JP2004227943A - Organic electroluminescence element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element with a structure in which damage to an organic EL layer inflicted by the sputter at the time of formation of the upper electrode is suppressed and the work function of the upper electrode and ionization potential of the hole injecting layer can be made compatible. <P>SOLUTION: This organic EL element comprises a negative electrode, an organic EL layer, and an upper transparent positive electrode on a substrate, and the organic EL layer includes at least an organic luminous layer and a hole injecting layer, and the hole injecting layer makes contact with the upper transparent positive electrode, with the hole injecting layer having a thickness of 30-1,000 nm, and it emits light to the outside through the upper transparent positive electrode. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００６５】
表１から明らかなように、本発明にしたがう実施例１〜４の有機ＥＬ発光素子は、比較例１の素子よりも高い発光効率および低い発光開始電圧を示した。これは、上部透明陽極１形成のためのスパッタ時に、比較例１において発生した素子の正孔注入層１１のダメージおよび／または正孔注入層１１のイオン化ポテンシャルと上部透明電極１の仕事関数との不一致に起因すると考えられる。
【００６６】
また実施例３および４の素子は、それぞれ実施例１および２の素子よりも高い発光効率および低い発光開始電圧を示した。これは、正孔注入層１１表面へのイオン注入により、正孔注入層のイオン化ポテンシャルと上部透明陽極の仕事関数とが良好に一致したためと考えられる。
【００６７】
【発明の効果】
以上のように、本発明によれば、上部電極を陽極として、１）正孔注入層の膜厚を３０〜１０００ｎｍの範囲とすること、２）有機ＥＬ層と上部電極との間に正孔注入性保護層を設けること、および３）正孔注入層または正孔注入性保護層にイオン注入をすることの少なくとも１つにより、優れた発光効率および発光開始電圧を示す上部電極を通して外部へと発光するいわゆるトップエミッション方式の有機ＥＬ発光素子を得ることができた。
【図面の簡単な説明】
【図１】従来技術の有機ＥＬ発光素子を示す概略断面図である。
【図２】本発明の第１の実施形態の有機ＥＬ発光素子を示す概略断面図である。
【図３】本発明の第２の実施形態の有機ＥＬ発光素子を示す概略断面図である。
【図４】本発明の有機ＥＬ発光素子により形成される多色表示ディスプレイの一例を示す概略断面図である。
【符号の説明】
１ 上部透明陽極
２、１０２ 有機ＥＬ層
３ 陰極
１１、１１１ 正孔注入層
１２、１１２ 正孔輸送層
１３、１１３ 有機発光層
１４、１１４ 電子輸送層
１５、１１５ 電子注入層
１６ 正孔注入性保護層
２１ 基板
２２ スイッチング素子
２３ 透明基板
２４（Ｒ，Ｇ，Ｂ） 色変換カラーフィルタ層
２５ ブラックマスク
２６ 接着層
１０１ 陽極
１０３ 陰極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a structure of an organic EL light emitting device and a method for manufacturing the same. More specifically, the present invention relates to a structure of a hole injection layer and a method of manufacturing the same in a top emission type organic EL light emitting device.
[0002]
[Prior art]
In 1987, Eastman Kodak C.I. W. Since Tang et al. Announced a high-efficiency organic EL light emitting device having a two-layer structure (see Non-Patent Document 1), various organic EL light emitting devices have been developed to date, and some of them have begun to be put into practical use. I have. Under these circumstances, improving the luminous efficiency of the organic EL light emitting element is one of the extremely important tasks in practical use.
[0003]
On the other hand, in recent years, in an organic EL light emitting display, an active matrix drive type display has been actively developed. When the active matrix driving method is used, a plurality of organic EL elements are formed on a substrate provided with a thin film transistor (TFT) as a switching element, and the elements are used as a light source of a display. One of the problems of the active matrix drive type display at present is that the characteristics of individual TFTs and organic EL light-emitting elements vary greatly, and a complicated drive circuit is required to correct the variations. However, providing such a complicated drive circuit increases the number of TFTs required to drive one pixel.
[0004]
In a general organic EL device, a transparent electrode is provided on a glass substrate, an organic EL layer is provided thereon, and a reflective film and an electrode function are provided on the back surface in order to increase the amount of light taken out. It is common to employ a so-called bottom emission method in which an upper electrode having the same is formed using aluminum or silver and light is extracted from a glass surface. However, as described above, when the number of TFTs for driving one pixel increases, the area of the TFT that does not transmit light increases, and the area for extracting light decreases. In such a situation, a top emission method in which light is extracted from the upper electrode using the upper electrode as a transparent electrode is more advantageous, and development has been advanced (see Patent Documents 1 to 3).
[0005]
In a top emission type device, the upper electrode is generally a transparent cathode. FIG. 1 shows an example of a top emission type device. In this device, an organic EL layer 102 and a cathode 103 are stacked on an anode 101. The organic EL layer 102 includes at least an organic EL layer 113. In FIG. 1, the organic EL layer 102 includes a hole injection layer 111, a hole transport layer 112, an organic light emitting layer 113, an electron transport layer 114, and an electron injection layer 115. In this device, the cathode 103 is transparent, and light emitted from the organic EL layer 113 is extracted outside through the cathode 103.
[0006]
[Patent Document 1]
Patent No. 2689917
[0007]
[Patent Document 2]
Patent No. 3203227
[0008]
[Patent Document 3]
JP 2001-176660 A
[0009]
[Non-patent document 1]
C. W. Tang, S.M. A. VanSlyke, Appl. Phys. Lett. , 51, 913 (1987).
[0010]
[Non-patent document 2]
G. FIG. Parthasarathy, C.I. Adachi, P .; E. FIG. Burtows and S.M. R. Forrest, Appl. Phys. Lett. , 76 (15), 2128 (2000)
[0011]
[Problems to be solved by the invention]
One of the problems in the top emission type organic EL light-emitting device using the upper electrode as a cathode is damage to the electron injection layer 115 given when the cathode is formed. Conventional electron transport layers (eg, Alq ₃ In order to simultaneously provide transparency and electron injection, the electron injection layer 115 is made of an ultrathin film of an electron injection metal (thickness of 10 nm or less), and the cathode 103 is made of a transparent conductive oxide. It is necessary to Generally, the cathode 103 is formed by a sputtering method. The electron injection layer 115 is damaged by sputtered particles or oxygen plasma at the time of formation, and suffers from deterioration in device characteristics such as a decrease in luminous efficiency and an increase in luminescence start voltage. When the thickness of the electron injection layer 115 is increased to prevent this, the transparency of the electron injection layer decreases and the resistance value increases due to the low electron mobility of the material for the electron injection layer. Also, the luminous efficiency decreases and the luminescence starting voltage increases.
[0012]
To solve this problem, it has been studied to dope the electron injection layer 115 with an alkali metal such as Li or Cs, thereby improving the electron mobility and making the electron injection layer 115 thicker. (See Non-Patent Document 2). However, when the electron injection layer is doped with an alkali metal, there is a problem in terms of life.
[0013]
On the other hand, since the transparent conductive oxide has a large work function suitable for hole injection, it is conceivable to use an upper electrode formed of the transparent conductive oxide as an anode. However, in this case, the following problem occurs. An anode 101 serving as a lower electrode is formed by laminating a transparent conductive oxide having a large work function and applying UV irradiation or O 2 ₂ It is formed by performing a process such as a plasma process to adjust the surface work function to the ionization potential of the hole injection layer 111. However, when the anode is used as the upper electrode, this process cannot be performed. Therefore, a mismatch between the surface work function of the upper transparent electrode (anode) and the ionization potential of the hole injection layer occurs, and the light emission of the element occurs. This causes a decrease in efficiency and an increase in light emission starting voltage.
[0014]
Therefore, damage to the organic EL layer, which is caused by sputtering when forming the upper electrode, is suppressed, and the work function of the upper electrode and the ionization of the hole injection layer (specifically, the constituent layer of the organic EL layer in contact with the upper electrode). There is a strong demand for an organic EL device having a structure that can be adjusted to a potential and a method for manufacturing the same.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, the organic EL light emitting device according to the first embodiment of the present invention has a cathode, an organic EL layer, and an upper transparent anode on a substrate, and the organic EL layer has: At least an organic light emitting layer and a hole injection layer, wherein the hole injection layer is in contact with the upper transparent anode, has a thickness of 30 to 1000 nm, and emits light to the outside through the upper transparent anode. Features.
[0016]
The organic EL device according to the second embodiment of the present invention has a cathode, an organic EL layer, a hole-injecting protective layer, and an upper transparent anode on a substrate. It emits light.
[0017]
The organic EL light emitting device of the third embodiment of the present invention has a cathode, an organic EL layer, and an upper transparent anode on a substrate, and the organic EL layer includes an organic light emitting layer and a hole injection layer. At least, the hole injection layer is in contact with the upper transparent anode, is ion-implanted into a surface of the hole injection layer that contacts the upper transparent anode, and emits light to the outside through the upper transparent anode. And
[0018]
The organic EL light emitting device according to the fourth embodiment of the present invention has a cathode, an organic EL layer, a hole injecting protective layer, and an upper transparent anode on a substrate, wherein the hole injecting protective layer is And ion-implanting the surface of the hole-injecting protective layer that comes into contact with the upper transparent anode, and emitting light to the outside through the upper transparent anode.
[0019]
The fifth embodiment of the present invention is a method for manufacturing an organic EL light emitting device, in which a step of stacking a cathode on a substrate, a step of stacking an organic light emitting layer, and a hole injection having a thickness of 30 to 1000 nm are performed. It is characterized by including at least a step of laminating layers and a step of laminating an upper transparent anode. The step of laminating the upper transparent anode may be performed by a sputtering method.
[0020]
The sixth embodiment of the present invention is a method for manufacturing an organic EL light emitting device, which includes a step of laminating a cathode on a substrate, a step of laminating an organic light emitting layer, and a step of laminating a hole injection protective layer. And laminating an upper transparent anode. The step of laminating the upper transparent anode may be performed by a sputtering method.
[0021]
A seventh embodiment of the present invention is a method for manufacturing an organic EL light emitting device, wherein a step of stacking a cathode on a substrate, a step of stacking an organic light emitting layer, a step of stacking a hole injection layer, The method is characterized by including at least a step of implanting ions into the hole injection layer and a step of laminating the upper transparent anode. The step of laminating the upper transparent anode may be performed by a sputtering method.
[0022]
The eighth embodiment of the present invention is a method for manufacturing an organic EL light emitting device, which includes a step of laminating a cathode on a substrate, a step of laminating an organic light emitting layer, and a step of laminating a hole injection protective layer. And ion-implanting the hole-injecting protective layer, and laminating an upper transparent anode. The step of laminating the upper transparent anode may be performed by a sputtering method.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the organic EL device of the present invention will be described in detail. FIG. 2 shows an organic EL device according to the first embodiment of the present invention. The organic EL light emitting device shown in FIG. 2 includes a cathode 3, an organic EL layer 2, and an upper transparent anode 1. The organic EL layer 2 includes an electron injection layer 15, an electron transport layer 14, an organic EL layer 13, and a positive electrode. It comprises a hole transport layer 12 and a hole injection layer 11. Among these layers, the electron injection layer 15, the electron transport layer 14, and the hole transport layer 12 are layers that may be optionally provided.
[0024]
The cathode 3 is preferably made of a reflective metal or alloy. This is because the light emitted from the organic EL layer 2 can be reflected by a reflective metal or alloy and sent to the anode, which is the light extraction side. Preferred reflective metals and alloys include Al, Ag, Mo, W, and alloys thereof.
[0025]
The organic EL layer 2 is formed on the cathode 3 formed as described above. In the organic EL light emitting device of this embodiment, the organic EL layer 2 includes at least the organic light emitting layer 13 and the hole injection layer 11, and if necessary, the hole transport layer 12, the electron transport layer 14, and / or the electron transport layer 14. It has a structure with an injection layer 15 interposed. Specifically, for example, a layer having the following layer configuration is employed.
(1) Hole injection layer / organic light emitting layer
(2) hole injection layer / organic light emitting layer / electron injection layer
(3) hole injection layer / hole transport layer / organic light emitting layer / electron injection layer
(4) hole injection layer / organic light emitting layer / electron transport layer / electron injection layer
(5) hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer
(Here, the upper transparent anode 1 is connected to the organic light emitting layer or the hole injection layer, and the cathode 3 is connected to the organic light emitting layer or the electron injection layer).
[0026]
Known materials are used as the materials of the respective layers. In order to obtain blue to blue-green light emission, for example, a fluorescent whitening agent such as a benzothiazole-based, benzimidazole-based, benzoxazole-based, a metal chelated oxonium compound, a styrylbenzene-based compound is used in the organic light emitting layer 13. And aromatic dimethylidin compounds are preferably used.
[0027]
The electron transport layer 14 may be made of a quinoline derivative (for example, an organometallic complex having 8-quinolinol as a ligand), an oxadiazole derivative, a perylene derivative, a pyridine derivative, a pyrimidine derivative, a quinoxaline derivative, a diphenylquinone derivative, or a nitroquinone derivative. Substituted fluorene derivatives and the like can be used. Further, the electron injection layer 15 may be made of a material having a small work function, such as an alkali metal such as lithium or sodium, or an alkaline earth metal such as potassium, calcium, magnesium, or strontium, in order to improve the electron injection property. An electron-injecting metal or an alloy or compound (such as a fluoride) with another metal is used.
[0028]
The hole injection layer 11 that can be used in the present invention is formed of a material having an ionization potential corresponding to the work function of the cathode material and having high hole mobility. Materials that can be used include compounds having a triarylamine structure, for example, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD), 4,4′- Bis [N- (4-methylphenyl) -N-phenylamino] biphenyl (TPD), 4,4′-bis [N- (1-naphthyl) -N- (9-phenanthryl) amino] biphenyl (PPD), It includes trimers (TPTR), tetramers (TPTE), and pentamers (TPPE) in which triphenylamine is linearly linked at the phenyl group para-position. Since these materials have a high hole mobility, there is an advantage that the increase in the device resistance (that is, the decrease in the light emission starting voltage) is small even when the film thickness is increased. IDE-406 (made by Idemitsu Kosan) can be mentioned as a particularly preferred material. This material is an oligoamine with a high glass transition temperature and high hole mobility. Therefore, it is possible to form the hole injection layer 11 with a thickness that can reduce the damage that may be caused by the formation of the upper transparent anode 1 described later by sputtering. The hole injection layer 11 has a thickness of 30 to 1000 nm, preferably 30 to 300 nm, more preferably 60 to 100 nm.
[0029]
The functions of the hole injection layer 11 and the hole transport layer 12, the functions of the electron injection layer 15 and the electron transport layer 14, or the functions of the electron injection layer 15, the electron transport layer 14, and the organic light emitting layer 13 may be realized by separate layers. Or it may be implemented in a single layer.
[0030]
Since the upper transparent anode 1 emits light to the outside through the upper transparent anode 1, the upper transparent anode 1 is required to be transparent in the wavelength region of visible light, and is required to have a large work function in order to enhance hole injection properties. Regarding transparency, the upper transparent anode 1 preferably has a transmittance of 50% or more, more preferably 85% or more, for light having a wavelength of 400 to 800 nm. As a material for forming the upper transparent anode 1, ITO and IZO, which are transparent conductive oxides, are preferable. In order to improve the luminous efficiency, it is desirable that the upper transparent anode 1 has a thickness that gives a sufficiently low resistivity. The upper transparent anode 1 has a thickness of 30 nm or more, more preferably in the range of 100 to 300 nm.
[0031]
FIG. 3 shows an organic EL light emitting device according to a second embodiment of the present invention. In FIG. 3, a hole injecting protective layer 16 is provided between the organic EL layer 2 (hole injecting layer 11) and the upper transparent anode 1. The components other than the hole injecting protective layer 16 are the same as those of the device of the first embodiment.
[0032]
However, in the device of the present embodiment, the hole injection layer 11 is not an essential component, but it is preferable that the hole injection layer 11 be present in order to ensure hole injection properties. If a smooth hole movement is possible between the hole injection protective layer 16 and the hole transport layer 12 or between the hole injection protective layer 16 and the organic light emitting layer 13, the hole injection is performed. Layer 11 can be omitted. Further, when the hole injection layer 11 is laminated in the present embodiment, the thickness thereof can be made smaller than that in the first embodiment, and is preferably in the range of 60 to 100 nm.
[0033]
The hole-injecting protective layer 16 has a high ionization potential for smoothly injecting holes from the anode, and is formed of a material capable of preventing the surface from being deteriorated due to the collision of sputtered particles. The hole injecting protective layer 16 can be formed of a material containing phthalocyanine such as copper phthalocyanine (CuPc). The hole injecting protective layer 16 can be formed by vapor deposition, like the other layers of the organic EL layer 2, and has a thickness of 3 nm or more, preferably 3 to 10 nm.
[0034]
By using the hole injecting protective layer 16, an organic EL light emitting element having excellent characteristics such as luminous efficiency and luminous starting voltage can be formed while minimizing an increase in thickness.
[0035]
The organic EL light emitting device according to the third embodiment of the present invention is characterized in that, in the device according to the first embodiment, ions are implanted into a surface of the hole injection layer 11 which is in contact with the upper transparent anode 1. In order to increase the efficiency of hole injection, it is desirable that the ionization potential of the hole injection layer 11 and the work function of the upper transparent anode 1 completely match. However, it is difficult to select a material that completely matches the two. Therefore, the ionization potential of the surface of the hole injection layer or the work function of the anode surface is adjusted by some method so that the two agree. It is desired that In consideration of the stacking order, in the present invention, it is desirable to adjust the ionization potential on the surface of the hole injection layer by ion implantation.
[0036]
The hole injection layer 11 in the present embodiment is preferably within a range of 30 to 100 nm. By having such a thickness, it is possible to prevent ion implantation into a layer formed below without lowering light emission efficiency and increasing light emission start voltage. As the ions implanted into the hole injection layer, for example, Ar, Au, or the like can be used. The amount of ion implantation depends on the ionization potential of the hole injection layer used, the work function of the upper transparent anode, and the type of ions to be implanted. Confirmation of the ion implantation state and quantification of the ion implantation amount can be measured by a surface analysis method known in the art such as a fluorescent X-ray analysis method. By performing such ion implantation, the luminous efficiency can be improved and the luminescence starting voltage can be reduced.
[0037]
The organic EL light-emitting device according to the fourth embodiment of the present invention is characterized in that, in the device according to the third embodiment, ions are implanted into the surface of the hole-injecting protective layer 16 which is in contact with the upper transparent anode 1. And Also in this case, the ionization potential on the surface of the hole-injecting protective layer 16 and the surface work function of the upper transparent anode 1 can be matched by ion implantation. As a result, the luminous efficiency can be improved and the luminescence starting voltage can be reduced. The ion species and the implantation amount used for the ion implantation are the same as the ion implantation for the hole injection layer 11.
[0038]
It should be understood that a layer may be provided for improving the characteristics of the organic EL light emitting devices according to the first to fourth embodiments. Examples of such a layer include a passivation layer for covering the entire element and blocking oxygen or moisture in the surrounding environment to improve the life of the element, and between the substrate on which the organic EL light emitting element is manufactured and the cathode. A planarization layer or the like which is provided and planarizes the unevenness of the substrate surface can be given.
[0039]
The method for manufacturing an organic EL light-emitting element according to the fifth embodiment of the present invention is a method for manufacturing an organic EL light-emitting element according to the first embodiment. , A step of laminating the hole injection layer 11 having a thickness of 30 to 1000 nm, and a step of laminating the upper transparent anode 1.
[0040]
The substrate used in the method should be able to withstand the conditions (solvent, temperature, etc.) used to form the layers to be laminated, and preferably have excellent dimensional stability. The substrate can be transparent or opaque. Preferred materials include metals, ceramics, glass, and resins such as polyethylene terephthalate, polymethyl methacrylate, and the like. Borosilicate glass or soda lime glass is particularly preferred. In order to further enhance the luminous efficiency by increasing the reflectivity, a metal having high reflectivity such as Al, Ag, Mo, W, or a ceramic, glass, or resin (polyethylene terephthalate, polymethyl methacrylate) coated on the surface with the above metal Etc.) can be used. However, when the surface of the substrate on which the cathode 3 is laminated has conductivity, it is necessary to provide an insulating layer between the cathode 3 and the surface of the substrate.
[0041]
The step of laminating the cathode 3 on the substrate can be performed by a method such as vapor deposition, sputtering, or ion plating of the above-described cathode forming material. When the cathodes 3 are laminated, a single cathode may be formed by uniformly laminating the entire surface of the substrate, or a plurality of cathodes (line shape, square shape, etc.) divided into a large number by using a mask or a resist. (Which may have any shape).
[0042]
Next, the organic EL layer 2 is formed by laminating at least the organic light emitting layer 13 and the hole injection layer 11 on the cathode 3. If necessary, the electron injection layer 15, the electron transport layer 14, and / or the hole transport layer 12 may be laminated. Each of the above-mentioned layers is formed by evaporating the constituent material.
[0043]
Finally, the upper transparent anode 1 is laminated on the hole injection layer 11. This step is performed by laminating a transparent conductive oxide (ITO or IZO) by a sputtering method. As in the case of the cathode, a single upper transparent anode 1 may be formed by uniformly laminating the entire surface of the substrate, or may be divided into a plurality of upper transparent anodes (line shape) using a mask or a resist. , Or any shape such as a square). As described above, by providing the hole injection layer 11 having a thickness of 30 to 1000 nm, preferably 30 to 300 nm, more preferably 60 to 100 nm, damage at the time of sputtering is reduced, and the emission efficiency is reduced and the light emission is reduced. An increase in the starting voltage can be prevented.
[0044]
The sixth embodiment of the present invention is a method for manufacturing an organic EL light emitting device according to the second embodiment, in which a step of laminating a cathode 3 on a substrate, a step of laminating an organic EL layer 2, And a step of laminating the transparent protective layer 16 and a step of laminating the upper transparent anode 1.
[0045]
The step of laminating the cathode 3 and the step of laminating the upper transparent anode 1 can be performed in the same manner as in the above-described fifth embodiment.
[0046]
The organic EL layer 2 in the present embodiment includes at least the organic light emitting layer 13, and preferably has at least the organic light emitting layer 13 and the hole injection layer 11, and if necessary, the electron injection layer 15, the electron transport layer 14, And / or have a hole transport layer 12. The lamination of these layers is performed in the same manner as in the fifth embodiment. The lamination of the hole injecting protective layer 16 can be carried out by vapor deposition of the constituent materials as described above.
[0047]
The seventh embodiment of the present invention is a method of manufacturing an organic EL device according to the third embodiment, in which a step of laminating a cathode 3 on a substrate, a step of laminating an organic light emitting layer 13, and a step of injecting holes are performed. The method includes at least a step of laminating the layer 11, a step of ion-implanting the hole injection layer 11, and a step of laminating the upper transparent anode 1.
[0048]
Of the above-described steps, the steps other than the ion implantation step can be performed in the same manner as in the fifth embodiment. The ion implantation step is performed by applying an acceleration voltage to ions generated from the ion source and irradiating the accelerated ions to the surface of the hole injection layer. The acceleration voltage is set in a range such that ions are smoothly injected into the hole injection layer 11 but do not penetrate the layer. Although it depends on the material of the hole injection layer 11 to be used, it is generally appropriate to use an acceleration voltage in the range of 1 to 100 V.
[0049]
The eighth embodiment of the present invention relates to a method of manufacturing an organic EL light emitting device according to the fourth embodiment, wherein a step of laminating a cathode 3 on a substrate, a step of laminating an organic EL layer 2, The method includes a step of laminating the protective layer 16, a step of implanting ions into the hole-injecting protective layer 16, and a step of laminating the upper transparent anode 1.
[0050]
Of the above-described steps, the steps other than the ion implantation step can be performed in the same manner as in the sixth embodiment. The ion implantation step is performed by applying an acceleration voltage to ions generated from the ion source and irradiating the accelerated ions to the surface of the hole-injecting protective layer 16. The acceleration voltage is set in a range such that ions are smoothly injected into the hole-injecting protective layer 16 but do not penetrate the layer. Although it depends on the material of the hole injecting protective layer 16 to be used, it is generally appropriate to use an acceleration voltage in the range of 1 to 100 V.
[0051]
In the organic EL light emitting device of the present invention, the cathode 3 can be divided into a plurality of portions to form a plurality of independent light emitting portions, and used as a display. Further, a color conversion color filter may be provided to the display to provide a multicolor display. An example of such a multicolor display is shown in FIG. In the display of FIG. 4, a plurality of switching elements 22 such as TFTs or MIMs are provided on a substrate 21. The plurality of divided cathodes 3 are formed, and each of the plurality of divided cathodes 3 is electrically connected to each of the plurality of switching elements 22 on a one-to-one basis. The formation of the plurality of divided cathodes 3 can be performed by a method well known in the art, for example, using a mask or a photolithographic method using a photoresist.
[0052]
On the cathode 3, the organic EL layer 2 as described above is formed. The organic EL layer 2 may have the structure described in any of the first to fourth embodiments, and can be formed by the methods of the fifth to eighth embodiments, respectively. Further, an upper transparent anode 1 is formed on the organic EL layer 2. The upper transparent electrode 1 is a single electrode over the entire surface.
[0053]
On the other hand, a color conversion color filter 24 is provided on the transparent substrate 23 at a position corresponding to the plurality of divided cathodes 3. The color conversion color filter in this specification refers to a color conversion layer that converts the wavelength distribution of light from the organic EL layer 2 and a light in a specific wavelength range among the light from the organic EL layer 2 or the color conversion layer. This is a general term for a color filter layer that is transmitted. For example, when the organic EL layer 2 emits blue-green light, the red conversion color filter 24R includes a red conversion layer that performs blue-green light wavelength distribution conversion and outputs red light, and adjusts color purity as necessary. It may have a red color filter layer for improvement. The green conversion color filter 24G includes a green conversion layer that performs blue-green light wavelength distribution conversion and outputs green light, and may have a green color filter layer for improving color purity as needed. However, when the blue-green light of the organic EL layer 2 contains a sufficient amount of green component, the green conversion color filter 24G may be constituted only by the green color filter layer. In addition, the blue conversion color filter 24B may include a blue conversion layer that performs blue-green light wavelength distribution conversion and outputs blue light, but is usually composed of only a blue color filter layer. By providing the black mask 25 between the color conversion color filters 24 of each color, it is possible to improve the contrast ratio of the display. When the organic EL layer 2 emits white light, the red, green, and blue color conversion color filters are formed of color filter layers that do not perform wavelength distribution conversion.
[0054]
Finally, the substrate 21 provided with the organic EL light emitting element and the transparent substrate 23 provided with the color conversion color filter 24 are bonded while being aligned using, for example, an adhesive layer 26 provided at a peripheral portion. A multi-color display can be formed. This bonding step may be performed using any method known in the art. Further, the transparent substrate 23 provided with the above-mentioned color conversion color filter 24 is not limited to the organic EL light emitting element of the present invention, but may be a color filter panel for an organic EL light emitting element having another structure or another type of light source. It can also be used as
[0055]
FIG. 4 shows an example of an active matrix drive display using switching elements. However, it is also possible to form a passive matrix drive display using the organic EL light emitting element of the present invention. In that case, in addition to the cathode 3, the upper transparent electrode 1 is also divided into a plurality of portions. In practice, the cathode 3 and the upper transparent electrode 1 are divided into a plurality of portions in a line pattern, and the line pattern of the cathode 3 and the upper transparent electrode 1 are arranged so as to be orthogonal to the line pattern. Further, those skilled in the art will appreciate that optional layers may be provided to enhance the properties of the display in addition to the layers described above.
[0056]
【Example】
(Example 1)
A cathode 3 was formed on a glass substrate by depositing CrB with a thickness of 100 nm using a facing-type sputtering apparatus. Ar was used as a sputtering gas, and a sputtering power of 300 W was applied. Next, in order to improve the electron injection property, an electron injection layer 15 of MgAg (Mg: Ag = 9: 1) having a thickness of 10 nm was deposited.
[0057]
Thereafter, the substrate was moved to an organic layer deposition chamber without breaking vacuum. And pressure 1 × 10 ^-5 At Pa or less, aluminum tris (8-quinolinolate) (Alq) having a thickness of 60 nm was deposited as an organic light emitting layer 13 on the electron injection layer 15 at a film formation rate of 0.5 nm / s. Next, an organic EL layer 2 was obtained by depositing α-NPD having a thickness of 100 nm as the hole injection layer 11 at a film formation rate of 0.5 nm / s.
[0058]
Next, the substrate on which the organic EL layer 2 was formed was transferred to a facing-type sputtering apparatus, and IZO having a thickness of 100 nm was deposited by sputtering to form an upper transparent anode 1, thereby obtaining an organic EL light emitting device.
[0059]
(Example 2)
In the same manner as in Example 1, layers below the organic light emitting layer 13 were formed. Next, α-NPD having a thickness of 40 nm was deposited as the hole injection layer 11 at a deposition rate of 0.5 nm / s, and CuPc having a thickness of 40 nm was laminated as the hole injection protective layer 16. Finally, an upper transparent anode 1 was formed in the same manner as in Example 1 to obtain an organic EL light emitting device.
[0060]
(Example 3)
In the same manner as in Example 1, layers below the hole injection layer 11 were formed. Next, Ar ions were implanted into the surface of the hole injection layer 11 using an acceleration voltage of 5V. The injection of Ar ions into the surface of the hole injection layer 11 was confirmed by the fluorescent X-ray analyzer. Finally, an upper transparent anode 1 was formed in the same manner as in Example 1 to obtain an organic EL light emitting device.
[0061]
(Example 4)
In the same manner as in Example 2, layers below the hole injecting protective layer 16 were formed. Next, Au ions were implanted into the surface of the hole injecting protective layer 16 using an acceleration voltage of 5 V. The injection of Au ions into the surface of the hole injecting protective layer 16 was confirmed by the X-ray fluorescence analyzer. Finally, an upper transparent anode 1 was formed in the same manner as in Example 1 to obtain an organic EL light emitting device.
[0062]
(Comparative Example 1)
The method of Example 1 was repeated except that the thickness of the hole injection layer was set to 40 nm, to obtain an organic EL light emitting device.
[0063]
(Evaluation)
The light emitting elements of each of the examples and comparative example 1 were 100 cd / m ² And the current was measured at that time to determine the luminous efficiency. Further, a light emission starting voltage at which each light emitting element starts light emission was measured. The results are shown in Table 1 below.
[0064]
[Table 1]

[0065]
As is clear from Table 1, the organic EL light emitting devices of Examples 1 to 4 according to the present invention exhibited higher luminous efficiency and lower luminescence starting voltage than the device of Comparative Example 1. This is because the damage of the hole injection layer 11 of the device and / or the ionization potential of the hole injection layer 11 and the work function of the upper transparent electrode 1 which occurred in Comparative Example 1 during sputtering for forming the upper transparent electrode 1 were observed. Probably due to inconsistency.
[0066]
Further, the devices of Examples 3 and 4 exhibited higher luminous efficiency and lower luminescence starting voltage than the devices of Examples 1 and 2, respectively. This is presumably because the ionization potential of the hole injection layer and the work function of the upper transparent anode were well matched by ion implantation on the surface of the hole injection layer 11.
[0067]
【The invention's effect】
As described above, according to the present invention, the upper electrode is used as an anode, 1) the thickness of the hole injection layer is in the range of 30 to 1000 nm, and 2) the holes are provided between the organic EL layer and the upper electrode. Providing an injectable protective layer and / or 3) ion-implanting the hole-injectable layer or the hole-injectable protective layer to the outside through an upper electrode exhibiting excellent luminous efficiency and luminescence onset voltage. A so-called top emission type organic EL light emitting device that emits light was obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a conventional organic EL light emitting device.
FIG. 2 is a schematic sectional view showing the organic EL light emitting device according to the first embodiment of the present invention.
FIG. 3 is a schematic sectional view showing an organic EL light emitting device according to a second embodiment of the present invention.
FIG. 4 is a schematic sectional view showing an example of a multicolor display formed by the organic EL device of the present invention.
[Explanation of symbols]
1 Top transparent anode
2,102 Organic EL layer
3 Cathode
11,111 hole injection layer
12,112 hole transport layer
13,113 Organic light emitting layer
14, 114 electron transport layer
15, 115 electron injection layer
16 Hole injection protective layer
21 Substrate
22 Switching element
23 Transparent substrate
24 (R, G, B) color conversion color filter layer
25 Black Mask
26 Adhesive layer
101 anode
103 cathode

Claims (8)

On a substrate, a cathode, an organic EL layer, and an upper transparent anode are provided. The organic EL layer includes at least an organic light emitting layer and a hole injection layer, and the hole injection layer is in contact with the upper transparent anode. An organic EL light emitting device, wherein the hole injection layer has a thickness of 30 to 1000 nm, and emits light to the outside through the upper transparent anode. An organic EL light emitting device having a cathode, an organic EL layer, a hole injecting protective layer, and an upper transparent anode on a substrate, and emitting light to the outside through the upper transparent anode. On a substrate, a cathode, an organic EL layer, and an upper transparent anode are provided. The organic EL layer includes at least an organic light emitting layer and a hole injection layer, and the hole injection layer is in contact with the upper transparent anode. An organic EL light emitting device, wherein ions are implanted into a surface of the hole injection layer which is in contact with the upper transparent anode, and light is emitted to the outside through the upper transparent anode. On the substrate, there is provided a cathode, an organic EL layer, a hole-injecting protective layer, and an upper transparent anode, wherein the hole-injecting protective layer is in contact with the upper transparent anode to form the hole-injecting protective layer. An organic EL light-emitting device, wherein ions are implanted into a surface of a layer in contact with the upper transparent anode, and emit light to the outside through the upper transparent anode. A step of laminating a cathode on a substrate, a step of laminating an organic light emitting layer, a step of laminating a hole injection layer having a thickness of 30 to 1000 nm, and a step of laminating an upper transparent anode. A method for producing an organic EL light-emitting element. An organic EL light emitting device comprising: a step of laminating a cathode on a substrate; a step of laminating an organic light emitting layer; a step of laminating a hole injecting protective layer; and a step of laminating an upper transparent anode. Manufacturing method. Laminating a cathode on a substrate, laminating an organic light emitting layer, laminating a hole injection layer, performing ion implantation on the hole injection layer, and laminating an upper transparent anode. A method for manufacturing an organic EL light-emitting device, comprising at least: Laminating a cathode on a substrate, laminating an organic light-emitting layer, laminating a hole-injecting protective layer, performing ion implantation on the hole-injecting protective layer, and forming an upper transparent anode. And a step of stacking.

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