JP2021017640A - Transparent conductor and organic device - Google Patents

Abstract

To provide a transparent conductor excellent in process tolerance by etching, while having high work function and excellent conductivity.SOLUTION: In a transparent conductor 10 including, in this order, a transparent substrate 11, a first metal oxide layer 12, a metal layer 18 containing a silver alloy, and a second metal oxide layer 14, the second metal oxide layer 14 contains ITO, and the ratio (I1/I2) of a peak intensity I1 on (222) plane of ITO to a peak intensity I2 on (440) plane of ITO detected by X-ray diffraction on a surface 14a of the second metal oxide layer 14 is 7.0 or higher.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to transparent conductors and organic devices.

A transparent conductor having both transparency and conductivity is used for various purposes. In recent years, organic devices such as organic EL displays, organic EL lighting, and organic thin-film solar cells are being put into practical use. The organic EL display and the organic EL lighting are configured by laminating a transparent electrode layer (anode), an organic layer, and a reflective electrode layer (cathode) on a transparent substrate such as glass. By applying a voltage between the transparent electrode layer and the reflective electrode layer, a current flows between the electrodes and the organic layer emits light. The light generated in the organic layer passes through the electrodes and is taken out to the outside. Therefore, a transparent electrode is used for at least one of the electrodes.

Patent Document 1 discloses that a laminated structure formed by sandwiching a metal thin film layer of a silver alloy between a pair of transparent refractive index thin film layers is provided on a transparent substrate such as glass. As a material used for the transparent refractive index thin film layer, ITO and the like are mentioned.

In Patent Document 2, an anode having a large work function is used for efficiently injecting holes, and a transparent electrode material layer having a large work function such as ITO is provided. It is disclosed that the charge injection efficiency is enhanced.

Japanese Unexamined Patent Publication No. 2002-15623 Japanese Unexamined Patent Publication No. 2006-324016

Circuits of transparent conductors are usually formed by etching. Here, when ITO (indium tin oxide) is used as the electrode material, the etching rate changes depending on the crystal structure thereof. If the crystallinity of ITO is lowered, etching becomes easier, but if the etching speed is increased, there is a concern that it becomes difficult to secure processing accuracy, especially when forming fine electrodes. Therefore, a transparent conductor having a high work function and excellent processing controllability is considered to be useful in various applications.

Therefore, the present disclosure provides a transparent conductor which has a high work function in one aspect and is excellent in processing accuracy by etching. It is an object of the present disclosure to provide an organic device formed with such a transparent conductor in another aspect.

The transparent conductor according to one aspect of the present disclosure includes a transparent base material, a first metal oxide layer, a metal layer containing a silver alloy, and a second metal oxide layer in this order. The metal oxide layer of 2 contains ITO, and the peak of the (222) plane of ITO with respect to the peak intensity I ₂ of the (440) plane of ITO detected by X-ray diffraction on the surface of the second metal oxide layer. The ratio of strength I ₁ (I ₁ / I ₂ ) is 7.0 or more.

In the second metal oxide layer of the transparent conductor, the work function and the crystallinity of ITO can be enhanced by setting the ratio of the peak intensity I ₂ to the peak intensity I ₁ to 7.0 or more. Since the second metal oxide layer composed of ITO having high crystallinity is provided, the time required for etching the second metal oxide layer can be lengthened. That is, since the etching time can be secured, the etching amount can be precisely controlled. Therefore, the transparent conductor has a high work function and is excellent in processing accuracy by etching.

The transparent conductor may include a third metal oxide layer having a composition different from that of the second metal oxide layer between the metal layer and the second metal oxide layer. Since ITO has a large coefficient of thermal expansion, the compressive stress generated when heated is large, and the transparent conductor tends to warp easily. Therefore, the warp can be reduced by providing the third metal oxide layer.

The third metal oxide layer may contain zinc oxide, indium oxide, tin oxide and titanium oxide. Compounds containing the four components of zinc oxide, indium oxide, tin oxide and titanium oxide tend to form amorphous stable layers. Therefore, the coefficient of thermal expansion is small. Therefore, the warp of the transparent conductor due to heating can be further reduced.

The thickness of the third metal oxide layer may be equal to or greater than the thickness of the second metal oxide layer. As a result, the warp of the transparent conductor due to heating can be further reduced.

The volume resistivity of the second metal oxide layer may be 32 Ω · cm or less. Thereby, the conductivity of the transparent conductor can be improved.

The work function on the surface of the second metal oxide layer may be 5.0 eV or higher. As a result, when an organic layer is provided on the surface of the second metal oxide layer to produce an organic device, holes can be injected into the organic layer or holes can be received from the organic layer smoothly. Can be done. Therefore, the performance of the organic device can be improved.

The size of the ITO crystallite determined from the peak of the (222) plane of ITO contained in the second metal oxide layer may be 15 nm or more. As a result, the processing accuracy by etching can be further improved.

The organic device according to one aspect of the present disclosure comprises any of the above transparent conductors. The above-mentioned transparent conductor has a high work function and can form a circuit by etching with high accuracy. Therefore, it is possible to provide an organic device having high reliability and high efficiency.

According to the present disclosure, it is possible to provide a transparent conductor having a high work function and excellent processing accuracy by etching. It is also possible to provide an organic device formed by using such a transparent conductor.

FIG. 1 is a cross-sectional view schematically showing an embodiment of a transparent conductor. FIG. 2 is a cross-sectional view schematically showing another embodiment of the transparent conductor. FIG. 3 is a cross-sectional view schematically showing still another embodiment of the transparent conductor. FIG. 4 is a diagram schematically showing an embodiment of an organic device. Figure 5 is a work function, which is a graph showing the relationship between the ratio of the peak intensity _{I 2 (I 1 / I 2} ) to the peak intensity _{I 1.}

One embodiment of the present disclosure will be described in detail below with reference to the drawings. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for elements having the same structure or the same function, and duplicate description may be omitted in some cases. Further, unless otherwise specified, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings. Further, the dimensional ratio of each layer is not limited to the ratio shown in the figure.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a transparent conductor. The transparent conductor 10 has a laminated structure in which the transparent base material 11, the first metal oxide layer 12, the metal layer 18, and the second metal oxide layer 14 are arranged in this order.

"Transparent" in the present disclosure means that visible light is transmitted, and light may be scattered to some extent. Regarding the degree of light scattering, the required level differs depending on the use of the transparent conductor 10. Those with light scattering, which is generally referred to as translucent, are also included in the concept of "transparency" herein. The degree of light scattering is preferably small, and the transparency is preferably high. The total light transmittance of the entire transparent conductor 10 is, for example, 60% or more, preferably 65% or more, and more preferably 70% or more. This total light transmittance is a transmittance including diffused transmitted light, which is obtained by using an integrating sphere, and is measured by using a commercially available haze meter.

The transparent base material 11 is not particularly limited, and may be a flexible transparent resin base material. As the transparent resin base material, for example, the organic resin film may be an organic resin sheet. Examples of the transparent base material 11 include polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polycarbonate films, acrylic films, norbornene films, polyarylate films, and polyether sulfone. Examples thereof include films, diacetylcellulose films, polyimides, and triacetylcellulose films. Of these, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferable.

The thickness of the transparent base material 11 is, for example, 200 μm or less from the viewpoint of further increasing the flexibility of the transparent conductor 10. The refractive index of the transparent substrate is, for example, 1.50 to 1.70 from the viewpoint of making the transparent conductor 10 having excellent optical characteristics. The refractive index in the present disclosure is a value measured under the conditions of λ = 633 nm and a temperature of 20 ° C. The transparent base material 11 may be subjected to at least one surface treatment selected from the group consisting of corona discharge treatment, glow discharge treatment, flame treatment, ultraviolet irradiation treatment, electron beam irradiation treatment, and ozone treatment. ..

Since the transparent base material 11 is a transparent resin base material, the transparent conductor 10 can be made excellent in flexibility. As a result, the transparent conductor 10 can be suitably used as a transparent conductor for flexible organic devices.

The first metal oxide layer 12 is a transparent layer containing a metal oxide. The first metal oxide layer 12 has a function of protecting the metal layer 18. The first metal oxide layer 12 may be composed of a metal oxide different from ITO (indium tin oxide).

From the viewpoint of achieving both transparency and corrosion resistance at a higher level, the first metal oxide layer 12 may contain three components of zinc oxide, indium oxide and titanium oxide as main components, and the three components are inevitable. It may be composed of target impurities.

The zinc oxide contained in the first metal oxide layer 12 is, for example, ZnO, and the indium oxide is, for example, In ₂ O ₃ . Titanium oxide is, for example, TiO ₂ . The ratio of the metal atom to the oxygen atom in each of the above metal oxides may deviate from the stoichiometric ratio. It may also contain other oxides having different oxidation numbers. The first metal oxide layer 12 may contain tin oxide, but from the viewpoint of reducing corrosion of the silver alloy contained in the metal layer 18, it is preferable that the content of tin oxide (SnO ₂ ) is small. , It is more preferable that it does not contain tin oxide. The total content of the three components in the first metal oxide layer 12 is preferably 90% by mass or more, preferably 95% by mass or more, in terms of ZnO, In ₂ O ₃ and TiO ₂ , respectively. Is more preferable.

The thickness of the first metal oxide layer 12 is, for example, 60 nm or less from the viewpoint of further improving the transparency. On the other hand, from the viewpoint of further improving corrosion resistance and improving productivity, the thickness is, for example, 5 nm or more.

The first metal oxide layer 12 is zinc oxide, indium oxide and titanium oxide, when converted ZnO, the _In 2 _{O 3} and TiO _2, respectively, ZnO, the ZnO to the total of _In 2 _{O 3} and TiO ₂ The content is preferably 20 to 85 mol%, more preferably 30 to 80 mol%. When converted in the same manner, the content of In ₂ O ₃ with respect to the total of Zn O, In ₂ O ₃ and TiO ₂ is 10 to 35 mol from the viewpoint of improving transparency and achieving both high conductivity and high corrosion resistance. It is preferably%, and more preferably 10 to 25 mol%.

When converted in the same manner, the content of TiO ₂ with respect to the total of ZnO, In ₂ O ₃ and TiO ₂ is preferably 5 to 15 mol% from the viewpoint of achieving both high transparency and excellent corrosion resistance. More preferably, it is ~ 13 mol%.

The first metal oxide layer 12 may have low conductivity or may be an insulator. In this case, the conductivity of the transparent conductor 10 may be borne by the metal layer 18 and the second metal oxide layer 14. The first metal oxide layer 12 can be produced by a vacuum film forming method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a CVD method. Of these, the sputtering method is preferable in that the film forming chamber can be miniaturized and the film forming speed is high. Examples of the sputtering method include DC magnetron sputtering. As the target, a metal target or a metal oxide target can be used. The first metal oxide layer 12 may be a layer that does not dissolve in the acidic etching solution.

The metal layer 18 preferably contains a silver alloy as a main component. The metal layer 18 may be a layer that dissolves in an acidic etching solution. Thereby, patterning can be easily performed. Since the metal layer 18 has high transparency and conductivity, the surface resistance of the transparent conductor 10 can be sufficiently lowered while the visible light transmittance is sufficiently high. Examples of the constituent elements of the silver alloy include Ag and at least one selected from Pd, Cu, Nd, In, Sn, and Sb. Examples of silver alloys include Ag-Pd, Ag-Cu, Ag-Pd-Cu, Ag-Nd-Cu, Ag-In-Sn, and Ag-Sn-Sb. The silver alloy preferably contains Ag as a main component and each of the above-mentioned metals as a sub component. The metal layer 18 may be a layer made of only metal.

The content of the metal other than Ag in the silver alloy is, for example, 0.5 to 5% by mass from the viewpoint of further improving the corrosion resistance and transparency. The silver alloy preferably contains Pd as a metal other than Ag. Thereby, the corrosion resistance in a high temperature and high humidity environment can be further improved.

The thickness of the metal layer 18 may be, for example, 5 to 25 nm. If the thickness of the metal layer 18 becomes too small, the continuity of the metal layer 18 is impaired and the surface resistance value of the transparent conductor 10 tends to increase. On the other hand, if the thickness of the metal layer 18 becomes too large, sufficiently excellent transparency tends to be impaired.

The metal layer 18 has a function of adjusting the conductivity and surface resistance of the transparent conductor 10. The metal layer 18 can be produced by a vacuum film forming method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a CVD method. Of these, the sputtering method is preferable in that the film forming chamber can be miniaturized and the film forming speed is high. Examples of the sputtering method include DC magnetron sputtering. As the target, a metal target can be used.

The second metal oxide layer 14 is a transparent layer containing ITO. The second metal oxide layer 14 has a function of facilitating the movement of holes, for example, when arranged adjacent to the organic layer of the organic device. The second metal oxide layer 14 may be made of ITO.

ITO is an oxide of indium and tin. The oxide is a composite oxide having In, Sn and O (oxygen) as constituent elements. The second metal oxide layer 14 may contain unavoidable impurities as a component other than ITO. The second metal oxide layer 14 containing unavoidable impurities as described above also corresponds to the “second metal oxide layer 14 composed of ITO”.

The work function of the surface 14a of the second metal oxide layer 14 opposite to the metal layer 18 side is preferably 5.0 eV or more, and more preferably 5.1 eV or more. When an organic layer is provided on the surface 14a of the second metal oxide layer 14 having such a high work function to fabricate an organic device, holes are injected into the organic layer or holes from the organic layer are collected. Acceptance can be done smoothly enough. Therefore, the performance of the organic device can be improved. The work function of the surface 14a of the second metal oxide layer 14 can be measured using a commercially available measuring device.

The work function of the surface 14a of the second metal oxide layer 14 tends to depend on the composition in the vicinity of the surface 14a. For example, it can be adjusted by changing the ratio of oxygen atoms in ITO. Specifically, when the second metal oxide layer 14 is formed by DC magnetron sputtering using a target made of an ITO sintered body, the second metal oxide layer 14 is formed by changing the ratio of oxygen gas to the inert gas during sputtering. The crystallinity of ITO constituting the metal oxide layer 14 of the above can be controlled.

The ITO constituting the second metal oxide layer 14 preferably has high crystallinity. By having high crystallinity, the etching time can be secured. As a result, the etching amount can be controlled with a high system, and the processing accuracy by etching can be improved. ITO having a high crystallinity, as well as adjust the percentage of oxygen gas to the inert gas during sputtering, for example, it can be formed by maintaining a low partial pressure of H _{2 O} at DC magnetron sputtering. The partial pressure of H ₂ O, for example, may be less 0.05 Pa, may be not more than 0.01 Pa. The total pressure at this time may be, for example, 0.1 to 1.0 Pa.

The crystallinity of ITO constituting the second metal oxide layer 14 can be confirmed by X-ray diffraction measurement. By performing X-ray diffraction measurement of the surface 14a of the second metal oxide layer 14 using CuKα rays, ITO can be classified into amorphous, crystalline, or microcrystals in between. When ITO is a crystal or a crystallite, a diffraction peak derived from the (222) plane of ITO is usually detected near 2θ = 30 °, and a diffraction peak derived from the (440) plane is detected near 2θ = 50 °. Will be done.

In the present disclosure, the height of the diffraction peak derived from the (222) plane of ITO is the peak intensity I ₁ , and the height of the diffraction peak derived from the (440) plane detected near 2θ = 50 ° is the peak intensity I. _Let it be ₂ . When the peak intensity I ₁ is 500 or more, ITO is classified as "crystal". If the peak intensity I _{1 of the} detected diffraction peak is less than 500, ITO is classified as a "microcrystal". If no peak is detected, ITO is classified as "amorphous". The peak intensity is the intensity measured by the X-ray diffractometer described in the examples.

The size of the ITO crystallites constituting the second metal oxide layer is preferably 12 nm or more, more preferably 15 nm or more. When the size of the crystallite of ITO is large, the processing accuracy of etching can be further improved. The size of the ITO crystallite in the present disclosure is a value obtained from the half width of the peak of the (222) plane detected by the X-ray diffraction measurement.

The ratio (I ₁ / I ₂ ) of the second metal oxide layer 14 in the transparent conductor 10 is 7.0 or more. By increasing this ratio (I ₁ / I ₂ ), the work function of the surface 14a can be increased while increasing the crystallinity of ITO. The work function of the surface 14a may be, for example, 5.0 ev or more, 5.1 eV or more, or 5.2 eV or more.

The volume resistivity of the second metal oxide layer 14 may be, for example, 32 Ω · cm or less, and may be 1 Ω · cm or less. The above ratio (I ₁ / I ₂ ) may be 8.0 or more, or 9.0 or more, from the viewpoint of making all of high crystallinity, high work function, and excellent conductivity higher. There may be. The volume resistivity in the present disclosure is calculated by multiplying the surface resistance value of the ITO single layer measured by the four-terminal method by the thickness of the ITO layer.

The transparent conductor 10 having excellent processing accuracy by etching and having a high work function can be suitably used for various purposes. For example, when used in an organic EL element, the luminous efficiency of the organic EL element can be improved. Further, for example, when used in an organic thin-film solar cell, the power generation efficiency of the organic thin-film solar cell can be improved.

The thickness of the second metal oxide layer 14 may be 2 nm or more, 5 nm or more, or 10 nm or more from the viewpoint of stably increasing the work function on the surface 14a. On the other hand, the thickness of the second metal oxide layer 14 is, for example, 100 nm or less from the viewpoint of sufficiently increasing the transparency and flexibility of the transparent conductor 10.

The thickness of each layer constituting the transparent conductor 10 can be measured by the following procedure. The transparent conductor 10 is cut by a focused ion beam device (FIB, Focused Ion Beam) to obtain a cross section. The cross section is observed using a transmission electron microscope (TEM), and the thickness of each layer is measured. It is preferable that the measurement is performed at 10 or more positions arbitrarily selected and the average value is obtained. As a method for obtaining a cross section, a microtome may be used as a device other than the focused ion beam device. A scanning electron microscope (SEM) may be used as a method for measuring the thickness. It is also possible to measure the film thickness using a fluorescent X-ray apparatus.

The thickness of the transparent conductor 10 may be 210 μm or less, or 200 μm or less. With such a thickness, for example, the required levels of transparency and flexibility can be sufficiently satisfied.

The first metal oxide layer 12 and the second metal oxide layer 14 may be the same in terms of thickness, structure and composition, or may differ from each other in at least one of the thickness, structure and composition. May be good. If the composition of the first metal oxide layer 12 and the composition of the second metal oxide layer 14 are different, only the second metal oxide layer 14 and the metal layer 18 can be subjected to an acidic etching solution in one step. The first metal oxide layer 12 can be left by removing it by etching using it.

The transparent conductor 10 having the above configuration is also excellent in alkali resistance. Therefore, patterning can be performed efficiently. The first metal oxide layer 12, the metal layer 18, and the second metal oxide layer 14 constitute the transparent electrode 20. The transparent conductor 10 provided with the transparent electrode 20 can be suitably used for an organic device such as an organic EL display, an organic EL lighting, and an organic thin film solar cell.

FIG. 2 is a schematic cross-sectional view showing another embodiment of the transparent conductor. In the transparent conductor 10A, the transparent base material 11, the first metal oxide layer 12, the metal layer 18, the third metal oxide layer 16, and the second metal oxide layer 14 are arranged in this order. It has a laminated structure. That is, it differs from the transparent conductor 10 of FIG. 1 in that a third metal oxide layer 16 is provided between the metal layer 18 and the second metal oxide layer 14. The configuration other than the third metal oxide layer 16 is the same as that of the transparent conductor 10.

The first metal oxide layer 12, the metal layer 18, the third metal oxide layer 16 and the second metal oxide layer 14 constitute the transparent electrode 25. For example, when the transparent electrode 25 is arranged adjacent to the organic layer of the organic device with the transparent electrode 25 as an anode, the third metal oxide layer 16 has a function of further smoothing the movement of holes in the transparent electrode 25.

The third metal oxide layer 16 is a metal oxide layer having a composition different from that of the second metal oxide layer 14. For example, it does not have to contain ITO, and may contain four components of zinc oxide, indium oxide, tin oxide and titanium oxide as main components. Further, it may be composed of the four components and unavoidable impurities. The third metal oxide layer 16 containing these four components has sufficiently high conductivity and transparency. Zinc oxide is, for example, ZnO, and indium oxide is, for example, In ₂ O ₃ . Titanium oxide is, for example, TiO ₂ , and tin oxide is, for example, SnO ₂ . The ratio of the metal atom to the oxygen atom in each of the above metal oxides may deviate from the stoichiometric ratio.

The above four components form a more stable phase when they are amorphous than when they are crystalline. That is, an amorphous stable phase is formed on the third metal oxide layer 16. Therefore, the coefficient of thermal expansion is smaller than that of ITO, and the compressive stress generated by heating can be reduced. Therefore, by providing the third metal oxide layer 16 containing four components, the warp of the transparent conductor 10A due to heating can be reduced. The components contained in the third metal oxide layer 16 are not limited to the above four components, and may contain various components having a coefficient of thermal expansion smaller than that of ITO, for example.

When the third metal oxide layer 16 contains the above four components, the content of zinc oxide with respect to the total of the above four components is, for example, 20 mol% from the viewpoint of sufficiently increasing the conductivity while maintaining high transparency. That is all. In the third metal oxide layer 16, the content of zinc oxide with respect to the total of the above four components is, for example, 68 mol% or less from the viewpoint of sufficiently increasing the storage stability in an environment of high temperature and high humidity.

In the third metal oxide layer 16, the content of indium oxide with respect to the total of the above four components is, for example, 35 mol% or less from the viewpoint of keeping the surface resistance sufficiently low and the transmittance within an appropriate range. In the third metal oxide layer 16, the content of indium oxide with respect to the total of the above four components is, for example, 15 mol% or more from the viewpoint of sufficiently increasing the storage stability in an environment of high temperature and high humidity.

In the third metal oxide layer 16, the content of titanium oxide with respect to the total of the above four components is, for example, 20 mol% or less from the viewpoint of ensuring the transmittance of visible light. In the third metal oxide layer 16, the content of titanium oxide with respect to the total of the above four components is, for example, 5 mol% or more from the viewpoint of sufficiently increasing the alkali resistance.

In the third metal oxide layer 16, the content of tin oxide with respect to the total of the above four components is, for example, 40 mol% or less from the viewpoint of ensuring high transparency. In the third metal oxide layer 16, the content of tin oxide with respect to the total of the above four components is, for example, 5 mol% or more from the viewpoint of sufficiently increasing the storage stability in an environment of high temperature and high humidity. The content of each of the above four components is a value obtained by converting zinc oxide, indium oxide, titanium oxide and tin oxide into ZnO, In ₂ O ₃ , TiO ₂ and SnO ₂ , respectively.

The third metal oxide layer 16 may have a composition different from that of the first metal oxide layer 12. Thereby, when the pattern as shown in FIG. 3 is formed by etching, the third metal oxide layer 16 can also be removed by the acidic etching solution together with the second metal oxide layer 14 and the metal layer 18.

The thickness of the third metal oxide layer 16 may be 2 to 200 nm or 5 to 100 nm from the viewpoint of sufficiently exerting its function while maintaining sufficiently high transparency and flexibility. Good. The thickness of the third metal oxide layer 16 may be equal to or greater than the thickness of the second metal oxide layer 14 from the viewpoint of sufficiently reducing the warp of the transparent conductor 10A due to heating, and the thickness of the second metal oxide layer 16 may be equal to or larger than the thickness of the second metal oxide layer 14. It may exceed the thickness of the layer 14.

FIG. 3 is a schematic cross-sectional view showing still another embodiment of the transparent conductor. The transparent conductor 10B has a film-shaped transparent base material 11, a first metal oxide layer 12, a metal layer 18, a third metal oxide layer 16, and a second metal oxide layer 14 in this order. It includes one laminated portion 21, and a second laminated portion 22 having a transparent base material 11 and a first metal oxide layer 12 in this order. The first laminated portion 21 and the second laminated portion 22 are provided adjacent to each other in a direction perpendicular to the stacking direction (vertical direction in FIG. 3) (horizontal direction in FIG. 3). The first laminated portion 21 and the second laminated portion 22 may be provided so as to be arranged alternately along the vertical direction.

The first laminated portion 21 is a conductive portion formed by, for example, a patterning process. The second laminated portion 22 is an insulating portion having no conductor, which is formed by, for example, a patterning process. The transparent conductor 10B can be manufactured by patterning the transparent conductor 10A of FIG. An example of this manufacturing method will be described below.

A photoresist is applied to the surface 14a of the second metal oxide layer 14 of the transparent conductor 10A of FIG. 2 and heated to form a resist film. A part of the resist film is exposed to ultraviolet rays by irradiating the resist film with a photomask having a predetermined pattern. Then, the exposed portion is dissolved and removed using a developing solution to expose a part of the surface 14a of the second metal oxide layer 14 (positive type).

The part of the second metal oxide layer 14 and the third metal oxide layer 16 and the metal layer 18 under the second metal oxide layer 14 are dissolved and removed by using an acidic etching solution. By ensuring the melting time at this time, the accuracy of patterning (processing) can be sufficiently increased. Further, if the composition of the first metal oxide layer 12 is not dissolved in the acidic etching solution, the first metal oxide layer 12 under the metal layer 18 can be left.

After melting the second metal oxide layer 14, the third metal oxide layer 16 and the metal layer 18 to form the second laminated portion 22, the resist film is removed. In this way, the transparent conductor 10B can be obtained. In the above procedure, an example when a positive type photoresist is used has been described, but the present invention is not limited to this, and a negative type photoresist may be used. The same patterning process may be performed using the transparent conductor 10 of FIG. In this case, the first laminated portion serving as the conductive portion is composed of the transparent base material 11, the first metal oxide layer 12, the metal layer 18, and the second metal oxide layer 14. The second laminated portion serving as the insulating portion is composed of the transparent base material 11 and the first metal oxide layer 12.

The method for producing the transparent conductor 10B is not limited to the method using the photoresist described above, and may be, for example, a printing method. In the case of the printing method, ink is applied to a part of the surface 14a of the second metal oxide layer 14 of the transparent conductor 10A of FIG. 2 according to the pattern shape by a method such as inkjet printing, screen printing, or gravure printing. Print. After printing, the portion where the ink is not printed is etched with an acidic etching solution. As a result, the second metal oxide layer 14, the third metal oxide layer 16 and the metal layer 18 are dissolved to form the second laminated portion 22. After that, the transparent conductor 10B can be obtained by removing the ink.

The transparent conductor 10 of FIG. 1, the transparent conductor 10A of FIG. 2, and the transparent conductor 10B of FIG. 3 may have an arbitrary layer between the layers. For example, a hard coat layer may be provided between the transparent base material 11 and the first metal oxide layer 12, or an etching resistant layer may be provided between the metal layer 18 and the first metal oxide layer 12. You may. A water vapor barrier layer may be provided between the transparent base material 11 and the transparent electrodes 20 and 25. The hard coat layers may be provided in pairs so as to sandwich the transparent base material 11. Another metal oxide layer or metal nitride layer having a composition different from that of the first metal oxide layer 12 may be provided between the transparent base material 11 and the first metal oxide layer 12.

The transparent conductors 10, 10A and 10B have high work functions and conductivity, and are excellent in processing accuracy by etching. Therefore, they are used as electrodes for organic devices such as organic EL displays, organic EL lighting, and organic thin-film solar cells. It is preferably used. In this case, the first metal oxide layer 12, the metal layer 18, and the second metal oxide layer 14 function as the transparent electrode 20. Alternatively, the first metal oxide layer 12, the metal layer 18, the third metal oxide layer 16 and the second metal oxide layer 14 function as the transparent electrode 25. The transparent electrodes 20 and 25 may be an anode or a cathode.

FIG. 4 is a diagram schematically showing an embodiment of an organic device. The organic device 100 is, for example, organic EL lighting, and is a laminate having a transparent base material 11, a transparent electrode (anode) 25, a hole transport layer 30, a light emitting layer 40, an electron transport layer 50, and a metal electrode (cathode) 60 in this order. Prepare the body. A transparent conductor 10A can be used as the transparent base material 11 and the transparent electrode 25 in the organic device 100.

The transparent conductor 10A is provided so that the surface of the second metal oxide layer 14 (surface 14a in FIG. 1) of the transparent electrode 20 is in contact with the hole transport layer 30. A power supply 80 is connected to the transparent electrode 25 that functions as an anode and the metal electrode 60 that functions as a cathode. By applying an electric field from the power source 80, holes are injected from the transparent electrode 25 into the hole transport layer 30, and electrons are injected from the metal electrode 60 into the electron transport layer 50.

The holes injected into the hole transport layer 30 and the electrons injected into the electron transport layer 50 recombine in the light emitting layer 40. By this recombination, the organic compound in the light emitting layer 40 emits light. The light generated by this light emission passes through the hole transport layer 30, the transparent electrode 25, and the transparent base material 11, and is emitted from the side surface 20a of the organic device 100.

The organic device 100 uses a transparent conductor 10A as the transparent base material 11 and the transparent electrode 25. Therefore, holes can be efficiently injected from the transparent electrode 25 into the hole transport layer 30. Therefore, the luminous efficiency of the organic device 100 can be increased. Since the work function of the second metal oxide layer 14 contained in the transparent electrode 25 is sufficiently large, the luminous efficiency of the organic device 100 can be sufficiently increased.

The hole transport layer 30, the light emitting layer 40, the electron transport layer 50, and the metal electrode (cathode) 60 can be formed by using ordinary materials. For example, examples of the material of the hole transport layer 30 include aromatic amine compounds. Examples of the light emitting layer 40 include a two-component system in which a host material and a dopant material are combined. Host materials include 1,10-phenanthroline derivatives, organic metal complex compounds, naphthalene, anthracene, naphthalene, perylene, benzofluorantene, naphthofluoranthene and other aromatic hydrocarbon compounds and their derivatives, as well as styrylamine and Examples thereof include tetraaryldiamine derivatives. Examples of the dopant material include a benzodifluolanthene derivative and a coumarin derivative.

The electron transport layer 50 may be formed by using an organic material such as trinitrofluorenone, oxadiazole or a compound having a triazole structure, or an alkali metal such as lithium, lithium fluoride, lithium oxide or the like. It may be formed using an inorganic material. As the metal electrode 60, one composed of a metal material such as aluminum, an organometallic complex or a metal compound can be used. Each layer can be formed by a usual method such as a vacuum vapor deposition method, an ionization vapor deposition method, and a coating method.

Although some embodiments have been described above, the present disclosure is not limited to the above-described embodiments. For example, the organic device of FIG. 4 may have the transparent conductor 10 or the transparent conductor 10B instead of the transparent conductor 10A. Further, the organic device is not limited to the organic EL illumination as shown in FIG. 4, and may be an organic EL display, an organic thin film solar cell, or the like.

The present disclosure will be described in more detail with reference to Examples and Comparative Examples, but the present disclosure is not limited to these Examples.

[Manufacturing of transparent conductor]
(Example 1)
A transparent conductor having a laminated structure as shown in FIG. 1 was produced. The transparent conductor had a laminated structure in which a transparent base material, a first metal oxide layer, a metal layer, and a second metal oxide layer were laminated in this order. This transparent conductor was produced in the following manner.

A commercially available polyethylene naphthalate film (thickness: 100 μm) was prepared. This PEN film was used as a transparent base material. A first metal oxide layer, a metal layer, and a second metal oxide layer were sequentially formed on the transparent substrate by DC magnetron sputtering.

Using a target composed of three components of zinc oxide, indium oxide, and titanium oxide, the first layer was placed on a transparent substrate by DC magnetron sputtering under reduced pressure (0.5 Pa) in a mixed gas atmosphere of argon gas and oxygen gas. 1 metal oxide layer (thickness: 40 nm) was formed. In the first metal oxide layer, when zinc oxide, indium oxide, and titanium oxide are converted into ZnO, In ₂ O ₃ , and TiO ₂ , respectively, the content of ZnO is relative to the total of the above three components. Was 74 mol%, the content of In ₂ O ₃ was 15 mol%, and the content of TiO ₂ was 11 mol%.

Using a target composed of a silver alloy of Ag, Pd and Cu, a metal layer (thickness:) is placed on the first metal oxide layer by DC magnetron sputtering under reduced pressure (0.5 Pa) in an argon gas atmosphere. 10 nm) was formed. The mass ratio of each metal of the silver alloy constituting the metal layer was Ag: Pd: Cu = 99.0: 0.7: 0.3.

A target composed of ITO was set in the chamber of a DC magnetron sputtering apparatus, and a turbo pump was used to sufficiently exhaust the inside of the chamber. After that, the flow of a mixed gas of argon gas and oxygen gas into the chamber was started. DC magnetron sputtering was performed while maintaining the pressure in the chamber at 0.5 Pa and the H ₂ O partial pressure at 0.01 Pa or less. As a result, a second metal oxide layer (thickness: 60 nm) composed of ITO was formed on the metal layer. The flow rate ratio of oxygen gas to argon gas during DC magnetron sputtering was 4.3% by volume. This flow rate ratio is a ratio in a standard state (25 ° C., 1 bar), and is the same in the following Examples, Comparative Examples, and Reference Examples. In this way, a transparent conductor having a laminated structure as shown in FIG. 1 was produced.

(Example 2)
A transparent conductor was produced under the same conditions as in Example 1 except that the flow rate ratio of oxygen gas to argon gas when forming the second metal oxide layer by DC magnetron sputtering was 6.5% by volume.

(Example 3)
A transparent conductor was produced under the same conditions as in Example 1 except that the flow rate ratio of oxygen gas to argon gas when the second metal oxide layer was formed by DC magnetron sputtering was set to 8.7% by volume.

(Example 4)
A transparent conductor was produced under the same conditions as in Example 1 except that the flow rate ratio of oxygen gas to argon gas when forming the second metal oxide layer by DC magnetron sputtering was 10.9% by volume.

(Example 5)
A transparent conductor was produced under the same conditions as in Example 1 except that the flow rate ratio of oxygen gas to argon gas when the second metal oxide layer was formed by DC magnetron sputtering was set to 2.2% by volume.

(Example 6)
A transparent conductor having a laminated structure as shown in FIG. 2 was produced. This transparent conductor has a laminated structure in which a transparent base material, a first metal oxide layer, a metal layer, a third metal oxide layer, and a second metal oxide layer are laminated in this order. Was there. This transparent conductor was produced in the following manner.

The first metal oxide layer and the metal layer were sequentially formed on the transparent substrate by the same procedure as in Example 1. A third metal oxidation composed of four components, zinc oxide, indium oxide, tin oxide and titanium oxide, on a metal layer by DC magnetron sputtering using a ZnO-In ₂ O _3- TiO _2- SnO ₂ target. A material layer (thickness: 30 nm) was formed. The contents of zinc oxide, indium oxide, titanium oxide and tin oxide with respect to the total of the four components were 35 mol%, 29 mol%, 14 mol% and 22 mol%, respectively. This molar ratio is a value obtained by converting each component into ZnO, In ₂ O ₃ , TiO ₂ and SnO ₂ .

Using a target composed of ITO, DC magnetron sputtering was performed under the same conditions as in Example 2 to form a second metal oxide layer (thickness: 30 nm) on the third metal oxide layer. In this way, the transparent conductor of Example 6 was produced.

(Comparative Example 1)
A transparent conductor was produced under the same conditions as in Example 1 except that the flow rate ratio of oxygen gas to argon gas when forming the second metal oxide layer by DC magnetron sputtering was 1.1% by volume.

(Comparative Example 2)
When the second metal oxide layer was formed by DC magnetron sputtering, a transparent conductor was produced under the same conditions as in Example 1 except that oxygen gas was not mixed and only argon gas was used.

(Comparative Example 3)
When forming the second metal oxide layer by DC magnetron sputtering, except that shorter than Example 1 the time of the exhaust in the chamber was increased partial pressure of H _{2 O} during sputtering, Example 1 A transparent conductor was produced under the same conditions as above. That is, the pressure in the chamber during sputtering was 0.5 Pa, which was the same as in Example 1, but the H ₂ O partial pressure exceeded 0.1 Pa.

[Evaluation of transparent conductor]
<Measurement of work function>
The work function on the surface of the second metal oxide layer of the produced transparent conductor was measured using a photoelectron spectrometer (manufactured by RIKEN Keiki Co., Ltd., trade name: FAC-1). The measurement results are shown in the "work function" column of Table 1.

<Measurement of X-ray diffraction>
X-ray diffraction measurement of the surface of the second metal oxide layer was performed. For the measurement, an X-ray diffractometer manufactured by Malvern PANalytical (device name: EMPYREAN, CuKα ray) was used. The range of the measured diffraction angle (2θ) was 20 to 65 °. The height of the diffraction peaks derived from (222) plane of the ITO, which is detected in the vicinity of 2θ = 30 °, and the peak intensity _{I 1.} Further, the height of the diffraction peak derived from the (440) plane of ITO detected near 2θ = 50 ° was defined as the peak intensity I ₂ . Also, the height of the diffraction peaks derived from (400) plane of the ITO, which is detected in the vicinity of 2 [Theta] = 35 ° and the peak intensity _{I 3.} These results are shown in Table 1.

Table 1 shows the ratio of peak intensity I ₁ to peak intensity I ₂ (I ₁ / I ₂ ). Furthermore, the "crystal" as the peak intensity I ₁ is 500 or more, the "microcrystal" of less than the peak intensity I ₁ of those diffraction peak is present 500, classified as "amorphous" and a peak is not detected at all did. These results are shown in the "Crystallinity" column of Table 1. In addition, the size of ITO crystallites was calculated for those classified as "crystals". This result is also shown at the bottom of the "Crystallinity" column in Table 1 (unit: nm). The size of the crystallite of ITO was calculated from the half width of the diffraction peak derived from the (222) plane of ITO by the following formula. In the equation, K is the Scheller constant, λ is the X-ray wavelength, β is the full width at half maximum, and θ is the black angle. Here, K = 0.9.
Crystallite size (nm) = Kλ / βcosθ

<Evaluation of etching controllability>
The transparent conductors of each Example and each Comparative Example were immersed in a salt-iron-based etching solution, and the time for the second metal oxide layer to completely dissolve was measured. When having a third metal oxide layer, the time for the second metal oxide layer and the third metal oxide layer to completely dissolve was measured. When this time was 10 seconds or more, it was judged as "A", when it was 5 to 10 seconds, it was judged as "B", and when it was less than 5 seconds, it was judged as "C". The evaluation results are shown in Table 1. When the crystallinity is low, the time required for dissolution becomes short, and it becomes difficult to precisely control the etching amount.

<Evaluation of volume resistivity>
Metal oxidation composed of ITO on the surface of a commercially available polyethylene terephthalate film (thickness: 125 μm) in the same manner as when the second metal oxide layer of the transparent conductor was prepared in each Example and each Comparative Example. A layer was formed. The volume resistivity of the metal oxide layer thus obtained was measured by using a 4-terminal resistivity meter (trade name: Loresta GP, manufactured by Mitsubishi Chemical Corporation). The volume resistivity was calculated from this surface resistance value and the thickness of the ITO layer. The results are shown in the "Volume resistivity" column of Table 1.

As shown in Table 1, in Comparative Examples 1 to 3, the peak intensities I ₁ / I ₂ were less than 7.0. The peak intensities I ₁ of Comparative Examples 1 to 3 were all 850 or less, confirming that the crystallinity of ITO was low. When ITO was a microcrystal, the evaluation of etching controllability was C.

As shown in Table 1, it was confirmed that the second metal oxide layer in the transparent conductor of each example had a large peak intensity ratio (I ₁ / I ₂ ) and high ITO crystallinity. .. Such ITO, while the flow rate ratio of oxygen gas to the argon gas in a predetermined range, the obtained was confirmed by controlling of H _{2 O} partial pressure in the atmosphere during sputtering. On the other hand, when the flow rate ratio of oxygen gas to the argon gas is too low (Comparative Examples 1 and 2), or, if H _{2 O} partial pressure is high in the atmosphere during sputtering (Comparative Example 3), the crystallinity of ITO is It was confirmed that it decreased.

FIG. 5 is a graph showing the relationship between the two when the ratio of the peak intensity I ₁ to the peak intensity I ₂ (I ₁ / I ₂ ) is taken on the vertical axis and the work function is taken on the horizontal axis. FIG 5, H 2 _O partial pressure is formed under the following conditions 0.01 Pa, and plot the data for Examples 1-5 and Comparative Examples 1-2 The thickness of the second metal oxide layer is common did.

As shown in Table 1 and FIG. 5, it was confirmed that by increasing the above ratio (I ₁ / I ₂ ), a second metal oxide layer having high crystallinity and high work function can be obtained. .. A transparent conductor provided with such a second metal oxide layer has excellent etching controllability. Therefore, the circuit can be formed by etching with high accuracy.

According to the present disclosure, it is possible to provide a transparent conductor capable of forming a circuit by etching with high accuracy while having a high work function. It is also possible to provide an organic device formed by using such a transparent conductor.

10, 10A, 10B ... Transparent conductor, 11 ... Transparent substrate, 12 ... First metal oxide layer, 14 ... Second metal oxide layer, 14a ... Surface, 18 ... Metal layer, 20, 25 ... Transparent Electrodes, 21 ... 1st laminated portion, 22 ... 2nd laminated portion, 30 ... hole transport layer, 40 ... light emitting layer, 50 ... electron transport layer, 60 ... metal electrode, 80 ... power supply, 100 ... organic device.

Claims (8)

A transparent base material, a first metal oxide layer, a metal layer containing a silver alloy, and a second metal oxide layer are provided in this order.
The second metal oxide layer contains ITO and contains
The ratio of the peak intensity I ₁ of the (222) plane of ITO to the peak intensity I ₂ of the (440) plane of ITO detected by X-ray diffraction on the surface of the second metal oxide layer (I ₁ / I). ₂ ) is a transparent conductor of 7.0 or more. The transparent conductor according to claim 1, wherein a third metal oxide layer having a composition different from that of the second metal oxide layer is provided between the metal layer and the second metal oxide layer. .. The transparent conductor according to claim 2, wherein the third metal oxide layer contains zinc oxide, indium oxide, tin oxide and titanium oxide. The transparent conductor according to claim 2 or 3, wherein the thickness of the third metal oxide layer is equal to or greater than the thickness of the second metal oxide layer. The transparent conductor according to any one of claims 1 to 4, wherein the volume resistivity of the second metal oxide layer is 32 Ω · cm or less. The transparent conductor according to any one of claims 1 to 5, wherein the work function on the surface of the second metal oxide layer is 5.0 eV or more. The transparent conductor according to any one of claims 1 to 6, wherein the size of the crystallite of ITO determined from the peak of the (222) plane of ITO contained in the second metal oxide layer is 15 nm or more. .. An organic device comprising the transparent conductor according to any one of claims 1 to 7.

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