JP2010027451A - Organic el display device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL display device that can be efficiently manufactured at low cost and has excellent display quality, and to provide a manufacturing method thereof. <P>SOLUTION: The organic EL display device includes: a first electrode; an organic EL layer formed on the first electrode; a second electrode that is formed on the organic EL layer to have a smaller area than the lower first electrode; a sealing film that is formed to cover the second electrode and formed with a contact hole that reaches the second electrode; and a conductive film that is formed on the sealing film to be continuous with the second electrode via the contact hole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In recent years, organic EL displays have been put into practical use as next-generation displays. The organic EL display is configured by laminating a hole transport layer, a light emitting layer, an electron transport layer, and the like between a first electrode (anode) and a second electrode (cathode), and includes a plurality of organic EL layers. ing. By passing a current between the first electrode and the second electrode, the light emitting layer sandwiched between them emits light with an intensity corresponding to the current. A display capable of displaying an image or the like can be configured by devising the shape of either the first electrode or the second electrode, or both electrodes. In general, an organic EL display may be configured by forming a first electrode in a dot matrix according to a pixel and forming a second pattern as a second electrode. Further, the organic EL display may be configured by forming the first electrode and the second electrode in a plurality of stripes, making them perpendicular to each other, and forming a pixel at the intersection.

  In the organic EL display having such a configuration, when the first electrode and the second electrode are in contact with each other in the pixel, an electrical short circuit occurs, which causes a problem that the display quality of the display is deteriorated. For this reason, in general, an insulating edge cover is provided at the pattern end portion or the like of the first electrode, thereby suppressing contact between the first electrode and the second electrode.

Further, as a technique for preventing an electrical short circuit between the first electrode and the second electrode, for example, Patent Document 1 discloses a capacitor that is provided on an upper part of a substrate and includes at least two electrodes facing each other so as to be insulated from each other. In US Pat. No. 6,057,836, an electrode located in the upper part has a smaller area than an electrode located in the lower part.
JP 2005-159290 A

  However, if an insulating edge cover is provided at the end portion of the first electrode as in the above-described general organic EL display, the manufacturing cost is increased correspondingly, and this causes a reduction in throughput during production.

  Further, as in Patent Document 1, the second electrode is simply formed in a smaller area than the first electrode, and the contact extraction pattern with the second electrode is formed so as to overlap the first electrode pattern, and the external circuit and the second electrode are formed. Is connected, the possibility of short-circuiting at the portion where the extraction pattern overlaps with the periphery of the first electrode pattern is increased, which causes a problem in display quality.

  The present invention has been made in view of such various points, and an object of the present invention is to provide an organic EL display device having excellent manufacturing quality and manufacturing efficiency and excellent display quality, and a manufacturing method thereof. That is.

  An organic EL display device according to the present invention includes a first electrode, an organic EL layer formed on the first electrode, a second electrode formed on the organic EL layer and having a smaller area than the first electrode below, A sealing film provided to cover the second electrode and having a contact hole reaching the second electrode; a conductive film formed on the sealing film and electrically connected to the second electrode through the contact hole; It is provided with.

  In the organic EL display device according to the present invention, a plurality of pixel regions arranged in a matrix with the first electrode and the second electrode are defined, and a plurality of contact holes for the sealing film are formed in each pixel region. It may be formed.

  Furthermore, the organic EL display device according to the present invention includes a switching device including an insulating substrate and a switching element formed on the insulating substrate and electrically connected to the first electrode below the first electrode. An element substrate may be provided.

  In the organic EL display device according to the present invention, the organic EL layer may include a coffee stain portion. Here, the coffee stain part is a drop of a droplet after drying, which is caused when the concentration of the vicinity of the edge of the droplet increases as the evaporation proceeds (so-called coffee stain phenomenon). A raised edge. Here, the inside of the coffee stain portion of the dried droplet has a depressed shape.

  The method for manufacturing an organic EL display device according to the present invention includes a first step of preparing a first electrode, a second step of forming an organic EL layer on the first electrode, and a lower first on the organic EL layer. A third step of forming a second electrode having a smaller area than the electrode; a fourth step of forming a sealing film so as to cover the second electrode; and forming a contact hole reaching the second electrode in the sealing film. A fifth step and a sixth step of forming a conductive film electrically connected to the second electrode through the contact hole on the sealing film are provided.

  Moreover, the manufacturing method of the organic electroluminescent display apparatus which concerns on this invention may form the organic electroluminescent layer provided with the coffee stain part on the 1st electrode using the wet coating method at a 2nd process.

  ADVANTAGE OF THE INVENTION According to this invention, manufacturing cost and manufacturing efficiency are favorable, and the organic EL display apparatus provided with the outstanding display quality and its manufacturing method can be provided.

  Hereinafter, a configuration of an organic EL display device according to an embodiment of the present invention and a manufacturing method thereof will be described in detail based on the drawings. The present invention is not limited to the following embodiment.

(Embodiment 1)
(Configuration of the organic EL display device 10)
FIG. 1 is a plan view of an organic EL display device 10 according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view taken along line AA ′ in FIG. 1 and shows an organic EL element 12 formed on a thin film transistor (TFT) 11 as a switching element. In FIG. 1, peripheral circuit portions such as a gate driver and a conductive film extraction terminal portion are omitted. In addition, although omitted in dot notation, in the organic EL display device 10, a plurality of pixel regions 15 defined by the first electrode 13 and the second electrode 14 of the organic EL element 12 are arranged in a matrix.

  The organic EL display device 10 includes a TFT substrate 16 (switching element substrate), a plurality of first electrodes 13 (anodes) arranged in a predetermined arrangement (for example, in a matrix) on the TFT substrate 16, and a plurality of first electrodes. An organic EL layer 17 formed on each of the first electrodes 13, a second electrode 14 formed on the organic EL layer 17, a sealing film 18 formed so as to cover the second electrode 14, and a sealing A conductive film 19 formed on the stop film 18, and these are sealed with a sealing resin and a sealing glass (not shown) in an inert gas atmosphere.

  The TFT substrate 16 includes an insulating substrate 20, a TFT 11 electrically connected to each of the plurality of first electrodes 13 arranged in a predetermined arrangement, and a source electrode and a gate electrode electrically connected to the TFT 11. And a planarizing film 21 (interlayer insulating film) covering the TFT 11.

The insulating substrate 20 has a function of ensuring the mechanical durability of the organic EL element 12 and a function of suppressing water and oxygen from entering the organic EL layer 17 from the outside. As the substrate material, inorganic materials such as glass and quartz, plastics such as polyethylene terephthalate, ceramics such as alumina, and the like can be used. Also, one side of a metal substrate such as aluminum or iron is coated with an insulating material such as SiO ₂ (silica gel) or an organic insulating material, or the surface of a metal substrate such as aluminum or iron is anodized. An insulating substrate may be used. In the case where the organic EL element 12 is a bottom emission type in which light emission of the organic EL element 12 is extracted from the insulating substrate 20 side, that is, the surface opposite to the element forming surface, the insulating substrate 20 is made of glass, plastic, or the like. It is preferable to use a material having a high light transmittance.

  The first electrode 13 (anode) has a function of injecting holes into the organic EL layer 17. The first electrode 13 is more preferably formed of a material having a large work function. This is because the hole injection efficiency into the organic EL layer 17 can be improved by forming the first electrode 13 with a material having a large work function.

As the constituent material of the first electrode 13, silver (Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni), tungsten (W), gold (Au), calcium (Ca), Titanium (Ti), Yttrium (Y), Sodium (Na), Ruthenium (Ru), Manganese (Mn), Indium (In), Magnesium (Mg), Lithium (Li), Ytterbium (Yb), Lithium fluoride (LiF) ) And the like. Further, magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / potassium (K), astatine (At) / oxidized astatine (AtO ₂ ), lithium (Li) / aluminum An alloy such as (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or lithium fluoride (LiF) / calcium (Ca) / aluminum (Al) may be used. Furthermore, tin oxide (SnO), zinc oxide (ZnO), or conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO) may be used.

  The first electrode 13 may be formed by stacking a plurality of layers made of the above materials. Examples of the material having a large work function include indium tin oxide (ITO) and indium zinc oxide (IZO). Further, in the case of the bottom emission method, it is preferably formed of a light transmissive material such as indium tin oxide (ITO). According to this configuration, the absorption rate of the light from the organic EL layer 17 by the first electrode 13 can be lowered, and high luminance can be realized. On the other hand, in the case of a top emission method in which light emission from the organic EL layer 17 is extracted from the film formation surface side, the first electrode 13 is preferably formed of a light reflective material such as aluminum (Al). According to this configuration, the light emitted from the organic EL layer 17 toward the anode side is reflected by the first electrode 13 toward the second electrode 14 (cathode) having translucency with high reflectance. Therefore, the light emission rate of light from the organic EL layer 17 can be increased, and high luminance can be realized.

  The organic EL layer 17 is formed on the first electrode 13, and a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer (all not shown) are stacked in this order. Has been configured. The organic EL layer 17 may be formed with a smaller area than the lower first electrode 13 or may be formed so as to cover the first electrode 13 with a larger area. In the embodiment of the present invention, the edge cover is not formed on the end portion of the first electrode 13, but no voltage is applied to the end portion of the first electrode 13, so that problems such as element destruction do not occur. .

  The hole injection layer is also referred to as an anode buffer layer, and brings the energy levels of the first electrode 13 (anode) and the organic EL layer 17 closer to improve the hole injection efficiency from the first electrode 13 to the organic EL layer 17. Used for. As the hole injection layer material, use of triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, phenylenediamine derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, etc. Can do.

  The hole transport layer has a function of improving the efficiency of transporting holes from the first electrode 13 to the organic EL layer 17. As the hole transport layer material, porphyrin derivatives, aromatic tertiary amine compounds, styrylamine derivatives, polyvinylcarbazole, poly-p-phenylenevinylene, polysilane, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives , Pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amine-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, hydrogenated amorphous silicon, hydrogenated amorphous silicon carbide, zinc sulfide, Alternatively, zinc selenide or the like can be used.

  The light emitting layer has a function of emitting light by recombining holes injected from the first electrode 13 (anode) and electrons injected from the second electrode 14 (cathode). As the light emitting layer material, metal oxinoid compound [8-hydroxyquinoline metal complex], naphthalene derivative, anthracene derivative, diphenylethylene derivative, vinylacetone derivative, triphenylamine derivative, butadiene derivative, coumarin derivative, benzoxazole derivative, oxadiazole Derivatives, oxazole derivatives, benzimidazole derivatives, thiadiazole derivatives, benzthiazole derivatives, styryl derivatives, styrylamine derivatives, bisstyrylbenzene derivatives, tristyrylbenzene derivatives, perylene derivatives, perinone derivatives, aminopyrene derivatives, pyridine derivatives, rhodamine derivatives, aquidin derivatives , Phenoxazone, quinacridone derivative, rubrene, poly-p-phenylene vinylene, or polysilane It is possible.

  The electron transport layer has a role of efficiently transferring electrons to the light emitting layer. Examples of the electron transport material include organic compounds such as oxadiazole derivatives, triazole derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, tetracyanoanthraquinodimethane derivatives, diphenoquinone derivatives, fluorenone derivatives, silole derivatives, metal oxinoid compounds, and the like. Can be used.

The electron injection layer is used to bring the energy levels of the second electrode 14 and the organic EL layer 17 closer to each other and to improve the efficiency with which electrons are injected from the second electrode 14 to the organic EL layer 17, thereby providing an organic EL element. The drive voltage of 12 can be lowered. The electron injection layer is also called a cathode buffer layer. As an electron injection material, inorganic alkali compounds such as lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), calcium fluoride (CaF ₂ ), strontium fluoride (SrF ₂ ), barium fluoride (BaF ₂ ), Al ₂ O ₃ and SrO can be used.

  The second electrode 14 has a smaller area than the first electrode 13 below. The second electrode 14 has a function of injecting electrons into the organic EL layer 17. More preferably, the second electrode 14 is made of a material having a small work function. This is because the efficiency of electron injection into the organic EL layer 17 can be improved by forming the second electrode 14 with a material having a small work function.

  As the constituent material of the second electrode 14, silver (Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni), tungsten (W), gold (Au), calcium (Ca), Titanium (Ti), Yttrium (Y), Sodium (Na), Ruthenium (Ru), Manganese (Mn), Indium (In), Magnesium (Mg), Lithium (Li), Ytterbium (Yb), Lithium fluoride (LiF) ) Etc. can be used. The second electrode 14 is made of magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / potassium (K), astatine (At) / oxidized astatine (AtO2), lithium (Li) / aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or lithium fluoride (LiF) / calcium (Ca) / aluminum (Al) alloy or the like Good. Furthermore, the second electrode 14 may be formed of a conductive oxide such as tin oxide (SnO), zinc oxide (ZnO), or indium tin oxide (ITO) or indium zinc oxide (IZO). The second electrode 14 can also be formed by laminating a plurality of layers made of these materials. Materials having a low work function include magnesium (Mg), lithium (Li), lithium fluoride (LiF), magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / Examples include potassium (K), lithium (Li) / aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or lithium fluoride (LiF) / calcium (Ca) / aluminum (Al). It is done. Further, when the organic EL element 12 is a top emission type in which light from the light emitting layer is extracted from the second electrode 14 side, the second electrode 14 is formed of a light transmissive material such as indium tin oxide (ITO). Preferably it is. According to this configuration, the absorption rate of the light from the light emitting layer by the second electrode 14 can be lowered, and high luminance can be realized. On the other hand, when the organic EL element 12 is a bottom emission method in which light from the light emitting layer is extracted from the substrate side, the second electrode 14 is preferably formed of a light reflective material such as aluminum (Al). According to this configuration, the light emitted from the light emitting layer toward the second electrode 14 is reflected by the second electrode 14 toward the first electrode 13 with a high reflectance. Therefore, the light emission rate of light from the light emitting layer can be increased, and high luminance can be realized.

The sealing film 18 is formed so as to cover the second electrode 14 in order to protect the second electrode 14 from moisture in the atmosphere. The sealing film 18 is, for example, any one of insulating films such as silicon oxide (SiO ₂ ), silicon nitride (Si _x N _y : X and Y are real numbers greater than 0), and silicon oxynitride (SiON). A single film containing a material or a laminated film containing two or more kinds of the materials can be used. In the sealing film 18, a contact hole 22 reaching the second electrode 14 is formed in each pixel region 15. One contact hole 22 may be formed in each pixel region 15 or a plurality of contact holes 22 may be formed.

  The conductive film 19 is electrically connected to the second electrode 14 through the contact hole 22 of the sealing film 18. The conductive film 19 is made of ITO or the like and is connected to a driving power source for the organic EL display element outside the display area of the display panel, although not shown.

  Next, the configuration of the pixel pattern partitioned by the source wiring and the gate wiring in the organic EL display device 10 will be described in detail. FIG. 3 is a plan view of a pixel pattern partitioned by the source wiring 30a (data line) and the gate wiring 31a (scanning line) of the organic EL display device 10, which is the most basic 2 TFT in driving the organic EL element. It is a pattern figure which concerns on a structure. 4 shows a cross-sectional view taken along line B-B ′ of FIG. 3.

  3 and 4, each of the plurality of source lines 30a formed in a stripe shape is electrically connected to the TFT 11a in the upper and lower pattern connection regions 33, and a data signal is input to the TFT 11a. The plurality of gate lines 31a extend in parallel to each other in a direction intersecting with the direction in which the source line 30a extends. Each of the plurality of gate wirings 31a is a gate of the TFT 11a, and a scanning signal is input to each of the TFTs 11a. The drain of the TFT 11a is connected to the gate wiring 31b. The gate wiring 31b is the gate of the TFT 11b. A portion where the source line 30b and the gate line 31b overlap forms a storage capacitor Cs. The source wiring 30a is connected to the source of the TFT 11b. The drain of the TFT 11 b is electrically connected to the first electrode 13. The TFT 11a supplies a charge to Cs based on signals input from the source wiring 30a and the gate wiring 31a, operates the TFT 11b, and supplies current to the first electrode 13 based on the input signal. The source wirings 30a and 30b and the gate wirings 31a and 31b are each formed of a conductive material such as titanium (Ti), aluminum (Al), tantalum (Ta), or tungsten (W).

  In FIG. 4, a base film 34 is formed on the insulating substrate 20 of the TFT substrate 16, and a gate insulating film 35 is formed on the base film 34. The gate insulating film 35 has a function of insulating the gate wirings 31 a and 31 b and the island-shaped semiconductor formed in the semiconductor region 36 and ensuring the pressure resistance of the TFT 11.

  The gate insulating film 35 can be formed of a silicon layer, a silicon nitride layer, a tantalum oxide layer, or the like, and has a multilayer structure such as a three-layer structure of a silicon oxide layer / a silicon nitride layer / a silicon oxide layer. It doesn't matter.

  An interlayer film 37 is formed on the gate insulating film 35 and has a function of insulating the gate electrode and the source electrode of the TFT 11. The interlayer film 37 can be composed of a silicon layer, a silicon nitride layer, a tantalum oxide layer, or the like, and has a multilayer structure such as a three-layer structure of silicon oxide layer / silicon nitride layer / silicon oxide layer. It doesn't matter.

  The island-shaped semiconductor of the TFT 11 can be formed of polysilicon (Si) or the like. The source electrode and drain electrode of the TFT 11 are made of aluminum or the like and are electrically connected to the first electrode 13.

  The planarizing film 21 is formed on the interlayer film 37 and has a function of flattening the TFT 11 formation film surface. With the planarization film 21, the first electrode 13, the organic EL layer 17, and the like formed on the planarization film 21 can be formed flat. The planarizing film 21 can be formed of a resin material such as acrylic, novolac, or polyimide.

  In this embodiment, the TFT 11 is used as the switching element, but an MIM (Metal-Insulator-Metal) diode or the like may be used instead of the TFT 11.

  In the present embodiment, the top gate TFT substrate 16 is shown, but a bottom gate structure may be used. The semiconductor formation region of the TFT 11 may include an oxide semiconductor such as amorphous silicon, microcrystalline silicon, polysilicon, or zinc oxide.

  As shown in FIGS. 3 and 4, the second electrode 14 of the organic EL element 12 is formed smaller than the first electrode 13. The contact hole 22 of the sealing film 18 is formed on the second electrode 14. The size of the contact hole 22 is not particularly limited as long as it is smaller than that of the second electrode 14. The shape of the contact hole 22 is not particularly limited. For example, as shown in FIG. 3, the contact hole 22 may be formed in a rectangular shape at one corner on the second electrode 14. Moreover, it may be formed in a large rectangular shape so as to occupy most of the second electrode 14 like a contact hole 22a shown in FIG. Furthermore, it may be formed in a rectangular shape at a plurality of locations on the second electrode 14 like a contact hole 22b shown in FIG. Further, like a contact hole 22c shown in FIG. 5C, it may be formed at two corners on the second electrode 14, or may be formed in a rectangular shape having moderate corners. Further, like a contact hole 22d shown in FIG. 5 (d), the contact hole 22d may be formed in a rectangular shape having a large and gentle corner so as to occupy most of the second electrode. Moreover, like the contact hole 22e shown in FIG.5 (e), you may form in the rectangular shape which has a moderate angle | corner in several places on the 2nd electrode 14. FIG.

  FIG. 6 shows an example of a drive circuit diagram of the organic EL display device 10, and FIG. 7 shows an example of a drive circuit conceptual diagram of the organic EL display device 10. In the pixel circuit as shown in FIG. 6, in addition to the driving circuit configuration of two TFTs, there are cases where three or more TFTs are used. However, the effect of the present invention can be achieved even when three or more TFTs are used. It is valid. As shown in FIG. 7, the organic EL display device 10 is composed of a scanning line driving circuit, a data line driving circuit, a power supply circuit, and the like around the display area in which a large number of pixel circuits as shown in FIG. 6 are arranged. ing. In the organic EL display device 10, the TFT of each pixel is operated based on the signal of the data line driving circuit or the scanning line driving circuit, whereby the TFT of each pixel is driven, and a current flows through the organic EL element 12. The organic EL element 12 emits light and an image is displayed.

(Method for manufacturing organic EL display device 10)
Next, a method for manufacturing the organic EL display device 10 according to Embodiment 1 of the present invention will be described.

  First, as shown in FIG. 8, a TFT substrate 16 is formed by a known method, and a through hole that leads to the drain region is formed in the planarizing film 21 or the like. Subsequently, a first electrode 13 made of ITO is formed on the TFT substrate 16 so as to be connected to the drain electrode of the TFT 11 through a through hole provided in the planarizing film 21.

  Next, as shown in FIG. 9, for example, a low molecular organic EL layer 17 is formed on the first electrode 13. As the low-molecular-type organic EL layer 17, first, a 30 nm-thickness hole injection layer / hole composed of NPP (N, N-di (naphthalene-1-yl) -N, N-diphenyl-benzidene) is used. A transport layer is formed, and then a light emitting layer is formed at 30 nm. Further, an electron transport layer / electron injection layer having a film thickness of 30 nm made of Alq3 (aluminato-tris-8-hydroxyquinolate) is formed.

  Subsequently, the second electrode 14 made of a magnesium silver alloy and having a film thickness of 5 nm is formed on the organic EL layer 17 by vapor deposition. At this time, the second electrode 14 is formed inside the end portion of the first electrode 13 using a mask by vapor deposition.

As a vapor deposition method using a mask, first, a material to be deposited as an evaporation source is set in a crucible in a vacuum chamber, and a predetermined thin film forming portion of the substrate is aligned with a vapor deposition mask opening, and the substrate is And the deposition mask is also set in the vacuum chamber. In this state, the crucible is heated to evaporate the film forming material and form a film on the substrate. Specifically, for example, a crucible of magnesium into pieces of a vacuum deposition apparatus, silver pieces in a crucible, and set the ITO powder in a crucible, also leave set an organic EL element forming substrate on a substrate holder, the atmosphere pressure is 10 ^- Vacuum is applied until ⁴ Pa is reached. A shutter is installed between the crucible and the substrate and is initially closed. A vapor deposition mask is provided between the shutter and the substrate. The vapor deposition mask is installed close to the substrate. The vapor deposition mask has an opening formed in a portion corresponding to a film formation portion of the substrate, and the film forming material is formed on the substrate through the opening. The opening of the vapor deposition mask is formed for each second electrode formation portion of the pixel. The opening of the vapor deposition mask and the second electrode forming part are aligned in advance. Thereafter, the crucible of the magnesium piece and the silver piece is heated, and the magnesium film and the silver film are formed to a thickness of 1 to 20 nm by opening and closing the shutter for a short time. Next, only the crucible made of ITO powder is heated, and the ITO film is formed to a thickness of 100 nm by opening and closing the shutter for a certain period of time.

Next, as shown in FIG. 10, a sealing film 18 made of silicon oxide (SiO ₂ ) having a thickness of 500 nm is formed by a sputtering apparatus in a region including at least the display region of the substrate. For forming the sealing film 18, first, a substrate is set in the chamber, argon (Ar) gas is supplied at 190 sccm, oxygen (O ₂ ) gas is supplied at 10 sccm, the atmospheric gas pressure is set at 0.3 Pa, and the SiO ₂ target is set. Use and deposit at 0.2 kW for 30 minutes. Subsequently, a SiO ₂ layer is formed as the sealing film 18 in a film thickness of 500 nm by forming the film at a power of 2 kW for 2 hours.

Next, a SiO ₂ film is patterned using photolithography technology. The patterning of the SiO ₂ film, a positive type photoresist such as a SiO ₂ film on the photoresist such as the commercially available OFPR-800 (manufactured by Tokyo Ohka Kogyo) was applied to the entire surface by a spin method, using a photomask The contact hole 22 in the region of the second electrode 14 is exposed and developed by immersing it in a 2.38% tetramethylammonium hydroxide (TMAH) alkaline developer. Thereby, a resist pattern 40 in which the contact holes 22 are opened is formed.

Subsequently, the substrate on which the resist pattern 40 is formed is dry etched. The dry etching of the substrate is performed using carbon tetrafluoride (CF ₄ ) as an etching gas with a dry etching apparatus under conditions of a flow rate of 300 sccm, an atmospheric pressure of 30 Pa, and an input power of 2 kW. At this time, the contact hole 22 is formed, but the etching is stopped at the ITO film portion, so that the organic EL layer 17 is not etched.

  Next, the resist pattern 40 is removed by an ashing device under the conditions of an oxygen gas flow rate of 300 sccm, an atmospheric pressure of 30 Pa, and an input power of 2 kW. Since the organic EL layer 17 is completely covered with the ITO film or the sealing film 18, the organic EL layer 17 is not directly exposed to a resist, a developer, an etching gas, or the like, and the organic EL layer 17 is not damaged.

  Next, an ITO film is formed as a conductive film 19 in a region including the display area by a vacuum deposition method or a sputtering method, and then the organic EL element 12 forming substrate is sealed with a sealing resin in a nitrogen gas atmosphere with an oxygen concentration of 100 ppm or less. By sealing with sealing glass, the organic EL display device 10 shown in FIG. 4 is completed. The conductive film 19 is formed at a connection portion between the display area and a power supply circuit (Vcom) provided outside the display area.

  Further, mask vapor deposition is performed when the organic EL layer 17 is formed. As shown in FIG. 11, the alignment between the substrate and the vapor deposition mask at that time shifts, so that the inside of the first electrode 13 and the first electrode 13 are formed. In some cases, the organic EL layer 17 ′ is formed at a position protruding from the top. In the embodiment of the present invention, since the second electrode 14 is formed on the inner side of the first electrode 13, no voltage is applied to a portion of the organic EL layer 17 ′ that extends beyond the predetermined pixel formation region. For this reason, a problem such as a short circuit does not occur at the pattern edge portion of the first electrode 13, and the display performance of the organic EL display device 10 is not affected.

  As shown in FIG. 11, when the organic EL layer 17 ′ is formed on the inner side of the first electrode 13, the second electrode 14 is formed by forming the second electrode 14 on the inner side with a margin for the width. And the first electrode 13 can be prevented from being short-circuited. Moreover, the vapor deposition mask margin of the organic EL element 12 can be expanded by forming the second electrode 14 inside the first electrode 13.

(Effect of Embodiment 1)
Next, the effect of Embodiment 1 of this invention is demonstrated.

  The organic EL display device 10 is formed so that the area of the second electrode 14 is smaller than that of the lower first electrode 13 and covers the second electrode 14, and a contact hole 22 reaching the second electrode 14 is formed. And a conductive film 19 formed on the sealing film 18 and electrically connected to the second electrode 14 through the contact hole 22. For this reason, even if an edge cover is not formed, current does not flow to the end portion of the first electrode 13, and deterioration in display quality of the organic EL display device 10 can be suppressed. Further, since no edge cover is formed, it is possible to improve throughput and reduce costs during production.

  In the organic EL display device 10, a plurality of pixel regions 15 arranged in a matrix are defined by the first electrode 13 and the second electrode 14, and the contact hole 22 of the sealing film 18 is formed in each pixel region 15. A plurality are formed inside. For this reason, in each pixel region 15, the second electrode 14 and the conductive film 19 can be made to conduct more favorably.

  Further, the organic EL display device 10 is provided with a TFT substrate 16 below the first electrode 13. According to such a configuration, it is easy to divert the TFT substrate 16 produced for the liquid crystal display device to the organic EL display device 10 that does not need to form an edge cover at the end of the first electrode 13. Become. For this reason, the manufacturing cost at the time of mass production of an apparatus becomes favorable.

(Embodiment 2)
Next, an organic EL display device 50 according to Embodiment 2 of the present invention will be described.

(Configuration of the organic EL display device 50)
FIG. 12 is a cross-sectional view of the organic EL display device 50. The organic EL display device 50 is different from the organic EL display device 10 of Embodiment 1 in that the organic EL layer 52 includes a coffee stain portion 51. In general, when forming an organic EL element by a wet coating method such as an ink jet method, the coffee stain portion is generated at the periphery of the pattern of a predetermined element formation portion after ink formed by dissolving a predetermined organic material in a solvent evaporates. is there. Hereinafter, in the organic EL display device 50, the same components as those of the organic EL display device 10 of Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The organic EL display device 50 includes a TFT substrate 16 and an organic EL element 55. The organic EL element 55 includes a plurality of first electrodes 13 provided in a predetermined arrangement on the TFT substrate 16, an organic EL layer 52 formed on each of the plurality of first electrodes 13, and the organic EL layer 52 A second electrode 14 formed on the sealing film 18, a sealing film 18 formed so as to cover the second electrode 14, and a conductive film 19 formed on the sealing film 18. It is sealed with a sealing resin and a sealing glass (each not shown) in a gas atmosphere.

  The organic EL layer 52 includes a hole transport layer 53 and a light emitting layer 54 and includes a coffee stain portion 51. The inside of the coffee stain portion 51 has a depressed shape, and the second electrode 14 having a smaller area than the first electrode 13 is formed in the portion.

(Method for manufacturing organic EL display device 50)
Next, a method for manufacturing the organic EL display device 50 according to Embodiment 2 will be described.

First, as shown in FIG. 13, the TFT substrate 16 is formed in the same manner as in the first embodiment. Subsequently, the TFT substrate 16 is surface-treated so that the first electrode 13 is lyophilic and the planarization film 21 is lyophobic. Specifically, after the TFT substrate 16 is set in a vacuum chamber and evacuated for a predetermined time, CF ₄ is flowed at 200 sccm and O ₂ is flowed at 10 sccm, the atmospheric gas pressure is set to 5 Pa, and the process is performed at a power of 100 W for 2 minutes. To do. As a result, the ITO film as the first electrode 13 is lyophilic (the ink material is easy to spread), and the flattening film 21 is liquid repellent (the ink material is difficult to spread).

  Next, the hole transport layer 53 is formed on the first electrode 13 by using a wet coating method such as an inkjet method. That is, first, an ink 58 is prepared by dissolving (or dispersing) a hole transport material in a solvent, and the ink 58 is applied to each region of the first electrode 13 partitioned by the planarizing film 21 subjected to the liquid repellent treatment. Dripping. Thereafter, the dropped ink 58 is dried to form the hole transport layer 53 having a film thickness of 50 to 150 nm including the coffee stain portion 51 as shown in FIG. For drying, it is preferable to heat at 150 to 250 ° C. for 0.5 to 120 minutes using a hot plate or oven.

  Hole transport materials for forming the hole transport layer 53 are porphyrin derivatives, aromatic tertiary amine compounds, styrylamine derivatives, polyvinylcarbazole, poly-p-phenylene vinylene, polysilane, triazole derivatives, oxadiazole derivatives. , Imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amine-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, hydrogenated amorphous silicon, hydrogen Amorphous silicon carbide, zinc sulfide, or zinc selenide.

  As a solvent for dissolving (or dispersing) the hole transport material, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, hemimeritene [1,2,3-trimethylbenzene], pseudocumene [1,2 , 4-trimethylbenzene], mesitylene [1,3,5-trimethylbenzene], cumene [isopropylbenzene], planarite [1,2,3,4-tetramethylbenzene], isodurene [1,2,3,5- Tetramethylbenzene], durene [1,2,4,5-tetramethylbenzene], p-cymene [isopropyltoluene], tetralin [1,2,3,4-tetrahydronaphthalene], cyclohexylbenzene, melitene [hexamethylbenzene] ], Methanol, ethanol, 1-propanol, 2-propanol [ PA; isopropyl alcohol], ethylene glycol [1,2-ethanediol], diethylene glycol, 2-methoxyethanol [ethylene glycol monomethyl ether, methyl cellosolve], 2-ethoxyethanol [ethylene glycol monoethyl ether, cellosolve], 2- ( Methoxymethoxy) ethanol, 2-isopropoxyethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, glycerin, acetone, N-methyl-2-pyrrolidone, 1,3 -Dimethyl-2-imidazolidinone, anisole [methoxybenzene], water, etc. are mentioned. Moreover, you may mix and use these solvents.

  Next, the light emitting layer 54 is formed on the hole transport layer 53. As a formation method of the light emitting layer 54, the inkjet method etc. are mentioned similarly to the formation method of the positive hole transport layer 53. FIG. As shown in FIG. 15, a film containing a light emitting material is formed by dropping an ink 59 by an ink jet method, and then dried to have a film thickness of 50 to 150 nm including a coffee stain portion 51 as shown in FIG. 16. The light emitting layer 54 is formed. For drying, it is preferable to heat at 150 to 250 ° C. for 0.5 to 120 minutes using a hot plate or oven. The solvent that can be used for the ink 59 for forming the light emitting layer 54 is the same as the solvent that can be used for forming the hole transport layer 53 described above. The light emitting layer 54 has a function of emitting light by recombining holes injected from the first electrode 13 and electrons injected from the second electrode 14. Examples of the light emitting material for forming the light emitting layer 54 include metal oxinoid compounds [8-hydroxyquinoline metal complexes], naphthalene derivatives, anthracene derivatives, diphenylethylene derivatives, vinylacetone derivatives, triphenylamine derivatives, butadiene derivatives, coumarin derivatives, Benzoxazole derivatives, oxadiazole derivatives, oxazole derivatives, benzimidazole derivatives, thiadiazole derivatives, benzthiazole derivatives, styryl derivatives, styrylamine derivatives, bisstyrylbenzene derivatives, tristyrylbenzene derivatives, perylene derivatives, perinone derivatives, aminopyrene derivatives, pyridine Derivatives, rhodamine derivatives, acuidine derivatives, phenoxazone, quinacridone derivatives, rubrene, poly-p-phenylene vinylene, Is, polysilane, and the like.

  Next, in the same manner as in the first embodiment, Mg / Ag is formed to a thickness of 1 to 20 nm using a vapor deposition mask, and ITO is formed in the same manner to form the second electrode 14. Subsequently, after forming the sealing film 18 and the conductive film 19 in the same manner as in the first embodiment, the organic EL element 12 formation substrate is sealed with the sealing resin and the sealing glass in a nitrogen gas atmosphere with an oxygen concentration of 100 ppm or less. The organic EL display device 50 is completed by sealing with.

(Effect of Embodiment 2)
In the second embodiment of the present invention, a surface treatment is applied to the TFT substrate 16 that has not completed forming the bank at the pattern edge portion of the first electrode 13 and the ITO process of the first electrode 13 is completed, and the upper surface of the first electrode 13 is controlled. The liquidity and the flattening film 21 are made liquid repellent. Thereafter, the organic EL layer 52 including the coffee stain portion 51 is formed by a wet coating method such as an inkjet method.

  According to such a configuration, it is possible to form the organic EL element 55 in a wet coating formation method such as an inkjet method without forming a bank (partition wall) that holds the ink in the pixel. Further, normally, the thickness of the coffee stain portion 51 becomes thick and unevenness of the film thickness of the organic EL element 55 occurs. However, according to the present embodiment, no voltage is applied to the coffee stain portion 51 and almost no current is generated. Since it does not flow, the deterioration of the organic EL element characteristics is satisfactorily suppressed.

  The organic EL element 55 is formed of a very thin thin film having a thickness of the organic EL layer 52 of about 100 to 500 nm. For this reason, the uniform film thickness of the organic EL layer 52 is an important issue for ensuring its performance, but in the present embodiment, the second electrode 14 is formed inside the coffee stain portion 51. Thus, the uniform organic EL layer 52 is formed under the second electrode 14 defining the pixel. For this reason, the film thickness of the organic EL layer 52 sandwiched between the second electrode 14 and the first electrode 13 becomes uniform, and it becomes possible to form a highly reliable organic EL element 55 with little display unevenness. .

  As described above, the present invention is useful for an organic EL display device and a manufacturing method thereof.

1 is a plan view of an organic EL display device according to Embodiment 1. FIG. FIG. 2 is a cross-sectional view taken along line A-A ′ in FIG. 1. It is a top view of the pixel pattern divided by the source wiring and gate wiring of an organic electroluminescence display. FIG. 4 is a sectional view taken along line B-B ′ in FIG. 3. It is a figure which shows the other form of a contact hole. It is an example of the drive circuit diagram of an organic electroluminescence display. It is a drive circuit conceptual diagram of an organic EL display device. FIG. 3 is a cross-sectional view of the organic EL display device after forming a first electrode in the manufacturing process of Embodiment 1. 4 is a cross-sectional view of the organic EL display device after forming a second electrode in the manufacturing process of Embodiment 1. FIG. 3 is a cross-sectional view of the organic EL display device after forming a resist film in the manufacturing process of Embodiment 1. FIG. It is sectional drawing of the organic electroluminescent display device in which the organic electroluminescent layer protruded and protruded from the 1st electrode. 6 is a cross-sectional view of an organic EL display device according to Embodiment 2. FIG. 6 is a cross-sectional view of an organic EL display device after dropping a hole transport material in the manufacturing process of Embodiment 2. FIG. 6 is a cross-sectional view of an organic EL display device after formation of a hole transport layer in the manufacturing process of Embodiment 2. FIG. 6 is a cross-sectional view of an organic EL display device after a light emitting material is dropped in the manufacturing process of Embodiment 2. FIG. 6 is a cross-sectional view of an organic EL display device after formation of a light emitting layer in the manufacturing process of Embodiment 2. FIG.

Explanation of symbols

10, 50 Organic EL display device
11, 11a, 11b TFT
12,55 Organic EL device
13 First electrode
14 Second electrode
15 pixel area
16 TFT substrate
17, 17 ', 52 Organic EL layer
18 Sealing film
19 Conductive film
20 Insulating substrate
22, 22a-22e Contact hole
51 Coffee stain
58,59 ink

Claims (6)

A first electrode;
An organic EL layer formed on the first electrode;
A second electrode formed on the organic EL layer and having a smaller area than the first electrode below;
A sealing film provided so as to cover the second electrode and having a contact hole reaching the second electrode;
A conductive film formed on the sealing film and electrically connected to the second electrode through the contact hole;
An organic EL display device. The organic EL display device according to claim 1,
A plurality of pixel regions arranged in a matrix with the first electrode and the second electrode are defined,
An organic EL display device in which a plurality of contact holes of the sealing film are formed in each pixel region. The organic EL display device according to claim 1,
Below the first electrode, an organic EL provided with a switching element substrate comprising an insulating substrate and a switching element formed on the insulating substrate and electrically connected to the first electrode. Display device. The organic EL display device according to claim 1,
The organic EL layer is an organic EL display device having a coffee stain portion. A first step of preparing a first electrode;
A second step of forming an organic EL layer on the first electrode;
Forming a second electrode having a smaller area than the first electrode on the organic EL layer;
A fourth step of forming a sealing film so as to cover the second electrode;
A fifth step of forming a contact hole reaching the second electrode in the sealing film;
A sixth step of forming a conductive film electrically connected to the second electrode through the contact hole on the sealing film;
A method for manufacturing an organic EL display device comprising: In the manufacturing method of the organic electroluminescent display device described in Claim 5,
In the second step, an organic EL display device manufacturing method in which an organic EL layer having a coffee stain portion is formed on the first electrode using a wet coating method.

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