JPS6144921A - Organic semiconductor composition - Google Patents

Abstract

PURPOSE:The titled composition which is nontoxic and excellent in workability and can be obtained without any molding step, prepared by doping a specified polymer with anions. CONSTITUTION:The titled composition of an electric conductivity of 10<-2>-2S/cm is obtained by doping a thiophene polymer comprising repeating units of formula IIIor IV, obtained by electrolytically polymerizing a compound of formula I or IItogether with a supporting electrolyte (e.g., tetramethylammonium tetrafluoroborate) in a polar solvent (e.g., acetonitrile) in an inert atmosphere such as Ar with anions (e.g., tetrafluoroborate ion) supplied from the supporting electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an organic semiconductor composition comprising a novel thiophene polymer.

In recent years, various types of industrial equipment have become increasingly electronic, making it possible to make them smaller and improve their performance. The growth of industries such as semiconductors, integrated circuits, and LSI has contributed significantly to this background, and it is predicted that the scope of use of electronic materials will continue to expand and demand will continue to increase.

BACKGROUND OF THE INVENTION Under these circumstances, the development of new semiconductor materials has become an important issue, and research on organic semiconductors in addition to inorganic semiconductors is being actively conducted.

Among organic materials, polymer materials have excellent moldability, plasticity, and flexibility, and polymer semiconductors are expected to be particularly widely used. As a polymer semiconductor, boria heptyrene,
Polymers such as polyphenylene have been developed in which electron acceptors are added to give them semiconductor properties. For example, [Journal of the American Chemical Society (J, Am, Cbem, Soc.
) Volume 100, Page 1013 (1978)'!
Synthetic metal (5ynth, Met,
) Volume 1, Page 307 (1980)]. Also,
Polythiophenes in which the thiophene ring has no substituents are also known. For example, [Makromol.

Chem,) Volume 185, Page 1295 (1984
Year)〕.

Problems that the invention aims to solveHowever, unlike general-purpose thermoplastic polymers, many of the polymers used as conventional semiconductor materials do not melt even when heated, but remain in a solid state and thermally decompose. Therefore, polyacetylene has the disadvantage of poor moldability and processability, as well as low chemical and mechanical properties. Polyacetylene also has the disadvantage of being susceptible to the action of oxygen and being unstable in air. Neither of these can be said to be practical. Furthermore, many electron acceptors are highly toxic, and improvements have been desired.

Furthermore, the conductivity of a semiconductor made by doping polythiophene with anions decreases relatively rapidly in the air, which has been a problem in practical use.

The present inventors conducted extensive research to overcome the drawbacks of conventional polymer semiconductors, and as a result, discovered that a certain type of thiophene polymer was suitable for this purpose.Based on this knowledge, the present inventors developed the present invention. He came up with an invention.

A means for solving the problem, that is, the present invention provides an organic semiconductor composition in which an anion is doped into a polymer consisting of the formula or a repeating unit represented by the formula.

1 of the present invention, all of which are new substances that have not been described in literature, and which are electrically insulating as they are, include tetrafluoroborate ion, perchlorate ion, hexafluorophosphate ion, and hexafluoroarsenic. When doped with anions such as acid ions, sulfate ions, hydrogen sulfate ions, trifluoroacetate ions, and p-toluenesulfonate ions, it exhibits semiconductor properties.

The thiophene-based polymer of the present invention can be produced, for example, by electrolytically polymerizing the formula or a compound represented by the formula. The polymer obtained by electrolytic polymerization has a structure doped with anions in the supporting electrolyte used, and has semiconductor properties.

The electropolymerization is advantageously carried out in a polar solvent and under an inert atmosphere. In this case, polar solvents include acetonitrile, nitrobenzene, nitromethane, benzonitrile, propylene carbonate, tetrahydrofuran, methylene chloride, dimethylformamide, dimethyl sulfoxide, hexamethylphosphorotriamide, 1-methyl-2-pyrrolidinone, dimethyl sulfate, diethyl sulfate. etc. are preferable. Further, as the inert atmosphere, nitrogen, argon, etc. are used. By carrying out the reaction under an inert atmosphere in this manner, it is possible to prevent the reaction intermediate from combining with oxygen and producing by-products.

In addition to noble metals such as gold and platinum, glass electrodes in which indium oxide, stannic oxide, and the like are deposited on the glass surface are also used as electrode materials.

Supporting electrolytes include tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate, tetra-n-butylammonium tetrafluoroborate, lithium tetrafluoroborate, tetramethylammonium perchlorate, tetraethylammonium perchlorate, and tetrafluoroborate. Tetra-n-butylammonium chlorate, lithium perchlorate, tetramethylammonium hexafluorophosphate, tetra-n-7 hexafluorophosphate
'Tylammonium, sodium hexafluorophosphate, tetra-n-butylammonium hexafluoroarsenate, sodium hexafluoroarsenate, sulfuric acid, tetramethylammonium hydrogensulfate, tetra-n-butylammonium hydrogensulfate, sodium trifluoroacetate, p- )
Examples include tetramethylammonium luenesulfonate and tetra-n-butylammonium p-toluenesulfonate.

The compound (2) above is a new compound, for example, 3-bromo-
It is synthesized by reacting 2,2'-bithiophene with sodium methoxide. 3-Bromo-2,2'-bithiophene used in this case is a known compound. For example, 2,3-dibromothiophene is reacted with n-butyllithium, and 3,3'-dibromo-2,2' - It is synthesized by synthesizing bithiophene, then reacting it with metallic magnesium, and then hydrolyzing it [Acta, Chem, Scandinavica,
5cand,) Volume 15, Page 1393 (196
1st year), Ark for Chemi (Ark iv, K
em j) Volume 28, Page 99 (1967 Sleeve)].

Effects of the Invention The polymer of the present invention has an anion-doped structure obtained by electrolytic polymerization, and has the advantage that the polymerization and doping processes can be carried out substantially in one step. In addition, the shape of the polymer is formed as a film on the electrode surface, and the film thickness can be adjusted by the amount of electricity passed through the electrolytic cell, making it possible to omit the molding process. Further, the anions to be doped are supplied from a neutral supporting electrolyte, which is often stable in the air, improves workability, and is advantageous in terms of toxicity. The conductivity of the polymer is good, ranging from 10-2 S/cm to a maximum of about 2 S/cm, and this value does not decrease even in the air, making it possible to apply it to electrode materials, electromagnetic shielding materials, solar cells, etc.

Semiconductors made by doping the polymers shown in (I) and (II) with anions have the above-mentioned features, but when comparing the mechanical properties of the membranes, (Kawa's) is superior.

Example Next, the present invention will be explained in more detail with reference to Examples.

Reference Example 1 22.5 M of dehydrated methanol and 1.8 g (78 milligram atoms) of metallic sodium were placed in a 50-three-necked flask equipped with a reflux condenser, a stirrer, and a calcium chloride tube. After the violent reaction subsided, 25 mfI of potassium iodide (0,1
5 mmol), 3-bromo-2,2'-bithiophene 6
．． 9 g (28 mmol), cupric oxide 1.12 g (1
4 mmol) was added. The mixture was stirred at 100°C for 120 hours, and the reaction product was filtered off. The filtrate was poured into twice the volume of ice water and extracted with ether. After distilling off the ether, the residue was distilled under reduced pressure to obtain 1.1 g (20%) of 3-methoxy-2,2'-bithiophene as a colorless transparent liquid. Boiling point 123°C
(3mmHg).

Example 1 Two platinum plates (2X2=4crII) with an interval of 1 cm
3-methoxythiophene 0.22
8 (2 mmol), hexafluorophosphate tetra-n-
7" 0.194 g (0.5 mmol) of tylammonium, 10 Tnl of acetonate was added and dissolved. After blowing in argon for 15 minutes, electrolytic polymerization was carried out at 25°C. Current density was 2 rrA/ After polymerization for 2 hours at cJ, 22.8 m9 of a black film-like polymer doped with hexafluorophosphate ions on the anode was obtained, and its conductivity was 5.7 x 10'' 87 cm.

Even when this sample was left in the air for 8 days, the conductivity did not decrease.

Example 2 chicken.

In the electrolytic cell described in Example 1, 3-methoxy-2,2'
- bithiophene 0.098 g (0.5 mmol), tetrafluoroboric acid tetra-n-butylammonium 0
．． 165 g (0.5 mmol), nitrobenzene l
QmJ was added and dissolved. Thereafter, the same operation as in Example 1 was performed, and a black film-like polymer 37.6# doped with tetrafluoroborate ions was obtained, and its electrical conductivity was 2.4 S/cm. Even when this sample was left in the air for 8 days, the conductivity did not decrease.

Example 3 In Example 2, a glass electrode (2X
When the same operation was performed except that 2=4cJ) was used, a black film-like polymer doped with tetrafluoroborate ions 40.0+11f was obtained, and its electrical conductivity was 8.3xio-1S/cm. showed that.

Claims (1)

[Claims] 1. An organic semiconductor composition obtained by doping an anion into a polymer consisting of repeating units represented by the formula: thing. 2. A patent claim in which the anion is a tetrafluoroborate ion, perchlorate ion, hexafluorophosphate ion, hexafluoroarsenate ion, sulfate ion, hydrogen sulfate ion, trifluoroacetate ion or p-toluenesulfonate ion A composition according to scope 1.