JP5308117B2 - Method for producing transparent conductive substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a transparent electroconductive substrate capable of developing excellent electroconductive properties by a simple coating method. <P>SOLUTION: The manufacturing method includes coating a precursor liquid containing a reaction product (A) between a titanium compound and hydrogen peroxide and a reaction product (B) between a niobium compound or a tantalum compound and hydrogen peroxide onto a transparent base material; firing the coating, heating the fired coating under a reducing atmosphere to perform annealing to form a transparent electroconductive film of niobium- or tantalum-doped titanium oxide having a specific resistance of &le;9&times;10<SP>-3</SP>&Omega; cm on the transparent base material. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a transparent conductive substrate having good conductivity and a method for producing the transparent conductive substrate by a simple coating method.

  Conventionally, as a transparent conductive substrate used for a solar cell, a liquid crystal display device or the like, a substrate provided with a conductive film such as an indium tin oxide (ITO) film or a zinc oxide (ZnO) film doped with Al is widely used. Has been. However, ITO film requires In (indium), which is a rare metal, so there is a demand for an alternative to other metals, and Al-doped ZnO film contains amphoteric elements, so it absorbs moisture. However, there is a drawback in that the application may be limited. Therefore, in recent years, development of transparent conductive substrates using titanium oxide has been promoted (see Patent Documents 1 and 2).

  By the way, generally, a method of forming a metal oxide thin film is roughly divided into a method of forming a film in a vacuum system, such as a sputtering method or a PLD (pulse laser deposition) method, and a slurry containing metal oxide particles or There is a method of heating after applying the solution to the substrate. The former has the problem that a large-scale device is required and the cost of equipment increases, and as a result, the cost of the product rises. On the other hand, the latter coating method is carried out inexpensively with a simple operation using existing equipment. This method is suitable for industrial mass production. However, until now, the former film forming method using a vacuum system has been generally employed for applications such as a transparent conductive film. This is because a film having higher conductivity than the latter coating method can be formed by the former vacuum film forming method. In other words, the film formed by the coating method is prone to cracking and it is difficult to produce a uniform film, and there is a tendency that the film is inferior in density compared to a film formed in a vacuum. Since necking between each other became weak, the conductivity was likely to decrease. In addition, the coating method is more likely to introduce impurities from outside the system than the vacuum film formation method, but the contamination of the formed film also impairs the denseness of the film. , Leading to a decrease in conductivity.

Japanese Patent Laid-Open No. 10-226598 JP 2005-11737 A

  Then, the subject of this invention is providing the manufacturing method of a transparent conductive substrate which manufactures the transparent conductive substrate which can express favorable electroconductivity with a simple coating method.

  The present inventor has intensively studied to solve the above problems. As a result, (A) a mixture containing a reaction product peroxylated by reacting hydrogen peroxide with a titanium compound and (B) a reaction product peroxylated by reacting hydrogen peroxide with a niobium compound or a tantalum compound ( After the precursor liquid, which is a precursor of a metal oxide, is applied on a transparent substrate and baked, and then annealed in a reducing atmosphere, titanium oxide doped with niobium or tantalum is obtained. The present invention has been completed by finding that a film having excellent conductivity can be formed.

That is, this invention consists of the following structures.
(1) A precursor liquid containing (A) a reaction product obtained by reacting a titanium compound with hydrogen peroxide and (B) a reaction product obtained by reacting a niobium compound or a tantalum compound with hydrogen peroxide on a transparent substrate. After being applied to the substrate and baked, it is subjected to annealing treatment by heating in a reducing atmosphere to form a transparent conductive film made of niobium or tantalum-doped titanium oxide on a transparent substrate. A method for producing a transparent conductive substrate having a specific resistance of 9 × 10 ⁻³ Ω · cm or less.
(2) The method for producing a transparent conductive substrate according to (1), wherein the heating temperature of the annealing treatment in a reducing atmosphere is 450 to 550 ° C.
(3) The method for producing a transparent conductive substrate according to (1) or (2), wherein a hydroxide is used as the (A) titanium compound and the (B) niobium compound or tantalum compound.
(4) The manufacturing method of the transparent conductive substrate in any one of said (1)-(3) which forms the transparent conductive film which has an anatase type crystal phase.
(5) The transparent conductive substrate obtained by the method in any one of said (1)-(4).

  According to the present invention, there is an effect that a transparent conductive substrate capable of expressing good conductivity can be manufactured by a simple coating method. That is, according to the present invention, it is possible to provide a transparent conductive substrate at low cost by a simple operation without requiring vacuum equipment. Furthermore, according to the present invention, since the temperature during the heat treatment can be set to a relatively low temperature, restrictions on the selection of the transparent substrate are reduced. For example, a flexible resin film having a low heat-resistant temperature is used as the transparent substrate. By using it, it becomes possible to produce a transparent conductive substrate by a so-called roll-to-roll method.

  In the method for producing a transparent conductive substrate of the present invention, first, as a film forming material, (A) a reaction product obtained by reacting hydrogen peroxide with a titanium compound and (B) a niobium compound or a tantalum compound (hereinafter referred to as “niobium”). Compound or tantalum compound "is collectively referred to as" dopant compound ", and" niobium or tantalum "is sometimes collectively referred to as" dopant ") to obtain a precursor liquid containing a reaction product obtained by reacting hydrogen peroxide with . This precursor liquid contains a complex (peroxy complex) in which (A) a titanium compound and (B) a niobium compound or a tantalum compound are peroxylated, and the peroxy complex is doped with niobium or tantalum by heating. It is a metal oxide precursor that becomes titanium oxide. In the present invention, film formation is performed with a metal oxide in which titanium oxide is doped with pentavalent niobium or tantalum belonging to group VA of the periodic table, thereby exhibiting good conductivity.

  The precursor liquid is obtained by reacting hydrogen peroxide with i) (B) dopant compound, and (B) a peroxy complex of titanium which is a reaction product obtained by reacting hydrogen peroxide with (A) titanium compound. The reaction product obtained may be obtained by mixing a peroxy complex of a dopant in a desired ratio, or ii) (A) a titanium compound and (B) a dopant compound in a desired ratio in advance. It may be obtained by reacting hydrogen peroxide with the mixture mixed in (1).

  In obtaining the precursor liquid, the mixing ratio of (A) the titanium compound or the peroxy complex derived from the titanium compound and (B) the dopant compound or the peroxy complex derived from the dopant compound is not particularly limited. The content ratio of the dopant (niobium or tantalum) in the formed titanium oxide film may be 0.1 to 40 mol%, preferably 5 to 30 mol%. When the amount of (B) (dopant compound or peroxy complex derived from the dopant compound) is less than the above range, the doping effect may be insufficient and the conductivity may be lowered. On the other hand, the above (B) may be less than the above range. At most, the conductivity may be lowered, or the transparency of the film may be lowered.

In obtaining the precursor liquid, the reaction with hydrogen peroxide (that is, the peroxylation reaction) is carried out by dissolving, for example, a titanium compound, a dopant compound or a mixture thereof with an appropriate solvent, and stirring the mixture as necessary. It can be carried out by adding about 60% by weight of hydrogen peroxide water. The amount of hydrogen peroxide to be reacted with the titanium compound or the dopant compound is not particularly limited, but usually 0.8 to 20 mol of hydrogen peroxide per 1 mol of titanium compound is added to the dopant for the titanium compound. What is necessary is just to make 0.8-20 mol hydrogen peroxide react with respect to a compound with respect to 1 mol dopant compound. The reaction time of the peroxylation reaction is usually about 1 second to 60 minutes, preferably about 5 minutes to 20 minutes. Since the peroxylation reaction with hydrogen peroxide usually involves intense heat generation, it is desirable to carry out the reaction while cooling (specifically, keeping the internal temperature at −10 ° C. or lower). After the reaction, the mixture may be further aged while being cooled to -10 ° C or lower.
The solvent that can be used in the peroxylation reaction with hydrogen peroxide is not particularly limited, but a water-based or alcohol-based water-soluble solvent is preferably used. Specific examples include water, methanol, ethanol, propanol, butanol, diacetone alcohol, and ethylene glycol.

The (A) titanium compound is not particularly limited as long as it contains Ti atoms as a titanium source. For example, titanium chloride (titanium dichloride, titanium trichloride, titanium tetrachloride, etc.), titanium alkoxide (methoxide, ethoxide, Isopropoxide, etc.), titanyl sulfate, metallic titanium, titanium hydroxide (orthotitanic acid), titanium oxysulfate, and the like can be used.
Of the dopant compounds (B), the niobium compound is not particularly limited as long as it contains Nb atoms as a niobium source. For example, niobium chloride, niobium alkoxide (methoxide, ethoxide, etc.), metal niobium, niobium hydroxide, etc. Can be used. On the other hand, the tantalum compound in the dopant compound (B) is not particularly limited as long as it contains Ta atoms as a tantalum source. Etc. can be used.
Of the above, titanium alkoxide, niobium alkoxide, and tantalum alkoxide are unstable substances that react immediately upon contact with moisture, and thus are preferably handled in a dry (low humidity) atmosphere.

  In the present invention, it is preferable to use a hydroxide as the (A) titanium compound and the (B) niobium compound or tantalum compound. That is, titanium hydroxide is used as (A) and niobium hydroxide or tantalum hydroxide is used as (B), or a titanium compound and a dopant compound other than these hydroxides are used to react with hydrogen peroxide. Prior to the formation, hydroxylation may be performed by adding alkali or water in advance, and the resulting hydroxide precipitate may be collected and washed. Thus, if it is a peroxy complex obtained by reacting a hydroxide with hydrogen peroxide, there will be no organic site containing carbon atoms, and it will be decomposed and volatilized by heating to a high temperature. Since it is not necessary, the heating temperature at the time of conversion into an oxide can be set at a relatively low temperature, which is preferable. For example, when a titanium compound other than hydroxide and a dopant compound are used as they are and reacted with hydrogen peroxide, an organic moiety exists in a part of the obtained peroxy complex, and this organic moiety is decomposed. In order to volatilize, it is necessary to heat to a temperature of at least 400 ° C. or more, preferably about 500 to 600 ° C.

The solid content concentration of the precursor liquid is usually preferably 10% by weight or less, and more preferably 2% by weight or less from the viewpoint of storage stability (pot life) of the precursor liquid. When the solid content concentration exceeds 10% by weight, the storage stability of the precursor liquid is significantly lowered, and the viscosity is increased at the time of coating, so that it may be difficult to uniformly coat on the transparent substrate.
In addition, solid content concentration here means the ratio (weight%) which the total weight of the titanium compound and dopant compound used when obtaining a precursor liquid accounts to the total weight of a precursor liquid.

In the method for producing a transparent conductive substrate of the present invention, next, the precursor liquid is applied on a transparent base material, baked, and then annealed under specific conditions.
The transparent substrate is not particularly limited as long as it can maintain its shape at the heating temperature in each step (for example, firing or annealing) where heat is applied and has transparency. . For example, inorganic materials such as various glass, thermoplastic resins and thermosetting resins (for example, epoxy resin, polymethyl methacrylate, polycarbonate, polystyrene, polyethylene sulfide, polyethersulfone, polyolefin, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose) Further, a plate-like material, a sheet-like material, a film-like material or the like formed of a polymer material such as plastics such as polyimide) can be used. The visible light transmittance of the transparent substrate is usually 90% or more, preferably 95% or more.

  The method for applying the precursor liquid on the transparent substrate is not particularly limited as long as it is a method capable of uniformly performing wet coating, and a conventionally known method can be employed. For example, a capillary coating method, a spin coating method, a slit die coating method, a spray coating method, a dip coating method, a roll coating method, a screen printing method, a flexographic printing method, a bar coater method, and the like can be employed.

  When the precursor liquid is applied, the amount of application is not particularly limited, and for example, the thickness of the finally formed film (dry film thickness) may be 10 nm to 300 nm. If the dry film thickness that is finally formed is smaller than the above range, there may be a place that is difficult to apply partially or a place that is not actually applied, such as when there is unevenness on the substrate, If it is larger than the above range, the transparency may be lowered. In addition, when apply | coating a precursor liquid in such thickness, you may carry out by one application | coating operation | work and may be made to carry out in multiple times.

The substrate after applying the precursor liquid is subsequently subjected to baking. Thereby, the peroxy complex (precursor liquid) on the base material changes to Nb or Ta-doped titanium oxide. The crystal state at this time usually consists of an amorphous phase.
The heating temperature at the time of firing is, for example, 500 ° C. or less, preferably 50 to 400 ° C. If the heating temperature at the time of firing is too high, a stable crystal phase may be deposited, and the effect of annealing treatment may not be observed. Moreover, what is necessary is just to set baking time suitably according to heating temperature etc., Usually, about 1 minute-1 hour, Preferably it is about 3 minutes-30 minutes. The firing may be performed in any atmosphere and is not particularly limited. For example, when the solid content concentration of the applied precursor liquid is low, the solvent may be uniformly volatilized by means such as vacuum drying or reduced pressure drying before firing, which facilitates the formation of a uniform film. .

  In the present invention, the fired substrate is annealed by heating in a reducing atmosphere. Thereby, the Nb or Ta doped titanium oxide forming the film undergoes a crystal transition from the amorphous phase to the anatase phase, and oxygen deficiency is generated in the crystal phase, thereby improving the conductivity. Moreover, usually, when oxygen deficiency is introduced, it tends to change to a highly resistant rutile crystal phase. However, in the present invention, niobium or tantalum doped in titanium oxide converts the anatase crystal phase even if oxygen deficiency is introduced. Since it acts to stabilize, it is possible to maintain a crystalline state capable of expressing high conductivity.

  There is no particular limitation on the reducing atmosphere in the annealing treatment, and for example, nitrogen, carbon monoxide, argon plasma, hydrogen plasma, hydrogen, vacuum, ammonia, inert gas (such as argon), or a mixed gas thereof. A general reducing atmosphere such as an atmosphere may be used. Preferably, a hydrogen atmosphere (100% hydrogen gas atmosphere) that is a strong reducing atmosphere is employed.

  The heating temperature in the annealing treatment may be any temperature at which the crystalline phase of niobium or tantalum-doped titanium oxide coated on the substrate and baked can be changed to an anatase type exhibiting high conductivity, and the content ratio of the dopant What is necessary is just to set suitably according to etc. The temperature necessary for changing to the anatase crystal phase increases as the amount of niobium or tantalum doped into titanium oxide increases, and the lower limit of the heating temperature for annealing is usually 450 ° C. or higher, preferably 500 ° C. or higher. It is. On the other hand, if the heating temperature is too high, the anatase crystal phase starts to change to a highly resistant rutile crystal phase, and the conductivity tends to decrease and the transparency of the film also tends to decrease. Usually, it is desirable to set the temperature within a range of 700 ° C. or lower, preferably 600 ° C. or lower, more preferably 550 ° C. or lower. However, the temperature when starting to change to the rutile crystal phase varies depending on the content ratio of the dopant, and when the content ratio of the dopant is relatively high, the crystal phase Does not change and the conductivity is not lowered. Specifically, when the content ratio of the dopant (the content ratio of niobium or tantalum in the formed transparent conductive film) is more than 10 mol%, even if the heating temperature of the annealing treatment is more than 550 ° C. The crystal phase does not change to the rutile type, and good conductivity is obtained. In addition to the above, the heat resistance temperature of the transparent substrate to be used is also taken into consideration when setting the heating temperature for the annealing treatment. For example, when alkali-free glass is used as the transparent substrate, it is usually 700 ° C. or lower, preferably 600 ° C. or lower, more preferably 550 ° C. or lower. The annealing time (heating time) may be appropriately set according to the heating temperature or the like, but is usually about 1 minute to 1 hour, preferably about 3 minutes to 30 minutes.

By the above method, a transparent conductive film made of titanium oxide doped with niobium or tantalum is formed on a transparent substrate. This transparent conductive film is a thin film made of a polycrystal of Nb or Ta-doped titanium oxide having an anatase type crystal phase, and exhibits high conductivity while exhibiting good transparency. Specifically, the specific resistance of the transparent conductive substrate obtained by the production method of the present invention is usually 9 × 10 ⁻³ Ω · cm or less, preferably 8 × 10 ⁻³ Ω · cm or less. The transmittance of the transparent conductive substrate obtained by the production method of the present invention is usually 70% or more in the visible light region, preferably 75% or more, more preferably 80% or more, and in the infrared region. Usually, it is 70% or more, preferably 75% or more, more preferably 80% or more. In addition, these transmittance | permeability and specific resistance can be measured by the method mentioned later in an Example, for example.

The transparent conductive substrate obtained by the production method of the present invention is, for example, a touch panel, a liquid crystal display, an LED (light emitting element), an organic EL display, a flexible display, a display electrode such as a plasma display, a solar cell electrode, or a window glass. It is suitably used for applications such as heat ray reflective films and antistatic films. Furthermore, the transparent conductive substrate obtained by the production method of the present invention is effective as an antistatic film having an antireflection function, taking advantage of its high refractive index.
In the production method of the present invention described above, the precursor liquid is applied directly on the transparent substrate. However, in the use of a transparent electrode such as a device such as a liquid crystal display, a colored film ( An intermediate film such as a color filter) may be interposed, and the precursor liquid may be applied directly on the intermediate film. In this manner, an intermediate film is interposed between the transparent substrate and the transparent conductive film. It is included in the scope of the present invention.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.
The physical properties of the transparent conductive substrate were measured by the following method.
<Specific Resistance> The specific resistance was measured by a four-terminal four-probe method using a resistivity meter (“LORESTA-GP, MCP-T610” manufactured by Mitsubishi Chemical Corporation). Specifically, four needle-shaped electrodes are placed on a straight line on the sample, a constant current is passed between the outer two probes, a constant current is passed between the inner two probes, and the inner two probes are The resulting potential difference was measured to determine the resistance.
<Transmissivity> The transmittance was measured in the range of 190 nm to 2700 nm using an ultraviolet-visible near-infrared spectrophotometer (“V-670” manufactured by JASCO Corporation).
<Crystallinity> Crystallinity was evaluated using an attachment for thin film measurement using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation).
<Crystal structure> While examining the doped state of niobium or tantalum to titanium using an energy dispersive X-ray microanalyzer (TEM-EDX), the crystal structure was examined using a field emission electron microscope (FE-SEM). .
In the following Examples and Comparative Examples, when a precursor liquid is obtained by mixing a titanium peroxy complex and a niobium peroxy complex, dehydrated ethanol is used to obtain a desired solid content concentration unless otherwise specified. It was adjusted.

Example 1
First, 4.0 g of titanium tetraisopropoxide was dissolved in 28.5 g of dehydrated ethanol in an argon gas atmosphere, and 8.0 g of hydrogen peroxide solution having a concentration of 30% by weight was gradually added to the resulting solution with stirring. Then, after completion of the addition, the mixture was stirred for 5 minutes to allow peroxylation reaction. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product thus obtained was designated as titanium peroxy complex (a1).

  On the other hand, 1.5 g of niobium pentaethoxide was dissolved in 19.2 g of dehydrated ethanol in an argon gas atmosphere, and 1.6 g of hydrogen peroxide solution having a concentration of 30% by weight was gradually added to the resulting solution with stirring. After completion of the addition, the mixture was stirred for 5 minutes to cause a peroxylation reaction. As in the above, the reaction is performed while cooling the periphery of the flask containing the solution with dry ice so that the internal temperature of the solution does not exceed −10 ° C. when heat is generated by the addition of hydrogen peroxide. Controlled. The reaction product thus obtained was designated as niobium peroxy complex (b1).

Next, the titanium peroxy complex (a1) and the niobium peroxy complex (b1) are mixed at a ratio of titanium: niobium = 93: 7 (molar ratio), and a precursor having a solid content concentration of 7% by weight is mixed. Body fluid. This precursor solution was applied once on a transparent substrate (non-alkali glass “Corning Corporation 1737”, thickness 0.7 mm) by a capillary coater so as to have a dry film thickness of 35.7 nm, and 10 ° C. at 400 ° C. The substrate was baked (prebaked) for 30 minutes, and then annealed at 500 ° C. for 60 minutes in a reducing atmosphere of 100% hydrogen to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 5.2 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

(Example 2)
First, 20.0 g of distilled water was added to 3.0 g of titanium tetraisopropoxide in an argon gas atmosphere and stirred, and the resulting precipitate (titanium hydroxide) was collected from the mother liquor. 1.2 g of this precipitate was dissolved in 2.0 g of ethanol, and 17 g of hydrogen peroxide solution having a concentration of 30% by weight was gradually added to the resulting solution with stirring. It was made to react. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product thus obtained was designated as titanium peroxy complex (a2).

  On the other hand, 40.0 g of distilled water was added to 5.0 g of niobium pentaethoxide in an argon gas atmosphere and stirred, and the resulting precipitate (niobium hydroxide) was collected from the mother liquor. 2.8 g of this precipitate was dissolved in 2.0 g of ethanol, and 20 g of hydrogen peroxide solution having a concentration of 30% by weight was gradually added to the resulting solution with stirring. It was made to react. As in the above, the reaction is performed while cooling the periphery of the flask containing the solution with dry ice so that the internal temperature of the solution does not exceed −10 ° C. when heat is generated by the addition of hydrogen peroxide. Controlled. The reaction product thus obtained was designated as niobium peroxy complex (b2).

Next, the titanium peroxy complex (a2) and the niobium peroxy complex (b2) are mixed at a ratio of titanium: niobium = 94: 6 (molar ratio), and the solid content concentration is 6.5% by weight. The precursor liquid was used. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 26.0 nm, baked (prebaked) at 80 ° C. for 10 minutes, and then 100% hydrogen. An annealing treatment was performed at 500 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 7.3 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

(Example 3)
The titanium peroxy complex (a2) obtained in Example 2 and the niobium peroxy complex (b2) were mixed at a ratio such that titanium: niobium = 92: 8 (molar ratio), and the solid content concentration was 6.5. A weight percent precursor solution was obtained. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 55.0 nm, baked (prebaked) at 80 ° C. for 10 minutes, and then 100% hydrogen. An annealing treatment was performed at 500 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 6.5 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

Example 4
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio of titanium: niobium = 92: 8 (molar ratio), and the solid content concentration was 9.16. A weight percent precursor solution was obtained. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 71.0 nm, baked (prebaked) at 80 ° C. for 10 minutes, and then 100% hydrogen. An annealing treatment was performed at 500 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 5.6 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

(Example 5)
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio such that titanium: niobium = 80: 20 (molar ratio), and the solid content concentration was 7% by weight. The precursor liquid was used. This precursor solution was applied once by a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 100 nm, baked (prebaked) at 300 ° C. for 10 minutes, and then 100% hydrogen. Annealing treatment was performed at 500 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 5.0 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in this transparent conductive substrate was examined by X-ray diffraction, it was an anatase type with high crystallinity as shown in FIG. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

(Example 6)
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio such that titanium: niobium = 70: 30 (molar ratio), and the solid content concentration was 7% by weight. The precursor liquid was used. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 65 nm, baked (prebaked) at 300 ° C. for 10 minutes, and then 100% hydrogen. Annealing treatment was performed at 500 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 4.0 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

(Example 7)
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio such that titanium: niobium = 80: 20 (molar ratio), and the solid content concentration was 7% by weight. The precursor liquid was used. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 50 nm, baked (prebaked) at 300 ° C. for 10 minutes, and then 100% hydrogen. Annealing treatment was performed at 550 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 3.7 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

(Example 8)
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio such that titanium: niobium = 80: 20 (molar ratio), and the solid content concentration was 7% by weight. The precursor liquid was used. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 60 nm, baked (prebaked) at 300 ° C. for 10 minutes, and then 100% hydrogen. Annealing treatment was performed at 600 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 1.8 × 10 ⁻³ Ω · cm, and the transmittance was about 70% in the visible region and about 70% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystal of titanium oxide doped with Nb.

Example 9
In an argon gas atmosphere, 1.6 g of tantalum pentaethoxide is dissolved in 20.4 g of dehydrated ethanol, and 1.36 g of hydrogen peroxide solution having a concentration of 30% by weight is gradually added to the resulting solution under stirring. After completion, the mixture was stirred for 5 minutes to allow peroxylation. The reaction was conducted while cooling the periphery of the flask containing the solution with dry ice, and the internal temperature of the solution was controlled so as not to exceed −10 ° C. when heat was generated by the addition of hydrogen peroxide. The reaction product thus obtained was designated as a tantalum peroxy complex (c1).

Next, the titanium peroxy complex (a1) obtained in Example 1 and the tantalum peroxy complex (c1) were mixed at a ratio of titanium: tantalum = 80: 20 (molar ratio) to obtain a solid content. A precursor solution having a concentration of 7% by weight was obtained. This precursor solution was applied once on the same transparent substrate as in Example 1 with a capillary coater so as to have a dry film thickness of 67.3 nm, baked (prebaked) at 100 ° C. for 30 minutes, and then hydrogenated. Annealing treatment was performed at 500 ° C. for 30 minutes in a 100% reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 8.3 × 10 ⁻³ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type. Moreover, when the crystal structure was observed by TEM-EDX and FE-SEM, it was a polycrystalline body of titanium oxide doped with Ta.

(Comparative Example 1)
The titanium peroxy complex (a2) obtained in Example 2 was used alone to obtain a precursor liquid having a solid content concentration of 9.4 wt%. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 102 nm, baked (prebaked) at 80 ° C. for 10 minutes, and then reduced to 100% hydrogen. An annealing treatment was performed at 500 ° C. for 60 minutes in an atmosphere to obtain a transparent conductive substrate.
Since the obtained transparent conductive substrate is obtained without doping titanium oxide with a dopant (niobium or tantalum), its specific resistance is not measurable (measurement limit: 10 ³ Ω · cm or more). The transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type.

(Comparative Example 2)
The titanium peroxy complex (a2) obtained in Example 2 and the niobium peroxy complex (b2) were mixed at a ratio such that titanium: niobium = 92: 8 (molar ratio), and the solid content concentration was 6.5. A weight percent precursor solution was obtained. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 55.0 nm, baked (prebaked) at 80 ° C. for 10 minutes, and then a normal large size Annealing treatment was performed at 500 ° C. for 60 minutes under atmospheric pressure to obtain a transparent conductive substrate.
Since the obtained transparent conductive substrate was obtained by performing the annealing treatment in an atmospheric pressure atmosphere instead of a reducing atmosphere, its specific resistance was not measurable (measurement limit: 10 ³ Ω · cm or more). The transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type.

(Comparative Example 3)
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio such that titanium: niobium = 80: 20 (molar ratio), and the solid content concentration was 7% by weight. The precursor liquid was used. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 80 nm, air-dried (at room temperature for 60 minutes), and then reduced to 100% hydrogen. Underneath, annealing was performed at 500 ° C. for 60 minutes to obtain a transparent conductive substrate.
Since the obtained transparent conductive substrate was obtained without firing, the specific resistance was 5.8 × 10 ⁻² Ω · cm, and the transmittance was about 80% in the visible region, About 80% in the infrared region.
When the crystal phase of the conductive film in the transparent conductive substrate was examined by X-ray diffraction, it was an anatase type.

(Comparative Example 4)
The titanium peroxy complex (a2) obtained in Example 2 and the niobium peroxy complex (b2) were mixed at a ratio such that titanium: niobium = 92: 8 (molar ratio), and the solid content concentration was 6.5. A weight percent precursor solution was obtained. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so as to have a dry film thickness of 55.0 nm, baked (prebaked) at 80 ° C. for 10 minutes, and then 100% hydrogen. An annealing treatment was performed at 600 ° C. for 60 minutes in a reducing atmosphere to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 5.4 × 10 ⁻¹ Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in this transparent conductive substrate was examined by X-ray diffraction, it was found that a rutile type was partially formed.

(Comparative Example 5)
The titanium peroxy complex (a1) obtained in Example 1 and the niobium peroxy complex (b1) were mixed at a ratio such that titanium: niobium = 85: 15 (molar ratio), and the solid content concentration was 7% by weight. The precursor liquid was used. This precursor solution was applied once with a spin coater on the same transparent substrate as in Example 1 so that the dry film thickness was 100 nm,
After baking (pre-baking) at 300 ° C. for 10 minutes, annealing treatment was performed at 420 ° C. for 60 minutes in a reducing atmosphere of 100% hydrogen to obtain a transparent conductive substrate.
The specific resistance of the obtained transparent conductive substrate was 5.4 × 10 ⁻² Ω · cm, and the transmittance was about 80% in the visible region and about 80% in the infrared region.
When the crystal phase of the conductive film in this transparent conductive substrate was examined by X-ray diffraction, it was anatase type as shown in FIG. 2, but the crystallinity was low.

6 is a graph showing an X-ray diffraction peak of a conductive film in a transparent conductive substrate obtained in Example 5. FIG. 10 is a graph showing an X-ray diffraction peak of a conductive film in a transparent conductive substrate obtained in Comparative Example 5.

Claims (4)

(A) A precursor liquid containing a reaction product obtained by reacting hydrogen peroxide with a titanium compound and (B) a reaction product obtained by reacting hydrogen peroxide with a niobium compound or a tantalum compound is applied onto a transparent substrate. The specific resistance is characterized in that after firing, annealing is performed by heating in a reducing atmosphere to form a transparent conductive film made of titanium oxide doped with niobium or tantalum on a transparent substrate. A method for producing a transparent conductive substrate of 9 × 10 ⁻³ Ω · cm or less.   The manufacturing method of the transparent conductive substrate of Claim 1 whose heating temperature of the annealing process in a reducing atmosphere is 450-550 degreeC.   The manufacturing method of the transparent conductive substrate of Claim 1 or 2 using a hydroxide as said (A) titanium compound and said (B) niobium compound or a tantalum compound. The manufacturing method of the transparent conductive substrate in any one of Claims 1-3 which forms the transparent conductive film which has an anatase type crystal phase.

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