JP2014199857A - Organic el display device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive organic EL display device which suppresses deterioration in color purity of a red organic EL element and a green organic EL element due to the influence of a blue light-emitting layer and whose manufacturing process is easy, and to provide a method of manufacturing the same.SOLUTION: An organic EL display device 1 includes: a blue light-emitting layer host layer formed on that portion of a hole injection/transport layer in which a red light-emitting layer and a green light-emitting layer are not formed, on the red light-emitting layer, and on the green light-emitting layer; and a blue light-emitting layer which is formed on the entire surface of the blue light-emitting layer host layer and contains at least a host material of the blue light-emitting layer host layer and a hole-transporting blue dopant material.

Description

  The present invention relates to a display device, and more particularly to an organic EL display device and a manufacturing method thereof.

  The organic light emitting display device recombines electrons and holes injected in the organic light emitting layer in the light emitting medium layer by applying a voltage to the conductive light emitting medium layer. The organic light emitting molecules in the organic light emitting layer are once excited by the recombination energy, and then return from the excited state to the ground state. At this time, the organic light emitting display device emits light by taking out the released energy as light. In order to apply a voltage to the organic medium layer, a pixel electrode and a counter electrode are provided on both sides of the light emitting medium layer, and at least one electrode is transparent to extract light from the light emitting layer to the outside. Has light properties. As an example of the structure of such an organic light emitting display device, a structure in which a light transmitting pixel electrode, a light emitting medium layer, and a counter electrode are sequentially stacked on a light transmitting substrate can be given. Moreover, the aspect which utilizes the pixel electrode formed on a board | substrate and the counter electrode formed on a light emitting medium layer as a cathode is mentioned.

  Furthermore, for the purpose of increasing the luminous efficiency of the organic light emitting display device, in addition to the hole transport layer and the hole injection layer provided between the anode and the organic light emitting layer, electrons are interposed between the organic light emitting layer and the cathode. In many cases, a transport layer and an electron injection layer are appropriately selected and provided. These hole transport layer, hole injection layer, electron transport layer, and electron injection layer are called carrier transport layers. The carrier transport layer, the organic light emitting layer, the hole blocking layer, the electron blocking layer, the insulating layer, etc. are collectively referred to as a light emitting medium layer.

  When an image display device is manufactured, an image is displayed by a large number of pixels arranged vertically and horizontally on a substrate. For this purpose, it is necessary to selectively dispose a light emitting material, a hole injection material, or the like on the pixel electrode to form an independent organic light emitting display device for each pixel. At that time, in order to uniformly distribute the material to each pixel and to uniformly emit light, a method of providing partition walls that partition each pixel in advance is generally used.

Here, there are three general combinations of emission colors: red, green, and blue. Further, the lifetime of the organic light emitting display device is determined by the organic light emitting medium layer having a short lifetime. At present, the lifetime of blue-emitting organic light-emitting elements tends to be shorter than that of red and green organic light-emitting elements. Therefore, extending the lifetime of the blue organic light-emitting element has been a problem for achieving long-term reliability as an organic light-emitting display device.
In addition, materials used for a light emitting layer or the like for forming an organic EL display device are roughly classified into a low molecular material and a high molecular material. In general, it is known that a low molecular weight material exhibits higher luminous efficiency and longer life, and blue performance is particularly high.

  The low molecular weight material is generally formed using a vacuum evaporation method. The vacuum deposition method has an advantage that it is not necessary to dissolve an organic material in a solvent, and a step of removing the solvent after film formation is unnecessary. However, vacuum vapor deposition is difficult to separate with a metal mask, and has the disadvantages that it is difficult to apply to large screen substrates and difficult to mass-produce, especially because of the high equipment manufacturing cost in the production of large panels. It was.

In recent years, active research has been conducted on forming a light-emitting layer by a wet method such as a coating method or a printing method by dissolving or dispersing a low-molecular or high-molecular material in a solvent. In this case, as compared with the organic light emitting display device using the above-described vacuum vapor deposition method, there is an advantage that film formation under atmospheric pressure is possible and equipment cost is low.
These are generally formed of a material that is easily dissolved in a solvent. Accordingly, a wet coating method such as a spin coating method under atmospheric pressure, a letterpress printing method, a letterpress inversion offset printing method (for example, refer to Patent Documents 1 and 2), an ink jet method (for example, refer to Patent Documents 3 to 4), Each layer can be formed by using a printing method such as a nozzle printing method (see, for example, Patent Document 5), thereby reducing the cost of manufacturing equipment and improving productivity.

However, among the luminescent materials used in the wet method, in particular, the blue luminescent material has low luminance and lifetime characteristics and is not practical. Therefore, it has been difficult to pattern the blue luminescent layer by the wet method.
In response to this problem, a display device is disclosed that is formed by a vacuum deposition method using a blue light emitting layer and a subsequent layer, which have insufficient characteristics by a wet method, on a red light emitting layer and a green light emitting layer formed by a wet method. (Patent Document 6). Such a structure eliminates the need for fine patterning on the blue light-emitting layer, so that the possibility of enlargement is particularly high.

JP 2003-17248 A JP 2004-296226 A Japanese Patent No. 3541625 JP 2009-267299 A JP 2001-189192 A JP 2006-140434 A

  However, the organic EL display device of Patent Document 1 has a problem that the color purity of the red organic EL element and the green organic EL element is lowered. Since the blue light emitting layer is directly laminated on the red and green light emitting layers, carriers move from the red and green light emitting layers to the blue light emitting layer, and light emission from the blue light emitting layer is added, thereby producing a red organic EL element and a green organic EL element. The chromaticity at will change. Accordingly, there has been a demand for reducing blue light emission in red and green organic EL elements.

  The present invention is an organic EL display device in which a blue light-emitting layer is laminated on a formed red and green light-emitting layer by vapor deposition or the like. Then, an object of the present invention is to provide an organic EL display device and a method for manufacturing the organic EL display device that suppresses a decrease in color purity due to an influence from a blue light emitting layer in a red organic EL element and a green organic EL element, and that is easy to manufacture and inexpensive.

In order to solve the above-described problems, an organic EL display device according to an aspect of the present invention includes a substrate and a plurality of organic EL display devices provided for each of a red organic EL element, a green organic EL element, and a blue organic EL element on the substrate. A pixel electrode, a hole injection / transport layer having at least one of hole injection and hole transport properties formed on the pixel electrode, and the hole injection on the pixel electrode for the red organic EL element A red light emitting layer formed with a transport layer interposed therebetween, a green light emitting layer formed with the hole injection / transport layer sandwiched on a pixel electrode for the green organic EL element, and at least the light emitting layer formed A blue light emitting layer host layer formed on the hole injecting / transporting layer, the red light emitting layer and the green light emitting layer, and at least the blue light emitting layer formed on the entire surface of the blue light emitting layer host layer. Layer host layer host material And a blue light-emitting layer containing a hole-transporting blue dopant material, an electron injection / transport layer formed on the entire surface of the blue light-emitting layer and having at least one of electron injection and electron transport characteristics; And a counter electrode formed on the transport layer.
At this time, the film thickness of the blue light emitting layer host layer may be 5 nm or more and 15 nm or less.
The blue light emitting layer host material may have electron transport properties.

The method of manufacturing an organic EL display device according to an aspect of the present invention includes: forming each pixel electrode corresponding to each of a red organic EL element, a green organic EL element, and a blue organic EL element on a substrate; A step of forming a hole injection / transport layer having at least one of hole injection and hole transport characteristics by a wet method, and on each pixel electrode for the red organic EL element and the green organic EL element; A step of forming a red light emitting layer and a green light emitting layer by a wet method with the hole injection / transport layer interposed therebetween, on the hole injection / transport layer where the light emitting layer is not formed, on the red light emitting layer, And a step of forming a blue light emitting layer host layer on the entire surface of the green light emitting layer by vapor deposition, a step of forming the blue light emitting layer on the entire surface of the blue light emitting layer host layer by an evaporation method, and the entire surface of the blue light emitting layer. Electron injection into And having a step of forming sequentially an electron injecting and transporting layer and the counter electrode having at least one characteristic of the electron transport.
At this time, the light emitting layer is formed by coating, and it is preferable to use inkjet, nozzle printing, relief printing, gravure printing, or reverse offset printing as the coating.

According to the aspect of the present invention, a red light emitting layer and a green light emitting layer are formed, and blue light is emitted on the entire surface of the red light emitting layer, the green light emitting layer, and the hole injection / transport layer in which the light emitting layer is not formed. A layer host layer is formed, and further a blue light emitting layer containing at least the host material of the blue light emitting layer host layer and the blue dopant material having a hole transporting property is formed. Thereby, carrier movement from the red and green light emitting layers to the blue light emitting layer is suppressed on the entire surface of the blue light emitting layer host layer, and as a result, light emission of the blue light emitting layer is suppressed, and the red organic EL element and the green organic EL A decrease in color purity due to the influence from the blue light emitting layer in the device can be suppressed.
Furthermore, since the host material of the blue light emitting layer and the host material of the blue light emitting layer are the same, the manufacturing process is easy without increasing the number of vapor deposition sources of the apparatus, there is little variation, and the product yield is low. An organic EL display device can be manufactured.

1 is a cross-sectional view schematically showing a configuration of an organic light emitting display device according to an embodiment of the present invention. It is a schematic sectional drawing which shows typically the relief printing apparatus which concerns on embodiment of this invention.

  An organic light emitting display device according to an embodiment of the present invention includes a pixel electrode provided for each of a red organic EL element, a green organic EL element, and a blue organic EL element on a substrate, and holes formed on the pixel electrode. A hole injection / transport layer having at least one of injection or hole transport characteristics, a red light emitting layer and a green light emitting layer formed on the hole injection / transport layer, and the red light emitting layer and the green light emitting layer. Blue light emitting layer host layer formed on the entire surface of the hole injection / transport layer, blue light emitting layer formed on the entire surface of the blue light emitting layer host layer, and electron injection formed on the entire surface of the blue light emitting layer in this order. Alternatively, an electron injection / transport layer having at least one of the characteristics of electron transport and a counter electrode are formed.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows a configuration of an organic light emitting display device according to the present embodiment. The organic light emitting display device 1 according to the present embodiment is an organic light emitting display device having a so-called active matrix structure. The configuration is as follows.
That is, the substrate is made of a translucent substrate 2 on which a thin film transistor (TFT) is formed, and a plurality of pixel electrodes 3 are formed on one surface of the translucent substrate 2 as shown in FIG. Yes. Each pixel electrode 3 is linearly partitioned by a partition wall 4. A hole injection layer 5 is stacked on the plurality of pixel electrodes 3, and a hole transport layer 6 is stacked on the hole injection layer 5.

  Among the pixel electrodes 3, the red light emitting layer 7 or the green light emitting layer 8 is disposed on the pixel electrodes 3 for the red organic EL element and the green organic EL element with the hole injection layer 5 and the hole transport layer 6 interposed therebetween. Correspondingly laminated. A blue light emitting layer host layer 9 is laminated on the red light emitting layer 7, the green light emitting layer 8, and the hole transport layer 6 on which the light emitting layer is not laminated, and the entire surface on the blue light emitting layer host layer 9. A blue light emitting layer 10 is laminated on the substrate. Further, an electron transport layer 11 is laminated on the blue light emitting layer 10, and a counter electrode 12 disposed to face the pixel electrode 3 is formed on the electron transport layer 11. Further, a resin layer 13 and a sealing substrate 14 are formed so as to cover the counter electrode 12. FIG. 1 illustrates the case where the blue light emitting layer host layer 9 is also formed on the partition 4.

In the following description, the case where the pixel electrode 3 is an anode and the counter electrode 12 is a cathode will be described as an example. The organic light emitting display device 1 according to this embodiment may have a so-called passive matrix structure.
The translucent substrate 2 is a substrate that supports the pixel electrode 3, the organic light emitting layer, and the counter electrode 12, and is made of a film or sheet such as metal, glass, or plastic. As the plastic film, polyethylene terephthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, or polycarbonate can be used.

In addition, another gas barrier film such as a ceramic vapor-deposited film, polyvinylidene chloride, polyvinyl chloride, saponified ethylene-vinyl acetate copolymer is laminated on the other surface of the translucent substrate 2 where the pixel electrode 3 is not formed. May be.
The translucent substrate 2 of the present embodiment may be an active drive system substrate on which a thin film transistor (TFT) is formed. When the printed body of the present embodiment is an active drive type organic EL element, a planarization layer is formed on the TFT, and a lower electrode of the organic EL element is provided on the planarization layer. In addition, the TFT and the lower electrode are preferably 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. In the case of a bottom emission type organic EL element, it is necessary to use a translucent substrate.

  Next, a layer made of the material of the pixel electrode 3 is formed on the substrate, and patterning is performed as necessary. The layer made of the material of the pixel electrode 3 is partitioned by the partition walls 4 and becomes the pixel electrode 3 corresponding to each pixel. Examples of the material of the pixel electrode 3 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, these metal oxides, Either 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 pixel electrode 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 pixel electrode. Although the optimum value of the film thickness of the pixel electrode 3 varies depending on the element configuration of the organic EL display, it is not less than 100 mm and not more than 10,000 mm, more preferably not less than 100 mm and not more than 3000 mm, regardless of single layer or stacked layers.

As a method for forming the pixel electrode 3, depending on the material, a dry film forming method such as a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, a gravure printing method, or a screen printing method is used. A wet film forming method such as a method can be used.
The partition walls 4 are formed so as to cover the end portions of the pixel electrodes 3 in order to prevent the organic light emitting medium layers formed on the pixel electrodes 3 from mixing with each other. It is desirable that the shape is a line that divides 3.

  As a method of forming the partition walls 4, as in the conventional method, an inorganic film is uniformly formed on the substrate, masked with a resist, and then dry etching is performed, or a photosensitive resin is laminated on the substrate. And a method of forming a predetermined pattern by photolithography. If necessary, a water repellent can be added, or plasma or UV can be irradiated to impart liquid repellency to the ink after formation.

The material of the partition 4 needs to have insulating properties, and a photosensitive material or the like can be used. The photosensitive material may be a positive type or a negative type, a photo-curing resin of a photo radical polymerization system, a photo cationic polymerization system, or a copolymer containing an acrylonitrile component, polyvinyl phenol, polyvinyl alcohol. , Novolac resin, polyimide resin, cyanoethyl pullulan, and the like can be used. Further, as a partition wall forming _material, it is also possible to use SiO 2, TiO ₂ or the like.
The preferable height of the partition wall 4 is 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 2 μm or less. If the height of the partition wall 4 exceeds 10 μm, the formation and sealing of the counter electrode is hindered, and if it is less than 0.1 μm, the end of the pixel electrode 3 cannot be covered, or adjacent pixels are formed when the organic light emitting medium layer is formed. This is for short-circuiting or mixing colors.

  Next, an organic light emitting medium layer is formed as the organic functional thin film of this embodiment. As described above, the organic light emitting medium layer in the present embodiment includes at least the hole injection layer 5 formed on the upper surface of the pixel electrode 3, the hole transport layer 6 stacked on the hole injection layer 5, A red light emitting layer 7 and a green light emitting layer 8 laminated on the hole transport layer 6; a blue light emitting layer host layer 9 laminated on the red light emitting layer 7, the green light emitting layer 8 and the hole transport layer 6; The blue light emitting layer 10 laminated on the host layer 9 and the electron transport layer 11 laminated on the blue light emitting layer 10 are sequentially laminated.

  The hole injection layer 5 and the hole transport layer 6 advance holes injected from the pixel electrode 3 serving as an anode toward the counter electrode 12 serving as a cathode, and electrons pass through the holes while passing electrons. It has a function to prevent progress. A positive hole injection layer having a function of stabilizing the injection of holes from the pixel electrode 3 when an electric field is applied, and a positive function having a function of transporting holes injected from the pixel electrode 3 into the light emitting layer by the force of the electric field. It may be a case having either one of the hole transport layers, and may have both functions of a hole injection layer and a hole transport layer. The hole injection layer or the hole transport layer may be composed of one layer or a plurality of layers. For example, as shown in FIG. 1, the hole injection layer 5 and the hole transport layer 6 are formed between the light emitting layer and the pixel electrode 3.

Examples of hole transport materials used for the hole injection layer 5 and the hole transport layer 6 include metal phthalocyanines such as copper phthalocyanine and tetra (t-butyl) copper phthalocyanine, and metal-free phthalocyanines, quinacridone compounds, 1-bis (4-di-p-tolylaminophenyl) cyclohexane, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine, Aromatic amine low molecular hole injection and transport materials such as N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine, polyaniline, polythiophene , Polyvinyl carbazole, polymeric hole transport materials such as poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid, polythiophene oligomer materials _{, Cu 2 O, Cr 2 O} 3, Mn 2 O 3, FeOx (x~0.1), NiO, CoO, Pr 2 O 3, Ag 2 O, MoO 2, Bi 2 O 3, ZnO, TiO 2, It can be selected from inorganic materials such as SnO ₂ , ThO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO ₂ , and other existing hole injection / transport materials.

As a solvent for dissolving or dispersing the hole injection transport material, toluene, xylene, anisole, dimethoxybenzene, tetralin, cyclohexanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, isopropyl alcohol, ethyl acetate, Among butyl acetate, water, etc., any one or a mixture thereof can be mentioned.
A surfactant, an antioxidant, a viscosity modifier, an ultraviolet absorber, or the like may be added to the solution or dispersion of the above-described hole injection / transport material as necessary. Examples of the viscosity modifier include: Polystyrene, polyvinyl carbazole, or the like can be used.

  As a method for forming the hole injection layer 5 and the hole transport layer 6, depending on the materials used for the hole injection layer 5 and the hole transport layer 6, spin coating, bar coating, wire coating, slit coating, spray coating, Wet methods such as curtain coating, flow coating, letterpress printing, letterpress reverse printing, ink jet method, nozzle printing method, resistance heating evaporation method, electron beam evaporation method, reactive evaporation method, ion plating method, sputtering method, etc. An evaporation method can be used.

  An interlayer layer may be formed on the hole injection layer 5 and the hole transport layer 6. Examples of materials used for the interlayer layer include polymers containing aromatic amines such as polyvinyl carbazole or derivatives thereof, polyarylene derivatives having aromatic amines in the side chain or main chain, arylamine derivatives, and triphenyldiamine derivatives. . These materials are dissolved or dispersed in a solvent, and wet methods such as spin coating, bar coating, wire coating, slit coating, spray coating, curtain coating, flow coating, letterpress printing, letterpress reverse printing, ink jet printing, nozzle printing, etc. Can be used.

The red light emitting layer 7, the green light emitting layer 8, and the blue light emitting layer 10 are functional materials of an organic light emitting layer that emits red, green, and blue light when a voltage is applied.
The blue light emitting layer 10 is composed of at least one kind of blue light emitting layer host material and a blue light emitting layer dopant material, and the red light emitting layer 7, the green light emitting layer 8, and the light emitting layers 7 and 8 are not formed. A blue light emitting layer host layer 9 made of a blue light emitting layer host material is formed on the hole transport layer 6, and a blue light emitting layer 10 is formed on the blue light emitting layer host layer 9.

  The red light emitting layer 7 and the green light emitting layer 8 are prepared by spin-coating, bar coating, wire coating, slit coating, spray coating, curtain coating, flow coating, organic light emitting ink (ink) dissolved or dispersed on the hole transport layer 6, It is formed by attaching using a wet method such as letterpress printing, letterpress reversal offset printing, ink jet method, or nozzle printing method, and then drying.

  Organic light-emitting materials for forming organic light-emitting layers such as the red light-emitting layer 7 and the green light-emitting layer 8 are, for example, coumarin-based, perylene-based, pilin-based, anthrone-based, porphyrene-based, quinacridone-based, N, N′-dialkyl-substituted quinacridone-based, Light-emitting pigments such as naphthalimide, N, N'-diaryl-substituted pyrrolopyrrole, iridium complex, etc. dispersed in polymers such as polystyrene, polymethylmethacrylate, polyvinylcarbazole, polyarylene, polyarylene Examples include vinylene-based and polyfluorene-based polymer materials. However, the present invention is not limited to these.

  These organic light emitting materials are dissolved or stably dispersed in a solvent to form an organic light emitting ink. Examples of the solvent for dissolving or dispersing the organic light emitting material include toluene, xylene, acetone, anisole, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or a mixed solvent thereof. Among them, aromatic organic solvents such as toluene, xylene, and anisole are preferable from the viewpoint of the solubility of the organic light emitting material. Moreover, surfactant, antioxidant, a viscosity modifier, a ultraviolet absorber, etc. may be added to organic luminescent ink as needed.

  In addition to the above-described polymer materials, organic light-emitting materials for forming the organic light-emitting layer are 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8 -Quinolate) aluminum complex, tris (4-methyl-8-quinolate) aluminum complex, bis (8-quinolate) zinc complex, tris (4-methyl-5-trifluoromethyl-8-quinolate) aluminum complex, tris (4 -Methyl-5-cyano-8-quinolato) 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) phenolate Aluminum complex, tris (8-quinolinolato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, poly-2,5-di Low molecular weight light emitting materials such as heptyloxy-para-phenylene vinylene can also be used.

As a formation method of the blue light emitting layer host layer 9, vacuum evaporation methods, such as resistance heating vapor deposition method, electron beam vapor deposition method, and reactive vapor deposition method, can be used according to the material to be used. The film thickness is preferably in the range of 5 nm to 15 nm. In this case, providing the blue light emitting layer host layer 9 makes it difficult for excitation energy generated in the red light emitting layer 7 and the green light emitting layer 8 to move to the blue light emitting layer 10, thereby suppressing blue light emission.
Furthermore, when the blue light emitting layer host layer 9 is made of a material having an electron transporting property, the holes of the red light emitting layer 7 and the green light emitting layer 8 from the blue light emitting layer 10 are difficult to move to the blue light emitting layer 10, and Since the electron injection from the light emitting layer 10 to the red light emitting layer 7 and the green light emitting layer 8 is promoted, blue light emission can be further suppressed.

Examples of the organic light emitting material forming the blue light emitting layer host layer 9 include anthracene derivatives, fluorene derivatives, benzene derivatives, perylene derivatives, pyrene derivatives, and the like. However, the present invention is not limited to these.
As a method for forming the blue light emitting layer 10, a vacuum vapor deposition method such as a resistance heating vapor deposition method, an electron beam vapor deposition method, or a reactive vapor deposition method can be used depending on the material used. The mixed material and the blue light emitting layer dopant material are mixed to form a film, or simultaneously formed to form a mixed film.

Since the material used for the blue light-emitting layer host layer 9 and the host material of the blue light-emitting layer 10 are the same, when they are formed simultaneously to form a mixed film, there is no need to provide a separate vapor deposition source, and the initial investment of equipment can be suppressed. it can.
Examples of the organic light-emitting material forming the organic light-emitting layer such as the blue light-emitting layer 10 include perylene-based, pyrroline-based, naphthalimide-based, N, N′-diaryl-substituted pyrrolopyrrole-based, and iridium complex-based materials. It is not limited to.

Examples of the electron transport material used for the electron transport layer 11 include 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. Alternatively, these electron transport materials may be used as an electron injection layer by doping a small amount of alkali metal or alkaline earth metal having a low work function such as sodium, barium, or lithium.
As a method for forming the electron transport layer 11, a vacuum evaporation method such as a resistance heating evaporation method, an electron beam evaporation method, a reactive evaporation method, an ion plating method, or a sputtering method can be used depending on the material to be used.

Next, the counter electrode 12 is formed. When the counter electrode is a cathode, a substance having a high electron injection efficiency into the organic light emitting medium layer 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 in contact with the light emitting medium, and Al or Cu having high stability and conductivity is placed. You may use it, laminating | stacking. 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, An alloy system with a metal element such as Al or Cu may be used.
As a method for forming the counter electrode 12, 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 counter electrode, 10 nm or more and 1000 nm or less are desirable.

  Next, for example, a passivation layer may be formed on the counter electrode between the counter electrode 12 and the sealing material. Examples of the material for the passivation layer 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, and silicon oxynitride. A laminated film of a metal carbide such as metal oxynitride or silicon carbide, and 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, from the viewpoint of barrier properties and transparency, it is preferable to use silicon oxide (SiOx), silicon nitride (SiNx), or silicon oxynitride (SiOxNy). Furthermore, a laminated film in which the film density is variable depending on the film forming conditions. Alternatively, a gradient membrane may be used.

  As a method for forming the passivation layer, 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. It is preferable to use a 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 , or N ₂ O is added to an organic silicone 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 thickness of the passivation layer varies depending on the electrode step of the organic EL element, the height of the partition wall of the substrate, the required barrier characteristics, and the like, but generally about 0.01 μm to 10 μm is generally used.

Since the organic light emitting material is easily deteriorated by moisture and oxygen in the atmosphere, a sealing material for blocking the organic light emitting medium layer from the outside is provided. The sealing material can be formed by providing, for example, the sealing substrate 14 and the resin layer 13. The sealing substrate 14 needs to be a base material having 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 SiO _x 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 permeability of the film is preferably 10 ⁻⁶ g / m ² / day or less.

  As an example of the material of the resin layer 13, a photo-curing adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin made of epoxy resin, acrylic resin, 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 the method for forming the resin layer 13 include a solvent solution method, an extrusion lamination method, a melting / hot melt method, a calendar method, a nozzle coating method, a screen printing method, a vacuum laminating method, a hot roll laminating method, and the like. 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, 5 micrometers or more and 500 micrometers or less are desirable.

  The organic EL element and the sealing substrate 14 are bonded together in a sealing chamber. When the sealing material has a two-layer structure of the sealing substrate 14 and the resin layer 13 and a thermoplastic resin is used for the resin layer 13, it is preferable to perform only the pressure bonding with a heated roll. In the case where a thermosetting adhesive resin or a photocurable adhesive resin is used for the resin layer 13, it is preferable to perform light or heat curing in a state where it is roll-bonded or flat-bonded.

Next, an outline of a method for manufacturing the organic light emitting display device 1 having the above-described configuration by a relief printing method and a vacuum deposition method will be described. The present invention is not limited to this, and as described above, a nozzle printing method or the like can be used instead of the relief printing method.
First, the pixel electrode 3 is formed on the translucent substrate 2 on which the thin film transistor is formed so as to be connected to the thin film transistor. This is because an ITO film is formed on the entire surface of the translucent substrate 2 using a sputtering method, and further, exposure and development are performed by a photolithography technique, and a main part remaining as the pixel electrode 3 is covered with a photoresist. Then, unnecessary portions are etched with an acid solution to remove the ITO film. In this way, a plurality of pixel electrodes 3 arranged at predetermined intervals are formed.

  Next, the partition walls 4 are formed between the pixel electrodes 3. In this method, a photoresist is applied on the translucent substrate 2 and the pixel electrode 3, and exposure and development are performed by a photolithography technique so that the photoresist remains between the pixel electrodes 3. Thereafter, the photoresist is cured by baking.

  Then, using a relief printing apparatus 30 as shown in FIG. 2, ink of a hole injection material is applied onto the pixel electrode 3 by a relief printing method to form the hole injection layer 5. This relief printing apparatus 30 has a plate cylinder 38 on which a printing plate 37 provided with an ink tank 33, an ink chamber 34, an anilox roll 35, and relief printing is mounted. The ink tank 33 contains organic material ink, and the organic material ink is fed into the ink chamber 34 from the ink tank. The anilox roll 35 is rotatably supported in contact with the ink supply part of the ink chamber 34.

  As the anilox roll 35 rotates, the ink layer 39 of the organic material ink supplied to the surface of the anilox roll is formed with a uniform film thickness. The ink in this ink layer is transferred to the convex portion of the plate 37 mounted on the plate cylinder 38 that is driven to rotate in the vicinity of the anilox roll. A printing substrate 32 is installed on the stage 31, and the ink on the convex portion of the plate 37 is printed on the printing substrate 32, and an organic layer is formed on the printing substrate through a drying process as necessary. The

Next, after the hole transport layer 6 is formed, organic light emitting layers (red light emitting layer 7 and green light emitting layer 8) are similarly formed on the hole transport layer 6 by letterpress printing.
Next, after forming the organic light emitting layer by letterpress printing, the blue light emitting layer 10 is formed on the red light emitting layer 7, which is a light emitting region, the green light emitting layer 8, the hole transport layer 6, and the partition wall 4 which is a non light emitting region. Is formed by vacuum evaporation such as resistance heating evaporation.

  When the blue light emitting layer 10 is formed by vacuum deposition, the blue light emitting layer 10 contains an electron transporting host material and a hole transporting dopant material, and the concentration of the hole transporting dopant material in the blue light emitting layer is the counter electrode. The deposition rate is adjusted as the deposition progresses so that the co-deposition ratio of the electron transporting host material and the hole transporting dopant is gradually reduced from the 12 side toward the pixel electrode side 3.

Subsequently, the electron transport layer 11 and the counter electrode 12 are formed by vapor deposition on the blue light emitting layer 10 by vapor deposition such as resistance heating vapor deposition. Finally, in order to protect the pixel electrode 3, the organic light emitting medium layer, and the counter electrode 12 from oxygen and moisture in the air, the resin layer 13 is filled, covered with a sealing substrate 14, and sealed for organic light emitting display. The apparatus 1 is manufactured.
According to the organic light emitting display device 1 configured as described above and the manufacturing method thereof, the concentration of the hole transporting dopant material in the blue light emitting layer is gradually decreased from the counter electrode side to the pixel electrode side. The carrier movement from the red and green light emitting layers to the blue light emitting layer is suppressed. As a result, light emission of the blue light emitting layer is suppressed, and a decrease in color purity due to the influence from the blue light emitting layer in the red organic EL element and the green organic EL element can be suppressed.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention. For example, a hole blocking layer, an electron injection layer, or an electron blocking layer may be formed. Here, in the same manner as the hole transport layer 6, the electron blocking layer advances the holes from the pixel electrode 3 that is the pixel electrode toward the counter electrode 12 that is the counter electrode, and passes the holes, but the electrons are in the pixel. It has a function of preventing the traveling in the direction of the electrode 3. The hole blocking layer, the electron transporting layer, and the electron injecting layer allow electrons to pass from the counter electrode 12 that is the counter electrode toward the pixel electrode 3 that is the pixel electrode while passing the electrons. It has the function to prevent progressing in the direction.

  Further, a thin film such as lithium fluoride or sodium fluoride may be provided between the counter electrode 12 and the organic light emitting medium layer. To pattern the counter electrode 12, a metal film, a ceramic film deposition mask, or the like can be used. Furthermore, although the partition 4 is formed between the pixel electrodes 3, the partition 4 may not be provided.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.
As shown in FIG. 1, a strip-like pixel electrode 3 having a width of 80 μm and a thickness of 0.15 μm is formed on a light-transmitting substrate 2 (white plate glass: length 100 mm × width 100 mm × thickness 0.7 mm) by a sputtering method to 80 μm. Formed at intervals. Here, the surface roughness Ra of the pixel electrode 3 was 20 nm in an arbitrary plane having an area of 200 μm ² . The partition 4 has a lower end width of 90 μm, an upper end width of 45 μm, and a height of 2 μm in contact with the translucent substrate 2, and has a substantially trapezoidal cross section.

Here, the partition 4 was spin-coated with positive photosensitive polyimide, and as a condition for spin coating, the light-transmitting substrate 2 was rotated at 110 rpm for 5 seconds and then rotated at 400 rpm for 20 seconds. A photomask hidden only on the partition wall 4 was prepared, and a portion other than the partition wall 4 of the photosensitive material applied to the entire surface of the substrate by photolithography was exposed to 180 mJ / cm ² by an i-line stepper. After exposure, development was performed, and baking was performed at 200 ° C. for 60 minutes using an oven to form partition walls 4. Further, the hole injection layer 5 is applied to the partition walls by a relief printing method using a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid as a hole injection material, and this is applied at 200 ° C. Formed by drying for 30 minutes. The hole transport layer 6 uses a polyarylene derivative as a hole transport material, is dissolved in xylene, and an ink having a concentration of 3.0% by weight is applied to the partition wall by a relief printing method. It was formed by drying at 10 ° C. for 10 minutes.

  2,2 ', 2 "-(1,3,5-benzenetriyl) tris (1-phenyl-1H-benzimidazole) (TPBi) is used as the host material for the red organic light emitting layer, and 2,3' is used as the doped material. , 7,8,12,13,17,18-octaethyl-21H, 23H-Polyphyrin Platinum 2 (PtOEP) so that the weight ratio is 1% at TPBi / PtOEP = 0.90 / 0.10. The organic light-emitting ink dissolved in toluene was applied to the partition walls by letterpress printing and formed by drying for 10 minutes at 100 ° C. The thickness of the organic light-emitting layer after drying was 50 nm at the center of the pixel. became.

TPBi is used as the host material of the green organic light emitting layer, and tris (2- (p-tolyl) pyridine) iridium III (Ir (mppy) 3) is used as the doping material, so that the weight ratio is TPBi / Ir (mppy) 3 = 0. An organic light-emitting ink dissolved in toluene so as to have a concentration of 1% at .94 / 0.06 was applied to the partition walls by letterpress printing. This was formed by drying at 100 ° C. for 10 minutes. The thickness of the dried organic light emitting layer was 50 nm at the center of the pixel.
As the blue light-emitting layer host layer 9, the red light-emitting layer 7, the green light-emitting layer 8, and the hole transport layer 6 on which the light-emitting layers 7 and 8 are not formed are formed by vacuum evaporation, using 9, 10-di- (2 -Naphthyl) anthracene (hereinafter referred to as "DNA") was formed to a thickness of 10 nm at a film formation rate of 0.01 nm / sec.

As the blue light emitting layer 10, 9,10-di- (2-naphthyl) anthracene (hereinafter referred to as “DNA”) is formed on the red light emitting layer 7, the green light emitting layer 8, and the hole transport layer 6 by vacuum deposition. The deposition rate of 2,5,8,11-tetra-t-butylperylene (hereinafter referred to as “TBP”) was set at 0.5 nm / sec and 0 so that the deposition rate ratio of DNA and TBP was constant at 5%. The film was simultaneously formed while adjusting to 0.025 nm / sec to form a mixed film having a thickness of 30 nm.
Further, a thickness of 20 nm was formed on the blue light emitting layer 10 by a vacuum deposition method using Alq3 as the electron transport layer 11 at a film formation rate of 0.01 nm / sec. Thereafter, LiF / Al = 0.5 nm / 150 nm was formed as the counter electrode 12 by vapor deposition. Thereafter, the sealing substrate was bonded to obtain the organic light emitting display device 1.

In the peripheral portion of the display unit of the organic light emitting display device thus obtained, an anode-side extraction electrode connected to each pixel electrode and a cathode-side extraction electrode connected to the cathode layer are provided. ing. These extraction electrodes were connected to a power source, the organic light emitting display device was turned on and displayed, and the lighting state and the display state were confirmed.
When the obtained organic light emitting display device was driven and the display was confirmed, the light emission state was good. In addition, a decrease in color purity due to the influence from the blue light emitting layer in the red and green pixels was suppressed, and the display characteristics were good.

[Comparative Example 1]
First, the red light emitting layer and the green light emitting layer are formed by the same method as in the above embodiment, and the blue light emitting layer has a constant 5% co-evaporation rate of DNA and TBP without forming the blue light emitting layer host layer. The organic light emitting display device was obtained from the electron transport layer by the same method as in the above example.

When the organic light emitting display device of the comparative example thus obtained was driven, a decrease in color purity due to the influence from the blue light emitting layer was observed in the red pixel and the green pixel. Therefore, the display characteristics as an organic light emitting display device have been degraded.
From the evaluation result of the comparative example 1, since there was no blue light emitting layer host layer, the light emission of the blue light emitting layer in a red pixel and a green pixel was not suppressed, and color purity fell. In the examples, the presence of the blue light-emitting layer host layer provided an organic light-emitting display device having red pixels and green pixels, good color purity, and good display characteristics.

  The present invention relates to an organic EL display device in which a blue light emitting layer is laminated by a vapor deposition method on a red and green light emitting layer formed by a wet method, and the red organic EL element and the green organic EL element from the blue light emitting layer. This is useful in suppressing a decrease in color purity due to influence.

DESCRIPTION OF SYMBOLS 1 ... Organic light-emitting display device 2 ... Translucent substrate 3 ... Pixel electrode 4 ... Partition wall 5 ... Hole injection layer 6 ... Hole transport layer 7 ... Red light emitting layer 8 ... Green light emitting layer 9 ... Blue light emitting layer host layer 10 ... Blue light emitting layer 11 ... electron transport layer 12 ... counter electrode 13 ... resin layer 14 ... sealing substrate 30 ... letterpress printing device 31 ... stage 32 ... substrate to be printed 33 ... ink tank 34 ... ink chamber 35 ... anilox roll 36 ... doctor 37 ... letterpress 38 ... plate cylinder 39 ... ink layer

Claims (5)

A substrate,
A plurality of pixel electrodes provided for each of the red organic EL element, the green organic EL element, and the blue organic EL element on the substrate,
A hole injection / transport layer having at least one of the characteristics of hole injection or hole transport formed on the pixel electrode;
A red light emitting layer formed on the pixel electrode for the red organic EL element with the hole injection / transport layer interposed therebetween;
A green light emitting layer formed on the pixel electrode for the green organic EL element with the hole injection / transport layer interposed therebetween;
A blue light emitting layer host layer formed on at least the hole injecting / transporting layer where the light emitting layer is not formed, the red light emitting layer, and the green light emitting layer;
A blue light emitting layer formed on the entire surface of the blue light emitting layer host layer and containing at least a host material of the blue light emitting layer host layer and a hole transporting blue dopant material;
An electron injection / transport layer formed on the entire surface of the blue light emitting layer and having at least one of electron injection and electron transport properties;
An organic EL display device comprising: a counter electrode formed on the electron injection / transport layer.   2. The organic EL display device according to claim 1, wherein the blue light emitting layer host layer has a thickness of 5 nm to 15 nm.   3. The organic EL display device according to claim 1, wherein the blue light emitting layer host material has an electron transporting property. Forming each pixel electrode corresponding to each of a red organic EL element, a green organic EL element, and a blue organic EL element on a substrate;
Forming a hole injection / transport layer having at least one of the characteristics of hole injection or hole transport on the pixel electrode by a wet method;
Forming a red light emitting layer and a green light emitting layer on each pixel electrode for the red organic EL element and the green organic EL element by a wet method with the hole injection / transport layer interposed therebetween;
Forming a blue light emitting layer host layer on the hole injection / transport layer where the light emitting layer is not formed, the red light emitting layer, and the green light emitting layer over the entire surface by a vapor deposition method;
Forming the blue light-emitting layer on the entire surface of the blue light-emitting layer host layer by vapor deposition;
A step of sequentially forming an electron injection / transport layer and a counter electrode having at least one of electron injection or electron transport on the entire surface of the blue light emitting layer; and
A method for producing an organic EL display device, comprising:   5. The method for manufacturing an organic EL display device according to claim 4, wherein the formation of the light emitting layer is performed by coating, and inkjet, nozzle printing, letterpress printing, gravure printing, or reverse offset printing is used as the coating.

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