JPH07159815A - Electrochromic element - Google Patents

Abstract

PURPOSE:To obtain an electrochromic element with decreased blurring of colors in which deterioration of structural films of the element is prevented. CONSTITUTION:This electrochromic element consists of at least a first electrode layer 2, reversible electrolytic oxidized layer or oxidation color developing type electrochromic layer 3, ionic conductive layer 4, reduction color developing electrochromic layer 5 and second electrode layer 6, successively formed on a substrate. In this element, an insulating layer 7 against electrons and ions is selectively formed between the first electrode layer 2 and the reversible electrolytic oxidizing layer or oxidation color developing type electrochromic layer 3 or between the reversible electrolytic oxiditzing layer or oxidation color developing type electrochromic layer 3 and the ionic conductive layer 4.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrochromic device.

[0002]

2. Description of the Related Art Electrochromic devices (hereinafter referred to as "E
"C element") is a light quantity control element utilizing reversible optical density change accompanied by electrochemical change, and has a characteristic that the light transmittance can be arbitrarily adjusted by applying a voltage from the outside. .

Regarding the constitution of the EC element, there are various types such as a solution type, a gel type and an all solid type as the form of the material (mainly the electrolyte). However, due to the process, the EC color fading layer, the electrolyte layer, the electrode The all-solid-state thin film type in which all (two electrode layers) and the like are continuously formed into a thin film has an advantage that steps such as bonding and liquid material sealing are not required.

In a transmissive EC element, both electrode layers are transparent, and in general, a transparent conductive film forming an electrode is formed on a transparent substrate such as glass by vacuum deposition or sputtering. Therefore, ITO is the most widely used at present. Incidentally, ZnO, SnO _{2 and} other materials are also being studied. In addition, in the reflective EC element,
A metal film such as an Al film may be used as one of the electrodes.

When the EC element is used as a display element, patterning (selective arrangement) of the display portion is required.
For example, in the display element of the camera finder developed by the present inventors, the EC color-decoloring layer is patterned by the photolithography (lift-off) method to pattern the display portion. That is, first, the ITO (first
Electrode) layer is formed.

Then, a photoresist is applied on the ITO, exposed and developed to form a pattern in which the photoresist is removed at a portion where a reversible electrolytic oxidation layer or an oxidation coloring type electrochromic layer described later is to be left. To do. The photoresist pattern is formed by a so-called lift-off method.

After that, a reversible electrolytic oxidation layer or an oxidative coloring type electrochromic layer is vapor-deposited on the ITO and the patterned photoresist, and then the photoresist is removed by a solvent or the like to form a desired display portion. Only the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer constituting the layer is left on the ITO.

Then, an ion conductive layer and a reduction coloring electrochromic layer are laminated on the ITO and the reversible electrolytic oxidation layer or the oxidation coloring EC layer, and further ITO (second electrode layer) is laminated. , EC elements are formed.

In the EC device formed as described above, by applying a voltage between the first and second electrodes, the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer, the ion conductive layer and the reduction layer are formed. An electrochemical reaction occurs in the color forming electrochromic layer to cause coloration. When a voltage is applied in the opposite direction, a reaction opposite to the above reaction occurs and the EC element is decolored.

The reversible electrolytic oxidation layer or the oxidative coloring type electrochromic layer is composed of a layer of iridium oxide or a mixture of iridium hydroxide and tin oxide (hereinafter referred to as iridium oxide etc.) and has a color tone at the time of color development. Is grayish white. The ion conductive layer is made of tantalum oxide which is a solid electrolyte. The reduction coloring electrochromic layer is made of tungsten oxide and changes from colorless to blue due to a coloring reaction.

In the above EC element, the iridium oxide layer (reversible electrolytic oxidation layer or oxidative coloring electrochromic layer) is patterned to form the EC element, but the tungsten oxide layer ( An EC element may be formed by patterning a reduction coloring type electrochromic layer). However, since the iridium oxide layer is more durable than the tungsten oxide layer, the iridium oxide layer is generally patterned to form an EC element.

[0012] The performance of the EC device is particularly determined by the moisture content in the film in the so-called EC3 layer of the two EC layers and the solid electrolyte layer.
It is greatly affected by factors such as the interface state and minute spots, and these factors are largely dependent on the film forming conditions of the EC element and the stacking conditions (whether or not an atmospheric state is created between the stacks). Therefore, it is considered desirable to continuously stack the EC3 layers in a vacuum state in consideration of the influence on the EC device performance, particularly durability.

[0013]

However, in the above-mentioned conventional EC element, a photolithography process for patterning a layer of iridium oxide or the like must be performed, in which case a developing solution (usually weak alkaline in a positive resist) or Since it is exposed to the etching liquid, there has been a problem that the constituent films, particularly the EC3 layer, are significantly deteriorated. In particular, the deterioration of durability against the color-erasing / erasing drive is most remarkable, and has been confirmed by various experiments. Further, since the EC layer is exposed to the atmospheric state during patterning, continuous film formation (stacking) of the EC3 layer in a vacuum cannot be performed.

In addition, dry etching without using an etching solution, a lift-off method in which patterning is performed using a resist as a mask, and the like, eventually one of the two layers of the coloring / discoloring layer (for example, an iridium oxide layer and a tungsten oxide layer) is patterned. Therefore, there is a problem in that the constituent film of the EC element is deteriorated by being exposed to a resist stripping solution or the like, and in particular, the tungsten oxide layer is greatly deteriorated.

In addition, in the above-described conventional patterning (lift-off method), the resist remains due to the solidification of the resist due to the radiant heat during the formation of the iridium oxide layer, or the leak current often occurs due to the patterning edge. There was a major obstacle to improving the yield.

Further, in the conventional EC element, since the iridium oxide layer is patterned out of the two layers of the coloring / decoloring EC layer (iridium oxide layer and tungsten oxide layer), the electric field also spreads in the film surface direction. However, there is a problem in that the tungsten oxide layer, which is the facing erasing / erasing layer, is colored up to a portion without the iridium oxide or the like layer, in other words, the color is bleed into the portion without the iridium oxide or the like layer. In particular, this is a problem when the pattern is fine.

It is possible to reduce color bleeding by patterning the tungsten oxide layer, which is markedly colored, but as described in the conventional example, the tungsten oxide is more durable than iridium oxide or the like. Since it is weak, it is difficult to form a highly durable EC element by patterning the tungsten oxide layer.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain an electrochromic device which prevents deterioration of the constituent film of the electrochromic device and reduces color bleeding.

[0019]

In order to achieve the above-mentioned object, an electrochromic device according to a first aspect of the present invention has at least a first electrode layer laminated on a substrate and a reversible electrolysis. An electrochromic device comprising an oxide layer or an oxidative coloring electrochromic layer, an ionic conductive layer, a reduction coloring electrochromic layer and a second electrode layer, wherein the first electrode layer and the reversible electrolytic oxidation layer or the oxidative coloring type It is characterized in that an insulating layer for electrons and ions is selectively provided between the electrochromic layer and the electrochromic layer.

The electrochromic device according to the invention of claim 2 is at least a first electrode layer laminated on a substrate, a reversible electrolytic oxidation layer or an oxidative coloring electrochromic layer, an ion conductive layer, In an electrochromic device comprising a reduction coloring electrochromic layer and a second electrode layer, an insulating layer for electrons and ions is selected between the reversible electrolytic oxidation layer or the oxidation coloring electrochromic layer and the ion conductive layer. It is characterized in that it is provided specifically.

[0021]

The electrochromic device according to the present invention has at least a first electrode layer, a reversible electrolytic oxidation layer or an oxidative coloring electrochromic layer, an ion conductive layer, and a reduction coloring electrochromic layer on a substrate. A layer, a second electrode layer, and an insulating layer are stacked.

The first electrode layer is laminated on the substrate. Further, the reversible electrolytic oxidation layer or the oxidative coloring type electrochromic layer, the ion conductive layer, the reduction coloring type electrochromic layer and the second electrode layer are sequentially stacked on the first electrode layer.

Here, the insulating layer is selectively provided between the first electrode layer and the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer.

That is, the insulating layer comprises the reversible electrolytic oxidation layer or the oxidative coloring type electrochromic layer, the ion conductive layer, the reduction coloring type electrochromic layer and the second electrode layer on the first electrode layer. Before stacking, the patterns are stacked in the reverse pattern of the pattern forming the display unit.

Therefore, the reversible electrolytic oxidation layer or the oxidative coloring type electrochromic layer, the ion conductive layer, and the reduction coloring type electrochromic layer can be continuously vacuum laminated, and are not exposed to an etching solution or a resist stripping solution. Therefore, deterioration of the electrochromic element is prevented.

The insulating layer may be formed by a lift-off method in which a photoresist pattern is formed, an insulating thin film is formed, and then the photoresist is removed to form the pattern. Alternatively, after the insulating layer is formed, Alternatively, a method of applying a photoresist, patterning, and selectively etching (dry or wet) the insulating layer may be used. In general, etching can achieve finer patterning and leaves less resist after the process.

The insulating layer is selectively provided between the first electrode layer and the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer, and the first and second insulating layers are provided.
The transfer of electrons and ions in the electrochemical reaction occurring in the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer, the ion conductive layer and the reduction coloring electrochromic layer is prevented by the external voltage applied between the electrode layers.

Therefore, the color is colored only in the desired colored part (the part without the insulating layer), and the color is prevented from bleeding in the part other than the desired colored part.

According to a second aspect of the present invention, in an electrochromic device, at least a first electrode layer, a reversible electrolytic oxidation layer or an oxidative coloring type electrochromic layer, an ion conductive layer, and a reduction coloring type electrochromic layer are provided on a substrate. A layer, a second electrode layer, and an insulating layer are stacked.

The first electrode layer and the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer are laminated on the substrate. Further, the ion conductive layer, the reduction coloring electrochromic layer and the second electrode layer are sequentially stacked on the first electrode layer.

Here, the insulating layer is selectively provided between the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer and the ion conductive layer, and is provided between the first and second electrode layers. The applied external voltage blocks the movement of electrons and ions in the electrochemical reaction occurring in the reversible electrolytic oxidation layer or the oxidative coloring type electrochromic layer, the ion conductive layer and the reduction coloring type electrochromic layer.

Therefore, it is possible to prevent the color from bleeding only in the desired colored portion, and to prevent the color other than the desired colored portion from bleeding.

The insulating layer is selectively provided between the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer and the ion conductive layer.

Therefore, since it is not necessary to pattern the reversible electrolytic oxidation layer or the oxidative coloring type electrochromic layer, problems associated with conventional patterning such as resist residue and edge spots can be solved and a device can be stably formed. It becomes possible to do.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view showing a schematic structure of an electrochromic device (hereinafter referred to as "EC device") according to an embodiment of the present invention. The case used in a camera finder will be described below. To do. As shown in FIG. 1, the EC device according to this embodiment has a lower transparent conductive film (ITO; first electrode layer) having a sheet resistance of about 10 Ω / □ on the entire surface of a glass substrate 1 for a finder having a thickness of about 1 mm. 2 is laminated on the substrate 1 by sputtering to a thickness of about 0.2 μm.

Then, after patterning by etching in a shape corresponding to the electrode extraction of the first and second electrode layers, a transparent silicon dioxide film (insulating material) having an electron and ion insulating property is formed on the entire surface of the lower transparent conductive film 2. Layer 7 is formed to a thickness of about 0.5 μm. After that, a positive type resist FPR-500 (manufactured by Tokyo Ohka) is applied on the entire surface of the silicon dioxide film 7 by spin coating, and the silicon dioxide film 7 and the resist are patterned by mask adhesion, exposure and development. The resist is removed by etching with an etchant (hydrofluoric acid) to form a pattern of the silicon dioxide film 7 on the lower transparent conductive film 2. As a result, the silicon dioxide film 7 is selectively provided on the lower transparent conductive film 2. The pattern on the silicon dioxide film 7 becomes a portion (non-display portion) where the EC element is not subjected to color fading / decoloring.

Then, on the silicon dioxide film 7 and the lower transparent conductive film 2, a film of iridium oxide or the like (a reversible electrolytic oxidation layer or an oxidation coloring electrochromic layer) 3,
A tantalum oxide film (an example of an ion conductive layer) 4, a tungsten oxide film (reduction coloring electrochromic layer) 5 and an upper transparent conductive film (ITO; second electrode layer) 6 are successively formed by vacuum vapor deposition. The thickness of each laminated layer is about 0.1 μm, 0.7 μm, 0.5 μm, 0.2 μm.
m. Finally, a sealing glass (not shown) was attached to the entire surface of the upper transparent conductive film 6 using an epoxy resin to form an EC element.

In the EC device formed as described above, by applying a voltage between the lower transparent conductive film 2 and the upper transparent conductive film 6, the iridium oxide film 3, the tantalum oxide film 4, and the tungsten oxide film are formed. The so-called E of the membrane 5
An electrochemical reaction occurs in the C3 layer, and the migration of electrons and ions causes the tungsten oxide film 5 to be colored blue. When the voltage is applied in the reverse direction, the color disappears.

Since the silicon dioxide film 7 is formed between the lower transparent conductive film 2 and the iridium oxide film 3 in the EC3 layer corresponding to the portion where the silicon dioxide 7 is formed. In the above, since there is no movement of electrons and ions in the film thickness direction, a coloration / discoloration reaction does not occur, color bleeding or color residue is eliminated, and an EC element capable of clear coloration / discoloration is obtained.

Further, since the EC3 layer can be continuously formed by vacuum evaporation, it is possible to prevent deterioration of the constituent film of the EC element. In addition, since the patterning is performed by the silicon dioxide film 7, the resist residue and the like are reduced, and the leak current can be reduced.

Here, in the first embodiment,
The following problems may occur. This is because the iridium oxide film 3 has some conductivity immediately after it is formed, and therefore an electric field is applied to the iridium oxide film 3 through the iridium oxide film 3 even at the portion where the silicon dioxide film 7 is provided. This is a problem that decolorization (color bleeding) may occur. This phenomenon is alleviated because the iridium oxide film 3 is oxidized by the initial application of electricity to carry out the coloration / decoloration operation and is electrically insulated (this process is called initialization). In order to prevent this phenomenon, as shown in FIGS. 2A and 2B, the shape of the silicon dioxide film 7 is changed from the lower surface on the lower transparent conductive film 2 side to the upper surface on the iridium oxide film 3 side. The conductive communication passage 8 (9) of the iridium oxide film 3 is formed wide.
It can be solved by shortening the interval.

In FIG. 2, (A) is a schematic partial enlarged view of the EC element in the first embodiment, and (B).
FIG. 4 is a schematic partial enlarged view of an EC element when the shape of the silicon dioxide film 7 is modified.

FIG. 3 is a sectional view showing a schematic structure of an EC device showing a modified example of the first embodiment. The modification of the first embodiment is that, as shown in FIG. 3, the lower transparent conductive film 2 is formed in an uneven shape, and the silicon dioxide film 7 is provided in the concave portion of the lower transparent conductive film 2. The EC element is configured as follows. Except for this, since the EC element is formed as in the first embodiment, the same parts are designated by the same reference numerals and the description thereof is omitted.

In this way, as shown in FIG. 3, even if the silicon dioxide film 7 is arranged in the concave portion of the transparent conductive film 2 having an uneven surface to form an EC element, the first element is formed. The same effect as the embodiment can be obtained.

FIG. 4 is an EC showing a second embodiment of the present invention.
It is sectional drawing which shows schematic structure of an element. The difference from the first embodiment is that the formation position of the silicon dioxide film 7 (insulating layer) is the iridium oxide film (reversible electrolytic oxidation layer or oxidative coloring electrochromic layer) 3 and the tantalum oxide film ( Ion conductive layer) 4 and thickness of about 0.3μ
The point is that the EC element is configured by selectively providing m.

That is, on the entire surface of the lower transparent conductive film 2 formed on the entire surface of the glass substrate 1 by the sputtering method,
The film 3 of iridium oxide or the like is formed by vacuum deposition,
An electron and ion insulating transparent silicon dioxide film 7 is formed on the entire surface of the iridium oxide film 3 to a thickness of about 0.3 μm. After that, a positive type resist FPR-500 (manufactured by Tokyo Ohka) is applied on the entire surface of the silicon dioxide film 7 by spin coating, and the silicon dioxide film 7 and the resist are patterned by mask adhesion, exposure, and development. The resist is removed by etching with an etching solution (hydrofluoric acid) to form a pattern of the silicon dioxide film 7 on the iridium oxide film 3. Then, the iridium oxide film 3 and the silicon dioxide film 7 are formed.
The tantalum oxide film 4 and the tungsten oxide film 5 are formed on the upper surface.
And an upper transparent conductive film (ITO; second electrode layer) 6 are continuously formed by vacuum vapor deposition, and finally a sealing glass is attached to the entire surface of the upper transparent conductive film 6 by using an epoxy resin to form an EC device. It was formed.

Thus, even if the formation position of the silicon dioxide film 7 is selectively provided between the iridium oxide film 3 and the tantalum oxide film 4, the tungsten oxide film on the silicon dioxide film 7 is formed. It is possible to suppress the spread of the electric field to the electrode 5 (leakage, arrow 10 in the figure) and reduce color fringing.

Further, since the three layers of the iridium oxide film 3, the tantalum oxide film 4, and the tungsten oxide film 5 are not formed by continuous vacuum evaporation, as compared with the first embodiment.
Although the deterioration of the constituent film of the EC element in the second embodiment cannot be reduced, since the patterning process is performed by the silicon dioxide film 7, the resist residue and the edge spots are reduced, and the EC element is stabilized. Can be formed.

In each of the above-mentioned embodiments, the opposed transmission type all-solid-state type E such as tungsten oxide-iridium oxide is used.
Although the description has been given based on the C element, the present invention is not limited to this and can be widely applied to thin film type EC elements.

Further, although the silicon dioxide film 7 is used as the insulating layer in each of the above-mentioned embodiments, the present invention is not limited to this. For example, a tantalum oxide film having a small ionic conductivity, or an insulating material which can be patterned more easily. May be used.

[0051]

As described above, according to the present invention, since the insulating layer for electrons and ions is provided in the constituent film of the EC element, it is possible to prevent the constituent film of the EC element from deteriorating and prevent color bleeding. The effect is that you can.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an electrochromic element showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing problems that may occur in the first embodiment and means for solving the problems.

FIG. 3 is a cross-sectional view showing a schematic configuration of an EC device showing a modification of the first embodiment.

FIG. 4 is a sectional view showing a schematic configuration of an electrochromic device showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... ITO transparent electrode layer (an example of 1st electrode layer) 3 ... Iridium oxide etc. film (an example of reversible electrolytic oxidation layer or oxidation coloring type EC layer) 4 ... Tantalum oxide film (of an ion conductive layer) Example: 5 ... Tungsten oxide film (an example of a reduction coloring type EC layer) 6 ... ITO transparent electrode layer (an example of a second electrode layer) 7 ... Silicon dioxide film (an example of an insulating layer against electrons and ions)

Claims (2)

[Claims] 1. A first electrode layer, a reversible electrolytic oxidation layer or an oxidative coloring type electrochromic layer, an ion conductive layer, a reduction coloring type electrochromic layer and a second electrode layer, which are provided at least on a substrate. In the electrochromic element, the electrochromic device is characterized in that an insulating layer for electrons and ions is selectively provided between the first electrode layer and the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer. Chromic element. 2. At least a first electrode layer, a reversible electrolytic oxidation layer or an oxidative coloring type electrochromic layer, an ion conductive layer, a reduction coloring type electrochromic layer and a second electrode layer which are laminated on a substrate. In the electrochromic element, the electrochromic element is characterized in that an insulating layer for electrons and ions is selectively provided between the reversible electrolytic oxidation layer or the oxidative coloring electrochromic layer and the ion conductive layer. .