JP6833445B2 - Organic transistor - Google Patents

Description

The present invention relates to an organic transistor. More specifically, the present invention relates to an organic transistor in which a specific organic compound is used in an organic semiconductor layer.

Conventionally, a thin film transistor (TFT) made of amorphous silicon or polycrystalline silicon has been widely used as a switching element for flat panel display such as a liquid crystal display device. However, the CVD apparatus used for producing the thin film transistor using these silicons is expensive, and the production of a large thin film transistor element has a drawback that the production cost is increased.
Further, since the film formation of amorphous silicon or polycrystalline silicon is carried out at a high temperature, there is a drawback that a plastic material having poor heat resistance cannot be used as a substrate, although it is lightweight and flexible. ..
In order to solve the above problem, an organic transistor (also referred to as an organic thin film transistor or an organic TFT) using an organic compound for a channel semiconductor layer (hereinafter referred to as an organic semiconductor layer) instead of amorphous silicon or polycrystalline silicon has been proposed. (Non-Patent Document 1).

As a method for forming the organic semiconductor layer, for example, a vacuum vapor deposition method and a coating method are known. According to these film forming methods, it becomes easy to increase the size of the organic transistor element while suppressing the manufacturing cost. ..
Furthermore, the temperature required for film formation can be lowered, and in organic transistors using organic compounds, it is possible to use a plastic material for the substrate, which makes it possible to apply it to flexible display elements, and its practical use. Expectations are gathering for the conversion.

Practical organic transistors need to have characteristics such as high charge mobility and a large current on / off ratio. Here, the term "on / off ratio" means the ratio of the current between the source electrode and the drain electrode when the organic transistor is on to the current between the source electrode and the drain electrode when the organic transistor is off. To do.
Furthermore, excellent storage stability is required for the practical use of organic transistors.

To date, organic transistors using, for example, pentacene have been proposed for the organic semiconductor layer (Non-Patent Document 2).
However, an organic transistor using pentacene has a drawback that its function as an organic transistor is low in the atmosphere and its storage stability is low.
Further, an organic transistor using a thiophene oligomer (α-hexathienylene) in an organic semiconductor layer has been proposed (Non-Patent Document 3). However, the organic transistor also has a drawback of low storage stability in air.

As an improvement to these drawbacks, for example, an organic transistor using a compound of the formula (A) or the formula (B) in the organic semiconductor layer has been proposed (Patent Document 1).

Further, for example, a method for producing a compound of the formulas (C) to (F) is disclosed, and the compound produced by the method is known to be useful as a material for an organic transistor (Patent Document 2). ..

Further, for example, an organic transistor using an alkoxyalkyl group or a compound having an alkoxyalkoxy group as a substituent, such as the compounds of the formulas (G) and (H), in the organic semiconductor layer is known (Patented). Document 3).

Further, for example, methods for producing the compounds of the formulas (I) and (J) are disclosed, and the compounds produced by the methods are reported to be useful as organic semiconductor materials (Patent Document 4).

Further, for example, an organic transistor in which a compound having a branched-chain alkyl group such as the compound of the formula (K) is used for the organic semiconductor layer has been proposed (Patent Document 5).

It was found that the charge mobility of the organic transistor using the compounds of the formulas (B), (D) and (J) in the organic semiconductor layer is relatively high, but the storage stability (moisture and heat resistance) is difficult. ..
Further, it was found that the charge mobility of the organic transistor using the compounds of the formulas (A), (C), formulas (E) to (I) and formula (K) in the organic semiconductor layer was low.
Furthermore, it was found that the compounds of formulas (E) to (H) and formulas (K) also have difficulty in storage stability (moisture and heat resistance).

At present, there is a demand for the development of further improved organic transistors for practical use.

JP-A-2010-34450 Japanese Unexamined Patent Publication No. 2011-256144 Japanese Unexamined Patent Publication No. 2011-258900 WO2014 / 030700 Japanese Patent Publication No. 2014-531435

Apple. Phys. Lett. , 63, 1372 (1993) Apple. Phys. Lett. , 72, 1854 (1998) Science, 268,270 (1995)

To date, organic transistors using various organic compounds for the organic semiconductor layer have been proposed, but it is difficult to say that all of them have sufficiently satisfactory characteristics for practical use. ..
In view of the above, the present invention provides an organic transistor having high charge mobility, a large current on / off ratio, and excellent storage stability (moisture and heat resistance).

As a result of diligent studies to solve the above problems, the present inventor has found that an organic transistor containing at least one compound selected from the compounds represented by the general formula (1) in an organic semiconductor layer has charge mobility. We have found that the mobility is high, the current on / off ratio is large, and the storage stability (moisture and heat resistance) is excellent, and the present invention has been completed.

（式中、Ｘ_１およびＸ_２は、一方が炭素数２〜１２の直鎖状のアルキル基を表し、他方が水素原子を表す）
That is, the present invention is an organic transistor having an organic semiconductor layer, wherein the organic semiconductor layer contains at least one compound selected from the compounds represented by the general formula (1).

(In the formula, X ₁ and X ₂ represent a linear alkyl group having 2 to 12 carbon atoms, and the other represents a hydrogen atom.)

INDUSTRIAL APPLICABILITY According to the present invention, it has become possible to provide an organic transistor having high charge mobility, a large current on / off ratio, and excellent storage stability (moisture and heat resistance).

It is a schematic cross-sectional view of the organic transistor of this invention. It is a schematic cross-sectional view of the organic transistor of this invention. It is a schematic cross-sectional view of the organic transistor of this invention. It is a schematic cross-sectional view of the organic transistor of this invention.

（式中、Ｘ_１およびＸ_２は、一方が炭素数２〜１２の直鎖状のアルキル基を表し、他方が水素原子を表す） Hereinafter, the present invention will be described in detail.
The organic transistor of the present invention comprises an organic semiconductor layer containing at least one compound selected from the compounds represented by the general formula (1).

(In the formula, X ₁ and X ₂ represent a linear alkyl group having 2 to 12 carbon atoms, and the other represents a hydrogen atom.)

_{One of X 1} and X ₂ in the compound represented by the general formula (1) represents a linear alkyl group having 2 to 12 carbon atoms, and the other represents a hydrogen atom.
Specific examples of the linear alkyl group having 2 to 12 carbon atoms in the general formula the substituents X ₁ in the compound represented by (1) and X _2, for example, ethyl group, n- propyl group, n- butyl Examples thereof include a group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group and an n-dodecyl group.

In the compound represented by the general formula (1), more preferably, X ₁ is a linear alkyl group having 3 to 10 carbon atoms, and X ₂ is a hydrogen atom, and even more preferably, X 1 is carbon. It is a linear alkyl group of the number 4 to 10, and X ₂ is a hydrogen atom.
Further, in the compound represented by the general formula (1), X ₁ is more preferably a hydrogen atom and X ₂ is a linear alkyl group having 3 to 10 carbon atoms, and more preferably X ₁ Is a hydrogen atom, and X ₂ is a linear alkyl group having 4 to 10 carbon atoms.

Specific examples of the compound represented by the general formula (1) according to the present invention include the following compounds.

The compound represented by the general formula (1) according to the present invention can be produced with reference to a method known per se.
That is, the compound represented by the general formula (1) is, for example, an acid (for example, alkyl sulphonic acid such as methanesulphonic acid or trifluoromethanesulphonic acid) in addition to the compound represented by the general formula (2) or the general formula (3). Acids) can optionally be produced by allowing the product to act in the presence of a dehydrating agent (eg, phosphorus pentoxide) followed by a base (eg, pyridine, quinoline) on the product [eg, Macromolecules]. , 26,7144 (1993), J.Mater.Chem., 9, 2095 (1999)].

〔式中、Ｘ１ およびＸ２は一般式（１）の場合と同じ意味を表す〕

[In the formula, X1 and X2 have the same meaning as in the general formula (1)]

The compound represented by the general formula (1) according to the present invention may be produced in a mold in which a solvation is formed with a solvent used in some cases (for example, an aromatic hydrocarbon solvent such as toluene). However, in the organic transistor of the present invention, not only a solvent-free product of the compound represented by the general formula (1) but also such a solvate can be used.
When the compound represented by the general formula (1) is used for an organic transistor, a purification method such as a recrystallization method, a column chromatography method, or a sublimation purification method, or a compound whose purity is increased by using these methods in combination. It is preferable to use.

The organic transistor of the present invention is characterized in that the organic semiconductor layer contains at least one compound represented by the general formula (1), which results in high charge mobility and current, which has never been seen before. It is possible to provide an organic transistor having a large on / off ratio and excellent storage stability.
The compound represented by the general formula (1) in the organic semiconductor layer may be in the form of amorphous or crystalline, and more preferably in the form of crystals. The crystal may be in a single crystal state or a polycrystalline state.

The organic transistor usually includes a source electrode, a drain electrode and a gate electrode, a gate insulating layer, and an organic semiconductor layer. In the organic transistor of the present invention, the organic semiconductor layer has the general formula (1). It contains at least one compound represented by.

The form of the organic transistor of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing one form of the organic transistor of the present invention. In the form of this organic transistor, a gate electrode 21 is provided on a substrate 11, a gate insulating layer 31 is laminated on the gate electrode, and a source electrode 61 and a drain electrode are formed on the gate electrode 61 at predetermined intervals. 41 is formed, and an organic semiconductor layer 51 is laminated on the organic semiconductor layer 51 (bottom gate / bottom contact structure).

In the form of the organic transistor shown in FIG. 2, the gate electrode 22 is provided on the substrate 12, the gate insulating layer 32 is laminated on the gate electrode, and the organic semiconductor layer 52 is laminated on the gate insulating layer 32. Further, a source electrode 62 and a drain electrode 42 are formed on the source electrode 62 and a drain electrode 42 at predetermined intervals (bottom gate / top contact structure).

Further, in the form of the organic transistor shown in FIG. 3, a source electrode 63 and a drain electrode 43 are formed on the substrate 13 at predetermined intervals, and an organic semiconductor layer 53 is laminated on the source electrode 63 and the drain electrode 43. A gate insulating layer 33 is laminated on the gate insulating layer 33, and a gate electrode 23 is provided on the gate insulating layer 33 (top gate / bottom contact structure).

In the form of the organic transistor shown in FIG. 4, an organic semiconductor layer 54 is laminated on a substrate 14, and a source electrode 64 and a drain electrode 44 are formed on the organic semiconductor layer 54 at predetermined intervals. A gate insulating layer 34 is laminated on the top, and a gate electrode 24 is further provided on the gate insulating layer 34 (top gate / top contact structure).

In an organic transistor having such a configuration, the organic semiconductor layer forms a channel region, and the voltage applied to the gate electrode controls the current flowing between the source electrode and the drain electrode to turn it on / off. Operate.
Further, the organic transistor of the present invention can also take the form of a vertical organic transistor or a stepped organic transistor [for example, described in Applied Physics, Vol. 79, 993 (2010)].

The substrate used for the organic transistor of the present invention is not particularly limited, but in general, glass, quartz, silicon single crystal, polycrystalline silicon, amorphous silicon, paper, ceramic, plastic substrate and the like can be used. .. Furthermore, a composite substrate in which these are combined can also be used, and may be in the form of a single-layer structure or a multi-layer structure.

Examples of the plastic substrate include polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, boron carbonate, triacetyl cellulose, cellulose acetate propionate and the like. The substrate can be mentioned.
When a conductive substrate, for example, silicon is used as the substrate, the substrate can also serve as a gate electrode.
In the organic transistor of the present invention, the material used for the source electrode, the drain electrode, and the gate electrode is not particularly limited, and any conductive material can be used.

Examples of the electrode material include indium tin oxide alloy (ITO), tin oxide (NESA), indium zinc oxide (IZO), molybdenum oxide, gold, silver, platinum, copper, indium, aluminum, magnesium, nickel, chromium, and iron. , Tin, tantalum, palladium, tellurium, iridium, ruthenium, germanium, tungsten, molybdenum, lithium, beryllium, sodium, potassium, calcium, zinc, magnesium / indium alloy, magnesium / copper alloy, magnesium / silver alloy, magnesium / aluminum alloy Metals and alloys such as chromium / molybdenum alloys, aluminum / lithium alloys, aluminum / scandium / lithium alloys, sodium / potassium alloys, fluorine-doped zinc oxide, silicon single crystals with improved conductivity, polycrystalline silicon, Silicon-based materials such as amorphous silicon, carbon materials such as carbon black, graphite, and glassy carbon can be mentioned, and more preferably, indium tin oxide alloy, gold, silver, platinum, copper, indium, aluminum, and conductivity. It is an improved silicon-based material and carbon material. These can be used in various forms such as bulk, flaky, and fine particles.

Further, as the electrode material, a conductive polymer whose conductivity has been improved by doping treatment or the like (for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, a complex of polyethylene dioxythiophene (PEDOT) and polystyrene sulfonic acid, etc.) Is also preferably used.
It should be noted that one of these electrode materials may be used alone, or a plurality of these electrode materials may be used in combination.
Among the electrode materials listed above, the source electrode and the drain electrode preferably have a small electrical resistance on the contact surface with the organic semiconductor layer.

The method for forming each electrode is not particularly limited, but for example, a conductive material can be formed by using a method such as thin film deposition or sputtering, and patterning into a desired shape by lithograph or etching treatment. it can.
Further, when the electrode is formed by using the conductive polymer or the conductive fine particles, the solution or dispersion of the conductive polymer or the dispersion of the conductive fine particles may be patterned by an inkjet method, and may be patterned from the coating film. It may be formed by lithograph, laser ablation, or the like. Furthermore, inks containing conductive polymers and fine particles, conductive pastes (silver paste, gold paste, carbon paste, etc.) are patterned by letterpress, intaglio, lithographic printing, screen printing, gravure printing, and other printing methods, and inkjet methods. You can also use the method of

The film thickness of the source electrode and the drain electrode is not particularly limited, but is generally preferably set in the range of several nm to several hundred μm, more preferably 1 nm to 100 μm, and further preferably 10 nm. It is ~ 20 μm.
The source electrode and the drain electrode are arranged so as to face each other, but the interval (channel length) is generally preferably set in the range of several hundred nm to several mm, and more preferably 100 nm to 100 nm. It is 1 mm, more preferably 1 μm to 500 μm.

Further, the surfaces of the source electrode and the drain electrode are surfaced with an aliphatic alkyl thiol compound such as 4,4-dimethylpentanethiol, perfluorohexanethiol, perfluoroheptanethiol and perfluorooctanethiol, for example, 4-fluorothiophenol. 2,4,6-trifluorothiophenol, 2,3,5,6-tetrafluorothiophenol, pentafluorothiophenol, 4-trifluoromethylthiophenol, 3,5-bistrifluoromethylthiophenol, 4-nitrothio It may be modified with an aromatic thiol compound such as phenol.

As the material used for the gate insulating layer, various insulating materials can be used, and an inorganic insulator or an organic polymer compound is preferable.
Examples of the inorganic insulator include silicon oxide (SiO ₂ ), silicon nitride, aluminum oxide, aluminum nitride, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium titanate, barium titanate, and lead titanate. , Lead lanthanum titanate, strontium titanate, barium titanate, magnesium fluoride barium, bismuth titanate, strontium titanate bismuth, strontium titanate bismuth, bismuth niobate tantalate, trioxide ittrium, etc. Preferred are silicon oxide, silicon nitride, aluminum oxide, tantalum oxide and titanium oxide.

Examples of the method for forming the gate insulating layer made of an inorganic insulator include a vacuum deposition method, 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, and an atmospheric pressure plasma. Dry process such as method, spray coating method, spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating method, air knife method, slide hopper method, extrusion. Examples include a coating method such as a method, and a wet process such as various printing methods and an inkjet method, which can be appropriately selected and applied according to the characteristics of the material to be used. Further, when a silicon-based material is used as the gate electrode and the gate insulating layer is formed before the formation of the organic semiconductor, it may be formed by a thermal oxidation method.

Examples of the organic polymer compound used for the gate insulating layer include polyimide, polyamide, polyester, polyacrylate, a photoradical polymerization-based photocurable resin, a photocationic polymerization-based photocurable resin, or a copolymer containing an acrylonitrile component. , Polyvinylphenol, polyvinyl alcohol, polystyrene, novolak resin, polyvinylidene fluoride, cyanoethylplurane, poly (perfluoroalkenyl vinyl ether), parylene and the like can be used. A wet process is preferable as a method for forming the gate insulating layer using an organic polymer compound.
As the insulating material used for the gate insulating layer, one type may be used alone, or a plurality of types may be used in combination.

When silicon oxide is used as the inorganic insulator in the gate insulating layer, for example, the surface of silicon oxide that becomes an interface with the organic semiconductor layer is hexamethyldisilazane, octadecyltrimethoxysilane, octyltrichlorosilane, or the like. Octadecyltrichlorosilane, benzyltrichlorosilane, 1-hexylphosphonic acid, 1-octylphosphonic acid, 1-hexadecylphosphonic acid, 3,7,11,15-tetramethyl-1-hexadecylphosphonic acid, etc. It may have been processed.
When the organic polymer compound is used for the gate insulating layer and the organic semiconductor layer is formed after the gate insulating layer is formed, the organic semiconductor layer is subjected to a rubbing treatment on the gate insulating layer made of the organic polymer compound. May be formed.
The film thickness of the gate insulating layer is not particularly limited, but is generally preferably set in the range of several nm to several tens of μm, more preferably 5 nm to 10 μm, and further preferably 10 nm to 5 μm. Is.

The organic transistor of the present invention comprises at least one compound represented by the general formula (1) in the organic semiconductor layer, and the compound represented by the general formula (1) contains only one compound alone. It may be used, or a plurality of types may be used in combination.

Further, the organic semiconductor layer includes at least one compound represented by the general formula (1) and other carrier transporting compounds (for example, polyacetylene derivative, polythiophene derivative, polythienylene vinylene derivative, polyphenylene derivative, polyphenylene vinylene derivative). , Polypyrrole derivative, polyaniline derivative, polyarylamine derivative, polyquinoline derivative, perylene derivative, tetracene derivative, pentacene derivative, phthalocyanine derivative, etc.) may be used in combination. In this case, the content of the compound represented by the general formula (1) is preferably 20% by mass or more, and more preferably 50% by mass or more.

Further, the organic semiconductor layer may be formed of at least one compound represented by the general formula (1) and a polymer compound.
Examples of the polymer compound include polyacrylic acid derivatives, polymethacrylic acid derivatives, poly (cyclohexylmethacrylate) derivatives, polyethylene derivatives, polypropylene derivatives, polyisobutylene derivatives, polybutadiene derivatives, polyisobutylene derivatives, polymethylpentene derivatives, and poly (polyisobutylene derivatives). Vinylcyclohexane) derivative, polystyrene derivative, poly (4-methylstyrene) derivative, poly (α-methylstyrene) derivative, poly (α-vinylnaphthalene) derivative, poly (vinyltoluene) derivative, poly (chlorotrifluoroethylene) derivative , Poly (4-vinylbiphenyl) derivative, Poly (2-methyl-1,3-butadiene) derivative, Poly (styrene / acrylonitrile) copolymer, Poly (styrene / butadiene) copolymer, Polyvinyl chloride derivative, Polyethylene Examples thereof include terephthalate derivatives, polybutylene terephthalate derivatives, nylon derivatives, polyester derivatives, polyimide derivatives, polyphenol derivatives, cellulose derivatives, vinylon derivatives and the like.
One of these polymer compounds may be used alone, or a plurality of these polymer compounds may be used in combination.
When an organic semiconductor layer is formed by using a polymer compound in combination with at least one compound represented by the general formula (1), the content of at least one compound represented by the general formula (1) is contained. The amount is preferably 5% by mass or more, and more preferably 20% by mass or more with respect to the polymer compound.

The organic transistor of the present invention functions as a p-type (hole functions as a carrier) organic transistor or an n-type (electrons function as a carrier) organic transistor, but is preferably as a p-type organic transistor. It is preferable to use it.

The method for forming the organic semiconductor layer is not particularly limited, and a known forming method can be used.
Examples of the forming method include a vacuum vapor deposition method, 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, a plasma polymerization method, a thermal transfer method, and a laser transfer method. Dry process, spray coating method, spin coating method, blade coating method, dip coating method, casting method, roll coating method, bar coating method, die coating method, LB method (Langmuir Brodget method), various printing methods, inkjet method Wet processes such as.

When the organic semiconductor layer is formed by a wet process, a solution in which at least one compound represented by the general formula (1) is dissolved or dispersed in a solvent is used.
Examples of the solvent include water, methanol, ethanol, isopropyl alcohol, butanol, hexanol, methyl cellosolve, ethyl cellosolve, ethylene glycol, 1,2-propanediol, 1,3-propanediol, octafluoropentanol, and pentafluoro. Alcohol solvents such as propanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, acetophenone, propiophenone, ester solvents such as ethyl acetate, butyl acetate, γ-butyrolactone, diethyl ether, Ether solvents such as dibutyl ether, dioxane, tetrahydrofuran, cyclopentylmethyl ether, anisole, dimethoxybenzene, dimethylanisole, 4-tert-butylanisole, 2-methoxynaphthalene, hexane, heptane, octane, decane, toluene, xylene, ethylbenzene, Hydrocarbon solvents such as cumene, mesitylene, 1,2,3,4-tetrahydronaphthalene, indan, phenylcyclohexane, decahydronaphthalene, trimethylcyclohexane, bicyclohexyl, dichloromethane, chloroform, dichloroethane, tetrachloroethane, tetrachloroethylene, chlorobenzene, fluoro Halogened hydrocarbon solvents such as benzene, dichlorobenzene, trichlorobenzene, 1-fluoronaphthalene, 1-chloronaphthalene, nitrile solvents such as acetonitrile, propionitrile, methoxynitrile, glutalogie nitrile, benzonitrile, dimethyl sulfo Aprotonic polar solvents such as xside, sulforan, N, N-dimethylformamide, N, N-dimethylacetamide, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, tetramethylurea, etc. Organic solvent can be mentioned. One of these solvents may be used alone, or a plurality of these solvents may be used in combination.
The concentration of at least one compound represented by the general formula (1) in the solvent is not particularly limited, but is generally 0.01 to 20% by mass, more preferably 0.05 to 0.05. It is preferably prepared to about 15% by mass.

The film thickness of the organic semiconductor layer is not particularly limited, but is generally preferably set in the range of several nm to several tens of μm, more preferably 1 nm to 10 μm, and further preferably 5 nm to 5 nm. It is 1 μm.
In the present invention, after the formation of the organic semiconductor layer, post-treatment may be further performed if desired.
For example, after the formation of the organic semiconductor layer, heat treatment may be performed to alleviate the distortion of the film thickness generated during the formation, or to improve the generated pinholes and the like.
In addition, it may be preferable to perform heat treatment for the purpose of controlling the arrangement and orientation of molecules in the organic semiconductor layer.
The temperature of the heat treatment is not particularly limited, but the heat treatment is carried out at room temperature to about 200 ° C., preferably 40 ° C. to 150 ° C. The heat treatment may be carried out in air or in an atmosphere of an inert gas such as nitrogen or argon.

In the organic transistor of the present invention, the organic semiconductor layer may be subjected to a doping treatment, if desired. As the dopant, either a donor-type dopant or an acceptor-type dopant can be used, and it is preferable to use an acceptor-type dopant.

As the donor dopant, any compound having a function of donating electrons to the organic compound of the organic semiconductor layer can be preferably used.
Examples of the donor dopant include alkali metals such as Li, Na, K, Rb and Cs, alkaline earth metals such as Ca, Sr and Ba, Y, La, Ce, Pr, Nd and Sm.
Rare earth metals such as Eu, Gd, Tb, Dy, Ho, Er, Yb, ammonium ions, R4P + (R represents an alkyl group), R4As + (R represents an alkyl group), R3S + (R represents an alkyl group) , Acetylcholine and the like.

As the acceptor-type dopant, any compound having a function of removing electrons from the organic compound of the organic semiconductor layer can be preferably used.
Acceptable dopants include, for example, Cl ₂ , Br ₂ , I ₂ , ICl, ICl ₃ ,
Halogen compounds such as IBr and IF, PF ₅ , AsF ₅ , SbF ₅ , BF ₃ , BCl ₃ ,
Lewis acids such as BBr ₃ , SO ₃ , HF, HCl, HNO ₃ , H ₂ SO ₄ , HClO ₄ ,
Protonic acids such as FSO ₃ H, ClSO ₃ H, CF ₃ SO ₃ H, organic acids such as acetic acid, formic acid and amino acids, FeCl ₃ , FeOCl, TiCl ₄ , ZrCl ₄ , _{HfCl 4} , NbF ₅ ,
NbCl ₅ , TaCl ₅ , MoCl ₅ , WF ₅ , WCl ₆ , UF ₆ , LnCl ₃ (Ln =)
Lanthanoids such as La, Ce, Nd, Pr and transition metal compounds such as Y), Cl-, Br-,
_{I-, ClO 4 -, PF 6} -, AsF 5 -, SbF 6 -, BF 4 -, etc. electrolyte anions such as sulfonate anions.
As the doping method, a method of introducing a dopant after forming the organic semiconductor layer, or a method of introducing a dopant at the time of forming the organic semiconductor layer can be applied.

Further, in the organic transistor of the present invention, a gas barrier layer may be provided on the entire surface or a part of the outer peripheral surface of the organic transistor for the purpose of reducing the influence of oxygen, moisture and the like in the atmosphere. Examples of the material for forming the gas barrier layer include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, and poly (perfluoroalkenyl vinyl ether). Further, the inorganic insulator mentioned as the material used for the gate insulating layer can also be used for forming the gas barrier layer.
The organic transistor of the present invention can be used, for example, in a liquid crystal display element, an organic electroluminescent element, electronic paper, various sensors, RFIDs (radio frequency identification cards), and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
(Example 1)
_{A thermal oxide film (SiO 2} ) having a thickness of 200 nm was formed on a silicon substrate having a resistivity of 0.02 Ω · cm as a gate electrode. Here, the silicon substrate itself serves as a gate electrode, and the SiO ₂ layer formed on the surface of the silicon substrate serves as a gate insulating layer. On this, under vacuum (5 × 10-4 Pa), the compound of Exemplified Compound No. 1 was vapor-deposited at a vapor deposition rate of 0.03 nm / sec to a thickness of 30 nm to form an organic semiconductor layer. Further, on this, gold was vapor-deposited using a mask to form a source electrode and a drain electrode. The thickness of the source electrode and the drain electrode was 40 nm, the channel width was 5 mm, and the channel length was 70 μm.
The organic transistor produced as described above showed the characteristics as a p-type transistor element.
The charge mobility was determined from the saturation region of the current-voltage (IV) characteristics of the organic transistor.
Further, the drain current value when the drain bias was set to -50V and the gate bias was set to -50V and 0V was measured, and the on / off ratio of the current was determined.
Further, the produced device was subjected to a moist heat test (after storage at 60 ° C. and an atmosphere of 80% relative humidity for 24 hours), and then the charge mobility and the current on / off ratio were measured in the same manner. The measurement results are shown in Table 1.

(Examples 2 to 10)
In Example 1, instead of using the compound of Exemplified Compound No. 1 in forming the organic semiconductor layer, the compound of Exemplified Compound No. 3 (Example 2), the compound of Exemplified Compound No. 5 (Example 3), and the Exemplified Compound Compound No. 7 (Example 4), Compound No. 12 (Example 5), Compound No. 13 (Example 6), Compound No. 15 (Example 7), Compound No. 16 (Example 8), the compound of Exemplified Compound No. 17 (Example 9), and the compound of Exemplified Compound No. 18 (Example 10) were used, but the organic transistor was produced by the method described in Example 1. did.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, the characteristics of the organic transistor were examined immediately after production and after the moist heat test (after storage for 24 hours in an atmosphere of 60 ° C. and a relative humidity of 80%) by the method described in Example 1, and the results are shown in Table 1. It was shown to.

The compounds used in forming the organic semiconductor layer in the following comparative examples are the compounds of the following formulas (A) to (N).

(Comparative Examples 1 to 4)
In Example 1, instead of using the compound of Exemplified Compound No. 1 in forming the organic semiconductor layer, the compound of the formula (C) (Comparative Example 1), the compound of the formula (D) (Comparative Example 2), the formula ( An organic transistor was produced by the method described in Example 1 except that the compound of E) (Comparative Example 3) and the compound of formula (I) (Comparative Example 4) were used.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, the characteristics of the organic transistor were examined immediately after production and after the moist heat test (after storage for 24 hours in an atmosphere of 60 ° C. and a relative humidity of 80%) by the method described in Example 1, and the results are shown in Table 1. It was shown to.

From Table 1, the organic transistor using the compound represented by the general formula (1) has high charge mobility, a large current on / off ratio, and is excellent in storage stability (moisture and heat resistance). It is clear that.

(Example 11)
_{A thermal oxide film (SiO 2} ) having a thickness of 200 nm was formed on a silicon substrate having a resistivity of 0.02 Ω · cm as a gate electrode. Here, the silicon substrate itself serves as a gate electrode, and the SiO ₂ layer formed on the surface of the silicon substrate serves as a gate insulating layer. When the silicon substrate was heated to 80 ° C. and a chlorobenzene solution (concentration: 0.3% by mass) of the compound of Exemplified Compound No. 4 was applied thereto, chlorobenzene evaporated and the example compound having a thickness of 50 nm was applied. An organic semiconductor layer made of the compound of No. 4 was formed. Further, on this, gold was vapor-deposited using a mask to form a source electrode and a drain electrode. The thickness of the source electrode and the drain electrode was 40 nm, the channel width was 5 mm, and the channel length was 70 μm.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after production and after the moist heat test (after storage at 60 ° C. and 80% relative humidity for 24 hours), and the results are shown in Table 2. It was shown to.

(Examples 12 to 21)
In Example 11, instead of using the compound of Exemplified Compound No. 4 in forming the organic semiconductor layer, the compound of Exemplified Compound No. 6 (Example 12), the compound of Exemplified Compound No. 8 (Example 13), and the Exemplified Compound Compound No. 11 (Example 14), Compound No. 14 (Example 15), Compound No. 15 (Example 16), Compound No. 16 (Example 17), Compound No. 18 (Example 18), the compound of Exemplified Compound No. 20 (Example 19), the compound of Exemplified Compound No. 21 (Example 20), and the compound of Exemplified Compound No. 22 (Example 21). An organic transistor was produced by the method described in Example 11.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after production and after the moist heat test (after storage at 60 ° C. and 80% relative humidity for 24 hours), and the results are shown in Table 2. It was shown to.

(Comparative Examples 5 to 17)
In Example 11, instead of using the compound of Exemplified Compound No. 4 in forming the organic semiconductor layer, the compound of the formula (A) (Comparative Example 5), the compound of the formula (B) (Comparative Example 6), and the formula ( Compound of formula (D) (Comparative Example 7), compound of formula (E) (Comparative Example 8), compound of formula (F) (Comparative Example 9), compound of formula (G) (Comparative Example 10), formula (H) Compound (Comparative Example 11), Compound of Formula (I) (Comparative Example 12), Compound of Formula (J) (Comparative Example 13), Compound of Formula (K) (Comparative Example 14), Compound of Formula (L) An organic transistor was produced by the method described in Example 11 except that the compound of the formula (M) (Comparative Example 16) and the compound of the formula (N) (Comparative Example 17) were used.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after production and after the moist heat test (after storage at 60 ° C. and 80% relative humidity for 24 hours), and the results are shown in Table 2. It was shown to.

From Table 2, the organic transistor using the compound represented by the general formula (1) has high charge mobility, a large current on / off ratio, and is excellent in storage stability (moisture and heat resistance). It is clear that.

(Example 22)
_{A thermal oxide film (SiO 2} ) having a thickness of 200 nm was formed on a silicon substrate having a resistivity of 0.02 Ω · cm as a gate electrode. Here, the silicon substrate itself serves as a gate electrode, and the SiO ₂ layer formed on the surface of the silicon substrate serves as a gate insulating layer.
A coating solution was prepared by dissolving 10 mg of the compound of Exemplified Compound No. 5 and 10 mg of polystyrene (manufactured by Sigma-Aldrich, Mw: 350,000) in 2 g of 1,2-dichlorobenzene.
A silicon substrate is heated to 80 ° C., and this coating liquid is applied onto the silicon substrate to evaporate 1,2-dichlorobenzene. An organic semiconductor consisting of the compound of Exemplified Compound No. 5 having a thickness of 50 nm and polystyrene. A layer was formed.
Further, on this, gold was vapor-deposited using a mask to form a source electrode and a drain electrode. The thickness of the source electrode and the drain electrode was 40 nm, the channel width was 5 mm, and the channel length was 70 μm.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, the characteristics of the organic transistor were examined immediately after production by the method described in Example 1, and the results are shown in Table 3.

(Examples 23 to 29)
In Example 22, instead of using the compound of Exemplified Compound No. 5 in forming the organic semiconductor layer, the compound of Exemplified Compound No. 7 (Example 23), the compound of Exemplified Compound No. 14 (Example 24), and the Exemplified Compound Compound No. 15 (Example 25), Compound No. 17 (Example 26), Compound No. 19 (Example 27), Compound No. 20 (Example 28), Compound No. 22 An organic transistor was produced by the method described in Example 22 except that the compound of (Example 29) was used.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, the characteristics of the organic transistor were examined immediately after production by the method described in Example 1, and the results are shown in Table 3.

(Comparative Examples 18 to 21)
In Example 22, instead of using the compound of Exemplified Compound No. 5 in forming the organic semiconductor layer, the compound of the formula (D) (Comparative Example 18), the compound of the formula (E) (Comparative Example 19), and the formula ( An organic transistor was produced by the method described in Example 20 except that the compound of I) (Comparative Example 20) and the compound of formula (L) (Comparative Example 21) were used.
The produced organic transistor showed characteristics as a p-type transistor element.
Further, the characteristics of the organic transistor were examined immediately after production by the method described in Example 1, and the results are shown in Table 3.

From Table 3, the organic transistor formed by forming the organic semiconductor layer in combination with the compound represented by the general formula (1) and the polymer compound has high charge mobility and a large current on / off ratio. It is clear that In addition, the organic transistor of the above example showed excellent storage stability even in the moist heat test.

The organic transistor of the present invention has high charge mobility, a large current on / off ratio, and is excellent in storage stability (moisture and heat resistance), and is excellent in liquid crystal display element, organic field light emitting element, electronic paper, and various sensors. , RFIDs (radio frequency identification cards) and the like.

11: Substrate 21: Gate electrode 31: Gate insulating layer 41: Drain electrode 51: Organic semiconductor layer 61: Source electrode

12: Substrate 22: Gate electrode 32: Gate insulating layer 42: Drain electrode 52: Organic semiconductor layer 62: Source electrode

13: Substrate 23: Gate electrode 33: Gate insulating layer 43: Drain electrode 53: Organic semiconductor layer 63: Source electrode

14: Substrate 24: Gate electrode 34: Gate insulating layer 44: Drain electrode 54: Organic semiconductor layer 64: Source electrode

Claims (1)

An organic transistor having an organic semiconductor layer, wherein the organic semiconductor layer contains at least one compound selected from the compounds represented by the general formula (1).

(In the formula, X ₁ and X ₂ represent a linear alkyl group having 2 to 12 carbon atoms, and the other represents a hydrogen atom.)

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