JP5103735B2 - Composition for organic semiconductor layer, method for producing thin film transistor, method for producing active matrix device, method for producing electro-optical device, and method for producing electronic apparatus - Google Patents

Description

  The present invention relates to a composition for an organic semiconductor layer, a method for manufacturing a thin film transistor, a method for manufacturing an active matrix device, a method for manufacturing an electro-optical device, and a method for manufacturing an electronic device.

In recent years, a thin film transistor using an organic semiconductor material has attracted attention as a device that can replace a thin film transistor using an inorganic semiconductor material (see, for example, Patent Document 1).
In this thin film transistor, the organic semiconductor layer can be formed by a liquid phase process that does not require high temperature and high vacuum, and has advantages such as being suitable for reduction in thickness and weight and flexibility.

By the way, in the liquid phase process, an organic semiconductor layer is formed by applying an ink containing an organic semiconductor material to a predetermined organic semiconductor layer formation region and performing post-processing.
Here, in order to uniformly apply the ink and suppress variations among the formed organic semiconductor layers, the properties of the ink are important.
For example, when the ink jet method is used as an ink application method, it is necessary to adjust the surface tension, viscosity, and boiling point of the ink to an appropriate range in order to apply the ink uniformly. Research has been done.

In addition, it is considered that the properties and composition of the ink also affect the thin film characteristics such as crystallinity of the organic semiconductor layer to be formed.
However, little consideration has been given to the relationship between the ink and the thin film characteristics of the organic semiconductor layer. For this reason, the conventional inks have a problem that it is not possible to form an organic semiconductor layer with sufficiently excellent thin film characteristics.

Japanese Patent Laid-Open No. 2004-6682

  It is an object of the present invention to produce a composition for an organic semiconductor layer capable of forming an organic semiconductor layer having a high molecular structure planarity and excellent thin film characteristics, and a highly reliable thin film transistor manufactured using the composition. Another object of the present invention is to provide a method for manufacturing a thin film transistor, a method for manufacturing an active matrix device, a method for manufacturing an electro-optical device, and a method for manufacturing an electronic apparatus.

Such an object is achieved by the present invention described below.
The composition for organic semiconductor layers of the present invention has an organic semiconductor material satisfying the following conditions I and II, and a second virial coefficient for the organic semiconductor material at 25 ° C. of −1 × 10 ⁻³ to 1 × 10 ⁻⁴ cm. ^The composition for organic-semiconductor layers characterized by including the solvent which is ³ * mol / g < ² >.
Condition I: The organic semiconductor material includes a main chain composed of a plurality of thiophene rings bonded in a straight chain, and a side chain branched from at least one position of the main chain and including a plurality of carbon atoms And have.
Condition II: When the organic semiconductor material is dissolved in a solvent whose second virial coefficient with respect to the organic semiconductor material at 25 ° C. is outside the range of −1 × 10 ⁻³ to 1 × 10 ⁻³ cm ³ · mol / g ^2. The side chains extend, the side chains interfere with each other, and the planarity of the main chain is impaired.
Thereby, the composition for organic semiconductor layers which can form the organic-semiconductor layer excellent in the planarity of a molecular structure and excellent in the thin film characteristic is obtained.
A thiophene ring is particularly excellent in carrier mobility between adjacent thiophene rings, and an organic semiconductor layer formed using an organic semiconductor material containing a thiophene ring in the main chain exhibits excellent carrier mobility. As a result, it is possible to form an organic semiconductor layer having better thin film characteristics and better semiconductor characteristics.

In the composition for organic semiconductor layers of the present invention, the total number of carbon atoms in the side chain is preferably 4-12.
Thereby, while maintaining the solubility with respect to the solvent of an organic-semiconductor material fully, the length of a side chain shall be made into the length of the grade which does not produce a three-dimensional structural obstacle (interference) especially between adjacent side chains. it can. As a result, the planarity of the three-dimensional structure of the main chain constituting the organic semiconductor material can be improved, and the carrier mobility of the organic semiconductor layer formed using this organic semiconductor material can be increased.
In the composition for an organic semiconductor layer of the present invention, the side chain is preferably an alkyl chain.
Since the alkyl chain is mainly composed of a nonpolar portion derived from a C—H bond, the solubility in a solvent can be particularly enhanced.

In the composition for an organic semiconductor layer of the present invention, the solvent is preferably anisole , dichloromethane, or trichloroethane.
Thereby, the conjugated length of the π-conjugated structure becomes longer, and an organic semiconductor layer exhibiting particularly excellent carrier mobility can be obtained.
In the composition for an organic semiconductor layer of the present invention, the weight average molecular weight of the organic semiconductor material is preferably 1000 to 1000000.
This makes it particularly easy to synthesize and handle organic semiconductor materials.
In the composition for organic semiconductor layers of the present invention, the content of the organic semiconductor material in the composition for organic semiconductor layers is preferably 0.1 to 5 wt%.
Thereby, an organic semiconductor layer having a sufficient thickness can be formed while reliably preventing the organic semiconductor material from being deposited.

A thin film transistor manufacturing method according to the present invention includes a source electrode, a drain electrode, a gate electrode, an organic semiconductor layer, and a gate insulating film that insulates the source electrode and the drain electrode from the gate electrode. A manufacturing method comprising:
An organic semiconductor material that satisfies the following conditions I and II, and a solvent having a second virial coefficient of −1 × 10 ⁻³ to 1 × 10 ⁻⁴ cm ³ · mol / g ² for the organic semiconductor material at 25 ° C. The organic semiconductor layer is formed by applying a composition for an organic semiconductor layer.
Condition I: The organic semiconductor material includes a main chain composed of a plurality of thiophene rings bonded in a straight chain, and a side chain branched from at least one position of the main chain and including a plurality of carbon atoms And have.
Condition II: When the organic semiconductor material is dissolved in a solvent whose second virial coefficient with respect to the organic semiconductor material at 25 ° C. is outside the range of −1 × 10 ⁻³ to 1 × 10 ⁻³ cm ³ · mol / g ^2. The side chains extend, the side chains interfere with each other, and the planarity of the main chain is impaired.
Thereby, a thin film transistor having excellent transistor characteristics and high reliability can be obtained.

The manufacturing method of the active matrix device of the present invention includes the manufacturing method of the thin film transistor of the present invention.
Thereby, an active matrix device with high reliability can be obtained.
The method for manufacturing an electro-optical device according to the present invention includes the method for manufacturing an active matrix device according to the present invention.
Thereby, a highly reliable electro-optical device is obtained.
According to another aspect of the invention, there is provided an electronic apparatus manufacturing method including the electro-optical device manufacturing method of the invention.
As a result, a highly reliable electronic device can be obtained.

Hereinafter, the composition for an organic semiconductor layer, the method for producing a thin film transistor, the method for producing an active matrix device, the method for producing an electro-optical device, and the method for producing an electronic device according to the present invention will be described in detail based on the preferred embodiments shown in the drawings. .
<First Embodiment>
First, 1st Embodiment of the thin-film transistor manufactured using the composition for organic-semiconductor layers of this invention is described.
FIG. 1 is a schematic diagram showing a first embodiment of a thin film transistor manufactured using the composition for an organic semiconductor layer of the present invention ((a) is a longitudinal sectional view, (b) is a plan view) in FIG. 2 is a diagram (longitudinal sectional view) for explaining a method of manufacturing the thin film transistor shown in FIG. 1, and FIG. 3 is a diagram (schematic diagram) for explaining a three-dimensional structure of poly (3-hexylthiophene). .

  A thin film transistor 1 illustrated in FIG. 1 is a bottom-gate thin film transistor, and is provided on a gate electrode 50, a gate insulating layer 40 provided so as to cover the gate electrode 50, and the gate insulating layer 40 separately from each other. The source electrode 20a and the drain electrode 20b, and the organic semiconductor layer 30 provided so as to cover the source electrode 20a and the drain electrode 20b are provided on the substrate 10.

Hereinafter, the configuration of each unit will be sequentially described.
The substrate 10 supports each layer (each part) constituting the thin film transistor 1.
The substrate 10 includes, for example, a plastic substrate (glass substrate, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), aromatic polyester (liquid crystal polymer), polyimide (PI), etc. Resin substrate), quartz substrate, silicon substrate, metal substrate, gallium arsenide substrate, and the like can be used.
In the case where flexibility is given to the thin film transistor 1, a plastic substrate or a thin (relatively small film thickness) metal substrate is selected as the substrate 10.

On the substrate 10, a gate electrode 50 for generating an electric field in an organic semiconductor layer 30 described later is provided.
The material of the gate electrode 50 is not particularly limited as long as it is a known electrode material. Specifically, metal materials such as Cr, Al, Ta, Mo, Nb, Cu, Ag, Au, Pd, In, Ni, Nd, Co or alloys containing these, and oxides thereof are used. Can do.
Moreover, the gate electrode 50 can also be comprised with a conductive organic material.
The average thickness of the gate electrode 50 is not particularly limited, but is preferably about 0.1 to 2000 nm, and more preferably about 1 to 1000 nm.

A gate insulating layer (insulator layer) 40 is provided on the gate electrode 50.
The gate insulating layer 40 insulates the gate electrode 50 from a source electrode 20a and a drain electrode 20b described later.
The constituent material of the gate insulating layer 40 is not particularly limited as long as it is a known gate insulator material, and either an organic material or an inorganic material can be used.

Examples of the organic material include polymethyl methacrylate, polyvinyl phenol, polyimide, polystyrene, polyvinyl alcohol, polyvinyl acetate, polyvinyl phenol, and the like, and one or more of these can be used in combination.
On the other hand, examples of the inorganic material include metal oxides such as silica, silicon nitride, aluminum oxide, and tantalum oxide, and metal composite oxides such as barium strontium titanate and lead zirconium titanate. A combination of more than one species can be used.

The average thickness of the gate insulating layer 40 is not particularly limited, but is preferably about 10 to 5000 nm, and more preferably about 100 to 2000 nm. By setting the thickness of the gate insulating layer 40 within the above range, the operating voltage of the thin film transistor 1 can be lowered while reliably insulating the source electrode 20a and the drain electrode 20b from the gate electrode 50.
Note that the gate insulating layer 40 is not limited to a single-layer structure, and may have a multilayer structure.

On the gate insulating layer 40, a source electrode 20a and a drain electrode 20b (a pair of electrodes) are provided. That is, the source electrode 20a and the drain electrode 20b are provided on substantially the same plane.
The constituent material of the source electrode 20a and the drain electrode 20b can be the same as the constituent material of the gate electrode 50.

When the organic semiconductor layer 30 is p-type, the constituent materials of the source electrode 20a and the drain electrode 20b are preferably mainly composed of Au, Ag, Cu, Pt, or an alloy containing these, respectively. Since these have a relatively large work function, the efficiency of injecting holes (carriers) into the organic semiconductor layer 30 can be improved by forming the source electrode 20a with these materials.
In addition, although the average thickness of the source electrode 20a and the drain electrode 20b is not specifically limited, It is preferable that it is about 10-2000 nm, respectively, and it is more preferable that it is about 50-1000 nm.

The distance between the source electrode 20a and the drain electrode 20b, that is, the channel length L shown in FIG. 1 is preferably about 2 to 30 μm, and more preferably about 2 to 20 μm. By setting the value of the channel length L in such a range, the characteristics of the thin film transistor 1 can be improved (in particular, the ON current value can be increased).
Further, the length of the source electrode 20a and the drain electrode 20b, that is, the channel width W shown in FIG. 1, is preferably about 0.1 to 5 mm, and more preferably about 0.3 to 3 mm. By setting the value of the channel width W in such a range, the parasitic capacitance can be reduced, and deterioration of the characteristics of the thin film transistor 1 can be prevented. In addition, an increase in size of the thin film transistor 1 can be prevented.

An organic semiconductor layer 30 is provided on the gate insulating layer 40 so as to be in contact with the source electrode 20a and the drain electrode 20b.
The constituent material of the organic semiconductor layer 30 will be described in the thin film transistor manufacturing method described later.
The average thickness of the organic semiconductor layer 30 is not particularly limited, but is preferably about 0.1 to 1000 nm, more preferably about 1 to 500 nm, and further preferably about 1 to 100 nm.

In such a thin film transistor 1, when a gate voltage is applied to the gate electrode 50 with a voltage applied between the source electrode 20a and the drain electrode 20b, a channel is formed near the interface between the organic semiconductor layer 30 and the gate insulating layer 40. As a result, carriers (holes) move through the channel region, whereby a current flows between the source electrode 20a and the drain electrode 20b.
That is, in the OFF state in which no voltage is applied to the gate electrode 50, even if a voltage is applied between the source electrode 20a and the drain electrode 20b, almost no carriers are present in the organic semiconductor layer 30; Only flows.
On the other hand, in the ON state in which a voltage is applied to the gate electrode 50, charges are induced in the portion of the organic semiconductor layer 30 facing the gate insulating layer 40, and a channel (carrier flow path) is formed. When a voltage is applied between the source electrode 20a and the drain electrode 20b in this state, a current flows through the channel region.

Next, the composition for an organic semiconductor layer of the present invention will be described by taking as an example the case of manufacturing the thin film transistor shown in FIG.
1 includes a step [A1] of forming the gate electrode 50 on the substrate 10, a step [A2] of forming the gate insulating layer 40 on the gate electrode 50, and the gate insulating layer 40. The step [A3] of forming the source electrode 20a and the drain electrode 20b, and the step [A4] of forming the organic semiconductor layer 30 so as to cover the source electrode 20a and the drain electrode 20b.

[A1] Gate Electrode Formation Step A gate electrode 50 is formed on the substrate 10 (see FIG. 2A).
First, a metal film (metal layer) is formed.
This includes, for example, chemical vapor deposition (CVD) such as plasma CVD, thermal CVD, laser CVD, vapor deposition, sputtering (low temperature sputtering), dry plating methods such as ion plating, electrolytic plating, immersion plating, electroless plating, etc. It can be formed by the wet plating method, thermal spraying method, sol-gel method, MOD method, metal foil bonding, and the like.

On this metal film, a resist material is applied and then cured to form a resist layer having a shape corresponding to the shape of the gate electrode 50. Using this resist layer as a mask, unnecessary portions of the metal film are removed.
For the removal of the metal film, for example, one or more of physical etching methods such as plasma etching, reactive ion etching, beam etching, and light assist etching, and chemical etching methods such as wet etching are used. They can be used in combination.

Then, the gate electrode 50 is obtained by removing the resist layer.
The gate electrode 50 is formed on the gate insulating layer 40 by, for example, applying (supplying) conductive particles or a conductive material containing a conductive organic material to form a coating film. It can also be formed by subjecting the coating film to post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.).

Examples of the conductive material containing conductive particles include a dispersion in which metal fine particles are dispersed, a polymer mixture containing conductive particles, and the like.
Moreover, as a conductive material containing a conductive organic material, a solution or dispersion of a conductive organic material can be given.
As a method for applying (supplying) the conductive material on the substrate 10, for example, a coating method such as a spin coating method or a dip coating method, a printing method such as an ink jet printing method (droplet discharge method) or a screen printing method. Etc.

[A2] Gate Insulating Layer Formation Step Next, the gate insulating layer 40 is formed on the gate electrode 50 (see FIG. 2B).
For example, when the gate insulating layer 40 is composed of an organic polymer material, the gate insulating layer 40 is applied (supplied) so as to cover the gate electrode 50 with a solution containing the organic polymer material or its precursor, If necessary, it can be formed by subjecting this coating film to post treatment (for example, heating, irradiation with infrared rays, application of ultrasonic waves, etc.).

As a method for applying (supplying) a solution containing an organic polymer material or a precursor thereof onto the gate electrode 50, the application method, the printing method, and the like mentioned in the above step [A1] can be used.
When the gate insulating layer 40 is made of an inorganic material, the gate insulating layer 40 can be formed by, for example, a thermal oxidation method, a CVD method, or an SOG method. Further, by using polysilazane as a raw material, a silica film and a silicon nitride film can be formed as a gate insulating layer 40 by a wet process.

[A3] Source and Drain Electrode Formation Step Next, the source electrode 20a and the drain electrode 20b are formed on the gate insulating layer 40 (see FIG. 2C).
The source electrode 20a and the drain electrode 20b can be formed using, for example, an etching method, a lift-off method, or the like.

  When the source electrode 20a and the drain electrode 20b are formed by etching, I: First, a metal film (metal layer) is formed on the entire surface of the substrate 10 by using, for example, sputtering, vapor deposition, plating, or the like. . II: Next, a resist layer is formed on the metal film (surface) by using, for example, a photolithography method, a microcontact printing method, or the like. III: Next, using this resist layer as a mask, the metal film is etched and patterned into a predetermined shape.

When the source electrode 20a and the drain electrode 20b are formed by the lift-off method, I: First, a resist layer is formed in a region other than the region where the source electrode 20a and the drain electrode 20b are formed. II: Next, a metal film (metal layer) is formed on the entire surface of the substrate 10 on the resist layer side using, for example, vapor deposition or plating. III: Next, the resist layer is removed.
The source electrode 20a and the drain electrode 20b are necessary after forming a coating film on the gate insulating layer 40 by applying (supplying) a conductive material or a conductive material containing a conductive organic material, for example. Accordingly, post-treatment (for example, heating, infrared irradiation, application of ultrasonic waves, etc.) can be performed on the coating film.
Examples of the conductive material containing conductive particles include a solution in which metal fine particles are dispersed, a polymer mixture containing conductive particles, and the like.
Moreover, as a conductive material containing a conductive organic material, a solution or dispersion of a conductive organic material can be given.

  Examples of the method for applying (supplying) the conductive material on the gate insulating layer 40 include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, Examples thereof include coating methods such as dip coating methods and spray coating methods, screen printing methods, flexographic printing methods, offset printing methods, ink jet methods, printing methods such as microcontact printing methods, etc., one or two of these A combination of more than one species can be used.

[A4] Organic Semiconductor Layer Formation Step Next, the organic semiconductor layer 30 is formed so as to cover the source electrode 20a and the drain electrode 20b (see FIG. 2D).
The organic semiconductor layer 30 supplies a composition for an organic semiconductor layer containing an organic semiconductor material and a solvent for dissolving the organic semiconductor material so as to cover the source electrode 20a and the drain electrode 20b, and then, as necessary. It forms by performing a post-process. In the following, dissolution includes a state in which a solute is finely dispersed, and the solvent includes a dispersion medium (medium) in which the solute is finely dispersed.

First, a composition for an organic semiconductor layer containing an organic semiconductor material and a solvent is prepared.
Here, the organic semiconductor layer 30 is formed using this composition for organic semiconductor layers, and the thin film characteristics of the organic semiconductor layer 30 formed in this way are the solute organic semiconductor material and the solvent. It is supposed to change due to the correlation.

However, until now, no clear knowledge about this correlation has been obtained. For this reason, the material (composition for organic-semiconductor layers) which can obtain the organic-semiconductor layer which has the outstanding thin film characteristic was calculated | required.
Therefore, the present inventor has intensively studied the selection conditions of a solvent for dissolving an organic semiconductor material as a solute with respect to a composition for an organic semiconductor layer capable of forming an organic semiconductor layer having excellent thin film characteristics. As the solvent, the following conditions I and II are satisfied, and the solvent has a second virial coefficient with respect to the organic semiconductor material at 25 ° C. of −1 × 10 ⁻³ to 1 × 10 ⁻³ cm ³ · mol / It found that it is effective be of g ^2, thereby completing the present invention.

Condition I: The organic semiconductor material has a main chain including a π-conjugated structure and a linear side chain branched from at least one position of the repeating unit structure of the main chain and including a plurality of carbon atoms.
Condition II: When the second virial coefficient for the organic semiconductor material is dissolved in a solvent outside the above range (a solvent other than the solvent), the side chains are elongated and the side chains interfere with each other. The flatness of the chain is impaired.
In the above condition II, the solvent whose second virial coefficient for the organic semiconductor material is outside the above range is a solvent that can sufficiently dissolve the organic semiconductor material, and more specifically, for the organic semiconductor material at 25 ° C. It is a solvent having a second virial coefficient exceeding 1 × 10 ⁻³ cm ³ · mol / g ² .

Organic semiconductor materials that satisfy these conditions include a π-conjugated structure in the main chain, and therefore can exhibit high carrier mobility according to the length of the conjugate length, and exhibit excellent thin film characteristics. It can be used as a material for forming a layer.
In addition, since the side chain branched from the main chain includes a linear portion of a plurality of carbon atoms, the affinity for general solvents is high, and the solubility of the organic semiconductor material in the solvent is high. It is increasing.

Here, the second virial coefficient can be an index indicating the degree of interaction in the solvent of the organic semiconductor material which is a solute.
Specifically, when the second virial coefficient shows a positive value, that is, when the solvent is a good solvent for the organic semiconductor material, the higher the value, the more soluble the organic semiconductor material is dissolved in the solvent. Means high.
On the other hand, when the second virial coefficient shows a negative value, that is, when the solvent is a poor solvent for the organic semiconductor material, the smaller the value, the lower the solubility of the organic semiconductor material dissolved in the solvent, It means that the organic semiconductor material is easily deposited.

Further, when the solubility of the solvent in the organic semiconductor material is changed in this way, the side chain (particularly, a portion where the plurality of carbon atoms described above are linear) extends or shortens.
For example, when the second virial coefficient of the solvent shows a positive value, the side chain extends, and when the second virial coefficient of the solvent shows a negative value, the side chain shortens.
When the side chain extends, the extended side chains cause a steric hindrance (interference) to cause deformation such as twisting and bending in the main chain, and the planarity of the molecular structure of the organic semiconductor material is lowered. Thereby, the conjugate length of the organic semiconductor layer formed using the composition for organic semiconductor layers is shortened, and as a result, the carrier mobility of the organic semiconductor layer is lowered.
On the other hand, when the side chain is shortened, the probability that the side chains cause a three-dimensional structural failure (interference) decreases, so that the main chain can be prevented from being twisted or bent, and the planarity is improved. Thereby, the conjugate length of the formed organic semiconductor layer becomes long, and as a result, the carrier mobility of the organic semiconductor layer can be increased.
In addition, such a 2nd virial coefficient can be changed to some extent according to the temperature of a solvent. In general, the second virial coefficient can be slightly increased by increasing the temperature of the solvent within a range that does not involve alteration of the solvent or the organic semiconductor material dissolved in the solvent.

  From the above viewpoint, the second virial coefficient of the solvent with respect to the organic semiconductor material is set in the above-described range. If the range of the second virial coefficient is in the range as described above, the temperature of the solvent is set appropriately to prevent the organic semiconductor material from precipitating, shorten the side chain, and improve the main chain planarity. Can be made. And the conjugate length becomes long in the organic-semiconductor layer 30 formed using such an organic-semiconductor material, Thereby, thin film characteristics, such as carrier mobility of the organic-semiconductor layer 30, can be improved. As a result, for example, the thin film transistor 1 including the organic semiconductor layer 30 can obtain excellent transistor characteristics (for example, increase in drain current value).

By the way, when an organic semiconductor material is dissolved in a predetermined solvent (a solvent having a second virial coefficient of greater than 1 × 10 ⁻³ cm ³ · mol / g ^{2 with} respect to the organic semiconductor material), as described above, the side chain is elongated. Then, whether or not the three-dimensional structural obstacle between the side chains is generated can be determined as follows. That is, when an organic semiconductor material is dissolved in various solvents to form a liquid material (composition for an organic semiconductor layer), the peak wavelength of the absorption spectrum of the liquid material is (A) the refractive index and / or the dielectric constant of the solvent. It can be determined by examining whether it changes according to the change of (B) or according to the change of the second virial coefficient of the solvent.

In the case of (A) The change in the peak wavelength of the absorption spectrum in the liquid material containing the organic semiconductor material as described above is caused by the change in the conjugate length due to the change in the three-dimensional structure of the main chain of the organic semiconductor material.
By the way, in the liquid material containing the organic semiconductor material and the solvent, if there is no interaction between the organic semiconductor material that is the solute and the solvent, the peak wavelength of the absorption spectrum of the liquid material is It is said that it has the property of changing according to changes in refractive index and / or dielectric constant.

Therefore, if the peak wavelength of the absorption spectrum of the liquid material changes according to the change in the refractive index and / or dielectric constant of the solvent, no interaction occurs between the organic semiconductor material that is the solute and the solvent. It is presumed that it is not.
That is, in the case of (A), when the organic semiconductor material is dissolved in a predetermined solvent, it can be determined that there is no steric hindrance between the side chains.

In the case of (B) As described above, the second virial coefficient is an index indicating the degree of interaction in the solvent of the organic semiconductor material that is a solute. Therefore, if the peak wavelength of the absorption spectrum of the liquid material changes according to the change of the second virial coefficient of the solvent, there is some interaction between the organic semiconductor material that is the solute and the solvent. Inferred.
That is, in the case of (B), when the organic semiconductor material is dissolved in a predetermined solvent, it can be determined that a steric hindrance between the side chains occurs.
By considering the above conditions, a solvent suitable for dissolving the organic semiconductor material can be selected. And the composition for organic semiconductor layers containing such organic-semiconductor material and a solvent is highly compatible with the stability which prevents precipitation of organic-semiconductor material, and the outstanding thin film characteristic in the formed organic-semiconductor layer. To get.

  The total carbon number of one side chain of the organic semiconductor material is preferably 4 to 12, and more preferably 6 to 10. The change in the three-dimensional structure (planarity) of the main chain depending on the second virial coefficient of the solvent causes the extended side chains to interfere with each other in a solvent with a large second virial coefficient, resulting in a steric structural hindrance. Is what happens. For this reason, as the number of carbon atoms contained in the side chain increases, the length of the side chain increases and the degree of change in the three-dimensional structure of the main chain increases. Accordingly, if the number of carbon atoms is within the above range, the side chain length is reduced while the solubility of the organic semiconductor material in the solvent is sufficiently maintained, and the side chains adjacent to each other have a steric hindrance ( Interference) can be made to a length that is not particularly likely to occur. As a result, the planarity of the three-dimensional structure of the main chain constituting the organic semiconductor material can be improved, and the carrier mobility of the organic semiconductor layer formed using this organic semiconductor material can be increased.

Further, the linear side chain containing a plurality of carbon atoms may be a hydrocarbon composed of carbon atoms and hydrogen atoms, in which part or all of the hydrogen atoms are substituted with fluorine atoms. May be. Furthermore, the middle or end of the side chain may be branched to have another side chain.
The side chain may have other structures or atoms.
The side chain is particularly preferably an alkyl chain. Since the alkyl chain is mainly composed of a nonpolar portion derived from a C—H bond, the solubility in a solvent can be particularly enhanced.

  Examples of organic semiconductor materials as described above include polyparaphenylene vinylene derivatives represented by the following chemical formulas (1) to (4), and those represented by the following chemical formulas (5) to (8). Examples thereof include polythiophene derivatives, polyparaphenylene derivatives represented by the following chemical formulas (9) and (10), polyfluorene derivatives represented by the following chemical formula (11), and the like.

However, in the chemical formulas (1) to (11), x and y are each independently an integer representing the number of repeating units of the monomer unit, and may be the same or different. A, b, c and d are each independently an integer representing the number of carbon atoms and may be the same or different.
Among these organic semiconductor materials, those containing a thiophene ring such as a polythiophene derivative as the π-conjugated structure of the main chain are preferable. A thiophene ring is particularly excellent in carrier mobility between adjacent thiophene rings, and an organic semiconductor layer formed using an organic semiconductor material containing a thiophene ring in the main chain exhibits excellent carrier mobility.

Moreover, it is preferable that the main chain is composed of a plurality of thiophene rings bonded in a straight chain as in the chemical formulas (5) to (8). Thereby, the conjugated length of the π-conjugated structure becomes longer, and an organic semiconductor layer exhibiting particularly excellent carrier mobility can be obtained.
The number of repeating units in such an organic semiconductor material is preferably about 5 to 6000, and more preferably about 5 to 1000. This makes it easy to synthesize and handle while exhibiting sufficient characteristics as an organic semiconductor material.
The weight average molecular weight of the organic semiconductor material is preferably about 1,000 to 1,000,000, and more preferably about 1,000 to 200,000. This makes it particularly easy to synthesize and handle organic semiconductor materials.

Here, among the above organic semiconductor materials, in the chemical formula (5), poly (3-hexylthiophene) (P3HT) having an alkyl chain with a carbon number n of 6 is used as a representative example, and the second virial coefficient of the solvent is set. The dependent three-dimensional structure change will be described.
FIG. 3 is a diagram (schematic diagram) for explaining the three-dimensional structure of poly (3-hexylthiophene). 3A and 3C are plan views of the molecular structure of P3HT, and FIGS. 3B and 3D are perspective views of the molecular structure of P3HT, respectively.

First, when this organic semiconductor material is dissolved in a predetermined solvent (for example, xylene, chloroform, etc.), as shown in FIG. 3A, the alkyl chain (side chain) widens the contact area with this solvent. As shown in FIG. 3B, the main chain is twisted by the steric hindrance between the extended alkyl chains.
On the other hand, when the second virial coefficient is brought into contact with a solvent having a negative value, as shown in FIG. 3C, the alkyl chain is shortened so as to narrow the contact area with the solvent, and FIG. As shown in the figure, the planarity of the main chain is increased. Such a change in the three-dimensional structure depending on the second virial coefficient of the solvent similarly occurs in other organic semiconductor materials represented by the chemical formulas (1) to (11).

As described above, the second virial coefficient to the organic semiconductor material at 25 ° C. of the solvent contained in the organic semiconductor layer composition of the present ^{invention, -1 × 10 -3 ~1 × 10} -3 cm 3 · mol / G ² , but preferably −1 × 10 ^{−3 to 0} cm ³ · mol / g ² . When the range of the second virial coefficient is such a range, in the composition for an organic semiconductor layer, the side chain is shortened and the planarity of the main chain is reduced while reliably preventing the precipitation of the organic semiconductor material even at room temperature. Can be improved. In addition, the tendency that the planarity of the main chain is improved as the second virial coefficient is smaller within the above range becomes more remarkable. As a result, an organic semiconductor layer excellent in thin film characteristics and a thin film transistor including the organic semiconductor layer and excellent in transistor characteristics can be obtained.
In addition, when this 2nd virial coefficient is smaller than the said lower limit, an organic-semiconductor material will precipitate remarkably and a stable composition for organic-semiconductor layers will not be obtained.

  On the other hand, if the second virial coefficient is larger than the upper limit value, the side chains are remarkably extended, and the extended side chains are very likely to cause a three-dimensional structural obstacle. As a result, the main chain is deformed such as torsion and bending, and the conjugate length is remarkably shortened. As a result, an organic semiconductor layer formed using the composition for an organic semiconductor layer cannot obtain sufficient carrier mobility and has particularly low thin film characteristics.

Examples of the solvent for dissolving the organic semiconductor material include cyclohexane, cyclohexanone, 1,4-dioxane, indane, indene, ethylnaphthalene, methylnaphthalene, benzofuran, trimethylbenzene, xylene, toluene, cyclohexylbenzene, chlorobenzene, and dichlorobenzene. , Chloroform, dichloromethane, trichloroethane, tetrahydronaphthalene, tetrahydrofuran (THF), butane, hexane, heptane, octane, decane, dodecane, tetradecane, hexadecane, mesitylene, tetralin, decalin, anisole, butyl acetate, etc. One or a combination of two or more can be selected, and anisole or trichloroethane is particularly preferable. These solvents can reduce the second virial coefficient within the above range with respect to an organic semiconductor material containing a thiophene ring as the π-conjugated structure of the main chain. Thereby, in the composition for organic semiconductor layers, the planarity of the main chain of the organic semiconductor material can be particularly enhanced.
Moreover, it is preferable that the content rate of the organic-semiconductor material in this composition for organic-semiconductor layers is 0.1-5 wt%, and it is more preferable that it is 0.5-2 wt%. Thereby, an organic semiconductor layer having a sufficient thickness can be formed while reliably preventing the organic semiconductor material from being deposited.

Next, the composition for an organic semiconductor layer as described above is supplied onto the substrate 10 so as to cover the source electrode and the drain electrode.
As a method for supplying the liquid material for forming an organic semiconductor onto the substrate 10, for example, the coating method, the printing method, and the like mentioned in the step [A1] can be used.
Of these, the inkjet method is preferably used. In the ink jet method, since a liquid material can be supplied in a fine pattern, patterning is unnecessary, and an organic semiconductor layer having a precise shape can be formed by a simple process.
In addition, when the organic semiconductor material precursor is contained in the composition for an organic semiconductor layer, an annealing treatment is performed thereafter.

In this way, the organic semiconductor layer 30 is formed so as to cover the source electrode 20a and the drain electrode 20b. At this time, a channel region is formed between the source electrode 20a and the drain electrode 20b.
The formation region of the organic semiconductor layer 30 is not limited to the illustrated configuration, and the organic semiconductor layer 30 may be selectively formed in a region (channel region) between the source electrode 20a and the drain electrode 20b. . Thereby, when a plurality of thin film transistors (elements) 1 are arranged on the same substrate, the leakage current and the crosstalk between the elements are suppressed by independently forming the organic semiconductor layer 30 of each element. Can do. Moreover, the usage-amount of organic-semiconductor material can be reduced and manufacturing cost can also be reduced.
Through the steps as described above, the thin film transistor 1 of the first embodiment is obtained.
The thin film transistor 1 manufactured in this manner has a long conjugated length of the organic semiconductor material contained in the organic semiconductor layer, and has good transistor characteristics because the organic semiconductor layer has good thin film characteristics. Obtainable.

Second Embodiment
Next, 2nd Embodiment of the thin-film transistor manufactured using the composition for organic-semiconductor layers of this invention is described.
FIG. 4: is a schematic sectional drawing which shows 2nd Embodiment of the thin-film transistor manufactured using the composition for organic-semiconductor layers of this invention.

Hereinafter, the thin film transistor of the second embodiment will be described with a focus on differences from the first embodiment, and description of similar matters will be omitted.
The thin film transistor 1 of the second embodiment is the same as the thin film transistor 1 of the first embodiment except that the arrangement positions of the respective electrodes are different.
That is, the thin film transistor 1 illustrated in FIG. 4 is a top-gate thin film transistor in which the source electrode 20a and the drain electrode 20b are located closer to the substrate 10 than the gate electrode 50 through the organic semiconductor layer 30 and the gate insulating layer 40.
And the organic-semiconductor layer 30 is formed using the composition for organic-semiconductor layers similar to the said 1st Embodiment.

Such a thin film transistor 1 can also be manufactured in the same manner as the thin film transistor 1 of the first embodiment.
Also by the thin film transistor 1 of the second embodiment, the same operation and effect as the thin film transistor 1 of the first embodiment can be obtained.
In addition, the electronic device formed by forming an organic semiconductor layer with the composition for an organic semiconductor layer of the present invention is not limited to the application to the thin film transistor as described above, and for example, an organic EL element or a photoelectric conversion element. It can also be applied.

<Electro-optical device>
Next, an electrophoretic display device will be described as an example of the electro-optical device of the present invention in which an active matrix device including the thin film transistor 1 as described above (in which the above-described electronic device is formed on a substrate) is incorporated. Note that an active matrix device is manufactured by forming a plurality of the aforementioned electronic devices on a substrate.

FIG. 5 is a longitudinal sectional view showing an embodiment of the electrophoretic display device, and FIG. 6 is a block diagram showing a configuration of an active matrix device included in the electrophoretic display device shown in FIG.
An electrophoretic display device 200 shown in FIG. 5 includes an active matrix device 300 provided on a substrate 500 and an electrophoretic display unit 400 electrically connected to the active matrix device 300.

As shown in FIG. 6, the active matrix device 300 includes a plurality of data lines 301 orthogonal to each other, a plurality of scanning lines 302, and a thin film transistor 1 provided near each intersection of the data lines 301 and the scanning lines 302. And have.
The gate electrode 50 of the thin film transistor 1 is connected to the scanning line 302, the source electrode 20a is connected to the data line 301, and the drain electrode 20b is connected to a pixel electrode (individual electrode) 401 described later.

As shown in FIG. 5, the electrophoretic display unit 400 includes a pixel electrode 401, a microcapsule 402, a transparent electrode (common electrode) 403, and a transparent substrate 404 that are sequentially stacked on a substrate 500. Yes.
The microcapsule 402 is fixed between the pixel electrode 401 and the transparent electrode 403 by a binder material 405.

The pixel electrodes 401 are divided so as to be regularly arranged in a matrix, that is, vertically and horizontally.
In each capsule 402, an electrophoretic dispersion liquid 420 including a plurality of types of electrophoretic particles having different characteristics, and in this embodiment, two types of electrophoretic particles 421 and 422 having different charges and colors (hues) are encapsulated. Has been.

In such an electrophoretic display device 200, when a selection signal (selection voltage) is supplied to one or a plurality of scanning lines 302, a thin film transistor connected to the scanning line 302 to which the selection signal (selection voltage) is supplied. 1 is turned on.
Thereby, the data line 301 connected to the thin film transistor 1 and the pixel electrode 401 are substantially conducted. At this time, if desired data (voltage) is supplied to the data line 301, this data (voltage) is supplied to the pixel electrode 401.

As a result, an electric field is generated between the pixel electrode 401 and the transparent electrode 403, and the electrophoretic particles 421 and 422 are either one of the electrophoretic particles 421 and 422 depending on the direction and strength of the electric field and the characteristics of the electrophoretic particles 421 and 422. Electrophoresis towards the electrode.
On the other hand, when supply of the selection signal (selection voltage) to the scanning line 302 is stopped from this state, the thin film transistor 1 is turned off, and the data line 301 and the pixel electrode 401 connected to the thin film transistor 1 are in a non-conductive state. Become.
Therefore, by appropriately combining the supply and stop of the selection signal to the scanning line 302 or the supply and stop of the data to the data line 301, the display surface side (transparent substrate 404 side) of the electrophoretic display device 200 is provided. A desired image (information) can be displayed.

In particular, in the electrophoretic display device 200 of the present embodiment, it is possible to display a multi-tone image by changing the colors of the electrophoretic particles 421 and 422.
In addition, since the electrophoretic display device 200 of the present embodiment includes the active matrix device 300, the thin film transistor 1 connected to the specific scanning line 302 can be selectively turned on / off. And the circuit operation can be speeded up, so that a high quality image (information) can be obtained.

In addition, since the electrophoretic display device 200 according to the present embodiment operates with a low driving voltage, power saving can be achieved.
The electro-optical device in which the active matrix device including the thin film transistor 1 as described above is incorporated is not limited to the application to the electrophoretic display device 200. For example, a liquid crystal device, an organic or inorganic EL device is used. The present invention can also be applied to a display device such as a device or a light emitting device.

  In this electro-optical device manufacturing method, for example, in the case of the above-described electrophoretic display device manufacturing method, for the so-called electrophoretic display sheet in which the microcapsules 402 are fixed to the transparent electrode 403 by the binder material 405, It has a manufacturing process for bonding an active matrix device. In addition, for example, in the case of a liquid crystal device, although not shown, the manufacturing method includes attaching an active matrix device to a counter substrate and injecting a liquid crystal material therebetween.

<Electronic equipment>
Such an electrophoretic display device 200 can be incorporated into various electronic devices. Hereinafter, an electronic apparatus of the present invention including the electrophoretic display device 200 will be described.
<< Electronic Paper >>
First, an embodiment when the electronic apparatus of the present invention is applied to electronic paper will be described.
FIG. 7 is a perspective view showing an embodiment when the electronic apparatus of the present invention is applied to electronic paper.
An electronic paper 600 shown in this figure includes a main body 601 composed of a rewritable sheet having the same texture and flexibility as paper, and a display unit 602.
In such electronic paper 600, the display unit 602 includes the electrophoretic display device 200 as described above.

<< Display >>
Next, an embodiment when the electronic apparatus of the present invention is applied to a display will be described.
8A and 8B are diagrams showing an embodiment in which the electronic apparatus of the present invention is applied to a display. FIG. 8A is a cross-sectional view and FIG. 8B is a plan view.
A display 800 shown in this figure includes a main body 801 and an electronic paper 600 that is detachably provided to the main body 801. The electronic paper 600 has the same configuration as described above, that is, the configuration shown in FIG.

  The main body 801 has an insertion port 805 into which the electronic paper 600 can be inserted on the side (right side in the drawing), and two pairs of conveying rollers 802a and 802b are provided inside. When the electronic paper 600 is inserted into the main body 801 through the insertion port 805, the electronic paper 600 is installed in the main body 801 in a state of being sandwiched between the pair of conveyance rollers 802a and 802b.

  Further, a rectangular hole 803 is formed on the display surface side of the main body 801 (the front side in the drawing (b) below), and a transparent glass plate 804 is fitted into the hole 803. Thereby, the electronic paper 600 installed in the main body 801 can be viewed from the outside of the main body 801. That is, in the display 800, the display surface is configured by visually recognizing the electronic paper 600 installed in the main body 801 on the transparent glass plate 804.

In addition, a terminal portion 806 is provided at the leading end portion (left side in the drawing) of the electronic paper 600, and the terminal portion with the electronic paper 600 installed on the main body portion 801 is provided inside the main body portion 801. A socket 807 to which 806 is connected is provided. A controller 808 and an operation unit 809 are electrically connected to the socket 807.
In such a display 800, the electronic paper 600 is detachably installed on the main body 801, and can be carried and used while being detached from the main body 801.
Further, in such a display 800, the electronic paper 600 is configured by the electrophoretic display device 200 as described above.

  Note that the electronic apparatus of the present invention is not limited to the application to the above, and for example, a television, a viewfinder type, a monitor direct view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, an electronic Examples include newspapers, word processors, personal computers, workstations, videophones, POS terminals, and devices equipped with touch panels. The electrophoretic display device 200 can be applied to the display units of these various electronic devices. is there.

Although the organic semiconductor layer composition, the thin film transistor manufacturing method, the active matrix device manufacturing method, the electro-optical device manufacturing method, and the electronic device manufacturing method of the present invention have been described above, the present invention is limited to these. It is not a thing.
In addition, the configuration of each part of the thin film transistor, the active matrix device, the electro-optical device, and the electronic device of the present invention can be replaced with an arbitrary one that can exhibit the same function, or an arbitrary configuration is added. You can also

Next, specific examples of the present invention will be described.
(Example A and Reference Example A )
1-1. Preparation of Liquid Material (Organic Semiconductor Layer Composition of the Present Invention) As shown below, liquid material No. 1-15 were prepared respectively.
((Liquid material No. 1))
A liquid material was prepared by dissolving poly (3-hexylthiophene) (P3HT) (manufactured by Aldrich) in anisole (solvent) at 25 ° C. at a rate of 1 wt%.
((Liquid material No. 2-6))
Except for changing the solvent for dissolving P3HT as shown in Table 1, the liquid material No. In the same manner as in No. 1, a liquid material was prepared.

(Comparative Example A)
((Liquid material No. 7))
A liquid material was prepared by dissolving polyallylamine-based organic semiconductor material (PAA) (manufactured by ADS) represented by the following chemical formula (12) in dichlorobenzene (solvent) at a rate of 1 wt%.

((Liquid material No. 8-15))
Except for changing the solvent of the polyallylamine organic semiconductor material as shown in Table 1, the liquid material No. In the same manner as in Example 7, a liquid material was prepared.
In addition, Table 1 shows the second virial coefficient and refractive index of each solvent.

1-2. Evaluation of Liquid Material For each liquid material, an absorption spectrum was measured, and a wavelength (peak wavelength) at which the absorption spectrum showed a maximum value was examined.
For a liquid material using P3HT as the organic semiconductor material, FIG. 9 shows the relationship between the second virial coefficient of the solvent and the peak wavelength for the organic semiconductor material, and FIG. 10 shows the relationship between the refractive index of the solvent and the peak wavelength. In the horizontal axis of FIG. 9, the liquid materials are arranged in ascending order of the second virial coefficient from the left, and in the horizontal axis of FIG. 10, the liquid materials are arranged in the descending order of the refractive index from the left.

  FIG. 11 shows the relationship between the second virial coefficient of the solvent and the peak wavelength of the liquid material using PAA as the organic semiconductor material, and FIG. 12 shows the relationship between the refractive index of the solvent and the peak wavelength. In the horizontal axis of FIG. 11, the liquid materials are arranged in ascending order of the second virial coefficient from the left, and in the horizontal axis of FIG. 12, the liquid materials are arranged in the descending order of the refractive index.

As shown in FIGS. 9 and 10, in the liquid materials of Example A and Reference Example A using P3HT as the organic semiconductor material, the peak wavelength in the absorption spectrum changes according to the change of the second virial coefficient. Became clear.
On the other hand, as shown in FIGS. 11 and 12, in the liquid material of Comparative Example A using PAA as the organic semiconductor material, the peak wavelength in the absorption spectrum may change according to the change in the refractive index of the solvent. It became clear.
Accordingly, it is recognized that P3HT causes a steric hindrance between side chains when dissolved in a predetermined solvent. On the other hand, since PAA has short side chains and the distance between adjacent side chains is relatively long, it is presumed that such a failure does not occur.

2-1. Production of Thin Film Transistor (Example B and Reference Example B )
As shown below, sample no. 1 to 5 thin film transistors were manufactured.

((Sample No. 1))
First, a glass substrate (manufactured by NEC Corning, “OA10”) was prepared, washed with water, and then dried.
Next, an Ag fine particle aqueous dispersion was applied on a glass substrate by an inkjet method, and then dried at 80 ° C. for 10 minutes. Thereby, a gate electrode having an average thickness of 100 nm and an average width of 30 μm was formed.

Next, a 5 wt% butyl acetate solution of polymethyl methacrylate (PMMA) was applied onto the gate electrode by a spin coating method (2400 rpm), and then dried at 60 ° C. for 10 minutes.
Thereby, a gate insulating layer having an average thickness (total) of 500 nm was formed.
Next, a source electrode and a drain electrode having an average thickness of 100 nm were formed on the gate insulating layer by vapor deposition.
The distance between the source electrode and the drain electrode (channel length L) was 20 μm, and the channel width W was 1 mm.

Next, poly (3-hexylthiophene) (P3HT) (manufactured by Aldrich) was dissolved in anisole at 25 ° C. at a rate of 0.5 wt% to prepare an organic semiconductor layer composition. This composition for organic semiconductor layers was applied on the gate insulating layer by a spin coating method (2400 rpm) and then dried at 60 ° C. for 10 minutes. Thereby, an organic semiconductor layer having an average thickness of 50 nm was formed.
Through the above steps, sample No. 1 thin film transistor was obtained.

((Sample No. 2-5))
Except that the solvent of the organic semiconductor layer composition was changed as shown in Table 2, the sample No. In the same manner as in Example 1, a thin film transistor was manufactured.
(Comparative Example B)
((Sample Nos. 6-7))
Except that the solvent of the organic semiconductor layer composition was changed as shown in Table 2, the sample No. In the same manner as in Example 1, a thin film transistor was manufactured.

2-2. Evaluation of Thin Film Transistor First, the current value of the drain current was measured for each thin film transistor manufactured in each of Example B , Reference Example B, and Comparative Example B under a nitrogen atmosphere.
Here, the current value of the drain current was measured by setting the potential difference between the source electrode and the drain electrode to 40 V and changing the gate voltage value.

In the thin film transistors of each Example B , Reference Example B, and Comparative Example B, the second virial coefficient and refractive index of the solvent of the liquid material (composition for the organic semiconductor layer) used to form the organic semiconductor layer, and the drain current Values are shown in Table 2.
In addition, the current value of the drain current in Table 2 is an average value of 200 thin film transistors.

As shown in Table 2, it was revealed that each of the thin film transistors of Example B had a higher drain current than the thin film transistor of Comparative Example B, and exhibited excellent transistor characteristics.
In addition, among the thin film transistors of each Example B, the current value of the drain current increases as the second virial coefficient of the solvent contained in the composition for the organic semiconductor layer used to form the organic semiconductor layer decreases. As a result, it was revealed that the transistor characteristics were improved.

It is the schematic which shows 1st Embodiment of the thin-film transistor manufactured using the composition for organic-semiconductor layers of this invention. It is a figure (longitudinal sectional drawing) for demonstrating the manufacturing method of the thin-film transistor shown in FIG. It is a figure (schematic diagram) for demonstrating the three-dimensional structure of poly (3-hexyl thiophene). It is a schematic sectional drawing which shows 2nd Embodiment at the time of applying the electronic device of this invention to a thin-film transistor. It is a longitudinal cross-sectional view which shows embodiment of an electrophoretic display apparatus. FIG. 6 is a block diagram illustrating a configuration of an active matrix device included in the electrophoretic display device illustrated in FIG. 5. It is a perspective view which shows embodiment at the time of applying the electronic device of this invention to electronic paper. It is a figure which shows embodiment at the time of applying the electronic device of this invention to a display. In the liquid material prepared in Example A and Reference Example A , it is a graph which shows the relationship between the 2nd virial coefficient of a solvent, and the peak wavelength of an absorption spectrum. In the liquid material prepared in Example A and Reference Example A , it is a graph which shows the relationship between the refractive index of a solvent, and the peak wavelength of an absorption spectrum. In the liquid material prepared by the comparative example A, it is a graph which shows the relationship between the 2nd virial coefficient of a solvent, and the peak wavelength of an absorption spectrum. In the liquid material prepared by the comparative example A, it is a graph which shows the relationship between the refractive index of a solvent, and the peak wavelength of an absorption spectrum.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thin film transistor 10 ... Substrate 20a ... Source electrode 20b ... Drain electrode 20 ... Electrode 30 ... Organic-semiconductor layer 40 ... Gate insulating layer 50 ... Gate electrode 200 ... Electrophoretic display device 300 ... Active Matrix device 301 ··· Data line 302 ··· Scan line 400 ··· Electrophoretic display portion 401 ··· Pixel electrode 402 · · · Microcapsule 420 · · · Electrophoretic dispersion liquid 421 and 422 · · · Electrophoretic particles 403 · · · Transparent electrode 404 ... Transparent substrate 405 ... Binder material 500 ... Substrate 600 ... Electronic paper 601 ... Main unit 602 ... Display unit 800 ... Display 801 ... Main unit 802a, 802b ... Conveying roller pair 803 ... Hole 804 ... Transparent glass plate 805 ... Insertion slot 806 ... End Part 807 ‥‥ socket 808 ‥‥ controller 809 ‥‥ operation unit

Claims (10)

An organic semiconductor material that satisfies the following conditions I and II, and a solvent having a second virial coefficient of −1 × 10 ⁻³ to 1 × 10 ⁻⁴ cm ³ · mol / g ² for the organic semiconductor material at 25 ° C. The composition for organic-semiconductor layers characterized by including.
Condition I: The organic semiconductor material includes a main chain composed of a plurality of thiophene rings bonded in a straight chain, and a side chain branched from at least one position of the main chain and including a plurality of carbon atoms And have.
Condition II: When the organic semiconductor material is dissolved in a solvent whose second virial coefficient with respect to the organic semiconductor material at 25 ° C. is outside the range of −1 × 10 ⁻³ to 1 × 10 ⁻³ cm ³ · mol / g ^2. The side chains extend, the side chains interfere with each other, and the planarity of the main chain is impaired.   The composition for an organic semiconductor layer according to claim 1, wherein the total number of carbon atoms in the side chain is 4 to 12.   The composition for an organic semiconductor layer according to claim 1, wherein the side chain is an alkyl chain. The composition for an organic semiconductor layer according to any one of claims 1 to 3 , wherein the solvent is anisole , dichloromethane, or trichloroethane. The composition for an organic semiconductor layer according to any one of claims 1 to 4 , wherein the organic semiconductor material has a weight average molecular weight of 1,000 to 1,000,000. The composition for an organic semiconductor layer according to any one of claims 1 to 5 , wherein a content of the organic semiconductor material in the composition for an organic semiconductor layer is 0.1 to 5 wt%. A method of manufacturing a thin film transistor comprising a source electrode, a drain electrode, a gate electrode, an organic semiconductor layer, and a gate insulating film that insulates the source electrode and the drain electrode from the gate electrode,
An organic semiconductor material that satisfies the following conditions I and II, and a solvent having a second virial coefficient of −1 × 10 ⁻³ to 1 × 10 ⁻⁴ cm ³ · mol / g ² for the organic semiconductor material at 25 ° C. A method for producing a thin film transistor, wherein the organic semiconductor layer is formed by applying an organic semiconductor layer composition.
Condition I: The organic semiconductor material includes a main chain composed of a plurality of thiophene rings bonded in a straight chain, and a side chain branched from at least one position of the main chain and including a plurality of carbon atoms And have.
Condition II: When the organic semiconductor material is dissolved in a solvent whose second virial coefficient with respect to the organic semiconductor material at 25 ° C. is outside the range of −1 × 10 ⁻³ to 1 × 10 ⁻³ cm ³ · mol / g ^2. The side chains extend, the side chains interfere with each other, and the planarity of the main chain is impaired. A method for manufacturing an active matrix device, comprising the method for manufacturing a thin film transistor according to claim 7 . A method for manufacturing an electro-optical device, comprising the method for manufacturing an active matrix device according to claim 8 . An electronic apparatus manufacturing method comprising the electro-optical device manufacturing method according to claim 9 .

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