JPH0730315B2 - Electrochromic display device and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrochromic (EC) display device in which an EC film on the surface of a display electrode is formed by an electrolytic oxidation polymerization reaction of anilinonaphthalene and its derivative. The present invention relates to an EC display material made of a polymer and a method for producing the same.

(Technical background of the invention) The thin film synthesis method by electrolytic polymerization reaction has recently been particularly expected and attracted attention as an organic thin film synthesis method having a new function as shown by an electrolytic poly (pyrrole) film showing high electric conductivity. There is. The electrolytic polymerization method does not require a polymerization initiator because the polymerization reaction is carried out by controlling the potential and current value, and this method is not limited to electrolytic solution conditions, electrode materials, electrolysis time,
By changing the electrolysis potential and electrolysis current, it is possible to easily control the film formation process, such as changing the physical properties of the film and regulating the film thickness. The thin film produced by the electrolytic polymerization method is (1) the film is uniform, (2)
The film has properties such as strong adsorption to the electrode surface and (3) reproducibility in the structure and composition of the film. In this method, a thin film is formed on the surface of the electrode as the electrolytic polymerization reaction progresses. Therefore, it is possible to produce a composite electrode material in which the electrode and the thin film are integrated. It can be expected to be applied to electrochemical sensors, ion-selective electrodes, electrochromic display (ECD) materials, electrode catalyst materials that can be used in fuel cells, and organic battery materials. Also,
The produced thin film can also be peeled from the electrode, and this electrolytic polymerization method uses a polymer complex film that has a catalytic action on a substrate or a film that has different electrical properties from the conventional polymer synthetic film in a homogeneous system. It will be an effective means for developing thin film synthesis with new functions.

Among the typical conventional EC materials, the EC film produced by utilizing electrolytic oxidation polymerization is poly (pyrrole), poly (thiophene),
There are poly (aniline) films, etc., and these films show EC characteristics by a redox reaction. For example, a poly (aniline) film on a transparent electrode undergoes redox reaction in the potential range of 0 V to 0.3 V (vs. saturated calomel electrode) in an acidic aqueous solution, and changes to yellow-green (Journal of Electroanalytical Chemistry, Vol. 161). Page 419, 1984, Journal of
Electroanalytical Chemistry, 161 , 419 (1984)). In addition, the poly (thiophene) film is
Redox blue color changes in the potential range of ~ 1.0 V (vs. saturated calomel electrode) and changes to red-blue (Journal of Electroanalytical Chemistry, 148, 299 pages, 1983, Journal of Electroanalytical Chemistry, 1
48, 299 (1983)). Thus, among the polymer films prepared by electrolytic oxidation polymerization, polymer films showing good EC characteristics accompanying the redox reaction of the film itself are not well known, and their development has been sought. There is.

(Object of the Invention) An object of the present invention is to provide an EC display material comprising a novel redox polymer film easily prepared by electrolytic oxidation polymerization of anilinonaphthalene and its derivative exhibiting EC characteristics, and a method for producing the same. It is in.

(Structure of Invention) The EC display device of the present invention is a novel redox polymer film represented by the following general formula, which is deposited on a transparent electrode.

Wherein R is H, SO ₃ H, SO ₃ NH ₄ , SO ₃ Na or SO ₃ K, n
Is in the range of 10 to 500.

The polymerization monomer used to prepare this redox polymer film is represented by the following general formula.

(In the formula, R is H, SO ₃ H, SO ₃ NH ₄ , SO ₃ Na or SO ₃ K.) By dissolving these polymerization monomers in a suitable supporting electrolyte solution and electrolytically oxidizing them, A redox polymer film showing EC characteristics is obtained on the surface of a display electrode.

The electrolytic oxidative polymerization can be carried out using a normal two-electrode type cell, but it is more preferable to use a three-electrode type cell provided with a working electrode, a counter electrode and a reference electrode. The electrolytic solution used for the electrolytic oxidative polymerization of the monomer for polymerization is preferably an acidic aqueous solution, and when the monomer is poorly soluble in water, an acidic solution prepared by adding an organic solvent such as methanol, ethanol or dimethylsulfoxide so that the monomer can be easily dissolved It is preferable to use an aqueous solution. When the prepared transparent electrode coated with a polymer film is transferred to a supporting electrolyte solution and a voltage is applied thereto, the color of the polymer film can be changed due to the redox reaction of the polymer film.

(Effect of the invention) According to the present invention, a novel redox polymer film showing excellent EC characteristics on a transparent display electrode can be easily obtained by electrolytically oxidatively polymerizing the above-mentioned polymerization monomer in a supporting electrolyte solution. It is obtained and can be used as an EC display material.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The invention is not limited to these examples only.

Example 1 An electrolytically oxidized polymer film-coated electrode of ammonium 8-anilino-1-naphthalenesulfonate (hereinafter abbreviated as ANSA) was prepared as follows. SnO ₂ −In ₂ O ₃ on the glass substrate
A normal three-electrode type H using a transparent electrode (electrode area is 1 cm ² ) with a thin film deposited as a working electrode, a platinum winding as a counter electrode, and a saturated sodium chloride calomel electrode (hereinafter abbreviated as SSCE) as a reference electrode. A type cell was used. An electrolytic solution having the following composition was used for electrolytic oxidation polymerization of ANSA.

Composition of Electrolyte Solution: ANSA: 20 mM HClO ₄ : 0.1M NaClO ₄ : 0.2M Solvent: H ₂ O Before electrolysis, nitrogen was sufficiently aerated in the electrolyte solution to remove oxygen in the solution. Immerse the transparent electrode in the electrolyte, 0.4V ~ 1.2V
The potential range (relative to SSCE) was potential scanned at a scanning rate of 100 mV / S. The current-potential curve obtained at this time is shown in FIG.
Shown in. From this figure, it can be seen that ANSA is electrolytically oxidized at a potential near 0.6 V (vs SSCE). At the same time, it was observed that the surface of the transparent electrode was covered with a dark purple film and the color of this winding gradually increased. When the potential was scanned toward the negative potential side, the color of the film changed to transparent yellow with the reduction. Therefore, it is considered that this reduction wave is not due to the reduction of the oxidation product of the ANSA monomer, but due to the reduction of the ANSA polymer film itself formed on the transparent electrode. That is, ANSA is
It can be seen that it is irreversibly oxidized near 0.6 V (vs SSCE) to give an ANSA polymer film on the transparent electrode surface. Therefore, at the potential at which ANSA electrolytic oxidation polymerization occurs sufficiently, at 1.0 V (vs SSCE), 75
Constant-potential electrolysis was performed for 2 seconds to prepare an ANSA polymer film-coated transparent electrode. The total amount of electricity consumed for electrolytic oxidation polymerization was 64 mC / cm ² . After thoroughly washing this electrode with distilled water, the electrode was transferred to an acidic aqueous solution containing 0.2 M perchloric acid and 0.2 M sodium perchlorate as a supporting salt, and the potential was scanned to find the current-potential shown in FIG. 1 (B). A curve was obtained. As can be seen from FIG. 1 (B), the redox reaction of the ANSA polymer film was reversible, and it was confirmed that the oxidation reaction changed the color from yellow to dark purple, and the reduction reaction changed the color from dark purple to yellow. .

The visible light absorption spectrum of the ANSA polymer film was measured by a spectrophotometer, and the spectra of the oxidant and the reductant of the polymer film were as shown in (a) and (b) of FIG. 2, respectively. .

Next, the molecular weight of the ANSA polymer was measured by GPC. As a result, the weight average molecular weight was 2.5 × 10 ⁴ (polystyrene equivalent).
And the molecular weight distribution (MW / MN) was 1.31. Therefore, it can be seen that the ANSA polymer is composed of a polymer in which about 80 monomers are bonded on average.

Next, the production of the polymer film will be examined. Fig. 1 (B)
As can be seen from the current-potential curve shown in Fig.
The redox waves observed in the 1.2 V (VS.SSCE) potential region are a pair of waves, respectively, which indicates that the electrode active species contained in the polymer film is a single species. ing. The ANSA monomer polymerization reaction proceeds by the radical cation of the electrolytically oxidized monomer or the coupling reaction between the cations, but since this radical cation or cation is localized at the amino group, electrolysis containing electrode active species is carried out. As the structure of the oxidation product, the formula 2 (a)-
A polymer unit as shown in (d) can be considered. This was investigated by nuclear magnetic resonance spectroscopy to reveal the structure of the polymer. ANSA Monomer and Polymer ¹ H
-NMR spectra are shown in Fig. 3 (A) and (B), respectively. D-Dimethylformamide was used as the solvent. For convenience, Formula 3 shows the structure of the ANSA monomer, and the numbers in Formula 3 distinguish hydrogen atoms in the molecule. This number is the third
It is attached in the diagrams of FIGS. (A) and (B), and the attribution of each signal is clearly shown. ¹ H-NMR spectrum of monomer (3rd
In the figure (A)), the signal at 6.70 to 6.74 ppm is assigned to the 10th hydrogen atom of the monomer. This signal remains as it is after the polymerization (FIG. 3 (B)), which shows that the benzene ring of the anilino group does not participate in the reaction.
Comparing the spectra of both the ANSA monomer and the polymer, it can be seen that the signal at 7.49 to 7.52 ppm in FIG. 3 (A) is not observed in FIG. 3 (B). This signal is assigned to the 4th hydrogen atom of the naphthalene ring,
It is considered that the polymerization reaction is proceeding at this position. From this result, the structure of the polymer is represented by the formula (2) (a), and it can be considered that the electrode active site of this polymer corresponds to a diamine = diimine type redox couple.

Formula 2 Example 2 N-phenyl-α-naphthylamine (hereinafter abbreviated as PN) was oxidized in an electrolytic solution having the following composition to obtain an EC film on a transparent electrode.

Electrolyte composition: PN: 5mM HClO ₄ : 0.1M NaClO ₄ : 0.2M solvent: water + methanol (volume ratio is 3:
7) A current-potential curve obtained by electrolytically oxidatively polymerizing PN in the above electrolytic solution in accordance with the procedure shown in Example 1 is shown in FIG. 4 (A). Similar to ANSA of Example 1, PN irreversibly oxidatively polymerizes at a potential of 0.8 V (vs SSCE) to give a polymer film on a transparent electrode.

Sufficient potential, 1.0 V (vs.
Electrostatic potential electrolysis for 75 seconds in SSCE) to prepare a PN polymer film coated electrode. The total amount of electricity consumed for electrolytic oxidation polymerization is 45
It was mC / cm ² . The current-potential curve showing the redox reaction of the EC film obtained by transferring the prepared EC film-coated electrode to an acidic aqueous solution containing 1 M HClO ₄ is shown in FIG. 4 (B). The EC film undergoes a reversible redox reaction, and the oxidation reaction causes a pale yellow to blue,
It was confirmed that the color changed from blue to pale yellow due to the reduction reaction. The visible light absorption spectrum of this EC film is shown in FIG. (A) and (b) in FIG. 5 are spectra of the oxidant and the reductant of the EC film, respectively.

Next, according to Example 1, the structure of the PN polymer film was examined by nuclear magnetic resonance spectroscopy. ¹ H-NM of PN monomer and its polymer
The R spectrum is shown in FIGS. 6 (A) and 6 (B). D-Chloroform was used as the solvent. The numbers in FIG. 6 represent hydrogen atoms in the AN monomer molecule shown in Formula 5. The difference between the spectra in FIGS. 6 (A) and 6 (B) is the difference in Example 1.
It can be interpreted similarly to the difference in the NMR spectra of the ANSA monomer and its polymer. Therefore, PN polymer is ANSA
It can be considered to have a structure similar to a polymer.

Comparative example Using 7-anilino-1-naphthol-3-sulphonic acid and 7-anilino-4-naphthol-2-sulphonic acid, represented by formulas 6 and 7, according to the procedure given in Example 1, these compounds The formation of the electropolymerized film and the EC characteristics were investigated. Both of these compounds give a polymerized film on the transparent electrode surface by electrolytic oxidative polymerization. However,
The electrochemical activity of these polymer films was much smaller than that of ANSA or PN polymer films, and no clear color change was observed with the redox reaction of the polymer films.

[Brief description of drawings]

FIG. 1 (A) shows a current-potential curve when the polymerization monomer ANSA undergoes electrolytic oxidative polymerization. Figure 1 (B) shows the prepared AN
The SA polymer film-coated electrode is immersed in a supporting electrolyte solution and subjected to potential scanning to show a current-potential curve showing the redox reaction of the ANSA polymer film. Figure 2 shows the visible light absorption spectrum of the ANSA polymer film.
(A) and (b) therein show visible light absorption spectra of the oxidant and the reductant of the ANSA polymer film, respectively. FIGS. 3A and 3B are ¹ H-NMR spectra of ANSA monomer and ANSA polymer, respectively. FIG. 4 (A) shows a current-potential curve when the polymerization monomer PN undergoes electrolytic oxidative polymerization. FIG. 4 (B) shows the current-potential curve showing the redox reaction of the PN polymer film obtained by immersing the prepared PN polymer film-coated electrode in a supporting electrolyte solution and scanning the potential. FIG. 5 is a visible light absorption spectrum of the PN polymer film, in which (a) and (b) show the visible light absorption spectra of the oxidized form and the reduced form of the PN polymer film, respectively. FIGS. 6 (A) and (B) show ¹ H-of PN monomer and PN polymer.
It is an NMR spectrum.

Claims (4)

[Claims] 1. An electrochromic display device characterized in that the electrochromic device deposited on the transparent electrode is a redox polymer film represented by the following general formula: Wherein R is H, SO ₃ H, SO ₃ NH ₄ , SO ₃ Na or SO ₃ K, n
Is in the range of 10 to 500. 2. A polymerization monomer represented by the following general formula: (Wherein R is H, SO ₃ H, SO ₃ NH ₄ , SO ₃ Na or SO ₃ K) is electro-oxidatively polymerized in a supporting electrolyte solution to give electro-mic characteristics on the display transparent electrode. A method for manufacturing an electrochromic display device, which comprises preparing the redox polymer film shown. 3. The production method according to claim 2, wherein the supporting electrolyte solution is an acidic aqueous solution. 4. The production method according to claim 2, wherein the supporting electrolyte solution is an acidic aqueous solution containing an organic solvent.