JPWO2012132292A1 - Organic EL display element, organic EL display device, and manufacturing method thereof - Google Patents

Abstract

Provided is an organic EL display element capable of making the film thickness of an organic material more uniform in a light emitting region. A substrate, a first electrode formed on the substrate, and a region of a first opening formed at least on and around the peripheral edge of the first electrode and corresponding to a light emitting region of a pixel on the first electrode And a second insulation forming a second opening so as to surround the outer periphery of the first opening on the outer peripheral side of the first insulating layer portion formed at the peripheral edge of the first electrode. A light-emitting medium layer formed on the second opening and including at least one wet coat layer and an organic light-emitting layer formed by using a wet coating method, and the light-emitting medium layer with respect to the second opening A second electrode formed opposite to the first electrode with a thickness of the first insulating layer formed on the first electrode being the first of the wet coat layers The first wet coat layer formed on the electrode side is thinner than the first wet coat layer and the first A thin film than the pole thickness.

Description

  The present invention relates to an organic EL (electroluminescence) display element, an organic EL display device, and a manufacturing method thereof.

  An organic EL display element has a structure in which an organic light emitting layer exhibiting at least an EL phenomenon is sandwiched between an electrode as an anode and an electrode as a cathode, and when a voltage is applied between the electrodes, This is a self-luminous display element in which an organic light emitting layer emits light by injecting holes and electrons into the light emitting layer and recombining the holes and electrons in the organic light emitting layer. Furthermore, in an organic EL display element, for the purpose of increasing luminous efficiency, electron transport between the anode and the organic light emitting layer, the hole injection layer, the hole transport layer, or the organic light emitting layer and the cathode is performed. Functional layers such as a layer and an electron injection layer are appropriately selected and provided. The organic light emitting layer and these functional layers such as a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer are collectively referred to as an organic light emitting medium layer.

  Organic materials that form the organic light emitting medium layer include low-molecular materials and high-molecular materials. As a method often used for forming an organic light emitting medium layer using a low molecular material as an organic material, there is a method of forming a thin film by a vacuum deposition method or the like. At this time, patterning is performed using a fine pattern mask. However, this method has a problem that patterning accuracy is less likely to increase as the substrate becomes larger. In addition, since the film is formed in a vacuum, there is a problem that the throughput is poor.

  Therefore, a method of forming a thin film by dissolving a high molecular material or a low molecular material in a solvent to obtain an ink has been tried. Examples of the wet coating method for forming a thin film include a spin coating method, a bar coating method, a slit coating method, and a dip coating method. However, in order to perform patterning with high definition or separate application to RGB three colors, these wet coating methods are difficult, and it is considered that thin film formation by a printing method that is good at coating and patterning is most effective.

  When these organic materials are dissolved or dispersed in a solvent to obtain an ink, the concentration needs to be about 1% from the solubility of the organic material. As a method for printing this ink, a relief printing method using an elastic rubber plate or a resin plate (see, for example, Patent Document 1), and an inkjet method (see, for example, Patent Document 2) have been proposed.

  When an organic light emitting medium layer is formed on a substrate to be printed by these relief printing method or ink jet method, ink having a concentration of about 1% is transferred to the substrate to be printed as it is. Therefore, when the organic light emitting ink is separately applied to RGB three colors, the organic light emitting ink spreads to adjacent pixels, resulting in color mixing. Therefore, a method is used in which partition walls are provided in order to suppress the spread of ink, and organic light emitting ink is printed in the pixel electrodes partitioned by the partition walls.

In general, an insulating material such as patterned photosensitive polyimide is formed on the partition so as to partition the subpixel. At this time, the barrier rib pattern is formed so as to cover the edge portion of the transparent electrode formed as an anode, and the barrier rib pattern defines the subpixel region.
In the film forming method using the relief printing method or the ink jet method, since the coating film is dried in the pixels surrounded by the partition walls, a phenomenon like a coffee stain occurs in the periphery of the pixel, and as a result, the pixel opening Among the portions, there is a problem that the coating thickness after drying is thin in the central portion, and there is a problem that the coating thickness in the outer peripheral portion in contact with the partition wall becomes thick, resulting in poor flatness.

  FIG. 1 shows a cross section of an example of a pixel in a conventional organic EL display element. A partition wall 03 is formed so as to cover the peripheral end portion of the first electrode 02, and an EL light emitting region 06 is defined by an edge of the partition wall 03. In this configuration, when the organic layer constituting the light emitting medium layer 04 is formed by the wet coating method, when the solution in which the organic material is dissolved is put into the opening partitioned by the partition wall 03 and dried, as shown in FIG. The film thickness becomes non-uniform due to a phenomenon such as liquid approaching. Specifically, the thickness of the light emitting medium layer 04 increases in the vicinity of the partition wall. In FIG. 1, the code | symbol 05 shows a 2nd electrode.

  In the organic EL display element, the thickness of each layer of the light emitting medium layer is important for producing an efficient and reliable display element. However, when the flatness of the coating film thickness in the pixel is deteriorated due to the influence of the partition wall 03, the portion where the film thickness is relatively thin mainly emits light, resulting in a cat-like light emission shape. Or a region where the film thicknesses of the respective layers are not the optimum combination increases. As a result, there is a problem that the pixel light emission efficiency is lowered.

  In addition, when the film thickness flatness is poor, with the progress of the electrical resistance increase of the organic layer that occurs as a aging phenomenon due to organic EL light emission, the current injection amount and The amount of luminescence increases. As a result, as a phenomenon caused by the difference in the degree of optical interference due to the difference in film thickness, there arises a problem that the wavelength component of the extracted light changes and the chromaticity changes with time. For example, when the light emission of the thick film portion is increased in blue, a problem that the high wavelength component is increased and the color is changed to light blue may occur.

JP 2001-155858 A JP 2002-305077 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic EL display element having a uniform organic material film thickness in a light emitting region and a method for manufacturing the same.

In order to solve the above problems, an organic EL display element which is one embodiment of the present invention is formed on a substrate, a first electrode formed on the substrate, and at least on and around the peripheral edge of the first electrode. A first insulating layer that divides a region of a first opening corresponding to a light emitting region of a pixel on the first electrode, and a peripheral end of the first electrode and a first insulating layer portion formed at the peripheral end. Is also formed on the outer peripheral side so as to surround the outer periphery of the first opening and partitioning the region of the second opening, and is formed in the second opening and formed using a wet coating method. A light emitting medium layer including at least one wet coat layer and an organic light emitting layer, and a second electrode formed opposite to the first electrode with the light emitting medium layer interposed between the second openings. The film thickness of at least the first insulating layer formed on the first electrode is Among the wet coat layers, the first wet coat layer formed on the most first electrode side is thinner than the film thickness at the position facing the first electrode and is thinner than the first electrode film thickness. Features.

In the organic EL display element according to the aspect of the present invention, the first insulating layer preferably has a thickness of ½ or less of the thickness of the first wet coat layer.
In the organic EL display element according to the aspect of the present invention, the first insulating layer preferably has a thickness of ½ or less of the thickness of the first electrode.
In the organic EL display element which is an aspect of the present invention, the distance between the peripheral edge of the first electrode and the first insulating layer portion formed on the peripheral edge and the second insulating layer on the outer periphery is 1 μm or more. It is preferable that it is 20 micrometers or less.

An organic EL display device according to another aspect of the present invention includes any one of the organic EL display elements shown in the above aspect as a display element.
The organic EL display element manufacturing method according to another aspect of the present invention is the organic EL display element manufacturing method described in the above aspect, wherein the wet coating method for forming the at least one wet coat layer is a printing method. It is characterized by being.

The printing method of the aspect of the present invention is preferably a relief printing method.
Another aspect of the present invention is a method for manufacturing a machine EL display device, which is a method for manufacturing an organic EL display device including an organic EL display element as a display element. It is manufactured using the manufacturing method of the organic EL display element shown in (5).

  According to the aspect of the present invention, it is possible to obtain an organic EL display element in which the occurrence of defective light emission is suppressed by further realizing flattening of the organic layer in the light emitting region.

It is a schematic sectional drawing which shows an example of the pixel in the conventional organic EL display element. It is a schematic sectional drawing which shows an example of the organic electroluminescent display element which concerns on embodiment of this invention. It is a schematic sectional drawing which shows an example of the pixel of the organic electroluminescent display element which concerns on embodiment of this invention. It is the schematic which shows an example of arrangement | positioning of the 1st electrode and partition of the pixel of the organic EL display element which concern on embodiment of this invention. FIG. 5 is a schematic cross-sectional view taken along line A-A ′ of FIG. 4, illustrating an example of a substrate with TFTs according to an embodiment of the present invention. It is the schematic which shows an example of the relief printing apparatus which concerns on embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment, the same reference numerals are assigned to the same components.
In the present embodiment, a case will be described in which the present invention is applied with the active matrix driving type organic EL display element 10 shown in FIG. 2 applied to the organic EL display device as a bottom emission type. However, the present invention is not limited to this. For example, the present invention can be applied to a passive matrix driving type organic EL element, and is implemented by both a bottom emission type in which light is extracted from the first electrode side and a top emission type in which light is extracted from the second electrode side. It is possible.

  FIG. 3 is an example of a schematic cross-sectional view showing one pixel constituting the active matrix driving type organic EL element 10 of the present embodiment in FIG. FIG. 4 is a drawing showing an example of the arrangement of the first electrode and partition walls of one pixel constituting the active matrix driving type organic EL element 10 of the present embodiment.

Hereinafter, an active matrix drive organic EL display element 10 to which the present invention is applied will be described with reference to FIGS. 2, 3, and 4.
As shown in FIG. 3, the pixel unit 100 of the active matrix driving organic EL display element 10 of the present embodiment is formed on a TFT substrate 101 including a thin film transistor TFT (not shown) provided for each pixel, and on the substrate 101. A first opening 110 is formed on the first electrode 102 so as to cover the first electrode 102 (anode) and the peripheral end of the first electrode pixel portion 112 of the first electrode 102 (see FIG. 4). The first insulating layer 103, the second opening 111 surrounding the outer periphery of the first opening 110, the second insulating layer 104 as a partition for separating the pixels, and the second opening 111 are formed in the second opening 111. And a second electrode 106 (cathode) formed on the light emitting medium layer 105 and facing the first electrode 102. A gap is formed between the portion of the first insulating layer 103 formed at the peripheral edge of the first electrode and the second insulating layer 104 on the outer periphery thereof.

Note that the peripheral edge of the first electrode pixel portion 112 in FIG. 4 is a region including the portion of the first insulating layer 103 formed at the peripheral edge of the first electrode 102, and the first insulating layer 103 is omitted in FIG. It represents.
The light emitting medium layer 105 is a layer including at least an organic light emitting layer, and one or more layers are wet coat layers formed by a wet coating method. The organic light emitting layer may be a wet coat layer. The light emitting medium layer 105 is preferably a plurality of layers such as a hole transport layer, an electron block or hole injection layer, an interlayer, an organic light emitting layer, an electron injection layer, a hole block layer, and an electron transport layer on the first electrode. What consists of these is preferable.

  In the present embodiment, the EL light emitting region is in a range defined by the first opening 110, and the wet coating layer of the light emitting medium layer formed by the wet coating method is formed in the second opening 111. Is done. Similar to the conventional structure shown in FIG. 1, the wet coat layer is thicker on the second insulating layer 104 side than the center of the opening due to the influence of the second insulating layer 104. On the other hand, in this embodiment, only the flat film thickness portion can be defined as the light emitting region by forming the first opening 110 with the first insulating layer 103 so that the thick film portion is not included in the light emitting region. it can. At this time, the film thickness d1 of the first insulating layer is d1 <d2 with respect to the film thickness d2 of the first wet coat layer 105 (a) formed on the most side of the first electrode 102 by the wet coating method. Thus, deterioration of flatness in the first opening 110 due to the influence of the first insulating layer 103 can be suppressed. More preferably, d1 <(d2 / 2). Here, the comparison of the film thickness is the thickness of the portion facing the first electrode 102 in the thickness direction of the first electrode.

  In the structure of this embodiment, the peripheral edge of the first electrode pixel portion 112 formed on the first electrode 102 is inside the opening formed by the second insulating layer 104, and the film thickness d3 of the first electrode 102 is set. By setting the film thickness d1 of the first insulating film 103 to be d1 <d3, a groove is formed due to the presence of a film thickness difference generated between the peripheral edge of the first electrode 102 and the second insulating layer 104. Is done. As a result, when the film is formed by the wet coating method, an increase in the film thickness on the second insulating layer 104 side is suppressed by the groove, and the influence of the second insulating layer 104 is compared with the conventional structure shown in FIG. It is possible to move the thick film region to the outside and widen the film thickness flat region of the wet coating layer. The relationship between the film thickness d3 of the first electrode 102 and the film thickness d1 of the first insulating film 103 is more preferably d1 <(d3 / 2).

In FIG. 4, reference numeral 113 denotes a first electrode connection portion.
As a result of adopting the above-described configuration, an organic EL display in which the light emitting region defined by the first opening 110 is widened in the second opening 111 and the light emitting medium layer 105 is flat in the thickness in the first opening 110. An element can be obtained. Note that the first insulating film 103 suppresses current leakage when the layer formed on the first electrode 101 is formed of an inorganic film, light emission abnormality due to a shape defect at the peripheral edge of the first electrode 102, and the like. The thickness of the first insulating film 103 is preferably not less than 1 nm and not more than 30 nm.

Next, a substrate (back plane) 101 used in the active matrix driving type organic EL display element 10 according to the present embodiment will be described with reference to FIG. FIG. 5 shows a cross-sectional view taken along the line AA ′ of FIG.
As shown in FIG. 5, a thin film transistor TFT and a first electrode 102 of the organic EL display element 10 are provided on a substrate (back plane) 101 used for the active matrix driving type organic EL display element 10 of the present embodiment. The drain electrode 207 of the thin film transistor TFT and the first electrode 102 of the organic EL display element 10 are electrically connected via the first electrode connection portion 113. A TFT substrate (back plane) 101 on which the thin film transistor TFT and the active matrix driving type organic EL display element 10 formed thereon is formed is supported by a support 202.

  As the support 202, any material can be used as long as it is a member having mechanical strength and insulation and excellent dimensional stability. For example, plastic films and sheets such as glass, quartz, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, etc., or oxidation to these plastic films and sheets Metal oxides such as silicon and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride and aluminum nitride, metal oxynitrides such as silicon oxynitride, acrylic resins and epoxy resins Translucent base material with a single layer or laminated polymer resin film such as silicon resin or polyester resin, metal foil such as aluminum or stainless steel, sheet or plate, and aluminum film on the plastic film or sheet. It can be used beam, copper, nickel, stainless steel and metal film non-translucent substrate as a laminate of such.

  Moreover, what is necessary is just to select the translucency of the support body 202 according to which surface takes out light. The support 202 made of these materials is subjected to moisture-proof treatment or hydrophobic treatment by forming an inorganic film or applying a fluororesin in order to prevent moisture from entering the organic EL display element 10. It is preferable. In particular, in order to avoid intrusion of moisture into the organic light emitting medium layer 105, it is preferable to reduce the moisture content and gas permeability coefficient in the support 202.

  As the thin film transistor TFT provided over the support 202, a thin film transistor having a known structure can be used. Specifically, as shown in FIG. 5, a thin film transistor mainly including a region to be a source electrode 206, a region to be a drain electrode 207, an active layer 203 in which a channel region is formed, a gate insulating film 204, and a gate electrode 205. Is mentioned. The structure of the thin film transistor TFT is not particularly limited, and examples thereof include a stagger type, an inverted stagger type, a top gate type, a bottom gate type, and a coplanar type. In FIG. 5, reference numeral 208 denotes a scanning line, and reference numeral 209 denotes an interlayer insulating film.

The active layer 203 is not particularly limited, and examples thereof include inorganic semiconductor materials such as amorphous silicon, polycrystalline silicon, microcrystalline silicon, cadmium selenide, thiophene oligomers, poly (p-ferylene vinylene), and the like. The organic semiconductor material can be used. These active layers 203 are formed by, for example, laminating amorphous silicon by plasma CVD and ion doping; forming amorphous silicon by LPCVD using SiH ₄ gas, and crystallizing amorphous silicon by solid phase growth. After obtaining polysilicon, a method of ion doping by ion implantation; amorphous silicon is formed by LPCVD using Si ₂ H ₆ gas and PECVD using SiH ₄ gas, and by a laser such as an excimer laser After annealing and crystallizing amorphous silicon to obtain polysilicon, a method of ion doping by ion doping (low temperature process); polysilicon is deposited by low pressure CVD or LPCVD, and thermally oxidized at 1000 ° C. or higher Gate break Forming a film 204, a gate electrode 205 of the n ⁺ polysilicon is formed thereon, then, a method of ion doping (high temperature process), and the like by an ion implantation method.

As the gate insulating film 204, a film normally used as a gate insulating film can be used. For example, SiO ₂ formed by PECVD, LPCVD, etc., SiO obtained by thermally oxidizing a polysilicon film ₂ etc. can be used. As the gate electrode 205, a material usually used as a gate electrode can be used. For example, a metal such as aluminum or copper, a refractory metal such as titanium, tantalum, or tungsten, polysilicon, or a silicide of a refractory metal. And polycide. As the source electrode 206 and the drain electrode 207, those normally used as the source electrode and the drain electrode can be used. For example, metals such as aluminum and copper, titanium, tantalum, tungsten, and the like can be used.

Note that the thin film transistor TFT may have a single gate structure, a double gate structure, or a multi-gate structure in which three or more gate electrodes 205 are formed. Moreover, you may have a LDD structure and an offset structure. Further, two or more thin film transistors may be arranged in one pixel.
The active matrix driving type organic EL display element 10 according to the present embodiment needs to be connected so that the thin film transistor TFT functions as a switching element of the organic EL display element 10, and the source electrode 206 of the thin film transistor TFT and the pixel unit 100. The pixel electrode (first electrode 102) is electrically connected.

  Next, the first electrode 102 of the pixel portion 100 that electrically connects the source electrode 206 of the thin film transistor TFT will be described. As shown in FIG. 3, the first electrode 102 is formed on the TFT substrate 101, and patterning is performed according to the pixel to be formed. The patterned first electrode 102 is partitioned by a first insulating layer 103 and a second insulating layer 104, which will be described later, and becomes the first electrode 102 corresponding to each pixel.

  Examples of the material of the first electrode 102 include metal composite oxides such as ITO (indium tin composite oxide), indium zinc composite oxide and zinc aluminum composite oxide, metal materials such as gold and platinum, and these metal oxides. Alternatively, a single layer or a laminate of fine particle dispersion films in which fine particles of a metal material are dispersed in an epoxy resin or an acrylic resin can be used. When the first electrode 102 is used as an anode, it is preferable to select a material having a high work function such as ITO. In the case of a so-called bottom emission structure in which light is extracted from below, it is necessary to select a light-transmitting material. If necessary, in order to reduce the wiring resistance of the first electrode 102, a metal material such as copper or aluminum may be provided as an auxiliary electrode.

  The first electrode 102 can be formed by 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, or a sputtering method, depending on the material for forming the first electrode 102. Alternatively, a wet film forming method such as a gravure printing method or a screen printing method can be used. As a patterning method for the first electrode 102, an existing patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method is used depending on the material for forming the first electrode 102 and the film forming method. be able to. In the case where a substrate on which a thin film transistor TFT is formed is used as a substrate, it is formed so as to be conductive corresponding to the lower layer pixel.

Next, a method for forming the first insulating layer 103 and the second insulating layer 104 of the pixel portion 100 will be described.
The first insulating layer 103 of the pixel unit 100 according to the present embodiment is formed so as to cover the peripheral end of the first electrode pixel unit 112 and partition the first opening 110 corresponding to the light emitting region of the pixel. The second insulating layer 104 is formed at least 1.0 μm outside the peripheral end portion of the first electrode pixel portion 112 (position including the first insulating film portion formed on the first pixel electrode), and the second opening 111 It is necessary to arrange so that the ratio of the film thickness flat region of the wet coating layer is high, and it is more preferably 1 μm or more and 20 μm or less.

As a method for forming the first insulating layer 103 and the second insulating layer 104, an inorganic film is uniformly formed on a substrate on which the first electrode 102 is formed on the TFT substrate 101, and a resist is used. Examples thereof include a method of performing dry etching after masking, and a method of laminating a photosensitive resin on a substrate to form a predetermined pattern by photolithography.
The width of the first insulating layer 103 covering the pixel portion 112 of the first electrode (the distance from the end of the first opening 110 to the end of the first electrode pixel 112 in FIG. 3) is the first opening 110. Is preferably 3 μm or less in order to increase the width of the film.

  Here, the film thickness d1 of the first insulating layer 103 is the film thickness d2 of the layer 105 (a) formed closest to the first electrode 102 among the wet coat layers forming the light emitting medium layer 105, and the first electrode. D1 <d2 and d1 <d3 between the film thickness d3 of 102. More preferably, d1 <(d2 / 2) and d1 <(d3 / 2). More preferably, the film thickness of the first insulating layer 103 is not less than 1 nm and not more than 30 nm after d1, d2, and d3 satisfy the above relationship.

  The height of the second insulating layer 104 is not less than 0.1 μm and not more than 10 μm, preferably not less than 0.5 μm and not more than 2 μm. If the second insulating layer 104 is too high, the formation and sealing of the second electrode 108 is hindered. If the second insulating layer 104 is too low, the periphery of the pixel electrode (first electrode 102) cannot be covered, or adjacent to the organic light emitting layer or the like when formed. This is because they are short-circuited or mixed with pixels.

Next, a method for forming the light emitting medium layer 105 such as the organic light emitting layer of the pixel unit 100 according to the present embodiment will be described.
As an example of the light emitting medium layer 105, a structure in which a hole injection layer, an interlayer, a light emitting layer, and an electron transport layer are sequentially provided can be given. Here, among the wet coat layers constituting the light emitting medium layer 105, the layer 105 (a) formed closest to the first electrode 102 is used when the constituent layer of the light emitting medium layer is formed of an inorganic film or an organic film. Since the film may be formed by a vacuum film formation method such as vapor deposition, the first wet coat layer 105 (a) of the light emitting medium layer is not necessarily the first layer formed on the first electrode 102. .

The hole injection layer has a function of injecting holes from the first electrode. The physical property value of the hole injection layer preferably has a work function equal to or higher than that of the pixel electrode. This is because holes are efficiently injected from the pixel electrode to the interlayer. Although it varies depending on the material of the pixel electrode, 4.5 eV or more and 6.5 eV or less can be used. When the pixel electrode is ITO or IZO, 5.0 eV or more and 6.0 eV or less can be suitably used. The specific resistance of the hole injection layer is preferably 1 × 10 ³ to 2 × 10 ⁶ Ω · m, more preferably 5 × 10 ³ to 1 × 10 ⁶ Ω · m, with a film thickness of 30 nm or more. m. Further, in the bottom-etched structure, emitted light is extracted from the pixel electrode side. If the light transmittance is low, the extraction efficiency is lowered. Therefore, the total average in the visible light wavelength region is preferably 75% or more, and if it is 85% or more. It can be preferably used.

As a material constituting the hole injection layer, for example, a polymer material such as polyaniline, polythiophene, polyvinylcarbazole, a mixture of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid can be used. In addition, a conductive polymer having a conductivity of 10 ⁻² S / cm or more and 10 ⁻⁶ S / cm or less can be preferably used. The polymer material can be used in a film forming process by a wet method. For this reason, it is preferable to use a polymer material when forming the hole injection layer. Such a polymer material is dispersed or dissolved in water or a solvent and used as a dispersion or solution.

When an inorganic material is used as the hole injecting material, the inorganic materials include Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeOx (x ≧ 0.1), NiO, CoO, Pr ₂ O ₃ , Ag _2. Vacuum deposition using O, MoO, Bi ₂ O ₃ , ZnO, TiO ₂ , SnO ₂ , ThO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO _2, etc. Or by sputtering. However, the material is not limited to these.

After forming the hole injection layer, an interlayer is formed. Polymers containing aromatic amines such as polyvinyl carbazole or derivatives thereof, polyarylene derivatives having aromatic amines in the side chain or main chain, arylamine derivatives, triphenyldiamine derivatives, etc. as materials used in forming this interlayer Etc. These materials are dissolved or dispersed in a solvent and formed by various wet coating methods using a spin coater or the like, various printing methods such as a relief printing method and an ink jet method. In the inorganic _{materials, Cu 2 O, Cr 2 O} 3, Mn 2 O 3, NiO, CoO, Pr 2 O 3, Ag 2 O, MoO 2, ZnO, TiO 2, V 2 O 5, Nb 2 O 5, Examples thereof include transition metal oxides such as Ta ₂ O ₅ , MoO ₃ , WO ₃ and MnO ₂ , and inorganic compounds containing one or more of these nitrides and sulfides. However, the present invention is not limited to these.

  After forming the interlayer, an organic light emitting layer is formed. This organic light emitting layer is a layer that emits light when an electric current is passed, and organic light emitting materials that form the organic light emitting layer are, for example, coumarin-based, perylene-based, pyran-based, anthrone-based, porphyrene-based, quinacridone-based, N, N Dispersing luminescent dyes such as' -dialkyl-substituted quinacridone, naphthalimide-based, N, N'-diaryl-substituted pyrrolopyrrole, iridium complex in polymers such as polystyrene, polymethyl methacrylate, polyvinyl carbazole, etc. , Polyarylene-based, polyarylene vinylene-based, and polyfluorene-based polymer materials are exemplified, but the present invention is not limited thereto.

  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, a wet coating method is preferable, and an existing film forming method such as an ink jet method, a nozzle coating method, a letterpress printing method, a gravure printing method, or a screen printing method can be used.
Here, in this embodiment, although the hole injection layer, the interlayer, and the organic light emitting layer are formed as the light emitting medium layer 105, these layer configurations are preferably selected as appropriate according to the material to be used. For example, an electron transport layer and / or an electron injection layer may be further provided between the organic light emitting layer and the second electrode 106 as the cathode.

Next, a relief printing apparatus 300 will be described with reference to FIG. 6 as an example of an apparatus used when forming a hole transport layer and an organic light emitting layer when using an organic material.
FIG. 6 shows a TFT substrate 101 on which the pixel electrode (first electrode 102), the first insulating layer 103, the second insulating layer 104 as a partition, for example, a hole transport layer made of an inorganic material, is formed. The printing plate 307 is a relief printing apparatus 300 for pattern-printing an organic light-emitting ink made of an organic light-emitting material on the TFT substrate 101.

  The relief printing apparatus 300 includes an ink tank 301, an ink chamber 302, an anilox roll 303, and a printing copper 306 on which a relief printing plate 305 having an image line portion formed in a convex shape is mounted. The ink tank 301 contains an organic light emitting ink diluted with a solvent, and the organic light emitting ink is fed into the ink chamber 302 from the ink tank 301. The anilox roll 303 is rotatably supported in contact with the ink supply unit of the ink chamber 302. A convex image line portion is formed on the plate 305 in advance according to the pattern of the pixels 100 formed on the TFT substrate 101 in advance.

  Along with the rotation of the anilox roll 303, the organic light emitting ink is supplied to the surface of the anilox roll 303 by the ink chamber 302, and the ink layer 304 of the supplied organic light emitting ink is formed with a uniform film thickness. The ink of the ink layer 304 is transferred to a convex portion as an image line portion of a plate 305 mounted on a plate cylinder 306 that is driven to rotate in the vicinity of the anilox roll 303, and is a printed substrate placed on a flat table 308. Pattern printing is performed on the second opening 111 surrounded by the second insulating layer 104 as a partition wall 307.

  Next, the second electrode 106 is formed. When the second electrode 106 is used as a cathode, a substance having a high electron injection efficiency into the organic light emitting layer and a low work function is used. Specifically, a single metal such as Mg, Al, or Yb is used, or a compound such as Li, oxidized Li, or LiF is sandwiched by several nanometers at the interface in contact with the light emitting medium, and Al or Cu having high stability and conductivity is laminated. You may use it. 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 of Cu and a metal element may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.

As a method for forming the second electrode 106, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on a material to be the second electrode 106.
In order to protect the organic EL element from oxygen and moisture from the outside, a passivation layer may be formed on the counter electrode. The passivation layer includes metal oxides such as silicon oxide and aluminum oxide, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride, aluminum nitride and carbon nitride, and metal acids such as silicon oxynitride. A laminated film of a metal carbide such as nitride or silicon carbide, and a polymer resin film such as an acrylic resin, an epoxy resin, a silicone resin, or a polyester resin may be used as required. In view of the above, it is preferable to use silicon oxide, silicon oxynitride, or silicon nitride. Furthermore, by using a laminated film or a gradient film having a variable film density, a film having both step coverage and barrier properties can be obtained. .

As a method for forming the passivation layer, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or a CVD method can be used depending on the material. The CVD method is preferably used because the film density and film composition can be easily varied depending on the step coverage surface and the film formation conditions. As the CVD method, a thermal CVD method, a plasma CVD method, a catalytic CVD method, a VUV-CVD method, or the like can be used. In addition, as a reaction gas in the CVD method, a gas such as N ₂ , O ₂ , NH ₃ , H ₂ , N ₂ O is added to an organic silicon compound such as monosilane, hexamethyldisilazane (HMDS), or tetraethoxysilane. The film density may be changed by changing the gas flow rate of silane or the like, or the plasma power, if necessary. Hydrogen or carbon may be added to the film by the reactive gas used. It can also be contained.

The thickness of the passivation layer is preferably 5 μm or less, more preferably 1 μm or less.
The active matrix driving type organic EL display element 10 can emit light by sandwiching a light emitting material between electrodes and passing a current, but the organic light emitting material is easily deteriorated by moisture and oxygen in the atmosphere. . For this reason, normally, a sealing body (not shown) for shielding from the outside is provided. The sealing body can be manufactured, for example, by providing a resin layer on a sealing material.

The sealing material 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 1 × 10 ⁻⁶ g / m ² / day or less.

  As an example of the material of the resin layer, a photo-curing adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin, or an ethylene ethyl acrylate (EEA) made of epoxy resin, acrylic resin, silicon resin, or the like Examples thereof include acrylic resins such as polymers, vinyl resins such as ethylene vinyl acetate (EVA), thermoplastic resins such as polyamide and synthetic rubber, and thermoplastic adhesive resins such as acid-modified products of polyethylene and polypropylene. Examples of methods for forming a resin layer on a sealing material include solvent solution method, extrusion lamination method, melting / hot melt method, calendar method, nozzle coating method, screen printing method, vacuum laminating method, hot roll laminating method, etc. Can be mentioned. A material having a hygroscopic property or an oxygen absorbing property may be contained as necessary. Although the thickness of the resin layer formed on a sealing material is arbitrarily determined by the magnitude | size and shape of the organic electroluminescent display element 10 to seal, about 5 micrometers-about 500 micrometers are desirable. In addition, although formed as a resin layer on the sealing material here, it can also be formed directly on the organic EL display element side.

  Finally, the organic EL display element 10 and the sealing body are bonded together in a sealing chamber. When the sealing body has a two-layer structure of a sealing material and a resin layer, and a thermoplastic resin is used for the resin layer, it is preferable to perform only pressure bonding with a heated roll. When a thermosetting adhesive resin is used, it is preferable to perform heat curing at a curing temperature after pressure bonding with a heated roll. In the case where a photocurable adhesive resin is used, curing can be performed by further irradiating light after pressure bonding with a roll.

The Example based on this invention and a comparative example are shown below.
Example 1
As the substrate, an active matrix substrate including a thin film transistor (TFT) functioning as a switching element provided on a support and a pixel electrode formed thereabove was used. A substrate having a size of 200 mm × 200 mm, a diagonal of 5 inches, and a pixel number of 320 × 240 is arranged in the center.

ITO was used as a pixel electrode. ITO was formed by sputtering, the film thickness was 40 nm, and the ITO film was patterned by photolithography and etching with an acid solution. The ITO film has a pixel portion and a connection portion, and is connected to the TFT at the connection portion.
Next, a first insulating layer was formed so as to cover the peripheral edge of the electrode pixel portion provided on the active matrix substrate and partition the pixel. The first insulating layer is formed by uniformly forming an inorganic material with a thickness of 10 nm on the active matrix substrate by vacuum deposition, masking with a resist, and covering the peripheral edge of the electrode pixel portion by 0.5 μm to form a light emitting region. A pattern was formed by a dry etching method so as to define the first opening for forming the film.

A second insulating layer was formed as a partition wall separating the pixels, and a second opening was formed. The second insulating layer was formed by using a positive resist and forming the entire surface of the substrate with a thickness of 2 μm by a spin coater method, followed by patterning using a photolithography method. The opening side end portion of the second insulating layer was set to be 3.5 μm outside the peripheral end of the electrode pixel portion.
Next, molybdenum oxide (MoOx) having a thickness of 10 nm is stacked on the surfaces of the electrode and the first insulating layer and the second insulating layer as a hole injecting material by a vacuum deposition method to form a hole injecting layer. did. The distance between the evaporation source and the substrate was set to 300 mm, and the angle between the vapor deposition source direction and the normal direction of the substrate surface from the center of the substrate surface was set to 0 °.

  Next, using an ink in which a polyvinyl carbazole derivative, which is a hole transport material, is dissolved in toluene so as to have a concentration of 0.5%, an active matrix substrate formed up to the hole injection layer described above is used as a substrate to be printed. It was set in a relief printing apparatus, and the hole transport layer was printed by the relief printing method in accordance with the line pattern just above the second opening sandwiched between the second insulating layers. The thickness of the hole transport layer after printing and drying was 30 nm.

  Next, using an organic light emitting ink in which a polyphenylene pinylene derivative, which is an organic light emitting material, is dissolved in toluene so as to have a concentration of 1%, an active matrix substrate on which the above-described hole transport layer is formed is used as a substrate to be printed. Setting was performed in a letterpress printing apparatus, printing was performed with a target film thickness of 80 nm at the center of the pixel by letterpress printing in accordance with the line pattern just above the second opening sandwiched between the second insulating layers.

  Next, a Ba film was formed as a counter electrode by a vacuum evaporation method to a film thickness of 4 nm using a metal mask, and then an Al film was formed by a vacuum evaporation method to a film thickness of 150 nm using a metal mask. Then, a cap-type sealing glass and an adhesive are placed so as to cover the light emitting region, and the adhesive is thermally cured at about 90 ° C. for 1 hour, and hermetically sealed to produce an active matrix driving type organic EL display element 10. did.

  As a result of evaluating the active matrix driving type organic EL element thus created, as shown in Table 1, a flat film thickness region having a film thickness distribution within which the film thickness distribution is within 10% of the target film thickness at the center of the pixel is obtained. It was 100% in the first opening, and it was confirmed that the film thickness was flat in the light emitting region. The flat film thickness region in the second opening was 87%. The light emission state was also good.

(Comparative Example 1)
As a comparative example of Example 1, the pattern shape of the pixel electrode was changed, and the pixel electrode was widened so that the peripheral edge of the pixel electrode was covered with the second insulating layer. Other than that, an organic EL display element was prepared under the same conditions as in Example 1. In Comparative Example 1, as shown in Table 1, a flat film thickness region having a film thickness distribution within a target film thickness of + 10% in the central portion of the pixel is 90% in the first opening, and the second It became 73% in the opening. The light emission state was good.

(Comparative Example 2)
As a comparative example of Example 1, the thickness of the first insulating layer was set to 50 nm. Other than that, an organic EL display element was prepared under the same conditions as in Example 1. In Comparative Example 2, as shown in Table 1, a flat film thickness region having a film thickness distribution within a target film thickness of + 10% in the center of the pixel is 75% in the first opening, and the second It became 58% in the opening. The outer peripheral part inside the pixel did not emit light, resulting in cat-like light emission.

01 Substrate 02 First electrode 03 Partition 04 Light emitting medium layer 05 Second electrode
06 EL emission region 10 Active matrix driving type organic EL display element 100 Pixel portion 101 of active matrix driving type organic EL display element TFT substrate (back plane)
102 1st electrode (pixel electrode)
103 first insulating layer 104 second insulating layer 105 light emitting medium layer 105 (a) first wet coat layer 106 second electrode 110 first opening (light emitting region)
111 Second opening 112 First electrode pixel portion 113 First electrode connection portion 202 Support 203 Active layer 204 Gate insulating film 205 Gate electrode 206 Source electrode 207 Drain electrode 208 Scan line 210 Insulating layer 300 Topographic printing apparatus 301 Ink tank 302 Ink chamber 303 Anilox roll 304 Ink layer 305 Plate 306 Plate cylinder 307 Printed substrate 308 Flat stand

Claims (8)

A substrate, a first electrode formed on the substrate,
A first insulating layer which is formed on at least the peripheral edge of the first electrode and around the first electrode and defines a region of a first opening corresponding to a light emitting region of a pixel on the first electrode;
The first electrode is formed so as to surround the outer periphery of the first opening on the outer peripheral side with respect to the peripheral end of the first electrode and the first insulating layer portion formed at the peripheral end. Two insulating layers;
A light emitting medium layer including one or more wet coat layers and an organic light emitting layer formed in the second opening and formed using a wet coating method;
A second electrode formed to face the first electrode with the luminescent medium layer interposed therebetween with respect to the second opening,
The film thickness of at least the first insulating layer formed on the first electrode is greater than the film thickness at the position facing the first electrode in the first wet coat layer formed closest to the first electrode among the wet coat layers. Is an organic EL display element characterized by being a thin film and being thinner than the thickness of the first electrode.   2. The organic EL display element according to claim 1, wherein the film thickness of the first insulating layer is not more than ½ of the film thickness of the first wet coat layer.   3. The organic EL display element according to claim 1, wherein the film thickness of the first insulating layer is ½ or less of the film thickness of the first electrode.   2. The space between the peripheral edge of the first electrode and the first insulating layer portion formed on the peripheral edge and the second insulating layer on the outer periphery thereof is 1 μm or more and 20 μm or less. The organic EL display element according to any one of claims 3 to 4.   An organic EL display device comprising the organic EL display element according to any one of claims 1 to 4 as a display element. It is a manufacturing method of the organic electroluminescent display element of any one of Claims 1-4, Comprising:
A method for manufacturing an organic EL display element, wherein the wet coating method for forming the at least one wet coat layer is a printing method.   The method for producing an organic EL display element according to claim 6, wherein the printing method is a relief printing method. A method of manufacturing an organic EL display device including an organic EL display element as a display element,
A method for producing an organic EL display device, wherein the organic EL display element is produced using the method for producing an organic EL display element according to claim 6.

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