JP2013077388A - Organic electroluminescence device and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescence device and a manufacturing method therefor, capable of improving luminous efficiency by print forming an ink having a dissolved organic luminescent medium material on a pixel region sectioned by a barrier, and by forming an organic luminescent medium layer flat in the pixel region.SOLUTION: An organic electroluminescence device 10 includes: a substrate 11; grid-shaped barriers 13, 13' disposed on the substrate 11; a first electrode 12 formed in a region sectioned by the grid-shaped barriers 13, 13'; an organic luminescent medium layer 15 including an organic luminescent material and formed on the first electrode 12; and a second electrode 16 formed on the organic luminescent medium layer 15. A flattened barrier 14 is formed in the center portion of the region, sectioned by the grid-shaped barriers 13, 13', on the first electrode 12.

Description

  The present invention relates to an organic electroluminescence element formed by a printing method and its production.

  In recent years, large and small optical display devices have been used for display applications of information display terminals. Among them, a display device using an organic electroluminescence element (hereinafter also referred to as “organic EL element”) is a self-luminous type, and thus has a high response speed and low power consumption. ing. The organic EL element has a simple basic structure in which a light emitting medium layer containing an organic light emitting material is sandwiched between a first electrode and a second electrode. A voltage is applied between the electrodes, and the light generated when the holes injected from one electrode and the electrons injected from the other electrode recombine in the light emitting layer is used as an image display or light source. is there.

  The organic EL element generally uses a method of forming a low molecular light emitting medium material by a vapor deposition method. However, there is a problem that an expensive vapor deposition apparatus is required as many as the number of low molecular light emitting medium layers stacked. With the refinement, there is a problem that it is difficult to increase the size of the substrate. As means for solving these problems, an organic light emitting medium is produced by dissolving a low molecular light emitting medium material or a polymer light emitting medium material in an organic solvent to form an ink, and using a printing method such as an inkjet method, a relief printing method, or a nozzle coating method. There is a method of forming a layer (see Patent Document 1).

  An organic EL element using a printing method can print and form a uniform amount of ink on a high-definition pixel even on a large substrate. However, the phenomenon that the ink wets the partition walls that partition the pixel area occurs. It is difficult to flatten the organic light emitting medium layer, the light emission shape tends to be a circle (or an ellipse), and there is a problem that the light emission efficiency decreases and the chromaticity decreases. In order to solve this problem, a method of making the partition walls water-repellent has been reported (see Patent Document 2), but the problem that the effect cannot be obtained when a plurality of organic light emitting medium layers are laminated, There is a problem that film peeling occurs due to a decrease in adhesion of the second electrode.

JP 2002-31561 A JP 2011-96375 A

  The present invention has been made in view of the above problems, and prints ink in which an organic light emitting medium material is dissolved in a pixel region partitioned by a partition, and forms an organic light emitting medium layer flatly in the pixel region. Thus, an object of the present invention is to provide an organic electroluminescence element capable of improving luminous efficiency and a method for manufacturing the same.

  One embodiment of the present invention made to solve the above problems is a substrate, a grid-like partition provided on the substrate, a first electrode formed in a region partitioned by the grid-like partition, In an organic electroluminescent element having an organic light emitting medium layer containing an organic light emitting material formed on the first electrode and a second electrode formed on the organic light emitting medium layer, the organic electroluminescent element is partitioned by the lattice-shaped partition walls. An organic electroluminescence element characterized in that a flattened partition wall is formed on the first electrode at the center in the region.

In another aspect of the present invention, the height of the flattened partition wall may be in the range of 60% or more and 80% or less of the height of the grid-shaped partition wall.
In another aspect of the present invention, the flattened partition wall may be transparent.
In another embodiment of the present invention, the flattened partition wall may have a width of 10 μm or less.

According to another aspect of the present invention, at least one of the planarizations is performed so that distances from four sides of the grid-shaped partition walls to the planarization partition walls are uniform in a region partitioned by the grid-shaped partition walls. A partition wall may be formed.
In another aspect of the present invention, the lattice-shaped partition may have a two-stage configuration including a first-stage partition and a second-stage partition formed on the first-stage partition. .
In another aspect of the present invention, the second-stage partition of the lattice-shaped partition is formed of the same material as the planarized partition, and the second-stage partition of the lattice-shaped partition and the flat The barrier ribs may be formed at the same time.
In another aspect of the present invention, the first-stage partition wall of the lattice-shaped partition wall may have a lattice shape, and the second-stage partition wall of the lattice-shaped partition wall may be a line-shaped partition wall. .
In another aspect of the present invention, the planarization partition may be covered with the second electrode.

Further, another aspect of the present invention is defined by a step of forming a first electrode on a substrate, a step of forming a grid-like partition so as to cover an end of the first electrode, and the grid-like partition A step of forming a flattened partition wall at a central portion in the region and a printing method using a line-shaped relief plate having a convex portion, on the first electrode in the region partitioned by the grid-shaped partition wall and the flattened partition wall A method for manufacturing an organic electroluminescent element, comprising: forming an organic light emitting medium layer thereon; and forming a second electrode on the organic light emitting medium layer, and is used for forming the organic light emitting medium layer The width of the convex portion provided in the line-shaped relief is the same width as the width of the region partitioned by the grid-like partition in the direction parallel to the printing direction, and the line-like relief contacts the flattened partition. Yes, characterized by not It is a manufacturing method of the electroluminescent element.
In another aspect of the present invention, the surface of the lattice-shaped partition walls and the planarized partition walls is subjected to a plasma treatment before the step of forming the organic light emitting medium layer by a printing method using the line-shaped relief printing. A step of cutting within a range of 10 nm or more and 100 nm or less may be included.

  According to the present invention, in an organic EL element using a printing method, an organic light-emitting medium layer can be formed flat in a high-definition pixel region, so that the organic EL element has excellent luminous efficiency and display quality. An EL display can be manufactured on a large substrate at low cost.

It is an example of the cross-sectional structure of the organic electroluminescent element 10 in embodiment of this invention. It is an example of the perspective view of the partition 13 in embodiment of this invention. It is an example of a transfer diagram of the ink 20 to the partition wall 13 without the flattened partition wall 14 using relief printing. In embodiment of this invention, it is an example of a transfer figure of the ink 20 to the partition 13 using relief printing. It is an example of the shape of the planarization partition 14 in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings referred to in the following description are for explaining the configuration of the organic electroluminescence element according to the embodiment of the present invention, and the sizes, thicknesses, dimensions, and the like of the respective parts shown in the drawings are actual. Is different.
As shown in FIGS. 1 to 3, the organic EL element 10 according to the embodiment of the present invention includes a substrate 11, a partition wall 13 (or 13 ′) provided on the substrate 11, and a pixel region partitioned by the partition wall 13. The organic light-emitting medium layer 15 formed therein is provided, and the partition wall 13 is a lattice-shaped partition wall having at least one stage (the two-stage partition walls 13 and 13 'are illustrated). A first electrode 12 is provided below the organic light emitting medium layer 15 and the partition wall 13, and a second electrode 16 is provided above the first electrode 12, so that the organic light emitting medium layer 15 is sandwiched therebetween. In addition, the planarization partition 14, which is a feature of the organic EL element 10 according to the embodiment of the present invention, is formed on the first electrode 12, located substantially in the center of the pixel region defined by the lattice-shaped partition 13. Structure. Although not shown, since the organic light emitting medium layer 15 and the second electrode 16 are easily deteriorated by moisture and oxygen in the atmosphere, a known sealing using a glass material, a barrier film, a barrier film, or the like. Seal and seal by the method. Hereinafter, details of each constituent layer will be described.

<Board>
The board | substrate 11 becomes a support body of the printing body which concerns on embodiment of this invention. As the material of the substrate 11, any substrate can be used as long as it is an insulating material and excellent in dimensional stability. For example, plastic films and sheets such as glass, quartz, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, etc., or oxidation to these plastic films and sheets Metal oxides such as silicon and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride and aluminum nitride, metal oxynitrides such as silicon oxynitride, acrylic resins and epoxy resins Translucent base material with a single layer or laminated polymer resin film such as silicone resin or polyester resin, metal foil such as aluminum or stainless steel, sheet, plate, aluminum on the plastic film or sheet It can be used um, copper, nickel, stainless steel and metal film non-translucent substrate as a laminate of such. What is necessary is just to select the translucency of the base material 11 according to whether it performs from the surface of the board | substrate 11 side or a sealing side as a light extraction surface, and a color is not specifically limited, either. The substrate 11 made of these materials is preferably subjected to moisture-proofing treatment or hydrophobic treatment by forming an inorganic film or a fluororesin layer in order to avoid moisture intrusion into the organic EL element 10. In particular, in order to avoid intrusion of moisture into the organic light emitting medium layer 15, it is preferable to reduce the moisture content and gas permeability coefficient in the substrate 11.

  When the organic EL element 10 is formed, an active drive substrate on which a thin film transistor (hereinafter also referred to as “TFT”) is formed as the substrate 11 may be used. When the printed body according to the embodiment of the present invention is an active drive organic EL element, a planarization layer is formed on the TFT, and the lower electrode (that is, the organic EL element 10) (that is, the planar electrode) The first electrode 12) is provided, and the TFT and the lower electrode are preferably electrically connected via a contact hole provided in the planarization layer. With this configuration, excellent electrical insulation can be obtained between the TFT and the organic EL element 10. The TFT and the organic EL element 10 formed above the TFT are supported by a support. The support is preferably excellent in mechanical strength and dimensional stability. Specifically, the materials described above as the substrate 11 can be used. As the thin film transistor provided on the support, a known thin film transistor can be used. Specifically, a thin film transistor mainly including an active layer in which a source / drain region and a channel region are formed, a gate insulating film, and a gate electrode can be given. The structure of the thin film transistor is not particularly limited, and examples thereof include known structures such as a staggered type, an inverted staggered type, a top gate type, a bottom gate type, and a coplanar type.

The active layer is not particularly limited, and examples thereof include inorganic semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, cadmium selenide, thiophene oligomers, poly (p-ferylene vinylene), and the like. It can be formed of an organic semiconductor material. These active layers are formed by, for example, laminating amorphous silicon by plasma CVD, ion doping; forming amorphous silicon by LPCVD using SiH ₄ gas, and crystallizing amorphous silicon by solid phase growth. After silicon is obtained, ion doping is performed by ion implantation; amorphous silicon is formed by LPCVD using Si ₂ H ₆ gas, or PECVD using SiH ₄ gas, and a laser such as an excimer laser is used. After annealing and crystallizing amorphous silicon to obtain polysilicon, a method of ion doping by ion doping (low temperature process); polysilicon is deposited by low pressure CVD or LPCVD, and thermally oxidized at 1000 ° C. or higher Gate break Film is formed, a gate electrode of the n ⁺ polysilicon is formed thereon, then, a method of ion doping (high temperature process), and the like by an ion implantation method.

As the gate insulating film, a known one used as a gate insulating film can be used. For example, SiO ₂ formed by PECVD method, LPCVD method, etc .; SiO ₂ obtained by thermally oxidizing a polysilicon film Etc. can be used. As a gate electrode, what is normally used as a gate electrode can be used, for example, metals, such as aluminum and copper; refractory metals, such as titanium, tantalum, and tungsten; polysilicon; silicide of refractory metals; Polycide etc. are mentioned. The thin film transistor may have a single gate structure, a double gate structure, or a multi-gate structure having three or more gate electrodes. Moreover, you may have a LDD structure and an offset structure. Further, two or more thin film transistors may be arranged in one pixel.

  In the case where the printed body according to the embodiment of the present invention is formed as the organic EL element 10, the TFT needs to be connected so as to function as a switching element of the organic EL element 10, and the drain electrode of the transistor and the organic EL The pixel electrode (that is, the first electrode 12) of the element 10 is electrically connected. In the case of the top emission structure, the pixel electrode needs to use a metal that reflects light. In the case of the bottom emission structure, the pixel electrode needs to use a material that transmits light. The thin film transistor, the drain electrode, and the pixel electrode of the organic EL element 10 are connected through a connection wiring formed in a contact hole that penetrates the planarization film.

Regarding the material of the planarization film, inorganic materials such as SiO ₂ , spin-on glass, SiN (eg, Si ₃ N ₄ ), TaO (eg, Ta ₂ O ₅ ), polyimide resin, acrylic resin, photoresist material, and black matrix material An organic material such as can be used. A spin coating method, a CVD method, a vapor deposition method, or the like can be selected in accordance with these materials. If necessary, contact holes are formed by dry etching, wet etching, etc. at a position corresponding to the lower layer thin film transistor by photolithography using a photosensitive resin as the planarizing layer, or once the planarizing layer is formed on the entire surface. To do. The contact hole is then filled with a conductive material to establish conduction with the pixel electrode formed in the upper layer of the planarization layer. The thickness of the planarization layer only needs to be able to cover the lower TFT, capacitor, wiring, and the like. The thickness may be several μm, for example, about 3 μm.

<First electrode>
A first electrode 12 is formed on the substrate 11 and patterned as necessary. The first electrode 12 is in the region 130 defined by the grid-like partition wall 13 (or 13 ′) (see FIG. 2), and serves as a pixel electrode corresponding to each pixel. Examples of the material of the first electrode 12 include metal composite oxides such as ITO (indium tin composite oxide), indium zinc composite oxide, and zinc aluminum composite oxide, metal materials such as gold and platinum, and these metal oxides. Alternatively, a single layer or a laminate of fine particle dispersion films in which fine particles of a metal material are dispersed in an epoxy resin or an acrylic resin can be used. When the first electrode 12 is used as an anode, it is preferable to select a material having transparency and conductivity, such as ITO, and having a high work function. In the case of a so-called bottom emission structure in which light is extracted from below, it is necessary to select a light-transmitting material. If necessary, a metal material such as copper or aluminum may be provided as an auxiliary electrode in order to reduce the wiring resistance of the first electrode 12.

  As the formation method of the first electrode 12, depending on the material, dry film forming methods such as resistance heating vapor deposition method, electron beam vapor deposition method, reactive vapor deposition method, ion plating method, sputtering method, gravure printing method, screen A wet film forming method such as a printing method can be used. As a patterning method for the first electrode 12, an existing patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method can be used depending on the material and the film forming method. In the case where a substrate on which a TFT is formed is used as the substrate 11, the substrate 11 is formed so as to be conductive corresponding to the lower pixel.

<Lattice-like partition wall>
The grid-like partition wall 13 according to the embodiment of the present invention is formed so as to partition the light emitting region 132 corresponding to the pixel region 130. When the substrate includes the first electrode 12, it is preferably formed so as to cover the end of the first electrode 12. The partition wall 13 is a grid-shaped partition wall composed of at least one stage, and it is sufficient that the first electrode 12 is partitioned in a grid pattern (see FIG. 2A). As shown in FIG. After providing the lattice-shaped partition wall 13 ′, the line-shaped partition wall 13 may be formed in the second stage. At this time, the convex portions on the relief plate used for printing the organic functional thin film are formed in a straight line parallel to the line-shaped partition walls 13.

  As a method for forming the lattice-shaped partition wall 13, as in the past, an inorganic film is uniformly formed on a substrate, masked with a resist, and then dry etching, or a photosensitive resin is laminated on the substrate, The method of setting it as a predetermined pattern by the photolithography method is mentioned. If necessary, a water repellent can be added, or liquid or liquid repellency can be imparted to the ink 20 after formation by irradiation with plasma or UV.

The preferable height of the partition wall 13 is 0.1 μm to 10 μm. However, if the height is too high, the ink 20 is difficult to be transferred to the pixel region 130 by the relief printing plate 19. In order to prevent color mixing, the thickness is preferably 1 μm or more.
The preferable width of the partition wall 13 is about 3 μm to 50 μm. However, if the width of the partition wall 13 becomes too large, the pixel aperture ratio decreases, and if the width of the partition wall 13 is too small, the formation of a flattened partition wall 14 described later is formed. The area is limited, and it is in contact with the printing plate and causes printing failure.

<Flattened partition wall>
The flattened partition 14 according to the embodiment of the present invention is formed on the first electrode 12 at substantially the center of the pixel region 130 partitioned by the grid-shaped partitions 13. When the flattened partition wall 14 is not formed (see FIG. 3), when the ink 20 is printed and formed in the pixel region 130 by the relief printing method (see FIG. 3A), the ink 20 wets the partition wall 13. In order to rise and dry, the organic light emitting medium layer 15 has a concave film shape. For example, the flattened region 131 having a film thickness difference of 10% or less with respect to the film thickness of the central portion of the organic light emitting medium layer 15 It will be 50% with respect to the area | region 130 (refer FIG.3 (b)). Then, the light emitting region 132 is shaped like an ellipse and becomes about 50% (see FIG. 3C).

  On the other hand, when the grid-like partition substrate having the planarized partition 14 is used (see FIG. 4), when the ink 20 is printed and formed in the pixel region 130 by the relief printing method (FIG. 4A). The ink 20 wets the grid-like partition walls 13, but the level of the flattened partition wall 14 is smaller than that of the grid-like partition wall 13, so that the degree of wetting is small. Since the presence has an effect of reducing the degree of wetting to the lattice-shaped partition wall 13, for example, the planarized region 131 in which the organic light emitting medium layer 15 has a film thickness difference of 10% or less has a corner with respect to the pixel region 130. The light emitting region 132 can be substantially the entire area of the pixel region 130 (see FIG. 4C).

  The shape of the flattening partition wall 14 is illustrated in FIG. 5, but when the distance from the four sides of the grid-shaped partition wall 13 to the flattening partition wall 14 is uniform within the pixel region 130, organic light emission is performed over the entire pixel region 130. Since the medium layer 15 can be planarized, it is preferable. Further, since the portion where the flattened partition 14 is formed cannot emit light, it is meaningless to flatten the organic light emitting medium layer 15 unless the ratio of the flattened partition 14 to the pixel region 130 is reduced. Therefore, it is preferable that the pixel occupation ratio of the planarization partition 14 is at least 30% or less, preferably 15% or less. Furthermore, when a transparent material is used as the material of the planarization partition 14 and the line width of the planarization partition 14 is set to 15 μm or less, preferably 10 μm or less, light emitted from the periphery of the planarization partition 14 is diffused and flattened. The barrier rib 14 is not visible as a black spot. Further, the line width of the flattened partition wall 14 is preferably 3 μm or more. This is because if the line width of the planarization partition 14 is smaller than 3 μm, it cannot be formed by photolithography.

The height of the flattening partition wall 14 has an optimum value depending on the pixel opening width. However, if the height of the planar partitioning wall 13 is approximately 60% to 80% with respect to the height of the lattice-shaped partition wall 13, the planarizing region 131 can be widened, which is preferable. is there. As a method of lowering the flattened partition wall 14 than the lattice-shaped partition wall 13, for example, a photosensitive resin is used as a material for the lattice-shaped partition wall 13 and the flattened partition wall 14. By using a semi-transmissive film for the portion, the exposure (light-shielding) amount with respect to the grid-like partition wall 13 may be changed. In addition, after forming an inorganic film such as silicon nitride as the first-stage lattice-shaped partition wall 13 ′ after forming the second-stage lattice-shaped partition wall 13 as the first-stage lattice-shaped partition wall 13 ′, the planarized partition wall 14 is formed. By forming this, it is possible to easily reduce the height of the first-stage grid-like partition wall 13 '.
In addition, as shown in FIG. 1, a part of this planarization partition 14 may be coat | covered with the 2nd electrode 16 mentioned later. If the flattened partition wall 14 is not covered, it becomes a moisture infiltration path and the organic light emitting layer is deteriorated.

<Organic luminescent medium layer>
Next, the organic light emitting medium layer 15 is formed as an organic functional thin film. The organic light emitting medium layer 15 according to the embodiment of the present invention can be formed of a single layer film or a multilayer film containing an organic light emitting material. Examples of the structure in the case of forming a multilayer film include a hole transport layer, an electron transporting light emitting layer or a hole transporting light emitting layer, a two-layer structure comprising an electron transport layer, a hole transport layer, an organic light emitting layer, and an electron transport. A three-layer structure consisting of layers, and further, by separating a hole or electron injection function and a hole or electron transport function as required, or by inserting a layer that blocks the transport of holes or electrons, etc. More preferably, it is formed. The organic light emitting medium layer 15 does not mean that all the layers are organic materials, but may have at least an organic light emitting layer, and other functional layers may be replaced with inorganic materials. Further, the organic light emitting layer in the present invention refers to a layer containing an organic light emitting material, and the charge transport layer refers to a layer formed to increase other light emitting efficiency such as a hole transport layer.

Examples of the hole transport material used for the hole transport layer include copper phthalocyanine and derivatives thereof, 1,1-bis (4-di-p-triaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-bis ( Low molecular weight materials such as aromatic amines such as 3-methylphenyl) -1,1'-biphenyl-4,4'-diamine, polyaniline derivatives, polythiophene derivatives, polyvinylcarbazole derivatives, poly (3,4-ethylenedioxythiophene) (Hereinafter also referred to as “PEDOT”) and polymer materials such as a mixture of PEDOT and polystyrene sulfonic acid (hereinafter also referred to as “PSS”) (hereinafter also referred to as “PEDOT / PSS”). , polythiophene oligomer _{material, Cu 2 O, Mn 2 O} 3, NiO, Ag 2 O, MoO 2, ZnO, TiO _{Ta 2 O 5, MoO 3,} WO 3, MoO 3 and the like inorganic materials compounds such.

  Organic light-emitting materials used for the organic light-emitting layer include 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolinolato) aluminum complex, tris. (4-methyl-8-quinolinolato) aluminum complex, bis (8-quinolinolato) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolinolato) aluminum complex, tris (4-methyl-5-cyano-) 8-quinolinolato) aluminum complex, bis (2-methyl-5-trifluoromethyl-8-quinolinolato) [4- (4-cyanophenyl) phenolate] aluminum complex, bis (2-methyl-5-cyano-8-quinolinolato) ) [4- (4-Cyanophenyl) phenoler ] Aluminum complex, tris (8-quinolinolato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, poly -2,5-diheptyloxy-para-phenylene vinylene, coumarin phosphor, perylene phosphor, pyran phosphor, anthrone phosphor, porphyrin phosphor, quinacridone phosphor, N, N'-dialkyl Low molecular light emitting materials such as substituted quinacridone phosphors, naphthalimide phosphors, N, N′-diaryl substituted pyrrolopyrrole phosphors, phosphorescent emitters such as Ir complexes, polyfluorenes, polyparaphenylene vinylenes , Polythiophene, polyspiro and other polymer materials The materials and dispersed or copolymerization of low molecular weight material in the material, it is possible to use other existing polymer-low molecular luminescent material.

  As an electron transport material used for the electron transport layer, 2- (4-bifinylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, 2,5-bis (1-naphthyl) ) -1,3,4-oxadiazole, oxadiazole derivatives, bis (10-hydroxybenzo [h] quinolinolato) beryllium complexes, triazole compounds, and the like can be used. For the formation, vacuum deposition or the like can be used.

The film thickness of the organic light-emitting medium layer 15 is 1000 nm or less, preferably 50 nm to 150 nm, even when formed by a single layer or a stacked layer. In particular, the hole transport material of the organic EL element 10 has a large effect of covering the surface protrusions of the substrate and the first electrode 12, and it is more preferable to form a film having a thickness of about 50 nm to 100 nm.
As a method for forming the organic light emitting medium layer 15, the hole transport layer and the electron transport layer are formed by a vacuum deposition method, a spin coating method, a spray coating method, a flexo method, a gravure method, a micro gravure method, a letterpress, depending on the material. Although a printing method, an intaglio offset method, an ink jet method, a nozzle coating method, and the like can be used, a relief printing method is particularly preferable as a method for forming the organic light emitting material layer, and the organic light emitting medium layer 15 is configured in the embodiment of the present invention. At least one of the layers is formed by a relief printing method. The layer formed by the relief printing method is preferably an organic light emitting layer because it needs to be color-coded in accordance with colorization. This method can be preferably applied to the case where the charge transport material is changed in accordance with the characteristics of each color light emitting material. If all the layers constituting the organic light emitting medium layer 15 are formed by the printing method according to the embodiment of the present invention, the manufacturing process can be simplified.

  When the material constituting the organic light emitting medium layer 15 is made into a solution, it is preferable to control the vapor pressure, solid content ratio, viscosity, and the like of the solvent according to the forming method. Solvents include water, xylene, anisole, cyclohexanone, mesitylene, tetralin, cyclohexylbenzene, methyl benzoate, ethyl benzoate, toluene, ethanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, methanol, isopropyl alcohol, ethyl acetate, butyl acetate, etc. These may be a single solvent or a mixed solvent. In order to improve coatability, it is more preferable to mix an appropriate amount of additives such as surfactants, antioxidants, viscosity modifiers and ultraviolet absorbers as necessary. As a method for drying the coating solution, the solvent may be removed to the extent that the light emission characteristics are not hindered, and heating or decompression may be performed.

<Letterpress printing method>
The relief printing method, which is a printing method that can be preferably used in the embodiment of the present invention, will be described in detail. As the relief plate that can be used for forming the organic functional thin film, a water development type resin relief plate is preferably used. Examples of the water-developable photosensitive resin constituting such a resin plate include a type having a hydrophilic polymer and a monomer containing an unsaturated bond, a so-called crosslinkable monomer and a photopolymerization initiator as constituent elements. In this type, polyamide, polyvinyl alcohol, cellulose derivatives and the like are used as hydrophilic polymers. Examples of the crosslinkable monomer include methacrylates having a vinyl bond, and examples of the photopolymerization initiator include aromatic carbonyl compounds. Among these, a polyamide-based water-developable photosensitive resin is preferable from the viewpoint of printability.

  The printing press used to form the organic functional thin film can be any relief printing press that prints on a flat plate as the substrate to be printed. For example, an ink tank, an ink chamber, an anilox roll, and a resin relief printing plate are attached. Has a plate cylinder. The ink tank contains organic functional ink diluted with a solvent, and the organic functional ink is fed into the ink chamber from the ink tank. The anilox roll rotates in contact with the ink supply part of the ink chamber and the plate cylinder.

  With the rotation of the anilox roll, the organic functional ink supplied from the ink chamber is uniformly held on the surface of the anilox roll, and then transferred to the convex portion of the resin relief plate attached to the plate cylinder with a uniform film thickness. Further, the substrate to be printed is fixed on a slidable substrate fixing stage (stage), and moved to the printing start position while adjusting the position by the position adjustment mechanism of the plate pattern and the substrate pattern, and the plate cylinder is rotated. Accordingly, the convex portion of the resin relief printing plate further moves while being in contact with the substrate, and the ink is transferred by patterning to a predetermined position on the substrate.

<Second electrode>
Next, the second electrode 16 is formed. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, LiF, NaF, Ba, BaO or the like is sandwiched about 1 nm at the interface contacting the light emitting medium, so that the stability and conductivity are improved. High Al, Cu, Ag, or the like may be laminated and used. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, Al Alternatively, an alloy system with a metal element such as Cu may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used. In the case of top emission, it is preferable to use a laminated film of the metal layer and a transparent conductive film such as ITO, IZO, or AZO.

  As a method for forming the second electrode 16, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material. Although there is no restriction | limiting in particular in the thickness of the 2nd electrode 16, About 10 nm-about 1000 nm are desirable. Moreover, when using the 2nd electrode 16 as a translucent electrode layer, about 0.1 nm-10 nm are desirable for the film thickness in the case of using metal materials, such as Ca and Li.

<Sealing body>
In the organic EL element 10, since the organic light emitting medium layer 15 and the second electrode 16 are easily deteriorated by moisture and oxygen in the atmosphere, it is necessary to provide a sealing body for shielding from the atmosphere. Although not shown, a known sealing method can be used. For example, it may be sealed with an adhesive layer on the periphery of the sealing glass, a barrier film such as alumina or silicon nitride may be formed, and a barrier film in which SiO _x is formed on both sides of a plastic substrate by a CVD method. It may be covered.
As described above, with the organic electroluminescent element 10 according to the present embodiment, the organic light emitting medium layer 15 can be formed flat in the pixel region 130 by using a printing method, so that the light emission efficiency of the light emitting element is improved. Can be made.
Hereinafter, a method for manufacturing the organic EL element 10 will be briefly described.

<Manufacturing method>
First, the first electrode 12 is formed on the substrate 11. Next, grid-like partition walls 13 and 13 ′ are formed so as to cover the end portion of the first electrode 12. Thereafter, the flattened partition 14 is formed at the center in the pixel region 130 partitioned by the grid-shaped partitions 13 and 13 ′.
Thereafter, the organic light emitting medium layer 15 is formed on the first electrode 12 and the flattened partition wall 14 in the pixel region 130 defined by the grid-shaped partition walls 13 and 13 ′ by a printing method using a line-shaped relief plate having the protrusions 19. Form. Note that the width of the convex portion 19 provided in the line-shaped relief printing used for forming the organic light emitting medium layer 15 is the width of the pixel region 130 defined by the grid-like partition walls 13 and 13 ′ parallel to the printing direction. Is the same width as Further, during printing, the line-shaped relief does not contact the flattened partition wall 14.
Thereafter, the second electrode 16 is formed on the organic light emitting medium layer 15.
The organic EL element 10 can be manufactured through the above steps.
Further, before the step of forming the organic light emitting medium layer 15, a step of performing plasma treatment on the surfaces of the lattice-shaped partition walls 13, 13 ′ and the planarized partition wall 14 and scraping them within a range of 10 nm to 100 nm may be included.

As described above, in the manufacturing method of the organic EL element 10 according to the present embodiment, the ink 20 in which the organic light emitting medium material is dissolved is printed and formed in the pixel region 130 partitioned by the grid-like partition walls 13 and 13 ′. In addition, since the organic light emitting medium layer 15 can be formed flat in the pixel region 130, the light emission efficiency of the light emitting element can be improved.
Next, an embodiment of the present invention will be specifically described, but the present invention is not limited to this.

Example 1
A glass substrate was used as the substrate 11, and an ITO electrode was sputter-formed on the first electrode 12 as a first electrode 12 and then patterned by a photolithographic etching method.
Next, as a grid-like partition wall 13, a film formed by CVD of a silicon nitride film (having a thickness of 0.5 μm) is patterned by dry etching to form a grid-like partition wall 13 ′, and a photosensitive polyimide resin is formed thereon by a slit coating method. Then, a 1.5 μm coating was formed, and a grid-like partition wall 13 was formed by an exposure / development process.

At the same time as forming the grid-like partition wall 13 with photosensitive polyimide resin, the planarization partition wall 14 having a width of 10 μm was formed in a substantially central portion of the pixel region 130 with a thickness of 1.5 μm. At this time, the height ratio of the flattened partition wall 14 to the height of the lattice-shaped partition wall 13 (2.0 μm) was 75%.
Next, printing of the ink 20 is performed a plurality of times using the linear printing plate 19 on the pixel region 130, which is a region partitioned by the lattice-shaped partition wall 13, and the organic light emitting medium layer 15 having a film thickness of 100 nm. Formed. A polyfluorene derivative was used as the organic light emitting material.

Next, 5 nm of Ba and 200 nm of Al were sequentially laminated on the organic light emitting medium layer 15 as a second electrode 16 by vapor deposition, and finally capped.
The organic electroluminescence device 10 completed through the above steps emits light in 95% of the pixel region 130, and the flattened partition wall 14 was not visually recognized as a black spot due to light diffusion, but could be visually recognized as a uniform pixel on the entire surface. . As a result, the same luminance half-life as when the grid-like partition wall 13 was not formed could be achieved. Further, although it was stored for 1000 hours in an environment of 60 ° C. and 90%, a dark area due to the formation of the flattened partition wall 14 did not occur.

(Comparative Example 1)
In Comparative Example 1, an organic EL element was produced without forming the grid-like partition walls 14 in Example 1. As a result, only 50% of the pixel region 130 emitted light. Thereby, the brightness | luminance half life of the organic EL element which concerns on the comparative example 1 became a lifetime about 30% with respect to the brightness | luminance half life when the grid | lattice-like partition 13 was not formed.
(Comparative Example 2)
In Comparative Example 2, the flattened partition 14 having the same height as the lattice-shaped partition wall 13 was formed without forming the lattice-shaped partition wall 13 ′ made of silicon nitride in Example 1. As a result, only 50% of the region between the lattice-shaped partition wall 13 and the flattened partition wall 14 emitted light, so that the flattened partition wall 14 also becomes a non-light emitting region, and the entire pixel region 130 is not illuminated. Only about 40% of the area emitted light. Thereby, the brightness | luminance half life of the organic EL element which concerns on the comparative example 2 became a lifetime of about 10% with respect to the brightness | luminance half life when the grid | lattice-like partition 13 was not formed.

(Comparative Example 3)
In Comparative Example 3, the film thickness of the grid-like partition wall 13 and the flattened partition wall 14 in the second stage is 0.5 μm compared to the film thickness of 0.5 μm of the grid-like partition wall 13 ′ made of silicon nitride in Example 1. The film thickness ratio of the flattened partition wall 14 to the lattice-shaped partition wall 13 (1.0 μm) was 50%. As a result, the effect of suppressing the wetting of the ink 20 onto the grid-like partition wall 13 is thin, and the flattened partition wall 14 was not visually observed as a black spot, but only 50% of the pixel region 130 emitted light, No effect was obtained for the enlargement of the light emitting region 132. As a result, the luminance half life of the organic EL element according to Comparative Example 2 was about 30% of the luminance half life when the lattice-shaped partition wall 13 was not formed.

DESCRIPTION OF SYMBOLS 10 ... Organic EL element 11 ... Board | substrate 12 ... 1st electrode 13 (13 ') ... (grid-like) partition 130 ... Pixel area | region 131 ... Planarization area | region 132 ... Light emission Area 14 ... Flattened partition wall 15 ... Organic light emitting medium layer 16 ... Second electrode 19 ... Convex part 20 ... Ink

Claims (11)

An organic material including a substrate, a grid-like partition provided on the substrate, a first electrode formed in a region partitioned by the grid-like partition, and an organic light-emitting material formed on the first electrode In an organic electroluminescence device having a light emitting medium layer and a second electrode formed on the organic light emitting medium layer,
An organic electroluminescence element, wherein a flattened partition wall is formed on the first electrode at a central portion in a region partitioned by the lattice-shaped partition wall.   2. The organic electroluminescence device according to claim 1, wherein a height of the flattened partition wall is in a range of 60% to 80% of a height of the lattice-shaped partition wall.   The organic electroluminescence element according to claim 1, wherein the planarization partition is transparent.   4. The organic electroluminescence device according to claim 1, wherein the flattened partition wall has a width of 10 μm or less. 5.   In the region partitioned by the grid-shaped partition walls, one or more flattened partition walls are formed so that the distances from the four sides of the grid-shaped partition walls to the planarized partition walls are uniform. The organic electroluminescent element according to any one of claims 1 to 4.   6. The structure according to claim 1, wherein the lattice-shaped partition wall has a two-stage configuration including a first-stage partition wall and a second-stage partition wall formed on the first-stage partition wall. The organic electroluminescent element according to claim 1. The second-stage partition of the lattice-shaped partition is formed of the same material as the planarization partition,
The organic electroluminescence device according to claim 6, wherein the second-stage partition walls and the planarization partition walls of the lattice-shaped partition walls are formed simultaneously. The first-stage partition of the lattice-shaped partition is lattice-shaped,
The organic electroluminescence device according to claim 6 or 7, wherein the second-stage partition walls of the lattice-shaped partition walls are line-shaped partition walls.   The organic electroluminescence device according to any one of claims 1 to 8, wherein the planarization partition is covered with the second electrode. Forming a first electrode on the substrate;
Forming a grid-like partition so as to cover an end of the first electrode;
Forming a flattened partition wall at a central portion in a region defined by the lattice-shaped partition wall;
A step of forming an organic light emitting medium layer on the first electrode and the flattened partition wall in a region defined by the grid-shaped partition wall by a printing method using a line-shaped relief plate having a convex portion;
Forming a second electrode on the organic light emitting medium layer, and a method for producing an organic electroluminescent element comprising:
The width of the convex portion provided on the line-shaped relief printing plate used for forming the organic light emitting medium layer is the same width as the width of the region partitioned by the grid-like partition wall in the direction parallel to the printing direction,
The method of manufacturing an organic electroluminescence element, wherein the line-shaped relief does not contact the planarization partition.   Before the step of forming the organic light emitting medium layer by the printing method using the line-shaped relief printing, the surfaces of the grid-like partition walls and the planarized partition walls are plasma-treated within a range of 10 nm or more and 100 nm or less. The manufacturing method of the organic electroluminescent element of Claim 10 including the process of shaving.

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