JP3000640B2 - Electrochromic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrochromic element used for a display device or light control glass.

(Prior Art) Electrochromic devices have applications such as display devices or light control glass, and research and development are being actively conducted. As shown in FIG. 3, an electrochromic element which has been studied so far has a display electrode 2 provided on a substrate 1 and an electrochromic material 3 provided on the surface thereof.
Are fixed to each other, a substrate 1 having a counter electrode 5 is bonded thereto via a spacer 6, and an electrolyte 4 is sealed between the two substrates 1. However,
In the electrochromic device having the above structure, when the area is increased, color unevenness occurs, the color change is slow, the power consumption is large, the problem on the device such as heavy, or the sealing method is difficult. There were problems. Further, an electrochromic element using a solid electrolyte, which has been actively researched and developed in recent years, as the electrolyte 4 has also been proposed. However, in such an element,
When the film thickness of the electrolyte 4 is not uniform, the solid electrolyte due to an external temperature change is placed between the display electrode 2 which fixes the electrolyte 4 and the electrochromic material 3 on its surface or between the electrolyte 4 and the counter electrode 5. There is a problem that a gap is formed due to expansion / contraction of the element or a force applied to the element from the outside, and this causes a color residue or color unevenness. Further, it is difficult to manufacture such an element with the electrolyte 4 having a uniform film thickness.

(Problems to be Solved by the Invention) It is an object of the present invention to provide an electrochromic device which has less color unevenness, has a fast color change, is resistant to changes in the external environment, and is easy to manufacture.

(Means for Solving the Problems) The present inventors have conducted intensive studies to solve the above problems, and as a result, by patterning the display electrode and the counter electrode in a comb shape, both are provided on the same substrate. It has been found that by fixing an electrochromic material on a display electrode, an electrochromic element exhibiting excellent characteristics and having an easy manufacturing method can be obtained, and the present invention has been completed. That is, the present invention has, on the same substrate, a display electrode patterned in a comb shape and a counter electrode patterned in a comb shape so as to be combined with the display electrode, and an electrochromic material is fixed on the display electrode surface. An electrochromic device characterized by: Hereinafter, the present invention will be described in more detail.

1 and 2 are a plan view and a sectional view, respectively, showing an example of the structure of the electrochromic device of the present invention. The display electrode 2 and the counter electrode 5 of the electrochromic device of the present invention are formed on the substrate 1 by patterning in a comb shape so as to be combined with each other as shown in FIG. Also,
The cross section of the display electrode 2 and the counter electrode 5 of the device shown in FIG. 1 which are combined in a comb shape is shown in FIG. 2. In the device of the present invention, the electrochromic material 3 is displayed as shown in FIG. A material 7 is fixed on the surface of the electrode 2 and a material 7 that reversibly accepts ions and electrons is fixed on the surface of the counter electrode 5.

Patterning of the display electrode 2 and the counter electrode 5 in the electrochromic device of the present invention can be performed by a usual lithography technique or screen printing technique. That is, a resist is applied on a transparent conductive film formed by an appropriate method on the surface of the substrate 1 by a method such as spin coating or screen printing, and after drying the resist, a photomask patterned into a comb shape is applied. After exposing and developing, the transparent electrode is peeled off by an etching method, and then the resist is removed, whereby a substrate having the display electrode 2 and the counter electrode 5 patterned in a comb shape can be obtained. Techniques and materials for using these steps are not particularly limited, and may be general ones.
The electrode width of the display electrode 2 or the counter electrode 5 patterned in a comb shape depends on the application and the size of the element. However, if the electrode width is too wide, there is a possibility that a color change speed is reduced or color unevenness occurs. Since it may be difficult to fix the electrochromic material on the electrode surface, it is preferable that the thickness be about 0.1 mm to 100 mm. Further, the display electrode 2 and the counter electrode 5
If the width between the electrodes is too large, the effective electrode surface area will be small and the contrast will be reduced, and the resistance between the electrodes will be large, which may lead to a reduction in the color change speed and an increase in power consumption. On the other hand, if the width is too narrow, the yield may be reduced when the electrodes are formed, or a short circuit may occur when the electrochromic material is fixed on the surface of the electrode 2, and the contrast may be reduced due to this. Therefore, the width between electrodes is
It is preferable that the thickness be about 0.05 mm to 10 mm.

The method for fixing the electrochromic material 3 on the surface of the display electrode 2 is not particularly limited. However, since the amount and thickness of the electrochromic material can be easily controlled, it is preferable to employ an electrolytic deposition method. According to this method, the electrochromic material used is not limited as long as it is deposited on the electrode surface by electrolytic oxidation or electrolytic reduction. For example, examples of the organic substance deposited on the electrode surface by electrolytic oxidation include a five-membered heterocyclic compound represented by pyrrole and thiophene and derivatives thereof, an aromatic compound having an amino group represented by aniline and derivatives thereof. Organic substances having a vinyl group such as poly (N-vinylcarbazole) can be given as examples of the organic substance that can be deposited on the electrode surface by electrolytic reduction. Further, a substance obtained by fixing a viologen or a bathophenanthroline complex exhibiting electrochromic properties in an electrochemically inactive support film obtained on an electrolytic surface by an electrolytic polymerization method can also be used as an electrochromic material. Further, as inorganic substances, Prussian blue and its analogs precipitated on the electrode surface by electrolytic reduction, tungsten trioxide, molybdenum trioxide, vanadium pentoxide or iridium oxide, cobalt, nickel deposited on the electrode surface by electrolytic oxidation, A transition metal oxide such as manganese can be used as the electrochromic material. On the other hand, a material 7 having the ability to reversibly accept the transfer of ions and electrons accompanying the oxidation-reduction reaction of the electrochromic material is fixed on the counter electrode 5. Examples of the material include an oxidation-reduction pair exhibiting no electrochromic properties, an oxidation-reduction pair having poor coloring efficiency, and an electrochromic material which develops a color by a reverse reaction with an electrochromic material fixed on an electrode. The method for fixing these materials is not particularly limited, either, but the electrolytic deposition method is preferably employed because the materials can be easily fixed.

The electrolyte 4 used in the electrochromic device of the present invention is not particularly limited as long as it has a sufficiently stable potential phase and appropriate ionic conductivity for driving the device. For example, a liquid obtained by adding perchlorates, sulfates, hexafluorophosphate, trifluoromethylsulfonate, or tetrafluoroborate as a supporting electrolyte to a polar solvent such as water, acetonitrile, propylene carbonate, or γ-butyrolactone. A type electrolyte can be exemplified. In addition, not only the liquid electrolyte described above, but also inorganic solid electrolytes such as β-alumina and tantalum oxide, organic solid electrolytes such as polyethylene oxide and propylene oxide containing electrolytes such as lithium perchlorate, and poly (2-acrylamide- Semi-solid polymer electrolytes such as 2-methylpropanesulfonic acid), Nafion (trade name, manufactured by DuPont), and polystyrenesulfonic acid. The element of the present invention
The display electrode and the counter electrode are patterned in a comb shape, and they are fixed to each other at a short distance on the same substrate.
Therefore, when the device of the present invention is manufactured using the above-described solid or semi-solid polymer electrolyte, the electrolyte may be present between the display electrode and the counter electrode, and the uniformity of the electrolyte film thickness is particularly high. It doesn't matter.

Further, the electrochromic device of the present invention having the above structure is used in a sealed state. When a liquid electrolyte is used, this sealing method employs a generally used sealing method using a spacer. In addition, when a solid or semi-solid electrolyte is used, the electrolyte can be handled as a single film, so that sealing can be performed by a simple method such as sandwiching it with a laminate film.

(Examples) The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 ITO (indium-tin oxide) having a surface resistance of 10Ω / □
An electrode was provided on the substrate 1, a photoresist was applied on the surface of the ITO electrode by a spin coating method, dried, and then exposed and developed through a photomask. After development
After the ITO was etched in a hydrochloric acid-nitric acid aqueous solution, the resist was stripped off, and a display electrode 2 and a counter electrode 5 patterned on a substrate 1 as shown in FIG. 1 were obtained. The width of these electrodes was 0.5 mm, and the width between the electrodes was 0.1 mm.

Next, a lead is taken from the electrode 2 formed on the substrate 1,
The substrate 1 was transferred into an aqueous solution containing 20 mM iron (III) chloride and 20 mM potassium ferricyanide, and a blue Prussian blue film was formed on the display electrode 2 by an electrolytic reduction method. Subsequently, a lead was taken out from the counter electrode 5 and a blue molybdenum oxide film was obtained on the counter electrode 5 by an electrolytic reduction method in a sulfuric acid aqueous solution containing 10 mM lithium molybdate. Thereafter, after both electrodes were sufficiently dried, an acetonitrile solution containing polyethylene oxide and lithium perchlorate was applied and air-dried to form an electrolyte 4, thereby producing an electrochromic device. This element was sealed by sandwiching it with a laminate film and heating.

Next, -1.5 V with respect to the counter electrode 5 of the obtained device.
When the voltage was applied, the device became transparent, and when +1.5 V was applied, the device turned dark blue. Further, when the circuit was opened in this state, no change was observed in the color of the element even after 50 hours, and no change was observed in the color change speed and color tone of the element even after repeating the above voltage change 5000 times. Was.

Example 2 In the same manner as in Example 1, a display electrode 2 and a counter electrode 5 patterned in a comb shape on the substrate 1 were obtained. Next, a lead was taken from the display electrode 2 side, and the substrate 1 was acidified with 0.1 M N, N-dimethylaniline, 10 mM bathophenanthroline sulfonate and 0.5 M sodium sulfate (pH =
1) and colorless poly (N, N
-Dimethylaniline) -vasophenanthroline iron sulfonate composite film was obtained on the surface of the display electrode 2;
Was transferred to an aqueous sulfuric acid solution and reduced, and the resulting film turned red. Subsequently, a lead was taken from the counter electrode 5 side, the substrate 1 was transferred to an aqueous solution containing 10 mM manganese sulfate and 0.1 M sodium sulfate, and subjected to electrolytic oxidation to obtain a brown manganese oxide film on the counter electrode 5. Then, after both electrodes were sufficiently dried, a liquid Nafion (trade name, manufactured by DuPont) was applied and air-dried to form an electrolyte 4, thereby producing an electrochromic device. The device was sealed by sandwiching the device with a laminate film and heating.

Next, +1.5 V with respect to the counter electrode 5 of the obtained device
When the voltage was applied, the device became transparent, and when -1.5 V was applied, the device turned dark brown. Further, when the circuit was opened in this state, no change in the color of the device could be confirmed even after 25 hours. Even after the above voltage change was repeated 3000 times, no change was observed in the color change speed and color tone of the device.

Example 3 A display electrode and a counter electrode were obtained on a substrate in the same manner as in Example 1. Next, take the lead from the display electrode side and set the board to 0.
The solution was transferred to an acidic aqueous solution (pH = 1) containing 1M aniline and 0.5M sodium sulfate, and subjected to electrolytic oxidation to obtain a green polyaniline film on the display electrode surface. In addition, place a spacer at the end of the counter electrode, further place a glass plate on it,
The periphery was sealed with an epoxy adhesive to obtain an electrochromic device. Note that an acidic aqueous solution (pH = 1) containing 0.5 M sodium sulfate was used as the electrolyte, and the space was filled between the substrate and the glass plate.

Next, when +2.5 V was applied to the counter electrode of the obtained device, the device turned blue, and when -2.5 V was applied, the device turned light yellow. Further, when the circuit was opened in this state, no change in color was observed even after 25 hours, and no change was observed in the color change speed and color tone of the element even after the above voltage change was repeated 3000 times.

(Effects of the Invention) As is clear from the above description, the electrochromic device of the present invention has little color unevenness, has a fast color change, and is resistant to changes in the external environment. Furthermore, when a solid or semi-solid electrolyte is used as the electrolyte, uniformity of the film thickness distribution does not matter so much, and the electrolyte can be handled as a film integrated with the substrate. Very simple.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of the structure of the electrochromic device of the present invention. FIG. 2 is a sectional view showing an example of the structure of the electrochromic device of the present invention. FIG. 3 is a sectional view showing the structure of a conventional electrochromic device. In the drawing, 1... Substrate, 2... Display electrode 3... Electrochromic material 4... Electrolyte, 5... Counter electrode 6... Spacer 7.

Claims (1)

(57) [Claims] 1. A display device comprising a display electrode patterned in a comb shape and a counter electrode patterned in a comb shape so as to be combined with the display electrode on the same substrate, wherein an electrochromic material is fixed on the display electrode surface. An electrochromic device, comprising: