JP2003217829A - Organic el display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device panel capable of reducing the size and thickness of a sealing structure by thin film sealing, and restraining deterioration of an organic EL element due to entering of moisture or the like from the outside so as to secure enough durability. <P>SOLUTION: In this organic EL display panel 11, the organic EL element 16 where a first electrode layer 13, an organic EL layer 14 and a second electrode layer 15 are stacked in order is formed on the surface of a transparent or a translucent substrate 12. In the organic EL element 16, the surface outside of the surface opposite to the base plate 12 is coated with a sealing film 17. The sealing film 17 is composed of a passivation film 18 and a moisture absorbing layer 19 formed on the inside thereof. The passivation film 18 is composed of a metal film 18a and a ceramic film 18b, and the metal film 18a is formed outside. The metal film 18a is formed of aluminum, and the ceramic film 18b is formed of silicon nitride, and the moisture absorbing layer 19 is formed of magnesium oxide. <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 electroluminescence (hereinafter simply referred to as "organic EL") display panel, and more particularly to an organic EL display panel provided with a sealing film (protective film) covering an organic EL element.

[0002]

2. Description of the Related Art An organic EL element has an organic EL layer formed between a first electrode (anode) and a second electrode (cathode).
Since the organic EL material has high reactivity with oxygen and moisture, if it is not used in a state of being shielded from the outside air, chemical degradation occurs due to oxygen and moisture in the atmosphere, and a problem that a non-luminous area called a dark spot expands. is there. As a method for practically cutting off the organic EL layer from the outside air, a method of putting a cover made of stainless steel or glass on the substrate via an adhesive and accommodating an adsorbent in the cover to seal the cover is used. There is something. In this configuration, moisture or the like hardly enters from the cover body portion, but moisture or the like enters from the adhesive portion. However, since the invading water and the like are adsorbed by the adsorbent, the deterioration of the organic EL element is suppressed.

Further, Japanese Patent Application Laid-Open No. 9-35868 discloses that
An organic EL element formed on a glass substrate is covered with a housing material fixed on the substrate with an epoxy resin, and an inert liquid containing an adsorbent is provided in a space formed by the housing material and the glass substrate. What is filled with is disclosed. Also in this configuration, moisture or the like enters from the adhesive portion, but since the entered moisture or the like is adsorbed by the adsorbent, deterioration of the organic EL element is suppressed.

As a method of sealing an organic EL element, a method of sealing an organic EL element with an inorganic passivation film such as silicon nitride or silicon oxide has also been disclosed (for example, Japanese Patent Laid-Open No. 2000-223264).

[0005]

However, in the method of providing a cover made of stainless steel or glass on a substrate with an adhesive or the method disclosed in Japanese Patent Application Laid-Open No. 9-35868, deterioration of an organic EL element is suppressed. Then, there is a problem that the sealing structure becomes large in size in order to secure a space for accommodating the adsorbent sufficient to secure the durability.

On the other hand, the organic EL is formed by the inorganic passivation film.
In the method of sealing the element, the structure for sealing can be made thin, but in order to suppress the entry of water and the like and secure sufficient durability, it is necessary to increase the film thickness. The thicker the film, the longer the manufacturing time and the higher the cost.

The present invention has been made in view of the conventional problems described above, and an object of the present invention is to make a sealing structure small and thin by thin film encapsulation, and to realize an organic EL element by the intrusion of moisture or the like from the outside. An object of the present invention is to provide an organic EL display panel capable of suppressing deterioration and ensuring sufficient durability.

[0008]

In order to achieve the above object, in the invention according to claim 1, an organic EL element is formed by stacking a first electrode and a second electrode on a substrate with an organic EL layer interposed therebetween. The surface of the formed organic EL element is covered with a sealing film having a hygroscopic layer formed inside the passivation film. Here, the substrate is not limited to a transparent or semi-transparent simple plate material such as a glass substrate, but includes a panel such as a color filter having a colored pattern for color display or a flexible substrate.

In the present invention, the organic E formed on the substrate
The sealing film that isolates the L element from the outside air (use atmosphere) has a passivation film provided on the side in contact with the outside air to prevent moisture and oxygen from entering. In order to suppress the deterioration of the organic EL element and secure sufficient durability only with the passivation film, the film thickness must be made extremely large, and it takes a long time to form the film, which is not realistic. In the present invention, the passivation film does not completely prevent the invasion of the water or the like, but the film thickness of the passivation film is formed as a film formation time in a realistic short time.
A slight ingress of water is acceptable. However, a small amount of water that has penetrated from the passivation film is adsorbed by the moisture absorption layer,
Deterioration of the organic EL element is suppressed. As a result, the sealing structure can be made smaller and thinner by the thin film sealing, and the organic EL element can be prevented from deteriorating due to invasion of moisture or the like from the outside to ensure sufficient durability.

According to a second aspect of the present invention, in the first aspect of the present invention, the hygroscopic layer is made of at least one substance selected from hygroscopic substances such as magnesium oxide, calcium oxide, barium oxide and aluminum oxide. It is configured. In the present invention, the moisture absorption layer is formed by PVD (Physical Vapor).
It becomes easy to form a thin film layer by the por deposition method or the like.

According to the invention of claim 3, in the invention of claim 1 or 2, the sealing film is formed by vacuum film formation. Here, the vacuum film formation means a method for forming a thin film in a vacuum state or under reduced pressure such as a vacuum vapor deposition method, a sputtering method, an ion plating method, an ion beam method, a CVD method.

In the present invention, since the sealing film is formed by the vacuum film forming method, it is easy to stack and form a plurality of thin film layers forming the sealing film. In the invention described in claim 4, in the invention described in any one of claims 1 to 3,
The passivation film has a metal film as an outermost layer and a silicon nitride film inside thereof.

When the passivation film is made of only silicon nitride, it takes a long time to form a film for securing a necessary film thickness, and pinholes are easily generated. In addition, the impact resistance against external force such as when hit by an object is weaker than that of the metal film. However, in this invention, since the metal film is present in the outermost layer of the passivation film, pinholes are less likely to occur even if the thickness of the passivation film is reduced, and the barrier property of the sealing film is improved. Further, the time for forming the metal film is shorter than the time for forming the silicon nitride film having the same thickness, and the manufacturing time for the entire passivation film can be shortened.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic sectional view of an organic EL display panel. As shown in Figure 1,
The organic EL display panel 11 includes a first electrode layer 13 as a first electrode on a surface of a transparent or semitransparent substrate 12,
An organic EL element 16 is formed by stacking an organic EL layer 14 and a second electrode layer 15 as a second electrode in this order. In this embodiment, the first electrode layer 13 serves as an anode and the second electrode layer 1
5 constitutes a cathode. The surface of the organic EL element 16 is covered with the sealing film 17 except for the surface facing the substrate 12.

The first electrode layer 13 is made of ITO (indium tin oxide) and is transparent. Organic EL layer 14
For example, a known structure is used for the first electrode layer 1
In order from the 3 side, the hole injection layer, the light emitting layer, and the electron injection layer 3
It is composed of layers. The second electrode layer 15 is made of metal (for example,
Aluminum).

In FIG. 1, the first electrode layer 13 and the second electrode layer 1
5 are shown as one plane, for example, when the organic EL display panel 11 is driven by a passive matrix method, the first electrode layers 13 are arranged in a plurality of parallel stripes on the surface of the substrate 12. It is formed. The organic EL layer 14 is formed in a plurality of parallel stripes extending in a direction orthogonal to the first electrode layer 13 in a state of being separated by an insulating partition wall (not shown), and the second electrode layer 15 is the organic EL layer 14 It is laminated on top. And
The organic EL element 16 includes the first electrode layer 13 and the second electrode layer 1
They are arranged in a matrix on the substrate 12 at the intersections of 5.

The sealing film 17 includes a passivation film 18 and
It is constituted by a moisture absorption layer 19 formed inside thereof. The passivation film 18 is composed of a metal film 18a and a ceramic film 18b, and the metal film 18a is formed outside. Therefore, in this embodiment, the sealing film 17 is 3
In the layered structure, the metal film 18a is arranged as the outermost layer, the ceramic film 18b is arranged inside the metal film 18a, and the moisture absorption layer 19 is arranged as the innermost layer. The metal film 18a is made of aluminum, the ceramic film 18b is made of silicon nitride, and the moisture absorption layer 19 is made of magnesium oxide.

Next, a method of manufacturing the organic EL display panel 11 having the above structure will be described. First board 1
A first electrode layer 13 made of ITO is formed on the second layer 2 by sputtering. Next, the organic EL layer 14 and the second electrode layer 15 are sequentially formed on the first electrode layer 13 by vapor deposition. Next, the substrate 12 is transferred into the chamber of the ion plating apparatus without being exposed to the atmosphere, and a moisture absorbing layer of magnesium oxide is formed so as to cover the surface of the organic EL element 16 other than the surface facing the substrate 12. 19 is formed. Next, a ceramic film 18b of silicon nitride is formed so as to cover the moisture absorption layer 19. The formation of the moisture absorption layer 19 and the formation of the ceramic film 18b are both performed at 100 ° C. or lower.

Next, the substrate 12 is transferred into a chamber for vacuum deposition without exposing it to the atmosphere, and the aluminum metal film 18a is coated so as to cover the ceramic film 18b.
To form. The metal film 18a is also formed at 100 ° C. or lower. The above completes the production of the three-layered sealing film 17.

Next, the operation of the organic EL display panel 11 constructed as above will be described. Organic EL layer 14
Deteriorates in the presence of water and oxygen, producing dark spots. In this embodiment, the organic EL element 16 including the organic EL layer 14 is covered with the sealing film 17, so that the moisture, oxygen, and the like in the outside air reach the organic EL layer 14 in order to reach the organic EL layer 14. Need to go through.

Since the conventional sealing film is composed of only the passivation film 18, and the passivation film 18 is thin, it is not possible to completely prevent the permeation of moisture etc. by the passivation film 18 alone. The organic EL layer 14 is deteriorated by the water content and the like. However, since the sealing film 17 of this embodiment is composed of the passivation film 18 and the moisture absorption layer 19, a small amount of water or the like that has passed through the passivation film 18 is adsorbed by the moisture absorption layer 19 and is absorbed by the organic EL layer 14. Do not reach Therefore, even if the sealing film 17 is thinned, the deterioration of the organic EL layer 14 is prevented.

This embodiment has the following effects. (1) The surface of the organic EL element 16 formed of the first electrode layer 13, the organic EL layer 14, and the second electrode layer 15 formed on the substrate 12 is placed inside the passivation film 18 to absorb the moisture.
It was covered with the sealing film 17 on which 9 was formed. Therefore, even a small amount of water that has passed through the passivation film 18 provided on the side in contact with the outside air is not adsorbed by the moisture absorption layer 19 and does not reach the organic EL layer 14, and deterioration of the organic EL element 16 is suppressed. As a result, the sealing structure can be made smaller and thinner by the thin film sealing, and at the same time the organic EL can be protected from the intrusion of moisture from the outside.
It is possible to suppress deterioration of the element 16 and ensure sufficient durability. In addition, only the passivation film 18 is used for organic E
The film forming time can be shortened as compared with the case where the film thickness is set so as to suppress the deterioration of the L element and ensure sufficient durability. Further, when water is present in the organic EL layer 14, the water can be adsorbed by the moisture absorption layer 19.

(2) The sealing film 17 is formed by vacuum film formation. Therefore, it becomes easy to stack and form a plurality of thin film layers forming the sealing film 17. (3) The sealing film 17 is manufactured by a vacuum film forming method under conditions of 100 ° C. or lower. Many currently known EL materials are sensitive to heat and are susceptible to deterioration at temperatures above 100 ° C. However, since the sealing film 17 is formed at 100 ° C. or lower, it is possible to avoid damaging the organic EL layer 14 when forming the sealing film 17.

(4) The moisture absorption layer 19 is made of magnesium oxide. Therefore, it becomes easy to form the moisture absorption layer 19 into a thin film layer by an ion plating method or the like. Further, the moisture absorption layer 19 can be manufactured by the vacuum film forming method under the condition of 100 ° C. or lower,
It is possible to avoid damaging the organic EL layer 14 when forming the moisture absorption layer 19.

(5) The passivation film 18 has a metal film 18a formed on the outermost layer and a ceramic film 18b formed on the inner side thereof. When the passivation film 18 is composed of only the ceramic film 18b, it takes time to form a film to secure a necessary film thickness, and pinholes are likely to occur. In addition, the impact resistance against external force such as when hit by an object is weaker than that of the metal film. However, since the metal film 18a exists in the outermost layer of the passivation film 18, pinholes are less likely to occur even if the thickness of the passivation film 18 is reduced, and the barrier property of the sealing film 17 is improved and the sealing film 17 is formed. Is less likely to be damaged. Further, the formation time of the metal film 18a is shorter than the formation time of the ceramic film 18b having the same thickness, and the manufacturing time of the entire passivation film 18 can be shortened.

(6) The ceramic film 18b is made of silicon nitride. Therefore, the ceramic film 18b can be manufactured by the vacuum film forming method under the condition of 100 ° C. or less, and the organic EL layer 14 can be prevented from being damaged when the ceramic film 18b is formed.

(7) The sealing film 17 is the organic EL element 16
Side, that is, the substrate 12 side, the moisture absorption layer 19, the ceramic film 18
It has a three-layer structure in which b and the metal film 18a are laminated in this order. Therefore, the organic EL element 16 due to invasion of moisture or the like from the outside
It is possible to easily manufacture the thin sealing film 17 capable of suppressing the deterioration of No. 1 and ensuring sufficient durability.

(8) The metal film 18a is aluminum,
The ceramic film 18b is made of silicon nitride, and the moisture absorption layer 19 is made of magnesium oxide. Therefore, the thin sealing film 17 capable of suppressing the deterioration of the organic EL element 16 due to invasion of moisture or the like from the outside and ensuring sufficient durability can be easily manufactured at 100 ° C. or lower.

The embodiment is not limited to the above, but may be configured as follows, for example. The passivation film 18 is not limited to the composite structure of the metal film 18a and the ceramic film 18b.
It is also possible to eliminate a and form only the ceramic film 18b, or to form a resin passivation film on the outside of the ceramic film 18b instead of the metal film 18a.

The material of the ceramic film 18b is not limited to silicon nitride, and other materials having a low permeability of gas such as moisture and oxygen, for example, silicon oxide or diamond-like carbon may be used. Further, the ceramic film 18b may be formed by laminating thin films made of different materials.

The substance forming the hygroscopic layer 19 is not limited to magnesium oxide, and metal oxides such as calcium oxide, barium oxide, aluminum oxide and strontium oxide, and other hygroscopic substances may be used. Further, the moisture absorption layer 19 may be composed of a layer in which a plurality of substances are mixed.

The first electrode layer 1 disposed on the substrate 12 side
3 may be a cathode and the second electrode layer 15 may be an anode. In this case, the structure of the organic EL layer 14 is also changed correspondingly. A flexible substrate may be used as the substrate 12 instead of the glass substrate.

The substrate 12 is not limited to a transparent or semitransparent simple plate material such as a glass substrate, but may be a color filter having a colored pattern for color display formed on a transparent or semitransparent substrate. When the organic EL element 16 is driven by the active matrix system, a TFT (thin film transistor) may be formed on a transparent or semitransparent substrate.

When a substance having a heat resistance higher than 100 ° C. is used as the organic EL material forming the organic EL layer 14, the formation condition of the sealing film 17 is set to 100 ° C. corresponding to the heat resistance of the organic EL material. The temperature may be exceeded.

When a material having a heat resistance higher than 100 ° C. is used as the organic EL material forming the organic EL layer 14, the formation condition of the sealing film 17 is set to 100 ° C. corresponding to the heat resistance of the organic EL material. The temperature may be exceeded.

The organic EL layer 14 is not limited to the above configuration. ○ Instead of forming the ceramic film 18b by the usual plasma CVD method, ECR (Electron Cyclotron Resonan)
ce) Plasma CVD method may be adopted. In this case, it is possible to form a film at a lower temperature as compared with a normal plasma CVD method, and as the organic EL material forming the organic EL layer 14, a material weaker to heat can be used, and the organic EL material to be used can be freely selected. The degree increases.

In order to form the moisture absorption layer 19, a sputtering method or an ion beam method may be used instead of the ion plating method. The technical idea grasped from the above embodiment will be described below.

(1) In the invention according to any one of claims 1 to 3, the passivation film has a metal film as an outermost layer and a ceramic film inside thereof.

(2) In the invention described in the technical idea (1), the sealing film has a three-layer structure. (3) In the invention according to any one of claims 1 to 4 and the technical idea (1) and (2),
The material forming the sealing film can be formed into a thin film by vacuum film formation at 100 ° C. or lower.

(4) The organic EL device according to the above technical concept (3), wherein the metal film is made of aluminum, the ceramic film is made of silicon nitride, and the moisture absorption layer is made of magnesium oxide.

(5) A method for forming a sealing film covering an organic EL element composed of a first electrode, an organic EL layer and a second electrode formed on a substrate, wherein a moisture absorption layer is first formed by a vacuum film forming method. A method of forming a sealing film for an organic EL device, which comprises forming, then forming a ceramic layer and finally forming a metal layer.

(6) The method for forming a sealing film for an organic EL element according to the above-mentioned technical concept (5), wherein each layer constituting the sealing film is formed at 100 ° C. or lower. (7) The method for forming a sealing film for an organic EL element according to the above-mentioned technical idea (5) or (6), wherein the vacuum film forming method for forming the ceramic layer is a plasma CVD method.

(8) In the invention described in the technical idea (7), the ECR plasma CVD method is used as the plasma CVD method. (9) The method for forming a sealing film for an organic EL device according to the above technical concept (5) or (6), wherein the vacuum film forming method for forming the moisture absorption layer is an ion plating method.

[0044]

As described in detail above, the first to fourth aspects of the invention are described.
According to the invention described in (3), the sealing structure can be made smaller and thinner by the thin film sealing, and the organic EL element can be prevented from deteriorating due to invasion of moisture from the outside and sufficient durability can be secured.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an organic EL display panel according to an embodiment.

[Explanation of symbols]

12 ... Substrate, 13 ... First electrode layer as first electrode, 14
... organic EL layer, 15 ... second electrode layer as second electrode, 1
6 ... Organic EL element, 17 ... Sealing film, 18 ... Passivation film, 18a ... Metal film, 19 ... Hygroscopic layer.

Claims (4)

[Claims] 1. An organic EL element is formed by stacking a first electrode and a second electrode on a substrate with an organic EL layer sandwiched therebetween,
An organic EL display panel in which the surface of the organic EL element is covered with a sealing film having a moisture absorption layer formed inside a passivation film. 2. The organic EL display panel according to claim 1, wherein the moisture absorption layer is composed of at least one substance selected from hygroscopic substances such as magnesium oxide, calcium oxide, barium oxide, and aluminum oxide. 3. The organic EL display panel according to claim 1, wherein the sealing film is formed by vacuum film formation. 4. The organic EL display panel according to claim 1, wherein the passivation film has a metal film formed as an outermost layer and a silicon nitride film formed inside thereof.