared, and each was attached to a sputtering apparatus shown in FIG. 2. Thereafter, the air in the vacuum chamber of the sputtering apparatus was evacuated by a vacuum pump, and oxygen gas was introduced into the vacuum chamber from an oxygen gas introduction tube to obtain an oxidizing gas pressure of 0.2 Torr. Next, a high frequency of 13.56 MHz was applied to the electrode body under a power of 0.2 W/cm ² and sputtering was performed for about 1 hour to form an IrOχ film of 350 Å on the ITO film.

On top of this film, a Ta ₂ O ₅ film is deposited by vacuum evaporation method.
The degree of vacuum at this time was 2.1× with a film thickness of 3000 Å.
The deposition rate was 10 ^-5 Torr and 8 Å/sec. Further, on this film, a WO ₃ film serving as a reduction coloring layer was provided with a thickness of 4000 Å using a vacuum evaporation method, and a semi-transparent Au film was further provided with a thickness of 300 Å.

The ECD created in this way had higher transparency than conventional ones. Furthermore, this
A DC voltage of 2.2 V was applied between the ECD electrodes (ITO film and semi-transparent Au film) (the ITO film electrode was set to positive polarity, and the semi-transparent Au film was
When a negative polarity of the membrane electrode was applied, the color changed to a colored state with an extremely fast response speed. Then,
When the voltage supply was stopped, this coloring state was maintained, and furthermore, with the opposite polarity to the above-mentioned polarity, the coloring state was maintained.
When a DC voltage of 2.2V was applied, an optical change occurred from a colored state to a decolored state.

Example 2 An ECD was prepared in the same manner as in Example 1 except that water vapor was used instead of the oxygen gas used in Example 1, and when it was further evaluated, it was found to be similar to that in Example 1. The results were obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an electrochromic device. FIG. 2 is a cross-sectional view schematically showing the sputtering device used in the present invention. FIG. 3 is an explanatory diagram showing the relationship between gas pressure and transmittance of an IrOx film. 11; Substrate, 12, 16; Electrode, 13; Reduction coloring layer, 14; Intermediate layer, 15; Oxidation coloring layer, 20
1; Vacuum chamber, 202; Evaporation target, 203; Metal iridium pallet, 204; Cooling water circulation pipe,
205; Support, 206; Electrode, 207; High frequency power supply, 208; Matching box, 209; Oxygen gas cylinder, 310; Vacuum pump, 311,3
12; Valve.

Claims (1)

[Claims] 1. In an electrochromic device having an oxidation generation layer between a pair of electrodes, the oxidation generation layer is
An electrochromic device comprising a thin film formed by sputtering iridium in the presence of oxygen and/or water vapor having a gas pressure of 0.1 Torr or more and 1 Torr or less.