JP2007055939A - Polyacene compound, method for producing the same and organic semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor material developing high mobility, having excellent solubility in a solvent and excellent in oxidation resistance. <P>SOLUTION: The polyacene compound has ≥1 but ≤4 condensed rings in total on an acene ring at the longitudinal direction end of a molecule and has such a structure as represented by chemical formula (I). The condensed ring is formed by connecting, with a coupler such as chemical formula (II), the adjoining two carbon atoms of those of the acene ring formed by bonding R<SB>1</SB>, R<SB>2</SB>, R<SB>3</SB>, R<SB>4</SB>, R<SB>5</SB>, R<SB>6</SB>, R<SB>7</SB>and R<SB>8</SB>in chemical formula (I). In chemical formula (II), A is an aliphatic hydrocarbon group; E is O; and n is ≥1 but ≤5 integer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic semiconductor material and a method for producing the same. The present invention also relates to an organic semiconductor thin film and an organic semiconductor element using the organic semiconductor material.

Devices using organic semiconductors have milder film formation conditions than conventional inorganic semiconductor devices, and it is possible to form semiconductor thin films on various substrates or to form films at room temperature. Costs and flexibility by forming a thin film on a polymer film or the like are expected.
As organic semiconductor materials, conjugated polymer compounds such as polyphenylene vinylene, polypyrrole, and polythiophene, and oligomers thereof, as well as aromatic compounds centering on polyacene compounds such as anthracene, tetracene, and pentacene have been studied. In particular, it has been reported that polyacene compounds have high crystallinity due to their strong intermolecular cohesion, thereby exhibiting high carrier mobility and thereby excellent semiconductor device characteristics.

A polyacene compound is used in a device as a deposited film or a single crystal, and its application to a transistor, a solar cell, a laser, or the like has been studied (see Non-Patent Documents 1 to 3).
In addition, as a method for forming a polyacene compound thin film by a method other than the vapor deposition method, a method of forming a pentacene thin film by applying a solution of a precursor of pentacene, which is a kind of polyacene compound, onto a substrate and heating it has been reported. (See Non-Patent Document 4). In this method, since the polyacene compound has low solubility in a solvent, a thin film is formed using a solution of a highly soluble precursor, and the precursor is converted into a polyacene compound by heat.

On the other hand, polyacene compounds having substituents are reported by Takahashi et al. (Non-Patent Document 5), Graham et al. (Non-Patent Document 6), Anthony et al. (Non-Patent Document 7), and Miller et al. Non-patent document 9 describes a synthesis example of 2,3,9,10-tetramethylpentacene, and non-patent document 10 describes 2,3,9,10-tetrachloro. Examples of synthesis of pentacene are described in Non-Patent Document 11, and examples of synthesis of perfluoropentacene are described.
An organic semiconductor material having a mobility exceeding that of pentacene is not known at present.

“Advanced Materials”, 2002, Vol. 14, p. 99 Jimitrakopouras et al., "Journal of Applied Physics", 1996, Vol. 80, p. 2501 Croke et al., “IEEE Transactions on Electron Devices”, 1999, 46, p. 1258 Brown et al., “Journal of Applied Physics”, 1996, Vol. 79, p. 2136 Takahashi et al., "Journal of American Chemical Society", 2000, Vol. 122, p. 12876 Graham et al., “Journal of Organic Chemistry”, 1995, Volume 60, p. 5770 Anthony et al., “Organic Letters”, 2000, Volume 2, p. 85 Miller et al., “Organic Letters”, 2000, Volume 2, p. 3979 “Advanced Materials”, 2003, Vol. 15, p. 1090 “Journal of American Chemical Society”, 2003, vol. 125, p. 10190 “Journal of American Chemical Society”, 2004, vol. 126, p. 8138

  However, the method of forming a polyacene compound thin film using the precursor as described above has a problem that a high temperature treatment is required to convert the precursor into a polyacene compound (for example, In the case of pentacene, about 150 ° C.). Further, since it is difficult to completely carry out the conversion reaction to the polyacene compound, the unreacted portion remains as a defect, or a modification occurs due to a high temperature, resulting in a defect.

  On the other hand, Takahashi et al.'S report and the like describe derivatives in which substituents are introduced into various polyacene compounds, but do not describe characteristics or thinning as organic semiconductor materials. Further, 2,3,9,10-tetramethylpentacene, 2,3,9,10-tetrachloropentacene and perfluoropentacene are synthesized, but the mobility of each thin film is inferior to that of pentacene. These pentacene derivatives have poor solubility in general organic solvents, and in particular, 2,3,9,10-tetrachloropentacene does not show properties as a semiconductor because modification occurs in the process of forming a thin film at a high temperature.

  Therefore, the present invention solves the problems of the conventional techniques as described above, and provides an organic semiconductor material that exhibits high mobility and is excellent in oxidation resistance and solubility in a solvent, and a method for producing the same. And Another object is to provide an organic semiconductor thin film having high mobility and an organic semiconductor element having excellent electronic characteristics.

  In order to solve the above problems, the present invention has the following configuration. That is, the polyacene compound according to claim 1 of the present invention is a polyacene compound in which a total of 1 to 4 condensed rings are provided on the acene ring at the end of the long axis direction of the molecule. It has a structure represented by I).

However, X in chemical formula (I) is a halogen group or a hydrogen atom, and m is an integer of 1-6. In addition, the fused ring includes two adjacent carbon atoms of the acene ring to which R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ in chemical formula (I) are bonded. , Formed by linking with a linking group such as chemical formula (II), (III), or (IV).

Further, A in the chemical formulas (II) and (IV) represents an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an ester group, an alkyloxycarbonyl group. Group, aryloxycarbonyl group, carboxyl group, formyl group, hydroxyl group, halogen group, amino group, imino group, amide group, cyano group, silyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, hydrogen atom, or these It is a functional group containing two or more groups. Further, E in the chemical formula (II) is CH ₂ , C═O, O, NH, or S, and n is an integer of 1 or more and 5 or less. Furthermore, E ′ in the chemical formula (III) is O or S.

The polyacene compound according to claim 2 of the present invention is characterized in that, in the polyacene compound according to claim 1, the condensed ring is provided only in the acene ring at one end in the longitudinal direction of the molecule.
Furthermore, the polyacene compound according to claim 3 of the present invention is the polyacene compound according to claim 1, wherein the carbon atom of the acene ring to which R ₁ and R ₂ are bonded and the acene ring to which R ₅ and R ₆ are bonded. At least one of the carbon atoms is connected with the linking group to form the condensed ring.

Furthermore, the polyacene compound according to claim 4 of the present invention is the polyacene compound according to claim 1, wherein the carbon atom of the acene ring to which R ₂ and R ₃ are bonded and the acene ring to which R ₆ and R ₇ are bonded At least one of the carbon atoms is connected with the linking group to form the condensed ring.
Furthermore, the polyacene compound according to claim 5 of the present invention is the polyacene compound according to any one of claims 1 to 4, wherein an even number of the plurality of Xs is a halogen group, and at least two halogen atoms are included. It is characterized in that the groups are bound to the same acene ring.

Furthermore, the polyacene compound according to claim 6 of the present invention is the polyacene compound according to any one of claims 1 to 4, wherein two of the plurality of Xs are halogen groups, and these two halogen groups Are bonded to the same acene ring.
Furthermore, the polyacene compound according to claim 7 of the present invention is characterized in that m is 2 or 3 in the polyacene compound according to any one of claims 1 to 4.

Furthermore, the polyacene compound according to claim 8 of the present invention is characterized in that m is 1 in the polyacene compound according to any one of claims 1 to 4.
Furthermore, the manufacturing method of the polyacene compound of Claim 9 which concerns on this invention is a method of manufacturing the polyacene compound as described in any one of Claims 1-8, Comprising: It represents with following Chemical formula (V) A polyacene quinone derivative having such a structure is reduced to a hydroxy polyacene derivative having a structure represented by the following chemical formula (VI), and the hydroxy polyacene derivative is further halogenated and aromatized. .

However, X in chemical formula (V) and chemical formula (VI) is a halogen group or a hydrogen atom, k is an integer of 1 or more, and k + 1 is an integer of 1 or more and 6 or less. The condensed ring is composed of carbon atoms of the acene ring to which R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , and R ₈ in chemical formula (V) and chemical formula (VI) are bonded. Two adjacent ones are formed by linking with a linking group such as chemical formula (VII), (VIII), or (IX).

Further, A in the chemical formulas (VII) and (IX) represents an aliphatic hydrocarbon group such as an alkyl group, alkenyl group, alkynyl group, aryl group, alkoxy group, aryloxy group, acyl group, ester group, alkyloxycarbonyl Group, aryloxycarbonyl group, carboxyl group, formyl group, hydroxyl group, halogen group, amino group, imino group, amide group, cyano group, silyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, hydrogen atom, or these It is a functional group containing two or more groups. Furthermore, E in the chemical formula (VII) is CH ₂ , C═O, O, NH, or S, and n is an integer of 1 or more and 5 or less. Furthermore, E ′ in the chemical formula (VIII) is O or S.

Furthermore, the solution of Claim 10 which concerns on this invention contains the polyacene compound as described in any one of Claims 1-8, It is characterized by the above-mentioned.
Furthermore, the ink of Claim 11 which concerns on this invention contains the polyacene compound as described in any one of Claims 1-8, It is characterized by the above-mentioned.
Furthermore, the organic-semiconductor thin film of Claim 12 which concerns on this invention is comprised with the polyacene compound as described in any one of Claims 1-8, and has crystallinity.

  Furthermore, the organic semiconductor thin film of Claim 13 which concerns on this invention is a crystalline organic semiconductor thin film formed on the board | substrate in the organic semiconductor thin film of Claim 12, Comprising: The long axis of the molecule | numerator of the said polyacene compound Are oriented in a direction perpendicular to the surface of the substrate. Furthermore, an organic semiconductor element according to a fourteenth aspect of the present invention is characterized in that at least a part of the organic semiconductor thin film according to the twelfth or thirteenth aspect is constituted.

Furthermore, the transistor of Claim 15 which concerns on this invention is a transistor provided with a gate electrode, a dielectric material layer, a source electrode, a drain electrode, and a semiconductor layer, The said semiconductor layer is the organic semiconductor of Claim 12 or Claim 13 It is characterized by comprising a thin film.
Furthermore, the display device of claim 16 according to the present invention is a display device comprising a pixel surface comprising a large number of pixels, wherein each pixel comprises the organic semiconductor element according to claim 14 or the transistor according to claim 15. It is characterized by providing.
Furthermore, the display device of claim 17 according to the present invention is the display device of claim 16, wherein the organic semiconductor element or the transistor includes an electrode, a dielectric layer, and a semiconductor layer. It is formed by printing or application | coating of the solution or the ink of Claim 11.

  The polyacene compound of the present invention has a total of 1 or more and 4 or less fused rings in the acene ring at the end (one or both ends) in the long axis direction of the elongated polyacene skeleton, and the side surface portion Has a halogen group or a hydrogen atom. The inventors have improved the solubility in an organic solvent by introducing a condensed ring (cyclic functional group) at the end of the long axis direction of the polyacene compound, and by introducing a halogen group into the side portion, The inventors considered that the oxidation resistance is improved, and have invented a novel polyacene compound having a structure represented by the chemical formula (I).

  And it discovered that the polyacene compound of this invention and its thin film expressed the high mobility which is comparable to or exceeds the pentacene which has the highest mobility in the conventional organic material. Moreover, it discovered that the polyacene compound of this invention was excellent in solubility, and oxidation resistance compared with the pentacene which is poor in the solubility with respect to a solvent at normal temperature. Furthermore, it discovered that the organic-semiconductor element using the thin film of the polyacene compound of this invention showed the outstanding electronic characteristic.

The polyacene compound of the present invention exhibits high mobility and is excellent in solubility in solvents and oxidation resistance. The organic semiconductor thin film of the present invention has high mobility. Furthermore, the organic semiconductor element of the present invention has excellent electronic properties.
Furthermore, the method for producing a polyacene compound of the present invention can easily produce the polyacene compound as described above.

The polyacene compound of the present invention is a compound having a structure as shown in the aforementioned chemical formula (I), and a polyacene having a total of 1 to 4 condensed rings on the acene ring at the end of the molecule in the long axis direction. A compound. When there are a plurality of condensed rings, they may be the same kind of condensed rings, or part or all of them may be heterogeneous condensed rings.
Since such a polyacene compound has a condensed ring (cyclic functional group) at the end in the major axis direction, the solubility in organic solvents is excellent. The cyclic functional group is preferable in that it has less steric influence than the chain functional group, and in particular, n in the chemical formula (II) is 1 or 2 (that is, the condensed ring is a 5-membered or 6-membered ring). Is preferable in that the plane formed by the condensed ring is substantially the same plane as the plane formed by the acene ring.

Of the carbon atoms of the acene ring to which R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ are bonded, those not forming a condensed ring (that is, the linking group) May be bonded to a hydrogen atom, or may be bonded to the same functional group as A in chemical formula (II). That is, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , R ₈ other than the cyclic functional group are the same as the hydrogen atom or the same function as A in the chemical formula (II). It is a group.

Below, the polyacene compound of this invention is demonstrated in detail. E in chemical formula (II) is CH ₂ , C═O, O, NH, or S, but is bonded to the acene ring, and the unshared electron pair of E extends the π-conjugated system of the acene ring. It is expected to increase the orbital overlap between molecules. Therefore, E is more preferably O or S having two sets of unshared electron pairs in the ground state.

  A in chemical formula (II) is an aliphatic hydrocarbon group such as an alkyl group, alkenyl group, alkynyl group, aryl group, alkoxy group, aryloxy group, acyl group, ester group, alkyloxycarbonyl group, aryloxy group. Carbonyl group, carboxyl group, formyl group, hydroxyl group, halogen group, amino group, imino group, amide group, cyano group, silyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, hydrogen atom, or two of these It is a functional group containing the above groups.

  In these, aliphatic hydrocarbon groups, such as an alkyl group, an alkenyl group, an alkynyl group, are preferable, and when the solubility to a solvent and crystallinity are considered, the carbon number has 1-15 preferable. And in order to have high solubility with respect to a solvent, 2-15 carbon atoms are more preferable, and in order to have both high solubility and high crystallinity, it is 2-6 carbon atoms. Particularly preferred. The aliphatic hydrocarbon group may be linear or branched, or may have a cyclic structure.

  Examples of the alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, t-butyl group, n-hexyl group, dodecanyl group, trifluoromethyl group, benzyl group and the like. Examples of alkenyl groups include methacryl and acryl groups, and examples of alkynyl groups include ethynyl and propargyl groups. In the alkenyl group and alkynyl group, the double bond and triple bond may be located at any position in the functional group. Double bonds and triple bonds are for the purpose of strengthening the structure of functional groups, for the purpose of reacting with other molecules using unsaturated bond groups, or for the purpose of reacting (bonding) or polymerizing unsaturated bond groups. Can be used.

  In the functional group other than the aliphatic hydrocarbon group, the carbon number is preferably 1 or more and 15 or less, more preferably 2 or more and 15 or less, as in the case of the aliphatic hydrocarbon group described above. 2 or more and 6 or less is particularly preferable. Examples of the aryloxy group include a phenoxy group, a naphthoxy group, a phenylphenoxy group, and a 4-methylphenoxy group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a 2-methoxyethoxy group, and a t-butoxy group. Can be given. Examples of acyl groups include formyl, acetyl, 2-methylpropanoyl, cyclohexylcarbonyl, octanoyl, 2-hexyldecanoyl, dodecanoyl, chloroacetyl, trifluoroacetyl, and benzoyl. It is done. Examples of the aryloxycarbonyl group include phenoxycarbonyl group, 4-octyloxyphenoxycarbonyl group, 2-hydroxymethylphenoxycarbonyl group, and 4-dodecyloxyphenoxycarbonyl group.

  Examples of the amino group include an amino group, a dimethylamino group, a methylamino group, a methylphenylamino group, and a phenylamino group. Examples of the sulfide group and disulfide group include all groups having a partial structure of “—S—” or “—S—S—”, but may have a cyclic structure. Includes groups containing a thiolane ring, a 1,3-dithiolane ring, a 1,2-dithiolane ring, a thiane ring, a dithiane ring, a thiomorpholine ring, and the like. Such a cyclic structure is preferable in that it has less steric influence than a chain structure.

Furthermore, examples of the silyl group include a trimethylsilyl group, a dimethylphenylsiloxy group, and a diphenylmethylsiloxy group. Examples of the sulfonyl group include a methylsulfonyl group, an n-butylsulfonyl group, an n-octylsulfonyl group, an n-butylsulfonyl group, and a phenylsulfonyl group.
In addition, an acid anhydride structure represented by the chemical formula (III) and an imide structure represented by the chemical formula (IV) are also preferable from the viewpoint of improving the oxidation resistance of the polyacene compound and exhibiting the characteristics of the n-type semiconductor.

  Pentacene compounds that have functional groups on both the long-axis end and side of the polyacene skeleton may interfere with each other (steric hindrance) when stacking molecules, so the conjugation plane overlaps between molecules. May be inhibited. Therefore, it is preferable that the number of functional groups (condensed rings) at the end is smaller. Particularly when the functional group (condensed ring) is present only at one end, the end having the functional group when molecules are stacked together. Are preferable in that they can be arranged in opposite directions. In addition, when a functional group (condensed ring) is present only at one end, polarity is generated in the major axis direction of the molecule, which is preferable in terms of improving solubility in a solvent.

A plurality of X bonded to the side surface portion in the major axis direction of the polyacene skeleton is a halogen group or a hydrogen atom. A part of the plurality of X may be a halogen group and all the others may be a hydrogen atom, a part may be a hydrogen atom, and all the others may be a halogen group. Further, all of the plurality of Xs may be halogen groups, or all may be hydrogen atoms.
The polyacene compound in which an even number of a plurality of X is a halogen group, and two of these halogen groups are bonded to the same acene ring is a polyacene quinone having two carbonyl groups in the same acene ring. It is preferable from the viewpoint that synthesis of (which becomes a precursor in the case of synthesizing a polyacene compound) is easy and that there is little steric hindrance between halogen groups when molecules are stacked. Furthermore, the halogen group in the side surface portion contributes to the improvement of the oxidation resistance of the polyacene compound, but among the halogen groups, a fluorine atom having the smallest van der Waals radius is more preferable.

  In addition, regarding the number of condensed rings of the polyacene skeleton, m in the above-described chemical formula (I) is preferably 2 or 3. In general, as the number of condensed rings increases, the solubility in organic solvents decreases and the reactivity to oxygen, that is, the oxidation resistance decreases. On the other hand, as the number of condensed rings increases, the HOMO-LUMO gap decreases, so that high mobility is expected. Considering these solubility, stability and semiconductor characteristics, pentacene where m is 2 (that is, the number of condensed rings is 5) and hexacene where m is 3 (that is, where the number of condensed rings is 6) are preferable. Further, tetracene where m is 1 (that is, the number of condensed rings is 4) is preferable from the viewpoint of solubility in organic solvents and high stability to oxygen.

Next, a method for synthesizing the polyacene compound of the present invention will be described. The synthesis method of the polyacene compound in the present invention can be roughly classified into two.
(1) Method of converting hydroxyl group of hydroxypolyacene derivative to halogen group (2) Method of converting carbonyl group of polyacenequinone derivative directly to polyacene compound

  The halogen-substituted polyacene compound obtained by the method (1) can be synthesized in two stages using a polyacene quinone compound having a chemical structure corresponding to the polyacene compound as a raw material. In addition, since the polyacene quinone compound has a chemical structure corresponding to the polyacene compound, the number of six-membered rings, the types of functional groups provided, the number, and the substitution position are the same as those of the polyacene compound. Since the compound has a carbonyl group, the ring structure is not a polyacene structure.

  First, the carbonyl group of the polyacene quinone compound is reduced to a hydroxyl group with a metal hydride salt (reducing agent) such as lithium aluminum hydride. When the obtained reduced product (hydroxypolyacene derivative) is reacted with a halogenating agent such as N-chlorosuccinimide in the presence of dimethyl sulfide, halogen substitution and aromatization proceed continuously to obtain a halogen-substituted polyacene derivative. it can.

  That is, a halogen group is introduced into the carbonyl carbon of the polyacene quinone compound to become a halogen-substituted polyacene derivative. One or a plurality of quinone moieties may be used, and a polyhalogen-substituted polyacene derivative can be obtained from a polyacenequinone compound having a plurality of quinone moieties. The hydroxy polyacene derivative has a chemical structure corresponding to that of the polyacene compound, and the number of six-membered rings and the type, number, and substitution position of the functional group provided are the same as those of the polyacene compound. Has a carbon atom bonded to a hydroxyl group and a hydrogen atom, the ring structure is not a polyacene structure.

  For example, a 6,13-dihalogenated pentacene derivative can be synthesized in two steps from a 6,13-pentacenequinone derivative. A 6,13-pentacenequinone derivative having a functional group on the acene ring at both ends in the long axis direction can be easily obtained by a cyclocondensation reaction between a phthalaldehyde derivative and cyclohexane-1,4-dione. On the other hand, a 6,13-pentacenequinone derivative having a functional group only in the acene ring at one end portion in the long axis direction can be easily obtained by a cyclocondensation reaction between a phthalaldehyde derivative and 1,4-dihydroxyanthracene. Regarding phthalaldehyde derivatives, for example, 4,5- (methylenedioxy) -1,2-benzdialdehyde and 3,4- (methylenedioxy) -1,2-benzdialdehyde are known methods or similar methods. Can be easily synthesized.

  The 6,13-pentacenequinone derivative in which the acene ring at both ends in the long axis direction or the acene ring at one end in the long axis direction is substituted with a cyclic functional group is obtained by the above reduction reaction and halogenation-aromatization reaction. It can be converted into a 6,13-dihalogenated pentacene derivative having a functional group at one part or one end. The polyacene compound of the present invention can be synthesized by a method similar to the synthesis method described above, and a desired polyhalogenated polyacene compound can be obtained efficiently.

Moreover, when the reduction reaction using an aluminum trialkoxide etc. is performed with respect to the quinone part of a polyacene quinone compound like the method of above-mentioned (2), it can also convert into a polyacene derivative directly.
The polyacene compound of the present invention can be purified by a conventional purification method such as sublimation and recrystallization after being synthesized by the above-described method, and can be highly purified.

The polyacene compound of the present invention has crystallinity, and this crystal structure is a herringbone type and shows a structure in which molecules are arranged. This herringbone crystal structure has a lattice structure in which elongated molecules are stacked in an arrowhead shape. These crystal structures can be determined by X-ray diffraction using crystals purified and purified as described above.
In addition, the polyacene compound of the present invention exhibits an orthorhombic structure or a cubic structure similarly to the unsubstituted polyacene compound. Here, the lattice constants a, b, and c of the crystal can be determined. The c-axis lattice constant corresponds to the lattice unit length in which the molecular lengths of the elongated molecules are arranged, and the a-axis and b-axis lattice constants are the conjugate planes of the molecules. Corresponds to the size of the lattice unit in the surface of the stacked molecular column.

  Furthermore, the polyacene compound of the present invention has a structure in which the intermolecular distance (corresponding to the a-axis and b-axis lattice constants) where the conjugated surfaces of the molecules are stacked is equivalent or reduced as compared with the unsubstituted polyacene compound. Show. This is because the overlap of π electrons between the molecules is large, and the carriers can easily move between the molecules, which is considered to be a cause of high mobility. Also. The c-axis lattice constant changes corresponding to the molecular length in the major axis direction of the polyacene compound, and is almost equal to or slightly smaller than the molecular length.

  Furthermore, since the polyacene compound of the present invention has a halogen element in the molecular structure, the oxidation resistance is superior to those having no halogen element. This is because the introduction of a halogen element increases the ionization potential of the molecule and decreases the reactivity with oxidizing agents such as oxygen. In addition, introduction of a halogen element also suppresses charge transfer with the electron-accepting molecule, which leads to stability of fluctuation in carrier concentration of the semiconductor. Furthermore, when a field effect transistor is manufactured using the polyacene compound of the present invention, the change in drain current increases with respect to the gate voltage, and a high on / off current ratio is obtained.

Next, the organic semiconductor thin film of the present invention will be described.
As a method for forming the organic semiconductor thin film of the present invention, a known method can be employed. For example, vacuum deposition, MBE (Molecular Beam Epitaxy), sputtering, laser deposition, vapor phase transport growth, etc. Can be given. And by such a method, a thin film can be formed on the substrate surface.

  Since the polyacene compound used in the present invention exhibits sublimation properties, it is possible to form a thin film by the method described above. In the MBE method, the vacuum deposition method, and the vapor transport growth method, a vapor obtained by heating a polyacene compound and sublimating it is transported to the substrate surface at high vacuum, vacuum, low vacuum, or normal pressure to form a thin film. . The sputtering method is a method of forming a thin film by ionizing a polyacene compound in plasma and depositing molecules of the polyacene compound on a substrate. The laser vapor deposition method is a method of forming a thin film by heating a polyacene compound by laser irradiation to generate vapor and depositing polyacene compound molecules on a substrate. Among the above-mentioned production methods, the MBE method, the vacuum evaporation method, and the vapor transport growth method are preferable because they are excellent in flatness and crystallinity of a thin film to be formed.

As a thin film production condition in the MBE method or the vacuum vapor deposition method, for example, the substrate temperature is preferably set to room temperature to 100 ° C. When the substrate temperature is low, an amorphous thin film is likely to be formed, and when the substrate temperature exceeds 100 ° C., the surface smoothness of the thin film decreases. In the case of the vapor transport growth method, the substrate temperature is preferably room temperature or higher and 200 ° C. or lower.
In addition, the polyacene compound of the present invention can easily form a thin film with good crystallinity even when the thin film growth rate is high, and high-speed film formation is possible. The growth rate is preferably in the range of 0.1 nm / min to 1 μm / sec. If it is less than 0.1 nm / min, the crystallinity tends to decrease, and if it exceeds 1 μm / sec, the surface smoothness of the thin film decreases.

  In addition, the organic semiconductor thin film of the present invention can be formed by a wet process. Conventionally known unsubstituted polyacene compounds are hardly soluble in ordinary solvents at room temperature, and it has been difficult to form a thin film by applying a solution and applying a solution. However, the polyacene compound of the present invention can be added to a solvent by introducing a functional group. Since the solubility is equal to or higher than that of the unsubstituted polyacene compound, it is possible to form a solution and form a thin film by applying the solution.

The organic semiconductor thin film of the present invention can be obtained by coating the solution of the polyacene compound of the present invention on a base such as a substrate and evaporating the solvent by a method such as heating. Examples of a method of coating the solution on the base include a method of bringing the base into contact with the solution in addition to coating and spraying. Specific examples include known methods such as spin coating, dip coating, screen printing, ink jet printing, blade coating, printing (lithographic printing, intaglio printing, letterpress printing, etc.). In these printing methods, an ink obtained by adding an additive for adjusting viscosity or the like to the solution of the polyacene compound of the present invention can be used.
Such an operation can be performed in a normal atmosphere or an inert gas atmosphere such as nitrogen or argon. However, since some polyacene compound solutions may be easily oxidized, preparation and storage of the solution and preparation of the organic semiconductor thin film are preferably performed in an inert gas atmosphere.

  Further, when the solvent is vaporized, crystal growth can be controlled by adjusting the solvent vaporization rate at the gas-liquid interface according to the temperature near the base and the solvent vapor pressure of the atmosphere. Furthermore, it is also possible to form an organic semiconductor thin film on the surface of the base in a supersaturated state by bringing the base into contact with a solution of a polyacene compound. Furthermore, if desired, crystal growth can be controlled by applying at least one of a temperature gradient, an electric field, and a magnetic field to the interface between the polyacene compound solution and the base. By these methods, a highly crystalline organic semiconductor thin film can be produced, and the obtained organic semiconductor thin film has high crystallinity and thus has excellent semiconductor characteristics.

Furthermore, the amount of the solvent remaining in the organic semiconductor thin film is preferably low from the viewpoint of the stability and semiconductor characteristics of the organic semiconductor thin film. Therefore, it is usually preferable to remove the solvent remaining in the organic semiconductor thin film almost completely by performing a heat treatment and / or a reduced pressure treatment again after forming the organic semiconductor thin film.
Thus, an organic semiconductor thin film made of a polyacene compound can be formed by a dry process or a wet process.

  As described above, the polyacene compound of the present invention can form a thin film having excellent crystallinity and semiconductor characteristics. In the organic semiconductor thin film of the present invention, the polyacene compound is oriented with the long axis of the molecule perpendicular to the base surface. This is considered to be because the molecular cohesion of the molecules of the polyacene compound is strong, and it is easy to form a molecular column stacked on the molecular surfaces. Therefore, the X-ray diffraction pattern of the organic semiconductor thin film tends to appear with strong (00n) plane strength of the crystal. This inter-plane distance corresponds to the c-axis lattice constant of the crystal.

  Further, in the polyacene compound of the present invention, the intermolecular distance in the a-axis direction and / or the b-axis direction of the crystal axis of the crystal may be reduced, and carrier movement is likely to occur due to the reduction in the intermolecular distance. Show high mobility. An organic semiconductor element composed of such an organic semiconductor thin film is considered to have a property that carriers can easily flow along a molecular column formed in layers. The a-axis and b-axis lattice constants can be observed by oblique incident X-ray diffraction, transmission electron diffraction, a method in which X-rays are incident on the edge of a thin film, and diffraction is measured.

Furthermore, although the normal inorganic semiconductor thin film is affected by the crystallinity and plane orientation of the base material, the organic semiconductor thin film of the present invention is highly crystalline regardless of the crystallinity and plane orientation of the base material. A thin film. Therefore, various materials can be used for the base material regardless of crystallinity or amorphousness.
For example, ceramics such as glass, quartz, aluminum oxide, sapphire, silicon nitride, silicon carbide, semiconductors such as silicon, germanium, gallium arsenide, gallium phosphide, gallium nitrogen, polyester (polyethylene terephthalate, polyethylene naphthalate, etc.), polyethylene, Examples thereof include resins such as polypropylene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, cyclic polyolefin, polyimide, polyamide, polystyrene, polycarbonate, polyether sulfone, polysulfone, and polymethyl methacrylate, paper, and non-woven fabric.

Further, the shape of the base is not particularly limited, but a sheet-like base or a plate-like base (substrate) is usually used.
The organic semiconductor thin film of the present invention is characterized by high carrier mobility, and is preferably 1 × 10 ⁻⁴ cm ² / V · s or more. More preferably, it is 1 × 10 ⁻³ cm ² / V · s or more, and most preferably 1 × 10 ⁻² cm ² / V · s or more.
By using such an organic semiconductor thin film, a semiconductor element useful in fields such as electronics, photonics, and bioelectronics can be manufactured. Examples of such semiconductor elements include diodes, transistors, thin film transistors, memories, photodiodes, light emitting diodes, light emitting transistors, sensors, and the like.

  Transistors and thin film transistors can be used in various display elements such as liquid crystal displays, distributed liquid crystal displays, electrophoretic displays, particle rotating display elements, electrochromic displays, organic light-emitting displays, and electronic paper. Various display devices can be manufactured using the. Transistors and thin film transistors are used in these display elements as switching transistors, signal driver circuit elements, memory circuit elements, signal processing circuit elements, and the like of display pixels.

  When the semiconductor element is a transistor, the element structure includes, for example, a structure of substrate / gate electrode / insulator layer (dielectric layer) / source electrode / drain electrode / semiconductor layer, substrate / semiconductor layer / source electrode. -Structure of drain electrode / insulator layer (dielectric layer) / gate electrode, substrate / source electrode (or drain electrode) / semiconductor layer + insulator layer (dielectric layer) + gate electrode / drain electrode (or source electrode) And the like. At this time, a plurality of source electrodes, drain electrodes, and gate electrodes may be provided. Further, a plurality of semiconductor layers may be provided in the same plane or may be provided in a stacked manner.

  As the structure of the transistor, either a MOS (metal-oxide (insulator layer) -semiconductor) type or a bipolar type can be employed. Since the polyacene compound is usually a p-type semiconductor, an element can be formed by combining with a polyacene compound that is an n-type semiconductor by donor doping or by combining with an n-type semiconductor other than the polyacene compound.

When the semiconductor element is a diode, the element structure includes, for example, a structure of electrode / n-type semiconductor layer / p-type semiconductor layer / electrode. And the organic-semiconductor thin film of this invention is used for a p-type semiconductor layer, and the above-mentioned n-type semiconductor is used for an n-type semiconductor layer.
At least a part of the interface between the organic semiconductor thin film in the semiconductor element or the surface of the organic semiconductor thin film and the electrode can be a Schottky junction and / or a tunnel junction. A semiconductor element having such a junction structure is preferable because a diode or a transistor can be manufactured with a simple structure. Furthermore, a plurality of organic semiconductor elements having such a junction structure can be joined to form elements such as an inverter, an oscillator, a memory, and a sensor.

  Further, when the semiconductor element of the present invention is used as a display element, it can be used as a transistor element (display TFT) that is arranged in each pixel of the display element and switches display of each pixel. Since such an active drive display element does not require patterning of an opposing conductive substrate, depending on the circuit configuration, pixel wiring can be simplified compared to a passive drive display element that does not have a transistor for switching pixels. Usually, one to several switching transistors are arranged per pixel. Such a display element has a structure in which a data line and a gate line which are two-dimensionally formed on a substrate surface cross each other, and the data line and the gate line are respectively joined to the gate electrode, the source electrode and the drain electrode of the transistor. ing. It is possible to divide the data line and the gate line, and to add a current supply line and a signal line.

In addition to the pixel wiring and the transistor, a capacitor can be provided in addition to the pixel of the display element to provide a signal recording function. Furthermore, a display device can be provided by mounting drivers for data lines and gate lines, a memory for pixel signals, a pulse generator, a signal divider, a controller and the like on a substrate on which display elements are formed.
The organic semiconductor element of the present invention can also be used as an arithmetic element and a storage element in an IC card, a smart card, and an electronic tag. In that case, even if these are a contact type or a non-contact type, they can be applied without any problem. The IC card, smart card, and electronic tag are composed of a memory, a pulse generator, a signal divider, a controller, a capacitor, and the like, and may further include an antenna and a battery.

  Furthermore, if the organic semiconductor element of the present invention is configured as a diode, an element having a Schottky junction structure, or an element having a tunnel junction structure, the element can be used as a light receiving element such as a photoelectric conversion element, a solar cell, an infrared sensor, or a photodiode. It can be used as a light emitting element. In addition, when a transistor is constituted by the organic semiconductor element of the present invention, the transistor can be used as a light emitting transistor. A known organic material or inorganic material can be used for the light emitting layer of these light emitting elements.

  Furthermore, the organic semiconductor element of the present invention can be used as a sensor, and can be applied to various sensors such as a gas sensor, a biosensor, a blood sensor, an immune sensor, an artificial retina, and a taste sensor. Usually, the measurement object can be analyzed by a change in the resistance value of the organic semiconductor thin film that occurs when the measurement object is brought into contact with or adjacent to the organic semiconductor thin film constituting the organic semiconductor element.

Hereinafter, the present invention will be described more specifically with reference to examples.
Example 1: Synthesis of 6,13-dichloro-1,2- (methylenedioxy) pentacene
[Method for synthesizing intermediates]
To a solution of 350 mg of 1,2- (methylenedioxy) -6,13-pentacenequinone dissolved in 40 ml of tetrahydrofuran (THF), 15 ml of a THF solution of lithium triethylborate (concentration: 1 mol / 1000 ml) was added, and nitrogen was added. The reaction was allowed to proceed at room temperature for 1 hour in an atmosphere. After neutralizing the resulting solution by adding dilute hydrochloric acid, the organic phase is separated, concentrated, and vacuum-dried to obtain 6,13-dihydro-6,13-dihydroxy-1,2- (methylenedioxy) pentacene. Was obtained almost quantitatively.

[Production method of polyacene compound]
Under a nitrogen atmosphere, 681 mg of N-chlorosuccinimide was dissolved in 10 ml of dichloromethane and cooled to −20 ° C. Then, 0.67 ml of dimethyl sulfide was added dropwise and stirred for 10 minutes. A solution prepared by dissolving 182 mg of 6,13-dihydro-6,13-dihydroxy-1,2- (methylenedioxy) pentacene in 15 ml of THF was added dropwise to the resulting solution. After completion of the addition, the temperature was slowly raised to room temperature. For 18 hours.

  When the reaction was completed by adding water, the reaction product and the like were extracted with chloroform, and the organic phase was washed with saturated brine and then dried over magnesium sulfate. When the organic solvent in the organic phase was distilled off under reduced pressure and the resulting residue was reprecipitated with acetonitrile, pure 6,13-dichloro-1,2,-(methylenedioxy) pentacene (the following chemical formula (X )) 8 mg were obtained. The yield in this reaction was 4%.

The obtained 6,13-dichloro-1,2- (methylenedioxy) pentacene was subjected to mass spectrometry. The results are as follows.
FAB-MS (NBA): m / z = 392, 390
Moreover, nuclear magnetic resonance (NMR) spectrum measurement was performed at room temperature using deuterated chloroform as a solvent. The results are shown below.
¹ H-NMR (ppm): δ 6.30 (s, 2H), 7.33 (d, 1H), 7.41 (dd, 2H), 7.75 (d, 1H), 8.00 (d, 2H), 9.06 (s, 1H), 9.12 (s, 2H), 9.24 (s, 1H)

[Example 2: Synthesis of 2,3- (methylenedioxy) pentacene]
[Production method of polyacene compound]
A mixture of 354 mg of 2,3-methylenedioxy-6,13-pentacenequinone and 6.3 g of aluminum triisopropoxide was heated so that the aluminum triisopropoxide was in a molten state in a nitrogen atmosphere. For 18 hours. After cooling, the mixture was treated with dilute hydrochloric acid, and the product insoluble in the aqueous solution was collected by filtration. The product was then vacuum-dried to obtain a blue-blue solid. This solid was sublimated under a high vacuum of 1.33 × 10 ⁻³ Pa or less to obtain 39 mg of high purity 2,3- (methylenedioxy) pentacene (see the following chemical formula (XI)). The yield in this reaction was 12%.

The obtained 2,3- (methylenedioxy) pentacene was subjected to mass spectrometry. The results are as follows.
FAB-MS (NBA): m / z = 322
Moreover, nuclear magnetic resonance (NMR) spectrum measurement was performed at room temperature using deuterated chloroform as a solvent. The results are shown below.
¹ H-NMR (ppm): δ 6.15 (s, 2H), 7.33 (dd, 2H), 7.72 (s, 2H), 7.94 (dd, 2H), 8.53 (s, 2H), 8.64 (s, 2H), 8.89 (s, 2H)

  The present invention is suitable for electronics, photonics, bioelectronics and the like.

Claims (17)

A polyacene compound having a total of 1 or more and 4 or less condensed rings in the acene ring at the end of the long axis direction of the molecule, having a structure represented by the following chemical formula (I) A polyacene compound.

However, X in chemical formula (I) is a halogen group or a hydrogen atom, and m is an integer of 1-6. In addition, the fused ring includes two adjacent carbon atoms of the acene ring to which R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ in chemical formula (I) are bonded. , Formed by linking with a linking group such as chemical formula (II), (III), or (IV).
Further, A in the chemical formulas (II) and (IV) represents an aliphatic hydrocarbon group such as an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an ester group, an alkyloxycarbonyl group. Group, aryloxycarbonyl group, carboxyl group, formyl group, hydroxyl group, halogen group, amino group, imino group, amide group, cyano group, silyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, hydrogen atom, or these It is a functional group containing two or more groups. Further, E in the chemical formula (II) is CH ₂ , C═O, O, NH, or S, and n is an integer of 1 or more and 5 or less. Furthermore, E ′ in the chemical formula (III) is O or S.   2. The polyacene compound according to claim 1, wherein the condensed ring is provided only in an acene ring at one end of the long axis direction of the molecule. At least _one of the carbon atom of the acene ring to which R ₁ and R ₂ are bonded and the carbon atom of the acene ring to which R ₅ and R ₆ are bonded are connected by the linking group to form the condensed ring. The polyacene compound according to claim 1. At least one of the carbon atom of the acene ring to which R ₂ and R ₃ are bonded and the carbon atom of the acene ring to which R ₆ and R ₇ are bonded are connected by the linking group to form the condensed ring. The polyacene compound according to claim 1.   The polyacene compound according to any one of claims 1 to 4, wherein an even number among the plurality of Xs is a halogen group, and at least two of the halogen groups are bonded to the same acene ring. .   5. The polyacene compound according to claim 1, wherein two of the plurality of X are halogen groups, and the two halogen groups are bonded to the same acene ring.   m is 2 or 3, The polyacene compound as described in any one of Claims 1-4 characterized by the above-mentioned.   m is 1, The polyacene compound as described in any one of Claims 1-4 characterized by the above-mentioned. A method for producing the polyacene compound according to claim 1, wherein a polyacene quinone derivative having a structure represented by the following chemical formula (V) is reduced, and the following chemical formula ( A process for producing a polyacene compound, characterized in that a hydroxypolyacene derivative having a structure represented by VI) is formed, and the hydroxypolyacene derivative is further halogenated and aromatized.

However, X in chemical formula (V) and chemical formula (VI) is a halogen group or a hydrogen atom, k is an integer of 1 or more, and k + 1 is an integer of 1 or more and 6 or less. The condensed ring is composed of carbon atoms of the acene ring to which R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ , and R ₈ in chemical formula (V) and chemical formula (VI) are bonded. Two adjacent ones are formed by linking with a linking group such as chemical formula (VII), (VIII), or (IX).
Further, A in the chemical formulas (VII) and (IX) represents an aliphatic hydrocarbon group such as an alkyl group, alkenyl group, alkynyl group, aryl group, alkoxy group, aryloxy group, acyl group, ester group, alkyloxycarbonyl Group, aryloxycarbonyl group, carboxyl group, formyl group, hydroxyl group, halogen group, amino group, imino group, amide group, cyano group, silyl group, mercapto group, sulfide group, disulfide group, sulfonyl group, hydrogen atom, or these It is a functional group containing two or more groups. Furthermore, E in the chemical formula (VII) is CH ₂ , C═O, O, NH, or S, and n is an integer of 1 or more and 5 or less. Furthermore, E ′ in the chemical formula (VIII) is O or S.   A solution comprising the polyacene compound according to any one of claims 1 to 8.   An ink comprising the polyacene compound according to any one of claims 1 to 8.   An organic semiconductor thin film comprising the polyacene compound according to claim 1 and having crystallinity.   The crystalline organic semiconductor thin film formed on the substrate, wherein the major axis of the molecule of the polyacene compound is oriented in a direction perpendicular to the surface of the substrate. Organic semiconductor thin film.   An organic semiconductor device comprising at least a part of the organic semiconductor thin film according to claim 12 or 13.   14. A transistor comprising a gate electrode, a dielectric layer, a source electrode, a drain electrode, and a semiconductor layer, wherein the semiconductor layer is composed of the organic semiconductor thin film according to claim 12 or 13.   A display device comprising a pixel surface comprising a large number of pixels, wherein each pixel comprises the organic semiconductor element according to claim 14 or the transistor according to claim 15.   The electrode, dielectric layer, and semiconductor layer included in the organic semiconductor element or the transistor are formed by printing or applying the solution according to claim 10 or the ink according to claim 11. The display device according to 1.