JPH02262126A - Electrochromic display device - Google Patents

Abstract

PURPOSE:To simplify the structure of the electrochromic (EC) display device and to obtain the device having a high contrast by disposing EC materials having different characteristics to counter electrodes. CONSTITUTION:This device is constituted by disposing, for example, two sheets of the transparent electrodes 1a, 1b to face each other via a spacing, laminating EC layers 2a, 2b respectively on the opposite surfaces of the electrodes 1a, 1b exclusive of the peripheral edges thereof, disposing a spacer 3 around the electrodes 1a, 1b and providing an electrolyte layer 4 between the two EC layers 2a and 2b. An o-dialkoxy benzene polymer is used for the one EC layer 2a of the EC layers 2a, 2b. The other EC layer 2b is formed of the EC material which is lower in the light absorbance of the oxidation state than in the reduction state thereof. The construction is simplified in this way and the display device having the high contrast is obtd.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to improving the display performance of an electrochromic (hereinafter abbreviated as EC) display device. The present invention relates to an EC display device that can provide color changes.

(Prior art) The phenomenon in which the color changes when a voltage is applied to a substance is called electrochromism, and substances that exhibit such properties are called E.
It is called C substance. Furthermore, a display device using this EC material is called an EC display device.

An EC display device is generally produced by laminating an EC layer made of an EC material on a transparent electrode, and arranging a counter electrode on the EC layer side with an electrolyte layer in between.

Examples of the EC material used here include inorganic oxides, complexes, organic dyes, and conductive polymers, but in any case, when laminated on an electrode, it is necessary to maintain sufficient electrical conductivity of the EC layer. The layer thickness is limited. Furthermore, when the thickness of the EC layer is set to ensure sufficient electrical conductivity as described above, it often becomes too thin to provide sufficient contrast.

In order to eliminate such drawbacks, a method of stacking a plurality of EC material-covered electrodes may be considered. However, this method has the disadvantage of complicating the circuit configuration because it is necessary to provide the same number of opposing electrodes. On the other hand, 5ociety of
Automotive Engineers, I
nc 861362+7p (1986), an EC display device in which EC materials with different characteristics are laminated on each of opposing electrodes has been developed, and secondary effects other than contrast improvement are expected.

For example, with two electrodes ASB facing each other, an EC layer that is colorless in the oxidized state and colored in the cyclic state is laminated on A, and an EC layer that is colored in the oxidized state and colorless in the cyclic state is stacked on B. When stacked, when a voltage is applied between A and B to put the AOEC layer into the oxidized state, the BOEC layer becomes the cyclic state, so
The device as a whole becomes colorless, and when the AOEC layer is in a ring state, the BOEC layer becomes an oxidized state, so the device as a whole exhibits a color that is a combination of the colors of the colored states of each E'C layer of AlB. .

In such an EC display device, the circuit configuration can be simplified, and when the colored states of each EC layer in A and B are similar, the contrast is greater than when only a single type of EC layer is used. The display state is improved, and if the colored states are different, such as red and blue, it is possible to display a completely different color, such as purple, by superimposing them.

(Problems to be Solved by the Invention) The present inventors have developed an 0-dialkoxybenzene polymer as a new EC material, and have conducted research to apply this to display devices. An EC display device using only a polymer has a drawback that contrast is low and color unevenness tends to occur during polymerization. In addition, there is a concern that the performance of the counter electrode may deteriorate due to reactions of the electrolyte. As a result of intensive research to improve these drawbacks, the present invention was completed.

An object of the present invention is to provide an EC display device that can be simplified in structure and has high contrast.

(Means for Solving the Problems) The EC display device of the present invention is an electrochromic display device in which an electrochromic layer is provided on the inner surface of two opposing transparent electrodes, and an electrolyte layer is provided between both electrochromic layers. , one electrochromic layer is formed of an 0-dialkoxybenzene polymer, and the other electrochromic layer is formed of an electrochromic substance whose absorbance in the oxidized state is lower than that in the cyclic state, This achieves the above objective.

FIG. 1 is a sectional view schematically showing one embodiment of the present invention.

The EC display device shown here has two transparent electrodes 1a and 1b facing each other with a gap therebetween, and has an EC layer 2 on the opposing surfaces of the transparent electrodes 1a and 1b, excluding their peripheral edges.
EC layers 2a and 2b are stacked, a spacer 3 is provided around the transparent electrodes 1a and 1b, and an electrolyte layer 4 is provided between both the EC layers 2a and 2b. A DC power source 6 is connected to the two transparent electrodes 1a and lb via a polarity changeover switch 5.

By switching the polarity changeover switch 5, the positive electrode of the DC power supply 6 is connected to one transparent electrode 1a, and the positive electrode of the DC power supply 6 is connected to the other transparent electrode 1a.
When the negative electrode of the DC power supply 6 is connected to b, one transparent electrode l
The EC layer 2a formed on the transparent electrode lb becomes an oxidized state, and the EC layer 2b formed on the other transparent electrode lb becomes an oxidized state. Further, when the polarity changeover switch 5 is operated so that the negative electrode is connected to one transparent electrode 1a and the positive electrode is connected to the other transparent electrode 1b, the EC layer 2a formed on one transparent electrode la is in the ring state. and the other transparent electrode l
The EC layer 2b formed on the EC layer 2b becomes oxidized.

Here, the transparent electrodes 1a and lb can generally be formed by laminating a conductive thin film (tin oxide, indium oxide, etc.) on a transparent substrate (glass, film, etc.) by vapor deposition or other methods, and The electrolyte layer 4 can generally be formed of an electrolyte dissolved or dispersed in a solution or a polymer matrix.

In the present invention, among the EC layers 2a and 2b formed on each surface of the transparent electrodes 1a and 1b, one of the EC layers 2a has 0-
A dialkoxybenzene polymer is used.

The O-dialkoxybenzene polymer has a structural unit represented by the following general formula.

In the formula, R1 and R2 represent an alkyl group such as a methyl group, an ethyl group, or a propyl group, and R1 and R2 may be the same or different. Examples of 0-dialkoxybenzene include 0-dimethoxy Examples include benzene, 0-jethoxybenzene, 0-dipropoxybenzene and the like.

This polymer can be obtained by chemically or electrochemically polymerizing 0-dialkoxybenzene.

In particular, in the electrochemical polymerization method, the polymer can be easily obtained by dissolving zero dialkoxybenzene together with a supporting electrolyte in a solvent and then performing electrode oxidation. The 0-dialkoxybenzene polymer exhibits blue color in the oxidized state and white color in the cyclic state. (However, it is white when it is in a ring state and in a dry state, and becomes colorless when it is in a ring state and in a wet state.) One EC layer 2a made of an 0-dialkoxybenzene polymer The EC layer 2b on the counter electrode used in combination with the EC layer 2b is formed of an EC material whose absorbance in the oxidized state is lower than that in the cyclic state. Further, when the 0-dialkoxybenzene polymer is colorless in the ring state, it is preferable to use an EC substance that is also colorless. That is, it is preferably selected from EC substances that are colorless in the oxidized state and colored in the cyclic state. Among these Ec animal substances, it is preferable to use one whose color when colored is similar to that of the 0-dialkoxybenzene polymer, that is, one that shows blue color.
This is good because a clearer color change can be obtained.

Examples of such EC materials include tungsten trioxide. In addition, a color different from blue in the ring state (
For example, when an EC material exhibiting red) is used, a mixed color with the blue of the 0-dialkoxybenzene polymer can be obtained.

Examples of such EC substances include polyviologen complexes and phenanthroline iron complexes.

The EC material layer 2a made of an O-dialkoxybenzene polymer can be formed on the transparent electrode 1a by, for example, electrolytically oxidizing O-dialkoxybenzene on the transparent electrode.

An EC material-coated electrode in which this polymer is coated on the electrode is E
In the case of a single electrode coated with C material, the contrast is low, and E
This cannot be said to be sufficient as a C display device. Furthermore, even when several layers are stacked, color unevenness tends to occur, and there is a concern that the performance of the counter electrode may deteriorate due to reaction of the electrolyte. However, two types of E
These drawbacks are eliminated by combining C material-coated electrodes, and the contrast in particular is improved.
Superior properties can be obtained than when using conventional typical EC materials that exhibit the same color development tendency as 0-dialkoxybenzene polymers.

(Example) Next, the present invention will be explained in detail.

Backing ■ Top 0.3 mol/1. O-dialkoxybenzene and 0
．． 3 moles/! of EtJBF4 was dissolved in nitromethane,
Dissolved oxygen in the electrolytic solution was removed by bubbling Ar gas through the electrolytic solution for 5 minutes or more. Next, tin oxide-indium oxide evaporated glass (I
A reference electrode (Ag/Ag
A voltage of 1.5 V was applied to C1) for several seconds. By applying this voltage, the 0-dimethoxybenzene polymer was coated on the tin oxide-indium oxide vapor-deposited surface of the transparent electrode by electrolytic oxidation.

The obtained EC material-covered electrode (electrode A) was washed with nitromethane, dried, and used in an EC cell described later.

Another EC combined with this EC material coated electrode
The material-covered electrode (electrode B) was obtained by depositing tungsten trioxide on a transparent electrode made of ITO glass.

The obtained A electrode and B electrode were arranged so that their respective EC layers faced each other, and an electrolyte layer was sealed between them to form an EC cell. The electrolyte layer was prepared by dissolving 1 g of cyanoethylpoval and 0.1 g of Bt4NBF4 in 4-methyl ethyl ketone.

When the potential difference between the A electrode and the B electrode (A electrode - B electrode) of the obtained EC cell is increased to +1.5v or more, the EC cell turns dark blue; conversely, when this potential difference is decreased to -1.5v or less Then, the EC cell turned colorless. The visible absorption spectrum of the EC cell when the EC cell turns dark blue is shown by a solid line in FIG. 2, and the visible absorption spectrum of the EC cell when the EC cell turns colorless is shown by a solid line in FIG. In FIG. 2, the reason why the absorption of Examples is high is that the light blue color of the O-dimethoxybenzene polymer forming the EC material layer of the A electrode and the light blue color of tungsten trioxide forming the EC material layer of the B electrode. This is probably due to the fact that it was synthesized.

Comparison (1) An EC cell was prepared in the same manner as in the example except that the B electrode was changed to ITO glass. When the potential difference between the A electrode and the counter electrode of the obtained EC cell (A electrode and the counter electrode) is set to above +3.0V, the EC cell changes to a light blue color, and conversely, when it is set below -3.0V, it becomes colorless. changed. The visible absorption spectrum of the EC cell when the EC cell turns light blue is shown by a broken line in FIG. 2, and the visible absorption spectrum of the EC cell when the EC cell turns colorless is shown by a broken line in FIG.

l comparison ±1 In the above example, an EC cell was created in the same manner as in the above example except that the A electrode was changed to ITO glass. When the potential difference between the counter electrode and the B electrode of the obtained EC cell (counter electrode - B electrode) is set to more than +3.0V, the EC cell turns pale blue, and conversely, when it is set to -3.0V or less, it becomes colorless. It changed to The visible absorption spectrum of the EC cell when it changes to light blue is shown in Figure 2 by the dashed line, and E
The visible absorption spectrum of the EC cell when the C cell turns colorless is shown by the dashed-dotted line in FIG.

(Effects of the Invention) Since the EC display device of the present invention has high contrast as described above and has two types of EC layers, color unevenness can be eliminated and display colors can be made into various mixed colors. . Moreover, the structure can be simplified compared to the case where several EC material electrodes of the same type are stacked.

Figure 1 is a schematic cross-sectional view of an electrochromic display device showing one embodiment of the present invention, and Figure 2 is a diagram showing the visible absorption when colored, showing the effect of implementing the present invention in comparison with a comparative example. The spectra in Figure 3 are the same (visible absorption spectra when colorless).

1a and 1b...transparent electrode, 2a and 2b...
Electrochromic layer, 4... electrolyte layer.

that's all

Claims (1)

[Claims] 1. In an electrochromic display device in which electrochromic layers are provided on the inner surfaces of two opposing transparent electrodes, and an electrolyte layer is provided between both electrochromic layers, one electrochromic layer is made of an o-dialkoxybenzene polymer. an electrochromic display device, wherein the other electrochromic layer is formed of an electrochromic material whose absorbance in an oxidized state is lower than that in its cyclic state.