JP6061450B2 - ORGANIC ELECTROLUMINESCENT ELEMENT AND METHOD FOR PRODUCING ORGANIC ELECTROLUMINESCENT ELEMENT - Google Patents

Description

  The present invention relates to an organic electroluminescence element applicable to uses such as a display device and a lighting device, and a manufacturing method thereof.

  In recent years, organic electroluminescence elements using organic substances (hereinafter referred to as organic EL elements) are promising in applications such as solid-state light-emitting inexpensive large-area full-color display elements and light-emitting elements of writing light source arrays. Therefore, research and development of organic EL elements are being actively promoted.

  The organic EL element is generally a thin-film element that includes a substrate, a first electrode, a light emitting layer, and a second electrode, and the first electrode, the light emitting layer, and the second electrode are formed on the substrate in this order. One of the first electrode and the second electrode constitutes an anode, and the other constitutes a cathode. The light emitting layer is composed of one or a plurality of organic compound layers containing an organic light emitting substance.

  In the organic EL element having such a configuration, when a voltage is applied between the first electrode and the second electrode, holes are injected from the anode into the light emitting layer, and electrons are injected from the cathode into the light emitting layer. Then, when holes and electrons injected into the light emitting layer recombine in the light emitting layer, the energy level of the organic light emitting material returns from the conduction band to the valence band, and the energy generated at this time is converted from the light emitting layer as light. Released. In the organic EL element, light emission can be obtained by such a principle.

  In order to put an organic EL element that emits light according to the above-described principle into a surface light emitting element, it is necessary to efficiently extract light confined inside the element and improve the front luminance on the light emitting surface. Therefore, conventionally, various techniques have been proposed to solve this problem (see, for example, Patent Documents 1 to 3).

  Patent Documents 1 and 2 propose techniques for providing a diffusion structure on the light exit surface of an organic EL element (surface light emitting element). In Patent Document 3, a sheet (diffusion sheet or the like) having prism-like or lens-like irregularities formed on the surface is provided on the light emission surface of an organic EL element (surface light source element). Techniques for forming irregularities have been proposed.

  Moreover, since the organic light emitting material (organic substance) used for the organic EL element has low resistance to moisture and oxygen, the light emitting performance of the organic EL element is likely to deteriorate due to the influence of moisture and oxygen in the atmosphere. Further, the characteristics of the electrode are rapidly deteriorated by oxidation in the atmosphere. Therefore, conventionally, in order to suppress the deterioration of each part in the organic EL element as described above, a sealing for preventing the ingress of moisture and oxygen at the uppermost part of the organic EL element (organic EL element body). A member (sealing layer) is provided (see, for example, Patent Documents 4 and 5).

In Patent Documents 4 and 5, a glass substrate is used as a sealing member, and the sealing member is fixed to an organic EL element main body via an adhesive or the like (hereinafter referred to as a close-contact type sealing method). Has been proposed. Specifically, for example, an inorganic compound film such as a GeO film or a SiO ₂ film as a protective film on the second electrode side upper layer of the organic EL element body including the substrate, the first electrode, the light emitting layer, and the second electrode. Form. Next, for example, a glass substrate (sealing member) is fixed on the protective film via an adhesive, an adhesive layer formed of a material such as a photocurable resin, or the like.

  Conventionally, in a top emission type organic EL element, for example, a sealing member such as a non-water-permeable glass base material, a barrier film formed by laminating an inorganic layer and an organic layer, and suppressing water vapor transmission Is provided in the uppermost layer on the light emission side.

JP 2000-323272 A JP 2000-231985 JP 2000-148032 A JP-A-4-212284 JP-A-5-182759

  As described above, various techniques have been proposed for improving the light emission characteristics of organic EL elements. In this technical field, organic EL elements having a simpler configuration and excellent light emission characteristics have been proposed. Development is required. The present invention has been made to meet the above-mentioned demands, and an object of the present invention is to provide an organic EL element having a simpler structure and excellent light emission characteristics, and a method for producing the same. That is.

In order to solve the above problems, an organic EL element of the present invention includes an element substrate, a first electrode formed on the element substrate, an organic compound layer formed on the first electrode and including a light emitting layer, an organic A second electrode formed on the compound layer; and a sealing substrate formed on the second electrode. Furthermore, the organic EL element of the present invention is formed between at least one of the element substrate and the first electrode and between the sealing substrate and the second electrode, and diffuses light emitted from the light emitting layer. A functional resin layer. Furthermore, in the organic EL element of the present invention, the light diffusing resin layer has a refractive index different from the refractive index of the base material layer formed of a thermoplastic resin and the base material layer, and the inside of the base material layer. And a plurality of diffusion portions dispersed in the substrate. The diffusion portion is made of a microcrystalline region of a thermoplastic resin.

Moreover, the manufacturing method of the organic EL element of this invention is performed in the following procedure. First, a first electrode is formed on an element substrate. Next, an organic compound layer including a light emitting layer is formed on the first electrode. Next, a second electrode is formed on the organic compound layer. Next, a sealing substrate is formed on the second electrode. Then, a light diffusing resin layer for diffusing light emitted from the light emitting layer is formed between the element substrate and the first electrode and between at least one of the sealing substrate and the second electrode. Among these, forming the light diffusing resin layer includes forming a base material layer of the light diffusing resin layer with a thermoplastic resin on the sealing substrate, and forming the first electrode on the element substrate, The element body and the sealing base are arranged so that the second electrode of the element body formed by laminating the organic compound layer and the second electrode in this order faces the base material layer on the sealing substrate. Bonding the materials and heating the bonded element body and sealing substrate to produce a microcrystalline region within the thermoplastic resin of the base material layer.

  As described above, in the present invention, the light diffusing resin layer that diffuses the light emitted from the light emitting layer is provided between the element substrate and the first electrode and at least one of the sealing substrate and the second electrode. To form. Thereby, in this invention, it can obtain the organic EL element which has a simpler structure, and has the outstanding light emission characteristic, and its manufacturing method.

It is a schematic structure sectional view of an organic EL device concerning one embodiment of the present invention. It is a figure for demonstrating the manufacturing method of the organic EL element which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the organic EL element which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the organic EL element which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the organic EL element which concerns on one Embodiment of this invention. It is a schematic structure sectional view of an organic EL element produced in various examples.

  Hereinafter, an organic EL element according to an embodiment of the present invention and an example of a manufacturing method thereof will be specifically described with reference to the drawings. However, the present invention is not limited to the following example.

<1. Configuration of organic EL element>
[Overall configuration of organic EL element]
In FIG. 1, the structural example of the organic EL element which concerns on one Embodiment of this invention is shown. FIG. 1 is a schematic cross-sectional view of the organic EL element of this embodiment.

  The organic EL element 10 includes an organic EL element body 11 (element body), a light diffusing resin layer 12, and a sealing substrate 13. The organic EL element 10 shown in FIG. 1 is an organic EL element manufactured by a close-contact type sealing method, and the sealing substrate 13 is provided with the organic EL element body 11 through the light diffusing resin layer 12. It is fixed to. In the present embodiment, a configuration example of the organic EL element 10 that extracts at least light emitted from the organic EL element body 11 from the sealing substrate 13 side will be described.

  The organic EL element body 11 includes an element substrate 1, an anode 2 (first electrode), an organic compound layer including a hole transport layer 3, a light emitting layer 4, and an electron transport layer 5, and a cathode 6 (second electrode). And a gas barrier layer 7. In this embodiment, the anode 2, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5, the cathode 6, and the gas barrier layer 7 are laminated on the element substrate 1 in this order. At this time, the gas barrier layer 7 is laminated so as to cover the anode 2, the hole transport layer 3, the light emitting layer 4, the electron transport layer 5, and the cathode 6 as shown in FIG. 1.

  The light diffusing resin layer 12 is provided on the gas barrier layer 7 so as to cover the gas barrier layer 7. The light diffusing resin layer 12 diffuses the light emitted from the light emitting layer 4 and emits the diffused light to the sealing substrate 13. The light diffusing resin layer 12 also has a role of an adhesive layer that adheres to the organic EL element body 11 and the sealing substrate 13.

  In addition, in the organic EL element 10 of this embodiment, since the light inject | emitted from the light emitting layer 4 is taken out at least from the cathode 6 side as mentioned above, between the cathode 6 and the sealing base material 13, it is light diffusibility. Although the example which provides the resin layer 12 is shown, this invention is not limited to this. When taking out the light emitted from the light emitting layer 4 from the anode 2 side, a light diffusing resin layer 12 may be provided between the anode 2 and the element substrate 1. Further, when the light emitted from the light emitting layer 4 is taken out from both the anode 2 side and the cathode 6 side, between the anode 2 and the element substrate 1 and between the cathode 6 and the sealing substrate 13. The light diffusing resin layer 12 may be provided.

Moreover, the laminated structure of the element substrate 1, each electrode, the organic compound layer, and the sealing base material 13 in the organic EL element 10 of this embodiment is not limited to the example shown in FIG. You may make it laminated structure (1)-(4).
(1) Element substrate / anode / light emitting layer / electron transport layer / cathode / sealing substrate (2) Element substrate / anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode / sealing Substrate (3) element substrate / anode / hole transport layer (hole injection layer) / light emitting layer / hole blocking layer / electron transport layer / electron injection layer (cathode buffer layer) / cathode / sealing substrate (4 ) Element substrate / anode / hole injection layer (anode buffer layer) / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer (cathode buffer layer) / cathode / sealing substrate

  In the examples of the laminated structures (1) to (4), the light diffusing resin layer 12 is omitted. However, when light is extracted from the cathode side as in this embodiment, the light diffusing resin layer 12 is used. Is provided between the cathode and the sealing substrate. In addition, as is clear from the examples of the laminated structures (1) to (4), the organic EL element 10 according to the present embodiment may be configured such that the gas barrier layer 7 is not provided.

  In addition, the configuration of this embodiment in which the light diffusing resin layer 12 is provided between the anode 2 and the element substrate 1 and / or between the cathode 6 and the sealing substrate 13 is an adhesion type sealing. The present invention is also applicable to an organic EL element manufactured using a sealing method other than the method (for example, a method such as can sealing).

  Hereinafter, the structure of each part and each layer of the organic EL element 10 shown in FIG. 1 will be described more specifically.

[Element substrate]
The element substrate 1 (base, substrate, base material, support) can be formed of a transparent material such as glass or plastic. In particular, the element substrate 1 is preferably composed of a glass substrate, a quartz substrate, or a transparent resin film.

  As a material for forming the transparent resin film, for example, polyester such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) can be used. Moreover, as a formation material of a transparent resin film, materials, such as polyethylene, a polypropylene, a cellophane, can be used, for example. Furthermore, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate (TAC), cellulose esters such as cellulose nitrate, or their derivatives are formed into a transparent resin film. It can be used as a material.

  Examples of the material for forming the transparent resin film include polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide, and polyether sulfone (PES). , Polyphenylene sulfide, polysulfones, polyether imide, polyether ketone imide, polyamide, fluororesin, nylon, polymethyl methacrylate, acrylic, polyarylate, and the like can be used. Furthermore, for example, a cycloolefin resin called Arton (registered trademark: manufactured by JSR) or Apel (registered trademark: manufactured by Mitsui Chemicals) can be used as a material for forming a transparent resin film.

When the element substrate 1 is composed of a transparent resin film, a film made of an inorganic material or a film made of an organic material is formed on the surface of the transparent resin film in order to suppress, for example, water vapor or oxygen from passing into the organic EL element 10. Alternatively, a hybrid film obtained by stacking these films may be provided. In this case, the barrier property such that the water vapor permeability (environmental condition: 25 ± 0.5 ° C., relative humidity (90 ± 2)% RH) is about 0.01 g / [m ² · day · atm] or less. It is preferable to form the said film with a film. In addition, the film has an oxygen permeability of about 10 ⁻³ cm ³ / [m ² · day · atm] or less and a water vapor permeability of about 10 ⁻³ g / [m ² · day · atm] or less. It is more preferable to use a barrier film such that Further, the film has an oxygen permeability of about 10 ⁻³ cm ³ / [m ² · day · atm] or less and a water vapor permeability of about 10 ⁻⁵ g / [m ² · day · atm] or less. It is particularly preferable to use a barrier film such that The “water vapor permeability” as used herein is a value measured by an infrared sensor method in accordance with JIS (Japanese Industrial Standard) -K7129 (1992), and “oxygen permeability” is JIS- It is a value measured by a coulometric method based on K7126 (1987).

  As a material for forming the above-described barrier film (the coating film), any material can be used as long as it can suppress deterioration of the organic EL element 10, for example, entry of factors such as moisture and oxygen into the organic EL element 10. Can be used. For example, the barrier film can be composed of a coating made of an inorganic material such as silicon oxide, silicon dioxide, or silicon nitride. In order to improve the brittleness of the barrier film, the barrier film is preferably composed of a hybrid film in which a film made of the inorganic material and a film made of an organic material are laminated. In this case, the order of laminating the film made of an inorganic material and the film made of an organic material is arbitrary, but it is preferable to laminate a plurality of both alternately.

  In addition, as a method for forming the barrier film as described above, any method can be used as long as it can form the barrier film on the element substrate 1 (transparent resin film). For example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma polymerization method (see JP 2004-68143 A), Techniques such as plasma CVD (Chemical Vapor Deposition), laser CVD, thermal CVD, and coating can be used. In the present embodiment, it is particularly preferable to use an atmospheric pressure plasma polymerization method.

[anode]
The anode 2 (first electrode) is an electrode film that supplies (injects) holes to the light-emitting layer 4 and has a high work function (4 eV or more), such as metals, alloys, electrically conductive compounds, and these It is made of an electrode material such as a mixture.

Specifically, in the organic EL element 10, when light is extracted from the anode 2 side, the anode 2 is, for example, a metal such as Au or a metal such as CuI, ITO (Indium Tin Oxide), SnO ₂ , or ZnO. It can be formed of a light transmissive electrode material such as a compound. In this case, the anode 2 can also be formed of an amorphous transparent electrode material such as IDIXO (registered trademark: In ₂ O ₃ —ZnO).

  In the organic EL element 10, when light is extracted from the anode 2 side, the light transmittance of the anode 2 is preferably greater than about 10%. The sheet resistance (surface resistance) of the anode 2 is several hundred Ω / sq. The following is preferable. Further, the film thickness of the anode 2 varies depending on the forming material, but is usually set in a range of about 10 to 1000 nm, preferably about 10 to 200 nm.

  On the other hand, in the organic EL element 10, when light is not extracted from the anode 2 side (when light is extracted only from the cathode 6 side), the anode 2 has a high reflectivity such as a metal, an amorphous alloy, a microcrystalline alloy, or the like. It can also be formed of an electrode material having

  The anode 2 having the above-described configuration can be formed on the element substrate 1 by a technique such as vapor deposition or sputtering. At this time, the anode 2 may be formed in a desired shape pattern by using a photolithography technique. In the case where the accuracy of the shape pattern is not required in the anode 2 (when the accuracy is about 100 μm or more), a desired shape pattern is formed when the anode 2 is formed by a technique such as vapor deposition or sputtering. Alternatively, the anode 2 having a desired pattern may be formed on the element substrate 1 through the mask.

[Hole transport layer, hole injection layer]
(1) Hole Transport Layer The hole transport layer 3 is a layer that transports (injects) holes supplied from the anode 2 to the light emitting layer 4. Further, the hole transport layer 3 also acts as a barrier that prevents inflow of electrons from the cathode 6 side. Therefore, the term hole transport layer 3 may be used in a broad sense and includes a hole injection layer and / or an electron blocking layer.

  The hole transport layer 3 can be formed, for example, by laminating a forming material (hole transport material), which will be described later, on the anode 2 using a technique such as a spin coating method or a vapor deposition method. Although the film thickness of the positive hole transport layer 3 is suitably set according to conditions, such as a positive hole transport material to be used, for example, it is about 5 nm-about 5 micrometers normally, Preferably it sets in the range of about 5-200 nm. The hole transport layer 3 may be provided as a single layer or a plurality of layers. When the hole transport layer 3 has a single layer structure, one or more of the hole transport materials described later may be included in the hole transport layer 3.

  As the hole transport material, any material of an organic material and an inorganic material can be used as long as the material can exhibit the above-described action of transporting (injecting) holes and blocking the inflow of electrons. it can. Specifically, as a hole transport material, for example, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives , Styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers (particularly thiophene oligomers), and the like can be used.

  Moreover, as a hole transport material, compounds, such as a porphyrin compound and an aromatic tertiary amine compound (styrylamine compound), can be used, for example. In particular, in this embodiment, it is preferable to use an aromatic tertiary amine compound (for example, a compound having the structural formula (2) HT-1 used in various examples described later) as a hole transport material.

  Aromatic tertiary amine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -[1,1'-biphenyl] -4,4'-diamine (TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1-bis (4-di-p- Tolylaminophenyl) cyclohexane, N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl, 1,1-bis (4-di-p-tolylaminophenyl) -4-phenyl Cyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N'-di (4-methoxyphenyl) ) -4, '-Diaminobiphenyl, N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis (diphenylamino) quadriphenyl, N, N, N-tri (p- Compounds such as (tolyl) amine can be used. As aromatic tertiary amine compounds, 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene, 4-N, N-diphenylamino- (2- A styrylamine compound such as diphenylvinyl) benzene and 3-methoxy-4'-N, N-diphenylaminostilbenzene can be used. Furthermore, as aromatic tertiary amine compounds, those having two condensed aromatic rings in the molecule as described in US Pat. No. 5,061,569, for example, 4,4′- Three bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD) and three triphenylamine units as described in JP-A-4-308688 were linked in a starburst type. A compound such as 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) may be used.

  In addition, as the hole transport material, for example, a polymer material in which the various hole transport materials described above are introduced into a polymer chain, or a polymer material in which the various hole transport materials described above are used as a polymer main chain. It can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as a hole transport material and a material for forming a hole injection layer described later.

  Furthermore, as a hole transport material, for example, JP-A-11-251067, J. Org. Huang et. al. A material referred to as a so-called p-type hole transport material as described in literatures (Applied Physics Letters 80 (2002), p. 139) may be used. Note that when such a material is used as a hole transport material, a more efficient light-emitting element can be obtained.

  In the present embodiment, the hole transport layer 3 may be doped with impurities to form the hole transport layer 3 having a high p property (hole rich). Examples thereof include, for example, JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J.A. Appl. Phys. , 95, 5773 (2004). When such a hole-rich hole transport layer 3 is used, the organic EL element 10 with lower power consumption can be produced.

(2) Hole Injection Layer In the organic EL element 10 of the present embodiment, although not shown in FIG. 1, between the anode 2 and the light emitting layer 4 or between the anode 2 and the hole transport layer 3, A hole injection layer (anode buffer layer) may be provided. The hole injection layer is a layer provided between the anode 2 and the organic layer compound layer in order to lower the driving voltage of the organic EL element 10 and improve the light emission luminance.

  Here, a detailed description of the structure of the hole injection layer is omitted. For example, “Organic EL element and its forefront of industrialization” (issued on November 30, 1998 by NTT) The structure of the hole injection layer is described in detail in Chapter 2, “Electrode Material” (pages 123-166). As a material for forming the hole injection layer (anode buffer layer), compounds described in JP-A No. 2000-160328 can be used. Further, as will be described in various examples described later, for example, a compound containing PEDOT (poly (3,4-ethylenedioxythiophene): structural formula (1) described later) or the like is used as a hole injection layer (anode buffer layer). ).

[Light emitting layer]
The light emitting layer 4 is injected directly from the anode 2 or from the anode 2 through the hole transport layer 3 and directly from the cathode 6 or from the cathode 6 through the electron transport layer 5. This layer emits light by recombination with electrons. The portion that emits light may be inside the light emitting layer 4 or may be an interface between the light emitting layer 4 and a layer adjacent thereto. Moreover, the light emitting layer 4 may be provided only in one layer, and may be provided in multiple layers.

  In the present embodiment, the light emitting layer 4 is formed of an organic light emitting material including a light emitting host and a light emitting dopant. In the light emitting layer 4 having such a configuration, an arbitrary emission color can be obtained by appropriately adjusting the emission wavelength of the light emitting dopant, the kind of the light emitting dopant to be contained, and the like.

  Moreover, the light emitting layer 4 can be produced by, for example, laminating an organic light emitting material on the hole transport layer 3 by using a method such as spin coating or vapor deposition. The film thickness of the light emitting layer 4 can be arbitrarily set. For example, the homogeneity of the constituent films, the prevention of unnecessary application of a high voltage during light emission, and the emission color with respect to the drive current From the standpoint of improving stability, the thickness of the light emitting layer 4 is preferably adjusted to a range of, for example, about 2 to 200 nm, and more preferably adjusted to a range of about 5 nm to 100 nm.

  Here, the structure of the light emission host and the light emission dopant contained in the light emitting layer 4 is demonstrated to a specific example.

(1) Light emitting host As the light emitting host (host compound) contained in the light emitting layer 4, it is preferable to use a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than about 0.1. In particular, it is preferable to use a compound having a phosphorescence quantum yield of less than about 0.01 as a light-emitting host. The volume ratio of the light emitting host in the light emitting layer 4 is preferably about 50% or more among various compounds contained in the light emitting layer 4.

  A known host compound can be used as the light-emitting host included in the light-emitting layer 4. At that time, one type of host compound may be used, or a plurality of types of host compounds may be used in combination. By using a plurality of types of host compounds, the mobility (movement amount) of electric charges (holes and / or electrons) can be adjusted, and the light emission efficiency of the organic EL element 10 can be improved.

  Examples of the host compound having the above-described characteristics include known low-molecular compounds, high-molecular compounds having repeating units, and low-molecular compounds having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light-emitting host). ) And the like can be used. As the host compound, it is preferable to use a compound having a hole transporting function, an electron transporting function, a function of preventing emission of longer wavelengths, and a high Tg (glass transition temperature). However, the “glass transition temperature (Tg)” here is a value obtained by a method based on JIS-K7121, using a DSC (Differential Scanning Colorimetry) method.

  Specifically, as host compounds, for example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002 No. 334786, No. 2002-8860, No. 2002-334787, No. 2002-15871, No. 2002-334788, No. 2002-43056, No. 2002-334789, No. 2002-75645. Gazette, 2002-338579 gazette, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette. No. 2002-231453, No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-260861, No. 2002-280183. , 2002-299060, 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like can be used.

  In this embodiment, the host compound is preferably a carbazole derivative, and particularly preferably a carbazole derivative and a dibenzofuran compound (for example, structural formulas (3) used in various examples described later. ) Host compound with H-A).

(2) Light emission dopant As a light emission dopant, a fluorescent dopant, a phosphorescence dopant, etc. can be used, for example. However, from the viewpoint of improving the light emission efficiency, it is preferable to use a phosphorescent dopant as the light emitting dopant.

  A phosphorescent dopant is a compound that can emit light from an excited triplet. Specifically, the phosphorescent dopant is a compound that emits phosphorescence at room temperature (25 ° C.) and has a phosphorescence quantum yield of about 0.01 or more at 25 ° C. However, in this embodiment, it is preferable to use a phosphorescent dopant having a phosphorescence quantum yield of about 0.1 or more. The phosphorescence quantum yield can be measured, for example, by the method described on page 398 of "4th edition Experimental Chemistry Course 7 Spectroscopy II" (1992 edition, Maruzen). In addition, the phosphorescence quantum yield in the solution can be measured using various solvents, but in this embodiment, the phosphorescence dopant can be used to emit phosphorescence quantum yield of about 0.01 or more in any solvent. Any dopant may be used.

  Moreover, the light emitting layer 4 may contain one kind of light emitting dopant, or may contain a plurality of kinds of light emitting dopants having different light emission maximum wavelengths. By using a plurality of types of light emitting dopants, it is possible to mix a plurality of lights having different emission wavelengths, thereby obtaining light of an arbitrary emission color. For example, white light can be obtained by making the light emitting layer 4 contain a blue dopant, a green dopant, and a red dopant (three kinds of light emitting dopants).

  As the process (principle) of light emission (phosphorescence emission) in the light emitting layer 4 containing the light emitting host and the phosphorescent dopant described above, there are the following two kinds of processes.

  The first light emission process is an energy transfer type light emission process. In this type of light emission process, first, carriers recombine on the light emitting host in the light emitting layer 4 where carriers (holes and electrons) are transported, thereby generating an excited state of the light emitting host. The energy generated at this time moves from the light emitting host to the phosphorescent dopant (the energy level of the excited state moves from the excited level of the light emitting host to the excited level (excited triplet) of the light emitting dopant), and this As a result, light emission occurs from the phosphorescent dopant.

  The second light emission process is a carrier trap type light emission process. In this type of light emission process, the phosphorescent dopant traps carriers (holes and electrons) in the light emitting layer 4. As a result, carrier recombination occurs on the phosphorescent dopant and light is emitted from the phosphorescent dopant. In any of the light emission processes described above, the energy level in the excited state of the phosphorescent dopant needs to be lower than the energy level in the excited state of the light emitting host.

  As a phosphorescent dopant that causes the above-described light emission process, a desired phosphorescent dopant is appropriately selected from various known phosphorescent dopants (phosphorescent compounds) used in conventional organic EL devices. Can do. For example, as the phosphorescent dopant, a complex compound containing a metal element of Group 8 to Group 10 in the periodic table of elements can be used. Among such complex compounds, it is preferable to use any one of an iridium compound, an osmium compound, a platinum compound (platinum complex compound), and a rare earth complex as a phosphorescent dopant. In this embodiment, it is particularly preferable to use an iridium compound (for example, a light-emitting dopant having the structural formulas (4) to (6) used in various examples described later) as the phosphorescent dopant.

In this specification, light emitted from the organic EL element 10 is measured with a spectral radiance meter (CS-1000, manufactured by Konica Minolta Sensing Co., Ltd.), and the measurement result is expressed as CIE (International Commission on Illumination) chromaticity coordinates. (For example, refer to FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Society of Color Science, The University of Tokyo Press, 1985)), the color of the light emitted from the organic EL element 10 Color. Specifically, the term “white” as used herein means that the chromaticity in the CIE 1931 color system at 1000 cd / m ² is X = 0.33 ± 0 when the 2-degree viewing angle front luminance is measured by the above method. .07, Y = 0.33 ± 0.07.

  In this embodiment, as a method for obtaining white light emission, as described above, a method in which a light emitting host contains a plurality of light emitting dopants having different emission wavelengths is used, but the present invention is not limited to this. For example, a blue light emitting layer, a green light emitting layer, and a red light emitting layer may be laminated to form the light emitting layer 4, and white light emission may be obtained by mixing light emitted from each color light emitting layer.

[Electron transport layer, electron injection layer]
(1) Electron Transport Layer The electron transport layer 5 is a layer that transports (injects) electrons supplied from the cathode 6 to the light emitting layer 4. Further, the electron transport layer 5 also acts as a barrier that prevents the inflow of holes from the anode 2 side. Therefore, the term electron transport layer 5 may be used in a broad sense and includes an electron injection layer and / or a hole blocking layer.

  The electron transport layer 5 can be produced, for example, by laminating a forming material (electron transport material), which will be described later, on the light emitting layer 4 using a technique such as spin coating or vapor deposition. The film thickness of the electron transport layer 5 is appropriately set according to, for example, conditions such as the electron transport material used, but is usually set in the range of about 5 nm to 5 μm, preferably about 5 to 200 nm. The electron transport layer 5 may be provided as a single layer or a plurality of layers. When the electron transport layer 5 has a single layer structure, one or more materials among the electron transport materials described later may be included in the electron transport layer 5.

  An electron transporting layer 5 adjacent to the cathode 6 side of the light emitting layer 4 (when the electron transporting layer 5 has a single layer structure, the electron transporting layer 5 is located closest to the light emitting layer 4 when a plurality of electron transporting layers 5 are provided. As the electron transport material (also serving as a hole blocking material) used for the electron transport layer 5), any material can be used as long as it has a function of transmitting (transporting) electrons injected from the cathode 6 to the light emitting layer 4. Can be used. For example, as the electron transport material, any one of known compounds used in conventional organic EL elements can be appropriately selected and used.

  More specifically, for example, a metal complex such as a fluorene derivative, a carbazole derivative, an azacarbazole derivative, an oxadiazole derivative, a trizole derivative, a silole derivative, a pyridine derivative, a pyrimidine derivative, or an 8-quinolinol derivative is used as the electron transport material. be able to. As other electron transport materials, for example, metal phthalocyanine or metal free phthalocyanine, or a compound in which the terminal group thereof is substituted with an alkyl group or a sulfonic acid group can be used.

  In this embodiment, the electron transport layer 5 may be doped with an impurity as a guest material to form the electron transport layer 5 having a high n property (electron rich). Specific examples of the electron transport layer 5 having such a configuration are disclosed in, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, 2001-102175, J. Pat. Appl. Phys. , 95, 5773 (2004). Specifically, an organic alkali metal salt can be used as the guest material (dope material).

  When an alkali metal salt of an organic substance is used as a doping material, the kind of the organic substance is arbitrary. For example, formate, acetate, propionate, butyrate, valerate, caprate, enanthate, caprylic acid Salt, oxalate, malonate, succinate, benzoate, phthalate, isophthalate, terephthalate, salicylate, pyruvate, lactate, malate, adipate, mesylate A compound such as a salt, a tosylate, and a benzenesulfonate can be used as the organic substance. Among these, formate, acetate, propionate, butyrate, valerate, caprate, enanthate, caprylate, oxalate, malonate, succinate, or benzoate It is preferable to use acid salts as organic substances. More preferable organic substances are aliphatic carboxylic acids such as formate, acetate, propionate and butyrate. When this aliphatic carboxylic acid is used, the number of carbon atoms is preferably 4 or less. The most preferable compound as the organic substance is acetate.

  Moreover, although the kind of alkali metal which comprises the alkali metal salt of organic substance is arbitrary, Li, Na, K, or Cs can be used, for example. Among these alkali metals, a preferable alkali metal is K or Cs, and a more preferable alkali metal is Cs.

  Therefore, the alkali metal salt of the organic substance that can be used as the doping material of the electron transport layer 5 is a compound in which the organic substance and the alkali metal are combined. Specifically, as the doping material, for example, formic acid Li, formic acid K, formic acid Na, formic acid Cs, acetic acid Li, acetic acid K, sodium acetate, acetic acid Cs, propionic acid Li, propionic acid Na, propionic acid K, propionic acid Cs , Oxalic acid Li, oxalic acid Na, oxalic acid K, oxalic acid Cs, malonic acid Li, malonic acid Na, malonic acid K, malonic acid Cs, succinic acid Li, succinic acid Na, succinic acid K, succinic acid Cs, benzoic acid Acid Li, sodium benzoate, benzoic acid K, or benzoic acid Cs can be used. Among these, Li-acetate, K-acetate, Na-acetate, or Cs-acetate is a preferred dopant, and the most preferred dope is Cs-acetate. In addition, preferable content of these dope materials is about 1.5-35 mass% with respect to the electron carrying layer 5 to which a dope material is added, and more preferable content is about 3-25 mass%. The most preferable content is about 5 to 15% by mass.

(2) Electron Injection Layer In the organic EL element 10 of the present embodiment, although not shown in FIG. 1, electron injection is performed between the cathode 6 and the light emitting layer 4 or between the cathode 6 and the electron transport layer 5. A layer (electronic buffer layer) may be provided. Similar to the hole injection layer, the electron injection layer is a layer provided between the cathode and the organic layer compound layer in order to lower the driving voltage of the organic EL element 10 and improve the light emission luminance.

  Here, a detailed description of the configuration of the electron injection layer is omitted, but for example, “Organic EL element and its industrialization front line” (issued by NTT, Inc. on November 30, 1998) The structure of the electron injection layer is described in detail in the chapter “Electrode Material” (pages 123-166).

[cathode]
The cathode 6 is an electrode film that supplies (injects) electrons to the light-emitting layer 4, and usually has a small work function (2 eV or less), such as a metal (electron-injecting metal), an alloy, an electrically conductive compound, and It is formed with electrode materials, such as these mixtures.

Specifically, in the organic EL element 10, when light is extracted from the cathode 6 side, the cathode 6 can be formed of a light-transmissive electrode material, for example, as with the anode 2. In this embodiment, it is preferable to use IDIXO (registered trademark: In ₂ O ₃ —ZnO), which is an amorphous transparent electrode material, as a material for forming the cathode 6.

On the other hand, in the organic EL element 10, when light is not extracted from the cathode 6 side (when light is extracted from the anode 2), the cathode 6 is, for example, aluminum, sodium, sodium-potassium alloy, magnesium, lithium, magnesium / Formed with non-transparent electrode materials such as copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, indium, lithium / aluminum mixture, rare earth metal, etc. be able to. However, in this embodiment, after forming these electrode materials with a thickness of about 1 to 20 nm, a layer made of the transparent electrode material described in the anode 2 is formed on the thin film to constitute the cathode 6. May be. In this case, the cathode 6 can be made transparent or semi-transparent, and light can be extracted also from the cathode 6 side.

  The cathode 6 having the above-described configuration can be formed on the electron transport layer 5 by a technique such as vapor deposition or sputtering.

[Gas barrier layer]
The gas barrier layer 7 is provided mainly for preventing water vapor from entering the organic compound layer composed of the hole transport layer 3, the light emitting layer 4, and the electron transport layer 5 (for moisture prevention), as shown in FIG. And an organic compound layer comprising the hole transport layer 3, the light emitting layer 4 and the electron transport layer 5, and the anode 2 and the cathode 6.

As a material for forming the gas barrier layer 7, any material can be used as long as the material can cause deterioration of the organic EL element 10 and can suppress, for example, moisture and oxygen from entering the organic EL element 10. The gas barrier layer 7 is preferably composed of a film having a water vapor permeability of about 0.01 g / [m ² · day · atm] or less.

  Examples of the material for forming the gas barrier layer 7 having the above-described characteristics include a photo-curing sealant, a thermosetting sealant, a moisture-curing sealant such as 2-cyanoacrylate, heat such as an epoxy-based material, and the like. Sealing agents such as a chemical curing type (two-component mixed) sealing agent and a cationic curing type ultraviolet curing epoxy resin sealing agent can be used.

  Further, the gas barrier layer 7 can be formed of a film made of an inorganic material such as silicon oxide, silicon dioxide, silicon nitride, silicon oxynitride. In the present embodiment, it is particularly preferable that the gas barrier layer 7 is composed of a single film of silicon nitride or silicon oxynitride. Further, in order to improve the fragility of the gas barrier layer 7, the gas barrier layer 7 may be constituted by a hybrid film in which a film made of the inorganic material and a film made of an organic material are laminated. In this case, the stacking order of the film made of an inorganic material and the film made of an organic material is arbitrary.

  As a method for forming the gas barrier layer 7 described above, any method can be used as long as the method can form the gas barrier layer 7 on the cathode 6. For example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma polymerization method, plasma CVD method, laser CVD method, thermal CVD A method such as a method or a coating method can be used.

[Light diffusing resin layer]
The light diffusing resin layer 12 includes a resin layer (base material layer) formed of a thermoplastic resin, and a plurality of diffusion portions having a refractive index different from the refractive index of the resin layer and dispersed inside the resin layer. And have. When the diffusing portion is dispersed in the base material layer in this way, the light emitted from the light emitting layer 4 to the light diffusing resin layer 12 is caused by the difference in refractive index between the base material layer and the diffusing portion. 12 is diffused within. In the present embodiment, the light diffusing resin layer 12 not only functions as a diffusion layer, but also serves as an adhesive layer when the organic EL element body 11 and the sealing substrate 13 are bonded and sealed together. Also works.

  The light diffusing resin layer 12 having the above-described configuration is obtained by, for example, heat-treating a base material layer formed of a light-transmitting thermoplastic resin under a predetermined condition, so that a plurality of microcrystalline regions ( It can be produced by dispersing and generating a diffusion portion having a refractive index different from that of the base material layer. The thermoplastic resin produced by dispersing the microcrystalline regions in the thermoplastic resin layer by the heat treatment is hereinafter referred to as “crystalline thermoplastic resin”.

  The light diffusing resin layer 12 produced as described above becomes clouded. The cloudiness range in the light diffusing resin layer 12 can be set as appropriate by adjusting the heating range, and the cloudiness degree (light diffusion degree) is determined based on the heating conditions (for example, heating temperature, heating time, etc.). It can be set by adjusting. That is, when a crystalline thermoplastic resin is used as the base material of the light diffusing resin layer 12, by appropriately adjusting the heating range and / or heating conditions when forming the light diffusing resin layer 12, The cloudiness range and / or cloudiness degree (light diffusion range and / or diffusion degree) can be freely designed. The heating conditions (for example, heating temperature, heating time, etc.) are arbitrary as long as the light diffusing function can be added to the light diffusing resin layer 12 and the organic EL element 10 is not broken. Can be set in the condition.

  Note that the method for producing the light diffusing resin layer 12 is not limited to the above-described example, and a method capable of generating a diffusing portion having a refractive index different from the refractive index of the base material layer while being dispersed in the base material layer. Any method can be used. For example, a thermoplastic resin containing a diffusion component having a refractive index different from the refractive index of the base material is prepared, and the thermoplastic resin layer is provided on the sealing substrate 13 to produce the light diffusing resin layer 12. May be. Further, for example, a light diffusing resin is obtained by introducing (doping) a diffusion component having a refractive index different from the refractive index of the base material into the base material layer of the thermoplastic resin provided on the sealing substrate 13 from the outside. Layer 12 may be made.

  As the crystalline thermoplastic resin having the above-described characteristics, a thermoplastic resin material having a melt flow rate of about 5 to 20 g / 10 min is preferable, and in particular, a heat having a melt flow rate of about 6 to 15 g / 10 min or less. A plastic resin material is preferred. However, the “melt flow rate” here is a value measured by a method based on JIS-K7210.

  In the present embodiment, any crystalline thermoplastic resin can be used as long as it is a crystalline thermoplastic resin having a melt flow rate in the above numerical range. Specifically, examples of the crystalline thermoplastic resin include low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), medium density polyethylene, unstretched polypropylene (CPP), and stretched polypropylene. Resin materials such as (OPP), polyethylene terephthalate (PET), ethylene-vinyl acetate copolymer (EVOH), ethylene-acrylic acid copolymer, and ethylene-methacrylic acid copolymer can be used. Among these crystalline thermoplastic resins, it is particularly preferable to use a crystalline thermoplastic resin containing an ethylene-methacrylic acid copolymer.

  The crystalline thermoplastic resin is appropriately selected in consideration of, for example, the compatibility of adhesion between the light diffusing resin layer 12 and the sealing base material 13 adjacent thereto, the gas barrier layer 7 and the element substrate 1. Can do. Moreover, the usage form of crystalline thermoplastic resin can be suitably selected from types, such as a fusion | melting type and a sheet-like type. Therefore, it is preferable to use an apparatus that can appropriately cope with the type of use form of the selected crystalline thermoplastic resin as a curing apparatus (heat treatment apparatus) for the crystalline thermoplastic resin.

[Sealing substrate]
The sealing base material 13 is comprised with the plate-shaped (film-shaped) member which has a light transmittance. As the sealing substrate 13, a plate-like member having a flat surface may be used, or a plate-like member having irregularities formed on the surface may be used.

  The sealing substrate 13 can be formed of a transparent material such as glass or plastic. In particular, it is preferable that the sealing substrate 13 is made of a glass substrate, a quartz substrate, or a flexible sealing member. In addition, as a flexible sealing member, members, such as a multilayer film member which laminated | stacked the resin layer and the barrier layer (coating consisting of an inorganic substance), and thin film glass which has flexibility, for example can be used.

  When the sealing substrate 13 is configured by a flexible sealing member, it is preferable to use a flexible sealing member having a multilayer structure in which a resin layer and a barrier layer are laminated. Note that the thickness of the flexible sealing member is preferably about 10 to 300 μm in consideration of characteristics such as handling at the time of manufacture, tensile strength, and stress cracking resistance of the barrier layer. However, the “thickness” here is an average thickness of the flexible sealing member. For example, using a micrometer, the thickness is 10 respectively along the longitudinal direction and the width direction of the flexible sealing member. It is the average value of the thickness measured at about locations.

  When the sealing substrate 13 is formed of a flexible sealing member, the amount of moisture in the flexible sealing member is, for example, crystallization of an organic compound layer generated by moisture brought in by the flexible sealing member. In consideration of suppression of dark spots, suppression of dark spots generated due to peeling of the cathode 6, extension of the lifetime of the organic EL element 10, etc., it is preferably about 1.0% or less. However, the “water content” referred to here is a value measured by a technique based on ASTM (American Society for Testing and Materials) -D570.

  The resin layer constituting the flexible sealing member is, for example, ethylene tetrafluoroethyl copolymer (ETFE), high density polyethylene (HDPE), expanded polypropylene (OPP), polystyrene (PS), polymethyl methacrylate (PMMA). , Made of thermoplastic resin used for general packaging film such as stretched nylon (ONy), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polyimide, polyether styrene (PES) be able to. In addition, as a thermoplastic resin film, if necessary, a multilayer film produced by co-extrusion of different films, a multilayer film produced by laminating a plurality of films with different stretching angles, etc. It can also be used. Moreover, when producing such a multilayer film, in order to obtain the physical properties required for the flexible sealing member, it is preferable to combine them in consideration of physical properties such as the density and molecular weight distribution of each film used.

Further, the water vapor permeability of the barrier layer constituting the flexible sealing member is, for example, suppressed crystallization of the organic compound layer, suppressed dark spots caused by peeling of the cathode 6, and the like of the organic EL element 10. In consideration of prolonging the life, etc., it is preferably about 0.01 g / [m ² · day · atm] or less. In addition, the oxygen permeability of the barrier layer is, for example, in consideration of suppression of crystallization of the organic compound layer, suppression of dark spots generated due to peeling of the cathode 6, and extension of the lifetime of the organic EL element 10, etc. It is preferably about 0.01 cm ³ / [m ² · day · atm] or less.

  As a material for forming the barrier layer, any material can be used as long as it has the above-described water vapor permeability and oxygen permeability. For example, the barrier layer can be composed of a film made of an inorganic material such as silicon oxide, silicon dioxide, or silicon nitride. In order to improve the brittleness of the barrier layer, it is more preferable that the barrier layer is composed of a hybrid film (multilayer film) obtained by laminating the film made of the inorganic material and the film made of the organic material. In this case, the order of laminating the film made of an inorganic material and the film made of an organic material is arbitrary, but it is preferable to laminate a plurality of both alternately.

  In addition, as a method for forming the barrier layer, any method can be used as long as the barrier layer can be formed on the resin layer. For example, vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma polymerization method (see JP 2004-68143 A), Techniques such as plasma CVD, laser CVD, thermal CVD, and coating can be used. Among these barrier layer formation methods, it is particularly preferable to form the barrier layer using an atmospheric pressure plasma polymerization method.

[Usage]
The organic EL element 10 of the present embodiment described above can be applied to uses such as a display device, a display, and a light emitting light source.

  Applications of light emitting light sources include, for example, household lighting, interior lighting, clock and liquid crystal display backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light There are a wide range of uses such as light sources for sensors and general household appliances that require a display device. In particular, the organic EL element 10 of the present embodiment is suitable for applications that require white light, such as a backlight of a liquid crystal display device combining a color filter and an organic EL element, or a light source for illumination.

<2. Manufacturing method of organic EL element>
Next, an example of a method for producing the organic EL element 10 of the present embodiment will be briefly described with reference to FIGS. 2 to 5 are schematic cross-sectional views of members produced in each manufacturing process.

  First, in the present embodiment, an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, a cathode 6, and a gas barrier layer 7 are laminated in this order on the element substrate 1 to obtain an organic EL element. The main body 11 (element main body) is produced (state shown in FIG. 2). At this time, each electrode and each layer are formed by the method described in the description of each part.

  In addition, in the manufacturing process of the organic EL element body 11, the electrodes and / or layers may be formed as necessary by using a method using a metal mask or an inkjet printing method, for example. Each layer may be patterned. For example, only the electrode may be patterned, or both the electrode and the light emitting layer may be patterned. Further, for example, all layers constituting the organic EL element 10 may be patterned.

  Next, a crystalline thermoplastic resin layer serving as a base material of the light diffusing resin layer 12 is provided on the sealing base material 13 to form a base material layer 12a on the sealing base material 13 (state of FIG. 3). ). Note that the thickness of the base material layer 12a can be appropriately set according to conditions such as the type of the crystalline thermoplastic resin and the thickness of the organic EL element 10, for example. In this embodiment, when the sealing base material 13 and the organic EL element main body 11 are bonded together, the distance (interval in the thickness direction) between the sealing base material 13 and the element substrate 1 is about 40 μm. Thus, the thickness of the base material layer 12a is adjusted.

  In addition, the order of the process (process of FIG. 2) which produces the organic EL element main-body part 11 and the process (process of FIG. 3) which forms the base material layer 12a on the sealing base material 13 is arbitrary, The former This step may be performed first, or the latter step may be performed first. Moreover, you may perform both processes in parallel.

  Next, the organic EL element body 11 and the sealing substrate 13 are pasted so that the gas barrier layer 7 of the organic EL element body 11 and the base material layer 12a provided on the sealing substrate 13 face each other. Match (state of FIG. 4). At this time, while heating at a predetermined temperature, the organic EL element body 11 and the sealing substrate 13 are bonded together by pressing with a pressure in the range of about 0.5 to 100 Pa, for example. That is, in this embodiment, the organic EL element main body 11 and the sealing substrate 13 are bonded together by thermocompression bonding. In addition, it is preferable to implement this bonding process under a reduced pressure atmosphere. Thereby, it is possible to prevent bubbles from remaining inside the organic EL element 10 when the organic EL element body 11 (element substrate 1) and the sealing substrate 13 are bonded together.

  Next, a predetermined heat treatment is performed on the thermocompression-bonded member (state shown in FIG. 5). In this heat treatment step, a plurality of diffusion portions (for example, microcrystalline diffusion regions) having a refractive index different from the refractive index of the base material layer 12a are dispersed and generated in the base material layer 12a. Thus, the light diffusing resin layer 12 is formed (state shown in FIG. 1). In addition, the formation method of the light diffusable resin layer 12 is not limited to this example, For example, even if it forms the light diffusable resin layer 12 by adjusting suitably the heating temperature of the thermocompression-bonding process in the said bonding process. Good.

  In the present embodiment, the organic EL element 10 is produced as described above. In the manufacturing method of the organic EL element 10 of the present embodiment, in the heat treatment step after the bonding step, the heating range and / or the heating conditions are adjusted as appropriate, so that the diffusion range of the diffusion portion and / or the light diffusion degree is adjusted. It can be set freely.

  In addition, although the example of this embodiment demonstrated the example which forms the light diffusable resin layer 12 between the cathode 6 and the sealing base material 13, this invention is not limited to this. When taking out the light emitted from the light emitting layer 4 from the anode 2 side, a light diffusing resin layer 12 is formed between the anode 2 and the element substrate 1, and then various kinds of light are formed on the light diffusing resin layer 12. You may form an electrode and a layer, and a sealing member sequentially.

<3. Light emitting operation of organic EL element (light extraction operation)>
Next, the light emission operation and the light extraction operation in the organic EL element 10 of the present embodiment will be described. First, when a voltage is applied between the anode 2 and the cathode 6, holes are injected from the anode 2 into the light emitting layer 4 through the hole transport layer 3, and the light emitting layer 4 from the cathode 6 through the electron transport layer 5 is injected. Electrons are injected into the. Next, the holes and electrons injected into the light emitting layer 4 are recombined in the light emitting layer 4, thereby generating light emission.

  Next, the light emitted from the light emitting layer 4 toward the cathode 6 enters the light diffusing resin layer 12 through the gas barrier layer 7. At this time, the light diffusing resin layer 12 has microcrystalline diffusing portions dispersed in a different refractive index from the base material layer 12a, so that the light incident on the light diffusing resin layer 12 is It is diffused by the diffusion unit. Then, the light diffused by the light diffusing resin layer 12 is incident on the sealing substrate 13.

  A part of the diffused light incident on the sealing substrate 13 is emitted from the surface of the sealing substrate 13 to the outside. On the other hand, the remaining part of the diffused light incident on the sealing substrate 13 is totally reflected at the interface between the sealing substrate 13 and the outside, and is confined in the organic EL element 10 or is organic. The light is emitted from the side of the EL element 10. In the organic EL element 10 of the present embodiment, the light emitted from the light emitting layer 4 is taken out from the sealing substrate 13 side as described above.

  In the organic EL element 10 of the present embodiment, as described above, the light emitted from the light emitting layer 4 is diffused by the light diffusing resin layer 12 before entering the sealing substrate 13. That is, in this embodiment, the light diffused by the light diffusing resin layer 12 (diffused light) is incident on the sealing substrate 13. Therefore, in this case, compared with the case where the light diffusing resin layer 12 is not provided, the light component totally reflected at the interface between the sealing substrate 13 and the outside can be reduced. As a result, in this embodiment, compared to the case where the light diffusing resin layer 12 is not provided, the amount of light emitted (extracted) from the surface (light emitting surface) of the sealing substrate 13 to the outside is increased. And the luminous efficiency can be improved.

  In addition, in the conventional organic EL element, a technique of providing a diffusion sheet on the outer surface of the sealing substrate has also been proposed, but in this configuration, light emitted from the sealing substrate 13 (the sealing substrate and the outside) The light diffusion process is applied to the light component excluding the light component totally reflected at the interface with the light source. Therefore, in this configuration, the light component totally reflected at the interface between the sealing substrate and the outside cannot be reduced. On the other hand, in the present embodiment, as described above, light is diffused before entering the sealing base material 13, so that the light component totally reflected at the interface between the sealing base material 13 and the outside is reduced. Can be made. Therefore, in the organic EL element 10 of the present embodiment, the luminous efficiency can be improved as compared with the conventional organic EL element in which the diffusion sheet is provided on the outer surface of the sealing substrate.

  Furthermore, as will be described in the following examples, a light diffusing resin layer 12 having both an adhesion function and a light diffusion function between the organic EL element body 11 and the sealing substrate 13 as in the present embodiment. Is provided, not only the effect of improving the light emission efficiency but also the organic EL element 10 having a small change in the front luminance with time, that is, the light emission stability can be obtained.

  In this embodiment, since the light diffusing resin layer 12 serves both as an adhesive function and a light diffusing function, it is not necessary to separately provide a diffusion sheet on the outer surface of the sealing substrate as in the prior art. . Therefore, in the present embodiment, it is possible to provide the organic EL element 10 having a thinner and simpler configuration.

  As described above, in the organic EL element 10 of the present embodiment, the light diffusing resin layer 12 is provided between the organic EL element main body 11 (cathode 6) and the sealing substrate 13 to thereby provide a simpler configuration. In addition, the organic EL element 10 having excellent light emission characteristics can be obtained.

  In the present embodiment, the light diffusing function can be added to the light diffusing resin layer 12 only by subjecting the light diffusing resin layer 12 having an adhesion function to heat treatment under predetermined conditions. Furthermore, in this embodiment, the process of providing a diffusion sheet separately on the outer surface of the sealing substrate can be omitted. Therefore, in the present embodiment, the organic EL element 10 having excellent light emission performance can be manufactured by a simpler manufacturing process.

<4. Various Examples of Organic EL Elements>
Next, configurations of various examples of organic EL elements (organic EL panels) actually manufactured and evaluation of light emission characteristics performed on the organic EL elements of the various examples will be described.

[Example 1]
FIG. 6 shows a schematic cross-sectional view of the organic EL element produced in Example 1. The organic EL element 20 of Example 1 includes an organic EL element main body 21, a light diffusing resin layer 22, and a sealing substrate 23. The organic EL element 20 of this example is configured by bonding an organic EL element body 21 and a sealing substrate 23 via a light diffusing resin layer 22.

  The organic EL element body 21 in this example includes an element substrate 31, an anode 32, a first hole transport layer 33, a second hole transport layer 34, a first light emitting layer 35, and a second light emitting layer 36. And an electron transport layer 37, an electron injection layer 38, a cathode 39, and a gas barrier layer 40. In this example, the anode 32, the first hole transport layer 33, the second hole transport layer 34, the first light emitting layer 35, the second light emitting layer 36, the electron transport layer 37, the electron injection are provided on the element substrate 31. The layer 38, the cathode 39, and the gas barrier layer 40 are laminated in this order.

  The organic EL element 20 in this example is a type of element that takes out light emitted from the light emitting layers (the first light emitting layer 35 and the second light emitting layer 36) from both sides of the anode 32 and the cathode 39, and will be described later. In addition, both the anode 32 and the cathode 39 are composed of transparent electrodes. The configuration (for example, material, dimensions, etc.) of each part of the organic EL element 20 and the manufacturing method of the organic EL element 20 are as follows.

(1) Sample 1001
First, an element substrate 31 made of a glass substrate (NH Techno Glass, NH45) having dimensions of 150 mm × 150 mm × 1.1 mm was prepared. Next, an ITO (transparent electrode material) having a thickness of 150 nm was formed on the element substrate 31 to form the anode 32. Next, patterning was performed on the anode 32 to form the anode 32 having a predetermined shape. Next, the element substrate 31 on which the anode 32 was formed was ultrasonically cleaned with isopropyl alcohol. Then, after the ultrasonically cleaned element substrate 31 was dried with dry nitrogen gas, UV ozone cleaning was performed on the element substrate 31 on which the anode 32 was formed for 5 minutes.

  Next, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PSS: manufactured by Bayer, Baytron P Al 4083) is added with pure water on the anode 32 (surface of the element substrate 31 on the anode 32 side). The solution diluted to mass% was applied by spin coating under conditions of 3000 rpm and 30 seconds. Thereafter, the applied solution was dried at 200 ° C. for 1 hour, thereby forming a first hole transport layer 33 having a thickness of 30 nm. PEDOT contained in the first hole transport layer 33 is represented by the following structural formula (1).

  Next, the element substrate 31 formed up to the first hole transport layer 33 is transferred to an atmosphere environment of nitrogen gas (grade G1). Next, in a nitrogen atmosphere, a solution obtained by dissolving 0.5% by mass of a hole transport material (HT-1 compound: molecular weight 80,000) represented by the following structural formula (2) in chlorobenzene was 1500 rpm for 30 seconds. It applied on the 1st positive hole transport layer 33 with the spin coat method on conditions. Thereafter, the applied solution was dried at 160 ° C. for 30 minutes, thereby forming a second hole transport layer 34 having a thickness of 30 nm.

Next, a first light-emitting layer composition (solvent: isopropyl acetate) containing a host compound, a blue dopant, a green dopant, and a red dopant in the following proportions is formed on the second hole transport layer 34 using an inkjet head. The discharge was injected. At this time, in this example, the first light-emitting layer composition was discharged so that the coating film thickness of the first light-emitting layer composition was 5.3 μm. Then, the element substrate 31 on which the first light emitting layer composition was applied was dried in a drying box at 120 ° C. for 10 minutes to form a first light emitting layer 35 having a thickness of 40 nm.
(First light emitting layer composition)
Host compound (HA): 0.69 parts by mass Blue dopant (D-66): 0.30 parts by mass Green dopant (D-67): 0.005 parts by mass Red dopant (D-80): 0.005 Part by mass Isopropyl acetate: 100 parts by mass

  The host compound (HA), blue dopant (D-66), green dopant (D-67), and red dopant (D-80) in the first light emitting layer composition are each represented by the following structural formula ( 3) to (6).

Next, a second light emitting layer composition (solvent: isopropyl acetate) containing a host compound, a blue dopant, a green dopant, and a red dopant in the following proportions is discharged and injected onto the first light emitting layer 35 using an inkjet head. did. At this time, in this example, the second light emitting layer composition was discharged so that the coating film thickness of the second light emitting layer composition was 5.3 μm. Then, the element substrate 31 coated with the second light emitting layer composition was dried in a drying box at 120 ° C. for 10 minutes to form a second light emitting layer 36 having a film thickness of 40 nm.
(Second light emitting layer composition)
Host compound (HA): 0.89 parts by mass Blue dopant (D-66): 0.10 parts by mass Green dopant (D-67): 0.005 parts by mass Red dopant (D-80): 0.005 Part by mass Isopropyl acetate: 100 parts by mass

  Next, a solution in which 30 mg of an electron transport material (ET-1 compound) represented by the following structural formula (7) is dissolved in 4 ml of tetrafluoropropanol (TFPO) is spin-coated at 1500 rpm for 30 seconds. It applied on the second light emitting layer 36. Thereafter, the applied solution was dried at 120 ° C. for 30 minutes, whereby an electron transport layer 37 having a thickness of 30 nm was formed.

Next, the element substrate 31 laminated up to the electron transport layer 37 was attached to a vacuum deposition apparatus without being exposed to the atmosphere. In addition, a molybdenum resistance heating boat filled with sodium fluoride and potassium fluoride, respectively, was attached to the vacuum chamber of the vacuum deposition apparatus. Thereafter, the vacuum chamber was depressurized to 4 × 10 ⁻⁵ Pa, and then current was passed through a resistance heating boat filled with sodium fluoride to heat the sodium fluoride, and a thin film of sodium fluoride was formed at 0.02 nm / second. It was formed on the electron transport layer 37 at a rate. In this example, a 1 nm-thick sodium fluoride thin film was formed. Next, an electric current was passed through a resistance heating boat filled with potassium fluoride to heat the potassium fluoride, and a thin film of potassium fluoride was formed on the thin film of sodium fluoride at a rate of 0.02 nm / second. In this example, a thin film of potassium fluoride having a thickness of 1.5 nm was formed. In this example, the electron injection layer 38 was formed on the electron transport layer 37 in this way.

Next, using a sputtering apparatus, a transparent electrode material IDIXO (registered trademark: In ₂ O ₃ —ZnO) was sputtered to form a cathode 39 having a thickness of 200 nm on the electron injection layer 38.

Next, silicon nitride (Si ₃ N ₄ ) was sputtered to form a gas barrier layer 40 having a thickness of 125 nm on the cathode 39. The sputtering conditions at this time are as follows. Silicon nitride (Si ₃ N ₄ ) was used as the target material, and the target shape was cylindrical. Further, the element substrate 31 laminated up to the cathode 39 was disposed so that the distance between the upper end of the target and the element substrate 31 was 7 cm. Further, argon gas containing 2% by volume of oxygen was used as the sputtering gas, and the gas pressure during sputtering was 1.33 × 10 ⁻² Pa. As the sputtering power source, an AC power source with a frequency of 13.56 MHz was used. When the film formation rate was monitored with a crystal resonator when the input power was 100 W, it was 0.1 nm / second.

  In this example, the organic EL element body 21 was produced as described above. In this example, a glass sealing substrate 23 provided with a crystalline thermoplastic resin layer (base material layer) made of an ethylene-methacrylic acid copolymer was prepared. Next, the organic EL element body 21 and the sealing substrate 23 are bonded so that the gas barrier layer 40 of the organic EL element body 21 and the base material layer provided on the sealing substrate 23 face each other. It was. And the bonding member was heat-pressed for 3 minutes from a vacuum laminator at 110 ° C.

  Next, the thermocompression-bonded member was heated with a hot plate at a constant temperature of 100 ° C. for 60 minutes, and then cooled at room temperature. In this example, the light diffusing resin layer 22 was prepared by dispersing the microcrystalline diffusion portion in the base material layer made of the crystalline thermoplastic resin by the heat treatment after the bonding. The heating temperature at this time can be set to any condition as long as the light diffusing function can be added to the light diffusing resin layer 12 and the organic EL element 20 is not broken. For example, the upper limit of the heating temperature can be about 200 ° C.

  In this example, the organic EL element 20 (sample 1001) was produced as described above. Moreover, in Example 1, various samples of the organic EL element 20 were produced by changing the heat treatment conditions after the above-described bonding in various ways. Specifically, the heating temperature after bonding was changed to 90 ° C., 110 ° C., or 120 ° C., and various samples (samples 1002 to 1004) of the organic EL element 20 were produced. Samples 1002 to 1004 were prepared in the same manner as the organic EL element 20 of Sample 1001 except that the heating temperature conditions after bonding were changed.

[Example 2]
In Example 2, the material for forming the gas barrier layer 40 in the organic EL device 20 (FIG. 6) of Example 1 was changed from silicon nitride (Si ₃ N ₄ ) to silicon oxynitride (SiON). In addition, except having changed the formation material of the gas barrier layer 40, it is the same as the sample 1002 (heating temperature after bonding: 90 degreeC) of the organic EL element 20 of the said Example 1, The organic EL element 20 of this example (Sample 1005) was manufactured.

  Moreover, in Example 2, the heating temperature after bonding was further changed to 130 ° C., and the organic EL element 20 (sample 1006) was produced.

[Example 3]
In Example 3, in the organic EL element 20 (FIG. 6) of Example 1 described above, the material for forming the gas barrier layer 40 was changed from silicon nitride (Si ₃ N ₄ ) to an ultraviolet curable epoxy resin. In this example, the gas barrier layer 40 was formed by applying an ultraviolet curable epoxy resin on the cathode 39 and then irradiating the ultraviolet ray to cure the ultraviolet curable epoxy resin. The organic EL device of this example is the same as the sample 1004 (heating temperature after bonding: 120 ° C.) of the organic EL device 20 of Example 1 except that the forming material and forming method of the gas barrier layer 40 are changed. 20 (sample 1007) was produced.

[Comparative Example 1]
In the comparative example 1, in order to compare with the organic EL element 20 of the said various Examples, the contact bonding layer provided between an organic EL element main-body part and a sealing base material was formed with the amorphous thermoplastic resin. The term “noncrystalline thermoplastic resin” as used herein refers to a resin in which a microcrystalline diffusion portion is not generated inside a base material layer made of an amorphous thermoplastic resin even when heat treatment is performed after bonding. Refers to material.

  Specifically, in Comparative Example 1, polyvinylidene chloride was used as the amorphous thermoplastic resin. In addition, except having changed the formation material of the contact bonding layer, it is the same as the sample 1004 (heating temperature after bonding: 120 degreeC) of the organic EL element 20 of the said Example 1, The organic EL element (sample) of this example 1008).

[Comparative Example 2]
In Comparative Example 2, adhesion provided between the organic EL element body 21 and the sealing substrate 23 in the organic EL element 20 of Example 3 (sample 1007 in which the gas barrier layer 40 is formed of an ultraviolet curable epoxy resin). The layer was formed from an amorphous thermoplastic resin. In Comparative Example 2, polyvinylidene chloride was used as the amorphous thermoplastic resin.

  In Comparative Example 2, an organic EL element (sample) was obtained in the same manner as Sample 1007 (heating temperature after bonding: 120 ° C.) of the organic EL element 20 of Example 3 except that the material for forming the adhesive layer was changed. 1009).

  In Comparative Example 2, the heating temperature after bonding was further changed to 80 ° C., and an organic EL element (sample 1010) was produced.

[Emission characteristics evaluation of organic EL elements]
With respect to samples 1001 to 1010 of various organic EL elements prepared in the various examples and various comparative examples, the light extraction efficiency and the temporal change in front luminance were examined.

  The light extraction efficiency was measured as follows. First, in a predetermined angle range (± 80 degrees in this example) with the normal direction of the light emitting surface of the organic EL element as a reference (0 degrees), the angle in the measurement direction is changed using an angle-luminance measuring device. The brightness in the angular direction was measured for each angle. A value obtained by integrating the luminance measured for each angle was defined as the light extraction efficiency.

  Further, the temporal change of the front luminance is the difference between the front luminance immediately after the production of the organic EL element 20 and the front luminance after leaving the organic EL element 20 for 240 hours in an environment of temperature 60 ° C. and humidity 90% RH ( Front luminance change) was determined and evaluated.

  The various evaluation results are shown in Table 1 below. In addition, the value of the light extraction efficiency and the front luminance change in the following Table 1 are relative values when the value of the sample 1008 of Comparative Example 1 is used as a reference (= 1.0).

  As is apparent from Table 1, the light extraction efficiency in the samples 1001 to 1007 of the organic EL elements 20 of the various examples is larger than that of the samples 1008 to 1010 of the organic EL elements of various comparative examples. From this, the luminous efficiency of the organic EL element 20 is improved by providing the light diffusing resin layer 22 between the organic EL element main body 21 and the sealing substrate 23 as in the above-described various embodiments. I understand that.

  Moreover, the value of the front luminance change of the samples 1001 to 1006 in the organic EL elements 20 of Examples 1 and 2 in which the gas barrier layer 40 is formed of a coating made of an inorganic material (SiN or SiON), and the gas barrier layer 40 is made of an inorganic material. When compared with that of the sample 1008 in the organic EL element of Comparative Example 1 configured with a coating (SiN), the former value is smaller than the latter value. Furthermore, the value of the front luminance change of the sample 1007 in the organic EL element 20 of Example 3 in which the gas barrier layer 40 is formed of a film made of an organic material (ultraviolet curable epoxy resin), and the gas barrier layer 40 is formed of a film made of an organic material. Comparing with the samples 1009 and 1010 in the organic EL element of Comparative Example 2 constructed, the former value becomes smaller than the latter value.

  That is, by providing the light diffusing resin layer 22 between the organic EL element main body 21 and the sealing substrate 23 as in the above-described various embodiments, the light emission stability with little change with time in the front luminance is small. It turns out that the outstanding organic EL element 20 is obtained. Further, as is apparent from Table 1, when the gas barrier layer 40 is formed of a coating made of an inorganic material (SiN or SiON), the value of the front luminance change is further reduced, and the light emission stability of the organic EL element 20 is improved. It turns out that it improves further.

  As is apparent from the evaluation results, by providing the light diffusing resin layer 22 between the organic EL element body 21 and the sealing substrate 23, the organic EL element 20 having excellent light emission efficiency and light emission stability. It can be seen that

DESCRIPTION OF SYMBOLS 1 ... Element substrate, 2 ... Anode, 3 ... Hole transport layer, 4 ... Light emitting layer, 5 ... Electron transport layer, 6 ... Cathode, 7 ... Gas barrier layer, 10 ... Organic EL element, 11 ... Organic EL element main-body part, 12 ... Light diffusing resin layer, 13 ... Sealing substrate

Claims (9)

An element substrate;
A first electrode formed on the element substrate;
An organic compound layer formed on the first electrode and including a light emitting layer;
A second electrode formed on the organic compound layer;
A sealing substrate formed on the second electrode;
A light diffusing resin layer that is formed between at least one of the element substrate and the first electrode and between the sealing base and the second electrode and diffuses light emitted from the light emitting layer; Prepared,
The light diffusing resin layer includes a base material layer formed of a thermoplastic resin, and a plurality of diffusion portions having a refractive index different from the refractive index of the base material layer and dispersed inside the base material layer. Have
The said diffusion part is an organic electroluminescent element which consists of a microcrystalline area | region of the said thermoplastic resin . The light diffusing resin layer is formed of a thermoplastic resin containing an ethylene-methacrylic acid polymer.
The organic electroluminescent element according to claim 1 . Furthermore, a gas barrier layer formed on the second electrode is provided,
The organic electroluminescent element according to claim 1, wherein the light diffusing resin layer is formed between the sealing substrate and the gas barrier layer. The gas barrier layer is composed of a silicon nitride film or a silicon oxynitride film.
The organic electroluminescent element according to claim 3 . The organic electroluminescent element as described in any one of Claims 1-4 in which the light inject | emitted from the said light emitting layer is radiated | emitted outside from the said sealing base material side. Forming a first electrode on an element substrate;
Forming an organic compound layer including a light emitting layer on the first electrode;
Forming a second electrode on the organic compound layer;
Forming a sealing substrate on the second electrode;
Forming a light-diffusing resin layer that diffuses light emitted from the light-emitting layer between at least one of the element substrate and the first electrode and between the sealing substrate and the second electrode; Including
Forming the light diffusing resin layer,
Forming a base material layer of the light diffusing resin layer on the sealing substrate with a thermoplastic resin;
The base electrode on the sealing substrate and the second electrode of the element main body configured by laminating the first electrode, the organic compound layer, and the second electrode in this order on the element substrate. Bonding the element body and the sealing substrate so that the layers face each other;
A method for producing an organic electroluminescent element , comprising: heating the bonded element main body and the sealing substrate to generate a microcrystalline region in the thermoplastic resin of the base material layer . The bonded element body and the sealing substrate are heated at a temperature of 90 ° C. or higher.
The manufacturing method of the organic electroluminescent element of Claim 6 . The bonded element body and the sealing substrate are heated at a temperature of 110 ° C. or higher.
The manufacturing method of the organic electroluminescent element of Claim 7 . And forming a gas barrier layer on the second electrode.
The manufacturing method of the organic electroluminescent element as described in any one of Claims 6-8 .

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