JP2006140180A - Organic thin film transistor material, organic thin film transistor, field effect transistor, and switching element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic TFT in which the molecular design of a useful organic TFT material is performed and which has good ON/OFF characteristics and high durability, and to provide a switching element in which switching characteristics are good using them. <P>SOLUTION: The organic thin film transistor material contains a compound represented by a general formula (1) or (2) äin the formula, A is an oxygen atom, a sulfur atom, a selenium atom, =N(R<SB>1</SB>) group, or =CR<SB>2</SB>R<SB>3</SB>group, R<SB>1</SB>, R<SB>2</SB>, and R<SB>3</SB>are each a hydrogen atom or a substituent. Z is a hydrocarbon ring which may form a condensed ring}, and the compound represented by the general formula (1) or (2) has at least three unsaturated bonds which can cross conjugated in a molecule. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic thin film transistor material, an organic thin film transistor, a field effect transistor, and a switching element.

  With the widespread use of information terminals, there is an increasing need for flat panel displays as computer displays. In addition, with the progress of computerization, information that has been provided on paper media in the past has become more and more electronically provided. As a mobile display medium that is thin, light, and easy to carry, electronic paper or There is a growing need for digital paper.

  In general, in a flat display device, a display medium is formed using an element utilizing liquid crystal, organic EL, electrophoresis, or the like. In such display media, a technique using an active drive element (TFT element) as an image drive element has become mainstream in order to ensure uniformity of screen brightness, screen rewrite speed, and the like. For example, in a normal computer display, these TFT elements are formed on a glass substrate, and liquid crystal, organic EL elements, etc. are sealed.

  Here, semiconductors such as a-Si (amorphous silicon) and p-Si (polysilicon) can be mainly used for the TFT element, and these Si semiconductors (and metal films as necessary) are formed into a multilayer structure. The TFT element is manufactured by sequentially forming the drain and gate electrodes on the substrate. The manufacture of such a TFT element usually requires sputtering or other vacuum manufacturing processes.

  However, in the manufacture of such a TFT element, the vacuum system manufacturing process including the vacuum chamber must be repeated many times to form each layer, and the apparatus cost and running cost have become enormous. For example, in a TFT element, it is usually necessary to repeat processes such as vacuum deposition, dope, photolithography, development, etc. many times to form each layer, and the element is formed on a substrate through tens of steps. ing. A plurality of types of semiconductor layers, such as p-type and n-type, are also stacked on the semiconductor portion that is the key to the switching operation. In such a conventional manufacturing method using a Si semiconductor, it is not easy to change the equipment, for example, a design change of a manufacturing apparatus such as a vacuum chamber is required in response to the need for a large display screen.

  In addition, since the conventional TFT element using the Si material includes a process at a high temperature, the substrate material must be a material that can withstand the process temperature.

  Therefore, in practice, glass must be used, and when the above-described thin display such as electronic paper or digital paper is configured using such a conventionally known TFT element, the display is heavy and flexible. Products that may break due to chipping or dropping impact. These characteristics resulting from the formation of TFT elements on a glass substrate are undesirable in satisfying the need for an easy-to-carry-type thin display accompanying the progress of computerization.

  On the other hand, in recent years, organic semiconductor materials have been energetically studied as organic compounds having high charge transport properties. In addition to charge transport materials for organic EL devices, these compounds are expected to be applied to organic laser oscillation devices (for example, Non-Patent Document 1) and organic thin film transistors reported in many papers. (For example, Non-Patent Document 2 etc.).

  If these organic semiconductor devices can be realized, there is a possibility of obtaining a semiconductor that can be made into a solution by simplifying the manufacturing process by vacuum or low-pressure deposition at a relatively low temperature and further improving the molecular structure appropriately. It is conceivable that the organic semiconductor solution is made into an ink and manufactured by a printing method including an ink jet method. Manufacturing using these low-temperature processes has been considered impossible for conventional Si-based semiconductor materials, but there are possibilities for devices using organic semiconductors, and therefore the above-mentioned restrictions on substrate heat resistance are relaxed. For example, a TFT element may be formed on the transparent resin substrate. If a TFT element is formed on a transparent resin substrate and the display material can be driven by the TFT element, the display is lighter and more flexible than conventional ones, and will not crack even if dropped (or very difficult to break) It could be a display.

  However, organic semiconductors for realizing such TFT elements have been studied so far as acenes such as pentacene and tetracene (for example, see Patent Document 1), phthalocyanines including lead phthalocyanine, perylene and its tetra. Low molecular weight compounds such as carboxylic acid derivatives (for example, see Patent Document 2), aromatic oligomers typically represented by thiophene hexamers called α-thienyl or sexithiophene (for example, see Patent Document 3), naphthalene, Compounds in which a 5-membered heteroaromatic ring is condensed symmetrically on anthracene (for example, see Patent Document 4), mono, oligo and polydithienopyridines (for example, see Patent Document 5), polythiophene, polythienylene vinylene, poly -Conjugated polymers such as p-phenylene vinylene Etc. limited number of compounds (e.g., see Non-Patent Documents 1 to 3.) Have only in the development of the semiconductor composition using the novel charge-transporting material showing high carrier mobility has been awaited.

  If a solution coating such as an inkjet method can be applied instead of forming a pentacene derivative-containing layer, which has been reported to have good TFT characteristics as a conventionally known organic semiconductor material, through a vapor deposition step, a great cost advantage in manufacturing can be expected. However, it has been pointed out that the coating solution has insufficient stability, such as insufficient solubility in various organic solvents, and crystallization and precipitation are likely to occur after solution preparation.

  In view of this, techniques relating to organic TFT materials using pentacene derivatives into which substituents are introduced have been disclosed for the purpose of improving solubility and coating solution stability (see, for example, Patent Documents 9 and 10).

  However, when an alkyl group or the like is introduced, it is difficult to obtain sufficient solubility, operability such as temperature control during coating is difficult, and it is difficult to produce a uniform coating film.

  In addition, in Japanese Patent Application Laid-Open No. 2003-292588, US Patent Application Publication Nos. 2003/136958, 2003/160230, and 2003/164495, “integrated circuit logic element for microelectronics and polymer TFT When is used, its mechanical durability is greatly improved and its usable life is extended.

  However, many of the semiconductor polythiophenes are oxidatively doped with ambient oxygen, which increases the conductivity and is not considered stable when exposed to air. As a result, the off-state current of devices made from these materials is increased, thus reducing the current on / off ratio. Therefore, many of these materials must be taken with utmost care to eliminate or minimize oxidative doping by eliminating environmental oxygen during material processing and device fabrication. This precautionary measure increases manufacturing costs, and the attractiveness of certain polymer TFTs as an economic alternative to amorphous silicon technology, especially for large area devices, is diminished. These and other disadvantages are avoided or minimized in embodiments of the present invention.

Therefore, an electronic device having a strong resistance against oxygen and a relatively high current on / off ratio is desired ", and various solutions have been proposed (for example, patents). (Refs. 6, 7 and 8)), but the level of improvement is not satisfactory and further improvements are desired.
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A JP 2003-261655 A JP 2003-264327 A JP 2003-268083 A International Publication No. 03/016599 Pamphlet US Patent Application Publication No. 2003/0105365 “Science” 289, 599 (2000) “Nature” 403, 521 (2000) Advanced Material, 2002, No. 2, page 99

  An object of the present invention is to design an organic TFT material that is useful for the production of an organic thin film transistor (hereinafter abbreviated as an organic TFT), and the organic TFT produced using the organic TFT material has a high carrier mobility and a gate. It was found that while having excellent transistor characteristics such as the ratio between the maximum current value and the minimum current value when the voltage is changed, that is, the ON / OFF characteristics are good, the transistor has high durability. Moreover, it is providing the switching element with favorable switching characteristics using them.

  The above object of the present invention has been achieved by the following configurations 1 to 7.

(Claim 1)
The compound represented by the following general formula (1) or (2), and the compound represented by the general formula (1) or (2) is capable of cross-conjugation in the molecule, is at least three An organic thin film transistor material characterized by having a saturated bond.

[In the formula, A represents an oxygen atom, a sulfur atom, a selenium atom, a = N (R ₁ ) group or a = CR ₂ R ₃ group, and R ₁ , R ₂ and R ₃ are each a hydrogen atom or a substituted group. Represents a group. Z represents a hydrocarbon ring that may form a condensed ring. ]
(Claim 2)
The organic thin-film transistor material according to claim 1, wherein the hydrocarbon ring includes a 6-membered ring.

(Claim 3)
3. The organic thin film transistor material according to claim 1, comprising at least one selected from the group consisting of compounds represented by the following general formulas (3) to (5) based on a hydrocarbon ring.

[Wherein, A ¹ and A ² each represent an oxygen atom, a sulfur atom, a selenium atom, a ═N (R ₁ ) group, or a ═CR ₂ R ₃ group, wherein R ₁ , R ₂ , R ₃ are Each represents a hydrogen atom or a substituent. n represents an integer of 1 to 4. ]
(Claim 4)
4. The organic thin film transistor material according to claim 3, wherein n in each of the general formulas (3) to (5) is 3 or 4.

(Claim 5)
The organic thin-film transistor material of any one of Claims 1-4 is used for a channel layer, The organic thin-film transistor characterized by the above-mentioned.

(Claim 6)
An organic charge transporting material and a gate electrode directly or indirectly in contact with the organic charge transporting material, and by applying a voltage between the gate electrode and the organic charge transporting material, the organic charge transporting property In a field effect transistor that controls the current in a material,
5. The field effect transistor according to claim 1, wherein the organic charge transporting material is the organic thin film transistor material according to claim 1.

(Claim 7)
A switching element comprising the organic thin film transistor according to claim 5 or the field effect transistor according to claim 6.

  According to the present invention, an organic TFT material useful for producing an organic thin film transistor (hereinafter abbreviated as an organic TFT) is molecularly designed, and the carrier mobility is high (especially good even after aging) using the organic TFT material. The ratio between the maximum current value and the minimum current value when the gate voltage is changed, that is, the ON / OFF characteristics are good (especially good even after aging) and the like, while exhibiting excellent transistor characteristics and high durability. In addition, an organic TFT having the above characteristics was provided, and further, by using them, a switching element having good switching characteristics could be provided.

  In the organic TFT material of the present invention, an organic TFT material useful for thin film transistor applications can be obtained by using the structure defined in any one of claims 1 to 6. Further, the organic TFT and field effect transistor of the present invention produced using the organic TFT material have high carrier mobility, and the ratio between the maximum current value and the minimum current value when the gate voltage is changed, that is, ON / It was found that the transistor had excellent durability while exhibiting excellent transistor characteristics, such as good OFF characteristics. Moreover, it turned out that the switching element produced using this organic TFT or this field effect transistor shows a favorable switching characteristic.

  Hereinafter, details of each component according to the present invention will be sequentially described.

  The present inventors have studied various problems as organic EL materials of so-called acene derivatives such as conventionally known pentacene derivatives, and as a result of molecular design, the results are represented by the above general formula (1) or (2). By using a compound or at least one compound selected from the group consisting of the above general formulas (3) to (5), a conventionally known acene derivative in which a simple alkyl group or the like has been introduced can be obtained. The present inventors have succeeded in imparting sufficient solubility to the organic EL device material, and have greatly improved operability such as temperature control during coating.

  At the same time, at the time of forming the organic semiconductor layer of the organic TFT element, succeeded in forming a coating film that maintains the ideal molecular arrangement as found in the conventionally known pentacene, As a result, the TFT performance was greatly improved.

<< Organic thin film transistor materials >>
The organic thin film transistor material of the present invention will be described.

  As the organic thin film transistor material of the present invention, at least one compound selected from the compound represented by the above general formula (1) or (2) and the compound group consisting of the above general formulas (3) to (5) is used. .

<< Compounds Represented by General Formulas (1) and (2) >>
In the general formulas (1) and (2), the compound represented by the general formula (1) or (2) has at least three unsaturated bonds capable of cross-conjugation in the molecule, and Z is a condensed group. The hydrocarbon ring which may form a ring is represented. Moreover, it is preferable that the said hydrocarbon ring forms a quinoid structure with A represented by General formula (1) mentioned later. Examples of the quinoid structure include a quinone structure, a quinoneimine structure, a quinonediimine structure, a quinomethane structure, and a quinodimethane structure.

  Here, cross-conjugation means that there are three unsaturated systems α, β, and γ in one molecule, and α and β, and β and γ can be conjugated respectively, but α and γ are conjugated. Indicates a case where it cannot be done.

  Specifically, as a molecule having a cross conjugation, 3-methylene-1.4-pentadiene, acrylic acid and the like are compounds well known to those skilled in the art.

  Further, as the matrix of the hydrocarbon ring, a ring forming an acene derivative is preferably used as the matrix, for example, a benzene ring, a naphthalene ring, an anthracene ring, a tetracene ring, a heptacene ring, a hexacene ring, an octacene ring, a pentaphen ring. , Hexaphen rings and the like, and preferably used are anthracene ring, tetracene ring, pentacene ring, heptacene ring, hexacene ring and the like.

  However, the unsaturated bond in the ring of the hydrocarbon ring is set so that at least three unsaturated systems form a cross-conjugated system.

  For example, in Exemplified Compound (6) described in Synthesis Example (1) to be described later, Exemplified Compound (6) is obtained using a synthetic raw material having an anthracene ring as the base of the hydrocarbon ring. Has a quinodimethane structure (a kind of quinoid structure), and the quinodimethane structure has a structure in which the unsaturated bond in the anthracene ring has a cross-conjugated system.

  Similarly, in Exemplified Compound (36) described in Synthesis Example (2) described later, Exemplified Compound (36) is obtained using a synthetic raw material having a pentacene ring as a base of a hydrocarbon ring. 36) has a quinodimethane structure, and the quinodimethane structure has a structure in which the unsaturated bond in the pentacene ring is arranged to have a cross-conjugated system.

  The step of setting a cross conjugated system in the constituent ring of the acene derivative that is the base of the hydrocarbon ring will be described later in the synthesis example of the compound represented by the general formula (1) or (2). Thus, in the synthesis process, a synthesis route that provides a cross-conjugated system is appropriately selected.

Further, the hydrocarbon ring is described below general formula (1), (2) may further have a substituent represented by R ₁ in = N (R ₁₎ a group represented by A .

In the general formulas (1) and (2), the substituent represented by R ₁ of the ═N (R ₁ ) group represented by A is an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group). Group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl) Group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), aromatic heterocyclic group (eg, pyridyl group, pyrimidinyl group, furyl group, Pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4-toluene) Azol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, benzofuryl Group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring is replaced by a nitrogen atom), Quinoxalinyl group, pyridazinyl group, triazinyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy) Group, pentyloxy group, hex Siloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxyl group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group) Group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.) , Alkoxycarbonyl groups (for example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl (Eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octyl) Aminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group) Octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group Group), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, Ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino Group), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentyl) Aminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (eg methyl Ureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group) Butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthyls Finyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenyl) Sulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino) Group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl) , Pentafluorophenyl group, etc.), a cyano group, a nitro group, hydroxy group, a mercapto group, a silyl group (e.g., trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, a phenyl diethyl silyl group and the like), and the like.

  These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

In the general formulas (1) and (2), the substituent represented by R ₂ and R ₃ of the ═CR ₂ R ₃ group represented by A has the same definition as the substituent represented by R ₁ .

<< Compound represented by general formula (3), (4) or (5) based on hydrocarbon ring >>
The compound based on the hydrocarbon ring represented by the general formula (3), (4) or (5) according to the present invention will be described.

In each of the general formulas (3), (4), and (5), the ═N (R ₁ ) group represented by A ¹ and A ² is represented by A in the general formulas (1) and (2). ═N (R ₁ ) group.

In each of the general formulas (3), (4) and (5), the ═CR ₂ R ₃ groups represented by A ¹ and A ² are each represented by A in the general formulas (1) and (2). R = synonymous with CR ₂ R ₃ group.

  Specific examples of the compound represented by the general formula (1) or (2) and the compound represented by the general formula (3), (4) or (5) according to the present invention are shown below. The invention is not limited to these.

  As an example of the synthesis of the compound represented by the general formula (1) or (2) and the compound represented by the general formula (3), (4) or (5) according to the present invention, the compound (6) Examples of synthesis of each of the compounds (3 &) are shown below, but the present invention is not limited thereto. Moreover, as a synthesis method, it can synthesize | combine with reference to the synthesis method well-known to the said expert.

  << Synthesis Example 1: Synthesis of Compound (6) >>

  Tetrakis (triphenylphosphine) palladium (0) 0.1 g and sodium hydride 0.75 g were added to a 200 ml three-necked flask, and the system was purged with nitrogen. Further, 60 ml of tetrahydrofuran was added, and 20 ml of a tetrahydrofuran solution of 1.2 g of malonitrile was added dropwise with stirring, and stirring was continued for 1 hour at room temperature. Thereafter, 20 ml of a tetrahydrofuran solution containing 2.0 g of the compound (6-1) was added dropwise, and the mixture was heated to reflux for 20 hours after completion of the addition. After completion of the reaction, diatomaceous earth filtration was performed at room temperature, and the filtrate was washed with saturated brine, dried over magnesium sulfate, and then concentrated under reduced pressure using a rotary evaporator. The residue was purified by column chromatography to obtain 1.1 g of white solid of compound (6-2).

The structure of the obtained compound (6-2) was identified using ¹ H-NMR (nuclear magnetic resonance spectrum) and mass spectrum.

  Next, 1.1 g of the compound (6-2) obtained above and 80 ml of acetonitrile were added to a 200 ml three-necked flask, and 1.2 g of 2,3-dichloro-5,6-dicyanobenzoquinone was added in a small amount at 5 ° C. or lower. Added in increments. After completion of the addition, the mixture was stirred at room temperature for 3 hours, and after completion of the reaction, the mixture was concentrated under reduced pressure using a rotary evaporator. The residue was purified by column chromatography to obtain 0.7 g of the target compound (6) as a white solid.

The structure of the compound (6) was identified using ¹ H-NMR (nuclear magnetic resonance spectrum) and mass spectrum.

  << Synthesis Example 2: Synthesis of Compound (36) >>

  In Synthesis Example 1 described above, Compound (36-1) (a compound described in US Patent Application Publication No. 2003/105365) was used instead of Compound (6-1) (Compound of Synthesis Example 1 (6) The compound (36-2) was synthesized in the same manner except that the number of moles was adjusted to be the same as the number of moles of -1), and then the obtained compound (36-2) was used for the purpose. Compound (36) was obtained.

The structures of the compound (36-2) and the target compound (36) were identified using ¹ H-NMR (nuclear magnetic resonance spectrum) and mass spectrum.

<< Organic TFT, field effect transistor and switching element >>
The organic TFT, the field effect transistor and the switching element using them according to the present invention will be described. Here, the switching element is sometimes referred to as an organic TFT element depending on its usage, and is sometimes referred to as a field effect transistor element.

  The organic TFT material of the present invention can be used for a channel layer of an organic TFT or a field effect transistor, thereby providing a switching element (also referred to as a transistor device) that is driven satisfactorily. An organic TFT (organic thin film transistor) has a source electrode and a drain electrode connected by an organic semiconductor channel as a channel on a support, a top gate type having a gate electrode on a gate insulating layer thereon, and a support First, it is roughly classified into a bottom gate type having a gate electrode on a body and having a source electrode and a drain electrode connected by an organic semiconductor channel through a gate insulating layer.

  In order to install the organic thin film transistor material according to the present invention in a channel (also referred to as a channel layer) of a switching element using an organic TFT or a field effect transistor, it can be installed on a substrate by vacuum deposition, but an appropriate solvent is used. It is preferable that a solution prepared by dissolving and adding an additive as necessary is placed on a substrate by cast coating, spin coating, printing, an ink jet method, an ablation method or the like.

  In this case, the solvent for dissolving the organic TFT material of the present invention is not particularly limited as long as the organic TFT material can be dissolved to prepare a solution having an appropriate concentration. Specifically, diethyl ether or diisopropyl is used. Chain ether solvents such as ether, cyclic ether solvents such as tetrahydrofuran and dioxane, ketone solvents such as acetone and methyl ethyl ketone, alkyl halide solvents such as chloroform and 1,2-dichloroethane, toluene, o-dichlorobenzene, Aromatic solvents such as nitrobenzene and m-cresol, N-methylpyrrolidone, carbon disulfide and the like can be mentioned.

  In the present invention, the material for forming the source electrode, the drain electrode and the gate 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, magnesi A copper / gold mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide mixture, a lithium / aluminum mixture, etc., in particular, platinum, gold, silver, copper, aluminum, indium, ITO and carbon are preferred. Alternatively, known conductive polymers whose conductivity is improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylenedioxythiophene and polystyrenesulfonic acid, and the like are also preferably used. Among them, those having low electrical resistance at the contact surface with the semiconductor layer are preferable.

  As a method for forming an electrode, a method for forming an electrode using a known photolithographic method or a lift-off method, using a conductive thin film formed by a method such as vapor deposition or sputtering using the above as a raw material, a metal foil such as aluminum or copper There is a method of etching using a resist by thermal transfer, ink jet or the like. Alternatively, a conductive polymer solution or dispersion, or a conductive fine particle dispersion may be directly patterned by ink jetting, or may be formed from a coating film by lithography or laser ablation. Furthermore, a method of patterning an ink containing a conductive polymer or conductive fine particles, a conductive paste, or the like by a printing method such as relief printing, intaglio printing, planographic printing, or screen printing can also be used.

  Various insulating films can be used as the gate insulating layer, 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, Examples thereof include barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, and yttrium trioxide. Of these, silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide are preferable. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.

  Examples of the method for forming the film include a vacuum process, 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, an atmospheric pressure plasma method, and a spray process. Wet processes such as coating methods, spin coating methods, blade coating methods, dip coating methods, casting methods, roll coating methods, bar coating methods, die coating methods, and other wet processes such as printing and ink jet patterning methods, etc. Can be used depending on the material.

  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. Among these, the atmospheric pressure plasma method and the sol-gel method are preferable.

  The method for forming an insulating film by plasma film formation under atmospheric pressure is a process in which a reactive gas is discharged under atmospheric pressure or a pressure near atmospheric pressure to excite reactive gas to form a thin film on a substrate. The method is described in JP-A-11-61406, JP-A-11-133205, JP-A-2000-121804, JP-A-2000-147209, JP-A-2000-185362 (hereinafter referred to as atmospheric pressure). Also called plasma method). Accordingly, a highly functional thin film can be formed with high productivity.

  In addition, as the organic compound film, polyimide, polyamide, polyester, polyacrylate, photo radical polymerization type, photo cation polymerization type photo curable resin, or a copolymer containing an acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolac resin, Also, cyanoethyl pullulan or the like can be used. As the method for forming the organic compound film, the wet process is preferable. An inorganic oxide film and an organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.

  Moreover, a support body is comprised with glass or a flexible resin-made sheet | seat, for example, a plastic film can be used as a sheet | seat. Examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC). And a film made of cellulose triacetate (TAC), cellulose acetate propionate (CAP), or the like. Thus, by using a plastic film, the weight can be reduced as compared with the case of using a glass substrate, the portability can be improved, and the resistance to impact can be improved.

  Below, the field effect transistor using the organic thin film formed using the organic TFT material of this invention is demonstrated.

  FIG. 1 is a diagram showing a configuration example of an organic TFT according to the present invention. In FIG. 2A, a source electrode 2 and a drain electrode 3 are formed on a support 6 by a metal foil or the like, an organic semiconductor layer 1 made of the organic semiconductor material of the present invention is formed between the two electrodes, and a substrate is formed thereon. An insulating layer 5 is formed, and a gate electrode 4 is further formed thereon to form a field effect transistor. FIG. 2B shows the organic semiconductor layer 1 formed between the electrodes in FIG. 1A so as to cover the entire surface of the electrode and the support using a coating method or the like. (C) shows that the organic semiconductor layer 1 is first formed on the support 6 by using a coating method or the like, and then the source electrode 2, the drain electrode 3, the insulating layer 5, and the gate electrode 4 are formed.

  In FIG. 4D, after forming the gate electrode 4 on the support 6 with a metal foil or the like, the insulating layer 5 is formed, and the source electrode 2 and the drain electrode 3 are formed on the metal foil or the like on the insulating layer 5. An organic semiconductor layer 1 made of the organic semiconductor material of the present invention is formed between the electrodes. In addition, the configuration as shown in FIGS.

  FIG. 2 is a diagram showing an example of a schematic equivalent circuit diagram of an organic TFT sheet.

  The organic TFT sheet 10 has a large number of organic TFTs 11 arranged in a matrix. 7 is a gate bus line of each TFT 11, and 8 is a source bus line of each TFT 11. An output element 12 is connected to the source electrode of each TFT 11, and this output 12 is, for example, a liquid crystal, an electrophoretic element or the like, and constitutes a pixel in the display device. The pixel electrode may be used as an input electrode of the photosensor. In the illustrated example, a liquid crystal as an output element is shown by an equivalent circuit composed of a resistor and a capacitor. 13 is a storage capacitor, 14 is a vertical drive circuit, and 15 is a horizontal drive circuit.

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

Example 1
<< Preparation of Organic Thin Film Transistor (Organic TFT) Element 1 >>: Comparison After forming a 2000 mm thick thermal oxide film on a Si wafer having a resistivity of 0.01 Ω · cm as a gate electrode to form a gate insulating layer, octadecyltri Surface treatment with chlorosilane was performed. A chloroform solution of the comparative compound (1) (poly (3-hexylthiophene) (regioregular, Aldrich, average molecular weight 89000, PHT)) was applied using an applicator and dried naturally to give a cast film (thickness 50 nm) And was heat-treated at 50 ° C. for 30 minutes in a nitrogen atmosphere. Further, gold was deposited on the surface of this film using a mask to form a source electrode and a drain electrode. An organic thin film transistor element 1 having a source electrode and a drain electrode each having a width of 100 μm, a thickness of 200 nm, a channel width W = 3 mm, and a channel length L = 20 μm was produced.

<< Preparation of Organic TFT Elements 2 and 3 >>: Comparison In preparation of the organic TFT element 1, the comparative compound (1) was used as the comparative compound (2) (pentacene, a commercially available reagent manufactured by Aldrich) (3) Organic thin-film transistor elements 2 and 3 were produced in the same manner except that (the compound described in International Publication No. 03/016599 pamphlet) was used.

<< Preparation of Organic TFT Elements 4-13 >>: Present Invention Organic TFT transistor elements 4-13 were prepared in the same manner as in the preparation of organic TFT element 1, except that the compound (1) was changed to the compounds shown in Table 1. did.

<< Evaluation of Organic TFT Elements 1 to 13 >>: Carrier mobility, ON / OFF ratio Organic thin film transistor elements 1 to 13 produced as described above showed good operating characteristics of p-channel enhancement type FETs. Further, for the organic thin film transistor elements 4 to 9, the carrier mobility is obtained from the saturation region of the IV characteristic, and the drain current value when the gate bias is set to −50V and 0V with the drain / bias ratio set to −50V. Ratio).

  The obtained element was left in the atmosphere for one month, and the carrier mobility and the ON / OFF ratio were obtained again. The results are shown in Table 1.

  From Table 1, it was found that the organic thin film transistor element of the present invention had better characteristics as a transistor and further suppressed deterioration over time as compared with comparison.

It is a figure which shows the structural example of the organic TFT which concerns on this invention. It is an example of the schematic equivalent circuit schematic of the organic TFT of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic-semiconductor layer 2 Source electrode 3 Drain electrode 4 Gate electrode 5 Insulating layer 6 Support body 7 Gate bus line 8 Source bus line 10 Organic TFT sheet 11 Organic TFT
12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit

Claims (7)

The compound represented by the following general formula (1) or (2), and the compound represented by the general formula (1) or (2) is capable of cross-conjugation in the molecule, is at least three An organic thin film transistor material characterized by having a saturated bond.

[In the formula, A represents an oxygen atom, a sulfur atom, a selenium atom, a = N (R ₁ ) group or a = CR ₂ R ₃ group, and R ₁ , R ₂ and R ₃ are each a hydrogen atom or a substituted group. Represents a group. Z represents a hydrocarbon ring that may form a condensed ring. ] The organic thin-film transistor material according to claim 1, wherein the hydrocarbon ring includes a 6-membered ring. 3. The organic thin film transistor material according to claim 1, comprising at least one selected from the group consisting of compounds represented by the following general formulas (3) to (5) based on a hydrocarbon ring.

[Wherein, A ¹ and A ² each represent an oxygen atom, a sulfur atom, a selenium atom, a ═N (R ₁ ) group, or a ═CR ₂ R ₃ group, wherein R ₁ , R ₂ , R ₃ are Each represents a hydrogen atom or a substituent. n represents an integer of 1 to 4. ] 4. The organic thin film transistor material according to claim 3, wherein n in each of the general formulas (3) to (5) is 3 or 4. The organic thin-film transistor material of any one of Claims 1-4 is used for a channel layer, The organic thin-film transistor characterized by the above-mentioned. An organic charge transporting material and a gate electrode directly or indirectly in contact with the organic charge transporting material, and by applying a voltage between the gate electrode and the organic charge transporting material, the organic charge transporting property In a field effect transistor that controls the current in a material,
5. The field effect transistor according to claim 1, wherein the organic charge transporting material is the organic thin film transistor material according to claim 1. A switching element comprising the organic thin film transistor according to claim 5 or the field effect transistor according to claim 6.

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