WO2019187265A1 - Organic el element, organic el lighting device, and light extraction film for suppressing coloring of organic el element - Google Patents

Abstract

The present invention provides an organic EL element that can suppress coloring and enhance transparency. This organic EL element of the present invention is characterized by comprising a first substrate, a positive electrode, an organic EL layer, a negative electrode, a second substrate, and a light extraction layer, wherein the first substrate, the positive electrode, the organic EL layer, the negative electrode, and the second substrate are stacked in this order, the organic EL layer comprises a light emitting layer, and the light extraction layer is disposed on at least one among the first substrate and the second substrate on at least one among: a surface on which the positive electrode, the organic EL layer, and the negative electrode are stacked; and a surface on an opposite side to the surface on which the positive electrode, the organic EL layer, and the negative electrode are stacked.

Description

Organic EL element, organic EL lighting device, and light extraction film for suppressing coloring of organic EL element

The present invention relates to an organic EL element, an organic EL lighting device, and a light extraction film that suppresses coloring of the organic EL element.

As an organic EL element having high design properties, an organic EL element having transparency and capable of extracting light from both sides is known (Patent Document 1). The organic EL element can be formed by using a transparent material for the substrate and the electrode.

Japanese Patent Laid-Open No. 10-144475

However, the double-sided organic EL device actually has a problem that coloring occurs and the color looks dark.

Therefore, an object of the present invention is to suppress coloring of the organic EL element and improve transparency.

In order to achieve the above object, the organic EL device of the present invention comprises:
Including a first substrate, an anode, an organic EL layer, a cathode, a second substrate, and a light extraction layer;
The first substrate, the anode, the organic EL layer, the cathode, and the second substrate are laminated in this order,
The organic EL layer includes a light emitting layer,
The light extraction layer includes at least one of the first substrate and the second substrate, the surface on which the anode, the organic EL layer, and the cathode are stacked, or the anode, the organic EL layer, The cathode is disposed on at least one side opposite to the side on which the cathode is laminated.

The organic EL lighting device of the present invention includes the organic EL element of the present invention.

The light extraction film for suppressing coloring of the organic EL device of the present invention is characterized by including at least one of a microstructure layer and a refractive index adjustment layer.

According to the present invention, coloring of the organic EL element can be suppressed and transparency can be improved.

FIG. 1 is a schematic view (cross-sectional view) of the organic EL element according to Embodiment 1 seen from the side. FIG. 2 is a schematic view (cross-sectional view) of a conventional organic EL element as seen from the side. FIG. 3 is a schematic view (cross-sectional view) of the organic EL element in Embodiment 2 as viewed from the side.

Next, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited or restricted by the following embodiments. In the following drawings, the same parts are denoted by the same reference numerals. The description in each embodiment can mutually use each other. Further, the configurations of the embodiments can be combined unless otherwise specified. Further, in the drawings, for convenience of explanation, there is a portion where the structure of each portion is simplified as appropriate, and the dimensional ratio of each portion may be schematically shown, unlike the actual case.

(Embodiment 1)
FIG. 1 is a schematic view (cross-sectional view) of the organic EL element 1 according to this embodiment as viewed from the side. As shown in FIG. 1, the organic EL element 1 of the present embodiment is a double-sided light emitting organic EL element, and includes a substrate 10 that is the first substrate, an anode 11, an organic EL layer 12, and a cathode 13. A sealing layer 14, a sealing substrate 15 that is the second substrate, and a microstructure layer 16 that is a light extraction layer, which are stacked in the order described above. In the present embodiment, the outside of the organic EL element 1 is referred to as the atmosphere. The direction in which light is emitted from the organic EL element 1, that is, the upward direction and the downward direction in FIG. The organic EL layer 12 includes a hole injection layer 121, a hole transport layer 122, a light emitting layer 123, an electron transport layer 124, and an electron injection layer 125, which are stacked in the above order. Note that the hole injection layer 121, the hole transport layer 122, the electron transport layer 124, the electron injection layer 125, and the sealing layer 14 are not essential constituent elements, and may be included in the organic EL element 1. It does not have to be included. Further, in the organic EL element 1, the anode 11 and the cathode 13 may be laminated in the reverse order.

In the present embodiment, the substrate 10, the anode 11, the organic EL layer 12, the cathode 13, the sealing layer 14, the sealing substrate 15, and the microstructure layer 16 are formed using a material having transparency.

The material for forming the substrate 10 is, for example, polyester such as polyethylene naphthalate or polyethylene terephthalate; polyimide; acrylic resin such as polymethyl methacrylate, polyethyl methacrylate, polymethyl acrylate, or polyethyl acrylate; polyethersulfone Polycarbonate; alkali-free glass, soda glass, soda lime glass, borosilicate glass, aluminosilicate glass, quartz glass and the like. The magnitude | size (length and width) of the board | substrate 10 is not restrict | limited in particular, For example, what is necessary is just to set suitably according to the magnitude | size of the desired organic EL element 1. FIG. The thickness of the substrate 10 is not particularly limited, and can be appropriately set according to the forming material, the use environment, etc., and is, for example, 1 mm or less.

For example, the substrate 10 may be formed by further forming a protective layer on a substrate using the above material. For example, the protective layer preferably has a gas barrier property in order to prevent intrusion of water, oxygen and the like. The material for forming the protective layer is, for example, at least one selected from the group consisting of an inorganic oxide film, an inorganic oxynitride film, an inorganic nitride film, and an inorganic fluoride film from the viewpoint of gas barrier properties and light transmittance. Can be used. Specifically, for example, silicon oxynitride film (SiO _x N _y ), silicon oxide film (SiO ₂ ), silicon nitride film (SiN _x ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), And magnesium fluoride (MgF ₂ ). For example, the protective layer may be a single layer or a plurality of layers. In the latter case, for example, a plurality of the gas barrier films can be stacked in order to improve the gas barrier characteristics. The protective layer can be formed by, for example, chemical vapor deposition (CVD) and reactive sputtering (reactive sputtering).

When the organic EL element 1 having flexibility is used, a buffer layer may be further laminated on the protective layer in order to make the protective layer flexible. As a material for forming the buffer layer, from the viewpoint of permeability, flexibility, and thermal stability, for example, epoxy resin, silicone resin, acrylic resin, imide resin, amide resin, urethane system, And an olefin resin, an organic-inorganic hybrid material obtained by adding an inorganic material such as silica to the resin material, and an inorganic material such as a coating type silicon oxide film. For example, the protective layer and the buffer layer may be alternately stacked.

Examples of the material for forming the anode 11 include indium tin oxide (ITO). The anode 11 can be formed by, for example, a sputtering method.

The light emitting layer 123 is a layer that recombines electrons and holes injected from the electrode to emit fluorescence, phosphorescence, and the like. The light emitting layer 123 includes a light emitting material. Examples of the light emitting material include tris (8-quinolinol) aluminum complex (Alq ₃ ), bisdiphenylvinylbiphenyl (BDPVBi), 1,3-bis (pt-butylphenyl-1,3,4-oxadiazole) Yl) phenyl (OXD-7), N, N′-bis (2,5-di-t-butylphenyl) perylenetetracarboxylic acid diimide (BPPC), 1,4 bis (Np-tolyl-N-4) Examples thereof include low molecular compounds such as-(4-methylstyryl) phenylamino) naphthalene, and high molecular compounds such as polyphenylene vinylene-based polymers.

In addition, the light emitting material may be, for example, a material composed of a two-component system of a host and a dopant, in which excited state energy generated by the host molecule moves to the dopant molecule and the dopant molecule emits light. Specifically, such a light-emitting material is, for example, a quinolinol metal complex such as a host Alq ₃ and a dopant 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran ( DCM), quinacridone derivatives such as 2,3-quinacridone, or those doped with a coumarin derivative such as 3- (2′-benzothiazole) -7-diethylaminocoumarin, bis (2- Methyl-8-hydroxyquinoline) -4-phenylphenol-aluminum complex doped with a condensed polycyclic aromatic compound such as perylene as a dopant, or 4,4′-bis (host hole transport layer material) m-tolylphenylamino) biphenyl (TPD) doped with rubrene as a dopant, host 4,4 ′ A carbazole compound such as biscarbazolylbiphenyl (CBP) and 4,4′-bis (9-carbazolyl) -2,2′-dimethylbiphenyl (CDBP), a dopant platinum complex, tris- (2 ferrinylpyridine) ) Iridium Complex (Ir (ppy) ₃ ), (Bis (4,6-di-fluorophenyl) -pyridinate-N, C2 ′) Picolinate Iridium Complex (FIr (pic)), (Bis (2- (2 ′ -Iridium complexes such as benzo (4,5-α) thienyl) pyridinate-N, C2 ′) (acetylacetonate) iridium complex (Btp ₂ Ir (acac)), Ir (pic) ₃ , Bt ₂ Ir (acac) The light emitting material can be appropriately selected according to the target light emission color of the organic EL element 1, for example.

The light emitting layer 123 can be formed by, for example, physical vapor deposition (PVD), and specifically, for example, can be formed by vacuum deposition using resistance overheating. The light emitting layer 123 can be formed, for example, by doping (co-depositing) each color dopant (guest material) into the host material.

Examples of the material for forming the hole injection layer 121 include arylamine derivatives such as copper phthalocyanine (Cu—Pc), m-MTDATA, 2-TNATA, and starburst aromatic amines such as TCTA, spiro-TAD, 2,3,6,7,10,11-Hexacyano-1,4,5,8,9,12-Hexaazatriphenylene (HAT-CN), and hole-injecting organic materials such as vanadium pentoxide and trioxide Examples include those chemically doped with molybdenum or the like. Examples of the material for forming the hole transport layer 122 include bis (di (p-tolyl) aminophenyl) -1,1-cyclohexane, N, N′-diphenyl-NN—bis (1-naphthyl)- 1,1′-biphenyl) -4,4′-diamine (α-NPD), 4,4′-bis (m-tolylphenylamino) biphenyl (TPD), triphenyldiamines such as TAPC, and triphenylamine Further, TPTR, TPTE, NTPA, starburst type aromatic amines and the like which are increased in quantity are listed. Examples of the material for forming the electron transport layer 124 include 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (Bu-PBD), 2,9 -Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 1,3-bis (pt-butylphenyl-1,3,4-oxadiazolyl) phenyl (OXD-7), etc. Examples thereof include oxadiazole derivatives, triazole derivatives, quinolinol-based metal complexes, and triphenyldiamine derivatives. Examples of the material for forming the electron injection layer 125 include fluorides and oxides of alkali metals such as lithium and cesium, alkaline earth metals such as calcium, and electron transport materials such as BCP, and alkalis such as cesium. Examples thereof include those doped with metals and alkaline earth metals, magnesium silver, lithium aluminum alloys, and the like.

The organic EL layer 12 may further include, for example, a carrier block layer that blocks holes or electrons and increases luminous efficiency. The carrier block layer is, for example, an electron block layer and a hole block layer. Examples of the material for the hole blocking layer include 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), triphenyldiamine derivatives, triazole derivatives, and the like.

The hole injection layer 121, the hole transport layer 122, the electron transport layer 124, the electron injection layer 125, and the carrier block layer can be formed by, for example, physical vapor deposition (PVD). It can be formed by a vacuum vapor deposition method using overheating.

Examples of the material for forming the cathode 13 include aluminum, silver, AlNd, and MoNb alloy. The cathode 13 can be formed by, for example, physical vapor deposition (PVD), and specifically, can be formed by, for example, vacuum deposition using an electron beam and sputtering.

The sealing layer 14 is, for example, an adhesive layer and a filling layer.

The adhesive layer is a layer including a bonding material between substrates, for example. Examples of the bonding material include those using epoxy, acrylic and silicone adhesives, and pressure-sensitive adhesives.

The filler layer is a layer containing a filler such as gas and resin, for example. The gas is, for example, an inert gas such as nitrogen, argon, or neon, and a rare gas. Examples of the resin include epoxy resins, silicone resins, acrylic resins, imide resins, amide resins, urethane resins, and olefin resins.

The sealing substrate 15 seals the organic EL element 1. Examples of the material for forming the sealing substrate 15 include transparent glasses such as alkali-free glass and soda glass, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PES (polyethersulfone), PI (polyimide). And films such as COP (cycloolefin polymer), sheets, resin substrates, and the like. Also in the sealing substrate 15, for example, the protective layer and the buffer layer can be formed.

The microstructure layer 16 is a layer for preventing reflection of light at the interface of the organic EL element 1 and thereby improving extraction of light from the organic EL element 1 to the atmosphere.

As described above, until now, even in a double-sided light emitting organic EL element, in practice, coloring has occurred and the color appears to be dark. On the other hand, as a result of diligent research, the present inventors, as shown in FIG. 2, do not emit light to the atmosphere due to reflection of light at the interface of the element, in particular, at the interface between the substrate of the element and the atmosphere. In addition, since the reflection occurs on the front side and the back side of the element and multiple reflection occurs, the organic material in the element is repeatedly passed before the light is emitted to the atmosphere side, The inventors have obtained knowledge that light absorption by the organic material or the like is repeated and the coloring of the organic EL element is increased. And it came to discover that coloring of an organic EL element can be suppressed by preventing reflection of the light in the interface of an element from this. According to the present invention, by providing a light extraction layer at the interface, reflection of light at the interface can be prevented, and extraction of light from the organic EL element 1 to the atmosphere can be improved. For this reason, the coloring of the organic EL element 1 can be suppressed and the transparency of the organic EL element 1 can be improved.

As shown in FIG. 1, the microstructure layer 16 is configured by forming a plurality of microstructures 161 in a planarization layer 162. More specifically, the microstructure 161 is formed on the sealing substrate 15, and the microstructure layer 16 is formed by planarization and sealing with the planarization layer 162. Note that the planarization layer 162 is not an essential component, and may or may not be included in the microstructure layer 16. Specifically, for example, when the microstructure layer 16 is provided on the surface of the sealing substrate 15 on the atmosphere side, the planarization layer 162 may not be included. Since the microstructure layer 16 does not include the planarization layer 162, for example, adjustment of the refractive index in the planarization layer 162 becomes unnecessary.

In FIG. 1, the microstructure layer 16 is formed on the sealing substrate 15, but is not limited thereto, and may be formed on the substrate 10, for example. Further, the microstructure layer 16 may be formed on both the sealing substrate 15 and the substrate 10. For example, when the microstructure layer 16 is formed on the substrate 10, in the above description and the following description, “sealing substrate 15” can be read as “substrate 10”.

As shown in FIG. 1, the microstructure 161 is a convex structure that goes from the surface on the sealing substrate 15 side in the microstructure layer 16 toward the atmosphere side. The shape of the microstructure 161 is not particularly limited, and can be set as appropriate depending on, for example, the design of the organic EL element 1 and the direction of light emission. Specifically, the shape has, for example, cones such as a cone and a pyramid, a truncated cone, a column such as a cylinder and a prism, a hemisphere, a hemisphere, a semi-ellipsoid, a bell shape, a lenticular shape, and the like. The shape can be raised. As described above, the present invention aims to improve transparency. For this reason, it is preferable that the microstructure 161 has, for example, a shape in which light scattering is further reduced. The shape is, for example, a tapered shape having a diameter that decreases toward the atmosphere, such as the cone, and the hemispherical shape. By making the microstructure 161 have the shape, for example, light incident on the interface at a critical angle or more can be reduced, and total reflection can be suppressed. For this reason, for example, more light can be extracted. The width and height of the microstructure 161 and the interval are not particularly limited. For example, the width and height are, for example, 0.45 to 100 μm, 0.5 to 50 μm, 0.7 to 20 μm, and the interval is, for example, For example, 0 to 100 μm, 0 to 50 μm, and 0 to 20 μm. The shape, size, and interval of the microstructure 161 may have regularity, for example, or may not have regularity, for example, in order to reduce light interference.

The volume ratio of the microstructure 161 in the microstructure layer 16 is preferably 1 to 50%, for example. Specifically, the volume ratio is preferably 50% or less from the viewpoint that it is easy to prevent cracks, cracks and the like from entering due to the strength reduction of the microstructure layer 16. Further, from the viewpoint of suppressing reflection and obtaining light guide to the viewing side, the volume ratio is preferably 1% or more.

The material for forming the microstructure 161 is not particularly limited, and for example, a transparent thermoplastic organic material, a photoresist material, or the like can be used. Specific examples of the material include thiourethane resin, polyphosphonate resin, polymethyl methacrylate (PMMA) resin, phenol (novolak) resin, polyimide resin, epoxy resin, and silicone resin. And a resin having a high refractive index added with a small amount of a high refractive index material such as titanium oxide. When the thermoplastic material is used as a material for forming the microstructure 161, the microstructure 161 can be formed by, for example, a method of imprinting the thermoplastic material with a pressing mold in which a predetermined pattern is repeated, a nanoimprint technique, and the like. When the photoresist material is used, the microstructure 161 can be formed by, for example, photolithography using a photomask having a certain pattern repeated. The material for forming the microstructure 161 is preferably formed of the same material as the sealing substrate 15 on which the microstructure layer 16 is formed, for example. Thereby, since reflection due to a difference in refractive index between the sealing substrate 15 and the microstructure 161 does not occur, the light extraction efficiency can be improved.

Further, the microstructure 161 may be formed, for example, by processing the surface of the sealing substrate 15. Specifically, when the material of the sealing substrate 15 is a transparent flexible film, a thermoplastic resin, or the like, the microstructure 161 can be formed by, for example, the pressing die. When the material of the sealing substrate 15 is glass or the like, the microstructure 161 can be formed by, for example, an etching process, a sand blast process, or the like.

The material for forming the planarization layer 162 is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethers such as polyamide and polyethersulfone, polystyrene (PS), and polyesteramide. , Acrylic resin such as polycarbonate (PC), polyolefin, polymethyl methacrylate (PMMA), transparent resin such as silicone resin, epoxy resin, vinyl / allyl ester (PET) resin, and silicon oxide, aluminum oxide, titanium oxide Inorganic oxides such as, and metal oxides. Only one type of material for forming the planarization layer 162 may be used, or a plurality of types may be used in combination.

In FIG. 1, the microstructure layer 16 is formed on the surface of the sealing substrate 15 opposite to the side on which the organic EL layer 12 is laminated, but is not limited to this. For example, the microstructure layer 16 May be formed on the surface of the sealing substrate 15 on the side where the organic EL layer 12 is laminated. In this case, the microstructure 161 is a convex structure that faces from the surface on the stacking side of the organic EL layer 12 in the microstructure layer 16 to the surface on the sealing substrate 15 side.

In this case, the microstructure layer 16 preferably includes a planarizing layer 162. When the microstructure layer 16 includes the planarization layer 162, for example, the anode-organic layer-cathode film thickness can be made uniform. For this reason, for example, the short circuit of the organic layer can be prevented without concentrating the electric field in a portion where the anode-cathode distance is short in the device.

When the microstructure layer 16 is formed on the surface of the sealing substrate 15 on the side where the organic EL layer 12 is laminated, the organic EL element 1 can be manufactured as follows, for example. That is, for example, first, the planarization layer 162 is formed on the sealing substrate 15. Then, a mold corresponding to the microstructure 161 is formed on the surface of the planarization layer 162 by stamping using a microimprint (nanoimprint) technique. Thereafter, the mold is filled with the material of the microstructure 161. Further, for example, after the planarization layer 162 is formed on the sealing substrate 15 with positive photosensitivity, underexposure and underdevelopment are performed to form a mold corresponding to the microstructure 161. Then, the microstructure layer 16 may be formed by filling the mold with the material of the microstructure 161. The shape of the mold can be arbitrarily designed depending on, for example, the shape of the photomask serving as the bottom.

By forming the microstructure layer 16, for example, the incident angle of light from the substrate side becomes less than the critical angle of total reflection at the interface with the atmosphere, and reflection of light at the interface can be prevented. Further, for example, even when reflection occurs, the reflected light is incident again on another interface in the microstructure, and the light can be extracted to the atmosphere side. Thereby, the multiple reflection in an organic EL element can be suppressed, and coloring of an element can be suppressed and transparency can be improved. Furthermore, by forming the microstructure layer 16, for example, the ratio of light incident on the organic EL element 1 from the outside exceeding the critical angle is reduced, so that reflection on the surface of the organic EL element 1 is suppressed. This can also improve the transparency of the device.

(Embodiment 2)
As shown in FIG. 3, the organic EL element 2 of the present embodiment is the same as the organic EL element 1 of Embodiment 1 except that the light extraction layer includes a refractive index adjustment layer 26 instead of the microstructure layer 16. It is the same.

When the light is transmitted, a critical angle is generated at the interface between the layers included in the organic EL element based on the difference in refractive index between the layers. For example, when the electrode is ITO, the refractive index is about 1.9, when the substrate is glass (soda glass, non-alkali glass, etc.), the refractive index is about 1.5, and the refractive index in the atmosphere is about 1.0. And the difference in refractive index between them is large. Light incident at an incident angle greater than the critical angle is totally reflected at the interface between the layers. According to the present invention, by forming the refractive index adjustment layer 26 at the interface between the layers, the difference in refractive index between the interfaces can be reduced, and reflection at the interface can be suppressed.

As shown in FIG. 3, the refractive index adjustment layer 26 includes a high refractive index layer 261, a medium refractive index layer 262, and a low refractive index layer 263, which are stacked in the above order from the sealing substrate 15 side. Has been. In this embodiment, the sealing substrate 15, the high refractive index layer 261, the medium refractive index layer 262, the low refractive index layer 263, and the atmosphere have a refractive index that decreases in this order. However, the order of the refractive index is not limited to the above-described order as long as the refractive index decreases from the sealing substrate 15 side to the atmosphere side in the refractive index adjustment layer 26. For example, the high refractive index layer 261 The refractive index may be larger than that of the sealing substrate 15, and the low refractive index layer 263 may have a refractive index smaller than that of the atmosphere. For example, when the refractive index of the high refractive index layer 261 is larger than that of the sealing substrate 15, for example, light from the sealing substrate 15 side easily enters the high refractive index layer 261, and the light is adjusted to the refractive index adjustment layer 26. Therefore, it is possible to prevent light from being reflected to the organic EL layer 12 side and absorbing again.

The refractive index adjusting layer 26 is not limited to the three layers, and the refractive index only needs to increase from the sealing substrate 15 side toward the atmosphere side. For example, 1 to 10 layers, 1 to 6 layers, It can be in the range of 1 to 3 layers.

The material for forming the refractive index adjusting layer 26 is not particularly limited. For example, TiO ₂ (refractive index n = 2.40), ZrO ₂ (n = 2.00), Al ₂ O ₃ (n = 1.60), SiO ₂ (n = 1.46), MgF ₂ (n = 1.37), fluororesin (n = 1.33), polysiloxane (n = 1.30), porous silica film (n = 1.16) and the like.

The refractive index adjusting layer 26 is not limited to the layered structure, for example, and may be a layer whose refractive index changes from the sealing substrate 15 side toward the atmosphere side in one layer. Examples of the material of the refractive index adjusting layer 26 include a porous silica film. A porous silica film or the like is porous and can adjust the size (occupancy ratio) of air holes, so that a film (gradient porous film) having a continuous refractive index change can be formed.

In the organic EL element 2 of the present embodiment, for example, in the high refractive index layer 261, the medium refractive index layer 262, and the low refractive index layer 263, the optical film thickness (nd) is set to 1 / 4λ, 1 / 2λ and 1 / 4λ can be set. By setting the film thickness of the refractive index adjustment layer 26 in this way, light interference occurs, so that surface reflection of light incident on the organic EL element 2 from the outside can be suppressed, and the transmittance of the organic EL element 2 is improved. it can.

In FIG. 3, the refractive index adjustment layer 26 is formed on the surface of the sealing substrate 15 on the side opposite to the organic EL layer 12 side, but is not limited thereto. The layer 26 may be formed on the surface of the sealing substrate 15 on the side where the organic EL layer 12 is laminated. In this case, the refractive index adjustment layer 26 has a refractive index that increases from the sealing substrate 15 side to the organic EL layer side.

By forming the refractive index adjusting layer 26, for example, the refractive index difference at the interface with the atmosphere can be reduced, and reflection of light at the interface can be prevented. Thereby, the multiple reflection in an organic EL element can be suppressed, and coloring of an element can be suppressed and transparency can be improved.

(Measurement of transmittance)
The organic EL device of the present invention was produced, and it was confirmed that the transmittance was improved.

The organic EL device has a transparent substrate (anode electrode layer), a hole injection layer, a hole transport layer, a co-deposition layer of a red light emitting material and a green light emitting material, a blue light emitting layer, a hole blocking layer, and an electron transport on a transparent substrate. A layer, an electron injection layer, a cathode electrode layer, a protective film, a sealing substrate, and a refractive index adjusting layer were formed. Each of the layers was formed by physical vapor deposition (PVD). The transparent electrode layer and the cathode electrode layer were formed by a sputtering method. The hole injection layer, the hole transport layer, the hole block layer, the electron transport layer, and the electron injection layer were formed by a vacuum evaporation method using resistance heating. The light emitting layer was formed by doping (co-depositing) each color dopant (guest material) into the host material. The transparent electrode was uniformly formed by a sputtering method, and then a pattern of an anode electrode was formed by using photoetching and photolithography. For patterning the cathode layer, a stencil mask in which holes were formed in the pattern forming portion was used. The protective film was formed using chemical vapor deposition (CVD). The sealing substrate was manufactured using the following materials, and bonded to the protective film using a silicone-based and acrylic-based bonding material (adhesive). The refractive index adjusting layer was formed on the surface of both or one of the substrate and the sealing substrate using a sputtering method. Further, as a comparative example, an organic EL element was produced in the same manner except that the refractive index adjusting layer was not formed.

The material and thickness of each layer were as follows.
Transparent substrate: Alkali-free glass 0.4mm
Anode electrode layer: ITO 150 nm
Hole injection layer: Copper phthalocyanine 15nm
Hole transport layer: α-NPD 45nm
Red green light emitting layer: CBP + Btp ₂ Ir (acac) / CBP + Ir (ppy) ₃ 20 nm
Blue light emitting layer: CBP + FIr (pic) 10 nm
Hole blocking layer: BCP 5nm
Electron transport layer: Alq ₃ 40 nm
Electron injection layer: Mg: Ag 10: 1 10 nm
Cathode electrode layer: ITO 100 nm
Protective film: Silicon oxynitride film SiON 100 nm
Sealing substrate: PET film 100 μm

The refractive index adjusting layer has a laminated structure of layers using TiO ₂ , Al ₂ O ₃ , and MgF ₂ as materials from the transparent substrate and the sealing substrate side. In the laminated structure, the optical film thickness of each layer is set so that the optical film thickness of each layer of TiO ₂ and MgF ₂ is ¼ wavelength with respect to 555 nm, which has the highest human visibility. The optical film thickness of the Al ₂ O ₃ layer was set to be ½ wavelength.

For the organic EL element, the total luminous flux was measured with a spectrophotometer, and the transmittance was calculated. The total luminous flux was measured using an integrating sphere type total luminous flux measuring system manufactured by Labsphere, Inc., and an integrating sphere having a diameter of 1000 mm. The transmittance was measured using an ultraviolet-visible spectrophotometer manufactured by Shimadzu Corporation.

As a result, the transmittance is improved by 21% on average when the refractive index adjusting layer is formed on both surfaces of the organic EL element, compared with the case where the refractive index adjusting layer is not formed, and the average is 26 in the blue region. % Improved. Thus, it was confirmed that by forming the refractive index adjusting layer, the transmittance was improved and coloring of the element was suppressed. Moreover, since the ratio which the said transmittance | permeability improved was higher in a blue area | region, it turned out that the improvement (reduction) effect of yellowishness is acquired by forming the said refractive index adjustment layer.

When the refractive index adjusting layer was formed only on one side of the organic EL element, the ratio of the improved transmittance was about 50% when both were formed on both sides. The transmittance is about 1 to 3% when the refractive index adjusting layer is provided on the surface of the sealing substrate on the cathode side, compared with the case where it is provided on the surface of the transparent substrate on the anode side. It was big. This is because, on the cathode side, reflection is suppressed by performing bonding with the bonding material between the sealing substrate and the cathode electrode. This is probably because the contribution of reflection at the interface between the stop substrate and the atmosphere increases. However, this is a guess, and the present invention is not limited to the guess.

The total luminous flux is improved by an average of 28% when the refractive index adjustment layer is formed on both surfaces of the organic EL element, compared with the case where the refractive index adjustment layer is not formed, and by an average of 31% in the blue region. . Thus, it was confirmed that the total luminous flux was improved by forming the refractive index adjustment layer. The effect tended to be higher in the blue region. From this, it is shown that the formation of the refractive index adjustment layer suppresses repeated light absorption inside the organic EL element and contributes to improvement of light extraction efficiency and color improvement during light emission. It was done.

(Embodiment 3)
The organic EL element 1 of this embodiment is the same as the organic EL element 1 of Embodiment 1 except that the size of the microstructure 161 is small.

In this embodiment, the width, height, and interval of the microstructure 161 are, for example, not more than the vicinity of the visible light wavelength range. Moreover, the space | interval of the minute structure 161 is a magnitude | size which is a grade which does not generate | occur | produce a diffracted wave, for example. Specifically, for example, the width and height are, for example, 100 to 700 nm, 150 to 500 nm, and 200 to 450 nm, respectively, and the spacing is, for example, 0 to 500 nm, 0 to 400 nm, and 0 to 300 nm. It is. Here, in the microstructure layer 16, as it approaches the sealing substrate 15 side in the thickness direction, almost all of the microstructure layer 16 is configured by the microstructure 161, and the area occupied by the atmosphere becomes very small. On the other hand, the area occupied by the microstructure 161 becomes very small as it approaches the atmosphere side. When the width and height of the microstructure 161 and the interval are set to the above values, for example, the interaction between light and the microstructure 161 is reduced. For this reason, as the proportion of the microstructure 161 in the microstructure layer 16 changes from the sealing substrate 15 side to the atmosphere side, the apparent refractive index of the microstructure layer 16 also changes from the refractive index of the microstructure 161. The refractive index of the planarizing layer 162 changes.

In the present embodiment, it is preferable that the microstructure layer 16 does not include the planarization layer 162. In this case, the apparent refractive index of the microstructure layer 16 changes from the refractive index of the microstructure 161 as the proportion of the microstructure 161 in the microstructure layer 16 changes from the sealing substrate 15 side to the atmosphere side. It changes to the refractive index of the atmosphere.

Also by the organic EL element 1 of the present embodiment, the same effect as that of the second embodiment can be obtained by the apparent change of the refractive index. This embodiment is suitable, for example, when the organic EL element 1 is a small light emitting element that requires fine expression.

(Embodiment 4)
The organic EL lighting device of the present invention includes the organic EL element of the present invention. According to the organic EL lighting device of the present invention, coloring can be suppressed and transparency can be improved.

The organic EL element of the present invention can be used for, for example, a vehicle lamp. Specifically, a lamp that emits light in three dimensions can be formed by stacking a plurality of the organic EL elements of the present invention. In this case, for example, only in the organic EL element at the end of the plurality of organic EL elements, the substrate on one side or the like is formed in a mirror shape instead of being transparent. Can be obtained.

(Embodiment 5)
The light extraction film of the organic EL device of the present invention is a coloring suppression film, and includes at least one of the microstructure layer and the refractive index adjustment layer.

The film can be formed of, for example, the material of the microstructure layer and the refractive index adjustment layer. The configurations of the microstructure layer and the refractive index adjustment layer are as described above, for example.

In the film of this embodiment, for example, an adhesive layer for bonding to a substrate may be further provided on the microstructure layer and the refractive index adjustment layer. As a material of the adhesive layer, for example, as described in the second embodiment, by using a material that takes into consideration a difference in refractive index between the substrate and the light extraction film, at the interface between the substrate and the light extraction film. Reflection can be suppressed. Examples of the material for the adhesive layer include silicone-based materials and acrylic-based materials. Thereby, in the interface of a board | substrate and the film for light extraction, reflection can be suppressed more and light can be extracted more.

According to the film of the present invention, in an organic EL element, coloring can be suppressed and transparency can be improved.

As mentioned above, although this invention was demonstrated with reference to embodiment, this invention is not limited to the said embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority based on Japanese Patent Application No. 2018-059209 filed on March 26, 2018, the entire disclosure of which is incorporated herein.

According to the present invention, coloring in the organic EL element can be suppressed and transparency can be improved. Therefore, for example, according to the present invention, for example, an organic EL element with high designability can be provided. Moreover, since the light extraction efficiency is improved by suppressing multiple reflections, external quantum efficiency, power efficiency, and the like can be improved.

A part or all of the above embodiment can be described as in the following supplementary notes, but is not limited to the following.
(Appendix 1)
Including a first substrate, an anode, an organic EL layer, a cathode, a second substrate, and a light extraction layer;
The first substrate, the anode, the organic EL layer, the cathode, and the second substrate are laminated in this order,
The organic EL layer includes a light emitting layer,
The light extraction layer includes at least one of the first substrate and the second substrate, the surface on which the anode, the organic EL layer, and the cathode are stacked, or the anode, the organic EL layer, And an organic EL device, wherein the organic EL device is disposed on at least one of surfaces opposite to the side on which the cathode is laminated.
(Appendix 2)
The organic EL element according to appendix 1, wherein the anode and the cathode are transparent electrodes.
(Appendix 3)
The organic EL element according to appendix 1 or 2, wherein the light extraction layer is at least one of a microstructure layer and a refractive index adjustment layer.
(Appendix 4)
The organic EL element according to appendix 3, wherein the microstructure in the microstructure layer has a convex shape toward the atmosphere.
(Appendix 5)
The organic EL element according to appendix 3 or 4, wherein the microstructure in the microstructure layer has a shape having a protrusion toward the opposite side of the substrate on which the microstructure layer is disposed.
(Appendix 6)
The organic EL element according to any one of appendices 3 to 5, wherein a height and a width of the microstructure in the microstructure layer are not more than a wavelength range of visible light.
(Appendix 7)
The organic EL according to any one of appendices 3 to 6, wherein the refractive index adjustment layer is a layer whose refractive index decreases toward the side opposite to the side on which the anode, the organic EL layer, and the cathode are laminated. element.
(Appendix 8)
The refractive index adjustment layer is a laminated structure including a plurality of layers,
The organic EL element according to any one of appendices 3 to 7, wherein the plurality of layers have a refractive index that decreases toward a side opposite to a side where the anode, the organic EL layer, and the cathode are stacked.
(Appendix 9)
An organic EL lighting device comprising the organic EL element according to any one of appendices 1 to 8.
(Appendix 10)
A light extraction film for suppressing coloration of an organic EL device, comprising at least one of a microstructure layer or a refractive index adjustment layer.
(Appendix 11)
The film is a film disposed on the substrate of the organic EL element,
The film according to appendix 10, wherein the microstructure in the microstructure layer is convex toward the opposite side of the substrate in a state where the film is disposed on the substrate.
(Appendix 12)
The film is a film disposed on the substrate of the organic EL element,
The film according to appendix 10, wherein the refractive index adjusting layer is a layer having a refractive index that decreases toward the opposite side of the substrate.

DESCRIPTION OF SYMBOLS 1, 2 Organic EL element 10 Substrate 11 Anode 12 Organic EL layer 121 Hole injection layer 122 Hole transport layer 123 Light emitting layer 124 Electron transport layer 125 Electron injection layer 13 Cathode 14 Sealing layer 15 Sealing substrate 16 Microstructure layer 26 Refractive index adjustment layer

Claims (10)

Including a first substrate, an anode, an organic EL layer, a cathode, a second substrate, and a light extraction layer;
The first substrate, the anode, the organic EL layer, the cathode, and the second substrate are laminated in this order,
The organic EL layer includes a light emitting layer,
The light extraction layer includes at least one of the first substrate and the second substrate, the surface on which the anode, the organic EL layer, and the cathode are stacked, or the anode, the organic EL layer, And an organic EL device, wherein the organic EL device is disposed on at least one of surfaces opposite to the side on which the cathode is laminated. The organic EL element according to claim 1, wherein the anode and the cathode are transparent electrodes. The organic EL element according to claim 1, wherein the light extraction layer is at least one of a microstructure layer and a refractive index adjustment layer. The organic EL element according to claim 3, wherein the microstructure in the microstructure layer is convex toward the atmosphere side. 5. The organic EL element according to claim 3, wherein the microstructure in the microstructure layer has a shape having a protrusion toward the opposite side of the substrate on which the microstructure layer is disposed. The organic EL element according to any one of claims 3 to 5, wherein a height and a width of the microstructure in the microstructure layer are not more than a wavelength range of visible light. The refractive index adjustment layer is a layer according to any one of claims 3 to 6, wherein the refractive index decreases toward the side opposite to the side on which the anode, the organic EL layer, and the cathode are stacked. Organic EL element. The refractive index adjustment layer is a laminated structure including a plurality of layers,
The organic EL element according to any one of claims 3 to 7, wherein the plurality of layers have a refractive index that decreases toward a side opposite to a side on which the anode, the organic EL layer, and the cathode are stacked. . An organic EL lighting device comprising the organic EL element according to claim 1. A light extraction film for suppressing coloration of an organic EL device, comprising at least one of a microstructure layer or a refractive index adjustment layer.

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