JP5708068B2 - ORGANIC ELECTROLUMINESCENT ELEMENT AND LIGHTING DEVICE - Google Patents

Description

  The present invention relates to an organic electroluminescence element and a lighting device applied to various displays, display devices, lighting, and the like.

  Surface light emitters used as backlights for various displays, display boards such as signboards and emergency lights, and light sources for lighting, etc. have attracted attention in recent years because they have many excellent features such as high brightness, high luminous efficiency, thinness, and light weight. Has been. Among such surface light emitters, an organic electroluminescence element (hereinafter also referred to as an organic EL element) that emits light by using electric energy from positive and negative electrodes using an organic material has a low voltage of about several volts to several tens of volts. In particular, it has been attracting attention in recent years because it is a thin-film type complete solid-state device and saves space.

  In order to increase the efficiency of organic EL elements, it is essential to improve the light extraction efficiency. However, since the distance between the light emitting layer and the metal electrode is close to the order of several tens of nanometers, the waveguide loss of surface plasmon mode light is reduced. There is a problem that the light extraction efficiency does not increase. As a means for reducing the waveguide loss of the surface plasmon mode light, a top emission type configuration can be cited.

  As one of the problems of the top emission type organic EL element, there are a reduction in light emission efficiency, a drive voltage increase, and a decrease in life due to damage to the organic layer in the process of forming the transparent conductive layer. In particular, when the sputtering method with high productivity is used as the film forming process of the transparent conductive layer, the above-mentioned problem becomes remarkable, and the compatibility between the productivity and the element characteristics of the top emission type organic EL element is a big problem.

  For example, as a cause of damage to the organic layer when ITO is formed by sputtering, the organic layer is oxidized by oxygen radicals or ITO particles as a target component are implanted into the organic layer (hereinafter referred to as ITO particle implantation). For example).

  As a technique for suppressing organic layer damage in the sputtering process, a technique in which a layer made of a metal phthalocyanine-based material such as copper phthalocyanine (hereinafter referred to as a sputter buffer layer) is considered between the cathode electrode and the light emitting layer. (See Patent Documents 1 to 4). This technique has a drawback that the luminous efficiency is lowered because copper phthalocyanine having a low transmittance is used as the material of the sputter buffer layer. In particular, with respect to deterioration due to the implantation of ITO particles, it is necessary to increase the film thickness of the sputter buffer layer, and thus the above-described decrease in light emission efficiency becomes more remarkable.

JP 2000-58265 A JP 2000-68063 A JP 2004-14511 A JP 2006-228573 A

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic electroluminescence element and a lighting device having high light emission efficiency and low driving voltage.

  The above object of the present invention is achieved by the following configurations.

1. In an organic electroluminescence element in which an anode electrode, a light emitting layer, and a cathode electrode are laminated in this order on one main surface of a substrate, the cathode electrode is formed by disposing a transparent conductive layer and a metal oxide semiconductor from a side far from the light emitting layer. And a layer doped with an element belonging to Group 1 or Group 2 of the periodic table and a metal layer are laminated in this order. The element belonging to the group has a standard electrode potential of -3.00 V vs. metal ion (M ^{n +} ) / metal (M) system. An organic electroluminescence device characterized in that it is a metal or a metal compound of a noble element than SHE, and the light emitting layer contains a phosphorescent compound.

  2. 2. The organic electroluminescence device according to 1 above, wherein the metal oxide semiconductor is molybdenum oxide, rhenium oxide, or nickel oxide.

  3. 3. The organic electroluminescence device as described in 1 or 2 above, wherein the element belonging to Group 1 or Group 2 of the periodic table is potassium.

  4). The total thickness of the layer having the metal oxide semiconductor and the layer doped with an element belonging to Group 1 or Group 2 of the periodic table is 100 nm to 200 nm. Organic electroluminescent element of any one of these.

  5. The ratio between the thickness of the layer having the metal oxide semiconductor and the thickness of the layer doped with an element belonging to Group 1 or Group 2 of the periodic table is in the range of 1:10 to 1:20. 5. The organic electroluminescence device according to any one of 1 to 4 above.

  6). Any one of 1 to 5 above, wherein the main component of the layer doped with an element belonging to Group 1 or Group 2 of the periodic table has a compound represented by the following general formula (1): The organic electroluminescent element of description.

General formula (1)
(Ar1) n1-Y1
[Wherein, n1 represents an integer of 1 or more, Y1 represents a substituent when n1 is 1, and represents a mere bond or an n1-valent linking group when n1 is 2 or more. Ar1 represents a group represented by the following general formula (A). When n1 is 2 or more, a plurality of Ar1s may be the same or different. However, the compound represented by the general formula (1) has at least two condensed aromatic heterocycles in which three or more rings are condensed in the molecule. ]

[Wherein, X represents -N (R)-, -O-, -S- or -Si (R) (R ')-, and E1-E8 represents -C (R1) = or -N = R, R ′ and R1 represent a hydrogen atom, a substituent or a linking site with Y1. * Represents a linking site with Y1. Y2 represents a simple bond or a divalent linking group. Y3 and Y4 each represent a group derived from a 5-membered or 6-membered aromatic ring, and at least one represents a group derived from an aromatic heterocycle containing a nitrogen atom as a ring constituent atom. n2 represents an integer of 1 to 4. ]
7). 7. The organic electroluminescence device as described in 6 above, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

[Wherein Y5 represents a divalent linking group comprising an arylene group, a heteroarylene group, or a combination thereof. E51 to E66 each represent -C (R3) = or -N =, and R3 represents a hydrogen atom or a substituent. Y6 to Y9 each represents a group derived from an aromatic hydrocarbon ring or a group derived from an aromatic heterocycle, and at least one of Y6 or Y7 and at least one of Y8 or Y9 is an aromatic group containing an N atom. Represents a group derived from a group heterocycle. n3 and n4 represent an integer of 0 to 4, but n3 + n4 is an integer of 2 or more. ]
8). 7. The organic electroluminescence device as described in 6 above, wherein the compound represented by the general formula (1) is a compound represented by the following general formula (3).

[Wherein Y5 represents a divalent linking group comprising an arylene group, a heteroarylene group, or a combination thereof. E51 to E66 and E71 to E88 each represent -C (R3) = or -N =, and R3 represents a hydrogen atom or a substituent. However, at least one of E71 to E79 and at least one of E80 to E88 represents -N =. n3 and n4 represent an integer of 0 to 4, but n3 + n4 is an integer of 2 or more. ]
9. 9. The organic electroluminescence device according to any one of 1 to 8, wherein the phosphorescent compound is a compound represented by the following general formula (4).

[Wherein, P and Q each represent a carbon atom or a nitrogen atom, and A1 represents an atomic group which forms an aromatic hydrocarbon ring or an aromatic heterocycle together with PC. A2 represents an atomic group which forms an aromatic heterocycle with QN. P1-L1-P2 represents a bidentate ligand, and P1 and P2 each independently represent a carbon atom, a nitrogen atom, or an oxygen atom. L1 represents an atomic group that forms a bidentate ligand together with P1 and P2. j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, and j1 + j2 is 2 or 3. M1 represents a group 8-10 transition metal element in the periodic table. ]
10. 10. The organic electroluminescence device as described in 9 above, wherein the compound represented by the general formula (4) is a compound represented by the following general formula (5).

[Wherein Z represents a hydrocarbon ring group or a heterocyclic group. P and Q each represent a carbon atom or a nitrogen atom, and A1 represents an atomic group that forms an aromatic hydrocarbon ring or an aromatic heterocyclic ring together with PC. A3 represents -C (R01) = C (R02)-, -N = C (R02)-, -C (R01) = N- or -N = N-, and each of R01 and R02 represents a hydrogen atom or a substituent. Represents a group. P1-L1-P2 represents a bidentate ligand, and P1 and P2 each independently represent a carbon atom, a nitrogen atom, or an oxygen atom. L1 represents an atomic group that forms a bidentate ligand together with P1 and P2. j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, and j1 + j2 is 2 or 3. M1 represents a group 8-10 transition metal element in the periodic table. ]
11. Said M1 represents iridium, The said organic electroluminescent element of 9 or 10 characterized by the above-mentioned.

  12 12. The organic electroluminescence element according to any one of 1 to 11, wherein an auxiliary electrode is provided on the transparent conductive layer.

  13. The organic electroluminescence element according to any one of 1 to 12, wherein the organic electroluminescence element is a double-sided emission type.

  14 14. An illumination device comprising the organic electroluminescence element according to any one of 1 to 13 above.

  According to the present invention, it was possible to provide an organic electroluminescence element and a lighting device with high luminous efficiency and low driving voltage.

It is an example which shows the structure of the organic electroluminescent element which has a cathode electrode laminated | stacked on four layers. It is a schematic perspective view which shows an example of the illuminating device using the organic EL element of this invention. It is a schematic sectional drawing which shows an example of the illuminating device using the organic EL element of this invention.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

The organic electroluminescent element of the present invention has a cathode electrode laminated in four layers and a light emitting layer containing a phosphorescent compound. The four layers of the cathode electrode are arranged in this order: a transparent conductive layer, a layer having a metal oxide semiconductor, a layer doped with an element belonging to Group 1 or 2 of the periodic table, and a metal layer in this order. The element belonging to Group 1 or Group 2 of the periodic table has a standard electrode potential of metal ion (M ^{n +} ) / metal (M) system of −3.00 Vvs. It is a metal or metal compound of an element more precious than SHE.

  The cathode electrode laminated in four layers according to the present invention is a transparent conductive layer that is made of a transparent conductive layer to reduce the thickness of the metal layer and increase the transmittance of the device. Target particle implantation, which is a problem when forming a layer, is prevented by increasing the thickness of a layer doped with an element belonging to Group 1 or Group 2 of the periodic table, such as sputtering. By suppressing the oxygen radical with a layer having a metal oxide semiconductor, in making an organic electroluminescent device using a light emitting layer containing a phosphorescent compound, without damaging the organic layer, A cathode electrode with high transmittance can be formed.

  Hereinafter, the organic electroluminescence element of the present invention will be described.

《Organic electroluminescence device》
First, embodiments of the organic EL device of the present invention, which is an example of a surface light emitter, will be described in detail. The contents described below are representative examples of embodiments of the present invention, and the present invention exceeds the gist thereof. As long as there is no, it is not limited to these contents.

  First, the preferable specific example of the layer structure of an organic EL element is shown below.

(I) Anode electrode / light emitting layer / electron transport layer / electron injection layer / cathode electrode (metal layer / layer doped with elements belonging to Group 1 or Group 2 of the periodic table / layer having a metal oxide semiconductor / Transparent conductive layer)
(Ii) Anode electrode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode electrode (metal layer / layer doped with elements belonging to Group 1 or Group 2 of the periodic table / metal oxide) Semiconductor layer / transparent conductive layer)
(Iii) Anode electrode / hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode electrode (metal layer / elements belonging to Group 1 or Group 2 of the periodic table are doped) Layer / metal oxide semiconductor layer / transparent conductive layer)
In the organic EL device of the present invention, the cathode electrode is preferably transparent, and the opposing electrode can be selected to be either transparent or opaque depending on the application. The organic EL device of the present invention preferably has a top emission type or double side emission type configuration.

  The light emitting layer preferably contains at least two kinds of light emitting materials having different emission colors, and a single layer or a light emitting layer unit composed of a plurality of light emitting layers may be formed. The hole transport layer also includes a hole injection layer and an electron blocking layer.

《Cathode electrode》
The cathode electrode of the present invention (hereinafter also referred to as cathode) is a transparent conductive layer, a layer having a metal oxide semiconductor, a layer doped with an element belonging to Group 1 or Group 2 of the periodic table, from the far side of the light emitting layer, Four layers of metal layers are laminated in order, and an element belonging to Group 1 or Group 2 of the periodic table has a standard electrode potential of metal ion (M ^{n +} ) / metal (M) system of −3.00 Vvs. It is characterized by being a metal or a metal compound of an element more precious than SHE.

  Hereafter, each layer of the laminated 4 layer structure which comprises the cathode of this invention is demonstrated. In addition, the cathode of the present invention may be further provided outside the transparent conductive layer and the metal layer as necessary, or the transparent conductive layer, the layer having a metal oxide semiconductor, the periodic table group 1 or Each of the layer doped with an element belonging to Group 2 and the metal layer may be composed of a plurality of layers.

<Transparent conductive layer>
As the transparent conductive layer constituting the cathode of the present invention, a conductive light transmissive material such as indium tin oxide (ITO), SnO ₂ or ZnO is preferably used. Alternatively, a material such as IDIXO (In ₂ O ₃ —ZnO) that can form an amorphous light-transmitting conductive film may be used. As a method for forming the transparent conductive layer of the present invention, a sputtering method is preferable from the viewpoint of productivity. If necessary, the transparent conductive layer of the present invention may form a pattern having a desired shape by a photolithography method, or when the pattern accuracy is not so high (about 100 μm or more), the electrode material is deposited. Alternatively, a pattern may be formed through a mask having a desired shape during sputtering. The sheet resistance of the transparent conductive layer of the present invention 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 50 to 200 nm.

<< Layer with Metal Oxide Semiconductor >>
The layer having a metal oxide semiconductor constituting the cathode of the present invention is preferably formed by vapor deposition. Although there is no restriction | limiting in particular as a metal oxide, The metal oxide which consists of a metal selected from the transition metal or the rare earth metal can be used. A preferred compound as the metal oxide of the present invention is molybdenum oxide, rhenium oxide or nickel oxide. The metal oxide of the present invention is more preferably in an oxygen defect state. The oxygen defect state of the present invention refers to a state having an oxygen-deficient non-stoichiometric composition.

  The ratio of the film thickness of the layer having the metal oxide semiconductor of the present invention to the film thickness of a layer doped with an element belonging to Group 1 or Group 2 of the periodic table described later is in the range of 1:10 to 1:20. It is preferable that it exists in. The main purpose of the layer having a metal oxide semiconductor of the present invention is to suppress oxidation of elements belonging to Group 1 or Group 2 of the periodic table due to oxygen radicals generated during the formation of the transparent conductive layer. The film thickness may be the minimum necessary. If an element belonging to Group 1 or Group 2 of the periodic table is oxidized, the electron transport property of the layer doped with the element belonging to Group 1 or Group 2 of the periodic table is deteriorated and the voltage is increased. Providing the layer having the metal oxide semiconductor of the present invention between the transparent conductive layer and the layer doped with an element belonging to Group 1 or Group 2 of the periodic table is extremely effective in achieving the effects of the present invention. is important.

<< Layer doped with elements belonging to Group 1 or Group 2 of the periodic table >>
The layer doped with an element belonging to Group 1 or Group 2 of the periodic table constituting the cathode of the present invention is preferably formed by vapor deposition. The element belonging to Group 1 or Group 2 of the periodic table of the present invention has a standard electrode potential of −3.00 V vs. metal ion (M ^{n +} ) / metal (M) system. It is characterized by being a metal or a metal compound of an element more precious than SHE. Here, the standard electrode potential E ° of the Mn + / M system according to the present invention is an electrode potential with respect to a standard hydrogen electrode in an aqueous solution having a temperature of 25 ° C. and an solute activity of all 1. For example, “Revised Third Edition You can refer to the values in Tables 12 and 46, page II-474 of “Chemical Handbook II” (The Chemical Society of Japan). According to the present invention, the element belongs to Group 1 or Group 2 of the periodic table, and the standard electrode potential of the metal ion (M ^{n +} ) / metal (M) system of the element is −3.00 Vvs. Specific examples of elements constituting a metal or metal compound of an element more precious than SHE include potassium (-2.925 (V)), calcium (-2.840 (V)), and sodium (-2. 714 (V)), magnesium (-2.356 (V)), and the like.

  A preferred element as an element belonging to Group 1 or Group 2 of the periodic table of the present invention is potassium. Elements whose standard electrode potential is lower than -3V, such as cesium (-3.027 (V)) and lithium (-3.045 (V)), have the effect of improving the electron transport property, but they themselves Since it is easily oxidized, it has a defect of low production compatibility.

  The doping amount of elements belonging to Group 1 or Group 2 of the periodic table of the present invention is 1% to 50% by mass with respect to the total mass of the layer doped with elements belonging to Group 1 or Group 2 of the Periodic Table It is preferable to be in a ratio. A more preferable range of the doping amount of elements belonging to Group 1 or Group 2 of the periodic table of the present invention is 5% to 20%.

  The main component of the layer doped with an element belonging to Group 1 or Group 2 of the periodic table of the present invention is preferably a compound represented by the following general formulas (1) to (3). A main component means the component contained 50 mass% or more with respect to the total mass of a layer. More preferably, the doping amount of the element belonging to Group 1 or Group 2 of the periodic table is 5% to 20% with respect to the total mass of the doped layer, and the rest is represented by the following general formulas (1) to (3) It is that it is a compound represented by these.

<< Compound Represented by Formula (1) >>
The compound represented by the general formula (1) according to the present invention will be described.

  In the general formula (1), examples of the substituent represented by Y1 include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl 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 ethynyl group, propargyl etc.) Group), aromatic hydrocarbon group (also called aromatic carbocyclic group, aryl group, etc.), for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, Acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, biphenyl Group), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group, carbazolyl group, carbolinyl group) , A diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), a phthalazinyl group, etc.), a heterocyclic group (eg, pyrrolidyl group, imidazolidyl group) , Morpholyl group, oxazolidyl group, etc.), alkoxy group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy group (eg, cyclopentyloxy group) Group, cyclohexyloxy group, etc. , Aryloxy groups (for example, phenoxy group, naphthyloxy group, etc.), alkylthio groups (for example, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio groups (for example, Cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.), alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyl) Oxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfur group) (Honyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.) An 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, octylcarbonyloxy group, Silcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexyl) Carbonylamino 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, dodecylamino Carbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, Phenylureido group naphthylureido group, 2-pyridylaminoureido 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 (for example, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group) Cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group etc.), arylsulfonyl group or heteroarylsulfonyl group (eg phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group etc.), amino group (eg amino Group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, piperidyl group (also called piperidinyl group), 2 , 2,6,6-tetramethylpiperidinyl group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, penta) Fluoroethyl group, penta Urophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (eg, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.), phosphate ester group (eg, dihexyl) Phosphoryl group, etc.), phosphite group (for example, diphenylphosphinyl group, etc.), phosphono group and the like.

  These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

  Specific examples of the n1-valent linking group represented by Y1 in the general formula (1) include a divalent linking group, a trivalent linking group, and a tetravalent linking group.

  In the general formula (1), as the divalent linking group represented by Y1, an alkylene group (for example, ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, hexamethylene group, 2,2,4-trimethylhexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, cyclohexylene group (for example, 1,6-cyclohexanediyl group, etc.), Cyclopentylene group (for example, 1,5-cyclopentanediyl group and the like), alkenylene group (for example, vinylene group, propenylene group, butenylene group, pentenylene group, 1-methylvinylene group, 1-methylpropenylene group, 2-methylpropenylene group, 1-methylpentenylene group, 3-methyl Ntenylene group, 1-ethylvinylene group, 1-ethylpropenylene group, 1-ethylbutenylene group, 3-ethylbutenylene group, etc.), alkynylene group (for example, ethynylene group, 1-propynylene group, 1-butynylene group, 1-pentynylene group) 1-hexynylene group, 2-butynylene group, 2-pentynylene group, 1-methylethynylene group, 3-methyl-1-propynylene group, 3-methyl-1-butynylene group, etc.), arylene group (for example, o-phenylene group) , P-phenylene group, naphthalenediyl group, anthracenediyl group, naphthacenediyl group, pyrenediyl group, naphthylnaphthalenediyl group, biphenyldiyl group (for example, [1,1′-biphenyl] -4,4′-diyl group, 3, 3′-biphenyldiyl group, 3,6-biphenyldiyl group, etc.), terf Nildiyl group, quaterphenyldiyl group, kinkphenyldiyl group, sexiphenyldiyl group, septiphenyldiyl group, octiphenyldiyl group, nobiphenyldiyl group, deciphenyldiyl group, etc.), heteroarylene group (for example, carbazole) Ring, carboline ring, diazacarbazole ring (also called monoazacarboline ring, which shows a ring structure in which one of carbon atoms constituting carboline ring is replaced by nitrogen atom), triazole ring, pyrrole ring, pyridine ring, pyrazine Ring, quinoxaline ring, thiophene ring, oxadiazole ring, dibenzofuran ring, dibenzothiophene ring, divalent group derived from the group consisting of indole ring, etc.), chalcogen atom such as oxygen and sulfur, 3 or more rings Groups derived from condensed aromatic heterocycles formed by condensation (this Here, the condensed aromatic heterocyclic ring formed by condensing three or more rings is preferably an aromatic heterocyclic ring containing a hetero atom selected from N, O and S as an element constituting the condensed ring. Specifically, acridine ring, benzoquinoline ring, carbazole ring, phenazine ring, phenanthridine ring, phenanthroline ring, carboline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrin ring, triphenodithia Gin ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (representing any one of carbon atoms constituting carboline ring replaced by nitrogen atom), phenanthroline ring, dibenzofuran Ring, dibenzothiophene ring, naphthofuran ring, naphthothiophene ring, Nzodifuran ring, benzodithiophene ring, naphthodifuran ring, naphthodithiophene ring, anthrafuran ring, anthradifuran ring, anthrathiophene ring, anthradithiophene ring, thianthrene ring, phenoxathiin ring, thiophanthrene ring (naphthothiophene ring) ) Etc.).

  In the general formula (1), examples of the trivalent linking group represented by Y1 include ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, and octanetriyl. Group, nonanetriyl group, decanetriyl group, undecanetriyl group, dodecanetriyl group, cyclohexanetriyl group, cyclopentanetriyl group, benzenetriyl group, naphthalenetriyl group, pyridinetriyl group, carbazoletriyl group, etc. Can be mentioned.

  In the general formula (1), as the tetravalent linking group represented by Y1, one trivalent group is added to the above trivalent group, and examples thereof include a propanediylidene group and 1,3-propane. Diyl-2-ylidene group, butanediylidene group, pentanediylidene group, hexanediylidene group, heptanediylidene group, octanediylidene group, nonanediylidene group, decandiylidene group, undecandiylidene group, dodecandiylidene group, cyclohexanediylidene group , Cyclopentanediylidene group, benzenetetrayl group, naphthalenetetrayl group, pyridinetetrayl group, carbazoletetrayl group and the like.

  The divalent linking group, the trivalent linking group, and the tetravalent linking group may each further have a substituent represented by Y1 in the general formula (1).

  As a preferred embodiment of the compound represented by the general formula (1), Y1 preferably represents a group derived from a condensed aromatic heterocyclic ring formed by condensation of three or more rings, and the three or more rings. As the condensed aromatic heterocyclic ring formed by condensing, a dibenzofuran ring or a dibenzothiophene ring is preferable. Further, n1 is preferably 2 or more.

  Furthermore, the compound represented by the general formula (1) has at least two condensed aromatic heterocycles obtained by condensing the above three or more rings in the molecule.

  When Y1 represents an n1-valent linking group, Y1 is preferably non-conjugated in order to keep the triplet excitation energy of the compound represented by the general formula (1) high, and further, Tg (glass transition In view of improving the point, also referred to as glass transition temperature, it is preferably composed of an aromatic ring (aromatic hydrocarbon ring + aromatic heterocycle).

  Here, the term “non-conjugated” means that the linking group cannot be expressed by repeating a single bond (also referred to as a single bond) and a double bond, or the conjugation between aromatic rings constituting the linking group is sterically cleaved. Means.

(Group represented by general formula (A))
In the general formula (1), Ar1 represents a group represented by the general formula (A).

  In —N (R) — or —Si (R) (R ′) — represented by X in the general formula (A), R, R in —C (R1) ═ represented by E1 to E8 The substituent represented by each 'and R1 has the same meaning as the substituent represented by Y1 in the general formula (1).

  In the general formula (A), the divalent linking group represented by Y2 has the same meaning as the divalent linking group represented by Y1 in the general formula (1).

  In the general formula (A), a 5-membered or 6-membered aromatic ring used for forming a group derived from a 5-membered or 6-membered aromatic ring represented by Y3 and Y4, respectively, includes a benzene ring, oxazole Examples include a ring, a thiophene ring, a furan ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a diazine ring, a triazine ring, an imidazole ring, an isoxazole ring, a pyrazole ring, and a triazole ring.

  Furthermore, at least one of the groups derived from a 5-membered or 6-membered aromatic ring represented by Y3 and Y4 respectively represents a group derived from an aromatic heterocycle containing a nitrogen atom as a ring-constituting atom, As the aromatic heterocycle containing a nitrogen atom as the ring constituent atom, an oxazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a diazine ring, a triazine ring, an imidazole ring, an isoxazole ring, a pyrazole ring, Examples include a triazole ring.

(Preferred embodiment of the group represented by Y3)
In the general formula (A), the group represented by Y3 is preferably a group derived from the above 6-membered aromatic ring, and more preferably a group derived from a benzene ring.

(Preferred embodiment of the group represented by Y4)
In general formula (A), the group represented by Y4 is preferably a group derived from the 6-membered aromatic ring, more preferably an aromatic heterocycle containing a nitrogen atom as a ring constituent atom. Particularly preferably, Y4 is a group derived from a pyridine ring.

(Preferred embodiment of the group represented by the general formula (A))
As a preferable aspect of group represented by general formula (A), group represented by either the following general formula (A-1), (A-2), (A-3) or (A-4) Is mentioned.

  In the formula, X represents —N (R) —, —O—, —S— or —Si (R) (R ′) —, E1 to E8 represent —C (R1) ═ or —N═, R, R ′, and R1 each represent a hydrogen atom, a substituent, or a linking site with Y1. Y2 represents a simple bond or a divalent linking group. E11 to E20 represent -C (R2) = or -N =, and at least one represents -N =. R2 represents a hydrogen atom, a substituent or a linking site. However, at least one of E11 and E12 represents -C (R2) =, and R2 represents a linking site. n2 represents an integer of 1 to 4. * Represents a linking site with Y1 in the general formula (1).

  In the formula, X represents —N (R) —, —O—, —S— or —Si (R) (R ′) —, E1 to E8 represent —C (R1) ═ or —N═, R, R ′, and R1 each represent a hydrogen atom, a substituent, or a linking site with Y1. Y2 represents a simple bond or a divalent linking group. E21 to E25 represent -C (R2) = or -N =, and E26 to E30 represent -C (R2) =, -N =, -O-, -S- or -Si (R3) (R4)-. And at least one of E21 to E30 represents -N =. R2 represents a hydrogen atom, a substituent or a linking site, and R3 and R4 represent a hydrogen atom or a substituent. However, at least one of E21 or E22 represents -C (R2) =, and R2 represents a linking site. n2 represents an integer of 1 to 4. * Represents a linking site with Y1 in the general formula (1).

  In the formula, X represents —N (R) —, —O—, —S— or —Si (R) (R ′) —, E1 to E8 represent —C (R1) ═ or —N═, R, R ′, and R1 each represent a hydrogen atom, a substituent, or a linking site with Y1. Y2 represents a simple bond or a divalent linking group. E31 to E35 represent -C (R2) =, -N =, -O-, -S- or -Si (R3) (R4)-, and E36 to E40 represent -C (R2) = or -N =. And at least one of E31 to E40 represents -N =. R2 represents a hydrogen atom, a substituent or a linking site, and R3 and R4 represent a hydrogen atom or a substituent. However, at least one of E32 or E33 is represented by -C (R2) =, and R2 represents a linking site. n2 represents an integer of 1 to 4. * Represents a linking site with Y1 in the general formula (1).

  In the formula, X represents —N (R) —, —O—, —S— or —Si (R) (R ′) —, E1 to E8 represent —C (R1) ═ or —N═, R, R ′, and R1 each represent a hydrogen atom, a substituent, or a linking site with Y1. Y2 represents a simple bond or a divalent linking group. E41 to E50 represent -C (R2) =, -N =, -O-, -S-, or -Si (R3) (R4)-, and at least one represents -N =. R2 represents a hydrogen atom, a substituent or a linking site, and R3 and R4 represent a hydrogen atom or a substituent. However, at least one of E42 or E43 is represented by -C (R2) =, and R2 represents a linking site. n2 represents an integer of 1 to 4. * Represents a linking site with Y1 in the general formula (1).

  Hereinafter, the group represented by any one of the general formulas (A-1) to (A-4) will be described.

  In -N (R)-or -Si (R) (R ')-represented by X of any of the groups represented by formulas (A-1) to (A-4), E1 to In —C (R1) ═ represented by E8, the substituent represented by each of R, R ′, and R1 has the same meaning as the substituent represented by Y1 in General Formula (1).

  In any of the groups represented by the general formulas (A-1) to (A-4), the divalent linking group represented by Y2 is a divalent group represented by Y1 in the general formula (1). It is synonymous with the linking group.

  E11 to E20 of the general formula (A-1), E21 to E30 of the general formula (A-2), E31 to E40 of the general formula (A-3), E41 to E50 of the general formula (A-4), respectively. The substituent represented by R2 in —C (R2) ═ is synonymous with the substituent represented by Y1 in General Formula (1).

  Next, the further preferable aspect of the compound represented by General formula (1) based on this invention is demonstrated.

<< Compound Represented by Formula (2) >>
In this invention, the compound represented by the said General formula (2) is preferable among the compounds represented by the said General formula (1). Hereinafter, the compound represented by the general formula (2) will be described.

  In general formula (2), the arylene group and heteroarylene group represented by Y5 are the arylene group and heteroarylene group described as an example of the divalent linking group represented by Y1 in general formula (1). Are synonymous with each other.

  As a preferred embodiment of the divalent linking group comprising an arylene group, a heteroarylene group or a combination thereof represented by Y5, among the heteroarylene groups, a condensed aromatic heterocycle formed by condensation of three or more rings. A group derived from a condensed aromatic heterocycle formed by condensation of three or more rings is preferably included, and the group derived from a dibenzofuran ring or a dibenzothiophene ring is preferable. Are preferred.

  In General Formula (2), the substituent represented by R3 of —C (R3) ═ represented by E51 to E66 has the same meaning as the substituent represented by Y1 in General Formula (1).

  In the general formula (2), as groups represented by E51 to E66, 6 or more of E51 to E58 and 6 or more of E59 to E66 are each represented by -C (R3) =. It is preferable.

  In the general formula (2), Y6 to Y9 are each an aromatic hydrocarbon ring used for forming a group derived from an aromatic hydrocarbon ring, such as a benzene ring, a biphenyl ring, a naphthalene ring, an azulene ring, an anthracene ring. Phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring , Pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, anthraanthrene ring, and the like.

  Further, the aromatic hydrocarbon ring may have a substituent represented by Y1 in the general formula (1).

  In the general formula (2), Y6 to Y9 are each an aromatic heterocycle used for forming a group derived from an aromatic heterocycle, for example, a furan ring, a thiophene ring, an oxazole ring, a pyrrole ring, or a pyridine ring. , Pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole Ring, quinoxaline ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring (one of the carbon atoms constituting the carboline ring is further substituted with a nitrogen atom) To indicate the ring It is.

  Further, the aromatic hydrocarbon ring may have a substituent represented by Y1 in the general formula (1).

  In the general formula (2), an aromatic heterocycle containing an N atom used for forming a group derived from an aromatic heterocycle containing an N atom represented by at least one of Y6 or Y7 and at least one of Y8 or Y9. Examples of the ring include, for example, an oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, Indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine ring, carbazole ring, carboline ring, diazacarbazole ring ( Construct carboline ring One of the carbon atoms can be mentioned further shows a ring substituted with a nitrogen atom) or the like.

  In the general formula (2), the groups represented by Y7 and Y9 each preferably represent a group derived from a pyridine ring.

  Moreover, in General formula (2), it is preferable that each group represented by Y6 and Y8 represents a group derived from a benzene ring.

  Furthermore, a more preferable aspect is demonstrated among the compounds represented by General formula (2) based on this invention.

<< Compound Represented by Formula (3) >>
In the present invention, among the compounds represented by the general formula (2), a compound represented by the general formula (3) is more preferable. Hereinafter, the compound represented by the general formula (2) will be described.

  In general formula (3), the arylene group and heteroarylene group represented by Y5 are the arylene group and heteroarylene group described as an example of the divalent linking group represented by Y1 in general formula (1). Are synonymous with each other.

  As a preferred embodiment of the divalent linking group comprising an arylene group, a heteroarylene group or a combination thereof represented by Y5, among the heteroarylene groups, a condensed aromatic heterocycle formed by condensation of three or more rings. A group derived from a condensed aromatic heterocycle formed by condensation of three or more rings is preferably included, and the group derived from a dibenzofuran ring or a dibenzothiophene ring is preferable. Are preferred.

  In the general formula (3), the substituent represented by R3 of —C (R3) ═ represented by E51 to E66 and E71 to E78 is the same as the substituent represented by Y1 in the general formula (1). It is synonymous.

  In general formula (3), it is preferable that 6 or more of E51 to E58 and 6 or more of E59 to E66 are each represented by -C (R3) =.

  In the general formula (3), it is preferable that at least one of E75 to E79 and at least one of E84 to E88 represent -N =.

  Furthermore, in General formula (3), it is preferable that any one of E75-E79 and any one of E84-E88 represent -N =.

  Moreover, in General formula (3), it is mentioned as a preferable aspect that E71-E74 and E80-E83 are each represented by -C (R3) =.

  Further, in the compound represented by the general formula (2) or the general formula (3), it is preferable that E53 is represented by -C (R3) = and R3 represents a linking site, and E61 is also simultaneously- It is preferably represented by C (R3) = and R3 represents a linking site.

  Further, E75 and E84 are preferably represented by -N =, and E71 to E74 and E80 to E83 are each preferably represented by -C (R3) =.

  Hereinafter, although the specific example of a compound represented by General formula (1), (2) or (3) based on this invention is shown, this invention is not limited to these.

  Although the synthesis example of a typical compound is shown below, this invention is not limited to these.

  << Synthesis Example of Compound 5 >>

Step 1: (Synthesis of Intermediate 1)
Under a nitrogen atmosphere, 3,6-dibromodibenzofuran (1.0 mol), carbazole (2.0 mol), copper powder (3.0 mol) and potassium carbonate (1.5 mol) in 300 ml of DMAc (dimethylacetamide) And stirred at 130 ° C. for 24 hours. After cooling the reaction solution to room temperature, 1 l of toluene was added and washed 3 times with distilled water. The organic layer was evaporated under reduced pressure, and the residue was subjected to silica gel flash chromatography (n-heptane: toluene = 4: 1 to 1). 3: 1) to obtain Intermediate 1 in a yield of 85%.

Step 2: (Synthesis of Intermediate 2)
Intermediate 1 (0.5 mol) was dissolved in 100 ml of DMF at room temperature under air, NBS (2.0 mol) was added, and the mixture was stirred overnight at room temperature. The resulting precipitate was filtered and washed with methanol, yielding intermediate 2 in 92% yield.

Step 3: (Synthesis of Compound 5)
Under a nitrogen atmosphere, intermediate 2 (0.25 mol), 2-phenylpyridine (1.0 mol), ruthenium complex [(η ₆ -C ₆ H ₆ ) RuCl ₂ ] ₂ (0.05 mol), triphenyl Phosphine (0.2 mol) and potassium carbonate (12 mol) were mixed in 3 l of NMP (N-methyl-2-pyrrolidone) and stirred at 140 ° C. overnight.

After cooling the reaction solution to room temperature, 5 l of dichloromethane was added and the reaction solution was filtered. The filtrate was distilled off the solvent under reduced pressure (800 Pa, 80 ° C.), and the residue (N-methyl-2-pyrrolidone) was subjected to silica gel flash chromatography (CH ₂ Cl ₂ : Et ₃ N = 20: 1 to 10: 1). It refine | purified in.

  Each fraction was collected and the solvent was distilled off under reduced pressure. The residue was redissolved in dichloromethane and washed three times with water. The organic phase was dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure to obtain Compound 5 in a yield of 68%.

  The total thickness of the layer having the metal oxide semiconductor of the present invention and the layer doped with an element belonging to Group 1 or Group 2 of the periodic table is preferably 100 nm or more and 200 nm or less. By increasing the film thickness to 100 nm or more, the effect of suppressing a problem such as a short circuit due to implantation of a target component such as ITO particles, which is one of the problems when forming the transparent conductive layer, is increased. In particular, a layer doped with an element belonging to Group 1 or Group 2 of the periodic table has a high electron transporting property, so there is little voltage increase even when the film thickness is increased. It is preferable to reduce the thickness of the layer including the metal oxide semiconductor and increase the thickness of the layer doped with an element belonging to Group 1 or Group 2 of the periodic table.

《Metallic layer》
The metal layer constituting the cathode of the present invention is preferably formed by vapor deposition. The material for forming the metal layer is not particularly limited, but is preferably selected from one or more of aluminum, magnesium, calcium, lithium, silver, gold, and alloys thereof. The thickness of the metal layer of the present invention is preferably in the range of 1 nm to 10 nm from the viewpoint of increasing the transmittance of the cathode, and more preferably in the range of 1 nm to 5 nm.

《Auxiliary electrode》
In the organic EL device of the present invention, an auxiliary electrode can be provided on the transparent conductive layer for the purpose of reducing the resistance. As a material for forming the auxiliary electrode, a metal having low resistance such as gold, platinum, silver, copper, and aluminum is preferable. Examples of the method for forming the auxiliary electrode include a vapor deposition method, a sputtering method, a printing method, an ink jet method, and an aerosol jet method. The line width of the auxiliary electrode of the present invention is preferably 50 μm or less from the viewpoint of the aperture ratio of the transparent conductive layer, and the thickness of the auxiliary electrode is preferably 1 μ or more from the viewpoint of conductivity.

[Light emitting layer]
The light emitting layer of the present invention is characterized by containing a phosphorescent compound as a light emitting material.

  The light-emitting layer 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. It may be an interface with an adjacent layer.

  As a light emitting layer, if the light emitting material contained satisfies the light emission requirement, there will be no restriction | limiting in particular in the structure. Moreover, there may be a plurality of layers having the same emission spectrum and emission maximum wavelength. Moreover, it is preferable to have a non-light emitting intermediate | middle layer between each light emitting layer.

  The total thickness of the light emitting layers is preferably in the range of 1 to 100 nm, and more preferably 1 nm or more and 30 nm or less because a lower driving voltage can be obtained. Note that the total film thickness of the light emitting layer is a film thickness including the intermediate layer when a non-light emitting intermediate layer exists between the light emitting layers.

  The thickness of each light emitting layer is preferably adjusted to a range of 1 to 50 nm, more preferably adjusted to a range of 1 to 20 nm. There is no particular limitation on the relationship between the film thicknesses of the blue, green and red light emitting layers.

  For the production of the light-emitting layer, a light-emitting material or a host compound, which will be described later, is formed by forming a film by a known thin film forming method such as a vacuum deposition method, a spin coating method, a casting method, an LB method, or an inkjet method. it can.

  Each light emitting layer may be a mixture of a plurality of light emitting materials, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer.

  As a structure of the light emitting layer, it is preferable to contain a host compound and a light emitting material (also referred to as a light emitting dopant compound) and emit light from the light emitting material.

<Host compound>
As the host compound contained in the light emitting layer of the organic EL device, a compound having a phosphorescence quantum yield of phosphorescence emission at room temperature (25 ° C.) of less than 0.1 is preferable. More preferably, the phosphorescence quantum yield is less than 0.01. Moreover, it is preferable that the volume ratio in the layer is 50% or more among the compounds contained in a light emitting layer.

  As the host compound, known host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the movement of charges, and the organic EL element can be made highly efficient. In addition, by using a plurality of kinds of light emitting materials described later, it is possible to mix different light emission, thereby obtaining an arbitrary light emission color.

  The host compound used may be a conventionally known low molecular compound, a high molecular compound having a repeating unit, or a low molecular compound having a polymerizable group such as a vinyl group or an epoxy group (evaporation polymerizable light emitting host). .

  As the known host compound, a compound having a hole transporting ability and an electron transporting ability, preventing an increase in emission wavelength, and having a high Tg (glass transition temperature) compound is preferable. The glass transition point (Tg) here is a value obtained by a method based on JIS-K-7121 using DSC (Differential Scanning Colorimetry).

  Specific examples of known host compounds include compounds described in the following documents. For example, Japanese Patent Application Laid-Open Nos. 2001-257076, 2002-308855, 2001-313179, 2002-319491, 2001-357777, 2002-334786, 2002-8860 Gazette, 2002-334787 gazette, 2002-15871 gazette, 2002-334788 gazette, 2002-43056 gazette, 2002-334789 gazette, 2002-75645 gazette, 2002-338579 gazette. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453. No. 2003-3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-286061, No. 2002-280183, No. 2002-299060. 2002-302516, 2002-305083, 2002-305084, 2002-308837, and the like.

<Light emitting material>
Next, the light emitting material will be described.

  In the present invention, a phosphorescent compound (also referred to as a phosphorescent compound or a phosphorescent material) is used as the light-emitting material.

  A phosphorescent compound is a compound in which light emission from an excited triplet is observed. Specifically, a phosphorescent compound emits phosphorescence at room temperature (25 ° C.), and a phosphorescence quantum yield of 0.01 at 25 ° C. Although defined as the above compounds, the preferred phosphorescence quantum yield is 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, when using a phosphorescent compound in the present invention, the above phosphorescence quantum yield (0.01 or more) is achieved in any solvent. It only has to be done.

  There are two types of light emission principle of the phosphorescent compound. 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 used for the phosphorescent compound. The phosphorescent compound is an energy transfer type in which light emission from the phosphorescent compound is obtained by transferring to the phosphorescent compound, and the other is that the phosphorescent compound becomes a carrier trap and carrier recombination occurs on the phosphorescent compound. In any case, the excited state energy of the phosphorescent compound is lower than the excited state energy of the host compound.

  The phosphorescent compound can be appropriately selected from known compounds used for the light-emitting layer of the organic EL device, and preferably a complex compound containing a group 8-10 metal in the periodic table of elements. More preferred are iridium compounds, osmium compounds, platinum compounds (platinum complex compounds), and rare earth complexes, and most preferred are iridium compounds.

  In the present invention, at least one light emitting layer may contain two or more phosphorescent compounds, and the concentration ratio of the phosphorescent compounds in the light emitting layer may vary in the thickness direction of the light emitting layer. Good.

  The phosphorescent compound is preferably 0.1% by volume or more and less than 30% by volume with respect to the total amount of the light emitting layer.

  The phosphorescent compound of the present invention is preferably a compound represented by the following general formula (4).

<< Compound Represented by Formula (4) >>
As the phosphorescent compound according to the organic EL device of the present invention, a compound represented by the general formula (4) is preferable.

  Hereinafter, the compound represented by Formula (4) will be described. The phosphorescent compound represented by the general formula (4) (also referred to as a phosphorescent metal complex) is preferably contained as a luminescent dopant in the light emitting layer of the organic EL device of the present invention. However, it may be contained in a constituent layer other than the light emitting layer (the constituent layer of the organic EL element of the present invention will be described in detail later).

  In the general formula (4), examples of the aromatic hydrocarbon ring that A1 forms with P—C include a benzene ring, a biphenyl ring, a naphthalene ring, an azulene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, a chrysene ring, a naphthacene ring, Triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, Examples include a pyrene ring, a pyrantolen ring, and anthraanthrene ring.

  These rings may further have a substituent represented by Y1 in the general formula (1).

  In the general formula (4), as the aromatic heterocycle formed by A1 together with PC, furan ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, Benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, azacarbazole A ring etc. are mentioned.

  Here, the azacarbazole ring refers to one in which one or more carbon atoms of the benzene ring constituting the carbazole ring are replaced with a nitrogen atom.

  These rings may further have a substituent represented by Y1 in the general formula (1). In the general formula (4), the aromatic heterocycle formed by A2 together with QN includes an oxazole ring, an oxadiazole ring, an oxatriazole ring, an isoxazole ring, a tetrazole ring, a thiadiazole ring, a thiatriazole ring, Examples include a thiazole ring, a pyrrole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, a pyrazole ring, and a triazole ring.

  These rings may further have a substituent represented by Y1 in the general formula (1).

  In the general formula (4), examples of the bidentate ligand represented by P1-L1-P2 include phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabole, acetylacetone, and picolinic acid. .

  In the general formula (4), j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, j1 + j2 represents 2 or 3, and j2 is preferably 0.

  In the general formula (4), M1 is a transition metal element of group 8 to group 10 (also simply referred to as a transition metal) in the periodic table, and is preferably iridium.

  The phosphorescent compound of the present invention is more preferably a compound represented by the following general formula (5).

<< Compound Represented by Formula (5) >>
Among the compounds represented by the general formula (4) according to the present invention, the compound represented by the general formula (5) is preferable.

  In the general formula (5), examples of the hydrocarbon ring group represented by Z include a non-aromatic hydrocarbon ring group and an aromatic hydrocarbon ring group, and examples of the non-aromatic hydrocarbon ring group include a cyclopropyl group. , Cyclopentyl group, cyclohexyl group and the like. These groups may be unsubstituted or have a substituent described later.

  Examples of the aromatic hydrocarbon ring group (also referred to as aromatic hydrocarbon group, aryl group, etc.) include, for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl. Group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group and the like.

  These groups may be unsubstituted or may have a substituent represented by Y1 in the general formula (1).

  In the general formula (5), examples of the heterocyclic group represented by Z include a non-aromatic heterocyclic group and an aromatic heterocyclic group. Examples of the non-aromatic heterocyclic group include an epoxy ring and an aziridine group. Ring, thiirane ring, oxetane ring, azetidine ring, thietane ring, tetrahydrofuran ring, dioxolane ring, pyrrolidine ring, pyrazolidine ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, thiazolidine ring, ε-caprolactone ring, ε- Caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, trioxane ring, tetrahydrothiopyran ring, thiomorpholine Ring, thiomorpholine-1,1-dioxide And groups derived from a ring, a pyranose ring, a diazabicyclo [2,2,2] -octane ring, and the like.

  These groups may be unsubstituted or may have a substituent represented by Y1 in the general formula (1).

  Examples of the aromatic heterocyclic group include pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, 1,2,4-triazol-1-yl). Group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group , Benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (indicating that one of the carbon atoms constituting the carboline ring of the carbolinyl group is replaced by a nitrogen atom), quinoxalinyl Group, pyridazinyl group, triazinyl group, key Zoriniru group, phthalazinyl group, and the like.

  These groups may be unsubstituted or may have a substituent represented by Y1 in the general formula (1).

  Preferably, the group represented by Z is an aromatic hydrocarbon ring group or an aromatic heterocyclic group.

  In the general formula (5), the aromatic hydrocarbon ring that A1 forms with P—C includes benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring , Triphenylene ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring , Pyrene ring, pyranthrene ring, anthraanthrene ring and the like.

  These rings may further have a substituent represented by Y1 in the general formula (1).

  In the general formula (5), the aromatic heterocycle formed by A1 together with P—C includes furan ring, thiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzo Imidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, And azacarbazole ring.

  Here, the azacarbazole ring refers to one in which one or more carbon atoms of the benzene ring constituting the carbazole ring are replaced with a nitrogen atom.

  These rings may further have a substituent represented by Y1 in the general formula (1).

  In -C (R01) = C (R02)-, -N = C (R02)-, and -C (R01) = N- represented by A3 in the general formula (5), each represented by R01 and R02 The substituent which is synonymous with the substituent represented by Y1 in General formula (1).

  In the general formula (5), examples of the bidentate ligand represented by P1-L1-P2 include phenylpyridine, phenylpyrazole, phenylimidazole, phenyltriazole, phenyltetrazole, pyrazabole, acetylacetone, and picolinic acid. .

  J1 represents an integer of 1 to 3, and j2 represents an integer of 0 to 2, j1 + j2 represents 2 or 3, and j2 is preferably 0.

  In General Formula (5), Group 8 to Group 10 transition metal elements in the periodic table of elements represented by M1 (also simply referred to as transition metals) in General Formula (4) are represented in the periodic table of elements represented by M1. It is synonymous with the transition metal element of Group 8-10.

  Specific examples of the phosphorescent compound according to the present invention are shown below, but the present invention is not limited thereto.

  The above phosphorescent compounds are described in, for example, Organic Letter, vol. 16, 2579-2581 (2001), Inorganic Chemistry, Vol. 30, No. 8, 1685-1687 (1991), J. Am. Am. Chem. Soc. , 123, 4304 (2001), Inorganic Chemistry, Vol. 40, No. 7, 1704-1711 (2001), Inorganic Chemistry, Vol. 41, No. 12, 3055-3066 (2002) , New Journal of Chemistry. 26, 1171 (2002), European Journal of Organic Chemistry, Vol. 4, pages 695-709 (2004), and further synthesized by applying methods such as references described in these documents. it can.

[Middle layer]
A case where a non-light emitting intermediate layer (also referred to as an undoped region or the like) is provided between the light emitting layers will be described.

  The non-light emitting intermediate layer is a layer provided between the light emitting layers in the case of having a plurality of light emitting layers. The film thickness of the non-light emitting intermediate layer is preferably in the range of 1 to 20 nm, and further in the range of 3 to 10 nm suppresses interaction such as energy transfer between adjacent light emitting layers, and the current of the device This is preferable because a large load is not applied to the voltage characteristics.

  The material used for the non-light emitting intermediate layer may be the same as or different from the host compound of the light emitting layer, but may be the same as the host material of at least one of the adjacent light emitting layers. preferable.

  The non-light-emitting intermediate layer may contain a non-light-emitting layer, a compound common to each light-emitting layer (for example, a host compound), and each common host material (where a common host material is used) In the case where the physicochemical characteristics such as phosphorescence emission energy and glass transition point are the same, or the molecular structure of the host compound is the same, etc.) The barrier is reduced, and the effect of easily maintaining the injection balance of holes and electrons even when the voltage (current) is changed can be obtained. Furthermore, by using a host material having the same physical characteristics or the same molecular structure as the host compound contained in each light-emitting layer in the undoped light-emitting layer, device fabrication, which is a major problem in conventional organic EL device fabrication, is achieved. Complexity can also be eliminated.

  Since the host material is responsible for carrier transportation, a material having carrier transportation ability is preferable. Carrier mobility is used as a physical property representing carrier transport ability, but the carrier mobility of an organic material generally depends on the electric field strength. Since a material having a high electric field strength dependency easily breaks the balance between injection and transport of holes and electrons, it is preferable to use a material having a low electric field strength dependency of mobility for the intermediate layer material and the host material.

  On the other hand, in order to optimally adjust the injection balance of holes and electrons, it is also preferable that the non-light emitting intermediate layer functions as a blocking layer described later, that is, a hole blocking layer and an electron blocking layer. Can be mentioned.

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

  In a broad sense, the hole blocking layer has a function of an electron transport layer and is composed of a hole blocking material having a function of transporting electrons and having a remarkably small ability to transport holes, while transporting electrons. By blocking holes, the recombination probability of electrons and holes can be improved. Moreover, the structure of the electron carrying layer mentioned later can be used as a hole-blocking layer concerning this invention as needed. The hole blocking layer is preferably provided adjacent to the light emitting layer.

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

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

  The hole transport material has any one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. For example, triazole derivatives, 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, Examples thereof include stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

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

  Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' Di (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 also two 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 in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.

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

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

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

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

  It is preferable to use such a high-p-type hole transport layer because a device with lower power consumption can be manufactured.

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

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

In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq ₃ ), 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 Metal complexes replaced with Cu, Ca, Sn, Ga, or Pb can also be used as electron transport materials. 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. Further, the distyrylpyrazine derivatives exemplified as the material of the light emitting layer can also be used as the electron transport material, and inorganic semiconductors such as n-type-Si and n-type-SiC can be used as well as the hole injection layer and the hole transport layer. It can be used as an electron transport material.

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

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

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

[Injection layer: electron injection layer, hole injection layer]
The injection layer is provided as necessary, and includes an electron injection layer and a hole injection layer. As described above, between the anode electrode (hereinafter also referred to as the anode) and the light emitting layer or the hole transport layer, and a cathode electrode (hereinafter also referred to as the cathode). ) And the light emitting layer or the electron transport 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) ) ", Chapter 2, Chapter 2," Electrode Materials "(pp. 123-166), which has a hole injection layer and an electron injection layer.

  The details of the hole injection layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069, and the like. As a specific example, a phthalocyanine layer represented by copper phthalocyanine And an oxide layer typified by vanadium oxide, an amorphous carbon layer, and a polymer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.

  The details of the electron injection layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specifically, metals represented by strontium, aluminum and the like. Examples thereof include an alkali metal halide layer typified by potassium fluoride, an alkaline earth metal compound layer typified by magnesium fluoride, and an oxide layer typified by molybdenum oxide. The electron injection layer according to the present invention preferably has a laminated structure of a metal layer and an alkali metal halide layer or a laminated structure of an oxide layer, a metal layer and an alkali metal halide layer, and the metal oxide may be doped with an alkali metal. good. As for the quantity of the alkali metal doped to a metal oxide, 1-10 mass% is preferable. The electron injection layer is preferably a very thin film, and the film thickness is preferably in the range of 1 nm to 10 μm although it depends on the material.

[Anode electrode]
As the anode electrode (counter electrode) to be paired with the cathode electrode, the above-mentioned materials constituting the transparent conductivity may be used, or metals, alloys, electrically conductive compounds and mixtures thereof as electrode materials Can also be 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. The counter electrode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. Further, the sheet resistance as the counter electrode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm.

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

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Production of double-sided emission type organic EL elements >>
The organic EL elements 1 to 29 were produced so that the light emission area was 5 cm × 5 cm.

  This will be described below with reference to the drawings. FIG. 1 is an example showing a configuration of an organic electroluminescence element having a cathode electrode laminated in four layers.

[Production of Organic EL Element 1]
(Formation of anode)
An ITO electrode 2 (anode) made of an ITO layer was formed on a transparent glass substrate 1 by depositing and patterning ITO using a sputtering method under a thickness of 100 nm. Next, the substrate provided with the ITO layer was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.

(Formation of hole injection layer to electron transport layer)
The substrate provided with the ITO layer is fixed to a substrate holder of a commercially available vacuum deposition apparatus, and α-NPD, H4, Ir-4, BAlq, Alq ₃ , and copper phthalocyanine are placed in a resistance heating board made of tantalum, respectively. The first vacuum chamber was attached.

  Furthermore, aluminum was put into a tungsten resistance heating board and attached to the second vacuum chamber of the vacuum deposition apparatus.

First, after reducing the pressure of the first vacuum chamber to 4 × 10 ⁻⁴ Pa, the heating board containing α-NPD was energized and heated, and the ITO layer was deposited at a deposition rate of 0.1 nm / second to 0.2 nm / second. A hole injection / hole transport layer 3 having a thickness of 20 nm was provided thereon.

  Further, the heating board containing H4 and the board containing Ir-4 are energized independently to adjust the deposition rate of H4 as a light emitting host and Ir-4 as a light emitting dopant to 100: 6. Then, the light emitting layer 4 having a thickness of 30 nm was provided.

  Next, the heating board containing BAlq was energized and heated to provide a hole blocking layer 5 having a film thickness of 10 nm at a deposition rate of 0.1 nm / second to 0.2 nm / second.

Further, the heating board containing Alq ₃ was heated by energization to provide an electron transport layer 6 having a film thickness of 20 nm at a deposition rate of 0.1 nm / second to 0.2 nm / second.

(Formation of electron injection layer)
Next, the heating board containing potassium fluoride is energized and heated to form a potassium fluoride layer having a film thickness of 1 nm at a deposition rate of 0.01 nm / second to 0.02 nm / second, and the electron injection layer 7 is formed. Provided.

(Formation of transparent conductive layer (cathode))
Next, the element formed up to the electron injection layer was transferred to a commercially available parallel plate sputtering apparatus equipped with an ITO target in advance, and after reducing the pressure in the chamber of the sputtering apparatus to 5 × 10 ⁻³ Pa, nitrogen gas and oxygen gas were added. While flowing, discharge was performed at a DC output of 500 W, and a transparent conductive layer (cathode) of an ITO conductive layer having a film thickness of 10 nm / second and a film thickness of 100 nm was formed.

(Element sealing)
Finally, the device obtained above is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (Lux Track LC0629B, manufactured by Toagosei Co., Ltd.) is used as a sealing material around it. This was applied, brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed, and a double-sided emission type organic EL device 1 was obtained.

[Production of Organic EL Element 2]
(Formation of anode to electron injection layer)
The film from the anode to the electron injection layer was formed by the same method as the organic EL element 1.

(Formation of sputter buffer layer)
Next, the heating board containing copper phthalocyanine was energized and heated to provide a sputtering buffer layer having a film thickness of 150 nm at a deposition rate of 1 nm / second to 2 nm / second.

(Formation of cathode)
A cathode was formed in the same manner as in the organic EL element 1.

(Element sealing)
The double-sided emission type organic EL device 2 was obtained by curing and sealing in the same manner as the organic EL device 1.

[Production of organic EL elements 3 to 4]
Organic EL elements 3 to 4 were produced in the same manner as the organic EL element 2 except that the material of the sputter buffer layer was changed from copper phthalocyanine to the materials described in Tables 1 and 2.

[Production of Organic EL Element 5]
(Formation of anode to electron injection layer)
The film from the anode to the electron injection layer was formed by the same method as that for the organic EL element 2.

(Formation of sputter buffer layer)
Next, the heating board containing lithium and the heating board containing Alq ₃ were energized independently to adjust the deposition rate of lithium and Alq ₃ to 1:10, and the film thickness was 150 nm. A sputter buffer layer was provided.

(Formation of cathode)
A cathode was formed in the same manner as the organic EL element 2.

(Element sealing)
The double-sided emission type organic EL element 5 was obtained by curing and sealing in the same manner as the organic EL element 2.

[Production of Organic EL Element 6]
(Formation of anode to electron injection layer)
The film from the anode to the electron injection layer was formed by the same method as the organic EL element 1.

(Formation of four-layered cathode electrode (cathode))
Next, the element formed up to the electron injection layer is transferred to the second vacuum chamber while being vacuumed, and after the second vacuum chamber is depressurized to 4 × 10 ⁻⁴ Pa, the heating board containing aluminum is energized, A metal layer 8 made of aluminum having a film thickness of 5 nm was formed at a deposition rate of 0.1 to 0.1 nm / second to 0.2 nm / second.

Next, after the element formed up to the metal layer made of aluminum was returned to the first vacuum chamber while being vacuumed, and the second vacuum chamber was depressurized to 4 × 10 ⁻⁴ Pa, a heating board containing cesium and Alq ₃ The heating board was energized independently to adjust the deposition rate of cesium and Alq ₃ to 1:25, and an Alq ₃ layer doped with cesium having a thickness of 78 nm was provided.

  Furthermore, the heating board containing titanium dioxide was energized and heated to provide a layer 10 having a metal oxide semiconductor made of titanium dioxide having a film thickness of 2 nm at a deposition rate of 0.1 nm / second to 0.2 nm / second.

Finally, the element formed up to the titanium dioxide layer (the layer having the metal oxide semiconductor) was transferred to a commercially available parallel plate sputtering apparatus in which an ITO target was previously mounted in a vacuum state, and the inside of the sputtering apparatus chamber was 5 × 10 ⁻ After depressurizing to ³ Pa, discharging was performed at a DC output of 500 W while flowing nitrogen gas and oxygen gas, and a transparent conductive layer 11 made of ITO having a film thickness of 10 nm / second was provided, and four comparative layers were laminated. A cathode electrode (cathode) was formed.

(Element sealing)
Finally, the device obtained above is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (Lux Track LC0629B, manufactured by Toagosei Co., Ltd.) is used as a sealing material around it. This was applied, brought into close contact with the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed, and a double-sided emission type organic EL element 6 was obtained.

[Production of Organic EL Element 7]
A layer doped with an element belonging to Group 1 or Group 2 of the periodic table by changing the material doped into the Alq ₃ layer constituting the cathode electrode laminated in 4 layers from the comparative cesium to sodium according to the present invention A double-sided emission type organic EL device 7 of the present invention equipped with the cathode electrode 12 according to the present invention was obtained in the same manner as the organic EL device 6 except that No. 9 was produced.

[Production of Organic EL Element 8]
Double-sided emission type organic EL in the same manner as the organic EL element 7 except that the material of the titanium dioxide layer which is a layer having a metal oxide semiconductor constituting the four-layered cathode electrode is changed from titanium dioxide to molybdenum trioxide. Element 8 was obtained.

[Production of Organic EL Element 9]
Organic EL element 8 except that the Alq ₃ layer (layer doped with elements belonging to Group 1 or Group 2 of the periodic table) constituting the cathode electrode laminated in four layers is changed from sodium to potassium. A double-sided emission type organic EL device 9 was obtained in the same manner as above.

[Production of organic EL elements 10 to 16]
A method similar to that of the organic EL element 9 except that the film thickness of the molybdenum oxide layer constituting the four-layered cathode electrode and the Alq ₃ layer doped with potassium is changed to the film thickness shown in Table 2. EL elements 10 to 16 were produced.

[Preparation of organic EL elements 17 to 19]
The same as the organic EL element 15 except that the material of the Alq ₃ layer constituting the four-layered cathode electrode is changed from the Alq ₃ to the exemplified compound represented by the general formula (1) described in Table 1 and Table 2. Organic EL elements 17 to 19 were produced by the method.

[Production of organic EL elements 20 to 22]
Organic EL elements 20 to 22 were produced in the same manner as the organic EL element 19 except that the material contained in the light emitting layer was changed from Ir-4 to the phosphorescent compounds described in Tables 1 and 2.

[Preparation of organic EL elements 23 to 24]
The organic EL element 19 was prepared in the same manner as the organic EL element 19 except that the material doped in the layer composed of the compound (10) constituting the four-layered cathode electrode was changed from potassium to the materials shown in Tables 1 and 2. Elements 23 to 24 were produced.

[Production of Organic EL Elements 25-26]
Organic EL element except that the material of the molybdenum trioxide layer (layer having a metal oxide semiconductor) constituting the four-layered cathode electrode is changed from molybdenum oxide to rhenium dioxide and nickel oxide described in Tables 1 and 2 Organic EL elements 25 to 26 were produced in the same manner as in No. 22.

[Production of Organic EL Element 27]
(Formation of anode to cathode)
The film from the anode to the cathode was formed by the same method as the organic EL element 22.

(Preparation of auxiliary electrode)
On the cathode, an auxiliary electrode made of a line-shaped silver pattern was produced at a spacing of a line width of 50 μm, a thickness of 1 μm, and a pitch of 1,000 μm using a shadow mask.

(Element sealing)
The double-sided emission type organic EL element 27 was obtained by curing and sealing in the same manner as the organic EL element 22.

[Production of organic EL elements 28 to 29]
The same as the organic EL element 27 except that the material of the molybdenum trioxide layer (layer having a metal oxide semiconductor) constituting the four-layered cathode electrode is changed from molybdenum trioxide to the materials shown in Tables 1 and 2. The organic EL elements 28 to 29 were produced by a simple method.

[Production of organic EL elements 30 to 33]
Tables 1 and 2 show the film thicknesses of four layers of layers having a metal oxide semiconductor constituting the cathode electrode and layers doped with elements belonging to Group 1 or Group 2 of the periodic table) Organic EL elements 30 to 33 were produced in the same manner as the organic EL element 19 except that the organic EL elements were changed to.

  In addition, the detail of the compound used for preparation of the said organic EL element is as follows.

<< Evaluation of organic EL elements >>
About each produced said organic EL element, the voltage was measured in accordance with the following method.

[Measurement of drive voltage]
With respect to each organic EL element produced as described above, the voltage when the sum of the front luminances on both the anode side and the cathode side was 1000 cd / m ² was defined as the voltage of each element. A spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used for the measurement of luminance. The smaller the numerical value of the voltage obtained, the better the result.

[Measurement of luminous efficiency]
For each of the organic EL devices produced above, the external extraction quantum efficiency (%) when a ^2.5 mA / cm ² constant current was passed was measured. For the measurement, a spectral radiance meter CS-1000 (manufactured by Konica Minolta Sensing) was used. At this time, the external extraction quantum efficiency was calculated from the total luminance measured from both sides of the organic EL element.

  Based on the measurement result of the external extraction quantum efficiency (%) obtained, a relative value when the external extraction quantum efficiency (%) of the comparative organic EL element 1 was set to 1 was obtained, and this was used as a measure of luminous efficiency. . The larger the relative value of the external quantum efficiency, the higher the light emission efficiency, which represents a preferable result.

  Tables 1 and 2 show the results obtained as described above.

  In Tables 1 and 2, a layer having a metal oxide semiconductor is a metal oxide semiconductor layer, a layer doped with an element belonging to Group 1 or Group 2 of the periodic table is doped, and aluminum is aluminum. Abbreviated.

  As is clear from the results shown in Tables 1 and 2, it can be seen that the organic EL device according to the present invention has superior luminous efficiency and low driving voltage compared to the comparative example.

Example 2
<< Manufacturing of lighting device >>
An illumination device including the organic EL element of the present invention was created.

  About each of the organic EL elements 5 to 33 of the present invention, the cured / sealed surface is covered with a glass case, a 300 μm-thick glass substrate is used as a sealing substrate, and an epoxy photo-curing type is used as a sealing material around. Adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.) was applied, and this was overlaid on the cathode and adhered to the transparent substrate, irradiated with UV light from the glass substrate side, cured and sealed, FIG. A lighting device as shown in FIG. 3 was formed.

  FIG. 2 is a schematic perspective view showing an example of a lighting device using the organic EL element of the present invention. The organic EL element 101 of the present invention is covered with a glass cover 102 (in addition, the sealing operation with the glass cover is a glove box (purity 99.999 in a nitrogen atmosphere without bringing the organic EL element 101 into contact with the atmosphere). % In a high purity nitrogen gas atmosphere).

  FIG. 3 is a schematic cross-sectional view showing an example of a lighting device using the organic EL element of the present invention. In FIG. 3, 105 denotes a cathode, 106 denotes an organic EL layer, and 107 denotes a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and a water catching agent 109 is provided. The emitted light 110 is irradiated downward in the figure.

  When a flat lamp as shown in FIGS. 2 and 3 was produced and the flat lamp was energized, illumination light was obtained for each of the organic EL elements 5 to 33, and it was found that the flat lamp could be used as a lighting device.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode electrode 3 Hole injection / hole transport layer 4 Light emitting layer 5 Hole blocking layer 6 Electron transport layer 7 Electron injection layer 8 Metal layer 9 Elements doped with Group 1 or Group 2 of the periodic table are doped Layer 10 Layer having metal oxide semiconductor 11 Transparent conductive layer 12 Cathode electrode 101 Organic EL element 102 Glass cover 105 Cathode 106 Organic EL layer 107 Glass substrate with transparent electrode 108 Nitrogen gas 109 Water catching agent 110 Light emitted

Claims (16)

In an organic electroluminescence element in which an anode electrode, a light emitting layer, and a cathode electrode are laminated in this order on one main surface of a substrate, the cathode electrode is formed by disposing a transparent conductive layer and a metal oxide semiconductor from a side far from the light emitting layer. And a layer doped with an element belonging to Group 1 or Group 2 of the periodic table and a metal layer are laminated in this order. The element belonging to the group has a standard electrode potential of -3.00 V vs. metal ion (M ^{n +} ) / metal (M) system. An organic electroluminescence device characterized in that it is a metal or a metal compound of a noble element than SHE, and the light emitting layer contains a phosphorescent compound. The organic electroluminescence element according to claim 1, wherein the transparent conductive layer is a layer formed by a sputtering method. The organic electroluminescence device according to claim 1, wherein the layer including the metal oxide semiconductor has an oxygen-deficient non-stoichiometric composition. The organic electroluminescence device according to any one of claims 1 to 3, wherein the metal oxide semiconductor is molybdenum oxide, rhenium oxide, or nickel oxide. The organic electroluminescent element according to any one of claims 1 to 4, wherein the element belonging to Group 1 or Group 2 of the periodic table is potassium. The sum of the film thicknesses of the layer having the metal oxide semiconductor and the layer doped with an element belonging to Group 1 or Group 2 of the periodic table is 100 nm or more and 200 nm or less. 6. The organic electroluminescence device according to any one of 5 above. The ratio between the thickness of the layer having the metal oxide semiconductor and the thickness of the layer doped with an element belonging to Group 1 or Group 2 of the periodic table is in the range of 1:10 to 1:20. the organic electroluminescent device according to any one of claims 1 to 6, wherein. Claim 1-7 in which the main component of the layer element belonging to Group 1 or Group 2 the periodic table is doped and having a compound represented by the following general formula (1) 1 The organic electroluminescent element of the item.
General formula (1)
(Ar1) n1-Y1
[Wherein, n1 represents an integer of 1 or more, Y1 represents a substituent when n1 is 1, and represents a mere bond or an n1-valent linking group when n1 is 2 or more. Ar1 represents a group represented by the following general formula (A). When n1 is 2 or more, a plurality of Ar1s may be the same or different. However, the compound represented by the general formula (1) has at least two condensed aromatic heterocycles in which three or more rings are condensed in the molecule. ]

[Wherein, X represents -N (R)-, -O-, -S- or -Si (R) (R ')-, and E1-E8 represents -C (R1) = or -N = R, R ′ and R1 represent a hydrogen atom, a substituent or a linking site with Y1. * Represents a linking site with Y1. Y2 represents a simple bond or a divalent linking group. Y3 and Y4 each represent a group derived from a 5-membered or 6-membered aromatic ring, and at least one represents a group derived from an aromatic heterocycle containing a nitrogen atom as a ring constituent atom. n2 represents an integer of 1 to 4. ] The organic electroluminescent device according to claim 8 , wherein the compound represented by the general formula (1) is a compound represented by the following general formula (2).

[Wherein Y5 represents a divalent linking group comprising an arylene group, a heteroarylene group, or a combination thereof. E51 to E66 each represent -C (R3) = or -N =, and R3 represents a hydrogen atom or a substituent. Y6 to Y9 each represents a group derived from an aromatic hydrocarbon ring or a group derived from an aromatic heterocycle, and at least one of Y6 or Y7 and at least one of Y8 or Y9 is an aromatic group containing an N atom. Represents a group derived from a group heterocycle. n3 and n4 represent an integer of 0 to 4, but n3 + n4 is an integer of 2 or more. ] The organic electroluminescent device according to claim 8 , wherein the compound represented by the general formula (1) is a compound represented by the following general formula (3).

[Wherein Y5 represents a divalent linking group comprising an arylene group, a heteroarylene group, or a combination thereof. E51 to E66 and E71 to E88 each represent -C (R3) = or -N =, and R3 represents a hydrogen atom or a substituent. However, at least one of E71 to E79 and at least one of E80 to E88 represents -N =. n3 and n4 represent an integer of 0 to 4, but n3 + n4 is an integer of 2 or more. ] The organic electroluminescent device according to any one of claims 1 to 10, wherein the phosphorescent compound is a compound represented by the following general formula (4).

[Wherein, P and Q each represent a carbon atom or a nitrogen atom, and A1 represents an atomic group which forms an aromatic hydrocarbon ring or an aromatic heterocycle together with PC. A2 represents an atomic group which forms an aromatic heterocycle with QN. P1-L1-P2 represents a bidentate ligand, and P1 and P2 each independently represent a carbon atom, a nitrogen atom, or an oxygen atom. L1 represents an atomic group that forms a bidentate ligand together with P1 and P2. j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, and j1 + j2 is 2 or 3. M1 represents a group 8-10 transition metal element in the periodic table. ] The organic electroluminescent device according to claim 11 , wherein the compound represented by the general formula (4) is a compound represented by the following general formula (5).

[Wherein Z represents a hydrocarbon ring group or a heterocyclic group. P and Q each represent a carbon atom or a nitrogen atom, and A1 represents an atomic group that forms an aromatic hydrocarbon ring or an aromatic heterocyclic ring together with PC. A3 represents -C (R01) = C (R02)-, -N = C (R02)-, -C (R01) = N- or -N = N-, and each of R01 and R02 represents a hydrogen atom or a substituent. Represents a group. P1-L1-P2 represents a bidentate ligand, and P1 and P2 each independently represent a carbon atom, a nitrogen atom, or an oxygen atom. L1 represents an atomic group that forms a bidentate ligand together with P1 and P2. j1 represents an integer of 1 to 3, j2 represents an integer of 0 to 2, and j1 + j2 is 2 or 3. M1 represents a group 8-10 transition metal element in the periodic table. ] The organic electroluminescent device according to claim 11 or 1 2, characterized in that said M1 represents iridium. The organic electroluminescent device according to any one of claims 1 to 1 3, characterized in that it comprises an auxiliary electrode on the transparent conductive layer. The organic electroluminescent device according to any one of claims 1 to 1 4, wherein the organic electroluminescent device is a double-sided emission type. An illuminating device comprising the organic electroluminescent element according to any one of claims 1 to 15 .

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