JP2007005138A - Organic el element and thin organic electroluminescent panel using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin organic EL panel with a sealing performance equivalent to or superior to an organic EL panel using glass with a concave part as a sealing substrate, of low cost, high strength, and high heat conduction. <P>SOLUTION: The organic EL element, provided with a substrate, transparent electrode, shadow mask, cathode-separating wall, organic EL layer, reflective electrode, inorganic protection layer, and moisture absorption layer, has its inorganic protection layer formed so as to cover at least side faces of the organic EL layer and side faces as well as a top face of the reflective electrode, and its moisture absorption layer formed at least on the inorganic protection layer. Further, an adhesive is filled between the element and the sealing substrate to seal the organic EL panel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic EL element and a thin organic EL panel using the same. More specifically, the present invention provides a thinner and lower cost organic EL panel than the conventional organic EL panel provided with a sealing substrate provided with a recess and a hygroscopic agent, and The present invention relates to providing an organic EL element applicable as a component of a panel.

  As an example of a light-emitting element that can be applied to a display device, an organic electroluminescence element (hereinafter, referred to as “organic EL element”) having a thin film laminated structure of an organic compound is known. Regarding organic EL elements, in 1987, Eastman Kodak's C.I. W. Since Tang et al. Announced the organic EL element having a two-layer structure that realizes high-efficiency light emission, various organic EL elements have been developed so far, and some of them have already been put into practical use.

  However, the organic EL element has a very short shelf life and operating life because the organic EL layer and the reflective electrode constituting the element deteriorate due to the influence of oxygen, moisture, etc. existing in the atmosphere. I have a problem. Therefore, in order to solve such a problem, the organic EL element is sealed with glass or a metal can so as to prevent entry of moisture and oxygen from the atmosphere. Of these, glass is often used. This is because glass does not transmit moisture, and the linear expansion coefficient matches that of a glass substrate used as a transparent substrate for organic EL elements. This is because it has the advantage that it is possible to suppress the occurrence of.

  More specifically, in the case of a bottom emission type organic EL panel as shown in FIGS. 1 and 2, first, an organic EL element applied to the panel is colored on a transparent glass substrate 11, for example. It is formed by laminating the laminated film 12 of organic EL elements including the conversion filter layer 21, the transparent electrode 22, the shadow mask 23, the organic EL layer 25, the reflective electrode 26, and the like. Here, the shadow mask 23 is formed on the entire surface of the transparent substrate 11 and the transparent electrode 22 excluding openings at positions corresponding to a plurality of light emitting portions of the organic EL element. In addition, since the organic EL layer 25 is made of an organic material, there is a possibility that the organic EL layer 25 may be deteriorated when a stripe shape is formed by etching after the reflective electrode 26 is formed. Therefore, it is necessary to form the stripe-shaped organic EL layer 25 and the reflective electrode 26 without causing such deterioration. As one of such methods, there is a method using a cathode separation wall 24. In this method, a cathode separation wall 24 having a cross-sectional shape as shown in FIG. 2 is formed by a photolithography method using a resist material in a direction orthogonal to the transparent electrode 22, and then the organic EL layer 25 in a vacuum evaporation apparatus. In this method, the stripe-shaped organic EL layer 25 and the reflective electrode 26 are formed by sequentially vapor-depositing the component and the reflective electrode 26 component.

  In the case of the organic EL element having the above configuration, there is a slight exposed portion (end portion 27) of the organic EL layer 25 that is not covered with the reflective electrode 26 as shown in FIG. Since the organic EL layer 25 is extremely sensitive to oxygen and moisture, when the organic EL element is exposed to the atmosphere in such a situation, moisture or the like enters through the end portion 27 and degrades the organic EL layer 25 in a short time. In the end, no light emission occurs. In addition to this, the reflective electrode 26 is oxidized by the invading oxygen, so that the conductivity and the reflectance are deteriorated. Therefore, in order to prevent such deterioration, generally, after the formation of the organic EL element, the organic EL element and the sealing substrate 14 are placed in a chamber in which oxygen and moisture are minimized as shown in FIG. As shown in b), they are joined and sealed with an ultraviolet curable adhesive 13 or the like. However, since the adhesive 13 used for joining is made of a polymer and has a low density, moisture and the like can enter and exit relatively easily. Therefore, in order to capture moisture entering from the gaps in the adhesive 13, the hygroscopic agent 15 is incorporated between the organic EL element and the sealing substrate 14. Further, at this time, in order to avoid contact between the substrate and the organic EL element laminated film 12 and to secure a gap for the moisture absorbent 15 to enter the sealing substrate 14, the organic EL element laminated film 12. In some cases, a substrate provided with a recess 19 at a position opposite to is used. Accordingly, the bonding portion of the sealing substrate 14 is brought close to the transparent substrate 11 of the organic EL element to a level of several μm without bringing the hygroscopic agent 15 into contact with the organic EL element (that is, the thickness of the adhesive 13 is reduced). Therefore, the sealing performance can be further enhanced as compared with an organic EL panel using flat glass for the sealing substrate 14 (see Patent Document 1).

JP 2004-235077 A

  According to the organic EL panel as shown in FIG. 1 to which the sealing substrate 14 provided with the recess 19 is applied, the sealing performance is greatly improved, but the depth of several hundred μm is formed in the sealing substrate 14 by sandblasting or etching. It is necessary to form the concave portion 19, which is very expensive compared to the case where flat glass is applied. Further, in the sealing substrate 14 provided with the recesses 19, the mechanical strength is lowered due to the influence of the thickness of the recesses 19 being reduced and the microcracks entered during the processing. In order to avoid this decrease in mechanical strength, a relatively thick glass (thickness: 0.7 mm to 2 mm) is generally used for the sealing substrate 14, but this reduces the thickness of the entire organic EL panel. The current situation is not possible.

  Further, when the organic EL panel emits light with high brightness, the temperature of the organic EL panel rises due to self-heating and the operation life is remarkably reduced. Therefore, it is necessary to efficiently dissipate the generated heat to the outside. However, in the organic EL panel having a sealing structure as shown in FIG. 1B, the inside (recessed portion 19) of the organic EL panel is hollow, and almost no heat conduction through it can be expected. Cannot solve the decrease in life.

  Therefore, an object of the present invention is to provide a sealing performance equal to or higher than that of a conventional organic EL panel using glass or the like in which a recess 19 is provided on the sealing substrate 14, while being inexpensive, high strength, and high thermal conductivity. Are to provide a practical and thin organic EL panel, and to provide an organic EL element applicable as a component of the organic EL panel.

  In order to solve the above-mentioned problems, the present invention provides the following inventions.

  The organic EL device of the present invention includes a transparent substrate, a transparent electrode formed in a stripe shape on the transparent substrate, a shadow mask formed so as to have a plurality of openings on the transparent electrode, and the transparent electrode A cathode separation wall formed between the direction perpendicular to the shadow mask and the opening of the shadow mask, and an organic EL layer including at least an organic light emitting layer formed in the shadow mask opening and on the cathode separation wall; An organic EL element having a reflective electrode formed on the organic EL layer, the inorganic protective layer formed to cover at least the side surface of the organic EL layer and the side surface and top surface of the reflective electrode, and at least the inorganic It further has a moisture absorption layer formed on the protective layer.

The organic EL panel of the present invention is an organic EL panel having the organic EL element, a sealing substrate, and an adhesive for joining the organic EL element and the sealing substrate.
The adhesive is filled with no gap between the organic EL element and the sealing substrate, and the organic EL element and the sealing substrate are bonded together.

  When flat glass is used instead of the glass provided with the recess as the sealing substrate, the thickness of the joint (adhesive layer) becomes relatively thick, so that the sealing performance generally decreases. However, according to the present invention, since the periphery of the organic EL layer and the reflective electrode is directly covered with the inorganic protective layer and the hygroscopic layer, the sealing performance is greatly improved. The decrease of can be covered. Therefore, according to the present invention, since flat glass can be used for the sealing substrate without reducing the sealing performance, compared to a conventional organic EL panel using glass or the like having a recess in the sealing substrate. An inexpensive organic EL panel can be provided. Moreover, the thickness of the substrate for sealing can be made thinner by using flat glass, and an organic EL panel thinner than the conventional organic EL panel can be provided.

  In addition, the organic EL panel of the present invention has a structure in which the space between the organic EL element constituting the panel and the sealing substrate is filled and fixed with an adhesive without any gap, so that the conventional organic EL panel having a gap in the panel is used. It is also possible to provide an organic EL panel that has higher strength and better heat dissipation performance than an EL panel. At this time, deterioration of the organic EL element due to moisture and gas components generated from the filled adhesive can be considered, but in the present invention, the organic EL layer and the reflective electrode are directly covered with the inorganic protective layer and the moisture absorbing layer. So you will not be affected by this.

  In addition, the organic EL panel of the present invention can realize a long shelf life and an operating life by improving the sealing performance and the heat dissipation performance as described above.

  Although the present invention has the above-described features, FIG. 3 shows one embodiment of the organic EL panel of the present invention. The organic EL panel of the present invention has a structure in which an adhesive 33 is filled between the organic EL element and the sealing substrate 34. Among these, the organic EL element includes a transparent substrate 11, a transparent electrode 22 formed in a stripe shape on the transparent substrate 11, and a shadow mask 23 formed so as to have a plurality of openings on the transparent electrode 22. A cathode separation wall 24 formed in a direction orthogonal to the transparent electrode 22 and between the openings of the shadow mask 23, and at least organic formed in the opening of the shadow mask 23 and on the cathode separation wall 24. An organic EL layer 25 including a light emitting layer, a reflective electrode 26 formed on the organic EL layer 25, and an inorganic layer formed so as to cover at least the side surface of the organic EL layer 25 and the side surface and top surface of the reflective electrode 26. The protective layer 31 and the hygroscopic layer 32 formed on at least the inorganic protective layer 31 are used. The organic EL panel of FIG. 3 further includes a color conversion filter layer 21 between the transparent substrate 11 and the transparent electrode 22.

  The transparent substrate 11 should be able to withstand the conditions (solvent, temperature, etc.) used for forming the layer to be laminated, and preferably has excellent dimensional stability. Preferred materials include resins such as glass, polyethylene terephthalate, polymethyl methacrylate. Alternatively, a flexible film formed from polyolefin, acrylic resin, polyester resin, polyimide resin, or the like may be used as the substrate.

  The color conversion filter layer 21 can be formed on the transparent substrate 11 as necessary. In this specification, the color conversion filter layer 21 refers to a generic name of a color filter layer, a color conversion layer, and a laminate of a color filter layer and a color conversion layer. In order to enable full color display, an independent color conversion filter layer 21 that emits light of at least a blue (B) region, a green (G) region, and a red (R) region is provided. If the organic EL layer 25 itself can emit light including the R, G, and B regions, the color conversion filter layer 21 can be configured with only a color filter layer.

  The color filter layer is a layer that transmits only light in a desired wavelength range. In the case of adopting a laminated structure with the color conversion layer, the color filter layer is effective in improving the color purity of the light subjected to wavelength distribution conversion in the color conversion layer. For example, the color filter layer may be formed using a commercially available color filter material for liquid crystal (such as a color mosaic manufactured by Fuji Film Arch).

  The color conversion layer absorbs light in the near ultraviolet region or visible region emitted from the organic EL layer 25, particularly light in the blue or blue-green region, and emits visible light having a different wavelength. Each of the RGB color conversion layers includes at least an organic fluorescent dye and a matrix resin.

1) Organic fluorescent dye In the present invention, preferably, at least one fluorescent dye emitting fluorescence in the red region is used, and further combined with one or more fluorescent dyes emitting green region fluorescence. This is because when the organic EL layer 25 that emits light in the blue to blue-green region is used as the light source, if light from the organic EL layer 25 is passed through a simple red filter to obtain light in the red region, This is because the output light becomes extremely dark due to the small amount of light of the wavelength.

  Therefore, by converting the light in the blue or blue-green region from the organic EL layer 25 into the light in the red region by the fluorescent dye, the light in the red region having sufficient intensity can be output. Examples of fluorescent dyes that absorb light in the blue to blue-green region emitted from the luminescent material and emit fluorescence in the red region include rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, sulforhodamine, basic violet 11 Pyridine dyes such as rhodamine dyes such as basic red 2, cyanine dyes, 1-ethyl-2- [4- (p-dimethylaminophenyl) -1,3-butadienyl] -pyridinium perchlorate (pyridine 1) Or oxazine dyes. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used if they are fluorescent.

  Examples of fluorescent dyes that absorb blue to blue-green light emitted from a light emitter and emit green light include 3- (2′-benzothiazolyl) -7-diethylamino-coumarin (coumarin 6), 3- (2′-Benzimidazolyl) -7-diethylamino-coumarin (coumarin 7), 3- (2′-N-methylbenzimidazolyl) -7-diethylamino-coumarin (coumarin 30), 2,3,5,6-1H, 4H -Coumarin-based dyes such as tetrahydro-8-trifluoromethylquinolidine (9,9a, 1-gh) coumarin (coumarin 153), or basic yellow 51 which is a coumarin dye-based dye, solvent yellow 11, solvent yellow 116 And naphthalimide dyes. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used if they are fluorescent.

  Furthermore, regarding the light in the blue region, a blue conversion layer that performs wavelength distribution conversion of near-ultraviolet light or blue-green light emitted from the organic EL layer 25 and outputs blue light may be included. However, when the organic EL layer 25 emits blue to blue-green light, it is preferable to use only the blue color filter layer.

  When the organic EL layer 25 emits white light, a desired color can be obtained only by the color filter layer, but by using each color conversion layer, light emission of the three primary colors can be performed with higher efficiency than in the case of only the color filter layer. Can be obtained.

  The organic fluorescent dye used in the present invention is a polymethacrylate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin, alkyd resin, aromatic sulfonamide resin, urea resin, melamine resin, benzoguanamine resin, and these resins. An organic fluorescent pigment may be obtained by kneading into a mixture or the like in advance to obtain a pigment. In addition, these organic fluorescent dyes and organic fluorescent pigments (in the present specification, the above two are collectively referred to as organic fluorescent dyes) may be used alone, or two or more of them may be used to adjust the hue of fluorescence. May be used in combination.

  The color conversion layer of the present invention contains 0.01 to 5% by mass, more preferably 0.1 to 2% by mass of an organic fluorescent dye based on the weight of the color conversion layer. By using the organic fluorescent dye in the content range, it is possible to perform sufficient wavelength conversion without being accompanied by a decrease in color conversion efficiency due to effects such as concentration quenching.

2) Matrix resin Next, the matrix resin used in the color conversion layer of the present invention generates radical species or ion species by light and / or heat treatment of a photocurable or photothermal combination type curable resin (resist). Polymerized or cross-linked and insoluble and infusible. In order to perform patterning of the color conversion layer, it is desirable that the photocurable or photothermal combination type curable resin is soluble in an organic solvent or an alkaline solution in an unexposed state.

  Specifically, the matrix resin is obtained by subjecting a composition film comprising (1) an acrylic polyfunctional monomer and oligomer having a plurality of acryloyl groups and methacryloyl groups and light or heat polymerization initiator to light or heat treatment, Or a polymer obtained by generating thermal radicals, (2) a composition comprising a polyvinylcinnamic acid ester and a sensitizer dimerized by light or heat treatment, and (3) a chain or cyclic olefin A composition film composed of bisazide is irradiated with light or heat to generate nitrene and crosslinked with olefin, and (4) a composition film composed of a monomer having an epoxy group and an acid generator is subjected to light or heat treatment, Including those polymerized by generating an acid (cation). In particular, a polymer obtained by polymerizing a composition comprising the acrylic polyfunctional monomer and oligomer (1) and light or a thermal polymerization initiator is preferred. This is because the composition can be patterned with high definition and has high reliability such as solvent resistance and heat resistance after polymerization.

  The photopolymerization initiator, sensitizer, and acid generator that can be used in the present invention are preferably those that initiate polymerization by light having a wavelength that is not absorbed by the fluorescent conversion dye contained therein. In the color conversion layer of the present invention, when the resin itself in the photocurable or photothermal combination curable resin can be polymerized by light or heat, a photopolymerization initiator and a thermal polymerization initiator are not added. It is also possible.

  A matrix resin (color conversion layer) is formed by applying a solution or dispersion containing a photocurable or photothermal combination curable resin, an organic fluorescent dye and an additive on a support substrate, and forming a resin layer, and It is formed by polymerizing a desired portion of a photocurable or photothermal combination type curable resin by exposure. Patterning is performed after exposing the desired portion to insolubilize the photocurable or photothermal combination type curable resin. The patterning can be performed by a conventional method such as removing the resin in the unexposed portion using an organic solvent or an alkali solution in which the resin in the unexposed portion is dissolved or dispersed.

3) Configuration Regarding red, it may be formed of only a red color conversion layer. However, when sufficient color purity cannot be obtained only by conversion with a fluorescent dye, a laminate of a red conversion layer and a color filter layer may be used. When the color filter layer is used in combination, the thickness of the color filter layer is preferably 1 to 2 μm.

  Moreover, about green, you may form only from a green conversion layer. However, when sufficient color purity cannot be obtained only by conversion with a fluorescent dye, a laminate of a green conversion layer and a color filter layer may be used. When the color filter layer is used in combination, the thickness of the color filter layer is preferably 1 to 2 μm.

  On the other hand, for blue, only the color filter layer can be used. When only the color filter layer is used, the thickness is preferably 1 to 17 μm.

  The color conversion layer can be formed by applying to a substrate using a spin coat method, a roll coat method, a cast method, a dip coat method, etc., and then patterning using a photolithographic method or the like. The thickness of the color conversion layer is preferably 5 to 15 μm.

  When the color conversion filter layer 21 is formed, the black matrix is applied to the substrate using a spin coating method, a roll coating method, a casting method, a dip coating method, or the like, in a region between the color conversion filter layers 21 corresponding to each color. Then, it is preferably formed by patterning using a photolithographic method or the like. As the black matrix material, a commercially available black matrix material for flat panel displays such as for liquid crystal can be used. By providing the black matrix, it is possible to prevent leakage of light to the color conversion filter layer 21 of the adjacent sub-pixel and obtain only a desired fluorescence conversion color without blur. You may provide a black mask around the area | region in which the color conversion filter layer 21 on the transparent substrate 11 is provided on the condition that sealing of the organic EL panel mentioned later is not prevented.

  Optionally, a smooth layer can be formed by a casting method, a spin coating method or a roll dip coating method so as to cover the color conversion filter layer 21. This smooth layer is preferably made of a polymer material that can form a smooth coating film on the color conversion filter layer 21 and does not deteriorate the function of the color conversion layer. More preferably, the material is a polymer material having high transparency in the visible region (transmittance of 50% or more in the range of 400 to 800 nm), electrical insulation, and barrier properties against moisture, oxygen, and low molecular components. It is.

When the black matrix, the color conversion filter layer 21, the smooth layer, and the like as described above are formed, the organic EL layer 25 and the like may be deteriorated by moisture, gas components, and the like generated therefrom. Therefore, although it is optional, it is desirable to form a gas barrier layer made of SiO ₂ , SiN or the like having a thickness of 50 nm to 1000 nm on these uppermost portions by sputtering or CVD.

A transparent electrode 22 (anode) is laminated by sputtering on the transparent substrate 11 or, if present, on the color conversion filter layer 21 described above. The transparent electrode 22 is formed using a conductive metal oxide such as SnO ₂ , In ₂ O ₃ , ITO, IZO, ZnO: Al. The transparent electrode 22 preferably has a transmittance of 50% or more, more preferably 85% or more with respect to light having a wavelength of 400 to 800 nm.

  The transparent electrode 22 is formed of a plurality of striped partial electrodes extending in the first direction. Such a transparent electrode 22 may be formed by using a mask that gives a desired shape, may be formed by first forming a uniform layer on the substrate and using photolithography, or the like, or You may form using a lift-off method.

Next, the shadow mask 23 is formed on the entire surface of the transparent substrate 11 and the transparent electrode 22 excluding openings at positions corresponding to a plurality of light emitting portions of the organic EL element. The shadow mask 23 can be formed using an organic or inorganic insulating material. For example, a photosensitive resist material such as a novolac resin film (for example, “JEM-700R2”, trade name, manufactured by JSR) can be used as the organic material, and SiO _x , SiN _x can be used as the inorganic material. Inorganic oxides or inorganic nitrides such as SiN _x O _y , AlO _x , TiO _x , and TaO _x can be used. Here, when an inorganic material is used for the shadow mask 23, the shadow mask 23 serves as a gas barrier layer that prevents moisture and oxygen from the color conversion filter layer 21 and the like provided thereunder from entering the organic EL layer 25. It can also have the function of. On the other hand, when an organic material such as a photosensitive resist material is used, processing of the shadow mask 23 can be realized with high accuracy only by a normal photo process, and the process can be simplified.

  The shadow mask 23 can have any color, but may be transparent (in this case, it is desirable to have a visible light transmittance of 70 to 100%). Alternatively, the shadow mask 23 can be made black to exhibit the same performance as the black matrix. The shadow mask 23 desirably has a thickness of 0.1 to 5 μm, preferably 1 to 2 μm, in order to ensure insulation.

  Next, the cathode separation wall 24 is continuously extended between the openings of the shadow mask 23 and in a direction orthogonal to the transparent electrode 22 (that is, a direction orthogonal to the first direction) using an organic resist material. As described above, the exposure amount and the exposure time were adjusted to form a desired cross-sectional shape by a photolithographic method. The cross-sectional shape of the cathode separation wall 24 may be any shape as long as the electrode can be accurately separated in the formation of the reflective electrode 26 and is not short-circuited with the anode. A reverse taper shape having an upper surface width of +3 to +10 μm and a height of 2 to 5 μm is preferable. With such a reverse taper shape, the inorganic protective layer 31 and the hygroscopic layer 33 described in detail below can be conveniently formed.

Next, the organic EL layer 25 is formed on the transparent electrode 22 and the cathode separation wall 24. The organic EL layer 25 includes at least an organic light emitting layer, and includes a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer as necessary. Each of these layers is formed to have a film thickness sufficient to realize desired characteristics in each layer. For example, what consists of the following layer structures is employ | adopted.
(1) Organic light emitting layer (2) Hole injection layer / organic light emitting layer (3) Organic light emitting layer / electron injection layer (4) Hole injection layer / organic light emitting layer / electron injection layer (5) Hole transport layer / Organic light emitting layer / electron injection layer (6) Hole injection layer / hole transport layer / organic light emitting layer / electron injection layer (7) Hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection Layer (In the above configuration, the electrode functioning as the anode is connected to the left side, and the electrode functioning as the cathode is connected to the right side)

  A hole injection / transport layer having both functions of a hole injection layer and a hole transport layer may be used, or an electron injection / transport layer having both functions of an electron injection layer and an electron transport layer may be used.

Any known material can be used as the material of the organic light emitting layer. For example, in order to obtain light emission from blue to blue-green, for example, fluorescent brighteners such as benzothiazole, benzimidazole, and benzoxazole, metal chelated oxonium compounds, styrylbenzene compounds, aromatic dimethylidin compounds Such materials are preferably used. Or you may form the organic light emitting layer which emits the light of a various wavelength range by adding a dopant to a host compound. Examples of host compounds include distyrylarylene compounds (for example, IDE-120 manufactured by Idemitsu Kosan Co., Ltd.), N, N′-ditolyl-N, N′-diphenylbiphenylamine (TPD), aluminum tris (8-quinolinolate) (Alq). ₃ ) etc. can be used. As dopants, perylene (blue purple), coumarin 6 (blue), quinacridone compounds (blue green to green), rubrene (yellow), 4-dicyanomethylene-2- (p-dimethylaminostyryl) -6-methyl- 4H-pyran (DCM, red), platinum octaethylporphyrin complex (PtOEP, red), or the like can be used.

  As a material for the hole injection layer, Pc (including CuPc) or indanthrene compounds can be used.

  The hole transport layer is composed of triphenylamine derivative (TPD), N, N′-bis (1-naphthyl) -N, N′-diphenylbiphenylamine (α-NPD), 4,4 ′, 4 ″ -tris- Triarylamine materials such as (N-3-tolyl-N-phenylamino) triphenylamine (m-MTDATA), N, N, N′-tetrabiphenyl-4,4′-biphenylenediamine (TBPB), etc. Can be used.

  As the electron transport layer, oxadiazole derivatives such as 2- (4-biphenyl) -5- (pt-butylphenyl) -1,3,4-oxadiazole (PBD), triazole derivatives, triazine derivatives, Phenylquinoxalines, aluminum quinolinol complexes (eg, Alq), and the like can be used.

As the material for the electron injection layer, an aluminum complex or an aluminum quinolinol complex doped with an alkali metal or an alkaline earth metal (for example, Alq ₃ ) may be used.

  In order to further improve the electron injection property, a buffer layer may be provided at the interface between the organic EL layer 25 and the reflective electrode 26. As the material of the buffer layer, alkali metals such as Li, Na, K, or Cs, alkaline earth metals such as Ba and Sr, alloys containing them, rare earth metals, or fluorides of these metals can be used. However, it is not limited to them. The film thickness of the buffer layer can be appropriately selected in consideration of the driving voltage, transparency, and the like, but in a normal case, it is preferably 10 nm or less.

  Each layer constituting the organic EL layer 25 can be formed by using any means known in the art such as vapor deposition (resistance heating or electron beam heating).

  The reflective electrode 26 (cathode) is laminated on the organic EL layer 25 by using any means known in the art such as vapor deposition (resistance heating or electron beam heating), ion plating, laser ablation. . The reflective electrode 26 is preferably formed using a metal such as Al or Ag having a reflectance of 90% or more, or an alloy thereof. Of these, low cost and high reflectivity Al is particularly preferable.

  In the present embodiment, a reverse-tapered cathode separation wall 24 as shown in FIG. 3 is formed in a direction orthogonal to the transparent electrode 22. Therefore, when the reflective electrode 26 made of Al or the like is formed by vapor deposition or the like, the components of the reflective electrode 26 are linearly deposited in the vertical direction without going around the base of the cathode separation wall. As a result, the reflective electrode 26 is divided, and a striped reflective electrode 26 extending in a direction orthogonal to the transparent electrode is formed.

The inorganic protective layer 31 is a layer that prevents moisture, oxygen, or the like that deteriorates the organic EL element from entering the element, and is made of a material such as SiO ₂ or SiN, and is applied by sputtering or CVD. The When the shadow mask 23 is made of an inorganic material, the shadow mask 23 itself has a function (gas barrier layer) equivalent to that of the inorganic protective layer 31. Therefore, the inorganic protective layer 31 is at least exposed as shown in FIG. It may be formed on the side surface portion of the EL layer 25 and the side surface portion and the upper surface portion of the reflective electrode 26, but preferably it is formed so as to cover the entire surface of the organic EL element as shown in FIG. Further, when the shadow mask 23 is an organic material, moisture and oxygen may enter the organic EL layer 25 through the shadow mask 23, so that the entire surface of the organic EL element is covered as shown in FIG. It is preferable to form so as to. As a method for forming the inorganic protective layer 31, it is desirable to use the above-described sputtering or CVD, in which the inorganic protective layer 31 component wraps around the shadowed portion of the cathode separation wall 24, but the substrate is revolved. If such means is taken, electron beam evaporation or ion plating can be used. The thickness of the inorganic protective layer 31 is selected in consideration of the protection performance and the film stress, but 50 nm to 1000 nm, preferably 100 nm to 600 nm is desirable.

  A hygroscopic layer 32 is provided on the inorganic protective layer 31. The hygroscopic layer 32 is not necessarily required if a layer having no defects can be formed as the inorganic protective layer 31 so as not to allow any moisture to permeate. However, such a perfect inorganic protective layer 31 is formed. Is very difficult to easily cause pinholes, grain boundary gaps, and other defects. Therefore, even if such a defect occurs in the inorganic protective layer 21, a moisture absorbing layer 32 is provided on the inorganic protective layer 31 so that moisture does not permeate therethrough.

The moisture absorption layer 32 is a layer that captures moisture that has penetrated through the bonding portion and moisture contained in the adhesive, and includes alkali metal oxides such as Na ₂ O and K ₂ O, CaO, SrO, BaO, It consists of materials such as alkaline earth metal oxides such as MgO, sulfates such as Na ₂ SO ₄ , CaSO ₄ and MgSO ₄ , metal halides such as CaCl ₂ and MgCl ₂ . The hygroscopic layer 32 is applied using a method similar to the method used in the inorganic protective layer 31, and as shown in FIG. 3 or FIG. 4, the organic EL layer exposed at least before the formation of the inorganic protective layer 31 The moisture absorbing layer 33 may be formed on the side surface portion 25 and the side surface portion and the upper surface portion of the reflective electrode 26. Preferably, the moisture absorbing layer 33 is formed so as to cover the entire surface of the organic EL element as shown in FIG. Good.

  Furthermore, the organic EL element of this embodiment can be moved into a dry nitrogen atmosphere (for example, oxygen 5 ppm or less, moisture 5 ppm or less) and sealed by a vacuum drop bonding method as shown in FIG. This vacuum dropping bonding method is a method in which an ultraviolet curable epoxy-based or acrylic low-viscosity adhesive 33 (having a viscosity of 0.3 to 3 Pa · s) is dropped on the sealing substrate 34, and then, 0. In this method, the sealing substrate 34 and the organic EL element are overlapped under a vacuum of 1 to 10 Pa, and subsequently released to atmospheric pressure to bond the organic EL element and the sealing substrate 34 together. According to this method, it is possible to fill the space between the organic EL element and the sealing substrate 34 with no adhesive. At this time, an ultraviolet curable epoxy-based or acrylic high-viscosity adhesive 61 (having a viscosity of 100 to 400 Pa · s is provided as a spacer at a position corresponding to the peripheral portion of the bonding portion on the sealing substrate 34. By preparing the bank portion in advance (which may contain beads), a clean filling shape and a constant gap interval can be maintained. After the bonding is completed, masking is performed as necessary, and ultraviolet rays are irradiated from the sealing substrate 34 side or the transparent substrate 11 side to cure the low viscosity adhesive 33 and the high viscosity adhesive 61, and the final organic An EL panel can be formed. In addition, when it substitutes with a thermosetting type adhesive agent, it can respond similarly by heating instead of an ultraviolet-ray.

  In addition, a filler having high thermal conductivity (for example, silicone, carbon fiber, metal powder, etc.) can be added to the adhesive described above. However, in this case, the condition that the ultraviolet curing is not hindered is necessary.

  It is preferable that the sealing substrate 34 can withstand the above-described sealing process conditions (adhesive component, temperature, etc.) and has excellent dimensional stability. Furthermore, it is preferable to select in consideration of the linear expansion coefficient with the transparent substrate 11 to be used. As a material of the sealing substrate 34, glass, metal, or a resin such as polyethylene terephthalate or polymethyl methacrylate can be used, and glass is particularly preferable. Alternatively, a flexible film formed from polyolefin, acrylic resin, polyester resin, polyimide resin, or the like can be used as the substrate.

  Further, if a shallow concave portion having a depth (several tens of μm) as thick as a laminated film of organic EL elements (including the organic EL layer 25 and the cathode separation wall 24) is provided on the sealing substrate 34, A narrow gap as shown in FIG. 1B can be formed at the periphery of the organic EL element, and the sealing performance can be improved more than the structure of FIG. 6B. In the case where the recess is formed by sandblasting, the cost of sandblasting generally depends largely on the processing depth, but the processing cost can be kept extremely low in the above relatively shallow recess processing.

  Hereinafter, the present invention will be described more specifically by way of examples. However, these examples do not limit the present invention, and it goes without saying that various modifications can be made without departing from the scope of the present invention. In addition, a present Example is based on the organic electroluminescent panel of the structure of FIG.

As the transparent substrate 11 of the organic EL element, an alkali-free glass substrate having a size of 230 mm × 200 mm × thickness 0.7 mm was used. When the substrate is used, a plurality of organic EL elements can be obtained. Hereinafter, one organic EL element among the plurality of organic EL elements will be described. A photosensitive photoresist was spin coated on the transparent substrate 11 other than the portion where the color conversion filter layer 21 was formed, and a black matrix was formed using a photolithography method. Next, a color filter and a color conversion layer constituting the color conversion filter layer 21 were sequentially formed by spin coating and subsequent photolithography. A smooth layer is formed on the upper surface of the formed black matrix and the color conversion filter layer 21 by spin coating and subsequent photolithography, and then about 200 nm of SiO ₂ is used to block moisture and gas components generated from each of these layers. A gas barrier layer was formed by sputtering. Here, an RF-planar magnetron apparatus was used as the sputtering apparatus, and Ar was used as the sputtering gas. The substrate temperature during the formation of the gas barrier layer was 80 ° C.

  Further, an IZO film having a thickness of 300 nm was formed on the entire surface of the gas barrier layer by sputtering using IDIXO (produced by Idemitsu Kosan Co., Ltd., a mixture of indium and zinc oxides and indium oxide) as a target. After spin-coating a resist agent “OFPR-800” (manufactured by Tokyo Ohka Co., Ltd.) on the formed IZO, patterning was performed by photolithography to form a transparent electrode 22 composed of a plurality of stripe-shaped partial electrodes. .

  An organic resist agent was applied thereon to form a 1 μm resist film, and then a shadow mask 23 was formed by providing an opening at a light emitting portion on the transparent electrode 22 by a photo process. The opening of the shadow mask 23 was about 80 μm × 240 μm. Next, the cathode separation wall 24 is formed in a portion located in the gap between the openings of the shadow mask 23 in a direction orthogonal to the extending direction of the stripe forming the transparent electrode 22 so as to be an organic EL element having a matrix driving structure. Formed. Here, the cathode separation wall 24 was made of an organic resist material, and the exposure time was adjusted to have a reverse taper shape with a top surface of about 12 μm width, a bottom surface of about 6 μm width, and a height of about 4 μm.

Next, the substrate formed up to the cathode separation wall 24 is mounted in a resistance heating vapor deposition apparatus, and a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron injection layer are sequentially formed without breaking the vacuum, An organic EL layer 25 was formed. During film formation, the internal pressure of the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. As the hole injection layer, copper phthalocyanine (CuPc) having a film thickness of 100 nm was laminated. As the hole transporting layer, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α-NPD) having a thickness of 20 nm was laminated. As the light emitting layer, 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi) having a thickness of 30 nm was laminated. As the electron injection layer, an aluminum chelate (Alq ₃ ) having a thickness of 20 nm was laminated.

  After the organic EL layer 25 is formed, the cathode separation wall 24 is used to form a stripe-shaped reflective electrode 26 extending in a direction orthogonal to the stripe of the transparent electrode 22 and made of Al having a thickness of 200 nm. The reflective electrode 26 was formed by vapor deposition without breaking the vacuum.

After forming the reflective electrode 26, the substrate is moved in-line (without opening to the atmosphere) into the facing sputtering chamber, the pressure is set to 1 Pa, the substrate temperature is set to 80 ° C., and Ar is used as the sputtering gas. An inorganic protective layer 31 made of SiO _{2 was formed} to a thickness of 200 nm. This counter sputtering hardly damages the organic EL layer 25 and can be expected to cause the sputter components to wrap around to the base of the cathode separation wall 24. Therefore, it is an effective means for forming the inorganic protective layer 31 and the moisture absorbing layer 33. It is. As shown in FIG. 5, the inorganic protective layer 31 formed as described above was formed on the entire surface without a gap until reaching the base of the cathode separation wall 24. Similarly, by using facing sputtering, a moisture absorbing layer 32 made of SrO is formed to a thickness of 2 μm so as to cover the entire surface of the inorganic protective layer 31 as shown in FIG. Formed.

  Next, the formed organic EL element was moved to a bonding apparatus having 5 ppm oxygen and 5 ppm water. In the laminating apparatus, 230 mm × 200 mm × 0.3 mm thick non-alkali flat glass (sealing substrate 34), which has been previously washed with acetone and vacuum heated and dried at 200 ° C. for 5 minutes, is set. Yes. As shown in FIG. 7, an ultraviolet curable bead-containing epoxy-based high-viscosity adhesive 61 is applied to a peripheral position of 56 mm × 46 mm corresponding to the peripheral portion of the bonding portion of the sealing substrate 34 with a dispenser. Subsequently, an ultraviolet curable epoxy low-viscosity adhesive 33 having a viscosity lower than that of the high-viscosity adhesive 61 is dropped at a position corresponding to the center portion of the panel, and the pressure is reduced to about 1 Pa to reduce the organic EL element and the sealing. A substrate 34 was attached. After bonding, the pressure was released to atmospheric pressure, and ultraviolet rays were irradiated from the sealing substrate 34 side. Then, it put in the heating furnace, heated at 80 degreeC for 1 hour, naturally cooled in the furnace for 30 minutes, and took out, and the organic EL panel was produced.

  As described above, according to the present invention, about 1 mm (transparent substrate 11 (thickness 0.7 mm) + sealing substrate 34 (thickness 0.3 mm) + organic EL element laminated film (total thickness about 50 μm) It has become clear that the thin organic EL panel of)) can be realized. In addition, since flat glass can be used for the sealing substrate 34, the cost is significantly higher than that of a conventional organic EL panel (hereinafter referred to as a conventional organic EL panel) using a glass having a recess. It was possible to reduce it. Furthermore, since the organic EL panel of the present invention is filled and bonded with an adhesive 34 between the organic EL element and the sealing substrate 34 without any gap, it is thinner than a conventional organic EL panel having a gap. The mechanical strength could be improved. The sealing performance of moisture, oxygen and the like was similar to that of the conventional organic EL panel, but the heat dissipation performance was improved by the adhesive 34 filled in the organic EL element and the sealing substrate 34 without any gaps. Compared to the EL panel, it can be expected to extend the operating life at the time of high luminance driving.

(A) is the schematic which shows the sealing area | region of a conventional organic EL panel, (b) is a schematic cross-sectional view of a conventional organic EL panel, (c) is the sealing of a conventional organic EL panel. It is the schematic which shows a stop area | region and a display part. It is a rough cross-sectional view which shows the sealing structure and film-forming state of a conventional organic EL panel. It is one Embodiment of the organic EL panel of this invention, and is a rough cross-sectional view which shows the sealing structure and film-forming state of this organic EL panel. It is one Embodiment of the organic electroluminescent panel of this invention, and is a rough cross-sectional view which shows the sealing structure and film-forming state of this organic electroluminescent panel. It is ideal embodiment of the organic electroluminescent panel of this invention, and is a schematic cross-sectional view which shows the sealing structure and film-forming state of this organic electroluminescent panel. (A) is the schematic which shows the sealing area | region of the organic electroluminescent panel of this invention, (b) is a schematic cross-sectional view of the organic electroluminescent panel of this invention, (c) is organic electroluminescent of this invention. It is the schematic which shows the sealing area | region and display part of a panel. It is the schematic which shows the sealing process of this invention by a vacuum drop bonding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Transparent substrate 12 Organic EL element laminated film 13 Adhesive 14 Glass substrate for sealing 15 Hygroscopic agent 16 Display part 17 Terminal extraction part 18 Adhesive sealing area | region 19 Recessed part 21 Color conversion filter layer 22 Transparent electrode 23 Shadow mask 24 Cathode separation Wall 25 Organic EL layer 26 Reflective electrode 27 End 31 Inorganic protective layer 32 Hygroscopic layer 33 Low viscosity adhesive 34 Substrate for sealing 61 High viscosity adhesive

Claims (7)

A transparent substrate, a transparent electrode formed in a stripe shape on the transparent substrate, a shadow mask formed to have a plurality of openings on the transparent electrode, a direction orthogonal to the transparent electrode, and the A cathode separation wall formed between the openings of the shadow mask, an organic EL layer including at least an organic light emitting layer formed in the opening of the shadow mask and on the cathode separation wall, and formed on the organic EL layer An organic EL element having a reflective electrode,
An organic EL element, further comprising: an inorganic protective layer formed so as to cover at least a side surface of the organic EL layer and a side surface and an upper surface of the reflective electrode; and a moisture absorbing layer formed on at least the inorganic protective layer . A transparent substrate, a transparent electrode formed in a stripe shape on the transparent substrate, a shadow mask formed to have a plurality of openings on the transparent electrode, a direction orthogonal to the transparent electrode, and the A cathode separation wall formed between the openings of the shadow mask, an organic EL layer including at least an organic light emitting layer formed in the opening of the shadow mask and on the cathode separation wall, and formed on the organic EL layer An organic EL element having a reflective electrode,
An organic EL element, further comprising an inorganic protective layer formed so as to cover the entire surface of the organic EL element, and a moisture absorbing layer formed on the inorganic protective layer.   3. The organic EL according to claim 2, wherein the moisture absorption layer is formed so as to cover at least a side surface portion of the organic EL layer located under the inorganic protective layer and a side surface portion and an upper surface portion of the reflective electrode. element.   The organic EL element according to claim 2, wherein the moisture absorption layer is formed so as to cover the entire surface of the inorganic protective layer.   The organic EL element according to claim 1, wherein a color conversion filter layer is formed between the transparent substrate and the transparent electrode. An organic EL panel having the organic EL element according to any one of claims 1 to 5, a sealing substrate, and an adhesive for joining the organic EL element and the sealing substrate,
An organic EL panel, wherein the organic EL element and the sealing substrate are bonded together by filling the adhesive without any gap between the organic EL element and the sealing substrate. The organic EL panel according to claim 6, wherein the sealing substrate is glass provided with a recess.

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