JP6950137B2 - Film formation method - Google Patents

Description

The present invention relates to a film forming method for forming an organic film using a raw material solution.

A technique for forming a semiconductor film, an insulating film, or the like on a substrate using a liquid material is known. For example, a method of forming a film on the substrate by using a spray method, a spin coating method, or the like is generally used. Has been done. In particular, in recent years, as a method for easily forming an organic material such as fullerene, it has been studied to form a film on a substrate using a raw material solution in which an organic material such as fullerene is dispersed or dissolved in a solvent. Since fullerene has a thermal conductivity about 100 times lower than that of graphite, the fullerene film is expected to be used as a suitable thermal protective film as compared with a normal carbon film. In addition, since fullerenes have extremely low electrical conductivity, they are expected to be used as an insulating film and as a high-resistance black matrix for color filters. Further, since fullerenes have excellent properties as organic n-type semiconductor molecules, they are expected to be used as organic semiconductor thin films.

As a method for forming a film of such an organic material, Patent Document 1 describes that a semiconductor film made of fullerene is formed by using a vacuum vapor deposition method or a casting method. Further, aromatic hydrocarbons such as benzene, toluene, and mesitylene are exemplified as a solvent for forming a film by using the casting method. However, the film obtained by the casting method described in Patent Document 1 has a rough surface, partially aggregates, the film quality is not uniform, and the electrical characteristics are not sufficiently satisfactory. Further, when the film is formed by the casting method, there is a problem that the residual organic solvent, oxygen, water and the like hinder the electron transport and adversely affect the electrical characteristics of the film. When forming an organic material and using an organic solvent, a vacuum device is required, and since vapor deposition is performed while heating at a high temperature (300 ° C. or higher), the substrates that can be used are limited. It was not an industrially useful method. Further, when water was used, the film formation itself could not be formed and the film formation rate was slow, which was not satisfactory.

Non-Patent Document 1 describes that a thin film containing a fullerene derivative (PCBM) is formed from a raw material solution containing a fullerene derivative (PCBM) and chlorobenzene as a solvent by using a mist deposition method. However, in the method described in Non-Patent Document 1, the mists aggregate with each other to deteriorate the film quality, or the solvent in the mist evaporates before reaching the substrate, so that a stable and good film formation can be performed. There was a problem that was difficult. Further, for example, in the case of forming a fullerene which is a non-polar organic compound, the fullerene itself cannot be formed, and only a fullerene derivative having a polar group chemically modified from the fullerene can be formed. It was difficult to obtain a film that retained the original properties of fullerenes.

Therefore, there is no above-mentioned problem, and even when an organic compound having no polar group is used, good film formation can be performed, and a high-quality organic film can be obtained industrially advantageously. Was long-awaited.

Japanese Unexamined Patent Publication No. 06-029514

Takumi Ikenoue; Shizuo Fujita. Fabrication of transparent conductive film and organic thin-film solar cells by ultrasonic spraying method. Materials, 2012, 61.9: 777-782.

An object of the present invention is to provide a novel film forming method capable of obtaining a high-quality organic film in an industrially advantageous manner.

As a result of diligent studies to achieve the above object, the present inventors atomize or atomize a raw material solution containing at least a film-forming raw material and a solvent, and heat the obtained mist or droplets on a heated substrate. In the method of forming an organic film on the substrate by reacting, the film-forming raw material contains an organic compound having no polar group, and the solvent has a boiling point higher than that of the non-polar solvent and the non-polar solvent. Using a raw material solution containing a high polar solvent so that the volume ratio of the non-polar solvent to the polar solvent is 5: 1 to 1: 1, the thermal reaction is further subjected to the boiling point of the polar solvent. When the film is formed at a lower temperature, a stable and high-quality organic film can be formed with high film quality. For example, fullerene itself having no polar group can be easily formed. It was found that not only the film can be formed, but also the film can be stably formed while maintaining the original characteristics of fullerene, and it has been found that such a film forming method can solve the above-mentioned conventional problems at once.
In addition, after obtaining the above findings, the present inventors have further studied and completed the present invention.

That is, the present invention relates to the following invention.
[1] A raw material solution containing at least a film-forming raw material and a solvent is atomized or atomized, and the obtained mist or droplets are thermally reacted on a heated substrate to form an organic film on the substrate. In the method, the film-forming raw material contains an organic compound having no polar group, and the solvent is a non-polar solvent and a polar solvent having a boiling point higher than that of the non-polar solvent. A method for forming an organic film, which comprises a volume ratio of 5: 1 to 1: 1 with a solvent, and the thermal reaction is carried out at a temperature lower than the boiling point of the polar solvent.
[2] The film forming method according to the above [1], wherein the organic compound is a cyclic organic compound.
[3] The film forming method according to the above [1] or [2], wherein the organic compound is a polycyclic organic compound.
[4] The film forming method according to any one of [1] to [3], wherein the solubility of the organic compound in the polar solvent at 25 ° C. is less than 1.0 mg / mL.
[5] The film forming method according to any one of [1] to [4], wherein the volume ratio of the non-polar solvent to the polar solvent is 4: 1 to 7: 3.
[6] The film forming method according to any one of [1] to [5] above, wherein the polar solvent is an aprotic polar solvent.
[7] The film forming method according to any one of the above [1] to [6], wherein the non-polar solvent is an aromatic compound.
[8] The film forming method according to any one of [1] to [7], wherein the boiling point difference between the polar solvent and the non-polar solvent is 50 ° C. or higher.
[9] The film forming method according to any one of [1] to [8], wherein the atomization or droplet formation is performed using ultrasonic vibration.
[10] The film forming method according to any one of [1] to [9], wherein the thermal reaction is carried out at a temperature of 210 ° C. or lower.

According to the film forming method of the present invention, a high-quality organic film can be obtained industrially.

It is a schematic block diagram of the film forming apparatus used in an Example. It is a figure which shows the result of the ultraviolet absorption measurement in an Example. It is a figure which shows the measurement result of the IV characteristic in an Example.

In the film-forming method of the present invention, a raw material solution containing at least a film-forming raw material and a solvent is atomized or dropletized, and the obtained mist or droplets are thermally reacted on a heated substrate to be organically formed on the substrate. A method of forming a film, wherein the film-forming raw material contains an organic compound having no polar group, and the solvent is a non-polar solvent and a polar solvent having a boiling point higher than that of the non-polar solvent. It is characterized in that the volume ratio of the solvent to the polar solvent is 5: 1 to 1: 1 and the thermal reaction is carried out at a temperature lower than the boiling point of the polar solvent.

(Hypokeimenon)
The substrate is not particularly limited as long as it can support the film to be formed. The material of the substrate is not particularly limited as long as it does not interfere with the object of the present invention, and may be a known substrate, an organic compound, or an inorganic compound. It may be a porous structure.

Further, a film having at least one of a metal film, a semiconductor film, a conductive film and an insulating film formed on a part or all of the surface can also be preferably used as the substrate. As the constituent metal of the metal film, for example, one selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium and barium, or one of them. Two or more kinds of metals and the like can be mentioned. Examples of the constituent materials of the semiconductor film include simple elements such as silicon and germanium, compounds having elements of groups 3 to 5 and groups 13 to 15 of the periodic table, metal oxides, and metal sulfides. , Metal serene compounds, metal nitrides and the like. Examples of the constituent material of the conductive film include tin-doped indium oxide (ITO), fluorine-doped indium oxide (FTO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO). , Tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), tungsten oxide (WO ₃ ) and the like, but in the present invention, a conductive film made of a conductive oxide is preferable, and tin dope is used. More preferably, it is an indium oxide (ITO) film. Examples of the constituent material of the insulating film include aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), and silicon oxynitride (Si _4). Examples thereof include O ₅ N ₃ ), and an insulating film made of an insulating oxide is preferable, and a titania film is more preferable.

The means for forming the metal film, the semiconductor film, the conductive film and the insulating film is not particularly limited and may be a known means. Examples of such forming means include a mist CVD method, a sputtering method, a CVD method (vapor deposition method), an SPD method (spray thermal decomposition deposition method), a vapor deposition method, an ALD (atomic layer deposition) method, and a coating method ( For example, dipping, dripping, doctor blade, inkjet, spin coating, brush coating, spray coating, roll coater, air knife coating, curtain coating, wire bar coating, gravure coating, inkjet coating, etc.).

The shape of the substrate may be any shape and is effective for any shape, for example, plate-like, fibrous, rod-like, columnar, prismatic, such as a flat plate or a disk. Cylindrical, spiral, spherical, ring-shaped and the like can be mentioned, but in the present invention, a substrate is preferable. The thickness of the substrate is not particularly limited in the present invention, but is preferably 0.5 μm to 100 mm, more preferably 1 μm to 10 mm. The substrate is not particularly limited as long as it has a plate shape and serves as a support for a film to be formed. It may be an insulator substrate, a semiconductor substrate, a metal substrate, or a conductive substrate. In the present invention, the substrate is preferably a glass substrate.

In the present invention, it is preferable that the substrate contains the conductive film in a part or all of the surface, the substrate is a glass substrate, and the conductive film is further contained in a part or all of the surface. Is more preferable, the substrate is a glass substrate, and it is most preferable that a tin-doped indium oxide film is contained in a part or all of the surface.

(Atomization / droplet formation process)
The atomization / droplet atomization step atomizes or dropletizes the raw material solution. The atomizing means or the droplet forming means is not particularly limited as long as the raw material solution can be atomized or dropletized, and may be a known means. However, in the present invention, the atomizing means or the atomizing means using ultrasonic waves or Dropletization means is preferred. The mist or droplet obtained by using ultrasonic waves has a zero initial velocity and is preferable because it floats in the air. Since it is a possible mist, it is not damaged by collision energy, so it is very suitable. The droplet size is not particularly limited and may be a droplet of about several mm, but is preferably 50 μm or less, and more preferably 100 nm to 10 μm.

(Raw material solution)
The raw material solution contains an organic compound having no polar group as a film-forming raw material, and a non-polar solvent and a polar solvent having a boiling point higher than that of the non-polar solvent are used as a solvent. It is not particularly limited as long as it is contained so as to have a volume ratio of 5: 1 to 1: 1 and can be atomized or atomized. The raw material solution may further contain an inorganic material or an organic material as long as the object of the present invention is not impaired. In addition, the raw material solution may contain both inorganic and organic materials.

The organic compound is not particularly limited as long as it is an organic compound having no polar group. The polar group is a functional group having a polarity or a group having an atomic group having a polarity, and specifically, for example, a hydroxy group, a cyano group, an alkoxy group, a carboxy group, an amino group, a carbonyl group, a nitro group, and the like. A thiol group, a sulfonyl group, a phosphonyl group, a halogen group, an ester group, an epoxy group, a group containing a fluorine atom, a group containing a sulfur atom, a group containing a lactone skeleton, a group containing an acetal structure, a group containing an ester bond, or an ether. Examples include polar groups such as groups containing a bond. The organic compound having no polar group is not particularly limited as long as it is an organic compound having none of the above groups. The organic compound having no polar group may be a cyclic organic compound or an acyclic organic compound, but in the present invention, it is preferably a cyclic organic compound. Examples of the cyclic organic compound include polycyclic organic compounds and monocyclic organic compounds. Examples of the polycyclic organic compound include naphthalene, anthracene, phenanthrene, methylnaphthalene, ethylnaphthalene, naphthalene, pentacene, pyrene, picene, triphenylene, anthancerene, acenaphthylene, acenaphthylene, benzopyrene, benzofluorene, benzophenanthrene, and benzoperylene. Examples thereof include coronene, chrysene, hexabenzoperylene, perylene or fullerene. Examples of the monocyclic organic compound include benzene, toluene, xylene, biphenyl, alkylbenzene, cumene and the like. In the present invention, the organic compound is preferably a cyclic organic compound, more preferably a polycyclic organic compound, and most preferably a fullerene.

The fullerene may be a chemically modified fullerene derivative or a non-chemically modified fullerene as long as it does not have the polar group, but in the present invention, the fullerene is not chemically modified. It is preferably fullerene. In the present invention, even when fullerenes that have not been chemically modified are used, good film formation can be performed. Examples of the fullerene include C36 fullerene, C60 fullerene, C70 fullerene, C76 fullerene, C78 fullerene, C82 fullerene, C84 fullerene, C90 fullerene, C96 fullerene and the like. In the present invention, the fullerene is preferably C60 fullerene.

The film-forming raw material is not particularly limited as long as it contains the organic compound having no polarity, and may further contain additives and the like. The additive is not particularly limited and may be a known additive as long as the object of the present invention is not impaired. The blending ratio of the additive in the film-forming raw material is not particularly limited, but is preferably 0.00001 mol% to 30 mol%, more preferably 0.0001 mol% to 10 mol%.

The blending ratio of the film-forming raw material in the raw material solution is not particularly limited, but is preferably 0.001% by weight to 80% by weight, and more preferably 0.01% by weight to 80% by weight.

The non-polar solvent can be used as a solvent, and is not particularly limited as long as it has a boiling point lower than that of the polar solvent and does not have polarity. Examples of the non-polar solvent include hydrocarbon compounds and aromatic compounds. In the present invention, the non-polar solvent is preferably an aromatic compound because it can form a better film, and more preferably a compound represented by the following formula (1). ..

（式中、Ｒ^１〜Ｒ^６は、それぞれ同一または異なって、水素原子または炭化水素基を表し、Ｒ^１〜Ｒ^６から選ばれる任意の２つの基が結合して環を形成してもよい。）

(In the formula, R ^{1 to} R ⁶ represent hydrogen atoms or hydrocarbon groups, respectively, which are the same or different, and ^{any two groups selected from R 1 to} R ⁶ may be bonded to form a ring. .)

In the present invention, the non-polar solvent is preferably an alkyl aromatic compound. The alkyl aromatic compound is not particularly limited as long as it is an aromatic compound having one or more alkyl groups.

The "alkyl group" in the present invention is preferably a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group include, for example, methyl, ethyl, n-propyl, 2-propyl, n-butyl, 1-methylpropyl, 2-methylpropyl, tert-butyl, n-pentyl, 1-methylbutyl, 1-. Ethylpropyl, tert-pentyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, n-hexyl, 1-methylpentyl, 1-ethylbutyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2-Methylpentane-3-yl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl , 1-ethylbutyl, 2-ethylbutyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecil, icosyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like. As the alkyl group, an alkyl group having 1 to 10 carbon atoms is more preferable, an alkyl group having 1 to 6 carbon atoms is further preferable, and an alkyl group having 1 to 4 carbon atoms is particularly preferable.

Examples of the hydrocarbon group include an alkyl group, an aryl group, an aralkyl group and the like.

Examples of the alkyl group include the above-mentioned alkyl group and the like.

As the aryl group, an aryl group having 6 to 20 carbon atoms is preferable. Specific examples of the aryl group include phenyl, indenyl, pentarenyl, naphthyl, azulenyl, fluorenyl, phenanthrenyl, anthracenyl, acenaphthylenyl, biphenylenyl, naphthacenyl, pyrenyl and the like. The aryl group is more preferably an aryl group having 6 to 14 carbon atoms.

As the aralkyl group, an aralkyl group having 7 to 20 carbon atoms is preferable. Specific examples of the aralkyl group include benzyl, phenethyl, 1-phenylpropyl, 2-phenylpropyl, 3-phenylpropyl, 1-phenylbutyl, 2-phenylbutyl, 3-phenylbutyl, 4-phenylbutyl, 1-. Phenylpentylbutyl, 2-phenylpentylbutyl, 3-phenylpentylbutyl, 4-phenylpentylbutyl, 5-phenylpentylbutyl, 1-phenylhexylbutyl, 2-phenylhexylbutyl, 3-phenylhexylbutyl, 4-phenylhexyl Butyl, 5-phenylhexylbutyl, 6-phenylhexylbutyl, 1-phenylheptyl, 1-phenyloctyl, 1-phenylnonyl, 1-phenyldecyl, 1-phenylundecyl, 1-phenyldodecyl, 1-phenyltridecyl Alternatively, 1-phenyltetradecyl and the like can be mentioned. The aralkyl group is more preferably an aralkyl group having 7 to 12 carbon atoms.

In the present invention, it is also preferable that any two groups selected from ^{R 1 to} R ^{6 are condensed to form a ring in the above formula (1).} Examples of the ring formed by condensing any two groups selected from R ^{1 to} R ^{6 include a 5- to 20-membered ring.} Preferred rings to be formed include, for example, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclodecane ring, cyclododecane ring, cyclotetradecane ring, cyclopentadecane ring, cyclohexadecane ring, cycloheptadecane ring and the like. Monocyclic; Examples thereof include a fused ring such as a dihydronaphthalene ring, an indene ring or an indan ring. Further, these rings may be substituted with a hydrocarbon group or the like. Specific examples of the hydrocarbon group include those described in the above-mentioned hydrocarbon group.

Specific examples of the alkyl aromatic compounds include alkylbenzenes such as toluene, xylene, trimethylbenzene, ethylbenzene, ethyltoluene, ethylxylenes, diethylbenzenes and propylbenzenes, or methylnaphthalene and ethylnaphthalene. Examples thereof include alkylnaphthalene such as dimethylnaphthalene, and other alkylbiphenyls and alkylanthracenes. In the present invention, the alkyl aromatic compound is preferably trimethylbenzene. Examples of the trimethylbenzene include 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene and the like. In the present invention, the trimethylbenzene is preferably 1,3,5-trimethylbenzene.

The boiling point of the non-polar solvent is not particularly limited as long as it is lower than the boiling point of the polar solvent. In the present invention, the boiling point of the non-polar solvent is preferably 200 ° C. or lower, more preferably 100 ° C. to 200 ° C. Further, the boiling point difference between the polar solvent and the non-polar solvent is not particularly limited, but in the present invention, 30 ° C. or higher is preferable because more stable film formation can be performed. The above is more preferable, and the temperature of 70 ° C. or higher is most preferable. Here, the boiling point means the boiling point under atmospheric pressure. The solubility of the organic compound in the non-polar solvent at 25 ° C. is preferably 1.0 mg / mL or more, and more preferably 1.5 mg / mL or more. Here, the solubility means the mass (mg) of the organic compound dissolved in 1.0 mL of the non-polar solvent at 25 ° C. In the present invention, for convenience, the organic compound is charged into 1.0 mL of a non-polar solvent, and the amount of the organic compound remaining when the saturation concentration is reached or higher is subtracted from the input amount of the organic compound for measurement. be able to.

The polar solvent is not particularly limited as long as it can be used as a solvent, has polarity, and has a boiling point higher than that of the non-polar solvent. It may be an inorganic solvent such as water or an organic solvent. Examples of the water include pure water, ultrapure water, tap water, well water mineral spring water, mineral water, hot spring water, spring water, fresh water, seawater and the like.

Examples of the organic solvent include a protic polar solvent and an aprotic polar solvent. Examples of the protic polar solvent include alcohol solvents, carboxylic acid solvents, phenol solvents, amine solvents and the like. Examples of the alcohol solvent include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, methoxymethanol, methoxyethanol, methoxypropanol, methoxybutanol, ethylene glycol, propylene glycol and the like. Examples of the carboxylic acid solvent include formic acid, acetic acid, propionic acid, butyric acid and the like.

Examples of the aprotonic polar solvent include one or more selected from amide-based solvents, lactone-based solvents, sulfoxide-based solvents, nitrile-based solvents, organic phosphorus-based solvents, and cellosolve-based solvents. Examples of the amide solvent include N, N-dimethylacetamide, N-methyl-pyrrolidone, 2-pyrrolidone, N-methylcaprolactum, N, N-dimethylformamide, N, N-diethylformamide, N, N-diethyl. Examples thereof include acetamide, N-methylpropionamide and methylimidazolidinone. Examples of the lactone-based solvent include β-lactones such as β-propiolactone and β butyrolactone, γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprilolactone, and γ such as γ-laurolactone. -Lactones, δ-lactones such as δ-valerolactone, ε-lactones such as ε-caprolactone, and the like can be mentioned. Examples of the sulfoxide solvent include dimethyl sulfoxide, diethyl sulfoxide, methylphenyl sulfoxide, tetramethylene sulfoxide and the like. Examples of the nitrile solvent include benzonitrile, acetonitrile, propionitrile, butyronitrile, adiponitrile and the like. Examples of the organophosphorus solvent include tetramethylphosphoric amide and hexamethylphosphoric amide. Examples of the cellosolve-based solvent include ethyl cellosolve acetate and methyl cellosolve acetate.

In the present invention, the polar solvent is preferably an organic solvent, more preferably an aprotic polar solvent, and most preferably an amide-based solvent.

The boiling point of the polar solvent is not particularly limited as long as it is higher than the boiling point of the non-polar solvent, but in the present invention, it is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and 200 ° C. to 200 ° C. Most preferably, it is 300 ° C. Here, the boiling point means the boiling point under atmospheric pressure. The solubility of the organic compound in the polar solvent at 25 ° C. is preferably less than 1.0 mg / mL. Here, the solubility means the mass (mg) of the organic compound dissolved in 1.0 mL of the polar solvent at 25 ° C. In the present invention, for convenience, the organic compound is charged into 1.0 mL of a polar solvent, and the amount of the organic compound remaining when the saturation concentration is reached or higher is subtracted from the charged amount of the organic compound for measurement. Can be done. In the present invention, by using a solvent containing a polar solvent having a low solubility of the organic compound as the solvent, the raw material solution more suitable for atomization or droplet formation can be obtained.

The mixing ratio of the polar solvent in the raw material solution is not particularly limited, but is preferably 0.0001 mol% to 90 mol%, more preferably 0.001 mol% to 50 mol%. The blending ratio of the non-polar solvent in the raw material solution is not particularly limited, but is preferably 0.01 mol% to 99 mol%, and more preferably 1 mol% to 95 mol%. Further, in the present invention, the volume ratio of the non-polar solvent to the polar solvent is preferably 4: 1 to 7: 3, because a raw material solution more suitable for atomization or droplet formation can be obtained. ..

The raw material solution may further contain additives. The additive is not particularly limited as long as it does not interfere with the object of the present invention, and may be an acid, a base, a solvent, or the like, and may be a known additive. It may be an inorganic material or an organic material. Examples of the acid include fluoroacid, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, nitric acid, acetic acid, carbonic acid, formic acid, benzoic acid, chloric acid, hypochlorous acid, sulfite, and the following. Examples thereof include protonic acids such as sulfite, nitrite, hyponitrite, phosphite, hypophosphoric acid, and mixtures thereof. Examples of the base include sodium hydroxide, potassium hydroxide, calcium hydroxide, or a mixture thereof. The solvent is not particularly limited as long as it does not impair the object of the present invention, and may be an organic solvent other than the polar solvent or the non-polar solvent, or an inorganic solvent. It may be a mixed solvent of an organic solvent and an inorganic solvent. Examples of the organic solvent include alcohols, esters, ethers and the like. Examples of the inorganic solvent include water and the like, and more specific examples thereof include pure water, ultrapure water, tap water, well water mineral spring water, mineral water, hot spring water, spring water, fresh water, seawater and the like.

The raw material solution is obtained by mixing at least the film-forming raw material and the solvent. The mixing means is not particularly limited and may be a known mixing means. More specifically, for example, it is obtained by dissolving the organic compound in the polar solvent and the non-polar solvent.

In the present invention, it is preferable to carry the mist or the droplets to the substrate with a carrier gas. The carrier gas is not particularly limited as long as the object of the present invention is not impaired, and for example, an inert gas such as oxygen, ozone, nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas is a suitable example. Can be mentioned. Further, the type of the carrier gas may be one type, but may be two or more types, and a diluted gas having a reduced flow rate (for example, a 10-fold diluted gas) or the like is further used as the second carrier gas. May be good. Further, the carrier gas may be supplied not only at one location but also at two or more locations. The flow rate of the carrier gas is not particularly limited, but is preferably 0.01 to 20 L / min, and more preferably 1 to 10 L / min. In the case of a diluting gas, the flow rate of the diluting gas is preferably 0.01 to 10 L / min, more preferably 0.1 to 4 L / min.

(Film formation process)
In the film forming step, the mist or the droplets are thermally reacted on the heated substrate at a temperature lower than the boiling point of the polar solvent to form a film on the substrate. The thermal reaction may be carried out as long as the mist or droplets react with heat on the heated substrate by heating the substrate, and the reaction conditions and the like are not particularly limited as long as the object of the present invention is not impaired. In this step, the thermal reaction is carried out at a temperature lower than the boiling point of the polar solvent, but in the present invention, 210 ° C. or lower is preferable. The lower limit is not particularly limited as long as the object of the present invention is not impaired, but 100 ° C. or higher is preferable, and 120 ° C. or higher is more preferable. Further, the thermal reaction may be carried out in any of a vacuum, a non-oxygen atmosphere, a reducing gas atmosphere and an oxygen atmosphere as long as the object of the present invention is not impaired, but the thermal reaction may be carried out in a non-oxygen atmosphere or oxygen. It is preferably performed in an atmosphere. Further, it may be carried out under any conditions of atmospheric pressure, pressurization and depressurization, but in the present invention, it is preferably carried out under atmospheric pressure. The film thickness can be set by adjusting the film formation time.

Further, in the present invention, a film may be formed directly on the substrate, or may be formed via another layer such as a buffer layer (buffer layer) or a stress relaxation layer. The means for forming other layers such as the buffer layer (buffer layer) and the stress relaxation layer is not particularly limited and may be known means, but in the present invention, the mist CVD method is preferable.

By forming the film as described above, a high-quality organic film can be obtained industrially. Further, the film thickness of the obtained film can be easily adjusted by adjusting the film formation time.

The organic film is useful for various purposes as, for example, an organic insulating film, an organic semiconductor film, a conductive organic film, or the like. In the present invention, it is preferable to use the organic film as an organic semiconductor film in a transistor, a photoelectric conversion device, or the like.

Hereinafter, examples of the present invention will be described, but the present invention is not limited thereto.

(Example 1)
1. 1. Film-forming device The film-forming device 1 used in this embodiment will be described with reference to FIG. The film forming apparatus 1 includes a carrier gas source 2a for supplying a carrier gas, a flow control valve 3a for adjusting the flow rate of the carrier gas sent out from the carrier gas source 2a, and a carrier gas (diluted) for supplying the carrier gas (diluted). Diluted) supply source 2b, flow control valve 3b for adjusting the flow rate of carrier gas (diluted) sent out from the carrier gas (diluted) supply means 2b, mist generation source 4 containing the raw material solution 4a, and water. A container 5 in which 5a is placed, an ultrasonic transducer 6 attached to the bottom surface of the container 5, a hot plate 8, a substrate 10 placed on the hot plate 8, and a mist source 4 to the vicinity of the substrate 10. It is provided with a supply pipe 9 for connecting the gas.

2. Preparation of raw material solution C60 fullerene, mesitylene (solubility of C60 fullerene at 25 ° C.: 1.5 mg / mL) and 2-pyrrolidone (solubility of C60 fullerene at 25 ° C.: about 0 mg / mL) were mixed and used as the raw material solution. bottom. The mixing ratio of mesitylene and 2-pyrrolidone in the solution was 3: 1 (volume ratio), and the concentration of C60 fullerene in the solution was 1.4 × 10 ^-3 mol / L.

3. 3. Preparation for film formation 2. The raw material solution 4a obtained in 1 above was housed in the mist source 4. Next, as the substrate 10, a glass / ITO substrate (20 mm × 25 mm) was placed on the hot plate 8 and the hot plate 8 was operated to raise the temperature of the substrate 10 to 210 ° C. Next, the flow rate control valves 3a and 3b are opened so that the flow rate of the carrier gas supplied from the carrier gas supply source 2a is 2.0 L / min, and the flow rate of the carrier gas (dilution) supplied from the carrier gas (dilution) 2b is set to 2.0 L / min. The flow rate was adjusted to 4.0 L / min. Nitrogen was used as the carrier gas.

4. Formation of fullerene film Next, the ultrasonic transducer 6 is vibrated at 2.4 MHz, and the vibration is propagated to the raw material solution 4a through water 5a to atomize the raw material solution 4a and generate mist 4b. rice field. This mist 4b is conveyed to the substrate 10 by the carrier gas through the inside of the supply pipe 9, and the mist thermally reacts in the vicinity of the substrate 10 heated at 210 ° C. under atmospheric pressure on the substrate 10. A fullerene film was formed. The film thickness of the obtained fullerene film was about 50 nm.

5. Evaluation Above 4. Ultraviolet-visible absorption measurement was performed on the fullerene film obtained in the above. The result is shown in FIG. As can be seen from FIG. 2, the obtained fullerene film had an absorption peak in the wavelength range of 300 nm to 400 nm. In addition, the transistor output characteristics of the obtained fullerene film were measured. The result is shown in FIG. As can be seen from FIG. 3, the obtained fullerene film had good n-type semiconductor characteristics in which the drain current was modulated as the gate voltage increased from 0 V to 60 V.

(Example 2)
A fullerene film was formed in the same manner as in Example 1 except that the film forming temperature was 180 ° C. The obtained fullerene film was subjected to ultraviolet absorption measurement in the same manner as in Example 1. The result is shown in FIG. As can be seen from FIG. 2, the fullerene film obtained in Example 2 had an absorption peak in the wavelength range of 300 nm to 400 nm.

(Examples 3 to 4)
As Examples 3 and 4, a fullerene film was formed in the same manner as in Example 1 except that the film formation temperatures of Example 1 were set to 150 ° C. and 120 ° C., respectively. Ultraviolet-visible absorption measurement was performed on each of the obtained fullerene films in the same manner as in Example 1. As a result, all of the obtained fullerene films had an absorption peak in the wavelength range of 300 nm to 400 nm.

(Examples 5 to 8)
As Examples 5 to 8, fullerenes were obtained in the same manner as in Examples 1 to 4 except that the mixing ratio of mesitylene and 2-pyrrolidone in Examples 1 to 4 was 4: 1 (volume ratio), respectively. A film was formed. Ultraviolet-visible absorption measurement was performed on each of the obtained fullerene films in the same manner as in Example 1. As a result, all of the obtained fullerene films had an absorption peak in the wavelength range of 300 nm to 400 nm.

(Examples 9 to 12)
Fullerenes of Examples 9 to 12 are the same as those of Examples 1 to 4, except that the mixing ratio of mesitylene and 2-pyrrolidone of Examples 1 to 4 is 7: 3 (volume ratio), respectively. A film was formed. Ultraviolet-visible absorption measurement was performed on each of the obtained fullerene films in the same manner as in Example 1. As a result, all of the obtained fullerene films had an absorption peak in the wavelength range of 300 nm to 400 nm.

(Comparative Example 1)
The film was formed in the same manner as in Example 1 except that the mixing ratio of mesitylene and 2-pyrrolidone was 10: 1 (volume ratio). As a result, the film quality was very poor, and the film formation rate was 1/10 or less of that of Example 1.

(Comparative Example 2)
The film was formed in the same manner as in Example 1 except that the mixing ratio of mesitylene and 2-pyrrolidone was 2: 3 (volume ratio). As a result, almost no mist was generated and the film could not be formed.

(Comparative Example 3)
A film was formed in the same manner as in Example 1 except that only mesitylene was used as a solvent. As a result, no film was attached and the adhesion was poor. The film formation rate was also 1/10 or less of that of Example 1.

(Comparative Example 4)
The film was formed in the same manner as in Example 1 except that only 2-pyrrolidone was used as a solvent. However, C60 fullerene was hardly soluble in the solvent, and it was difficult to atomize it, so that a film could not be formed.

The film forming method of the present invention can easily and easily form a high-quality organic film even when an organic compound having no polar group is used as a film forming raw material, and particularly at low temperature and high temperature. Since the film can be formed under atmospheric pressure and non-vacuum, it can be used in a wide variety of fields without restrictions such as a substrate. Further, the organic film obtained by using the film forming method of the present invention can be suitably used for, for example, a photoelectric conversion device or the like.

1 Formation device 2a Carrier gas source 2b Carrier gas (dilution) source 3a Flow control valve 3b Flow control valve 4 Mist generation source 4a Raw material solution 4b Mist 5 Container 5a Water 6 Ultrasonic transducer 7 Nozzle 8 Hot plate 9 Supply pipe 10 substrate

Claims (10)

A method in which a raw material solution containing at least a film-forming raw material and a solvent is atomized or atomized, and the obtained mist or droplets are thermally reacted on a heated substrate to form an organic film on the substrate. The film-forming raw material contains an organic compound having no polar group, and the solvent is a non-polar solvent and a polar solvent having a boiling point higher than that of the non-polar solvent. A method for forming an organic film, which comprises a volume ratio of 5: 1 to 1: 1 and wherein the thermal reaction is carried out at a temperature lower than the boiling point of the polar solvent. The film forming method according to claim 1, wherein the organic compound is a cyclic organic compound. The film forming method according to claim 1 or 2, wherein the organic compound is a polycyclic organic compound. The film forming method according to any one of claims 1 to 3, wherein the solubility of the organic compound in the polar solvent at 25 ° C. is less than 1.0 mg / mL. The film forming method according to any one of claims 1 to 4, wherein the volume ratio of the non-polar solvent to the polar solvent is 4: 1 to 7: 3. The film forming method according to any one of claims 1 to 5, wherein the polar solvent is an aprotic polar solvent. The film forming method according to any one of claims 1 to 6, wherein the non-polar solvent is an aromatic compound. The film forming method according to any one of claims 1 to 7, wherein the boiling point difference between the polar solvent and the non-polar solvent is 50 ° C. or more. The film forming method according to any one of claims 1 to 8, wherein the atomization or droplet formation is performed using ultrasonic vibration. The film forming method according to any one of claims 1 to 9, wherein the thermal reaction is carried out at a temperature of 210 ° C. or lower.

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