JP6592758B2 - Novel condensed polycyclic aromatic compounds and uses thereof - Google Patents

Description

  The present invention relates to novel condensed polycyclic aromatic compounds and uses thereof (organic semiconductor materials using condensed polycyclic aromatic compounds, organic semiconductors using condensed polycyclic aromatic compounds and methods for forming the same, and condensed polycyclic aromatic compounds. More specifically, the present invention relates to a condensed polycyclic aromatic compound that can function as an organic semiconductor suitable for printed electronics and its use.

  Conventionally, a condensed polycyclic aromatic compound having a [1] benzothieno [3,2-b] [1] benzothiophene (hereinafter abbreviated as “BTBT” as appropriate) skeleton as an organic semiconductor compound exhibiting high carrier mobility It has been known.

  For example, Patent Document 1 describes, as an organic semiconductor material, a condensed polycyclic aromatic compound in which an unsubstituted or halogeno-substituted C1-C36 aliphatic hydrocarbon group is independently introduced at positions 2 and 7 with respect to the BTBT skeleton. Has been. Patent Document 1 discloses that the above compound is dissolved in an organic solvent and has a practical printability, and that a field effect transistor using the above compound has semiconductor characteristics such as excellent carrier mobility and is stable. It is described that it is excellent.

  Further, Patent Document 2 discloses a condensed polymer such as 2-decyl-7-phenyl BTBT, 2-decyl-7-p-tolyl BTBT, 2-decyl-7-o-tolyl BTBT as an organic semiconductor exhibiting liquid crystallinity. A ring aromatic compound is described (Patent Document 2, paragraphs [0274] [0323] [0327]). Further, Patent Document 2 describes that a transistor manufactured using these materials exhibits high electron mobility (paragraphs [0022] [0383] of Patent Document 2).

  Non-Patent Documents 1 and 2 describe that “a molecular fastener that can control the distance between π-electron molecular skeletons to some extent by intermolecular interaction by alkyl chains when a specific π-electron molecular skeleton is substituted with an alkyl chain of a specific length. "Effect".

International Publication No. 2008/047896 International Publication No. 2012/121393

H. Inokuchi et al., "A novel type of organic semiconductors. Molecular fastener effect", Chemistry Letters, 1986, p.1263-1266 S. Ukai et al. "Molecular-fastener effects on transport property of TTCn-TTF field-effect transistors", Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2006, Vol.284-285, p.589-593

  In recent years, the construction of organic semiconductor devices (printed electronics) by thinning organic semiconductors using printing technology has become important in terms of forming high-quality organic semiconductor thin films and improving process efficiency.

  For the construction of organic semiconductor devices by thinning organic semiconductors using printing technology, organic semiconductor compounds have good solubility (eg chloroform) to form organic semiconductor solutions (inks) used in printing technology. The solubility in the aqueous solution is required to be 3.5 mg / mL or more. If the solubility of the organic semiconductor compound is not good, an organic semiconductor solution (ink) cannot be formed, and an organic semiconductor thin film having an appropriate thickness cannot be formed.

  In addition, due to the stability of organic semiconductor devices and process tolerance in device manufacturing, organic semiconductor compounds may have excellent thermal stability (for example, characteristics will not deteriorate even when heated at 150 ° C. for 30 minutes). Required.

  Therefore, an organic semiconductor compound having excellent thermal stability and good solubility is desired.

  However, the condensed polycyclic aromatic compounds having a BTBT skeleton described in Patent Documents 1 and 2 are not so high in thermal stability and do not have excellent thermal stability and good solubility.

  The present invention has been made in view of the above-described conventional problems, and its purpose is a condensed polycyclic aromatic compound having excellent thermal stability and good solubility, an organic semiconductor material using the compound, and the compound It aims at providing organic semiconductor devices, such as an organic thin-film transistor using the compound, its formation method, and an organic thin-film transistor using the compound.

  In order to solve the above problems, the condensed polycyclic aromatic compound of the present invention has the following general formula (1).

(In the formula, ^one of R ¹ and R ² represents an aryl group, the other represents a hydrogen atom, R ³ and R ⁴ represent one alkyl group having 1 to 4 carbon atoms, the other represents a hydrogen atom, and X ¹ And X ² each independently represents a sulfur atom, a selenium atom, or a tellurium atom)
It is characterized by being expressed.

  According to the above configuration, by reducing the number of carbon atoms of the alkyl group to 4 or less, it is possible to reduce the interaction between alkyl chains between molecules and the interaction between BTBT skeletons. The cohesive force can be reduced. As a result, a condensed polycyclic aromatic compound having excellent thermal stability and good solubility can be realized. In addition, since the condensed polycyclic aromatic compound has excellent thermal stability, an organic semiconductor thin film or an organic semiconductor device having excellent thermal stability can be constructed using the condensed polycyclic aromatic compound. In addition, since the condensed polycyclic aromatic compound has good solubility, an organic semiconductor solution (ink) having a concentration suitable for use in a method for forming an organic semiconductor thin film by coating or printing can be easily prepared. The organic semiconductor thin film can be formed with high homogeneity by the method for forming the organic semiconductor thin film.

  According to the present invention, a condensed polycyclic aromatic compound having excellent thermal stability and good solubility, an organic semiconductor material using the compound, an organic semiconductor thin film using the compound, a formation method thereof, and the An organic semiconductor device such as an organic thin film transistor using the compound can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows some examples of the organic thin-film transistor of this invention, (a) is a schematic sectional drawing which shows the example of an aspect of a bottom gate-bottom contact type organic thin-film transistor, (b) is a bottom gate-top. It is a schematic sectional drawing which shows the example of an aspect of a contact type organic thin-film transistor, (c) is a schematic sectional drawing which shows the example of an aspect of a top gate-top contact type organic thin-film transistor, (d) is a bottom gate-top & bottom contact type It is a schematic sectional drawing which shows the example of an aspect of an organic thin-film transistor, (e) is a schematic sectional drawing which shows the example of an aspect of an electrostatic induction transistor, (f) is a cross section which shows the example of an aspect of a top gate-bottom contact type organic thin-film transistor FIG. It is explanatory drawing for demonstrating the manufacturing method of the bottom-gate top contact type organic thin-film transistor as one example of the organic thin-film transistor of this invention, (a)-(f) is a schematic cross section which shows each process of the said manufacturing method FIG. It is a schematic sectional drawing which shows an example of the structure of the organic solar cell device as one aspect | mode of the organic-semiconductor device of this invention. It is a figure which shows the crystal structure of the condensed polycyclic aromatic compound obtained in Example 1 and Comparative Examples 1, 3, and 5. It is a figure which shows the crystal structure of the condensed polycyclic aromatic compound obtained in Example 1, 2 and Comparative Example 1, 3, 5, 6. 4 is a diagram showing a differential heat / thermogravimetric change curve of the condensed polycyclic aromatic compound obtained in Example 4. FIG. It is a figure which shows the differential scanning calorific value curve of the condensed polycyclic aromatic compound obtained in Examples 1-3 and Comparative Example 1. It is a figure which shows the differential scanning calorific value curve of the condensed polycyclic aromatic compound obtained by Comparative Examples 2-6. It is a figure which shows the differential scanning calorific value curve of the condensed polycyclic aromatic compound obtained in Examples 5-8. 10 is a graph showing semiconductor characteristics of the organic thin film transistor obtained in Example 9.

  Hereinafter, the present invention will be described in detail.

[Condensed polycyclic aromatic compound]
The condensed polycyclic aromatic compound of the present invention has the following general formula (1):

(In the formula, ^one of R ¹ and R ² represents an aryl group, the other represents a hydrogen atom, R ³ and R ⁴ represent one alkyl group having 1 to 4 carbon atoms, the other represents a hydrogen atom, and X ¹ And X ² each independently represents a sulfur atom, a selenium atom, or a tellurium atom)
It is a condensed polycyclic aromatic compound represented by these.

[1] Benzochalcogeno [3,2-b] [1] Aryl group on benzochalcogenophene skeleton because of easy synthesis among the condensed polycyclic aromatic compounds represented by general formula (1) A compound in which the substitution position of and the substitution position of the alkyl group are symmetrical, that is, in general formula (1), R ¹ is an aryl group, R ² is a hydrogen atom, R ³ is an alkyl group having 1 to 4 carbon atoms, R ⁴ Is a compound in which R ¹ is a hydrogen atom, or a compound in which R ¹ is a hydrogen atom, R ² is an aryl group, R ³ is a hydrogen atom, and R ⁴ is an alkyl group having 1 to ⁴ carbon atoms in the general formula (1), Among these compounds, R ¹ is an aryl group, R ² is a hydrogen atom, R ³ is an alkyl group having 1 to 4 carbon atoms, and R ⁴ is a hydrogen atom because of higher thermal stability. Certain compounds are most preferred.

  The alkyl group having 1 to 4 carbon atoms may be a linear alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, n-propyl group, n-butyl group), or 3 to 4 carbon atoms. It may be a branched alkyl group (isopropyl group, isobutyl group, sec-butyl group, t-butyl group). The alkyl group is preferably an alkyl group having 2 to 4 carbon atoms because the thermal stability and solubility of the condensed polycyclic aromatic compound are further increased.

  The aryl group is an aromatic hydrocarbon group that may have a substituent. In the aryl group, the solubility of the condensed polycyclic aromatic compound becomes higher as the number of carbons constituting the aromatic ring is smaller. Therefore, the aryl group having 6 to 14 carbons constituting the aromatic ring (for example, Substituted or unsubstituted phenyl group, substituted or unsubstituted 1-naphthyl group, substituted or unsubstituted 2-naphthyl group, substituted or unsubstituted biphenyl group, substituted or unsubstituted anthranyl group). Preferably, an aryl group having 6 to 10 carbon atoms constituting the aromatic ring (for example, a substituted or unsubstituted phenyl group, a substituted or unsubstituted 1-naphthyl group, a substituted or unsubstituted 2-naphthyl group, etc.) Is more preferable, and a phenyl group is most preferable. The substituent on the aromatic ring is preferably an alkyl group, and if the alkyl group has too many carbon atoms, the thermal stability may be reduced. Particularly preferred is an alkyl group of 2.

  Specific examples of the compound represented by the general formula (1) are shown in Tables 1 and 2 below.

  The condensed polycyclic aromatic compound is preferably a compound in which a peak showing a phase transition below 170 ° C. is not observed in the differential scanning calorimetry curve, and a peak showing a phase transition below 200 ° C. is not observed in the differential scanning calorimetry curve. It is more preferable that the compound be a compound, whereby a condensed polycyclic aromatic compound having higher thermal stability, an organic semiconductor thin film and an organic semiconductor device using the same can be realized.

  The condensed polycyclic aromatic compound preferably does not exhibit liquid crystallinity. Thereby, a condensed polycyclic aromatic compound with higher thermal stability, an organic semiconductor thin film and an organic semiconductor device using the same can be realized.

  The condensed polycyclic aromatic compound preferably has a sufficiently high solubility in an organic solvent. Specifically, the solubility in chloroform is preferably 3.5 mg / mL or more, and the solubility in chloroform is 5 mg / mL. More preferably, it is mL or more. Thereby, it is possible to realize a condensed polycyclic aromatic compound that has higher solubility in an organic solvent and can easily form a thin film having an appropriate film thickness by coating or printing. Since the solubility of the condensed polycyclic aromatic compound in an organic solvent is preferably as high as possible, there is no particular upper limit. However, for condensed polycyclic aromatic compounds with very high solubility in organic solvents, when an organic semiconductor thin film is formed by applying or printing a solution dissolved in an organic solvent, the condensed polycyclic aromatic compound is dissolved to the limit of dissolution. If the compound is dissolved, the concentration of the condensed polycyclic aromatic compound in the solution may become too high, making it difficult to form a highly homogeneous organic semiconductor thin film. What is necessary is just to set the density | concentration of a compound suitably.

In the condensed polycyclic aromatic compound represented by the general formula (1), for example, R ¹ is an aryl group (Ar), R ³ is an alkyl group having 1 to 4 carbon atoms, and R ² and R ⁴ are In the case of a hydrogen atom, for example, as shown in Scheme 1 below, bromination is performed using the corresponding 2-alkyl [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene as a raw material. After obtaining the corresponding 2-alkyl-7-bromo [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene, it can be synthesized by performing a coupling reaction with arylboronic acid.

(In the above scheme, R ⁵ represents an alkyl group having 1 to 4 carbon atoms)
For example, in the case of 2-alkyl [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene that is a starting material of the above-described scheme 1, R ⁵ is —CH ₂ R ⁶ (where R ⁶ has 1 to 3 carbon atoms). For example, as shown in Scheme 2 below, [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene is used as a starting material. Then, the Friedel-Crafts reaction is carried out to obtain 2-alkylcarbonyl [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene, which is then reduced.

In addition, 2-alkyl [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene, which is the starting material of Scheme 1 above, can be represented by the following scheme 3 when R ⁵ is a methyl group, for example. As shown, bromination was performed using [1] benzochalcogeno [3,2-b] [1] benzochalcogenophene as a starting material to give 2-bromo [1] benzochalcogeno [3,2-b] [1]. After obtaining benzochalcogenophene, it can be synthesized by subjecting this compound to a coupling reaction with methylboronic acid.

[Organic semiconductor thin film and method for forming the same, and organic semiconductor material used therefor]
The organic semiconductor thin film of this invention contains the condensed polycyclic aromatic compound represented by General formula (1).

  The thickness of the organic semiconductor thin film of the present invention varies depending on its use and is not particularly limited, but is usually 0.1 nm to 10 μm, preferably 0.5 nm to 3 μm, more preferably 1 nm to 1 μm.

  Various methods can be used as the method of forming the organic semiconductor thin film of the present invention. In general, the method for forming the organic semiconductor thin film is roughly classified into a formation method by a vacuum process and a formation method by a solution process, and any of them may be used. Examples of the method for forming an organic semiconductor thin film by the vacuum process include resistance heating vapor deposition, electron beam vapor deposition, sputtering, molecular lamination, CVD, molecular beam epitaxial growth, and vacuum vapor deposition. In addition, as a method for forming an organic semiconductor thin film by a solution process, a spin coating method, a drop casting method, a dip coating method, a spray method, a die coater method, a roll coater method, a bar coater method, etc .; flexographic printing, resin letterpress Topographic printing methods such as printing; flat plate printing methods such as offset printing methods, dry offset printing methods and pad printing methods; intaglio printing methods such as gravure printing methods; stencil printing such as silk screen printing methods, photocopier printing methods and lithographic printing methods Method; inkjet printing method; microcontact printing method and the like. The organic semiconductor thin film can be formed by the above-described one forming method, or can be formed by combining a plurality of the above-described forming methods. Hereinafter, a method for forming an organic semiconductor thin film will be described in detail.

  As an organic semiconductor thin film forming method of the present invention, an organic semiconductor thin film is formed from an organic semiconductor material containing at least one condensed polycyclic aromatic compound represented by the general formula (1) and an organic solvent. A method of removing the organic solvent after coating or printing on the surface to be coated (hereinafter referred to as “attached surface”) is preferable.

  The organic semiconductor material of this invention is used suitably for the said method, and contains the condensed polycyclic aromatic compound represented by General formula (1), and the organic solvent. The organic semiconductor material of the present invention can be prepared by dissolving or dispersing the condensed polycyclic aromatic compound represented by the general formula (1) in an organic solvent.

  The organic solvent used for the organic semiconductor material is not particularly limited as long as the organic semiconductor thin film containing the condensed polycyclic aromatic compound can be formed on the deposition surface. Specific examples of the organic solvent include halogenated hydrocarbon solvents such as dichloromethane, chloroform, dichloroethane, chlorobenzene, dichlorobenzene, and chloronaphthalene; ether solvents such as diethyl ether, anisole, ethoxybenzene, and tetrahydrofuran; dimethylacetamide Amide solvents such as dimethylformamide and N-methylpyrrolidone; Nitrile solvents such as acetonitrile, propionitrile and benzonitrile; Alcohol solvents such as methanol, ethanol, isopropanol, butanol and cyclohexanol; Octafluoropentanol and penta Fluorinated alcohol solvents such as fluoropropanol; ester solvents such as ethyl acetate, butyl acetate, ethyl benzoate, diethyl carbonate; benzene, toluene, Ren, mesitylene, ethylbenzene, tetrahydronaphthalene, aromatic hydrocarbon solvents such as phenyl cyclohexane; hexane, cyclohexane, octane, decane, hydrocarbon solvents such as decahydronaphthalene and the like. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The content of the condensed polycyclic aromatic compound represented by the general formula (1) in the organic semiconductor material varies depending on the type of the organic solvent and the thickness of the organic semiconductor thin film to be prepared, and it is difficult to determine it in general. As a guideline, it is preferably within a range of 0.001% by weight to 20% by weight and more preferably within a range of 0.01% by weight to 10% by weight with respect to the total amount of the organic semiconductor material. preferable. The organic semiconductor material of the present invention may be dissolved or dispersed in the above organic solvent, but is preferably dissolved as a uniform solution.

  The said organic-semiconductor material can contain other organic semiconductors and various additives other than the condensed polycyclic aromatic compound represented by General formula (1) as needed.

  Examples of the additive include a semiconducting polymer compound exhibiting semiconductivity and an insulating polymer compound exhibiting insulation. Specific examples of the semiconducting polymer compound include polyacetylene polymer, polydiacetylene polymer, polyparaphenylene polymer, polyaniline polymer, polythiophene polymer, polyarylamine polymer, polypyrrole polymer. , Polythienylene vinylene polymer, polyaniline polymer, polyazulene polymer, polypyrene polymer, polycarbazole polymer, polyselenophene polymer, polyfuran polymer, poly (p-phenylene) polymer high Examples thereof include molecules, polyindole polymers, polypyridazine polymers, polysulfides polymers, polyparaphenylene vinylene polymers, polyethylenedioxythiophene polymers, nucleic acids, and derivatives thereof.

  On the other hand, specific examples of the insulating polymer material include acrylic polymer, polyethylene polymer, polymethacrylate polymer, polystyrene polymer, polyethylene terephthalate polymer, nylon polymer, polyamide polymer. Polyester polymer, vinylon polymer, polyisoprene polymer, cellulose polymer, copolymer polymer, and derivatives thereof.

  If a polymer material such as a semiconductor polymer compound or an insulating polymer compound is used, the amount of the polymer material used when the total amount of the organic semiconductor material is 1 is usually 0.5% to 95%. %, Preferably 1% to 90%, more preferably 3% to 75%, and most preferably 5% to 50%. It is not necessary to use a polymer material.

  In addition, the organic semiconductor material has other additives such as a carrier generator (dopant), a conductive substance, a viscosity modifier, a surface tension modifier, a leveling agent, a penetrant, as long as the obtained effect is not impaired. Wetting preparation agents, rheology modifiers and the like may be added. When the above other additives are added, the amount of the above other additives is usually 0.01 to 10% by weight, preferably 0.05 to 5 when the total amount of the organic semiconductor material is 1. % By weight, more preferably 0.1 to 3% by weight.

  The organic semiconductor material of the present invention may contain other additives. However, even if it does not contain, the effect of the present invention can be obtained.

  In the formation method using the above coating or printing, the environment such as the temperature of the adherend (an object to form the organic semiconductor thin film on the surface) and the organic semiconductor material during the formation of the organic semiconductor thin film is also important. Depending on the temperature of the adherend and the organic semiconductor material, the characteristics of the organic semiconductor thin film change (when the organic semiconductor thin film is used in an organic semiconductor device described later, the characteristics of the organic semiconductor device change). It is preferred to carefully select the temperature of the deposit and the organic semiconductor material during the formation of. The temperature of the adherend and the organic semiconductor material is usually 0 to 200 ° C, preferably 10 to 120 ° C, more preferably 15 to 100 ° C. Care must be taken because the temperature of the organic semiconductor material largely depends on the type of the organic solvent contained in the organic semiconductor material.

  The thickness of the organic semiconductor thin film formed by the forming method using the above coating or printing is usually 0.1 nm to 10 μm, preferably 0.5 nm to 3 μm, and more preferably 1 nm to 1 μm.

  Next, as a method for forming an organic semiconductor thin film similar to the method using coating or printing described above, the condensed polycyclic aromatic compound represented by the general formula (1) is obtained by dropping the organic semiconductor material onto the water surface. A Langmuir project method in which a monomolecular film of an organic semiconductor thin film is prepared, and the monomolecular film is transferred to a deposition surface and laminated; a liquid crystal state or a melt containing a condensed polycyclic aromatic compound represented by the general formula (1) For example, a method of introducing the organic semiconductor thin film forming material in a state between the substrates by capillary action may be employed.

  Furthermore, as another method for forming an organic semiconductor thin film, a method for forming an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1) by the vacuum process described above will be described.

As this method, the organic semiconductor thin film forming material containing the condensed polycyclic aromatic compound is evaporated by heating under vacuum in a vessel such as a crucible or a metal boat, and the evaporated organic semiconductor thin film forming material A method of adhering (depositing) to the adherend surface of the adherend, that is, a vacuum vapor deposition method is preferably employed. The degree of vacuum at the time of this vapor deposition is usually 1.0 × 10 ⁻¹ Pa or less, preferably 1.0 × 10 ⁻³ Pa or less. Moreover, the characteristics of the organic semiconductor thin film change depending on the temperature of the deposit during vapor deposition. When an organic semiconductor thin film is used as a semiconductor layer of an organic semiconductor device (organic thin film transistor) to be described later, this changes the characteristics of the organic semiconductor device, so it is preferable to carefully select the temperature of the deposit during vapor deposition. . The temperature of the adherend during vapor deposition is usually 0 to 200 ° C, preferably 5 to 180 ° C, more preferably 10 to 150 ° C, still more preferably 15 to 120 ° C, and particularly preferably. 20 to 100 ° C. The deposition rate is usually 0.001 nm / second to 10 nm / second, preferably 0.01 nm / second to 1 nm / second. Moreover, the thickness of the organic-semiconductor thin film formed from the said organic-semiconductor material is 0.1 nm-10 micrometers normally, Preferably it is 0.5 nm-3 micrometers, More preferably, it is 1 nm-1 micrometer.

  The organic semiconductor thin film of the present invention can be used as an organic semiconductor thin film constituting a semiconductor layer in an organic semiconductor device, particularly an organic thin film transistor.

[Organic semiconductor device and manufacturing method thereof]
An organic semiconductor device can be produced using the condensed polycyclic aromatic compound represented by the general formula (1) as a material for electronics. The organic semiconductor device of the present invention includes the above-described organic semiconductor thin film of the present invention (that is, an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1)).

  The organic semiconductor device of this invention can be manufactured by the manufacturing method including the process of forming the organic-semiconductor thin film containing the condensed polycyclic aromatic compound represented by General formula (1). In the production of an organic semiconductor device, any of the methods for forming an organic semiconductor thin film of the present invention described above may be adopted as a method for forming an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1). A method for forming an organic semiconductor thin film by a solution process, specifically, the organic semiconductor material of the present invention described above is applied or printed on the surface on which the organic semiconductor thin film is to be formed, and the general formula (1) The method of forming the organic-semiconductor thin film containing the condensed polycyclic aromatic compound represented by these is more preferable.

  Examples of the organic semiconductor device include organic thin film transistors, photoelectric conversion devices, organic solar cell devices, organic EL devices, organic light emitting transistor devices, and organic semiconductor laser devices. These will be described in detail.

(Organic thin film transistor)
First, the organic thin film transistor will be described in detail.

  The organic thin film transistor includes at least one semiconductor layer made of an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1), and two electrodes disposed so as to be in contact with and separated from the semiconductor layer That is, another source called a gate electrode disposed so as to oppose a source electrode and a drain electrode and a region (channel region) between the surface in contact with the source electrode and the surface in contact with the drain electrode in the semiconductor layer. And a current flowing between the source electrode and the drain electrode is controlled by a voltage applied to the gate electrode.

  In general, an organic thin film transistor having a structure in which a gate electrode is insulated from a semiconductor layer by an insulator layer made of an insulating film (Metal-Insulator-Semiconductor) (MIS structure) is often used as the organic thin film transistor. A MIS structure using a metal oxide film as an insulating film is called a MOS (Metal-Oxide-Semiconductor) structure. As an organic thin film transistor having another structure, there is a structure in which a gate electrode is formed via a Schottky barrier with respect to a semiconductor layer (Metal-Semiconductor; MES structure), but in the case of an organic thin film transistor using an organic semiconductor, A MIS structure is often used.

  Hereinafter, although an organic thin-film transistor is demonstrated in detail using FIG. 1, this invention is not limited to these structures.

  In FIG. 1, the schematic sectional drawing of the some example of an organic thin-film transistor is shown. Organic thin-film transistors 10A to 10D and 10F of each embodiment shown in FIGS. 1 (a) to 1 (d) and (f) include a source electrode 1 and a condensed polycyclic aromatic compound represented by the general formula (1). At least one semiconductor layer 2 having an organic semiconductor thin film, a drain electrode 3, an insulator layer 4, a gate electrode 5, and a substrate 6 are provided. An organic thin film transistor 10E shown in FIG. 1E includes a source electrode 1, at least one semiconductor layer 2 having an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1), a drain electrode 3, and a gate electrode. 5 is provided. In addition, arrangement | positioning of each layer 2, 4 and the electrodes 1, 3, 5 can be suitably selected according to the use of an organic thin-film transistor.

  The organic thin film transistors 10A to 10D and 10F are called horizontal transistors because a current flows in a direction parallel to the substrate 6, the source electrode 1, and the drain electrode 3. The organic thin film transistor 10A and the organic thin film transistor 10F have a structure in which the source electrode 1 and the drain electrode 3 are disposed on the lower surface of the semiconductor layer 2 (the surface close to the substrate 6), and this structure is called a bottom contact structure. . The organic thin film transistor 10B and the organic thin film transistor 10C have a structure in which the source electrode 1 and the drain electrode 3 are disposed on the upper surface of the semiconductor layer 2 (the surface far from the substrate 6), and this structure is called a top contact structure. . The organic thin film transistor 10D has a structure in which one of the source electrode 1 and the drain electrode 3 is disposed on the upper surface of the semiconductor layer 2, and the other is disposed on the lower surface of the semiconductor layer 2. It is called a contact structure.

  The organic thin film transistor 10A, the organic thin film transistor 10B, and the organic thin film transistor 10D have a structure in which the gate electrode 5 is disposed below the semiconductor layer 2 (side closer to the substrate 6), and this structure is called a bottom gate structure. In the bottom gate structure, a single conductive substrate (for example, a silicon wafer) may serve as the gate electrode 5 and the substrate 6. The organic thin film transistor 10C and the organic thin film transistor 10F have a structure in which the gate electrode 5 is disposed on the upper side (the side far from the substrate 6) of the semiconductor layer 2, and this structure is called a top gate structure.

  Each component in each embodiment will be described.

  The substrate 6 needs to be able to hold each component formed thereon without peeling off. Examples of the substrate 6 include an insulating substrate such as a resin plate, a resin film, paper, a glass plate, a quartz plate, and a ceramic plate; a substrate in which an insulating layer is formed by coating or the like on a conductive substrate made of metal or an alloy; A substrate composed of various combinations such as a combination of a resin and an inorganic material; a conductive substrate such as a semiconductor substrate (for example, a silicon wafer) can be used. Examples of the resin constituting the resin plate and the resin film include, for example, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyamide, polyimide, polycarbonate, cellulose triacetate, and polyetherimide. When a resin film or paper is used as the substrate 6, the organic thin film transistors 10 </ b> A to 10 </ b> D and 10 </ b> F can be made flexible, so that the substrate 6 is flexible and lightweight, and the practicality of the organic thin film transistor is improved. The thickness of the substrate is usually 1 μm to 10 mm, preferably 5 μm to 5 mm.

For the source electrode 1, the drain electrode 3, and the gate electrode 5, a conductive material is used. Examples of the conductive material include platinum, gold, silver, aluminum, chromium, tungsten, tantalum, nickel, cobalt, copper, iron, lead, tin, titanium, indium, palladium, molybdenum, magnesium, calcium, and barium. Metals such as lithium, potassium, sodium and alloys containing them; conductive oxides such as InO ₂ , ZnO ₂ , SnO ₂ , ITO (indium tin oxide); polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene vinylene, Conductive polymer compounds such as polydiacetylene; semiconductors such as silicon, germanium, and gallium arsenide; carbon materials such as carbon black, fullerene, carbon nanotubes, graphite, and graphene can be used. Further, the conductive polymer compound or the semiconductor may be doped. Examples of dopants used for the doping include inorganic acids such as hydrochloric acid and sulfuric acid; organic acids having acidic functional groups such as sulfonic acid; Lewis acids such as PF ₅ , AsF ₅ and FeCl ₃ ; halogen atoms such as iodine; lithium , Metal atoms such as sodium and potassium. Boron, phosphorus, arsenic and the like are also frequently used as dopants for inorganic semiconductors such as silicon. In addition, a conductive composite material in which particles such as carbon black and metal particles are dispersed in the above dopant can also be used.

  Note that the source electrode 1 and the drain electrode 3 in contact with the semiconductor layer 2 can be subjected to selection of an appropriate work function for reducing contact resistance, surface treatment, and the like.

  Further, the distance (channel length) between the source electrode 1 and the drain electrode 3 is an important factor that determines the characteristics of the organic semiconductor device. The channel length is usually 0.01 to 300 μm, preferably 0.1 to 100 μm. If the channel length is short, the amount of current that can be extracted increases, but conversely, short channel effects such as the influence of contact resistance occur and control becomes difficult, so an appropriate channel length is required. The length (channel width) of the source electrode 1 and the drain electrode 3 is usually 10 to 10000 μm, preferably 100 to 5000 μm. In addition, this channel width can be made longer by making the electrode structure a comb-shaped structure, etc., and the channel width is made appropriate depending on the required current amount, device structure, etc. be able to.

  The structures (shapes) of the source electrode 1 and the drain electrode 3 will be described. The structures of the source electrode 1 and the drain electrode 3 may be the same or different.

  In the case of the bottom contact structure, the source electrode 1 and the drain electrode 3 are generally produced using a lithography method. Moreover, it is preferable to form these electrodes in a rectangular parallelepiped. Recently, the printing accuracy by various printing methods has been improved, and it has become possible to produce the source electrode 1 and the drain electrode 3 with high accuracy using techniques such as ink jet printing, gravure printing, or screen printing. In the case of a top contact structure in which the source electrode 1 and the drain electrode 3 are provided on the semiconductor layer 2, the source electrode 1 and the drain electrode 3 can be produced by vapor-depositing the conductive material using a shadow mask or the like. It has also become possible to directly print and form the electrode patterns of the source electrode 1 and the drain electrode 3 using a technique such as inkjet printing. The lengths of the source electrode 1 and the drain electrode 3 are the same as the channel width. The widths of the source electrode 1 and the drain electrode 3 are not particularly limited, but are preferably shorter in order to reduce the area of the device within a range where the electrical characteristics can be stabilized. The width of the source electrode 1 and the drain electrode 3 is usually 0.1 to 1000 μm, preferably 0.5 to 100 μm. The thicknesses of the source electrode 1 and the drain electrode 3 are usually 0.1 to 1000 nm, preferably 1 to 500 nm, and more preferably 5 to 200 nm. Although wiring is connected to the source electrode 1 and the drain electrode 3, the wiring is also made of the same material as the source electrode 1 and the drain electrode 3.

As the insulator layer 4, an insulating material is used. Examples of the insulating material include polyparaxylylene, polyacrylate, polymethyl methacrylate, polystyrene, polyvinylphenol, polyamide, polyimide, polycarbonate, polyester, polyvinyl alcohol, polyvinyl acetate, polyurethane, polysulfone, fluororesin, Polymers such as epoxy resins and phenol resins, and copolymers in which two or more structural units of these polymers are combined; oxides (not ferroelectric) such as silicon dioxide, aluminum oxide, titanium oxide, tantalum oxide; SrTiO ₃ , Ferroelectric oxides such as BaTiO ₃ ; nitrides such as silicon nitride and aluminum nitride; dielectrics such as sulfide and fluoride can be used. In addition, as the material having the insulating property, a material in which particles of the dielectric (however, a material different from the polymer) are dispersed in a polymer can be used. As the material having the insulating property, a material having high electrical insulation characteristics is preferable in order to reduce the leakage current. Thereby, the thickness of the insulator layer 4 can be reduced, the insulation capacity can be increased, and the current that can be taken out. Can be more. In order to improve the mobility of the semiconductor, it is preferable that the insulator layer 4 is a smooth film that can reduce the surface energy of the surface of the insulator layer 4 and has no unevenness. For this purpose, a self-assembled monolayer insulating layer 4 or a two-layered insulating layer 4 may be formed. The thickness of the insulator layer 4 varies depending on the material, but is usually 0.1 nm to 100 μm, preferably 0.5 nm to 50 μm, more preferably 5 nm to 10 μm.

  The semiconductor layer 2 has an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1). Even if the structure of the semiconductor layer 2 is a single layer structure having only the layer made of the organic semiconductor thin film of the present invention described above, a multilayer structure having a plurality of layers including the layer made of the organic semiconductor thin film of the present invention described above However, the single layer structure is preferable.

  The thickness of the semiconductor layer 2 is preferably as thin as possible without losing necessary functions. In a horizontal organic thin film transistor such as the organic semiconductors 10A to 10D and 10F, the characteristics of the organic semiconductor device do not depend on the thickness as long as the semiconductor layer 2 has a predetermined thickness or more. When the thickness becomes too thick, the leakage current often increases. For this reason, it is preferable that the thickness of the semiconductor layer 2 be in an appropriate range. The thickness of the semiconductor layer 2 is usually 0.1 nm to 10 μm, preferably 0.5 nm to 3 μm, more preferably 1 nm to 1 μm.

  In the organic thin film transistors 10 </ b> A to 10 </ b> F, other layers may be provided as necessary between the above-described components or on the exposed surfaces of the above-described components. For example, a protective layer may be formed directly or via another layer on the semiconductor layer 2 in the organic thin film transistors 10A to 10F. Thereby, the influence of outside air such as humidity on the electrical characteristics of the organic thin film transistor can be reduced, and the electrical characteristics of the organic thin film transistor can be stabilized. In addition, electrical characteristics such as the on / off ratio of the organic thin film transistor can be improved.

  Although it does not specifically limit as a material which comprises the said protective layer, For example, various resins, such as acrylic resins, such as an epoxy resin and polymethylmethacrylate, a polyurethane, a polyimide, polyvinyl alcohol, a fluororesin, polyolefin; silicon oxide, aluminum oxide, Inorganic oxides such as silicon nitride; and dielectrics such as nitrides are preferred, and resins (polymers) having low oxygen permeability, moisture permeability, and water absorption are more preferred. As a material constituting the protective layer, a gas barrier protective material developed for an organic EL display can also be used. Although the thickness of a protective layer can employ | adopt arbitrary thickness according to the objective, it is 100 nm-1 mm normally.

  Further, the surface of the semiconductor layer 2 (the surface of the substrate 6, the surface of the insulator layer 4, etc.) is subjected to surface modification or surface treatment in advance before the formation of the semiconductor layer 2, so that the organic thin film transistors 10A to 10F are obtained. It is possible to improve the characteristics. For example, by adjusting the degree of hydrophilicity / hydrophobicity of the surface on which the semiconductor layer 2 is formed, the quality of the semiconductor layer 2 formed on the surface (for example, the film quality of the organic semiconductor thin film constituting the semiconductor layer 2 or (Filmability) can be improved. In particular, the characteristics of the semiconductor layer 2 made of an organic semiconductor material may vary greatly depending on the state of the layer, such as molecular orientation. Therefore, the surface treatment on the surface on which the semiconductor layer 2 is formed controls the molecular orientation at the interface portion between the surface on which the semiconductor layer 2 is formed and the semiconductor layer 2 formed on the surface, and the semiconductor layer It is considered that the trap site in the base material (substrate 6, insulator layer 4, etc.) on which 2 is formed is reduced, thereby improving characteristics such as carrier mobility of the organic thin film transistor. The trap site means a functional group such as a hydroxyl group present in an untreated substrate. When such a functional group is present in the base material on which the semiconductor layer 2 is formed, electrons are attracted to the functional group, and as a result, the carrier mobility of the organic thin film transistor is lowered. Therefore, reducing trap sites in the substrate on which the semiconductor layer 2 is formed is often effective for improving characteristics such as carrier mobility of the organic thin film transistor.

  Examples of the surface treatment of the substrate on which the semiconductor layer 2 is formed include, for example, self-assembled monolayer treatment with hexamethyldisilazane, octyltrichlorosilane, octadecyltrichlorosilane, etc .; surface treatment with polymers, etc .; hydrochloric acid, sulfuric acid Acid treatment with acid such as acetic acid; alkali treatment with alkali such as sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia; ozone treatment; fluorination treatment; plasma treatment with plasma such as oxygen plasma or argon plasma; Langmuir Blow-jet film formation treatment; other insulator or semiconductor organic semiconductor thin film formation treatment; mechanical treatment; electrical treatment such as corona discharge; rubbing treatment using fibers, etc., and combinations of these treatments Can be mentioned.

  In the above-described organic thin film transistors 10A to 10F, a method of providing various layers on the substrate (a method of providing the insulator layer 4 on the substrate 6, a method of providing the insulator layer 2 on the substrate 6, a semiconductor on the insulator layer 4) As a method for providing the layer 2, etc., the above-described vacuum process and solution process can be appropriately employed.

(Method for producing organic thin film transistor)
Next, a method for manufacturing an organic thin film transistor according to the present invention will be described below with reference to FIG. 2 by taking the top contact-bottom gate type organic thin film transistor 10B of the embodiment shown in FIG. This manufacturing method can be similarly applied to the organic thin film transistor of another embodiment shown in FIG.

(1) Preparation of substrate 6 and surface treatment of substrate 6 In the method of manufacturing organic thin film transistor 10B, first, substrate 6 is prepared (see FIG. 2A), and various layers and electrodes necessary for substrate 6 are provided. Thus, the organic thin film transistor 10B is manufactured. As the substrate 6, those described above can be used. It is also possible to perform the above-described surface treatment on the substrate 6. The thickness of the substrate 6 is preferably thin as long as necessary functions are not hindered. If necessary, the substrate 6 may have an electrode function.

(2) Formation of Gate Electrode 5 Next, the gate electrode 5 is formed on the substrate 6 (see FIG. 2B). The material described above is used as the material constituting the gate electrode. As a method for forming the gate electrode 5, various methods can be used. For example, a vacuum deposition method, a sputtering method, a coating method, a thermal transfer method, a printing method, a sol-gel method, or the like can be employed. When forming a layer of a material (electrode material) constituting the gate electrode 5, or after forming the layer, it is preferable to pattern the layer so as to have a desired shape as necessary. Various methods can be used as the layer patterning method, and examples thereof include a photolithography method in which patterning and etching of a photoresist are combined. Also, evaporation method using shadow mask: sputtering method; printing method such as ink jet printing, screen printing, offset printing, letterpress printing, etc .; soft lithography method such as micro contact printing method; or a combination of these methods Thus, the layer can be patterned. The thickness of the gate electrode 5 varies depending on the material constituting the gate electrode 5, but is usually 0.1 nm to 10 μm, preferably 0.5 nm to 5 μm, and more preferably 1 nm to 3 μm. When a single conductive substrate serves as both the gate electrode 5 and the substrate 6, the thickness of the single conductive substrate may be larger than the above-described thickness range of the gate electrode 5.

(3) Formation of insulator layer 4 Next, the insulator layer 4 is formed on the gate electrode 5 (see FIG. 2C). As the material constituting the insulator layer 4, the materials described above are used. Various methods can be used to form the insulator layer 4. Examples of methods that can be used for forming the insulator layer 4 include spin coating, spray coating, dip coating, casting, bar coating, blade coating, and other coating methods; screen printing, offset printing, inkjet printing, and the like; Various methods such as a vacuum deposition method, a molecular beam epitaxial growth method, an ion cluster beam method, an ion plating method, a sputtering method, an atmospheric pressure plasma method, and a dry process method such as a CVD method can be used. In addition to the sol-gel method; a method of forming alumite on aluminum, or a method of forming silicon oxide on silicon, the surface layer of metal or metalloid is oxidized by a thermal oxidation method, etc. A method of forming an oxide film can also be employed.

  Note that, in a portion where the insulator layer 4 and the semiconductor layer 2 are in contact with each other, a molecule constituting the semiconductor layer 2 at the interface between the insulator layer 4 and the semiconductor layer 2, for example, a condensed polymolecule represented by the general formula (1) In order to satisfactorily orient the molecules of the ring aromatic compound, the insulator layer 4 can be subjected to a predetermined surface treatment. As a surface treatment method for the insulator layer 4, the same surface treatment as that for the substrate 6 can be used. The thickness of the insulator layer 4 is preferably as thin as possible because the amount of electricity taken out can be increased by increasing the electric capacity of the insulator layer 4. However, since the leakage current increases as the insulator layer 4 is thinner, the insulator layer 4 is preferably thinner as long as the function is not impaired. The thickness of the insulator layer 4 is as described above.

(4) Formation of Semiconductor Layer 2 Next, an organic semiconductor thin film is formed on the insulator layer 4 using an organic semiconductor material to obtain the semiconductor layer 2 (see FIG. 2D). In forming the semiconductor layer 2, the organic semiconductor thin film forming method of the present invention described above can be used. In this step, the object (attachment) on which the organic semiconductor thin film (semiconductor layer) is formed is the insulator layer 4 shown in FIG. 2C, and the surface on which the organic semiconductor thin film (semiconductor layer) is formed (deposition) Surface) is the upper surface of the insulator layer 4.

(5) Post-processing of Semiconductor Layer 2 The characteristics of the semiconductor layer 2 (see FIG. 2D) formed in this way can be further improved by post-processing. For example, by performing heat treatment as a post-treatment of the semiconductor layer 2, the semiconductor characteristics of the semiconductor layer 2 can be improved and stabilized. This is because the strain in the film generated when the organic semiconductor thin film constituting the semiconductor layer 2 is formed is reduced, pinholes in the semiconductor layer 2 are reduced, and the arrangement and orientation in the semiconductor layer 2 are reduced. Is considered to be able to control. Therefore, when the organic thin film transistor of the present invention is manufactured, the above heat treatment is effective for improving the characteristics of the organic thin film transistor. The heat treatment is performed by heating the stacked body including the semiconductor layer 2 (here, the stacked body shown in FIG. 2D) after the semiconductor layer 2 is formed. The temperature of the heat treatment is not particularly limited, but is usually room temperature or higher and 150 ° C. or lower, preferably 40 to 120 ° C., more preferably 45 to 100 ° C. The time for the heat treatment is not particularly limited, but is usually 10 seconds or longer and 24 hours or shorter, preferably 30 seconds or longer and 3 hours or shorter. Regarding the atmosphere of the heat treatment, the heat treatment may be performed in the air, or may be performed in an inert atmosphere such as nitrogen or argon. In addition, the shape of the semiconductor layer 2 can be controlled by the organic solvent vapor.

  Further, as another post-treatment method for the semiconductor layer 2, the semiconductor layer 2 is treated with an oxidizing gas such as oxygen, a reducing gas such as hydrogen, an oxidizing liquid, or a reducing liquid, thereby oxidizing the semiconductor layer 2. Or the characteristic change of the semiconductor layer 2 by reduction | restoration can also be induced. This can be used for the purpose of increasing or decreasing the carrier density in the semiconductor layer 2, for example.

In addition, the characteristics of the semiconductor layer 2 can be changed by adding a small amount of dopant (element, atomic group, molecule, or polymer) to the semiconductor layer 2 in a technique called doping. For example, oxidizing gases such as oxygen; reducing gases such as hydrogen; acids such as hydrochloric acid, sulfuric acid and sulfonic acid; Lewis acids such as PF ₅ , AsF ₅ and FeCl ₃ ; halogen atoms such as iodine; sodium and potassium The semiconductor layer 2 can be doped with a dopant such as a metal atom; a donor compound such as tetrathiafulvalene (TTF) or phthalocyanine. This is because a semiconductor layer 2 is brought into contact with a dopant in a gas state (when the dopant is a gas); a method in which the semiconductor layer 2 is immersed in a dopant in a solution state (when the dopant is in a solution state); This can be achieved by a method of processing. These dopants do not necessarily have to be added after the formation of the semiconductor layer 2, and are added when the material of the semiconductor layer 2 (organic semiconductor material) is synthesized or when the semiconductor layer 2 is formed using an organic semiconductor material. May be added to the organic semiconductor material or may be added in the process step of forming the semiconductor layer 2. In addition, a dopant is added to the material forming the semiconductor layer 2 (organic semiconductor material) and co-evaporated; the dopant is mixed in an ambient atmosphere when the semiconductor layer 2 is formed (in an environment in which the dopant exists) In addition, it is possible to perform doping by accelerating dopant ions in vacuum and colliding with the semiconductor layer 2 in a vacuum.

  These doping effects include changes in electrical conductivity due to increase or decrease in carrier density, changes in carrier polarity (p-type and n-type), changes in Fermi level, and the like.

(6) Formation of Source Electrode 1 and Drain Electrode 3 Next, the source electrode 1 and the drain electrode 3 are formed on the semiconductor layer 2 (see FIG. 2E). The method for forming the source electrode 1 and the drain electrode 3 can be based on the method for forming the gate electrode 5. In forming the source electrode 1 and the drain electrode 3, various additives or the like can be used to reduce the contact resistance with the semiconductor layer 2.

(7) Formation of the protective layer 7 In the step of forming the source electrode and the drain electrode 3 described above, the organic thin film transistor 10B (see FIG. 1B and FIG. 2E) is completed. After the formation of the source electrode 1 and the drain electrode 3, a protective layer 7 may be formed on the exposed portion of the upper surface of the semiconductor layer 2, the upper surface of the source electrode 1, and the upper surface of the drain electrode 3 (FIG. 2). (Refer to (f)). When the protective layer 7 is formed on the exposed portion of the upper surface of the semiconductor layer 2, the upper surface of the source electrode 1, and the upper surface of the drain electrode 3, the influence of outside air can be minimized. There is an advantage that the mechanical characteristics can be stabilized.

  As the material for the protective layer 7, the above-mentioned materials are used. Moreover, the thickness of the protective layer 7 can employ | adopt arbitrary thickness according to the objective, Usually, it is 100 nm-1 mm.

  As a method of forming the protective layer 7, various methods can be adopted. When the protective layer 7 is made of a resin, for example, a method of applying a solution containing a resin and drying it to obtain a resin layer; Examples thereof include a method of polymerizing after applying or vapor-depositing a resin monomer. You may perform a crosslinking process after formation of a resin layer. When the protective layer 7 is made of an inorganic material, as a method for forming the protective layer 7, for example, a forming method by a vacuum process such as a sputtering method or a vapor deposition method; a forming method by a solution process such as a sol-gel method can be used. .

  In the organic thin film transistor, a protective layer can be provided as necessary between the constituent elements in addition to the semiconductor layer. Such a protective layer may help to stabilize the electrical characteristics of the organic thin film transistor.

  Since the organic thin film transistor of the present invention uses an organic semiconductor material containing the condensed polycyclic aromatic compound represented by the general formula (1) as a material constituting the semiconductor layer, it can be manufactured in a relatively low temperature process. It is. Therefore, in the organic thin film transistor of the present invention, a flexible material such as a plastic plate or a plastic film that could not be used under conditions exposed to a high temperature can be used as the substrate. As a result, in the organic thin film transistor of the present invention, by using a flexible material as a substrate, an organic semiconductor device that is light and flexible and is not easily broken can be realized, and is suitably used as a switching device for an active matrix display. be able to.

  The organic thin film transistor of the present invention can also be used as a digital device or an analog device such as a memory circuit device, a signal driver circuit device, and a signal processing circuit device. Further, by combining these, a display, an IC (integrated circuit) card, an IC tag, or the like can be manufactured. Furthermore, since the organic thin film transistor of the present invention can change its characteristics by an external stimulus such as a chemical substance, it can be used as a sensor.

(Organic EL device)
The organic semiconductor device of the present invention can be used as an organic EL device.

  Organic EL devices have attracted attention because they can be used in applications such as solid, self-luminous large-area color display and illumination, and many developments have been made. The organic EL device has a structure in which two layers of a light emitting layer and a charge transport layer are provided between a counter electrode composed of a cathode and an anode; an electron transport layer, a light emitting layer and a positive electrode laminated between the counter electrodes. Known are those having a structure having three layers of hole transport layers; and those having a structure having three or more layers, and those having a single light emitting layer.

  When the organic semiconductor device of the present invention is used as an organic EL device, the organic semiconductor thin film containing the condensed polycyclic aromatic compound represented by the general formula (1) functions as the charge transport layer or the electron transport layer. Can do.

(Photoelectric conversion device)
The organic semiconductor device of the present invention can be used as a photoelectric conversion device by utilizing the semiconductor characteristics of the condensed polycyclic aromatic compound represented by the general formula (1).

  Examples of the photoelectric conversion device include a charge coupled device (CCD) having a function of converting a video signal such as a moving image or a still image into a digital signal as an image sensor that is a solid-state imaging device. The organic semiconductor material containing the condensed polycyclic aromatic compound represented by the general formula (1) is inexpensive and can be used as a material for a photoelectric conversion device by taking advantage of large area processability, flexible functionality unique to organic matter, and the like. Expected to be used.

(Organic solar cell device)
A flexible and low-cost organic solar cell device can be easily produced using the condensed polycyclic aromatic compound represented by the general formula (1). Since the organic solar cell device is a solid-state device, it is advantageous in terms of flexibility and improved life. Conventionally, development of solar cells using organic thin film semiconductors combined with conductive polymers, fullerenes, and the like has been the mainstream, but power generation conversion efficiency is a problem.

  In general, the structure of an organic solar cell device is similar to that of a silicon-based solar cell, in which a layer for generating power (a power generation layer) is sandwiched between an anode and a cathode, and holes and electrons generated by absorbing light are absorbed by each electrode. By receiving it functions as a solar cell. The power generation layer is composed of a p-type donor material, an n-type acceptor material, and other materials such as a buffer layer, and an organic solar cell is used for the material.

  Structures include Schottky junctions, heterojunctions, bulk heterojunctions, nanostructure junctions, hybrids, etc. Each material efficiently absorbs incident light and generates charges, and the generated charges (holes and electrons) It functions as a solar cell by separating, transporting and collecting.

  In FIG. 3, the schematic sectional drawing of the example (organic solar cell device 20) of a heterojunction type organic solar cell device is shown.

  The organic solar cell device 20 includes a substrate 21, an anode 22 formed on the upper surface of the substrate 21, a power generation layer 23 formed on the upper surface of the anode 22, and a cathode 24 formed on the upper surface of the power generation layer 23. And the power generation layer 23 is formed on the upper surface of the anode 22, the n-type layer 232 formed on the upper surface of the p-type layer 231, and the upper surface of the n-type layer 232. And the buffer layer 233.

  Next, each component in the organic solar cell device will be described by taking the organic solar cell device 20 shown in FIG. 3 as an example.

  As the material of the substrate 21, the same material as the substrate 6 of the organic thin film transistors 10A to 10F described above can be used.

  As a material constituting the anode 22 and the cathode 24 in the organic solar cell device 20, the same materials as those constituting the source electrode 1, the drain electrode 3, and the gate electrode 5 of the organic thin film transistors 10A to 10F described above are used. it can. Since the anode 22 and the cathode 24 need to capture light efficiently, it is desirable that the anode 22 and the cathode 24 have transparency in the absorption wavelength region of the power generation layer 23. In order for the organic solar cell device 20 to have good solar cell characteristics, the anode 22 and the cathode 24 have a sheet resistance of 20Ω / □ or less and a light transmittance of 85% or more. preferable.

  The power generation layer 23 is represented by the general formula (1) even if the power generation layer 23 has a single-layer structure including only a layer made of an organic semiconductor thin film containing the condensed polycyclic aromatic compound represented by the general formula (1). Although it may be a multilayer structure composed of a plurality of layers including a layer made of an organic semiconductor thin film containing a condensed polycyclic aromatic compound, generally, the power generation layer 23 is a p-type made of a p-type donor material. A layer 231, an n-type layer 232 made of an n-type acceptor material, and a buffer layer 233 are included.

  As a p-type donor material constituting the p-type layer 231, a compound capable of transporting holes can be basically used. Specifically, a polyparaphenylene vinylene derivative, a polythiophene derivative, a polyfluorene derivative, a polyaniline derivative, etc. π-conjugated polymers; carbazole and other polymers having heterocyclic side chains. Examples of the p-type donor material include low molecular compounds such as pentacene derivatives, rubrene derivatives, porphyrin derivatives, phthalocyanine derivatives, indigo derivatives, quinacridone derivatives, merocyanine derivatives, cyanine derivatives, squalium derivatives, and benzoquinone derivatives.

  As the n-type acceptor material constituting the n-type layer 232, an n-type acceptor material containing a condensed polycyclic aromatic compound represented by the general formula (1) can be used. That is, the n-type layer 232 is composed of an organic semiconductor thin film containing a condensed polycyclic aromatic compound represented by the general formula (1). As the n-type acceptor material constituting the n-type layer 232, the condensed polycyclic aromatic compound represented by the general formula (1) may be used alone, or the condensation represented by the general formula (1). You may mix and use a polycyclic aromatic compound and another acceptor material. Other acceptor materials to be mixed are basically compounds capable of transporting electrons, oligomers and polymers having pyridine or a derivative thereof as a skeleton, oligomers or polymers having a quinoline or a derivative thereof as a skeleton, benzophenanthrolines or Polymer materials having such derivatives, polymer materials such as cyanopolyphenylene vinylene derivatives (CN-PPV, etc.); low molecular materials such as fluorinated phthalocyanine derivatives, perylene derivatives, naphthalene derivatives, bathocuproine derivatives, fullerene derivatives such as C60, C70, PCBM Etc.

  As the p-type donor material and the n-type donor material, those capable of efficiently absorbing light and generating electric charges are preferable, and those having a high extinction coefficient are preferable.

  Examples of the material of the buffer layer 233 include copper phthalocyanine, molybdenum trioxide, calcium, nickel oxide, lithium fluoride, and polyethylenedioxythiophene doped with polystyrene sulfonic acid (PEDOT: PSS).

  As a method for forming the organic semiconductor thin film for the power generation layer 23 in the organic solar cell device 20, a method similar to the method for forming the semiconductor layer in the organic thin film transistor described above can be employed. The thickness of the power generation layer 23 varies depending on the configuration of the organic solar cell device. However, the thicker the layer, the thicker the light can be absorbed and the short circuit can be prevented. Can do. For this reason, the thickness of the power generation layer 23 is preferably about 10 to 500 nm.

(About organic semiconductor laser devices)
Since the condensed polycyclic aromatic compound represented by the general formula (1) is a compound having semiconductor characteristics, it is expected to be used as an organic semiconductor laser device.

  That is, if a resonator structure is incorporated in the organic semiconductor device of the present invention and carriers are efficiently injected to sufficiently increase the density of the excited state, it is expected that light is amplified and laser oscillation occurs. Conventionally, only laser oscillation by optical excitation has been observed, and it is extremely difficult to inject high-density carriers required for laser oscillation by electrical excitation into an organic semiconductor device to generate a high-density excitation state. Has been advocated. However, the use of an organic semiconductor device including an organic semiconductor thin film containing the compound represented by the general formula (1) is expected to cause highly efficient light emission (electroluminescence).

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to this.

[Outline of Synthesis Method of Target Compound in Examples and Comparative Examples]
In the following examples and comparative examples, the compound 100 (7-phenylBTBT) having a phenyl group, a phenyl group and a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 4 carbon atoms, as shown in the following formulas and tables. 1 to 4, 6 and 101 to 106 (2-alkyl-7-phenyl BTBT) having the above and compounds 18, 26 and 32 having a naphthyl group or tolyl group and a linear alkyl group having 4 carbon atoms. did.

  The target compounds 1 to 4, 6 and 101 to 106 are intermediate compounds 121 to 131 shown in the following formulas and tables using compounds 110 to 120 (monoalkyl BTBT; 2-alkyl BTBT) shown in the following formulas and tables as raw materials. Was synthesized from intermediate compounds 121-131.

  That is, as shown in the following scheme 4, bromination is performed using compounds 110 to 120 as raw materials to obtain intermediate compounds 121 to 131, and then the target compounds 1 to 4 are coupled by an arylboronic acid coupling reaction. 6 and 101-106 were synthesized.

For the target compound 100 (R ¹² = H), as shown in the following scheme 5, bromination is performed using BTBT as a raw material to obtain an intermediate compound 132 which is a bromine monosubstituted BTBT (2-bromoBTBT). After obtaining, it was synthesized by the same coupling reaction with phenylboronic acid as in Scheme 3.

  Compounds 111 to 120 were synthesized from intermediate compounds 140 to 149 after synthesizing intermediate compounds 140 to 149 shown in the following formulas and tables using BTBT as a starting material.

  That is, as shown in Scheme 6 below, after performing Friedel-Crafts reaction using BTBT as a starting material to obtain intermediate compounds 140 to 149, intermediate compounds 140 to 149 are reduced to reduce compounds 111 to 120 was synthesized.

  Since compound 110 (2-methyl BTBT) cannot be obtained by the method of Scheme 6, as shown in Scheme 7 below, intermediate compound 132 which is a bromine monosubstituted BTBT by performing bromination using BTBT as a starting material Then, the intermediate compound 132 was subjected to a coupling reaction with methylboronic acid to obtain a compound 110.

[Example 1] (Synthesis of target compound 4 (2-butyl-7-phenylBTBT))
(Synthesis of Intermediate Compound 143)
First, an intermediate compound 143, which is an intermediate for the synthesis of the compound 113 which is a mono C4 alkyl BTBT, was synthesized. That is, 3.0 g (12.5 mmol) of BTBT was dissolved in dichloromethane, and 4.0 g (37.4 mmol, 3.0 equivalents) of butyryl chloride and 5.0 g (37.4 mmol) of aluminum chloride were added to the obtained solution. , 3.0 equivalents) were added in order, and the mixture was stirred at room temperature for 1 hour. After completion of the stirring, the reaction solution was poured into a 2N aqueous hydrochloric acid solution, stirred for a while, and then extracted by adding chloroform. The organic layer was dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain a yellow solid. The obtained solid was recrystallized from chloroform to obtain pale yellow crystals of intermediate compound 143 (yield 2.9 g, yield 74%). ¹ H-NMR spectrum of the obtained intermediate compound 143 and measurement results of gas chromatograph mass spectrometry (hereinafter abbreviated as “GC / MS” where appropriate) by electron ionization (hereinafter abbreviated as “EI” where appropriate) Is shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.55 (d, J = 1.5 Hz, 1H, ArH), 8.06 (dd, J = 1.5 Hz, 1H, ArH), 7.95-7.92 (m, 3H, ArH) , 7.50-7.44 (m, 2H, ArH), 3.06 (t, J = 7.4Hz, 2H, COCH 2), 1. 84 (tq, J = 7.4, 7.4 Hz, 2H, CH ₂ ), 1.05 (t, J = 7.4 Hz, 3H, CH ₃ )
GC / MS (EI): m / z = 310.1

(Synthesis of Compound 113 (2-butyl BTBT))
Next, the compound 113 which is mono C4 alkyl BTBT was synthesized using the intermediate compound 143 obtained in the previous step as a raw material.

2.8 g (9.0 mmol) of intermediate compound 143, 2.5 g (45.0 mmol, 5.0 equivalents) of KOH, and 2.3 g (45.0 mmol, 5.0 equivalents) of hydrazine monohydrate were mixed with diethylene glycol. The mixture was mixed and stirred at 120 ° C. for 1 hour and at 180 ° C. for 3 hours. After allowing to cool, the reaction solution was poured into a 2N aqueous hydrochloric acid solution, stirred for a while, and then extracted with chloroform. The organic layer was dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain a yellow solid. The obtained solid was purified by column chromatography (filler: silica gel, developing solvent: hexane), and recrystallized with a chloroform / ethanol mixed solvent to obtain colorless flaky crystals of Compound 113 (yield 1.8 g). , Yield 68%). ^{1 H-NMR} spectrum of the resulting compound 113, and shows the measurement results of the gas chromatographic mass spectrometry by electron ionization below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 7.90 (d, J = 8.0 Hz, 1H, ArH), 7.86 (dd, J = 1.0, 7.8 Hz, 1H) , ArH), 7.78 (d, J = 8.0 Hz, 1H, ArH), 7.72 (s1H, ArH), 7.43 (ddd, J = 7.8, 7.8, 1.0 Hz, 1H, ArH), 7.38 (ddd, J = 7.8, 7.8, 1.3 Hz, 1H, ArH), 7.28 (dd, J = 7.8, 1.3 Hz, 1H, ArH) , 2.77 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 1.68 (tt, J = 7.7 Hz, 2H, CH ₂ ), 1.40 (tq, J = 7.7 Hz, CH ₂ ), 0.96 (q, J = 7.7 Hz, CH ₃ )
GC / MS (EI): m / z = 296.1

(Synthesis of Intermediate Compound 124)
The intermediate compound 124 was synthesized from 500 mg (1.7 mmol) of the compound 113 using the compound 113, which is a mono-C4 alkyl BTBT, as a raw material by the same synthesis method as the synthesis of the intermediate compound 132 in Example 4. That is, 500 mg (1.7 mmol) of Compound 113 was dissolved in dichloromethane, 300 mg (1.1 equivalents) of bromine in dichloromethane was added dropwise to the resulting solution, and the mixture was stirred at room temperature for 3 hours. After completion of the stirring, a 5% by weight aqueous sodium thiosulfate solution was added until the color of the solution became white to light yellow, followed by extraction with chloroform. The organic layer was dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain a yellow solid. The obtained solid was recrystallized from chloroform to obtain colorless plate crystals of intermediate compound 124 (yield 250 mg, yield 41%). ¹ H-NMR spectrum of the obtained intermediate compound 124 and measurement results of gas chromatograph mass spectrometry by electron ionization are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.02 (d, J = 1.7 Hz, 1H, ArH), 7.76 (d, J = 8.0 Hz, 1H, ArH), 7.70 (s, 1H, ArH), 7.69 (d, J = 8.5 Hz, 1H, ArH), 7.53 (dd, J = 1.7, 8.5 Hz, 1H, ArH), 7 .28 (d, J = 8.0 Hz, 1H, ArH), 2.76 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 1.68 (tt, J = 7.7 Hz, 2H, CH ₂₎ ), 1.40 (tq, J = 7.7 Hz, 2H, CH ₂ ), 0.95 (t, J = 7.7 Hz, 3H, CH ₃ )
GC / MS (EI): m / z = 376.0 (100%), 374.0 (90%)

(Synthesis of Target Compound 4)
Under an argon atmosphere, 376 mg (1.0 mmol) of intermediate compound 124, 58 mg (0.05 mmol, 5 mol%) of Pd (PPh ₃ ) _4, 415 mg (3 mmol, 3.0 equivalents) of K ₂ CO ₃ , and phenylboronic acid 183 mg (1.5 mmol, 1.5 equivalents) was stirred at 90 ° C. for 14 hours in a mixed solvent of toluene: water = 8: 1 (volume ratio). After allowing to cool, 2N aqueous hydrochloric acid solution was added, and the mixture was extracted with ethyl acetate. The organic layer was washed with a 2N hydrochloric acid aqueous solution and a saturated aqueous sodium bicarbonate solution in that order and then dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a pale yellow solid. The obtained solid was purified by column chromatography (silica gel, developing solvent: hexane / ethyl acetate = 50/1) and then recrystallized from a mixed solvent of chloroform / ethanol to obtain colorless flaky crystals of target compound 4. The ¹ H-NMR spectrum, ¹³ C-NMR spectrum, and melting point measurement of the obtained target compound 4 (measured using a melting point measuring apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.11 (d, J = 1.5 Hz, 1H, ArH), 7.91 (d, J = 8.1 Hz, 1H, ArH), 7.79 (d, J = 8.1 Hz, 1H, ArH), 7.73 (s, 1H, ArH), 7.73-7.68 (m, 3H, ArH), 7.48 (dd, J = 7.5, 7.5 Hz, 2H, ArH), 7.38 (ddd, J = 7.5, 7.5, 1, 4 Hz, 1H, ArH), 7.29 (dd, J = 8.1) , 1.5 Hz, 1H, ArH), 2.77 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 1.70 (tt, J = 7.7 Hz, 2H, CH ₂ ), 1.41 ( tq, J = 7.7 Hz, 2H, CH ₂ ), 0.96 (t, J = 7.7 Hz, 3H, CH ₃ )
¹³ C-NMR (125 MHz, CDCl ₃ ): δ (ppm) = 143.3, 143.1, 141.2, 140.8, 138.5, 134.1, 132.8, 131.5, 129. 3,127.8,127.7,126.4,124.9,123.8,122.7,122.0,121.7,36.2,34.2,22.8,14.4
Melting point: 244.5-246.0 ° C

[Example 2] (Synthesis of target compound 3 (2-propyl-7-phenylBTBT))
The target compound 3 was synthesized in the same manner as in Example 1 except that propionyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents). The ¹ H-NMR spectrum and measurement of the melting point of the obtained target compound 3 (measured using a melting point measurement apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.11 (d, J = 1.6 Hz, 1H, ArH), 7.91 (d, J = 8.3 Hz, 1H, ArH), 7.79 (d, J = 8.3 Hz, 1H, ArH), 7.73 (s, 1H, ArH), 7.71-7.68 (m, 3H, ArH), 7.49 (dd, J = 7.7, 7.7 Hz, 2H, ArH), 7.38 (dd, J = 7.7, 7.7 Hz, 1H, ArH), 7.29 (dd, J = 8.2, 1.6 Hz) , 1H, ArH), 2.76 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 1.74 (tq, J = 7.7 Hz, 2H, CH ₂ ), 1.00 (s, 3H, CH ₃₎
Melting point: 258.5-261.5 ° C

[Example 3] (Synthesis of target compound 2 (2-ethyl-7-phenylBTBT))
The target compound 2 was synthesized in the same manner as in Example 1 except that acetyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents). The ¹ H-NMR spectrum and measurement of the melting point of the obtained target compound 2 (measured using a melting point measurement apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.12 (d, J = 1.4 Hz, 1H, ArH), 7.91 (d, J = 8.1 Hz, 1H, ArH), 7.80 (d, J = 8.1 Hz, 1H, ArH), 7.75 (s, 1H, ArH), 7.73-7.68 (m, 3H, ArH), 7.48 (dd, J = 7.7, 7.7 Hz, 2H, ArH), 7.40 (ddd, J = 7.7, 7.7, 1, 4 Hz, 1H, ArH), 7.31 (dd, J = 8.1) , 1.4 Hz, 1H, ArH), 2.82 (q, J = 7.7 Hz, 2H, ArCH ₂ ), 1.34 (t, J = 7.7 Hz, 3H, CH ₃ )
Melting point: 264.0-266.0 ° C

[Example 4] (Synthesis of target compound 1 (2-methyl-7-phenylBTBT))
(Synthesis of Intermediate Compound 132)
First, BTBT was brominated to obtain an intermediate compound 132. That is, 3 g (12.5 mmol) of BTBT was dissolved in dichloromethane, and a dichloromethane solution of 2.2 g (1.1 equivalents) of bromine was added dropwise to the resulting solution, followed by stirring at room temperature for 3 hours. After completion of the stirring, a 5% by weight aqueous sodium thiosulfate solution was added until the color of the solution became white to light yellow, followed by extraction with chloroform. The organic layer was dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain a yellow solid. The obtained solid was recrystallized from chloroform to obtain colorless plate crystals of intermediate compound 132 (yield 1.6 g, yield 40%). Obtained are shown ^{1 H-NMR} spectrum of the intermediate compound 132, and the measurement results of the gas chromatographic mass spectrometry by electron ionization below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.06 (d, J = 8.0 Hz, 1H, ArH), 7.92 (d, J = 8.0 Hz, 1H, ArH), 7.88 (d, J = 8.0 Hz, 1H, ArH), 7.73 (d, J = 8.0 Hz, 1H, ArH), 7.57-7.55 (m, 1H, ArH), 7 .49-7.41 (m, 2H, ArH)
GC / MS (EI): m / z = 317.9 (100%), 319.9 (90%)

(Synthesis of Compound 110 (2-methyl BTBT))
Next, compound 110, which is monomethyl BTBT, was synthesized using intermediate compound 132 obtained in the previous step as a raw material. 2.5 g (7.8 mmol) of intermediate compound 120 mixed with DMF under argon atmosphere, 0.64 g (0.78 mmol, 10 mol%) of PdCl ₂ (dppf) · CH ₂ Cl ₂ , K ₃ PO ₄ 4. 96 g (23.4 mmol, 3.0 equivalents) and 1.40 g (23.4 mmol, 3.0 equivalents) of methyl boronic acid were stirred at 90 ° C. for 6 hours. After allowing to cool, 2N aqueous hydrochloric acid solution was added, and the mixture was extracted with chloroform. The organic layer was washed with a 2N aqueous hydrochloric acid solution, further washed with a saturated aqueous sodium bicarbonate solution, and then dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain a brown solid. The obtained solid was purified by column chromatography (filler: silica gel, developing solvent: hexane) and high performance liquid chromatography (eluent: chloroform), and then recrystallized with a chloroform / ethanol mixed solvent to obtain compound 110. Colorless flaky crystals were obtained (yield 1.4 g, yield 69%). ^{1 H-NMR} spectrum of the resulting compound 110, and shows the measurement results of the gas chromatographic mass spectrometry by electron ionization below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 7.91 (d, J = 8.0 Hz, 1H, ArH), 7.85 (d, J = 7.7 Hz, 1H, ArH), 7.76 (d, J = 8.0 Hz, 1H, ArH), 7.73 (s, 1H, ArH), 7.45 (ddd, J = 1.0, 7.7, 8.0 Hz, 1H, ArH), 7.38 (ddd, J = 1.0, 7.7, 8.0 Hz, 1H, ArH), 7.27 (d, J = 8.0 Hz, 1H, ArH), 2.52 (s , 3H, CH ₃ )
GC / MS (EI): m / z = 254.0

(Synthesis of Intermediate Compound 121)
Next, in the same manner as in the synthesis of the intermediate compound 124 and the synthesis of the target compound 4 in Example 1 except that the compound 110 obtained in the previous step is used as a raw material instead of the compound 113 (14 hours at 90 ° C.) The target compound 1 was synthesized. The ¹ H-NMR spectrum and melting point measurement of the obtained target compound 1 (measured using a melting point measurement apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.11 (s, 1H, ArH), 7.91 (d, J = 8.2 Hz, 1H, ArH), 7.79 (d, J = 8.2 Hz, 1H, ArH), 7.73 (s, 1H, ArH), 7.73-7.68 (m, 3H, ArH), 7.48 (dd, J = 7.7, 7 .7 Hz, 2H, ArH), 7.38 (dd, J = 7.7, 7.7 Hz, 1H, ArH), 7.29 (d, J = 8.2 Hz, 1H, ArH), 2.53 ( s, 3H, ArCH ₃ )
Melting point: 211.0-213.5 ° C

[Example 5] (Synthesis of target compound 6 (2-isobutyl-7-phenylBTBT))
The target compound 6 was synthesized in the same manner as in Example 1 except that isobutyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents). The ¹ H-NMR spectrum and measurement of the melting point of the obtained target compound 6 (measured using a melting point measurement apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.12 (d, J = 1.4 Hz, 1H, ArH), 7.91 (d, J = 8.1 Hz, 1H, ArH), 7.80 (d, J = 8.1 Hz, 1H, ArH), 7.75 (s, 1H, ArH), 7.73-7.68 (m, 3H, ArH), 7.48 (dd, J = 7.7, 7.7 Hz, 2H, ArH), 7.40 (ddd, J = 7.7, 7.7, 1, 4 Hz, 1H, ArH), 7.31 (dd, J = 8.1) , 1.4 Hz, 1 H, ArH), 2.63 (d, J = 7.5 Hz, 2 H, ArCH ₂ ), 1.96 (m, 1 H, CH), 0.94 (d, J = 7.5 Hz , 6H, CH ₃ )
Melting point: 234.0-236.0 ° C

[Example 6] (Synthesis of target compound 18 (2-butyl-7- (2-naphthyl) BTBT))
The target compound 18 was synthesized in the same manner as in Example 1 except that 2-naphthylboronic acid (1.5 equivalents) was used instead of phenylboronic acid (1.5 equivalents). The ¹ H-NMR spectrum and measurement of the melting point of the target compound 18 obtained (measured using a melting point measurement apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory Co., Ltd.) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.25 (s, 1H, ArH), 8.15 (s, 1H, ArH), 7.97-7.81 (m, 7H, ArH), 7.75 (s, 1H, ArH), 7.52 (m, 2H, ArH), 7.30 (d, J = 8.0 Hz, 1H, ArH), 2.78 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 1.70 (tt, J = 7.7 Hz, 2H, CH ₂ ), 1.40 (tq, J = 7.7 Hz, 2H, CH ₂ ), 0.96 ( t, J = 7.7 Hz, 3H, CH ₃ )
Melting point: 280.0-282.0 ° C

[Example 7] (Synthesis of target compound 26 (2-butyl-7- (p-tolyl) BTBT))
The target compound 26 was synthesized in the same manner as in Example 1 except that p-tolylboronic acid (1.5 equivalents) was used instead of phenylboronic acid (1.5 equivalents). The ¹ H-NMR spectrum and melting point measurement (measured using melting point measuring apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory Co., Ltd.) of the obtained target compound 26 are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.08 (d, 1H, J = 1.0 Hz, ArH), 7.89 (d, J = 8.1 Hz, 1H, ArH), 7.78 (d, J = 8.1 Hz, 1H, ArH), 7.72 (s, 1H, ArH), 7.65 (dd, J = 1.0, 8.1 Hz, 1H, ArH), 7 .58 (m, 2H, ArH), 7.29 (m, 3H, ArH), 2.77 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 2.42 (s, 3H, PhCH ₃ ) 1.70 (tt, J = 7.7 Hz, 2H, CH ₂ ), 1.40 (tq, J = 7.7 Hz, 2H, CH ₂ ), 0.96 (t, J = 7.7 Hz, 3H) , CH ₃ )
Melting point: 260.5-262.0 ° C

[Example 8] (Synthesis of target compound 32 (2-butyl-7- (m-tolyl) BTBT))
The target compound 32 was synthesized in the same manner as in Example 1 except that m-tolylboronic acid (1.5 equivalent) was used instead of phenylboronic acid (1.5 equivalent). The ¹ H-NMR spectrum and the measurement of the melting point of the obtained target compound 32 (measured using a melting point measurement apparatus MP-S3 manufactured by Yanaco Instrument Development Laboratory Co., Ltd.) are shown below.
¹ H-NMR (500 MHz, CDCl ₃ ): δ (ppm) = 8.11 (s, 1H, ArH), 7.90 (d, J = 8.0 Hz, 1H, ArH), 7.79 (d, J = 8.0 Hz, 1H, ArH), 7.73 (s, 1H, ArH), 7.68 (dd, J = 1.0, 8.0 Hz, 1H, ArH), 7.50 (m, 2H) , ArH), 7.37 (dd, J = 8.0, 8.0 Hz, 1H, ArH), 7.28 (d, J = 8.0 Hz, 1H, ArH), 7.20 (d, J = 8.0 Hz, 1H, ArH), 2.77 (t, J = 7.7 Hz, 2H, ArCH ₂ ), 2.46 (s, 3H, PhCH ₃ ), 1.70 (tt, J = 7.7 Hz) , 2H, CH ₂ ), 1.40 (tq, J = 7.7 Hz, 2H, CH ₂ ), 0.97 (t, J = 7.7 Hz, 3H, C H ₃₎
Melting point: 192.0-194.0 ° C

[Comparative Example 1] (Synthesis of target compound 106 (2-decyl-7-phenylBTBT))
The target compound 106 was synthesized in the same manner as in Example 1 except that decanoyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents).

[Comparative Example 2] (Synthesis of target compound 105 (2-nonyl-7-phenylBTBT))
The target compound 105 was synthesized in the same manner as in Example 1 except that nonanoyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents).

[Comparative Example 3] (Synthesis of target compound 104 (2-octyl-7-phenylBTBT))
The target compound 104 was synthesized in the same manner as in Example 1 except that octanoyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents).

[Comparative Example 4] (Synthesis of target compound 103 (2-heptyl-7-phenylBTBT))
The target compound 103 was synthesized in the same manner as in Example 1 except that heptanoyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents).

[Comparative Example 5] (Synthesis of target compound 102 (2-hexyl-7-phenylBTBT))
The target compound 102 was synthesized in the same manner as in Example 1 except that hexanoyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents).

[Comparative Example 6] (Synthesis of target compound 101 (2-pentyl-7-phenylBTBT))
The target compound 101 was synthesized in the same manner as in Example 1 except that pentanoyl chloride (3.0 equivalents) was used instead of butyryl chloride (3.0 equivalents).

[Comparative Example 7] (Synthesis of target compound 100 (2-phenylBTBT))
(Synthesis of Intermediate Compound 120)
First, an intermediate compound 120 was obtained in the same manner as the synthesis of the intermediate compound 120 of Example 4.

(Synthesis of target compound 100)
The target compound 100 was synthesized in the same manner as the synthesis of the target compound 4 in Example 1, except that the intermediate compound 120 obtained as described above was used as a raw material.

[Single crystal structure analysis]
For the compound of Example 1 (alkyl chain length 4, C4), a 4-axis single crystal X-ray diffractometer (model number “AFC-7R”) manufactured by Rigaku Corporation and a detector (trade name “MercuryCCD” manufactured by Rigaku Corporation) )), The single crystal structure analysis was performed under the conditions of X-ray source: Mo and measurement temperature: 20 ° C. Further, the compound of Comparative Example 1 (alkyl chain length 6, C6), the compound of Comparative Example 3 (alkyl chain length 8, C8), and the compound of Comparative Example 5 (alkyl chain length 10, C10) are manufactured by Rigaku Corporation. Photon factories BL-8A and BL-8B of the High Energy Accelerator Research Organization, which is a customized imaging plate type single crystal X-ray diffractometer, are used as an X-ray source: synchrotron radiation (wavelength λ = 1. 55)), measurement temperature: single crystal structure analysis was performed at 20 ° C. About the compound (C3) of Example 2 and the compound (C5) of Comparative Example 6, X was measured using a curved imaging plate single crystal automatic X-ray structure analyzer (trade name “R-AXIS RAPIDII”) manufactured by Rigaku Corporation. Single crystal structure analysis was performed under the conditions of radiation source: Cu, measurement temperature: 20 ° C.

  The crystal structures of the compounds of Example 1 and Comparative Examples 1, 3, and 5 are shown in FIG. 4, and the crystal structures of the compounds of Examples 1 and 2 and Comparative Examples 1, 3, 5, and 6 are shown in FIG. Show.

  It was found that the crystal structures of the compounds of Comparative Examples 1, 3, 5, and 6 exhibited a bilayer structure as shown in FIGS. On the other hand, the crystal structures of the compounds of Examples 1 and 2 have a herringbone structure in the molecular layer as shown in FIGS. 4 and 5, but the molecular orientation is staggered along the a-axis direction in the layer. It turns out that it takes the structure which becomes. That is, the compounds of Examples 1 and 2 cause a change in the transfer integral between molecules in the molecular layer due to a decrease in the interaction between alkyl chains between molecules, and crystals different from the compounds of Comparative Examples 1, 3, and 5 It turns out that it takes a form.

  The crystal structures of the compounds of Examples 1 and 2 are such that the interplanar distance between the BTBT skeletons changes due to a decrease in the interaction between the alkyl chains (reduction of the fastener effect), and the relationship between them. It is thought that the interaction decreases, resulting in a decrease in the cohesive force of the molecules and an increase in solubility and thermal stability.

[Calorimetric analysis]
The compound 1 obtained in Example 4 was subjected to differential thermal / thermogravimetric analysis using a differential thermal / thermogravimetric analyzer (TG / DTA) to obtain a differential thermal / thermogravimetric change curve. The differential heat / thermogravimetric change curve of Compound 1 obtained in Example 4 is shown in FIG.

  The compounds 1 to 4, 6, 18, 26, 32, and 101 to 106 obtained in Examples 1 to 8 and Comparative Examples 1 to 6 were subjected to differential scanning calorimetry using a differential scanning calorimeter (DSC). A differential scanning calorimetry curve (DSC curve) was obtained. The differential scanning calorimetry curves of the compounds 2 to 4, 6, 18, 26, 32, and 101 to 106 obtained in Examples 1 to 3 and 5 to 8 and Comparative Examples 1 to 6 are shown in FIGS.

  Moreover, the differential heat / thermogravimetric change curve of Compound 1 obtained in Example 4 and Examples 1 to 3, 5 to 8 and Compounds 2 to 4, 6, 18, and 26 obtained in Comparative Examples 1 to 6 were used. , 32, and 101-106 DSC curves, the temperature and melting point at which the crystalline phase first undergoes phase transition are shown in the table below.

  7 to 9, “C1”, “C2”, “C3”, “C4”, “C5”, “C6”, “C7”, “C8”, “C9”, and “C10” are implemented, respectively. Corresponding to the compounds of Examples 4, 3, 2, 1, and Comparative Examples 6, 5, 4, 3, 2, 1, “Ph-BTBT-iBu”, “2Nap-BTBT-C4”, “pTol-BTBT-C4” "And" mTol-BTBT-C4 "correspond to the compounds of Examples 5, 6, 7, and 8, respectively. 7 to 9, “K” represents a crystalline phase, “SmE” represents a smectic E phase, “SmA” represents a smectic A phase, and “Iso.Liq.” Represents an isotropic liquid phase. To express.

  As shown in FIGS. 7 and 8, the compounds of Comparative Examples 1 to 6, in the heating process in differential scanning calorimetry, from the crystal phase to the smectic E phase, from the smectic E phase to the smectic A phase, from the smectic A phase, etc. The phase transition to the isotropic liquid phase showed liquid crystallinity. Further, in the compounds of Comparative Examples 1 to 6, a peak indicating a phase transition from the crystal phase to the smectic E phase was observed at less than 170 ° C. (144 to 167 ° C.) in the differential scanning calorimetry curve of the heating process.

  On the other hand, in the compounds of Examples 1 to 3, 5, and 8, as shown in FIGS. 7 and 9, only a peak showing a phase transition was observed at 194 ° C. or higher in the heating process in the differential scanning calorimetry. In the differential scanning calorimetry curve, no peak showing a phase transition was observed below 170 ° C., and the phase transition directly from the crystal phase to the isotropic liquid phase did not show liquid crystallinity. In the compound of Example 4 as well, only a peak indicating phase transition was observed at 194 ° C. or higher in the heating process in differential scanning calorimetry, and a peak indicating phase transition was observed below 170 ° C. in the differential scanning calorimetry curve. In addition, the phase transition directly from the crystal phase to the isotropic liquid phase did not show liquid crystallinity. In the compounds of Examples 6 and 7, although a peak indicating a liquid crystal transition point was observed in the differential scanning calorimetry curve of the heating process, both had a temperature at which the crystal phase first undergoes a phase transition of 171 ° C. or higher, and 170 ° C. A peak showing a phase transition was not observed below, indicating a higher transition temperature than the compounds of Comparative Examples 1-6.

  Therefore, it was found that the compounds of Examples 1 to 8 had significantly higher thermal stability than the compounds of Comparative Examples 1 to 6.

[Measurement of solubility of target compound]
Chloroform was added at a temperature of 25 ° C. until 10 mg of the solute (target compound) was completely dissolved, and the solubility (mg / mL) in chloroform was determined from the volume of the added chloroform. The measurement results of the solubility in chloroform of the target compounds 1 to 4, 6, 26, 32 and 100 to 106 obtained in Examples 1 to 4, 5, 7, and 8 and Comparative Examples 1 to 7 are shown in the following table.

From the results in Table 4, the compounds 1 to 4, 6, 26, and 32 of Examples 1 to 4, 5, 7, and 8 in which R ³ in the general formula (1) is a C1 to C4 alkyl group have solubility in chloroform. Was 3.5 mg / mL or more, the solubility in an organic solvent was high, and the solubility was significantly higher than that of the compound 106 of Comparative Example 1 in which R ³ is a C10 alkyl group.

[Production and evaluation of organic thin-film transistors]
In the following Examples and Comparative Examples, organic thin film transistors were manufactured and evaluated using Compounds 1 to 4 obtained in Examples 1 to 4 and Compounds 101 and 106 obtained in Comparative Examples 8 and 9.

[Example 9] (Production and evaluation of organic thin film transistor 10A using compound 4 obtained in Example 1 (see FIG. 1A))
A p-doped silicon wafer (surface resistance 0 .0) having a SiO ₂ thermal oxide film (insulator layer 4 in FIG. 1A) having a film thickness of 100 nm on one surface and a shadow mask for electrode formation attached on the other surface. 02Ω · cm or less, which also serves as the gate electrode 5 and the substrate 6 in FIG. 1 (a)) is placed in a vacuum deposition apparatus, and exhausted until the degree of vacuum in the apparatus becomes 2.0 × 10 ⁻⁴ Pa or less, By depositing chromium and gold on a p-doped silicon wafer (hereinafter referred to as “substrate”) through a shadow mask for electrode formation by resistance heating vapor deposition, a 1 nm thick chromium electrode or source electrode (FIG. 1A) A source electrode 1) and a gold electrode having a thickness of 15 nm, that is, a drain electrode (drain electrode 3 in FIG. 1A) are formed on a substrate, and a shadow mask for forming an electrode is formed. Removed.

  Next, this substrate is cleaned for 10 minutes using a UV / ozone cleaning machine (model: SSP16-110, manufactured by Sen Special Light Source Co., Ltd.), and then on the surface of the substrate on which the source and drain electrodes are formed. In addition, an about 2 wt% chlorobenzene saturated solution of the compound 4 obtained in Example 1 as an organic semiconductor material containing an organic solvent was applied by spin coating at 100 ° C., and then chlorobenzene was dried. The organic semiconductor thin film (semiconductor layer 2 in FIG. 1A) was formed on the surface of the substrate on which the source and drain electrodes are formed. As a result, a bottom gate-bottom contact type organic thin film transistor (channel length 50 μm, channel width 350 μm) according to an example of the present invention was obtained.

  The obtained organic thin-film transistor was installed in a prober, and semiconductor characteristics were measured using a semiconductor parameter analyzer (model: E5270A, manufactured by Agilent Technologies).

FIG. 10 is a graph showing the semiconductor characteristics of the organic thin film transistor according to the present embodiment. The drain voltage is fixed to −40V which is a saturation region, the gate voltage is scanned from 10V to −50V, and the drain voltage−gate voltage ( The results of measuring transfer characteristics are shown. Specifically, the horizontal axis represents the gate voltage (Vg (V)), the vertical axis represents the absolute value of the drain current (| Id | (A); right end scale), and the square root of the absolute value of the drain current (| Id). | ^1/2 (A ^1/2 ); left end scale) is a graph showing the characteristics of the organic thin film transistor prepared in Example 9.

  From the measurement results shown in FIG. 10, the threshold voltage was obtained as a numerical value indicating the semiconductor characteristics of the organic thin film transistor prepared in Example 9. The method for obtaining each numerical value indicating the semiconductor characteristics is as follows.

<Threshold voltage>
In the graph showing the relationship between the gate voltage (Vg (V)) shown in FIG. 10 and the square root of the absolute value of the drain current (| Id | ^1/2 (A ^1/2 )), the slope can be regarded as substantially constant. The range was approximated by a straight line, and the voltage value at a point where a straight line obtained by extrapolating the approximate line intersects the X axis (a point where Id = 0A) was obtained.

<Carrier mobility>
Since the drain current-gate voltage characteristics in the saturation region are expressed by the following formula (a), the carrier mobility was calculated using the formula (a).
Id = (1/2) WμCp (Vg−Vth) ² / L Expression (a)
Where Id: drain current
W: Channel width
μ: Carrier mobility
Cp: Capacitance of the insulator layer 4
Vg: Gate voltage
Vth: threshold voltage
L: Channel length

In this measurement, the channel width W is 350 μm, the capacitance of the insulator layer 4 is 33.5 × 10 ⁻⁸ F, and the channel length L is 50 μm. Further, the gate voltage Vg was set to −40 V which becomes a saturation region.

From the above measurements and calculations, the carrier mobility of the organic thin film transistor obtained in Example 9 was 9.0 × 10 ⁻² cm ² / Vs, and the threshold voltage was 1.7V. These results are shown in Table 5. The carrier mobility and the threshold voltage were calculated in the same manner for Examples 10 to 12, Example 7 and Example 8 described later.

[Example 10] (Production and evaluation of organic thin film transistor 10A using compound 3 obtained in Example 2 (see FIG. 1A))
An organic thin film transistor according to an example of the present invention was obtained in the same manner as in Example 9, except that the compound 4 obtained in Example 1 was changed to the compound 3 obtained in Example 2. Furthermore, the characteristics of the organic thin film transistor were examined by the method described in Example 9, and the results are shown in Table 5.

[Example 11] (Production and Evaluation of Organic Thin Film Transistor 10A Using Compound 2 Obtained in Example 3 (see FIG. 1A))
An organic thin film transistor according to an example of the present invention was obtained in the same manner as in Example 9, except that the compound 4 obtained in Example 1 was changed to the compound 2 obtained in Example 3. Furthermore, the characteristics of the organic thin film transistor were examined by the method described in Example 9, and the results are shown in Table 5.

[Example 12] (Production and evaluation of organic thin film transistor 10A using compound 1 obtained in Example 4 (see FIG. 1A))
An organic thin film transistor according to an example of the present invention was obtained in the same manner as in Example 9, except that the compound 4 obtained in Example 1 was changed to the compound 1 obtained in Example 4. Furthermore, the characteristics of the organic thin film transistor were examined by the method described in Example 9, and the results are shown in Table 5.

[Comparative Example 8] (Production and Evaluation of Organic Thin Film Transistor 10A Using Compound 101 Obtained in Comparative Example 6 (see FIG. 1A))
A comparative organic thin film transistor was obtained in the same manner as in Example 9, except that the compound 4 obtained in Example 1 was changed to the compound 101 obtained in Comparative Example 6. Furthermore, the characteristics of the organic thin film transistor were examined by the method described in Example 9, and the results are shown in Table 5.

[Comparative Example 9] (Production and Evaluation of Organic Thin Film Transistor 10A Using Compound 106 Obtained in Comparative Example 1 (see FIG. 1A))
A comparative organic thin film transistor was obtained in the same manner as in Example 9, except that the compound 4 obtained in Example 1 was changed to the compound 106 obtained in Comparative Example 1. Furthermore, the characteristics of the organic thin film transistor were examined by the method described in Example 9, and the results are shown in Table 5.

  From Table 5, the organic thin-film transistors of Examples 9 to 12 using the compounds of Examples 1 to 4 exhibit superior transistor characteristics than the organic thin-film transistors of Comparative Examples 8 and 9 using the compounds of Comparative Examples 1 and 6. I understood.

  The condensed polycyclic aromatic compound and the organic semiconductor thin film of the present invention can be suitably used as a component of an organic semiconductor device. The organic semiconductor device of the present invention can be used in the fields of organic thin film transistors, diodes, capacitors, thin film photoelectric conversion devices, dye-sensitized solar cells, organic EL devices, and the like.

DESCRIPTION OF SYMBOLS 1 Source electrode 2 Semiconductor layer 3 Drain electrode 4 Insulator layer 5 Gate electrode 6 Substrate 7 Protective layer 10A-10F Organic thin-film transistor 20 Organic solar cell device 21 Substrate 22 Anode 23 Power generation layer 24 Cathode 231 P-type layer 232 N-type layer 233 Buffer layer

Claims (8)

The following general formula (1)

(In the formula, R ¹ represents an aryl group, R ² represents a hydrogen atom, R ³ represents an alkyl group having 1 to 4 carbon atoms, R ⁴ represents a hydrogen atom, and X ¹ and X ² are each independent. Represents a sulfur atom, a selenium atom, or a tellurium atom)
A condensed polycyclic aromatic compound represented by the formula: The condensed polycyclic aromatic compound according to claim 1,
A condensed polycyclic aromatic compound, which is a compound in which no peak showing a phase transition is observed below 170 ° C. in a differential scanning calorimetry curve. The condensed polycyclic aromatic compound according to claim 1 or 2,
A condensed polycyclic aromatic compound characterized by not exhibiting liquid crystallinity. At least one condensed polycyclic aromatic compound according to any one of claims 1 to 3,
An organic semiconductor material comprising an organic solvent.   An organic semiconductor thin film comprising the condensed polycyclic aromatic compound according to any one of claims 1 to 3. A method for forming an organic semiconductor thin film according to claim 5, comprising:
A method for forming an organic semiconductor thin film, comprising: applying or printing the organic semiconductor material according to claim 4 on a surface on which an organic semiconductor thin film is to be formed, and drying an organic solvent.   An organic semiconductor device comprising the organic semiconductor thin film according to claim 5. The organic semiconductor device according to claim 7,
An organic semiconductor device characterized by being an organic thin film transistor.

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