JP2011046566A - Composition for producing doped zinc oxide thin film, and method for producing doped zinc oxide thin film using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for producing a zinc oxide thin film, which uses an organic zinc compound as a starting material, is not ignitable, and can be easily handled, and which can form a transparent zinc oxide thin film doped with a group 3B element by being heated at ≤300°C, and to provide a method for obtaining a transparent zinc oxide thin film doped with a group 3B element using the composition. <P>SOLUTION: The composition for producing a doped zinc oxide thin film contains a product which is obtained by partially hydrolyzing an organic zinc compound by adding water to a solution of the organic zinc compound and a group 3B element compound, wherein the molar ratio of the group 3B element compound to the organic zinc compound is within the range of 0.005-0.3. The composition for producing a doped zinc oxide thin film contains a product which is obtained by partially hydrolyzing an organic zinc compound by adding water to a solution of the organic zinc compound and then adding a group 3B element compound so that the molar ratio of the group 3B element compound to the organic zinc compound is within the range of 0.005-0.3. The method for forming a zinc oxide thin film doped with a group 3B element includes applying the composition on the surface of a substrate and heating the applied composition. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composition for producing a zinc oxide thin film doped with a group 3B element, which is prepared using an organic zinc compound as a raw material and is easy to handle, and a zinc oxide thin film doped with a group 3B element using the composition. It relates to a manufacturing method. In particular, the present invention is doped with a group 3B element capable of forming a transparent zinc oxide thin film having a high transmittance for visible light by heating at a temperature of about 300 ° C. or less under a pressure near atmospheric pressure. The present invention relates to a composition for producing a zinc oxide thin film and a method for producing a zinc oxide thin film doped with a group 3B element using this composition.

  A zinc oxide thin film doped with a transparent group 3B element having high transparency to visible light is composed of a photocatalyst film, an ultraviolet cut film, an infrared reflective film, a buffer layer for CIGS solar cells, and an electrode film for dye-sensitized solar cells. It is used for antistatic films and has a wide range of uses.

  Various methods are known as a method for producing a transparent zinc oxide thin film doped with a group 3B element (Non-patent Document 1). As a typical method using an organic zinc compound as a raw material, a chemical vapor deposition (CVD) method (Non-Patent Document 2), a spray pyrolysis method (Non-Patent Document 3), a spin coating method (Patent Document 1), There are coating methods such as a dip coating method (Non-patent Document 4).

  However, the chemical vapor deposition (CVD) method requires the use of a large vacuum container and the film forming speed is very slow, resulting in an increase in manufacturing cost. Moreover, since the size of the zinc oxide thin film doped with the group 3B element, which can be formed depending on the size of the vacuum vessel, is limited, there is a problem that a large size cannot be formed.

  Compared with the chemical vapor deposition (CVD) method, the coating method is simpler and has a higher film formation speed, and therefore has higher productivity and lower manufacturing costs. Moreover, since there is no need to use a vacuum vessel and there are no restrictions due to the vacuum vessel, there is an advantage that a zinc oxide thin film doped with a large group 3B element can be produced.

  In the spray pyrolysis method, solvent drying is performed simultaneously with spray coating, and then the substrate temperature is heated to 360 ° C. or higher to obtain a zinc oxide thin film coated with a group 3B element.

  In the above spin coating method and dip coating method, the solvent is dried after spin coating or dip coating, and then the substrate temperature is heated to 400 ° C. or higher to obtain a zinc oxide thin film coated with a group 3B element.

JP 7-182939 A

Japan Society for the Promotion of Science Transparent Oxide Optoelectronic Materials 166th Committee, Transparent Conductive Film Technology Revision 2 (2006), p165-173 K. Sorab, et al. Appl. Phys. Lett., 37 (5), 1 September 1980 F. Paraguay D, et al. Thin Solid films., 16 (366), 2000 Y. Ohya, et al. J. Mater. Sci., 4099 (29), 1994

  A transparent zinc oxide thin film doped with a group 3B element has been formed on a plastic substrate. Therefore, it is necessary that the heating applied at the time of forming the transparent zinc oxide thin film doped with the group 3B element be performed at a temperature lower than the heat resistance temperature of the plastic substrate. However, in the spray pyrolysis method described in Non-Patent Document 3, the spin-coating method described in Patent Document 1, and the dip-coating method described in Non-Patent Document 4, the heat resistance temperature of the plastic substrate (usually, the material is also used). However, heating at a temperature of about 300 to 400 ° C. or less cannot obtain a transparent zinc oxide thin film doped with a group 3B element. Considering the heat-resistant temperature of the plastic substrate and the cost required for heating, it is desirable that the heating required for film formation is 300 ° C. or lower.

  The present inventors have prepared an aqueous solution of a group 3B element compound and zinc acetate used in the spray pyrolysis method described in Non-Patent Document 3, and a group 3B element compound used in the spin coating method described in Patent Document 1. Furthermore, a film is formed at a temperature of 300 ° C. or lower using a solution composed of an organic zinc compound and an organic solvent or a solution composed of an organic zinc compound and an organic solvent used in the dip coating method described in Non-Patent Document 4. Tried. However, in any case, a transparent zinc oxide thin film doped with a group 3B element was not obtained, and only an opaque zinc oxide thin film was obtained. Even when the hexane solution of diethyl zinc described in Patent Document 1 was used, film formation at 300 ° C. or lower was attempted. However, similarly, a transparent zinc oxide thin film doped with a group 3B element was not obtained.

  Diethylzinc is a compound that is ignitable in the atmosphere and must be very carefully stored and used. For this reason, it is practically difficult to use it in a spray pyrolysis method, spin coating method, etc., which is often performed in an atmosphere containing water without diluting diethyl zinc. On the other hand, diethyl zinc can reduce risks such as ignition when dissolved in an organic solvent. As described in Patent Document 1, the risk can be reduced in the formation of a zinc oxide thin film using diethyl zinc dissolved while reacting with an alcohol-based organic solvent. It was necessary to heat at a high temperature.

  Therefore, the object of the present invention is to prepare an organozinc compound as a raw material, but it is easy to handle because it is not ignitable, and even if heating is required, a transparent Group 3B element can be obtained by heating at 300 ° C. or lower. It is to provide a composition for producing a zinc oxide thin film capable of forming a doped zinc oxide thin film. Further, the object of the present invention is to take into consideration the heat resistance temperature of plastic substrates and the cost required for heating, etc., using this composition. Then, it is providing the method of obtaining the zinc oxide thin film by which the transparent 3B group element was doped.

The present invention for solving the above problems is as follows.
[1]
An organic zinc compound represented by the following general formula (1) and at least one of group 3B element compounds represented by the following general formula (2) or the following general formula (3) were dissolved in an electron-donating organic solvent. A solution obtained by adding water to the solution and at least partially hydrolyzing the organozinc compound, wherein the 3B group element compound has a molar ratio of 0.005 to 0 with respect to the organozinc compound. A composition for producing a doped zinc oxide thin film having a ratio of .3.
R ¹ —Zn—R ¹ (1)
(In the formula, R ¹ is a linear or branched alkyl group having 1 to 7 carbon atoms)
M _c X _d · aH ₂ O (2)
(Wherein M is a group 3B element, X is a halogen atom, nitric acid or sulfuric acid, c is 1, when d is a halogen atom or nitric acid, d is 3, and when X is sulfuric acid, c is 2 D is 3, and a is an integer of 0 to 9.)
R ² -M-R ³
| (L) _n (3)
R ⁴
(In the formula, M is a group 3B element, R ² , R ³ , and R ⁴ are independently hydrogen, a linear or branched alkyl group having 1 to 7 carbon atoms, or a linear or branched group having 1 to 7 carbon atoms. An alkoxyl group, a carboxylic acid group, or an acetylacetonate group, L is a coordinating organic compound containing nitrogen, oxygen or phosphorus, and n is an integer of 0 to 9.)
[2]
The composition according to [1], wherein the product includes a hydrolyzate of the group 3B element compound.
[3]
The composition according to [1] or [2], wherein the water is added in a molar ratio of 0.4 to 0.9 with respect to the total amount of the organozinc compound and the group 3B element compound.
[4]
Water is added to a solution in which the organozinc compound represented by the general formula (1) is dissolved in an electron-donating organic solvent to hydrolyze the organozinc compound at least partially, and then the general formula (2) or A product obtained by adding at least one group 3B element compound represented by the general formula (3) such that the molar ratio to the organozinc compound is 0.005 to 0.3; A composition for producing a doped zinc oxide thin film.
R ¹ —Zn—R ¹ (1)
(In the formula, R ¹ is a linear or branched alkyl group having 1 to 7 carbon atoms)
M _c X _d · aH ₂ O (2)
(Wherein M is a group 3B element, X is a halogen atom, nitric acid or sulfuric acid, c is 1, when d is a halogen atom or nitric acid, d is 3, and when X is sulfuric acid, c is 2 D is 3, and a is an integer of 0 to 9.)
R ² -M-R ³
| (L) _n (3)
R ⁴
(In the formula, M is a group 3B element, R ² , R ³ , and R ⁴ are independently hydrogen, a linear or branched alkyl group having 1 to 7 carbon atoms, or a linear or branched group having 1 to 7 carbon atoms. An alkoxyl group, a carboxylic acid group, or an acetylacetonate group, L is a coordinating organic compound containing nitrogen, oxygen or phosphorus, and n is an integer of 0 to 9.)
[5]
The composition according to [4], wherein the product does not substantially contain a hydrolyzate of the group 3B element compound.
[6]
The amount of water added is the composition according to [4] or [5], wherein the molar ratio with respect to the organozinc compound is in the range of 0.4 to 0.9.
[7]
The said composition is a composition in any one of [1]-[6] whose content of the organic zinc compound represented by General formula (1) is 0.5 wt% or less.
[8]
The composition according to any one of [1] to [7], comprising a solution obtained by dissolving the product in a thin film forming organic solvent different from the electron donating organic solvent.
[9]
The composition according to any one of [1] to [8], wherein the concentration of the product is in the range of 1 to 30% by mass.
[10]
The composition according to any one of [1] to [9], wherein the organic zinc compound is a compound in which R ¹ is an alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms.
[11]
The composition according to any one of [1] to [10], wherein the organozinc compound is diethyl zinc.
[12]
The composition according to any one of [1] to [11], wherein the electron-donating organic solvent is 1,4-dioxane.
[13]
The composition according to any one of [1] to [12] is applied to a substrate surface, and then the obtained coating film is heated at a temperature of 300 ° C. or lower to form a zinc oxide thin film doped with a group 3B element. A method for producing a doped zinc oxide thin film, comprising forming.
[14]
The said doped zinc oxide thin film is a manufacturing method as described in [13] which has an average transmittance | permeability of 80% or more with respect to visible light.

  The composition for producing a zinc oxide thin film doped with a group 3B element of the present invention is not ignitable and easy to handle, and when the composition for producing a zinc oxide thin film doped with a group 3B element of the present invention is used, A transparent zinc oxide thin film doped with a group 3B element can be produced even if the film is formed at a temperature of ℃ or less.

NMR spectrum after vacuum drying of the composition obtained in Example 1 XRD spectrum of the aluminum-doped zinc oxide thin film obtained in Example 1 NMR spectrum after vacuum drying of the composition obtained in Example 2 XRD spectrum of the gallium-doped zinc oxide thin film obtained in Example 2 NMR spectrum after vacuum drying of the composition obtained in Example 3 XRD spectrum of the indium-doped zinc oxide thin film obtained in Example 3

[Composition for producing zinc oxide thin film doped with group 3B element]
The composition for producing a zinc oxide thin film doped with a group 3B element of the present invention comprises (i) an organozinc compound represented by the following general formula (1) and 3B represented by the following general formula (2) or (3). A product obtained by adding water to a solution in which at least one group element compound is dissolved in an electron-donating organic solvent and at least partially hydrolyzing the organic zinc compound (hereinafter, partial hydrolysis) Or (ii) water added to a solution in which the organic zinc compound represented by the general formula (1) is dissolved in an electron-donating organic solvent, and the organic zinc After the compound is at least partially hydrolyzed, a product obtained by adding at least one group 3B element compound represented by the general formula (2) or (3) (hereinafter referred to as partial hydrolyzate 2 and May be called).
R ¹ —Zn—R ¹ (1)
(In the formula, R ¹ is a linear or branched alkyl group having 1 to 7 carbon atoms)
M _c X _d · aH ₂ O (2)
(Wherein M is a group 3B element, X is a halogen atom, nitric acid or sulfuric acid, c is 1, when d is a halogen atom or nitric acid, d is 3, and when X is sulfuric acid, c is 2 D is 3, and a is an integer of 0 to 9.)
R ² -M-R ³
| (L) b (3)
R ⁴
(In the formula, M is a group 3B element, R ² , R ³ , and R ⁴ are independently hydrogen, a linear or branched alkyl group having 1 to 7 carbon atoms, or a linear or branched group having 1 to 7 carbon atoms. And L is a coordinating organic compound containing any one of nitrogen, oxygen and phosphorus, and b is an integer of 0 to 9.)

  In the partial hydrolyzate 1, water is added to the mixed solution of the organozinc compound and the group 3B element compound, so that the product usually contains a hydrolyzate of the group 3B element compound. The hydrolyzate of the group 3B element compound may be a partial hydrolyzate depending on the amount of water added. Further, in the partially hydrolyzed product 2, since the group 3B element compound is added after adding water to the organic zinc compound, depending on the amount of water added, the added water is consumed for hydrolysis of the organic zinc compound. When the group 3B element compound is added after the formation, the product usually does not contain the hydrolyzate of the group 3B element compound. The group 3B element compound is not hydrolyzed and is contained as a raw material, or the organic group of the partial hydrolyzate of the organozinc compound and the organic group (ligand) of the group 3B element compound are exchanged ( Ligand exchange) may also occur.

  In the partial hydrolyzate 1, the amount of water added is such that the molar ratio with respect to the total amount of the organozinc compound and the group 3B element compound is in the range of 0.4 to 0.9. Moreover, in the partial hydrolyzate 2, the addition amount of the water makes the molar ratio with respect to the said organic zinc compound into the range of 0.4-0.9.

  It is preferable to limit the total amount of the organic zinc compound and the organic 3B group element compound, or the addition molar ratio of water to the organic zinc compound in the range of 0.4 to 0.9. By setting the molar ratio to 0.4 or more, an organic zinc composition containing a product obtained by partially hydrolyzing an organic zinc compound with a high yield of 90% or more based on zinc contained in the raw material can be obtained. . In the partial hydrolyzate 1, an appropriate amount of the Group 3B element compound is also partially hydrolyzed. By making the molar ratio 0.4 or more, in the case of the partial hydrolyzate 1, the organozinc compound and the 3B group element compound which are unreacted raw materials, and in the case of the partial hydrolyzate 2, the organozinc compound remains. The amount can be reduced, and as a result, an organic zinc composition that can be handled safely can be obtained. Moreover, generation | occurrence | production of the gel during a hydrolysis reaction can be suppressed by making molar ratio into 0.9 or less. When gel is generated during the hydrolysis reaction, the viscosity of the solution increases, and the subsequent operation may be difficult. The addition molar ratio of water is preferably in the range of 0.6 to 0.8, more preferably in the range of 0.6 to 0.75.

  The electron-donating organic solvent may be an organic zinc compound represented by the general formula (1), a group 3B element compound represented by the general formula (2) or (3), and water. Well, examples include ether solvents such as diethyl ether, di-n-propyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dioxane, glyme, diglyme and triglyme, and amine solvents such as trimethylamine, triethylamine and triphenylamine. be able to. As the electron-donating solvent, tetrahydrofuran and dioxane are preferable.

Specific examples of the alkyl group represented by R ¹ in the organozinc compound represented by the general formula (1) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a sec-butyl group. Tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, 2-hexyl group, and heptyl group. In the compound represented by the general formula (1), R ¹ is preferably a compound having 1, 2, 3, 4, 5, or 6 carbon atoms. The compound represented by the general formula (1) is preferably diethyl zinc, in which R ¹ has 2 carbon atoms.

  Specific examples of the metal represented by M in the 3B group element compound represented by the general formula (2) include B, Al, Ga, and In. Specific examples of the salt represented by X include fluorine, chlorine, bromine, iodine, nitric acid, sulfuric acid, and phosphoric acid. The group 3B element compound represented by the general formula (2) includes, in particular, boron chloride, aluminum chloride hexahydrate, aluminum nitrate nonahydrate, gallium chloride, gallium nitrate hydrate, indium chloride tetrahydrate, Mention may be made of indium nitrate pentahydrate.

Specific examples of the metal represented by M in the group 3B element compound represented by the general formula (3) include B, Al, Ga, and In. R ² , R ³ and R ⁴ are preferably hydrogen. Alternatively, R ² , R ³ , and R ⁴ are preferably alkyl groups. Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a sec-butyl group. Tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, 2-hexyl group, and heptyl group. It is also preferred that at least one of R ² , R ³ and R ⁴ is hydrogen and the rest is an alkyl group. Examples of the ligand represented by L include trimethylamine, triethylamine, triphenylamine, pyridine, monofoline, N, N-dimethylaniline, N, N-diethylaniline, triphenylphosphine, dimethylsulfur, diethyl ether, and tetrahydrofuran. be able to. The group 3B element compound represented by the general formula (3) includes, in particular, diborane, borane-tetrahydrofuran complex, borane-trimethylamine complex, borane-triethylamine complex, triethylborane, tributylborane, alane-trimethylamine complex, alane-triethylamine complex, Mention may be made of trimethylaluminum, dimethylamylnium hydride, triisobutylaluminum, diisobutylaluminum hydride, trimethylgallium, triethylgallium, trimethylindium, trimethylindium and triethylindium. Triethylaluminum, triisobutylaluminum, trimethylgallium, and trimethylindium are particularly preferable because they are inexpensive and easily available.

  In the composition of the present invention, the molar ratio of the group 3B element compound represented by the general formula (2) or (3) to the organozinc compound and the organozinc compound represented by the general formula (1) is 0.00. Add at a rate of 005 to 0.3. If the added amount of the group 3B element compound is too large, the film characteristics tend to be deteriorated as impurities, and therefore the ratio is preferably 0.005 to 0.1. However, in the partial hydrolyzate 1, water is added to the solution containing the organic zinc compound and the 3B group element compound at the molar ratio to obtain a partial hydrolyzate. Moreover, in the partial hydrolyzate 2, water is added to the solution containing an organozinc compound, a partial hydrolyzate is obtained, and the 3B group element compound is added by the said molar ratio on it.

  In the general formula (1) in a solution obtained by dissolving the compound represented by the general formula (1) and the group 3B element compound represented by the general formula (2) or (3) in the electron donating organic solvent. The total concentration of the compound represented by the general formula (2) or (3) and the concentration of the compound represented by the general formula (2) or (3) is appropriately determined in consideration of solubility in a solvent. The range of 1 to 50% by mass is appropriate.

  When at least partially hydrolyzing the organozinc compound of the general formula (1) and then adding the 3B element compound of the general formula (2) or (3), the compound represented by the general formula (1) The concentration of the compound represented by the general formula (1) in the solution dissolved in the electron-donating organic solvent is appropriately determined in consideration of the solubility in the solvent and the like. % Range is appropriate.

  The addition of water can be performed without mixing water with another solvent or after mixing water with another solvent. The addition of water can be performed, for example, over a time period of 60 seconds to 10 hours, depending on the scale of the reaction. From the viewpoint that the yield of the product is good, it is preferable to add it by dropping water into the organozinc compound of the general formula (1) as a raw material. The addition of water can be carried out without stirring (while standing) or stirring the solution of the compound represented by the general formula (1) and the electron donating organic solvent. The temperature at the time of addition can select arbitrary temperature between -90-150 degreeC. It is preferable that it is -15-30 degreeC from a viewpoint of the reactivity of water and an organic zinc compound.

  Reaction of water and the compound represented by general formula (1) and the compound represented by general formula (2) or (3), or water and the compound represented by general formula (1) after addition of water For example, leave for 1 minute to 48 hours without stirring (still standing) or stir. About reaction temperature, it can be made to react at arbitrary temperature between -90-150 degreeC. It is preferable that it is 5-80 degreeC from a viewpoint of obtaining a partial hydrolyzate with a high yield. The reaction pressure is not limited. Usually, it can be carried out at normal pressure (atmospheric pressure). The progress of the reaction between water and the compound represented by the general formula (1) is monitored by sampling the reaction mixture, analyzing the sample by NMR or IR, or sampling the generated gas, if necessary. Can do.

  The organic solvent, the organic zinc compound of the general formula (1) as a raw material, and water can be introduced into the reaction vessel according to any conventional method, and can also be introduced as a mixture with the solvent. These reaction steps may be a batch operation method, a semi-batch operation method, or a continuous operation method, and are not particularly limited, but a batch operation method is desirable.

By the above reaction, the organozinc compound of the general formula (1) and the group 3B element compound of the general formula (2) or (3), or the organozinc compound of the general formula (1) are at least partially in water. To obtain a product containing a partial hydrolyzate. When the organozinc compound of the general formula (1) is diethyl zinc, the analysis of the product obtained by reaction with water has been conducted for a long time, but the results differ depending on the report, and the composition of the product is clearly It is not specified. Further, the composition of the product can be changed depending on the molar ratio of water, the reaction time, and the like. In the present invention, the main component of the product includes, for the partial hydrolyzate 1, structural units represented by the following general formulas (4) and (5) and structural units represented by the following general formula (6). It is a combined compound or a mixture of a plurality of compounds with different m.
(R ₁ -Zn)-(4)
-[O-Zn] _m- (5)
(In the formula, R ¹ is the same as R ¹ in the general formula (1), m is an integer from 2 to 20.)
-[OM]-
| (6)
Q
(In the formula, M is the same as M in the general formula (2) or (3), and Q is the same as any one of X, R ² , R ³ and R ^{4 in} the general formula (2) or (3). , M is an integer from 2 to 20.)

The partial hydrolyzate 2 is presumed to be a compound represented by the following general formula (8) or a mixture of plural kinds of compounds having different m.
R ¹ —Zn— [O—Zn] _p —R ¹ (8)
(In the formula, R ¹ is the same as R ¹ in the general formula (1), p is an integer from 2 to 20.)

  When the organic zinc compound is hydrolyzed, if the 3B group element compound is not present, a composition is produced by adding the 3B group compound of the general formula (2) or (3) after the reaction is completed. To do. The addition amount of the 3B group element compound is 0.005 to 0.3 with respect to the charged amount of the organic zinc compound. From the viewpoint of ensuring the effect of addition of the group 3B element compound, and when the addition amount increases, the film characteristics tend to be deteriorated as impurities, so 0.005 to 0.1 is particularly preferable.

  After completion of the hydrolysis reaction, a part or all of the product can be recovered and purified by a general method such as filtration, concentration, extraction, column chromatography and the like. Moreover, when adding a 3B group element compound after completion | finish of a hydrolysis reaction, a part or all of the said product can be collect | recovered and refine | purified by filtration. When the organozinc compound of the general formula (1), which is a raw material, remains in the reaction product, it can be recovered by the above method and is preferably recovered. It is preferable that the reaction product after recovering the raw material remaining by these methods does not contain the organic zinc compound represented by the general formula (1), for example, represented by the general formula (1). The content of the organozinc compound is preferably 0.5 wt% or less. From the viewpoint that the composition of the present invention does not contain the organic zinc compound represented by the general formula (1) which remains unreacted and is used as a coating solution, a uniform film is formed. preferable.

  The composition separated and recovered from the electron donating organic solvent by the above method can be dissolved in a thin film forming organic solvent different from the electron donating organic solvent used in the reaction to form a coating solution. In addition, the reaction product mixture can be used as it is or without any separation of the electron-donating organic solvent, or the concentration can be adjusted appropriately to obtain a coating solution.

  The organic solvent for forming a thin film, which is different from the electron donating organic solvent used in the reaction, is preferably a solvent having a boiling point of 85 ° C. or higher, for example. This is because, since the boiling point is relatively high, the volatility is low, and deterioration of workability due to evaporation of the solvent and drying of the coating film during the application work can be avoided.

  Examples of the organic solvent for forming the thin film include aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane and petroleum ether, aromatic hydrocarbon solvents such as benzene, toluene, ethylbenzene and xylene, diethyl ether and diisopropyl. Examples include ether solvents such as ether, glyme, diglyme, triglyme, dioxane and tetrahydrofuran, and amine solvents such as trimethylamine, triethylamine and triphenylamine. These can be used not only alone but also in combination of two or more. Considering the solubility of the reaction product including the partial hydrolyzate of the organozinc compound contained in the reaction product and the volatility of the organic solvent itself, the organic solvent for forming a thin film is 1,4-dioxane. , Methyl monoglyme, ethyl monoglyme and methyldiglyme are preferred.

  The solid content concentration of the composition for forming a zinc oxide thin film can be arbitrarily selected within the range of 1 to 30% by mass. The higher the concentration, the smaller the number of coatings that can be produced, but considering the solubility of the reaction product containing the partial hydrolyzate of the organozinc compound and the ease of forming a transparent zinc oxide thin film, it is 1 to 12% by mass. Is preferred.

[Method for producing zinc oxide thin film]
The present invention relates to a method for producing a zinc oxide thin film. This manufacturing method includes applying the composition for forming a zinc oxide thin film of the present invention to the substrate surface, and then heating the obtained coating film at a temperature of 300 ° C. or lower to form a zinc oxide thin film.

  Application to the substrate surface can be carried out by conventional means such as dip coating, spin coating, spray pyrolysis, ink jet, and screen printing. The spray pyrolysis method is a method that can be performed while heating the substrate. Therefore, the solvent can be dried in parallel with the application, and depending on conditions, heating for drying the solvent may be unnecessary. Furthermore, depending on conditions, in addition to drying, the reaction of the partial hydrolyzate of the organozinc compound with zinc oxide may proceed at least partially. Therefore, the zinc oxide thin film can be formed more easily by heating at a predetermined temperature, which is a subsequent process. The heating temperature of the substrate in the spray pyrolysis method can be in the range of 50 to 250 ° C., for example.

  The composition is applied to the substrate surface under an inert gas atmosphere such as nitrogen, an air atmosphere, an air atmosphere containing a large amount of water vapor, a high relative humidity, an oxidizing gas atmosphere such as oxygen, or a reducing gas atmosphere such as hydrogen. Or under any atmosphere such as a mixed gas atmosphere thereof and at atmospheric pressure or under pressure. Since the product contained in the composition of the present invention reacts with moisture in the atmosphere and gradually decomposes, it is preferably carried out in an inert gas atmosphere containing no moisture. The coating in the method of the present invention can be carried out under reduced pressure, but it is preferable to carry out at atmospheric pressure because the apparatus is simple and convenient.

  After coating the coating liquid on the substrate surface, the substrate is brought to a predetermined temperature if necessary, the solvent is dried, and then heated at the predetermined temperature to form a zinc oxide thin film.

  The temperature at which the solvent is dried can be, for example, in the range of 20 to 200 ° C., and can be set as appropriate according to the type of the organic solvent that coexists. The heating temperature for forming zinc oxide after drying the solvent is, for example, in the range of 20 to 300 ° C, preferably in the range of 50 to 250 ° C, and more preferably in the range of 100 to 200 ° C. It is also possible to perform the solvent drying and the zinc oxide formation at the same time by making the solvent drying temperature the same as the heating temperature for the subsequent zinc oxide formation.

  If necessary, further promote the formation of zinc oxide by performing the above heating in an oxidizing gas atmosphere such as oxygen, a reducing gas atmosphere such as hydrogen, and a plasma atmosphere such as hydrogen, argon, oxygen, or the like, or It is also possible to improve crystallinity. Although there is no restriction | limiting in particular in the film thickness of a zinc oxide thin film, It is preferable that it is the range of 0.05-2 micrometers practically. According to the production method of the present invention, a thin film having a film thickness in the above range can be appropriately produced by repeating the application (drying) heating once or more.

  The zinc oxide thin film formed by the production method of the present invention preferably has an average transmittance of 80% or more with respect to visible light, and more preferably has an average transmittance of 85% or more with respect to visible light. Have. “Average transmittance for visible light” is defined and measured as follows. The average transmittance for visible light refers to the average of the transmittance of light in the range of 380 to 780 nm, and is measured by an ultraviolet-visible spectrophotometer. The average transmittance for visible light can also be expressed by presenting the visible light transmittance of 550 nm. The transmittance for visible light changes (increases) at the time of spray coating or depending on the degree of formation of zinc oxide by heating after coating, so that the transmittance of the thin film to visible light is considered to be 80% or more. It is preferable to set the heating conditions (temperature and time) at the time of application or after application.

  Furthermore, since the zinc oxide thin film formed by the manufacturing method of the present invention is doped with a group 3B element, the possibility of obtaining a low-resistance film increases by further devising the film forming method. .

  In the present invention, for example, a transparent base film can be used as the substrate, and the transparent base film can be a plastic film. Examples of the polymer forming the plastic film include polyester (for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), poly (meth) acrylic (for example, polymethylmethacrylate (PMMA)), and polycarbonate. Examples include (PC), polystyrene, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyethylene, cyclic polyolefin (COP), ethylene-vinyl acetate copolymer, polyurethane, triacetate, and cellophane. ET, PEN, PC and PMM A are preferred, and the transparent substrate film may be an unstretched film or a stretched film depending on the type of polymer, for example, a polyester film such as a PET film , Usually biaxial A Shin film, also P C film, triacetate film, cellophane film, etc. is usually a non-oriented film.

  EXAMPLES The present invention will be described in more detail with reference to examples below, but these examples do not limit the present invention. Preparation of a product containing a partial hydrolyzate from all organozinc compounds and film formation using the product were performed in a nitrogen gas atmosphere, and all solvents were used after dehydration and deaeration.

[Example 1]
1.91 g of diethylzinc was added to 30.0 g of 1,4-dioxane. After sufficiently stirring, it was cooled to 12 ° C. A 1,4-dioxane solution containing 5.0% water was added dropwise so that the molar ratio of water to diethylzinc was 0.6. Thereafter, the temperature was raised to room temperature (22 ° C.) and reacted at room temperature for 18 hours, and then added at a molar ratio of 0.02 to diethylzinc charged with triethylaluminum. The solution obtained as described above was filtered with a membrane filter to obtain 32.1 g of a partial hydrolyzate solution (concentration 5.6% by mass) containing aluminum. The spectrum of FIG. 1 was obtained by NMR (THF-d8, ppm) measurement after removing the solvent and the like by vacuum drying.

  The product-containing coating solution containing the partial hydrolyzate obtained as described above was applied onto the surface of an 18 mm square Corning 1737 glass substrate by spin coating. Thereafter, the substrate was heated at 120 ° C. for 4 minutes to dry the solvent and simultaneously form zinc oxide. The above operation was further repeated twice. The formed thin film had a thickness of 0.15 μm, and was confirmed to be zinc oxide by XRD as shown in FIG. The visible light transmittance at 550 nm was 87%, and a transparent zinc oxide thin film having a transmittance of 80% or more was obtained.

[Example 2]
31.5 g of a partially hydrolyzed solution (concentration 5.5% by mass) containing gallium was obtained in the same manner as in Example 1 except that triethylaluminum was changed to trimethylgallium. The spectrum of FIG. 3 was obtained by NMR (THF-d8, ppm) measurement after removing the solvent and the like by vacuum drying.

  The product-containing coating solution containing the partial hydrolyzate obtained as described above was applied in the same manner as in Example 1. The formed thin film had a thickness of 0.14 μm, and was confirmed to be zinc oxide by XRD as shown in FIG. The visible light transmittance at 550 nm was 84%, and a transparent zinc oxide thin film having a transmittance of 80% or more was obtained.

[Example 3]
32.3 g of a partial hydrolyzate solution (concentration 5.5% by mass) containing indium was obtained in the same manner as in Example 1 except that triethylaluminum was changed to trimethylindium. The spectrum of FIG. 5 was obtained by NMR (THF-d8, ppm) measurement after removing the solvent and the like by vacuum drying.

  The product-containing coating solution containing the partial hydrolyzate obtained as described above was coated in the same manner as in Example 1 except that the substrate heating temperature was changed to 150 ° C. The formed thin film had a thickness of 0.14 μm, and was confirmed to be zinc oxide by XRD as shown in FIG. The visible light transmittance at 550 nm was 89%, and a transparent zinc oxide thin film having a transmittance of 80% or more was obtained.

[Comparative Example 1]
2-methoxyethanol (24.12 g), zinc acetate dihydrate (1.23 g), ethanolamine (0.34 g) as an auxiliary agent, and trisacetylacetonatoaluminum in a molar ratio of 0.02 to zinc acetate dihydrate The coating solution containing aluminum was obtained by adding sufficiently and stirring sufficiently.

  A thin film was obtained by carrying out the same operation as in Example 1 except that the coating solution thus obtained was used in the air. The visible light transmittance at 550 nm was 75%, and only an opaque thin film having a transmittance of 80% or less was obtained. Further, the film was non-uniform, and no peak derived from zinc oxide was observed from XRD (not shown).

[Comparative Example 2]
A coating solution containing gallium was obtained in the same manner as in Comparative Example 1 except that trisacetylacetonatoaluminum was changed to gallium chloride.

  The coating solution thus obtained was subjected to the same operation as in Comparative Example 1 to obtain a thin film. Further, the visible light transmittance at 550 nm was 66%, and only an opaque thin film having a transmittance of 80% or less was obtained. Further, the film was non-uniform, and no peak derived from zinc oxide was observed from XRD (not shown).

[Comparative Example 3]
A coating solution containing indium was obtained in the same manner as in Comparative Example 1 except that trisacetylacetonatoaluminum was changed to indium chloride tetrahydrate.

  The coating solution thus obtained was subjected to the same operation as in Comparative Example 1 to obtain a thin film. Further, the visible light transmittance at 550 nm was 71%, and only an opaque thin film having a transmittance of 80% or less was obtained. Further, the film was non-uniform, and no peak derived from zinc oxide was observed from XRD (not shown).

The present invention is useful in the field of manufacturing doped zinc oxide thin films.

Claims (14)

An organic zinc compound represented by the following general formula (1) and at least one of group 3B element compounds represented by the following general formula (2) or the following general formula (3) were dissolved in an electron-donating organic solvent. A solution obtained by adding water to the solution and at least partially hydrolyzing the organozinc compound, wherein the 3B group element compound has a molar ratio of 0.005 to 0 with respect to the organozinc compound. A composition for producing a doped zinc oxide thin film having a ratio of .3.
R ¹ —Zn—R ¹ (1)
(In the formula, R ¹ is a linear or branched alkyl group having 1 to 7 carbon atoms)
M _c X _d · aH ₂ O (2)
(Wherein M is a group 3B element, X is a halogen atom, nitric acid or sulfuric acid, c is 1, when d is a halogen atom or nitric acid, d is 3, and when X is sulfuric acid, c is 2 D is 3, and a is an integer of 0 to 9.)
R ² -M-R ³
| (L) _n (3)
R ⁴
(In the formula, M is a group 3B element, R ² , R ³ , and R ⁴ are independently hydrogen, a linear or branched alkyl group having 1 to 7 carbon atoms, or a linear or branched group having 1 to 7 carbon atoms. An alkoxyl group, a carboxylic acid group, or an acetylacetonate group, L is a coordinating organic compound containing nitrogen, oxygen or phosphorus, and n is an integer of 0 to 9.) The composition according to claim 1, wherein the product includes a hydrolyzate of the group 3B element compound. The composition according to claim 1 or 2, wherein the water is added in a molar ratio of 0.4 to 0.9 with respect to the total amount of the organic zinc compound and the group 3B element compound. Water is added to a solution in which the organozinc compound represented by the general formula (1) is dissolved in an electron-donating organic solvent to hydrolyze the organozinc compound at least partially, and then the general formula (2) or A product obtained by adding at least one group 3B element compound represented by the general formula (3) such that the molar ratio to the organozinc compound is 0.005 to 0.3; A composition for producing a doped zinc oxide thin film.
R ¹ —Zn—R ¹ (1)
(In the formula, R ¹ is a linear or branched alkyl group having 1 to 7 carbon atoms)
M _c X _d · aH ₂ O (2)
(Wherein M is a group 3B element, X is a halogen atom, nitric acid or sulfuric acid, c is 1, when d is a halogen atom or nitric acid, d is 3, and when X is sulfuric acid, c is 2 D is 3, and a is an integer of 0 to 9.)
R ² -M-R ³
| (L) _n (3)
R ⁴
(In the formula, M is a group 3B element, R ² , R ³ , and R ⁴ are independently hydrogen, a linear or branched alkyl group having 1 to 7 carbon atoms, or a linear or branched group having 1 to 7 carbon atoms. An alkoxyl group, a carboxylic acid group, or an acetylacetonate group, L is a coordinating organic compound containing nitrogen, oxygen or phosphorus, and n is an integer of 0 to 9.) The composition according to claim 4, wherein the product is substantially free of a hydrolyzate of the group 3B element compound. The composition according to claim 4 or 5, wherein the amount of water added is such that the molar ratio to the organozinc compound is in the range of 0.4 to 0.9. The composition according to any one of claims 1 to 6, wherein the content of the organic zinc compound represented by the general formula (1) is 0.5 wt% or less. The composition according to claim 1, comprising a solution obtained by dissolving the product in an organic solvent for forming a thin film different from the electron donating organic solvent. The composition according to claim 1, wherein the concentration of the product is in the range of 1 to 30% by mass. The composition according to claim 1, wherein the organozinc compound is a compound in which R ¹ is an alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. The composition according to claim 1, wherein the organic zinc compound is diethyl zinc. The composition according to any one of claims 1 to 11, wherein the electron-donating organic solvent is 1,4-dioxane. The composition according to any one of claims 1 to 12 is applied to a substrate surface, and then the obtained coating film is heated at a temperature of 300 ° C or lower to form a zinc oxide thin film doped with a group 3B element. A method for producing a doped zinc oxide thin film. The said doped zinc oxide thin film is a manufacturing method of Claim 13 which has an average transmittance | permeability of 80% or more with respect to visible light.

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