JP2009123362A - Organic el light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL light-emitting element with high gas barrier properties or sealing characteristics of metal electrodes (4, 5) covering an organic EL film 3. <P>SOLUTION: The organic EL light-emitting element includes a transparent substrate 1, a transparent first electrode 2 formed on a main surface of the substrate 1, an organic EL film 3 formed on the first electrode 2 emitting light by exciton generated by recombination with a hole and an electron injected into an organic compound, and second electrodes (4, 5) formed so as to cover a surface of the organic EL film 3. The second electrodes (4, 5) are provided with a first metal film 4 formed on the organic EL film 3 and a second metal film 5 formed on the first metal film 4. The second metal film 5 is an amorphous or a microcrystal metal film with less possibility that a grain boundary continues or penetrates on a surface and a rear face of the film as compared with a polycrystalline structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an organic EL light emitting device utilizing electroluminescence (EL) of an organic compound.

  The organic EL light emitting element is formed on a glass substrate and is configured by sandwiching an organic EL film between an anode and a cathode. Electrons and holes are injected into the organic compound by the electric field applied by the anode and the cathode, and the organic EL film emits light by excitons generated by recombination of the electrons and holes. The anode or cathode located on the glass substrate side is made of a transparent electrode, and the light of the organic EL film is transmitted to the outside through the transparent electrode and the glass substrate. The electrode on the side facing the transparent electrode is made of a metal electrode such as aluminum.

  Since the organic EL film is easily deteriorated by oxygen and moisture in the air, various methods for blocking the organic EL film from the external environment have been conventionally devised (for example, see Patent Document 1).

In the first method, an organic EL light emitting element and a desiccant are enclosed in a housing formed by bonding glass or a metal tube with a UV curable resin. In the second method, as disclosed in Patent Document 1, a metal oxide film, a metal fluoride film, a Si oxide film, a Si nitride film, or the like is formed on an organic EL light emitting element formed on a glass substrate. An inorganic insulating film such as a Si oxynitride film is covered and sealed. In the third method, the organic EL light-emitting element formed on the glass substrate is covered and sealed with a multilayer film composed of alternately laminated inorganic films and organic films.
JP-A-6-96858

  Since these sealing methods have a complicated structure and require a large number of steps in order to reliably maintain the element characteristics of the organic EL light emitting element, it takes time and cost to manufacture.

  Since the organic EL film is formed on the glass substrate, if the metal electrode on the side facing the transparent electrode has characteristics (gas barrier properties and sealing characteristics) for shielding the organic EL film from the external environment, the above There is no need to take a method like However, since the crystal grain boundaries composing the metal electrode continuously penetrate the front and back surfaces of the metal electrode in the film thickness direction, oxygen and moisture can easily enter through the crystal grain boundaries, thereby deteriorating the organic EL film. End up.

  Accordingly, an object of the present invention is to provide an organic EL light-emitting device in which the gas barrier property and sealing property of a metal electrode covering an organic EL film are high.

  The first feature of the present invention is that a substrate, a first electrode formed on the main surface of the substrate, an organic EL film formed on the first electrode, and a surface of the organic EL film are provided. An organic EL light emitting device having a second electrode formed to cover the second electrode, wherein the second electrode is formed on the first metal film and the first metal film formed on the organic EL film. And an amorphous second metal film formed.

  According to the first feature of the present invention, since the second metal film is made of amorphous material, the crystal grain boundaries are continuous as compared with the conventional polycrystalline structure, or the crystal grain boundaries penetrate the front and back surfaces of the film. This prevents water molecules and oxygen molecules in the air from passing through the second metal film through the crystal grain boundary and hardly reaching the organic EL film. As described above, the organic EL film is hardly deteriorated by covering the organic EL film with the second electrode having the second metal film having high gas barrier properties and sealing properties. In addition, since the organic EL film is sealed by the second electrode, the heat dissipation is increased and the electric resistance is reduced as compared with the conventional example in which the metal electrode is sealed by the inorganic insulating film or the laminated film of the inorganic film and the organic film. And durability is improved.

  In the first feature of the present invention, the second metal film is formed of a metal compound containing at least one of oxygen and nitrogen in an amount that does not stoichiometrically become a metal oxide, metal nitride, or metal oxynitride. That's fine. As a result, the second metal film becomes an amorphous metal film, and crystal grain boundaries are prevented from being continuous, or the crystal grain boundaries are prevented from penetrating the front and back surfaces of the film.

  For example, the amorphous second metal film is preferably made of an aluminum compound containing oxygen.

  The second feature of the present invention is a transparent substrate, a transparent first electrode formed on the main surface of the substrate, and recombination of electrons and holes formed on the first electrode. An organic EL light emitting element having an organic EL film that emits light by a metal and a second electrode made of a metal formed so as to cover the surface of the organic EL film, wherein the second electrode is formed on the organic EL film A first metal film formed; and a microcrystalline second metal film formed on the first metal film.

  According to the second feature of the present invention, since the second metal film is made of microcrystals, the crystal grain boundaries are continuous as compared with the conventional polycrystalline structure, or the crystal grain boundaries penetrate the front and back surfaces of the film. This suppresses water molecules and oxygen molecules in the air from passing through the second metal film through the crystal grain boundary and hardly reaching the organic EL film. As described above, the organic EL film is hardly deteriorated by covering the organic EL film with the second electrode having the second metal film having high gas barrier properties and sealing properties. In addition, since the organic EL film is sealed by the second electrode, the heat dissipation is increased and the electric resistance is reduced as compared with the conventional example in which the metal electrode is sealed by the inorganic insulating film or the laminated film of the inorganic film and the organic film. And durability is improved.

  In the second feature of the present invention, by forming the second metal film from an alloy of two or more metals, the second metal film becomes a microcrystalline metal film, and crystal grain boundaries are continuous, The boundary is prevented from penetrating the front and back surfaces of the film.

  For example, the alloy of two or more metals is Al—Ta, Al—Ti, Al—Mg, Al—Nd, or Ir—Ta.

  Further, the present invention emits light by a transparent substrate, a transparent first electrode formed on the main surface of the substrate, and recombination of electrons and holes formed on the first electrode. An organic EL light emitting device having an organic EL film and a second electrode formed so as to cover the surface of the organic EL film, wherein the second electrode is a first electrode formed on the organic EL film. It is good also as a structure provided with the metal film, the intermediate film of the film thickness which produces | generates the direct tunnel formed on the 1st metal film, and the 2nd metal film formed on this intermediate film.

  In this case, since the intermediate film has a laminated structure in which the first metal film and the second metal film are sandwiched, the crystal film boundary of the metal film is not continuous by the intermediate film, and the crystal grain boundary is not in the second electrode. It does not penetrate the front and back surfaces. Therefore, water molecules and oxygen molecules in the air hardly pass through the second electrode through the crystal grain boundaries and reach the organic EL film. As described above, the organic EL film is hardly deteriorated by covering the organic EL film with the second electrode having a high gas barrier property and sealing property. In addition, since the organic EL film is sealed by the second electrode, the heat dissipation is increased and the electric resistance is reduced as compared with the conventional example in which the metal electrode is sealed by the inorganic insulating film or the laminated film of the inorganic film and the organic film. And durability is improved.

  For example, the intermediate film is made of aluminum oxide, and the metal film is made of aluminum. The second electrode may further include intermediate films and metal films alternately stacked on the second metal film. This further improves the gas barrier properties and sealing properties of the second electrode.

  In the present invention, the first metal film may be silver or a silver alloy. Further, the first metal film may be a polycrystalline metal film. Further, it is desirable that the planar shape of the organic EL film and the planar shape of the first metal film are the same as viewed from a direction perpendicular to the main surface of the substrate. This same planar shape is obtained by a manufacturing procedure in which an organic EL film and a first metal film are successively formed and simultaneously patterned. Therefore, adhesion of dust can be suppressed between the organic EL film and the first metal film.

  According to the organic EL light emitting device of the present invention, the organic EL film can be covered with a metal electrode having high gas barrier properties and sealing properties.

  Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals.

(First embodiment)
With reference to FIG. 1, the structure of the organic electroluminescent light emitting element concerning the 1st Embodiment of this invention is demonstrated. The organic EL light emitting device includes a transparent substrate 1, a transparent first electrode 2 formed on the main surface of the substrate 1, an organic EL film 3 formed on the first electrode 2, and an organic EL film. And a second electrode (4, 5) formed so as to cover the surface, and an insulating film 6 that electrically insulates between the second electrode (4, 5) and the first electrode 2.

  The second electrode (4, 5) includes a first metal film 4 formed on the organic EL film 3 and an amorphous second metal film 5 formed on the first metal film 4. Is provided. Here, the term “amorphous” generally refers to a material that is not crystalline and has no regularity in the arrangement of solid atoms / molecules. In particular, the film of the second metal film 5 is here. The crystal grain boundaries are not penetrated in the thickness direction. If the crystal grain boundaries are not continuous on the front and back surfaces of the second metal film 5 when viewed macroscopically, the second metal film may be an aggregate of a plurality of crystals when viewed microscopically.

  The planar shape of the organic EL film 3 and the planar shape of the first metal film 4 as viewed from the direction perpendicular to the main surface of the substrate 1 are the same. The outer peripheral portion of the organic EL film 3 is formed on the insulating film 6. The outer peripheral portion of the second metal film 5 is located outside the first metal film 4 and is formed on the insulating film 6. Therefore, the second metal film 5 is formed so as to cover the first metal film 4 and the organic EL film 3.

  The amorphous second metal film 5 is formed of a metal compound containing at least one of oxygen and nitrogen in an amount that does not stoichiometrically become a metal oxide, metal nitride, or metal oxynitride, for example, aluminum containing oxygen. Consists of compounds. As described above, when the metal contains at least one of oxygen and nitrogen in a trace amount, the crystal grain boundary of the metal compound may be disturbed, and the crystal grain boundary may be continuous or the crystal grain boundary may penetrate the front and back surfaces of the film. It is suppressed, and the gas barrier property and sealing property against oxygen and moisture are enhanced. The metal constituting the second metal film 5 may be silver (Ag) in addition to aluminum (Al).

  The first metal film 4 is a film made of a metal such as Al or Ag, an alloy of Al, or an alloy of Ag, and is a polycrystalline metal film formed by vacuum deposition.

  The transparent first electrode 2 is formed of, for example, a translucent indium oxide film doped with tin (ITO film: Indium-tin-oxide). The transparent substrate 1 is formed of a glass substrate or a plastic plate. Alternatively, a flexible sheet or film may be used.

  Although not shown, the organic EL film 3 has a laminated structure of an electron injection layer / electron transport layer / light emitting layer / hole transport layer / hole injection layer. Note that the organic EL film 3 may be configured only by the light emitting layer. The electrode located on the electron injection layer and electron transport layer side forms a cathode, and the electrode located on the hole transport layer and hole injection layer side forms an anode.

  When a voltage is applied between the first electrode 2 and the second electrode (4, 5), electrons and holes are injected from each electrode into the organic EL film 3. The injected electrons and holes pass through the respective electron transport layer / hole transport layer and are combined in the light emitting layer. The light-emitting material of the light-emitting layer is excited by the energy of the bond. Light is generated when returning from the excited state to the ground state again. Since the first electrode 2 is made of a transparent material such as ITO, the light of the light emitting layer is transmitted through the first electrode 2 and the transparent substrate 1, so that light is emitted from the organic EL light emitting element. Since the second electrodes (4, 5) are made of metal, they function as a reflecting mirror.

  In order to increase luminous efficiency, it is desirable to form the cathode with a material having a low work function in order to improve the electron injection property, and to form the anode with a material with a high work function in order to improve the hole injection property. Is desirable. When the second electrodes (4, 5) functioning as a reflecting mirror are cathodes, for example, Al or Ag having a small work function and high light reflectance is desirable, and the second electrodes (4, 4) functioning as reflecting mirrors are desirable. When 5) is an anode, for example, molybdenum or chromium having a high work function and high light reflectance is desirable. In the embodiment of the present invention, the case where the first electrode 2 is an anode and the second electrodes (4, 5) are cathodes will be described.

  Next, a method for manufacturing the organic EL light emitting device shown in FIG. 1 will be described.

  (A) First, a transparent conductive material such as ITO is formed as a first electrode 2 on the main surface of the transparent substrate 1 by vacuum deposition or sputtering, and photolithography and anisotropic etching are performed. Then, the ITO film is patterned into a predetermined shape.

  (B) The insulating film 6 is formed on the first electrode 2, and a predetermined opening is formed in the region of the first electrode 2. Then, the organic EL film 3 is formed on the first electrode 2 and the insulating film 6 exposed from the opening by using a vacuum evaporation method. Subsequently, an Al film is formed as the first metal film 4 on the organic EL film 3 by using a vacuum deposition method. The metal electrode formed directly on the organic EL film 3 is preferably formed by a vacuum deposition method rather than a sputtering method. Damage to the organic EL film 3 can be reduced by using the vacuum deposition method.

  (C) The organic EL film 3 and the first metal film 4 are simultaneously patterned using the photolithography method and the anisotropic etching method so that the outer peripheral portion thereof is disposed on the insulating film 6. Specifically, the organic EL film 3 and the first metal film 4 are selectively removed using the same etching mask.

  (D) A second metal film 5 is formed on the first metal film 4 by sputtering. At this time, a very small amount of oxygen or nitrogen is introduced into the sputtering apparatus so that the second metal film 5 does not become a metal oxide, metal nitride, or metal oxynitride. Thereby, the amorphous second metal film 5 can be formed. Using a photolithography method and an anisotropic etching method, the second metal film 5 is patterned into a predetermined shape so that the outer peripheral portion thereof is disposed on the insulating film 6. The organic EL light emitting device shown in FIG. 1 can be manufactured by the above procedure.

  As described above, according to the first embodiment of the present invention, the following operational effects can be obtained.

  Since the second metal film 5 is made of an amorphous material, it is possible to prevent the grain boundaries from being continuous or penetrating the front and back surfaces of the second metal film 5 as compared with the conventional polycrystalline structure. Water molecules and oxygen molecules in the air are difficult to reach the organic EL film 3 through the second metal film 5 through the crystal grain boundaries. Thus, by covering the organic EL film 3 with the second metal film 5 having high gas barrier properties and sealing properties, the organic EL film 3 is unlikely to deteriorate. In addition, since the organic EL film 3 is sealed by the second electrode (4, 5), it has a higher heat dissipation than the conventional example in which the metal electrode is sealed by an inorganic insulating film or a laminated film of an inorganic film and an organic film. Increases, reduces electrical resistance and improves durability.

  The second metal film 5 is formed of a metal compound containing at least one of oxygen and nitrogen in an amount that does not stoichiometrically become a metal oxide, metal nitride, or metal oxynitride. Becomes an amorphous metal film, and crystal grain boundaries are prevented from being continuous or penetrating through the front and back surfaces of the film.

(Second Embodiment)
In the second embodiment of the present invention, a case where the organic EL film 3 is covered with a microcrystalline second metal film 5 will be described. The cross-sectional structure of the organic EL light emitting device is the same as that in the first embodiment. That is, as shown in FIG. 1, the organic EL light emitting device according to the second embodiment of the present invention includes a transparent substrate 1 and a transparent first electrode 2 formed on the main surface of the substrate 1. An organic EL film 3 formed on the first electrode 2, a second electrode (4, 5) made of metal so as to cover the surface of the organic EL film 3, and the first electrode 2 And the second electrode (4, 5).

  The second electrode (4, 5) includes a first metal film 4 formed on the organic EL film 3 and a microcrystalline second metal film 5 formed on the first metal film 4. Prepare. Here, “microcrystal” indicates a crystal state in which the crystal grain size is larger than that of amorphous and smaller than that of polycrystal. For example, the grain size is about 1/3 of the thickness of the second metal film 5. The microcrystalline second metal film 5 is composed of such an aggregate of crystals.

  The microcrystalline second metal film 5 is formed of an alloy of two or more metals. For example, an alloy of Al and tantalum (Ta), an alloy of Al and titanium (Ti), an alloy of Al and magnesium (Mg), an alloy of Al and neodymium (Nd), or an alloy of iridium (Ir) and Ta The In the microcrystalline second metal film 5 formed of such an alloy, the crystal grain boundaries are disturbed, the crystal grain boundaries are continuous, or the crystal grain boundaries penetrate the front and back surfaces of the second metal film 5. Is suppressed, and gas barrier properties and sealing properties against oxygen and moisture are enhanced.

  The other configuration of the organic EL light emitting device is the same as that of the organic EL light emitting device according to the first embodiment, and a description thereof will be omitted.

  The second metal film 5 is formed on the first metal film 4 by simultaneously performing sputtering using a plurality of metals forming an alloy as a target. Other manufacturing procedures are the same as those in the first embodiment.

  As described above, according to the second embodiment of the present invention, since the second metal film 5 is made of microcrystals, the crystal grain boundaries are continuous as compared with the conventional polycrystalline structure. The boundary is prevented from penetrating the front and back surfaces of the film, so that water molecules and oxygen molecules in the air hardly pass through the second metal film 5 through the crystal grain boundary and reach the organic EL film 3. Thus, by covering the organic EL film 3 with the second metal film 5 having high gas barrier properties and sealing properties, the organic EL film 3 is unlikely to deteriorate. In addition, since the organic EL film 3 is sealed by the second electrode (4, 5), it has a higher heat dissipation than the conventional example in which the metal electrode is sealed by an inorganic insulating film or a laminated film of an inorganic film and an organic film. Increases, reduces electrical resistance and improves durability.

(Third embodiment)
In the third embodiment of the present invention, a case will be described in which an extremely thin intermediate film is formed between the first metal film 4 and the second metal film 5 so as to cause a direct tunnel.

  As shown in FIG. 2, the organic EL light emitting device according to the third embodiment of the present invention includes a transparent substrate 1, a transparent first electrode 2 formed on the main surface of the substrate 1, The organic EL film 3 formed on the first electrode 2, the second electrode (4, 5 a to 5 d) made of metal formed so as to cover the surface of the organic EL film 3, and the first electrode 2 And the second electrode (4, 5a to 5d).

  The second electrodes (4, 5 a to 5 d) are the first metal film 4 formed on the organic EL film 3, the intermediate film 7 formed on the first metal film 4, and the intermediate film 7. And at least a second metal film 5a.

  The intermediate film 7 has such a thickness that a direct tunnel is generated, and is made of an insulating material such as aluminum oxide. “Direct tunnel” refers to a phenomenon in which an insulating film becomes very thin, and electrons penetrate through the insulating film as if passing through the tunnel due to the quantum effect. For example, in the case of silicon oxide, direct tunneling occurs with a film thickness of 3 nm or less. Therefore, even if the intermediate film 7 is formed of an insulating material, the first metal film 4 and the second metal film 5 are electrically connected.

  The second electrodes (4, 5a to 5d) further include intermediate films and third to fifth metal films (5b to 5d) alternately stacked on the second metal film 5a. That is, the second electrode (4, 5a to 5d) has a multilayer structure in which the intermediate film 7 is inserted between the first to fifth metal films (4, 5a to 5d).

  The manufacturing method of the second electrode (4, 5a to 5d) is as follows. As the first metal film 4, for example, an Al film is formed by a vacuum deposition method, patterned into a predetermined shape together with the organic EL film 3, and then intermediated by sputtering Al with oxygen introduced into the sputtering apparatus. An ultrathin aluminum oxide film is formed as the film 7. Then, the second metal film 5a is formed by stopping the introduction of oxygen into the sputtering apparatus and sputtering Al. Thereafter, an aluminum oxide film (intermediate film 7) is formed again by sputtering Al with oxygen introduced into the sputtering apparatus. By repeating ON / OFF of oxygen introduction into the sputtering apparatus, the third metal film 5b to the fifth metal film 5d are sequentially formed while the intermediate film 7 is inserted therebetween. Finally, the second metal film 5a to the fifth metal film 5d are simultaneously patterned into a predetermined shape. In this way, the second electrodes (4, 5a to 5d) can be formed. Other manufacturing procedures are the same as those in the first embodiment.

  As described above, according to the third embodiment of the present invention, since the intermediate film 7 is sandwiched between the first metal film 4 and the second metal film 5a, the intermediate film 7 is straddled. The crystal grain boundaries of the metal film do not continue, and the crystal grain boundaries do not penetrate the front and back surfaces of the second electrode (4, 5a). Therefore, water molecules and oxygen molecules in the air are difficult to reach the organic EL film 3 through the second electrodes (4, 5a) through the crystal grain boundaries. As described above, the organic EL film 3 is hardly deteriorated by covering the organic EL film with the second electrodes (4, 5a) having high gas barrier properties and sealing properties. In addition, since the organic EL film 3 is sealed by the second electrode (4, 5a), the heat dissipation is higher than the conventional example in which the metal electrode is sealed by the inorganic insulating film or the laminated film of the inorganic film and the organic film. Increases, reduces electrical resistance and improves durability.

  The second electrode (4, 5a to 5d) further includes the intermediate film 7 and the third to fifth metal films (5b to 5d) alternately stacked on the second metal film 5a, thereby The gas barrier properties and sealing properties of the second electrode (4, 5a to 5d) are further improved.

  As described above, the present invention has been described with reference to three embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  In the embodiment of the present invention, the case where the first electrode 2 is an anode and the second electrode (4, 5) is a cathode has been described. However, the first electrode 2 is a cathode and the second electrode 2 is a cathode. The present invention can also be applied to the case where the electrodes (4, 5) are anodes.

  In the embodiment of the present invention, the organic EL film 3 is patterned together with the first metal film 4. However, the organic EL film 3 may be formed in a state patterned in advance by a printing method.

It is sectional drawing which shows the structure of the organic electroluminescent light emitting element concerning the 1st and 2nd embodiment of this invention. It is sectional drawing which shows the structure of the organic electroluminescent light emitting element concerning the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... 1st electrode 3 ... Organic EL film 4 ... 1st metal film 5 ... 2nd metal film 5a ... 2nd metal film 5b ... 3rd metal film 5c ... 4th metal film 5d ... Fifth metal film 6 ... Insulating film 7 ... Intermediate film

Claims (5)

A substrate,
A first electrode formed on the main surface of the substrate;
An organic EL film formed on the first electrode;
A second electrode formed so as to cover the surface of the organic EL film,
The second electrode is
A first metal film formed on the organic EL film;
An amorphous second metal film formed on the first metal film;
An organic EL light emitting device comprising:   The organic EL light emitting device according to claim 1, wherein the amorphous second metal film is made of a metal compound containing at least one of oxygen and nitrogen.   The organic EL light-emitting element according to claim 2, wherein the amorphous second metal film is made of an aluminum compound containing oxygen. A substrate,
A first electrode formed on the main surface of the substrate;
An organic EL film formed on the first electrode;
A second electrode made of metal formed so as to cover the surface of the organic EL film,
The second electrode is
A first metal film formed on the organic EL film;
A microcrystalline second metal film formed on the first metal film;
An organic EL light emitting device comprising:   The organic EL light-emitting element according to claim 4, wherein the microcrystalline second metal film is made of an alloy of two or more metals.

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