Phenanthroline compound and organic electroluminescent element

Abstract

A phenanthroline compound represented by general formula (A) has a high refractive index and a low attenuation coefficient with respect to a wavelength of 450-750 nm, and thus is useful as a material for a coating layer of an organic EL element. In the formula, Ar represents an unsubstituted heteroaryl group, L1 and L2 represent a single bond, an arylene group, or a heteroarylene group, X represents a methylene group, an oxygen atom, or a sulfur atom, and A represents an unsubstituted phenanthroline group.

Description

TECHNICAL FIELD

[0001] The present application relates to a compound suitable for a self-light-emitting electronic element for various display devices, particularly a phenanthroline compound suitable for an organic electroluminescent element (hereinafter, simply referred to as an organic EL element), and an organic EL element, an electronic element, and an electronic device using the same. BACKGROUND

[0002] Since the organic EL element is a self-light-emitting element, and the organic EL element is bright and excellent in visibility as compared with a liquid crystal element, clear display can be provided, and thus, the organic EL element has been actively researched.

[0003] In 1987, C. W. Tang et al. of the Eastman Kodak Company made an organic EL element using an organic material practical by developing a layered structure element in which various functions are assigned to each material. The above researchers layered a fluorescent body capable of transporting electrons and an organic material capable of transporting holes, injected charges of both into a layer of the fluorescent body, and caused the fluorescent body to emit light, whereby a luminance of 1000 cd / m2 was obtained at a voltage of 10 V or less (Patent Document 1). 2 The above is high in luminance (for example, refer to Patent Documents 1 and 2).

[0004] Up to now, many improvements have been made for practical use of the organic EL element, and the functions of each layer of the layered structure are further subdivided, and an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, a cathode are sequentially provided on a substrate, a light-emitting element of a bottom emission structure which emits light from the bottom is formed, and thus, high efficiency and durability are achieved (for example, refer to Non-Patent Document 1).

[0005] In recent years, a light-emitting element of a top emission structure which emits light from the top using a metal having a high work function for an anode has been used. In a bottom emission structure which extracts light from the bottom of a pixel circuit, the area of a light-emitting portion is limited, and in contrast to this, in a light-emitting element of a top emission structure, light is extracted from the top and is not blocked by a pixel circuit, and thus, has an advantage that a wide light-emitting portion can be used. In a light-emitting element of a top emission structure, a cathode uses a semi-transparent electrode such as LiF / Al / Ag (for example, refer to Non-Patent Document 2), Ca / Mg (for example, refer to Non-Patent Document 3), LiF / MgAg.

[0006] In such a light-emitting element, when light emitted in the light-emitting layer is incident on another film, if the incident angle is equal to or higher than a certain angle, the light is totally reflected at the interface between the light-emitting layer and the other film. Thus, only a part of the emitted light can be used. In recent years, in order to improve the light extraction efficiency, a light-emitting element in which a "capping layer" having a high refractive index is provided outside a semitransparent electrode having a low refractive index has been proposed (see, for example, Non-Patent Document 2 and Non-Patent Document 3).

[0007] As the effect of the capping layer in a light-emitting element of a top emission structure, in a light-emitting element in which Ir(ppy)3 is used as a light-emitting material, the current efficiency is 38 cd / A in the case where no capping layer is provided, and in a light-emitting element in which ZnSe having a film thickness of 60 nm is used as a capping layer, an efficiency improvement of about 1.7 times, i.e., 64 cd / A, is observed. Furthermore, it is shown that the maximum point of the transmittance of the semitransparent electrode and the capping layer and the maximum point of the efficiency do not necessarily coincide with each other, and that the maximum point of the light extraction efficiency depends on the interference effect (see, for example, Non-Patent Document 3).

[0008] A technique in which a metal mask having high precision is used for formation of a capping layer has been proposed in the past, but when used in a high-temperature condition, there is a problem in that the metal mask is deformed by heat, which leads to a decrease in alignment precision. Thus, ZnSe having a melting point of 1100 °C or higher cannot be deposited at an accurate position by a metal mask having high precision, and there is a possibility that an adverse effect on a light-emitting element is caused (see, for example, Non-Patent Document 3). Furthermore, even when film formation is performed by a sputtering method, an adverse effect on a light-emitting element is caused, and thus it is not suitable to use a capping layer in which an inorganic substance is used as a material.

[0009] Further, a technique in which tris(8-hydroxyquinoline)aluminum (hereinafter referred to as Alq3) is used as a capping layer for adjusting the refractive index has been proposed (see, for example, Non-Patent Document 2). However, Alq3 is known as an organic EL material which is usually used as a green light-emitting material or an electron-transporting material, and has a weak absorption near 450 nm which is close to the emission wavelength of a blue light-emitting material, and thus in the case of a blue light-emitting element, there are problems such as a decrease in color purity and a decrease in light extraction efficiency.

[0010] Prior Art Documents

[0011] Patent Documents

[0012] Patent Document 1: US5792557

[0013] Patent Document 2: US5639914

[0014] Patent Document 3: International Publication No. 2014 / 009310

[0015] Patent Literature 4: US2014 / 0225100A1

[0016] Non-Patent Literature

[0017] Non-Patent Literature 1: Extended Abstracts of the 9th (2001) Application Physics Society, pp. 55-61

[0018] Non-Patent Literature 2: Appl. Phys. Lett., 78, 544 (2001)

[0019] Non-Patent Literature 3: Appl. Phys. Lett., 82, 466 (2003)

[0020] Non-Patent Literature 4: Tetrahedron, 58, 9633 (2002)

[0021] Non-Patent Literature 5: Appl. Phys. Lett., 98, 083302 (2011) SUMMARY

[0022] As described above, it is effective to improve the light extraction efficiency of an organic EL element by using an organic covering layer that exhibits a high refractive index in the light emission wavelength region of the element. However, the refractive index of the organic covering materials proposed so far in the light emission wavelength region of the organic EL element is not sufficiently high, and in fact, the efficiency of the element cannot be sufficiently improved.

[0023] Therefore, the present inventors and others have conducted intensive research in order to solve this conventional technical problem, with the aim of providing an organic compound having a high refractive index and a low attenuation coefficient with respect to light having a wavelength of 450 nm to 750 nm. Furthermore, intensive research has been conducted with the aim of providing an organic EL element having a high efficiency.

[0024] Means for solving the technical problem

[0025] As a result of intensive research conducted by the present inventors and others in order to achieve the above-mentioned object, it was found that a phenanthroline compound has excellent stability and durability in a thin film state, and furthermore, by imparting a specific aromatic ring group or aromatic heterocyclic group to this phenanthroline compound, a material having a high refractive index and a low attenuation coefficient in the range of wavelengths of 450 nm to 750 nm can be obtained. Furthermore, it was found that by using such a phenanthroline compound in the material of a covering layer, an organic EL element having a high light emission efficiency and a long lifetime can be realized. The present application was proposed based on these insights, and specifically has the following structure.

[0026] 1) A phenanthroline compound represented by the following general formula (A).

[0027] [Chemical Formula 1]

[0028]

[0029] wherein Ar represents an unsubstituted heteroaryl group,

[0030] L1and L2each independently represent a single bond, an arylene group or a heteroarylene group, at least one hydrogen atom of the arylene group and the heteroarylene group can be substituted with an atom or a group selected from the group consisting of a heavy hydrogen atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkyloxy group, an aryl group and a heteroaryl group.

[0031] X represents a methylene group, an oxygen atom or a sulfur atom, at least one hydrogen atom of the methylene group can be substituted with an atom or a group selected from the group consisting of a heavy hydrogen atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkyloxy group, an aryl group and a heteroaryl group.

[0032] A represents an unsubstituted phenanthroline group.

[0033] 2) The phenanthroline compound according to 1), wherein A in the general formula (A) is an unsubstituted 1,10-phenanthroline group. Thereby, it becomes a 1,10-phenanthroline compound.

[0034] 3) The phenanthroline compound according to 2), wherein the general formula (A) is the following general formula (B).

[0035] [Chemical Formula 2]

[0036]

[0037] A in the general formula (B) represents an unsubstituted 1,10-phenanthroline group. Ar, L1, L2and X are as defined in the general formula (A).

[0038] 4) The phenanthroline compound according to 3), wherein X in the general formula (B) is a methylene group, at least one hydrogen atom of the methylene group can be substituted with an atom or a group selected from the group consisting of a heavy hydrogen atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkyloxy group, an aryl group and a heteroaryl group.

[0039] 5) The phenanthroline compound according to 4), wherein L1and L2in the general formula (B) are a single bond or an unsubstituted 1,4-phenylene group.

[0040] 6) The phenanthroline compound according to 5), wherein Ar in the general formula (B) is an unsubstituted quinoline group, an unsubstituted isoquinoline group, an unsubstituted benzoxazolyl group, an unsubstituted benzothiazolyl group, an unsubstituted oxazolopyridyl group, an unsubstituted benzofuranyl group or an unsubstituted benzothiophenyl group.

[0041] 7) An organic EL device comprising at least an anode electrode, a hole transport layer, a light emitting layer, an electron transport layer, a cathode electrode, and a covering layer in this order, wherein the covering layer contains the phenanthroline compound represented by the general formula (A) described in 1).

[0042] 8) The organic EL element according to 7), wherein the refractive index of a vapor-deposited film obtained by vacuum vapor-depositing the phenanthroline compound represented by the general formula (A) onto a silicon substrate with a film thickness of 80 nm is 1.70 or more in a wavelength range of greater than 450 nm and less than 750 nm measured at room temperature (25°C).

[0043] 8') The organic EL device according to 7), wherein the cover layer has a thickness of 30 nm to 120 nm and a refractive index of 1.70 or greater with respect to light with a wavelength of 450 nm to 750 nm.

[0044] 9) The organic EL device according to 7), wherein the covering layer is a stacked layer or a mixed layer composed of two or more compounds, and the covering layer contains at least one phenanthroline compound represented by the general formula (A).

[0045] 9′) The organic EL device according to 7), wherein the cover layer contains two or more compounds, at least one of which is a phenanthroline compound represented by the general formula (A).

[0046] The covering layer may be a mixed layer containing two or more compounds or may have a laminated structure. Each layer constituting the laminated structure may be a single layer composed of one compound or a mixed layer containing two or more compounds.

[0047] 10) An electronic device or electronic component comprising a pair of electrodes and at least one organic layer sandwiched therebetween, wherein the organic layer contains the phenanthroline compound represented by the general formula (A) described in 1).

[0048] Effects of the Invention

[0049] The phenanthroline compound of the present invention has a high refractive index and a low extinction coefficient for light with a wavelength of 450 nm to 750 nm. Therefore, by using the phenanthroline compound of the present invention as a material for a cover layer, an organic EL device with improved efficiency can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a diagram showing an example of the structure of the organic EL element of the present invention. DETAILED DESCRIPTION

[0051] The following describes the content of the present application in detail. The following description of the components is based on representative embodiments and specific examples of the present application, but the present application is not limited to these embodiments and specific examples. In addition, in the present specification, "to" is a term indicating a range, for example, "5 to 10" indicates "5 or more and 10 or less", indicating a range including the values before and after "to" as lower limit values and upper limit values, and the numerical range indicated using "~" indicates a range including the values before and after "~" as lower limit values and upper limit values. Also, the description "hydrogen atom" indicates "H (ordinary hydrogen atom)", the description "heavy hydrogen atom" indicates "H (deuterium D)", and the description "halogen atom" indicates "F, Cl, Br, or I". 1 H (deuterium D)". 2 H (deuterium D)".

[0052] In the present specification, "transparent" means that the transmittance of visible light is 50% or more, for example, 80% or more, for example, 90% or more, for example, 99% or more. The transmittance of visible light can be measured by an ultraviolet / visible light spectrophotometer.

[0053] <Phenanthroline compound represented by General Formula (A)>

[0054] The phenanthroline compound of the present application has a structure represented by General Formula (A) below.

[0055] [Chemical Formula 3]

[0056]

[0057] In General Formula (A), Ar represents an unsubstituted heteroaryl group. The "heteroaryl group" of the "unsubstituted heteroaryl group" represented by Ar can be a monocyclic heteroaryl group, or a fused ring composed of two or more rings fused together. Here, the plurality of constituent rings constituting the fused ring of the heteroaryl group can all be heterocyclic rings, or can include a heterocyclic ring and a hydrocarbon ring (for example, a benzene ring). The heterocyclic ring and the hydrocarbon ring constituting the ring can be an aromatic ring, or an aliphatic ring, but is an aromatic heterocyclic ring in the fused ring as a whole. As the heteroatom contained in the heteroaryl group, a nitrogen atom, a sulfur atom, and an oxygen atom can be listed. The heteroatom contained in the heteroaryl group can be one or two or more. When the heteroaryl group contains two or more heteroatoms, the heteroatoms can be the same or different. The number of atoms constituting the ring skeleton of the heteroaryl group is, for example, 4 to 40, or 5 to 20, or 5 to 16, or 6 to 14. The number of carbon atoms of the heteroaryl group is, for example, 3 to 35, or 3 to 30, or 2 to 20. As the "heteroaryl group", specifically, a group selected from pyridyl, pyrimidinyl, triazinyl, furanyl, pyrrolyl, thienyl, quinolinyl, isoquinolinyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, benzoxazolyl, benzothiazolyl, oxazolopyridinyl, quinoxalinyl, quinazolinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, naphthridinyl, phenanthrolinyl, acridinyl, and carbazolinyl groups having 2 to 20 carbon atoms can be listed.

[0058] Ar is preferably an unsubstituted 2-benzoxazolyl group, an unsubstituted 2-benzothiazolyl group, an unsubstituted 2-oxazolopyridinyl group, an unsubstituted 2-benzofuranyl group, an unsubstituted 2-benzothienyl group, and more preferably an unsubstituted 2-benzothiazolyl group or an unsubstituted 2-oxazolopyridinyl group.

[0059] In General Formula (A), L1and L2independently represent a single bond, an arylene group, or a heteroarylene group. L1and L2may be the same as or different from each other.

[0060] The "arylene group" in L1and L2may be a monocyclic arylene group, or a fused ring composed of two or more rings fused together, or a linked ring composed of two or more rings linked by a single bond. Here, each of the constituent rings constituting the fused ring of the arylene group can be an aromatic hydrocarbon ring (for example, a benzene ring), or an aliphatic hydrocarbon ring, but is an aromatic hydrocarbon ring in the fused ring as a whole. The number of carbon atoms of the arylene group is, for example, 6 to 40, or 6 to 30, or 6 to 20, or 6 to 14. As the "arylene group", specifically, a group selected from phenylene, biphenyldiyl, terphenyldiyl, naphthalenediyl, anthracenediyl, phenanthrenediyl, fluorenediyl, spirobifluorenediyl, indenediyl, pyrenediyl, perylenediyl, fluoranthenediyl, triphenylenediyl groups having 6 to 30 carbon atoms can be listed.

[0061] As to the "heteroarylene group" in L1and L2, the description of the "heteroaryl group" in the above-mentioned description of the "heteroaryl group" in Ar can be referred to by substituting "heteroaryl group" for "heteroaryl group" in the description. As a specific example of the "heteroaryl group", a divalent group obtained by removing one hydrogen atom from the specific groups exemplified as the "heteroaryl group" in Ar can be exemplified.

[0062] L1and L2are each independently preferably a single bond or an arylene group, and at least one of L1and L2is preferably a single bond. The arylene group is preferably a phenylene group, and more preferably a 1,4-phenylene group.

[0063] The arylene group and the heteroarylene group in L1and L2may be unsubstituted, and at least one hydrogen atom of the arylene group and the heteroarylene group can be substituted with an atom or a group (sometimes, the "group" here is referred to as a "substituent") selected from the group consisting of a heavy hydrogen atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkyloxy group, an aryl group, and a heteroaryl group. As examples of the halogen atom, the silicon group, the alkyl group, the alkoxy group, the alkenyl group, the aryloxy group, the arylalkyloxy group, the aryl group, and the heteroaryl group, the following can be exemplified, respectively.

[0064] That is, a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like;

[0065] a silicon group such as a trimethylsilyl group, a triphenylsilyl group, and the like;

[0066] an alkyl group of a linear or branched chain having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, and the like;

[0067] an alkoxy group of a linear or branched chain having 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and the like;

[0068] an alkenyl group such as a vinyl group, an allyl group, and the like;

[0069] an aryloxy group such as a phenoxy group, a tolyloxy group, and the like;

[0070] an arylalkyloxy group such as a benzyloxy group, a phenethyloxy group, and the like;

[0071] an aryl group as an aromatic hydrocarbon group or a fused polycyclic aromatic group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a fluorenyl group, a spirobifluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, a fluoranthenyl group, a triphenylenyl group, and the like;

[0072] a heteroaryl group such as a pyridyl group, a thienyl group, a furanyl group, a pyrrolyl group, a quinolyl group, an isoquinolyl group, a benzofuranyl group, a benzothienyl group, an indolyl group, a carbazolyl group, a benzoxazolyl group, a benzothiazolyl group, a quinoxalyl group, a quinazolyl group, a benzimidazolyl group, a pyrazolyl group, a dibenzofuranyl group, a dibenzothienyl group, a carbolinyl group, and the like,

[0073] In addition, as examples of the substituent, an aryl group having 6 to 30 carbon atoms or a heteroaryl group having 2 to 20 carbon atoms can be exemplified. Furthermore, these substituents can be further substituted with an atom or a group selected from the group consisting of a heavy hydrogen atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkyloxy group, an aryl group, and a heteroaryl group.

[0074] Furthermore, when these substituents are substituents of a benzene ring (a benzene ring constituting a ring skeleton), the substituents can be bonded to each other or a plurality of substituents substituted on the same benzene ring can be bonded to each other via a single bond, a substituted or unsubstituted methylene group, an oxygen atom, or a sulfur atom to form a ring. As examples of the substituents of the methylene group, the description of the substituents of the methylene group represented by X described below can be referred to.

[0075] In General Formula (A), X represents a methylene group, an oxygen atom, or a sulfur atom, and at least one hydrogen atom of the methylene group can be substituted with an atom or a group selected from the group consisting of a heavy hydrogen atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkyloxy group, an aryl group, and a heteroaryl group. As for the description and specific examples of the halogen atom, the silicon group, the alkyl group, the alkoxy group, the alkenyl group, the aryloxy group, the arylalkyloxy group, the aryl group, and the heteroaryl group, the description of the substituents in L1and L2described above can be referred to.

[0076] X is preferably a substituted or unsubstituted methylene group, and more preferably a dimethylmethylene group or an unsubstituted methylene group.

[0077] In General Formula (A), A represents an unsubstituted phenanthroline group. The phenanthroline group is a 1-valent group obtained by removing one hydrogen atom from a heterocycle (phenanthroline ring) obtained by substituting two methyl groups (=CH-) constituting a phenanthrene ring with nitrogen atoms. The position of the nitrogen atom of the phenanthroline group is not particularly limited, but is preferably the 1-position and the 10-position. That is, A of General Formula (A) is preferably a 1,10-phenanthroline group, and more preferably a 1,10-phenanthroline-2-yl group.

[0078] In the phenanthroline compound represented by General Formula (A), Ar-L1- and Ar-L2- can be bonded at any position of the benzene ring (benzene ring constituting a ring skeleton) to which the bonding bond is attached. In a preferred mode of the present application, the phenanthroline compound represented by General Formula (A) has a structure represented by General Formula (B) described below.

[0079] [Chemical Formula 4]

[0080]

[0081] The meanings of A, Ar, L1, L2, and X of General Formula (B) are the same as those of A, Ar, L1, L2, and X of General Formula (A). For the description of A, Ar, L1, L2, and X of General Formula (B), reference can be made to the corresponding description of General Formula (A).

[0082] Hereinafter, preferred specific examples of the compound represented by General Formula (A) will be illustrated. However, the compound represented by General Formula (A) that can be used in the present application should not be interpreted limitatively by these specific examples.

[0083] [Chemical Formula 5]

[0084]

[0085] [Chemical Formula 6]

[0086]

[0087] [Chemical Formula 7]

[0088]

[0089] <Method for synthesizing the compound represented by General Formula (A)>

[0090] The phenanthroline compound represented by General Formula (A) is a novel compound. The compound represented by General Formula (A) can be synthesized, for example, using a coupling reaction caused by a publicly known palladium catalyst or the like (for example, refer to Non-Patent Literature 4).

[0091] The purification method of the phenanthroline compound represented by General Formula (A) is not particularly limited, and can be performed by a publicly known method for purifying organic compounds, such as purification by column chromatography, adsorption purification using silica gel, activated carbon, activated clay, or the like, recrystallization purification or crystallization purification using a solvent, sublimation purification, and the like. The identification of the compound can be performed by NMR analysis. As the physical property values of the phenanthroline compound, the measurement of the melting point, the glass transition temperature (Tg), the refractive index, and the extinction coefficient is preferably performed. The melting point is an index of the evaporation property, the glass transition temperature (Tg) is an index of the stability in a thin film state, and the refractive index and the extinction coefficient are indices related to the improvement of the light extraction efficiency.

[0092] The melting point and the glass transition temperature (Tg) can be measured using a powder by a high-sensitivity differential scanning calorimeter (manufactured by Bruker AXS, DSC3100SA).

[0093] The refractive index and the extinction coefficient can be measured using a spectrophotometer (manufactured by Filmetrics, F10-RT-UV) by forming a thin film of 80 nm on a silicon substrate.

[0094] The phenanthroline compound represented by General Formula (A) of the present application has a high refractive index in the range of 450 nm to 750 nm and a low extinction coefficient. Also, the phenanthroline compound represented by General Formula (A) of the present application is (3) capable of being deposited, (4) has a high glass transition temperature and is stable in a thin film state, and (5) has high heat resistance. Therefore, the phenanthroline compound represented by General Formula (A) is useful as a material for a cover layer of an organic EL element. That is, by providing a cover layer containing the phenanthroline compound represented by General Formula (A) on the outside of a transparent or semi-transparent electrode of an organic EL element, an organic EL element having a significantly improved light extraction efficiency, high luminous efficiency, and a long lifetime can be realized.

[0095] Herein, the "cover layer" in the present specification means a layer disposed on the side (outside) opposite to the light-emitting layer of at least one of the pair of electrodes in an organic EL element in which a light-emitting layer is disposed between a pair of electrodes. The cover layer containing the compound represented by General Formula (A) can be disposed on the outside of only one of the pair of electrodes, or can be disposed on the outside of both electrodes. In addition, an organic layer such as a charge transport layer can be disposed between the light-emitting layer and each electrode of the organic EL element to which the cover layer is applied.

[0096]

[0097] Next, an organic electroluminescent element (organic EL element) of the present application will be described. The organic EL element of the present application has at least an anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode electrode, and a cover layer in this order, and is characterized in that the cover layer contains a phenanthroline compound represented by General Formula (A).

[0098] The description of the phenanthroline compound represented by General Formula (A) can be referred to the description of the "phenanthroline compound represented by General Formula (A)" described above.

[0099] ​As a structure of the organic EL element, for example, in the case of a light-emitting element of a top emission structure, a structure in which an anode, a hole-transporting layer, a light-emitting layer, an electron-transporting layer, a cathode, and a cover layer are sequentially formed over a substrate made of glass or the like can be given. Further, a structure having a hole-injection layer between the anode and the hole-transporting layer, a structure having an electron-blocking layer between the hole-transporting layer and the light-emitting layer, a structure having a hole-blocking layer between the light-emitting layer and the electron-transporting layer, and a structure having an electron-injection layer between the electron-transporting layer and the cathode can be given. In these multilayer structures, one organic layer can have multiple functions, for example, a structure functioning as both a hole-injection layer and a hole-transporting layer, a structure functioning as both a hole-transporting layer and an electron-blocking layer, a structure functioning as both a hole-blocking layer and an electron-transporting layer, a structure functioning as both an electron-transporting layer and an electron-injection layer, or the like. Further, a structure in which two or more organic layers having the same function are stacked, a structure in which two hole-transporting layers are stacked, a structure in which two light-emitting layers are stacked, a structure in which two electron-transporting layers are stacked, a structure in which two cover layers are stacked, or the like can be given.

[0100] The total thickness of each layer of the organic EL element is preferably 200 nm to 750 nm, more preferably 350 nm to 600 nm. Further, the thickness of the cover layer is preferably, for example, 30 nm to 120 nm, more preferably 40 nm to 80 nm. In this case, a good light extraction efficiency can be obtained. Note that the thickness of the cover layer can be changed as appropriate in accordance with the kind of light-emitting material used for the light-emitting element, the thickness of the organic EL element excluding the cover layer, or the like.

[0101] Next, each component and each layer included in the organic EL element will be described.

[0102] [Anode electrode]

[0103] As a material of the anode of the organic EL element, an electrode material having a large work function such as ITO (Indium Tin Oxide) and gold is used.

[0104] [Hole-injection layer]

[0105] As a material for the hole injection layer of the organic EL element, an aromatic amine compound having a structure in which three or more triphenylamine structures are linked by single bonds or two-valent groups not containing hetero atoms can be exemplified. As the aromatic amine compound, for example, a starburst-type triphenylamine derivative, various triphenylamine tetramers, and the like can be exemplified. Further, as a material for the hole injection layer, a phthalocyanine compound typified by copper phthalocyanine, an acceptor heterocyclic compound such as hexacyanotriazatriphenylene, and a coating-type high molecular material can be used. The hole injection layer can be composed of a single layer formed by individually depositing one of these hole injection materials, or can be composed of a mixed layer formed by depositing two or more kinds of materials in mixture. Further, the hole injection layer can have a single layer structure, or can have a stacked structure in which layers individually deposited or layers deposited in mixture are stacked. These materials can be formed into thin films by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0106] [hole transport layer]

[0107] As a material for the hole transport layer of the organic EL element, a diphenylamine derivative such as N,N'-diphenyl-N,N'-di(m-methylphenyl)benzidine (hereinafter, referred to as TPD), N,N'-diphenyl-N,N'-di(a-naphthyl)benzidine, and N,N,N',N'-tetraphenylbenzidine, and 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane, or the like can be used. In particular, it is preferable to use an aromatic amine compound having a structure in which two triphenylamine structures are linked by single bonds or two-valent groups not containing hetero atoms in the molecule, and for example, it is preferable to use N,N,N',N'-tetraphenylbenzidine or the like. Further, it is preferable to use an aromatic amine compound having a structure in which three or more triphenylamine structures are linked by single bonds or two-valent groups not containing hetero atoms in the molecule, and for example, it is preferable to use various triphenylamine trimers and tetramers, or the like. The hole transport layer can be composed of a single layer formed by individually depositing one of these hole transport materials, or can be composed of a mixed layer formed by depositing two or more kinds of materials in mixture. Further, the hole transport layer can have a single layer structure, or can have a stacked structure in which layers individually deposited or layers deposited in mixture are stacked. Further, as the hole injection / transport layer, a coating-type high molecular material such as poly(3,4-ethylenedioxythiophene) / poly(styrenesulfonate) or the like can be used. These materials can be formed into thin films by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0108] Further, as a material of the hole injection layer and the hole transport layer, a substance in which a p-type dopant such as tribromoaniline hexachloroantimony or an axiylene derivative (see Patent Document 3, for example) is doped into a material generally used in these layers, a high molecular compound having a structure containing a diphenylamine derivative such as TPD as a partial structure, and the like can be used.

[0109] [Electron-Blocking Layer]

[0110] The organic EL element of the present application can have an electron-blocking layer between the light-emitting layer and the hole transport layer. As a material of the electron-blocking layer, 4,4',4"-tris(N-carbazolyl)triphenylamine (hereinafter, referred to as TCTA), 9,9-bis[4-(9H-carbazol-9-yl)phenyl]fluorene, 1,3-bis(9H-carbazol-9-yl)benzene (hereinafter, referred to as mCP), and a carbazole derivative such as 2,2-bis(4-carbazol-9-yl-phenyl)adamantane, and a compound having a triphenylsilyl group and a triarylamine structure represented by 9-[4-(9H-carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene, and the like having an electron-blocking function can be used. The electron-blocking layer can be composed of a single layer in which one of these electron-blocking materials is deposited alone, or can be composed of a mixed layer in which two or more kinds of materials are deposited in mixture. Further, the electron-blocking layer can be a single layer structure, or can be a stacked structure in which layers deposited alone are stacked with each other or layers deposited in mixture are stacked with each other, or a stacked structure in which layers deposited alone and layers deposited in mixture are stacked. These materials can be formed into a thin film by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0111] [Light-Emitting Layer]

[0112] As the material of the light-emitting layer of the organic EL element, metal complexes of quinolinol derivatives such as tris(8-hydroxyquinoline)aluminum (Alq3), various metal complexes, anthracene derivatives, bis(styrylbenzene) derivatives, pyrene derivatives, oxazole derivatives and poly(p-phenylene vinylene) derivatives can be used. In addition, the light-emitting layer can be composed of a host material and a dopant material. As the host material, anthracene derivatives can be preferably used. In addition, the above-mentioned light-emitting materials, heterocyclic compounds having an indole ring as a partial structure of a condensed ring, heterocyclic compounds having a carbazole ring as a partial structure of a condensed ring, carbazole derivatives, thiazole derivatives, benzimidazole derivatives and polydialkylfluorene derivatives can also be used. In addition, as the dopant material, quinacridone, coumarin, rubrene, perylene and their derivatives, benzopyran derivatives, rhodamine derivatives and aminostyrene derivatives can be used, and green light-emitting materials are particularly preferably used. The light-emitting layer may be composed of a single layer formed by forming a single film of one of the above-mentioned light-emitting materials, or a mixed layer formed by forming a film of a mixture of two or more materials (for example, two or more light-emitting materials or one or more host materials and one or more dopant materials). Furthermore, the light-emitting layer may have a single-layer structure, a stacked structure formed by stacking single-layer films or mixed-layer films, or a stacked structure formed by stacking single-layer films and mixed-layer films.

[0113] Furthermore, as a luminescent material, a phosphorescent light emitting body can also be used. As a phosphorescent light emitting body, a phosphorescent light emitting body of a metal complex of iridium and platinum can be used. For example, a green phosphorescent light emitting body such as Ir(ppy)3(tris(2-phenylpyridine)iridium(III)), a blue phosphorescent light emitting body such as FIrpic(bis[2-(4,6-difluorophenyl)pyridine-C2,N](pyridinecarbonyl)iridium(III)), a red phosphorescent light emitting body such as FIr6(bis(2,4-difluorophenylpyridine)tetrakis(1-pyrazolyl)borateiridium(III)), a red phosphorescent light emitting body such as Btp2Ir(acac)(bis(2-benzo[b]thiophene-2-yl-pyridine)(acetylacetone)iridium(III)) can be used, and a green phosphorescent light emitting body is particularly preferably used. The light emitting layer can be composed of only these phosphorescent light emitting bodies, or it can be composed of a host material and a phosphorescent light emitting body (for example, a co-evaporated film of a host material and a phosphorescent light emitting body). As a host material for hole injection / transport, 4,4'-di(N-carbazolyl)biphenyl or carbazole derivatives such as TCTA and mCP can be used. As a host material for electron transport, p-bis(triphenylsilyl)benzene and 2,2',2"-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) can be used.

[0114] In order to avoid concentration quenching, the doping amount of the phosphorescent emitter to the host material is preferably in the range of 1 to 30 wt % relative to the total weight of the light-emitting layer.

[0115] Further, as the light-emitting material, a material emitting delayed fluorescence such as a carbazole dicyanobenzene (CDCB) derivative such as PIC-TRZ, CC2TA, PXZ-TRZ, 4CzIPN, or the like can be used (for example, refer to Non-Patent Document 5). These materials can be formed into a thin film by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0116] [Chemical Formula 8]

[0117]

[0118] [Hole-blocking layer]

[0119] The organic EL element of the present application can have a hole-blocking layer between the light-emitting layer and the electron-transporting layer. As the material of the hole-blocking layer, a phenanthroline derivative such as bathocuproin, a metal complex of a quinolinol derivative such as bis(2-methyl-8-quinolinato)-4-phenylphenol aluminum (III) (hereinafter, referred to as BAIq), various rare earth complexes, a triazole derivative, a triazine derivative, a pyrimidine derivative, an oxadiazole derivative, a benzoxazole derivative, and the like having a hole-blocking function can be used. These materials can also be used as the material of the electron-transporting layer. The hole-blocking layer can be composed of a single layer formed of one of these hole-blocking materials alone, or can be composed of a mixed layer formed by mixing two or more materials. Further, the hole-blocking layer can be a single layer structure, or can be a stacked structure in which layers formed of one of these hole-blocking materials alone are stacked with each other, or layers formed by mixing two or more materials are stacked with each other, or a stacked structure in which layers formed of one of these hole-blocking materials alone and layers formed by mixing two or more materials are stacked. These materials can be formed into a thin film by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0120] [Electron-transporting layer]

[0121] As the material of the electron-transporting layer of the organic EL element, a metal complex of a quinolinol derivative such as AIq3 and BAIq, various metal complexes, a triazole derivative, a triazine derivative, a pyrimidine derivative, an oxadiazole derivative, a pyridine derivative, a benzimidazole derivative, a benzoxazole derivative, a thiadiazole derivative, an anthracene derivative, a carbodiimide derivative, a quinoxaline derivative, a pyridine indole derivative, a phenanthroline derivative, a thioxyl derivative, and the like can be used. The electron-transporting layer can be composed of a single layer formed of one of these electron-transporting materials alone, or can be composed of a mixed layer formed by mixing two or more materials. Further, the electron-transporting layer can be a single layer structure, or can be a stacked structure in which layers formed of one of these electron-transporting materials alone are stacked with each other, or layers formed by mixing two or more materials are stacked with each other, or a stacked structure in which layers formed of one of these electron-transporting materials alone and layers formed by mixing two or more materials are stacked. These materials can be formed into a thin film by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0122] [Electron-injecting layer]

[0123] As a material of the electron injection layer of the organic EL element, an alkali metal salt such as lithium fluoride and cesium fluoride, an alkaline earth metal salt such as magnesium fluoride, a metal complex of a quinolinol derivative such as lithium quinolinol, a metal oxide such as aluminum oxide, and a metal such as ytterbium (Yb), samarium (Sm), calcium (Ca), strontium (Sr), and cesium (Cs) can be used. By appropriately selecting the electron transport layer and the cathode, the electron injection layer can be omitted.

[0124] Further, as a material of the electron injection layer and the electron transport layer, a material obtained by doping a material usually used in these layers with an n-type metal dopant such as cesium can be used.

[0125] [Cathode electrode]

[0126] As a material of the cathode of the organic EL element, a metal having a low work function such as aluminum, an alloy having a lower work function such as a magnesium-silver alloy, a magnesium-calcium alloy, a magnesium-indium alloy, and an aluminum-magnesium alloy, and a conductive transparent material such as ITO (Indium Tin Oxide) and IZO (Indium Zinc Oxide) can be used. By forming the metal and the alloy in a thin thickness of about 10 to 200 nm, a semi-transparent cathode electrode is constituted.

[0127] [Covering layer]

[0128] The organic EL element of the present application contains a phenanthroline compound represented by General Formula (A) in the covering layer. The covering layer can be constituted by a single layer formed by depositing a single phenanthroline compound selected from the group of compounds represented by General Formula (A), or can be constituted by a mixed layer formed by depositing a mixture of two or more phenanthroline compounds selected from the group of compounds, or can be constituted by a mixed layer formed by depositing a mixture of a phenanthroline compound selected from the group of compounds and a material other than the phenanthroline compound represented by General Formula (A). Further, the covering layer can be a single layer structure, or can be a laminated structure in which the layers deposited singly or the layers deposited as a mixture are laminated, or can be a laminated structure in which the layers deposited singly and the layers deposited as a mixture are laminated. These materials can be formed into a thin film by a publicly known method such as an evaporation method, a spin coating method, and an inkjet method.

[0129] In the organic EL element, the thickness of the covering layer is preferably in the range of 30 nm to 120 nm, and particularly preferably in the range of 40 nm to 80 nm.

[0130] Further, the refractive index of the covering layer containing the phenanthroline compound represented by General Formula (A) with respect to light having a wavelength of 450 nm to 700 nm is preferably 1.70 or more, and particularly preferably 1.85 or more.

[0131] The above describes the present application using an organic EL element of a top emission structure as an example, but the organic EL element to which the present application is applied is not limited to this, and can also be an organic EL element of a bottom emission structure or an organic EL element of a dual emission structure that emits light from both the top and bottom. The description of each part and each layer of the organic EL element constituting the bottom emission structure and the dual emission structure can be referred to the description of the above organic EL element. Among them, the electrode present in the direction of extracting light from the light emitting element to the outside is preferably transparent or semi-transparent. That is, in the bottom emission structure, the electrode on the substrate side is preferably transparent or semi-transparent, and in the dual emission structure, the electrodes on both sides are preferably transparent or semi-transparent.

[0132] <Electronic device and electronic element>

[0133] The electronic device and electronic element of the present application have a pair of electrodes and at least one organic layer disposed between the pair of electrodes, and contain a compound represented by General Formula (I) in at least one of the organic layers. The description of the compound represented by General Formula (I) can be referred to the description of the above <Compound represented by General Formula (I)> column.

[0134] As the electronic device, a display device or a light emitting device provided with an organic EL element can be exemplified, and in addition thereto, an electrophotographic photoreceptor, an image sensor, a photoelectric conversion element, a solar cell, and the like can be exemplified. As the display device, for example, a display part of an organic EL panel module or the like, a television, a mobile phone, a tablet, a personal computer, and the like can be exemplified. As the light emitting device, for example, illumination or a vehicle lamp, and the like can be exemplified.

[0135] Example

[0136] Hereinafter, the embodiments of the present application will be specifically described by examples, but the present application is not limited to the following examples as long as the gist thereof is not exceeded.

[0137] [Example 1]

[0138] <Synthesis of 2-(4-(9,9-dimethyl-7-(1,10-phenanthroline-2-yl)-9H-fluoren-2-yl)phenyl)dibenzothiophene (Compound 30)>

[0139] A reaction vessel was charged with 2-bromo-1, 10-phenanthroline: 5.0 g, 2-(4-(9,9-dimethyl-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-fluoren-2-yl)phenyl)benzothiazole: 11.2 g, tetrakis(triphenylphosphine)palladium(0): 0.5 g, potassium carbonate: 5.3 g, and stirred at reflux in a mixture solvent of toluene / EtOH / H2O overnight. After cooling, MeOH was added, and the precipitated solid was filtered to obtain a crude product. The obtained crude product was purified by crystallization in a mixed solvent of monochlorobenzene / acetone to obtain white powder of 2-(4-(9,9-dimethyl-7-(1,10-phenanthrolin-2-yl)-9H-fluoren-2-yl)phenyl)dibenzothiazole (Compound 30): 12.3 g (yield: 70.7%).

[0140] [Chemical Formula 9]

[0141]

[0142] The structure of the obtained white powder was identified using NMR.

[0143] The structure of the obtained white powder was identified using NMR. 1 The signals of the following 27 hydrogens were detected by1-H-NMR (CDCI3), and confirmed to be Compound 30.

[0144] δ (ppm) = 9.27 (1H), 8.42 (1H), 8.34 (2H), 8.29 (1H), 8.26 (3H), 8.11 (1H), 7.94 (2H), 7.90 (1H), 7.83 (4H), 7.76 (1H), 7.69 (1H), 7.67 (1H), 7.52 (1H), 7.41 (1H), 1.69 (6H).

[0145] [Example 2]

[0146] < Synthesis of 2-(4-(9,9-dimethyl-7-(1,10-phenanthrolin-2-yl)-9H-fluoren-2-yl)phenyl)oxazolo[5,4-b]pyridine (Compound 31) >

[0147] A reaction vessel was charged with 2-bromo-l,10-phenanthroline: 3.0 g, 2-(4-(9,9-dimethyl-7-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)-9H-fluoren-2-yl)phenyl)oxazolo[5,4-b]pyridine: 6.6 g, tetrakis(triphenylphosphine)palladium(0): 0.3 g, potassium carbonate: 3.2 g, and stirred under reflux in a mixture solvent of toluene / EtOH / H2O overnight. After cooling, MeOH was added, and the precipitated solid was filtered to obtain a crude product. The obtained crude product was purified by crystallization in a mixed solvent of monochlorobenzene / acetone to obtain white powder of 2-(4-(9,9-dimethyl-7-(l,10-phenanthrolin-2-yl)-9H-fluoren-2-yl)phenyl)oxazolo[5,4-b]pyridine (Compound 31): 3.2 g (yield: 48.5%).

[0148] [Chemical Formula 10]

[0149]

[0150] The structure of the obtained white powder was identified using NMR.

[0151] The structure of the obtained white powder was identified using NMR. 1 H-NMR (CDCI3) detected signals of the following 26 hydrogens, confirming Compound 31.

[0152] δ (ppm) = 9.26 (1H), 8.44 (1H), 8.40 (2H), 8.37 (1H), 8.34 (1H), 8.33 (1H), 8.28 (1H), 8.18 (1H), 8.09 (1H), 7.93 (1H), 7.91 (1H), 7.88 (2H), 7.82 (2H), 7.78 (1H), 7.70 (1H), 7.67 (1H), 7.38 (1H), 1.70 (6H).

[0153] [Example 3]

[0154] < Synthesis of 2-(7-(4-(l,10-phenanthrolin-2-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)benzoxazole (Compound 38) >

[0155] A reaction vessel was charged with 2-chlorobenzoxazole: 2.5 g, 2-(4-(9,9-dimethyl-7-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)-9H-fluoren-2-yl)phenyl)-l,10-phenanthroline: 10.3 g, tetrakis(triphenylphosphine)palladium(0): 0.4 g, potassium carbonate: 4.5 g, and stirred at reflux in a mixture solvent of toluene / EtOH / H2O overnight. After cooling, MeOH was added, and the precipitated solid was filtered to obtain a crude product. The obtained crude product was purified by crystallization in a mixed solvent of monochlorobenzene / acetone to obtain white powder of 2-(7-(4-(l,10-phenanthrolin-2-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)benzoxazole (Compound 38): 5.7 g (yield: 61.9%).

[0156] [Chemical Formula 11]

[0157]

[0158] The structure of the obtained white powder was identified using NMR.

[0159] The structure of the obtained white powder was identified using NMR. 1 H-NMR (CDCI3) detected signals of the following 27 hydrogens, confirming Compound 38.

[0160] δ (ppm) = 9.27 (1H), 8.49 (2H), 8.39 (1H), 8.33 (1H), 8.28 (2H), 8.18 (1H), 7.89 (3H), 7.87 (1H), 7.81 (4H), 7.73 (1H), 7.66 (1H), 7.62 (1H), 7.37 (2H), 1.66 (6H).

[0161] [Example 4]

[0162] < Synthesis of 2-(7-(4-(l,10-phenanthrolin-2-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)benzothiazole (Compound 39) >

[0163] A reaction vessel was charged with 2-(4-bromophenyl)-l,10-phenanthroline: 10.0 g, 2-(9,9-dimethyl-7-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)-9H-fluoren-2-yl)benzothiazole: 14.9 g, tetrakis(triphenylphosphine)palladium(0): 0.7 g, potassium carbonate: 8.3 g, and stirred under reflux in a mixed solvent of toluene / EtOH / H2O overnight. After cooling, MeOH was added, and the precipitated solid was filtered to obtain a crude product. The obtained crude product was purified by crystallization in a mixed solvent of toluene / acetone to obtain white powder of 2-(7-(4-(l,10-phenanthrolin-2-yl)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)benzothiazole (Compound 39): 12.3 g (yield: 70.7%).

[0164] [Chemical Formula 12]

[0165]

[0166] The structure of the obtained white powder was identified using NMR.

[0167] The structure of the obtained white powder was identified using NMR. 1 H-NMR (CDC13) detected signals of the following 27 hydrogens, confirming Compound 39.

[0168] δ (ppm) = 9.28 (1H), 8.49 (2H), 8.33 (1H), 8.28 (1H), 8.26 (1H), 8.18 (1H), 8.11 (1H), 8.07 (1H), 7.93 (1H), 7.89-7.77 (7H), 7.73 (1H), 7.66 (1H), 7.52 (1H), 7.40 (1H), 1.67 (6H).

[0169] [Example 5]

[0170] Using the compounds obtained in Examples 1 to 4, the melting point and glass transition temperature (Tg) were measured by a high sensitivity differential scanning calorimeter (Brüker AXS, DSC3100SA). The measurement results are shown in Table 1.

[0171] [Table 1]

[0172] melting point glass transition temperature compound (30) 303.1 129.9 compound (31) 266.9 139.0 compound (38) 324.1 136.4 compound (39) 322.0 128.4

[0173] From the results shown in Table 1, it was found that the compounds obtained in Examples 1 to 4 have high melting points, and have glass transition temperatures of 100°C or higher. This result indicates that the thin film state is stable.

[0174] [Example 6]

[0175] Using the compounds obtained in Examples 1 to 4, an evaporation film having a film thickness of 80 nm was formed on a silicon substrate, and using a spectroscopic measurement device (F10-RT-UV, manufactured by Filmetrics, Inc.), the refractive index n and the attenuation coefficient k at a wavelength of 450 nm and 750 nm were measured. Also, for comparison, Alq3 and a comparative compound (CPL-1) of the following structural formula were measured (for example, refer to Patent Document 4). The measurement results are shown in Table 2.

[0176] [Chemical Formula 13]

[0177]

[0178] [Table 2]

[0179]

[0180] As shown in Table 2, the phenanthroline compound of the present application has a high refractive index compared to Alq3 and the comparative compound (CPL-1) between a wavelength of 450 nm and 750 nm. This result indicates that by using the phenanthroline compound of the present application as a constituent material of a cover layer, it is possible to expect an improvement in light extraction efficiency in an organic EL element.

[0181] [Example 7]

[0182] As shown in Table 2, the phenanthroline compound of the present application has a high refractive index compared to Alq3 and the comparative compound (CPL-1) between a wavelength of 450 nm and 750 nm. This result indicates that by using the phenanthroline compound of the present application as a constituent material of a cover layer, it is possible to expect an improvement in light extraction efficiency in an organic EL element. Figure 1 An organic EL element was produced by forming a reflective ITO electrode as a transparent anode 2 on a glass substrate 1, and sequentially evaporating a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, a cathode 8, and a cover layer 9 thereon.

[0183] Specifically, after performing 20 minutes of ultrasonic cleaning of the glass substrate 1 on which ITO having a film thickness of 50 nm, a reflective film of silver alloy having a film thickness of 100 nm, and ITO having a film thickness of 5 nm were sequentially formed in isopropyl alcohol, drying was performed on a hot plate heated to 250°C for 10 minutes. Then, after performing 2 minutes of UV ozone treatment, the glass substrate with ITO was installed in a vacuum evaporation machine, and reduced to a pressure of 0.001 Pa or less. Next, as the hole injection layer 3, a binary evaporation of an electron acceptor (Acceptor-1) of the following structural formula and a compound (HTM-1) of the following structural formula was performed at an evaporation rate ratio of Acceptor-1:compound (HTM-1) = 3:97 so as to cover the transparent anode 2, and formed to a film thickness of 10 nm.

[0184] On the above hole injection layer 3, as a hole transport layer 4, a compound of the following structural formula (HTM-1) was formed into a film thickness of 140 nm. On the hole transport layer 4, as a light-emitting layer 5, a compound of the following structural formula (EMD-1) and a compound of the following structural formula (EMH-1) were subjected to binary evaporation at an evaporation rate ratio of (EMD-1) : (EMH-1) = 5 : 95, and formed into a film thickness of 20 nm. On the light-emitting layer 5, as an electron transport layer 6, a compound of the following structural formula (ETM-1) and a compound of the following structural formula (ETM-2) were subjected to binary evaporation at an evaporation rate ratio of (ETM-1) : (ETM-2) = 50 : 50, and formed into a film thickness of 30 nm. On the electron transport layer 6, as an electron injection layer 7, lithium fluoride was formed into a film thickness of 1 nm. On the electron injection layer 7, as a cathode 8, a magnesium-silver alloy was formed into a film thickness of 12 nm.

[0185] Finally, as a cover layer 9, the compound (30) of Example 1 was formed into a film thickness of 60 nm. The organic EL element thus produced was subjected to property measurement in the atmosphere at normal temperature, and the measurement results of the light-emitting property under application of a direct current voltage were collectively shown in Table 3.

[0186] [Chemical Formula 14]

[0187]

[0188] [Examples 8 to 10]

[0189] In Example 7, the organic EL element was produced under the same conditions except that the compounds obtained in Examples 2 to 4 were used instead of the compound (30) of Example 1 as the cover layer 9. The organic EL element thus produced was subjected to property measurement in the atmosphere at normal temperature, and the measurement results of the light-emitting property under application of a direct current voltage were collectively shown in Table 3.

[0190] [Comparative Example 1]

[0191] For comparison, in Example 7, the organic EL element was produced under the same conditions except that Alq3was used instead of the compound (30) of Example 1 as the cover layer 9. The organic EL element thus produced was subjected to property measurement in the atmosphere at normal temperature, and the measurement results of the light-emitting property under application of a direct current voltage were collectively shown in Table 3.

[0192] [Comparative Example 2]

[0193] For comparison, in Example 7, an organic EL element was produced under the same conditions except that compound (CPL-1) was used instead of compound (30) of Example 1 as the cover layer 9. The produced organic EL element was subjected to property measurement in the atmosphere at ordinary temperature, and the results of measurement of the light emission property under application of a direct current voltage were collectively shown in Table 3.

[0194] The results obtained by measuring the element properties and element life of the organic EL elements produced in the examples and comparative examples are collectively shown in Table 3. The element life measured in the present application was measured as the time until the luminance decreased to 95% of the initial luminance when driven at a constant current of 10 mA / cm 2

[0195] [Table 3]

[0196]

[0197] As shown in Table 3, the elements of Comparative Examples 1 and 2, although having approximately the same driving voltage as the elements of Examples 7 to 10 at a current density of 10 mA / cm 2

[0198] Industrial Applicability

[0199] Since the phenanthroline compound of the present application has a high refractive index, can significantly improve the light extraction efficiency, and is stable in a thin film state, it is excellent as a compound suitable for use in an organic EL element. Furthermore, the organic EL element produced using the phenanthroline compound of the present application can achieve high efficiency. Furthermore, when it is intended to display an image that is clear and bright with good color purity, the use of the compound of the present application that does not have an absorption characteristic in each of the wavelength regions of blue, green, and red is particularly suitable. For example, development in household electric products or lighting applications can be expected.

[0200] Explanation of Symbols

[0201] 1 - glass substrate, 2 - transparent anode, 3 - hole injection layer, 4 - hole transport layer, 5 - light emitting layer, 6 - electron transport layer, 7 - electron injection layer, 8 - cathode, 9 - cover layer.​​

Claims

1. A phenanthroline compound represented by the following general formula (A), [Chemical Formula 1] In the formula, Ar represents an unsubstituted heteroaryl group, L1 and L2 represent a single bond, which may be the same as or different from each other, an arylene group, or a heteroarylene group, wherein at least one hydrogen atom of the arylene group or the heteroarylene group may be substituted by an atom or group selected from the group consisting of a deuterium atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkoxy group, an aryl group, and a heteroaryl group, X represents a methylene group, an oxygen atom or a sulfur atom, at least one hydrogen atom of the methylene group may be substituted by an atom or group selected from the group consisting of a deuterium atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkoxy group, an aryl group and a heteroaryl group, A represents an unsubstituted phenanthroline group.

2. The phenanthroline compound according to claim 1, wherein A in the general formula (A) is an unsubstituted 1,10-phenanthroline group.

3. The phenanthroline compound according to claim 2, wherein The general formula (A) is the following general formula (B), [Chemical Formula 2] In the formula, A represents an unsubstituted 1,10-phenanthroline group, and Ar, L1, L2 and X are as defined in the general formula (A).

4. The phenanthroline compound according to claim 3, wherein X in the general formula (B) is a methylene group, and at least one hydrogen atom of the methylene group may be substituted by an atom or group selected from the group consisting of a deuterium atom, a cyano group, a nitro group, a halogen atom, a silicon group, an alkyl group, an alkoxy group, an alkenyl group, an aryloxy group, an arylalkoxy group, an aryl group, and a heteroaryl group.

5. The phenanthroline compound according to claim 4, wherein L1 and L2 in the general formula (B) are a single bond or an unsubstituted 1,4-phenylene group.

6. The phenanthroline compound according to claim 5, wherein Ar in the general formula (B) is an unsubstituted quinolyl group, an unsubstituted isoquinolyl group, an unsubstituted benzoxazolyl group, an unsubstituted benzothiazolyl group, an unsubstituted oxazolopyridinyl group, an unsubstituted benzofuranyl group or an unsubstituted benzothiophenyl group.

7. An organic EL device comprising at least an anode electrode, a hole transport layer, a light emitting layer, an electron transport layer, a cathode electrode, and a covering layer in this order, wherein the covering layer contains the phenanthroline compound represented by the general formula (A) according to claim 1.

8. The organic EL element according to claim 7, wherein The deposited film of the phenanthroline compound represented by the general formula (A) is vacuum-deposited on a silicon substrate to a thickness of 80 nm and has a refractive index of 1.70 or higher in the wavelength range of 450 nm to 750 nm as measured at room temperature (25° C.).

9. The organic EL element according to claim 7, wherein The covering layer is a stacked layer or a mixed layer composed of two or more compounds, and the covering layer contains at least one phenanthroline compound represented by the general formula (A). 10 . An electronic device or electronic component comprising a pair of electrodes and at least one organic layer interposed therebetween, wherein the organic layer contains the phenanthroline compound represented by the general formula (A) according to claim 1 .

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