JP6647106B2 - Organic semiconductor materials and organic semiconductor devices - Google Patents

Description

  The present invention relates to an organic semiconductor material containing a specific nitrogen-containing conjugated alkenyl compound, a method for producing an organic semiconductor film using the organic semiconductor material, and an organic field effect transistor or the like obtained using the organic semiconductor material. The present invention relates to a semiconductor device.

  Generally, in a semiconductor element using silicon as an inorganic semiconductor material, a high-temperature process and a high-vacuum process are indispensable for forming a thin film. Since a high-temperature process is required, it is difficult to form a thin film of silicon on a plastic substrate or the like, and thus it has been difficult to impart flexibility and reduce the weight of a product incorporating a semiconductor element. In addition, since a high vacuum process is required, it has been difficult to increase the area and cost of a product incorporating a semiconductor element.

  Therefore, in recent years, studies have been made on organic semiconductor devices using organic semiconductor materials as organic electronic components, for example, organic electroluminescence (EL) elements, organic field effect transistor elements, organic CMOS circuits, organic thin film solar cells, and the like. These organic semiconductor materials can be formed on a plastic substrate or the like because the manufacturing process temperature can be significantly reduced as compared with an inorganic semiconductor material. Furthermore, by using an organic semiconductor material having high solubility in a solvent and having good film-forming properties, a coating method that does not require a vacuum process, for example, a thin film can be formed using an inkjet apparatus or the like, As a result, realization of a large area and low cost, which have been difficult in a semiconductor element using silicon as an inorganic semiconductor material, is expected. As described above, organic semiconductor materials are more advantageous than inorganic semiconductor materials in terms of larger area, flexibility, lighter weight, lower cost, and the like. Applications, for example, information tags, large-area sensors such as electronic artificial skin sheets and sheet-type scanners, and liquid crystal displays, displays such as electronic paper and organic EL panels are expected.

  The characteristics of the organic semiconductor material used for the organic semiconductor device, which is expected to be used in a wide range of applications described above, are exhibited by the movement of charges in the organic semiconductor material. Further, the electric charge is classified into two types according to the type of the moving electric charge. That is, a P-type organic semiconductor material in which positive holes move, and an N-type organic semiconductor material in which negative charges move. High charge mobility is required for both P-type organic semiconductor materials and N-type organic semiconductor materials. Another problem with organic semiconductor materials is that they exhibit stable semiconductor functions even in the air. In general, organic semiconductor materials interact with oxygen molecules and water molecules, such as positive charges (holes) and negative charges (electrons), which are transported in semiconductors. It had the problem of rapidly deteriorating.

  As countermeasures against this, improvement of atmospheric stability by controlling the highest occupied orbital energy level and lowest unoccupied orbital energy level of organic semiconductor materials, improvement of charge transfer characteristics by expanding the π-conjugate structure of semiconductor materials, and introduction of soluble functional groups Consideration has been given to imparting solvent solubility. As a result, polyacenes and heterocyclic aromatic derivatives have been developed as P-type semiconductor materials (Patent Document 1, Non-Patent Documents 1 and 2). In recent years, studies including a film forming process have been conducted for further increasing the mobility and stabilizing the driving.

  On the other hand, in the field of N-type organic semiconductor materials, although the aforementioned studies have been advanced, as materials applicable to the solution method, naphthalenetetracarboxylic acid diimide derivatives and fullerene (C60) derivatives have been focused on. No useful materials have been developed yet. For example, naphthalenetetracarboxylic diimide or fullerene itself has been reported to have high charge mobility, but is unstable in the atmosphere. Further, improvement in atmospheric stability by derivatization of naphthalenetetracarboxylic acid diimide or fullerene has been reported, but charge mobility has been reduced (Non-Patent Document 3).

In recent years, a cyanostyryl derivative has been developed as an N-type organic semiconductor material, and a device using the cyanostyryl derivative as a semiconductor has been reported to have a high electron mobility in the atmosphere (Non-Patent Document 4, Patent Document 4). 2).
Further, a nitrogen-containing cyanostyryl derivative has been synthesized and its molecular structure has been analyzed in detail, but no disclosure has been made on the semiconductor characteristics or effectiveness as a semiconductor device (Non-Patent Documents 5 and 6).

WO2003 / 016599 Patent No. 5553185

Org. Lett., Vol. 4, 15 (2002) J. Am. Chem. Soc., 129 (51), 15732 (2007) Chem. Rev., Vol. 107, 1066 (2007) J. Mater. Chem., 20, 6472 (2010) Chemical Papers 64 (3) 360-367 (2010) Chemical Papers 68 (2) 272-282 (2014)

  An object of the present invention is to provide an organic semiconductor material having high charge mobility and atmospheric stability and an organic semiconductor element using the same under the circumstances of the background art.

  The present inventors have conducted intensive studies and as a result, have found that a specific nitrogen-containing conjugated alkenyl compound has high charge mobility and atmospheric stability as an organic semiconductor material, and by using this for an organic semiconductor element, The present inventors have found that an organic semiconductor element having high characteristics can be obtained, and have reached the present invention.

The present invention is an organic semiconductor material comprising a compound represented by any of the following general formulas (1) to (3).

  Further, the present invention provides an organic semiconductor film containing the above organic semiconductor material. Further, the present invention is a method for producing an organic semiconductor film, which comprises applying a solution of the above organic semiconductor material in a specific organic solvent, followed by drying.

  Further, the present invention is an organic semiconductor device using the above organic semiconductor material. It is preferable that the organic semiconductor device is one of an organic field effect transistor (OFET) element, an organic complementary circuit element, and an organic photovoltaic element.

  The organic semiconductor material of the present invention has a structure in which a benzene ring is provided at the center and an alkenyl group is bonded to a pyridine ring at both ends, and an electron-withdrawing cyano group is introduced as a substituent of the alkenyl group. The π-electron orbit involved in the charge transfer spreads throughout the molecule, and without imparting a fluorine or trifluoromethyl group which is an electron-withdrawing group conventionally required to deepen the π-electron orbit, The energy level of the π-electron orbit can be deepened. Therefore, high charge transfer characteristics and atmospheric stability are exhibited. Therefore, since it is preferable as the organic semiconductor material of the present invention, an organic semiconductor device using the same can exhibit high characteristics. For example, application to organic field-effect transistors, organic thin-film solar cells, organic complementary circuits, information tags, large-area sensors such as electronic artificial skin sheets and sheet-type scanners, displays such as liquid crystal displays, electronic paper, and organic EL panels. The technical value is great.

FIG. 1 is a schematic cross-sectional view showing one example of the organic field effect transistor element of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the organic field effect transistor element of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the organic field effect transistor element of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the organic field effect transistor element of the present invention. 1 is a schematic cross-sectional view illustrating an example of the organic thin-film solar cell of the present invention. 1 is a schematic cross-sectional view showing another example of the organic thin-film solar cell of the present invention.

  The organic semiconductor material of the present invention contains a compound represented by any of the general formulas (1) to (3), and preferably contains at least 50 wt%, more preferably at least 90 wt% of the compound. It is good to contain. The component contained in the organic semiconductor material together with any of the compounds of the general formulas (1) to (3) is not particularly limited as long as the performance of the organic semiconductor material is not impaired. It is preferable that the organic semiconductor material is made of an organic compound.

  Next, an organic semiconductor device including an organic semiconductor film containing the organic semiconductor material of the present invention will be described with reference to FIGS. 1 to 4 taking an organic field effect transistor element (OFET element) as an example.

  FIGS. 1, 2, 3, and 4 illustrate embodiments of an OFET device to which the organic semiconductor material of the present invention can be applied, and are all schematic cross-sectional views showing the structure of the OFET device.

  The OFET device shown in FIG. 1 includes a gate electrode 2 on a surface of a substrate 1, an insulating film layer 3 formed on the gate electrode 2, and a source electrode 5 and a drain electrode 6 on the insulating film layer 3. And an organic semiconductor layer 4 is further formed.

  The OFET device shown in FIG. 2 includes a gate electrode 2 on a surface of a substrate 1, an insulating film layer 3 is formed on the gate electrode 2, and an organic semiconductor layer 4 is formed thereon. A source electrode 5 and a drain electrode 6 are provided on 4.

  In the OFET device shown in FIG. 3, a source electrode 5 and a drain electrode 6 are provided on the surface of a substrate 1, and a gate electrode 2 is formed on the outermost surface via an organic semiconductor layer 4 and an insulating film layer 3.

  In the OFET device shown in FIG. 4, an organic semiconductor layer 4, a source electrode 5, and a drain electrode 6 are provided on the surface of a substrate 1, and a gate electrode 2 is formed on the outermost surface via an insulating film layer 3.

  Examples of the material used for the substrate 1 include ceramic substrates such as glass, quartz, aluminum oxide, sapphire, silicon nitride, and silicon carbide; semiconductor substrates such as silicon, germanium, gallium boron, gallium phosphide, and gallium nitrogen; polyethylene terephthalate; Examples include resin substrates such as polyester such as polynaphthalene terephthalate, polyethylene, polypropylene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, cyclic polyolefin, polyimide, polyamide, and polystyrene. The thickness of the substrate can be from about 10 μm to about 2 mm, but is particularly preferably about 50 to about 100 μm for a flexible plastic substrate, and about 0 μm for a rigid substrate such as a glass plate or a silicon wafer. .1 to about 2 mm.

  The gate electrode 2 may be a metal thin film, a conductive polymer film, a conductive film made of a conductive ink or paste, or the like, or the substrate itself may be used as a gate electrode, such as heavily doped silicon. can do. Examples of gate electrode materials include aluminum, copper, stainless steel, gold, chromium, n-doped or p-doped silicon, indium tin oxide, and conductive polymers such as poly (3,4- Ethylenedioxythiophene), a conductive ink / paste containing carbon black / graphite, or a dispersion of colloidal silver in a polymer binder.

  The gate electrode 2 can be formed by using vacuum evaporation, sputtering of a metal or conductive metal oxide, spin coating of a conductive polymer solution or conductive ink, inkjet, spray, coating, casting, or the like. The thickness of the gate electrode 2 is preferably, for example, in the range of about 10 nm to 10 μm.

  The insulating film layer 3 can generally be an inorganic material film or an organic polymer film. Examples of suitable inorganic materials for the insulating film layer 3 include silicon oxide, silicon nitride, aluminum oxide, barium titanate, and barium zirconium titanate. Examples of organic compounds suitable as the insulating film layer 3 include polyesters, polycarbonates, poly (vinylphenol), polyimides, polystyrene, poly (methacrylate) s, poly (acrylates), polyvinylidene fluoride and CYTOP. There is a fluorine resin, an epoxy resin, or the like. Further, an inorganic material may be dispersed in an organic material and used as an insulating layer film, or an inorganic material and an organic material may be stacked and used. The thickness of the insulating film layer varies depending on the dielectric constant of the insulating material used, but is, for example, about 10 nm to 10 μm.

  Means for forming the insulating film layer include, for example, dry film forming methods such as vacuum evaporation, CVD, sputtering, and laser evaporation, spin coating, blade coating, screen printing, ink jet printing, and stamping. And the like, and can be used depending on the material.

  The source electrode 5 and the drain electrode 6 can be made of a material that provides a low-resistance ohmic contact to an organic semiconductor layer 4 described later. As a preferable material for the source electrode 5 and the drain electrode 6, those exemplified as preferable materials for the gate electrode 2 can be used, and examples thereof include gold, nickel, aluminum, platinum, a conductive polymer, and a conductive ink. The thickness of the source electrode 5 and the drain electrode 6 is typically, for example, about 40 nm to about 10 μm, and more preferably about 10 nm to 1 μm. For the purpose of reducing the charge transfer barrier between the source and drain electrodes and the organic semiconductor layer, the surfaces of the source and drain electrodes may be treated with a charge transfer barrier reducing material. As the charge transfer barrier reducing material, for example, 4-dimethylaminobenzenethiol can be used.

  Means for forming the source electrode 5 and the drain electrode 6 include, for example, a vacuum deposition method, a sputtering method, a coating method, a thermal transfer method, a printing method, a sol-gel method, and the like. During or after film formation, patterning is preferably performed as necessary. As a patterning method, for example, a photolithography method in which patterning and etching of a photoresist are combined and the like can be mentioned. In addition, patterning can be performed by using a printing method of inkjet printing, screen printing, offset printing, a soft lithography method such as a microcontact printing method, or a method combining a plurality of these methods.

  The organic semiconductor layer 4 uses a semiconductor material containing a compound represented by any of the general formulas (1) to (3). As a means for forming the organic semiconductor layer, for example, a vacuum deposition method, a CVD method, a sputtering method, a dry film formation method such as a laser deposition method, or after applying a solution or dispersion on a substrate, There is a wet film forming method of forming a thin film by removing the film.

  Since the compound represented by any of the general formulas (1) to (3) has excellent solubility in various organic solvents, a wet film formation method can be preferably applied. Examples of the wet film forming method include spin coating, drop coating, blade coating, screen printing, ink jet printing, stamping, die coating, capillary coating, and edge casting. For example, when the spin coating method is used, the organic semiconductor material of the present invention is dissolved in an appropriate solvent to prepare a solution having a concentration of 0.01 wt% to 10 wt%, and then the solution is formed on the insulating film layer 3 formed on the substrate 1. The organic semiconductor material solution is dropped, and then the treatment is performed at 500 to 6000 revolutions per minute for 5 to 120 seconds.

The solvent is selected depending on the solubility of the organic semiconductor material of the present invention in each solvent and the film quality after film formation. Examples of the solvent include water, alcohols represented by methanol, and aromatic hydrocarbons represented by toluene. , Aliphatic hydrocarbons such as hexane and cyclohexane, organic nitro compounds such as nitromethane and nitrobenzene, cyclic ether compounds such as tetrahydrofuran and dioxane, nitrile compounds such as acetonitrile and benzonitrile, and ketones such as acetone and methyl ethyl ketone And a solvent selected from aprotic polar solvents represented by dimethylsulfoxide, dimethylacetamide, sulfolane, N-methylpyrrolidone, dimethylimidazolidinone and the like. These solvents may be used in combination of two or more.
This is performed by processing at 500 to 6000 rotations for 5 to 120 seconds.

  Further, in these wet film forming methods, by forming a film while heating the substrate, the solubility of the organic semiconductor material of the present invention, the drying speed of the solvent, and the drying direction can also be controlled. The organic semiconductor layer preferably has a state in which charge transfer is easy, and is more preferably formed of an alignment film in which molecules are arranged in a certain direction. For this reason, the method for forming an organic semiconductor layer is more preferably a method for forming an alignment film. Specifically, the organic semiconductor material of the present invention is dissolved in an organic solvent having a boiling point of 50 ° C. or higher and has a concentration of 0.01%. A method of applying a solution of 10 wt% to 10 wt% on a substrate heated in a temperature range of 30 ° C. to 20 ° C. lower than the boiling point of the solvent, followed by drying.

  By the method described above, it is possible to produce an organic field effect transistor device using the organic semiconductor material of the present invention. In the obtained organic field-effect transistor device, the organic semiconductor layer forms a channel region, and on / off operation is performed by controlling the current flowing between the source electrode and the drain electrode by the voltage applied to the gate electrode. I do.

  Further, an element composed of a combination of a single organic field-effect transistor, such as an organic complementary transistor, is also included in the organic field-effect transistor of the present invention.

  Another preferred embodiment of the organic semiconductor device using the organic semiconductor material of the present invention is an organic photovoltaic element. Specifically, an organic photovoltaic device (organic thin-film solar cell) having a positive electrode, an organic semiconductor layer, and a negative electrode on a substrate, wherein the organic semiconductor layer includes the above-described organic semiconductor material of the present invention. It is.

  An example of the structure of an organic photovoltaic device to which the organic semiconductor material of the present invention can be applied will be described with reference to the drawings.

  FIG. 5 is a cross-sectional view showing a structural example of a general organic photovoltaic element used in the present invention, wherein 7 denotes a substrate, 8 denotes a positive electrode, 9 denotes an organic semiconductor layer, and 10 denotes a negative electrode. FIG. 6 is a cross-sectional view showing an example of a structure in which organic semiconductor layers are stacked, where 9-a is a P-type organic semiconductor layer and 9-b is an N-type organic semiconductor layer.

  The substrate is not particularly limited, and may have, for example, a conventionally known configuration. It is preferable to use a glass substrate or a transparent resin film having mechanical and thermal strength and transparency. Transparent resin films include polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, nylon, and polyetheretherketone. , Polysulfone, polyethersulfone, tetrafluoroethylene-perfluoroalkylvinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, Polyvinylidene fluoride, polyester, polycarbonate, polyurethane, polyimide, polyetherimide, polyimide, polypropylene and the like It is.

  As the electrode material, it is preferable to use a conductive material having a large work function for one electrode and a conductive material having a small work function for the other electrode. An electrode using a conductive material having a large work function becomes a positive electrode. Examples of the conductive material having a large work function include metals such as gold, platinum, chromium, and nickel, transparent metal oxides such as indium and tin, and composite metal oxides (indium tin oxide (ITO), indium Zinc oxide (IZO) or the like is preferably used. Here, the conductive material used for the positive electrode preferably has ohmic junction with the organic semiconductor layer. Further, when a hole transport layer described later is used, the conductive material used for the positive electrode preferably has an ohmic junction with the hole transport layer.

  An electrode using a conductive material having a small work function becomes a negative electrode. As the conductive material having a small work function, an alkali metal or an alkaline earth metal, specifically, lithium, magnesium, or calcium is used. Further, tin, silver and aluminum are also preferably used. Further, an electrode made of an alloy made of the above metal or a laminate of the above metal is also preferably used. In addition, by introducing a metal fluoride such as lithium fluoride or cesium fluoride into the interface between the negative electrode and the electron transport layer, it is possible to improve the extraction current. Here, the conductive material used for the negative electrode preferably has ohmic junction with the organic semiconductor layer. Further, when an electron transport layer described later is used, it is preferable that the conductive material used for the negative electrode has ohmic contact with the electron transport layer.

  The organic semiconductor layer contains the organic semiconductor material of the present invention. That is, an organic semiconductor material containing a compound represented by any of formulas (1) to (3) is used. The organic semiconductor material of the present invention is used as a P-type organic semiconductor material (hereinafter also referred to as a P-type organic material), an N-type organic semiconductor material (hereinafter also referred to as an N-type organic material), or both. For example, two or more compounds represented by any of the general formulas (1) to (3) are used, and one or more of the compounds is a P-type organic material component, and the other one or more is an N-type organic material component. can do. Further, the compound represented by any of the general formulas (1) to (3) can be contained as an organic semiconductor material component in only one of the P-type organic material and the N-type organic material.

  The organic semiconductor material containing the compounds represented by the formulas (1) to (3) functions as a P-type organic material or an N-type organic material, but is preferably used as an N-type organic semiconductor material.

  The organic semiconductor layer is formed including at least one organic semiconductor material including a compound represented by any of formulas (1) to (3), and includes, for example, an organic semiconductor material represented by formula (1). It is composed of an N-type organic material and a known or new P-type organic material.

  In the case of the organic photovoltaic device having the structure shown in FIG. 5, the P-type organic material and the N-type organic material are preferably mixed, and the P-type organic material and the N-type organic material are compatible at the molecular level. Or phase-separated. Although the domain size of the phase separation structure is not particularly limited, it is usually 1 nm or more and 50 nm or less. Further, in the case of the organic photovoltaic element in which the P-type organic material and the N-type organic material of the structural example shown in FIG. 6 are laminated, the layer having the P-type organic material is on the positive electrode side, It is preferably on the negative electrode side. The thickness of the organic semiconductor layer is preferably from 5 nm to 500 nm, more preferably from 30 nm to 300 nm. When the semiconductor material of the present invention is used for an N-type organic material, the layer having the N-type organic material preferably has a thickness of 1 nm to 400 nm among the above thicknesses, More preferably, it is 15 nm to 150 nm.

  Examples of the P-type organic material include polythiophene polymers, benzothiadiazole-thiophene derivatives, benzothiadiazole-thiophene copolymers, poly-p-phenylenevinylene polymers, poly-p-phenylene polymers, and polyfluorenes. Polymers, polypyrrole polymers, polyaniline polymers, polyacetylene polymers, conjugated polymers such as polythienylenevinylene polymers, H2 phthalocyanine (H2Pc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc) ), Porphyrin derivatives, N, N′-diphenyl-N, N′-di (3-methylphenyl) -4,4′-diphenyl-1,1′-diamine (TPD), N, N ′ -Dinaphthyl-N, N'-diphenyl-4,4'-diphenyl-1,1'- Triarylamine derivatives such as amine (NPD), carbazole derivatives such as 4,4′-di (carbazol-9-yl) biphenyl (CBP), oligothiophene derivatives (terthiophene, quarterthiophene, sexithiophene, octithiophene, etc.) ).

  As the N-type organic material, an organic semiconductor material containing a compound represented by any of the formulas (1) to (3) may be used alone, or another N-type organic material may be used as a mixture. . As other N-type organic materials, for example, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), 3,4 9,10-perylenetetracarboxylic bisbenzimidazole (PTCBI), N, N′-dioctyl-3,4,9,10-naphthyltetracarboxydiimide (PTCDI-C8H), 2- (4-biphenylyl) -5 Oxazole derivatives such as (4-t-butylphenyl) -1,3,4-oxadiazole (PBD) and 2,5-di (1-naphthyl) -1,3,4-oxadiazole (BND); 3- (4-biphenylyl) -4-phenyl-5- (4-t-butylphenyl) -1,2,4-triazole (T AZ) and other unsubstituted ones including triazole derivatives, phenanthroline derivatives, phosphine oxide derivatives, fullerene compounds (C60, C70, C76, C78, C82, C84, C90, C94) and [6,6] -phenyl C61 Butyric acid methyl ester ([6,6] -PCBM), [5,6] -phenyl C61 Butyric acid methyl ester ([5,6] -PCBM), [6,6] -phenyl C61 Butyric acid hexyl Ester ([6,6] -PCBH), [6,6] -phenyl C61 butyric acid dodecyl ester ([6,6] -PCBD), phenyl C71 butyric acid methyl ester (PC70BM), phenyl C85 butyric acid Methyl ester (PC84BM) Etc.), carbon nanotubes (CNT), and poly -p- phenylene vinylene-based polymer derivatives obtained by introducing cyano group into (CN-PPV) and the like.

  In the organic photovoltaic device of the present invention, a hole transport layer may be provided between the positive electrode and the organic semiconductor layer. Examples of the material for forming the hole transport layer include conductive polymers such as polythiophene polymers, poly-p-phenylenevinylene polymers, and polyfluorene polymers, phthalocyanine derivatives (H2Pc, CuPc, ZnPc, etc.), Low molecular organic compounds exhibiting P-type semiconductor properties, such as porphyrin derivatives, are preferably used. In particular, a polythiophene-based polymer such as polyethylene dioxythiophene (PEDOT) or PEDOT obtained by adding polystyrene sulfonate (PSS) is preferably used. The hole transport layer preferably has a thickness of 5 nm to 600 nm, more preferably 30 nm to 200 nm.

  In the organic photovoltaic device of the present invention, an electron transport layer may be provided between the organic semiconductor layer and the negative electrode. The material for forming the electron transport layer is not particularly limited, but may be the above-mentioned N-type organic material (NTCDA, PTCDA, PTCDI-C8H, oxazole derivative, triazole derivative, phenanthroline derivative, phosphine oxide derivative, fullerene compound, CNT , CN-PPV, etc.) are preferably used. The electron transport layer preferably has a thickness of 5 nm to 600 nm, more preferably 30 nm to 200 nm.

  Further, in the organic photovoltaic device of the present invention, two or more organic semiconductor layers may be stacked (tandemly formed) via one or more intermediate electrodes to form a series junction. For example, a laminated structure of substrate / positive electrode / first organic semiconductor layer / intermediate electrode / second organic semiconductor layer / negative electrode can be given. By stacking in this way, the open-circuit voltage can be improved. Note that the above-described hole transport layer may be provided between the positive electrode and the first organic semiconductor layer and between the intermediate electrode and the second organic semiconductor layer, and may be provided between the first organic semiconductor layer and the intermediate electrode. The above-described hole transport layer may be provided between the second organic semiconductor layer and the negative electrode.

  For the formation of the organic semiconductor layer, any of spin coating, blade coating, slit die coating, screen printing, bar coater coating, mold coating, print transfer, immersion pull-up, ink jet, spray, vacuum deposition, etc. The formation method may be selected according to the characteristics of the organic semiconductor layer to be obtained, such as film thickness control and orientation control, but when the organic semiconductor material of the present invention is used, spin coating may be used. Wet film forming methods such as blade coat coating, slit die coat coating, screen printing coating, bar coater coating, mold coating, print transfer method, immersion pull-up method, ink jet method, and spray method can be preferably applied.

  The organic semiconductor device of the present invention uses the organic semiconductor material of the present invention. The organic semiconductor device is preferably an organic field effect transistor or an organic photovoltaic element.

窒素雰囲気下の５０ｍｌフラスコに３−ピリジンアセトニトリル４７３ｍｇ（４ｍｍｏｌ）、テレフタルアルデヒド２６８ｍｇ（２ｍｍｏｌ）、エタノール５ｍｌ、ＤＭＦ１５ｍｌを入れて溶液とし、これにナトリウムエトキシド１４ｍｇ（０．２ｍｍｏｌ）をエタノール１ｍｌに溶かした溶液を室温下マグネチックスターラーで撹拌しながら滴下した。滴下後、さらに２時間撹拌を行ったのち、メタノールを加え結晶を吸引ろ過した。得られた結晶をメタノールでよく洗浄してからデシケーター中で真空乾燥して粗生成物を得た。得られた粗生成物を、クロロホルムから再結晶することで黄色結晶の化合物（２）を得た。収量５３５ｍｇ(収率８０％)、Ｍａｓｓ（ＦＡＢ^＋）ｍ／ｚ＝３３４(Ｍ^＋)であった。 Synthesis Example 1
"Synthesis of Compound (2)"

In a 50 ml flask under a nitrogen atmosphere, 473 mg (4 mmol) of 3-pyridineacetonitrile, 268 mg (2 mmol) of terephthalaldehyde, 5 ml of ethanol, and 15 ml of DMF were put into a solution, and 14 mg (0.2 mmol) of sodium ethoxide was dissolved in 1 ml of ethanol. The solution was added dropwise with stirring with a magnetic stirrer at room temperature. After the dropwise addition, the mixture was further stirred for 2 hours, methanol was added, and the crystals were filtered by suction. The obtained crystals were thoroughly washed with methanol and then dried in a desiccator under vacuum to obtain a crude product. The obtained crude product was recrystallized from chloroform to obtain a yellow crystalline compound (2). The yield was 535 mg (80% yield), and Mass (FAB ⁺ ) m / z was 334 (M ⁺ ).

Synthesis Examples 2 and 3
Compound (1) and compound (3) were obtained in the same manner as in Synthesis Example 1 above.

Example 1
"Organic transistor element fabrication"
The characteristics of the organic semiconductor material of the present invention were evaluated by preparing an organic field effect transistor having the configuration shown in FIG. First, a 300-nm-thick silicon wafer with a thermal oxide film (n-doped) was used as a gate electrode and a gate insulating film, and CYTOP was spin-coated on the oxide film surface at 3000 rpm for 120 seconds. The compound (2) is formed on the surface of this film by a vacuum evaporation method (evaporation conditions: reduced pressure of about 4.0 × 10 ⁻⁶ torr) under the condition that the film thickness becomes about 50 nm to form an organic semiconductor layer. did. Further, a source electrode and a drain electrode each having a thickness of about 50 nm and made of Au were formed on the surface of the organic semiconductor layer by a vacuum evaporation method using a shadow mask by a vacuum evaporation method, to produce an organic field effect transistor. The channel length (L) of the formed source electrode and drain electrode was 20 μm, and the channel width (W) was 2 mm.・

"Evaluation"
A voltage of 100 V is applied between the source and drain electrodes of the obtained organic thin film transistor, and the gate voltage is changed in a range of −20 V to 100 V under vacuum (10 ⁻⁵ torr or less). Characteristics and transfer characteristics were evaluated. As a result, an electron mobility of 1.0 × 10 ⁻¹ cm ² · Vs was obtained in the measurement after the device was prepared.

Example 2
An organic field effect transistor was manufactured in the same manner as in Example 1, except that the compound (1) was used instead of the compound (2). When the transistor characteristics of the obtained device were evaluated in the same manner as in Example 1, an electron mobility of 0.8 × 10 ^-1 cm ² · Vs was obtained.

Example 3
An organic field effect transistor was manufactured in the same manner as in Example 1, except that the compound (3) was used instead of the compound (2). When the transistor characteristics of the obtained device were evaluated in the same manner as in Example 1, an electron mobility of 0.9 × 10 ⁻¹ cm ² · Vs was obtained.

Example 4
An organic field effect transistor having the configuration shown in FIG. 2 in which an organic semiconductor layer was formed by wet film formation was prepared and evaluated. A silicon wafer (n-doped) having a thermally grown silicon oxide layer having a thickness of about 300 nm was washed with a sulfuric acid-hydrogen peroxide aqueous solution, boiled with isopropyl alcohol, and dried. The obtained silicon wafer (n-doped) having the thermally grown silicon oxide layer is heated to 80 ° C. on a hot plate, and 0.5 wt% of a chlorobenzene (boiling point: 132 ° C.) solution of compound (2) is dropped thereon. Then, the organic semiconductor layer was formed by drying the solvent. The formation of the source electrode and the drain electrode was performed in the same manner as in Example 1, and an organic field effect transistor was manufactured. When the transistor characteristics of the obtained device were evaluated in the same manner as in Example 1, an electron mobility of 1.5 × 10 ⁻¹ cm ² · Vs was obtained.

Example 5
The organic thin film transistor element for which the transistor characteristics were evaluated in Example 4 was exposed to the air and the characteristics were evaluated in the air. As a result, an electron mobility of 1.2 × 10 ⁻¹ cm ² · Vs was obtained.

得られた素子を実施例２と同様にトランジスタ特性を評価したところ、電界効果による電流上昇が観測されなかった。そのため、電子移動度を測定できなかった。 Comparative Example 1
An organic field effect transistor was manufactured in the same manner as in Example 1, except that the comparative compound (1) was used instead of the compound (2).

When the transistor characteristics of the obtained device were evaluated in the same manner as in Example 2, no increase in current due to the field effect was observed. Therefore, the electron mobility could not be measured.

  Comparison between Examples 1 to 5 and Comparative Example 1 revealed that the organic field-effect transistor using the organic semiconductor material of the present invention has high characteristics and can be driven stably even in air.

DESCRIPTION OF SYMBOLS 1 Substrate for organic field effect transistors 2 Gate electrode, 3 insulating layers 4 Organic semiconductor 5 Source electrode, 6 Drain electrode 7 Substrate for organic photovoltaic elements 8 Positive electrode 9 Organic semiconductor layer 9-a Electron donating organic semiconductor layer, 9- b Electron accepting organic semiconductor layer 10 Negative electrode

Claims (6)

An organic semiconductor material comprising a compound represented by any one of the following general formulas (1) to (3).

  An organic semiconductor film comprising the organic semiconductor material according to claim 1.   The semiconductor material according to claim 1 is dissolved in an organic solvent having a boiling point of 50 ° C or higher to form a solution having a concentration of 0.01 to 10% by weight, which is in a temperature range of 30 ° C to 20 ° C or lower than the boiling point of the solvent. A method for producing an organic semiconductor film, comprising applying the composition to a heated substrate and drying the solvent.   An organic semiconductor device using the organic semiconductor film according to claim 2.   An organic thin film transistor using the organic semiconductor film according to claim 2 for a semiconductor layer. An organic photovoltaic device, wherein the organic semiconductor film according to claim 2 is used for a semiconductor layer.

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