Transparent conductive film

Abstract

Provided is a transparent conductive film that can realize a low resistance value through the retention of a low resistivity even when the film thickness of a transparent electrode layer comprising a conductive oxide is increased.　The transparent conductive film has a transparent electrode layer 40 containing indium oxide and tin oxide formed on a substrate 30. The transparent electrode layer 40 has a film thickness of at least 100 nm. In an analysis of the atomic ratio μ of tin to indium at a total of 11 analysis point locations — composed of an analysis point P1 residing at a depth from the surface of the transparent conductive layer 40 corresponding to 9% to 12% of the thickness of the transparent conductive layer 40, plus analysis points residing at each depth from the analysis point P1 corresponding to 7% to 9% of the thickness of the transparent electrode layer 40 — the maximum analytic value μmax and the analytic value μ1 at the analysis point P1 for the transparent conductive film satisfy the relationship μmax / μ1 ≥ 1.02.

Description

Transparent conductive film

[0001] The present invention relates to a transparent conductive film in which a transparent electrode layer is formed on a flexible substrate.

[0002] Transparent conductive films have traditionally been widely used in touch panels, solar cells, light-control devices, and other devices. However, in recent years, there has been a demand for lower resistance due to the need for larger device areas and faster response times.

[0003] In response to such demands for lower resistance in transparent conductive films, attempts have been made to lower resistance by combining a transparent electrode material made of conductive oxide with a metal material such as a metal mesh of silver or copper, but the use of a metal material in combination with the film sometimes limits its applications due to the deterioration of reliability and durability.

[0004] International Publication No. 2016 / 163323

[0005] In view of the above, increasing the thickness of the transparent electrode layer made of a conductive oxide was considered as a means of reducing the resistance of the transparent conductive film without using a metal material. However, simply increasing the thickness of the transparent electrode layer resulted in an increase in resistivity as the thickness increased, and the expected low resistance value could not be obtained.

[0006] The present invention aims to provide a transparent conductive film that can achieve a low resistance value by maintaining low resistivity even when the film thickness of a transparent electrode layer made of a conductive oxide is increased.

[0007] Specific means for solving the above problems include the following embodiments: <1> A transparent conductive film in which a transparent electrode layer containing indium oxide and tin oxide is formed on a substrate, the transparent electrode layer having a film thickness of 100 nm or more, and an analysis point P located at a depth corresponding to 9 to 12% of the thickness of the transparent electrode layer from the surface of the transparent electrode layer. １ and the analysis point P １ When the atomic ratio μ of tin to indium was analyzed at a total of 11 analysis points, which were analysis points at depths corresponding to 7 to 9% of the thickness of the transparent electrode layer, the maximum analysis value μ ｍａｘand the analysis point P １ Analysis value μ １ But μ ｍａｘ / μ １ ≧1.02. <2> The transparent conductive film according to <1>, wherein the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points where the atomic ratio μ of tin to indium is 0.073 or less is 8 or more. <3> The transparent conductive film according to <2>, wherein there is an analysis point where the atomic ratio μ of tin to indium is 0.073 or more. <4> A transparent conductive film having a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and wherein analysis point P １ and the analysis point P １ <5> A transparent conductive film according to <4>, wherein the atomic ratio μ of tin to indium is greater than 0.073 at any one of the analysis points. <6> A transparent conductive film comprising a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and wherein the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in the thickness direction in a region where impurities originating from the surface and the substrate-side interface of the transparent electrode layer are not detected. <7> A transparent conductive film comprising a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and wherein the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in the thickness direction in a region where impurities originating from the surface of the transparent electrode layer and the interface on the substrate side are not detected. <8> A transparent conductive film comprising a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and wherein the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in the thickness direction in a region where impurities originating from the surface of the transparent electrode layer and the interface on the substrate side are not detected. <9> A transparent conductive film comprising a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and wherein the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in the thickness direction in a region where impurities originating from the surface of the transparent electrode layer and the interface on the substrate side are not detected. <10> A transparent conductive film comprising a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and wherein the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in ｍａｘ and an analysis point P located on the outermost side of the transparent electrode layer. １ Analysis value μ １ But μ ｍａｘ / μ １≧1.02. <7> The transparent conductive film according to <6>, wherein the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points where the value of the atomic ratio μ of tin to indium is 0.073 or less is 8 or more. <8> The transparent conductive film according to <7>, wherein the atomic ratio μ of tin to indium is 0.073 or more at some analysis points. <9> A transparent conductive film having a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and when the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in the thickness direction in a region where impurities originating from the surface and the substrate-side interface of the transparent electrode layer are not detected, the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points where the value of the atomic ratio μ of tin to indium is 0.073 or less is 8 or more. <10> The transparent conductive film according to any one of <1> to <9>, wherein the transparent electrode layer has a region in a thickness direction thereof having a nitrogen content of 0.6 at% or more. <11> The transparent conductive film according to <10>, wherein the transparent electrode layer has a region in a thickness direction thereof on both sides thereof having a nitrogen content of less than 0.6 at%.

[0008] According to the present invention, it is possible to provide a transparent conductive film that can achieve a low resistance value by maintaining low resistivity even when the film thickness of the transparent electrode layer made of a conductive oxide is increased.

[0009] 1 is a graph showing analytical values ​​of the atomic ratio μ of tin to indium in a transparent electrode layer;

[0010] Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

[0011] (Transparent Conductive Film 1) A transparent conductive film 1 as one embodiment of the transparent conductive film of the present invention is formed by laminating a transparent electrode layer 40 on a substrate 30, as shown in FIG.

[0012] (Substrate 30) The substrate 30 can be formed by laminating a functional layer 20 such as a hard coat layer or an optical adjustment layer on one or both surfaces of the transparent resin substrate 10.

[0013] (Transparent Resin Substrate 10) The transparent resin substrate 10 is a substrate that ensures the strength of the transparent conductive film 1. The transparent resin substrate 10 can be a flexible, transparent resin film. Examples of materials for the transparent resin substrate 10 include polyester resin, polyolefin resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include polyethylene, polypropylene, and cycloolefin polymer. Examples of acrylic resins include polymethacrylate. As the material for the transparent resin substrate, polyester resin is preferably used, and PET is more preferably used, from the viewpoints of transparency and strength, for example.

[0014] The surface of the transparent resin substrate 10 may be subjected to a surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

[0015] The thickness of the transparent resin substrate 10 is preferably 10 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more, from the viewpoint of ensuring the strength of the transparent conductive film 1. The thickness of the transparent resin substrate 10 is preferably 500 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less, from the viewpoint of ensuring the handleability of the transparent resin substrate 10 in a roll-to-roll system.

[0016] (Functional Layer 20) The substrate 30 can have a functional layer 20 on one or both sides of the transparent resin substrate 10. The functional layer 20 may be a single layer or multiple layers. A layer that imparts a desired function to the transparent conductive film can be appropriately selected and used as the functional layer 20. Examples of layers that constitute the functional layer 20 include an optical adjustment layer, an anti-reflection layer, an anti-glare layer, an easy-adhesion layer, a stress buffer layer, a hard coat layer, an easy-slip layer, an antistatic layer, a crystallization promotion layer, a crystallization rate adjustment layer, and a coating layer.

[0017] An example of a case where the functional layer 20 is a multi-layer structure is a combination of a hard coat layer and an optical adjustment layer. The hard coat layer may be laminated on at least one side of the transparent resin substrate 10, and may be laminated on both sides as needed. The hard coat layer can impart good chemical resistance and contamination resistance. The optical adjustment layer is a layer that adjusts the optical properties of the transparent conductive film 1 to suppress the pattern visibility of the transparent electrode layer 40 and ensure excellent transparency in the transparent conductive film 1.

[0018] The hard coat layer can be formed, for example, by applying an ultraviolet-curable resin such as an acrylic resin to the surface of the transparent resin substrate 10 and curing it by ultraviolet irradiation. The optical adjustment layer can be formed, for example, by applying a diluted solution of the optical adjustment composition to the surface of the hard coat layer, drying it, and then curing the optical adjustment composition by ultraviolet irradiation.

[0019] (Transparent Electrode Layer 40) The transparent electrode layer 40 is a transparent layer that exhibits excellent conductivity. The transparent electrode layer 40 can be formed on the functional layer 20.

[0020] The transparent electrode layer 40 contains indium oxide and tin oxide. The transparent electrode layer 40 can be formed by sputtering, and an example of a target containing indium oxide and tin oxide that can be used is indium tin oxide (ITO), which is a composite oxide of indium oxide and tin oxide. ITO can impart uniform conductivity to the entire surface of the transparent electrode layer 40, and is preferable from the viewpoint of a balance between transparency and resistance value.

[0021] The amount of tin oxide in ITO is preferably 8% by mass or more, and more preferably 10% by mass or more, based on the total amount of tin oxide and indium oxide, from the viewpoint of low resistivity and film stability. To achieve low resistance through crystallization of ITO, the amount is preferably 20% by mass or less, and more preferably 15% by mass or less. Furthermore, from the viewpoint of improving crystallinity, a portion of the transparent electrode layer may be provided with a loading of 10% by mass or less or 8% by mass or less.

[0022] Materials other than those mentioned above may be combined for the transparent electrode layer 40. Materials to be combined with the transparent electrode layer 40 include, without particular limitation, inorganic materials containing oxides or nitrides of tin, zinc, titanium, aluminum, or the like as components, carbon-based materials such as graphene, carbon nanotubes, fullerene, and diamond-like carbon, and organic transparent conductive materials such as PEDOT, as long as they satisfy the required characteristics of the device.

[0023] The film thickness of the transparent electrode layer 40 is 100 nm or more, preferably 150 nm or more, and more preferably 200 nm or more, from the viewpoint of ensuring high conductivity. On the other hand, from the viewpoint of optical properties and crack resistance, it is preferably 500 nm or less, more preferably 350 nm or less, and particularly preferably 250 nm or less. Therefore, the film thickness of the transparent electrode layer 40 is preferably 100 nm or more and 500 nm or less, more preferably 150 nm or more and 350 nm or less, and particularly preferably 200 nm or more and 250 nm or less. The film thickness of the transparent electrode layer 40 can be measured by cross-sectional observation using, for example, a transmission electron microscope (TEM).

[0024] The transparent electrode layer 40 has an analysis point P 1 at a depth corresponding to 9 to 12% of the thickness of the transparent electrode layer 40 from the surface of the transparent electrode layer 40. １ and the analysis point P １ When the atomic ratio μ of tin to indium was analyzed at a total of 11 analysis points, which were analysis points at depths corresponding to 7 to 9% of the thickness of the transparent electrode layer 40, the maximum analysis value μ ｍａｘ and the analysis point P １ Analysis value μ １ But μｍａｘ / μ １ ≧1.02.

[0025] The 11 analysis points may be arranged at equal intervals in the thickness direction in a region where impurities originating from the surface of the transparent electrode layer 40 and the interface on the substrate side are not detected, thereby eliminating the influence of impurities originating from the surface of the transparent electrode layer 40 and the interface on the substrate side.

[0026] While tin atoms in the transparent electrode contribute to lowering resistance by supplying electrical conductors as a dopant, excess tin atoms cause an increase in resistance. When the transparent electrode is made thicker, there is a tendency for excess tin atoms to be present, particularly on the surface side. In the present invention, the excess tin atoms are concentrated in a limited region in the film, thereby making it possible to keep the concentration of tin atoms in the entire film within an appropriate range. Therefore, the atomic ratio μ of tin to indium near the surface in the film is １ μ with more tin than ｍａｘ From the viewpoint of concentrating excess tin atoms in a limited region in the film, μ １ μ for ｍａｘ The ratio is preferably 1.02 or more.

[0027] It is preferable that the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points at which the atomic ratio μ of tin to indium is 0.073 or less is 8 or more of the total number of analysis points.

[0028] From the viewpoint of sufficiently supplying conduction electrons by the dopant, the atomic ratio μ of tin to indium in the transparent electrode is preferably greater than 0.055 at all analysis points. From the viewpoint of minimizing the region where tin atoms are in excess, the number of analysis points where μ is 0.073 or less is preferably 8 or more, which corresponds to 70% or more of the number of all analysis points. Note that the atomic ratio μ of tin to indium in the transparent electrode is affected by segregation, etc., and therefore generally does not coincide with the amount charged.

[0029] Furthermore, from the viewpoint of concentrating excess tin atoms in a limited region in the film, it is preferable that there is an analysis point where the value of the atomic ratio μ of tin to indium is 0.073 or more.

[0030] The transparent electrode layer 40 can be formed by laminating three layers: a lower layer 40a, an intermediate layer 40b, and a surface layer 40c. The surface layer 40c forms the outermost layer of the transparent electrode layer 40. Note that the transparent electrode layer 40 is not limited to being formed of only the above-described three layers: the lower layer 40a, the intermediate layer 40b, and the surface layer 40c. For example, an additional layer (not shown) for constituting the transparent electrode layer 40 may be provided on the surface of the lower layer 40a facing the substrate 30. The layer disposed on the surface of the lower layer 40a facing the substrate 30 preferably has a film thickness of 10 nm or less.

[0031] The film thickness of the layers other than the transparent electrode layer can be measured by secondary ion mass spectrometry (SIMS). Hereinafter, the film thicknesses other than the transparent electrode layer, i.e., the numerical values ​​of the film thickness of each layer and each region in the transparent electrode layer, represent the numerical values ​​measured by SIMS unless otherwise specified.

[0032] The thickness of the lower layer 40a is preferably 30 nm to 150 nm, more preferably 40 nm to 130 nm, and particularly preferably 50 nm to 120 nm. The thickness of the intermediate layer 40b is preferably 4 nm to 25 nm, more preferably 5 nm to 20 nm, and particularly preferably 6 nm to 15 nm. The thickness of the surface layer 40c is more preferably 30 nm to 150 nm, more preferably 40 nm to 130 nm, and particularly preferably 50 nm to 120 nm.

[0033] It is preferable to adjust the nitrogen content in each layer. The nitrogen content in the lower layer 40a is preferably less than 0.6 at%, and more preferably less than 0.1 at%. The nitrogen content in the intermediate layer 40b is preferably 0.6 at% or more, more preferably 0.6 at% to 15 at% or less, even more preferably 1.0 at% to 10 at% or less, and particularly preferably 1.5 at% to 5 at% or less. The nitrogen content in the surface layer 40c is preferably less than 0.6 at%, and more preferably 0.1 at% or less.

[0034] Thus, the transparent electrode layer 40 preferably has a region in the thickness direction where the nitrogen content is 0.6 at% or more. By forming a layer containing 0.6 at% or more nitrogen, excess tin atoms can be concentrated in a limited area within the film. Furthermore, because the conductivity of the nitrogen-containing layer itself is not high, it is preferable to have regions on both sides of the nitrogen-containing region in the thickness direction where the nitrogen content is less than 0.6 at%.

[0035] The nitrogen concentration in the film of the transparent electrode layer can be measured using a dynamic SIMS under the conditions of a primary ion species of Cs+, a primary ion energy of 2 eV, and a secondary ion polarity of negative, with N as the element of interest, using an ADEPT1010 manufactured by PHI Corporation. An electron gun can be used for charge compensation during measurement.

[0036] (Formation of Transparent Electrode Layer 40) The transparent electrode layer 40 is formed by sputtering using a target containing indium oxide and tin oxide.

[0037] When transparent electrode layer 40 is formed using ITO as a target, the sintered density of ITO is preferably 99% or more from the viewpoint of discharge stability.

[0038] The sputtering system used can be a batch system, a roll-to-roll system, or the like, without any particular limitation, but from the viewpoint of productivity, it is preferable to use a take-up sputtering system and perform the sputtering in a roll-to-roll system. The power source used for sputtering film formation is not particularly limited, and a DC power source, an MF power source, an RF power source, or the like can be used, but from the viewpoint of improving productivity, a DC power source or an MF power source is preferred, and a DC power source is particularly preferred.

[0039] It is known that water molecules are adsorbed in a chamber that is open to the atmosphere. The water molecules in the chamber are taken into the film during the formation of the transparent electrode layer, and can be a factor in increasing the resistance. Therefore, after the film substrate is placed in the sputtering deposition apparatus, it is preferable to evacuate the chamber and reduce the water pressure in the chamber before forming the transparent electrode layer. The water pressure in the chamber is 1×10 －３ Pa or less is preferable, and 1×10 －４Pa or less is more preferable.

[0040] The substrate may be heated or cooled during sputtering depending on the purpose. If the thermal load on the substrate due to sputtering is large, the substrate may be cooled, or sputtering may be performed while heating the substrate in order to improve the film quality of the transparent electrode layer.

[0041] The transparent electrode layer 40 includes at least three layers: a lower layer 40 a, an intermediate layer 40 b, and a surface layer 40 c. When forming multiple layers, sputtering may be performed by repeatedly discharging using the same target, or may be performed by using an apparatus comprising multiple targets and transporting them in a single operation. When an apparatus comprising multiple targets is used, the targets may be placed in separate deposition chambers, which facilitates control of pressure, etc.

[0042] Film formation by sputtering is carried out by introducing argon gas as a carrier gas into a film formation chamber, and further introducing oxygen gas and nitrogen gas as a doping gas. The pressure in the film formation chamber can be adjusted by the amount of carrier gas introduced. The pressure (total pressure) in the film formation chamber is preferably 0.1 Pa to 1.0 Pa, more preferably 0.25 Pa to 0.80 Pa.

[0043] The intermediate layer 40b can be efficiently doped with nitrogen by introducing nitrogen gas into the deposition chamber. The volume ratio of the carrier gas to the nitrogen gas can be controlled using a control device such as a pressure adjusting mechanism and / or a flow rate control mechanism.

[0044] In forming the intermediate layer 40b, the volume ratio of the carrier gas to the nitrogen gas is 250:10 to 250:300, preferably 250:30 to 250:250, more preferably 250:50 to 250:200, and particularly preferably 250:70 to 250:150. The intermediate layer 40b is preferably formed by introducing only the carrier gas and the nitrogen gas into the deposition chamber.

[0045] The transparent electrode layer 40 formed by sputtering is primarily an amorphous layer, but annealing is preferred because it increases the crystallinity, thereby reducing resistivity and improving transmittance. The annealing temperature is preferably 120 to 220°C, and more preferably 130 to 180°C. If the annealing temperature is too low, the time required for crystallization will be long, reducing productivity, while if it is too high, the temperature will exceed the heat resistance temperature of the substrate, making it impossible to maintain the shape of the film.

[0046] (Uses of Transparent Conductive Film) The transparent conductive film of the present invention can be used as a transparent electrode for displays, light-emitting devices, photoelectric conversion devices, and the like.

[0047] Example 1 A 125 μm thick optical PET film (Lumirror, manufactured by Toray Industries, Inc.) was used as a substrate, and a 2 μm thick hard coat layer was formed on both sides of the film using an ultraviolet curable resin (Lioduras TYAB, manufactured by Toyochem Co., Ltd.). The hard coat was formed by applying a UV curable resin coating solution diluted with methyl isobutyl ketone (MIBK) using a bar coater, drying in a hot air drying oven at 80°C for 1 minute, and then irradiating the film with 400 mJ / cm using a high-pressure mercury lamp. ２ This step was carried out on both sides to obtain a film with a hard coat layer, in which a hard coat layer was formed on both sides of the substrate.

[0048] Next, an optical adjustment layer was formed on one side of the hard-coated PET film. A UV-curable resin coating solution for the optical adjustment layer (Lioduras TYZ, manufactured by Toyochem Co., Ltd.) with a refractive index of 1.65 was diluted with MIBK and applied using a bar coater. The coating was dried in a hot air drying oven at 80°C for 1 minute, and then cured by UV irradiation at 600 mJ / cm2 using a high-pressure mercury lamp. The resulting optical adjustment layer had a thickness of 40 nm.

[0049] Subsequently, a transparent electrode layer made of ITO was formed on the optical adjustment layer of the film with the optical adjustment layer by sputtering. After the film with the optical adjustment layer was placed in a roll-to-roll sputtering device, it was transported at room temperature while the water pressure in the chamber was 1×10 －４The chamber was then evacuated to a vacuum of 0.4 Pa. Next, using ITO (tin oxide content 10.0% by mass) as a target, only argon was introduced so that the pressure inside the chamber was 0.4 Pa, and pre-sputtering was performed for 15 minutes at a discharge power of 1.0 kW. After that, while the film was being transported so that the film thickness of the base transparent electrode layer was 6 nm, sputtering was performed using a DC power supply at a discharge power of 0.2 kW, thereby forming a base transparent electrode layer.

[0050] Next, argon and oxygen were supplied at a ratio of 250:3, and under conditions of a chamber pressure of 0.3 Pa, the film was transported so that the film thickness of the first transparent electrode layer was 100 nm, and sputtering was performed using a DC power supply with a discharge power of 1.0 kW to form a first transparent electrode layer.

[0051] Next, only argon and nitrogen were supplied so that the argon:nitrogen ratio was 250:80, and the chamber pressure was 0.5 Pa. While transporting the film so that the thickness of the intermediate layer was 8 nm, sputtering was performed using a DC power supply with a discharge power of 0.2 kW to form an intermediate layer.

[0052] Next, oxygen was supplied to give a ratio of argon:oxygen of 500:3, and under conditions of a chamber pressure of 0.6 Pa, the film was transported so that the film thickness of the second transparent electrode layer was 100 nm, and sputtering was performed using a DC power supply with a discharge power of 1.0 kW to form a second transparent electrode layer.

[0053] The obtained transparent conductive film was further annealed in a hot air drying oven at 140° C. for 90 minutes, and then subjected to various evaluations.

[0054] Example 2 A transparent conductive film was produced in the same manner as in Example 1, except that the film thickness of each of the first transparent electrode layer and the second transparent electrode layer was set to 73 nm.

[0055] Comparative Example 1 A transparent conductive film was produced in the same manner as in Example 1, except that nitrogen was not introduced during the formation of the intermediate layer.

[0056] Comparative Example 2 A transparent conductive film was produced in the same manner as in Example 1, except that the intermediate layer and the first transparent electrode layer were not formed, and the second transparent electrode layer was formed to a film thickness of 200 nm.

[0057] Comparative Example 3 A transparent conductive film was produced in the same manner as in Example 1, except that the intermediate layer and the first transparent electrode layer were not formed, and the second transparent electrode layer was formed to a thickness of 146 nm.

[0058] (Evaluation Methods) The transparent conductive films of Examples 1 and 2 and Comparative Examples 1 to 3 were evaluated by the following evaluation methods.

[0059] The atomic ratio of In to Sn in the transparent electrode layer was measured using an ULVAC-PHI X-ray photoelectron spectroscopy (XPS) analyzer, PHI5000 VersaProbe II, with monochromated Alkα X-rays at 15 kV, 25 W, and a pass energy of 58.70 eV over a 100 μm diameter area. Charge correction was set to 444.5 eV. Thickness analysis of the film was performed by repeatedly sputtering the transparent electrode layer with Ar+ ions accelerated to 2 kV and XPS measurement. Argon etching was performed on approximately 9% of the film thickness per etching, yielding measurement data for 11 points of interest. However, the initial etching was performed by an additional 11% to avoid the influence of surface contamination. Due to the presence of atmospheric contaminants on the outermost surface and the influence of substrate-derived impurities near the substrate interface, the measurement points on the outermost layer and the substrate interface where carbon was detected were not used for analysis. The ratio of the Sn concentration to the In element concentration at the measurement point closest to the surface of the analysis target was calculated to the ratio of the measurement point at which the Sn concentration to the In element concentration was the largest among the measurement points of the analysis target. To determine the measurement points free of impurities, the presence or absence of impurities was first confirmed within a range of 9 to 12% of the thickness of the transparent electrode layer from the surface. If impurities were found to be present, additional etching was performed at an amount of 9% or less of the thickness of the transparent electrode layer per etching. To determine the impurity-free region of the substrate-side interface, the range where impurities exist can be confirmed by preliminary measurements. The etching amount per etching is 9% or less of the film thickness.

[0060] The film thickness of the transparent electrode layer was measured by cross-sectional TEM analysis.

[0061] The sheet resistance of the transparent conductive film was calculated in accordance with JIS K7194 using Loresta GP manufactured by Mitsubishi Chemical Corporation.

[0062]

[0063] As shown in Table 1, it was confirmed that Examples 1 and 2 exhibited good resistivity.

[0064] 2 shows the results of analyzing the atomic ratio μ of tin to indium in the transparent electrode layer at a total of 11 analysis points for Example 1 and Comparative Example 1. The transparent electrode layer of Example 1 had the maximum analytical value μ ｍａｘ and the analysis point P closest to the surface １ Analysis value μ １ μ calculated from ｍａｘ / μ １ is 1.092, and μ ｍａｘ / μ １ On the other hand, in Comparative Example 1, μ ｍａｘ / μ １ was 1.011, which did not satisfy the above relationship.

[0065] The transparent conductive film of the present invention can be suitably used in applications requiring low resistance, such as light control elements, touch sensors, liquid crystal elements, photoelectric conversion elements, heat ray control members, antennas, electromagnetic wave shielding members, and image display devices.

[0066] REFERENCE SIGNS LIST 1 transparent conductive film 10 transparent resin substrate 20 functional layer 30 substrate 40 transparent electrode layer 40a lower layer 40b intermediate layer 40c surface layer

Claims

1. A transparent conductive film in which a transparent electrode layer containing indium oxide and tin oxide is formed on a substrate, the transparent electrode layer having a film thickness of 100 nm or more, and an analysis point P at a depth corresponding to 9 to 12% of the thickness of the transparent electrode layer from the surface of the transparent electrode layer. １ and the analysis point P １ When the atomic ratio μ of tin to indium was analyzed at a total of 11 analysis points, which were analysis points at depths corresponding to 7 to 9% of the thickness of the transparent electrode layer, the maximum analysis value μ ｍａｘ and the analysis point P １ Analysis value μ １ But μ ｍａｘ / μ １ ≧1.

02.

2. The transparent conductive film according to claim 1, wherein the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points where the value of the atomic ratio μ of tin to indium is 0.073 or less is 8 or more.

3. The transparent conductive film according to claim 2, wherein there is an analysis point where the atomic ratio μ of tin to indium is 0.073 or more.

4. A transparent conductive film in which a transparent electrode layer containing indium oxide and tin oxide is formed on a substrate, the transparent electrode layer having a film thickness of 100 nm or more, and an analysis point P at a depth corresponding to 9 to 12% of the thickness of the transparent electrode layer from the surface of the transparent electrode layer. １ and the analysis point P １ a transparent conductive film in which, when the atomic ratio μ of tin to indium is analyzed at a total of 11 analysis points, which are analysis points at depths corresponding to 7 to 9% of the thickness of the transparent electrode layer from 0.055 to 0.073, the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points at which the atomic ratio μ of tin to indium is 0.073 or less is 8 or more.

5. The transparent conductive film according to claim 4, wherein there is an analysis point where the value of the atomic ratio μ of tin to indium is 0.073 or more.

6. A transparent conductive film in which a transparent electrode layer containing indium oxide and tin oxide is formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and when the atomic ratio μ of tin to indium is analyzed at 11 analysis points arranged at equal intervals in the thickness direction in an area where impurities originating from the surface of the transparent electrode layer and the interface on the substrate side are not detected, the maximum analytical value μ ｍａｘ and an analysis point P located on the outermost side of the transparent electrode layer. １ Analysis value μ １ But μ ｍａｘ / μ １ ≧1.

02.

7. The transparent conductive film according to claim 6, wherein the value of the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points where the value of the atomic ratio μ of tin to indium is 0.073 or less is 8 or more.

8. The transparent conductive film according to claim 7, wherein there is an analysis point where the atomic ratio μ of tin to indium is 0.073 or more.

9. A transparent conductive film comprising a transparent electrode layer containing indium oxide and tin oxide formed on a substrate, wherein the transparent electrode layer has a film thickness of 100 nm or more, and when the atomic ratio μ of tin to indium is analyzed at 11 analysis points equally spaced in the thickness direction in an area where impurities originating from the surface of the transparent electrode layer and the interface on the substrate side are not detected, the atomic ratio μ of tin to indium exceeds 0.055 at all analysis points, and the number of analysis points where the atomic ratio μ of tin to indium is 0.073 or less is 8 or more.

10. The transparent conductive film according to any one of claims 1 to 9, wherein the transparent electrode layer has a region in a thickness direction thereof where the nitrogen content is 0.6 at % or more.

11. The transparent conductive film according to claim 10, wherein the region having a nitrogen content of 0.6 at % or more has regions having a nitrogen content of less than 0.6 at % on both sides of the region in the thickness direction.

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