JP2011040432A - Organic semiconductor transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor transistor which suppresses deterioration of carrier mobility compared with an organic semiconductor transistor having an organic semiconductor layer using 13,6-N-sulfinyl acetamide pentacene. <P>SOLUTION: An organic semiconductor transistor has: a plurality of electrodes; and an organic semiconductor layer containing at least one kind of fluorene compound expressed by general formula (I). In the general formula (I), R<SB>1</SB>denotes a 1-6C alkyl group. R<SB>2</SB>demotes a 1-8C alkyl group, or a 1-8C alkoxy group. n demotes an integer from 1 to 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic semiconductor transistor.

  Thin film transistors are widely used as display switching elements such as liquid crystal display elements. Conventionally, a thin film transistor is manufactured using amorphous or polycrystalline silicon.

  On the other hand, research on organic semiconductors represented by organic EL (Electro-Luminescence) elements and the like has been actively conducted in recent years. At the same time, research has been reported to replace organic materials with silicon materials and incorporate them into circuits utilizing the characteristics of light weight and flexibility.

  As an organic substance used for such a thin film transistor, a low molecular compound or a high molecular compound is used. As low molecular weight compounds, polyacene compounds such as pentacene and tetracene (for example, refer to Patent Documents 1 to 3) and phthalocyanine compounds such as copper phthalocyanine (for example, refer to Patent Documents 4 and 5) have been proposed.

  Examples of the polymer compound include aromatic oligomers such as sexithiophene (see, for example, Patent Document 6), polymer compounds such as polythiophene, polythienylene vinylene, and poly (p-phenylene vinylene) (for example, Patent Documents 7 to 7). 10 and Non-Patent Document 1).

JP-A-5-55568 JP-A-10-270712 JP 2001-94107 A Japanese Patent Laid-Open No. 5-190877 JP 2000-174277 A JP-A-8-264805 JP-A-8-228034 JP-A-8-228035 Japanese Patent Laid-Open No. 10-125924 Japanese Patent Laid-Open No. 10-190001

Appl.Phys.Lett., 73,108 (1998)

  The subject of this invention is providing the organic-semiconductor transistor by which the fall of charge mobility was suppressed compared with the organic-semiconductor transistor provided with the organic-semiconductor layer using 13, 6-N- sulfinyl acetamide pentacene.

The above problem is solved by the following means. That is,
The invention according to claim 1
A plurality of electrodes;
An organic semiconductor layer containing at least one fluorene compound represented by the following general formula (I);
An organic semiconductor transistor comprising:

[In General Formula (I), R ₁ represents an alkyl group having 1 to 6 carbon atoms. R ₂ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. n represents an integer of 1 to 2. ]

The invention according to claim 2
The plurality of electrodes are a source electrode, a drain electrode and a gate electrode;
Furthermore, an insulating layer is provided,
The gate electrode is provided apart from both the source electrode and the drain electrode;
The organic semiconductor layer is provided in contact with both the source electrode and the drain electrode,
The insulating layer is provided between the organic semiconductor layer and the gate electrode,
2. The organic semiconductor transistor according to claim 1, which is a field effect type.

The invention according to claim 3
The plurality of electrodes are a source electrode, a drain electrode and a gate electrode;
The source electrode and the drain electrode are provided to face each other,
The gate electrode is provided apart from both the source electrode and the drain electrode;
The organic semiconductor layer is provided in contact with both the source electrode and the drain electrode,
And the organic-semiconductor transistor of Claim 1 which is an electrostatic induction type.

According to the first aspect of the present invention, there is provided an organic semiconductor transistor in which a decrease in charge mobility is suppressed as compared with an organic semiconductor transistor having an organic semiconductor layer using 13,6-N-sulfinylacetamidopentacene. The
According to the second aspect of the present invention, there is provided an organic semiconductor transistor in which a decrease in charge mobility is suppressed as compared with an organic semiconductor transistor having an organic semiconductor layer using 13,6-N-sulfinylacetamidopentacene. The
The invention according to claim 3 provides an organic semiconductor transistor in which a decrease in charge mobility is suppressed as compared with an organic semiconductor transistor including an organic semiconductor layer using 13,6-N-sulfinylacetamidopentacene. The

It is the schematic block diagram which showed an example of the layer structure of the organic-semiconductor transistor of this embodiment. It is the schematic block diagram which showed an example of the layer structure of the organic-semiconductor transistor of other embodiment. It is the schematic block diagram which showed an example of the layer structure of the organic-semiconductor transistor of other embodiment. It is the schematic block diagram which showed an example of the layer structure of the organic-semiconductor transistor of other embodiment.

  Hereinafter, this embodiment will be described in detail. In addition, this invention is not restrict | limited by the effect | action and function estimated by this specification.

  The organic semiconductor transistor of this embodiment includes a plurality of electrodes and an organic semiconductor layer containing at least one fluorene compound represented by the following general formula (I).

The fluorene compound represented by the following general formula (I) is superior to 13,6-N-sulfinylacetamidopentacene in terms of charge transportability and solubility in an organic solvent generally used in the production of electronic devices. Therefore, it has a good film forming property. For this reason, it is thought that the organic semiconductor transistor which has a semiconductor layer containing this suppresses the fall of charge mobility.
Further, since the fluorene compound represented by the following general formula (I) is excellent in solubility in an organic solvent, a solution in which the fluorene compound represented by the general formula (I) is dissolved in an organic solvent is used, and the organic compound is obtained by a so-called wet process. A semiconductor layer is formed. Moreover, in the organic semiconductor layer obtained in this way, failures in film formation such as cracks, cracks and chips can be suppressed because of the high solubility of the fluorene compound represented by the general formula (I) in an organic solvent. As a result, it is presumed that the occurrence of defects in the electrical characteristics within the plane is suppressed, or the variation in electrical characteristics within the plane is suppressed. Furthermore, it becomes easy to produce a large area device.

In the compound represented by the general formula (I), thiophene rings are arranged at both ends with dibenzothiophene as the center. As a result of introducing the thiophene ring at both ends, it is presumed that the π-conjugated system extends widely and the charge easily moves and the charge mobility is improved. In addition, as a result of introducing a large number of sulfur atoms having a large ionic radius, it is presumed that charge is easily received and charge injection is improved. From the above, the compound represented by the general formula (I) is a material suitable for the organic semiconductor layer of the transistor.
In the present specification, the “thiophene ring” means a thiophene ring group or a plurality of thiophene rings connected to each other.

  Hereinafter, the fluorene compound represented by the following general formula (I) will be described, and then the organic semiconductor transistor of this embodiment will be described.

In general formula (I), R ₁ represents an alkyl group having 1 to 6 carbon atoms. R ₂ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. n represents an integer of 1 to 2.

In general formula (I), the alkyl group represented by R ₁ is an alkyl group having 1 to 6 carbon atoms (preferably 3 to 6), and specifically includes, for example, a methyl group, an ethyl group, n- A propyl group, an isopropyl group, an n-butyl group, a t-butyl group, a pentyl group, a hexyl group, or the like can be given. The alkyl group represented by R ₁ may be linear or branched.

In general formula (I), the alkyl group represented by R ₂ is an alkyl group having 1 to 8 carbon atoms (preferably 3 to 6), and specifically includes, for example, a methyl group, an ethyl group, n- A propyl group, an isopropyl group, an n-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, or the like can be given. The alkyl group represented by R ₂ may be linear or branched.

In the general formula (I), the alkoxy group represented by R ₂ is an alkoxy group having 1 to 8 carbon atoms (preferably 3 to 6), and specifically includes, for example, a methoxy group, an ethoxy group, n- A propoxy group, an isopropyl group, an n-butoxy group, a t-butoxy group, pentyloxy, or the like can be given. The alkoxy group represented by R ₂ may be linear or branched.

  Hereinafter, although illustrated about the specific example of a fluorene compound shown by general formula (I), it is not limited to these. In addition, the number of “Structure No” indicates the number of an exemplary compound that is a specific example.

Hereinafter, the manufacturing method of the fluorene compound shown by general formula (I) is demonstrated.
The fluorene compound represented by the general formula (I) can be obtained by using, for example, cross-coupling biaryl synthesis. For the cross-coupled biaryl synthesis, a Suzuki reaction, a Kharasch reaction, a Negishi reaction, a Stille reaction, a Grignard reaction, or an Ullmann reaction is used. Specifically, for example, it is synthesized according to the following scheme, but is not limited thereto. Following general formula (IV), in (V), _{R 1} is corresponds to _{R 1} in the general formula (I), _{R 2} may correspond to _{R 2} in the general formula (I), n the general formula ( It corresponds to n in I).

In general formulas (IV) and (V), X and G each independently represent a halogen atom, B (OH) ₂ , the following group 1, the following group 2, or the following group 3.

Examples of the metal, metal catalyst, base, and solvent that may be used in the synthesis reaction include the following.
Examples of the metal include Pd, Cu, Ti, Sn, Ni, or Pt.
Examples of the metal catalyst include metal complexes (for example, Pd (PPh ₃ ) ₄ , Pd (OAc) ₂ , Pd ₂ (dba) ₃ , Pd (PPh ₃ ) ₂ Cl ₂ , Pd (dppf) ₂ Cl ₂ , Pd / C, Ni (acac) ₂ ) and the like. “Dba” represents dibenzylideneacetone and “dppf” represents bis (diphenylphosphino) ferrocene.
Examples of the base include an inorganic base (for example, Na ₂ CO ₃ , K ₂ CO ₃ , Cs ₂ CO ₃ , or Ba (OH) ₂ ), an organic base (for example, NEt ₃ , NH (i-Pr) ₂ ). , NHEt ₂ , NHMe ₂ , NMe ₃ , DBU, DMAP, pyridine, etc.).
The solvent may be any solvent that does not significantly inhibit the reaction. For example, an aromatic hydrocarbon solvent (such as benzene, toluene, xylene, or mesitylene), an ether solvent (such as diethyl ether, tetrahydrofuran, or dioxane). , Acetonitrile, dimethylformamide, dimethyl sulfoxide, methanol, ethanol, isopropyl alcohol, water, PPh ₃ , P (o-Tol) ₃ , P (t-Bu) ₃ , or PEt ₃ .

  The above synthesis reaction is performed, for example, under normal pressure (1 atm) and in an inert gas (for example, nitrogen or argon) atmosphere, but may be performed under pressurized conditions. The reaction temperature of the above synthesis reaction is in the range of 20 ° C. or higher and 300 ° C. or lower, more preferably in the range of 50 ° C. or higher and 180 ° C. or lower. The reaction time for the synthesis reaction may vary depending on the reaction conditions, but may be selected from the range of several minutes to 20 hours.

  In the above reaction, the amount of the metal or metal complex catalyst used is not particularly limited, but is 0.001 mol% or more and 10 mol% or less with respect to the general formula (I), and more preferably 0.8. It is 01 mol% or more and 5.0 mol% or less.

  Also. The amount of the base used is in the range of 0.5 or more and 4.0 or less, more preferably in the range of 1.0 or more and 2.5 or less, with respect to the compound represented by the general formula (I).

  Then, after the above reaction, the reaction solution is poured into water, stirred well, and when the reaction product is a solid (crystal), a crude product is obtained by filtration by suction filtration. On the other hand, when the reaction product is an oily product, a crude product is obtained by extraction with an appropriate solvent such as ethyl acetate or toluene. Thereafter, the resulting crude product is subjected to column purification (column purification using silica gel, alumina, activated clay, activated carbon, etc.), or these adsorbents are added to the solution to adsorb unnecessary components. To purify. When the reaction product is a crystal, it is further purified by recrystallization from an appropriate solvent (for example, hexane, methanol, acetone, ethanol, ethyl acetate, toluene, etc.). Thus, the target fluorene compound is obtained.

<Organic semiconductor transistor>
The organic semiconductor transistor of this embodiment includes a plurality of electrodes and an organic semiconductor layer containing at least one fluorene compound represented by the general formula (I). Other configurations are not particularly limited as long as they correspond to this configuration.
Hereinafter, although it demonstrates in detail, referring a figure, it is not limited to this.

  1, 2, 3 and 4 are cross-sectional views illustrating the configuration of an example of the organic semiconductor transistor of the present embodiment. Here, FIG. 1, FIG. 2 and FIG. 3 show a field effect transistor organic semiconductor transistor. FIG. 4 shows an organic semiconductor transistor of a static induction type (Static Induction Transitor).

The field effect organic semiconductor transistor shown in FIGS. 1, 2, and 3 includes a source electrode 2 and a drain electrode 3 that are spaced apart from each other, and an organic semiconductor layer 4 that is in contact with both the source electrode 2 and the drain electrode 3. A gate electrode 5 spaced from both the source electrode 2 and the drain electrode 3, and an insulating layer 6 provided between the organic semiconductor layer 4 and the gate electrode 5.
A field-effect organic semiconductor transistor is a form of a transistor that is widely used at present, and has advantages such as high-speed switching operation, simplicity of a manufacturing method, and suitability for high integration.

  The field effect organic semiconductor transistor shown in FIGS. 1, 2 and 3 controls the current flowing from the source electrode 2 to the drain electrode 3 by the voltage applied to the gate electrode 5.

  The organic semiconductor transistor shown in FIG. 1 includes a gate electrode 5 on a substrate 1 and further includes an insulating layer 6 on the gate electrode 5. On the insulating layer 6, a source electrode 2 and a drain electrode 3 formed separately are provided. The insulating layer 6 exposed from the source electrode 2 and the drain electrode 3 is covered with the organic semiconductor layer 4.

  In the organic semiconductor transistor shown in FIG. 2, either the source electrode 2 or the drain electrode 3 is formed on the insulating layer 6, and covers the source electrode 2 or the drain electrode 3 and the insulating layer 6 formed on the insulating layer 6. Thus, the organic semiconductor layer 4 is formed, and either the source electrode 2 or the drain electrode 3 that is not formed is formed on the organic semiconductor layer 4 so as to sandwich the organic semiconductor layer 4.

  In the organic semiconductor transistor shown in FIG. 3, the organic semiconductor layer 4 is formed on the insulating layer 6, and the source electrode 2 and the drain electrode 3 are formed on the organic semiconductor layer so as to be separated from each other.

  An electrostatic induction transistor (Static Induction Transitor) shown in FIG. 4 includes a source electrode 2 and a drain electrode 3 which are provided to face each other, an organic semiconductor layer 4 in contact with both the source electrode 2 and the drain electrode 3, and a source And a gate electrode 5 spaced from both the electrode 2 and the drain electrode 3. That is, the source electrode 2, the organic semiconductor layer 4, and the drain electrode 3 are provided in this order on the substrate 1, and a plurality of gate electrodes 5 are provided in the organic semiconductor layer 4. The gate electrode 5 is arranged so as to be parallel to both the source electrode 2 and the drain electrode 3 in the direction from the front to the back of the page, and the gate electrodes 5 are also provided so as to be parallel to each other. Yes.

  In the organic semiconductor transistor element shown in FIGS. 1, 2, 3 and 4, the current flowing from the source electrode 2 to the drain electrode 3 is controlled by the voltage applied to the gate electrode 5.

  The material used for each electrode is a material for injecting charges efficiently, and metals, metal oxides, conductive polymers, carbon, graphite, and the like are used.

  Examples of the metal used for the electrode include magnesium, aluminum, gold, silver, copper, platinum, chromium, tantalum, indium, palladium, lithium, calcium, and alloys thereof. Metal oxides include lithium oxide, magnesium oxide, aluminum oxide, indium tin oxide, tin oxide, indium oxide, zinc oxide, indium zinc indium tin oxide (ITO), tin oxide (NESA), zinc oxide, indium zinc oxide. And the like.

  Examples of the conductive polymer used for the electrode include polyaniline, polythiophene, polythiophene derivatives, polypyrrole, polypyridine, and a complex of polyethylenedioxythiophene and polystyrenesulfonic acid.

In the present embodiment, conductivity means a range of 10 ⁷ Ωcm or less in volume resistivity. On the other hand, the insulating property means a range of 10 ¹⁴ Ωcm or more in volume resistivity.

  The volume resistivity is measured in accordance with JIS-K-6911 (1995) by using a circular electrode (high probe IP UR probe made by Mitsubishi Yuka Co., Ltd .: cylindrical electrode outer diameter Φ16 mm, ring electrode part) Is measured by using a microammeter R8340A manufactured by Advantest and applying a voltage of 100V under an environment of 22 ° C / 55% RH and applying a voltage of 5 sec after application. Thus, the volume resistivity is obtained from the volume resistance.

The difference between the ionization potential of the material used for the drain electrode 3 and the source electrode 2 and the ionization potential of the fluorene compound represented by the general formula (I) used for the organic semiconductor layer 4 is within 1.0 eV from the viewpoint of charge injection characteristics. It is preferable that it is within 0.5 ev.
Considering the difference in ionization potential between these electrodes and the fluorene compound represented by the general formula (I), it is preferable to use Au as the electrode material.

  When a conductive substrate is used, for example, a highly doped silicon substrate can also serve as the gate electrode.

  As a method for forming an electrode, a thin film is formed from the above raw material by a method such as vapor deposition or sputtering, and the thin film is formed by a known photolithography method or a lift-off method. There is a method of forming a resist layer and etching the resist layer. Alternatively, the conductive polymer may be dissolved in a solvent, and this solution may be patterned by ink jet or the like.

  The film thicknesses of the source electrode 2 and the drain electrode 3 are not particularly limited, but are generally preferably in the range of several nm to several hundred μm, more preferably 1 nm to 100 μm, and even more preferably. Is 10 nm or more and 10 μm or less.

  In general, the distance (channel length) from the source electrode 2 to the drain electrode 3 is preferably in the range of several hundred nm to several mm, and more preferably 1 μm to 1 mm.

  As the insulating layer 6, inorganic substances such as silicon dioxide, silicon nitride, tantalum oxide, aluminum oxide, titanium oxide, tantalum oxide, tin oxide, vanadium oxide, barium strontium titanate, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, Polyvinyl chloride resin, cellulose resin, urethane resin, epoxy resin, polystyrene styrene resin, polyvinyl acetate resin, styrene butadiene copolymer, vinyl chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicon Examples thereof include organic insulating polymers such as resins, but are not limited thereto.

Examples of the method for forming an inorganic insulating layer include dry processes such as vacuum deposition, molecular beam epitaxy, ion cluster beam, low energy beam, ion plating, CVD, sputtering, and atmospheric pressure plasma. Furthermore, examples include wet processes such as spray coating, spin coating, blade coating, dip coating, casting, roll coating, bar coating, die coating, air knife, and inkjet. Depending on the material used and the characteristics of the element, it can be selected and employed.
The wet process is preferably used as the method for forming the insulating layer using the organic insulating polymer.

  The film thickness of the insulating layer 6 is not particularly limited, but it is generally preferably in the range of several nm to several hundred μm, more preferably 1 nm to 100 μm, and even more preferably 10 nm. It is 10 μm or less.

  In addition, the interface of the insulating layer 6 in contact with the organic semiconductor layer 4 may be treated with a silane compound such as hexamethyldisilazane, octadecyltrimethoxysilane, octadecyltrichlorosilane, octyltrichlorosilane, or the like. May be rubbed.

  As the substrate 1, silicon single crystal or glass doped with phosphorus or the like at high concentration, glass, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, cellulose resin, urethane resin, epoxy resin, police styrene resin, polyvinyl Examples include, but are not limited to, acetate resins, styrene butadiene copolymers, vinyl chloride-acrylonitrile copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers, plastic substrates such as silicone resins, and the like. .

  In particular, when the organic semiconductor transistor of this embodiment is used in an electronic circuit used in electronic paper, digital paper, or a portable electronic device, it is desirable to use a flexible substrate as the substrate 1. In particular, by using a substrate having a flexural modulus of 1000 MPa or more, a flexible display element drive circuit or electronic circuit is manufactured.

  As a method for forming the organic semiconductor layer 4, various printing methods using a wet process such as a spin coating method, a casting method, a dip coating method, a die coating method, a roll coating method, a bar coating method, and an ink jet method are used.

  As described above, since the fluorene compound represented by the general formula (I) exhibits excellent solubility in an organic solvent, a wet process for forming an organic semiconductor layer using a solution in which these are dissolved is represented by the general formula ( It is suitable as a method for forming an organic semiconductor containing the compound represented by I).

  Examples of the solvent for the coating solution include alcohols such as water, methanol, ethanol, isopropyl alcohol, and butanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexane non, ester solvents such as ethyl acetate and butyl acetate, Hexane, octane, toluene, xylene, ethylbenzene, hydrocarbon solvents such as engineering surfaces, halogenated hydrocarbon solvents such as dichloromethane, chloroform, dichloroethane, tetrachloroethylene, chlorobenzene, o-dichlorobenzene, trichlorobenzene, acetonitrile, propionitrile, Nitrile solvents such as methoxyacetonitrile, glutarodinitrile, benzonitrile, dimethyl sulfoxide, sulfolane, N, N-dimethylformamide, Examples include, but are not limited to, aprotic polar solvents such as N, N-dimethylacetamide and N-methyl-2-pyrrolidone. These solvents may be used alone or in combination of two or more.

  The film thickness of the organic semiconductor layer 4 is not particularly limited, but is generally in the range of several nm to several hundred μm, more preferably 1 nm to 100 μm, and even more preferably 5 nm to 10 μm. It is.

  Further, the organic semiconductor layer 4 may be doped. In addition, both a donor-type dopant and an acceptor-type dopant can be used as the dopatont.

  As the donor dopant, any compound having a function of donating electrons to the organic compound of the organic semiconductor layer 4 is 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, Sm, Eu, Gd, Examples thereof include rare earth metals such as Tb, Dy, Ho, Er, and Yb, and ammonium ions.

As the acceptor dopant, any compound having a function of removing electrons from the organic compound of the organic semiconductor layer 4 is preferably used. Examples of the acceptor dopant include halogen compounds such as Cl ₂ , Br ₂ , I ₂ , ICl, ICl ₃ , and IBr, Lewis acids such as PF ₅ , AsF ₅ , SbF ₅ , BF ₃ , BF ₃ , and SO ₃ , Protons such as HF, HCl, HNO ₃ , H ₂ SO ₄ , organic acids such as acetic acid, formic acid, amino acids, transition metal compounds such as FeCl ₃ , TiCl ₄ , HfCl ₄ , Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ -, electrolyte anions such as sulfonate anion, tetracyanoethylene, 7,7,8,8-tetracyanoquinodimethane, 11,11,12,12- tetracyanoquinodimethane naphthaldehyde 2,6 quinodimethane, 2,5 -Difluoro-7,7,8,8-tetracyanoquinodimethane, tetrafluorotetracyanoquinodimethane, and other organic compounds Is mentioned.

Further, a protective layer may be provided in order to prevent deterioration of the organic semiconductor transistor due to moisture or oxygen. Specific examples of the protective layer material include metals such as In, Sn, Pb, Au, Cu, Ag, and Al, metal oxides such as MgO, SiO ₂ , and TiO ₂ , polyethylene resins, polyurea resins, and polyimide resins. A vacuum deposition method, a sputtering method, a plasma polymerization method, a CVD (Chemical Vapor Deposition) method, and a coating method are applied to the formation of the protective layer including a resin.

  In the organic semiconductor transistor of this embodiment, a fluorene compound represented by the general formula (I) is used for the organic semiconductor layer. The fluorene compound represented by the general formula (I) exhibits excellent solubility in organic solvents that are generally used in the production of electronic devices. Therefore, when the fluorene compound represented by the general formula (I) is applied to the organic semiconductor layer, the organic semiconductor layer can be manufactured by a wet process. As a result, the organic semiconductor layer can be formed with an inexpensive apparatus as compared with a layer forming method such as sputtering, and the area of the device can be easily increased. Furthermore, in the organic semiconductor layer containing the fluorene compound represented by the general formula (I) formed by the wet process, failures in film formation such as cracks, cracks, and chips can be suppressed, resulting in in-plane electrical property defects and Variability is suppressed.

  When an electronic device using the organic semiconductor transistor of this embodiment is manufactured, it can be used as a configuration (semiconductor device) in which one or more organic semiconductor transistors of this embodiment are mounted on a substrate. A desired electronic device is manufactured by further combining other elements, circuits, and the like with this semiconductor device.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

For identification of the target product, 1H-NMR spectrum (1H-NMR, solvent: CDCl ₃ , manufactured by VARIAN, UNITY-300, 300 MHz) and IR spectrum (Fourier transform infrared spectrophotometer (KBr tablet method) HORIBA, Ltd., FT-730, resolution 4 cm ⁻¹ )) was used.

[Synthesis Example 1]
-Synthesis of Exemplified Compound 24-
According to the following scheme, tetrakis (triphenylphosphine) was added to a mixture of 1-bromo-4-n-octylbenzene (25.0 g), 2-thiopheneboronic acid (10.8 g), and tetrahydrofuran (100 ml) under a nitrogen atmosphere. ) Palladium (2.3 g) and 2N aqueous sodium carbonate solution (10 ml) were added and refluxed for 10 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (hexane) to obtain Intermediate 1 (26.2 g).

  Next, according to the following scheme, intermediate 1 (26.2 g) was dissolved in N, N-dimethylformamide (100 ml), N-bromosuccinimide (17.5 g) was added, and the mixture was stirred for 18 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure to obtain Intermediate 2 (28.8 g).

  Next, according to the following scheme, tetrakis (triphenylphosphine) was added to a mixture of intermediate 2 (5.49 g), 9,9-dihexylfluorene-2, 7-diboronic acid (3.0 g), and tetrahydrofuran (100 ml). Palladium (2.3 g) and 2N aqueous sodium carbonate solution (5 ml) were added, and the mixture was refluxed for 8 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Next, after drying over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (hexane) to obtain 2.5 g of [Exemplary Compound 24].

The melting point of Example Compound 24 obtained was 78 to 80 ° C. The obtained [Exemplary Compound 24] was identified by ¹ H-NMR spectrum (1H-NMR, solvent: CDCl ₃ , Varian Inc., UNITY-300, 300 MHz) and IR spectrum (Fourier by KBr method). A conversion infrared spectrophotometer (Horiba, Ltd., FT-730, resolution: 4 cm ⁻¹ ) was used.
The infrared absorption spectrum (KBr tablet method) is as follows.
IR (cm ⁻¹ ); 792, 863, 1072, 1400, 1444, 1469, 1592, 2854, 2921,
¹ H-NMR (CDCl ₃ ) is as follows.
_{^{NMR (1 H, CDCl 3)}} : 0.59-1.79 (52H), 1.95-2.16 (4H), 2.59-2.78 (4H), 7.10-7.38 ( 8H), 7.45-7.78 (10H)

[Synthesis Example 2]
-Synthesis of Exemplified Compound 26-
Intermediate 2 (15.0 g) was obtained in the same manner as in Synthesis Example 1, and then intermediate 2 (15.0 g) and 2-thiopheneboronic acid (6.0 g) under a nitrogen atmosphere according to the following scheme. Tetrakis (triphenylphosphine) palladium (0.9 g) and 2N aqueous sodium carbonate solution (7 ml) were added to a mixture of tetrahydrofuran (100 ml), and the mixture was refluxed for 30 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (hexane) to obtain Intermediate 3 (7.8 g).

  Next, according to the following scheme, intermediate 3 (7.8 g) was dissolved in N, N-dimethylformamide (100 ml), N-bromosuccinimide (4.1 g) was added, and the mixture was stirred for 18 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure to obtain Intermediate 4 (9.2 g).

  Next, according to the following scheme, tetrakis (triphenylphosphine) palladium was added to a mixture of intermediate 4 (9.2 g), 9,9-dihexylfluorene-2, 7-diboronic acid (4.2 g), and tetrahydrofuran 100 ml). (0.6 g) 2N aqueous sodium carbonate solution (7 ml) was added and refluxed for 20 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Next, after drying over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (hexane) to obtain 1.5 g of [Exemplary Compound 26].

The melting point of Example Compound 26 obtained was 117 to 118 ° C. In addition, for identification of the obtained [Exemplary Compound 26], a ¹ H-NMR spectrum and an infrared absorption spectrum were used as in Synthesis Example 1.
The infrared absorption spectrum (KBr tablet method) is as follows.
IR (cm ⁻¹ ); 792, 863, 1072, 1400, 1444, 1469, 1592, 2854, 2921,
¹ H-NMR (CDCl ₃ ) is as follows.
_{^{NMR (1 H, CDCl 3)}} : 0.59-1.45 (52H), 1.89-2.08 (4H), 2.56-2.78 (4H), 7.10-7.38 ( 11H), 7.45-7.78 (11H)

[Synthesis Example 3]
-Synthesis of Exemplified Compound 25-
According to the following scheme, 4-nitrophenol (25.0 g), potassium carbonate (21.7 g), and tetrabutylammonium bromide (2.3 g) were dissolved in methyl ethyl ketone (100 ml) in a nitrogen atmosphere, and then 1-bromo A mixed solution of octane (30.7 g) dissolved in methyl ethyl ketone (15 ml) is added dropwise. After stirring for 5 hours, the organic phase was thoroughly washed with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (hexane) to obtain Intermediate 5 (42.5 g).

  Next, according to the following scheme, tetrakis (triphenylphosphine) palladium (1) was added to a mixture of intermediate 5 (15.0 g), 2-thiopheneboronic acid (7.3 g), and tetrahydrofuran (100 ml) under a nitrogen atmosphere. 0.2 g) 2N aqueous sodium carbonate solution (7 ml) was added and refluxed for 8 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (hexane) to obtain Intermediate 6 (9.1 g).

  Next, according to the following scheme, intermediate 6 (9.1 g) was dissolved in N, N-dimethylformamide (150 ml), N-bromosuccinimide (6.1 g) was added, and the mixture was stirred for 18 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure to obtain Intermediate 7 (8.1 g).

  Next, according to the following scheme, tetrakis (triphenylphosphine) was added to a mixture of intermediate 7 (5.7 g), 9,9-dihexylfluorene-2, 7-diboronic acid (3.0 g), and tetrahydrofuran (100 ml). Palladium (1.2 g) and 2N aqueous sodium carbonate solution (5 ml) were added, and the mixture was refluxed for 8 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Next, after drying over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, separated by silica gel column chromatography (hexane: toluene = 3: 1), and recrystallized from isopropyl alcohol to obtain 2.7 g of [Exemplary Compound 25]. It was.

The obtained Exemplified Compound 25 had a melting point of 96 to 97 ° C. In addition, for identification of the obtained [Exemplary Compound 25], a ¹ H-NMR spectrum and an IR spectrum were used as in Synthesis Example 1.
The infrared absorption spectrum (KBr tablet method) is as follows.
IR (cm ⁻¹ ); 798, 833, 1465, 2850, 2952
¹ H-NMR (CDCl ₃ ) is as follows.
_{^{NMR (1 H, CDCl 3)}} : 0.59-1.55 (48H), 1.62-1.78 (4H), 1.91-2.08 (4H), 3.85-3.98 ( 4H), 6.79-6.92 (4H), 7.14 (2H), 7.26 (2H), 7.42-7.76 (10H)

[Synthesis Example 4]
-Synthesis of Exemplified Compound 27-
In the same manner as in Synthesis Example 3, Intermediate 7 (10.0 g) was obtained, and then, according to the following scheme, Intermediate 7 (10.0 g), 2-thiopheneboronic acid (3.8 g) was added under a nitrogen atmosphere. Tetrakis (triphenylphosphine) palladium (0.6 g) and 2N aqueous sodium carbonate solution (7 ml) were added to a mixture of tetrahydrofuran (100 ml), and the mixture was refluxed for 50 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, and the residue was separated by silica gel column chromatography (toluene) to obtain Intermediate 8 (7.9 g).

  Next, according to the following scheme, intermediate 8 (7.9 g) was dissolved in N, N-dimethylformamide (300 ml), N-bromosuccinimide (3.4 g) was added, and the mixture was stirred for 18 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Subsequently, after drying with anhydrous sodium sulfate, the solvent was distilled off under reduced pressure to obtain Intermediate 9 (5.6 g).

  Next, according to the following scheme, tetrakis (triphenylphosphine) was added to a mixture of intermediate 9 (5.6 g), 9,9-dihexylfluorene-2, 7-diboronic acid (3.0 g), and tetrahydrofuran (100 ml). Palladium (1.2 g) and 2N aqueous sodium carbonate solution (5 ml) were added and refluxed for 12 hours. After the reaction, extraction with toluene was performed, and the organic phase was washed thoroughly with pure water. Next, after drying over anhydrous sodium sulfate, the solvent was distilled off under reduced pressure, separated by silica gel column chromatography (toluene), and recrystallized with a mixed solvent of isopropyl alcohol and toluene to obtain 3.4 g of [Exemplary Compound 27]. .

The melting point of Example Compound 27 obtained was 140 to 141 ° C. The obtained [Display compound 27] was identified using ¹ H-NMR spectrum and IR spectrum as in Synthesis Example 1.
The infrared absorption spectrum (KBr tablet method) is as follows.
IR (cm ⁻¹ ); 609, 809, 1334, 1421, 2850, 2954
¹ H-NMR (CDCl ₃ ) is as follows.
_{^{NMR (1 H, CDCl 3)}} : 0.59-1.58 (48H), 1.72-1.85 (4H), 1.91-2.10 (4H), 3.85-4.01 ( 4H), 6.81-6.98 (4H), 7.14-7.20 (6H), 7.21-7.38 (2H), 7.42-7.76 (10H)

[Example 1]
A silicon substrate having an electrical resistivity of 7 × 10 ⁻³ Ω · cm also served as a gate electrode, and a thermal SiO ₂ film having a thickness of 200 nm was formed thereon to form an insulating film. Next, the silicon substrate on which the insulating film was formed was subjected to ultrasonic cleaning for 5 minutes in acetone for electronic industry, ultrasonic cleaning for 5 minutes in 2-propanol for electronic industry, and dried with dry nitrogen, and then UV. -Ozone irradiation was performed for 15 minutes to clean the surface of the insulating film. Thereafter, the silicon substrate on which the insulating film was formed was exposed to the vapor of 1,1,1,3,3,3-hexamethylsidirazan (manufactured by Aldrich) and then dried with dry nitrogen.
Next, exemplary compound 24 was dissolved in 0.4% by mass in toluene for electronic industry, and this solution was applied on the cleaned silicon substrate (insulating film) by spin coating (20 seconds at 2000 rpm). After drying, the organic semiconductor layer was formed by heating at 100 ° C. for 1 minute in a nitrogen atmosphere. The thickness of the obtained organic semiconductor layer was 85 nm.
Next, on the organic semiconductor layer, gold (Au) is deposited in a thickness of 60 nm by vacuum deposition (vacuum degree 2 × 10 ⁻⁴ Pa) using a metal mask to form a source electrode and a drain electrode. Thus, an organic semiconductor transistor was produced. The channel length from the source electrode to the drain electrode was 1.5 mm and the channel width was 50 μm.
The organic semiconductor transistor fabricated as described above exhibited characteristics as a p-type transistor.

<Measurement of charge mobility>
For the transistor immediately after fabrication, the charge mobility was determined from the saturation region of the current-voltage characteristics. Further, the transistor was stored at 25 ° C., and after one month, the transistor characteristics were evaluated again and the charge mobility was measured. The results are shown in Table 1.

<Film forming properties>
Generation of defects such as cracks, cracks and chips on the surface of the formed organic semiconductor layer was observed with an optical microscope in a range of 1 mm × 1 mm. The results are shown in Table 1. The evaluation criteria are as follows. In addition, the film formability when the solvent was changed from toluene to tetrahydrofuran was also evaluated.
-Evaluation criteria for coating properties-
Judgment was made using a magnifying glass, and evaluation was performed based on the following evaluation criteria.
○: Covered entirely with film, good △: Partially not covered with film ×: Many parts not covered with film

[Examples 2 and 3]
An organic semiconductor transistor was produced in the same manner as in Example 1 except that the exemplified compound 26, the exemplified compound 25, and the exemplified compound 27 were used instead of the exemplified compound 24 used for forming the organic semiconductor layer in the example 1. The obtained organic semiconductor transistor was evaluated in the same manner as in Example 1.

[Comparative Examples 1 and 2]
In Example 1, instead of Exemplified Compound 16, 13,6-N-sulfinylacetamidopentacene (manufactured by Aldrich) was used, and the operation was performed in the same manner as in Example 1 except that the heating temperature was 160 ° C. A semiconductor transistor was fabricated and used as Comparative Example 1.

  Further, Comparative Example 1 except that poly (3-hexylthiophene) (manufactured by Aldrich) was used in place of 13,6-N-sulfinylacetamidopentacene used in Comparative Example 1 and the solvent was changed to chloroform. An organic semiconductor transistor was produced in the same manner as Comparative Example 2.

  The organic semiconductor transistors of Comparative Examples 1 and 2 were evaluated in the same manner as in Example 1. The results are shown in Table 1.

From Table 1 above, the organic semiconductor transistor of the example has a higher charge mobility immediately after production than the organic semiconductor transistor of the comparative example, and the decrease in charge mobility is suppressed even after one month of production. Recognize.
Moreover, it turns out that the organic-semiconductor layer of an Example is excellent in film forming property compared with the organic-semiconductor layer of a comparative example, and generation | occurrence | production of defects, such as a crack, is suppressed.

1 substrate 2 source electrode 3 drain electrode 4 organic semiconductor layer 5 gate electrode 6 insulating layer

Claims (3)

A plurality of electrodes;
An organic semiconductor layer containing at least one fluorene compound represented by the following general formula (I);
An organic semiconductor transistor comprising:
[In General Formula (I), R ₁ represents an alkyl group having 1 to 6 carbon atoms. R ₂ represents an alkyl group having 1 to 8 carbon atoms or an alkoxy group having 1 to 8 carbon atoms. n represents an integer of 1 to 2. ] The plurality of electrodes are a source electrode, a drain electrode and a gate electrode;
Furthermore, an insulating layer is provided,
The gate electrode is provided apart from both the source electrode and the drain electrode;
The organic semiconductor layer is provided in contact with both the source electrode and the drain electrode,
The insulating layer is provided between the organic semiconductor layer and the gate electrode,
2. The organic semiconductor transistor according to claim 1, which is a field effect type. The plurality of electrodes are a source electrode, a drain electrode and a gate electrode;
The source electrode and the drain electrode are provided to face each other,
The gate electrode is provided apart from both the source electrode and the drain electrode;
The organic semiconductor layer is provided in contact with both the source electrode and the drain electrode,
And the organic-semiconductor transistor of Claim 1 which is an electrostatic induction type.