JP2015179835A - Organic thin-film transistor and organic electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin-film transistor which has small variation in characteristics, and high carrier mobility.SOLUTION: The organic thin-film transistor includes a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film. The organic semiconductor film contains an organic semiconductor represented by general formula (1). The interfacial energy between a material used for the gate insulating film and the organic semiconductor is 2.0 mJ/mor less. The organic semiconductor film is obtained by deposition using a printing process.

Description

  The present invention relates to an organic thin film transistor and an organic electronic device, and more particularly to an organic thin film transistor and an organic electronic device that have high carrier mobility and small performance variations such as threshold voltage.

  Organic semiconductor devices typified by organic thin film transistors have attracted attention in recent years because they have features not found in inorganic semiconductor devices such as energy saving, low cost, and flexibility.

  This organic semiconductor device is composed of several kinds of materials such as an organic semiconductor layer, a substrate, an insulating layer, and an electrode. Among them, the organic semiconductor layer responsible for charge carrier movement has a central role of the device.

  And since the performance of an organic semiconductor device is influenced by the carrier mobility of the organic material which comprises this organic-semiconductor layer, the appearance of the organic material which gives a high carrier mobility is desired.

  As a method for producing an organic semiconductor layer, generally known are a vacuum deposition method in which an organic material is vaporized under a high temperature vacuum, and a coating method in which an organic material is dissolved in an appropriate solvent and applied. It has been. Since the coating can be carried out using printing technology without using high-temperature and high-vacuum conditions, it is considered to be an economically preferable process, and an organic semiconductor layer having high coating properties and excellent carrier mobility. It is desired.

  In addition, conventionally known printing type organic thin film transistors have an important problem of large variations in performance (see, for example, Patent Documents 1 and 2), and printing type organic thin film transistors with small performance variations are desired. It is rare. In general, carrier mobility and performance variations are in a trade-off relationship, and low-molecular semiconductors with high crystallinity tend to achieve high mobility, while performance variations tend to be large. It becomes a trend.

  A print-type organic thin film transistor is known in which, by using a specific low molecular weight semiconductor, variation in carrier mobility is reduced among various performances of the organic thin film transistor (see, for example, Patent Document 3). However, the printing type organic thin film transistor described in Patent Document 3 has a process limitation because it is necessary to convert the molecular structure by an external stimulus such as heat after forming the organic semiconductor film by printing. . Patent Document 3 does not describe any threshold voltage important as the performance of the organic thin film transistor.

  Realization of printed organic TFTs with small variations in performance including high carrier mobility and threshold voltage is indispensable for device applications.

JP 2011-233724 A JP 2008-066439 A JP 2013-201363 A

  The present invention has been made in view of the above problems, and has as its object the organic thin film transistor having a high carrier mobility and a small performance variation such as a threshold voltage, an organic thin film transistor array using the organic thin film transistor, and an electronic device Is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have found that an organic thin film transistor having high carrier mobility and small performance variations such as a threshold voltage can be formed, and the present invention has been completed.

  That is, the present invention is an organic thin film transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film, wherein the organic semiconductor film has the general formula (1)

[Wherein, R ^{1 to} R ⁶ are each independently a hydrogen atom, 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 1 to 1 carbon atoms. 20 alkoxy groups, C1-C20 alkylthio groups, C1-C20 haloalkyl groups, C3-C10 cycloalkyl groups, C6-C14 aryl groups, and 3- to 12-membered cyclohetero heterocycles An alkyl group, a 5- to 14-membered heteroaryl group, or general formula (2)

(In the formula, R ⁷ represents a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, a cycloheteroalkyl group having 3 to 12 members, or a heteroaryl group having 5 to 14 members. Y represents a divalent alkyl group having 1 to 6 carbon atoms or a divalent haloalkyl group having 1 to 6 carbon atoms.)
The group represented by these is shown. ]
The interface energy between the material used for the gate insulating film and the organic semiconductor is 2.0 mJ / m ² or less, and the organic semiconductor film is formed by a printing process. It is related with the organic thin-film transistor characterized by the above-mentioned.

  The present invention also relates to an organic thin film transistor, wherein the printing process is a printing process selected from dispenser printing, inkjet printing, offset printing, relief printing, intaglio printing, gravure printing, slit coat printing, or screen printing. Is.

  The present invention also relates to an organic thin film transistor array obtained using the organic thin film transistor, a differential amplifier circuit, and an organic electronic device using the differential amplifier circuit.

  The present invention is described in detail below.

  There is no particular limitation on the gate electrode used in the organic thin film transistor of the present invention, for example, aluminum, gold, silver, copper, highly doped silicon, tin oxide, indium oxide, indium tin oxide, molybdenum oxide, chromium, titanium, Examples thereof include inorganic materials such as tantalum, chromium, graphene, and carbon nanotube; and organic materials such as a doped conductive polymer (eg, PEDOT-PSS).

The gate insulating film used in the organic thin film transistor of the present invention has an interface energy between the material used for the gate insulating film and the organic semiconductor of 2.0 mJ / m ² or less, preferably 1.8 mJ / m ² or less. And more preferably 0.001 to 1.5 mJ / m ² . By setting the interface energy within the above range, the organic semiconductor film formed on the surface of the gate insulating film can be obtained as a uniform crystal (layered crystal), and performance variations such as threshold voltage in the organic thin film transistor are reduced. .

  In the present invention, the interfacial energy between the material used for the gate insulating film and the organic semiconductor is calculated by the following equation (a).

γ ₁₂ = γ ₁ + γ ₂ − (γ ₁ ^d γ ₂ ^d ) ^1/2 -2 (γ ₁ ^p γ ₂ ^p ) ^1/2 (a)
(Where γ ₁₂ is the interfacial energy, γ ₁ is the surface energy of the material used for the gate insulating film, γ ₁ ^d is the dispersion force of the material used for the gate insulating film, and γ ₁ ^p is the material used for the gate insulating film. Γ ₂ is the surface energy of the organic semiconductor, γ ₂ ^d is the dispersion force of the organic semiconductor, and γ ₂ ^p is the polar component of the organic semiconductor, and these values are the values of the gate insulating film and the organic semiconductor material, respectively. Using a thin film, the contact angle of water and the contact angle of iodomethane are measured by the θ / 2 method, and can be calculated by the Owens-Wendt method.

  In the present invention, the material used for the gate insulating film can be a vapor deposition type material or a coating type material. Here, “evaporation type material” refers to a material obtained as a gate insulating film by vapor deposition, and “coating type material” refers to a material obtained as a gate insulating film by coating. In general, vapor deposition materials are very difficult to obtain from the coating process because of the low solubility of the material before vapor deposition in the solvent, and because the vapor pressure of the material before vapor deposition is low. It is very difficult to obtain from the deposition process.

  In the present invention, a coating process can be adopted in the production of the gate insulating film, and the material used for the gate insulating film is a coating type material because it is suitable for producing an organic thin film transistor with high productivity. Is preferred. Among coating-type materials, the curing of the coating liquid after coating can be used as a crosslinking operation, and it is more suitable for producing an organic thin film transistor with high productivity. Or it is more preferable that it is a coating type material (organic coating type material) obtained using the organic polymer which has a crosslinking point. Here, the crosslinking operation can be performed by heat or light treatment after coating the organic low molecule having the crosslinking point or the organic polymer having the crosslinking point.

  In the present invention, when using a vapor deposition type material, it is preferable that it is a vapor deposition type material (organic vapor deposition type material) obtained by vapor-depositing an organic low molecule from the viewpoint of easy film thickness control.

The material used for the gate insulating film is not particularly limited as long as the interface energy with the organic semiconductor is 2.0 mJ / m ² or less. Specifically, for example, an inorganic coating material using a coating type inorganic oxide; a crosslinked polymethyl methacrylate resin, a crosslinked polymethyl acrylate resin, a crosslinked polyimide resin (polyamic acid having a cyclization point) As a precursor, the amic acid group in the polyamic acid undergoes a dehydration cyclization reaction, thereby providing a solvent-resistant crosslinked polyimide resin), a crosslinked polycarbonate resin, a crosslinked poly (diisopropyl fumarate) resin, a crosslinked resin. Poly (diethyl fumarate) resin, crosslinked polyethylene terephthalate resin, crosslinked polyethylene naphthalate resin, crosslinked polyethersulfone resin, crosslinked cyclic polyolefin resin, crosslinked polystyrene resin, crosslinked poly-α-methylstyrene resin, Crosslinked polyethylene resin, crosslinked polypropylene resin, crosslinked poly ( Organic coating type materials such as (ethylene-propylene) copolymer resin, crosslinked poly (ethylene-norbornene) copolymer resin, BCB resin (substance before coating: bisvinylsiloxane benzocyclobutene (BCB)); vapor deposition type Inorganic vapor-deposited materials using inorganic oxides: poly (paraxylylene) (substance before vapor deposition: diparaxylylene), poly (chloroparaxylylene) (substance before vapor deposition: dichlorodiparaxylylene), poly (dichloroparaxylylene) Organic vapor deposition type materials such as (len) (substance before vapor deposition: tetrachlorodiparaxylylene).

  In the present invention, the BCB resin is particularly preferable as the coating material because it is an organic coating material and is suitable for obtaining an organic thin film transistor having a smaller interface energy and a small variation in performance. Further, as the vapor deposition type material, poly (chloroparaxylylene) is particularly preferable because it is an organic vapor deposition type material and is suitable for obtaining an organic thin film transistor with smaller interface energy and smaller performance variation.

  When using an organic coating material for the gate insulating film, for example, a film coated by dissolving in a solvent such as chloroform, toluene, xylene, tetrahydrofuran, propylene glycol, propylene glycol 1-monomethyl ether 2-acetate, methyl ethyl ketone, cyclohexanone Can be used as a gate insulating film.

  The surface of the gate insulating film is, for example, octadecyltrichlorosilane, decyltrichlorosilane, decyltrimethoxysilane, octyltrichlorosilane, octadecyltrimethoxysilane, β-phenethyltrichlorosilane, β-phenethyltrimethoxysilane, phenyltrichlorosilane, Silanes such as phenyltrimethoxysilane and phenyltriethoxysilane; even those modified with silylamines such as hexamethyldisilazane can be used.

  In general, the surface treatment of the gate insulating film increases the crystal grain size and molecular orientation of the material constituting the organic semiconductor film, thereby improving the carrier mobility and current on / off ratio. A favorable result is obtained that the threshold voltage is reduced.

  The material of the source electrode and the drain electrode used in the organic thin film transistor of the present invention is not particularly limited, and the same material as the gate electrode can be used, which may be the same as or different from the material of the gate electrode, Different materials may be stacked. In order to increase the carrier injection efficiency, surface treatment can be performed on these electrode materials. Examples of the surface treatment agent for the electrode material include benzenethiol and pentafluorobenzenethiol.

  When performing the surface treatment of the electrode, the surface treatment agent may be diluted with a solvent. There is no particular limitation on the solvent to be diluted. For example, alcohol solvents such as methanol, ethanol, 2-propanol; o-dichlorobenzene, chlorobenzene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chloroform Halogen solvents such as THF; tetrahydrofuran solvents such as THF (tetrahydrofuran) and dioxane; hydrocarbon solvents such as toluene, xylene and mesitylene; ester solvents such as ethyl acetate and γ-butyrolactone; N, N- Examples thereof include amide solvents such as dimethylformamide and N-methylpyrrolidone.

  The organic semiconductor film used in the organic thin film transistor of the present invention includes a specific organic semiconductor.

  The organic semiconductor has the following general formula (1)

It has the structure represented by these.
In formula (1), R ^{1 to} R ⁶ are each independently a hydrogen atom; methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, An alkyl group having 1 to 20, preferably 4 to 8 carbon atoms such as an isobutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an n-heptyl group and an n-octyl group; an ethenyl group and a propenyl group Group, butenyl group, pentenyl group, hexenyl group, butadienyl group, pentadienyl group, hexadienyl group and the like, an internal or terminal alkenyl group having 2 to 20, preferably 4 to 8 carbon atoms; ethynyl group, propenyl group, butynyl group, pentynyl An internal or terminal alkynyl group having 2-20 carbon atoms, preferably 4-8, such as a group; methoxy group, ethoxy group, n-propoxy group, iso An alkoxy group having 1 to 20 carbon atoms, such as a lopoxy group or a tert-butoxy group, preferably 4 to 8 carbon atoms; a carbon number such as a methylthio group, an ethylthio group, an n-propylthio group, an isopropylthio group, or a tert-butylthio group. -20, preferably 4-8 alkylthio groups; one such as trifluoromethyl group, pentafluoroethyl group, difluoromethyl group, fluoromethyl group, trichloromethyl group, dichloromethyl group, chloromethyl group, pentachloroethyl group A haloalkyl group having 1 to 20 carbon atoms, preferably 4 to 8 carbon atoms having the above halogen substituents; cyclopropyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopentenyl group, cyclohexenyl group, cyclohexadienyl group, Cycloheptatrienyl group, norbornyl group, C3-C10 cycloalkyl group such as vinyl group, norcalyl group, adamantyl group, spiro [4,5] decanyl group; carbon such as phenyl group, 1-naphthyl group, 2-naphthyl group, anthracenyl group, phenanthrenyl group Aryl group having 6 to 14, preferably 6 to 10; 3 to 12 membered, preferably 4 to 8 membered cycloheteroalkyl group, 5 to 14 membered, preferably 5 to 8 membered heteroaryl Group or general formula (2)

(In the formula, R ⁷ is a cycloalkyl group having 3 to 10 carbon atoms, preferably 4 to 8 carbon atoms, an aryl group having 6 to 14 carbon atoms, preferably 6 to 10 carbon atoms, and a 3 to 12 membered ring, preferably 4 -8-membered cycloheteroalkyl group, or 5- to 14-membered ring, preferably 5- to 8-membered heteroaryl group, Y is a divalent alkyl group having 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms Or an alkylaryl group such as a benzyl group; an alkylcycloheteroalkyl group; an alkylheteroaryl represented by the following formula: or a divalent haloalkyl group having 1 to 6 carbon atoms, preferably 2 to 4 carbon atoms. Indicates a group or the like.

In addition, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C3-C10 cycloalkyl group, a C6-C14 aryl group, The 12-membered cycloheteroalkyl group or the 5- to 14-membered heteroaryl group includes 1 to 4 halogen atoms, a cyano group, a nitro group, an oxo group, a hydroxyl group, NH ₂ , and an amino acid having 1 to 20 carbon atoms. Group, arylamino group having 6 to 14 carbon atoms, sulfonyl group, formyl group, alkylcarbonyl group having 1 to 20 carbon atoms, arylcarbonyl group having 6 to 14 carbon atoms, carbonyl group, alkyloxocarbonyl having 1 to 20 carbon atoms Group, C6-C14 aryloxocarbonyl group, imide group, C1-C20 alkylimide group, C6-C14 arylimide group, thioimide group, C1 20 alkylthioimide groups, C6-C14 arylthioimide groups, sulfonylimide groups, C1-C20 alkylsulfonylimide groups, C6-C14 arylsulfonylimide groups, silyl groups, C1-C1 20 alkylsilyl groups, C1-20 alkyl groups, C2-20 alkenyl groups, C2-20 alkynyl groups, C1-20 alkoxy groups, C1-20 alkylthio groups , A haloalkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a haloaryl group, a cycloheteroalkyl group having 3 to 12 members and / or 5 to 14 members It may be substituted with a ring heteroaryl group.

  The organic semiconductor represented by the formula (1) can obtain an organic thin film transistor having a high solubility and a smaller performance variation such as a threshold value.

It is preferable that it is a structure represented by these.

In formula (3), R ¹ and R ² are each independently a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, an alkyl group having 1 to 20 carbon atoms, preferably 4 to 8 carbon atoms such as an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an n-heptyl group, and an n-octyl group; a methoxy group, an ethoxy group, and an n- An alkoxy group having 1 to 20 carbon atoms, preferably 4 to 8 carbon atoms, such as a propoxy group, an isopropoxy group, a tert-butoxy group and the like, and a more preferable structure in the present invention include a compound represented by the general formula (3): R ¹ and R ² are each independently an alkyl group having 1 to 20 carbon atoms, preferably 4 to 8 carbon atoms.

  Specific examples of the organic semiconductor used in the present invention include 2,7-di (n-methyl) dithienobenzodithiophene, 2,7-di (n-ethyl) dithienobenzodithiophene, 2,7-di (N-propyl) dithienobenzodithiophene, 2,7-di (isopropyl) dithienobenzodithiophene, 2,7-di (n-butyl) dithienobenzodithiophene, 2,7-di (sec-butyl) ) Dithienobenzodithiophene, 2,7-di (tert-butyl) dithienobenzodithiophene, 2,7-di (isobutyl) dithienobenzodithiophene, 2,7-di (n-pentyl) dithienobenzo Dithiophene, 2,7-di (isopentyl) dithienobenzodithiophene, 2,7-di (neopentyl) dithienobenzodithiophene, 2,7-di (n-hexyl) dithi Nobenzodithiophene, 2,7-di (n-heptyl) dithienobenzodithiophene, 2,7-di (n-octyl) dithienobenzodithiophene, 2,7-di (n-decyl) dithienobenzo Dithiophene, 2,7-di (n-dodecyl) dithienobenzodithiophene, 2,7-di (n-tetradecyl) dithienobenzodithiophene, 2,7-di (ethenyl) dithienobenzodithiophene, 2, , 7-di (propenyl) dithienobenzodithiophene, 2,7-di (butenyl) dithienobenzodithiophene, 2,7-di (pentenyl) dithienobenzodithiophene, 2,7-di (hexenyl) di Thienobenzodithiophene, 2,7-di (butadienyl) dithienobenzodithiophene, 2,7-di (pentadienyl) dithienobenzodithiophene, 2, -Di (hexadienyl) dithienobenzodithiophene, 2,7-di (ethynyl) dithienobenzodithiophene, 2,7-di (propenyl) dithienobenzodithiophene, 2,7-di (butynyl) dithienobenzo Dithiophene, 2,7-di (pentynyl) dithienobenzodithiophene, 2,7-di (methoxy) dithienobenzodithiophene, di (ethoxy) dithienobenzodithiophene, 2,7-di (n-propoxy) ) Dithienobenzodithiophene, 2,7-di (isopropoxy) dithienobenzodithiophene, 2,7-di (tert-butoxy) dithienobenzodithiophene, and the like.

  The organic semiconductor film in the organic thin film transistor of the present invention is formed by a printing process. By forming an organic semiconductor film by a printing process, it is possible to form an organic thin film transistor that not only exhibits high productivity but also has high carrier mobility and small variation in threshold voltage.

  Such an organic semiconductor film can be manufactured, for example, by printing on a substrate of an organic semiconductor represented by the general formula (1). At this time, after the organic semiconductor solution is printed on the substrate, the organic semiconductor film is formed by vaporizing the solvent by a method such as heating, airflow and / or natural drying.

  There is no restriction | limiting in particular in the solvent which melt | dissolves the organic semiconductor used by this invention. For example, halogen solvents such as o-dichlorobenzene, chlorobenzene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane and chloroform; ether solvents such as THF and dioxane; aroma such as toluene, xylene and mesitylene Hydrocarbon solvents of group compounds; ester solvents such as ethyl acetate and γ-butyrolactone; amide solvents such as N, N-dimethylformamide and N-methylpyrrolidone. These solvents may be used alone or as a mixture of two or more. Among these, chlorobenzene, toluene, mesitylene, and tetralin are preferable because the organic semiconductor used in the present invention has high solubility and is used in a general printing process.

  The concentration of the organic semiconductor in the solution is not particularly limited, but is preferably 0.01 to 10.0% by weight and more preferably 0.05 to 7% by weight from the solubility of the organic semiconductor and the efficiency of the printing process. Although the temperature at the time of printing is not particularly limited, it is not necessary to use a special device at the time of printing.

  When the organic semiconductor film is produced according to the present invention, the printing process can be either plate printing or plateless printing. The printing process is not particularly limited as long as the organic semiconductor film can be crystallized after applying the organic semiconductor solution to the substrate. However, high productivity and patterning can be performed. From the viewpoint of ease, dispenser printing, ink jet printing, offset printing, relief printing, intaglio printing, gravure printing, slit coat printing, and screen printing are preferred.

  Among these, dispenser printing, inkjet printing, offset printing, letterpress printing, and slit coat printing are more preferable from the viewpoint of mass productivity and accuracy.

  As a structure of an organic thin film transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film, for example, a cross-sectional structure shown in FIG.

  In FIG. 1, (A) bottom gate-top contact type, (B) bottom gate-bottom contact type, (C) top gate-top contact type, and (D) top gate-bottom contact type organic thin film transistor. In FIG. 1, 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.

  Specific examples of substrates that can be used for organic thin film transistors include, for example, polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polymethyl acrylate, polyethylene, polypropylene, polystyrene, cyclic polyolefin, fluorinated cyclic polyolefin, polyimide, polycarbonate, Plastic substrates such as polyvinylphenol, polyvinyl alcohol, poly (diisopropyl fumarate), poly (diethyl fumarate), poly (diisopropyl maleate), polyethersulfone, polyphenylene sulfide, cellulose triacetate; glass, quartz, aluminum oxide, silicon, Inorganic materials such as highly doped silicon, silicon oxide, tantalum dioxide, tantalum pentoxide, and indium tin oxide Substrate; gold, copper, chromium, titanium, aluminum or the like metal substrate. When highly doped silicon is used for the substrate, the substrate can also serve as the gate electrode according to the present invention.

  The material of the substrate to be used is not particularly limited, and various crystalline and non-crystalline materials can be used. Specific examples of the substrate include, for example, polyethylene terephthalate, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, cyclic polyolefin, polyimide, polycarbonate, polyvinylphenol, polyvinyl alcohol, poly (diisopropyl fumaric acid), poly (diethyl fumaric acid), poly Plastic substrates such as (diisopropylmaleic acid); Inorganic material substrates such as glass, quartz, aluminum oxide, silicon, silicon oxide, tantalum dioxide, tantalum pentoxide, and indium tin oxide; Metal substrates such as gold, copper, chromium, and titanium Etc. The surfaces of these substrates can be used even if they are modified with silanes such as octadecyltrichlorosilane and octadecyltrimethoxysilane; and silylamines such as hexamethyldisilazane. Further, the substrate may be made of an insulating or dielectric material. The solvent after printing can be removed by drying at normal pressure or reduced pressure, and can also be removed by heating or nitrogen flow.

  Generally, when a variation in the threshold voltage of a transistor used in a circuit is confirmed, the operation of the circuit becomes unstable and it is difficult to obtain desired circuit characteristics. In general, in order to obtain stable and desired circuit characteristics, the standard deviation σ, which is an index of variation in threshold voltage of transistors, is used, and circuit design is performed so that stable circuit characteristics can be obtained even at 3σ. Therefore, a transistor having a small standard deviation σ of the threshold voltage is desired. Since the organic thin film transistor of the present invention has a feature that variation in threshold voltage is small, a circuit exhibiting stable operation can be formed by using the organic thin film transistor of the present invention for the circuit.

  The threshold value of the organic thin film transistor of the present invention may be determined by any method as long as it is a generally known method for determining the threshold value of the organic transistor. From the X-axis intercept of a straight line obtained by plotting the square root of the saturation current with respect to the gate voltage.

The organic thin film transistor of the present invention is characterized by high carrier mobility. Among them, in order to obtain an organic electronic device having good performance, the mobility is in the range of 0.001 to 100 cm ² / Vs. It is preferable that

In order to obtain a good organic electronic device, an organic thin film transistor has a current on / off ratio of 10 ⁵ or more, that is, a common logarithmic value of a current on / off ratio (hereinafter, a common logarithm of a current on / off ratio). “Log10AR”) is preferably 5 or more.

  The organic thin film transistor of the present invention is characterized in that variations in threshold voltage are small, and when an organic thin film transistor array is fabricated by arranging a plurality of elements, the threshold value related to the organic thin film transistor array The voltage standard deviation σ is small. Among these, in order to use a minute change in voltage in an organic electronic device, for example, when an organic thin film transistor array is manufactured by arranging 100 or more elements, the standard deviation σ of the threshold voltage related to the organic thin film transistor array is 0. It is preferably .25 or less, more preferably 0.2 or less, and particularly preferably 0.1 or less.

  The organic thin film transistor of the present invention preferably has a small variation in carrier mobility. Further, when an organic thin film transistor array is formed by arranging a plurality of elements, the coefficient of variation CV of carrier mobility related to the organic thin film transistor array = | The standard deviation σ / average value | (hereinafter referred to as “variation coefficient CV (carrier mobility)”) is preferably small. Among these, in order to stably produce an organic thin film transistor array, for example, when an organic thin film transistor array is produced by arranging 100 or more elements, the coefficient of variation CV (carrier mobility) may be 25% or less. More preferably, it is particularly preferably 20% or less.

  The organic thin film transistor of the present invention preferably has a small variation in current on / off ratio. Further, when an organic thin film transistor array is formed by arranging a plurality of elements, the variation coefficient CV of log 10AR related to the organic thin film transistor array = | The standard value σ of log10AR / the average value of log10AR | (hereinafter referred to as “variation coefficient CV (log10AR)”) is preferably small. Among these, in order to produce a stable organic thin film transistor array, for example, when an organic thin film transistor array is produced by arranging 100 or more elements, the coefficient of variation CV (log 10 AR) is more preferably 20% or less, It is particularly preferably 15% or less, and most preferably 10% or less.

  When a differential amplifier circuit is formed using an organic thin film transistor, the amplification degree is preferably 1-1000 in order to obtain higher detection sensitivity.

  According to the present invention, it is possible to provide an organic thin film transistor having high carrier mobility and small performance variations such as a threshold voltage. In addition, by using this organic thin film transistor, it is possible to form an ideal printing type organic thin film transistor array with a small difference in input and output, especially a differential amplifier circuit exhibiting ideal input / output characteristics, which can be applied to various sensors. It becomes possible.

; It is a figure which shows the structure by the cross-sectional shape of an organic thin-film transistor. ; Is a diagram showing a transfer characteristic diagram. ; Is a diagram showing a histogram of mobility. ; Is a diagram showing a histogram of threshold voltage. ; Is a diagram showing a differential amplifier circuit. ; Is a diagram showing a transfer characteristic diagram. ; Is a diagram showing a histogram of mobility. ; Is a diagram showing a histogram of threshold voltage. ; Is a diagram showing a transfer characteristic diagram. ; Is a diagram showing a histogram of mobility. ; Is a diagram showing a histogram of threshold voltage. ; Is a diagram showing a transfer characteristic diagram. ; Is a diagram showing a histogram of mobility. ; Is a diagram showing a histogram of threshold voltage.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Synthesis Example (Synthesis of 1,4-di (3-bromothienyl) -2,5-difluorobenzene)
Under a nitrogen atmosphere, 4.5 ml (3.6 mmol) of a THF solution of isopropylmagnesium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., 0.80 mol / l) and 10 ml of THF were added to a 100 ml Schlenk reaction vessel. The mixture was cooled to −75 ° C., and 873 mg (3.61 mmol) of 2,3-dibromothiophene (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise. After aging at −75 ° C. for 30 minutes, 3.6 ml (3.6 mmol) of a diethyl ether solution of zinc chloride (manufactured by Sigma-Aldrich, 1.0 mol / l) was added dropwise. After the temperature was gradually raised to room temperature, the produced white slurry was concentrated under reduced pressure, and 10 ml of light boiling was distilled off.

To the obtained white slurry (3-bromothienyl-2-zinc chloride), 272 mg (1.00 mmol) of 1,4-dibromo-2,5-difluorobenzene (manufactured by Wako Pure Chemical Industries, Ltd.), tetrakis ( Triphenylphosphine) palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) 39.1 mg (0.0338 mmol, 3.38 mol% with respect to 1,4-dibromo-2,5-difluorobenzene) and 10 ml of THF were added. After carrying out the reaction at 60 ° C. for 8 hours, the vessel was cooled with water and the reaction was stopped by adding 3 ml of 3N hydrochloric acid. Extraction was performed with toluene, and the organic phase was washed with brine and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the resulting residue was purified by silica gel column chromatography (hexane to hexane / dichloromethane = 10/1), recrystallized from hexane / toluene = 6/4, and 1,4-di (3- 227 mg of a light yellow solid of bromothienyl) -2,5-difluorobenzene was obtained (52% yield).
¹ H-NMR (CDCl ₃ , 21 ° C.): δ = 7.44 (d, J = 5.4 Hz, 2H), 7.39 (t, J = 7.8 Hz, 2H), 7.11 (d, J = 5.4 Hz, 2H).
MS m / z: 436 (M ^<+> , 100%), 276 (M ^<+ > ^- 2Br, 13).
(Synthesis of dithienobenzodithiophene)
In a 100 ml Schlenk reaction vessel under a nitrogen atmosphere, 1,4-di (3-bromothienyl) -2,5-difluorobenzene 200 mg (0.458 mmol), NMP 10 ml, and sodium sulfide 9 hydrate (Wako Pure Chemical Industries, Ltd.) 240 mg (1.00 mmol) was added. The resulting mixture was heated at 170 ° C. for 6 hours and the resulting reaction mixture was cooled to room temperature. After adding toluene and water, the phases were separated, and the organic phase was washed with water twice and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the resulting residue was washed twice with hexane to obtain 95 mg of a light yellow solid of dithienobenzodithiophene (yield 69%).
¹ H-NMR (CDCl ₃ , 60 ° C.): δ = 8.28 (s, 2H), 7.51 (d, J = 5.2 Hz, 2H), 7.30 (d, J = 5.2 Hz, 2H).
MS m / z: 302 (M ^<+> , 100%), 270 (M ^<+> -S, 5), 151 (M ^<+ > / 2, 10).
(2,7-di (n-hexanoyl) dithienobenzodithiophene)
To a 100 ml Schlenk reaction vessel were added 86.8 mg (0.286 mmol) of dithienobenzodithiophene and 14 ml of dichloromethane. This mixture was ice-cooled, and 134 mg (1.00 mmol) of aluminum chloride (manufactured by Wako Pure Chemical Industries, Ltd.) and 115 mg (0.858 mmol) of hexanoyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were added. The resulting mixture was stirred at room temperature for 30 hours, then ice-cooled and water was added to stop the reaction. Toluene was added to the resulting slurry mixture for phase separation. The organic phase of the yellow slurry was washed with water and concentrated under reduced pressure. The obtained residue was washed with hexane and methanol and dried under reduced pressure to obtain 99.8 mg of di-n-hexanoyldithienobenzodithiophene as a yellow solid (yield 70%).
¹ H-NMR (heavy benzene, 80 ° C.): δ = 7.73 (s, 2H), 7.26 (s, 2H), 2.58 (t, J = 7.2 Hz, 4H), 1.71 (M, 4H), 1.28 (m, 8H), 0.86 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 498 (M}} +, 100%), 442 (M + -C 4 H 9 +1,46), 427 (M + -C 5 H 11, 13).
(Synthesis of 2,7- (di-n-hexyl) dithienobenzodithiophene)
In a 50 ml Schlenk reaction vessel, 50 mg (0.1 mmol) of di-n-hexanoyldithienobenzodithiophene, 5 mL of THF, 69 mg (0.52 mmol) of aluminum chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were added, and borohydride was cooled with ice. Sodium (38 mg, 1.00 mmol) was slowly added, followed by heating under reflux for 4 hours. After cooling to room temperature, the reaction was stopped by adding water, and toluene was added to the resulting slurry mixture. After toluene and water were separated, water washing of the organic phase was repeated three times. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane / toluene = 10/1), and further recrystallized and purified three times from hexane (pure grade manufactured by Wako Pure Chemical Industries, Ltd.) to obtain 2,7-di (n- Hexyl) dithienobenzodithiophene white solid 28 mg (0.059 mmol) was obtained (yield 59%).
¹ H-NMR (CDCl ₃ ): δ = 8.17 (s, 2H), 7.00 (s, 2H), 2.97 (t, J = 7.2 Hz, 4H), 1.78 (m, 4H), 1.28 (m, 12H), 0.88 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 470 (M}} +, 100%), 399 (M + -C 5 H 11, 57), 328 (M + -2C 5 H 11, 47).
Melting point: 190.2-190.4 ° C.

Example 1
(Flexible substrate)
Polyethylene naphthalate having a thickness of 125 μm (Teonex, manufactured by Teijin DuPont Films Ltd.) was used as a flexible substrate.
(Formation of surface smooth layer)
In a glove box, add 0.5 g of polyvinylphenol (Sigma-Aldrich, Mw-25000) and 4.5 g of propylene glycol 1-monomethyl ether 2-acetate (Kanto Chemical Co., deer special grade) to a 10 mL sample tube. 2 g of the solution obtained by stirring for a period of time, 0.5 g of poly (melamine-co-formaldehyde) (manufactured by Sigma-Aldrich, Mn˜432) and propylene glycol 1-monomethyl ether in a 10 mL sample tube in the glove box Add 0.5 g of 2-acetate (manufactured by Kanto Chemical Co., Ltd., deer special grade) and stir for 10 hours, and mix 0.5 g of the solution obtained by mixing 2 g of the solution on the above flexible substrate. Spin coat film formation (1500 using a spin coater (Mikasa, MS-A100M)) After pm), to form a smooth surface layer of the cross-linked polyvinyl phenol having a thickness of 100nm by a heat treatment of 0.99 ° C. × 60 minutes.
(Formation of gate electrode)
The surface smooth layer formed above was treated with oxygen plasma (100 W, 1 minute) using an oxygen plasma surface treatment apparatus (Plasma Dry Cleaner PC-300, manufactured by Samco), and then an aqueous silver nanoparticle ink solution (DIC Corporation). JAGLT-01) was drawn with an ink jet apparatus using a 10 pL cartridge (Fuji Film Dimatix, DMP-2831, stage temperature 30 ° C.) with a drop interval of 60 μm, and a test chamber (Espec Corp., H- 221, temperature 30 ° C., humidity 95% RH) for 30 minutes, and then fired at 140 ° C. for 60 minutes to form a gate electrode having a thickness of 100 nm and a line width of 400 μm. Here, the plastic substrate on which the gate electrode is formed and the gate insulating film is not formed is referred to as a “plastic substrate with a gate electrode”.
(Formation of gate insulating film)
A film thickness of 550 nm is obtained by vacuum-depositing 0.9 g of dichlorodiparaxylylene (trade name: dix-C) (manufactured by Daisan Kasei Co., Ltd.) on a plastic substrate with a gate electrode using a lab coater (manufactured by Parylene Japan, PDS2010). A poly (chloroparaxylylene) gate insulating film was formed.
(Formation of source / drain electrodes)
Silver nanoparticle ink (NPS-JL, manufactured by Harima Chemical Co., Ltd.) was drawn on the gate insulating film described above using an inkjet device (Fuji Film Dimatix, DMP-2831, stage temperature 50 ° C.) at a dropping interval of 60 μm. Thereafter, the source / drain electrodes having a channel length of 91 μm and a channel width of 1100 μm were formed by baking at 120 ° C. for 60 minutes. Here, the plastic substrate on which the gate electrode, the gate insulating film, and the source / drain electrodes are formed is referred to as “a plastic substrate with an electrode forming gate insulating film”.
(Source / drain electrode modification)
By immersing a plastic substrate with an electrode-forming gate insulating film in a solution (5 mM) of pentafluorobenzenethiol (manufactured by Sigma-Aldrich) and 2-propanol (manufactured by Wako Pure Chemical Industries, Ltd.) for 3 minutes, and then drying. Source / drain electrode modification was performed.
(Formation of partition layer)
The above-mentioned plastic substrate with an electrode-forming gate insulating film is kept at 30 ° C., and a product name: Teflon (registered trademark) (manufactured by DuPont, AF1600) is dispensed onto the dispenser device (manufactured by Musashi Engineering, drawing speed 20 mm / s, discharge) After drawing at a pressure of 7 kPa and a nozzle temperature of 30 ° C., the partition wall layer surrounding the source / drain electrodes having a thickness of 200 nm, a line width of 300 μm, and an inner diameter of 1.1 mm × 2.5 mm is dried in the air for 10 minutes. Formed.
(Formation of organic semiconductor layer and production of organic thin film transistor)
A solution for forming an organic semiconductor layer prepared by adding 3.0 g of toluene and 30 mg of 2,7-di (n-hexyl) dithienobenzodithiophene to a 10 ml sample tube under air and heating to 50 ° C. to dissolve. (Concentration: 1.0% by mass) using a dispenser printing apparatus (manufactured by Musashi Engineering Co., Ltd., drawing speed 20 mm / s, discharge pressure 1 kPa, nozzle temperature 30 ° C.) The organic semiconductor layer was formed by dripping and drying in a) to produce a bottom gate-bottom contact type organic thin film transistor.
(Calculation of interface energy)
The interface energy calculated from the contact angle of water and diiodomethane with 2,7- (n-hexyl) dithienobenzodithiophene, and the contact angle of water and diiodomethane with poly (chloroparaxylylene) is 1 It was ² mJ / m ² .
(Measurement of semiconductor and electrical properties)
Using a semiconductor parameter analyzer (4200-SCS, manufactured by Keithley Co., Ltd.), the electrical properties of the prepared organic thin film transistor are 0.5 V from a drain voltage (V _d = −20 V) to a gate voltage (V _g ) of +10 to −20 V. Scanning was performed in increments to evaluate the transmission physical properties. The carrier mobility was 1.9 cm ² / V · s, the threshold voltage was −0.16 V, and the current on / off ratio was 2.9 × 10 ⁸ .

Example 2
An organic thin film transistor was prepared in the same manner as in Example 1, and an organic thin film transistor array in which 100 organic thin film transistors were arranged was prepared.
(Measurement of semiconductor and electrical properties)
The obtained organic thin film transistor array was subjected to measurement of electrical properties in the same manner as in Example 1. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, in the manufactured organic thin film transistor array, 100 of 100 elements operated as a transistor, the average carrier mobility of the operated 100 elements was 1.1 cm ² / Vs, and the standard deviation σ of carrier mobility was 0.17. Therefore, the coefficient of variation CV (carrier mobility) was 15%. Further, since the average of the common logarithm of the current on / off ratio of 100 elements is 8.0 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.38, the coefficient of variation CV (log10AR) is It was 5%. The average threshold voltage was −0.011 V and the standard deviation σ of the threshold voltage was 0.086.

  FIG. 2 shows a 100-element transfer characteristic diagram, FIG. 3 shows a 100-element mobility histogram, and FIG. 4 shows a 100-element threshold voltage histogram.

  From the above, it was confirmed that very small variation characteristics were exhibited.

Example 3
A differential amplifier circuit was fabricated using an organic thin film transistor fabricated in the same manner as in Example 1. The produced differential amplifier circuit is shown in FIG.
(Measurement of semiconductor and electrical properties)
Using a semiconductor parameter analyzer (4200-SCS, manufactured by Keithley), the constant current source (I _DD ) is set to 500 nA, and the input voltage B (V _INB ) is fixed to any value between 6V and 20V. As a result of measuring the output voltage V _OUTA and V _OUTB when the input voltage A (V _INA ) is swept from 0V to 30V, an ideal input / output characteristic of 0V output voltage difference is shown when the input voltage difference is 0V. The degree was 3.5, and the produced differential amplifier circuit showed appropriate driving.

Example 4
(Formation of gate insulating film)
0% of the solution obtained by mixing 3.0 g of bisvinylsiloxane benzocyclobutene (BCB) (trade name: cycloten 3022-35) (manufactured by Dow Chemical Co.) and 3.0 g of mesitylene in a glove box. Spin coater (500 rpm / 5 seconds and 2000 rpm / 60 seconds) on a plastic substrate with a gate electrode using a spin coater (manufactured by Mikasa Co., Ltd., MS-A100M) using 5 ml, and further 80 ° C. × 3 minutes, A bottom gate is formed in the same manner as in Example 1 except that a 525 nm thick BCB resin obtained by heat treatment at 150 ° C. × 3 minutes, 210 ° C. × 40 minutes, and 250 ° C. × 60 minutes is used as the gate insulating film. A bottom contact type organic thin film transistor was fabricated.
(Calculation of interface energy)
The interfacial energy calculated from the contact angle of water and diiodomethane with 2,7-di (n-hexyl) dithienobenzodithiophene, and the contact angle of water and diiodomethane with BCB resin was 0.35 mJ / m. ² .
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, since the average carrier mobility of the fabricated 100 elements is 0.85 cm ² / Vs and the standard deviation σ of the carrier mobility is 0.15, the coefficient of variation CV (carrier mobility) is 18%. there were. In addition, since the average of the common logarithm of the current on / off ratio of 100 elements is 7.2 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.45, the coefficient of variation CV (log10AR) is It was 6%. The average threshold voltage was −1.5 V, and the standard deviation σ of the threshold voltage was 0.093.

  From the above, it was confirmed that very small variation characteristics were exhibited.

Example 5
(Formation of gate insulating film)
Spin coater (manufactured by Mikasa Corporation, MS-A100M) 0.5 ml of a solution of polyamic acid (precursor of cross-linked polyimide resin) having a cyclization point in a glove box (trade name: CT4112) (manufactured by Kyocera Chemical Co., Ltd.) Is used to form a spin coat film on a plastic substrate with a gate electrode (500 rpm / 5 seconds and 6000 rpm / 120 seconds), and further heat treatment at 80 ° C. × 60 minutes, 120 ° C. × 60 minutes, and 180 ° C. × 60 minutes. A bottom-gate / bottom-contact type organic thin film transistor was produced in the same manner as in Example 1 except that the gate insulating film was a 590 nm-thick crosslinked polyimide-based resin obtained by the above.
(Calculation of interface energy)
The interfacial energy calculated from the contact angle of water and diiodomethane to 2,7-di (n-hexyl) dithienobenzodithiophene, and the contact angle of water and diiodomethane to the above-mentioned crosslinked polyimide resin is 1 0.6 mJ / m ² .
(Measurement of semiconductor and electrical properties)
When an organic thin film transistor array was produced in the same manner as in Example 2 and the electrical properties of the organic thin film transistor array were measured, the average carrier mobility of the produced 100 elements was 0.55 cm ² / Vs, and the carrier Since the standard deviation σ of mobility is 0.051, the coefficient of variation CV (carrier mobility) was 9%. Further, since the average of the common logarithm of the current on / off ratio of 100 elements is 6.4 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.51, the coefficient of variation CV (log10AR) is It was 8%. The average threshold voltage was 5.8 V, and the standard deviation σ of the threshold voltage was 0.19.

  From the above, it was confirmed that very small variation characteristics were exhibited.

Example 6
(Formation of gate insulating film)
Mixing 3.0 g of a polyamic acid (precursor of cross-linked polyimide resin) having a cyclization point in a glove box (trade name: CT4200) (manufactured by Kyocera Chemical) and 3.0 g of N-methyl-2-pyrrolidone Using 0.5 ml of the obtained solution, spin coating was performed on a plastic substrate with a gate electrode using a spin coater (manufactured by Mikasa Co., Ltd., MS-A100M) (500 rpm / 5 seconds and 2500 rpm / 120 seconds). Further, the same as in Example 1 except that a cross-linked polyimide resin having a film thickness of 490 nm obtained by heat treatment at 150 ° C. × 60 minutes, 250 ° C. × 30 minutes, and 320 ° C. × 30 minutes was used as the gate insulating film. A bottom gate-bottom contact type organic thin film transistor was prepared by the method.
(Calculation of interface energy)
The interfacial energy calculated from the contact angle of water and diiodomethane to 2,7-di (n-hexyl) dithienobenzodithiophene, and the contact angle of water and diiodomethane to the above-mentioned crosslinked polyimide resin is 1 0.7 mJ / m ² .
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, since the average carrier mobility of the fabricated 100 elements is 0.42 cm ² / Vs and the standard deviation σ of the carrier mobility is 0.087, the coefficient of variation CV (carrier mobility) is 20%. there were. Further, since the average of the common logarithm of the current on / off ratio of 100 elements is 3.1 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.31, the coefficient of variation CV (log10AR) is 10%. Further, the average of the threshold voltages was 6.2 V, and the standard deviation σ of the threshold voltages was 0.19.

  From the above, it was confirmed that very small variation characteristics were exhibited.

Example 7
(Formation of gate insulating film)
2.7 g of diparaxylylene (trade name: dix-N)) (manufactured by Daisan Kasei Co., Ltd.) is vacuum-deposited on a plastic substrate with a gate electrode on a plastic substrate with a gate electrode using a laboratory coater (manufactured by Parylene Japan, PDS2010). A bottom gate-bottom contact type organic thin film transistor was fabricated in the same manner as in Example 1 except that (paraxylylene) was used as the gate insulating film.
(Calculation of interface energy)
The interfacial energy calculated from the contact angle of water and diiodomethane to 2,7-di (n-hexyl) dithienobenzodithiophene, and the contact angle of water and diiodomethane to poly (paraxylylene) was 1.5 mJ. / M ² .
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, since the average carrier mobility of the fabricated 100 elements is 0.75 cm ² / Vs and the standard deviation σ of the carrier mobility is 0.072, the coefficient of variation CV (carrier mobility) is 9%. there were. In addition, since the average of the common logarithm of the current on / off ratio of 100 elements is 6.8 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.53, the coefficient of variation CV (log10AR) is It was 8%. The average threshold voltage was −0.052 V, and the standard deviation σ of the threshold voltage was 0.18.

  From the above, it was confirmed that very small variation characteristics were exhibited.

Comparative Example 1
(Formation of organic semiconductor layer and production of organic thin film transistor)
When forming the organic semiconductor layer, a bottom gate-bottom contact type was used in the same manner as in Example 1 except that a 0.2 wt% toluene solution was used and a drop cast method (0.5 μL was dropped) was used. An organic thin film transistor was produced.
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, since the average carrier mobility of the fabricated 100 elements is 0.37 cm ² / Vs and the standard deviation σ of the carrier mobility is 0.13, the coefficient of variation CV (carrier mobility) is 35%. there were. In addition, since the average of the common logarithm of the current on / off ratio of 100 elements is 7.3 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.48, the coefficient of variation CV (log10AR) is 7%. The average threshold voltage was −0.21 V, and the standard deviation σ of the threshold voltage was 0.29.

  FIG. 6 shows the 100-element transfer characteristic diagram, FIG. 7 shows the 100-element mobility histogram, and FIG. 8 shows the 100-element threshold voltage histogram.

  Since an organic thin film transistor was produced using a drop casting method that is not a printing process, an organic thin film transistor with small variation characteristics could not be obtained.

Comparative Example 2
(Formation of organic semiconductor layer and production of organic thin film transistor)
The same as Example 1 except that 2,8-difluoro-5,11-bis (triethylsilylethynyl) anthradithiophene (manufactured by Sigma-Aldrich) was used for the organic semiconductor (solute) and mesitylene was used for the solvent. A bottom gate-bottom contact type organic thin film transistor was prepared by the method.
(Calculation of interface energy)
Calculated from the contact angle of water and diiodomethane with 2,8-difluoro-5,11-bis (triethylsilylethynyl) anthradithiophene, and the contact angle of water and diiodomethane with poly (chloroparaxylylene) Interface energy was 0.79 mJ / m ² .
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, since the average carrier mobility of the fabricated 100 elements is 0.10 cm ² / Vs and the standard deviation σ of the carrier mobility is 0.030, the coefficient of variation CV (carrier mobility) is 30%. there were. In addition, since the average of the common logarithm of the current on / off ratio of 100 elements is 7.0 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.76, the coefficient of variation CV (log10AR) is 11%. The average threshold voltage was 0.85 V, and the standard deviation σ of the threshold voltage was 0.35.

  FIG. 9 shows the 100-element transfer characteristic diagram, FIG. 10 shows the 100-element mobility histogram, and FIG. 11 shows the 100-element threshold voltage histogram.

  Since the organic semiconductor film does not contain the organic semiconductor represented by the general formula (1), an organic thin film transistor having small variation characteristics cannot be obtained.

Comparative Example 3
(Formation of organic semiconductor layer and production of organic thin film transistor)
2,8-difluoro-5,11-bis (triethylsilylethynyl) anthradithiophene (manufactured by Sigma Aldrich) is used as the organic semiconductor (solute), and the solvent is mesitylene to form a 0.2 wt% solution, and the organic semiconductor layer The bottom gate-bottom contact type organic thin film transistor was formed in the same manner as in Example 1 except that the 0.2 wt% mesitylene solution was used and the drop cast method (0.5 μL was dropped) was used. Was made.
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, the average carrier mobility of the fabricated 100 elements is 0.10 cm ² / Vs, and the standard deviation σ of the carrier mobility is 0.060, so the coefficient of variation CV (carrier mobility) is 60%. there were. Further, since the average of the common logarithm of the current on / off ratio of 100 elements is 3.8 and the standard deviation σ of the common logarithm of the current on / off ratio is 1.5, the coefficient of variation CV (log10AR) is 39%. The average threshold voltage was 0.22 V, and the standard deviation σ of the threshold voltage was 0.68.

  FIG. 12 shows the 100-element transfer characteristic diagram, FIG. 13 shows the 100-element mobility histogram, and FIG. 14 shows the 100-element threshold voltage histogram.

  Since the organic semiconductor film does not contain the organic semiconductor represented by the general formula (1) and the organic thin film transistor is manufactured using a drop casting method that is not a printing process, an organic thin film transistor with small variation characteristics cannot be obtained. It was.

Comparative Example 4
(Formation of gate insulating film)
In a glove box, 1.0 g of polyvinylphenol (manufactured by Sigma-Aldrich, Mw-25000) and 4.0 g of propylene glycol 1-monomethyl ether 2-acetate (manufactured by Kanto Chemical Co., Ltd., deer special grade) are added to a 10 mL sample tube. 1 g of the solution obtained by stirring for a period of time, 0.5 g of poly (melamine-co-formaldehyde) (manufactured by Sigma-Aldrich, Mn˜432) and propylene glycol 1-monomethyl ether in a 10 mL sample tube in the glove box Spin coater (manufactured by Mikasa Co., Ltd.) using 0.5 ml of the solution obtained by mixing 2 g of the solution obtained by adding 4.5 g of 2-acetate (Kanto Chemical Co., Ltd., deer special grade) and stirring for 10 hours. MS-A100M), spin coat film formation on a plastic substrate with a gate electrode ( 00 rpm / 5 seconds, and 1500 rpm / 30 seconds), and a crosslinked polyvinylphenol having a thickness of 535 nm obtained by heat treatment at 90 ° C. × 10 minutes and 150 ° C. × 60 minutes was used as the gate insulating film. A bottom-gate / bottom-contact type organic thin film transistor was prepared in the same manner as described above.
(Calculation of interface energy)
The interfacial energy calculated from the contact angle of water and diiodomethane with 2,7-di (n-hexyl) dithienobenzodithiophene, and the contact angle of water and diiodomethane with crosslinked polyvinylphenol was 3.9 mJ / It was m ^2.
(Measurement of semiconductor and electrical properties)
An organic thin film transistor array was prepared in the same manner as in Example 2, and the electrical properties of the organic thin film transistor array were measured. Then, the carrier mobility and the current on / off ratio variation degree of the 100 organic thin film transistors were calculated with the coefficient of variation CV, and the threshold voltage variation degree was calculated with the standard deviation σ. As a result, since the average carrier mobility of the fabricated 100 elements is 0.32 cm ² / Vs and the standard deviation σ of the carrier mobility is 0.037, the coefficient of variation CV (carrier mobility) is 11%. there were. Further, since the average of the common logarithm of the current on / off ratio of 100 elements is 4.2 and the standard deviation σ of the common logarithm of the current on / off ratio is 0.87, the coefficient of variation CV (log10AR) is 21%. The average threshold voltage was −2.7 V, and the standard deviation σ of the threshold voltage was 0.67.

Since the interface energy between the material used for the gate insulating film and the organic semiconductor is larger than ² mJ / m ^2, an organic thin film transistor with small variation characteristics cannot be obtained.

  The organic thin film transistor of the present invention utilizes various characteristics such as a semiconductor pH sensor, a semiconductor ion sensor, a semiconductor pressure sensor, a semiconductor temperature sensor, and an optical sensor by taking advantage of high carrier mobility and small performance variations such as threshold voltage. Can be used.

(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 (9)

An organic thin film transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film, wherein the organic semiconductor film has the general formula (1)

[Wherein, R ^{1 to} R ⁶ are each independently a hydrogen atom, 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 1 to 1 carbon atoms. 20 alkoxy groups, C1-C20 alkylthio groups, C1-C20 haloalkyl groups, C3-C10 cycloalkyl groups, C6-C14 aryl groups, and 3- to 12-membered cyclohetero heterocycles An alkyl group, a 5- to 14-membered heteroaryl group, or general formula (2)

(In the formula, R ⁷ represents a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, a cycloheteroalkyl group having 3 to 12 members, or a heteroaryl group having 5 to 14 members. Y represents a divalent alkyl group having 1 to 6 carbon atoms or a divalent haloalkyl group having 1 to 6 carbon atoms.)
The group represented by these is shown. ]
The interface energy between a material used for the gate insulating film and the organic semiconductor is 2.0 mJ / m ² or less, and the organic semiconductor film is formed by a printing process. An organic thin film transistor characterized by being obtained. The organic thin-film transistor of Claim 1 whose material used for a gate insulating film is an organic coating type material. An organic thin film transistor having a gate electrode, a gate insulating film, a source electrode, a drain electrode, and an organic semiconductor film, wherein the organic semiconductor film has the general formula (1)

[Wherein, R ^{1 to} R ⁶ are each independently a hydrogen atom, 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 1 to 1 carbon atoms. 20 alkoxy groups, C1-C20 alkylthio groups, C1-C20 haloalkyl groups, C3-C10 cycloalkyl groups, C6-C14 aryl groups, and 3- to 12-membered cyclohetero heterocycles An alkyl group, a 5- to 14-membered heteroaryl group, or general formula (2)

(In the formula, R ⁷ represents a cycloalkyl group having 3 to 10 carbon atoms, an aryl group having 6 to 14 carbon atoms, a cycloheteroalkyl group having 3 to 12 members, or a heteroaryl group having 5 to 14 members. Y represents a divalent alkyl group having 1 to 6 carbon atoms or a divalent haloalkyl group having 1 to 6 carbon atoms.)
The group represented by these is shown. ]
An organic thin film transistor characterized in that the material used for the gate insulating film is poly (chloroparaxylylene), and the organic semiconductor film is formed by a printing process . The organic thin-film transistor of Claim 1 whose material used for a gate insulating film is poly (paraxylylene) and poly (dichloroparaxylylene). Organic semiconductor is represented by the general formula (3)

^(Wherein, R 1, ^{R 2} are each independently a hydrogen atom, an alkyl group, or an alkoxy group having 1 to 20 carbon atoms having 1 to 20 carbon atoms.)
The organic thin-film transistor in any one of Claims 1-4 represented by these. The organic process according to any one of claims 1 to 5, wherein the printing process for forming the organic semiconductor film is dispenser printing, inkjet printing, offset printing, relief printing, intaglio printing, gravure printing, slit coat printing, or screen printing. Thin film transistor. The organic thin-film transistor array obtained using the organic thin-film transistor in any one of Claims 1-6. The differential amplifier circuit obtained using the organic thin-film transistor in any one of Claims 1-6. An organic electronic device obtained using the differential amplifier circuit according to claim 8.

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