JP2014049696A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic-inorganic hybrid organic electroluminescent element superior in light-emitting characteristics to a conventional organic-inorganic hybrid organic electroluminescent element.SOLUTION: The organic electroluminescent element having a structure in which a plurality of layers are laminated is characterized in that: it has a first metal oxide layer, a low-molecular compound layer including a light-emitting layer, and a second metal oxide layer in this order between a first electrode and a second electrode; and the light-emitting layer contains at least one metal complex functioning as a host.

Description

The present invention relates to an organic electroluminescent device. More specifically, the present invention relates to an organic electroluminescent element that can be used as a display device such as a display unit of an electronic device, a lighting device, or the like.

Organic electroluminescent elements are thin, flexible and flexible, and when used as display devices, they have higher brightness and higher definition than current mainstream liquid crystal and plasma display devices. In addition, it has excellent features such as a wider viewing angle than liquid crystal display devices, so it is expected to expand its use as a display for TVs and mobile phones, and as a lighting device in the future. Element.
The organic electroluminescent element has a structure in which a plurality of layers such as an electron transport layer, a light emitting layer, and a hole transport layer are laminated between a cathode and an anode, and is a material suitable for constituting each layer. Research and development are being conducted. Among these, for the light emitting layer, it is known that the luminous efficiency is improved by using a phosphorescent material, and an organic electroluminescent element using the phosphorescent material has been researched and reported (for example, non-patented). Reference 1). When a phosphorescent material is used, the phosphorescent material is usually dispersed in a host material. For example, CBP which is an organic material or Bepp2 which is a metal complex is Ir (ppy) ₃ which is a phosphorescent material. An organic electroluminescent element using a material in which a light emitting layer is dispersed as a light emitting layer is disclosed (see Non-Patent Documents 2 and 3).

On the other hand, as such an organic electroluminescent device, each layer constituting the organic electroluminescent device has a layer made of an inorganic material as a part of a layer constituting the organic electroluminescent device, in addition to all layers made of an organic material. Research is also being conducted on organic-inorganic hybrid types.
In a conventional organic / inorganic hybrid type organic electroluminescence device, a phosphorescent material is used for the light emitting layer. A structure in which a polyvinylcarbazole polymer added with an iridium compound as a dopant is laminated on a metal oxide layer. Organic organic / inorganic hybrid type organic electroluminescent element (see Non-Patent Document 4) or an organic light emitting layer obtained by adding an iridium compound to poly (9,9-dioctylfluorenyl-2,7-diyl) An inorganic hybrid organic electroluminescent element (see Non-Patent Document 5) is disclosed.

Woo Sik Jeon and five others "Organic Electronics", Vol. 10, 2009, p240-246 7 people outside Tae Jin Park “Applied Physics Letters”, Vol. 92, 2008, p113308 Six people outside of Woo Sik Jeon, “Applied Physics Letters”, Vol. 92, 2008, p113311 Genk J.H. Three people from "Henk J. Bolink" "Advanced Materials", 2010, Vol. 22, p2198-2201 Genk J.H. Two people from "Henck J. Bolink" "Chemistry of Materials", 2009, Vol. 21, p439-441

As described above, an organic electroluminescent element using a phosphorescent material for a light emitting layer has been reported. An organic-inorganic hybrid organic electroluminescent element is considered to be capable of having both flexibility and moldability of an organic component and strength and durability of an inorganic component. In addition, since the resistance to oxygen and water is higher than that of organic electroluminescence devices each layer is composed of only organic compounds, the need for strictly sealing each layer inside the device is reduced, and there are less advantages in manufacturing. have. Because of these characteristics, organic-inorganic hybrid organic electroluminescent elements are highly expected to be put to practical use. On the other hand, the organic / inorganic hybrid type organic electroluminescent device has a further improvement in luminescent properties compared with the organic electroluminescent device in which each layer constituting the organic electroluminescent device is composed of organic materials. Development of an organic-inorganic hybrid organic electroluminescent device with improved characteristics is demanded.

The present invention has been made in view of the above situation, and an object of the present invention is to provide an organic / inorganic hybrid organic electroluminescent device that is more excellent in emission characteristics than conventional organic / inorganic hybrid organic electroluminescent devices. To do.

The inventor conducted various studies on methods for improving the light emission characteristics of the organic / inorganic hybrid type organic electroluminescent device. As a result, the first metal oxide layer, the light emission between the first electrode and the second electrode. An organic electroluminescent device having a structure including a low molecular compound layer including a layer and a second metal oxide layer in this order, and having the light emitting layer of the organic electroluminescent device as a host and having at least one metal complex As a result, the present inventors have found that an organic electroluminescent device having excellent emission characteristics as compared with a conventional organic / inorganic hybrid type organic electroluminescent device has been obtained, and conceived that the above-mentioned problems can be solved brilliantly. It is a thing.

That is, the present invention relates to an organic electroluminescent device having a structure in which a plurality of layers are laminated, and the organic electroluminescent device includes a first metal oxide between a first electrode and a second electrode. An organic electroluminescence comprising: a layer, a low-molecular compound layer including a light-emitting layer, and a second metal oxide layer in this order; and the light-emitting layer includes at least one metal complex that functions as a host. It is an element.
The present invention is described in detail below.
A combination of two or more preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

The organic electroluminescent element of the present invention includes a first metal oxide layer, a low molecular compound layer including a light emitting layer, and a second metal oxide layer between the first electrode and the second electrode. As long as it has in this order, you may have other layers other than these.
In the present invention, the low molecular compound means a compound that is not a polymer compound (polymer), and does not necessarily mean a compound having a low molecular weight.

The organic electroluminescent element of the present invention contains at least one metal complex that functions as a host in the light emitting layer, and a light emitting material that is a low molecular compound is dispersed therein as a guest. By using such a light-emitting layer in which a host-guest, which is a low molecular compound, is combined, the organic electroluminescent device has excellent light emission characteristics such as light emission efficiency and light emission lifetime.
The light emitting material included in the light emitting layer may be one type or two or more types.

The organic electroluminescent element of the present invention has a buffer layer between the first metal oxide layer and the low molecular compound layer including the light emitting layer, and the buffer layer is formed by applying a solution containing an organic compound. A layer having an average thickness of 5 to 100 nm is preferable.
In the organic electroluminescence device of the present invention, when a low molecular compound layer including a light emitting layer is laminated on the first metal oxide layer, crystallization of the low molecular compound layer in contact with the metal oxide layer occurs. As a result, the leakage current increases and the current efficiency is lowered. In the case where the leakage current is remarkable, there is a possibility that a problem that uniform surface light emission cannot be obtained by crystallization may occur. In the organic-inorganic hybrid type organic electroluminescence device, the cause of the crystallization of the low molecular compound layer is considered as follows.
In an organic / inorganic hybrid type organic electroluminescent device, a first electrode disposed on a substrate such as glass and a first metal oxide layer are present, and a low molecular compound layer including a light emitting layer is formed thereon. Will be a film. Here, according to the conventional method, the first metal oxide layer is formed by a spray pyrolysis method, a sol-gel method, a sputtering method, or the like, and the surface is not smooth but has irregularities. When a low molecular compound layer including a light emitting layer is formed on the first metal oxide layer by a method such as vacuum deposition, the surface irregularities of the first metal oxide layer become crystal nuclei, and the first Crystallization of the low molecular compound layer in contact with the metal oxide layer is promoted. For this reason, even if the organic electroluminescent element is completed, a large leak current flows, the light emitting surface becomes non-uniform, and an element that can withstand practical use cannot be obtained.
On the other hand, in the so-called normal structure organic electroluminescence device that does not have the first metal oxide layer on the first electrode, a surface in which the surface of the first electrode is polished sufficiently smoothly is available. Even if a low molecular compound layer including a light emitting layer is directly formed on the surface of the first electrode, the problem of crystallization hardly occurs. Therefore, such crystallization is a problem peculiar to the organic-inorganic hybrid organic electroluminescence device, and is a problem newly generated when a low molecular compound is used as a host of the light emitting layer.
To solve this problem, a buffer layer having an average thickness of 5 to 100 nm is formed by applying a solution containing an organic compound between the first metal oxide layer and the low molecular compound layer including the light emitting layer. In addition, the crystallization of the low-molecular compound in the low-molecular compound layer is suppressed, thereby suppressing the leakage current even when the organic-inorganic hybrid type organic electroluminescent device has a layer formed from the low-molecular compound as a light emitting layer or the like. Thus, uniform surface emission can be obtained.

The low molecular compound layer including the light emitting layer is a layer in which one layer formed of a low molecular compound or a plurality of layers formed of low molecular compounds are stacked, and one of the layers emits light. What is a layer. That is, a low molecular compound layer including a light emitting layer is a light emitting layer formed of a low molecular compound, or a light emitting layer formed of a low molecular compound and another layer formed of a low molecular compound. One of things. The other layer formed by the low molecular compound may be one layer or two or more layers. The order in which the light emitting layer and other layers are stacked is not particularly limited.

The other layer formed of the low molecular compound is preferably a hole transport layer or an electron transport layer. That is, when the low molecular compound layer is composed of a plurality of layers, it is preferable to have a hole transport layer and / or an electron transport layer as other layers other than the light emitting layer. Thus, it is one of the preferred embodiments of the organic electroluminescent device of the present invention that the organic electroluminescent device has a hole transport layer and / or an electron transport layer as an independent layer different from the light emitting layer. is there.
When the organic electroluminescent element of the present invention has a hole transport layer as an independent layer, it is preferable to have a hole transport layer between the light emitting layer and the second metal oxide layer. When the organic electroluminescent element of the present invention has an electron transport layer as an independent layer and also has the above-described buffer layer, it may have an electron transport layer between the buffer layer formed from the organic compound and the light emitting layer. preferable.
When the organic electroluminescent device of the present invention does not have a hole transport layer or an electron transport layer as an independent layer, any of the layers possessed as an essential component of the organic electroluminescent device of the present invention functions as these layers. It will also serve as.

One of the preferred embodiments of the organic electroluminescent device of the present invention is that the organic electroluminescent device is a first electrode, a first metal oxide layer, a buffer layer formed from an organic compound, a light emitting layer, and a hole transport layer. The second metal oxide layer is composed of only the second electrode, and any one of these layers also serves as the electron transport layer.
In addition, the organic electroluminescent element includes only the first electrode, the first metal oxide layer, the buffer layer formed from the organic compound, the light emitting layer, the second metal oxide layer, and the second electrode. A form in which any one of these layers also functions as a hole transport layer and an electron transport layer is also one of the preferred forms of the organic electroluminescence device of the present invention.

In the organic electroluminescent element of the present invention, the first electrode is a cathode and the second electrode is an anode. Examples of the first electrode include ITO (indium tin oxide), IZO (indium zinc oxide), FTO (fluorine tin oxide), oxides such as In ₃ O ₃ , SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO. Can be mentioned. Among these, ITO, IZO, and FTO are preferable.
Examples of the second electrode include Au, Pt, Ag, Cu, Al, and alloys containing these. Among these, Au, Ag, and Al are preferable.

The average thickness of the first electrode is not particularly limited, but is preferably 10 to 500 nm. More preferably, it is 100-200 nm. The average thickness of the first electrode can be measured by a stylus profilometer or spectroscopic ellipsometry.
The average thickness of the second electrode is not particularly limited, but is preferably 10 to 1000 nm. More preferably, it is 30-150 nm. Even when an opaque material is used, for example, by setting the average thickness to about 10 to 30 nm, it can be used as a top emission type or transparent type anode.
The average thickness of the second electrode can be measured at the time of film formation by a crystal oscillator thickness meter.

The first metal oxide layer functions as an electron injection layer, and the second metal oxide layer functions as a hole injection layer.
The first metal oxide layer is not particularly limited, titanium oxide _(TiO 2), zinc oxide (ZnO), tungsten oxide _(WO 3), niobium oxide _{(Nb 2 O} 5), iron oxide (Fe ₂ One or more of O ₃ ), tin oxide (SnO ₂ ), magnesium oxide (MgO), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ) and the like can be used.

The second metal oxide layer is not particularly limited, but one or more of vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₃ ), ruthenium oxide (RuO ₂ ), and the like may be used. it can. Among these, those containing vanadium oxide or molybdenum oxide as a main component are preferable. When the second metal oxide layer is composed of vanadium oxide or molybdenum oxide as a main component, the second metal oxide layer injects holes from the second electrode and emits light or transports holes. The function as a hole injection layer of transporting to a layer is superior. In addition, since vanadium oxide or molybdenum oxide itself has a high hole transport property, it is also possible to suitably prevent the efficiency of hole injection from the second electrode to the light emitting layer or the hole transport layer from being lowered. There is an advantage that you can. More preferably, it is composed of vanadium oxide and / or molybdenum oxide.

The average thickness of the first metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 2 to 100 nm.
The average thickness of the second metal oxide layer is not particularly limited, but is preferably 1 to 1000 nm. More preferably, it is 5-50 nm.
The average thickness of the first metal oxide layer can be measured by a stylus profilometer or spectroscopic ellipsometry.
The average thickness of the second metal oxide layer can be measured at the time of film formation with a crystal oscillator thickness meter.

The light emitting layer of the organic electroluminescent element of the present invention has a metal complex as a host. The host of the light emitting layer has a role of moving the energy and electrons to and from the guest to bring the guest into an excited state, and the excitation energy of the host that moves energy and electrons to and from the guest is the excitation energy of the guest Is preferably larger. The metal complex used as the host of the light emitting layer can be used as long as it has electrical conductivity and is an amorphous material and has such a relationship with the light emitting material used as the host. As a metal complex used as a host, the following formula (1);

(In the formula, a dotted arc represents that a ring structure is formed together with a part of the skeleton part connecting the oxygen atom and the nitrogen atom, and the ring structure formed including Z and the nitrogen atom is complex. X ^′ and X ^″ are the same or different and each represents a hydrogen atom or a monovalent substituent serving as a substituent of the ring structure, and a plurality of ring structures forming a dotted arc portion. X ^′ and X ^″ may combine to form a new ring structure together with a part of two ring structures represented by dotted arcs. A dotted line in a skeleton portion connecting the two represents that two atoms connected by the dotted line are bonded by a single bond or a double bond, M represents a metal atom, and Z represents a carbon atom or a nitrogen atom. The arrow from the nitrogen atom to M indicates that the nitrogen atom is coordinated to the M atom, R ⁰ is a monovalent Represents a substituent or a divalent linking group, m represents the number of R ^{0 and is} a number of 0 or 1. n represents the valence of the metal atom M. r is the number of 1 or 2. Metal complex represented by
Following formula (2);

(Wherein X ^′ and X ^″ are the same or different and each represents a hydrogen atom or a monovalent substituent serving as a substituent of the quinoline ring structure, and a plurality of them may be bonded to the quinoline ring structure. M represents a metal atom, an arrow from a nitrogen atom to M represents that the nitrogen atom is coordinated to an M atom, and R ⁰ represents a monovalent substituent or a divalent linking group. M represents the number of R ^{0 and is} a number of 0 or 1. n represents the valence of the metal atom M. r is the number of 1 or 2.)
Following formula (3);

(In the formula, a dotted arc represents that a ring structure is formed together with a part of the skeleton part connecting the oxygen atom and the nitrogen atom, and the ring structure formed including Z and the nitrogen atom is complex. X ^′ and X ^″ are the same or different and each represents a hydrogen atom or a monovalent substituent serving as a substituent of the ring structure, and a plurality of ring structures forming a dotted arc portion. X ^′ and X ^″ may combine to form a new ring structure together with a part of two ring structures represented by dotted arcs. A dotted line in a skeleton portion connecting the two represents that two atoms connected by the dotted line are bonded by a single bond or a double bond, M represents a metal atom, and Z represents a carbon atom or a nitrogen atom. The arrow from the nitrogen atom to M indicates that the nitrogen atom is coordinated to the M atom, where n is a metal atom. Ring valence solid arcs connecting the .X ^a and X ^b representing a represents that the X ^a and X ^b are bonded via at least one other atom, together with X ^a and X ^b structure may be formed. in addition at least one other atom via a X ^a and X ^b with good .X a also include coordinate bonds in the ^bond, X ^b are the same or different Represents an oxygen atom, a nitrogen atom, or a carbon atom, and an arrow from ^Xb to M represents that ^Xb is coordinated to an M atom, and m ′ is a number from 1 to 3. A metal complex represented by the formula (1)), and one or more of these can be used.

In the above formula (1), when r is 1, a metal complex represented by the following formula (4-1) having one M atom in the structure is obtained, and when r is 2, M atom is in the structure. It becomes a metal complex represented by the following formula (4-2).

In the above formulas (1) and (3), the ring structure represented by the dotted arc may be a ring structure consisting of one ring or a ring structure consisting of two or more rings. . Examples of such a ring structure include aromatic rings and heterocyclic rings having 2 to 20 carbon atoms, and aromatic rings such as benzene ring, naphthalene ring and anthracene ring; diazole ring, thiazole ring, isothiazole ring, oxazole ring, Oxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, imidazole ring, imidazoline ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, diazine ring, triazine ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, Heterocycles such as a benzotriazole ring can be mentioned.
Among these, benzene ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, imidazole ring, imidazoline ring, pyridine ring, pyridazine ring, pyrimidine ring, benzimidazole ring , A benzothiazole ring, a benzoxazole ring, and a benzotriazole ring are preferable.

In the above formulas (1) to (3), the substituent that the ring structure represented by X ^′ and X ^″ has as a halogen atom, an alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, carbon An aralkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, an alkenyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, an aryl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, Arylamino group, cyano group, amino group, acyl group, C1-C20, preferably C1-C10 alkoxycarbonyl group, carboxyl group, C1-C20, preferably C1-C10 alkoxy group An alkylamino group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, a dialkylamino group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. The Alla Kiruamino group, having 1 to 20 carbon atoms, preferably a haloalkyl group having 1 to 10 carbon atoms, a hydroxyl group, an aryloxy group, and a carbazolyl group.
In addition, when the substituent which the ring structure represented by X ^′ and X ^″ has is an aryl group or an arylamino group, the aromatic ring contained in the aryl group or arylamino group may further have a substituent. Often, the substituents in that case are the same as the specific examples of the substituents represented by X ^′ and X ^″ .

A new ring is formed together with a part of the two ring structures represented by dotted arcs by combining substituents of the two ring structures represented by dotted arcs represented by the above formulas (1) and (3). When forming a structure, examples of the newly formed ring structure include a 5-membered ring structure and a 6-membered ring structure. The ring structure is a combination of two ring structures represented by dotted arcs and the new ring structure. Examples of the structure include the following structures (5-1) and (5-2).

In the above formulas (1) to (3), the metal atom represented by M is preferably a metal atom of Group 1, Group 3, Group 10, Group 10, Group 12 or Group 13 of the periodic table, zinc, aluminum Any of gallium, platinum, rhodium, iridium, beryllium, and magnesium is preferable.

In the above formulas (1) and (2), when R ⁰ is a monovalent substituent, the monovalent substituent may be any of the following formulas (6-1) to (6-3). preferable.

(In the formula, Ar ^{1 to} Ar ⁵ represent an aromatic ring, a heterocyclic ring, or a structure in which two or more aromatic rings or heterocyclic rings are directly bonded, and Ar ^{3 to} Ar ^5. May be the same structure or different structures. Q ⁰ represents a silicon atom or a germanium atom.)
Specific examples of the aromatic ring or heterocyclic ring of Ar ^{1 to} Ar ⁵ include the same examples as the specific examples of the aromatic ring or heterocyclic ring having the ring structure represented by the dotted arc in the above formula (1). Examples of the structure in which two or more aromatic rings or heterocyclic rings are directly bonded include a structure in which two or more ring structures mentioned as specific examples of these aromatic rings or heterocyclic rings are directly bonded. In this case, the two or more aromatic rings or heterocyclic rings directly bonded may have the same ring structure or different ring structures.
Specific examples of the substituent for the aromatic ring or the heterocyclic ring include the same examples as the specific examples of the substituent for the aromatic ring or the heterocyclic ring having a ring structure represented by the dotted arc in the above formula (1). .
Also,

In the above formulas (1) and (2), when R ⁰ is a divalent linking group, R ⁰ is preferably either —O— or —CO—.

In the above formula (3), X ^a, and X ^b, structure formed by the solid line arc connecting the X ^a and X ^b may include one or more ring structures. The ring structure may include X ^a and X ^b, and the ring structure in that case is the same as the ring structure represented by the dotted arc in the above formulas (1) and (3). And a pyrazole ring. A structure in which a pyrazole ring is formed including X ^a and X ^b is preferable.

In the above formula (3), the solid arc connecting X ^a and X ^b may be composed of only carbon atoms or may contain other atoms. Examples of other atoms include a boron atom, a nitrogen atom, and a sulfur atom.
The solid line arc connecting the X ^a and X ^b is, X ^a, the ring structure other than the ring structure formed including a X ^b may include one or more, as a ring structure of the case Is the same as the ring structure represented by the dotted arc in the above formulas (1) and (3), and a pyrazole ring.

Examples of the structure represented by the above formula (3) include the structure of the following formula (7).

(In Formula (7), R < ¹ > -R < ³ > is the same or different and represents a hydrogen atom or a monovalent substituent. The arrow from a nitrogen atom to M and the arrow from an oxygen atom to M are a nitrogen atom, This represents that the oxygen atom is coordinated to the M atom, the dotted arc, the dotted line in the skeleton connecting the oxygen atom and the nitrogen atom, X ^′ , X ^″ , M, Z, n, m ′ (Same as (3).)
Examples of the monovalent substituent of R ^{1 to} R ^{3 in} the formula (7) include the same substituents as those in the ring structure represented by X ^′ and X ^″ in the above formulas (1) to (3). Can be mentioned.

Specific examples of the compound represented by the above formula (1) include compounds having structures represented by the following formulas (8-1) to (8-40).

Specific examples of the compound represented by the above formula (2) include compounds having structures represented by the following formulas (9-1) to (9-3).

Specific examples of the compound represented by the above formula (3) include compounds having structures represented by the following formulas (10-1) to (10-8).

As the metal complex in the present invention, one or more of the above-mentioned compounds can be used. Among these, bis [2- (2-benzothiazolyl) phenolate represented by the above formula (8-11)] Zinc, bis (10-hydroxybenzo [h] quinolinato) beryllium (Bebq ₂ ) represented by the above formula (8-34), bis [2- (2-hydroxyphenyl) represented by the above formula (8-35) ) -Pyridine] beryllium (Bep ₂ ) is preferred.

The light emitting layer of the organic electroluminescent element of the present invention preferably contains a phosphorescent material. By including the phosphorescent light emitting material as a guest, the organic electroluminescent element of the present invention is superior in light emission efficiency and light emission lifetime.
As the phosphorescent material, a compound represented by any of the following formulas (11) and (12) can be suitably used.

(In the formula (11), a dotted arc represents that a ring structure is formed together with a part of the skeleton part composed of oxygen atoms and three carbon atoms, and a ring formed including nitrogen atoms. The structure is a heterocyclic structure. X ^′ and X ^″ are the same or different and each represents a hydrogen atom or a monovalent substituent that serves as a substituent of the ring structure, and forms a dotted arc portion. A plurality of bonds may be bonded to the structure. X ^′ and X ^″ may combine to form a new ring structure together with a part of two ring structures represented by dotted arcs. When n is 2 or more, a plurality of X ^′ or X ^″ may be bonded to each other to form one substituent. A skeleton part composed of a nitrogen atom and three carbon atoms A dotted line in represents that two atoms connected by the dotted line are bonded by a single bond or a double bond. From. The nitrogen atom represent children M 'arrow to the nitrogen atom is M' .n representing that they are coordinated to atoms, represents the valence of the metal atom M '.)

(In the formula (12), a dotted arc represents that a ring structure is formed together with a part of a skeleton composed of an oxygen atom and three carbon atoms, and a ring formed including a nitrogen atom. The structure is a heterocyclic structure. X ^′ and X ^″ are the same or different and each represents a hydrogen atom or a monovalent substituent that serves as a substituent of the ring structure, and forms a dotted arc portion. A plurality of bonds may be bonded to the structure. X ^′ and X ^″ may combine to form a new ring structure together with a part of two ring structures represented by dotted arcs. And a dotted line in a skeleton portion composed of three carbon atoms represents that two atoms connected by the dotted line are bonded by a single bond or a double bond, and M ′ represents a metal atom. The arrow from to M ′ indicates that the nitrogen atom is coordinated to the M ′ atom, where n is the valence of the metal atom M ′. The solid line arc connecting the .X ^a and X ^b representing the number, represents that the X ^a and X ^b are bonded via at least one other atom, the ring structure with X ^a and X ^b X ^a and X ^b are the same or different and each represents an oxygen atom, a nitrogen atom, or a carbon atom, and the arrow from X ^b to M ′ indicates that X ^b is an M ′ atom. (It represents a coordination. M ′ is a number from 1 to 3.)

Examples of the ring structure represented by the dotted arc in the above formulas (11) and (12) include C2-C20 aromatic rings and heterocyclic rings, and aromatics such as benzene rings, naphthalene rings, and anthracene rings. Hydrocarbon ring; pyridine ring, pyrimidine ring, pyrazine ring, triazine ring, benzothiazole ring, benzothiol ring, benzoxazole ring, benzoxol ring, benzimidazole ring, quinoline ring, isoquinoline ring, quinoxaline ring, and phenanthridine And heterocyclic rings such as a ring, a thiophene ring, a furan ring, a benzothiophene ring, and a benzofuran ring.

The formula (11) and Equation (12) X In ^', X' as the substituent represented by ^'the formula (1) X ^at', X 'include the same substituents represented ^by' It is done.
In the above formulas (11) and (12), the substituents of the two ring structures represented by dotted arcs are bonded together to form a new ring together with a part of the two ring structures represented by dotted arcs. In the case where the structure is formed, examples of the ring structure in which the two ring structures represented by the dotted arc and the new ring structure are combined include structures such as the above (5-1) and (5-2). Is mentioned.

In the above formulas (11) and (12), examples of the metal atom represented by M ′ include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.

Examples of the structure represented by the above formula (12) include the structures of the following formulas (13-1) and (13-2).

(In formulas (13-1) and (13-2), R ^{1 to} R ³ are the same or different and each represents a hydrogen atom or a monovalent substituent. In formula (13-2), R ^{1 to} R 3 ^{When 3} is a monovalent substituent, the ring structure may have a plurality of monovalent substituents, an arrow from a nitrogen atom to M ′ and an arrow from an oxygen atom to M ^′ represent a nitrogen atom, This represents that the oxygen atom is coordinated to the M ′ atom, a dotted arc, a dotted line in a skeleton composed of a nitrogen atom and three carbon atoms, X ^′ , X ^″ , M ′, n, m 'Is the same as in equation (12).)
Examples of the monovalent substituent of R ^{1 to} R ³ include the same substituents as those in the ring structures represented by X ^′ and X ^″ in the above formulas (1) to (3).

Specific examples of the compound represented by the above formula (11) or formula (12) include compounds represented by the following formulas (14-1) to (14-30).

As the phosphorescent material in the present invention, one or more of the above-mentioned materials can be used. Among these, iridium tris (2-phenylpyridine) represented by the above formula (14-1) ( Ir (ppy) ₃ ), iridium tris (1-phenylisoquinoline) represented by the above formula (14-19) (Ir (piq) ₃ ), iridium bis (2- (2-27) represented by the above formula (14-27) Methyldibenzo- [f, h] quinoxaline) (acetylacetonate) (Ir (MDQ) ₂ (acac)), iridium tris [3-methyl-2-phenylpyridine] represented by the above formula (14-28) ( Ir (mpy) ₃ ) and the like are preferable.

It is preferable that content of the phosphorescence-emitting material in the said light emitting layer is 0.5-20 mass% with respect to 100 mass% of materials which form a light emitting layer. With such a content, the light emission characteristics can be improved. More preferably, it is 0.5-10 mass%, More preferably, it is 1-6 mass%.

The light emitting layer of the organic electroluminescent element of the present invention may contain a low molecular compound other than the metal complex functioning as the host and the phosphorescent light emitting material.
Examples of such low molecular weight compounds include 8-hydroxyquinoline aluminum (Alq ₃ ), tris (4-methyl-8 quinolinolate) aluminum (III) (Almq ₃ ), 8-hydroxyquinoline zinc (Znq ₂ ), (1, 10-phenanthroline) -tris- (4,4,4-trifluoro-1- (2-thienyl) -butane-1,3-dionate) europium (III) (Eu (TTA) ₃ (phen)), 2, Various metal complexes such as 3,7,8,12,13,17,18-octaethyl-21H, 23H-porphine platinum (II); benzene such as distyrylbenzene (DSB) and diaminodistyrylbenzene (DADSB) Compounds, naphthalene, naphthalene compounds such as Nile Red, phenanes such as phenanthrene Len compounds, chrysene, chrysene compounds such as 6-nitrochrysene, perylene, N, N'-bis (2,5-di-t-butylphenyl) -3,4,9,10-perylene-di- Perylene compounds such as carboximide (BPPC), coronene compounds such as coronene, anthracene compounds such as anthracene and bisstyrylanthracene, pyrene compounds such as pyrene, 4- (di-cyanomethylene) -2 -Pyran compounds such as methyl-6- (para-dimethylaminostyryl) -4H-pyran (DCM), acridine compounds such as acridine, stilbene compounds such as stilbene, 4,4'-bis [9 -Dicarbazolyl] -2,2'-biphenyl (CBP), 4,4'-bis (9-ethyl-3-carbazovinylene) -1 Carbazole compounds such as 1′-biphenyl (BCzVBi), thiophene compounds such as 2,5-dibenzoxazolethiophene, benzoxazole compounds such as benzoxazole, benzimidazole compounds such as benzimidazole, 2, Benzothiazole compounds such as 2 '-(para-phenylenedivinylene) -bisbenzothiazole, bistyryl (1,4-diphenyl-1,3-butadiene), butadiene compounds such as tetraphenylbutadiene, naphthalimide Naphthalimide compounds, coumarin compounds such as coumarin, perinone compounds such as perinone, oxadiazole compounds such as oxadiazole, aldazine compounds, 1,2,3,4,5-penta Phenyl-1,3-si Cyclopentadiene compounds such as lopentadiene (PPCP), quinacridone compounds such as quinacridone and quinacridone red, pyridine compounds such as pyrrolopyridine and thiadiazolopyridine, 2,2 ′, 7,7′-tetraphenyl Spiro compounds such as -9,9′-spirobifluorene, metal or metal-free phthalocyanine compounds such as phthalocyanine (H ₂ Pc) and copper phthalocyanine, and Japanese Patent Application Laid-Open No. 2009-155325 and Japanese Patent Application 2010- Examples thereof include boron compound materials described in No. 28273, and one or more of these materials can be used.

In the light emitting layer of the organic electroluminescent element of the present invention, the content ratio of the low molecular weight compound other than the metal complex that functions as a host and the guest material is 0.5 to 100% by mass of the material forming the light emitting layer. It is preferably 20% by mass. With such a content, the light emission characteristics can be improved. More preferably, it is 0.5-10 mass%, More preferably, it is 1-6 mass%.

Although the average thickness of the said light emitting layer is not specifically limited, It is preferable that it is 10-150 nm. More preferably, it is 20-100 nm.
The average thickness of the light emitting layer can be measured at the time of film formation with a quartz oscillator film thickness meter.

As the material for the hole transport layer, any low molecular weight compound that can be usually used as the material for the hole transport layer can be used, and these may be used in combination.
Examples of the low molecular weight compound include 1,1-bis (4-di-para-triaminophenyl) cyclohexane and 1,1′-bis (4-di-para-tolylaminophenyl) -4-phenyl-cyclohexane. Such arylcycloalkane compounds, 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetraphenyl-1,1′-biphenyl-4,4′-diamine, N , N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (TPD1), N, N′-diphenyl-N, N′-bis ( 4-methoxyphenyl) -1,1′-biphenyl-4,4′-diamine (TPD2), N, N, N ′, N′-tetrakis (4-methoxyphenyl) -1,1′-biphenyl-4, 4′-diamine (TPD3), N, N′-di (1-na Til) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine (α-NPD), arylamine compounds such as TPTE, N, N, N ′, N′-tetraphenyl -Para-phenylenediamine, N, N, N ', N'-tetra (para-tolyl) -para-phenylenediamine, N, N, N', N'-tetra (meta-tolyl) -meta-phenylenediamine ( Phenylenediamine compounds such as PDA), carbazole compounds such as carbazole, N-isopropylcarbazole, N-phenylcarbazole, stilbenes, stilbene compounds such as 4-di-para-tolylaminostilbene, and OxZ Oxazole compounds, triphenylmethane, triphenylmethane compounds such as m-MTDATA, 1-phenyl-3- (para -Pyrazoline compounds such as dimethylaminophenyl) pyrazoline, benzine (cyclohexadiene) compounds, triazole compounds such as triazole, imidazole compounds such as imidazole, 1,3,4-oxadiazole, 2,5 -Oxadiazole compounds such as di (4-dimethylaminophenyl) -1,3,4, -oxadiazole, anthracene, anthracene compounds such as 9- (4-diethylaminostyryl) anthracene, fluorenone, 2 , 4,7, -trinitro-9-fluorenone, 2,7-bis (2-hydroxy-3- (2-chlorophenylcarbamoyl) -1-naphthylazo) fluorenone, aniline compounds such as polyaniline , Silane compounds, 1,4-di Pyrrole compounds such as oketo-3,6-diphenyl-pyrrolo- (3,4-c) pyrrolopyrrole, fluorene compounds such as fluorene, porphyrins, porphyrin compounds such as metal tetraphenylporphyrin, quinacridone Quinacridone compounds, metal such as phthalocyanine, copper phthalocyanine, tetra (t-butyl) copper phthalocyanine, iron phthalocyanine or metal-free phthalocyanine compounds, metal such as copper naphthalocyanine, vanadyl naphthalocyanine, monochlorogallium naphthalocyanine or Metal-free naphthalocyanine compounds, benzidine compounds such as N, N′-di (naphthalen-1-yl) -N, N′-diphenyl-benzidine, N, N, N ′, N′-tetraphenylbenzidine Etc. It can be used alone or in combination of these.
Among these, arylamine compounds such as α-NPD and TPTE are preferable.

When the organic electroluminescent element of the present invention has a hole transport layer as an independent layer, the average thickness of the hole transport layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 40-100 nm.
The average thickness of the hole transport layer can be measured at the time of film formation using a quartz oscillator thickness meter.

As the material for the electron transport layer, any low molecular weight compound that can be usually used as the material for the electron transport layer can be used, or a mixture of these may be used.
Examples of the low molecular weight compound that can be used as the material for the electron transport layer include tris-1,3,5- (3 ′-(pyridine-3) in addition to a boron-containing compound represented by the formula (15) described later. Pyridine derivatives such as '' -yl) phenyl) benzene (TmPyPhB), quinoline derivatives such as (2- (3- (9-carbazolyl) phenyl) quinoline (mCQ)), 2-phenyl-4,6-bis Pyrimidine derivatives such as (3,5-dipyridylphenyl) pyrimidine (BPyPPM), pyrazine derivatives, phenanthroline derivatives such as bathophenanthroline (BPhen), 2,4-bis (4-biphenyl) -6- (4 ′-( Triazine derivatives such as 2-pyridinyl) -4-biphenyl)-[1,3,5] triazine (MPT), 3-phenyl-4- (1 ′ Triazole derivatives such as naphthyl) -5-phenyl-1,2,4-triazole (TAZ), oxazole derivatives, 2- (4-biphenylyl) -5- (4-tert-butylphenyl-1,3,4) Oxadiazole derivatives such as (oxadiazole) (PBD), 2,2 ′, 2 ″-(1,3,5-benztriyl) -tris (1-phenyl-1-H-benzimidazole) (TPBI) Imidazole derivatives such as, aromatic ring tetracarboxylic anhydrides such as naphthalene and perylene, bis [2- (2-hydroxyphenyl) benzothiazolate] zinc (Zn (BTZ) ₂ ), tris (8-hydroxyquinolinato) aluminum ( Various metal complexes represented by Alq3), 2,5-bis (6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3 , 4-diphenylsilole (PyPySPyPy) and other organic silane derivatives represented by silole derivatives, and one or more of these can be used.
Among these, a metal complex such as Alq ₃ and a pyridine derivative such as TmPyPhB are preferable.

When the organic electroluminescent element of the present invention has an electron transport layer as an independent layer, the average thickness of the electron transport layer is not particularly limited, but is preferably 10 to 150 nm. More preferably, it is 40-100 nm.
The average thickness of the electron transport layer can be measured at the time of film formation with a crystal oscillator thickness meter.

In the organic electroluminescence device of the present invention, the method for forming the first and second metal oxide layers, the second electrode, the light emitting layer, the hole transport layer, and the electron transport layer is not particularly limited, and vapor phase film formation is performed. Chemical vapor deposition (CVD) methods such as plasma CVD, thermal CVD, and laser CVD, dry plating methods such as vacuum deposition, sputtering, and ion plating, thermal spraying methods, and electrolytic plating and immersion plating that are liquid phase film forming methods. , Wet plating methods such as electroless plating, sol-gel method, MOD method, spray pyrolysis method, doctor blade method using fine particle dispersion, spin coating method, ink jet method, screen printing method, etc. It is possible to select and use an appropriate method according to the material.

In the organic electroluminescent element of the present invention, the buffer layer described above is preferably a layer formed by applying a solution containing an organic compound. By forming a buffer layer having a predetermined thickness by coating, it is possible to effectively suppress crystallization of a low molecular compound formed on the buffer layer.
The method for applying the solution containing the organic compound is not particularly limited, and spin coating method, casting method, gravure coating method, bar coating method, roll coating method, dip coating method, spray coating method, screen printing method, offset printing method. Various coating methods such as an ink jet printing method can be used. Among these, the spin coat method is preferable.
By coating and forming the buffer layer, the unevenness present on the surface of the first metal oxide layer is smoothed, so that crystallization of the low molecular compound to be formed next on the buffer layer is suppressed.

The solvent used for preparing the solution containing the organic compound is not particularly limited as long as it can dissolve the organic compound. Tetrahydrofuran (THF), toluene, xylene, chloroform, dichloromethane, dichloroethane, chlorobenzene 1 type, or 2 or more types can be used. Among these, THF, toluene, chloroform, and dichloroethane are preferable.

The solution containing the organic compound preferably has a concentration of the organic compound in the solvent of 0.05 to 10% by mass. With such a concentration, it is possible to suppress the occurrence of uneven coating and unevenness when applied. The concentration of the organic compound in the solvent is more preferably 0.1 to 5% by mass, and still more preferably 0.1 to 3% by mass.

The buffer layer preferably has an average thickness of 5 to 100 nm. When the average thickness is within such a range, the effect of suppressing crystallization of the low molecular compound layer including the light emitting layer can be sufficiently exhibited. If the average thickness of the buffer layer is less than 5 nm, the unevenness present on the surface of the first metal oxide cannot be sufficiently smoothed, and the effect of forming the buffer layer due to an increase in leakage current is sufficiently exhibited. There is a risk that it will not be possible. On the other hand, when the average thickness of the buffer layer is larger than 100 nm, the driving voltage is increased, which is not practically preferable. Further, when a compound having a preferable structure in the present invention described later is used as the organic compound, the buffer layer can sufficiently exhibit the function as the electron transport layer. The average thickness of the buffer layer is more preferably 10 to 60 nm.
The average thickness of the buffer layer can be measured by a stylus profilometer or spectroscopic ellipsometry.

The organic electroluminescent element of the present invention may be one in which each layer constituting the organic electroluminescent element is laminated on a substrate. When each layer is laminated on the substrate, it is preferable that each layer is formed on the first electrode formed on the substrate. In this case, the organic electroluminescent element of the present invention may be a top emission type that extracts light to the side opposite to the side where the substrate is present, or a bottom emission type that extracts light to the side where the substrate is present. May be.

As the material of the substrate, resin materials such as polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, polyarylate, quartz glass, soda glass, etc. A glass material etc. are mentioned, These 1 type (s) or 2 or more types can be used.
In the case of the top emission type, an opaque substrate can be used. For example, an oxide film (insulating film) is formed on the surface of a ceramic substrate such as alumina or a metal substrate such as stainless steel. A substrate made of a resin material or the like can also be used.

The average thickness of the substrate is preferably 0.1 to 30 mm. More preferably, it is 0.1-10 mm.
The average thickness of the substrate can be measured with a digital multimeter or a caliper.

In the organic electroluminescent element of the present invention, the organic compound forming the buffer layer is not particularly limited as long as it can form a layer of the organic compound by coating. Examples of the organic compound include trans-type polyacetylene, cis Type polyacetylene, poly (di-phenylacetylene) (PDPA), polyacetylene-based compounds such as poly (alkyl, phenylacetylene) (PAPA); poly (para-phenvinylene) (PPV), poly (2,5-dialkoxy) -Para-phenylenevinylene) (RO-PPV), cyano-substituted-poly (para-phenvinylene) (CN-PPV), poly (2-dimethyloctylsilyl-para-phenylenevinylene) (DMOS-PPV), poly ( 2-methoxy, 5- (2′-ethylhexoxy) -para-phenylenevinylene) Polyparaphenylene vinylene compounds such as MEH-PPV; polythiophene compounds such as poly (3-alkylthiophene) (PAT), poly (oxypropylene) triol (POP); poly (9,9-dioctylfluorene) Poly (9,9-dialkylfluorene) (PDAF), poly (dioctylfluorene-alt-benzothiadiazole) (F8BT), α, ω-bis [N, N′-di (methylphenyl) aminophenyl] -poly [9,9-bis (2-ethylhexyl) fluorene-2,7-zyl] (PF2 / 6am4), poly (9,9-dioctyl-2,7-divinylenefluorenyl-ortho-co (anthracene-9) , 10-diyl) such as polyfluorene compounds; poly (para-phenylene) (PPP), poly Polyparaphenylene compounds such as (1,5-dialkoxy-para-phenylene) (RO-PPP); polycarbazole compounds such as poly (N-vinylcarbazole) (PVK); poly (methylphenylsilane) Examples thereof include polysilane compounds such as (PMPS), poly (naphthylphenylsilane) (PNPS), poly (biphenylylphenylsilane) (PBPS), and boron-containing compounds represented by the following formula (15). These may use 1 type and may use 2 or more types.

The buffer layer preferably contains a reducing agent. Since the reducing agent functions as an n-dopant, the buffer layer contains the reducing agent, so that electrons are sufficiently supplied from the cathode to the light emitting layer, so that the light emission efficiency is improved.
The reducing agent included in the buffer layer is not particularly limited as long as it is an electron donating compound, but 1,3-dimethyl-2,3-dihydro-1H-benzo [d] imidazole, 1,3-dimethyl-2- Phenyl-2,3-dihydro-1H-benzo [d] imidazole, (4- (1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl) phenyl) dimethylamine (N-DMBI) 2,3-dihydrobenzo [d] imidazole compounds such as 1,3,5-trimethyl-2-phenyl-2,3-dihydro-1H-benzo [d] imidazole; 2,3-dihydrobenzo [d] thiazole compounds such as 3-dihydrobenzo [d] thiazole; 3-methyl-2-phenyl-2,3-dihydrobenzo [d] oxazole 2,3-dihydrobenzo [d] oxazole compounds; leucocrystal violet (= tris (4-dimethylaminophenyl) methane), leucomalachite green (= bis (4-dimethylaminophenyl) phenylmethane), triphenylmethane, etc. 1 type, or 2 or more types, such as dihydropyridine compounds, such as a triphenylmethane compound; Diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate (Huntuester), etc. can be used. Among these, 2,3-dihydrobenzo [d] imidazole compounds and dihydropyridine compounds are preferable. More preferably, (4- (1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl) phenyl) dimethylamine (N-DMBI) or 2,6-dimethyl-1,4- Dihydropyridine-3,5-dicarboxylate diethyl (Huntuester).

The amount of the reducing agent contained in the buffer layer is preferably 0.1 to 15% by mass with respect to 100% by mass of the organic compound forming the buffer layer. When the reducing agent is contained in such a ratio, the luminous efficiency of the organic electroluminescent element can be made sufficiently high. More preferably, it is 0.5-10 mass% with respect to 100 mass% of organic compounds which form a buffer layer, More preferably, it is 1-5 mass%.

In the organic electroluminescent element of the present invention, the organic compound forming the buffer layer is preferably an organic compound having a boron atom. More preferably, the organic compound having a boron atom is a compound having a structure represented by the following formula (15).
That is, in the organic electroluminescent element of the present invention, the organic compound having a boron atom forming the buffer layer is represented by the following formula (15);

(In the formula, a dotted arc indicates that a ring structure is formed together with a skeleton represented by a solid line. The dotted line in the skeleton represented by a solid line has two pairs of atoms connected by a dotted line. The arrows from the nitrogen atom to the boron atom indicate that the nitrogen atom is coordinated to the boron atom, and Q ¹ and Q ² are the same or different, X ¹ , X ² , X ^3, and X are linking groups in the skeleton represented by the solid line, at least a part of which forms a ring structure together with the dotted arc portion. ⁴ are the same or different and each represents a hydrogen atom or a monovalent substituent serving as a substituent of the ring structure, and a plurality of n ¹ may be bonded to the ring structure forming the dotted arc portion. represents an integer of 2 to 10 .Y ¹ linking groups der direct bond or ^{n 1} monovalent Independently and structural parts other than ^{Y 1} present ^{one n,} ring structure to form an arc portion of the dotted ^line, at any one location in the ^{Q 1, Q 2, X 1} , X 2, X 3, X 4 It is preferably a boron-containing compound represented by the following formula:

In the organic / inorganic hybrid electroluminescent device, hole injection from the anode occurs more efficiently than electron injection from the cathode, and the light emission position is present near the interface of the cathode side oxide (corresponding to the first metal oxide in the present invention). It is known to do. In order to avoid light emission from the buffer layer in contact with the first metal oxide layer, the organic compound forming the buffer layer is a compound having a HOMO level deeper than the HOMO level of the light-emitting compound contained in the light-emitting layer. It is preferable to select. Furthermore, in order to avoid the emission of exciton energy generated in the light emitting layer to the buffer layer compound, the HOMO-LUMO energy gap is wider than the HOMO-LUMO energy gap of the light emitting compound contained in the light emitting layer. More preferably, the compound is selected. The boron-containing compound represented by the above formula (15) has a very deep HOMO and a wide HOMO-LUMO energy gap, and is a coatable compound, so that it can function effectively for various types of light emitting layers. it can.
In addition, when the organic compound having a boron atom is a compound having such a structure, the buffer layer formed from the organic compound has an excellent function as an electron transport layer, and the electron transport layer is separated from the buffer layer. There is no need to provide it.

The boron-containing compound represented by the formula (15) is (i) a thermally stable compound, (ii) low energy levels of HOMO and LUMO, and (iii) producing a good coating film. Therefore, it can be suitably used as the material of the organic electroluminescence device of the present invention.

In the above formula (15), dotted arcs backbone moiety represented by solid lines, namely the part or boron atom, Q ² and skeletal portion connecting the skeleton portion connecting the boron atom to Q ^1, a nitrogen atom one The ring structure is formed together with the part. This is because the compound represented by the above formula (15) has at least four ring structures in the structure, and in the above formula (15), a skeleton portion connecting the boron atom, Q ¹ and the nitrogen atom, and the boron atom It represents that the skeleton part connecting Q ² is included as a part of the ring structure. The ring structure to which X ¹ is bonded is one in which the ring structure skeleton does not contain atoms other than carbon atoms and consists of carbon atoms.
In the above formula (15), the skeleton portions represented by solid lines, that is, the skeleton portions connecting the boron atom, Q ¹ and the nitrogen atom, and the skeleton portions connecting the boron atom and Q ² are the respective skeleton portions. Represents that a pair of atoms connected by a dotted line may be connected by a double bond.

In the above formula (15), the arrow from the nitrogen atom to the boron atom represents that the nitrogen atom is coordinated to the boron atom. Here, coordinating means that the nitrogen atom acts on the boron atom in the same manner as the ligand and has a chemical effect, and is a coordinate bond (covalent bond). Or a coordinate bond may not be formed. Preferably, it is a coordinate bond.

In the above formula (15), Q ¹ and Q ² are the same or different and are a linking group in a skeleton part represented by a solid line, and at least a part thereof forms a ring structure together with a dotted arc part. And it may have a substituent. This indicates that Q ¹ and Q ² are each incorporated as part of the ring structure.
In the above formula (15), X ¹ , X ² , X ³ and X ⁴ are the same or different and each represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure, A plurality of the ring structures may be bonded to each other. ^That, X ^1, X 2, ^{X 3} and when ^{X 4} is a hydrogen atom, the structure of the compound represented by the above formula ^(15), 4 with X ^1, X 2, ^{X 3} and ^{X 4} One ring structure has no substituent, and when any or all of X ¹ , X ² , X ³ and X ⁴ are monovalent substituents, the four rings Any or all of the structures will have substituents. In that case, the number of substituents in one ring structure may be one, or two or more.
In the present specification, the substituent means a group including an organic group containing carbon and a group not containing carbon such as a halogen atom and a hydroxy group.

In the above formula (15), ^{n 1} represents an integer of 2 to 10, ^{Y 1} is a direct bond or ^{n 1} valent connecting group. That is, in the compound represented by the above formula (15), Y ¹ is a direct bond, and two structural parts other than Y ¹ independently form a dotted arc part, ^{Q 1, Q 2, X 1} , X 2, X 3, or attached at any one location in the ^{X 4,} or, ^{Y 1} is ^{n 1} valent connecting group, ^{Y 1} in the formula (15) There are a plurality of structural parts other than those, and they are bonded via Y ¹ which is a linking group.

In the above formula (15), when Y ¹ is a direct bond, the above formula (15) represents a ring structure that forms one of the two other structural portions other than Y ¹ , the dotted arc portion, Q ¹ , Q ² , X ¹ , X ² , X ³ , X ⁴ and the other ring structure forming a dotted arc portion, Q ¹ , Q ² , X ¹ , X ² , X ³ , X ⁴ represents that they are directly bonded to each other. The bonding position is not particularly limited, but the ring to which ^one X ¹ of the structural portion other than Y ¹ is bonded or the ring to which X ² is bonded and the ring to which the other X ¹ is bonded or X It is preferable that the ring to which ² is bonded is directly bonded. More preferably, the ring to which one X ² of the structural portion other than Y ¹ is bonded and the ring to which the other X ² is bonded are directly bonded.
In this case, the structure of the two structural portions other than Y ¹ may be the same or different.

In the above formula (15), Y ¹ is a n ¹ valent connecting group, structural parts other than Y ¹ in the formula (15) there is a plurality, linked via a Y ¹ they are linking group In such a case, the structure in which a plurality of structural parts other than Y ¹ in the formula (15) are bonded via Y ¹ as a linking group is a structure in which structural parts other than Y ¹ are directly bonded. It is more preferable because it is more resistant to oxidation and improves the film-forming property.
Incidentally, ^{Y 1} is the case of ^{n 1} valent connecting group, ^{Y 1} is independently a structural part other than ^{Y 1} present ^{one n,} ring structure to form an arc portion of the dotted ^{line, Q} 1, Q ² , X ¹ , X ² , X ³ , and X ⁴ are bonded at any one position. This is because the structural portion other than Y ¹ is a ring structure that forms a dotted arc portion, Q ¹ , Q ² , X ¹ , X ² , X ³ , X ⁴ may be bonded to Y ¹ at any one position, and there are n ¹ bonding sites with Y ¹ of the structural portion other than Y ^1. It means that it is independent for each of the structural parts other than Y ¹ and all may be the same site, some may be the same site, or all may be different sites. doing. The bonding position is not particularly limited, but all n ¹ structural portions other than Y ¹ are bonded to Y ¹ through a ring to which X ¹ is bonded or a ring to which X ² is bonded. Is preferred. More preferably, all of the structural parts other than Y ¹ present ^one n is that which is bound to Y ¹ in ring X ² is bonded.
The structure of the structural parts other than Y ¹ present ^one n may all be the same, to some may be the same or different all.

When Y ¹ in the formula (15) is n ¹ valent linking group, examples of the linking group, for example, which may have a substituent chain, branched chain or cyclic hydrocarbon group, a substituted Examples thereof include a group containing a hetero element which may have a group, an aryl group which may have a substituent, and a heterocyclic group which may have a substituent. Among these, a group having an aromatic ring such as an aryl group which may have a substituent and a heterocyclic group which may have a substituent is preferable. That is, Y ¹ in the above formula (15) is also a preferred embodiment of the present invention that is a group having an aromatic ring.
Further, Y ¹ may be a linking group having a structure in which a plurality of the linking groups described above are combined.

The chain, branched chain or cyclic hydrocarbon group is preferably a group represented by any of the following formulas (16-1) to (16-8). Among these, the following formulas (16-1) and (16-7) are more preferable.
The group containing the hetero element is preferably a group represented by any of the following formulas (16-9) to (16-13). Among these, the following formulas (16-12) and (16-13) are more preferable.

The aryl group is preferably a group represented by any of the following formulas (16-14) to (16-20). Among these, the following formulas (16-14) and (16-20) are more preferable.

The heterocyclic group is preferably a group represented by any of the following formulas (16-21) to (16-27). Among these, the following formulas (16-23) and (16-24) are more preferable.

Examples of the substituent of the chain, branched or cyclic hydrocarbon group, hetero element-containing group, aryl group, and heterocyclic group include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom halogen atom; A haloalkyl group such as a group, a difluoromethyl group or a trifluoromethyl group; a linear or branched group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group or a tert-butyl group Chain alkyl group; C5-C7 cyclic alkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group; methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, tert-butoxy group, C1-C20 straight chain such as pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group Or a branched alkoxy group; a nitro group; a cyano group; a dialkylamino group having an alkyl group having 1 to 10 carbon atoms such as a methylamino group, an ethylamino group, a dimethylamino group, or a diethylamino group; a diphenylamino group, a carbazolyl group, or the like An acetyl group, a propionyl group, a butyryl group and the like; a vinyl group, a 1-propenyl group, an allyl group, a styryl group and the like, an alkenyl group having 2 to 30 carbon atoms; an ethynyl group, a 1-propynyl group, An alkynyl group having 2 to 30 carbon atoms such as a propargyl group; an aryl group optionally substituted with a halogen atom, an alkyl group, an alkoxy group, an alkenyl group, an alkynyl group; a halogen atom, an alkyl group, an alkoxy group, an alkenyl group, A heterocyclic group optionally substituted by an alkynyl group; N, N-dimethylcarbamo N, N-dialkylcarbamoyl groups such as N group, N, N-diethylcarbamoyl group; dioxaborolanyl group, stannyl group, silyl group, ester group, formyl group, thioether group, epoxy group, isocyanate group, etc. It is done. These groups may be substituted with a halogen atom, a hetero element, an alkyl group, an aromatic ring or the like.
Among these, as the substituent of the linear, branched or cyclic hydrocarbon group in Y ¹ , a group containing a hetero element, an aryl group, or a heterocyclic group, a halogen atom, a straight chain having 1 to 20 carbon atoms A linear or branched alkyl group, a linear or branched alkoxy group having 1 to 20 carbon atoms, an aryl group, a heterocyclic group, or a diarylamino group is preferable. More preferred are an alkyl group, an aryl group, an alkoxy group, and a diarylamino group.
When the chain, branched chain, or cyclic hydrocarbon group in Y ¹ above, a group containing a hetero element, an aryl group, or a heterocyclic group has a substituent, the position and number of the substituent bonded are not particularly limited.

N ¹ in the above formula (15) represents an integer of 2 to 10, preferably an integer of 2 to 6. More preferably, it is an integer of 2-5, More preferably, it is an integer of 2-4, Most preferably, it is 2 or 3 from a soluble viewpoint to a solvent. Most preferably 2. That is, the boron-containing compound represented by the formula (15) is most preferably a dimer.

As Q ¹ and Q ² in the above formula (15), the following formulas (17-1) to (17-8);

The structure represented by is mentioned. In addition, the above formula (17-2) is a structure in which two hydrogen atoms are bonded to a carbon atom and three atoms are further bonded, but the three atoms bonded to the carbon atom other than the hydrogen atom are: All are atoms other than a hydrogen atom. Among the above formulas (17-1) to (17-8), any of (17-1), (17-7), and (17-8) is preferable. More preferably, it is (17-1). That is, it is also one of the preferred embodiments of the present invention that Q ¹ and Q ² are the same or different and represent a linking group having 1 carbon atom.

In the above formula (15), the ring structure formed by the dotted arc and a part of the skeleton part represented by the solid line is a cyclic structure as long as the skeleton of the ring structure to which X ¹ is bonded consists of carbon atoms. If there is no particular limitation.
In the above formula (15), when Y ¹ is a direct bond and n ¹ is 2, examples of the ring to which X ¹ is bonded include a benzene ring, naphthalene ring, anthracene ring, tetracene ring, and pentacene. Ring, triphenylene ring, pyrene ring, fluorene ring, indene ring, thiophene ring, furan ring, pyrrole ring, benzothiophene ring, benzofuran ring, indole ring, dibenzothiophene ring, dibenzofuran ring, carbazole ring, thiazole ring, benzothiazole ring, Examples include oxazole ring, benzoxazole ring, imidazole ring, pyrazole ring, benzimidazole ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, and benzothiadiazole ring. Formula (18-1) to Represented by 18-33).
Among these, those in which the ring structure skeleton is composed of only carbon atoms are preferable, and benzene ring, naphthalene ring, anthracene ring, tetracene ring, pentacene ring, triphenylene ring, pyrene ring, fluorene ring, and indene ring are preferable. More preferred are a benzene ring, a naphthalene ring and a fluorene ring, and still more preferred is a benzene ring.

In the formula (15), when Y ¹ is a direct bond and n ¹ is 2, examples of the ring to which X ² is bonded include an imidazole ring, a benzimidazole ring, a pyridine ring, a pyridazine ring, Examples include a pyrazine ring, a pyrimidine ring, a quinoline ring, an isoquinoline ring, a phenanthridine ring, a quinoxaline ring, a benzothiadiazole ring, a thiazole ring, a benzothiazole ring, an oxazole ring, a benzoxazole ring, an oxadiazole ring, and a thiadiazole ring. These are respectively represented by the following formulas (19-1) to (19-17). Incidentally, * mark in the following formulas (19-1) - (19-17) constitute the ^{ring X 1} is attached and the boron atom to ^{Q 1,} a nitrogen atom in the formula (15) The carbon atom which comprises the skeleton part which connects is couple | bonded with any one of the carbon atoms marked with *. Further, it may be condensed with another ring structure at a position excluding the carbon atom marked with *. Among these, a pyridine ring, a pyrimidine ring, a quinoline ring, and a phenanthridine ring are preferable. More preferred are a pyridine ring, a pyrimidine ring, and a quinoline ring. More preferably, it is a pyridine ring.

In the above formula (15), when Y ¹ is a direct bond and n ¹ is 2, the ring to which X ³ is bonded and the ring to which X ⁴ is bonded are represented by the above formula (18 -1) to (18-33). Among these, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable. More preferably, it is a benzene ring.

In the above formula (15), X ¹ , X ² , X ³ and X ⁴ are the same or different and each represents a hydrogen atom or a monovalent substituent serving as a substituent of a ring structure. The monovalent substituent is not particularly limited, and examples of X ¹ , X ² , X ³ and X ⁴ include a hydrogen atom, an aryl group which may have a substituent, a heterocyclic group, and an alkyl group. , Alkenyl group, alkynyl group, alkoxy group, aryloxy group, arylalkoxy group, silyl group, hydroxy group, amino group, halogen atom, carboxyl group, thiol group, epoxy group, acyl group, substituent Good oligoaryl group, monovalent oligo heterocyclic group, alkylthio group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, azo group, stannyl group, phosphino group, silyloxy group, substituent May have an aryloxycarbonyl group, an alkoxycarbonyl group which may have a substituent, and a substituent. A good carbamoyl group, an arylcarbonyl group which may have a substituent, an alkylcarbonyl group which may have a substituent, an arylsulfonyl group which may have a substituent, and a substituent. Alkylsulfonyl group, optionally substituted arylsulfinyl group, optionally substituted alkylsulfinyl group, formyl group, cyano group, nitro group, arylsulfonyloxy group, alkylsulfonyloxy group Alkyl sulfonate groups such as methane sulfonate group, ethane sulfonate group and trifluoromethane sulfonate group; aryl sulfonate groups such as benzene sulfonate group and p-toluene sulfonate group; aryl alkyl sulfonate groups such as benzyl sulfonate group, boryl group and sulfonium methyl group , Phos Methyl group, phosphonate methyl group, an aryl sulfonate group, an aldehyde group, acetonitrile group, or the like.

Examples of the substituent in X ¹ , X ² , X ³ and X ⁴ include a fluorine atom, a chlorine atom, a bromine atom, a halogen atom of iodine atom; a methyl chloride group, a methyl bromide group, a methyl iodide group, a fluoromethyl group Haloalkyl groups such as difluoromethyl group and trifluoromethyl group; straight chain having 1 to 20 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group and tert-butyl group Linear or branched alkyl group; C5-C7 cyclic alkyl group such as cyclopentyl group, cyclohexyl group, cycloheptyl group; methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, tert -Carbon number of butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, etc. A linear or branched alkoxy group of -20; a hydroxy group; a thiol group; a nitro group; a cyano group; an amino group; an azo group; a carbon number of 1 such as a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group Mono- or dialkylamino group having an alkyl group of ˜40; amino group such as diphenylamino group, carbazolyl group; acyl group such as acetyl group, propionyl group, butyryl group; vinyl group, 1-propenyl group, allyl group, butenyl group An alkynyl group having 2 to 20 carbon atoms such as styryl group; an alkynyl group having 2 to 20 carbon atoms such as ethynyl group, 1-propynyl group, propargyl group and phenylacetylin; alkenyloxy group such as vinyloxy group and allyloxy group; Alkynyloxy groups such as ethynyloxy group and phenylacetyloxy group; phenoxy group, Aryloxy groups such as ftoxy group, biphenyloxy group, pyrenyloxy group; perfluoro groups such as trifluoromethyl group, trifluoromethoxy group, pentafluoroethoxy group, perfluorophenyl group, and further long-chain perfluoro groups; diphenylboryl Groups, dimesitylboryl groups, boryl groups such as bis (perfluorophenyl) boryl groups; carbonyl groups such as acetyl groups and benzoyl groups; carbonyloxy groups such as acetoxy groups and benzoyloxy groups; methoxycarbonyl groups, ethoxycarbonyl groups, phenoxycarbonyls Alkoxycarbonyl groups such as groups; sulfinyl groups such as methylsulfinyl groups and phenylsulfinyl groups; alkylsulfonyloxy groups; arylsulfonyloxy groups; phosphino groups; trimethylsilyl groups, triisopropyl groups Silyl group such as ryl group, dimethyl-tert-butylsilyl group, trimethoxysilyl group, triphenylsilyl group; silyloxy group; stannyl group; phenyl group optionally substituted by halogen atom, alkyl group, alkoxy group, etc., 2 , 6-Xylyl group, mesityl group, duryl group, biphenyl group, terphenyl group, naphthyl group, anthryl group, pyrenyl group, toluyl group, anisyl group, fluorophenyl group, diphenylaminophenyl group, dimethylaminophenyl group, diethylaminophenyl Group, aryl group such as phenanthrenyl group; thienyl group, furyl group, silacyclopentadienyl group, oxazolyl group, oxadiazolyl group, thiazolyl group, thiadiazolyl group, acridinyl group, quinolyl group, quinoxaloyl group, phenanthrolyl group, benzothienyl group Group, benzothiazolyl group, indolyl group, carbazolyl group, pyridyl group, pyrrolyl group, benzoxazolyl group, pyrimidyl group, imidazolyl group and the like; carboxyl group; carboxylate ester; epoxy group; isocyano group; cyanate group Isocyanate group; thiocyanate group; isothiocyanate group; carbamoyl group; N, N-dialkylcarbamoyl group such as N, N-dimethylcarbamoyl group, N, N-diethylcarbamoyl group; formyl group; nitroso group; formyloxy group; Is mentioned. In addition, these groups may be substituted with a halogen atom, an alkyl group, an aryl group, or the like, and these groups may be bonded to each other at any place to form a ring.

Among these, X ¹ , X ² , X ³ and X ⁴ are each a hydrogen atom; a halogen atom, a carboxyl group, a hydroxy group, a thiol group, an epoxy group, an amino group, an azo group, an acyl group, an allyl group, or a nitro group. , Reactive groups such as alkoxycarbonyl group, formyl group, cyano group, silyl group, stannyl group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, alkylsulfonyloxy group; Or a branched alkyl group; a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched alkoxy group having 1 to 8 carbon atoms, an aryl group, an alkenyl group having 2 to 8 carbon atoms A linear or branched alkyl group having 1 to 20 carbon atoms substituted with an alkynyl group having 2 to 8 carbon atoms or the reactive group; Or branched alkoxy group; linear or branched alkyl group having 1 to 8 carbon atoms, linear or branched alkoxy group having 1 to 8 carbon atoms, aryl group, alkenyl having 2 to 8 carbon atoms Group, a C2-C8 alkynyl group or a reactive group substituted with a C1-C20 linear or branched alkoxy group; an aryl group; a C1-C8 linear or branched group Substituted with a chain alkyl group, a linear or branched alkoxy group having 1 to 8 carbon atoms, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or the reactive group , Aryl group; oligoaryl group; linear or branched alkyl group having 1 to 8 carbon atoms, linear or branched alkoxy group having 1 to 8 carbon atoms, aryl group, alkenyl having 2 to 8 carbon atoms A group having 2 to 8 carbon atoms Oligoaryl group substituted by a quinyl group or the reactive group; a monovalent heterocyclic group; a linear or branched alkyl group having 1 to 8 carbon atoms; a linear or branched group having 1 to 8 carbon atoms A monovalent heterocyclic group substituted by a chain alkoxy group, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or the reactive group; a monovalent oligo heterocyclic group; C1-C8 linear or branched alkyl group, C1-C8 linear or branched alkoxy group, aryl group, C2-C8 alkenyl group, C2-C8 Monovalent oligo heterocyclic group substituted with an alkynyl group or the reactive group; alkylthio group; aryloxy group; arylthio group; arylalkyl group; arylalkoxy group; arylalkylthio group; alkenyl group; The linear young Or a branched alkyl group, a linear or branched alkoxy group having 1 to 8 carbon atoms, an aryl group, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or the reactive group. Substituted alkenyl group; alkynyl group; linear or branched alkyl group having 1 to 8 carbon atoms, linear or branched alkoxy group having 1 to 8 carbon atoms, aryl group, 2 to 8 carbon atoms And an alkynyl group substituted with an alkynyl group having 2 to 8 carbon atoms or the reactive group.
More preferably, a hydrogen atom, a bromine atom, an iodine atom, an amino group, a boryl group, an alkynyl group, an alkenyl group, a formyl group, a silyl group, a stannyl group, a phosphino group, an aryl group substituted with the reactive group, the reaction Oligoaryl group, monovalent heterocyclic group, monovalent heterocyclic group substituted with the reactive group, monovalent oligoheterocyclic group substituted with the reactive group, alkenyl group Or an alkenyl group substituted with the reactive group, an alkynyl group, or an alkynyl group substituted with the reactive group. Among these, X ¹ and X ² are more preferably functional groups that are resistant to reduction, such as hydrogen atoms, alkyl groups, aryl groups, nitrogen-containing heteroaromatic groups, alkenyl groups, alkoxy groups, aryloxy groups, and silyl groups. Particularly preferred are a hydrogen atom, an aryl group, and a nitrogen-containing heteroaromatic group. X ³ and X ⁴ are more preferably a functional group resistant to oxidation such as a hydrogen atom, a carbazolyl group, a triphenylamino group, a thienyl group, a furanyl group, an alkyl group, an aryl group, and an indolyl group. Particularly preferred are a hydrogen atom, a carbazolyl group, a triphenylamino group, and a thienyl group. Thus, assuming that X ¹ and X ² have functional groups that are resistant to reduction and X ³ and X ⁴ have functional groups that are resistant to oxidation, the boron-containing compound as a whole is a compound that is further resistant to reduction and oxidation. It is considered that.
In the above formula (15), when X ¹ , X ² , X ³ and X ⁴ are monovalent substituents, X ¹ , X ² , X ³ and X ⁴ are bonded to or bonded to the ring structure. The number is not particularly limited.

In the above formula (15), ^{Y 1} is ^{n 1} valent connecting group, when ^{n 1} is 2 to 10, as the ^{ring X 1} is attached, in the above formula (15), ^{Y 1} is It is a direct bond, and when n ¹ is 2, it is the same as the ring to which X ¹ is bonded. Among these rings, a benzene ring, a naphthalene ring, and a benzothiophene ring are preferable. More preferably, it is a benzene ring.

In the above formula (15), ^{Y 1} is ^{n 1} valent connecting group, when ^{n 1} is 2-10, ring ^{ring X 2} is bonded, is ^{X 3} are attached, and, X ^{As the} ring to which ⁴ is bonded, in the above formula (15), Y ¹ is a direct bond, and when n ¹ is 2, a ring to which X ² is bonded, and X ³ is bonded. The ring is the same as the ring mentioned as the ring to which X ⁴ is bonded, and the preferred structure is also the same.

That is, a ^{Y 1} is a direct bond in formula (15), when ^{n 1} is 2, and, ^{Y 1} is ^{n 1} valent linking group, either when ^{n 1} is 2 to 10 In this case, the boron-containing compound represented by the above formula (15) is represented by the following formula (20);

(In the formula, an arrow from a nitrogen atom to a boron atom, X ¹ , X ² , X ³ , X ⁴ , n ¹ and Y ¹ are the same as those in the formula (15)). This is also one of the preferred embodiments of the present invention.

The boron-containing compound represented by the above formula (15) can be synthesized by using various commonly used reactions such as a Suzuki coupling reaction. Further, it can be synthesized by the method described in Journal of the American Chemical Society, 2009, Vol. 131, No. 40, pages 14549-14559.
An example of a synthesis scheme of the boron-containing compound represented by the above formula (15) is represented by the following reaction formula. The following reaction formula (I) represents an example of a synthesis scheme of the boron-containing compound represented by the above formula (15), in which Y ¹ is a direct bond and n ¹ is 2, and the following reaction formula ( II) is a boron-containing compound represented by the above formula (15), Y ¹ is n ¹ valent connecting group, n ¹ represents the example of a synthetic scheme as 2-10. However, the manufacturing method of the boron containing compound represented by the said Formula (15) is not restrict | limited to this.
In the following scheme, the compound of (a) as a raw material is described in, for example, Journal of Organic Chemistry, 2010, Vol. 75, No. 24, pages 8709-8712. It can be synthesized by a technique. Moreover, the compound of (b) used as a raw material is compoundable by the boronation reaction represented by following Reaction formula (III) with respect to the compound of (a).

The boron-containing compound represented by the above formula (15) can be uniformly formed by coating and has a low HOMO and LUMO level, and therefore is preferably used as a material for the organic electroluminescence device of the present invention. It can be done.

The organic electroluminescent element of the present invention is superior in luminous efficiency and luminescent lifetime as compared with conventional organic-inorganic hybrid organic electroluminescent elements by using a metal complex as a light emitting layer host. It can be suitably used as a material.
Such a display device formed using the organic electroluminescent element of the present invention is also one aspect of the present invention. Furthermore, a lighting device formed using the organic electroluminescent element of the present invention is also one aspect of the present invention.

The organic electroluminescent element of the present invention has the above-described configuration, and is excellent in light emission characteristics such as light emission efficiency and light emission lifetime as compared with conventional organic / inorganic hybrid organic electroluminescent elements. Organic-inorganic hybrid type organic electroluminescent device is manufactured such that the necessity of strictly sealing each layer is reduced like an organic electroluminescent device in which each layer constituting the organic electroluminescent device is composed of organic matter. The organic electroluminescent element of the present invention having such advantages and excellent light emission characteristics can be suitably used for materials for display devices and lighting devices.

4 is a graph showing voltage-luminance characteristics of organic electroluminescent elements fabricated in Example 1 and Comparative Example 1. 3 is a graph showing current density-current efficiency characteristics of organic electroluminescent elements fabricated in Example 1 and Comparative Example 1. 4 is a graph showing a change in relative luminance with time of the organic electroluminescent elements produced in Example 1 and Comparative Example 1. It is a graph which shows the voltage-luminance characteristic of the organic electroluminescent element produced in Example 2 and Comparative Example 2. FIG. It is a graph which shows the current density-current efficiency characteristic of the organic electroluminescent element produced in Example 2 and Comparative Example 2. It is a graph which shows the time-dependent change of the relative luminance of the organic electroluminescent element produced in Example 2 and Comparative Example 2.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

In the following examples, the average thickness of each layer constituting the organic electroluminescent element was measured using a stylus type step meter (product name “Alpha Step IQ”, manufactured by KLA Tencor).

(Synthesis Example 1)
(Synthesis of 2,7-bis (3-dibenzoborolyl-4-pyridylphenyl) -9,9'-spirofluorene)
In a 100 mL two-necked eggplant flask, 2- (dibenzoborolylphenyl) -5-bromopyridine (2.6 g, 6.5 mmol), 2,7-bis (4,4,5,5-tetramethyl-1,3). , 2-dioxaborolanyl) -9,9′-spirofluorene (1.5 g, 2.7 mmol), Pd (P ^t Bu ₃ ) ₂ (170 mg, 0.32 mmol). The flask was placed under a nitrogen atmosphere, THF (65 mL) was added, and the mixture was stirred.
To this was added 2M aqueous tripotassium phosphate solution (11 mL, 22 mmol), and the mixture was heated and stirred while refluxing at 70 ° C. After 12 hours, the mixture was cooled to room temperature, the reaction solution was transferred to a separatory funnel, water was added, and the mixture was extracted with ethyl acetate. The organic layer was washed with 3N hydrochloric acid, water and saturated brine, and then dried over magnesium sulfate. The filtered filtrate is concentrated, and the resulting solid is washed with methanol to give 2,7-bis (3-dibenzoborolyl-4-pyridylphenyl) -9,9′-spirofluorene (boron-containing compound 1). Obtained in 47% yield (1.2 g, 1.3 mmol).
The physical property values were as follows.
¹ H-NMR (CDCl ₃ ): δ 6.67 (d, J = 7.6 Hz, 2H), 6.75 (d, J = 1.2 Hz, 2H), 6.82 (d, J = 7.2 Hz) , 4H), 6.97 (dt, J = 7.2, 1.2 Hz, 4H), 7.09 (dt, J = 7.2, 0.8 Hz, 2H), 7.24-7.40 ( m, 14H), 7.74-7.77 (m, 6H), 7.84-7.95 (m, 10H)
Further, the reaction of Synthesis Example 1 is represented by the following reaction formula.

(Production of organic electroluminescence device)
Example 1
[1] A commercially available transparent glass substrate with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode (first electrode) of the substrate used was patterned to a width of 2 mm. This substrate was subjected to ultrasonic cleaning in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This substrate was taken out from isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.
[2] This substrate was fixed to a substrate holder of a Miratron sputtering apparatus having a zinc metal target. After reducing the pressure to about 1 × 10 ⁻⁴ Pa, sputtering was performed in a state where argon and oxygen were introduced to form a zinc oxide layer having a thickness of about 2 nm. At this time, a metal mask was used in combination so that a portion of the ITO electrode was not deposited with zinc oxide for electrode extraction.
[3] A mixed solution of magnesium acetate in 1% water-ethanol (1: 3 by volume) was prepared. The substrate prepared in step [2] was washed again in the same manner as in step [1]. The cleaned substrate with a zinc oxide thin film was set on a spin coater. A magnesium acetate solution was dropped on the substrate and rotated at 1300 rpm for 60 seconds. This was fired in the air on a hot plate set at 400 ° C. for 2 hours to form a zinc oxide / magnesium oxide layer (first metal oxide layer).
[4] A 0.2% tetrahydrofuran solution of boron-containing compound 1 was prepared. The substrate with the zinc oxide / magnesium oxide thin film (layer) prepared in the step [3] was set on a spin coater. A boron-containing compound 1 solution was dropped on this substrate and rotated at 2000 rpm for 30 seconds to form a buffer layer made of a boron-containing organic compound. The average thickness of the buffer layer was 5 nm.
[5] The substrate formed up to the layer of the boron-containing organic compound was fixed to a substrate holder of a vacuum deposition apparatus. Bis (10-hydroxybenzo [h] quinolinato) beryllium (Bebq ₂ ), iridium tris (1-phenylisoquinoline) (Ir (piq) ₃ ), N, N′-di (1-naphthyl) -N, N′- Diphenyl-1,1′-biphenyl-4,4′-diamine (α-NPD) was put in an alumina crucible and set in a vapor deposition source. The inside of the vacuum evaporation apparatus was depressurized to about 1 × 10 ⁻⁵ Pa, and 35 nm was co-evaporated using Bebq ₂ as a host and Ir (piq) ₃ as a dopant to form a light emitting layer. At this time, the doping concentration was such that Ir (piq) ₃ was 6% by weight with respect to the entire light emitting layer. Next, α-NPD was deposited to 60 nm to form a hole transport layer. Next, after once purging with nitrogen, molybdenum trioxide and gold were put in an alumina crucible and set in a vapor deposition source. The inside of the vacuum deposition apparatus was depressurized to about 1 × 10 ⁻⁵ Pa, and molybdenum trioxide (second metal oxide layer) was deposited to a thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to have a film thickness of 50 nm, and the organic electroluminescent element 1 was produced. When the second electrode was deposited, a deposition mask made of stainless steel was used so that the deposition surface was a band with a width of 2 mm. That is, the light emitting area of the produced organic electroluminescent element was 4 mm ² .

(Comparative Example 1)
Organic electroluminescence device in the same manner as in Example 1, except that 4,4′-bis [9-dicarbazolyl] -2,2′-biphenyl (CBP) was used as the host in place of Bebq ₂ in Step [5] 2 was produced.

(Example 2)
[1] A commercially available transparent glass substrate with an ITO electrode layer having an average thickness of 0.7 mm was prepared. At this time, the ITO electrode (first electrode) of the substrate used was patterned to a width of 2 mm. This substrate was subjected to ultrasonic cleaning in acetone and isopropanol for 10 minutes, and then boiled in isopropanol for 5 minutes. This substrate was taken out from isopropanol, dried by nitrogen blowing, and UV ozone cleaning was performed for 20 minutes.
[2] This substrate was fixed to a substrate holder of a Miratron sputtering apparatus having a zinc metal target. After reducing the pressure to about 1 × 10 ⁻⁴ Pa, sputtering was performed in a state where argon and oxygen were introduced to form a zinc oxide layer having a thickness of about 2 nm. At this time, a metal mask was used in combination so that a portion of the ITO electrode was not deposited with zinc oxide for electrode extraction. This was baked for 1 hour on a hot plate set at 400 ° C. in the atmosphere to form a zinc oxide layer (first metal oxide layer).
[3] 1% of boron-containing compound 1, 0.01% of (4- (1,3-dimethyl-2,3-dihydro-1H-benzimidazol-2-yl) phenyl) dimethylamine (N-DMBI) A 1,2-dichloroethane mixed solution was prepared. The substrate with the zinc oxide thin film (layer) prepared in step [2] was set on a spin coater. A boron-containing compound 1 and N-DMBI mixed solution was dropped on this substrate and rotated at 2000 rpm for 30 seconds to form a buffer layer containing a boron-containing organic compound. Further, this was annealed for 1 hour on a hot plate set at 100 ° C. in a nitrogen atmosphere. The average thickness of the buffer layer was 60 nm.
[4] The substrate formed up to the layer of the boron-containing compound was fixed to a substrate holder of a vacuum deposition apparatus. Bis [2- (2′-hydroxyphenyl) pyridine] beryllium (Bep ₂ ), tris [3-methyl-2-phenylpyridine] iridium (III) (Ir (mpy) ₃ ), N, N′-di (1 -Naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine (α-NPD) was placed in an alumina crucible and set in a vapor deposition source. The inside of the vacuum evaporation apparatus was depressurized to about 1 × 10 ⁻⁵ Pa, and 35 nm was co-evaporated with Bepp ₂ as a host and (Ir (mpy) ₃ ) as a dopant to form a light emitting layer. At this time, the doping concentration was set so that (Ir (mpy) ₃ ) was 6% by weight with respect to the entire light emitting layer. Next, α-NPD was deposited to 60 nm to form a hole transport layer. Next, after once purging with nitrogen, molybdenum trioxide and gold were put in an alumina crucible and set in a vapor deposition source. The inside of the vacuum deposition apparatus was depressurized to about 1 × 10 ⁻⁵ Pa, and molybdenum trioxide (second metal oxide layer) was deposited to a thickness of 10 nm. Next, gold (second electrode) was vapor-deposited so as to have a film thickness of 50 nm, and the organic electroluminescent element 3 was produced. When the second electrode was deposited, a deposition mask made of stainless steel was used so that the deposition surface was a band with a width of 2 mm. That is, the light emitting area of the produced organic electroluminescent element was 4 mm ² .

(Comparative Example 2)
Organic electroluminescent element 4 was produced in the same manner as in Example 2 except that CBP was used as the host in place of Bepp ₂ in step [4].

(Measurement of light emission characteristics of organic electroluminescence device)
Voltage application to the device and current measurement were performed using a “2400 type source meter” manufactured by Keithley. Luminance was measured with “LS-100” manufactured by Konica Minolta.
FIG. 1 shows the voltage-luminance characteristics and FIG. 2 shows the current density-current efficiency characteristics of the organic electroluminescence devices produced in Example 1 and Comparative Example 1 when a DC voltage of 0 V to 14 V is applied in an argon atmosphere. Shown in It was found that the device manufactured in Example 1 had excellent characteristics with high luminance and current efficiency as compared with the device manufactured in Comparative Example 1. Further, FIG. 3 shows a change in relative luminance when the organic electroluminescent elements produced in Example 1 and Comparative Example 1 were applied with a constant direct current of 100 cd / m ² initially in an argon atmosphere. The device manufactured in Example 1 was found to have a long lifetime because the decrease in luminance was suppressed compared to the device manufactured in Comparative Example 1.
Similarly, FIG. 4 shows the voltage-luminance characteristics of the organic electroluminescent elements produced in Example 2 and Comparative Example 2 when a DC voltage of 0 V to 18 V is applied in an argon atmosphere, and the current density-current efficiency characteristics. Is shown in FIG. It was found that the device manufactured in Example 2 had excellent characteristics with high luminance and current efficiency as compared with the device manufactured in Comparative Example 2. FIG. 6 shows a change in relative luminance when the organic electroluminescent elements produced in Example 2 and Comparative Example 2 were applied with a constant direct current of 100 cd / m ² in an argon atmosphere. The device manufactured in Example 2 was found to have a long lifetime because the decrease in luminance was suppressed compared to the device manufactured in Comparative Example 2.

Claims (5)

An organic electroluminescent device having a structure in which a plurality of layers are laminated,
The organic electroluminescence device includes a first metal oxide layer, a low molecular compound layer including a light emitting layer, and a second metal oxide layer in this order between the first electrode and the second electrode. Have
The organic light emitting device, wherein the light emitting layer contains at least one metal complex that functions as a host. The organic electroluminescent element has a buffer layer between the first metal oxide layer and the low molecular compound layer including the light emitting layer,
The organic electroluminescence device according to claim 1, wherein the buffer layer is a layer having an average thickness of 5 to 100 nm formed by applying a solution containing an organic compound. The organic light emitting device according to claim 1, wherein the light emitting layer contains a phosphorescent light emitting material. It forms using the organic electroluminescent element in any one of Claims 1-3, The display apparatus characterized by the above-mentioned. An illuminating device formed using the organic electroluminescent element according to claim 1.

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