JP5292863B2 - Organic electroluminescent display device and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent display device capable of efficiently performing hole injection by using an inorganic compound having a composition ratio gradient in the film thickness direction of a hole transport layer, capable of simplifying a process and having highly efficient performance, and to provide a manufacturing method thereof. <P>SOLUTION: The organic electroluminescent display device includes: a substrate; a first electrode formed on the substrate; an organic electroluminescent layer having a plurality of layers including a hole transport layer, which is an inorganic compound formed on the first electrode, and an organic light-emitting layer; and a second electrode formed on the organic light-emitting medium layer. The hole transport layer has the composition ratio gradient in the film thickness direction. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an organic light emitting display device and a method for manufacturing the same, and in particular, by using an inorganic compound having a composition ratio gradient in a film thickness direction as a hole transport layer, an organic electric field capable of obtaining highly efficient characteristics. The present invention relates to a light emitting display device and a manufacturing method thereof.

  An organic electroluminescent element (hereinafter referred to as an “organic EL element”) is an element in which an organic light emitting layer made of an organic light emitting material is formed between two opposing electrodes, and the organic light emitting layer emits light by passing a current. However, it is important to control the thickness of the organic light emitting layer in order to produce an efficient and reliable device. Moreover, in order to manufacture a color display using an organic EL element, it is necessary to pattern with high definition.

  Organic light-emitting materials forming the organic light-emitting layer include low-molecular materials and polymer materials. In general, a low molecular material is formed into a thin film by a dry coating method such as a vacuum deposition method, and 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, recently, a method in which a polymer material is dissolved in a solvent to form a coating solution and a thin film is formed by a wet coating method has been tried. In the case of forming an organic light emitting medium layer including an organic light emitting layer by a wet coating method using a coating material of a polymer material, the layer structure is generally a two-layer structure in which a hole transport layer and an organic light emitting layer are laminated from the anode side. Is. On the other hand, the layer structure of the low molecular weight material is generally composed of three layers laminated from the anode side to the hole transport layer, the organic light emitting layer, and the electron transport layer, or four layers or more laminated the injection layer between each transport layer and the electrode. Is. As these attempts, Patent Document 1 discloses an example of a polymer material in which a coating type hole transport layer is formed, and Patent Document 2 discloses an example of a low molecular material in which an electron transport layer is formed. Has been.

The reason why the layer structure is multi-layered is that holes and electrons are efficiently injected into the organic light emitting layer by separating the functions of the respective layers, so that the organic light emitting layer emits light efficiently. For example, the work function is used as one of selection criteria for the hole transport material. By designing the layer structure so that the work function sequentially increases from the work function of the anode to the work function of the organic light emitting layer for each layer, the barrier can be reduced and hole injection can be performed efficiently. In the case of a low molecular material, there is no limit on the upper limit of stacking, but it is necessary to prepare a vacuum chamber for each material, resulting in an increase in equipment. In the case of a polymer material, since the lower layer is eroded by the coating solution for forming the upper layer, stacking becomes difficult.
Japanese Patent No. 2916098 Japanese Patent No. 3556252

  The present invention can efficiently inject holes by using an inorganic compound having a composition ratio gradient with respect to the film thickness direction of the hole transport layer, simplifying the process and highly efficient organic electroluminescence. A display device and a manufacturing method thereof are provided.

The invention according to claim 1 of the present invention includes a substrate, a first electrode formed on the substrate, a hole transport layer having a transition metal and its oxide formed on the first electrode, and a hole transport. An organic light emitting medium layer having a plurality of layers including an organic light emitting layer formed on the layer, and a second electrode formed on the organic light emitting medium layer, wherein the hole transport layer is in the film thickness direction. The first electrode side is a transition metal, the organic light emitting layer side is an oxide of a transition metal, and the hole transport layer has a work function from the first electrode side to the organic light emitting layer side. The organic electroluminescent display device is characterized in that it becomes high .

The invention according to claim 2 of the present invention provides a substrate, forms a first electrode on the substrate, has a transition metal and its oxide on the first electrode, and has a composition ratio gradient with respect to the film thickness direction. Forming an organic light emitting medium layer having a plurality of layers including a hole transport layer having an organic light emitting layer formed on the hole transport layer, forming a second electrode on the organic light emitting medium layer, and forming holes; Forming the transport layer includes forming a transition metal with an inert gas at the start of film formation, and introducing a reactive gas over time to form an oxide of the transition metal. The organic electroluminescent display device manufacturing method is characterized in that the work function increases from the first electrode side to the organic light emitting layer side .

The invention according to claim 3 of the present invention is the method of manufacturing an organic light emitting display device according to claim 2 , wherein the hole transport layer is formed by physical vapor deposition. .

  According to the present invention, by using an inorganic compound having a composition ratio gradient with respect to the film thickness direction of the hole transport layer, hole injection can be efficiently performed, process simplification and high efficiency organic An electroluminescent display device and a method for manufacturing the same can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings referred to in the following description of the embodiments are for explaining the configuration of the present invention, and the size, thickness, dimensions, and the like of each part illustrated are different from the actual ones. The present invention is not limited to these.

  As shown in FIG. 1, an organic light emitting display 100 according to an embodiment of the present invention includes a substrate 101, a pixel electrode 102 provided for each pixel formed on the substrate 101, and a pixel electrode 102. A partition wall 103 formed for partitioning, a hole transport layer 104 formed above the pixel electrode 102, an interlayer layer 105 formed on the hole transport layer 104, and formed on the interlayer layer 105 The organic light emitting layer 106, the counter electrode 107 formed so as to cover the entire surface of the organic light emitting layer 106, the pixel electrode 102, the partition wall 103, the organic light emitting medium layer 110, and the counter electrode 107 so as to cover the counter electrode 107. And a sealing material 108 bonded by a sealing resin 109. Here, the hole transport layer 104, the interlayer layer 105, and the organic light emitting layer 106 are referred to as an organic light emitting medium layer 110. The sealing resin 109 and the sealing material 108 are referred to as a sealing body 111.

  The organic light emitting display device 100 is supported by a substrate 101. Any material can be used as the substrate 101 as long as the substrate 101 has mechanical strength and insulation and is excellent in dimensional stability.

  Examples of the material of the substrate 101 include plastic films and sheets such as glass, quartz, polypropylene, polyethersulfone, polycarbonate, cycloolefin polymer, polyarylate, polyamide, polymethyl methacrylate, polyethylene terephthalate, and polyethylene naphthalate, or these Metal oxides such as silicon oxide and aluminum oxide on plastic films and sheets, metal fluorides such as aluminum fluoride and magnesium fluoride, metal nitrides such as silicon nitride and aluminum nitride, metal oxynitrides such as silicon oxynitride , Translucent substrates with single or laminated polymer resin films such as acrylic resin, epoxy resin, silicone resin, polyester resin, metal foils such as aluminum and stainless steel, sheets, plates, plastic films Aluminum sheet, copper, nickel, a metal film such as stainless steel or the like can be used non-translucent substrate as a laminate but are not limited to these.

  What is necessary is just to select the translucency of the board | substrate 101 according to which surface light extraction of the organic electroluminescent display apparatus 100 is performed from. The substrate 101 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 light-emitting display device 100. It is preferable. In particular, in order to avoid the intrusion of moisture into the organic light emitting medium layer 110, it is preferable to reduce the moisture content and gas permeability coefficient in the substrate 101.

  The pixel electrode 102, which is the first electrode according to the embodiment of the present invention, is formed on the substrate 101 and patterned as necessary. The pixel electrode 102 is partitioned by a partition wall 103 and becomes a pixel electrode 102 corresponding to each pixel.

  Examples of the material of the pixel 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, these metal oxides, Either a single layer or a laminate of fine particle dispersion films in which fine particles of a metal material are dispersed in an epoxy resin or an acrylic resin can be used, but the present invention is not limited to these.

  When the pixel 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 (substrate 101 side), it is necessary to select a light-transmitting material. If necessary, in order to reduce the wiring resistance of the pixel electrode 102, a metal material such as copper or aluminum may be provided as an auxiliary electrode. Here, in the case of a so-called top emission structure in which light is extracted from above (a direction opposite to the substrate 101 side), the counter electrode 107 can be stacked on the substrate 101.

  As a formation method of the pixel electrode 102, depending on the material, dry film formation methods such as resistance heating evaporation method, electron beam evaporation method, reactive evaporation method, ion plating method, sputtering method, gravure printing method, screen printing A wet film forming method such as a method can be used, but the present invention is not limited thereto.

  As a patterning method of the pixel electrode 102, a patterning method such as a mask vapor deposition method, a photolithography method, a wet etching method, or a dry etching method can be used depending on a material and a film forming method.

  The partition wall 103 according to the embodiment of the present invention can be formed so as to partition a light emitting region corresponding to each pixel. As shown in FIG. 1, it is preferable to form the pixel electrode 102 so as to cover the end portion. In general, the active matrix driving type organic light emitting display device 100 has a pixel electrode 102 formed for each pixel, and each pixel tries to occupy as large an area as possible. The most preferable shape of the partition wall 103 formed in the above is basically a lattice shape that divides the pixel electrodes 102 by the shortest distance.

  As a method for forming the partition wall 103, an inorganic film is formed on the entire surface of the substrate (the substrate 1 and the pixel electrode 102), masked with a resist, and then dry-etched, or a photosensitive resin is laminated on the substrate, Although the method of setting it as a predetermined pattern by the photolithographic method is mentioned, in this invention, it is not necessarily limited to these. If necessary, a water repellent can be added to the resist and the photosensitive resin, or plasma or UV can be irradiated to impart liquid repellency to the ink after formation.

  A preferable height of the partition wall 103 is 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 2.0 μm or less. If the height of the partition wall 103 is higher than 10 μm, the formation and sealing of the counter electrode 107 is hindered. If the height of the partition wall 103 is lower than 0.1 μm, the end of the pixel electrode 102 cannot be covered, or an organic light emitting medium When the layer 110 is formed, the adjacent pixels are short-circuited or mixed in color.

  The organic light emitting medium layer 110 according to the embodiment of the present invention includes a hole transport layer 104, an interlayer layer 105, and an organic light emitting layer 106. In addition to the hole transport layer 104 and the interlayer layer 105, layers such as a hole injection layer, an electron transport layer, and an electron injection layer can be suitably used as the functional layer of the organic light emitting medium layer 110.

After the partition wall 103 is formed, the hole transport layer 104 can be formed. In the case where an inorganic compound is used as the hole transport material of the hole transport layer 104 according to the embodiment of the present invention, Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeOx (x to 0.1) are used as the inorganic compound. ), Transition metals such as NiO, CoO, Pr ₂ O ₃ , Ag ₂ O, MoO ₂ , ZnO, TiO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ , MnO ₂ An oxide can be used.

  As a method for forming the hole transport layer 104, a resistance vapor deposition method such as a physical vapor deposition (PVD method), an electron beam deposition method, an ion plating method, a sputtering method, or the like is used depending on the material. And can be suitably formed by introducing a reactive gas or a reactive ion during the film formation of the method. As the introduction method, for example, in the case of sputtering, the gas is mixed and introduced into the chamber at the same time so that the reactive gas pipe is connected to the inert gas pipe at the time of sputtering, or separately into the chamber by separate pipes. Make an introduction. In the case of the resistance heating vapor deposition method, there is a method in which an ion beam gun is installed in a chamber and a reactive gas is introduced as reactive ions with the ion beam gun, but the present invention is not limited to these. Hereinafter, in the description, both the inert gas and the reactive gas or reactive ion are shown as one type, but two or more types can be suitably used.

  As shown in FIG. 2, it is a graph of the introduction ratio of the inert gas and the reactive gas when the sputtering method according to the embodiment of the present invention is taken as an example. When the work function of a single metal is close to the work function of the pixel electrode 102 and the work function of the oxide is close to the work function of the interlayer layer 105, a metal film is formed with an inert gas at the start of film formation. By introducing the reactive gas, it is easy to inject carriers from the interface of the pixel electrode 102 and the transport to the interlayer layer 105 can be efficiently performed. In the case of extracting light from the pixel electrode 102 side, the thickness of the metal film and the oxide film may be changed according to the required transmittance, and the oxidation function may be changed according to the work function of the material of the hole transport layer 104. The pixel electrode 102 side can be suitably used as the metal oxide by changing the direction. Further, it is possible to save the cost due to multilayering of the hole injection layer and the hole transport layer 104 and the cost for providing a separate oxidation chamber and oxidizing it in a separate process.

  After the hole transport layer 104 is formed, the interlayer layer 105 can be formed. Examples of the material used for the interlayer 105 according to the embodiment of the present invention include polyvinyl carbazole or a derivative thereof, a polyarylene derivative having an aromatic amine in a side chain or a main chain, an arylamine derivative, a triphenyldiamine derivative, and the like. Examples thereof include polymers containing a group amine, but the present invention is not limited thereto. These materials are dissolved or dispersed in a solvent, and are formed using various coating methods using a spin coater or the like and letterpress printing methods. In the case where an inorganic material is used as the material of the interlayer layer 105, the metal oxide can be formed using a vacuum evaporation method, a sputtering method, or a CVD (Chemical Vapor Deposition) method. As the inorganic material of the interlayer layer 105, an inorganic compound containing at least one kind of transition element and typical element can be used.

  After the formation of the interlayer layer 105, the organic light emitting layer 106 can be formed. The organic light emitting layer 106 according to the embodiment of the present invention is a layer that emits light when a current is passed. Examples of the organic light-emitting material forming the organic light-emitting layer 106 include coumarin-based, perylene-based, pyran-based, anthrone-based, porphyrin-based, quinacridone-based, N, N′-dialkyl-substituted quinacridone-based, naphthalimide-based, N, N′-. Diaryl-substituted pyrrolopyrrole, iridium complex, and other luminescent dyes dispersed in polymers such as polystyrene, polymethylmethacrylate, and polyvinylcarbazole, and polyarylene, polyarylene vinylene, and polyfluorene polymers Examples of the material include, but are not limited to, the present invention.

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

  In FIG. 3, a printing substrate 302 having a pixel electrode 102, a partition wall 103, a hole transport layer 104, and an interlayer layer 105 is disposed on a stage 301, and organic light emission made of an organic light emitting material is formed on the printing substrate 302. The schematic of the relief printing apparatus 300 at the time of carrying out pattern printing of ink is shown. The relief printing apparatus 300 according to the embodiment of the present invention includes an ink tank 303, an ink chamber 304, an anilox roll 305, a plate copper 308 on which a plate 307 provided with a relief plate is mounted, and a doctor 306. doing. The ink tank 303 contains organic luminescent ink diluted with a solvent, and the organic luminescent ink is fed into the ink chamber 304 from the ink tank 303. The anilox roll 305 is instructed to rotate in contact with the ink supply unit of the ink chamber 304.

  As the anilox roll 305 rotates, the ink layer 309 of the organic light emitting ink supplied to the surface of the anilox roll 305 is formed with a uniform film thickness by the doctor 306. The ink of the ink layer 309 is transferred to the convex portion of the relief plate 307 mounted on the plate cylinder 308 that is driven to rotate in the vicinity of the anilox roll 305. The stage 301 is provided with a printing substrate 302 on which the pixel electrode 102, the hole transport layer 104, and the interlayer layer 105 are formed. The ink on the convex portion of the plate 307 is printed on the printing substrate 302. Then, if necessary, the organic light emitting medium layer 110 is formed on the substrate to be printed 302 through a drying process.

  The counter electrode 107 which is the second electrode according to the embodiment of the present invention can be formed. When the counter electrode 107 is used as a cathode, a substance having a high electron injection efficiency into the organic light emitting medium layer 110 and a low work function can be used.

  As a specific material of the counter electrode 107, a single metal such as Mg, Al, Yb is used, or a compound such as Li, Li oxide, LiF or the like is sandwiched about 1 nm at the interface in contact with the organic light emitting medium layer 110. Al or Cu having high conductivity may be laminated and used. Alternatively, in order to achieve both electron injection efficiency and stability, one or more metals such as Li, Mg, Ca, Sr, La, Ce, Er, Eu, Sc, Y, and Yb having a low work function and stable Ag, An alloy system with a metal element such as Al or Cu may be used. Specifically, alloys such as MgAg, AlLi, and CuLi can be used.

  The method of forming the counter electrode 107 can be 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, but is not limited to these in the present invention. is not.

  The organic light emitting display device 100 can emit light by sandwiching a light emitting material between electrodes (between the pixel electrode 102 and the counter electrode 107) and passing an electric current. In general, a sealing body 111 for shielding from the outside can be provided. The sealing body 111 can be manufactured, for example, by providing a sealing resin 109 on a sealing material 108. In FIG. 1, the sealing resin 109 is formed at the end of the sealing material 108, but the sealing resin 109 can be formed on the entire surface of one side of the sealing material 108 as needed.

The sealing material 108 needs to be a base material having low moisture and oxygen permeability. Examples of the material of the sealing material 108 include ceramics such as alumina (aluminum oxide), silicon nitride, and boron nitride, glass such as alkali-free glass and alkali glass, quartz, and moisture-resistant film. The invention is not limited to these. Examples of moisture-resistant films include films formed by CVD of SiOx on both sides of plastic substrates, films with low permeability and water-absorbing films, or polymer films coated with a water-absorbing agent. The water vapor transmission rate is preferably 10 ⁻⁶ g / m ² / day or less.

  As an example of the material of the sealing resin 109, a photocurable adhesive resin, a thermosetting adhesive resin, a two-component curable adhesive resin made of epoxy resin, acrylic resin, silicone resin, or the like, or ethylene ethyl acrylate ( EEA) Acrylic resins such as polymers, vinyl resins such as ethylene vinyl acetate (EVA), thermoplastic resins such as polyamide and synthetic rubber, and thermoplastic adhesive resins such as acid-modified products of polyethylene and polypropylene. it can.

  As an example of a method for forming the sealing resin 109 on the sealing material 108, a solvent solution method, an extrusion lamination method, a melting / hot melt method, a calendar method, a nozzle coating method, a screen printing method, a vacuum laminating method, a hot roll laminating. However, the present invention is not limited to these. A material having a hygroscopic property or an oxygen absorbing property may be contained as necessary. The thickness of the resin layer formed on the sealing material 108 is arbitrarily determined depending on the size and shape of the organic electroluminescent display device 100 to be sealed, but is preferably about 5 μm to 500 μm. Although the sealing resin 109 is formed on the sealing material 108 here, it can be formed directly on the organic electroluminescent display device 100 side.

  Finally, the organic electroluminescent display device 100 and the sealing body 111 are bonded together in a sealing chamber. In the case where the sealing body 111 has a two-layer structure of the sealing material 108 and the sealing resin 109 and a thermoplastic resin is used as the sealing resin 109, it is preferable to perform only pressure bonding with a heated roll.

  In the case where a thermosetting adhesive resin is used for the sealing resin 109, 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.

  An active matrix substrate 101 provided with a pixel electrode 102 provided on the substrate 101 was used. The size of the substrate 101 is 5 inches (127 mm) diagonal, and the number of pixels is 320 × 240.

  A partition wall 103 was formed so as to cover an end portion of the pixel electrode 102 provided on the substrate 101 and partition the pixel. The partition wall 103 is formed by forming a 2 μm-thick film on the entire surface of the substrate 101 by a spin coater method using a positive resist represented by a trade name “ZWD6216-6” manufactured by ZEON Corporation. A partition wall 103 was formed by patterning to a width of 40 μm. As a result, a pixel area of 960 × 240 dots and a pitch of 0.12 mm × 0.36 mm was defined.

  On the pixel electrode 102, molybdenum oxide having a film thickness of 50 nm was formed as a hole transport layer 104 by a reactive masking method using a shadow mask method. Due to the bottom emission structure, the metal film 10 nm and the oxide film 40 nm were formed from the interface of the pixel electrode 102 in consideration of the transmittance of the hole transport layer 104. The pattern region was formed using a metal mask having an opening of 120 mm × 100 mm so as to be formed on the entire display region.

  After that, the pixel electrode 102, the partition wall 103, and the hole transport formed on the substrate 101 using an ink in which a polyvinyl carbazole derivative, which is a material of the interlayer layer 105, is dissolved in toluene so as to have a concentration of 0.5%. The layer 104 is set as the printing substrate 302 of the relief printing apparatus 300, and the interlayer 105 is formed by relief printing in accordance with the line pattern just above the hole transport layer 104 on the pixel electrode 102 sandwiched between the partition walls 103. The printing was done. At this time, an anilox roll 305 of 300 lines / inch and a relief printing plate 307 made of a photosensitive resin were used. The thickness of the interlayer layer 105 after printing and drying was 10 nm.

  A pixel electrode 102, a partition wall 103, and a hole transport layer formed on the substrate 101 using an organic light emitting ink in which a polyphenylene vinylene derivative, which is an organic light emitting material of the organic light emitting layer 106, is dissolved in toluene so as to have a concentration of 1%. 104 and the interlayer layer 105 are set as the printing substrate 302 of the relief printing apparatus 300, and the organic light emitting layer 106 is printed by the relief printing method in accordance with the line pattern just above the interlayer layer 105 sandwiched between the partition walls 103. Went. At this time, an anilox roll 305 of 150 lines / inch and a relief printing plate 307 made of a photosensitive resin were used. The film thickness of the organic light emitting medium layer 110 after printing and drying was 80 nm.

  Thereafter, a calcium film is formed as a counter electrode 107 with a film thickness of 10 nm by a vacuum evaporation method using a metal mask having an opening of 120 mm × 100 mm, and then an aluminum film is used using a metal mask having an opening of 124 mm × 104 mm. The film was formed with a film thickness of 150 nm.

Thereafter, a glass plate was used as the sealing material 108 so as to cover the entire light emitting region, and the adhesive was thermally cured at about 90 ° C. for 1 hour for sealing. When the organic electroluminescent display device 100 thus obtained was driven, display characteristics of 100 cd / m ² at a luminance of 7 V, 11 cd / A at a luminous efficiency of 20 mA / cm ² were obtained, and a uniform light emission state without luminance unevenness Met.

  Before the formation of the hole transport layer 104, the same procedure as in Example 1 was performed. As the hole transport layer 104, vanadium oxide having a film thickness of 50 nm was formed into a pattern by a shadow mask method using a reactive sputtering method. did. Due to the bottom emission structure, the metal film 15 nm and the oxide film 35 nm are formed from the interface of the pixel electrode 102 in consideration of the transmittance of the hole transport layer 104. Thereafter, the interlayer layer 105, the organic light emitting layer 106, the counter electrode 107, and the sealing material 108 were produced in the same procedure as in Example 1.

When the organic electroluminescence display device 100 thus obtained was driven, the display characteristics of 100 cd / m ² at a luminance of 7 V and 10 cd / A at a luminous efficiency of 20 mA / cm ² were obtained, and uniform light emission was achieved. It was in a state.

[Comparative Example 1]
Before the formation of the hole transport layer 104, it was prepared in the same procedure as in Example 1, and PEDOT / PSS (polyethylenedioxythiophene / polystyrene sulfonic acid) was used as the hole transport layer 104 to a thickness of 50 nm by spin coating. A film was formed. Thereafter, the interlayer layer 105, the organic light emitting layer 110, the counter electrode 107, and the sealing material 108 were produced in the same procedure as in Example 1.

When the organic electroluminescent display device 100 thus obtained was driven, a display characteristic of 100 cd / m ² at a luminance of 8 V, a display characteristic of 8 cd / A at a luminous efficiency of 20 mA / cm ² was obtained, and a uniform light emission state without luminance unevenness Met.

  By using the hole transport layer 104 as an inorganic compound and having a composition ratio gradient in the film thickness direction, hole injection was efficiently performed, and a highly efficient organic electroluminescent display device 100 could be obtained.

  As a result of an accelerated test of the manufactured Example 1, Example 2 and Comparative Example 1 in a constant temperature and high humidity environment with a temperature of 50 ° C. and a humidity of 90%, dark spots were found on the light emitting surface of Comparative Example 1 after 1400 hours. However, in Example 1 and Example 2, the dark spot did not occur even after 2000 hours, and the organic electroluminescence display device 100 having no display defect could be obtained.

1 is a schematic cross-sectional view showing an organic light emitting display device according to an embodiment of the present invention. It is an example of the formation conditions of the positive hole transport layer which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the relief printing apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Organic electroluminescent display apparatus 101 Substrate 102 Pixel electrode 103 Partition 104 Hole transport layer 105 Interlayer layer 106 Organic light emitting layer 107 Counter electrode 108 Sealing material 109 Sealing resin 110 Organic light emitting medium layer 111 Sealing body 300 Letterpress printing apparatus 301 Stage 302 Printed Substrate 303 Ink Tank 304 Ink Chamber 305 Anilox Roll 306 Doctor 307 Letterpress 308 Plate Cylinder 309 Ink Layer

Claims (3)

A substrate,
A first electrode formed on the substrate;
Wherein formed on the first electrode, an organic light emitting medium layer having a plurality of layers including a hole transport layer and the hole to be formed transport layer organic light-emitting layer including an oxide of a transition metal 及 benefactor,
A second electrode formed on the organic light emitting medium layer,
The hole transport layer has a composition ratio gradient with respect to the film thickness direction, the first electrode side is the transition metal , and the organic light emitting layer side is an oxide of the transition metal ,
The organic electroluminescent display device, wherein the hole transport layer has a work function that increases from the first electrode side to the organic light emitting layer side. Prepare the board
Forming a first electrode on the substrate;
A plurality including a hole transport layer and the hole transport layer organic light-emitting layer formed on having a composition ratio gradient in the film thickness direction have a transition metal oxide 及 patron on the first electrode Forming an organic light emitting medium layer having a layer;
Forming a second electrode on the organic light emitting medium layer;
Forming the hole transport layer includes forming the transition metal with an inert gas at the start of film formation, and introducing a reactive gas with time to form an oxide of the transition metal ,
The method for manufacturing an organic light emitting display device, wherein the hole transport layer has a work function that increases from the first electrode side to the organic light emitting layer side. 3. The method of manufacturing an organic light emitting display device according to claim 2, wherein the hole transport layer is formed by physical vapor deposition.

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