JP2007188743A - Organic el display panel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of dark spots by surely inhibiting moisture and oxygen from intruding into an organic EL layer. <P>SOLUTION: An organic EL display panel has: a transparent substrate 1; a plurality of color modulators 2R, G, and B regularly provided on the transparent substrate; a planarization layer 3 which is provided on a plurality of the color modulators so as to cover a plurality of the color modulators and includes a first inorganic oxide or a first inorganic nitride; a covering layer 4 which is provided on the planarization layer and includes a second inorganic oxide or a second inorganic nitride, a first electrode 5 provided on the covering layer; an organic light-emitting layer 6 provided on the first electrode; and a second electrode 7 provided on the organic light-emitting layer so as to face the first electrode. The manufacturing method of the organic EL display panel is provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic EL display panel and a manufacturing method thereof.

  Organic EL display panel production methods include “three-color light emission method” in which organic EL elements that emit red, blue, and green light when applied to an electric field, and white light emitted by organic EL elements using color filters. "Color filter system" that expresses red, blue, and green, and absorbs near-ultraviolet light, blue light, blue-green light, or white light emitted by organic EL elements, and converts the wavelength distribution to visible light A “color conversion method” using a color conversion layer including a color conversion pigment that emits light in the region has been proposed.

  Among these methods, a color mask layer and / or a color conversion layer having a desired shape and arrangement can be formed by using a photo process without using a metal mask during film formation. The “filter method” and “color conversion method” are considered to be advantageous for increasing the screen size and resolution.

  An important practical issue as a color display is that it has a fine color display function and has long-term stability including color reproducibility. However, the color organic EL display has a drawback that the light emission characteristics (current-luminance characteristics) are lowered by driving for a certain period.

  A typical cause of the deterioration of the light emission characteristics is the growth of dark spots. A dark spot is a light emitting defect point. When oxidation proceeds during driving and during storage, the growth of dark spots proceeds and spreads over the entire light emitting surface. This dark spot is considered to be caused by oxidation or aggregation of the laminated material constituting the element due to oxygen or moisture in the element. The growth proceeds not only during energization but also during storage. In particular, the growth is accelerated by (1) oxygen or moisture present around the element, and (2) oxygen or moisture present as an adsorbate in the organic laminated film. And (3) it is considered that it is also affected by moisture adsorbed on components at the time of device fabrication or moisture intrusion at the time of production.

  As a technique for preventing the moisture from entering the organic EL element, it has been proposed to provide an insulating moisture / oxygen barrier layer on the substrate. As a moisture / oxygen barrier layer, a technique of disposing an organic resin such as a polyimide-modified silicone resin (see, for example, Patent Documents 1 to 3), and an inorganic oxide layer having a thickness of 0.01 to 200 μm (Patent Documents 4 and 5) A technique for disposing a reference) is known. The inorganic oxide layer is required to have high moisture resistance in order to maintain the life of the organic light emitting layer.

  Further, there is a method of forming SiOx and SiNx by DC sputtering on the polymer film layer formed on the color filter layer, and the effect of improving the adhesion of the transparent conductive film is known (see Patent Documents 6 and 7). ). There is also a method of sintering low melting glass (see Patent Document 8).

  With regard to the performance degradation of organic EL elements, active research has been conducted in various places, and various causes have been announced so far. In particular, since the organic EL layer including the light emitting layer is made of a material having low resistance to oxygen and moisture, performance degradation due to moisture and oxygen released when the device is driven is a serious problem.

Japanese Patent Laid-Open No. 5-134112 JP-A-7-218717 JP-A-7-306311 JP-A-8-279394 JP-A-10-241860 Japanese Patent Laid-Open No. 7-146480 Japanese Patent Laid-Open No. 10-10518 JP 2000-214318 A

  The film thickness of the color conversion layer in the “color conversion method” is about 10 μm, and it is necessary to flatten the color conversion layer by some method in order to prevent color shift and wiring disconnection (Patent Document 5). For example, as an example of the planarization method, there is a method of coating and forming a polymer film. However, in this method, moisture and organic volatile components remaining in the polymer may cause device deterioration.

Meanwhile, the moisture contained in the color conversion layer or a planarization layer used to protect the organic volatile components and oxygen, an inorganic oxide film such as SiO _x or SiN _x is formed in generally a sputtering method or the CVD method However, it is known that pinholes may be formed as film defects in the film. When pinholes are formed, moisture or oxygen may reach the organic EL layer through the pinholes and dark spots may grow, and moisture and organic volatile components contained in the color conversion layer and the planarization layer There is a need for a method of reducing oxygen and oxygen.

  As another planarization method, a method of directly forming an inorganic oxide on the color conversion layer can be considered. In general, when formed by a vapor phase growth method such as sputtering or CVD, there is a problem that it is easy to peel off due to the generated stress and a problem that the film cannot be flattened because an isotropic film is deposited around the color conversion layer. Have.

  Furthermore, when molten glass is used as the inorganic oxide, the heat resistance temperature of the color conversion material is less than 200 ° C., and thus there is a problem that the molten glass having a temperature of about 400 ° C. cannot be sufficiently baked (Patent Document 8). is doing.

  Therefore, there is a strong demand for a structure that can reliably prevent moisture and oxygen from entering the organic EL layer and prevent the occurrence of dark spots.

According to one aspect of the present invention,
A transparent substrate;
A plurality of color modulation units regularly provided on the transparent substrate;
A planarization layer containing a first inorganic oxide or an inorganic nitride provided on the plurality of color modulation portions so as to cover the plurality of color modulation portions;
A coating layer containing a second inorganic oxide or inorganic nitride provided on the planarizing layer;
A first electrode provided on the covering layer;
An organic light emitting layer provided on the first electrode;
There is provided an organic EL display panel having a second electrode provided on the organic light emitting layer so as to face the first electrode.

According to another aspect of the present invention, a method of manufacturing an organic EL display panel,
Providing a transparent substrate;
Providing a plurality of color modulation units regularly on the transparent substrate;
Providing a planarizing layer containing a first inorganic oxide or an inorganic nitride on the plurality of color modulation units so as to cover the plurality of color modulation units;
Providing a coating layer containing a second inorganic oxide or inorganic nitride on the planarizing layer;
Providing a first electrode on the covering layer;
Providing an organic light emitting layer on the first electrode;
Providing a second electrode on the organic light emitting layer so as to face the first electrode.

  As will be described in detail below, according to the present invention, in all regions of the substrate, an inorganic oxide or inorganic nitride layer having excellent moisture and oxygen barrier properties is formed, and the organic EL layer is formed from the substrate side. It is possible to effectively prevent moisture and oxygen from entering. Therefore, according to the present invention, it is possible to provide an organic EL display panel that maintains excellent light emission characteristics over a long period of time without generating dark spots.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below.

  As a result of various studies, the present inventor has found that reducing the volume of the polymer layer used around the color conversion layer is an important means for suppressing dark spots. However, there has been a problem in a film forming method and a flattening method for flattening a color conversion layer having low heat resistance and a thickness of about 10 μm. Based on this knowledge, the present invention provides a structure of an organic EL element that can more effectively prevent the occurrence of dark spots.

  FIG. 1 is a cross-sectional view of an organic EL display panel according to one embodiment of the present invention. As described above, according to one aspect of the present invention, the transparent substrate 1, the plurality of color modulation units 2R, G, B, the planarization layer 3, the coating layer 4, the first electrode 5, and the organic An organic EL display panel having a light emitting layer 6 and a second electrode 7 is provided. Moreover, according to the other aspect of this invention, the manufacturing method of an organic electroluminescent display panel is provided.

  The organic EL display panel according to the present invention has a transparent substrate 1. The transparent substrate is preferably transparent to visible light (wavelength 400 to 700 nm). The transparent substrate is preferably one that can withstand the conditions (solvent, temperature, etc.) used to form the layer to be laminated. The transparent substrate is preferably excellent in dimensional stability. Preferred transparent substrates include glass substrates and rigid resin substrates formed of resins such as polyolefins, acrylic resins (including polymethyl methacrylate), polyester resins (including polyethylene terephthalate), polycarbonate resins, or polyimide resins. . Alternatively, a preferred transparent substrate includes a flexible film formed from polyolefin, acrylic resin (including polymethyl methacrylate), polyester resin (including polyethylene terephthalate), polycarbonate resin, polyimide resin, or the like. The thickness of the transparent substrate can be set to 1.1 mm, for example.

  The organic EL display panel according to the present invention has a plurality of color modulation portions 2R, 2G, and 2B regularly provided on the transparent substrate. In the present specification, “provided on” intends to be provided in the direction in which the organic light emitting layer exists with respect to the transparent substrate. The provision of the color modulation unit on the transparent substrate includes not only the case where the color modulation unit is provided directly on the transparent substrate but also the case where the color modulation unit is provided on the transparent substrate via some member. The same applies to other members. “Regularly provided” means, for example, a state in which a plurality of color modulation units are arranged at regular intervals in a matrix.

  The color modulation part can be composed of a color filter layer, a color conversion layer, or a laminate of a color filter layer and a color conversion layer. The color filter layer is a layer that transmits only light in a desired wavelength range. Further, when adopting a laminated structure of the color filter layer and the color conversion layer, the color filter layer is effective in improving the color purity of the light subjected to wavelength distribution conversion in the color conversion layer. The color filter layer can be formed using, for example, a commercially available color filter material for liquid crystal (such as a color mosaic manufactured by Fuji Film Electromaterials).

  The color conversion layer is preferably a layer having a color conversion dye and a matrix resin. The color conversion dye is a dye that converts the wavelength distribution of incident light and emits light in different wavelength ranges, and preferably has a wavelength of light from an organic light emitting layer (for example, near ultraviolet light or blue to blue-green light). A pigment that performs distribution conversion and emits light in a desired wavelength band (for example, blue, green, or red). Color conversion dyes are known in the art, such as rhodamine dyes and cyanine dyes that emit red light; coumarin dyes and naphthalimide dyes that emit green light; and coumarin dyes that emit blue light. Any thing that can be used.

  A plurality of types of color modulation units, for example, a red modulation unit that absorbs light from an organic light emitting layer and emits red light, a green modulation unit that emits green light, and a blue modulation unit that emits blue light on one transparent substrate Etc. may be provided. In the present invention, full color display is possible by arranging a plurality of types of color modulation sections in a matrix.

  The thickness of the color modulation part can be set to 10 μm, for example. In addition, the size of the color modulation unit can be set, for example, to a width of 0.08 mm and a pitch of 0.11 mm.

  The color modulation part can be formed by applying the material of each color modulation part using a spin coating method, a roll coating method, a casting method, a dip coating method, or the like, and patterning using a photolithographic method or the like.

  The organic EL display panel according to the present invention preferably further includes a light shielding portion 8 provided on the transparent substrate and between the plurality of color modulation portions. The light shielding portion can be formed using a commercially available color filter material for liquid crystal (such as a color mosaic manufactured by Fuji Film Electro Materials). The thickness of the light shielding part can be set to 1 μm, for example. The light shielding portion can be formed by applying a material for the light shielding portion using a spin coating method or the like and patterning using a photolithographic method or the like.

  The organic EL display panel according to the present invention includes a planarization layer containing a first inorganic oxide or an inorganic nitride provided on the plurality of color modulation units so as to cover the plurality of color modulation units. 3 and a coating layer 4 containing a second inorganic oxide or inorganic nitride provided on the planarizing layer. The planarization layer containing the first inorganic oxide or inorganic nitride and the coating layer containing the second inorganic oxide or inorganic nitride each function as a moisture-proof layer.

  The flattening layer is provided so as to cover a plurality of color modulation portions, particularly for the purpose of flattening the unevenness of the color modulation portions. The phrase “provided so as to cover” intends that an integrated planarization layer is provided so as to spread over a plurality of color modulation portions. That is, the planarization layer is provided not only in the region above the color modulation unit but also in the region between the plurality of color modulation units. As will be described later, when the organic resin portion is provided between the plurality of color modulation portions, the planarization layer is preferably provided on the organic resin portion between the plurality of color modulation portions. Further, the surface of the planarizing layer on the coating layer side is flat. That is, the planarization layer has the same surface height on the coating layer side in the region above the color modulation portion and the region between the plurality of color modulation portions. Note that the unevenness on the surface of the planarization layer is preferably 1 μm or less, and more preferably 0.5 μm or less. The unevenness of the surface of the planarization layer can be measured by performing an evaluation by measuring a filtered waviness curve using, for example, Surfcom 1800D (manufactured by Tokyo Seimitsu Co., Ltd.).

The planarizing layer and the covering layer are made of insulating inorganic oxides such as SiO _x , SiN _x , SiN _x O _y , AlO _x , TiO _x , TaO _x , ZnO _x , inorganic nitride, inorganic oxynitride (inorganic oxidation Or the like contained in the inorganic nitride). In particular, the planarizing layer and the covering layer are preferably formed using SiO _x and SiN _x O _y having a small difference in refractive index from the material of the color modulation portion. Further, the first inorganic oxide or inorganic nitride is preferably silicon oxide. This is because it can be suitably formed using tetraethoxysilane or the like, as will be described later. The second inorganic oxide or inorganic nitride is preferably silicon oxide or silicon oxynitride. This is because it can be suitably formed using monosilane or the like, as will be described later. The first inorganic oxide or inorganic nitride and the second inorganic oxide or inorganic nitride may be the same material or different materials. Moreover, as will be described in detail below, the planarization layer preferably further contains carbon. More specifically, in the planarization layer, the carbon content is preferably 0.5 to 20 at%, and more preferably 2 to 10 at%. Moreover, it is preferable that the said coating layer does not contain carbon substantially. More specifically, in the coating layer, the carbon content is preferably 1 at% or less, and more preferably 0.5 at% or less.

  As described above, moisture and volatile components contained in the color conversion layer and the organic flattening layer have been one of the causes of dark spots. In the present invention, planarization and passivation are performed using an inorganic oxide layer or the like without using an organic planarization layer. For this reason, according to the present invention, the occurrence of dark spots can be eliminated from the cause, and the occurrence of dark spots can be effectively prevented.

  The thickness of the planarizing layer is preferably 0.1 to 5 μm, and preferably 0.3 to 1 μm in the region above the color modulation portion (not the region between the plurality of color modulation portions). Further preferred. Moreover, it is preferable that the thickness of a coating layer is 0.2-5 micrometers, and it is still more preferable that it is 0.3-1 micrometer. In addition, the total thickness of the planarizing layer and the coating layer is preferably 0.2 to 10 μm, and more preferably 0.6 to 3 μm, in the region above the color modulation portion. By setting the film thicknesses of the planarization layer and the coating layer in the above range, it is possible to suitably prevent the light emitted from the light emitting layer from propagating in the lateral direction, the adjacent pixels emit light, display unevenness, etc. It is possible to suitably prevent the occurrence of light emission failure.

  In FIG. 2, the schematic diagram of the formation process of the planarization layer and coating layer in the organic electroluminescent display panel concerning this invention is shown. As shown in FIG. 2, the method for manufacturing an organic EL display panel according to the present invention includes a first inorganic oxide or inorganic so as to cover the plurality of color modulation units on the plurality of color modulation units. Providing a planarization layer 3 containing nitride. Providing the planarizing layer comprises: (a) providing a first inorganic oxide or inorganic nitride layer 3 ′; and (b) polishing the first inorganic oxide or inorganic nitride layer. And planarizing the surface thereof. Moreover, the manufacturing method of the organic electroluminescent display panel concerning this invention includes the step which provides the coating layer 4 containing a 2nd inorganic oxide or inorganic nitride on the said planarization layer (c).

  As described above, it is preferable that the step of providing the planarization layer includes the step of (a) providing the first inorganic oxide or inorganic nitride layer. Moreover, it is preferable that the said step is performed using an alkoxysilane as a raw material. The alkoxysilane is preferably at least one selected from the group consisting of tetraethoxysilane, tetramethoxysilane, tetraporopoxysilane, methyltrimethoxysilane, and methyltriethoxysilane. The step is preferably performed using a CVD method, and more preferably performed using a plasma CVD method. Thereby, a planarization layer containing silicon oxide or silicon nitride is formed.

  The film forming conditions are preferably as follows. The film formation is preferably performed at a temperature of less than 150 ° C, and more preferably performed at a temperature of 50 to 130 ° C. This is for preventing the deactivation of the dye of the color modulation layer. When alkoxysilane is used as the film forming gas, film formation is generally performed at a substrate temperature of 200 ° C. or higher. However, in the present invention, the substrate temperature is set to positively leave carbon in the film. Film formation is performed in a state lower than usual.

In the present invention, any of a parallel plate method, an ECR method, an ICP method, a helicon wave plasma method, and the like can be used as the plasma CVD device, and the parallel plate method is preferable from the viewpoint of device cost. In the case of using a parallel plate type plasma CVD apparatus, it is preferable that the film forming pressure is in the range of 100 to 800 Pascal, and the film forming power is in the range of 0.8 W / cm ^{2 to 3} W / cm ² . The slower the film formation rate is, the more dense the film is, so that the effect as a passivation layer is improved. On the other hand, the productivity is lowered, so the film formation rate is 100 nm / min to 1000 nm / min. Minutes are preferred.

  When tetraethoxysilane or the like is used as a raw material, sufficient decomposition is not performed in plasma, so that a planarization layer containing carbon and hydrogen is formed. In general, when a layer of inorganic oxide or the like contains impurities such as carbon, a dense film is difficult to form, and moisture resistance tends to be low. On the other hand, when an impurity such as carbon is contained, a film having a small residual stress and not easily peeled off is formed. That is, generally, the inorganic oxide layer is easily peeled off due to residual stress, and it is difficult to form a 10 μm thick layer. However, according to the present invention, since a layer made of an inorganic oxide or the like is formed so as to contain impurities such as carbon, it is possible to form a film that has a small residual stress and is difficult to peel off. In addition, in order to ensure moisture resistance, the coating layer mentioned later is further provided.

  Furthermore, since the deposition rate can be increased by forming a film at a low temperature using tetraethoxysilane or the like as a raw material, irregularities in the color modulation portion can be produced. When film formation is performed at a low temperature using tetraethoxysilane or the like, since the source gas is not sufficiently decomposed, carbon contained in the source gas remains in the deposited film. As a result, the film formation rate is faster than when the film is formed at a high temperature.

  Preferably, the step of providing a planarization layer includes (b) polishing the first inorganic oxide or inorganic nitride layer and planarizing the surface thereof. In the vapor phase film formation such as the CVD method, the film is deposited almost isotropically. Therefore, the obtained film does not have a flat surface as it is. For this reason, it is preferable to flatten the surface by polishing to form a flattened layer. Polishing can be performed by a CMP method, a tape polishing method, or the like. From the viewpoint of reducing particles adhering to the surface of the planarization layer, it is preferable to use a CMP method established in a semiconductor process. When the CMP method is used, a CMP pad and a CMP slurry are selected as appropriate.

  The method for manufacturing an organic EL display panel according to the present invention includes a step of providing a coating layer containing a second inorganic oxide or inorganic nitride on the planarizing layer. The coating layer is provided particularly for the purpose of reducing defects such as pinholes and obtaining a highly moisture-proof film quality. The coating layer can be formed by a sputtering method, a CVD method, or the like.

When the coating layer is provided by a CVD method (preferably a plasma CVD method), it is preferable that the step of providing the coating layer is performed using silicon hydride as a raw material. Note that in this specification, silicon hydride does not contain an organosilane compound. Specifically, the silicon hydride is preferably at least one selected from the group consisting of monosilane, dichlorosilane, and trichlorosilane. In the plasma CVD method, it is preferable to perform film formation by introducing O ₂ , N _2, or NO _x gas into the gas such as monosilane. It is also possible to apply a bias to the substrate side in combination with an RF power source for generating plasma.

When the coating layer is provided by sputtering, it is preferable to use a Si target. Further, it is preferable to use Ar and O ₂ gas or N ₂ gas as the sputtering gas. Further, it is preferable to form a film by an RF method or a dual cathode method. Deposition pressure is 0.2 to 2 Pascal, deposition power is preferably in the range of ^{0.5W / cm 2 ~3W / cm 2} .

  The number of dark spots generated is correlated with the result of a pinhole test (a film is deposited on a silicon wafer and immersed in a KOH aqueous solution to count silicon etch pits). For this reason, the pinhole test can be set as one of indexes for selecting a film forming method and a film type. In general, the occurrence of pinholes (or film defects) can be reduced by examining film formation conditions such as suppression of dust generation during film formation (preparation and removal) and suppression of abnormal discharge. Furthermore, surprisingly, rather than depositing a layer of inorganic oxide or the like continuously on the polymer film, the inorganic oxide is intermittently formed (separating the film thickness or changing the film type). It has been found by the present inventors that the number of pinholes and defects is smaller when the same layer is deposited. Also in this respect, the present invention in which the planarizing layer and the coating layer are separately provided can more effectively prevent the generation of pinholes and consequently dark spots.

  The organic EL display panel according to the present invention preferably further includes an organic resin portion 9 provided on the transparent substrate (preferably on the light shielding portion) and provided between the plurality of color modulation portions. By providing the organic resin portion, the adhesion between the color modulation portion and the planarization layer can be further enhanced. That is, the organic resin portion is preferably provided at the interface between the color modulation portion and the planarization layer and at the interface between the transparent substrate (or the light shielding portion) and the planarization layer, excluding the region above the color modulation portion. The material of the organic resin part is preferably a material having high transparency in the visible region (transmittance of 50% or more in the range of 400 to 700 nm), Tg of 100 ° C. or more, and surface hardness of 2H or more in pencil hardness. As a material of the organic resin part, for example, an imide-modified silicone resin, an epoxy-modified acrylate resin as an ultraviolet curable resin, a resin having a reactive vinyl group of acrylate monomer / oligomer / polymer, a photo-curable type such as a resist resin Examples thereof include a resin and / or a thermosetting resin.

  The thickness of the organic resin portion is preferably 0.5 to 5 μm, more preferably 1 to 3 μm in the region between the plurality of color modulation portions (respectively, the thickness at the center portion thereof). Show). Further, the thickness of the organic resin portion is preferably 0.1 to 3 μm, more preferably 0.5 to 2 μm in the region above the color modulation portion (respectively, the thickness at the center portion thereof). Show). The thickness of the organic resin portion may be a thickness that can ensure the adhesion between the planarizing layer and the color modulation portion, and it is desirable to form the organic resin portion as thin as possible for the purpose of reducing the content of the gas released such as moisture.

  In FIG. 3, the schematic diagram of the formation process of the organic resin part in the organic electroluminescent display panel concerning this invention, a planarization layer, and a coating layer is shown. As shown in FIG. 3, the organic resin portion can be formed as follows. The organic resin portion can be formed by applying the material of each layer using a spin coat method, a roll coat method, a cast method, a dip coat method, etc., and then patterning using a photolithographic method or the like. For example, when the organic resin portion is formed by spin coating, the organic resin portion tends to be formed along the side surface of the color modulation layer as shown in FIG. This is considered to be due to the property that the color modulation layer is covered by the wettability of the organic resin material to the color modulation layer, but the film thickness is suppressed by the centrifugal force during spin coating between the color modulation layers.

The organic EL display panel according to the present invention has a first electrode 5 provided on the coating layer. The organic EL panel preferably has a plurality of striped first electrodes extending in the first direction. The first electrode is preferably a transparent electrode, and specifically has a transmittance of preferably 50% or more, more preferably 85% or more with respect to light having a wavelength of 400 to 800 nm. As the material of the first electrode, a conductive metal oxide such as SnO ₂ , In ₂ O ₃ , ITO, IZO, an alloy of ZnO and Al can be used. The first electrode can be formed by a known method such as sputtering. The thickness of the first electrode is usually 50 nm or more, preferably 50 nm to 1 μm, more preferably 100 to 500 nm.

  The organic EL panel according to the present invention preferably further includes an auxiliary electrode. The resistance of the first electrode can be suppressed by the auxiliary electrode. Examples of the material of the auxiliary electrode include metals such as Al, Mo, Ni, Cr, and W. The auxiliary electrode can be provided in any of the display region and the region for forming the lead line with the external drive circuit of the first electrode. For example, in the display area, it is arranged along the edge of the first electrode so as to be in contact with the first electrode in parallel with the first electrode so as not to prevent light emission from the organic light emitting layer. Can do. Further, the lead line forming region can be formed with the same width as the first electrode for the purpose of reducing the electric resistance of the first electrode. The thickness of the auxiliary electrode is usually 50 nm or more, preferably 50 nm to 1 μm.

The organic EL display panel according to the present invention has an organic light emitting layer 6 provided on the first electrode. The organic EL panel can further have a hole injection layer, a hole transport layer, an electron transport layer, and / or an electron injection layer as necessary. Specifically, the organic light emitting device can have the above layers in the order shown below, for example. In the organic EL panel having the following laminated structure (1) to (7), the anode is electrically contacted with the organic light emitting layer or the hole injection layer, and the organic light emitting layer, electron transport layer or electron The cathode is in electrical contact with the injection layer.
(1) Organic light emitting layer (2) Hole injection layer / organic light emitting layer (3) Organic light emitting layer / electron injection layer (4) Hole injection layer / organic light emitting layer / electron injection layer (5) Hole transport layer / Organic light emitting layer / electron injection layer (6) Hole injection layer / hole transport layer / organic light emitting layer / electron injection layer (7) Hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer

Any known material can be used as the material of the organic light emitting layer. For example, in order to obtain light emission from blue to blue-green, for example, a condensed aromatic ring compound, a ring assembly compound, a metal complex (such as an aluminum complex such as Alq ₃ ), a styrylbenzene compound (4,4′-bis (diphenyl) (Vinyl) biphenyl (DPVBi) and the like), porphyrin compounds, benzothiazole compounds, benzimidazole compounds, benzoxazole compounds and the like, and materials such as aromatic dimethylidin compounds are preferably used. Or you may form the organic light emitting layer which emits the light of a various wavelength range by adding a dopant to a host compound. Examples of host compounds include distyrylarylene compounds (for example, IDE-120 manufactured by Idemitsu Kosan Co., Ltd.), N, N′-ditolyl-N, N′-diphenylbiphenylamine (TPD), aluminum tris (8-quinolinolate) (Alq ₃ ). ) Etc. can be used. As dopants, perylene (blue purple), coumarin 6 (blue), quinacridone compounds (blue green to green), rubrene (yellow), 4-dicyanomethylene-2- (p-dimethylaminostyryl) -6-methyl- 4H-pyran (DCM, red), platinum octaethylporphyrin complex (PtOEP, red), or the like can be used.

  As the forest material for the hole injection layer, Pc (including CuPc) or indanthrene compounds can be used. The hole transport layer can be formed using a material having a triarylamine partial structure, a carbazole partial structure, or an oxadiazole partial structure. Materials that can be used preferably include TPD, [alpha] -NPD, MTDAPB (o-, m-, p-), m-MTDATA, and the like.

The material of the electron transport layer, aluminum complexes such as A1q _3; PBD, oxadiazole derivatives such as TPOB; thiophene derivatives such as BMB-2T; triazine derivatives; phenylquinoxalines such triazole derivatives such as TAZ Can be used. As the material for the electron injection layer, an aluminum complex such as Alq ₃ or an aluminum quinolinol complex doped with an alkali metal or an alkaline earth metal can be used.

  Optionally, an electron injecting material such as an alkali metal, an alkaline earth metal, an alloy containing them, or an alkali metal fluoride is provided at the interface between the organic light emitting layer (or electron transport layer or electron injection layer) and the cathode. By providing a buffer layer of a thin film (for example, a film thickness of 10 nm or less), the electron injection efficiency can be increased.

  The thicknesses of the hole injection layer, the hole transport layer, the organic light emitting layer, the electron transport layer, and the electron injection layer should be appropriately set so as to be sufficient for realizing the desired characteristics in each. For example, it can be set to 100 nm, 20 nm, 30 nm, 20 nm, and 10 nm, respectively. In addition, the hole injection layer, the hole transport layer, the organic light emitting layer, the electron transport layer, and the electron injection layer are formed by using any means known in the art such as vapor deposition (resistance heating or electron beam heating). can do.

  The organic EL display panel according to the present invention has a second electrode 7 provided on the organic light emitting layer so as to face the first electrode. The organic EL panel preferably has a plurality of striped second electrodes extending in a second direction that intersects (preferably orthogonally) the first direction of the first electrode. In this manner, passive matrix driving can be performed by providing the first electrode and the second electrode that intersect in a matrix.

  The second electrode is preferably a reflective electrode, and is preferably formed using a highly reflective metal, amorphous alloy, or microcrystalline alloy. High reflectivity metals include Al, Ag, Mo, W, Ni, Cr, and the like. High reflectivity amorphous alloys include NiP, NiB, CrP, CrB, and the like. The highly reflective microcrystalline alloy includes NiAl and the like. The second electrode may be used as a cathode or an anode. When the second electrode is used as a cathode, the aforementioned buffer layer may be provided at the interface between the second electrode and the organic light emitting layer to improve the efficiency of electron injection into the organic light emitting layer.

  The second electrode can be formed using any means known in the art such as vapor deposition (resistance heating or electron beam heating), sputtering, ion plating, laser ablation, etc., depending on the material used. it can. A plurality of second electrodes may be formed using a mask that gives a desired shape, or a plurality of second electrodes may be formed using a separation partition wall having a reverse tapered cross-sectional shape. .

  The second electrode may have a stripe shape extending in the second direction. Here, the first direction relating to the first electrode and the second direction are preferably crossed, more preferably orthogonal. By adopting such a configuration, by applying an electric field to one of the first electrodes and one of the second electrodes, passive matrix driving for emitting light from the organic light-emitting layer at the intersection of the electrodes is performed. It can be carried out.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. However, the present invention is not limited to the examples described below.

[Example 1]
As an organic EL display panel according to Example 1, an organic EL display panel having 160 × 120 pixels (RGB) and a pixel pitch of 0.33 mm was produced.

  Fusion glass (Corning 1737 glass, 100 × 100 × 1.1 mm) was used as the transparent substrate 1.

  On the transparent substrate, the black matrix 8 was formed as follows. A black matrix material (manufactured by Fuji Film Electronics Materials Co., Ltd .: Color Mosaic CK-7800) was applied on a transparent substrate using a spin coating method, and patterning was performed by a photolithography method. As a result, a black matrix having openings with a width of 0.03 mm, a pitch of 0.11 mm, and a film thickness of 1 μm was obtained.

  Then, the blue conversion filter layer 2B was formed on the transparent substrate as follows. A blue filter material (Fuji Film Electronics Materials Co., Ltd .: Color Mosaic CB-7001) was applied on a transparent substrate using a spin coating method, and patterning was performed by a photolithography method. As a result, a blue color conversion filter layer composed of a plurality of stripes having a width of 0.08 mm, a pitch of 0.33 mm, and a thickness of 10 μm was obtained.

  Thereafter, a green color conversion filter layer 2G was formed on the transparent substrate as follows. Coumarin 6 (0.7 parts by weight) as a fluorescent dye was dissolved in 120 parts by weight of a solvent, propylene glycol monoethyl acetate (PGMEA). 100 parts by weight of V259PA / P5 manufactured by Nippon Steel Chemical Co., Ltd. was added to the obtained solution and dissolved to obtain a coating solution. This coating solution was applied onto a transparent substrate and patterned by a photolithography method. As a result, a green color conversion filter layer composed of a plurality of stripes having a width of 0.08 mm, a pitch of 0.33 mm, and a thickness of 10 μm was obtained. The green color conversion filter layer is composed of only the color conversion layer.

  Thereafter, a red color conversion filter layer 2R was formed on the transparent substrate as follows. Coumarin 6 (0.6 parts by weight), rhodamine 6G (03 parts by weight) and basic violet (0.3 parts by weight) were dissolved in 120 parts by weight of PGMEA as fluorescent dyes. 100 parts by weight of B259PA / P5 manufactured by Nippon Steel Chemical Co., Ltd. was added to and dissolved in the obtained solution to obtain a coating solution. This coating solution was applied onto a transparent substrate and patterned for photolithography. As a result, a red conversion filter layer composed of a plurality of stripes having a width of 0.08 mm, a pitch of 0.33 mm, and a thickness of 10 μm was obtained. Note that the red color conversion filter layer is composed of only the color conversion layer.

Thereafter, the planarizing layer 3 was formed on the black matrix and the color conversion filter layer of each color as follows. First, an SiO ₂ film, which is a first inorganic oxide layer, was formed on the black matrix and the color conversion filter layer of each color. The film formation was performed using a parallel plate type plasma CVD apparatus. In the film formation process, the atmosphere was set to 5 sccm of TEOS gas (1 atm, 0 ° C., the same applies hereinafter) and 200 sccm of O ₂ gas. The RF applied power was 200 W, and the substrate stage temperature was 100 ° C. The film thickness was about 12 μm on the black matrix.

  Thereafter, the planarization layer 3 was formed by polishing the first inorganic oxide layer. Polishing was performed by a CMP method. A commercially available 8-inch rotary type was used as the CMP apparatus. A foamed polyurethane pad was used as the CMP pad. An abrasive-free Cu slurry was used as the CMP slurry. In the polishing process, the applied pressure was 5 kPa. The thickness of the planarized layer after polishing was about 1 μm on the color conversion layer. The unevenness on the surface of the planarizing layer was within 0.5 μm.

Thereafter, a SiO ₂ film, which is a second inorganic oxide layer, was formed as a coating layer 4 on the planarizing layer as follows. Film formation was performed by a sputtering method. In the film forming process, a boron-doped Si target was used as the sputtering target. A boron-doped Si target having a conductivity of about 1 Ωcm was used. As a result, the effect of suppressing charging on the target surface and reducing the frequency of occurrence of abnormal discharge was obtained. Ar and O ₂ mixed gas was used as the sputtering gas. The film thickness was 300 nm.

Then, the 1st electrode 5 and the organic light emitting layer protection part (dummy pattern) were formed on the coating layer as follows. Using a DC sputtering method (target In—Zn oxide, sputtering gas: O ₂ and Ar), 200 nm of IZO was deposited on the entire surface of the coating layer 8 at room temperature. Thereafter, patterning was performed by a photolithography method using an oxalic acid aqueous solution as an etching solution. The first electrode was positioned above the color conversion filter layer and formed in a stripe shape having a width of 01 mm and a pitch of 011 mm extending in the same direction as the stripe of the color conversion filter. The dummy pattern had a width of 0.5 mm, a length of 40.25 mm, and a thickness of 200 nm outside the display area and inside the position where the lead line from the second electrode was formed.

  Next, an insulating film (polyimide film, Photo Nice manufactured by Toray Industries, Inc.) (not shown) was formed on the gap between the stripes of the first electrode 5 and the dummy pattern by using a photolithographic method.

  Thereafter, a reflective electrode separation partition wall (not shown) was formed on the first electrode as follows. After applying a negative photoresist (ZPN 1168 made by Nippon Zeon Co., Ltd.) by spin coating, pre-baking, baking a predetermined pattern using a photomask, and performing post-exposure baking on a 110 ° C. hot plate for 60 seconds Development was performed, and heating was performed on a hot plate at 160 ° C. for 15 minutes. As a result, a stripe-shaped reflective electrode separation partition wall extending in a direction perpendicular to the stripe of the first electrode and having a reverse tapered cross section was formed in a region where the second electrode was not provided.

Thereafter, a hole injection layer (not shown), a hole transport layer (not shown), an organic light emitting layer 6 and an electron injection layer (not shown) were formed on the first electrode as follows. . A substrate having a structure below the reflective electrode separation partition was mounted in a resistance heating vapor deposition apparatus, and a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron injection layer were sequentially formed without breaking the vacuum. During film formation, the internal pressure of the vacuum chamber was reduced to 1 × 10 ⁻⁴ Pa. As the hole injection layer, copper phthalocyanine (CuPc) having a thickness of 100 nm is used, and as the hole transport layer, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (α having a thickness of 20 nm is used. 1NPD) was used as an organic light-emitting layer, and 4,4′-bis (2,2′-diphenylvinyl) biphenyl (DPVBi) with a thickness of 30 nm was laminated, and Alq3 with a thickness of 20 nm was laminated as an electron lifetime layer. .

  Next, the second electrode 7 was formed on the electron injection layer as follows without breaking the vacuum. Mg / Ag (mass ratio 10/1) was deposited by using a mask capable of obtaining a stripe pattern having a width of 300 μm and a pitch of 330 μm (gap width of 30 μm) extending in a direction perpendicular to the stripe pattern of the first electrode. As a result, a second electrode having a thickness of 200 nm was obtained.

  The organic EL display panel thus obtained was sealed with a sealing glass (not shown) and a UV curable adhesive in a glove box in a dry nitrogen atmosphere (both oxygen and moisture concentrations were 10 ppm or less).

[Example 2]
An organic EL display panel according to Example 2 was produced in the same manner as Example 1 except for the coating layer. As the coating layer, a SiN _x film as a second inorganic nitride layer was formed. The coating layer was formed using a parallel plate type plasma CVD apparatus. In the film forming process, the atmosphere was set to 50 sccm of SiH ₄ gas and 200 sccm of N ₂ gas. The RF applied power was 150 W, and the substrate stage temperature was 100 ° C. The film thickness was about 300 nm.

[Example 3]
An organic EL display panel according to Example 3 was produced in the same manner as in Example 1 except that the organic resin portion 9 was further formed as an adhesion layer after forming the color conversion layer. A planarizing material (manufactured by JSR: NN810L) was applied by using a spin coating method, and patterning was performed by a photolithography method to form an organic resin portion that covers the color conversion layer and the black matrix. The film thickness of the organic resin portion was 1 μm on the black matrix and 0.2 μm on the color conversion layer (each indicates the thickness at the center).

[Comparative Example 1]
An organic EL display panel according to Comparative Example 1 was produced in the same manner as in Example 1 except that the planarizing layer was formed of an organic resin instead of the planarizing layer containing the first inorganic oxide. After the color conversion layer was formed, a planarization layer was formed from an organic resin. A planarizing material (manufactured by JSR: NN810) was applied by using a spin coating method, and patterning was performed by a photolithography method to form a planarizing layer covering the color conversion layer and the black matrix. The thickness of the flattening layer was 5 μm on the black matrix and 2 μm on the color conversion layer (each indicates the thickness at the center). Thereafter, in the same manner as the coating layer in Example 1, an SiO ₂ film was formed as a coating layer containing an inorganic oxide.

[Evaluation]
The organic EL display panels according to Examples 1 to 3 and Comparative Example 1 were tested for the occurrence of dark spots. The test was performed by comparing the dark spot density after driving for 1000 hours at Duty 1/60, surface brightness of 100 cd / m ² , and room temperature. The dark spot density was calculated as follows. In the lighting state of the organic EL display panel, the number of areas in which the area of the non-lighting area (the part where the luminance is 50% or more lower than the surrounding area) is 10 μm ² or more is counted. This was divided by the area of the display area to calculate the dark spot density (number of dark spots per cm ² ). For each example and comparative example, the number of panels was 10 and the front of the panel was observed. Table 1 shows the dark spot density observed in the organic EL display panels according to Examples 1 to 3 and Comparative Example 1.

  As can be seen from Table 1, the organic EL display panels of Examples 1 and 2 have fewer dark spots than the organic EL display panel of Comparative Example 1. From this, it can be seen that the organic EL layer 60 can be more effectively protected from moisture and oxygen by forming the planarization layer using an inorganic oxide or an inorganic nitride instead of the organic resin. From the above, it has been found that forming a planarization layer using an inorganic oxide or an inorganic nitride is effective in preventing the occurrence of dark spots and extending the lifetime of the device.

  The organic EL display panel using the organic resin layer of Example 3 is inferior to Examples 1 and 2 in terms of the number of dark spots generated, but particularly has the effect of improving the adhesion with the planarizing layer on the black matrix material. Thus, the frequency of occurrence of peeling of the flattening layer in the polishing process of the flattening layer could be suppressed.

FIG. 1 is a cross-sectional view of an organic EL display panel according to one embodiment of the present invention. In FIG. 2, the schematic diagram of the formation process of the planarization layer and coating layer in the organic electroluminescent display panel concerning this invention is shown. In FIG. 3, the schematic diagram of the formation process of the organic resin part in the organic electroluminescent display panel concerning this invention, a planarization layer, and a coating layer is shown.

Explanation of symbols

1: transparent substrate 2R, G, B: color modulation part 3: flattening layer 4: coating layer 5: first electrode 6: organic light emitting layer 7: second electrode 8: organic resin part 9: shielding part

Claims (12)

A transparent substrate;
A plurality of color modulation units regularly provided on the transparent substrate;
A planarization layer containing a first inorganic oxide or an inorganic nitride provided on the plurality of color modulation portions so as to cover the plurality of color modulation portions;
A coating layer containing a second inorganic oxide or inorganic nitride provided on the planarizing layer;
A first electrode provided on the covering layer;
An organic light emitting layer provided on the first electrode;
An organic EL display panel comprising: a second electrode provided on the organic light emitting layer so as to face the first electrode.   The organic EL display panel according to claim 1, further comprising an organic resin portion provided on the transparent substrate and between the plurality of color modulation portions.   The organic EL display panel according to claim 1, wherein the planarizing layer further contains carbon.   The organic EL display panel according to claim 1, wherein the coating layer contains substantially no carbon. An organic EL display panel manufacturing method comprising:
Providing a transparent substrate;
Providing a plurality of color modulation units regularly on the transparent substrate;
Providing a planarizing layer containing a first inorganic oxide or an inorganic nitride on the plurality of color modulation units so as to cover the plurality of color modulation units;
Providing a coating layer containing a second inorganic oxide or inorganic nitride on the planarizing layer;
Providing a first electrode on the covering layer;
Providing an organic light emitting layer on the first electrode;
Providing a second electrode on the organic light emitting layer so as to face the first electrode. Providing the planarizing layer comprises:
Providing a first inorganic oxide or inorganic nitride layer;
Polishing the first inorganic oxide or inorganic nitride layer and planarizing the surface thereof.   The method according to claim 5, further comprising: providing an organic resin portion between the plurality of color modulation portions on the transparent substrate.   The method according to claim 5, wherein the step of providing the planarization layer is performed using alkoxysilane as a raw material.   The method according to claim 8, wherein the step of providing the planarizing layer is performed using a CVD method.   The method according to claim 5, wherein the step of providing the coating layer is performed using silicon hydride as a raw material.   The method according to claim 10, wherein the step of providing the covering layer is performed using a CVD method.   The method according to claim 5, wherein the step of providing the covering layer is performed using a sputtering method.

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