JP2000276950A - Transparent conductive thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive thin film having a low resistance, high permeability and low surface toughness. SOLUTION: This transparent conductive thin film is structured by a three layered structure forming a transparent conductive layer 12 of indium tin oxide, a mixed layer 14 of indium tin oxide and metal oxide an a metal oxide layer in this order. Even if a mixing rate of the indium tin oxide and the metal oxide is constant in the mixed layer 14, it may be changed as it is laminated. Because of the existence of the mixed layer 14, an electric resistance of the transparent conductive thin film is lowered, surface toughness on the surface of the thin film can be lowered by having the metal oxide layer of the uppermost layer and by a synergistic effect of the metal oxide layer an the mixed layer 14, and permeability almost equivalent to that of the single ITO(indium tin oxide) layer can be materialized. Even if the transparent conductive thin film is structured by a multi-layered structure formed by alternately laminating the indium tin oxide layer and the metal oxide layer, the transparent conductive thin film having a low resistance and low surface roughness and sufficient permeability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive thin film, for example, an electroluminescent device (hereinafter referred to as EL).
(Referred to as an element).

[0002]

2. Description of the Related Art Since a transparent conductive thin film is transparent and conductive, it is frequently used as a display electrode of a liquid crystal display, an electrode of an organic EL element or an inorganic EL element, and the like. Generally, indium tin oxide (ITO: Indium Tin Oxide) having high transmittance and exhibiting conductivity is used for the transparent conductive thin film.

[0003] However, although it is said that it has conductivity, it generally has higher electric resistance than metal materials such as aluminum and copper used for electrodes and wirings. For example, ITO is used for a transparent electrode of a liquid crystal display device, a display device of an EL element, which is attracting attention as a next-generation display device, and the like. In view of, for example, improving the service life of a transparent electrode, it is desired to reduce the electric resistance of the transparent electrode.

In such an environment, for example, it has been reported that the electric resistance can be reduced by adding vanadium (V) to ITO (the 59th Annual Meeting of the Japan Society of Applied Physics). Preliminary collection 526,1998,9). I
If vanadium is added to TO, the electrical resistance of the transparent conductive layer decreases.

However, due to the addition of vanadium, IT
There is a problem that the crystal grain size of O increases and the surface roughness increases. For example, in an organic EL device or the like in which an anode, an organic layer including a light emitting layer, and a cathode are sequentially formed on a substrate, when the vanadium-added ITO layer is usually used as a transparent anode, the surface of the anode is reduced. When the roughness is large, electric field concentration occurs, the driving durability of the thin film element is impaired, and the life of the element is shortened.

On the other hand, for example, Japanese Patent Application Laid-Open No. 9-063771 discloses that a transparent electrode used as an anode of an organic EL device is made up of an ITO layer and an ITO layer and a metal oxide layer having a higher work function than the ITO. It has been proposed to adopt a layered structure and increase the hole injection efficiency into the organic layer by this configuration. And, as a result of the research of the present applicant, the presence of the metal oxide layer on the uppermost layer of the transparent electrode in this way,
It has been found that the smoothness of the surface of the transparent electrode is enhanced.

[0007]

As described above, as described above, ITO
When the two-layer structure of the layer and the metal oxide layer is used as the transparent electrode of the organic EL device, unlike the case where vanadium is added to ITO, the anode surface can be made flat by the presence of the metal oxide layer. .

However, metal oxides have a resistance of ITO.
Since the metal oxide layer is higher, the electric resistance of the transparent electrode is higher than that of the ITO layer alone. Further, since the metal oxide layer has a low transmittance in the entire visible light range, the thickness of the metal oxide layer must be reduced in order not to deteriorate the transmittance as a transparent conductive thin film.

As described above, to date, no material has been proposed as a transparent electrode material that satisfies all the conditions of low resistance, high transmittance, and low surface roughness.

An object of the present invention is to provide a transparent conductive thin film having low resistance, high transmittance and low surface roughness.

[0011]

In order to achieve the above object, the present invention provides a transparent conductive layer using indium tin oxide, and a metal oxide layer formed on the transparent conductive layer. The transparent conductive thin film further includes a mixed layer containing indium tin oxide and a metal oxide between the metal oxide layer and the transparent conductive layer.

In the present invention, the mixed layer may be a layer in which the indium tin oxide and the metal oxide are mixed at a fixed mixing ratio. Alternatively, the mixed layer may be a layer in which the indium tin oxide and the metal oxide are mixed such that a mixing ratio between the transparent conductive layer and the metal oxide layer changes.

In these transparent conductive thin films, a transparent conductive layer made of indium tin oxide is covered with a metal oxide layer with a mixed layer interposed therebetween. The metal oxide layer has a smooth surface, and the presence of this layer as the uppermost layer of the thin film makes it possible to make the surface roughness of the transparent conductive thin film very small.

Further, since the mixed layer is provided in the middle, even if the metal oxide layer having a high resistance exists in the uppermost layer, a sufficiently low electric resistance can be obtained as a transparent conductive thin film. Furthermore, since there is no problem of electric resistance, the uppermost metal oxide layer can be thinned, and a transmittance comparable to that of a single layer of indium tin oxide can be realized. In addition, since the surface roughness of the transparent conductive thin film can be controlled by controlling the thickness and the mixing ratio of the mixed layer, it is easy to reduce the thickness of the metal oxide layer also in this regard.

Further, if the mixed layer has a structure in which the mixing ratio of indium tin oxide and the metal oxide changes between the transparent conductive layer and the metal oxide layer, the mixed layer and the metal oxide layer are transparent. There is substantially no interface between the conductive layer, that is, between the metal oxide layer and the mixed layer, and between the mixed layer and the transparent conductive layer. Therefore, coloring due to interference at the interface can be prevented, which is suitable for use as a transparent electrode.

Still another feature of the present invention is a transparent conductive thin film containing indium tin oxide and a metal oxide, wherein the indium tin oxide layer and the metal oxide layer are alternately formed. It is to have a laminated multilayer structure.

In the case of such a laminated structure, carriers are emitted from the interface between the transparent conductive layer and the metal oxide layer, particularly from the interface between the indium tin oxide layer and the metal oxide layer. The electric resistance of the entire conductive thin film can be reduced. The release of the carriers is caused by distortion at the interface between the indium tin oxide layer and the metal oxide layer, oxygen vacancies introduced by minute diffusion, and the like, and indium tin oxide near the interface. It is thought to be due to dissolved metal atoms (eg, vanadium atoms). In the present invention, further, since the layers are alternately stacked, crystal growth in the layers is suppressed from each other, so that a smooth thin film surface with low surface roughness can be obtained.

Further, according to the present invention, there is provided an electroluminescent device comprising a transparent electrode, a light emitting layer, and a metal electrode on a substrate, wherein the transparent electrode comprises a transparent conductive layer using indium tin oxide. , A mixed layer containing indium tin oxide and a metal oxide, and a transparent conductive thin film formed by laminating a metal oxide layer in this order. Alternatively, a transparent conductive thin film having a multilayer structure in which the indium tin oxide layers and the metal oxide layers are alternately stacked is used.

When such a transparent conductive thin film is used as a transparent electrode of an electroluminescence element, a transparent electrode having low electric resistance, sufficiently low surface roughness, and sufficient transmittance can be obtained. Therefore, a highly reliable element can be obtained by forming the light emitting layer and the cathode of the element on the transparent electrode.

In the present invention, the metal oxide includes titanium, vanadium, chromium, zirconium,
Any of oxides of molybdenum, ruthenium, tantalum, and tungsten can be used. By controlling the thickness and the mixing ratio of such a metal oxide, the transmittance of the transparent conductive thin film is maintained at the same level as that of indium tin oxide, while lowering the electric resistance and reducing the surface roughness. It is possible.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter, referred to as embodiments) will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows the configuration of a transparent conductive thin film according to Embodiment 1 of the present invention. This thin film has a three-layer structure of a transparent conductive layer 12 of indium tin oxide (hereinafter, ITO), a mixed layer 14 of ITO and metal oxide, and a metal oxide layer 16.

The transparent conductive layer 12 made of indium tin oxide (hereinafter referred to as ITO) is formed to a thickness of 1 to 200 nm on a transparent substrate 10 made of, for example, glass. The mixed layer 14 is formed by mixing ITO and a metal oxide at a ratio of 1 to 99 mol% and having a thickness of 1 to 200 nm. Further, the metal oxide layer 16 is formed by laminating the same metal oxide as the mixed layer 14 to a thickness of 1 to 30 nm.

Metal oxides usable for the mixed layer 14 and the metal oxide layer 16 include titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), molybdenum (Mo), ruthenium (Ru). ), Tantalum (T
a) or an oxide of tungsten (W).

Since the mixed layer 14 formed by adding these metal oxides to ITO at a predetermined ratio has a low electric resistance, the transparent conductive thin film of the present embodiment is made of ITO alone due to the presence of the mixed layer 14. With a higher electrical conductivity than the layer. Further, by controlling the mixing ratio of ITO and metal oxide in the mixed layer 14, the surface roughness of the mixed layer 14 can be controlled, and as a result, the surface roughness of the upper metal oxide layer 16 can be further reduced. it can.

The uppermost metal oxide layer 16 itself has a function of flattening the surface of the transparent conductive thin film, and obtains a very smooth thin film surface by a synergistic effect with the mixed layer 14. be able to.

Further, since the thin film has a low resistance due to the presence of the mixed layer 14, the uppermost metal oxide layer 16 can be thinned, thereby preventing a decrease in transmittance as a transparent conductive thin film. .

Therefore, the transparent conductive thin film can be formed by the above-described IT.
By having a three-layer structure of an O layer, a mixed layer, and a metal oxide layer,
A thin film that satisfies the three conditions of low resistance, low surface roughness, and high transmittance is obtained.

[Embodiment 2] FIG. 2 shows the structure of a transparent conductive thin film according to Embodiment 2 of the present invention. In the first embodiment, the mixed layer is formed of ITO and the metal oxide at a constant mixing ratio, but the mixed layer 2 of the transparent conductive thin film of the second embodiment is formed.
In No. 4, the mixing ratio of ITO and metal oxide changes continuously.

Referring to FIG. 2, a transparent conductive layer 12 using ITO is formed on a transparent substrate 10 such as glass, for example.
Formed on the transparent conductive layer 12 to have a thickness of about 200 nm.
Is formed to a thickness of 1 to 200 nm. At this time, mixed layer 2
No. 4, as shown on the right side of FIG. 2, is formed while continuously changing the composition so that the metal element addition concentration of the metal oxide increases as the layer thickness increases. Then, at the uppermost position of the mixed layer 24, the additive concentration of the metal element is 100%.
%, The metal oxide layer 26 having a thickness of 0.1 to 30 nm is formed continuously with the mixed layer 24.

In the second embodiment, the metal oxides usable for the mixed layer 14 and the metal oxide layer 16 include:
Similarly to the first embodiment, titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), molybdenum (Mo), ruthenium (Ru), tantalum (T)
a) or an oxide of tungsten (W).

As described above, in the second embodiment, the mixed layer 24
Is continuously changed between the transparent conductive layer 12 and the uppermost metal oxide layer 26, that is, between the transparent conductive layer 12 and the mixed layer 24.
And there is no clear interface between the mixed layer and the metal oxide layer 26. Therefore, there is no decrease in transmittance or coloring due to interference at the interface.

Further, similarly to the first embodiment, it is possible to obtain a transparent conductive thin film having a low resistance, a flat thin film surface, and a sufficient transmittance.

Third Embodiment FIG. 3 shows a structure of a transparent conductive thin film according to a third embodiment. The thin film of the third embodiment has a multilayer structure in which ITO layers 32 and metal oxide layers 34 are alternately stacked. For example, an ITO layer 32 having a thickness of 5 to 50 nm and a metal oxide layer 3 having a thickness of 0.5 to 3 nm
The two-layer laminated structure of No. 4 is one set, and two or more n sets, for example, 30 sets are stacked on the transparent substrate 10. At this time, the thin films are stacked such that the uppermost layer of the thin films becomes the metal oxide layer 34.

By forming a transparent conductive thin film with such a laminated structure of the ITO layer and the metal oxide layer, carriers are emitted from the interface between the metal oxide layer 34 and the ITO layer 32. This is thought to be due to the presence of oxygen vacancies introduced by strain or minute diffusion at the interface, and metal atoms (vanadium atoms) dissolved in ITO near the interface. Therefore, the electrical resistance of the transparent conductive thin film is a metal oxide layer,
It becomes lower than the electric resistance in the case of each of the ITO layers alone. In addition, the metal oxide layer 34, which causes a decrease in transmittance in the visible light region, can exhibit its function sufficiently with a very thin layer by adopting a laminated structure. The same transmittance as that of the layer can be realized. Also, ITO / metal oxide / IT
With the layered structure of O /../ metal oxide, each layer is thin, and crystal growth of ITO and metal oxide in each layer is suppressed. Therefore, it is possible to obtain a smooth thin film surface having a small surface roughness.

As in the first and second embodiments, the metal oxide may be titanium (Ti), vanadium (V), chromium (Cr), zirconium (Zr), molybdenum (Mo), ruthenium (Ru). , Tantalum (T
a) or an oxide of tungsten (W) can be used.

Embodiment 4 In Embodiment 4, the transparent conductive thin films according to Embodiments 1 to 3 are used as transparent electrodes of an organic EL device. FIG. 4 shows the configuration of such an organic EL element. As shown in the figure, a transparent electrode 40, an organic compound layer 42 and Mg
A metal electrode 48 is formed of a metal material such as Ag in this order. The organic compound layer 42 has a single-layer structure of an organic light-emitting layer, a two-layer structure of an organic hole transport layer and an organic light-emitting layer, or a three-layer structure of an organic hole transport layer, an organic light-emitting layer, and an organic electron transport layer. 4, and has a two-layer structure of the organic hole transport layer 44 and the organic light emitting layer 46 in the example shown in FIG. In this configuration, a DC current is applied to the organic compound layer 42 using the transparent electrode 40 as an anode and the metal electrode 48 as a cathode, and holes are injected from the anode and electrons are injected from the cathode, so that holes and electrons injected in the light emitting layer are formed. Are recombined, and when the organic light emitting molecule is excited to return to the ground state, fluorescence corresponding to the organic light emitting molecule is obtained.

In the fourth embodiment, the transparent electrode 40 of the organic EL element is the same as that of the first or second embodiment described above.
A transparent conductive thin film having a three-layer structure of O transparent conductive layer / a mixed layer of ITO / metal oxide / metal oxide layer, or a transparent conductive thin film having a multilayered structure of the ITO layer / metal oxide layer according to the third embodiment. Use a thin film. Since the transparent conductive thin film as shown in the first to third embodiments has a high surface smoothness, by using this as the transparent electrode 40, the adhesion between the electrode 40 and the upper organic compound layer 42 is improved. And the life of the element can be extended. In addition, Embodiment 1
Since the transparent conductive thin film of No. 3 has a low electric resistance, if these thin films are used as transparent electrodes, the generation of Joule heat that easily damages the organic layer can be suppressed, and from this viewpoint also contributes to the improvement of the life of the device. Further, since the resistance is low, it is possible to cope with an increase in the size of the organic EL display device or the flat light source. Needless to say, this transparent electrode 40 has a sufficiently high transmittance practically equivalent to that of the ITO single layer.

Further, by selecting a metal oxide material, the anode surface can be covered with a metal oxide having a large work function, the difference from the work function of the hole transport layer 44 becomes small, and the work between the anode and the hole transport layer is reduced. Barriers caused by function differences can be reduced. Therefore, injection of holes from the transparent electrode 40 into the hole transport layer 44 becomes easy, and the device driving voltage can be reduced.

[Embodiment 5] In Embodiment 5, the transparent conductive thin films according to Embodiments 1 to 3 are used as transparent electrodes of an inorganic EL element. FIG. 5 shows the configuration of this inorganic EL element. In the inorganic EL element, unlike the organic EL element described above, an inorganic light emitting material is used for the light emitting layer 52, and the first insulating layer 50 is formed between the inorganic light emitting layer 52 and the transparent electrode 40,
A second insulating layer 54 between the inorganic light emitting layer 52 and the metal electrode 56
To form Then, an AC power supply is connected between the transparent electrode 40 and the metal electrode 56 and an electric field is applied to the inorganic light emitting layer 52 to excite the inorganic light emitting material to emit light.

When the transparent conductive thin film according to the first to third embodiments is used as the transparent electrode 40 of such an inorganic EL element as in the fourth embodiment, the smoothness of the surface of the transparent electrode 40 can be improved. Adhesion with the upper light-emitting layer 52 and the like can be improved, and the life of the element can be extended. In addition, since the electrical resistance of the transparent electrode 40 can be reduced, a larger element such as a larger inorganic EL display device or a flat light source can be manufactured using these thin films as the transparent electrode. .

[Embodiment 6] In the embodiment 6, the transparent conductive thin film according to the above-mentioned embodiments 1 to 3 is formed by an EC (electrochromiform).
c) Used as a transparent electrode of the device. FIG. 6 shows a configuration of an EC anti-glare mirror as an example of the EC element.

As shown in the figure, the EC anti-glare mirror comprises a transparent electrode 40, a first EC layer (WO ₃ ) 60, an insulating layer 62, and a second EC layer (IrO _x ) 6 on a transparent substrate 10 such as glass.
4 and a metal electrode 66. Transparent electrode 40 as anode
A DC power supply is connected between the power supply and the metal electrode 66 serving as a cathode. As a result, charges or H ions are injected into the EC layers 60 and 64 by the action of both electrodes and the insulating layer 62 interposed therebetween, and the colors of the EC layers 60 and 64 change. Then, unnecessary reflected light observed on the transparent substrate 10 side is selectively cut using the change in color.

As the transparent electrodes of the EC element such as the EC anti-glare mirror, the first embodiment is similar to the fourth and fifth embodiments.
By using a transparent conductive thin film such as those described in Nos. 1 to 3, the smoothness of the surface of the transparent electrode 40 can be increased without lowering the transmittance, and the adhesion to the upper EC layer 60 or the like is increased. The service life can be extended. Further, since the electrical resistance of the transparent electrode 40 is reduced, it is possible to manufacture a larger EC element, for example, a large EC anti-glare mirror using these thin films as the transparent electrode.

[0045]

(Example 1) An example of a transparent conductive thin film having a mixed layer having a uniform mixing ratio according to the first embodiment will be described below. The configuration is the same as in FIG. A glass substrate (Corning 7 manufactured by Corning Incorporated) is used as the transparent substrate 10.
059) on the glass substrate 10 with ITO
The transparent conductive layer 12 was formed by laminating the layers. Next, vanadium oxide was used as the metal oxide, and the transparent conductive layer 1 was used.
An ITO mixed layer (homogeneous composition) containing 10% by volume of vanadium oxide was formed as a mixed layer 14 to have a thickness of 20 nm.
Further, on the mixed layer 14, as the metal oxide layer 16,
A vanadium oxide layer was formed to a thickness of nm. These layers 12, 14 and 16 were all formed by using a high-frequency magnetron sputtering method.

[Table 1] The film was formed under the following film forming conditions.

(Example 2) ITO according to Embodiment 3 above
An example of a transparent conductive thin film having a multilayer structure of a metal oxide layer and a metal oxide layer will be described below. The configuration is the same as in FIG. A glass substrate (Corning 7059, manufactured by Corning Incorporated) was used as the transparent substrate 10, and ITO was formed on the glass substrate 10 by high-frequency magnetron sputtering.
A multilayer laminated film of the layer 32 and the vanadium oxide layer 34 was formed. Table 2 below shows the film formation conditions.

[Table 2] As shown in FIG. The ITO layer 3 having a thickness of 10 nm is formed so that the top surface of the transparent conductive thin film becomes the vanadium oxide layer 34.
A pair of vanadium oxide layers 34 each having a thickness of 2 nm and 1 nm was formed, and a total of ten pairs were laminated on the glass substrate 10 so that the ITO layers 32 and the vanadium oxide layers 34 were alternately laminated.

(Comparative Example) As a comparative example, a conventional transparent conductive thin film (a) having a single layer structure of ITO, a transparent conductive thin film (b) having a two-layer structure of ITO / vanadium oxide, and an ITO layer to which vanadium is added in a uniform ratio. A transparent conductive thin film (c) made of Table 3 below shows the film formation conditions.

[Table 3] As shown in FIG.

(Evaluation Results) FIG. 7 shows a transparent conductive thin film of a comparative example [(a) ITO single layer, (b) ITO / vanadium oxide two-layer structure, (c) vanadium-added ITO layer], and a transparent conductive thin film of the present invention. The results of measuring the resistivity of the thin films [(d) Example 1 and (e) Example 2] are shown.
FIG. 8 shows a surface state of the conventional transparent conductive thin film of (a) to (c) by an SEM image. Similarly, FIG. 9 shows a transparent conductive thin film of Example 1 (d) and Example 2 (e). 3 shows a surface state by an SEM image of FIG.

First, the resistivity of each thin film is compared.
The transparent conductive thin film (a) composed of an O-only layer has a resistivity of 3.0.
The transparent conductive thin film (b) as high as 5 × 10 ⁻³ Ω · cm and having a two-layer structure of an ITO layer / a vanadium oxide layer was 3.74.
The resistivity is as high as × 10 ⁻³ Ω · cm. On the other hand, a transparent conductive thin film made of vanadium-doped ITO (c)
Has a low resistivity of 2.33 × 10 ⁻³ Ω · cm.

On the other hand, in the transparent conductive thin film (d) having the three-layer structure of the first embodiment, 2.37 ×
A resistivity as low as 10 ⁻³ Ω · cm has been achieved. Furthermore,
The transparent conductive thin film (e) having a multilayered structure according to the second embodiment includes:
A very low resistivity of 33 × 10 ⁻³ Ω · cm is obtained.

Regarding the smoothness of the surface of each thin film, first, in the case of the conventional (a) to (c), the thin film (b) having the vanadium oxide layer as the uppermost layer has the highest smoothness. The thin film (a) made of ITO alone is inferior to the thin film (b) in smoothness. And the lowest resistance vanadium-doped I
It can be seen that the thin film (c) made of TO has the most unevenness on the surface and the worst smoothness.

On the other hand, the thin film (d) according to Example 1 is somewhat inferior to the thin film (b) having a two-layer structure of ITO / vanadium oxide. However, the smoothness is higher than that of the thin film (c), and is almost the same as that of the thin film (a) of the ITO single layer. In addition, the thin film (e) having the multilayered structure according to the second embodiment has a surface which is equivalent to, or is smoother than, the thin film (a) made of ITO alone. As described above, in the thin film (e), a smooth surface having a low surface roughness is obtained due to the presence of the metal oxide layer on the uppermost layer and the laminated structure as described above. ,
Suppress crystal growth in the metal oxide layer and the ITO layer,
In particular, it is considered that the vanadium oxide layer suppresses the growth of crystal grains in the ITO layer.

(Example 3) Next, as Example 3, a transparent conductive thin film produced by changing the amount of oxygen introduced during the formation of a metal oxide layer, and an organic EL device produced using this transparent conductive thin film Will be described.

On a commercially available glass substrate with ITO, 10% by volume in ITO was deposited by using a high-frequency magnetron sputtering method.
Was formed to a thickness of 10 nm, and a 10 nm-thick vanadium oxide was formed thereon as a metal oxide layer by a high-frequency magnetron sputtering method. The conditions for forming the mixed layer and the metal oxide layer are shown in Table 4 below.

[Table 4] Shown in At the time of vanadium oxide film formation, a sputtering gas having a mixture ratio of oxygen / (argon + oxygen) of 0, 1, 2, 2.5, and 5% by volume was used. Note that pure argon gas was used for producing the mixed layer.

Table 5 shows the sheet resistance, work function, and crystal structure of the vanadium oxide layer obtained by the X-ray diffraction method of the transparent conductive thin film formed by the above method, the ITO previously formed on the substrate, and

[Table 5] Shown in In all samples, the obtained sheet resistance was almost the same as the ITO of the substrate, and the work function was approximately 5.
4 eV, which is larger than that of ITO of the substrate. As the oxygen / (argon + oxygen) mixture ratio in the sputtering gas is increased, the crystal structure of vanadium oxide changes from amorphous to V ₂ O ₅ crystal, and the change is oxygen / (argon + oxygen). The mixing ratio was between 2% and 2.5% by volume. FIG. 10 and FIG. 11 show the prepared transparent conductive thin film and the surface SE of ITO previously formed on the substrate.
An M image is shown. These figures also show that a very smooth surface is obtained when the oxygen / (argon + oxygen) mixture ratio, which is a condition under which V ₂ O ₅ crystallization occurs, is in the vicinity of 2% by volume to 2.5% by volume. I understand.

An organic EL device having a structure as shown in FIG. 12 was prepared using each of the transparent conductive thin films as an anode. A 60-nm triphenylamine pentamer (T
PTE), a 60 nm aluminum quinolinol complex (Alq ₃ ) as a light emitting layer, 0.5 nm lithium fluoride (LiF) as an electron injection layer, and 150 nm aluminum (Al) as a cathode. To form a film.

One of the organic EL devices produced by the above method
Voltage applied to the element at the time of mA driving, luminance 100 cd / m ²
Table 6 below shows the measurement results of the luminous efficiency at the time of and the luminance half-life when driven at a constant current at an initial luminance of 2400 cd / m ² .

[0058]

[Table 6] As shown in this table, all the organic ELs according to Example 3
The device achieves lower voltage driving, higher efficiency, and longer life than the organic EL device using ITO as an anode formed as a comparative example. However, a device in which vanadium oxide is deposited in the vicinity of a mixture ratio of oxygen / (argon + oxygen) of 2 vol% to 2.5 vol%, which is a condition for crystallization of V ₂ O ₅ , is particularly excellent in the above characteristics. An organic EL device was obtained.

[0059]

As described above, the transparent conductive thin film according to the present invention comprises a transparent conductive layer of indium tin oxide,
It has a three-layer structure of a mixed layer of indium tin oxide and metal oxide and a metal oxide layer. Alternatively, a multi-layer structure in which layers of indium tin oxide and layers of metal oxide are alternately stacked is formed. Thereby, it is possible to realize a transparent conductive thin film having a smooth surface with reduced electric resistance without lowering the transmittance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a transparent conductive thin film according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating a configuration of a transparent conductive thin film according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a transparent conductive thin film according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration of an organic EL device according to a fourth embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of an inorganic EL element according to a fifth embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of an electrochromic anti-glare mirror according to Embodiment 6 of the present invention.

FIG. 7 is a diagram comparing the resistivity of a transparent conductive thin film according to a conventional example and the example of the present invention.

FIG. 8 is a diagram showing an SEM image of the surface of a conventional transparent conductive thin film.

FIG. 9 is a diagram showing an SEM image of a surface of a transparent conductive thin film according to an example of the present invention.

FIG. 10 is a diagram showing an SEM image of a surface of a transparent conductive thin film according to an example of the present invention.

FIG. 11 is a diagram showing an SEM image of a surface of a transparent conductive thin film according to an example of the present invention.

FIG. 12 is a view showing a structure of an organic EL device according to an example of the present invention.

[Explanation of symbols]

10 transparent substrate, 12 transparent conductive layer (ITO layer), 1
4,24 mixed layer, 16,26,34 metal oxide layer,
32 ITO layer, 40 transparent electrode, 42 organic compound layer, 44 organic hole transport layer, 46 organic light emitting layer, 48,
56, 66 metal electrode, 50 first insulating layer, 52 inorganic light emitting layer, 54 second insulating layer, 60 first EC layer, 62
Insulating layer, 64 second EC layer.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasukun Taga 41-41, Chuchu, Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture F-term in Toyota Central R & D Laboratories Co., Ltd. 4F100 AA17A AA17B AA17C AA28A AA28B BA03 BA07 BA08 BA10A BA10C GB41 JG01 JG01A JG04 JK14 JN01 JN01A 5G307 FA01 FB01 FC09 FC10

Claims (3)

[Claims] 1. A transparent conductive layer using indium tin oxide, and a metal oxide layer formed as an upper layer, further comprising: a transparent conductive layer between the metal oxide layer and the transparent conductive layer.
A transparent conductive thin film comprising a mixed layer containing indium tin oxide and a metal oxide. 2. The transparent conductive thin film according to claim 1, wherein the mixed layer is formed by mixing the indium tin oxide and the metal oxide at a fixed mixing ratio, or by mixing the transparent conductive layer and the metal oxide. A transparent conductive thin film, wherein the indium tin oxide and the metal oxide are mixed such that a mixing ratio between the indium tin oxide and the metal oxide layer changes. 3. A transparent conductive thin film containing indium tin oxide and a metal oxide, wherein said indium tin oxide layer and said metal oxide layer are alternately laminated, and said metal oxide A transparent conductive thin film having a multilayer structure in which a layer of an object is formed.