JP2007207966A - 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 material which can be manufactured with a simple application process, has good characteristics as a transistor, is stable for oxygen in the air, and has sufficiently suppressed secular deterioration, and to provide an organic semiconductor film employing the same, an organic semiconductor device and an organic thin-film transistor. <P>SOLUTION: The organic semiconductor material is a tetravalent platinum ortho-metallized complex having a partial structure expressed by a general formula (1). In the formula, Z<SB>1</SB>and Z<SB>2</SB>each denote a substituted or unsubstituted aromatic ring, X<SB>1</SB>and X<SB>2</SB>each denote a minus univalent anionic unidentate ligand, and they are each a ligand not existing on the same plane as a plane to be formed by Z and Z<SB>2</SB>. A<SB>1</SB>denotes a carbon or nitride atom. <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, the information that has been provided in paper media has been increasingly digitized. As a mobile display medium that is thin, light, and easy to carry, it has become electronic paper or digital paper. Needs are growing.

  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. In order to manufacture such TFT elements, a high temperature or high vacuum manufacturing process such as sputtering or plasma CVD is usually required.

  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 the above-described thin display such as electronic paper or digital paper is configured using such a conventionally known TFT element, the display is heavy and flexible. Products that may break due to chipping or dropping impact. 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 many 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, restrictions on substrate heat resistance are relaxed, and for example, a TFT element may be formed on a 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.

  Furthermore, it is considered that there is a possibility of obtaining a semiconductor that can be dissolved in a solvent by appropriately improving the molecular structure of the organic semiconductor material, and the production by the printing method including the ink jet method can be performed by converting the organic semiconductor solution into an ink. This is possible, and since the number of steps can be greatly reduced as compared with the conventional patterning method using photolithography, the cost can be further reduced.

  However, organic semiconductors for realizing such TFT elements have been studied so far such as acenes such as pentacene and tetracene (for example, see Patent Document 1), phthalocyanines including lead phthalocyanine, perylene and its tetracarboxylic acid. Low molecular weight compounds such as acid derivatives (for example, see Patent Document 2), aromatic oligomers represented by thiophene hexamers called α-thienyl or sexithiophene (for example, see Patent Document 3), naphthalene, anthracene A compound in which a member aromatic heterocycle is condensed symmetrically (for example, see Patent Document 4), mono-, oligo- and polydithienopyridine (for example, see Patent Document 5), polythiophene, polythienylene vinylene, poly-p-phenylene Limited to conjugated polymers such as vinylene However, no material has been found that exhibits sufficient carrier mobility and ON / OFF ratio while maintaining sufficient solubility in a solvent. .

  Recently, it has been reported that a single crystal of rubrene, which is a highly soluble acene, has very high mobility (see Non-Patent Document 4). Such a single crystal was produced by a vapor phase growth method. The film formed by solution casting is usually amorphous, and sufficient mobility is not obtained.

  Also disclosed is a compound in which a functional group is added to pentacene, which is a compound having high carrier mobility by vacuum deposition, and a relatively good carrier mobility can be obtained by solution coating (see, for example, Patent Document 6). ) Is also made.

  However, acene-based compounds such as rubrene and pentacene are easily oxidized by oxygen contained in the air and converted into an oxidant called end peroxide, which may greatly deteriorate the performance as a field effect transistor. It is known that there are still problems to be solved regarding the storage stability in solution and the stability of the coating film.

  With respect to the stability over time of such an organic semiconductor element, for example, JP 2003-292588 A, U.S. Patent Application Publication Nos. 2003/136958, 2003/160230, 2003/164495. In the specification, “The use of polymer TFTs in integrated circuit logic elements for microelectronics greatly improves their mechanical durability and extends their usable lifetime. However, many of the semiconductor polythiophenes are affected by ambient oxygen. Devices that are made from these materials are not stable when exposed to air because they are oxidatively doped and increase electrical conductivity, which results in high off-state currents and therefore low current on / off ratios. Therefore, many of these materials are environmental oxygenated during material processing and device manufacturing. Extreme care must be taken to eliminate or minimize oxidative doping, and this precautionary measure increases manufacturing costs, and is an economical alternative to amorphous silicon technology, especially for large area devices. As a result, there is a need for an electronic device having a strong resistance to oxygen and a relatively high current ON / OFF ratio. As described above, the problem of how to prevent the organic semiconductor material from deteriorating over time has become a major problem in practical application.

  As an example of an acene compound that is relatively stable against oxidation, in Non-Patent Documents 5 and 6, and Patent Document 7, some compounds in which the 6th and 13th positions of pentacene are substituted with silylethynyl groups are used. There are some reports that stability is good.

  However, these reports only describe qualitative properties in the text that stability against oxidation has been improved, and have not yet obtained stability enough to withstand practical use.

Thus, an organic semiconductor material having both high mobility, durability, and solubility has not been obtained yet.
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A International Publication No. 03/016599 Pamphlet US Pat. No. 6,690,029 Science 289, 599 pages (2000) “Nature” 403 volumes, 521 pages (2000) "Advanced Material", 2002, No. 2, page 99 Science, vol. 303 (2004), page 1644 Org. Lett. , Vol. 4 (2002), 15 pages J. et al. Am. Chem. Soc. , Vol. 127 (2005), 4986 pages

  An object of the present invention is to use an organic semiconductor material that can be manufactured by a simple coating process, has good characteristics as a transistor, is stable against oxygen in the air, and sufficiently suppresses deterioration over time. An organic semiconductor film, an organic semiconductor device, and an organic thin film transistor.

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

  1. An organic semiconductor material which is an orthometalated complex of tetravalent platinum having a partial structure represented by the following general formula (1).

(In the formula, Z ₁ and Z ₂ each represent a substituted or unsubstituted aromatic ring, and the substituents may be linked to each other to form a ring. X ₁ and X ₂ are a minus monovalent anionic monodentate. A ligand represents a ligand and does not exist in the same plane as the plane formed by Z and Z _2. A ₁ represents a carbon atom or a nitrogen atom.)
2. 2. The organic semiconductor material according to 1, wherein the ligand of the orthovalent metal complex of tetravalent platinum has a condensed polycyclic structure in which three or more rings are condensed.

  3. An organic semiconductor material which is a compound represented by the following general formula (2).

(In the formula, Z _{3 to} Z ₅ represent a substituted or unsubstituted aromatic ring. X ₃ represents a minus monovalent anionic monodentate ligand, and the same plane as the plane formed by Z _{3 to} Z _5. It is a ligand that does not exist in
4). A compound represented by the above general formula (1) or (2), wherein a minus monovalent anionic monodentate ligand represented by X _{1 to} X ₃ is represented by the following general formula (3): The organic semiconductor material according to any one of 1 to 3, which is a ligand.

(In the formula, A ₂ represents a functional group selected from a carbon atom, vinylene group, ethynylene group, and arylene group, and R represents a substituent selected from an alkyl group, a cycloalkyl group, an alkylsilyl group, and an (alkylsilyl) alkyl group. And n represents an integer of 1 to 3.)
5). 5. The organic semiconductor material according to 4, wherein the functional group represented by A ₂ in the general formula (3) is an ethynyl group.

  The organic-semiconductor film of any one of 6.1-5 is used, The organic-semiconductor film characterized by the above-mentioned.

  The organic-semiconductor device characterized by using the organic-semiconductor material of any one of 7.1-5.

  8.1. The organic thin-film transistor characterized by using the organic-semiconductor material of any one of 1-5 for a semiconductor layer.

  According to the present invention, an organic semiconductor material that can be manufactured by a simple coating process, has good characteristics as a transistor, is stable against oxygen in the air, and sufficiently suppresses deterioration over time. An organic semiconductor film, an organic semiconductor device, and an organic thin film transistor can be provided.

  As a result of intensive studies by the present inventors on the above problems, an ortho-metalated complex having a structure in which an aromatic compound having excellent characteristics as an organic semiconductor is combined with platinum which is a noble metal stable to oxygen is obtained. The present inventors have found that the organic semiconductor material has excellent characteristics as a semiconductor and stability to oxygen.

  Furthermore, by using a tetravalent platinum complex, it is possible to obtain a novel structure in which a soluble group is bonded in a direction perpendicular to the plane formed by the aromatic ring structure. It became a possible compound, and it discovered that a semiconductor element could be formed by a normal-pressure application | coating process, and came to complete this invention.

  In the organic semiconductor material of the present invention, an organic semiconductor material useful for thin film transistor applications can be obtained by using a compound having a structure defined in any one of claims 1 to 5. In addition, the organic semiconductor film, organic semiconductor device, and organic thin film transistor (hereinafter also referred to as organic TFT) of the present invention produced using the organic semiconductor material have high carrier mobility and good ON / OFF characteristics. It was found that the transistor had excellent transistor characteristics and high durability.

  Hereinafter, details of each component according to the present invention will be described.

[Organic semiconductor materials]
The organic semiconductor material of the present invention is a tetravalent platinum orthometalated complex having a partial structure represented by the general formula (1).

In the general formula (1), Z ₁ and Z ₂ each represents a substituted or unsubstituted aromatic ring, and the substituents may be connected to each other to form a ring. X ₁ and X ₂ represent minus monovalent anionic monodentate ligands, and are ligands that do not exist in the same plane as the plane formed by Z ₁ and Z ₂ . A ₁ represents a carbon atom or a nitrogen atom.

  Orthometalated complexes are described by Akio Yamamoto, “Organic Metal Chemistry Fundamentals and Applications,” pages 150 and 232, Hankabo (1982), H.C. Yersin's “Photochemistry and Photophysics of Coordination Compounds”, pages 71-77 and pages 135-146, Springer-Verlag (1987), etc.

In the present invention, an ortho-metalated complex is constituted by the aromatic ring structure represented by Z ₁ and Z ₂ , and further, these ligands form a π stack structure through which an electric current passes. Aromatic compounds having a large conjugated system such as oligothiophene and acene, which have been reported so far, are easily oxidized and deteriorated by oxygen. However, in the present invention, a stable metal such as platinum is difficult to be oxidized. By substituting a part of the aromatic ring, it is estimated that stability is improved and an organic semiconductor material with little deterioration is obtained. Further, since platinum is tetravalent, it becomes possible to bond a soluble substituent at an angle that does not form the same plane with respect to the aromatic plane, and an organic semiconductor material having good solubility in an organic solvent. It can be said that.

Examples of the aromatic ring represented by Z ₁ and Z ₂ in the general formula (1) include 6-membered rings such as a benzene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and a tetrazine ring. Structures and 5-membered ring structures such as pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, furan ring, benzofuran ring, isobenzofuran ring, oxazole ring, isoxazole ring, furazane ring, thiophene ring and thiazole ring Either of these can be used without limitation. However, the aromatic ring represented by Z ₂ needs to be an aromatic ring having at least one or more nitrogen atoms. These aromatic rings may have a substituent, and these substituents may be bonded to each other to form a ring.

Examples of the minus monovalent anionic monodentate ligand represented by X ₁ and X ₂ in the general formula (1) include the following anions.

  In the above structure, R represents a substituent, and m represents an integer of 0 to 3.

Since these substituents are not in the same plane as the plane formed by the aromatic rings represented by Z ₁ and Z ₂ described above, there is an effect that they can be dissolved in an organic solvent.

Examples of the substituent which may substitute the aromatic ring represented by Z ₁ and Z ₂ and the substituent R constituting a part of the minus monovalent anionic monodentate ligand include the following substitutions: The group can be mentioned.

Alkyl group: for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, neopentyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, pentadecyl group, etc.
A cycloalkyl group: for example, a cyclopentyl group, a cyclohexyl group, etc.
Alkenyl group: For example, vinyl group, allyl group, 1,2-dichloroethylene group, etc.
Alkynyl group: ethynyl group, propargyl group, diethynyl group, etc.
Aryl group (also called aromatic carbocyclic group, aromatic hydrocarbon group, etc.): for example, phenyl group, p-chlorophenyl group, tolyl group, xylyl group, mesityl group, biphenylyl group, etc.
Also naphthalene ring, anthracene ring, azulene ring, acenaphthene ring, fluorene ring, phenanthrene ring, indene ring, pyrene ring, tetracene ring, pentacene ring, hexacene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, Acenaphthylene ring, triphenylene ring, coronene ring, benzocoronene ring, hexabenzocoronene ring, benzofluorene ring, fluoranthene ring, perylene ring, naphthoperylene ring, pentabenzoperylene ring, benzoperylene ring, pentaphen ring, picene ring, pyranthrene ring, coronene ring , A substituent in which a part of hydrogen of a condensed aromatic hydrocarbon ring such as a naphtho-colonene ring, an ovarene ring or an anthraanthrene ring is replaced, etc.
Heteroaryl group (also called aromatic heterocyclic group): for example, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, acridine ring, phenanthridine ring, quinoxaline ring, Cinnoline ring, phthalazine ring, quinazoline ring, naphthyridine ring, pteridine ring, phenazine ring, phenanthroline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, indole ring, benzimidazole ring, carbazole ring, purine ring, pyrrolopyrrole ring, Pyrazolotriazole ring, benzoquinoline ring, carbazole ring, azacarbazole ring, phenazine ring, phenanthridine ring, phenanthroline ring, carboline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrin ring, trif Nodithiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (representing any one of carbon atoms constituting a carboline ring replaced by a nitrogen atom), phenanthroline ring, furan Ring, benzofuran ring, isobenzofuran ring, dibenzofuran ring, oxazole ring, isoxazole ring, oxadiazole ring, furazane ring, thiophene ring, benzothiophene ring, thieno [2,3-a] thiophene ring, thieno [2,3 -B] part of hydrogen of a condensed aromatic hydrocarbon ring such as a thiophene ring, anthradithiophene ring, dithiafulvene ring, thiazole ring, benzothiazole ring, dibenzothiophene ring, benzodithiophene ring, anthradithiophene ring, thiothiophene ring Substituent etc. that replaced
Heterocyclic group: epoxy ring, aziridine ring, thiirane ring, oxetane ring, azetidine ring, thietane ring, tetrahydrofuran ring, dioxolane ring, pyrrolidine ring, pyrazolidine ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring , Ε-caprolactone ring, ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring Tetrahydrothiopyran ring, thiomorpholine ring, thiomorpholine-1, 1-dioxide ring, pyranose ring, diazabicyclo [2,2,2] -octane ring, 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: for example, phenoxy group, naphthyloxy group, etc.
Alkylthio group: for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.
Cycloalkylthio group: for example, cyclopentylthio group, cyclohexylthio group, etc.
Arylthio group: for example, phenylthio group, naphthylthio group, etc.
Alkoxycarbonyl group: For example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.
Aryloxycarbonyl group: for example, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.
Sulfamoyl group: for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthyl An aminosulfonyl group, a 2-pyridylaminosulfonyl group, etc.
Acyl group: For example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc. Acyloxy groups (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), etc.
Amide group: For example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group Groups, phenylcarbonylamino groups, naphthylcarbonylamino groups, etc., carbamoyl groups (for example, aminocarbonyl groups, methylaminocarbonyl groups, dimethylaminocarbonyl groups, propylaminocarbonyl groups, pentylaminocarbonyl groups, cyclohexylaminocarbonyl groups, octylaminocarbonyl groups) Group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl Bonyl 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-pyridylamino group) Ureido group, etc.)
Amino group: For example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.
Halogen atom: For example, fluorine atom, chlorine atom, bromine atom, etc.
Fluorinated hydrocarbon group: For example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.
Silyl group: For example, trimethylsilyl group, triisopropylsilyl group, tricyclohexylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, trimethoxysilyl group, triethoxysilyl group, silatrane group, etc.
Siloxy group: For example, trimethylsiloxy group, triisopropylsiloxy group, tricyclohexylsiloxy group, triphenylsiloxy group, phenyldiethylsiloxy group, etc.
Sulfinyl group: For example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.
Sulfonyl group: For example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc., phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.
Other substituents: cyano group, nitro group, hydroxy group, mercapto group, alkylsilyl group, disulfide group, sulfoxide group, sulfone group, sulfoximine group, oxo group (= O), thione group (= S), phosphate ester Group, thiophosphate group, phosphorylamino group, phosphite group, etc.
Is mentioned. These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

The ligand represented by Z ₁ and Z ₂ in the general formula (1) that forms the tetravalent platinum orthometalated complex of the present invention is a ligand capable of forming a π stack structure. Although it will not specifically limit if it is, in order to obtain the organic-semiconductor thin film which has high mobility, it is preferable that it is a ligand which has the condensed polycycle which three or more rings condensed. With such a structure, there is an effect that the crystallinity of the organic thin film is improved, the π stack area between the condensed polycycles is increased in the crystal, and high mobility can be obtained.

Among these ligands, the material in which the condensed polycycle itself forms an orthometalated complex has a high molecular symmetry, so it is easy to obtain a coating film with high crystallinity, and thus high mobility coating. Easy to obtain a film. Moreover, since the atom which forms a covalent bond with platinum tends to have higher stability of the complex when it is a carbon atom, the atom represented by A ₁ is preferably a carbon atom.

  Therefore, the compound represented by the general formula (2) is more preferable.

In General formula (2), Z < ₃ > -Z < ₅ > represents a substituted or unsubstituted aromatic ring. X ₃ represents a minus monovalent anionic monodentate ligand and is a ligand that does not exist in the same plane as the plane formed by Z _{3 to} Z ₅ .

Examples of the aromatic ring represented by Z _{3 to} Z ₅ include 6-membered ring structures such as a benzene ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, and a tetrazine ring, and a pyrrole ring. , Pyrazole ring, imidazole ring, triazole ring, tetrazole ring, furan ring, benzofuran ring, isobenzofuran ring, oxazole ring, isoxazole ring, furazane ring, thiophene ring, thiazole ring, etc. Can be used without limitation. However, the aromatic ring represented by Z ₅ needs to be an aromatic ring having at least one or more nitrogen atoms.

  Examples of such condensed polycycles include benzo [h] quinoline, benzo [h] cinnoline, benzo [f] quinoxaline, benzo [c] naphthyridine, benzo [h] naphthyridine, 1,7-phenanthroline, 1,8 -Phenanthroline, 1,9-phenanthroline, 2,3,5-triazaphenanthrene, 2,5,9-triazaphenanthrene, 4,9,10-triazaphenanthrene, thieno [2,3-h] quinoline, naphtho Examples include [1,2-d] thiazole, benzo [4,5] thieno [3,2-b] pyridine, but are not limited thereto.

By the way, it is known that the characteristics of the organic semiconductor element vary greatly depending not only on the organic semiconductor material itself but also on the surface energy of the surface of the insulating film forming the organic semiconductor layer. In general, it is known that the higher the surface of the insulating film is, the higher the mobility is. Therefore, the surface of the insulating film made of SiO ₂ is made hydrophobic by a surface treatment agent such as octadecyltrichlorosilane (hereinafter also referred to as OTS). It is preferable that it is processed. On the other hand, however, if the insulating film is treated with these surface treatment agents, it becomes easy to repel a solvent having a high polarity, so that the solvent that can be applied is limited. Therefore, the minus monovalent anionic monodentate ligand X ₃ is preferably a ligand represented by the general formula (3).

  In the general formula (3), A represents a functional group selected from a carbon atom, vinylene group, ethynylene group, and arylene group, and R is selected from an alkyl group, a cycloalkyl group, an alkylsilyl group, and an (alkylsilyl) alkyl group. Represents a substituent.

  In this way, by forming a monodentate ligand having a specific substituent having a low polarity and a large contribution to improvement in solubility such as an alkyl group, a cycloalkyl group, an alkylsilyl group, and an (alkylsilyl) alkyl group, hexane, There is an effect that the solubility in a low-polar organic solvent such as cyclohexane and toluene is further improved, and it can be uniformly applied to the surface of the insulating film surface-treated with OTS or the like.

  Moreover, the stability of organic-semiconductor material can be made still higher by making the atom directly couple | bonded with a platinum atom into a carbon atom.

  In addition, it is preferable that it is 1-3 as the number n which the substituent R substitutes a minus monovalent anionic monodentate ligand. When n = 0, the solubility of the orthometalated complex may be insufficient, and when n is 4 or more, the crystallinity of the organic thin film after coating film formation may be reduced, and the characteristics as a semiconductor may be reduced. More preferably, it is 1-2, More preferably, it is 1.

  Of the minus monovalent anionic monodentate ligands represented by the general formula (3), a ligand in which the functional group A is an ethynyl group is preferable.

It is known that the conductivity of the organic semiconductor is mainly transmitted in a direction perpendicular to the plane formed by the aromatic ring, and the aromatic rings represented by Z _{1 to} Z ₅ are large in the crystal thin film. The better the semiconductor characteristics can be obtained. The minus monovalent anionic monodentate ligand X ₃ of the orthometalated complex imparts solubility to the organic semiconductor compound of the present invention, but inhibits the overlap of the aromatic rings represented by Z _{1 to} Z _5. . When the functional group A ₂ is an ethynyl group which is a linear functional group, the overlap between the aromatic rings Z _{1 to} Z ₅ can be maximized. For this reason, it is possible to obtain an organic semiconductor thin film having high mobility and further high mobility while solubilizing the orthometalated complex.

  The molecular weight of these orthometalated complexes is preferably in the range of 300-5000. By setting the molecular weight to 300 or more, the volatility of the compound can be sufficiently lowered, and volatilization during production and process contamination can be prevented. Moreover, the solubility to a solvent can be kept in a favorable range by setting it as 5000 or less. In addition, when forming a semiconductor layer by vapor deposition, it is preferable that molecular weight is 1000 or less. By setting it as such a range, film-forming can be performed with a comparatively low degree of vacuum, and productivity can be made high. The molecular weight of the organic semiconductor material of the present invention can be measured with a mass spectrometer, GPC, or the like.

  Hereinafter, although the specific example of the organic-semiconductor material of this invention is shown, this invention is not limited to these.

  In addition, said compound is Inorg. Chem. , Vol. 41 (2002), p3055.

[Organic semiconductor film, organic semiconductor device, organic thin film transistor]
The organic semiconductor film, organic semiconductor device, and organic thin film transistor of the present invention will be described.

  When the organic semiconductor material of the present invention is used for a semiconductor layer of an organic semiconductor film, an organic semiconductor device, or an organic thin film transistor, an organic semiconductor device and an organic thin film transistor that are driven well can be provided. An organic thin film transistor has a top gate type having a source electrode and a drain electrode connected with an organic semiconductor as a semiconductor layer on a support, and having a gate electrode on the support via a gate insulating layer. It is roughly classified into a bottom gate type having a gate electrode and having a source electrode and a drain electrode connected by an organic semiconductor through a gate insulating layer.

  In order to install the organic semiconductor material of the present invention in an organic semiconductor film, an organic semiconductor device, or a semiconductor layer of an organic thin film transistor, a vacuum vapor deposition method or a solution coating method can be appropriately selected according to the characteristics of the material. However, since it is easier to form a film by the solution coating method and the area can be easily increased, it is preferable to form the organic semiconductor layer by the solution coating method if the material has high solubility. Examples of the solution coating method include cast coating, spin coating, printing, ink jet method, and ablation method. The coating method may be selected according to coating speed, definition, substrate material to be formed, viscosity of the solution to be used, and 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, N-methylpyrrolidone, carbon disulfide and the like. Of these solvents, a solvent containing a non-halogen solvent is preferable, and a non-halogen solvent is preferable. In addition, when the insulating film surface is applied on an insulating film hydrophobized, it is preferably a nonpolar solvent having a surface energy smaller than the surface energy of such a hydrophobic surface, such as hexane, cyclohexane, toluene. Etc. are preferred.

  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. The semiconductor layer is preferably formed by applying a solution or dispersion containing these organic semiconductor materials.

  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 a relief printing plate, an intaglio printing plate, a planographic printing plate or a screen printing can 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, JP-A-2000-185362 (hereinafter referred to as atmospheric pressure). Also called plasma method). 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), Examples include films made of triacetyl cellulose (TAC), diacetyl cellulose (DAC), cellulose acetate propionate (CAP), and 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 the two electrodes, and a substrate is formed thereon. An insulating layer 5 is formed, and a 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, and the source electrode 2 and the drain electrode 3 are formed on the metal foil or the like on the insulating layer 5. An organic semiconductor layer 1 made 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 this 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.

The performance of the organic thin film transistor, but is the performance changes needed depending on the application, for example, in applications such as electronic paper, the carrier mobility 0.01 (1.0 × 10 ^-2) ~1 It is preferably in the range of 0.0 cm ² / Vsec, and the ON / OFF ratio is preferably in the range of 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ . By setting it as such a range, a display can be driven at sufficient speed and a favorable gradation can be provided to a display.

  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 0.01 Ω · cm as a gate electrode to form a gate insulating layer, and then surface treatment with octadecyltrichlorosilane was performed.

  On a Si wafer subjected to such a surface treatment, Comparative Compound 1 (Pentacene, manufactured by Aldrich, used after sublimation purification of a commercially available reagent) was added to toluene that was bubbled with nitrogen for 30 minutes in a nitrogen atmosphere. , Dissolved at a concentration of 5% by mass, spin-coated under a nitrogen atmosphere (rotation speed: 2500 rpm, 15 seconds), naturally dried to form a cast film, and heat-treated at 50 ° C. for 30 minutes in a nitrogen atmosphere Was given.

  Further, gold was deposited on the surface of this film using a mask to form a source electrode and a drain electrode. An organic thin film transistor 1 having a source electrode and a drain electrode having a width of 100 μm, a thickness of 200 nm, a channel width W = 3 mm, and a channel length L = 20 μm was produced.

<< Production of Organic Thin Film Transistor 2 >>
Comparative compound 2 (2,3,9,10-tetrahexylpentacene) is described in Organic Letters, vol. 2 (2000), p85.

  An organic thin film transistor 2 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 2.

<< Production of Organic Thin Film Transistor 3 >>
In the production of the organic thin film transistor 1, the organic thin film transistor 3 was produced in the same manner except that the comparative compound 1 was changed to the comparative compound 3 (Lubrene, manufactured by Aldrich, used after sublimation purification of a commercially available reagent).

<< Production of Organic Thin Film Transistor 4 >>
An organic thin film transistor 4 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 4.

  Comparative compound 4 is described in J. Org. Am. Chem. Soc. , Vol. 123 (2001), p9482, supporting information.

<< Production of Organic Thin Film Transistor 5 >>
An organic thin film transistor 5 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 5.

  Comparative compound 5 was synthesized by the method described in Non-Patent Document 6.

<< Production of Organic Thin Film Transistor 6-10 >>
In the production of the organic thin film transistor 1, organic thin film transistors 6 to 10 were produced in the same manner except that the organic semiconductor material of the present invention described in Table 1 was used instead of the comparative compound 1.

<< Evaluation of carrier mobility and ON / OFF ratio >>
About the obtained organic thin-film transistors 1-10, the carrier mobility and ON / OFF ratio of each element were measured immediately after element preparation. 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 values when the drain bias is −50 V and the gate bias is −50 V and 0 V. It was.

  In addition, the same evaluation was performed by putting each element into an environmental chamber at 40 ° C. and 90% RH for 48 hours, and then re-measuring the carrier mobility and ON / OFF ratio.

  The obtained results are shown in Table 1.

  From Table 1, the comparative compound 1 has low solubility, and a film cannot be formed by coating, and the organic thin film transistor 1 could not be confirmed as a transistor.

Comparative compounds 2 and 3 were more soluble than comparative compound 1 and formed a coating film. Organic thin film transistors 2 and 3 were confirmed to be driven as transistors. It can be seen that the OFF ratio is relatively low at 10 ³ units or less, and that the performance is greatly deteriorated after the durability test.

The organic thin film transistors 4 and 5 showed sufficient transistor performance immediately after coating and film formation, but the mobility was 10 ⁻³ units and the ON / OFF ratio was 10 ⁴ units after the endurance test. Not held up to.

On the other hand, the organic thin film transistors 6 to 10 manufactured using the organic semiconductor material of the present invention show excellent characteristics in both carrier mobility and ON / OFF ratio immediately after the manufacture, and the mobility is 10 ⁻ after the durability test. It can be seen that there are ^two or more units, and the ON / OFF ratio is 10 ⁵ units or more, and there is little deterioration with time and high durability.

Among the organic thin film transistors of the present invention, organic thin film transistors 8 to 10 using a compound having a tricyclic condensation type ligand obtain an element having a high mobility of about 10 ⁻¹ immediately after film formation. I can see that Among them, the organic thin film transistor 9 having an ethynyl group as a monodentate ligand has a very excellent mobility of 10 ⁻¹ even after an endurance test, and has both transistor characteristics and stability. It can be seen that a thin film transistor is obtained.

Example 2
<< Production of organic EL element >>
The organic EL element was produced by referring to the method described in Nature, Vol. 395, pages 151 to 154, and producing 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 organic EL 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 of the present invention may be either a bottom emission type or a top emission type.

  The organic EL element of 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 produced to produce an active matrix light emitting element. For example, as shown in FIG. 4, a mode in which a substrate in which a TFT 602 (or an organic thin film transistor 602 may be formed) is formed on a glass substrate 601 is used as an example. 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 TFT or bottom gate 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 TFT which concerns on this invention. It is an example of the schematic equivalent circuit schematic of the organic TFT 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 101 Substrate 102 Organic EL element 102a Anode 102b Organic EL layer 102c Cathode 103 Sealing film 601 Glass substrate 602 TFT

Claims (8)

An organic semiconductor material which is an orthometalated complex of tetravalent platinum having a partial structure represented by the following general formula (1).

(In the formula, Z ₁ and Z ₂ each represent a substituted or unsubstituted aromatic ring, and the substituents may be linked to each other to form a ring. X ₁ and X ₂ are a minus monovalent anionic monodentate. A ligand represents a ligand and does not exist in the same plane as the plane formed by Z and Z _2. A ₁ represents a carbon atom or a nitrogen atom.) The organic semiconductor material according to claim 1, wherein the ligand of the tetravalent platinum orthometalated complex has a condensed polycyclic structure in which three or more rings are condensed. An organic semiconductor material which is a compound represented by the following general formula (2).

(In the formula, Z _{3 to} Z ₅ represent a substituted or unsubstituted aromatic ring. X ₃ represents a minus monovalent anionic monodentate ligand, and the same plane as the plane formed by Z _{3 to} Z _5. It is a ligand that does not exist in A compound represented by the above general formula (1) or (2), wherein a minus monovalent anionic monodentate ligand represented by X _{1 to} X ₃ is represented by the following general formula (3): It is a ligand, The organic-semiconductor material of any one of Claims 1-3 characterized by the above-mentioned.

(In the formula, A ₂ represents a functional group selected from a carbon atom, vinylene group, ethynylene group, and arylene group, and R represents a substituent selected from an alkyl group, a cycloalkyl group, an alkylsilyl group, and an (alkylsilyl) alkyl group. And n represents an integer of 1 to 3.) The organic semiconductor material according to claim 4, wherein the functional group represented by A ₂ in the general formula (3) is an ethynyl group. The organic-semiconductor film of any one of Claims 1-5 is used, The organic-semiconductor film characterized by the above-mentioned. The organic-semiconductor device characterized by using the organic-semiconductor material of any one of Claims 1-5. An organic thin film transistor using the organic semiconductor material according to claim 1 for a semiconductor layer.

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