JP2007005444A - Organic electroluminescent element, its manufacturing method, display device and lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element having high emission efficiency and long luminescence lifetime. <P>SOLUTION: In the organic electroluminescent element, at least one layer of the organic electroluminescent element, having a layer formed by using dispersion solution, comprises cylindrical-shaped molecules. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element, a method for manufacturing the same, a display device, and a lighting device.

  Conventionally, as a light-emitting electronic display device, there is an electroluminescence display (hereinafter referred to as ELD). Examples of constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter referred to as organic EL elements). Inorganic electroluminescent elements have been used as planar light sources, but an alternating high voltage is required to drive the light emitting elements. An organic EL device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and injects electrons and holes into the light emitting layer and recombines them to generate excitons. An element that emits light by using light emission (fluorescence / phosphorescence) when this exciton is deactivated, and can emit light at a voltage of several V to several tens V, and is self-luminous. Therefore, it has a wide viewing angle, high visibility, and since it is a thin-film type complete solid-state device, it has attracted attention from the viewpoints of space saving and portability.

  However, in organic EL elements for practical use in the future, development of organic EL elements that emit light efficiently and with high luminance with lower power consumption is desired.

  In Japanese Patent No. 3,093,796, a stilbene derivative, a distyrylarylene derivative or a tristyrylarylene derivative is doped with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device.

  Further, an element having an organic light-emitting layer in which an 8-hydroxyquinoline aluminum complex is used as a host compound and a small amount of phosphor is doped thereto (for example, JP-A 63-264692), and an 8-hydroxyquinoline aluminum complex is used as a host compound. For example, an element having an organic light emitting layer doped with a quinacridone dye (for example, JP-A-3-255190) is known.

  As described above, when light emission from excited singlet is used, the generation ratio of singlet excitons and triplet excitons is 1: 3, and thus the generation probability of luminescent excited species is 25%. Since the efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.

  However, since Princeton University reported on organic EL devices using phosphorescence emission from excited triplets (MA Baldo et al., Nature, 395, 151-154 (1998)), at room temperature. Research on materials that exhibit phosphorescence has become active.

  For example, M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000), US Pat. No. 6,097,147, and the like.

  When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so that in principle the luminous efficiency is four times that of excited singlets, and there is a possibility that almost the same performance as cold cathode tubes can be obtained. Therefore, it is attracting attention as a lighting application.

  For example, S.M. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001), etc., many compounds have been studied for synthesis centering on heavy metal complexes such as iridium complexes.

  In addition, the aforementioned M.I. A. Baldo et al. , Nature, 403, 17, 750-753 (2000), studies have been made using tris (2-phenylpyridine) iridium as a dopant.

In addition, M.M. E. Thompson et al. In The 10th International Works on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu) used L ₂ Ir (acac) as a dopant, eg (ppy) ₂ Ir (acac), a. 0 g, Tetsuo Tsutsui, etc., again, The 10th International Workshop on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu) in, as a dopant tris (2-(p-tolyl) pyridine) iridium (Ir (ptpy) _3), Studies using tris (benzo [h] quinoline) iridium (Ir (bzq) ₃ ) and the like are being conducted (note that these metal complexes are generally called orthometalated iridium complexes).

  In addition, S. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001), etc., attempts have been made to form devices using various iridium complexes.

  In order to obtain high luminous efficiency, in the 10th International Works on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu), Ikai et al. Uses a hole transporting compound as a host of a phosphorescent compound. In addition, M.M. E. Thompson et al. Use various electron transporting materials as a host of a phosphorescent compound, doped with a novel iridium complex.

  In addition, organic EL elements using these iridium complexes are currently produced mainly by vapor deposition. Research on producing an organic EL element by a coating method has also been actively conducted, but the present situation is that it is difficult to produce an element by a coating method because the solubility of an iridium complex is low. Therefore, it is desired to improve the solubility of the iridium complex.

  Orthometalated complexes in which the central metal is platinum instead of iridium are also attracting attention. With respect to this type of complex, many examples in which a ligand is characterized are known (for example, see Patent Documents 1 to 7).

In any case, bidentate ligands and derivatives thereof, which are mainly bonded to the central metal through two coordination atoms, such as phenylpyridine, have been used as preferred examples of orthometalated complexes. However, the light emission luminance and light emission efficiency when these are used as light emitting elements are greatly improved compared to conventional organic EL elements because the emitted light is derived from phosphorescence. It is known that the lifetime is lower than that of conventional organic EL elements.
JP 2001-181617 A JP 2001-247859 A JP 2002-332291 A JP 2002-332292 A JP 2002-338588 A JP 2002-226495 A JP 2002-234894 A

  This invention is made | formed in view of the subject which concerns, and the objective of this invention is providing the organic EL element with high luminous efficiency and long light emission lifetime.

  The above object of the present invention has been achieved by the following constitution.

(Claim 1)
At least 1 layer of the organic electroluminescent element which has a layer formed using a dispersion liquid contains a rod-shaped molecule | numerator, The organic electroluminescent element characterized by the above-mentioned.

(Claim 2)
An organic electroluminescence device comprising a layer formed using a dispersion containing rod-like molecules.

(Claim 3)
An organic electroluminescence device comprising a layer formed using a dispersion containing a dispersion of rod-like molecules.

(Claim 4)
The organic electroluminescence device according to any one of claims 1 to 3, further comprising a light-emitting layer containing at least a charge transport layer and a phosphorescent complex.

(Claim 5)
The organic electroluminescence device according to claim 4, wherein the charge transport layer contains rod-like molecules.

(Claim 6)
The organic electroluminescence device according to claim 1, wherein the rod-like molecule is a hole transport material.

(Claim 7)
It is white light emission, The organic electroluminescent element of any one of Claims 1-6 characterized by the above-mentioned.

(Claim 8)
In manufacturing the organic electroluminescent element of any one of Claims 1-7, the layer formed using a dispersion liquid is formed into a film by the apply | coating method, The manufacturing method of the organic electroluminescent element characterized by the above-mentioned .

(Claim 9)
The method for producing an organic electroluminescent element according to claim 8, wherein the coating method is an ink jet method.

(Claim 10)
A display device using the organic electroluminescence element according to claim 7.

(Claim 11)
An illuminating device using the organic electroluminescent element according to claim 7.

  According to the present invention, it is possible to provide an organic EL element having high emission efficiency and a long emission lifetime.

  As a result of intensive studies, the present inventor has formed at least one layer of an organic EL element having a layer formed using a dispersion liquid, using an organic EL element containing rod-like molecules and a dispersion containing rod-like molecules. It has been found that an organic EL element having a high emission efficiency and a long emission lifetime can be obtained by an organic EL element having a layer or an organic EL element having a layer formed using a dispersion containing a dispersion of rod-like molecules. It was.

  One of the features of the present invention is to form a layer using rod-like molecules. The rod-shaped molecule has a property of being oriented in a certain direction. For example, when the molecules in the hole transport layer are oriented in a certain direction, carrier mobility is improved and a decrease in driving voltage can be expected. As a result, the lifetime of the organic EL element is expected to be improved.

  Another feature of the present invention is that the layer is formed using a dispersion. If this method is considered as follows, it is presumed that the deterioration of the lifetime of the organic EL can be suppressed. In the usual solution coating method, when the upper layer is applied on the already applied lower layer, the lower layer component is dissolved in the solvent used to dissolve the upper layer component (generally a highly soluble solvent is used). Then, the upper layer and the lower layer are mixed. However, when a dispersion is used for the upper layer coating, it is possible to select a solvent having low solubility, and the lower layer component is less likely to dissolve in the solvent constituting the dispersion during the upper layer coating. It is thought that the mixing ratio of the components can be suppressed. When the upper layer component and the lower layer component are mixed, there is a case where the element lifetime is deteriorated, but it is expected that the deterioration can be improved by a dispersion coating method.

  Hereinafter, the present invention will be described in detail.

[Rod molecule]
In the present invention, a rod-shaped molecule as a target is a rod or a rod whose molecular shape is deformed or deformed in a conformation in which the energy of distortion of chemical bonds constituting the molecule is sufficiently relaxed (for example, linear, banana-shaped, conical-shaped) And the like). The “conformation in which the strain energy of the chemical bond constituting the molecule is sufficiently relaxed” as used herein can be determined by a molecular dynamic calculation that is generally performed for a given molecular structure. The molecular calculation method mentioned here is performed by a general principle such as a molecular orbital (MO) method, a molecular dynamics (MD) method, or a molecular force field (MM) method, or a combination thereof. Either (Ab Initio) calculation or semi-empirical calculation may be used. In the present invention, the rod-like molecules to be subjected to these calculations mean those in a single molecule state in vacuum.

(aspect ratio)
The rod-like molecule of the present invention refers to a molecule having an aspect ratio of 2 or more. Aspect ratio refers to the ratio of the major axis of a molecule to the minor axis of the molecule.

(Compound example)
The rod-like molecule of the present invention is characterized by its shape, and its chemical formula is not limited. In this invention, it is preferable to use for the electric charge transport layer (electron transport layer, hole transport layer) mentioned later. Further, it is preferable to select rod-shaped molecules according to the function of the layer containing rod-shaped molecules. For example, when added to the hole transport layer, the rod-shaped molecules preferably function as a hole transport material. A material functioning as a hole transport material will be described later, and rod-like molecules may be selected from these materials.

  Examples of rod-like molecules that are preferably used in the present invention are shown below.

  These compounds can be synthesized with reference to JP-A No. 2000-281911.

[Dispersion]
The dispersion used in the present invention can be prepared using a method for producing a fine particle dispersion, which is well known as a method for making fine particles. For example, there are dispersion by a physical force using a homogenizer (high pressure, ultrasonic wave, etc.), a bead mill, a jet mill, and an optimizer, and emulsification dispersion. In addition to the above method, in the case of a polymer material, polymer fine particles are synthesized by a method such as gas phase polymerization, emulsion polymerization, suspension polymerization and the like, and this is dispersed in a dispersion (in some cases, redispersion may be necessary). And can be used as the dispersion method of the present invention. Further, these methods may be used in combination. A reprecipitation method has also been reported as a method for preparing nanoparticles (Chemistry and Industry, page 137, 2002). By using this method, it is possible to produce nano-sized direct nanoparticles, which is suitable for obtaining the effects of the present invention.

[Component layer of organic EL element]
The constituent layers of the organic EL element of the present invention will be described. In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.

(I) Anode / light emitting layer / electron transport layer / cathode (ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron Transport layer / cathode (iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole Blocking layer / electron transport layer / cathode buffer layer / cathode Here, the light emitting layer may be a monochromatic light emitting layer having emission maximum wavelengths of 430 to 480 nm, 510 to 550 nm, and 600 to 640 nm, respectively. These light emitting layers may be laminated to form a white light emitting layer, and a non-light emitting intermediate layer may be provided between the light emitting layers. The organic EL device of the present invention is preferably a white light emitting layer.

  Each layer which comprises the organic EL element of this invention is demonstrated.

"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 a photolithography method, or when the pattern accuracy is not required (about 100 μm or more) ), A 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 be 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 to 1000 nm, preferably 10 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 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 with a film thickness of 1-20 nm on a cathode, a 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 reduce drive voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (issued by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).

  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. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  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, aluminum, etc. Metal buffer layer typified by lithium, alkali metal compound buffer layer typified by lithium fluoride, alkaline earth metal compound buffer layer typified by magnesium fluoride, oxide buffer layer typified by aluminum oxide, etc. . 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, it is described in JP-A Nos. 11-204258, 11-204359, and “Organic EL elements and their forefront of industrialization” (issued by NTT, Inc. on November 30, 1998). There is a hole blocking (hole blocking) layer.

  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 concerning this invention as needed.

  The hole blocking layer of the organic EL device of the present invention is preferably provided adjacent to the light emitting layer.

  In the present invention, when a plurality of light emitting layers having different light emission colors are provided, the light emitting layer having the shortest wavelength of light emission is preferably closest to the anode among all the light emitting layers. In this case, it is preferable to additionally provide a hole blocking layer between the shortest wave layer and the light emitting layer next to the anode next to the 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 larger 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.), a 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 the value (eV unit converted value) calculated by performing structural optimization using B3LYP / 6-31G *. 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. For example, a method known as ultraviolet photoelectron spectroscopy can be suitably used by using a low energy electron spectrometer “Model AC-1” manufactured by Riken Keiki Co., Ltd.

  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 thickness of the hole blocking layer and the electron transport layer according to the present invention is preferably 3 to 100 nm, and more preferably 5 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.

  The light emitting layer of the organic EL device of the present invention preferably contains a host compound and a phosphorescent light emitting complex.

(Host compound)
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 the phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) It is defined as a compound of less than 0.1. The phosphorescence quantum yield is preferably less than 0.01.

  In the present invention, a carbazole derivative or an azacarbazole derivative is preferred as the host compound, but it may be a known host compound or may be used in combination.

  Specific examples of the carbazole derivative useful as a host compound used in the light emitting layer of the organic EL device of the present invention will be given. However, the present invention is not limited to these.

  Further, specific examples of azacarbazole derivatives useful as host compounds used in the light emitting layer of the organic EL device of the present invention will be given. However, the present invention is not limited to these.

  Further, a plurality of known host compounds may be used in combination. 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. Moreover, it becomes possible to mix different light emission by using multiple types of phosphorescence emission complexes, and, thereby, arbitrary luminescent colors can be obtained. White light emission is possible by adjusting the kind of phosphorescent complex and the amount of doping, and can also be applied to illumination and backlight.

  As the known host compound that may be used in combination, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from becoming longer, and has a high Tg (glass transition temperature) is preferable.

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

  JP 2001-257076 A, JP 2002-308855 A, JP 2001-313179 A, 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, when having a plurality of light-emitting layers, 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 more preferable that the phosphorescence emission energy of the compound is 2.9 eV or more because it is advantageous in efficiently suppressing energy transfer from the dopant and obtaining high luminance.

  The phosphorescence emission energy as used in the field of this invention means the peak energy of the 0-0 band of the phosphorescence emission which measures the photoluminescence of a 100 nm vapor deposition film | membrane on a board | substrate with a host compound.

  The host compound used in the present invention preferably has a phosphorescence energy of 2.9 eV or more and a Tg of 90 ° C. or more. If the Tg is lower than 90 ° C., the deterioration of the element over time (decrease in luminance, deterioration of film properties) is large and the market needs as a light source cannot be satisfied. That is, in order to satisfy both luminance and durability, it is preferable that phosphorescence emission energy is 2.9 eV or more and Tg is 90 ° C. or more. Tg is more preferably 100 ° C. or higher.

  In the present invention, in the case of having a plurality of light emitting layers, 50% by mass or more of the host compound of the light emitting layer is the same compound having a phosphorescence emission energy of 2.9 eV or more and Tg of 90 ° C. or more. preferable. Surprisingly, even if the Tg is 90 ° C or higher and the material is individually excellent in durability, when a different compound is used for each light emitting layer, the same compound is used for all the light emitting layers in terms of the storage characteristics of the entire device. It was found that there was a case where it deteriorated compared with the case where it was. Although the cause of this is not clearly understood, when 50% by mass or more of the host compounds in all the light emitting layers are the same, that is, when the host compounds in all the light emitting layers are substantially the same, uniform film surface properties are obtained. Although it is easy to obtain, when a different compound is used for each light emitting layer, each compound is stable, but non-uniformity is likely to occur at the layer interface or the like.

(Phosphorescent complex)
The material used for the light emitting layer (hereinafter referred to as the light emitting material) contains the above-mentioned host compound and simultaneously contains a phosphorescent compound. Thereby, solution application property improves and it can be set as an organic EL element with higher luminous efficiency.

  The phosphorescent complex 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 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 the Fourth Edition Experimental Chemistry Course 7. Although the phosphorescence quantum yield in a solution can be measured using various solvents, the phosphorescence emission complex used for this invention should just achieve the said phosphorescence quantum yield in any solvent.

  There are two types of light emission of the phosphorescent complex, 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. The energy transfer type, in which light emission from the phosphorescent complex is obtained by transferring to the phosphorescent complex. It is a carrier trap type in which light emission from the photoluminescent complex can be obtained, but in any case, it is a condition that the excited state energy of the phosphorescent complex is lower than the excited state energy of the host compound. .

  Below, a specific example is given about an iridium complex among the phosphorescence emission complexes preferably used for the organic EL element of this invention. However, the present invention is not limited to these.

  In the present invention, in addition to a phosphorescent complex, a complex compound containing a group 8-10 metal in the periodic table of elements, preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex compound), a rare earth complex May be used in combination.

  These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent complex is not particularly limited, and can be obtained in principle by selecting a central metal, a ligand, a ligand substituent, and the like. The emitted light 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 when the front luminance at 2 ° C. viewing angle is measured by the above method, the chromaticity in the CIE 1931 color system at 1000 Cd / m ² is X = 0.33 ± 0.07, It is in the region of Y = 0.33 ± 0.07.

  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, or an ink jet method.

  In the present invention, the light emitting layer includes layers having different emission spectra in which the emission maximum wavelengths are in the range of 430 to 480 nm, 510 to 550 nm, and 600 to 640 nm, or a layer in which these are laminated.

  There is no restriction | limiting in particular as a lamination order of a light emitting layer, You may have a nonluminous intermediate | middle layer between each light emitting layer. In the present invention, it is preferable that at least one blue light emitting layer is provided at a position closest to the anode in all the light emitting layers.

  When four or more light-emitting layers are provided, for example, blue / green / red / blue, blue / green / red / blue / green, blue / green / red / blue / green / red from the order close to the anode. In order to improve luminance stability, it is preferable to sequentially stack blue, green, and red.

  The total film thickness of the light emitting layer is not particularly limited, but is usually 2 nm to 5 μm, preferably 2 to 200 nm. In the present invention, it is preferably in the range of 10 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 thickness of each light emitting layer is preferably selected in the range of 2 to 100 nm, and more preferably in the range of 2 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 to 480 nm and a green light emitting compound having the same wavelength of 510 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. In the present invention, the rod-like molecule is preferably a hole transport material. Specific compounds include, for example, triazole derivatives, oxadiazole 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) quadriphenyl; 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, as well as two of those described in US Pat. No. 5,061,569 Having a condensed aromatic ring in the molecule, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

  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. It is also possible to use so-called p-type hole transport materials as described in the literature (Applied Physics Letters 80 (2002), p. 139). 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 can be 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. it can. 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 5-200 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 a 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.

  In the present invention, it is preferable to use a hole transport layer having such a high p property because a device with lower power consumption can be produced.

《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 Thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives and the like. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. 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, 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), and the like, and the central metals of these metal complexes are In, Mg, Metal complexes replaced with 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 transporting 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.

  In the present invention, rod-like molecules are preferably used for the electron transport layer.

  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 5-200 nm. The electron transport layer may have a single layer structure composed of one or more of the above materials.

  Further, an electron transport layer having a high n property doped with impurities can also 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.

  In the present invention, it is preferable to use an electron transport layer having such a high n property because an element with lower power consumption can be manufactured.

《Support substrate》
The support substrate (hereinafter also referred to as a substrate, substrate, substrate, support, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the type of glass, plastic, etc., and is transparent. Or opaque. When extracting light from the support substrate side, the support substrate is preferably transparent. Examples of the transparent support substrate preferably used include glass, quartz, and a transparent resin film. A particularly preferable support substrate 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, cellulose triacetate, cellulose acetate butyrate, cellulose acetate propionate (CAP), Cellulose esters such as 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 Cycloolefin resins such as polyetherimide, polyetherketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic or polyarylate, Arton (trade name, manufactured by JSR) or Appel (trade name, manufactured by Mitsui Chemicals) Can be mentioned. The surface of the resin film may be formed with an inorganic film, an organic film, or a hybrid film of both, and 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 g / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less is preferable.

  The material for forming the barrier film may be any material as long as it has a function of suppressing intrusion of elements that cause deterioration of elements such as moisture and oxygen. 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 organic material layers. 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, vacuum deposition, sputtering, reactive sputtering, molecular beam epitaxy, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma A 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 polymerization method as described in JP-A-2004-68143 is particularly preferable.

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

  The external extraction efficiency at room temperature of light emission of the organic EL device of the present invention is preferably 1% or more, more preferably 5% or more. Here, the external extraction quantum efficiency (%) = the number of photons emitted to the outside of the organic EL element / the number of electrons sent to the organic EL element × 100.

  In addition, a hue improvement filter such as a color filter may be used in combination, or a color conversion filter that converts the emission color from the organic EL element into multiple colors using a phosphor. In the case of using a color conversion filter, the λmax of light emission of the organic EL element is preferably 480 nm or less.

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

  The sealing member may be disposed so as to cover the display area of the organic EL element, and may be concave or flat. 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, and polysulfone. 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 element can be thinned. Furthermore, the polymer film preferably has an oxygen permeability of 10 ⁻³ g / m ² / day or less and a water vapor permeability of 10 ⁻⁵ g / m ² / day or less.

  For processing the sealing member into a concave shape, sandblasting, chemical etching, or the like is used.

  Specific examples of the adhesive include photocuring and thermosetting adhesives having reactive vinyl groups such as acrylic acid oligomers and methacrylic acid oligomers, and moisture curing adhesives such as 2-cyanoacrylates. be able to. Moreover, 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 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 substrate with the organic layer interposed therebetween, and form an inorganic or organic layer in contact with the support substrate 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 elements such as moisture and oxygen. For example, silicon oxide, silicon dioxide, silicon nitride, or the like may be used. it can. Further, 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 method, ion plating method, plasma polymerization method, atmospheric pressure plasma A 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 preferred. 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, Magnesium chlorate, etc.), and anhydrous salts are preferably used in sulfates, metal halides and perchloric acids.

《Protective film, protective plate》
In order to increase the mechanical strength of the element, a protective film or a protective plate may be provided outside the sealing film or the sealing film on the side facing the support substrate with the organic layer interposed therebetween. In particular, when sealing is performed by the sealing film, the mechanical strength is not necessarily high, and thus it is preferable to provide such a protective film and a protective plate. As a material that can be used for this, the same glass plate, polymer plate / film, metal plate / film, etc. used for the sealing can be used, but the polymer film is light and thin. Is preferably used.

《Light extraction》
The organic EL element emits light within a layer having a refractive index higher than that of air (refractive index is about 1.7 to 2.1), and can extract only about 15% to 20% of the light generated in the light emitting layer. It is generally said that there is no. 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 method 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 transparent substrate and the air interface (US Pat. No. 4,774,435), A method of improving efficiency by providing light condensing property (Japanese Patent Laid-Open No. 63-314795), a method of forming a reflective surface on the side surface of the element (Japanese Patent Laid-Open No. 1-220394), and between the substrate and the light emitter A method of introducing an antireflection film by introducing a flat layer having an intermediate refractive index (Japanese Patent Laid-Open No. 62-172691), and a method of introducing a flat layer having a lower refractive index than the substrate between the substrate and the light emitter. (Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any one of a substrate, a transparent electrode layer, and a light emitting layer (including between the substrate and the outside) (Japanese Patent Laid-Open No. 11-283751).

  In the present invention, these methods can be used in combination with the organic EL 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, transparent A method of forming a diffraction grating between any layers of the electrode layer and the light emitting layer (including between the substrate and the outside) can be suitably used.

  In the present invention, 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, and a fluorine-based polymer. 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. 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 grating is preferably two-dimensionally repeated, such as a square lattice, a triangular lattice, or a honeycomb lattice.

《Condensing sheet》
The organic EL device of the present invention is processed to provide, for example, a microlens array-like structure on the light extraction side of the substrate, or is combined with a so-called condensing sheet, for example, with respect to a specific direction, for example, the light emitting surface By condensing in the front direction, the luminance in a 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, a sheet that is put into practical use in an LED backlight of a liquid crystal display device can be used. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, a substrate 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 together a light diffusing plate and a film with a condensing sheet. For example, a diffusion film (light-up) manufactured by Kimoto Co., Ltd. can be used.

<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

  First, a thin film made of a desired electrode material, for example, a material for an anode is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably 10 to 200 nm to produce an anode. .

  Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are organic EL element materials, is formed thereon.

  As a method for thinning the organic compound thin film, there are a vapor deposition method and a wet process (spin coating method, casting method, ink jet method, printing method) as described above, but it is easy to obtain a uniform film and a pinhole. In the present invention, film formation by a coating method such as a spin coating method, an ink jet method, or a printing method is particularly preferable.

  In the present invention, in the formation of the light emitting layer, it is preferable to form a film by a coating method using a solution in which a phosphorescent complex is dissolved or dispersed, and the coating method is particularly preferably an ink jet method.

  Examples of the liquid medium for dissolving or dispersing the phosphorescent complex include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, and organic solvents such as DMF and DMSO. Can be used. Moreover, as a dispersion method, it can disperse | distribute by dispersion methods, such as an ultrasonic wave, high shear force dispersion | distribution, and media dispersion | distribution.

  After forming these layers, a thin film made of a cathode material is formed thereon by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and a cathode is provided. Thus, a desired organic EL element can be obtained.

  In addition, it is also possible to reverse the production order and produce the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the hole transport layer, the hole injection layer, and the anode in this order. When a DC voltage is applied to the multicolor display device thus obtained, light emission can be observed by applying a voltage of about 2 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. An alternating voltage may be applied. The alternating current waveform to be applied may be arbitrary.

<Application>
The organic EL element of the present invention can be used as a display device, a display, and various light emission sources. Examples of light sources include home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources for optical sensors. However, the present invention is not limited to this, but it can be effectively used particularly as a backlight of a liquid crystal display device and a light source for illumination.

  In the organic EL element concerning this invention, you may pattern by a metal mask, an inkjet printing method, etc. at the time of film forming as needed. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. Unless otherwise specified, “%” in the examples represents “mass%”.

Example 1
<< Production of Organic EL Element 1-1 >>
After patterning on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) having a film of 150 nm of ITO (indium tin oxide) formed on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode, this ITO transparent electrode was provided. The transparent support substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

  A coating solution of α-NPD (compound 1-1) (a solution of 3 ml of compound 1-1 (10 mg) dissolved in dichlorobenzene) was spin-coated at 500 rpm for 30 seconds on this transparent support substrate, and a hole with a thickness of 45 nm was formed. A transport layer was provided.

Subsequently, this transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus, 200 mg of CBP is put into a molybdenum resistance heating boat, and 200 mg of bathocuproine (BCP) is put into another resistance heating boat made of molybdenum. 100 mg of Illustrated Compound Ir-1 (phosphorescent compound) was placed in a molybdenum resistance heating boat, and 200 mg of Alq ₃ was placed in another molybdenum resistance heating boat, which was attached to a vacuum deposition apparatus. Next, after reducing the vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating boat containing CBP as the host compound and Ir-1 as the dopant compound was energized and heated to 220 ° C., and the deposition rate was set to 0. A light-emitting layer having a thickness of 20 nm was provided by co-evaporation on the hole transport layer at 1 nm / sec and 0.01 nm / sec. In addition, the substrate temperature at the time of vapor deposition was room temperature. Furthermore, the electron transport which also served as the hole blocking | prevention of the film thickness of 10 nm by energizing the said heating boat containing BCP, heating up to 250 degreeC, and vapor-depositing on the said light emitting layer with a vapor deposition rate of 0.1 nm / sec. A layer was provided. In addition, the heating boat containing Alq ₃ is further energized and heated to 250 ° C., and deposited on the electron transport layer at a deposition rate of 0.1 nm / sec. Was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature.

Next, the vacuum chamber was opened and a stainless steel rectangular perforated mask was placed on the electron transport layer, while 3 g of magnesium was placed in a molybdenum resistance heating boat, and 0.02 of silver was placed in a tungsten vapor deposition basket. After putting 5 g and depressurizing the vacuum tank to 2 × 10 ⁻⁴ Pa again, energizing the boat containing magnesium to deposit magnesium at a deposition rate of 1.5 to 2.0 nm / sec. The organic EL element 1-1 (comparative example) was produced by heating silver and depositing silver at a deposition rate of 0.1 nm / sec to form a counter electrode made of the mixture of magnesium and silver.

<< Production of Organic EL Element 1-2 >>
In the production of the organic EL element 1-1, an organic EL element 1-2 was produced in the same manner except that the α-NPD coating liquid for the hole transport layer was changed to the following dispersion liquid.

(Preparation of dispersion)
α-NPD (50 g) was added to 300 ml of ethyl alcohol, and this was dispersed with an apex mill manufactured by Sakai Kogyo at a peripheral speed of 8 m / sec using 0.05 mm beads to obtain a desired fine particle alcohol dispersion ( (Average particle size 35 nm).

<< Production of Organic EL Elements 1-3 to 1-5 >>
Organic EL elements 1-3 to 1-5 were prepared in the same manner as in the preparation of the organic EL element 1-2, except that α-NPD in the dispersion was changed to each compound shown in Table 1.

  The structure of the compound used above is shown below.

<< Evaluation of organic EL elements >>
Using the ITO electrode of each of these organic EL elements as an anode, a counter electrode made of magnesium and silver, continuous lighting is performed by applying a DC voltage of 10 V in a dry nitrogen gas atmosphere at 23 ° C., and the luminance is halved from the emission luminance at the start of lighting. The time (hereinafter referred to as the light emission lifetime) and the light emission efficiency (lumen / W) were measured, and the results are shown in Table 1. However, the light emission lifetime and the light emission efficiency were expressed as relative values with the light emission lifetime and the light emission efficiency of the organic EL element 1-1 being 100. The emission luminance was measured using Minolta CS-1000.

  As is clear from Table 1, the organic EL device according to the present invention was found to be very useful as an organic EL device because of its high luminous efficiency and long emission lifetime.

Example 2
<< Production of organic EL full-color display device >>
FIG. 1 shows a schematic configuration diagram of an organic EL full-color display device. After patterning at a pitch of 100 μm on a substrate (NH45 manufactured by NH Techno Glass Co., Ltd.) formed by forming a 100 nm ITO transparent electrode (102) on a glass substrate 101 as an anode, non-between the ITO transparent electrodes on this glass substrate. A photosensitive polyimide partition 103 (width 20 μm, thickness 2.0 μm) was formed by photolithography. A hole injection layer composition having the following composition is ejected and injected between polyimide partition walls on the ITO electrode using an inkjet head (manufactured by Epson Corporation; MJ800C), and a hole having a film thickness of 40 nm is obtained by drying at 200 ° C. for 10 minutes. An injection layer 104 was produced. A hole transport layer composition, a blue light-emitting layer composition, a green light-emitting layer composition, and a red light-emitting layer composition prepared by the methods described below are similarly ejected and injected onto the hole injection layer using an inkjet head. Then, the hole transport layer and the respective light emitting layers (105B, 105G, 105R) were formed. Finally, Al (106) was vacuum-deposited as a cathode so as to cover the light emitting layer 105, and an organic EL element was produced.

(Hole injection layer composition)
PEDOT / PSS mixed water dispersion (1.0% by mass) 20 parts by mass Water 65 parts by mass Ethoxyethanol 10 parts by mass Glycerin 5 parts by mass PEDOT / PSS: Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (Bayer) Baytron P Al 4083)
(Hole transport layer composition)
α-NPD (50 g) was added to 300 ml of ethyl alcohol, and this was dispersed with an apex mill manufactured by Sakai Kogyo at a peripheral speed of 8 m / sec using 0.05 mm beads to obtain a desired fine particle alcohol dispersion ( (Average particle size 35 nm).

(Blue light emitting layer composition)
PVK 0.7 parts by mass Ir-12 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass (green light emitting layer composition)
PVK 0.7 parts by mass Ir-1 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass (red light emitting layer composition)
PVK 0.7 parts by mass Ir-9 0.04 parts by mass Cyclohexylbenzene 50 parts by mass Isopropyl biphenyl 50 parts by mass The produced organic EL elements exhibit blue, green and red light emission by applying voltage to the respective electrodes. It was found that it can be used as a full-color display device.

Example 3
<< Preparation of a lighting device using a white organic EL element >>
In the organic EL element 1-2 produced in Example 1, the same as the organic EL element 2-1, except that Ir-1 used in the light emitting layer was changed to a mixture of Ir-12, Ir-1, and Ir-9 The organic EL element 2-1W was produced by the method. When a 10 V DC voltage was applied to the organic EL element 2-1W, almost white light emission was obtained.

It is a schematic block diagram of an organic EL full-color display device.

Explanation of symbols

101 Glass substrate 102 ITO transparent electrode 103 Partition 104 Hole injection layer 105B, 105G, 105R Light emitting layer

Claims (11)

At least 1 layer of the organic electroluminescent element which has a layer formed using a dispersion liquid contains a rod-shaped molecule | numerator, The organic electroluminescent element characterized by the above-mentioned. An organic electroluminescence device comprising a layer formed using a dispersion containing rod-like molecules. An organic electroluminescence device comprising a layer formed using a dispersion containing a dispersion of rod-like molecules. The organic electroluminescence device according to any one of claims 1 to 3, further comprising a light-emitting layer containing at least a charge transport layer and a phosphorescent complex. The organic electroluminescence device according to claim 4, wherein the charge transport layer contains rod-like molecules. The organic electroluminescence device according to claim 1, wherein the rod-like molecule is a hole transport material. It is white light emission, The organic electroluminescent element of any one of Claims 1-6 characterized by the above-mentioned. In manufacturing the organic electroluminescent element of any one of Claims 1-7, the layer formed using a dispersion liquid is formed into a film by the apply | coating method, The manufacturing method of the organic electroluminescent element characterized by the above-mentioned . The method for producing an organic electroluminescent element according to claim 8, wherein the coating method is an ink jet method. A display device using the organic electroluminescence element according to claim 7. An illuminating device using the organic electroluminescent element according to claim 7.

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