JP6980182B2 - Ultrasonic mist - Google Patents

Description

The present invention relates to an ultrasonic mist useful for film formation or the like using a mist containing a film forming raw material.

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 a 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 forming a fullerene film 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 problems in quality such as a rough surface, partial agglutination, and uneven film quality. Further, when the film is formed by the casting method, the coating film formed on the substrate is heat-treated because a residue such as an organic solvent, oxygen, and water that hinders electron transport is generated as it is. I needed it. When the heat treatment is performed, the network structure of the organic semiconductor layer is accidentally formed by the phase separation by heating, so that a sufficient charge transport path cannot be secured and the characteristics of the organic semiconductor film are deteriorated. There were also challenges. When the vacuum vapor deposition method is used, a vacuum device is required, and since vapor deposition is performed while heating at a high temperature (500 ° C. or higher), the substrates that can be used are limited, which is an industrially useful method. It wasn't.

Non-Patent Document 1 describes forming a thin film containing a fullerene derivative (PCBM) 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, it is difficult to stably and goodly form a film because the mist aggregates with each other and the film quality deteriorates, or the solvent in the mist evaporates before reaching the substrate. There was a problem. Further, for example, in the case of forming a fullerene into a film, the fullerene itself cannot be formed, and only a fullerene derivative obtained by chemically modifying the fullerene can form a film. Therefore, a film having the original characteristics of the fullerene can be obtained. Was difficult.

Therefore, there has been a long-awaited industrially useful film forming method capable of stably forming a film with high film forming quality without the above-mentioned problems.

Japanese Unexamined Patent Publication No. 06-029514

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

An object of the present invention is to provide a novel ultrasonic mist capable of forming an industrially advantageous film with high film forming quality.

As a result of diligent studies to achieve the above object, the present inventors have obtained an ultrasonic mist containing at least a film-forming raw material and two or more kinds of solvents, wherein the solvent is a first solvent and a first solvent. Using an ultrasonic mist containing a second solvent having a boiling point and a viscosity at 25 ° C. higher than that of the solvent so that the volume ratio of the first solvent to the second solvent is 5: 1 to 1: 1. When a film is formed, it is possible to stably form a film with high film formation quality. For example, when forming a film of fullerene itself, it was found that the film can be stably formed while maintaining the original characteristics of fullerene. It has been found that such an ultrasonic mist 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] An ultrasonic mist containing at least a film-forming raw material and two or more kinds of solvents, wherein the solvent is a first solvent and a second solvent having a boiling point and a viscosity at 25 ° C. higher than those of the first solvent. The ultrasonic mist is characterized in that the volume ratio of the first solvent to the second solvent is 5: 1 to 1: 1.
[2] The ultrasonic mist according to [1] above, wherein the viscosity of the first solvent at 25 ° C. is 1.0 mPa · s or less [3] The viscosity of the second solvent at 25 ° C. is 1.5 mPa · s. The ultrasonic mist according to the above [1] or [2].
[4] The above-mentioned [1] to [3], wherein the solubility of the film-forming raw material in the first solvent at 25 ° C. is higher than the solubility of the film-forming raw material in the second solvent at 25 ° C. Ultrasonic mist.
[5] The ultrasonic mist according to any one of the above [1] to [4], wherein the volume ratio of the first solvent to the second solvent is 4: 1 to 7: 3.
[6] The ultrasonic mist according to any one of the above [1] to [5], wherein the film forming raw material contains an organic compound.
[7] The ultrasonic mist according to any one of the above [1] to [6], wherein the film-forming raw material contains a cyclic organic compound.
[8] The ultrasonic mist according to any one of the above [1] to [7], wherein the boiling point of the first solvent is 180 ° C. or lower.
[9] The ultrasonic mist according to any one of the above [1] to [8], wherein the first solvent is an aromatic solvent.
[10] The ultrasonic mist according to any one of the above [1] to [9], wherein the boiling point of the second solvent is 200 ° C. or higher.
[11] The ultrasonic mist according to any one of the above [1] to [10], wherein the second solvent is an aprotic polar solvent.
[12] A method for forming a film on a substrate using a mist containing a film-forming raw material, wherein the ultrasonic mist according to any one of [1] to [11] is used as the mist. Film formation method.
[13] The film formation is carried out by transporting the mist to the substrate using a carrier gas, and then reacting the mist on the substrate to form a film on the substrate [12]. ] The film forming method described.

The ultrasonic mist of the present invention has the effect of being able to form a high-quality film in an industrially advantageous manner.

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-visible absorption measurement in an Example. It is a figure which shows the measurement result of the IV characteristic in an Example.

The ultrasonic mist of the present invention is an ultrasonic mist containing at least a film-forming raw material and two or more kinds of solvents, and the solvent has a boiling point and a viscosity at 25 ° C. higher than those of the first solvent and the first solvent. It is characterized by containing a high second solvent so that the volume ratio of the first solvent to the second solvent is 5: 1 to 1: 1.

The film-forming raw material is not particularly limited as long as it can be atomized by ultrasonic waves. It may contain an organic compound, or may contain an inorganic substance such as a metal or a metal compound. In the present invention, it is preferable that the film forming raw material contains an organic compound. The organic compound 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, anthracene, acenaphsen, acenaphthylene, benzopyrene, benzofluorene, benzophenanthrene and benzofluoroanisen. , Benzoperylene, Coronen, Chrysene, Hexabenzoperylene, Phthalocyanin, Perylene, Perinone, Anthraquinone, Kinacridone, Kinacridonquinone, Dioxazine, Indigo, Thioindigo, Pyranthron, Anthracene, Flavanthron, Indanceron, Isoindrinone, Kinophthalone or Fulleren And so on. Examples of the monocyclic organic compound include benzene, toluene, xylene, phenol, alkylphenol, resorcin, diphenyl, diphenyl ether, alkylbenzene, thiophene, furan, pyrrole, imidazole, pyrazole, isothiazole, isoxazole, pyridine, pyrazine and pyrimidine. Or Kumen 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 fullerene.

The fullerene is not particularly limited as long as it does not impair the object of the present invention, and may be a chemically modified fullerene derivative or a chemically modified fullerene, but in the present invention, the fullerene is chemically modified. It is preferable that the fullerene is not used. 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 blending ratio of the film-forming raw material in the ultrasonic mist 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 first solvent can be used as a solvent and is not particularly limited as long as it has a boiling point and a viscosity at 25 ° C. lower than those of the second solvent. It may be an inorganic solvent such as water or an organic solvent. More specifically, the water includes pure water, ultrapure water, tap water, well water mineral spring water, mineral water, hot spring water, spring water, fresh water, seawater and the like. More specifically, examples of the organic solvent include aromatic solvents, ether solvents, chain amide solvents, chain carbonate ester solvents, chain carbamate esters, carbonate solvents and the like. Examples of the aromatic solvent include toluene, xylene, trimethylbenzene chain carboxylic acid ester solvent, ethylbenzene, ethyltoluene, ethylxylenes, diethylbenzenes, alkylbenzenes such as propylbenzenes, and methylnaphthalene. , Ethylnaphthalene, alkylnaphthalene such as dimethylnaphthalene, other alkylbiphenyls, alkylanthranes, alkylbiphenyl ether and the like. Examples of the ether-based solvent include alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether; ethylene glycol monomethyl. Alkyl ether acetates of polyhydric alcohols such as ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate; diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, di Adipose ethers such as isoamyl ether, hexylmethyl ether, octylmethyl ether, cyclopentylmethyl ether, dicyclopentyl ether; aliphatic-aromatic ethers such as anisole and phenylethyl ether; cyclic ethers such as tetrahydrofuran, tetrahydropyran and dioxane. Kind and the like. Examples of the chain amide solvent include N, N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, N, N-diethylacetamide, N-methylpropionamide, and methylimidazolidinone. Can be mentioned. Examples of the chain carbonate ester solvent include dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, methylpropyl carbonate and the like. Examples of the chain carboxylic acid ester solvent include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate and the like. Examples of the chain carbamate ester include methyl N, N-diethylcarbamate, ethyl N, N-diethylcarbamate and the like. Examples of the carbonate-based solvent include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, dipropyl carbonate, methyl butyl carbonate, dibutyl carbonate and the like. In the present invention, the second solvent is preferably an aromatic solvent, more 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 viscosity of the first solvent at 25 ° C. is not particularly limited as long as it is lower than the viscosity of the second solvent at 25 ° C., but in the present invention, it is preferably 1.0 mPa · s or less. The lower limit of the viscosity of the first solvent at 25 ° C. is not particularly limited, but is preferably 0.5 mPa · s or more. The "viscosity" means the viscosity measured in accordance with JIS Z8803. Further, the boiling point of the first solvent is not particularly limited as long as it is lower than the boiling point of the second solvent. The boiling point of the first solvent is preferably 200 ° C. or lower, more preferably 180 ° C. or lower. Here, the boiling point means the boiling point under atmospheric pressure. Further, in the present invention, it is preferable that the solubility of the film-forming raw material in the first solvent at 25 ° C. is higher than the solubility of the film-forming raw material in the second solvent at 25 ° C. Here, the solubility means the mass (mg) of the film-forming raw material dissolved in 1.0 mL of the first solvent at 25 ° C. In the present invention, for convenience, the organic compound is added into 1.0 mL of the first solvent, and the amount of the film-forming raw material remaining at the time when the saturation concentration is reached or higher is subtracted from the amount of the film-forming raw material added. Can be measured. The solubility of the film-forming raw material in the first solvent at 25 ° C. is preferably 1.0 mg / mL or more, and more preferably 1.5 mg / mL or more.

The second solvent can be used as a solvent and is not particularly limited as long as it has a boiling point and a viscosity at 25 ° C. higher than those of the first solvent. In the present invention, the second solvent is preferably an organic solvent, more preferably an aprotic polar solvent. Examples of the aprotonic polar solvent include one or more solvents selected from a lactam solvent, a lactone solvent, a sulfoxide solvent, an organic phosphorus solvent, a glycol solvent, and a cellosolve solvent. Be done. Examples of the lactam solvent include N-methyl-pyrrolidone, 2-pyrrolidone, N-methylcaprolactam and the like. Examples of the lactone-based solvent include lactones such as β-lactones, γ-lactones, δ-lactones, and ε-lactones, and specific examples thereof include γ-butyrolactone and γ-valerolactone. , Ί-caprolactone, γ-caprylolactone, γ-laurolactone and the like, δ-lactone such as δ-valerolactone, ε-lactone such as ε-caprolactone and the like. Examples of the sulfoxide solvent include dimethyl sulfoxide, diethyl sulfoxide, methylphenyl sulfoxide, tetramethylene sulfoxide and the like. Examples of the organophosphorus solvent include tetramethylphosphoric amide and hexamethylphosphoric amide. Examples of the glycol-based solvent include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and the like. Examples of the cellosolve-based solvent include ethyl cellosolve acetate and methyl cellosolve acetate. In the present invention, the second solvent is preferably a lactam solvent, more preferably 2-pyrrolidone.

The viscosity of the second solvent at 25 ° C. is not particularly limited as long as it is higher than the viscosity of the first solvent at 25 ° C., but in the present invention, it is preferably 1.5 mPa · s or more, preferably 3.0 mPa. -S or more is more preferable, and 5.0 mPa · s or more is most preferable. The "viscosity" means the viscosity measured in accordance with JIS Z8803. The boiling point of the second solvent is not particularly limited as long as it is higher than the boiling point of the first solvent, but in the present invention, it is preferably 180 ° C. or higher, and more preferably 200 ° C. or higher. Here, the boiling point means the boiling point under atmospheric pressure. Further, the solubility of the film-forming raw material in a second solvent at 25 ° C. is preferably less than 1.0 mg / mL. Here, the solubility means the mass (mg) of the film-forming raw material dissolved in 1.0 mL of the second solvent at 25 ° C. In the present invention, for convenience, the film-forming raw material is put into 1.0 mL of the second solvent, and the amount of the organic compound remaining when the saturation concentration is reached or higher is subtracted from the amount of the film-forming raw material added. Can be measured.

The mixing ratio of the first solvent in the ultrasonic mist is not particularly limited, but is preferably 0.0001 mol% to 90 mol%, more preferably 0.001 mol% to 50 mol%. The mixing ratio of the second solvent in the ultrasonic mist is not particularly limited, but is preferably 0.01 mol% to 99 mol%, and more preferably 1 mol% to 95 mol%. In the present invention, the volume ratio of the first solvent to the second solvent in the ultrasonic mist is not particularly limited as long as it is 5: 1 to 1: 1, but in the present invention, it is better and better. Since the film can be stably formed, it is preferably 5: 1 to 2: 1 and most preferably 4: 1 to 7: 3.

The ultrasonic mist may further contain additives. The additive is not particularly limited as long as it does not impair 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, hypophosphite, or 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 aprotic polar solvent or the aromatic non-polar solvent, or may be 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 specifically, 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 ultrasonic mist is obtained by atomizing a solution obtained by mixing at least the film-forming raw material, the first solvent, and the second solvent by using ultrasonic vibration. The mixing means is not particularly limited and may be a known mixing means. The frequency of the ultrasonic vibration is not particularly limited, but in the present invention, it is preferably 0.1 MHz to 5.0 MHz, and more preferably 1.0 MHz to 5.0 MHz. The particle size of the ultrasonic mist is not particularly limited and may be about several mm, but is preferably 50 μm or less, and more preferably 100 nm to 10 μm.

By using the ultrasonic mist of the present invention, it is possible to form a high-quality film with high film-forming quality and industrially advantageous. More specifically, for example, a film can be formed from the ultrasonic mist directly on the substrate or via another layer by using a known film forming means. The film forming means is not particularly limited, but in the present invention, the mist CVD method is preferable, and more specifically, the ultrasonic mist is conveyed onto the substrate by a carrier gas (conveyance step) and then onto the substrate. Examples thereof include a method of reacting the ultrasonic mist with the above-mentioned material to form a film on the substrate (film-forming step). Hereinafter, such a preferable film forming method will be described in more detail.

(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 impair 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 suitably used as the substrate. The constituent metal of the metal film is, for example, one selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium and barium. 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 selenium, metal nitride 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 materials 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 phase growth 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 coat, brush coating, spray coating, roll coater, air knife coat, curtain coat, wire bar coat, gravure coat, 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.

(Transport process)
In the transfer step, the ultrasonic mist is conveyed to the substrate by the 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 place but also at two or more places. 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 0.001 to 2 L / min, more preferably 0.1 to 1 L / min.

(Film formation process)
In the film forming step, the ultrasonic mist is reacted on the substrate to form a film on the substrate. The reaction may be a physical reaction or a chemical reaction as long as the ultrasonic mist reacts. The reaction may be a reaction by drying, but a thermal reaction by heat is preferable, and the thermal reaction may be any reaction as long as the ultrasonic mist reacts by heat, 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 usually carried out at 300 ° C. or lower, 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 vacuum, non-oxygen atmosphere, reducing gas atmosphere and 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 done 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 a film 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 a film as described above, it is possible to form a film with high film formation quality and industrially advantageous. Further, the film thickness of the obtained film can be easily adjusted by adjusting the film forming time.

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

(Example 1)
1. 1. Film forming apparatus The film forming apparatus 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. The container 5 in which the 5a is placed, the ultrasonic transducer 6 attached to the bottom surface of the container 5, the hot plate 8, the substrate 10 mounted on the hot plate 8, and the mist source 4 to the vicinity of the substrate 10. It is provided with a supply pipe 9 for connecting the gas.

2. 2. Preparation of raw material solution C60 fullerene was mesitylene (viscosity: about 1.0 mPa · s, solubility of C60 fullerene at 25 ° C: 1.5 mg / mL) and 2-pyrrolidone (viscosity: about 13.3 mPa · s, C60 at 25 ° C). The solubility of fullerene: about 0 mg / mL) was mixed, and this was used as a raw material solution. 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) was housed in the mist generation 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 that of the carrier gas (diluted) supplied from the carrier gas (diluted) 2b. 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 at 210 ° C. under atmospheric pressure to form a fullerene film on the substrate 10. 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 results are 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 results are 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 measured for ultraviolet absorption in the same manner as in Example 1. The results are 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)
As Examples 9 to 12, fullerenes are the same as in Examples 1 to 4, except that the mixing ratio of mesitylene and 2-pyrrolidone in 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)
The 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 the film could not be formed.

By using the ultrasonic mist of the present invention, it is possible to form an industrially advantageous film with high film forming quality, and in particular, it is possible to form a film at low temperature, atmospheric pressure and non-vacuum, so that there are restrictions on the substrate and the like. It can be used in a wide variety of fields. Further, the film obtained by using the ultrasonic mist of the present invention can be suitably used for, for example, a photoelectric conversion device.

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 oscillator 8 Hot plate 9 Supply pipe 10 Substrate

Claims (9)

An ultrasonic mist containing at least a film-forming raw material and two or more kinds of solvents, wherein the solvent has an aromatic solvent as a first solvent and a boiling point and a viscosity at 25 ° C. higher than those of the first solvent. and aprotic polar solvents as second solvent, the volume ratio of the first solvent and the second solvent is from 5: 1 to 1: 1 so as to look including the film forming material is a cyclic organic compound An ultrasonic mist characterized by being. The ultrasonic mist according to claim 1, wherein the viscosity of the first solvent at 25 ° C. is 1.0 mPa · s or less. The ultrasonic mist according to claim 1 or 2, wherein the viscosity of the second solvent at 25 ° C. is 1.5 mPa · s or more. The ultrasonic mist according to any one of claims 1 to 3, wherein the solubility of the film-forming raw material in a first solvent at 25 ° C. is higher than the solubility of the film-forming raw material in a second solvent at 25 ° C. The ultrasonic mist according to any one of claims 1 to 4, wherein the volume ratio of the first solvent to the second solvent is 4: 1 to 7: 3. The ultrasonic mist according to any one of claims 1 to 5 , wherein the boiling point of the first solvent is 180 ° C. or lower. The ultrasonic mist according to any one of claims 1 to 6 , wherein the boiling point of the second solvent is 200 ° C. or higher. A method for forming a film on a substrate using a mist containing a film-forming raw material, wherein the ultrasonic mist according to any one of claims 1 to 7 is used as the mist. The deposition, the mist is conveyed up on the substrate using a carrier gas, then the by reacting the mist on a substrate, formed of claim 8, wherein performing by forming a film on the substrate Membrane method.

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