JP2011048937A - Organic el light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL light-emitting element with light extraction efficiency improved as well as visibility improved. <P>SOLUTION: The organic EL light-emitting element 1 consists of a first electrode 3, an organic layer 4 and a second electrode 5 laminated on a substrate 2 in this order. A fine concavo-convex structure 6, in which an arrangement period is equal to or lower than incident wavelength, is arranged between the substrate 2 and the first electrode 3 and toward the substrate 2 side; and a transparent layer 7 is arranged on the first electrode 3 side. A refractive index (n1) of a substance structuring the substrate 2 is to be a refractive index (n2) or more of a substance structuring the fine concavo-convex structure (n1≥n2). In the light-emitting element 1, since the fine concavo-convex structure 6 and the transparent layer 7 are inserted between the substrate 2 and the first electrode 3, and also the light-emitting element 1 satisfies the relation of n1≥n2, a refractive index difference between the substrate 2 and the first electrode 3 is inclined so as to reduce interface reflection generated by the refractive index difference. With this, light extraction efficiency can be enhanced. Additionally, since interface reflection of external light is reduced, visibility can be enhanced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence light-emitting element (hereinafter referred to as an organic EL light-emitting element) used for lighting fixtures, liquid crystal backlights, various displays, display devices, and the like.

  An example of an organic EL light emitting element (hereinafter referred to as a light emitting element) which is a conventional surface light emitter is shown in FIG. The light emitting element 101 includes a first electrode 3 sequentially stacked on a substrate 2, an organic layer 4 including an organic light emitting layer (not shown) made of an organic EL material, and a light reflective second electrode 5.

  In the light emitting element 101, the first electrode 3 injects holes into the organic layer 4 and the second electrode 5 injects electrons into the organic layer 4 by voltage application, and the injected holes and electrons are combined in the organic layer 4. The excitons generated by the transition to the ground state emit light. Light emitted from the organic layer 4 is emitted to the outside of the light emitting element 1 through the first electrode 3 and the substrate 2. However, in this light emitting element 101, part of the light emitted by the organic layer 4 is totally reflected by the refractive index step at the interface between the first electrode 3 and the substrate 2 or at the interface between the substrate 2 and the outside, so that the light extraction efficiency decreases. To do.

  Therefore, in order to improve the light extraction efficiency, it comprises a substrate, an organic EL element in which an anode, an organic light emitting layer, and a cathode are sequentially laminated, and a lens sheet or scattering particles provided between the substrate and the organic EL element. An organic EL device including a light scattering unit is known (see, for example, Patent Document 1). In this organic EL device, light having an angle larger than the critical angle at the interface between the light scattering portion and the substrate or at the interface between the substrate and the outside is forward scattered by the light scattering portion and becomes light within the critical angle. There is no total reflection at the interface. However, the amount of light extracted from this organic EL device is such that light that is originally within the critical angle of each interface before being scattered by the light scattering portion becomes light having an angle larger than the critical angle by the light scattering portion. Since it is totally reflected, it does not increase dramatically.

  Also, an organic EL element having a transparent resin layer, a transparent electrode, an organic EL layer, and a metal electrode in this order on a transparent substrate, and the transparent resin layer having a plurality of inverted dome-shaped recesses is known. (For example, refer to Patent Document 2). In this organic EL element, light having an angle larger than the critical angle at the interface between the transparent resin layer and the glass substrate and the interface between the glass substrate and the outside is within the critical angle because the inverted dome shape of the transparent resin layer functions as a convex lens. Since it becomes light, it is not totally reflected at each interface. However, this organic EL element has a refractive index step at the interface between the transparent resin layer and the glass substrate, and the reflection caused only by the refractive index step independent of the incident angle cannot be reduced, so that the amount of extracted light does not increase significantly.

  Further, a cathode layer, a light emitting layer, and an anode layer are sequentially laminated on the substrate, and the light emitting layer and the cathode layer are in contact with each other with a moth-eye structure, and light generated in the light emitting layer is transmitted from the opposite side to the substrate side. A top emission type optical device that emits light is known (see, for example, Patent Document 3). The moth-eye structure is a nanometer-order fine concavo-convex structure that mimics the eye of the eye, and is used to form a stable non-reflective surface on an optical element. In this light utilization device, since the moth-eye structure suppresses reflection of external light, the contrast of light irradiated from the light emitting layer is suppressed from being lowered. However, in this optical device, since the moth-eye structure is formed on the surface of the light emitting layer opposite to the light extraction side and does not contribute to the improvement of the light extraction efficiency, the amount of light extraction does not increase.

JP-A-8-83688 JP 2004-47383 A JP 2004-258364 A

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an organic EL light-emitting element that can improve light extraction efficiency and visibility.

  In order to achieve the above object, the invention of claim 1 is formed by laminating a first electrode composed of a transparent conductive film on a substrate, an organic layer including at least one organic light emitting layer, and a second electrode in this order, In a bottom emission type organic EL light emitting device that emits light generated in an organic layer from the substrate side, a fine concavo-convex structure between the substrate and the first electrode and having an arrangement period equal to or less than an incident wavelength on the substrate side , N1 ≧ n2 where a transparent layer is provided on the first electrode side, and the refractive indexes of the substrate and the material constituting the fine concavo-convex structure are n1 and n2, respectively.

  According to a second aspect of the present invention, in the organic EL light-emitting device according to the first aspect, a scattering layer is provided on the light emission surface of the substrate.

  According to a third aspect of the present invention, a first electrode made of a transparent conductive film, an organic layer including at least one organic light emitting layer, and a second electrode are stacked in this order on a substrate, and light generated in the organic layer is generated. In the bottom emission type organic EL light emitting device that emits from the substrate side, a fine concavo-convex structure having an arrangement period equal to or less than an incident wavelength is provided on the light emitting surface of the substrate.

  According to a fourth aspect of the present invention, a first electrode, an organic layer including at least one organic light emitting layer, and a second electrode made of a transparent conductive film are stacked in this order on a substrate, and light generated in the organic layer is generated. In the top emission type organic EL light emitting device that emits light from the side opposite to the substrate side, a fine concavo-convex structure having an arrangement period equal to or less than an incident wavelength is provided on the light emitting surface of the second electrode.

  According to a fifth aspect of the present invention, in the organic EL light-emitting device according to the fourth aspect of the present invention, n3 ≧ n4, where n3 and n4 are refractive indexes of the materials constituting the fine concavo-convex structure and the second electrode, respectively. It is.

  The invention according to claim 6 is the organic EL light-emitting device according to any one of claims 1 to 5, wherein the base surface on which the fine concavo-convex structure is formed has a single or plural bases with respect to the organic layer side. It includes a concave or convex shape or a cross-sectional shape made of a composite thereof.

  According to a seventh aspect of the present invention, in the organic EL light-emitting device according to the sixth aspect, the concave or convex shape is a stripe shape, a lattice shape, a concentric circle shape or a honeycomb shape when the base surface forming the fine concavo-convex structure is viewed in plan view. Are arranged.

  According to the invention of claim 1, the fine concavo-convex structure and the transparent layer are inserted between the substrate and the first electrode, and the refractive index (n1) of the material constituting the substrate constitutes the fine concavo-convex structure. Since the refractive index (n2) of the substance is equal to or higher than the refractive index step between the substrate and the first electrode, the interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be improved. In addition, since the interface reflection of external light is reduced, visibility can be improved.

  According to the invention of claim 2, since the scattering layer is disposed on the light emitting surface of the substrate, the refractive index step between the substrate and the outside is inclined, and the interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be further improved. Moreover, since interface reflection of external light is reduced, visibility can be further improved.

  According to the invention of claim 3, since the fine concavo-convex structure is provided on the substrate, the refractive index step between the substrate and the outside is inclined, and the interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be improved. In addition, since the interface reflection of external light is reduced, visibility can be improved.

  According to the invention of claim 4, since the fine concavo-convex structure is disposed on the second electrode, the refractive index step between the second electrode and the outside is inclined, and the interface reflection caused by the refractive index step is reduced. . Thereby, the light extraction efficiency can be improved. In addition, since the interface reflection of external light is reduced, visibility can be improved.

  According to the invention of claim 5, since the refractive index (n3) of the substance constituting the fine concavo-convex structure is equal to or higher than the refractive index (n4) of the substance constituting the second electrode, The refractive index step between the two electrodes is more inclined, and the interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be further improved. Moreover, since interface reflection of external light is reduced, visibility can be further improved.

  According to the invention of claim 6, since the base surface forming the fine concavo-convex structure includes a cross-sectional shape made of a concave or convex shape, the refractive index between the fine concavo-convex structure and the layer contacting the fine concavo-convex structure and the base surface Since the step is further inclined and the interface reflection caused by the refractive index step is reduced, the light extraction efficiency can be further improved. Moreover, since interface reflection of external light is reduced, visibility can be further improved.

  According to the invention of claim 7, since the concave or convex shape of the base surface forming the fine concavo-convex structure is a repetitive shape, it is possible to achieve uniform light emission.

1 is a side sectional view of an organic EL light emitting device according to a first embodiment of the present invention. The sectional side view which shows the modification of the organic EL light emitting element. The sectional side view which shows the other modification of the organic EL light emitting element. (A)-(d) is a top view which shows the various patterns which concern on the concave or convex arrangement | positioning of the base surface which forms the fine concavo-convex structure of the organic EL light emitting element. The side sectional view of the organic EL light emitting element concerning a 2nd embodiment of the present invention. The side sectional view of the organic EL light emitting element concerning a 3rd embodiment of the present invention. Sectional drawing of the conventional organic electroluminescent light emitting element.

(First embodiment)
FIG. 1 shows a configuration of an organic EL light emitting device 1 (hereinafter referred to as a light emitting device) according to a first embodiment of the present invention. The light emitting element 1 is formed by laminating a first electrode 3 made of a transparent conductive film, an organic layer 4 including at least one organic light emitting layer (not shown), and a second electrode 5 on a substrate 2 in this order. In addition, the light emitting element 1 includes a fine concavo-convex structure 6 on the substrate 2 side and a transparent layer 7 on the first electrode 3 side between the substrate 2 and the first electrode 3. The light emitting element 1 is a bottom emission type that emits light generated in the organic layer 4 from the substrate 2 side.

  The refractive index of the substance constituting the substrate 2 is n1, and the refractive index of the substance constituting the fine uneven structure 6 is n2. The material of the substrate 2 is such that the refractive index (n1) of the substance constituting the substrate 2 is equal to or higher than the refractive index (n2) of the substance constituting the fine concavo-convex structure 6 (n1 ≧ n2). Any transparent material such as soda glass or non-alkali glass, or a flexible transparent plastic plate such as polycarbonate or polyethylene terephthalate may be used.

  The first electrode 3 is, for example, an ultrathin metal such as indium-tin oxide (ITO), indium-zinc oxide (IZO), tin oxide, Au, a conductive polymer, a conductive organic material, or a dopant. As the material, a (donor or acceptor) -containing organic layer, a mixture of a conductor and a conductive organic material (including a polymer), or a laminate thereof is used. The first electrode 3 is formed by depositing these materials using a vapor phase growth method such as a sputtering method or an ion plating method. Although the film thickness of the 1st electrode 3 is not specifically limited, 50-300 nm is preferable.

  The organic light emitting layer of the organic layer 4 is, for example, anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, Quinoline metal complex, tris (8-hydroxyquinolinate) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8-quinolinato) aluminum complex, aminoquinoline metal complex, benzoquinoline metal Complexes, tri- (p-terphenyl-4-yl) amine, pyran, quinacridone, rubrene, and derivatives thereof, or 1-aryl-2,5-di (2-thienyl) pyrrole derivatives, disty Rubenzen derivatives, styryl arylene derivatives, styrylamine derivatives, and the like compound or polymer having a group consisting of luminescent compounds in a part of the molecule is used as a material. In addition to compounds derived from fluorescent dyes typified by the above compounds, so-called phosphorescent materials, for example, luminescent materials such as Ir complexes, Os complexes, Pt complexes, and europium complexes, or compounds having these in the molecule or high Molecules are also used. The organic layer 4 may include a hole injection layer, a hole import layer, an electron transport layer, and an electron injection layer in addition to the organic light emitting layer.

The second electrode 5 is made of a single material such as Al or silver, or a material composed of a combination of Al and silver and another electrode material to form a laminated structure. Combinations of electrode materials include alkali metal and Al laminates, alkali metal and silver laminates, alkali metal halides and Al laminates, alkali metal oxides and Al laminates, alkaline earth metals and rare earths. A laminated body of metal and Al, alloys of these metal species and other metals, and the like can be given. Specifically, for example, sodium, sodium-potassium alloy, lithium, magnesium, etc. and Al laminate, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, mixture of LiF and Al, Al and Al ₂ O _{And the} like.

  In the fine concavo-convex structure 6, the arrangement period is equal to or less than the incident wavelength, and the cross-sectional shape of the concavo-convex structure pattern is a radial concave or convex shape. Note that the cross-sectional shape of the concavo-convex structure pattern may be a rectangular shape or a V-shaped concave or convex shape. The material of the fine concavo-convex structure 6 may be any material as long as the refractive index (n1) of the substance constituting the substrate 2 is equal to or higher than the refractive index (n2) of the substance constituting the fine concavo-convex structure 6, and acrylic resin, polyethylene, Polypropylene, polyethylene terephthalate, polymethyl methacrylate, polystyrene, polyethersulfone, polyarylate, polycarbonate resin, polyurethane, polyacrylonitrile, polyvinyl acetal, polyamide, polyimide, diacryl phthalate resin, cellulosic resin, polyvinyl chloride, polychlorinated Examples thereof include vinylidene, polyvinyl acetate, other thermoplastic resins, and two or more copolymers of monomers constituting these resins.

The fine concavo-convex structure 6 has a resist thin film formed on the substrate 2 by spin coating, screen printing, dip coating, die coating, casting, spray coating, gravure coating, or the like, and lithography using light or an electron beam on the resist thin film. It is formed by nanoimprinting. Specifically, when the fine concavo-convex structure 6 is formed by, for example, nanoimprinting, which is a simple method for forming a nano-order periodic structure, the concavo-convex structure of several tens to several hundreds nm processed by an electron beam or the like. The concavo-convex structure pattern is formed by pressing the stamper having a pressure against a soft resist thin film on the substrate 2 and then peeling it. A stamper used for nanoimprinting is formed on a base material such as Si or SiO ₂ so as to have at least one concavo-convex structure pattern by lithography, etching technique, electron beam direct drawing technique such as focused ion beam (FIB). The film pressure of the fine concavo-convex structure 6 is not particularly limited, but is preferably in the range of 0.01 to 20 μm.

  The transparent layer 7 is provided to fill and planarize the irregularities on the surface of the fine concavo-convex structure 6. In the light emitting element 1, the first electrode 3 having a thin film pressure is formed on the smooth surface of the transparent layer 7. For this reason, since the film pressure of the first electrode 3 does not become non-uniform, there is no possibility of causing a problem in electrical characteristics or causing a short circuit.

  The material of the transparent layer 7 may be any material that has optical transparency, and examples thereof include polyester, polyether, polyether ketone, polyimide, polyamide, polyimide amide, epoxy, polyurethane, polyurethane acrylate, and polycarbonate. It is done. In particular, it is preferable to use a thermosetting resin having a high refractive index such as polyimide, polyamideimide, epoxy, and polyurethane. The transparent layer 7 is formed by coating these materials on the surface of the fine concavo-convex structure 6 and then curing by heating. Although the film | membrane pressure of the transparent layer 7 is not specifically limited, The range of about 1-20 micrometers is preferable. Further, the flatness of the surface of the transparent layer 7 is measured using a contact pressure gauge Dektak 6 (trade name, manufactured by ULVAC, Inc.) under the conditions of a measurement distance of 5000 μm, a load of 0.5 mg, and a measurement time of 20 sec. The arithmetic average roughness Ra (JIS B0601) is preferably 200 nm or less, and more preferably 50 nm or less.

  The refractive index of the material forming the transparent layer 7 is higher than the refractive index of the first electrode 3. Thereby, in the light emitting element 1, since the optical interface between the transparent layer 7 and the first electrode 3 is eliminated, total reflection at this interface is reduced, and more light can be guided to the fine concavo-convex structure 6. it can. In addition, when the refractive index of the substance which forms the transparent layer 7 is lower than the refractive index of the 1st electrode 3, it is desirable that the difference in refractive index with the 1st electrode 3 is small.

  In the light emitting element 1, the fine concavo-convex structure 6 and the transparent layer 7 are inserted between the substrate 2 and the first electrode 3, and the refractive index (n1) of the substance constituting the substrate 2 constitutes the fine concavo-convex structure 6. Since the refractive index (n2) or higher of the substance being used is (n1 ≧ n2), the refractive index step between the substrate 2 and the first electrode 3 is inclined, and interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be improved. In addition, since the interface reflection of external light is reduced, visibility can be improved.

  FIG. 2 shows a light emitting device 1 according to a first modification of the present embodiment. The light emitting element 1 includes a scattering layer 8 on the light emission surface of the substrate 2, and other configurations are the same as those in the first embodiment. The scattering layer 8 is formed by applying a solution obtained by adding methyl silicone particles to a silicone resin solution, which is a binder forming material, onto the substrate 2 and baking it. In the light emitting element 1, the scattering layer 8 is disposed on the light emission surface of the substrate 2. Thereby, the refractive index step between the substrate 2 and the outside is inclined, and the interface reflection caused by the refractive index step is reduced, so that the light extraction efficiency can be further improved. Moreover, since interface reflection of external light is reduced, visibility can be further improved.

  FIG. 3 shows a light emitting device 1 according to a second modification of the present embodiment. In this light emitting element 1, the base surface 9 forming the fine concavo-convex structure 6 includes a cross-sectional shape made of a single or a plurality of concave or convex shapes or a composite thereof with respect to the organic layer 4 side. The configuration is the same as that of the first embodiment. The base surface 9 on which the fine concavo-convex structure 6 is formed is formed by processing the substrate 2 by lithography using light or an electron beam.

  FIGS. 4A to 4D show examples of concave or convex arrangement patterns in plan view of the base surface 9 that forms the fine concavo-convex structure 6. Concave portions or convex portions having a concave shape or a convex shape are arranged in a stripe shape, a lattice shape, a concentric circle shape, and a honeycomb shape, which are equally spaced. Even if any arrangement pattern is used, since it is a repeated shape, it is possible to achieve uniform light emission.

  In the light emitting element 1, since the base surface 9 forming the fine concavo-convex structure 6 includes a cross-sectional shape made of a concave or convex shape, the refractive index step between the fine concavo-convex structure 6 and the substrate 2 is more inclined and refracted. The interface reflection caused by the rate difference is reduced. Thereby, the light extraction efficiency can be further improved. Moreover, since interface reflection of external light is reduced, visibility can be further improved.

(Second Embodiment)
FIG. 5 shows a light emitting device 1 according to the second embodiment. The light emitting element 1 includes a fine concavo-convex structure 6 whose arrangement period is equal to or less than the incident wavelength on the light emission surface of the substrate 2, and other configurations are the same as those of the first embodiment. In the light emitting element 1, since the fine concavo-convex structure 6 is installed on the substrate 2, the refractive index step between the substrate 2 and the outside is inclined, and interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be improved. In addition, since the interface reflection of external light is reduced, visibility can be improved. In the light emitting element 1, the base surface 9 on which the fine concavo-convex structure 6 is formed may include a cross-sectional shape made of a concave or convex shape with respect to the organic layer 4 side.

(Third embodiment)
FIG. 6 shows a light emitting device 1 according to the third embodiment. The light emitting element 1 is a top emission type in which the second electrode 5 is made of a transparent conductive film and emits light generated in the organic layer 4 from the side opposite to the substrate 2 side. Further, a fine concavo-convex structure 6 having an arrangement period equal to or less than the incident wavelength is provided on the light emission surface of the second electrode 5. When the refractive indexes of the substances constituting the fine uneven structure 6 and the second electrode 5 are n3 and n4, respectively, the refractive index (n3) of the substance constituting the fine uneven structure is that of the substance constituting the second electrode. Refractive index (n4) or more is set (n3 ≧ n4). Other configurations are the same as those of the second embodiment.

  In the light emitting element 1, since the fine concavo-convex structure 6 is disposed on the second electrode 5, the refractive index step between the second electrode 5 and the outside is inclined, and interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be improved. In addition, since the interface reflection of external light is reduced, visibility can be improved.

  In the light emitting element 1, since the refractive index (n3) of the substance constituting the fine concavo-convex structure 6 is equal to or higher than the refractive index (n4) of the substance constituting the second electrode 5 (n3 ≧ n4), The refractive index step between the fine concavo-convex structure 6 and the second electrode 5 is further inclined, and interface reflection caused by the refractive index step is reduced. Thereby, the light extraction efficiency can be further improved. Moreover, since interface reflection of external light is reduced, visibility can be further improved.

  Next, Examples 1 to 4 and Comparative Examples 1 to 3 in the light-emitting element 1 according to the present invention will be described.

Example 1
As the substrate 2, an alkali-free glass plate (manufactured by Corning International Co., Ltd., product number: 1737, refractive index 1.50 to 1.53 at a wavelength of 500 nm) is used. A polymethylmethacrylate (PMMA) solution is applied on the substrate 2 so as to have a film pressure of 100 nm, and then heated to 120 ° C. to form a PMMA film as a resist thin film.

  A stamper having a convex portion having a triangular structure with a sectional shape of 100 nm in height is formed by electron beam exposure. When the stamper is viewed in plan, the protrusions are stripes arranged at a center-to-center pitch of 300 nm. The stamper was pressed against the PMMA film on the substrate 2 at 5 to 10 MPa, held for 1 minute, and then peeled to form a fine relief structure 6. The refractive index (n2) of the fine relief structure 6 is 1.49 at a wavelength of 500 nm, which is smaller than the refractive index (n1) of the substrate 2.

The fine concavo-convex structure 6 has approximately 3 irgacure 184 (registered trademark, manufactured by Ciba Japan Co., Ltd.) as a photopolymerization initiator on Ogsol EA-0200 (registered trademark, manufactured by Osaka Gas Chemical Co., Ltd.) which is an acrylate on the surface. A spin coater is applied to the solution with added%. The applied solution is cured by UV irradiation with an integrated light amount of 300 mJ / cm ² and formed in a 5 μm transparent layer 7. The refractive index of the transparent layer 7 is 1.62 at a wavelength of 500 nm. As for the transparent layer 7, the 1st electrode 3 which is an ITO film | membrane with a film | membrane pressure of 150 nm is formed on the surface using an ITO target (made by Tosoh Corporation). The substrate 2 on which the first electrode 3 is formed is subjected to UV-O ₃ treatment for 5 minutes.

  Next, the substrate 2 on which the first electrode 3 is formed is set in a vacuum deposition apparatus, and an organic layer 4 including a hole transport layer, an electron transport layer / organic light emitting layer, and an electron injection layer is formed. Specifically, N, N′-diphenyl-N, N′-bis (1-naphthyl) -1,1′-biphenyl-4,4′-diamine (NPB) (NPay) is applied on the first electrode 3. Are used to form a hole transport layer having a film pressure of 40 nm. On this hole transport layer, an electron transport layer / organic light emitting layer having a film pressure of 60 nm is formed using aluminum-tris (8-hydroxyquinoline) (Alq) (manufactured by eRay). An electron injection layer having a film pressure of 1 nm is formed on the electron transport layer / organic light emitting layer using LiF (manufactured by Kojundo Chemical Laboratory Co., Ltd.).

  On the organic layer 4, Al (manufactured by Kojundo Chemical Laboratory Co., Ltd.) is vacuum-deposited to form the second electrode 5 that is a cathode having a film pressure of 80 nm. In a glove box in a dry nitrogen atmosphere with a dew point of -80 ° C or lower, a sealing cap is attached to the substrate 2 with a sealing agent so as to surround each layer, and the sealing agent is cured by irradiating ultraviolet rays to seal each layer with a sealing cap. Thus, a bottom emission type light emitting element 1 (see FIG. 1) was obtained.

(Example 2)
A bottom emission type light emitting device 1 (see FIG. 5) was obtained in the same manner as in Example 1 except that the fine uneven structure 6 was provided on the light emitting surface of the substrate 2 and the transparent layer 7 was not provided.

(Example 3)
The top of the second electrode 5 is the same as in Example 2 except that the ITO target (manufactured by Tosoh Corporation) is used to form a 150 nm ITO film and the fine uneven structure 6 is provided on the light emission surface of the second electrode 5. An emission type light emitting device 1 (see FIG. 6) was obtained.

Example 4
A bottom emission type light emitting device 1 (see FIG. 4) was obtained in the same manner as in Example 1 except that the scattering layer 8 was provided on the light emission surface of the substrate 2. Specifically, 803.5 parts by mass of isopropyl alcohol is added to 86.8 parts by mass of tetraethoxysilane, 34.7 parts by mass of γ-methacryloxypropyltrimethoxysilane, and 75 parts by mass of 0.1N nitric acid are added. A solution was obtained by mixing well using a disper. This solution was stirred for 2 hours in a constant temperature bath at 40 ° C. to obtain a 5% by mass silicone resin solution as a binder forming material having a weight average molecular weight of 1050. To this silicone resin solution, Tospearl 120 (registered trademark, manufactured by Momentive Co., Ltd., particle diameter: 2 μm), which is methyl silicone particles, is 80/20 based on the solid content mass of methyl silicone particles / silicone resin (condensed compound equivalent). The resultant was added and dispersed with a homogenizer to obtain a methyl silicone particle-dispersed silicone resin solution. In addition, in the case of tetraalkoxysilane, the condensed compound conversion is a mass assuming that Si present is SiO ₂ , and in the case of trialkoxysilane, it is a mass assuming Si present is SiO _1.5 . A methylsilicone particle-dispersed silicone resin solution was applied to the substrate 2 with a spin coater at 1000 rpm, and baked at 200 ° C. for 10 minutes to obtain a light-emitting element 1 having a scattering layer 8 having a thickness of 5 μm.

(Comparative Example 1)
A bottom emission type light emitting device was obtained in the same manner as in Example 1 except that the fine uneven structure 6 and the transparent layer 7 were not provided.

(Comparative Example 2)
Except that the fine concavo-convex structure 6 is made of a polystyrene solution, the refractive index (n2) is 1.58 at a wavelength of 500 nm, and is larger than the refractive index (n1) of the substrate 2 (n1 <n2). Thus, a bottom emission type light emitting device was obtained.

(Comparative Example 3)
A top emission type light-emitting element was obtained in the same manner as in Comparative Example 1 except that the second electrode 5 was an ITO film having a thickness of 150 nm using an ITO target (manufactured by Tosoh Corporation).

  The current efficiency and power efficiency of the light-emitting elements 1 according to Examples 1 to 4 and the light-emitting elements according to Comparative Examples 1 to 3 were measured. Further, it was determined how many times the values of the current efficiency and the power efficiency of each light emitting element were compared with each value of the light emitting element of Comparative Example 1. The measurement results are shown in Table 1 below.

  As is apparent from the measurement results of the current efficiency and power efficiency of the light-emitting elements 1 of Examples 1 to 4 and the light-emitting elements of Comparative Examples 1 to 3, according to the light-emitting element 1 of this embodiment, the top emission The light extraction efficiency is improved in both the case and the bottom emission type.

  In addition, this invention is not restricted to the structure of said embodiment, A various deformation | transformation is possible in the range which does not change the summary of invention. For example, when a fine uneven structure is provided on the light emission surface of the substrate or the second electrode, a scattering layer may be further provided on the light emission surface of the fine uneven structure.

1 Light emitting element (organic EL light emitting element)
2 Substrate 3 First electrode 4 Organic layer 5 Second electrode 6 Fine uneven structure 7 Transparent layer 8 Scattering layer 9 Lower ground

Claims (7)

A bottom formed by laminating a first electrode made of a transparent conductive film on a substrate, an organic layer including at least one organic light emitting layer, and a second electrode in this order, and emitting light generated in the organic layer from the substrate side In an emission type organic EL light emitting device,
A fine concavo-convex structure having an arrangement period equal to or less than an incident wavelength between the substrate and the first electrode on the substrate side, and a transparent layer on the first electrode side,
An organic EL light-emitting element, wherein n1 ≧ n2 where n1 and n2 are refractive indexes of the substrate and the material constituting the fine concavo-convex structure, respectively.   The organic EL light-emitting element according to claim 1, further comprising a scattering layer on a light emission surface of the substrate. A bottom formed by laminating a first electrode made of a transparent conductive film on a substrate, an organic layer including at least one organic light emitting layer, and a second electrode in this order, and emitting light generated in the organic layer from the substrate side In an emission type organic EL light emitting device,
An organic EL light emitting device comprising a fine concavo-convex structure having an arrangement period equal to or less than an incident wavelength on a light emission surface of the substrate. A first electrode, an organic layer including at least one organic light emitting layer, and a second electrode made of a transparent conductive film are laminated in this order on the substrate, and light generated in the organic layer is transmitted from the side opposite to the substrate side. In a top emission type organic EL light emitting device that emits,
An organic EL light emitting device comprising a fine concavo-convex structure having an arrangement period equal to or less than an incident wavelength on a light emission surface of the second electrode.   5. The organic EL light emitting element according to claim 4, wherein n3 ≧ n4, where n3 and n4 are refractive indexes of the materials constituting the fine concavo-convex structure and the second electrode, respectively.   6. The base surface forming the fine concavo-convex structure includes a cross-sectional shape made of a single or a plurality of concave or convex shapes or a composite thereof with respect to the organic layer side. The organic electroluminescent light emitting element as described in any one.   7. The organic EL light emitting device according to claim 6, wherein when the base surface forming the fine concavo-convex structure is viewed in plan, the concave or convex shapes are arranged in a stripe shape, a lattice shape, a concentric circle shape, or a honeycomb shape. element.

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