JP2019106245A - Organic EL element and organic EL lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element capable of suppressing light emission from a non-light emitting surface side. An organic EL element of the present invention includes a substrate, a first electrode, an organic EL layer, and a second electrode, and the organic EL layer includes a light emitting layer, and the substrate and the above. The first electrode, the organic EL layer, and the second electrode are laminated in this order, and one of the first electrode and the second electrode is an anode and the other is a cathode. Yes, the first electrode is a transparent electrode, and the second electrode is arranged at intervals in the plane direction of the organic EL layer, and is an interface between the light emitting layer and the organic EL element. Of these, the optical distance between the light emitting layer and the interface on the first electrode side is L1, and the optical distance between the light emitting layer and the interface on the second electrode facing the organic EL layer is L2. , The L1 and the L2 have a predetermined relationship. [Selection diagram] Fig. 1

Description

  The present invention relates to an organic EL element and an organic EL lighting device.

  An organic EL element that emits light in a slit shape is known as an organic EL element having high designability (Patent Document 1). The organic EL element that emits light in the form of a slit can be formed, for example, by forming a metal electrode in the form of a slit and arranging only an organic film without disposing the electrode between the slit and the slit. Thereby, the space between the slits becomes transparent, and when light is not emitted, the opposite side (back side) of the element can be seen through the space between the slits. Then, at the time of light emission, the slit portion emits light, and due to the spread of light, the light emitting surface side appears to be entirely glowing.

JP, 2016-177967, A

  On the other hand, in the organic EL element that emits light in the form of a slit, for example, even when the organic EL element emits light, no electrode is disposed between the slits, so it appears that it hardly emits light It is considered. However, in practice, for example, light reflected inside the organic EL element causes light leakage through the slits, which causes the non-light emitting surface side to look shiny, so the design of the organic EL element The present inventor has found that there is a problem such as loss of

  Then, this invention aims at suppressing the light emission from the said non-light-emission surface side, for example in the organic EL element which light-emits in slit shape.

In order to achieve the above object, the organic EL device of the present invention is
A substrate, a first electrode, an organic EL layer, and a second electrode,
The organic EL layer includes a light emitting layer,
The substrate, the first electrode, the organic EL layer, and the second electrode are stacked in this order,
One of the first electrode and the second electrode is an anode, and the other is a cathode.
The first electrode is a transparent electrode,
The second electrodes are spaced apart in the surface direction of the organic EL layer,
The optical distance between the light emitting layer and the interface on the side closer to the first electrode than the light emitting layer among the interfaces in the organic EL element is L1, the light emitting layer, and the organic EL layer in the second electrode When an optical distance from the interface on the facing side is L2, a relationship between the L1 and the L2 is that the interference of at least two lights selected from the group consisting of the following (I) to (III) is caused by interference: It is characterized in that it is a relationship which becomes light of a matching phase.
(I) Light emitted from the light emitting layer, light reflected at the interface closer to the first electrode than the light emitting layer in the interface of the organic EL element (II) emitted from the light emitting layer, the second electrode Light reflected by the interface facing the organic EL layer in the above, and light reflected by the interface closer to the first electrode than the light emitting layer (III) emitted from the light emitting layer, and the second electrode Light emitted in the direction

  According to the present invention, for example, in an organic EL element which emits light in a slit shape, light emission from the non-light emitting surface side can be suppressed.

FIG. 1 is a schematic view (cross-sectional view) of the organic EL element in Embodiment 1 viewed from the side. FIG. 2 is a schematic view (cross-sectional view) of the organic EL element in Embodiment 1 viewed 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. FIG. 4 is a schematic view (cross-sectional view) of the organic EL element in Embodiment 3 as viewed from the side.

In the organic EL element of the present invention, for example, when the wavelength of light emitted from the light emitting layer is λ, the relationship between L 1, L 2 and λ is as shown in the following formula (7), and 5) At least one of the relationships shown in at least one of (6) is satisfied.

In the organic EL element of the present invention, for example, when the wavelength of light emitted from the light emitting layer is λ, the relationship between L 1, L 2 and λ is represented by the following formulas (1) and (2), At least one relationship in the group consisting of the relationships shown in the following formulas (3) and (4) and the relationships shown in the following formulas (5) and (6) is satisfied.

  In the organic EL element of the present invention, for example, among the interfaces in the organic EL element, the interface on the first electrode side with respect to the light emitting layer is the side of the first electrode facing the organic EL layer; Is the opposite surface.

  In the organic EL element of the present invention, for example, among the interfaces in the organic EL element, the interface on the side closer to the first electrode than the light emitting layer is opposite to the side on the substrate facing the first electrode It is an interface on the side.

  In the organic EL element of the present invention, for example, the second electrode is arranged in a slit shape.

  The organic EL element of the present invention further includes, for example, a phase adjustment layer.

  In the organic EL element of the present invention, for example, the phase adjustment layer is disposed between the substrate and the first electrode.

  In the organic EL element of the present invention, for example, when the wavelength of the light emitted from the light emitting layer is λ, the phase adjustment layer has a thickness of (1/4) λ + (1/2) pλ.

  In the organic EL element of the present invention, for example, the phase adjustment layer is disposed to correspond to every other gap in the second electrode.

  In the organic EL element of the present invention, for example, the second electrode is a metal electrode.

  Next, an embodiment of the present invention will be described using the drawings. The present invention is not limited or limited at all by the following embodiments. In the following drawings, the same parts are denoted by the same reference numerals. The description in each embodiment can use each other. Furthermore, the configurations of the respective embodiments can be combined unless otherwise stated. Further, in the drawings, for convenience of explanation, the structure of each part may be appropriately simplified and shown, and the dimensional ratio of each part may be schematically shown differently from the actual one.

(Embodiment 1)
FIG. 1 is a schematic view (cross-sectional view) of the organic EL element 1 in the present embodiment as viewed from the side. The organic EL element 1 of the present embodiment is a bottom emission type organic EL element, and in FIG. 1, the downward direction is the original light emission direction (light emitting surface side) of the organic EL element 1, and the upward direction is originally In the non-emitting direction (non-emitting side). As shown in FIG. 1, the organic EL device 1 according to the present embodiment includes a substrate 10, an anode 11, an organic EL layer 12, a cathode 13, an intermediate layer 14, and a sealing substrate 15. The anode 11, the organic EL layer 12, and the cathode 13 are stacked in the above order on the top. The sealing substrate 15 is disposed to face the substrate 10 with the intermediate layer 14 interposed therebetween. 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, and these are stacked in the above order. The cathodes 13 are arranged in the form of slits at intervals as described later. The intermediate layer 14, the sealing substrate 15, the hole injection layer 121, the hole transport layer 122, the electron transport layer 124, and the electron injection layer 125 are not essential components and are included in the organic EL element 1. It may or may not be included. Moreover, in the organic EL element 1, the anode 11 and the cathode 13 may be laminated in the reverse order. In this case, the anodes 11 are arranged in the form of slits at intervals.

  In the organic EL device 1, the substrate 10, the anode 11, the hole injection layer 121, the hole transport layer 122, the light emitting layer 123, the electron transport layer 124, the electron injection layer 125, the cathode 13, the intermediate layer 14 and the sealing substrate 15. The material is not particularly limited, and known materials can be used.

  The substrate 10 is preferably a substrate having a high transmittance to transmit the light emitted from the light emitting layer 123 in the organic EL element 1. As a forming material of the substrate 10, for example, glass such as non-alkali glass, soda glass, soda lime glass, borosilicate glass, aluminosilicate glass, quartz glass, etc .; polyester such as polyethylene naphthalate, polyethylene terephthalate; polyimide; polymethacrylic acid Acrylic resins such as methyl ethyl, poly ethyl methacrylate, poly methyl acrylate and poly ethyl acrylate; polyether sulfone; polycarbonate ester; and the like. The size (length and width) of the substrate 10 is not particularly limited, and may be set appropriately according to, for example, the desired size of the organic EL element 1. The thickness of the substrate 10 is also not particularly limited, and can be appropriately set according to the forming material, the use environment, and the like, and is, for example, 1 mm or less.

  In the present embodiment, the anode 11 is a transparent electrode. As a material which forms the said transparent electrode, an indium tin oxide (ITO) etc. are mention | raise | lifted, for example.

The light emitting layer 123 is a layer that recombines electrons and holes injected from the electrode and emits fluorescence, phosphorescence, and the like. The light emitting layer 123 contains a light emitting material. The light emitting material is, for example, tris (8-quinolinol) aluminum complex (Alq ₃ ), bisdiphenylvinylbiphenyl (BDPVBi), 1,3-bis (p-t-butylphenyl-1,3,4-oxadiazole ) 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 weight compounds such as-(4-methylstyryl) phenylamino) naphthalene, and high molecular compounds such as polyphenylene vinylene polymers.

The light emitting material may be, for example, a binary system of a host and a dopant, and a material in which energy of an excited state generated in a host molecule is transferred to the dopant molecule and the dopant molecule emits light. Such a light emitting material is specifically, for example, a quinolinol metal complex such as host Alq ₃ and a dopant 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran ( DCM), quinacridone derivatives such as 2,3-quinacridone, or coumarin derivatives such as 3- (2'-benzothiazole) -7-diethylamino coumarin, or bis (2-) which is an electron transport material of a host Methyl-8-hydroxyquinoline) -4-phenylphenol-aluminum complex doped with condensed polycyclic aromatic such as perylene as a dopant, or 4,4′-bis (hole transporting layer material of host) m-Tolylphenylamino) biphenyl (TPD) doped with a dopant such as rubrene, a host 4,4 ' Platinum complexes of tris- (2 ferrinyl pyridine) as a dopant for carbazole compounds such as -biscarbazolylbiphenyl (CBP) and 4,4'-bis (9-carbazolyl) -2,2'-dimethylbiphenyl (CDBP) ) Iridium complexes (Ir (ppy) ₃ ), (bis (4,6-di-fluorophenyl) -pyridinate-N, C2 ′) picolinate iridium complexes (FIr (pic)), (bis (2- (2 ′ -Benzo (4,5-α) thienyl) pyridinate-N, C2 ') (acetylacetonate) iridium complex (Btp ₂ Ir (acac)), Ir (pic) ₃ , Bt ₂ Ir (acac), etc. The light emitting material may be appropriately selected according to the target light emission color of the organic EL element 1, for example.

  As a material for forming the hole injection layer 121, for example, arylamine derivatives such as copper phthalocyanine (Cu-Pc), m-MTDATA, 2-TNATA, and star burst type aromatic amines such as TCTA, spiro-TAD, 2,3,6,7,10,11-Hexacyano-1,4,5,8,9,12-Hexaaza triphenylene (HAT-CN), and vanadium pentoxide and trioxide for hole injecting organic materials Chemical doping of molybdenum etc. is mentioned. As a material for forming the hole transport layer 122, for example, 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, triphenylamine Furthermore, TPTR, TPTE, NTPA, a starburst type aromatic amine etc. which were multimerized are mention | raise | lifted. As a material for forming the electron transport layer 124, for example, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole (Bu-PBD), 2, 9 -Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 1,3-bis (p-t-butylphenyl-1,3,4-oxadiazolyl) phenyl (OXD-7), etc. Oxadiazole derivatives, triazole derivatives, quinolinol metal complexes, triphenyldiamine derivatives and the like can be mentioned. Examples of the material for forming the electron injection layer 125 include alkali metals such as lithium and cesium, fluorides and oxides of alkaline earth metals such as calcium, magnesium silver, lithium aluminum alloy, and the like.

  The cathode 13 is, for example, a counter electrode of metal (eg, aluminum etc.). The cathodes 13 are spaced apart in the form of slits. The width of the cathode 13 and the width of the gap (the length in the direction perpendicular to the length direction of the cathode 13 and the slit in the surface direction of the organic EL layer 12) are not particularly limited, and the width of the cathode 13 is For example, it is 0.1 to 5000 μm, 100 to 3000 μm, and 200 to 2000 μm, and the width of the gap is 2 to 10000 μm, 200 to 6000 μm, and 400 to 4000 μm.

  In the present embodiment, the cathodes 13 are in the form of slits and are spaced apart. However, the shape of the cathode 13 is not limited to the slit shape, and may be arranged at intervals, for example, may be a grit shape. In the cathodes 13, for example, the cathodes 13 spaced apart may be partially connected to each other or not connected.

  The intermediate layer 14 is, for example, a layer formed by at least one of the group consisting of a protective layer, a filler layer, and an adhesive layer.

The protective layer is a layer that protects the organic EL element 1. The protective layer preferably has gas barrier properties, for example, in order to prevent entry 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 ) and the like. The protective layer may be, for example, a layer consisting of a single layer or a layer consisting of a plurality of layers. In the latter case, for example, in order to enhance the gas barrier properties, a plurality of the films having the gas barrier properties can be laminated.

  When it is set as the organic EL element 1 which has flexibility, in order to give flexibility to the said protective layer, you may further laminate | stack a buffer layer on the said protective layer. The material for forming the buffer layer is, for example, an epoxy resin, a silicone resin, an acrylic resin, an imide resin, an amide resin, a urethane resin, from the viewpoints of permeability, flexibility, and thermal stability. And inorganic resins such as an olefin-based resin, an organic-inorganic hybrid material obtained by adding silica or the like of an inorganic material to the resin material, and a coating type silicon oxide film. The protective layer and the buffer layer may be alternately stacked, for example.

  The filler layer is, for example, a layer containing a filler such as gas and resin. The gases are, for example, inert gases such as nitrogen, argon and neon, and noble gases. The resin is, for example, an epoxy resin, a silicone resin, an acrylic resin, an imide resin, an amide resin, a urethane resin and an olefin resin.

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

  The intermediate layer 14 may be, for example, a layer composed of any one kind of the protective layer, the filling layer, and the adhesive layer, or may be a layer of a laminated structure in which any two or more kinds are combined. When the intermediate layer 14 is the laminated structure including, for example, three layers of the protective layer, the filler layer, and the adhesive layer, the lamination order of the layers is not particularly limited. For example, the protective layer, the filler It is possible to laminate in the order of the layer and the adhesive layer. For example, the protective layer is preferably disposed in a region in contact with the anode 11, the organic EL layer 12, the organic layer of the cathode 13, and the like. When the protective layer is disposed, the filler layer may or may not be disposed. In addition, for example, the protective layer may not be disposed in a region in contact with the organic layer or the like, and the filling layer may be disposed. The form in which the protective layer is not disposed and the filling layer is disposed is used, for example, in the field of lighting. The adhesive layer is disposed, for example, on the protective layer or the filler layer (a region in contact with the protective layer or the filler layer and opposite to a region in contact with the organic layer or the like).

  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 non-alkali glass and soda glass, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PES (polyether sulfone), PI (polyimide) And COP (cycloolefin polymer), films, sheets, resin substrates and the like.

According to the present embodiment, even when the cathode 13 has the gap, for example, light of at least one of (I) to (III) below can be prevented from passing through the gap of the cathode 13.
(I) Light emitted from the light emitting layer and reflected at the interface closer to the anode than the light emitting layer among the interfaces of the organic EL element (II) emitted from the light emitting layer and reflected at the interface of the cathode facing the organic EL layer Further, light reflected at the interface closer to the anode than the light emitting layer (III) light emitted from the light emitting layer and emitted in the direction of the cathode

  In the above (I), among the interfaces in the organic EL element, the interface closer to the anode than the light emitting layer is, for example, the interface between the anode 11 and the substrate 10 in FIG. 1 and the interface between the substrate 10 and the air. In the following description, the interface on the anode side of the light emitting layer among the interfaces in the organic EL element will be described as, for example, the interface between the anode 11 and the substrate 10 in FIG. The same applies to the case where the interface is, for example, the interface between the substrate 10 and the air in FIG. 1 without limitation.

  In the present invention, to suppress the light emission from the non-light emitting surface side may weaken all the light among the lights of (I) to (III) or weaken some light, for example. Good. In the latter case, for example, the light of (I) and (II) may be attenuated. In the structure of a general organic EL element, since the distance between the light emitting layer and the cathode is as short as, for example, several tens of nm, the influence of the light of (III) is unlikely to be a problem. Therefore, for example, the light emission from the non-light emitting surface side can be suppressed also by weakening the lights of (I) and (II).

  In the case of reflection at the interface of the cathode 13 on the side facing the organic EL layer 12, for example, a shift of 1/2 × λ occurs in the phase of the light. On the other hand, in the case of reflection at the interface between the anode 11 and the substrate 10, for example, since the refractive index of the anode 11 is larger than that of the substrate 10, the phase of the light does not deviate.

In the present embodiment, the optical distance between the light emitting layer 123 and the interface between the anode 11 and the substrate 10 is L1, the optical distance between the light emitting layer and the interface between the organic EL layer 12 and the cathode 13 is L2, and the light emitting layer When the wavelength of the light emitted from 123 is λ, the L1, L2, and λ satisfy the relationship of the following formula (7).

  In the above formula (7), a is an arbitrary integer of 0 or more, and is not particularly limited. a can be appropriately set according to, for example, a desired multilayer film structure of the organic EL element 1 and the like. For example, each a may be the same or different. (Same below)

  The optical distance can be determined, for example, by multiplying the actual distance by the refractive index. The optical distances L1 and L2 can be obtained, for example, by obtaining the optical distances of the films included in the L1 and L2 and adding the optical distances.

  In the case where the actual distance is determined based on the optical distances L1 and L2 in the organic EL element 1, the actual distance may actually have an error within an allowable range with respect to the value determined by the calculation, For example, the light may be in a range in which the light can be weakened by interference.

  In order to satisfy the relationship of the formula (7), for example, L1 and L2 can be adjusted by changing the film thickness of at least one of the hole injection layer 121, the hole transport layer 122, and the anode 11. As described above, in order to satisfy the relationship of the formula (7), changing the film thickness of each layer on the hole side of the organic EL element 1 has, for example, a small influence on the light emission / electric characteristics of the element. ,preferable. Specifically, the change of the film thickness is, for example, based on an emission spectrum affected by optical interference, an external quantum efficiency, etc., to obtain L1 that is optimum, and then, the film thickness of each layer constituting L1 Adjust the balance. The balance of the film thickness of each layer is not particularly limited, and, for example, the carrier balance between holes and electrons injected into the device and the light emission efficiency by it, based on the mobility and the injection efficiency of the material forming each layer. The quantum efficiency can be set appropriately so as to obtain a desired value. Thereby, for example, light leakage to the back surface can be suppressed, and an organic EL element having a low driving voltage and high luminous efficiency can be obtained. However, the present invention is not limited thereto. For example, L1 and L2 may be adjusted by changing the film thickness of each layer on the cathode 13 side of the organic EL element 1.

  When L1, L2, and λ satisfy the relationship of equation (7), for example, the phases of the light of (I) and (II) are adjusted, respectively, and the light of (I) and the light of (I) The light of II) can be, for example, in antiphase. The lights of (I) and (II) pass through the gap of the cathode 13 and are emitted as leaked light in the non-emission direction of the organic EL element. However, in the organic EL element 1 of the present embodiment, when the L1, the L2, and λ satisfy the relationship of the formula (7), the light of (I) and (II) has, for example, an antiphase. Therefore, these lights weaken by interference. For this reason, the leak of light as shown by the arrow in FIG. 1 can be suppressed. Thus, since the lights of (I) and (II) weaken each other by satisfying the relation of the formula (7), the formula (7) can be obtained, for example, from the non-light emitting surface side of the organic EL element The light emission of the present invention can be suitably applied when the reflection at the interface between the cathode 13 and the organic EL layer 12 and the reflection at the interface between the anode 11 and the substrate 10 have a large contribution. In addition, since the refractive index difference in the interface of the cathode 13 and the organic EL layer 12, and the interface of the anode 11 and the board | substrate 10 is large, for example, it is thought that the contribution by the said reflection is large.

  The light of (II) weakens due to interference with the light of (I), for example, after reflection at the cathode 13. However, the present invention is not limited to this, and the light of (II) is, for example, reflected by the interface of the substrate 10 and the anode 11 after being reflected by the cathode 13, and this light is the light of the light of (I). Interference may be counteracted.

  By satisfying L1, L2, and λ, the two lights can have, for example, opposite phases, but the present invention is not limited to this, and the light is caused by interference. It would be nice if we could weak each other. The phase difference of the light may be in the range of, for example, 135 to 225 degrees, 140 to 220 degrees, and 160 to 200 degrees to be able to weaken by interference.

The L 1, the L 2, and λ may satisfy, for example, the relationship of the following formulas (1) and (2).

  In the formulas (1) and (2), m and n are any integer of 0 or more, and are not particularly limited. m and n can be appropriately set according to, for example, a desired multilayer film structure of the organic EL element 1 and the like. For example, m and n may be the same or different. (Same below)

  When L1, L2, and λ satisfy the relationship of the expressions (1) and (2), for example, the phases of the light of (I) and (II) are adjusted, respectively, and The light and the light of (II) can be, for example, in antiphase. Moreover, the light of (I) and the light of (III) can be, for example, in antiphase. The light of (I) to (III) passes through the gap of the cathode 13 and is emitted as leaked light in the non-emission direction of the organic EL element. However, in the organic EL element 1 of the present embodiment, when the L1, the L2, and λ satisfy the relationship of the formulas (1) and (2), the light of the (I) and (II) and the As the lights of (II) and (III) are, for example, in antiphase, these lights are destructive due to interference. For this reason, the leak of light as shown by the arrow in FIG. 1 can be suppressed. Thus, by satisfying the relationship between the formulas (1) and (2), the lights of the (I) and (II) and the lights of the (II) and (III) weaken each other. 1) and 2), for example, in light emission from the non-light emitting surface side of the organic EL element, reflection at the interface between the cathode 13 and the organic EL layer 12 and reflection at the interface between the anode 11 and the substrate 10 It can be suitably applied when the contribution of is large.

The L1, the L2, and λ may satisfy, for example, the relationship of the following formulas (1 ′) and (2). By satisfying the relationship of the following formulas (1 ′) and (2), for example, the film thickness on the hole injection / hole transport side can be made to have a sufficient size. Therefore, it is preferable from the viewpoint of the reliability of the device.

Alternatively, L1, L2 and λ satisfy the relationship of the following formulas (3) and (4).

  When L1, L2, and λ satisfy the relationship of Equations (3) and (4), for example, the phases of the light of (I) and (II) are respectively adjusted, and The light and the light of (II) can be, for example, in antiphase. Moreover, the light of (II) and the light of (III) can be, for example, in antiphase. The light of (I) to (III) passes through the gap of the cathode 13 and is emitted as leaked light in the non-emission direction of the organic EL element. However, in the organic EL element 1 of the present embodiment, when the L1, the L2 and λ satisfy the relationship of the formulas (3) and (4), the light of the (I) and (II) and the As the lights of (II) and (III) are, for example, in antiphase, these lights are destructive due to interference. For this reason, the leak of light as shown by the arrow in FIG. 1 can be suppressed. Thus, by satisfying the relationship between the formulas (3) and (4), the lights of the (I) and (II) and the lights of the (II) and (III) weaken each other. 3) and (4) show, for example, reflection at the interface between the cathode 13 and the organic EL layer 12 and reflection at the interface between the anode 11 and the substrate 10 in light emission from the non-light emitting surface side of the organic EL element It can be suitably applied when the contribution of is large.

Or said L1, said L2, and (lambda) satisfy | fill the relationship of at least one of following formula (5) and (6).

  When L1, L2, and λ satisfy the relationship of at least one of the formulas (5) and (6), the phases of the light of at least one of the (I) and (II) are respectively adjusted, The light of (I), the light of at least one of (II), and the light of (III) can be, for example, in antiphase. The light of (I) to (III) passes through the gap of the cathode 13 and is emitted as leaked light in the non-emission direction of the organic EL element. However, the organic EL device 1 of the present embodiment is characterized in that the light of (I) and (III) is satisfied when the L1, the L2 and λ satisfy at least one of the expressions (5) and (6). And at least one of the lights of (II) and (III), for example, in antiphase, so that the lights weaken due to interference. For this reason, the leak of light as shown by the arrow in FIG. 1 can be suppressed. Thus, by satisfying the relationship of at least one of the formulas (5) and (6), at least one of the light of (I) and (III) and the light of (II) and (III) is weakened. Since the above equations (5) and (6) are satisfied, for example, when light emitted from the light emitting layer 123 and emitted in the direction of the cathode 13 has a large contribution in light emission from the non-light emitting surface side of the organic EL element. It can apply suitably.

  Alternatively, the L1, the L2, and the λ satisfy the relationship of the formulas (5) and (6).

  The phases of the light of (I) and (II) are respectively adjusted by satisfying the relationship of the equations (5) and (6) with the L1, L2, and λ, and the light of the (I) and the light of the (I) are adjusted. The light of (II) and the light of (III) can be, for example, in antiphase. In addition, when the L1, the L2, and the λ satisfy the relationship of the equations (5) and (6), the phases of the light of the (I) and (II) are adjusted respectively, and the (I) The light and the light of (II) have, for example, the same phase. The light of (I) to (III) passes through the gap of the cathode 13 and is emitted as leaked light in the non-emission direction of the organic EL element. However, in the organic EL device 1 of the present embodiment, the light of (I) and (II) and the light of the above can be obtained by satisfying the relationship of the expressions (5) and (6) with the L1, L2 and λ. As the lights of (II) and (III) are, for example, in antiphase, these lights are destructive due to interference. For this reason, the leak of light as shown by the arrow in FIG. 1 can be suppressed. Thus, by satisfying the relationship between the formulas (5) and (6), the lights of the (I) and (III) and the lights of the (II) and (III) weaken each other. 5) and (6) can be suitably applied, for example, when light emitted from the light emitting layer 123 and emitted in the direction of the cathode 13 has a large contribution in light emission from the non-light emitting surface side of the organic EL element.

  In the organic EL element 1, in the lower portion (hereinafter also referred to as the lower portion of the gap) of the cathode 13, for example, as shown in FIG. It is also called a layer etc.). The organic EL element of the present embodiment is not limited to this. An example of another form is shown in FIG. FIG. 2 is a view showing the organic EL element 1 in which the organic layer and the like are not disposed in the lower part of the gap of the cathode 13. As shown in FIG. 2, in the organic EL element 1, the organic layer or the like may not be disposed or may be partially disposed in the lower portion of the gap, or one of the organic layers or the like may be disposed. Layers of parts may be disposed in whole or in part. When the organic layer or the like is not disposed in the lower portion of the gap, the lower portion of the gap is preferably formed of, for example, the same layer as the intermediate layer 14 described later. When the organic layer or the like is not disposed in the lower part of the gap, for example, when the light is not emitted, it is difficult to cause coloration due to light absorption in the organic layer or the like, so the gap becomes more transparent. For this reason, it is preferable when looking at the opposite side (back side) of the organic EL element 1 through the space between the slits (the gap).

  When the organic layer or the like is not disposed in the lower portion of the gap of the cathode 13, the anode 11 may be formed as a solid film (formed on one side) or may be patterned as shown in FIG. 2. Good. The pattern formation may or may not correspond to, for example, the shape of the gap in the cathode 13. The pattern is, for example, slit-like and grit-like. The pattern formation of the anode 11 can suppress, for example, the reflection of light at the interface between the anode 11 and the substrate 10. For example, in the portion where the anode 11 is not disposed, the light reflection at the interface between the substrate 10 and the intermediate layer 14 is smaller than the light reflection at the interface between the anode 11 and the transparent substrate 10, More light can be emitted in the direction of the original light. Moreover, when the anode 11 is formed on the one side, for example, a dedicated etching process is not necessary, and the process load can be reduced.

  When a part of the organic layer or the like is disposed in the lower portion of the gap, for example, the anode 11 is not disposed in the lower portion of the gap, and only the organic EL layer 12 is disposed. Good. By arranging the organic EL layer 12, for example, the organic EL layer 12 plays a role of an insulating film. Therefore, for the organic EL element 1, for example, short circuit prevention, dark spot suppression and the like can be further performed, whereby the reliability of the organic EL element 1 is further improved. Further, in this case, since the organic EL layer 12 can be formed, for example, as a solid film (formed on one side), the process load can be further reduced, for example, as compared with the case where the organic EL layer 12 is formed by patterning.

Second Embodiment
The organic EL device 1 of the present embodiment is the same as the organic EL device 1 of the first embodiment except that it further includes a phase adjustment layer 16 as shown in FIG.

  The phase adjustment layer 16 is disposed, for example, between the substrate 10 and the anode 11. However, the present invention is not limited thereto, and may be provided, for example, between the organic EL layer 12 and the cathode 13 and between the layers included in the L1 and the L2. The phase adjustment layer 16 may be provided, for example, in a plurality of layers.

The material of the phase adjustment layer 16 is, for example, a polycarbonate resin, a polyolefin resin, a norbornene resin, a polyarylate resin, a polysulfone resin, and a synthetic resin such as polyvinyl alcohol, and cellulose diacetate and cellulose triacetate (TAC resin) A transparent resin obtained by uniaxially or biaxially stretching a film made of a natural resin system such as, for example, can be used. In addition, use is made of a material having a light transmitting property and one or more selected from the group consisting of an inorganic oxide film, an inorganic oxynitride film, an inorganic nitride film, an inorganic fluoride film, and the like. Specifically, for example, a silicon oxynitride film (SiO _x N _y ), a silicon oxide film (SiO ₂ ), a silicon nitride film (SiN _x ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ) ₂ ), magnesium fluoride (MgF ₂ ) and the like. Further, as the material of the phase adjustment layer 16, for example, the same material as the protective layer having gas barrier properties can be used.

  By arranging the phase adjustment layer 16, for example, the L1 and the L2 can be adjusted. That is, in addition to or instead of changing the film thickness of each layer of the organic EL element 1, by appropriately setting the thickness of the phase adjustment layer 16, the relationship of the respective formulas in the first embodiment is satisfied. , L1 and L2 can be adjusted. Therefore, for example, the film thickness and the like of each layer of the organic EL element 1 can be set to a preferable value based on the optical and electrical characteristics such as the light emission efficiency.

  The thickness of the phase adjustment layer 16 is, for example, (1/4) λ + (1/2) pλ (p is an arbitrary integer of 0 or more, where λ is the wavelength of light emitted from the light emitting layer). ) May be used. The light emitted from the light emitting layer 123 and reflected at the interface between the substrate 10 and the anode 11 reciprocates, for example, the phase adjustment layer 16. Therefore, by setting the phase adjustment layer 16 to the above-mentioned thickness, the phase of the light can be, for example, opposite to the phase of the light not transmitted through the phase adjustment layer 16.

  The phase adjustment layer 16 may be formed of, for example, one phase adjustment layer, or a combination of a plurality of phase adjustment layers. In the latter case, the phase adjustment layer 16 is obtained by, for example, bonding the phase adjustment layer having a thickness of (1/4) λ and the phase adjustment layer having a thickness of (1/2) λ in an arbitrary order. It may be one in which a plurality of the phase adjusting layers having a thickness of (1/4) λ are laminated.

  The phase adjustment layer 16 may be disposed on the entire surface or partially disposed in the plane direction of the organic EL layer 12, for example. In the latter case, the phase adjustment layer 16 is arranged, for example, to correspond to every other gap in the cathode 13. Thus, for example, the light transmitted through the phase adjustment layer 16 and the light not transmitted through the phase adjustment layer 16 can be interfered with each other to weaken the light. For this reason, it is possible to suppress light leakage as shown by arrows in FIG.

(Embodiment 3)
The organic EL element 2 of the present embodiment is the same as the organic EL element 1 of Embodiment 1 except that it is a top emission type organic EL element instead of being a bottom emission type organic EL element. As shown in FIG. 4, the organic EL element 2 includes a substrate 20, an anode 21, an organic EL layer 22, a cathode 23, and a sealing substrate 25. On the substrate 20, the anode 21, the organic EL layer 22, the cathode 23, and the sealing substrate 25 are stacked in the above order. The organic EL layer 22 includes a hole injection layer 221, a hole transport layer 222, a light emitting layer 223, an electron transport layer 224, and an electron injection layer 225, and these are stacked in the above order. The anodes 21 are spaced apart in the form of slits.

  In the present embodiment, the optical distance between the light emitting layer 223 and the interface between the cathode 23 and the sealing substrate 25 is L1, the optical distance between the light emitting layer 223 and the interface between the organic EL layer 22 and the anode 21 is L2, and When the wavelength of the light emitted from the light emitting layer 223 is λ, the L1, the L2, and the λ satisfy the relationship of the respective expressions in the first embodiment. The light of (I) to (III) shown in FIG. 3 passes through the gap of the anode 21 and is emitted as a leaked light in the non-emission direction of the organic EL element. However, in the organic EL element 2 of the present embodiment, when the L1, the L2, and λ satisfy the relationship of the respective expressions in the embodiment 1, the light of (I) to (III) is, for example, reversed. Because the light is in phase, these lights weaken due to interference. For this reason, the leak of light as shown by the arrow in FIG. 4 can be suppressed.

(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, light emission from the non-light emitting surface side can be suppressed.

  Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. The configurations and details of the present invention can be modified in various ways that can be understood by those skilled in the art within the scope of the present invention.

  According to the present invention, light emission from the non-light emitting surface side in the organic EL element can be suppressed. Therefore, for example, according to the present invention, it is possible to provide, for example, an organic EL element having high designability.

DESCRIPTION OF SYMBOLS 1, 2 organic EL element 10, 20 board | substrate 11, 21 anode 12, 22 organic EL layer 121, 221 hole injection layer 122, 222 hole transport layer 123, 223 light emitting layer 124, 224 electron transport layer 125, 225 electron injection Layer 13, 23 Cathode 14 Intermediate layer 15, 25 Sealing substrate 16 Phase adjustment layer

Claims (10)

A substrate, a first electrode, an organic EL layer, and a second electrode,
The organic EL layer includes a light emitting layer,
The substrate, the first electrode, the organic EL layer, and the second electrode are stacked in this order,
One of the first electrode and the second electrode is an anode, and the other is a cathode.
The first electrode is a transparent electrode,
The second electrodes are spaced apart in the surface direction of the organic EL layer,
The optical distance between the light emitting layer and the interface on the side closer to the first electrode than the light emitting layer among the interfaces in the organic EL element is L1, the light emitting layer, and the organic EL layer in the second electrode When an optical distance from the interface on the facing side is L2, a relationship between the L1 and the L2 is that the interference of at least two light selected from the group consisting of the following (I) to (III) is caused by interference An organic EL device characterized in that it has a relationship of light of matching phases.
(I) Light emitted from the light emitting layer, light reflected at the interface closer to the first electrode than the light emitting layer in the interface of the organic EL element (II) emitted from the light emitting layer, the second electrode Light reflected by the interface facing the organic EL layer in the above, and light reflected by the interface closer to the first electrode than the light emitting layer (III) emitted from the light emitting layer, and the second electrode Light emitted in the direction When the wavelength of light emitted from the light emitting layer is λ, the relationship between L 1, L 2, and λ is as shown in the following formula (7), and at least one of the following formulas (5) and (6) The organic EL device according to claim 1, satisfying at least one of the relationships shown.

When the wavelength of light emitted from the light emitting layer is λ, the relationship between L 1, L 2 and λ is as shown in the following equations (1) and (2), and in the following equations (3) and (4) The organic EL device according to claim 1, which satisfies at least one of the group consisting of the relationships shown and the relationships shown in the following formulas (5) and (6).

Among the interfaces in the organic EL element, the interface closer to the first electrode than the light emitting layer is an interface on the opposite side of the first electrode to the side facing the organic EL layer. The organic EL element as described in any one of 1 to 3. The interface on the side closer to the first electrode than the light emitting layer among the interfaces on the organic EL element is an interface on the side opposite to the side facing the first electrode on the substrate. The organic EL element as described in any one of 4. The organic EL device according to any one of claims 1 to 5, wherein the second electrode is arranged in a slit shape. The organic EL device according to any one of claims 1 to 6, further comprising a phase adjustment layer. The organic EL device according to claim 7, wherein the phase adjustment layer is disposed between the substrate and the first electrode. When the wavelength of the light emitted from the light emitting layer is λ, the phase adjustment layer has a thickness of (1/4) λ + (1/2) pλ (p is an arbitrary integer of 0 or more). An organic EL device according to claim 7 or 8. The organic EL device according to claim 7, wherein the phase adjustment layer is disposed to correspond to every other gap in the second electrode.

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