WO2014196460A1

WO2014196460A1 - Transparent conductor and method for producing same

Info

Publication number: WO2014196460A1
Application number: PCT/JP2014/064369
Authority: WO
Inventors: 仁一粕谷; 一成多田; 健波木井; 小島　茂; 和央吉田
Original assignee: コニカミノルタ株式会社
Priority date: 2013-06-07
Filing date: 2014-05-30
Publication date: 2014-12-11
Also published as: JP2016149183A

Abstract

The present invention relates to a transparent conductor having a low surface electrical resistivity and high optical transparency, and also to a method for producing the same. Conventional ITO films pose problems in that sufficiently reducing surface electrical resistivity is difficult, and ITO films are not suited to uses that require flexibility because they have a tendency toward cracking. Therefore, thin films formed from Ag are being recommended as transparent conductor films, and transparent conductors and the like obtained by laminating a base layer formed from aluminum and an Ag layer are being recommended. Nevertheless, there is a need for a reduction in the visible-light average transmittance and a further increase in optical transparency. The present invention provides a transparent conductor that has both a high transparency and a low surface electrical resistivity as a result of a configuration comprising, in the following order, a transparent substrate, a base layer containing molybdenum and having a layer thickness of 2 nm or less, and a transparent metal film disposed adjacent to the base layer and having a film thickness of 15 nm or less.

Description

Transparent conductor and method for producing the same

The present invention relates to a transparent conductor and a manufacturing method thereof. More specifically, the present invention relates to a transparent conductor having a low surface electrical resistance value and high light transmittance, and a method for manufacturing the same.

In recent years, electrode materials for display devices such as liquid crystal displays, plasma displays, inorganic and organic electroluminescence (hereinafter abbreviated as “EL”) displays, electrode materials for inorganic and organic EL elements, touch panel materials, solar cell materials, etc. Transparent conductive films are used in various devices.

As a material constituting such a transparent conductive film, metals such as Au, Ag, Pt, Cu, Rh, Pd, Al, and Cr, In ₂ O ₃ , CdO, CdIn ₂ O ₄ , Cd ₂ SnO ₄ , and TiO _{2 are used.} , SnO ₂ , ZnO, ITO (indium tin oxide) and other oxide semiconductors are known.

In recent years, a capacitive touch panel has been developed. In this method, a transparent conductive film having a low surface electrical resistance value and high transparency is required. However, with an ITO film, it is difficult to sufficiently reduce the surface electrical resistance value. In addition, the ITO film is easily broken and cannot be applied to applications that require flexibility.
Therefore, a transparent conductive film in which Ag is formed in a mesh shape has been proposed as a transparent conductive film that replaces ITO (Patent Document 1). In addition, a transparent conductive film coated with carbon nanotubes or Ag nanowires has also been proposed (Patent Documents 2 and 3). Furthermore, it has been proposed to use a thin film made of Ag as a transparent conductive film, and a transparent conductor in which an underlayer made of aluminum and an Ag layer are laminated has also been proposed (Patent Document 4).

However, the Ag mesh described in Patent Document 1 has a metal part having a line width of about 20 μm. Therefore, the Ag mesh is easily visible and cannot be applied to uses that require high transparency.
Moreover, the transparent conductive film of patent document 2 and patent document 3 still has a high surface electrical resistance value. Therefore, it is required to further reduce the surface electrical resistance value.
On the other hand, the transparent conductor of Patent Document 4 has a low average transmittance of visible light and is required to further increase the light transmittance.

JP 2006-352073 A Japanese translation of PCT publication No. 2004-526838 JP 2011-167848 A JP 2008-171737 A

The present invention has been made in view of the above situation. An object of the present invention is to provide a transparent conductor having a low surface electrical resistance value and high light transmittance and a method for producing the same.

In order to solve the above-mentioned problems, the present inventor can obtain a transparent conductor having a low surface electrical resistance value and a high light transmittance by incorporating molybdenum into the underlayer in the process of examining the cause of the above-mentioned problems. As a result, the present invention was reached.
That is, the said subject which concerns on this invention is solved by the following means.

1. A transparent substrate;
An underlayer containing molybdenum and having a layer thickness of 2 nm or less;
A transparent metal film disposed adjacent to the base layer and having a thickness of 15 nm or less;
Transparent conductors including

2. A high refractive index layer including a dielectric material or an oxide semiconductor material having a higher refractive index of light having a wavelength of 570 nm than that of the transparent substrate is provided between the transparent substrate and the base layer or on the transparent metal film. The transparent conductor according to item 1, further comprising:

3. A low refractive index layer containing a dielectric material or an oxide semiconductor material having a refractive index of light having a wavelength of 570 nm of 1.8 or less between at least one of the transparent substrate and the base layer or on the transparent metal film. The transparent conductor according to

item

1 or 2, further comprising:

4). A method for producing a transparent conductor comprising a transparent substrate, molybdenum, an underlayer having a layer thickness of 2 nm or less, and a transparent metal film having a film thickness of 15 nm or less in this order,
Forming the underlayer on the transparent substrate by vapor deposition or sputtering;
Forming the transparent metal film on the underlayer by a vapor deposition method;
The manufacturing method of the transparent conductor containing this.

According to the present invention, a transparent conductor having both high transparency and a low surface electric resistance value can be obtained.
The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.
That is, in the transparent conductor according to the present invention, the underlying layer containing molybdenum is disposed between the transparent substrate and the transparent metal film. The layer containing molybdenum is easily formed uniformly by a general vapor deposition method. Molybdenum is difficult to migrate (move) on the film formation surface (for example, the surface of the transparent substrate), and it is difficult to form an island structure. When a transparent metal film is formed on such an underlayer, constituent atoms of the transparent metal film are difficult to migrate, and the transparent metal film becomes a smooth film even if the film thickness is small.
Therefore, in the transparent conductor of this invention, it is guessed that high light transmittance and low surface electrical resistance value can be compatible. Details of the mechanism of the effect will be described later.

Schematic sectional view showing an example of the layer structure of the transparent conductor of the present invention Schematic sectional view showing another example of the layer structure of the transparent conductor of the present invention The graph which shows the light transmittance of the transparent conductor of the Example and comparative example of this invention The graph which shows the light absorption rate of the transparent conductor of the Example and comparative example of this invention

The transparent conductor of the present invention has a transparent substrate, a base layer containing molybdenum and having a layer thickness of 2 nm or less, a layer adjacent to the base layer, and a film thickness of 15 nm or less. A transparent metal film is included in this order. This feature is a technical feature common to the inventions according to claims 1 to 4.
As an embodiment of the present invention, from the viewpoint of manifesting the effect of the present invention, at least one of the refractive index of light having a wavelength of 570 nm between the transparent substrate and the base layer or on the transparent metal film from the transparent substrate. It is preferable that it is a transparent conductor of the aspect which further has a high refractive index layer containing a high dielectric material or oxide semiconductor material.
Further, the transparent conductor is a dielectric material or an oxide semiconductor having a refractive index of light having a wavelength of 570 nm of 1.8 or less between at least one of the transparent substrate and the base layer or on the transparent metal film. It is preferable to further have a low refractive index layer containing a material.
The method for producing a transparent conductor of the present invention includes a transparent substrate, an underlayer containing molybdenum and having a layer thickness of 2 nm or less, and a transparent metal film having a thickness of 15 nm or less in this order. A method for producing a transparent conductor, comprising: forming a base layer on the transparent substrate by vapor deposition or sputtering; and forming the transparent metal film on the base layer by vapor deposition. It is necessary to be a manufacturing method of an aspect including the process to form into a film. With this manufacturing method, a transparent conductor having a low surface electrical resistance value and a high light transmittance can be obtained.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In the present application, “˜” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

1. About a transparent conductor The example of a layer structure of the transparent conductor of this invention is shown in FIG.1 and FIG.2. As shown in FIGS. 1 and 2, the transparent conductor 100 of the present invention is a laminate in which a transparent substrate 1 / underlayer 2 / transparent metal film 3 are laminated in this order.
As shown in FIG. 2, the transparent conductor 100 may include other layers as necessary.
For example, the underlayer 2 and the transparent metal film 3 may be sandwiched between the first high refractive index layer 4 and the second high refractive index layer 5 having a high refractive index. Only one of the first high refractive index layer 4 and the second high refractive index layer 5 may be formed, or both may be formed, and preferably both may be formed.
Further, instead of or in addition to the first high-refractive index layer 4 and the second high-refractive index layer 5, the base layer 2 and the transparent metal are formed on the surface of the base layer 2 on the transparent substrate 1 side or on the transparent metal film 3. A first low refractive index layer 6 and a second low refractive index layer 7 for suppressing plasmon absorption of the film 3 may be included. Only one of the first low refractive index layer 6 and the second low refractive index layer 7 may be formed, or both may be formed, and preferably both may be formed.

When a transparent metal film made of Ag or the like was directly formed on a transparent substrate, it was difficult to obtain a transparent metal film having both high light transmittance and low surface electric resistance. The reason is guessed as follows. When an Ag layer is formed on a substrate by a general vapor deposition method, Ag atoms that reach the transparent substrate migrate (surface move) on the transparent substrate at the initial stage of film formation. A large number of Ag atoms gather to form a discontinuous island structure.

Further, when Ag atoms are supplied, an Ag film grows starting from the island-like structure, and a part of adjacent lumps are connected to enable electrical conduction. However, if the thickness of the Ag film is thin, the gap between the chunks is not completely filled. Therefore, plasmon absorption occurs, and the light transmittance is not sufficiently increased. On the other hand, when the thickness of the Ag film is increased, the surface of the Ag film becomes smooth, so that the surface electrical resistance value is lowered and plasmon absorption is not generated. However, since Ag inherent reflection occurs, the light transmittance of the Ag layer does not increase.

Therefore, as described above, it has been proposed to dispose an underlayer made of aluminum between the transparent substrate and the Ag layer. However, even with this method, the plasmon absorption could not be sufficiently suppressed. This is because the affinity between atoms (aluminum, etc.) constituting the underlayer and Ag is not sufficient, and it is difficult for the underlayer to become a growth nucleus, or the atoms constituting the underlayer are migrated in the same way as Ag atoms. And it is guessed that it is because it is easy to form a discontinuous island-like structure (large lump).

On the other hand, in the transparent conductor 100 of the present invention, the underlying layer 2 made of molybdenum or an alloy with another metal containing 20 mass% or more of molybdenum is disposed between the transparent substrate 1 and the transparent metal film 3. It is installed. A layer containing a certain amount or more of molybdenum is easily formed uniformly by a general vapor deposition method. Molybdenum is difficult to migrate on the film formation surface (for example, the surface of the transparent substrate 1), and it is difficult to form the aforementioned island-like structure. When the transparent metal film 3 is formed on such an underlayer 2, the constituent atoms of the transparent metal film 3 are difficult to migrate, and the transparent metal film 3 becomes a smooth film even if the film thickness is small. Therefore, the transparent conductor 100 of the present invention achieves both high light transmittance and low surface electrical resistance.

1.1) Transparent substrate The transparent substrate 1 contained in the transparent conductor 100 can be the same as the transparent substrate of various display devices. As the transparent substrate 1, a glass substrate, or a cellulose ester resin (for example, triacetyl cellulose, diacetyl cellulose, acetyl propionyl cellulose, etc.), a polycarbonate resin (for example, Panlite, Multilon (both manufactured by Teijin Limited)), a cycloolefin resin ( For example, Zeonore (manufactured by Nippon Zeon), Arton (manufactured by JSR), Appel (manufactured by Mitsui Chemicals), acrylic resin (for example, polymethyl methacrylate, "Acrylite (manufactured by Mitsubishi Rayon), Sumipex (manufactured by Sumitomo Chemical)) ), Polyimide, phenol resin, epoxy resin, polyphenylene ether (PPE) resin, polyester resin (eg, polyethylene terephthalate (PET), polyethylene naphthalate), polyether sulfone, ABS / AS resin, MBS resin Examples include transparent resin films made of polystyrene, methacrylic resin, polyvinyl alcohol / EVOH (ethylene vinyl alcohol resin), styrene block copolymer resin, etc. When the transparent substrate is a transparent resin film, the film is composed of one kind of resin. It may be made of two or more kinds of resins.

From the viewpoint of transparency, the transparent substrate 1 is a glass substrate, or a cellulose ester resin, a polyester resin (particularly polyethylene terephthalate), a triacetyl cellulose, a cycloolefin resin, a phenol resin, an epoxy resin, a polyphenylene ether (PPE) resin, a polyether sulfone. A film made of ABS / AS resin, MBS resin, polystyrene, methacrylic resin, polyvinyl alcohol / EVOH (ethylene vinyl alcohol resin) and styrene block copolymer resin is preferable.

The transparent substrate 1 preferably has high transparency to visible light, and the average transmittance of light within a wavelength range of 450 to 800 nm is preferably 70% or more, more preferably 80% or more, and 85 % Or more is more preferable. When the average light transmittance of the transparent substrate 1 is 70% or more, the light transmittance of the transparent conductor 100 is likely to be increased. Further, the average absorptance of light within the wavelength range of 450 to 800 nm of the transparent substrate 1 is preferably 10% or less, more preferably 5% or less, and further preferably 3% or less.

The average transmittance of the transparent substrate 1 is measured by making light incident from an angle inclined by 5 ° with respect to the normal of the surface of the transparent substrate 1. On the other hand, the average absorptance of the transparent substrate 1 is measured by making the light incident from the same angle as the average transmissivity and measuring the average reflectivity of the transparent substrate 1. Average absorptivity = 100− (average transmissivity + average reflectivity) ). Average transmittance and average reflectance are measured with a spectrophotometer.

The refractive index of light having a wavelength of 570 nm of the transparent substrate 1 is preferably 1.40 to 1.95, more preferably 1.45 to 1.75, and still more preferably 1.45 to 1.70. . The refractive index of the transparent substrate is usually determined by the material of the transparent substrate. The “refractive index” of the transparent substrate is irradiated with a light beam having a predetermined wavelength (for example, 570 nm) in an atmosphere of a temperature of 25 ° C. and a relative humidity of 55% RH, and an Abbe refractometer (DR-M2 manufactured by ATAGO) is used. It is the value measured using (the refractive index of other members is also the same).

The haze value of the transparent substrate 1 is preferably 0.01 to 2.5, more preferably 0.1 to 1.2. The haze value of the transparent conductor 100 can be suppressed as the haze value of the transparent substrate is 2.5 or less. The haze value is measured with a haze meter.

The thickness of the transparent substrate 1 is preferably 1 μm to 20 mm, more preferably 10 μm to 2 mm. When the thickness of the transparent substrate is 1 μm or more, the strength of the transparent substrate 1 is increased, and the first high refractive index layer 4 is difficult to be cracked or torn. On the other hand, if the thickness of the transparent substrate 1 is 20 mm or less, the flexibility of the transparent conductor 100 is sufficient. Furthermore, the thickness of the apparatus using the transparent conductor 100 can be reduced. Moreover, the apparatus using the transparent conductor 100 can also be reduced in weight.

1.2) Underlayer The underlayer 2 is disposed between the transparent substrate 1 and the transparent metal film 3 and in contact with the transparent metal film 3. The underlayer 2 is a layer made of molybdenum alone or an alloy of molybdenum and another metal. The amount of molybdenum contained in the underlayer 2 is 20% by mass or more, preferably 40% by mass or more, and more preferably 60% by mass or more. From the viewpoint of cost, it is desirable that the amount of molybdenum is large.

As described above, when the base layer 2 contains 20 mass% or more of molybdenum atoms, the layer thickness and density of the base layer 2 tend to be uniform, and the surface smoothness of the transparent metal film 3 tends to increase. Molybdenum has a high affinity with the atoms constituting the transparent metal film 3. Therefore, when the base layer 2 contains 20% by mass or more of molybdenum, the adhesion between the base layer 2 and the transparent metal film 3 is likely to increase.

Examples of metals other than molybdenum contained in the underlayer 2 include indium other than molybdenum, platinum group, gold, cobalt, nickel, palladium, titanium, aluminum, chromium, niobium, and zinc. The underlayer 2 may contain only one kind of these metals or two or more kinds. Among these metals, palladium and indium are preferable.

The layer thickness of the underlayer 2 is 2 nm or less, preferably 0.5 nm or less. The underlayer 2 is more preferably a monoatomic film. Furthermore, the underlayer 2 may be a film in which metal atoms are adhered to the transparent substrate 1 while being separated from each other. If metal atoms are attached to the transparent substrate 1 at a distance from each other, atoms that are the material of the transparent metal film 3 are difficult to migrate when the transparent metal film 3 is formed. Furthermore, the transparent metal film 3 tends to grow from this metal atom as a starting point, and the transparent metal film 3 tends to become flat.

1.3) Transparent Metal Film The transparent metal film 3 is a film for conducting electricity in the transparent conductor 100, and is disposed adjacent to the base layer 2. The metal contained in the transparent metal film 3 is not particularly limited as long as it is a highly conductive metal, and examples thereof include silver, copper, gold, platinum group, titanium, and chromium. The transparent metal film 3 may contain only one kind of these metals or two or more kinds. From the viewpoint of high conductivity, the transparent metal film 3 is preferably made of silver or an alloy containing 90 at% or more of silver. Examples of the metal combined with silver include zinc, gold, copper, palladium, aluminum, manganese, bismuth, neodymium, and molybdenum. For example, when silver and zinc are combined, the sulfidation resistance of the transparent metal film is enhanced. When silver and gold are combined, salt resistance (NaCl) resistance increases. Furthermore, when silver and copper are combined, the oxidation resistance increases. As for the metal combined with silver, only 1 type may be combined among the said metals, and 2 or more types may be combined.

In addition, the plasmon absorption rate of the transparent metal film 3 is preferably 10% or less over the entire wavelength range of 400 to 800 nm. The plasmon absorption rate of the transparent metal film 3 is more preferably 7% or less, and further preferably 5% or less.

The plasmon absorption rate in the wavelength range of 400 to 800 nm of the transparent metal film 3 is measured by the following procedure.
(I) Molybdenum (molybdenum content 20% by mass) is formed to a thickness of 0.1 nm on a glass substrate using a magnetron sputtering apparatus. The average film thickness of molybdenum is calculated from the film formation rate of the manufacturer's nominal value of the sputtering apparatus. Thereafter, a film made of the same metal as the object to be measured is formed on the substrate to which molybdenum is attached with a vapor deposition machine to a thickness of 20 nm.

(Ii) Then, measurement light is incident from an angle inclined by 5 ° with respect to the normal of the surface of the obtained metal film, and the transmittance and reflectance of the metal film are measured. Then, from the transmittance and reflectance at each wavelength, absorption rate = 100− (transmittance + reflectance) is calculated and used as reference data. The transmittance and reflectance are measured with a spectrophotometer.

(Iii) Subsequently, the transmittance and reflectance of the transparent metal film to be measured are measured in the same manner. Then, the reference data is subtracted from the obtained absorption rate, and the calculated value is defined as the plasmon absorption rate.

The film thickness of the transparent metal film 3 is 15 nm or less, preferably 3 to 13 nm, and more preferably 7 to 12 nm. If the film thickness of the transparent metal film 3 is 15 nm or less, reflection of the metal contained in the transparent metal film 3 hardly occurs and the light transmittance of the transparent conductor 100 is likely to increase.

1.4) First High Refractive Index Layer and Second High Refractive Index Layer The transparent conductor 100 of the present invention has a relatively refractive index so as to sandwich the underlayer 2 and the transparent metal film 3 as described above. High layers, that is, the first high refractive index layer 4 and the second high refractive index layer 5 may be provided. The reflection characteristics of the transparent conductor 100 greatly depend on the layer configuration of the transparent conductor 100. And when the 1st high refractive index layer 4 and the 2nd high refractive index layer 5 are arrange | positioned so that the base layer 2 and the transparent metal film 3 may be pinched | interposed, the reflectance of the transparent conductor 100 surface will fall, and transparent The light transmittance of the conductor 100 is likely to increase.

The first high-refractive index layer 4 and the second high-refractive index layer 5 include a dielectric material or an oxide semiconductor material in which the refractive index of light having a wavelength of 570 nm is higher than the refractive index of light having a wavelength of 570 nm of the transparent substrate 1. It is preferred that The refractive index of light having a wavelength of 570 nm of the dielectric material or oxide semiconductor material is preferably 0.1 to 1.1 larger than the refractive index of light having a wavelength of 570 nm of the transparent substrate 1, and is preferably 0.4 to 1.0. Larger is more preferable. The refractive index of light having a specific wavelength of 570 nm of the dielectric material or the oxide semiconductor material contained in the first high refractive index layer 4 and the second high refractive index layer 5 is preferably larger than 1.5, Is more preferably 2.5, and still more preferably 1.8 to 2.5. When the refractive index of the dielectric material or the oxide semiconductor material is larger than 1.5, the reflectance of the transparent conductor 100 is likely to be lowered by the first high refractive index layer 4 and the second high refractive index layer 5. In addition, the refractive index of the 1st high refractive index layer 4 and the 2nd high refractive index layer 5 is adjusted with the refractive index of the said dielectric material or an oxide semiconductor material, and the density of each layer.

The dielectric material or the oxide semiconductor material included in the first high refractive index layer 4 and the second high refractive index layer 5 may be an insulating material or a conductive material. The dielectric material or oxide semiconductor material contained in the first high refractive index layer 4 and the second high refractive index layer 5 is preferably a metal oxide or a metal sulfide. Examples of metal oxides or metal sulfides include TiO ₂ , ITO (indium tin oxide), ZnO, ZnS, Nb ₂ O ₅ , ZrO ₂ , CeO ₂ , Ta ₂ O ₅ , Ti ₃ O ₅ , Ti ₄ O. ₇ , Ti ₂ O ₃ , TiO, SnO ₂ , La ₂ Ti ₂ O ₇ , IZO (indium oxide / zinc oxide), AZO (Al-doped ZnO), GZO (Ga-doped ZnO), ATO (Sb-doped SnO), ICO (Indium cerium oxide), ZTO, and WO ₃ are included. The metal oxide or metal sulfide is preferably TiO ₂ , ITO, ZnO, Nb ₂ O ₅ , or ZnS from the viewpoint of refractive index and productivity. The first high-refractive index layer 4 and the second high-refractive index layer 5 may contain only one kind of the metal oxide or metal sulfide, or may contain two or more kinds.

The layer thicknesses of the first high refractive index layer 4 and the second high refractive index layer 5 are preferably set by optical design using an admittance diagram. The layer thicknesses of the first high refractive index layer 4 and the second high refractive index layer 5 are usually preferably 10 to 150 nm, more preferably 20 to 80 nm. When the first high refractive index layer 4 and the second high refractive index layer 5 are 10 nm or more, the first high refractive index layer 4 and the second high refractive index layer 5 cause the reflectance of the transparent conductor 100 to be sufficiently low. Become. On the other hand, if the thicknesses of the first high refractive index layer 4 and the second high refractive index layer 5 are 150 nm or less, the light transmittance of the transparent conductor 100 is unlikely to decrease. The layer thicknesses of the first high refractive index layer 4 and the second high refractive index layer 5 are measured by an ellipsometer.

1.5) First Low Refractive Index Layer and Second Low Refractive Index Layer The transparent conductor 100 of the present invention includes a first low refractive index layer 6 for suppressing plasmon absorption of the underlayer 2 and the transparent metal film 3. And the 2nd low refractive index layer 7 may be arrange | positioned.
The first low refractive index layer 6 and the second low refractive index layer 7 are disposed between the transparent substrate 1 and the base layer 2 or at least one on the transparent metal film 3. Specifically, the first low-refractive index layer 6 and the second low-refractive index layer 7 are either the surface of the base layer 2 on the transparent substrate 1 side or the surface of the transparent metal film 3 on the side not adjacent to the base layer 2. It is disposed on one or both surfaces.

When the first low refractive index layer 6 and the second low refractive index layer 7 are disposed on the surface of the base layer 2 on the transparent substrate 1 side or the surface of the transparent metal film 3 on the side not adjacent to the base layer 2, The reason why the plasmon absorption of the underlayer 2 and the transparent metal film 3 is suppressed is as follows.

If the above-described underlayer 2 and the transparent metal film 3 are regarded as one layer and are composed of metal fine spheres, the localized plasmon absorption cross section C _abs is expressed by the following equation.

Based on the above formula, the lower the refractive index of the layer in contact with the periphery of the underlayer 2 and the transparent metal film 3, the smaller the localized plasmon absorption cross section of the underlayer 2 and the transparent metal film 3. That is, when the first low refractive index layer 6 and the second low refractive index layer 7 having a relatively low refractive index are disposed on the surface of the underlayer 2 or the transparent metal film 3, Plasmon absorption is suppressed.

Here, it is preferable that the first low refractive index layer 6 and the second low refractive index layer 7 include a dielectric material or an oxide semiconductor material having a refractive index of light having a wavelength of 570 nm of less than 1.8. The refractive index is more preferably 1.30 to 1.6, and particularly preferably 1.35 to 1.5. The refractive indexes of the first low refractive index layer 6 and the second low refractive index layer 7 are mainly the refractive indexes of the materials contained in the first low refractive index layer 6 and the second low refractive index layer 7, The density of the low refractive index layer 6 and the second low refractive index layer 7 is adjusted.

Examples of dielectric materials or oxide semiconductor materials included in the first low refractive index layer 6 and the second low refractive index layer 7 include MgF ₂ , SiO ₂ , AlF ₃ , CaF ₂ , CeF ₃ , CdF ₃ , LaF ₃ , Examples include LiF, NaF, NdF ₃ , YF ₃ , YbF ₃ , Ga ₂ O ₃ , LaAlO ₃ , Na ₃ AlF ₆ , Al ₂ O ₃ , MgO, and ThO ₂ . Dielectric material or oxide semiconductor materials among _{_{_{_{others, MgF 2, SiO 2, CaF}}}} 2, CeF 3, LaF 3, LiF, NaF, NdF 3, Na 3 AlF 6, Al 2 O 3, it is MgO and ThO ₂ From the viewpoint that the refractive index is low, MgF ₂ and SiO ₂ are particularly preferable. The first low-refractive index layer 6 and the second low-refractive index layer 7 may contain only one kind of these materials or two or more kinds.

The layer thickness of the first low refractive index layer 6 and the second low refractive index layer 7 is preferably a layer thickness that does not greatly affect the optical characteristics of the transparent conductor 100. The thickness of the first low refractive index layer 6 and the second low refractive index layer 7 is preferably 0.1 to 15 nm, more preferably 1 to 10 nm, and further preferably 3 to 8 nm.

2. Method for Producing Transparent Conductor The method for producing a transparent conductor described above preferably includes the following two steps.
(I) A step of forming a base layer on the transparent substrate by vapor deposition or sputtering (ii) A step of forming a transparent metal film on the base layer by vapor deposition method Further, a layer of a transparent conductor Depending on the configuration, forming the first high refractive index layer, forming the first low refractive index layer, forming the second low refractive index layer, and forming the second high refractive index layer A step may be included.

2.1) Underlayer film formation step The above-described underlayer is formed on a transparent substrate by vapor deposition or sputtering. However, some types of metal cannot be sufficiently deposited. When such a material containing a metal atom is deposited, unevenness may occur in the layer thickness and density of the obtained underlayer. Therefore, when the base layer is formed by an evaporation method, it is preferable that the amount of molybdenum contained in the material is large. The specific content of molybdenum is preferably 20% by mass or more, more preferably 40% by mass or more, and still more preferably 60% by mass or more. A material containing 20% by mass or more of molybdenum is easily formed into a uniform film by an evaporation method. From the viewpoint of cost, it is desirable that the amount of molybdenum is large.

Examples of vapor deposition methods for forming the underlayer include vacuum vapor deposition, electron beam vapor deposition, ion plating, and ion beam vapor deposition. The vapor deposition time is appropriately selected according to the thickness of the underlying layer to be deposited and the deposition rate. The deposition rate is preferably 0.1 to 15 Å / second, more preferably 0.1 to 7 Å / second.

On the other hand, when the underlayer is formed by sputtering, the amount of molybdenum contained in the material is not particularly limited and is appropriately selected according to the composition of the underlayer.

Examples of sputtering methods include ion beam sputtering, magnetron sputtering, reactive sputtering, bipolar sputtering, and bias sputtering. The sputtering time is appropriately selected according to the desired underlayer thickness and film formation rate. The sputter deposition rate is preferably 0.1 to 15 Å / sec, more preferably 0.1 to 14 Å / sec.

2.2) Transparent Metal Film Forming Step A metal is laminated on the above-described underlayer by a vapor deposition method to form a transparent metal film. As described above, by forming a transparent metal film on the underlayer, constituent atoms of the transparent metal film are difficult to migrate, and the surface of the obtained transparent metal film is likely to be smooth.

The method for forming the transparent metal film is not particularly limited as long as it is a general vapor deposition method. For example, a vacuum deposition method, a sputtering method, an ion plating method, a plasma CVD method, a thermal CVD method, or the like is used. Can do.

Among these, the vacuum evaporation method or the sputtering method is preferable. According to the vacuum evaporation method or the sputtering method, a transparent metal film having a uniform and desired film thickness can be easily obtained. The film forming speed of the transparent metal film is appropriately selected according to the type of vapor phase film forming method, the desired film density, and the like.

2.3) Other Steps As described above, in the method for manufacturing a transparent conductor, the first high refractive index layer and the second high refractive index layer are formed in accordance with the layer configuration of the desired transparent conductor. The process and the process of forming the first low refractive index layer and the second low refractive index layer may be included.

The film formation methods of the first high refractive index layer, the second high refractive index layer, the first low refractive index layer, and the second low refractive index layer are not particularly limited as long as they are general vapor deposition methods. , Vacuum deposition, sputtering, ion plating, plasma CVD, thermal CVD, and the like.

3. Regarding the physical properties of the transparent conductor The transparent conductor of the present invention has a light transmittance of 50% or more, preferably 70% or more, and more preferably over the entire range of light within a wavelength range of 400 to 800 nm. 80% or more. When the transmittance is 50% or more in the entire range of the wavelength range of 400 to 800 nm, the transparent conductor is difficult to be colored.
Further, the average transmittance of light within the wavelength range of 400 to 800 nm is preferably 50% or more, more preferably 70% or more, and further preferably 80% or more. When the average transmittance of light in the above-mentioned wavelength range of the transparent conductor is 50% or more, the transparent conductor can be applied to applications that require high transparency.

On the other hand, the average reflectance of light within the wavelength range of 500 to 700 nm of the transparent conductor is preferably 25% or less, preferably 20% or less, more preferably 15% or less, and still more preferably. 10% or less. The transmittance and the reflectance are measured by allowing measurement light to enter the transparent conductor from an angle inclined by 5 ° with respect to the normal of the surface of the transparent conductor. Transmittance and reflectance are measured with a spectrophotometer.

The transparent conductor preferably has a light absorptance of 30% or less, more preferably 15% or less, and even more preferably 10% or less over the entire range of light within a wavelength range of 400 to 800 nm. It is. If the absorptance is 30% or less over the entire range of wavelengths from 400 to 800 nm, the transparent conductor is difficult to be colored.
The average absorptance of light within the wavelength range of 400 to 800 nm is preferably 25% or less, preferably 20% or less, more preferably 15% or less, and further preferably 10% or less. . The light absorption rate of the transparent conductor can be reduced by suppressing the absorption rate of the transparent metal film and the light absorption rate of the material constituting each layer. The absorptance of the transparent conductor is calculated as absorptivity = 100− (transmittance + reflectance).

The a ^* value and b ^* value in the L ^* a ^* b ^* color system of the transparent conductor are preferably within ± 30, more preferably within ± 5, and even more preferably within ± 3.0. Particularly preferably, it is within ± 2.0. If the a ^* value and b ^* value in the L ^* a ^* b ^* color system are within ± 30, the transparent conductor is observed as colorless and transparent. The a ^* value and b ^* value in the L ^* a ^* b ^* color system are measured with a spectrophotometer.

The surface electric resistance value of the transparent conductor is preferably 50Ω / □ or less, more preferably 30Ω / □ or less. A transparent conductor having a surface electric resistance value of 50Ω / □ or less can be applied to a transparent conductive panel for a capacitive touch panel. The surface electrical resistance value of the transparent conductor can be adjusted by the film thickness of the transparent metal film or the like. The surface electrical resistance value of the transparent conductor can be measured according to, for example, JIS K7194, ASTM D257, etc., and can also be measured by a commercially available surface electrical resistivity meter.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited by this.

[Example 1]
A white plate substrate manufactured by Yamanaka Semiconductor (Φ30 mm, thickness 2 mm, refractive index 1.52 of light having a wavelength of 570 nm) was ultrasonically cleaned in ultrapure water (an ultrapure water device Synergy UV manufactured by Millipore). As the ultrasonic cleaner, VS-100III manufactured by ASONE was used. An underlayer and a transparent metal film were formed on the white plate substrate (transparent substrate) by the following method.

(Underlayer)
On the transparent substrate, molybdenum (Mo) was vapor-deposited by resistance heating using a BMC-800T vapor deposition machine manufactured by SYNCHRON Co., Ltd. at 240 A and a film formation rate of 0.1 kg / s. The layer thickness of the underlayer was 0.2 nm. The layer thickness was calculated from the film formation rate and the film formation time.

(Transparent metal film)
On the underlayer, Ag was vapor-deposited by Genetor 1300 (210A resistance heating) manufactured by Optorun to obtain a transparent metal film (film thickness 6 nm) made of Ag. The film formation rate was 3 Å / s. The film thickness is J. A. Woollam Co. Inc. The measurement was made with a VB-250 VASE ellipsometer manufactured by the manufacturer.

[Example 2]
In the manufacture of Example 1, the layer thickness of the underlayer was 2 nm.
Otherwise, a transparent conductor having a transparent substrate / underlayer / transparent metal film in this order was produced in the same manner as in Example 1.

[Example 3]
In the production of Example 1, the thickness of the transparent metal film was 15 nm.
In the production of Example 1, the first high refractive index layer and the second high refractive index layer were formed by the following method.
A transparent conductor having a transparent substrate / first high refractive index layer / underlayer / transparent metal film / second high refractive index layer in this order was produced in the same manner as in Example 1 except for the above.
(First high refractive index layer and second high refractive index layer)
A BMC-800T vapor deposition machine manufactured by SYNCHRON Co., Ltd. was used to deposit TiO ₂ by electron beam (EB) at 320 mA, a deposition rate of 3 Å / s under introduction of oxygen (2 × 10 ⁻² Pa), and a first high refractive index layer ( A layer having a thickness of 37 nm and a light refractive index of 2.35 with a wavelength of 570 nm and a second high refractive index layer (layer thickness of 37 nm and a refractive index of light with a wavelength of 570 nm 2.35) were formed.

[Example 4]
In the production of Example 3, the thickness of the transparent metal film was 9 nm.
Otherwise, a transparent conductor having a transparent substrate / first high refractive index layer / underlayer / transparent metal film / second high refractive index layer in this order was produced in the same manner as in Example 3.

[Example 5]
In the production of Example 3, the thickness of the transparent metal film was 9 nm.
In the production of Example 3, in addition to the first high refractive index layer and the second high refractive index layer, the first low refractive index layer and the second low refractive index layer were formed by the following method.
Except for the above, in the same manner as in Example 3, transparent substrate / first high refractive index layer / first low refractive index layer / underlayer / transparent metal film / second low refractive index layer / second high refractive index layer The transparent conductor which has these in this order was produced.
(First low refractive index layer and second low refractive index layer)
Using a BMC-800T vapor deposition machine manufactured by Syncron Co., SiO ₂ was deposited by electron beam (EB) with oxygen introduction (2 × 10 ⁻² Pa), 100 mA, and a deposition rate of 10 Å / s, and the first low refractive index layer ( A light refractive index of 1.46) having a layer thickness of 5 nm and a wavelength of 370 nm and a second low refractive index layer (layer refractive index of light having a thickness of 5 nm and a wavelength of 370 nm 1.46) were formed.

[Example 6]
In the production of Example 1, the first high refractive index layer, the underlayer, the transparent metal film, and the second high refractive index layer were formed by the following method.
A transparent conductor having a transparent substrate / first high refractive index layer / underlayer / transparent metal film / second high refractive index layer in this order was produced in the same manner as in Example 1 except for the above.
(First high refractive index layer)
Using a sputtering apparatus manufactured by Osaka Vacuum Co., ZnO was RF-sputtered on a transparent substrate at Ar 20 sccm, sputtering pressure 0.1 Pa, room temperature, target-side power 150 W, and deposition rate 1.33 Å / s. The target-substrate distance was 100 mm.
The layer thickness of the obtained first high refractive index layer was 40 nm. The refractive index of light having a wavelength of 570 nm of the first high refractive index layer was 2.05.
(Underlayer)
On the first high-refractive index layer, using a sputtering apparatus manufactured by Osaka Vacuum Co., Mo was sputter-deposited with Ar 20 sccm, sputtering pressure 0.1 Pa, room temperature, target-side power 50 W, and deposition rate 0.33 Å / s. Then, growth nuclei having an average thickness of 0.2 nm were formed. The average thickness of the growth nuclei was calculated from the film formation rate at the nominal value of the manufacturer of the sputtering apparatus.
(Transparent metal film)
Subsequently, Ag was RF-sputtered at Ar 20 sccm, sputtering pressure 0.1 Pa, room temperature, target-side power 150 W, and deposition rate 1.33 Å / s. The target-substrate distance was 100 mm.
The plasmon absorption rate of the obtained transparent metal film made of Ag (film thickness: 9 nm) was 10% or less over the entire wavelength range of 400 to 800 nm (over the entire range).
(Second high refractive index layer)
Using a sputtering apparatus manufactured by Osaka Vacuum Co., ZnO was RF-sputtered on a transparent substrate at Ar 20 sccm, sputtering pressure 0.1 Pa, room temperature, target-side power 150 W, and deposition rate 1.33 Å / s. The target-substrate distance was 100 mm.
The layer thickness of the obtained second high refractive index layer was 40 nm. The refractive index of light having a wavelength of 570 nm of the second high refractive index layer was 2.05.

[Comparative Example 1]
In the production of Example 1, the underlayer was formed by the following method.
Other than that produced the transparent conductor similarly to Example 1. FIG.
(Underlayer)
Al was deposited by resistance heating vapor deposition (RH) at 310 mA and a film formation rate of 5 ｓ / s using a BMC-800T vapor deposition machine manufactured by SYNCHRON Co., Ltd. to obtain an underlayer (layer thickness: 1 nm).

[Comparative Example 2]
In the production of Comparative Example 1, the thickness of the transparent metal film was 10 nm.
Other than that produced the transparent conductor similarly to the comparative example 1. FIG.

[Evaluation]
(Transmissivity and absorption rate of transparent conductor)
The transmissivity and absorptance of light in the wavelength range of 400 to 800 nm of the transparent conductor obtained in each example and comparative example were calculated as follows.
With respect to the obtained transparent conductor, the measurement light is emitted from a position inclined by 5 ° with respect to the normal of the surface of the transparent metal film (or the surface of the second high refractive index layer if the second high refractive index layer is provided on the surface). Incident. And the transmittance | permeability and the reflectance of a transparent conductor were measured with the spectrophotometer (Hitachi High-Tech U4100). Further, the light absorptance was calculated as absorptance = 100− (transmittance + reflectance).
The results are shown in Tables 3 and 3 (graphs of transmittance) and FIG. 4 of graphs (absorbance) together with the layer configuration of each transparent conductor (Tables 1 and 2).

(Surface electrical resistance)
The surface electrical resistances of the transparent conductors obtained in the examples and comparative examples were measured by Loresta EP MCP-T360 manufactured by Mitsubishi Chemical Analytech. The results are shown in Table 3.

[Summary]
As shown in Table 3, in Comparative Example 1 and Comparative Example 2 having a base layer made of Al (particularly Comparative Example 2 has substantially the same configuration as Example 1 of Patent Document 4), it is transparent. The light transmittance of the conductor did not increase, and light absorption could not be sufficiently suppressed. Furthermore, since the surface electrical resistance is high, it is presumed that the surface smoothness of the transparent metal film was low.

On the other hand, in the transparent conductors of Examples 1 to 6 having the underlying layer made of Mo, the average transmittance of light with a wavelength of 400 to 800 nm exceeds 50%, and the average of light within a wavelength of 400 to 800 nm The absorptance was 25% or less, and the surface electrical resistance was also 20Ω / □ or less. This is presumed that a transparent metal film having high surface smoothness was obtained by the underlayer.

In particular, in the transparent conductors of Examples 3 to 6 in which the transparent metal film is sandwiched between the first high refractive index layer and the second high refractive index layer, the average transmittance of light in the wavelength range of 400 to 800 nm is 83. %, And the light transmittance was good.
Further, from the comparison of Examples 4 and 5, in Example 5 in which the first low refractive index layer and the second low refractive index layer were formed, the light transmittance was improved, and the low refractive index layer may be formed. It turned out to be useful.
Further, from the comparison between Examples 4 and 6, it was found that also in Example 6 formed by sputtering, light transmittance was improved, and film formation using sputtering was also useful.

The transparent conductor obtained by the present invention has a low surface electric resistance value and excellent transparency. Therefore, it is preferably used for various types of optoelectronic devices such as various types of displays, touch panels, mobile phones, electronic paper, various types of solar cells, and various types of electroluminescent light control elements.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Underlayer 3 Transparent metal film 4 First high refractive index layer 5 Second high refractive index layer 6 First low refractive index layer 7 Second low refractive index layer 100 Transparent conductor

Claims

A transparent substrate;
An underlayer containing molybdenum and having a layer thickness of 2 nm or less;
A transparent metal film disposed adjacent to the base layer and having a thickness of 15 nm or less;
Transparent conductors including
A high refractive index layer including a dielectric material or an oxide semiconductor material having a higher refractive index of light having a wavelength of 570 nm than that of the transparent substrate is provided between the transparent substrate and the base layer or on the transparent metal film. The transparent conductor according to claim 1, further comprising:
A low refractive index layer containing a dielectric material or an oxide semiconductor material having a refractive index of light having a wavelength of 570 nm of 1.8 or less between at least one of the transparent substrate and the base layer or on the transparent metal film. Furthermore, the transparent conductor of Claim 1 or Claim 2 which has.
A method for producing a transparent conductor comprising a transparent substrate, molybdenum, an underlayer having a layer thickness of 2 nm or less, and a transparent metal film having a film thickness of 15 nm or less in this order,
Forming the underlayer on the transparent substrate by vapor deposition or sputtering;
Forming the transparent metal film on the underlayer by a vapor deposition method;
The manufacturing method of the transparent conductor containing this.