JPS60247227A - Transmission type electrochromic display device - Google Patents

Abstract

PURPOSE:To enable long-period use at high temp. by forming a transparent electrode consisting of a specified metal, oxide or hydroxide thereof as dispersed matter and a transparent, solid and electrically conductive dispersion medium by a vacuum thin film forming technique or a thick film method. CONSTITUTION:An electrochromic (EC) display device is composed essentially of the transparent display electrode A, the EC layer B which develops color by reduction and a counter electrode D. A transparent ionic conductive layer C may be held between the layer B and the electrode D. At this time, a transparent dispersion electrode D1 consisting of one or more kinds of metals selected among Ru, Os, Rh, Pt, Pd and Ni, oxides or hydroxides thereof as dispersed matter D11 and a transparent, solid and electrically conductive dispersion medium D12 is used as the counter electrode D. The electrode D1 is formed by a vacuum thin film forming technique or a thick film method. At least one among the layers B, C and the electrode D1 contains cations necessary for the development of color in the layer B or a cation feeding source which releases said cations under applied voltage. The resulting ECD is colorless and transparent and undergoes little reduction in contrast even after long-period use at high temp.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical field of the invention) The present invention is a novel transmission electrochromic (hereinafter referred to as "
EC) display device.

(Background of the Invention) E is colored by applying a voltage similar to that of a dry cell battery, and fades to its original colorless and transparent state by applying a reverse voltage.
BACKGROUND ART C display devices (hereinafter abbreviated as ECD) are being actively researched for practical use as a means of displaying numbers and other items using Japanese-shaped seven segments. One of them is ECD using a reducing color-forming EC substance such as -OB or Mo(%).

In order for these EC substances to develop color, simultaneous injection of electrons (e-) and cations (X+) is required, and the reaction formula involved in color development and decolorization is believed to be as follows.

When decoloring: WO3+ne +nX ↓↑ ↓↑ When developing color: XnWO3 And, as the cation (X”), H, which has a small ionic radius and is easy to move, is mainly used. These cations do not always need to be cations. Water is used as a cation source, especially in the case of H+, since cations only need to be generated when a voltage is applied and an electric field is formed.Water decomposes in the electric field according to H20 → H+01 (- .It seems that a very small amount of water is sufficient.
The amount of water that is naturally drawn into the WO3 layer from the atmosphere often suffices.

However, even if the WO3 layer is simply sandwiched between a pair of electrodes and a voltage is applied to develop color, the color cannot be easily erased. This is because even if a reverse voltage is applied to erase the color, electrons (e~) will flow in from the electrode side connected to the cathode, so if there is H'', WO3 + ne + nll
→ This is because the reaction of 1lnWo3 occurs and the coloring occurs.

Therefore, between the WO layer and one electrode, an insulating layer such as 5i02. An ECD equipped with MgF was proposed (Special Publication No. 46098/1983). The insulating layer of this ECD does not allow the movement of electrons, but allows the movement of OH- ions, and these OH'''' ions carry electricity, and 20H-H2O+ (1/2) is generated between the insulating layer and the electrode. It seems that electrons are released to the anode side according to the reaction 02↑+2e-.

In other words, when developing color, (cathode side) WO3+ne +nH-=tlnWO3(
Anode side) n(OH-) → nH2O+ (n/2) 021 +2ne- reaction is estimated, and at the time of decolorization, (anode side) Hnl'103 →WO, +ne-+nH
It is estimated that the following reaction occurs: "(Cathode side) n1120+2ne-→nOH"-+ (n/2) H2↑.

It is clear from these formulas that in reality
No. -46098 has the disadvantage that water is consumed by driving, so if water is not quickly supplied from the atmosphere, the color will not develop, and 02 gas and ■2 gas are released during driving, which causes delamination. there were.

Therefore, an all-solid-state ECD was proposed in which an "electronic insulating layer that is a good ion conductor/oxidation color-forming EC layer" was provided next to the WO3 layer (Japanese Patent Laid-Open No. 56-4679). This uses iridium hydroxide or nickel hydroxide as the oxidative color-forming EC layer, and when coloring in 3, Ir (On) m + n (OH'''') (colorless and transparent) ↓ Tr (Oll) 1 on the anode side. -pH□0+qH20+ r (
e-), and when -03 is decolored, Ir (Oll) 12- pi2o+ql12o+ is formed on the cathode side.
It is thought that it reacts with r (e-)↓ Tr (0 old 11 + n (OH''''). Therefore, water is regenerated, so no water is consumed, and no 112 gas or 02 gas is generated. .

However, when using an iridium hydroxide or nickel hydroxide layer, when subjected to long-term high temperature durability tests,
It was found that the color remained even when the color was erased, and the color did not become the original colorless and transparent, resulting in a decrease in the contrast between development and erasure.

(Object of the Invention) Therefore, the object of the present invention is to improve the drawback when using an iridium hydroxide or nickel hydroxide layer, namely, the decrease in contrast when subjected to a long-term high temperature durability test. .

(Summary of the Invention) As a result of intensive research, the present inventors discovered that 'Ru,
It consists of a dispersoid consisting of one or more metals selected from Os, Rb+Pt+Pd, and Ni or their oxides or hydroxides, and a transparent solid conductive dispersion medium, and is formed using a vacuum thin film forming technique or a thick film method. Formed transparent electrode
It has been discovered that the above-mentioned drawbacks of the iridium hydroxide layer can be overcome by using the iridium hydroxide layer, and the present invention has been completed.

Therefore, the present invention provides an electrochromic display device comprising a transparent display electrode (A), a reductive color-forming electrochromic layer (B), a transparent ion conductive layer (C) if necessary, and a counter electrode (D). The counter electrode (D) is a dispersoid (D11) consisting of one or more metals themselves or their oxides or hydroxides selected from Ru, Os, Rh, Pt, Pd, and the like. and a transparent solid conductive dispersion medium (D12), using a transparent dispersion electrode (Dl) formed by a vacuum thin film formation technique or a thick film method, and using the above (B), (C) and (DI). Provided is an ECD characterized in that at least one layer of (B) contains cations necessary for color development or a cation source that releases cations upon application of voltage.

As the transparent display electrode (A) used in the present invention, for example, 5n02. In2O3, TTO(In, O,
mixed with about 5% of 5n02). The thickness of the electrode (A) is generally 0.01 to 0.5 μm, although it depends on the transparency and resistance. Therefore,
The electrode (A) is generally made by a vacuum thin film forming technique such as vacuum evaporation, reactive evaporation, ion blating, reactive ion blating, or sputtering, but in some cases, it may be made using an organometallic compound such as a metal alcoholade or its oligomer. It may be made by a so-called thick film method in which a solution is applied and baked to form a film.

As already known, amorphous-03 or MooB is used for the reduction color-forming EC layer (B). These EC layers are generally formed to a thickness of 0.01 to several μm by vacuum thin film formation technology.

The transparent ion conductive layer (C) is provided as necessary in order to give the 0ECD of the present invention a memory property, that is, a property that the coloring state is maintained even after the voltage application is stopped after coloring. Examples of materials include:

■Tantalum oxide (Taz%), niobium oxide (Nb, 05), zirconium oxide (Zr0) containing a small amount of water
2) Titanium oxide (Ti02), hafnium oxide (Il)
fO2), yttrium oxide (Y, O,), lanthanum oxide (La203), silicon oxide (S102>), magnesium fluoride, zirconium phosphate, or a mixture thereof (these substances are insulators for electrons) are protons (H+) and hydroxy ions (Oll-)
It is a good conductor. ); ■Sodium chloride Potassium chloride, sodium bromide, potassium bromide, Na5Zr2S+2P0,2, Na14.
(Zrstxp3-XO,,, Na s Y S +
+ Solid electrolyte such as 012, llbAg, I, etc.; ■ Water or a synthetic resin containing a proton source, such as β-hydroxyethyl methacrylate and 2-acrylamide-2-
Copolymers with methylpropanesulfonic acid, hydrated vinyl polymers such as hydrated methyl methacrylate copolymers, hydrated polyesters, etc.; Electrolytes such as sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, butyric acid, oxalic acid, etc. acid or its aqueous solution,
Aqueous solutions of alkalis such as sodium hydroxide, 'potassium hydroxide, aqueous solutions of solid strong electrolytes such as sodium chloride, lithium chloride, potassium chloride, and lithium sulfate; ■ Semi-solid gel electrolytes, such as electrolyte aqueous solutions with gelling agents such as polyvinyl Examples include gels made with alcohol, CMC, agar, gelatin, etc.

Therefore, the transparent ion conductive layer (C) is formed by vacuum thin film forming technology, thick film method, encapsulation, injection, coating, or other means. (C) The thickness of the layer is o, ooi μm- depending on the material.
It varies up to IN rank.

In the present invention, a transparent dispersion electrode (Dl) consisting of a dispersoid (Dll) and a transparent solid conductive dispersion medium (DI2) is used as the counter electrode. First, the dispersoid (Dll) will be explained.

Dispersoid (D 11) is Ru, Os, Rh, Pt, Pd
and Ni or their oxides or hydroxides, of which oxides or hydroxides are preferred.

As the dispersion medium (D12), for example, SnO2+ In
Transparent solid conductive compounds such as 2O3°ITO and ZnO are used.

A method of manufacturing such a transparent dispersion electrode (Dl) will be explained as follows. In the following explanation, is the dispersoid (D 11
), Mlo means its oxide, Ml means a metal element constituting the dispersion medium (Dl2), M,
0 means its oxide.

(i) Vacuum deposition by resistance heating, electron beam heating, radio frequency heating or laser beam heating: (ia) In the case of non-reactivity, ◎M, , MIO 0Ml0° is used as the evaporation source material.

(ib) In the case of reactivity, in the presence of 02 gas and with an activation means (for example, high frequency application or heating), as an evaporation source material ◎M,, Mlo 0M2. Use M20.

(ii) High frequency sputtering: (ii-a) In the case of non-reactivity, in the presence of an inert gas, 1 ◎M, , M, 0 0Ml0 is used as a multi-element or composite target.

(ii-b) In the presence of reactive 02 gas (inert gas may be added), 0M1. M, 0 0M2. Use M20.

(iii) Direct current sputtering: 0M1 0M2 is used as a multi-element or composite target in the presence of 0□ gas (an inert gas may be added).

(iv) In addition, after forming a mixed metal thin film of Ml and Ml by any of the methods (i), (ii), and (iii) above, it is oxidized by heating, for example, to 250 to 300 ''c. Then, the layer is changed to a dispersed layer (Dl) of Ml and M2O or a dispersed layer (DI) of Mlo and M2O.Ml that can be used in this method include Sn, In,
Examples include.

As mentioned above, Mlo means an oxide, but if water is present near Mlo, it can be understood that Mlo ・H,0 can also be written as Ml (OH)2, so it becomes an oxide. It can also be treated as a hydroxide. Therefore, the metal oxide and hydroxide constituting the dispersoid (Dll) are not strictly distinguished.

In any case, the dispersoid (Dll) must be dispersed in the transparent dispersion medium (D12) in the form of extremely fine particles, and for this purpose, the above-mentioned vacuum thin film formation technology is used to manufacture the dispersion layer (DI). It is preferable. Further, the dispersion layer (DI) may be formed by a thick film method in which a mixed solution of an organic metal compound such as a metal alcoholade or an oligomer thereof is applied and baked to form a film.

This results in a transparent dispersion electrode (Dl).

The thickness of the transparent dispersion layer (Dl) is generally 0°005
A thickness of about 11 μm to 11 μm is sufficient.

As mentioned above, cations are necessary for the color development of the reduction color-forming EC layer (B), and at least one of the layers (B), (C), and (Dl) has cations or voltage applied. It is necessary to include a cation source that releases cations due to Above, limited to water (H2O). In the case of water, water often naturally enters the layer from the atmosphere even if it is not specifically included during the production of ECD.

In this way, the 0ECD of the present invention is constructed. ECD of the present invention
generally consists of three or four layers: a display electrode (A), an EC layer (B), in some cases an ion conductive layer (C), and a dispersion electrode (Di).
Although it has a layered structure, it may also have a structure as shown in FIGS. 2A and 2B.

In the figure, (E) is an auxiliary electrode.

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 this coloring state remains unchanged even when the voltage application is stopped when the (C) layer is present. If it is held for a long time and a similar reverse voltage 4 is applied, it returns to its original colorless and transparent state in a slightly shorter time than the time required for color development. Although it takes time, the electrodes (A) and (Dl)
Even if it is short-circuited, the color will disappear.

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 Sr+ and metal Rh Vacuum degree: 5 XIO
Torr 02 partial pressure: 3
) A transparent dispersion electrode (Dl) with a film thickness of 700 people was formed. This dispersion electrode (Dl) had a dispersoid (Dll) ratio of 20% by weight and a sheet resistance of 500Ω/hole.

Next, a transparent ion conductive layer with a thickness of 5,000 yen is deposited on top of it by vacuum evaporation under the following conditions: Evaporation source: Ta 2% Degree of vacuum: 5X10-≦Torr 5 4 0□ Partial pressure: 4 XIO Torr Substrate temperature: 150°C (C) was formed.

In addition, the following conditions: Evaporation source: WO2 Degree of vacuum: 5 XIO Torr Ar partial pressure: 4 xlo-” Torr Substrate temperature: 15
A transparent amorphous 03 layer (B) with a thickness of 5000 was formed by vacuum deposition at 0°C.

Finally, the following conditions: Evaporation source: In
Mixture of 20B and 5n02 Degree of vacuum: 5 xio
Torr Partial pressure: 3 xio-' Torr Substrate temperature: 150°C by high frequency ion blating to reduce the film thickness to 250°C.
0 transparent display electrodes (A) were 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 was applied through the electrodes (A) and (DI), it developed a blue color at 400 m5ec.
Transmittance (Tc) during color development is 20% at wavelength λ-600nm
This coloring state was maintained even after the voltage application was stopped. Next, when applying a decoloring voltage of -1.4 volts, 350
m5ec returns to the original colorless transparency, and the transmittance at decolorization (T
b) was 80%.

(Example 2) The glass substrate (S) used in Example 1 was prepared, and the following conditions were placed on it: Evaporation source: A mixed sintered body of In2O3 and SnO□ (IT
Mixture target of O) and metal Rh Vacuum degree: 5 xlOTorr Ar partial pressure: ' 5 A transparent dispersion electrode (with a film thickness of about 500 mm) using Dl2 as a dispersion medium (Dl2)
Di) was formed. This transparent dispersion electrode (DI) had a dispersoid (D11) ratio of 25% and a sheet resistance of 180Ω/hole.

Hereinafter, as in Example 1, transparent ion conductive layers (C>,
wo, form layer (B) and display electrode (A), and ECD
It was created.

After sealing with epoxy resin, a color development and fading test was performed and the result was +1.
250 m5ec at 4v, Tc=25%,
200 m5ec at -1,4V, Tb=75% (λ
-600 nm).

(Comparative Example 1) A glass substrate (S) on which an ITO counter electrode (D) with a thickness of 0.15 μm was formed was prepared, and the following conditions were applied on the electrode (D): Evaporation source: metal Ir Vacuum degree: 5 A transparent EC layer having a thickness of 700 mm and consisting only of iridium oxide was formed by high-frequency ion blasting under Xl0-' Torr -102 partial pressure: 3 XIO Torr substrate temperature: 20°C.

Thereafter, in the same manner as in Example 1, layers (C), (B), and 8 (A>) were laminated to form an ECD and sealed. The resulting ECD was colored slightly brown even before the coloring voltage was applied. and an Ooj of ±1.54 Roux in the atmosphere.

Even after applying the 511z AC voltage for 500 minutes, it did not become completely colorless and transparent. After decoloring, a color development/decolorization test was performed, and it was found that Tc = 15%, 1 at 150 m5ec.
Tb = 50% at 00 m5ec.

(High-temperature durability test) The sealed ECDs prepared in Example 1.2 and Comparative Example 1 were subjected to a high-temperature durability test at 80° C. for 200 hours after the contrast ratio was determined, and then the contrast ratio was determined. The results are shown in Table 1 below. The contrast ratio was determined as follows.

Contrast ratio - 1 og (TI/T2) T1 - Saturated transmittance when decoloring (%) T2 - Saturated transmittance when coloring (%) Measurement wavelength λ - 600 nm Table 1 (High temperature durability test data) (Invention Effects) As described above, according to the present invention, a colorless and transparent ECD with no coloration after production can be obtained, and an ECD with extremely little decrease in contrast after a high-temperature durability test can be obtained. Also, since the conventional iridium hydroxide or nickel hydroxide layer is not required, the overall structure of the ECD is simplified.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an ECD according to Example 1 of the present invention. 2A and 2B are cross-sectional views of an ECD according to another embodiment of the present invention. [Explanation of symbols of main parts] A...Transparent display electrode B...Reduction color forming EC layer C...Transparent ion conductive layer Dl...Transparent dispersion electrode (counter electrode) E...Auxiliary electrode S ...Substrate applicant: Nippon Kogaku Co., Ltd. Agent Takao Watanabe 1 0

Claims (1)

[Claims] In an electrochromic display device comprising a transparent display electrode (A), a reductive color-forming electrochromic layer (B), a transparent ion conductive layer (C) and a counter electrode (D) as required, As the counter electrode (D), Ru, Os, Rh,
A dispersoid (Dll) consisting of one or more metals selected from Pt, Pd and Ni or their oxides or hydroxides and a transparent solid conductive dispersion medium (DI2).
), using a transparent dispersion electrode (Dl) formed by vacuum thin film formation technology or thick film method, and (B), (
A transmission type electrochromic display device, characterized in that at least one layer of (C) and (Dl) contains cations necessary for color development in (B) or a cation supply source that releases cations upon application of voltage.