JP3450304B2 - Electrode body, thin-film EL element provided therewith and method of manufacturing the same, and display device and lighting device provided with thin-film EL element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting display, a thin film EL element applied to illumination such as a backlight for a liquid crystal display, and a manufacturing method thereof.
Further, the present invention relates to a display device and a lighting device including the thin film EL element.

[0002]

2. Description of the Related Art Electroluminescence (hereinafter referred to as EL
Is abbreviated. ) A thin film EL device equipped with a panel is characterized by high visibility, excellent display capability, and high-speed response.

Among these thin film EL devices, various reports have been made so far on organic EL devices containing an organic compound as a constituent material. Among several reports, for example, CW Tang et al. Have published an organic light emitting device (organic EL device) having a structure in which an organic light emitting layer and a hole transport layer are laminated (Applied Physics Letters, 51, 1987, P. 913. ). And to date, research and development of thin film EL devices have been carried out based on this organic light emitting device having a basic structure.

The basic structure of the organic light emitting device will be described below. FIG. 16 is a schematic sectional view schematically showing the structure of a conventional organic light emitting device. As shown in FIG. 1, the organic light emitting device includes a transparent electrode 102, a hole transport layer 103, an electron transport light emitting layer 104, and a cathode 10 on a glass substrate 101.
5 has a structure in which layers are sequentially laminated. In another configuration, the electron transporting light emitting layer 105 may be functionally separated into an electron transporting layer and a light emitting layer.

The thin film EL element means an element in which each functional layer interposed between the transparent electrode 102 and the cathode 105 includes an organic layer, an inorganic layer or a mixed layer of an organic layer and an inorganic layer. . In addition, the organic light emitting element means the transparent electrode 102 and the cathode 10.
This means a case where each of the functional layers interposed between 5 and 5 is an organic layer.

Here, the cathode 105 is a cathode with stable electron injection and easy electron injection, and is made of an alloy of an alkali metal or alkaline earth metal having a low work function and a stable metal such as aluminum or silver. Is used. A specific example of the cathode 105 made of the alloy is disclosed in, for example, JP-A-5-121172.
According to this publication, an alloy composed of aluminum and lithium is used, and the Li concentration is 0.01 wt% or more,
It is described that the control is performed within a minute amount range of 0.1 wt% or less. Then, it is described that an organic light emitting device having high luminous efficiency and high environmental stability is realized by this.

In contrast to the prior art described in the above publication, an organic EL element having a structure in which a metal thin film as an electron injection electrode and an electrode film as a protective electrode are sequentially laminated on an organic layer in place of the cathode 105 is also provided. It is disclosed. The metal thin film is made of a metal material having a low work function such as an alkali metal or an alkaline earth metal, and the electrode film is made of a metal material which is stable against oxygen and water. With this structure, the electrode film
The metal thin film, which is highly reactive to moisture and the like, is protected from the outside, thereby maintaining the electron injection property. Furthermore, Li
Since it is not necessary to control such as a low concentration, it can be manufactured by a simple process.

More recently, as shown in FIG.
An organic light emitting device having a structure in which an electron injection layer 106 is provided between the electron transporting light emitting layer 104 and the cathode 105 is also disclosed (JP-A-9-17574). This electron injection layer 10
An alkali metal compound is used as a material in No. 6, and by optimizing the layer thickness of the electron injection layer 106,
It is described that light can be emitted with high brightness. Furthermore, since the alkali metal compound is chemically stable, it is described that an organic EL element having high reproducibility of characteristics and capable of high-luminance light emission at a low applied voltage can be obtained.

Further, in the case of the electron injection layer made of an insulating material, the relation between the layer thickness and the dark spot (a region not emitting light) has been reported in detail (T. Wakimot).
o, Y.Fukuda, K.Nagayama, A.Yokoi, H.Nakada and M.Tsuch
ida, IEEE Transactions on Electron Devices, Vol.44, N
o.8, p1245, 1997).

Further, the inventors of the present invention have used a specific organometallic complex compound having an alkali metal or an alkaline earth metal as a central metal as a material of the electron injection layer, or an organic light emission using an electron deficient compound. We are developing a device. With the organic light emitting device including the electron injection layer using these materials, a light emitting device having high brightness and long life can be obtained without using a metal material having a low work function.

As described above, in the development of the organic light emitting device, the electron injection layer is an important factor that determines the light emission efficiency and the life, and various improvements have been made from this viewpoint.

Here, when these organic light emitting devices are duty-driven for practical use, the instantaneous brightness is several thousand to
It reaches tens of thousands of cd / m ² . Therefore, when driving the organic light emitting device, it is necessary to maintain high efficiency even in such a high brightness region. Therefore, in the conventional organic light emitting device, it is necessary to further increase the brightness, but for that purpose, it is indispensable to use an electrode containing an alkali metal or an alkaline earth metal, which has an excellent electron injection property.

[0013]

However, in the electrodes using these metal materials having a low work function, the device characteristics may deteriorate due to the alteration of the metal. Therefore, in order to prevent this deterioration, there has been attempted a method of adopting a form using a metal compound having a low work function as described above. In this method, in the case of an inorganic metal compound, sufficient improvement in efficiency and life was not observed. On the other hand, in the case of the organometallic compound, some improvement was achieved against the deterioration of the element characteristics, but in order to further improve it, it is necessary to use a simple metal having a low work function as the material of the electrode. It was

In view of the above, in order to use a simple metal having a low work function and having a high reactivity as an electrode material, there has been a problem that deterioration of the simple metal must be prevented.

[0015]

The present invention has been made to solve the above problems, and an object thereof is to provide a thin film EL containing, for example, an electron injection electrode with a low work function metal having excellent electron injection characteristics. By preventing the deterioration of the metal having a low work function in the element, it is intended to achieve high brightness and long life for practical use.

The inventors of the present application have investigated the determinants of the life characteristics of the thin film EL element and applied a configuration that suppresses the mechanism, thereby maintaining high brightness light emission and high reproducibility of the thin film EL element. We have achieved a longer life. At the same time, a manufacturing method capable of steadily producing a thin film EL element having excellent characteristics was found, and it became possible to provide a high-quality display device and a lighting device.

(Electrode Body) (1) The electrode body according to the first aspect of the present invention has at least two kinds of metals having different work functions, and a low work function other than the metal having the largest work function among the metals. And an electron-deficient substance that accepts electrons emitted from the metal.

According to the above structure, the electron-deficient substance is a strong Lewis acid, and thus captures an electron and becomes an anion. Since this anion can satisfy the octet rule by accepting an electron, a forward reaction is more likely to occur. As a result, it becomes possible to stably exist in the anion state in the electrode body, and the electrode having excellent electron injecting property can be obtained.

In the above-mentioned constitution, the constitution has an electron-deficient substance layer containing the electron-deficient substance, and a metal layer provided on the electron-deficient substance layer and containing an alloy of two or more kinds of metals. Can be

In the above structure, an electron-deficient substance layer containing the electron-deficient substance, a low work function metal layer provided on the electron-deficient substance layer and containing the low work function metal, A protective metal layer provided on the low work function metal layer and containing a metal having the highest work function may be provided.

Further, in the above structure, a low work function metal layer containing the electron deficient substance and the low work function metal, the work function metal layer is provided on the low work function metal layer, and the work function is the highest. A structure having a protective metal layer containing a large metal can be used.

Further, in the above structure, an alloy composed of at least two kinds of metals having different work functions,
The electron-deficient substance may be included in the same layer.

Further, the electron-deficient substance in each of the above constitutions may be a compound represented by the following chemical formula (1).

[0024]

[Chemical 5] (The R ¹ and R ² are a bridging ligand having a nitrogen-containing aromatic ring or a nitrogen-containing aromatic ring derivative having at least one nitrogen atom as a coordinating atom, and halogen or alkyl having 1 to 3 carbon atoms. Any one selected from the group consisting of bridging ligands having the above R ³ , R ⁴ , R ⁵ and R ⁶
Is any one selected from the group consisting of hydrogen, an alkyl, an aryl derivative, and a nitrogen-containing aromatic ring derivative having one nitrogen atom as a coordination atom. The M ¹ is a central metal. )

(2) The electrode body according to the second aspect of the present invention comprises at least two kinds of metals having different work functions,
Among the above metals, a trapping substance for trapping a low work function metal other than the metal having the largest work function in the form of ions is included.

When the low work function metal emits electrons to become cations, the cations have a strong oxidizing action in an attempt to fill the outermost shell orbits that have lost valence electrons with electrons. Since the trapping substance traps the low work function metal in the form of ions, it is possible to prevent the low work function metal from reacting with water or the like to become an insulator such as an oxide. As a result, the life of the electrode body can be extended.

In the above structure, the low work function metal layer provided on the trapping layer and containing the low work function metal, and the work function provided on the low work function metal layer, A protective metal layer containing the largest metal can be used.

Further, in the above-mentioned constitution, the constitution has a trapping layer containing the trapping substance, and a metal layer provided on the trapping layer and containing an alloy of two or more kinds of metals. You can

In the above structure, the low work function metal layer containing the trapping substance and the low work function metal, the work function metal layer provided on the low work function metal layer and having the highest work function are provided. A protective metal layer containing a metal can be provided.

(3) The electrode body according to the third aspect of the present invention comprises at least two kinds of metals having different work functions,
Among the metals, a trapping substance that traps a low work function metal other than the metal having the largest work function in the form of ions, and an electron-deficient substance that receives an electron emitted from the low work function metal are included. To do.

According to the above construction, since the electrode body contains the electron-deficient substance and also the trapping substance, the electron-injecting property can be made excellent and the life can be extended.

In the above structure, the electron-deficient substance layer containing the electron-deficient substance, the trapping layer in contact with the electron-deficient substance layer and containing the trapping substance, and the electron-deficient substance layer or the trapper A low work function metal layer that is in contact with the layer and that includes the low work function metal, and a protective metal layer that is in contact with the low work function metal layer and that includes the metal having the highest work function can be configured. .

Further, in the above structure, an electron-deficient substance layer containing the electron-deficient substance, and a low work function provided on the electron-deficient substance layer and containing the trapping substance and the low work function metal. A structure having a metal layer and a protective metal layer provided on the low work function metal layer and containing a metal having the highest work function can be adopted.

(Thin-Film EL Element) The thin-film EL element according to the present invention can employ the following modes (4) to (6). Here, (1) to (3) are the above first to first
Each corresponds to the third aspect.

(4) The thin film EL element of the present invention corresponding to the first aspect is a hole injecting electrode, an electron injecting electrode paired with the hole injecting electrode, the hole injecting electrode and the electron. The electron injection electrode has a functional layer that is provided between the injection electrode and emits light by an electric field applied by both electrodes, and the electron injection electrode has at least two kinds of metals having different work functions, and a work layer of the metals. An electron deficient substance that accepts electrons emitted from a low work function metal other than the metal having the largest function.

According to the above structure, the electron injecting electrode contains an electron-deficient substance having an excellent electron transporting property, so that electrons can be efficiently injected into the functional layer. As a result,
A thin film EL device with high luminous efficiency can be obtained.

In the above structure, the electron injecting electrode is provided on the functional layer, and is provided on the electron-deficient substance layer containing the electron-deficient substance and on the electron-deficient substance layer. A structure having a metal layer containing two or more kinds of metals having different work functions can be used.

In the above structure, the electron-deficient substance layer may contain the low work function metal.

Further, another thin film EL element of the present invention corresponding to the first aspect is an electron injecting electrode containing at least two kinds of metals having different work functions, and a positive electrode forming a pair with the electron injecting electrode. A hole injecting electrode, a functional layer provided between the electron injecting electrode and the hole injecting electrode, and emitting light by an electric field applied by both electrodes, the functional layer comprising:
At least the electron injection electrode side includes an electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal having the highest work function among the metals.

According to the above structure, since the electron-deficient substance is contained in the functional layer, the transportability of electrons injected from the electron injection electrode in the functional layer can be improved.
Thereby, the luminous efficiency can be improved.

In the above structure, the electron-deficient substance may be uniformly contained within the predetermined range on the electron injection electrode side.

Further, in the above structure, the electron-deficient substance is contained in a predetermined range on the electron injection electrode side, and is distributed in a high concentration toward the electron injection electrode. Can be

Further, in still another thin film EL element of the present invention corresponding to the first aspect, an electron injecting electrode, a hole injecting electrode forming a pair with the electron injecting electrode, and the electron injecting electrode and a positive electrode. A hole injection electrode and a functional layer which emits light by an electric field applied by both electrodes, wherein the functional layer has a low work function metal having a work function smaller than that of the electron injection electrode; And an electron-deficient substance that accepts electrons emitted from a low work function metal.

In the above structure, the electron-deficient substance may be uniformly contained within the predetermined range on the electron injection electrode side.

Further, in the above structure, the electron-deficient substance is contained within the predetermined range on the electron injection electrode side, and is distributed at a higher concentration toward the electron injection electrode. Can be

(5) The thin film EL element of the present invention corresponding to the second aspect is a hole injection electrode, an electron injection electrode paired with the hole injection electrode, the hole injection electrode and an electron. The electron injection electrode has a functional layer that is provided between the injection electrode and emits light by an electric field applied by both electrodes, and the electron injection electrode has at least two kinds of metals having different work functions, and a work layer of the metals. And a trapping substance that traps a low work function metal other than the metal having the largest function in the form of metal ions.

According to the above structure, the trapping substance suppresses the low work function metal from becoming an insulator by trapping in the form of metal ions. Thereby, the electron injection by the low work function metal can be stabilized over a long period of time. Therefore, it is possible to provide a thin film EL element that can emit light with high brightness and has a long emission life.

In the above structure, the electron injecting electrode is provided on the functional layer, is provided on the trapping layer containing the trapping substance, and is provided on the trapping layer. A structure having a metal layer containing more than one kind of metal can be used.

In the above structure, the trapping layer may contain the low work function metal.

Another thin-film EL element of the present invention corresponding to the second aspect is an electron injection electrode containing at least two kinds of metals having different work functions, and a hole injection paired with the electron injection electrode. An electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by both electrodes, wherein the functional layer is on the electron injecting electrode side, Among the metals, a low work function metal other than the metal having the highest work function is included in the form of ions to capture substances.

Even when the functional layer contains a trapping substance as in the above-mentioned structure, it is possible to suppress the trapping of the low work function metal in the form of metal ions to form an insulator. As a result, it is possible to provide a thin film EL element having high brightness and long life.

In the above structure, the trapping substance may be uniformly contained within the predetermined range on the electron injection electrode side.

Further, in the above structure, the trapping substance may be contained within the predetermined range on the electron injection electrode side, and may be distributed at a higher concentration toward the electron injection electrode. .

According to still another thin film EL element of the present invention corresponding to the second aspect, an electron injection electrode, a hole injection electrode paired with the electron injection electrode, the electron injection electrode and the hole injection. A functional layer which is provided between the electrode and emits light by an electric field applied by both electrodes, the functional layer being a low work function metal having a work function smaller than that of the electron injecting electrode; And a trapping substance that traps the functional metal in the form of ions.

In the above structure, the low work function metal and the trapping substance may be uniformly contained within the predetermined range on the electron injection electrode side.

Further, in the above structure, the low work function metal and the trapping substance are contained within the predetermined range on the electron injection electrode side, and are distributed in a higher concentration toward the electron injection electrode. You may have.

(6) The thin film EL element of the present invention corresponding to the third aspect is a hole injecting electrode, an electron injecting electrode paired with the hole injecting electrode, the hole injecting electrode and the electron. The electron injection electrode has a functional layer that is provided between the injection electrode and emits light by an electric field applied by both electrodes, and the electron injection electrode has at least two kinds of metals having different work functions, and a work layer of the metals. An electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal having the largest function, and a trapping substance that traps the low work function metal in the form of ions.

According to the above structure, the electron injecting electrode has an electron deficient substance, and therefore has an excellent electron injecting property to the functional layer. Therefore, the luminous efficiency can be improved. Further, since it also has a trapping substance, it is possible to prevent the low work function metal from deteriorating and becoming an insulator. As a result, it becomes possible to continuously inject electrons into the functional layer in a stable manner, and the life of the device can be extended.

In the above structure, the electron injecting electrode has two or more kinds of the electron-deficient substance layer containing the electron-deficient substance, a trapping layer in contact with the electron-deficient substance layer and containing the trapping substance. And a metal layer containing the above metal.

In the above structure, the electron injection electrode includes an electron-deficient substance layer containing the electron-deficient substance, and a trapping layer in contact with the electron-deficient substance layer and containing the trapping substance and a low work function metal. Can be provided.

Further, another thin film EL element of the present invention corresponding to the third aspect is an electron injecting electrode containing at least two kinds of metals having different work functions, and a positive electrode forming a pair with the electron injecting electrode. A hole injecting electrode, a functional layer provided between the electron injecting electrode and the hole injecting electrode, and emitting light by an electric field applied by both electrodes, the functional layer comprising:
An electron-deficient substance that accepts an electron emitted from a low work function metal other than the metal having the highest work function among the metals, and a trapping substance that traps the low work function metal in the form of ions. To do.

Even when the functional layer contains an electron-deficient substance and a trapping substance as in the above-mentioned constitution, the luminous efficiency can be improved and the device can have high brightness and long life.

In the above structure, the electron-deficient substance and the trapping substance may be uniformly contained within the predetermined range on the electron injection electrode side.

In the above-mentioned structure, the electron-deficient substance and the trapping substance are contained within the predetermined range on the electron injection electrode side, and are distributed in a high concentration toward the electron injection electrode. Good.

Further, a thin film EL element according to still another aspect of the present invention, which corresponds to the third aspect, has an electron injecting electrode, a hole injecting electrode paired with the electron injecting electrode, and the electron injecting electrode and a positive electrode. A hole injection electrode, and has a functional layer that emits light by an electric field applied by both electrodes, the functional layer, a low work function metal having a work function smaller than the electron injection electrode, It is characterized by including a trapping substance that traps a low work function metal in the form of ions, and an electron-deficient substance that receives an electron emitted from the low work function metal.

In the above structure, the low work function metal, the electron deficient substance and the trapping substance may be uniformly contained within the predetermined range on the electron injection electrode side.

Further, in the above structure, the low work function metal, the electron-deficient substance and the trapping substance are contained within a predetermined range on the electron injection electrode side, and the closer to the electron injection electrode, the closer. It may be distributed in a high concentration.

Further, in still another thin film EL element of the present invention corresponding to the third aspect, an electron injection electrode containing at least two kinds of metals having different work functions is paired with the electron injection electrode. A hole injection electrode and a functional layer provided between the electron injection electrode and the hole injection electrode and emitting light by an electric field applied by both electrodes; One of an electron-deficient substance that accepts electrons emitted from a low work function metal other than, or a trapping substance that traps the low work function metal in the form of ions, is included in the electron injecting electrode, and the other is It is characterized in that it is included in the functional layer.

(Manufacturing Method of Thin Film EL Element) As the method of manufacturing the thin film EL element described above, the following modes (7) to (9) can be adopted. Here, (7) to (9) correspond to the above-mentioned aspects (4) to (6), respectively.

(7) In the method of manufacturing a thin film EL element of the present invention, which corresponds to the first aspect, at least between the electron injecting electrode and the hole injecting electrode containing at least two kinds of metals having different work functions. A method for manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes,
The electron injecting electrode forms an electron-deficient substance layer containing, on the functional layer side, an electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal having the highest work function among the metals. By performing at least a material layer forming step and a metal layer forming step of forming a metal layer containing the two or more kinds of metals on the side opposite to the functional layer,
The electron injection electrode is formed.

Further, another method of manufacturing a thin film EL element of the present invention, which corresponds to the first aspect, is a method for producing a thin film EL element between an electron injecting electrode and a hole injecting electrode containing at least two kinds of metals having different work functions. In the method of manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes, the electron injecting electrode has a work function other than a metal having the largest work function among the metals on the functional layer side. It is formed by performing at least an electron-deficient substance layer forming step of forming an electron-deficient substance layer containing a low work-function metal and an electron-deficient substance that accepts electrons emitted from the low work-function metal. To do.

Further, according to still another method of manufacturing a thin film EL element of the present invention, which corresponds to the first aspect, an electron injecting electrode and a hole injecting electrode containing at least two kinds of metals having different work functions are provided. A method for manufacturing a thin film EL device having a functional layer that emits light by an electric field applied between both electrodes, wherein electrons emitted from a low work function metal other than the metal having the largest work function are included. The method is characterized by including the step of forming the functional layer so that the electron-deficient substance to be received is distributed at least on the electron injection electrode side.

Further, according to still another method of manufacturing a thin film EL element of the present invention corresponding to the first aspect, light is emitted by an electric field applied between the electron injection electrode and the hole injection electrode by both electrodes. And a low work function metal other than the metal having the highest work function among the metals, and an electron-deficient substance that accepts electrons emitted from the low work function metal. And a step of forming the functional layer so as to be distributed at least on the electron injection electrode side.

According to each of the above-mentioned methods, the deterioration of the low work function metal can be prevented, so that a thin film EL element with high emission brightness can be manufactured. Further, for example, when the electron injection electrode is composed of the electron deficient substance layer and the metal layer containing the low work function metal, the layer thickness of the metal layer can be further reduced, so that the workability can be improved. In addition, since variations in emission luminance within the plane can be suppressed, the element can be manufactured with high reproducibility and the reliability of the manufacturing process can be improved. Further, the yield can be improved.

(8) The method of manufacturing a thin film EL element of the present invention corresponding to the second aspect is such that at least an electron injecting electrode and a hole injecting electrode containing two or more kinds of metals having different work functions are provided. A method of manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes,
The electron injection electrode, on the functional layer side, a trapping layer forming step of forming a trapping layer containing a trapping substance for trapping a low work function metal other than the metal having the largest work function among the metals in the form of ions, It is formed by performing at least a metal layer forming step of forming a metal layer containing an alloy composed of two or more kinds of metals on the side opposite to the functional layer.

Further, another method of manufacturing a thin film EL element according to the present invention, which corresponds to the second aspect, is that at least between an electron injection electrode and a hole injection electrode containing two or more kinds of metals having different work functions. In the method of manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes, the electron injecting electrode is a metal other than the metal having the highest work function among the metals on the functional layer side. And a trapping layer forming step for forming a trapping layer containing a trapping substance for trapping a low work function metal in the form of ions, and a metal layer containing an alloy composed of two or more kinds of metals on the side opposite to the functional layer. It is characterized by being formed by performing at least the forming step of forming a metal layer.

Further, another method of manufacturing a thin film EL element of the present invention corresponding to the second aspect is such that at least an electron injection electrode containing at least two kinds of metals having different work functions and a hole injection electrode are provided. In the method for manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes, a low work function metal other than the metal having the largest work function is trapped in the form of ions. And a step of forming the functional layer so that the trapping substance is distributed at least on the electron injection electrode side.

Further, according to another method of manufacturing a thin film EL element of the present invention, which corresponds to the second aspect, light is emitted between the electron injecting electrode and the hole injecting electrode by an electric field applied by both electrodes. A method of manufacturing a thin film EL device having a functional layer, wherein a low work function metal other than the metal having the largest work function among the metals, and a trapping substance that traps the low work function metal in the form of ions, The method is characterized by including a step of forming the functional layer so as to be distributed at least on the electron injection electrode side.

According to each of the above-mentioned methods, since the trapping substance traps the low work function metal which becomes a cation in the manufacturing process, it is possible to suppress the deterioration of the low work function metal. As a result, it is possible to manufacture a thin film EL element with high emission brightness. Further, for example, when the electron injection electrode is composed of a trapping layer and a metal layer containing a low work function metal, the layer thickness of the metal layer can be further reduced. As a result, workability can be improved. In addition, since variations in emission luminance within the plane can be suppressed, the element can be manufactured with high reproducibility and the reliability of the manufacturing process can be improved. Further, the yield can be improved.

(9) In the method of manufacturing a thin film EL element of the present invention, which corresponds to the third aspect, at least between the electron injection electrode and the hole injection electrode containing two or more kinds of metals having different work functions. A method of manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes,
The electron injection electrode, an electron-deficient substance layer forming step of forming an electron-deficient substance layer containing an electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal whose work function is the largest, A trapping layer forming step of forming a trapping layer containing a trapping substance for trapping the low work function metal in the form of ions; and forming a metal layer containing the two or more kinds of metals on the electron-deficient substance layer or the trapping layer. It is formed by performing at least the metal layer forming step.

The method of manufacturing a thin film EL element according to another aspect of the present invention, which corresponds to the third aspect, is characterized in that at least an electron injection electrode and a hole injection electrode containing two or more kinds of metals having different work functions are included. In the method of manufacturing a thin film EL element having a functional layer that emits light by an electric field applied by both electrodes, the electron injecting electrode is a low work function metal other than the metal having the largest work function among the metals. Formed by performing at least a step of forming a layer containing an electron-deficient substance that accepts electrons emitted from the low work function metal and a trapping substance that traps the low work function metal in the form of ions. Characterize.

Further, another method of manufacturing a thin film EL element according to the present invention, which corresponds to the third aspect, is provided between an electron injection electrode and a hole injection electrode containing at least two kinds of metals having different work functions. In the method of manufacturing a thin film EL device having a functional layer that emits light by an electric field applied by both electrodes, the electron injecting electrode is made of a low work function metal other than the metal having the largest work function. An electron-deficient substance layer forming step of forming an electron-deficient substance layer containing an electron-deficient substance that accepts emitted electrons, and the low work function metal,
And a trapping layer forming step of forming a trapping layer containing a trapping substance for trapping the low work function metal in the form of ions.

Further, according to still another method of manufacturing a thin film EL element of the present invention, which corresponds to the third aspect, an electron injecting electrode and a hole injecting electrode containing at least two kinds of metals having different work functions are provided. A method for manufacturing a thin film EL device having a functional layer that emits light by an electric field applied between both electrodes, wherein electrons emitted from a low work function metal other than the metal having the largest work function are included. The method is characterized by including the step of forming the functional layer such that the electron-deficient substance to be received and the trapping substance to trap the low work function metal in the form of ions are distributed at least on the electron injection electrode side.

Further, according to another method of manufacturing a thin film EL element of the present invention corresponding to the third aspect, light is emitted between an electron injection electrode and a hole injection electrode by an electric field applied by both electrodes. A method of manufacturing a thin film EL device having a functional layer, comprising a low work function metal other than the metal having the highest work function among the metals, and an electron deficient substance that accepts electrons emitted from the low work function metal. And a step of forming the functional layer so that the trapping substance that traps the low work function metal in the form of ions is distributed at least on the electron injection electrode side.

According to each of the above-mentioned methods, the electron deficient substance and the trapping substance prevent the low work function metal from deteriorating, so that it is possible to manufacture a thin film EL element having a high emission luminance.
Further, since the workability can be improved and the reproducibility is good, the reliability of the manufacturing process can be further enhanced. Further, the yield can be improved.

The display device according to the present invention can employ the following aspects (10) to (12). Here, (10) to (12) correspond to the above-described first to third aspects, respectively.

(10) In the display device of the present invention corresponding to the first aspect, an electron injection electrode containing at least two kinds of metals having different work functions, and a hole injection paired with the electron injection electrode. A display device comprising a thin film EL element having an electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the both electrodes, wherein the electron injecting device is provided. The electrode is characterized by containing an electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal having the highest work function among the metals.

Further, another display device according to the present invention corresponding to the first aspect is a hole injecting electrode, an electron injecting electrode paired with the hole injecting electrode, the hole injecting electrode and the electron. What is claimed is: 1. A display device comprising a thin film EL element having a functional layer which is provided between an injection electrode and emits light by an electric field applied by the both electrodes, wherein the electron injection electrode or the functional layer has the electron injection A low work function metal having a work function smaller than that of a metal forming the electrode is contained, and the functional layer contains an electron-deficient substance that accepts electrons emitted from the low work function metal. .

(11) In the display device of the present invention corresponding to the second aspect, an electron injection electrode containing at least two kinds of metals having different work functions, and a hole injection electrode paired with the electron injection electrode. And a thin film EL element having a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the both electrodes, the electron injecting electrode Is a low work function metal other than the metal having the largest work function among the above metals,
It is characterized by containing a trapping substance which traps in the form of ions.

Another display device of the present invention corresponding to the second aspect is a hole injection electrode, an electron injection electrode paired with the hole injection electrode, the hole injection electrode and the electron injection electrode. A display device comprising a thin film EL element having a functional layer provided between the electron injection electrode and the functional layer, the functional layer emitting light by an electric field applied by both electrodes,
A low work function metal having a work function smaller than that of the metal forming the electron injecting electrode is contained, and the functional layer contains a trapping substance that traps the low work function metal in the form of ions. And

(12) In the display device of the present invention corresponding to the third aspect, an electron injection electrode containing at least two kinds of metals having different work functions, and a hole injection paired with the electron injection electrode. A display device comprising a thin film EL element having an electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the both electrodes, wherein the electron injecting device is provided. The electrode includes an electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal having the highest work function among the metals, and a trapping substance that traps the low work function metal in the form of metal ions. It is characterized by including.

Further, another display device of the present invention corresponding to the third aspect is a hole injection electrode, an electron injection electrode paired with the hole injection electrode, the hole injection electrode and an electron. What is claimed is: 1. A display device comprising a thin film EL element having a functional layer which is provided between an injection electrode and emits light by an electric field applied by the both electrodes, wherein the electron injection electrode or the functional layer has the electron injection A low work function metal having a work function smaller than that of the metal forming the electrode is included, and the functional layer receives electrons emitted from a low work function metal other than the metal having the highest work function. Electron-deficient substances that
And a trapping substance that traps the low work function metal in the form of ions.

Further, in still another display device of the present invention corresponding to the third aspect, an electron injection electrode containing at least two kinds of metals having different work functions, and a positive electrode paired with the electron injection electrode. A display device comprising a thin film EL element having a hole injecting electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the two electrodes. Among the metals, a low work function metal other than the metal having the largest work function, a trapping substance that traps in the form of metal ions, or an electron-deficient substance that accepts electrons emitted from the low work function metal is one of the above. It is characterized in that it is included in the electron injection electrode and the other is included in the functional layer.

According to each of the above-mentioned configurations, a high-quality display device can be provided by using a thin film EL element having high luminous efficiency and high reliability. Further, for example, high-quality image display is possible even when the duty driving is performed, and high reliability can be ensured by suppressing a long life reduction.

The illumination device according to the present invention can employ the following modes (13) to (15). Here, (13) to (15) correspond to the above-described first to third aspects, respectively.

(13) The illumination device of the present invention, which corresponds to the first aspect, has an electron injection electrode containing at least two kinds of metals having different work functions, and a hole injection paired with the electron injection electrode. A lighting device comprising a thin film EL element having an electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the both electrodes. The electrode is characterized by containing an electron-deficient substance that accepts electrons emitted from a low work function metal other than the metal having the highest work function among the metals.

Further, another illumination device of the present invention corresponding to the first aspect is a hole injecting electrode, an electron injecting electrode paired with the hole injecting electrode, the hole injecting electrode and the electron. What is claimed is: 1. A lighting device comprising a thin film EL element having a functional layer provided between an injection electrode and emitting light by an electric field applied by both electrodes, wherein the electron injection electrode or the functional layer has the electron injection function. A low work function metal having a work function smaller than that of the metal forming the electrode is contained, and the functional layer contains an electron deficient substance that accepts electrons emitted from the low work function metal. To do.

(14) The illumination device of the present invention, which corresponds to the second aspect, includes an electron injection electrode containing at least two kinds of metals having different work functions, and a hole injection paired with the electron injection electrode. A lighting device comprising a thin film EL element having an electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the both electrodes. The electrode is characterized in that it contains a trapping substance for trapping a low work function metal other than the metal having the highest work function among the metals in the form of ions.

Further, in another illuminating device of the present invention corresponding to the second aspect, a hole injection electrode, an electron injection electrode paired with the hole injection electrode, the hole injection electrode and an electron. What is claimed is: 1. A lighting device comprising a thin film EL element having a functional layer provided between an injection electrode and emitting light by an electric field applied by both electrodes, wherein the electron injection electrode or the functional layer has the electron injection function. A low work function metal having a work function smaller than that of the metal forming the electrode is contained, and the functional layer is characterized by containing a trapping substance that traps the low work function metal in the form of ions.

(15) The illumination device of the present invention, which corresponds to the third aspect, has an electron injection electrode containing at least two kinds of metals having different work functions and a hole injection paired with the electron injection electrode. A lighting device comprising a thin film EL element having an electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the both electrodes. The electrode, an electron-deficient substance that accepts electrons emitted from a low work function metal metal other than the metal having the highest work function among the metals, and a trapping substance that traps the low work function metal in the form of metal ions. It is characterized by including.

Further, another illumination device of the present invention corresponding to the third aspect is a hole injection electrode, an electron injection electrode paired with the hole injection electrode, the hole injection electrode and an electron. What is claimed is: 1. A lighting device comprising a thin film EL element having a functional layer provided between an injection electrode and emitting light by an electric field applied by both electrodes, wherein the electron injection electrode or the functional layer has the electron injection function. A low work function metal having a work function smaller than that of the metal forming the electrode is included, and the functional layer receives electrons emitted from a low work function metal other than the metal having the highest work function. Electron-deficient substances that
And a trapping substance that traps the low work function metal in the form of ions.

Further, in still another illumination device of the present invention corresponding to the third aspect, an electron injection electrode containing at least two kinds of metals having different work functions, and a positive electrode paired with the electron injection electrode. A lighting device comprising a thin film EL element having a hole injecting electrode and a functional layer provided between the electron injecting electrode and the hole injecting electrode and emitting light by an electric field applied by the two electrodes, Among the metals, a low work function metal other than the metal having the largest work function, a trapping substance that traps in the form of metal ions, or an electron-deficient substance that accepts electrons emitted from the low work function metal is one of the above. It is included in the electron injection electrode, and the other is included in the functional layer.

According to the above-mentioned constitutions, it is possible to provide a lighting device which is a surface light emitter and is flexible. As a result,
It is possible to provide a new lighting device and create a new lighting space without causing a loss of brightness due to conventional indirect lighting or the like.

[0104]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

(Embodiment 1) An embodiment of a thin film EL element according to the present invention will be described below. FIG. 1 is a schematic sectional view showing a thin film EL element according to the first embodiment.

As shown in the figure, the thin film EL element 10 according to the present embodiment has at least a hole injection electrode 12 and an electron injection electrode 14 paired with the hole injection electrode 12 on a substrate 11. The functional layer 13 provided between the hole injection electrode 12 and the electron injection electrode 14 is laminated.

The substrate 11 is the hole injection electrode 1 described above.
Any material capable of supporting 2 or the like may be used. Furthermore, the functional layer 13
When the light emitted at is taken out from the substrate 11 side,
It may be transparent or semi-transparent to visible light. As such, for example, Corning 1737
Examples include glass substrates such as (trade name, manufactured by Corning) and other resin film substrates such as polyester.

The hole injecting electrode 12 allows holes to function in the functional layer 1
3 is an electrode having a function of injecting. When the light emitted from the functional layer 13 is extracted from the substrate 11 side, the hole injection electrode 12 needs to be transparent or semitransparent. In this case, as the hole injection electrode 12, for example, IT
An O (indium tin oxide) film can be used.
In addition to ITO, SnO (tin oxide), Ni (nickel), Au (gold), Pt (platinum), Pd (palladium), or the like can be used.

The layer thickness of the hole injection electrode 12 is determined from the required sheet resistance value and visible light transmittance. However, since the thin film EL element has a higher driving current density than that of a liquid crystal display element, it is preferable to reduce the sheet resistance value. Therefore, the hole injection electrode 12 is often used with a layer thickness of 100 nm or more.

The functional layer 13 has a function of emitting light mainly when an electric field is applied. The functional layer 13 is
It may be composed of a single light emitting layer, or may have a layered structure in which a plurality of layers are laminated to separate the functions. In the case of the layer structure, the thin film EL element according to the present invention can adopt various aspects. Hereinafter, a case where a hole transport layer, a light emitting layer, and an electron transport layer are sequentially stacked from the substrate 11 side will be described as an example.

The hole transport layer has a function of receiving holes from the hole injection electrode 12 and transporting them to the light emitting layer. Further, it also has a function of preventing the invasion of electrons. As a material used for the hole transport layer, for example, JP-A-7-12
Japanese Patent No. 6615, tetraphenylbenzidine compound, triphenylamine trimer and benzidine dimer,
Various triphenyldiamine derivatives described in JP-A-8-48656 and N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1 described in JP-A-7-69558. Examples include'-biphenyl-4,4'-diamine (MTPD) and the triphenylamine tetramer described in JP-A-10-228982. Further, among the exemplified materials, a derivative having triphenylamine as a basic skeleton is preferable, and triphenylamine tetramer is particularly preferable.

The electron transport layer has a function of receiving electrons from the electron injection electrode 14 and transporting them to the light emitting layer. Further, it also has a function of preventing the invasion of holes. As a material used for the electron transport layer, for example, tris (8-quinolinolato) aluminum (hereinafter abbreviated as Alq) is preferable. In addition to Alq, tris (4-
Examples thereof include metal complexes such as methyl-8-quinolinolato) aluminum and 3- (2′-benzothiazolyl) -7-diethylaminocoumarin. As the material for the hole transport layer and the electron transport layer, in addition to the organic materials listed above, p
It is also possible to employ an inorganic material forming the layer or the n layer.

The layer thickness of the hole transport layer and the electron transport layer is
It is preferably in the range of 10 to 1000 nm.
Further, these layers can be composed of a plurality of layers. That is, when the hole transport layer has a plurality of layers, the layers can be stacked so that the ionization potential becomes smaller as the hole transport layer becomes closer to the light emitting layer. Further, when the electron transport layer is composed of a plurality of layers, the respective layers can be laminated so that the electron affinity becomes larger as the layer is closer to the light emitting layer.

In the light emitting layer, holes injected from the hole transport layer are combined with electrons injected from the electron transport layer,
The layer whose binding energy is emitted as light. Examples of the light emitting layer include a hole transporting light emitting layer, an electron transporting light emitting layer, and a bipolar light emitting layer. Further, as the material used for the light emitting layer, in addition to Alq or its derivative, coumarin 6, DCM (4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) is added to these compounds. Alternatively, a dye doped with phenoxazone 9 may be used. Further, triphenylamine doped with rubrene can also be used.
Further, not only the above-mentioned organic material but also an inorganic fluorescent material can be used. When using this inorganic fluorescent material,
For example, the inorganic fluorescent material may be dispersed in a polymer matrix to form the coating.

Thus, the functional layer 13 has been described by taking the case of the layer structure of hole transport layer / light emitting layer / electron transport layer as an example, but the present invention is not limited to this.
For example, it may have a layer structure of light emitting layer / electron transport layer or hole transport layer / light emitting layer, or may have a layer structure of hole transport layer / carrier block layer / electron transport layer. Further, a layer structure in which a hole blocking layer such as bathocuproine is laminated between the hole transporting layer and the electron transporting layer so that the hole transporting layer emits light can be employed. Alternatively, the light emitting layer may be used alone.

Each layer constituting the functional layer 13 such as the hole transport layer, the electron transport layer and the light emitting layer described above preferably has a homogeneous film structure in an amorphous state. When the film structure is crystallized, it becomes necessary to increase the driving voltage of the device,
Also, the efficiency of injecting charge carriers is reduced and the device characteristics are deteriorated.

The electron injecting electrode 14 is composed of a metal layer 15 containing at least two kinds of metals having different work functions and an electron deficient substance layer 16 containing an electron deficient substance. It has injection as a basic function.

The metal layer 15 may be an alloy composed of, for example, a metal having a small work function and a low electron injection barrier, and a metal having a large work function and stability as compared with this metal. Further, it may be a laminated electrode in which a plurality of metal layers described later are laminated.

Examples of the alloys include Mg-Ag alloys and Al-Li alloys proposed by Tang et al.
In addition, Ca-Ag alloy, Li-Al-Zn alloy, Ca-A
l alloy, Mg-Al alloy, Sn-Al-Li alloy, Bi
-Al-Li alloy, In-Al-Li alloy, etc. can also be adopted. Metal with low work function (low work function metal)
Means a metal having a relatively small work function as compared with the above-mentioned stable metals. Specifically, Li, Na, K, R
Alkali metal composed of b, Cs and Fr, Be, M
An alkaline earth metal or the like composed of g, Ca, Sr, Ba and Ra is preferable. Since these low work function metals have the property of easily emitting electrons, it becomes extremely easy to inject electrons into the light emitting layer, and it is possible to increase the brightness of the thin film EL element. The electrons emitted by the low work function metal are the valence electrons in the outermost shell. For example, an alkali metal such as Li emits an electron of 2s orbital, and an alkaline earth metal such as Na emits an electron of 3s orbit. The functional metal becomes a cation (positive ion).

Further, the electron injection electrode 14 contains a metal having a work function larger than that of the low work function metal.
This metal having a high work function serves to protect the low work function metal and prevent deterioration. Since a low work function metal has a high reactivity with respect to water, oxygen, etc., by making this low work function metal an alloy with a more stable metal, it is possible to protect it from water etc. in the air. As a result, electrons can be stably injected into the functional layer 13. Here, as the metal having a large work function, for example, Al, Z
Examples include n, Ag, In, Sn, Bi, Pd, Cu and the like.

The electron-deficient substance layer 16 contains at least an electron-deficient substance. What is an electron-deficient substance?
It is a substance whose number of valence electrons is insufficient compared to the number of valence orbitals. As the electron-deficient substance, Li, Be, Mg, B, Z
Various electron-deficient organometallic compounds and electron-deficient inorganic metal compounds obtained by multicentric bonding of atoms that easily form electron-deficient substances such as n and Al with other atoms are applicable.

Examples of the electron-deficient organometallic compound include, for example, alkylated Al which is stabilized by forming a 3-center 2-electron bond, and a compound represented by the following chemical formula (1).

[0123]

[Chemical 6]

Here, R ¹ and R ² are a bridging ligand having a nitrogen-containing aromatic ring having at least one nitrogen atom as a coordinating atom or a ring derivative thereof, or a halogen atom or an alkyl group having 1 to 3 carbon atoms. bridging ligand der with
The nitrogen in the nitrogen-containing aromatic ring serves as a coordination atom . In the bridging ligand having a nitrogen-containing aromatic ring containing at least one nitrogen atom, examples of the bridging ligand having a nitrogen-containing aromatic ring containing one nitrogen atom include pyrrole, pyridine, oxazole and 3 , 3'-bipyridine-
5,5'-diyl etc. can be illustrated. Further, as a bridging ligand having a nitrogen-containing aromatic ring containing two or more nitrogen atoms, imidazole, pyrazole, pyridazine, pyrazine, pyrimidine, phthalazine, 1H-indazole, oxadiazole, 9,10-phenanthroline, triazole,
Examples include triazine, tetrazine, and tetrazole. Further, as the halogen, F, Cl, Br, I,
At can be exemplified. Further, examples of the bridging ligand having an alkyl having 1 to 3 carbon atoms include methyl, ethyl and butyl.

Any of R ³ , R ⁴ , R ⁵ and R ⁶ is selected from the group consisting of hydrogen, an alkyl derivative, an aryl derivative and a nitrogen-containing aromatic ring derivative having one nitrogen atom as a coordinating atom. Examples of the alkyl include methyl, ethyl and the like. Examples of the aryl derivative include phenyl, tolyl, pyridyl, triazole, tetrazole, indazole and the like.
Examples of the nitrogen-containing aromatic ring derivative include pyrrole, indole, isoindole, carbazole and the like. Further, M ¹ is any one metal element or metalloid element selected from the atomic group consisting of Be, Mg, Ca, B, Al and Ga.

Specific examples of the compound represented by the chemical formula (1) include, for example, 4,4,8,8-tetraethylpyrazaball, 1,3,5,7-tetramethylpyrazaball, and pyrazabole. Can be mentioned.

As the electron-deficient inorganic metal compound, L
Examples thereof include iH and BeH ₂ . In particular, when the functional layer 13 in contact with the cathode is composed of an organic compound, the above-mentioned electronic organometallic complex compound is preferable.

Since this electron-deficient substance does not complete the closed shell, it has a strong electron accepting property and an excellent electron transporting property. Therefore, in the past, an electron-deficient substance was sometimes used as an electron injection material without using a low work function metal.

Incidentally, for reference, at present, the description of the bond between neutral molecules is based on the Lewis-Langmuir's theory of valency. However, for this electron-deficient substance, it is difficult to apply the theory to explain the bonding state. However, electron-deficient substances can be easily explained by the theory of combining several atomic orbitals to form molecular orbitals. Further details of electron-deficient substances are described in inorganic chemistry books, physicochemical dictionaries, etc.

The electron-deficient substance layer 16 containing such an electron-deficient substance was provided in the electron injecting electrode 14 in order to investigate the deterioration mechanism of the low work function metal described below and to have an idea of this deterioration mechanism. by.

Li is cited as an example of the low work function metal, and the mechanism for suppressing deterioration of the low work function metal will be described.
First, Li contained in the electron injection electrode 14 emits electrons to become Li cations as shown in the following reaction formula (3).

[0132]

[Chemical 7]

If the reaction equation (3) reversibly and continuously exchanges electrons, the deterioration of Li should not occur. However, the Li cation is very reactive and has a strong oxidizing action. Therefore, the Li cation easily reacts with nitrogen or the like existing in the element or in the storage environment of the element when it is generated. That is, Li nitride (insulator) is generated, and the reaction formula (3) becomes irreversible. As a result, the stable electron injecting ability with respect to the functional layer 13 is lowered, and the element is deteriorated.

On the other hand, the metal layer 1 is formed on the electron-deficient material layer 16.
When electrons are injected from 5, the electron-deficient substance is a strong Lewis acid, so the electrons are trapped by the electron-deficient substance.
As a result, an anion (A ⁻ ) is generated.

[0135]

[Chemical 8] In the formula, A represents an electron-deficient substance.

Here, since A ⁻ can satisfy the octet rule by accepting an electron, a forward reaction is more likely to occur. Therefore, it can continue to exist stably in the anion state. As a result, the electron-deficient substance layer 16 containing the electron-deficient substance functions as a layer having an extremely excellent electron transport property, and more electrons can be injected into the light emitting layer. As a result, the recombination rate of holes and electrons can be increased and the luminous efficiency can be improved.

Also, since this A ⁻ acts as a weak Lewis base against the Li cation, the reaction represented by the following reaction formula (5) occurs at the interface between the electron injection electrode 14 and the electron deficient material layer 16, and the complex is formed. To form. Further, a part of the Li cations penetrates into the electron-deficient substance layer 16 by ablation, so that the reaction also occurs inside the electron-deficient substance layer 16.

[0138]

[Chemical 9]

Next, the Lewis acid (A) and Li neutral molecules are returned from the intermediate in the state of this ion complex. That is, the electron-deficient substance prevents the low work function metal from changing to an oxide, a nitride, or the like, so that the high electron injection property of the electron injection electrode 14 can be maintained. As a result, the life of the device can be extended while realizing high-luminance light emission.

The average layer thickness of the electron-deficient substance layer 16 is
It is preferably in the range of 0.1 to 100 nm. When the electron-deficient substance layer 16 is a monolayer having a substantially uniform layer thickness, the layer thickness is about 0.1 nm or more depending on the kind of the electron-deficient substance, and the electron-deficient substance layer 16 having a thinner layer thickness than that. Is difficult to form. On the other hand, when the layer thickness is larger than 100 nm, the applied voltage rises and the element is deteriorated, which is not preferable.

Next, a method of manufacturing the thin film EL element according to the first embodiment will be described. First, the hole injection electrode 12 is formed on the substrate 11 by a conventionally known method. Specifically, for example, when the hole injection electrode 12 is an ITO film, a film forming method such as a sputtering method, an electron beam evaporation method, an ion plating method can be adopted. Adopting these film forming methods can improve the transparency of the ITO film and reduce the resistivity.

Then, the functional layer 13 is formed on the electron injection electrode 14.
To form. As described above, the functional layer 13 can adopt various aspects, for example, the functional layer 13
When forming the hole transport layer, the light emitting layer, and the electron transport layer in order from the side, it is preferable to adopt a vacuum vapor deposition method as a film forming method of each layer. This is because this method enables the formation of a homogeneous thin film in an amorphous state. Furthermore,
By forming each layer continuously in a vacuum, it is possible to prevent impurities from adhering to the interface between the layers. As a result, it is possible to improve characteristics such as lowering of operating voltage, higher efficiency, and longer life. Further, in forming each of these layers by a vacuum vapor deposition method, when a certain layer contains a plurality of compounds, co-evaporation is performed by individually controlling the temperature of each boat (a container loaded with a vapor deposition base material) containing each of these compounds. Preferably. Furthermore,
A mixture of these compounds in advance may be vapor-deposited. Further, as a film forming method other than the vacuum vapor deposition method, other solution coating methods such as a spin coating method, a dipping method, a casting method and a Langmuir-Blodgett (LB) method can be adopted. In the case of the solution coating method, each compound may be dispersed in a matrix substance such as a polymer.

Next, the electron-deficient material layer 16 is formed on the functional layer 13 by the vacuum vapor deposition method. The vapor deposition conditions are not particularly limited and may be appropriately set so that a desired thin film is formed. Specifically, for example, the deposition rate is 0.
01 to 0.5 nm / sec, vacuum pressure 10 ³ to 10 ⁶ Pa
If the vapor deposition is performed under these conditions, the electron-deficient substance layer 16 having a good film structure can be formed.

Next, the metal layer 15 is formed on the electron-deficient material layer 16 by, for example, the vapor deposition method or the sputtering method. Here, the low work function metal is changed to oxide or nitride in the process of forming the metal layer 15, and the deterioration has already started from the beginning of element formation. Therefore, in the conventional device, the emission brightness was lower than the theoretical value.

However, in the present embodiment,
Since the metal layer 15 is formed on the electron-deficient material layer 16, the deterioration of the low work function metal can be prevented. More details are as follows. The low work function metal emits electrons even during the film forming process to become cations. The emitted electrons are accepted by the electron-deficient substance, so that anions of the electron-deficient substance are generated. This anion exchanges electrons with the cation before the cation reacts with water, oxygen, etc. to change into an oxide, etc., and as a result, charge transfer occurs. As a result, the low work function metal returns to the ground state, so that the low work function metal is suppressed from changing to an oxide or the like and deteriorating. As a result, the metal layer 15 containing very little oxide or the like can be formed, and high-luminance light emission of the device is enabled.

Further, as described above, since the deterioration of the low work function metal can be prevented, the layer thickness of the metal layer 15 can be further reduced. As a result, workability is improved. In addition, since it is possible to suppress variations in the emission brightness within the plane,
It is possible to manufacture the device with good reproducibility and improve the yield.

As described above, the thin film EL according to the first embodiment
According to the device manufacturing method, it is possible to manufacture a thin film EL device having extremely high emission brightness as compared with the conventional thin film EL device with good workability and reproducibility.

Here, when the thin film EL element has a pn junction, the thin film EL element has an electromotive force.
Electrons are exchanged in the device even when the device is not energized. Therefore, it can be considered that the reactions of the above reaction formulas (3) to (5) are proceeding even in the unloaded storage state. Furthermore, the reactions of the reaction formulas (3) to (5) also occur in the manufacturing process of the thin film EL device having the pn junction. Therefore, even in this case, a thin film EL element having high emission brightness can be manufactured with good workability and reproducibility and with improved yield.

In this embodiment, the case where the electron injection electrode 14 is composed of the metal layer 15 containing an alloy and the electron deficient material layer 16 has been described as an example, but the present invention is not limited to this. Not something. For example, as shown in FIG. 2, the electron injection electrode 14 includes an electron-deficient substance layer 16, a low work function metal layer 17 containing a low work function metal, in this order from the functional layer 13 side.
It may be a laminated electrode body in which a protective metal layer 18 containing a metal having a work function larger than that of the low work function metal is laminated. In this case, the low work function metal layer 17 and the protective metal layer 1
The film of 8 can be formed by a vapor deposition method, a sputtering method, or the like.

As shown in FIG. 3, the electron injection electrode 14
May be a laminated electrode body in which the electron-deficient substance layer 16 containing the low work function metal 21 and the protective metal layer 18 are laminated in this order from the functional layer 13 side. In this case, the electron-deficient material layer 16
The layer thickness is preferably in the range of 0.1 to 1000 nm. When the electron-deficient substance layer 16 is in the form of a monolayer having a substantially uniform layer thickness, the layer thickness is about 0.1 nm or more, depending on the type of electron-deficient substance and the content of the electron-deficient substance. That is, it is difficult to form the electron-deficient substance layer 16 having a smaller thickness than that. On the other hand, the layer thickness is 1
If it is larger than 000 nm, the applied voltage rises and the element is deteriorated, which is not preferable. Further, the content concentration of the electron-deficient substance may be in the range of 30 to 99 mol%. Thirty
When it is at most mol%, the electron transporting property cannot be sufficiently improved and deterioration of the low work function metal cannot be prevented, which is not preferable. On the other hand, when it is 99 mol% or more, the ratio of the low work function metal is relatively decreased, and the electron injection amount is decreased, which is not preferable. The electron-deficient substance layer 16 can be formed by co-evaporation of the electron-deficient substance and a low work function metal. The protective metal layer 18 can be formed by the vapor deposition method, the sputtering method, or the like as described above.

Further, as shown in FIG. 4, the electron injection electrode 1
4 may be a single layer containing an electron-deficient substance 20, a low work function metal 21, and a metal having a work function higher than that of the low work function metal 21. As a film forming method of the electron injection electrode 14 in this case, co-evaporation can be adopted.

In the present embodiment, the case where the electron-deficient substance layer 16 is in the form of a layer has been described as an example.
The present invention is not limited to this. For example,
In the thin film EL element shown in FIG. 1, the functional layer 13 and
It can be provided between the metal layer 15 and the metal layer 15. Further, in the thin film EL element shown in FIG. 2, the thin film EL element can be provided in an island shape between the functional layer 13 and the low work function metal layer 17.
Even with these configurations, it is possible to suppress deterioration of the low work function metal and improve the light emission life of the device.

(Embodiment 2) Another embodiment of the thin film EL element according to the present invention will be described below. The constituent elements having the same functions as the constituent elements in the thin film EL element of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The thin-film EL device according to the second embodiment is different from the thin-film EL device according to the first embodiment in that the electron-deficient substance is contained in the functional layer instead of the electron-injecting electrode.

FIG. 5A is a cross-sectional view schematically showing the thin film EL element according to the second embodiment, showing a state in which an electron-deficient substance is distributed in the functional layer. The electron injection electrode 22 shown in FIG.
It is a metal layer containing an alloy composed of more than one kind of metal. or,
The functional layer 23 basically has the same function as the functional layer according to the first embodiment, but in the present embodiment, the electron-deficient substance 20 is further contained. The electron-deficient substance 20 is provided so as to be distributed on the electron injection electrode 22 side in the functional layer 23. From the interface between the electron injection electrode 22 and the functional layer 23, the existence range of the electron-deficient substance 20 is
It can be set within a range of about 2/3 of the layer thickness of the functional layer 23. Here, the layer thickness of the functional layer 23 is, for example, 50 to 1000 nm. The electron-deficient substance 20 may be evenly distributed throughout the functional layer 23.

Here, for example, when the functional layer is formed by laminating the hole transport layer, the light emitting layer and the electron transport layer in this order from the hole injection electrode side, the electron deficient substance 20 is at least the electron transport layer. Included in. In this electron transport layer,
Anions (radicals) molecules are continuously generated by the transfer of electrons between adjacent molecules, and the electrons hop through the layer. By the way, a commonly used electron transport material has high stability in the ground state, and therefore, even if it accepts an electron and becomes an anion (radical) state, it immediately returns to the ground state. That is, the reverse reaction of releasing electrons is likely to occur. On the other hand, the anion generated from the electron-deficient substance can satisfy the octet rule by further accepting an electron, so that a forward reaction is likely to occur. As a result, it can continue to exist stably in the anion state. As can be seen from this, the electron-deficient substance has an excellent electron-transporting property, so that the functional layer 23
The transport of electrons to is good. As a result, the device can emit light with high brightness, and the luminous efficiency can be improved.

Further, the electron-deficient substance 20 is shown in FIG.
As shown in FIG. 4, the concentration can be increased as it gets closer to the electron injection electrode 22. Anion of electron-deficient substance (A
-) And a cation of a low work function metal react with each other in the functional layer 2
3 frequently occurs at the interface between the electron injection electrode 22 and the electron injection electrode 22. Some cations are ablated to form the functional layer 23.
Although it penetrates into the inside of the functional layer 23, the amount thereof decreases toward the inside of the functional layer 23, so that the frequency of the reaction between the electron-deficient substance anion and the cation also decreases. Therefore, if a concentration gradient is provided as in the above structure, it is possible to efficiently donate electrons to cations of a low work function metal.

The content concentration of the electron-deficient substance 20 is preferably in the range of 0.1 mol% or more and 99.9 mol% or less. If the content concentration is less than 0.1 mol%, the electron transporting property cannot be improved. On the other hand, if the content concentration is higher than 99.9 mol%, the functional layer 23 will not sufficiently fulfill the light emitting function as a result of being as close as possible to a single layer made of an electron-deficient substance. Further, when the electron-deficient substance 20 is uniformly distributed within a predetermined range from the interface between the functional layer 23 and the electron injection electrode 22, or when it is uniformly distributed throughout the functional layer 23. The concentration of the electron-deficient substance 20 is more preferably within the range of 0.1 mol% or more and 50.0 mol% or less.

Functional layer 2 in which the electron-deficient substance 20 is distributed
The film formation of No. 3 is performed as follows. First, the portion of the functional layer 23 not containing the electron-deficient substance 20 is treated as the hole injection electrode 1
It is formed on the surface 2 by a vapor deposition method. Next, the electron-deficient substance and the functional layer material are co-deposited by controlling the vapor deposition rate so as to have a predetermined mixing ratio. As a result, the electron-deficient substance 20
It is possible to form the functional layer 23 having a uniform distribution within the predetermined range on the electron injection electrode 22 side. On the other hand, when forming the functional layer 23 in which the electron-deficient substance 20 is distributed at a higher concentration as it gets closer to the electron injection electrode 22, it should be formed by raising the vapor deposition temperature (specifically, increasing the amount of current). You can

The functional layer 23 may contain a low work function metal 21 as well as the electron-deficient substance 20, as shown in FIG. In this case, the low work function metal 21 can be distributed in a higher concentration as it approaches the electron injection electrode 22. Here, the content of the low work function metal 21 is 0.0
It can be in the range of 1% by weight or more and 99.9% by weight or less. When the content is less than 0.01% by weight, the electron injecting ability is lowered and the luminous efficiency is reduced, which is not preferable. On the other hand, if the content is greater than 99.9% by weight,
As a result of approaching a single layer consisting of a low work function metal infinitely,
The functional layer 23 does not perform a sufficient light emitting function.

Further, the electron injection electrode 22 is the functional layer 2
It may be a laminated electrode body in which a low work function metal layer containing a low work function metal and a protective metal layer containing a metal having a work function larger than that of the low work function metal are laminated in order from the 3 side.

(Embodiment 3) Still another embodiment of the thin film EL element according to the present invention will be described below.
The constituent elements having the same functions as the constituent elements in the thin film EL element of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The thin-film EL device according to the third embodiment is different from the thin-film EL device according to the first embodiment in that an electron-deficient substance layer containing an electron-deficient substance is replaced with a trapping layer containing a trapping substance. Is different. The details are as follows.

FIG. 7 is a schematic sectional view showing a thin film EL element according to the third preferred embodiment. As shown in the figure, the thin film EL element 30 according to the present embodiment has at least a hole injecting electrode 12, an electron injecting electrode 31 forming a pair with the hole injecting electrode 12, and a hole injecting electrode on a substrate 11. This is a configuration in which a functional layer 13 provided between the injection electrode 12 and the electron injection electrode 31 is laminated.

The electron injection electrode 31 has a metal layer 15 and
The trapping layer 32 contains a trapping substance, and has a basic function of injecting electrons into the functional layer 13.

The trapping layer 32 contains at least a trapping substance. The trapping substance is a substance capable of forming a coordinate bond by donating an unshared electron pair possessed by the trapping substance to a cation having a low work function metal to share an electron pair.

Atoms constituting the trapping substance and belonging to the unshared electron pair include oxygen, sulfur, selenium, nitrogen, phosphorus and arsenic.

Further, it may be a heterocyclic compound containing these atoms. In this case, examples of the hetero atom of the heterocycle include oxygen, sulfur, nitrogen, arsenic and the like. Further, the trapping substance may be a compound having a functional group such as a carbonyl group, an amino group, an imino group and a thiocarbonyl group. Further, a chelating agent such as 1,10-phenanthroline having two or more of these functional groups and capable of multidentately coordinating ions of a low work function metal may be used.

In particular, an electron-accepting trapping substance that accepts an electron is most preferable, and as such an electron-accepting trapping substance, a compound represented by the following chemical formula (2) can be mentioned.

[0170]

[Chemical 10]

Here, R ⁷ and R ⁸ are a bridging ligand having a nitrogen-containing aromatic ring having at least one nitrogen atom as a coordinating atom or a ring derivative thereof, or a halogen atom or an alkyl group having 1 to 3 carbon atoms. bridging ligand der with
The nitrogen in the nitrogen-containing aromatic ring serves as a coordination atom . In the bridging ligand having a nitrogen-containing aromatic ring containing at least one nitrogen atom, examples of the bridging ligand having a nitrogen-containing aromatic ring containing one nitrogen atom include pyrrole, pyridine, oxazole and 3 , 3'-bipyridine-
5,5'-diyl etc. can be illustrated. Further, as a bridging ligand having a nitrogen-containing aromatic ring containing two or more nitrogen atoms, imidazole, pyrazole, pyridazine, pyrazine, pyrimidine, phthalazine, 1H-indazole, oxadiazole, 9,10-phenanthroline, triazole,
Examples include triazine, tetrazine, and tetrazole. Further, as the halogen, F, Cl, Br, I,
At can be exemplified. Further, examples of the bridging ligand having an alkyl having 1 to 3 carbon atoms include methyl, ethyl and butyl.

Further, each of R ⁹ , R ¹⁰ , R ¹¹ and R ¹² is any one selected from the group consisting of hydrogen, alkyl, aryl derivatives and heterocyclic derivatives, and R ⁹ to
At least one of R ¹² is a ligand having an unshared electron pair. Examples of the alkyl include methyl and ethyl. The aryl derivative may be phenyl, tolyl, pyridyl, triazole, tetrazole,
Examples thereof include indazole. Further, as the heterocyclic derivative, pyrrole, pyridine, oxazole, 3,
3'-bipyridine-5,5'-diyl, imidazole,
Pyrazole, pyridazine, pyrazine, pyrimidine, phthalazine, 1H-indazole, oxadiazole, 9,
10-phenanthroline, triazole, triazine,
Examples thereof include derivatives such as tetrazine and tetrazole.

Further, M ² is Be, Mg, Ca, B,
It is any one metal element or metalloid element selected from the atomic group consisting of Al and Ga.

Specific examples of the compound represented by the chemical formula (2) include 4,4,8, and
An example is 8-tetrakis (1H-pyrazol-1-yl) pyrazabol (hereinafter abbreviated as PPZB).

[0175]

[Chemical 11]

The portion shown in the wavy line of the chemical formula (6) shows the pyrazaball structure. This pyrazabol structure is a cyclic structure in which two bridging ligands (pyrazole) are each connected to two borons by a bridge bond. Since the number of electrons is insufficient in this cross-linking part, PP
ZB is also a kind of electron-deficient substance. Therefore, PPZB
Has an electron accepting property.

The technical significance of providing the trapping layer 32 containing the trapping substance as described above on the electron injecting electrode 14 is as described below.

The mechanism of suppressing deterioration of the low work function metal will be described by taking PPZB as the trapping substance and Li as the low work function metal as an example. As described in the first embodiment, Li contained in the electron injection electrode 14 emits electrons to become Li cations (see the reaction formula (3)).

PPZB donates an unshared electron pair to the Li cation, and as shown in the following chemical formula (7),
A new ring structure (chelate ring) is formed by being coordinated so as to sandwich Li (cation). The chelate complex thus produced has a highly stable structure due to its steric effect.

[0180]

[Chemical 12]

Therefore, by providing the trapping layer 32,
It is possible to prevent a low work function metal such as Li from becoming an insulator such as an oxide or a nitride, and stably supply electrons to the functional layer 13. As a result, the life of the device can be extended while realizing high-luminance light emission.

Since PPZB is also an electron-deficient substance, it has an excellent electron-transporting property, and as a result, it is possible to inject more electrons into the light-emitting layer.

The average layer thickness of the trapping layer 32 is 0.1 to 1
It is preferably within the range of 00 nm. When the trapping layer 32 is a monomolecular layer having a substantially uniform layer thickness, the layer thickness is about 0.1 nm or more depending on the type of trapping substance, and the trapping layer 32 having a thinner layer thickness can be formed. Because it is difficult. On the other hand, if the layer thickness is greater than 100 nm,
This is not preferable because the applied voltage rises and the element deteriorates.

Next, a method of manufacturing the thin film EL element according to the second embodiment will be described. First, the first embodiment
Similarly to the above, after forming the hole injection electrode 12 on the substrate 11, the functional layer 13 is formed on the electron injection electrode 14.

Next, the trapping layer 32 is formed on the functional layer 13 by the vacuum vapor deposition method. The vapor deposition conditions are not particularly limited and may be appropriately set so that a desired film structure is formed. Specifically, for example, the deposition rate is 0.01 to
If the vapor deposition is performed under the conditions of 0.5 nm / sec and a vacuum pressure of 10 ³ to 10 ⁶ Pa, the trapping layer 32 having a good film structure can be formed.

Next, the metal layer 15 is formed on the trapping layer 32 by, for example, the vapor deposition method or the sputtering method. Here, the low work function metal is changed to oxide or nitride in the process of forming the metal layer 15, and the deterioration has already started from the beginning of element formation. Therefore, in the conventional device, the emission brightness was lower than the theoretical value.

However, in the present embodiment,
Since the metal layer 15 is formed on the trapping layer 32, deterioration of the low work function metal can be prevented. More details are as follows. The low work function metal also emits electrons to become cations during the film formation process. This metal cation reacts with water, oxygen, etc. to form an oxide or a nitride,
Captured by the capture substance. Thereby, the metal of the low work function metal can be prevented from being deteriorated and the metal layer 15 can be formed, which enables high-luminance light emission.

Further, in order to prevent the deterioration of the low work function metal, the thickness of the metal layer 15 can be further reduced, whereby the workability can be improved. In addition, since it is possible to suppress variations in the light emission luminance within the plane, it is possible to manufacture the device with good reproducibility and improve the yield.

As described above, the thin film EL according to the second embodiment
According to the device manufacturing method, it is possible to manufacture a thin film EL device having extremely high emission brightness as compared with the conventional thin film EL device with good workability and reproducibility.

In the present embodiment, the case where the electron injection electrode 31 is composed of the metal layer 15 containing an alloy and the trapping layer 32 has been described as an example, but the present invention is not limited to this. is not. For example, as shown in FIG. 8, the electron injection electrode 14 may be a laminated electrode body in which a trapping layer 32, a low work function metal layer 17, and a protective metal layer 18 are laminated in this order from the functional layer 13 side.

Further, as shown in FIG. 9, the electron injection electrode 31
May be a laminated electrode body in which the trapping layer 32 containing the low work function metal 21 and the protective metal layer 18 are laminated in this order from the functional layer 13 side. In this case, the capture layer 32 has a layer thickness of 0.1 to
It is preferably in the range of 1000 nm. Capture layer 3
When 2 is a monomolecular layer having a substantially uniform layer thickness, the layer thickness is about 0.1 nm or more, although it depends on the kind of the trapping substance. That is, it is difficult to form the trapping layer 32 having a smaller layer thickness. On the other hand, the layer thickness is 1000n
When it is larger than m, the applied voltage rises and the element is deteriorated, which is not preferable. Furthermore, the content concentration of the trapping substance is 30
It may be in the range of 99 mol%. If it is 30 mol% or less, the electron transporting property cannot be sufficiently improved,
It is not preferable because deterioration of the low work function metal cannot be prevented. On the other hand, if it is 99 mol% or more, the proportion of the low work function metal is relatively lowered and the electron injection amount is reduced, which is not preferable. Further, the capture layer 32 can be formed by co-evaporation of the capture substance and the low work function metal. The protective metal layer 18 can be formed by the vapor deposition method, the sputtering method, or the like as described above.

Further, as shown in FIG. 10, the electron injection electrode 31 may be a single layer containing a trapping substance 33, a low work function metal 21, and a metal having a work function larger than that of the low work function metal 21. As a film forming method of the electron injection electrode 31 in this case, co-evaporation can be adopted.

In the present embodiment, the case where the trapping layer 32 is in the form of a layer has been described as an example, but the present invention is not limited to this. For example, the acquisition layer 3
2 may be provided in an island shape between the metal layer 15 and the low work function metal layer 17. Even in such a mode, it is possible to suppress the deterioration of the low work function metal and improve the light emission life of the device.

(Embodiment 4) Still another embodiment of the thin film EL element according to the present invention will be described below.
The constituent elements having the same functions as the constituent elements in the thin film EL element of the third embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The thin film EL element according to the fourth embodiment is different from the thin film EL element according to the third embodiment in that the trapping substance is contained in the functional layer instead of the electron injecting electrode.

FIG. 11A is a cross-sectional view schematically showing the thin film EL element according to the fourth embodiment, showing the case where the trapping substance is uniformly distributed in the functional layer. The electron injection electrode 35 shown in the figure is a metal layer containing an alloy composed of at least two kinds of metals having different work functions.
Further, the functional layer 36 basically has the same function as the functional layer according to the first embodiment, but in the present embodiment, the trapping substance 33 is further contained. This capture substance 3
3 are provided so as to be distributed on the electron injection electrode 35 side in the functional layer 36. The existence range of the trapping substance 33 is from the interface between the functional layer 36 and the electron injection electrode 35 to the functional layer 3
It can be within a range of about 2/3 of 6. here,
The layer thickness of the functional layer 36 is, for example, 50 to 1000 nm. The trapping substance 33 may be evenly distributed throughout the functional layer 36.

Further, the trapping substance 33 can be distributed in a higher concentration as it gets closer to the electron injection electrode 35, as shown in FIG. The reaction between the trapping substance and the cation of the low work function metal frequently occurs at the interface between the functional layer 36 and the electron injection electrode 35. Some cations penetrate into the functional layer 36 by ablation, but the amount thereof decreases toward the inside of the functional layer 36, so that the frequency of the reaction between the trapping substance and the cation also decreases. Therefore, if a concentration gradient is provided as in the above structure, it is possible to efficiently donate electrons to cations of a low work function metal.

The content concentration of the trapping substance 33 is preferably in the range of 0.1 mol% or more and 99.9 mol% or less. If the content concentration is less than 0.1 mol%, the cation of the low work function metal cannot be sufficiently captured by coordination bond or the like. On the other hand, when the content concentration is higher than 99.9 mol%, the functional layer 36 does not sufficiently perform the light emitting function as a result of being as close as possible to the single layer made of the trapping substance. Furthermore, when the trapping substance 33 is evenly distributed within a predetermined range from the interface between the functional layer 36 and the electron injection electrode 35, or when it is evenly distributed throughout the functional layer 36,
The content concentration of the trapping substance 33 is 0.1 mol% or more, 50.0
More preferably, it is within the range of not more than mol%.

Note that the low work function metal 21 may be contained in the functional layer 36 in the same manner as the trapping substance 33, as shown in FIG. In this case, the low work function metal 21
Can be distributed in a higher concentration as it approaches the electron injection electrode 35. Here, the content of the low work function metal 21 is
It can be contained within the range of 0.01% by weight or more and 99.9% by weight or less. When the content is less than 0.01% by weight, the electron injecting ability is lowered and the luminous efficiency is reduced, which is not preferable. On the other hand, when the content is larger than 99.9% by weight, the functional layer 36 does not sufficiently fulfill the light emitting function as a result of being as close as possible to a single layer made of a low work function metal.

Further, the electron injecting electrode 35 is the functional layer 3
It may be a laminated electrode body in which a low work function metal layer and a protective metal layer are laminated in order from the 6 side.

The functional layer 36 in which the trapping substance 33 is distributed is formed by the same method as described in the second embodiment. That is, a portion of the functional layer 36 that does not contain the trapping substance 33 is previously formed on the hole injection electrode 12 by the vapor deposition method. Then, the trapping substance and the functional layer material are co-deposited by controlling the vapor deposition rate so as to have a predetermined mixing ratio, whereby the trapping substance 33 is uniformly distributed within the predetermined range on the electron injection electrode 35 side. Form layer 36. On the other hand, when forming the functional layer 36 in which the trapping substance 33 is distributed in a higher concentration as it gets closer to the electron injection electrode 35, it is formed by raising the vapor deposition temperature (specifically, increasing the amount of current).

(Embodiment 5) Another embodiment of the thin film EL element according to the present invention will be described below. The constituent elements having the same functions as the constituent elements in the thin film EL element of each of the above-described embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

The thin film EL element according to the fifth embodiment is different from the thin film EL elements according to the above-described first embodiments in that both an electron-deficient substance and a trapping substance are used. The details are as follows.

FIG. 13 shows a thin film EL according to the fifth embodiment.
It is a cross-sectional schematic diagram which shows an element. As shown in the figure, the thin film EL element 40 according to the present embodiment has at least a hole injection electrode 12, an electron injection electrode 41 paired with the hole injection electrode 12, and a hole injection electrode 12 on a substrate 11. This is a configuration in which the functional layer 13 provided between the injection electrode 12 and the electron injection electrode 41 is laminated.

The electron injection electrode 41 includes the electron-deficient substance layer 16, the trapping layer 32, and the metal layer 1 in order from the functional layer 13 side.
5 is laminated to form a laminated electrode body. Since the electron-deficient material layer 16 has an excellent electron-transporting property, more electrons are injected into the functional layer 13, thereby increasing the recombination rate of holes and electrons and improving the light emission efficiency. On the other hand, the trapping layer 32 traps the low work function metal before it changes to an oxide or the like, and prevents the deterioration of the low work function metal. Therefore, by providing the electron-deficient substance layer 16 and the trapping layer 32 in the same element, it is possible to improve the light emission life and achieve high-luminance light emission.

The electron injection electrode 41 is formed of the metal layer 15
Instead of this, a laminated electrode body in which the low work function metal layer and the protective metal layer 18 are laminated in this order from the capturing layer 32 side may be used.

Further, as shown in FIG. 14, the electron injecting electrode 41 comprises the electron deficient material layer 16,
It may be a laminated electrode body in which the low work function metal layer 22 containing the trapping substance 33 and the protective metal layer 18 are laminated.

The electron injecting electrode 41 contains an electron-deficient substance and a trapping substance in the same layer, and the metal layer 15 is laminated on this layer, or a low work function metal layer and a protective metal layer are formed. It may be laminated.

Since the electron-deficient substance has an excellent electron-transporting property and the trapping substance is effective for trapping the low work function metal,
The trapping layer 32 is advantageously provided on the side of the metal layer 15 containing the low work function metal or the low work function metal layer 22. However, diffusion of cations of a low work function metal into the functional layer 13 may deactivate the excited state of the light emitting material in the functional layer 13. Therefore, from the viewpoint of preventing this, the electron injection electrode 41
In the case of forming the
2 / electron-deficient substance layer 16 / metal layer 15 may be laminated. Alternatively, the trapping layer 32 / electron-deficient substance layer 16 / low work function metal layer 22 / protective metal layer 18 in order from the functional layer 13 side.
May be laminated.

(Embodiment 6) Still another embodiment of the thin film EL element according to the present invention will be described below.
The constituent elements having the same functions as the constituent elements in the thin film EL element of the third embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the thin film EL element according to the sixth embodiment, as compared with the thin film EL element according to the third embodiment, the electron deficient substance and / or the trapping substance are contained in the functional layer instead of the electron injecting electrode. The points are different.

More specifically, for example, as shown in FIG. 15A, a metal layer is formed on the functional layer 51 provided so that the electron-deficient substance 20 and the trapping substance 33 are distributed on the electron injection electrode 31 side. An electron injection electrode made of 15 may be laminated.

Further, as shown in FIG. 13B, the metal layer 15 may be replaced with a low work function metal layer 17 and a protective metal layer 18 which are laminated in this order from the functional layer 51 side.

Furthermore, the electron-deficient substance 20 or the trapping substance 33
One of the above may be included in the functional layer, and the other may include the electron injecting electrode.

(Other Matters) In each of the above embodiments, the mode in which the hole injecting electrode, the functional layer and the electron injecting electrode are sequentially provided on the substrate has been described, but the present invention is not limited to this. It is not limited. For example, it may be an element in which an electron injection electrode, a functional layer, and a hole injection electrode are sequentially laminated on a substrate.

Furthermore, in each of the above-mentioned embodiments, the thin film EL element in which surface emission is performed from the substrate side has been described as an example, but it is also possible to take out light from the electron injecting electrode side. In the present invention, for example, as described in the first, third or fifth embodiment, for example, the electron deficient substance layer and / or the trapping layer are provided on the functional layer, so that the low work function is obtained. It is possible to reduce damage to the functional layer when forming a metal layer or the like. To reduce the damage to the functional layer, it is possible to form a transparent or semitransparent conductive film in place of the protective metal layer made of Al or the like. Here, as the transparent or translucent conductive film, ITO, Au, or Mg-A is used.
An alloy thin film such as a g-alloy or an Ag-Pd-Cu alloy may be used. As a result, the following new effects can be achieved. That is, when light is obtained through a transparent substrate such as a glass substrate, not all of the light emitted from the functional layer is transmitted through the substrate, but a part of the light is lost by total reflection inside the substrate. . However, with the above configuration, light can be extracted without passing through the substrate, so that light loss can be reduced and the light extraction efficiency can be significantly improved. In this case, the visible light transmittance of the electron injecting electrode is preferably 50% or more, and further 7
It is more preferably 0% or more.

Further, in each of the above-mentioned embodiments, the direct current driving type thin film EL element has been described as an example, but the present invention is not limited to this. For example, an AC drive type or a pulse drive type may be used.

Further, the electrode having the electron-deficient substance and / or the trapping substance according to the present invention may be a biosensor or a photoelectric conversion device (for example, a photocell or a photosensor) in addition to the thin film EL device.
It is also applicable to.

[0219]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The following Examples 1 to 3 relate to thin film EL devices using an electron-deficient substance.
Example 7 relates to a thin film EL element using a trapping substance, and Examples 8 to 10 relate to a thin film EL element using an electron deficient substance and a trapping substance.

(Example 1) First, an ITO (Indium Tin Oxide) film (hole injection electrode) was formed on a glass substrate by a sputtering method. Next, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine was used as a hole transport layer material, and the ITO was deposited by a vapor deposition method. A hole transport layer was formed on the film. The thickness of the hole transport layer was 50 nm.

Subsequently, as an organic light emitting layer material, tris (8
-Quinolinolato) aluminum was used to form an organic light emitting layer (light emitting layer) on the hole transport layer by a vapor deposition method. The layer thickness of the organic light emitting layer was 50 nm. Further, 4,4,8,8-tetraphenylpyrazaball was used as the electron-deficient substance, and an electron-deficient substance layer was formed on the organic light emitting layer by a vapor deposition method. The layer thickness of the electron-deficient substance layer was 1 nm.

Next, a Li film (low work function metal layer) having a layer thickness of 0.5 nm was formed on the electron-deficient substance layer by a vapor deposition method. Further, an Al film (protective metal layer) having a layer thickness of 100 nm was formed on the Li film. Thereby, the thin film EL device of the present invention was produced.

A power source was connected to the ITO film and the Al film of this thin film EL device, and a direct current voltage was applied to measure the light emitting characteristics. As a result, the brightness (luminance) is about 50 when applying about 4V.
It was 0 cd / m ² and the luminous efficiency was 5.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 700 hours at 00 cd / m ² . The above results are shown in Table 1 below.

[0225] Also, 100 thin film EL elements of the above 10
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 2) The thin-film EL device according to the second embodiment contains an electron-deficient substance instead of the electron-deficient substance layer as compared with the thin-film EL device according to the first embodiment. The difference is that a light emitting layer is provided.

The organic light emitting layer according to the second embodiment was formed as follows. That is, tris (8-
(Quinolinolato) aluminum, and a layer made of an organic light emitting material alone (layer thickness: 40 n) on the hole transport layer by vapor deposition.
m) was formed. Then Tris (8-quinolinolato)
Aluminum and 4, 4, 8, 8 as electron-deficient substances
A layer in which an electron-deficient substance is uniformly distributed in the organic light-emitting material (layer thickness: 10) by co-evaporation with tetraphenylpyrazaball.
nm). Thereby, the organic light emitting layer (light emitting layer,
Layer thickness 50 nm) was formed. The weight ratio of the organic light emitting layer material to the electron-deficient material was set to 9: 1.

Further, with respect to the thin film EL element according to the second embodiment, the light emission characteristics were examined in the same manner as in the first embodiment, and the luminance (luminance) was about 500 cd / m when an applied voltage was about 4V.
² , and the luminous efficiency was 5.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 700 hours at 00 cd / m ² . The above results are shown in Table 1 below.

[0230] Also, the above thin film EL device is 100 pieces x 10
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 3) The thin film EL element according to the present embodiment 3 is different from the thin film EL element according to the embodiment 1 in L
The difference is that the i-layer contains an electron-deficient substance.

Here, the electron-deficient substance layer according to Example 3 was formed on the organic light-emitting layer by co-evaporation so that the molar ratio of Li to the electron-deficient substance was 1: 1. Further, with respect to the thin film EL element according to the present Example 2, the light emission characteristics were examined in the same manner as in the above Example 1, and it was found that the luminance (luminance) was about 500 cd / m ² when an applied voltage was about 4 V, and the light emission efficiency was It was 5.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 700 hours at 00 cd / m ² . The above results are shown in Table 1 below.

In addition, 100 thin film EL elements are prepared in a number of 10
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 4) The thin film EL element according to the present embodiment 4 is different from the thin film EL element according to the above embodiment 1 in that a trapping layer is provided instead of the electron-deficient substance layer.

Here, in the trapping layer according to Example 4, electron-accepting 4,4,8,8-tetrakis (1H-pyrazol-1-yl) pyrazaball was used as a trapping substance,
It was formed on the organic light emitting layer by a vapor deposition method. The thickness of the trapping layer was 1 nm.

Further, the light emitting characteristics of the thin film EL device according to the fourth embodiment were examined in the same manner as in the first embodiment. The brightness (luminance) was about 500 cd / m when an applied voltage was about 4V.
² , and the luminous efficiency was 6.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 700 hours at 00 cd / m ² . The above results are shown in Table 1 below.

In addition, 100 thin film EL elements described above × 10
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 5) The thin film EL element according to the present embodiment 5 is different from the thin film EL element according to the embodiment 4 in that the layer thickness of the trapping layer is changed from 1 nm to 2 nm.

Further, the light emitting characteristics of the thin film EL element according to the fourth embodiment were examined in the same manner as in the first embodiment. The brightness (luminance) was about 600 cd / m when an applied voltage of about 4V.
² , and the luminous efficiency was 6.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 1000 hours at 00 cd / m ² . The above results are shown in Table 1 below.

Also, the thin film EL element is 100 × 10.
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 6) Compared with the thin film EL element according to the fifth embodiment, the thin film EL element according to the sixth embodiment has an organic light emitting layer containing a trapping material instead of providing the trapping layer. Is different.

The organic light emitting layer according to Example 6 was formed as follows. That is, tris (8-
(Quinolinolato) aluminum, and a layer made of an organic light emitting material alone (layer thickness: 40 n) on the hole transport layer by vapor deposition.
m) was formed. Then Tris (8-quinolinolato)
A layer in which aluminum and 4,4,8,8-tetrakis (1H-pyrazol-1-yl) pyrazaball as a trapping substance are co-deposited, and the trapping substance is uniformly distributed in the organic light emitting material (layer thickness: 10 nm). Was formed. As a result, an organic light emitting layer (light emitting layer, layer thickness 50 nm) was formed. The weight ratio of the organic light emitting layer material and the trapping substance material was set to 8: 2.

Further, with respect to the thin-film EL device according to the sixth embodiment, the light emission characteristics were examined in the same manner as in the first embodiment. The brightness (luminance) was about 600 cd / m when an applied voltage was about 4V.
² , and the luminous efficiency was 6.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 1000 hours at 00 cd / m ² . The above results are shown in Table 1 below.

Also, the thin film EL element is 100 × 10.
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 7) The thin film EL element according to the present embodiment 7 has an L value lower than that of the thin film EL element according to the embodiment 5.
The difference is that a capture substance is contained in the i layer.

Here, the electron-deficient substance layer according to Example 3 was formed on the organic light-emitting layer by co-evaporation so that the molar ratio of Li and the trapping substance was 1: 2.

Further, with respect to the thin-film EL device according to the second embodiment, the light emission characteristics were examined in the same manner as in the first embodiment. The luminance (luminance) was about 600 cd / m when an applied voltage was about 4V.
² , and the luminous efficiency was 6.0 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 1000 hours at 00 cd / m ² . The above results are shown in Table 1 below.

Also, the thin film EL element is 100 × 10.
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 8) The thin film EL element according to the present embodiment 8 is different from the thin film EL element according to the above embodiment 1 in that a trapping layer is provided on the electron-deficient substance layer. More specifically, a layer thickness of 10 nm is formed on the organic light emitting layer having a layer thickness of 30 nm.
The electron-deficient substance layer and the trapping layer having a layer thickness of 5 nm are sequentially provided. Further, in Example 8, Al was used as the anode.
Instead of the film, an ITO film having a layer thickness of 100 nm was formed.

Regarding the thin film EL device according to the eighth embodiment,
When the light emission characteristics were examined in the same manner as in Example 1, the brightness (luminance) was about 500 cd / m ² when an applied voltage was about 5 V, and the light emission efficiency was 5.5 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 1800 hours at 00 cd / m ² . The above results are shown in Table 1 below.

[0257] Also, 100 thin film EL elements of the above 10
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

(Embodiment 9) Compared with the thin film EL element according to the eighth embodiment, the thin film EL element according to the present embodiment 9 is an organic light emitting device containing an electron deficient substance instead of the electron deficient substance layer. The difference is that a layer (layer thickness 20 nm) is provided.

The organic light emitting layer according to Example 9 was formed as follows. That is, tris (8-
(Quinolinolato) aluminum is used to form a layer (layer thickness: 20 n) made of an organic light emitting material alone on the hole transport layer by vapor deposition.
m) was formed. Then Tris (8-quinolinolato)
Aluminum and 4, 4, 8, 8 as electron-deficient substances
A layer in which an electron-deficient substance is uniformly distributed in the organic light-emitting material (layer thickness: 20) by co-evaporation with tetraphenylpyrazaball.
nm). Thereby, the organic light emitting layer (light emitting layer,
(Layer thickness 40 nm). The weight ratio of the organic light emitting layer material to the electron-deficient material was set to 1: 1.

Further, with respect to the thin film EL element according to the present Example 9, the light emission characteristics were examined in the same manner as in the Example 1, and the luminance (luminance) was about 500 cd / m when an applied voltage was about 5V.
² , and the luminous efficiency was 5.5 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 1800 hours at 00 cd / m ² . The above results are shown in Table 1 below.

Also, the thin film EL element is 100 × 10.
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

Example 10 Thin Film E According to Example 10
The L element is different from the thin film EL element according to Example 8 in that the Li film contains a trapping substance.

Here, the trapping layer according to Example 10 was formed on the electron-deficient substance layer by co-evaporation so that the molar ratio of the trapping substance material to Li was 1: 2.

Further, the light emitting characteristics of the thin film EL element according to the tenth embodiment were examined in the same manner as in the first embodiment.
m ² , and the luminous efficiency was 5.5 cd / A.

Further, a constant current continuous lighting test was conducted on the thin film EL element according to this example. As a result, the initial brightness is 3
The luminance half-life was about 1800 hours at 00 cd / m ² . The above results are shown in Table 1 below.

In addition, 100 thin film EL elements are formed in a number of 10
A display device having 0 pieces arranged in a matrix was manufactured. When a moving image was displayed on this display device, it was confirmed that a good image was obtained.

Comparative Example 1 The comparative thin film EL element according to Comparative Example 1 is different from the thin film EL element according to Example 1 in that it does not have an electron-deficient substance layer.

The emission characteristics of this comparative thin film EL element were measured in the same manner as in Example 1 above.
The luminance was about 300 cd / m ² and the luminous efficiency was 3.5 cd / A.

Further, a constant current continuous lighting test was also conducted, and it was found that the initial luminance was 300 cd / m ² and the luminance half-life was about 10
It was 0 hours. The above results are shown in Table 1 below.

(Comparative Example 2) The comparative thin film EL element according to Comparative Example 1 is different from the thin film EL element according to Example 1 in that a Li film is not provided.

The emission characteristics of this comparative thin film EL device were measured in the same manner as in Example 1 above, and it was found to be about 4V.
The luminance was about 500 cd / m ² and the luminous efficiency was 4.5 cd / A.

Furthermore, a constant current continuous lighting test was also conducted, and it was found that the initial luminance was 300 cd / m ² and the luminance half-life was about 55.
It was 0 hours. The above results are shown in Table 1 below.

(Results) As is clear from Table 1 below, the thin film EL device of the present invention containing an electron-deficient substance and / or a trapping substance has higher luminous efficiency and excellent light emitting characteristics than the comparative thin film EL device. I found out that It was also confirmed that the luminance half-life was long with respect to the initial luminance, and as a result, the reduction in life was suppressed.

[0275]

[Table 1]

[0276]

As described above, according to the thin film EL device of the present invention, the cations of the low work function metal can be captured, so that the deterioration of the low work function metal can be suppressed. As a result, the luminous efficiency of the device can be improved and the life characteristics can be dramatically improved.

Further, according to the method of manufacturing a thin film EL element according to the present invention, deterioration of the low work function metal that has occurred during the manufacturing process can be suppressed, workability and reproducibility are excellent, and yield can be improved. Thin film EL with high luminous efficiency and long light emission life
A device can be manufactured.

Further, according to the display device having the thin film EL element of the present invention, since the thin film EL element having high luminous efficiency, high reliability and long life is provided, it is possible to provide a high quality display device. You can

Further, according to the illuminating device equipped with the thin film EL element according to the present invention, since it has high emission efficiency, high reliability, and long-lifetime emission characteristics, for example, a backlight for a liquid crystal display or the like. It is possible to provide a high-quality lighting device applicable to the above.

As described above, according to the configuration of the present invention, each object of the present invention can be sufficiently achieved.
Therefore, the industrial significance of the present invention is great.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a thin film EL element according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing another thin film EL element according to the first embodiment of the present invention.

FIG. 3 is still another thin film EL according to the first embodiment of the present invention.
It is a cross-sectional schematic diagram which shows an element.

FIG. 4 is still another thin film EL according to the first embodiment of the present invention.
It is a cross-sectional schematic diagram which shows an element.

FIG. 5 is a schematic sectional view showing a thin film EL element according to a second embodiment of the present invention, wherein FIG. 5 (a) shows a state in which an electron-deficient substance is uniformly distributed in a functional layer, FIG. 6B shows a state in which the electron-deficient substance has a concentration gradient and is distributed in the functional layer.

FIG. 6 is a schematic sectional view showing another thin film EL element according to the second embodiment of the present invention.

FIG. 7 is a schematic sectional view showing a thin film EL element according to a third embodiment of the present invention.

FIG. 8 is a schematic sectional view showing another thin film EL element according to the third embodiment of the present invention.

FIG. 9 is still another thin film EL according to the third embodiment of the present invention.
It is a cross-sectional schematic diagram which shows an element.

FIG. 10 is still another thin film E according to the third embodiment of the present invention.
It is a cross-sectional schematic diagram which shows an L element.

FIG. 11 is a schematic cross-sectional view showing a thin film EL element according to Embodiment 4 of the present invention, in which FIG. 11 (a) shows a state in which a trapping substance is uniformly distributed in a functional layer. (B) shows a state in which the trapping substance has a concentration gradient and is distributed in the functional layer.

FIG. 12 is a schematic sectional view showing another thin film EL element according to Embodiment 4 of the present invention.

FIG. 13 is a schematic sectional view showing a thin film EL element according to a fifth embodiment of the present invention.

FIG. 14 is a schematic sectional view showing another thin film EL element according to Embodiment 5 of the present invention.

FIG. 15 is a schematic sectional view showing a thin film EL element according to a sixth embodiment of the present invention.

FIG. 16 is a schematic sectional view showing a conventional thin film EL element.

FIG. 17 is a schematic sectional view showing another conventional thin film EL element.

[Explanation of symbols]

10, 30, 40 Thin film EL device 11 board 12 Hole injection electrode 13,23,36,51 Functional layer 14 Electron injection electrode 15 Metal layer 16 Electron-deficient material layer 17 Low work function metal layer 18 Protective metal layer 20 electron-deficient substances 21 Low work function metal 22, 31, 35, 41 Electron injection electrode 32 capture layer 33 Captured substance

Continuation of the front page (56) References JP 2001-3044 (JP, A) JP 10-270171 (JP, A) JP 7-268317 (JP, A) JP 7-26255 (JP, A) A) JP 4-230997 (JP, A) JP 8-259939 (JP, A) JP 8-225579 (JP, A) JP 11-233262 (JP, A) JP 9 -316441 (JP, A) JP-A-11-121176 (JP, A) JP-A-11-121177 (JP, A) JP-A 8-31574 (JP, A) (58) Fields investigated (Int.Cl . ⁷ , DB name) H05B 33/00-33/28

Claims (13)

(57) [Claims] 1. An electron injection electrode containing at least two kinds of metals having different work functions, a hole injection electrode paired with the electron injection electrode, and provided between the electron injection electrode and the hole injection electrode. And a functional layer which emits light by an electric field applied by both electrodes, wherein the electron injection electrode contains a compound represented by the following chemical formula (1). [Chemical 1] (The R ¹ and R ² are a bridging ligand having a nitrogen-containing aromatic ring or a nitrogen-containing aromatic ring derivative having at least one nitrogen atom as a coordinating atom, and halogen or alkyl having 1 to 3 carbon atoms. The bridging ligand has any one selected from the group consisting of those having a nitrogen atom in a nitrogen-containing aromatic ring as a coordinating atom, R ³ , R ⁴ , R ⁵ and R
⁶ is any one selected from the group consisting of hydrogen, alkyl, aryl derivatives and heterocyclic derivatives.
The M ¹ is boron. ) 2. The thin film EL element according to claim 1, wherein the electron injecting electrode is provided on the functional layer and has a compound represented by the chemical formula (1), and a low work function metal. And a protective metal layer which is provided on the layer and which contains a metal having the largest work function. 3. The thin film E according to claim 1 or 2.
An L element, wherein the electron injection electrode is transparent or semitransparent. 4. The thin film EL element according to claim 3, wherein the visible light transmittance of the electron injection electrode is 50% or more. 5. The thin film E according to claim 3 or 4.
A thin film EL element, which is an L element, wherein the hole injection electrode is a reflective electrode which also serves as a reflective layer. 6. The thin film EL element according to claim 1, wherein the layer containing the compound represented by the chemical formula (1) and a low work function metal has a thickness of 0. A thin film EL device characterized by being in the range of 1 to 100 nm. 7. The thin film EL element according to claim 1, wherein the electron injecting electrode is provided on the functional layer, and includes a layer containing the compound represented by the chemical formula (1), A layer containing a low work function metal provided on a layer containing the compound represented by (1), and a protective metal containing a metal having the largest work function provided on the layer containing the low work function metal. A thin film EL element having a layer. 8. The thin-film EL device according to claim 7, wherein the layer containing the compound represented by the chemical formula (1) is provided in a layered or island-shaped manner within a thickness range of 0.1 to 100 nm. A thin film EL device characterized in that 9. An electron injection electrode, a hole injection electrode paired with the electron injection electrode, light emission by an electric field provided between the electron injection electrode and the hole injection electrode, and applied by both electrodes. A thin film EL device, wherein the functional layer contains a low work function metal having a work function smaller than that of the electron injection electrode, and a compound represented by the following chemical formula (1). . [Chemical 2] (The above-mentioned R ¹ and R ² are a bridging ligand having a nitrogen-containing aromatic ring or a nitrogen-containing aromatic ring derivative having at least one nitrogen atom as a coordinating atom, and halogen or alkyl having 1 to 3 carbon atoms. The bridging ligand has any one selected from the group consisting of those having a nitrogen atom in a nitrogen-containing aromatic ring as a coordinating atom, R ³ , R ⁴ , R ⁵ and R
⁶ is any one selected from the group consisting of hydrogen, alkyl, aryl derivatives and heterocyclic derivatives.
The M ¹ is boron. ) 10. The thin film EL device according to claim 9, wherein the low work function metal and the compound represented by the chemical formula (1) are uniformly contained within a predetermined range on the electron injection electrode side. A thin film EL device characterized in that 11. The thin film EL device according to claim 10, wherein the low work function metal and the compound represented by the chemical formula (1) are contained within a predetermined range on the electron injection electrode side. And a thin film EL device having a higher concentration toward the electron injection electrode. 12. A thin-film EL element according to any one of claims 2 to 11, wherein the work function of the low work function metal, a thin film EL device which is characterized in that not more than 4 eV. 13. The thin film EL element according to claim 12 , wherein the low work function metal is an alkali metal or an alkaline earth metal.