JP2003347624A - Method of refining organic semiconductor material, organic semiconductor material obtained by this refining method, and semiconductor device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To disclose a method of refining an organic semiconductor material which is suitable for mass productivity and capable of providing a high-purity material, and to provide the organic semiconductor material obtained by using this refining method and a semiconductor device using the same. <P>SOLUTION: The method of refining an organic semiconductor material is characterized in (1) that impurities are removed by a supercritical solvent, and (2) that the organic semiconductor material is a π-conjugated high-molecular component or (3) that the organic semiconductor material is selected from among a substitution product of a thiophene, vinylene, thienylene vinylene, phenylene vinylene, p-phenylene; a condensed polycyclic aromatic compound such as an olygomer in which the number n of repeating unit of these materials is 4-10 or a polymer or pentacene in which the number n of repeating unit is not less than 20, where two or more kinds of these materials are used as a repeating unit; and fullerenes. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying an organic semiconductor material, an organic semiconductor material obtained by the method, and a semiconductor device using the same. The present invention relates to a method for refining an organic semiconductor material capable of providing the above, an organic semiconductor material obtained using the refining method, and a semiconductor element using the same.

[0002]

2. Description of the Related Art Organic materials have been studied for use as active semiconductor layers in thin film field effect transistors (FETs). Organic materials are easy to process and are generally thin film F
Use as an active semiconductor layer in thin film devices is attractive because of its high affinity for the plastic substrate on which the ET is formed. These advantages are important when manufacturing large area devices at low cost. Organic semiconductor is thin film FE
To be used as an active semiconductor layer in T, the on / off ratio of the resulting device must be acceptable. Generally, on / off of thin film FET
The off ratio must be at least ^10-3 . As used herein, the term on / off ratio refers to the ratio of the source-drain current when the transistor is on to the source-drain current when the transistor is off.

The properties of an organic semiconductor material that indicate whether it is suitable for use as an active semiconductor layer are carrier mobility and (electrical) conductivity. Carrier mobility (μ) is a measure of the average drift velocity of particles (eg, electrons, holes) in a layer of semiconductor material;
It is important to determine how strongly the motion of such particles is affected by the applied electric field.

[0004] Conventional organic semiconductor materials often have large leakage currents and do not exhibit ideal transistor characteristics.
In addition, even if the transistor characteristics are exhibited, the on-off ratio is often small and is not practically used.

Although these excessive leakage currents and small carrier mobilities may be caused by device failure,
When using an organic semiconductor material, impurities in the organic semiconductor,
For example, trace metals that are catalyst residues used during synthesis,
In addition, impurities at the time of synthesis often act as carrier carriers or cause carrier scattering, resulting in an increase in leak current and a decrease in carrier mobility in many cases.

In order to improve the characteristics of these organic semiconductor materials, the leakage current, the carrier mobility, and the on-off ratio when the device is used, it is important to minimize impurities in the organic semiconductor itself.

[0007] Purification methods of these compounds include sublimation purification, column chromatography, and coprecipitation (Japanese Patent Laid-Open No.
0-190001) and the like, but do not indicate a leak current value, a carrier mobility, and an on-off ratio in a device using the organic semiconductor material that are satisfied by any of the methods. Was.

[0008]

The problem to be solved by the present invention is, first, to show a method for providing a large amount of high-purity organic semiconductor material. It is another object of the present invention to provide an organic semiconductor material purified using this purification method, and to provide an organic semiconductor device using the organic semiconductor material purified using the purification method.

[0009]

The object of the present invention is attained by the following. 1. A method for purifying an organic semiconductor material, comprising removing impurities using a solvent in a supercritical state.

[0010] 2. 2. The method for purifying an organic semiconductor material according to the above item 1, wherein the organic semiconductor material is a π-conjugated polymer compound.

3. The organic semiconductor material is thiophene, vinylene, chenylene vinylene, phenylene vinylene, p-
Phenylene, a substituted product thereof or an oligomer having two or more thereof as a repeating unit and having a repeating unit number n of 4 to 10; a polymer having a repeating unit number n of 20 or more; Wherein said 1 is selected from a ring aromatic compound and a fullerene
Or the method for purifying an organic semiconductor material according to 2.

4. 4. The method for purifying an organic semiconductor material according to claim 1, wherein the amount of impurities after the purification is 50 ppm or less and 0.01 ppm or more.

5. Among the impurities contained in the organic semiconductor material after the purification, the content of the periodic table 1, the group 2 element, the group 6 to 13 element and the halogen element is 20 ppm or less and 0.01 p.
pm or more, the method for purifying an organic semiconductor material according to any one of the above items 1 to 4,

6. Among the impurities contained in the purified organic semiconductor material, alkali metals, alkaline earth metals, Fe, N
At least one of i and Zn has a content of 10 ppm
The method for purifying an organic semiconductor material according to any one of the above 1 to 5, wherein the content is 0.01 ppm or more.

[0015] 7. 7. The method for purifying an organic semiconductor material according to any one of 1 to 6, wherein the organic semiconductor material is injected into a solvent in a supercritical state, and impurities are removed by using a chromatography method.

8. 7. The method for purifying an organic semiconductor according to any one of the above items 1 to 6, wherein the organic semiconductor material is extracted in a solvent in a supercritical state.

9. 7. The method for purifying an organic semiconductor according to any one of the above items 1 to 6, wherein the organic semiconductor material is crystallized in a solvent in a supercritical state.

10. 10. An organic semiconductor material purified by the purification method according to any one of 1 to 9 above.

11. The gap between the electrode films is connected by an organic semiconductor formed from the organic semiconductor material according to claim 10,
An organic transistor element comprising a source electrode and a drain electrode connected by a channel made of the organic semiconductor.

[12] 12. The organic transistor element according to the above item 11, having an insulating layer made of any one of silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, and titanium oxide. 13. The insulating layer is configured to discharge a mixture of at least one or more inert gases, at least one or more organometallic compounds, and at least one or more reactive gases to the discharge space under atmospheric pressure or a pressure close to atmospheric pressure. 13. The organic transistor element according to the above item 11 or 12, wherein the organic transistor element is formed on the substrate by being introduced into a plasma state and exposing the substrate to the mixed gas in the plasma state.

14. The organic transistor element according to any one of items 11 to 13, wherein the channel made of the organic semiconductor is formed in contact with an insulating layer made of any one of polyimide, polyamide, polyester, and polyacrylate.

15. 15. The organic transistor element according to any one of 11 to 14, wherein the substrate is a polymer support.

16. A method for manufacturing an organic transistor element, comprising a step of connecting an electrode film gap with the organic semiconductor material according to claim 10.

17. A display device using the organic transistor element according to any one of 11 to 16.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The organic semiconductor in the present invention is a substance composed of a certain amount of carbon or a carbon isotope in combination with another element,
At least 10 ⁻³ cm ² / V · cm at room temperature (20 ° C.)
FIG. The conductivity is 1 S / cm or less at 20 ° C. (JP-A-8-22803).
5).

The organic semiconductor material in the present invention is not particularly limited as long as it satisfies the above conditions. Preferably, a π-conjugated material (π-conjugated polymer compound) is used. Specifically, polypyrroles such as polypyrrole, poly (N-substituted pyrrole), poly (3-substituted pyrrole), poly (3,4-disubstituted pyrrole), polythiophene, poly (3-substituted thiophene), poly (3 , 4-disubstituted thiophene), polythiophenes such as polybenzothiophene, polyisothianaphthenes such as polyisothianaphthene, polyphenylenevinylenes such as polyphenylenevinylene, poly (p
Polyaniline, such as poly (p-phenylenevinylene), polyaniline, poly (N-substituted aniline), poly (3-substituted aniline), poly (2,3-substituted aniline), polyacetylene, etc. Polyacetylenes, polydiacetylenes such as polydiacetylene, polyazulene such as polyazulene, polypyrenes such as polypyrene, polycarbazoles, polycarbazoles such as poly (N-substituted carbazole),
Polyselenophenes such as polyselenophene, polyfurans such as polyfuran and polybenzofuran, poly (p-
Poly (p-phenylene) s such as phenylene), polyindoles such as polyindole, polypyridazines such as polypyridazine, naphthacene, pentacene, hexacene, heptacene, dibenzopentacene, tetrabenzopentacene, pyrene, dibenzopyrene, chrysene, Perylene, coronene, terylene, ovalene, quaterylene,
Polyacenes such as circum anthracene and derivatives in which a part of carbon of polyacenes is substituted with an atom such as N, S, O, or a functional group such as a carbonyl group (triphenodioxazine, triphenodithiazine, hexacene-6,15
-Quinone), polymers such as polyvinylcarbazole, polyphenylene sulfide, and polyvinylene sulfide, and polycyclic condensates described in JP-A-11-195790.

Further, α-sexithiophene α, ω-dihexyl-α-sexithiophene which is a thiophene hexamer having the same repeating unit as these polymers,
α, ω-dihexyl-α-quinkethiophene, α, ω-
Oligomers such as bis (3-butoxypropyl) -α-sexithiophene and styrylbenzene derivatives can also be suitably used. Further, metal phthalocyanines such as copper phthalocyanine and fluorine-substituted copper phthalocyanine described in JP-A-11-251601, naphthalene 1,4,
5,8-tetracarboxylic diimide, N, N'-bis (4-trifluoromethylbenzyl) naphthalene1,
Together with 4,5,8-tetracarboxylic diimide, N,
N'-bis (1H, 1H-perfluorooctyl),
N, N′-bis (1H, 1H-perfluorobutyl) and N, N′-dioctylnaphthalene 1,4,5,8-tetracarboxylic acid diimide derivative, naphthalene 2,3
Naphthalenetetracarboxylic diimides such as 6,7 tetracarboxylic diimide and anthracene 2,3
Condensed ring tetracarboxylic diimides such as anthracenetetracarboxylic diimides such as 6,7-tetracarboxylic diimide; C60, C70, C76, C78, C
Fullerenes such as 84, carbon nanotubes such as SWNT, and dyes such as merocyanine dyes and hemicyanine dyes.

Among these π-conjugated materials, thiophene, vinylene, chenylenevinylene, phenylenevinylene, p-phenylene represented by the following general formulas 1 to 6:
An oligomer having these substituents or two or more thereof as a repeating unit, and the number n of the repeating units is 4 to 10, a polymer having the number n of the repeating units of 20 or more, or a condensed polycyclic ring such as pentacene Aromatic compounds,
At least one selected from the group consisting of fullerenes, condensed ring tetracarboxylic diimides, and metal phthalocyanines
Species are preferred.

Other organic semiconductor materials include:
Tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTF) -perchloric acid complex, BEDTT
Organic molecular complexes such as a TF-iodine complex and a TCNQ-iodine complex can also be used. Further, σ-conjugated polymers such as polysilane and polygermane,
Organic / inorganic hybrid materials described in No. 60999 can also be mentioned.

[0030]

Embedded image

In the formula, X represents S, Se, Te, NH,
R1 to R4 represent H, an alkyl group, an aryl group, or a halogen atom, and N represents a positive integer.

In the present invention, the impurity is an element other than the elements constituting the organic semiconductor material, for example, copper phthalocyanine if it is a kind of metal phthalocyanine.
In this case, it indicates an element other than copper. In the case of an oligomer or a polymer containing thiophene as a repeating unit, a metal element, for example, zinc or nickel which is a catalyst for a continuous coupling reaction during synthesis corresponds to an impurity. Oligomers having a repeating unit of 3 or less and by-products also correspond to impurities.

In the present invention, these organic semiconductor materials are purified in a solvent in a supercritical state. By purifying in a solvent in a supercritical state, it is possible to surprisingly provide an organic semiconductor material exhibiting excellent characteristics not found in other purification methods.

The supercritical state in the present invention means a state in which the temperature exceeds the critical temperature and the critical pressure. For example, in the case of carbon dioxide, the critical temperature is 31 ° C. and the critical pressure is 7.3.
8 MPa. Above this range, the fluid has a large diffusion coefficient and a low viscosity, and the mass transfer and the concentration equilibrium are quickly reached, and the density is high like a liquid, so that efficient separation is possible. Moreover, the use of a substance that becomes a gas at normal pressure and normal temperature, such as carbon dioxide, makes the recovery quicker.

As the solvent in the supercritical state, carbon dioxide, nitrous oxide, ammonia, water, methanol, ethanol, 2-propanol, ethane, propane, butane, hexane, pentane and the like are preferably used.
Among them, carbon dioxide can be particularly preferably used. One type of supercritical solvent can be used alone, or a substance called a modifier or an entrainer for adjusting the polarity can be added.

As a purification method using a solvent in a supercritical state, chromatography, extraction, and crystallization using a packed column, an open column, or a capillary column can be preferably used. As the filler, silica used in a conventional chromatographic method, silica with a surface modified, or the like can be appropriately selected.

When the extraction is used, a method of passing a supercritical solvent through an extraction tube filled with a substance to be purified as shown in FIG. 1 can be preferably used.

In FIG. 1, a pump 1 is filled with a substance (gas) used for supercritical fluid purification, and a valve 2 is opened to fill a supercritical fluid compressed to a high pressure into an extraction pipe 3. A substance to be purified and, if necessary, an entrainer are placed in the extraction tube in advance. After performing the extraction step at a desired temperature for a predetermined time, the valve 4 is opened to release the pressure, and then the object to be purified is taken out. 5 is a sampling bottle.

As the crystallization, a method of changing the pressure and temperature of the supercritical solvent can be preferably mentioned.

The organic semiconductor material purified by the above method has a content of 10 ppm or less of the periodic table 1, group 2, element 6 to 13 and halogen element among the impurities contained in the purified organic semiconductor material. Is preferred. More preferably, the content of at least one impurity among alkali metals, alkaline earth metals, iron, nickel and zinc is preferably 5 ppm or less.

The amount of impurities can be measured by inductively coupled plasma-emission spectroscopy, mass spectrometry, X-ray fluorescence spectroscopy, or ion chromatography.

The amount of organic impurities and oligomers can be determined by gas chromatography / mass spectrometry, liquid chromatography / mass spectrometry, gel permeation chromatography, or the like.

According to an eleventh aspect of the present invention, the gap between the electrode films is connected by an organic semiconductor formed of the organic semiconductor material according to the tenth aspect, and the source electrode and the drain are connected by a channel made of the organic semiconductor. This is an organic transistor element having electrodes. As the configuration of such an organic transistor element, a known element can be used without any particular limitation.

According to a twelfth aspect of the present invention, there is provided the organic transistor device according to the eleventh aspect, further comprising an insulating layer made of any one of silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, and titanium oxide.

According to a thirteenth aspect of the present invention, the insulating layer comprises:
Atmospheric pressure or a pressure near the atmospheric pressure, a mixed gas comprising at least one or more inert gas, at least one or more organometallic compound and at least one or more reactive gas is introduced into a discharge space to form a plasma. 13. The substrate is formed on the base material by exposing the base material to the mixed gas in the plasma state.
The organic transistor element according to the above. As the plasma method, a known method can be used without any particular limitation.

According to a fourteenth aspect of the present invention, the channel made of the organic semiconductor is formed in contact with an insulating layer made of any one of polyimide, polyamide, polyester and polyacrylate. 3. The organic transistor element according to item 1.

The invention according to claim 15 is the organic transistor element according to any one of claims 11 to 14, wherein the base material is a polymer support. Known polymer supports can be used without particular limitation.

According to a sixteenth aspect of the present invention, in the method of manufacturing an organic transistor element, the gap between the electrode films is set to one.
A method for manufacturing an organic transistor element through a step of connecting with an organic semiconductor material described in Item 0.

Hereinafter, the present invention will be described in more detail. In one embodiment of the invention, the TFT is a metal-insulator-semiconductor field effect transistor (MIS-FET) having an active layer of an organic semiconductor material. The TFT is formed on a conventional substrate material such as glass, silicon, or plastic. The layer of insulating material is formed on the substrate using various techniques such as spin coating, cast molding or screen printing. The term insulating material means
A material having a conductivity of about 10 ⁻¹² S / cm or less. The active layer is formed on the insulating layer.

In general, a device has three spaced contacts. At least two of these contacts are in physical contact with the organic semiconductor layer and have a current path through at least a portion of such semiconductor layer. The third contact is in physical contact with the substrate and controls the current through the semiconductor layer located between the first and second contacts. The contacts are made of metal. Metals used as contacts in MIS-FET devices are conventional and well known to those skilled in the art.
One example of a suitable metal is gold.

In the present invention, a material having a functional group such as acrylic acid, acetamide, dimethylamino group, cyano group, carboxyl group, nitro group or the like, a benzoquinone derivative, tetracyanoethylene and tetracyanoquino in the organic semiconductor layer. Materials serving as acceptors that accept electrons, such as dimethane and derivatives thereof, and materials having functional groups such as amino group, triphenyl group, alkyl group, hydroxyl group, alkoxy group, and phenyl group, and phenylenediamine Materials such as substituted amines, anthracene, benzoanthracene, substituted benzoanthracenes, pyrene, substituted pyrene, carbazole and derivatives thereof, and tetrathiafulvalene and derivatives thereof, which are materials that can serve as donors of electrons are contained ( So-called doping).

Examples of the method for producing these organic thin films include a vacuum deposition method, a molecular beam epitaxial growth method, an ion cluster beam method, a low energy ion beam method, an ion plating method, a CVD method, a sputtering method, a plasma polymerization method, and an electrolytic polymerization method. , A chemical polymerization method, a spin coating method, a casting method, a dipping method, a roll coating method, a bar coating method, an LB method and the like, which can be adopted according to the material. Among them, in terms of productivity, the spin coating method, which is easy to form a thin film,
Casting, dipping, roll coating, and bar coating are preferred.

The thickness of the thin film made of the organic semiconductor is not particularly limited, but the characteristics of the obtained transistor are often largely influenced by the thickness of the active layer made of the organic semiconductor. Although it depends on the organic semiconductor, it is generally preferably 1 μm or less, particularly preferably 300 nm or less. The electrical properties of an organic thin film that effectively works as an active layer by performing a chemical treatment after the formation of the thin film are often controlled by doping treatment. However, as long as other element components are not chemically altered, (1) Phase doping, (2) doping from liquid phase, (3) electrochemical doping, (4) chemical doping such as photoinitiated doping and the publication "Industrial Materials, Vol. 34, No. 4, 55"
1986, pp. 1986, can be used.

As a method for applying the composition of each layer, known coating methods such as dipping, spin coating, knife coating, bar coating, blade coating, squeezing coating, reverse roll coating, gravure roll coating, curtain coating, spray coating, die coating, etc. A coating method capable of continuous coating or thin film coating can be preferably used.

The device configuration of the present invention will be described with reference to FIG. For the source electrode 12, the drain electrode 13 and the gate electrode 15, use a metal material such as Au, Ag, Al, Cu, Pt, and Cr, a transparent conductive film such as ITO, SnO ₂ , and ZnO, or a known conductive polymer. Can be. In order to obtain good characteristics, it is preferable to use a metal, an alloy, an electrically conductive compound, or a mixture thereof having a large work function (4.5 eV or more) as an electrode material.

The gate electrode, source electrode, and drain electrode are not particularly limited as long as they are conductive materials.
Gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium, palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin / antimony oxide, indium / tin oxide (ITO ), Fluorine-doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste and carbon paste, lithium,
Beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloy, magnesium, lithium, aluminum,
A magnesium / copper mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide mixture, a lithium / aluminum mixture, etc. are used.
In particular, platinum, gold, silver, copper, aluminum, indium,
ITO and carbon are preferred. Alternatively, a known conductive polymer whose conductivity has been improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylene dioxythiophene and polystyrene sulfonic acid, or the like is also preferably used. As the source electrode and the drain electrode, those having low electric resistance at the contact surface with the semiconductor layer are preferable among the above.

As a method of forming an electrode, a method of forming an electrode using a known photolithographic method or a lift-off method on a conductive thin film formed by using the above materials as a raw material by vapor deposition, sputtering, or the like, aluminum, copper, etc. And etching using a resist by thermal transfer, ink jet or the like on the metal foil. A conductive polymer solution or dispersion or a conductive fine particle dispersion may be directly patterned by ink jet, or may be formed from a coating film by lithography or laser ablation. Further, a method of patterning an ink, a conductive paste, or the like containing a conductive polymer or conductive fine particles by a printing method such as letterpress, intaglio, lithographic, or screen printing can also be used.

Also in the case of a sheet-shaped organic semiconductor device, the material and forming method of the signal lines, scanning lines, and display electrodes can be formed in the same manner as described above. .

Various insulating films may be used as the insulating layer 16.
However, an inorganic oxide film is particularly preferable. Toriwa
Ke SiO₂, SiN, Al₂O₃, Ta₂O₅, TiO
₂Is preferred. Polyimid is another preferred insulating film.
What is polyamide, polyester, polyacrylate?
And a layer composed of the same. SiO₂, SiN, Al
₂O₃, Ta₂O₅And TiO₂Is an organic semiconductor channel
To increase the carrier density of polyimide and poly
Mid, polyester and polyacrylate rubbing
After performing orientation treatment such as
In terms of increasing the electric field mobility of carriers due to
Either one is preferred.

In addition, a photo-curable resin of a photo-radical polymerization type or a photo-cationic polymerization type, a copolymer containing an acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, a novolak resin, cyanoethyl pullulan, and the like can also be used. For example, SiO ₂ , SiN, A
When an insulating layer is formed of an inorganic oxide such as l ₂ O ₃ , Ta ₂ O ₅ , and TiO ₂ , it is effective to form a film by plasma treatment under atmospheric pressure.

In the most preferred embodiment, the gate insulating film
Especially SiO₂, SiN, Al ₂O₃, Ta
₂O₅, TiO₂And the gate insulating film is an organic semiconductor
Polyimide, polyamide, poly
Made of either ester or polyacrylate, oriented
After processing, it is necessary to provide a layer on which the organic semiconductor film is provided.
Is preferred.

The plasma film forming process under the atmospheric pressure refers to a process of discharging under the atmospheric pressure or a pressure near the atmospheric pressure, exciting the reactive gas by plasma, and forming a thin film on the substrate. The method is described in JP-A-11-61406 and 11-1.
33205, JP-A-2000-121804, 2000
147209 and 2000-185362. Thereby, a highly functional thin film can be formed with high productivity.

SiO ₂ , SiN, Al ₂ O ₃ , Ta ₂ O
_{5. When} the insulating layer 16 is formed of TiO ₂ or the like, at least one selected from metal alkoxides and hydrolysates thereof and a composition containing an organic solvent are applied by dip coating or the like, and active energy rays such as heat rays are applied. Alternatively, it can be cured by applying energy such as ultraviolet rays. For example, JP-A-2000-327310 and JP-A-2000-3
44504 can be referred to.

Polyimide, polyamide, polyester,
The layer made of any one of the polyacrylates may be a film formed, or may be applied using a coating solution dissolved or dispersed in a solvent. As a coating method, known coating methods such as dipping, spin coating, knife coating, bar coating, blade coating, squeeze coating, reverse roll coating, gravure roll coating, curtain coating, spray coating, and die coating can be adopted. A coating method capable of coating a thin film is preferably used. Further, patterning may be performed by inkjet or screen printing.

In addition, the configurations shown in FIGS. 3 and 4 are also possible. 3 and 4, the same reference numerals as those in FIG. 2 indicate the same elements, and a description thereof will be omitted.

The inorganic oxide film and the organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm.
m to 1 μm.

As the support 17 (substrate), a polymer film (polymer support) is preferably used. For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PE)
S), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose acetate propionate (CAP), and the like.

To these polymer films, a plasticizer such as trioctyl phosphate or dibutyl phthalate may be added, or a known ultraviolet absorber such as benzotriazole or benzophenone may be added. Further, a resin prepared by applying a so-called organic-inorganic polymer hybrid method, in which a raw material of an inorganic polymer such as tetraethoxysilane is added, and a high molecular weight is obtained by applying energy such as a chemical catalyst or heat or light, is used. It can also be used as a raw material.

It is also possible to provide a transparent protective layer on the display element of the present invention, for example, to form a functional film such as an anti-reflection layer.

The invention described in claim 17 is directed to claim 11
A display device using the organic transistor element according to any one of Items 1 to 16.

The organic semiconductor device is a liquid crystal display element,
It can be suitably used for organic EL devices and digital paper represented by e-ink. Known digital papers can be used without any particular limitation.

[0072]

EXAMPLES The present invention will be described below in detail with reference to examples, but the embodiments of the present invention are not limited to these examples.

Example 1 Aldrich pentacene was purified under the following conditions using a supercritical fluid chromatography system manufactured by Jillson under the following conditions.

Column: C18-Silica, 3μ
m, 2 × 100 mm Moving bed: carbon dioxide moving bed Flow rate: 2 mL / min Pressure: 9 MPa Temperature: 80 ° C. Detection: UV detector (210 nm)

The above purification yielded 50 mg of pentacene. This pentacene is designated as 101 (Invention 1).

Separately, pentacene was purified by the usual sublimation purification method. This pentacene is designated as 102 (Comparative Example 1).

After a thermal oxide film (SiO ₂ ) having a thickness of 500 nm was formed on a p-type silicon substrate, 5 nm of chromium and 100 nm of gold were sequentially deposited thereon to form a film. A channel groove of 5 μm was formed in the electrode film by photolithography, and divided into a source electrode and a drain electrode.
Observing the SiO ₂ film at the gate part, it is about 50n from the surface
m had been removed.

Next, pentacene obtained by the above purification was deposited on the above channel.

Further, the wiring shown in FIG. 5 was additionally provided, and the transistor characteristics were evaluated. Leakage current Ioff when the applied voltage between the source electrode and the drain electrode is -30 V,
And the current value Ion when -30 V is applied to the gate electrode
The result of evaluating the on / off ratio Ion / Ioff with the following is as follows.

As Comparative Example 2, a transistor element was prepared in the same manner as in Example 1 except that purification was not performed, and the leakage current (pA) and the on / off ratio were evaluated.
That is, the applied voltage between the source electrode and the drain electrode is -30.
V and the on / off ratio I to the current value Ion when -30 V is applied to the gate electrode.
on / Ioff was evaluated. Table 1 shows the results.

[0081]

[Table 1]

Example 2 Poly (3-hexylthiophene) manufactured by Aldrich is shown in FIG.
Supercritical extraction was performed using the apparatus shown in (1).

Extraction solvent: carbon dioxide Temperature: 80 ° C Pressure: 10MPa Extraction tube capacity: 100ml Extraction time: 30 minutes

Under the above conditions, 500 mg of poly (3-hexylthiophene) was obtained. This is designated as 201 (present invention 2).

Separately, poly (3-hexylthiophene) was purified by a coprecipitation method described in JP-A-10-190001. This is designated as 202 (Comparative Example 3). Note that Comparative Example 4 was the same as Example 2 except that purification was not performed.

Before and after purification, the contained elements of poly (3-hexylthiophene) were quantified by ICP-MS. The measurement results are shown in Table 2 (unit: ppm).

[0087]

[Table 2]

Further, before and after purification, the poly (3-hexylthiophene) was dissolved in THF, and the molecular weight distribution was measured by GPC measurement. The distribution of mountains was shown.

Purified poly (3-hexylthiophene)
Was applied on a channel prepared in the same manner as in Example 1 by spin coating using chloroform as a solvent. Dry to remove chloroform, heat treat at 100 ° C. for 5 minutes and leave in vacuum for 24 hours. The thickness of the obtained poly (3-hexylthiophene) film was about 50 nm.

After exposure for 5 hours at room temperature in an ammonia gas atmosphere, the wiring shown in FIG. 5 was provided.

A device was prepared in the same manner as in Example 1 using poly (3-hexylthiophene) which had not been further purified. This is referred to as Comparative Example 5.

The transistor characteristics were evaluated. Leakage current Ioff when the applied voltage between the source electrode and the drain electrode is -30 V, and -30 V for the gate electrode
On / off ratio Ion / I with current value Ion when applied
Table 3 shows the results of evaluating the off.

Separately from this, an atmospheric pressure plate is placed on a silicon substrate.
500nm thick SiO by Zuma method ₂Substrate with film formed
Purified using the solvent in the supercritical state
Transistor element using (3-hexylthiophene)
It was created. This is designated as 301 (present invention 3). Operation
Table 3 summarizes the evaluation of the properties.

[0094]

[Table 3]

[0095]

According to the present invention, a high-purity organic semiconductor material can be provided in a large amount, and an organic semiconductor material purified using this purification method can be provided. And an organic semiconductor device using the organic semiconductor material purified.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus used in the purification method of the present invention, in which a white circle indicates a supercritical fluid and a black circle indicates an object to be purified.

FIG. 2 is a schematic explanatory view showing one embodiment of a semiconductor device using an organic semiconductor device obtained by a purification method according to the present invention.

FIG. 3 is a schematic explanatory view showing another example.

FIG. 4 is a schematic explanatory view showing another example.

FIG. 5 is a schematic diagram of a transistor characteristic evaluation system used in an example.

[Explanation of symbols]

1 pump 2 valves 3 Extraction tube 4 valves 5 Collection bin 11 Organic semiconductor 12 Source electrode 13 Drain electrode 14 channels 15 Gate electrode 16 Insulation layer 17 Support

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C07B 63/00 H01L 29/78 618A 617T 617V (72) Inventor Isao Kobayashi 1 Sakuracho, Hino City, Tokyo Address Konica Co., Ltd. (72) Inventor Saori Nishio Sakuracho, Hino City, Tokyo 1 Konica Co., Ltd. (72) Inventor Hiroyuki Yasukawa 1 Kino Co., Ltd., Hino City, Tokyo 1 Konica Co., Ltd. (72) Inventor Akira Maruyama 1 Konica Co., Ltd., Konica Corporation, Hino City, Tokyo (72) Inventor Yuji Nishikawa 1 Konica Co., Ltd., Konica Corporation, Hino City, Tokyo 4D056 AB06 AB07 AB08 AB20 AC24 BA16 CA34 CA39 4H006 AA02 AD15 BB11 BB14 BB30 BB31 BE14 BE40 BE41 4J031 CC05 5F110 AA16 CC03 CC05 CC07 DD01 DD02 DD05 DD13 EE01 EE02 EE03 EE04 EE06 EE07 EE41 EE42 EE43 EE44 FF01 FF02 FF03 FF21 FF27 FF30 GG05 GG06 GG24 GG41 GG42 GG43 GG44 HK01 HK02 HK03 HK04 HK06 HK07 HK21 HK31 HK32 HK33 QQ06

Claims (17)

[Claims] 1. A method for purifying an organic semiconductor material, comprising removing impurities using a solvent in a supercritical state. 2. The method for purifying an organic semiconductor material according to claim 1, wherein the organic semiconductor material is a π-conjugated polymer compound. 3. An organic semiconductor material comprising thiophene, vinylene, chenylene vinylene, phenylene vinylene, p-phenylene, a substituted product thereof or two or more thereof as a repeating unit, and the number n of the repeating unit is 4 to 4. 3. The organic semiconductor material according to claim 1, wherein the oligomer is 10 or a polymer in which the number n of the repeating units is 20 or more, a condensed polycyclic aromatic compound such as pentacene, or a fullerene. 4. Purification method. 4. The method according to claim 1, wherein the amount of impurities after purification is 50 ppm or less and 0.01 ppm or more.
4. The method for purifying an organic semiconductor material according to 2 or 3. 5. The impurities contained in the purified organic semiconductor material, wherein the content of elements of Group 1, 2 and 6 to 13 and the halogen element of the periodic table are 20 ppm or less and 0.01 ppm.
The method for purifying an organic semiconductor material according to claim 1, wherein: 6. Among impurities contained in the purified organic semiconductor material, alkali metals, alkaline earth metals, Fe, Ni,
The method for purifying an organic semiconductor material according to claim 1, wherein the content of at least one kind of Zn is 10 ppm or less and 0.01 ppm or more. 7. The purification of an organic semiconductor material according to claim 1, wherein the organic semiconductor material is injected into a solvent in a supercritical state, and impurities are removed by a chromatographic method. Method. 8. The method for purifying an organic semiconductor according to claim 1, wherein the organic semiconductor material is extracted in a solvent in a supercritical state. 9. The method for purifying an organic semiconductor according to claim 1, wherein the organic semiconductor material is crystallized in a solvent in a supercritical state. 10. An organic semiconductor material purified by the purification method according to claim 1. 11. A semiconductor device according to claim 10, wherein the gaps between the electrode films are connected by an organic semiconductor formed of the organic semiconductor material according to claim 10, and a source electrode and a drain electrode connected by a channel made of the organic semiconductor. Characteristic organic transistor element. 12. The organic transistor device according to claim 11, further comprising an insulating layer made of any one of silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, and titanium oxide. 13. The method according to claim 13, wherein the insulating layer comprises at least one kind of inert gas at atmospheric pressure or a pressure close to atmospheric pressure;
By introducing a mixed gas comprising at least one or more organometallic compounds and at least one or more reactive gases into a discharge space to form a plasma state, and exposing the base material to the mixed gas in the plasma state, The organic transistor element according to claim 11, wherein the organic transistor element is formed. 14. The channel according to claim 11, wherein the channel made of an organic semiconductor is formed in contact with an insulating layer made of any one of polyimide, polyamide, polyester and polyacrylate. Organic transistor element. 15. The organic transistor device according to claim 11, wherein the substrate is a polymer support. 16. A method for manufacturing an organic transistor element, comprising the step of connecting an electrode film gap with the organic semiconductor material according to claim 10. 17. A display device using the organic transistor element according to claim 11.