JP5436875B2 - Organic transistor - Google Patents

Description

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

  Conventionally, a thin film transistor (TFT) made of amorphous silicon or polycrystalline silicon has been widely used as a switching element for flat panel display such as a liquid crystal display device. However, a CVD apparatus used for manufacturing a thin film transistor using silicon is expensive, and manufacturing a large-sized thin film transistor element has a drawback of increasing manufacturing cost.

  In addition, since amorphous silicon and polycrystalline silicon are formed at a high temperature, there is a problem that a plastic material that is lightweight and flexible but has poor heat resistance cannot be used as a substrate. .

  In order to solve the above problem, an organic transistor (also referred to as an organic thin film transistor or an organic TFT) using an organic compound for a channel semiconductor layer (hereinafter referred to as an organic semiconductor layer) instead of amorphous silicon or polycrystalline silicon is proposed. (Non-Patent Document 1).

  As a method for forming the organic semiconductor layer, for example, a vacuum deposition method or a coating method is known. According to these film formation methods, it is easy to increase the size of the organic transistor element while suppressing the manufacturing cost. .

  Furthermore, the temperature required for film formation can be lowered, and organic transistors using organic compounds can use plastic materials for the substrate, which can be applied to flexible display elements. Expectations are gathered for the transformation.

  A practical organic transistor needs to have characteristics such as high charge mobility and a large current on / off ratio. Here, the term “on / off ratio” means the ratio of the current between the source electrode and the drain electrode when the organic transistor is on to the current between the source electrode and the drain electrode when the organic transistor is off. To do.

  Furthermore, excellent storage stability is required for practical application of organic transistors.

  To date, organic transistors using, for example, pentacene as the organic semiconductor layer have been proposed (Non-Patent Document 2).

  However, an organic transistor using pentacene has a problem that it has a low function as an organic transistor in the atmosphere and low storage stability.

  Furthermore, an organic transistor using a thiophene oligomer (α-hexathienylene) as an organic semiconductor layer has been proposed (Non-patent Document 3). However, the organic transistor also has a drawback that its storage stability in air is low.

  Further, it is described that 2,7-diphenyl [1] benzothieno [3,2-b] [1] benzothiophene is useful for an organic semiconductor layer of an organic transistor (Non-patent Document 4). However, an organic transistor using 2,7-diphenyl [1] benzothieno [3,2-b] [1] benzothiophene in the organic semiconductor layer cannot be said to have sufficiently high charge mobility. There was found.

  In addition, an organic transistor in which an organic semiconductor layer is formed by a wet process using an organic solvent using 2,7-dialkyl [1] benzothieno [3,2-b] [1] benzothiophene, regardless of vapor deposition. It has been proposed (Non-Patent Document 5).

  2,7-dialkyl [1] benzothieno [3,2-b] [1] benzothiophene has a relatively high solubility in an organic solvent, and an organic semiconductor layer can be formed by a wet process. In order to improve the temperature, a step of annealing at a relatively high temperature (80 ° C.) after coating and drying is required.

  As a result of studies by the present inventors, when an annealing step is not performed, the mobility of an organic transistor using 2,7-dialkyl [1] benzothieno [3,2-b] [1] benzothiophene for the organic semiconductor layer is studied. Turned out not to be very expensive.

  At present, development of further improved organic transistors is required for practical use.

Appl. Phys. Lett. 63, 1372 (1993) Appl. Phys. Lett. , 72, 1854 (1998) Science, 268, 270 (1995) J. et al. Amer. Chem. Soc. , 128, 12604 (2006) J. et al. Amer. Chem. Soc. , 129, 15732 (2007)

  To date, organic transistors using various organic compounds as organic semiconductor layers have been proposed, but none of them has practically satisfactory characteristics. .

  In view of the above, the present invention is to provide an organic transistor having high charge mobility, a large current on / off ratio, and excellent storage stability.

  As a result of intensive studies to solve the above problems, the inventor of the present invention has an organic transistor containing a compound represented by the general formula (1) in an organic semiconductor layer, which has a high charge mobility and a large current on / It has been found that it has an off-ratio and is excellent in storage stability, and has completed the present invention.

That is, the present invention
An organic transistor having an organic semiconductor layer is an organic transistor comprising at least one compound represented by the general formula (1) in the organic semiconductor layer.
A ₁ -YA ₂ (1)
{In Formula (1), A ₁ and A ₂ are each independently a group represented by Formula (a)

[In Formula (a), X _{1 to} X ₇ are each independently a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxy group, or substituted or unsubstituted aryl. Y ₁ and Y ₂ each independently represent a sulfur atom, or N—R (where R is a hydrogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxyalkyl group, or a substituted group). Or represents an unsubstituted aryl group)
Y represents —CX ₈ ═CX ₉ — (X ₈ and X ₉ each independently represents a hydrogen atom, a halogen atom or a cyano group), or —C≡C—}

  According to the present invention, it is possible to provide an organic transistor having a high charge mobility, a large current on / off ratio, and excellent storage stability.

It is typical sectional drawing of the organic transistor of this invention. It is typical sectional drawing of the organic transistor of this invention. It is typical sectional drawing of the organic transistor of this invention. It is typical sectional drawing of the organic transistor of this invention.

Hereinafter, the present invention will be described in detail.
The organic transistor of the present invention comprises an organic semiconductor layer containing at least one compound represented by the general formula (1).
A ₁ -YA ₂ (1)
{In Formula (1), A ₁ and A ₂ are each independently a group represented by Formula (a)

[In Formula (a), X _{1 to} X ₇ are each independently a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxy group, or substituted or unsubstituted aryl. Y ₁ and Y ₂ each independently represent a sulfur atom, or N—R (where R is a hydrogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxyalkyl group, or a substituted group). Or represents an unsubstituted aryl group)
Y represents —CX ₈ ═CX ₉ — (X ₈ and X ₉ each independently represents a hydrogen atom, a halogen atom or a cyano group), or —C≡C—}

In the compound represented by the general formula (1), A ₁ and A ₂ are each independently a group represented by the formula (a), and in the group represented by the formula (a), X _{1 to} X ₇ are Each independently represents a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxy group, or a substituted or unsubstituted aryl group.

  In the present specification, the aryl group represents a carbocyclic aromatic group such as a phenyl group or a naphthyl group, for example, a heterocyclic aromatic group such as a furyl group, a thienyl group or a pyridyl group. In addition, the substituent of the aryl group includes a halogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a linear, branched or cyclic alkoxy group having 1 to 20 carbon atoms, or a carbon number of 4 to The aryl group which may be substituted by 20 said halogen atoms, an alkyl group, and an alkoxy group etc. are mentioned.

In the group represented by the formula (a), X _{1 to} X ₇ are more preferably a hydrogen atom, a halogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and a straight chain having 1 to 20 carbon atoms. It represents a chain, branched or cyclic alkoxy group, or a substituted or unsubstituted aryl group having 4 to 20 carbon atoms.

Specific examples of X _{1 to} X _{7 in} the group represented by the formula (a) include, for example, a hydrogen atom; a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; for example, a methyl group, an ethyl group, n -Propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, 1-methylpentyl Group, 4-methyl-2-pentyl group, 3,3-dimethylbutyl group, 2-ethylbutyl group, n-heptyl group, 1-methylhexyl group, cyclohexylmethyl group, n-octyl group, tert-octyl group, 1 -Methylheptyl group, 2-ethylhexyl group, 2-propylpentyl group, n-nonyl group, 2,2-dimethylheptyl group, 2,6-dimethyl -4-heptyl group, 3,5,5-trimethylhexyl group, n-decyl group, n-undecyl group, 1-methyldecyl group, n-dodecyl group, n-tridecyl group, 1-hexylheptyl group, n-tetradecyl group Group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-eicosyl group, cyclopentyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-tert-butylcyclohexyl group, cycloheptyl group A linear, branched or cyclic alkyl group such as a cyclooctyl group;

For example, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, n-pentyloxy group, neopentyloxy group, cyclopentyloxy group, n-hexyloxy group 3,3-dimethylbutyloxy group, 2-ethylbutyloxy group, cyclohexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group, n-nonyloxy group, n-decyloxy group, n -Undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyloxy group, n-heptadecyloxy group, n-octadecyl group Linear, branched or cyclic alkoxy groups such as oxy group and n-eicosyloxy group

For example, phenyl group, 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-n-propylphenyl group, 4-isopropylphenyl group, 4-n-butylphenyl group 4-isobutylphenyl group, 4-tert-butylphenyl group, 4-isopentylphenyl group, 4-tert-pentylphenyl group, 4-n-hexylphenyl group, 4-cyclohexylphenyl group, 4-n-heptylphenyl Group, 4-n-octylphenyl group, 4-n-nonylphenyl group, 4-n-decylphenyl group, 4-n-undecylphenyl group, 4-n-dodecylphenyl group, 4-n-tetradecylphenyl group Group, 2,3-dimethylphenyl group, 2,4-dimethylphenyl group, 2,5-dimethylphenyl group, 2,6-dimethyl group Enyl 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, 4-n-butoxy Phenyl group, 4-isobutoxyphenyl group, 4-n-pentyloxyphenyl group, 4-n-hexyloxyphenyl group, 4-cyclohexyloxyphenyl group, 4-n-heptyloxyphenyl group, 4-n-octyloxy Phenyl 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-triphenyl Fluoromethylphenyl 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′-methoxy) Phenyl) 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, 2-thienyl group, 5-n-propyl-2-thienyl group, 5-n-butyl-2-thienyl group, 5- n-hexyl-2-thienyl group, 5-n-octyl-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, 4-pyridyl group, etc. A substituted aryl group can be mentioned.

In the group represented by the formula (a), Y ₁ and Y ₂ are each independently a sulfur atom, or N—R (where R is a hydrogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic group). Represents an alkoxyalkyl group or a substituted or unsubstituted aryl group, and more preferably a sulfur atom.

When Y ₁ and Y ₂ both represent N—R, the Rs may be the same group or different.

  In N—R in the group represented by the formula (a), R is a hydrogen atom, a linear, branched or cyclic alkyl group, a linear, branched or cyclic alkoxyalkyl group, or a substituted or unsubstituted aryl group. R is preferably a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a linear, branched or cyclic alkoxyalkyl group having 2 to 20 carbon atoms, or 4 to 20 carbon atoms. A substituted or unsubstituted aryl group, more preferably a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a linear, branched or cyclic alkoxyalkyl group having 2 to 20 carbon atoms, or carbon The substituted or unsubstituted aryl group of number 4-20 is represented.

Specific examples of the linear, branched or cyclic alkyl group of R or the substituted or unsubstituted aryl group include, for example, a linear, branched or cyclic alkyl having 1 to 20 carbon atoms exemplified by X _{1 to} X _7. Examples thereof include a group, or a substituted or unsubstituted aryl group having 4 to 20 carbon atoms.

  Specific examples of the linear, branched or cyclic alkoxyalkyl group of R include, for example, a methoxymethyl group, an ethoxymethyl group, an n-butoxymethyl group, an n-hexyloxymethyl group, and a (2-ethylbutyloxy) methyl group. N-octyloxymethyl group, n-decyloxymethyl group, 2-methoxyethyl group, 2-ethoxyethyl group, 2-n-propoxyethyl group, 2-isopropoxyethyl group, 2-n-butoxyethyl group, 2-n-pentyloxyethyl group, 2-n-hexyloxyethyl group, 2- (2′-ethylbutyloxy) ethyl group, 2-n-heptyloxyethyl group, 2-n-octyloxyethyl group, 2 -(2'-ethylhexyloxy) ethyl group, 2-n-decyloxyethyl group, 2-n-dodecyloxyethyl group, 2-n-tetradec Ruoxyethyl group, 2-cyclohexyloxyethyl group, 2-methoxypropyl group, 3-methoxypropyl group, 3-ethoxypropyl group, 3-n-propoxypropyl group, 3-isopropoxypropyl group, 3-n-butoxypropyl group 3-n-pentyloxypropyl group, 3-n-hexyloxypropyl group, 3- (2′-ethylbutoxy) propyl group, 3-n-octyloxypropyl group, 3- (2′-ethylhexyloxy) propyl Group, 3-n-decyloxypropyl group, 3-n-dodecyloxypropyl group, 3-n-tetradecyloxypropyl group, 3-cyclohexyloxypropyl group, 4-methoxybutyl group, 4-ethoxybutyl group, 4 -N-propoxybutyl group, 4-isopropoxybutyl group, 4-n-butoxybutyl group 4-n-hexyloxybutyl group, 4-n-octyloxybutyl group, 4-n-decyloxybutyl group, 4-n-dodecyloxybutyl group, 5-methoxypentyl group, 5-ethoxypentyl group, 5- n-propoxypentyl group, 5-n-pentyloxypentyl group, 6-methoxyhexyl group, 6-ethoxyhexyl group, 6-isopropoxyhexyl group, 6-n-butoxyhexyl group, 6-n-hexyloxyhexyl group 6-n-decyloxyhexyl group, 4-methoxycyclohexyl group, 7-methoxyheptyl group, 7-ethoxyheptyl group, 7-isopropoxyheptyl group, 8-methoxyoctyl group, 8-ethoxyoctyl group, 9-methoxy Nonyl group, 9-ethoxynonyl group, 10-methoxydecyl group, 10-ethoxydecyl group, 10-n -Butoxydecyl group, 11-methoxyundecyl group, 11-ethoxyundecyl group, 12-methoxydodecyl group, 12-ethoxydodecyl group, 12-isopropoxidedecyl group, 14-methoxytetradecyl group, tetrahydrofurfuryl group, etc. And a linear, branched or cyclic alkoxyalkyl group.

In the general formula (1), more preferably, _{A 1} and _{A 2} is a group represented by the formula (a-1) ~ formula (a-4).

［式中、Ｘ_１〜Ｘ_７、およびＲは一般式（１）と同じ意味を表す］

[Wherein, X _{1 to} X ₇ and R represent the same meaning as in the general formula (1)]

In the compound represented by the general formula (1), more preferably, A ₁ and A ₂ are groups represented by the formula (a-1).

In the compound represented by the general formula (1), X ₈ and X ₉ in —CX ₈ ═CX ₉ — represented by Y each independently represent a hydrogen atom, a halogen atom or a cyano group, A hydrogen atom, a fluorine atom, a chlorine atom, or a cyano group, more preferably a hydrogen atom or a fluorine atom, and still more preferably a hydrogen atom.

Further, -CX 8 = _CX 9 _- in its configuration may be trans form in cis form, may be a mixture of cis- and trans-isomer, preferably a trans form.

  The organic transistor of the present invention is characterized in that the organic semiconductor layer contains at least one compound represented by the general formula (1), which has a high charge mobility, which is unconventional, It is possible to provide an organic transistor having a large on / off ratio and excellent storage stability.

  Specific examples of the compound represented by the general formula (1) according to the present invention include the following compounds, but the present invention is not limited thereto.

  The compound represented by the general formula (1) according to the present invention can be produced with reference to a method known per se.

In the general formula (1), the compound in which Y is represented by —CX ₈ ═CX ₉ — includes, for example, a compound represented by the general formula (2), a base (for example, n-BuLi, sodium hydride) and It can manufacture by making the phosphonate ylide prepared from the compound represented by General formula (3) act.

  Further, by reacting a compound represented by the general formula (4) with a phosphonate ylide prepared from a compound represented by the general formula (5) and a base (for example, n-BuLi, sodium hydride). Can be manufactured.

[Wherein A ₁ , A ₂ , X ₈ and X ₉ represent the same meaning as in the general formula (1), and R represents an alkyl group]

  In the compounds represented by general formula (3) and general formula (5), the alkyl group represented by R preferably represents an alkyl group having 1 to 4 carbon atoms.

  In the general formula (1), the compound in which Y is represented by —C≡C— is, for example, a compound represented by the general formula (6) and a palladium catalyst [for example, bis (triphenylphosphine) palladium dichloride]. In the presence of copper iodide and a base, the compound represented by the general formula (7) can be allowed to act.

  In addition, a compound represented by the general formula (9) is added to the compound represented by the general formula (8) in the presence of a palladium catalyst [for example, bis (triphenylphosphine) palladium dichloride], copper iodide and a base. It can be produced by acting [for example, Chem. Rev. 107, 874 (2007) can be referred to].

A ₁ -Z (6)
HC≡C-A ₂ (7)
A ₁ -C≡CH (8)
Z-A ₂ (9)
[Wherein, A ₁ and A ₂ represent the same meaning as in the general formula (1), and Z represents a halogen atom]

  In the compounds represented by general formula (6) and general formula (9), the halogen atom represented by Z is preferably a chlorine atom, a bromine atom, or an iodine atom.

  The compound represented by the general formula (1) according to the present invention may be produced in a form that forms a solvate with a solvent used in some cases (for example, an aromatic hydrocarbon solvent such as toluene). In the organic transistor of the present invention, not only a 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 combination of these methods increases the purity. It is preferred to use

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

  The form of the organic transistor of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an 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 formed on the gate electrode at predetermined intervals. 41 is formed, and an organic semiconductor layer 51 is further stacked 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. Further, a source electrode 62 and a drain electrode 42 are formed at a predetermined interval thereon (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 a predetermined interval, 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 on the substrate 14 at a predetermined interval. 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 a channel region, and the current flowing between the source electrode and the drain electrode is controlled by the voltage applied to the gate electrode, thereby turning on / off. Operate.

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

  Examples of the plastic substrate include polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, triacetylcellulose, and cellulose acetate propionate. A substrate is mentioned.

  Note that when a conductive substrate, for example, silicon is used for 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 material can be used as long as it is a conductive material.

  As electrode materials, for example, indium tin oxide alloy (ITO), tin oxide (NESA), indium zinc oxide (IZO), molybdenum oxide, gold, silver, platinum, copper, indium, aluminum, magnesium, nickel, chromium, 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 alloy, aluminum / lithium alloy, aluminum / scandium / lithium alloy, sodium / potassium alloy and other metals and alloys, fluorine-doped zinc oxide, silicon with improved conductivity Examples thereof include silicon-based materials such as single crystal, polycrystalline silicon, and amorphous silicon, and carbon materials such as carbon black, graphite, and glassy carbon. More preferably, indium tin oxide alloy, gold, silver, platinum, copper, Indium, aluminum, silicon materials with improved conductivity, and carbon materials. These can be used in various forms such as bulk, flakes, and fine particles.

  In addition, as an electrode material, a conductive polymer whose conductivity has been improved by doping treatment (eg, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyethylenedioxythiophene (PEDOT) and polystyrene sulfonic acid complex, etc.) Are also preferably used.

  In addition, these electrode materials may be used individually by 1 type, or may be used together.

  Among the electrode materials listed above, the source electrode and the drain electrode are preferably those having a small electric resistance at the contact surface with the organic semiconductor layer.

  A method for forming each electrode is not particularly limited. For example, a conductive material can be formed using a method such as vapor deposition or sputtering, and patterned into a desired shape by lithograph or etching treatment. it can.

  In addition, when an electrode is formed using a conductive polymer or conductive fine particles, a conductive polymer solution or dispersion, or a conductive fine particle dispersion may be patterned by an ink jet method. It may be formed by lithography or laser ablation. Furthermore, a method of patterning an ink containing a conductive polymer or conductive fine particles, a conductive paste (silver paste, carbon paste, etc.) by a printing method such as relief printing, intaglio printing, planographic printing, and screen printing can also be used.

  The film thickness of the source electrode and the drain electrode is not particularly limited, but in general, it is 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 interval (channel length) is generally preferably set in the range of several hundred nm to several mm, more preferably 100 nm to It is 1 mm, More preferably, it is 1 micrometer-500 micrometers.

  As a material used for the gate insulating layer, various insulating materials can be used, and an inorganic insulator or an organic polymer compound is preferable.

As the inorganic insulator, silicon oxide (SiO ₂ ), silicon nitride, aluminum oxide, aluminum nitride, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate , Lead lanthanum titanate, strontium titanate, barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, trioxide yttrium, and more Preferred are silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, and titanium oxide.

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

  Examples of the organic polymer compound used for the gate insulating layer include polyimide, polyamide, polyester, polyacrylate, a photo-radical polymerization photo-curing resin, a photo-cation polymerization photo-curing resin, or a copolymer containing an acrylonitrile component. Polyvinylphenol, polyvinyl alcohol, polystyrene, novolac resin, polyvinylidene fluoride, cyanoethyl pullulan, and the like can be used. As a method for forming a gate insulating layer using an organic polymer compound, a wet process is preferable.

  The insulating material used for the gate insulating layer may be used alone or in combination.

  In addition, when using, for example, silicon oxide as an inorganic insulator for the gate insulating layer, the surface of silicon oxide serving as an interface with the organic semiconductor layer is, 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. It may be 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 organic semiconductor layer is subjected to a rubbing treatment on the gate insulating layer made of the organic polymer compound. May be formed.

  The thickness of the gate insulating layer is not particularly limited, but in general, it is preferably set in the range of several nm to several tens of μm, more preferably 5 nm to 10 μm, and still more preferably 10 nm to 5 μm. It is.

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

  Further, the organic semiconductor layer includes a compound represented by the general formula (1) and other compounds (for example, polyacetylene derivatives, polythiophene derivatives, polythienylene vinylene derivatives, polyphenylene derivatives, polyphenylene vinylene derivatives, polypyrrole derivatives, polyaniline derivatives, A polyquinoline derivative, a perylene derivative, a tetracene derivative, a pentacene derivative, a phthalocyanine derivative, or the like). In this case, the content of the compound represented by the general formula (1) is preferably 20% by mass or more, and more preferably 50% by mass or more.

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

  The method for forming the organic semiconductor layer is not particularly limited, and a known formation method can be used.

  Examples of the formation method include vacuum deposition, molecular beam epitaxial growth, ion cluster beam, low energy ion beam, ion plating, CVD, sputtering, plasma polymerization, thermal transfer, and laser transfer. Dry process, spray coat method, spin coat method, blade coat method, dip coat method, cast method, roll coat method, bar coat method, die coat method, LB method (Langmuir / Blodget method), various printing methods, ink jet method, etc. Can be mentioned.

  When the organic semiconductor layer is formed by a wet process, a solution in which the compound represented by the general formula (1) is dissolved or dispersed in a solvent is used.

  Examples of such solvents include alcohol solvents such as water, methanol, ethanol, isopropyl alcohol, and butanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; Ether solvents such as ether, dioxane, tetrahydrofuran, anisole, hydrocarbon solvents such as hexane, octane, toluene, xylene, ethylbenzene, cumene, dichloromethane, chloroform, dichloroethane, tetrachloroethane, tetrachloroethylene, chlorobenzene, fluorobenzene, dichlorobenzene, Halogenated hydrocarbon solvents such as trichlorobenzene, acetonitrile, propionitrile, methoxyacetonitrile, gluta Nitrile solvents such as dinitrile and benzonitrile, organic solvents such as aprotic polar solvents such as dimethyl sulfoxide, sulfolane, N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone Can be mentioned. These solvents may be used alone or in combination.

  The concentration of the compound represented by the general formula (1) in the solvent is not particularly limited, but is generally 0.01 to 20% by mass, more preferably about 0.05 to 15% by mass. It is preferable to prepare it.

  Although it does not restrict | limit in particular regarding the film thickness of an organic-semiconductor layer, Generally, it is preferable to set to the range of several nm-dozens of micrometers, More preferably, it is 1 nm-10 micrometers, More preferably, it is 5 nm- 1 μm.

  In the present invention, after the organic semiconductor layer is formed, a post-treatment may be further performed as desired.

  For example, after the organic semiconductor layer is formed, heat treatment may be performed to reduce the distortion of the film thickness generated during the formation or to improve the generated pinholes.

  In addition, it may be preferable to perform heat treatment for the purpose of controlling the arrangement and orientation of molecules in the organic semiconductor layer.

  Although it does not restrict | limit especially regarding the temperature of heat processing, About room temperature-about 200 degreeC, Preferably, it implements at 40 degreeC-150 degreeC. The heat treatment may be performed in the air or in an inert gas atmosphere such as nitrogen or argon.

  In the organic transistor of the present invention, the organic semiconductor layer may be subjected to a doping treatment if desired.

  In addition, as a dopant, both a donor-type dopant and an acceptor-type dopant can be used, and it is preferable to use an acceptor-type dopant.

  As the donor dopant, any compound having a function of donating electrons to the organic compound of the organic semiconductor layer can be preferably used.

Examples of the donor dopant include alkali metals such as Li, Na, K, Rb, and Cs, alkaline earth metals such as Ca, Sr, and Ba, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Rb, Dy, Ho, Er, Yb and other rare earth metals, ammonium ions, R ₄ P ⁺ (R represents an alkyl group), R ₄ As ⁺ (R represents an alkyl group), R ₃ S ⁺ (R represents Represents an alkyl group), and acetylcholine.

  As the acceptor dopant, any compound having a function of removing electrons from the organic compound of the organic semiconductor layer can be preferably used.

Examples of the acceptor dopant include halogen compounds such as Cl ₂ , Br ₂ , I ₂ , ICl, ICl ₃ , IBr ₃ and IF, PF ₅ , AsF ₅ , SbF ₅ , BF ₃ , BCl ₃ , BBr ₃ , SO _3. Lewis acids such as HF, HCl, HNO ₃ , H ₂ SO ₄ , HClO ₄ , FSO ₃ H, ClSO ₃ H, CF ₃ SO ₃ H and other protic acids, acetic acid, formic acid, amino acids and other organic acids, FeCl ₃ , FeOCl, TiCl ₄ , ZrCl ₄ , HfCl ₄ , NbF ₅ , NbCl ₅ , TaCl ₅ , MoCl ₅ , WF ₅ , WCl ₆ , UF ₆ , LnCl ₃ (Ln = La, Ce, Nd, Pr, etc.) ) a transition metal compound, such ^{_{as, Cl -, Br -, I}} -, ClO 4 -, PF 6 -, AsF 5 -, SbF ^-, BF ₄ ^-, etc. electrolyte anions such as sulfonate anions.

  As a doping method, a method of introducing a dopant after forming an organic semiconductor layer, or a method of introducing a dopant at the time of forming the organic semiconductor layer can be applied.

  Moreover, the organic transistor of this invention can also provide a gas barrier layer in the whole or part of the outer peripheral surface of an organic transistor in order to reduce the influence of oxygen, moisture, etc. in the atmosphere. Examples of the material for forming the gas barrier layer include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl chloride, and polyvinylidene chloride. Furthermore, the inorganic insulator mentioned as a material used for a gate insulating layer can also be used for formation of a gas barrier layer.

  In addition, the organic transistor of this invention can be used for a liquid crystal display element, an organic electroluminescent element, electronic paper, various sensors, RFID (radio frequency identification cards) etc., for example.

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

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 top of this, the compound of Exemplified Compound No. 1 was deposited in a thickness of 30 nm under vacuum (5 × 10 ⁻⁴ Pa) at a deposition rate of 0.03 nm / sec to form an organic semiconductor layer. Further, a source electrode and a drain electrode were formed thereon by vapor-depositing gold using a mask. The source electrode and drain electrode had a thickness of 40 nm, a channel width of 5 mm, and a channel length of 20 μm.
The organic transistor manufactured as described above exhibited characteristics as a p-type transistor element. The charge mobility was determined from the saturation region of the current-voltage (IV) characteristics of the organic transistor.
Further, the drain current value was measured when the drain bias was −50 V and the gate bias was −50 V and 0 V, and the current on / off ratio was obtained.
Furthermore, after storing the produced organic transistor element in the atmosphere at 25 ° C. for one month, the charge mobility and the on / off ratio of the current were measured again. The measurement results are shown in Table 1.

(Examples 2 to 11)
In Example 1, instead of using the compound of Exemplified Compound No. 1 in forming the organic semiconductor layer, the compound of Exemplified Compound No. 3 (Example 2), the Compound of Exemplified Compound No. 34 (Example 3), and the Exemplified Compound Compound No. 49 (Example 4), Example Compound No. 69 (Example 5), Example Compound No. 74 (Example 6), Example Compound No. 77 (Example 7), Example Compound No. 81 The compound of Example 8 was used except that the compound of Example Compound No. 91 (Example 9), the compound of Example Compound No. 99 (Example 10) and the compound of Example Compound No. 105 (Example 11) were used. An organic transistor was fabricated by the method described in Example 1.
Further, the characteristics of the organic transistor were examined by the method described in Example 1, and the results are shown in Table 1.

(Comparative Example 1)
In Example 1, an organic transistor was produced by the method described in Example 1 except that pentacene was used instead of using the compound of Exemplary Compound No. 1 when forming the organic semiconductor layer.
Further, the characteristics of the organic transistor were examined by the method described in Example 1, and the results are shown in Table 1.
In addition, the characteristic as an organic transistor was not shown after leaving for one month.

(Comparative Example 2)
In Example 1, an organic transistor was produced by the method described in Example 1 except that α-hexathienylene was used instead of the compound of Example Compound No. 1 in forming the organic semiconductor layer.
Further, the characteristics of the organic transistor were examined by the method described in Example 1, and the results are shown in Table 1.

(Comparative Example 3)
In Example 1, when forming the organic semiconductor layer, instead of using the compound of Example Compound No. 1, 2,7-diphenyl [1] benzothieno [3,2-b] [1] benzothiophene (Non-Patent Document 4) The organic transistor was produced by the method described in Example 1 except that the above was used.
Further, the characteristics of the organic transistor were examined by the method described in Example 1, and the results are shown in Table 1.

(Example 12)
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. When the silicon substrate was heated to 80 ° C. and a chloroform solution (concentration: 0.4 mass%) of the compound of Exemplified Compound No. 5 was applied thereon, the chloroform was evaporated and the Exemplified Compound having a thickness of 80 nm was applied. An organic semiconductor layer made of the compound of No. 5 was formed. Further, a source electrode and a drain electrode were formed thereon by vapor-depositing gold using a mask. The source electrode and drain electrode had a thickness of 80 nm, a channel width of 2 mm, and a channel length of 50 μm.
Furthermore, when the characteristics of the organic transistor were examined by the method described in Example 1, the mobility was 2.2 × 10 ⁻¹ (cm ² / Vsec), and the current on / off ratio was 3.2. × 10 ⁷

(Comparative Example 4)
In Example 12, when forming the organic semiconductor layer, instead of using the compound of Exemplified Compound No. 5, 2,7-dihexyl [1] benzothieno [3,2-b] [1] benzothiophene (Non-patent Document 5) The organic transistor was produced by the method described in Example 12 except that the above was used.
Furthermore, when the characteristics of the organic transistor were examined by the method described in Example 1, the mobility was 8.2 × 10 ⁻² (cm ² / Vsec), and the current on / off ratio was 2.2. × 10 ⁷

  From Table 1, the organic transistor of the present invention has a high charge mobility, a large current on / off ratio, has excellent characteristics as an organic transistor, and further has a stable change with time. It is clear that it is an excellent organic transistor.

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

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

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

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

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

Claims (1)

An organic transistor having an organic semiconductor layer, wherein the organic semiconductor layer contains at least one compound represented by the general formula (1).
A ₁ -YA ₂ (1)
{In Formula (1), A ₁ and A ₂ are each independently a group represented by Formula (a)

Wherein _(a), the X 1 to X ₇ are each independently a hydrogen atom, a halogen atom, a straight-chain having 1 to 20 carbon atoms, branched or cyclic alkyl group, straight chain having 1 to 20 carbon atoms, branched or A cyclic alkoxy group, or a substituted or unsubstituted aryl group having 4 to 20 carbon atoms ,
Y ₁ and Y ₂ are each independently a sulfur atom, or N—R (wherein R is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a straight chain having 2 to 20 carbon atoms , branched or Represents a cyclic alkoxyalkyl group or a substituted or unsubstituted aryl group having 4 to 20 carbon atoms ).
Y represents —CX ₈ = CX ₉ — (X ₈ and X ₉ represent a hydrogen atom ), or —C≡C—}

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