JP4899284B2 - Organic electroluminescence element, lighting device and display device - Google Patents

Organic electroluminescence element, lighting device and display device Download PDF

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JP4899284B2
JP4899284B2 JP2003199073A JP2003199073A JP4899284B2 JP 4899284 B2 JP4899284 B2 JP 4899284B2 JP 2003199073 A JP2003199073 A JP 2003199073A JP 2003199073 A JP2003199073 A JP 2003199073A JP 4899284 B2 JP4899284 B2 JP 4899284B2
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light emitting
layer
organic el
emitting layer
compound
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JP2005038672A (en
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安紀 中田
弘志 北
善幸 硯里
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コニカミノルタホールディングス株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescence element, an illumination device, and a display device, and more particularly to an organic electroluminescence element, an illumination device, and a display device that have a long lifetime.
[0002]
[Prior art]
Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of constituent elements of ELD include inorganic electroluminescent elements and organic electroluminescent elements (hereinafter also 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.
[0003]
On the other hand, an organic electroluminescence 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 excitons (excitons) by injecting electrons and holes into the light emitting layer and recombining them. Is a device that emits light using the emission of light (fluorescence / phosphorescence) when this exciton is deactivated, and can emit light at a voltage of several volts to several tens of volts. Since it is a mold, it has a wide viewing angle, has high visibility, and is a thin-film complete solid-state device, and therefore has attracted attention from the viewpoints of space saving, portability, and the like.
[0004]
For the development of organic EL elements for practical use in the future, organic EL elements that emit light efficiently and with high brightness with lower power consumption are desired. For example, stilbene derivatives, distyrylarylene derivatives, or tris A technique for doping a styrylarylene derivative with a small amount of a phosphor to improve emission luminance and extend the lifetime of the device (see, for example, Patent Document 1), and using 8-hydroxyquinoline aluminum complex as a host compound, An organic light emitting layer having an organic light emitting layer doped with a small amount of a phosphor (see, for example, Patent Document 2), further comprising an 8-hydroxyquinoline aluminum complex as a host compound and doped with a quinacridone dye. There is a report on an element having the above (for example, see Patent Document 3).
[0005]
In the technique disclosed in the above document, when the emission from the excited singlet is used, the generation ratio of the singlet exciton and the triplet exciton is 1: 3, so the generation probability of the luminescent excited species is 25%. Since the light extraction efficiency is about 20%, the limit of the external extraction quantum efficiency (ηext) is set to 5%.
[0006]
However, since the University of Princeton reported on organic EL devices using phosphorescence emission from excited triplets (see, for example, Non-Patent Document 1), research on materials that exhibit phosphorescence at room temperature (for example, Non-Patent Documents). 2, see Patent Document 4).
[0007]
When excited triplets are used, the upper limit of internal quantum efficiency is 100%, so in principle the luminous efficiency is four times that of excited singlets, and the performance is almost the same as that of cold cathode tubes. It can be applied to and is attracting attention.
[0008]
The 10th International Workshop on Inorganic and Organic Electroluminescence (EL'00, Hamamatsu) reports several reports on phosphorescent compounds. For example, 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 transport materials doped with a novel iridium complex as a host of a phosphorescent compound. Furthermore, Tsutsui et al. Have obtained high emission luminance by introducing a hole blocking layer (exciton blocking layer). As the hole blocking layer, other examples using a 5-coordinate aluminum complex (for example, refer to Patent Documents 5 and 6), examples using a biscarbazole derivative (for example, refer to Patent Document 7), and Ikai et al. By using a fluorine-substituted compound as the hole block layer (exciton block layer), highly efficient light emission is achieved (for example, see Non-Patent Document 3).
[0009]
[Patent Document 1]
Japanese Patent No. 3093796
[0010]
[Patent Document 2]
Japanese Unexamined Patent Publication No. 63-264692
[0011]
[Patent Document 3]
JP-A-3-255190
[0012]
[Patent Document 4]
JP 2000-21572 A
[0013]
[Patent Document 5]
JP 2001-284056 A
[0014]
[Patent Document 6]
Japanese Patent Laid-Open No. 2002-8860
[0015]
[Patent Document 7]
JP 2003-31371 A
[0016]
[Non-Patent Document 1]
M.M. A. Baldo et al. , Nature, 395,
151-154 pages (1998)
[0017]
[Non-Patent Document 2]
M.M. A. Baldo et al. , Nature, volume 403,
17, 750-753 pages (2000)
[0018]
[Non-Patent Document 3]
Appl. Phys. Lett. 79 volumes
156 pages (2001)
[0019]
[Problems to be solved by the invention]
The organic EL element is known to improve the light emission efficiency by confining carriers in the light emitting layer. For example, when the light emitting material has a hole transporting property, the hole blocking layer adjacent to the light emitting layer, electron transport Holes flow out to the layer, and the hole blocking layer and the electron transport layer are deteriorated by the flowed out holes, and the lifetime of the organic EL element is decreased. Similarly, when the light-emitting material has an electron transporting property, electrons flow out from the light-emitting layer to the adjacent electron blocking layer and hole transporting layer, and the electron blocking layer and hole transporting layer deteriorate due to the flowing out electrons, The lifetime of the organic EL element is reduced. In addition, the organic EL element is required to have higher luminous efficiency.
[0020]
This invention is made | formed in view of the subject which concerns, and the objective of this invention is providing the organic electroluminescent element, the illuminating device, and the display apparatus which are long life.
[0021]
Another object of the present invention is to provide an organic electroluminescence element, a lighting device, and a display device having high luminous efficiency.
[0022]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following constitution.
[0023]
  (1) In an organic electroluminescence device having a light emitting layer containing a light emitting material between a cathode and an anode, at least one layer of the light emitting layer contains a host compound and a hole transporting dopant composed of a phosphorescent compound, And the average content (mass%) of the hole transportable dopant which consists of the said phosphorescent compound in the 30 volume% area | region of the cathode side in this light emitting layer is A, and the remaining 70 except the area | region of the said cathode side 30 volume%. An organic electroluminescence device satisfying the following formula (1 ′), where B is an average content (% by mass) of a hole transporting dopant made of the phosphorescent compound in a volume% region.
          0.2 <A / B <0.5 (1 ′)
However, the case where the host compound is the following anthracene dinaphthyl (ADN) and the hole transporting dopant is a distyrylamine derivative (DSA derivative) is excluded.
[Chemical A]
  (2)2. The organic electroluminescence device according to item 1, wherein the hole transporting dopant comprises a combination of two or more phosphorescent compounds.
  (3) No.A display device comprising the organic electroluminescence element according to item 1 or 2.
  (4) No.An illuminating device comprising the organic electroluminescence element according to item 1 or 2.
  (5)A display device comprising: the lighting device according to item 4; and a liquid crystal element as display means.
[0035]
Hereinafter, the present invention will be described in detail.
As a result of intensive studies, the present inventors have found that in an organic electroluminescence device having at least a light emitting layer containing a light emitting material between a cathode and an anode, the light emitting material is a hole transporting dopant, and By reducing the average content of the hole-transporting dopant of 30% by volume on the cathode side from the average content of the remaining 70% by volume of the hole-transporting dopant in the light-emitting layer, the outflow of holes from the light-emitting layer is suppressed. The present inventors have found that the lifetime of the organic EL element can be extended by suppressing the deterioration of the layer adjacent to the light emitting layer on the cathode side.
[0036]
That is, when a hole transporting dopant is used as the light emitting material, the average content of the hole transporting dopant of 30% by volume of the cathode side of the light emitting layer is the average of the remaining 70% by volume of the hole transporting dopant of the light emitting layer. By keeping the content lower than the content rate, it is possible to suppress the concentration of holes on the cathode side of the light emitting layer, and thereby the layer adjacent to the light emitting layer on the cathode side (for example, hole blocking layer, electron transport layer, etc. It has been found that the hole can be prevented from flowing out to prevent deterioration and extend the life of the organic EL device.
[0037]
In the present invention, when the average content of 30% by volume of the hole transporting dopant on the cathode side of the light emitting layer is A and the average content of the remaining 70% by volume of the hole transporting dopant is B, the following formula ( It is preferable to satisfy 1).
[0038]
0.1 <A / B <0.8 (1)
Thereby, the outflow of holes from the light emitting layer can be further suppressed, and the life of the organic EL element can be extended. In particular, it is more preferable to satisfy 0.2 <A / B <0.5 in order to further obtain the effects of the present invention.
[0039]
Further, as a result of intensive studies, the present inventors have found that in an organic electroluminescence device having at least a light emitting layer containing a light emitting material between a cathode and an anode, the light emitting material is an electron transporting dopant, and the light emitting layer By reducing the average content of the electron transporting dopant of 30% by volume on the anode side from the average content of the remaining 70% by volume of the electron transporting dopant in the light emitting layer, the outflow of holes from the light emitting layer is suppressed, It has been found that the lifetime of the organic EL element can be extended by suppressing deterioration of the layer adjacent to the light emitting layer on the anode side.
[0040]
That is, when an electron transporting dopant is used as the light emitting material, the average content of the electron transporting dopant on the anode side of the light emitting layer is 30% by volume from the average content of the remaining 70% by volume of the electron transporting dopant on the light emitting layer. By reducing the amount, electrons are prevented from concentrating on the anode side of the light emitting layer, and thereby, electrons flow out to the layers adjacent to the light emitting layer on the anode side (electron blocking layer, hole transport layer, etc.). It was found that the lifetime of the organic EL element can be extended by suppressing the deterioration.
[0041]
In the present invention, when the average content of 30% by volume of the hole transporting dopant on the cathode side of the light emitting layer is A and the average content of the remaining 70% by volume of the hole transporting dopant is B, the following formula ( It is preferable to satisfy 2).
[0042]
0.1 <A / B <0.8 (2)
Thereby, the outflow of holes from the light emitting layer can be further suppressed, and the life of the organic EL element can be extended. In particular, it is more preferable to satisfy 0.2 <A / B <0.5 in order to further obtain the effects of the present invention.
[0043]
In the present invention, the hole-transporting dopant is a dopant whose hole mobility is higher than the electron mobility, and the electron-transporting dopant is a dopant whose electron mobility is higher than the hole mobility. It is.
[0044]
Hole mobility and electron mobility are measured by the time of flight (TOF) method as follows. For example, Optel TOF-301 can be used for the measurement. A thin film in which 10% of a luminescent dopant is dispersed in an electrochemically inactive polymer is sandwiched between an ITO translucent electrode and a metal electrode. The hole mobility and the electron mobility are obtained from the transient current characteristics of the sheet-like carrier generated by the pulse wave irradiated from the side. As the electrochemically inactive polymer, for example, polycarbonate or polystyrene can be used.
In the present invention, 30% by volume of the cathode side of the light emitting layer and the remaining 70% by volume are the region of 30% by volume close to the cathode side and the other 70% by volume of the light emitting layer between the cathode and the anode. I point to.
[0045]
As shown in FIG. 1, a normal organic EL element has a uniform thickness between a cathode and an anode on a plane and a light emitting layer and other layers (a blocking layer, a transport layer, a buffer layer, etc., which will be described later). It is formed as a layer having. Therefore, if the thickness of the light emitting layer is d, the region of the light emitting layer whose distance from the cathode side light emitting layer interface is 0.3d corresponds to 30% by volume of the cathode side of the light emitting layer, and the remaining 70% by volume is the anode volume. This corresponds to the region of the light emitting layer whose distance from the side light emitting layer interface is 0.7 d.
[0046]
Similarly, 30% by volume of the anode side of the luminescent layer and the remaining 70% by volume are the 30% by volume region near the anode side and the other 70% by volume of the luminescent layer between the cathode and the anode. Point.
[0047]
In the present invention, the average content of the luminescent material is the content (% by mass) of the luminescent material in a specified region.
[0048]
In order to satisfy the conditions of the present invention, the concentration state of the light emitting material in the light emitting layer must be changed. In order to change the concentration state of the luminescent material in the luminescent layer, when the luminescent layer is formed by co-evaporation, the deposition rate of the luminescent material or the host compound described later can be changed, or each deposition can be made intermittent. There are ways to do this. There is also a method of laminating solutions having different luminescent material concentrations by wet methods such as printing, ink jetting, and spin coating.
[0049]
The concentration state of the light emitting material in the light emitting layer may be any state as long as the conditions of the present invention are satisfied. For example, it may be stepped as shown in FIGS. It may change continuously like a straight line. Moreover, two combinations like D and E may be sufficient.
[0050]
In the present invention, the light-emitting material is preferably a phosphorescent compound, which can further improve the light emission efficiency.
[0051]
In the case of a phosphorescent organic EL device using a phosphorescent compound as a light emitting material, TT annihilation is one of the causes of a decrease in light emission efficiency, but the light emitting material is a hole transporting dopant or electron transport. When the dopant is a conductive dopant, the recombination region does not cover the entire light emitting layer, but a narrow region on the cathode side or the anode side of the light emitting layer, resulting in a high triplet exciton concentration and TT annihilation. However, by adopting the structure of the present invention, it is possible to suppress the recombination region in the light emitting layer, suppress the occurrence of TT annihilation, and improve the light emission efficiency.
[0052]
Next, the constituent layers of the organic EL device of the present invention will be described in more detail.
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.
(1) Anode / hole transport layer / light emitting layer / cathode
(2) Anode / hole transport layer / light emitting layer / electron transport layer / cathode
(3) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode
(4) Anode / hole transport layer / electron blocking layer / light emitting layer / electron transport layer / cathode
(5) Anode / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / cathode
(6) Anode / anode buffer layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode
"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, CuI, indium tin oxide (ITO), SnO.2And conductive transparent materials such as ZnO. IDIXO (In2OThree-ZnO) or other amorphous material capable of producing a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials 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 (100 μm or more) Degree), a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. 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 to 1000 nm, preferably 10 to 200 nm.
[0053]
"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 (Al2OThree) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as a magnesium / silver mixture, magnesium, from the viewpoint of electron injectability and durability against oxidation, etc. / Aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al2OThree) Mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. 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.
[0054]
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.
[0055]
Next, an injection layer, a blocking layer, an electron transport layer and the like used as the constituent layers of the organic EL element of the present invention will be described.
[0056]
<< Buffer layer >>: Cathode buffer layer, anode buffer layer
The injection layer is provided as necessary, and has a cathode buffer layer (electron injection layer) and an anode buffer layer (hole injection layer). As described above, between the anode and the light emitting layer or the hole transport layer, and the cathode and the light emission. You may exist between a layer or an electron carrying layer.
[0057]
The buffer layer is a layer provided between the electrode and the organic layer in order to lower the driving voltage and improve the light emission luminance. “The organic EL element and the forefront of its industrialization (published by NTT Corporation on November 30, 1998) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes an anode buffer layer and a cathode buffer layer.
[0058]
The details of the anode buffer layer (hole injection layer) are described in JP-A Nos. 9-45479, 9-260062, and 8-288069, and a specific example is represented by copper phthalocyanine. Examples thereof include a phthalocyanine buffer layer, an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.
[0059]
The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, 9-17574, 10-74586, and the like, and specifically, strontium, aluminum, and the like are representative. A metal buffer layer, an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide. The buffer layer (injection layer) is desirably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 5 μm.
[0060]
<< Blocking layer >>: Hole blocking layer, electron blocking layer
The hole blocking layer is a layer containing a hole blocking material, and the probability of recombination of electrons and holes in the light emitting layer by blocking the outflow of holes from the light emitting layer while transporting electrons to the light emitting layer. Can be improved.
[0061]
The hole blocking material is a compound capable of blocking holes moving from the light emitting layer and efficiently transporting electrons injected from the cathode direction to the light emitting layer.
[0062]
As physical properties required for the hole blocking material, when the ionization potential Ip1, the electron affinity Ea1 of the light emitting layer, the ionization potential Ip2 of the hole blocking layer, and the electron affinity Ea2,
Ip2-Ip1> Ea2-Ea1
It is.
[0063]
Further, when the hole blocking material is used for a phosphorescent organic EL device, the excited triplet energy of the hole blocking material is larger than the excited triplet of the light emitting layer.
[0064]
When the hole blocking material is used for a fluorescent organic EL element, the excited singlet energy of the hole blocking material is larger than the excited singlet of the light emitting layer.
[0065]
Examples of the hole blocking material include styryl compounds, triazole derivatives, phenanthroline derivatives, oxadiazole derivatives, and boron derivatives.
[0066]
Examples of other hole blocking materials include the exemplified compounds described in JP-A Nos. 2003-31367, 2003-31368, and No. 2721441.
[0067]
The electron blocking layer is a layer containing an electronic device material, and improves the recombination probability of electrons and holes in the light emitting layer by blocking the outflow of electrons from the light emitting layer while transporting holes to the light emitting layer. Can be made.
[0068]
The electron blocking material is a compound that blocks electrons moving from the light emitting layer and can efficiently transport holes injected from the anode toward the light emitting layer.
[0069]
As physical properties required for the electron blocking material, when the ionization potential Ip1, the electron affinity Ea1 of the light emitting layer, the ionization potential Ip3 of the electron blocking layer, and the electron affinity Ea3,
Ea1-Ea3> Ip1-Ip3
Further, when the electron blocking material is used for a phosphorescent organic EL element, the excited triplet energy of the electron blocking material is larger than the excited triplet of the light emitting layer.
[0070]
When the electron blocking material is used in a fluorescent organic EL element, the excited singlet energy of the electron blocking material is larger than the excited singlet of the light emitting layer.
[0071]
Examples of the electron blocking material include triarylamine derivatives and carbazole derivatives.
[0072]
The ionization potential is defined as the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of a compound to the vacuum level. Specifically, electrons from a compound in a film state (layer state) This is the energy required for extraction, which can be measured directly by photoelectron spectroscopy. For example, it can be measured by ESCA 5600 UPS (ultraviolet photoemission spectroscopy) manufactured by ULVAC-PHI.
[0073]
The electron affinity is defined as the energy at which electrons in the vacuum level fall to the LUMO (lowest molecular orbital) level of the material and stabilize,
Electron affinity (eV) = ionization potential Ip (eV) + band gap (eV)
Can be obtained. The band gap represents the energy between HOMO and LUMO of a compound. Specifically, it can be obtained from the absorption edge by preparing a film on a quartz substrate, measuring the absorption spectrum.
[0074]
<Light emitting layer>
The light emitting layer according to the present invention is a layer that contains a light emitting material and emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer. The portion that emits light may be within the layer of the light emitting layer or at the interface between the light emitting layer and the adjacent layer.
[0075]
As the light-emitting material, a known light-emitting material used for a light-emitting layer of an organic EL element can be used. For example, quinacridone, DCM, coumarin derivatives, rhodamine, rubrene, decacyclene, pyrazoline derivatives, squarylium derivatives, europium complexes and the like are typical examples. Known fluorescent compounds mentioned as above can also be used.
[0076]
In the present invention, it is preferable to use a phosphorescent compound as described above, which can further improve the luminous efficiency.
[0077]
The phosphorescent compound according to the present invention can be used by appropriately selecting from known compounds used for the light emitting layer of the organic EL device. For example, an iridium complex listed in JP-A No. 2001-247859 or a formula shown in WO 00 / 70,655, pages 16 to 18, for example, tris (2-phenylpyridine) iridium, etc. Examples of the dopant include platinum complexes such as platinum complex, osmium complex, and 2,3,7,8,12,13,17,18-octaethyl-21H, 23H-porphyrin platinum complex. By using such a phosphorescent compound as a dopant, a light-emitting organic EL device with high internal quantum efficiency can be realized.
[0078]
The phosphorescent compound according to the present invention is preferably a complex compound containing a group 8 metal in the periodic table of elements, more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex compound). ), Rare earth complexes, and most preferred are iridium compounds.
[0079]
Specific examples of the phosphorescent compound used in the present invention are shown below, but are not limited thereto. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711, and the like.
[0080]
[Chemical 1]
[0081]
[Chemical 2]
[0082]
[Chemical Formula 3]
[0083]
[Formula 4]
[0084]
In addition, for example, J. et al. Am. Chem. Soc. 123, 4304-4312 (2001), WO00 / 70655, WO02 / 15645, JP2001-247859, JP2001-345183, JP2002-117978, JP2002-170684, special JP 2002-203678, JP 2002-235076, JP 2002-302671, JP 2002-324679, JP 2002-332291, JP 2002-332292, JP 2002-338588, etc. The iridium complex mentioned by general formula of this, the iridium complex mentioned as a specific example, the iridium complex represented by Formula (IV) of Unexamined-Japanese-Patent No. 2002-8860, etc. are mentioned.
[0085]
The phosphorescent compound according to the present invention has a phosphorescence quantum yield in solution of 0.001 or more at 25 ° C. Preferably, it is 0.01 or more. Furthermore, it is preferably 0.1 or more.
[0086]
The phosphorescence quantum yield can be measured by the method described in Spectroscopic II, page 398 (1992 edition, Maruzen) of the 4th edition, Experimental Chemistry Course 7.
[0087]
There are two types of light emission of phosphorescent compounds in principle. One is the recombination of carriers on the host compound to which carriers are transported to generate an excited state of the host compound, and this energy is phosphorescent. Energy transfer type to obtain light emission from the phosphorescent compound by transferring to the compound, the other is that the phosphorescent compound becomes a carrier trap, carrier recombination occurs on the phosphorescent compound, and from 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.
[0088]
In the present invention, the phosphorescent maximum wavelength of the phosphorescent compound is not particularly limited. In principle, the phosphorescent compound can be obtained by selecting a central metal, a ligand, a ligand substituent, and the like. However, it is preferable that the phosphorescent compound has a phosphorescent maximum wavelength of 380 to 480 nm. As what has such a phosphorescence emission wavelength, the organic EL element which light-emits blue and the organic EL element which light-emits white are mentioned.
[0089]
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.
[0090]
The light emitting layer may contain a host compound in addition to the phosphorescent compound.
In the present invention, the host compound is a compound having a phosphorescence quantum yield of phosphorescence emission of less than 0.01 at room temperature (25 ° C.) among compounds contained in the light emitting layer.
[0091]
In the present invention, it is preferable to use a known host compound as the host compound. Thereby, the luminous efficiency can be further increased.
[0092]
Furthermore, 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.
[0093]
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.
[0094]
Specific examples of known host compounds include compounds described in the following documents.
[0095]
JP 2001-257076, JP 2002-308855, JP 2001-313179, JP 2002-319491, JP 2001-357777, JP 2002-334786, JP 2002-8860, JP 2002-334787, JP 2002-15871, JP2002-334788, JP2002-43056, JP2002-334789, JP2002-756645, JP2002-338579, JP2002-105445, JP2002-343568, JP2002 141173, JP2002-352957, JP2002203683, JP2002-363227, JP2002-231453, JP2003-3165, JP2002-234888, JP2003-27048, JP200. -255934, JP 2002-260861, JP 2002-280183, JP 2002-299060, JP 2002-302516, JP 2002-305083, JP 2002-305084, 2002-308837, etc. JP.
[0096]
Moreover, the light emitting layer may contain the host compound which has a fluorescence maximum wavelength further as a host compound. In this case, the energy transfer from the other host compound and the phosphorescent compound to the fluorescent compound allows electroluminescence as an organic EL element to be emitted from the other host compound having a fluorescence maximum wavelength. A host compound having a fluorescence maximum wavelength is preferably a compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, particularly preferably 30% or more. Specific host compounds having a maximum fluorescence wavelength include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Perylene dyes, stilbene dyes, polythiophene dyes, and the like. The fluorescence quantum yield can be measured by the method described in 362 (1992, Maruzen) of Spectroscopic II of the Fourth Edition Experimental Chemistry Course 7.
[0097]
The color emitted in this specification is the spectral radiance meter CS-1000 (Minolta) in FIG. 4.16 on page 108 of “New Color Science Handbook” (Edited by the Japan Society for Color Science, University of Tokyo Press, 1985). It is determined by the color when the measured result is applied to the CIE chromaticity coordinates.
[0098]
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. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, 5 nm-5 micrometers, Preferably it is chosen in the range of 5 nm-200 nm. The light emitting layer may have a single layer structure in which these phosphorescent compounds and host compounds are composed of one or more kinds, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. Good.
[0099]
《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.
[0100]
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, 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, stilbenes Derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, particularly thiophene oligomers, and the like can be given.
[0101]
As the hole transport material, those described above can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.
[0102]
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, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, 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 (MTDATA) in which three triphenylamine units described in No. 88 are linked in a starburst type ) And the like.
[0103]
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.
[0104]
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. This hole transport layer may have a single layer structure composed of one or more of the above materials.
[0105]
《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.
[0106]
The electron transport material only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and the material can be selected and used from conventionally known compounds. Examples include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide 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.
[0107]
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.
[0108]
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), etc., and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga, or Pb can also be used as an 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.
[0109]
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.
[0110]
<< Substrate (also referred to as substrate, substrate, support, etc.) >>
The organic EL device of the present invention is preferably formed on a substrate.
[0111]
The substrate of the organic EL device of the present invention is not particularly limited to the type of glass, plastic, etc., and is not particularly limited as long as it is transparent. Examples of substrates that are preferably used include glass, quartz, A light transmissive resin film can be mentioned. A particularly preferable substrate is a resin film that can give flexibility to the organic EL element.
[0112]
Examples of the resin film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose triacetate. Examples thereof include films made of (TAC), cellulose acetate propionate (CAP) and the like. An inorganic or organic film or a hybrid film of both may be formed on the surface of the resin film.
[0113]
The external extraction efficiency at room temperature for light emission of the organic electroluminescence 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.
[0114]
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.
[0115]
<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, an organic EL device comprising an anode / anode buffer layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode A manufacturing method of will be described.
[0116]
First, a thin film made of a desired electrode material, for example, an anode material 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, thereby producing an anode. To do. Next, organic compound thin films of an anode buffer layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, and a cathode buffer layer, which are organic EL element materials, are formed thereon.
[0117]
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. From the point of being difficult to form, a vacuum deposition method, a spin coating method, an ink jet method, and a printing method are particularly preferable. Further, different film forming methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C. and a degree of vacuum of 10-6-10-2It is desirable to appropriately select Pa, vapor deposition rate of 0.01 to 50 nm / second, substrate temperature of −50 to 300 ° C., film thickness of 0.1 nm to 5 μm, preferably 5 to 200 nm.
[0118]
After these layers are formed, 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 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. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.
[0119]
The multicolor display device of the present invention is provided with a shadow mask only when the light emitting layer is formed, and the other layers are common, so that patterning of the shadow mask or the like is not necessary. A film can be formed by a method or a printing method.
[0120]
When patterning is performed only on the light-emitting layer, the method is not limited, but a vapor deposition method, an inkjet method, and a printing method are preferable. In the case of using a vapor deposition method, patterning using a shadow mask is preferable.
[0121]
Moreover, it is also possible to reverse the manufacturing 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.
[0122]
The display device of the present invention can be used as a display device, a display, and various light emission sources. In a display device or a display, full-color display is possible by using three types of organic EL elements of blue, red, and green light emission.
[0123]
Examples of the display device and display include a television, a personal computer, a mobile device, an AV device, a character broadcast display, and an information display in an automobile. In particular, it may be used as a display device for reproducing still images and moving images, and the driving method when used as a display device for reproducing moving images may be either a simple matrix (passive matrix) method or an active matrix method.
[0124]
The lighting device of the present invention includes home lighting, interior lighting, clock and liquid crystal backlights, billboard advertisements, traffic lights, light sources of optical storage media, light sources of electrophotographic copying machines, light sources of optical communication processors, light sensors Although a light source etc. are mentioned, it is not limited to this.
[0125]
Further, the organic EL element according to the present invention may be used as an organic EL element having a resonator structure.
[0126]
Examples of the purpose of use of the organic EL element having such a resonator structure include a light source of an optical storage medium, a light source of an electrophotographic copying machine, a light source of an optical communication processing machine, and a light source of an optical sensor. It is not limited. Moreover, you may use for the said use by making a laser oscillation.
[0127]
<Display device>
The organic EL element of the present invention may be used as one kind of lamp for illumination or exposure light source, a projection device for projecting an image, or a display for directly viewing a still image or a moving image. It may be used as a device (display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using three or more organic EL elements of the present invention having different emission colors. Alternatively, it is possible to make one color emission color, for example, white emission, into BGR by using a color filter to achieve full color. Furthermore, it is possible to convert the emission color of the organic EL to another color by using a color conversion filter, and in this case, λmax of the organic EL emission is preferably 480 nm or less.
[0128]
An example of a display device composed of the organic EL element of the present invention will be described below with reference to the drawings.
[0129]
FIG. 3 is a schematic diagram illustrating an example of a display device including organic EL elements. It is a schematic diagram of a display such as a mobile phone that displays image information by light emission of an organic EL element.
[0130]
The display 1 includes a display unit A having a plurality of pixels, a control unit B that performs image scanning of the display unit A based on image information, and the like.
[0131]
The control unit B is electrically connected to the display unit A, and sends a scanning signal and an image data signal to each of the plurality of pixels based on image information from the outside. The pixels for each scanning line are converted into image data signals by the scanning signal. In response to this, light is sequentially emitted and image scanning is performed to display image information on the display unit A.
[0132]
FIG. 4 is a schematic diagram of the display unit A.
The display unit A includes a wiring unit including a plurality of scanning lines 5 and data lines 6, a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below. FIG. 3 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).
[0133]
The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions (details are shown in FIG. Not shown).
[0134]
When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data. Full color display is possible by appropriately arranging pixels in the red region, the green region, and the blue region that emit light on the same substrate.
[0135]
Next, the light emission process of the pixel will be described.
FIG. 5 is a schematic diagram of a pixel.
[0136]
The pixel includes an organic EL element 10, a switching transistor 11, a driving transistor 12, a capacitor 13, and the like. A full color display can be performed by using red, green, and blue light emitting organic EL elements as the organic EL elements 10 in a plurality of pixels, and juxtaposing them on the same substrate.
[0137]
In FIG. 6, an image data signal is applied from the control unit B to the drain of the switching transistor 11 through the data line 6. When a scanning signal is applied from the control unit B to the gate of the switching transistor 11 via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is supplied to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.
[0138]
By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the drive of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10, and the power supply line 7 connects to the organic EL element 10 according to the potential of the image data signal applied to the gate. Current is supplied.
[0139]
When the scanning signal is moved to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, even if the driving of the switching transistor 11 is turned off, the capacitor 13 maintains the potential of the charged image data signal, so that the driving of the driving transistor 12 is kept on and the next scanning signal is applied. Until then, the light emission of the organic EL element 10 continues. When the scanning signal is next applied by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.
[0140]
That is, the organic EL element 10 emits light by the switching transistor 11 and the drive transistor 12 that are active elements for the organic EL element 10 of each of the plurality of pixels, and the light emission of the organic EL element 10 of each of the plurality of pixels 3. It is carried out. Such a light emitting method is called an active matrix method.
[0141]
Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations by a multi-value image data signal having a plurality of gradation potentials, or on / off of a predetermined light emission amount by a binary image data signal. But you can.
[0142]
The potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.
[0143]
In the present invention, not only the active matrix method described above, but also a passive matrix light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.
[0144]
FIG. 6 is a schematic diagram of a passive matrix display device. In FIG. 5, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a lattice shape so as to face each other with the pixel 3 interposed therebetween.
[0145]
When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal. In the passive matrix system, the pixel 3 has no active element, and the manufacturing cost can be reduced.
[0146]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, the embodiment of this invention is not limited to these.
[0147]
  referenceExample 1
  <Preparation of organic EL elements 1-1 to 1-4>
  Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum deposition apparatus, while 200 mg of m-MTDATA is put in a molybdenum resistance heating boat, and 200 mg of NPD is put in another molybdenum resistance heating boat, and another molybdenum resistance is put. Add 100 mg of rubrene to a heated boat, and add Alq to another molybdenum resistance heated boat.3200 mg was added and attached to a vacuum deposition apparatus.
[0148]
The vacuum chamber is then 4 × 10-FourAfter reducing the pressure to Pa, the heating boat containing m-MTDATA was energized and heated, and deposited on a transparent support substrate at a deposition rate of 0.1 nm / sec to provide a 50 nm hole transport layer.
[0149]
Further, the heating boat containing NPD and rubrene is energized and heated, and a 30 nm light emitting layer is provided by co-deposition on the hole transport layer at a deposition rate of 0.2 nm / sec and 0.01 nm / sec, respectively. It was.
[0150]
Furthermore, AlqThreeThe heating boat containing power was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / sec to provide an electron transport layer having a thickness of 40 nm.
[0151]
In addition, the substrate temperature at the time of vapor deposition was room temperature.
Then, 0.5 nm of lithium fluoride was vapor-deposited as a cathode buffer layer, and also aluminum 110nm was vapor-deposited, the cathode was formed, and the organic EL element 1-1 was produced.
[0152]
In preparation of the organic EL element 1-1, the vapor deposition conditions of the light emitting layer were adjusted, and the average content of the light emitting material of 30% volume on the anode side and the average content of the remaining 70 volume% of the light emitting material are shown in Table 1. Organic EL elements 1-2 to 1-4 were produced in the same manner as the organic EL element 1-1 except for the above.
[0153]
[Chemical formula 5]
[0154]
[Table 1]
[0155]
  <Evaluation of Organic EL Elements 1-1 to 1-4>
  referenceEvaluation of the organic EL devices 1-1 to 1-4 produced in the same manner as in Example 1 was performed, and the results were displayed.2Shown in
[0156]
  table2The measurement result of the light emission lifetime was expressed as a relative value when the organic EL element 1-1 was taken as 100.
[0157]
[Table 2]
[0158]
  From Table 2YesEL element1-2 to 1-4Was found to have a long life.
  Example 2
  <Preparation of organic EL elements 2-1 to 2-4>
  Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum evaporation apparatus. On the other hand, 200 mg of NPD is put in a molybdenum resistance heating boat, 200 mg of CBP is put in another molybdenum resistance heating boat, and another molybdenum resistance heating boat is placed. 100 mg of Ir-1 is put in, 200 mg of BCP is put in another molybdenum resistance heating boat, and Alq is put in another resistance heating boat made of molybdenum.3200 mg was added and attached to a vacuum deposition apparatus.
[0159]
The vacuum chamber is then 4 × 10-FourAfter reducing the pressure to Pa, the heating boat containing NPD was energized and heated, and deposited on a transparent support substrate at a deposition rate of 0.1 nm / sec to provide a 50 nm hole transport layer.
[0160]
Further, the heating boat containing CBP and Ir-1 was energized and heated, and co-evaporated on the hole transport layer at a deposition rate of 0.2 nm / sec and 0.01 nm / sec, respectively, to form a 30 nm light emitting layer Was established.
[0161]
Further, the heating boat containing BCP was energized and heated, and was deposited on the light emitting layer at a deposition rate of 0.1 nm / sec to provide a 10 nm hole blocking layer.
[0162]
Furthermore, AlqThreeThe heating boat containing was heated by energizing, and deposited on the hole blocking layer at a deposition rate of 0.1 nm / sec to provide an electron transport layer having a thickness of 40 nm.
[0163]
In addition, the substrate temperature at the time of vapor deposition was room temperature.
Then, 0.5 nm of lithium fluoride was vapor-deposited as a cathode buffer layer, and also aluminum 110nm was vapor-deposited, the cathode was formed, and the organic EL element 2-1 was produced.
[0164]
In the production of the organic EL element 2-1, the vapor deposition conditions of the light emitting layer were adjusted, and the average content of the light emitting material of 30% volume on the cathode side and the average content of the remaining 70% by volume of light emitting material are shown in Table 1. Organic EL elements 2-2 to 2-4 were produced in the same manner as organic EL element 2-1, except that the above was done.
[0165]
[Chemical 6]
[0166]
[Table 3]
[0167]
<Evaluation of organic EL elements 2-1 to 2-4>
Evaluation of the light emission lifetime of the organic EL elements 2-1 to 2-4 produced in the same manner as in Example 1, and evaluation of the light emission efficiency of the organic EL elements 2-1 to 2-4 produced as follows. Went. The results are shown in Table 4.
[0168]
(External extraction quantum efficiency)
About the produced organic EL element, 2.5 mA / cm under 23 degreeC and dry nitrogen gas atmosphere2The external extraction quantum efficiency (%) when a constant current was applied was measured. For the measurement, a spectral radiance meter CS-1000 (manufactured by Minolta) was used in the same manner.
[0169]
The measurement results of the light emission lifetime and the light emission efficiency in Table 4 are expressed as relative values when the organic EL element 2-1 is 100.
[0170]
[Table 4]
[0171]
From Table 4, it was found that the organic EL device of the present invention has a long lifetime, and in particular, when a phosphorescent compound is used as the light emitting material, the light emission efficiency is also improved.
[0172]
Example 3
<Preparation of organic EL elements 3-1 to 3-4>
Transparent support provided with this ITO transparent electrode after patterning on a substrate (NH45 manufactured by NH Techno Glass) made of ITO (indium tin oxide) with a thickness of 100 nm on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes. This transparent support substrate is fixed to a substrate holder of a commercially available vacuum vapor deposition apparatus. Meanwhile, 200 mg of m-MTDATXA is put in a molybdenum resistance heating boat, and 200 mg of compound 1 is put in another resistance heating boat made of molybdenum. 100 mg of Ir-12 is put into a resistance heating boat, 200 mg of compound 2 is put into another resistance heating boat made of molybdenum, and Alq is put into another resistance heating boat made of molybdenum.Three200 mg was added and attached to a vacuum deposition apparatus.
[0173]
The vacuum chamber is then 4 × 10-FourAfter reducing the pressure to Pa, the heating boat containing m-MTDATXA was energized and heated, and deposited on a transparent support substrate at a deposition rate of 0.1 nm / sec to provide a 40 nm hole transport layer.
[0174]
Further, the heating boat containing the compound 1 and Ir-12 was energized and heated, and co-evaporated on the hole transport layer at a deposition rate of 0.2 nm / sec and 0.01 nm / sec, respectively, to emit light of 30 nm. A layer was provided.
[0175]
Further, the heating boat containing the compound 2 was energized and heated, and deposited on the light emitting layer at a deposition rate of 0.1 nm / sec to provide a 10 nm hole blocking layer.
[0176]
Furthermore, AlqThreeThe heating boat containing was heated by energizing and deposited on the hole blocking layer at a deposition rate of 0.1 nm / sec to provide an electron transport layer having a thickness of 20 nm.
[0177]
In addition, the substrate temperature at the time of vapor deposition was room temperature.
Then, 0.5 nm of lithium fluoride was vapor-deposited as a cathode buffer layer, and also aluminum 110nm was vapor-deposited, the cathode was formed, and the organic EL element 3-1 was produced.
[0178]
In the production of the organic EL element 3-1, the vapor deposition conditions of the light emitting layer were adjusted, and the average content of the light emitting material of 30% by volume on the cathode side and the average content of the remaining 70% by volume of the light emitting material are shown in Table 1. Organic EL elements 3-2 to 3-4 were produced in the same manner as the organic EL element 3-1, except that the above was done.
[0179]
[Chemical 7]
[0180]
[Table 5]
[0181]
<Evaluation of organic EL elements 3-1 to 3-4>
The light emitting lifetime of the organic EL elements 3-1 to 3-4 produced in the same manner as in Example 1 was evaluated, and the luminous efficiency of the organic EL elements 3-1 to 3-4 produced in the same manner as in Example 2 was evaluated. Evaluation was performed. The results are shown in Table 6.
[0182]
The measurement results of the light emission lifetime and the light emission efficiency in Table 6 are expressed as relative values when the organic EL element 3-1 is 100.
[0183]
[Table 6]
[0184]
From Table 6, it was found that the organic EL device of the present invention has a long lifetime, and in particular, when a phosphorescent compound is used as the light emitting material, the light emission efficiency is also improved.
[0185]
Example 4
<Production of full-color display device>
<Full-color display device (1)>
(Blue light emitting organic EL device)
The organic EL element 3-4 produced in Example 3 was used.
[0186]
(Green light-emitting organic EL device)
The organic EL element 2-4 produced in Example 2 was used.
[0187]
(Red light emitting organic EL device)
In the organic EL element 2-4 produced in Example 2, the organic EL element 2-4R produced by the same method as the organic EL element 2-4 was used except that Ir-9 was used instead of Ir-1. It was.
[0188]
The red, green and blue light-emitting organic EL elements are juxtaposed on the same substrate to produce an active matrix type full-color display device having the form shown in FIG. 3, and FIG. 4 shows the display of the produced display device. Only the schematic diagram of part A is shown. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 on the same substrate, and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) The scanning lines 5 and the plurality of data lines 6 in the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a lattice shape and are connected to the pixels 3 at the orthogonal positions ( Details are not shown). The plurality of pixels 3 are driven by an active matrix system provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 5. Then, an image data signal is received from the data line 6 and light is emitted according to the received image data. In this way, a full color display device was produced by appropriately juxtaposing the red, green, and blue pixels.
[0189]
It was confirmed that by driving the full-color display device, a full-color moving image display with a high luminance and luminous efficiency and a long life could be obtained.
[0190]
Example 5
In the organic EL element 3-4 produced in Example 3, the organic EL element 3 was used except that Ir-6 and Ir-9 (Ir-6: Ir-9 = 1: 4) were used instead of Ir-12. Organic EL element 3-4W produced by the same method as -4 was produced.
[0191]
The non-light-emitting surface of the organic EL element 3-4W was covered with a glass case to obtain a lighting device. The illuminating device can be used as a thin illuminating device that emits white light with high luminance and luminous efficiency and a long lifetime. FIG. 7 is a schematic view of the lighting device, and FIG. 8 is a cross-sectional view of the lighting device.
[0192]
【The invention's effect】
According to the present invention, an organic electroluminescence element, a lighting device, and a display device that have a long lifetime can be provided.
[0193]
Moreover, the organic electroluminescent element, the illuminating device, and the display apparatus which have high luminous efficiency were able to be provided.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a light emitting layer of an organic EL device of the present invention.
FIG. 2 is a view for explaining a light emitting layer of the organic EL device of the present invention.
FIG. 3 is a schematic diagram illustrating an example of a display device including organic EL elements.
FIG. 4 is a schematic diagram of a display unit.
FIG. 5 is a schematic diagram of a pixel.
FIG. 6 is a schematic diagram of a passive matrix type full-color display device.
FIG. 7 is a schematic view of a lighting device.
FIG. 8 is a cross-sectional view of the lighting device.
[Explanation of symbols]
1 Display
3 pixels
5 scanning lines
6 data lines
7 Power line
10 Organic EL elements
11 Switching transistor
12 Driving transistor
13 Capacitor
A display
B Control unit

Claims (5)

  1. In the organic electroluminescence device having a light emitting layer containing a light emitting material between a cathode and an anode, at least one of the light emitting layers contains a host compound and a hole transporting dopant composed of a phosphorescent compound, and The average content (mass%) of the hole transporting dopant composed of the phosphorescent compound in the region of 30% by volume on the cathode side in the light emitting layer is A, and the remaining 70 volumes excluding the region of 30% by volume on the cathode side. An organic electroluminescence device satisfying the following formula (1 ′), where B is an average content (% by mass) of a hole transporting dopant made of the phosphorescent compound in the region of%.
    0.2 <A / B <0.5 (1 ')
    However, the case where the host compound is the following anthracenedinaphthyl (ADN) and the hole transporting dopant is a distyrylamine derivative (DSA derivative) is excluded.
  2. 2. The organic electroluminescence device according to claim 1, wherein the hole transporting dopant comprises a combination of two or more phosphorescent compounds.
  3. A display device comprising the organic electroluminescence element according to claim 1.
  4. An illuminating device comprising the organic electroluminescent element according to claim 1.
  5.   A display device comprising the lighting device according to claim 4 and a liquid crystal element as a display means.
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