JPH089659B2 - Polymer and organic semiconductor material composed of the polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polymer serving as an organic semiconductor, which can be applied to electrochromic materials, electromagnetic shield materials, electrode materials and the like. More specifically, the present invention relates to a novel polymer capable of being doped and dedoped with electrolyte ions by an electrochemical method.

[Prior art]

In recent years, electronic materials have been actively researched, and among them, functional polymer materials using conjugated polymer materials have been attracting attention as having various possibilities.

It is known that a conjugated polymer usually forms a complex when doped with an impurity and has an electric conductivity from an insulating or semiconductor to a metal-like electric conductivity, and its conduction mechanism has not been clarified yet. , And is expected to be a functional material, and various materials have been studied.

Organic semiconductors that have been studied in the past include thiophene-based, pyrrole-based, and acetylene-based (JP-A-56-136469, Journal of Polymer Science, Polymer Chemical Ed.
ition, Volume 12, pages 11 to 20), etc., but polyacetylene is susceptible to oxygen and unstable in air, and polythiophene has the drawback that impurities that are dopants easily escape in air. .

〔Purpose〕

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polymer which exhibits an electric conductivity of a semiconductor region and can stably exist in air, and an organic semiconductor material comprising the polymer. To do.

〔Constitution〕

That is, according to the present invention, there is provided a polymer having a repeating unit represented by the following general formula (I).

(In the formula, m represents a degree of polymerization and represents an arbitrary number of 2 or more.) Further, according to the present invention, an organic semiconductor material comprising a polymer having a repeating unit represented by the following general formula (I) is provided. Provided.

(In the formula, m represents the degree of polymerization and represents an arbitrary number of 2 or more.) The polymer of the present invention has a property as a semiconductor by being doped with impurities during electrolytic polymerization. Examples of the impurities include anions taken in during electrolytic polymerization, and as typical examples thereof, tetrafluoroborate ion, perchlorate ion, hexafluorophosphate ion, hexafluoroarsenate ion, sulfate ion, hydrogen sulfate ion, Examples include trifluoroacetate ion and p-toluenesulfonate ion. In the polymer in which the anion is doped by electrolytic polymerization, the anion is separated from the polymer by applying a reverse voltage and becomes an insulating compound. This polymer can be made to have the property as a semiconductor again by bringing it into contact with an electron acceptor such as iodine, boron trifluoride, arsenic pentafluoride or antimony pentafluoride.

The polymer of the present invention has, for example, the formula The 1,2-dithienylethene monomer represented by and the supporting electrolyte are dissolved in a solvent to form a solution, and then a pair of electrodes is placed in this solution and a voltage is applied to deposit a polymer on the electrode surface. It can be manufactured by the so-called electrolytic gun method.

As the supporting electrolyte used in the electrolytic polymerization method tetramethylammonium perchlorate, tetraethylammonium perchlorate, tetrabutylammonium perchlorate, lithium perchlorate, tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate,
Tetrabutylammonium tetrafluoroborate, lithium tetrafluoroborate, tetramethylammonium hexafluoroarsenate, tetraethylammonium hexafluoroarsenate, hexafluoroarsenic tetrabutylammonium, sodium hexafluoroarsenate, tetramethylammonium hexafluorophosphate, hexafluorophosphoric acid Examples thereof include tetrabutylammonium, sodium hexafluorophosphate, sulfuric acid, tetramethylammonium hydrogen sulfate, tetrabutylammonium hydrogen sulfate, sodium trifluoroacetate, tetramethylammonium p-toluenesulfonate, and tetrabutylammonium p-trienesulfonate. It is preferable to use a polar solvent as the solvent used in the present invention, acetonitrile,
Benzonitrile, nitrobenzene, propylene carbonate, methylene chloride, tetrahydrofuran, dimethylformamide, dimethylsulfoxide and the like are used, and particularly preferably acetonitrile and methylene chloride are used. Also,
The electrode material used in the electrolytic polymerization method is a glass electrode (nesa glass) in which a metal oxide such as indium oxide or stannic oxide is deposited on the glass surface, a noble metal such as gold or platinum, or a carbon electrode such as glassy carbon. Can be used, but it is preferable to use Nesa glass.

As the electrolysis method, the reaction proceeds even if any one of the constant current electrolysis method, the constant potential electrolysis method, and the constant voltage electrolysis method is used, but 1,2-di (2,3'-thienyl) is used as a monomer. For electropolymerization when using ethene, a potentiostatic electrolysis method is preferable,
It is preferable to apply a potential of 0.8 V to 2.0 V, and more preferably 1.0 V to 1.3 V to the reference electrode SCE.

Polymerization in the case of using 1,2-di (2,2'-thienyl) ethene as a monomer proceeds even if any electrolytic method is used, but it does not grow as a film and grows powdery on the electrode. Go. The color of the polymer is black purple, and when a reverse current is applied, the anion as a dopant is desorbed to become a red polymer. On the other hand, a polymer of 1,2-di (2,3'-thienyl) ethene, for example, is obtained as a blue-green film, and then a reverse current is applied to remove the dopant from the film and cause a yellow heavy film. Change to coalesce.

Although the structure of each polymer produced by the method of the present invention cannot be determined unconditionally, all polymers show electric conductivity in the semiconductor region, are insoluble in organic solvents, and have excellent chemical stability. ing. For example, 1,2 as a monomer
When -di (2,2'-thienyl) ethene is used, it is considered that there are two α-positions in the thiophene skeleton and the polymerization proceeds from this position to give a linear one-dimensional polymer.
A similar α for 2'-di (2,3'-thienyl) ethene
3-position 1,2-di (3,3'-thienyl) ethene has 4 α-positions, and if the α-positions of these compounds react 3 or more positions, the polymer has a three-dimensional structure. It is believed that At present, it is preferable to use a polymer of 1,2-di (2,2'-thienyl) ethene, that is, a one-dimensional structure, considering the movement of the polaron, etc., which has been proposed in the electric conduction mechanism of the conductive polymer. Polymers of 1,2-di (2,3'-thienyl) ethene and 1,2-di (3,3'-thienyl) ethene are not preferable in this respect because the degree of freedom of the polymer chain is further reduced. Therefore, to obtain high conductivity, which is one of the characteristics required for electrode materials and electromagnetic shield materials,
A polymer structure of 1,2-di (2,2'-thienyl) ethene is preferred. In addition, since these polymers cause a color change in a state where impurities are doped and a state where they are undoped,
It can be used as an electrochromic material, and a monomer having different thiophene skeleton bonding positions can be used to produce a material that causes different color changes by polymerization.

[Effect]

According to the present invention, when the polymer grows in the form of a film, the film thickness can be controlled by the amount of energization, so that a secondary molding process is not required. Further, since the impurities are incorporated during the electrolytic polymerization, there is an advantage that the doping of the impurities, which is an important step for expressing the conductivity of the semiconductor region, can be performed substantially in one step.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these.

Example 1 144 mg (50 mmol /) tetrabutyl perchlorate of 1,2-di (2,2'-thienyl) ethene was placed in an electrolytic cell in which nickel was placed 1 cm apart from the ITO glass and the anode (2 cm ² ) with nickel as the cathode. Ammonium 520 mg (0.1 mmol /) methylene chloride 15 ml was added and dissolved, and then argon was blown in for 20 minutes and polymerized at a constant voltage of 2.7 V for 5 minutes to give a perchlorate ion-doped black-purple polymer. Are produced as fine powder on the anode. Next, when the direction of the electric current was reversed, the perchlorate ion was separated from the polymer, forming a red polymer. The weight after washing and drying is 0.
It was 3 mg.

Example 2 The same operation as in Example 1 was carried out except that acetonitrin was used instead of methylene chloride. When the polymerization is allowed to proceed for 30 minutes at a constant voltage of 5.5 V, a black powder polymer adheres to the anode. After washing this with acetonitrile,
It was dried, molded into a pellet at 200 kgf / cm ² , and the electric conductivity was measured and found to be 6.2 × 10 ^-2 Scm ^-1 .

Example 3 40 mg (10 mmol /) hexafluoroarsenic acid of 1,2-di (2,3'-thienyl) ethene was placed in an electrolytic cell equipped with ITO glass as an anode (2 cm ² ), nickel as a cathode, and SCE as a reference electrode. After adding and dissolving 360 mg (85 mmol /) of sodium and 20 ml of acetonitrile, argon was bubbled in for 20 minutes. 1.
When an electric charge of 250 mc was applied at a constant potential of 0 V vs SCE, a blue-green thin film polymer in which hexafluoroarsenic acid ions were doped on the anode was obtained. Next, when the direction of the electric current was reversed, the hexafluoroarsenic ion changed into a yellow polymer separated from the polymer.

Example 4 30 mg (10 mmol /) of 1,2-di (2,3′-thienyl) ethene and tetrabutyl perchlorate were placed in an electrolytic cell in which ITO glass was placed as an anode (2 cm ² ) and nickel was placed as a cathode at a distance of 1 cm. 590 mg (0.1 mmol /) of ammonium and 15 ml of acetonitrile were added and dissolved, and then argon was blown in for 20 minutes and the polymerization was allowed to proceed at a constant voltage of 3.0 V for 7 hours. It was obtained as a film when attached on the anode and peeled off from the electrode. This film-like material was stable in air and had an electric conductivity of 1.7 × 10 ^-4 Scm ^-1 .

Claims (2)

[Claims] 1. A polymer having a repeating unit represented by the following general formula (I). (In the formula, m represents the degree of polymerization and represents an arbitrary number of 2 or more.) 2. An organic semiconductor material comprising a polymer having a repeating unit represented by the following general formula (I). (In the formula, m represents the degree of polymerization and represents an arbitrary number of 2 or more.)