WO2011102390A1 - Aromatic compound, organic thin film using same, and organic thin film element provided with said organic thin film - Google Patents

Abstract

Provided is an aromatic compound which exhibits excellent charge transporting properties, and which can be used as an organic semiconductor material exerting high stability. The aromatic compound is represented by formula (1). [Ar¹¹ represents a group containing an aromatic ring, and X¹¹ and X¹² represent a group represented by formula (1a) and (1b). In formula (1a) and (1b), Ar¹² and Ar¹³ represent an aromatic hydrocarbon group having 6 or more carbon atoms, R¹¹, R¹², R¹³, and R¹⁴ represent a hydrogen atom, a halogen atom, or a monovalent group, and X¹³, X¹⁴, X¹⁵, and X¹⁶ represent an oxygen atom, a sulfur atom, or a selenium atom.]

Description

Aromatic compound, organic thin film using the same, and organic thin film element including the organic thin film

The present invention relates to an aromatic compound, an organic thin film using the same, an organic thin film element including the organic thin film, an organic thin film transistor, and an organic photoelectric conversion element.

An organic thin film containing an organic semiconductor material having a charge (meaning electron or hole, hereinafter the same) transportability is expected to be applied to organic thin film elements such as organic thin film transistors, organic solar cells, and optical sensors. . In recent years, various organic p-type semiconductor materials (showing hole transport properties) and organic n-type semiconductor materials (showing electron transport properties) capable of forming a thin film have been studied.

As an organic p-type semiconductor material, a compound having a thiophene ring such as oligothiophene or polythiophene can take a stable radical cation state, and thus is expected to exhibit high hole transportability. In particular, oligothiophenes having a long chain length are expected to have higher hole transportability because the conjugation length becomes longer. For example, ethylenedioxythiophene (EDOT) -thienothiophene oligomer has been reported to have high conjugation properties (see Non-Patent Document 1).

As a result of investigations by the present inventors, when the compounds having various thiophene rings as described above are used as an organic semiconductor material for an organic thin film in an organic thin film element, a high charge transport property can surely be obtained. confirmed. However, when such an organic thin film element is used over a long period of time, the charge transport property tends to gradually decrease. Considering the practicality of the organic thin film element, it is desirable that the organic semiconductor material has a high charge transportability and a high stability so that such a high charge transportability can be maintained as long as possible. .

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an aromatic compound that can be applied as an organic semiconductor material having excellent charge transportability and high stability. . Another object of the present invention is to provide an organic thin film obtained by using such an aromatic compound, and an organic thin film element provided with the organic thin film, particularly an organic thin film transistor and an organic photoelectric conversion element.

In order to achieve the above object, the aromatic compound of the present invention is represented by the formula (1).

Wherein (1), ^{Ar 11} represents a group forming a conjugated structure with ^{X 11} and ^{X 12} include an aromatic ^{ring, X 11} and ^{X 12} independently formula (1a) or (1b) The group represented by these is shown. In formula (1a) and formula (1b), Ar ¹² and Ar ¹³ each independently represent an aromatic hydrocarbon group having 6 or more carbon atoms, and R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently Represents a hydrogen atom, a halogen atom or a monovalent group, and X ¹³ , X ¹⁴ , X ¹⁵ and X ¹⁶ each independently represent an oxygen atom, a sulfur atom or a selenium atom. ]

The aromatic compound of the present invention has a long and high planar conjugated structure as a whole by having a group represented by the formula (1a) or (1b) at the terminal portion. Therefore, when applied as an organic semiconductor material, excellent charge transport properties can be exhibited.

In the aromatic compound of the present invention, the group represented by the formula (1a) or (1b) has an aromatic hydrocarbon group represented by Ar ¹² or Ar ¹³ at a portion located at the end of the conjugated structure. Have. By having an aromatic ring made of hydrocarbon at the end of the conjugated structure in this way, the aromatic compound has a stable molecular structure, and the charge transfer as an organic semiconductor material is repeated or a voltage is applied. However, it is difficult to disassemble. Therefore, when used as an organic semiconductor material, high stability can be exhibited, and as a result, excellent charge transportability can be maintained over a long period of time.

In the aromatic compound of the present invention, Ar ¹¹ is preferably a group represented by the formula (2).

[In Formula (2), Ar ²¹ , Ar ²² and Ar ²³ each independently have an aromatic hydrocarbon group having 6 or more carbon atoms which may have a substituent, or have a substituent. A heterocyclic group having 4 or more carbon atoms, wherein m, n and p are each independently an integer of 0 to 6 and m + n + p is an integer of 1 to 10; ]

As described above, when Ar ¹¹ is a group having a structure containing only an aromatic hydrocarbon group and / or a heterocyclic group, the conjugation property of the aromatic compound is further increased, and a more excellent charge transport property can be obtained. become.

At least one of X ¹³ and X ¹⁴ is preferably a sulfur atom, and at least one of X ¹⁵ and X ¹⁶ is preferably a sulfur atom. An aromatic compound having such a structure can exhibit further excellent charge transport properties.

Ar ¹² and Ar ¹³ are preferably a phenyl group or a naphthyl group. By having these groups at the terminal of the conjugated structure, the aromatic compound can exhibit extremely excellent stability in addition to high charge transportability.

More specifically, in the aromatic compound represented by the formula (1), Ar ¹¹ is a group represented by the formula (2), and X ¹³ , X ¹⁴ , X ¹⁵ and X ¹⁶ are sulfur atoms. Ar ¹² and Ar ¹³ are preferably phenyl groups. By having such a structure, particularly excellent charge transportability and stability can be obtained.

Further, at least one of Ar ²¹ , Ar ²² and Ar ²³ is preferably a thiophenediyl group which may have a substituent or a thienothiophenediyl group which may have a substituent. Thereby, it exists in the tendency for the charge transport property by an aromatic compound to improve further.

The present invention also provides an organic thin film containing the aromatic compound of the present invention, and an organic thin film element comprising such an organic thin film, particularly an organic thin film transistor and an organic photoelectric conversion element. Since the organic thin film of the present invention contains the aromatic compound of the present invention, it is possible to obtain excellent charge transportability and maintain such high charge transportability over a long period of time. Therefore, an organic thin film element such as an organic thin film transistor or an organic photoelectric conversion element provided with such an organic thin film can stably exhibit high charge transportability and has excellent practicality.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the aromatic compound applicable as an organic-semiconductor material which has the outstanding charge transport property and has high stability. In addition, an organic thin film containing such an aromatic compound and capable of stably exhibiting high charge transportability, and an organic thin film element such as an organic thin film transistor or an organic photoelectric conversion element having such an organic thin film are provided. It becomes possible to provide.

It is a schematic cross section of the organic thin-film transistor which concerns on 1st Embodiment. It is a schematic cross section of the organic thin-film transistor which concerns on 2nd Embodiment. It is a schematic cross section of the organic thin-film transistor which concerns on 3rd Embodiment. It is a schematic cross section of the organic thin-film transistor which concerns on 4th Embodiment. It is a schematic cross section of the organic thin-film transistor which concerns on 5th Embodiment. It is a schematic cross section of the organic thin-film transistor concerning 6th Embodiment. It is a schematic cross section of the organic thin-film transistor which concerns on 7th Embodiment. It is a schematic cross section of the solar cell which concerns on suitable embodiment. It is a schematic cross section of the photosensor concerning a 1st embodiment. It is a schematic cross section of the optical sensor which concerns on 2nd Embodiment. It is a schematic cross section of the photosensor concerning a 3rd embodiment.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(Aromatic compounds)
First, an aromatic compound according to a preferred embodiment will be described. The aromatic compound of the present embodiment is a conjugated compound having a structure represented by the above formula (1). Here, the conjugated compound has a structure in which a single bond and an unsaturated bond, a lone electron pair, a radical, or a non-bonding orbital are alternately connected in the main skeleton of a molecule, Refers to a compound that is delocalized.

The aromatic compound according to a preferred embodiment has a group that includes an aromatic ring and forms a conjugated structure with X ¹¹ and X ¹² as Ar ¹¹ . Such a group may be any group as long as it has at least one aromatic ring such as an aromatic hydrocarbon ring or an aromatic heterocyclic ring and can form a conjugated structure as a whole compound. Therefore, Ar ¹¹ may be a group that includes a chain structure other than an aromatic ring to form a conjugated structure.

The aromatic compound according to a preferred embodiment is one in which a group represented by the formula (1a) or the formula (1b) is bonded to the group represented by Ar ¹¹ as X ¹¹ or X ¹² . In the aromatic compound according to a preferred embodiment, the group represented by the formula (1a) or the formula (1b) is included in the group represented by Ar ¹¹ in addition to X ¹¹ or X ^12. May be.

Thus, the aromatic compound according to a preferred embodiment has a plurality of groups represented by the formula (1a) or the formula (1b), or groups represented by the formula (1a) and the formula (1b). In combination, this has high molecular planarity as a whole. Therefore, when used as an organic semiconductor material, the aromatic compound according to a preferred embodiment is a p-type semiconductor with good molecular packing and excellent charge transportability.

X ¹¹ and X ¹² may each independently be any of the groups represented by Formula (1a) and Formula (1b). Since the production of the aromatic compound according to the preferred embodiment can be facilitated and the packing of the molecule can be further improved, both X ¹¹ and X ¹² are groups represented by the formula (1a), or both are A group represented by the formula (1b) is more preferable. From this point of view, X ¹¹ and X ¹² are particularly preferably groups having the same structure.

In Formula (1a) or Formula (1b), Ar ¹² and Ar ¹³ each independently represent an aromatic hydrocarbon group having 6 or more carbon atoms. This aromatic hydrocarbon group may have groups represented by R ¹¹ and R ¹³ . The aromatic hydrocarbon group refers to a group composed of the remaining atomic group obtained by removing a hydrogen atom at a site used for bonding from an aromatic hydrocarbon ring. The aromatic hydrocarbon group has preferably 6 to 60 carbon atoms, more preferably 6 to 20 carbon atoms. The aromatic hydrocarbon ring includes a benzene ring and a condensed ring, and examples of the condensed ring include a naphthalene ring, an anthracene ring, a tetracene ring, a pentacene ring, a pyrene ring, a perylene ring, and a fluorene ring.

As the aromatic hydrocarbon group, a group consisting of the remaining atomic group obtained by removing two hydrogen atoms from a benzene ring or naphthalene ring is preferable. The aromatic hydrocarbon group may have one or more groups represented by R ¹¹ and R ¹³ , but the carbon number of the aromatic hydrocarbon group described above includes the carbon number of the substituent. Suppose that it is not possible. Specific examples of the group represented by R ¹¹ and R ¹³ will be described later. Among them, a hydrogen atom, a halogen atom, a saturated or unsaturated hydrocarbon group, an aryl group, an alkoxy group, an alkylthio group, an arylalkyl group, Examples include an aryloxy group, a monovalent heterocyclic group, an amino group, a nitro group, and a cyano group.

In the formula (1a) or the formula (1b), R ¹¹ , R ¹² , R ¹³ and R ¹⁴ (referred to as “R ¹¹ to R ¹⁴ ”, hereinafter, the same expressions are also expressed in the same manner) are each independently. , A hydrogen atom, a halogen atom or a monovalent group. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example.

Examples of the monovalent group include a group consisting of a linear or branched low molecular chain, a monovalent cyclic group having 3 to 60 carbon atoms (monocyclic, condensed ring, carbocyclic or heterocyclic ring, saturated Or may be unsaturated), saturated or unsaturated hydrocarbon group, hydroxyl group, alkoxy group, alkylthio group, alkanoyloxy group, amino group, oxyamino group, alkylamino group, dialkylamino group, alkanoylamino group, cyano group , A nitro group, a sulfo group, an alkyl group substituted with a halogen atom, an alkoxysulfonyl group, an alkylsulfonyl group, a sulfamoyl group, an alkylsulfamoyl group, a carboxyl group, a carbamoyl group, an alkylcarbamoyl group, an alkanoyl group and an alkoxycarbonyl group. Can be mentioned. Note that a substituent (such as a halogen atom) may further be bonded to the carbon atom in these groups.

Since the charge transport property and stability of the aromatic compound are further improved, R ¹¹ to R ¹⁴ are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms. It is more preferably an alkylthio group, and further preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms. Further, since the solubility in an organic solvent is improved, it is preferable that at least one of R ¹¹ and R ¹² and at least one of R ¹³ and R ¹⁴ are an alkyl group having 6 to 12 carbon atoms. In particular, since the solubility in an organic solvent is enhanced while improving the stability of the aromatic compound, R ¹¹ and R ¹³ are hydrogen atoms, and R ¹² and R ¹⁴ are alkyl groups having 6 to 12 carbon atoms. It is preferable.

Examples of the alkyl group include linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms, and linear, branched or cyclic alkyl groups having 1 to 12 carbon atoms are preferable. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, 3-methylbutyl group, pentyl group, hexyl group, 2-ethylhexyl group, heptyl group, octyl group , Nonyl group, decyl group, lauryl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, and cyclododecyl group.

Examples of the alkoxy group and the alkylthio group include an alkoxy group having 1 to 20 carbon atoms and an alkylthio group, and those having the above alkyl group in the structure can be exemplified. Among these, as the alkoxy group and the alkylthio group, those containing a linear, branched or cyclic alkyl group having 1 to 12 carbon atoms are preferable.

Further, in the formula (1a) or the formula (1b), X ¹³ to X ¹⁶ each independently represents an oxygen atom, a sulfur atom or a selenium atom. In order to obtain better charge transportability, it is preferable that at least one of X ¹³ and X ¹⁴ is a sulfur atom, and at least one of X ¹⁵ and X ¹⁶ is a sulfur atom, and all of X ¹³ to X ¹⁶ are sulfur. More preferably, it is an atom.

As the aromatic compound, it is preferable that the Ar ¹¹ is a group represented by the above formula (2) because a more excellent charge transport property tends to be obtained.

In the group represented by the formula (2), Ar ²¹ , Ar ²² and Ar ²³ are each independently an aromatic hydrocarbon group having 6 or more carbon atoms which may have a substituent, or a substituent. It is a heterocyclic group having 4 or more carbon atoms which may be present. Examples of the aromatic hydrocarbon group include the same groups as the aromatic hydrocarbon groups exemplified as Ar ¹² and Ar ¹³ described above.

The heterocyclic group refers to a group consisting of the remaining atomic group obtained by removing a hydrogen atom at a site used for bonding from a heterocyclic compound. A heterocyclic compound is an organic compound having a cyclic structure, and the elements constituting the ring are not only carbon atoms, but also heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, phosphorus atoms, boron atoms, silicon atoms, etc. In the ring. When Ar ²¹ , Ar ²² or Ar ²³ is a heterocyclic group, the corresponding group constitutes a corresponding heterocyclic ring. As the heterocyclic group, an aromatic heterocyclic group is preferable.

The number of carbon atoms of the heterocyclic group is preferably 4 to 60, and more preferably 4 to 20. The heterocyclic group may have one or more substituents. In that case, the carbon number of the heterocyclic group does not include the carbon number of the substituent. Substituents include halogen atoms, saturated or unsaturated hydrocarbon groups, aryl groups, alkoxy groups, alkylthio groups, arylalkyl groups, aryloxy groups, monovalent heterocyclic groups, amino groups, nitro groups, and cyano groups. Can be mentioned.

Heterocyclic groups include thiophene rings, rings with 2-6 condensed thiophene rings (thienothiophene ring, dithienothiophene ring, etc.), rings with 2-6 thiophene rings and benzene rings (benzothiophene ring) , Benzodithiophene ring, benzothienothiophene ring, dibenzothienothiophene ring, etc.), cyclopentadithiophene ring, thiazole ring, pyrrole ring, pyridine ring, pyrimidine ring, pyrazine ring, remaining after removing two hydrogen atoms from triazine ring The group which consists of these atomic groups is illustrated. Among them, a thiophene ring, a group consisting of the remaining atomic groups obtained by removing 2 hydrogen atoms from a ring condensed with 2 to 6 thiophene rings (thienothiophene ring, dithienothiophene ring), thiophene ring and benzene ring are 2 A group consisting of the remaining atomic groups obtained by removing 2 hydrogen atoms from a ring condensed with 6 to 6 rings is preferred. In particular, a group composed of the remaining atomic group obtained by removing two hydrogen atoms from a thiophene ring or thienothiophene ring is preferable. These suitable heterocyclic groups exhibit characteristic electrical properties such that they can emit electrons at a desired potential to assume a stable radical cation state.

Aromatic compounds are expected to have high charge transport properties as organic p-type semiconductors. Therefore, in order to enhance this effect, the planarity of the π-conjugated structure of the group represented by Ar ¹¹ , particularly the group represented by the formula (2), is enhanced, and a π-π stack structure is easily obtained. It is preferable. From such a viewpoint, Ar ²¹ , Ar ²² and Ar ²³ are preferably a structure containing a condensed ring or a thiophene ring. In particular, a structure including a thiophene ring is more preferable because the plane spacing of the π-π stack structure can be reduced. Therefore, at least one of Ar ²¹ , Ar ²² and Ar ²³ is preferably a thiophenediyl group which may have a substituent or a thienothiophenediyl group which may have a substituent, and Ar ²¹ , Ar It is particularly preferable that all of ²² and Ar ²³ are a thiophenediyl group which may have a substituent or a thienothiophenediyl group which may have a substituent.

Moreover, in order to improve the solubility with respect to the organic solvent of an aromatic compound, and hold | maintain (pi) conjugation planarity, it is preferable that at least 1 of Ar < ²¹ >, Ar < ²² > and Ar < ²³ > has a substituent. . As this substituent, an alkyl group is preferable, and an alkyl group having 6 to 12 carbon atoms is more preferable.

In the group represented by the formula (2), m, n and p are each independently an integer of 0 to 6, and m + n + p is an integer of 1 to 10. In particular, m + n + p is more preferably an integer of 1 to 3 because high charge transportability and stability can be obtained and the production of the aromatic compound can be facilitated.

As the aromatic compound represented by the formula (1), among them, X ¹¹ and X ¹² are groups represented by the formula (1a), Ar ¹¹ is a group represented by the formula (2), Moreover, a compound in which Ar ¹² is a phenyl group and X ¹³ and X ¹⁴ are sulfur atoms is preferable because the effects of the present invention can be obtained particularly well. Such an aromatic compound is represented by Formula (3). In the formula (3), R ¹¹ , R ¹² , Ar ²¹ , Ar ²² , Ar ²³ , m, n and p are all as defined above, and a plurality of groups having the same sign present in the molecule are Each may be the same or different.

Examples of the aromatic compound represented by the formula (1) include compounds represented by the following formulas (11) to (24). In the formulas (11) to (24), m ′ and n ′ each independently represent an integer of 1 to 20, and preferably an integer of 6 to 12.

Next, a preferred embodiment of the method for producing an aromatic compound as described above will be described.

The aromatic compound represented by the formula (1) is, for example, a raw material compound for forming a group represented by X ¹¹ and X ^12, that is, a group represented by the formula (1a) and / or the formula (1b). And a raw material compound for forming a group represented by Ar ¹¹ can be prepared, and then reacted. In the following description, a method for forming a group represented by the typical formula (1a) will be described as an example of X ¹¹ and X ¹² .

As a raw material compound for forming a group represented by the formula (1a), a compound represented by the following formula (30), and as a raw material compound for forming a group represented by Ar ¹¹ , Examples thereof include compounds represented by the following formula (31).

In formulas (30) and (31), R ¹¹ , R ¹² , Ar ¹¹ , Ar ¹² , X ¹³ and X ¹⁴ are all as defined above. W ⁰ , W ¹ and W ² are hydrogen atom, halogen atom, alkylsulfonate group, arylsulfonate group, arylalkylsulfonate group, alkylstannyl group, arylstannyl group, arylalkylstannyl group, boric acid ester residue Group, sulfonium methyl group, phosphonium methyl group, phosphonate methyl group, monohalogenated methyl group, boric acid residue (—B (OH) ₂ ), formyl group and vinyl group. Of these, a halogen atom, an alkylstannyl group, and a borate ester residue are preferable. Examples of the boric acid ester residue include a group represented by the following formula.

Since the compound represented by the formula (31) can be easily synthesized and the reaction between the raw material compounds becomes good, W ¹ and W ² are each independently a halogen atom, an alkyl sulfonate group, an aryl sulfonate group, An arylalkyl sulfonate group, a boric acid ester residue, a boric acid residue or a trialkylstannyl group is preferred.

Here, the raw material compound represented by Formula (30) can be synthesized, for example, according to the procedure represented by the following reaction scheme.

In the formulas (I) to (VI) and the formula (30), R ¹¹ , R ¹² , Ar ¹² , X ¹³ , X ¹⁴ and W ⁰ are as defined above, and X ³¹ and X ³² are each independently Represents a halogen atom.

Examples of the method for producing an aromatic compound using the raw material compound described above include, for example, a method using a Suzuki coupling reaction, a method using a Grignard reaction, a method using a Stille reaction, a method using a Ni (0) catalyst, A method using an oxidant such as FeCl _{3, a} method using an anion oxidation reaction, a method using palladium acetate and an organic base, a method of oxidative coupling by preparing an α-unsubstituted or halogenated lithio isomer, and electrochemical Examples thereof include a method using an oxidation reaction and a method by decomposing an intermediate compound having an appropriate leaving group. These can be selected according to the structure of the raw material compound and the target aromatic compound.

Among these, a method using a Suzuki coupling reaction, a method using a Grignard reaction, a method using a Stille reaction, a method using a Ni (0) catalyst, a method using an anion oxidation reaction, a method using palladium acetate and an organic base However, it is preferable because the structure of the aromatic compound is easily controlled, the raw material compound is easily obtained, and the reaction operation is easily simplified.

In the case of the Suzuki coupling reaction, for example, palladium [tetrakis (triphenylphosphine)] or palladium acetate is used as a catalyst, an inorganic base such as potassium carbonate, sodium carbonate, or barium hydroxide, an organic base such as triethylamine, or a fluoride. An inorganic salt such as cesium is added in an amount equal to or greater than the monomer, preferably 1 to 10 equivalents, and the raw material compound is reacted. Moreover, you may make it react by a two-phase system by making inorganic salt into aqueous solution.

Examples of the solvent used in this reaction include N, N-dimethylformamide, toluene, dimethoxyethane, and tetrahydrofuran. The reaction temperature depends on the solvent used, but is preferably 50 to 160 ° C. In the reaction, the temperature may be raised to near the boiling point of the solvent and refluxed. The preferred reaction time is 1 to 200 hours. Such a Suzuki coupling reaction can be performed in accordance with, for example, the method described in Chemical Review (Chem. Rev.), Vol. 95, p. 2457 (1995).

In the case of a reaction using a Ni (0) catalyst, in addition to a method using a zero-valent nickel complex as a Ni (0) catalyst, a method in which a nickel salt is reacted in the presence of a reducing agent to generate zero-valent nickel in the system. There is. Examples of the zerovalent nickel complex include bis (1,5-cyclooctadiene) nickel (0), (ethylene) bis (triphenylphosphine) nickel (0), and tetrakis (triphenylphosphine) nickel. Of these, bis (1,5-cyclooctadiene) nickel (0) is preferred because of its high versatility and low cost.

Moreover, in the reaction using a Ni (0) catalyst, it is more preferable to add a neutral ligand to the system because the yield is improved. Here, the neutral ligand is a ligand having no anion or cation. For example, nitrogen-containing ligands such as 2,2′-bipyridyl, 1,10-phenanthroline, methylenebisoxazoline, N, N′-tetramethylethylenediamine; triphenylphosphine, tolylphosphine, tributylphosphine, triphenoxyphosphine, etc. Of the third phosphine ligand. Of these, nitrogen-containing ligands are preferred because they are versatile and inexpensive. In particular, 2,2'-bipyridyl is preferable because high reactivity can be obtained and a high yield can be achieved. More specifically, since the yield of the aromatic compound is improved, 2,2′-bipyridyl is added as a neutral ligand to a system containing bis (1,5-cyclooctadiene) nickel (0). It is preferable to carry out the reaction.

On the other hand, in the method of generating zero-valent nickel in the system, nickel chloride or nickel acetate can be used as the nickel salt. Examples of the reducing agent include zinc, sodium hydride, hydrazine and derivatives thereof, and lithium aluminum hydride. Moreover, you may use together ammonium iodide, lithium iodide, potassium iodide etc. as an additive as needed.

In the Stille reaction, for example, palladium [tetrakis (triphenylphosphine)] or palladium acetate is used as a catalyst, and the reaction is performed using an organic tin compound as a monomer. Examples of the solvent used in this reaction include N, N-dimethylformamide, toluene, dimethoxyethane, and tetrahydrofuran. The reaction temperature depends on the solvent used, but is preferably 50 to 160 ° C. Further, the temperature may be raised to near the boiling point of the solvent and refluxed. The reaction time is preferably 1 to 200 hours.

In the case of a method using an anion oxidation reaction, a halogen-substituted product or hydrogen-substituted product such as a raw material compound is used as a monomer and reacted with n-butyllithium to prepare a lithiated compound, which is obtained by using copper (II) bromide, Treat with an oxidizing agent such as copper (II) chloride or iron (III) acetylacetonate. Examples of the solvent used in this reaction include toluene, dimethoxyethane, tetrahydrofuran, hexane, heptane, and octane. The reaction temperature depends on the solvent used, but is preferably 50 to 160 ° C. Further, the temperature may be raised to near the boiling point of the solvent and refluxed. The reaction time is preferably 5 minutes to 200 hours.

In the method using palladium acetate and an organic base, a halogen-substituted product is used as a monomer, and the reaction is carried out by adding palladium (II) acetate and an organic base such as diisopropylamine or triethylamine. Examples of the solvent used in this reaction include N, N-dimethylformamide, toluene, dimethoxyethane, and tetrahydrofuran. The reaction temperature depends on the solvent used, but is preferably 50 to 160 ° C. Further, the temperature may be raised to near the boiling point of the solvent and refluxed. The reaction time is preferably 5 minutes to 200 hours.

(Organic thin film)
Next, an organic thin film according to a preferred embodiment will be described.

The organic thin film according to a preferred embodiment contains the above-described aromatic compound. In addition, the organic thin film may contain one kind of aromatic compound independently, and may contain two or more kinds of aromatic compounds. In addition, in order to increase the electron transport property or hole transport property, the organic thin film has a low molecular compound having electron transport property or hole transport property other than the aromatic compound, or an electron transport property different from the aromatic compound or A polymer compound having a hole transport property (these low molecular compounds and polymer compounds are collectively referred to as “electron transport material” and “hole transport material”) may be included.

Examples of the hole transport material include pyrazoline, arylamine, stilbene, triaryldiamine, oligothiophene, polyvinylcarbazole, polysilane, polysiloxane having an aromatic amine in the side chain or main chain, polyaniline, polythiophene, polypyrrole, polyarylene. Examples include vinylene, polythienylene vinylene, and derivatives thereof.

Examples of the electron transporting material include oxadiazole, anthraquinodimethane, benzoquinone, naphthoquinone, anthraquinone, tetracyanoanthraquinodimethane, fluorenone, diphenyldicyanoethylene, diphenoquinone, 8-hydroxyquinoline metal complex, polyquinoline, polyquinoline, quinoxaline, polyfluorenes, fullerenes such as C _60, and derivatives thereof.

In addition, the organic thin film of this embodiment may include a charge generation material in order to generate a charge by light absorbed in the organic thin film. Examples of the charge generating material, for example, azo compounds, diazo compounds, metal-free phthalocyanine compounds, metal phthalocyanine compounds, perylene compounds, polycyclic quinone compounds, squarylium compounds, azulenium compounds, fullerenes such thiapyrylium compounds and C ₆₀ and the like .

Furthermore, the organic thin film may further contain materials necessary for developing various functions. Such materials include, for example, a sensitizer for sensitizing the function of generating charge by absorbed light, a stabilizer for increasing stability, and UV absorption for absorbing ultraviolet (UV) light. Agents.

In addition, the organic thin film may contain a polymer compound material other than the compounds exemplified as the above-described components as a polymer binder in order to improve mechanical properties. As the polymer binder, those that do not extremely inhibit the electron transport property or hole transport property are preferable, and those that do not strongly absorb visible light are preferable.

Examples of the polymer binder include poly (N-vinylcarbazole), polyaniline, polythiophene, poly (p-phenylene vinylene), poly (2,5-thienylene vinylene), polycarbonate, polyacrylate, polymethyl acrylate, and polymethyl. Examples include methacrylate, polystyrene, polyvinyl chloride, polysiloxane, and derivatives thereof.

Examples of the method for producing the organic thin film of the present embodiment include, for example, an aromatic compound, an electron transporting material, a hole transporting material, a solution containing a polymer binder and a solvent to be mixed as necessary (that is, a composition). The method by the film-forming using is mentioned. Moreover, when an aromatic compound has sublimability, an organic thin film can also be formed by a vacuum evaporation method. In the case where an aromatic compound is used as a material for an organic thin film, the purity affects the device characteristics. Therefore, even if purification is performed by a method such as sublimation purification or recrystallization before the production of the organic thin film. Good.

In the case of performing film formation using a solution, the solvent used in the solution may be any solvent that can dissolve the aromatic compound, the electron transporting material or hole transporting material to be mixed, and the polymer binder. For example, unsaturated hydrocarbon solvents such as toluene, xylene, mesitylene, tetralin, decalin, bicyclohexyl, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutane, Halogenated saturated hydrocarbon solvents such as bromobutane, chloropentane, bromopentane, chlorohexane, bromohexane, chlorocyclohexane, bromocyclohexane, halogenated unsaturated hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene, tetrahydrofuran, tetrahydro An ether solvent such as pyran can be used. Aromatic compound, depending on the structure and molecular weight of the compound can be dissolved 0.1 by weight% or more in these solvents.

Film formation methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, screen printing, flexographic printing. Application methods such as offset printing, ink jet printing, dispenser printing, nozzle coating and capillary coating can be used. Of these, spin coating, flexographic printing, ink jet printing, dispenser printing, nozzle coating, and capillary coating are preferred.

The thickness of the organic thin film is preferably 1 nm to 100 μm, more preferably 2 nm to 1000 nm, still more preferably 5 nm to 500 nm, and particularly preferably 20 nm to 200 nm.

Further, when the organic thin film is oriented with an aromatic compound, the main chain or side chain of the aromatic compound is arranged in one direction, so that higher charge mobility tends to be obtained. Therefore, the step of manufacturing the organic thin film may include a step of orienting the aromatic compound.

As a method for aligning the aromatic compound, a method known as a liquid crystal alignment method can be used. Among them, the rubbing method, the photo-alignment method, the sharing method (shear stress application method) and the pulling coating method tend to be simple and useful as the alignment method and easy to use. In particular, the rubbing method and the sharing method are preferable.

Since the organic thin film has a charge transporting property, it can control the transport of charges injected from the electrodes and the charges generated by light absorption. The organic thin film transistor, the organic photoelectric conversion element (organic solar cell, It can be used for organic thin film elements such as optical sensors. When an organic thin film is used for these organic thin film elements, the charge transporting property tends to be further improved if the aromatic compound is aligned by the alignment treatment.

(Organic thin film element)
Next, an organic thin film element according to a preferred embodiment will be described. Preferable examples of the organic thin film element to which the organic thin film containing the aromatic compound described above is applied include an organic thin film transistor and an organic photoelectric conversion element. Hereinafter, a solar cell and an optical sensor which are examples of the organic thin film transistor and the organic photoelectric conversion element will be described.

First, an organic thin film transistor includes, for example, a source electrode and a drain electrode, an active layer (organic thin film layer) made of an organic thin film containing an aromatic compound as a current path between them, and a gate electrode for controlling the amount of current passing through the current path. It has the structure provided. Examples of such an organic thin film transistor include a field effect type and an electrostatic induction type.

A field-effect organic thin film transistor includes a source electrode and a drain electrode, an active layer containing an aromatic compound as a current path between them, a gate electrode for controlling the amount of current passing through the current path, and between the active layer and the gate electrode. It is preferable to provide an insulating layer disposed on the surface. In particular, the source electrode and the drain electrode are preferably provided in contact with the active layer containing an aromatic compound, and the gate electrode is preferably provided with an insulating layer in contact with the active layer interposed therebetween.

The electrostatic induction type organic thin film transistor has a source electrode and a drain electrode, an active layer that becomes a current path between them and contains an aromatic compound, and a gate electrode that controls an amount of current passing through the current path. Is preferably provided in the active layer. In particular, the source electrode, the drain electrode, and the gate electrode provided in the active layer are preferably provided in contact with the active layer containing the aromatic compound. The structure of the gate electrode may be any structure as long as a current path flowing from the source electrode to the drain electrode is formed and the amount of current flowing through the current path can be controlled by a voltage applied to the gate electrode. It is done.

FIG. 1 is a schematic cross-sectional view of an organic thin film transistor (field effect organic thin film transistor) according to a first embodiment. An organic thin film transistor 100 shown in FIG. 1 includes a substrate 1, a source electrode 5 and a drain electrode 6 formed on the substrate 1 with a predetermined interval, and a source electrode 5 and a drain electrode 6 so as to cover the substrate 1. Formed on the insulating layer 3 so as to cover the region of the insulating layer 3 between the source electrode 5 and the drain electrode 6, the insulating layer 3 formed on the active layer 2, and the insulating layer 3 formed between the source electrode 5 and the drain electrode 6. And a gate electrode 4.

FIG. 2 is a schematic cross-sectional view of an organic thin film transistor (field effect organic thin film transistor) according to a second embodiment. An organic thin film transistor 110 shown in FIG. 2 includes a substrate 1, a source electrode 5 formed on the substrate 1, an active layer 2 formed on the substrate 1 so as to cover the source electrode 5, a source electrode 5 and a predetermined electrode. Of the drain electrode 6 formed on the active layer 2 with an interval of, the insulating layer 3 formed on the active layer 2 and the drain electrode 6, and the insulating layer 3 between the source electrode 5 and the drain electrode 6. And a gate electrode 4 formed on the insulating layer 3 so as to cover the region.

FIG. 3 is a schematic cross-sectional view of an organic thin film transistor (field effect organic thin film transistor) according to a third embodiment. The organic thin film transistor 120 shown in FIG. 3 includes a substrate 1, an active layer 2 formed on the substrate 1, a source electrode 5 and a drain electrode 6 formed on the active layer 2 with a predetermined interval, and a source electrode. 5 and the drain electrode 6 so as to partially cover the insulating layer 3 formed on the active layer 2, the region of the insulating layer 3 where the source electrode 5 is formed below, and the drain electrode 6 are formed below. And a gate electrode 4 formed on the insulating layer 3 so as to partially cover the region of the insulating layer 3.

FIG. 4 is a schematic cross-sectional view of an organic thin film transistor (field effect organic thin film transistor) according to a fourth embodiment. 4 includes a substrate 1, a gate electrode 4 formed on the substrate 1, an insulating layer 3 formed on the substrate 1 so as to cover the gate electrode 4, and the gate electrode 4 at the bottom. The source electrode 5 and the drain electrode 6 formed on the insulating layer 3 at a predetermined interval so as to partially cover the region of the insulating layer 3 formed on the substrate, and the source electrode 5 and the drain electrode 6 are partially covered. Thus, the active layer 2 formed on the insulating layer 3 is provided.

FIG. 5 is a schematic cross-sectional view of an organic thin film transistor (field effect organic thin film transistor) according to a fifth embodiment. An organic thin film transistor 140 shown in FIG. 5 includes a substrate 1, a gate electrode 4 formed on the substrate 1, an insulating layer 3 formed on the substrate 1 so as to cover the gate electrode 4, and the gate electrode 4 at the bottom. A source electrode 5 formed on the insulating layer 3 so as to partially cover the region of the insulating layer 3 formed on the active layer 2 and an active layer 2 formed on the insulating layer 3 so as to partially cover the source electrode 5. And a drain electrode 6 formed on the insulating layer 3 at a predetermined interval so as to partially cover the region of the active layer 2 formed below the gate electrode 4 It is.

FIG. 6 is a schematic cross-sectional view of an organic thin film transistor (field effect organic thin film transistor) according to a sixth embodiment. An organic thin film transistor 150 shown in FIG. 6 includes a substrate 1, a gate electrode 4 formed on the substrate 1, an insulating layer 3 formed on the substrate 1 so as to cover the gate electrode 4, and the gate electrode 4 at the bottom. The active layer 2 is formed on the insulating layer 3 so as to partially cover the region of the active layer 2 formed under the active layer 2 and the gate electrode 4 formed below. The source electrode 5 and the drain electrode 6 formed on the insulating layer 3 with a predetermined distance from the source electrode 5 so as to partially cover the region of the active layer 2 where the gate electrode 4 is formed below. , Are provided.

FIG. 7 is a schematic cross-sectional view of an organic thin film transistor (static induction organic thin film transistor) according to a seventh embodiment. The organic thin film transistor 160 shown in FIG. 7 includes a substrate 1, a source electrode 5 formed on the substrate 1, an active layer 2 formed on the source electrode 5, and a plurality on the active layer 2 with a predetermined interval. The formed gate electrode 4 and the active layer 2a formed on the active layer 2 so as to cover the gate electrode 4 (the material constituting the active layer 2a may be the same as or different from that of the active layer 2). And a drain electrode 6 formed on the active layer 2a.

In the organic thin film transistors according to the first to seventh embodiments, the active layer 2 and / or the active layer 2a contains the aromatic compound of the present invention, and the current path between the source electrode 5 and the drain electrode 6 ( Channel). The gate electrode 4 controls the amount of current passing through the current path (channel) in the active layer 2 and / or the active layer 2a by applying a voltage.

The field effect organic thin film transistor of the above-described form can be manufactured by a known method, for example, a method described in JP-A-5-110069. The electrostatic induction organic thin film transistor can be produced by a known method, for example, a method described in JP-A-2004-006476.

As a material of the substrate 1, a glass substrate, a flexible film substrate, and a plastic substrate can be used as long as the characteristics as an organic thin film transistor are not impaired.

When forming the active layer 2, it is advantageous in production and preferable that the aromatic compound is soluble in an organic solvent. In that case, the organic thin film used as the active layer 2 can be formed by applying the manufacturing method of the organic thin film by application | coating using a solution as demonstrated above.

As the insulating layer 3 in contact with the active layer 2, any material having high electrical insulation may be used, and a known material can be used. For _{example, SiOx, SiNx, Ta 2 O} 5, polyimide, polyvinyl alcohol, polyvinyl phenol, organic glass and photoresists. Since the voltage can be lowered, the insulating layer 3 is preferably a material having a high dielectric constant.

When forming the active layer 2 on the insulating layer 3, in order to improve the interface characteristics between the insulating layer 3 and the active layer 2, the surface of the insulating layer 3 is treated with a surface treatment agent such as a silane coupling agent. It is also possible to form the active layer 2 after surface modification. Examples of the surface treatment agent include silylamine compounds such as long-chain alkylchlorosilanes, long-chain alkylalkoxysilanes, fluorinated alkylchlorosilanes, fluorinated alkylalkoxysilanes, and hexamethyldisilazane. Prior to the treatment with the surface treatment agent, the surface of the insulating layer 3 can be treated with ozone UV or O ₂ plasma.

In addition, after manufacturing the organic thin film transistor, it is preferable to form a protective film on the organic thin film transistor in order to protect the element. Thereby, an organic thin-film transistor can be interrupted | blocked from air | atmosphere, and it becomes possible to suppress the fall of the characteristic of an organic thin-film transistor. Moreover, when forming the display device driven on an organic thin-film transistor, the influence on the organic thin-film transistor by the manufacturing process of a display device can be reduced with a protective film.

Examples of the method for forming the protective film include a method of covering the organic thin film transistor with a UV curable resin, a thermosetting resin, or an inorganic SiONx film. In order to effectively shut off from the atmosphere, the steps from the preparation of the organic thin film transistor to the formation of the protective film are performed without exposure to the atmosphere (for example, in a dry nitrogen atmosphere or in a vacuum). Is preferred.

Next, a preferred embodiment of the organic photoelectric conversion element will be described. Typical examples of the organic photoelectric conversion element include a solar cell and an optical sensor as described above.

FIG. 8 is a schematic cross-sectional view showing a solar cell according to a preferred embodiment. The solar cell 200 shown in FIG. 8 includes an active layer 2 made of a substrate 1, a first electrode 7a formed on the substrate 1, and an organic thin film containing an aromatic compound formed on the first electrode 7a. And a second electrode 7 b formed on the active layer 2.

In the solar cell 200, a transparent or translucent electrode is used for one of the first electrode 7a and the second electrode 7b. As an electrode material, metals such as aluminum, gold, silver, copper, alkali metal, alkaline earth metal, and semi-transparent films and transparent conductive films thereof can be used. The electrode material is preferably selected so that the work function difference between the first electrode 7a and the second electrode 7b is large in order to obtain a high open circuit voltage. In addition, a charge generating agent, a sensitizer, or the like may be added to the active layer 2 in order to increase photosensitivity. As the substrate 1, a silicon substrate, a glass substrate, a plastic substrate, or the like can be used.

FIG. 9 is a schematic cross-sectional view showing the photosensor according to the first embodiment. An optical sensor 300 shown in FIG. 9 includes an active layer 2 made of a substrate 1, a first electrode 7a formed on the substrate 1, and an organic thin film containing an aromatic compound formed on the first electrode 7a. And a charge generation layer 8 formed on the active layer 2 and a second electrode 7b formed on the charge generation layer 8.

FIG. 10 is a schematic cross-sectional view of an optical sensor according to the second embodiment. An optical sensor 310 illustrated in FIG. 10 is formed on the substrate 1, the first electrode 7a formed on the substrate 1, the charge generation layer 8 formed on the first electrode 7a, and the charge generation layer 8. And an active layer 2 made of an organic thin film containing an aromatic compound, and a second electrode 7b formed on the active layer 2.

Furthermore, FIG. 11 is a schematic cross-sectional view of an optical sensor according to the third embodiment. An optical sensor 320 shown in FIG. 11 includes an active layer 2 made of an organic thin film containing a substrate 1, a first electrode 7a formed on the substrate 1, and an aromatic compound formed on the first electrode 7a. And a second electrode 7 b formed on the active layer 2.

In the optical sensors according to the first to third embodiments, a transparent or translucent electrode is used as one of the first electrode 7a and the second electrode 7b. As an electrode material, metals such as aluminum, gold, silver, copper, alkali metal, alkaline earth metal, and their translucent films and transparent conductive films can be used. The charge generation layer 8 is a layer that absorbs light and generates charges. In addition, a carrier generating agent, a sensitizer, or the like may be added to the active layer 2 in order to increase photosensitivity. Furthermore, as the base material 1, a silicon substrate, a glass substrate, a plastic substrate, etc. can be used.

As mentioned above, although this invention was demonstrated in detail based on the embodiment, this invention is not limited to said embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary of this invention.

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

[Measurement condition]
Conditions for various analyzes and the like performed in the following synthesis examples and examples are shown. That is, first, nuclear magnetic resonance (NMR) spectrum was measured using JNM-GSX-400 manufactured by JEOL. Wako Gel C-200 manufactured by Wako Pure Chemical Industries, Ltd. was used as the silica gel in the column chromatography separation.

Cyclic voltammetry uses the product name “CV-50W” manufactured by BAS Co., Ltd. (BAS) as a measuring device, a Pt electrode manufactured by BAS as a working electrode, a Pt wire as a counter electrode, and a reference electrode It measured using the Ag line. During this measurement, the sweep speed was 100 mV / second, and the scanning potential region was 0 to 1.2V. The oxidation potential was measured by completely dissolving 3 × 10 ⁻³ mol / L of the compound and 0.1 mol / L of tetrabutylammonium hexafluorophosphate (TBAPF6) as a supporting electrolyte in a dichloromethane solvent.

The oxidation potential (E ^1/2 ox) was determined as the rising potential of the oxidation wave. The HOMO (maximum occupied molecular orbital) level was determined from the first oxidation potential with ferrocene as an internal standard (oxidation potential -0.21 V, 4.8 eV from the vacuum level). The ultraviolet (UV) absorption spectrum was measured by using a trade name “UV-2500PC” manufactured by Shimadzu Corporation as a measuring apparatus and dissolving the compound in chloroform at a concentration of 5 × 10 ⁻⁶ M. The energy band gap was determined from the UV absorption edge wavelength.

For the ionization potential, use the atmospheric photoelectron spectrometer (AC-2) manufactured by Riken Keiki Co., Ltd., and plot the relationship between irradiation light energy and (photoelectron emission number) ^1/2. Asked.

[Synthesis of aromatic compounds]
<Example 1>
Synthesis Example 1: Synthesis of 3-chloro-N-methoxy-N-methylbenzo [b] thiophene-2-carboxamide
First, the starting material 3-chlorobenzo [b] thiophene-2-carbonyl chloride is referred to the description in the reference (T. Higa, AJ Krubsack, J. Org. Chem., 1975, 21, 3037). And synthesized.

This was then used to synthesize 3-chloro-N-methoxy-N-methylbenzo [b] thiophene-2-carboxamide. Specifically, first, 462 mg (2.0 mmol) of 3-chlorobenzo [b] thiophene-2-carbonyl chloride obtained above and 215 mL (2.2 mmol) of N, O-dimethylhydroxylamine hydrochloride were added to a 50 mL eggplant flask. , 489 mg (4.8 mmol) of triethylamine and 10 mL of dichloromethane were added respectively, and they were stirred at room temperature for 4 hours.

The solution after the reaction was extracted with ether and dried over sodium sulfate, and then the solvent was distilled off. Thereafter, the product was purified by silica gel column chromatography using hexane containing 3% by weight of ethyl acetate as a developing solvent, and the desired 3-chloro-N-methoxy-N-methylbenzo [b] thiophene-2-carboxamide (formula (A ) Was obtained in the form of a pale yellow solid (388 mg, yield 76%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.97-7.91 (m, 1H), 7.84-7.79 (m, 1H), 7.52-7.46 ( m, 2H), 3.72 (s, 3H), 3.40 (s, 3H)

(Synthesis Example 2: Synthesis of 1- (3-chlorobenzo [b] thiophen-2-yl) tridecan-1-one)
To a 20 mL reactor, 300 mg (1.2 mmol) of the compound A obtained above and 5 mL of tetrahydrofuran (THF) were added, respectively. To this, 12 mL (6 mL) of a THF solution (0.50 M) of n-dodecylmagnesium bromide was added. 0.0 mmol), was injected using a syringe and stirred at room temperature for 2 hours.

Dilute hydrochloric acid was poured into the solution after the reaction to terminate the reaction, followed by extraction with ethyl acetate and further drying with sodium sulfate, and then the solvent was distilled off. Thereafter, the obtained reaction product is purified by silica gel column chromatography using hexane containing 1% by weight of ethyl acetate as a developing solvent to obtain the target 1- (3-chlorobenzo [b] thiophen-2-yl). Tridecan-1-one (Compound B represented by the following formula (B)) was obtained in the form of a yellowish white solid (213 mg, yield 49%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.97 (d, J = 8.0 Hz, 1H), 7.82 (d, J = 6.8 Hz, 1H), 7.55- 7.46 (m, 2H), 3.15 (t, J = 7.2 Hz, 2H), 1.84-1.72 (m, 2H), 1.46-1.20 (m, 18H), 0.88 (t, J = 7.6 Hz, 3H)

Synthesis Example 3: Synthesis of ethyl 3-dodecylbenzo [4,5] thieno [3,2-b] -2-thiophenecarboxylate
In a 20 mL reactor, 213 mg (0.58 mmol) of the compound B obtained above, 77.0 mg (0.64 mmol) of ethyl thioglycolate, 160 mg (1.16 mmol) of potassium carbonate, N, N-dimethyl 3 mL of formamide (DMF) was added respectively, and these were stirred at room temperature for 18 hours. Thereafter, an ethanol solution of sodium hydroxide (0.5 M, 0.4 mL) was added, and the mixture was further stirred for 2 hours.

The solution after this reaction was extracted with ether and dried over sodium sulfate, and then the solvent was distilled off. Thereafter, the obtained reaction solution is purified by silica gel column chromatography using hexane containing 0.5% by weight of ethyl acetate as a developing solvent, whereby the desired 3-dodecylbenzo [4,5] thieno [3, 2-b] -ethyl 2-thiophenecarboxylate (compound C represented by the following formula (C)) was obtained in the form of a yellow solid (224 mg, yield 90%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.90-7.84 (m, 2H), 7.46-7.38 (m, 2H), 4.39 (q, J = 7.2 Hz, 2H), 3.18 (t, J = 8.0 Hz, 2H), 1.80-1.70 (m, 2H), 1.46-1.20 (m, 21H),. 88 (t, J = 7.2Hz, 3H)

Synthesis Example 4: Synthesis of 3-dodecylbenzo [4,5] thieno [3,2-b] -2-thiophenecarboxylic acid
To a 100 mL eggplant flask, 294 mg (0.68 mmol) of Compound C obtained above, 114 mg (2.04 mmol) of potassium hydroxide, 1 mL of water and 5 mL of ethanol were added, and the mixture was stirred at 100 ° C. for 8 hours. did.

After distilling off ethanol from the solution after this reaction, dilute hydrochloric acid was added and the precipitated solid was separated by suction filtration to obtain the desired 3-dodecylbenzo [4,5] thieno [3,2-b]- 2-thiophenecarboxylic acid (Compound D represented by the following formula (D)) was obtained as a white solid (240 mg, yield 88%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.94-7.89 (m, 1H), 7.89-7.84 (m, 1H), 7.48-7.40 ( m, 2H), 3.23 (t, J = 7.6 Hz, 2H), 1.85-1.74 (m, 2H), 1.46-1.20 (m, 18H), 0.87 ( t, J = 7.2 Hz, 3H)

(Synthesis Example 5: Synthesis of 3-dodecylbenzo [4,5] thieno [3,2-b] thiophene)
To a 50 mL eggplant flask, 220 mg (0.55 mmol) of the compound D obtained above, 35 mg (0.55 mmol) of copper powder, and 3.5 mL of quinoline were added, and these were added at 260 ° C. for 4 hours under a nitrogen atmosphere. Stir.

The solution after this reaction was extracted with ether, the organic layer was dried over sodium sulfate, and the solvent was distilled off. The obtained residue is purified by silica gel column chromatography using hexane as a developing solvent to obtain the desired 3-dodecylbenzo [4,5] thieno [3,2-b] thiophene (the following formula (E) Was obtained as a pale yellow solid (192 mg, yield 98%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.84 (d, J = 8.4 Hz, 1H), 7.82 (d, J = 7.6 Hz, 1H), 7.09 ( s, 1H), 2.75 (t, J = 8.0 Hz, 2H), 1.82-1.71 (m, 2H), 1.46-1.20 (m, 18H), 0.88 ( t, J = 6.8 Hz, 3H)

(Synthesis Example 6: Synthesis of 2-bromo-3-dodecylbenzo [4,5] thieno [3,2-b] thiophene)
To a 100 mL eggplant flask, 192 mg (0.54 mmol) of the compound E obtained above, 127 mg (0.72 mmol) of N-bromosuccinimide (NBS), and 5 mL of DMF were added and stirred at room temperature for 5 hours.

The solution after this reaction was extracted with ether, and then the organic layer was taken out and dried over sodium sulfate. Thereafter, the residue obtained by distilling off the solvent was purified by silica gel column chromatography using hexane as a developing solvent to obtain the desired 2-bromo-3-dodecylbenzo [4,5] thieno [3, 2-b] thiophene (compound F represented by the following formula (F)) was obtained in the form of an orange solid (199 mg, yield 84%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.82 (d, J = 8.0 Hz, 1H), 7.74 (d, J = 8.8 Hz, 1H), 7.52- 7.46 m, 2H), 7.32 (dd, J = 7.2 Hz, 1H), 2.76 (t, J = 7.2 Hz, 2H), 1.77-1.68 (m, 2H), 1.50-1.20 (m, 18H), 0.87 (t, J = 7.6 Hz, 3H)

Synthesis Example 7 Synthesis of 5,5′-bis (3-dodecylbenzo [4,5] thieno [3,2-b] -2-thienyl) -2,2-bithiophene
In a 20 mL eggplant flask, 86 mg (0.20 mmol) of the compound F obtained above, 62 mg (0.083 mmol) of 5,5′-bis (n-tributylstannyl) -2,2′-bithiophene, tetrakis 12.1 mg (0.011 mmol) of (triphenylphosphine) palladium, 2 mL of DMF, and 2 mL of toluene were added, and the mixture was stirred at 85 ° C. for 24 hours.

The solution after this reaction was extracted with toluene, and the organic layer was filtered through silica gel. After toluene was distilled off from the organic layer after filtration, the residue was washed with acetone, and further recrystallized using toluene-hexane to obtain 5,5′-bis ( 3-dodecylbenzo [4,5] thieno [3,2-b] -2-thienyl) -2,2′-bithiophene (compound G represented by the following formula (G)) was converted into an orange solid (41 mg, yield). 60%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.86 (d, J = 8.4 Hz, 2H), 7.81 (d, J = 7.6 Hz, 2H), 7.42 ( dd, J = 7.6 Hz, 2H), 7.35 (dd, J = 7.6 Hz, 2H), 7.21 (d, J = 3.6 Hz, 2H), 7.14 (d, J = 3 .6 Hz, 2H), 2.98 (t, J = 7.6 Hz, 4H), 1.86-1.77 (m, 4H), 1.50-1.41 (m, 4H), 1.40 −1.20 (m, 36H), 0.86 (t, J = 7.2 Hz, 6H)

The energy band gap obtained from the UV absorption spectrum of Compound G was 2.6 eV. Further, the first / second oxidation potential obtained by cyclic voltammetry was 0.59 / 0.89V, and the HOMO level obtained from the first oxidation potential was 5.18 eV. The ionization potential determined by AC-2 was 5.4 eV.

<Example 2>
Synthesis Example 8 Synthesis of 2,5-bis (3-dodecylbenzo [4,5] thieno [3,2-b] -2-thienyl) thieno [3,2-b] thiophene
In a 20 mL eggplant flask, 90 mg (0.21 mmol) of compound F obtained in the same manner as in Example 1, and 63 mg of 2,5-bis (n-tributylstannyl) thieno [3,2-b] thiophene ( 0.09 mmol), 12.1 mg (0.011 mmol) of tetrakis (triphenylphosphine) palladium, 2 mL of DMF, and 2 mL of toluene were added, and the mixture was stirred at 85 ° C. for 24 hours.

The solution after this reaction was extracted with toluene, and then the organic layer was filtered through silica gel. After toluene was distilled off from the organic layer after filtration, the residue was washed with acetone, and further recrystallized with toluene and hexane to obtain 2,5-bis (3- Dodecylbenzo [4,5] thieno [3,2-b] -2-thienyl) thieno [3,2-b] thiophene (compound H represented by the following formula (H)) was converted into a yellow solid (44 mg, yield). The rate was 57%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm) = 7.87 (d, J = 8.0 Hz, 2H), 7.83 (d, J = 8.0 Hz, 2H), 7.42 (dd , J = 6.8 Hz, 2H), 7.37 (s, 2H), 7.36 (dd, J = 6.8 Hz, 2H), 3.00 (t, J = 8.0 Hz, 4H), 1 .87-1.78 (m, 4H), 1.50-1.41 (m, 4H), 1.38-1.22 (m, 36H), 0.86 (t, J = 7.2 Hz, 6H)

The energy band gap obtained from the UV absorption spectrum of Compound H was 2.7 eV. The first / second oxidation potential obtained by cyclic voltammetry was 0.67 / 1.07V, and the HOMO level obtained from the first oxidation potential was 5.26 eV. The ionization potential obtained by AC-2 was 5.6 eV.

<Example 3>
Synthesis Example 9 Synthesis of 1- (3-chlorobenzo [b] thiophen-2-yl) decan-1-ol
To a 100 mL eggplant flask, 3-chlorobenzo [b] thiophene-2-carboxylic acid (600 mg, 2.80 mmol), copper powder (178 mg, 2.80 mmol), and quinoline (5.0 mL) were added, under a nitrogen atmosphere. , And stirred at 260 ° C. for 5 hours. The solution after the reaction was extracted with ether and washed with dilute hydrochloric acid, and then the organic layer was dried over sodium sulfate, and the solvent was distilled off. The residue was purified by silica gel column chromatography using hexane as a developing solvent to obtain 3-chlorobenzo [b] thiophene as an orange liquid (470 mg, yield 99%).

3-Chlorobenzo [b] thiophene (260 mg, 1.54 mmol) was placed in a 20 mL three-necked flask and dissolved in THF (5 mL). Next, the gas in the three-necked flask was replaced with nitrogen and cooled to -78 ° C. Subsequently, n-butyllithium (1.57 M hexane solution, 1.1 mL, 1.7 mmol) was added and stirred for 1 hour. Thereafter, decanal (266 mg, 1.7 mmol) was added and the mixture was returned to room temperature, and further stirred for 3 hours. The solution after the reaction was extracted with ether and washed with dilute hydrochloric acid, and then the organic layer was dried over sodium sulfate and the solvent was distilled off. The obtained residue was filtered through silica gel to give 1- (3-chlorobenzo [b] thiophen-2-yl) decan-1-ol (compound I represented by the following formula (I)) as a colorless transparent liquid. (310 mg, 62% yield).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.81-7.76 (m, 2H), 7.46-7.35 (m, 2H), 5.32-5.26 ( m, 1H), 2.23 (d, J = 3.3 Hz, 1H), 2.00-1.80 (m, 2H), 1.55-1.18 (m, 14H), 0.87 ( t, J = 6.9 Hz, 3H)

Synthesis Example 10 Synthesis of 1- (3-chlorobenzo [b] thiophen-2-yl) decan-1-one
In a 20 mL reactor, compound I obtained above dissolved in pyridinium chlorochromate (323 mg, 1.5 mmol), which was previously supported on neutral silica gel (323 mg) using a mortar, and dichloromethane (5 mL). (310 mg, 0.96 mmol) was added, and the mixture was stirred at room temperature for 5 hours. The solution after the reaction was filtered through Celite, and the solvent was distilled off from the obtained filtrate. The residue was filtered through silica gel to give 1- (3-chlorobenzo [b] thiophen-2-yl) decan-1-one (compound J represented by the following formula (J)) as a pink solid (258 mg, yield). 83%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.95 (d, J = 8.0 Hz, 1H), 7.81 (d, J = 7.8 Hz, 1H), 7.54- 7.45 (m, 2H), 3.14 (t, J = 7.5 Hz, 2H), 1.83-1.73 (m, 2H), 1.47-1.20 (m, 12H), 0.88 (t, J = 6.8 Hz, 3H)

(Synthesis Example 11: Synthesis of ethyl 3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophenecarboxylate)
Into a 20 mL reactor, compound J (200 mg, 0.62 mmol) obtained above, ethyl thioglycolate (82.0 mg, 0.68 mmol), potassium carbonate (86.0 mg, 0.62 mmol), and DMF (3 mL) was added and stirred at room temperature for 18 hours. Thereafter, an ethanol solution of sodium hydroxide (0.5 M, 0.4 mL) was added, and the mixture was further stirred for 2 hours. The solution after the reaction was extracted with ether, dried over sodium sulfate, and the solvent was distilled off. The residue is purified by silica gel column chromatography using hexane containing 0.5% by weight of ethyl acetate as a developing solvent, whereby the desired 3-nonylbenzo [4,5] thieno [3,2-b] -2- Ethyl thiophenecarboxylate (Compound K represented by the following formula (K)) was obtained as a yellow solid (220 mg, yield 91%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.89-7.82 (m, 2H), 7.45-7.36 (m, 2H), 4.38 (q, J = 7.3 Hz, 2H), 3.18 (t, J = 7.8 Hz, 2H), 1.80-1.70 (m, 2H), 1.45-1.20 (m, 15H),. 87 (t, J = 6.9 Hz, 3H)

Synthesis Example 12 Synthesis of 3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophene
To a 100 mL eggplant flask, the above-obtained compound K (200 mg, 0.51 mmol), potassium hydroxide (85.8 mg, 1.5 mmol), water (1 mL) and ethanol (4 mL) were added. For 8 hours. Ethanol was distilled off from the solution after the reaction, and after adding diluted hydrochloric acid, the precipitated solid was subjected to suction filtration to give 3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophenecarboxylic acid in white. Obtained as a solid (140 mg, 76% yield).

In a 50 mL eggplant flask, 3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophenecarboxylic acid (300 mg, 0.83 mmol), copper powder (50 mg, 0.83 mmol), and quinoline (5 mL ) And stirred at 260 ° C. for 4 hours under a nitrogen atmosphere. After the reaction, the solution was extracted with ether, the organic layer was dried over sodium sulfate, and the solvent was distilled off. The residue is purified by silica gel column chromatography using hexane as a developing solvent to give 3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophene (represented by the following formula (L)) Compound L) was obtained as an orange liquid (257 mg, yield 98%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.85-7.79 (m, 2H), 7.42-7.28 (m, 2H), 7.08 (s, 1H) , 2.75 (t, J = 7.8 Hz, 2H), 1.82-1.72 (m, 2H), 1.43-1.20 (m, 12H), 0.87 (t, J = 6.9Hz, 3H)

Synthesis Example 13 Synthesis of 2-bromo-3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophene
To the 100 mL eggplant flask, the compound L (80.0 mg, 0.25 mmol) obtained above, NBS (58.0 mg, 0.33 mmol) and DMF (5 mL) were added and stirred at room temperature for 5 hours. After extracting the solution after the reaction with ether, the organic layer was taken out and dried with sodium sulfate, and the solvent was distilled off. The obtained residue was purified by silica gel column chromatography using hexane as a developing solvent. As a result, the desired 2-bromo-3-nonylbenzo [4,5] thieno [3,2-b] -2-thiophene (the following formula: Compound M) represented by (M) was obtained in the state of an orange liquid (93.0 mg, yield 94%).

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.82 (d, J = 8.7 Hz, 1H), 7.74 (d, J = 7.8 Hz, 1H), 7.41− 7.30 (m, 2H), 2.76 (t, J = 7.6 Hz, 2H), 1.78-1.67 (m, 2H), 1.43-1.19 (m, 12H), 0.87 (t, J = 6.6 Hz, 3H)

Synthesis Example 14 Synthesis of 5,5′-bis (3-nonylbenzo [4,5] thieno [3,2-b] -2-thienyl) -2,2′-bithiophene
Into a 20 mL eggplant flask, compound M (130 mg, 0.48 mmol) obtained above, 5,5′-bis (tributylstannyl) -2,2′-bithiophene (100 mg, 0.20 mmol), tetrakis (tri Phenylphosphine) palladium (27.7 mg, 0.024 mmol), DMF (3 mL), and toluene (3 mL) were added, and the mixture was stirred at 85 ° C. for 24 hours. The solution after the reaction was extracted with toluene, and then the organic layer was filtered through silica gel. Toluene was distilled off from the organic layer after filtration, and the residue was washed with acetone and further recrystallized from a mixed solvent of toluene and hexane to obtain the desired 5,5′-bis (3-nonylbenzo [4,5 ] Thieno [3,2-b] -2-thienyl) -2,2′-bithiophene (compound N represented by the following formula (N)) was obtained as an orange solid (44.0 mg, yield 23%). .

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.85 (d, J = 7.8 Hz, 2H), 7.81 (d, J = 7.3 Hz, 2H), 7.43− 7.31 (m, 4H), 7.20 (d, J = 3.6 Hz, 2H), 7.13 (d, J = 3.6 Hz, 2H), 2.98 (t, J = 7.8 Hz) , 4H), 1.86-1.76 (m, 4H), 1.50-1.40 (m, 4H), 1.40-1.20 (m, 20H), 0.86 (t, J = 7.2Hz, 6H)

The ionization potential of Compound N determined by AC-2 was 5.3 eV.

<Example 4>
Synthesis Example 15 Synthesis of 2,5-bis (3-nonylbenzo [4,5] thieno [3,2-b] -2-thienyl) thieno [3,2-b] thiophene
In a 20 mL eggplant flask, compound M (90 mg, 0.21 mmol) obtained in the same manner as in Example 3, 2,5-bis (tributylstannyl) thieno [3,2-b] thiophene (63 mg, 0. 09 mmol), tetrakis (triphenylphosphine) palladium (12.1 mg, 0.011 mmol), DMF (2 mL), and toluene (2 mL) were added, and the mixture was stirred at 85 ° C. for 24 hours. The solution after the reaction was extracted with toluene, and then the organic layer was filtered through silica gel. Toluene was distilled off from the organic layer after filtration, and the residue was washed with acetone and further recrystallized from a mixed solvent of toluene and hexane to obtain the desired 2,5-bis (3-nonylbenzo [4,5]. Thieno [3,2-b] -2-thienyl) thieno [3,2-b] thiophene (Compound O represented by the following formula (O)) was obtained as an orange solid (85.0 mg, yield 46%). It was.

¹ H-NMR measurement results of the obtained target product were as follows.
¹ H-NMR (400 MHz, CDCl ₃ ); δ (ppm) = 7.86 (d, J = 7.8 Hz, 2H), 7.82 (d, J = 7.3 Hz, 2H), 7.45- 7.31 (m, 4H), 7.36 (s, 2H), 2.99 (t, J = 7.8 Hz, 4H), 1.88-1.77 (m, 4H), 1.50- 1.40 (m, 4H), 1.40-1.22 (m, 20H), 0.87 (t, J = 6.9 Hz, 6H)

The ionization potential of Compound O determined by AC-2 was 5.3 eV.

[Characteristic evaluation]
<Example 5>
(Preparation of organic thin film transistor 1 and evaluation of transistor characteristics)
A substrate was prepared in which a silicon oxide film serving as an insulating layer was formed by thermal oxidation on the surface of a heavily doped p-type silicon substrate serving as a gate electrode. This substrate was set on a spin coater, and a β-phenethyltrichlorosilane / toluene (100 μL / 10 mL) solution was dropped and spun to modify the surface of the silicon oxide film.

Compound G synthesized in Example 1 was dissolved in o-dichlorobenzene to prepare a coating solution having a concentration of 0.5% by weight. On the surface-modified substrate, a coating solution was dropped and spun to form an organic thin film containing Compound G. After the obtained organic thin film was annealed in nitrogen at 60 ° C. for 30 minutes, a source electrode and a drain electrode (channel length) made of molybdenum trioxide (15 nm) / Au (50 nm) were formed on the organic thin film by vacuum deposition. / Channel width = 20 μm / 2000 μm) to form an organic thin film transistor 1.

The obtained organic thin film transistor 1 was applied with a gate voltage Vg of 0 to −60 V and a source-drain voltage Vsd of 0 to −60 V in a vacuum, and when the transistor characteristics were measured, a good drain current-gate voltage (Id− Vg) characteristics were obtained. The mobility at this time was 6.8 × 10 ⁻³ cm ² / Vs, the threshold voltage was −16 V, and the on / off ratio was 7 × 10 ⁴ . From this, it was confirmed that the organic thin film transistor 1 using the compound G functions effectively as a p-type organic transistor. Further, the organic thin film transistor 1 operated stably even when it was repeatedly measured.

<Example 6>
(Manufacture of organic thin film transistor 2 and evaluation of transistor characteristics)
An organic thin film transistor 2 was produced in the same manner as in Example 5 except that the compound N synthesized in Example 3 was used in place of the compound G synthesized in Example 1.

When a gate voltage Vg of 0 to −60 V and a source-drain voltage Vsd of 0 to −60 V were applied to the obtained organic thin film transistor 2 in a vacuum, and the transistor characteristics were measured, a good drain current-gate voltage (Id− Vg) characteristics were obtained. The mobility at this time was 6.5 × 10 ⁻³ cm ² / Vs, the threshold voltage was −18 V, and the on / off ratio was 1.5 × 10 ⁵ . From this, it was confirmed that the organic thin film transistor 2 using the compound N effectively functions as a p-type organic transistor. Further, the organic thin film transistor 2 operated stably even when it was repeatedly measured.

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Active layer, 2a ... Active layer, 3 ... Insulating layer, 4 ... Gate electrode, 5 ... Source electrode, 6 ... Drain electrode, 7a ... 1st electrode, 7b ... 2nd electrode, 8 ... Charge generation layer, 100 ... organic thin film transistor according to the first embodiment, 110 ... organic thin film transistor according to the second embodiment, 120 ... organic thin film transistor according to the third embodiment, 130 ... organic thin film transistor according to the fourth embodiment, 140 ... Organic thin film transistor according to fifth embodiment, 150... Organic thin film transistor according to sixth embodiment, 160. Organic thin film transistor according to seventh embodiment, 200... Solar cell according to embodiment, 300. , 310... Optical sensor according to the second embodiment, 320... Optical sensor according to the third embodiment.

Claims (10)

1. An aromatic compound represented by the formula (1).
   

   

   Wherein (1), ^{Ar 11} represents a group forming a conjugated structure with ^{X 11} and ^{X 12} include an aromatic ^{ring, X 11} and ^{X 12} independently formula (1a) or (1b) The group represented by these is shown. In formula (1a) and formula (1b), Ar ¹² and Ar ¹³ each independently represent an aromatic hydrocarbon group having 6 or more carbon atoms, and R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently Represents a hydrogen atom, a halogen atom or a monovalent group, and X ¹³ , X ¹⁴ , X ¹⁵ and X ¹⁶ each independently represent an oxygen atom, a sulfur atom or a selenium atom. ]
2. The aromatic compound according to claim 1, wherein Ar ¹¹ is a group represented by formula (2).
   

   

   [In Formula (2), Ar ²¹ , Ar ²² and Ar ²³ each independently have an aromatic hydrocarbon group having 6 or more carbon atoms which may have a substituent, or have a substituent. A heterocyclic group having 4 or more carbon atoms, wherein m, n and p are each independently an integer of 0 to 6 and m + n + p is an integer of 1 to 10; ]
3. The aromatic compound according to claim 1 or 2, wherein at least one of X ¹³ and X ¹⁴ is a sulfur atom, and at least one of X ¹⁵ and X ¹⁶ is a sulfur atom.
4. The aromatic compound according to any one of claims 1 to 3, wherein Ar ¹² and Ar ¹³ are a phenyl group or a naphthyl group.
5. The aromatic compound according to claim 2, wherein X ¹³ , X ¹⁴ , X ¹⁵ and X ¹⁶ are sulfur atoms, and Ar ¹² and Ar ¹³ are phenyl groups.
6. 6. At least one of Ar ²¹ , Ar ²² and Ar ^{23 is} an optionally substituted thiophene diyl group or an optionally substituted thienothiophene diyl group. The aromatic compound as described in any one.
7. An organic thin film containing the aromatic compound according to any one of claims 1 to 6.
8. An organic thin film element comprising the organic thin film according to claim 7.
9. An organic thin film transistor comprising the organic thin film according to claim 7.
10. An organic photoelectric conversion element comprising the organic thin film according to claim 7.

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