JP2013211169A - Organic electroluminescent display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent organic EL display panel that does not impair transparency even during non-emission.SOLUTION: A transparent organic EL display panel includes: a transparent first electrode 102 formed on a transparent substrate 101; a partition wall 103 that partitions a pixel region a by being formed on the upper surface of the transparent first electrode 102 on the opposite side of the transparent substrate 101; a luminescent medium layer 110 that is formed on the upper surface of the transparent first electrode 102 corresponding to the pixel region a, and includes at least an organic light-emitting layer; and a transparent second electrode 105 formed on the upper surface of the luminescent medium layer 110 on the opposite side of the transparent first electrode 102. The partition wall 103 has a side surface 103A located closer to the pixel region a. An angle Θ1 formed by an end portion of the side surface 103A contacted with the upper surface of the transparent first electrode 102 and the upper surface of the transparent first electrode 102 is not less than 2° nor more than 45°. An angle Θ2 formed by a plane parallel to the upper surface of the transparent first electrode 102 and the side surface 103A at a portion spaced away from the upper surface of the transparent first electrode 102 is always Θ2<Θ1.

Description

  The present invention relates to an organic electroluminescent display panel.

  In an organic electroluminescence element (hereinafter referred to as an organic EL element), an organic light emitting layer made of an organic light emitting material is formed between two opposing electrodes, and when voltage is applied between both electrodes, holes are transferred from the anode and electrons are transferred from the cathode. When injected, a current flows through the organic light emitting layer, and the holes and electrons recombine in the organic light emitting layer to emit light.

  In general, as a substrate for a display panel, a substrate in which patterned photosensitive polyimide is formed in a partition shape so as to partition light emitting pixels is used. At that time, the partition pattern is formed so as to cover the edge portion of the transparent electrode formed as an anode.

  In addition to the organic light emitting layer, a carrier injection layer (also called a carrier transport layer) is formed between the electrodes. The carrier injection layer controls the injection amount of electrons when injecting electrons from the electrode to the organic light emitting layer, or controls the injection amount of holes when holes are injected from the other electrode to the organic light emitting layer. A layer used to control and refers to a layer inserted between an electrode and an organic light emitting layer. As the electron injection layer, an electron transporting organic substance such as a metal complex of a quinolinol derivative or a relatively small work function such as Ca or Ba such as an alkali metal is used, or a plurality of layers having these functions are stacked. In some cases. As the hole injection layer, TPD (triphenyleneamine derivative: see Patent Document 1), PEDOT: PSS (mixture of polythiophene and polystyrenesulfonic acid: see Patent Document 2), or an inorganic hole transport material (Patent Document 3) See). In any case, it is necessary to obtain a high-performance organic EL display panel by inserting it between the electrode and the light-emitting layer in order to increase the luminous efficiency by controlling the injection amount of electrons and holes. It is.

  Next, there are two types of methods for forming a hole injection layer for injecting hole carriers: dry film formation and wet film formation methods. When wet film formation methods are used, they are generally dispersed in water. Polythiophene derivatives are used, but water-based inks are easily affected by the base and are difficult to coat uniformly. Recently, materials soluble in organic solvents have been developed. In contrast, dry film formation enables simple and uniform coating of the entire surface.

  Similarly, there are two methods for forming the organic light emitting layer: dry film formation and wet film formation. However, when using the vacuum evaporation method, which is dry film formation that facilitates uniform film formation, a fine pattern mask is used. Therefore, it is necessary to perform patterning, and large substrates and fine patterning are very difficult.

Therefore, recently, a method of forming a thin film using a wet film forming method by dissolving a polymer material in a solvent to form a coating liquid has been tried. When a light emitting medium layer including an organic light emitting layer is formed by a wet film formation method using a coating material of a polymer material, the layer structure is a hole injection layer, an interlayer or a hole transport layer from the anode side, an organic light emitting layer A three-layer structure is generally laminated. At this time, the organic light emitting layer is formed by dissolving or stably dispersing organic light emitting materials having respective emission colors of red (R), green (G), and blue (B) in a solvent in order to form a color panel. It can be applied separately using organic light emitting ink (see Patent Documents 4 and 5).
By using wet film formation, a mask with a fine pattern is not necessary, and a large substrate or a fine pattern can be easily formed.

  Ideally, it is possible to draw out performance by using different carrier injection layers for each of the RGB light emitting layers, but because the number of steps in the mass production process and high-definition patterning are difficult, The carrier injection layer is generally formed of a solid film common to RGB.

  By the way, the above-mentioned organic EL element has a feature that the thickness of the element is very thin. Taking advantage of this feature, a so-called double-sided light emitting type transparent organic EL element has been studied. A display that uses this is transparent when it is not emitting light, and emits light when an electric current is passed. It is a display panel featuring in-car monitors, transparency such as advertisements, watches, lighting, and televisions. It is attracting attention as. The transparent organic EL display has a visible light transmittance higher than that of a normal display, and the background can be seen through the display. For example, Patent Document 6 introduces a color display device in which transparent EL elements of three RGB colors are superimposed.

  As described above, in the transparent organic EL element, light emission performance is also important, but transparency when not emitting light is also important. The transparency required for the transparent organic EL device means that the in-plane transmittance is large and constant, and that the wiring and other patterns are not visible or difficult to see.

  In particular, metal composite oxidation such as ITO (indium tin composite oxide), indium zinc composite oxide, and zinc aluminum composite oxide, which are TFTs that are switching elements, anodes used in organic EL elements, and lead-out wirings for anodes Objects have a large refractive index and a large effect on transparency.

  In addition, transparency is also required for partitions of light emitting pixels and partition walls used as an insulating layer between electrodes. As the photosensitive material for forming the partition walls, in addition to polyimide, acrylic resin, novolac resin, fluorene, and the like are used, and are selected according to necessary transmittance and physical properties. However, even when a material having a high transmittance is used, there is a problem in that the end of the partition wall formation portion becomes conspicuous at the time of non-light emission due to the difference in the refractive index and the reflectance with the adjacent member and the shape, and the transparency is poor. there were.

JP 2001-93668 A JP 2001-155858 A Japanese Patent No. 2916098 Japanese Patent No. 2851185 JP-A-9-63771

  It was an object to provide a transparent organic EL display panel that does not impair the transparency even when it does not emit light.

  According to the first aspect of the present invention, the first partition electrode formed on the transparent substrate and the partition wall defining the pixel region a by being formed on the upper surface of the first transparent electrode opposite to the transparent substrate. A light emitting medium layer including at least an organic light emitting layer formed on an upper surface of the transparent first electrode corresponding to the pixel region a, and an upper surface of the light emitting medium layer opposite to the transparent first electrode. A transparent organic electroluminescence display panel comprising a transparent second electrode, wherein the partition wall has a side surface located on the pixel region side and is in contact with the upper surface of the transparent first electrode. The angle Θ1 formed by the portion and the upper surface of the transparent first electrode is not less than 2 ° and not more than 45 °, and is parallel to the upper surface of the transparent first electrode at a location away from the upper surface of the transparent first electrode. The angle Θ2 formed by the side surface is always Θ 2 <Θ1.

  According to a second aspect of the present invention, in the transparent organic electroluminescent display panel according to the first aspect, a height h of the partition wall is 0.2 μm or more and 2 μm or less.

  The invention described in claim 3 is the transparent organic electroluminescence display panel according to claim 1 or 2, wherein the visible light transmittance of the display region b of the transparent organic EL display is 60% or more. .

  The angle Θ1 formed by the end of the side surface that contacts the top surface of the transparent first electrode and the top surface of the transparent first electrode is 2 ° or more and 45 ° or less, and is transparent at a position away from the top surface of the transparent first electrode. When the angle Θ2 formed by the side surface with respect to the plane parallel to the upper surface of one electrode is always Θ2 <Θ1, changes in the transmittance and refractive index of the partition wall are moderated, visibility is low, and transparency is improved. This is advantageous in providing a transparent organic EL display panel that does not impair the transparency even when no light is emitted.

Explanation plane schematic diagram of an example of the transparent organic EL display panel of the present invention Description cross-sectional schematic diagram of an example of the transparent organic EL display panel of the present invention Description cross-sectional schematic diagram of an example of the transparent organic EL display panel of the present invention Schematic diagram of letterpress printer Example of the present invention, comparative partition formation conditions and formed partition shape

FIG. 1 shows a schematic plan view of a passive matrix driving type organic EL display panel as one embodiment of the present invention, and FIG. 2 shows a schematic sectional view of AA ′ described in FIG.
The organic EL display panel of the present invention has a transparent first electrode 102 formed on a substrate 101 as an anode and a transparent second electrode 105 formed so as to face the cathode as a cathode, and a layer sandwiched between the layers (light emission) Media layer 110).

  The transparent first electrode 102 is formed as a pixel electrode in the pixel region a partitioned by the partition wall 103 for each pixel, and the transparent second electrode 105 is formed as a counter electrode on the pixel region. In the light emitting medium layer, at least an organic light emitting layer 113 that contributes to light emission, a hole injection layer 111 as a carrier injection layer for injecting holes, a hole transport layer 112 as a carrier injection layer for transporting holes, and electrons are injected. An electron injection layer 114 is included as a carrier injection layer.

  The light emitting medium layer 110 requires a carrier injection layer such as an electron transport layer or a hole blocking layer (interlayer) between the cathode and the light emitting layer, and an electron blocking layer (interlayer) between the anode and the light emitting layer. Depending on the case, it can be appropriately laminated.

  Outside the pixel region a, an anode extraction substrate wiring 104 and a cathode extraction substrate wiring 106 for connection to an external drive circuit are provided. In the present invention, the anode 102 and the anode lead-out substrate wiring 104 and the cathode 105 and the cathode lead-out substrate wiring 106 are common to each other as a method that can be easily manufactured. However, a contact portion is provided and relayed by, for example, an external lead electrode having low resistance. You may do it.

The partition wall 103 is provided to partition the light emitting pixels in the pixel region a, but may be formed so as to cover the entire display region b in order to keep the transmittance of the entire display region b constant. In order to increase the transparency of the display, it is preferable to use a material having a high transmittance, and it is preferable to use a material having a thickness of 1 μm and a visible light transmittance of 60% or more.
Further, the angle Θ1 (FIG. 3) between the pixel region a and the partition wall end where the partition wall 103 is in contact is preferably small, preferably 45 ° or less, and more preferably 30 ° or less. The smaller the difference in refractive index and reflectance between adjacent members and the slower the change, the lower the visibility and the better the transparency.
Further, the height h (FIG. 3) of the partition wall 103 is preferably 2 μm or less, and more preferably 1 μm or less. The thinner the film thickness, the higher the transmittance, and the smaller the difference in refractive index and reflectance between adjacent members, and the slower the change, the lower the visibility and the better the transparency.

  The hole injection layer 111 is patterned in the pixel region a, but may cover the entire display region b. By covering the entire surface, the film shape in the pixel region becomes flat, and the film thickness for each pixel can be made uniform.

  Although the hole transport layer 112 is patterned only in the pixel region a on the hole injection layer 111, the entire pixel region b may be covered in the same manner as the hole injection layer 111.

The organic light emitting layer 113 can be formed without being mixed with the pixel region a due to the shape of the partition wall 103. Further, it may be formed between adjacent pixels so as not to mix colors.
Furthermore, an organic EL display panel can be obtained by arranging the organic EL elements as pixels (subpixels). In other words, a full-color organic EL display panel can be manufactured by coating the organic light-emitting layer 113 constituting each pixel with, for example, three colors RGB without mixing colors.

  The electron injection layer 114 is formed in the pixel region a on the organic light emitting layer 113, but may cover the entire display region b, and may have the same pattern as the transparent second electrode 105.

  In other words, the transparent organic electroluminescence display panel is formed on the upper surface of the transparent first electrode 102 formed on the transparent substrate 101 and the transparent first electrode 102 on the side opposite to the transparent substrate 101, thereby forming a pixel region. a light-emitting medium layer 110 including at least an organic light-emitting layer formed on the upper surface of the transparent first electrode 102 corresponding to the pixel region a, and a light-emitting medium layer 110 opposite to the transparent first electrode 102. And a transparent second electrode 105 formed on the upper surface of the substrate.

<Transparent substrate>
Any material can be used as the transparent substrate 101 as long as it has transparency, mechanical strength and insulation and is 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 In addition, a transparent base material in which a polymer resin film such as a silicone resin or a polyester resin is single-layered or laminated can be used.

  Further, in order to avoid moisture intrusion into the organic EL display panel, it is preferable that an inorganic film is formed or a fluorine resin is applied to perform moistureproof treatment or hydrophobic treatment. In particular, in order to avoid intrusion of moisture into the light emitting medium layer, it is preferable to reduce the moisture content and gas permeability coefficient in the substrate.

<Transparent first electrode>
A transparent first electrode 102 is formed on the transparent substrate 101, and patterning is performed as necessary. In the present invention, the transparent first electrode 102 is partitioned by the partition wall 103 and becomes the transparent first electrode corresponding to each pixel region a.
As the material of the transparent first electrode, metal composite oxides such as ITO (indium tin composite oxide), indium zinc composite oxide, zinc aluminum composite oxide, metal oxides such as gold and platinum, and fine particles of metal materials Either a single layer or a laminate of a fine particle dispersion film in which is dispersed in an epoxy resin or an acrylic resin can be used.

  When the transparent first electrode 102 is used as an anode, it is preferable to select a material having a high work function such as ITO. As a method of forming the transparent first electrode, 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 of the pixel electrode, 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 a material and a film forming method.

<Substrate wiring for anode removal>
The anode lead-out substrate wiring 104 is preferably the same material as that of the transparent first electrode 102. However, in order to maintain transparency in the display area b and reduce the influence of wiring resistance, The contact portion may be provided, and a metal material such as Cu or Al may be provided as an auxiliary electrode.
As a method for forming the substrate wiring 104 for extracting the anode, 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, or a gravure printing method is used. Further, a wet film forming method such as a screen printing method can be used. As a patterning method for the extraction substrate wiring, 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.

<Partition wall>
After the transparent first electrode 102 and the anode lead-out substrate wiring 104 are formed, the partition wall 103 is formed.

  The photosensitive material for forming the partition wall 103 may be either a positive type resist or a negative type resist, and may be a commercially available one, but it needs to have insulating properties. In the case where the partition 103 does not have sufficient insulating properties, a current flows to the adjacent pixel electrode through the partition 103 and a display defect occurs. In addition, high transparency in the visible light region is also required for transparent organic EL displays. A material having a transmittance of 1 μm in the visible light region and a thickness of 60% or more is preferable. Specific examples include polyimide, acrylic resin, novolac resin, and fluorene, but the present invention is not limited thereto.

  The photosensitive material for forming the partition wall 103 is applied using a known coating method such as a spin coater, bar coater, roll coater, die coater, or gravure coater. Next, in the step of pattern exposure and development to form the partition wall pattern, the partition wall pattern can be formed by a conventionally known exposure and development method. The shape of the partition wall can be adjusted by changing the exposure condition and the development condition. Regarding firing, firing can be performed by a conventionally known method using an oven, a hot plate or the like.

  The partition wall 103 of the present invention is formed so as to partition the pixel region a corresponding to the light emitting pixel. By providing the partition wall 103 between adjacent pixel electrodes, the spreading of the luminescent medium layer ink printed on each pixel electrode can be suppressed, and color mixing can be suppressed. The occurrence of a short circuit from the end of one electrode 102 can be prevented. Further, if the display area b is formed so as to cover the entire surface, the transmittance of the entire display area b can be made constant and the transparency can be improved.

  The height h of the partition wall 103 is preferably in the range of 0.2 μm to 3.0 μm, and more preferably in the range of 0.2 μm to 1 μm. If the height h of the partition wall 103 is less than 0.2 μm, the effect of preventing a short circuit cannot be obtained, or the adjacent pixels are mixed in color when the light emitting medium layer is formed. If the height h of the partition wall 103 exceeds 3.0 μm, the transparent second electrode 105 may be disconnected when the transparent second electrode 105 is formed, resulting in display failure, hindering sealing, or the transparency of the partition wall 103. This causes problems such as lowering the performance. Further, by reducing the thickness, the transmittance can be kept high, the change in the transmittance and the refractive index can be reduced, and the visibility can be lowered and the transparency can be improved.

The angle Θ1 between the pixel region a on the transparent first electrode 102 and the partition wall end where the partition wall 103 is in contact is preferably 2 ° or more and 45 ° or less, and more preferably 30 ° or less. When the angle exceeds 45 °, the transmittance and the refractive index of the transparent first electrode 102 and the partition wall 103 in the pixel region a change rapidly, and the end of the partition wall 103 is noticeable and the transparency is deteriorated. By reducing the angle, changes in transmittance and refractive index become gradual, visibility is low, and transparency can be improved. However, if it is less than 2 °, it becomes difficult to manufacture.
In addition, since the angle Θ2 of the partition wall surface is always Θ2 <Θ1 with respect to the plane parallel to the pixel region a, the partition wall shape is gentle, the change in transmittance is gentle, the visibility is low, and the transparency is good. .
More specifically, as shown in FIG. 3, the partition wall 103 has a side surface 103A located on the pixel region a side.
An angle Θ <b> 1 formed by the end of the side surface 103 </ b> A that contacts the upper surface of the transparent first electrode 102 and the upper surface of the transparent first electrode 102 is 2 ° or more and 45 ° or less.
In addition, an angle Θ2 formed by the side surface 103A with respect to a plane parallel to the upper surface of the transparent first electrode 102 at a location away from the upper surface of the transparent first electrode 102 is always Θ2 <Θ1. More specifically, the angle Θ2 formed by the side surface 103A with respect to the plane parallel to the top surface of the transparent first electrode 102 in the intermediate portion in the height direction of the partition wall 103A is always Θ2 <Θ1.

<Hole injection layer>
The material of the hole injection layer 111 is arbitrary, but the resistivity is preferably 10 ⁴ Ω · cm or more in order to prevent a short circuit between pixels. Further, by providing a step in the shape of the partition wall, the film thickness of the hole injection layer may be changed to suppress a short circuit between pixels. For example, Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeOx, NiO, CoO, Pr ₂ O ₃ , Ag ₂ O, MoO ₂ , Bi ₂ O ₃ , ZnO, TiO ₂ , SnO ₂ , ThO ₂ , Transition metal oxides such as V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO _{2 and the} like, inorganic compounds containing one or more of these nitrides and sulfides, polyaniline derivatives, oligos Aniline derivative, quinonediimine derivative, polythiophene derivative, polyvinylcarbazole (PVK) derivative, poly (3,4-ethylenedioxythiophene) (PEDOT), pyrrole derivative, aromatic amine, (triphenylamine) dimer derivative (TPD), ( α-naphthyldiphenylamine) dimer (α-NPD), [(triphenylamine) dimer] Triarylamines such as Rhodimer (Spiro-TAD), 4,4 ′, 4 ″ -tris [3-methylphenyl (phenyl) amino] triphenylamine (m-MTDATA), 4,4 ′, 4 ″ -Starburst amines such as tris [1-naphthyl (phenyl) amino] triphenylamine (1-TNATA) and 5,5′-α-bis- {4- [bis (4-methylphenyl) amino] phenyl} -2,2 ': 5', 2'-α-terthiophene (BMA-3T), oligothiophenes, aromatic amine-containing polymers, aromatic diamine-containing polymers, fluorene-containing aromatic amine polymers, triazoles Organic materials such as oxazole, oxadiazole, silole, and boron.

  As a method for forming the hole injection layer 111, depending on the material, a dry film forming method such as a resistance heating evaporation method, an electron beam evaporation method, a reactive evaporation method, an ion plating method, a sputtering method, a spin coating method, Existing film forming methods such as a sol-gel method, an ink jet method, a nozzle printing method, a relief printing method, a slit coating method, a wet coating method such as a bar coating method can be used. Various film forming methods can be used.

  The thickness of the hole injection layer 111 is preferably 2 nm or more and 100 nm or less. When the thickness is smaller than 2 nm, short defects are likely to occur, and when the thickness is 100 nm or more, the resistance is increased and the current is decreased.

  Inorganic materials are preferred because many materials are excellent in heat resistance and electrochemical stability. These can be formed as a single layer or a stacked structure of a plurality of layers, or a mixed layer.

<Interlayer>
After forming the hole injection layer, an interlayer can be formed. In this case, the hole transport layer 112 is patterned in a line on the hole injection layer 111 formed on the entire surface, but an interlayer may be formed on the hole injection layer 111 on the entire surface.

  Materials used as an interlayer include polyaniline derivatives, oligoaniline derivatives, quinonediimine derivatives, polythiophene derivatives, polyvinylcarbazole (PVK) derivatives, poly (3,4-ethylenedioxythiophene) (PEDOT), pyrrole derivatives, aromatic amines, ( Triarylamines such as (triphenylamine) dimer derivative (TPD), (α-naphthyldiphenylamine) dimer (α-NPD), [(triphenylamine) dimer] spiro-dimer (Spiro-TAD), 4,4 ′, 4 ″ -tris [3-methylphenyl (phenyl) amino] triphenylamine (m-MTDATA), 4,4 ′, 4 ″ -tris [1-naphthyl (phenyl) amino] triphenylamine (1-TNATA ) And other starburst amines and 5,5′-α -Bis- {4- [bis (4-methylphenyl) amino] phenyl} -2,2 ′: 5 ′, 2′-α-terthiophene (BMA-3T) and other oligothiophenes, aromatic amine-containing high Examples include molecules, aromatic diamine-containing polymers, fluorene-containing aromatic amine polymers, triazole-based, oxazole-based, oxadiazole-based, silole-based, and boron-based organic materials.

  As a method for forming an interlayer, depending on the material, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a dry film formation method such as a sputtering method, a spin coating method, a sol-gel method, Existing film forming methods such as an ink jet method, a nozzle printing method, a relief printing method, a slit coating method, and a wet film forming method such as a bar coating method can be used. Can be used.

<Organic light emitting layer>
After the hole transport layer 112 is formed, the organic light emitting layer 113 is formed. The organic light emitting layer 113 is a layer that emits light by recombining holes and electrons. When the display light emitted from the organic light emitting layer 113 is monochromatic, it is formed so as to cover the hole transport layer 112. In order to obtain multicolor display light, it can be suitably used by patterning as necessary.

  Examples of the organic light-emitting material forming the organic light-emitting layer 113 include coumarin-based, perylene-based, pyran-based, anthrone-based, porphyrin-based, quinacridone-based, N, N′-dialkyl-substituted quinacridone-based, naphthalimide-based, N, N′-. Diaryl-substituted pyrrolopyrrole, iridium complex, and other luminescent dyes dispersed in polymers such as polystyrene, polymethyl methacrylate, polyvinylcarbazole, and polyarylene, polyarylene vinylene, and polyfluorene polymers Examples of the material include, but are not limited to, the present invention.

  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 polymer materials described above, 9,10-diarylanthracene derivatives, pyrene, coronene, perylene, rubrene, 1,1,4,4-tetraphenylbutadiene, tris (8-quinolato) 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-quinolate) 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-quino) Norato) scandium complex, bis [8- (para-tosyl) aminoquinoline] zinc complex and cadmium complex, 1,2,3,4-tetraphenylcyclopentadiene, poly-2,5-diheptyloxy-para-phenylene vinylene A low molecular weight light emitting material such as can be used.

As a method for forming the organic light emitting layer 113, an existing film forming method such as an ink jet printing method, a nozzle print printing method, a relief printing method, a gravure printing method, or a wet film forming method such as a screen printing method is used depending on the material. Although the present invention is not limited to these,
In particular, when an organic light emitting material is dissolved or stably dispersed in a solvent and an organic light emitting ink is used to coat the light emitting layer in each light emitting color, an ink jet method, a nozzle print method, and the like that can transfer and pattern ink between partition walls, A relief printing method is preferred.

<Method for forming luminescent medium layer>
A case where the light emitting medium layer is formed by a relief printing method is shown below.
FIG. 4 shows a schematic diagram of a relief printing apparatus 600 when pattern printing is performed on an organic light emitting ink made of an organic light emitting material on a substrate 602 on which a pixel electrode, a hole injection layer, and a hole transport layer are formed. .
This manufacturing apparatus has a plate copper 608 on which an ink tank 603, an ink chamber 604, an anilox roll 605, and a plate 607 provided with a relief plate are mounted. The ink tank 603 contains organic light emitting ink diluted with a solvent, and the organic light emitting ink is fed into the ink chamber 604 from the ink tank. The anilox roll 605 is instructed to rotate in contact with the ink supply unit of the ink chamber 604.

  As the anilox roll 605 rotates, the ink layer 609 of the organic light-emitting ink supplied to the anilox roll surface is formed with a uniform film thickness. The ink in this ink layer is transferred to the convex portion of the plate 607 mounted on the plate cylinder 608 that is driven to rotate in the vicinity of the anilox roll. A printing substrate 602 is installed on the stage 601, and the ink on the convex portion of the plate 607 is printed on the printing substrate 602, and if necessary, an organic light emitting layer is formed on the printing substrate through a drying process. Is done.

  The other light emitting medium layer can be formed by using the above-mentioned forming method in the same manner when it is applied as an ink.

<Electron injection layer>
After the organic light emitting layer 113 is formed, the electron injection layer 114 can be formed. Materials used for the electron injecting layer include triazole-based, oxazole-based, oxadiazole-based, silole-based, boron-based and other low molecular materials, lithium fluoride, lithium oxide, sodium fluoride, and other alkali metals, and Ba, Ca It is possible to form a film by a vacuum deposition method using an alkaline earth metal salt such as an oxide or the like.

<Transparent second electrode>
Next, the transparent second electrode 106 is formed. The material and forming method of the transparent second electrode 106 are the same as those of the transparent first electrode 102. However, when the transparent second electrode 106 is a cathode, the work function is high in the efficiency of electron injection into the organic light emitting layer 113. Use a low substance.
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 layer, 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, Al An alloy system with a metal element such as Cu or Cu may be used. Specifically, an alloy such as MgAg, AlLi, or CuLi can be used, but any of them needs to be a very thin film of 10 nm or less in order to obtain transparency. A transparent conductive film such as a metal composite oxide such as ITO (indium tin composite oxide), IZO (indium zinc composite oxide), or AZO (zinc aluminum composite oxide) can be used. As the forming method, depending on the material, dry film forming methods such as resistance heating evaporation method, electron beam evaporation method, reactive evaporation method, ion plating method, sputtering method, ink jet printing method, gravure printing method, screen printing, etc. Existing film forming methods such as a wet film forming method such as a nozzle coating method can be used, but the present invention is not limited to these.

  As an organic EL display panel, it is possible to emit light by sandwiching a light emitting material between electrodes and passing an electric current. However, since an organic light emitting material is easily degraded by moisture and oxygen in the atmosphere, A protective layer 108 and a sealing body 109 for blocking are provided.

<Protective layer>
The protective layer 108 may be any material as long as it has a high barrier property such as low permeability to moisture and oxygen in the atmosphere, and has a high transmittance and high transparency, but carbon-containing silicon nitride (SiNxCy) is preferred. . In particular, a film in which the carbon content in the protective layer continuously changes is used. By changing the amount of carbon, a film with a high carbon content is soft and becomes a film with excellent coverage and adhesion, and a film with a low carbon content is a film with high density and high barrier properties. The amount of carbon is preferably such that the ratio of the amounts of carbon is less than 1.0 when Si is 1. This is because if the carbon content is 1.0 or more, the film may be colored or become brittle. It is preferable that the layer in which the composition changes is repeated a plurality of times. By repeating a plurality of times, it is possible to cover protrusions that could not be covered by only one layer, and to reduce the cracks generated in the first layer, so that a film having higher barrier properties can be obtained.

In a preferred embodiment of the present invention, the amounts of nitrogen and carbon contained in the carbon-containing silicon nitride (SiNxCy) constituting the protective layer 108 are 1.0 ≦ x ≦ 1.4, 0.2 ≦ y ≦ 0. 4 and a layer in a range of 0.4 ≦ x <1.0 and 0.4 <y <1.0 are preferably provided.
With this configuration, it is possible to achieve both stress relaxation, adhesion to the substrate surface, and good gas barrier characteristics, and to improve the protection characteristics of the element.

When the carbon-containing silicon nitride (SiNxCy) 2 is formed, a plasma CVD method is used. In the plasma CVD method, all reactions that generate film-forming species are performed in the gas phase, so that it is not necessary to cause a reaction on the substrate surface, and is the most suitable film-forming method for low-temperature film formation.
As an example of a method for continuously changing the amount of carbon in the protective layer 108, there is a method in which a plasma CVD method is performed using an organic silicon compound, one or both of ammonia and nitrogen, and hydrogen as source gases. It is done. For example, the amount of carbon in the film can be reduced by increasing the applied power.
Further, there is a method in which one of or both of silane, ammonia and nitrogen, hydrogen, and a carbon-containing gas is used as a raw material gas, and a plasma CVD method is performed while changing the concentration of the carbon-containing gas. In this case, the composition can be controlled by changing the flow rate of the carbon-containing gas during film formation. In addition, it is desirable to adjust appropriately according to parameters such as the film forming substrate temperature and gas pressure.

Examples of the organic silicon compound include trisdimethylaminosilane (TDMAS), hexamethyldisilazane (HMDS), hexamethyldisiloxane (HMDSO), and tetramethyldisilazane (TMDS). Examples of the carbon-containing gas include methane, ethylene, propene and the like.
The thickness of each layer of the protective layer 108 is not particularly limited, but is preferably about 100 to 500 nm, and the whole should be about 1000 nm. Within this range, defects such as pinholes in the film itself can be compensated, and the barrier property against intrusion of oxygen and moisture is greatly improved. Furthermore, the film can be formed in a short time, and the light extraction from the organic light emitting layer 113 is not hindered. Further, if the carbon content is large on the cathode 103 side and is changed less as the distance from the cathode 103 increases, it is expected that the adhesion and covering properties are further improved.

<Sealing body>
Next, the sealing body 109 is attached to the protective layer 108 described above. By sticking the sealing body 109, not only the barrier property is further improved, but also resistance to mechanical damage that cannot be obtained only by the protective layer 108 described above can be obtained. For example, a resin layer can be provided over the sealing body 109.

The sealing body 109 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, quartz, 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.

  When the sealing body 109 is bonded, an adhesive may be uniformly applied to the sealing body 109 side, or may be applied so as to surround the periphery. Alternatively, a method of thermally transferring the adhesive layer formed in a sheet shape may be used. The adhesive layer is made of epoxy resin, acrylic resin, silicone resin, photo-curing adhesive resin, thermosetting adhesive resin, two-part curable adhesive resin, and acid-modified products such as polyethylene and polypropylene. A thermoplastic adhesive resin made of, for example, can be used as a single layer or laminated. In particular, it is desirable to use an epoxy thermosetting adhesive resin that is excellent in moisture resistance and water resistance and has little shrinkage upon curing. In addition, in order to remove moisture contained in the adhesive layer to the extent that it does not interfere with the light transmission of the adhesive layer, a desiccant such as barium oxide or calcium oxide is mixed in, or a few percent to control the thickness of the adhesive layer. Inorganic fillers may be mixed.

  Bonding is performed with the sealing body 109 with the adhesive thus prepared, and curing processing is performed for each. Although this series of protective layer forming processes is desirably performed in a nitrogen atmosphere, there is no significant effect even in the air for a short time after the protective layer 108 is formed.

  As an example of the material of the resin layer on the sealing body 109, 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, Acrylic resins such as ethylene ethyl acrylate (EEA) polymer, 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 Can be mentioned. As an example of a method for forming a resin layer on the sealing body 109, 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 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 body is arbitrarily determined by the magnitude | size and shape of the organic electroluminescent display panel to seal, about 5-500 micrometers is desirable. Although the resin layer is formed on the sealing body 109 here, it can be formed directly on the organic EL display panel side.

[Example 1]
Examples of the present invention will be described below.
5 shows numerical values of the gap, the exposure amount, the development time, the partition wall height L, and the angle Θ1 of the partition wall 103 in Examples 1 to 4 and the comparative example.
Non-alkali glass OA-10 manufactured by Nippon Electric Glass Co., Ltd. was prepared as a transparent substrate. The size of the substrate is 200 mm × 200 mm, in which 5 inches diagonal is arranged, and a display display unit is arranged in the center.

  This substrate is placed in a sputtering film forming apparatus in which ITO (indium tin oxide) is placed, and ITO is formed on the entire surface so as to have a thickness of 50 nm.

  Next, a TFR790PL positive resist made by Nippon Ohka Co., Ltd. was formed on the entire surface of the substrate with a spin coater to a thickness of 2 μm, and then the anode and anode lead-out wiring were left by photolithography, and wet etching was performed with an aqueous ferric chloride solution. A lead-out wiring was formed.

Next, partition walls are formed by photolithography to partition the pixel region and the anode contact portion.
An acrylic positive photosensitive material with a thickness of 1 μm was formed on the entire surface of the glass substrate on which the anode and anode lead-out wiring were formed.
Next, the photosensitive material applied on the entire surface was exposed using a photomask with a gap of 100 μm and an exposure amount of 200 mJ. Thereafter, the film was immersed in a developing solution for 40 s to remove the exposed portion, and then post-baked.
The height of the formed partition wall was 1 μm, the angle Θ1 between the pixel region a and the end of the partition wall was 30 °, and the angle Θ2 of the partition wall surface with respect to the plane parallel to the pixel region a was always Θ2 <Θ1.

  After that, using an ink in which a polyfluorene derivative, which is a hole injection material, is dissolved in anisole so as to have a concentration of 1.0%, this substrate is set in a printing machine and directly above a pixel portion sandwiched between partition walls. Printing was performed by letterpress printing according to the line pattern. At this time, an anilox roll of 300 lines / inch and a photosensitive resin plate were used. The thickness of the hole injection layer after printing and drying was 40 nm.

  After that, this substrate was set in a printing machine using an ink in which polyvinylcarbazole derivative as an interlayer material was dissolved in toluene so as to have a concentration of 0.5%, and the substrate was directly above the pixel electrode sandwiched between insulating layers. Printing was performed by letterpress printing according to the line pattern. At this time, an anilox roll of 300 lines / inch and a photosensitive resin plate were used. The film thickness of the interlayer after printing and drying was 20 nm.

  Next, using organic light-emitting ink in which polyphenylene vinylene derivative, which is an organic light-emitting material, is dissolved in toluene to a concentration of 1%, this substrate is set in a printing machine and directly above the pixel electrode sandwiched between insulating layers. The organic light emitting layer was printed by a relief printing method according to the line pattern. At this time, an anilox roll of 150 lines / inch and a photosensitive resin plate corresponding to the pixel pitch were used. The thickness of the organic light emitting layer after printing and drying was 80 nm. This process was repeated three times in total to form an organic light emitting layer corresponding to the emission colors of R (red), Y (yellow), G (green), B (blue), and W (white) in each pixel.

  Thereafter, a 4 nm-thick Ba film was formed using a vacuum deposition method and a shadow mask as an electron injection layer so as to cover the entire display portion.

  Thereafter, ITO was patterned to a thickness of 100 nm using a metal mask by facing target sputtering (FTS) as a cathode.

  Thereafter, a protective layer SiNxCy was formed. The protective layer was formed by a plasma CVD method, and a carbon-containing silicon nitride film having a composition gradient using methane, monosilane, nitrogen gas, and hydrogen gas as source gases. Specifically, the device was transferred under nitrogen, then transferred to a plasma CVD apparatus, the vacuum chamber was depressurized to 10 ^ -2 Pa or less, silane, nitrogen, methane, hydrogen were introduced as source gases, and high frequency Plasma was generated at (13.56 MHz). As the deposition time changed, the flow rate of methane gas was reduced and the composition was inclined. Once the flow rate of methane gas was reduced to zero, the initial amount was introduced again to form a layer structure. The film thickness was 300 nm per layer, and this was repeated three times, so that the thickness of the protective layer was 900 nm.

  Then, the sealing glass substrate which apply | coated the thermosetting resin to the whole surface by the die-coater as a sealing body on the said protective film was bonded together with the element substrate using the hot roll laminator, applying the temperature of 100 degreeC. After pasting, it was further cured at 100 ° C. for 1 hour.

  The organic EL display panel thus obtained had good light emission characteristics and was driven normally.

  In addition, as a result of measuring each point in the display area at the time of non-light emission using a microscopic transmittance measuring apparatus manufactured by Otsuka Electronics Co., Ltd., the visible light transmittance in the pixel area is 75%, and the boundary between the partition wall and the anode is blurred and conspicuous It was good.

[Example 2]
In Example 2, an acrylic positive photosensitive material serving as a partition wall was formed on the entire display region with a film thickness of 1 μm, and the exposure conditions were a gap of 100 μm with a photomask and an exposure amount of 400 mJ. Thereafter, it was immersed in a developer for 20 s to remove the exposed portion, and then post-baked.
The height of the formed partition wall was 1 μm, the angle Θ1 between the pixel region a and the end of the partition wall was 30 °, and the angle Θ2 of the partition wall surface with respect to the plane parallel to the pixel region a was always Θ2 <Θ1.
Other conditions are the same as in the first embodiment. The obtained organic EL display panel had good light emission characteristics and was driven normally.

  Further, as a result of measuring the transmittance at the time of non-light emission by the same method as in Example 1, the visible light transmittance in the pixel region was 75%, and the boundary between the partition wall and the anode surface was blurred and was not outstanding.

[Example 3]
In Example 3, an acrylic positive photosensitive material serving as a partition wall was formed on the entire display region with a film thickness of 1 μm, and the exposure conditions were a gap of 150 μm with a photomask and an exposure amount of 400 mJ. Thereafter, the film was immersed in a developing solution for 40 s to remove the exposed portion, and then post-baked.
The height of the partition formed was 1 μm, the angle Θ1 between the pixel region a and the end of the partition was 20 °, and the angle Θ2 of the partition surface with respect to the plane parallel to the pixel region a was always Θ2 <Θ1.
Met.
Other conditions are the same as in the first embodiment. The obtained organic EL display panel had good light emission characteristics and was driven normally.
Further, as a result of measuring the transmittance at the time of non-light emission by the same method as in Example 1, the visible light transmittance in the pixel region was 70%, and the boundary between the partition wall and the anode surface was blurred and was not outstanding.

[Example 4]
In Example 4, an acrylic positive photosensitive material serving as a partition wall was formed on the entire display region with a film thickness of 0.5 μm, and the exposure conditions were a gap of 100 μm with a photomask and an exposure amount of 100 mJ. Thereafter, it was immersed in a developer for 20 s to remove the exposed portion, and then post-baked.
The height of the partition wall formed was 0.5 μm, the angle Θ1 between the pixel region a and the partition wall edge was 20 °, and the angle Θ2 of the partition wall surface with respect to the plane parallel to the pixel region a was always Θ2 <Θ1. .
Other conditions are the same as in the first embodiment. The obtained organic EL display panel had good light emission characteristics and was driven normally.
Further, as a result of measuring the transmittance at the time of non-light emission by the same method as in Example 1, the visible light transmittance in the pixel region was 80%, and the boundary between the partition wall and the anode surface was blurry and unnoticeable.

[Comparative Example 1]
In Comparative Example 1, the exposure conditions for forming the partition walls were a gap of 100 μm from the photomask and an exposure amount of 400 mJ. Thereafter, the film was immersed in a developing solution for 40 s to remove the exposed portion, and then post-baked.
The height of the formed partition wall was 1 μm, the angle Θ1 between the pixel region a and the partition wall edge was 60 °, and the angle Θ2 of the partition wall surface with respect to the plane parallel to the pixel region a was always Θ2 <Θ1.
Met.
Other conditions are the same as in the first embodiment. The obtained organic EL display panel had good light emission characteristics and was driven normally.
However, the transmittance at the time of non-light emission was measured in the same manner as in Example 1. As a result, the visible light transmittance in the pixel region was 70%, but the boundary between the partition wall and the anode surface was clearly visible, and the transparency was high. Was bad.

101: Transparent substrate 102: Transparent first electrode (anode)
103: partition wall 103A: side surface 104: substrate wiring for extracting anode 105: transparent second electrode (cathode)
106: Substrate wiring for taking out cathode 108: Protective layer 109: Sealing body 110: Organic light emitting medium layer 111: Hole injection layer
112: Interlayer 113: Organic light emitting layer 114: Electron injection layer a: Pixel area b: Display area 600: Letterpress printing device 601: Stage 602: Printed substrate 603: Ink tank 604: Ink chamber 605: Anilox roll 606: Doctor 607: Letterpress 608: Plate cylinder 609: Ink layer

Claims (3)

A transparent first electrode formed on a transparent substrate;
A partition wall that partitions the pixel region a by being formed on the upper surface of the transparent first electrode opposite to the transparent substrate;
A light emitting medium layer formed on the upper surface of the transparent first electrode corresponding to the pixel region a and including at least an organic light emitting layer;
A transparent second electrode formed on the upper surface of the light emitting medium layer opposite to the transparent first electrode;
A transparent organic electroluminescence display panel comprising:
The partition has a side surface located on the pixel region side,
An angle Θ1 formed by an end of the side surface that contacts the upper surface of the transparent first electrode and the upper surface of the transparent first electrode is 2 ° or more and 45 ° or less, and is separated from the upper surface of the transparent first electrode. The transparent organic electroluminescence display panel, wherein an angle Θ2 formed by the side surface with respect to a plane parallel to the top surface of the transparent first electrode is always Θ2 <Θ1.   The transparent organic electroluminescence display panel according to claim 1, wherein a height h of the partition wall is 0.2 μm or more and 2 μm or less.   The transparent organic electroluminescence display panel according to claim 1, wherein the visible light transmittance of the display region b of the transparent organic EL display is 60% or more.

Images