JP4830126B2 - Organic electroluminescence element and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element that achieves high brightness, high light emitting efficiency, and durability especially in blue light emission, and to provide a display device using the same. <P>SOLUTION: The organic EL element includes at least a light emitting layer wherein the light-emitting therefrom comprises phosphorescence emitting. In the element, a carbazole derivative compound given by general expression 1 is contained in any one of layers comprising the organic EL element. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an organic electroluminescence element and a display device, and more particularly to an organic electroluminescence element excellent in light emission luminance, light emission efficiency, and durability and a display device having the same.

  Conventionally, there is an electroluminescence display (ELD) as a light-emitting electronic display device. Examples of the 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.

  On the other hand, an organic EL element has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode. By injecting electrons and holes into the light emitting layer and recombining them, excitons (exciton) Is a device that emits light using the emission of light (fluorescence / phosphorescence) when the exciton is deactivated, and can emit light at a voltage of several V to several tens of V. Further, self-luminescence Since it is a type, it has a wide viewing angle, high visibility, and since it is a thin-film type completely solid element, it has attracted attention from the viewpoint of space saving, portability, and the like.

  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 8-hydroxyquinoline aluminum complex as a host compound. A device having an organic light-emitting layer doped with a trace amount of phosphor (for example, see Patent Document 2), a device having an organic light-emitting layer doped with a quinacridone dye as a host compound using 8-hydroxyquinoline aluminum complex (for example, , See Patent Document 3).

  In the technique disclosed in the above-mentioned patent 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%.

  However, since Princeton University has reported on organic EL devices that use phosphorescence from excited triplets (see, for example, Non-Patent Document 1), research on materials that exhibit phosphorescence at room temperature has become active. (For example, refer nonpatent literature 2 and patent literature 4.).

  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 attracts attention.

  For example, many compounds have been studied focusing on heavy metal complexes such as iridium complexes (see, for example, Non-Patent Document 3).

  Further, studies using tris (2-phenylpyridine) iridium as a dopant have been made (for example, see Non-Patent Document 2).

In addition, L ₂ Ir (acac), for example, (ppy) ₂ Ir (acac) (see, for example, Non-Patent Document 4) as a dopant, and tris (2- (p-tolyl) pyridine) iridium (as a dopant) Studies using Ir (ptpy) ₃ ), tris (benzo [h] quinoline) iridium (Ir (bzq) ₃ ), Ir (bzq) ₂ ClP (Bu) _3, etc. (for example, see Non-Patent Document 5). Has been done.

  In order to obtain high luminous efficiency, a hole transporting compound is used as a host of the phosphorescent compound (see, for example, Non-Patent Document 6).

  Further, various electron transporting materials are used as phosphorescent compound hosts by doping them with a novel iridium complex (see, for example, Non-Patent Document 4). Furthermore, high luminous efficiency is obtained by introducing a hole blocking layer (see, for example, Non-Patent Document 5).

  However, although the external extraction efficiency of nearly 20%, which is the theoretical limit, has been achieved for green light emission, sufficient efficiency has not yet been obtained for other light emission colors, and improvements are necessary. In organic EL elements for practical use, development of organic EL elements that emit light efficiently and with high luminance with low power consumption is further desired.

In order to solve these problems, many compounds have been proposed so far as described above, and carbazole derivatives have been studied as one of such compounds. For example, Patent Document 5 discloses a derivative of N-phenylcarbazole as an electron transport material, and Patent Document 6 discloses biscarbazoles linked via a vinylene group as a hole injection material. . Patent Document 7 proposes a phosphorescent light emitting device using a polymer having a carbazole skeleton. Further, Patent Document 8 discloses a compound in which an aryl group is bonded to the N-position of carbazole. However, all of the organic EL elements using the compounds described in these known documents sufficiently satisfy all the performances such as quantum efficiency, light emission luminance, durability, etc., which are the issues for practical application. I can't say that.
Japanese Patent No. 3093796 Japanese Unexamined Patent Publication No. 63-264692 JP-A-3-255190 US Pat. No. 6,097,147 JP-A-8-60144 Japanese Patent Laid-Open No. 5-194943 Japanese Patent Laid-Open No. 2001-257076 JP 2002-1000047 A M.M. A. Baldo et al. , Nature, 395, 151-154 (1998) M.M. A. Baldo et al. , Nature, 403, 17, 750-753 (2000) S. Lamansky et al. , J .; Am. Chem. Soc. , 123, 4304 (2001) M.M. E. Thompson et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu) Moon-Jae Youn. 0 g, Tsutsuo Tsutsui et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu) Ikai et al. , The 10th International Works on Organic and Organic Electroluminescence (EL'00, Hamamatsu)

  An object of the present invention is to provide an organic EL element and a display device that exhibit high emission luminance, excellent quantum efficiency, and a long half-life. In particular, it is an object of the present invention to provide an organic EL element that achieves both light emission luminance, light emission efficiency, and durability in blue light emission, and a display device using the same and having high light emission luminance and good durability.

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

  1. In an organic electroluminescent element having at least one light emitting layer, and light emission from the light emitting layer includes phosphorescence, a carbazole derivative represented by the following general formula 1 in any one of the layers constituting the organic electroluminescent element An organic electroluminescence device comprising a compound.

(In the formula, A represents an optionally substituted benzene ring, pyrimidine ring, triazine ring or dithienobenzene ring . R ₁ and R ₈ represent a hydrogen atom, and R ₂ , R ₄ , R ₅ and R _7. represents. However represent either hydrogen atoms, a alkylthio group, R _3, R ₆ is a hydrogen atom, a chlorine atom, a trifluoromethyl group, an amino group, an amide group, one cyano group or a heterocyclic group, R ₁ to R ₈ have greens be hydrogen atoms at the same time. n represents 2 or more natural number multiple of the carbazole derivative residue may be the same or different.)
2. 2. The organic electroluminescence device as described in 1 above, wherein the heterocyclic group represented by R ₃ or R ₆ in formula 1 is a thienyl group or a carbazolyl group .

3. 3. The organic electroluminescence device as described in 1 or 2 above, wherein in general formula 1, A is a benzene ring, pyrimidine ring or triazine ring .

  4). 4. The organic electroluminescence device as described in any one of 1 to 3 above, wherein the light emitting layer contains a compound represented by the general formula 1.

  5. 5. A display device comprising the organic electroluminescence element according to any one of 1 to 4 above.

  According to the present invention, it is possible to provide an organic EL element and a display device that exhibit high emission luminance, excellent quantum efficiency, and a long half-life. In particular, in blue light emission, it is possible to provide an organic EL element that achieves both emission luminance, emission efficiency, and durability, and a display device with high emission luminance and durability using the organic EL element.

  Hereinafter, the present invention will be described in detail.

  As a result of intensive studies, the present inventors have at least one light-emitting layer, and in the organic EL element in which light emission from the light-emitting layer includes phosphorescence, the general formula is included in any one layer constituting the organic EL element. It has been found that by including the carbazole derivative compound represented by 1, it is possible to provide an organic EL device and a display device that exhibit high emission luminance, excellent quantum efficiency, and a long half-life.

  The carbazole derivative compound represented by the general formula 1 (hereinafter also referred to as the compound according to the present invention) will be described in detail.

A in the general formula 1 represents an optionally substituted benzene ring, pyrimidine ring, triazine ring or dithienobenzene ring. Further, it may be a condensed aromatic ring residue by any combination of these aromatic ring residues, and examples of such condensed aromatic ring residues include naphthalene, anthracene, dithienobenzene, carbazole, quinoline and the like. Although it is possible, it is more preferably a monocyclic aromatic ring residue which is not condensed. These aromatic ring residues may have a substituent, and examples of the substituent include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, (t) butyl group, pentyl group, hexyl group). Group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group etc.), cycloalkyl group (eg cyclopentyl group, cyclohexyl group etc.), alkenyl group (eg vinyl group, allyl group etc.), alkynyl group (eg , Propargyl group etc.), aryl group (eg phenyl group, naphthyl group etc.), heterocyclic group (eg pyridyl group, thiazolyl group, oxazolyl group, imidazolyl group, furyl group, pyrrolyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group) Group, selenazolyl group, sulfolanyl group, piperidinyl group, pyrazolyl group, tetrazolyl Etc.), halogen atoms (eg chlorine atom, bromine atom, iodine atom, fluorine atom etc.), alkoxyl groups (eg methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyl) Oxy group etc.), cycloalkoxyl group (eg cyclopentyloxy group, cyclohexyloxy group etc.), aryloxy group (eg phenoxy group, naphthyloxy group etc.), alkylthio group (eg methylthio group, ethylthio group, propylthio group, Pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, , Methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group ( For example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group , 2-pyridylaminosulfonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylurea). Id group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group) Octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyl) Oxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino) Propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, Aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group Naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), sulfinyl group (for example, methylsulfinyl group) Ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group or arylsulfonyl group (for example, methylsulfonyl) Group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (for example, amino group, ethylamino) Group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2- Pyridylamino group, etc.), nitro group, cyano group, hydroxyl group, halogen atom and the like. These groups may be further substituted with the above substituents, or they may be condensed with each other to form a ring.

In formula _1, R 1, _{R 8} represents a hydrogen _{atom, R 2, R 4, R} 5, R 7 represents any one of a hydrogen atom, A alkylthio _group, R 3, _{R 6} is a hydrogen atom, a chlorine It represents an atom, a trifluoromethyl group, an amino group, an amide group, a cyano group or a heterocyclic group. The heterocyclic group is preferably a thienyl group or a carbazolyl group. However, R _{1 to} R ₈ do not simultaneously become hydrogen atoms. Bonded to A in the general formula 1 is a carbazole derivative residue.

In general formula 1, at least one of R ₂ , R ₃ , R ₆ and R ₇ is a substituent (fluorine atom, alkylthio group, chlorine atom, trifluoromethyl group, amino group, amide group, cyano group or heterocyclic group) It is preferable that

  In the general formula 1, n represents a natural number. When n is 2 or more, a plurality of carbazole derivative residues are bonded to the aromatic ring skeleton represented by A. The groups can be the same or different.

  The compound according to the present invention can be used for any of a hole transport layer, an electron transport layer, and a light emitting layer of an organic EL device to be described later, but is preferably an electron transport layer or a light emitting layer, particularly preferably a light emitting layer. When used as a material known as “host compound” by engineers engaged in the art, it does not emit light itself by transferring energy to the phosphorescent compound. An organic EL element exhibiting high performance can be produced. Although it is not clear why the compound according to the present invention can exhibit excellent characteristics with respect to known materials or the operation mechanism, a carbazole residue having no substituent is in operation as an organic EL device or It is presumed that the stability of the material is impaired because it decomposes due to electrical and thermal energy during storage, especially during operation, or because it decomposes due to an undesirable chemical reaction in the excited state. The It is considered that the compound according to the present invention can reduce such instability by having a substituent, and is thus suitable for production of a highly durable organic EL device.

Examples of carbazole derivative residues constituting the partial structure of the compound according to the present invention are shown as Z _{01 to} Z ₀₇ below, and examples of the compound according to the present invention having these partial structures as 1 to 6 are shown. However, the embodiment of the present invention is not limited by the structures of Z _{01 to} Z ₀₇ and 1 to 6.

  Moreover, it is preferable that the molecular weight of the compound based on this invention is 600-2000. When the molecular weight is 600 to 2000, Tg (glass transition temperature) increases, thermal stability is improved, and device lifetime is improved. A more preferred molecular weight is 800-2000.

  The compounds according to the present invention are disclosed in Tetrahedron Lett. 39 (1998), 2367-2370, Japanese Patent No. 3161360, Angew. Chem. Int. Ed. 37 (1998), 2046-2067, Tetrahedron Lett. , 41 (2000), pages 481-484, Synth. Commun. , 11 (7), (1981), pages 513-519, and Chem. Rev. , 2002, 102, pages 1359 to 1469, etc., and can be produced by synthetic methods well known to those skilled in the art.

<< Constituent layers of organic EL elements >>
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 << 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, 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. 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.

"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, 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 mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) 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.

  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 hole transport layer, an electron transport layer, etc. 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, between the anode and the light emitting layer or the hole transport layer, and You may exist between a cathode, a light emitting layer, or an electron carrying layer.

  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 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.

  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.

<< 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, JP-A Nos. 11-204258 and 11-204359, and “Organic EL devices and their forefront of industrialization” (published by NTS Corporation on November 30, 1998), etc. There is a hole blocking layer.

  The hole blocking layer is an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons and has a very small ability to transport holes. By blocking holes while transporting electrons, And the recombination probability of holes can be improved.

  On the other hand, the electron blocking layer is a hole transport layer in a broad sense, made of a material that has a function of transporting holes and has a very small ability to transport electrons, and blocks electrons while transporting holes. Thus, the probability of recombination of electrons and holes can be improved.

  The hole transport layer is made of a 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 and the electron transport layer can be provided as a single layer or a plurality of layers.

  In the organic EL device of the present invention, the excited triplet energy of all materials of the host of the light emitting layer, the hole transport layer adjacent to the light emitting layer, and the electron transport layer adjacent to the light emitting layer is the excited triplet energy of the phosphorescent dopant. Is preferably larger. In particular, the wavelength of the 0-0 band in the phosphorescence spectrum of the host of the light emitting layer, the hole transport layer adjacent to the light emitting layer, and the electron transport layer adjacent to the light emitting layer is preferably 450 nm or less.

<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 material used for the light emitting layer (hereinafter referred to as the light emitting material) is preferably an organic compound or complex that emits fluorescence or phosphorescence, and is appropriately selected from known materials used for the light emitting layer of the organic EL device. Can be used. Such a light-emitting material is mainly an organic compound, and has a desired color tone, for example, Macromol. Synth. 125, pages 17 to 25, and the like. The light emitting material may have a hole transport function and an electron transport function in addition to the light emitting performance, and most of the hole transport material and the electron transport material can be used as the light emitting material. The light emitting material may be a polymer material such as p-polyphenylene vinylene or polyfluorene, and a polymer material in which the light emitting material is introduced into a polymer chain or the light emitting material is used as a polymer main chain is used. May be.

  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, or an LB 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 5-200 nm. This light emitting layer may have a single layer structure composed of one or more of these light emitting materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. A preferred embodiment of the organic EL device of the present invention is when the light emitting layer is composed of two or more materials, and one of them is the compound of the present invention.

  In addition, as described in JP-A-57-51781, this light-emitting layer is prepared by dissolving the above light-emitting material in a solvent together with a binder such as resin to form a thin film by spin coating or the like. Can be formed. There is no restriction | limiting in particular about the film thickness of the light emitting layer formed in this way, Although it can select suitably according to a condition, Usually, it is the range of 5 nm-5 micrometers, Preferably it is the range of 5-200 nm.

(Host compound)
“Host compound (hereinafter also simply referred to as host)” means a compound having the largest mixing ratio (mass) in a light-emitting layer composed of two or more kinds of compounds. It is called “dopant compound (also simply referred to as dopant)”. For example, if the light emitting layer is composed of two types of compound A and compound B and the mixing ratio is A: B = 10: 90, compound A is a dopant compound and compound B is a host compound. Furthermore, if a light emitting layer is comprised from 3 types of compound A, compound B, and compound C, and the mixing ratio is A: B: C = 5: 10: 85, compound A and compound B are dopant compounds, Compound C is a host compound.

  The host compound of the light emitting layer is preferably an organic compound or a complex, and in the present invention, the excited triplet energy of the host compound is preferably larger than the excited triplet energy of the phosphorescent dopant. Further, the wavelength of the 0-0 band in the phosphorescence spectrum of the host compound is preferably 450 nm or less. Thereby, visible light, in particular, BGR emission can be performed.

  That is, by making the excited triplet energy of the host compound larger than the excited triplet energy of the phosphorescent dopant, energy transfer type dopant emission from the host compound to the dopant is possible. In addition, a compound having a 0-0 band wavelength of 450 nm or less in the phosphorescence spectrum of the host compound has a very wide energy gap (ionization potential-electron affinity, HOMO-LUMO).

  As such a host compound, an arbitrary one can be selected and used from known materials used in organic EL devices, and most of the hole transport materials and electron transport materials described below are light emitting layer host compounds. Can also be used.

  A polymer material such as polyvinyl carbazole or polyfluorene may be used, and a polymer material in which the host compound is introduced into a polymer chain or the host compound as a polymer main chain may be used.

  As the host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable.

(Dopant)
Next, the dopant will be described.

  There are two types of principles. One is the recombination of carriers on the host to which the carriers are transported to generate an excited state of the host compound, and this energy is transferred to the dopant to obtain light emission from the dopant. The other is the carrier trap type in which the dopant becomes a carrier trap, and carrier recombination occurs on the dopant compound and light emission from the dopant is obtained. In either case, the dopant compound is excited. The condition is that the energy of the state is lower than the energy of the excited state of the host compound.

  The “phosphorescent dopant” and “phosphorescent compound” in the present invention are compounds in which light emission from an excited triplet is observed, and are compounds having a phosphorescence quantum yield of 0.001 or more at 25 ° C. The phosphorescence quantum yield is preferably 0.01 or more, more 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 dopant used for this invention should just achieve the said phosphorescence quantum yield in arbitrary solvents.

  The phosphorescent dopant used in 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, most preferably iridium compounds.

  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.

  In the present invention, the phosphorescent maximum wavelength of the phosphorescent compound is not particularly limited, and in principle, light emission obtained by selecting a central metal, a ligand, a ligand substituent, and the like. The wavelength can be changed. A plurality of host compounds and phosphorescent dopants may be used. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. In addition, by using a plurality of phosphorescent dopants, 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 dopant and the amount of doping, and can also be applied to illumination and backlight.

  In another embodiment, in addition to the host compound and the phosphorescent compound, there may be a case where at least one fluorescent compound having a fluorescence maximum wavelength is contained in a wavelength region longer than the maximum wavelength of light emission from the phosphorescent compound. . In this case, electroluminescence as an organic EL element can be emitted from the fluorescent compound by energy transfer from the host compound and the phosphorescent compound to the fluorescent compound. Preferred as the fluorescent compound is one 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 fluorescent compounds include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, Examples include stilbene dyes and polythiophene dyes. 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.

  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.

  This light emitting layer can be formed by thinning a phosphorescent dopant and a host compound 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 a light emitting layer, Usually, 5 nm-about 5 micrometers, Preferably it is 5-200 nm.

《Hole transport layer》
The hole transport layer is made of a 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 is not particularly limited, and is conventionally used as a hole charge injection / transport material in an optical transmission material or a well-known material used for a hole injection layer or a hole transport layer of an EL element. Any one can be selected and used.

  The hole transport material has 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.

  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.

  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.

  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.

  In the present invention, the excited triplet energy of the hole transport material in the hole transport layer adjacent to the light emitting layer is preferably larger than the excited triplet energy of the phosphorescent dopant. Furthermore, the wavelength of the 0-0 band in the phosphorescence spectrum of the hole transport material of the hole transport layer adjacent to the light emitting layer is preferably 450 nm or less. That is, the hole transport material is preferably a compound that has a hole transport ability, prevents deactivation of light emission from the phosphorescent dopant, and has a high Tg.

  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.

《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-layer electron transport layer and a plurality of layers, the following materials are used as the electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer. Are known.

  Further, the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material can be selected from conventionally known compounds. .

  Examples of materials used for this electron transport layer (hereinafter referred to as electron transport materials) 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.

  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), 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 A semiconductor can also be used as an electron transport material.

  In the present invention, the excited triplet energy of the electron transport material in the electron transport layer adjacent to the light emitting layer is preferably larger than the excited triplet energy of the phosphorescent dopant. Furthermore, the wavelength of the 0-0 band in the phosphorescence spectrum of the electron transport material of the electron transport layer adjacent to the light emitting layer is preferably 450 nm or less.

  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.

<< Substrate (also referred to as substrate, substrate, support, etc.) >>
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.

  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.

  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.

  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.

<< 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, 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, 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 described above, there are spin coating methods, casting methods, ink jet methods, vapor deposition methods, printing methods, and the like as methods for thinning the organic compound thin films, but it is easy to obtain a uniform film and pinholes are not easily generated. In view of the above, a printing method including a vacuum deposition method, a spin coating method, and an ink jet method is particularly preferable. Further, different film forming methods may be applied for each layer. When employing a vapor deposition method 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., a vacuum degree of 10 ⁻⁶ to 10 ⁻² Pa, and a vapor deposition rate of 0.01 It is desirable to select appropriately within the range of ˜50 nm / second, substrate temperature −50 to 300 ° C., film thickness 0.1 nm to 5 μm, preferably 5 to 200 nm.

  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.

  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.

  When patterning is performed only on the light emitting layer, the method is not limited. However, 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.

  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.

  The multicolor display device of the present invention can be used as a display device, a display, or various light 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.

  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.

  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, light sources for optical sensors, etc. For example, but not limited to.

  Further, the organic EL element according to the present invention may be used as an organic EL element having a resonator structure.

  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.

<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.

  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.

  FIG. 1 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.

  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.

  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.

  FIG. 2 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. 2 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

  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).

  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.

  Next, the light emission process of the pixel will be described.

  FIG. 3 is a schematic diagram of a pixel.

  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.

  In FIG. 3, 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.

  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.

  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.

  That is, the organic EL element 10 emits light by the switching transistor 11 and the driving transistor 12 that are active elements for the organic EL elements 10 of the plurality of pixels, and the organic EL elements 10 of the plurality of pixels 3 emit light. It is carried out. Such a light emitting method is called an active matrix method.

  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.

  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.

  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.

  FIG. 4 is a schematic view of a passive matrix display device. In FIG. 4, 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.

  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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, the embodiment of this invention is not limited to these.

Example 1
An organic EL element was produced as follows. 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. Meanwhile, 200 mg of α-NPD is put into a molybdenum resistance heating boat, 200 mg of CBP is put into another resistance heating boat made of molybdenum, and another resistance made of molybdenum. 200 mg of bathocuproin (BCP) is put into a heating boat, 100 mg of phosphorescent compound Ir (ppy) ₃ is put into another resistance heating boat made of molybdenum, and 200 mg of Alq ₃ is put into another resistance heating boat made of molybdenum. Installed.

Next, the pressure in the vacuum chamber was reduced to 4 × 10 ⁻⁴ Pa, and the heating boat containing α-NPD was energized and heated, and deposited on the transparent support substrate at a deposition rate of 0.1 nm / sec. The hole transport layer was provided. Further, the heating boat containing CBP and the phosphorescent compound Ir (ppy) ₃ is energized and heated, and co-deposited on the hole transport layer at a deposition rate of 0.2 nm / sec and 0.012 nm / sec, respectively. A light emitting layer having a thickness of 35 nm was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature. Further, an electron transport layer that also serves as a hole blocking function with a film thickness of 10 nm is provided by energizing and heating the heating boat containing BCP and depositing on the light emitting layer at a deposition rate of 0.1 nm / sec. It was. Further, the heating boat containing Alq ₃ was further energized and heated, and was deposited on the electron transport layer at a deposition rate of 0.1 nm / sec to further provide an electron injection layer having a thickness of 40 nm. . In addition, the substrate temperature at the time of vapor deposition was room temperature.

  Then, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited, the cathode was formed, and the organic EL element OLED1-1 was produced. FIG. 5 is a sectional view thereof. Other organic EL elements shown in Table 1 were also produced in exactly the same manner except that the CBP of the light emitting layer was replaced with the compounds shown in Table 1. The structure of the compound used above is shown below.

<Evaluation of organic EL element>
Evaluation of the organic EL device produced as follows was performed, and the results are shown in Table 1.

(Luminance, luminous efficiency)
In the organic EL element OLED1-1, a current started to flow at an initial driving voltage of 3 V, and green light was emitted from the phosphorescent compound which is a dopant of the light emitting layer. The produced organic EL device was measured for light emission luminance (cd / m ² ) and light emission efficiency (lm / W) when a DC voltage of 10 V was applied at 23 ° C. in a dry nitrogen gas atmosphere. Luminance and luminous efficiency are expressed as relative values when the organic EL element OLED1-1 is 100. The light emission luminance was measured using CS-1000 (Minolta).

(durability)
The half-life time, which was the time required for the initial luminance to drop to half of the original luminance when driven at a constant current of ^2.5 mA / cm ² , was expressed as an index. The half-life time was expressed as a relative value when the organic EL element OLED1-1 was set to 100.

Example 2
An organic EL element OLED2-1 was produced in exactly the same manner except that the phosphorescent compound of the organic EL element OLED1-1 of Example 1 was replaced with FIr (pic). With respect to this element exhibiting blue light emission, light emission luminance and light emission efficiency were measured in the same manner as in Example 1. The obtained results are shown in Table 2 together with the organic EL device numbers and the compounds used in the light emitting layer.

Example 3
An organic EL device was produced in exactly the same manner except that the compound used in the electron transport layer of the organic EL device of Example 1 was replaced with the compound according to the present invention and the comparative compound from BCP. With respect to this organic EL element, light emission luminance, light emission efficiency, and durability were measured in the same manner as in Example 1. The obtained results are shown in Table 3 together with the organic EL element number and the compound used for the electron transport layer.

Example 4
The green and blue light-emitting organic EL elements prepared in the above examples and the red light-emitting organic EL elements prepared in the same manner except that the phosphorescent compound of the green light-emitting organic EL elements was replaced with Btp2Ir (acac) on the same substrate. Then, the active matrix type full-color display device shown in FIG. 1 was produced. FIG. 2 shows only a schematic diagram of the display portion A of the produced full-color display device. That is, a wiring portion including a plurality of scanning lines 5 and data lines 6 and a plurality of juxtaposed pixels 3 (light emission color is a red region pixel, a green region pixel, a blue region pixel, etc.) on the same substrate. Each of the scanning lines 5 and the plurality of data lines 6 in the wiring portion is 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). Is 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, full-color display is possible by appropriately juxtaposing the red, green, and blue pixels.

  By driving the full-color display device, a clear full-color moving image display with high luminance and good durability was obtained.

It is the schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of a display part. It is a schematic diagram of a pixel. It is a schematic diagram of a passive matrix type full-color display device. It is sectional drawing of the organic EL element 1-1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display 3 Pixel 5 Scan line 6 Data line 7 Power supply line 10 Organic EL element 11 Switching transistor 12 Drive transistor 13 Capacitor A Display part B Control part

Claims (5)

In an organic electroluminescent element having at least one light emitting layer, and light emission from the light emitting layer includes phosphorescence, a carbazole derivative represented by the following general formula 1 in any one of the layers constituting the organic electroluminescent element An organic electroluminescence device comprising a compound.

(In the formula, A represents an optionally substituted benzene ring, pyrimidine ring, triazine ring or dithienobenzene ring . R ₁ and R ₈ represent a hydrogen atom, and R ₂ , R ₄ , R ₅ and R _7. represents. However represent either hydrogen atoms, a alkylthio group, R _3, R ₆ is a hydrogen atom, a chlorine atom, a trifluoromethyl group, an amino group, an amide group, one cyano group or a heterocyclic group, R ₁ to R ₈ have greens be hydrogen atoms at the same time. n represents 2 or more natural number multiple of the carbazole derivative residue may be the same or different.) The organic electroluminescent device according to claim 1 , wherein the heterocyclic group represented by R ₃ or R ₆ in the general formula 1 is a thienyl group or a carbazolyl group . 3. The organic electroluminescence device according to claim 1, wherein A in formula 1 is a benzene ring, a pyrimidine ring or a triazine ring . The organic electroluminescent device according to any one of claims 1 to 3, wherein the light emitting layer contains a compound represented by the general formula 1. A display device comprising the organic electroluminescence element according to claim 1.

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