JP2015228409A - Organic light-emitting element having cobalt monovalent complex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic light-emitting element having high stability against oxygen.SOLUTION: The organic light-emitting element includes an anode 21, a cathode 23, and a light-emitting layer disposed between the anode and the cathode and further includes an organic compound layer 22 disposed between the cathode and the light-emitting layer. The organic compound layer has a cobalt monovalent complex represented by general formula [1].

Description

  The present invention relates to an organic light emitting element, a display device, an image information processing device, an illumination device, an image forming device, and an exposure device.

  An organic light emitting device is an electronic device having an anode, a cathode, and a light emitting layer having an organic compound disposed between both electrodes. Each carrier (hole, electron) injected from each electrode (anode, cathode) recombines in the light emitting layer to generate excitons, and the organic light emitting element emits light when the excitons return to the ground state. Release.

  In the organic light emitting device, an electron injection layer is provided in addition to the light emitting layer for the purpose of good electron injection from the cathode. The electron injection layer is a layer for facilitating injection of electrons from the cathode, and often has an electron transporting material that is an organic compound and an n-type dopant having a high electron donor property. Doping an n-type dopant having a shallow donor level increases the apparent Fermi level of the electron injection layer and reduces the difference between the work function of the cathode and the electron injection energy barrier. As a result, the organic light emitting device can emit light with high luminance at a low applied voltage.

  However, the organic light emitting device has room for further improvement in terms of driving voltage and durability. Regarding the electron injection layer, it is required to further improve the electron injection property itself and to improve the stability against moisture, oxygen and the like.

  As one of the n-type dopants used for the electron injection layer, cobaltcene, which is a cobalt divalent complex represented by the following formula, is known. Patent Document 1 discloses an organic material in which electrons are injected from an organic layer made of PEDOT: PSS into a charge injection layer using a charge transporting organic material (host) and cobaltcene (n-type dopant) represented by the following structure A. An electronic device is described. Patent Document 2 also describes that the following cobaltcene may be used as a charge injection / transport layer of an organic electronic device as one of metal cyclopentadiene compounds.

Structure A

US Pat. No. 7,981,328 Specification Japanese Patent Registration No. 4554329

Ernst Oto Fischer, Gerhard Edwin Herberich, “Uber Aromaton Komplexex von Metallen, XLIV. Uber die Reaktivate des Di-Citentade III-KiB” D. Vasudevan, H.M. Wendt, “Electroduction of oxygen in aprotic media” Journal of Electroanalytical Chemistry (1995), Vol. 392, 69-74

  Cobaltene described in Patent Document 1 is a radical having an unpaired electron, and since it is a 19-electron complex, the stability of the complex is low. Furthermore, since it has a low first oxidation potential, it is easily oxidized by oxygen in the air. In addition, when used in an organic electronic device, the volatility is too high, and it is difficult to perform vacuum heating deposition with good control.

  An object of the present invention is to provide an organic light-emitting device having an electron injection layer that has high stability to oxygen and can be formed by a vacuum heating deposition method.

Therefore, the present invention relates to an anode, a cathode, a light emitting layer disposed between the anode and the cathode, and an organic compound disposed between the cathode and the light emitting layer and in contact with the cathode. Further comprising a layer,
Provided is an organic light-emitting device, wherein the organic compound layer has a cobalt monovalent complex represented by the following general formula [1].

In the formula [1], X _{1 to} X ₉ each represent a hydrogen atom or a methyl group. Ar represents a substituted or unsubstituted aromatic hydrocarbon group.

  ADVANTAGE OF THE INVENTION According to this invention, the organic light emitting element which has high stability with respect to oxygen and has an electron injection layer which can be formed by a vacuum heating vapor deposition method can be provided.

It is a schematic diagram showing the structure of exemplary compound C101 concerning this embodiment. It is a cross-sectional schematic diagram which shows an example of the display apparatus which has the organic light emitting element which concerns on this invention, and the active element connected to this organic light emitting element. It is a schematic diagram which shows an example of the image type apparatus which concerns on this embodiment. It is a schematic diagram which shows an example of the exposure apparatus which concerns on this embodiment. It is a schematic diagram which shows an example of the illuminating device which concerns on this embodiment.

  The organic light emitting device of the present invention further comprises an anode, a cathode, a light emitting layer disposed between the anode and the cathode, and an organic compound layer disposed between the cathode and the light emitting layer. The organic compound layer has a cobalt complex represented by the general formula [1].

  And the cathode which the organic light emitting element of this invention has is a metal.

  The organic light emitting device of the present invention has a cobalt monovalent complex represented by the general formula [1] in an organic compound layer disposed between the light emitting layer and the cathode.

  The organic compound layer disposed between the light emitting layer and the cathode is called an electron transport layer, an electron injection layer, or the like. In particular, the organic compound layer in contact with the cathode is also called an electron injection layer. The organic light emitting device of the present invention preferably has a cobalt monovalent complex represented by the general formula [1] in an organic compound layer disposed between the light emitting layer and the cathode and in contact with the cathode, that is, an electron injection layer.

In the organic light emitting device, the compound constituting the electron injection layer is preferably highly stable against oxygen. Therefore, the electron injection layer is a monovalent cobalt monovalent ligand having a cyclopentadiene-based ligand which is a zero-valent ligand of η ⁴ and has an aromatic hydrocarbon group as a substituent. It is preferable to have a complex.

  Furthermore, such a cobalt monovalent complex is preferable because it has an aromatic hydrocarbon group as a substituent and thus has an increased molecular weight, and therefore has low volatility to such an extent that vacuum heating deposition is possible.

(1) Cobalt monovalent complex The cobalt monovalent complex according to the present embodiment is a cobalt monovalent complex represented by the following general formula [1].

In the formula [1], X _{1 to} X ₉ each represent a hydrogen atom or a methyl group. Further, in the cobalt monovalent complex of the general formula [1], preferably, the cobalt monovalent complex in which X _{1 to} X ₉ are all hydrogen atoms.

  In the cobalt monovalent complex of the general formula [1], it is preferable that Ar is a phenyl group, a biphenyl-4-yl group, a naphthalen-2-yl group, or a 9,9-dimethylfluoren-2-yl group. Is a valence complex.

  In the formula [1], Ar represents a substituted or unsubstituted aromatic hydrocarbon group.

  Specific examples of the aromatic hydrocarbon group represented by Ar include a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenanthrenyl group, an anthracenyl group, a fluorenyl group, an acenaphthenyl group, a chrycenyl group, a pyrenyl group, a triphenylenyl group, Examples include, but are not limited to, a picenyl group, a fluoranthenyl group, a perylenyl group, a naphthacenyl group, and a 9,9-spirobifluorenyl group. Among these aromatic hydrocarbon groups, a phenyl group, a biphenyl group, a naphthyl group, or a fluorenyl group is preferable.

  The aromatic hydrocarbon group represented by Ar may further have a substituent. Specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, i-pentyl group , Tert-pentyl group, neopentyl group, n-hexyl group and other alkyl groups, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, norbornyl group, adamantyl group and other cycloalkyl groups, fluorine, chlorine, bromine and iodine Selected halogen atom, methoxy group, ethoxy group, i-propoxy group, n-butoxy group, alkoxy group such as tert-butoxy group, N-methylamino group, N-ethylamino group, N, N-dimethylamino group, N, N-diethylamino group, N-methyl-N-ethylamino group, N-benzylamino group, N-methyl-N-base Dilamino group, N, N-dibenzylamino group, anilino group, N, N-diphenylamino group, N, N-dinaphthylamino group, N, N-difluorenylamino group, N-phenyl-N-tolylamino group N, N-ditolylamino group, N-methyl-N-phenylamino group, N, N-dianisolylamino group, N-mesityl-N-phenylamino group, N, N-dimesitylamino group, N-phenyl-N Substituted amino groups such as-(4-tert-butylphenyl) amino group and N-phenyl-N- (4-trifluoromethylphenyl) amino group, phenyl group, naphthyl group, phenanthryl group, anthryl group, fluorenyl group, biphenylenyl Group, acenaphthylenyl group, chrysenyl group, pyrenyl group, triphenylenyl group, picenyl group, fluoranthenyl group, peryleneni Group, aromatic hydrocarbon group such as naphthacenyl group, biphenyl group, terphenyl group, thienyl group, pyrrolyl group, pyrazinyl group, pyridyl group, indolyl group, quinolyl group, isoquinolyl group, naphthyridinyl group, acridinyl group, phenanthrolinyl Carbazolyl group, benzo [a] carbazolyl group, benzo [b] carbazolyl group, benzo [c] carbazolyl group, phenazinyl group, phenoxazinyl group, phenothiazinyl group, benzothiophenyl group, dibenzothiophenyl group, benzofuranyl group, dibenzo Heteroaryl groups such as furanyl group, oxazolyl group, oxadiazolyl group, cyano group, trifluoromethyl group and the like can be mentioned. Of these substituents, a methyl group, a tert-butyl group, a methoxy group, a phenyl group, a naphthyl group, a fluorenyl group, a biphenyl group, and a cyano group are preferable. The alkyl group and cycloalkyl group may have a halogen atom. When the alkyl group has a halogen atom, a trifluoromethyl group is preferred.

  Among the substituents that the aromatic hydrocarbon group has, a methyl group or a tert-butyl group is preferable.

  In the cobalt monovalent complex of the general formula [1], Ar is preferably a cobalt monovalent complex selected from the group of aromatic hydrocarbon groups represented by the following formula [2].

In the formula [2], R _{1 to} R ₃₉ each represent a hydrogen atom, a halogen atom, an alkyl group which may have a halogen atom, or a cyano group.

The alkyl group represented by R _{1 to} R ₃₉ is preferably an alkyl group having 1 to 6 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, and tert-butyl. Group, n-pentyl group, i-pentyl group, tert-pentyl group, neopentyl group, n-hexyl group and the like. Among these alkyl groups, a methyl group or a tert-butyl group is particularly preferable. Further, the alkyl group represented by R _{1 to} R ₃₉ may have a halogen atom as a substituent, and in that case, a trifluoromethyl group is preferable.

  In the formula [2], * represents a bond with the cyclopentadiene ring in the general formula [1].

The cobalt monovalent complex according to this embodiment includes a −1 valent η ⁵ cyclopentadienyl ligand, a 0 valent η ⁴ 1-aryl-2,4-cyclopentadiene ligand, and a +1 valence. A half metallocene comprising a cobalt center metal. Here, metallocene is an organometallic compound having two cyclopentadienyl anions as η ⁵ -ligand, whereas half metallocene is one cyclopentadienyl anion represented by η ⁵ -ligand. It means an organometallic compound possessed as As an example of the cobalt monovalent complex according to this embodiment, an exemplary compound C101 will be described as shown in FIG.

  By the way, there are 18 electron rules for organometallic compounds. This is an empirical rule that in a complex of a d block element, a complex in which the sum of the number of d electrons possessed by the metal itself and the number of electrons donated from the ligand is 18 has high stability.

In the cobalt monovalent complex according to the present embodiment, η ⁵ -cyclopentadienyl ligand (number of donated electrons: 6) and η ⁴ -1-aryl-2,4-cyclopentadiene ligand (number of donated electrons). : 4) and an 18-electron complex of cobalt center metal (d electron number: 8). Therefore, it is a stable complex according to the 18-electron rule, and can actually be handled without causing significant decomposition or the like due to oxygen or moisture in the atmosphere.

Furthermore, it is clear from the cyclic voltammetry (CV) measurement that the cobalt monovalent complex according to the present embodiment has a sufficient and sufficient electron donor property as a donor compound for the electron injection layer. Specifically, the first oxidation potential obtained from the CV measurement of the exemplary compound C101 is −0.73 V (vs. Fc / Fc ⁺ ), which is low enough to function as an n-type dopant. I know that.

On the other hand, cobaltene is a 19-electron complex of two η ⁵ -cyclopentadienyl ligands (number of donor electrons: 6) and a cobalt center metal (number of d electrons: 7). Therefore, since it is in an electron-excess state with respect to 18 electrons, it is an unstable complex with high electron donor properties. Further, since cobaltene is a radical having an unpaired electron, it is also an unstable metallocene with high reaction activity. Therefore, cobaltcene is difficult to handle in the atmosphere and requires strict handling in an inert gas atmosphere.

  Cobaltene has a high electron donor property and is useful as an n-type dopant. However, when it is used for an organic electronic device, it has a problem that it is too volatile. Here, being too volatile means that the saturated vapor pressure at room temperature is sufficiently high, so that it is difficult to manufacture a device with good control by a heating vapor deposition method in a normal vacuum chamber.

  In Patent Document 1 or the like, cobalt cene is volatilized from an ampoule in an unheated room temperature in a vacuum chamber, and cobalt cene is doped into the organic film by the background vapor pressure of the generated cobalt cene. However, in such a device manufacturing method, it is difficult to obtain a dope film whose dope concentration or the like is highly controlled or to form a film continuously. Furthermore, not only is it difficult to keep the dope concentration constant due to the radiant heat generated by heat evaporation of other materials, but there is also a concern that the film already deposited may volatilize out of the film again.

  The reason why the volatility of cobaltcene is too high is that the molecular weight of cobaltcene is 189, which is very small.

  On the other hand, the cobalt monovalent complex according to the present embodiment is desirably used for an organic light emitting device by vacuum heating deposition. Therefore, if the volatility is too high like the above cobaltcene, it is not preferable because it volatilizes (sublimates) even at room temperature in a vacuum chamber, making it difficult to produce an organic light emitting device.

Therefore, the cobalt monovalent complex according to this embodiment has an η ⁴ -cyclopentadiene ligand provided with an aromatic hydrocarbon group, and thus has a molecular weight of at least 260, so that vacuum heating deposition can be controlled. be able to.

  On the other hand, the cobalt monovalent complex according to this embodiment is also required not to be thermally decomposed by high-temperature heating when performing sublimation purification or vacuum heating deposition. Therefore, the cobalt monovalent complex according to this embodiment needs to have moderately high volatility (sublimation) that does not cause thermal decomposition due to overheating. Therefore, the molecular weight of the cobalt monovalent complex according to this embodiment is preferably 500 or less.

  That is, the cobalt monovalent complex according to the present embodiment preferably has an appropriate range of volatility so that vacuum heating deposition can be controlled without causing thermal decomposition. It is preferably in the range of 260 to 500.

  In particular, in the cobalt monovalent complex in which Ar in the general formula [1] is selected from the aromatic hydrocarbon group group represented by the general formula [2], the size of the aromatic hydrocarbon group is appropriate. The molecular weight is preferably within the above range.

(2) Specific example of cobalt monovalent complex Below, the specific example of the cobalt monovalent complex concerning this Embodiment is shown.

Of the exemplified compounds, cobalt monovalent complex of first group shown in C101 to C137 is, _{X 1} to _{X 9} are all hydrogen atoms. These cobalt monovalent complexes of the first group are highly oxygen-stable and have a moderate electron donor property.

Of the exemplified compounds, cobalt monovalent complex of a second group shown in C201 to C215 is at least one or more methyl groups of _{X 1} to _{X 9.} In these second group of cobalt monovalent complexes, the electron donating property of the ligand is increased by the electron donation by the methyl group, the first oxidation potential is lower, and the electron donor property is higher.

(3) Layer structure of organic light emitting element The layer structure of the organic light emitting element of the present invention is a multilayer structure in which electrodes and various organic compound layers shown in the following (1) to (5) are sequentially laminated on a substrate. is there.

Each configuration has a light emitting layer and an electron injection layer, and the electron injection layer is adjacent to the cathode on the light emitting layer side. In the organic light emitting device of this embodiment, the cathode is made of metal.
(1) Anode / light emitting layer / electron injection layer / cathode (2) Anode / hole transport layer / light emitting layer / electron injection layer / cathode (3) Anode / hole transport layer / light emitting layer / electron transport layer / electron injection Layer / cathode (4) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (5) anode / hole transport layer / electron blocking layer / light emitting layer / hole blocking Layer / electron transport layer / electron injection layer / cathode However, these configuration examples are merely examples, and the configuration of the organic light-emitting device according to the present invention is not limited thereto.

  For example, an insulating layer, an adhesive layer or an interference layer is provided at the interface between the electrode and any organic compound layer, the electron transport layer or the hole transport layer is composed of two layers having different ionization potentials, It is possible to adopt a layer structure in which the light emitting material is composed of two layers different from each other.

  In the element configuration shown in the above (1) to (5), the configuration (5) is preferable because it has both an electron blocking layer and a hole blocking layer. That is, in (5) having the electron blocking layer and the hole blocking layer, both the hole and electron carriers can be more reliably confined in the light emitting layer, so that an organic light emitting device with high emission efficiency without carrier leakage is obtained. .

(4) Electron injection layer The electron injection layer which the organic light emitting element concerning this invention has has a cobalt monovalent complex shown by the said General formula [1]. The electron injection layer may be composed of only the cobalt monovalent complex, but preferably has a different type of compound from the cobalt monovalent complex.

  In that case, the cobalt monovalent complex is preferably used as an n-type dopant, and the cobalt monovalent complex and another type of compound are preferably used as an electron injection layer host.

  When the electron injection layer has an electron injection layer host, the concentration of the n-type dopant is 0.1 wt% or more and 80 wt% or less, preferably 1 wt% or more and 50 wt% based on the whole electron injection layer. Or less, more preferably 5 wt% or more and 30 wt% or less. That is, the weight ratio of the different kinds of compounds is preferably 20% by weight or more and 99.9% by weight or less.

  The electron injection layer having a cobalt monovalent complex in the present invention is in contact with the cathode. The cathode may be composed of a plurality of layers.

  Here, the n-type dopant is a material having a shallow HOMO level (low ionization potential) or a shallow SOMO level, and can form an electron donor level in the electron injection layer. Here, a shallow HOMO level or a shallow SOMO level is almost synonymous with a low first oxidation potential obtained in cyclic voltammetry (CV) measurement. In addition, the shallow HOMO level or the shallow SOMO level indicates that the HOMO level is closer to the vacuum level.

  On the other hand, the electron injection layer host is a material whose LUMO level functions as an electron conduction level and transports electrons donated from the n-type dopant in the electron injection layer.

When the electron injection layer has such an n-type dopant, the Fermi level of the electron injection layer having the n-type dopant, that is, the mixed material type electron injection layer, is shallower than the Fermi level of the electron injection layer host alone. . There is no Fermi level in a single organic compound, but here, the Fermi level is apparently the middle of the HOMO level and LUMO level.
As a result, the level difference between the LUMO level of the electron injection layer host, which is the electron conduction level, and the Fermi level of the electron injection layer is reduced, so that the energy barrier of electrons injected from the cathode to the electron conduction level is reduced. It is reduced.

(5) Electron Injection Layer Host The electron injection layer host may be a compound having any structure as long as the LUMO level is −4.5 eV or more and −2.8 eV or less.

  More specifically, as an electron injection layer host, an oxadiazole derivative, an oxazole derivative, a pyrazine derivative, a triazole derivative, a triazine derivative, a quinoline derivative, a quinoxaline derivative, a phenanthroline derivative, an organoaluminum complex, a condensed ring compound (for example, a fluorene derivative, Naphthalene derivatives, chrysene derivatives, anthracene derivatives, etc.) and anthraquinone derivatives. Specific examples of the electron injection layer host are shown below, but are not limited to these.

  The electron injection layer host described here may have, for example, an organic compound layer disposed between the electron injection layer and the light emitting layer, such as an electron transport layer and a hole blocking layer.

  The electron injection layer may have a reducing dopant in addition to the cobalt monovalent complex according to the present embodiment. The electron injection layer may have an n-type dopant different from the cobalt monovalent complex according to the present embodiment. For example, alkali metal, alkaline earth metal, rare earth metal, alkali metal oxide, alkali metal halogen , Alkali metal carbonates, alkali metal complexes, alkaline earth metal oxides, alkaline earth metal halides, alkali metal earth complexes, rare earth metal oxides, rare earth metal halides, rare earth metal complexes, etc. Is mentioned.

(About cathode)
The material constituting the cathode is preferably a metal having a small work function. Specifically, the work function is 2.0 eV or more and 5.0 eV or less. In addition, a metal oxide is also contained in the metal here.

  Examples of the cathode material include alkali metals such as lithium, alkaline earth metals such as calcium, and materials having a single metal or a plurality of types such as aluminum, titanium, manganese, silver, lead, and chromium. Alternatively, an alloy having at least one of these metals can also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, etc. can be used. Furthermore, it is possible to use a metal oxide such as indium tin oxide (ITO). The cathode may have a single layer structure or a multilayer structure.

(6) Other materials for each layer constituting the organic light-emitting device Known materials can be used for each layer other than the electron injection layer. An organic compound can be used as such a material. Such materials may be low molecules or polymers.

(About the anode)
As a constituent material of the anode, a material having a work function as large as possible (for example, a work function of 4.5 eV or more and 5.5 eV or less) is preferable. For example, simple metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, tungsten, etc., or an alloy combining them, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), zinc oxide Metal oxides such as indium can be used. In addition, conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used.

  These electrode materials may be used alone or in combination of two or more. Moreover, the anode may be composed of a single layer or a plurality of layers.

(About hole transport layer and / or hole injection layer)
The material possessed by the hole transport layer and the hole injection layer (in addition to the electron blocking layer) may be appropriately selected in consideration of the required hole transport property and the injection property from the anode. In order to prevent deterioration of film quality such as crystallization in the organic light emitting device, it is preferable to select a material having a high glass transition temperature. Low molecular and high molecular weight materials having hole injection and transport performance include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly (vinylcarbazole), poly (thiophene), Other examples include conductive polymers. Specific examples of the compound used as the hole injecting and transporting material are shown below, but the present invention is not limited to these.

(About the light emitting layer)
The light emitting layer of the organic light emitting device according to the present invention may be composed only of a light emitting material, but preferably includes a light emitting material and a compound different from the light emitting material. The light-emitting material included in the light-emitting layer refers to a material called a light-emitting layer guest or a light-emitting layer dopant. The light emitting material included in the light emitting layer refers to a so-called light emitting layer host. That is, the light emitting layer preferably has a host and a guest.

  The light-emitting layer host is a compound that does not aggregate the guest around the light-emitting layer guest, that is, exists as a matrix, mainly for transporting carriers to the light-emitting layer guest or for providing excitation energy to the light-emitting layer guest. It is a compound of this.

  The light emitting layer guest is a compound that emits main light and is also called a light emitting dopant.

  The weight ratio of the light emitting layer host is larger than 50 wt% and not more than 99.9 wt% when the total weight ratio of the constituent materials of the light emitting layer is 100 wt%.

  The weight ratio of the light emitting layer guest is 0.01% by weight or more and 50% by weight or less, preferably 0.1% by weight or more and 20% by weight or less when the total weight ratio of the constituent materials of the light emitting layer is 100% by weight. % Or less. From the viewpoint of preventing concentration quenching of the light emitting layer guest, the concentration of the light emitting layer guest is particularly preferably 10% by weight or less.

  In the present invention, when the light emitting layer guest has a host, the light emitting layer guest may be present uniformly throughout the light emitting layer, and for example, the concentration thereof is gradient in the direction from the anode to the cathode. Also good. In addition, the light emitting layer guest may be included in a specific region in the light emitting layer, and a region having only the light emitting layer host not including the light emitting layer guest may be provided.

  Furthermore, the light emitting layer may have a light emission assist material or a charge injection material in addition to the light emitting layer guest and the light emitting layer host. The light emission assist material is a compound whose weight ratio (concentration) in the light emitting layer is smaller than that of the light emitting layer host material. The charge injection material is a carrier from the carrier transport layer (layer adjacent to the light emitting layer) to the light emitting layer. A compound that aids infusion.

  Examples of the light-emitting material include condensed compounds such as fluoranthene derivatives, fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, and rubrene, organic compounds such as quinacridone derivatives, coumarin derivatives, and stilbene derivatives, and tris (8 -Quinolinolate) Organo aluminum complexes such as aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, various organometallic complexes, poly (phenylene vinylene) derivatives, poly (fluorene) derivatives, poly (phenylene) ) Derivatives such as polymer compounds.

  The fluoranthene derivative refers to a compound in which a substituent is provided on the fluoranthene skeleton, and a compound in which a condensed ring is provided on the fluoranthene skeleton. The same applies to other derivatives.

  Although the specific example of the compound used as a luminescent material is shown below, of course, it is not limited to these.

  Examples of the light emitting layer host and light emission assist material include aromatic hydrocarbon compounds or derivatives thereof, carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris (8-quinolinolato) aluminum, and organic beryllium complexes. be able to.

  Specific examples of the light emitting layer host or the light emission assisting material included in the light emitting layer are shown below, but of course not limited thereto.

(Formation of organic compound layer)
Examples of the organic compound layer (hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) included in the organic light emitting device according to the present invention are shown below. Formed by the method.

  For example, it is a formation method by a dry process such as a vacuum deposition method, an ionization deposition method, sputtering, or plasma. In addition, there is a formation method by a wet process in which a layer is formed by applying a solution by a known application method (for example, spin coating, dipping, casting method, LB method, ink jet method, etc.) after dissolving in a solvent and drying the solvent. be able to.

  Here, when a layer is formed by a vacuum deposition method, a solution coating method, or the like, crystallization or the like hardly occurs and the temporal stability is excellent. Moreover, when forming into a film by the apply | coating method, a film | membrane can also be formed combining with a suitable binder resin.

  Examples of the binder resin include, but are not limited to, polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicon resin, urea resin, and the like. .

  Moreover, these binder resins may be used alone as a homopolymer or a copolymer, or may be used in combination of two or more. Furthermore, you may use together additives, such as a well-known plasticizer, antioxidant, and an ultraviolet absorber, as needed.

(Other forms of organic light-emitting elements)
The organic light emitting device according to the present invention may be configured to extract emitted light from either side of the pair of electrodes.

  The organic light emitting element is disposed on a substrate such as a glass substrate or a silicon substrate, but a so-called bottom emission type in which light is extracted from an electrode closer to the substrate out of a pair of electrodes, or a so-called top in which light is extracted from the opposite side of the substrate. Emission type may be used. In the case of the bottom emission type, light passes through the transparent substrate. In the case of the top emission type, the substrate may be transparent or opaque, and a silicon substrate can be used.

  Alternatively, a double-sided extraction type in which light is extracted from the substrate side and the opposite side of the substrate may be used.

(7) Use of organic light-emitting device of the present invention The organic light-emitting device according to the present invention can be used for a display unit of a display device and a light source unit of a lighting device. In addition, an exposure light source for writing an electrostatic latent image on a photosensitive drum of an electrophotographic image forming apparatus such as a laser beam printer or a copying machine, a backlight of a liquid crystal display device, a light emission having a color filter in a white light source There are applications such as equipment. Examples of the color filter include filters that transmit three colors of red, green, and blue.

  The display device has a plurality of pixels. At least one of the plurality of pixels includes the organic light-emitting element according to the present invention and an active element (connected to the organic light-emitting element. Examples of the active element include a switching element and an amplifying element. Specifically, The anode or cathode of the organic light emitting device and the drain electrode or source electrode of the transistor are electrically connected, and the active device controls the light emission and non-light emission of each pixel.

  The display device can be used as an image display device such as a PC.

  The transistor may include a semiconductor material such as silicon in its active region, an organic semiconductor material that is an organic compound, or an oxide semiconductor.

  An example of the transistor is a TFT element, and this TFT element is provided on, for example, an insulating surface of a substrate.

  The display device may include a plurality of pixels, and each pixel may be disposed across a separation region in which an element isolation film such as a bank is disposed in the in-plane direction. The organic light emitting device included in each pixel has the electron injection layer according to the present invention. The electron injection layer may be continuously arranged across a separation region between a certain organic light emitting element and an organic light emitting element adjacent thereto. It can be said that the pixels have an electron injection layer that is continuously common. Specifically, it may be arranged at a time in a region corresponding to the entire display region of the display device by a manufacturing method such as vapor deposition.

  The display device includes an image input unit that inputs image information from an area CCD, linear CCD, memory card, or the like, an information processing unit that processes the image information, and a display unit that displays the input image. But you can.

  Specifically, the information processing apparatus is an imaging apparatus such as a digital camera or a digital video camera or an ink jet printer. The display device according to the present embodiment is arranged in the rear operation unit and viewfinder unit of the imaging apparatus. In addition, the display device according to the present embodiment is disposed in the operation unit of the ink jet printer. A display unit included in such an information processing apparatus may have a touch panel function. The driving method of the touch panel function is not particularly limited.

  The display device may be used for a display unit of a multifunction printer.

  When the display device is an image display device used for a PC monitor or the like, the organic light emitting element included in the pixel (sub-pixel) may emit either red, blue or green, or three primary colors such as yellow Other colors may emit light. And it is not limited to such a color, The organic light emitting element concerning this Embodiment can be used. In addition, the organic light emitting device according to the present embodiment may be an organic light emitting device in which one light emitting layer has a plurality of types of light emitting materials having different emission colors and emits white light by color mixture. For example, red, green, and blue color filters are arranged for each organic light emitting element, and as a result, the organic light emitting element according to the present embodiment may be used as an organic light emitting element of an image display device capable of full color display.

  The lighting device is, for example, a device that illuminates a room. The lighting device may be a lighting device that emits white light (color temperature is 4200 K), day white color (color temperature is 5000 K), or any other color from blue to red.

  The lighting device includes the organic light emitting device of the present invention and an AC / DC converter circuit connected to the organic light emitting device. In addition, this illuminating device may further have a color filter.

  The lighting device may have a heat dissipation part. The heat dissipating part is a heat dissipating part that releases the heat in the lighting device to the outside. Examples of the heat dissipating part include metals and fluid silicon having a high specific heat ratio. Heat can be dissipated by fluid convection.

  The image forming apparatus is an image forming apparatus having a photosensitive member, a charging unit that charges the surface of the photosensitive member, an exposure unit that exposes the photosensitive member, and a developing unit that applies a developer to the surface of the photosensitive member. Here, the exposure device provided in the image forming apparatus includes the organic light emitting device of the present invention.

  The organic light-emitting device according to this embodiment can be used as a constituent member of an exposure apparatus that exposes a photoreceptor. In the exposure apparatus, for example, a plurality of organic light emitting elements according to the present embodiment may be arranged and arranged. Specifically, it is an exposure apparatus in which a plurality of organic light emitting elements are arranged in a line along the long axis direction of the photoreceptor.

  Next, the image display apparatus will be described with reference to the drawings. FIG. 2 is a schematic cross-sectional view showing an example of an image display device having two organic light emitting elements and two TFT elements connected in correspondence with the respective organic light emitting elements.

  The image display device 1 in FIG. 2 includes a substrate 11 made of glass or the like and a moisture-proof film 12 for protecting the TFT element or the organic compound layer on the substrate 11. Reference numeral 13 denotes a metal gate electrode 13. Reference numeral 14 denotes a gate insulating film 14 and reference numeral 15 denotes a semiconductor layer.

  The TFT element 18 includes a semiconductor layer 15, a drain electrode 16, and a source electrode 17. An insulating film 19 is provided on the TFT element 18. The anode 21 and the source electrode 17 constituting the organic light emitting element are connected via the contact hole 20.

  The method of electrical connection between the electrodes (anode and cathode) included in the organic light emitting element and the electrodes (source electrode and drain electrode) included in the TFT is not limited to the mode shown in FIG. That is, it is only necessary that either one of the anode or the cathode is electrically connected to either the TFT element source electrode or the drain electrode.

  In the image display device 1 of FIG. 2, the multiple organic compound layers are illustrated as one layer, but the organic compound layer 22 may be a plurality of layers. On the cathode 23, the 1st protective layer 24 and the 2nd protective layer 25 for suppressing deterioration of an organic light emitting element are provided.

  When the image display device 1 in FIG. 2 is an image display device that emits white light, the light emitting layer included in the organic compound layer 22 may be a layer formed by mixing a red light emitting material, a green light emitting material, and a blue light emitting material. Alternatively, a layered light emitting layer in which a layer made of a red light emitting material, a layer made of a green light emitting material, and a layer made of a blue light emitting material are laminated may be used. Furthermore, a mode in which domains are formed in one light emitting layer by arranging a layer made of a red light emitting material, a layer made of a green light emitting material, and a layer made of a blue light emitting material side by side. In addition, a structure in which one light emitting layer has light emitting materials having different light emission colors that have complementary colors may be used, or different light emitting layers may be stacked vertically or horizontally. Arranging a plurality of light emitting layers side by side means that each of the plurality of light emitting layers is in contact with an organic compound layer adjacent to the light emitting layer. The layer adjacent to the light emitting layer is a carrier injection layer or the like and is not a light emitting layer.

  In the image display device 1 of FIG. 2, a transistor is used as a switching element, but an MIM element may be used as a switching element instead.

  The transistor is not limited to a transistor using a single crystal silicon wafer, and may be a thin film transistor having an active layer on an insulating surface of a substrate. Thin film transistor using single crystal silicon as active layer, thin film transistor using non-single crystal silicon such as amorphous silicon or microcrystalline silicon as active layer, non-single crystal oxidation such as indium zinc oxide or indium gallium zinc oxide as active layer A thin film transistor using a physical semiconductor may be used. The thin film transistor is also called a TFT element.

  The transistor included in the image display device 1 of FIG. 2 may be formed in a substrate such as a Si substrate. Here, being formed in the substrate means that a transistor is manufactured by processing the substrate itself such as a Si substrate.

  Whether or not the transistor is provided in the substrate is selected depending on the definition. For example, in the case of 1 inch with a definition of about QVGA, it is preferable to provide an organic light emitting element on the Si substrate.

  The organic light emitting device according to the present invention may have a switching element for controlling light emission of the organic light emitting element. The switching element connected to the organic light emitting element may have an oxide semiconductor in its active region. The oxide semiconductor may be amorphous, crystalline, or a mixture of both.

  The crystal may be a single crystal, a microcrystal, or a crystal in which a specific axis such as the C axis is oriented, or a mixture of at least any two of them.

  The organic light emitting device having such a switching element may be used as an image display device in which each organic light emitting element is provided as a pixel, or may be used as an illumination device. Further, it may be used as an exposure light source for exposing a photoreceptor of an electrophotographic image forming apparatus such as a laser beam printer or a copying machine.

  FIG. 2 is a schematic diagram of the image forming apparatus 26 according to the present invention. The image forming apparatus includes a photoreceptor, an exposure light source, a developing unit, a charging unit, a transfer device, a transport roller, and a fixing device.

  Light 29 is emitted from the exposure light source 28, and an electrostatic latent image is formed on the surface of the photoreceptor 27. This exposure light source has the organic light emitting device according to the present invention. The developing device 30 has toner or the like. The charging unit 31 charges the photoconductor. The transfer device 32 transfers the developed image to the recording medium 34. The conveyance roller 33 conveys the recording medium 34. The recording medium 34 is, for example, paper. The fixing device 35 fixes the image formed on the recording medium.

  FIGS. 3A and 3B are schematic views showing a state in which a plurality of light emitting portions 36 are arranged on the exposure light source 28 on a long substrate. The organic light emitting elements are arranged in a line along the long axis direction of the photoreceptor. An arrow 37 represents the column direction in which the organic light emitting elements are arranged. This row direction is the same as the direction of the axis around which the photoconductor 27 rotates. This direction can also be referred to as the major axis direction of the photoreceptor.

  FIG. 3A shows a form in which the light emitting portions are arranged along the long axis direction of the photosensitive member. FIG. 3B shows a form different from that shown in FIG. 3A, in which the light emitting units are alternately arranged in the column direction in each of the first column and the second column. The first column and the second column are arranged at different positions in the row direction.

  In the first row, a plurality of light emitting units are arranged at intervals. The second row has light emitting portions at positions corresponding to the intervals between the light emitting portions of the first row. That is, a plurality of light emitting units are also arranged at intervals in the row direction.

  The arrangement in FIG. 3B can be paraphrased as, for example, a state in which the elements are arranged in a lattice, a state in which the elements are arranged in a staggered pattern, or a checkered pattern.

  FIG. 4 is a schematic diagram of a lighting device according to the present invention. The lighting device includes a substrate, an organic light emitting element 38, and an AC / DC converter circuit 39. Moreover, you may have a thermal radiation part not shown in the back surface side with respect to the board | substrate surface in which the organic light emitting element is mounted, for example.

  As described above, stable driving for a long time is possible by driving a device using the organic light-emitting element of the present invention.

[Synthesis Example 1] (Synthesis of Exemplified Compound C101)
With reference to Non-Patent Document 1, C101 was synthesized by the following synthesis scheme.

In a nitrogen atmosphere, the following reagents and solvents were put into a 100 mL eggplant flask.
Bis (cyclopentadienyl) cobalt (III) hexafluorophosphate: 200 mg (0.60 mmol)
Dehydrated diethyl ether: 36 mL

While stirring at room temperature, 1.20 mL (1.20 mmol) of 1.0 M phenyllithium in cyclohexane / diethyl ether was added to the reaction dispersion. After 30 seconds, dry ice pieces were added to the reaction solution, and water was added to stop the reaction. Subsequently, the organic phase is separated by a liquid separation operation, the aqueous phase is extracted twice with dichloromethane, and the combined organic phases are washed with water, dried over sodium sulfate and concentrated to obtain a crude product. It was. Next, this crude product was recrystallized from hexane to obtain 132 mg of reddish brown crystals of Exemplified Compound C101 (yield 83%). Subsequently, sublimation purification was performed partially on conditions of 10 ⁻³ Pa and 100 ° C., thereby obtaining granular reddish brown crystals of Illustrative Compound C101 with high purity.

The obtained exemplary compound C101 was identified by NMR measurement.
¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 7.12 (t, 2H), 7.04 (t, 1H), 6.79 (d, 2H), 5.28 (t, 2H) , 4.81 (s, 5H), 3.85 (t, 1H), 2.94 (q, 2H).

Furthermore, the obtained exemplary compound C101 was subjected to CV measurement to measure the first oxidation potential. CV measurement was performed in a DMF solution of 0.1 M tetrabutylammonium perchlorate, the reference electrode was Ag / AgCl, the counter electrode was Pt, the working electrode was glassy carbon, and the insertion speed was 0.1 V / s. Measured with As a measuring device, model 660C manufactured by ALS, an electrochemical analyzer was used. The obtained first oxidation potential is Fc / Fc based on −0.065 V (vs. Ag / Ag ⁺ ), which is the potential of ferrocene / ferrocenium (hereinafter Fc / Fc ⁺ ) obtained by the same CV measurement. ^When converted to ⁺ standard, it was −0.73 V (vs. Fc / Fc ⁺ ).

  Furthermore, even when the obtained exemplary compound C101 was allowed to stand in the atmosphere at room temperature for 12 hours, the color and state of the crystals did not change at all and were stable without being oxidized or decomposed by oxygen.

  [Synthesis Example 2] (Synthesis of Exemplified Compound C111)

In a nitrogen atmosphere, the following reagents and solvents were put into a 100 mL eggplant flask.
4-iodobiphenyl: 196 mg (0.70 mmol)
Dehydrated diethyl ether: 20 mL

While stirring this reaction solution at −78 ° C., 0.44 mL (0.70 mmol) of 1.6M n-butyllithium hexane solution was added dropwise, and then the reaction solution was heated to room temperature. . 117 mg (0.35 mmol) of bis (cyclopentadienyl) cobalt (III) hexafluorophosphate was added to the resulting cloudy solution of biphenyl-4-yllithium, and after 1 minute, a piece of dry ice was added to the reaction solution. After the addition, water was added to stop the reaction. Subsequently, the organic phase is separated by a liquid separation operation, the aqueous phase is extracted twice with dichloromethane, and the combined organic phases are washed with water, dried over sodium sulfate and concentrated to obtain a crude product. It was. Next, this crude product was recrystallized with hexane to obtain 70 mg of brown powder of Exemplified Compound C111 (yield 58%). Subsequently, by performing sublimation purification under conditions of 10 ⁻³ Pa and 120 ° C., a reddish brown crystal of high purity exemplary compound C111 was obtained.

The obtained exemplary compound C111 was identified by NMR measurement.
¹ H-NMR (400 MHz, CDCl ₃ ) δ (ppm): 7.48 (d, 2H), 7.39-7.34 (m, 4H), 7.29 (m, 1H), 6.86 ( d, 2H), 5.31 (t, 2H), 4.82 (s, 5H), 3.89 (t, 1H), 2.97 (q, 2H).

  Furthermore, even when the obtained exemplary compound C111 was allowed to stand at room temperature in the atmosphere for 12 hours, the color and state of the crystals did not change at all and were stable without oxidation or decomposition by oxygen.

[Synthesis Examples 3 to 5]
In the synthesis scheme of Synthesis Example 1 or 2, the cobalt monovalent complex shown in Table 1 was synthesized by the same synthesis method as in Synthesis Example 1 or 2, except that the compound used as the synthesis raw material was changed to the compound shown in Table 3 below. did. About the obtained cobalt monovalent complex, it identified similarly to the cobalt monovalent complex obtained in the synthesis examples 1 and 2, and confirmed the structure.

  As for the cobalt monovalent complexes obtained in Synthesis Examples 3 to 5, as in Synthesis Examples 1 and 2, any color or state of the complex does not change even if it is left in the atmosphere at room temperature for 12 hours. In addition, oxidation and decomposition by oxygen did not occur and was stable.

[Comparative Examples 1 to 3]
For the comparative compounds CoCp ₂ , CoCp ^* ₂ and FeCp ^* ₂ shown in Table 2 below, the first oxidation potential (vs. Fc / Fc ⁺ ) was measured by CV measurement using the same measurement method as for the exemplary compound C101 of Synthesis Example 1. It was measured. In addition, each comparative compound was allowed to stand at room temperature for 1 hour in the same manner as in Synthesis Example 1, and then the change in state was examined. The results are shown in Table 2 below together with the results of Synthesis Example 1.

Cobaltcenes of cobalt divalent complexes, CoCp ₂ and CoCp ^* ₂ , which are 19-electron complexes, have a very low first oxidation potential and a high electron donor property, but are allowed to stand at room temperature in the atmosphere for 12 hours. Then, the crystal color changes from black purple to black.

This is because it is unstable with respect to oxygen and easily oxidized. Here, according to Non-Patent Document 2, the reduction potential (O ₂ / O ₂ ⁻ ) of oxygen is −1.22 V (vs. Fc / Fc ⁺ ) in a DMF solvent. A compound having a lower first oxidation potential is considered to be easily oxidized by atmospheric oxygen. That is, it is considered that the compounds of Comparative Examples 1 and 2 were oxidized by oxygen in the atmosphere.

On the other hand, FeCp ^* ₂ is an iron divalent complex ferrocene, which is a stable 18-electron complex, and its first oxidation potential is relatively high, and it does not change at all even if it is left at room temperature for 12 hours. It was stable. However, since the first oxidation potential is high, it is considered that the electron donor property is insufficient.

[Example 1]
In this example, an organic light emitting device having a structure in which an anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode are provided in this order on a substrate is as follows. Produced.

  First, an ITO film was formed on a glass substrate, and an ITO electrode (anode) was formed by performing a desired patterning process. At this time, the film thickness of the ITO electrode was 100 nm. The substrate on which the ITO electrode was thus formed was used as an ITO substrate in the following steps.

An organic light emitting device was obtained by continuously forming an organic compound layer and electrodes shown in Table 3 on the ITO substrate. However, at this time, for the purpose of comparing the stability of the n-type dopant with respect to oxygen, after forming the electron injection layer, the device in the process of being stacked up to the electron injection layer was once taken out of the vacuum chamber. Thereafter, after being exposed to the air for 15 minutes and then returned to the vacuum chamber again, Al serving as a cathode was deposited on the electron injection layer. At this time, the electrode area of the opposing electrodes (anode, cathode) was set to 3 mm ² .

About the obtained element, the current-voltage characteristic measurement using Hured Packard's microammeter 4140B and the light emission luminance measurement using Topcon BM7 were performed, and the characteristic of the element was measured and evaluated. In this example, the current value at an applied voltage of 6 V was 10.3 mA / cm ² , and red light emission by RD1 was confirmed.

[Examples 2 to 7, Comparative Examples 4 to 7]
In Example 1, the compounds used as the hole blocking layer (HBL), the electron transport layer (ETL), the electron injection layer host (EIL-HOST) and the n-type dopant (n-dopant) are shown in Table 4 below. Changed to compound. Except for this, an organic light emitting device was fabricated in the same manner as in Example 1. In Example 2, no atmospheric exposure was performed for 15 minutes after the formation of the electron injection layer, and no n-type dopant was used in Comparative Example 7. About the obtained element, the characteristic of the element was measured and evaluated in the same manner as in Example 1. Table 4 shows the measurement results.

Both of the organic light-emitting devices of Comparative Examples 4 and 5 have a remarkably low current value at an applied voltage of 6 V compared to the organic light-emitting devices of Examples, and are the same as the organic light-emitting device of Comparative Example 7 that does not use an n-type dopant. The current value was about. This is because CoCp ₂ and CoCp ^* ₂ used for the electron injection layer are unstable to oxygen because their first oxidation potential is too low. That is, it is considered that CoCp ₂ and CoCp ^* ₂ are transformed into oxides due to exposure to the atmosphere after formation of the electron injection layer and lose their electron donor properties, and do not function effectively as n-type dopants in the electron injection layer. .

Further, the organic light emitting device of Comparative Example 6 also has a remarkably low current value at an applied voltage of 6 V compared to the organic light emitting device of Example, and is comparable to the organic light emitting device of Comparative Example 7 that does not use an n-type dopant. The current value. This is because the electron injection property of the light-emitting element is low because the first oxidation potential of FeCp ^* ₂ used for the electron injection layer is high and the electron donor property is insufficient.

  Furthermore, in Comparative Examples 4 to 6, it is difficult to control the doping concentration of the n-type dopant in the electron injection layer to 10 vol%, and the concentration greatly varies in the range of about 5 to 15 vol% during film formation. Oops. This is because it was difficult to form a film by heat evaporation because the volatility of the n-type dopant used was too high. Furthermore, when depositing Al as the cathode on the electron injection layer, there is a possibility that the highly volatile n-type dopant was lost by re-evaporation from the inside of the electron injection layer after film formation due to large radiant heat. .

  On the other hand, Examples 1 and 2 of the present invention show good electron injection properties with a high current value at an applied voltage of 6 V in both organic light-emitting elements, regardless of the presence or absence of atmospheric exposure after formation of the electron injection layer. Good red light emission was obtained. This shows that the cobalt monovalent complex C101 used in Examples 1 and 2 effectively acts as an n-type dopant even in the electron injection layer after exposure to the atmosphere as an n-type dopant stable to oxygen. .

  Similarly, in the organic light emitting devices of Examples 3 to 7 of the present invention, since a cobalt monovalent complex that is stable against oxygen is used as the n-type dopant in the electron injection layer, it is exposed to the atmosphere after the electron injection layer is formed. Also showed good electron injection properties.

  In Examples 1 to 7 of the present invention, it was possible to deposit an electron injection layer with good control at a desired dope concentration with respect to heat deposition of a cobalt monovalent complex. Further, the decrease in luminance after 100 hours was within 25% from the initial luminance in any of the organic light emitting devices of the examples. From this, it is considered that a stable organic light-emitting element with low luminance deterioration can be provided even when light is emitted for a long time.

18 TFT element 21 Anode 22 Organic compound layer 23 Cathode

Claims (15)

An organic light emitting device having an anode, a cathode, and a light emitting layer disposed between the anode and the cathode,
An organic compound layer disposed between the cathode and the light emitting layer;
The organic compound layer has a cobalt monovalent complex represented by the following general formula [1].

In the formula [1], X _{1 to} X ₉ each represent a hydrogen atom or a methyl group. Ar represents a substituted or unsubstituted aromatic hydrocarbon group. 2. The organic light-emitting device according to claim 1, wherein Ar in the formula [1] is selected from an aromatic hydrocarbon group represented by the following formula [2].

In the formula [2], R _{1 to} R ₃₉ each represents a hydrogen atom or a substituent. The substituent represents a halogen atom, an alkyl group which may have a halogen atom, or a cyano group. * Represents a bond with the cyclopentadiene ring in the general formula [1]. The organic light-emitting device according to claim 1, wherein X _{1 to} X ₉ in the formula [1] are all hydrogen atoms.   The Ar in the formula [1] is a phenyl group, a biphenyl-4-yl group, a naphthalen-2-yl group, or a 9,9-dimethylfluoren-2-yl group. Organic light-emitting device as described in any one of these. The organic compound layer has a compound different from the cobalt monovalent complex,
5. The weight ratio of the different compound is 20 wt% or more and 99.9 wt% or less when the weight ratio of the whole organic compound layer is 100 wt%. The organic light emitting element as described in any one.   The another type of compound is any one of an oxadiazole derivative, an oxazole derivative, a pyrazine derivative, a triazole derivative, a triazine derivative, a quinoline derivative, a quinoxaline derivative, a phenanthroline derivative, an organoaluminum complex, a condensed ring compound, or an anthraquinone derivative. The organic light emitting device according to claim 5.   The organic light-emitting device according to claim 1, further comprising a second organic compound layer disposed between the light-emitting layer and the organic compound layer. Having a plurality of pixels,
A display device, wherein at least one of the plurality of pixels includes the organic light-emitting element according to claim 1 and an active element connected to the organic light-emitting element. . A separation area between the pixel and the pixel;
The display device according to claim 8, wherein the organic compound layer is continuously arranged in a pixel and a separation region. The active element is a transistor;
The display device according to claim 8, wherein the transistor includes an oxide semiconductor in an active region thereof. A display for displaying an image;
An input unit for inputting image information; and an information processing unit for processing the image information;
The information processing apparatus, wherein the display unit is the display apparatus according to any one of claims 8 to 10. An organic light emitting device according to any one of claims 1 to 7,
And an AC / DC converter circuit connected to the organic light-emitting element. A lighting device comprising the organic light-emitting element according to any one of claims 1 to 7 and a heat dissipation part,
The radiating device, wherein the heat radiating portion is a heat radiating portion that releases heat in the device to the outside. A photoreceptor,
A charging unit for charging the surface of the photoreceptor;
An exposure unit for exposing the photoreceptor;
An image forming apparatus having a developing section for applying a developer to the surface of the photoreceptor,
An image forming apparatus, wherein the exposure unit includes the organic light emitting device according to claim 1. An exposure apparatus for exposing a photoreceptor,
The exposure apparatus has a plurality of organic light-emitting elements according to any one of claims 1 to 7,
An exposure apparatus, wherein the plurality of organic light emitting elements are arranged in a line along a major axis direction of the photoconductor.