WO2012161113A1

WO2012161113A1 - Organic electroluminescence element

Info

Publication number: WO2012161113A1
Application number: PCT/JP2012/062759
Authority: WO
Inventors: 将啓中村; 正人山名; 矢口　充雄; 山木　健之
Original assignee: パナソニック株式会社
Priority date: 2011-05-20
Filing date: 2012-05-18
Publication date: 2012-11-29

Abstract

This organic electroluminescence element is provided with a substrate (10), a first electrode (20) disposed on a first surface (101) of the substrate (10), second electrodes (40) that face the first electrode (20) at the first surface (101) side, and a functional layer (30) that exists between the first and second electrodes (10, 40) and includes at least a light-emitting layer (32). The resistivities of the first and second electrodes (20, 40) are less than a predetermined resistivity corresponding to the resistivity of a transparent conductive oxide. The second electrodes (40) each have an opening (41) for extracting light from the functional layer (30). The element also includes a conductive layer (50) and insulating parts (21). The conductive layer (50) is optically transparent, is disposed on the openings, and is in contact with the second electrodes (40) and the functional layer (30). The insulating parts (21) are provided in the shape of the openings (41) between the first electrode (20) and the second electrodes (40).

Description

Organic electroluminescence device

The present invention relates to an organic electroluminescence element.

9 has been proposed (Japan Patent Application Publication No. 2006-331694 (hereinafter referred to as “Reference 1”). The organic electroluminescent element of Reference 1 is composed of one electrode. A (cathode) 101 is stacked on the surface of the substrate 104, a light emitting layer 103 is stacked on the surface of the electrode 101 via an electron injection / transport layer 105, and a hole injection / transport layer 106 is stacked on the light emitting layer 103. The other electrode (anode) 102 is laminated, and this organic electroluminescence element includes a sealing member 107 on the surface side of the substrate 104. Therefore, in this organic electroluminescence element, the light emitting layer 103 is provided. The light emitted from the electrode 102 is formed as a light transmissive electrode, and the sealing member 10 is formed from a transparent body. It is adapted to be emitted through.

Examples of the material of the reflective electrode 101 include Al, Zr, Ti, Y, Sc, Ag, and In. Examples of the material of the electrode 102 which is a light transmissive electrode include indium-tin oxide (ITO) and indium-zinc oxide (IZO).

By the way, in order to light the organic electroluminescence element with high brightness, it is necessary to pass a larger current. However, since the organic electroluminescence element generally has a higher sheet resistance of an anode made of an ITO film than that of a cathode made of a metal film, an alloy film, a metal compound film, etc., the potential gradient at the anode is high. As a result, the in-plane variation in luminance increases.

In addition, as an electroluminescence lamp that solves the problems of the conventional structure including an electrode made of an ITO film formed by sputtering, an electroluminescence lamp constructed without using an electrode made of an ITO film (Japanese Patent Application Publication No. 2002-502540 (hereinafter referred to as “Document 2”). For example, as shown in FIG. 10, the first conductive layer 220, the electroluminescent material 230 are included in Document 2. There has been proposed an electroluminescent lamp 210 comprising a second conductive layer 240 and a substrate 245, wherein the first conductive layer 220 is constituted by a rectangular grid electrode having a rectangular opening 250.

Here, Document 2 describes that it is preferable to form the first conductive layer 220 and the second conductive layer 240 with conductive ink such as silver ink or carbon ink. Further, Document 2 describes that the first conductive layer 220, the electroluminescent material 230, and the second conductive layer 240 are formed by a screen printing method, an offset printing method, or the like.

Note that Document 2 describes that when the electroluminescence lamp 210 with uniform brightness is required, the density of the openings 250 is made substantially constant over the lamp surface.

By the way, in the electroluminescence lamp 210 having the configuration shown in FIG. 10, since the first conductive layer 220 has the opening 250, the carrier injection property from the first conductive layer 220 to the electroluminescent material 230 is improved. Decreases, and the external quantum efficiency decreases.

The present invention has been made in view of the above-mentioned reasons, and an object thereof is to provide an organic electroluminescence device capable of reducing luminance unevenness and improving carrier injectability. It is in.

The present invention provides a substrate (10), a first electrode (20) provided on one surface side of the substrate (10), and the first electrode (20) on the one surface side of the substrate (10). Organic electroluminescence comprising a second electrode (40) facing each other and a functional layer (30) including at least a light emitting layer (32) between the first electrode (20) and the second electrode (40). It is an element. The resistivity of each of the first electrode (20) and the second electrode (40) is lower than a predetermined resistivity, where the predetermined resistivity corresponds to the resistivity of the transparent conductive oxide. The second electrode (20) includes an opening (41) for extracting light from the functional layer (30). The organic electroluminescence device further includes a conductive layer (50), which is light transmissive and provided in the opening (41), the second electrode (40), the functional layer (30), Is in contact with The organic electroluminescence device further includes an insulating part (21), which is in the shape of the opening (41) so as to be interposed between the first electrode (20) and the second electrode (40). It is provided along.

In one embodiment, the conductive layer (50) covers the second electrode (40).

In one embodiment, the height of the conductive layer (50) in the opening (41) is lower than the height of the second electrode (40).

In one embodiment, the functional layer (30) includes a conductive polymer layer (35) as an outermost layer in contact with both the second electrode (40) and the conductive layer (50).

In one embodiment, the second electrode (40) is an anode, and the functional layer (30) includes a hole injection layer (34) on the second electrode (40) side of the light emitting layer (32). Contains.

In one embodiment, the second electrode (40) is an anode, the conductive layer (50) has a hole injection function, and the functional layer (30) includes the second electrode (40) and the conductive layer. An electron blocking layer (33) that suppresses leakage of electrons from the light emitting layer (32) side is included as the outermost layer in contact with both of the layers (50).

In one embodiment, the second electrode (40) is an anode, the conductive layer (50) has a hole injection function, and the functional layer (30) includes the second electrode (40) and the conductive layer. A conductive polymer layer (36) having a hole injection function is included as the outermost layer in contact with both layers (50).

In one embodiment, the second electrode (40) is composed of an electrode containing a metal powder and an organic binder.

In one embodiment, the conductive layer (35) is made of a transparent conductive film including a conductive nanostructure and a transparent medium, or a metal thin film having a thickness capable of transmitting light from the functional layer (30). .

In the organic electroluminescence device according to the present invention, it is possible to reduce the luminance unevenness and improve the carrier injection property.

Preferred embodiments of the invention are described in further detail. Other features and advantages of the present invention will be better understood with reference to the following detailed description and accompanying drawings.
1 is a schematic cross-sectional view of an organic electroluminescence element of Embodiment 1. FIG. 3 is a schematic plan view of a second electrode in the organic electroluminescence element of Embodiment 1. FIG. 2 is a schematic cross-sectional view of a main part of the organic electroluminescence element of Embodiment 1. FIG. 6 is a schematic plan view of another configuration example of the second electrode in the organic electroluminescence element of Embodiment 1. FIG. 6 is a schematic plan view of another configuration example of the second electrode in the organic electroluminescence element of Embodiment 1. FIG. 5 is a schematic cross-sectional view of a main part of an organic electroluminescence element of Embodiment 2. FIG. 6 is a schematic cross-sectional view of a main part of an organic electroluminescence element according to Embodiment 3. FIG. 6 is a schematic cross-sectional view of a main part of an organic electroluminescence element of Embodiment 4. FIG. It is a schematic sectional drawing of the organic electroluminescent element of a prior art example. It is the transparent upper surface and sectional drawing of the electroluminescent lamp of a prior art example.

(Embodiment 1)
Hereinafter, the organic electroluminescence device of this embodiment will be described with reference to FIGS.

The organic electroluminescence element includes a substrate 10, a first electrode 20 provided on one surface side of the substrate 10, a second electrode 40 facing the first electrode 20 on the one surface side of the substrate 10, and a first electrode. 20 and the second electrode 40 and a functional layer 30 including at least a light emitting layer 32.

In the example of FIG. 1, the substrate 10 has a first surface (upper surface) 101 and a second surface (lower surface) 102, and the first electrode 20 has the second electrode 40 facing the first electrode 20 and the first electrode 20. It is formed on the first surface 101 of the substrate 10 so that 20 is disposed between the substrate 10 and the second electrode 40. The functional layer 30 is an organic functional layer including at least a light emitting layer 32 made of an organic functional material.

The organic electroluminescence element has a first terminal portion (not shown) electrically connected to the first electrode 20 via a first lead wiring (not shown), and a second lead to the second electrode 40. And a second terminal portion 47 electrically connected via the wiring 46. The first lead wiring, the first terminal portion, the second lead wiring 46 and the second terminal portion 47 are provided on the first surface 101 side of the substrate 10. Further, in the organic electroluminescence element, the second lead wiring 46 is electrically connected to a part of the functional layer 30 (side surface in the example of FIG. 1), the first electrode 20, and the first lead wiring continuous with the first electrode 20. An insulating film 60 for providing electrical insulation is provided on the first surface 101 side of the substrate 10. That is, the insulating film 60 is formed across the first surface 101 of the substrate 10, the side surface of the first electrode 20, the side surface of the functional layer 30, and the outer peripheral portion of the surface of the functional layer 30 on the second electrode 40 side. Has been.

In the organic electroluminescence element, the resistivity of each of the first electrode 20 and the second electrode 40 is lower than a predetermined resistivity, and the predetermined resistivity is a transparent conductive oxide (Transparent Oxide: TCO). Corresponding to Examples of the transparent conductive oxide include ITO, AZO, GZO, and IZO.

Further, the second electrode 40 of the organic electroluminescence element has at least one opening 41 (see FIGS. 2 to 8) for extracting light from the functional layer 30. In the illustrated example, the second electrode 40 has a structure having a plurality of voids (openings 41) each having a thin line portion 44 intersecting each other and having a quadrilateral (rectangular shape in FIG. 2) shape therebetween.

The organic electroluminescence element further includes at least one conductive layer 50, which is light transmissive and provided in the opening 41 of the second electrode 40. The second electrode 40, the functional layer 30, Is in contact with In the example of FIG. 2, the organic electroluminescence element has one conductive layer 50, which is provided in the plurality of openings 41 of the second electrode 40 and is in contact with the second electrode 40 and the functional layer 30. ing. Thereby, the organic electroluminescence element can extract light from the second electrode 40 side. In short, the organic electroluminescence element of the present embodiment can be used as a top emission type organic electroluminescence element. As an example, the organic electroluminescence element may have a plurality of conductive layers 50. In this example, the plurality of conductive layers 50 are formed in the plurality of openings 41 so as to be in contact with the inner edges of the plurality of openings 41 and the functional layer 30, respectively. That is, in this example, each first side (upper side in FIG. 1) of the plurality of thin wire portions 44 of the second electrode 40 is not covered with the conductive layer 50.

The organic electroluminescence element is disposed opposite to the first surface 101 side of the substrate 10 and has a light-transmitting cover substrate 70, and a frame shape (a book) interposed between the peripheral portion of the substrate 10 and the peripheral portion of the cover substrate 70. In the embodiment, it is preferable to include a frame portion 80 having a rectangular frame shape. In addition, the organic electroluminescence element includes the element portion 1 including the first electrode 20, the functional layer 30, the second electrode 40, and the conductive layer 50 in a space surrounded by the substrate 10, the cover substrate 70, and the frame portion 80. It is preferable to include a sealing portion 90 made of a light-transmitting material (for example, a light-transmitting resin) to be sealed.

Hereinafter, each component of the organic electroluminescence element will be described in detail. 1 to 8, each component is different from the actual size.

The substrate 10 has a rectangular shape in plan view. Here, the planar view shape of the substrate 10 is not limited to a rectangular shape, and may be, for example, a polygonal shape or a circular shape other than the rectangular shape.

The glass substrate is used as the substrate 10, but is not limited thereto, and for example, a plastic plate or a metal plate may be used. As a material for the glass substrate, for example, soda lime glass, non-alkali glass, or the like can be employed. Moreover, as a material of the plastic plate, for example, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polycarbonate, or the like can be employed. Moreover, as a material of the metal plate, for example, aluminum, copper, stainless steel, or the like can be employed. In the case of using a plastic plate, it is preferable to suppress moisture permeation by using a plastic substrate having a SiON film, SiN film, or the like formed on the surface thereof. The substrate 10 may be rigid or flexible.

When a glass substrate is used as the substrate 10, the unevenness of the first surface 101 of the substrate 10 may cause a leak current of the organic electroluminescence element (may cause deterioration of the organic electroluminescence element). ). For this reason, when a glass substrate is used as the substrate 10, it is preferable to prepare a glass substrate for element formation that is polished with high accuracy so that the surface roughness of the first surface 101 becomes small. Regarding the surface roughness of the first surface 101 of the substrate 10, the arithmetic average roughness Ra specified in JIS B 0601-2001 (ISO 4287-1997) is preferably 10 nm or less, and is several nm or less. Is more preferable. On the other hand, when a plastic plate is used as the substrate 10, an arithmetic average roughness Ra of the first surface 101 of several nanometers or less can be obtained at a low cost without performing highly accurate polishing. Is possible.

The glass substrate is used as the cover substrate 70, but is not limited thereto, and for example, a plastic plate or the like may be used. As a material for the glass substrate, for example, soda lime glass, non-alkali glass, or the like can be employed. Moreover, as a material of the plastic plate, for example, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polycarbonate, or the like can be employed.

In the present embodiment, a flat substrate having a first surface (upper surface) 701 and a second surface (lower surface) 702 is used as the cover substrate 70. However, the present invention is not limited to this, and the surface facing the substrate 10 (first surface). 2 surface 702) having a storage recess for storing the above-described element portion 1 is used, and the peripheral portion of the storage recess on the second surface 702 is joined to the substrate 10 side over the entire circumference. Also good. In this case, there is an advantage that it is not necessary to use the frame part 80 which is a separate member. On the other hand, in the case where the flat cover substrate 70 and the frame-shaped frame portion 80 are configured by separate members, optical properties (light transmittance, refractive index, etc.) required for the cover substrate 70, There is an advantage that it is possible to employ a material that satisfies both the physical properties required for the frame portion 80 (such as gas barrier properties).

On the outer surface (first surface 701) side (the surface opposite to the substrate 10 side) of the cover substrate 70, a light extraction structure portion that suppresses reflection of light emitted from the light emitting layer 32 on the first surface 701 ( (Not shown). Examples of such a light extraction structure part include an uneven structure part having a two-dimensional periodic structure. The period of such a two-dimensional periodic structure is such that when the wavelength of light emitted from the light emitting layer 32 is in the range of 300 to 800 nm, for example, the wavelength in the medium is λ (the wavelength in vacuum is divided by the refractive index of the medium). Value), it is desirable to set appropriately within the range of 1/4 to 10 times the wavelength λ. Such an uneven structure portion is preliminarily formed on the first surface 701 side of the cover substrate 70 by an imprint method such as a thermal imprint method (thermal nanoimprint method) or an optical imprint method (photo nanoimprint method) in advance. It is possible to form. Further, depending on the material of the cover substrate 70, the cover substrate 70 may be formed by injection molding, and the uneven structure portion may be directly formed on the cover substrate 70 by using an appropriate mold at the time of injection molding. Further, the concavo-convex structure portion can also be configured by a member different from the cover substrate 70, for example, a prism sheet (for example, a light diffusion film such as Lightup (registered trademark) GM3 manufactured by Kimoto Co., Ltd.). Can be configured.

In the organic electroluminescence element of this embodiment, by providing the above-described light extraction structure portion, it is possible to reduce the reflection loss of the light emitted from the light emitting layer 32 and reaching the first surface 701 side of the cover substrate 70, and the light extraction efficiency. Can be improved.

As the first bonding material for bonding the frame portion 80 and the first surface 101 side of the substrate 10, epoxy resin is used, but not limited to this, for example, acrylic resin may be used. The epoxy resin or acrylic resin used as the first bonding material may be, for example, an ultraviolet curable type or a thermosetting type. Moreover, you may use what made the epoxy resin contain a filler (for example, a silica, an alumina, etc.) as a 1st joining material. Here, the frame portion 80 is airtightly bonded to the first surface 101 side of the substrate 10 over the entire circumference of the opposite surface (second surface 702) of the frame portion 80 to the substrate 10 side. . Moreover, as a 2nd joining material which joins the flame | frame part 80 and the cover board | substrate 70, although an epoxy resin is used, you may employ | adopt not only this but an acrylic resin, frit glass, etc., for example. The epoxy resin or acrylic resin used as the second bonding material may be, for example, an ultraviolet curable type or a thermosetting type. Moreover, you may use what made the epoxy resin contain a filler (for example, silica, alumina, etc.) as a 2nd joining material. Here, the frame portion 80 is airtightly bonded to the cover substrate 70 over the entire circumference of the surface of the frame portion 80 facing the cover substrate 70.

As a material of the insulating film 60, for example, polyimide resin, novolac resin, epoxy resin, or the like can be used.

As the translucent material that is a material of the sealing portion 90, for example, a translucent resin such as an epoxy resin or a silicone resin can be used, but a material having a small refractive index difference from the functional layer 30 is more preferable. . The light transmissive material may be a light transmissive resin mixed with a light diffusing material made of glass or the like. Further, as the translucent material, an organic / inorganic hybrid material in which an organic component and an inorganic component are mixed and bonded at the nm level or molecular level may be used.

In the organic electroluminescence element of this embodiment, the first electrode 20 constitutes a cathode and the second electrode 40 constitutes an anode, but the organic electroluminescence element further includes an insulating part 21. That is, the second electrode 40 has substantially the same size as the first electrode 20, and the insulating portion 21 is interposed between the first electrode 20 and the second electrode 40 (all or a part thereof) It is provided along the shape of the opening 41 of the second electrode 40. That is, the insulating portion 21 is interposed between the first electrode 20 and the second side (lower side in FIG. 1) of the second electrode 40 (all or a part thereof). 1 and 2, the planar view shape of the insulating portion 21 is substantially the same as that of a part of the second electrode 40 (a part excluding a quadrilateral (rectangular) outer edge). As an example, the planar view shape of the insulating portion 21 may be substantially the same as that of the second electrode 40. In this example, the insulating part 21 is further interposed between the first electrode 20 and the remaining part of the second electrode 40 (outer edge of a quadrilateral (rectangular) shape). Such an insulating part 21 can be formed, for example, by printing a resin solution such as polyimide resin, novolac resin, or epoxy resin by a screen printing method or the like. The insulating part 21 formed in this way has a higher resistivity than that of the functional layer 30. On the other hand, the functional layer 30 includes a first carrier injection layer 31, a light emitting layer 32, an interlayer 33, and a second carrier injection layer 34 in this order from the first electrode 20 side. Here, the first carrier injected from the first electrode 20 into the functional layer 30 is an electron, and the second carrier injected from the second electrode 40 into the functional layer 30 is a hole. Therefore, the first carrier injection layer 31 is an electron injection layer, and the second carrier injection layer 34 is a hole injection layer. At this time, since the insulating portion 21 has a higher resistivity than the functional layer 30, the electrons as the first carrier and the holes as the second carrier are preferentially recombined in the light emitting layer 32 immediately below the opening 41. Lights up. When the first electrode 20 forms an anode and the second electrode 40 forms a cathode, for example, a hole injection layer is used as the first carrier injection layer 31 and an electron injection layer is used as the second carrier injection layer 34. The hole blocking layer may be provided instead of the electron blocking layer 33 as the outermost layer of the functional layer 30. Furthermore, in this case as well, the insulating portion 21 may be provided between the first electrode 20 and the second electrode 40 as described above.

The structure of the functional layer 30 described above is not limited to the example of FIG. 1. For example, an electron transport layer is provided as a first carrier transport layer between the first carrier injection layer 31 and the light emitting layer 32, or second carrier injection is performed. A structure in which a hole transport layer is provided as a second carrier transport layer between the layer 34 and the interlayer 33 may be used. Further, the functional layer 30 only needs to include at least the light emitting layer 32 (that is, the functional layer 30 may be only the light emitting layer 32), and the first carrier injection layer 31 and the first carrier transport other than the light emitting layer 32 may be used. The layer, the interlayer 33, the second carrier transport layer, the second carrier injection layer 34, and the like may be provided as appropriate. The light emitting layer 32 may have a single layer structure or a multilayer structure. For example, when the desired emission color is white, the emission layer may be doped with three types of dopant dyes of red, green, and blue, or the blue hole-transporting emission layer and the green electron-transporting property. A laminated structure of a light emitting layer and a red electron transporting light emitting layer may be adopted, or a laminated structure of a blue electron transporting light emitting layer, a green electron transporting light emitting layer and a red electron transporting light emitting layer may be adopted. Good.

Examples of the material of the light emitting layer 32 include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, and the like, polyfluorene derivatives, polyvinylcarbazole derivatives, dye bodies, and metal complex light emitting materials. Such as anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, quinoline metal complex, tris (8-hydroxyquinolinato) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8-quinolinato) Luminium complex, aminoquinoline metal complex, benzoquinoline metal complex, tri- (p-terphenyl-4-yl) amine, pyran, quinacridone, rubrene, and derivatives thereof, or 1-aryl-2,5-di ( And 2-thienyl) pyrrole derivatives, distyrylbenzene derivatives, styrylarylene derivatives, styrylamine derivatives, and compounds having a group consisting of these luminescent compounds in a part of the molecule. In addition to fluorescent dye-derived compounds represented by the above compounds, so-called phosphorescent materials, for example, luminescent materials such as iridium complexes, osmium complexes, platinum complexes, and europium complexes, or compounds or polymers having these in the molecule Can also be suitably used. These materials can be appropriately selected and used as necessary. The light emitting layer 32 is preferably formed by a wet process such as a coating method (for example, spin coating method, spray coating method, die coating method, gravure printing method, screen printing method, etc.). However, the method for forming the light emitting layer 32 is not limited to the coating method, and the light emitting layer 32 may be formed by a dry process such as a vacuum deposition method or a transfer method.

Examples of the material for the electron injection layer include metal fluorides such as lithium fluoride and magnesium fluoride, metal halides such as sodium chloride and magnesium chloride, titanium, zinc, magnesium, calcium, An oxide such as barium or strontium can be used. In the case of these materials, the electron injection layer can be formed by a vacuum deposition method. As the material for the electron injection layer, for example, an organic semiconductor material mixed with a dopant (such as an alkali metal) that promotes electron injection can be used. In the case of such a material, the electron injection layer can be formed by a coating method.

The material for the electron transport layer can be selected from the group of compounds having electron transport properties. Examples of this type of compound include metal complexes known as electron transport materials such as Alq ₃ and compounds having a heterocycle such as phenanthroline derivatives, pyridine derivatives, tetrazine derivatives, oxadiazole derivatives, etc. Instead, any generally known electron transport material can be used.

As a material for the hole transport layer, a low molecular material or a polymer material having a low LUMO (Lowest Unoccupied Molecular Molecular) level can be used. Examples thereof include polymers containing aromatic amines such as polyvinyl carbazole (PVCz), polyarylene derivatives such as polypyridine and polyaniline, and polyarylene derivatives having aromatic amines in the main chain, but are not limited thereto. . Examples of the material for the hole transport layer include 4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD) and N, N′-bis (3-methylphenyl). -(1,1'-biphenyl) -4,4'-diamine (TPD), 2-TNATA, 4,4 ', 4 "-tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (MTDATA), 4,4′-N, N′-dicarbazole biphenyl (CBP), spiro-NPD, spiro-TPD, spiro-TAD, TNB, and the like can be used.

Examples of the material for the hole injection layer include organic materials including thiophene, triphenylmethane, hydrazoline, amiramine, hydrazone, stilbene, triphenylamine, and the like. Specifically, for example, polyvinyl carbazole, polyethylenedioxythiophene: polystyrene sulfonate (PEDOT: PSS), aromatic amine derivatives such as TPD, etc., these materials may be used alone, or two or more kinds of materials. May be used in combination. Such a hole injection layer can be formed by a wet process such as a coating method (spin coating method, spray coating method, die coating method, gravure printing method, etc.).

The interlayer 33 has a carrier blocking function (here, an electron barrier) that suppresses leakage of first carriers (here, electrons) from the light emitting layer 32 side to the second electrode 40 side. Then, it is preferable to have an electronic blocking function. Furthermore, the interlayer 33 preferably has a function of transporting second carriers (here, holes) to the light emitting layer 32, a function of suppressing quenching of the excited state of the light emitting layer 32, and the like. In the present embodiment, the interlayer 33 constitutes an electron blocking layer that suppresses leakage of electrons from the light emitting layer 32 side.

In the organic electroluminescence element, by providing the interlayer 33, it becomes possible to improve the luminous efficiency and extend the life. As the material of the interlayer 33, for example, polyarylamine or a derivative thereof, polyfluorene or a derivative thereof, polyvinylcarbazole or a derivative thereof, a triphenyldiamine derivative, or the like can be used. Such an interlayer 33 can be formed by a wet process such as a coating method (spin coating method, spray coating method, die coating method, gravure printing method, etc.).

The cathode is an electrode for injecting electrons (first carriers) that are first charges into the functional layer 30. When the first electrode 20 is a cathode, it is preferable to use an electrode material made of a metal, an alloy, an electrically conductive compound, and a mixture thereof having a low work function as the material of the cathode. It is preferable to use a work function having a work function of 1.9 eV or more and 5 eV or less so that the difference between the two is not too large. Examples of the electrode material for the cathode include aluminum, silver, magnesium, gold, copper, chromium, molybdenum, palladium, tin, and alloys of these with other metals, such as magnesium-silver mixture, magnesium-indium mixture, aluminum -Lithium alloys can be mentioned as examples. Moreover, it consists of a metal, a metal oxide, etc., and a mixture of these and other metals, for example, an ultra-thin film made of aluminum oxide (here, a thin film of 1 nm or less capable of flowing electrons by tunnel injection) and aluminum. A laminated film with a thin film can also be used. When the cathode is a reflective electrode, the cathode material is preferably a metal having a high reflectance with respect to light emitted from the light emitting layer 32 and a low resistivity, and preferably aluminum or silver. When the first electrode 20 forms an anode that is an electrode for injecting holes (second carriers) that are second charges into the functional layer 30, the material of the first electrode 20 is a work function It is preferable to use a large metal, and it is preferable to use a metal having a work function of 4 eV or more and 6 eV or less so that the difference from the HOMO (Highest Occupied Molecular Orbital) level does not become too large.

The second electrode 40 is made of an electrode containing metal powder and an organic binder. As this type of metal, for example, silver, gold, copper or the like can be employed. As a result, the organic electroluminescence element can reduce the resistivity and sheet resistance of the second electrode 40 as compared with the case where the second electrode 40 is a thin film formed of a conductive transparent oxide. It is possible to reduce luminance unevenness by reducing the resistance of the two electrodes 40. As the conductive material of the second electrode 40, an alloy, carbon black, or the like can be used instead of a metal.

The second electrode 40 can be formed, for example, by printing a paste (printing ink) in which an organic binder and an organic solvent are mixed with metal powder by, for example, a screen printing method or a gravure printing method. Examples of the organic binder include acrylic resin, polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polystyrene, polyether sulfone, polyarylate, polycarbonate resin, polyurethane, polyacrylonitrile, polyvinyl acetal, polyamide, polyimide, and diacryl phthalate resin. , Cellulose resins, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, other thermoplastic resins, and copolymers of two or more monomers constituting these resins, but are not limited thereto. It is not something.

In the organic electroluminescence device of this embodiment, the thickness of the first electrode 20 is 80 to 200 nm, the thickness of the first carrier injection layer 31 is 5 to 50 nm, the thickness of the light emitting layer 32 is 60 to 100 nm, The film thickness of the layer 33 is set to 15 nm, and the film thickness of the second carrier injection layer 34 is set to 10 to 100 nm, but these numerical values are merely examples and are not particularly limited.

As shown in FIGS. 1 and 2, the second electrode 40 is formed in a lattice shape (mesh shape) and has a plurality (36 in the example shown in FIG. 2) of opening portions 41. Here, in the second electrode 40 shown in FIG. 2, each opening 41 has a square shape. In short, the second electrode 40 shown in FIG. 2 is formed in a square lattice shape.

The second electrode 40 has, for example, a line width L1 (see FIG. 3) of 1 μm to 100 μm and a height H1 (see FIG. 3) regarding the dimensions of the square-lattice electrode pattern 40a constituting the second electrode 40. 50 nm to 100 μm and the pitch P 1 (see FIG. 3) may be set to 100 μm to 2000 μm. However, the numerical ranges of the line width L1, the height H1, and the pitch P1 of the electrode pattern 40a of the second electrode 40 are not particularly limited, and may be set as appropriate based on the planar size of the element portion 1. Here, the line width L1 of the electrode pattern 40a of the second electrode 40 is preferably narrow from the viewpoint of the utilization efficiency of the light emitted from the light emitting layer 32, and luminance unevenness is reduced by reducing the resistance of the second electrode 40. Therefore, it is preferable that the width is appropriately set based on the planar size of the organic electroluminescence element. Regarding the height H1 of the second electrode 40, from the viewpoint of lowering the resistance of the second electrode 40, the use efficiency of the material of the second electrode 40 when the second electrode 40 is formed by a coating method such as a screen printing method. From the viewpoint of (material use efficiency), the viewpoint of the emission angle of light emitted from the functional layer 30, and the like, 100 nm or more and 10 μm or less are more preferable.

Further, in the organic electroluminescence element of the present embodiment, each opening 41 in the second electrode 40 has an opening shape in which the opening area gradually increases as the distance from the functional layer 30 increases, as shown in FIGS. is there. Thereby, the organic electroluminescence element can increase the spread angle of the light emitted from the functional layer 30, and can further reduce the luminance unevenness. In addition, the organic electroluminescence element can reduce reflection loss and absorption loss at the second electrode 40, and can further improve the external quantum efficiency.

When the second electrode 40 has a lattice shape, the shape of each of the plurality of openings 41 is not limited to a square shape, and may be, for example, a rectangular shape, a regular triangle shape, or a regular hexagonal shape.

The second electrode 40 has a triangular lattice shape when each shape of the opening 41 is a regular triangle, and has a hexagonal lattice shape when each shape of the opening 41 is a regular hexagon. The second electrode 40 is not limited to a lattice shape, and may be, for example, a comb shape or may be configured by two comb-shaped electrode patterns. Further, the number of the openings 41 is not particularly limited, and the number of the second electrodes 40 is not limited to a plurality, and may be one. For example, when the second electrode 40 has a comb shape or is formed of two comb-shaped electrode patterns, the number of openings 41 can be one.

Further, the second electrode 40 may have a planar shape as shown in FIG. 4, for example. That is, the second electrode 40 has a constant line width of the linear thin line portion 44 in the electrode pattern 40a in plan view, and the interval between the adjacent thin line portions 44 as it approaches the central portion from the peripheral portion of the second electrode 40. It is good also as a shape which becomes narrow and the opening area of the opening part 41 becomes small. In the organic electroluminescence element, the second electrode 40 has a planar shape as shown in FIG. 4, so that the second terminal portion 47 in the second electrode 40 is compared with the planar shape as shown in FIG. 2. It becomes possible to improve the light emission efficiency in the central part far from the peripheral part (see FIG. 1), and to improve the external quantum efficiency. Further, the organic electroluminescence element has the first terminal portion of the functional layer 30 as compared with the case where the planar shape as shown in FIG. 2 is obtained by making the planar shape of the second electrode 40 as shown in FIG. In addition, since it is possible to suppress current concentration in the peripheral portion where the distance from the second terminal portion 47 is short, it is possible to extend the life.

Further, the second electrode 40 may have a planar shape as shown in FIG. 5, for example. That is, the second electrode 40 has a line width of the four first thin wire portions 42 on the outermost periphery of the second electrode 40 and a pair of first thin wire portions 42 and 42 (in the horizontal direction in FIG. The line width of one second thin line portion 43 in the center) is defined as a plurality of thin line portions (third thin line portions) between each of the pair of first thin line portions (42) and the second thin line portion 43. It is wider than 44. In the organic electroluminescence element, the second electrode 40 has a planar shape as shown in FIG. 5, so that the second terminal portion 47 (see FIG. 1) of the second electrode 40 is compared with the planar shape as shown in FIG. 2. It is possible to improve the light emission efficiency in the central part far from the peripheral part, and it is possible to improve the external quantum efficiency. When the second electrode 40 has a planar shape as shown in FIG. 5, the height of the first thin wire portion 42 and the second thin wire portion 43 having a relatively wide line width is higher than the height of the third thin wire portion 44. By increasing the height, it is possible to further reduce the resistance of each of the first thin wire portion 42 and the second thin wire portion 43.

In addition, the conductive layer 50 is preferably composed of either a transparent conductive film including a conductive nanostructure and a transparent medium, or a metal thin film having a thickness capable of transmitting light from the functional layer 30. The conductive layer 50 has a function as a second carrier injection path from the second electrode 40 to the functional layer 30. The second carrier is a hole when the second electrode 40 is an anode, and an electron when the second electrode 40 is a cathode. The insulating part 21 is in contact directly under the second electrode 40, and the insulating part 21 has a higher resistivity than the conductive layer 50. Therefore, the injection of the second carrier from the second electrode 40 to the functional layer 30 is preferentially performed through the interface between the second electrode 40 and the conductive layer 50 and the interface between the conductive layer 50 and the functional layer 30. It becomes. Here, as the resistivity of the conductive layer 50 is lower, the lateral conductivity from the second electrode 40 is improved, and the in-plane variation of the current flowing through the light emitting layer 32 can be reduced, resulting in uneven luminance. It becomes possible to reduce. On the other hand, the first carrier is an electron when the first electrode 20 is a cathode, and is a hole when the first electrode 20 is an anode. Here, when there is no insulating part 21, it is estimated that the injection | pouring of the 1st carrier from the 1st electrode 20 to the functional layer 30 is performed through the whole interface which the 1st electrode 20 and the functional layer 30 have contacted. Is done. On the other hand, when the insulating portion 21 is provided as in the present embodiment, the injection of the first carrier from the first electrode 20 to the functional layer 30 is performed at the interface between the first electrode 20 and the functional layer 30. Of these, it is preferentially performed through a location where the insulating portion 21 is not provided (a location facing the opening 41). Then, light emission due to recombination of the first carrier and the second carrier can be performed in a portion immediately below the opening 41, and as a result, the external quantum efficiency can be improved.

As the conductive nanostructure, conductive nanoparticles, conductive nanowires, or the like can be used. The particle diameter of the conductive nanoparticles is preferably 1 to 100 nm. The diameter of the conductive nanowire is preferably 1 to 100 nm.

As the material for the conductive nanostructure, for example, silver, gold, ITO, IZO and the like can be employed. Examples of the binder that is a transparent medium include acrylic resin, polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polystyrene, polyethersulfone, polyarylate, polycarbonate resin, polyurethane, polyacrylonitrile, polyvinyl acetal, polyamide, polyimide, diethylene. Examples include acrylic phthalate resin, cellulose resin, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, other thermoplastic resins, and copolymers of two or more monomers constituting these resins. It is not limited to. However, it is preferable to use a conductive polymer such as polythiophene, polyaniline, polypyrrole, polyphenylene, polyphenylene vinylene, polyacetylene, polycarbazole as the binder. These may be used alone or in combination. The conductive layer 50 can further improve conductivity by adopting a conductive polymer as a binder. Moreover, as a binder, in order to improve electroconductivity, you may employ | adopt what doped dopants, such as a sulfonic acid, a Lewis acid, a proton acid, an alkali metal, an alkaline-earth metal, for example.

Further, when the conductive layer 50 is formed of a metal thin film as described above, for example, silver or gold can be employed as the material of the metal thin film. The thickness of this type of metal thin film may be 30 nm or less, but is preferably 20 nm or less and more preferably 10 nm or less from the viewpoint of light transmittance. However, if the thickness is too thin, the effect of improving the injection property of the second carrier to the functional layer 30 along the path from the second electrode 40 through the conductive layer 50 is reduced.

In the organic electroluminescence element of the present embodiment described above, the resistivity of each of the first electrode 20 and the second electrode 40 is lower than a predetermined resistivity, and the predetermined resistivity corresponds to the resistivity of the transparent conductive oxide. To do. Further, the second electrode 40 has at least one opening 41 for extracting light from the functional layer 30, and the organic electroluminescence element further includes a conductive layer 50. The conductive layer 50 has optical transparency, is provided in the opening 41, and is in contact with the second electrode 40 and the functional layer 30. The organic electroluminescence element further includes an insulating portion 21, which is provided so as to be interposed between the first electrode 20 and the second electrode 40. Therefore, it is possible to reduce luminance unevenness and improve carrier (second carrier) injectability.

In this organic electroluminescence element, it is preferable that the conductive layer 50 covers the second electrode 40 as shown in FIG. Thereby, in an organic electroluminescent element, it becomes possible to improve the injectability of the carrier from the 2nd electrode 40 to the functional layer 30 more.

Moreover, in this organic electroluminescence element, as shown in FIG. 3, the height of the conductive layer 50 in the opening 41 of the second electrode 40 is preferably lower than the height H1 of the second electrode 40. Thereby, in an organic electroluminescent element, it becomes possible to reduce the optical loss in the electroconductive layer 50, and it becomes possible to aim at the improvement of external quantum efficiency.

Further, in this organic electroluminescence element, as shown in FIG. 3, the second electrode 40 is an anode, and the functional layer 30 includes a hole injection layer 34 on the second electrode 40 side with respect to the light emitting layer 32. Preferably it is. Thereby, in the organic electroluminescence element, it is possible to more efficiently inject holes as second carriers into the light emitting layer 32, and as a result, it is possible to improve the external quantum efficiency.

(Embodiment 2)
The organic electroluminescence element of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 6, the functional layer 30 is conductive as the outermost layer where both the second electrode 40 and the conductive layer 50 are in contact. The difference is that the conductive polymer layer 35 is included. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

The conductive polymer layer 35 can be formed of a transparent conductive film including a conductive nanostructure and a transparent medium, like the conductive layer 50.

In the organic electroluminescence element of the present embodiment, the functional layer 30 includes the conductive polymer layer 35 as the outermost layer where both the second electrode 40 and the conductive layer 50 are in contact with each other, and thus flows to the light emitting layer 32. It becomes possible to further reduce the in-plane variation of the current and to further reduce the luminance unevenness.

(Embodiment 3)
The organic electroluminescence element of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIG. 7, the conductive layer 50 has a hole injection function, and the functional layer 30 includes the second electrode 40 and the conductive layer. 50 is different in that, for example, an interlayer (carrier (electron) blocking layer) 33 is included as the outermost layer in contact with 50. Moreover, in the organic electroluminescent element of this embodiment, since the conductive layer 50 has a hole injection function, the second carrier injection layer 34 as the hole injection layer described in the first embodiment is not provided. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

In the organic electroluminescence element of this embodiment, the second electrode 40 is an anode, the conductive layer 50 has a hole injection function, and the functional layer 30 is the most in contact with both the second electrode 40 and the conductive layer 50. Since the interlayer 33 is included as a surface layer (including an electron blocking layer that suppresses leakage of electrons from the light emitting layer 32 side), it is possible to further reduce luminance unevenness.

(Embodiment 4)
The organic electroluminescence element of this embodiment is substantially the same as that of Embodiment 1, and as shown in FIG. 8, the conductive layer 50 has a hole injection function, and the functional layer 30 includes the second electrode 40 and the conductive layer. 50 is different in that, for example, a conductive polymer layer 36 having a hole injection function is included as the outermost layer in contact with both. Moreover, in the organic electroluminescent element of this embodiment, since the conductive layer 50 has a hole injection function, the second carrier injection layer 34 as the hole injection layer described in the first embodiment is not provided. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably.

The conductive polymer layer 36 having a hole injection function can be formed by, for example, the conductive nanostructure and the conductive polymer described in the first embodiment.

In the organic electroluminescence element of this embodiment, the second electrode 40 is an anode, the conductive layer 50 has a hole injection function, and the functional layer 30 is the most in contact with both the second electrode 40 and the conductive layer 50. Since the conductive polymer layer 36 having the hole injection function is included as the surface layer, the luminance unevenness can be further reduced.

The organic electroluminescent elements described in Embodiments 1 to 4 can be suitably used as, for example, an organic electroluminescent element for illumination, but can be used not only for illumination but also for other applications.

While the invention has been described in terms of several preferred embodiments, various modifications and variations can be made by those skilled in the art without departing from the true spirit and scope of the invention, ie, the claims.

Claims

A substrate, a first electrode provided on one surface side of the substrate, a second electrode facing the first electrode on the one surface side of the substrate, and between the first electrode and the second electrode And an organic electroluminescence device comprising at least a functional layer including a light emitting layer,
Resistivity of each of the first electrode and the second electrode is lower than a predetermined resistivity, where the predetermined resistivity corresponds to the resistivity of the transparent conductive oxide,
The second electrode includes an opening for extracting light from the functional layer;
The organic electroluminescence element further includes a conductive layer, which has light transmittance, is provided in the opening, is in contact with the second electrode and the functional layer,
The organic electroluminescence device further includes an insulating portion, which is provided along the shape of the opening so as to be interposed between the first electrode and the second electrode. element.
The organic electroluminescent element according to claim 1, wherein the conductive layer covers the second electrode.
The organic electroluminescent element according to claim 1 or 2, wherein a height of the conductive layer in the opening is lower than a height of the second electrode.
The said functional layer contains the electroconductive polymer layer as an outermost layer which both the said 2nd electrode and the said electroconductive layers contact | connect, The Claim 1 thru | or 3 characterized by the above-mentioned. Organic electroluminescence device.
The said 2nd electrode is an anode, The said functional layer contains the hole injection layer which exists in the said 2nd electrode side rather than the said light emitting layer, The Claim 1 thru | or 4 characterized by the above-mentioned. Organic electroluminescence element.
The second electrode is an anode, the conductive layer has a hole injection function, and the functional layer is an outermost layer in contact with both the second electrode and the conductive layer. The organic electroluminescent device according to claim 1, further comprising an electron blocking layer that suppresses leakage of the organic electroluminescence device.
The second electrode is an anode, the conductive layer has a hole injection function, and the functional layer is a conductive layer having a hole injection function as an outermost layer in contact with both the second electrode and the conductive layer. The organic electroluminescent element according to claim 1, further comprising a conductive polymer layer.
The organic electroluminescent element according to any one of claims 1 to 7, wherein the second electrode is made of an electrode containing a metal powder and an organic binder.
9. The conductive layer according to claim 1, wherein the conductive layer comprises a transparent conductive film including a conductive nanostructure and a transparent medium, or a metal thin film having a thickness capable of transmitting light from the functional layer. The organic electroluminescent element as described in any one.