JP2007059685A - Organic semiconductor material, organic semiconductor film, organic semiconductor device and organic thin-film transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor film employing an organic semiconductor material having high carrier mobility and sufficient current ON/OFF ratio, and to provide an organic semiconductor device and an organic semiconductor thin-film transistor. <P>SOLUTION: The organic semiconductor material contains a compound represented by a general formula (1). In this case, in the general formula (1), L<SB>1</SB>denotes a bivalent coupling coupled with a conjugated system including an aromatic hydrocarbon ring or an aromatic a heterocycle. Ar<SB>1</SB>-Ar<SB>4</SB>each denote an aromatic a heterocycle. R<SB>1</SB>-R<SB>4</SB>each denote a halogen atom or its substituent, R<SB>5</SB>and R<SB>6</SB>each denote a hydrogen atom, a halogen atom or an aromatic hydrocarbon ring. Ar<SB>1</SB>, Ar<SB>3</SB>and Ar<SB>2</SB>, Ar<SB>4</SB>have a Head-to-Tail structure or a Tail-to-Tail structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic semiconductor material, an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor.

  With the widespread use of information terminals, there is an increasing need for flat panel displays as computer displays. In addition, with the progress of computerization, information that has been provided in paper media has been increasingly digitized, and as a mobile display medium that is thin, light, and portable, electronic paper or digital paper can be used. The need for is increasing.

  In general, in a flat panel display device, a display medium is formed using elements utilizing liquid crystal, organic EL (organic electroluminescence), electrophoresis, or the like. In such display media, a technique using an active drive element (TFT element) as an image drive element has become mainstream in order to ensure uniformity of screen brightness, screen rewrite speed, and the like. For example, in a normal computer display, these TFT elements are formed on a glass substrate, and liquid crystal, organic EL elements, etc. are sealed.

  Here, semiconductors such as a-Si (amorphous silicon) and p-Si (polysilicon) can be mainly used for the TFT element, and these Si semiconductors (and metal films as necessary) are formed into a multilayer structure. The TFT element is manufactured by sequentially forming the drain and gate electrodes on the substrate. The manufacture of such TFT elements usually requires sputtering or other vacuum manufacturing processes.

  However, in the manufacture of such a TFT element, the vacuum system manufacturing process including the vacuum chamber must be repeated many times to form each layer, and the apparatus cost and running cost have become enormous. . For example, in a TFT element, it is usually necessary to repeat the steps of vacuum deposition, dope, photolithography, development, etc. many times for forming each layer, and the element is formed on the substrate through tens of steps. . As for the semiconductor portion that is the key to the switching operation, a plurality of types of semiconductor layers such as p-type and n-type are stacked. In such a conventional manufacturing method using a Si semiconductor, it is not easy to change the equipment, for example, a design change of a manufacturing apparatus such as a vacuum chamber is required in response to the need for a large display screen.

  In addition, since the formation of such a conventional TFT element using a Si material includes a process at a high temperature, the substrate material is restricted to be a material that can withstand the process temperature. Therefore, in practice, glass must be used, and when a thin display such as the electronic paper or digital paper described above is constructed using such a known TFT element, the display is heavy and lacks flexibility. The product may break due to the impact of falling. These characteristics resulting from the formation of TFT elements on a glass substrate are undesirable in satisfying the need for an easy-to-carry-type thin display accompanying the progress of computerization.

  On the other hand, in recent years, organic semiconductor materials have been energetically studied as organic compounds having high charge transport properties. These compounds are reported in numerous papers such as organic laser oscillation elements as discussed in Non-Patent Document 1, etc., and Non-Patent Document 2, for example, in addition to charge transport materials for organic EL elements. Application to organic thin film transistor elements (organic TFT elements) is expected. If these organic semiconductor devices can be realized, there is a possibility of obtaining a semiconductor that can be made into a solution by simplifying the manufacturing process by vacuum or low-pressure deposition at a relatively low temperature and further improving the molecular structure appropriately. It is conceivable that the organic semiconductor solution is made into an ink and manufactured by a printing method including an ink jet method. Manufacturing by these low-temperature processes has been considered impossible for conventional Si-based semiconductor materials, but there is a possibility for devices using organic semiconductors, so the above-mentioned restrictions on substrate heat resistance are relaxed. For example, a TFT element may be formed on the transparent resin substrate. If a TFT element is formed on a transparent resin substrate and the display material can be driven by the TFT element, the display is lighter and more flexible than conventional ones, and will not crack even if dropped (or very difficult to break) It could be a display.

  However, organic semiconductors for realizing such TFT elements have been studied so far as acenes such as pentacene and tetracene (for example, see Patent Document 1), phthalocyanines including lead phthalocyanine, perylene and its tetra. Low molecular weight compounds such as carboxylic acid derivatives (for example, see Patent Document 2), aromatic oligomers typically represented by thiophene hexamers called α-thienyl or sexithiophene (for example, see Patent Document 3), naphthalene, Compounds in which 5-membered aromatic heterocycles are condensed symmetrically to anthracene (for example, see Patent Document 4), mono-, oligo- and polydithienopyridines (for example, see Patent Document 5), polythiophene, polythienylene vinylene, High conjugated content such as poly-p-phenylene vinylene Etc. limited number of compounds (e.g., see Non-Patent Documents 1 to 3.) Is.

  Acenes, which are well known as organic semiconductor materials, for example, condensed with an aromatic hydrocarbon ring represented by the above pentacene, have high intermolecular cohesion and high crystallinity. It has been reported that it exhibits high carrier mobility and excellent semiconductor device characteristics. However, since pentacene is insoluble or hardly soluble in an organic solvent, there is a problem that it is difficult to form a film by coating.

  In addition, thiophene oligomers that do not have a substituent, such as unsubstituted sexual thiophene, also form a π stack between molecules and easily form a regularly arranged structure, but are insoluble or hardly soluble like pentacene. Yes, it is difficult to apply.

  On the other hand, a thiophene oligomer typified by P3HT is soluble in an organic solvent, and can be formed by coating or an inkjet method. However, in a polymer having a molecular weight distribution, formation of a π stack is insufficient, and there are many portions where the molecular arrangement is disturbed, so that satisfactory carrier mobility and ON / OFF ratio cannot be obtained.

In addition, by arranging side-chains arranged in a regioregular manner on the polythiophene main chain, the arrangement of molecules is promoted to form a densely stacked lamella structure, and TFT elements fabricated by the coating process are introduced. However, satisfactory mobility is not obtained, and a material with higher mobility is desired.
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A JP 2003-264655 A JP 2003-264327 A JP 2003-268083 A “Science” 289, 599 (2000) “Nature”, 403, 521 (2000) Advanced Material, 2002, No. 2, page 99

  An object of the present invention is to provide an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor using an organic semiconductor material having a high carrier mobility and a sufficient current ON / OFF ratio.

  The above object of the present invention is achieved by the following configurations.

  (1) An organic semiconductor material comprising a compound represented by the following general formula (1).

(In General Formula (1), L ₁ represents a divalent linking group bonded with a conjugated system including an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar _{1 to} Ar ₄ represent an aromatic heterocyclic ring. _{1 to} R ₄ each represents a halogen atom or a substituent, and R ₅ and R ₆ each represent a hydrogen atom, a halogen atom or a substituent, provided that Ar ₁ , Ar ₃ and Ar ₂ , Ar ₄ represent Head-to-Tail. Structure or tail-to-tail structure)
(2) The organic semiconductor material as described in (1) above, wherein the molecular weight of the compound represented by the general formula (1) is 10,000 or less.

(3) The organic semiconductor material according to (1) or (2), wherein Ar _{1 to} Ar ₄ in the general formula (1) are a thiophene ring and a thiazole ring, or all are thiophene rings.

  (4) The organic semiconductor material according to (3), wherein the thiophene ring and the thiazole ring in the general formula (1), or the total number of all thiophene rings is 5 to 40, respectively.

  (5) The organic semiconductor material according to (1) or (2), wherein the general formula (1) has a partial structure represented by the following general formula (2) or (3).

(In general formulas (2) and (3), Ar _{5 to} Ar ₈ represent a 5-membered aromatic heterocyclic ring, and R ₇ and R ₈ represent a halogen atom or a substituent.)
(6) The organic semiconductor material as described in (5) above, wherein Ar _{5 to} Ar ₈ in the general formula (2) or (3) are a thiophene ring and a thiazole ring, or all are thiophene rings.

  (7) The organic semiconductor according to (1) or (2), wherein the compound represented by the general formula (1) is represented by any one of the following general formulas (4a) to (4d): material.

(In the general formulas (4a) to (4d), L ₁ represents a divalent linking group bonded with a conjugated system containing an aromatic hydrocarbon ring or an aromatic heterocycle, and R _{1 to} R ₄ represent a halogen atom or a substituent. R ₅ and R ₆ represent a hydrogen atom, a halogen atom or a substituent, A _{1 to} A ₁₂ represent a carbon atom, a nitrogen atom, a sulfur atom or an oxygen atom, provided that A _{1 to} A ₃ , A ₄ ~A _6, 5-membered ring formed by each of _{a 7 ~A 9, a 10 ~A} 12 are all aromatic heterocyclic ring.)
(8) The 5-membered aromatic heterocycle formed by each of A _{1 to} A ₃ , A _{4 to} A ₆ , A _{7 to} A ₉ , and A _{10 to} A _{12 in} the general formulas (4a) to (4d) The organic semiconductor material as described in (7) above, wherein the thiophene ring and thiazole ring, or all are thiophene rings.

  (9) The organic semiconductor according to (8) above, wherein the total number of thiophene rings and thiazole rings in the general formulas (4a) to (4d), or all thiophene rings in each of the thiophene rings is 5 to 40 material.

  (10) The organic semiconductor material as described in (8) above, wherein the general formula (4a) has a partial structure represented by the general formula (2).

(11) The organic semiconductor material as described in (10) above, wherein Ar _{5 to} Ar ₈ in the general formula (2) are a thiophene ring and a thiazole ring, or all are thiophene rings.

  (12) The organic semiconductor material as described in (8) above, wherein the general formula (4b) has a partial structure represented by the general formula (3).

(13) The organic semiconductor material as described in (12) above, wherein Ar _{5 to} Ar ₈ in the general formula (3) are a thiophene ring and a thiazole ring, or all are thiophene rings.

  (14) An organic semiconductor material having no head-to-head structure in the structure of the organic semiconductor material according to any one of (1) to (13).

  (15) An organic semiconductor film comprising the organic semiconductor material according to any one of (1) to (14).

  (16) An organic semiconductor device using the organic semiconductor material according to any one of (1) to (14).

  (17) An organic thin film transistor, wherein the organic semiconductor material according to any one of (1) to (14) is used for a semiconductor layer.

  According to the present invention, an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor using an organic semiconductor material having high carrier mobility and a sufficient current ON / OFF ratio can be provided.

In the compound represented by the general formula (1) according to the present invention, Ar ₁ , Ar ₃ and Ar ₂ , Ar ₄ have a head-to-tail structure or a tail-to-tail structure. There is no head-to-head structure in the structure. Here, the head-to-tail structure, the tail-to-tail structure, and the head-to-head structure are those having a substituent in the positional relationship shown below.

  When the compound has a head-to-head structure in the structure, the aromatic rings linked due to the steric hindrance of the tauto substituents are shifted from each other in the same plane and twisted at an angle. Such a twisted structure prevents a carrier charge in the main chain from delocalizing, and limits the effective conjugate length for carrier movement.

  When the head-to-tail structure or the tail-to-tail structure is used, the above twisted structure does not occur, and the π plane of the aromatic ring in the main chain can exist on the same plane. A π conjugate plane is formed. Such a large π-conjugated surface further promotes the π stack between molecules. Further, by adopting a head-to-tail structure or a tail-to-tail structure, a thin film in which side chains are regularly arranged between molecules and formation of a lamellar structure is more effectively promoted, and molecules are densely arranged. Can be formed. Such an effect is particularly significant when only one of a head-to-tail structure or a tail-to-tail structure is present in the molecule. Moreover, sufficient solubility required for the coating method (also referred to as a solution process) can be obtained by introducing a substituent. As described above, by using the organic semiconductor material of the present invention, an organic thin film transistor having high mobility and which can be easily manufactured by a coating method can be provided.

In the general formula (1), L ₁ represents a divalent linking group bonded with a conjugated system including an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar _{1 to} Ar ₄ represent an aromatic heterocyclic ring. R _{1 to} R ₄ represent a halogen atom or a substituent, and R ₅ and R ₆ represent a hydrogen atom, a halogen atom or a substituent.

  As the aromatic hydrocarbon ring, benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, Examples thereof include a p-terphenyl ring, an acenaphthene ring, a coronene ring, a fluorene ring, a fluoranthrene ring, a naphthacene ring, a pentacene ring, a perylene ring, a pentaphen ring, a picene ring, a pyrene ring, a pyranthrene ring, and an anthrathrene ring. Of these, a benzene ring is preferably used. Further, these aromatic hydrocarbon rings may be unsubstituted or may have a substituent. Examples of the substituent include an aromatic hydrocarbon ring in which two or more rings are condensed and two or more rings. And the substituents described as the substituents of the aromatic heterocyclic ring condensed with.

  Aromatic heterocycles include furan ring, thiophene ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole At least one of the carbon atoms of the hydrocarbon ring constituting the ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, carboline ring is further substituted with a nitrogen atom Ring and the like.

Examples of the substituent represented by R _{1 to} R ₄ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group). Group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aryl group ( For example, phenyl group, naphthyl group, etc.), aromatic heterocycle (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, Phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imi Zolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, Cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group) Etc.), a cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyl) Ruoxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, Methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group Etc.), an acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octyl group) Rucarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group) Group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2 -Ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), Rubamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group) , Phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido) Group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfuric group) Sulfonyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group) Cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc., arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group etc.), amino group (for example, amino group, ethylamino group, dimethyl) Amino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), fluorinated hydrocarbon Group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxyl group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, Triphenylsilyl group, phenyldiethylsilyl group, etc.). Of these substituents, an alkyl group is preferable.

As the substituent represented by R ₅ and R ₆ , those exemplified above for the substituent represented by R _{1 to} R ₄ can be applied. Among these substituents, an aromatic hydrocarbon ring or an aromatic heterocyclic ring is preferable, and an aromatic hydrocarbon ring is more preferable.

In the general formulas (2) and (3), Ar _{5 to} Ar ₈ represent a 5-membered aromatic heterocyclic ring, and R ₇ and R ₈ represent a halogen atom or a substituent. Examples of the 5-membered aromatic heterocycle include a furan ring, a thiophene ring, a triazole ring, an imidazole ring, a pyrazole ring, a thiazole ring, an isothiazole ring, a xazole ring, and an isoxazole ring. Examples of the substituent represented by R ₇ and R ₈ include the same ones as the substituents represented by R _{1 to} R ₄ above, and an alkyl group is preferable.

In the general formulas (4a) to (4d), L ₁ represents a divalent linking group bonded with a conjugated system including an aromatic hydrocarbon ring or an aromatic heterocyclic ring, and R _{1 to} R ₄ represent a halogen atom or a substituent. R ₅ and R ₆ each represents a hydrogen atom, a halogen atom or an aromatic hydrocarbon ring. A _{1 to} A ₁₂ represent a carbon atom, a nitrogen atom, a sulfur atom, or an oxygen atom. However, the 5-membered rings formed by A _{1 to} A ₃ , A _{4 to} A ₆ , A _{7 to} A ₉ , and A _{10 to} A ₁₂ are all aromatic heterocycles.

L ₁ , R _{1 to} R ₄ , R ₅ and R ₆ have the same meanings as those in the general formula (1), and A _{1 to} A ₃ , A _{4 to} A ₆ , A _{7 to} A ₉ , A _{10 to} A ₁₂ The 5-membered aromatic heterocycle formed by each has the same meaning as the aromatic heterocycle represented by Ar _{5 to} Ar ₈ in the general formulas (2) and (3).

  Hereinafter, although the specific exemplary compound of the compound represented by the said General formula (1) based on this invention is shown, it is not limited to these.

  The compounds according to the present invention represented by compound examples are described in, for example, J. Org. Mater. Chem. , 11, 5, 1357-1363 (2001).

<Organic semiconductor film>
The organic semiconductor film of the present invention will be described.

  The organic semiconductor material of the present invention can be mixed with an appropriate organic solvent (described later) and used as a solution or dispersion.

  When producing an organic semiconductor film using a solution containing the organic semiconductor material of the present invention, any organic solvent may be used, or two or more organic solvents may be mixed and used. Preferably, it contains at least one non-halogen solvent, and more preferably only non-halogen solvent.

<< Solution or dispersion at room temperature >>
The organic semiconductor film of the present invention is preferably produced through a step of forming a film using a solution or a dispersion at room temperature, prepared by mixing the organic semiconductor material of the present invention with the organic solvent shown below. Here, the solution or dispersion at room temperature preferably forms a solution or dispersion when the organic semiconductor material and the organic solvent are mixed at 10 to 80 ° C. The dispersion is an organic semiconductor material. Represents a state in which the organic semiconductor material is partially dissolved in the dispersion liquid.

  Further, as one aspect of the dispersion, for example, it dissolves under a temperature condition of 80 ° C. to form a solution, but when returned to room temperature (usually showing a temperature of about 25 ° C.), particles, aggregates of organic semiconductor material, The state etc. in which the precipitate etc. are disperse | distributed in the organic solvent can be mentioned.

(Organic solvent)
There is no restriction | limiting in particular as an organic solvent used for preparation of said solution or dispersion liquid, Although a single solvent or a mixed solvent may be sufficient, Preferably a non-halogen-type solvent is used. Non-halogen solvents used in the present invention include aliphatic solvents such as hexane and octane, alicyclic solvents such as cyclohexane, aromatic solvents such as benzene, toluene and xylene, tetrahydrofuran, dioxane, and ethylene glycol diethyl ether. , Ether solvents such as anisole, benzyl ethyl ether, ethyl phenyl ether, diphenyl ether, and methyl-t-butyl ether, ester solvents such as methyl acetate, ethyl acetate, and ethyl cellosolve, alcohol solvents such as methanol, ethanol, and isopropanol, acetone , Ketone solvents such as methyl ethyl ketone, cyclohexanone, 2-hexanone, 2-heptanone and 3-heptanone, other dimethylformamide, dimethylsulfoxide, diethylformamide, 1,3- Oxolane, and the like.

  Further, the organic solvent used in combination is not particularly limited, but preferred ones are methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, pyrrolidone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl acetate. , Ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, methyl β-methoxypropionate, ethyl β-ethoxypropionate, propylene glycol monomethyl ether acetate, toluene, xylene, hexane, limonene, cyclohexane and the like. Two or more of these organic solvents can be used in combination.

  In addition, oxyisobutyric acid alkyl ester or the like may be used as an ester solvent, and oxyisobutyric acid ester may be α such as methyl α-methoxyisobutyrate, ethyl α-methoxyisobutyrate, methyl α-ethoxyisobutyrate, or ethyl α-ethoxyisobutyrate. -Alkoxyisobutyric acid alkyl esters; β-alkoxyisobutyric acid alkyl esters such as methyl β-methoxyisobutyrate, ethyl β-methoxyisobutyrate, methyl β-ethoxyisobutyrate, ethyl β-ethoxyisobutyrate; and methyl α-hydroxyisobutyrate, α- Examples include α-hydroxyisobutyric acid alkyl esters such as ethyl hydroxyisobutyrate, and in particular, methyl α-methoxyisobutyrate, methyl β-methoxyisobutyrate, methyl β-ethoxyisobutyrate or methyl α-hydroxyisobutyrate can be used. The

<< Organic semiconductor device, organic thin film transistor (also called organic TFT) >>
The organic semiconductor device and organic thin film transistor (also referred to as organic TFT in the present application) of the present invention will be described.

  The organic semiconductor material of the present invention can be used for a semiconductor layer such as an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor (organic TFT), thereby providing an organic semiconductor device and an organic TFT that are driven well.

  An organic TFT (organic thin-film transistor) has a source electrode and a drain electrode connected by a semiconductor semiconductor channel as a semiconductor layer on a support, and a top gate type having a gate electrode on the gate electrode via a gate insulating layer. First, it is roughly classified into a bottom gate type having a gate electrode on a body and having a source electrode and a drain electrode connected by an organic semiconductor channel through a gate insulating layer.

  In order to install the organic semiconductor material of the present invention on a semiconductor layer of an organic semiconductor film, an organic semiconductor device, or an organic thin film transistor, it can be installed on a substrate by vacuum deposition, but it can be dissolved in an appropriate solvent and added as necessary. It is preferable to place the solution prepared by adding the solution on the substrate by cast coating, spin coating, printing, inkjet method, ablation method or the like.

  In this case, the solvent for dissolving the organic semiconductor material of the present invention is not particularly limited as long as the organic semiconductor material can be dissolved to prepare a solution having an appropriate concentration, but specifically, diethyl ether or diisopropyl ether. Linear ether solvents such as tetrahydrofuran and dioxane, ketone solvents such as acetone and methyl ethyl ketone, alkyl halide solvents such as chloroform and 1,2-dichloroethane, toluene, o-dichlorobenzene, nitrobenzene And aromatic solvents such as m-cresol, aliphatic hydrocarbon solvents such as N-methylpyrrolidone, carbon disulfide and n-hexane, and cyclic hydrocarbon solvents such as cyclohexane. Of these solvents, a solvent containing a non-halogen solvent is preferable, and a non-halogen solvent is preferable.

  In the organic thin film transistor of the present invention, the organic semiconductor material of the present invention is preferably used for the semiconductor layer as described above. The semiconductor layer is preferably formed by applying a solution or dispersion containing these organic semiconductor materials. The solvent for dissolving the organic semiconductor material is preferably a solvent containing the non-halogen solvent, and is preferably composed of a non-halogen solvent.

  In the present invention, the material for forming the source electrode, the drain electrode and the gate electrode is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium , Palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin oxide / antimony, indium tin oxide (ITO), fluorine doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste and carbon Paste, lithium, beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium / Copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, lithium / aluminum mixture, etc., especially platinum, gold, silver, copper, aluminum, indium, ITO And carbon are preferred. Alternatively, a known conductive polymer whose conductivity is improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylenedioxythiophene and polystyrenesulfonic acid, or the like is also preferably used. Among them, those having low electrical resistance at the contact surface with the semiconductor layer are preferable.

  As a method for forming an electrode, a method for forming an electrode using a known photolithographic method or a lift-off method from a conductive thin film formed using a method such as vapor deposition or sputtering using the above as a raw material, or a metal foil such as aluminum or copper There is a method of etching using a resist by thermal transfer, ink jet or the like. Alternatively, a conductive polymer solution or dispersion, or a conductive fine particle dispersion may be directly patterned by ink jetting, or may be formed from a coating film by lithography, laser ablation, or the like. Furthermore, a method of patterning an ink containing a conductive polymer or conductive fine particles, a conductive paste, or the like by a printing method such as relief printing, intaglio printing, planographic printing, or screen printing can also be used.

  Various insulating films can be used as the gate insulating layer, and an inorganic oxide film having a high relative dielectric constant is particularly preferable. Inorganic oxides include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, Examples thereof include barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, and trioxide yttrium. Of these, silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide are preferable. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.

  Examples of the method for forming the film include a vacuum process, a molecular beam epitaxial growth method, an ion cluster beam method, a low energy ion beam method, an ion plating method, a CVD method, a sputtering method, an atmospheric pressure plasma method, and the like, spraying Examples include a wet process such as a coating method, a spin coating method, a blade coating method, a dip coating method, a casting method, a roll coating method, a bar coating method, a coating method such as a die coating method, and a patterning method such as printing or inkjet. Can be used depending on the material.

  The wet process is a method of applying and drying a liquid in which fine particles of inorganic oxide are dispersed in an arbitrary organic solvent or water using a dispersion aid such as a surfactant as required, or an oxide precursor, for example, A so-called sol-gel method in which a solution of an alkoxide body is applied and dried is used. Among these, the atmospheric pressure plasma method and the sol-gel method are preferable.

  The method for forming an insulating film by plasma film formation under atmospheric pressure is a process in which a reactive gas is discharged under atmospheric pressure or a pressure near atmospheric pressure to excite reactive gas to form a thin film on a substrate. The method is described in JP-A-11-61406, JP-A-11-133205, JP-A-2000-121804, JP-A-2000-147209, and JP-A-2000-185362. Accordingly, a highly functional thin film can be formed with high productivity.

  In addition, as an organic compound film, polyimide, polyamide, polyester, polyacrylate, photo-curing polymer of photo radical polymerization system, photo cation polymerization system, or copolymer containing acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolac resin, and Cyanoethyl pullulan or the like can also be used. As the method for forming the organic compound film, the wet process is preferable. An inorganic oxide film and an organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.

  Moreover, a support body is comprised with glass or a flexible resin-made sheet | seat, for example, a plastic film can be used as a sheet | seat. Examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC). And a film made of cellulose triacetate (TAC), cellulose acetate propionate (CAP), or the like. Thus, by using a plastic film, the weight can be reduced as compared with the case of using a glass substrate, the portability can be improved, and the resistance to impact can be improved.

  Below, the organic thin-film transistor using the organic-semiconductor film formed using the organic-semiconductor material of this invention is demonstrated.

  FIG. 1 is a diagram showing a configuration example of an organic thin film transistor of the present invention. In FIG. 2A, a source electrode 2 and a drain electrode 3 are formed on a support 6 by a metal foil or the like, an organic semiconductor layer 1 made of the organic semiconductor material of the present invention is formed between both electrodes, and insulation is formed thereon. The layer 5 is formed, and the gate electrode 4 is further formed thereon to form an organic thin film transistor. FIG. 2B shows the organic semiconductor layer 1 formed between the electrodes in FIG. 1A so as to cover the entire surface of the electrode and the support using a coating method or the like. (C) shows that the organic semiconductor layer 1 is first formed on the support 6 by using a coating method or the like, and then the source electrode 2, the drain electrode 3, the insulating layer 5, and the gate electrode 4 are formed.

  In FIG. 4D, after forming the gate electrode 4 on the support 6 with a metal foil or the like, the insulating layer 5 is formed thereon, and the source electrode 2 and the drain electrode 3 are formed on the metal foil or the like. An organic semiconductor layer 1 formed of the organic semiconductor material of the present invention is formed between the electrodes. In addition, the configuration as shown in FIGS.

  FIG. 2 is a diagram showing an example of a schematic equivalent circuit diagram of an organic thin film transistor sheet.

  The organic thin film transistor sheet 10 has a large number of organic thin film transistors 11 arranged in a matrix. 7 is a gate bus line of each organic thin film transistor 11, and 8 is a source bus line of each organic thin film transistor 11. An output element 12 is connected to the source electrode of each organic thin film transistor 11, and the output 12 is, for example, a liquid crystal, an electrophoretic element, or the like, and constitutes a pixel in the display device. The pixel electrode may be used as an input electrode of the photosensor. In the illustrated example, a liquid crystal as an output element is shown by an equivalent circuit composed of a resistor and a capacitor. 13 is a storage capacitor, 14 is a vertical drive circuit, and 15 is a horizontal drive circuit.

<< Organic EL element (Organic electroluminescence element) >>
The organic semiconductor device or the organic thin film transistor of the present invention can be provided in an organic electroluminescence element (also referred to as an organic EL element), and the organic EL element according to the present invention includes, for example, an organic EL layer between an anode and a cathode. Although the thing of the state in which (it is also mentioned an organic compound layer) is pinched | listed is mentioned, as these structures, it can produce using a conventionally well-known layer structure, the material of an organic EL layer, etc. For example, references such as Nature, 395, 151-154 can be referred to. The organic thin film transistor using the organic semiconductor material of the present invention can be applied to the technology introduced in, for example, SID 2005, sessions 49-1, 2 and 3, and an a-Si transistor is used as the organic semiconductor transistor of the present invention. It is possible to obtain good characteristics by replacing with.

  The organic semiconductor device of the present invention is used from the viewpoint of obtaining high light emission luminance and a long light emission lifetime when the organic EL element according to the present invention emits light (for example, applied to a display device, a lighting device, etc.). Or it is preferable to comprise the organic thin-film transistor of this invention.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
<< Production of Organic Thin Film Transistor 1 >>
A 200 nm thick thermal oxide film was formed on a Si wafer having a specific resistance of 0.02 Ω · cm as a gate electrode to form a gate insulating layer, and then surface treatment with octadecyltrichlorosilane was performed.

Next, a cyclohexane solution of the comparative compound (1) is bubbled with nitrogen gas as an organic semiconductor to remove dissolved oxygen in the solution, and the thermal oxide film (oxidation) is performed in a nitrogen gas atmosphere of 1.013 × 10 ² kPa. The cast film (thickness 20 nm) was formed by applying an applicator on the surface of the silicon film. After drying at room temperature, heat treatment was performed in an N ₂ gas atmosphere.

  Further, gold was deposited on the surface of this film using a mask to form a source electrode and a drain electrode. Thus, an organic thin film transistor 1 (comparative example) having a channel length L = 30 μm and a channel width W = 1 mm was produced.

<< Production of Organic Thin Film Transistors 2 and 3 >>
In the preparation of the organic thin film transistor 1, the comparative compound (1) was changed to the comparative compound (2) (synthesized with reference to JACS, 126, 3378-3379 (2004)) and the comparative compound (3), and a solution or dispersion of chloroform. Organic thin-film transistors 2 and 3 (comparative examples) were produced in the same manner as the organic thin-film transistor 1 except that they were used as liquids.

<< Production of Organic Thin Film Transistors 4-8 >>
In the production of the organic thin film transistor 1, organic thin film transistors 4 to 8 (the present invention) were produced in the same manner except that the organic semiconductor material of the present invention described in Table 1 was used as an alternative to the comparative compound (1).

<< Evaluation of carrier mobility and ON / OFF ratio >>
About each of the obtained organic thin-film transistors 1-8, the carrier mobility and ON / OFF ratio of each element immediately after preparation were calculated | required, respectively. In the present invention, the carrier mobility is obtained from the saturation region of the IV characteristic, and the ON / OFF ratio is obtained from the ratio of the drain current value when the drain bias is −50 V and the gate bias is −50 V and 0 V.

  The obtained results are shown in Table 1.

  From Table 1, it can be seen that the organic TFT elements 4 to 8 of the present invention exhibit excellent transistor characteristics while having sufficient solubility as compared with the comparative organic TFT element.

Example 2
<< Production of organic EL element >>
The organic EL element was produced by referring to the method described in Nature, 395, 151-154, to produce a top emission type organic EL element having a sealing structure as shown in FIG. 3, 101 denotes a substrate, 102a denotes an anode, 102b denotes an organic EL layer (specifically, an electron transport layer, a light emitting layer, a hole transport layer, and the like), 102c denotes a cathode, and the anode 102a The light emitting element 102 is formed by the organic EL layer 102b and the cathode 102c. Reference numeral 103 denotes a sealing film. The organic EL element according to the present invention may be either a bottom emission type or a top emission type.

  The organic EL element according to the present invention and the organic thin film transistor of the present invention (herein, the organic thin film transistor of the present invention is used as a switching transistor, a driving transistor, etc.) were combined to produce an active matrix light emitting element. In this case, for example, an embodiment using a substrate in which a TFT 602 (or an organic thin film transistor 602 may be formed) is formed on a glass substrate 601 as shown in FIG. Here, a known TFT manufacturing method can be referred to for the TFT 602 manufacturing method. Of course, the TFT may be a conventionally known top gate type TFT or bottom gate type TFT.

  The organic EL device produced above showed good light emission characteristics in various light emission forms such as single color, full color, and white.

It is a figure which shows the structural example of the organic thin-film transistor of this invention. It is an example of the schematic equivalent circuit schematic of the organic thin-film transistor sheet of this invention. It is a schematic diagram which shows an example of the organic EL element which has a sealing structure. It is a schematic diagram which shows an example of the board | substrate which has TFT used for an organic EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic-semiconductor layer 2 Source electrode 3 Drain electrode 4 Gate electrode 5 Insulating layer 6 Support body 7 Gate bus line 8 Source bus line 10 Organic thin-film transistor sheet 11 Organic thin-film transistor 12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit 102 Organic EL element 102a, 202 Anode 102b Organic EL layer 102c, 204 Cathode 103 Sealing film 205 Drive element 206 Hole transport layer 207 Light emitting layer 208 Electron transport layer 601 Substrate 602 TFT thin film transistor

Claims (17)

An organic semiconductor material comprising a compound represented by the following general formula (1):

(In General Formula (1), L ₁ represents a divalent linking group bonded with a conjugated system including an aromatic hydrocarbon ring or an aromatic heterocyclic ring. Ar _{1 to} Ar ₄ represent an aromatic heterocyclic ring. _{1 to} R ₄ each represents a halogen atom or a substituent, and R ₅ and R ₆ each represent a hydrogen atom, a halogen atom or a substituent, provided that Ar ₁ , Ar ₃ and Ar ₂ , Ar ₄ represent Head-to-Tail. Structure or tail-to-tail structure) The organic semiconductor material according to claim 1, wherein the compound represented by the general formula (1) has a molecular weight of 10,000 or less. The organic semiconductor material according to claim 1, wherein Ar _{1 to} Ar ₄ in the general formula (1) are a thiophene ring and a thiazole ring, or all are thiophene rings. 4. The organic semiconductor material according to claim 3, wherein the total number of rings in the thiophene ring and the thiazole ring in the general formula (1) or all in each thiophene ring is 5 to 40. 5. The organic semiconductor material according to claim 1 or 2, wherein the general formula (1) has a partial structure represented by the following general formula (2) or (3).

(In general formulas (2) and (3), Ar _{5 to} Ar ₈ represent a 5-membered aromatic heterocyclic ring, and R ₇ and R ₈ represent a halogen atom or a substituent.) The organic semiconductor material according to claim 5, wherein Ar _{5 to} Ar ₈ in the general formula (2) or (3) are a thiophene ring and a thiazole ring, or all are thiophene rings. The organic semiconductor material according to claim 1 or 2, wherein the compound represented by the general formula (1) is represented by any one of the following general formulas (4a) to (4d).

(In the general formulas (4a) to (4d), L ₁ represents a divalent linking group bonded with a conjugated system containing an aromatic hydrocarbon ring or an aromatic heterocycle, and R _{1 to} R ₄ represent a halogen atom or a substituent. R ₅ and R ₆ represent a hydrogen atom, a halogen atom or a substituent, A _{1 to} A ₁₂ represent a carbon atom, a nitrogen atom, a sulfur atom or an oxygen atom, provided that A _{1 to} A ₃ , A ₄ to a _6, 5-membered ring formed by each of _{a 7 ~A 9, a 10 ~A} 12 are all aromatic heterocyclic ring.) In the general formulas (4a) to (4d), a 5-membered aromatic heterocycle formed by each of A _{1 to} A ₃ , A _{4 to} A ₆ , A _{7 to} A ₉ , and A _{10 to} A ₁₂ is a thiophene ring and The organic semiconductor material according to claim 7, wherein the thiazole ring or all are thiophene rings. 9. The organic semiconductor material according to claim 8, wherein the thiophene ring and the thiazole ring in the general formulas (4a) to (4d), or the total number of rings in each thiophene ring is 5 to 40. The organic semiconductor material according to claim 8, wherein the general formula (4a) has a partial structure represented by the general formula (2). The organic semiconductor material according to claim 10, wherein Ar _{5 to} Ar ₈ in the general formula (2) are a thiophene ring and a thiazole ring, or all are thiophene rings. The organic semiconductor material according to claim 8, wherein the general formula (4b) has a partial structure represented by the general formula (3). The organic semiconductor material according to claim 12, wherein Ar _{5 to} Ar ₈ in the general formula (3) are a thiophene ring and a thiazole ring, or all are thiophene rings. The organic-semiconductor material which does not have a head-to-head structure in the structure of the organic-semiconductor material of any one of Claims 1-13. The organic-semiconductor film of any one of Claims 1-14 is contained, The organic-semiconductor film characterized by the above-mentioned. The organic-semiconductor device using the organic-semiconductor material of any one of Claims 1-14. An organic thin film transistor, wherein the organic semiconductor material according to claim 1 is used for a semiconductor layer.

Images