JP7144210B2 - organic transistor - Google Patents

Description

The present invention relates to organic transistors. More particularly, it relates to an organic transistor using a specific organic compound for an organic semiconductor layer.

2. Description of the Related Art Conventionally, thin film transistors (TFTs) using amorphous silicon or polycrystalline silicon have been widely used as switching elements for flat panel displays such as liquid crystal display devices. However, the CVD apparatus used to fabricate these thin film transistors using silicon is expensive, and the fabrication of large-sized thin film transistor elements is accompanied by an increase in manufacturing costs. In addition, since the deposition of amorphous silicon and polycrystalline silicon is carried out at high temperatures, there is a drawback in that plastic materials, which are lightweight and flexible but poor in heat resistance, cannot be used as substrates. .
In order to solve the above problems, an organic transistor (also referred to as an organic thin film transistor or organic TFT) using an organic compound as 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 an organic semiconductor layer, for example, a vacuum deposition method and a coating method are known, and according to these film formation methods, it is possible to easily 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 becomes possible to use plastic materials for the substrate, making it possible to apply it to flexible display elements and its practical use. Expectations are high for the change.

A practical organic transistor should have properties such as high charge mobility and a large current on/off ratio. The term "on/off ratio" here means the ratio of the current between the source and drain electrodes when the organic transistor is on to the current between the source and drain electrodes when the organic transistor is off. do. Furthermore, excellent storage stability is required for practical use of organic transistors.

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

As a solution to these drawbacks, for example, an organic transistor using the compounds of the formulas (A) to (D) in the organic semiconductor layer has been proposed (Patent Document 1).

Further, for example, a method for producing compounds of formulas (E) to (H) is disclosed, and the compounds produced by the method are known to be useful as materials for organic transistors (Patent Document 2). .

Further, for example, an organic transistor is known in which a compound having an aryl group and an alkoxyalkyl group as substituents, such as the compound of formula (I), is used for an organic semiconductor layer (Patent Document 3).

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

Further, for example, an organic transistor using a compound having a branched alkyl group, such as the compound of formula (L), for an organic semiconductor layer has been proposed (Patent Document 5).

Organic transistors using the compounds of formula (B), formula (F), formula (I), and formula (K) as organic semiconductors have relatively high charge mobility, but have poor storage stability (moisture and heat resistance). It has been found.
In addition, it was found that the charge mobility of the organic transistor using the compounds of the formulas (A), (E), (H) to (J), and (L) for the organic semiconductor layer is low. Furthermore, it was found that the compounds of formula (H), formula (I), formula (K), and formula (L) also have problems in storage stability (resistance to moist heat).
At present, there is a demand for the development of further improved organic transistors for practical use.

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

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

Up to now, proposals have been made for organic transistors using various organic compounds in the organic semiconductor layer, but it is difficult to say that all of them have sufficiently satisfactory characteristics for practical use. .
In view of the above, it is an object of the present invention to provide an organic transistor that has high charge mobility, a large current on/off ratio, and excellent storage stability (resistance to moist heat).

In order to solve the above-mentioned problems, the present inventors have made intensive studies and 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 a charge transfer The present inventors have found that it has a high degree of resistance, a large current on/off ratio, and excellent storage stability (moisture and heat resistance), and completed the present invention.

〔式中、Ｘ_１およびＸ_２は、一方が水素原子、アリール基、または式(ａ)で表される基であり、他方が水素原子を表し、Ｘ_３およびＸ_４は、一方が水素原子、アリール基、または式(ａ)で表される基であり、他方が水素原子を表す(但し、Ｘ_１～Ｘ_４の少なくとも一つは式(ａ)で表される基を表す)

(式(ａ)中、ｎは２～１０の整数を表し、Ｒは環状のアルキル基を表す)〕
That is, the present invention
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, one of X ₁ and X ₂ is a hydrogen atom, an aryl group, or a group represented by formula (a), the other represents a hydrogen atom, and one of X ₃ and X ₄ is a hydrogen atom. , an aryl group, or a group represented by formula (a), and the other represents a hydrogen atom (provided that at least one of X ₁ to X ₄ represents a group represented by formula (a))

(In formula (a), n represents an integer of 2 to 10, and R represents a cyclic alkyl group)]

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

1 is a schematic cross-sectional view of an organic transistor of the present invention; FIG. 1 is a schematic cross-sectional view of an organic transistor of the present invention; FIG. 1 is a schematic cross-sectional view of an organic transistor of the present invention; FIG. 1 is a schematic cross-sectional view of an organic transistor of the present invention; FIG.

〔式中、Ｘ_１およびＸ_２は、一方が水素原子、アリール基、または式(ａ)で表される基であり、他方が水素原子を表し、Ｘ_３およびＸ_４は、一方が水素原子、アリール基、または式(ａ)で表される基であり、他方が水素原子を表す(但し、Ｘ_１～Ｘ_４の少なくとも一つは式(ａ)で表される基を表す)

(式（ａ）中、ｎは２～１０の整数を表し、Ｒは環状のアルキル基を表す)〕
The present invention will be described in detail below.
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, one of X ₁ and X ₂ is a hydrogen atom, an aryl group, or a group represented by formula (a), the other represents a hydrogen atom, and one of X ₃ and X ₄ is a hydrogen atom. , an aryl group, or a group represented by formula (a), and the other represents a hydrogen atom (provided that at least one of X ₁ to X ₄ represents a group represented by formula (a))

(In formula (a), n represents an integer of 2 to 10, and R represents a cyclic alkyl group)]

(式（ａ）中、ｎは２～１０の整数を表し、Ｒは環状のアルキル基を表す) One of X ₁ and X ₂ in the compound represented by general formula (1) is a hydrogen atom, an aryl group, or a group represented by formula (a), and the other represents a hydrogen atom. One of X3 and _X4 is a hydrogen atom, an aryl group, or a group represented by formula ₍ a), and the other represents a hydrogen atom. At least one of X ₁ to X ₄ represents a group represented by formula (a).

(In formula (a), n represents an integer of 2 to 10, and R represents a cyclic alkyl group)

In the compound represented by general formula (1), more preferably X ₁ and X ₄ are hydrogen atoms, and X ₂ and X ₃ are hydrogen atoms, aryl groups, or groups represented by formula (a) (provided that at least one of X ₂ and X ₃ represents a group represented by formula (a)).
In the compound represented by general formula ( ₁ ), another more preferred example is that X2 and X3 _are hydrogen atoms _, and X1 and _X4 are hydrogen atoms, aryl groups, or (provided that at least one of X ₁ and X ₄ represents a group represented by formula (a)).

The aryl groups of substituents X ₁ to X ₄ in the compound represented by general formula (1) preferably represent substituted or unsubstituted aryl groups having 4 to 20 carbon atoms.
In the present specification, the aryl group represents, for example, carbocyclic aromatic groups such as phenyl group and naphthyl group, and heterocyclic aromatic groups such as furyl group, thienyl group and pyridyl group.
In addition, the aryl group may have a substituent, and examples of such substituents include halogen atoms, linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms, linear, branched or cyclic alkyl groups having 1 to 20 carbon atoms. A cyclic alkoxy group, or an aryl group optionally substituted with the above halogen atom, alkyl group, or alkoxy group having 4 to 20 carbon atoms may be mentioned. The aryl group may be monosubstituted or polysubstituted with these substituents.

Specific examples of the aryl groups of the substituents X ₁ to X ₄ in the compound represented by the general formula (1) include a phenyl group, a 2-methylphenyl group, a 3-methylphenyl group, a 4-methylphenyl group, 3-ethylphenyl group, 4-ethylphenyl group, 2-n-propylphenyl group, 3-n-propylphenyl group, 4-n-propylphenyl group, 4-isopropylphenyl group, 3-n-butylphenyl group, 4-n-butylphenyl group, 4-isobutylphenyl group, 4-tert-butylphenyl group, 2-n-pentylphenyl group, 3-n-pentylphenyl group, 4-n-pentylphenyl group, 4-isopentyl phenyl group, 4-tert-pentylphenyl group, 3-n-hexylphenyl group, 4-n-hexylphenyl group, 4-cyclohexylphenyl group, 3-n-heptylphenyl group, 4-n-heptylphenyl group, 2 -n-octylphenyl group, 3-n-octylphenyl group, 4-n-octylphenyl group, 3-n-nonylphenyl group, 4-n-nonylphenyl group, 3-n-decylphenyl group, 4-n -decylphenyl group, 4-n-undecylphenyl group, 3-n-dodecylphenyl group, 4-n-dodecylphenyl group, 4-n-tetradecylphenyl group, 2,3-dimethylphenyl group, 2,4 -dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 3,4,5-trimethylphenyl group, 2,3 , 5,6-tetramethylphenyl group, 5-indanyl group, 1,2,3,4-tetrahydro-5-naphthyl group, 1,2,3,4-tetrahydro-6-naphthyl group,

2-methoxyphenyl group, 3-methoxyphenyl group, 4-methoxyphenyl group, 3-ethoxyphenyl group, 4-ethoxyphenyl group, 4-n-propoxyphenyl group, 4-isopropoxyphenyl group, 2-n-butoxy phenyl group, 3-n-butoxyphenyl group, 4-n-butoxyphenyl group, 4-isobutoxyphenyl group, 4-n-pentyloxyphenyl group, 2-n-hexyloxyphenyl group, 3-n-hexyloxy Phenyl group, 4-n-hexyloxyphenyl group, 4-cyclohexyloxyphenyl group, 4-n-heptyloxyphenyl group, 3-n-octyloxyphenyl group, 4-n-octyloxyphenyl group, 4-n- nonyloxyphenyl group, 4-n-decyloxyphenyl group, 4-n-undecyloxyphenyl group, 4-n-dodecyloxyphenyl group, 4-n-tetradecyloxyphenyl group, 2,3-dimethoxyphenyl group , 2,4-dimethoxyphenyl group, 2,5-dimethoxyphenyl group, 3,4-dimethoxyphenyl group, 3,5-dimethoxyphenyl group, 3,5-diethoxyphenyl group, 2-methoxy-4-methylphenyl group, 2-methoxy-5-methylphenyl group, 2-methyl-4-methoxyphenyl group, 3-methyl-4-methoxyphenyl group, 3-methyl-5-methoxyphenyl group,
2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 4-bromophenyl group, 3-trifluoromethylphenyl group, 4-tri fluoromethylphenyl group, 3-trifluoromethyloxyphenyl group, 4-trifluoromethyloxyphenyl group, 2,4-difluorophenyl group, 2,4-dichlorophenyl group, 3,4-difluorophenyl group, 3,4- dichlorophenyl group, 3,5-difluorophenyl group, 3,5-dichlorophenyl group, 3,4,5-trifluorophenyl group, 2-methyl-4-chlorophenyl group, 2-chloro-4-methylphenyl group, 3- chloro-4-methylphenyl group, 2-chloro-4-methoxyphenyl group, 3-methoxy-4-fluorophenyl group, 3-methoxy-4-chlorophenyl group, 3-fluoro-4-methoxyphenyl group, 2,3 , 4,5,6-pentafluorophenyl group, 4-phenylphenyl group, 3-phenylphenyl group, 4-(4'-methylphenyl)phenyl group, 4-(4'-methoxyphenyl)phenyl group, 1- naphthyl group, 2-naphthyl group, 4-methyl-1-naphthyl group, 4-ethoxy-1-naphthyl group, 6-n-butyl-2-naphthyl group, 6-methoxy-2-naphthyl group, 7-ethoxy- 2-naphthyl group, 1-anthracenyl group, 2-anthracenyl group, 9-anthracenyl group, 2-tetracenyl group, 2-fluorenyl group, 9,9-dimethyl-2-fluorenyl group, 9,9-di-n-propyl -2-fluorenyl group, 2-furyl group, 5-n-butyl-2-furyl group, 5-n-hexyl-2-furyl group, 5-n-octyl-2-furyl group, 2-thienyl group, 5 -n-propyl-2-thienyl group, 5-n-butyl-2-thienyl group, 5-n-hexyl-2-thienyl group, 5-n-octyl-2-thienyl group, 5-n-decyl-2 -thienyl group, 5-n-tridecyl-2-thienyl group, 5-phenyl-2-thienyl group, 5-(2'-thienyl)-2-thienyl group, 5-(5'-n-butyl-2' -thienyl)-2-thienyl group, 5-(5'-n-hexyl-2'-thienyl)-2-thienyl group, 5-(5'-n-decyl-2'-thienyl)-2-thienyl group , 3-thienyl group, 2-pyridyl group, 3-pyridyl group, and 4-pyridyl group. Wear.

In the group represented by the formula (a) of the substituents X ₁ to X ₄ in the compound represented by the general formula (1), n represents an integer of 2 to 10, preferably 2, 4, 6, 8 , 10, more preferably 2, 4, 6.
In the group represented by formula (a), R represents a cyclic alkyl group, preferably a cyclic alkyl group having 3 to 10 carbon atoms, more preferably a cyclic alkyl group having 5 to 7 carbon atoms. represents

Specific examples of R in the group represented by formula (a) include, for example, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-n-propylhexyl group, 4-n-butylhexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group and other cyclic alkyl groups.

〔式中、Ｘ_１２およびＸ_１３はそれぞれ独立に、水素原子、アリール基、または式（ａ）で表される基を表し、少なくとも一つは、式（ａ）で表される基を表す〕

〔式中、Ｘ_２１およびＸ_２４はそれぞれ独立に、水素原子、アリール基、または式（ａ）で表される基を表し、少なくとも一つは、式（ａ）で表される基を表す〕 The compound represented by general formula (1) is preferably a compound represented by general formula (1-a) to general formula (1-d), more preferably general formula (1-a) and It is a compound represented by the general formula (1-b).

[Wherein, X ₁₂ and X ₁₃ each independently represent a hydrogen atom, an aryl group, or a group represented by formula (a), and at least one represents a group represented by formula (a)]

[Wherein, X ₂₁ and X ₂₄ each independently represent a hydrogen atom, an aryl group, or a group represented by formula (a), and at least one represents a group represented by formula (a)]

〔式中、Ｘ_３２およびＸ_３４は、一方はアリール基を表し、他方は式（ａ）で表される基を表す〕

〔式中、Ｘ_４１およびＸ_４３は、一方はアリール基を表し、他方は式（ａ）で表される基を表す〕

[In the formula, one of X ₃₂ and X ₃₄ represents an aryl group and the other represents a group represented by formula (a)]

[In the formula, one of X ₄₁ and X ₄₃ represents an aryl group and the other represents a group represented by formula (a)]

In general formulas (1-a) to (1-d), the aryl groups represented by substituents X ₁₂ , X ₁₃ , X ₂₁ , X ₂₄ , X ₃₂ , X ₃₄ , X ₄₁ and X ₄₃ , and the group represented by formula (a) have the same meanings as the aryl groups listed for X ₁ to X ₄ in general formula (1) and the group represented by formula (a).

an aryl group represented by substituents X ₁₂ , X ₁₃ , X ₂₁ , X ₂₄ , X ₃₂ , X ₃₄ , X ₄₁ and X ₄₃ in general formulas (1-a) to (1-d), and Specific examples of the group represented by formula (a) include the aryl groups listed for X ₁ to X ₄ in general formula (1) and the groups represented by formula (a).

Specific examples of the compound represented by 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, added to the compound represented by the general formula (2) or (3) with an acid (for example, an alkylsulfone such as methanesulfonic acid or trifluoromethanesulfonic acid). acid), if desired, in the presence of a dehydrating agent (e.g., phosphorus pentoxide), and then reacting the product with a base (e.g., pyridine, quinoline) [e.g., Macromolecules , 26, 7144 (1993) and J. Mater. Chem., 9, 2095 (1999)].

〔式中、Ｘ_１ ～Ｘ_４は一般式(１)の場合と同じ意味を表す〕

[In the formula, X ₁ to X ₄ have the same meanings as in general formula (1)]

In addition, the compound represented by the general formula (1) according to the present invention may optionally be produced in a form that forms a solvate with the solvent used (for example, an aromatic hydrocarbon solvent such as toluene). However, in the organic transistor of the present invention, not only the non-solvate 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 in an organic transistor, a purification method such as a recrystallization method, a column chromatography method, a sublimation purification method, or a compound whose purity is increased by using these methods in combination. is preferred.

The organic transistor of the present invention is characterized by containing at least one compound represented by the general formula (1) in the organic semiconductor layer. It is possible to provide an organic transistor having a large on/off ratio and excellent storage stability.
The compound represented by general formula (1) in the organic semiconductor layer may be in an amorphous or crystalline form, more preferably in a crystalline form.
The crystal may be in a single crystal state or may be in a polycrystalline state.

An organic transistor usually comprises a source electrode, a drain electrode, a gate electrode, a gate insulating layer, and an organic semiconductor layer. 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 embodiment 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 61 and a drain electrode 61 are formed thereon at predetermined intervals. 41 is formed, and an organic semiconductor layer 51 is laminated thereon (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 thereon. , and further thereon, a source electrode 62 and a drain electrode 42 are formed at predetermined intervals (bottom-gate/top-contact structure).

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

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

In the organic transistor having such a structure, the organic semiconductor layer forms the channel region, and the current flowing between the source electrode and the drain electrode is controlled by the voltage applied to the gate electrode to turn on/off the transistor. Operate.
Furthermore, the organic transistor of the present invention can 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 substrates, etc. can be used. . Furthermore, a composite substrate in which these are combined can also be used, and it may be in the form of a single-layer structure or a multilayer structure.

Examples of plastic substrates include polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyetherimide, polyether ether ketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, triacetyl cellulose, and cellulose acetate propionate. substrates.
When a conductive substrate such as silicon is used as the substrate, the substrate can also serve as the gate electrode.

In the organic transistor of the present invention, materials used for the source electrode, the drain electrode, and the gate electrode are not particularly limited, and any conductive material can be used.

Examples of electrode materials include indium tin oxide (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 , chromium/molybdenum alloys, aluminum/lithium alloys, aluminum/scandium/lithium alloys, sodium/potassium alloys and other metals and alloys, as well as fluorine-doped zinc oxide, silicon single crystals with improved conductivity, polycrystalline silicon, Examples include silicon-based materials such as amorphous silicon, carbon materials such as carbon black, graphite, and glassy carbon. It is an improved silicon-based material and carbon material. These can be used in various forms such as bulk, flaky and fine particles.

In addition, as an electrode material, a conductive polymer whose conductivity is improved by doping treatment (for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid complex, etc.) is also preferably used.
One of these electrode materials may be used alone, or two or more of them may be used in combination.
Among the electrode materials listed above, the source electrode and the drain electrode preferably have a low electrical resistance at 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 using a method such as vapor deposition or sputtering, and patterned into a desired shape by lithography or etching. can.
In the case of forming an electrode using a conductive polymer or conductive fine particles, a solution or dispersion of a conductive polymer or a dispersion of conductive fine particles may be patterned by an inkjet method. It may be formed by lithography, laser ablation, or the like. In addition, ink containing conductive polymer or conductive fine particles, conductive paste (silver paste, gold paste, carbon paste, etc.) can be patterned by printing methods such as letterpress, intaglio, lithography, screen printing, gravure printing, and inkjet methods. It is also possible to use the method of

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

Further, the surfaces of the source electrode and the drain electrode are coated with aliphatic alkyl thiol compounds 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-nitrothiophenol It may be modified with an aromatic thiol compound such as phenol.

Various insulating materials can be used as the material for the gate insulating layer, and inorganic insulators or organic polymer compounds are preferable.
Inorganic insulators include silicon oxide (SiO ₂ ), silicon nitride, aluminum oxide, aluminum nitride, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, and lead zirconate titanate. , lead lanthanum titanate, strontium titanate, barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, yttrium trioxide, and more. Preferred are silicon oxide, silicon nitride, aluminum oxide, tantalum oxide and titanium oxide.

Examples of methods for forming a 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 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 and wet processes such as various printing methods and inkjet methods, and can be appropriately selected and applied according to the properties of the materials used. When a silicon-based material is used as the gate electrode and the gate insulating layer is formed before forming the organic semiconductor, the thermal oxidation method may be used.

Organic polymer compounds used for the gate insulating layer include polyimide, polyamide, polyester, polyacrylate, photo-radical polymerization photo-curable resins, photo-cationic photo-polymerization photo-curable resins, or copolymers containing an acrylonitrile component. , polyvinylphenol, polyvinylalcohol, polystyrene, novolac resin, polyvinylidene fluoride, cyanoethylpullulan, poly(perfluoroalkenyl vinyl ether), parylene and the like can be used. A wet process is preferable as a method for forming a gate insulating layer using an organic polymer compound.
The insulating material used for the gate insulating layer may be used singly or in combination.

When using, for example, silicon oxide as an inorganic insulator for the gate insulating layer, the surface of the silicon oxide that forms the interface with the organic semiconductor layer is made of, for example, hexamethyldisilazane, octadecyltrimethoxysilane, octyltrichlorosilane, Octadecyltrichlorosilane, benzyltrichlorosilane, 1-hexylphosphonic acid, 1-octylphosphonic acid, 1-hexadecylphosphonic acid, 3,7,11,15-tetramethyl-1-hexadecylphosphonic acid, etc. may have been processed.
In addition, when an organic polymer compound is used for the gate insulating layer and the organic semiconductor layer is formed after forming the gate insulating layer, the gate insulating layer made of the organic polymer compound is subjected to a rubbing treatment before the organic semiconductor layer is formed. may be formed.
Although the film thickness of the gate insulating layer is not particularly limited, it is generally preferably set in the range of several nm to several tens of μm, more preferably 5 nm to 10 μm, still more preferably 10 nm to 5 μm. is.

The organic transistor of the present invention contains at least one compound represented by the general formula (1) in the organic semiconductor layer, and the compound represented by the general formula (1) is You may use and may use multiple types together.

Furthermore, the organic semiconductor layer comprises at least one compound represented by the general formula (1) and other carrier-transporting compounds (e.g., polyacetylene derivatives, polythiophene derivatives, polythienylenevinylene derivatives, polyphenylene derivatives, polyphenylenevinylene derivatives). , polypyrrole derivatives, polyaniline derivatives, polyarylamine derivatives, polyquinoline derivatives, perylene derivatives, tetracene derivatives, pentacene derivatives, phthalocyanine derivatives, etc.). In this case, the content of the compound represented by general formula (1) is preferably 20% by mass or more, more preferably 50% by mass or more.

Furthermore, the organic semiconductor layer may be formed from at least one compound represented by general formula (1) and a polymer compound.
Such polymer compounds include, for example, polyacrylic acid derivatives, polymethacrylic acid derivatives, poly(cyclohexyl methacrylate) derivatives, polyethylene derivatives, polypropylene derivatives, polyisoprene derivatives, polybutadiene derivatives, polyisobutylene derivatives, polymethylpentene derivatives,
Poly(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 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 thereof may be used in combination.
In addition, when at least one compound represented by the general formula (1) and a polymer compound are used in combination to form an organic semiconductor layer, at least one compound represented by the general formula (1) is included. The amount is preferably 5% by mass or more, more preferably 20% by mass or more, relative to the polymer compound.

The organic transistor of the present invention functions as a p-type (holes function as carriers) organic transistor or an n-type (electrons function as carriers) organic transistor, preferably as a p-type organic transistor. preferably used.

A method for forming the organic semiconductor layer is not particularly limited, and a known forming method can be used.
Formation methods include, for example, 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, a plasma polymerization method, a thermal transfer method, a laser transfer method, and the like. 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-Blodgett method), various printing methods, inkjet method Wet processes such as

When forming the organic semiconductor layer 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 such solvents include water, methanol, ethanol, isopropyl alcohol, butanol, hexanol, methyl cellosolve, ethyl cellosolve, ethylene glycol, 1,2-propanediol, 1,3-propanediol, octafluoropentanol, pentafluoro Alcohol solvents such as propanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, acetophenone, and propiophenone, ester solvents such as ethyl acetate, butyl acetate, and γ-butyrolactone, diethyl ether, Ether solvents such as dibutyl ether, dioxane, tetrahydrofuran, cyclopentyl methyl 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, indane, phenylcyclohexane, decahydronaphthalene, trimethylcyclohexane, bicyclohexyl, dichloromethane, chloroform, dichloroethane, tetrachloroethane, tetrachloroethylene, chlorobenzene, fluorofluoro Halogenated hydrocarbon solvents such as benzene, dichlorobenzene, trichlorobenzene, 1-fluoronaphthalene and 1-chloronaphthalene; nitrile solvents such as acetonitrile, propionitrile, methoxyacetonitrile, glutarodinitrile and benzonitrile; aprotic polar solvents such as oxide, sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, tetramethylurea; organic solvent. One of these solvents may be used alone, or two or more of them may be used in combination.
The concentration of at least one compound represented by general formula (1) in such a solvent is not particularly limited, but is generally from 0.01 to 20% by mass, more preferably from 0.05 to It is preferable to prepare to about 15% by mass.

Although the film thickness of the organic semiconductor layer is not particularly limited, it is generally preferably set in the range of several nm to several tens of μm, more preferably 1 nm to 10 μm, and still more preferably 5 nm to 10 μm. 1 μm.

In the present invention, after formation of the organic semiconductor layer, post-treatment may be performed as desired.
For example, after the formation of the organic semiconductor layer, it may be possible to apply a heat treatment to relax the distortion of the film thickness that occurred during the formation, or to improve the pinholes that were generated.
Further, in some cases, it is 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 temperature is about room temperature to 200.degree. C., preferably 40.degree. C. to 150.degree. The heat treatment may be performed in the air or under an atmosphere of an inert gas such as nitrogen or argon.

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

As the donor dopant, any compound having a function of donating electrons to the organic compound of the organic semiconductor layer can be suitably used.
Examples of donor dopants 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, Rare earth metals such as Tb, Dy, Ho, Er and Yb, ammonium ions, R ₄ P ⁺ (R represents an alkyl group), R ₄ As ⁺ (R represents an alkyl group), R ₃ S ⁺ (R represents an represents an alkyl group), acetylcholine, and the like.

As the acceptor dopant, any compound having a function of removing electrons from the organic compound of the organic semiconductor layer can be suitably used.
Examples of acceptor dopants include halogen compounds such as Cl ₂ , Br ₂ , I ₂ , ICl, ICl ₃ , IBr and IF, PF ₅ , AsF ₅ , SbF ₅ , BF ₃ , BCl ₃ ,
Lewis acids such as _BBr3 , _SO3 , HF, HCl, _{HNO3 , H2SO4} , _HClO4 ,
_Protic acids such as FSO3H _{, ClSO3H ,} CF3SO3H, organic acids such as acetic acid, formic acid, amino acids, FeCl3, _FeOCl , _TiCl4 , _ZrCl4 , _HfCl4 , _NbF5 , _NbCl5 , _TaCl5 , MoCl ₅ , WF ₅ , WCl ₆ , UF ₆ , transition metal compounds such as LnCl ₃ (Ln=La, Ce, Nd, Pr and other lanthanides and Y), Cl ⁻ , Br ⁻ , I ⁻ , ClO ₄ ⁻ , Electrolyte anions such as PF ₆ ⁻ , AsF ₅ ⁻ , SbF ₆ ⁻ , BF ₄ ⁻ , and sulfonate anions are included.
As a doping method, a method of introducing the dopant after forming the organic semiconductor layer or a method of introducing the dopant during the formation of the organic semiconductor layer can be applied.

In addition, the organic transistor of the present invention may be provided with a gas barrier layer on the entire or part of the outer peripheral surface of the organic transistor for the purpose of reducing the influence of oxygen, moisture, etc. in the atmosphere. Materials for forming the gas barrier layer include, for example, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, and poly(perfluoroalkenyl vinyl ether). Furthermore, the inorganic insulators mentioned as the materials 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 liquid crystal display elements, organic electroluminescence elements, electronic paper, various sensors, RFIDs (radio frequency identification cards), and the like.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
(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 becomes the gate electrode, and the SiO ₂ layer formed on the surface of the silicon substrate becomes the gate insulating layer. On this, under vacuum (5×10 ⁻⁴ Pa), the compound of Exemplified Compound No. 6 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. Furthermore, using a mask, gold was vapor-deposited thereon to form a source electrode and a drain electrode. The thickness of the source electrode and 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 characteristics as a p-type transistor element.
The charge mobility was obtained from the saturation region of the current-voltage (IV) characteristics of the organic transistor.
Further, the drain current value was measured when the drain bias was set to -50 V and the gate bias was set to -50 V and 0 V to obtain the on/off ratio of the current.
Furthermore, the fabricated element was subjected to a wet heat test (after storage for 24 hours in an atmosphere of 60° C. and a relative humidity of 80%), and the charge mobility and current on/off ratio were measured in the same manner. The measurement results are shown in Table 1.

(Examples 2-7)
In Example 1, when forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 6, the compound of Exemplified Compound No. 14 (Example 2), the compound of Exemplified Compound No. 15 (Example 3), the exemplary compound Compound No. 25 (Example 4), Compound No. 26 (Example 5), Compound No. 34 (Example 6), Compound No. 38 (Example 7) , an organic transistor was fabricated by the method described in Example 1.
In addition, the produced organic transistor showed the characteristic as a p-type transistor element.
Furthermore, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after preparation and after the wet heat test (after storage for 24 hours in an atmosphere of 60 ° C. and a relative humidity of 80%). It was shown to.

The compounds used in the formation of the organic semiconductor layer in the following comparative examples are the compounds represented by the following formulas (A) to (L).

(Comparative Examples 1 to 3)
In Example 1, when forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 6, the compound of formula (E) (Comparative Example 1), the compound of formula (F) (Comparative Example 2), the formula ( An organic transistor was produced by the method described in Example 1, except that the compound of J) (Comparative Example 3) was used.
In addition, the produced organic transistor showed the characteristic as a p-type transistor element.
Furthermore, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after preparation and after the wet heat test (after storage for 24 hours at 60 ° C. and an atmosphere of 80% relative humidity), 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 a high charge mobility, a large current on/off ratio, and excellent storage stability (moisture and heat resistance). It is clear that

(Example 8)
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 becomes the gate electrode, and the SiO ₂ layer formed on the surface of the silicon substrate becomes the gate insulating layer. A silicon substrate was heated to 80° C., and a chlorobenzene solution (concentration: 0.3% by mass) of Exemplified Compound No. 2 was applied thereon. An organic semiconductor layer consisting of compound No. 2 was formed. Furthermore, using a mask, gold was vapor-deposited thereon to form a source electrode and a drain electrode. The thickness of the source electrode and drain electrode was 40 nm, the channel width was 5 mm, and the channel length was 70 μm.
In addition, the produced organic transistor showed the characteristic as a p-type transistor element.
Furthermore, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after preparation and after the wet heat test (after storage for 24 hours at 60 ° C. and an atmosphere of 80% relative humidity), and the results are shown in Table 2. It was shown to.

(Examples 9-13)
In Example 8, in forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 2, the compound of Exemplified Compound No. 8 (Example 9), the compound of Exemplified Compound No. 13 (Example 10), the exemplary compound Organic transistor by the method described in Example 8 except that the compound No. 27 (Example 11), the compound No. 33 (Example 12), and the compound No. 37 (Example 13) were used. was made.
In addition, the produced organic transistor showed the characteristic as a p-type transistor element.
Furthermore, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after preparation and after the wet heat test (after storage for 24 hours at 60 ° C. and an atmosphere of 80% relative humidity), and the results are shown in Table 2. It was shown to.

(Comparative Examples 4 to 10)
In Example 8, when forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 2, the compound of formula (A) (Comparative Example 4), the compound of formula (B) (Comparative Example 5), the formula ( H) (Comparative Example 6), Compound of Formula (I) (Comparative Example 7), Compound of Formula (J) (Comparative Example 8), Compound of Formula (K) (Comparative Example 9), Formula (L) An organic transistor was produced by the method described in Example 8 except that the compound of (Comparative Example 10) was used.
In addition, the produced organic transistor showed the characteristic as a p-type transistor element.
Furthermore, by the method described in Example 1, the characteristics of the organic transistor were examined immediately after preparation and after the wet heat test (after storage for 24 hours at 60 ° C. and an atmosphere of 80% relative humidity), 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, large current on/off ratio, and excellent storage stability (moisture and heat resistance). It is clear that

(Example 14)
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 becomes the gate electrode, and the SiO ₂ layer formed on the surface of the silicon substrate becomes the gate insulating layer.
A coating solution was prepared by dissolving 10 mg of Exemplified Compound No. 10 and 10 mg of polystyrene (manufactured by Sigma-Aldrich, Mw: 350000) in 2 g of 1,2-dichlorobenzene.
A silicon substrate was heated to 80° C., this coating solution was applied thereon, and 1,2-dichlorobenzene was evaporated to form a 50 nm-thick organic semiconductor composed of the compound of Exemplified Compound No. 10 and polystyrene. formed a layer.
Furthermore, using a mask, gold was vapor-deposited thereon to form a source electrode and a drain electrode. The thickness of the source electrode and drain electrode was 40 nm, the channel width was 5 mm, and the channel length was 70 μm.
In addition, the produced organic transistor showed the characteristic 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 15-18)
In Example 14, when forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 10, the compound of Exemplified Compound No. 13 (Example 15), the compound of Exemplified Compound No. 19 (Example 16), the exemplary compound An organic transistor was produced by the method described in Example 14, except that the compound No. 27 (Example 17) and the compound No. 40 (Example 18) were used.
In addition, the produced organic transistor showed the characteristic 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 11 to 15)
In Example 14, in forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 10, the compound of formula (C) (Comparative Example 11), the compound of formula (D) (Comparative Example 12), the formula ( F) (Comparative Example 13), the compound of formula (G) (Comparative Example 14), and the compound of formula (K) (Comparative Example 15) were used, but using the method described in Example 14. was made.
In addition, the produced organic transistor showed the characteristic 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 using the compound represented by the general formula (1) and the polymer compound together for the organic semiconductor layer has a high charge mobility and a large current on/off ratio. It is clear that In addition, the organic transistors of the above Examples also exhibited excellent storage stability in the moist heat test.

INDUSTRIAL APPLICABILITY The organic transistor of the present invention has high charge mobility, large current on/off ratio, and excellent storage stability (moisture and heat resistance). , 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, one of X ₁ and X ₄ is a group represented by the following formula (a), the other is a hydrogen atom or an aryl group, and X ₂ and X ₃ represent hydrogen. Alternatively, _{one of} X2 and X3 is a group represented by the following formula (a), the other is a hydrogen atom or an aryl group, and X1 _and X4 _represent hydrogen .

(In formula (a), n represents an integer of 2 to 10, and R represents a cyclic alkyl group)]

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