JP2003173873A - Manufacturing method of organic el element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a generation of dark spots on a protection film caused by an aging process applied to an organic EL element to which, the protection film is formed and the aging is carried out in order to stabilize a brightness property. <P>SOLUTION: For the manufacturing method of the organic EL element forming a lamination body by successively laminating a lower electrode, an organic layer including a light emitting layer, and an upper layer on a substrate, and covering the lamination body by a protection film, an aging process, impressing a current between the lower electrode and the upper electrode, is applied after forming the lamination body on the substrate, and the protection film is formed after the aging process. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Organic EL (electroluminescence)
And a method for manufacturing the element. [0002] 2. Description of the Related Art An organic EL device is mounted on a substrate such as glass.
The lower electrode, the organic layer including the light emitting layer, and the upper electrode
It is formed by forming a laminated body which is sequentially laminated. Where the organic layer
In addition to the light emitting layer, the positive
Light is emitted from the hole transport layer for transporting holes and the other electrode
An electron transport layer for transporting electrons to the layer is formed.
You. [0003] Then, holes and electrons are transferred from the upper and lower electrodes to the light emitting layer.
Inject electrons and recombine these holes and electrons in the light-emitting layer.
And emit light using the energy at that time.
I have. In addition, in the organic EL element, the laminate is externally provided.
A protective film to protect the laminate from moisture and foreign matter
Usually, it is provided so as to cover. Further, luminance characteristics of a laminate including a light emitting layer
Before shipment for the purpose of stabilizing the characteristics of organic EL elements.
That is, in the manufacturing process, between the lower electrode and the upper electrode
Considering the aging process of applying current
I have. In other words, the aging step is based on the use of the organic EL element.
Of element destruction roughly classified into initial destruction and wear destruction
Premature initial destruction of the state is excluded
It is a process. An organic EL device having such a protective film is
Regarding aging in, for example, JP-A-8-18
A method described in Japanese Patent No. 5979 has been proposed. This public
According to the report, after forming a protective film on the organic EL element,
The above laminate was formed on a substrate, and a protective film was formed thereon
Later, aging can be performed to stabilize the characteristics.
Proposed. [0006] SUMMARY OF THE INVENTION However, the present invention
According to the study by the people and others, the aging described in the above-mentioned conventional gazette
In the manufacturing method that performs
It was found that there was a limit to the suppression of dark spots. This
Here, a dark spot is defined by moisture in the operating environment.
This is a non-light-emitting portion formed by: The present inventors have proposed an organic EL device having a protective film.
After aging was performed after forming the
Frequent occurrence of dark spots relatively early after
The degree has increased. Therefore, the starting point of the dark spot is described in detail.
After examination, the cause of the origin is usually easily
Poor pinholes and poor shape coverage as expected.
It turned out that it was not only due to the parts that did not. In other words, when aged,
Initial destruction of the organic EL element due to film quality change or foreign matter
However, many of the dark spots start from this element
This is due to cracking of the protective film due to the impact at the time of breakage.
It became clear. [0010] Specifically, the center of the crack in the protective film is heat
Degraded as if melted, tens of μ from the center
cracks spread radially over m
Met. This part becomes an entry path for moisture etc.
Obviously, this leads to the occurrence of a work spot. As described above, from the above examination, it was found that
The dark spot presumed to be
The part with good coverage is the initial fracture mode during aging.
It is concluded that this occurred due to the occurrence of a code. In view of the above problems, the present invention forms a protective film.
And aging to stabilize the luminance characteristics, etc.
In the method of manufacturing an organic EL device to be performed,
To reduce the occurrence of dark spots on the protective film
Aim. [0013] Means for Solving the Problems The invention according to claim 1
Is based on the findings obtained by the above-mentioned studies by the present inventors.
The lower power supply was placed on the substrate (1).
Electrode (2), organic layer including light emitting layer (5), and upper electrode
(7) is sequentially laminated to form a laminate (8).
Organic E in which the laminate of the above is covered with a protective film (9).
In a method for manufacturing an L element, a laminate is formed on a substrate.
Then apply an electric current between the lower and upper electrodes.
Perform a aging process, and after this aging process,
It is characterized by forming. As described above, the aging process is
Preliminarily caused initial destruction in the use of organic EL elements.
This is the process of exposing the garbage and excluding it. In the present invention, the element
Before forming a protective film by forming a laminate to be the light emitting portion of
Aging the laminate to cause the initial fracture
Will be. [0015] Then, in advance, the laminate
Aging because a protective film is formed on top
Cracking of the protective film due to initial destruction does not occur. But
Thus, according to the present invention, the protection film due to aging
Manufacturing method capable of reducing occurrence of dark spots
Is provided. The symbols in parentheses of the above means are described later.
Showing the correspondence with the specific means described in the embodiment.
It is an example. [0017] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Will be described. FIG. 1 shows an embodiment according to the present invention.
FIG. 4 is a schematic cross-sectional view showing one structural example of a device EL element S1. On a glass substrate 1 as a substrate, a lower part
ITO film 2 as electrode, CuPc as hole injection layer
(Copper phthalocyanine) film 3, aromatic as hole transport layer
Tertiary amine film 4, Alq (8-hydroxy
(Shiquinoline aluminum complex) film 5, as electron injection layer
LiF (lithium fluoride) film 6 as upper electrode
An Al (aluminum) film 7 is formed. Here, ITO (oxidation of indium and tin)
Material) The film 2 is configured as an anode, the Al film 7 is configured as a cathode, and Li
The F film 6 is configured as a part of the cathode. And book
In the example, each of the layers 3 to 5 sandwiched between the electrodes 2 and 7 is an organic layer.
It is configured as And these electrodes and organic
The layers 8 constitute a laminate 8. On the glass substrate 1, the above-mentioned laminate
Alumina (Al) as a protective film so as to cover
_TwoO_Three) A film 9 is formed. The alumina film 9
The laminate 8 is protected from moisture and foreign matter from outside.
You. In such an organic EL element S1,
By applying an electric field to the upper and lower electrodes 2 and 7, the ITO film is formed.
2 from the Al film 7 into the Alq film 5,
Electrons are injected into the film 5 and these holes and electrons are transferred to the Alq film 5.
And recombine, and light is emitted by the energy at that time.
It has become so. The organic EL device according to this embodiment is
In addition to the above-described FIG.
The organic layer including the layer and the upper electrode are sequentially laminated
A laminate is formed, and the laminate is covered with a protective film.
What is necessary is just a structure. In addition, each layer of the laminate and protection
Used for ordinary organic EL devices as a film material constituting the film
Used in organic EL devices
It is sufficient if it is a material with a limitation, and it is limited to the film material shown in FIG.
It is not done. Next, the organic EL element S1 shown in FIG.
Manufacturing method of organic EL device of the present embodiment based on configuration
Is described. FIG. 2 shows a process chart of this manufacturing method. After cleaning the glass substrate 1, a sputtering method or the like is used.
To form an ITO film 2. And the table of ITO film 2
Polish the surface. After that, each layer 3 to 7 is formed on the ITO film 2.
A film is formed to form a laminate 8. Specifically, a glass substrate 1 with an ITO film
Is set in a film forming apparatus, and a CuPc film is formed on the ITO film 2.
3 is, for example, an aromatic tertiary amine film 4 having a thickness of 15 nm.
If the Alq film 5 has a thickness of, for example,
The iF film 6 is, for example, 0.5 nm in thickness, and the Al film 7 is, for example, a film.
In order to achieve a thickness of 150 nm, vacuum evaporation
To form a film. The substrate 1 on which the laminate 8 is formed in this manner is
It is completed. Hereinafter, this is referred to as a film formation substrate 1. Next, an aging step is performed. That is,
The film forming substrate 1 is placed in the film forming apparatus without opening to the atmosphere.
Conveyed to the glove box connected to the device. In this glove box, dry nitrogen
It is filled with a mixed gas of oxygen. Its dew point is preferable
Is preferably −80 ° C. or less. This is all dark spots
It is a condition that does not grow or grow. At least as an upper limit
-50 ° C is a standard. The dew point is, for example, about 10 hr.
In this case, the exposure time to the
Spots are generated, but the emission area is reduced
The fraction can be made extremely small. Of course
The dark spot growth is exposed to the aging atmosphere
Exposure to aging atmosphere as it grows over time
The shorter the dew time, the worse (higher) the dew point.
It is possible in principle. On the other hand, the oxygen concentration is at least 1% or more and 1%.
0% or less is desirable. Aging effect is less than 1%
become weak. Specifically, frequent short-circuits between the cathode and anode
And it is difficult to cause the desired initial fracture.
It becomes difficult. On the other hand, if it exceeds 10%, the dark spot
Growth becomes remarkable. But this is also a dew point
Like, it depends on the exposure time to the aging atmosphere
The higher the oxygen concentration, the shorter the aging time
It is possible in principle. The glove box has a power supply
And electrodes 2 and 7 on the film forming substrate 1 through the probe pins
Lighting jig that can make electrical connection is provided
And the light emitting layer on the film forming substrate 1 in the glove box
5 can be turned on. In this example, the glove box
The driving conditions in the aging process were determined as follows.
The rationale is to apply a higher load than the driving conditions in the market
The conditions were set so that the initial destruction mode could be removed. Specifically
Is 1/6 of the reverse bias 16V which is the driving condition in the market.
Aging condition is reversed via 4 duty drive.
5V overload, such as 21V, aging
The time was set to 10 minutes. This eliminates the initial destruction mode.
Was. This was determined from the Weibull plot. Note that this
The aging condition is arbitrary as long as the initial failure mode can be removed.
The reverse bias and the driving waveform are not limited to these. Subsequently, after the aging step, aging
The deposited film forming substrate 1 is placed in the film forming apparatus without opening to the atmosphere.
It is transported to the protective film deposition chamber, which is one of the chambers. And this
In the protective film forming chamber, the alumina film 9 as the protective film is AL
E (Atomic Layer Epitaxy) method
A film having a thickness of 120 nm was formed. Specific film forming conditions are as follows.
You. The chamber for forming the protective film is evacuated to about 40 Pa,
N_TwoThe substrate is heated while flowing gas at about 400 sccm,
The substrate temperature was stabilized at 100 ° C. After that, TMA
Limethyl aluminum) and H_TwoO in the raw material bottle
At room temperature and the carrier gas N_TwoGas 400s
It was alternately introduced into the reactor at ccm. [0036] The gas to the reactor is first vaporized TMA.
After introducing for 0.6 sec, other than molecules adsorbed on the substrate surface
Purge to remove excess TMA present in the gas phase
As N_TwoGas was introduced for 2.4 sec. Then similar
To vaporize H_TwoO for 1.0 sec, N _TwoPurge is 4.0 sec
The film was formed for a gas introduction time of This TMA introduction → purge → H_TwoO introduction → pa
The cycle of page was repeated 1500 times to form a film. This
During the reaction, the pressure of the reactor is 150 to 300 Pa,
The temperature was kept at 100 ° C. by a heater in the reactor.
The protective film formed at 80 ° C. has a very high moisture permeability.
High and did not function as a protective film to prevent humidity. One
That is, the film formation temperature is 80 ° C. or higher and the Tg point of the organic layer material or lower.
Is desirable. After the film formation is completed, N_Two400 s of gas
The substrate was cooled while being introduced while the substrate temperature was 70 cm.
When the temperature reaches ℃, the reactor is brought to atmospheric pressure and the substrate is taken out
Was. By this method, an Al film having a thickness of about 120 nm is formed._TwoO_ThreeGet
Was done. Incidentally, regarding the formation of the protective film,
Method, protective film, etc.
A film forming method such as CVD or thermal CVD may be used for protection.
The film may be titania, silicon nitride, or the like. The protective film forming chamber and the above film forming apparatus are large.
Structured so that there is no need to open
But it is necessary to open to the atmosphere due to equipment limitations.
There may be cases. In that case, finish the aging process
After the work is taken out into the atmosphere, the protective film
What is necessary is just to move to a membrane chamber. As a guide, about 10 minutes
It is desirable to complete the moving operation in the meantime. As described above, according to the present manufacturing method, the substrate 1
After forming the laminate 8 on the lower electrode 2 and the upper electrode 7
An aging step of applying a current between the
By forming the protective film 9 after the aging step,
The organic EL element S1 of the present embodiment is completed. By the way, according to the above manufacturing method, the device
A laminate 8 to be a light emitting portion is formed, and a protective film 9 is formed.
Before doing the initial destruction in the use of organic EL devices,
Perform an aging process that generates and excludes
are doing. Therefore, protection due to initial destruction during aging
No cracking of the protective film 9 occurs. Therefore, in aging
The occurrence of dark spots on the protective film 9 due to
A possible manufacturing method is provided. Specifically, a protective film 9 is formed before aging.
And a protection film 9 after aging.
A drive evaluation test was performed on the film-formed device of this embodiment with the device of the present embodiment.
Carried out. The device as the comparative example is a device shown in FIG.
Process diagram, that is, based on the conventional organic EL element manufacturing process
Created. That is, the glass substrate 1 is cleaned and the ITO film
2 is formed, and the ITO film 2 is polished.
To 7 to form a laminate 8, on which a protective film 9 is formed.
After forming, aging is performed to create a device of the comparative example
did. According to the driving evaluation test, in the comparative example,
Dark spots occurred frequently within 50 hours after the start of evaluation
In contrast, in the present embodiment, even after 500 hours have elapsed,
No spots were found. Further, in the manufacturing method of the present embodiment described above,
Before the protective film is formed,
Has been implemented. As a result, the cathode metal
Since the cathode 7 is exposed to the atmosphere, the cathode 7 is oxidized on the surface of the cathode 7.
Can be insulated, and when the initial destruction mode occurs,
The effect that the short circuit between the cathode 7 and the anode 2 can be prevented.
There is fruit. Conversely, before aging, as in the conventional manufacturing method
Probability that the short circuit will occur if a protective film is formed
Will be higher.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing an organic EL device according to an embodiment of the present invention. FIG. 2 is a process chart showing a method for manufacturing the organic EL device of the embodiment. FIG. 3 is a process chart showing a manufacturing process of a conventional organic EL element. [Description of Signs] 1 ... Glass substrate, 2 ... ITO film as upper electrode, 5 ...
An Alq film as a light emitting layer, 8 ... a laminate, 9 ... alumina film as a protective film.

Claims (1)

Claims: 1. A laminate (1) comprising a substrate (1), a lower electrode (2), an organic layer including a light-emitting layer (5), and an upper electrode (7) sequentially laminated. 8), wherein the laminated body is covered with a protective film (9). In the method for manufacturing an organic EL device, the laminated body is formed on the substrate, and then the lower electrode and the upper electrode are formed. An aging step of applying a current between the steps, and forming the protective film after the aging step.