WO2017141748A1

WO2017141748A1 - Organic el element, lighting device, surface light source and display device

Info

Publication number: WO2017141748A1
Application number: PCT/JP2017/004176
Authority: WO
Inventors: 玲子吉成
Original assignee: 凸版印刷株式会社
Priority date: 2016-02-18
Filing date: 2017-02-06
Publication date: 2017-08-24
Also published as: JP2017147146A

Abstract

Provided are: an organic EL element which has both high light extraction efficiency and high emission uniformity; a lighting device; a surface light source; and a display device. This organic EL element (10) is obtained by sequentially laminating, in the following order: a light-transmitting substrate (11); a structural layer (12) that has at least two micro-regions including a recessed and projected region, which is composed of a plurality of recessed and projected portions (23) formed on a surface that is on the reverse side of the substrate (11)-side surface, and a flat region which is composed of a flat portion; a light-transmitting first electrode layer (14); a functional layer (15) that contains a light emitting layer; and a second electrode layer (16). In this connection, the organic EL element (10) may comprise a barrier layer (13) that is provided between the structural layer (12) and the first electrode layer. The organic EL element (10) may further comprise a light extraction lens layer (30) that is provided on a surface of the substrate (11), said surface being on the reverse side of the surface on which the structural layer (12) is formed.

Description

Organic EL element, lighting device, planar light source, and display device

The present invention relates to an organic EL element, an illumination device, a planar light source, and a display device.

In recent years, a light-emitting element (organic EL element) utilizing an organic electroluminescence (EL) phenomenon, which is an electroluminescence phenomenon of an organic material, has attracted a great deal of attention as a next-generation light-emitting device used in lighting devices, display devices, and the like. ing. The organic EL element has advantages such as surface light emission, low-temperature operation, cost reduction, weight reduction, and flexible element fabrication.
An organic EL element generally includes an organic EL layer including a light emitting layer containing an organic light emitting material, and an anode and a cathode provided on both surfaces of the organic EL layer, respectively. As the organic EL layer, an electron transport layer, a hole transport layer, and the like are provided as necessary in addition to the light emitting layer. The organic EL element is composed of an anode made of a transparent conductive material such as ITO (Indium Tin Oxide), which is sequentially formed on a transparent substrate such as a glass substrate, an organic EL layer including a light emitting layer, and a metal. A cathode is provided. The organic EL element is a bottom emission type element in which light is extracted from the substrate side, or a top emission type element in which a cathode, an organic EL layer, and an anode are sequentially formed on the substrate, and light is extracted from the side opposite to the substrate side. There are elements.

In addition to the above-described advantages, the organic EL element has advantages such as low viewing angle dependency, low power consumption, and extremely thin devices, but also has a problem of low light extraction efficiency. The light extraction efficiency is the ratio of the light energy emitted from the light extraction surface (for example, the substrate surface in the case of the bottom emission type) to the atmosphere with respect to the light energy emitted from the light emitting layer. For example, light emitted from the light-emitting layer is emitted in all directions, so that most of the light enters a waveguide mode in which total reflection is repeated at the interface between multiple layers with different refractive indexes. As a result, the light extraction efficiency decreases.

Further, in the organic EL element, since the distance between the light emitting layer and the cathode that is a metal is short, a part of the near-field light from the light emitting layer is converted to surface plasmon on the surface of the cathode and lost, Light extraction efficiency decreases. Since the light extraction efficiency affects the brightness of a display provided with an organic EL element, illumination, and the like, various methods have been studied for the improvement.
As one method for improving the light extraction efficiency, there is an organic EL element using a glass substrate provided with a light condensing layer exhibiting light condensing properties. For example, Patent Document 1 discloses a light collecting layer including a light collecting structure such as a microlens and a transparent resin that covers the light collecting structure. In Patent Document 1, a material having a higher refractive index than the light condensing structure is used as the transparent resin. In Patent Document 1, by providing such a condensing layer on a glass substrate, total reflection occurring on the surface of the glass substrate is suppressed, and the light extraction efficiency is improved.

Also, as one method for improving the light extraction efficiency, a method using surface plasmon resonance has been proposed. For example, Patent Document 2 discloses a method of providing a one-dimensional or two-dimensional periodic fine structure on the surface of a metal layer (cathode). In these methods, the periodic microstructure functions as a diffraction grating. Thereby, the energy lost as surface plasmons on the cathode surface is extracted as light, and the light extraction efficiency is improved.

JP 2003-86353 A Japanese Patent No. 4762542

However, even if the light condensing layer as described above is provided on the glass substrate, total reflection occurs at the interface between the light condensing layer and the glass substrate, so that the light extraction efficiency from the organic EL element is not necessarily high enough. Absent. In addition, when a periodic fine structure as described above is provided in a metal layer, when actually manufacturing an organic EL element, a leak electrode is generated due to a concavo-convex structure, light emission unevenness due to unevenness of each layer to be laminated, and stability over time There was also a problem of lowering. For this reason, even if a periodic structure that is theoretically efficient is provided, it is not always possible to stably manufacture the organic EL element. On the other hand, organic EL elements with higher light extraction efficiency are required for power saving and flexibility of organic EL lighting.

An object of the present invention is to provide an organic EL element having both high light extraction efficiency and high light emission uniformity, as well as an illumination device, a planar light source, and a display device.

In order to achieve the above object, an organic EL element according to one embodiment of the present invention includes a light-transmitting substrate and a plurality of uneven portions that are light-transmitting and are formed on a surface opposite to the substrate. A structure layer having at least two types of regions of a concavo-convex region made of and a flat region made of a flat portion, a first electrode layer having light transmittance, a functional layer including a light emitting layer, and a second electrode layer, They are stacked in this order.
In addition, a lighting device, a planar light source, and a display device according to one embodiment of the present invention include at least part of the above-described organic EL element.

According to one embodiment of the present invention, an organic EL element having both high light extraction efficiency and high light emission uniformity, as well as a lighting device, a planar light source, and a display device can be realized.

It is sectional drawing which shows schematically the organic EL element which concerns on one Embodiment of this invention. It is a top view which shows roughly the light extraction board | substrate which concerns on one Embodiment of this invention. It is sectional drawing which shows roughly the illuminating device which concerns on one Embodiment of this invention. It is sectional drawing which shows schematically the display apparatus which concerns on one Embodiment of this invention.

<Embodiment>
Embodiments of the present invention will be described below with reference to the drawings.
It should be noted that the present invention is not limited to the embodiments described below, and it is possible to make changes in design and the like based on the knowledge of those skilled in the art, and embodiments in which such changes are added are also possible. It is included in the scope of the present invention.
As shown in FIG. 1, the organic EL element 10 according to this embodiment includes a structural layer 12, a barrier layer 13, a first electrode layer 14, a functional layer 15, and a second layer on one surface side of a light transmissive substrate 11. The electrode layer 16 is laminated in this order.

The light transmissive substrate 11 is a substrate of the organic EL element 10 and has light transmittance. The structural layer 12 is light transmissive and formed on the surface on the barrier layer 13 side in the stacking direction (refers to the surface opposite to the surface facing the light transmissive substrate 11 side, and so on). It has an uneven area and a planar area. The barrier layer 13 is light transmissive and prevents moisture and the like from entering. The first electrode layer 14 is light transmissive and serves as an anode. The functional layer 15 includes a light emitting layer. The second electrode layer 16 is a counter electrode of the first electrode layer 14. In addition, the light transmittance here means the property (translucency) which is transparent. For example, the light transmission in this specification means having light transmission at least in the wavelength of visible light region.
Further, as shown in FIG. 1, the light transmissive substrate 11, the structural layer 12, the barrier layer 13, and the first electrode layer 14 constitute a light extraction substrate 20.

As shown in FIG. 2, the light extraction substrate 20 according to the present embodiment has a concavo-convex region 21 and a planar region 22 formed by a plurality of concavo-convex portions 23 formed in the structural layer 12. That is, a plurality of uneven portions 23 are formed in the uneven region 21. The planar area 22 is composed of a planar portion (flat surface). By forming the concavo-convex portion 23 in the structural layer 12, as shown in FIG. 1, the concavo-convex portion corresponding to the concavo-convex portion 23 is also formed in the barrier layer 13 and the first electrode layer 14 which are the upper layers. Yes.
As shown in FIG. 1, the organic EL element 10 according to this embodiment is provided on the surface opposite to the surface on which the structural layer 12 of the light transmissive substrate 11 is formed (the back surface side of the light transmissive substrate 11). The light extraction lens layer 30 is provided.
Hereinafter, each part which comprises the organic EL element 10 is demonstrated in detail.

(Light transmissive substrate)
The light transmissive substrate 11 may be a plate-like member that transmits in the visible light region, and there is no particular limitation on the type of glass, plastic, or the like. Preferred examples of the light transmissive substrate 11 include a glass plate, a polymer plate, and a resin film.
Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz.

Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), polyphenylene sulfide, polysulfones, Li, polyether ketone imide, polyamide, fluorocarbon resin, nylon, polymethyl methacrylate, acrylic or polyarylates, and cycloolefin resins.

The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and the water vapor permeability (25 ± 0.5 ° C.) measured by a method according to JIS K 7129-1992. , Relative humidity (90 ± 2)% RH) is preferably 0.01 g / (m ² · 24 h) or less, and further, oxygen measured by a method according to JIS K 7126-1987. It is a high barrier film having a permeability of 1.0 × 10 ⁻³ cm ³ / (m ² · 24 h · atm) or less and a water vapor permeability of 1.0 × 10 ⁻³ g / (m ² · 24 h) or less. The water vapor permeability is more preferably 1.0 × 10 ⁻⁵ g / (m ² · 24 h) or less.

As a material for forming the barrier film, any material having a function of suppressing intrusion of moisture, oxygen, or the like that causes deterioration of the organic EL element 10 may be used. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. Can do. Furthermore, in order to improve the brittleness of the barrier film, it is more preferable to have a laminated structure of these inorganic layers and organic layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.
The method for forming the barrier film is not particularly limited. For example, the 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 A polymerization method, a plasma CVD (Chemical Vapor Deposition) method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but the atmospheric pressure plasma polymerization method described in JP-A-2004-68143 is used. Those are particularly preferred.

[Light extraction lens layer]
A light extraction lens layer 30 is appropriately provided as a light scattering or condensing layer on the surface of the light transmissive substrate 11 opposite to the surface on which the structural layer 12 is formed (the back surface side of the light transmissive substrate 11). The light extraction lens layer 30 includes a light transmissive sheet 31 having light transmissive properties, and a lens layer 32 provided on the surface of the light transmissive sheet 31. The lens layer 32 may be formed by forming the surface of the light transmissive sheet 31 in a microlens array-like structure, or may use a so-called condensing sheet. Thereby, the light extraction lens layer 30 can collect light in a specific direction, for example, in the front direction with respect to the light emitting surface of the element to increase the luminance in the specific direction.

Examples of the resin material constituting the light extraction lens layer 30 include low density or high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer. Polyolefin resins such as ethylene-norbornene copolymer, ethylene-domon copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ionomer resin; polyethylene terephthalate, polybutylene terephthalate, polyethylene Polyester resins such as phthalates; nylon-6, nylon-6,6, metaxylenediamine-adipic acid condensation polymers; amide resins such as polymethylmethacrylamide; acrylic resins such as polymethylmethacrylate; polystyrene Styrene-acrylonitrile resins such as styrene-acrylonitrile copolymer, styrene-acrylonitrile-butadiene copolymer, and polyacrylonitrile; Hydrophobized cellulose resins such as cellulose triacetate and cellulose diacetate; polyvinyl chloride, polyvinylidene chloride, polyfluoride Halogen-containing resins such as vinylidene fluoride and polytetrafluoroethylene; hydrogen-bonding resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and cellulose derivatives; polycarbonate resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins And engineering plastic resins such as polyphenylene oxide resin, polymethylene oxide resin, polyarylate resin, and liquid crystal resin.

The light extraction lens layer 30 may further improve the light scattering effect by adding fine particles to the resin material described above. As the fine particles contained in the light extraction lens layer 30, inorganic fine particles or organic fine particles can be used.
Examples of the fine particles include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, melamine-formalin condensate particles, polyurethane particles, polyester particles, silicone particles, fluorine particles, and copolymers thereof. , Clay compound particles such as smectite, kaolinite, talc, silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide, inorganic oxide particles such as strontium oxide, calcium carbonate, barium carbonate, barium chloride, sulfuric acid Examples thereof include inorganic fine particles such as barium, barium nitrate, barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, strontium nitrate, strontium hydroxide, and glass particles.

(Structural layer)
The structural layer 12 is light transmissive and is provided on the surface opposite to the light emitting surface of the light transmissive substrate 11 (the bonding surface of the light extraction lens layer 30 shown in FIG. 1). The structure layer 12 has an uneven region in which a plurality of uneven portions 23 are formed and a planar region including a flat portion on the surface on the first electrode layer 14 side. That is, in the structural layer 12, a part of the surface of the structural layer 12 on the first electrode layer 14 side is at least one uneven region, and the remaining part is a planar region. Each concavo-convex portion 23 is formed so as to have either a concave shape or a convex shape with respect to the plane portion. For example, each concavo-convex portion 23 is formed as a mountain shape (convex shape) or a valley shape (concave shape) with respect to the plane portion. But the shape of the uneven | corrugated | grooved part 23 is not limited to a mountain shape or a trough shape, A cylindrical shape or a cone shape may be a hemisphere. The shape in plan view is not limited to a circle. Further, it is not necessary that the shapes and dimensions of the uneven portions 23 are the same.

By forming an uneven region and a planar region on the surface of the structural layer 12 on the first electrode layer 14 side, the shape of the first electrode layer 14 formed on the structural layer 12 becomes the shape of the surface of the structural layer 12. Follow. In addition, when the functional layer 15 and the second electrode layer 16 are laminated on the first electrode layer 14, the surface of the second electrode layer 16 on the functional layer 15 side follows the surface shape of the first electrode layer 14. Inverted uneven regions and planar regions in which the uneven portions are also inverted are formed. Plasmon absorption can be suppressed by the inversion uneven region formed on the surface of the second electrode layer 16 on the functional layer 15 side. Further, since a part of the emitted light is reflected by the planar region formed on the second electrode layer 16, the light extraction efficiency is improved.

The area ratio of the uneven area to the area of the planar area of the structural layer 12 (area of the uneven area / area of the planar area) is preferably in the range of 1/4 to 10/1. When the area ratio is smaller than ¼, the plurality of uneven portions 23 in the uneven region is small, and the optical effect may not be reflected in the light extraction efficiency. On the other hand, when the area ratio is larger than 10/1, the planar area is small, the reflectivity of the second electrode is significantly lowered, and the light extraction efficiency may be reduced as a result.
The height H of the plurality of uneven portions 23 in the uneven region of the structural layer 12 is preferably 50 nm or more and 800 nm or less. When the height H of the plurality of uneven portions 23 is smaller than 50 nm, the surface plasmon resonance effect cannot be obtained because the height H of the unevenness is small. When the height H of the plurality of concavo-convex portions 23 is larger than 800 nm, the overall height of the functional layer is greatly exceeded, so that the uniformity of the functional layer is remarkably deteriorated, causing uneven light emission and short-circuiting. Defects may occur. The height H of the plurality of concavo-convex portions 23 is an absolute value of a change in the layer thickness direction with respect to the plane portion. For example, when the concavo-convex portion 23 is formed in a concave shape, it is the distance in the total thickness direction from the flat portion to the concave bottom portion of the concave shape in a side view.

Furthermore, the ratio (H / D) of the height H to the width D of the plurality of uneven portions 23 in the uneven region is preferably in the range of 1/5 to 8/5. This is because it is easy to configure each layer on the structural layer 12. Here, when the concavo-convex portion 23 of the concavo-convex region is formed so as to have a concave shape with respect to the flat portion of the flat region, the “ratio of the height H to the width D of the concavo-convex portion 23” The ratio of the height H to the width D of the recesses constituting In addition, when the concavo-convex portion 23 of the concavo-convex region is formed so as to have a convex shape with respect to the flat portion of the flat region, the “ratio of the height H to the width D of the concavo-convex portion 23” The ratio of the height H with respect to the width D of the convex part to comprise is said.

When the ratio of the height H to the width D of the convex portion (H / D) is outside the range of 1/5 to 8/5, the concave / convex portion 23 has a shape in which the inclined surface is raised or a fine surface to surface The shape of the boundary becomes clear, or the period of the unevenness is fine, and the top part and the groove part are shaped like dots. Therefore, in particular, when a sputtering method or a vapor deposition method is selected as a method for forming at least one of the first electrode layer 14, the functional layer 15, and the second electrode layer 16 on the structural layer 12, the same as the peripheral portion thereof. It is difficult to form a uniform film.
Moreover, it is preferable that the distance L between the adjacent uneven | corrugated parts 23 in the some uneven | corrugated | grooved part 23 formed in the uneven | corrugated area | region 21 is larger than the width | variety D of the uneven | corrugated part 23, and is 300 nm or more and 2 micrometers or less. Within the above range, the uneven width (distance L between adjacent uneven portions 23) can be maintained at about the emission wavelength, and the light emitted from the functional layer 15 travels to the second electrode layer 16 side. Thus, the effect of re-radiation by the conversion of the surface plasmon in the second electrode layer 16 can be obtained. That is, if it is smaller than 300 nm, light is confined because it is smaller than the emission wavelength, and if it is larger than 2 μm, propagation of surface plasmon occurs, and it attenuates without re-emission.

As the material constituting the structural layer 12, a resin is preferable. Examples of the resin include low density or high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-norbornene copolymer, ethylene -Polyolefin resins such as domon copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ionomer resin; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; nylon- 6, Nylon-6,6, Metaxylenediamine-Adipic acid condensation polymer; Amide resin such as polymethylmethacrylamide; Acrylic resin such as polymethylmethacrylate; Polystyrene, Styrene-acrylonitrile copolymer Styrene-acrylonitrile resins such as styrene-acrylonitrile-butadiene copolymer and polyacrylonitrile; Hydrophobized cellulose resins such as cellulose triacetate and cellulose diacetate; Polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polytetrafluoroethylene Halogen-containing resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymers, hydrogen bonding resins such as cellulose derivatives; polycarbonate resins, polysulfone resins, polyether sulfone resins, polyether ether ketone resins, polyphenylene oxide resins, polymethylene Examples thereof include engineering plastic resins such as oxide resins, polyarylate resins, and liquid crystal resins.

In the structure layer, fine particles may be added to adjust the refractive index and have a light scattering effect, and particles composed of inorganic fine particles or organic fine particles can be used. For example, acrylic particles, styrene particles, styrene acrylic particles and crosslinked products thereof, melamine-formalin condensate particles, polyurethane particles, polyester particles, silicone particles, fluorine particles, copolymers thereof, smectite, kaori Clay compound particles such as knight and talc, inorganic oxide particles such as silica, titanium oxide, alumina, silica alumina, zirconia, zinc oxide, barium oxide, strontium oxide, calcium carbonate, barium carbonate, barium chloride, barium sulfate, barium nitrate And inorganic fine particles such as barium hydroxide, aluminum hydroxide, strontium carbonate, strontium chloride, strontium sulfate, strontium nitrate, strontium hydroxide, and glass particles.

[Barrier layer]
The barrier layer 13 is a layer having a function of suppressing intrusion of moisture, oxygen, or the like that causes deterioration of the organic EL element 10, and a surface on the side opposite to the surface on the light transmissive substrate 11 side of the structural layer 12 as necessary. And at least one of them. FIG. 1 illustrates the case where the barrier layer 13 is provided only on the surface of the structural layer 12 opposite to the surface on the light transmissive substrate 11 side. The barrier layer 13 is not essential, but is preferably provided. By providing the barrier layer 13, the adhesion between the structural layer 12 and the first electrode layer 14 is improved. This is because the barrier layer 13 is present between the structural layer 12 and the first electrode layer 14, so that the first electrode layer 14 is not affected by the outgas from the structural layer 12 when the first electrode layer 14 is formed. This is because the film quality of the first electrode layer 14 is improved. By improving the film quality of the first electrode layer 14, initial defects (for example, dark spots) of the organic EL element 10 can be reduced. For this reason, by providing the barrier layer 13, the temporal stability of the organic EL element 10 can be improved.

As the barrier layer 13, for example, silicon oxide, silicon dioxide, silicon nitride or the like is used.
The method for forming the barrier layer 13 is not particularly limited. For example, the vacuum deposition method, the sputtering method, the reactive sputtering method, the molecular beam epitaxy method, the cluster ion beam method, the ion plating method, the plasma polymerization method, the atmospheric pressure plasma A polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but it is preferable that a film can be continuously formed by a formation method combined with a transparent electrode to be laminated next.
The thickness of the barrier layer 13 is, for example, 2 nm or more and 50 nm or less, preferably 2 nm or more and 20 nm or less. By providing the barrier layer 13, the effect of preventing intrusion of moisture and the like can be obtained. The barrier layer 13 is preferably a relatively thick film. Optically, when the refractive index of the barrier layer 13 is lower than the refractive index of the structural layer 12, a thin film is preferable in order to suppress reduction by total reflection light. However, if it is thinner than 2 nm, it cannot be formed uniformly on the surface of the structural layer 12, which is not preferable.

(Electrode layer)
Hereinafter, the first electrode layer 14 and the second electrode layer 16 will be described. Here, description will be made assuming that the first electrode layer 14 is an anode and the second electrode layer 16 is a cathode. However, actually, it is not limited to these examples.

(First electrode layer: anode)
As a material of the anode which is the 1st electrode layer 14, a metal, an alloy, a metal oxide, a conductive compound, or a mixture thereof is mentioned suitably, for example. As an anode material, for example, conductive oxide such as antimony or fluorine doped (added) tin oxide (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc. Metal such as conductive metal oxide, gold, silver, chromium and nickel, and a mixture or laminate of these metals and conductive metal oxide, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, Examples thereof include organic conductive materials such as polypyrrole, and laminates of these with ITO. Among these, a conductive metal oxide is preferable as the material of the anode, and ITO is particularly preferable from the viewpoint of productivity, high conductivity, transparency, and the like.

The anode may be, for example, (1) a wet method such as a printing method or a coating method, (2) a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or (3) a chemical method such as CVD or plasma CVD method. It can be formed on the substrate in accordance with a method appropriately selected from known methods such as a method in consideration of suitability with the material constituting the anode. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

The patterning for forming the anode may be performed by chemical etching using photolithography or the like, or may be performed by physical etching using a laser or the like. Further, it may be performed by vacuum deposition, sputtering or the like with overlapping masks, or by a lift-off method or a printing method.
When light emission is extracted from the anode, it is desirable that the transmittance be greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually in the range of 10 nm to 1000 nm, preferably in the range of 10 nm to 200 nm.

(Second electrode layer: cathode)
As a material of the cathode which is the second electrode layer 16, for example, a metal having a small work function (4 eV or less) (referred to as an electron injecting metal), an alloy electroconductive compound, and a mixture thereof are preferably exemplified. Examples of cathode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, Indium, lithium / aluminum mixtures, rare earth metals and the like can be mentioned. Among them, from the viewpoint of electron injectability and durability against oxidation, etc., as a cathode material, a mixture of an electron injectable metal and a second metal which is a stable metal having a larger work function value than this, for example, magnesium / silver Preference is given to mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like.
The cathode can be produced by forming a thin film made of a cathode material by a known method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm.

[Functional layer]
The functional layer 15 is a layer including a light emitting layer, and is a layer provided between the first electrode layer 14 and the second electrode layer 16. The first electrode layer 14, the functional layer 15, and the second electrode layer 16 can have various laminated structures.
Hereinafter, the laminated structure of the 1st electrode layer 14, the functional layer 15, and the 2nd electrode layer 16 is demonstrated concretely. As an example, the following layer configurations a) to p) are shown. Here, as described above, the first electrode layer 14 is an anode, and the second electrode layer 16 is a cathode. That is, all layers between the anode and the cathode are the functional layer 15. The symbol “/” indicates that the layers sandwiching the symbol “/” are stacked adjacent to each other. The configuration of the functional layer 15 and the laminated structure of the first electrode layer 14, the functional layer 15, and the second electrode layer 16 are not limited to the following layer configurations a) to p).

a) Anode / light emitting layer / cathode b) Anode / hole injection layer / light emitting layer / cathode c) Anode / hole injection layer / light emitting layer / electron injection layer / cathode d) Anode / hole injection layer / light emitting layer / Electron transport layer / cathode e) Anode / hole injection layer / emission layer / electron transport layer / electron injection layer / cathode f) Anode / hole transport layer / emission layer / cathode g) Anode / hole transport layer / emission layer / Electron injection layer / cathode h) anode / hole transport layer / light emitting layer / electron transport layer / cathode i) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode j) anode / hole Injection layer / hole transport layer / light emitting layer / cathode k) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode l) anode / hole injection layer / hole transport layer / light emitting layer / Electron transport layer / cathode m) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode n) anode / light emitting layer / electron injection layer / cathode ) Anode / light emitting layer / electron transport layer / cathode p) anode / light emitting layer / electron transport layer / electron injection layer / cathode Hereinafter, each layer (light emitting layer which constitutes the functional layer 15, injection layers, transport layer) will be described.

(Light emitting layer)
The light emitting layer is a layer that emits light by recombination of electrons and holes (holes) moving from the electrode, injection layer, or transport layer, and the light emitting portion may be in the layer of the light emitting layer. It may be the interface between the light emitting layer and the adjacent layer.
The total thickness of the light emitting layers is not particularly limited, but is preferably 2 nm or more and 5 μm or less, more preferably 2 nm or more and 200 nm or less, and particularly preferably 10 nm or more and 20 nm or less. This is because the uniformity of the film and the application of an unnecessary high voltage during light emission are prevented, and the stability of the emission color with respect to the drive current is improved.

The light emitting layer is at least one of a blue light emitting layer, a green light emitting layer, and a red light emitting layer. In the organic EL element 10, the blue light emitting layer has a light emission maximum wavelength in the range of 430 nm to 480 nm, the green light emitting layer has a light emission maximum wavelength in the range of 510 nm to 550 nm, and the red light emitting layer has a light emission maximum wavelength in the range of 600 nm to 640 nm. It is preferable that it is a monochromatic light emitting layer.
Further, the light emitting layer may be a layer formed by laminating these light emitting layers of at least three colors (blue light emitting layer, green light emitting layer, red light emitting layer) to form a white light emitting layer. Further, when a plurality of light emitting layers are stacked, a non-light emitting intermediate layer may be provided between the light emitting layers.

The light emitting layer of the organic EL element 10 according to this embodiment is preferably a white light emitting layer. That is, this embodiment is particularly effective when the light emitting layer of the organic EL element 10 is a white light emitting layer. Moreover, it is preferable that the illuminating device, planar light source, and display apparatus which concern on this embodiment contain a white light emitting layer. Therefore, it is preferable that the lighting device, the planar light source, and the display device according to the present embodiment have at least a part of the organic EL element 10 whose light emitting layer is a white light emitting layer.
The light emitting layer contains a light emitting host compound and a light emitting dopant compound such as a phosphorescent dopant or a fluorescent dopant.

Examples of the luminescent host compound include those having a basic skeleton such as a carbazole derivative, a triarylamine derivative, an aromatic derivative, a nitrogen-containing heterocyclic compound, a thiophene derivative, a furan derivative, an oligoarylene compound, or a carboline derivative or diaza. And carbazole derivatives.
Examples of fluorescent dopant compounds include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, Examples thereof include stilbene dyes, polythiophene dyes, and rare earth complex phosphors.

(Injection layer: hole injection layer, electron injection layer)
The injection layer is a layer provided between the electrode and the organic layer as necessary for lowering the driving voltage and improving the light emission luminance. The injection layer includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).
As described above, the hole injection layer is provided between the anode and the light emitting layer (for example, the above-described layer configurations b), c), d), e)), or the anode and the hole transport layer. (For example, between the layer configurations j), k), l), and m)) described above.
Further, the electron injection layer is provided between the cathode and the light emitting layer (for example, layer configurations (c), g), k), n)), or between the cathode and the electron transport layer (for example, a layer). Provided in configurations e), i), m), and p)).

As the hole injection layer, for example, a phthalocyanine buffer layer typified by copper phthalocyanine, an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, or a conductive polymer such as polyaniline (emeraldine) or polythiophene is used. Polymer buffer layer and the like.
Examples of the electron injection layer include a metal buffer layer typified by strontium and aluminum, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and aluminum oxide. An oxide buffer layer represented by
The hole injection layer and the electron injection layer are desirably very thin films, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although depending on the material.

(Blocking layer: hole blocking layer, electron blocking layer)
The blocking layer is a layer provided as necessary in addition to the basic constituent layer of the organic compound thin film. The blocking layer includes a hole blocking layer and an electron blocking layer.
The hole blocking layer has a function of an electron transport layer in a broad sense. The hole blocking layer is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and recombines electrons and holes by blocking holes while transporting electrons. Probability can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer as needed.

The film thicknesses of the hole blocking layer and the electron transport layer are preferably 3 nm or more and 100 nm or less, and more preferably 5 nm or more and 30 nm or less.
The hole blocking layer preferably contains the carbazole derivative, carboline derivative or diazacarbazole derivative mentioned as the host compound.
On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense. The electron blocking layer is made of a material that has a function of transporting holes but has a very small ability to transport electrons, and improves the probability of recombination of electrons and holes by blocking electrons while transporting holes. be able to. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed.

(Transport layer: hole transport layer, electron transport layer)
The transport layer is a layer provided as necessary for transporting holes or electrons. The transport layer includes a hole transport layer and an electron transport layer.
(Hole transport layer)
The hole transport layer is made of a hole transport material having a function of transporting holes. The hole injection layer and the electron blocking layer described above are included in the hole transport layer in a broad sense. The hole transport layer can be provided as a single layer or a plurality of layers.

The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. Examples of hole transport materials include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives. Fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers. The hole transport layer contains one or more of the above-described hole transport materials.
The hole transport layer is formed by thinning the above-described hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. The Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm or more and about 5 micrometers or less, Preferably they are 5 nm or more and 200 nm or less.

(Electron transport layer)
The electron transport layer is made of an electron transport material having a function of transporting electrons. The electron injection layer and hole blocking layer described above are included in the electron transport layer in a broad sense. The electron transport layer can be provided as a single layer or a plurality of layers. The electron transport layer is provided adjacent to the cathode side of the light emitting layer.
Any electron transport material (also serving as a hole blocking material) used for the electron transport layer may have a function of transmitting electrons injected from the cathode to the light emitting layer. For example, any one of conventionally known compounds can be selected and used. Examples of the electron transport material include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and the like. Furthermore, in the oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

Further, as an electron transporting material, a metal complex of an 8-quinolinol derivative such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo- 8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metal of these metal complexes A metal complex in which In, Mg, Cu, Ca, Sn, Ga, or Pb is replaced can also be used as an electron transporting material. In addition, metal-free or metal phthalocyanine, or a material whose terminal is substituted with an alkyl group or a sulfonic acid group can be preferably used. Further, the distyrylpyrazine derivatives exemplified as the material for the light emitting layer can also be used as the electron transporting material. Further, similarly to the hole injection layer and the hole transport layer, inorganic semiconductors such as n-type-Si and n-type-SiC can also be used as the electron transport material. The electron transport layer contains one or more materials among the electron transport materials described above. Further, an electron transport layer having a high n property doped with impurities can also be used.
The electron transport layer is formed by thinning the above-described electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, it is the range of 5 nm or more and 5 micrometers or less, Preferably it is chosen in the range of 5 nm or more and 200 nm or less.

(Sealing member)
The display area of the organic EL element 10 is covered and sealed with a sealing member. Examples of the sealing means include a method of bonding the sealing member, the electrode, and the support substrate with an adhesive.
The sealing member should just be arrange | positioned so that the display area of the organic EL element 10 may be covered, and may be concave plate shape or flat plate shape. Moreover, the sealing member does not ask | require in particular the presence or absence of transparency and electrical insulation.
Examples of the sealing member include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda-lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum.

Examples of the adhesive used for sealing include photo-curing and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture-curing types such as 2-cyanoacrylates. Mention may be made of adhesives. Moreover, heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.
Note that the organic EL element 10 may be deteriorated by heat treatment. For this reason, it is preferable to use a material that can be adhesively cured in a temperature range from room temperature to 80 ° C. as the adhesive. Further, an adhesive in which a desiccant is dispersed may be used. Application | coating of the adhesive agent to a sealing part may use commercially available dispenser, and may print like screen printing.

In the gap between the sealing member and the display area of the organic EL element 10, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil is injected in the gas phase and the liquid phase. Is preferred. Further, the gap between the sealing member and the display area of the organic EL element 10 can be evacuated. Furthermore, a hygroscopic compound can also be enclosed inside the sealing member.
Examples of the hygroscopic compound include metal oxides (for example, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide) and sulfates (for example, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide etc.), perchloric acids (eg perchloric acid) Barium, magnesium perchlorate, etc.), and sulfates, metal halides, and perchloric acids are preferably anhydrous salts.

[Use]
The organic EL element 10 according to the present embodiment can be used as a display device, a display, or various light sources. For example, lighting devices (home lighting, interior lighting), clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light Examples include a light source of a sensor. An example of the light source is a planar light source. Although the use of the organic EL element 10 is not limited to this, it can be effectively used especially as a backlight of a liquid crystal display device and a light source for illumination.

An example of the structure of the lighting device is shown in FIG. As shown in FIG. 3, the configuration example of the illumination device includes a light transmissive substrate 11, a structural layer 12, a first electrode (anode) 14, a functional layer 15, and a second electrode (cathode) 16 from the light emission side. , A hygroscopic member 1202, and a sealing member 1204. 3 is an external connection terminal. In this configuration example, the configuration from the light transmissive substrate 11 to the second electrode (cathode) 16 corresponds to the organic EL element 10 described above. Moreover, the planar light source of this embodiment can also be set as the structure similar to an illuminating device.
Here, manufacture of the illuminating device and planar light source of this embodiment can be implemented by adding a well-known process to the manufacturing method of the above-mentioned organic EL element. The anode part of the lighting device or the planar light source may include a driving part such as a silicon driving substrate.

Next, an example of the display device of this embodiment is shown in FIG. As shown in FIG. 4, the display device has a light transmissive substrate 11, a color filter layer (for example, RGB color filter layer) 102, a structural layer 12, a first electrode (anode) 14 and a function from the display side of the device. A layer 15 and a second electrode (cathode) 16 are included. In the configuration example of FIG. 4, portions other than the color filter layer 102 correspond to the above-described organic EL element.
The display device according to this embodiment can be manufactured by adding a known process to the above-described method for manufacturing an organic EL element. For example, the color filter layer 102 can be formed using any conventionally known method such as a spin coating method or a vapor deposition method.

An example embodying the above-described embodiment will be described together with a comparative example as a comparison target.
In the present embodiment, each uneven portion 23 in the uneven region of the structural layer 12 is selected to have a concave shape or a convex shape in each condition, and according to the height H, it becomes a circular peak or valley in plan view. The width D (corresponding to the diameter of the circle) was formed. In addition, the uneven portions 23 are randomly arranged, and the average distance L between the uneven portions 23 is determined by measuring images of the uneven portions 23 at 10 positions of the uneven regions using a scanning probe microscope. The value which can be calculated by measuring the interval of any adjacent convex shape or concave shape of 10 or more points and obtaining the average was adopted.

<Example 1>
(Production of light extraction substrate)
First, a light extraction substrate in which the light transmissive substrate 11, the structure layer 12, and the light transmissive first electrode layer 14 are laminated in this order is manufactured.
As the light-transmitting substrate 11, a washed alkali-free glass plate having a thickness of 0.7 mm and a size of 30 mm × 40 mm was used.

On this light-transmitting substrate 11, a UV (ultraviolet) curable acrylic resin is formed as a first layer with a film thickness of 2 μm by a spin coater and heated on a hot plate at 90 ° C. for 2 minutes to form a resin layer. Formed. Subsequently, after laminating the surface of the resin layer coated and formed on the light-transmitting substrate 11 so as to press a film plate having a planar region and a fine concavo-convex pattern region (concavo-convex region), it is 150 mJ / cm ² with a UV lamp. Irradiation was performed, and the film plate was peeled off to form the structural layer 12 having a plurality of uneven portions 23 and a flat portion on the surface. As a result, an uneven area having a convex circular mountain having a height of H100 nm and a width of D100 nm and having an average distance L of 400 nm on the surface of the structural layer 12 is obtained as a total area of the uneven area in the total area. Ratio (ratio occupied by the uneven area) / total area ratio (area occupied by the planar area) of the planar area was 50% / 50%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Next, an ITO layer, which is a transparent electrode, is formed on the surface of the structural layer 12 as a light transmissive first electrode layer 14 (anode) by a sputtering method so as to have a thickness of 150 nm, and then patterned. went.

(Production of organic EL element)
On the surface of the first electrode layer 14, a hole transport layer, a light-emitting layer, and an electron transport layer were laminated as an organic layer of the functional layer 15 by an evaporation method.
The hole transport layer was formed with a thickness of 35 nm using 4,4 ′, 4 ″ -tris (9-carbazole) triphenylamine. The light-emitting layer includes a layer having a thickness of 15 nm using 4,4 ′, 4 ″ -tris (9-carbazole) triphenylamine doped with a tris (2-phenylpyridinato) iridium (III) complex, and tris ( It was formed with a 15 nm thick layer using 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene doped with 2-phenylpyridinato) iridium (III) complex.

The electron transport layer was formed with a thickness of 65 nm using 1,3,5-tris (N-phenylbenzimidazol-2-yl) benzene.
Furthermore, a lithium fluoride layer (thickness: 1.5 nm) was deposited as an electron injection layer on the surface of the organic layer. Thereby, the functional layer 15 including the light emitting layer was formed.
Finally, a metal electrode (aluminum, thickness: 50 nm) was formed on the surface of the functional layer 15 by a vapor deposition method.

Subsequently, a prism lens sheet in which a lens surface (lens layer 32) having a hemispherical microlens having a diameter of 5 μm and a cross prism structure having a vertical angle of 89 degrees with a pitch of 5 μm is formed on the surface of the PET film (light-transmitting sheet 31). Was bonded to the light-transmitting substrate 11 through an adhesive to form a light extraction lens layer 30. At this time, the prism lens sheet is bonded to the rear surface of the surface of the light transmissive substrate 11 where the structural layer 12 is formed so that the rear surface of the lens surface faces the light transmissive substrate 11, and the lens surface becomes the front surface. I did it.
Thereby, as shown in FIG. 1, the structural layer 12, the first electrode layer 14, the functional layer 15, and the second electrode layer 16 are laminated in this order on the surface (one surface) of the light transmissive substrate 11. The organic EL element 10 in which the light extraction lens layer 30 was formed on the other surface was obtained.

<Example 2>
On the surface of the structural layer 12, an uneven region having a convex circular mountain having a height of H100 nm and a width of D100 nm and having an average distance L of 400 nm is represented by a ratio of the total area of the uneven region to the total area / The total area ratio of the planar regions was 20% / 80%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Example 3>
On the surface of the structural layer 12, an uneven region having a convex circular mountain having a height of H100 nm and a width of D100 nm and having an average distance L of 400 nm is represented by a ratio of the total area of the uneven region to the total area / The total area ratio of the planar regions was 91% / 9%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Example 4>
On the surface of the structural layer 12, a concave / convex area having a pattern of concave circular peaks with a height of H50 nm and a width of D250 nm and an average distance L between the peaks of 300 nm is a ratio of the total area of the concave / convex areas / plane. The total area ratio was 50% / 50%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Example 5>
On the surface of the structural layer 12, a concave / convex region having a pattern of concave circular ridges having a height of H100 nm and a width of D250 nm and having an average distance L between the ridges of 400 nm, a ratio of the total area of the concavo-convex regions to the total area / plane The total area ratio was 50% / 50%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Example 6>
On the surface of the structural layer 12, a concave / convex area having a height of H250 nm and a width of D400 nm and having a pattern in which the average distance L between the peaks is 600 nm is a ratio of the total area of the concave / convex area / plane. The total area ratio was 50% / 50%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Example 7>
On the surface of the structural layer 12, an uneven region having a convex circular mountain having a height of H500 nm and a width of D500 nm and having an average distance L between the peaks of 1000 nm is defined as a ratio of the total area of the uneven region to the total area / The total area ratio of the planar regions was 50% / 50%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Example 8>
On the surface of the structural layer 12, an uneven region having a pattern of convex circular peaks with a height of H 800 nm and a width of D 500 nm and an average distance L between the peaks of 2000 nm is defined as a ratio of the total area of the uneven regions to the total area / The total area ratio of the planar regions was 50% / 50%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Comparative Example 1>
On the light-transmitting substrate 11, a UV curable acrylic resin was formed as a first layer with a film thickness of 2 μm by a spin coater, and heated on a hot plate at 90 ° C. for 2 minutes to form a resin layer. Thereafter, the light-transmitting substrate 11 on which the resin layer was formed was placed in an N ₂ purged box and irradiated with a UV lamp at 150 mJ / cm ² to form a structural layer 12 with high smoothness.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Comparative example 2>
On the surface of the structural layer 12, an uneven region having a pattern of convex circular peaks with a height H of 100 nm and a width D of 600 nm and an average distance L between the peaks of 800 nm is defined as a ratio of the total area of the uneven regions to the total area / The total area ratio of the planar areas was 15% / 85%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Comparative Example 3>
On the surface of the structural layer 12, an uneven region having a pattern of convex circular peaks with a height H of 100 nm and a width D of 600 nm and an average distance L between the peaks of 800 nm is defined as a ratio of the total area of the uneven regions to the total area / The total area ratio of the planar regions was 95% / 5%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Comparative example 4>
On the surface of the structural layer 12, an uneven region having a pattern of convex circular peaks with a height H of 30 nm and a width D of 180 nm and an average distance L between the peaks of 250 nm is defined as a ratio of the total area of the uneven regions to the total area / The total area ratio of the planar areas was 15% / 85%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Comparative Example 5>
On the surface of the structural layer 12, an uneven region having a pattern of convex circular peaks with a height of H900 nm and a width of D500 nm and an average distance L between the peaks of 2500 nm is a ratio of the total area of the uneven regions in the total area / The total area ratio of the planar areas was 15% / 85%. The shape of the surface of the structural layer 12 was confirmed with a scanning probe microscope.
Except this, it carried out similarly to Example 1, and created the organic EL element 10. FIG.

<Evaluation>
For each of the organic EL elements 10 of Examples 1 to 8 and Comparative Examples 1 to 5, the light extraction efficiency was measured and a short circuit was confirmed. Table 1 below shows the details of the structure of the structural layer 12 in each of the organic EL elements 10 of Examples 1 to 8 and Comparative Examples 1 to 5, and the results of evaluating the light extraction efficiency ratio and the presence or absence of a short circuit. Indicates.

Here, in measuring the light extraction efficiency, a current density of 20 mA / cm ² from a direct current (DC) power source was applied to each of the organic EL elements 10 of Examples 1 to 8 and Comparative Examples 1 to 5. The constant radiant current was applied, the total emitted radiant flux was measured with an integrating sphere, and the light extraction efficiency was determined based on the measurement result.
In confirming the short circuit, the current is increased by increasing the voltage when the above-described constant current is applied to each of the organic EL elements 10 of Examples 1 to 8 and Comparative Examples 1 to 5. The case where the value increased was evaluated as “no short” (good), and the case where the current value did not increase even when the voltage was raised was evaluated as “short” (defective).

In Table 1, the light extraction efficiency ratio indicates the light extraction efficiency of the organic EL element 10 including the light transmissive substrate 11 in which the first structural layer 12 of Comparative Example 1 has no uneven region and the planar region is 100%. The standard was 1.00. The light extraction efficiencies of Examples 1 to 8 and Comparative Examples 2 to 5 are expressed as relative values to the light extraction efficiency of the organic EL element 10 of Comparative Example 1. The light extraction effect is 1.50 or more.
As shown in Table 1, in the organic EL elements 10 of Examples 1 to 8, it was confirmed that the light extraction efficiency showed a high value from 1.52 to 1.78. Thus, it was found that the light extraction efficiency was improved in the organic EL elements 10 of Examples 1 to 4 as compared with the organic EL element 10 of Comparative Example 1.

This is because the concavo-convex shape formed on the surface of the second electrode layer 16 on the functional layer 15 side by forming the convex portion or the concave portion in the structural layer 12 has a good balance between suppression of plasmon absorption and reflection of light emission. The extraction efficiency is estimated to have improved.
In addition, the organic EL elements 10 of Examples 1 to 8 were good without any short circuit.
This is because the height H with respect to the unevenness width D is not too high, the film quality of the first electrode layer 14 made of the ITO film is uniformly formed, and the organic layer including the light emitting layer is further uniformly formed thereon. It is presumed that a defect in which the second electrode layer 16 and the first electrode layer 14 thereon are partially in contact did not occur.

In Comparative Example 2, the light extraction efficiency was the same as in Comparative Example 1, and no effect was obtained. Moreover, no short circuit occurred.
This is presumed that the effect of improving the light extraction efficiency could not be obtained because the surface layer of the structural layer 12 had few uneven regions and many planar regions.
In Comparative Example 3, the light extraction efficiency showed a slightly high value of 1.40. Moreover, no short circuit occurred.
This is because the concavo-convex region of the structural layer 12 has a certain effect on the suppression of plasmon absorption and the reflection of light emission. However, since the planar region is small, reflection from the emitted light is small, and as a result, overall It is estimated that the improvement in efficiency is not sufficient.

In Comparative Example 4, the light extraction efficiency was the same as in Comparative Example 1, and no effect was obtained. Moreover, no short circuit occurred.
This is presumed that the effect of improving the light extraction efficiency could not be obtained because the surface layer of the structural layer 12 had few uneven regions and many planar regions.
In Comparative Example 5, the light extraction efficiency was lower than in Comparative Example 1, and no effect was obtained. In addition, a current leak occurred from the start of the measurement, and short-circuited after the measurement.
This is because the height H of the concavo-convex portion 23 of the concavo-convex region on the surface of the structural layer 12 is very large with respect to the width D, and thus the shape becomes a standing shape. The formation of the deposited film was not progressed, and it was thinner than the peripheral functional layer 15 or was missing. Since the first electrode layer 14 is exposed to the second electrode layer 16 side and a minute bipolar electrode energization region is generated, an excessive current flows, and a short circuit occurs later to cause a light emission failure, and the light emission region is uniform. It is presumed that no carriers (charge carriers) such as electrons or holes flow in the light, resulting in a decrease in luminous efficiency.

As described above, the organic EL element 10 according to this embodiment includes the structural layer 12, the light-transmissive first electrode layer 14, the functional layer 15 including the light-emitting layer, the first layer on the light-transmissive substrate 11. Two electrode layers 16 are laminated in this order. Further, the structure layer 12 is provided with an uneven region and a planar region. Thereby, it turned out that the light extraction efficiency of the organic EL element 10 can be improved, light emission unevenness can be reduced, and light emission quality can be improved.

As described above, the entire content of Japanese Patent Application No. 2016-029008 (filed on Feb. 18, 2016), to which the present application claims priority, forms part of the present disclosure by reference.
Further, although the present invention has been described by each embodiment, the scope of the present invention is not limited to the illustrated and described exemplary embodiments, and the same effects as those intended by the present invention are brought about. All embodiments are also included. Further, the scope of the present invention is not limited to the combinations of features of the invention defined by the claims, but can be defined by any desired combination of specific features out of every disclosed feature.

The organic EL device of the present invention can suppress uneven light emission and obtain good stability over time while maintaining good light extraction efficiency. For this reason, the organic EL element of the present invention is suitable for various uses such as a display, a planar light source, and a lighting device that require uniform light emission, and can contribute to energy saving.

DESCRIPTION OF SYMBOLS 10 Organic EL element 11 Light transmissive board | substrate 12 Structural layer 13 Barrier layer 14 1st electrode layer 15 Functional layer 16 2nd electrode layer 20 Light extraction board | substrate 21 Uneven region 22 Planar region 23 Uneven portion 30 Light extraction lens layer 31 Light transmittance Sheet 32 Lens layer H Height D Width L Distance between uneven parts (average distance)

Claims

A structural layer, a first electrode layer, a functional layer, and a second electrode layer are formed in this order on one surface side of the substrate having optical transparency,
The structural layer is light transmissive, and has at least two types of regions, a concavo-convex region composed of a plurality of concavo-convex portions formed on a surface opposite to the substrate and a planar region composed of a flat portion,
The first electrode layer is light transmissive,
The functional layer includes a light emitting layer,
An organic EL device characterized by that.
2. The area ratio of the area of the uneven area to the area of the planar area (area of the uneven area / area of the planar area) is from 1/4 to 10/1. Organic EL element.
3. The organic EL element according to claim 2, wherein the height of the uneven portion of the uneven region is 50 nm or more and 800 nm or less.
The ratio of the height of the uneven portion to the width of the uneven portion (height of the uneven portion / width of the uneven portion) is 1/5 to 8/5. The organic EL element of description.
5. The organic EL according to claim 4, wherein a distance between adjacent uneven portions of the plurality of uneven portions formed in the uneven region is larger than a width of the uneven portion and is not less than 300 nm and not more than 2 μm. element.
6. The organic EL device according to claim 1, further comprising a barrier layer between the structural layer and the first electrode layer.
The organic EL element according to any one of claims 1 to 6, further comprising a light extraction lens layer on a surface of the substrate opposite to a surface on which the structural layer is formed.
An illumination device having at least a part of the organic EL element according to any one of claims 1 to 7.
A planar light source having at least a part of the organic EL element according to any one of claims 1 to 7.
A display device having at least a part of the organic EL element according to any one of claims 1 to 7.