JP2006302814A - Method for forming organic electroluminescent layer, and organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a formation method of an organic compound layer that has improved flexibility in an element configuration, improves element performance, is efficient, and stable production without causing interlayer mixture even if a plurality of organic EL layers are laminated, and to provide a manufacturing method of an organic EL element using the organic compound layer. <P>SOLUTION: In the formation method of the organic EL layer for forming at least one organic EL layer made of at least a layer of organic compound containing a luminous layer at least on a support, an organic compound layer is applied onto an endless belt base to be driven continuously or intermittently, and the organic compound layer formed on the endless belt base is overlapped to the support carried in synchronization with the endless belt base for transferring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic electroluminescent element and a method for manufacturing the same, and more particularly to a method for manufacturing an organic electroluminescent element with low cost and high productivity using transfer in forming an organic electroluminescent layer.

  In recent years, the use of organic electroluminescence (EL) elements for light sources such as display devices such as flat displays, electrophotographic copying machines, and printers has been studied.

  This organic EL element is a current-driven light-emitting element that emits light by flowing a very thin thin film of a fluorescent organic compound between an anode (hereinafter also referred to as a first electrode) and a cathode (hereinafter also referred to as a second electrode). It is. Usually, the organic substance is an insulator, but by making the film thickness of the organic layer very thin, current can be injected and it can be driven as an organic EL element. It can be driven at a low voltage of 10 V or less, and it is possible to obtain highly efficient light emission.

  In particular, phosphorescent organic EL devices using excited triplets that far exceed the efficiency of conventional organic EL devices using excited singlets have been disclosed by S.C. R. Forrest et al. (Appl. Phys. Lett. (1999), 75 (1), 4-6). Furthermore, C.I. As reported by Adachi et al. (J. Appl. Phys., 90, 5048 (2001)), such an element is used not only for a display but also for illumination. Application to is expected.

  By the way, when manufacturing a lighting device or a full color panel using an organic EL element, the following situation must be considered.

  Currently, there are organic EL materials of low molecular weight materials and high molecular weight materials.

  In order to manufacture an organic EL element using a low molecular material, vapor deposition is performed at a high vacuum. Low molecular weight materials can be purified by sublimation, easy to purify, can use high-purity organic EL materials, and are easy to make a laminated structure, so they are very efficient in terms of efficiency and life. ing.

However, since the vapor deposition is performed under a high vacuum condition of 10 ⁻⁴ Pa or less, the operation is complicated and the cost is high, which is not always preferable from the viewpoint of production. Particularly in lighting applications, since elements must be formed in a large area, manufacturing is difficult by vapor deposition. In addition, phosphorescent dopants used in phosphorescent organic EL devices have a large area and no unevenness, and it is difficult to introduce a plurality of dopants into the device by vapor deposition. I must say that it is difficult.

  On the other hand, a wet process (wet method) such as a spin coat, ink jet, and printing can be adopted for manufacturing a high molecular material and a low molecular material that are in solution. In other words, since it can be manufactured under atmospheric pressure, there is an advantage that the cost can be reduced. Further, since it is prepared in a solution to form a thin film, it is easy to adjust the dopant, etc., and it is difficult to cause unevenness even in a large area. This can be said to be very advantageous in terms of cost and manufacturing technology for lighting applications of organic EL elements and full color panels.

  However, in order to obtain a laminated structure using a wet process, there is an influence of dissolution at the interface, the choice of materials and solvents is limited, and the material must be in a form that allows chemical and physical treatment. It must happen.

  In a method for manufacturing an organic EL element, as a method for efficiently and continuously forming an organic EL element, an organic EL element made of an organic compound is formed by vapor deposition using a roll-to-roll method. (For example, refer to Patent Document 1).

  As a method for mass-producing a large-area organic EL device at low cost, it is disclosed that a solution is continuously applied to form a hole injection layer and a light emitting layer (see, for example, Patent Document 2).

  In addition, a liquid layer composed of solvents that are not compatible with each other is applied adjacently, and a coating liquid in which a polymer organic material is dissolved in an aqueous solvent, and a coating liquid in which the polymer organic material is dissolved in an organic solvent. It has been disclosed that an organic EL layer is formed by simultaneous multilayer formation at the time of dissolution, such as coating adjacently (see, for example, Patent Document 3).

Furthermore, the lamination by transfer is less likely to be dissolved at the layer interface, and an organic EL element having high luminous efficiency and high element durability can be manufactured. As a method, an organic thin film layer in which light emitting pixels of three colors of blue, green and red are patterned is provided on a temporary support constituting a transfer material by a wet method. A transfer material is produced in advance, the transfer material is brought into close contact with the film forming substrate through a feeding mask, heated, and then the temporary support is peeled off, so that light emitting pixels of three colors of blue, green and red are patterned. A method of transferring a tempered organic thin film layer to the film forming substrate is disclosed (for example, see Patent Document 4).
International Publication No. 01/005194 Pamphlet Japanese Patent Laid-Open No. 10-77467 JP 2004-14172 A JP 2002-260854 A

  With respect to the method for manufacturing the organic EL element described above, according to Patent Document 1, it is possible to continuously and efficiently form the organic EL element, but the entire process must be performed under vacuum, and the equipment cost is reduced. In addition, there are problems in material use efficiency.

  Patent Document 2 describes that a solution is continuously applied to form a hole injection layer and a light-emitting layer, but in general, lamination by a wet method causes dissolution at the interface of each organic layer. Therefore, there are problems in light emission efficiency and device durability.

  Patent Document 3 describes that an organic EL layer is simultaneously formed in a multilayer state at the time of dissolution, and a laminated layer is formed by applying adjacent liquid layers that are not compatible with each other. However, there is a problem that it is easy to be subjected to the restriction of the solvent between the liquid layers when laminating and the disturbance of the interface during coating.

  In Patent Document 4, a transfer material wound in a roll is manufactured in advance, the transfer material is brought into close contact with a film forming substrate through a feeding mask, heated, and then the temporary support is peeled off. Transferring a thin film layer to the film-forming substrate is described. However, since the temporary support used in this example becomes waste, there is a problem from the viewpoint of cost and environment, and the roll-shaped transfer material forms a transfer layer in a separate process and is temporarily rolled. Therefore, foreign matter may adhere due to the mixing of foreign matter or peeling resistance during unwinding, and there is a problem in yield. Furthermore, since the film forming substrate is a single wafer, problems remain in terms of productivity such as handling.

  Although the present invention has been made in view of the above situation, when producing an organic EL element having a laminated structure, a method for producing an organic EL element capable of stable production without causing inter-layer mixing or interface disturbance. The purpose is to provide.

  In addition, an organic EL device that is environmentally friendly and does not generate waste during the production process or cause contamination or adhesion of foreign substances to the organic thin film layer, and that also improves yield and productivity. The purpose is to provide a creation method.

  It is another object of the present invention to provide a high-quality and high-productivity organic EL element that has high element configuration flexibility and improved element performance.

The above object is achieved by the following configuration.
(Claim 1)
In the method for forming an organic electroluminescence layer, at least one organic electroluminescence layer comprising at least one organic compound including a light emitting layer on a support is formed by transfer.
The organic compound layer is coated on an endless belt substrate that is driven continuously or intermittently, and then the organic compound layer formed on the endless belt substrate is conveyed in synchronization with the endless belt substrate. A method of forming an organic electroluminescence layer, wherein the transfer is performed on a body.
(Claim 2)
2. The method of forming an organic electroluminescent layer according to claim 1, wherein the coating of the organic compound is performed by forming a uniform film in a width perpendicular to the conveying direction of the endless belt base material. .
(Claim 3)
The method for forming an organic electroluminescent layer according to claim 1, wherein the coating of the organic compound is performed by an inkjet method.
(Claim 4)
4. The method for forming an organic electroluminescent layer according to claim 3, wherein the coating performed by the inkjet method is a pattern forming coating of at least one color.
(Claim 5)
The method for forming an organic electroluminescent layer according to any one of claims 1 to 4, further comprising a step of removing the solvent after coating the organic compound on the endless belt base material.
(Claim 6)
6. The endless belt base material is cleaned after the organic compound layer formed on the endless belt base material is transferred onto the support. 6. A method for forming an organic electroluminescence layer.
(Claim 7)
Static elimination treatment is performed on at least one of the upstream side and the downstream side in the transport direction of the support from the position where the organic compound layer is transferred from the support transported in synchronization with the endless belt base material coated with the organic compound layer. The method for forming an organic electroluminescence layer according to claim 1, wherein the organic electroluminescence layer is formed.
(Claim 8)
8. The organic electroluminescence layer according to claim 1, wherein the support conveyed in synchronization with the endless belt substrate is cleaned by oxygen plasma or UV irradiation. Method.
(Claim 9)
The organic electroluminescence layer is transferred to a support by the method for forming an organic electroluminescence layer according to any one of claims 1 to 8, and the organic electroluminescence layer is formed. A method for forming an organic electroluminescence layer, wherein the organic electroluminescence layer is wound up into a ru.
(Claim 10)
It is formed under an atmospheric environment having a dew point temperature of -20 ° C or lower and an JISB9920 standard cleanliness class 5 or lower, and an atmospheric condition of 10 ° C or higher and 45 ° C or lower, excluding the drying section. 10. The method for forming an organic electroluminescent layer according to any one of 9 above.
(Claim 11)
It manufactures with the formation method of the organic electroluminescent layer of any one of Claim 1 thru | or 10, The organic electroluminescent element characterized by the above-mentioned.
(Claim 12)
The organic electroluminescence device according to claim 11, wherein the light emission is based on phosphorescence.

  According to the present invention, even if a plurality of organic EL layers are laminated, no inter-layer mixing occurs, so that the element configuration is highly flexible, the element performance is improved, and the production is efficient and stable. It is possible to provide a method for forming an organic compound layer for forming an organic EL element with high quality and high productivity, and a manufacturing method for providing an organic EL element using the organic compound layer.

  Due to the above effects, the performance can be maintained even when the organic EL layer is formed of at least a single layer formed of a uniform film, and it can be used mainly for surface light sources such as illumination and backlight. It is possible to manufacture an organic EL element having an area.

  In addition, the above-described effects can maintain the performance even when the organic EL layer is formed with a pattern of at least one color and laminated, and a high-quality passive matrix full-color organic EL element can be produced. This can be used as a display device.

  Hereinafter, the constituent layers and general configuration of the organic EL element according to the present invention and the form of the method for forming the organic EL layer will be sequentially described.

<Structure layers and general structure of organic EL elements>
Although the preferable specific example of the layer structure of the organic EL element which concerns on this invention is shown below, it is not limited to the following forms.
(1) Anode / light emitting layer unit / electron transport layer / cathode (2) Anode / hole transport layer / light emitting layer unit / electron transport layer / cathode (3) Anode / hole transport layer / light emitting layer unit / hole blocking Layer / electron transport layer / cathode (4) anode / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer (hereinafter also referred to as electron injection layer) / cathode (5) anode / Anode buffer layer (hereinafter also referred to as hole injection layer) / hole transport layer / light emitting layer unit / hole blocking layer / electron transport layer / cathode buffer layer / cathode Here, the light emitting layer unit has a light emission maximum. There may be at least three light emitting layers having wavelengths of 430 nm to 480 nm, 510 nm to 550 nm, and 600 nm to 640 nm, respectively, and a non-light emitting intermediate layer may be provided between the light emitting layers.

  In the case of a white backlight (hereinafter also referred to as white BL), the light emitting unit uses a laminate of each color light emitting layer or a mixed material of each color light emitting material, and in the case of a full color, each color is patterned. To be achieved.

"anode"
As the anode in the organic EL element, an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ and ZnO. Alternatively, an amorphous material such as IDIXO (In ₂ O ₃ —ZnO) capable of forming a transparent conductive film may be used. For the anode, these electrode materials may be formed into a thin film by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by photolithography, or the pattern accuracy is not so required. (About 100 μm or more), the pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. Or when using the substance which can be apply | coated like an organic electroconductivity compound, wet film forming methods, such as a printing system and a coating system, can also be used. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

"cathode"
On the other hand, as the cathode, a material having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the point of durability against electron injection and oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than this, for example, a magnesium / silver mixture, Suitable are a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, a lithium / aluminum mixture, aluminum and the like. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. In order to transmit the emitted light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the emission luminance is advantageously improved.

  Moreover, after producing the said metal by the film thickness of 1 nm-20 nm to a cathode, the transparent or semi-transparent cathode can be produced by producing the electroconductive transparent material quoted by description of the anode on it, By applying this, an element in which both the anode and the cathode are transmissive can be manufactured.

  Next, an injection layer, a blocking layer, an electron transport layer, and the like used as a constituent layer of the organic EL element of the present invention will be described.

<< Injection layer: electron injection layer, hole injection layer >>
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, it exists between the anode and the light emitting layer or the hole transport layer and between the cathode and the light emitting layer or the electron transport layer. May be.

  An injection layer is a layer provided between an electrode and an organic layer in order to lower drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (November 30, 1998, NTS Corporation) Issue) ”, Chapter 2,“ Electrode Materials ”(pages 123 to 166) in detail, and a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer) are is there.

  The details of the anode buffer layer (hole injection layer) are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, and the like. Specific examples thereof include copper phthalocyanine. Phthalocyanine buffer layer typified by, oxide buffer layer typified by vanadium oxide, amorphous carbon buffer layer, polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene Etc.

  The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium or aluminum Metal buffer layer represented by lithium fluoride, alkali metal compound buffer layer represented by lithium fluoride, alkaline earth metal compound buffer layer represented by magnesium fluoride, oxide buffer represented by aluminum oxide Layer and the like. The buffer layer (injection layer) is preferably a very thin film, and the film thickness is preferably in the range of 0.1 nm to 5 μm, although it depends on the material.

<Blocking layer: hole blocking layer, electron blocking layer>
As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, as described in JP-A Nos. 11-204258 and 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT Corporation on November 30, 1998). There is a hole blocking layer that is applied.

  The hole blocking layer has a function of an electron transport layer in a broad sense, and is made of a hole blocking material that has a function of transporting electrons and has a remarkably small ability to transport holes. The probability of recombination of electrons and holes can be improved by blocking. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer as needed.

  In general, the hole blocking layer of the organic EL device is preferably provided adjacent to the light emitting layer.

  In the case of having a plurality of light emitting layers having different emission colors, it is preferable that the light emitting layer whose emission maximum wavelength is the shortest wave is closest to the anode among all the light emitting layers. It is preferable to additionally provide a hole blocking layer between the light emitting layer and the light emitting layer next to the anode next to the shortest wave light emitting layer. Furthermore, it is preferable that 50% by mass or more of the compound contained in the hole blocking layer provided at the position has an ionization potential of 0.3 eV or more higher than the host compound of the shortest wave emitting layer.

The ionization potential is defined by the energy required to emit an electron at the HOMO (highest occupied molecular orbital) level of the compound to the vacuum level, and can be obtained by the following method, for example.
(1) Using Gaussian 98 (Gaussian 98, Revision A.11.4, MJ Frisch, et al, Gaussian, Inc., Pittsburgh PA, 2002.), which is molecular orbital calculation software manufactured by Gaussian, USA. -The ionization potential can be obtained as a value obtained by rounding off the second decimal place of a value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G * as a word. This calculation value is effective because the correlation between the calculation value obtained by this method and the experimental value is high.
(2) The ionization potential can also be obtained by a method of directly measuring by photoelectron spectroscopy. Examples of the measurement method using photoelectron spectroscopy include a method using a low energy electron spectrometer “Model AC-1” (manufactured by Riken Keiki Co., Ltd.). It is also possible to use a measurement method by ultraviolet photoelectron spectroscopy.

  On the other hand, the electron blocking layer has a function of a hole transport layer in a broad sense, and is made of a material that has a function of transporting holes and has an extremely small ability to transport electrons, and transports electrons while transporting holes. By blocking, the recombination probability of electrons and holes can be improved. Moreover, the structure of the positive hole transport layer mentioned later can be used as an electron blocking layer as needed. The film thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 nm to 100 nm, and more preferably 5 nm to 30 nm.

<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May be the interface between the light emitting layer and the adjacent layer.

(Host compound)
The light emitting layer of the organic EL device of the present invention preferably contains the following host compound and phosphorescent compound (also referred to as phosphorescent compound).

  Here, in the present invention, the host compound is a compound contained in the light emitting layer, the mass ratio in the layer is 20% or more, and phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.). A rate is defined as a compound of less than 0.1. The phosphorescence quantum yield is preferably less than 0.01.

  As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. In addition, by using a plurality of phosphorescent compounds, it is possible to mix different light emission, thereby obtaining an arbitrary emission color. White light emission is possible by adjusting the kind of phosphorescent compound and the amount of doping, and can also be applied to illumination and backlight.

  As these known host compounds, compounds having a hole transporting ability and an electron transporting ability, preventing the emission of longer wavelengths, and having a high Tg (glass transition temperature) are preferable.

  Specific examples of known host compounds include compounds described in the following documents.

  JP-A-2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860, 2002-334787, 2002-15871, 2002-334788, 2002-43056, 2002-334789, 2002-75645, 2002-338579, 2002-105445 gazette, 2002-343568 gazette, 2002-141173 gazette, 2002-352957 gazette, 2002-203683 gazette, 2002-363227 gazette, 2002-231453 gazette, No. 003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060, No. 2002. -302516, 2002-305083, 2002-305084, 2002-308837, and the like.

  In the present invention, it has a plurality of light emitting layers, but it is preferable that 50% by mass or more of the host compound in each layer is the same compound because it is easy to obtain a uniform film property over the entire organic layer. It is preferable that the phosphorescence emission energy of the compound is 2.9 eV or more because it is advantageous for efficiently suppressing energy transfer from the dopant and obtaining high luminance.

(Phosphorescent compound (phosphorescent compound))
The material used for the light emitting layer (hereinafter referred to as the light emitting material) preferably contains a phosphorescent compound at the same time as the host compound. Thereby, it can be set as an organic EL element with higher luminous efficiency.

  The phosphorescent compound according to the present invention is a compound in which light emission from an excited triplet is observed, is a compound that emits phosphorescence at room temperature (25 ° C.), and has a phosphorescence quantum yield of 0.2 at 25 ° C. 01 or more compounds. The phosphorescence quantum yield is preferably 0.1 or more. The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of Experimental Chemistry Course 4 of the 4th edition. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence quantum yield used in the present invention only needs to achieve the above phosphorescence quantum yield in any solvent.

  There are two types of light emission of the phosphorescent compound in principle. One is the recombination of the carrier on the host compound to which the carrier is transported and the excited state of the host compound is generated, and this energy is phosphorescent. An energy transfer type in which light emission from the phosphorescent compound is obtained by transferring to the compound, and another is that the phosphorescent compound becomes a carrier trap, and carrier recombination occurs on the phosphorescent compound and the phosphorescent compound In any case, the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  The phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of the organic EL device.

  The phosphorescent compound used in the present invention is preferably a complex compound containing a group 8-10 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex). System compounds), rare earth complexes, and most preferred are iridium compounds.

  Although the specific example of a phosphorescent compound is shown below, this invention is not limited to these. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  In the present invention, the phosphorescence emission maximum wavelength of the phosphorescent compound is not particularly limited, and can be obtained in principle by selecting a central metal, a ligand, a ligand substituent, and the like. The emission wavelength can be changed.

  The light emission color of the organic EL device of the present invention and the compound according to the present invention is shown in FIG. 4.16 on page 108 of “New Color Science Handbook” (edited by the Japan Color Society, University of Tokyo Press, 1985). It is determined by the color when the result measured with the total CS-1000 (manufactured by Konica Minolta Sensing) is applied to the CIE chromaticity coordinates.

The white element referred to in the present invention means that the chromaticity in the CIE 1931 color system at 1000 Cd / m ² is X = 0.33 ± 0.77 when the front luminance at 2 ° viewing angle is measured by the above method. It is in the region of Y = 0.33 ± 0.77.

  The light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, and an ink jet method.

  In the white panel, it is preferable that the light emitting layer includes at least three layers having different emission spectra having emission maximum wavelengths in the range of 430 nm to 480 nm, 510 nm to 550 nm, and 600 nm to 640 nm, respectively. If it is three or more layers, there will be no restriction | limiting in particular. When there are more than four layers, there may be a plurality of layers having the same emission spectrum. A layer having an emission maximum wavelength in the range of 430 nm to 480 nm is referred to as a blue light emitting layer, a layer in the range of 510 nm to 550 nm is referred to as a green light emitting layer, and a layer in the range of 600 nm to 640 nm is referred to as a red light emitting layer.

  The total thickness of the light emitting layer is not particularly limited, but is usually 2 nm to 5 μm, preferably 2 nm to 200 nm. In the present invention, it is preferably in the range of 10 nm to 20 nm. If it is too thin, it is difficult to obtain film uniformity. If it is thicker than this, a high voltage is required to obtain light emission, which is not preferable. A film thickness of 20 nm or less is preferable because it has the effect of improving the stability of the emission color with respect to the driving current as well as the voltage surface.

  The film thickness of each light emitting layer is preferably selected in the range of 2 nm to 100 nm, and more preferably in the range of 2 nm to 20 nm. Although there is no restriction | limiting in particular about the film thickness relationship of each light emitting layer of blue, green, and red, It is preferable that the blue light emitting layer (the sum total when there are two or more layers) is the thickest among three light emitting layers.

  Moreover, in the range which maintains the said maximum wavelength, you may mix a several luminescent compound in each light emitting layer. For example, the blue light emitting layer may be used by mixing a blue light emitting compound having a maximum wavelength of 430 nm to 480 nm and a green light emitting compound having the same wavelength of 510 nm to 550 nm.

《Hole transport layer》
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.

  The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, oxadiazol derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives Fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

  The above-mentioned materials can be used as the hole transport material, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N'- Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) qua -Dryphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N- Diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and further described in US Pat. No. 5,061,569 Having two condensed aromatic rings in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3086 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] trimethyl triphenylamine unit described in Japanese Patent No. 8 is linked in three starburst types. Phenylamine (MTDATA) etc. are mentioned.

  Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.

  JP-A-11-251067, J. Org. Huang et. al. A so-called p-type hole transport material described in a book (Applied Physics Letters 80 (2002), p. 139) can also be used. In the present invention, it is preferable to use these materials because a light-emitting element with higher efficiency can be obtained.

  The hole transport layer is formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. Can do. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, a hole transport layer having high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, J.A. Appl. Phys. 95, 5773 (2004), and the like.

《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.

  Conventionally, in the case of a single electron transport layer and a plurality of layers, an electron transport material (also serving as a hole blocking material) used for an electron transport layer adjacent to the light emitting layer on the cathode side is injected from the cathode. As long as it has a function of transferring electrons to the light-emitting layer, any material can be selected and used from among conventionally known compounds. For example, nitro-substituted fluorene derivatives, diphenylquinone derivatives Thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazol derivatives, and the like. Further, in the above oxadiazol derivative, a thiadiazol derivative in which the oxygen atom of the oxadiazol ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. it can. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

  Also, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo). -8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc. , And metal complexes in which the central metal of these metal complexes is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC can be used. A semiconductor can also be used as an electron transport material.

  The electron transport layer can be formed by thinning the electron transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a printing method including an ink jet method, or an LB method. . Although there is no restriction | limiting in particular about the film thickness of an electron carrying layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5 nm-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Alternatively, an electron transport layer having high n property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175, J. Pat. Appl. Phys. 95, 5773 (2004), and the like.

<Support>
In general, as a support (hereinafter also referred to as a substrate, a substrate, a substrate, a support substrate, etc.) that can be used for an organic EL element, there is no particular limitation on the type of glass, plastic, etc., and it is transparent. May be opaque. In the case where light is extracted from the support side, the support is preferably transparent. Examples of the transparent support preferably used include glass, quartz, and a transparent resin film. A particularly preferable support used in the present invention is a resin film capable of giving flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulosic triacetate, and cellulose acetate. Cellulose esters such as tobutyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate (TAC) and cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol Polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide, polyethersulfone (PES), polyphenylene sulfide, polysulfones, Lier Terimide, Polyether Ketoneimide, Polyamide, Fluororesin, Nylon, Polymethylmethacrylate, Acrylic or Polyarylate, Aton (trade name, manufactured by JSR) or Apel (trade name, manufactured by Mitsui Chemicals) ) And the like. An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film, and it is preferably a barrier film having a water vapor permeability of 0.01 g / m ² / day / atm or less. Furthermore, a high barrier film having an oxygen permeability of 10 ⁻³ ml / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less is preferable.

  As a material for forming the barrier film, any material may be used as long as it has a function of suppressing intrusion of an element such as moisture or oxygen that causes deterioration of the element. For example, silicon oxide, silicon dioxide, silicon nitride, or the like can be used. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of organic materials. Although there is no restriction | limiting in particular about the lamination | stacking order of an inorganic layer and an organic layer, It is preferable to laminate | stack both alternately several times.

  The method for forming the barrier film is not particularly limited. For example, a vacuum deposition method, a sputtering method, a reactive sputtering method, a molecular beam epitaxy method, a cluster ion beam method, an ion plating method, a plasma polymerization method, a large size, and the like. An atmospheric pressure plasma polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used, but an atmospheric pressure plasma weight as described in JP-A-2004-68143 is used. A legal method is particularly preferred.

  Examples of the opaque support include metal plates / films such as aluminum and stainless steel, opaque resin substrates, and the like.

<Sealing>
As a sealing means used for this invention, the method of adhere | attaching a sealing member, an electrode, and a support body with an adhesive agent can be mentioned, for example.

  Generally, the sealing member may be disposed so as to cover the display area of the organic EL element, and may be a concave plate shape or a flat plate shape. Further, transparency and electrical insulation are not particularly limited.

Specific examples include a glass plate, a polymer plate / film, and a metal plate / film. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium, and tantalum. In the present invention, a polymer film and a metal film can be preferably used because the support has flexibility and the device can be thinned. Furthermore, the polymer film preferably has an oxygen permeability of 10 ⁻³ ml / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less.

  Specific examples of adhesives include photocuring and thermosetting adhesives having reactive vinyl groups of acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. Can be mentioned. Moreover, the heat | fever and chemical curing types (two-component mixing), such as an epoxy type, can be mentioned. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Moreover, a cationic curing type ultraviolet curing epoxy resin adhesive can be mentioned.

  In addition, since an organic EL element may deteriorate by heat processing, what can be adhesive-hardened from room temperature to 80 degreeC is preferable. A desiccant may be dispersed in the adhesive. Application | coating of the adhesive agent to a sealing part may use a commercially available dispenser, and may print it like screen printing.

  In addition, it is also preferable to coat the electrode and the organic layer on the outside of the electrode facing the support with the organic layer interposed therebetween, and form an inorganic or organic layer in contact with the support to form a sealing film. it can. In this case, the material for forming the film may be any material that has a function of suppressing intrusion of elements that cause deterioration of the element such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like is used. it can. Furthermore, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and layers made of organic materials. The method for forming these films is not particularly limited. For example, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam, ion plating, plasma polymerization, An atmospheric pressure plasma polymerization method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

  In the gap between the sealing member and the display area of the organic EL element, an inert gas such as nitrogen or argon, or an inert liquid such as fluorinated hydrocarbon or silicon oil is injected in the gas phase and the liquid phase. Is also possible. A vacuum can also be used. Moreover, a hygroscopic compound can also be enclosed inside.

  Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, etc.). Metal halides (eg, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchloric acids (eg, barium perchlorate, In particular, anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.

《Light extraction processing》
An organic electroluminescence element emits light inside a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1), and only 15% to 20% of the light generated in the light emitting layer. It is generally said that it cannot be taken out. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ greater than the critical angle causes total reflection and cannot be taken out of the device, or between the transparent electrode or light emitting layer and the transparent substrate. This is because light is totally reflected between the light and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the direction of the side surface of the device.

  As a technique for improving the light extraction efficiency, for example, a method of forming irregularities on the surface of the transparent substrate to prevent total reflection at the interface between the transparent substrate and the air (for example, US Pat. No. 4,774,435). A method for improving efficiency by providing a substrate with a light condensing property (for example, JP-A-63-314795). A method of forming a reflective surface on the side surface of the element (for example, Japanese Patent Laid-Open No. 1-220394). A method of forming an antireflection film by introducing a flat layer having an intermediate refractive index between a substrate and a light emitter (for example, Japanese Patent Application Laid-Open No. 62-172691). A method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter (for example, JP-A-2001-202827). There is a method of forming a diffraction grating between any one of the substrate, the transparent electrode layer and the light emitting layer (including between the substrate and the outside) (for example, JP-A-11-283951).

  These methods can be used in combination with the organic electroluminescence device of the present invention. However, a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter, or a substrate, a transparent electrode layer, and light emission A method of forming a diffraction grating between any of the layers (including between the substrate and the outside) can be suitably used.

  By combining these means, it is possible to obtain an element having higher luminance or durability.

  When a low refractive index medium is formed between the transparent electrode and the transparent substrate with a thickness longer than the wavelength of light, the light extracted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. .

  Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, fluorine polymer, and the like. Since the refractive index of the transparent substrate is generally about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Furthermore, it is preferable that it is 1.35 or less.

  The thickness of the low refractive index medium is preferably at least twice the wavelength in the medium. This is because the effect of the low refractive index layer is diminished when the thickness of the low refractive index medium is about the wavelength of light and the electromagnetic wave that has exuded by evanescent enters the substrate.

  The method of introducing a diffraction grating into an interface or any medium that causes total reflection is characterized by a high effect of improving light extraction efficiency. This method is generated from the light emitting layer by utilizing the property that the diffraction grating can change the direction of light to a specific direction different from refraction by so-called Bragg diffraction such as first-order diffraction or second-order diffraction. Of the light, light that cannot go out due to total reflection between layers, etc., is diffracted by introducing a diffraction grating in any layer or medium (in the transparent substrate or transparent electrode) It tries to take out light.

  The introduced diffraction grating desirably has a two-dimensional periodic refractive index. This is because light emitted from the light-emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating having a periodic refractive index distribution only in a certain direction, only light traveling in a specific direction is diffracted. In other words, the light extraction efficiency does not increase so much. However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and light extraction efficiency is increased.

  As described above, the position where the diffraction grating is introduced may be in any of the layers or in the medium (in the transparent substrate or the transparent electrode), but is preferably in the vicinity of the organic light emitting layer where light is generated.

  At this time, the period of the diffraction grating is preferably about 1/2 to 3 times the wavelength of light in the medium.

  The arrangement of the diffraction gratings is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

<Condensation sheet>
When the organic electroluminescence device of the present invention is used for a surface light source, it is processed so as to provide, for example, a structure on a microlens array on the light extraction side of the substrate, or combined with a so-called condensing sheet. Thus, by focusing light in a specific direction, for example, in the front direction with respect to the element light emitting surface, the luminance in the specific direction can be increased.

  As an example of the microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably 10 μm to 100 μm. If it becomes smaller than this, the effect of diffraction will generate | occur | produce and color, and if too large, thickness will become thick and is not preferable.

  As the condensing sheet, for example, an LED backlight of a liquid crystal display device that is put into practical use can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Ltd. can be used. As the shape of the prism sheet, for example, the base material may be formed with a Δ-shaped stripe having an apex angle of 90 degrees and a pitch of 50 μm, or the apex angle is rounded and the pitch is changed randomly. Other shapes may be used.

  Moreover, in order to control the light emission angle from a light emitting element, you may use a light diffusing plate and a film together with a condensing sheet. For example, a diffusion film “light up” (manufactured by Kimoto Co., Ltd.) can be used.

<Embodiment of Method for Forming Organic EL Layer According to the Present Invention>
Next, an embodiment of a method for forming an organic EL layer according to the present invention will be described with reference to the drawings. The present invention is not limited to the following organic compound layer configuration, and the embodiment is not limited.

  FIG. 1 shows a first embodiment in which an organic EL layer is formed by forming a uniform light emitting layer on the width of a support extended from a roll-shaped support in which a first electrode (anode) is previously formed. FIG. 2 is a schematic diagram showing the form, and FIG. 2 is a schematic diagram showing the layer structure.

  FIG. 3 shows a second embodiment in which an organic EL layer is formed by forming a light emitting layer of a pixel pattern on a support extended from a roll-shaped support in which a first electrode is formed in advance. FIG. 4 is a schematic diagram showing the layer structure.

  The first embodiment and the second embodiment will be described with a focus on the first embodiment, and the second embodiment will be described with respect to parts different from the first embodiment.

  As shown in FIGS. 1 and 3, the organic EL layer is formed by feeding and transporting the support 1 in the direction of the arrow by a driving means (not shown) from a roll-shaped support on which the first electrode is formed in advance. Each transfer process of the surface cleaning modification process 2, the charge removal process 3 at any position, the hole transport layer transfer process 4, the light emitting layer transfer process 5 or 7, and the electron transport layer transfer process 6 is performed in succession. Then, an organic EL layer is formed and wound into a roll.

  In this embodiment, the support 1 uses a polyethylene naphthalate film (a film made by Teijin DuPont, hereinafter abbreviated as PEN) having a thickness of 100 μm, and the PEN is thickened by an atmospheric pressure plasma discharge treatment method. A transparent gas barrier layer having a thickness of about 90 nm is formed, and ITO (indium tin oxide) having a thickness of 120 nm is patterned on the gas barrier layer by vapor deposition to form a first electrode layer. The support, the gas barrier layer, and the first electrode are selected in the above-described << Anode >> on the gas barrier layer formed on the support by the material and method selected in the above-mentioned << Support >>. It is also possible to form the first electrode by the material and method.

  In the surface cleaning / modifying treatment step 2, organic contaminant removal of the support 1 and surface modification for improving wettability are performed. In this embodiment, the dry cleaning apparatus is a low-pressure mercury lamp, but an excimer lamp, a plasma cleaning apparatus, or the like can be used.

  The charge removal processing step 3 is performed on at least one of the upstream side and the downstream side of the support 1 in the transport direction from the transfer position of each transfer step. In this embodiment, it is disposed on the upstream side.

  The charge removal treatment is roughly classified into a light irradiation method and a corona discharge method, in which the light irradiation method generates weak ions and the corona discharge method generates air ions by corona discharge. The air ions are attracted to the charged object to compensate for the opposite polarity charge and neutralize static electricity. Although a static eliminator using corona discharge and a static eliminator using soft X-rays can be used, in this embodiment, a static eliminator using soft X-rays is provided.

  The charge removal treatment removes the charge on the support and prevents adhesion of dust and dielectric breakdown, so that the yield of elements can be improved.

  Next, each transfer process of a positive hole transport layer, a light emitting layer, and an electron carrying layer is demonstrated.

<First embodiment>
As described above, in the first embodiment shown in FIG. 1, the organic EL layer is formed by forming a uniform light emitting layer on the width of the support.

(Hole transport layer transfer process)
In the hole transport layer transfer process, the hole transport layer is formed on the support 1 by transferring the hole transport layer transfer material formed on the endless belt 421 to the support 1.

  The hole transport layer transfer step 4 includes a film forming step of forming a coating film of the hole transport layer transfer material on the endless belt 421 and a step of transferring the hole transport layer transfer material to the support 1. .

  In the film forming step of forming the coating film of the hole transport layer transfer material according to the present embodiment, the coating film is formed on the endless belt 421 by a die coating method to form the hole transport layer transfer material. The endless belt 421 is suspended by a backup roll 422 that is rotationally driven by a driving means (not shown), and is in close contact with and rotates with the backup roll. On the backup roll, a die coater 414 for forming a coating film is installed with a certain gap from the base material of the endless belt 421. Note that a cleaning device may be appropriately attached to the backup roll 422.

  The liquid is sent to the die coater 414 via a filter 413 by controlling the amount of the liquid prepared and stored in the coating liquid tank 411 via a liquid feed pump 412 including a precision pump such as a gear pump. The The supplied liquid is filled in the manifold, and the inside of the chamber is kept at a constant pressure, and the coating liquid is uniformly formed on the endless belt 421 from the coating head through the slit. The thickness of the coating film is appropriately adjusted depending on the substrate conveying speed, the liquid feeding amount, and the solution concentration.

  The conveyance speed unevenness at the time of forming the coating film is preferably 0.2% or more and 10% or less of the average speed with respect to the average coating speed. More preferably, it is 0.2% or more and 3% or less. Thereby, the thickness accuracy in the transport direction of the element is maintained, and the light emission characteristics are made uniform.

  The coating film applied on the endless belt 421 removes the solvent by the drying heat treatment unit 43 using a heated air current, and then heats the back of the endless belt 421 by adding warm air in this embodiment to completely remove the solvent. To remove. By performing the heat treatment, the smoothness of the film, the removal of the residual solvent, and the like can be achieved, thereby improving the element characteristics at the time of stacking. The drying and heating unit 43 can be changed to several zones as appropriate according to the material of the organic compound layer to change the temperature condition or the heating method.

  Through the drying and heating treatment, a hole transport layer transfer material is formed on the endless belt.

  Since an endless belt after the transfer process described below repeatedly forms a transfer coating film, it is preferable to insert a cleaning processing section 44 before the formation. Cleaning can be performed by wet residue cleaning with the same solvent as applied, removing the residue, removing the solvent with an air blower, etc., or dry cleaning using UV ozone cleaning or oxygen plasma cleaning. It is.

  In the transfer process, the coating layer formed on the endless belt 421 is reversed between the endless belt 421 on the backup roll and the heating roll 46 when it is reversed on the backup roll 422 around which the endless belt 421 is suspended. The support 1 is sandwiched between the endless belt, the endless belt, the heating roll, and the support are operated in synchronism to soften the organic compound layer on the endless belt and to transfer it by pressure bonding to the support. The heating roll 46 has a movable structure that allows selection between crimping and non-crimping. The presence / absence of transfer in a plurality of transfer processes can be selected, and the number of transfer layers according to the layer configuration can be selected. The heating roll 46 uses an elastic body, and preferably has a form in which the temperature and the pressure-bonding force can be arbitrarily selected according to the transfer material.

  In the present embodiment, a coating film is formed on the endless belt by a die coat method, which is a continuous wet film forming method. As the continuous wet film forming method, a screen printing method, a flexographic printing method, an ink jet method, and the like are used. Cap coating method, spray coating method, casting method, roll coating method, etc. can be used. These film forming methods can be appropriately selected according to the material of the organic compound layer. In the case of the coating method, it is used when a uniform coating film is formed in the width, and in this case, the endless belt is continuously driven to form the coating film.

  As the material of the endless belt 421, a plastic substrate such as polyethylene, polypropylene, or polyethylene terephthalate, or a metal such as rubber, aluminum, or stainless steel can be used. Of these, stainless steel is preferable in terms of smoothness and durability.

  The endless belt is preferably provided with a release layer made of a suitable oil-repellent material or the like on the endless belt surface in order to efficiently transfer onto the transfer surface and facilitate the peeling of the endless belt surface after image transfer. .

  As such an oil-repellent substance, for example, a silicone resin, a fluororesin, a fluorosurfactant, a polyolefin, a polyamide, or the like can be used. Soluble nylon, partially esterified resin of styrene / maleic anhydride copolymer and methoxymethylated nylon, polyvinyl acetate, polyacrylate, polymethyl methacrylate and acrylate Polymer, polyvinyl chloride, copolymer of vinyl chloride and vinyl acetate, polyvinyl butyrate, cellulose acetate phthalate, methyl cellulose, cellulose triacetate, polyvinyl alcohol, butyl cellulose Hydroxyethyl cellulose, carboxymethyl cellulose, cyanoethyl cellulose, cellulose Asete - DOO, cellulose - Sutoriasete - DOO, cellulose - Suasete - Tobuchire - DOO, hydroxypropyl methyl cellulose - Sufutare - DOO, hydroxypropyl methyl cellulose - to scan Kisahidorofutare - DOO or mixtures thereof and the like can be used.

As a method for providing the release layer on the endless belt, a known method can be used.
For example,
(1) Dissolve the above oil-repellent substance in a solvent, roll coater, gravure coater, reverse roll coater, curtain coater, extrusion coater, slide coater The method of apply | coating using well-known coating devices, such as a taper, is mentioned.
(2) As another method, the above oil-repellent substance is heated to be kept in a molten state, cast onto an endless belt by an extrusion coater, and then subjected to pressure bonding with a metal roller having high smoothness. -The G method is mentioned.

  An anchor layer may be provided at the interface between the endless belt and the release layer for the purpose of enhancing the adhesion between the layers. Examples of the material constituting the anchor layer for enhancing the adhesiveness include known adhesives, such as polyurethane, polyester, isocyanates, and epoxy resins.

  The anchor layer is preferably coated on the transfer belt with the solvent solution before lamination of the release layer, and can be coated using the above-described known coating apparatus.

(Light emitting layer transfer process)
The light emitting layer is formed on the support by transferring the light emitting layer transfer material formed on the endless belt to the support in the same configuration and process as the hole transport layer transfer process.

  In this example, a single color light emitting layer is used. However, by adding a light emitting layer transfer process, a light emitting layer in which a plurality of colors are mixed by stacking a plurality of light emitting layers or using a mixed material of each color light emitting material. Is possible.

(Electron transport layer transfer process)
The electron transport layer is formed on the support by transferring the electron transport layer transfer material formed on the endless belt to the support in the same configuration and process as the hole transport layer transfer process.

  In this embodiment, there are a plurality of transfer steps formed on the endless belt, and the hole transport layer, the light emitting layer, and the electron transport layer are sequentially transferred onto the first electrode in this order with respect to the support. Form.

  The organic compound layer formed by the above process is wound up and stored in a storage box.

  The above process is performed in an atmospheric environment having a dew point temperature of −20 ° C. or lower and a cleanliness class 5 or lower (JISB-9920), and the organic compound layer formation is an environment of 10 ° C. to 45 ° C. excluding the solvent removing step and the heating step. It is desirable that The organic EL layer is weak against moisture and is preferably performed in a dehumidified environment. In addition, the organic EL layer is a very thin film, and if there is a foreign substance, a fault defect occurs, so an environment with a high cleanliness is required. The temperature during film formation is preferably 10 ° C to 45 ° C, more preferably 20 ° C to 25 ° C. If the temperature is low, drying unevenness tends to occur at the time of drying and the coating surface becomes defective. If the temperature is high, a failure defect due to drying of the solution due to solvent evaporation tends to occur at the time of film formation.

The roll taken up by the above process is stored in a storage box and stored under reduced pressure (10 ^{−5 to} 10 Pa). A temperature may be appropriately applied. The storage period is preferably 1 hour to 200 hours, the longer the better. As a result, oxygen and trace moisture due to device deterioration are removed.

  The organic compound layer formed by the above process is formed with an electron injection layer by a vapor deposition method under reduced pressure, and patterned by the vapor deposition method to form a second electrode (cathode). Further, a resin film having a gas barrier property is pressure-bonded and sealed with a sealing adhesive under an inert gas. After sealing and bonding, it is possible to appropriately select a continuous winding and cutting in the next step to form a panel, or a method of cutting continuously without winding and storing in a stocker.

<Second Embodiment>
As described above, in the second embodiment shown in FIG. 3, the organic EL layer is formed by forming the light emitting layer of the pixel pattern on the support.

  Below, it demonstrates centering on a different part from 1st embodiment.

(Hole transport layer transfer process)
This is the same as the hole transport layer transfer step of the first embodiment.

(Light emitting layer transfer process)
The light emitting layer is patterned in a stripe shape to form a coating film. In this embodiment, a coating film of the light emitting layer transfer material is formed using an ink jet coating apparatus.

  The ink jet coating apparatus includes an ink tank 711 for storing ink as a coating liquid, an ink liquid feeding means (not shown) for feeding ink from the ink tank 711 to the ink jet head unit 714, and an ink jet head unit 714 for ejecting ink. The

  The inkjet head unit 714 can move relative to the endless belt 421 in two directions, ie, a conveyance direction (sub-scanning) and a conveyance direction perpendicular (main scanning) by a moving unit (not shown).

  The ink-jet head unit 714 is disposed on a plane transport portion of the endless belt 421 to be transported. The endless belt 421 is intermittently operated, and while the belt is stopped, ink is ejected from the ejection nozzles of the inkjet head unit 714 to form the pixel pattern.

  In this embodiment, as a full color panel application, the red, green and blue light emitting layer solutions are formed and transferred onto one transfer belt with three types of heads. Then, each color may be separately formed and transferred as a transfer film. In this case, a three-color transfer process is required.

  In the transfer process, the coating layer formed on the endless belt 421 is supported between the endless belt on the backup roll and the heating roll 46 when reversed on the backup roll 422 constituting the endless belt. The body 1 is sandwiched and the endless belt, the heating roll, and the support are operated in synchronism to soften the organic compound layer on the endless belt and to transfer it by pressure bonding to the support. The heating roll has a movable structure that can be selected from crimping and non-crimping. The presence or absence of transfer in a plurality of transfer processes can be selected, and the number of transfer layers according to the layer configuration can be selected. The heating roll uses an elastic body, and it is desirable that the temperature and pressure-bonding force can be arbitrarily selected according to the transfer material.

  Regarding the transfer of the patterned light emitting layer, the transfer is performed by the position detecting means of the support and the position detecting means of the endless belt so that the ITO pattern of the first electrode and the transfer pattern of the light emitting layer coincide with each other. The position is determined, and transfer is performed by synchronizing the support and the endless belt.

(Electron transport layer transfer process)
This is the same as the electron transport layer transfer step of the first embodiment.

In this embodiment, there are a plurality of transfer steps formed on the endless belt, and the hole transport layer, the light emitting layer, and the electron transport layer are sequentially transferred onto the first electrode in this order with respect to the support. Formed.
The formed organic compound layer is wound up and stored in a storage box.

  Moreover, the manufacturing environment of the said process is the same as 1st embodiment.

  Subsequent processing is performed in the same manner as in the first embodiment, and an electron injection layer, cathode patterning, and sealing are performed to manufacture a device.

  According to the present invention, even when a plurality of layers are formed, there is no mixing between layers, so that the flexibility of the device configuration is high, the device performance is improved, and efficient and stable production is possible. A method for producing a high organic EL element can be provided.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.
<Example 1>
The organic EL element was manufactured in the first embodiment shown in FIG.
(1) Creation of a strip-shaped flexible support having a gas barrier layer and a first electrode layer in this order.
Using a polyethylene naphthalate film having a thickness of 100 μm (a film made by Teijin DuPont, hereinafter abbreviated as PEN), a gas barrier layer and a first electrode layer are formed in this order on the PEN by the following method. A belt-like flexible support body wound up on a winding core to form a roll was prepared.

(Formation of transparent gas barrier layer)
A transparent gas barrier layer having a thickness of about 90 nm was formed on the prepared PEN by an atmospheric pressure plasma discharge treatment method. It was 10 < ^-3 > g / m < ² > / day or less as a result of measuring water-vapor-permeation rate by the method based on JISK-7129B. The oxygen transmission rate was measured by a method based on JISK-7126B. As a result, it was 10 ⁻³ ml / m ² / day or less.

(Formation of the first electrode layer)
An electrode was formed on the formed barrier layer by vapor deposition of ITO (indium tin oxide) having a thickness of 120 nm, and patterning was performed using photolithography to form a first electrode layer.
(2) Preparation of organic EL layer The above-mentioned roll-shaped support on which the first electrode is formed is continuously subjected to a cleaning surface modification treatment, a charge removal treatment at an arbitrary position, and a transfer, and an organic EL layer. The support on which was formed was wound into a roll. The support conveying speed was 2 m / min.

  Formation of the organic compound layer was performed in an atmospheric environment at a dew point temperature of −20 ° C. or lower and a cleanliness class of 5 or lower (JISB-9920) except for the solvent removal step and the heating step.

(Cleaning surface modification treatment)
As a dry cleaning apparatus, a low pressure mercury lamp wavelength of 184.9 nm, irradiation intensity of 15 mW / cm ² was used, and the distance was 10 mm.

(Charge removal treatment)
In this embodiment, the neutralization with weak X-rays was performed.

(Hole transport layer transfer)
As a hole transport layer, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD) was dissolved in 1,2-dichloroethane to obtain a 0.5 mass% solution. This solution was formed on an endless belt by a die coat method so that the thickness after drying was 50 nm, and a hole transport layer transfer material was provided.

  The endless belt was a stainless steel belt having a thickness of 600 μm.

  After coating, the solvent was removed in a drying heat treatment step using a heated air stream. From the outlet of the drying slit nozzle toward the film forming surface, the air flow was 100 mm in height, the air velocity was 1 m / s, the width distribution was 5%, and the drying temperature was 60 ° C. Then, as an Example, warm air was added to the back surface of the endless belt, the back surface temperature was set to 200 ° C., and the solvent was removed.

  The coating layer formed on the endless belt is sandwiched between the endless belt on the backup roll and the heating roll, and the endless belt, the heating roll and the support are operated in synchronization to endlessly move the coating layer. The organic compound layer on the belt was softened and transferred to the support by pressure bonding to form a hole transport layer on the support.

  After the transfer, the endless belt was dissolved in the same solvent as that applied at the washing processing section to remove the residue, and the solvent was removed with an air blower.

(Light emitting layer transfer)
The light-emitting layer was a green light-emitting layer, and 8% by mass of a dopant material Ir-1 was dissolved in 1,2-dichloroethane in a host material polyvinylcarbazole (PVK) to form a 1% by mass solution. This solution is formed and dried on an endless belt using a die-coat method in the same manner as the hole transport layer transfer so that the thickness after drying is 100 nm, and a light emitting layer transfer material is provided and transferred to a support. Then, a light emitting layer was formed on the support.

(Electron transport layer transfer)
For the electron transport layer, Alq3 was dissolved in 1,2-dichloroethane to obtain a 0.5 mass% solution. This solution is formed and dried on an endless belt in the same manner as the hole transport layer transfer using a die coat method so that the thickness after drying is 50 nm, and an electron transport layer transfer material is provided on the support. Transfer was performed to form an electron transport layer on the support.

As described above, in the present embodiment, the hole transport layer, the light emitting layer, and the electron transport layer are formed in this order on the support in the plurality of transfer steps formed on the endless belt. The organic compound layer was formed by sequentially transferring on one electrode. Then, the said support body was wound up in roll shape and accommodated by the said storage method.
(3) Formation of electron injection layer, cathode, and sealing An electron injection layer and a cathode were formed under reduced pressure on the support on which the organic compound layer was formed.
The support was vapor-deposited with a 0.5 nm thick LiF layer as an electron injection layer under a vacuum of 5 × 10 ⁻⁴ Pa, and subsequently a 100 nm thick aluminum layer was similarly patterned by vapor deposition as a cathode. went.

  Next, the roll-shaped support is fed out under an inert gas, and a UV curable epoxy resin (UV resin XNR5570-B1 manufactured by Nagase Chemtex Co., Ltd.) is removed as a sealing adhesive. An adhesive layer was applied onto the frame by screen printing, and a resin film having a gas barrier property was pressure-bonded and bonded. Then, a UV lamp was applied from the cathode side to bond the resin film.

  The epoxy resin of the adhesive may be a thermosetting type. In that case, thermocompression bonding is performed by passing between the heaters at the time of bonding.

  The element prepared in Example 1 has a light emission of one color, for example, green, but a white organic EL element can be obtained by using a dopant material, a blue material, a red material, and adding a light emitting layer transfer process. Can be created. This can be used as a backlight or a lighting device.

The organic EL device according to Example 1 was caused to emit light, and the uneven emission was visually evaluated. A monochromatic light emitting organic EL element in which no uneven light emission was observed and no characteristic defect due to mixing between layers of the organic EL layer laminated on the support was observed.
<Example 2>
An organic EL element was manufactured in the second embodiment shown in FIG. The following description will focus on differences from the first embodiment. Items not described are in accordance with Example 1.

  The organic compound layer is formed in an atmospheric environment at a temperature of 25 ° C., except for the solvent removal step and the heating step, with a dew point temperature of −20 ° C. or lower and a cleanliness class of 5 or lower (JISB-9920) as in Example 1. It was.

(Formation of the first electrode layer)
On the formed barrier layer, an ITO (indium tin oxide) film having a thickness of 120 nm was formed by vapor deposition, and patterned using a photolitho in stripes with a width of 50 μm and an interval of 30 μm to form a first electrode layer.

(Light emitting layer transfer)
The green light-emitting layer of the light-emitting layer was prepared by dissolving 8% by mass of a dopant material Ir-1 in 1,2-dichloroethane in polyvinyl carbazole (PVK) as a host material. This solution was patterned on an endless belt using an ink jet method so that the thickness after drying was 100 nm and the width was 55 μm.

  Similarly, the red light emitting layer was prepared by dissolving 8% by mass of Ir-9 as a red dopant material in polyvinyl carbazole (PVK) as a host material in 1,2-dichloroethane to form a 1% by mass solution. This solution was patterned on an endless belt using an ink jet method so that the thickness after drying was 100 nm and the width was 55 μm.

  Similarly, the blue light emitting layer was prepared by dissolving 5% by mass of blue dopant Ir-12 in 1,2-dichloroethane in polyvinyl carbazole (PVK) as a host material in a 1% by mass solution. This solution was patterned on an endless belt using an ink jet method so that the thickness after drying was 100 nm and the width was 55 μm.

The three colors were patterned in a line shape at a pitch of 20 μm, and then dried by airflow drying at 60 ° C.
Then, as a present Example, warm air was added to the conveyor back surface, the conveyor back surface temperature was 200 degreeC, and the solvent was removed.

  Regarding the transfer of the patterned light emitting layer, the transfer position is determined by the support position detecting means and the endless belt position detecting means so that the ITO pixel stripe pattern and the light emitting layer transfer pattern coincide with each other. The transfer was performed by synchronizing the support and the endless belt.

The cleaning of the endless belt after the transfer is the same as in Example 1.
(3) Formation of electron injection layer, cathode, and sealing An electron injection layer and a cathode were formed under reduced pressure on the support on which the organic compound layer was formed.
A pixel line is formed by depositing a 0.5 nm thick LiF layer as an electron injection layer under a vacuum of 5 × 10 ⁻⁴ Pa under a vacuum of 5 × 10 ⁻⁴ Pa, and subsequently using a vapor deposition method with a 100 nm thick aluminum layer as a cathode. Patterning was performed in a stripe shape having a width of 200 nm and a spacing of 30 μm in the direction perpendicular to form a second electrode.

  Next, in the same manner as in Example 1, the roll-shaped support was drawn out under an inert gas, and a UV curable epoxy resin (UV resin XNR5570-B1 manufactured by Nagase ChemteX Corporation) was used as a sealing adhesive. Apply an adhesive layer on the frame by screen printing on the part other than the electrode terminal part, and press and bond a gas barrier resin film, and then irradiate the UV lamp from the cathode side to bond the resin film. Carried out.

  The epoxy resin of the adhesive may be a thermosetting type. In that case, thermocompression bonding is performed by passing between the heaters at the time of bonding.

  The element produced in Example 2 can produce a passive matrix full-color organic EL element. This can be used as a display device.

The organic EL element according to Example 2 was caused to emit light, and the uneven emission was visually evaluated. A passive matrix full-color organic EL device in which no light emission unevenness was observed and no characteristic defect due to mixing between layers of the organic EL layer laminated on the support was observed.
<Example 3>
Using the organic EL device manufacturing method of Example 1, the evaluation was performed by changing the environment during the formation of the organic compound layer as shown in Table 1. Moreover, since the coating temperature of the coating liquid for forming an organic compound layer was 25 ° C., the temperature was 25 ° C. in an atmospheric environment except for the solvent removal step and the heating step.

The prepared sample No. The organic EL elements 1 to 7 were caused to emit light, and the presence or absence of a non-light emitting failure was visually evaluated.
Evaluation rank of non-luminous failure ○: Non-luminous failure is not confirmed.

  (Triangle | delta): The slight non-light-emission failure which does not become a problem practically is recognized.

  X: Non-light-emitting failure which is a problem in practice is occasionally observed.

  Table 1 shows the results. In the case of No. 1, depending on the amount of water contained in the sample, the sample No. In the case of 4, it is presumed that a non-light emitting failure has occurred due to the adhered foreign matter. The effectiveness of the present invention was confirmed.

It is a schematic diagram of the formation apparatus which forms a uniform organic electroluminescent layer in the width | variety of the support body which concerns on this invention. It is a schematic diagram which shows the layer structure of the organic electroluminescent layer formed with the formation apparatus shown in FIG. It is a schematic diagram of the formation apparatus which forms the organic electroluminescent layer of a pixel pattern in the support body which concerns on this invention. It is a schematic diagram which shows the layer structure of the organic electroluminescent layer formed with the formation apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 Surface washing | cleaning modification process process 3 Electrostatic removal process process 4 Hole transport layer transfer process 5, 7 Light emitting layer transfer process 6 Electron transport layer transfer process 411,511,611 Coating liquid tank 412,512,612 Delivery liquid Pump 413, 513, 613 Filter
414, 514, 614 Die coater 421 Endless belt 422 Backup roll 43, 53, 63, 73 Drying heat processing unit 44, 54, 64, 74 Cleaning processing unit 46, 56, 66, 76 Heating roll 711 Ink Tank 714 Inkjet head unit

Claims (12)

In the method for forming an organic electroluminescence layer, at least one organic electroluminescence layer comprising at least one organic compound including a light emitting layer on a support is formed by transfer.
The organic compound layer is coated on an endless belt substrate that is driven continuously or intermittently, and then the organic compound layer formed on the endless belt substrate is conveyed in synchronization with the endless belt substrate. A method of forming an organic electroluminescence layer, wherein the transfer is performed on a body. 2. The method of forming an organic electroluminescent layer according to claim 1, wherein the coating of the organic compound is performed by forming a uniform film in a width perpendicular to the conveying direction of the endless belt base material. . The method for forming an organic electroluminescent layer according to claim 1, wherein the coating of the organic compound is performed by an inkjet method. 4. The method for forming an organic electroluminescent layer according to claim 3, wherein the coating performed by the inkjet method is a pattern forming coating of at least one color. The method for forming an organic electroluminescent layer according to any one of claims 1 to 4, further comprising a step of removing the solvent after coating the organic compound on the endless belt base material. 6. The endless belt base material is cleaned after the organic compound layer formed on the endless belt base material is transferred onto the support. 6. A method for forming an organic electroluminescence layer. Static elimination treatment is performed on at least one of the upstream side and the downstream side in the transport direction of the support from the position where the organic compound layer is transferred from the support transported in synchronization with the endless belt base material coated with the organic compound layer. The method for forming an organic electroluminescence layer according to claim 1, wherein the organic electroluminescence layer is formed. 8. The organic electroluminescence layer according to claim 1, wherein the support conveyed in synchronization with the endless belt substrate is cleaned by oxygen plasma or UV irradiation. Method. The organic electroluminescence layer is transferred to a support by the method for forming an organic electroluminescence layer according to any one of claims 1 to 8, and the organic electroluminescence layer is formed. A method for forming an organic electroluminescence layer, wherein the organic electroluminescence layer is wound up into a ru. It is formed under an atmospheric environment having a dew point temperature of -20 ° C or lower and an JISB9920 standard cleanliness class 5 or lower, and an atmospheric condition of 10 ° C or higher and 45 ° C or lower, excluding the drying section. 10. The method for forming an organic electroluminescent layer according to any one of 9 above. It manufactures with the formation method of the organic electroluminescent layer of any one of Claim 1 thru | or 10, The organic electroluminescent element characterized by the above-mentioned. The organic electroluminescence device according to claim 11, wherein the light emission is based on phosphorescence.

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