JPH0443252B2 - - 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 specifically to an ECD using an oxygen coloring layer with improved transparency. .

ECDs can be applied to, for example, numeric display elements, X-Y matrix display elements, optical shutters, diaphragms, etc. For example, an ECD with an all-solid thin film laminated structure shown in FIG. 1 is known. That is, in the ECD shown in FIG. 1, a thin film laminated structure of a reduction coloring layer 13, an intermediate layer 14, and an oxidation coloring layer 15 is arranged between a pair of electrodes 12 and 16. 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, U.S. Pat. No. 4,191,453 proposes that iridium oxide be used as an anode material for ECD that develops color through an anode reaction, and JP-A-56-4679 proposes that iridium oxide be used as an all-solid material as described above. An ECD applied as an oxidation coloring layer in a thin film laminated ECD has been proposed.

However, the iridium oxide oxide coloring layer used in the past has disadvantages in that it does not have sufficient practical performance, such as slow response speed and low transmittance.

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.
%, 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 present inventors conducted extensive studies and found that, in particular, by reactive sputtering, iridium oxide or hydroxide By using a mixed gas containing oxygen gas and hydrogen gas as a reaction gas when forming an iridium thin film, and in some cases, a mixed gas containing water vapor as well, the anodic oxidation treatment (wet Good EC characteristics can be obtained with a completely dry process without using a dry process.
Moreover, it has been found that a thin film of iridium oxide or iridium hydroxide can be obtained with high transparency.

Therefore, the object of the present invention is to use iridium oxide (IrOx; 0.5<x<2, preferably 1<x2) or iridium hydroxide (IrOx) as an oxidized coloring layer.
An object of the present invention is to provide an ECD having an electrochemically reactive laminated structure in which a thin film of (OH)n;n2) is formed by a dry process and in which pinholes are not generated.

Another object of the present invention is to also have high transmittance characteristics.
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 generating layer is characterized by being formed of a thin film formed by sputtering indium in the presence of a mixed gas containing hydrogen gas and at least one of oxidizing gas and water vapor.

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 coloring layer 13 that can be used in the ECD of the present invention include tungsten dioxide (WO ₂ ), tungsten trioxide (WO ₃ ), molybdenum dioxide (M ₀ O ₂ ), molybdenum trioxide (M 0 O 3 ), and molybdenum trioxide (M ₀ O ₃ ). A thin film such as vanadium oxide (V ₂ O ₅ ) can be used. The intermediate layer 14 is made of zircon dioxide (Z _r
O ₂ ), silicon oxide (SiO), silicon dioxide (SiO ₂ )
It is an insulating film made of a dielectric material, typically an oxide such as tantalum pentoxide (Ta ₂ O ₅ ) or a fluoride such as lithium fluoride (LiF) or magnesium fluoride (MgF ₂ ).

A reversibly electrochemically reactive structure composed 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 base 11. There is. 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 also be provided on the side of the electrode 16, depending on the purpose ( For example, it may be provided on both sides (for purposes such as serving as a protective cover). or,
As the electrodes 12 and 16, a transparent conductive film such as indium oxide, tin oxide or ITO (Indinm Tin Oxide) can be used.
and 16 may be made of a suitable metal film.

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

The sputtering apparatus shown in FIG.
An object to be evaporated 202 (two objects to be evaporated 202a and 202b are arranged in the figure), such as a glass plate provided with an ITO film, and a target metal iridium (Ir) pallet 203 are placed at predetermined positions. , the object to be deposited 202 is the cooling water circulation pipe 2
The substrate is supported by a support 205 which is cooled by a heating element 04, and the object to be deposited can be kept at about room temperature during sputtering. Further, the metal iridium pallet 203 is arranged on an electrode body 206 made of stainless steel or the like. Further, in place 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 connected to a high frequency power source 207.
is connected to. Further, the vacuum chamber 21 includes an oxygen gas cylinder 209 that introduces oxygen gas as a reaction gas, and a hydrogen gas cylinder 31 that introduces hydrogen gas.
3 and a vacuum pump 310, and valves 311, 314, and 312 are attached to each.

When forming the IrOx film that becomes the oxidized coloring 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 valves 311 and 314 are opened and oxygen gas and hydrogen gas are introduced into the vacuum chamber 201 from the oxygen gas cylinder 209 and the hydrogen gas cylinder 313, and the gas pressure is 0.1 Torr or more, preferably.
Set it to 0.1Torr to 1Torr. 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 claw discharge and perform sputtering to form an IrOx film. Deposited 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.

The mixed gas used at this time is the volume ratio of hydrogen gas and oxygen gas, that is, V _H2 (hydrogen gas volume) / V _O2
(Oxygen gas volume) is 0.1 to 1.5, preferably 0.5 to 1.5
Valid when 1.5.

Figure 3A shows the transmittance of a 350 Å IrOx film for a helium-neon laser with an oscillation wavelength of 633 nm.
High frequency (13.56MHz) power of 0.4W/ ^cm2 and
The relationship between the mixing ratio of oxygen gas and hydrogen gas under a gas pressure of 0.1 Torr is clarified. In other words, the mixing ratio of the mixed gas during sputtering (V _H2 /V _O2 )
The transmittance of the 350 Å IrOx film formed when the
When measured using a neon laser, Figure 3A
A curve 31 with good transmittance characteristics shown in was obtained.

Further, FIG. 3B shows the relationship between the hole mobility (μH) and the mixing ratio of the mixed gas. This Hall mobility measurement was performed by Van der Pauw (Van der Pauw).
Pauw) law. The Van der Pauw method is based on L.
It is detailed in "Philips Research Report (Philips, Res. Rept), 13 (1958) 1" by J. Van der Pauw, and an overview thereof will be explained below. In other words, the Van der Pauw method uses the rectangular shape shown in Figure 4A.
The four ends of the IrOx film are 41, 42, 43, and 4, respectively.
4, the needle electrode is brought into contact with the electrodes 41-42.
When a current I is passed between them, a voltage V _43-44 is generated between the electrodes 43-44, and the formula (1); R _{(41-42, 43-44)} = V _43-44 /
If I holds true and formula (1) is defined, the sheet resistance is ρ _S = π/ln2, R _{(41-42, 43-44)} + R _{(41-44, 41-42)} /2
・f (x) Here, x=min(R _{(41-42, 43-44)} /R _{(41-44, 43-42)} , R _{(41-44
, 43-42)} /R _{(41-42, 43-44)} ).

Further, if a magnetic field B is applied to the rectangle shown in FIG. 4 in a direction perpendicular to the paper surface, the Hall coefficient can be determined as Rs=ΔR _{(41-43, 42-44)} /B. Here, ΔR _{(41-43, 42-44)} is R _{(41-43,
42-44)} due to magnetic field B. Here, f
(x) is a function defined by 0<x≦1, and is a solution of the following transcendental equation.

ln2/f=ln{2cosh(1-x/1+x·ln2/f)} From ρs and Rs, the Hall mobility of the carrier can be found from _μH =Rs/ρs.

Therefore, the Hall mobility (μ _H ) corresponds to the four ends 41, 42, 43, and 44, as shown in Figure 4B.
It can be obtained by bringing a needle electrode into contact with the IrOx film and obtaining the measured value. In the figure, 45 is a switching box.

As can be seen from Figure 3B, the Hall mobility (μ _H ) is
20 to 60 in all cases as shown by curve 32
It was about cm ² /v·sec, which was good. or,
Since the sign of the Hall coefficient is positive, this film can also be applied as a P-type transparent conductive film.

Further, in a preferred embodiment of the present invention, the gas pressure of the mixed gas containing oxygen gas and hydrogen gas during sputtering is set to 0.1 Torr or more, preferably 0.1 to 1 Torr, thereby forming an IrOx film or an IrOx film with high transmittance.
(OH)n film can be obtained. Further, the upper limit of the mixed gas pressure should be set to a value that allows uniform glow discharge to occur.

Furthermore, the 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, hydrogen gas, and water vapor can also be used. In this case, the same effect as described above can be obtained.

In addition, in addition to the sputtering device used previously when forming the oxidized color forming layer of the present invention, a reactive high frequency ion plating method or a reactive arc discharge ion plating method can be used, and in this case, the same method as described above can be used. The effect of this can be obtained.

The IrOx film obtained by conventional sputtering has poor permeability and requires post-treatment such as anodization, and the film formed by this method also has pinholes, which is not desirable. According to the invention, by using sputtering using a mixed gas containing hydrogen gas as a reaction gas, it has high-speed response and high transmittance.
You can get ECD.

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 hydrogen gas and oxygen gas were introduced into the vacuum chamber through the hydrogen gas and oxygen gas introduction pipes to obtain a mixed gas pressure of 0.1 Torr. Next, a high frequency of 13.56 MHz was applied to the electrode body under a power of 0.4 W/cm ² .
Perform sputtering to deposit 350Å of IrOx on the ITO film.
A film was formed. At this time, the ratio of mixed gas (V _H2 /
V _O2 ) was varied as 0, 0.5, 1.0, 1.5 and 2.0.

For each of the five samples created in this way, Ta ₂ O ₅ was deposited on the IrOx film by vacuum evaporation.
The film was provided with a thickness of 3000 Å. The degree of vacuum at this time is
The deposition rate was 2.1×10 ⁻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 by vacuum evaporation, and a semi-transparent Au film was further provided with a thickness of 300 Å.

When the characteristics (color development/discoloration characteristics) of the five types of ECDs prepared in this way were measured, the results shown in the plots in FIGS. 5A and 5B were obtained. Fifth
Figure A shows the change in transmittance (%) during decolorization with respect to the mixing ratio of the mixed gas.

Figure 5B shows the distance between the ECD electrodes (IOT film and semi-transparent Au film), with the transmittance (%) at the time of decolorization set as 100.
It represents the rate of change (%) in transmittance (%) when a DC voltage of 2.2 V (ITO membrane electrode was made positive and the translucent Au membrane electrode was made negative polarity) was applied for 0.2 seconds.

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 sectional view schematically showing the sputtering device used in the present invention. Figure 3A
2 is an explanatory diagram showing the relationship between the mixing ratio of mixed gas and the transmittance of an IrOx film. FIG. FIG. 3B is an explanatory diagram showing the relationship between the mixing ratio of the mixed gas and the hole mobility of the IrOx film. FIG. 4A is a plan view showing a rectangular IrOx film used in measuring hole mobility. 4B is an explanatory diagram of an apparatus showing a method for measuring Hall mobility. FIG. 5A is an explanatory diagram showing the relationship between the transmittance of the ECD during decolorization and the mixing ratio of the mixed gas. FIG. 5B is an explanatory diagram showing the relationship between the rate of change in transmittance and the mixing ratio of the mixed gas when the ECD is energized for 0.2 seconds, assuming that the transmittance during decolorization is 100. 11; Substrate, 12, 16; Electrode, 13; Reduction coloring layer, 14; Intermediate layer, 15; Oxidation coloring layer, 20
1; Vacuum chamber, 202; Deposited object, 203; Metal iridium pallet, 204; Cooling water circulation pipe,
205; Support, 206; Electrode, 207; High frequency power source, 208; Matching box, 209; Oxygen gas cylinder, 310; Vacuum pump, 313; Hydrogen gas cylinder, 311, 312, 314; Valve.

Claims (1)

[Claims] 1. In an electrochromic device having an oxidation generation layer between a pair of electrodes, the oxidation generation layer is formed in the presence of a mixed gas containing hydrogen gas and at least one of an oxidation gas and water vapor. An electrochromic element characterized by being constructed from a thin film formed by sputtering indium. 2. The electrochromic device according to claim 1, wherein the iridium is metallic iridium. 3. The electrochromic device according to claim 1, wherein the mixed gas has a gas pressure of 0.1 Torr or more and 1 Torr or less. 4. The electrochromic device according to claim 1, wherein the mixed gas contains hydrogen gas at a ratio of 0.1 to 1.5 volumes per 1 volume of oxygen gas. 5. The electrochromic device according to claim 1, wherein the mixed gas contains hydrogen gas at a ratio of 0.5 to 1.5 volumes per 1 volume of oxygen gas.