JP2011181305A - Organic electroluminescent element and method of manufacturing the same - Google Patents

Abstract

In order to uniformly print and form an organic functional thin film on a substrate to be printed, which is partitioned by a partition, with respect to a printing body on which a thin film is formed by a relief printing method, height variation between the substrate to be printed and the printing plate To provide a method for homogenizing.
A substrate, a grid-shaped first partition and a second partition provided on the substrate, at least a first electrode formed in a region partitioned by the first partition and the second partition, a first An organic electroluminescent device comprising: two electrodes; an organic light emitting medium layer containing at least an organic light emitting material; and a first spacer and a second spacer on the lattice-shaped first partition and the second partition. One spacer is formed on the second partition so that the distance from two adjacent first partitions is equal, and the second spacer is formed on the intersection of the first partition and the second partition. Two organic electroluminescence elements, wherein two are formed so as to be parallel to two partition walls.
[Selection] Figure 1

Description

The present invention relates to a printing body on which a thin film is formed by a printing method, and more particularly to a method for forming a functional organic thin film on a substrate to be printed that has no water absorption and is partitioned by partition walls. In particular, the present invention relates to an organic electroluminescence element (hereinafter, referred to as an organic EL element) that is expected to be used widely as a display such as an information display terminal or a surface light source.

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 EL element has been attracting attention as a next-generation display because it is self-luminous and has a high response speed and low power consumption. The organic EL element has a simple basic structure in which a light emitting 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.

In order to perform some kind of image display with the organic EL element, it is necessary to adjust on / off of light emission for each pixel. For this reason, at least one of the electrodes needs to be patterned in a pixel shape. Usually, the first electrode formed first on the substrate is patterned by etching. At this time, the step at the end of the first electrode provided in a pixel shape on the substrate does not cover the step even if an organic functional thin film such as a hole transport layer or a light emitting layer is formed on the upper layer as it is. In order to cause a short circuit, the end portion of the first electrode is covered with an insulating material. In addition, when the hole transport layer or the light emitting layer formed on the first electrode is formed by a method of discharging ink from a nozzle or a printing method using an organic functional ink in which these materials are dissolved in a solvent. The barrier ribs are formed in order to prevent color mixing and conduction between adjacent pixels. The shape of the partition is in the form of stripes in the case of passive organic EL elements, and in the form of a lattice in the case of active organic EL elements, according to the respective first electrode shapes (Patent Document 1). reference).

Japanese Patent Laid-Open No. 11-810862

When an organic functional thin film is formed by filling the partition wall with organic functional ink by the printing method, the partition wall can be lowered because the ink scatters less than the method of supplying ink from the nozzle. The relief printing method has an advantage that a high-definition pixel can be formed because of excellent patternability. However, in the relief printing method, it is necessary to transfer ink onto the pixels when the convex portions of the plate come into contact with the pixels in the partition wall, so the gap between the substrate and the printing machine, the vibration of the printing machine, and the substrate transport Because the accuracy, the height of the printing plate, the height of the partition, the variation in the amount of ink on the relief plate, the angle at which the relief portion of the relief plate and the pixel contact, the distance between the relief portion and the pixel, etc. vary from pixel to pixel. In addition, the ink on the relief printing plate and the substrate contacted non-uniformly (FIG. 4), resulting in a printing defect such that the amount of ink transferred was different for each pixel and display unevenness occurred on the panel.

The present invention has been made in view of the above problems, and for a printing body in which a thin film is formed by a relief printing method, in order to uniformly print an organic functional thin film on a substrate to be printed partitioned by a partition, It is an object of the present invention to provide a method for uniforming the height variation between a substrate to be printed and a printing plate.

The invention according to claim 1 of the present invention, which has been made to solve the above problems, includes a substrate, a grid-like first partition and a second partition provided on the substrate, and the first partition and the second partition. An organic light-emitting medium layer including at least a first electrode, a second electrode, and at least an organic light-emitting material, and a first spacer and a second spacer on the lattice-shaped first barrier rib and the second barrier rib. An organic electroluminescence device having two spacers, wherein the first spacer is formed on the second partition so that the distance from two adjacent first partitions is equal. Is an organic electroluminescence element, wherein two are formed in parallel with the second partition at the intersection of the first partition and the second partition.

The invention according to claim 2 of the present invention is characterized in that the height of the apex of the first spacer relative to the surface of the substrate is higher than that of the second spacer. It is an element.

The invention according to claim 3 of the present invention is characterized in that the difference in height between the first spacer and the second spacer is 0.1 μm or more and 0.5 μm or less. It is an element.

The invention according to claim 4 of the present invention is characterized in that an elastic recovery rate of the first spacer and the second spacer with respect to a pressure of 0.01 to 1.5 mN / μm ² at 25 ° C. is 60% or more. It is an organic electroluminescent element of Claim 3.

The invention according to claim 5 of the present invention is characterized in that the height of the first partition wall relative to the substrate surface is lower than that of the second partition wall. It is an element.

The invention according to claim 6 of the present invention includes a step of forming a first electrode on a substrate, a step of forming a grid-shaped first partition and a second partition so as to cover an end of the first electrode, Forming a first spacer and a second spacer on the grid-shaped first and second barrier ribs; and at least an organic light emitting material on the first electrode in a region partitioned by the first and second barrier ribs A process for forming an organic light emitting medium layer, and a process for forming a second electrode on the organic light emitting medium layer, wherein the organic light emitting medium layer is formed. Is a method for producing an organic electroluminescent element, comprising a step of applying an organic light emitting material using a relief printing plate having a convex portion along the longitudinal direction of the first partition wall.

According to the present invention, by providing a flexible spacer on the partition wall substrate, the partition wall substrate becomes flexible, so that there is no gap between the partition wall substrate and the printing plate, printing can be performed with high accuracy, and there is no printing unevenness. Can be manufactured.

Further, according to the present invention, since the height of the first spacer is higher than that of the second spacer, the pressing pressure of the second spacer on both sides is adjusted with the first spacer as a fulcrum, and printing is performed without variation in the amount of ink transferred. be able to.

It is sectional drawing of the organic EL element of this invention. It is a perspective view which shows the partition and spacer of the organic EL element of this invention. It is sectional drawing which looked at the manufacturing process of the organic EL element of this invention from the (a) 2nd partition side, and (b) the sectional view seen from the 1st partition side. It is sectional drawing which looked at the manufacturing process of the conventional organic EL element from the near side of the printing direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings referred to in the following description are for explaining the configuration of the present invention, and the size, thickness, dimensions, and the like of each part shown in the drawings are different from the actual ones.

The printed body of the present invention includes a substrate, a partition provided on the substrate, and an organic functional thin film formed by a printing method in a region partitioned by the partition. Examples of such prints include organic functional thin films such as color filters that are color filter layers, biochips that are organic compound separation layers, and printed circuit boards and TFT substrates that are conductive materials. An organic electroluminescence element (hereinafter referred to as an organic EL element) in which the thin film is an organic light emitting medium layer such as a charge transport layer or an organic light emitting layer will be described as an example.

As shown in FIG. 1, an organic EL element 10 which is a printed material of the present invention includes a substrate 11, a partition wall 13 provided on the substrate, and an organic light emitting medium layer 14 formed in a region partitioned by the partition wall. The partition has a lattice shape formed of a first partition parallel to the first straight line and a second partition parallel to the second straight line. A first electrode 12 is provided below the organic light emitting medium layer, and a second electrode 15 is provided above the organic light emitting medium layer, and has a structure sandwiching the organic light emitting medium layer. Further, a passivation layer 17 and a sealing body 18 are provided on the second electrode 15 for protecting the organic light emitting medium layer from the external environment on the second electrode. The organic light emitting medium layer is formed by a printing method using a printing plate having an image line portion corresponding to the first partition.

<Board>
The board | substrate 11 becomes a support body of the printing body 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 a base material according to which surface light extraction is performed, and a color is not specifically limited, either. A substrate 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 prevent moisture from entering the organic EL element. In particular, in order to avoid intrusion of moisture into the organic light emitting medium, it is preferable to reduce the moisture content and gas permeability coefficient in the substrate.

In the case of forming an organic EL element, an active drive system substrate in which a thin film transistor (TFT) is formed may be used as the substrate 11. When the printed body of the present invention is an active drive organic EL element, a planarization layer is formed on the TFT, and the lower electrode (first electrode 12) of the organic EL element is formed on the planarization layer. It is preferable that the TFT and the lower electrode are electrically connected via a contact hole provided in the planarization layer. By comprising in this way, the outstanding electrical insulation can be obtained between TFT and an organic EL element. The TFT and the organic EL element 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 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; and the like. 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.

When the printed body of the present invention is formed as an organic EL element, the TFT needs to be connected so as to function as a switching element of the organic EL element. The drain electrode of the transistor and the pixel electrode (first electrode of the organic EL element) One electrode 12) 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 12 of the organic EL element are connected through a connection wiring formed in a contact hole that penetrates the planarization film.

Regarding the material of the planarizing film, inorganic materials such as SiO ₂ , spin-on glass, SiN (Si ₃ N ₄ ), TaO (Ta ₂ O ₅ ), organic materials such as polyimide resin, acrylic resin, photoresist material, and black matrix material Etc. can be used. Spin coating, CVD, vapor deposition, etc. can be selected according to 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 planarizing layer is not limited as long as it can cover the lower TFT, capacitor, wiring, etc., and 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 is partitioned by the first partition 131 and the second partition 132, and becomes 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 a high work function such as ITO. 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 of using a substrate on which a TFT is formed as a substrate, it is formed so that conduction can be achieved corresponding to a lower pixel.

<Partition wall>
The partition wall 13 of the present invention is formed so as to partition the light emitting region 133 corresponding to the pixel. 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 includes a first partition wall 131 and a second partition wall 132. In particular, in the case of an active matrix organic EL element, the first partition wall 131 and the second partition wall 132 are formed so as to be orthogonal to each other. The first electrode 12 is partitioned in a lattice shape by the two partition walls (FIG. 2). The arrow AB in FIG. 2 is parallel to the first partition 131, and printing is performed in the direction of the arrow AB. Therefore, the convex portions on the relief plate used for printing the organic functional thin film are formed in a straight line parallel to the first partition 131, and the convex portions of the relief plate are along the first partition 131 and the second is printed on the organic functional thin film. Overcoming the partition wall 132, the first partition wall 131 and the second partition wall 132 are contacted. The first partition 131 and the second partition 132 can be formed in the same shape by the same method, but preferably the second partition 132 has a configuration that does not affect printing more than the first partition 131. Specifically, it is preferable that the second partition wall 132 is lower in height or narrower than the first partition wall 131.

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 plasma or UV can be irradiated to impart liquid repellency to the ink after formation. This method can be applied when the heights of the first partition and the second partition are the same, and the same applies when the second partition is thinner than the first partition.

As a formation method when the heights of the first partition 131 and the second partition 132 are different, for example, an inorganic film such as SiO ₂ is laminated on the substrate by a CVD method or the like, and then the inorganic film is removed using a dry etching method. Then, an opening corresponding to the light emitting region is formed to form a grid-like inorganic film partition wall which becomes the second partition wall and the first partition wall lower part. Next, a photosensitive resin is laminated by a slit coating method, and a striped layer is formed on the grid-like inorganic film through an exposure / development process. The grid-like inorganic film and the strip-shaped inorganic film formed thereon are formed. There is a method of combining the layers into the first partition 131 and the second partition 132. Further, the height may be changed by changing the amount of light applied to the first partition and the second partition using a halftone mask or a gray tone mask.

A preferable height of the partition wall 13 is 0.1 μm to 10 μm. There is no particular limitation on the width of the partition wall, and a range of about 3 μm to 100 μm is preferable. However, if the width of the partition wall becomes too large, the pixel opening becomes narrow, so the second partition wall is made into a forward tapered shape or rounded at a reduced angle. For example, the width of the upper part of the partition wall can be narrowed without the first partition wall penetrating into the light emitting region.
As the shape of the partition wall, in addition to the linear shape shown in the drawing, the intersection of the first partition wall and the second partition wall can be rounded to the light emitting region side so that the ink can easily flow around the opening. Moreover, a part of 2nd partition can be made thin or low.

<Spacer on partition wall>
In the case where the organic light emitting medium layer is formed in the region partitioned by the above-described grid-like partition using a printing method, the ink is transferred from the printing plate to the region partitioned by the partition. Here, if there is a variation in the amount of ink transferred, the film thickness of the organic light emitting medium layer formed in the region partitioned by the partition will vary, resulting in display unevenness on the panel. One of the causes of variations in the ink transfer amount is a gap between the partition wall substrate and the printing plate. This includes not only the accuracy of the gap control of the printing press, but also many factors such as the vibration of the printing press and the accuracy of substrate transport, the height variation of the printing plate itself, the height variation of the partition walls, the variation in the ink amount, etc. It is difficult to control all variations. Therefore, in the present invention, as a means for suppressing these variations, the spacers 14 are provided on the lattice-shaped partition walls to provide flexibility. In particular, by providing two types of spacers 141 and 142 (FIG. 2) having different heights as the spacer 14, the partition walls can be made flexible, and variations in the ink transfer amount can be suppressed, and the film thickness can be reduced within the panel surface. Can obtain a uniform printed body.

As the material of the spacer 14, it is preferable to use a photosensitive resin composition, and generally represented by a monomer having (meth) acrylic acid, 2-hydroxyethyl, acrylamide, N-vinylpyrrolidone or ammonium salt. Alkali solubility obtained by copolymerizing a hydrophilic monomer and a lipophilic monomer represented by (meth) acrylic acid ester, vinyl acetate, styrene, N-vinylcarbazole, etc. by a known method at an appropriate mixing ratio. Resins, photopolymerizable monomers such as radically polymerizable monomers and cationically polymerizable monomers, high-boiling vinyl monomers, di- or poly (meth) acrylates of aliphatic polyhydroxy compounds, di- or poly of alicyclic compounds (Meth) acrylic acid esters, aromatic polyhydroxy compounds Poly (meth) acrylic acid esters photopolymerization initiator as a main component.

Further, the spacer material in the present invention is preferably a spacer having flexibility and a large elastic recovery rate, and if necessary, resin additives such as melamine resin, leveling agent, solvent, chain transfer agent, polymerization It is preferable to add additives such as inhibitors and viscosity modifiers. The optimum elastic recovery rate of the spacer varies depending on the number of spacers provided per unit area, but the elastic recovery rate [elastic deformation (μm) / total for a pressure of 0.01 to 1.5 mN / μm ² at 25 ° C. The deformation (μm) × 100] is preferably 60% or more.

Here, the two types of spacers 141 and 142 will be described with reference to FIGS.
FIG. 3A is a view in which A and B of arrows AB in FIG. 2 overlap each other, and FIG. 3B is a view in which the arrow AB in FIG. 2 is viewed from the side. The first spacer 141 is formed on the second partition wall 132 between the adjacent first partition walls 131 so that the distance from the two adjacent first partition walls 131 to the first spacer 141 is equal. . Two second spacers 142 are formed at the intersection of the first partition 131 and the second partition 132, and the two second spacers are formed adjacent to each other so as to be parallel to the second partition 132.
Thereby, in the process of transferring ink from the convex portion 21 of the relief plate onto the first electrode 12, the first spacer 141 is elastically deformed by the pressing pressure of the convex portion 21, and the two second spacers 142 formed on both sides thereof. Comes into contact with the convex portion 21. FIG. 4 is a cross-sectional view of a process of forming a conventional organic EL element by a printing method, as viewed from the front side in the printing direction to the back side in the printing direction. In the absence of the first spacer 141 and the second spacer 142, poor contact between the convex portion 21 and the substrate occurs due to gap accuracy of the printing press, height variation of the printing plate, and the partition wall (FIG. 4). On the other hand, in the case of the present invention, the pressing force of the second spacers 142 on both sides is adjusted using the first spacer 141 as a fulcrum, and printing can be performed without variation in the ink transfer amount. This is because even when the convex portion is inclined with respect to the substrate, the inclination is corrected by the two second spacers 142 so that the convex portion comes into contact with the substrate horizontally, and the first spacer 141 is a flexible second spacer. The spacer 142 has an effect of preventing the spacer 142 from being crushed by the convex portion of the plate (FIG. 3).

By forming the first spacer 141 having a high height and the second spacer 142 having a low height on the partition wall in this way, the spacer has flexibility, hardness, and elastic recovery rate suitable for printing, and the gap of the printing press. It is possible to prevent poor contact between the plate and the substrate due to variations in accuracy, printing plate, and partition wall height, and printing failure caused thereby. The difference in height between the first spacer 141 and the second spacer 142 is preferably 0.1 to 0.5 μm. If the difference is less than 0.1 μm, the height difference between the printing press and the height of the partition wall may cause unevenness. The inclination of the portion cannot be corrected, and if there is a difference of 0.5 μm or more, the printing pressure applied to the first spacer 141 increases, and the first spacer 141 cannot be elastically restored.

In order to transfer ink from the convex portion of the printing plate onto the pixel region partitioned by the grid-like partition walls, it is necessary to define the height of the combined grid-like partition walls and spacers. The total height of the partition walls and the spacer varies depending on the amount of ink on the printing plate and the viscosity of the ink, but may be 1.0 to 5.0 μm, and more preferably 1.5 to 3.0 μm. . If the partition walls are too low, there is a risk of ink color mixing during printing, and conversely, if they are too high, there is a problem that the ink is not transferred.

<Organic luminescent medium layer>
Next, the organic light emitting medium layer 15 is formed as the organic functional thin film of the present invention. The organic light emitting medium layer 15 in 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. In addition, 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 emission 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 referred to as PEDOT), polymer materials such as a mixture of PEDOT and polystyrene sulfonic acid (hereinafter referred to as PSS) (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 which inorganic materials of Things and the like.

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 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 has a large effect of covering the surface protrusions of the substrate and the first electrode, and it is more preferable to form a film having a thickness of about 50 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 vacuum deposition, spin coating, spray coating, flexography, gravure, microgravure, letterpress printing, intaglio offset, An inkjet method or the like can be used, but the method of forming the organic light emitting material layer is particularly preferably a relief printing method. In the present invention, at least one of the layers constituting the organic light emitting medium layer 15 is formed by the 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 corresponding to colorization, and if formed on the partition wall, current may leak, so that the charge transport layer It is preferably applicable to formation. 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 are formed by the printing method of the present invention, the production 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 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 46.

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. When the second electrode is a cathode, a substance having a high electron injection efficiency into the organic light emitting medium layer 15 and a low work function is used. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by about 1 nm at the interface contacting the light emitting medium, and Al or Cu having high stability and conductivity is laminated. May be 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 An alloy system with a metal element such as Cu or Cu may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used. In the case of a so-called top emission structure in which light is extracted from the second electrode side, it is preferable to select a light-transmitting material. In this case, after thinly providing Li and Ca having a low work function, a metal composite oxide such as ITO (indium tin composite oxide), indium zinc composite oxide, or zinc aluminum composite oxide may be laminated. The organic light emitting medium layer 15 may be laminated with a metal oxide such as ITO by doping a small amount of a metal such as Li or Ca having a low work function.

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 a 2nd electrode, About 10 nm-1000 nm are desirable. Moreover, when utilizing a 2nd electrode as a translucent electrode layer, about 0.1-10 nm is desirable for the film thickness in the case of using metal materials, such as Ca and Li.

<Passivation layer>
Next, a passivation layer is formed. Examples of the material for the passivation layer 17 include metal oxides such as silicon oxide and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride, aluminum nitride, and carbon nitride, silicon oxynitride, and the like. A metal carbide such as metal oxynitride or silicon carbide, and a laminated film with a polymer resin film such as an acrylic resin, an epoxy resin, a silicone resin, or a polyester resin may be used as necessary. In particular, it is preferable to use silicon oxide (SiO _x ), silicon nitride (SiN _x ), and silicon oxynitride (SiO _x N _y ) from the viewpoints of barrier properties and transparency. Alternatively, a laminated film or a gradient film may be used.

As a method for forming the passivation layer 17, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or a CVD method can be used depending on the material. Further, it is preferable to use the CVD method in terms of translucency. As the CVD method, a thermal CVD method, a plasma CVD method, a catalytic CVD method, a VUV-CVD method, or the like can be used. In addition, as a reaction gas in the CVD method, a gas such as N ₂ , O ₂ , NH ₃ , H ₂ , N ₂ O is added to an organic silicon compound such as monosilane, hexamethyldisilazane (HMDS), or tetraethoxysilane. It may be added as necessary. For example, the density of the film may be changed by changing the flow rate of silane, and hydrogen or carbon may be contained in the film by the reactive gas used. The film thickness of the sealing layer varies depending on the electrode step of the organic EL element, the height of the partition walls of the substrate, the required barrier characteristics, and the like, but generally about 10 nm to 10,000 nm is generally used.

<Sealing body>
As an organic EL device, it is possible to emit light by sandwiching a light emitting material between electrodes and passing an electric current. However, since the organic light emitting material is easily deteriorated by moisture and oxygen in the atmosphere, it is usually cut off from the outside. A sealing body is provided. The sealing body 18 can be formed, for example, by providing a resin layer 18b on the sealing material 18a.
The sealing material 18a needs to be a base material with low moisture and oxygen permeability. Examples of the material include ceramics such as alumina, silicon nitride, and boron nitride, glass such as alkali-free glass and alkali glass, metal foil such as quartz, aluminum, and stainless steel, and moisture-resistant film. Examples of moisture-resistant films include films formed by CVD of SiOx on both sides of plastic substrates, films with low permeability and water-absorbing films, or polymer films coated with a water-absorbing agent. The water vapor transmission rate is preferably 10 ⁻⁶ g / m ² / day or less.

As an example of the material of the resin layer 18b, a photocurable adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin made of an epoxy resin, an acrylic resin, a silicone resin, or the like, or ethylene ethyl acrylate (EEA) ) Acrylic resins such as polymers, vinyl resins such as ethylene vinyl acetate (EVA), thermoplastic resins such as polyamide and synthetic rubber, and thermoplastic adhesive resins such as acid-modified products of polyethylene and polypropylene. . Examples of methods for forming a resin layer on a sealing material include solvent solution method, extrusion lamination method, melting / hot melt method, calendar method, nozzle coating method, screen printing method, vacuum laminating method, hot roll laminating method. And so on. A material having a hygroscopic property or an oxygen absorbing property may be contained as necessary. Although the thickness of the resin layer formed on a sealing material is arbitrarily determined by the magnitude | size and shape of the organic EL element to seal, about 5-500 micrometers is desirable. In addition, although it formed as a resin layer on the sealing material here, it can also form directly in the organic EL element side.

Finally, the organic EL element 10 and the sealing body 18 are bonded together in a sealing chamber. When the sealing body has a two-layer structure of a sealing material and a resin layer, and a thermoplastic resin is used for the resin layer, it is preferable to perform only pressure bonding with a heated roll. When a thermosetting adhesive resin or a photocurable adhesive resin is used, it is preferable to carry out light or heat curing in a state where it is roll-bonded or flat-bonded.

Before or instead of sealing with a sealing body, sealing with an inorganic thin film can be performed, for example, a 150 nm silicon nitride film is formed using a CVD method as a passivation film.

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, a photosensitive polyimide resin was formed with a coating thickness of 1.0 μm by a slit coating method, and lattice-like partition walls 13 were formed by an exposure / development process.

Next, on the grid-like partition wall 13, a photosensitive acrylic resin as a spacer 14 was slit-coated with a thickness of 1.0 μm. As a mask used for exposure, an ITO film is formed in the chrome mask opening corresponding to the second spacer 142 forming portion, and the ultraviolet transmittance is higher than that of the opening corresponding to the first spacer 141 forming portion. A chrome mask cut to 50% was used. By using this mask, the exposure amount of the second spacer 142 part is reduced. Therefore, the height of the second spacer 142 is 0 while the first spacer 141 after the exposure is 1.0 μm high. It was as low as 7 μm.

Next, an ink-like polymer hole transport material is printed on the opening 133, which is a region partitioned by the grid-like partition walls 13, using the relief printing plate 21, and dried to charge transport having a film thickness of 50 nm. Layer 15 was formed. As the polymer hole transport material, a polythiophene derivative (PEDOT) was used, which was dispersed in water to form an ink. Next, a polyfluorene material was printed and formed as an organic light emitting layer 15 with a thickness of 80 nm using a relief printing method.

Next, on the organic light-emitting medium layer, 5 nm of Ba and 100 nm of Al are stacked as the second electrode layer 16 by vapor deposition, and 5 μm of SiNx film is stacked as the passivation layer 17. Finally, glass, 18b is used as the resin layer 18 a. Sealed with a photo-curable epoxy adhesive.

When the first electrode was used as an anode and the second electrode was used as a cathode and the emission was observed from the first electrode side, the emission unevenness in the panel surface (minimum luminance / maximum luminance × 100) was 5% or less.

(Comparative Example 1)
In Comparative Example 1, both the first spacer 141 and the second spacer 142 are 1 by using a chromium mask that does not change the ultraviolet transmittance in the exposure process of the first spacer 141 and the second spacer 142 in Example 1. It was formed to a thickness of 0.0 μm. As a result, the printing plate 21 hits all of the first spacer 141 and the second spacer 142 at the same time during printing, so that the gap could not be adjusted sufficiently.
When the first electrode was used as an anode and the second electrode was used as a cathode to emit light and the light emission was observed from the first electrode side, the emission unevenness in the panel surface (minimum luminance / maximum luminance × 100) was 20%.

(Comparative Example 2)
In Comparative Example 2, only the first spacer 141 was formed as the spacer 14 in Example 1.
As a result, the printing plate 21 was pressed against the first spacer 141 during printing, but since the second spacer 142 was not present, it was pushed to the plastic deformation amount of the first spacer 141, and the second layer was formed as the organic light emitting medium layer. When forming the light emitting layer, the first spacer was in a crushed state, resulting in printing failure.
When the first electrode was used as an anode and the second electrode was used as a cathode to emit light, the light emission was observed from the first electrode side. As a result, the uneven light emission within the panel surface (minimum luminance / maximum luminance × 100) was 40%.

(Comparative Example 3)
In Comparative Example 3, only the second spacer 142 was formed as the spacer 14 in Example 1.
As a result, during printing, the printing plate 21 hit the two second spacers 142 and pushed in to some extent to adjust the gap, but the gap could not be adjusted sufficiently.
When the first electrode was used as the anode and the second electrode was used as the cathode and the emission was observed from the first electrode side, the emission unevenness in the panel surface (minimum luminance / maximum luminance × 100) was 15%.

DESCRIPTION OF SYMBOLS 10 ... Organic EL element 11 ... Board | substrate 12 ... 1st electrode 13 ... Partition 131 ... 1st partition 132 ... 2nd partition 133 ... The light emission area | region 14 divided into the partition ... spacer 141 ... first spacer 142 ... second spacer 15 ... organic light emitting medium layer 16 ... second electrode 17 ... passivation layer 18 ... sealing body 18a ... Sealing material 18b ... Resin layer 21 ... Convex portion 22 ... Letter plate cylinder 23 ... Ink

Claims (6)

A substrate, grid-like first and second partitions provided on the substrate, at least a first electrode and a second electrode formed in a region partitioned by the first and second partitions, and An organic electroluminescent device comprising an organic light emitting medium layer containing at least an organic light emitting material, and a first spacer and a second spacer on the lattice-shaped first partition and second partition,
The first spacer is formed on the second partition so that the distance from two adjacent first partitions is equal, and the second spacer is on the intersection of the first partition and the second partition. Two organic electroluminescence elements are formed so as to be parallel to the second partition wall. 2. The organic electroluminescence device according to claim 1, wherein a height of an apex of the first spacer with respect to the surface of the substrate is higher than that of the second spacer. The organic electroluminescence device according to claim 2, wherein a difference in height between the first spacer and the second spacer is 0.1 µm or more and 0.5 µm or less. The organic electroluminescence according to claim 3, wherein an elastic recovery rate of the first spacer and the second spacer with respect to a pressure of 0.01 to 1.5 mN / µm ² at 25 ° C is 60% or more. element. 5. The organic electroluminescence element according to claim 1, wherein a height of the first partition with respect to the surface of the substrate is lower than that of the second partition. Forming a first electrode on the substrate;
Forming a grid-like first partition and a second partition so as to cover an end of the first electrode;
Forming a first spacer and a second spacer on the grid-like first partition and the second partition;
Forming an organic light emitting medium layer containing at least an organic light emitting material on the first electrode in the region partitioned by the first partition and the second partition;
Forming a second electrode on the organic light emitting medium layer;
A method for producing an organic electroluminescence device comprising:
The step of forming the organic light emitting medium layer includes a step of applying an organic light emitting material using a relief printing plate having a convex portion along the longitudinal direction of the first partition. Manufacturing method.

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