JP2016001659A - Organic semiconductor material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic semiconductor material containing a sulfur-containing condensed ring compound applicable to an organic transistor, an organic light-emitting diode, an organic laser, a flexible display, a multifunctional switch, a multifunctional sensor, an organic thin film solar cell and an organic memory.SOLUTION: An organic semiconductor material has a condensed ring skeleton of asymmetric structure shown by a following general formula (8) (n is an integer of 1-5, and Y is a functional group having a specific ring structure).

Description

  The present invention relates to an organic semiconductor material containing a sulfur-containing fused ring compound.

  Since organic semiconductor materials are expected to be applied to organic semiconductor devices such as flexible displays, multifunction switches, multifunction sensors, and organic solar cells, they have been actively studied in recent years. Oligoacene is known as one of such organic semiconductor materials. Oligoacene is a compound in which a plurality of benzene rings are condensed in a straight chain, and has the property that the energy difference between HOMO and LUMO decreases as the number of condensed rings increases. Therefore, among oligoacenes, oligoacenes having a condensed ring number of 5 or more, such as pentacene and hexacene, are attracting particular attention as organic semiconductor materials that can be expected to have high mobility.

  Patent Document 1 discloses an organic semiconductor material made of a sulfur-containing fused ring compound. Since the sulfur atom is an atom having a higher electronegativity than the carbon atom, introduction into the molecule can reduce the HOMO and improve the air stability of the molecule. The sulfur atom introduced into the molecule forms an intermolecular SS contact or an S-π contact that easily causes an interaction between molecular orbitals. Since each of these contacts becomes a path for electrons and holes superior to the π-π contact, an improvement in mobility can be expected.

JP 2012-169550 A

  This invention has been made based on the finding that a sulfur-containing fused ring compound having a specific structure is useful as an organic semiconductor material as a result of intensive studies by the present researchers. The purpose is to provide a novel organic semiconductor material.

  The organic semiconductor material for achieving the above object contains a sulfur-containing condensed ring compound having a condensed ring skeleton having 5 to 9 condensed rings represented by the following general formula (1).

(X is a condensed ring formed by combining one or more of the units represented by the following general formulas (2) to (4), and Y is a functional group represented by the following general formulas (5) to (7). One of them.)

(“·” Indicates the condensation position.)

(R is a hydrocarbon group having 1 to 100 carbon atoms.)
The organic semiconductor material for achieving the above object contains a sulfur-containing fused ring compound having a fused ring skeleton represented by the following general formula (8).

(N is an integer of 1 to 5, and Y is any one of the functional groups represented by the following general formulas (5) to (7).)

(R is a hydrocarbon group having 1 to 100 carbon atoms.)
In the organic semiconductor material, the condensed ring skeleton includes a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an alkyloxycarbonyl group, and an aryloxycarbonyl group. Carboxyl group, formyl group, hydroxyl group, amino group, cyano group, silyl group, mercapto group, sulfonyl group, cycloalkyl group, cycloalkenyl group, alkylthio group, ester group, imino group, amide group, sulfide group, disulfide group, In addition, it is preferable that the same or different functional groups selected from composite functional groups containing two or more of these groups are bonded.

  According to the present invention, a novel organic semiconductor material is provided.

Explanatory drawing of the organic field effect transistor in an Example.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail.
The organic semiconductor material of the present embodiment contains a specific sulfur-containing fused ring compound, and this sulfur-containing fused ring compound will be described below.

  The sulfur-containing fused ring compound has a fused ring skeleton having 5 to 9 fused rings represented by the following general formula (1).

In the above general formula (1), X is a unit represented by the following general formula (2) (benzene unit), a unit represented by the following general formula (3) (benzothiophene unit), and the following general formula (4). It is a condensed ring formed by combining one or more of the units shown (benzothienothiophene units). In the following general formulas (2) to (4), “•” indicates a condensation position.

The directions of the units represented by the general formula (3) and the following general formula (4) are not particularly limited. As an example of the condensed ring skeleton of the sulfur-containing condensed ring compound, a condensed ring skeleton in the case where the number of condensed rings is 6 is shown below.

Among the condensed ring skeletons represented by the above general formula (1), it is preferable that the condensed ring portion has an asymmetric structure, and in particular, the condensed X consists only of the units (benzene units) represented by the above general formula (2). A ring skeleton, that is, a condensed ring skeleton represented by the following general formula (8) is preferable. In addition, n in the following general formula (8) is an integer of 1 to 5.

Here, the condensed ring portion having an asymmetric structure means that there is no axis of symmetry and no symmetry point in the molecular structure of the condensed ring portion, that is, the condensed ring portion does not have a line-symmetric or point-symmetric molecular structure. To do. By making the fused ring portion an asymmetric structure, the solubility of the sulfur-containing fused ring compound is improved.

  In the condensed ring skeleton represented by the general formula (1), the functional group Y is any one of the functional groups represented by the following general formulas (5) to (7).

In the general formulas (5) to (7), R is a hydrocarbon group having 1 to 100 carbon atoms, preferably a hydrocarbon group having 1 to 16 carbon atoms, and more preferably a carbon group having 6 to 16 carbon atoms. It is a hydrogen group. Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an aryl group, and an aralkyl group. Examples of the alkyl group include linear alkyl groups such as methyl group, ethyl group, n-propyl group, and n-butyl group, isobutyl group, isodecyl group, 2-ethylhexyl group, 2-ethylbutyl group, and 2-octyl- Examples thereof include branched alkyl groups such as dodecyl group, neopentyl group and t-butyl group, and cyclic alkyl groups such as cyclohexyl group, cyclopentyl group and cyclopropyl group. Examples of the alkenyl group include an allyl group, a homoallyl group, and a butenyl group. In addition, the bonding position of R in each ring structure of a thiophene ring, a benzene ring, and a pyridine ring is not particularly limited, but is preferably bonded to the 2-position.

  In the sulfur-containing condensed ring compound, the condensed ring skeleton represented by the general formula (1) (including the functional group represented by Y) includes a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, Alkoxy group, aryloxy group, acyl group, alkyloxycarbonyl group, aryloxycarbonyl group, carboxyl group, formyl group, hydroxyl group, amino group, cyano group, silyl group, mercapto group, sulfonyl group, cycloalkyl group, cycloalkenyl group , An alkylthio group, an ester group, an imino group, an amide group, a sulfide group, a disulfide group, and the same or different functional group selected from a composite functional group containing two or more of these groups.

  The functional group will be specifically described. As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example. The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, for example, methyl group, ethyl group, n-propyl group, n-butyl group, t-butyl group, n-hexyl group, trifluoro group. A methyl group and a benzyl group are mentioned. As said alkenyl group, it is preferable that it is a C1-C10 alkenyl group, for example, a methacryl group and an acryl group are mentioned. As said alkynyl group, it is preferable that it is a C1-C10 alkynyl group, for example, an ethynyl group and a propynyl group are mentioned. In the alkenyl group and alkynyl group, the double bond and triple bond may be located at any position in the functional group.

  Examples of the aryl group include a phenyl group, a p-tolyl group, a p-fluorophenyl group, and a pentafluorophenyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a 2-methoxyethoxy group, and a t-butoxy group. Examples of the aryloxy group include a phenoxy group and a 4-methylphenoxy group. Examples of the acyl group include a 2-methylpropanoyl group, a cyclohexylcarbonyl group, an octanoyl group, a chloroacetyl group, a trifluoroacetyl group, and a benzoyl group.

  Examples of the alkyloxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, and a t-butoxycarbonyl group. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group and a 2-hydroxymethylphenoxycarbonyl group.

  Examples of the amino group include an amino group, a dimethylamino group, a methylphenylamino group, and a phenylamino group. Examples of the silyl group include a trimethylsilyl group and a dimethylphenylsilyl group. Examples of the sulfonyl group include an n-butylsulfonyl group, an n-octylsulfonyl group, and a phenylsulfonyl group.

  Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. Examples of the cycloalkenyl group include a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, and a cyclohexenyl group. Examples of the alkylthio group include a methylthio group, an ethylthio group, and a propylthio group. Examples of the composite functional group include a 2-hydroxy-1-propenyl group, a hydroxyethoxyethyl group, a hydroxyethylthioethyl group, and a dimethylaminocarbonyl group.

Next, the manufacturing method of the said sulfur-containing condensed ring compound is demonstrated.
The sulfur-containing fused ring compound can be synthesized, for example, by adding a functional group Y after synthesizing a compound that becomes a fused ring portion. Specifically, after performing a Friedel-Crafts reaction using thienothiophene or a derivative thereof and a carboxylic acid anhydride such as acene dicarboxylic acid anhydride or benzothiophene dicarboxylic acid anhydride, a known method is used. By performing a heterocyclization reaction, a compound that becomes the fused ring portion can be synthesized (see, for example, Patent Document 1). Then, after performing lithiation at the 2-position of the thienothiophene moiety with n-butyllithium and treatment with trimethyltin chloride, a still coupling reaction with a compound such as 2-bromooctylthiophene is performed, whereby the above sulfur-containing compound A fused ring compound can be synthesized. The sulfur-containing fused ring compound can be highly purified by synthesizing using the above method and then purifying using a known purification method such as a sublimation method or a recrystallization method.

  Since the sulfur-containing fused ring compound has characteristics as a semiconductor, it can be applied to an organic semiconductor device as an organic semiconductor material. Examples of the organic semiconductor device include an organic transistor, an organic light emitting diode, an organic laser, a flexible display, a multifunction switch, a multifunction sensor, an organic thin film solar cell, and an organic memory.

  When the organic semiconductor material containing the sulfur-containing fused ring compound is applied to an organic semiconductor device, the material is used in the form of a thin film. At this time, since the sulfur-containing fused ring compound has high solubility in a solvent such as an organic solvent, a wet process (eg, spin coating method, dip coating method, bar coating method, spray coating method, ink jet method, screen printing method, It is possible to form a thin film of an organic semiconductor material by adopting a coating method such as a lithographic printing method, an intaglio printing method, and a relief printing method. Examples of the organic solvent include dichloromethane, chloroform, chlorobenzene, cyclohexanol, toluene, xylene, nitrobenzene, methyl ethyl ketone, diglyme, and tetrahydrofuran.

Next, the effect in this embodiment will be described below.
(1) The organic semiconductor material of the present embodiment contains a sulfur-containing fused ring compound having a fused ring skeleton having 5 to 9 fused rings represented by the general formula (1). Since the organic semiconductor material of this embodiment is excellent in transistor characteristics, it can be suitably applied to an organic semiconductor device.

  (2) Since the organic semiconductor material of the present embodiment has high solubility in a solvent such as an organic solvent, a wet process can be employed when applied to an organic semiconductor device. Therefore, the cost for manufacturing the organic semiconductor device can be reduced.

In addition, this embodiment can also be changed and embodied as follows.
In the organic semiconductor material, it is possible to include various components known in the organic semiconductor material that are components other than the sulfur-containing fused ring compound.

Hereinafter, examples that further embody the above embodiment will be described.
[1. Synthesis of Example 1 and Example 2]

Under a nitrogen atmosphere, anthracenothienothiophene (203.5 mg) was dissolved in tetrahydrofuran (120 mL) in a 200 mL three-necked flask, and then n-butyllithium (0.875 mL) was added and stirred at room temperature for 2 hours. Thereafter, the reaction solution was cooled to −78 ° C., and a tetrahydrofuran solution of trimethyltin chloride (135 mg / 15 mL) was added dropwise over 1 hour. The reaction solution was gradually warmed and stirred at room temperature for 16 hours. The reaction mixture was cooled using an ice bath, saturated sodium hydrogen carbonate (80 mL) was added, and the mixture was stirred for 30 min. After the solvent was distilled off from the filtrate obtained by filtering the reaction liquid, extraction with ether gave brown compound 1 (293.7 mg).

Compound 1 (274.9 mg) was dissolved in toluene (120 mL) in a 200 mL three-necked flask under a nitrogen atmosphere, and then 2-bromo5-n-octylthiophene (166.8 mg), Pd (PPh ₃ ) ₄ ( 42.1 mg) was added and the mixture was stirred with heating for 16 hours. After the reaction solution was allowed to cool to room temperature, the precipitated orange solid was collected by suction filtration, and purified by sublimation to obtain Compound 2 (145 mg). The measurement result of ¹ H-NMR of the obtained compound 2 is shown below. This compound 2 was defined as Example 1.

¹ H NMR (CDCl ₃ , 500 MHz) δ 8.58 (s, 1H), 8.48 (s, 1H), 8.45 (s, 1H), 8.39 (s, 1H), 8.03-8 .02 (m, 2H), 7.46-7.45 (m, 2H), 7.31 (s, 1H), 7.14 (d, J = 3.40 Hz, 1H), 6.75 (d , J = 3.40 Hz, 1H), 2.84 (t, J = 7.65 Hz, 2H), 1.72 (quin., J = 7.66 Hz, 2H), 1.46-1.20 (m , 10H), 0.90 (t, J = 6.80 Hz, 3H).

Compound 1 (198.0 mg) was dissolved in toluene (80 mL) in a 200 mL three-necked flask under a nitrogen atmosphere, and then 2-bromo5-n-dodecylthiophene (144.8 mg), Pd (PPh ₃ ) ₄ ( 30.3 mg) was added and stirred with heating for 16 hours. After the reaction solution was allowed to cool to room temperature, the precipitated orange solid was collected by suction filtration. The collected orange solid was dissolved in toluene (150 mL) with heating, and the filtrate was collected by suction filtration. The filtrate was allowed to cool to room temperature, and the precipitated orange solid was collected by filtration to obtain Compound 3 (59.7 mg). The measurement result of ¹ H-NMR of the obtained compound 3 is shown below. This compound 3 was defined as Example 2.

¹ H NMR (CDCl ₃ , 500 MHz) δ 8.58 (s, 1H), 8.48 (s, 1H), 8.45 (s, 1H), 8.39 (s, 1H), 8.03-8 .02 (m, 2H), 7.46-7.45 (m, 2H), 7.31 (s, 1H), 7.14 (d, J = 3.40 Hz, 1H), 6.75 (d , J = 3.40 Hz, 1H), 2.83 (t, J = 7.37 Hz, 2H), 1.72 (quin., J = 7.66 Hz, 2H), 1.43-1.22 (m , 16H), 0.88 (t, J = 6.80 Hz, 3H).
[2. Evaluation of solubility]
Example 1 showed a solubility of 1480 mg / mL in hot chloroform. In addition, Example 2 showed 1650 mg / mL solubility in hot chloroform. The solubility exceeding 1000 ppm is the solubility that enables the production of an organic semiconductor device by a wet process.

[3. Fabrication and evaluation of organic semiconductor devices]
(Dry process)
Using Example 1, an organic field effect transistor having a bottom gate-top contact structure shown in FIG. 1 was fabricated by a dry process. The electrode using gold, vacuum deposition SiO 2 / _Si substrate surface treated with polystyrene: to produce an organic thin film layer formed in Examples 1 to (substrate temperature room temperature). The organic field effect transistor has a channel length of 75 μm and a channel width of 1000 μm. For comparison, a similar organic field effect transistor having an organic thin film layer made of anthracenothienothiophene (ATT) was produced.

As a result of evaluating the characteristics of each organic field effect transistor, the organic thin film layer of Example 1 has a mobility of 0.68 to 1.94 cm ² V ⁻¹ s ⁻¹ and a p-type characteristic having a very high value. showed that. In contrast, the organic thin film layer made of ATT has a mobility of 5.99 × 10 ^{−3 to} 2.37 × 10 ⁻² cm ² V ⁻¹ s ⁻¹ , and Example 1 is more organic than ATT. It was found that the field effect transistor characteristics were excellent. Note that the mobility exceeding ¹ cm ² V ⁻¹ s ⁻¹ is a value comparable to the mobility of amorphous silicon capable of driving a liquid crystal television.

(Wet process)
Using Example 1 and Example 2, an organic field effect transistor having a bottom gate-top contact type structure shown in FIG. 1 was fabricated by a wet process. Implemented by spin coating (solution concentration: 0.1 wt%, solvent: chloroform, rotation speed: 4000 rpm, substrate temperature: 150 ° C.) on a SiO ₂ / Si substrate surface-treated with crosslinked polyvinylphenol using gold as the electrode The organic thin film layer which consists of Example 1 or Example 2 was produced. The organic field effect transistor has a channel length of 75 μm and a channel width of 2000 μm.

As a result of evaluating the characteristics of each organic field effect transistor, the organic thin film layer of Example 1 has a mobility of 4.32 × 10 ^{−3 to} 8.57 × 10 ⁻² cm ² V ⁻¹ s ⁻¹ . The mobility of the organic thin film layer of Example 2 was 4.60 × 10 ^{−3 to} 1.29 × 10 ⁻² cm ² V ⁻¹ s ⁻¹ . These values are values that are an order of magnitude higher than those of an organic thin film layer made of ATT prepared by vacuum deposition.

Claims (3)

An organic semiconductor material containing a sulfur-containing fused ring compound having a fused ring skeleton having 5 to 9 fused rings represented by the following general formula (1).
(X is a condensed ring formed by combining one or more of the units represented by the following general formulas (2) to (4), and Y is a functional group represented by the following general formulas (5) to (7). One of them.)
(“·” Indicates the condensation position.)
(R is a hydrocarbon group having 1 to 100 carbon atoms.) An organic semiconductor material containing a sulfur-containing fused ring compound having a fused ring skeleton represented by the following general formula (8).
(N is an integer of 1 to 5, and Y is any one of the functional groups represented by the following general formulas (5) to (7).)
(R is a hydrocarbon group having 1 to 100 carbon atoms.)   The condensed ring skeleton includes a hydrogen atom, a halogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, an acyl group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a carboxyl group, and a formyl group. , Hydroxyl group, amino group, cyano group, silyl group, mercapto group, sulfonyl group, cycloalkyl group, cycloalkenyl group, alkylthio group, ester group, imino group, amide group, sulfide group, disulfide group, and two of these The organic semiconductor material according to claim 1 or 2, wherein the same or different functional groups selected from composite functional groups containing the above groups are bonded.