JPH0413718A - Electrochromic material - Google Patents

Abstract

PURPOSE:To obtain the title material capable of being made into a large area and readily processed into an arbitrary shape, having excellent oxidation- reduction stability and durability, containing a triphenylamine site, by subjecting a specific compound as a raw material monomer to electrolytic oxidation polymerization. CONSTITUTION:A compound shown by the formula (X is H, alkyl, alkoxy or halogen at ortho-, meta- or para-position), wherein a thiophene site is directly bonded to triphenylamine, as a raw material monomer is subjected to electrolytic oxidation polymerization preferably at 1.3-2.0V potential to give the objective material.

Description

Detailed Description of the Invention (Industrial Application Field) This invention is based on the following formula (where X is selected from a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom at ortho, meta, and para positions). The present invention relates to an electrochromic material produced by electrolytic oxidation polymerization of a raw material, in which a thiophene moiety is directly bonded to triphenylamine (representing a substituent).

(Prior Art) As a practical electrochromic thin film containing a triphenylamine structural unit, there is a poly(4,4'-triphenylamine) thin film already proposed by the present applicant (Japanese Patent Application Laid-Open No. 1983-1999). 28524). The thin film is prepared as follows. Such a polymer is dissolved in a solvent such as chloroform, and a film is formed on a transparent conductive glass such as ITO (indium-doped tin oxide) by a spin-coding method, and then heated to dope iodine and crosslink to make it insoluble and form an electrochromic (EC) film. )m film. The electrochromic thin film prepared in this way has excellent redox stability and
It has excellent durability and, as mentioned above, good moldability, making it extremely practical.

(Problems to be Solved by the Invention) However, the poly(4,4'triphenylamine)TiI film proposed by the present applicant has difficulty in producing a uniform ECff film when configuring a large-area EC element. Moreover, when constructing an EC element that includes a complicated pattern such as letters, there is a problem in that there is no simple and suitable processing method that can accurately remove unnecessary portions after film formation.

(Means for Solving the Problems) This invention focuses on these conventional problems, and as is well known, the advantages of electrolytic polymerization film forming method are that it is easy to form large areas and complex shapes. The EC thin film containing the triphenylamine structural unit was created with the following formula (in the formula, The above-mentioned problems are solved by producing the compound by electrolytic oxidation polymerization of a raw material monomer in which a thiophene moiety is directly bonded to triphenylamine represented by (indicates a substituent selected from among).

Generally, the conditions for electrolytic oxidative polymerization are constant current or constant voltage. In the case of the present invention, it is a necessary condition that oxidation occurs at the potential applied to the second wave in the portamogram. The potential at which electrolytic oxidative polymerization occurs is 1.3v to 2.
．． It is about 0M, and if it is too high, it will lead to inactivation of the membrane.

A series of results for polythiophenes (e.g. G, To
urillon in T, A, Skothe
im, (Ed), Handbook of Conduc
ting Poly+ners, vol, 1. Dekk
er, New York, 1986. p, 293.
), it is well known that when thiophene is oxidized, the protons on the carbons next to sulfur in the thiophene skeleton (2nd and 5th positions of thiophene) are removed, and the carbons of the same type bond together to form a polymer. . Therefore, in the present invention, 5
It is thought that a polymer having a structure represented by the following formula (in the formula, X represents the same as above) is produced by bonding at a positional position. The results of FT-JR (Fourier transform infrared spectroscopy) shown later do not contradict this. Therefore, since the pi-electron network continues on the polymer, it is expected to exhibit considerably high conductivity, and even when used as an ECfli film, it can be expected to have good responsiveness. In addition, when an EC device is constructed, the oxidation process of the triphenylamine moiety, which is extremely stable unlike polythiophenes, can be distinguished, making it easy to consider the potential that can be used stably, and it is thought to have many advantages in addition to film-forming properties. .

(Examples) The present invention will be specifically explained below using Examples and Comparative Examples.

, Comparison 1 day - Direct electrolytic polymerization of triphenylamine.

Yoshino et al. have shown that conductive polymer thin films can be produced by electrolytic oxidative polymerization of condensed hydrocarbons such as benzene [J, Elketroanal, Chew,
.

195 (1985) 203. and J. CheIll.
, Soc, Che+n, Comn+um,, (
1986) 550. ), electrolytic oxidative polymerization of triphenylamine was attempted using this method as follows.

The electrolyte is 0.3M) liphenylamine, 0.1MCu
C1g, 0. Electrolysis was carried out using a nitrobenzene solution of I M LiAsF, using Nesa glass as the working electrode and a platinum wire as the counter electrode, keeping the working electrode at 10 V with respect to the counter electrode. When benzene was added instead of triphenylamine, a black film was formed, but in this case, the solution turned reddish brown, but a thin film could not be formed on Nesaglass no matter how much electrolysis was carried out. This is probably because unsubstituted triphenylamine is oxidized and becomes a dimer immediately, but the cation of the dimer of triphenylamine is stable, and the cation is also stable to a certain extent, so electrolytic polymerization does not proceed any further. It is considered that this is not possible.

1"1- Electropolymerization in benzonitrile.

The raw material monomer is a new compound, and for this purpose, the literature [Makromol, Chem, vol. 189,
1755, 1988] was synthesized as follows. 4. In a 300yd 30 round bottom flask.
Add 0 g (0,167 mol) of metallic magnesium for Grignard reagent, insert a magnetic rotor, and after vacuum degassing, add about 1 mol of diethyl ether dehydrated using metallic sodium.
Add 10 d of vacuum distillation and add 25 g (0,153
A Grignard reagent was prepared by dropping mol) of 2-bromothiophene. In a separate 3001d 30 round bottom flask were added 5 g (0,015 mol) of 4,4' dichlorotriphenylamine (synthesized from aniline and p-iodochlorobenzene by a type of Ullmann reaction) and a catalyst amount (0
, 087 g) of dichloro(1,3-(diphenylphosphino)propane)nickel(II) was added, a magnetic rotor was placed, and after vacuum degassing, about 100 m of dry diethyl ether was added by vacuum distillation, and the ice After cooling in a bath, add about 90 d of the Grignard reagent solution under nitrogen,
Synthesis was performed by refluxing on an oil bath for 3 days.

After the reaction was completed, cool it in an ice bath, and add about 70IIi of 2 mol/liter aqueous hydrochloric acid solution while checking the condition.
Extracted with diethyl ether. The orange ether phase was washed with saturated aqueous sodium carbonate, dried over calcium chloride overnight, filtered and evaporated, and vacuumed with a rotary pump to remove the by-product thiophene. did. The crude product was separated and purified by column chromatography (silica gel/benzene:hexane (volume ratio 1:4)) and further recrystallized from ethanol to obtain the desired raw material monomer of formula 1 where X is a hydrogen atom. Ta. The color of the raw material monomer was very pale yellow. The melting point was 182°C. FT-I R shown later
There were no contradictions in the results. The results of elemental analysis were as follows, and it was confirmed to be the target substance.

Theoretical values: carbon 76.3%, hydrogen 4.60%, nitrogen 3.4
0%, sulfur 15.7% Experimental values: carbon 76.6%, hydrogen 4.65%, nitrogen 3.3
5%, sulfur 15.9% Electrolytic polymerization of the obtained sulfur was carried out under the following conditions.

As a solvent, benzonitrile that was vacuum distilled after dehydration with calcium hydride was used, as a supporting electrolyte 0.1 mol/liter normal tetrabutylammonium hexafluorophosphate was used, and as a reference electrode propylene carbonate was used. The silver/silver chloride electrode inside was separated by two glass filters. The concentration of the raw material monomer was 5 mmol/liter. I on the working electrode
TO glass (surface resistance 10 ohms/mouth) was used.

A platinum wire was used as the counter electrode. Electrolytic polymerization was carried out in a glove box with a dry nitrogen atmosphere using a three-compartment electrolytic cell.

An ITO electrode was placed in the central chamber of the cell, a counter electrode was placed in one chamber separated by a glass filter, and a reference electrode was placed in the other chamber separated by a glass filter. Electrolysis is 10, 5v and 2. The rectangular wave was repeated at intervals of 1 second between OvO for a total of 1 to 3 minutes. The resulting insoluble thin film was yellow in color. Similar thin films were also obtained by repeated potential sweeps ranging from Ov to 1.9V.

The FT-IR spectrum of the obtained thin film is shown in Figure 1.
Figure 2 shows the spectrum of the raw material monomer. The spectrum of the electrolytically polymerized film was measured by scraping off the film on ITO using the KBr method. 1270° 1310, 1480.15 specific to the triphenylamine moiety in both monomer and polymer
Strong absorption near 90 cm-' is observed, indicating that a triphenylamine moiety is included. In polymers,
790C characteristically found in 2.5-disubstituted thiophenes
The structure of the polymer shown in Formula 2 is also supported because the absorption of 1-' increases and the absorption of 690C1m-', which is characteristic of 2-monosubstituted thiophene contained in the monomer, decreases.

The electrochromic properties of the resulting thin films were evaluated in propylene carbonate, a more practical solvent.

The cyclic portammogram of the polymer on ITO in a propylene carbonate solution containing 1.0 mol/liter lithium perchlorate is shown in FIG. The area of the thin film was approximately 0.5CI+1". Redox was repeated more than 100 times in the oxidation wave, but the waveform did not change and was very stable. Electrochemical cell for absorption spectrum measurement Figure 4 shows the changes in the visible to near-infrared absorption spectrum due to redox.The color of the thin film reversibly changed from yellow to black when oxidized at the second wave.

Implementation 1- Electropolymerization in mixed solvents.

In Example 1, the solvent for producing the electropolymerized membrane was changed from benzonitrile to acetonitrile and benzonitrile (volume ratio 2).
:1) Electrolytic polymerization was carried out in the same manner as in Example 1, except that a mixed solvent was used and the concentration of the sample was changed to 4 mmol/liter, and a yellow thin film was obtained as in Example 1. The portammogram using a platinum wire working electrode is shown in FIG. This sample seemed to have a somewhat sharper peak compared to Example 1, but similarly showed stable EC characteristics. From the cyclic voltammetry of the electrolytic polymerization solution, it appeared that the electrical efficiency of the electrolytic polymerization was somewhat improved compared to Example 1.

The solvent and supporting electrolyte used in the electropolymerization used in this invention are not limited to nitrile solvents and n-tetrabutylammonium hexafluorophosphate, but can be ordinary non-aqueous solutions as long as they are not oxidized and decomposed at the electropolymerization potential. Solvents and electrolytes used in electrochemistry can be used. Similarly, the driving solvent for the produced electrochromic thin film is not limited to a propylene carbonate solution of lithium perchlorate.

(Effects of the Invention) As explained above, according to the present invention, it contains a triphenylamine moiety, has good redox stability, is excellent in durability, and can be made into a large area.1. Moreover, it is possible to easily obtain an ECI membrane that can be formed into any desired shape.

[Brief explanation of drawings]

Figure 1 shows the FT-
JR spectrum diagram, Figure 2 is an FT-IR spectrum diagram of the raw material monomer, Figure 3 is a cyclic portamogram diagram of the electrolytically polymerized membrane obtained in Example 1, and Figure 4 is the electrolytically polymerized membrane described above. A diagram showing changes in the absorption spectrum due to oxidation of the membrane. FIG. 5 is a cyclic portammogram diagram of the electrolytically polymerized membrane obtained in Example 2.

Claims (1)

[Claims] 1. The following formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) (X in the formula is a hydrogen atom, or an alkyl group at the ortho, meta, or para position, an alkoxy group, 1. An electrochromic material produced by electrolytic oxidative polymerization using a compound represented by (indicates a substituent selected from halogen atoms) as a raw material monomer.