JPH05224242A - Electrochromic display - Google Patents

Abstract

(57) [Summary] [Purpose] To achieve long life and two-color display in ECD that employs EC solution using viologen compounds. [Structure] Display is performed by using an electrolyte and using the redox reaction to deposit a dye on a predetermined electrode.
In CD, the general formula: An EC solution is produced using the viologen compound represented by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochromic display device in which a novel viologen compound is used to utilize its redox reaction to deposit a dye on an electrode arranged at a predetermined position to perform a display operation. It is a thing.

[0002]

2. Description of the Related Art Conventionally, a so-called electro-luminescent device has been used in which a viologen compound as an electrolyte is used and a redox reaction is used to deposit a dye on a predetermined electrode arranged at a predetermined position for display. Chromic display device (hereinafter,
Various types of ECD) have been proposed.

As the liquid type ECD, for example, a display electrode and a counter electrode are arranged in a glass container, and an aqueous solution of a viologen compound as an active material is filled in contact with these electrodes between them. Then, by applying a drive voltage between the electrodes,
The principle of operation is to cause a redox reaction in a viologen compound, deposit a dye by radicals formed on an electrode plate, and use this for display.

As a viologen compound to be filled in the green ECD based on such a principle, an aqueous solution system using p-cyanophenyl viologen represented by the chemical formula 4 is known.

[Chemical 4]

[0005]

However, in the aqueous solution system of p-cyanophenyl viologen and a salt, it was difficult to maintain the color fading reaction about several tens times. If the reversible reaction cannot be maintained for a long time, it is not practical as a display device.

Further, a ferrocyanine compound is added to this aqueous solution system to precipitate crystals, and then a large amount of potassium chloride (KCl) is added to redissolve the precipitate and thereby make the solution transparent. However, in this case, the reduction potential is low and the display response speed to the display drive voltage is slow. Furthermore, when driven by the second reduction potential, the reversible reaction does not proceed well. That is, it is possible to change the display color only for a single color, and it is not possible to realize a two-color display.

Further, in an aqueous solution system of p-cyanophenyl viologen, a ferrocyanine compound and a salt, a black-purple precipitate may be generated during display driving or while standing, depending on lack of deoxidation and the concentration of added salt. Yes, that is, the stable region where precipitates did not occur was narrow and it was not easy to handle.

[0008]

The present invention has been made in view of the above problems, and maintains a reversible reaction for about 1000 cycles, and also enables a two-color display as a reversible reaction in the second reduction reaction. The present invention provides an ECD using a novel viologen compound suitable for use as an electrochromic liquid.

That is,

[Chemical 5] In viologen compound used represented, an aqueous solution system prepared by adding salt to the viologen compound (0.001 mol to 0.3 mol concentration range), hypophosphite ion (H ₂ P
O ₂ ^-) and / or chlorine ions (Cl ^-) and / or bromine ion (Br ^-) ion concentration ranges by 0.1 mol to 2.3
It produces an aqueous solution system that is less than or equal to molar.

The viologen compound of the above (Chemical Formula 5) (
0.001 mol to 0.3 mol concentration range), an aqueous solution of ferrocyanide compounds of the following concentration ranges 0.3 mol 0.001 mol or more, an aqueous solution system with added salt, hypophosphorous acid ion (H ₂ PO ₂ ^- ) and / or chlorine ions (Cl ^-) and /
Or bromine ion (Br ^-) ion concentration ranges by to form an aqueous solution system is 2.3 mol or less 0.05 mol or more.

Then, EC is adopted as an electrochromic liquid (EC liquid) which is filled between the counter electrodes, at least one of which serves as a display electrode, in contact with these electrodes.
Configure D.

[0012]

In the aqueous solution system in which a salt is added to the viologen compound shown in (Chemical formula 5), a good color-decoloring reaction was observed after 1000 cycles. In addition, a good reversible reaction was observed in the second reduction reaction in the above aqueous solution system of the viologen compound, the ferrocyanine compound and the salt.

[0013]

EXAMPLE As shown in FIGS. 1 and 2, the structure of the ECD according to the present invention is such that two glass substrates 1 and 2 are opposed to each other through a spacer 3 provided along the periphery thereof. A liquid-tight space is formed between the glass substrates 1 and 2 which are sealed. Then, the EC liquid 8 is filled in the liquid-tight space.

Electrodes 4 and 5 are entirely deposited on the inner surfaces of the glass substrates 1 and 2, respectively, and insulating layers 6 and 7 made of, for example, a SiO ₂ layer are coated on the electrodes 4 and 5, respectively. .. At least one of the electrodes 4 and 5 is a transparent electrode made of, for example, ITO (composite oxide of In and Sn), and both electrodes 4, 5
The upper insulating layers 6 and 7 are provided with through holes 6a and 7a corresponding to the pattern to be displayed. In the example shown, "F
Through holes 6a and 7a having a pattern of "M" and "AM" are formed.

Further, for example, different side edges 1a and 2a of the glass substrates 1 and 2 are provided outside so as not to face the other glass substrate (2, 1), and these side edges are formed. Electrodes 1 and 2a are respectively coated with electrodes 4 and 5 or a conductive layer which is connected to these electrodes 4 and 5, and terminal portions 4a and 5a are led out.

In this embodiment, in the liquid-tight space between the glass substrates 1 and 2 described above,

[Chemical 6] A viologen compound represented by, that is, a solution using 4- (p-cyanophenyl) -4′-heptylbipyridinium bromide chloride (hereinafter abbreviated as cyanophenylheptylviologen) as an EC liquid. is there.

Then, the liquid-tight space is filled with an EC liquid, and a DC voltage is applied to both electrodes 4 and 5, and the polarities thereof are reversed, so that each electrode 4 is inverted.
Windows 6 not covered by insulating layers 6 and 7 of
dark green coloring occurs in a and 7a, which causes "F
Switching display of "M" and "AM" is realized.

Various characteristic data obtained for various examples of EC solutions according to the present invention will be shown below. The voltammogram and the change in transmittance of the EC solution were measured using the EC cell 32 shown in FIG. The EC cell 32 includes a pair of counter electrodes 10 and 11 in a container 9 containing an EC liquid 8.
And the reference electrode 14 are permeated. One electrode 10
Is an IT that has a sheet resistance of 30Ω / □ on a glass substrate.
O transparent conductive layer 12 is applied, and a 1 cm ² window 1
3a is covered with an SlO ₂ insulating layer 13 having a hole. The other electrode 11 was made of a 4 cm ² platinum plate, and the reference electrode 14 was a silver / silver chloride electrode. Window 13 of electrode 10
A spectrophotometer was used for the change in transmittance due to coloring-decoloring in a. Further, the measurement of the coloring density and the time response speed of the electric current was performed using the optical system shown in FIG. 31 is a light source,
32 is the EC cell of FIG. 3, 33 is a diaphragm, 34 is a monochromator, 35 is a photomultiplier tube, 38 is a digital memory, 37 is an XY recorder, 38 is a power supply, and 39 is a current probe.

First, as an EC solution, a composition having the following composition: cyanophenylheptylviologen ... 0.01 mol.potassium chloride (KCl) .1.0 mol was poured into the container 9 as shown in FIG. FIG. 5 shows a voltammogram when the voltage applied between the electrodes 10 and 11 is + 0.4V to −0.4V at a voltage sweep rate of 30 mV / sec. That is, it represents a redox reaction by cyanophenylheptyl viologen according to the present invention, and the applied voltage of -0.2 which is a portion where the current sharply decreases.
Reduction occurs near V and coloring (green) becomes effective,
Further, it can be seen that electron emission is performed and decoloring is performed in the portion where the current sharply rises. This redox reaction was well reversible up to about 1000 cycles. That is, for ECD, it is understood that cyanophenylheptylviologen is a suitable material for use as an EC liquid.

Next, an EC solution is an aqueous solution system prepared by adding salts to an aqueous solution of cyanophenylheptylviologen and potassium ferrocyanide (K ₄ Fe (CN) ₆ ). The composition is: cyanophenylheptyl viologen: 0.01 mol, potassium ferrocyanide: 0.01 mol, potassium chloride (KCl): 1.0 mol, sodium hypophosphite (NaH ₂ PO ₂ ).・ ・ ・ ・ ・ 1.0 mol. The solution is vacuum degassed and is free of dissolved oxygen.

Although the solution of cyanophenylheptylviologen and potassium ferrocyanide has a blue-green color, it is possible to make the solution transparent by adding and dissolving a predetermined amount of potassium chloride in the solution. The difference in the clearing effect depending on the amount of potassium chloride added is shown in FIG. That is, curve A has a potassium chloride addition of 0 mol, curve B has a potassium chloride addition of 0.05 mol, and curve C has a potassium chloride addition of 0.55 mol.
It is shown at wavelengths between m and 900 nm. It is understood from FIG. 6 that the solution of cyanophenylheptylviologen and potassium ferrocyanide becomes almost transparent when the amount of potassium chloride added is 0.55 mol or more.

Various measurement results when the applied voltage is scanned up to the first reduction potential for the EC liquid having the above composition will be described with reference to FIGS. 7 to 11. FIG. 7 shows the voltage applied to the cell 32 in the above measurement method as shown in FIG.
This is the measurement result of wavelength-transmittance when driven with a rectangular wave voltage with a pulse width of 0.6 sec at 1.0 sec and a pulse width of -0.53 V at 3.0 sec.

According to this, in the reduced state, a high transmittance is shown near 530 nm, that is, near the wavelength of green, in the range of 700 nm or less, which shows high visual sensitivity to the naked eye. That is, it can be seen that in the reduced state, the electrode 10 is colored and displayed in green.

FIG. 9 shows the voltage applied to the cell 32 as shown in FIG.
FIG. 11 is a voltammogram when a triangular wave voltage of +0.8 V to −0.4 V such as 0 is set, and FIG. 11 shows the transmittance at a wavelength of 600 nm at the time of this voltage scan. In addition, in FIGS. 9 to 11, each of ~ indicates a value at the same point.

When the applied voltage is swept in the positive direction in the positive direction, the oxidation reaction of potassium ferrocyanide occurs first, and subsequently, when the sweep of the applied voltage changes to the negative direction, the reduction reaction of potassium ferrocyanide occurs. Can be understood from FIG. 9, but no change in transmittance is observed during this period, as can be seen from FIG. That is, there is no coloration / decoloration reaction of the solution.
However, the sweep in the negative direction fell into the negative potential range, and after the time point in the figure was reached, a sharp decrease in current was observed.
The transmittance is also changing. That is,

[Chemical 7] It can be seen that the coloring is performed by the reduction reaction of cyanophenylheptylviologen shown as the reaction from the left side to the right side in. At the time of, the deepest coloring is recognized.

Thereafter, when the sweep of the applied voltage shifts to the positive direction, the color fades due to the oxidation of cyanophenylheptylviologen shown as the reaction from the right side to the left side in the chemical formula (Formula 7), and the color disappears at the time. Is achieved.

Next, various measurement results when the applied voltage is scanned up to the second reduction potential for the EC liquid having the above composition will be described with reference to FIGS. Figure 12
The voltage applied to the cell 32 is + 0.7V potential as shown in Fig. 13.
It is the measurement result of the wavelength-transmittance when driven with a rectangular wave voltage with a pulse width of 1.5 sec and a pulse width of -0.8 V of 2.5 sec. In FIG. 12, the envelope at the lower end shows the first reduction state, and the envelope in the middle shows the second reduction state.

According to this, 70 which shows high visibility with the naked eye
In the range of 0 nm or less, the first reduced state shows high transmittance near 530 nm, that is, near the green wavelength, and the second reduced state shows relatively high transmittance in the range of 530 nm to 700 nm. That is, it can be seen that the electrode 10 is colored in green in the first reduced state, and the electrode 10 is colored in reddish purple in the second reduced state.

FIG. 14 is a voltammogram when the voltage applied to the cell 32 is a triangular wave voltage of +0.8 V to -0.7 V as shown in FIG. 15, and FIG. 16 is a transmission at 600 nm during this voltage scan. Shows the rate. 14 to 16 show values at the same time point.

As in the case of FIG. 9, when the applied voltage is swept in the positive potential range in the positive direction, the oxidation reaction of potassium ferrocyanide first occurs, and when the sweep of the applied voltage changes to the negative direction, potassium ferrocyanide is subsequently changed. The reduction reaction of 1 occurs, but the transmittance does not change during this period. That is, there is no coloration / decoloration reaction of the solution. However, after the sweep in the negative direction entered the negative potential range, and after reaching the time point in the figure, a sharp decrease in current was observed, and the transmittance also changed. That is,

[Chemical 8] It can be seen that the coloring is performed by the first reduction reaction of cyanophenylheptylviologen shown as the reaction from the left side to the right side in. That is, at this point, the electrode 10 is colored green. At that time, the deepest coloring is recognized.

After that, when the applied voltage is further swept in the negative direction,

[Chemical 9] It is clearly recognized that the second reduction reaction of cyanophenylheptylviologen shown as the reaction from the left side to the right side in (1) occurs, whereby the color displayed at the electrode 10 changes from green to red-purple between (1) and (2).

Thereafter, when the sweep of the applied voltage shifts to the positive direction, the red color is restored when the cyanophenylheptylviologen is oxidized by the reaction shown as the reaction from the right side to the left side in the chemical formula (Formula 9). The purple presentation color changes to green again, and at this point, the presentation color of the electrode 10 becomes green.

When the voltage was further swept in the positive direction, the color faded at the time of ~ due to the oxidation of cyanophenylheptylviologen shown as the reaction from the right side to the left side in the chemical formula (Formula 8), Decolorization is achieved at.

That is, the EC solution having the above composition exhibits a good reversible reaction not only in the first reduction region but also in the second reduction region. Therefore, by using this EC solution, ECD
It is understood that a two-color display of green and magenta can be realized.

Thus, an aqueous solution system in which a salt is added to an aqueous solution of cyanophenylheptylviologen and potassium ferrocyanide (K ₄ Fe (CN) ₆ ) that realizes two-color display is EC
The response speed of the liquid is shown in FIGS. 17, 19 and 21. Each of FIG. 17, FIG. 19 and FIG. 21 (a) shows the wavelength 600n at which the transmittance change width is the largest in FIG.
The response speed is indicated by the change in transmittance at m, and
9, (b) of FIG. 21 shows the response speed by changing the current.

The composition of the EC liquid at this time is: cyanophenylheptylviologen ... 0.02 mol.potassium ferrocyanide.0.02 mol.potassium chloride (KCl) ... 1.0 mol. Sodium hypophosphite (NaH ₂ PO ₂ ) ... 1.0 mol.

The data of FIG. 17 was measured by applying a voltage of + 0.44V and -0.44V at a cycle of 1 Hz as shown in FIG. Also,
The data in FIG. 19 was measured by applying voltages of +0.49 V and −0.49 V at a 1 Hz cycle as in FIG. Further, FIG. 21 shows a comparison between the cases where the applied voltage is ± 0.44 to ± 0.60.

As can be seen from these figures, by applying a negative voltage at time t ₁ , cyanophenylheptylviologen is reduced, that is, colored, but if the applied voltage is low as shown in FIG. 17, the application time is extended. However, the coloring density does not exceed a certain level. However immediately decoloring made by applying a positive voltage at t ₂ time. On the other hand, FIG.
It is observed that when the applied voltage is increased as in No. 9, the coloring density increases with the application time, but the response time becomes ambiguous. However, in any case, it is recognized that the EC liquid of this embodiment has reached a practically sufficient level as the response speed of the display operation.

Further, the EC liquid of this embodiment has a wide stable region in which no black-purple precipitate is generated during display driving or standing, and the solution is easy to prepare in the composition system, and no precipitate is generated. Therefore, the achievement of a longer life was observed.

[0040]

As described above, in the ECD of the present invention, it is understood that the performance can be remarkably improved by using the above-mentioned viologen compound (Formula 1) as the EC liquid. That is, when the EC solution is an aqueous solution of a viologen compound and a salt, a good reversible reaction of about 1000 cycles is maintained, and thus this ECD is sufficiently practical. Further, when an aqueous solution system of a viologen compound, a ferrocyanine compound and a salt is used as an EC solution, a reversible reaction of 10 ⁷ times or more is obtained, and the second reduction reaction is also recognized as a reversible reaction. Has a great effect that two-color display is possible.

[Brief description of drawings]

1 is a plan view of an embodiment of an ECD according to the present invention.

FIG. 2 is a sectional view taken along the line AA of the embodiment of the ECD according to the present invention.

FIG. 3 is a perspective view of a cell for measuring a characteristic of an EC liquid in the ECD of the present invention.

FIG. 4 is a block diagram of an optical system for measuring a characteristic of an EC liquid in the ECD of the present invention.

FIG. 5 is a voltammogram of an EC solution containing a viologen compound and a salt in the ECD of the present invention.

FIG. 6 is an explanatory view showing the effect of adding KCl 3 to an EC solution by viologen compound, ferrocyanine compound and salt in ECD of the present invention.

FIG. 7 is a wavelength-transmittance characteristic diagram when a voltage up to the first reduction potential of the EC liquid in the ECD of the present invention is applied.

FIG. 8 is a waveform diagram of an applied voltage when measuring the wavelength-transmittance characteristic of FIG. 7.

FIG. 9 is a voltammogram when an applied voltage is swept up to the first reduction potential of the EC liquid by the viologen compound, the ferrocyanine compound, and the salt in the ECD of the present invention.

10 is a waveform diagram of an applied voltage during the measurement of FIG.

11 is a measurement diagram of a change in transmittance corresponding to the measurement of FIG.

FIG. 12 is a wavelength-transmittance characteristic diagram when a voltage up to the second reduction potential of the EC liquid in the ECD of the present invention is applied.

13 is a waveform diagram of an applied voltage when the wavelength-transmittance characteristic of FIG. 12 is measured.

FIG. 14 is a voltammogram at the time of applied voltage sweep up to the second reduction potential of the EC liquid by the viologen compound, the ferrocyanine compound, and the salt in the ECD of the present invention.

FIG. 15 is a waveform diagram of an applied voltage during the measurement of FIG.

16 is a measurement diagram of a transmittance change corresponding to the measurement of FIG.

FIG. 17 is a measurement diagram of a response speed of an EC solution in the ECD of the present invention.

FIG. 18 is a waveform diagram of an applied voltage during the measurement of FIG.

FIG. 19 is a measurement diagram of the response speed of the EC solution in the ECD of the present invention.

20 is a waveform diagram of an applied voltage during the measurement of FIG.

FIG. 21 is a measurement diagram of the response speed of the EC solution in the ECD of the present invention.

[Explanation of symbols]

 1, 2 glass substrate 4,5 electrode 8 EC liquid

[Procedure amendment]

[Submission date] April 7, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

As the liquid type ECD, for example, a display electrode and a counter electrode are arranged in a glass container, and an aqueous solution of a viologen compound as an active material is filled in contact with these electrodes between them. Then, by applying a drive voltage between the electrodes,
This is a display method using an operating principle in which a redox reaction is caused in a viologen compound, color is developed by radicals deposited on an electrode plate by the reduction reaction, and radicals are ionized and decolorized by the oxidation reaction.

Claims (3)

[Claims] 1. An electrochromic display device in which an electrolyte is used and a redox reaction is utilized to deposit a dye on a predetermined electrode for display, and at least one of the electrodes is a display electrode between opposed electrodes. The electrochromic liquid filled in contact with these electrodes is represented by the general formula: An electrochromic display device comprising a viologen compound represented by: 2. An electrochromic display device in which an electrolyte is used and a redox reaction is used to deposit a dye on a predetermined electrode for display, and at least one of the electrodes is a display electrode between opposing electrodes. , In contact with these electrodes, a general formula in the concentration range of 0.001 mol or more and 0.3 mol or less, A viologen compound represented in, an aqueous solution system with added salt, hypophosphorous acid ion (H ₂ PO ₂ ^-) and / or chlorine ions (Cl ^-) and / or bromine ion ^- ion concentration by (Br) An electrochromic display device, characterized in that an aqueous solution system having a range of 0.1 mol or more and 2.3 mol or less is filled as an electrochromic liquid. 3. An electrochromic display device in which an electrolyte is used and a redox reaction is used to deposit a dye on a predetermined electrode for display, and at least one of the electrodes is a counter electrode between opposing electrodes. , In contact with these electrodes, the general formula in the concentration range of 0.001 to 0.3 mol An aqueous solution system in which a salt is added to an aqueous solution of a viologen compound represented by and a ferrocyanine compound in a concentration range of 0.001 mol or more and 0.3 mol or less, wherein the hypophosphite (H ₂ PO
₂ ^-) and / or chlorine ions (Cl ^-) and / or bromine ion (Br ^-) ion concentration ranges by is 2.3 mol or less 0.05 mol aqueous system, and characterized in that it is filled electrochromic solution Electrochromic display device.