JP2006339575A - Organic semiconductor film, organic thin film transistor and their fabrication process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor film produced by a simple process and exhibiting good characteristics as a transistor, and to provide an organic thin film transistor and its fabrication process. <P>SOLUTION: An organic semiconductor film containing the precursor of an aromatic polycyclic compound having a partial structure represented by general formula (1) (in the formula, X is a desorption group representing O or S, R<SB>1</SB>and R<SB>2</SB>represent hydrogen atom or substituent) is formed, and then the desorption group X is desorbed from the precursor thus obtaining an organic semiconductor film containing an aromatic polycyclic compound. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic semiconductor film, an organic thin film transistor, and a manufacturing method thereof.

  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 in paper media has been increasingly digitized. As a mobile display medium that is thin, light, and portable, electronic paper or digital paper can be used. The need for is increasing.

  In general, in a flat panel display device, a display medium is formed using elements utilizing liquid crystal, organic EL (organic electroluminescence), 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. Yes. As for the semiconductor portion that is the key to the switching operation, a plurality of types of semiconductor layers such as p-type and n-type are stacked. 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 formation of such a conventional TFT element using a Si material includes a process at a high temperature, the substrate material is restricted to 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. These compounds are not only charge transport materials for organic EL devices, but also organic laser oscillation devices such as those discussed in Science magazine 289, 599 (2000), and the like, for example, Nature (Nature). ) 403 volumes, 521 pages (2000), etc., application to organic thin film transistor elements (organic TFT elements) reported in many papers is expected. 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 by these low-temperature processes has been considered impossible for conventional Si-based semiconductor materials, but there is a possibility for devices using organic semiconductors, so 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.

  Examples of organic semiconductor materials for realizing such TFT elements include acenes such as pentacene and tetracene (see, for example, Patent Document 1), phthalocyanines including lead phthalocyanine, and low molecular compounds such as perylene and its tetracarboxylic acid derivatives (for example, Patent Document 2), aromatic oligomers typified by thiophene hexamers called α-thienyl or sexithiophene (see, for example, Patent Document 3), naphthalene, anthracene and 5-membered aromatic heterocycles are symmetrical. Condensed polymers such as condensed compounds (see, for example, Patent Document 4), mono-, oligo-, and polydithienopyridines (see, for example, Patent Document 5), and polythiophene, polythienylene vinylene, poly-p-phenylene vinylene (for example, non-patent documents) (See Patent Documents 1 to 3) To have. In particular, it has been reported that polyacene compounds such as pentacene and rubrene can provide high carrier mobility and excellent semiconductor device characteristics.

  However, aromatic polycyclic compounds such as polyacenes having a structure in which the benzene nucleus is condensed linearly can be used as a solvent if the number of rings is small, such as bicyclic naphthalene and tricyclic anthracene. Although it is soluble, acene-based compounds having four or more rings such as tetracene and pentacene have low solubility in solvents. However, from the viewpoint of characteristics as a semiconductor material, a polyacene compound having a large number of rings is preferable. Therefore, it is difficult to produce an organic semiconductor thin film having high organic TFT performance by a solution process.

  On the other hand, rubrene having a phenyl group introduced into tetracene exhibits very high mobility in a single crystal as introduced in Non-Patent Document 4, and is soluble in toluene and the like. However, the mobility of an organic semiconductor film manufactured by a solution process is not sufficient as compared with single crystal rubrene, and satisfactory TFT performance is not obtained.

As described above, vapor deposition or single crystal is not desirable because of low production efficiency and high cost. As a solution to the above problem, Patent Document 6 proposes a technique for forming an organic semiconductor film by converting a precursor, which substantially eliminates the need for a vacuum process. However, the mobility of the organic semiconductor film obtained by this method is not sufficient. Thus, at present, organic semiconductor materials that provide satisfactory performance in terms of compatibility between solution process suitability and carrier mobility are not sufficient, and further development of organic semiconductor materials is desired.
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A WO2004079834 Science 289, 599 pages (2000) “Nature” 403 volumes, 521 pages (2000) "Advanced Material", 2002, No. 2, page 99 Science Magazine, 303, 1644-1646 (2004)

  An object of the present invention is to provide an organic semiconductor film, an organic thin film transistor, and a method of manufacturing the same, which are manufactured by a simple process and have good characteristics as a transistor.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
After forming an organic semiconductor film containing a precursor of an aromatic polycyclic compound having a partial structure represented by the following general formula (1), the leaving group X is eliminated from the precursor to form an aromatic ring. An organic semiconductor film comprising the aromatic polycyclic compound formed by

(In the formula, X is a leaving group and represents O or S, and R ₁ and R ₂ represent a hydrogen atom or a substituent.)
(Claim 2)
The organic semiconductor film according to claim 1, wherein the aromatic polycyclic compound is a polyacene.

(Claim 3)
The organic semiconductor film according to claim 1 or 2, wherein the aromatic polycyclic compound has 4 to 20 rings.

(Claim 4)
4. The organic semiconductor film according to claim 1, wherein the means for removing the leaving group X is heating.

(Claim 5)
An organic thin film transistor using the organic semiconductor film according to claim 1 as an organic semiconductor layer.

(Claim 6)
A membrane from a solution or dispersion containing a precursor of an aromatic polycyclic compound having a partial structure represented by the general formula (1) and a solvent containing at least one solvent in which the precursor is soluble And a process for removing the leaving group X from the precursor in the film, converting it into an aromatic ring and converting it into an aromatic polycyclic compound.

(Claim 7)
The method for producing an organic semiconductor film according to claim 6, wherein the solution or dispersion contains a non-halogen solvent.

(Claim 8)
The method for producing an organic semiconductor film according to claim 6 or 7, wherein the means for converting into the aromatic polycyclic compound is heating.

(Claim 9)
9. A method for producing an organic thin film transistor, comprising forming an organic semiconductor layer by the method for producing an organic semiconductor film according to claim 7 or 8.

  According to the present invention, it is possible to provide an organic semiconductor film, an organic thin film transistor, and a method for manufacturing the same, which are manufactured by a simple process and have good characteristics as a transistor.

  As described above, aromatic polycyclic compounds represented by polyacenes are often poor in solution stability if they have low solubility or high solubility. In this invention, after forming an organic-semiconductor film on a board | substrate using the precursor of the aromatic polycyclic compound which has the partial structure represented by the said General formula (1) with high solubility or solution stability. It is characterized in that an aromatic polycyclic compound is formed by removing a leaving group with light or heat to form an aromatic ring. Gases such as oxygen are generated by desorption at the time of conversion, and can be easily removed from the formed coating film. Also, since the molecules are small, the structure of the coating film is not disturbed at the time of desorption. Sex film is obtained. For this reason, it is estimated that an organic semiconductor film having excellent characteristics as a transistor can be obtained.

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

[Aromatic polycyclic compound precursor having a partial structure represented by the general formula (1)]
The organic semiconductor material of the present invention is characterized in that an organic semiconductor film is formed on a substrate using a precursor of an aromatic polycyclic compound having a partial structure represented by the general formula (1).

  In the general formula (1), X is a leaving group and represents O or S.

In General formula (1), R < ₁ >, R < ₂ > represents a hydrogen atom or a substituent.

Examples of the substituent represented by R ₁ and R ₂ include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group). , Tetradecyl group, pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg ethynyl group, propargyl group etc.), aryl Group (for example, phenyl group, naphthyl group, etc.), aromatic heterocycle (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group) Group, phthalazinyl group, etc.), heterocyclic group (for example, pyrrolidyl group, Midazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (for example, Cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group) Etc.), a cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, Ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, Methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl 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, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group) 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, etc. Carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group) Group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenyl) Ureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butyls) Rufinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group) Cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc., arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group etc.), amino group (for example, amino group, ethylamino group, dimethyl) Amino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen Child (for example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, Examples thereof include a hydroxy group, a mercapto group, and a silyl group (for example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, a phenyldiethylsilyl group).

  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.

  Examples of the precursor of the aromatic polycyclic compound having a partial structure represented by the general formula (1) and the aromatic polycyclic compound obtained by conversion from the precursor include aromatic hydrocarbon condensed rings and And / or aromatic heterocyclic ring compounds.

  The aromatic hydrocarbon condensed ring in which the aromatic hydrocarbon ring is condensed includes polyacenes (polyacenes are compounds in which a plurality of benzene rings are condensed, such as naphthacene, anthracene, tetracene, pentacene, heptacene, hexacene, phenanthrene, dibenzo Pentacene, tetrabenzopentacene, pyrene, dibenzopyrene, chrysene, perylene, coronene, terylene, ovarene, quaterylene, circumanthracene, etc.), azulene ring, chrysene ring, naphthacene ring, acenaphthene ring, coronene ring, fluorene ring, full An olanthrene ring, a naphthacene ring, a perylene ring, a pentaphen ring, a picene ring, a pyrene ring, a pyranthrene ring, an anthraanthrene ring, and the like can be given.

  Preferably used are polyacenes such as anthracene, tetracene, pentacene, hexacene and phenanthrene.

  Aromatic hetero condensed rings condensed with aromatic hetero rings or condensed with aromatic hydrocarbon rings and aromatic hetero rings include benzimidazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline Ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, diazacarbazole ring (a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) and the like.

  The number of rings constituting the aromatic polycyclic compound is preferably 4-20.

  In addition, the aromatic hydrocarbon condensed ring or aromatic heterocyclic ring condensed with the above aromatic hydrocarbon ring and / or aromatic heterocyclic ring may be unsubstituted or may have a substituent. Examples of the group include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cyclo Alkyl groups (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl groups (for example, vinyl group, allyl group, etc.), alkynyl groups (for example, ethynyl group, propargyl group, etc.), aryl groups (for example, phenyl group, naphthyl group, etc.) ), Aromatic heterocycle (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group) Triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group) Propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.) Group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexyl group) Thio group etc.), arylthio group (eg phenylthio group, naphthylthio group etc.), alkoxycarbonyl group (eg methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group etc.) An aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), a sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexyl) Aminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl Group), 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 etc.), acyloxy group (eg acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group etc.), amide group (eg methylcarbonylamino) Group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylca Bonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), 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 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, naphthylsulfinyl group) , 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group) , Naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, Lopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (for example, fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (For example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, trimethyl group) Phenylsilyl group, phenyldiethylsilyl group, etc.).

  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.

  Hereinafter, although the specific example of the precursor of the aromatic polycyclic compound which has a partial structure represented by General formula (1) based on this invention is shown, this invention is not limited to these.

  Below, the synthesis example of these compounds is shown.

(Synthesis of Precursor 1)
Precursor 1 was synthesized according to the following scheme.

  In 100 ml of dichloromethane, 5 ml of water, 10 ml of 1-butanol, 1 g of rubrene (manufactured by Tokyo Chemical Industry Co., Ltd.) is dissolved, 0.3 g of disodium molybdate (VI) dihydrate, 5 ml of hydrogen peroxide, 0.3 g of sodium dodecyl sulfonate was added and stirred at room temperature for 2 hours. The obtained reaction mixture was washed with water and concentrated, and the target product was isolated by column chromatography. The isolated compound was confirmed to have the above structure by mass spectrometry. The yield of precursor 1 was 0.8 g, and the HPLC purity was 99.8%.

  Other compounds can be synthesized in the same manner.

[Conversion to an aromatic polycyclic compound obtained by removing the leaving group X from the precursor represented by the general formula (1) and cyclizing with aromatic ring]
In the present invention, an organic semiconductor film containing a precursor of an aromatic polycyclic compound having a partial structure represented by the general formula (1) is formed, and then the leaving group of the precursor is removed to remove the aromatic. It is characterized by cyclization and conversion to an aromatic polycyclic compound. Examples of the converted aromatic polycyclic compound are shown below.

  The compound n (n is an integer of 1 to 12) in this figure is obtained by converting the precursor n.

  In the conversion, the precursor leaving group contained in the coating film (organic semiconductor film) is eliminated by light irradiation and / or heating to form an aromatic ring, which is converted into an aromatic polycyclic compound. At this time, gas such as oxygen is generated, but it is easy to remove from the formed coating film, and since the molecules to be desorbed are small, the structure of the coating film is not disturbed at the time of desorption. Sex film is obtained.

  The heating condition depends on the type of the precursor, but is preferably about 50 to 250 ° C. for several minutes to 3 hours.

  The conversion to the compound represented by the general formula (1) is preferably performed in an inert gas such as nitrogen gas. In the present invention, the conversion means is preferably heating.

[Organic semiconductor film, organic thin film transistor]
The organic semiconductor film and organic thin film transistor of the present invention will be described.

  When the organic semiconductor material (precursor represented by the general formula (1)) according to the present invention is used for an organic semiconductor film and a semiconductor layer of an organic thin film transistor, an organic thin film transistor that can be driven satisfactorily can be provided. An organic thin film transistor has a top gate type having a source electrode and a drain electrode connected with an organic semiconductor as a semiconductor layer on a support, and having a gate electrode on the support via a gate insulating layer. It is roughly classified into a bottom gate type having a gate electrode and having a source electrode and a drain electrode connected by an organic semiconductor through a gate insulating layer.

  In order to install the organic semiconductor material according to the present invention in an organic semiconductor film or a semiconductor layer of an organic thin film transistor, it can be installed on a substrate by vacuum deposition, but it is dissolved in an appropriate solvent and an additive is added as necessary. The prepared solution is preferably placed on the substrate by cast coating, spin coating, printing, inkjet method, ablation method or the like.

  In this case, the solvent for dissolving the organic semiconductor material according to the present invention is not particularly limited as long as it can dissolve the organic semiconductor material to prepare an appropriate concentration solution or can be dispersed. Is a chain ether solvent such as diethyl ether or diisopropyl ether, a cyclic ether solvent such as tetrahydrofuran or dioxane, a ketone solvent such as acetone or methyl ethyl ketone, an alkyl halide solvent such as chloroform or 1,2-dichloroethane, toluene, Aromatic solvents such as o-dichlorobenzene, nitrobenzene and m-cresol, N-methylpyrrolidone, aliphatic hydrocarbon solvents such as carbon disulfide and hexane, cycloaliphatic hydrocarbon solvents such as cyclohexane, etc. Can do. Of these solvents, a solvent containing a non-halogen solvent is preferable, and a non-halogen solvent is preferable.

  In the organic thin film transistor of the present invention, the organic semiconductor material according to the present invention is preferably used for the semiconductor layer as described above. The semiconductor layer is preferably formed by applying a solution or dispersion containing these organic semiconductor materials. The solvent for dissolving the organic semiconductor material is preferably a solvent containing the non-halogen solvent, and is preferably composed of a non-halogen solvent.

  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, magnesium / Copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, lithium / aluminum mixture, etc., especially platinum, gold, silver, copper, aluminum, indium, ITO And carbon are preferred. Alternatively, a known conductive polymer whose conductivity is improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylenedioxythiophene and polystyrenesulfonic acid, or the like is 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 from a conductive thin film formed using a method such as vapor deposition or sputtering using the above as a raw material, or 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, laser ablation, or the like. 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 a relief printing plate, an intaglio printing plate, a planographic printing plate or a screen printing method 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 trioxide yttrium. 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 the like, spraying Examples include a wet process such as a coating method, a spin coating method, a blade coating method, a dip coating method, a casting method, a roll coating method, a bar coating method, a coating method such as a die coating method, and a patterning method such as printing or inkjet. 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 an organic compound film, polyimide, polyamide, polyester, polyacrylate, photo-curing polymer of photo radical polymerization system, photo cation polymerization system, or copolymer containing acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolac resin, and Cyanoethyl pullulan or the like can also 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 organic thin-film transistor using the organic-semiconductor film formed using the organic-semiconductor material based on this invention is demonstrated.

  FIG. 1 is a diagram showing a configuration example of an organic thin film transistor of 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, and an organic semiconductor layer 1 made of the organic semiconductor material according to the present invention is formed between both electrodes. An organic thin film transistor is formed by forming an insulating layer 5 on the substrate and further forming a gate electrode 4 thereon. 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 according to 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 thin film transistor sheet.

  The organic thin film transistor sheet 10 has a large number of organic thin film transistors 11 arranged in a matrix. 7 is a gate bus line of each organic thin film transistor 11, and 8 is a source bus line of each organic thin film transistor 11. An output element 12 is connected to the source electrode of each organic thin film transistor 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.

Example 1
A 200 nm thick thermal oxide film was formed on a Si wafer having a specific resistance of 0.02 Ω · cm as a gate electrode to form a gate insulating layer, and then surface treatment with octadecyltrichlorosilane was performed.

A solution in which the precursor 1 was dissolved in a THF / cyclohexane mixed solvent (ratio 2: 8) was bubbled with nitrogen gas to remove dissolved oxygen in the solution, under a nitrogen gas atmosphere of 1.013 × 10 ² kPa. The surface of the thermal oxide film (silicon oxide film) was applied using an applicator and dried at room temperature. At this time, the film thickness of the semiconductor layer was 20 nm. When heat treatment was performed at 200 ° C. for 20 minutes in a nitrogen gas atmosphere, a thin film of Compound 1 converted from the precursor 1 was formed.

  Gold was deposited on the surface of the film using a mask to form a source electrode and a drain electrode. Thus, an organic thin film transistor 1 (the present invention) having a channel length L = 30 μm and a channel width W = 1 mm was produced.

The organic thin film transistor 1 operated well as a p-channel enhancement type TFT. About the obtained organic thin-film transistor, it was 0.33 cm < ² > / V * s when the carrier mobility was calculated | required from the saturation area | region of the IV characteristic.

Example 2
An organic thin film transistor 2 (the present invention) was produced in the same manner as in the production of the organic thin film transistor 1 of Example 1, except that the precursor 1 was replaced with the precursor 2. The organic thin film transistor 2 operated well as a p-channel enhancement type TFT. About the obtained organic thin-film transistor, it was 0.24 cm < ² > / V * s when the carrier mobility was calculated | required from the saturation area | region of the IV characteristic.

Example 3
A chloroform solution of rubrene (manufactured by Tokyo Chemical Industry Co., Ltd.) was applied using an applicator and dried at room temperature. At this time, the film thickness of the semiconductor layer was 20 nm. Thereafter, heat treatment was not performed, and an organic thin film transistor 3 (Comparative Example 1) was produced in the same manner as the organic thin film transistor 1 of Example 1. About the obtained organic thin-film transistor, it was 0.09 cm < ² > / V * s when the carrier mobility was calculated | required from the saturation area | region of the IV characteristic.

It is a figure which shows the structural example of the organic thin-film transistor of this invention. It is an example of the schematic equivalent circuit schematic of the organic thin-film transistor sheet 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 thin-film transistor sheet 11 Organic thin-film transistor 12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit

Claims (9)

After forming an organic semiconductor film containing a precursor of an aromatic polycyclic compound having a partial structure represented by the following general formula (1), the leaving group X is eliminated from the precursor to form an aromatic ring. An organic semiconductor film comprising the aromatic polycyclic compound formed by

(In the formula, X is a leaving group and represents O or S, and R ₁ and R ₂ represent a hydrogen atom or a substituent.) The organic semiconductor film according to claim 1, wherein the aromatic polycyclic compound is a polyacene. The organic semiconductor film according to claim 1 or 2, wherein the aromatic polycyclic compound has 4 to 20 rings. 4. The organic semiconductor film according to claim 1, wherein the means for removing the leaving group X is heating. An organic thin film transistor using the organic semiconductor film according to claim 1 as an organic semiconductor layer. A membrane from a solution or dispersion containing a precursor of an aromatic polycyclic compound having a partial structure represented by the general formula (1) and a solvent containing at least one solvent in which the precursor is soluble And a process for removing the leaving group X from the precursor in the film, converting it into an aromatic ring and converting it into an aromatic polycyclic compound. The method for producing an organic semiconductor film according to claim 6, wherein the solution or dispersion contains a non-halogen solvent. The method for producing an organic semiconductor film according to claim 6 or 7, wherein the means for converting into the aromatic polycyclic compound is heating. 9. A method for producing an organic thin film transistor, comprising forming an organic semiconductor layer by the method for producing an organic semiconductor film according to claim 7 or 8.

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