JP3650366B2 - Organic light emitting device sealed with inorganic material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic light-emitting device in which an organic light-emitting element such as an organic electroluminescence light-emitting element is hermetically sealed, and in particular, an inorganic material sealed with an inorganic sealing layer composed of a composite layer of quartz glass and magnesia is sealed. The present invention relates to an organic light emitting device.
[0002]
[Prior art]
In recent years, research and development of organic electroluminescence elements (organic EL elements) have been promoted in fields such as displays and optical communications. This organic EL element is an element in which a light-emitting layer is formed of an organic low-molecular or low-molecular organic material having EL light-emitting ability, and its characteristics are attracting attention as a self-emitting element. For example, the basic structure is that a film of a hole transport material such as triphenyldiamine (TPD) is formed on a hole injection electrode, and a fluorescent material such as an aluminum quinolinol complex (Alq ₃ ) is laminated thereon as a light emitting layer. Further, a metal electrode having a small work function such as Mg, Li, or Ca is formed as an electron injection electrode.
[0003]
Low molecular weight organic materials such as organic electroluminescence light-emitting elements are vulnerable to moisture and the outside air, and when they come into contact with the atmosphere, non-display defects called dark spots are generated and the defects grow gradually. Resulting in. Therefore, in such an organic light emitting device, it is necessary to hermetically seal the organic light emitting element.
[0004]
Even in a semiconductor element such as an IC chip, it is hermetically sealed for the purpose of protection from the ambient atmosphere, electrical insulation, and the like. Conventionally, plastic sealing with low cost and good workability is often used for sealing semiconductor elements for such purposes. For example, airtight sealing is performed using a polyimide resin or the like.
However, sealing with plastic is inexpensive and has good workability, and has a higher degree of freedom than other sealing methods, but has a disadvantage of poor moisture resistance due to intrusion of moisture. Therefore, it is not suitable for sealing the organic light emitting element as described above.
[0005]
Therefore, in the organic light emitting device, a metal can-like sealing cap is used instead of the resin sealing as described above, and the organic light emitting element is covered with this, and the sealing cap is made of an ultraviolet curable resin with a substrate or a cathode. Adhering airtightly on top is done. In particular, after the organic light emitting device is formed on the substrate, the organic light emitting device is hermetically covered with the sealing cap in a vacuum or a nitrogen gas atmosphere without being exposed to the air. .
[0006]
[Problems to be solved by the invention]
However, the organic light-emitting element sealing means using the conventional sealing cap uses a cap-like device, which increases the volume of the entire apparatus. In particular, there is a problem that the thickness cannot be reduced. Furthermore, a process such as mounting a sealing cap on the substrate in a vacuum or nitrogen gas atmosphere by a manipulator or the like, and further irradiating the ultraviolet curable resin with ultraviolet rays in a vacuum is required. For this reason, there exists a subject that a sealing process is complicated and manufacture takes time.
[0007]
In view of the problems in the conventional means for sealing an organic light-emitting element, the present invention can hermetically seal the organic light-emitting element with a simple process, can be downsized, and has confidentiality and durability. An object of the present invention is to provide a sealed organic light-emitting device capable of obtaining a high airtight state.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention employs hermetic sealing with an inorganic sealing layer such as a deposited film of quartz glass without taking sealing means with resin sealing or a sealing cap. Further, in order to improve mechanical brittleness of the sealing means made of the quartz glass film 9, the inorganic material sealing layer 3 made of a composite film of the quartz glass layer 9 and the magnesia layer 10 is employed.
[0009]
That is, the organic light-emitting device sealed with an inorganic material according to the present invention is formed by hermetically sealing the surface of the organic light-emitting element 2, and the surface of the organic light-emitting element 2 is fused with the quartz glass layer 9 and the magnesia layer 10. Are hermetically covered and sealed with the inorganic material sealing layers 3 laminated alternately.
[0010]
Such an inorganic material sealing layer 3 can be formed by a vapor deposition film. For example, the inorganic glass sealing layer 3 is formed by alternately laminating the quartz glass layers 9 and the magnesia layers 10 by several tens to several hundreds of nanometers by vacuum deposition.
[0011]
The inorganic material sealing layer 3 having the quartz glass layer 9 is superior in airtightness compared to resin sealing using a polyimide resin or the like, and can surely prevent water molecules from entering. However, on the other hand, when the inorganic material sealing layer 3 is formed by the quartz glass layer 9 alone, the quartz glass layer 9 is fragile, so that a fine crack is generated even with a slight impact, and airtightness is easily lost.
[0012]
Therefore, as a result of investigation by the present inventor, the inorganic material sealing layer 3 is not a single layer of the quartz glass layer 9 but a composite layer of the quartz glass layer 9 and the magnesia layer 10, so that it is unique to quartz glass. We focused on improving the brittleness. That is, by using such a composite layer, the inorganic material sealing layer 3 is not easily damaged by an impact.
[0013]
Although the reason or cause is not necessarily clear, the quartz glass layer 9 is amorphous, while the magnesia layer 10 formed by vacuum deposition has cubic crystals. This is presumed to have a buffering action on the quartz glass layer 9.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described specifically and in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an embodiment of an organic light-emitting device sealed with an inorganic material according to the present invention, and FIG.
[0015]
An organic light emitting element 2 is formed on a translucent substrate 1 such as a glass substrate. The organic light emitting device 2 will be briefly described.
First, an anode 4 as a hole injection electrode is formed on a translucent substrate 1. The anode 4 is made of a conductive film that is transparent and has a high work function, such as a film of indium tin oxide (ITO) or polyanine.
[0016]
A buffer layer 5 such as amine (m-MTDATA) or copper phthalocyanine (CuPc) is formed on the anode 4.
A hole transport layer 6 made of a hole transport material such as triphenyldiamine (TPD) is formed on the buffer layer 5. Further, an organic light emitting layer 7 made of organic electroluminescence or the like is formed on the hole transport layer 6. For example, the organic light emitting layer 7 is made of a light emitting material such as 8-quinolinol / aluminum complex (Aiq3) and an electron transport material such as trisaluminum.
[0017]
Further, a cathode 8 made of a conductor having a low work function such as magnesium / silver alloy (Mg—Ag), lithium fluoride (LiF), or aluminum (Al) is formed on the organic light emitting layer 7. The cathode 8 is patterned as necessary. For example, in the case of an organic electroluminescence display, a cathode 8 patterned for each pixel is provided.
[0018]
In the present invention, the inorganic material sealing layer 3 is formed so as to cover the organic light emitting element 2 in an airtight manner. The inorganic material sealing layer 3 is composed of a composite layer in which quartz glass layers 9 and magnesia layers 10 are alternately formed and stacked. First, a quartz glass layer 9 is formed on the translucent substrate 1 so as to cover the organic light emitting element 2, and a magnesia layer 3 is formed thereon. Hereinafter, the quartz glass layer 9 and the magnesia layer 3 are alternately formed. Finally, a quartz glass layer 9 is formed to form the inorganic material sealing layer 3.
[0019]
The film thickness of the quartz glass layer 9 and the magnesia layer 10 is about several tens nm to several hundreds nm, and a total of 5 to 9 layers are laminated. The entire inorganic material sealing layer 3 has a thickness of about 1 to 2 μm.
The inorganic material sealing layer 3 composed of a composite layer of the quartz glass layer 9 and the magnesia layer 10 is formed by vacuum deposition in a vacuum chamber. For example, after forming the organic light-emitting element 2 as described above on the light-transmitting substrate 1 by vacuum deposition in a vacuum chamber, the light-transmitting substrate 1 is not taken out into the atmosphere and sealed with an inorganic material in the vacuum chamber as it is. Layer 3 is formed.
[0020]
FIG. 3 is a schematic view showing a state in which the inorganic material sealing layer 3 is formed by vacuum deposition in a vacuum chamber. The translucent substrate 1 provided with the organic light emitting element 2 is mounted on the substrate holder 16. Quartz glass (SiO ₂ ) 12 and magnesia (MgO) 13 housed in the crucible 11 are focused and irradiated alternately with focused electron beam guns 14 and 15, and the quartz glass 12 and magnesia 13 are alternately evaporated. Then, the molecules are deposited on the light-transmitting substrate 1 and the organic light emitting device 2 thereon. Thereby, the inorganic material sealing layer 3 as shown in FIGS. 1 and 2 is formed.
[0021]
As described above, by using the inorganic material sealing layer 3 as a composite layer of the quartz glass layer 9 and the magnesia layer 10, the inherent brittleness of the quartz glass can be improved. That is, the inorganic material sealing layer 3 is not easily damaged by impact. As described above, this is presumed to be due to the buffering action obtained from the crystal structure of the deposited film of the magnesia layer 10.
In addition, by making the inorganic material sealing layer 3 transparent, an organic light-emitting device that emits light from the inorganic material sealing layer 3 side instead of the light-transmitting substrate 1 side can be obtained.
[0022]
Next, specific examples of the present invention will be described.
(Example 1)
After the organic light emitting element 2 is formed on the translucent substrate 1 made of a glass substrate as described above, the translucent substrate 1 is moved to a substrate holder 16 as shown in FIG. . Then, the quartz glass 12 and the magnesia 13 are alternately evaporated by a vacuum vapor deposition apparatus as shown in the figure, and this is deposited on the light-transmitting substrate 1 and the organic light-emitting element 2 thereon. About 100 nm quartz glass layers 9 and magnesia layers 10 were alternately formed and laminated. Thereby, the inorganic material sealing layer 3 which consists of a total of nine layers of the quartz glass layer 9 and the magnesia layer 10 was formed.
[0023]
Thereafter, the completed organic light emitting device was taken out of the vacuum chamber. The inorganic material sealing layer 3 was transparent, and even if the light-transmitting substrate 1 was lightly tapped with a fingertip to give an impact, no streaks or white turbidity due to cracks occurred. Furthermore, after this organic light emitting device was placed in an environment of a temperature of 80 ° C. and a relative humidity of 90% for 48 hours, when the inside of the inorganic material sealing layer 3 was observed, no moisture permeation was observed.
[0024]
(Example 2)
In Example 1, except that the thickness of the quartz glass layer 9 and the magnesia layer 10 was about 200 nm, and the inorganic material sealing layer 3 composed of a total of five layers of the quartz glass layer 9 and the magnesia layer 10 was formed. An organic light emitting device having the inorganic material sealing layer 3 was manufactured in the same manner as in Example 1.
[0025]
Thereafter, the completed organic light emitting device was taken out of the vacuum chamber. The inorganic material sealing layer 3 was transparent, and even if the light-transmitting substrate 1 was lightly tapped with a fingertip to give an impact, no streaks or white turbidity due to cracks occurred. Furthermore, after this organic light emitting device was placed in an environment of a temperature of 80 ° C. and a relative humidity of 90% for 48 hours, when the inside of the inorganic material sealing layer 3 was observed, no moisture permeation was observed.
[0026]
(Comparative example)
In Example 1, except that the inorganic material sealing layer 3 was not a composite layer of the quartz glass layer 9 and the magnesia layer 10 and the inorganic material sealing layer was formed only by a quartz glass layer having a thickness of about 1 μm. In the same manner as in Example 1, an organic light emitting device having an inorganic material sealing layer was manufactured.
[0027]
Thereafter, the completed organic light emitting device was taken out of the vacuum chamber. The inorganic material sealing layer made of quartz glass was transparent, but when the light-transmitting substrate was lightly hit with a fingertip to give an impact, streaks due to cracks and white turbidity occurred. Further, after placing the organic light emitting device in an environment of a temperature of 80 ° C. and a relative humidity of 90% for 48 hours, when the inside of the inorganic material sealing layer 3 was observed, moisture permeation from the crack was observed.
[0028]
【The invention's effect】
As described above, in the organic light emitting device sealed with the inorganic material according to the present invention, the organic light emitting element can be hermetically sealed by a simple process called vacuum deposition. Moreover, since the inorganic material sealing layer 3 is as thin as 1 to 2 μm, it can be reduced in size as compared with the one using a metal can-like sealing cap. Furthermore, high confidentiality is obtained by the quartz glass layer 9 and the magnesia layer 10, and at the same time, the presence of the magnesia layer 10 improves the brittleness unique to the quartz glass layer 9, thereby obtaining a highly durable airtight seal.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional side view showing an embodiment of an organic light emitting device sealed with an inorganic material according to the present invention.
FIG. 2 is an enlarged view of a portion A in FIG.
FIG. 3 is a schematic side view showing an apparatus for forming an inorganic material sealing layer 3 of an organic light emitting device sealed with an inorganic material according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Translucent board | substrate 2 Organic light emitting element 3 Inorganic material sealing layer 9 Quartz glass layer 10 Magnesia layer

Claims (3)

In the organic light emitting device in which the surface of the organic light emitting element (2) is hermetically sealed, the inorganic light emitting element (2) has an inorganic surface in which quartz glass layers (9) and magnesia layers (10) are alternately stacked. An organic light-emitting device sealed with an inorganic material, wherein the organic light-emitting device is sealed by being hermetically covered with a material sealing layer (3). The organic light emitting device sealed with an inorganic material according to claim 1, wherein the inorganic material sealing layer (3) is made of a vapor deposition film. The inorganic material sealing layer (3) is formed by alternately laminating quartz glass layers (9) and magnesia layers (10) by several tens of nanometers to several hundreds of nanometers, respectively. An organic light emitting device sealed with an inorganic material as described in 1.

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