JP5334888B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device.

  Conventionally, light emitting devices using organic electroluminescence elements (hereinafter abbreviated as organic EL elements) have been researched and developed in various places.

  As an organic EL element, for example, a transparent electrode serving as an anode, a hole transport layer, a light emitting layer (organic light emitting layer), an electron injecting layer, and an electrode serving as a cathode are laminated on one surface side of a translucent substrate (transparent substrate). Those with a structure are known. In this type of organic EL element, light emitted from the light emitting layer by applying a voltage between the anode and the cathode is taken out through the transparent electrode and the translucent substrate.

  The organic EL element is a self-luminous light emitting element, has a relatively high light emission characteristic, and can emit light in various colors, and has a feature such as a display device (for example, Applications such as light emitters such as flat panel displays) and light sources (for example, backlights of liquid crystal display devices and illumination light sources) are expected, and some have already been put into practical use.

  However, in order to apply and deploy organic EL elements for these uses, development of organic EL elements with higher efficiency, longer life, and higher brightness is desired.

  As an example of a light-emitting device for the purpose of extending the life and facilitating external connection from the light extraction surface side, a light-transmitting first substrate and one surface side of the first substrate are formed. The organic EL element (element part) and the external connection that is disposed opposite to the first substrate so as to sandwich the organic EL element, and is electrically connected to each of the first electrode and the second electrode of the organic EL element A frame-shaped sealing portion formed between the first substrate and the second substrate so as to surround the organic EL element, the second substrate having the first electrode terminal and the second electrode terminal And a first connection part that connects the first electrode and the first electrode terminal, and a second connection part that connects the second electrode and the second electrode terminal. There has been proposed a light emitting device in which a part and a second connection part are arranged outside a sealing part (Patent Document 1). Here, the sealing portion is formed of a sealing resin such as an epoxy resin, and the first connection portion and the second connection portion are formed of a plating layer or cream solder.

JP 2008-186618 A

  However, in the light emitting device disclosed in Patent Document 1, the sealing portion that surrounds the organic EL element by joining the first substrate and the second substrate is formed of a sealing resin such as an epoxy resin. Therefore, the airtightness is insufficient, and the life is shortened due to the influence of moisture and gas entering from the outside (for example, oxygen, gas generated from cream solder, etc.). In Patent Document 1, the space surrounded by the first substrate, the second substrate, and the sealing portion is made an inert gas atmosphere, or the organic EL element is covered with a protective film such as polyimide, and the protective film Although a structure in which a sealing portion is formed so as to cover the surface of the organic EL element has been proposed, it is desired to develop a light emitting device that can more reliably prevent external moisture and gas from reaching the organic EL element. ing.

  The present invention has been made in view of the above reasons, and its purpose is to facilitate external connection from the light extraction surface side and to further reduce the lifetime while suppressing a decrease in light extraction efficiency. An object of the present invention is to provide a light emitting device that can be realized.

  The invention according to claim 1 is an organic EL element having a light emitting layer between a pair of electrodes spaced in the thickness direction, and a wiring layer electrically connected to each of the electrodes of the organic EL element. An organic EL element unit formed on the front surface side, a first cover substrate formed using the first glass substrate and disposed on the other surface side of the plastic film in the organic EL element unit; A second glass substrate is formed on the organic EL element side of the organic EL element unit and is hermetically bonded to the first cover substrate with frit glass so as to cover the organic EL element unit. A cover substrate; and a frame-shaped spacer portion interposed between the peripheral portion of the organic EL element unit and the first cover substrate. Comprises a concavo-convex structure portion that is provided on the other surface side of the plastic film and suppresses reflection of light emitted from the organic EL element on the other surface, and the surface of the concavo-convex structure portion and the first cover substrate The first cover substrate is electrically connected to each wiring layer in the projection area of the organic EL element unit on the one surface side opposite to the organic EL element unit side. A plurality of external connection electrodes to be connected, and the external connection electrodes and the wiring layer overlapping in the thickness direction of the first cover substrate are formed of the first cover substrate, the spacer portion, and the plastic film; It is characterized in that it is electrically connected through a through wiring penetrating in the thickness direction of the laminate.

  According to a second aspect of the present invention, in the first aspect of the invention, peripheral portions of the first cover substrate and the second cover substrate are in contact with each other, and an outer peripheral edge of the first cover substrate and the first cover substrate are in contact with each other. The first cover substrate and the second cover are formed by a sealing portion made of the frit glass that is formed across the outer peripheral edge of the two cover substrates and seals the boundary between the two outer peripheral edges over the entire periphery. The substrate is hermetically bonded.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, a liquid having a higher thermal conductivity than the inert gas is formed between the organic EL element unit and the second cover substrate. It is characterized by interposing a medium for sealing the organic EL element.

  According to the first aspect of the present invention, there is an effect that the external connection from the light extraction surface side is easy and the life can be further extended while suppressing the decrease of the light extraction efficiency.

1 is a schematic cross-sectional view of a light emitting device according to Embodiment 1. FIG. 6 is a schematic cross-sectional view of a light emitting device according to Embodiment 2. FIG.

(Embodiment 1)
Hereinafter, the light-emitting device of this embodiment will be described with reference to FIG.

  In the light emitting device of the present embodiment, the organic EL element 11 and the wiring layers 15 and 17 electrically connected to the anode 12 and the cathode 14 of the organic EL element 11 are formed on one surface side of the transparent plastic film 10, respectively. An organic EL element unit 1 is provided. In the present embodiment, the anode 12 and the cathode 14 constitute a pair of electrodes separated in the thickness direction.

  In addition, the light emitting device uses a first cover substrate 2 that is formed using the first glass substrate and is disposed on the other surface side of the plastic film 10 in the organic EL element unit 1, and a second glass substrate. A second cover substrate 3 formed and disposed on the organic EL element unit 1 side of the organic EL element unit 1 and hermetically bonded to the first cover substrate 2 so as to cover the organic EL element unit 1. . Here, the second cover substrate 3 is hermetically bonded to the first cover substrate 2 by a sealing portion 5 made of frit glass. More specifically, the peripheral part of the 2nd glass substrate 3 and the peripheral part of the 1st glass substrate 2 are joined over the perimeter by the sealing part 5. FIG. In the present embodiment, the first cover substrate 2, the second cover substrate 3, and the sealing portion 5 constitute an airtight package in which the organic EL element unit 1 is accommodated.

  The light emitting device also includes a frame-like spacer portion 4 interposed between the peripheral portion of the organic EL element unit 1 and the first cover substrate 2. In addition, the light emitting device includes an uneven structure portion 19 in which the organic EL element unit 1 is provided on the other surface side of the plastic film 10 and suppresses reflection of light emitted from the organic EL element 11 on the other surface, A space 6 exists between the surface of the uneven structure portion 19 and the first cover substrate 2.

  The first cover substrate 2 has a plurality of external connections electrically connected to the respective wiring layers 15 and 17 in the projection region of the organic EL element unit 1 on the one surface side opposite to the organic EL element unit 1 side. Electrodes 25 and 27 are provided. In the light emitting device, the external connection electrodes 25 and 27 and the wiring layers 15 and 17 that overlap in the thickness direction of the first cover substrate 2 are laminated bodies of the first cover substrate 2, the spacer portion 4, and the plastic film 10. Are electrically connected through through wirings 85 and 87 penetrating in the thickness direction.

  Hereinafter, each component will be described in detail.

  In the organic EL element 11, an organic EL layer 13 interposed between an anode 12 and a cathode 14 includes a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer in this order from the anode 12 side. Here, in the organic EL element 11, the anode 12 is laminated on the one surface side of the plastic film 10, and the cathode 14 faces the anode 12 on the opposite side of the anode 12 from the plastic film 10 side. The positional relationship between the anode 12 and the cathode 14 may be reversed.

  In the organic EL element unit 1 in the present embodiment, the anode 12 of the organic EL element 11 is constituted by a transparent electrode, and the cathode 14 is constituted by an electrode that reflects light from the light emitting layer. Light is extracted from the side.

  The laminated structure of the organic EL layer 13 is not limited to the above-described example. For example, a single-layer structure of a light emitting layer, a laminated structure of a hole transport layer, a light emitting layer, and an electron transport layer, or a hole transport layer and a light emitting layer. Or a stacked structure of a light emitting layer and an electron transport layer. A hole injection layer may be interposed between the anode and the hole transport layer. Further, the light emitting layer may have a single layer structure or a multilayer structure. For example, when the desired light emission color is white, the light emission layer may be doped with three types of dopant dyes of red, green, and blue. Alternatively, a laminated structure of a blue hole transporting light emitting layer, a green electron transporting light emitting layer and a red electron transporting light emitting layer may be adopted, or a blue electron transporting light emitting layer and a green electron transporting light emitting layer may be employed. A laminated structure with a red electron transporting light emitting layer may be adopted.

  The anode 12 is an electrode for injecting holes into the light emitting layer, and it is preferable to use an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function, and HOMO (Highest Occupied Molecular). Orbital) It is preferable to use a work function of 4 eV or more and 6 eV or less so that the difference from the level does not become too large. Examples of the electrode material of the anode 12 include ITO, IZO, tin oxide, zinc oxide, copper iodide, conductive polymers such as PEDOT and polyaniline, and conductive polymers doped with any acceptor, carbon nanotubes, and the like. The conductive light transmissive material can be exemplified. Here, the anode 12 may be formed as a thin film on the one surface side of the plastic film 10 by a sputtering method, a vacuum deposition method, a coating method, or the like.

  The sheet resistance of the anode 12 is preferably several hundred Ω / □ or less, particularly preferably 100 Ω / □ or less. Here, the film thickness of the anode 12 varies depending on the light transmittance of the anode 12, the sheet resistance, and the like, but is set to 500 nm or less, preferably in the range of 10 nm to 200 nm.

  The cathode 14 is an electrode for injecting electrons into the light emitting layer, and 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, and LUMO (Lowest Unoccupied It is preferable to use a material having a work function of 1.9 eV or more and 5 eV or less so that the difference from the molecular orbital level does not become too large. Examples of the electrode material of the cathode 14 include aluminum, silver, magnesium and the like, and alloys of these with other metals, such as a magnesium-silver mixture, a magnesium-indium mixture, and an aluminum-lithium alloy. Also, a metal conductive material, a metal oxide, etc., and a mixture of these and other metals, for example, an ultrathin film made of aluminum oxide (here, a thin film of 1 nm or less capable of flowing electrons by tunnel injection) A laminated film with a thin film made of aluminum can also be used. Moreover, when taking out light from the cathode 14 side, ITO, IZO, etc. should just be employ | adopted, for example.

  As a material for the light emitting layer, any material known as a material for an organic EL element can be used. For example, anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, quinoline metal complex, tris (8-hydroxyxyl) Norinato) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8-quinolinato) aluminum complex, aminoquinoline metal complex, benzoquinoline metal complex, tri- (p-terphenyl- 4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran, quinacridone, rubrene, distyrylbenzene derivative, distyrylarylene derivative, distili And amine derivatives, and various fluorescent pigments, but include those including a material system and its derivatives described above, not limited to these. In addition, it is also preferable to use a mixture of light emitting materials selected from these compounds as appropriate. Further, not only a compound that emits fluorescence, typified by the above compound, but also a material system that emits light from a spin multiplet, for example, a phosphorescent material that emits phosphorescence, and a part thereof are included in a part of the molecule. A compound can also be used suitably. The light emitting layer made of these materials may be formed by a dry process such as vapor deposition or transfer, or by a wet process such as spin coating, spray coating, die coating, or gravure printing. You may do.

  The material used for the hole injection layer can be formed using a hole injection organic material, a metal oxide, a so-called acceptor organic material or inorganic material, a p-doped layer, or the like. Examples of the hole-injecting organic material include a material having hole transportability, a work function of about 5.0 to 6.0 eV, and exhibiting strong adhesion to the anode 12. Examples thereof include CuPc and starburst amine. The hole-injecting metal oxide is a metal oxide containing any of molybdenum, rhenium, tungsten, vanadium, zinc, indium, tin, gallium, titanium, and aluminum, for example. In addition, an oxide of a plurality of metals containing any one of the above metals, such as indium and tin, indium and zinc, aluminum and gallium, gallium and zinc, titanium and niobium, etc. It may be. The hole injection layer made of these materials may be formed by a dry process such as vapor deposition or transfer, or by a wet process such as spin coating, spray coating, die coating, or gravure printing. It may be a film.

  The material used for the hole transport layer can be selected from, for example, a group of compounds having hole transport properties. Examples of this type of compound include 4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD), 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, arylamine compounds, amine compounds containing a carbazole group, An amine compound containing a fluorene derivative can be exemplified, and any generally known hole transporting material can be used.

The material used 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 transporting materials such as Alq ₃ and compounds having a heterocyclic ring such as phenanthroline derivatives, pyridine derivatives, tetrazine derivatives, and oxadiazole derivatives. Instead, any generally known electron transport material can be used.

The material of the electron injection layer is, for example, a metal fluoride such as lithium fluoride or magnesium fluoride, a metal halide such as sodium chloride or magnesium chloride, aluminum, cobalt, zirconium, Titanium, vanadium, niobium, chromium, tantalum, tungsten, manganese, molybdenum, ruthenium, iron, nickel, copper, gallium, zinc, silicon oxides, nitrides, carbides, oxynitrides, etc., for example, oxidation Any insulating material such as aluminum, magnesium oxide, iron oxide, aluminum nitride, silicon nitride, silicon carbide, silicon oxynitride, boron nitride, silicon compounds including SiO ₂ and SiO, carbon compounds, etc. It can be selected and used. These materials can be formed into a thin film by being formed by a vacuum deposition method or a sputtering method.

  As a plastic material of the plastic film 10, polyethylene terephthalate (PET) is adopted, but not limited to PET, for example, polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), etc. It may be adopted and may be appropriately selected according to the desired application, refractive index, heat-resistant temperature, and the like. PET is a very inexpensive and highly safe plastic material. PEN has a higher refractive index and better heat resistance than PET, but is expensive.

  The plastic film 10 described above is less expensive than an inexpensive glass substrate such as an alkali-free glass substrate or a soda lime glass substrate, has a refractive index larger than that of the glass substrate, and the light emitting layer and anode of the organic EL element 11. The refractive index difference from 12 can be reduced. Therefore, the light extraction efficiency of the organic EL element unit 1 can be improved as compared with the case where the organic EL element 11 is formed on one surface side of the glass substrate and light is extracted from the other surface side of the glass substrate.

  In addition, it is conceivable to form the organic EL element 11 on a glass substrate instead of the plastic film 10, but when the organic EL element 11 is formed on the glass substrate, the surface on which the organic EL element 11 is formed on the glass substrate. Therefore, it is necessary to prepare a glass substrate for forming an element that is polished with high accuracy so that the surface roughness of the substrate becomes small, and the cost increases. In addition, about the surface roughness of the said one surface of the plastic film 10, it is preferable to make arithmetic mean roughness Ra prescribed | regulated by JISB0601-2001 (ISO 4287-1997) below several nm. In this case, the plastic film 10 can be obtained at low cost with an arithmetic average roughness Ra of one nanometer or less on the one surface without performing particularly high-precision polishing.

  The plastic film 10 has a rectangular shape in plan view. In the organic EL element unit 1, a wiring layer 15 (hereinafter referred to as a first wiring layer 15) electrically connected to the anode 12 is formed on the one surface side of the plastic film 10, and a cathode A wiring layer 17 (hereinafter referred to as a second wiring layer 17) electrically connected to 14 is formed. In addition, although the planar view shape of the plastic film 10 is made into the rectangular shape, it is not restricted to this, For example, circular shape, triangular shape, pentagon shape, hexagonal shape, etc. may be sufficient. Further, the numbers and shapes of the first wiring layer 15 and the second wiring layer 17 are not particularly limited, and the number may be singular or plural.

  In the organic EL element unit 1, the first wiring layer 15 is made of the same material as that of the anode 12, and the first wiring layer 15 is formed simultaneously with the anode 12. Therefore, compared with the case of forming different materials separately, the manufacturing process can be simplified and the cost can be reduced by reducing the material cost. The material of the second wiring layer 17 is the same as that of the cathode 14, and the second wiring layer 17 is formed simultaneously with the cathode 14. Therefore, compared with the case of forming different materials separately, the manufacturing process can be simplified and the cost can be reduced by reducing the material cost. The wiring layers 15 and 17 are not limited to a single layer structure, and may have a multilayer structure.

  The first cover substrate 2 uses, for example, a non-alkali glass substrate as the first glass substrate, but is not limited thereto, and for example, a blue soda glass substrate may be used.

  The first cover substrate 2 has an external connection electrode 25 (hereinafter referred to as a first external connection electrode 25) associated with the first wiring layer 15 and a second wiring layer on the one surface side. The external connection electrode 27 (hereinafter referred to as the second external connection electrode 27) corresponding to 17 is formed of the same material and with the same thickness.

  The first cover substrate 2 has a rectangular shape in plan view. However, the shape is not limited to the rectangular shape, and the first cover substrate 2 may be appropriately changed according to the planar shape of the organic EL element unit 1. A shape, a triangular shape, a pentagonal shape, a hexagonal shape or the like may be used.

  The planar size of the first cover substrate 2 is set to be larger than the planar size of the organic EL element unit 1, and each of the external connection electrodes 25 and 27 is located inside the projection area of the sealing portion 5 and is an organic EL element. The unit 1 is positioned within the projection area. Here, the first external connection electrode 25 is formed in the projection region of the first wiring layer 15, but it is sufficient that at least a part thereof is formed in the projection region of the first wiring layer 15. . Further, the second external connection electrode 27 is formed in the projection area of the second wiring layer 17, but it is sufficient that at least a part thereof is formed in the projection area of the second wiring layer 17. The external connection electrodes 25 and 27 are preferably formed by a dry process such as sputtering or vapor deposition. In addition, although the planar view shape of each external connection electrode 25 and 27 is made into square shape, these planar view shapes are not specifically limited, For example, circular shape may be sufficient.

  The spacer portion 4 is preferably formed in a frame shape along the outer peripheral portion of the plastic film 10, and in this embodiment, it is formed in a rectangular frame shape. The spacer portion 4 is made of, for example, an adhesive film, a thermosetting resin, an ultraviolet curable resin, an adhesive (for example, an epoxy resin, an acrylic resin, a silicone resin, or the like), and the plastic film 10 and the first cover substrate. 2 can be used as a joint portion. The spacer portion 4 may be separately formed from a plastic film, a glass substrate, or the like, and bonded to the plastic film 10 and the first cover substrate 2. Further, the spacer portion 4 may be formed integrally with the first cover substrate 2.

  The second cover substrate 3 uses, for example, a non-alkali glass substrate as the second glass substrate, but is not limited thereto, and for example, a blue soda glass substrate may be used. However, the second cover substrate 3 is preferably formed of a material having the same thermal expansion coefficient as that of the first cover substrate 2.

  The second cover substrate 3 has a rectangular shape in plan view. However, the shape is not limited to the rectangular shape, and is not limited thereto. For example, the second cover substrate 3 is appropriately selected according to the planar shape of the organic EL element unit 1 or the first cover substrate 2. It may be changed, and may be circular, triangular, pentagonal, hexagonal or the like.

  In addition, although the plane size of the second cover substrate 3 is set slightly smaller than the plane size of the first cover substrate 2, it may be the same plane size as the first cover substrate 2. In this case, The light emitting device can be further downsized.

  The sealing part 5 is formed using frit glass. Here, when manufacturing the light emitting device, a molded product of frit glass serving as a basis of the sealing portion 5 is disposed on the first cover substrate 2, and the frit is formed between the second cover substrate 3 and the first cover substrate 2. After sandwiching the glass molded product, the molded product may be heated with a laser beam or the like and bonded to the first cover substrate 2 and the second cover substrate 3 respectively. In this case, an appropriate impurity may be added to the frit glass so that the frit glass is easily heated by the laser beam. In addition, you may perform a heating not only with a laser beam but with infrared rays, for example.

  The sealing portion 5 is not limited to being formed using only frit glass. For example, the frame member made of an alloy and the opposing surfaces of the first cover substrate 2 and the second cover substrate 3 in the frame member, respectively. You may form using the frit glass formed in this. Here, as an alloy that is a material of the frame member, Kovar having a thermal expansion coefficient close to that of the first cover substrate 2 and the second cover substrate 3 is preferably used, but is not limited to Kovar. Instead, for example, 42 alloy may be used. Kovar is an alloy in which nickel and cobalt are blended with iron and has a low coefficient of thermal expansion near normal temperatures. Among these metals, the coefficient of thermal expansion of alkali-free glass, blue soda glass, borosilicate glass, etc. It has a value close to. An example of the component ratio of Kovar is wt%, nickel: 29 wt%, cobalt: 17 wt%, silicon: 0.2 wt%, manganese: 0.3 wt%, iron: 53.5 wt%. The component ratio of Kovar is not particularly limited, and a component having an appropriate component ratio may be employed so that the coefficient of thermal expansion of Kovar matches that of the first cover substrate 2 and the second cover substrate 3. Good. In addition, as the frit glass in this case, it is preferable to employ a material capable of aligning the thermal expansion coefficient with the thermal expansion coefficient of the alloy. Here, when the alloy is Kovar, it is preferable to use Kovar glass as the material of the frit glass. Further, in forming the member that is the basis of the sealing portion 5, for example, frit glass is formed on both surfaces in the thickness direction of a plate material made of an alloy such as Kovar with a predetermined pattern (in this embodiment, a rectangular frame pattern). The member which becomes the foundation of the sealing part 5 can be formed by performing press-punching after coating and drying and firing.

  As can be seen from the above description, in this embodiment, the linear expansion coefficients of the first cover substrate 2, the second cover substrate 3, and the sealing portion 5 are aligned. Here, to make the thermal expansion coefficients uniform is not limited to completely matching, but means that they are substantially the same, and the purpose is to select materials so that the difference in thermal expansion coefficients is as small as possible.

  By the way, as described above, in the light emitting device of this embodiment, the organic EL element unit 1 includes the concavo-convex structure portion 19, and the space 6 exists between the concavo-convex structure portion 19 and the first cover substrate 2. . Therefore, it is possible to reduce the reflection loss of the light emitted from the light emitting layer of the organic EL element 11 and reach the first cover substrate 2, and the light extraction efficiency can be improved. The atmosphere in the space 6 is preferably an inert gas.

  Here, the refractive index of each of the light emitting layer of the organic EL element 11 and the plastic film 10 is larger than the refractive index of air or an inert gas which is an external atmosphere from which light is extracted. Therefore, when the above-described concavo-convex structure portion 19 is not provided and the atmosphere of the space 6 between the plastic film 10 and the first cover substrate 2 is air or an inert gas, the plastic film 10 is used. Total reflection occurs at the interface between the first medium and the second medium made of air or inert gas, and light incident on the interface is reflected at an angle greater than the total reflection angle. Then, the light reflected at the interface between the first medium and the second medium is reflected multiple times inside the organic EL layer 13 or the plastic film 10 and attenuates without being extracted outside, so that the light extraction efficiency is lowered. Also, light extraction efficiency is further reduced because Fresnel reflection occurs for light incident on the interface between the first medium and the second medium at an angle less than the total reflection angle.

  On the other hand, in this embodiment, since the uneven | corrugated structure part 19 is provided in the said other surface side of the plastic film 10, the light extraction efficiency to the exterior of the organic EL element unit 1 can be improved.

  The concavo-convex structure portion 19 has a two-dimensional periodic structure in which a large number of protrusions 19 a are periodically arranged in a two-dimensional plane parallel to the one surface of the plastic film 10. In the example shown in FIG. 1, the protrusion 19 a has a quadrangular pyramid shape, but the shape of the protrusion 19 a may be a cone other than the quadrangular pyramid (for example, a triangular pyramid, a hexagonal pyramid, a cone, etc.). However, it may be hemispherical or other shapes.

  Here, the period P of the two-dimensional periodic structure indicates that the wavelength in the medium is λ (the wavelength in vacuum is divided by the refractive index of the medium when the wavelength of light emitted from the light emitting layer is in the range of 300 to 800 nm. Value), it is desirable to set appropriately within a range of 1/4 to 10 times the wavelength λ.

  When the period P is set in the range of 5λ to 10λ, for example, the light extraction efficiency is improved by the geometrical optical effect, that is, the area of the surface where the incident angle is less than the total reflection angle. Further, when the period P is set in a range of λ to 5λ, for example, the light extraction efficiency is improved by the action of extracting light having a total reflection angle or more by diffracted light. In addition, when the period P is set in the range of λ / 4 to λ, the effective refractive index near the concavo-convex structure portion 19 gradually decreases as the distance from the one surface of the plastic film 10 increases. It is equivalent to interposing a thin film layer having a refractive index intermediate between the refractive index of the medium of the concavo-convex structure portion 19 and the refractive index of the medium of the space 6 between the plastic film 10 and the space 70, and reduces Fresnel reflection. It becomes possible to make it. In short, if the period P is set in the range of λ / 4 to 10λ, reflection (total reflection or Fresnel reflection) can be suppressed, and the light extraction efficiency of the organic EL element unit 1 is improved. However, the upper limit of the period P for improving the light extraction efficiency by the geometric optical effect is applicable up to 1000λ. In addition, the concavo-convex structure portion 19 does not necessarily have a periodic structure such as a two-dimensional periodic structure, and the light extraction efficiency can be improved even in a concavo-convex structure having a random concavo-convex size or a concavo-convex structure having no periodicity. When uneven structures of different sizes coexist (for example, when an uneven structure with a period P of 1λ and an uneven structure of 5λ or more coexist), the unevenness with the largest occupation ratio in the uneven structure portion 19 among them. The light extraction effect of the structure becomes dominant.

  The concavo-convex structure portion 19 is configured by a prism sheet (for example, a light diffusion film such as LIGHTUP (registered trademark) GM3 manufactured by Kimoto Co., Ltd.), but is not limited thereto. For example, the uneven structure portion 19 may be formed on the other surface of the plastic film 10 by an imprint method (nanoimprint method). The imprinting method is not limited to the thermal imprinting method (thermal nanoimprinting method), and an optical imprinting method (optical nanoimprinting method) may be employed.

  For the concavo-convex structure portion 19, a hard coat for preventing the surface from being scratched is applied, or a prism sheet having a sufficiently high hardness is used, or a transparent material having a sufficiently high hardness after curing is used. It is desirable to use it. As a hard coat agent for applying a hard coat, for example, TYZ series manufactured by Toyo Ink ([searched on December 22, 2009], Internet <URL: http://www.toyoink.co.jp/products/ lioduras / index.html>) and other high refractive index type (refractive index of about 1.63 to 1.74) hard coating agents can be employed. The TYZ series is an ultraviolet curable hard coat agent in which zirconia is mixed as a filler in an epoxy resin or the like.

  In the light emitting device of the present embodiment, it is important that the space 6 exists between the surface of the uneven structure portion 19 and the first cover substrate 2. If the entire surface of the concavo-convex structure portion 19 is the interface between the concavo-convex structure portion 19 and the first cover substrate 2, there is a refractive index interface between the first cover substrate 2 and external air. Therefore, total reflection occurs again at the refractive index interface. On the other hand, in this embodiment, since the light of the organic EL element 11 can be once extracted into the space 6, the interface between the inert gas in the space 6 and the first cover substrate 2, the first cover substrate. No total reflection loss occurs at the interface between the air 2 and external air.

  Moreover, as a material of the above-mentioned penetration wirings 85 and 87, copper, gold | metal | money, nickel, a conductive paste etc. should just be employ | adopted, for example. Further, as the material of the external connection electrodes 25 and 27, for example, gold may be adopted. The external connection electrodes 25 and 27 are not limited to a single layer structure, and may have a multilayer structure.

  Here, in the light emitting device of the present embodiment, for example, a plastic film 10 in which a plurality of vias (conductor portions) that can constitute a part of each of the through wirings 85 and 87 is formed in advance is used. That's fine. In this case, in manufacturing the light emitting device, first, the organic EL element unit including the organic EL element 11 is formed by sequentially forming the anode 12, the organic EL layer 13, and the cathode 14 on the one surface side of the plastic film 10. 1 and the anode 12 and the cathode 14 are electrically connected to different vias of the plastic film 10, respectively. On the other hand, a structure composed of the first glass substrate that is the source of the first cover substrate 2 and the spacer portion 4 (even if the spacer portion 4 is formed integrally with the first glass substrate, 1 may be fixed to one glass substrate), and through-holes are formed in the portions corresponding to the through-wirings 85 and 87, respectively. Then, the through holes of the structure constituted by the first glass substrate and the spacer portion 4 and the vias of the organic EL element unit 1 are aligned to align the plastic film 10 and the spacer portion 4 of the organic EL element unit 1. And fix. After that, by burying the metal portions constituting the through wires 85 and 87 together with the vias in the respective through holes by plating, the through wires 85 and 87 are formed, and then the external connection electrodes 25 and 27 are formed. Thus, the first cover substrate 2 is completed. Then, the first cover substrate 2 and the second cover substrate 3 may be joined via the sealing portion 5.

  Further, the light emitting device of the present embodiment is sealed in a space surrounded by the organic EL element unit 1, the second cover substrate 3 and the sealing portion 6 and made of a liquid having a higher thermal conductivity than an inert gas. A stopping medium (for example, silicone oil, paraffin oil, etc.) 7 is enclosed. Therefore, it is possible to more reliably prevent moisture and gas from reaching the organic EL element 11 from the outside, and the reliability is improved. In order to enclose the medium 7, the second cover substrate 3 is formed with an injection hole (not shown) for the medium 7 and an air vent hole (not shown). The injection hole and the air vent hole may be sealed with an adhesive after the medium 7 is sealed in the space.

  Here, in the light emitting device of this embodiment, the peripheral portion and the side edge of the plastic film 11 are covered with a covering portion (not shown) made of a sealing material (for example, silicone resin) over the entire periphery. For example, the medium 7 can be prevented from leaking into the space 6 between the plastic film 11 and the first cover substrate 2. Note that the medium 7 is not necessarily sealed in the space surrounded by the organic EL element unit 1, the second cover substrate 3, and the sealing portion 6, and the space may be an inert gas atmosphere or a vacuum atmosphere. . In this case, of course, the above-described injection hole and air vent hole are not necessary.

  In the light emitting device of the present embodiment described above, the first cover substrate 2 formed using the first glass substrate and disposed on the other surface side of the plastic film 10 in the organic EL element unit 1, and the second A second glass substrate is formed by using a glass substrate and is airtightly bonded to the first cover substrate 2 by frit glass so as to cover the organic EL device unit 1 and is disposed on the organic EL device 11 side of the organic EL device unit 1. Since the cover substrate 3 is provided, the moisture resistance can be improved and the life can be further extended.

  In addition, the light emitting device of this embodiment includes a frame-shaped spacer portion 4 interposed between the peripheral portion of the organic EL element unit 1 and the first cover substrate 2, and the organic EL element unit 1 is a plastic film 10. Provided with the concavo-convex structure portion 19 which is provided on the other surface side and suppresses reflection of light emitted from the organic EL element 11 on the other surface, and between the surface of the concavo-convex structure portion 19 and the first cover substrate 2. Therefore, the reflection loss of the light emitted from the light emitting layer of the organic EL element 11 and reaching the package substrate 50 can be reduced, and the light extraction efficiency can be improved.

  In addition, the light emitting device of this embodiment includes a plurality of external connections electrically connected to the wiring layers 15 and 17 in the projection region of the organic EL element unit 1 on the one surface side of the first cover substrate 2. The external connection electrodes 25 and 27 and the wiring layers 15 and 17 which have electrodes 25 and 27 and overlap in the thickness direction of the first cover substrate 2 are connected to the first cover substrate 2, the spacer portion 4, and the plastic film 10. Since it is electrically connected through the through wirings 85 and 87 penetrating in the thickness direction of the laminate, an electric wire or the like is connected to the external connection electrodes 25 and 27 from the light extraction surface side of the light emitting device ( External connection) is possible, and the connection of the electric wires becomes easier as compared with the light emitting device described in Patent Document 1. In addition, since the external connection electrodes 15 and 27 are provided in the projection area of the organic EL element unit 1, the light emitting device can be reduced in size compared to the case where the external connection electrodes 15 and 27 are located outside the projection area. The area of the non-light emitting portion on one surface can be reduced.

  Thus, in the light emitting device of this embodiment, external connection from the light extraction surface side is easy, and the lifetime can be further extended while suppressing a decrease in light extraction efficiency.

  Further, in the light emitting device of the present embodiment, a medium for sealing the organic EL element 11 made of a liquid having higher thermal conductivity than the inert gas between the organic EL element unit 1 and the second cover substrate 3. 7 is interposed, it is possible to efficiently dissipate the heat generated in the organic EL element 11 through the medium 7, so that a rise in temperature of the organic EL element 11 can be suppressed and a long lifetime can be achieved. In addition, the current flowing to the organic EL element 11 can be increased to increase the luminance. Further, in the light emitting device of the present embodiment, through wirings 85 and 87 for feeding power to the organic EL element 11 are formed on the first cover substrate 2 side, and the organic EL element is formed on the second cover substrate 3. 11 is not formed, Joule heat generated in the through wirings 85 and 87 when power is supplied to the organic EL element 11 does not directly affect the second cover substrate 3, and the organic EL element 11 and the second Since the temperature difference from the cover substrate 3 can be increased, the heat generated in the organic EL element 11 can be radiated more efficiently.

By the way, in the light emitting device of the present embodiment, when light emitted from the organic EL element 11 passes through the first cover substrate 2, a loss due to Fresnel reflection (Fresnel loss) occurs. Therefore, in the light emitting device of this embodiment, it is desirable to reduce the Fresnel loss when light passes through the first cover substrate 2. As a means for suppressing the Fresnel loss, for example, an anti-reflection coat (hereinafter referred to as AR) made of a single-layer or multilayer dielectric film on at least one of the one surface and the other surface of the first cover substrate 2. It is conceivable to provide an abbreviated film). Here, when the AR film is formed of, for example, a magnesium fluoride film having a refractive index n of 1.38, if the design wavelength λ ₀ is 550 nm, the thickness of the AR film is λ ₀ / 4n = 550 / ( 4 × 1.38) = 99.6 nm. Similarly, when the AR film is composed of, for example, an aluminum oxide film having a refractive index n of 1.58, if the design wavelength λ ₀ is 550 nm, the thickness of the AR film is λ ₀ / 4n = 550 / (4 × 1.58) = 87.0 nm. The AR film may be a stacked film (two-layer AR film) of a magnesium fluoride film having a thickness of 99.6 nm and an aluminum oxide film having a thickness of 87.0 nm. Note that a material other than magnesium fluoride or aluminum oxide may be adopted as the material of the dielectric film.

  In the light emitting device of the present embodiment, by providing an AR film on at least one of the one surface and the other surface of the first cover substrate 2, preferably both, the Fresnel loss can be reduced and the light extraction efficiency can be improved.

  As another means for suppressing the Fresnel loss, it is conceivable to provide a moth-eye structure on at least one of the one surface and the other surface of the first cover substrate 2. The moth-eye structure has a two-dimensional periodic structure in which tapered fine protrusions are arranged in a two-dimensional array, and a medium (for example, air, inert gas) that enters between the fine protrusions adjacent to many fine protrusions. ) And an anti-reflection part. Here, when the moth-eye structure is formed by processing the first cover substrate 2 by the nanoimprint method, the refractive index of the fine protrusions is the same as the refractive index of the first cover substrate 2. In this case, the effective refractive index of the antireflection portion is continuous between the refractive index (= 1.51) of the second cover substrate 2 and the refractive index of the medium (= 1) in the thickness direction of the antireflection portion. Thus, a state in which the refractive index interface causing the Fresnel loss is eliminated can be obtained in a pseudo manner. Therefore, in the moth-eye structure, the dependency on the wavelength and the incident angle can be reduced and the reflectance can be reduced as compared with the AR film.

  The height of the fine protrusions and the period of the fine protrusions in the moth-eye structure may be set to, for example, 200 nm and 100 nm, respectively, but these numerical values are examples and are not particularly limited.

  The moth-eye structure described above can be formed by, for example, a nanoimprint method, but may be formed by a method other than the nanoprint method (for example, laser processing technology). Further, the moth-eye structure may be constituted by, for example, a moth-eye type non-reflective film manufactured by Mitsubishi Rayon Co., Ltd.

(Embodiment 2)
The basic configuration of the light emitting device of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIG. 2, the peripheral portions of the first cover substrate 2 and the second cover substrate 3 are in contact with each other. A seal made of frit glass formed across the outer peripheral edge 2a of the first cover substrate 2 and the outer peripheral edge 3a of the second cover substrate 3 and sealing the boundary between the outer peripheral edges 2a and 3a over the entire periphery. The difference is that the first cover substrate 2 and the second cover substrate 3 are hermetically joined by the stopper 5. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In the light emitting device of the present embodiment, the peripheral portions of the first cover substrate 2 and the second cover substrate 3 are in contact with each other, so that the organic EL element 11 and the second cover in the thickness direction of the organic EL element 1 are in contact. The accuracy of the distance to the substrate 3 can be increased, and variations in heat dissipation characteristics for each product can be reduced. In the present embodiment, the outer peripheral edge 2a of the first cover substrate 2 and the outer peripheral edge 3a of the second cover substrate 3 are formed so as to seal the boundary between the outer peripheral edges 2a and 3a over the entire periphery. Since the first cover substrate 2 and the second cover substrate 3 are hermetically joined by the sealing portion 5 made of the stopped frit glass, the first cover substrate 2 and the second cover substrate 2 are connected to each other as in the first embodiment. Compared with the case where the peripheral portions of the cover substrate 3 are joined by the sealing portion 5, the width of the sealing portion 5 in a plan view can be narrowed, and the package can be downsized.

DESCRIPTION OF SYMBOLS 1 Organic EL element unit 2 1st cover board | substrate 2a Outer periphery 3 2nd cover substrate 3a Outer periphery 4 Spacer part 5 Sealing part 6 Space 7 Medium 10 Plastic film 11 Organic EL element 12 Anode (electrode)
13 Organic EL layer 14 Cathode (electrode)
DESCRIPTION OF SYMBOLS 15 Wiring layer 17 Wiring layer 19 Uneven structure part 25 External connection electrode 27 External connection electrode 85 Through wiring 87 Through wiring

Claims (3)

  An organic EL element having a light emitting layer between a pair of electrodes spaced in the thickness direction and an organic layer in which a wiring layer electrically connected to each electrode of the organic EL element is formed on one surface side of a transparent plastic film Formed using an EL element unit, a first cover substrate formed using the first glass substrate and disposed on the other surface side of the plastic film in the organic EL element unit, and a second glass substrate A second cover substrate disposed on the organic EL element side of the organic EL element unit and hermetically bonded to the first cover substrate by frit glass so as to cover the organic EL element unit, and the organic EL A frame-shaped spacer portion interposed between a peripheral portion of the element unit and the first cover substrate, wherein the organic EL element unit is A concavo-convex structure portion that is provided on the other surface side of the film and suppresses reflection of light emitted from the organic EL element on the other surface, and between the surface of the concavo-convex structure portion and the first cover substrate. And the first cover substrate is electrically connected to each of the wiring layers in the projection area of the organic EL element unit on the one surface side opposite to the organic EL element unit side. The external connection electrode having a plurality of external connection electrodes and overlapping in the thickness direction of the first cover substrate and the wiring layer are formed of a laminate of the first cover substrate, the spacer portion, and the plastic film. A light emitting device characterized in that it is electrically connected through a through wiring penetrating in the thickness direction.   The peripheral portions of the first cover substrate and the second cover substrate are in contact with each other, and are formed across the outer peripheral edge of the first cover substrate and the outer peripheral edge of the second cover substrate. The first cover substrate and the second cover substrate are hermetically bonded by a sealing portion made of the frit glass in which the boundary between both outer peripheral edges is sealed over the entire circumference. The light-emitting device according to claim 1.   A medium made of a liquid having a higher thermal conductivity than an inert gas is interposed between the organic EL element unit and the second cover substrate, and the medium seals the organic EL element. The light emitting device according to claim 1.

Images