JP2003338382A - Organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain occurrence of non-luminescent parts by making film thickness of the organic layer approximately thick in an organic EL element formed by sequentially laminating at least a hole injection layer, a hole transportation layer, a luminescent layer, an electron transportation layer and a negative electrode on a positive electrode. <P>SOLUTION: The positive electrode 20, the hole injection layer 30, the hole transportation layer 30, the luminescent layer 50, the electron transportation layer 60, the negative electrode 80 are sequentially laminated on a substrate 10. The hole injection layer 30 is constituted of a crystalline hole injection layer 31 made of a crystalline organic compound positioning on the positive electrode 20 side and an amorphous hole injection layer 32 made of an amorphous organic compound positioning on the hole injection layer 40 side. The amorphous hole injection layer 32 is thicker than the crystalline hole injection layer 31. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic EL (electroluminescence) device in which at least a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are sequentially laminated on an anode.

[0002]

2. Description of the Related Art Since an organic EL element emits light by itself, it is excellent in visibility and can be driven at a low voltage of several V to several tens of V, so that the weight including a driving circuit can be reduced. Therefore, organic EL
The device is expected to be used as a thin film type display, lighting and backlight.

Further, the organic EL element is also characterized in that it has a wide variety of colors. Another feature is that various colors can be emitted by mixing a plurality of colors.

Such an organic EL device has a structure in which an anode is formed on a substrate, and a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are sequentially stacked on the anode (for example, a layer). See Patent Document 1). Furthermore, an electron injection layer often exists between the electron transport layer and the cathode.

Then, by applying an electric field to the organic layer between the anode and the cathode, electrons move from the cathode and holes move from the anode to the light emitting layer, respectively, and electrons are emitted in the light emitting layer. The holes are recombined, and the energy is emitted from the light emitting layer.

[0006]

[Patent Document 1] Japanese Patent No. 2597377 (page 3,
(Fig. 1)

[0007]

[Problems to be Solved by the Invention] However, organic E
In the L element, since the distance between the electrodes (between the anode and the cathode), that is, the film thickness of the organic layer is about 100 nm, a leak current occurs between the electrodes due to a defect of the substrate or a conductive foreign substance on the substrate. Conducts. As a result, a portion that should emit light, that is, a portion that does not emit light, that is, a non-light emitting portion occurs.

In order to suppress the generation of the non-light emitting portion, it may be considered that the film thickness of the organic layer is increased to alleviate the irregularities due to the above-mentioned defects and foreign matters. However, if the light emitting layer and the hole transport layer and the electron transport layer located on both sides of the light emitting layer are made thicker, the driving voltage rises and conversely the number of non-light emitting portions increases.

Then, it is conceivable to thicken the hole injection layer and the electron injection layer other than the hole transport layer, the light emitting layer and the electron transport layer among the layers interposed between the electrodes. Here, the hole mobility has a mobility about 100 times that of the electron mobility, and since the hole mobility is large especially in the hole injection layer, the voltage increase is the only hole injection layer even if the film thickness is increased. Almost never.

Generally, as the hole injecting layer, a porphyrin compound is used as described in the above-mentioned Patent Document 1. However, since this material is a crystalline organic compound, the film surface increases as the film thickness increases. Unevenness increases, and the electric field concentrates on the convex portion, leading to the generation of a non-light emitting portion.

When an aromatic organic tertiary amine compound, which is an amorphous organic compound, is used for the hole injection layer, the adhesion to the underlying anode is weak and the volume change is particularly large at high temperatures, so The hole injection layer is easily peeled off from the anode below.

Therefore, in view of the above problems, the present invention provides an organic EL device in which at least a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and a cathode are sequentially laminated on an anode to form a film of an organic layer. It is an object of the present invention to appropriately increase the thickness and suppress the generation of non-light emitting portions.

[0013]

In order to achieve the above object, in the invention described in claim 1, on the anode (20),
At least a hole injection layer (30) and a hole transport layer (4
0), the light emitting layer (50), the electron transporting layer (60), the cathode (8
In the organic EL device in which 0) are sequentially stacked, the hole injection layer is a crystalline hole injection layer (31) made of a crystalline organic compound on the anode side and an amorphous organic layer on the hole transport layer side. It is characterized by comprising an amorphous hole injection layer (32) made of a compound, wherein the amorphous hole injection layer is thicker than the crystalline hole injection layer.

According to the present invention, the crystalline hole injection layer is superior in adhesion to the anode than the amorphous hole injection layer, and the amorphous hole injection layer becomes uneven as the film thickness increases as compared with the crystalline hole injection layer. Is utilized because it is difficult to increase.

That is, according to the present invention, the adhesion between the hole injection layer and the anode can be secured by the crystalline hole injection layer, and the unevenness of the film surface can be increased by making the amorphous hole injection layer thicker. The entire hole injection layer can be thickened while suppressing. Therefore, the film thickness of the organic layer can be appropriately increased, and the generation of the non-light emitting portion can be suppressed.

Here, as in the invention described in claim 2,
The thickness of the crystalline hole injection layer (31) is 20 nm or less, and the thickness of the amorphous hole injection layer (32) is 50 nm.
It is preferably at least nm.

The crystalline hole injection layer generally contains many colored substances, and if it is too thick, the color of the crystalline hole injection layer easily affects the emission color of the organic EL device. Further, since the crystalline hole injection layer is crystalline, if it is too thick, irregularities on the film surface increase, electric field concentration is likely to occur, and non-light emitting portions are likely to occur. Due to these restrictions, the thickness of the crystalline hole injection layer is 20
nm or less is preferable.

If the amorphous hole injecting layer is too thin and the film thickness is less than 50 nm, the effect of suppressing the generation of the non-light emitting portion may be insufficient, which is not preferable. Therefore, the film thickness of the crystalline hole injection layer (31) is preferably 20 nm or less, and the film thickness of the amorphous hole injection layer (32) is preferably 50 nm or more.

According to a third aspect of the present invention, the amorphous hole injection layer (3
The film thickness of 2) is 200 nm or less.
This is because if the film thickness of the amorphous hole injection layer is thicker than 200 nm, the driving voltage becomes too high, which is not preferable.

In the material used for the organic EL element, the smaller the ionization potential energy Ip, the larger the hole transporting property, and the larger this Ip, the smaller the hole transporting property. In general, one having a high hole transporting property is used as a hole injection layer and one having a small hole transporting property is used as a hole transporting layer.

In this respect, in the field of organic EL, a material having a difference in Ip from the anode of −0.2 eV or more is generally used.
For example, a material having a difference of −0.1 eV or −0.15 eV is used as the hole injection layer. I between the anode
The difference in p is less than -0.2 eV, for example, the difference is -0.3 eV.
When a material such as V is used for the hole injecting layer, the energy barrier between the anode and the hole injecting layer is large, which causes high voltage.

From such a viewpoint, the hole injection layer in the organic EL device of the present invention also has a difference in Ip between the anode and the anode.
A material of 0.2 eV or more is preferable. This is provided as the invention of claim 4.

That is, according to the fourth aspect of the invention, the value obtained by subtracting the ionization potential energy of the crystalline hole injection layer (31) from the ionization potential energy of the anode (20) and the ionization potential energy of the anode (amorphous hole). Injection layer (32)
The value obtained by subtracting the ionization potential energy of
Both are characterized by being -0.2 eV or more.

According to the fifth aspect of the present invention, the value obtained by subtracting the ionization potential energy of the crystalline hole injection layer (31) from the ionization potential energy of the anode (20) and the ionization potential energy of the anode are calculated to be amorphous. Hole injection layer (32)
The value obtained by subtracting the ionization potential energy of
Both are characterized by being 0 eV or more.

Before forming the hole injecting layer on the anode, it is usual to clean the surface of the anode by UV ozone treatment. After this UV ozone treatment, plasma treatment is further carried out to further improve the surface of the anode. When the cleaning is advanced, the difference in Ip between the anode and the hole injection layer may be 0 eV or more. The present invention can be applied even with such a difference in Ip.

Further, in the invention described in claim 6, in addition to the invention described in claim 4 or 5, the ionization potential energy of the hole transport layer (40) is changed from the ionization potential energy of the crystalline hole injection layer (31). And the amorphous hole injection layer (3
The values obtained by subtracting the ionization potential energy of the hole transport layer from the ionization potential energy of 2) are both in the range of +0.05 to -0.4 eV.

Thus, the hole injection layer (31, 32)
It is preferable to use a material having a difference in Ip of +0.05 to −0.4 eV between and, for example, a material having a difference of −0.1 eV or −0.15 eV for the hole transport layer.

This is because when a material having a difference in Ip between the hole injection layer and the hole injection layer is less than −0.4 eV, for example, a difference of −0.5 eV is used for the hole transport layer, the hole injection layer and the hole transport layer are separated from each other. This is because an energy barrier between them causes a large voltage.

Here, the difference in Ip between the hole injecting layer and the hole transporting layer is -0.4 eV or more, which is compared with the difference in Ip between the anode and the hole injecting layer (-0.2 eV). The reason why the negative range is wide is that the charge transfer between the hole injection layer and the hole transport layer is not the charge transfer between the inorganic material and the organic material, but the charge transfer between the organic material and the organic material. This is because the charge is transferred between them.

The difference in Ip between the crystalline hole injection layer (31) and the amorphous hole injection layer (32) is
Preferably ± 0.2 eV or less, more preferably ± 0.
It is 1 eV or less. This is because if this difference is large, a higher voltage is brought about.

Here, a porphyrin compound can be adopted as the crystalline organic compound forming the crystalline hole injection layer, and specifically, copper phthalocyanine (CuPc) can be adopted as the porphyrin compound. You can Further, as the amorphous organic compound forming the amorphous hole injection layer, an aromatic tertiary amine compound can be adopted.

Further, in order to improve the stability in a high temperature environment, it is necessary to improve the adhesion of the porphyrin compound, especially the adhesion at the interface with the anode. It is considered that this is because the difference in linear expansion coefficient between the two is large. Therefore,
As the crystalline hole injecting layer in contact with the anode, it is preferable to provide a highly crystallized porphyrin-based compound layer having a small morphological change.

Therefore, the inventors of the present invention used CuP, which is a porphyrin compound, as the crystalline hole injection layer in contact with the anode.
When c was adopted, attention was paid to the change in the crystalline state of the CuPc film.

As a result, it was found that the crystal state of the CuPc film was largely different before and after being left in a high temperature environment.
The results of a specific examination of changes in the crystalline state of this CuPc film are shown.

In order to efficiently confirm the change in the crystal state, the temperature of the standing environment was increased to 120 ° C. to accelerate the process, and the standing time was evaluated at 2 hours. Hereinafter, standing under this condition is referred to as accelerated high temperature standing.

After forming an anode made of ITO (oxide of indium-tin) on a glass substrate and subjecting the surface of the anode to plasma treatment with a mixture of argon and oxygen, CuPc was deposited on the anode. CuPc in this case
FIG. 7 shows the results of analyzing the crystalline state of the film by X-ray diffraction before and after the accelerated high temperature standing.

As shown in FIG. 7, in the diffraction peak,
The peak occurring at 2θ = 6.68 ° is derived from the crystal structure of CuPc. In FIG. 7, the solid line in this peak is the peak before the accelerated high temperature standing, that is, the initial peak, and the broken line is the peak after the accelerated high temperature standing, that is, the peak after 120 ° C. for 2 hours. .

The integrated value of this peak value is large,
That is, the higher the peak value, the higher the crystallinity of the CuPc film. In FIG. 7, the peak value (integral value) changes by 1.5 times as much as that before the accelerated high temperature standing at 120 ° C. for 2 hours.

From the above, the present inventors have found that after forming an amorphous hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, a cathode, etc. on a CuPc film which is a crystalline hole injection layer, That is, after the light emitting element is formed, Cu
The fact that the Pc film causes such a change in crystalline state is
It was considered to be the cause of the decrease in adhesion of the uPc film.

That is, it was considered that the adhesion of the CuPc film, particularly the adhesion of the interface with the anode can be improved by forming the CuPc film having crystallinity so that the crystallinity is as high as possible.

As a result of extensive studies, according to the invention of claim 9, at the value of the diffraction peak of copper phthalocyanine (CuPc), which is a porphyrin-based compound, which appears by the X-ray diffraction method, the operating temperature of the organic EL device The amount of change in the diffraction peak due to heating inside is ± 25 of the diffraction peak before heating.
I found that it was good if it was within%.

As described above, the adhesion of the CuPc film can be improved by reducing the change in crystal form of the CuPc film as the crystalline hole injection layer under a high temperature environment. Further, the unevenness of the CuPc film caused by the temperature change can be reduced as much as possible, and the occurrence of short circuit or leak can be suppressed.

As a result of further study, in the organic EL device of the present invention, when Al (aluminum) was used for the cathode, the brightness life was shortened depending on the film thickness of the amorphous hole injection layer. The cause is considered as follows.

In the organic layer under the Al cathode, both interfaces of the amorphous hole injection layer, for example, the interface between the hole transport layer and the amorphous hole injection layer, or the interface between the amorphous hole injection layer and the crystalline hole injection layer. The adhesion of the interface is weak.

Therefore, it is considered that when the stress of the Al cathode and the stress amplified by heat are applied to the interface of these amorphous hole injection layers, the interface peeling occurs. This is considered to be the cause of the reduction in the brightness life.

Therefore, it may be possible to ease the stress from the Al cathode by increasing the film thickness of the amorphous hole injection layer. The study proceeded focusing on the thickness ratio.

As a result, when the ratio B / A of the film thickness B of the amorphous hole injecting layer and the film thickness A of the Al cathode is within a predetermined range, the film thickness of the Al cathode or the film of the amorphous hole injecting layer. It was experimentally found that when the thickness is within a predetermined range, deterioration of the luminance life of the organic EL element is suppressed (see FIGS. 5 and 6).

That is, in the invention described in claim 11,
The cathode (80) is Al, and the ratio B / A between the film thickness B of the amorphous hole injection layer (32) and the film thickness A of the cathode is 0.6 or more.

According to this, further deterioration of the luminance life of the organic EL element can be suppressed.

Here, the upper limit of the ratio B / A can be set to 5.0. This is because, as described above, when the film thickness of the amorphous hole injection layer is thicker than 200 nm, the driving voltage becomes too high, which is not practical. Therefore, the film thickness of the amorphous hole injection layer is preferably 200 nm or less. To do. When the upper limit of the film thickness of the amorphous hole injecting layer is 200 nm, the film thickness of Al in consideration of the driving voltage is 40 nm or more. Therefore, the ratio B / A is 5.
0 is set as the upper limit.

In the thirteenth aspect of the present invention, the cathode (80) is Al, the film thickness thereof is 150 nm or less, and the amorphous hole injection layer (32) has a film thickness of 100 nm or more. It is characterized by being.

In the fourteenth aspect of the present invention, the cathode (80) is Al, the film thickness is 80 nm or less, and the amorphous hole injection layer (32) is 50 nm or more. It is characterized by being.

The inventions according to the thirteenth and fourteenth aspects can further suppress the deterioration of the luminance life of the organic EL element.

The anode (20) is made of indium-
It can be made of tin oxide, so-called ITO.

The reference numerals in parentheses for each means described above are examples showing the correspondence with specific means described in the embodiments described later.

[0056]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described. FIG. 1 is a diagram showing a schematic sectional configuration of an organic EL element S1 according to an embodiment of the present invention.

This organic EL element S1 is provided with a substrate 10 such as glass which is transparent to visible light. Then, on the substrate 10, the anode 20, the hole injection layer 30,
The hole transport layer 40, the light emitting layer 50, the electron transport layer 60, the electron injection layer 70, and the cathode 80 are sequentially stacked.

The anode 20 is formed of a transparent conductive film formed by a sputtering method or the like, and specifically, is formed of an indium-tin oxide (ITO) film or an indium-zinc oxide film. The film thickness is 100 nm to 1
It can be about μm. In this example, the anode 20 is
The ITO film has a thickness of about 150 nm.

A hole injection layer 30 made of a hole injection material is formed on the anode 20. The hole injection layer 30 includes a crystalline hole injection layer 31 and a hole transport layer 40, which are located on the anode 20 side and made of a crystalline organic compound.
The amorphous hole injecting layer 32 is made of an amorphous organic compound located on the side, and the main feature is that the amorphous hole injecting layer 32 is thicker than the crystalline hole injecting layer 31.

In this example, the crystalline hole injection layer 31 is formed as a film made of copper phthalocyanine (CuPc) having a film thickness of 10 nm formed by the vacuum evaporation method, and the amorphous hole injection layer 32 thereon. Is formed as a film of 4,4 ′, 4 ″ -tris (N-bis (p-tert-butylphenyl) amino) triphenylamine having a film thickness of 80 nm formed by a vacuum evaporation method.

Here, copper phthalocyanine is a porphyrin compound, and 4,4 ', 4 "-tris (N-bis (p-tert-butylphenyl) amino) triphenylamine (hereinafter referred to as TBTA) is aromatic. It is a tertiary amine compound.

A hole transport layer 40 is formed on the amorphous hole injection layer 32 of the hole injection layer 30. In this example, the hole transport layer 40 is formed as a film of triphenylamine tetramer having a film thickness of 40 nm formed by a vacuum evaporation method.

A light emitting layer 50 is formed on the hole transport layer 40.
Are formed. The light emitting layer 50 is the hole transport layer 4
0 is formed on the first light emitting layer 51 and the second light emitting layer 52 is formed on the first light emitting layer 51.

In this example, the first light emitting layer 51 is a film in which 5 wt% of rubrene, which is a dopant as a fluorescent dye, is added to triphenylamine tetramer, which is a host, by a vacuum deposition method to have a film thickness of 2 nm. It was formed. Rubrene emits yellow light in the first light emitting layer 51.

The second light emitting layer 52 of this example is a film in which 1 wt% of perylene, which is a fluorescent dye, is added to an adamantane derivative, and is formed to have a film thickness of 40 nm by a vacuum vapor deposition method. In the second light emitting layer 52, blue light is emitted by perylene.

The electron transport layer 6 is formed on the light emitting layer 50.
0 is formed. In this example, the electron transport layer 60 is formed as a film of aluminum quinolate (Alq3) having a film thickness of 20 nm formed by a vacuum evaporation method. In this example, the hole injection layer 30, the hole transport layer 40, the light emitting layer 50, and the electron transport layer 60 are configured as organic layers.

Further, an electron injection layer 70 made of LiF (lithium fluoride) having a film thickness of 0.5 nm and a cathode 80 made of Al (aluminum) having a film thickness of 100 nm are sequentially formed on the electron transport layer 60. ing.

An energy band diagram of the organic EL element S1 of this example is shown in FIG. In FIG. 2, ITO as the anode 20 indicates an ionization potential energy, and LiF as the electron injection layer 70 and the cathode 8 are used.
Al as 0 shows a work function, and the other organic layers 30 to 6
Regarding 0, the upper side of FIG. 2 shows the electron affinity (hereinafter referred to as Ea) and the lower side shows the ionization potential energy (hereinafter referred to as Ip).

Specifically, in FIG. 2, Ip of ITO is 5.0 eV, Ea and Ip of copper phthalocyanine are 3.52 eV and 5.17 eV, respectively, and Ea and Ip of TBTA are 2.45 eV and 5.17 eV, respectively. Ea and Ip of triphenylamine tetramer are 2.40 eV and 5.
40 eV, Ea and Ip of adamantane derivative are 2.61 eV and 5.73 eV, respectively, and Ea and Ip of Alq3 are 2.98 eV, 5.73 eV, LiF and A, respectively.
The work functions of 1 are 2.9 eV and 3.74 eV, respectively.

In such an organic EL element S1,
By applying an electric field between the anode 20 and the cathode 80, electrons move from the cathode 80 and holes move from the anode 20 to the light emitting layer 50, respectively, and the light emitting layer 50 (5
1, 52), the holes and electrons are recombined, and the energy at that time causes the light emitting layer 50 to emit light. That is, the respective dopants in the first and second light emitting layers 51 and 52 emit light, and white light is emitted as a mixed color of yellow and blue.

Specifically, the organic EL device of the present example can obtain a white light emitting device, and the chromaticity of the emitted light is (0.30, 0.3).
It was 5). Such chromaticity is (0.30 ± 0.0
5, 0.35 ± 0.05) white light emitting element is preferable for use in automobile meters and displays.

By the way, in this embodiment, the hole injection layer 30 is replaced by the crystalline hole injection layer 31 located on the anode 20 side.
And the amorphous hole injection layer 32 located on the hole transport layer 40 side, and the amorphous hole injection layer 32 has a unique structure in which it is thicker than the crystalline hole injection layer 31.

This is because in the organic EL element, the thickness of the hole injection layer in which the increase of the driving voltage with the increase of the film thickness is as small as possible is made thicker, and the crystalline hole injection layer is more adhesive to the anode than the amorphous hole injection layer. And that the amorphous hole injecting layer is less likely to have unevenness as the film thickness increases than the crystalline hole injecting layer.

That is, according to the hole injection layer 30 of this embodiment, the crystalline hole injection layer 31 can ensure the adhesion between the hole injection layer 30 and the anode 20, and the amorphous hole injection layer 32 is thicker. By doing so, it is possible to increase the thickness of the hole injection layer 30 while suppressing an increase in the unevenness of the film surface.

Specifically, the film thickness of the crystalline hole injection layer 31 is 10 nm or more (10 nm in this example), and the film thickness of the amorphous hole injection layer 32 is 50 nm or more (8 in this example).
0 nm) and the total thickness of the hole injection layer 30 is 6
The thickness can be increased to 0 to 70 nm or more. Thereby, the total film thickness of the organic layers 30 to 60 can be 150 nm or more (190 nm in this example).

However, the light emitted from the light emitting layer 50 is emitted from the substrate 10.
Since the holes are taken out from the side, it is not preferable to make the hole injection layer 30 (particularly the crystalline hole injection layer 31) too thick because the transmittance of the device is deteriorated. For example, it is preferable to control the thickness of the hole injection layer 30 so that the transmittance of the entire organic layers 30 to 60 in the visible light region can be 80% or more.

As described above, in the present organic EL element S1, the organic layers 30 to 60 can be appropriately thickened. By realizing the thick organic layers 30 to 60, even if there is a defect on the substrate 10 or a conductive foreign substance on the substrate 10, generation of leak current is suppressed and conduction between electrodes is also suppressed. As a result, it is possible to suppress the generation of non-light emitting portions.

Here, the preferable film thickness of the hole injection layer 30 in this embodiment will be described. That is, it is preferable that the film thickness of the crystalline hole injection layer 31 is 20 nm or less and the film thickness of the amorphous hole injection layer 32 is 50 nm or more.

In the organic EL element, the material forming the crystalline hole injection layer 31 is generally a colored substance, and if it is too thick, the color of the crystalline hole injection layer 31 tends to affect the emission color of the organic EL element. In addition, the crystalline hole injection layer 31
Since is crystalline, if it is too thick, irregularities on the film surface increase, electric field concentration is likely to occur, and non-light emitting portions are likely to occur.

Due to these restrictions, the crystalline hole injection layer 31
The film thickness of is preferably 20 nm or less. Further, if the amorphous hole injection layer 32 is too thin and the film thickness is less than 50 nm, the effect of suppressing the generation of the non-light emitting portion may be insufficient, which is not preferable. Therefore, it is preferable that the film thickness of the crystalline hole injection layer 31 is 20 nm or less and the film thickness of the amorphous hole injection layer 32 is 50 nm or more.

Further, the amorphous hole injection layer 32
As for, the film thickness is preferably 200 nm or less. The film thickness 32 of the amorphous hole injection layer is 20
This is because if it is thicker than 0 nm, the driving voltage becomes too high, which is not preferable.

[0082] Specific examples of the effect of suppressing the generation of the non-light emitting portion by (embodiment 1) In the present embodiment, the organic EL element S1 of the present embodiment shown in FIG. 2, 85 ° C., at 500 cd / m ² 1/64
Although the light emission was continued for 1000 hours by the duty driving, no non-light emitting portion was generated in the element S1.

The effect of suppressing the generation of the non-light emitting portion will be described more specifically with reference to the following Comparative Examples 1 to 3.

(Comparative Example 1) As shown in FIG. 2, except that the amorphous hole injecting layer 32 made of TBTA is not provided and only the crystalline hole injecting layer 31 made of copper phthalocyanine is used as the hole injecting layer. An organic EL device similar to the example was produced.

That is, as shown in FIG. 3, the anode 20 is made of ITO, the crystalline hole injection layer 31 is made of copper phthalocyanine having a film thickness of 10 nm, the hole transport layer 40 is made of triphenylamine tetramer having a film thickness of 40 nm, and the first The light emitting layer 51 has a film thickness of 2 nm.
Of triphenylamine tetramer + rubrene, the second light-emitting layer 52 is formed of an adamantane derivative having a thickness of 40 nm + perylene,
The electron transport layer 60 has a thickness of 20 nm of Alq3, the electron injection layer 70 has a thickness of 0.5 nm of LiF, and the cathode 80 has a thickness of 100.
The Al layer has a laminated structure of Al.

This organic EL element is a white light emitting element,
The chromaticity of the emission color was (0.32, 0.36). When this device continued to emit light at 85 ° C. and 500 cd / m ² at a 1/64 duty drive, a non-light emitting part was generated in the device in 500 hours. This is because the hole injection layer 31 is 10
It is considered that since only copper phthalocyanine having a small thickness of nm was used, the entire organic layer was thinned and a short circuit easily occurred between the electrodes.

(Comparative Example 2) The hole injection layer was made of TB without providing the crystalline hole injection layer 31 made of copper phthalocyanine.
An organic EL device similar to the example shown in FIG. 2 was manufactured except that only the amorphous hole injection layer 32 made of TA was used.

That is, as shown in FIG. 4, the anode 20 is made of ITO, and the amorphous hole injection layer 32 is made to have a film thickness of 80 n.
m TBTA, the hole transport layer 40 is a triphenylamine tetramer having a thickness of 40 nm, and the first light emitting layer 51 is a thickness of 2 nm.
Of triphenylamine tetramer + rubrene, the second light-emitting layer 52 is formed of an adamantane derivative having a thickness of 40 nm + perylene,
The electron transport layer 60 has a thickness of 20 nm of Alq3, the electron injection layer 70 has a thickness of 0.5 nm of LiF, and the cathode 80 has a thickness of 100.
The Al layer has a laminated structure of Al.

This organic EL element is a white light emitting element,
The chromaticity of the emitted color was (0.31, 0.36). When this device continued to emit light at 85 ° C. and 500 cd / m ² by 1/64 duty driving, the whole device became a non-light emitting part in 100 hours.

This is because the adhesion between ITO as the anode and TBTA as the amorphous organic compound is poor.
It is considered that peeling occurred at the interface between ITO and TBTA during the durability test.

(Comparative Example 3) Similar to Comparative Example 1 shown in FIG. 3, the amorphous hole injection layer 32 made of TBTA is used.
Is not provided, the hole injection layer is made up of only the crystalline hole injection layer 31 made of copper phthalocyanine, and in this Comparative Example 3, the thickness of the crystalline hole injection layer 31 is 90%.
thickened to nm.

That is, as shown in FIG.
0 is ITO, the crystalline hole injection layer 31 is 90 nm thick copper phthalocyanine, the hole transport layer 40 is 40 nm thick triphenylamine tetramer, and the first light emitting layer 51 is 2 nm thick.
nm triphenylamine tetramer + rubrene, the second light-emitting layer 52 is a 40-nm-thick adamantane derivative + perylene, the electron-transporting layer 60 is 20-nm-thick Alq3, and the electron-injection layer 70 is 0.5-nm-thick LiF. , The thickness of the cathode 80 is 1
The laminated structure was made of Al having a thickness of 00 nm.

The emission color of this organic EL device was bluish white, and the chromaticity of the emission color was (0.20, 0.22).
It is considered that this is because the copper phthalocyanine, which is a blue film, was thickened. As described above, the crystalline hole injection layer generally has many colored substances, and from such a viewpoint, there are many restrictions in thickening only the crystalline hole injection layer.

Further, this element was tested at 85 ° C. and 500 cd / m
^After continuing to emit light with 1/64 duty drive at ² ,
A non-light emitting portion was generated in the device in 300 hours. this is,
It is considered that the thickening of the crystalline organic compound copper phthalocyanine increased the unevenness of the film surface and concentrated the electric field on the raised parts, which led to the generation of the non-light emitting part.

Due to these restrictions, the thickness of the crystalline hole injection layer 31 is preferably 20 nm or less as described above.
By the way, according to the study by the present inventor, when the crystalline hole injection layer 31 made of copper phthalocyanine is thicker than 20 nm, the emission color of the organic EL element becomes bluish, and moreover, it is emitted by the same duty driving as described above. I continued to do, 300
A non-light emitting portion was generated in the element in time.

From these experimental studies, the thickness of the crystalline hole injection layer 31 is preferably 20 nm or less, more preferably 15 nm or less.

Compared with these comparative examples, in the organic EL element S1 of this embodiment, the hole injecting layer 30 is a combination of a crystalline compound and an amorphous compound. It can be seen that the film thickness can be appropriately increased and the generation of the non-light emitting portion can be suppressed.

Further, in the present embodiment, the hole injection layer 30 is changed from the Ip of the anode 20 to the Ip of the hole injection layer 30.
It is preferable to use a material having a value obtained by subtracting −0.2 eV or more. That is, the value obtained by subtracting the Ip of the crystalline hole injection layer 31 from the Ip of the anode 20 and the anode 20
It is preferable that the values obtained by subtracting Ip of the amorphous hole injecting layer 32 from Ip of 2 are both −0.2 eV or more. This is for the following reason.

In the material used for the organic EL device,
The smaller the ionization potential energy Ip, the larger the hole transport property, and the larger this Ip, the smaller the hole transport property. A hole transport layer having a high hole transport property and a hole transport layer having a low hole transport property are used.

In this regard, in the field of organic EL, materials having an Ip difference of −0.2 eV or more with the anode are generally used.
For example, a material having a difference of −0.1 eV or −0.15 eV is used as the hole injection layer. I between the anode
The difference in p is less than -0.2 eV, for example, the difference is -0.3 eV.
When a material such as V is used for the hole injecting layer, the energy barrier between the anode and the hole injecting layer is large, which causes high voltage.

From such a viewpoint, the hole injection layers 31 and 32 of this embodiment also have a difference in Ip from the anode 20 of −.
A material of 0.2 eV or more is preferable.

This means that in FIG.
It is illustrated that the value obtained by subtracting Ip of the hole injection layers 31 and 32 from p is −0.17 eV. In addition,
In FIG. 2, from the Ip of the anode 20 to the Ip of the hole transport layer 40.
The value obtained by subtracting is −0.4 eV, which is less than −0.2 eV.

Further, from the Ip of the anode 20, the hole injection layer 3 is formed.
The value obtained by subtracting Ip of 1, 32 may be 0 eV or more. Before forming the hole injection layers 31 and 32 on the anode 20, it is usual to clean the surface of the anode 20 by UV ozone treatment. After this UV ozone treatment, plasma treatment is further performed to further improve the anode. If the surface of the anode 20 is cleaned, the Ip between the anode 20 and the hole injection layers 31 and 32 is increased.
In some cases, the difference becomes 0 eV or more.

In FIG. 2, the solid line Ip of the anode (ITO) 20 is 5.0 eV, but the broken line 5.4 eV.
And is getting bigger. The present embodiment can be applied even with such a difference in Ip.

In FIG. 2, the anode (Ip = 5.0 eV)
In the case of (TO) 20, UV ozone surface treatment was performed at a high temperature of 150 ° C. On the other hand, in the case of the anode (ITO) 20 having Ip of 5.4 eV, after the UV ozone surface treatment, plasma surface treatment using a mixed gas of argon and oxygen was further performed.

In the latter case, it is considered that Ip was increased because the surface of the anode 20 was further cleaned.
Even in the latter case (Ip is 5.4 eV), it was possible to prevent the energy barrier between the anode 20 and the hole injection layers 31 and 32 from being large and causing a high voltage.

Furthermore, the value obtained by subtracting the Ip of the hole transport layer 40 from the Ip of the crystalline hole injection layer 31 and the Ip of the amorphous hole injection layer 32 from the hole transport layer 4
The values obtained by subtracting Ip of 0 are both +0.05 to −0.
It is preferably in the range of 4 eV.

Thus, a material having a difference in Ip between the hole injection layers 31 and 32 of +0.05 to −0.4 eV,
For example, it is preferable to use a material having a difference of −0.1 eV or −0.15 eV for the hole transport layer 40. In the example of FIG. 2 described above, the difference in Ip between the hole injection layers 31 and 32 and the hole transport layer 40 is −0.22 eV (= 5.17−).
5.40).

This is because the difference in Ip between the hole injection layers 31 and 32 is less than −0.4 eV, for example, the difference is −0.5.
This is because when a material such as eV is used for the hole transport layer 40, the energy barrier between the hole injection layers 31 and 32 and the hole transport layer 40 is large, which causes high voltage.

Here, the difference in Ip between the hole injection layers 31 and 32 and the hole transport layer 40 is −0.4 eV or more.
The negative range is wider than the difference of p (−0.2 eV) because the charge transfer between the hole injection layers 31 and 32 and the hole transport layer 40 is different between the inorganic material and the organic material. This is because the transfer of charges between organic materials is not the transfer of charges between them.

The difference in Ip between the crystalline hole injection layer 31 and the amorphous hole injection layer 32 is preferably ± 0.2 eV or less, more preferably ± 0.1 eV or less. In the example of FIG. 2, it is 0 eV. This is because if this difference is large, a higher voltage is brought about.

Further, in this embodiment, as the crystalline hole injection layer 31, in addition to copper phthalocyanine, aluminum phthalocyanine chloride, phthalocyanine, dilithium phthalocyanine, copper tetramethylphthalocyanine, chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium. Phthalocyanine oxide, magnesium phthalocyanine, copper octamethylphthalocyanine and the like can be used.

Further, as the amorphous hole injection layer 32, in addition to TBTA, N, N'-diphenyl-N,
N'-di (3-tert-butylphenyl) -4,4 '
-Diaminobiphenyl, 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane, 3-t
ert-Butoxy-4′-N, N-diphenylaminostilbenzene and the like can be used.

(Specific Examples 2 and 3) Further, in order to prevent the deterioration of the luminance life due to the weak adhesion of the amorphous hole injection layer 32, the film thickness of the cathode 80 made of Al,
5 and 6 show the results of an examination focusing on the film thickness of the amorphous hole injection layer 32 and the ratio of the film thicknesses of the two, as Concrete Example 2 and Concrete example 3 of the present embodiment, respectively.

(Specific Example 2) Same as that shown in FIG. 2 except that the thickness of the crystalline hole injection layer 31 made of copper phthalocyanine was 15 nm and the thickness of the cathode 80 made of Al was 150 nm. EL consisting of the element structure
Element S1 was produced.

Here, the film thickness of the cathode 80 made of Al is set to 1
The film thickness of the amorphous hole injection layer 32 made of TBTA was changed from 50 nm to 180 nm while keeping it constant at 50 nm. This element is 85 ℃, 500 cd / m ² ,
It was driven by 1/64 duty driving, but no non-light emitting portion was generated even after 1000 hours. That is, this specific example 2
However, the above-described effect of suppressing the generation of the non-light emitting portion was exhibited.

FIG. 5 shows that in the second specific example, the thickness of the cathode 80 made of Al is fixed to 150 nm and TBTA is used.
The thickness of the amorphous hole injection layer 32 is 50
It is a figure which shows the result of having investigated the brightness lifetime when changing from 180 nm to 180 nm.

Here, the brightness life is 500 at 85 ° C. above.
The luminance after 200 hours of cd / m ² and 1/64 duty driving is shown as a percentage compared with the initial luminance.
If it is 75% or more, there is no problem in practical use.

In FIG. 5, (a) shows the relationship between the film thickness of the amorphous hole injecting layer 32 (the TBTA layer film thickness is shown in the drawing) and the brightness life, and (b) shows the amorphous hole injecting layer 32. The relationship between the ratio B / A of the film thickness B of the injection layer 31 and the film thickness A of the Al cathode (TBTA layer film thickness / Al film thickness in the figure) and the luminance life is shown.

From FIG. 5A, the cathode 80 is Al,
If the film thickness is 150 nm and the film thickness of the amorphous hole injection layer 32 is 100 nm or more, 20
It can be seen that a luminance of 75% or more after 0 hour, that is, a practical luminance life can be secured and deterioration of the luminance life can be prevented.

Although the cause is not clear, the Al cathode 80
It is considered that the above stress and the stress amplified by heat are relaxed by the TBTA layer 32 which is made thick to some extent, and the peeling of the interface of the TBTA layer 32 is suppressed.

The stress from the Al cathode 80 is
It can be said without proof that the smaller the film thickness of, the smaller. Therefore, from the result of FIG. 5A, even if the film thickness of the cathode 80 is smaller than 150 nm, if the film thickness of the TBTA layer 32, that is, the amorphous hole injection layer 32 is 100 nm or more, it is practical. It can be said that the brightness life can be secured.

From the result shown in FIG. 5B, the film thickness B of the amorphous hole injection layer 32 and the film thickness A of the cathode 80 are obtained.
When the ratio B / A (TBTA layer film thickness / Al film thickness) is 0.6 or more, it can be said that a brightness of 75% or more after 200 hours can be secured and deterioration of the brightness life can be prevented.

Here, the upper limit of the ratio B / A can be 5.0. As described above, when the thickness of the amorphous hole injection layer 32 is thicker than 200 nm, the driving voltage becomes too high, which is not practical. Therefore, the thickness of the amorphous hole injection layer 32 is preferably 200 nm or less. caused by. Amorphous hole injection layer 3
When the upper limit of the film thickness of 2 is 200 nm, the film thickness of Al in consideration of the driving voltage is 40 nm or more, so the ratio B / A is determined to be 5.0 as the upper limit.

(Specific Example 3) The thickness of the crystalline hole injection layer 31 made of copper phthalocyanine was set to 15 nm, and TBTA was used.
The thickness of the amorphous hole injection layer 32 is 50
An organic EL element S1 having the same element structure as that shown in FIG. 2 was prepared except that the thickness was set to nm.

Here, the thickness of the amorphous hole injecting layer 32 made of TBTA is kept constant at 50 nm, and Al
The film thickness of the cathode 80 made of was changed from 40 nm to 200 nm. This device was placed at 85 ° C, 500 cd / m ² , 1
It was driven by / 64 duty driving, but no non-light emitting portion was generated even after 1000 hours. That is, also in the present Specific Example 3, the above-described effect of suppressing the generation of the non-light emitting portion was exhibited.

FIG. 6 shows the amorphous hole injection layer 32 made of TBTA having a thickness of 50 n in the third specific example.
The thickness of the cathode 80 made of Al is 40 n
It is a figure which shows the result of having investigated the brightness lifetime when changing from m to 200 nm. The brightness lifetime was the brightness after 200 hours, as in the above-described Concrete Example 2.

In FIG. 6, (a) shows the relationship between the film thickness of the cathode 80 (Al film thickness in the figure) and the luminance life, and (b) shows the film of the amorphous hole injection layer 31. The ratio B / A of the thickness B and the thickness A of the Al cathode (in the figure, TBT
The relationship between A layer thickness / Al film thickness (shown) and the luminance life is shown.

From FIG. 6A, the thickness of the amorphous hole injection layer 32 is 50 nm, and the Al cathode 80 is
If the film thickness is 80 nm or less, the brightness after 200 hours is 7
It can be seen that 5% or more, that is, a practical brightness life can be secured and deterioration of the brightness life can be prevented.

It is considered that this is also because the stress of the Al cathode 80 and the stress amplified by heat are alleviated by thinning the Al cathode 80, and the peeling of the interface of the TBTA layer 32 is suppressed.

The amorphous hole injection layer (TB
It is needless to say that the relaxation effect of the TA layer) 32 increases as the film thickness of the amorphous hole injection layer 32 increases. Therefore, from the result of FIG. 6A, the film thickness of the amorphous hole injection layer 32 is 50
Even if the thickness is smaller than nm, it can be said that a practical luminance life can be secured if the film thickness of the Al cathode 80 is 80 nm or less.

Further, in the result shown in FIG. 6B, the ratio B / A (TBTA) between the film thickness B of the amorphous hole injection layer 32 and the film thickness A of the cathode 80 is similar to that of FIG. 5B. When the layer thickness / Al film thickness) is 0.6 or more, a brightness of 75% or more after 200 hours can be secured, and deterioration of the brightness life can be prevented.

When the above organic EL device is mounted on an automobile and used, it is in a high temperature environment (for example, about 70 to 80 ° C.).
It is inevitable that Among the organic layers, the amorphous organic layer including the amorphous hole injecting layer is crystallized at a glass transition temperature (Tg) or higher to increase the unevenness of the film surface, which easily causes current leakage. Therefore, when it is to be mounted on a vehicle, it is preferable that the Tg of all the organic layers in the element is 120 ° C. or higher.

The organic EL element S1 of this embodiment is
For example, when it is used in a vehicle-mounted display or the like, the operating temperature is about -40 ° C to 120 ° C.

To improve the stability in a high temperature environment at such a use temperature, the adhesion of the CuPc film (crystalline hole injection layer) 31 which is a porphyrin compound,
In particular, it is necessary to improve the adhesiveness of the interface with the anode 20. It is considered that this is because the difference in linear expansion coefficient between the two is large.

Therefore, as the crystalline hole injection layer 31 in contact with the anode 20, it is preferable to provide a highly crystallized porphyrin compound layer with a small morphological change.

Specifically, in the value of the diffraction peak of copper phthalocyanine (CuPc), which is a porphyrin compound, which appears by the X-ray diffraction method, the amount of change in the diffraction peak due to heating within the operating temperature of the organic EL element is It is preferably within ± 25% of the diffraction peak.

The diffraction peak of CuPc is CuPc.
When the crystalline hole injection layer 31 made of CuPc, that is, the CuPc film 31 is measured by the X-ray diffraction method, the CuPc film 31 parallel to the substrate 10 (2
This is a diffraction peak of the (00) plane. Specifically, it corresponds to the peak occurring at 2θ = 6.68 ° shown in FIG. 7 and is hereinafter referred to as a CuPc crystallinity peak.

Then, in the present embodiment, at the value of this CuPc crystallinity peak (2θ = 6.68 °), that is, the integrated value of the peak, the operating temperature of the organic EL element S1 (for example, −
It is preferable that the amount of change in the CuPc crystallinity peak value due to heating within 40 ° C. to 120 ° C. is within ± 25% of the CuPc crystallinity peak before heating.

By suppressing the amount of change in the CuPc crystallinity peak value before and after heating within ± 25%, the adhesion of the CuPc film can be improved. Further, even when used in a high temperature environment, it is possible to reduce the change in the crystalline state of the organic material to the extent that a short circuit or a leak does not occur.

Incidentally, in the data shown in FIG.
Compared to the CuPc crystallinity peak value before heating, Cu after heating
The Pc crystallinity peak value is greatly changed to 1.5 times,
Shorts and leaks are more likely to occur.

C, in which the amount of change in the CuPc crystallinity peak value before and after heating was suppressed to within ± 25%.
The uPc film 31 can be realized, for example, by subjecting the surface of the anode 20, which is the base, to UV ozone treatment at 150 ° C., and then depositing CuPc at a material heating temperature of 520 ° C. to form a film.

In the present embodiment, such a CuPc film 31 improves the adhesiveness of the crystalline hole injection layer 31 and makes the organic EL element S suitable for a higher temperature environment.
1 can be provided.

In addition, as described above, it is important that the crystallinity of the crystalline hole injection layer 31 does not easily change in a high temperature environment after the device is formed. Therefore, the surface roughness of the anode 20 is important for forming a crystalline material directly above the anode (ITO) 20 into a stable film having high crystallinity. That is, a flatter film can form a stable film with higher crystallinity.

In this embodiment, the anode 20 is made of ITO. Specifically, its average surface roughness Ra is 2n.
It is desirable that it is m or less, and the 10-point average surface roughness Rz is 20 nm or less. For example, in the above example, the surface of ITO as the anode 20 formed on the glass substrate 10 can be polished so that Ra is about 1 nm or less and Rz is about 10 nm.

Further, the hole injection layer is composed of the crystalline hole injection layer on the anode side and the amorphous hole injection layer on the hole transport layer side, and the amorphous hole injection layer is thicker than the crystalline hole injection layer. If so, as the other organic layers, substrates, anodes, cathodes, etc., materials that have been used or may be used in organic EL devices can be appropriately adopted.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an organic EL element according to an embodiment of the present invention.

FIG. 2 is an energy band diagram of the organic EL element in the first embodiment.

FIG. 3 is a schematic cross-sectional view of an organic EL element as Comparative Example 1.

FIG. 4 is a schematic cross-sectional view of an organic EL element as Comparative Example 2.

FIG. 5: TBT with a constant thickness of the cathode made of Al
It is a figure which shows the result of having investigated the brightness lifetime when changing the film thickness of the amorphous hole injection layer which consists of A.

FIG. 6 is a diagram showing the results of examining the luminance life when the film thickness of an amorphous hole injection layer made of TBTA is kept constant and the film thickness of a cathode made of Al is changed.

FIG. 7 is a diagram showing X-ray diffraction spectra of a CuPc film before and after being left at a high temperature of 100 ° C. for 2 hours studied by the present inventors.

[Explanation of symbols]

20 ... Anode, 30 ... Hole injection layer, 31 ... Crystalline hole injection layer, 32 ... Amorphous hole injection layer, 40 ... Hole transport layer, 50 ... Light emitting layer, 60 ... Electron transport layer, 80 ...
cathode.

Claims (15)

[Claims] 1. On the anode (20), at least a hole injection layer (30), a hole transport layer (40) and a light emitting layer (5).
0), the electron transport layer (60), and the cathode (80) are sequentially laminated, wherein the hole injection layer is a crystalline hole injection layer (a crystalline organic compound located on the anode side). 31) and an amorphous hole injection layer (32) made of an amorphous organic compound located on the hole transport layer side, wherein the amorphous hole injection layer is thicker than the crystalline hole injection layer. Characteristic organic EL device. 2. The crystalline hole injection layer (31) has a film thickness of 20 nm or less, and the amorphous hole injection layer (32) has a film thickness of 50 nm or more. Organic EL device. 3. The amorphous hole injection layer (3)
The organic EL device according to claim 2, wherein the film thickness of 2) is 200 nm or less. 4. The value obtained by subtracting the ionization potential energy of the crystalline hole injection layer (31) from the ionization potential energy of the anode (20), and the ionization potential energy of the anode from the amorphous hole injection layer (32). The value obtained by subtracting the ionization potential energy of is −0.2 eV
It is above, The organic EL element of any one of Claim 1 thru | or 3 characterized by the above-mentioned. 5. A value obtained by subtracting the ionization potential energy of the crystalline hole injection layer (31) from the ionization potential energy of the anode (20) and the ionization potential energy of the anode, and the amorphous hole injection layer (32). The values obtained by subtracting the ionization potential energy of 2) are both 0 eV or more, and the organic EL element according to claim 4. 6. The hole transport layer (4) from the ionization potential energy of the crystalline hole injection layer (31).
The value obtained by subtracting the ionization potential energy of 0) and the value obtained by subtracting the ionization potential energy of the hole transport layer from the ionization potential energy of the amorphous hole injection layer (32) are
Both are in the range of +0.05 to -0.4 eV, The organic EL element of Claim 4 or 5 characterized by the above-mentioned. 7. The organic EL device according to claim 1, wherein the crystalline organic compound is a porphyrin compound. 8. The organic E according to claim 7, wherein the porphyrin-based compound is copper phthalocyanine.
L element. 9. The value of a diffraction peak of copper phthalocyanine, which is the porphyrin-based compound, which appears by an X-ray diffraction method, wherein the amount of change in the diffraction peak due to heating within the operating temperature of the organic EL device is the diffraction before the heating. The organic EL element according to claim 8, wherein the peak is within ± 25% of the peak. 10. The organic EL device according to claim 1, wherein the amorphous organic compound is an aromatic tertiary amine compound. 11. The cathode (80) is Al, and the ratio B / A of the film thickness B of the amorphous hole injection layer (32) to the film thickness A of the cathode is 0.6 or more. 11. The organic EL device according to claim 1, which is characterized in that. 12. The organic EL device according to claim 11, wherein the ratio B / A is 5.0 or less. 13. The cathode (80) is Al, the thickness thereof is 150 nm or less, and the thickness of the amorphous hole injection layer (32) is 100 nm or more. Item 13. The organic EL device according to any one of items 1 to 12. 14. The cathode (80) is Al, the thickness thereof is 80 nm or less, and the thickness of the amorphous hole injection layer (32) is 50 nm or more. Item 13. The organic EL device according to any one of items 1 to 12. 15. The anode (20) comprises an indium-tin oxide.
15. The organic EL device according to any one of items 1 to 14.