JPH0434132B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is an electrochromic substance that
Poly4,4'-triphenylamine, poly4,4'-
(4″-methyl)triphenylamine or poly4,
This invention relates to an electrochromic display element using a reaction product of 4'-(4''methoxy)triphenylamine and an oxidizing agent.

(Prior art) Conventionally, an electrochemical redox reaction is performed in which a display electrode made of an electrochromic material film formed on transparent electrodes provided on a pair of transparent substrates and a counter electrode are opposed to each other via an electrolyte. Display elements using electrochromic materials include tungsten oxide and Prussian blue (Japanese Patent Laid-Open No. 57-158282).
Inorganic materials such as polythiophene, poly-4,
4′triphenylamine, poly4,4′-(4″methyl)
Triphenylamine, poly4,4′-(4″methoxy)
Those using conductive polymer materials such as triphenylamine are known.

(Problems to be Solved by the Invention) In the case of the above-mentioned electrochromic display element, when forming an electrochromic material layer, large-sized equipment such as evaporation or sputtering is required for tungsten oxide. In addition, since Prussian blue, polythiophene, etc. require equipment for electrodeposition and electrolytic polymerization, the equipment becomes large-scale, and it is difficult to form a uniform film over a large area. . Also, poly 4,4' triphenylamine, poly 4,4'-
(4″methyl)triphenylamine or poly4,
In the 4′-(4″methoxy)triphenylamine thin film,
Although it is easy to increase the area, there is a problem that in a colored state, the membrane dissolves into the electrolyte, resulting in poor durability.

(Means for Solving the Problems) The present invention uses poly-4,4'-triphenylamine, poly-4,
A reaction product obtained by dissolving 4′-(4″methyl)triphenylamine or poly4,4′-(4″methoxy)triphenylamine in a polar solvent, coating it on a transparent conductive film, and then exposing it to an oxidizing agent. The above problem is solved by using .

poly 4,4'-triphenylamine, poly 4,
4′-(4″methyl)triphenylamine and poly4,4′-(4″methoxy)triphenylamine are
This was proposed by the present applicant in Japanese Patent Application No. 59-148868, and was used as a conductive polymer material. These polymers use 4,4'-(4''-unsubstituted or methyl or methoxy substituted) triphenylamine as a starting material, and an intermediate (Grinard reagent) made of this compound and metallic magnesium.
It is obtained by polymerization using a nickel catalyst such as dichloronickel. In addition to chloroform, the polar solvent used to dissolve the polymer in this invention includes benzene, dichloromethane, acetone, and the like. After applying a solution dissolved in one of these solvents onto a transparent electrode, the reaction product obtained by reacting with an oxidizing agent becomes hardly soluble in the electrolytic solution and maintains sufficient electrochromic properties. As the oxidizing agent, a halogen compound, a halogen such as iodine, antimony pentafluoride, arsenic pentafluoride, etc. can be used.

An electrochromic compound consisting of a reaction product of the above-mentioned poly-4,4'-triphenylamine, poly-4,4'-(4"methyl)triphenylamine or poly-4,4'-(4"methoxy)triphenylamine and an oxidizing agent. A transparent electrode provided with a transparent material film is used as a display electrode and/or a counter electrode. An electrochromic display element using such electrodes is manufactured by sealing an electrolytic solution between the electrodes using a sealing material according to a conventional method. The electrolyte solution used at this time is
LiClO ₄ , LiBF ₄ , LiPF ₆ , KClO ₄ , KBF ₄ ,
KPF ₄ , N(C ₂ H ₅ ) ₄ ClO ₄ etc., acetonitrile,
Some are dissolved in solvents such as propylene carbonate and N,N'-dimethylformamide.

(Examples) The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 An electrochromic display element was prepared using a reaction product of poly4,4'-triphenylamine and iodine as an electrochromic material film.

The poly-4,4'-triphenylamine used was obtained by polymerizing 4,4' dichlorotriphenylamine using a Grignard reaction. The molecular weight was 2000 to 3000 in terms of polystyrene by GPC method.

Poly 4,4'-triphenylamine was dissolved in chloroform and spin coated on a glass substrate with a transparent electrode to obtain a poly 4,4'-triphenylamine thin film with a thickness of 400 Å. This thin film was heated to 10 ^-5 mmHg.
The mixture was sealed in a glass container with iodine under a high vacuum (Torr) and exposed to iodine saturated vapor for 2 hours at room temperature and 100°C to react with iodine.

After the reaction, the thin film was taken out and washed with ethanol to remove iodine, thereby obtaining a thin film of poly4,4'-triphenylamine/iodine reactant on a glass substrate with a transparent electrode.

This thin film is poorly soluble in chloroform, and the amount dissolved after being immersed in chloroform for a day and night is about 10% when reacted at room temperature and about 5% when reacted at 100°C. No increase in the amount of dissolution was observed even after immersion.

This confirmed that 4,4'-triphenylamine reacted with iodine and changed into something poorly soluble in chloroform.

Next, in order to confirm the redox reaction of the thin film reacted at 100°C, cyclic voltammetry measurements were performed, and the results are shown in Figure 1. The measurement was carried out using mol/lithium perchlorate and propylene carbonate solution as the electrolyte solution, and a platinum wire as the counter electrode.
Using a silver/silver chloride electrode as a reference electrode, the sweep speed was
It was performed at 10 mV/sec.

As a result, electrochromic properties were observed, with redox current peaks at two locations around +1.0V and +0.95V (vsAg/AgCl), and the color changing from transparent to brown to dark blue. In addition, the amount of electricity after 300 sweeps was 83% of the initial amount, and although the amount of electricity decreased, sufficient electrochromic properties were maintained.

Example 2 An electrochromic display element similar to Example 1 was produced. In this case, a poly-4,4'-triphenylamine thin film was prepared in the same manner as in Example 1,
It was sealed together with iodine in N ₂ gas, reacted for 2 hours at room temperature, degassed, and washed with ethanol.

This thin film was hardly soluble in chloroform, and the amount eluted after being immersed for one day and night was about 15%.

When cyclic voltammetry of this thin film was measured using the same method, similar electrochromic properties were confirmed. Also, voltage 0 to 1.2V (vsAg/
AgCl), and the amount of electricity after 150 sweeps is:
From Figure 2, which shows the changes in the number of oxidation-reductions and the amount of electricity reduced when oxidation-reduction is repeated, the initial amount was 86% (the amount of electricity at the first time was taken as 100%), but even at that time, there was sufficient electrolysis. It retained its chromic character.

Comparative Example 1 A 4,4'-triphenylamine thin film was prepared in the same manner as in Example 1, but cyclic voltammetry was measured as it was without reacting with iodine. As a result, as shown by the broken line in Fig. 2, similar electrochromic properties are initially exhibited, but
The thin film gradually dissolved into the electrolyte and no longer showed electrochromic properties after about 30 sweeps.

Example 3 An electrochromic display element was prepared using the reaction product of poly4,4'-(4''methyl)triphenylamine and iodine as an electrochromic film in the same manner as in Example 1.

Poly4,4'-(4''methyl)triphenylamine was obtained by polymerizing (4,4'dichloro)(4''methyl)triphenylamine using a Grignard reaction. The molecular weight was 2000 to 3000 in terms of polyethylene by GPC method.

This poly-4,4'(4" methyl) triphenylamine was dissolved in chloroform and spin-coated on a glass substrate with a transparent electrode in the same manner as in Example 1. A 4″ methyl)triphenylamine thin film was obtained. 10 ^-5 Torr
sealed in a glass container with iodine under vacuum,
It was exposed to iodine saturated steam at 100°C for 2 hours to react with iodine. After the reaction, the thin film was taken out and washed with ethanol to remove iodine, thereby obtaining a thin film of the poly-4,4'(4'' methyl) triphenylamine-iodine reactant on a glass substrate with a transparent electrode.

This thin film is poorly soluble in chloroform, and the amount dissolved after being immersed in chloroform for a day and night is approximately 14%.
Even after further immersion in chloroform, there was almost no increase in the amount dissolved. From this, it was confirmed that poly-4,4'(4''methyl)triphenylamine reacted with iodine and changed into something poorly soluble in chloroform.

In order to confirm the oxidation/reduction reaction of the above thin film,
Cyclic voltammetry measurements were performed using the measurement method described in Example 1, and the results are shown in FIG.

As a result, electrochromic properties were observed, with oxidation and reduction current peaks at three locations near +0.98V and +0.93V (vsAg/AgCl), and the color changing from transparent to dark blue.

In addition, when this measurement is repeated 300 times, the amount of electricity is 75% of the initial amount, as shown in Figure 4, which shows the relationship between the number of oxidation/reduction times and the amount of reduced electricity, which is similar to Figure 2, and the amount of electricity is decreasing. However, it retained sufficient electrochromic properties.

Comparative Example 2 Poly 4,4'(4'' methyl) was prepared in the same manner as in Example 3.
A triphenylamine thin film was prepared, but cyclic voltammetry was measured without reacting it with iodine. As a result, as shown by the broken line in Fig. 4, the same electrochromic properties are initially exhibited, but the thin film gradually dissolves into the electrolyte.
After about 15 sweeps, it no longer showed electrochromic properties.

Example 4 An electrochromic display element was prepared in the same manner as in Example 1 using a reaction product of poly4,4'-(4''methoxy)triphenylamine and iodine as an electrochromic material.

Poly4,4'-(4''methoxy)triphenylamine was obtained by polymerizing (4,4'dichloro)(4''methoxy)triphenylamine using a Grignard reaction. The molecular weight was 200 to 3000 in terms of polystyrene by GPC method.

This poly 4,4'(4'' methoxy)triphenylamine was dissolved in chloroform and spin-coated onto a glass substrate with a transparent electrode in the same manner as in Example 1. A thin film of triphenylamine (methoxy) was obtained. This thin film
It was sealed in a glass container with iodine under a vacuum of 10 ^-5 Torr, and exposed to iodine saturated steam at 100℃ for 2 hours.
Reacted with iodine. After the reaction, the thin film was taken out, washed with ethanol to remove iodine, and placed on a glass substrate with a transparent electrode (poly 4,4' (4″ methoxy)).
A thin film of triphenylamine-iodine reactant was obtained.

This thin film is poorly soluble in chloroform, and the amount dissolved after being immersed in chloroform for one day and night is approximately 20%.
Even after further immersion in chloroform, there was almost no increase in the amount dissolved. From this,
It was confirmed that poly-4,4'(4''methoxy)triphenylamine reacted with iodine and changed into something poorly soluble in chloroform.

In order to confirm the oxidation/reduction reaction of the above thin film,
Cyclic voltammetry measurements were performed using the measurement method described in Example 1, and the results are shown in FIG.

As a result, electrochromic properties were observed with oxidation/reduction current peaks near +0.95V and +0.78V (vsAg/agCl), and the color changed from transparent to brown to dark blue.

In addition, the amount of electricity when the sweep is repeated 300 times in this measurement is 52% of the initial value, as shown in Figure 6, which shows the relationship between the number of oxidation/reduction times and the amount of reduced electricity, similar to Figure 2, and the amount of electricity is 52% of the initial value. However, sufficient electrochromic properties were retained.

Comparative Example 3 A poly 4,4'(4'' methoxy) triphenylamine thin film was prepared in the same manner as in Example 4, but cyclic voltammetry was measured as it was without reacting it with iodine. As shown by the broken line in Figure 6, the same electrochromic properties were initially exhibited, but the thin film gradually began to dissolve into the electrolyte, and electrochromic properties were no longer exhibited after about 10 sweeps.

(Effects of the Invention) As explained above, the electrochromic display element of the present invention uses poly4,4'-triphenylamine, poly4,4'(4''methyl)triphenyl as an electrochromic film. By using a reaction product of an amine or poly-4,4'(4''methoxy)triphenylamine with an oxidizing agent, stable and uniform electrochromic thin films can be easily prepared even over large areas and are easily obtained. The resulting thin film is unlikely to be eluted into the electrolyte in a colored state and has extremely high durability.

[Brief explanation of drawings]

Figure 1 is a curve diagram showing the results of cyclic voltammetry measurements of poly-4,4'-triphenylamine and iodine reactants. - A curve diagram showing the relationship between the number of redox and the amount of electricity reduced when redox is repeated in a triphenylamine-iodine reaction product. Figure 3 shows the poly-4,4' (4″ methyl) triphenylamine-iodine reaction. Figure 4 is a curve diagram similar to Figure 1 for poly 4,4'(4'' methyl) triphenylamine-iodine reactant and poly 4,4'-
The second in (4″methoxy)triphenylamine
A curve diagram similar to that shown in Fig.
Figure 6 is a curve similar to Figure 2 for poly-4,4'(4''methoxy)triphenylamine-iodine reactant and poly4,4'(4''methoxy)triphenylamine. It is a diagram.

Claims (1)

[Claims] 1. In an electrochromic display element consisting of a display electrode made of an electrochromic material film provided on a pair of transparent electrodes and a counter electrode facing each other with an electrolyte interposed therebetween, the electrochromic material film is made of poly 4,4 An electrolytic device characterized by using a reaction product of '-triphenylamine, poly4,4'(4''methyl)triphenylamine or poly4,4'(4''methoxy)triphenylamine and an oxidizing agent. Chromic display element.