JP2003234194A - Organic el element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element having crystalline organic material which realizes a good luminous characteristics by preventing short-circuit and leak of electric current in service temperature. <P>SOLUTION: The organic EL element S1 is formed by laminating crystalline CuPc film 30 as a hole-injection layer, a hole transport layer 40 made of an amorphous organic material, an emitter layer 50, an electron transport layer 60, and an electron injection layer 70, between a pair of electrodes 20 and 80. With respect to value of the diffraction peak which appears by an X-ray diffraction method of the CuPc film 30, the variation of the diffraction peak value by heating in the service temperature of the organic EL element has become less than 25% of the diffraction peak value before heating. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL (electroluminescence) element having an organic material as a light emitting material and a method for manufacturing the same, and is particularly suitable for application to an in-vehicle display exposed to a high temperature environment. .

[0002]

2. Description of the Related Art An organic EL element is self-luminous, has excellent visibility, and can be driven at a low voltage of several V to several tens of V. Therefore, it is possible to reduce the weight including a drive circuit. Therefore, it can be expected to be used as a thin film display, lighting, and backlight. Another feature of the organic EL element is that it has a wide variety of colors.

The basic structure of an organic EL device is that a plurality of organic thin film laminates are formed on electrodes formed on a substrate, and then electrodes are formed on the organic thin film laminates. As a material used for the organic thin film, there are mainly a low molecular weight type using a vacuum deposition method and a high molecular weight type applying a liquid to a substrate.

Materials used mainly in low molecular weight systems show an amorphous property without crystallinity when formed into a film by a vacuum vapor deposition method. In other words, it is a material in which no diffraction peak appears even when it is analyzed by the X-ray diffraction method.

However, an amorphous organic thin film is crystallized when it exceeds a glass transition point (hereinafter referred to as Tg point) due to a temperature change, and unevenness is generated in the film to shorten the distance between electrodes, resulting in short circuit of current or short circuit. Problems such as leakage and electric field concentration due to the unevenness occur.

In view of this, a technique for extending the life of such a low molecular weight organic thin film material by forming a crystal structure is disclosed in Japanese Patent Application Laid-Open No. 1733095/1993 and Japanese Patent Application Laid-Open No. 5730/95.
No. 182764 (Patent Document 1,
2).

The former publication is characterized in that the hole transport layer and the light emitting layer are made of an organic compound thin film having a crystal structure. In the embodiment, N, N'-diphenyl-N, N is formed in the hole transport layer. '
-Di (3-methylphenyl) -1,1'biphenyl-
4,4′-diamine (hereinafter referred to as “TPD”) and an aluminum complex of 8-hydroxyquinoline (hereinafter referred to as “Al”) in the light emitting layer.
It is described that a crystalline organic thin film was formed by using () (q) and setting the substrate temperature during film formation to 50 ° C.

Further, in the latter publication, the same materials as those described above, that is, TPD and Alq, are used for the hole transport layer and the light emitting layer, after forming the hole transport layer, the light emitting layer is formed, and immediately thereafter. It is described that heat treatment is performed or heat treatment is performed after forming all layers to make Alq, which is a light emitting layer, into a microcrystalline aggregate structure.

[0009]

[Patent Document 1] Japanese Unexamined Patent Publication No. 3-173095

[0010]

[Patent Document 2] Japanese Unexamined Patent Publication No. 5-182664

[0011]

However, the inventors of the present invention have found that a single film of TPD and Alq formed on a glass substrate with an ITO (transparent electrode) under the conditions described in each of the above-mentioned prior arts is X-rayed. The crystalline state was analyzed by the diffraction method, but no diffraction peak showing crystallinity appeared. That is, in each of the above-mentioned prior art publications, although the organic thin film was said to be crystalline, it was such that the diffraction peak by the X-ray diffraction method did not appear.

The present inventors presume the result as follows. An image diagram is shown in FIG. (A) is a structure showing an amorphous state, and (b) is considered to be a crystal structure referred to in each of the above-mentioned prior art publications.

That is, since the diffraction peak does not appear in the X-ray diffraction method, the crystal structure described in the above-mentioned conventional publication is
It is generally considered that it is not a crystal with a structure in which molecules are regularly arranged parallel to the substrate, but a structure in which microcrystals are aggregated or a structure in which microcrystals are scattered in an amorphous thin film. .

According to the studies by the present inventors, in each of the above-mentioned prior art publications, although the film structure of the organic compound is preliminarily formed as a thin film having a microcrystalline agglomerated structure so as not to be easily changed by heat, microcrystals are used. By adopting an agglomerated structure, the contact area at each layer interface is reduced and the light emission efficiency is reduced due to the decrease in charge mobility, resulting in a decrease in brightness and uneven brightness, and a short circuit between the upper and lower electrodes due to an increase in surface irregularities, etc. There is a new problem that leaks occur.

Here, the decrease in brightness has a temperature dependency, and the higher the operating temperature is, the faster the brightness is. Further, the brightness unevenness is caused by uneven brightness in the element, resulting in a bright area and a dark area. It is to end up.

The present invention has been made in view of the above-mentioned novel problems found by the present inventors, and is an organic material having a crystallinity including microcrystals, rather than an amorphous property in which a film is likely to change. It is an object of the present invention to prevent short-circuiting and leakage of current within an operating temperature and realize good luminance characteristics in an organic EL device having

[0017]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have made earnest studies. As a result, even if the organic thin film does not have a glass transition temperature and is made of an organic material having a crystallinity such that a diffraction peak appears in the X-ray diffraction method, the above-mentioned decrease in brightness or uneven brightness, short-circuit or leak may occur. Was found to occur.

That is, the cause of the above-mentioned decrease in brightness, uneven brightness, short-circuit and leak is due to the change of the crystal state of the material showing crystallinity such as copper phthalocyanine (CuPc) which is often used in the hole injection layer. Found.
The cause of this occurrence will be specifically described based on the data of the experiment conducted by the present inventors.

After forming an anode ITO (transparent electrode) on a glass substrate and subjecting it to a surface treatment with plasma of a mixture of argon and oxygen, CuPc was formed as a hole injection layer at a material heating temperature of 420 ° C. and a film thickness of 10 nm. After film formation, triphenylamine tetramer is formed in the hole transport layer, Alq to which dimethylquinacridone is added as the light emitting layer, Alq in the electron transport layer, LiF in the electron injection layer, and Al in the cathode, and then sealed. An organic EL device sealed with a can was made as a prototype. Hereinafter, this prototype device is referred to as a prototype. Here, of the above organic thin films, CuP
c is crystalline, and the other layers are amorphous.

FIG. 8 shows the voltage-luminance characteristic (VI characteristic) when this prototype was left at a high temperature for 12 hours at 100.degree. As shown in FIG. 8, it was found that the VI characteristic was shifted to the plus side by about 3 V after the high temperature standing as compared with the initial stage before the high temperature standing.

This increases the load on the drive circuit, leading to an increase in cost in circuit design. Also,
Since it occurs partially in the same element, a region where current easily flows and a region where current does not flow are formed, and as a result, it is recognized as uneven brightness.

The material having the lowest Tg point among the layers in the above prototype, that is, the organic thin film, is triphenylamine 4
It is a monomer and is about 144 ° C. Since the storage at 100 ° C. is stored in an environment lower than the Tg point of the triphenylamine tetramer by 40 ° C. or more, the C
It is considered that the influence of the progress of the microcrystalline aggregate structure of the amorphous film other than uPc is small.

Therefore, C, which is an organic material having crystallinity, is used.
Attention was paid to the change in the crystalline state of the uPc film (hole injection layer). As a result, they have found that the crystalline state of this CuPc film is 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 of the crystal state, the leaving environment temperature was increased to 120 ° C. for acceleration, and the leaving time was evaluated at 2 hours. Hereinafter, standing under this condition is referred to as accelerated high temperature standing.

CuPc was deposited on a glass substrate with ITO under the same conditions as in the prototype in which the VI characteristic was shifted by about 3 V as described above. C in this case
FIG. 9 shows the results of analyzing the crystalline state of the uPc film by X-ray diffraction before and after the accelerated high temperature standing.

As shown in FIG. 9, in the diffraction peak,
The peak occurring at 2θ = 6.68 ° is derived from the crystal structure of CuPc. In FIG. 9, the solid line shows the peak before the accelerated high temperature standing, that is, the initial peak, and the broken line shows 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. That is, the peak value (integral value) of the accelerated high temperature of 120 ° C. for 2 hours is 1.
It has changed five times.

From the above, the inventors of the present invention, in the above prototype, after forming the hole transport layer, the light emitting layer, the electron transport layer, the cathode, etc. on the CuPc film which is the hole injection layer, that is, The CuPc film undergoes such a change in crystalline state after it becomes a light emitting device, which is caused by V-
It is considered that this is a major cause of the I characteristic change, which causes a decrease in brightness, uneven brightness, and a short circuit or a leak.

In addition to the low molecular weight material, such a phenomenon similarly occurs in the case of a material having a diffraction peak in X-ray diffraction such as a PPV (polyphenylvinylene) material in a high molecular weight material. It is thought that.

Therefore, the inventors of the present invention, in an organic EL element containing an organic material having crystallinity, as a countermeasure against the change in the crystalline state of the organic material under a high temperature environment, It was thought that it is important to form a film so that the crystallinity is as high as possible during the film formation, and the present invention was created.

That is, according to the first aspect of the invention, the organic EL element includes at least one organic material exhibiting crystallinity, and the value of the diffraction peak of the organic material exhibiting crystallinity which appears by the X-ray diffraction method. The amount of change in the diffraction peak value due to heating within the operating temperature of the organic EL element is within ± 25% of the diffraction peak value before heating. Here, the crystallinity includes microcrystals.

As in the present invention, the amount of change in the diffraction peak value due to heating within the operating temperature of the organic EL element in the value of the diffraction peak appearing by the X-ray diffraction method of the organic material exhibiting crystallinity is determined by the diffraction before heating. If it is reduced to within ± 25% of the peak value, even if it is used in a high temperature environment, the change in the crystalline state of the organic material should be small to the extent that there is no decrease in brightness, brightness unevenness, and even short circuit or leakage. You can

Therefore, according to the present invention, in an organic EL element containing an organic material having crystallinity, it is possible to prevent a short circuit and a leak of a current within a working temperature and realize a good luminance characteristic.

Here, as in the invention described in claim 2,
When the ITO film made of indium-tin oxide is formed on the substrate, the organic material exhibiting crystallinity is IT
It can be configured as an organic film formed on the O film.

Further, as in the invention described in claim 3,
The organic material exhibiting crystalline characteristics can be a copper phthalocyanine film, and in this case, the diffraction peak value is the diffraction peak value of the (200) plane parallel to the substrate in the copper phthalocyanine film.

In the invention according to claim 6, an ITO film made of an indium-tin oxide is formed on the substrate,
A method for manufacturing an organic EL element, which comprises forming an organic material exhibiting crystallinity on an ITO film, wherein bound water on the surface of the ITO film is desorbed before forming the organic material. Is characterized by.

According to this, it is possible to reduce bound water as well as adsorbed water on the surface of the ITO film which is a base of the crystalline organic material. Therefore, the crystallinity of the organic material formed on the ITO film in which the bound water is reduced can be increased. Therefore, 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 there is no reduction in luminance, luminance unevenness, short-circuiting or leakage.

Therefore, according to the present invention, in an organic EL element containing an organic material having crystallinity, it is possible to prevent a short circuit and a leak of a current within a working temperature and realize a good luminance characteristic.

Here, as in the invention described in claim 7,
In the spectrum due to water measured by the temperature programmed desorption method on the surface of the ITO film after the desorption treatment, the peak value of bound water around 330 ° C. was the same as the peak value of bound water on the surface of the ITO film before the desorption treatment. It is preferable to perform the desorption treatment so as to be within 50% by comparison.

Further, as in the invention described in claim 8, in the spectrum due to water measured by the temperature programmed desorption method on the surface of the ITO film after the desorption treatment, 330
It is more preferable to perform the desorption treatment so that the bound water peak around 0 ° C disappears.

The invention described in claim 4 can be manufactured by the manufacturing method according to claim 8, and is an IT made of an indium-tin oxide on a substrate.
What is claimed is: 1. An organic EL element comprising an O film and an organic material exhibiting crystallinity formed on an ITO film, wherein the ITO film has a moisture-induced It is characterized by the absence of a bound water peak around 330 ° C. in the spectrum.

According to this, similarly to the invention of claim 8, in an organic EL element having an organic material having crystallinity,
It is possible to prevent short-circuiting and leakage of current within the operating temperature and realize good luminance characteristics.

Here, in the invention described in claim 2 and claim 4, as in the invention described in claim 5,
An organic material having crystallinity may be formed directly on the ITO film. That is, the ITO film and the film of the organic material exhibiting crystallinity can be in direct contact with each other.

Further, in the invention according to claim 9, an ITO film made of an oxide of indium-tin is formed on the substrate,
A method of manufacturing an organic EL element, comprising depositing an organic material exhibiting crystalline characteristics on an ITO film, wherein the ITO film is heat-treated at a temperature of 250 ° C. or higher before depositing the organic material. It is characterized by

According to this, the bound water can be reduced together with the adsorbed water on the surface of the ITO film which is the base of the crystalline organic material. Therefore, the bound water is reduced as in the case of the above-mentioned invention. The organic material formed on the ITO film can have high crystallinity.

Therefore, according to the present invention, in an organic EL element containing an organic material having crystallinity, it is possible to prevent a short circuit and a leak of a current within a working temperature and realize a good luminance characteristic.

According to the tenth aspect of the invention, an ITO film formed of an indium-tin oxide is formed on the substrate, and an organic material exhibiting crystallinity is formed on the ITO film. A method of manufacturing an EL element, comprising forming a film of an organic material exhibiting crystallinity on an ITO film, and then performing heat treatment in a vacuum or an inert gas atmosphere to form the organic material exhibiting crystallinity. Characterized by completing the membrane.

According to this, the crystallinity of the crystalline organic material film formed on the ITO film can be enhanced by the heat treatment. For example, the above claim 1
The crystallinity is increased to such a small level that the amount of change in the diffraction peak value as described in the invention is within ± 25% of the diffraction peak value before heating.

Therefore, even when used in a high temperature environment, it is possible to reduce the change in the crystalline state of the organic material to such an extent that there is no reduction in brightness, uneven brightness, short-circuiting or leakage. Therefore, according to the present invention as well, in the organic EL element including the organic material having crystallinity, it is possible to prevent the short circuit and the leakage of the current within the operating temperature and realize the excellent luminance characteristic.

According to the study of the present inventors, if the temperature of the heat treatment is 70 ° C. or higher, the effect of the invention of claim 10 can be obtained more reliably in the organic EL element used in a high temperature environment. It is preferable because it can be exhibited.

In each of the above manufacturing methods, ITO is also used.
An organic material having crystallinity can be formed directly on the film. That is, the ITO film and the film of the organic material exhibiting crystallinity can be directly contacted with each other.

The reference numerals in parentheses of the above means are examples showing the correspondence with the concrete means described in the embodiments described later.

[0053]

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 structure of an organic EL element S1 according to an embodiment of the present invention.

An anode 20 made of indium-tin oxide (hereinafter referred to as ITO) is formed on a substrate 10 made of transparent glass. A hole injection layer 30 made of CuPc (copper phthalocyanine) as an organic material having crystallinity is formed on the anode 20.
A hole transport layer 40 made of a triphenylamine tetramer is formed on the surface of 0.

On the hole transport layer 40, a light emitting layer 50 made of Alq added with dimethylquinacridone is formed, and on the light emitting layer 50, an electron transport layer made of Alq (aluminum complex of 8-hydroxyquinoline). The layer 60 is formed. Further, on the electron transport layer 60, Li
An electron injection layer 70 made of F is formed, and A is formed on the electron injection layer 70.
A cathode 80 made of 1 is formed.

Thus, the hole injection layer 30 made of an organic material having crystallinity is provided between the pair of electrodes 20, 80.
And a layer made of an organic material having an amorphous property, such as the hole transport layer 40, the light emitting layer 50, the electron transport layer 60, and the electron injection layer 70, are stacked to form the organic EL element S1.

In this organic EL element S1, the anode 2
By applying an electric field between the anode 0 and the cathode 80, holes are injected from the anode 20 and electrons are injected and transported from the cathode 80 to the light emitting layer 50, respectively, and the electrons and holes are recombined in the light emitting layer 50. However, the light emitting layer 50 emits light by the energy at that time. Then, the emitted light is, for example, taken out from the substrate 10 side and visually recognized.

By the way, the organic EL element S1 of the present embodiment
Is employed in, for example, a vehicle-mounted display, and its operating temperature is about -40 ° C to 120 ° C.

CuP which is an organic material exhibiting crystallinity
the hole injection layer 30 made of c, that is, the CuPc film 30
CuP parallel to the substrate 10 when measured by the line diffraction method
The diffraction peak of the (200) plane of the c film 30 is the CuPc film 2
It is a diffraction peak showing crystallinity of 0. This diffraction peak corresponds to the peak occurring at 2θ = 6.68 ° shown in FIG. 9 and is hereinafter referred to as a CuPc crystallinity peak.

In this 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, −
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 to be within ± 25%, there is no reduction in brightness, uneven brightness, short-circuiting or leakage even when used in a high temperature environment. In addition, the change in the crystalline state of the organic material can be reduced.

Therefore, according to the organic EL element S1 of the present embodiment, it is possible to prevent short-circuiting and leakage of current within the operating temperature and realize good luminance characteristics.

By the way, as described above, in the organic EL element having the conventional organic material having crystallinity, the organic EL element shown in FIG.
As shown in, the CuPc crystallinity peak value after heating was significantly changed to 1.5 times as compared with the CuPc crystallinity peak value before heating, and a short circuit and a leak occurred,
As shown in FIG. 8, the VI characteristic is largely shifted to cause a decrease in brightness and uneven brightness.

Next, a method for manufacturing the organic EL element S1 of this embodiment will be described with reference to a concrete example, although not limited thereto.

[First Manufacturing Method] The ITO film 20 as an anode is formed on the glass substrate 10 by sputtering or the like, and the surface of the ITO film 20 is irradiated with ultraviolet rays while being heated to 300.degree. Hereinafter, the process for the ITO film 20 is performed
This is called V-300 ° C. treatment.

After this UV-300 ° C. treatment, a CuPc film 30 as a hole injection layer is formed by vapor deposition at a material heating temperature of 420 ° C. to a film thickness of 10 nm. afterwards,
A hole transport layer 40 comprising a triphenylamine tetramer film,
A light emitting layer 50 made of Alq (host material) + dimethylquinacridone (guest material), an electron transport layer 60 made of Alq, an electron injection layer 70 made of LiF, and a cathode 80 made of Al are sequentially formed. Thus, the organic E shown in FIG.
The L element S1 is completed.

Here, with respect to the ITO film 20 subjected to the UV-300 ° C. treatment and the CuPc film 30 formed thereon, X-rays were taken before and after the above accelerated high temperature exposure (120 ° C., 2 hr). Diffraction analysis was performed.

As a result, it was confirmed that the CuPc crystallinity peak occurring at 2θ = 6.68 ° had a very small ratio of 1.02 after the standing treatment to the value before the standing treatment. It was In other words, CuPc at the time of film formation of this manufacturing method
The crystallinity of film 30 is shown to be very high and stable.

Further, the completed organic E of this embodiment
The sealing element obtained by sealing the L element S1 with a sealing can is
As a result of confirmation under the above-mentioned accelerated high temperature storage condition of 2 hr, V-
Almost no shift of the I characteristic was observed, and no decrease in brightness or uneven brightness was observed. In addition, no short circuit or leakage of current occurred.

That is, the organic EL element S1 manufactured by the first manufacturing method of this embodiment can prevent short circuit and leakage of current within the operating temperature and can realize good luminance characteristics.

Such an effect is due to the UV-300 ° C. treatment in the above manufacturing method, and the mechanism for realizing the effect by the treatment will be described in more detail.

It has been known for a long time that the cleaning treatment of the ITO film surface is important in order to efficiently inject holes from the ITO film 20 as the anode into the CuPc film 30 as the hole injection layer. . However, in general, IT after cleaning
It is evaluated by the ionization potential (Ip) of the surface of the O film, and the present inventors have considered that the Ip of the ITO film 20 is 5.5 eV immediately after the cleaning treatment of the ITO film 20 in view of the hole injection characteristics and the like.
It was judged that there was no problem if the following.

However, according to the study by the present inventors, Ip is 5.45 eV when the plasma cleaning treatment of argon and oxygen (ratio 1: 1) is performed for 5 minutes, and Ip when only the UV treatment is performed for 20 minutes. Was 5.5 ev, and the Ip when the above UV-300 ° C. treatment was performed for 20 minutes was 5.46 ev, which was not a big difference.

Nevertheless, only the element which had been subjected to the UV-300 ° C. treatment did not cause the VI characteristic shift after being left at a high temperature, that is, the decrease in brightness and the uneven brightness, and the short circuit and the leak did not occur. That is, it is shown that the crystallinity of the crystalline organic material formed on ITO is not determined only by Ip but also exists in other factors.

Therefore, in the UV-300 ° C. treatment, since the heat treatment is involved, attention is paid to the water content on the ITO surface, and the thermal desorption method (thermal desorption) is used.
The amount of water generated at each temperature, that is, the amount of water desorbed from the surface of the ITO film 20 was measured by an n method (hereinafter referred to as TDS method).

In FIG. 2, the ITO film 2 is formed on the glass substrate 10.
It is the measurement result by the TDS method immediately after forming 0. This TDS spectrum has a molecular weight, that is, M
The spectrum of H ₂ O in which / z is 18 or OH in which z is 17 is measured.

From the results shown in FIG. 2, it can be seen that there are peaks of water desorption at 70 ° C. and 330 ° C. The former is water that is present as adsorbed water that is physically adsorbed on the surface of the ITO film 20, and the latter is water that is present as bound water that is chemically bonded to ITO on the surface of the ITO film 20. it is conceivable that. Therefore, the bound water on the surface of the ITO film 20 is C
It is considered to be one of the factors that determine the crystallinity during the formation of the uPc film 30.

Actually, the ITO film 2 is formed on the glass substrate 10.
FIG. 3 shows the TDS spectrum when the film of 0 was heat-treated at a temperature of 300 ° C. in a nitrogen atmosphere.
When this heat treatment is not performed, that is, T shown in FIG.
Compared to the DS spectrum, the peak value at 330 ° C is 50
% Has been reduced. Further, FIG. 4 shows a TDS spectrum when the heat treatment at 300 ° C. is performed in vacuum. In this case, the peak at 330 ° C. is hardly recognized.

30 in these nitrogen atmospheres or in vacuum
The organic EL element S1 created by heat treatment at 0 ° C.
As a result of confirming the sealing element sealed with a sealing can under the above-described accelerated high temperature storage condition of 120 ° C. and 2 hours, there was almost no shift in VI characteristics, and no decrease in brightness or uneven brightness was observed. In addition, no short circuit or leakage of current occurred.

From the above, the ITO film 2 is formed on the substrate 10.
In the method of manufacturing an organic EL element in which 0 is formed and an organic material having crystallinity such as the CuPc film 30 is formed on the ITO film 20, ITO is formed before forming the organic material.
It is effective to remove the bound water on the surface of the membrane 20.

As a result, the adsorbed water and the bound water can be reduced on the surface of the ITO film 20 which is the base of the organic material having crystallinity, so that the formed organic material has high crystallinity. Therefore, it is possible to prevent short circuit and leakage of current within the operating temperature and realize good luminance characteristics.

Here, as shown in FIG. 3, in the TDS spectrum due to water on the surface of the ITO film 20 after the desorption process, the peak value of bound water around 330 ° C.
The peak value of bound water on the surface of the ITO film 20 before the desorption treatment is preferably within 50% of the peak value.

Furthermore, as shown in FIG. 4, TDS due to water on the surface of the ITO film 20 after the desorption process.
It is even more preferable to eliminate the bound water peak around 330 ° C. in the spectrum.

In order to reduce the bound water existing on the surface of the ITO film 20 to within about 50%, the CuPc film 3 is used.
Before forming a crystalline organic material such as 0 on the ITO film 20, the heat treatment temperature of the ITO film 20 is preferably set to 250 ° C. or higher.

Further, according to the present embodiment, the ITO film 20 made of indium-tin oxide is formed on the substrate 10, and the organic material exhibiting crystallinity such as the CuPc film 30 is replaced with IT.
An organic EL device formed on an O film 20 comprising:
There is provided the organic EL element S1 characterized in that the TO film 20 does not have a bound water peak at around 330 ° C. in the water-induced spectrum measured on the surface thereof by the TDS method.

According to this, it is possible to prevent short circuit and leakage of current within the operating temperature and realize good luminance characteristics.

[Second Manufacturing Method] In the first manufacturing method of this embodiment described above, Cu, which is an organic material exhibiting crystallinity, is used.
The crystallinity of the CuPc film 30 is increased by heat-treating the ITO film 20 that is the base of the Pc film 30 and the like.

In the second manufacturing method of this embodiment, CuP
The focus is on the material temperature when the c-film 30 is formed. An ITO film 20 as an anode is formed on the glass substrate 10 by sputtering or the like. In this glass substrate with an ITO film, the above-mentioned plasma cleaning treatment of argon and oxygen was performed, and CuP as a hole injection layer was formed on the ITO film 20.
The c film 30 is formed at a material heating temperature of 420 ° C. by an evaporation method. This will be referred to as a 420 ° C. film-formed product.

On the other hand, in the glass substrate with the ITO film,
The plasma cleaning process using argon and oxygen described above is performed to
On the TO film 20, a CuPc film 30 as a hole injection layer
Is formed at a material heating temperature of 520 ° C. by an evaporation method. This will be referred to as a 520 ° C. film-formed product.

Thereafter, in each of the 420 ° C. film-formed product and the 520 ° C. film-formed product, the hole transport layer 40, the light emitting layer 50, the electron transport layer 60, on the CuPc film 30 as in the first manufacturing method. The electron injection layer 70 and the cathode 80 are sequentially formed to manufacture the organic EL element S1.

Here, with respect to each of the 420 ° C. film-formed product and the 520 ° C. film-formed product, the above accelerated high temperature storage (120
C by X-ray diffraction analysis before and after the treatment at 2 ° C. for 2 hours.
The ratio of the uPc crystal peak values was investigated. Further, the shift of the VI characteristics before and after the above-mentioned accelerated high temperature standing after sealing with a sealing can was examined.

In the case of the 420 ° C. film-formed product, the ratio of the CuPc crystallinity peak is about 1.5 (see FIG. 9 above) and the shift amount is about 3
On the other hand, in the case of the 520 ° C. film-formed product, the ratio of the CuPc crystallinity peak was about 1.15, and the shift amount was about 1 V, which was favorable.

Further, another example of the second manufacturing method will be described.
An ITO film 20 as an anode is formed on the glass substrate 10 by sputtering or the like. The surface of the ITO film 20 on the glass substrate with the ITO film is irradiated with ultraviolet rays while being heated to 150 ° C. (UV-150 ° C. treatment).

Then, a CuPc film 30 as a hole injection layer is formed on the ITO film 20 by a vapor deposition method at a material heating temperature of 5
The film is formed at 20 ° C. Then, the hole transport layer 40 and the light emitting layer 5 are formed on the CuPc film 30 as in the first manufacturing method.
0, the electron transport layer 60, the electron injection layer 70, and the cathode 80 are sequentially formed to manufacture the organic EL element S1.

The organic EL device S1 thus obtained
As a result of confirming the sealed element in which the above was sealed with a sealing can under the above-described accelerated high temperature storage condition of 120 ° C. and 2 hr, the VI characteristic shift was small, and no decrease in brightness or uneven brightness was observed.
In addition, no short circuit or leakage of current occurred. By the way, the shift amount of the VI characteristic before and after the accelerated high temperature standing was 1.2 V, and the ratio of the CuPc crystallinity peak was 1.
It was 21.

In another example, the surface of the ITO film 20 on the glass substrate with the ITO film formed in the same manner as above is irradiated with ultraviolet rays at room temperature (UV-normal temperature treatment). Then, CuPc as a hole injection layer is formed on the ITO film 20.
The film 30 is formed at a material heating temperature of 520 ° C. by a vapor deposition method.

Thereafter, similarly to the above, the sealing element in which the organic EL element S1 obtained by sequentially depositing the upper layers 40 to 80 was hermetically sealed with a sealing can was confirmed under the conditions of 120 ° C. and 2 hours of the above accelerated high temperature standing. .

As a result, the VI characteristic shift is small,
No decrease in brightness or uneven brightness was observed. In addition, no short circuit or leakage of current occurred. In this example, the shift amount of the VI characteristic before and after the accelerated high temperature standing was 1.5 V, and the ratio of the CuPc crystallinity peak was 1.21.

As described above, the film formation temperature of the CuPc film 30 is set to 5
According to the second manufacturing method in which the temperature is 20 ° C., regardless of the surface treatment method of the ITO film 20, the organic material satisfying the required characteristics can be obtained without performing the UV-300 ° C. treatment adopted in the first manufacturing method. An EL device can be obtained. This indicates that the factors that influence the crystallinity of CuPc exist not only in the ITO surface but also in the film forming method.

That is, the crystallinity of the CuPc film 30 is very high and stable even by the second manufacturing method of the present embodiment, and the organic EL element S1 manufactured by the CuPc film 30 has a short circuit of current within the operating temperature and a short circuit. Leakage can be prevented and good luminance characteristics can be realized.

[Third Manufacturing Method] In the third manufacturing method of this embodiment, CuPc, which is a film of an organic material exhibiting crystallinity, is used.
After the film 30 is formed on the ITO film 20, heat treatment is performed in a vacuum or an inert gas atmosphere to form CuP.
The film formation of the c film 30 is completed.

That is, the ITO film 2 is formed on the glass substrate 10.
0 is formed, a CuPc film 30 is formed thereon by a vapor deposition method, etc., and the CuPc film 30 is heat-treated, and then the hole transport layer 40, the light emitting layer 50, the electron transport layer 60, the electron injection layer are formed thereon. 70 and a cathode 80 are sequentially formed to form an organic EL element S1.
To manufacture. A specific example of the third manufacturing method performed by the present inventors will be described.

(Specific Example 1 of Third Manufacturing Method) An ITO film 20 as an anode is formed on a glass substrate 10 by sputtering or the like. I in the glass substrate with the ITO film
The surface of the TO film 20 was subjected to the plasma cleaning treatment of argon and oxygen described above.

Then, a CuPc film 30 as a hole injection layer is formed on the ITO film 20 by a vapor deposition method at a material heating temperature of 4
It was formed at a temperature of 20 ° C. and a film thickness of 10 nm. Subsequently, heat treatment was performed in vacuum at a substrate temperature of 150 ° C. for 20 minutes.

Thereafter, the hole transport layer 40 made of a triphenylamine tetramer film, the light emitting layer 50 made of Alq (host material) + dimethylquinacridone (guest material), and Al.
An electron transport layer 60 made of q, an electron injection layer 70 made of LiF, and a cathode 80 made of Al are sequentially formed.

Organic EL element S1 thus obtained
As a result of confirming the sealing element in which the above was sealed with a sealing can under the above accelerated high temperature storage condition of 120 ° C. for 2 hours, the VI characteristic shift was small, and no decrease in brightness or uneven brightness was observed.
In addition, no short circuit or leakage of current occurred. By the way, the shift amount of the VI characteristic before and after the accelerated high temperature standing was 1.0 V, and the ratio of the CuPc crystallinity peak was 1.
It was 13.

(Specific example 2 of the third manufacturing method) Similar to the specific example 1, the ITO film 20 is formed on the glass substrate 10 and plasma-cleaned with argon and oxygen, and then C
The uPc film 30 was formed by vapor deposition at a material heating temperature of 420 ° C. and a film thickness of 10 nm. Then, in this example, heat treatment was performed for 20 minutes at a substrate temperature of 100 ° C. in a vacuum.

Thereafter, similarly to the above, the sealing element in which the organic EL element S1 obtained by sequentially depositing the upper layers 40 to 80 was sealed with a sealing can was confirmed under the conditions of 120 ° C. and 2 hours for the accelerated high temperature standing. .

As a result, the shift of the VI characteristic is small,
No decrease in brightness or uneven brightness was observed. In addition, no short circuit or leakage of current occurred. In this example, the shift amount of the VI characteristic before and after the accelerated high temperature standing was 1.0 V, and the ratio of the CuPc crystallinity peak was 1.15.

(Specific Example 3 of Third Manufacturing Method) As in Specific Example 1, the ITO film 20 is formed on the glass substrate 10 and subjected to plasma cleaning treatment with argon and oxygen, and then C
The uPc film 30 was formed by vapor deposition at a material heating temperature of 420 ° C. and a film thickness of 10 nm. Then, in this example, heat treatment was performed at a substrate temperature of 70 ° C. for 20 minutes in a vacuum.

Thereafter, similarly to the above, the sealing element in which the organic EL element S1 obtained by sequentially depositing the upper layers 40 to 80 was sealed in a sealing can was confirmed under the conditions of 120 ° C. and 2 hours of the above accelerated high temperature standing. .

As a result, the shift of the VI characteristic is small,
No decrease in brightness or uneven brightness was observed. In addition, no short circuit or leakage of current occurred. In this example, the shift amount of the VI characteristic before and after the accelerated high temperature standing was 1.6 V, and the ratio of the CuPc crystallinity peak was 1.25.

As described above, according to the third manufacturing method, the CuPc film 30, which is a film of an organic material exhibiting crystallinity, is ITO.
After the film is formed on the film 20, the crystallinity of the formed CuPc film 30 can be enhanced by performing the heat treatment in a vacuum or an inert gas atmosphere.

It is considered that this is because the molecules in the CuPc film 30 vibrate due to the activation energy by heat, and the solid state shifts to a more stable phase. This has a strong correlation with temperature. According to the study by the present inventors, it has been confirmed that the crystal peak of the CuPc film 30 by the X-ray diffraction becomes larger and the crystallinity is improved before the heat treatment is actually performed.

From the specific examples 1 to 3, the temperature at which the CuPc film 30 is heat-treated in the third manufacturing method is 7
If the temperature is 0 ° C. or higher, the crystallinity of the CuPc film 30 is sufficiently increased, and even if the CuPc film 30 is used in a high-temperature environment, the brightness is not lowered, the brightness is uneven, and a short circuit or a leak does not occur.
The change in the crystalline state of the uPc film 30 can be reduced.

As described above, also by the third manufacturing method, in the organic EL element containing the organic material having crystallinity, it is possible to prevent short circuit and leakage of current within the operating temperature and realize good luminance characteristics. It should be noted that since the film to be heated is re-separated by the heat treatment, the upper limit of the heat treatment temperature is, of course, equal to or lower than the evaporation temperature or the sublimation temperature of the film to be heated. .

Here, the above accelerated high temperature storage (120 ° C., 2
The ratio of CuPc crystalline peaks before and after hr) and VI
The relationship with the characteristic shift amount will be summarized. The same relationship is shown as a graph in FIG. 5, and the data that is the basis of FIG.
Shown in. In FIGS. 5 and 6, the CuPc crystallinity peak value ratio is described as “X-ray diffraction peak ratio”, and the VI characteristic shift amount is described as “VI shift”.

As described above, the ratio of the CuPc crystallinity peak value is the ratio of the integral value of the CuPc crystallinity peak after the accelerated high temperature standing to the integrated value of the CuPc crystallinity peak before the accelerated high temperature standing. Is larger than 1, the crystallinity of the CuPc film is high by accelerating high temperature standing, and less than 1 is low.

The V-I characteristic shift amount is based on the V-I characteristic before accelerated high temperature standing and the V after the accelerated high temperature standing.
It shows how many volts the I characteristic has shifted.
Specifically, in FIG. 9 above, the ratio of the CuPc crystallinity peak was 1.5, and the crystallinity changed significantly, so that as shown in FIG. 8 above, the VI characteristic shift amount was as large as about 3V. Was becoming.

Further, in FIG. 6, "conditions for pretreatment for cleaning"
Is the ITO film 20 formed on the glass substrate 10
It is a condition for cleaning before forming the Pc film 30, and “plasma” is the plasma cleaning process of the above-mentioned argon and oxygen, “UV”.
"300 ℃", "UV250 ℃", "UV150 ℃",
“UV normal temperature” means a treatment in which ultraviolet irradiation is performed at each temperature. Further, in FIG. 6, “material heating temperature” is the material temperature at the time of forming the CuPc film 30.

Further, in FIG. 6, "film forming method" shows the condition in the case where the third manufacturing method is adopted. “Post-deposition heating (in vacuum at 150 ° C.)”, “Post-deposition heating (in vacuum at 100 ° C.)”, and “Post-deposition heating (in vacuum at 70 ° C.)” are specific examples of the above-described third manufacturing method. This is the case of Example 1, Example 2 and Example 3.

The organic EL shown in the graph of FIG. 5 has an X-ray diffraction peak ratio of 1.25 and a VI shift of 1.6V.
The uneven brightness was not clearly recognized in the device. However, in the organic EL device having the X-ray diffraction peak ratio of about 1.3 and the VI shift of about 2.0 V, the uneven brightness was clearly recognized.

From the above, it can be said that the threshold value of the X-ray diffraction peak ratio is about 1.25 and the threshold value of the VI shift is about 1.6 V in view of the commercial property.

That is, as described above, at the CuPc crystallinity peak, the amount of change in the CuPc crystallinity peak value due to heating within the operating temperature (for example, -40 ° C to 120 ° C) of the organic EL element S1 before heating is determined. By suppressing the CuPc crystallinity peak to be within ± 25%, it is possible to prevent current short circuit and leakage within the operating temperature, and to realize good luminance characteristics at a practical level.

Further, from FIG. 6, if the heat treatment temperature of the ITO film 20 is set to 250 ° C. or higher, it is possible to effectively reduce the adsorbed water and the bound water on the surface of the underlying ITO film. It can be seen that an organic material having enhanced crystallinity can be formed into a film in order to achieve the above.

The change in the CuPc crystallinity peak value due to heating may or may not decrease in the increasing direction. That is, the amount of change may be + 25% or less or -25% or more of the CuPc crystallinity peak before heating, and as shown in FIG. 5, the X-ray diffraction peak ratio is 0.
It may be 75 or more. For example, the X-ray diffraction peak ratio is 0.6
In the case of 8, the VI shift was 2.8 V, and the uneven brightness was recognized.

In the structure and manufacturing method applied to the CuPc film, that is, the hole injection layer 30, the organic material forming the hole transport layer 40, the light emitting layer 50, the electron transport layer 60, and the electron injection layer 70 is crystalline. These layers 4 if
It can also be applied to 0 to 70.

[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 shows T just after forming an ITO film on a glass substrate.
It is a figure which shows a DS spectrum.

FIG. 3 is a diagram showing a TDS spectrum of a surface of an ITO film when heat-treated at a temperature of 300 ° C. in a nitrogen atmosphere.

FIG. 4 is a diagram showing a TDS spectrum of the surface of an ITO film when heat-treated in vacuum at a temperature of 300 ° C.

FIG. 5 is a diagram showing a relationship between a ratio of CuPc crystallinity peaks and a VI characteristic shift amount before and after being left at a high temperature of 120 ° C. for 2 hours.

FIG. 6 is a chart showing the underlying data of FIG.

FIG. 7 is a diagram showing an estimated structure of an amorphous state and an estimated structure of a crystalline state in a conventional organic material.

FIG. 8: 100 ° C., 12 h in a prototype of the present inventors
It is a figure which shows the mode of VI characteristic shift before and after leaving to stand at high temperature by r.

FIG. 9: 100 ° C., 12 h in a prototype of the present inventors
It is a figure which shows the X-ray-diffraction spectrum of the CuPc film before and after leaving to stand at high temperature by r.

[Explanation of symbols]

10 ... Substrate, 20 ... ITO film (anode), 30 ... CuPc
Film (hole injection layer), 40 ... Hole transport layer, 50 ... Light emitting layer,
60 ... Electron transport layer, 70 ... Electron injection layer, 80 ... Cathode.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 7, 2003 (2003.3.7)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

[0031] That is, in the invention described in claim 1, moth
Use of an organic EL device having at least one crystalline organic material having no Lath transition temperature, the value of a diffraction peak of the organic crystalline material showing by an X-ray diffraction method. Within the temperature range of -40 ℃ to 1
The variation of the diffraction peak value by heating within 20 ° C., characterized by being within ± 25% of the diffraction peak value before heating. Here, the crystallinity includes microcrystals.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

Here, as in the invention described in claim 2,
When an ITO film made of indium-tin oxide is formed on the substrate , the organic thin film exhibiting crystallinity is
It to what is formed on the O film.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Further, as in the invention described in claim 3,
The organic thin film exhibiting crystalline characteristics can be a copper phthalocyanine film, and in this case, the diffraction peak value is the diffraction peak value of the (200) plane parallel to the substrate in the copper phthalocyanine film.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Further, in the invention according to claim 6, on the substrate
An ITO film made of indium-tin oxide is formed on
Has no glass transition temperatureCrystalline organicThin film
For manufacturing an organic EL device by forming a film on an ITO film
The surface of the ITO film before depositing the organic material.
It is characterized in that the bound water of is removed.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

Here, in the invention described in claim 2 and claim 4, as in the invention described in claim 5,
The organic thin film having crystallinity may be formed directly on the ITO film. That is, it is possible to adopt a configuration in which an organic thin film exhibiting crystallinity and ITO film is in contact directly.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

Further, in the invention according to claim 9, an ITO film made of an oxide of indium-tin is formed on the substrate,
Organic thin films that do not have a glass transition temperature but exhibit crystalline characteristics
A method of manufacturing an organic EL device, comprising forming a film on an ITO film, wherein the ITO film is formed on the ITO film before forming the organic material.
The heat treatment is performed at a temperature of 50 ° C. or higher.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0047

[Correction method] Change

[Correction content]

According to the tenth aspect of the present invention, an ITO film made of indium-tin oxide is formed on a substrate, and an organic thin film having no glass transition temperature but exhibiting crystalline characteristics is formed by the ITO film. a manufacturing method of an organic EL element formed by forming on the, after the organic thin film exhibiting crystallinity was formed on the ITO film, followed by heating in a vacuum or in an inert gas atmosphere, the It is characterized in that film formation of an organic material exhibiting crystallinity is completed.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction content]

In each of the above manufacturing methods, ITO is also used.
An organic thin film having crystallinity can be formed directly on the film. That is, it is possible in which an organic thin film exhibiting crystallinity and ITO film is deposited in direct contact.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Delete

Continued front page    (72) Inventor Masaaki Ozaki             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 3K007 AB02 AB03 AB08 AB11 AB13                       AB14 AB17 CB01 CB04 DB03                       FA03

Claims (12)

[Claims] 1. An organic EL element comprising at least one organic material exhibiting crystallinity, wherein a value of a diffraction peak of the organic material exhibiting crystallinity which is obtained by an X-ray diffraction method indicates a temperature at which the organic EL element is used. The organic EL element, wherein the amount of change in the diffraction peak value due to heating inside is within ± 25% of the diffraction peak value before the heating. 2. An ITO film made of an oxide of indium-tin is formed on a substrate, and the organic material exhibiting crystallinity is configured as an organic film formed on the ITO film. The organic EL according to claim 1, characterized in that
element. 3. The organic material exhibiting the crystalline characteristic is a copper phthalocyanine film, and the diffraction peak value is a diffraction peak value of a (200) plane parallel to the substrate in the copper phthalocyanine film. The organic EL element according to claim 2. 4. An ITO film made of an indium-tin oxide is formed on a substrate, and an organic material exhibiting crystallinity is added to the I film.
An organic EL device formed on a TO film, wherein the ITO film has no bound water peak at around 330 ° C. in the spectrum of water content measured by the temperature programmed desorption method. Organic E characterized by being
L element. 5. The organic EL device according to claim 2, wherein the organic material exhibiting the crystallinity is formed directly on the ITO film. 6. An ITO film made of an indium-tin oxide is formed on a substrate, and an organic material exhibiting crystallinity is added to the I film.
A method of manufacturing an organic EL element formed on a TO film, wherein the bound water on the surface of the ITO film is desorbed before forming the organic material. Device manufacturing method. 7. In a spectrum of water content measured by a temperature programmed desorption method on the surface of the ITO film after the desorption treatment, the peak value of bound water near 330 ° C. is the ITO before the desorption treatment. The method for producing an organic EL device according to claim 6, wherein the value is within 50% as compared with the bound water peak value on the surface of the film. 8. The bound water peak at around 330 ° C. is eliminated in the spectrum due to water measured by the temperature programmed desorption method on the surface of the ITO film after the desorption process. Item 8. A method for manufacturing an organic EL device according to item 7. 9. A method for manufacturing an organic EL device, comprising forming an ITO film made of an oxide of indium-tin on a substrate and forming an organic material exhibiting crystalline characteristics on the ITO film. Then, before depositing the organic material, deposit the ITO film at 250 ° C.
A method for manufacturing an organic EL element, which comprises performing heat treatment at the above temperature. 10. A method of manufacturing an organic EL device, comprising forming an ITO film made of an oxide of indium-tin on a substrate and forming an organic material exhibiting crystallinity on the ITO film. After forming a film of the organic material exhibiting crystallinity on the ITO film, heat treatment is performed in a vacuum or an inert gas atmosphere to complete the film formation of the organic material exhibiting crystallinity. A method for manufacturing a characteristic organic EL element. 11. The method for manufacturing an organic EL device according to claim 10, wherein the temperature of the heat treatment is 70 ° C. or higher. 12. The organic material exhibiting the crystallinity is the IT
The method for manufacturing an organic EL device according to claim 6, wherein the film is formed directly on the O film.