JP7494456B2 - Biphenylene derivative, organic semiconductor layer, and organic thin film transistor - Google Patents

Description

The present invention relates to a novel biphenylene derivative that can be used in electronic materials such as organic semiconductor materials, an organic semiconductor layer using the same, and an organic thin-film transistor, and in particular to a novel biphenylene derivative that has excellent mobility and solubility and can be applied to various device fabrication processes, an organic semiconductor layer using the same, and an organic thin-film transistor.

Organic semiconductor devices, such as organic thin-film transistors, have been attracting attention in recent years because they offer features not found in inorganic semiconductor devices, such as energy saving, low cost, and flexibility. These organic semiconductor devices are composed of several types of materials, such as an organic semiconductor layer, a substrate, an insulating layer, and electrodes, and among these, the organic semiconductor layer, which is responsible for the movement of charge carriers, plays a central role in the device. Since the performance of organic semiconductor devices depends on the carrier mobility of the organic semiconductor material that composes this organic semiconductor layer, the emergence of organic semiconductor materials that provide high carrier mobility is desired.

Commonly known methods for producing organic semiconductor layers include the vacuum deposition method, in which organic materials are vaporized under high temperature and vacuum, and the coating method, in which an organic material is dissolved in a suitable solvent and the solution is coated. Of these, the coating method can also be carried out using printing technology without using high temperature and high vacuum conditions. Therefore, it is expected that the manufacturing costs of device production will be significantly reduced, making it an economically preferable process.

From the viewpoint of the device fabrication process, the organic semiconductor material used in such a coating method preferably has a carrier mobility of 0.1 cm ² /V·sec or more and a solubility of 0.1 wt % or more at room temperature.

Here, it is generally known that small molecule semiconductors with a rod-shaped molecular long axis of a fused ring system tend to exhibit high carrier mobility because they have higher crystallinity than polymer semiconductors. However, when the number of fused rings is 5 or less, there is an issue of low melting point, while when the number of fused rings is 6 or more, there is an issue of low solubility. At present, there are almost no known small molecule organic semiconductor materials that combine high carrier mobility, high heat resistance, and appropriate solubility.

Currently, low molecular weight materials that have been proposed include 2,7-dialkyl-substituted benzothienobenzothiophene (fused 4 rings) (see, for example, Patent Document 1 and Non-Patent Document 1), 6,6'-dialkyldinaphthothienothiophene (fused 6 rings) (see, for example, Patent Document 2), and terphenylene derivatives (see, for example, Patent Document 3).

However, in the case of the dialkyl-substituted benzothienobenzothiophene described in Patent Document 1 and Non-Patent Document 1, there was a problem in that the transistor operation was lost when heated to 130°C or higher.

The 6,6'-dialkyldinaphthothienothiophene described in Patent Document 2 has a problem in that its solubility at 60°C is low, at 0.08 g/L or less (0.01% by weight or less, toluene).

Furthermore, the terphenylene derivative described in Patent Document 3 has a highly linear fused ring structure consisting of a benzene ring and a cyclobutene ring, which reduces the solubility.

Patent Document 1: WO2008/047896 Patent Document 1: WO2010/098372 Patent Document 1: WO2006/109569

Journal of American Chemical Society, 2007, Vol. 129, pp. 15732-15733

The present invention was made in consideration of the above problems, and its purpose is to provide a new coating-type organic semiconductor material that combines high carrier mobility, high heat resistance, and appropriate solubility, and does not deteriorate in transistor operation performance even when exposed to an atmosphere of 130°C or higher.

As a result of intensive research to solve the above problems, the inventors discovered that a novel biphenylene derivative provides high carrier mobility, as well as high heat resistance and suitable solubility, and retains mobility even after heat treatment, resulting in an organic semiconductor material with significantly improved switching characteristics, and thus completed the present invention.

That is, the present invention relates to a biphenylene derivative characterized by the following general formula (1), an organic semiconductor layer, and an organic thin-film transistor using the same.

[(Here, A represents one of the group consisting of a covalent bond, oxygen, sulfur, and selenium, and one of the combinations of adjacent two of R ¹ to R ⁴ and one of the combinations of adjacent two of R ⁵ to R ⁸ constitute the following general formula (2) to form a 4- to 6-membered ring. R ¹ to R ⁸ that do not constitute the following general formula (2) each independently represent one of the group consisting of hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or an aryl group having 4 to 26 carbon atoms, and the hydrogen of the alkyl group, alkenyl group, alkynyl group, or aryl group may be substituted with fluorine.)

(wherein X represents one of the group consisting of a covalent bond, oxygen, sulfur, selenium, CR ¹⁰ ═CR ¹¹ , or NR ¹² ; Y represents CR ¹³ or nitrogen; n represents 1 or 2; R ⁹ to R ¹³ each independently represent one of the group consisting of a hydrogen, a halogen, a fluorine-substituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or a heteroaryl-2-group having 5 to 26 carbon atoms and a substituent at the 4th position, at least one of R ⁹ to R ¹³ is a fluorine-substituted alkyl group having 1 to 20 carbon atoms or a heteroaryl-2-group having 4 to 26 carbon atoms and a substituent at the 4th position, and the hydrogen of the substituent at the 4th position of the alkenyl group, alkynyl group, or heteroaryl-2-group may be substituted with fluorine.)

In the above general formula (1), A represents a covalent bond, oxygen, sulfur, or selenium, and is preferably a covalent bond, oxygen, or sulfur since it results in a biphenylene derivative exhibiting high mobility. In the above general formula (1), the halogen in R ¹ to R ⁸ represents, for example, one of the group consisting of fluorine, chlorine, bromine, and iodine, and is preferably fluorine since it is stable.

In the above general formula (1), examples of the alkyl group having 1 to 20 carbon atoms for R ¹ to R ⁸ include one selected from the group consisting of straight-chain, branched, or cyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isovaleryl, n-hexyl, isohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-octadecyl, 2-ethylhexyl, 3-ethylheptyl, 3-ethyldecyl, 2-hexyldecyl, cyclopentyl, cyclohexyl, and cycloheptyl. Among these, an alkyl group having 1 to 14 carbon atoms is preferred, since it results in a biphenylene derivative exhibiting particularly high mobility and high solubility, and more preferred is one selected from the group consisting of linear alkyl groups having 1 to 14 carbon atoms, which are methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-dodecyl group, and n-tetradecyl group.
In addition, in the alkyl group having 1 to 20 carbon atoms, at least one hydrogen can be substituted with a fluorine.

In the above general formula (1), examples of the alkenyl group having 2 to 20 carbon atoms for R ¹ to R ⁸ include one selected from the group consisting of ethenyl, n-propenyl, n-butenyl, 2-methylpropenyl, n-pentenyl, 2-methylbutenyl, n-hexenyl, 2-methylpentenyl, n-heptenyl, n-octenyl, 2-ethylhexenyl, n-nonyl, 2-ethylheptenyl, n-decenyl, n-dodecenyl, cyclopentenyl-1-group, cyclohexenyl-1-group, and cycloheptenyl-1-group.
In addition, in the alkenyl group having 2 to 20 carbon atoms, at least one hydrogen can be substituted with a fluorine.

In the above general formula (1), examples of the alkynyl group having 2 to 20 carbon atoms for R ¹ to R ⁸ include one selected from the group consisting of an ethynyl group, an n-propynyl group, an n-butynyl group, an n-pentynyl group, an n-hexynyl group, an n-heptynyl group, an n-octynyl group, an n-nonynyl group, an n-decynyl group, and an n-dodecynyl group.
In addition, in the alkynyl group having 2 to 20 carbon atoms, at least one hydrogen can be substituted with a fluorine.

In the above general formula (1), the aryl group having 4 to 26 carbon atoms in R ¹ to R ⁸ includes a heteroaryl group having 4 to 24 carbon atoms. For example, there are phenyl groups; alkyl-substituted phenyl groups such as p-tolyl, p-(n-hexyl)phenyl, p-(n-octyl)phenyl, and p-(2-ethylhexyl)phenyl groups; 2-furyl groups, 2-thienyl groups; 5-fluoro-2-furyl groups, 5-methyl-2-furyl groups, 5-ethyl-2-furyl groups, 5-(n-propyl)-2-furyl groups, 5-(n-butyl)-2-furyl groups, 5-(n-pentyl)-2-furyl groups, 5-(n-hexyl)-2-furyl groups, 5-(n-octyl)-2-furyl groups, and the like. [0043] Examples of the alkyl substituted heteroaryl groups include 5-(n-furyl) group, 5-(2-ethylhexyl)-2-furyl group, 5-fluoro-2-thienyl group, 5-methyl-2-thienyl group, 5-ethyl-2-thienyl group, 5-(n-propyl)-2-thienyl group, 5-(n-butyl)-2-thienyl group, 5-(n-pentyl)-2-thienyl group, 5-(n-hexyl)-2-thienyl group, 5-(n-octyl)-2-thienyl group, and 5-(2-ethylhexyl)-2-thienyl group.
In addition, in the aryl group having 4 to 26 carbon atoms, at least one hydrogen atom can be substituted with a fluorine atom.

In the above general formula (1), R ¹ to R ⁸ that do not constitute general formula (2) are preferably one of the group consisting of hydrogen, halogen, and an alkyl group having 1 to 20 carbon atoms, more preferably one of the group consisting of hydrogen, fluorine, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, in order to have high mobility, and particularly preferably hydrogen.

One of the combinations of any two adjacent rings of R ¹ to R ⁴ in the above general formula (1) and one of the combinations of any two adjacent rings of R ⁵ to R ⁸ constitute general formula (2) and can form a 4- to 6-membered ring. Specific examples of the 4- to 6-membered ring include one from the group consisting of a cyclobutene ring, a thiophene ring, a furan ring, a selenophene ring, a thiazole ring, an oxazole ring, a pyrrole ring, an imidazole ring, a benzene ring, and a pyridine ring. In view of high mobility, a ring from the group consisting of a cyclobutene ring, a thiophene ring, a furan ring, a selenophene ring, and a benzene ring is preferred.

In the general formula (1), among the combinations of two adjacent groups among R ¹ to R ⁴ and R ⁵ to R ⁸ , it is preferred that R ¹ and R ² , R ⁵ and R ⁶ , R ¹ and R ² , R ⁷ and R ⁸ , or R ² and R ³ and R ⁶ and R ⁷ constitute the general formula (2) in order to achieve high mobility.

In the general formula (2), X represents one of the group consisting of a covalent bond, oxygen, sulfur, selenium, ^CR10 = ^CR11 , or ^NR12 , and Y represents ^CR13 or nitrogen. For high mobility, it is preferred that X represents one of the group consisting of a covalent bond, oxygen, sulfur, selenium, or ^CR10 = ^CR11 , and Y represents ^CR13 , and it is even more preferred that X represents one of the group consisting of a covalent bond, oxygen, sulfur, or selenium, and Y represents ^CR13 .
When ^R2 and ^R3 , and ^R6 and ^R7 form the general formula (2), X is preferably one of the group consisting of oxygen, sulfur, and selenium for high solubility.

In general formula (2), n is 1 or 2. When n is 2, it means one of the following general formulas (3). For high solubility, n is preferably 1.

In general formula (2), R ⁹ to R ¹³ each independently represent one of the group consisting of hydrogen, halogen, a fluorine-substituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and a heteroaryl-2-group having 5 to 26 carbon atoms and a substituent at the 4th position, at least one of R ⁹ to R ¹³ represents a fluorine-substituted alkyl group having 1 to 20 carbon atoms or a heteroaryl-2-group having 4 to 26 carbon atoms and a substituent at the 4th position, and for high solubility, R ⁹ is preferably one of the group consisting of halogen, a fluorine-substituted alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and a heteroaryl-2-group having 5 to 26 carbon atoms and a substituent at the 4th position. Also, for high mobility and high solubility, R ¹⁰ to R ¹³ are preferably one of the group consisting of hydrogen, fluorine, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group. Hydrogen is particularly preferred due to its high mobility.

Examples of the halogen, alkenyl group having 2 to 20 carbon atoms, and alkynyl group having 2 to 20 carbon atoms of R ⁹ to R ¹³ include the groups shown above for R ¹ to R ^8. In the alkenyl group having 2 to 20 carbon atoms, alkynyl group having 2 to 20 carbon atoms, and heteroaryl-2-group having 5 to 26 carbon atoms and having a substituent at the 4-position, at least one hydrogen can be substituted with a fluorine.

In the general formula (2), examples of the fluorine-substituted alkyl group having 1 to 20 carbon atoms represented by R ⁹ to R ¹³ include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, a hendecafluoropentyl group, a tridecafluorohexyl group, a pentadecafluoroheptyl group, a heptadecafluorooctyl group, a nonadecafluorononyl group, a henicosafluorodecyl group, a triicosafluorohendecyl group, and a pentaicosafluorododecyl group. In view of high solubility, a member of the group consisting of a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, a nonafluorobutyl group, a hendecafluoropentyl group, a tridecafluorohexyl group, a pentadecafluoroheptyl group, and a heptadecafluorooctyl group is preferred.

In the general formula (2), the heteroaryl-2-group having 5 to 26 carbon atoms and having a substituent at the 4-position of R ⁹ to R ¹³ can be, for example, one from the group consisting of 4-hexyl-2-thieno group, 4-heptyl-2-thieno group, 4-octyl-2-thieno group, 4-nonyl-2-thieno group, 4-decyl-2-thieno group, 4-octyl-2-furano group, and 4-tridecafluorohexyl-2-thieno group. In view of high solubility, one from the group consisting of 4-hexyl-2-thieno group, 4-heptyl-2-thieno group, 4-octyl-2-thieno group, 4-nonyl-2-thieno group, and 4-decyl-2-thieno group is preferred.

In general formula (2), R ⁹ to R ¹³ are preferably hydrogen, halogen, a fluorine-substituted alkyl group having 1 to 20 carbon atoms, or a heteroaryl-2-group having 5 to 26 carbon atoms and a substituent at the 4-position, in order to achieve high mobility, and more preferably one of the group consisting of hydrogen, fluorine, a nonafluorobutyl group, a hendecafluoropentyl group, a tridecafluorohexyl group, a pentadecafluoroheptyl group, a heptadecafluorooctyl group, a 4-hexyl-2-thieno group, a 4-heptyl-2-thieno group, a 4-octyl-2-thieno group, a 4-nonyl-2-thieno group, or a 4-decyl-2-thieno group.

In general formula (2), for R ⁹ to R ¹³ , in order to achieve high mobility and high solubility, it is preferable that R ⁹ is one of the group consisting of a fluorine-substituted alkyl group having 1 to 20 carbon atoms and a heteroaryl-2-group having 5 to 26 carbon atoms and having a substituent at the 4-position, and R ¹⁰ to R ¹³ are one of the group consisting of hydrogen, fluorine, a methyl group, an ethyl group, an n-propyl group and an n-butyl group. For R ¹⁰ to R ¹³ , hydrogen is particularly preferable in order to achieve high mobility.

A more preferred specific skeleton of the biphenylene derivative of the present invention is represented by at least one of the group consisting of the following general formulae (1-1) to (1-22). Among these, from the viewpoint of high solubility, (1-1) to (1-10) are preferred, and from the viewpoint of high mobility, one of the group consisting of general formulae (1-1) to (1-5) having a molecular long axis is preferred, and one of the group consisting of general formulae (1-1) to (1-3) having a point-symmetric structure is even more preferred.

(wherein R ¹ to R ⁸ have the same meanings as R ¹ to R ⁸ in formula (1), and X, Y, and R ⁹ to R ¹³ have the same meanings as X, Y, and R ⁹ to R ¹³ in formula (2).)

(wherein R ¹ to R ⁸ have the same meanings as R ¹ to R ⁸ in formula (1), and X, Y, and R ⁹ to R ¹³ have the same meanings as X, Y, and R ⁹ to R ¹³ in formula (2).)
Specific examples of the biphenylene derivative of the present invention include the following.

As a method for producing the biphenylene derivative of the present invention, any method can be used as long as it is possible to produce the biphenylene derivative.

As a method for producing the biphenylene derivative of the present invention, for example, a biphenylene derivative (1-1a) of general formula (1) in which A in general formula (1) is a covalent bond, R ³ , R ⁴ , R ⁷ , and R ⁸ are hydrogen, and n in general formula (2) is 1, X is sulfur, Y is carbon, R ⁹ is a 4-alkylthieno-2-group, and R ¹³ is hydrogen can be produced by a method including the following steps A1 to G1.

(Step A1): A step of producing 2,2'-dibromo-4,5'-difluorobiphenyl from 1-bromo-4-fluorophenyl-2-zinc chloride derived from 1-bromo-4-fluoro-2-iodobenzene and 2-bromo-4-fluoro-1-iodobenzene in the presence of a palladium catalyst.
(Step B1): A step of producing 2,6-difluorobiphenylene by converting 2,2'-dibromo-4,5'-difluorobiphenyl obtained in Step A1 into a dilithium salt with butyllithium and intramolecularly cyclizing the salt with copper(II) chloride.
(Step C1): A step of producing 2,6-difluoro-1,5-dihalobiphenylene by treating 2,6-difluorobiphenylene obtained in Step B1 with lithium diisopropylamide (hereinafter abbreviated as LDA) and iodinating it.
(Step D1): A step of producing 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene by Sonogashira coupling of the 2,6-difluoro-1,5-dihalobiphenylene obtained in Step C1 with trimethylsilylacetylene in the presence of a palladium/copper catalyst.
(Step E1): A step of reacting 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene obtained in Step D1 with sodium sulfide to produce a biphenylene derivative (unsubstituted).
(Step F1): A step of producing 2,7-dibromodithienobiphenylene by treating the biphenylene derivative (unsubstituted) obtained in Step E1 with butyllithium and then brominating it.
(Step G1): A step of producing a biphenylene derivative (1-1a) by palladium coupling of 2,7-dibromodithienobiphenylene obtained in Step F1 with 2-trimethylstannyl-4-alkylthiophene.

Details of each step from A1 to G1 are given below.

The step A1 is a step of producing 2,2'-dibromo-4,5'-difluorobiphenyl by cross-coupling of 1-bromo-4-fluorophenyl-2-zinc chloride derived from 1-bromo-4-fluoro-2-iodobenzene with 2-bromo-4-fluoro-1-iodobenzene in the presence of a palladium catalyst.
1-Bromo-4-fluorophenyl-2-zinc chloride can be prepared, for example, by exchanging the iodine of 1-bromo-4-fluoro-2-iodobenzene with magnesium halide using an organometallic reagent such as ethyl magnesium chloride or isopropyl magnesium bromide (preparation of 1-bromo-4-fluorophenyl-2-magnesium halide), followed by metal exchange with zinc chloride. Magnesium metal can also be used instead of the organometallic reagent.
The conditions for preparing 1-bromo-4-fluorophenyl-2-magnesium halide include, for example, a temperature range of −80° C. to 20° C. in a solvent such as tetrahydrofuran (hereinafter referred to as THF) or diethyl ether. 1-Bromo-4-fluorophenyl-2-zinc chloride can be prepared by reacting zinc chloride with a solution of the magnesium salt (1-bromo-4-fluorophenyl-2-magnesium halide). Zinc chloride may be in its original state or in a THF or diethyl ether solution. The reaction between the magnesium salt and zinc chloride can be carried out at a temperature range of −80° C. to 30° C.
Examples of the palladium catalyst in Step A1 include tetrakis(triphenylphosphine)palladium, dichlorobis(triphenylphosphine)palladium, etc., and the reaction temperature can be in the range of 20°C to 80°C.

Step B1 is a step of producing 2,6-difluorobiphenylene by converting 2,2'-dibromo-4,5'-difluorobiphenyl obtained in Step A1 into a dilithium salt with 2 or more equivalents of butyllithium and intramolecularly cyclizing the salt with copper(II) chloride.
The dilithium salt can be prepared, for example, by using 2 to 3 equivalents of n-butyllithium or tert-butyllithium in a solvent such as THF or diethyl ether at a temperature range of -80°C to 20°C.
Copper(II) chloride is used in an amount of 1 to 3 equivalents relative to the dilithium salt, and the intramolecular cyclization reaction can be carried out at a temperature range of −80° C. to 30° C. Copper(II) bromide can also be used in place of copper(II) chloride.

Step C1 is a step in which 2,6-difluorobiphenylene obtained in Step B1 is reacted with LDA to generate dilithium salts at the 1- and 5-positions, and then halogenated to produce 2,6-difluoro-1,5-dihalobiphenylene.
The reaction with LDA can be carried out, for example, using 2 to 4 equivalents of LDA in a solvent such as THF or diethyl ether at a temperature range of −80° C. to 20° C. The reaction of the dilithium salt with a halogenating agent can be carried out at a temperature range of −80° C. to 30° C.
Instead of LDA, n-butyllithium or n-butyllithium/tetramethylethylenediamine can be used, and as the halogenating agent, iodine, 1-chloro-2-iodoethane, N-iodosuccinimide, bromotrichloromethane, tetrabromomethane, 1,2-dibromotetrachloroethane, N-bromosuccinimide (hereinafter abbreviated as NBS), N-fluorobenzenesulfonimide, or the like can be used.

Step D1 is a step of producing 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene by Sonogashira coupling of 2,6-difluoro-1,5-dihalobiphenylene obtained in Step C1 with trimethylsilylacetylene in the presence of a palladium catalyst and a copper catalyst.
Examples of the palladium catalyst include tetrakis(triphenylphosphine)palladium and dichlorobis(triphenylphosphine)palladium, and examples of the copper catalyst include copper(I) iodide, copper(I) bromide, and copper(I) chloride. The Sonogashira coupling can be carried out in a solvent such as triethylamine, diisopropylamine, diisopropylethylamine, piperidine, or pyridine at a temperature range of 20° C. to 80° C. Toluene, THF, or the like may be added as a solvent.
As the alkynyl compound in Step D1, an alkynyl compound having R ⁹ can also be used to synthesize (1-1a). For example, by using heptadecafluoro-1-decyne or the like, the synthesis of (1-1a) can be completed in the subsequent Step E1.

Step E1 is a step of producing an unsubstituted 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene obtained in Step D1 by reacting it with sodium sulfide.
The reaction can be carried out in a solvent such as dimethylsulfoxide (hereinafter abbreviated as DMSO), N,N-dimethylformamide (hereinafter abbreviated as DMF), or N-methylpyrrolidone (hereinafter abbreviated as NMP) at a temperature range of 40 to 200° C.
This step can also be carried out using known reaction conditions for synthesizing a benzothiophene ring from a 2-haloalkynylbenzene (for example, Organic Letters, 2009, Vol. 11, pp. 2473-2475).

Step F1 is a step of producing a dibromo biphenylene derivative from the biphenylene derivative (unsubstituted) obtained in Step E1 by treating with butyllithium/bromination.
This reaction can be carried out by abstracting the 2-position proton of the terminal thiophene ring with butyllithium, followed by the addition of, for example, dibromotetrachloroethane to effect dibromination.

The step G1 is a step of producing a biphenylene derivative (1-1a) by palladium coupling of 2,7-dibromodithienobiphenylene obtained in the step F1 with 2-trimethylstannyl-4-alkylthiophene.
The reaction can be carried out by heating and stirring, for example, 2-trimethylstannyl-4-octylthiophene in the presence of lithium chloride and a palladium catalyst to produce a biphenylene derivative (1-1a).

The specific manufacturing method, which is preferred because it requires fewer reaction steps, is shown in the reaction scheme below.

On the other hand, among the biphenylene derivatives of general formula (1) used in the present invention, a biphenylene derivative (1-2a) of general formula (1) in which A is a covalent bond, R ³ , R ⁴ , R ⁷ and R ⁸ are hydrogen, n in general formula (2) is 1, X is sulfur, Y is carbon, R ¹³ is hydrogen and R ⁹ is a 4-alkylthienyl-2- group can be produced by a method including the following steps A2 to F2.

(Step A2): A step of producing 2,2'-dibromo-3,6'-difluorobiphenyl from 1-bromo-3-fluorophenyl-2-zinc chloride derived from 1-bromo-3-fluoro-2-iodobenzene and 2-bromo-1-fluoro-3-iodobenzene in the presence of a palladium catalyst.
(Step B2): A step of dilithiating the 2,2'-dibromo-3,6'-difluorobiphenyl obtained in Step A2 with butyllithium, followed by reacting with N-fluorobenzenesulfonimide to produce 1,5-difluorobiphenylene.
(Step C2): A step of reacting the 1,5-difluorobiphenylene obtained in Step B2 with sodium sulfide to form a dithiol, which is then reacted with 2-bromoacetaldehyde dimethyl acetal to produce biphenylene-1,5-bis(thioacetaldehyde dimethyl acetal).
(Step D2): A step of cyclizing the biphenylene-1,5-bis(thioacetaldehyde dimethyl acetal) obtained in Step C2 with a phosphoric acid catalyst to produce an unsubstituted dithienobiphenylene.
(Step E2): A step of producing 2,7-dibromodithienobiphenylene from the biphenylene derivative (unsubstituted) obtained in Step D2 by treating with butyllithium/bromination.
(Step F2): A step of producing a biphenylene derivative (1-2a) by palladium coupling of 2,7-dibromodithienobiphenylene obtained in Step E2 with 2-trimethylstannyl-4-alkylthiophene.

Details of each step from A2 to F2 are given below.

In steps A2 to F2, the biphenylene derivative represented by (1-2a) can be produced using the reagents and reaction conditions in steps A1 to G1 above, except that 1-bromo-3-fluoro-2-iodobenzene and 2-bromo-1-fluoro-3-iodobenzene are used in step A2.

Details of each process are shown below.

Step B2 is a step of producing 1,5-difluorobiphenylene by, for example, dilithiating 2,2'-dibromo-3,6'-difluorobiphenyl obtained in Step A2 with 2 equivalents or more of butyllithium, generating benzyne, which is then intramolecularly cyclized, and fluorinating the benzyne with N-fluorobenzenesulfonimide.
The dilithiation can be carried out, for example, using 2 to 3 equivalents of n-butyllithium or tert-butyllithium in a solvent such as THF or diethyl ether at a temperature range of −80° C. to 20° C. Fluorination with N-fluorobenzenesulfonimide can be carried out in a solvent such as THF or diethyl ether at a temperature range of −80° C. to 20° C.

In step C2, for example, 1,5-difluorobiphenylene is reacted with 2 to 6 equivalents of sodium sulfide (hydrate) in a solvent such as DMF or NMP at 90°C to 150°C to produce the disodium salt of biphenylene-1,5-dithiol, and then 2-bromoacetaldehyde dimethyl acetal is added and treated at 90°C to 150°C.

In step D2, for example, biphenylene-1,5-bis(thioacetaldehyde dimethyl acetal) obtained in step C2 is reacted in a solvent such as xylene or chlorobenzene at 110 to 140°C in the presence of a catalyst such as 5 to 500 wt % phosphoric acid or polyphosphoric acid. This allows the production of an unsubstituted biphenylene derivative.

Steps F2 and G2 are the same reactions as steps F1 and G1, respectively.

The specific manufacturing method, which is preferred because it requires fewer reaction steps, is shown in the reaction scheme below.

Furthermore, among the biphenylene derivatives of general formula (1) used in the present invention, a biphenylene derivative (1-3a) of general formula (1-3) in which A is a covalent bond, R ¹ , R ⁴ , R ⁵ and R ⁸ are hydrogen, and n in general formula (2) is 1, X is sulfur, Y is carbon, R ⁹ is a 4-alkylthienyl-2- group and R ¹³ is hydrogen can be produced by a method that uses 2,6-difluorobiphenylene obtained in the above steps A1 and B1 as a raw material and goes through the following steps C3 to G3.

(Step C3): A step of halogenating the 2,6-difluorobiphenylene obtained in Step B1 to produce 3,7-difluoro-2,6-dihalobiphenylene.
(Step D3): A step of producing 3,7-difluoro-2,6-bis(trimethylsilylethynyl)biphenylene by Sonogashira coupling of the 3,7-difluoro-2,6-dihalobiphenylene obtained in Step C3 with trimethylsilylacetylene in the presence of a palladium/copper catalyst.
(Step E3): A step of reacting the 3,7-difluoro-2,6-bis(trimethylsilylethynyl)biphenylene obtained in Step D3 with sodium sulfide to produce an unsubstituted product.
(Step F3): A step of producing 2,7-dibromodithienobiphenylene by treating the biphenylene derivative (unsubstituted) obtained in Step E3 with butyllithium and brominating it.
(Step G3): A step of producing a biphenylene derivative (1-3a) by palladium coupling of 2,7-dibromodithienobiphenylene obtained in Step F3 with 2-trimethylstannyl-4-alkylthiophene.

Step C3 in the reaction process is, for example, a step of reacting 2,6-difluorobiphenylene obtained in step B1 with a halogenating agent to halogenate the 3- and 7-positions to produce 3,7-difluoro-2,6-dihalobiphenylene.
The reaction with a halogenating agent can be carried out, for example, using 2 to 4 equivalents of the halogenating agent in a solvent such as DMF, NMP, or DMSO at a temperature within the range of 20°C to 70°C.
As the halogenating agent, NBS, bromine, iodine, N-iodosuccinimide, or the like can be used.

In steps D3 to G3, the biphenylene derivative represented by (1-3a) can be produced using the reagents and reaction conditions of steps D1 to G1 described above, except that 3,7-difluoro-2,6-dihalobiphenylene is used in step D3.

The specific manufacturing method, which is preferred because it requires fewer reaction steps, is shown in the reaction scheme below.

The biphenylene derivative of the present invention can be dissolved in a suitable solvent to form a solution for forming an organic semiconductor layer containing the biphenylene derivative. Any solvent can be used as the solvent as long as it is capable of dissolving the biphenylene derivative represented by the general formula (1). Since the drying speed of the solvent can be made suitable when forming the organic semiconductor layer, an organic solvent having a boiling point of 100°C or higher at normal pressure is preferred.

Solvents that can be used in the present invention are not particularly limited, and examples thereof include aromatic hydrocarbons such as toluene, mesitylene, o-xylene, isopropylbenzene, pentylbenzene, cyclohexylbenzene, 1,2,4-trimethylbenzene, tetralin, and indane; aromatic ethers such as anisole, 2-methylanisole, 3-methylanisole, 2,3-dimethylanisole, 3,4-dimethylanisole, 2,6-dimethylanisole, ethylphenyl ether, butylphenyl ether, 1,2-methylenedioxybenzene, and 1,2-ethylenedioxybenzene; aromatic halogen compounds such as chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, and 1,4-difluorobenzene; thiophene, 3-chlorothiophene, 2-chlorothiophene, and the like. Heteroaromatics such as thiophene, 3-methylthiophene, 2-methylthiophene, benzothiophene, 2-methylbenzothiophene, 2,3-dihydrobenzothiophene, furan, 3-methylfuran, 2-methylfuran, 2,5-dimethylfuran, benzofuran, 2-methylbenzofuran, 2,3-dihydrobenzofuran, thiazole, oxazole, benzothiazole, benzoxazole, and pyridine; saturated hydrocarbons such as hexane, cyclohexane, heptane, octane, nonane, decane, undecane, dodecane, and decalin; dipropylene glycol dimethyl ether, dipropylene glycol diacetate, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, 1,3-butylene glycol diacetate Examples of the ester include glycols such as dimethyl phthalate, diethyl phthalate, dimethyl terephthalate, phenyl acetate, cyclohexanol acetate, 3-methoxybutyl acetate, tetrahydrofurfuryl acetate, tetrahydrofurfuryl propionate, and γ-butyrolactone; and cyclic ethers such as THF and 2-methoxymethyltetrahydrofuran. Among these, preferred are toluene, o-xylene, mesitylene, 1,2,4-trimethylphenyl ether, and 1,2,4-trimethylphenyl ether. These have an appropriate drying speed, and therefore are preferred. At least one of the group consisting of methylbenzene, tetralin, indane, octane, nonane, decane, anisole, 2-methylanisole, 3-methylanisole, 2,3-dimethylanisole, 3,4-dimethylanisole, 2,6-dimethylanisole, ethylphenyl ether, butylphenyl ether, 1,2-methylenedioxybenzene, 1,2-ethylenedioxybenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 3-methylthiophene, and benzothiazole is preferred, and at least one of the group consisting of toluene, o-xylene, mesitylene, tetralin, indane, octane, nonane, decane, anisole, 2-methylanisole, 3-methylanisole, 2,3-dimethylanisole, 3,4-dimethylanisole, and 2,6-dimethylanisole is more preferred.

In addition, the solvent used in the present invention can be one type of solvent used alone, or two or more types of solvents with different properties such as boiling point, polarity, solubility parameters, etc. can be mixed and used.

The temperature at which the biphenylene derivative represented by the general formula (1) is mixed and dissolved in a solvent is preferably in the range of 0 to 80° C., more preferably 10 to 60° C., in order to promote dissolution.
The time for dissolving and mixing the biphenylene derivative represented by the general formula (1) in the organic solvent is preferably 1 minute to 1 hour in order to obtain a homogeneous solution.
In the present invention, when the concentration of the biphenylene derivative represented by the general formula (1) in the organic semiconductor layer forming solution of the present invention is in the range of 0.1 to 10.0% by weight, the solution becomes easy to handle and the efficiency in forming the organic semiconductor layer becomes superior. Also, when the viscosity of the organic semiconductor layer forming solution is in the range of 0.3 to 10 mPa·s, more suitable coatability is exhibited.

Since the biphenylene derivative itself has a moderate degree of coagulation, the solution can be prepared at a relatively low temperature, and since it is resistant to oxidation, it can be suitably applied to the production of organic thin films by coating. In other words, since there is no need to remove air from the atmosphere, the coating process can be simplified. Furthermore, the solution can be used to produce organic thin films, such as polystyrene, poly(α-methylstyrene), poly(4-methylstyrene), poly(1-vinylnaphthalene), poly(2-vinylnaphthalene), poly(styrene-block-butadiene-block-styrene), poly(styrene-block-isoprene-block-styrene), poly(vinyltoluene), poly(styrene-co-2,4-dimethylstyrene), poly(chlorostyrene), poly(styrene-co-α-methylstyrene), poly(styrene-co-butadiene), poly(ethylene-co-norbornene), polyphenylene ether, polycarbonate, polycarbazole, polytriarylamine, poly(9,9-dioctyl styrene), poly(1-vinylnaphthalene ... At least one of the group consisting of poly(N-vinylcarbazole), polymethyl methacrylate, poly(styrene-co-methyl methacrylate), polyethyl methacrylate, poly(n-propyl methacrylate), polyisopropyl methacrylate, poly(n-butyl methacrylate), polyphenyl methacrylate, polymethyl acrylate, polyethyl acrylate, and poly(n-propyl acrylate) can be mentioned, and preferably at least one polymer from the group consisting of polystyrene, poly(α-methylstyrene), poly(ethylene-co-norbornene), and polymethyl methacrylate can also be present as a binder. The concentration of these polymer binders is preferably 0.001 to 10.0% by weight in order to obtain a suitable solution viscosity.

The glass transition temperature (Tg) of the polymer binder is preferably 105°C or higher, more preferably 120°C or higher, and particularly preferably 150°C or higher, since this is more suitable for handling process temperatures during the manufacture of electronic devices.

The molecular weight of the polymer is preferably 5,000 to 1,000,000, more preferably 10,000 to 500,000, and particularly preferably 20,000 to 100,000, since this is suitable for obtaining an organic thin-film transistor with a higher carrier mobility. In the present invention, the molecular weight of the polymer refers to the weight average molecular weight (Mw) in terms of polystyrene.

The polymer acts as a general polymer binder and improves the film-forming properties of the resulting organic semiconductor layer, and insulating polymers and semiconducting polymers can also be used.

The semiconducting polymer may be, for example, at least one of polytriarylamine and poly(9,9-dioctylfluorene-co-dimethyltriarylamine).

Specific examples of polymers that can be used as the polymer binder in the present invention include, in addition to the polymers listed above, at least one member selected from the group consisting of polar cyclic polyolefins, polysulfones, acrylonitrile-styrene copolymers, and methyl methacrylate-styrene copolymers.

More specifically, the polar cyclic polyolefins are preferably polymers represented by the following general formula (4):

(wherein R ¹⁴ to R ¹⁶ each independently represent one of the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkyloxycarbonyl group having 2 to 20 carbon atoms, an aryloxycarbonyl group having 7 to 20 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a hydroxyl group, an amino group, or an alkylamino group having 1 to 20 carbon atoms; and X ² represents one member of the group consisting of a halogen atom, an alkyloxycarbonyl group having 2 to 20 carbon atoms, an aryloxycarbonyl group having 7 to 20 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a hydroxyl group, an amino group, or an alkylamino group having 1 to 20 carbon atoms. p represents an integer of 20 to 5,000, and q and r each independently represent an integer of 0 to 2. A bond consisting of a solid line and a dotted line represents a single bond or a double bond.
R ¹⁴ to R ¹⁶ in general formula (4) each independently represent one of the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkyloxycarbonyl group having 2 to 20 carbon atoms, an aryloxycarbonyl group having 7 to 20 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a hydroxyl group, an amino group, or an alkylamino group having 1 to 20 carbon atoms, and a hydrogen atom or an alkyl group having 1 to 20 carbon atoms is preferred for high heat resistance.

Examples of the alkyl group having 1 to 20 carbon atoms in R ¹⁴ to R ¹⁶ include a straight-chain or branched alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and an n-pentyl group. Examples of the aryl group having 6 to 20 carbon atoms include a phenyl group, a p-tolyl group, a p-(n-hexyl)phenyl group, a p-(n-octyl)phenyl group, and a p-(2-ethylhexyl)phenyl group. Examples of the alkyloxycarbonyl group having 2 to 20 carbon atoms include a methyloxycarbonyl group, an ethyloxycarbonyl group, and an n-propyloxycarbonyl group. Examples of the aryloxycarbonyl group having 7 to 20 carbon atoms include a phenoxycarbonyl group and a 4-methylphenoxycarbonyl group. Examples of the alkoxy group having 1 to 20 carbon atoms include one selected from the group consisting of a methoxy group, an ethoxy group, and an n-propoxy group. Examples of the aryloxy group having 6 to 20 carbon atoms include at least one selected from the group consisting of a phenoxy group and a 4-methylphenoxy group. Examples of the alkylamino group having 1 to 20 carbon atoms include at least one selected from the group consisting of a methylamino group, an ethylamino group, and an n-propylamino group. Among these, in view of high heat resistance, it is preferable that the substituent R ¹⁴ is one selected from the group consisting of a methyl group, an ethyl group, and an n-propyl group, and it is preferable that the substituents R ¹⁵ and R ¹⁶ are hydrogen atoms.

^X2 in the general formula (4) represents one member selected from the group consisting of a halogen atom, an alkyloxycarbonyl group having 2 to 20 carbon atoms, an aryloxycarbonyl group having 7 to 20 carbon atoms, a cyano group, a nitro group, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a hydroxyl group, an amino group, or an alkylamino group having 1 to 20 carbon atoms.

Examples of the alkyloxycarbonyl group having 2 to 20 carbon atoms in the substituent ^X2 include one selected from the group consisting of a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an n-butoxycarbonyl group, an n-hexyloxycarbonyl group, and a cyclohexyloxycarbonyl group, and examples of the aryloxycarbonyl group having 7 to 20 carbon atoms include one selected from the group consisting of a phenoxycarbonyl group, a 4-methylphenoxycarbonyl group, a 2,4-dimethylphenoxycarbonyl group, and a 4-ethylphenoxycarbonyl group. Examples of the alkoxy group having 1 to 20 carbon atoms include a methoxy group or an ethoxy group. Examples of the aryloxy group having 6 to 20 carbon atoms include a phenoxy group or a 4-methylphenoxy group. Examples of the alkylamino group having 1 to 20 carbon atoms include a methylamino group, an ethylamino group, and an n-propylamino group. For high solubility and high heat resistance, an alkyloxycarbonyl group having 2 to 20 carbon atoms is preferred.
p represents an integer of 20 to 5,000, and is preferably 40 to 2,000 since this is suitable for obtaining an organic thin film transistor with higher carrier mobility. q represents an integer of 0 to 2, and is preferably 1. r represents an integer of 0 to 2, and is preferably 0 or 1, and is more preferably 0.
A bond consisting of a solid line and a dotted line represents a single bond or a double bond, and is preferably a single bond for thermal stability.

There are no particular limitations on the polysulfones used as polymer binders in the present invention as long as they have a polysulfone structure, and more specific examples include the polysulfones shown in Polysulfones 1 to 5 below.

(wherein, the substituents R ¹⁷ to R ²⁰ each independently represent an alkyl group having 1 to 20 carbon atoms, and s represents an integer of 10 to 20,000.)
Examples of the alkyl group having 1 to 20 carbon atoms in the substituents R ¹⁷ to R ²⁰ include at least one member selected from the group consisting of straight-chain or branched alkyl groups such as a methyl group, an ethyl group, a n-propyl group, a n-butyl group, an isobutyl group, a n-pentyl group, a n-hexyl group, an isohexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, a n-decyl group, a n-dodecyl group, a n-tetradecyl group, a n-octadecyl group, a 2-ethylhexyl group, a 3-ethylheptyl group, a 3-ethyldecyl group, and a 2-hexyldecyl group.
s represents an integer of 10 to 20,000, and preferably an integer of 10 to 10,000.

The acrylonitrile-styrene copolymer used as the polymer binder in the present invention is a copolymer of acrylonitrile and styrene in any ratio, and since it exhibits good electrical properties and improves reliability by reducing the change in threshold voltage when bias stress is applied, the weight ratio of acrylonitrile to styrene is preferably 10:90 to 50:50, and more preferably 20:80 to 40:60.

The methyl methacrylate-styrene copolymer used as the polymer binder in the present invention is a copolymer of methyl methacrylate and styrene in any ratio, and exhibits good electrical properties and improves reliability by reducing the change in threshold voltage when bias stress is applied. Therefore, the molar ratio of methyl methacrylate to styrene is preferably 1:99 to 90:10, and more preferably 1:99 to 70:30.

The polymer used as the polymer binder in the present invention may have its surface energy adjusted by a surface treatment agent. A silane coupling agent may be used as the surface treatment agent, and specific examples thereof include at least one of the group consisting of 1,1,1,3,3,3-hexamethyldisilazane, phenyltrimethoxysilane, octyltrichlorosilane, β-phenethyltrichlorosilane, and β-phenethyltrimethoxysilane. The polymer used in the present invention may be one type of polymer used alone, or a mixture of two or more types of polymers. Furthermore, it is also possible to use a mixture of polymers with different molecular weights.

The coating method for forming an organic semiconductor layer using the organic semiconductor layer-forming solution of the present invention is not particularly limited as long as it is a method capable of forming an organic semiconductor layer, and examples thereof include simple coating methods such as spin coating, drop casting, dip coating, and cast coating; and at least one printing method selected from the group consisting of dispenser, inkjet, slit coating, blade coating, flexographic printing, screen printing, gravure printing, and offset printing. Among these, at least one method selected from the group consisting of spin coating, drop casting, and inkjet is preferred because it allows for an organic semiconductor layer to be formed easily and efficiently.

After applying the organic semiconductor layer forming solution of the present invention, the solvent is dried and removed, thereby forming an organic semiconductor layer using the organic semiconductor layer forming solution.

When drying and removing the solvent from the applied organic semiconductor layer, there are no particular limitations on the drying conditions, and the solvent can be dried and removed, for example, under normal pressure or reduced pressure.

There is no particular limit to the temperature at which the organic solvent is dried and removed from the applied organic semiconductor layer, but it is preferable to perform the drying and removal at a temperature in the range of 10 to 150°C, since this allows the organic solvent to be efficiently dried and removed from the applied organic semiconductor layer and makes it possible to form an organic semiconductor layer.

When the organic solvent is dried and removed from the applied organic semiconductor layer, it is possible to control the crystal growth of the biphenylene derivative represented by general formula (1) by adjusting the evaporation rate of the organic solvent being removed.

There is no limit to the thickness of the organic semiconductor layer formed by the organic semiconductor layer-forming solution of the present invention, and since good carrier mobility can be obtained, the thickness is preferably in the range of 1 nm to 1 μm, and more preferably in the range of 10 nm to 300 nm.

After forming the organic semiconductor layer, the resulting organic semiconductor layer may be annealed at 40 to 180°C.

The organic semiconductor layer formed from the organic semiconductor layer-forming solution of the present invention can be used as an organic semiconductor device comprising the organic semiconductor layer, in particular an organic thin-film transistor comprising the organic semiconductor layer.

An organic thin-film transistor can be obtained by laminating an organic semiconductor layer provided with a source electrode and a drain electrode and a gate electrode on a substrate via an insulating layer. By using an organic semiconductor layer formed from the organic semiconductor layer-forming solution of the present invention as the organic semiconductor layer, it is possible to obtain an organic thin-film transistor that exhibits excellent semiconductor and electrical properties.

Figure 1 shows the cross-sectional structure of a typical organic thin-film transistor. Here, (A) is a bottom gate-top contact type, (B) is a bottom gate-bottom contact type, (C) is a top gate-top contact type, and (D) is a top gate-bottom contact type organic thin-film transistor, where 1 is an organic semiconductor layer, 2 is a substrate, 3 is a gate electrode, 4 is a gate insulating layer, 5 is a source electrode, and 6 is a drain electrode. The organic semiconductor layer formed from the organic semiconductor layer forming solution of the present invention can be applied to any of the organic thin-film transistors.

The substrate according to the present invention is not particularly limited, and may be at least one of the following: plastic substrates such as polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polymethyl acrylate, polyethylene, polypropylene, polystyrene, cyclic polyolefin, fluorinated cyclic polyolefin, polyimide, polycarbonate, polyvinylphenol, polyvinyl alcohol, poly(diisopropyl fumarate), poly(diethyl fumarate), poly(diisopropyl maleate), polyethersulfone, polyphenylene sulfide, and cellulose triacetate; inorganic substrates such as glass, quartz, aluminum oxide, silicon, highly doped silicon, silicon oxide, tantalum dioxide, tantalum pentoxide, and indium tin oxide; and metal substrates such as gold, copper, chromium, titanium, and aluminum. When highly doped silicon is used as the substrate, the substrate can also serve as the gate electrode.

The gate electrode according to the present invention is not particularly limited, and may be at least one of the following: inorganic materials such as aluminum, gold, silver, copper, highly doped silicon, tin oxide, indium oxide, indium tin oxide, chromium, titanium, tantalum, graphene, and carbon nanotubes; and organic materials such as doped conductive polymers (e.g., PEDOT-PSS).

The above inorganic materials can also be used as metal nanoparticle inks without any problems. In this case, the solvent is preferably at least one of the following groups: polar solvents such as water, methanol, ethanol, 2-propanol, 1-butanol, and 2-butanol, which provide adequate dispersibility; aliphatic hydrocarbon solvents having 6 to 14 carbon atoms such as hexane, heptane, octane, decane, dodecane, and tetradecane; and aromatic hydrocarbon solvents having 7 to 14 carbon atoms such as toluene, xylene, mesitylene, ethylbenzene, pentylbenzene, hexylbenzene, octylbenzene, cyclohexylbenzene, tetralin, indane, anisole, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, 1,2-dimethylanisole, 2,3-dimethylanisole, and 3,4-dimethylanisole. After coating the nanoparticle ink, it is preferable to perform an annealing treatment at a temperature range of 80°C to 200°C to improve conductivity.

The gate insulating layer according to the present invention is not particularly limited, and examples thereof include inorganic materials such as silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, titanium oxide, tantalum dioxide, tantalum pentoxide, indium tin oxide, tin oxide, vanadium oxide, barium titanate, and bismuth titanate; polymethyl methacrylate, polymethyl acrylate, polyimide, polyamic acid polycarbonate, polyvinylphenol, polyvinyl alcohol, poly(diisopropyl fumarate), poly(diethyl fumarate), polyethylene terephthalate, polyethylene naphthalate, polyethyl cinnamate, polymethyl cinnamate, and polyethyl crotonate. , polyethersulfone, polypropylene-co-1-butene, polyisobutylene, polypropylene, polycyclopentane, polycyclohexane, polycyclohexane-ethylene copolymer, polyfluorinated cyclopentane, polyfluorinated cyclohexane, polyfluorinated cyclohexane-ethylene copolymer, BCB resin (product name: Cyclotene, manufactured by Dow Chemical Company), Cytop (trademark), Teflon (trademark), Parylene (trademark) such as Parylene C, and preferably a polymer insulating material (polymer gate insulating layer) to which a coating method can be applied, since the manufacturing method is simple.

There are no particular limitations on the solvent used to dissolve the polymer material, and examples of the solvent include aliphatic hydrocarbon solvents having 6 to 14 carbon atoms, such as hexane, heptane, octane, decane, dodecane, and tetradecane; ether-based solvents, such as THF, 1,2-dimethoxyethane, and dioxane; alcohol-based solvents, such as ethanol, isopropyl alcohol, 1-butanol, 2-butanol, 2-ethylhexanol, and tetrahydrofurfuryl alcohol; ketone-based solvents, such as acetone, methyl ethyl ketone, diethyl ketone, diisopropyl ketone, and acetophenone; ester-based solvents, such as ethyl acetate, γ-butyrolactone, cyclohexanol acetate, 3-methoxybutyl acetate, tetrahydrofurfuryl acetate, and tetrahydrofurfuryl propionate; amide-based solvents, such as DMF and NMP; dipropylene glycol. Examples of the solvent include glycol-based solvents such as ethyl dimethyl ether, dipropylene glycol diacetate, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, 1,6-hexanediol diacetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate; and fluorinated solvents such as perfluorohexane, perfluorooctane, 2-(pentafluoroethyl)hexane, and 3-(pentafluoroethyl)heptane.

The concentration of the polymer insulating material is, for example, 0.1 to 10.0% by weight at a temperature of 20 to 40°C. There is no limit to the film thickness of the insulating layer obtained at this concentration, and from the viewpoint of insulation resistance, it is preferably 100 nm to 1 μm, and more preferably 150 nm to 900 nm.

The surface of these gate insulating layers can be modified with at least one of the following: silanes such as octadecyltrichlorosilane, decyltrichlorosilane, decyltrimethoxysilane, octyltrichlorosilane, octadecyltrimethoxysilane, β-phenethyltrichlorosilane, β-phenethyltrimethoxysilane, phenyltrichlorosilane, and phenyltrimethoxysilane; phosphonic acids such as octadecylphosphonic acid, decylphosphonic acid, and octylphosphonic acid; and silylamines such as hexamethyldisilazane. Generally, by performing surface treatment on the gate insulating layer, the crystal grain size of the organic semiconductor material is increased and the molecular orientation is improved, resulting in favorable results such as improved carrier mobility, improved current on/off ratio, and lowered threshold voltage.

There are no particular limitations on the materials for the source and drain electrodes of the organic thin-film transistor of the present invention, and the same materials as those for the gate electrode can be used. The materials may be the same as or different from those for the gate electrode, and different materials may be laminated. In addition, in order to increase the carrier injection efficiency, surface treatment can be performed on these electrode materials. Examples of surface treatment agents used for surface treatment include at least one selected from the group consisting of benzenethiol, pentafluorobenzenethiol, 4-fluorobenzenethiol, 4-methoxybenzenethiol, etc.

The organic thin film transistor of the present invention preferably has a carrier mobility of 0.20 cm ² /V·sec or more for fast operation, and a current on/off ratio of 1.0×10 ⁶ or more for high switching characteristics.

The organic thin-film transistor of the present invention can be used in electronic materials such as organic semiconductor layer applications of transistors for electronic paper, organic EL displays, liquid crystal displays, IC tags (RFID tags), pressure sensors, and biosensors; organic EL display materials; organic semiconductor laser materials; organic thin-film solar cell materials; and photonic crystal materials. Since the biphenylene derivative represented by the general formula (1) forms a crystalline thin film, it is preferable to use it as a semiconductor layer application of an organic thin-film transistor.

The novel biphenylene derivative of the present invention provides high carrier mobility and has high heat resistance and suitable solubility. Therefore, it is possible to provide an organic thin-film transistor that exhibits excellent semiconductor properties by coating, and the effect is extremely high.

FIG. 3 is a diagram showing the cross-sectional structure of an organic thin-film transistor.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

The product was identified by ¹ H NMR spectrum, gas chromatography-mass spectrum (GCMS), and liquid chromatography-mass spectrum (LCMS) analyses.
< ^1H NMR Spectral Analysis>
Apparatus: Delta V5 (400 MHz), manufactured by JEOL Ltd.
Measurement temperature: 23°C (if no temperature is specified)
<Gas chromatography-mass spectrometry analysis>
Apparatus: PerkinElmer, (trade name) Auto System XL (MS part: Turbo Mass Gold) (Synthesis Examples 1, 2, 4, and 6)
Apparatus: Shimadzu Corporation, (product name) QP-2010 Ultra (Synthesis Examples 9 and 11)
Column: J&W Scientific, (product name) DB-1, 30 m.
MS ionization: electron impact (EI) method (70 electron volts)

The progress of the reaction was confirmed by thin layer chromatography, gas chromatography (GC) and liquid chromatography (LC). The purity of the biphenylene derivative was also measured by liquid chromatography.
<Thin Layer Chromatography Analysis>
Merck's PLC silica gel 60F254 0.5 mm for thin layer chromatography was used, and hexane and/or toluene were used as the developing solvent.
<Gas Chromatography Analysis>
Apparatus: Shimadzu Corporation, (product name) GC2014
Column: Agilent (trade name) DB-1, 30 m
<Liquid Chromatography Analysis>
Equipment: Tosoh (controller: PX-8020, pump: CCPM-II, degasser: SD-8022)
Column: Tosoh Corporation, (product name) ODS-100V, 5 μm, 4.6 mm×250 mm
Column temperature: 33°C
Eluent: dichloromethane:acetonitrile = 2:8 (volume ratio)
Flow rate: 1.0 ml/min. Detector: UV (manufactured by Tosoh Corporation, (trade name) UV-8020, wavelength: 254 nm).

The melting points of the biphenylene derivatives were measured using a DSC (differential scanning calorimeter).
<DSC Measurement>
Apparatus: SII NanoTechnology, model: DSC6220
Temperature increase/decrease rate: 10° C./min
Scanning range: -10°C to 300°C

Synthesis Example 1 (Synthesis of 2,2'-dibromo-4,5'-difluorobiphenyl) (Step A1)
Under a nitrogen atmosphere, 3.95 g (13.1 mmol) of 1-bromo-4-fluoro-2-iodobenzene (Tokyo Chemical Industry Co., Ltd.) and 15 ml of THF (dehydrated grade) were added to a 100 ml Schlenk reaction vessel. The solution was cooled to 0°C, and 6.8 ml (13.6 mmol) of a THF solution of ethyl magnesium chloride (Sigma-Aldrich, 2.0 M) was added dropwise. The mixture was aged at 0°C for 15 minutes to prepare 1-bromo-4-fluorophenyl-2-magnesium chloride.
Meanwhile, under a nitrogen atmosphere, 2.42 g (17.7 mmol) of zinc chloride (Wako Pure Chemical Industries) and 19 ml of THF (dehydrated grade) were added to another 100 ml Schlenk reaction vessel, and the vessel was cooled to 0° C. The previously prepared 1-bromo-4-fluorophenyl-2-magnesium chloride solution was added dropwise to the resulting white fine slurry solution using a Teflon (registered trademark) cannula, and the 100 ml Schlenk reaction vessel and the Teflon (registered trademark) cannula were further washed with 2 ml of THF (dehydrated grade) and charged into the vessel. The resulting mixture was stirred while gradually increasing the temperature to room temperature. To the resulting slurry of 1-bromo-4-fluorophenyl-2-zinc chloride, 3.18 g (10.5 mmol) of 2-bromo-4-fluoro-1-iodobenzene (Tokyo Chemical Industry Co., Ltd.) and 115 mg (0.0995 mmol, 0.948 mol% relative to 2-bromo-4-fluoro-1-iodobenzene) of tetrakis(triphenylphosphine)palladium (Tokyo Chemical Industry Co., Ltd.) were added as a catalyst. After the reaction was carried out at 50°C for 7 hours, the reaction was stopped by cooling the vessel with water and adding 1M hydrochloric acid. Toluene and saline were added, and the organic phase was separated. The organic phase was washed with saline and dried over anhydrous sodium sulfate. The mixture was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent: hexane). 3.48 g of colorless oil of 2,2'-dibromo-4,5'-difluorobiphenyl was obtained (yield 94%).
MS m/z: 350 (M ⁺⁺ 2, 51%), 348 (M ⁺ , 100%), 346 (M ⁺ -2, 53).
^1H NMR ( _CDCl3 ): δ = 7.62 (dd, J = 8.7 Hz, 5.4 Hz, 1H), 7.43 (dd, J = 8.2 Hz, 2.3 Hz, 1H), 7.27-7.19 (m, 1H), 7.11 (dt, J = 8.2 Hz, 2.7 Hz, 1H), 7.04-6.96 (m, 2H).

Synthesis Example 2 (Synthesis of 2,6-difluorobiphenylene) (Step B1)
In a nitrogen atmosphere, 3.30 g (9.48 mmol) of 2,2'-dibromo-4,5'-difluorobiphenyl synthesized in Synthesis Example 1 and 160 ml of THF (dehydrated grade) were added to a 100 ml Schlenk reaction vessel. The mixture was cooled to -78°C, and 12.5 ml (20.0 mmol) of a hexane solution of n-butyllithium (Kanto Chemical, 1.6 M) was added dropwise. The mixture was aged at -78°C for 1 hour. 3.75 g (27.9 mmol) of copper(II) chloride (Wako Pure Chemical Industries, Ltd.) was added to the mixture at -78°C. The mixture was stirred while gradually increasing the temperature to room temperature. 1 M hydrochloric acid was added to the reaction mixture, and then toluene was added to separate the phases. The organic phase was washed twice with saline and dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent: hexane). As a result, 1.48 g of a pale yellow solid of 2,6-difluorobiphenylene was obtained (yield 91%).
MS m/z: 188 (M ⁺ , 100%).
^1H NMR ( _CDCl3 ): δ = 6.56 (dd, J = 11 Hz, 4.0 Hz, 2H), 6.42-6.35 (m, 4H).

Synthesis Example 3 (Synthesis of 2,6-difluoro-1,5-diiodobiphenylene) (Step C1)
In a nitrogen atmosphere, 2.08 mg (20.5 mmol) of diisopropylamine and 60 ml of THF (dehydrated grade) were added to a 300 ml Schlenk reaction vessel. This mixture was cooled to -55°C, and 12 ml (19.2 mmol) of a hexane solution of n-butyllithium (Kanto Chemical, 1.6 M) was added dropwise to prepare LDA. This mixture was cooled to -78°C, and 1.47 g (7.81 mmol) of 2,6-difluorobiphenylene synthesized in Synthesis Example 2 was added little by little, and the mixture was stirred at -78°C to -65°C for 2 hours. The resulting mixture was brought to -78°C, and a solution consisting of 5.02 g (19.8 mmol) of iodine and 20 ml of THF (dehydrated grade) was added dropwise. The resulting mixture was stirred while gradually increasing the temperature to room temperature. After cooling the reaction mixture to 0°C, water and toluene were added, and the mixture was separated into phases. The aqueous phase was extracted with toluene, and the combined organic phase was washed with saturated saline, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (solvent: hexane), and further recrystallized from hexane/toluene to obtain 769 mg of yellow crystals of 2,6-difluoro-1,5-diiodobiphenylene (yield: 22%). GC analysis showed that the purity was 98.9%.
^1H NMR ( _CDCl3 ): δ = 6.68 (dd, J = 7.3 Hz, 3.6 Hz, 2H), 6.44 (dd, J = 9.6 Hz, 7.3 Hz, 2H).

Synthesis Example 4 (Synthesis of 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene) (Step D1)
In a nitrogen atmosphere, 752 mg (1.71 mmol) of 2,6-difluoro-1,5-diiodobiphenylene synthesized in Synthesis Example 3, 24.7 mg (0.0352 mol) of dichlorobis(triphenylphosphine)palladium (Wako Pure Chemical Industries), 14.5 mg (0.0761 mmol) of copper iodide (Wako Pure Chemical Industries), 10 ml of toluene, and 15 ml of triethylamine were added to a 100 ml Schlenk reaction vessel. Furthermore, 506 mg (5.15 mmol) of trimethylsilylacetylene (Tokyo Chemical Industry) was added. This mixture was reacted at 25° C. for 3.5 hours. Toluene and water were added to the obtained reaction mixture, and after phase separation, the organic phase was washed with water and dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, and the obtained residue was purified by silica gel column chromatography (solvent: hexane). 641 mg of a yellow solid of 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene was obtained (yield: 99%). GC analysis revealed that the purity was 95.6%.
^1H NMR ( _CDCl3 ): δ = 6.60-6.57 (q, J = 4.1 Hz, 2H), 6.46-6.41 (dd, J = 7.32 Hz, 2H), 0.26 (s, 18H).

Synthesis Example 5 (Synthesis of unsubstituted dithienobiphenylene (Step E1)
In a nitrogen atmosphere, 458 mg (1.20 mmol) of 2,6-difluoro-1,5-bis(trimethylsilylethynyl)biphenylene synthesized in Synthesis Example 4, 1.01 g (4.19 mmol) of sodium sulfide nonahydrate (Wako Pure Chemical Industries), and 15 ml of DMSO (Wako Pure Chemical Industries) were added to a 200 ml eggplant flask. The mixture was heated to 70°C and stirred for 5 hours. The reaction mixture was cooled to 0°C, and water and dichloromethane were added. After phase separation, the organic phase was washed with water and dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent: hexane/dichloromethane) to obtain 161 mg of a yellow solid (yield: 51%). The purity was 83.5% by LC analysis.
MS m/z: 264 (M ⁺ , 100%)
^1H NMR ( _CDCl3 ): δ = 7.30 (d, J = 6.0 Hz, 2H), 7.18 (d, J = 7.8 Hz, 2H), 6.94 (d, J = 5.5 Hz, 2H), 6.65 (d, J = 7.3 Hz, 2H).

Synthesis Example 6 (Synthesis of 2,7-dibromodithienobiphenylene) (Step F1)
In a nitrogen atmosphere, 160 mg (0.61 mmol) of the unsubstituted dithienobiphenylene synthesized in Synthesis Example 5 and 20 ml of THF (dehydrated grade) were added to a 100 ml Schlenk reaction vessel. 1.5 ml (2.40 mmol) of a hexane solution of n-butyllithium (Kanto Chemical, 1.6 M) was added thereto at -83°C, and the mixture was stirred at 25°C for 15 minutes, and then cooled again to -78°C. A solution consisting of 852 mg (2.61 mmol) of dibromotetrachloroethane and 5 ml of THF (dehydrated grade) was added dropwise thereto. After stirring for 5.5 hours, water and toluene were added and the mixture was separated into phases. The organic phase was washed twice with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was washed with methanol and hexane to obtain 164 mg of a yellow solid of 2,7-dibromodithienobiphenylene (yield 64%).
^1H NMR ( _CDCl3 ): δ = 7.02 (dd, J = 7.32 Hz, 0.92 Hz, 2H), 6.96 (d, J = 0.88 Hz, 2H), 6.59 (d, J = 7.32 Hz, 2H).

Example 1 (Synthesis of biphenylene derivative (1-1a, R ⁹ = 4-octylthienyl-2-group) compound 1) (Step G1)
In a nitrogen atmosphere, 55 mg (0.13 mmol) of 2,7-dibromodithienobiphenylene synthesized in Synthesis Example 6, 3 mL of DMF, 0.8 mL (0.40 mmol) of a 0.5 M THF solution of lithium chloride, 127 mg of 2-trimethylstannyl-4-n-octylthiophene synthesized based on the method described in Journal of American Chemical Society 1998, 120 (30), 7643, and 11.7 mg (0.01 mmol) of tetrakis(triphenylphosphine)palladium (Tokyo Chemical Industry) as a catalyst were added to a 50 mL Schlenk reaction vessel, and the mixture was stirred at 100° C. for 3 hours. Under ice cooling, a 1 M aqueous potassium fluoride solution was added, and the mixture was stirred overnight. The reaction solution was suction filtered, and the residue was washed with water and methanol. The resulting residue was purified by silica gel column chromatography (solvent; hexane/toluene=10/0 to 10/5). 50 mg of a yellow solid of the biphenylene derivative (1-1a, compound 1) was obtained (yield: 59%).
^1H NMR (CDCl3): δ = 7.11 (d, J = 1.40 Hz, 2H), 7.08 (dd, J = 3.90, 0.92 Hz, 2H), 6.98 (d, J = 0.92 Hz, 2H), 6.90 (d, J = 1.36 Hz, 2H), 6.63 (d, J = 7.32 Hz, 2H), 2.60 (t, J = 7.76 Hz, 4H), 1.68-1.62 (m, 4H), 1.37-1.26 (m, 20H), 0.89 (t, J = 6.84 Hz, 6H).

Synthesis Example 7 (Synthesis of 2-bromo-1-fluoro-3-iodobenzene)
In a nitrogen atmosphere, 5.76 g (56.9 mmol) of diisopropylamine and 115.0 ml of THF (dehydrated grade) were added to a 500 ml Schlenk reaction vessel. This solution was cooled to -50°C, and 34.0 ml (54.4 mmol) of a hexane solution of n-butyllithium (Tokyo Chemical Industry, 1.6 M) was added dropwise to prepare LDA. This mixture was cooled to -78°C, and 11.5 g (51.8 mmol) of 1-fluoro-3-iodobenzene (Tokyo Chemical Industry) was added, and the mixture was kept at -78°C for 2 hours. A solution of 34.4 g (103.6 mmol) of tetrabromomethane (Tokyo Chemical Industry) dissolved in 160.0 ml of THF (dehydrated grade) was added dropwise to this at -78°C, and the temperature was gradually raised to room temperature. Water and toluene were added to the obtained reaction mixture, and the phases were separated. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (solvent: hexane), and 3.0 g of methanol (Wako Pure Chemical Industries, Ltd.) was added, and the mixture was heated to 50° C. for recrystallization to obtain 7.43 g of a white solid of 2-bromo-1-fluoro-3-iodobenzene (yield: 43.3%).
MS m/z: 302 (M ⁺⁺ 2, 75%), 300 (M ⁺ , 78%), 175 (M ⁺⁺ 2-I, 38%), 173 (M ⁺ -I, 39%), 94 (M ⁺ -BrI, 100%).
^1H NMR ( _CDCl3 ): δ = 7.68-7.64 (m, 1H), 7.12-7.08 (m, 1H), 7.05-7.00 (m, 1H)

Synthesis Example 8 (Synthesis of 2,2'-dibromo-3,6'-difluorobiphenyl) (Step A2)
Under a nitrogen atmosphere, 4.89 g (16.3 mmol) of 1-bromo-3-fluoro-2-iodobenzene (Tokyo Chemical Industry Co., Ltd.) and 50.0 ml of THF (dehydrated grade) were added to a 200 ml Schlenk reaction vessel. The solution was cooled to 0° C., and 8.4 ml (19.8 mmol) of a THF solution of ethyl magnesium chloride (Sigma-Aldrich, 2.0 M) was added dropwise. The mixture was aged at 0° C. for 20 minutes to prepare 1-bromo-3-fluorophenyl-2-magnesium chloride.
Meanwhile, under a nitrogen atmosphere, 3.28 g (24.1 mmol) of zinc chloride (Wako Pure Chemical Industries) and 30 ml of THF (dehydrated grade) were added to another 300 ml Schlenk reaction vessel, and cooled to 0° C. The previously prepared 1-bromo-3-fluorophenyl-2-magnesium chloride solution was added dropwise to the resulting white fine slurry solution using a Teflon (registered trademark) cannula, and the 100 ml Schlenk reaction vessel and the Teflon (registered trademark) cannula were further washed with 2 ml of THF (dehydrated grade) and charged into the vessel. The resulting mixture was stirred while gradually increasing the temperature to room temperature. To the resulting slurry of 1-bromo-3-fluorophenyl-2-zinc chloride, 3.51 g (11.7 mmol) of 2-bromo-1-fluoro-3-iodobenzene synthesized in Synthesis Example 9 and 1.40 g (1.2 mmol, 10 mol% relative to 2-bromo-1-fluoro-3-iodobenzene) of tetrakis(triphenylphosphine)palladium (Tokyo Chemical Industry Co., Ltd.) were added as a catalyst. After the reaction was carried out at 60°C for 3 hours, the reaction was stopped by cooling the vessel with water and adding 1M hydrochloric acid. Toluene was added, and the organic phase was separated and dried with anhydrous sodium sulfate. The mixture was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent: hexane). 2.90 g of a colorless solid of 2,2'-dibromo-3,6'-difluorobiphenyl was obtained (yield 71.3%).
^1H NMR ( _CDCl3 ): δ = 7.50 (d, J = 8.2 Hz, 1H), 7.42-7.36 (m, 1H), 7.33-7.26 (m, 1H), 7.23-7.18 (m, 1H), 7.17-7.12 (m, 1H), 7.05-6.96 (d, J = 7.3 Hz, 1H).

Synthesis Example 9 (Synthesis of 1,5-difluorobiphenylene) (Step B2)
In a nitrogen atmosphere, 395.5 mg (1.1 mmol) of 2,2'-dibromo-3,6'-difluorobiphenyl synthesized in Synthesis Example 8 and 20 ml of THF (dehydrated grade) were added to a 100 ml Schlenk reaction vessel. The mixture was cooled to -78°C, and 2.9 ml (4.6 mmol) of a hexane solution of n-butyllithium (Kanto Chemical, 1.6 M) was added dropwise. The mixture was aged at -78°C for 1 hour, then heated to -40°C over 10 minutes and aged for 1 hour. 1.50 g (4.8 mmol) of N-fluorobenzenesulfonimide (Tokyo Chemical Industry) was added thereto. The resulting mixture was stirred while gradually warming to room temperature. 1 M hydrochloric acid was added to the reaction mixture, and toluene was added to separate the phases. The organic phase was dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent: hexane). A pale yellow solid of 1,5-difluorobiphenylene was obtained in an amount of 130.0 mg (yield: 51.7%).
MS m/z: 188 (M ⁺ , 100%), 168 (M ⁺ -HF, 15%) 94 (M ⁺ -C ₆ H ₃ F, 15%).
^1H NMR ( _CDCl3 ): δ = 6.80 (ddd, 2H) δ = 6.56-6.50 (m, 4H).

Synthesis Example 10 (Synthesis of biphenylene-1,5-bis(thioacetaldehyde dimethyl acetal) (Step C2)
In a nitrogen atmosphere, 57.6 mg (0.31 mmol) of 1,5-difluorobiphenylene synthesized in Synthesis Example 9, 398.0 mg (1.65 mmol) of sodium sulfide nonahydrate (Wako Pure Chemical Industries), and 4 ml of NMP (Wako Pure Chemical Industries) were added to a 100 ml Schlenk reaction vessel. The mixture was stirred at 110° C. for 6 hours. 578.2 mg (3.42 mmol) of 2-bromoacetaldehyde dimethyl acetal (Tokyo Chemical Industry) was added to the resulting reaction mixture, and the mixture was heated and stirred at 100° C. for 3 hours. The resulting reaction mixture was cooled to room temperature, and water and toluene were added. After phase separation, the organic phase was dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent; hexane/ethyl acetate=10/1 to 10/2). Further, low boiling points were removed under reduced pressure to obtain 65.4 mg of a yellow solid of biphenylene-1,5-bis(thioacetaldehyde dimethyl acetal) (yield 64.7%).
^1H NMR ( _CDCl3 ): δ = 6.70 (d, J = 5.5 Hz, 2H), 6.69 (d, J = 1.4 Hz, 2H), 6.54 (dd, J = 5.5 Hz, 1.4 Hz, 2H), 4.53 (t, J = 5.9 Hz, 2H), 3.38 (s, 12H), 3.10 (d, J = 5.9, Hz, 4H).

Synthesis Example 11 (Synthesis of unsubstituted dithienobiphenylene) (Step D2)
In a nitrogen atmosphere, 57.7 mg (0.15 mmol) of biphenylene-1,5-bis(thioacetaldehyde dimethyl acetal) synthesized in Synthesis Example 10, 109.4 mg of polyphosphoric acid (Wako Pure Chemical Industries), and 4 ml of chlorobenzene (Wako Pure Chemical Industries) were added to a 50 ml Schlenk reaction vessel. The mixture was stirred at 130° C. for 5 hours. The reaction mixture was cooled to room temperature, and water and toluene were added. After phase separation, the organic phase was washed with water and dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, and the resulting residue was purified by silica gel column chromatography (solvent; hexane/ethyl acetate=10/1 to 10/2), to obtain 22.5 mg of a yellow solid of a dithienobiphenylene derivative (yield 55%).

Synthesis Example 12 (Synthesis of 2,7-dibromodithienobiphenylene) (Step F2)
In a nitrogen atmosphere, 22 mg (0.083 mmol) of the unsubstituted dithienobiphenylene synthesized in Synthesis Example 11 and 3 ml of THF (dehydrated grade) were added to a 50 ml Schlenk reaction vessel. 0.21 ml (0.33 mmol) of a hexane solution of n-butyllithium (Kanto Chemical, 1.6 M) was added thereto at -83°C, and the mixture was stirred at 25°C for 15 minutes, and then cooled again to -78°C. A solution consisting of 117 mg (0.36 mmol) of dibromotetrachloroethane and 2 ml of THF (dehydrated grade) was added dropwise thereto. After stirring for 5.5 hours, water and toluene were added and the mixture was separated into phases. The organic phase was washed twice with water, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The resulting residue was washed with methanol and hexane to obtain 21 mg of a yellow solid of 2,7-dibromodithienobiphenylene (yield 60%).
^1H NMR ( _CDCl3 ): δ = 7.07 (d, J = 7.5 Hz, 2H), 7.05 (s, 2H), 6.64 (d, J = 7.5 Hz, 2H).

Example 2 (Synthesis of biphenylene derivative (1-2a, R ⁹ = 4-octylthienyl-2-group, compound 2)) (Step G2)
In a nitrogen atmosphere, 21 mg (0.050 mmol) of 2,7-dibromodithienobiphenylene synthesized in Synthesis Example 12, 3 mL of DMF, 0.4 mL (0.20 mmol) of a 0.5 M THF solution of lithium chloride, 120 mg of 2-trimethylstannyl-4-n-octylthiophene synthesized in the same manner as in Example 1, and 5.0 mg (0.005 mmol) of tetrakis(triphenylphosphine)palladium (Tokyo Chemical Industry) as a catalyst were added to a 50 mL Schlenk reaction vessel, and the mixture was stirred at 100° C. for 3 hours. Under ice cooling, a 1 M aqueous potassium fluoride solution was added, and the mixture was stirred overnight. The reaction solution was suction filtered, and the residue was washed with water and methanol. The resulting residue was purified by silica gel column chromatography (solvent; hexane/toluene=10/0 to 10/5). 20 mg of a yellow solid of a biphenylene derivative (1-2a, compound 2) was obtained (yield 61%).

Example 3 (Preparation of solution for forming organic semiconductor layer)
In air, 0.87 mg each of Compounds 1 and 2 synthesized in Examples 1 and 2 and 434 mg of toluene (Wako Pure Chemical Industries, Pure Grade) were added to a 10 ml sample tube, and the mixture was heated and dissolved at 50° C., and then allowed to cool to room temperature (25° C.) to prepare a solution for forming an organic semiconductor layer. The solution state was maintained even after 10 hours at 25° C. (compound concentration was 0.20 wt %), and it was confirmed that the compound is suitable for film formation by drop casting and inkjet.

Example 4 (Fabrication of organic semiconductor layer and organic thin film transistor)
A top gate-bottom contact type p-type organic thin film transistor was produced using the organic semiconductor layer forming solution obtained in Example 3. The materials of each component and the film formation method are shown in Table 1.

First, the organic semiconductor layer forming solution obtained in Example 3 was filled into a syringe, and the solution was passed through a 0.2 μm filter and drop-cast in air. The solution was naturally dried at room temperature (25° C.) to prepare a thin film.
A shadow mask with a channel length of 50 μm and a channel width of 500 μm was placed on the organic semiconductor layer, and gold was vacuum-deposited to form source and drain electrodes, thereby producing a bottom-gate-top-contact type p-type organic thin-film transistor.
The electrical properties of the fabricated organic thin-film transistor were evaluated using a semiconductor parameter analyzer (Keithley 4200SCS) by scanning the gate voltage (Vg) from +5 to -70 V in 1 V increments at a drain voltage (Vd = -50 V). Furthermore, the electrical properties of this organic thin-film transistor were measured after annealing at 130°C for 15 minutes. The results of the electrical properties are shown in Table 2. Almost no deterioration in performance due to the heat treatment was observed.

Comparative Example 1
(Preparation of solution for forming organic semiconductor layer)
A solution for forming an organic semiconductor layer was prepared in a 10 ml sample tube under air using 2,7-dioctylbenzothienobenzothiophene (Sigma-Aldrich) in the same manner as in Example 3. The solution state was maintained (0.20 wt %) even after 10 hours at 25° C., and it was confirmed that the compound is suitable for film formation by drop casting and inkjet.

(Fabrication of organic semiconductor layer and organic thin film transistor)
Using this organic semiconductor layer-forming solution, a 60 nm-thick thin film of 2,7-dioctylbenzothienobenzothiophene was formed in the same manner as in Example 4, and a bottom-gate-top-contact type p-type organic thin film transistor was fabricated.
The transfer characteristics of the transistor element were evaluated, and the carrier mobility of holes was found to be 0.01 cm ² /V·sec, and the current on/off ratio was found to be 3.0×10 ⁵ .
Furthermore, the electrical properties of this organic thin-film transistor were measured after annealing it at 150° C. for 15 minutes. As a result, no transistor operation was obtained, and a significant decrease in performance due to the heat treatment was observed. Microscopic observation confirmed that the organic semiconductor layer was destroyed by heating.

Comparative Example 2
(Fabrication of organic semiconductor layer and organic thin film transistor)
The same operations as in Comparative Example 1 were repeated except that the organic thin film transistor prepared in Comparative Example 1 was annealed at 130° C. for 15 minutes. As a result, transistor operation was not obtained, and a significant decrease in performance due to the heat treatment was observed. Microscopic observation confirmed that the organic semiconductor layer was destroyed by heating.

The biphenylene derivative of the present invention provides high carrier mobility and has excellent heat resistance and solubility, and is therefore expected to be used as a material for semiconductor devices, such as organic thin-film transistors.

(A): bottom gate-top contact type organic thin film transistor (B): bottom gate-bottom contact type organic thin film transistor (C): top gate-top contact type organic thin film transistor (D): top gate-bottom contact type organic thin film transistor 1: organic semiconductor layer 2: substrate 3: gate electrode 4: gate insulating layer 5: source electrode 6: drain electrode

Claims (8)

A biphenylene derivative represented by the following general formula (1):
[(Here, A represents a covalent bond, and one of the combinations of adjacent two of R ¹ to R ⁴ and one of the combinations of adjacent two of R ⁵ to R ⁸ constitute the following general formula (2) to form a 4- to 5-membered ring. R ¹ to R ⁸ that do not constitute the following general formula (2) each independently represent one of the group consisting of hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, or an aryl group having 4 to 26 carbon atoms, and the hydrogen of the alkyl group, alkenyl group, alkynyl group, or aryl group may be substituted with fluorine.)
(wherein, X ^is one of the group consisting of a covalent bond, oxygen, sulfur, and selenium; Y is ^CR13 or nitrogen; n is 1 or 2; R9 is one of the group consisting of a fluorine-substituted alkyl group having 1 to 20 carbon atoms and a heteroaryl-2-group having 5 to 26 carbon atoms and a substituent at the 4-position; and R13 is one of the group consisting of ^hydrogen , fluorine, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group .) The biphenylene derivative according to claim 1, characterized in that n is 1. The biphenylene derivative according to claim 1, wherein Y is ^CR13 . The biphenylene derivative according to any one of claims 1 to 3, characterized in that X is sulfur. 5. The biphenylene derivative according to claim 1, wherein R ⁹ is one member of the group consisting of a fluorine-substituted alkyl group having 1 to 20 carbon atoms and a heteroaryl-2- group having 5 to 26 carbon atoms and having a substituent at the 4-position. A solution for forming an organic semiconductor layer, comprising the biphenylene derivative according to any one of claims 1 to 5. An organic semiconductor layer formed using the organic semiconductor layer forming solution according to claim 6. An organic thin-film transistor comprising the organic semiconductor layer according to claim 7.