JP3531680B2 - Manufacturing method of organic EL device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an organic EL device.

[0002]

2. Description of the Related Art An EL (electroluminescence) element is a light-emitting device that utilizes a phenomenon called electroluminescence or electroluminescence of a solid fluorescent substance. Currently, an inorganic EL element using an inorganic material as a light emitter is practically used. It has been applied to LCD backlights, flat panel displays, etc. However, the inorganic EL element has drawbacks such as a high voltage (up to 200 V) required to emit light from the element and difficulty in colorization. On the other hand, E using an organic material
Research on L-elements has been conducted for a long time, but inorganic E
Since the performance was significantly inferior to that of the L device, full-scale practical research was not reached. But 1987
The organic thin-film EL device proposed by Tang et al. In which the organic material layer is composed of two layers, a hole transport layer and a light emitting layer, is
It has been attracting attention because it realized a high-luminance emission of 1000 cd / m ² or more at a low voltage of 10 V or less by operating with direct current, and in recent years, much research has been actively conducted toward the practical application of a similar organic thin film layered EL element. (CWTang and SAVanSlyke: Appl.Phys.
Lett., 51 (1987) 913).

In the organic EL element as described above, various light emitting devices having various emission wavelengths including blue light emission, which is difficult for the inorganic EL element, have been obtained by changing the light emitting layer material and layer structure. Although it is expected to be applied to a full-color display or a full-color display, deterioration over time is remarkable as compared with an inorganic EL element, and a practical level element has not been obtained.

As one of the examples of improving the light emitting characteristics toward the practical use of the organic EL device as described above, ITO as an anode is used.
It has been reported that the plasma surface treatment of the film as a secondary treatment lowers the emission threshold voltage and suppresses the deterioration of the emission characteristics over time (eg, IEICE Spring Conference Lecture). Proceedings, 5-347, 1993).

[0005]

However, in the organic EL device as described above, there is a problem in that a black dot-like non-light emitting portion appears in the light emitting surface and uniform surface emission cannot be obtained. An object of the present invention is to provide a manufacturing method for manufacturing an organic EL device in which the above problems are improved.

[0006]

To accomplish the above object means to provide a process, as a first invention, on a substrate, an anode, an organic layer, in the manufacturing method of the organic EL element formed by sequentially laminating a cathode, an anode after performing the plasma surface treatment of the ITO film is, without exposing the anode to the atmosphere, then before
On serial anode, the organic compound layer, sequentially forming the cathode, further, sealing
A method for manufacturing an organic EL element for forming a film was used.

As a second invention, in a method of manufacturing an organic EL device in which an anode, an organic material layer, a cathode and a sealing film are sequentially laminated on a substrate, a plasma surface treatment of an ITO film as an anode is performed.
From the process to the formation of the sealing film, without breaking the vacuum
An organic EL element manufacturing method for manufacturing an EL element was used.

[0008]

In the first aspect of the present invention, after the ITO film which is the anode on the substrate is subjected to the plasma surface treatment, the hole transport layer as the organic material layer is continuously formed on the ITO film without exposing the anode to the atmosphere, and the plasma surface is formed. IT cleaned by processing
A light emitting layer as an organic layer without re-contaminating the O film surface ,
A cathode was sequentially formed, and a sealing film was further formed to prevent element change due to oxygen and humidity in the atmosphere.

According to the second aspect of the invention, an organic EL element is manufactured by sequentially stacking an anode, an organic material layer, a cathode and a sealing film on a substrate.
In the manufacturing method, the plasma surface treatment of the ITO film as the anode is performed.
From the processing to the formation of the sealing film, it is possible to prevent the element from changing without breaking the vacuum state, and to manufacture an organic EL element having a small amount of non-light emitting portion.

[0010]

The present invention will be described in detail below with reference to FIG. 1 shown as an embodiment. 1 is a glass substrate, 2 is I as an anode
The TO film is a transparent electrode such as SnO ₂ : Sb or ZnO ₂ : Al. Reference numeral 3 denotes a hole transporting layer as an organic material layer, which has a high hole mobility, a good film-forming property and is transparent, and is preferably, for example, JP-A-4-129191 and JP-A-4-1-1.
The compounds described in JP-A No. 32189 and JP-A No. 4-255692 can be used. Reference numeral 4 denotes a light emitting layer as an organic layer, and any phosphor having fluorescence in the visible region and having good film-forming property can be used, for example, JP-A-4-12919.
1, JP-A-4-132189, JP-A-4-2556.
The compounds described in No. 92 can be used. Reference numeral 5 denotes a cathode, which is preferably a metal or alloy having a small work function, and Mg, MgAg alloy, or the like is a suitable material. Reference numeral 6 denotes a sealing layer, which can be made of SiO ₂ , SiO, GeO or the like for the purpose of preventing oxidation and moisture of the above-mentioned organic material layer and electrode.

The structure of the organic EL device manufactured according to the present invention is not limited to the two-layer device having the hole transport layer 3 and the light emitting layer 4 as described above, but may be a light emitting layer and an electron transport layer. And a three-layer structure of a type including a hole transport layer, a light emitting layer, and an electron transport layer. Commercially available glass substrate with ITO film (Nippon Sheet Glass, P1
1OE-H-PX) ITO film is etched with aqua regia to form an anode pattern, and then the detergent (UAI Kasei Co., Ltd.,
White 7-L) for 1 hour, followed by deionized water for 1 hour, followed by acetone for 30 minutes, followed by ethanol for 1 hour and then in boiling ethanol. Soak for 5 minutes and let it air dry. The cleaned substrate is set on the substrate holder in the film forming apparatus, and the inside of the chamber is depressurized to a vacuum degree of 1 × 10 ⁻⁶ Torr or less.
Subsequently, Ar gas was introduced into the chamber until the pressure reached 3 × 10 ^-2 Torr, and a high frequency voltage was applied for 30 seconds under the condition of 500 watts to reverse-sputter the ITO film substrate to perform plasma surface treatment of the ITO film. .

Subsequently, the inside of the chamber is again regenerated to 1 × 10 ^-6 Torr.
After decompressing to the following vacuum degree, N, N'-diphenyl-N, N '
-Bis (3-methylphenyl) -1,1'-diphenyl-4,4'-
The hole transport layer 3 is formed by using vacuum evaporation of resistance heating method using diamine as a vapor deposition source to form a film of about 500 liters. The deposition rate at this time is about 3Å / s. Subsequently, tris (8-human oxyquinoline) aluminum is used as a vapor deposition source to form a light emitting layer 4 by vacuum vapor deposition of a resistance heating system to form a film of about 500 liters. The deposition rate at this time is about 2Å / s. continue
Using Mg and Ag as vapor deposition sources, co-evaporation is performed by vacuum vapor deposition of a resistance heating method to form a film of about 2300 Å to form the cathode 5. At this time, the ratio of the deposition rate of Mg to Ag is 10: 1, and the deposition rate is about 5Å / s. Finally, about 5000 Å was formed by resistance heating vacuum evaporation using SiO 2 as an evaporation source to form the sealing film 6.

Through the steps described above, an organic EL element is manufactured without breaking the vacuum state from the plasma surface cleaning of the ITO film to the formation of the sealing film 6. When a DC voltage of 15 V was applied to the organic EL device thus obtained, with an ITO film as the anode 2 and an Mg / Ag alloy as the cathode 5, green light emission was obtained, and the number of non-light emitting portions in the light emitting surface was very small. The average luminance of the light emitting surface was 1200 cd / m ² . (Comparative Example 1) After subjecting the anode 2 of the ITO film to plasma surface treatment, the glass substrate 1 with the ITO film was once taken out and was subjected to 3 in the atmosphere.
An organic EL device was manufactured in the same manner as in the example except that it was left for 0 minute, and when a direct current of 15 V was applied in the same manner as the example, green light emission was obtained. However, the average luminance of the light emitting surface was 740 cd / m ² , which was lower than that of the example.

The same glass substrate with an ITO film as that used in the above-mentioned Examples and Comparative Example 1 was ultrasonically cleaned under the same conditions as those in Examples, and immersed in boiling ethanol and then naturally dried. When the composition of the ITO film surface was analyzed using the above, the amount of carbon on the ITO film surface was 32.8%.
However, after performing the plasma surface treatment by reverse-sputtering the ITO film in the same apparatus under the same conditions as in the above example, the amount of carbon was reduced to 3.6%. The cleaning effect of the ITO film surface was confirmed.

However, after this, the glass substrate with the ITO film was taken out from the AES analyzer and allowed to stand in the atmosphere for 30 minutes. Then, the composition of the ITO film surface was similarly analyzed. It increased to the same level as before the surface treatment. From this, it is considered that the present invention makes it possible to fabricate an organic EL element without soiling the surface of the ITO film cleaned by the plasma surface treatment again, and to fabricate an organic EL element having a small amount of unlighted portion. . (Comparative Example 2) After forming the anode 2, the organic material layers 3 and 4 and the cathode 5 on the substrate, the device was once taken out and left in the atmosphere for 30 minutes to make a comparative example, and a direct current of 15 V was applied as in the example. As a result, green light emission was obtained. However, compared to the embodiment, there are many non-light emitting portions in the light emitting surface, and the average luminance of the light emitting surface is 105.
The value was 0 cd / m ^2, which was lower than that of the example.

Oxygen and humidity in the atmosphere are considered to be the cause of deterioration of the organic material layer, interface, and electrode of the organic EL element. According to the present invention, the element is formed after the cathode 5 is formed as in the above-mentioned embodiment. It is considered that by forming the sealing film 6 without exposing it to the atmosphere, alteration of the element due to oxygen and humidity in the atmosphere can be prevented, and an organic EL element with a small amount of unlighted portion could be manufactured.

[0017]

As described above , the IT which is the anode on the substrate is
After the plasma treatment of the O film , the organic material layer is continuously formed on the ITO film without exposing the substrate to the atmosphere. Therefore, the organic EL device is produced without recontaminating the ITO film surface washed by the plasma surface treatment. You can
Further, after forming the cathode, by forming a sealing film without exposing the element to the atmosphere, alteration of the element due to oxygen and humidity in the atmosphere can be prevented, and an organic EL element with a small amount of non-light emitting portion can be manufactured. You can

[Brief description of drawings]

FIG. 1 is a sectional view of an organic EL device manufactured by the method of the present invention.

[Explanation of symbols]

1 glass substrate 2 anode 3 Organic matter layer (hole transport layer) 4 Organic material layer (light emitting layer) 5 cathode 6 Sealing film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideaki Iwanaga               1006 Kadoma, Kadoma-shi, Osaka Matsushitaden               Instrument industry Co., Ltd.                (56) Reference JP-A-5-36475 (JP, A)                 JP-A-5-101889 (JP, A)                 JP-A-5-217673 (JP, A)                 JP-A-5-135877 (JP, A)                 JP-A-5-62523 (JP, A)

Claims (2)

(57) [Claims] To 1. A substrate, an anode, an organic layer, in the manufacturing method of the organic EL element formed by sequentially laminating a cathode, an anode der
After the plasma surface treatment of the ITO film is performed, the anode is exposed to the atmosphere without exposing the anode to the organic layer.
A method for manufacturing an organic EL element, which comprises sequentially forming a material layer and a cathode, and further forming a sealing film . 2. A method for manufacturing an organic EL device comprising a substrate, an anode, an organic material layer, a cathode, and a sealing film, which are laminated in this order,
Forming the sealing film from the plasma surface treatment of the ITO film that is the anode
Manufacture an organic EL device without breaking the vacuum state until completion
A method of manufacturing an organic EL device, comprising: