JP2005044799A - Organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent device capable of efficiently extracting light from a cathode on an upper face side and displaying a high-quality image by preventing an organic layer and an electron injection layer from being oxidized and relaxing damage on the organic layer and the injection layer caused by spattering in manufacturing. <P>SOLUTION: The element comprises at least a base material; an anode sequentially disposed onto the base material; an organic electroluminescent layer; a light transmissive inductive protecting layer; and a light transmissive cathode. The protecting layer is made of metal or metal and oxide thereof. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescent device, and more particularly to an organic electroluminescent device capable of extracting light from a cathode on the upper surface side.

  Organic electroluminescent elements (hereinafter also referred to as organic electroluminescent elements or organic EL elements) have high visibility due to self-coloring, are all solid-state displays unlike liquid crystal displays, have excellent impact resistance, and have a response speed of It has advantages such as being fast, not being easily affected by temperature changes, and having a large viewing angle, and in recent years, its use as a light emitting element in an image display device has attracted attention.

  The structure of the organic EL element is based on a laminated structure of an anode / light emitting layer / cathode, and a structure in which a transparent anode is formed on a base material using a glass substrate or the like is usually employed. In this case, light emission is taken out from the substrate side (anode side).

  On the other hand, in recent years, attempts have been made to extract light from the cathode side (upside light emission) in the organic EL element with the cathode transparent. By realizing the top emission, first, when the anode is made transparent together with the cathode, a transparent light emitting element as a whole becomes possible. An arbitrary color can be adopted as the background color of such a transparent light emitting element, and it becomes possible to make a colorful display other than during light emission, and the decorativeness is improved. In addition, when the color filter layer or the color conversion layer is used due to the realization of the top emission, the above layers can be arranged on the light emitting layer. Further, since light emission is not blocked by the TFT (Thin Film Transistor) of the active drive display device, a display device with a high aperture ratio can be realized.

  As an example of the organic EL element that can emit light from the upper surface by making the cathode transparent, an organic layer including an organic EL light emitting layer is interposed between the anode and the cathode. There is disclosed a configuration comprising a crystalline transparent conductive layer, in which this electron injection metal layer is in contact with an organic layer (see Patent Document 1).

  Further, in order to prevent the cathode material from diffusing into the organic layer that is the organic EL light emitting layer, a Ca diffusion barrier layer is provided between the cathode and the organic layer to prevent short-circuiting of the organic EL element and deterioration of characteristics. The structure which was made is disclosed (refer patent document 2).

  Further, as an example of double-sided light emission, a configuration is disclosed in which a conductive layer such as Ag, Mg, or TiN is interposed between the transparent cathode and the light emitting layer in order to reduce the resistance of the transparent cathode (Patent Document). 3).

  Furthermore, a configuration using TiN for the anode is disclosed for the purpose of preventing intrusion and diffusion of oxygen and indium into the organic layer (see Patent Document 4 and Patent Document 5).

However, in the conventional organic EL device that enables top emission, the electron injection layer cannot be oxidized due to the introduction of oxygen in the process of forming the transparent cathode or the release of oxygen from the target. There was a problem that the characteristics of the electron injection layer deteriorated and a high-quality image display could not be obtained. In general, a transparent electrode such as ITO (indium-tin oxide) is formed by a sputtering method. When a transparent cathode is formed by sputtering, an organic layer including an organic EL light emitting layer or an electron injection layer is sputtered. There is a problem in that the light emission characteristics are deteriorated by receiving impacts of the generated particles and Ar ⁺ during sputtering.

Japanese Patent Laid-Open No. 10-162959 Japanese Patent Laid-Open No. 10-144957 JP-A-10-125469 JP 2002-15859 A JP 2002-15860 A

  The present invention has been made in view of such a situation, and in an organic electroluminescent device, the organic layer and the electron injection layer are prevented from being oxidized, and the organic layer and the electron injection layer generated by sputtering at the time of forming the transparent cathode. An object of the present invention is to provide an organic electroluminescent device capable of taking out light from a cathode on the upper surface side with high efficiency by reducing the damage of the upper surface and capable of displaying a high quality image.

  In order to achieve such an object, the present invention provides a base material, an anode sequentially provided on the base material, an organic electroluminescent layer, a light-transmitting conductive protective layer, and a light-transmitting cathode. And the conductive protective layer is made of a metal or an oxide of the metal and the metal.

  According to the present invention, the conductive protective layer is formed of a light-transmitting metal thin film formed by a vacuum film-forming method in which oxygen is not introduced in the film-forming step, or a light-transmitting metal and an oxide of the metal. In order to form a thin film, the organic layer and the electron injection layer are prevented from being oxidized by oxygen not only during the formation of the conductive protective layer but also during the formation of the light-transmitting cathode. The organic electroluminescence device can be reduced in impact due to the generated particles, has little leakage current, and has excellent light emission characteristics and durability. Further, by providing a conductive protective layer, an organic electroluminescence element capable of taking out light from a cathode on the upper surface side with high reliability without causing characteristic deterioration and capable of displaying a high-quality image can be obtained.

  In the above invention, the metal used for the conductive protective layer is preferably in the range of 0 ≦ kd <0.11λ, where k is the extinction coefficient of the metal, d is the film thickness, and λ is the wavelength. .

  In the present invention, the metal oxide contained in the conductive protective layer preferably has a band gap of 2.9 eV or more.

  Furthermore, in the present invention, the conductive protective layer includes at least one metal selected from the group consisting of zinc, tin, lead, indium, gallium, magnesium, and aluminum, or at least one metal and at least one metal oxide. It is preferable that it consists of a combination with a thing.

  In the present invention, the cathode is preferably made of a conductive oxide, has a thickness in the range of 10 nm to 500 nm, and preferably has a light transmittance of 50% or more in the visible region of 380 nm to 780 nm.

  Furthermore, in the present invention, the sheet resistance of the cathode including the conductive protective layer is preferably 20Ω / □ or less.

  In the present invention, the anode may be one or a combination of two or more metal groups having a work function of 4.5 eV or more, or two or more of the metal groups having a work function of 4.5 eV or more. It is preferable that the alloy is made of any of the above metals, or one or a combination of two or more of the conductive inorganic oxide groups.

  In this case, the anode has a structure in which a layer made of the metal or alloy and a layer made of the conductive inorganic oxide are laminated in order from the base material side, and may have light reflectivity. Alternatively, it may be made of the above metal or alloy and have light reflectivity.

  In the present invention as described above, the conductive protective layer interposed between the electron injecting layer and the organic electroluminescent layer and the cathode is used for organic electroluminescence by oxygen by introducing oxygen at the time of forming the cathode or releasing oxygen from the target. It serves to prevent oxidation of the electron injection layer of the device.

  According to the present invention, a conductive protective layer is interposed between the cathode and the organic layer including the electron injection layer and the organic electroluminescent layer, and oxygen is not introduced into the conductive protective layer in the film forming process. Since it is a thin film made of at least one kind of metal or metal and its metal oxide formed by a vacuum film forming method, the organic layer and the electron injecting layer are light-transmitting as well as the conductive protective layer. Oxidation by oxygen is prevented even during film formation of a negative electrode, which makes the organic EL element highly reliable with little deterioration in characteristics, and high quality by extracting light from the cathode on the upper surface side with high efficiency. Thus, an organic electroluminescent element capable of displaying an image is obtained.

Hereinafter, the organic EL device of the present invention will be described in detail.
The organic EL device of the present invention includes at least a base material, an anode sequentially provided on the base material, an organic electroluminescent layer, a light-transmitting conductive protective layer, and a light-transmitting cathode. The conductive protective layer is made of a metal or a metal and an oxide of the metal.

First, the organic EL element of the present invention will be described with reference to the drawings. FIG. 1 is a basic configuration conceptual diagram showing an embodiment of an organic EL element of the present invention. In FIG. 1, an organic EL element includes a base material 1, a first electrode (anode) 2 sequentially provided on the base material 1, an organic layer 3 including an organic electroluminescent layer, an electron injection layer 4, a light transmitting property. And a second electrode (cathode) 6 having optical transparency.
Hereinafter, each structure of such an organic EL element is demonstrated.

1. Base material First, the base material 1 used for this invention is demonstrated. The material that can be used as the substrate 1 is not particularly limited as long as it is a material having self-supporting properties. Moreover, when providing the base material 1 under the anode 2 of a metal layer, it does not need to have transparency in particular.

  As the substrate 1, for example, quartz or glass, a silicon wafer, glass on which TFT (thin film transistor) is formed, and as a polymer substrate, polycarbonate (PC), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), Examples include polyphenylene sulfide (PPS), polyimide (PI), polyamideimide (PAI), polyethersulfone (PES), polyetherimide (PEI), polyetheretherketone (PEEK), and the like.

  Among these, quartz (glass), silicon wafer, or super engineering plastics such as polyimide (PI), polyamideimide (PAI), polyethersulfone (PES), polyetherimide (PEI), and polyetheretherketone (PEEK) are preferable. . This is because they have a heat resistance of 200 ° C. or higher, and the substrate temperature in the manufacturing stage can be increased in consideration of the process in the manufacturing process of the TFT of the active drive display device. However, when a polymer material is used, in order to prevent the organic layer 3 from being deteriorated by the gas generated from the base material 1, a gas barrier made of silicon oxide, silicon nitride, or the like is formed on at least the anode 2 formation surface of the base material 1. It is necessary to provide a layer.

  The thickness of the base material 1 can be set in consideration of the material, the usage status of the image display device, and the like, and can be set to about 0.005 to 5 mm, for example.

2. 1st electrode The 1st electrode (anode) 2 which comprises the organic EL element of this invention will not be specifically limited if it consists of an electroconductive material, For example, Au, Ta, W, Pt, Ni, Pd, Cr And a combination of metals such as Cu, Mo, or oxides thereof, alloys such as Al alloys, Ni alloys, Cr alloys, etc., or a laminated structure of these metal materials. Further, conductive inorganic oxides such as In-Sn-O, In-Zn-O, Zn-O, Zn-O-Al, Zn-Sn-O, conductive polymers such as metal-doped polythiophene, α -Si, (alpha) -SiC can be mentioned.

  Since the anode 2 has a role of supplying holes to the organic layer 3, it is preferable to use a conductive material having a large work function, and in particular, at least one metal having a work function of 4.5 eV or more, or these It is preferable that the anode 2 is formed of at least one material included in the group consisting of a metal alloy or a conductive inorganic oxide. Since the anode metal is easily oxidized when the work function is less than 4.5 eV, the work function is preferably 4.5 eV or more.

  The thickness of the anode 2 is preferably in the range of 40 to 500 nm although it depends on the material. When the thickness of the anode 2 is less than 40 nm, the resistance may increase. When the thickness exceeds 500 nm, the upper layer (the organic layer 3, the electron injection layer) is formed due to a step existing at the end of the patterned anode 2. This is because the conductive protective layer 5 and the cathode 6) may be cut or disconnected, or the anode 2 and the cathode 6 may be short-circuited.

Examples of the method for forming the anode 2 include a sputtering method, a vacuum heating vapor deposition method, an EB vapor deposition method, and an ion plating method. The specific resistance value is preferably 1 × 10 ⁻² Ω · cm or less, more preferably 5 × 10 ⁻⁴ Ω · cm or less. In order to prevent power loss due to electrode resistance, a lower resistance is preferable.

3. Organic Layer The organic layer 3 constituting the organic EL device of the present invention is usually composed of an organic electroluminescent layer, a hole injection transport layer, a hole transport layer, an electron transport layer, and the like. As such an organic layer 3 in the present invention, it is essential to include at least one organic electroluminescent layer. It is also possible to combine the organic electroluminescent layer and each of the above layers into the organic layer 3 composed of a plurality of layers.

  In addition, the method for forming the organic layer 3 on the anode 2 used in the present invention is not particularly limited as long as the method enables high-definition patterning because of the necessity of patterning. For example, a method for forming the organic layer 3 in a pattern by a vapor deposition method, a printing method, an ink jet method, or the like, or a method for applying a material for forming the organic layer 3 as a coating liquid, such as a spin coating method, a casting method, or a dipping method. Coating methods such as a coating method, a bar coating method, a blade coating method, a roll coating method, a gravure coating method, a flexographic printing method, a spray coating method, and a self-assembly method (alternate adsorption method, self-assembled monolayer method). . Among these, in particular, in the present invention, it is preferable to form the organic layer 3 by using a vapor deposition method, a spin coating method, and an ink jet method.

  When a conductive material made of a metal as described later is used as the conductive protective layer 5 as in the present invention, the work function is large (4.0 eV or more), and the energy at the interface between the conductive protective layer 5 and the organic electroluminescent layer is large. The barrier becomes high, and it is difficult to inject electrons directly from the conductive protective layer 5 to the organic electroluminescent layer under a low voltage. Therefore, a structure in which an electron injection layer or an electron injection transport layer is provided on the conductive protective layer 5 side is preferable. The electron injection layer or the electron injection transport layer needs to have sufficient light transmittance in order to extract light from the cathode 6 on the upper surface side with high efficiency. The hole injecting and transporting layer and the electron injecting and transporting layer may have a laminated structure in which an injection function layer and a transport layer are separately provided.

(1) Organic electroluminescent layer Hereinafter, the organic electroluminescent layer which comprises the organic layer 3 used for this invention is demonstrated.
The organic electroluminescent layer constituting the organic layer 3 has the following functions.
-Injection function: a function capable of injecting holes from the anode 2 or the hole injection layer when an electric field is applied, and a function capable of injecting electrons from the cathode 6 or the electron injection layer 4 -Transport function: injected charges (electrons and electrons Function to move holes) by the force of an electric field ・ Light emission function: A function to provide a field for recombination of electrons and holes and connect it to light emission

  As a material of the organic electroluminescent layer having such a function, a material generally known as a light emitting layer material for an organic EL element can be used, and there is no particular limitation. For example, Tris (8- High molecular weight materials such as metal complex dyes such as (quinolinolato) aluminum complex (Alq3) and polydialkylfluorene derivatives are preferably used.

  The thickness of the organic electroluminescent layer is not particularly limited, and can be, for example, about 10 to 200 nm.

  In the organic EL device of the present invention, the organic electroluminescent layer is an essential layer, and is a layer that requires patterning when manufacturing full-color and multi-color displays. As a material for forming such an organic electroluminescent layer, a dye-based, metal complex-based, or polymer-based luminescent material can be generally used. Hereinafter, a luminescent material will be described as a material for forming such an organic electroluminescent layer.

(I) Dye-type material As the dye-type material, cyclopentamine derivative, tetraphenylbutadiene derivative, triphenylamine derivative, oxadiazol derivative, pyrazoloquinoline derivative, distyrylbenzene derivative, distyrylarylene derivative, silole derivative, Examples thereof include thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, pyrazoline dimers, and the like.

(Ii) Metal complex materials Metal complex materials include aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazole zinc complex, benzothiazole zinc complex, azomethyl zinc complex, porphyrin zinc complex, europium complex, iridium metal complex, platinum metal. Complex, etc., center metal has Al, Zn, Be etc. or rare earth metal such as Tb, Eu, Dy etc., and ligand has oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure, etc. A metal complex etc. can be mentioned.

(Iii) Polymeric materials Polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, etc., polyfluorene derivatives, polyvinylcarbazole derivatives, the above dye bodies, metal complexes Examples include those obtained by polymerizing a system light emitting material.

(2) Hole injection transport layer, hole transport layer The hole injection transport layer is not particularly limited as long as it is a layer capable of transporting holes injected from the anode 2 into the organic electroluminescent layer. . For example, a hole injection layer having a function of stably injecting holes injected from the anode 2 into the organic electroluminescent layer, and a function of transporting holes injected from the anode 2 into the organic electroluminescent layer. When it consists of any one of the hole transport layers which it has, the case where it consists of those combinations, and the case where it consists of a layer which has these both functions may be sufficient.

  Furthermore, the thickness of the hole injecting and transporting layer is not particularly limited as long as its function is sufficiently exerted, but it is within the range of 10 nm to 300 nm, and particularly within the range of 30 nm to 100 nm. preferable.

  Such a hole injecting and transporting layer is not particularly limited as long as it is a material that stably transports holes injected from the anode 2 to the organic electroluminescent layer. Specifically, N- (1-naphthyl) -N-phenylbedidine (α-NPD), 4,4,4-tris (3-methylphenylphenylamino) triphenylamine (MTDATA), and higher molecular weight Examples of the material include poly3,4 ethylenedioxythiophene (PEDOT), polyvinylcarbazole (PVCz), polyaniline derivatives, polyphenylene vinylene derivatives, and the like. As the hole transport compound, an arbitrary one can be selected and used from known compounds conventionally used for the hole injection transport layer of the organic EL device.

(3) an electron injection layer The material of the electron injection layer 4, an alkali metal or alkaline earth metal oxides, fluorides _{(e.g., LiF, NaF, LiO 2,} MgF 2, CaF 2, BaF 2) or the like Is mentioned. Among these, an alkaline earth metal fluoride (MgF ₂ , CaF ₂ , BaF ₂ ) is particularly preferably used since the stability and life of the organic layer 3 can be improved. This is because the alkaline earth metal fluoride is less reactive with water than the alkali metal compound or alkaline earth metal oxide, and absorbs less water during or after film formation. It is. Further, the alkaline earth metal fluoride has a higher melting point and better heat resistance stability than the alkali metal compound.

  The thickness of the electron injection layer 4 is preferably in the range of about 0.2 to 10 nm because the oxides and fluorides of the above alkali metals and alkaline earth metals are insulative.

  Further, in addition to the electron injection layer 4, by providing a single metal material having a work function of 4.0 eV or less as the electron injection layer 4, electrons can be easily injected. Specifically, Ba, Ca, Li, Cs, Mg, etc. are mentioned. When the electron injection layer 4 made of such a metal material is formed, the film thickness is preferably in the range of 0.2 nm to 50 nm, particularly 0.2 nm to 20 nm. This is because the electron injection layer 4 is also required to have translucency because of the need to extract light from the transparent electrode on the upper surface.

  Further, as the electron injecting and transporting layer, a metal doped layer obtained by doping an electron transporting organic material with an alkali metal or an alkaline earth metal can be formed. Examples of the electron transporting organic material include bathocuproin (BCP) and bathophenanthroline (Bphen). Examples of the doped metal material include Li, Cs, Ba, and Sr. The molar ratio of the electron transporting organic material to the metal in the metal doped layer is about 1: 1 to 1: 3, preferably about 1: 1 to 1: 2. The thickness of the electron injecting and transporting layer composed of such a metal doped layer is about 5 to 500 nm, preferably about 10 to 100 nm, because the electron mobility is large and the light transmittance is higher than that of a single metal.

(4) Electron Transport Layer The material for forming the organic electron transport layer is not particularly limited as long as it can transport the electrons injected from the electron injection layer 4 into the light emitting layer. Specifically, examples of the electron transporting organic material include Alq3 (aluminum quinolinol complex), BCP (vasocupron), and Bpehn (vasophenanthroline).

(5) Conductive protective layer The conductive protective layer 5 protects the electron injection layer 4 and the organic layer 3 (sputtering, EB, ion plate) in the step of forming a transparent electrode for forming the cathode 6 and the function of charge transport. (Protection from film-forming processes such as coating). When a transparent electrode is formed on the electron injection layer 4 by sputtering, the electron injection layer 4 and the organic layer 3 receive a high energy amount of Ar ⁺ at several hundred volts, so that the structure of the organic electroluminescent layer changes. In the electron injection, non-radiative quenching is caused at the interface between the organic electroluminescent layer and the transparent electrode, and the light emission characteristics are deteriorated. Further, when the electron injection layer 4 is made of an alkali metal or an alkaline earth metal, the electron injection layer 4 is easily oxidized, and oxygen is introduced in an electrode forming process such as ITO or IZO in sputtering, or from the target. Oxygen release may oxidize the metal used for the electron injection layer 4 and lose the electron injection function. The conductive protective layer 5 is provided between the electron injection layer 4 and the second electrode 6 for the purpose of protecting the electron injection layer 4 and the organic layer 3, thereby reducing spatter damage of the electron injection layer 4 and the organic layer 3. As a result, the luminous efficiency and durability of the organic EL element can be improved.

  The conductive protective layer 5 is a thin film made of at least one kind of light-transmitting metal formed by a vacuum film forming method in which oxygen is not introduced in the film forming process, and is a multilayer film of two or more kinds of metals, or 2 A film in which more than one kind of metal is mixed may be used. The conductive protective layer 5 may be a thin film made of a light-transmitting metal and an oxide of the metal. When a thin film made of a metal oxide is included, the metal oxide thin film is more preferably provided on the cathode 6 side. In addition, the conductive protective layer 5 may be formed by alloying a plurality of metals constituting the metal oxide.

  As the metal, in order to make the light transmittance of the metal film in the visible region 50% or more, when the extinction coefficient of the metal is k, the film thickness is d, and the wavelength is λ, 0 ≦ kd <0.11λ The range of is preferable. The extinction coefficient k can be obtained by measuring the material deposited on the silicon wafer with an ellipsometer. Furthermore, the band gap of the metal oxide contained in the conductive protective layer 5 is preferably 2.9 eV or more. Such metals and metal oxides are not particularly limited as long as the above conditions are satisfied. For example, metals such as zinc, lead, tin, indium, gallium, magnesium, aluminum, gold, silver, and the like These metal oxides can be mentioned. In addition, after forming the conductive protective layer made of these simple metals, the band gap of the conductive protective layer 5 may be 2.9 eV or more by performing oxidation treatment of the protective layer.

  This is because when the band gap is less than 2.9 eV, the metal oxide is colored to reduce the transmittance in the visible region. Examples of the metal oxide include Sn-O, In-O, In-Sn-O, In-Zn-O, Zn-O, Ga-O, Zn-Sn-O, and Ga-In-O. Can be mentioned.

  The thickness of the conductive protective layer 5 having such characteristics is preferably selected as appropriate so as to satisfy the relational expression of 0 ≦ kd <0.11λ in accordance with the characteristics of the metal and metal oxide used. Generally, in the case of a thin film made of a metal, it is about 5 to 30 nm, preferably about 5 to 20 nm. In the case of a thin film made of a layer containing a metal oxide, it is about 5 to 300 nm, preferably about 10 to 100 nm. is there.

  Examples of the vacuum film forming method for forming the conductive protective layer 5 include a resistance heating vapor deposition method, an ion beam vapor deposition method, a sputtering method, and an ion plating method.

(6) Second electrode The second electrode (cathode) 6 is not particularly limited as long as it is made of a transparent conductive material. For example, In-Sn-O, In-Zn-O, Zn-O , Zn—O—Al, Zn—Sn—O, and other conductive oxides.

  The thickness of the cathode 6 is preferably in the range of 10 to 500 nm, and the light transmittance in the visible region of 380 to 780 nm is preferably 50% or more. If the thickness of the cathode 6 is less than 10 nm, the conductivity becomes insufficient, and if it exceeds 500 nm, the light transmittance becomes insufficient, and when the organic EL element is deformed in the manufacturing process or after manufacturing, the cathode 6 It is not preferable because defects such as cracks are likely to occur.

  Furthermore, the sheet resistance of the cathode 6 including the conductive protective layer 5 is preferably 20Ω / □ or less.

  Such a cathode 6 can be formed by a vacuum film forming method such as a sputtering method, an ion plating method, or an electron beam method. In the formation of such a cathode 6, oxidation of the electron injection layer 4 due to oxygen introduction or oxygen release from the target is blocked by the conductive protection layer 5, thereby preventing deterioration of charge injection characteristics to the organic layer 3. The

(7) Others In the present invention, a color filter layer and / or a color conversion phosphor layer may be provided on the cathode 6, and the color purity of the light of each color may be improved by increasing the color purity.

  As the color filter layer, for example, a resin prepared by dispersing one or a plurality of pigments such as azo, phthalocyanine, and anthraquinone in a photosensitive resin in each of a blue colored layer, a red colored layer, and a green colored layer It can be formed using a composition.

  The color conversion phosphor layer is formed by applying a coating solution in which a desired fluorescent dye and resin are dispersed or solubilized by spin coating, roll coating, cast coating, or the like. The red conversion phosphor layer, the green conversion phosphor layer, and the blue conversion phosphor layer can be formed by a patterning method using a photolithography method.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Next, an Example is shown and this invention is demonstrated further in detail.
[Example 1]
As a substrate, a transparent glass substrate (non-alkali glass NA35 manufactured by NH Techno Glass Co., Ltd.) having a thickness of 40 mm × 40 mm and a thickness of 0.7 mm was prepared. A thin film (thickness 100 nm) was formed. In the above Ag thin film formation, Ar was used as the sputtering gas, the pressure was 0.15 Pa, and the DC output was 200 W. Next, a thin film (thickness 30 nm) of indium tin oxide (ITO) was formed on the Ag thin film by a magnetron sputtering method in order to have a role of promoting hole injection. In the above ITO thin film formation, a mixed gas of Ar and O ₂ (volume ratio Ar: O ₂ = 100: 1) was used as the sputtering gas, and the pressure was 0.1 Pa and the DC output was 150 W.

  Next, a photosensitive resist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied onto the anode, mask exposure, development (using NMD3 manufactured by Tokyo Ohka Kogyo Co., Ltd.), etching is performed, and the anode is formed. A pattern was formed.

  Next, the transparent glass substrate provided with the anode is washed, subjected to UV ozone treatment, and then in the air, the polyethylene dioxythiophene represented by the following structural formula (1) is formed on the transparent glass substrate so as to cover the anode. -Polystyrene sulfonate (PEDOT-PSS) was apply | coated by the spin coat method, and it dried and formed the positive hole injection transport layer (thickness 80nm).

(However, n is 10,000 to 500,000.)

  Subsequently, poly (dioctyl divinylene fluorene represented by the following structural formula (2) is formed on the hole injecting and transporting layer in a low oxygen (oxygen concentration 1 ppm or less) and low humidity (water vapor concentration 1 ppm or less) state glove box. Co-anthracene) (PF) was applied by a spin coating method and dried to form a light emitting layer (thickness 80 nm).

(However, n is 100,000 to 1,000,000.)

Furthermore, Ca was vapor-deposited with a thickness of 5 nm on the light emitting layer to form an electron injection layer. The deposition conditions were a degree of vacuum of 5 × 10 ⁻⁵ Pa and a film formation rate of 1 kg / second.

Sn (refractive index n = 4.7, extinction coefficient k=1.6@1000 nm) was vapor-deposited with a thickness of 20 nm on the electron injection layer to form a conductive protective layer. The deposition conditions were a degree of vacuum of 5 × 10 ⁻⁵ Pa and a film formation rate of 1 kg / second.

Next, an ITO thin film (thickness 100 nm) was formed by magnetron sputtering to form a cathode. The ITO thin film is formed using a mixed gas of Ar and O ₂ (volume ratio Ar: O ₂ = 200: 1) as a sputtering gas, a pressure of 5.5 × 10 ⁻² Pa, a DC output of 150 W, and a composition. The film speed was 4 liters / second.

  Moreover, ITO was separately formed on the Sn thin film on the transparent glass substrate under the same conditions as described above, and the specific resistance and the light transmittance in the visible region of 380 to 780 nm were measured with respect to this. As a result, the surface resistance value of the ITO thin film including the Sn thin film was measured and found to be 18Ω / □. The visible region average transmittance was about 60%.

(Measurement of surface resistance)
The surface resistance value (Ω / □) was measured by a four-probe method using Loresta-GP manufactured by Mitsubishi Chemical Corporation.

(Specific resistance measurement)
The specific resistance value (Ω · cm) was calculated by multiplying the measured surface resistance value (Ω / □) by the film thickness (cm). The film thickness was measured using Nanopics 1000 manufactured by Seiko Instruments Inc.

(Measurement of light transmittance)
It measured in room temperature and air | atmosphere using the ultraviolet visible spectrophotometer (Shimadzu Corporation UV-2200A).

  Thereafter, sealing was performed with alkali-free glass in a glove box in a low oxygen (oxygen concentration 1 ppm or less) and low humidity (water vapor concentration 1 ppm or less) state.

As described above, an anode patterned in a line shape having a width of 2 mm, and an electron injection layer, a conductive protective layer, and a cathode formed in a line shape having a width of 2 mm so as to be orthogonal to the anode have four light emitting areas (areas). An organic EL device having 4 mm ² ) was produced.

The current density when a voltage of 6 V was applied to the anode and cathode of this organic EL element was 200 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 12000 cd / m ² .

  From the results of the current density and luminance characteristics, it is confirmed that the presence of the conductive protective layer made of Sn thin film prevents the oxidation of the light emitting layer and the electron injection layer due to the introduction of oxygen at the time of cathode formation and the damage during sputtering. It was done.

[Example 2]
Example 1 except that a thin film (thickness 20 nm) of In (refractive index n = 1.018, extinction coefficient k=2.08@500 nm) was formed under the same conditions as the conductive protective layer instead of the Sn thin film. In the same manner as above, an organic EL device was produced.

  As a result of measuring the surface resistance value of the ITO thin film including the In thin film in the same manner as in Example 1, it was 18Ω / □. Moreover, as in Example 1, the light transmittance in the visible region 380 to 780 nm was measured, and as a result, the visible region average transmittance was about 70%.

The current density when a voltage of 6 V was applied to the anode and cathode of the organic EL element was 190 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 12000 cd / m ² . As a result of the current density and luminance characteristics, the presence of a conductive protective layer made of an In thin film in the light emitting area prevents oxidation and sputtering of the light emitting layer and electron injection layer due to oxygen introduction during cathode formation. It was confirmed that

[Example 3]
Instead of the Sn thin film, a thin film (thickness 20 nm) of Zn (refractive index n = 0.773, extinction coefficient k=3.912@545 nm) was used as the conductive protective layer by vacuum evaporation (vacuum degree 5 × 10 ⁻⁵ Pa). The organic EL device was manufactured in the same manner as in Example 1 except that the film was formed at a film formation rate of 1.0 cm / sec.

  In addition, it was 19 ohms / square as a result of measuring the surface resistance value of the ITO thin film containing Zn thin film like Example 1. FIG. In the same manner as in Example 1, the visible region average transmittance of ITO containing the Zn thin film was about 70%.

The current density when a voltage of 6 V was applied to the anode and cathode of the organic EL display device was 190 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 12000 cd / m ² . From the results of the current density and luminance characteristics, it is confirmed that the presence of the conductive protective layer made of Zn thin film prevents oxidation and sputtering of the light-emitting layer and electron injection layer caused by oxygen introduction during the cathode formation. It was done.

[Example 4]
Except that a thin film (thickness 20 nm) of Pb (refractive index n = 1.68, extinction coefficient k=3.67@700 nm) was formed as the conductive protective layer instead of the Sn thin film, the same procedure as in Example 1 was performed. An organic EL element was produced.

  In addition, it was 15 ohms / square as a result of measuring the surface resistance value of the ITO thin film containing a Pb thin film similarly to Example 1. FIG. In the same manner as in Example 1, the visible region average transmittance in the visible region of 380 to 780 nm of ITO containing the Pb thin film was about 60%.

The current density when a voltage of 6 V was applied to the anode and cathode of the organic EL element was 200 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 11000 cd / m ² . From the results of the current density and luminance characteristics, it was confirmed that the presence of a conductive protective layer made of a Pb thin film prevented oxidation of the light-emitting layer and electron injection layer due to oxygen introduction during cathode formation and damage during sputtering. It was done.

[Example 5]
As in Example 1, except that Sn (thickness 20 nm) was formed as the conductive protective layer, and the second electrode (cathode) was formed of an indium zinc oxide (IZO) thin film, which was also an inorganic oxide, instead of ITO. Thus, an organic EL element was produced. Only Ar was used as the sputtering gas, and the pressure was 5.5 × 10 ⁻² Pa, the DC output was 150 W, and the deposition rate was 4 Å / sec.

  In addition, it was 19 ohms / square as a result of measuring the surface resistance value of the ITO thin film containing Sn thin film similarly to Example 1. FIG. In the same manner as in Example 1, the visible region average transmittance of the IZO thin film including the Sn thin film was about 70%.

The current density when a voltage of 6 V was applied to the anode and cathode of the organic EL element was 210 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 12000 cd / m ² . From the results of the current density and the luminance characteristics, it was confirmed that the presence of the conductive protective layer made of the Sn thin film prevented the electron injection layer from being oxidized and damaged by sputtering during the cathode formation.

[Comparative Example 1]
An organic EL element was produced in the same manner as in Example 1 except that the conductive protective layer was not formed.
The current density when a voltage of 6 V was applied to the anode and cathode of the organic EL element was 30 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 2000 cd / m ² . From the results of the current density and the luminance characteristics, it was confirmed that in the element in which the conductive protective layer was not formed, the light emission characteristics deteriorated due to the oxidation of the electron injection layer by oxygen at the time of forming the cathode.

[Example 6]
First, in the same manner as in Example 1, an anode is formed on a transparent glass substrate, and then the transparent glass substrate provided with the anode is exposed to oxygen plasma, and then the anode is covered by a vacuum heating vapor deposition method. A hole transport layer (thickness: 50 nm) made of bis (N-naphthyl) -N-phenylbenzidine (α-NPD) represented by the following structural formula (3) was formed on the transparent glass substrate. The film formation conditions for this hole transport layer were a degree of vacuum of 5 × 10 ⁻⁵ Pa, a film formation rate of 3 L / second, and a heating temperature of 350 ° C.

Next, a tris (8-quinolinolato) aluminum complex (Alq3) represented by the following structural formula (4) was formed on the hole transport layer by vacuum deposition to form a light emitting layer (thickness 60 nm). The conditions for forming the light emitting layer were a degree of vacuum of 5 × 10 ⁻⁵ Pa and a film formation rate of 3 L / second.

Further, a vapor deposition layer of bathocuproin (BCP) and Li represented by the following structural formula (5) was formed on the light emitting layer by vacuum deposition to form an electron injection layer (thickness 20 nm). The deposition conditions were a degree of vacuum of 5 × 10 ⁻⁵ Pa and a film formation rate of 3 L / second with each material.

  Subsequently, the conductive protective layer Sn and the cathode ITO were formed in the same manner as in Example 1, and finally sealed with sealing glass.

The current density when a voltage of 6 V was applied to the anode and cathode of this organic EL element was 40 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 3000 cd / m ² . From the results of the current density and the luminance characteristics, it was confirmed that the presence of the conductive protective layer made of the Sn thin film prevented the electron injection layer from being oxidized and damaged by sputtering during the cathode formation.

[Comparative Example 2]
An organic EL element was produced in the same manner as in Example 6 except that the conductive protective layer was not formed.
The current density when a voltage of 6 V was applied to the anode and cathode of this organic EL element was 2.8 mA / cm ² , and the luminance of the light emitting area measured from the upper surface (cathode) side was 160 cd / m ² . From the results of the current density and the luminance characteristics, it was confirmed that the element in which the conductive protective layer was not formed did not prevent the electron injection layer from being oxidized or damaged by sputtering during the cathode formation.

It is a basic composition conceptual diagram showing one embodiment of the organic electroluminescence (EL) element of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Organic electroluminescent element 2 ... Base material 3 ... Anode 4 ... Organic layer 5 ... Conductive protective layer 6 ... Cathode

Claims (9)

  A substrate, and an anode, an organic electroluminescent layer, a light-transmitting conductive protective layer, and a light-transmitting cathode sequentially provided on the substrate, the conductive protective layer being a metal or a metal And an organic electroluminescent element comprising the metal oxide.   2. The metal used for the conductive protective layer is in a range of 0 ≦ kd <0.11λ, where k is an extinction coefficient of the metal, d is a film thickness, and λ is a wavelength. The organic electroluminescent element of description.   The organic electroluminescence device according to claim 1 or 2, wherein the metal oxide contained in the conductive protective layer has a band gap of 2.9 eV or more.   The conductive protective layer is made of at least one metal selected from the group consisting of zinc, tin, lead, indium, gallium, magnesium, and aluminum, or a combination of at least one metal and at least one metal oxide. The organic electroluminescent element according to any one of claims 1 to 3, wherein the organic electroluminescent element is.   The cathode is made of a conductive oxide, has a thickness in a range of 10 nm to 500 nm, and has a light transmittance of 50% or more in a visible region of 380 nm to 780 nm. The organic electroluminescent element according to claim 1.   The organic electroluminescent element according to any one of claims 1 to 5, wherein a sheet resistance of the cathode including the conductive protective layer is 20 Ω / □ or less.   The anode is one or a combination of two or more metals in a metal group having a work function of 4.5 eV or more, an alloy composed of two or more metals in the metal group, or a conductive inorganic oxide. The organic electroluminescent element according to any one of claims 1 to 6, wherein the organic electroluminescent element is one of a group or a combination of two or more.   The anode has a structure in which a layer made of the metal or the alloy and a layer made of the conductive inorganic oxide are laminated in order from the base material side, and has light reflectivity. The organic electroluminescent element of description. The organic electroluminescent device according to claim 7, wherein the anode is made of the metal or the alloy and has light reflectivity.

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