JP2008034362A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element with voltage fall due to resistance of a transparent electrode of a translucent electrode alleviated, with fluctuation of emission brightness well restrained even with a large emission area, and capable of uniform light emission. <P>SOLUTION: The organic electroluminescent element provided with a first electrode consisting of a transparent electrode or a translucent electrode, a second electrode opposed to the first electrode, and at least one layer of organic layer fitted between the first electrode and the second electrode, is further provided with a frame-shaped first auxiliary electrode arranged on the surface of the first electrode and electrically connected with the first electrode, and a second auxiliary electrode arranged inside a frame of the first auxiliary electrode and constituted of a thin-line electrode electrically connected with the first auxiliary electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element useful as a light emitting element used in a planar light source, a segment display device, a dot matrix display device, a liquid crystal display device and the like.

  In recent years, in display devices and lighting devices, an organic electroluminescent element having a two-layer structure in which an organic fluorescent dye is used as a light emitting layer and an organic charge transport compound used in an electrophotographic photoreceptor or the like is laminated (hereinafter, referred to as “light emitting layer”). The use of organic EL elements) is being studied.

  However, in a display device or lighting device using these organic EL elements, the voltage drop due to the wiring resistance of the transparent electrode or translucent electrode cannot be ignored as the light emitting area increases, and the unevenness of the light emission luminance increases. There is a problem that.

  In order to solve such a problem, for example, in Japanese Unexamined Patent Application Publication No. 2004-14128 (Patent Document 1), in a planar light emitting device using an organic EL element, the transparent electrode of the organic EL element is used as the transparent electrode. A planar light emitting device in which an auxiliary electrode having a resistance lower than that of an electrode is electrically connected is disclosed. In the specification, the auxiliary electrode is thick at a portion near the connection terminal and thin at a portion far from the connection terminal, so that the current value is high and the light emission is strong at the portion near the connection terminal, but the aperture ratio is small, and the current at the portion far from the connection terminal. Although the value is small and the light emission is weak, since the aperture ratio is large, it is described that unevenness of the light emission luminance as a whole can be suppressed.

However, even when an organic EL element as described in Patent Document 1 is used, the current value becomes small at a portion far from the connection terminal, and thus unevenness in the light emission luminance cannot be sufficiently suppressed. In addition, there is a problem in that the light use efficiency is lowered when unevenness of the light emission luminance is suppressed while adjusting the aperture ratio.
Japanese Patent Laid-Open No. 2004-14128

  The present invention has been made in view of the above-described problems of the prior art, reduces the voltage drop due to the resistance of the transparent electrode or the translucent electrode, and even when the emission area is large, the unevenness of the emission luminance is sufficiently suppressed, An object of the present invention is to provide an organic electroluminescence device capable of uniform light emission.

  As a result of intensive studies to achieve the above object, the present inventor has obtained a first electrode composed of a transparent electrode or a translucent electrode, a second electrode facing the first electrode, the first electrode, and the first electrode. In an organic electroluminescence device comprising at least one organic layer provided between two electrodes, an auxiliary electrode is arranged in a specific form on the surface of the first electrode, thereby forming a transparent electrode or a translucent electrode. The inventors have found that the voltage drop due to the resistance can be reduced, and that unevenness in light emission luminance can be sufficiently suppressed even when the light emission area is large, and the present invention has been completed.

That is, the organic electroluminescence element of the present invention is provided between the first electrode made of a transparent electrode or a semi-transparent electrode, the second electrode facing the first electrode, and the first electrode and the second electrode. An organic electroluminescence device comprising at least one organic layer,
A frame-shaped first auxiliary electrode disposed on the surface of the first electrode and electrically connected to the first electrode;
A second auxiliary electrode which is arranged in a frame of the first auxiliary electrode and is constituted by a thin wire electrode electrically connected to the first auxiliary electrode;
It is characterized by providing.

  Moreover, in the organic electroluminescent element of the present invention, the ratio of the line width between the second auxiliary electrode and the first auxiliary electrode (the line width of the second auxiliary electrode / the line width of the first auxiliary electrode) is A range of 1/1000 to 1/10 is preferable.

  Furthermore, in the organic electroluminescence element of the present invention, the first auxiliary electrode and the second auxiliary electrode may be disposed on the surface of the first electrode opposite to the organic layer. preferable.

  In the organic electroluminescence element of the present invention, the first electrode is partitioned into a plurality of electrically separated cells, and the plurality of cells are electrically connected to each other by the second auxiliary electrode. Preferably it is.

  The planar light source of the present invention comprises the organic electroluminescence element. Moreover, the segment display apparatus of this invention is equipped with the said organic electroluminescent element, It is characterized by the above-mentioned. Furthermore, the dot matrix display device of the present invention is characterized by comprising the organic electroluminescence element. Moreover, the liquid crystal display device of the present invention comprises the organic electroluminescence element.

  In addition, according to the organic electroluminescent element of the present invention, the voltage drop due to the resistance of the transparent electrode or the translucent electrode is reduced, and even when the light emitting area is wide, unevenness in light emission luminance is sufficiently suppressed, and uniform light emission is possible. . That is, in the organic electroluminescent element of the present invention, a frame-shaped first auxiliary electrode electrically connected to the first electrode on the surface of the first electrode made of a transparent electrode or a semi-transparent electrode, and the first A second auxiliary electrode is disposed which is disposed within a frame of the one auxiliary electrode and is configured by a thin wire electrode electrically connected to the first auxiliary electrode. Since the first auxiliary electrode and the second auxiliary electrode are made of a material having a lower electric resistance value than the first electrode, a voltage drop due to the resistance of the first electrode can be reduced.

  Furthermore, in the present invention, since the first auxiliary electrode has a wide line width and can pass a sufficient current, even if it is a portion where the distance from the connection terminal is long, it is almost affected by a voltage drop due to wiring resistance. Absent. In addition, the second auxiliary electrode is affected by a voltage drop due to wiring resistance because the line width is thin, but because the line width is thin, the amount of light emitted from the organic layer is small and the light utilization efficiency is reduced. The effect is small. In the present invention, since the second auxiliary electrode is disposed within the frame of the first auxiliary electrode and is electrically connected, even if the distance from the connection terminal is long, the wiring resistance The voltage drop due to is reduced. Therefore, according to the organic electroluminescent element of the present invention, the voltage drop due to the resistance of the transparent electrode or the semitransparent electrode is reduced, and even when the light emitting area is large, unevenness in the light emission luminance is sufficiently suppressed, and uniform light emission is possible. .

  In the present invention, the first electrode is divided into a plurality of electrically separated cells, and the plurality of cells are electrically connected to each other by the second auxiliary electrode. The light emission luminance can be further improved. That is, by dividing the first electrode into a plurality of electrically separated cells, it is possible to suppress light emission components that are guided in the surface direction of the first electrode, and it is possible to improve light emission luminance. . In addition, since the plurality of cells are electrically connected to each other by the second auxiliary electrode, unevenness in light emission luminance among the plurality of cells is sufficiently suppressed.

  According to the present invention, it is possible to provide an organic electroluminescence device capable of reducing the voltage drop due to the resistance of a transparent electrode or a translucent electrode, sufficiently suppressing unevenness in light emission luminance even when the light emission area is large, and capable of uniform light emission. Is possible.

  Hereinafter, the organic electroluminescence element of the present invention will be described in detail in accordance with preferred embodiments thereof.

The organic electroluminescent element of the present invention includes a first electrode made of a transparent electrode or a semitransparent electrode, a second electrode facing the first electrode, and at least provided between the first electrode and the second electrode. An organic electroluminescence device comprising one organic layer,
A frame-shaped first auxiliary electrode disposed on the surface of the first electrode and electrically connected to the first electrode;
A second auxiliary electrode which is arranged in a frame of the first auxiliary electrode and is constituted by a thin wire electrode electrically connected to the first auxiliary electrode;
It is characterized by providing.

(First electrode)
The 1st electrode concerning this invention is an electrode which consists of a transparent electrode or a semi-transparent electrode, Comprising: It becomes an anode of the organic electroluminescent element of this invention. As such a first electrode, a metal oxide, metal sulfide or metal thin film having a high electrical conductivity can be used, and a high transmittance can be suitably used. Can be used. Examples of the material of the first electrode include indium oxide, zinc oxide, tin oxide, and conductive glass composed of indium tin oxide (ITO), indium zinc oxide, and the like, which are composites thereof ( NESA, etc.), gold, platinum, silver, and copper are used. Among these, ITO, indium / zinc / oxide, and tin oxide are preferable.

  The film thickness of such a first electrode can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm.

  Moreover, when it is set as the structure which partitions off such a 1st electrode into the several cell electrically isolate | separated, the space | interval between adjacent cells is 1 micrometer-50 micrometers, Preferably it is 5 micrometers-30 micrometers. If the distance between adjacent cells is less than the lower limit, the light guided in the surface direction of the first electrode tends not to be sufficiently suppressed. Since it becomes smaller, the luminous efficiency tends to decrease.

  Further, the shape of the plurality of cells thus electrically separated is not particularly limited, and examples thereof include a rectangular shape such as a stripe shape, a triangular shape, and a quadrangular shape. In the case where such a first electrode is divided into a plurality of electrically separated cells, the first electrode is formed after forming the first organic electroluminescence element of the present invention. The material of what is to be done (for example, auxiliary electrode, organic layer) will be filled between adjacent cells.

  Examples of the method for forming the first electrode as described above include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Moreover, as a method of partitioning such a first electrode into a plurality of electrically separated cells, for example, there is a method of forming a pattern by an etching method using a photoresist after forming the first electrode.

  Note that a transparent conductive film made of an organic material such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used as the first electrode. In addition, from the viewpoint of facilitating charge injection into the organic layer, a conductive polymer such as a phthalocyanine derivative and a polythiophene derivative, Mo oxide, amorphous carbon, A 1 to 200 nm layer such as carbon fluoride or a polyamine compound, or a layer having an average film thickness of 10 nm or less made of a metal oxide, a metal fluoride, an organic insulating material, or the like may be provided.

(Auxiliary electrode)
In the organic electroluminescence element of the present invention, a frame-shaped first auxiliary electrode disposed on the surface of the first electrode and electrically connected to the first electrode;
A second auxiliary electrode which is arranged in a frame of the first auxiliary electrode and is constituted by a thin wire electrode electrically connected to the first auxiliary electrode;
It is necessary to have In the present invention, by arranging the first auxiliary electrode and the second auxiliary electrode on the surface of the first electrode in the above-described form, even when the light emitting area of the organic EL element is large, the unevenness of the light emission luminance is sufficient. Can be suppressed.

  Examples of the arrangement form of the first auxiliary electrode and the second auxiliary electrode include the arrangement forms shown in FIGS. 1, 2, 3, and 4. In the arrangement form shown in FIG. 1, the second auxiliary electrodes formed of thin wire electrodes are arranged in a lattice pattern within the frame of the frame-shaped first auxiliary electrode. Moreover, in the arrangement | positioning form shown in FIG. 2, the 2nd auxiliary electrode comprised by the thin wire electrode is arrange | positioned in the stripe form within the frame of the frame-shaped 1st auxiliary electrode. Further, in the arrangement form shown in FIG. 3, the second auxiliary electrode constituted by the thin wire electrode is arranged in a honeycomb shape within the frame of the frame-shaped first auxiliary electrode. In the arrangement shown in FIG. 4, the second auxiliary electrode constituted by the fine wire electrode is arranged in a lattice shape in the frame of the frame-shaped first auxiliary electrode, and further constituted by the fine thin wire electrode in the lattice. The second auxiliary electrodes are arranged in a grid pattern.

  Here, the shape of the frame-shaped first auxiliary electrode is not particularly limited as long as the second auxiliary electrode is formed in the frame, and examples thereof include a rectangular shape and a circular shape. The line width of the first auxiliary electrode can be appropriately selected according to the light emitting area of the organic electroluminescence element, but is preferably in the range of 1 to 50 mm, more preferably in the range of 3 to 20 mm. preferable. Furthermore, the line width of the thin wire electrode constituting the second auxiliary electrode (hereinafter referred to as “the line width of the second auxiliary electrode”) is preferably in the range of 1 to 200 μm from the viewpoint of light utilization efficiency. More preferably, it is in the range of -100 μm.

  In the present invention, the ratio of the line widths of the second auxiliary electrode and the first auxiliary electrode (the line width of the second auxiliary electrode / the line width of the first auxiliary electrode) is 1 / 1000-1 / 10 is preferable and 1/500 to 1/20 is more preferable. If the ratio of the line widths is within the above range, the light utilization efficiency tends to be further improved, and unevenness in light emission luminance tends to be further suppressed.

The material of the first auxiliary electrode and the second auxiliary electrode is not particularly limited as long as the electric conductivity is higher than the material of the first electrode, but usually has an electric conductivity of 10 ⁷ S / cm or more. A conductive material is used, and metal materials such as aluminum, silver, chromium, gold, copper, and tantalum are preferably used. Among these, aluminum, chromium, copper, and silver are more preferable from the viewpoint of high electrical conductivity and ease of material handling.

  In addition, when a metal is used as the material of the first auxiliary electrode and the second auxiliary electrode, the light from the organic layer described later is blocked, so the ratio of the area covered by the auxiliary electrode to the light emitting area of the element Is preferably 20% or more and 90% or less, more preferably 30% or more and 80% or less.

  Furthermore, the thicknesses of the first auxiliary electrode and the second auxiliary electrode can be appropriately selected so that the sheet resistance has a desired value, but is, for example, 10 to 500 nm, preferably 20 to 300 nm. More preferably, it is 50-150 nm.

  Furthermore, in the organic electroluminescence element of the present invention, the first auxiliary electrode and the second auxiliary electrode may be disposed on the surface of the first electrode on the organic layer side, It is preferable to arrange | position on the surface on the opposite side to an organic layer from a viewpoint of making the electrical connection with a 1st electrode, a said 1st auxiliary electrode, and a said 2nd auxiliary electrode more reliable.

  As a method for forming the first auxiliary electrode and the second auxiliary electrode as described above, a film of the material of the auxiliary electrode is formed by, for example, a vacuum deposition method, a sputtering method, or a laminating method in which a metal thin film is thermocompression bonded. Later, a method of forming a pattern by an etching method using a photoresist may be mentioned.

(Second electrode)
The 2nd electrode concerning this invention is an electrode arrange | positioned facing said 1st electrode, Comprising: It becomes a cathode of the organic electroluminescent element of this invention. As a material of such a second electrode, a material having a small work function is preferable, for example, lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium. , Indium, cerium, samarium, europium, terbium, ytterbium, and other metals and alloys of two or more thereof; or one or more of them and gold, silver, platinum, copper, manganese, titanium, cobalt Alloy with one or more of nickel, tungsten, tin; graphite or graphite intercalation compounds are used. Examples of these alloys include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, and calcium-aluminum alloy.

  The film thickness of such a second electrode can be appropriately selected in consideration of electrical conductivity and durability, but is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

  Examples of the method for forming the second electrode as described above include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded. Such a second electrode may have a laminated structure of two or more layers. Further, a layer made of a conductive polymer or a layer made of a metal oxide, a metal fluoride, an organic insulating material or the like having an average film thickness of 2 nm or less may be provided between the second electrode and the organic layer.

(Organic layer)
The organic layer according to the present invention is a layer provided between the first electrode and the second electrode. Such an organic layer may be a layer containing at least one light emitting material, but may be composed of a plurality of layers. The operation of the organic electroluminescent device essentially consists of the process of injecting electrons and holes from the electrode, the process of electrons and holes moving through the organic layer, the recombination of electrons and holes, and singlet excitons. Or, it consists of a process of generating triplet excitons and a process of emitting the excitons, but when the organic layer is composed of multiple layers, the functions required in each process are shared by multiple materials. And each material can be optimized independently. In addition to the three primary colors of red, blue, and green, examples of the light emission color of such an organic layer include intermediate color and white light emission. The full color element preferably emits light of three primary colors, and the planar light source emits light of white or intermediate color.

  In the present invention, not only the low molecular weight light emitting material (i) but also the polymer light emitting material (ii) can be used as the light emitting material used for such an organic layer. Depending on the type of such a light emitting material, other materials used in the organic layer are different. Therefore, it is divided into a case where a low molecular weight light emitting material (i) is used and a case where a polymer light emitting material (ii) is used. Each will be explained.

(I) In the case of using a low molecular type light emitting material As a material of the organic layer in the case of using a low molecular type light emitting material, “Organic EL display” (Co-authored by Shizuo Tokito, Chiya Adachi, Hideyuki Murata, published by Ohm Co., Ltd. 2004 First edition, first printing)) Fluorescence and phosphorescent materials, hole transport materials, electron block materials, hole block materials, electron transport materials described on pages 17-48, 83-99, 101-120. It is done. Specifically, as a hole transport material, JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-20988, JP-A-2-311591, JP-A-3-37992, JP-A-3-152184, JP-A-11-35687, JP-A-11-217392, JP-A-2000-80167, etc. Illustrated.

Furthermore, examples of the low molecular weight light emitting material (triplet light emitting complex) include, for example, Ir (ppy) ₃ and Btp ₂ Ir (acac) having iridium as a central metal, PtOEP having platinum as a central metal, and europium as a central metal. Eu (TTA) ₃ phen. Specifically, for example, Nature, (1998), 395, 151, Appl. Phys. Lett. (1999), 75 (1), 4, Proc. SPIE-Int. Soc. Opt. Eng. (2001), 4105 (Organic Light-Emitting Materials and Devices IV), 119, J. Am. Chem. Soc., (2001), 123, 4304, Appl. Phys. Lett., (1997), 71 (18), 2596, Syn. Met., (1998), 94 (1), 103, Syn. Met., (1999), 99 (2), 1361, Adv. Mater., (1999), 11 (10), 852, Jpn. Examples are those described in Appl. Phys., 34, 1883 (1995) and the like.

  The thickness of the layer containing the material of these organic layers is appropriately selected so that the light emission efficiency and the driving voltage have desired values, but is generally 5 to 200 nm. Moreover, the thickness of a positive hole transport layer is 10-100 nm, for example, Preferably it is 20-80 nm. The thickness of the light emitting layer is, for example, 10 to 100 nm, and preferably 20 to 80 nm. The thickness of the hole blocking layer is, for example, 5 to 50 nm, preferably 10 to 30 nm. The thickness of the electron injection layer is, for example, 10 to 100 nm, and preferably 20 to 80 nm.

  As a method for forming these layers, in addition to vacuum processes such as vacuum deposition, cluster deposition, molecular beam deposition, etc., those capable of forming solubility and emulsion can be formed by a coating method or a printing method described later. Can be mentioned.

(Ii) In the case of using a polymer-type light emitting material As a material of the organic layer in the case of using a polymer-type light-emitting material, “polymer EL material” (Toshihiro Onishi and Tamami Koyama co-authored by Kyoritsu Shuppan, published in 2004, first edition, first edition) ) The materials described on pages 33 to 58 can be mentioned, and an organic electroluminescence device can be constructed with a structure laminated with a charge injection layer or a charge transport layer. More specifically, examples of the hole transport material, the electron transport material, and the light emitting material of the polymer compound include WO99 / 13692 publication specification, WO99 / 48160 publication specification, GB2340304A, WO00 / 53656 publication specification, WO01. / 19834 published specification, WO00 / 55927 published specification, GB2348316, WO00 / 46321 published specification, WO00 / 06665 published specification, WO99 / 54943 published specification, WO99 / 54385 published specification, US5777070, WO98 / 06773 published specification , WO97 / 05184 published specification, WO00 / 35987 published specification, WO00 / 53655 published specification, WO01 / 34722 published specification, WO99 / 24526 published specification, WO00 / 22027 published specification, WO00 / 2026 published specification, WO98 / 27136 published specification, US573636, WO98 / 12162 published specification, US5741921, WO97 / 09394 published specification, WO96 / 29356 published specification, WO96 / 10617 published specification, EP07070720, published WO95 / 07955 Description, JP 2001-181618 A, JP 2001-123156 A, JP 2001-3045 A, JP 2000-351967 A, JP 2000-303066 A, JP 2000-299189 A JP, 2000-252065, JP 2000-136379, JP 2000-104057, JP 2000-80167, JP 10-324870, JP 10-114891 Polyfluorenes, derivatives and copolymers thereof, polyarylenes, derivatives and copolymers thereof, polyarylene vinylenes, derivatives and copolymers disclosed in JP-A-9-111233, JP-A-9-45478, etc. And (co) polymers of polymers, aromatic amines and derivatives thereof. These polymer light-emitting materials and charge transport materials may be mixed with the light-emitting materials and charge transport materials used for the organic layer when the above-described low-molecular light-emitting materials are used. Further, in these polymer light emitting materials and charge transport materials, the above-described low molecular light emitting materials may be included in the structure of these materials.

  As a specific example of the charge injection layer, a layer containing a conductive polymer or a positive electrode included between the first electrode material and the hole transport layer provided between the first electrode and the hole transport layer. A layer containing a material having an ionization potential of an intermediate value with respect to the hole transporting material, provided between the second electrode and the electron transport layer, and included in the material of the second electrode and the electron transport layer Examples thereof include a layer containing a material having an electron affinity with a value intermediate to that of the material.

When such a charge injection layer is a layer containing a conductive polymer, the layer containing the conductive polymer is adjacent to the electrode between at least one of the electrodes (first electrode and second electrode) and the light emitting layer. Provided.
The electric conductivity of such a conductive polymer is preferably 10 ⁻⁷ S / cm or more and 10 ³ S / cm or less. In order to reduce the leakage current between the light emitting pixels, 10 ⁻ It is more preferably ⁵ S / cm or more and 10 ² S / cm or less, and particularly preferably 10 ⁻⁵ S / cm or more and 10 ¹ S / cm or less. Also, usually, in order to make the electric conductivity of such a conductive polymer 10 ⁻⁵ S / cm or more and 10 ³ S / cm or less, such a conductive polymer is doped with an appropriate amount of ions. To do.

  As the ions to be doped, an anion is used for the hole injection layer, and a cation is used for the electron injection layer. Examples of the anion include polystyrene sulfonate ion, alkylbenzene sulfonate ion, camphor sulfonate ion, and the like, and examples of the cation include lithium ion, sodium ion, potassium ion, tetrabutylammonium ion, and the like.

  The material used for the charge injection layer may be appropriately selected depending on the material of the electrode and the adjacent layer. Polyaniline and its derivatives, polythiophene and its derivatives, polypyrrole and its derivatives, polyphenylene vinylene and its derivatives, polythieny Lembinylene and its derivatives, polyquinoline and its derivatives, polyquinoxaline and its derivatives, conductive polymers such as polymers containing an aromatic amine structure in the main chain or side chain; metal phthalocyanine (copper phthalocyanine, etc.); carbon, etc. It is done.

  Further, for the purpose of facilitating charge injection, an insulating layer having a thickness of 10 nm or less may be provided adjacent to the first electrode and / or the second electrode. Examples of the material for such an insulating layer include metal fluorides, metal oxides, organic insulating materials, and the like, and metal fluorides and metal oxides such as alkali metals or alkaline earth metals are preferable.

  The electron transporting polymer material contained in the organic layer near the second electrode is not particularly limited as long as it is a polymer material in which electrons are injected and transported from the electrode. A polymer material containing a polymer or an electron transporting group in the polymer can be used as appropriate. Further, a low molecular electron transporting material can be used in combination.

  In addition to charge transport, these hole transport materials and electron transport materials can also be used preferably having a light emitting mechanism. In the present invention, these layers are doped with the light emitting material. It can also be used.

  The thickness of the layer containing the organic layer material as described above has an optimum value depending on the material used, but can be appropriately selected so that the driving voltage and the light emission efficiency become appropriate values. Moreover, the thickness of a light emitting layer is 5-300 nm, for example, Preferably it is 30-200 nm, More preferably, it is 40-150 nm. The thickness of the charge injection layer is, for example, 1 nm to 1000 nm, preferably 2 nm to 100 nm. The thickness of the electron transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

  Examples of the method for forming a layer (light emitting layer, charge transport layer, charge injection layer) containing a polymer material among the organic layer materials described so far include, for example, a coating method from a solution and a printing method. The method of forming into a film is mentioned. Such a method can also be employed as a method of forming a layer (light emitting layer, charge transport layer, charge injection layer) that does not contain the polymer material. According to such a method, it is only necessary to remove the solvent by drying after applying the solution, and the same technique can be applied even when a charge transport material or a light emitting material is mixed, which is very advantageous in production. is there. Such coating methods and printing methods include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and screen printing. Examples thereof include coating methods such as a method, a flexographic printing method, an offset printing method, a capillary coating method, a nozzle coating method, and an inkjet printing method. In addition, the charge injection material can be formed into a film in the form of an emulsion and dispersed in water or alcohol by the same method as the solution.

  In such a coating method or printing method, the solvent used for the material of the organic layer is not particularly limited, but a solvent capable of dissolving or uniformly dispersing the polymer material is preferable. In the case where the polymer material is soluble in a non-polar solvent, examples of such a solvent include a chlorine-based solvent such as chloroform, methylene chloride, and dichloroethane; an ether-based solvent such as tetrahydrofuran; toluene, xylene, Aromatic hydrocarbon solvents such as tetralin, anisole, n-hexylbenzene, and cyclohexylbenzene; aliphatic hydrocarbon solvents such as decalin and bicyclohexyl; ketone solvents such as acetone, methyl ethyl ketone, and 2-heptanone; ethyl acetate, Examples include ester solvents such as butyl acetate, ethyl cellosolve acetate, and propylene glycol monomethyl ether acetate.

  In the case of laminating a plurality of layers, it is preferable to insolubilize the first formed layer in order to prevent mixing of the upper and lower layers. As a method for insolubilization in this way, a soluble precursor or a polymer having a soluble group is used, and the precursor is converted into a conjugated polymer by heat treatment or dissolved by decomposing the soluble group. A method of insolubilizing by lowering, a method of using a hole transporting polymer having a crosslinking group in the molecule, a method of mixing a monomer or a macromer that causes a crosslinking reaction by heat, light, electron beam, etc. Can be mentioned.

  Examples of such a crosslinking group include polymers having a vinyl group, a (meth) acrylate group, an oxetane group, a cyclobutadiene group, a diene group, and the like in the side chain. The introduction rate of these groups is not particularly limited as long as it is insolubilized with respect to the solvent used during the film formation of the electron transporting polymer. It is mass%, More preferably, it is 1-10 mass%.

  The monomer or macromer that causes a crosslinking reaction is a compound having a weight average molecular weight of 2000 or less in terms of polystyrene, and has two or more groups such as a vinyl group, a (meth) acrylate group, an oxetane group, a cyclobutadiene group, and a diene group. Things. Furthermore, compounds that can cross-link between molecules such as acid anhydride groups and cinnamic acid are also exemplified. As these examples, those described in “Current Status and Prospect of UV / EB Curing Technology” (supervised by Kunihiro Ichimura, CMC Publishing Co., Ltd., published in 2002, first edition, first printing, chapter 2) can be suitably used.

  Furthermore, when a polymer compound is used as the material for the organic layer, its purity affects the performance of the device such as charge transport properties and light emission properties, so the monomer before polymerization is distilled, sublimated, purified, recrystallized, etc. Polymerization is preferably performed after purification by column chromatography. In addition, after the polymerization, purification is performed by conventional separation operations such as acid washing, alkali washing, neutralization, water washing, organic solvent washing, reprecipitation, centrifugation, extraction, column chromatography, dialysis, purification operation, drying and other operations. It is preferable to

(Organic electroluminescence device)
The organic electroluminescence element of the present invention can be produced by forming the above-described first electrode, second electrode, first auxiliary electrode, second auxiliary electrode, and organic layer on a support substrate. Such a support substrate may be any substrate that does not change when an organic electroluminescence element is produced, and examples thereof include glass, plastic, a polymer film, and a silicon substrate. In addition, when taking out the light from the said organic layer from such a support substrate side, it is preferable to use a transparent thing as a support substrate. The element structure of the organic electroluminescence element of the present invention is not particularly limited, and may be a top emission type or a bottom emission type. Further, the order in which the first electrode and the like are formed on the support substrate can be appropriately selected according to such an element structure. Furthermore, in the organic electroluminescent element of this invention, you may provide a protective layer as needed. Examples of the material for such a protective layer include glass, plastic, a polymer film, a silicon substrate, and a photo-curing resin such as an acrylic resin. These protective layer materials may be used alone or in combination of two or more. In addition, when taking out the light from the said organic layer from such a protective layer side, it is preferable to use a transparent thing as a material of a protective layer.

  As described above, the organic electroluminescence element of the present invention is a curved or flat surface light source for backlight or illumination of liquid crystal displays; segment display devices used in interiors and advertisements, dot matrix display devices, liquid crystals It can be suitably used as a light emitting element used in a display device or the like.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. The compounds A to C represented by the following structural formulas (A) to (C) used in Synthesis Examples 1 and 2 were synthesized according to the method described in the published specification of WO2000 / 046321.

(Synthesis Example 1)
Polymer compound 1 represented by the following general formula (1) was synthesized by the following method.

  Specifically, first, 0.91 g of methyl trioctyl ammonium chloride (manufactured by Aldrich, trade name: Aliquat 336), 5.23 g of compound A, and 4.55 g of compound C were charged into a 200 ml separable flask in a reaction vessel. Thereafter, the inside of the reaction system was replaced with nitrogen gas. Thereafter, 70 ml of toluene was added, 2.0 mg of palladium acetate and 15.1 mg of tris (o-tolyl) phosphine were added, and the mixture was refluxed to obtain a mixed solution.

  Next, 19 ml of an aqueous sodium carbonate solution was added dropwise to the obtained mixed solution, and the mixture was stirred overnight under reflux. Then, 0.12 g of phenylboric acid was added, and the mixture was stirred for 7 hours. Thereafter, 300 ml of toluene was added, the reaction solution was separated, and the organic phase was washed with an aqueous acetic acid solution and water, and then an aqueous sodium N, N-diethyldithiocarbamate solution was added and stirred for 4 hours.

Next, after separating the mixed solution after stirring, the mixture was passed through a silica gel-alumina column, washed with toluene, dropped into methanol to precipitate a polymer, and then the obtained polymer was filtered and dried under reduced pressure. Dissolved in. And the obtained toluene solution was again dripped at methanol, the deposit was produced, this deposit was filtered and dried under reduced pressure, and 6.33g of high molecular compounds 1 were obtained. The obtained polymer compound 1 had a polystyrene equivalent weight average molecular weight Mw of 3.2 × 10 ⁵ and a polystyrene equivalent number average molecular weight Mn of 8.8 × 10 ⁴ .

(Synthesis Example 2)
Polymer compound 2 represented by the following general formula (2) was synthesized by the following method.

  That is, first, 22.5 g of compound B and 17.6 g of 2,2′-bipyridyl were charged into a reaction vessel, and the inside of the reaction system was replaced with nitrogen gas. Thereafter, 1500 g of tetrahydrofuran (dehydrated solvent) previously deaerated by bubbling with an argon gas was added to obtain a mixed solution. Then, 31 g of bis (1,5-cyclooctadiene) nickel (0) was added to the obtained mixed solution and stirred at room temperature for 10 minutes, and then reacted at 60 ° C. for 3 hours. The reaction was performed in a nitrogen gas atmosphere.

  Next, after cooling the obtained reaction solution, a mixed solution of 25% by mass of ammonia water 200 ml / methanol 900 ml / ion exchanged water 900 ml was poured into this solution and stirred for about 1 hour. Thereafter, the produced precipitate was collected by filtration, and this precipitate was dried under reduced pressure and then dissolved in toluene. And after filtering the obtained toluene solution and removing an insoluble matter, this toluene solution was refine | purified by letting it pass through the column filled with the alumina.

  Next, the purified toluene solution was washed with a 1N aqueous hydrochloric acid solution, allowed to stand and separated, and then the toluene solution was recovered. And this toluene solution was wash | cleaned with about 3 mass% ammonia water, and after leaving still and liquid-separating, the toluene solution was collect | recovered. Thereafter, this toluene solution was washed with ion-exchanged water, allowed to stand and separated, and the washed toluene solution was recovered.

Next, the washed toluene solution was poured into methanol to form a precipitate. The precipitate was washed with methanol and then dried under reduced pressure to obtain polymer compound 2. The obtained polymer compound 2 had a polystyrene equivalent weight average molecular weight of 8.2 × 10 ⁵ and a polystyrene equivalent number average molecular weight of 1.0 × 10 ⁵ .

(Example 1)
A glass substrate (100 mm × 100 mm) was used as a support substrate, and Cr having a thickness of 1000 nm was deposited on the support substrate by a DC sputtering method at 120 ° C. using Ar as a Cr target and a sputtering gas. The film forming pressure at this time was 0.5 Pa, and the sputtering power was 2.0 kW. After applying a resist on the Cr film and baking at 110 ° C. for 90 seconds, a square frame-shaped opening composed of a line having a line width of 20 mm and a vertical and horizontal pitch of 300 μm in the frame of the opening, respectively.・ Exposure with 200mJ energy through a photomask with 100μm, line width 70μm ・ 30μm grid type openings, development with 0.5% by weight potassium hydroxide aqueous solution, post-bake at 130 ° C for 110 seconds did. Next, the resist residue is peeled off by immersing in Cr etching solution at 40 ° C. for 120 seconds, patterning Cr, and finally immersing in a 2% by mass potassium hydroxide aqueous solution. One auxiliary electrode and a second auxiliary electrode) were formed.

Next, the first electrode was formed on the substrate on which the auxiliary electrode was formed. That is, ITO having a film thickness of 3000 nm was deposited by a DC sputtering method at 120 ° C. using an ITO firing target as the first electrode material and Ar as the sputtering gas. The film forming pressure at this time was 0.25 Pa, and the sputtering power was 0.25 kW. Thereafter, annealing was performed in an oven at 200 ° C. for 40 minutes. Thereafter, the substrate on which the first electrode is formed is ultrasonically cleaned using a weak alkaline detergent at 60 ° C., cold water, and hot water at 50 ° C., pulled up from the hot water at 50 ° C. and dried, and then washed with UV / O _{3 for} 20 minutes. Went.

Then, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (manufactured by Starck Vitech, trade name: BaytronP CH8000) is placed on the substrate after washing with a 0.45 μm diameter filter and 0.2 μm. A thin film with a thickness of 80 nm is formed by spin coating using the liquid filtered in the second stage using a filter having a diameter, and heat-treated at 200 ° C. for 15 minutes on a hot plate in an air atmosphere to form a hole injection layer Formed. Next, the polymer compound 1 and the polymer compound 2 obtained in Synthesis Examples 1 and 2 were weighed at a weight ratio of 1: 1 and dissolved in toluene to prepare a 1% by mass polymer solution. A polymer solution was spin-coated on a substrate on which a hole injection layer was formed to form a film with a thickness of 80 nm, and then heat-treated on a hot plate in a nitrogen atmosphere at 130 ° C. for 60 minutes to form a light emitting layer. . Thereafter, the substrate on which the light-emitting layer was formed was introduced into a vacuum vapor deposition machine, and LiF, Ca, and Al were sequentially deposited at a thickness of 2 nm, 5 nm, and 200 nm as a cathode to form a second electrode. It should be noted that metal deposition was started after the degree of vacuum reached 1 × 10 ⁻⁴ Pa or less. Finally, the surface of the second electrode on the substrate on which the second electrode is formed is covered with a glass plate in an inert gas, and further, the four sides are covered with a photo-curing resin, and then the photo-curing resin is cured to protect it. A layer was formed to produce an organic EL light emitting device.

  The organic EL light-emitting device thus obtained is shown in FIG. That is, the organic EL element shown in FIG. 5 includes a support substrate 1, a first auxiliary electrode 2, a second auxiliary electrode 3, a first electrode 4, a charge injection layer 5, a light emitting layer 6, a second electrode 7, and a protective layer 8. It has. An organic layer 11 composed of the charge injection layer 5 and the light emitting layer 6 is sandwiched between the first electrode 4 and the second electrode 7. The first auxiliary electrode 2 and the second auxiliary electrode 3 are disposed on the surface of the first electrode 4 opposite to the organic layer 11.

(Comparative Example 1)
Organic EL light emission for comparison as in Example 1 except that a photomask having only a square frame-shaped opening composed of a line having a line width of 20 mm was used as a photomask for forming the auxiliary electrode. An element was produced.

(Comparative Example 2)
As in the case of Example 1, except that a photomask having a lattice-type opening having a vertical and horizontal pitch of 300 μm and 100 μm and a line width of 70 μm and 30 μm was used as a photomask for forming the auxiliary electrode, respectively. Thus, an organic EL light emitting device for comparison was produced.

<Evaluation of light emission characteristics of organic EL light emitting device>
The light emission characteristics of the organic EL light emitting devices obtained in Example 1 and Comparative Examples 1 and 2 were evaluated. That is, the light emission luminance when a voltage of 8 V was applied to the entire device was measured, and the state of the light emitting surface was visually observed. The obtained results are shown in Table 1.

  As is clear from the results shown in Table 1, in the organic electroluminescence device of the present invention, it was confirmed that even when the emission area was large, unevenness in emission luminance was sufficiently suppressed and uniform emission was possible.

  As described above, according to the present invention, the voltage drop due to the resistance of the transparent electrode or the translucent electrode is reduced, and even when the light emitting area is large, the unevenness of the light emission luminance is sufficiently suppressed, and the organic electroluminescence capable of uniform light emission. A luminescence element can be provided.

  Therefore, the organic electroluminescence element of the present invention is useful as a light-emitting element used for a planar light source, a segment display device, a dot matrix display device, a liquid crystal display device and the like.

It is a schematic plan view which shows the positional relationship of the 1st auxiliary electrode arrange | positioned on the surface of the 1st electrode in suitable one Embodiment of the organic electroluminescent element of this invention, and a 2nd auxiliary electrode. It is a schematic plan view which shows the positional relationship of the 1st auxiliary electrode arrange | positioned on the surface of the 1st electrode in other suitable embodiment of the organic electroluminescent element of this invention, and a 2nd auxiliary electrode. It is a schematic plan view which shows the positional relationship of the 1st auxiliary electrode arrange | positioned on the surface of the 1st electrode in other suitable embodiment of the organic electroluminescent element of this invention, and a 2nd auxiliary electrode. It is a schematic plan view which shows the positional relationship of the 1st auxiliary electrode arrange | positioned on the surface of the 1st electrode in other suitable embodiment of the organic electroluminescent element of this invention, and a 2nd auxiliary electrode. It is a schematic sectional drawing which shows the laminated structure of the organic electroluminescent element obtained in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Support substrate, 2 ... 1st auxiliary electrode, 3 ... 2nd auxiliary electrode, 4 ... 1st electrode, 5 ... Charge injection layer, 6 ... Light emitting layer, 7 ... 2nd electrode, 8 ... Protective layer, 11 ... Organic layer.

Claims (8)

Organic comprising a first electrode made of a transparent electrode or a semi-transparent electrode, a second electrode facing the first electrode, and at least one organic layer provided between the first electrode and the second electrode An electroluminescence element,
A frame-shaped first auxiliary electrode disposed on the surface of the first electrode and electrically connected to the first electrode;
A second auxiliary electrode which is arranged in a frame of the first auxiliary electrode and is constituted by a thin wire electrode electrically connected to the first auxiliary electrode;
An organic electroluminescence device comprising:   The ratio of the line width between the second auxiliary electrode and the first auxiliary electrode (the line width of the second auxiliary electrode / the line width of the first auxiliary electrode) is in the range of 1/1000 to 1/10. The organic electroluminescent element according to claim 1.   3. The organic material according to claim 1, wherein the first auxiliary electrode and the second auxiliary electrode are disposed on a surface of the first electrode opposite to the organic layer. Electroluminescence element.   The first electrode is partitioned into a plurality of electrically separated cells, and the plurality of cells are electrically connected to each other by the second auxiliary electrode, respectively. The organic electroluminescent element as described in any one of them.   A planar light source comprising the organic electroluminescence element according to any one of claims 1 to 4.   The segment display apparatus provided with the organic electroluminescent element as described in any one of Claims 1-4.   A dot matrix display device comprising the organic electroluminescence element according to claim 1.   A liquid crystal display device comprising the organic electroluminescence element according to claim 1.