JP2007208032A - Organic semiconductor material, organic semiconductor film, method of manufacturing organic semiconductor film, organic semiconductor device and organic thin-film transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic semiconductor film which exhibits high carrier mobility, has high ON/OFF ratio and also has high durability (oxidation stability and improvement of secular change stability) by molecule-designing an organic semiconductor material useful for the purpose of a thin-film transistor and using the obtained organic semiconductor material, and to provide a method of manufacturing this organic semiconductor film, an organic semiconductor device having this organic semiconductor film, and an organic thin-film transistor. <P>SOLUTION: The organic semiconductor material contains a compound having at least one biphenylene ring in a molecule. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  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 elements, but also organic laser oscillation elements (for example, see Non-Patent Document 1) and organic thin film transistor elements (also referred to as organic TFT elements) reported in many papers. ) Is expected (see, for example, Non-Patent Document 2).

  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.

  However, organic semiconductors for realizing such TFT elements have been studied so far such as acenes such as pentacene and tetracene (see, for example, Patent Document 1), phthalocyanines including lead phthalocyanine, perylene and its tetra. Low molecular weight compounds such as carboxylic acid derivatives (see, for example, 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 5-membered aromatic heterocycles are condensed symmetrically on anthracene (for example, see Patent Document 4), mono-, oligo- and polydithienopyridines (for example, see Patent Document 5), polythiophene, polythienylene vinylene Conjugated high such as poly-p-phenylene vinylene A material that exhibits a sufficient carrier mobility / ON / OFF ratio while maintaining sufficient solubility in a solvent is not limited to a limited number of compounds (eg, non-patent documents 1 to 3). Not found.

  Recently, a very high mobility has been reported by a single crystal of rubrene, which is a highly soluble acene (see, for example, Non-Patent Document 4), but a rubrene film formed by solution casting is like this. A single crystal structure is not taken and sufficient mobility is not obtained.

  Further, pentacene, which has been reported to exhibit high carrier mobility and excellent semiconductor device characteristics, has a problem that it is insoluble or hardly soluble in organic solvents. In order to improve this point, a compound having a functional group added to pentacene is also disclosed, and it has been reported that relatively good carrier mobility can be obtained by solution coating (for example, see Patent Document 6). .

  However, these acene-based compounds such as rubrene and pentacene are easily oxidized by air and are converted into oxidants and dimers such as endoperoxide, and the performance as a field effect transistor is greatly deteriorated. It is known that there are still problems to be solved regarding the storage stability in solution and the stability of the coating film.

  Examples of acene-based compounds that are relatively stable against oxidation include some compounds in which 6- and 13-positions of pentacene and 5- and 11-positions of anthradithiophene are substituted with silylethynyl groups. There are reports that it is good (see, for example, Non-Patent Documents 5, 6, 7 and Patent Document 7).

  However, these reports only describe the qualitative properties that the stability against oxidation has been improved, and the stability to the extent that it can withstand practical use has not yet been obtained.

Therefore, a novel charge transporting material that dissolves at high concentration in a solvent having process suitability, has sufficient carrier mobility, on / off ratio, and stability in a solution state. Development of the used semiconducting composition is awaited.

  However, in the above-mentioned document, the compound is not studied as a semiconductor material, and only usage is exemplified, and sufficient TFT performance is not obtained.

Therefore, a novel charge transporting material that dissolves in a high concentration in a solvent having process suitability, has sufficient carrier mobility, on / off ratio, and stability in a solution state is used. Development of a semiconducting composition that has been long-awaited is highly desired.
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A International Publication No. 03/016599 Pamphlet US Pat. No. 6690029 Specification “Science” 289, 599 (2000) “Nature” 403, 521 (2000) Advanced Material, 2002, No. 2, page 99 Science, 2004, 303, 5664, 1644-1646. Org. Lett. , Vol. 4 (2002), 15 pages J. et al. Am. Chem. Soc. , Vol. 127 (2005), 4986 pages Adv. Mater. , Vol. 15 (2003), 2009

  The object of the present invention is to molecularly design an organic semiconductor material useful for thin film transistor applications, use the obtained organic semiconductor material, exhibit high carrier mobility, a high ON / OFF ratio, and high durability (oxidation). It is to provide an organic semiconductor film having both stability and stability with time), a method for producing the organic semiconductor film, an organic semiconductor device having the organic semiconductor film, and an organic thin film transistor.

  The above object of the present invention has been achieved by the following configurations 1 to 12.

  1. An organic semiconductor material comprising a compound containing at least one biphenylene ring as a partial structure in a molecule.

  2. 2. The organic semiconductor according to 1, wherein the compound includes an aromatic condensed ring in which four or more rings are condensed as a partial structure, and the aromatic condensed ring includes at least one biphenylene ring as a partial structure. material.

  3. 2. The organic compound according to 1 above, wherein the compound includes an aromatic condensed ring in which five or more rings are condensed as a partial structure, and the aromatic condensed ring includes at least two biphenylene rings as the partial structure. Semiconductor material.

  4). 4. The organic semiconductor material according to any one of 1 to 3, wherein the compound has a partial structure represented by the following general formula (1).

[Wherein, R _1, R ₂ each represents a hydrogen atom, a halogen atom or a substituent, n1, n2 represents an integer of 0 to 3. ]
5). 5. The organic semiconductor material as described in 4 above, wherein R _{1 in the} general formula (1) is a group represented by the following general formula (a).

Formula (a)
-C≡C-R
[Wherein, R represents a substituent. ]
6). 5. The organic semiconductor material as described in 4 above, wherein R ₁ and R _{2 in} the general formula (1) are each a group represented by the general formula (a).

7). R in the general formula (a) is an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, or —Si (R ′) ₃ (where R ′ is The organic semiconductor material according to 5 or 6, wherein the organic semiconductor material represents a substituent.

  8). The organic-semiconductor film of any one of said 1-7 is contained, The organic-semiconductor film characterized by the above-mentioned.

  9. 8. An organic semiconductor formed by dissolving or dispersing the organic semiconductor material according to any one of 1 to 7 in an organic solvent, and applying and drying the obtained solution or dispersion. film.

  10. 8. An organic semiconductor device using the organic semiconductor material according to any one of 1 to 7 above.

  11. 8. An organic thin film transistor, wherein the organic semiconductor material according to any one of 1 to 7 is used for a semiconductor layer.

  12 8. A method for producing an organic semiconductor film, comprising: dissolving or dispersing the organic semiconductor material according to any one of 1 to 7 in an organic solvent, and applying and drying the obtained solution or dispersion. .

  According to the present invention, organic semiconductor materials useful for thin film transistor applications are molecularly designed, and the resulting organic semiconductor materials exhibit high carrier mobility, a high ON / OFF ratio, and high durability (oxidation stability). And an organic semiconductor device and an organic thin film transistor having the organic semiconductor film can be provided. Moreover, the manufacturing method of this organic-semiconductor film was able to be obtained.

  In the organic semiconductor material of the present invention, an organic semiconductor material useful for thin film transistor applications was obtained by using the configuration defined in any one of claims 1 to 7.

  Using the obtained organic semiconductor material, an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor (also referred to as an organic TFT) exhibiting high carrier mobility and good ON / Off characteristics were obtained. Moreover, the manufacturing method of this organic-semiconductor film was able to be obtained.

  Moreover, it turned out that the organic electroluminescent element which comprised the organic thin-film transistor (organic TFT) of this invention shows a favorable light emission characteristic.

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

《Organic semiconductor material》
The organic semiconductor material according to the present invention will be described.

  As a result of various studies on the above problems by the present inventors, a compound having at least one biphenylene ring in its molecule as a partial structure has high durability (oxidation stability and stability over time), and carrier. It was found useful as an organic semiconductor material with high mobility.

  Moreover, an organic semiconductor film, an organic semiconductor device having the organic semiconductor film, and an organic semiconductor transistor could be obtained using the organic semiconductor material.

<Compound containing at least one biphenylene ring as a partial structure>
Examples of the compound containing at least one biphenylene ring as a partial structure according to the present invention include compounds described in the following (a) and (b).

(A) a compound containing an aromatic condensed ring in which four or more rings are condensed as a partial structure, and the aromatic condensed ring containing at least one biphenylene ring as a partial structure;
(B) a compound including an aromatic condensed ring in which five or more rings are condensed as a partial structure, and the aromatic condensed ring including at least two biphenylene rings as a partial structure. Particularly preferably used are compounds having a partial structure represented by the general formula (1).

<< Compound having a partial structure represented by the general formula (1) >>
The compound which has the partial structure represented by General formula (1) based on the organic-semiconductor material of this invention is demonstrated.

  Here, the partial structure represented by the general formula (1) will be described in detail.

In the general formula (1), examples of the halogen atom represented by R ₁ and R ₂ include a fluorine atom, a chlorine atom, and a bromine atom.

In the general formula (1), R ₁ and R ₂ each represent a substituent represented by an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, a 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, 1-propenyl group, 2- Butenyl group, 1,3-butadienyl group, 2-pentenyl group, isopropenyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), aromatic hydrocarbon group (aromatic carbocyclic group, aryl group, etc.) For example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group Azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group, etc., aromatic heterocyclic group (eg, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group) A group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, a quinazolinyl group, a carbazolyl group, a carbolinyl group, a diazacarbazolyl group (in which one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom) ), 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.), alkylthio group (eg, methylthio group, ethylthio group, Propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (for example, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (for example, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group ( For example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (for example, phenyloxycarbonyl) Nyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecyl) Aminosulfonyl 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, 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, cyclohexyl Silaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethyl) Ureido 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, naphthylsulfinyl group, 2-pyridylsulfuric group ), Alkylsulfonyl groups (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl groups or heteroarylsulfonyl groups (for example, Phenylsulfonyl 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.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group Group, hydroxy group, a mercapto group, -Si (R ') ₃ (wherein, R' halogen is a substituent group, the substituent in the general formula (1), represented by each of R _1, R ₂ It is synonymous with an atom and a substituent, for example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, a phenyldiethylsilyl group, etc. are mentioned. ), A phosphono group, 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.

Among the above, in the general formula (1), the substituents represented by R ₁ and R ₂ are each preferably a group represented by the general formula (a). In the general formula (1), , R ₁ and R ₂ are particularly preferably both groups represented by the general formula (a).

(Group represented by general formula (a))
The group represented by the general formula (a) according to the present invention will be described.

In the group represented by the general formula (a), the substituent represented by R has the same meaning as the halogen atom and substituent represented by R ₁ and R ₂ in the general formula (1). Are preferably used as an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, or —Si (R ′) ₃ (wherein R ′ represents a substituent.

  The organic semiconductor material containing a compound containing at least one biphenylene ring as a partial structure in the molecule according to the present invention forms a film with higher crystallinity (organic semiconductor film), and as a result, the mobility of the coating film Not only can be made high, but also a thin film into which deterioration factors such as oxygen and moisture are difficult to penetrate, and durability (oxidation stability and stability over time) can be improved.

  Regarding oxidative stability, it has been found that the introduction of an electronically attractive ethynyl group improves resistance to oxidation. When introduced, a higher effect was obtained.

  In addition, as described above, molecules having high planarity such as pentacene and sexithiophene are often insoluble, but the compound having the partial structure represented by the general formula (1) is an aromatic condensed ring. When the group represented by the general formula (a) was introduced on the benzene ring constituting the compound, the solubility in a solvent was greatly improved.

  In addition, since the group represented by the general formula (a) includes a triple bond, the carbon atom connected to the aromatic condensed ring does not have a hydrogen atom, and there is no group that prevents the π plane from approaching the molecule. Inter-π stack is promoted more. Furthermore, by introducing a reasonably large substituent such as a silyl group at the end of the ethynyl group, it has become possible to adopt a “face-to-face” structure in which the overlap between π planes is large and advantageous for carrier movement. .

  From the above, the organic semiconductor material of the present invention containing a compound containing at least one biphenylene as a partial structure in the molecule and containing the partial structure represented by the general formula (1) as a component It has been found that the material has high durability (oxidation stability and stability over time) and high carrier mobility as compared with conventional organic semiconductor materials.

  The organic semiconductor material of the present invention contains a compound containing at least one biphenylene ring as a partial structure in the molecule. Here, the compound is included as a main component of the organic semiconductor material of the present invention. It is a feature. Here, the main component means that 50% by mass or more of the total mass of the organic semiconductor material is contained. Of course, the said compound may be contained in content of 100 mass% in the organic-semiconductor material of this invention.

  Hereinafter, although the specific example of the compound which contains at least one biphenylene ring as a partial structure in a molecule | numerator based on the organic-semiconductor material of this invention is shown, this invention is not limited to these.

  The compound containing at least one biphenylene ring as a partial structure in the molecule according to the organic semiconductor material of the present invention can be synthesized by referring to a conventionally known synthesis method. Here, specific examples are given above. A synthesis example of the exemplified compound 1 is shown as an example.

<< Synthesis of Compound 6 >>
The outline of the synthesis scheme of Compound 6 is shown below.

  The synthesis of compound 6 is first described in J. Am. Chem. Soc. Chem. Commun. , 1983, vol. Intermediate 1 was synthesized with reference to pages 9,502, and Am. Chem. Soc. 2001, vol. Compound Example 6 was synthesized with reference to pages 123, 9482.

<Organic semiconductor film>
The organic semiconductor film according to the present invention will be described.

  The organic semiconductor material of the present invention can be mixed with an appropriate organic solvent (described later) and used as a solution or dispersion.

  When producing an organic semiconductor film using a solution containing the organic semiconductor material of the present invention, any organic solvent may be used, or two or more organic solvents may be mixed and used. Preferably, it contains at least one non-halogen solvent, and more preferably only non-halogen solvent.

<< Solution or dispersion at room temperature >>
The organic semiconductor film of the present invention is preferably produced through a step of forming a film using a solution or a dispersion at room temperature, prepared by mixing the organic semiconductor material of the present invention with the organic solvent shown below. Here, the solution or dispersion at room temperature refers to an organic semiconductor material and an organic solvent at 10 ° C to 80 ° C.
When mixed under the condition of ° C., it is preferable that a solution or a dispersion is formed. The dispersion represents a state in which the organic semiconductor material is dispersed in the form of particles. A partially dissolved state is also included.

  Further, as one embodiment of the dispersion, for example, it dissolves under a temperature condition of 80 ° C. to form a solution, but when returned to room temperature (usually showing a temperature of about 25 ° C.), particles or aggregates of organic semiconductor material And a state in which precipitates are dispersed in an organic solvent.

(Organic solvent)
There is no restriction | limiting in particular as an organic solvent used for preparation of said solution or dispersion liquid, Although a single solvent or a mixed solvent may be sufficient, Preferably, a non-halogen-type solvent is used. Non-halogen solvents used in the present invention include aliphatic solvents such as hexane and octane, alicyclic solvents such as cyclohexane, aromatic solvents such as benzene, toluene and xylene, tetrahydrofuran, dioxane, and ethylene glycol diethyl ether. , Ether solvents such as anisole, benzyl ethyl ether, ethyl phenyl ether, diphenyl ether, and methyl-t-butyl ether, ester solvents such as methyl acetate, ethyl acetate, and ethyl cellosolve, alcohol solvents such as methanol, ethanol, and isopropanol, acetone , Ketone solvents such as methyl ethyl ketone, cyclohexanone, 2-hexanone, 2-heptanone and 3-heptanone, other dimethylformamide, dimethylsulfoxide, diethylformamide, 1,3- Oxolane, and the like.

  Further, the organic solvent used in combination is not particularly limited, but preferred examples include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, pyrrolidone, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, Examples include methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, methyl β-methoxypropionate, ethyl β-ethoxypropionate, propylene glycol monomethyl ether acetate, toluene, xylene, hexane, limonene, cyclohexane, etc. It is done. Two or more of these organic solvents can be used in combination.

  Further, as the ester solvent, oxyisobutyric acid alkyl ester or the like may be used, and as oxyisobutyric acid ester, α-methoxyisobutyrate methyl, α-methoxyisobutyrate ethyl, α-ethoxyisobutyrate methyl, α-ethoxyisobutyrate ethyl, etc. α-alkoxyisobutyric acid alkyl esters; β-alkoxyisobutyric acid alkyl esters such as methyl β-methoxyisobutyrate, ethyl β-methoxyisobutyrate, methyl β-ethoxyisobutyrate, ethyl β-ethoxyisobutyrate; and methyl α-hydroxyisobutyrate, α Α-hydroxyisobutyric acid alkyl esters such as ethyl-hydroxyisobutyrate, and in particular, methyl α-methoxyisobutyrate, methyl β-methoxyisobutyrate, methyl β-ethoxyisobutyrate or methyl α-hydroxyisobutyrate may be used. it can.

<< Organic semiconductor device, organic thin film transistor (also called organic TFT) >>
The organic semiconductor device and organic thin film transistor (also referred to as organic TFT in the present application) of the present invention will be described.

  The organic semiconductor material of the present invention can be used for a semiconductor layer such as an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor (organic TFT), thereby providing an organic semiconductor device and an organic TFT that are driven well.

An organic TFT (organic thin film transistor) has a source electrode and a drain electrode connected by an organic semiconductor channel as a semiconductor layer on a support, and a top gate type having a gate electrode via a gate insulating layer thereon, A bottom gate type having a gate electrode on a support and having a source electrode and a drain electrode connected by an organic semiconductor channel through a gate insulating layer is roughly classified.

  In order to install the organic semiconductor material of the present invention on the semiconductor layer of the organic TFT, it can be installed on the substrate by vacuum deposition, but a solution prepared by dissolving in an appropriate solvent and adding additives as necessary is cast. It is preferable to install on the substrate by coating, spin coating, printing, ink jet method, ablation method or the like.

  In this case, the solvent for dissolving the organic semiconductor compound according to the present invention is not particularly limited as long as the organic semiconductor compound can be dissolved to prepare a solution with an appropriate concentration. Chain ether solvents such as diisopropyl 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 And aromatic solvents such as nitrobenzene and m-cresol, N-methylpyrrolidone, carbon disulfide and the like. Of these solvents, a solvent containing a non-halogen solvent is preferable, and a non-halogen solvent is preferable.

  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, 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 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 organic thin-film transistor (organic TFT) using the organic thin film formed using the organic-semiconductor compound concerning 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 thin film transistor material of the present invention is formed between the two electrodes, and on that, 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 thin film transistor 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 the output element 12 is, for example, a liquid crystal or an electrophoretic element, 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.

  Moreover, the organic TFT using the organic semiconductor material of the present invention can be applied to the technology introduced in, for example, SID2005, sessions 49-1, 2 and 3, and an a-Si transistor is used as the organic semiconductor transistor of the present invention. By replacing it, it is possible to obtain good characteristics.

  Hereinafter, as an example of the technology application, an organic electroluminescence element (organic EL element) including the organic TFT of the present invention will be described.

<< Organic EL element (Organic electroluminescence element) >>
The organic semiconductor device or the organic thin film transistor of the present invention can be provided in an organic electroluminescence element (also referred to as an organic EL element), and the organic EL element is, for example, an organic EL layer (organic layer, The organic compound layer is also sandwiched (also referred to as a sandwiched state), and these structures are prepared using a conventionally known layer structure, organic EL layer material, or the like. I can do it. For example, the literature etc. of Nature, 395 volumes, 151-154 pages can be referred.

  In emitting light from an organic EL element (for example, applied to a display device, a lighting device, etc.), the organic semiconductor device of the present invention or the present invention is obtained from the viewpoint of obtaining high light emission luminance and a long light emission lifetime. The organic thin film transistor of the invention is preferably provided.

<Display device>
The organic EL element may be used as a kind of lamp for illumination or exposure light source, a projection device that projects an image, or a display device (display) that directly recognizes a still image or a moving image. May be used as When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using two or more organic EL elements of the present invention having different emission colors.

  An example of a display device composed of the organic EL element of the present invention will be described with reference to the drawings.

  FIG. 3 is a schematic diagram illustrating an example of a display device including organic EL elements.

  It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element. The display 21 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.

  The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.

  FIG. 4 is a schematic diagram of the display unit A.

  The display unit A includes a wiring unit including a plurality of scanning lines 25 and data lines 26, a plurality of pixels 23, and the like on a substrate.

  The main members of the display unit A will be described below.

  In the drawing, the light emitted from the pixel 23 is extracted in the direction of the white arrow (downward). The scanning lines 25 and the plurality of data lines 26 in the wiring portion are each made of a conductive material, and the scanning lines 25 and the data lines 26 are orthogonal to each other in a lattice shape and are connected to the pixels 23 at the orthogonal positions (details are shown in FIG. Not shown).

  When a scanning signal is applied from the scanning line 25, the pixel 23 receives an image data signal from the data line 26 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.

  Next, the light emission process of the pixel will be described.

  FIG. 5 is a schematic diagram of a pixel.

  The pixel includes an organic EL element 100, a switching transistor 110, a driving transistor 120, a capacitor 130, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 100 for a plurality of pixels, and juxtaposing them on the same substrate.

  In FIG. 5, an image data signal is applied from the control unit B to the drain of the switching transistor 110 via the data line 60. When a scanning signal is applied from the control unit B to the gate of the switching transistor 110 via the scanning line 50, the driving of the switching transistor 110 is turned on, and the image data signal applied to the drain is supplied to the capacitor 130 and the driving transistor 120. Is transmitted to the gate.

  By transmitting the image data signal, the capacitor 130 is charged according to the potential of the image data signal, and the drive of the drive transistor 120 is turned on. The drive transistor 120 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 100, and the power supply line 70 connects to the organic EL element 100 according to the potential of the image data signal applied to the gate. Current is supplied.

When the scanning signal is moved to the next scanning line 50 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 130 maintains the potential of the charged image data signal even when the driving of the switching transistor 110 is turned off, the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When a scanning signal is next applied by sequential scanning, the driving transistor 120 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 100 emits light.

  That is, the organic EL element 100 emits light by providing a switching transistor 110 and a driving transistor 120 which are active elements for each of the organic EL elements 100 of the plurality of pixels, and the plurality of pixels 23 as shown in FIG. Each of the organic EL elements 100 that are provided emits light. Such a light emitting method is called an active matrix method.

  Here, the light emission of the organic EL element 100 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.

  The potential of the capacitor 130 may be maintained until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.

  In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these. Here, structural formulas of comparative organic semiconductor materials (also referred to as organic semiconductor compounds) used in the examples are shown below.

Example 1
<< Production of Organic Thin Film Transistor 1 >>
A Si oxide having a specific resistance of 0.01 Ω · cm as a gate electrode was formed with a thermal oxide film having a thickness of 2000 mm to form a gate insulating layer, and then surface treatment with octadecyltrichlorosilane was performed.

  On a Si wafer subjected to such a surface treatment, Comparative Compound 1 (Pentacene, manufactured by Aldrich, used after sublimation purification of a commercially available reagent) was added to toluene that was bubbled with nitrogen for 30 minutes in a nitrogen atmosphere. , Dissolved at a concentration of 5% by mass, spin-coated under a nitrogen atmosphere (rotation speed: 2500 rpm, 15 seconds), naturally dried to form a cast film, and heat-treated at 50 ° C. for 30 minutes in a nitrogen atmosphere Was given.

  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 1 having a source electrode and a drain electrode 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.

<< Production of Organic Thin Film Transistor 2 >>
Comparative compound 2 (2,3,9,10-tetrahexylpentacene) is described in Organic Letters, vol. 2 (2000), p85.

  An organic thin film transistor 2 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 2.

<< Production of Organic Thin Film Transistor 3 >>
Comparative compound 3 is described in J. Org. Am. Chem. Soc. , Vol. 123 (2001), p9486, supporting information.
An organic thin film transistor 4 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 4.

<< Production of Organic Thin Film Transistor 4 >>
Comparative compound 4 is described in J. Org. Am. Chem. Soc. , Vol. 127 (2005), p4986, supporting information.

  An organic thin film transistor 5 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 5.

<< Production of Organic Thin Film Transistors 5-11 >>
In the production of the organic thin film transistor 2, organic thin film transistors 5 to 11 were produced in the same manner except that the organic semiconductor material of the present invention described in Table 1 was used instead of the comparative compound 1.

<< Evaluation of carrier mobility and ON / OFF value >>
About the obtained organic thin-film transistors 1-11, the carrier mobility and ON / OFF value of each element were measured immediately after element preparation. In the present invention, the carrier mobility is obtained from the saturation region of the IV characteristic, and the ON / OFF ratio is obtained from the ratio of the drain current values when the drain bias is −50 V and the gate bias is −50 V and 0 V. It was.

  Further, the same evaluation was carried out for 48 hours after each element was placed in an environmental chamber at 40 ° C. and 90% RH, and then the carrier mobility / ON / OFF ratio was measured again.

  The obtained results are shown in Table 1.

In the organic thin film transistors 5 to 11 manufactured using the organic semiconductor material of the present invention, the carrier mobility and the ON / OFF ratio are excellent immediately after the manufacturing, and the mobility is 10 ⁻² even after the durability test. As described above, the ON / OFF ratio is 10 ⁵ units or more, and it can be seen that it has little deterioration with time and high durability.

It is a figure which shows the structural example of the organic TFT which concerns on this invention. It is a figure which shows one example of the schematic equivalent circuit schematic of an organic TFT sheet. It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. 4 is a schematic diagram of a display unit A. FIG. It is a schematic diagram of a pixel.

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
DESCRIPTION OF SYMBOLS 12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit 21 Display 23 Pixel 25 Scan line 26 Data line 27 Power supply line 100 Organic EL element 110 Switching transistor 120 Drive transistor 130 Capacitor A Display part B Control part

Claims (12)

An organic semiconductor material comprising a compound containing at least one biphenylene ring as a partial structure in a molecule. The organic compound according to claim 1, wherein the compound includes an aromatic condensed ring in which four or more rings are condensed as a partial structure, and the aromatic condensed ring includes at least one biphenylene ring as a partial structure. Semiconductor material. 2. The compound according to claim 1, wherein the compound includes an aromatic condensed ring in which five or more rings are condensed as a partial structure, and the aromatic condensed ring includes at least two biphenylene rings as the partial structure. Organic semiconductor material. The organic semiconductor material according to claim 1, wherein the compound has a partial structure represented by the following general formula (1).

[Wherein, R _1, R ₂ each represents a hydrogen atom, a halogen atom or a substituent, n1, n2 represents an integer of 0 to 3. ] The organic semiconductor material according to claim 4, wherein R _{1 in the} general formula (1) is a group represented by the following general formula (a).
Formula (a)
-C≡C-R
[Wherein, R represents a substituent. ] 5. The organic semiconductor material according to claim 4, wherein R ₁ and R _{2 in} the general formula (1) are each a group represented by the general formula (a). R in the general formula (a) is an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, or —Si (R ′) ₃ (where R ′ is The organic semiconductor material according to claim 5, wherein the organic semiconductor material represents a substituent. An organic semiconductor film comprising the organic semiconductor material according to claim 1. An organic material formed through a step of dissolving or dispersing the organic semiconductor material according to any one of claims 1 to 7 in an organic solvent, and applying and drying the obtained solution or dispersion. Semiconductor film. The organic-semiconductor device using the organic-semiconductor material of any one of Claims 1-7. An organic thin film transistor, wherein the organic semiconductor material according to claim 1 is used for a semiconductor layer. 8. An organic semiconductor film production comprising: dissolving or dispersing the organic semiconductor material according to claim 1 in an organic solvent, and applying and drying the obtained solution or dispersion. Method.

Images