JP5861961B2 - Organic EL device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an organic EL element and a method for manufacturing the same, and more particularly to a laminated structure from an anode (anode) to an organic light emitting layer.

2. Description of the Related Art In recent years, organic EL (Electro Luminescence) elements that have been researched and developed are light-emitting elements that utilize the electroluminescence phenomenon of solid fluorescent materials. The configuration of the organic EL element according to the prior art will be described with reference to FIG.
As shown in FIG. 12, in the organic EL element according to the prior art, an anode 905 is formed on a TFT substrate 903 composed of a substrate 901 and a TFT 902 with an interlayer insulating film 904 interposed therebetween. In the case of a top emission type in which light is extracted upward in the Z-axis direction, the anode 905 is made of a light reflective metal (for example, Ag or Al, or an alloy containing them). When an organic EL panel is assumed, the anode 905 is configured in units of subpixels.

The anode 905 is connected to the drain 902a of the TFT 902 through a contact hole opened in the interlayer insulating film 904 and the passivation film 902b of the TFT 902.
The anode 905 is covered with a cap layer (transparent conductive layer) 915 made of, for example, ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). The cap layer 915 is provided so as not to reduce the light reflectivity of the anode 905. A bank 908 defining sub-pixels is provided between the adjacent anodes 905 on the interlayer insulating film 904, and a hole injection layer 907 and a hole transport are formed in a recess formed by the bank 908. A layer 909 and an organic light emitting layer 910 are sequentially stacked. On the organic light emitting layer 910, an electron transport layer 911, a cathode 912, and a sealing layer 913 are sequentially stacked.

In the organic EL element, a functional layer 914 is configured by a hole injection layer 907, a hole transport layer 909, an organic light emitting layer 910, and an electron transport layer 911.
Conventionally, a conductive polymer such as PEDOT / PSS (a mixture of polythiophene and polystyrene sulfonic acid) has been used as a constituent material of the hole injection layer 907, but recently, transition metals (for example, Research and development using an oxide layer of tungsten or the like has also been made (see, for example, Patent Document 1).

JP 2009-277788 A

The organic EL element is required to further improve the light extraction efficiency, and from the viewpoint of the degree of freedom in designing the cavity, it is required to omit the cap layer 915 that is a limiting factor.
However, when the cap layer 915 made of ITO, which is an oxide, is simply to be omitted, the hole injection amount from the anode 905 to the organic light emitting layer 910 is equal to the electron injection amount from the cathode 912 to the organic light emitting layer 910. On the other hand, it becomes excessive, and the carrier balance is lost. If the carrier balance is lost in this manner, the current that does not contribute to light emission increases, and it is considered that the light emission efficiency and the lifetime are reduced.

  The present invention has been made to solve the above-described problems, and can obtain a high degree of freedom in cavity design, and suppresses the collapse of carrier balance. An object of the present invention is to provide an organic EL element capable of extending the lifetime and a method for manufacturing the same.

The organic EL element according to one embodiment of the present invention is characterized by adopting the following configuration.
The organic EL device according to one embodiment of the present invention includes at least an anode, a first metal oxide layer, a second metal oxide layer, a light emitting layer, and a cathode.
Anode (anode); containing metal M _A of aluminum (Al) or silver (Ag), or alloys thereof.

A first metal oxide layer; including a first oxide M _B Ox which is formed above the anode and is an oxide of metal M _{B made} of tungsten (W), molybdenum (Mo) or nickel (Ni). The composition ratio x of oxygen in the first oxide M _B Ox in at least part of the inside is smaller than the stoichiometric ratio.
· Second metal oxide layer; between the anode and the first metal oxide layer is formed in contact with both the anode and the first metal oxide layer, the second oxide is an oxide of the same metal as the metal M _A object M _a comprises Oy, second oxide M _a composition ratio y of oxygen in Oy at least a portion of the layer in less than the stoichiometric ratio.

-Light-emitting layer; provided above the first metal oxide layer and containing an organic light-emitting material.
-Cathode (cathode); provided above the light emitting layer.

In the organic EL device according to one aspect of the present invention, the second metal oxide layer is interposed between the anode and the first metal oxide layer so as to be in contact with both. This second metal oxide layer is a layer containing a second oxide M _A Oy which is an oxide of the same metal as the metal M _A, and the first metal oxide layer (hole injection) is formed on the metal layer for forming the anode. (Corresponding to the layer) is a layer formed at the interface portion. Therefore, in the organic EL element according to the present invention, a cap layer is not provided on the anode, and the degree of freedom in cavity design is high.

In the organic EL device according to one embodiment of the present invention, the composition ratio y of oxygen in the second oxide M _A Oy included in the second metal oxide layer is at least partly higher than the stoichiometric ratio in the layer. Since it is small, the insulating property is relaxed despite being an oxide (having hole injection property), and the second metal oxide layer is interposed between the anode and the first metal oxide layer, The amount of holes injected from the anode into the first metal oxide layer (corresponding to the hole injection layer) is limited, and it is possible to balance the injection of holes and electrons. Therefore, the organic EL element according to one embodiment of the present invention has high luminous efficiency and a long lifetime.

  As described above, in the organic EL element according to one embodiment of the present invention, high degree of freedom in cavity design can be obtained, and the loss of carrier balance is suppressed, so that the light emission efficiency is high and the lifetime is long. It is.

1 is a schematic block diagram showing a configuration of an organic EL display device 1 according to Embodiment 1 of the present invention. (A) is a schematic cross section which shows the partial structure of the display panel 10 in the organic electroluminescence display 1, (b) is a schematic cross section which expands and shows the part. 3 is a schematic plan view illustrating a configuration of subpixels 100a, 100b, and 100c in the display panel 10. FIG. 3 is a schematic cross-sectional view showing a configuration of a mixed layer 106 included in the configuration of the display panel 10. FIG. (A) is a schematic diagram showing the concentration distribution of aluminum (Al) in the mixed layer 106, and (b) is a schematic diagram showing the concentration distribution of tungsten (W) in the mixed layer 106. It is a schematic diagram which shows the manufacturing process of the organic electroluminescence display 1 which concerns on Embodiment 1 of this invention. (A)-(c) is a schematic process drawing which shows a part process of the manufacturing process of the display panel 10. FIG. (A)-(c) is a schematic process drawing which shows a part process of the manufacturing process of the display panel 10. FIG. It is a schematic diagram which compares the lifetime of the organic electroluminescence display 1 which concerns on embodiment of this invention, and the lifetime of the organic electroluminescence display which concerns on a comparative example. It is a table | surface which shows the film-forming conditions which concern on manufacture of a hole injection layer among the manufacturing processes of the organic electroluminescence display which concerns on Embodiment 2 of this invention. It is a schematic plan view which shows the bank structure as a modification. It is a schematic cross section which shows the structure of the organic electroluminescence display panel which concerns on a prior art.

[Outline of Embodiments of the Present Invention]
The organic EL device according to one embodiment of the present invention includes at least an anode, a first metal oxide layer, a second metal oxide layer, a light emitting layer, and a cathode.
Anode (anode); containing metal M _A of aluminum (Al) or silver (Ag), or alloys thereof.

A first metal oxide layer; including a first oxide M _B Ox which is formed above the anode and is an oxide of metal M _{B made} of tungsten (W), molybdenum (Mo) or nickel (Ni). The composition ratio x of oxygen in the first oxide M _B Ox in at least part of the inside is smaller than the stoichiometric ratio.
· Second metal oxide layer; between the anode and the first metal oxide layer is formed in contact with both the anode and the first metal oxide layer, the second oxide is an oxide of the same metal as the metal M _A object M _a comprises Oy, second oxide M _a composition ratio y of oxygen in Oy at least a portion of the layer in less than the stoichiometric ratio.

-Light-emitting layer; provided above the first metal oxide layer and containing an organic light-emitting material.
-Cathode (cathode); provided above the light emitting layer.
In the organic EL device according to one aspect of the present invention, the second metal oxide layer is interposed between the anode and the first metal oxide layer so as to be in contact with both. This second metal oxide layer is a layer containing a second oxide M _A Oy which is an oxide of the same metal as the metal M _A, and the first metal oxide layer (hole injection) is formed on the metal layer for forming the anode. (Corresponding to the layer) is a layer formed at the interface portion. Therefore, in the organic EL element according to the present invention, a cap layer is not provided on the anode, and the degree of freedom in cavity design is high.

In the organic EL device according to one embodiment of the present invention, the oxygen composition ratio y in the second oxide M _A Oy included in the first metal oxide layer is at least partly higher than the stoichiometric ratio in the layer. Since it is small, it has hole injection properties despite being an oxide, and the amount of holes injected from the anode to the first metal oxide layer (corresponding to the hole injection layer) is limited by the insertion of the second metal oxide layer. This makes it possible to balance the injection of holes and electrons. Therefore, the organic EL element according to one embodiment of the present invention has high luminous efficiency and a long lifetime.

As described above, in the organic EL element according to one embodiment of the present invention, high degree of freedom in cavity design can be obtained, and the loss of carrier balance is suppressed, so that the light emission efficiency is high and the lifetime is long. It is.
The organic EL device according to an embodiment of the present invention, the second metal oxide layer, a metal M _B the same metals or oxides thereof, are also included, may also be characterized in that.

Thus, the second metal oxide layer, a metal M _B and the same metal contained in the first metal oxide layer, or have a configuration that also includes the oxides, the second metal oxide layer, the anode When forming a 1st metal oxide layer on the metal layer (anode preparation layer) concerning formation, it shows that it is a layer formed in the interface part. Further, as described above, in the first metal oxide layer comprises a first oxide M _B Ox, first oxide M _B oxygen composition ratio x in Ox at least partially stoichiometry in the layer Smaller than the ratio. Therefore, in the formation process, oxygen is drawn from the preparation layer of the second metal oxide layer formed at the interface with respect to the preparation layer of the first metal oxide layer containing the first oxide M _B Ox in the oxygen deficient state. Is.

From the above, even if the anode is not covered with a cap layer made of ITO or the like, the injection balance of holes and electrons into the light emitting layer can be achieved, and the light emitting efficiency is high and the life is long.
Gradient organic EL device according to an embodiment of the present invention, the same metal as the metal M _A in the second metal oxide layer is from the side in contact with the anode toward the side in contact with the first metal oxide layer, its concentration is gradually reduced It can also be characterized by being included.

The organic EL element which concerns on 1 aspect of this invention can also be characterized by the layer thickness of a 2nd metal oxide layer being less than 10 [nm]. Here, if the thickness of the second metal oxide layer made of oxide is set to 10 [nm] or more, there will be a problem from the viewpoint of hole injection due to its insulating properties.
On the other hand, as described above, by defining the thickness of the second metal oxide layer as less than 10 [nm], it is possible to ensure hole injectability as a light emitting element.

The organic EL element according to one embodiment of the present invention may be characterized in that the thickness of the second metal oxide layer is 3 [nm] or more and 7 [nm] or less.
Moreover, the organic EL element which concerns on 1 aspect of this invention can also be characterized by the layer thickness of a 2nd metal oxide layer being 4 [nm] or more and 5 [nm] or less.
The organic EL device according to an embodiment of the present invention, the metal M _A is aluminum (Al), a metal M _B is tungsten (W), it may also be characterized in that.

By adopting aluminum (Al) as a constituent material of the anode, it is possible to achieve both a reduction in material cost and high light reflection characteristics, and a low manufacturing cost and high luminous efficiency.
In the organic EL device according to one embodiment of the present invention, the composition ratio x of oxygen in the first oxide M _B Ox in at least a part of the first metal oxide layer is smaller than the stoichiometric ratio ( x <3). Specifically, the first metal oxide layer is made of WOx, and the oxygen composition ratio is (x <3). By adopting such a configuration, the hole injection property of the layer made of metal oxide can be ensured. Therefore, the organic EL element according to one embodiment of the present invention has high light emission efficiency.

In the organic EL device according to one embodiment of the present invention, the composition ratio y of oxygen in the second oxide M _A Oy in at least a part of the second metal oxide layer is smaller than the stoichiometric ratio ( y <3/2). Specifically, the second metal oxide layer is made of AlOy, and the oxygen composition ratio is (y <3/2). By adopting such a configuration, it is possible to limit the amount of holes injected while ensuring the hole injection property of the layer made of metal oxide, and to balance the injection of holes and electrons into the light emitting layer. . Therefore, the organic EL element according to one embodiment of the present invention has high luminous efficiency and a long lifetime.

The organic EL element according to one embodiment of the present invention may be characterized in that the composition ratio y is 0.42 or less.
The organic EL element according to one embodiment of the present invention can be characterized in that both the first metal oxide layer and the second metal oxide layer have conductivity.
The organic EL device according to an embodiment of the present invention, the second metal oxide layer, using a thin film deposition method of introducing oxygen at least some period, on the layer containing the metal M _A, oxidation of the metal M _B When the first oxide M _B Ox, which is a material, is to be formed, the first oxide M _B Ox may be a layer formed at an interface portion between both layers.

Moreover, the manufacturing method of the organic EL element which concerns on 1 aspect of this invention performs the following manufacturing processes, It is characterized by the above-mentioned.
( _A ) An anode (anode) preparation layer containing metal MA made of aluminum (Al), silver (Ag), or an alloy thereof is formed.
(B) to the anode (anode) Preparation layer, using a thin film deposition method of introducing oxygen at least some period, oxides of metal M _B consisting of tungsten (W) or molybdenum (Mo) or nickel (Ni) A first metal oxide layer containing the first oxide M _B Ox is formed.

(C) A light emitting layer containing an organic light emitting material is formed above the first metal oxide layer.
(D) A cathode (cathode) is provided above the light emitting layer.
(B) During formation of the first metal oxide layer, the interface between the anode (anode) preparation layer and the first metal oxide layer is in contact with both the anode (anode) preparation layer and the first metal oxide layer. And the second oxide M _A Oy which is an oxide of the metal M _A , and the composition ratio y of oxygen in the second oxide M _A Oy in at least a part of the layer is smaller than the stoichiometric ratio. A second metal oxide layer is formed.

(B) After the formation of the first metal oxide layer, the portion obtained by removing the second metal oxide layer from the anode (anode) preparation layer becomes the anode (anode). In the first metal oxide layer, The composition ratio x of oxygen in at least a part is smaller than the stoichiometric ratio.
In the method of manufacturing an organic EL element according to one aspect of the present invention, the second metal contact layer is in contact with both the anode and the first metal oxide layer during the formation of the (b) first metal oxide layer. A metal oxide layer will be inserted. Then, the second metal oxide layer becomes a layer containing the second oxide M _A Oy which is the same metal oxide as the metal M _A after the formation of the (b) first metal oxide layer. Therefore, in the organic EL element according to the present invention, a cap layer is not provided on the anode, and the degree of freedom in cavity design is high.

In the method for manufacturing an organic EL element according to one embodiment of the present invention, the oxygen composition ratio y in the second oxide M _A Oy included in the formed first metal oxide layer is at least part of the layer. Since it is smaller than the stoichiometric ratio, it has a hole injection property despite being an oxide, and from the anode to the first metal oxide layer (corresponding to the hole injection layer) by interposing the second metal oxide layer. The amount of holes to be injected is limited, and the device has a balanced injection of holes and electrons. Therefore, in the method for manufacturing an organic EL element according to one embodiment of the present invention, an organic EL element having high emission efficiency and a long lifetime can be manufactured.

As described above, if the method for manufacturing an organic EL element according to one embodiment of the present invention is used, a high degree of freedom in cavity design can be obtained, and high luminous efficiency can be achieved by suppressing the collapse of carrier balance. In addition, a long-life organic EL element can be obtained.
The organic EL device manufacturing method according to one aspect of the present invention is characterized in that in the formation of the first metal oxide layer (b), a mixed gas of an inert gas and oxygen is introduced over the entire period. You can also

  In addition, in the method for manufacturing an organic EL element according to one embodiment of the present invention, in the formation of the first metal oxide layer (b), only an inert gas is introduced in the first half of the period, and the inert gas and oxygen are introduced in the second half of the period. It is also possible to introduce a mixed gas of As described above, if only the inert gas is introduced in the first period of the film formation period of the first metal oxide layer and then the mixed gas of the inert gas and oxygen is introduced in the latter period, the first metal oxide layer is inactivated over the entire period. Compared with the case where a mixed gas of active gas and oxygen is introduced, the thickness of the second metal oxide layer can be controlled to be thin. Therefore, it is excellent from the viewpoint of relaxing the electrical insulation of the second metal oxide layer made of metal oxide.

The manufacturing method of the organic EL element which concerns on 1 aspect of this invention can also perform heat processing after formation of the said (b) 1st metal oxide layer, It can also be characterized by the above-mentioned. By performing the heat treatment in this manner, oxygen is thermally diffused from the layer made of the second oxide M _A Oy to the first metal oxide layer in the oxygen deficient state, and the electrical insulation of the second metal oxide layer is further relaxed. Is done.
The method of manufacturing an organic EL device according to an embodiment of the present invention, specifically, an aluminum (Al) used as the metal M _A, using tungsten (W) as the metal M _B, may also be characterized in that.

The manufacturing method of the organic EL element which concerns on 1 aspect of this invention can also be characterized by making layer thickness of a 2nd metal oxide layer into less than 10 [nm]. As described above, the effect of this is to make the electrical insulation property at a level that does not cause a problem in practice.
Below, the characteristic of an aspect which concerns on this invention, an effect | action and an effect is demonstrated using a specific example. The present invention is not limited to the following embodiments except for essential characteristic components.

[Embodiment 1]
1. Configuration of Organic EL Display Device 1 The configuration of the organic EL display device 1 according to Embodiment 1 of the present invention will be described with reference to FIG.
As shown in FIG. 1, the organic EL display device 1 includes a display panel (organic EL display panel) 10 and a drive control circuit unit 20 connected thereto.

The display panel 10 is a panel using an electroluminescent phenomenon of an organic material, and a plurality of organic EL elements are arranged and configured in a matrix, for example. The drive control circuit unit 20 includes four drive circuits 21 to 24 and a control circuit 25.
In the organic EL display device 1 according to the present embodiment, the arrangement of the drive control circuit unit 20 with respect to the organic EL display panel 10 is not limited to this.

2. Configuration of Display Panel 10 The configuration of the display panel 10 of the organic EL display device 1 will be described with reference to FIGS.
First, as shown in FIG. 2A, the display panel 10 is formed using a substrate 101 as a base. A TFT (thin film transistor) 102 is formed on the substrate 101, and the TFT substrate 103 is configured by a combination of the substrate 101 and the TFT 102.

The TFT 102 includes an electrode including a drain 102a, a semiconductor layer (not shown), a passivation film 102b, and the like.
An interlayer insulating film 104 is laminated on the TFT substrate 103, and contact holes are formed corresponding to the drains 102 a in the TFT 102. The contact hole also communicates with the passivation film 102 b, and the drain 102 a is exposed at the bottom of the interlayer insulating film 104.

On the interlayer insulating film 104, an anode 105 is formed for each subpixel. The anode 105 is connected to the drain 102a of the TFT 102 which is also formed along the inner wall of the contact hole and is exposed at the bottom. On the anode 105, a hole injection layer 107 which is a metal oxide layer is formed.
As shown in FIG. 2A, a bank 108 is erected in part on the hole injection layer 107. As shown in FIG. 3, in the display device 10 according to the present embodiment, the bank 108 includes a plurality of elements 108a extending in the X-axis direction and a plurality of elements 108b extending in the Y-axis direction. Each part surrounded by these becomes subpixels 100a, 100b, and 100c, and one pixel is formed by combining three subpixels 100a, 100b, and 100c adjacent in the Y-axis direction. Is configured.

  Returning to FIG. 2A, a hole transport (IL) layer 109 and an organic light emitting layer 110 are sequentially stacked in each recess surrounded by the bank 108. Then, an electron transport layer 111, a cathode 112, and a sealing layer 113 are sequentially stacked so as to cover the organic light emitting layer 110 and the bank 108. As illustrated in FIG. 2A, the stacked body of the hole injection layer 107, the hole transport layer 109, the organic light emitting layer 110, and the electron transport layer 112 is a functional layer in the display panel 10.

In addition, the material used for formation of each component can be made into the following, for example.
(I) Substrate 101
The substrate 101 is, for example, alkali-free glass, soda glass, non-fluorescent glass, phosphate glass, boric acid glass, quartz, acrylic resin, styrene resin, polycarbonate resin, epoxy resin, polyethylene, polyester, silicone resin. Or an insulating material such as alumina.

(Ii) Interlayer insulating film 104
The interlayer insulating film 104 is formed using, for example, an organic compound such as polyimide, polyamide, or acrylic resin material.
(Iii) Anode 105
The anode 105 is made of aluminum (Al) or silver (Ag) or an alloy containing them. In the case of the display panel 10 according to this embodiment of the top emission type, it is preferable that the surface portion has high light reflectivity. In the present embodiment, as an example, the anode 105 is formed using an alloy of aluminum (Al).

(Iv) Hole injection layer 107
The hole injection layer 107 is a layer made of an oxide of tungsten (W), molybdenum (Mo), or nickel (Ni). As described above, in the display panel 10 according to the present embodiment that employs the hole injection layer 107 made of a metal oxide, the organic light emitting layer 110 is formed by stably generating holes or assisting the generation of holes. Has a function of injecting holes, and has a large work function.

  Here, as described above, in the case of the present embodiment in which the hole injection layer 107 is formed of an oxide of a transition metal, a plurality of levels can be obtained by taking a plurality of oxidation numbers. As a result, hole injection becomes easy and the driving voltage can be reduced. In particular, it is desirable to use tungsten oxide (WOx) from the viewpoint of stably injecting holes and assisting the generation of holes.

Here, in this embodiment, as an example, a hole injection layer is formed from an oxide WOx of tungsten (W), and at least a part of the layer has a chemical composition ratio of oxygen in the oxide WOx. Smaller than the theoretical ratio (x <3). That is, the hole injection layer 107 is at least partially composed of the oxygen-deficient oxide WOx.
(V) Bank 108
The bank 108 is formed using an organic material such as a resin and has an insulating property. Examples of the organic material used for forming the bank 108 include acrylic resin, polyimide resin, and novolac type phenol resin. The bank 106 preferably has organic solvent resistance. Furthermore, since the bank 108 may be subjected to an etching process, a baking process, or the like during the manufacturing process, the bank 108 should be formed of a highly resistant material that does not excessively deform or alter the process. Is preferred. In addition, the surface can be treated with fluorine to give water repellency.

When the bank 108 is formed using a lyophilic material, the difference in lyophilicity / liquid repellency between the surface of the bank 108 and the surface of the organic light emitting layer 110 is reduced, and the organic light emitting layer 110 is formed. This is because it becomes difficult to selectively hold the ink containing the organic substance in the recess formed by the surrounding of the bank 108.
Furthermore, as for the structure of the bank 108, not only a single layer structure as shown in FIG. 2A but also a multilayer structure of two or more layers can be adopted. In this case, the above materials can be combined for each layer, and an inorganic material and an organic material can be used for each layer.

(Vi) Hole transport layer 109
The hole transport layer 109 is formed using a polymer compound having no hydrophilic group. For example, polyfluorene or a derivative thereof, or a polymer compound such as polyarylamine or a derivative thereof that does not have a hydrophilic group can be used.
(Vii) Organic light emitting layer 110
As described above, the organic light emitting layer 110 has a function of emitting light by generating an excited state by injecting and recombining holes and electrons. As a material used for forming the organic light emitting layer 110, it is necessary to use a light emitting organic material that can be formed by a wet printing method.

  Specifically, for example, an oxinoid compound, a perylene compound, a coumarin compound, an azacoumarin compound, an oxazole compound, an oxadiazole compound, a perinone compound, and pyrrolopyrrole described in Japanese Patent Publication (JP-A-5-163488). Compound, naphthalene compound, anthracene compound, fluorene compound, fluoranthene compound, tetracene compound, pyrene compound, coronene compound, quinolone compound and azaquinolone compound, pyrazoline derivative and pyrazolone derivative, rhodamine compound, chrysene compound, phenanthrene compound, cyclopentadiene compound, stilbene compound , Diphenylquinone compound, styryl compound, butadiene compound, dicyanomethylenepyran compound, dicyanomethylenethiopyran compound, fluorene In compounds, pyrylium compounds, thiapyrylium compounds, serenapyrylium compounds, telluropyrylium compounds, aromatic ardadiene compounds, oligophenylene compounds, thioxanthene compounds, anthracene compounds, cyanine compounds, acridine compounds, 8-hydroxyquinoline compound metal complexes, 2- It is preferably formed of a fluorescent substance such as a metal complex of a bipyridine compound, a Schiff salt and a group III metal complex, an oxine metal complex, or a rare earth complex.

(Viii) Electron transport layer 111
The electron transport layer 111 has a function of transporting electrons injected from the cathode 112 to the organic light emitting layer 110, and includes, for example, an oxadiazole derivative (OXD), a triazole derivative (TAZ), a phenanthroline derivative (BCP, Bphen). ) Or the like.
Note that a layer formed using a dry process such as a vapor deposition method using an alkali metal such as barium (Ba) as the electron transporting layer 111 may be employed.

(Ix) Cathode 112
The cathode 112 is formed using, for example, ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). In the case of the top emission type display panel 10 as in the present embodiment, it is preferably formed of a light transmissive material. About light transmittance, it is preferable that the transmittance | permeability shall be 80 [%] or more.

(X) Sealing layer 113
The sealing layer 113 has a function of suppressing exposure of an organic layer such as the organic light emitting layer 110 to moisture or air. For example, SiN (silicon nitride), SiON (silicon oxynitride) It is formed using materials such as. Further, a sealing resin layer made of a resin material such as an acrylic resin or a silicone resin may be provided on a layer formed using a material such as SiN (silicon nitride) or SiON (silicon oxynitride).

In the case of the display panel 10 according to the present embodiment that is a top emission type, the sealing layer 113 is preferably formed of a light transmissive material.
3. Configuration Between Cathode 105 and Hole Injection Layer 107 The configuration between cathode 105 and hole injection layer 107 will be described with reference to FIGS. 2B, 4 and 5. FIG. FIG. 2B is a schematic cross-sectional view enlarging a part (part A) in FIG.

  As shown in FIG. 2B, in the display panel 10, the mixed layer 106 is interposed between the anode 105 and the hole injection layer 107 so as to be in contact with both the anode 105 and the hole injection layer 107. . As shown in FIG. 4, the mixed layer 106 is a layer in which aluminum (Al), which is a component of the anode 105, tungsten (W), which is a component of the hole injection layer 107, and oxygen (O) are mixed. is there.

Returning to FIG. 2B, the thickness t ₁₀₆ of the mixed layer 106 is defined to be less than 10 [nm]. This is because when the thickness t ₁₀₆ of the mixing layer 106 is a metal oxide layer is 10 [nm] or more, the electric resistance is increased problem. Therefore, the thickness that can be adopted as an actual device is less than 10 [nm].
The thickness t ₁₀₆ of the mixed layer 106 may be less than 10 [nm] for the reasons described above. For example, the thickness t ₁₀₆ is in the range of 3 [nm] to 7 [nm], preferably 4 [nm] to 5 [nm]. It is within the range of [nm].

As shown in FIG. 5A, in the mixed layer 106, the aluminum (Al) in the layer is not uniformly distributed, but the concentration on the side in contact with the anode 105 is high, and the hole injection layer 107 It has a concentration gradient that gradually decreases toward the side in contact with.
Conversely, as shown in FIG. 5B, the concentration of tungsten (W) in the mixed layer 106 is high on the side in contact with the hole injection layer 107 and gradually decreases toward the side in contact with the anode 105. Have.

As for aluminum oxide (AlOy) in the mixed layer 106, the composition ratio y of oxygen (O) in at least a part of the layer is smaller than the stoichiometric ratio (y <3/2). That is, in the display panel 10 according to the present embodiment, the insulating property of the mixed layer 106 is relaxed as compared with Al ₂ O ₃ .
In addition, the composition ratio y of oxygen (O) in at least a part of the layer of aluminum oxide (AlOx) in the present embodiment is, for example, 0.42.

4). Manufacturing Method (i) Overview of Manufacturing Method of Organic EL Display Device 1 An overview of a manufacturing method of the organic EL display device 1 according to the present embodiment will be described with reference to FIG.
As shown in FIG. 6, first, a TFT substrate 103 is prepared (step S1), and an interlayer insulating film 104 is stacked on the layer (step S2). As described above, the contact hole is formed at each position on the drain 102a of the TFT 102 in the interlayer insulating film 104, and then the anode 105 is formed.

The anode 105 is formed, for example, by forming a metal film (Al alloy film) using a sputtering method, a vacuum deposition method, or the like, and then partitioning into sub-pixel units by etching.
Next, a hole injection layer 107 made of a metal oxide layer (for example, WOx) is formed on the anode 105 (step S4). For forming the hole injection layer 107, for example, a sputtering method is used. Specifically, a mixed gas of argon (Ar) and oxygen (O) as an inert gas is introduced into the chamber of the sputtering apparatus with a gas pressure of 4 [Pa] to 7 [Pa], and 0 The film is formed with a power of 7 [kW] to 1.5 [kW]. For the mixed gas introduced into the chamber, the partial pressure ratio of oxygen with respect to the total pressure is 50 [%].

  Note that the hole injection layer 107 in this embodiment includes tungsten (W) as described above, and is 1.8 [eV] to 3.6 [eV] lower than the lowest binding energy in the valence band. It has an occupied level in the binding energy region. In the hole injection layer 107, the ultraviolet photoelectron spectroscopic analysis (UPS) spectrum raised in a binding energy region 1.8 [eV] to 3.6 [eV] lower than the lowest binding energy. And a raised shape in an X-ray photoelectron spectroscopy (XPS) spectrum in a binding energy region that is 1.8 [eV] to 3.6 [eV] lower than the lowest binding energy in the valence band. Have

Here, by forming the hole injection layer 107, as shown in FIG. 2B, the mixed layer 106 is formed at the interface between the anode 105 and the hole injection layer 107. This will be described later. .
In addition to the above, the following method can also be adopted for forming the anode 105 and the hole injection layer 107.

First, a film made of a metal (for example, an Al alloy) is formed, and then a film made of a metal oxide (for example, WO _x ) is formed.
Next, the metal film and the metal oxide film are heat-treated (for example, baked at a temperature of 230 [° C.] or higher), and then divided into sub-pixel units by etching, whereby the anode 105 and the hole injection layer 107 are formed. can do.

Next, the bank 108 is formed on the hole injection layer 107 (step S5). The bank 108 is formed by first laminating a bank material layer using a material containing a photosensitive resin component and a fluorine component by a spin coat method or the like, and then performing mask exposure and development processing to form a bank material. This is done by patterning the layer.
In forming the bank 108, for example, exposure is performed at all wavelengths, and paddle development or spray development is performed using a TMAH developer. Thereafter, a rinsing process using pure water is performed. Then, the bank 108 can be formed by baking. As an example of the formation conditions of the bank 108, the size of the subpixel is 300 [μm] in the long side direction and 100 [μm] in the short side direction, and the bank depends on the size of the subpixel to be formed. The formation conditions of 108 need to be changed as appropriate.

Next, the hole transport layer 109 and the organic light emitting layer 110 are sequentially stacked in each recess formed by the surrounding of the bank 108 (steps S6 and S7). Each of the hole transport layer 109 and the organic light emitting layer 110 is formed by, for example, forming a film using a printing method and then baking it.
Next, the electron transport layer 111, the cathode 112, and the sealing layer 113 are sequentially stacked on the organic light emitting layer 110 and the exposed surface of the bank 108 (steps S8, S9, and S10). Then, after bonding the CF substrate on which the color filter layer is formed (step S11), the drive control unit 20 is connected (step S12).

  Finally, an aging process is performed on the organic EL display device 1 (step S13). The aging process is performed, for example, by performing an energization process until the hole mobility becomes 1/10 or less with respect to the hole injection property before the process. More specifically, 0 [min.] Is set so that the luminance is equal to or higher than the luminance at the time of actual use of the apparatus and is three times or less. ] Over 30 [min. ], The aging is performed by executing the energization process.

The organic EL display device 1 is completed as described above.
(2) Formation of Mixed Layer 106 Next, formation of the mixed layer 106 at the interface portion between the anode 105 and the hole injection layer 107 will be described with reference to FIGS.
First, as shown in FIG. 7A, an interlayer insulating film 104 is formed on the TFT substrate 103. This is as described above. Note that illustration of contact holes and the like in the TFT 102 and the interlayer insulating film 104 is omitted.

Next, as shown in FIG. 7B, an anode preparation layer 1050 made of an aluminum (Al) alloy is formed on the interlayer insulating film 104. As described above, the anode preparation layer 1050 is thereafter patterned by etching.
Next, after patterning the anode preparation layer 1050, the workpiece is put into a chamber of a sputtering apparatus, and a mixed gas of argon (Ar) and oxygen (O) is introduced, and an oxide of tungsten (W) (WOx And a hole injection preparation layer 1070 is formed. Immediately after starting the introduction of the mixed gas, a metal oxide layer 1060 of aluminum (Al) is formed on the upper surface portion of the anode preparation layer 1050 in the Z-axis direction, as shown in FIG. The metal oxide layer 1060 in this state is considered to be in a state where the oxygen composition ratio is the same as or substantially the same as the stoichiometric ratio. That is, when the metal oxide layer 1060 is AlOy, the oxygen composition ratio y is considered to be approximately 3/2.

The upper surface portion of the anode preparation layer 1050 becomes the metal oxide layer 1060, so that the remaining portion becomes the anode 105 (see FIG. 7C).
As shown in FIG. 8A, when the film formation of the hole injection preparation layer 1070 by the sputtering method proceeds, oxygen (O) in the metal oxide layer 1061 is drawn into the hole injection preparation layer 1071 in the oxygen deficient state. On the contrary, it is considered that tungsten (W) is injected from the hole injection preparation layer 1071 into the metal oxide layer 1061 (see FIG. 8B).

Finally, by applying heat treatment, oxygen (O) is further diffused (thermally diffused) into the hole-injection preparation layer 1071 in an oxygen-deficient state, and the insulating property of the metal oxide layer 1061 is relaxed.
Through the above process, as shown in FIG. 8C, the anode 105 and the hole injection layer 107, and the mixed layer 106 interposed therebetween and in contact with both the anode 105 and the hole injection layer 107 are formed. It is formed. Therefore, in the mixed layer 106, aluminum (Al), oxygen (O), and tungsten (W) are mixed (see FIG. 4). The oxygen composition ratio y in AlOy is smaller than the stoichiometric ratio (y <3/2), for example, “0.42”.

The formed hole injection layer 107 is made of an oxide (WOx) of tungsten (W), and the oxygen composition ratio x in at least a part of the layer is smaller than the stoichiometric ratio ( x <3).
5. Effect In the display panel 10 according to the embodiment of the present invention, the mixed layer 106 which is a metal oxide layer is interposed between the anode 105 and the hole injection layer 107 so as to be in contact with both. The mixed layer 106 is composed of aluminum (Al), which is a constituent metal of the anode 105, tungsten (W), which is a constituent metal of the hole injection layer 107, and oxygen (O) taken in during sputtering. ing. As described above, the mixed layer 106 is a layer formed at the interface when the hole injection layer 107 is formed on the anode 105. For this reason, in this embodiment, a cap layer (a layer made of ITO or the like) as in the prior art is not provided between the anode 105 and the hole injection layer 107. Therefore, the display panel 10 according to the present embodiment has a high degree of freedom in cavity design.

  In the display panel 10 according to the present embodiment, the oxygen composition ratio y in AlOy constituting the mixed layer 106 is smaller than the stoichiometric ratio in at least a part of the layer (y <3/2). The insulating layer is relaxed despite having an oxide (having hole injection property), and the mixed layer 106 is interposed between the anode 105 and the hole injection layer 107, whereby the anode 105 The amount of holes injected into the hole injection layer 107 is limited, and it is possible to balance the injection of holes and electrons injected into the organic light emitting layer 110. Therefore, the display panel 10 according to the present embodiment has high luminous efficiency and a long life.

As shown in FIG. 9, in the present embodiment, the lifetime is T ₂ , whereas the lifetime of the comparative example without the mixed layer is T ₁ . For example, the relationship between T ₁ and T ₂ is considered as follows.
[Formula 1] T ₂ = k × T ₁
[Formula 2] 1.1 <k <1.3
As described above, the display panel 10 according to the present embodiment and the organic EL display device 1 including the display panel 10 as a component.
Then, while being able to obtain a high degree of freedom in the cavity design, by suppressing the collapse of the carrier balance, it has high luminous efficiency and a long life.

[Embodiment 2]
A method for manufacturing a display panel according to Embodiment 2 will be described with reference to FIGS. FIG. 10 is a table showing the sputtering conditions for forming the hole injection layer. “Condition 1” in FIG. 10 is a sputtering condition used for forming the hole injection layer 107 according to the first embodiment, and “Condition 2” is a sputtering condition used for forming the hole injection layer according to the present embodiment. is there. The manufacturing method of the display panel according to the present embodiment is the same as that of the first embodiment except for the sputtering conditions related to the formation of the hole injection layer, and thus the description thereof is omitted.

  As shown in FIG. 10, the sputtering conditions (condition 2) according to the present embodiment have the same power and pressure as the sputtering conditions (condition 1) according to the first embodiment, and the introduction of gas into the chamber. This is different from the first embodiment. Specifically, in the sputtering conditions (condition 2) according to the present embodiment, only the inert gas argon (Ar) is introduced in the first half of the sputtering period (step 1), followed by the second half of the period (step 2). ), A mixed gas of argon (Ar) and oxygen (O) is introduced. The mixed gas introduced later in this period has a partial pressure ratio of oxygen (O) to the total pressure of 50 [%] as described above.

Thus, if only argon (Ar) is introduced in the first half of the sputtering period, and then a mixed gas containing oxygen (O) is introduced in the second half of the period, the composition of the mixed layer formed is AlOy. The oxygen composition ratio y becomes smaller than that of the mixed layer 106 according to the first embodiment. For example, it is considered that y = 0.33.
Further, the thickness of the formed mixed layer can also be made thinner than that of the mixed layer 106 of the first embodiment, which is considered more excellent from the viewpoint of ensuring conductivity.

[Modification]
A configuration of the display panel 30 according to the modification will be described with reference to FIG. FIG. 11 shows the configuration of the bank 308 according to the modified example, and the other configuration is the same as that of the display panel 10 according to the first embodiment and the organic EL display device 1 including the same. The description of is omitted.

As shown in FIG. 11, the display panel 30 according to this modification includes a plurality of line-shaped banks 308 that are each formed to extend in the X-axis direction and are parallel to each other. A pixel restriction layer 314 is formed so as to divide a region between adjacent banks 308 in the X-axis direction.
In the display panel 30 according to this modification, subpixels 300 a, 300 b, and 300 c are formed for each recess defined by the line-shaped bank 308.

Note that the laminated structure of the display panel 30 is the same as that of the first embodiment, and the sputtering conditions according to the second embodiment can be employed in forming the hole injection layer.
Since the display panel 30 according to the present modification also has the same stacked configuration as the display panel 10 according to the first embodiment, the same effects as described above can be achieved.

[Other matters]
In the first and second embodiments, the anode 105 is formed using aluminum (Al) or an aluminum alloy (Al alloy). However, a metal electrode having light reflectivity can be used in addition to this. . For example, the anode can be formed using silver (Ag), a silver alloy (Ag alloy), or the like.

In the first and second embodiments, the organic EL display device 1 is used as an example. However, the present invention can be applied to other organic EL elements, and the same effect as described above can be obtained. Can do. For example, the configuration of the present invention can be employed for a signal or the like.
In the first embodiment, the mixed layer 106 is formed so as to be in contact with the entire surface at the interface portion between the anode 105 and the hole injection layer 107. Even when formed in contact, it is possible to at least partially enjoy the above effects.

In the first and second embodiments, the laminated structure in which the anode, the mixed layer, the hole injection layer, the hole transport layer, the organic light emitting layer, the electron transport layer, and the cathode are stacked in this order is adopted. The layers other than the anode, the mixed layer, the hole injection layer, the organic light emitting layer, and the cathode can be omitted as appropriate, and other layers can be interposed.
In the first and second embodiments, as the structure of the hole injection layer 107, the oxide WOx of tungsten (W) is used as an example. However, oxidation of molybdenum (Mo) or nickel (Ni) is also possible. It can also be a layer made of material. Also in this case, a mixed layer is formed between the anode as described above. In this case, a mixed layer of aluminum (Al), oxygen (O), and molybdenum (Mo), or aluminum (Al) and oxygen ( O) and a mixed layer of nickel (Ni). When silver (Ag) or an alloy thereof is used as the anode, a mixed layer of silver (Ag), oxygen (O), and molybdenum (Mo), or silver (Ag), oxygen (O), and nickel ( Ni) and a mixed layer. Even in the case of such a configuration, the same effect as described above can be obtained.

Moreover, the sputtering conditions shown in FIG. 10 are shown as an example, and can be appropriately changed according to the panel size and the like, the layer thickness of the hole injection layer to be formed, and the like.
In the first and second embodiments, the organic EL display device is employed as an example of the organic EL element, but the present invention is not limited to this. The present invention can also be applied as an element such as a lighting device.

  The present invention is useful for realizing an organic EL element having high light emission efficiency and a long lifetime regardless of the driving time.

1. Organic EL display device 10,30. Display panel 20. Drive control part 21-24. Drive circuit 25. Control circuit 100a, 100b, 100c, 300a, 300b, 300c. Subpixel 101. Substrate 102. TFT
103. TFT substrate 104. Interlayer insulating film 106. Mixed layer 107. Hole injection layer 108. Bank 109. Hole transport layer 110. Organic light emitting layer 111. Electron transport layer 113. Sealing layer 114. Functional layer 314. Pixel restriction layer 1050. Anode preparation layers 1060, 1061. Metal oxide layers 1070, 1071. Hole injection preparation layer

Claims (17)

An anode comprising a metal M _A made of aluminum or silver, or an alloy thereof,
A first oxide M _B Ox which is formed above the anode and is an oxide of a metal M _{B made} of tungsten, molybdenum or nickel, and in the first oxide M _B Ox in at least a part of the layer; A first metal oxide layer having a composition ratio x of oxygen smaller than the stoichiometric ratio;
_A second oxide M _A Oy is formed between the anode and the first metal oxide layer so as to be in contact with both the anode and the first metal oxide layer and is an oxide of the same metal as the metal M _{A. A} second metal oxide layer in which the composition ratio y of oxygen in the second oxide M _A Oy in at least a part of the layer is smaller than the stoichiometric ratio;
A light emitting layer provided above the first metal oxide layer and including an organic light emitting material;
A cathode provided above the light emitting layer;
An organic EL element comprising: Wherein the second metal oxide layer, said metal M _B same metal as or organic EL element according to claim 1, wherein it contains also their oxides. The same metal as the metal M _A in the second metal oxide layer, toward the side in contact with the anode on the side in contact with the first metal oxide layer contains a gradient of its concentration gradually decreases according Item 3. The organic EL device according to Item 1 or Item 2. The organic EL element according to any one of claims 1 to 3, wherein a thickness of the second metal oxide layer is less than 10 nm. The organic EL element according to any one of claims 1 to 3, wherein a thickness of the second metal oxide layer is 3 nm or more and 7 nm or less. The organic EL element according to any one of claims 1 to 3, wherein a thickness of the second metal oxide layer is 4 nm or more and 5 nm or less. It said metal M _A is aluminum,
Said metal M _B, the organic EL device according to any one of claims 1 to 6 is tungsten. The organic EL element according to claim 7, wherein in the first metal oxide layer, a composition ratio x of oxygen in the first oxide M _B Ox in at least a part of the layer is smaller than a stoichiometric ratio. The organic EL element according to claim 7 or 8, wherein in the second metal oxide layer, a composition ratio y of oxygen in the second oxide M _A Oy in at least a part of the layer is smaller than a stoichiometric ratio. . The organic EL element according to claim 7 or 8, wherein the composition ratio y is 0.42 or less. The organic EL element according to any one of claims 1 to 10, wherein the first metal oxide layer and the second metal oxide layer have conductivity. Aluminum or silver, or to form an anode preparation layer comprising metal elements M _A consisting of alloys,
The anode preparation layer, at least a partial period oxygen thin film forming method using the introduction with a first oxide comprising a first oxide M _B Ox is an oxide of a metal M _B consisting of tungsten or molybdenum or nickel Forming a metal layer,
Forming a light emitting layer including an organic light emitting material on the first metal oxide layer;
A cathode is provided above the light emitting layer,
During the formation of the first metal oxide layer,
The interface between the anode preparation layer and the first metal oxide layer, in a state in contact with both the anode preparation layer and the first metal oxide layer comprises a second oxide M _A Oy of said metal M _A, the _A second metal oxide layer in which the composition ratio y of oxygen in the second oxide M _A Oy in at least a part of the layer is smaller than the stoichiometric ratio is formed;
After forming the first metal oxide layer,
The portion obtained by removing the second metal oxide layer from the anode preparation layer is an anode,
In the first metal oxide layer, the composition ratio x of oxygen in at least a part of the layer is smaller than the stoichiometric ratio. In the formation of the first metal oxide layer, a mixed gas of an inert gas and oxygen is introduced over the entire period.
The manufacturing method of the organic EL element of Claim 12 . In forming the first metal oxide layer, only an inert gas is introduced in the first half of the period, and a mixed gas of inert gas and oxygen is introduced in the second half of the period.
The manufacturing method of the organic EL element of Claim 12 . A heat treatment is performed after forming the first metal oxide layer.
The method for manufacturing an organic EL device according to any one of claims 12 to 14. As the metal M _A, with aluminum,
As the metal M _B, using tungsten
The method for manufacturing an organic EL device according to any one of claims 15 claim 12. The thickness of the second metal oxide layer is less than 10 nm.
The method for manufacturing an organic EL device of any one of claims 16 claim 12.

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