JP5891646B2 - Novel organic semiconductor material and electronic device using the same - Google Patents

Description

  The present invention relates to a novel organic semiconductor material, and the obtained organic semiconductor material is extremely useful as an organic electronic material.

  In recent years, research and development of organic thin film transistors using organic semiconductor materials has been active. Organic semiconductor materials can be formed into thin films by a simple process using a wet process such as a printing method, spin coating method, etc., and have the advantage that the manufacturing process temperature can be lowered compared to conventional thin film transistors using inorganic semiconductor materials. There is. This enables formation on plastic substrates with generally low heat resistance, which can reduce the weight and cost of electronic devices such as displays, and is expected to be used in a variety of ways, including applications that take advantage of the flexibility of plastic substrates. it can.

Up to now, poly (3-alkylthiophene) (see Appl. Phys. Lett., 69 (26), 4108 (1996) of Non-Patent Document 1) or co-polymerization of dialkylfluorene and bithiophene as organic semiconductor materials. A combination (see Science, 290, 2123 (2000) of Non-Patent Document 2) and the like have been proposed.
These organic semiconductor materials have low solubility but do not go through a vacuum deposition process,
Thinning is possible by coating or printing.
However, these polymer materials are limited by the purification method, and it is very troublesome to obtain a high-purity material, and the problem is that the quality is not stable due to the presence of molecular weight and molecular weight distribution. It has become.

In addition, an acene-based material such as pentacene has been reported as an organic semiconductor material of a low molecular derivative (see, for example, Patent Document 1).
Organic thin-film transistors using pentacene as an organic semiconductor layer have been reported to have a relatively high mobility, but these acene-based materials have extremely low solubility in general-purpose solvents. When thinning as a layer, it is necessary to go through a vacuum deposition process. Therefore, it does not meet the expectation for an organic semiconductor material that a thin film can be formed by a simple process such as coating and printing as described above.

  In addition, although some low molecular organic semiconductor materials having solubility have been reported so far, the film produced by the wet process is amorphous or a continuous film is obtained for crystal habit derived from each material. However, there is a problem that the characteristics of each element greatly vary, and good characteristics cannot be obtained. For example, WO2010 / 000670 International Publication Specification of Patent Document 2, JP2009-054810A of Patent Document 3, Advanced Materials 2009, 21, 213-216. If the molecule has a π-stacked structure in the crystal, such as the dithienobenzodithiophene derivative described in 1), the crystal form tends to be needle-like and cannot be formed into a continuous thin film state, Even in the crystal, the anisotropy of the charge transport property is increased and the variation in the property of each element is increased, which is not suitable for practical use. In particular, it is difficult to predict the crystal structure including the crystal shape from the molecular structure, and further material development is still desired.

  In order to solve the above-mentioned problems, the present invention provides an organic semiconductor material having excellent characteristics in which a continuous film can be formed by two-dimensional crystal growth by a simple process such as coating, printing or vapor deposition. For the purpose.

As a result of intensive studies to achieve the above object, the present inventors have found that the above-mentioned problems can be solved by introducing a specific modifying group into a specific site of the dithienobenzodithiophene skeleton, thereby completing the present invention. It came to.
That is, the gist of the present invention is achieved by the following.
(1) “An organic semiconductor material having a structure represented by the following general formula (I):

（上記一般式（Ｉ）中、Ｘはアリール基である。）」

(In the above general formula (I) , X is an aryl group .) "

( 2 ) "Charge transporting member containing the organic semiconductor material according to (1) above."
(3 ) “An organic electronic device comprising the charge transporting member according to ( 2 ) above.”
( 4 ) “The organic electronic device according to ( 3 ) includes an organic semiconductor layer, and the first and second electrodes in a pair separated from each other are applied with a voltage, thereby the first An organic thin film transistor comprising a third electrode having a function of controlling a current flowing between the second electrode and the second electrode. "
( 5 ) "The first electrode and the second electrode are separated from each other via the organic semiconductor layer, and an insulating film is provided between the third electrode and the organic semiconductor layer. The organic thin-film transistor according to ( 4 ) above, which is characterized by the above. "
( 6 ) “Display device in which a display pixel is driven by the organic thin film transistor according to ( 4 ) or ( 5 ).”

  As will be apparent from the following detailed and specific description, the present invention solves the above-mentioned problems, and a continuous film can be formed by two-dimensional crystal growth by a simple process such as coating or printing, An extremely excellent effect of providing an organic semiconductor material having excellent characteristics is achieved.

It is the schematic of an organic thin-film transistor. It is sectional drawing of an example of the transistor array for driving a display image element. It is a figure showing an example of the transistor array for driving a display image element. It is an LC-MC spectrum of the compound of the present invention (Ex. 1). It is an LC-MC spectrum of the compound of the present invention (Ex. 2). It is an LC-MC spectrum of the compound of the present invention (Ex. 3). 4 is a SEM image of a transistor manufactured in Comparative Example 2. 10 is a SEM image of a transistor manufactured in Comparative Example 3.

  Hereinafter, the present invention will be described with reference to embodiments. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist thereof.

First, the structure of the organic semiconductor material of the present invention will be described.
The structure of the organic semiconductor material of the present invention is represented by the following general formula (I) as described above.

（上記一般式（Ｉ）中、Ｘはアリール基である。）」

(In the above general formula (I) , X is an aryl group .) "

Next, the manufacturing method of the organic semiconductor of this invention is demonstrated.
The method for synthesizing the organic semiconductor material of the present invention is not particularly limited, and it can be synthesized by various known methods. The organic semiconductor material of the present invention may introduce a triple double bond site at both ends after constructing a dithienobenzodithiophene skeleton, or construct a dithienobenzodithiophene skeleton after introducing a double bond site. May be.

After constructing the dithienobenzodithiophene skeleton, when introducing triple bond sites at both ends, for example, Castro-Stephens acetylene coupling and Sonogashira-Hagiwara cross-coupling reaction using an alkynyl compound having a halogen compound and a terminal hydrogen, Stille coupling reaction using alkynyltin compound and halogen compound, Suzuki-Miyaura coupling reaction using alkynylboron compound and halogen compound, Kumada cross-coupling using alkynyl Grignard reagent and halogen compound, alkynylzinc reagent and halogen compound Seyfers-Gilbert Archi, which uses a α-diazophosphonate compound to add one carbon from a ketone or aldehyde derivative and converts it to an alkyne. Synthesis.
Among them, the Sonogashira-Hagiwara cross-coupling reaction and Negishi cross-coupling reaction are easy to adjust intermediates, less restricted to other functional groups, high reactivity, high yield, etc. It is effective from the viewpoint. More preferably, the Sonogashira-Hagiwara cross-coupling reaction is effective because of the mild reaction conditions.
As an example, the manufacturing method of the organic-semiconductor material of this invention using the Sonogashira-Hagiwara cross coupling reaction is demonstrated.

  The organic semiconductor material of the present invention can be obtained by reacting an alkyne compound having a terminal hydrogen and a halogen compound in the presence of a base, a solvent and a catalyst as shown in the following reaction formula. Note that A and B below may be reversed.

  Examples of the base include, but are not limited to, amines, metal alcosides, metal hydrides, and organic lithium compounds. Examples include triethylamine, diisopropylamine, diisopropylethylamine, piperidine, potassium t-butoxide, sodium t-butoxide, and lithium t-. Butoxide, potassium 2-methyl-2-butoxide, sodium 2-methyl-2-butoxide, sodium methoxide, sodium ethoxide, potassium ethoxide, potassium methoxide, sodium hydride, potassium hydride, methyllithium, ethyllithium, Propyl lithium, n-butyl lithium, s-butyl lithium, t-butyl lithium, phenyl lithium, lithium naphthylide, lithium amide, lithium diisopropylamide, etc. That. Among them, a relatively weak base is preferable because it has little influence on other functional groups (for example, amines such as triethylamine, diisopropylamine, diisopropylethylamine, and piperidine).

Examples of the palladium catalyst include palladium bromide, palladium chloride, palladium iodide, palladium cyanide, palladium acetate, palladium trifluoroacetate, palladium acetylacetonate [Pd (acac) ₂ ], diacetate bis (triphenylphosphine) palladium [Pd (OAc) ₂ (PPh ₃ ) ₂ ], tetrakis (triphenylphosphine) palladium [Pd (PPh ₃ ) ₄ ], dichlorobis (acetonitrile) palladium [Pd (CH ₃ CN) ₂ Cl ₂ ], dichlorobis (benzonitrile) palladium _{[Pd (PhCN) 2 Cl 2} ], dichloro [1,2-bis (diphenylphosphino) ethane] palladium [Pd (dppe) Cl _2], dichloro [1,1-bis (diphenylphosphino) Ferose ] Palladium [Pd (dppf) Cl _2], dichlorobis (tricyclohexylphosphine) palladium _{[Pd [P (C 6 H 11} ) 3] 2 Cl 2 ], dichlorobis (triphenylphosphine) palladium [Pd (PPh _{3) 2} Cl ₂ ], tris (dibenzylideneacetone) dipalladium [Pd2 (dba) 3], bis (dibenzylideneacetone) palladium [Pd (dba) ₂ ], and the like, but tetrakis (triphenylphosphine) palladium [Pd ( Phosphines such as PPh ₃ ) ₄ ], dichloro [1,2-bis (diphenylphosphino) ethane] palladium [Pd (dppe) Cl ₂ ], dichlorobis (triphenylphosphine) palladium [Pd (PPh ₃ ) ₂ Cl ₂ ], etc. System catalysts are preferred.

  In addition to the above, a palladium catalyst synthesized by reaction of a palladium complex and a ligand in the reaction system can be used as the palladium catalyst. Examples of the ligand include triphenylphosphine, trimethylphosphine, triethylphosphine, tris (n-butyl) phosphine, tris (tert-butyl) phosphine, bis (tert-butyl) methylphosphine, tris (i-propyl) phosphine, tris. Cyclohexylphosphine, tris (o-tolyl) phosphine, tris (2-furyl) phosphine, 2-dicyclohexylphosphinobiphenyl, 2-dicyclohexylphosphino-2′-methylbiphenyl, 2-dicyclohexylphosphino-2 ′, 4 ′, 6'-triisopropyl-1,1'-biphenyl, 2-dicyclohexylphosphino-2 ', 6'-dimethoxy-1,1'-biphenyl, 2-dicyclohexylphosphino-2'-(N, N'-dimethyl Amino) biphenyl 2-diphenylphosphino-2 ′-(N, N′-dimethylamino) biphenyl, 2- (di-tert-butyl) phosphino-2 ′-(N, N′-dimethylamino) biphenyl, 2- (di- tert-butyl) phosphinobiphenyl, 2- (di-tert-butyl) phosphino-2′-methylbiphenyl, diphenylphosphinoethane, diphenylphosphinopropane, diphenylphosphinobutane, diphenylphosphinoethylene, diphenylphosphinoferrocene, Ethylenediamine, N, N ′, N ″, N ′ ″-tetramethylethylenediamine, 2,2′-bipyridyl, 1,3-diphenyldihydroimidazolylidene, 1,3-dimethyldihydroimidazolylidene, diethyldihydroimidazo Lilidene, 1,3-bis (2,4,6-trimethyl Ruphenyl) dihydroimidazolylidene and 1,3-bis (2,6-diisopropylphenyl) dihydroimidazolylidene are mentioned, and a palladium catalyst coordinated with any of these ligands is used as a cross-coupling catalyst. Can do.

  The reaction solvent is preferably one that does not have a functional group capable of reacting with the raw material and that can dissolve the raw material in an appropriate amount. Water, methanol, ethanol, isopropanol, butanol, 2-methoxyethanol 1,2-dimethoxyethane, bis (2-methoxyethyl) ether and other alcohols and ethers, dioxane, tetrahydrofuran and other cyclic ethers, benzene, toluene, xylene, chlorobenzene, dichlorobenzene, dimethyl sulfoxide (DMSO) N, N-dimethylformamide (DMF), N, N-dimethylacetamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. These solvents may be used alone or in combination of two or more. These solvents are preferably dried and degassed in advance.

The temperature of the above reaction is appropriately set depending on the reactivity of the raw materials used and the reaction solvent, and can usually be carried out in the range of 0 ° C. to 200 ° C. In either case, the reaction temperature should be kept below the boiling point of the solvent. preferable. In addition, it is preferable from the viewpoint of yield to suppress to a temperature at which the elimination reaction occurs or less, specifically, a range of room temperature to 150 ° C. is preferable, a range of room temperature to 120 ° C. is particularly preferable, and a range of room temperature to 120 ° C. is most preferable. It is in the range of 100 ° C.
The reaction time in the above reaction can be appropriately set in the reactivity of the raw material used, is preferably 1 to 72 hours, and more preferably 1 to 24 hours.

The above alkenyl compound can be synthesized by various methods.
The following method of deprotection after Sonogashira-Hagiwara cross-coupling reaction between halogen compound and terminal protected hydrogenated alkyne

(Here, the Pd catalyst, the base and the solvent are the same as those described above. The base used for the deprotection in the second stage is not particularly limited. However, unlike the first stage (coupling reaction), the base is somewhat strong. Better results, such as potassium hydroxide, sodium hydroxide, lithium hydroxide, etc.),
The following, a method of undergoing deprotection after the reaction between the hydrogen compound and the end-protected alkynyllithium reagent,

Etc. can be mentioned as an example.
In the above formula, the base and solvent used for deprotection are as described above, but the solvent used in the first step is preferably one that does not react with the lithium reagent and that forms a complex with the lithium reagent in the solvent. . Examples thereof include 1,2-dimethoxyethane, diethyl ether, tetrahydrofuran and the like. From the viewpoint of preventing side reactions, the low temperature condition is preferably 0 ° or less, particularly preferably −40 ° or less, and most preferably −70 ° C. or less.
As described above, induction from a hydrogen compound or a halogen compound is easy, and a desired alkenyl compound can be obtained using these techniques.

  The above halogen compounds can also be synthesized by various conventionally known methods. As an example, a method of directly reacting a halogenating agent, a method of reacting with a halogenating agent after lithiation once, and the like are taken as an example. Can be mentioned. Moreover, the triflate produced | generated by making trifluoromethanesulfonic anhydride react with a hydroxyl group can be used similarly to a halide. Of these, iodine, bromine and triflate are preferred from the viewpoint of reactivity.

  When a dithienobenzodithiophene skeleton is constructed after introducing a triple bond site, it can be synthesized by the following method.

  By using a thiophene derivative in which an alkynyl group is substituted at a target position, an organic semiconductor material in which an alkynyl group is selectively introduced at the 2-position, 3-position, or both positions can be efficiently produced.

  The organic semiconductor material of the present invention obtained as described above is used after removing impurities such as the catalyst used in the reaction, unreacted raw materials, and salts. These purification methods include conventional methods such as reprecipitation, column chromatography, adsorption, extraction (including Soxhlet extraction), ultrafiltration, dialysis, and the use of scavengers to remove the catalyst. Can be used. Since contamination with impurities adversely affects the semiconductor characteristics, it is desirable to make the purity as high as possible. A material having excellent solubility has fewer restrictions on these purification methods, and as a result, has a positive effect on device characteristics.

When the semiconductor material of the present invention obtained by the above production method is dissolved in a solvent such as dichloromethane, tetrahydrofuran, chloroform, toluene, dichlorobenzene and xylene, a thin film can be formed by coating on a support. .
Examples of film forming methods include spin coating, casting, dipping, ink jet, doctor blade, screen printing, dispensing, and the like. A thin film can be formed by a known wet film forming method. Is possible.
Further, depending on the casting method or the like, it is possible to take a form of a flat crystal or a thick film state. Depending on the device to be produced, an appropriate combination is selected from the above-described film forming methods or solvents.
Of course, the film can also be formed by a dry process such as a vacuum deposition method.

  In the organic thin film transistor of the present invention, the thickness of the organic semiconductor layer is not particularly limited, but a uniform thin film (that is, there is no gap or hole that adversely affects the carrier transport property of the organic semiconductor layer) is formed. The thickness is selected. The thickness of the organic semiconductor thin film is generally 1 μm or less, particularly preferably 5 to 100 nm. In the organic thin film transistor of the present invention, the organic semiconductor layer formed using the above compound as a component is formed in contact with the source electrode, the drain electrode, and the insulating film.

These thin films, thick films, or crystals function as charge transporting members for various functional elements such as photoelectric conversion elements, thin film transistors, and light emitting elements, and a variety of electronic devices can be manufactured using this semiconductor material. It is.
An example of an electronic device is a device that has two or more electrodes, the current flowing between the electrodes and the voltage generated are controlled by electricity, light, magnetism, chemical substances, etc., or the applied voltage or current Thus, a device that generates light, an electric field, or a magnetic field can be used. In addition, for example, an element that controls current or voltage by application of voltage or current, an element that controls voltage or current by application of a magnetic field, an element that controls voltage or current by the action of a chemical substance, or the like can be given. Examples of this control include rectification, switching, amplification, and oscillation.
Corresponding devices currently implemented with inorganic semiconductors such as silicon include resistors, rectifiers (diodes), switching elements (transistors, thyristors), amplifier elements (transistors), memory elements, chemical sensors, etc., or these elements Combinations and integrated devices. Moreover, a solar cell that generates an electromotive force by light, and an optical element such as a photodiode or a phototransistor that generates a photocurrent can also be used.

  An example of an electronic device suitable for applying the organic semiconductor material of the present invention includes an organic thin film transistor, that is, an organic field effect transistor (OFET). Hereinafter, this FET will be described in detail.

FIG. 1 is a schematic structural view for explanation. In the figure, (A) to (D) are schematic structures of the organic thin film transistor according to the present invention. The organic semiconductor layer (1) of the organic thin film transistor according to the present invention contains the organic semiconductor compound of the present invention. The organic thin film transistor of the present invention includes a third electrode on a spatially separated first electrode (source electrode (2)), second electrode (drain electrode (3)) and a support (substrate) (not shown). An electrode (gate electrode (4)) is provided, and an insulating film (5) may be provided between the gate electrode (4) and the organic semiconductor layer (1). In the organic thin film transistor, the current flowing in the organic semiconductor layer (1) between the source electrode (2) and the drain electrode (3) is controlled by applying a voltage to the gate electrode. It is important that the amount of current flowing between the source electrode (2) and the drain electrode (3) can be greatly modulated by the voltage application state of 4). This means that a large current flows when the transistor is driven, and no current flows when the transistor is not driven.
The organic thin film transistor of the present invention can be provided on a support, and for example, a commonly used substrate such as glass, silicon, or plastic can be used. In addition, by using a conductive substrate, it can also be used as a gate electrode, and a structure in which a gate electrode and a conductive substrate are stacked can be used. However, the flexibility of a device to which the organic thin film transistor of the present invention is applied. When characteristics such as light weight, low cost, and impact resistance are desired, a plastic sheet is preferably used as the support.
Examples of the plastic sheet include polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, cellulose triacetate, and cellulose acetate propionate. Is mentioned.
Moreover, the organic thin-film transistor of this invention can provide the extraction electrode from each electrode as needed.

Next, components other than the organic semiconductor layer in the organic thin film transistor of FIG. 1 will be described.
The organic semiconductor layer (1) is formed in contact with the first electrode (source electrode), the second electrode (drain electrode), and, if necessary, the insulating film (5).
The insulating film (5) will be described.
Various insulating film materials can be used for the insulating film used in the organic thin film transistor of the present invention. For example, silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, titanium oxide, tantalum oxide, tin oxide, vanadium oxide, barium strontium titanate, zirconium barium titanate, lead zirconate titanate, lead lanthanum titanate, titanate Examples thereof include inorganic insulating materials such as strontium, barium titanate, barium magnesium fluoride, bismuth tantalate niobate, and yttrium trioxide.

Further, for example, polymer materials such as polyimide, polyvinyl alcohol, polyvinylphenol, polyester, polyethylene, polyphenylene sulfide, unsubstituted or halogen atom-substituted polyparaxylylene, polyacrylonitrile, cyanoethyl pullulan, and the like can be used.
Further, two or more of the above insulating materials may be used in combination. The material is not particularly limited, but among them, a material having low conductivity is preferable.

  Examples of the method for producing the insulating film layer using the above materials include a CVD method, a plasma CVD method, a plasma polymerization method, a dry process such as a vapor deposition method, a spray coating method, a spin coating method, a dip coating method, an ink jet method, and a cast method. Examples thereof include wet processes such as coating, blade coating, and bar coating.

Next, interface modification between the organic semiconductor layer (1) and the insulating film (5) will be described.
In the organic thin film transistor of the present invention, an organic thin film may be provided between these layers for the purpose of improving the adhesion between the insulating film and the electrode and the organic semiconductor layer, reducing the gate voltage, and reducing the leakage current. The organic thin film is not particularly limited as long as it does not chemically affect the organic semiconductor layer. For example, an organic molecular film or a polymer thin film can be used.

  Specific examples of organic molecular films include octyltrichlorosilane, octadecyltrichlorosilane, hexamethylenedisilazane, phenyltrichlorosilane, benzenethiol, trifluorobenzenethiol, perfluorobenzenethiol, and perfluorodecanethiol. A ring agent is mentioned. As the polymer thin film, the above-described polymer insulating film materials can be used, and these may function as a kind of insulating film. The organic thin film may be subjected to an anisotropic treatment by rubbing or the like.

Next, the electrode which comprises an organic thin-film transistor is demonstrated.
The gate electrode, source electrode, and gate electrode used in the organic thin film transistor of the present invention are not particularly limited as long as they are conductive materials, such as platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony, lead, Tantalum, indium, aluminum, zinc, magnesium, etc., and their alloys and conductive metal oxides such as indium / tin oxide, or inorganic and organic semiconductors whose conductivity has been improved by doping, such as silicon single crystals, Examples thereof include polysilicon, amorphous silicon, germanium, graphite, polyacetylene, polyparaphenylene, polythiophene, polypyrrole, polyaniline, polythienylene vinylene, polyparaphenylene vinylene, a complex of polyethylenedioxythiophene and polystyrene sulfonic acid.

The source electrode and the drain electrode are preferably those having low electrical resistance at the contact surface with the semiconductor layer among the above-described conductivity.
As a method for forming an electrode, a method of 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 materials as a raw material, a metal such as aluminum or copper There is a method of etching using a resist by thermal transfer, ink jet or the like on a foil. Alternatively, the conductive polymer solution or dispersion, or the conductive fine particle dispersion may be directly patterned by ink jetting, or may be formed from the 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.

The organic thin film transistor of the present invention may be provided with an extraction electrode from each electrode as necessary.
The organic thin film transistor of the present invention is stably driven even in the atmosphere, but a protective layer is used as necessary for protection from mechanical destruction, protection from moisture and gas, or protection for the convenience of device integration. Can also be provided.

The organic thin film transistor of the present invention described above can be suitably used as an element for driving various conventionally known display image elements such as liquid crystal, electroluminescence, electrochromic, electrophoresis, and so on. It is possible to produce a display called “paper”.
The display device of the present invention includes, for example, a liquid crystal display element in a liquid crystal display device, an organic or inorganic electroluminescence display element in an EL display device, and a display element such as an electrophoretic display element in an electrophoretic display device as one display pixel. A plurality of display elements are arranged in a matrix in the X and Y directions.
The display element includes the organic thin film transistor of the present invention as shown in FIG. 2 as a switching element for applying a voltage or supplying a current to the display element. The display device of the present invention includes a plurality of the switching elements corresponding to the number of the display elements, that is, the number of display pixels.
The display element includes, in addition to the switching element, for example, a substrate, an electrode such as a transparent electrode, a polarizing plate, a color filter, and the like. However, these components are not particularly limited and may be used depending on the purpose. Can be appropriately selected, and conventionally known ones can be used.

When the display device forms a predetermined image, for example, the switching elements arbitrarily selected from the switching elements arranged in a matrix as shown in FIG. 3 are used as the corresponding display elements. By configuring the switch to be turned on or off only when voltage is applied or current is supplied, and to be turned off or on at other times, display of the display device can be performed at high speed and with high contrast.
As an image display operation in the display device, an image or the like is displayed by a conventionally known display operation.
For example, in the case of the liquid crystal display element, an image or the like is displayed by applying a voltage to the liquid crystal to control the molecular arrangement of the liquid crystal.
In the case of the organic or inorganic electroluminescence display element, an image or the like is displayed by supplying a current to a light emitting diode formed of an organic or inorganic film to cause the organic or inorganic film to emit light.
In the case of the electrophoretic display element, for example, a voltage is applied to white and black colored particles charged to different polarities, and the particles are electrophoresed between electrodes in a predetermined direction to generate an image or the like. Is displayed.

The display device can be manufactured by a simple process such as coating and printing of the switching element, and can use a substrate that cannot withstand high-temperature processing such as a plastic substrate or paper, and can be a large-area display. However, the switching element can be fabricated with energy saving and low cost.
Further, an IC in which the organic thin film transistor of the present invention is integrated can be used as a device such as an IC tag.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples unless it exceeds the gist.

  In the following, the identification of the compound in the examples is NMR spectrum (JNM-ECX (trade name) 500 MHz, manufactured by JEOL), mass spectrometry (GC-MS, GCMS-QP2010 Plus (trade name), manufactured by Shimadzu Corporation), mass spectrometry (LC-TofMS, Alliance-LCT Premier (trade name), manufactured by Waters, using ASAP probe), elemental analysis (CHN) (CHN recorder MT-2, manufactured by Yanagimoto Seisakusho), elemental analysis (S) (ion chromatography → -Anion analysis system DX320 (trade name, manufactured by Dionex) was used.

  Hereinafter, synthesis examples of intermediates used in the examples are shown.

[Synthesis Example 1]
(Synthesis of Compound 2 below)

Compound 1 (12.7 g, 42 mmol) synthesized by the method described in Advanced Materials, 2009, 21, 213-216. Of Non-Patent Document 3 was placed in a 2-liter round bottom flask, and replaced with argon gas. Then, dehydrated chloroform (600 ml) and acetic acid (600 ml) were added, and the internal temperature of the container was kept at 0-3 ° C. using an ice bath. Next, N-iodosuccinimide (20.8 g, 92.4 mmol) was gradually added under light shielding. After stirring for 1 hour, the ice bath was removed, the temperature was returned to room temperature, and stirring was continued overnight. The precipitate was collected by filtration, and the precipitate was washed with a saturated aqueous sodium hydrogen sulfite solution followed by ethanol, toluene, and ethanol. The precipitate was dried under vacuum to give a pale yellow solid. This contained a small amount of the 1-substituted product in addition to the 2-substituted compound 2, but it was not separated at this stage and used as it was without purification in the following reaction.
Yield 21.5 g, Yield 92.3%
Mass spectrometry: GC-MS m / z = 554 (M +), 428 (M + -I)

(Synthesis of Compound 3 below)

A 300 mL round bottom flask was charged with compound 2 (2.55 g, 4.60 mmol) and copper iodide (43.7 mg, 0.23 mmol), and replaced with argon gas, followed by tetrahydrofuran (hereinafter THF). , 100 mL), diisopropylethylamine (6.5 mL), dichlorobis (triphenylphosphine) palladium (II) (hereinafter, PdCl ₂ (PPh ₃ ) ₂ ) 97.2 mg, 0.138 mmol) Trimethylsilylacetylene (1.4 mL, 10.12 mmol) was gradually added while stirring. The mixture was stirred at room temperature overnight to obtain a red uniform solution. Water (200 mL) and toluene (100 mL) were added and the organic layer was separated. The aqueous layer was extracted three times with toluene (50 mL), and the combined organic layer was washed with saturated brine (100 mL) and dried over sodium sulfate. The filtrate was concentrated and subjected to column purification (stationary phase: silica gel, mobile phase: toluene) to obtain a red solid. This was recrystallized from toluene / acetonitrile to obtain Compound 3 as yellow needle crystals.
Yield: 1.35 g, Yield: 59.1%
The analysis results of Compound 3 are shown below.
Mass spectrometry: LC-MS m / z = (C 24 H 22 S 4 Si 2) 494.0 ( found); 494.0 (theoretical)
From the above analysis results, it was confirmed that the synthesized product was consistent with the structure of Compound 3.

(Synthesis of Compound 4 below)

Compound 3 (2.3 g, 4.65 mmol), THF (100 mL), methanol (20 mL) are placed in a 300 mL round bottom flask, and potassium hydroxide solution (1.2 g is dissolved in 15 mL of water). Was added. The mixture was stirred as it was for 3 hours, water (100 mL) and methanol (100 mL) were added, and the deposited precipitate was collected by filtration. The precipitate was washed with water and methanol in this order, and dried under vacuum to obtain Compound 4 as a brown solid. Yield 1.62 g, 99.5%
The analysis results of Compound 4 are shown below.
Mass spectrometry: LC-MS m / z = (C ₁₈ H ₆ S ₄ ) 349.9 (actual value); 349.9 (theoretical value)
From the above analysis results, it was confirmed that the synthesized product was consistent with the structure of Compound 4.

[Example 1]
<Synthesis of the following compound (actual 1)>

Compound 4 (600 mg, 1.71 mmol) and copper iodide (16.2 mg) were placed in a 100 mL round-bottom flask, and replaced with argon gas, followed by tetrahydrofuran (hereinafter THF, 50 mL), diisopropyl. Ethylamine (3.0 mL) and PdCl ₂ (PPh ₃ ) ₂ (36.1 mgl) were added, and iodobenzene (421 μLl) was gradually added with sufficient stirring. The mixture was stirred at room temperature for 72 hours. 1N hydrochloric acid (100 mL) was added, and the precipitate was collected by filtration.
The precipitate was washed with water, ethyl acetate, toluene and methanol in this order, and dried under vacuum to obtain a brown solid (800 mg).
This was subjected to Soxhlet extraction (chlorobenzene) to obtain a pale yellow solid. (Yield 700 mg, Yield 81.4%)
Subsequently, temperature gradient sublimation purification was performed to obtain a compound (Ex. 1) as yellow crystals. (Yield 300 mg, Yield 34.9%)
The analysis results of the compound (Ex. 1) are shown below. FIG. 1 shows a time-of-flight mass spectrometry (hereinafter, Tof-MS) spectrum of the compound (Ex. 1). In addition, the actual measurement value obtained from the spectrum and the theoretical value obtained from the composition formula are shown together.
Mass analysis results: LC-TofMS m / z = (C ₃₀ H ₁₄ S ₄ ) 501.9 (100%), 502.9, 503.9 (actual measured value); 502.0 (100%), 503.0 , 504.0 (theoretical value)
From the above analysis results, it was confirmed that the synthesized product was consistent with the structure of the compound (Ex. 1).

[Example 2]
<Synthesis of the following compound (act 2)>

In Example 1, a compound (Act 2) was synthesized in the same manner except that 4-iodotoluene was used instead of iodobenzene. A light yellow solid was obtained after Soxhlet extraction. (Yield 700 mg, Yield 82.5%)
Subsequently, temperature gradient sublimation purification was carried out to obtain a compound (Ex. 2) as yellow crystals. (Yield 280 mg, Yield 33.0%)
The analysis results of the compound (Act 2) are shown below. FIG. 2 shows the Tof-MS spectrum of the compound (Ex. 2).
In addition, the actual measurement value obtained from the spectrum and the theoretical value obtained from the composition formula are shown together.
Mass analysis results: LC-TofMS m / z = (C ₃₂ H ₁₈ S ₄ ) 530.2 (100%), 531.2, 532.2 (actual measured value); 530.0, 531.0, 532.0 (Theoretical value)
From the above analysis results, it was confirmed that the synthesized product was consistent with the structure of the compound (Ex. 2).

Example 3
<Synthesis of the following compound (act 3)>

Compound (Act 3) was synthesized in the same manner as in Example 1 except that 2-bromonaphthalene was used instead of iodobenzene, toluene was used instead of THF, and the reaction temperature was changed from room temperature to 110 ° C. It was. A light yellow solid was obtained after Soxhlet extraction. (Yield 940 mg, Yield 70.0%)
Subsequently, temperature gradient sublimation purification was performed to obtain a compound (Ex. 3) as yellow crystals. (Yield 310 mg, Yield 23.0%)
The analysis results of the compound (Act 3) are shown below.
Mass spectrometry: LC-TofMS (m / z ) = (C 38 H 18 S 4) 602.2 (100%), 603.30, 604.2 ( found); 602.0, 603.0, 604. 0 (theoretical value)
From the above analysis results, it was confirmed that the synthesized product was consistent with the structure of the compound (Act 3).

Example 4
<Production of organic thin film transistor>
Using the compound synthesized in Example 1 (Act 1), a field effect transistor having the structure of FIG.
An N-doped silicon substrate having a 300 nm thick thermal oxide film was immersed in concentrated sulfuric acid for 24 hours and washed.
The cleaned silicon substrate was immersed in a toluene solution (1 mM) of a silane coupling agent (n-octyltrichlorosilane) and subjected to ultrasonic treatment for 5 minutes to form a monomolecular film on the silicon oxide film surface.
With respect to the board | substrate produced above, the compound (Actual 1) obtained in Example 1 (sublimation purification was performed before use) was vacuum-deposited (back pressure: 10 ⁻⁴ Pa, deposition rate: 0.1 kg / s. The organic semiconductor layer was formed by substrate temperature of 100 ° C., semiconductor film thickness: ˜50 nm.

Source and drain electrodes were formed by channel-depositing gold on the top of the organic semiconductor layer using a shadow mask (back pressure: 10 ⁻⁴ Pa, deposition rate: 1-2 Å / s, film thickness: 50 nm) (channel length) 50 μm, channel width 2 mm). The organic semiconductor layer and the silicon oxide film at portions different from the electrodes were scraped off, and a conductive paste (conductive paste, manufactured by Fujikura Kasei Co., Ltd.) was applied to the portions, and the solvent was dried. Using this portion, a voltage was applied to the silicon substrate as the gate electrode.
The electric characteristics of the FET (field effect transistor) element thus obtained were evaluated in the atmosphere using an Agilent semiconductor parameter analyzer 4156C. As a result, the characteristics as a p-type transistor element were shown.
In addition, the following formula | equation was used for calculation of the field effect mobility of an organic thin-film transistor.

[Equation 1]
Ids = μCinW (Vg−Vth) ² / 2L
(Where Cin is the capacitance per unit area of the gate insulating film, W is the channel width, L is the channel length, Vg is the gate voltage, Ids is the source / drain current, μ is the mobility, and Vth is the gate that the channel begins to form. (It is the threshold voltage.)

When the characteristics of the manufactured thin film transistor were evaluated, p-type transistor driving was shown.
Moreover, as a result of analyzing the produced transistor by SEM, the thin film of the compound (Ex. 1) had a film structure that grew densely in a two-dimensional plane.

Example 5
In Example 4, an organic thin film transistor was produced and evaluated in the same manner except that the compound (Act 2) was used instead of the compound (Act 1) as the organic semiconductor material.
As a result, when the characteristics of the manufactured thin film transistor were evaluated, p-type transistor driving was shown. From the SEM image, as in Example 4, the thin film of the compound (Ex. 2) had a film structure that grew densely in a two-dimensional plane.

Example 6
In Example 4, an organic thin film transistor was produced and evaluated in the same manner except that the compound (Act 3) was used instead of the compound (Act 1) as the organic semiconductor material.
As a result, when the characteristics of the manufactured thin film transistor were evaluated, p-type transistor driving was shown. From the SEM image, the thin film of the compound (Ex. 3) had a film structure that grew densely in a two-dimensional plane as in Example 4.

[Comparative Example 1]
Compound 1 (dithienobenzothiophene) described in Synthesis Example 1 was dissolved in THF, and the solution was cast on a silicon wafer. As the solvent was dried, Compound 1 precipitated as needle crystals, and a continuous film usable as a charge transport member could not be obtained.

[Comparative Example 2]
An organic thin film transistor was produced in the same manner as in Example 4 except that Compound 1 was used. Although the characteristics were evaluated, it did not operate as a transistor.
When observed with SEM, acicular crystals grew, and as in Comparative Example 1, a continuous film usable as a charge transport member could not be obtained. FIG. 7 shows the SEM results.

[Comparative Example 3]
With reference to the method described in Non-Patent Document 3, Advanced Materials, 2009, 21, 213-216., Compounds (ratio 1) were synthesized by the following route. Colorless needles. Mp 184 ° C.

As shown in FIG. 1- (B), a 0.5 wt% mesitylene solution of the compound (ratio 1) is cast on a silicon wafer having a 300 nm-thick thermal oxide film patterned on a gold electrode. A thin film transistor was manufactured. Although the characteristics of the transistor were evaluated, only an element having a mobility of about 1E-5 was obtained because the transistor does not operate as a transistor.
When observed with SEM, needle-like crystals grew, and as in Comparative Example 1, a continuous film suitable for use as a thin-film charge transport member could not be obtained. FIG. 8 shows the result of SEM.

  In order to solve the above-mentioned problems, the present invention provides an organic semiconductor material having excellent characteristics in which a continuous film can be formed by two-dimensional crystal growth by a simple process of coating, printing or vapor deposition. be able to.

1 Organic Semiconductor Layer 2 Source Electrode 3 Drain Electrode 4 Gate Electrode 5 Gate Insulating Film

Japanese Patent Application Laid-Open No. 5-05568 WO2010 / 000670 published specification JP 2009-054810 A

Appl. Phys. Lett., 69 (26), 4108 (1996). Science, 290, 2123 (2000). Advanced Materials, 2009,21,213-216

Claims (7)

An organic semiconductor material having a structure represented by the following general formula (I):

(In the above general formula (I) , X is an aryl group .)   A charge transporting member comprising the organic semiconductor material according to claim 1. An organic electronic device comprising the charge transporting member according to claim 2 . The organic electronic device according to claim 3 , comprising an organic semiconductor layer and applying a voltage to a pair of first and second electrodes separated from each other, whereby the first electrode and the first electrode are applied. An organic thin film transistor comprising a third electrode having a function of controlling a current flowing between two electrodes. The first electrode and the second electrode are separated from each other through the organic semiconductor layer, and an insulating film is provided between the third electrode and the organic semiconductor layer. The organic thin film transistor according to claim 4 . Display apparatus characterized by display pixels are driven by the organic thin film transistor according to claim 4 or 5. The display device according to claim 6 , wherein the display pixel is selected from the group consisting of a liquid crystal element, an electroluminescence element, an electrochromic element, and an electrophoretic element.

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