JPWO2009125721A1 - COMPOUND FOR ORGANIC THIN FILM TRANSISTOR AND ORGANIC THIN FILM TRANSISTOR - Google Patents

Abstract

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. In the organic thin film transistor and organic thin film transistor in which the semiconductor layer includes a specific organic compound having an aromatic hydrocarbon group or aromatic heterocyclic group and an acetylene structure at the center, light emission is obtained by using a current flowing between the source and the drain. An organic thin film light emitting transistor that controls light emission by applying a voltage to a gate electrode, and a compound suitable for the organic thin film light emitting transistor.

Description

  The present invention relates to a compound for an organic thin film transistor and an organic thin film transistor using the compound for an organic semiconductor layer.

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 the figure, a typical TFT has a gate electrode, an insulator layer, and an organic semiconductor layer in this order on a substrate, a source electrode formed on the organic semiconductor layer at a predetermined interval, and It has a drain electrode. 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, a CVD apparatus used for manufacturing such a TFT using silicon is very expensive, and a display device using the TFT. Such an increase in size has a problem in that it involves a significant increase in manufacturing costs. 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 thus there is a problem that a lightweight resin substrate cannot be used. there were.

In order to solve such a problem, a TFT using an organic substance instead of amorphous or polycrystalline silicon (hereinafter sometimes abbreviated as an organic TFT) 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, it is possible to increase the size of the element while suppressing an increase in manufacturing cost. Thus, the process temperature required for film formation can be made relatively low. For this reason, the organic TFT has an advantage that there are few restrictions when selecting a material to be used for the substrate, and its practical use is expected, and research reports have been actively made.
As organic semiconductors used for organic TFTs, materials for p-type FETs (field effect transistors) include polymers such as conjugated polymers and thiophenes, metal phthalocyanine compounds, condensed aromatic hydrocarbons such as pentacene, etc. Used in the form of a mixture with a compound. Moreover, as a material of n-type FET, for example, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), 11,11,12,12-tetracyanonaphtho-2,6-quinodimethane (TCNNQD) 1,4,5,8-naphthalenetetracarboxyldiimide (NTCDI) and fluorinated phthalocyanine are known.

On the other hand, there is an organic electroluminescence (EL) element as a device that similarly uses electric conduction. In an organic EL element, a strong electric field of 10 ⁵ V / cm or more is generally applied in the film thickness direction of an ultrathin film of 100 nm or less, whereas in the case of an organic TFT, a charge of several μm or more is applied. It is necessary to flow charges at a high speed with an electric field of a distance of 10 ⁵ V / cm or less, and the organic substance itself needs further conductivity. However, the above-described compound in the conventional organic TFT has a small field effect mobility, a slow response speed, and a problem in high-speed response as a transistor. Also, the on / off ratio was small.
The on / off ratio mentioned here means that the current flowing between the source and drain when the gate voltage is applied (on) is divided by the current flowing between the source and drain when the gate voltage is not applied (off). The on-current is a current value (saturation current) when the current flowing between the source and the drain is normally saturated while increasing the gate voltage.

As materials for organic TFTs, it has been reported that para-quaterphenyl (4Ph), para-kinkiphenyl (5Ph), para-sexiphenyl (6Ph), in which a plurality of benzene rings are bonded, are used as transistor materials (non-patent literature). 1, 2). However, there is a drawback that the mobility is low and the transistor characteristics are not exhibited unless the substrate is heated at the time of device fabrication.
Patent Document 1 discloses that when bisacetylenyl acetylene is used as a transistor material, high mobility is exhibited. However, naphthalene, anthracene and tetracene substituted with halogen atoms, which are used as raw materials for synthesizing the compounds shown in this document, have a disadvantage that they are more expensive than benzene substituted with halogen atoms.

US 7,109,519 B2 G. Horowitz et al., Synthetic Metals, 41-43, 1127, 1991 D. J. et al. Gundlach et al., Applied Physics Letter, 71, 3853, 1997.

  The present invention has been made to solve the above-mentioned problems, and since raw materials are readily available and can be synthesized by a general synthesis method, a compound for an organic thin film transistor having a low production cost, and An object of the present invention is to provide an organic thin film transistor having a high response speed (driving speed) when used as an organic semiconductor layer.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a compound for an organic thin film transistor represented by the following formula (1) that can be synthesized simply and inexpensively in the organic semiconductor layer of the organic thin film transistor. It has been found that the response speed (driving speed) can be increased by using it, and the present invention has been completed.

  That is, this invention is a compound for organic thin-film transistors which has a structure of following formula (1).

In the formula (1), X is represented by any of the three structures of the following formulas (2) to (4).

In the formula, Ar ₁ is an aromatic hydrocarbon group having 6 to 60 carbon atoms, an aromatic heterocyclic group having 1 to 60 carbon atoms, or a group having a structure in which two or more of these aromatic groups are linked, The group may have a substituent.
In the formula, R ^{1 to} R ⁵ 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 an alkyl group having 1 to 30 carbon atoms. A haloalkoxy group, 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 60 carbon atoms (the alkyl groups are bonded to each other) A ring structure containing a nitrogen atom may be formed), 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 3 to 3 carbon atoms 60 aromatic heterocyclic groups, groups having a structure in which two or more of these aromatic groups are linked; an alkylsilyl group having 3 to 20 carbon atoms, an alkylsilylacetylene group having 5 to 60 carbon atoms, or a cyano group Ri, each of these groups may have a substituent.
In the formula, R ^{6 to} R ¹⁵ 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 an alkyl group having 1 to 30 carbon atoms. A haloalkoxy group, 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 60 carbon atoms (the alkyl groups are bonded to each other) A ring structure including a nitrogen atom may be formed), 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 3 to 3 carbon atoms. An aromatic heterocyclic group having 60 carbon atoms, an alkylsilyl group having 3 to 20 carbon atoms which may have a substituent, an alkylsilylacetylene group having 5 to 60 carbon atoms, or a cyano group, and each of these groups has a substituent. And may be connected to each other between adjacent groups to form an aromatic hydrocarbon group having 6 to 60 carbon atoms, an aromatic heterocyclic group having 3 to 60 carbon atoms, or a saturated cyclic group having 6 to 60 carbon atoms. A structure may be formed. ]

  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 an organic current that controls a source-drain current by applying a voltage to the gate electrode. In the thin film transistor, the organic semiconductor layer provides an organic thin film transistor containing an organic compound having the structure of the formula (1).

  The present invention also provides an organic thin film light emitting transistor that emits light 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 compound according to the present invention can be synthesized at a low manufacturing cost because the raw materials are easily available and can be synthesized by a general synthesis method. When this compound is used as an organic semiconductor layer, an organic thin film transistor having a high response speed (driving speed) can be provided.

It is a figure which shows an example of the element structure of the organic thin-film transistor of this invention. It is a figure which shows an example of the element structure of the organic thin-film transistor of this invention. It is a figure which shows an example of the element structure of the organic thin-film transistor of this invention. It is a figure which shows an example of the element structure of the organic thin-film transistor of this invention. It is a figure which shows an example of the element structure of the organic thin-film transistor of this invention. It is a figure which shows an example of the element structure of the organic thin-film transistor of this invention. It is a figure which shows an example of the element structure of the organic thin-film transistor in the Example of this invention. It is a figure which shows the manufacturing process of the source electrode and drain electrode provided with the positive hole injection property electrode and the electron transport property electrode. It is a figure which shows the emission spectrum of the organic thin film light emitting transistor of this invention obtained in Example 6. FIG.

The compound for an organic thin film transistor of the present invention has a structure represented by the following formula (1).

In the formula (1), Ar ₁ is an aromatic hydrocarbon group having 6 to 60 carbon atoms, an aromatic heterocyclic group having 1 to 60 carbon atoms, or a structure in which two or more of these aromatic groups are connected, and these Each group may have a substituent.

In the formula (1), Ar ₁ is preferably a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms.

In Formula (1), Ar ₁ is preferably a substituted or unsubstituted aromatic heterocyclic group having 1 to 60 carbon atoms.

Specific examples of the aromatic hydrocarbon group for Ar ₁ include benzene, naphthalene, anthracene, tetracene, pentacene, phenanthrene, chrysene, triphenylene, corannulene, coronene, hexabenzotriphenylene, hexabenzocoronene, which may have a substituent. And residues such as sumanen.

Specific examples of the aromatic heterocyclic group for Ar ₁ include pyridine, pyrazine, quinoline, naphthyridine, quinoxaline, phenazine, diazaanthracene, pyridoquinoline, pyrimidoquinazoline, pyrazinoquinoxaline, phenanthroline, which may have a substituent. , Carbazole, dibenzothiophene, thienothiophene, dithienothiophene, dibenzofuran, benzodifuran, dithiaindacene, dithiaindenoindene, dibenzoselenophene, diselenindacene, diselenaindenoindene, dibenzosilole, [1] benzothieno [3 2-b] Residues such as benzothiophene.

The structure in which two or more aromatic groups of Ar ₁ are connected is a combination of the specific examples of the aromatic hydrocarbon group and aromatic heterocyclic group, and specific examples include biphenylene, terphenylene, and binaphthalene. , Bianthracene, phenylthiophene, thienylnaphthalene, thienylanthracene, phenylnaphthalene, phenylanthracene, pyridylnaphthalene, pyridylanthracene, bithiophene, terthiophene and the like.

In the formula (1), Ar ₁ may have a substituent, benzene, naphthalene, anthracene, tetracene, pentacene, phenanthrene, chrysene, pyridine, pyrazine, quinoline, naphthyridine, quinoxaline, phenazine, diazaanthracene, pyridoquinoline , Pyrimidoquinazoline, pyrazinoquinoxaline, phenanthroline, carbazole, dibenzothiophene, thienothiophene, dithienothiophene, [1] benzothieno [3,2-b] benzothiophene, biphenylene, terphenylene, binaphthalene, bianthracene, phenylthiophene, From thienylnaphthalene, thienylanthracene, phenylnaphthalene, phenylanthracene, pyridylnaphthalene, pyridylanthracene, bithiophene and terthiophene A group having a selected structure is preferred.

Examples of the substituent for Ar ₁ include an aromatic hydrocarbon group, an aromatic heterocyclic group, an alkyl group, an alkoxy group, an aryloxy group, an arylthio group, an alkoxycarbonyl group, an amino group, a halogen atom, a cyano group, a nitro group, A hydroxyl group, a carboxyl group, etc. are mentioned.

In the formula (1), X is represented by any of the structures of the following formulas (2) to (4).

In the formulas (2) to (4), R ^{1 to} R ⁵ 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, or an alkoxy group having 1 to 30 carbon atoms. , 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 60 carbon atoms ( 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; an aromatic carbon atom having 6 to 60 carbon atoms A hydrogen group, an aromatic heterocyclic group having 3 to 60 carbon atoms, a group having a structure in which two or more of these aromatic groups are linked; an alkylsilyl group having 3 to 20 carbon atoms, and an alkylsilylacetyl having 5 to 60 carbon atoms An emission group or a cyano group, each of these groups may have a substituent.

In the formula (1), R ^{6 to} R ¹⁵ 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 carbon number. 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 60 carbon atoms (the alkyl group is 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, an aromatic hydrocarbon group having 6 to 60 carbon atoms, An aromatic heterocyclic group having 3 to 60 carbon atoms, an alkylsilyl group having 3 to 20 carbon atoms, an alkylsilylacetylene group having 5 to 60 carbon atoms, or a cyano group, each of which has a substituent. Some well, also connected to each other with a group adjoining each other in the inside of R ⁶ to R ^15, an aromatic hydrocarbon group having 6 to 60 carbon atoms, an aromatic heterocyclic group having 3 to 60 carbon atoms, or carbon atoms 6 to 60 saturated cyclic structures may be formed.

In the formula (1), R ^{1 to} R ¹⁵ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 30 carbon atoms, an alkylsilylacetylene group having 5 to 60 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, or A cyano group is preferred.

In the formula (1), at least two adjacent groups in R ^{6 to} R ¹⁵ are connected to each other to form an aromatic hydrocarbon group having 6 to 60 carbon atoms or an aromatic complex having 3 to 60 carbon atoms. A ring group is preferably formed.

In addition, the organic thin film transistor compound of the present invention is basically bipolar showing p-type (hole conduction) and n-type (electron conduction), and can be used as a p-type element in combination with the source and drain electrodes described later. Can be driven as an n-type element, but in the formula (1), by using a group substituted on Ar ₁ or an electron-accepting group as R ^{1 to} R ¹⁵ , the lowest unoccupied orbital The (LUMO) level can be lowered to function as an n-type semiconductor.
Preferred as the electron-accepting group are a hydrogen atom, a halogen atom, a cyano group, a haloalkyl group having 1 to 30 carbon atoms, a haloalkoxy group having 1 to 30 carbon atoms, and a haloalkylsulfonyl group having 1 to 30 carbon atoms. In addition, by using an electron donating group as a group to be substituted on R ^{1 to} R ¹⁵ and Ar ₁ , the highest occupied orbital (HOMO) level can be increased to function as a p-type semiconductor. Preferred as the electron-donating group are a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an alkoxy group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, and a dialkylamino group having 2 to 60 carbon atoms. (The amino groups may be bonded to each other to form a ring structure containing a nitrogen atom).

Hereinafter, a specific example of the group represented by ^R 1 ^{to R 15} of formula (1).
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, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group N-octadecyl group, n-nonadecyl group, n-icosane group, n-henicosane group, n-docosan group, n-tricosane group, n-tetracosane group, n-pentacosane group, n-hexacosane group, n-heptacosane group , N-octacosane group, n-nonacosane group, n-triacontane 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, -Fluoromethyl group, 2-fluoromethyl 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. Examples of the ring structure include pyrrolidine and piperidine.
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 dithienophenyl group, a benzofuranyl group, a benzothiophenyl group, a quinolinyl group, a carbazolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, and a benzothiadiazonyl group.
The alkylsilyl group is a group represented by —SiX ¹ X ³ X ⁴ , and examples of X ¹ , X ³ and X ⁴ are the same as those described for the alkyl group.
The alkylsilylacetylene group is a group in which a group represented by the alkylsilyl group is interposed via an ethynylene group, and examples thereof include a trimethylsilylacetylene group, a triethylsilylacetylene group, and a triisopropylsilylacetylene group.

In R ^{1 to} R ⁵ , examples of the group having a structure in which two or more aromatic hydrocarbon groups having 6 to 60 carbon atoms and / or aromatic heterocyclic groups having 3 to 60 carbon atoms are connected include Ar ¹ described above. The same thing is mentioned.
As the aromatic hydrocarbon group or aromatic heterocyclic group formed by connecting adjacent groups among R ^{6 to} R ¹⁵ , the aromatic hydrocarbon group and aromatic heterocyclic group described above are explained. Examples similar to the above are given.

  Examples of the saturated cyclic structure include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a 1,4-dioxanyl group.

Examples of the substituent for R ^{1 to} R ¹⁵ include an aromatic hydrocarbon group, an aromatic heterocyclic group, an alkyl group, an alkoxy group, an aryloxy group, an arylthio group, an alkoxycarbonyl group, an amino group, a halogen atom, a cyano group, A nitro group, a hydroxyl group, a carboxyl group, etc. are mentioned.

  Hereinafter, although the specific example of the compound for organic thin-film transistors of this invention is given, this invention is not limited to these.

The compound for an organic thin film transistor of the present invention can be synthesized by a known method, for example, a coupling reaction using a transition metal catalyst represented by a Sonogashira coupling reaction as shown below.

  Note that an electronic device such as a transistor can have a high field-effect mobility and a high on / off ratio by using a material with high purity. Therefore, it is desirable to add purification by techniques such as column chromatography, recrystallization, distillation, sublimation, etc. as 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 as a final step of purification. By using these methods, it is preferable to use a material having a purity of 90% or more measured by HPLC, more preferably 95% or more, and particularly preferably 99% or more. In addition, the on / off ratio can be increased and the performance inherent to the material can be extracted.

Next, the element structure of the organic thin film transistor of the present invention will be described.
The element configuration of the organic thin film transistor of the present invention has at least three terminals of a gate electrode, a source electrode and a drain electrode, an insulator layer, and an organic semiconductor layer, and a source-drain current is controlled by applying a voltage to the gate electrode. Thin film transistor. And an organic-semiconductor layer contains the compound for organic thin-film transistors of this invention mentioned above, It is characterized by the above-mentioned. Usually, an organic thin film transistor is provided on a substrate.
The structure of the transistor is not particularly limited, and components other than the components of the organic semiconductor layer may have a known element configuration. A specific example of the element configuration of the organic thin film transistor will be described with reference to the drawings.

1-4 is a figure which shows an example of the element structure of the organic thin-film transistor of this invention.
The organic thin film transistor 1 of FIG. 1 has a source electrode 11 and a drain electrode 12 formed on a substrate 10 so as to face each other with a predetermined interval. And the organic-semiconductor layer 13 is formed so that the source electrode 11, the drain electrode 12, and the gap | interval between them may be covered, and the insulator layer 14 is laminated | stacked. A gate electrode 15 is formed on the insulator layer 14 and on the gap between the source electrode 11 and the drain electrode 12.

  The organic thin film transistor 2 in FIG. 2 has a gate electrode 15 and an insulator layer 14 in this order on a substrate 10, and a pair of source electrode 11 and drain formed on the insulator layer 14 with a predetermined interval therebetween. An electrode 12 is provided, and an organic semiconductor layer 13 is formed thereon.

  The organic thin film transistor 3 in FIG. 3 has a gate electrode 15, an insulator layer 14, and an organic semiconductor layer 13 in this order on a substrate 10. A pair of organic thin film transistors 3 formed at a predetermined interval on the organic semiconductor layer 13. A source electrode 11 and a drain electrode 12 are provided.

  The organic thin film transistor 4 of FIG. 4 has an organic semiconductor layer 13 on a substrate 10, and has a pair of source electrode 11 and drain electrode 12 formed on the organic semiconductor layer 13 with a predetermined interval. Further, the insulating layer 14 and the gate electrode 15 are provided in this order.

  The organic thin film transistor of the present invention has a field effect transistor (FET) structure. As described above, there are several configurations depending on the position of the electrodes, the layer stacking order, and the like. The organic thin film transistor is formed with an organic semiconductor layer (organic compound layer), a source electrode and a drain electrode formed so as 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.

Various configurations of the organic thin film transistor have been proposed, and the organic thin film transistor of the present invention is turned on / off, amplified, etc. by controlling the current flowing between the source electrode and the drain electrode by the voltage applied to the gate electrode. If it is a mechanism in which the effect of this is expressed, it is not limited to these element structures.
For example, the top-and-bottom contact organic thin-film transistor proposed by Yoshida et al. Of the National Institute of Advanced Industrial Science and Technology in the 49th Conference on Applied Physics Related Lectures 27a-M-3 (March 2002) (see FIG. 5) ), Or a vertical organic thin film transistor (see FIG. 6) proposed by Kudo et al. Of Chiba University in IEEJ Transactions 118-A (1998), page 1440.
Hereinafter, the constituent members of the organic thin film transistor will be described.

(Organic semiconductor layer)
The organic-semiconductor layer in the organic thin-film transistor of this invention contains the compound for organic thin-film transistors of this invention mentioned above. Although the film thickness of an organic-semiconductor layer is not specifically limited, 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 By the printing method, spin coating method, casting method, bar coating method, roll coating method, coating method and baking, electropolymerization, molecular beam deposition, self-assembly from solution, and a combination thereof, The organic semiconductor layer is made of the 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, one kind of material may be used for the organic semiconductor layer, and a plurality of thin films mixed with a plurality of materials or a plurality of different materials made of known semiconductors such as pentacene and thiophene oligomers may be used. These layers may be laminated.

(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 a gate electrode / substrate. Further, the surface of Si can be oxidized to form SiO ₂ and used as an insulating layer. In this case, a metal layer such as Au may be formed on the Si substrate serving as the substrate and gate electrode as an electrode for connecting the 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 / antimony, 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, sodium-potassium alloy, magnesium, lithium, aluminum Miniumu, magnesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, a lithium / aluminum mixture, or the like is used.

  Examples of the method for forming the electrode include 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, and ink jet. It 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.

  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 the present invention, a source electrode, a drain electrode, a gate electrode and a method for forming the source electrode are formed using a fluid electrode material containing the above conductive material, such as a solution, paste, ink, or dispersion. In particular, a fluid electrode material containing a conductive polymer or metal fine particles containing platinum, gold, silver, or copper is preferable. 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 and 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 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.

  These metal fine particle dispersions may be directly patterned by an ink jet method, or may be formed from a coating film by lithograph, laser ablation or the like. Moreover, the patterning method by printing methods, such as a letterpress, an intaglio, a lithographic plate, and screen printing, can also be used. After the electrode is formed and the solvent is dried, the metal fine particles are heat-fused by heating in a shape in the range of 100 ° C. to 300 ° C., preferably 150 ° C. to 200 ° C., if necessary. An electrode pattern having the following shape is formed.

  Furthermore, it is also preferable to use a known conductive polymer whose conductivity is improved by doping as a material for the gate electrode, the source electrode, and the drain electrode. For example, conductive polyaniline, conductive polypyrrole, conductive polythiophene (polyethylene diethylene Oxythiophene and polystyrene sulfonic acid complexes, etc.), polyethylene dioxythiophene (PEDOT) and polystyrene sulfonic acid complexes, and the like are also preferably used. These materials can reduce the contact resistance between the organic semiconductor layer of the source electrode and the drain electrode. These forming methods may also be patterned by an ink jet method, or may be formed from a coating film by lithography, laser ablation, or the like. Moreover, the patterning method by printing methods, such as a letterpress, an intaglio, a lithographic plate, and screen printing, can also be used.

In particular, the material for forming the source electrode and the drain electrode is preferably a material having a small electric resistance at the contact surface with the organic semiconductor layer among the examples described above. The electrical resistance at this time corresponds to the field-effect mobility when the current control device is manufactured, and it is necessary that the resistance be as small as possible in order to obtain a large mobility. This is generally determined by the magnitude relationship between the work function of the electrode material and the energy level of the organic semiconductor layer.
When the work function (W) of the electrode material is a, the ionization potential of the organic semiconductor layer is (Ip) b, and the electron affinity (Af) of the organic semiconductor layer is c, it is preferable that the following relational expression is satisfied. Here, a, b, and c are all positive values based on 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 organic semiconductor layer, a high-performance device can be obtained. In particular, it is preferable that the electrode material has a work function as large as possible, and the work function is 4.0 eV or more. The work function is preferably 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, 4.3) , 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 organic semiconductor 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 described in Chemistry Handbook Fundamentals, 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 of effective metals, 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), 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 (3.1eV), Yb (2.6eV), Zn (3.63eV), 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 the electrode material contains one or more of these low work function substances, 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.

In the organic thin film transistor of the present invention, for example, a buffer layer may be provided between the organic semiconductor layer and the source and drain electrodes for the purpose of improving the 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, Metal oxides other than alkali metals and alkaline earth metals such as Mn ₃ O ₄ , ZrO ₂ , WO ₃ , TiO ₂ , In ₂ O ₃ , ZnO, NiO, HfO ₂ , Ta ₂ O ₅ , ReO ₃ , 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.

  Although it is known that the buffer layer has the effect of lowering the threshold voltage by lowering the carrier injection barrier and driving the transistor at a low voltage, we have not only the low voltage effect on the compound of the present invention. It has been found that there is an effect of improving mobility. This is because a carrier trap exists at the interface between the organic semiconductor and the insulator layer, and when carrier injection occurs when a gate voltage is applied, the first injected carrier is used to fill the trap, but a buffer layer must be inserted. This is because the trap is buried at a low voltage and the mobility is improved. The buffer layer only needs to be thin between the electrode and the organic semiconductor layer, and the thickness is 0.1 nm to 30 nm, preferably 0.3 nm to 20 nm.

(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 it 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. Further, among the above materials, in particular, when an insulator layer is formed of silicon nitride such as Si ₃ N ₄ , SixNy, or SiONx (x, y> 0), a depletion layer is more easily generated, and the threshold of transistor operation is increased. The voltage can be further reduced.
As an insulator layer using an organic compound, polyimide, polyamide, polyester, polyacrylate, photo radical polymerization system, photo cation polymerization system photo-curable resin, copolymer containing acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, A novolac resin, cyanoethyl pullulan, or the like can also be used.

Others, wax, polyethylene, polychloropyrene, polyethylene terephthalate, polyoxymethylene, polyvinyl chloride, polyvinylidene fluoride, polymethyl methacrylate, polysulfone, polycarbonate, polyimide cyanoethyl pullulan, poly (vinylphenol) (PVP), poly (methyl methacrylate) (PMMA), polycarbonate (PC), polystyrene (PS), polyolefin, polyacrylamide, poly (acrylic acid), novolac resin, resole resin, polyimide, polyxylylene, epoxy resin, and polymers with high dielectric constant such as pullulan It is also possible to use materials.
As the organic compound material and polymer material used for the insulator layer, a material having water repellency is particularly preferable. By having water repellency, the interaction between the insulator layer and the organic semiconductor layer can be suppressed, and the crystallinity of the organic semiconductor layer can be improved by utilizing the cohesiveness inherent in the organic semiconductor, thereby improving the device performance. . Examples of this include Yasuda et al. Jpn. J. et al. Appl. Phys. Vol. 42 (2003) p. 6614-6618 and Janos Veres et al. Chem. Mater. , Vol. 16 (2004) p. The thing of 4543-4555 is mentioned.

  Further, when such a top gate structure as shown in FIGS. 1 and 4 is used, if such an organic compound is used as a material for the insulator layer, the organic semiconductor layer can be formed with less damage. Therefore, it is an effective method.

The 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 of these. 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 between the source and gate. Therefore, it is necessary to select an appropriate film thickness, which is usually 10 nm to 5 μm, preferably 50 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. Silane coupling agents such as hexamethyldisilazane, octadecyltrichlorosilane, trichloromethylsilazane, and self-organized alignment film materials such as alkane phosphoric acid, alkane sulfonic acid, and alkane carboxylic acid are insulated in a liquid phase or gas phase state. An example is a method in which the film is brought into contact with the surface of the film to form a self-assembled film, followed by appropriate drying treatment. 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.

The 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 source electrode is formed. It is preferable to form a series of device manufacturing steps up to the formation of the drain electrode without being exposed to the atmosphere at all, 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 this case, the surface of the insulating layer partially laminated with the source electrode and drain electrode) is cleaned and activated by ultraviolet irradiation, ultraviolet / ozone irradiation, oxygen plasma, argon plasma, etc., and then the organic semiconductor layer is stacked. Is preferred. Also, some p-type TFT materials are exposed to the atmosphere once, and the performance is improved by adsorbing oxygen or the like. Therefore, depending on the material, the materials are appropriately exposed to the atmosphere.
Furthermore, 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 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 can provide an organic thin film light emitting transistor that emits light by using a current flowing between a source electrode and a drain electrode and controls light emission by applying a voltage to a gate electrode. That is, an organic thin film transistor can be used as a light emitting element (organic EL). 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, it is necessary to inject holes from one of the source electrode and the drain electrode and electrons from the other, and the following conditions are preferably satisfied in order to improve the light emitting performance.

In the organic thin film light-emitting transistor of the present invention, it is preferable that at least one of the source electrode and the drain electrode is a hole injecting electrode in order to improve the hole injecting property. A hole injection electrode is an electrode containing a substance having a work function of 4.2 eV or higher. The upper limit of the work function of the hole injection electrode is 7.0 eV, for example.
In order to improve electron injectability, at least one of the source electrode and the drain electrode is preferably an electron injectable electrode. An electron injecting electrode is an electrode containing a substance having a work function of 4.3 eV or less. The lower limit of the work function of the electron injection electrode is, for example, 1.8 eV.
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.

In order to improve the hole injection property, it is preferable to insert a hole injection layer between at least one of the source electrode and the drain electrode and the organic semiconductor layer. Examples of the hole injection layer include amine-based materials used as a hole injection material and a hole transport material in an organic EL device.
In order to improve the electron injecting property, it is preferable to insert an electron injecting layer between at least one of the source electrode and the drain electrode and the organic semiconductor layer. The electron injection material used for the organic EL element can be used for the electron injection layer as well as the hole. More preferably, one of the electrodes is provided with a hole injection layer and the other electrode is provided with an electron injection layer. It is a thin film light emitting transistor.
[Example]

Next, the present invention will be described in more detail using examples.
Synthesis Example 1 (Synthesis of Compound (46))
Compound (46) was synthesized as follows. The synthesis route is shown below.
In a 300 ml three-necked flask, 3.00 g (8.87 mmol) of 4-bromo-p-terphenyl, 0.513 g (0.443 mmol) of tetrakistriphenylphosphine palladium, 0.169 g of copper (I) iodide (0 886 mmol) and replaced with argon. To this, 22 ml of triethylamine and 3.09 g (26.6 mmol) of 2-ethynylnaphthalene were added, and the mixture was heated to reflux for 9 hours under an argon atmosphere. The reaction solution was filtered, and the resulting solid was washed with dichloromethane and methanol to obtain 2.36 g (5.77 mmol, yield 65%) of compound (46).
It was confirmed to be the target product by measurement of 90 MHz ¹ H-NMR and FD-MS (field desorption mass analysis). The measurement results of FD-MS are shown below.
FD-MS, calcd for C ₄₈ H ₃₀ S ₂ = 378, found, m / z = 378 (M ⁺ , 100)
The compound was purified by sublimation at 260 ° C. The purity of compound (46) obtained by sublimation purification was 99.5%.
In addition, the apparatus and measurement conditions which were used for the measurement of FD-MS in the synthesis example 1 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)
The organic thin film transistor shown in FIG. 7 was produced by the following procedure. First, the glass substrate 10 was ultrasonically cleaned with a neutral detergent, pure water, acetone, and ethanol for 30 minutes each, and then a gold (Au) film having a thickness of 40 nm was formed by a sputtering method to produce a gate electrode 15. Next, this substrate 10 was set in a film forming section of a thermal CVD apparatus. On the other hand, 250 mg of polyparaxylene derivative [polyparaxylene chloride (Parylene)] (trade name; diX-C, manufactured by Daisan Kasei Co., Ltd.), which is a raw material for the insulating layer, was placed in a petri dish. The thermal CVD apparatus is evacuated with a vacuum pump and depressurized to 5 Pa. Then, the evaporation part is heated to 180 ° C. and the polymerization part is heated to 680 ° C. and left for 2 hours. Formed.
Next, the substrate is placed in a vacuum deposition apparatus (ULVAC, EX-400), and the compound (46) is formed on the insulator layer as an organic semiconductor layer 13 having a thickness of 50 nm at a deposition rate of 0.05 nm / s. Filmed. Next, gold was deposited to a thickness of 50 nm through a metal mask, so that the source electrode 11 and the drain electrode 12 that were not in contact with each other were formed with a spacing (channel length L) of 75 μm. At that time, an organic thin film transistor 3 was manufactured by forming a film so that the width (channel width W) of the source electrode and the drain electrode was 5 mm.

A gate voltage of −40 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 the drain. In this case, holes are induced in the channel region (between source and drain) of the organic semiconductor layer, and operate 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 3 × 10 ⁵ . Moreover, it was 6 * 10 ^<-2 > cm ^{< 2} > / Vs when the field effect mobility (micro | micron | mu) of a hole was computed from the following formula (A).
I _D = (W / 2L) · Cμ · (V _G −V _T ) ² (A)
Where _ID is the source-drain current, W is the channel width, L is the channel length, C is the capacitance per unit area of the gate insulator layer, V _T is the gate threshold voltage, and V _G is the gate voltage. .

Example 2 (Production of organic thin film transistor)
An organic thin film transistor was produced in the same manner as in Example 1 except that the compound (28) was used instead of the compound (46) as the material of the organic semiconductor layer. The obtained organic thin film transistor was p-type driven at a gate voltage V _{G of} −40 V in the same manner as in Example 1. Table 1 shows the results of measuring the on / off ratio of the current between the source and drain electrodes and calculating the field effect mobility μ of the holes.

Example 3 (Production of organic thin film transistor)
An organic thin film transistor was produced in the same manner as in Example 1 except that the compound (61) was used instead of the compound (46) as the material of the organic semiconductor layer. The obtained organic thin film transistor was p-type driven at a gate voltage V _{G of} −40 V in the same manner as in Example 1. Table 1 shows the results of measuring the on / off ratio of the current between the source and drain electrodes and calculating the field effect mobility μ of the holes.

Example 4 (Production of organic thin film transistor)
An organic thin film transistor was produced in the same manner as in Example 1 except that the compound (62) was used instead of the compound (46) as the material of the organic semiconductor layer. The obtained organic thin film transistor was p-type driven at a gate voltage V _{G of} −40 V in the same manner as in Example 1. Table 1 shows the results of measuring the on / off ratio of the current between the source and drain electrodes and calculating the field effect mobility μ of the holes.

Example 5 (Production of organic thin film transistor)
An organic thin film transistor was produced in the same manner as in Example 1 except that the compound (86) was used instead of the compound (46) as the material of the organic semiconductor layer. The obtained organic thin film transistor was p-type driven at a gate voltage V _{G of} −40 V in the same manner as in Example 1. Table 1 shows the results of measuring the on / off ratio of the current between the source and drain electrodes and calculating the field effect mobility μ of the holes.

Comparative Example 1 (Production of organic thin film transistor)
An organic thin film transistor was produced in the same manner as in Example 1 except that paracenylphenyl (Comparative Compound 1, hereinafter referred to as 6Ph) was used as the material for the organic semiconductor layer instead of Compound (46). The obtained organic thin film transistor was p-type driven at a gate voltage V _{G of} −40 V in the same manner as in Example 1. Table 1 shows the results of measuring the on / off ratio of the current between the source and drain electrodes and calculating the field effect mobility μ of the holes.

Comparative Example 2 (Production of organic thin film transistor)
An organic thin film transistor was produced in the same manner as in Example 1 except that bisanthracenylacetylene (represented by Comparative Compound 2, hereinafter referred to as BAA) was used as the material for the organic semiconductor layer instead of the compound (46). did. The obtained organic thin film transistor was p-type driven at a gate voltage V _{G of} −40 V in the same manner as in Example 1. Table 1 shows the results of measuring the on / off ratio of the current between the source and drain electrodes and calculating the field effect mobility μ of the holes.

Example 6 (Production of organic thin film light-emitting transistor)
An organic thin film light emitting transistor was produced by the following procedure. First, 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 as a gate 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 the compound (46) is deposited on the insulator layer (SiO ₂ ) at a deposition rate of 0.05 nm / s, and an organic semiconductor light-emitting layer with a thickness of 100 nm. Deposited as a layer.
Next, a source electrode and a drain electrode provided with a hole injecting electrode (Au) and an electron transporting electrode (Mg) were formed as shown in FIG.
Specifically, a metal mask 21 having a channel length of 75 μm and a channel width of 5 mm is installed in the same manner as described above, and the substrate 20 on which the organic semiconductor light emitting layer is formed is passed through the mask in a state where it is inclined 45 degrees with respect to the evaporation source. Gold 22 was deposited to a thickness of 50 nm (FIGS. 8 (1) and (2)). Next, Mg23 was deposited to a thickness of 100 nm with the substrate 20 tilted 45 degrees in the reverse direction (FIG. 8 (3)). As a result, an organic thin-film light-emitting transistor in which a source electrode and a drain electrode provided with a hole-injecting electrode 22 (Au) and an electron-transporting electrode 23 (Mg) were formed without being in contact with each other was manufactured (FIG. 8 ( 4)).
When -100 V was applied between the source and drain and -100 V was applied to the gate electrode, blue light emission of 40 cd / m ² was obtained. FIG. 9 shows an emission spectrum.

As described above in detail, the organic thin film transistor of the present invention has a high response speed (driving speed) and is turned on / off by using a compound having a specific structure having high electron mobility as a material of the organic semiconductor layer. The ratio is large and the performance as a transistor is high, and it can be used as an organic thin film light emitting transistor capable of emitting light.
The entire contents of the documents described in this specification are incorporated herein by reference.

Claims (11)

The compound for organic thin-film transistors which has a structure of following formula (1).
[Wherein, X is any group represented by the following formulas (2) to (4),
Ar ₁ is an aromatic hydrocarbon group having 6 to 60 carbon atoms, an aromatic heterocyclic group having 1 to 60 carbon atoms, or a group having a structure in which two or more of these aromatic groups are linked. It may have a substituent.
Wherein R ^{1 to} R ⁵ 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 1 to 30 carbon atoms. A haloalkoxy 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 60 carbon atoms (the alkyl groups are bonded to each other). 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; an aromatic hydrocarbon group having 6 to 60 carbon atoms, and 3 carbon atoms An aromatic heterocyclic group having ˜60, a group having a structure in which two or more of these aromatic groups are linked; an alkylsilyl group having 3 to 20 carbon atoms, an alkylsilylacetylene group having 5 to 60 carbon atoms, or a cyano group There, each of these groups may have a substituent.
R ^{6 to} R ¹⁵ 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, a dialkylamino group having 2 to 60 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 3 to 60 carbon atoms. Group heterocyclic group, alkyl silyl group having 3 to 20 carbon atoms, alkyl silyl acetylene group having 5 to 60 carbon atoms, or cyano group, each of these groups may have a substituent and are adjacent to each other. That are connected together in groups to each other, an aromatic hydrocarbon group having 6 to 60 carbon atoms, may form an aromatic heterocyclic group or a saturated cyclic structure having 6 to 60 carbon atoms of 3 to 60 carbon atoms. ]] 2. The compound for organic thin film transistor according to claim 1, wherein in the formula (1), Ar ₁ is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms. The compound for organic thin-film transistors according to claim 1, wherein Ar ₁ in the formula (1) is a substituted or unsubstituted aromatic heterocyclic group having 1 to 60 carbon atoms. In the formula (1), Ar ₁ is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 60 carbon atoms and / or a substituted or unsubstituted aromatic heterocyclic group having 1 to 60 carbon atoms. The compound for organic thin-film transistors according to claim 1, which has a structure linked as described above. In the formula (1), Ar ₁ is substituted or unsubstituted, benzene, naphthalene, anthracene, tetracene, pentacene, phenanthrene, chrysene, pyridine, pyrazine, quinoline, naphthyridine, quinoxaline, phenazine, diazaanthracene, pyridoquinoline, pyrimido Quinazoline, pyrazinoquinoxaline, phenanthroline, carbazole, dibenzothiophene, thienothiophene, dithienothiophene, [1] benzothieno [3,2-b] benzothiophene, biphenylene, terphenylene, binaphthalene, bianthracene, phenylthiophene, thienylnaphthalene, Select from thienylanthracene, phenylnaphthalene, phenylanthracene, pyridylnaphthalene, pyridylanthracene, bithiophene and terthiophene The compound for organic thin-film transistors according to claim 1, which is a group having a structure. In the formula (1), R ^{1 to} R ¹⁵ are each a hydrogen atom, a halogen atom, an alkyl group having 1 to 30 carbon atoms, an alkylsilylacetylene group having 5 to 60 carbon atoms, a haloalkyl group having 1 to 30 carbon atoms, or It is a cyano group, The compound for organic thin-film transistors in any one of Claims 1-5. In the formula (1), at least two adjacent groups in R ^{6 to} R ¹⁵ are connected to each other to form an aromatic hydrocarbon group having 6 to 60 carbon atoms or an aromatic complex having 3 to 60 carbon atoms. The compound for organic thin-film transistors in any one of Claims 1-5 which has formed the cyclic group.   In an organic thin film transistor having a gate electrode, three terminals of a source electrode and a drain electrode, an insulator layer, and an organic semiconductor layer, and controlling a source-drain current by applying a voltage to the gate electrode, the organic semiconductor layer comprises: The organic thin-film transistor containing the compound for organic thin-film transistors in any one of Claims 1-7.   The organic thin film transistor according to claim 8, wherein light emission is controlled by applying a voltage to the gate electrode by emitting light using a current flowing between the source electrode and the drain electrode.   10. The organic thin film transistor according to claim 9, wherein one of the source and drain electrodes is made of a material having a work function of 4.2 eV or more, and the other is made of a material having a work function of 4.3 eV or less.   The organic thin-film transistor according to claim 8, further comprising a buffer layer between the source and drain electrodes and the organic semiconductor layer.