JP5677306B2 - Organic thin film transistor - Google Patents

Description

  The present invention relates to an organic thin film transistor. More specifically, the present invention relates to an organic thin film transistor capable of high-speed operation and low-voltage driving because a charge injection layer bonded to a source electrode and a drain electrode contains a compound having a low contact resistance.

  Thin film transistors (TFTs) are widely used as display switching elements for liquid crystal display devices and the like. A cross-sectional structure of a typical TFT is shown in FIG. As shown in FIG. 1, a TFT has a gate electrode, an insulator layer, and an organic semiconductor layer in this order on a substrate, and has a source electrode and a drain electrode formed on the organic semiconductor layer with a predetermined interval. Have. The organic semiconductor layer forms a channel region, and an on / off operation is performed by controlling a current flowing between the source electrode and the drain electrode with a voltage applied to the gate electrode.

  Conventionally, this TFT has been manufactured using amorphous or polycrystalline silicon. However, since a CVD (Chemical Vapor Deposition) apparatus used for manufacturing a TFT using silicon is very expensive, the TFT is used. The increase in the size of the display device, etc., has been accompanied by a significant increase in manufacturing cost. In addition, since the process of forming amorphous or polycrystalline silicon is performed at a very high temperature, the types of materials that can be used as a substrate are limited, and a lightweight resin substrate cannot be used. It was.

In order to solve the above problem, a TFT using an organic substance instead of amorphous or polycrystalline silicon has been proposed. Vacuum deposition and coating methods are known as film formation methods used when forming TFTs with organic materials. However, according to these film formation methods, an increase in the size of the element can be realized while suppressing an increase in manufacturing cost. Therefore, the process temperature required for film formation can be made relatively low. For this reason, a TFT using an organic substance has an advantage that there are few restrictions when selecting a material used for a substrate, and its practical use is expected.
TFTs using organic substances have been actively reported, and examples thereof include Non-Patent Documents 1 to 16.

Organic materials used in the organic compound layer of TFT include p-type polymers such as conjugated polymers and thiophenes (Patent Documents 1 to 5 etc.), metal phthalocyanine compounds (Patent Document 6 etc.), and condensed aromatic hydrocarbons such as pentacene. (Patent Documents 7 and 8, etc.) are used in the form of a simple substance or a mixture with other compounds.
In addition, as for n-type materials, for example, Patent Document 9 discloses 1,4,5,8-naphthalene tetracarboxyl dianhydride (NTCDA) and the like, and Patent Document 10 discloses fluorinated phthalocyanine. Has been.
These organic TFTs have a problem that the contact resistance between the source and drain electrodes and the organic semiconductor is large, and the drive voltage is high. Furthermore, when the contact resistance becomes too large, the field effect mobility is lowered and the ON / OFF ratio is also lowered.

（式中、Ｉ_Ｄ：ドレイン電流，Ｖ_Ｄ：ドレイン電圧，Ｖ_Ｇ：ゲート電圧，Ｖ_ｔｈ：閾値電圧，μ：電界効果移動度，Ｃ：単位面積当たりの絶縁膜容量，Ｌ：チャネル長，Ｗ：チャネル幅である。）In general, in the organic TFT, the following formulas (1) and (2) are used to calculate the field effect mobility. Expression (1) is an expression established in a region called a linear region where the drain voltage is small, and Equation (2) is an equation established in a region called a saturation region where the drain voltage is large.

(Wherein I _D : drain current, V _D : drain voltage, V _G : gate voltage, V _th : threshold voltage, μ: field effect mobility, C: insulating film capacitance per unit area, L: channel length, W: Channel width.)

  In the above equation, in an ideal case where the junction between the organic semiconductor and the source and drain electrodes is an ohmic junction and there is no charge injection barrier, μ is close to the value specific to the substance. However, since there is generally a contact resistance between the organic semiconductor and the metal electrode, the current-voltage relationship deviates from the equation (1) in the region where the drain voltage is small, and the switching characteristics in this region are good. Not. Furthermore, a voltage drop occurs at the metal / organic semiconductor interface, and the effective voltage applied to the organic semiconductor decreases accordingly, so that the field-effect mobility of the equations (1) and (2) is calculated to be small, and the response speed In addition, there are problems such as a decrease in on / off ratio and an increase in drive voltage.

  In order to solve this problem, an intermediate layer (charge injection layer) is generally inserted between the source and drain electrodes and the organic semiconductor. As the material of the intermediate layer, for example, in Patent Document 11, a hole injection material (4,4′-bis [phenyl (3-methylphenyl) amino] biphenyl) (TPD) and electron injection of an organic electroluminescence (EL) element are used. The material 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole) (PBD) is used.

  In Patent Document 12, the source electrode and the drain electrode each include a carrier relay film and a carrier conductive film, and the metal constituting the carrier relay film in contact with the organic semiconductor has a work function in the vicinity of the ionization potential of the organic semiconductor. To disclose. Patent Document 13 discloses an organic thin film transistor in which a charge injection layer made of an inorganic material is inserted between a source electrode and a drain electrode and an organic semiconductor film. In addition, in Patent Document 14, a carbon nanotube is provided between the electrode and the organic semiconductor layer. In Patent Document 15, an intermediate layer made of copper phthalocyanine or the like is formed, and in Patent Document 16, an intermediate layer having a permanent dipole moment such as polyvinylidene fluoride is formed. In Patent Document 17, the intermediate layer is formed using a hexaazatriphenylene-based material.

In Non-Patent Document 17, an attempt is made to improve the charge injection efficiency between the electrode and the organic semiconductor by treating the electrode with pentafluorothiophenol.
A combination of the above techniques is also conceivable. In Patent Document 18, a layer containing an organic compound having a hole transporting property and a metal oxide, and a layer containing an organic compound having an electron transporting property and an alkali metal or alkaline earth metal, respectively. Is inserted between the electrode and the organic semiconductor.
However, when these disclosed materials were used, although the voltage could be slightly lowered, the performance was insufficient practically.

As another voltage reduction technique, in Non-Patent Document 18, a source electrode, an organic semiconductor layer, and a drain electrode are stacked in a vertical direction, and a gate electrode is inserted between the source electrode and the drain electrode. When the vertical transistor structure is used, the same charge transport material as that of the organic EL element can be used (Non-patent Document 18, copper phthalocyanine is used as the charge transport material), so that the contact resistance with the electrode is reduced and charge injection is performed. To lower the voltage.
However, the vertical transistor structure has a problem that if the charge injection from the electrode is improved, the OFF current increases and the ON / OFF ratio decreases.

  Patent Document 19 discloses that a material used for an organic semiconductor layer of an organic thin film transistor is a phenyl group at both ends, and two or more triple bonds and one or more divalent aromatic hydrocarbon groups or aromatics between them. A compound in which group heterocyclic groups are alternately bonded is disclosed. However, there is no disclosure or suggestion of using this compound in the charge injection layer disposed between the organic semiconductor layer and the source electrode and between the organic semiconductor layer and the drain electrode.

  Here, since the organic semiconductor layer has a function of moving charges from the source electrode to the drain electrode, it is required to be made of a material having high mobility. And in the organic thin-film transistor which has a charge injection layer, the grade for which functions other than a mobility are calculated | required by an organic-semiconductor layer is low. In particular, when an organic compound is used for the charge injection layer as in the organic thin film transistor of the present invention, organic substances are brought into contact with each other, so that smooth charge transfer between the interfaces tends to occur. For this reason, the importance of functions other than mobility is further reduced.

  On the other hand, the charge injection layer is required to have a function of injecting charges from the electrodes. The mobility of the charge injection layer is also important, but considering the thickness of the charge injection layer preferably 0.3 nm to 100 nm, which is extremely shorter than the channel length of preferably 5 μm to 100 μm, the organic semiconductor Mobility is less important than what is required for a layer. For example, the mobility of TPD and PBD used for the intermediate layer material in Patent Document 11 and copper phthalocyanine used in Patent Document 15 are not high.

The charge injection layer is required to have a function of reducing contact resistance with an electrode made of an inorganic material such as metal. In addition, the source and drain electrodes repeat oxidation and reduction at the interface with the charge injection layer due to charge transfer. For this reason, the material for the charge injection layer is required to have resistance to oxidation and reduction.
Thus, an excellent material for an organic semiconductor layer cannot be easily transferred to a material for a charge injection layer.

JP-A-8-228034 JP-A-8-228035 Japanese Patent Laid-Open No. 9-232589 Japanese Patent Laid-Open No. 10-125924 Japanese Patent Laid-Open No. 10-190001 JP 2000-174277 A JP-A-5-55568 JP 2001-94107 A Japanese Patent Laid-Open No. 10-135481 JP-A-11-251601 Japanese Patent Laid-Open No. 10-125924 JP 2004-55652 A JP 2005-327797 A JP 2004-356530 A JP 2005-72495 A JP 2005-109028 A JP 2007-520075 A JP 2006-324655 A WO2008 / 044695 pamphlet

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  The present invention has been made in order to solve the above-described problems. An organic thin film transistor that has a high response speed (driving speed), a large on / off ratio, and can be driven at a low voltage, and an organic thin film light emitting device using the organic thin film transistor. An object is to provide a transistor.

As a result of intensive studies to achieve the above object, the present inventors can achieve the above object by using a compound represented by the following general formula (1) in the charge injection layer of the organic thin film transistor. And the present invention has been completed.
That is, in the present invention, at least three terminals of a gate electrode, a source electrode, and a drain electrode, an insulator layer, and an organic semiconductor layer are provided on a substrate, and a source-drain current is controlled by applying a voltage to the gate electrode. In the organic thin film transistor, a charge injection layer is provided between the organic semiconductor layer and the source-drain, and the charge injection layer provides an organic thin film transistor containing a compound represented by the following formula (1).

[In the formula (1), Ar ₁ is represented by the following formula (2), and Ar ₃ is represented by the following formula (3).

(In the formulas (2) and (3), R _{1 to} R ₁₀ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, or 1 carbon atom. -30 alkoxy group, haloalkoxy group having 1-30 carbon atoms, alkthio group having 1-30 carbon atoms, haloalkylthio group having 1-30 carbon atoms, alkylamino group having 1-30 carbon atoms, 2-30 carbon atoms. Dialkylamino group (the alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), an alkylsulfonyl group having 1 to 30 carbon atoms, a haloalkylsulfonyl group having 1 to 30 carbon atoms, or 6 to 6 carbon atoms It is a 60 aromatic hydrocarbon group, a C1-C60 aromatic heterocyclic group, a C3-C30 alkylsilyl group, or a cyano group, and each of these groups may have a substituent.
R _{1 to} R ₅ and R _{6 to} R ₁₀ may be adjacent to each other to form a saturated or unsaturated cyclic structure. )
Ar ₂ is an optionally substituted divalent aromatic hydrocarbon group having 6 to 60 carbon atoms and an optionally substituted divalent aromatic heterocyclic group having 2 to 60 carbon atoms. is there.
n is an integer of 1-20. ]

  In addition, the present invention provides an organic thin film transistor that obtains light emission by using a current flowing between a source and a drain in an organic thin film transistor and controls light emission by applying a voltage to a gate electrode.

  The organic thin film transistor of the present invention has a high response speed (driving speed), a large on / off ratio, a low driving voltage, and has high performance as a transistor, and can emit light. Can also be used.

It is sectional drawing which shows the typical structure of a thin-film transistor. It is a figure which shows one Embodiment of the organic thin-film transistor of this invention. It is a figure which shows other embodiment of the organic thin-film transistor of this invention. It is a figure which shows other embodiment of the organic thin-film transistor of this invention. It is a figure which shows other embodiment of the organic thin-film transistor of this invention. 1 is a diagram illustrating a configuration of an organic thin film transistor of Example 1. FIG. It is a figure which shows the structure of the organic thin-film transistor of Example 14. It is a figure which shows the output curve of the organic thin-film transistor of Example 1. FIG. It is a figure which shows the output curve of the organic thin-film transistor of the comparative example 1.

  The organic thin film transistor of the present invention is provided with at least three terminals of a gate electrode, a source electrode, and a drain electrode, an insulator layer, and an organic semiconductor layer on a substrate, and a source-drain current is controlled by applying a voltage to the gate electrode. In the organic thin film transistor, a charge injection layer is provided between the organic semiconductor layer and the source-drain, and the charge injection layer contains a compound represented by the following general formula (1).

In the general formula (1), Ar ₁ is represented by the following general formula (2), and Ar ₃ is represented by the following general formula (3).

In the general formulas (2) and (3), R _{1 to} R ₁₀ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, or 1 to carbon atoms. 30 alkoxy groups, 1-30 haloalkoxy groups, 1-30 alkylthio groups, 1-30 haloalkylthio groups, 1-30 alkylamino groups, 2-30 carbon atoms Dialkylamino group (the alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), an alkylsulfonyl group having 1 to 30 carbon atoms, a haloalkylsulfonyl group having 1 to 30 carbon atoms, or 6 to 60 carbon atoms. An aromatic hydrocarbon group, an aromatic heterocyclic group having 1 to 60 carbon atoms, an alkylsilyl group having 3 to 30 carbon atoms, or a cyano group, and each of these groups may have a substituent.
R _{1 to} R ₅ and R _{6 to} R ₁₀ may be adjacent to each other to form a saturated or unsaturated cyclic structure.

Hereinafter, specific examples of each group represented by R _{1 to} R ₁₀ will be described.
Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.
Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, n-pentyl group, n-hexyl group, and n-heptyl group. N-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group and the like.
Examples of the haloalkyl group include chloromethyl group, 1-chloroethyl group, 2-chloroethyl group, 2-chloroisobutyl group, 1,2-dichloroethyl group, 1,3-dichloroisopropyl group, 2,3-dichloro- t-butyl group, 1,2,3-trichloropropyl group, bromomethyl group, 1-bromoethyl group, 2-bromoethyl group, 2-bromoisobutyl group, 1,2-dibromoethyl group, 1,3-dibromoisopropyl group, 2,3-dibromo-t-butyl group, 1,2,3-tribromopropyl group, iodomethyl group, 1-iodoethyl group, 2-iodoethyl group, 2-iodoisobutyl group, 1,2-diiodoethyl group, 1, 3-diiodoisopropyl group, 2,3-diiodo-t-butyl group, 1,2,3-triiodopropyl group, fluoromethyl group, -Fluoroethyl group, 2-fluoroethyl group, 2-fluoroisobutyl group, 1,2-difluoroethyl group, difluoromethyl group, trifluoromethyl group, pentafluoroethyl group, perfluoroisopropyl group, perfluorobutyl group, perfluoro A cyclohexyl group etc. are mentioned.
The alkoxy group is a group represented by —OX ¹ , and examples of X ¹ include the same examples as described for the alkyl group, and the haloalkoxy group is represented by —OX ^2. Examples of X ² include the same examples as described for the haloalkyl group.
The alkylthio group is a group represented by —SX ¹ , and examples of X ¹ include the same examples as described for the alkyl group, and the haloalkylthio group is represented by —SX ^2. Examples of X ² include the same examples as described for the haloalkyl group.

The alkylamino group is a group represented by —NHX ¹ , the dialkylamino group is a group represented by —NX ¹ X ³ , and X ¹ and X ³ are the same as those described for the alkyl group, respectively. Similar examples are given. The alkyl group of the dialkylamino group may be bonded to each other to form a ring structure containing a nitrogen atom, and examples of the ring structure include pyrrole, pyrrolidine, piperidine and the like.
The alkylsulfonyl group is a group represented by —SO ₂ X ¹ , and examples of X ¹ include the same examples as described for the alkyl group, and the haloalkylsulfonyl group includes —SO ₂ a group represented by X ^2, examples of X ² are examples similar to those described in the haloalkyl group.
Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a fluorenyl group, a perylenyl group, a tetracenyl group, and a pentacenyl group.
Examples of the aromatic heterocyclic group include a thiophenyl group, a dithienophenyl group, a benzofuranyl group, a benzothiophenyl group, a quinolinyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and a benzothiadiazonyl group. Can be mentioned.
The alkylsilyl group is a group represented by —SiX ¹ X ² X ³ , and examples of X ¹ , X ² and X ³ are the same as those described for the alkyl group.
Examples of the saturated cyclic structure include a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, and a 1,4 dioxane ring.
Examples of the unsaturated cyclic structure include the same examples as those described for the aromatic hydrocarbon group.

In General Formula (1), Ar ₂ is a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms which may have a substituent, and a divalent having 2 to 60 carbon atoms which may have a substituent. An aromatic heterocyclic group.
The divalent aromatic hydrocarbon group having 6 to 60 carbon atoms is preferably an aromatic hydrocarbon group having 6 to 30 carbon atoms, and examples thereof include 2 such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene or pentacene. And divalent residues such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, and pentacene are preferable.
The divalent aromatic heterocyclic group having 2 to 60 carbon atoms is preferably a condensed polycyclic aromatic heterocyclic ring having 6 to 60 carbon atoms (preferably 8 to 60 carbon atoms), and is preferably a condensed polycyclic aromatic ring. The heterocyclic group is preferably a structure containing a benzene ring or a naphthalene ring, and more preferably a structure containing a benzene ring. For example, divalent residues such as pyrrole, pyridine, pyrimidine, imidazole, thiazole, dithienobenzene, benzothiadiazole, quinoline, benzothiophene, benzodithiophene, dibenzothiophene, benzothienobenzothiophene, benzofuran or dibenzofuran can be mentioned. The divalent residues of dithienobenzene, benzothiophene, dibenzothiophene, benzofuran and dibenzofuran are preferred.
Examples of the substituent for Ar ₂ include an alkyl group having 1 to 30 carbon atoms and a haloalkyl group having 1 to 30 carbon atoms. Specific examples of the group include groups described for the alkyl group or haloalkyl group represented by R _{1 to} R ₁₀ .
In the general formula (1), n is an integer of 1 to 20, and may be 1 or a plurality of 2 or more, but is preferably an integer of 1 to 5.

In the general formulas (2) and (3), R ₁ , R ₂ , R ₄ , R ₅ , R ₆ , R ₇ , R ₉ and R ₁₀ are all hydrogen atoms, and at least one of R ₃ and R ₈ Is a halogen atom, an alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 8 carbon atoms, a haloalkoxy group having 1 to 8 carbon atoms, or a dialkylamino group having 2 to 16 carbon atoms (the alkyl groups are bonded to each other). A ring structure containing a nitrogen atom may be formed), and when it is not a halogen atom, an alkyl group, a haloalkyl group, a haloalkoxy group, or a dialkylamino group, it is preferably a hydrogen atom.
It is also preferable that at least one of R ₃ and R ₈ is a linear alkyl group having 1 to 12 carbon atoms.

In the present invention, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (4).

In General Formula (4), R _{1 to} R ₁₄ each represent the same group as R _{1 to} R ₁₀ in General Formula (1), and the same specific examples can be given, and R _{1 to} R ₅ , R ₆ to R ₁₀ , R _{11 to} R ₁₂ , and R _{13 to} R ₁₄ may be adjacent to each other to form a saturated or unsaturated cyclic structure, and specific examples similar to those described above can be given. Moreover, n is an integer of 1-20, and it is preferable in it being an integer of 1-5.
In the general formula (4), R _{11 to} R ₁₄ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 8 carbon atoms, or an alkoxy having 1 to 8 carbon atoms. Group, an alkylthio group having 1 to 8 carbon atoms, a dialkylamino group having 2 to 8 carbon atoms (the alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), alkylsulfonyl having 1 to 8 carbon atoms Group or a cyano group is preferred.

In the general formula (4), R ₁ , R ₂ , R ₄ , R ₅ , R ₆ , R ₇ and R _{9 to} R ₁₄ are all hydrogen atoms, and at least one of R ₃ and R ₈ is a halogen atom. An alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 8 carbon atoms, a haloalkoxy group having 1 to 8 carbon atoms, or a dialkylamino group having 2 to 16 carbon atoms (the alkyl groups are bonded to each other to form a nitrogen atom). And a hydrogen atom when it is not a halogen atom, an alkyl group, a haloalkyl group, a haloalkoxy group, or a dialkylamino group. In the above, it is also preferable that at least one of R ₃ and R _{8 is} a linear alkyl group having 1 to 12 carbon atoms.
Further, in the general formula (4), one of R ₁ to R ₁₄ is a fluorine atom, a cyano group, a trifluoromethyl group, or is a pentafluoroethyl group.

In the present invention, the compound represented by the general formula (1) is preferably a compound represented by the following general formula (5).

R _{1 to} R ₁₀ are the same as in formula (1).
R _{15 to} R ₂₂ are each independently a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or a haloalkoxy group having 1 to 30 carbon atoms. An alkylthio group having 1 to 30 carbon atoms, a haloalkylthio group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, a dialkylamino group having 2 to 30 carbon atoms (the alkyl groups are bonded to each other to form a nitrogen atom) A ring structure that includes 1 to 30 carbon atoms, a haloalkylsulfonyl group having 1 to 30 carbon atoms, an aromatic hydrocarbon group having 6 to 60 carbon atoms, and an aromatic group having 1 to 60 carbon atoms. A group heterocyclic group, an alkylsilyl group having 3 to 30 carbon atoms, or a cyano group, and each of these groups may have a substituent. Specific examples of these groups include those of the general formula (1). R ₁ ~R ₀ include the same specific examples as.
R _{1 to} R ₅ and R _{6 to} R ₁₀ may be adjacent to each other to form a saturated cyclic structure, and specific examples of the cyclic structure include the same specific examples as described above.
In the general formula (5), R ₁ , R ₂ , R ₄ , R ₅ , R ₆ , R ₇ , R ₉ , R ₁₀ and R _{15 to} R ₂₂ are all hydrogen atoms, and at least R ₃ and R ₈ One is a halogen atom, an alkyl group having 1 to 12 carbon atoms (particularly a linear alkyl group), a haloalkyl group having 1 to 8 carbon atoms, a haloalkoxy group having 1 to 8 carbon atoms, or a dialkyl having 2 to 16 carbon atoms. An amino group (the alkyl group may be bonded to each other to form a ring structure containing a nitrogen atom), and if not a halogen atom, an alkyl group, a haloalkyl group, a haloalkoxy group, or a dialkylamino group, It is preferable.
Furthermore, in General formula (5), it is preferable that any of R _{1 to} R ₂₂ is a fluorine atom, a cyano group, a trifluoromethyl group, or a pentafluoroethyl group.

Hereinafter, although the specific example of the compound represented by General formula (1), (4) and (5) used for the organic-semiconductor layer of the organic thin-film transistor of this invention is given, it is not limited to these.

The compound represented by the formula (1) preferably has an ionization potential of 5.2 eV or more, more preferably 5.3 eV or more. Moreover, the upper limit of the ionization potential of the compound represented by Formula (1) is 7.0 eV, for example.
When the ionization potential of the compound represented by formula (1) is 5.2 eV or more, it is difficult to oxidize and has high atmospheric stability.
The ionization potential can be measured by, for example, photoelectron spectroscopy or cyclic voltammetry.

  In an electronic device such as the organic thin film transistor of the present invention, a device having a high field effect mobility and a high on / off ratio can be obtained by using a material having high purity. Therefore, it is desirable to purify the compound represented by the formula (1) by a technique such as column chromatography, recrystallization, distillation, sublimation, etc., if necessary. Preferably, it is possible to improve the purity by repeatedly using these purification methods or combining a plurality of methods. Furthermore, it is desirable to repeat sublimation purification at least twice or more as the final step of purification as necessary. By using these techniques, it is preferable to use a material having a purity of 90% or more, more preferably 95% or more, particularly preferably 99% or more of the compound represented by the formula (1) measured by HPLC. Accordingly, there is a possibility that the field effect mobility and the on / off ratio of the organic thin film transistor can be increased and the driving voltage can be lowered to bring out the performance inherent to the material.

Hereinafter, the element structure of the organic thin-film transistor of this invention is demonstrated.
As an element configuration of the organic thin film transistor of the present invention, at least three terminals of a gate electrode, a source electrode, and a drain electrode, an insulator layer, and an organic semiconductor layer are provided on a substrate, and charge is injected between the organic semiconductor layer and the source-drain. Any thin film transistor may be used as long as it is a thin film transistor in which a layer is provided and the source-drain current is controlled by applying a voltage to the gate electrode. Among these, the elements A to D are shown in FIGS. As described above, several configurations are known depending on the position of the electrode, the layer stacking order, and the like, and the organic thin film transistor of the present invention has a field effect transistor (FET) structure. The organic thin film transistor is formed with an organic semiconductor layer (organic compound layer), a source electrode and a drain electrode formed to face each other with a predetermined distance, and a predetermined distance from the source electrode and the drain electrode. And a current flowing between the source and drain electrodes is controlled by applying a voltage to the gate electrode. Here, the distance between the source electrode and the drain electrode is determined by the use of the organic thin film transistor of the present invention, and is usually 0.1 μm to 1 mm, preferably 1 μm to 100 μm, and more preferably 5 μm to 100 μm.

  Of the elements A to D, the element C of FIG. 4 will be described in more detail as an example. The organic thin film transistor 4 of the element C includes a gate electrode 70 and an insulator layer 60 on the substrate 10 in this order. An organic semiconductor layer 50 is formed on 60, and has a pair of a source electrode 20 and a drain electrode 30 formed on the organic semiconductor layer 50 with a predetermined gap therebetween. Further, the source electrode 20, the drain electrode 30, and the organic semiconductor layer 50 are provided. The charge injection layer 40 is inserted between the two. The organic semiconductor layer 50 forms a channel region, and is turned on / off by controlling a current flowing between the source electrode 20 and the drain electrode 30 with a voltage applied to the gate electrode 70. In the present invention, the charge injection layer 40 containing the compound represented by the formula (1) is stacked between the source electrode 20 and the organic semiconductor layer 50 and between the drain electrode 30 and the organic semiconductor layer 50, whereby the source electrode 20, the contact resistance between the drain electrode 30 and the organic semiconductor layer 50 can be reduced, and the drive voltage can be reduced.

(Organic semiconductor layer)
The organic semiconductor used in the present invention is not particularly limited. Organic semiconductors used for organic TFTs as generally disclosed can be used.
Specific examples are shown below.

(Materials used for organic semiconductor layers)
Since high field effect mobility can be obtained, a crystalline material is usually used. Specifically, the following materials can be exemplified.
(1) Acenes which may be substituted, such as naphthalene, anthracene, tetracene, pentacene, hexacene, heptacene, such as 1,4-bisstyrylbenzene, 1,4-bis (2-methylstyryl) benzene, 1 , 4-bis (3-methylstyryl) benzene (4MSB), 1,4-bis (4-methylstyryl) benzene, polyphenylene vinylene and the like, a styryl structure represented by C ₆ H ₅ —CH═CH—C ₆ H ₅ (2) Compounds containing a thiophene ring shown below (a) Substitution of α-4T, α-5T, α-6T, α-7T, α-8T derivatives, etc. Thiophene oligomer which may have a group (a) Polyhexylthiophene, poly (9,9-dioctylfluorenyl-2,7-diyl-co-bithio (U) Bisbenzothiophene derivatives, α, α′-bis (dithieno [3,2-b: 2 ′, 3′-d] thiophene), dithieno Thiophene-thiophene co-oligomer, condensed oligothiophene such as pentathienoacene, especially compound having thienobenzene skeleton or dithienobenzene skeleton, benzothienobenzothiophene derivative (3), selenophene oligomer, metal-free phthalocyanine, copper phthalocyanine, lead Porphyrins such as phthalocyanine, titanyl phthalocyanine, platinum porphyrin, porphyrin, benzoporphyrin, tetrathiafulvalene (TTF) and its derivatives, rubrene and its derivatives, etc. (4) tetracyanoquinodimethane (TCNQ), 11, 11, 12, 12-Tet Quinoid oligomers such as cyanonaphth-2,6-quinodimethane (TCNNQ), fullerenes such as C60, C70, PCBM, N, N′-diphenyl-3,4,9,10-perylenetetracarboxylic acid diimide, N, N ′ -Tetracarboxylic acids such as dioctyl-3,4,9,10-perylenetetracarboxylic acid diimide (C8-PTCDI), NTCDA, 1,4,5,8-naphthalenetetracarboxylic diimide (NTCDI), and the like.
In addition, it is preferable that the material used for an organic-semiconductor layer is a material different from the material used for the charge injection layer mentioned later.

(substrate)
The substrate in the organic thin film transistor of the present invention plays a role of supporting the structure of the organic thin film transistor. As a material, in addition to glass, inorganic compounds such as metal oxides and nitrides, plastic films (PET, PES, PC) It is also possible to use metal substrates or composites or laminates thereof. Further, when the structure of the organic thin film transistor can be sufficiently supported by the components other than the substrate, it is possible not to use the substrate. Further, a silicon (Si) wafer is often used as a material for the substrate. In this case, Si itself can be used as the gate electrode / substrate 12 shown in FIG. It is also possible to oxidize the surface of Si to form SiO ₂ and use it as the insulator layer 62. In this case, as shown in FIG. 6, a metal layer such as Au may be formed on the Si substrate 12 serving as a substrate and gate electrode as an electrode for connecting a lead wire.

(electrode)
In the organic thin film transistor of the present invention, the material for the gate electrode, the source electrode and the drain electrode is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony, lead , Tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin oxide, indium tin oxide (ITO), fluorine-doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste And carbon paste, lithium, beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium-potassium alloy, magnesium / copper mixture, magnesium / silver mixture, Magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, a lithium / aluminum mixture, etc. are used, it forms a film by sputtering or vacuum deposition method.

In the organic thin film transistor of the present invention, as the source electrode and the drain electrode, those formed using a fluid electrode material such as a solution, paste, ink, or dispersion liquid containing the above conductive material can be used. Further, the solvent or dispersion medium is preferably a solvent or dispersion medium containing 60% by mass or more, preferably 90% by mass or more of water, in order to suppress damage to the organic semiconductor. As the dispersion containing metal fine particles, for example, a known conductive paste or the like may be used, but a dispersion containing metal fine particles usually having a particle size of 0.5 nm to 50 nm, 1 nm to 10 nm is preferable. . Examples of the material of the fine metal particles include platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten. Zinc or the like can be used.
It is also preferable to form an electrode using a dispersion in which these metal fine particles are dispersed in water or a dispersion medium which is an arbitrary organic solvent using a dispersion stabilizer mainly composed of an organic material. As a method for producing such a dispersion of metal fine particles, metal ions can be reduced in the liquid phase, such as a physical generation method such as gas evaporation method, sputtering method, metal vapor synthesis method, colloid method, coprecipitation method, etc. And a chemical production method for producing metal fine particles, preferably disclosed in JP-A-11-76800, JP-A-11-80647, JP-A-11-319538, JP-A-2000-239853, and the like. Colloidal method, gas evaporation method described in JP-A-2001-254185, 2001-53028, 2001-35255, 2000-124157, 2000-123634, etc. This is a dispersion of produced metal fine particles.
After forming the electrode using these metal fine particle dispersions and drying the solvent, if necessary, by heating to a shape in the range of 100 ° C to 300 ° C, preferably 150 ° C to 200 ° C, Metal fine particles are thermally fused to form an electrode pattern having a desired shape.

  Furthermore, it is also preferable to use a known conductive polymer whose conductivity has been improved by doping or the like as a material for the gate electrode, the source electrode, and the drain electrode. A polystyrene sulfonic acid complex or the like is also preferably used.

Of the above-described examples, the material for forming the source electrode and the drain electrode is preferably a material having low electrical resistance on the contact surface with the charge injection material. The electrical resistance at this time corresponds to the field effect mobility when the current control device is manufactured as described above, and the resistance needs to be as small as possible in order to obtain a large field effect mobility. There are various factors of contact resistance. For example, the adhesion force between the electrode and the organic compound, the adhesion area, the interaction at the interface between the electrode and the organic compound (polarization at the interface, charge transfer, mirror image effect, etc.). Of particular importance is the magnitude relationship between the work function of the electrode material and the energy level of the charge injection layer.
When the work function (W) of the electrode material is a, the ionization potential of the charge injection layer is (Ip) is b, and the electron affinity (Af) of the charge injection layer is c, it is preferable that the following relational expression is satisfied. Here, a, b, and c are all positive values with reference to the vacuum level.

In the case of a p-type organic thin film transistor, it is preferable that ba <1.5 eV (formula (I)), and more preferably ba <1.0 eV. If the above relationship can be maintained in relation to the charge injection layer, a high-performance device can be obtained. In particular, the work function of the electrode material is preferably as large as possible, and the work function is preferably 4.0 eV or more. More preferably, the work function is 4.2 eV or more.
The value of the work function of the metal is, for example, an effective metal having a work function of 4.0 eV or more described in Chemical Handbook II-493 (revised 3 edition, published by the Chemical Society of Japan, Maruzen Co., Ltd. 1983). The high work function metal is mainly Ag (4.26, 4.52, 4.64, 4.74 eV), Al (4.06, 4.24, 4.41 eV), Au (5.1, 5.37, 5.47 eV), Be (4.98 eV), Bi (4.34 eV), Cd (4.08 eV), Co (5.0 eV), Cu (4.65 eV), Fe (4.5, 4.67, 4.81 eV), Ga (4.3 eV), Hg (4.4 eV), Ir (5.42, 5.76 eV), Mn (4.1 eV), Mo (4 .53, 4.55, 4.95 eV), Nb (4.02, 4.36). 4.87 eV), Ni (5.04, 5.22, 5.35 eV), Os (5.93 eV), Pb (4.25 eV), Pt (5.64 eV), Pd (5.55 eV), Re ( 4.72 eV), Ru (4.71 eV), Sb (4.55, 4.7 eV), Sn (4.42 eV), Ta (4.0, 4.15, 4.8 eV), Ti (4.33 eV) ), V (4.3 eV), W (4.47, 4.63, 5.25 eV), Zr (4.05 eV). Among these, noble metals (Ag, Au, Cu, Pt), Ni, Co, Os, Fe, Ga, Ir, Mn, Mo, Pd, Re, Ru, V, and W are preferable. Other than metals, conductive polymers such as ITO, polyaniline and PEDOT: PSS and carbon are preferred. Even if one or more of these high work function substances are included as the electrode material, there is no particular limitation as long as the work function satisfies the formula (I).

In the case of an n-type organic thin film transistor, it is preferable that ac <1.5 eV (formula (II)), and more preferably ac <1.0 eV. If the above relationship can be maintained in relation to the charge injection layer, a high-performance device can be obtained. In particular, the work function of the electrode material is preferably as small as possible, and the work function is preferably 4.3 eV or less. More preferably, the work function is 3.7 eV or less.
As a specific example of the low work function metal, for example, it has a work function of 4.3 eV or less as described in Chemical Handbook Basics, pages II-493 (revised 3 edition, published by the Chemical Society of Japan, Maruzen Co., Ltd. 1983). What is necessary is just to select from the said list | wrist of a metal, Ag (4.26 eV), Al (4.06, 4.28 eV), Ba (2.52 eV), Ca (2.9 eV), Ce (2.9 eV), Cs (1.95 eV), Er (2.97 eV), Eu (2.5 eV), Gd (3.1 eV), Hf (3.9 eV), In (4.09 eV), K (2.28 eV), La ( 3.5 eV), Li (2.93 eV), Mg (3.66 eV), Na (2.36 eV), Nd (3.2 eV), Rb (4.25 eV), Sc (3.5 eV), Sm (2 .7 eV), Ta (4.0, 4.15 eV), Y (3.1 eV), Yb (2.6 eV), Zn (3.63 eV) and the like. Among these, Ba, Ca, Cs, Er, Eu, Gd, Hf, K, La, Li, Mg, Na, Nd, Rb, Y, Yb, and Zn are preferable. Even if one or more of these low work function substances are included as the electrode material, there is no particular limitation as long as the work function satisfies the above formula (II). However, since the low work function metal easily deteriorates when exposed to moisture and oxygen in the atmosphere, it is desirable to coat with a stable metal in the air such as Ag or Au as necessary. The film thickness necessary for the coating is 10 nm or more, and as the film thickness increases, the film can be protected from oxygen and water. However, for practical reasons, the thickness is preferably 1 μm or less for the purpose of increasing productivity.

The electrode may be formed by means such as vapor deposition, electron beam vapor deposition, sputtering, atmospheric pressure plasma method, ion plating, chemical vapor deposition, electrodeposition, electroless plating, spin coating, printing or ink jet. Is done. In addition, as a method of patterning as necessary, a conductive thin film formed using the above method is formed using a known photolithographic method or a lift-off method, on a metal foil such as aluminum or copper. There is a method in which a resist is formed and etched by thermal transfer, ink jet, or the like. Alternatively, a conductive polymer solution or dispersion, a dispersion containing metal fine particles, or the like may be directly patterned by an ink jet method, or may be formed from a coating film by lithography, laser ablation, or the like. Further, a method of patterning a conductive ink or conductive paste containing a conductive polymer or fine metal particles by a printing method such as relief printing, intaglio printing, lithographic printing, or screen printing can also be used.
The thickness of the electrode formed in this way is not particularly limited as long as current conduction is present, but it is preferably in the range of 0.2 nm to 10 μm, more preferably 4 nm to 300 nm. If it is in this preferable range, the resistance is increased due to the thin film thickness, and a voltage drop does not occur. In addition, since the film is not too thick, it does not take time to form the film, and when another layer such as a protective layer or an organic semiconductor layer is laminated, the laminated film can be smooth without causing a step.
In the organic thin film transistor of this embodiment, for example, a buffer layer may be provided between the charge injection layer and the source and drain electrodes for the purpose of further improving the charge injection efficiency. The buffer layer has an alkali metal or alkaline earth metal ion bond such as LiF, Li ₂ O, CsF, NaCO ₃ , KCl, MgF ₂ , and CaCO ₃ used for an organic EL cathode for an n-type organic thin film transistor. Compounds are desirable. Moreover, you may insert the compound used as an electron injection layer and an electron carrying layer by organic EL, such as Alq.
For p-type organic thin film transistors, cyano compounds such as FeCl ₃ , TCNQ, F 4 -TCNQ, HAT, CFx, GeO ₂ , SiO ₂ , MoO ₃ , V ₂ O ₅ , VO ₂ , V ₂ O ₃ , MnO, Mn ₃ O ₄ , ZrO ₂ , WO ₃ , TiO ₂ , In ₂ O ₃ , ZnO, NiO, HfO ₂ , Ta ₂ O ₅ , ReO ₃ , metal oxides other than alkaline earth metals, such as PbO ₂ , Inorganic compounds such as ZnS and ZnSe are desirable. In many cases, these oxides cause oxygen vacancies, which are suitable for hole injection. Further, amine compounds such as TPD and NPD, and compounds used as a hole injection layer and a hole transport layer in an organic EL device such as CuPc may be used. Moreover, what consists of two or more types of said compounds is desirable.

(Insulator layer)
The material of the insulator layer in the organic thin film transistor of the present invention is not particularly limited as long as it has electrical insulation and can be formed as a thin film. Metal oxide (including silicon oxide), metal nitride ( (Including silicon nitride), polymers, low molecular organic molecules, and the like, materials having an electrical resistivity at room temperature of 10 Ωcm or more can be used, and an inorganic oxide film having a high relative dielectric constant is particularly preferable.
Inorganic oxides include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, Barium titanate, barium magnesium fluoride, lanthanum oxide, fluorine oxide, magnesium oxide, bismuth oxide, bismuth titanate, niobium oxide, strontium bismuth titanate, strontium bismuth tantalate, tantalum pentoxide, niobium tantalate Examples thereof include bismuth acid, trioxide yttrium, and combinations thereof, and silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide are preferable.
In addition, inorganic nitrides such as silicon nitride (Si ₃ N ₄ , SixNy (x, y> 0)) and aluminum nitride can be suitably used.

Further, the insulator layer may be formed of a precursor containing an alkoxide metal, and the insulator layer is formed by coating a solution of the precursor on a substrate, for example, and subjecting the solution to a chemical solution treatment including heat treatment. It is formed.
The metal in the alkoxide metal is selected from, for example, a transition metal, a lanthanoid, or a main group element. Specifically, barium (Ba), strontium (Sr), titanium (Ti), bismuth (Bi), tantalum ( Ta), zircon (Zr), iron (Fe), nickel (Ni), manganese (Mn), lead (Pb), lanthanum (La), lithium (Li), sodium (Na), potassium (K), rubidium ( Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), niobium (Nb), thallium (Tl), mercury (Hg), copper (Cu), cobalt ( Co), rhodium (Rh), scandium (Sc), yttrium (Y), and the like. Examples of the alkoxide in the alkoxide metal include, for example, alcohols including methanol, ethanol, propanol, isopropanol, butanol, isobutanol, methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, pentoxyethanol, heptoxyethanol, Examples thereof include those derived from alkoxy alcohols including methoxypropanol, ethoxypropanol, propoxypropanol, butoxypropanol, pentoxypropanol, heptoxypropanol, and the like.

In the present invention, when the insulator layer is made of the above-described material, polarization easily occurs in the insulator layer, and the threshold voltage for transistor operation can be reduced. In addition, among the above materials, the insulator layer can be formed of silicon nitride such as Si ₃ N ₄ , SixNy, and SiONx (x, y> 0).
As an insulator layer using an organic compound, polyimide, polyamide, polyester, polyacrylate, photo radical polymerization system, photo cation polymerization system photo-curing resin, copolymer containing acrylonitrile component, polyvinyl alcohol, novolac resin, Also, cyanoethyl pullulan or the like can be used.

In addition, wax, polyethylene, polychloropyrene, polyethylene terephthalate, polyoxymethylene, polyvinyl chloride, polyvinylidene fluoride, polysulfone, polyimide cyanoethyl pullulan, poly (vinylphenol) (PVP), poly (methyl methacrylate) (PMMA), polycarbonate ( In addition to PC), polystyrene (PS), polyolefin, polyacrylamide, poly (acrylic acid), novolac resin, resole resin, polyimide, polyxylylene, epoxy resin, high molecular materials with high dielectric constant such as pullulan may be used. Is possible.
As the organic compound material or polymer material used for the insulator layer, an organic compound having water repellency is particularly preferable. By having water repellency, the interaction between the insulator layer and the organic semiconductor layer is suppressed, Utilizing the inherent cohesion, the crystallinity of the organic semiconductor layer can be increased and the device performance can be improved. Examples of such compounds include polyparaxylylene derivatives described in Yasuda et al. Jpn. J. Appl. Phys. Vol. 42 (2003) pp. 6614-6618 and Janos Veres et al. Chem. Mater., Vol. 16 (2004). ) The thing of pp.4543-4555 is mentioned.
Further, when such a top gate structure as shown in FIGS. 2 and 5 is used, if such an organic compound is used as a material for the insulator layer, the film can be formed with reduced damage to the organic semiconductor layer. Therefore, it is an effective method.

  The pre-insulator layer may be a mixed layer using a plurality of inorganic or organic compound materials as described above, or may be a laminated structure thereof. In this case, the performance of the device can be controlled by mixing or laminating a material having a high dielectric constant and a material having water repellency, if necessary.

The insulator layer may include an anodic oxide film or the anodic oxide film as a configuration. The anodized film is preferably sealed. The anodized film is formed by anodizing a metal that can be anodized by a known method. Examples of the metal that can be anodized include aluminum and tantalum, and the anodizing method is not particularly limited, and a known method can be used. An oxide film is formed by anodizing. Any electrolyte solution that can form a porous oxide film can be used as the anodizing treatment. Generally, sulfuric acid, phosphoric acid, oxalic acid, chromic acid, boric acid, sulfamic acid, benzenesulfone, and the like can be used. An acid or the like or a mixed acid obtained by combining two or more of these or a salt thereof is used. The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. In general, the electrolyte concentration is 1 to 80% by mass, the electrolyte temperature is 5 to 70 ° C., and the current density. 0.5 to 60 a / cm ^2, voltage 1 to 100 V, the electrolysis time of 10 seconds to 5 minutes is suitable. A preferred anodizing treatment is a method in which an aqueous solution of sulfuric acid, phosphoric acid or boric acid is used as the electrolytic solution and the treatment is performed with a direct current, but an alternating current can also be used. The concentration of these acids is preferably 5 to 45% by mass, and the electrolytic treatment is preferably performed for ²⁰ to 250 seconds at an electrolyte temperature of 20 to 50 ° C. and a current density of 0.5 to 20 A / cm ² .
As the thickness of the insulator layer, if the layer thickness is thin, the effective voltage applied to the organic semiconductor increases, so the drive voltage and threshold voltage of the device itself can be lowered, but conversely the leakage between the source and gate Since the current increases, it is necessary to select an appropriate film thickness, which is usually 1 nm to 5 μm, preferably 5 nm to 2 μm, and more preferably 100 nm to 1 μm.

  Moreover, you may perform arbitrary orientation processing between the said insulator layer and an organic-semiconductor layer. A preferable example thereof is a method for improving the crystallinity of the organic semiconductor layer by reducing the interaction between the insulator layer and the organic semiconductor layer by performing a water repellent treatment or the like on the surface of the insulator layer. A silane coupling agent such as octadecyltrichlorosilane, trichloromethylsilazane, or a self-organized alignment film material such as alkane phosphoric acid, alkane sulfonic acid, or alkane carboxylic acid is brought into contact with the insulating film surface in a liquid phase or gas phase. An example is a method of appropriately drying after forming the self-assembled film. In addition, a method in which a film made of polyimide or the like is provided on the surface of the insulating film and the surface is rubbed so as to be used for liquid crystal alignment is also preferable.

  As a method for forming the insulator layer, 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, JP-A-11-61406, 11-133205, JP-A 2000-121804, 2000-147209, 2000-185362, etc., dry process such as atmospheric pressure plasma method, spray coating method, spin coating method, blade coating Examples thereof include wet processes such as a method by coating such as a method, a dip coating method, a cast method, a roll coating method, a bar coating method, and a die coating method, and a patterning method such as printing and ink jetting. The wet process is a method of applying and drying a liquid in which fine particles of inorganic oxide are dispersed in an arbitrary organic solvent or water using a dispersion aid such as a surfactant as required, or an oxide precursor, for example, A so-called sol-gel method in which a solution of an alkoxide body is applied and dried is used.

Although the film thickness of the organic-semiconductor layer in the organic thin-film transistor of this invention is not restrict | limited in particular, Usually, it is 0.5 nm-1 micrometer, and it is preferable in it being 2 nm-250 nm.
In addition, a method for forming the organic semiconductor layer is not particularly limited, and a known method can be applied. For example, molecular beam deposition (MBE), vacuum deposition, chemical deposition, dipping of a solution in which a material is dissolved in a solvent Organic, as described above, by means of printing, spin coating, casting, bar coating, roll coating, etc., coating and baking, electropolymerization, self-assembly from solution, and combinations thereof It is made of a semiconductor layer material.
When the crystallinity of the organic semiconductor layer is improved, the field effect mobility is improved. Therefore, when film formation from a gas phase (evaporation, sputtering, etc.) is used, it is desirable to maintain the substrate temperature during film formation at a high temperature. The temperature is preferably 50 to 250 ° C, and more preferably 70 to 150 ° C. In addition, it is preferable to perform annealing after film formation regardless of the film forming method because a high-performance device can be obtained. The annealing temperature is preferably 50 to 200 ° C, more preferably 70 to 200 ° C, and the time is preferably 10 minutes to 12 hours, more preferably 1 to 10 hours.

In the present invention, for the charge injection layer, one kind of material selected from the general formula (1), (4) or (5) may be used, or a plurality of known materials such as pentacene and thiophene oligomer may be combined. A mixed thin film made of a plurality of materials, a layer made of these materials alone, or a mixed film may be laminated and used. Further, different charge injection layers may be provided for the source electrode and the drain electrode, respectively. The film thickness of the charge injection layer is preferably 0.1 nm to 1 μm, more preferably 0.3 nm to 100 nm, and a film formation method similar to that of the organic semiconductor layer can be used.
Further, as shown in 42 of FIG. 7, the charge injection layer may be provided in a portion where the source-drain electrode is not provided between the organic semiconductor layer 52 and the source-drain electrode. In this case, the charge injection layer can be installed without using a metal mask, which is advantageous in terms of productivity.

A method for forming the organic thin film transistor of the present invention is not particularly limited and may be a known method. According to a desired element configuration, the substrate is charged, the gate electrode is formed, the insulator layer is formed, the organic semiconductor layer is formed, and the charge injection layer It is preferable to form a series of device manufacturing steps from formation, source electrode formation, and drain electrode formation without exposure to the atmosphere, because the device performance can be prevented from being impaired by moisture, oxygen, etc. in the atmosphere due to contact with the atmosphere. When it is unavoidable that the atmosphere must be exposed to the atmosphere once, the process after the organic semiconductor layer is formed is not exposed to the atmosphere at all. In the case of B, the surface on which the source electrode and the drain electrode are partially stacked on the insulating layer) is cleaned and activated by ultraviolet irradiation, ultraviolet / ozone irradiation, oxygen plasma, argon plasma, etc., and then the organic semiconductor layer is stacked. It is preferable.
Further, for example, in consideration of the influence on the organic semiconductor layer such as oxygen and water contained in the atmosphere, a gas barrier layer may be formed on the whole or a part of the outer peripheral surface of the organic thin film transistor element. As the material for forming the gas barrier layer, those commonly used in this field can be used, and examples thereof include polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl chloride, polyvinylidene chloride, and polychlorotrifluoroethylene. . Furthermore, the inorganic substance which has the insulation illustrated in the said insulator layer can also be used.

The present invention also provides an organic thin film light emitting transistor that controls light emission by obtaining light emission using a current flowing between a source and a drain and applying a voltage to a gate electrode.
The organic thin film transistor according to the present invention can also be used as a light emitting element using charges injected from the source and drain electrodes. That is, the organic thin film transistor can be used as an organic thin film light emitting transistor that also functions as a light emitting element (organic EL). In this case, the emission intensity can be controlled by controlling the current flowing between the source and drain electrodes with the gate electrode. Since the transistor for controlling light emission and the light emitting element can be integrated, the aperture ratio of the display can be improved and the cost can be reduced by the simplification of the manufacturing process, which provides a great practical advantage. When used as an organic light-emitting transistor, the contents described in the above detailed description are sufficient, but in order to operate the organic thin-film transistor of the present invention as an organic light-emitting transistor, holes from one of the source and drain and electrons from the other are used. In order to improve the light emission performance, it is preferable to satisfy the following conditions.

(Source, drain)
In the organic thin film light emitting transistor of the present invention, at least one of them is preferably a hole injecting electrode in order to improve hole injecting property. A hole injection electrode is an electrode containing a substance having a work function of 4.2 eV or higher.
In order to improve the electron injection property, at least one of them is preferably an electron injection electrode. An electron injecting electrode is an electrode containing a substance having a work function of 4.3 eV or less. More preferably, it is an organic thin film light-emitting transistor provided with an electrode in which one is hole-injecting and the other is electron-injecting.

  More preferably, it is an organic thin film light emitting transistor provided with a hole injection layer under one electrode and an electron injection layer under the other electrode.

Next, the present invention will be described in more detail using examples.
Synthesis Example 1 (Synthesis of Compound (1))
The compound (1) was synthesized according to the following synthesis route.

  In a 300 ml three-necked flask, 7.50 g (31.7 mmol) of 1,4-dibromobenzene, 1.83 g (1.59 mmol) of tetrakistriphenylphosphine palladium, 0.604 g (3.17 mmol) of copper (I) iodide ) And replaced with argon. To this, 150 ml of triethylamine and 10.5 ml (95.4 mmol) of ethynylbenzene were added and heated to reflux for 9 hours under an argon atmosphere. 100 ml of water and 100 ml of methylene chloride were added to the reaction solution, and the organic layer was separated and dried over anhydrous magnesium sulfate. After concentration under reduced pressure with an evaporator, the obtained solid was purified by silica gel column chromatography (elution solvent: methylene chloride / hexane = 1/10) to obtain 2.55 g (9.16 mmol, yield 29) of compound (1). %)Obtained.

It was confirmed by ¹ H-NMR (90 MHz) and FD-MS (field desorption mass analysis) that the obtained compound was compound (1).
The measurement results of FD-MS are shown below.
_{FD-MS, calcd for C 48} H 30 S 2 = 278, found, m / z = 278 (M +, 100)
Moreover, as a result of sublimation purification of the compound (1) at 220 ° C., the purity of the compound (1) obtained by sublimation purification was 99.5%.

The apparatus and measurement conditions used for the FD-MS (field desorption mass analysis) measurement are shown below.
<FD-MS measurement>
Device: HX110 (manufactured by JEOL Ltd.)
Condition: Acceleration voltage 8kV
Scan range m / z = 50-1500

Example 1 (Production of organic thin film transistor)
A surface of a Si substrate (also used as a P-type specific resistance 1 Ωcm gate electrode) was oxidized by a thermal oxidation method, and a 300 nm thermal oxide film was formed on the substrate to form an insulator layer. Further, after the SiO ₂ film formed on one side of the substrate is completely removed by dry etching, chromium is deposited to a thickness of 20 nm by sputtering, and further gold (Au) is sputtered by 100 nm by sputtering. A film was formed and taken out as an electrode.
This substrate was ultrasonically cleaned with a neutral detergent, pure water, acetone and ethanol for 30 minutes each, and further subjected to ozone cleaning.

  Next, the substrate was placed in a vacuum vapor deposition apparatus (ULVAC, EX-400), and 1,4-bis (4-methylstyryl) benzene (4MSB) was vapor-deposited at 0.05 nm / s on the insulator layer. The film was formed as an organic semiconductor layer having a thickness of 50 nm at a speed. Next, a charge injection layer having a thickness of 20 nm was formed from the compound (1) prepared in Synthesis Example 1 through a metal mask at a deposition rate of 0.05 nm / s. Further, by depositing gold with a film thickness of 50 nm, a charge injection layer and a source electrode and a drain electrode which are not in contact with each other were formed so that a distance (channel length L) was 75 μm. At that time, an organic thin film transistor was manufactured by forming a film so that the width of the source electrode and the drain electrode (channel width W) was 5 mm (see FIG. 6).

A gate voltage of 0 to −100 V was applied to the gate electrode of the obtained organic thin film transistor, and a current was applied by applying a voltage between the source and drain. In the obtained organic thin film transistor, electrons were induced in the channel region (between source and drain) of the organic semiconductor layer, and operated as a p-type transistor. As a result, the on / off ratio of the current between the source and drain electrodes in the current saturation region was 1 × 10 ⁶ .
The field effect mobility μ _S and the threshold voltage V _T of the holes of the organic thin film transistor were calculated from the formula (2). As a result, μ _S = 0.15 cm ² / Vs and V _T = −20V. Further, from the formula (1), the field effect mobility μ _L in the linear region was calculated to be μ _S = 0.15 cm ² / Vs.

  The output curve of the obtained organic thin film transistor is shown in FIG. From FIG. 8, it was found that the output curve is a straight line and the contact resistance is reduced in the region where the drain voltage is in the vicinity of 0V (the circled portion).

Example 2
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (42) instead of the compound (1). The results are shown in Table 1.

Example 3
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (162) instead of the compound (1). The results are shown in Table 1.

Example 4
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (9) instead of the compound (1). The results are shown in Table 1.

Example 5
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (43) instead of the compound (1). The results are shown in Table 1.

Example 6
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (60) instead of the compound (1). The results are shown in Table 1.

Example 7
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (70) instead of the compound (1). The results are shown in Table 1.

Example 8
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (110) instead of the compound (1). The results are shown in Table 1.

Example 9
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was formed using the compound (171) instead of the compound (1). The results are shown in Table 1.

Example 10
An organic semiconductor layer was formed using N, N′-dioxyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) instead of 1,4-bis (4-methylstyryl) benzene. Then, a compound (65) is used instead of the compound (1) to form a charge injection layer, and instead of Au, Ca is vacuum-deposited at a deposition rate of 0.05 nm / s to 20 nm, and then Ag is 0.05 nm / An organic thin film transistor was manufactured in the same manner as in Example 1 except that the source electrode and the drain electrode were formed by depositing 50 nm at a deposition rate of s and covering Ca.
Evaluation was performed in the same manner as in Example 1 except that a gate voltage of 0 to +100 V was applied to the gate electrode of the obtained organic thin film transistor to drive n-type. The results are shown in Table 1.

Example 11
Except that MoO ₃ was vacuum-deposited by 10 nm at a deposition rate of 0.05 nm / s and inserted as a buffer layer between the source and drain electrodes made of Au and the charge injection layer made of the compound (60), the same as in Example 6. Thus, an organic thin film transistor was manufactured and evaluated. The results are shown in Table 1.

Example 12
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 10 except that the charge injection layer was formed using the compound (163) instead of the compound (65). The results are shown in Table 1.

Example 13
Instead of depositing the compound (1), 0.5% by mass of the compound (174) is dissolved in toluene, and the solution is used to form a film by a spin coating method, followed by drying at 80 ° C. in a nitrogen atmosphere, thereby injecting charges. An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the layer was formed. The results are shown in Table 1.

Example 14
In the organic thin film transistor manufacturing process of Example 1, when the charge injection layer using the compound (1) was formed, the compound (1) was deposited at a deposition rate of 0.05 nm / s with a thickness of 10 nm without passing through the metal mask. A charge injection layer was formed to manufacture the transistor shown in FIG. The evaluation results of this element are shown in Table 1.

Comparative Example 1
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 1 except that the charge injection layer was not formed. The results are shown in Table 1.
Moreover, the output curve of the obtained organic thin-film transistor is shown in FIG. From FIG. 9, it was found that in the region where the drain voltage is near 0V (the part surrounded by a circle), the output curve is bent and deviates from the straight line, the contact resistance is large and deviates from the characteristic of the equation (1).

Comparative Example 2
An organic thin film transistor was manufactured and evaluated in the same manner as in Example 10 except that the charge injection layer was not formed. The results are shown in Table 1.

Example 15 (Production of Organic Thin Film Light-Emitting Transistor)
The surface of a Si substrate (also used as a P-type specific resistance 1 Ωcm gate electrode) was oxidized by a thermal oxidation method to produce a 300 nm thermal oxide film on the substrate to form an insulator layer. Further, after the SiO ₂ film formed on one side of the substrate is completely removed by dry etching, chromium is deposited to a thickness of 20 nm by sputtering, and further gold (Au) is sputtered by 100 nm by sputtering. A film was formed and used as an extraction electrode.
This substrate was ultrasonically cleaned with a neutral detergent, pure water, acetone and ethanol for 30 minutes each.

Next, it is installed in a vacuum deposition apparatus (ULVAC, EX-900), and 4 MSB is deposited on the insulator layer (SiO ₂ ) as a 100 nm thick organic semiconductor light emitting layer at a deposition rate of 0.05 nm / s. did. Next, a metal mask having a channel length of 75 μm and a channel width of 5 mm was installed, and a compound (180) was deposited as a charge injection layer to a thickness of 10 nm at a deposition rate of 0.05 nm / s. Next, gold was deposited to a thickness of 50 nm through the mask in a state where the substrate was tilted 45 degrees with respect to the evaporation source. Next, by depositing Mg with a thickness of 100 nm in a state where the substrate is tilted 45 degrees in the opposite direction, the source electrode and the drain electrode which are not in contact with each other substantially form a hole injecting electrode (Au) and an electron transporting electrode (Mg). An organic thin film light emitting transistor provided was prepared.
When −100 V was applied between the source and drain electrodes of the manufactured organic thin film light-emitting transistor and −100 V was applied to the gate electrode, blue light emission of 50 cd / m ² was obtained.

Example 16 (Production of top contact type organic thin film transistor)
A top contact type organic thin film transistor having the structure shown in FIG. 4 was manufactured as follows.
Using a shadow mask, an ITO film having a thickness of 100 nm was formed on a glass substrate by sputtering to form a gate electrode. Further, poly (chloro-p-xylene) (parylene C) was formed thereon to a thickness of 500 nm by thermal chemical vapor deposition to form a gate insulating layer.

  Next, the substrate is placed in a vacuum deposition apparatus (ULVAC, EX-400), and 2,7-diphenyl [1] benzothieno [3,3-b]-[1] -benzothiophene is formed on the insulator layer. (DPh-BTBT) was deposited as an organic semiconductor layer having a thickness of 40 nm at a deposition rate of 0.05 nm / s at room temperature. Next, a charge injection layer having a thickness of 10 nm was formed from the compound (60) (2,6-bis (2-phenylethynyl) anthracene; DPEA) through a metal mask at a deposition rate of 0.05 nm / s. Further, by depositing gold with a film thickness of 50 nm, the charge injection layer and the source and drain electrodes which are not in contact with each other were formed so that the interval (channel length L) was 50 μm. At that time, an organic thin film transistor was manufactured by forming a film so that the width (channel width W) of the source electrode and the drain electrode was 1 mm (see FIG. 4).

About the obtained top contact type organic thin film transistor, a gate voltage of 0 to −25 V was applied to the gate electrode, and a current was applied by applying a voltage of −25 V between the source and the drain. Then, the hole field-effect mobility μ _s and the threshold voltage V _t were calculated from the equation (2) regarding the saturation region characteristics. The results are shown in Table 2.

Comparative Examples 3 and 4
An organic thin film transistor was fabricated in the same manner as in Example 16 except that the charge injection layer was replaced with the compound shown in Table 2, and the field effect mobility μ _s and the threshold voltage V _t were determined. The results are shown in Table 2.

From the results of Table 2, the device of Example 16 employing the compound (60) (DPEA) in the charge injection layer is superior to the device of pentacene (Comparative Example 3) or MoO ₃ (Comparative Example 4) in field effect migration. Degree and threshold voltage are shown. In particular, when pentacene used as a general organic semiconductor is used for the charge injection layer, good field-effect mobility and threshold voltage are not obtained. It can be seen that the characteristics required for the material constituting the charge injection material layer are different.

The organic thin film transistor of the present invention has a high performance as a transistor in which a response speed (driving speed) is increased, an on / off ratio is large, and a driving voltage is lowered by using a compound having a specific structure as a charge injection layer. Yes, it can also be used as an organic thin film light emitting transistor capable of emitting light.
The organic thin film transistor of the present invention is used for display electronic devices such as electronic devices for thin film displays, wearable electronic devices such as plastic IC cards and information tags, medical devices such as biosensors, and measuring devices. Can do.

Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will appreciate that these exemplary embodiments and / or embodiments are substantially without departing from the novel teachings and advantages of the present invention. It is easy to make many changes to the embodiment. Accordingly, many of these modifications are within the scope of the present invention.
The entire contents of the documents described in this specification are incorporated herein by reference.

Claims (18)

In an organic thin film transistor in which at least three terminals of a gate electrode, a source electrode and a drain electrode, an insulator layer and an organic semiconductor layer are provided on a substrate, and a source-drain current is controlled by applying a voltage to the gate electrode.
A charge injection layer between the organic semiconductor layer and the source electrode and between the organic semiconductor layer and the drain electrode,
Look containing a compound wherein the charge injection layer is represented by the following formula (1), wherein the organic semiconductor layer and the charge injection layer, an organic thin film transistor comprised of different materials.

(In the formula, Ar ₁ is a substituent represented by the following formula (2).
Ar ₂ is a divalent aromatic hydrocarbon group having 6 to 60 carbon atoms which may have a substituent, or a divalent aromatic heterocyclic group having 2 to 60 carbon atoms which may have a substituent. It is.
Ar ₃ is a substituent represented by the following formula (3).
n is an integer of 1-20. )

( Wherein R ₁ , R ₂ , R _{4 to} R ₇ , R ₉ and R ₁₀ are hydrogen atoms, R ₃ and R ₈ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 30 carbon atoms, C1-30 haloalkyl group, C1-30 alkoxy group, C1-30 haloalkoxy group, C1-30 alkylthio group, C1-30 haloalkylthio group, C1 An alkylamino group having -30 carbon atoms, a dialkylamino group having 2-30 carbon atoms (two alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), an alkylsulfonyl group having 1-30 carbon atoms, A haloalkylsulfonyl group having 1 to 30 carbon atoms, an aromatic hydrocarbon group having 6 to 60 carbon atoms, an aromatic heterocyclic group having 1 to 60 carbon atoms, an alkylsilyl group having 3 to 30 carbon atoms, or a cyano group. Base of It may further have a substituent . 2. The organic thin film transistor according to claim 1, wherein Ar _{2 in the} formula (1) is a C 6-60 divalent aromatic hydrocarbon group which may have a substituent. The organic compound according to claim 1 or 2, wherein Ar _{2 in the} formula (1) is a divalent residue corresponding to benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene or pentacene which may have a substituent. Thin film transistor. _2. The organic thin film transistor according to claim 1, wherein Ar _{2 in the} formula (1) is a C 6-60 divalent condensed polycyclic aromatic heterocyclic group which may have a substituent. _{2 in} which Ar _{2 in the} formula (1) corresponds to pyrrole, pyridine, pyrimidine, imidazole, thiazole, dithienobenzene, benzothiadiazole, quinoline, benzothiophene, dibenzothiophene, benzofuran or dibenzofuran which may have a substituent. The organic thin film transistor according to claim 4, which is a valence residue.   N of the said Formula (1) is 1, The organic thin-film transistor in any one of Claims 1-5.   The organic thin film transistor according to any one of claims 1 to 5, wherein n in the formula (1) is an integer of 2 or more. In the formulas (2) and (3) , at least one of R ₃ and R ₈ is a halogen atom, an alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 8 carbon atoms, or a haloalkoxy group having 1 to 8 carbon atoms. Or a dialkylamino group having 2 to 16 carbon atoms (two alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), and R ₃ or R _{8 other} than these are hydrogen atoms Item 8. The organic thin film transistor according to any one of Items 1 to 7. The organic thin film transistor according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (4).

(Wherein R _{1 to} R ₁₀ and n are the same as those in the formula (1)).
R _{11 to} R ₁₄ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, or a haloalkoxy group having 1 to 30 carbon atoms. , An alkylthio group having 1 to 30 carbon atoms, a haloalkylthio group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, and a dialkylamino group having 2 to 30 carbon atoms (two alkyl groups are bonded to each other to form nitrogen A ring structure containing an atom), an alkylsulfonyl group having 1 to 30 carbon atoms, a haloalkylsulfonyl group having 1 to 30 carbon atoms, an aromatic hydrocarbon group having 6 to 60 carbon atoms, and 1 to 60 carbon atoms. An aromatic heterocyclic group, an alkylsilyl group having 3 to 30 carbon atoms, or a cyano group, and these groups may further have a substituent.
R ₁₁ and R ₁₂ and R ₁₃ and R ₁₄ may be bonded to each other to form a saturated or unsaturated cyclic structure. ) R _{11 to} R _{14 in the} formula (4) are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or 1 carbon atom. -8 alkyloxy group, dialkylamino group having 2 to 8 carbon atoms (two alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), alkylsulfonyl group having 1 to 8 carbon atoms, or cyano The organic thin film transistor according to claim 9 which is a group. Oite the formula (4), at least one of _{R 3} and _{R 8,} a halogen atom, an alkyl group having 1 to 12 carbon atoms, a haloalkyl group having 1 to 8 carbon atoms, haloalkoxy group having 1 to 8 carbon atoms, Or a dialkylamino group having 2 to 16 carbon atoms (two alkyl groups may be bonded to each other to form a ring structure containing a nitrogen atom), and R ₃ or R _{8 other} than these are hydrogen atoms. 9. The organic thin film transistor according to 9. The organic thin-film transistor according to claim 9 or 10, wherein any of R ₃ , R ₈ and R _{11 to} R _{14 in} the formula (4) is a fluorine atom, a cyano group, a trifluoromethyl group, or a pentafluoroethyl group.   N of said Formula (4) is 1, The organic thin-film transistor in any one of Claims 9-12.   The organic thin film transistor according to any one of claims 9 to 12, wherein n in the formula (4) is an integer of 2 or more. The organic thin film transistor according to claim 1, wherein the compound represented by the formula (1) is a compound represented by the following formula (5).

_(Wherein, R 1 _{to R 10} are the same as in the formula (1).
R _{15 to} R ₂₂ are each a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, a haloalkoxy group having 1 to 30 carbon atoms, and a carbon number. An alkylthio group having 1 to 30 carbon atoms, a haloalkylthio group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, and a dialkylamino group having 2 to 30 carbon atoms (the two alkyl groups are bonded to each other to contain a nitrogen atom) A ring structure may be formed), a C1-C30 alkylsulfonyl group, a C1-C30 haloalkylsulfonyl group, a C6-C60 aromatic hydrocarbon group, a C1-C60 aromatic It is a heterocyclic group, a C3-C30 alkylsilyl group, or a cyano group, and these groups may further have a substituent. ) Between the source electrode and the charge injection layer, and between the drain electrode and the charge injection layer, an organic thin film transistor according to any one of claims 1 to 15, each having a buffer layer. The organic thin film transistor according to any one of claims 1 to 16 , wherein light emission is obtained by using a current flowing between a source and a drain, and light emission is controlled by applying a voltage to a gate electrode. The organic thin film transistor according to any one of claims 1 to 17 , wherein an ionization potential of the compound represented by the formula (1) is 5.2 eV or more.

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