JP6705148B2 - π-conjugated compound, organic electroluminescent element material, light emitting material, light emitting thin film, organic electroluminescent element, display device and lighting device - Google Patents

Description

The present invention relates to a π-conjugated compound, an organic electroluminescence element material, a light emitting material, a light emitting thin film, an organic electroluminescence element, a display device and a lighting device.

An organic EL element (also referred to as an “organic electroluminescent element”) that uses electroluminescence (hereinafter, abbreviated as “EL”) of an organic material has already been put into practical use as a new light emitting system capable of planar light emission. It is a technology that is being used. Organic EL devices have been applied not only to electronic displays but also to lighting devices in recent years, and their development is expected.

There are two types of light emission methods of organic EL devices: "phosphorescence emission" that emits light when returning from the triplet excited state to the ground state and "fluorescence emission" that emits light when returning from the singlet excited state to the ground state. There is a street.

When an electric field is applied to the organic EL element, holes and electrons are injected from the anode and cathode, respectively, and recombine in the light emitting layer to generate excitons. At this time, since singlet excitons and triplet excitons are generated at a ratio of 25%:75%, phosphorescence emission using triplet excitons has theoretically higher internal quantum than fluorescence emission. It is known that efficiency can be obtained. However, in order to actually obtain high quantum efficiency in the phosphorescence emission method, it is necessary to use a complex using a rare metal such as iridium or platinum as the central metal, and in the future, the reserves of rare metals and the metal itself There is concern that price will become a big issue in the industry.

On the other hand, various developments have been made to improve the luminous efficiency of the fluorescent light emitting type as well, and a new movement has recently been made. For example, in Patent Document 1, a phenomenon in which singlet excitons are generated by collision of two triplet excitons (Triplet-Triple Annihilation: hereinafter, abbreviated as "TTA" as appropriate. In addition, Triplet-Triplet Fusion: "TTF." Also referred to as "."), a technique for efficiently causing TTA to increase the efficiency of the fluorescent element is disclosed. By this technology, the emission efficiency of the fluorescent light emitting material is improved to 2 to 3 times that of the conventional fluorescent light emitting material, but the theoretical singlet exciton generation efficiency in TTA is only about 40%, and therefore the phosphorescent light emission is still possible. However, it has a problem of higher luminous efficiency.

Further, in recent years, a phenomenon utilizing a phenomenon (reverse intersystem crossing: hereinafter appropriately abbreviated as “RISC”) from triplet excitons to singlet excitons (heat activated delayed fluorescence (“ Also referred to as "thermally excited delayed fluorescence": Thermally Activated Delayed Fluorescence: hereinafter, abbreviated as "TADF" as appropriate), and the possibility of use in organic EL devices has been reported (for example, (Patent Document 2, Non-Patent Document 1, Non-Patent Document 2) By using the delayed fluorescence by the TADF mechanism, theoretically 100% internal quantum efficiency equivalent to phosphorescence emission is obtained even in fluorescence emission by electric field excitation. Is possible.

In order to develop the TADF phenomenon, it is necessary that 75% of the triplet excitons are inversely crossed to singlet excitons caused by electric field excitation at room temperature or the temperature of the light emitting layer in the light emitting device. Further, the singlet excitons generated by the inverse intersystem crossing emit fluorescence similarly to the 25% singlet excitons generated by the direct excitation, whereby 100% internal quantum efficiency is theoretically possible. In order for this reverse intersystem crossing to occur, it is required that the absolute value (ΔE _ST ) of the difference between the lowest excited singlet energy level (S1) and the lowest triplet excited energy level (T1) is small.

Further, it is known that when a light emitting layer composed of a host material and a light emitting material contains a material exhibiting TADF property as a third component (assist dopant material) in the light emitting layer, it is effective in exhibiting high light emitting efficiency ( Non-Patent Document 3). By generating 25% singlet excitons and 75% triplet excitons on the assisting dopant material by electric field excitation, the triplet excitons generate singlet excitons accompanied by reciprocal intersystem crossing (RISC). can do. The energy of the singlet excitons undergoes fluorescence resonance energy transfer (hereinafter, abbreviated as “FRET” as appropriate) to the light emitting material, and the light emitting material can emit light by the energy transferred. .. Therefore, theoretically 100% of exciton energy can be used to cause the light emitting material to emit light, and high light emitting efficiency is exhibited.

For example, in order to express the TADF phenomenon, it is effective to reduce the Delta] E _ST organic compound; in order to reduce the Delta] E _ST is the highest occupied molecular orbital of the molecule (HOMO) the lowest unoccupied molecular orbital ( It is effective to localize (clearly separate) LUMO) without mixing them.

1 and 2 are schematic diagrams showing energy diagrams of a compound expressing the TADF phenomenon (TADF compound) and a general fluorescent material. For example, in 2CzPN having the structure shown in FIG. 1, HOMO is localized at the carbazolyl groups at the 1st and 2nd positions and LUMO is localized at the 4th and 5th cyano groups on the benzene ring. Therefore, it is possible to separate the HOMO and LUMO of 2CzPN, ΔE _ST express TADF phenomenon extremely small. On the other hand, in 2CzXy (Fig. 2) in which the cyano groups at the 4- and 5-positions of 2CzPN are replaced with methyl groups, the structures are similar, but because HOMO and LUMO seen in 2CzPN cannot be clearly separated, ΔE _ST cannot be reduced, and the TADF phenomenon cannot be expressed.

In the prior art, in order to clearly separate HOMO and LUMO, a method using a strong electron-donating group or electron-withdrawing group is known. However, the use of a strong electron-donating group or electron-withdrawing group forms an excited state having a strong intramolecular charge transfer (CT) property, which causes a long wavelength absorption spectrum or emission spectrum. Is difficult to control. On the contrary, if the electron donating property or the electron withdrawing property is weakened to control the emission wavelength, the TADF phenomenon will be impaired. Therefore, a new method of expressing the TADF phenomenon while controlling the emission wavelength is desired.

International Publication No. 2010/134350 JP, 2013-116975, A

H. Uoyama, et al. , Nature, 2012, 492, 234-238. Q. Zhang et al. , Nature, Photonics, 2014, 8, 326-332. H. Nakanotani, et al. , Nature Communication, 2014, 5, 4016-4022.

The present invention has been made in view of the above problems and circumstances, and a problem to be solved is to provide a new π-conjugated compound that can improve the light emission efficiency of an organic electroluminescence device, for example. Another object of the present invention is to provide an organic electroluminescence element material, a light-emitting material, a light-emitting thin film, an organic electroluminescence element, and a display device and a lighting device including the organic electroluminescence element, which use the π-conjugated compound. ..

The present inventors, in order to solve the above problems, the results of investigation of the cause or the like of the above problems, replacing the electron withdrawing group A ¹ having an aromatic heterocyclic 5-membered ring skeleton to a benzene ring, further electron-withdrawing group A ¹ has been newly conceived and a π-conjugated compound having an electron-donating group D adjacent to at least ^one of the para-positions has been found, and it has been found that the use of this compound in an organic electroluminescence device can improve the luminous efficiency. I arrived.

（一般式（１）中、
Ａ^１は、置換されていてもよい芳香族複素５員環骨格を有する電子吸引性基を表し、
Ｄ^１及びＤ^２は、各々独立に、電子供与性基を表し、
Ｚ^１〜Ｚ^３は、各々独立に、水素原子、重水素原子、電子供与性基又は電子吸引性基を表し、
前記Ｄ^１及びＤ^２及びＺ^１〜Ｚ^３で表される前記電子供与性基は、電子供与性基で置換されたアリール基、置換されていてもよい電子供与性の複素環基、置換されていてもよいアミノ基、及びアルキル基からなる群より選ばれる基であり、
前記Ｚ^１〜Ｚ^３で表される前記電子吸引性基は、フッ素原子、フッ素原子で置換されたアルキル基、置換されていてもよいカルボニル基、置換されていてもよいスルホニル基、置換されていてもよいホスフィンオキサイド基、置換されていてもよいボリル基、電子吸引性基で置換されていてもよいアリール基、及び置換されていてもよい電子吸引性の複素環基からなる群より選ばれる基である。）
［２］ 前記一般式（１）において、Ｚ^１は前記電子供与性基を表す、［１］に記載のπ共役系化合物。
［３］ 前記一般式（１）において、Ｚ^１は前記電子供与性基を表し、Ｚ^２とＺ^３は水素原子を表す、［１］または［２］に記載のπ共役系化合物。
［４］ 前記芳香族複素５員環骨格は、窒素原子を含む、［１］〜［３］のいずれか一項に記載のπ共役系化合物。
［５］ 最低励起一重項準位と最低励起三重項準位とのエネルギー差の絶対値ΔＥ_ＳＴが０．５０ｅＶ以下である、［１］〜［４］のいずれか一項に記載のπ共役系化合物。 That is, the above-mentioned subject concerning the present invention is solved by the following means.
[1] A π-conjugated compound having a structure represented by the following general formula (1).

(In the general formula (1),
A ¹ represents an electron-withdrawing group having an optionally substituted aromatic hetero 5-membered ring skeleton,
D ¹ and D ² each independently represent an electron-donating group,
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group,
The electron-donating group represented by D ¹ and D ² and Z ^{1 to} Z ³ is an aryl group substituted with an electron-donating group, an electron-donating heterocyclic group which may be substituted, or a substituent. An optionally substituted amino group, and a group selected from the group consisting of an alkyl group,
The electron withdrawing group represented by Z ^{1 to} Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an unsubstituted group. Selected from the group consisting of an optionally substituted phosphine oxide group, an optionally substituted boryl group, an optionally substituted aryl group with an electron withdrawing group, and an optionally substituted electron withdrawing heterocyclic group. It is a base. )
[2] The π-conjugated compound according to [1], wherein in the general formula (1), Z ¹ represents the electron-donating group.
[3] The π-conjugated compound according to [1] or [2], wherein in the general formula (1), Z ¹ represents the electron donating group, and Z ² and Z ³ represent a hydrogen atom.
[4] The π-conjugated compound according to any one of [1] to [3], wherein the aromatic hetero 5-membered ring skeleton contains a nitrogen atom.
[5] an absolute value of the lowest Delta] E _ST of the energy difference between the excited singlet state and the lowest excited triplet level is below 0.50eV, [1] ~ π-conjugated according to any one of [4] Compounds.

[6] An organic electroluminescence device material containing the π-conjugated compound according to any one of [1] to [5].
[7] A luminescent material containing the π-conjugated compound according to any one of [1] to [5], wherein the π-conjugated compound emits fluorescence.
[8] The luminescent material according to [7], wherein the π-conjugated compound emits delayed fluorescence.
[9] A luminescent thin film containing the π-conjugated compound according to any one of [1] to [5].
[10] The luminescent thin film according to [9], wherein the π-conjugated compound emits delayed fluorescence.
[11] An anode, a cathode, and a light emitting layer provided between the anode and the cathode,
At least one layer of the said light emitting layer is an organic electroluminescent element containing the (pi) conjugated system compound as described in any one of [1]-[5].
[12] The organic electroluminescent device according to [11], in which the π-conjugated compound produces excitons.
[13] The organic electroluminescence device according to [11] or [12], wherein the π-conjugated compound emits fluorescence.
[14] The organic electroluminescence device according to [13], wherein the π-conjugated compound emits delayed fluorescence.
[15] The organic electroluminescence device according to any one of [11] to [14], wherein the light emitting layer contains the π-conjugated compound and a host compound.
[16] The organic electroluminescence according to any one of [11] to [15], wherein the light emitting layer contains the π-conjugated compound and at least one of a fluorescent light emitting compound and a phosphorescent light emitting compound. element.
[17] The emitting layer contains the π-conjugated compound, at least one of a fluorescent emitting compound and a phosphorescent emitting compound, and a host compound, according to any one of [11] to [15]. Organic electroluminescent device.

（一般式（Ｉ）中、
Ｘ_１０１は、ＮＲ_１０１、酸素原子、硫黄原子、スルフィニル基、スルホニル基、ＣＲ_１０２Ｒ_１０３又はＳｉＲ_１０４Ｒ_１０５を表し、
ｙ_１〜ｙ_８は、各々独立に、ＣＲ_１０６又は窒素原子を表し、
Ｒ_１０１〜Ｒ_１０６は、各々独立に、水素原子又は置換基を表し、互いに結合して環を形成してもよく、
Ａｒ_１０１及びＡｒ_１０２は、各々独立に、置換されていてもよいアリール基、又は置換されていてもよいヘテロアリール基を表し、
ｎ１０１及びｎ１０２は、各々０〜４の整数を表す。
ただし、Ｒ_１０１が水素原子の場合は、ｎ１０１は１〜４の整数を表す。）
［１９］ 前記一般式（Ｉ）で表される構造を有するホスト化合物が、下記一般式（II）で表される構造を有する、［１８］に記載の有機エレクトロルミネッセンス素子。

（一般式（II）中、
Ｘ_１０１は、ＮＲ_１０１、酸素原子、硫黄原子、スルフィニル基、スルホニル基、ＣＲ_１０２Ｒ_１０３又はＳｉＲ_１０４Ｒ_１０５を表し、
Ｒ_１０１〜Ｒ_１０５は、各々水素原子又は置換基を表し、互いに結合して環を形成してもよく、
Ａｒ_１０１及びＡｒ_１０２は、各々独立に、置換されていてもよいアリール基、又は置換されていてもよいヘテロアリール基を表し、
ｎ１０２は０〜４の整数を表す。）
［２０］ ［１１］〜［１９］のいずれか一項に記載の有機エレクトロルミネッセンス素子を含む、表示装置。
［２１］ ［１１］〜［１９］のいずれか一項に記載の有機エレクトロルミネッセンス素子を含む、照明装置。 [18] The organic electroluminescence device according to [15] or [17], wherein the host compound has a structure represented by the following general formula (I).

(In the general formula (I),
X ₁₀₁ represents NR ₁₀₁ , an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₄ R ₁₀₅ ,
y _{1 to} y ₈ each independently represent CR ₁₀₆ or a nitrogen atom,
R _{101 to} R ₁₀₆ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring,
Ar ₁₀₁ and Ar ₁₀₂ each independently represent an optionally substituted aryl group or an optionally substituted heteroaryl group,
n101 and n102 each represent an integer of 0 to 4.
However, when R ₁₀₁ is a hydrogen atom, n ₁₀₁ represents an integer of 1 to 4. )
[19] The organic electroluminescent device according to [18], wherein the host compound having a structure represented by the general formula (I) has a structure represented by the following general formula (II).

(In the general formula (II),
X ₁₀₁ represents NR ₁₀₁ , an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₄ R ₁₀₅ ,
R _{101 to} R ₁₀₅ each represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring,
Ar ₁₀₁ and Ar ₁₀₂ each independently represent an optionally substituted aryl group or an optionally substituted heteroaryl group,
n102 represents an integer of 0 to 4. )
[20] A display device including the organic electroluminescence element according to any one of [11] to [19].
[21] A lighting device including the organic electroluminescence element according to any one of [11] to [19].

By the above means of the present invention, it is possible to provide a new π-conjugated compound capable of improving the light emission efficiency of an organic electroluminescence device, for example. Furthermore, by the above means of the present invention, it is possible to provide a new organic electroluminescence device that realizes improvement in luminous efficiency. Further, it is possible to provide an organic electroluminescence element material, a light emitting thin film, a light emitting material using the π-conjugated compound, and a display device and a lighting device provided with the organic electroluminescence element.

It is the schematic diagram which showed the energy diagram of a TADF compound. It is a schematic diagram showing an energy diagram of a general fluorescent material. FIG. 3 is a schematic diagram showing an energy diagram when a π-conjugated compound functions as an assist dopant material. It is a schematic diagram showing an energy diagram when a π-conjugated compound functions as a host material. It is a schematic diagram which showed an example of the display apparatus comprised from an organic EL element. It is a schematic diagram of a display device by an active matrix system. It is the schematic which showed the circuit of a pixel. It is a schematic diagram of a display device of a passive matrix system. It is a schematic diagram of an illuminating device. It is a schematic diagram of an illuminating device.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and after that as a lower limit and an upper limit.

In the π-conjugated compound containing a benzene ring, an electron-withdrawing group substituting the benzene ring, and at least two electron-donating groups, the electron-withdrawing group is an electron having an aromatic hetero 5-membered ring skeleton. and withdrawing group a ^1, further and para electron-withdrawing group a ^1, [pi conjugated compound having an electron-donating group on at least one neighbor, that can increase the luminous efficiency of the example organic electroluminescence element Found. The reason is not always clear, but it is presumed as follows.

Aromatic hetero 5-membered ring compounds (eg, triazole, oxazole, etc.) and condensed ring compounds having an aromatic hetero 5-membered ring skeleton (eg, benzotriazole, benzoxazole, etc.) are compounds expected as electron withdrawing groups of TADF compounds. Is. The π-conjugated compound of the present invention has an electron-withdrawing group having an aromatic hetero 5-membered ring skeleton as the electron-withdrawing group. Such an electron-withdrawing group can be an acceptor site. Furthermore, by satisfying the specific constitution of having an electron-donating group D in the para position farthest from the electron-withdrawing group and adjacent to at least one of the para-positions (that is, one combination of the ortho-positions of the benzene ring), It is considered that the electron donating property can be obtained. This is because, in addition to the presence of two or more electron-donating groups, they are substituted at the ortho position of the benzene ring, that is, "adjacent in space". When the electron-donating groups are adjacent to each other in space, a plurality of electron-donating groups can be spatially resonated to stabilize the positive charge carried by the electron-donating moiety in the excited state. It is considered that the emission is stabilized and the non-radiative deactivation is suppressed, and the luminous efficiency can be improved. Furthermore, it is considered that the electron-donating group D interacts not in through-bonding but in through-space, so that the absorption spectrum and the emission spectrum can be prevented from having a longer wavelength.

<π-conjugated compound>
The π-conjugated compound of the present invention is a compound having a structure represented by the following general formula (1).

In the general formula (1),
A ¹ represents an electron-withdrawing group having an optionally substituted aromatic hetero 5-membered ring skeleton,
D ¹ and D ² each independently represent an electron-donating group,
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group.

(About A ¹ )
A ¹ is an electron-attracting group having an optionally substituted aromatic hetero 5-membered ring skeleton. The electron-withdrawing group having an optionally substituted aromatic hetero 5-membered ring skeleton is an electron-withdrawing aromatic hetero 5-membered monocyclic compound (for example, triazole or oxazole) or an electron-withdrawing aromatic It is a group derived from a condensed ring compound having a hetero 5-membered ring skeleton (eg, benzotriazole, benzoxazole, etc.). Such a group is not only excellent as an electron-withdrawing group, but also easily available and easily organically synthesized. Therefore, it is suitable as an electron-withdrawing group of a TADF compound.

The bond of the “group derived from a fused ring compound having an electron-withdrawing aromatic hetero 5-membered ring skeleton” may be derived from a constituent atom of the aromatic hetero 5-membered ring skeleton, or otherwise. May come out of the aromatic ring. The bond of the “group derived from a condensed ring compound having an electron-withdrawing aromatic hetero 5-membered ring skeleton” is a constituent atom of the aromatic hetero 5-membered ring skeleton from the viewpoint that good electron withdrawing property is easily obtained. Is preferred.

Examples of the hetero atom constituting the electron-withdrawing aromatic hetero 5-membered ring skeleton include a nitrogen atom, a boron atom, an oxygen atom, a sulfur atom, a silicon atom, a phosphorus atom and the like. Of these, a sulfur atom or a nitrogen atom is preferable, and a nitrogen atom is more preferable. An electron-attracting group containing a nitrogen atom in the aromatic hetero 5-membered ring skeleton is more preferable because it has higher electron withdrawing property and higher stability.

The “electron-withdrawing group having an aromatic hetero 5-membered ring skeleton” represented by A ¹ is a group derived from a heterocycle having an electron-withdrawing aromatic hetero 5-membered ring skeleton having 1 to 30 carbon atoms. Is preferred. Examples of such heterocyclic groups include:
Pyrrole ring, imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene ring Oxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide ring,
Indole ring, benzimidazole ring, indazole ring, benzotriazole ring, benzofuran ring, benzoxazole ring, benzooxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophene ring Ring, dibenzothiophene dioxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring,
Azacarbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, azadibenzophosphole ring, azadibenzophosphole oxide ring,
Etc. are included.

Since the heterocycle having an electron-withdrawing aromatic hetero 5-membered ring skeleton exhibits a good electron-withdrawing property, it is preferably a heterocycle having an electron-withdrawing nitrogen-containing aromatic 5-membered ring skeleton. A nitrogen-containing aromatic 5-membered monocyclic compound having an attractive property is more preferable, and a triazole ring or a thiazole ring is further preferable.

The aromatic hetero 5-membered ring skeleton in the "group having an electron-withdrawing aromatic hetero 5-membered ring skeleton" may further have a substituent. Examples of such a substituent include "fluorine atom", "alkyl group substituted with fluorine atom", "optionally substituted carbonyl group", "optionally substituted sulfonyl group", "substituted" Optionally substituted phosphine oxide group”, “optionally substituted boryl group”, “optionally substituted aryl group (preferably aryl group optionally substituted with electron withdrawing group)”, and The “optionally substituted electron-withdrawing heterocyclic group” is included.

The alkyl group in the “alkyl group substituted with a fluorine atom” has the same meaning as the above alkyl group. Examples of the alkyl group substituted by _{fluorine, -CF 3, -CF 2 H,} -CH 2 F, include _-CF 2 CF ₃ and the like.

Examples of the substituents in the “optionally substituted carbonyl group”, the “optionally substituted sulfonyl group”, the “optionally substituted phosphine oxide group” and the “optionally substituted boryl group” Include a deuterium atom, a fluorine atom, a cyano group, an alkyl group which may be substituted with a fluorine atom, an aryl group which may be substituted, and an electron-withdrawing heterocyclic group which may be substituted.

The aryl group in the "optionally substituted aryl group" has the same meaning as the above aryl group.

Examples of the substituent which the aryl group may have include a deuterium atom, a fluorine atom, a cyano group, an alkyl group which may be substituted with fluorine, an optionally substituted carbonyl group, and an optionally substituted carbonyl group. It includes a sulfonyl group, an optionally substituted phosphine oxide group, an optionally substituted boryl group, an optionally substituted electron-withdrawing heterocyclic group, and an optionally substituted amino group.
Among them, the substituent that the aryl group may have is preferably an electron-withdrawing group, a fluorine atom, a cyano group, an alkyl group optionally substituted by fluorine, an optionally substituted carbonyl group, a substituent Optionally substituted sulfonyl group, optionally substituted phosphine oxide group, optionally substituted boryl group, and optionally substituted electron withdrawing heterocyclic group; fluorine atom, cyano group, An alkyl group optionally substituted with fluorine and an electron-withdrawing heterocyclic group optionally substituted are more preferable.

The "optionally substituted electron-withdrawing heterocyclic group" includes, in addition to the "group having an aromatic hetero 5-membered ring skeleton" represented by A ¹ , a pyridine ring, a pyridazine ring, a pyrimidine ring, From an electron-withdrawing aromatic heterocycle other than A ¹ such as a pyrazine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, a phenanthridine ring, and a phenanthroline ring. Induced groups are included. Note that these heterocycles are not condensed with the aromatic ring of the aryl group.

Examples of the substituent that the electron-withdrawing heterocyclic group may have include a deuterium atom, a fluorine atom, a cyano group, an alkyl group which may be substituted with fluorine, and an alkyl group which may be substituted with fluorine. Include an aryl group optionally substituted with, an aryl group optionally substituted with fluorine; preferably a fluorine atom, a cyano group, an alkyl group optionally substituted with fluorine, and a fluorine substituted Is also an aryl group.

(About D ¹ and D ² )
D ¹ and D ² are each independently an electron donating group. The electron-donating group is an "aryl group substituted with an electron-donating group", "an optionally substituted electron-donating heterocyclic group", "an optionally substituted amino group", or an "alkyl group". Can be.

The aryl group in the “aryl group substituted with an electron-donating group” represented by D is preferably a group derived from an aromatic hydrocarbon ring having 6 to 24 carbon atoms. Examples of such aromatic hydrocarbon rings include benzene ring, indene ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, acenaphthylene ring, biphenylene ring, naphthacene ring, pyrene ring, pentalene ring, acean ring. Tolylene ring, heptalene ring, triphenylene ring, as-indacene ring, chrysene ring, s-indacene ring, pleiadene ring, phenalene ring, fluoranthene ring, perylene ring, acephenanthrylene ring, biphenyl ring, terphenyl ring, and A tetraphenyl ring and the like are included. Among them, a benzene ring, naphthalene ring, fluorene ring, phenanthrene ring, anthracene ring, biphenylene ring, chrysene ring, pyrene ring, triphenylene ring, chrysene ring, fluoranthene ring, perylene ring, biphenyl ring, and terphenyl ring are preferable.

Examples of the electron donating group contained in the aryl group include an alkyl group, an alkoxy group, an optionally substituted amino group, and an optionally substituted electron donating heterocyclic group. Of these, an optionally substituted amino group and an optionally substituted electron-donating heterocyclic group are preferable.

The alkyl group may be linear, branched or cyclic, and may be, for example, a linear or branched alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 5 to 20 carbon atoms. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, cyclohexyl group. Group, 2-ethylhexyl group, n-heptyl group, n-octyl group, 2-hexyloctyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n- It includes a tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n-icosyl group and the like; preferably a methyl group, an ethyl group, an isopropyl group, t -Butyl group, cyclohexyl group, 2-ethylhexyl group and 2-hexyloctyl group.

The alkoxy group may be linear, branched or cyclic, and may be, for example, a linear or branched alkoxy group having 1 to 20 carbon atoms or a cyclic alkoxy group having 6 to 20 carbon atoms. Examples of the alkoxy group include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, t-butoxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group. Group, cyclohexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group, nonyloxy group, decyloxy group, 3,7-dimethyloctyloxy group, n-undecyloxy group, n-dodecyloxy group Group, n-tridecyloxy group, n-tetradecyloxy group, 2-n-hexyl-n-octyloxy group, n-pentadecyloxy group, n-hexadecyloxy group, n-heptadecyloxy group, n -Octadecyloxy group, n-nonadecyloxy group, n-icosyloxy group and the like are included, and preferably methoxy group, ethoxy group, isopropoxy group, t-butoxy group, cyclohexyloxy group, 2-ethylhexyloxy group, 2-hexyloctyl group. It is an oxy group.

Examples of the substituent of the amino group which may be substituted include an alkyl group and an aryl group which may be substituted with an alkyl group. The alkyl group and the aryl group have the same meanings as the above-mentioned alkyl group and aryl group (in the aryl group substituted with an electron-donating group), respectively.

Examples of the electron-donating heterocyclic group which may be substituted include those similar to the electron-donating heterocyclic group described below.

The "electron-donating heterocyclic group" in the "optionally substituted electron-donating heterocyclic group" represented by D is a group derived from an electron-donating heterocyclic ring having 4 to 24 carbon atoms. Is preferred. Examples of such a heterocycle include a pyrrole ring, an indole ring, a carbazole ring, an indoloindole ring, a 9,10-dihydroacridine ring, a phenoxazine ring, a phenothiazine ring, a dibenzothiophene ring, a benzofurylindole ring, a benzothieno ring. Examples include an indole ring, an indolocarbazole ring, a benzofurylcarbazole ring, a benzothienocarbazole ring, a benzothienobenzothiophene ring, a benzocarbazole ring, a dibenzocarbazole ring, an azacarbazole ring, and a diazacarbazole ring. Of these, a carbazole ring, an indoloindole ring, a 9,10-dihydroacridine ring, a phenoxazine ring, a phenothiazine ring, a dibenzothiophene ring, and a benzofurylindole ring are preferable. The electron-donating heterocyclic group may be a combination of two or more of the same or different heterocyclic groups bonded via a single bond.

Examples of the substituent which the heterocyclic group may have include an alkyl group and an aryl group which may be substituted with an alkyl group. The alkyl group and the aryl group have the same meanings as the above-mentioned alkyl group and aryl group, respectively.

Examples of the substituent in the “optionally substituted amino group” represented by D include an alkyl group and an aryl group optionally substituted with an alkyl group. The alkyl group and the aryl group may be the same as the aforementioned alkyl group and aryl group, respectively.

The “alkyl group” represented by D has the same meaning as the above alkyl group.

Among these, the electron donating group D is preferably an “optionally substituted electron donating heterocyclic group” because it has a high electron donating property.

(About Z ^{1 to} Z ³ )
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group.

The electron donating group used as Z ^{1 to} Z ³ has the same meaning as the electron donating group described above.

The electron-withdrawing group used as Z ^{1 to} Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an optionally substituted phosphine. Examples thereof include an oxide group, an optionally substituted boryl group, an aryl group optionally substituted by an electron withdrawing group, and an optionally substituted electron withdrawing heterocyclic group. These are synonymous with the substituents that the electron-withdrawing aromatic heterocyclic 5-membered ring skeleton may have.

（一般式（２）中、
Ａ^１は、一般式（１）のＡ^１と同義であり、
Ｄ^１〜Ｄ^３は、それぞれ一般式（１）のＤ^１及びＤ^２と同義であり、
Ｚ^２及びＺ^３は、それぞれ一般式（１）のＺ^１〜Ｚ^３と同義である） In the π-conjugated compound of the present invention, it is preferable that Z ¹ in the general formula (1) represents an electron donating group (see the following general formula (2)). When Z ¹ is an electron-donating group, both sides of D ¹ which is an electron-donating group in the para position with respect to A ¹ which is an electron-withdrawing group become an electron-donating group and three electron-donating groups are formed. The structure is such that replacement is performed at positions that are adjacent to each other. In such a structure, the rotational movement of the central electron donating group (electron donating group D ¹ ) sandwiched between the two electron donating groups is suppressed, and the excited state as a compound is further stabilized.

(In the general formula (2),
A ¹ has the same meaning as A ^{1 in} formula (1),
D ^{1 to} D ³ are synonymous with D ¹ and D ² of the general formula (1), respectively,
Z ² and Z ³ have the same meanings as Z ^{1 to} Z ^{3 in} formula (1), respectively.

（一般式（３）中、
Ａ^１は、一般式（１）のＡ^１と同義であり、
Ｄ^１〜Ｄ^３は、それぞれ一般式（１）のＤ^１及びＤ^２と同義である） Further, in the π-conjugated compound of the present invention, it is more preferable that Z ¹ is an electron-donating group D and that Z ² and Z ³ are hydrogen atoms (see the following general formula (3)). When Z ¹ is an electron-donating group D and Z ² and Z ³ are hydrogen atoms, the donor site and the acceptor site are separated from each other by an appropriate distance. It is preferable because charge transfer to the acceptor does not occur.

(In the general formula (3),
A ¹ has the same meaning as A ^{1 in} formula (1),
D ^{1 to} D ³ have the same meanings as D ¹ and D ^{2 in} formula (1), respectively.

The π-conjugated compound having the structure represented by the general formula (1) is an organic electroluminescent device material containing the π-conjugated compound, a light emitting thin film containing the π-conjugated compound, and the π-conjugated compound. It can be used as an organic electroluminescence device containing a compound.

The π-conjugated compound having the structure represented by the general formula (1) becomes excited by electric field excitation and can generate excitons. Therefore, the π-conjugated compound having the structure represented by the general formula (1) is preferably contained in the light emitting layer of the organic electroluminescence device. That is, in the light emitting layer, from the viewpoint of high light emission, the π-conjugated compound having the structure represented by the general formula (1) is used alone or the π conjugated compound having the structure represented by the general formula (1) is used. Containing a conjugated compound and a host compound described below; a π-conjugated compound having a structure represented by the general formula (1), and at least one of a fluorescent emitting compound and a phosphorescent emitting compound described below. Or a π-conjugated compound having a structure represented by the general formula (1), at least one of a fluorescent emitting compound and a phosphorescent emitting compound described below, and a host compound described below. It is preferable to contain

In the π-conjugated compound having the structure represented by the general formula (1), the absolute value (ΔE _ST ) of the energy difference between the lowest excited singlet level and the lowest excited triplet level of the π-conjugated compound is It is preferably 0.50 eV or less, and is preferably contained in the organic electroluminescence element, the element material, or the light emitting thin film.

The organic electroluminescent element of the present invention can be suitably provided in a lighting device and a display device.

Hereinafter, preferred specific examples of the π-conjugated compound according to the present invention will be given. However, these compounds may further have a substituent or may have structural isomers, etc., and are limited to the present description. Not done.

The absolute value of the following materials 0.50eV of Delta] E _ST of these compounds are shown TADF resistance (delay fluorescent), i.e. may emit delayed fluorescence. Here, the expression of delayed fluorescence means that there are two or more kinds of components having different decay rates of emitted fluorescence when fluorescence decay measurement is performed. Note that the components with slow decay generally have a decay time of submicroseconds or more in general, but the decay time is not limited because the decay time differs depending on the material. The fluorescence decay measurement can be generally performed as follows. A solution or thin film of a π-conjugated compound (light-emitting compound) or a co-deposited film of a π-conjugated compound and a second component is irradiated with excitation light in a nitrogen atmosphere, and the number of photons having a certain emission wavelength is measured. At this time, the π-conjugated compound exhibits delayed fluorescence when there are two or more components having different decay rates of the emitted fluorescence.

Furthermore, since these compounds have a bipolar property and can cope with various energy levels, they can be used not only as a light-emitting host but also as a compound suitable for hole transport and electron transport. Therefore, it is not limited to use in the light emitting layer, and may be used in the above-mentioned hole injection layer, hole transport layer, electron blocking layer, hole blocking layer, electron transport layer, electron injection layer, intermediate layer and the like. ..

<Synthesis method>
Examples of the π-conjugated compound include those disclosed in International Publication No. 2010/113755, Organic Letters, 2002, 4, 1783-1785. , Angew. Chem. Int. Ed. 2010, 49, 2014-2017. Or the methods described in the references described in these documents.

Next, the light emitting system and the light emitting material of the organic EL, which are related to the technical idea of the present invention, will be described.

<Organic EL emission method>
There are two types of organic EL emission methods: "phosphorescence emission" that emits light when returning from the triplet excited state to the ground state, and "fluorescence emission" that emits light when returning from the singlet excited state to the ground state. is there.
When excited by an electric field such as an organic EL, triplet excitons are generated with a probability of 75% and singlet excitons are generated with a probability of 25%. Therefore, phosphorescence emission is more efficient than fluorescence emission. It is an excellent method for realizing low power consumption.
On the other hand, even in fluorescence emission, triplet excitons, which normally generate heat with a probability of 75% and are only heat due to non-radiative deactivation, are caused to exist at high density. A method using a TTA (triplet-triplet annealing, or abbreviated as "triple-triplet fusion (TTF)") mechanism for generating one singlet exciton from two triplet excitons to improve light emission efficiency. Found

Further, in recent years, by the discovery of Adachi et al., by making the energy gap between the singlet excited state and the triplet excited state small, triple energy with low energy level due to Joule heat during light emission and/or environmental temperature where the light emitting element is placed. A phenomenon in which an inverse intersystem crossing occurs from a term excited state to a singlet excited state, and as a result, fluorescence emission close to 100% is possible (also referred to as thermally excited delayed fluorescence or thermally excited delayed fluorescence: “TADF”). A fluorescent substance that enables this has been found (for example, see Non-Patent Document 1).

<Phosphorescent compound>
As described above, phosphorescence is theoretically three times more advantageous in terms of luminous efficiency than fluorescence, but energy deactivation (=phosphorescence) from the triplet excited state to the singlet ground state is forbidden. Since it is a transition, and similarly, intersystem crossing from a singlet excited state to a triplet excited state is also a forbidden transition, its rate constant is usually small. That is, since transition is less likely to occur, the exciton lifetime is extended from millisecond to second order, and it is difficult to obtain desired light emission.
However, when a complex using a heavy metal such as iridium or platinum emits light, the heavy atom effect of the central metal increases the rate constant of the above-mentioned forbidden transition by three orders of magnitude or more, and depending on the selection of the ligand, 100 It is also possible to obtain a phosphorescence quantum yield of %.
However, in order to obtain such ideal light emission, it is necessary to use a precious metal called a so-called white metal such as iridium, palladium, or platinum, which is a rare metal, and when it is used in a large amount, its reserves or The price of metal itself becomes a big problem in industry.

<Fluorescent compound>
A general fluorescent compound does not need to be a heavy metal complex such as a phosphorescent compound, and is a so-called organic compound composed of a combination of general elements such as carbon, oxygen, nitrogen and hydrogen. Can be applied, and other non-metal elements such as phosphorus, sulfur, and silicon can be used, and the complex of typical metals such as aluminum and zinc can be utilized.
However, in the conventional fluorescent compound, since only 25% of excitons can be applied to the light emission as described above, highly efficient light emission such as phosphorescence cannot be expected.

<Delayed fluorescent compound>
[Excited triplet-triplet annihilation (TTA) delayed fluorescent compound]
A light emitting method using delayed fluorescence has appeared to solve the problems of the fluorescent compound. The TTA method, which originates from the collision of triplet excitons, can be described by the following general formula. That is, conventionally, the energy of excitons has a merit that a part of triplet excitons, which has been converted into only heat by non-radiative deactivation, can cross the singlet excitons that can contribute to light emission. In the actual organic EL device, the external extraction quantum efficiency about twice that of the conventional fluorescent light emitting device can be obtained.
General formula: T ^* +T ^* →S ^* +S
(In the formula, T ^* represents triplet excitons, S ^* represents singlet excitons, and S represents a ground state molecule.)
However, as can be seen from the above equation, since only one singlet exciton that can be used for light emission is generated from two triplet excitons, it is theoretically impossible to obtain 100% internal quantum efficiency by this method.

[Thermal activated delayed fluorescence (TADF) compound]
Another highly efficient fluorescent emission, the TADF method, is a method that can solve the problems of TTA.
Fluorescent compounds have the advantage that they can be designed infinitely as described above. That is, among the compounds whose molecules are designed, there are compounds in which the energy level difference between the triplet excited state and the singlet excited state is extremely close to each other.
Such compounds, even though in the molecule does not have a heavy atom, reverse intersystem crossing from a triplet excited state is usually not occur because Delta] E _ST is smaller to the singlet excited state occurs. Furthermore, since the rate constant of deactivation (=fluorescence emission) from the singlet excited state to the ground state is extremely large, the triplet exciton itself is thermally deactivated to the ground state (non-radiative deactivation). It is kinetically advantageous to return to the ground state while emitting fluorescence via the singlet excited state. Therefore, TADF theoretically enables 100% fluorescence emission.

<Molecular design concepts related to ΔE _ST>
It explained molecular design for reducing the Delta] E _ST.
ΔE in order to reduce the _ST is highest occupied molecular orbital in principle molecules (Highest Occupied Molecular Orbital: HOMO) and lowest unoccupied molecular orbital (Lowest Unoccupied Molecular Orbital: LUMO) spatial overlap the small to most effects of Target.
It is generally known that in the electron orbit of a molecule, HOMO is distributed in the electron-donating site and LUMO is distributed in the electron-withdrawing site. It is possible to move away the position where and LUMO exist.

For example, in “Applied Physics at the Practical Stage”, Applied Physics Vol. 82, No. 6, 2013, electron-withdrawing skeletons such as cyano group and triazine, and electron donating such as carbazole and diphenylamino group. By introducing a sex skeleton, LUMO and HOMO are localized.
It is also effective to reduce the change in molecular structure between the ground state and the triplet excited state of the compound. As a method for reducing the structural change, for example, making the compound rigid is effective. The rigidity described here means that there are few sites that can move freely in the molecule, such as suppressing free rotation in the bond between rings in the molecule and introducing a condensed ring with a large π-conjugated plane. means. In particular, it is possible to reduce the structural change in the excited state by making the region involved in light emission rigid.

<General problems of TADF compounds>
TADF compounds have various problems in terms of their light emitting mechanism and molecular structure. The following describes some of the problems that TADF compounds generally have.
In TADF compound, it is necessary to release as possible sites present in the HOMO and LUMO in order to reduce the Delta] E _ST, Therefore, the electronic state of the molecule of the donor / acceptor type HOMO site and LUMO sites separated The state becomes close to intramolecular CT (intramolecular charge transfer state).

When a plurality of such molecules are present, stabilization is achieved by bringing the donor part of one molecule and the acceptor part of the other molecule into close proximity. Such a stable state is not limited to the formation between two molecules, but can be formed between a plurality of molecules such as between three molecules or between five molecules, and as a result, various stable states having a wide distribution can be obtained. As a result, the shape of the absorption spectrum and the emission spectrum becomes broad. Further, even when a multi-molecular aggregate of more than two molecules is not formed, various existence states can exist depending on the difference in the interaction direction and angle of the two molecules, so basically the absorption spectrum and the The shape of the emission spectrum is broad.

Broad emission spectrum causes two major problems. First, there is a problem that the color purity of the emission color is low. This is not a big problem when applied to lighting applications, but when used for electronic display applications, the color gamut is small and the color reproducibility of pure colors is low, so it is actually applied as a product. Will be difficult.

Another problem is that the rising wavelength on the short wavelength side of the emission spectrum (called “fluorescence 0-0 band”) is shortened, that is, S _{1 is} increased (energy of the lowest excited singlet energy level is increased). Is to do.
As a matter of course, when the fluorescence 0-0 band has a shorter wavelength, the phosphorescence 0-0 band derived from T ₁ having lower energy than S ₁ also has a shorter wavelength (increases the T ₁ level). Therefore, the compound used as the host compound needs to have a high S ₁ level and a high T ₁ level in order to prevent reverse energy transfer from the dopant.
This is a very big problem. Basically, a host compound consisting of an organic compound has a plurality of active and unstable chemical species such as a cation radical state, an anion radical state and an excited state in an organic EL device. By expanding the π-conjugated system of, it can exist relatively stably.

However, in order to impart a high S ₁ level and a high T ₁ level to a molecule, it is necessary to reduce or cut off the π-conjugated system in the molecule, which makes it difficult to achieve compatibility with stability. As a result, the life of the light emitting element is shortened.
In addition, in a TADF compound that does not contain a heavy metal, the transition that deactivates from the triplet excited state to the ground state is a forbidden transition. Therefore, the existence time (exciton lifetime) in the triplet excited state is several hundred microseconds to millisecond. Very long, on the order of seconds. Therefore, even if the T ₁ energy level of the host compound is higher than that of the fluorescence emitting compound, the triplet excited state of the fluorescence emitting compound changes to the host compound due to the length of the existence time. The probability of reverse energy transfer increases. As a result, undesired reverse energy transfer to the host compound becomes mainstream without sufficient intersystem crossing from the triplet excited state to the singlet excited state of the originally intended TADF compound, resulting in sufficient luminous efficiency. Will not be obtained.

In order to solve the above problems, it is necessary to sharpen the emission spectrum shape of the TADF compound and reduce the difference between the emission maximum wavelength and the rising wavelength of the emission spectrum. For that purpose, it can be basically achieved by reducing the change in the molecular structure of the singlet excited state and the triplet excited state.
Further, in order to suppress the reverse energy transfer to the host compound, it is effective to shorten the existence time (exciton lifetime) of the triplet excited state of the TADF compound. In order to realize it, it is necessary to reduce the change in the molecular structure between the ground state and the triplet excited state, and to take measures such as introducing a substituent or an element suitable for breaking the forbidden transition. It is possible to solve

In the present invention, in a π-conjugated compound having a benzene ring, an electron-withdrawing group A substituting for the benzene ring, and an electron-donating group D, at least one combination of ortho-positions substituting for the benzene ring is selected as “electron-donating group”. And the electron-donating group D, the electron-withdrawing group A and the electron-withdrawing group A, and the electron-withdrawing group A and the electron-donating group D.

Two or more electron-donating groups (or two or more electron-withdrawing groups A) are substituted at the ortho position of the benzene ring; that is, "adjacent in space" so that they are electron-donating in the excited state. The electron-donating group (or electron-withdrawing group) can be spatially resonated to stabilize the positive charge (or the negative charge of the electron-withdrawing portion) of the moiety, stabilizing the excited state. Therefore, it is considered that the non-radiative deactivation is suppressed and the luminous efficiency can be improved.

By disposing the electron-withdrawing group A and the electron-donating group D at the ortho position of the benzene ring, the electron-withdrawing group D and the electron-withdrawing group A are "spatial adjacent". As a result, a CT-state excited state is not formed from the electron-donating group D to the electron-withdrawing group A via a bond, but between the electron-donating group D and the electron-withdrawing group A located in the immediate vicinity. It is considered that the CT-excited state can be formed and the CT-excited state is stabilized, so that the luminous efficiency is increased.

Further, in any of the embodiments, since the electron-withdrawing group A and the electron-donating group D interact with each other through the through space instead of connecting through the through bond, the absorption spectrum and the emission spectrum are prevented from becoming longer wavelength. It is thought to be possible.

Hereinafter, various measuring methods for the π-conjugated compound according to the present invention will be described.

[Electron density distribution]
Π conjugated compound according to the present invention, from the viewpoint of reducing the Delta] E _ST, it is preferable that HOMO and LUMO are substantially separated in the molecule. The distribution states of these HOMO and LUMO can be obtained from the electron density distribution when the structure is optimized, which is obtained by molecular orbital calculation.
The structure optimization and the calculation of the electron density distribution by the molecular orbital calculation of the π-conjugated compound in the present invention are performed by using the software for molecular orbital calculation using B3LYP as the functional and 6-31G(d) as the basis function as the calculation method. It can be calculated using any software, and there is no particular limitation on the software, and the same can be obtained using any software.
In the present invention, Gaussian09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010.) manufactured by Gaussian, Inc., USA was used as the software for molecular orbital calculation.

Further, "the HOMO and the LUMO are substantially separated" means that the central portions of the HOMO orbital distribution and the LUMO orbital distribution calculated by the above-mentioned molecular calculation are apart from each other, and more preferably the distribution of the HOMO orbital and the LUMO orbital. It means that the distributions of do not almost overlap.
Regarding the separated state of HOMO and LUMO, from the structure optimization calculation using B3LYP as the above-mentioned functional and 6-31G(d) as the basis function, further by the time-dependent density functional method (Time-Dependent DFT). Excited state calculation is performed to obtain energy levels of S ₁ and T ₁ (E(S ₁ ), E(T ₁ ), respectively) and ΔE _ST =|E(S ₁ )−E(T ₁ )| It is also possible to calculate. As calculated Delta] E _ST is small, indicating that the HOMO and LUMO are more separated. In the present invention, it is Delta] E _ST calculated using the calculation method similar to that described above or less 0.50EV, preferably not more than 0.30 eV, more preferably not more than 0.10 eV.

[Lowest excited singlet energy level S ₁ ]
The lowest excited singlet energy level S ₁ of the π-conjugated compound in the present invention is defined as that calculated in the same manner as in the usual method in the present invention. That is, a compound to be measured is deposited on a quartz substrate to prepare a sample, and the absorption spectrum (vertical axis: absorbance, horizontal axis: wavelength) of this sample is measured at room temperature (300K). A tangent line is drawn to the rising edge on the long wavelength side of this absorption spectrum, and it is calculated from a predetermined conversion formula based on the wavelength value at the intersection of the tangent line and the horizontal axis.
However, if the molecule itself of the π-conjugated compound used in the present invention has a relatively high aggregation property, an error due to aggregation may occur in the measurement of the thin film. Considering that the π-conjugated compound in the present invention has a relatively small Stokes shift and the structural change between the excited state and the ground state is small, the lowest excited singlet energy level S ₁ in the present invention is at room temperature (25° C.). The peak value of the maximum emission wavelength in the solution state of the π-conjugated compound in) was used as an approximate value.
Here, as the solvent to be used, a solvent that does not affect the aggregation state of the π-conjugated compound, that is, a solvent that is less affected by the solvent effect, for example, a nonpolar solvent such as cyclohexane or toluene can be used.

[Lowest excited triplet energy level T ₁ ]
The lowest excited triplet energy level (T ₁ ) of the π-conjugated compound used in the present invention was calculated from the photoluminescence (PL) characteristics of the solution or thin film. For example, as a calculation method for a thin film, after a dispersion of a diluted π-conjugated compound is formed into a thin film, a transient PL characteristic is measured using a streak camera to separate a fluorescent component and a phosphorescent component, the absolute value of the energy difference can be determined the lowest excited triplet energy level of the lowest excited singlet energy level as Delta] E _ST.
In measuring and evaluating the absolute PL quantum yield, an absolute PL quantum yield measuring device C9920-02 (manufactured by Hamamatsu Photonics KK) was used. The emission lifetime was measured using a streak camera C4334 (manufactured by Hamamatsu Photonics) while exciting the sample with laser light.

<<Organic EL element constituent layers>>
The organic EL element of the present invention is an organic electroluminescence element having at least a light emitting layer between an anode and a cathode, and at least one layer of the light emitting layer has a structure represented by the general formula (1). It is characterized by containing a conjugated compound.
Typical element configurations of the organic EL element of the present invention include, but are not limited to, the following configurations.
(1) Anode/light emitting layer//cathode (2) Anode/light emitting layer/electron transporting layer/cathode (3) Anode/hole transporting layer/light emitting layer/cathode (4) Anode/hole transporting layer/light emitting layer/ Electron transport layer/cathode (5) Anode/hole transport layer/light emitting layer/electron transport layer/electron injection layer/cathode (6) Anode/hole injection layer/hole transport layer/light emitting layer/electron transport layer/cathode (7) Anode/hole injection layer/hole transport layer/(electron blocking layer/) light emitting layer/(hole blocking layer/) electron transport layer/electron injection layer/cathode It is preferably used, but is not limited thereto.
The light emitting layer used in the present invention is composed of a single layer or a plurality of layers, and when there are a plurality of light emitting layers, a non-light emitting intermediate layer may be provided between the respective light emitting layers.

If necessary, a hole blocking layer (also called a hole blocking layer) or an electron injection layer (also called a cathode buffer layer) may be provided between the light emitting layer and the cathode. An electron blocking layer (also referred to as an electron barrier layer) or a hole injection layer (also referred to as an anode buffer layer) may be provided therebetween.
The electron transport layer used in the present invention is a layer having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. Also, it may be composed of a plurality of layers.
The hole transport layer used in the present invention is a layer having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. Also, it may be composed of a plurality of layers.
In the above-mentioned typical element structure, the layer excluding the anode and the cathode is also referred to as an “organic layer”.

(Tandem structure)
The organic EL element of the present invention may be an element having a so-called tandem structure in which a plurality of light emitting units including at least one light emitting layer are laminated.
Examples of typical tandem structure element configurations include the following configurations.
Anode/first light emitting unit/intermediate layer/second light emitting unit/intermediate layer/third light emitting unit/cathode Here, even if the first light emitting unit, the second light emitting unit and the third light emitting unit are all the same, May be different. Further, the two light emitting units may be the same and the other one may be different.
The plurality of light emitting units may be directly laminated or may be laminated with an intermediate layer interposed therebetween. A known material structure can be used as long as it is also called an insulating layer and has a function of supplying electrons to the adjacent layer on the anode side and supplying holes to the adjacent layer on the cathode side.

Examples of the material used for the intermediate layer include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO ₂ , TiN, ZrN, HfN, TiOx, VOx, CuI, InN, GaN, CuAlO ₂ , and A conductive inorganic compound layer such as CuGaO ₂ , SrCu ₂ O ₂ , LaB ₆ , RuO ₂ and Al, a two-layer film such as Au/Bi ₂ O ₃ and SnO ₂ /Ag/SnO ₂ , ZnO/Ag/ZnO. , Bi ₂ O ₃ /Au/Bi ₂ O ₃ , TiO ₂ /TiN/TiO ₂ , multilayer films such as TiO ₂ /ZrN/TiO ₂ , fullerene such as C ₆₀ , conductive organic material layer such as oligothiophene, Examples include conductive organic compound layers such as metal phthalocyanines, metal-free phthalocyanines, metal porphyrins, and metal-free porphyrins, but the present invention is not limited thereto.
Examples of preferable configurations in the light-emitting unit include those obtained by removing the anode and the cathode from the configurations (1) to (7) mentioned in the above representative element configurations, but the present invention is not limited thereto. Not limited.

Specific examples of the tandem organic EL device include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6,107,734, US Pat. Publication No. 2005/009087, JP 2006-228712 A, JP 2006-24791 A, JP 2006-49393 A, JP 2006-49394 A, JP 2006-49396 A, JP 2011 A. -96679, JP 2005-340187 A, JP 4711424 A, JP 34096681 A, JP 3884564 A, JP 4213169 A, JP 2010-192719 A, JP 2009-076929 A, JP Examples of the element configurations, constituent materials, and the like described in JP 2008-078414 A, JP 2007-059848 A, JP 2003-272860 A, JP 2003-045676 A, WO 2005/094130 and the like. However, the present invention is not limited to these.

Hereinafter, each layer constituting the organic EL device of the present invention will be described.

<Light emitting layer>
The light-emitting layer used in the present invention is a layer that provides a field where electrons and holes injected from an electrode or an adjacent layer are recombined and emit light via excitons, and the light-emitting portion is the light-emitting layer. It may be in the layer or at the interface between the light emitting layer and the adjacent layer. The structure of the light emitting layer used in the present invention is not particularly limited as long as it satisfies the requirements specified in the present invention.
The total thickness of the light emitting layer is not particularly limited, but the uniformity of the formed film and the application of an unnecessary high voltage during light emission are prevented, and the stability of the emission color with respect to the drive current is improved. From the viewpoint, it is preferably adjusted to the range of 2 nm to 5 μm, more preferably adjusted to the range of 2 to 500 nm, and further preferably adjusted to the range of 5 to 200 nm.
The layer thickness of each light-emitting layer used in the present invention is preferably adjusted to a range of 2 nm to 1 μm, more preferably adjusted to a range of 2 to 200 nm, and further preferably a range of 3 to 150 nm. Adjusted.
The light emitting layer used in the present invention may have a single layer or a plurality of layers. When the π-conjugated compound of the present application is used in the light emitting layer, it may be used alone, or may be used as a mixture with a host material, a fluorescent light emitting material, a phosphorescent light emitting material and the like described later. At least one of the light emitting layers contains a light emitting dopant (also referred to as a light emitting compound, a light emitting dopant, or simply a dopant) and further contains a host compound (also referred to as a matrix material, a light emitting host compound, or simply a host). preferable. In the π-conjugated compound of the present application, it is preferable that at least one layer of the light emitting layer contains the π-conjugated compound of the present application and the host compound, because the emission efficiency is improved. It is preferable that at least one of the light emitting layers contains the π-conjugated compound of the present application and at least one of the fluorescent light emitting compound and the phosphorescent light emitting compound, because the light emitting efficiency is improved. It is preferable that at least one layer of the light emitting layer contains the π-conjugated compound of the present application, at least one kind of the fluorescent light emitting compound and the phosphorescent light emitting compound, and the host compound since the light emitting efficiency is improved.

(1.1) Luminescent Dopant As a luminescent dopant, a fluorescent luminescent dopant (also referred to as a fluorescent luminescent compound or a fluorescent dopant) and a phosphorescent luminescent dopant (also referred to as a phosphorescent luminescent compound or a phosphorescent dopant). It is preferably used. In the present invention, the light emitting layer contains the π-conjugated compound according to the present invention as a fluorescent compound or an assist dopant within a range of 0.1 to 50% by mass, and particularly 1 to 30% by mass. It is preferably contained within the range.

In the present invention, the light emitting layer contains the light emitting compound in the range of 0.1 to 50% by mass, and particularly preferably in the range of 1 to 30% by mass.
The concentration of the light-emitting compound in the light-emitting layer can be arbitrarily determined based on the specific light-emitting compound used and the requirements of the device, and the concentration is uniform in the thickness direction of the light-emitting layer. It may be contained, and may have an arbitrary concentration distribution.
Further, the light-emitting compound used in the present invention may be used in combination of two or more kinds, and a combination of fluorescent light-emitting compounds having different structures or a combination of a fluorescent light-emitting compound and a phosphorescent light-emitting compound is used. You may. As a result, any luminescent color can be obtained.

The absolute value of the difference between the lowest excited singlet energy level and the lowest excited triplet energy level (Delta] E _ST) is a π conjugated compound according to the present invention which is a less 0.50EV, a luminescent compound, a host compound When contained in the light emitting layer, the π-conjugated compound according to the present invention acts as an assist dopant. On the other hand, when the light emitting layer contains the π-conjugated compound according to the present invention and the luminescent compound and does not contain the host compound, the π-conjugated compound according to the present invention acts as a host compound. When the light emitting layer contains only the π-conjugated compound according to the present invention, the π-conjugated compound according to the present invention acts as a host compound and a luminescent compound.
The mechanism for producing the effect is the same in any case, and the point of converting triplet excitons generated on the π-conjugated compound according to the present invention into singlet excitons by reverse intersystem crossing (RISC). It is in.
As a result, theoretically all the exciton energies generated on the π-conjugated compound according to the present invention can be transferred to the luminescent compound by fluorescence resonance energy transfer (FRET), and high luminescence efficiency can be realized.
Therefore, when the light emitting layer contains three components of the π-conjugated compound, the light-emitting compound and the host compound according to the present invention, the energy levels of S ₁ and T ₁ of the π-conjugated compound are S of the host compound. ₁ and T ₁ of the lower than the energy level, it is preferably higher than the energy level of the S ₁ and T ₁ of the light-emitting compound.
Similarly, light emitting layer, the energy level of the S ₁ and T ₁ of the case containing the two components of the light emitting compound and [pi conjugated compound according to the present invention, [pi-conjugated compounds, S ₁ luminescent compound And higher than the energy level of T ₁ .

3 and 4 are schematic views showing the case where the pi-conjugated compound of the present invention acts as an assist dopant and a host compound, respectively. FIG. 3 and FIG. 4 are examples, and the generation process of triplet excitons generated on the π-conjugated compound according to the present invention is not limited to electric field excitation, and energy transfer from the light emitting layer or from the peripheral layer interface. And electronic transfer are also included.
Further, in FIGS. 3 and 4, a fluorescent light emitting compound is used as the light emitting material, but the present invention is not limited to this, and a phosphorescent light emitting compound may be used, or a fluorescent light emitting compound and a phosphorescent light emitting compound may be used. Both of the sex compounds may be used.

When the π-conjugated compound according to the present invention is used as an assist dopant, the light-emitting layer contains a host compound in a mass ratio of 100% or more with respect to the π-conjugated compound, and has a fluorescence emitting compound and/or a phosphorescence emitting compound. Is preferably contained within a mass ratio range of 0.1 to 50% with respect to the π-conjugated compound.

When the π-conjugated compound according to the present invention is used as a host compound, the light emitting layer has a mass ratio of the fluorescent compound and/or the phosphorescent compound to the π-conjugated compound in the range of 0.1 to 50%. It is preferable to contain.

When the π-conjugated compound according to the present invention is used as an assist dopant or a host compound, it is preferable that the emission spectrum of the π-conjugated compound according to the present invention and the absorption spectrum of the luminescent compound overlap.

The luminescent color of the organic EL device of the present invention or the compound used in the present invention is shown in FIG. It is determined by the color when a result measured by a luminance meter CS-1000 (manufactured by Konica Minolta Co., Ltd.) is applied to CIE chromaticity coordinates.
In the present invention, it is also preferable that one or a plurality of light emitting layers contain a plurality of light emitting dopants having different light emitting colors and emit white light.
The combination of light emitting dopants exhibiting white is not particularly limited, and examples thereof include combinations of blue and orange, combinations of blue, green and red, and the like.
White in the organic EL device of the present invention means that the chromaticity in the CIE1931 color system at 1000 cd/m ² is x=0.39±0.09 when the 2° viewing angle front luminance is measured by the above method. , Y=0.38±0.08.

(1.2) Fluorescent Luminescent Dopant As the fluorescent luminescent dopant (fluorescent dopant), the π-conjugated compound of the present invention may be used, or a known fluorescent dopant or delayed fluorescence used in the light emitting layer of an organic EL device. You may select suitably from a sexual dopant and may be used.

Specific examples of known fluorescent dopants that can be used in the present invention include, for example, anthracene derivatives, pyrene derivatives, chrysene derivatives, fluoranthene derivatives, perylene derivatives, fluorene derivatives, arylacetylene derivatives, styrylarylene derivatives, styrylamine derivatives, arylamine derivatives. , Boron complex, coumarin derivative, pyran derivative, cyanine derivative, croconium derivative, squarylium derivative, oxobenzanthracene derivative, fluorescein derivative, rhodamine derivative, pyrylium derivative, perylene derivative, polythiophene derivative, or rare earth complex compound. Further, in recent years, luminescent dopants utilizing delayed fluorescence have been developed, and these may be used. Specific examples of the luminescent dopant using delayed fluorescence include compounds described in International Publication No. 2011/156793, JP 2011-213643 A, JP 2010-93181 A, JP 5366106 A, and the like. However, the present invention is not limited to these.

(1.3) Phosphorescent Luminescent Dopant The phosphorescent luminescent dopant used in the present invention will be described.
The phosphorescent dopant used in the present invention is a compound in which light emission from an excited triplet is observed, specifically, a compound which emits phosphorescence at room temperature (25° C.), and has a phosphorescence quantum yield. Is defined as a compound of 0.01 or more at 25° C., but a preferable phosphorescence quantum yield is 0.1 or more.
The phosphorescence quantum yield can be measured by the method described in Spectra II, 4th edition, Experimental Chemistry Course 7, page 398 (1992, Maruzen). The phosphorescence quantum yield in a solution can be measured using various solvents, but the phosphorescence dopant used in the present invention achieves the above phosphorescence quantum yield (0.01 or more) in any solvent. Just do it.

The phosphorescent dopant can be appropriately selected and used from known ones used for the light emitting layer of the organic EL device. Specific examples of known phosphorescent dopants that can be used in the present invention include compounds described in the following documents.
Nature 395, 151 (1998), Appl. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19, 739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17, 1059 (2005), International Publication No. 2009/100991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Application Publication No. 2006/835469, US Patent Application Publication No. 2006/ 0202194, U.S. Patent Application Publication No. 2007/0087321, U.S. Patent Application Publication No. 2005/0244673, Inorg. Chem. 40, 1704 (2001), Chem. Mater. 16, 2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chem. lnt. Ed. 2006, 45, 7800, Appl. Phys. Lett. 86,153505 (2005), Chem. Lett. 34, 592 (2005), Chem. Commun. 2906 (2005), Inorg. Chem. 42, 1248 (2003), International Publication No. 2009/050290, International Publication No. 2002/015645, International Publication No. 2009/000673, US Patent Application Publication No. 2002/0034656, US Patent No. 7332232, US Patent Application Publication No. 2009/0108737, U.S. Patent Application Publication No. 2009/00397776, U.S. Patent No. 6,921,915, U.S. Patent No. 6,687,266, U.S. Patent Application Publication No. 2007/0190359, U.S. Patent Application Publication 2006/0008670, US Patent Application Publication 2009/0165846, US Patent Application Publication 2008/0015355, US Patent 7250226, US Patent 7396598, US Patent Application Publication No. 2006/0263635, U.S. Patent Application Publication No. 2003/0138657, U.S. Patent Application Publication No. 2003/0152802, U.S. Patent No. 7,090,928, Angew. Chem. lnt. Ed. 47, 1 (2008), Chem. Mater. 18, 5119 (2006), Inorg. Chem. 46, 4308 (2007), Organometallics 23, 3745 (2004), Appl. Phys. Lett. 74, 1361 (1999), International Publication No. 2002/002714, International Publication No. 2006/009024, International Publication No. 2006/056418, International Publication No. 2005/019373, International Publication No. 2005/123873, International Publication No. 2005/123873, International Publication No. 2007/004380, International Publication No. 2006/082742, United States Patent Application Publication No. 2006/0251923, United States Patent Application Publication No. 2005/0260441, United States Patent No. 7393599. U.S. Patent No. 7,534,505, U.S. Patent No. 7,445,855, U.S. Patent Application Publication No. 2007/0190359, U.S. Patent Application Publication No. 2008/0297033, U.S. Patent No. 7,338,722, U.S. Patent Application Publication No. 2002/. No. 0134984, U.S. Pat. No. 7,279,704, U.S. Patent Application Publication No. 2006/098120, U.S. Patent Application Publication No. 2006/103874, International Publication No. 2005/076380, International Publication No. 2010/032663. , International Publication No. 2008140115, International Publication No. 2007/052431, International Publication No. 2011/134013, International Publication No. 2011/157339, International Publication No. 2010/086089, International Publication No. 2009/113646, International Publication No. 2012/020327, International Publication No. 2011/051404, International Publication No. 2011/004639, International Publication No. 2011/073149, US Patent Application Publication No. 2012/228583, US Patent Application Publication No. 2012/212126. Description, JP 2012-069737 A, Japanese Patent Application No. 2011-181303, JP 2009-114086 A, JP 2003-81988 A, JP 2002-302671 A, JP 2002-363552 A. Etc.
Among them, preferable phosphorescent dopants include organic metal complexes having Ir as a central metal. More preferably, a complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond and a metal-sulfur bond is preferable.

(2) Host compound The host compound used in the present invention is a compound mainly responsible for injecting and transporting charges in the light emitting layer, and emission of light itself is not substantially observed in the organic EL device.
Among the compounds contained in the light emitting layer, the host compound preferably has a mass ratio of 20% or more in the layer.
The host compounds may be used alone or in combination of two or more. By using a plurality of types of host compounds, it is possible to adjust the transfer of charges and improve the efficiency of the organic electroluminescence device.
The host compound preferably used in the present invention is described below.

As the host compound, the π-conjugated compound used in the present invention may be used as described above, but there is no particular limitation. From the viewpoint of reverse energy transfer is preferably one having a larger excitation energy than the excited singlet energy of the dopant, and more preferably even more with a large triplet energy than triplet energy of the dopant.
The host compound is responsible for transporting carriers and generating excitons in the light emitting layer. Therefore, cation radical state, anion radical state, and can exist stably in the state of all active species of the excited state, does not cause chemical changes such as decomposition and addition reactions, further, the host molecule in the layer over time with electricity It is preferable not to move at the Angstrom level.

Further, especially when the light emitting dopant in combination exhibits TADF emission, since long dwell time of the triplet excited state of the TADF compound, the higher the T ₁ energy level of the host compound itself, further host compound each other association that in a state not to create a low T ₁ state, that the TADF compound and the host compound does not form a exciplex, such that the host compound does not form a electro-mer by the electric field, molecules such as the host compound does not lower T ₁ of Proper design of the structure is required.
In order to meet these requirements, the host compound itself must have high electron hopping mobility, high hole hopping mobility, and a small structural change in the triplet excited state. Is. Typical examples of host compounds satisfying such requirements include those having a high T ₁ energy level such as a carbazole skeleton, an azacarbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton or an azadibenzofuran skeleton.

In addition, the host compound has a hole transporting ability or an electron transporting ability, prevents the emission of light having a long wavelength, and is stable against heat generation when the organic electroluminescence element is driven at a high temperature or while the element is driven. From the viewpoint of operating as described above, it is preferable to have a high glass transition temperature (Tg). The Tg is preferably 90°C or higher, more preferably 120°C or higher.
Here, the glass transition point (Tg) is a value determined by a method according to JIS K 7121-2012 using DSC (Differential Scanning Colorimetry).

Moreover, as the host compound used in the present invention, it is also preferable to use the π-conjugated compound according to the present invention as described above. The π-conjugated compound according to the present invention has a high T ₁ , and can be suitably used for a light emitting material having a short emission wavelength (that is, a high energy level of T ₁ and S ₁ ). Is.

When a known host compound is used in the organic EL device of the present invention, specific examples thereof include the compounds described in the following documents, but the present invention is not limited thereto.
JP-A-2001-257076, JP-A-2002-308855, JP-A-2001-313179, JP-A-2002-319491, JP-A-2001-357977, JP-A-2002-334786, and JP-A-2002-8860, No. 2002-334787, No. 2002-15871, No. 2002-334788, No. 2002-43056, No. 2002-334789, No. 2002-75645, No. 2002-338579, No. No. 2002-105445, No. 2002-343568, No. 2002-141173, No. 2002-352957, No. 2002-203683, No. 2002-363227, No. 2002-231453, No. 2003. No. 3165, No. 2002-234888, No. 2003-27048, No. 2002-255934, No. 2002-260861, No. 2002-280183, No. 2002-299060, No. 2002. No. 302516, No. 2002-305083, No. 2002-305084, No. 2002-308837, U.S. Patent Publication No. 20030175553, U.S. Patent Publication No. 20060280965, U.S. Patent Publication No. 20050112407, U.S. Patent Publication No. 20090017330, U.S. Patent Publication No. 20090030202, U.S. Patent Publication No. 200502389919, International Publication No. 2001039234, International Publication No. 20090221126, International Publication No. 2008056746, International Publication No. 2004093207, International Publication No. 2005089025, International Publication No. 2007063796, International Publication No. 2007703754, International Publication No. 2004107822, International Publication No. 2005030900, International Publication No. 2006149666, International Publication No. 2009086028, International Publication No. 2009003898, International Publication No. 2012023947, JP2008-074939A. No. 2007-254297, EP2034538, International Publication No. 20110559933, International Publication No. 2012035853, Japanese Patent Application Publication No. 2015-38941, and the like. Examples of the host compound described in JP-A-2015-38941 include compounds H-1 to H-230 described in [0255] to [0293] of the specification.
Specific examples of the compound used as the host compound in the present invention are shown below, but the host compound is not limited thereto.

上記一般式（Ｉ）中、Ｘ_１０１は、ＮＲ_１０１、酸素原子、硫黄原子、スルフィニル基、スルホニル基、ＣＲ_１０２Ｒ_１０３又はＳｉＲ_１０４Ｒ_１０５を表す。また、ｙ_１〜ｙ_８は、それぞれ独立に、ＣＲ_１０６、又は窒素原子を表す。ここで、Ｒ_１０１〜Ｒ_１０６は、それぞれ独立に、水素原子又は置換基を表し、互いに結合して環を形成してもよい。Ｒ_１０１〜Ｒ_１０６でありうる置換基の例には、以下の基が含まれる。 Furthermore, the host compound used in the present invention is preferably a compound represented by the following general formula (I). The compound represented by the following general formula (I) has a bipolar property and is very stable. Therefore, when the host compound is a compound represented by the following general formula (I), the life of the organic EL device tends to be long.

In the above general formula (I), X ₁₀₁ represents NR ₁₀₁ , oxygen atom, sulfur atom, sulfinyl group, sulfonyl group, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₄ R ₁₀₅ . In addition, y _{1 to} y ₈ each independently represent CR ₁₀₆ or a nitrogen atom. Here, R _{101 to} R ₁₀₆ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring. Examples of the substituent that may be R _{101 to} R ₁₀₆ include the following groups.

Linear or branched alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc. );
An alkenyl group (eg, vinyl group, allyl group, etc.);
An alkynyl group (eg, ethynyl group, propargyl group, etc.);
Aromatic hydrocarbon ring group (also referred to as aromatic carbocyclic group, aryl group, etc., for example, benzene ring, biphenyl, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene Ring, o-terphenyl ring, m-terphenyl ring, p-terphenyl ring, acenaphthene ring, coronene ring, indene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphene ring, picene Ring, pyrene ring, pyrantrene ring, anthraanthrene ring, group derived from tetralin, etc.);
Aromatic heterocyclic group (for example, furan ring, dibenzofuran ring, thiophene ring, dibenzothiophene ring, oxazole ring, pyrrole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring , Triazole ring, imidazole ring, pyrazole ring, thiazole ring, indole ring, indazole ring, benzimidazole ring, benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, cinnoline ring, quinoline ring, isoquinoline ring, phthalazine ring, naphthyridine Ring, carbazole ring, carboline ring, diazacarbazole ring (a group derived from a ring in which one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom, etc.). The carbazole ring may be collectively referred to as "azacarbazole ring".);
Non-aromatic hydrocarbon ring group (for example, cyclopentyl group, cyclohexyl group, etc.);
Non-aromatic heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.);
Alkoxy groups (eg, methoxy, ethoxy, propyloxy, pentyloxy, hexyloxy, octyloxy, dodecyloxy, etc.);
A cycloalkoxy group (for example, a cyclopentyloxy group, a cyclohexyloxy group, etc.);
Aryloxy groups (eg, phenoxy group, naphthyloxy group, etc.);
Alkylthio group (eg, methylthio group, ethylthio group, propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.);
Cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.);
Arylthio group (eg, phenylthio group, naphthylthio group, etc.):
Alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.);
Aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.);
Sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl group, naphthyl Aminosulfonyl group, 2-pyridylaminosulfonyl group, etc.);
Acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc. );
An acyloxy group (eg, acetyloxy group, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.);
Amido group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group) Groups, phenylcarbonylamino groups, naphthylcarbonylamino groups, etc.);
Carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group , Phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.);
Ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.);
Sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.);
An alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.);
Arylsulfonyl group or heteroarylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.);
Amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, diphenylamino group, etc. );
Halogen atom (eg, fluorine atom, chlorine atom, bromine atom, etc.);
Fluorohydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.);
Cyano group;
Nitro group;
Hydroxy group;
Thiol group;
A silyl group (eg, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.);
Deuterium atom

Among the above groups, preferable groups include linear or branched alkyl groups, aromatic hydrocarbon ring groups, aromatic heterocyclic groups, amino groups, fluorine atoms, fluorohydrocarbon groups, cyano groups, and silyl groups.

In addition, Ar ₁₀₁ and Ar ₁₀₂ each independently represent an optionally substituted aryl group or an optionally substituted heteroaryl group. The aryl group in the "optionally substituted aryl group" is preferably a group derived from an aromatic hydrocarbon ring having 6 to 24 carbon atoms. Examples of such aromatic hydrocarbon rings include benzene ring, indene ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, acenaphthylene ring, biphenylene ring, naphthacene ring, pyrene ring, pentalene ring, acean ring. Tolylene ring, heptalene ring, triphenylene ring, as-indacene ring, chrysene ring, s-indacene ring, pleiadene ring, phenalene ring, fluoranthene ring, perylene ring, acephenanthrylene ring, biphenyl ring, terphenyl ring, and A tetraphenyl ring and the like are included. Of these, a benzene ring, a biphenyl ring and a terphenyl ring are preferable.

Further, the heteroaryl group in the “optionally substituted heteroaryl group” is preferably a group derived from various aromatic heterocycles. Examples of such aromatic heterocycles include pyrrole ring, indole ring, carbazole ring, indoloindole ring, 9,10-dihydroacridine ring, 5,10-dihydrophenazine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring. Ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, azacarbazole ring, azadibenzofuran ring, dia Zacarbazole ring, diazadibenzofuran ring, dibenzothiophene oxide ring, dibenzothiophene dioxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, cinnoline ring, quinoxaline ring, A phthalazine ring, a pteridine ring, a phenanthridine ring, a phenanthroline ring, a dibenzofuran ring, a dibenzosilole ring, a dibenzoborol ring, a dibenzophosphole oxide ring and the like are included. Preferred are a carbazole ring, a benzocarbazole ring, an azacarbazole ring, an azadibenzofuran ring, a diazacarbazole ring, a diazadibenzofuran ring, a pyridine ring, a pyrimidine ring and a triazine ring.

Examples of the substituent which the aryl group or heteroaryl group may have include an aryl group which may be substituted with an alkyl group, a fluorine atom, a cyano group, an alkyl group which may be substituted with a fluorine atom, and a substituted group. Optionally carbonyl group, optionally substituted sulfonyl group, optionally substituted phosphine oxide group, optionally substituted boryl group, optionally substituted heterocyclic group, optionally substituted amino Groups, optionally substituted silyl groups, and the like are included. The "alkyl group" may be linear, branched or cyclic, and is, for example, a linear or branched alkyl group having 1 to 20 carbon atoms or a cyclic alkyl group having 5 to 20 carbon atoms. It is possible. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, cyclohexyl group. Group, 2-ethylhexyl group, n-heptyl group, n-octyl group, 2-hexyloctyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n- A tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, an n-icosyl group and the like are included. The “aryl group” and “heterocyclic group” may be the same as the aryl group or heteroaryl group represented by Ar ₁₀₁ and Ar ₁₀₂ .

In addition, in the above general formula (I), n101 and n102 each represent an integer of 0 to 4, but when R ₁₀₁ is a hydrogen atom, n101 represents an integer of 1 to 4.

一般式（II）において、Ｘ_１０１は、ＮＲ_１０１、酸素原子、硫黄原子、スルフィニル基、スルホニル基、ＣＲ_１０２Ｒ_１０３又はＳｉＲ_１０４Ｒ_１０５を表す。Ｒ_１０１〜Ｒ_１０５は、それぞれ独立して水素原子又は置換基を表し、互いに結合して環を形成してもよい。なお、Ｒ_１０１〜Ｒ_１０５は、一般式（Ｉ）のＲ_１０１〜Ｒ_１０５と同義である。 The host compound having the structure represented by the general formula (I) more preferably has the structure represented by the following general formula (II).

In the general formula (II), X ₁₀₁ represents NR ₁₀₁ , oxygen atom, sulfur atom, sulfinyl group, sulfonyl group, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₄ R ₁₀₅ . R _{101 to} R ₁₀₅ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring. In addition, R< ₁₀₁ >-R< ₁₀₅ > is synonymous with R< ₁₀₁ >-R< ₁₀₅ > of general formula (I).

Ar ₁₀₁ and _{Ar 102} are independently an optionally substituted aryl group, an heteroaryl group which may be _{substituted, Ar 101} and _{Ar 102} are _{Ar 101} and _{Ar 102} in Formula (I) Is synonymous with.

Further, n102 represents an integer of 0 to 4.

Further, the compound represented by the general formula (II) is preferably a compound represented by the following general formula (III-1), (III-2) or (III-3).

In the general formula (III-1) ~ (III -3), X 101, Ar 102, n102 have the same meanings as _{X 101,} Ar 102, n102 in the general formula (II). In the general formula _{(III-2), R 104} has the same meaning as _{R 104} in formula (I).
In the general formulas (III-1) to (III-3), the condensed ring, carbazole ring and benzene ring formed by including X ₁₀₁ may further have a substituent as long as the function of the host compound is not impaired. Good.

Specific preferred examples of the host compounds represented by the above general formulas (I), (II), or (III-1) to (III-3) will be given. These compounds may further have a substituent, There are cases where structural isomers and the like may exist, and the present invention is not limited to this description.

<Electron transport layer>
In the present invention, the electron transport layer is made of a material having a function of transporting electrons, and may have a function of transmitting the electrons injected from the cathode to the light emitting layer.
The total thickness of the electron transport layer according to the present invention is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably 2 to 500 nm, further preferably 5 to 200 nm.
Further, in the organic EL element, when the light generated in the light emitting layer is extracted from the electrode, the light directly extracted from the light emitting layer interferes with the light extracted after being reflected by the electrode that is opposite to the light extracting electrode. It is known to wake up. When the light is reflected by the cathode, it is possible to efficiently use this interference effect by appropriately adjusting the total layer thickness of the electron transport layer within a range of several nm to several μm.
On the other hand, when the layer thickness of the electron transport layer is increased, the voltage is likely to increase. Therefore, especially when the layer thickness is large, the electron mobility of the electron transport layer is preferably 10 ⁻⁵ cm ² /Vs or more. ..
The material used for the electron transporting layer (hereinafter referred to as electron transporting material) may have any of an electron injecting property, a transporting property, and a hole blocking property, and is arbitrarily selected from conventionally known compounds. Those selected can be used.

For example, nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more of the carbon atoms constituting the carbazole ring are substituted with nitrogen atoms), pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, pyridazine derivatives, Triazine derivative, quinoline derivative, quinoxaline derivative, phenanthroline derivative, azatriphenylene derivative, oxazole derivative, thiazole derivative, oxadiazole derivative, thiadiazole derivative, triazole derivative, benzimidazole derivative, benzoxazole derivative, benzthiazole derivative, etc.), dibenzofuran derivative, Examples thereof include dibenzothiophene derivatives, silole derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene derivatives, etc.).

Further, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, for example, tris(8-quinolinol)aluminum (Alq), tris(5,7-dichloro-8-quinolinol)aluminum, tris(5,7- Dibromo-8-quinolinol)aluminum, tris(2-methyl-8-quinolinol)aluminum, tris(5-methyl-8-quinolinol)aluminum, bis(8-quinolinol)zinc (Znq), and the like, and metal complexes thereof. A metal complex in which the central metal is replaced with In, Mg, Cu, Ca, Sn, Ga or Pb can also be used as the electron transport material.
In addition, metal-free or metal phthalocyanine, or those whose terminal is substituted with an alkyl group, a sulfonic acid group, or the like can be preferably used as the electron transport material. Further, the distyrylpyrazine derivatives exemplified as the material for the light emitting layer can also be used as the electron transport material, and like the hole injection layer and the hole transport layer, an inorganic semiconductor such as n-type-Si or n-type-SiC. Can also be used as an electron transport material.
Further, a polymer material obtained by introducing these materials into a polymer chain or using these materials as a polymer main chain can also be used.

In the electron transport layer according to the present invention, the electron transport layer may be doped with a dopant as a guest material to form an electron transport layer having a high n property (electron rich). Examples of the doping material include n-type dopants such as metal compounds such as metal complexes and metal halides. Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175 and J. Appl. Phys. , 95, 5773 (2004) and the like.

Specific examples of known preferable electron transporting materials used in the organic EL device of the present invention include compounds described in the following documents, but the present invention is not limited thereto.
United States Patent No. 6528187, United States Patent No. 7230107, United States Patent Application Publication No. 2005/0025993, United States Patent Application Publication No. 2004/0036077, United States Patent Application Publication No. 2009/0115316, United States Patent Published application 2009/0101870, Published US patent application 2009/0179554, Published international application 2003/060956, Published international application 2008/132085, Appl. Phys. Lett. 75, 4 (1999), Appl. Phys. Lett. 79,449 (2001), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 81, 162 (2002), Appl. Phys. Lett. 79,156 (2001), U.S. Patent No. 7,964,293, U.S. Patent Application Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387, International. Publication No. 2006/067931, International Publication No. 2007/086552, International Publication No. 2008/114690, International Publication No. 2009/069482, International Publication No. 2009/066779, International Publication No. 2009/054253, International Publication No. 2011/086935, International Publication No. 2010/150593, International Publication No. 2010/047707, European Patent No. 2311826, JP 2010-251675 A, JP 2009-209133 A, JP 2009-124114 A. JP-A-2008-277810, JP-A-2006-156445, JP-A-2005-340122, JP-A-2003-45662, JP-A-2003-31367, and JP-A-2003-228270. , International Publication No. 2012/115034 and the like.

More preferable known electron transporting materials in the present invention include aromatic heterocyclic compounds containing at least one nitrogen atom and compounds containing a phosphorus atom, such as pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives and dibenzofuran. Examples thereof include derivatives, dibenzothiophene derivatives, azadibenzofuran derivatives, azadibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, benzimidazole derivatives and arylphosphine oxide derivatives.
The electron transport material may be used alone or in combination of two or more kinds.

<Hole blocking layer>
The hole blocking layer is a layer having a function of an electron transporting layer in a broad sense, and is preferably made of a material having a function of transporting an electron and a small ability to transport a hole. By blocking the above, the recombination probability of electrons and holes can be improved.
Further, the structure of the electron transport layer described above can be used as the hole blocking layer according to the present invention, if necessary.
The hole blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the cathode side of the light emitting layer.
The layer thickness of the hole blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably 5 to 30 nm.
As the material used for the hole blocking layer, the material used for the electron transport layer described above is preferably used, and the material used as the host compound described above is also preferably used for the hole blocking layer.

<Electron injection layer>
The electron injection layer (also referred to as “cathode buffer layer”) according to the present invention is a layer provided between the cathode and the light emitting layer in order to reduce the driving voltage and improve the light emission brightness. It is described in detail in Chapter 2, "Electrode Materials" (Pages 123 to 166), Volume 2, "Forefront of Industrialization" (published on Nov. 30, 1998, NTS Co., Ltd.).
In the present invention, the electron injection layer may be provided as necessary and may be present between the cathode and the light emitting layer or between the cathode and the electron transport layer as described above.
The electron injection layer is preferably a very thin film, and the layer thickness is preferably in the range of 0.1 to 5 nm, although it depends on the material. Further, it may be a non-uniform layer (film) in which the constituent material is present intermittently.

Details of the electron injection layer are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specific examples of materials preferably used for the electron injection layer are as follows. , Metals such as strontium and aluminum, alkali metal compounds such as lithium fluoride, sodium fluoride and potassium fluoride, alkaline earth metal compounds such as magnesium fluoride and calcium fluoride, oxidation Examples thereof include metal oxides typified by aluminum, metal complexes typified by lithium 8-hydroxyquinolinate (Liq), and the like. It is also possible to use the above-mentioned electron transport material.
The materials used for the electron injection layer may be used alone or in combination of two or more.

<Hole transport layer>
In the present invention, the hole transport layer is made of a material having a function of transporting holes, and may have a function of transmitting the holes injected from the anode to the light emitting layer.
The total thickness of the hole transport layer according to the present invention is not particularly limited, but is usually in the range of 5 nm to 5 μm, more preferably 2 to 500 nm, further preferably 5 to 200 nm.
The material used for the hole-transporting layer (hereinafter referred to as the hole-transporting material) may have any of the hole-injecting or transporting property and the electron-blocking property. Any of these can be selected and used.
For example, porphyrin derivative, phthalocyanine derivative, oxazole derivative, oxadiazole derivative, triazole derivative, imidazole derivative, pyrazoline derivative, pyrazolone derivative, phenylenediamine derivative, hydrazone derivative, stilbene derivative, polyarylalkane derivative, triarylamine derivative, carbazole derivative. , Indolocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polyvinylcarbazole, polymer materials or oligomers containing aromatic amines introduced in the main chain or side chains, polysilane, conductive Polymers or oligomers (for example, PEDOT/PSS, aniline-based copolymers, polyaniline, polythiophene, etc.) and the like can be mentioned.

Examples of triarylamine derivatives include benzidine type compounds represented by α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) and starburst type compounds represented by MTDATA. Examples thereof include compounds having fluorene or anthracene in the triarylamine-linked core portion.
Further, a hexaazatriphenylene derivative as described in JP-B-2003-515432, JP-A-2006-135145, etc. can be similarly used as the hole transport material.
Further, a hole transport layer having a high p property doped with impurities can be used. Examples thereof include JP-A-4-297076, JP-A-2000-196140, and JP-A-2001-102175, and J. Appl. Phys. , 95, 5773 (2004) and the like.

Further, JP-A No. 11-251067, J. Huang et. al. It is also possible to use a so-called p-type hole transporting material or an inorganic compound such as p-type-Si or p-type-SiC as described in the literature (Applied Physics Letters 80 (2002), p.139). Furthermore, an orthometalated organometallic complex having Ir or Pt as a central metal represented by Ir(ppy)3 is also preferably used.
As the hole transport material, the above materials can be used, but a triarylamine derivative, a carbazole derivative, an indolocarbazole derivative, an azatriphenylene derivative, an organometallic complex, and an aromatic amine are introduced into the main chain or side chains. The polymer materials or oligomers mentioned above are preferably used.

Specific examples of known preferable hole transport materials used in the organic EL device of the present invention include the compounds described in the following documents in addition to the above-mentioned documents, but the present invention is not limited thereto. Not done.
For example, Appl. Phys. Lett. 69, 2160 (1996), J. Lumin. 72-74, 985 (1997), Appl. Phys. Lett. 78, 673 (2001), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 90, 183503 (2007), Appl. Phys. Lett. 51, 913 (1987), Synth. Met. 87,171 (1997), Synth. Met. 91, 209 (1997), Synth. Met. 111, 421 (2000), SID Symposium Digest, 37, 923 (2006), J. Am. Mater. Chem. 3, 319 (1993), Adv. Mater. 6,677 (1994), Chem. Mater. 15, 3148 (2003), U.S. Patent Application Publication No. 2003/0162053, U.S. Patent Application Publication No. 2002/0158242, U.S. Patent Application Publication No. 2006/0240279, U.S. Patent Application Publication No. 2008/. No. 0220265, U.S. Pat. Description, U.S. Patent Application Publication No. 2008/0106190, U.S. Patent Application Publication No. 2008/0018221, International Publication No. 2012/115034, Japanese Patent Publication No. 2003-159432, Japanese Patent Laid-Open No. 2006-135145. U.S. Patent Application No. 13/585981 and the like.
The hole transport material may be used alone or in combination of two or more kinds.

<Electron blocking layer>
The electron blocking layer is a layer having a function of a hole transporting layer in a broad sense, and is preferably made of a material having a function of transporting holes and having a small ability to transport electrons, while transporting holes. By blocking the electrons, the recombination probability of electrons and holes can be improved.
Further, the structure of the hole transport layer described above can be used as the electron blocking layer according to the present invention, if necessary.
The electron blocking layer provided in the organic EL device of the present invention is preferably provided adjacent to the anode side of the light emitting layer.
The layer thickness of the electron blocking layer according to the present invention is preferably in the range of 3 to 100 nm, more preferably 5 to 30 nm.
As the material used for the electron blocking layer, the materials used for the hole transport layer described above are preferably used, and the host compounds described above are also preferably used for the electron blocking layer.

<Hole injection layer>
The hole injection layer (also referred to as “anode buffer layer”) according to the present invention is a layer provided between the anode and the light emitting layer for lowering the driving voltage and improving the light emission brightness. It is described in detail in Chapter 2, “Electrode Materials” (Pages 123 to 166), Volume 2, “Forefront of Industrialization” (published on Nov. 30, 1998, NTS Co., Ltd.).
In the present invention, the hole injection layer may be provided as necessary and may be present between the anode and the light emitting layer or between the anode and the hole transport layer as described above.
The hole injection layer is described in detail in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like, and examples of materials used for the hole injection layer include: Examples thereof include the materials used for the hole transport layer.
Among them, a phthalocyanine derivative typified by copper phthalocyanine, a hexaazatriphenylene derivative as described in JP 2003-515432 A, JP 2006-135145 A, a metal oxide typified by vanadium oxide, or an amorphous carbon. Conductive polymers such as polyaniline (emeraldine) and polythiophene, orthometallated complexes represented by tris(2-phenylpyridine)iridium complex, triarylamine derivatives and the like are preferable.
The above-mentioned materials used for the hole injection layer may be used alone or in combination of two or more.

"Additive"
The organic layer in the present invention described above may further contain other additives.
Examples of the additives include halogen elements such as bromine, iodine and chlorine and halogenated compounds, alkali metals and alkaline earth metals such as Pd, Ca and Na, compounds and complexes of transition metals, salts and the like.
The content of the additive can be arbitrarily determined, but it is preferably 1000 ppm or less, more preferably 500 ppm or less, and further preferably 50 ppm or less based on the total mass% of the layer to be contained. .
However, it is not within this range depending on the purpose of improving the transportability of electrons and holes and the purpose of making energy transfer of excitons advantageous.

<Method of forming organic layer>
A method for forming the organic layer (hole injection layer, hole transport layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, intermediate layer, etc.) according to the present invention will be described.
The method for forming the organic layer according to the present invention is not particularly limited, and a conventionally known method such as a vacuum deposition method or a wet method (also referred to as a wet process) can be used.
As the wet method, there are spin coating method, casting method, ink jet method, printing method, die coating method, blade coating method, roll coating method, spray coating method, curtain coating method, LB method (Langmuir-Blodgett method) and the like. From the viewpoint of easy production of a uniform thin film and high productivity, a roll-to-roll method having high suitability such as a die coating method, a roll coating method, an ink jet method, and a spray coating method is preferable.

As a liquid medium for dissolving or dispersing the organic EL material used in the present invention, for example, methyl ethyl ketone, ketones such as cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene, Aromatic hydrocarbons such as mesitylene and cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used.
As the dispersion method, it is possible to disperse by a dispersion method such as ultrasonic wave, high shearing force dispersion or media dispersion.
Further, a different film forming method may be applied to each layer. When a vapor deposition method is adopted for film formation, the vapor deposition conditions vary depending on the type of compound used and the like, but generally, the boat heating temperature is 50 to 450° C., the vacuum degree is 10 ⁻⁶ to 10 ⁻² Pa, the vapor deposition rate is 0.01 to 50 nm/sec, substrate temperature −50 to 300° C., layer (film) thickness 0.1 nm to 5 μm, preferably 5 to 200 nm are appropriately selected.
In forming the organic layer according to the present invention, it is preferable to consistently form from the hole injection layer to the cathode by vacuuming once, but it is also possible to take out in the middle and apply a different film forming method. In that case, it is preferable to carry out the work in a dry inert gas atmosphere.

"anode"
As the anode in the organic EL element, a material having a high work function (4 eV or more, preferably 4.5 eV or more), an alloy, an electrically conductive compound, or a mixture thereof as an electrode substance is preferably used. Specific examples of such an electrode substance include a conductive transparent material such as a metal such as Au, CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. Alternatively, a material such as IDIXO (In ₂ O ₃ —ZnO) that can form an amorphous transparent conductive film may be used.
The anode may be formed into a thin film by a method such as vapor deposition or sputtering of these electrode substances, and a pattern of a desired shape may be formed by a photolithography method, or when pattern accuracy is not required so much (about 100 μm or more). Alternatively, a pattern may be formed through a mask having a desired shape during vapor deposition or sputtering of the electrode material.
Alternatively, when a coatable substance such as an organic conductive compound is used, a wet film forming method such as a printing method or a coating method can be used. When the emitted light is taken out from this anode, it is desirable that the transmittance is higher than 10%, and the sheet resistance as the anode is preferably several hundred Ω/□ or less.
Although the thickness of the anode depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm.

"cathode"
As the cathode, a metal having a low work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound, or a mixture thereof is used as an electrode material. Specific examples of such an electrode material include sodium, sodium-potassium alloy, magnesium, lithium, magnesium/copper mixture, magnesium/silver mixture, magnesium/aluminum mixture, magnesium/indium mixture, aluminum/aluminum oxide (Al ₂ O 3 ). ₃ ) Mixtures, indium, lithium/aluminum mixtures, aluminum, rare earth metals and the like. Among these, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function than that of the electron injecting metal, for example, a magnesium/silver mixture, from the viewpoint of electron injecting property and durability against oxidation and the like. A magnesium/aluminum mixture, a magnesium/indium mixture, an aluminum/aluminum oxide (Al ₂ O ₃ ) mixture, a lithium/aluminum mixture, aluminum and the like are suitable.

The cathode can be produced by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. The sheet resistance of the cathode is preferably several hundred Ω/□ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.
Since the emitted light is transmitted, if either the anode or the cathode of the organic EL element is transparent or semi-transparent, the emission brightness is improved, which is convenient.
In addition, a transparent or semitransparent cathode can be produced by producing the above-mentioned metal in a thickness of 1 to 20 nm on the cathode and then producing the conductive transparent material mentioned in the description of the anode thereon. By applying, it is possible to fabricate a device in which both the anode and the cathode are transparent.

[Supporting substrate]
The supporting substrate (hereinafter, also referred to as a substrate, a base material, etc.) that can be used in the organic EL device of the present invention is not particularly limited in the kind of glass, plastic, etc., and is transparent or opaque. May be. When extracting light from the supporting substrate side, the supporting substrate is preferably transparent. Examples of transparent support substrates that are preferably used include glass, quartz, and transparent resin films. A particularly preferable support substrate is a resin film that can give flexibility to the organic EL element.

Examples of the resin film include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate ( CAP), cellulose acetate phthalate, cellulose esters such as cellulose nitrate or derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate, norbornene resin, polymethylpentene, polyether ketone, polyimide , Polyethersulfone (PES), Polyphenylene sulfide, Polysulfones, Polyetherimide, Polyetherketone imide, Polyamide, Fluoropolymer, Nylon, Polymethylmethacrylate, Acrylic or polyarylate, Arton (product name JSR) or Apell (Trade name, manufactured by Mitsui Chemicals, Inc.) and the like.

On the surface of the resin film, an inorganic film, an organic film, or a hybrid film of both of them may be formed, and the water vapor permeability (25±0.5° C.) measured by a method according to JIS K 7129-1992 , Relative humidity (90±2)% RH) is preferably a barrier film having a relative humidity of 0.01 g/m ² ·24 h or less, and further, oxygen permeability measured by a method according to JIS K 7126-1987. Is preferably 1×10 ⁻³ ml/m ² ·24 h·atm or less and a water vapor permeability of 1×10 ⁻⁵ g/m ² ·24 h or less, which is a high barrier film.

As a material for forming the barrier film, any material may be used as long as it has a function of suppressing entry of moisture or oxygen, which causes deterioration of the element, and examples thereof include silicon oxide, silicon dioxide, and silicon nitride. Further, in order to improve the brittleness of the film, it is more preferable to have a laminated structure of these inorganic layers and layers made of an organic material. The order of stacking the inorganic layer and the organic layer is not particularly limited, but it is preferable to alternately stack the plurality of layers.
The method for forming the barrier film is not particularly limited, and examples thereof include vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, atmospheric pressure plasma polymerization method. The plasma CVD method, the laser CVD method, the thermal CVD method, the coating method and the like can be used, but the atmospheric pressure plasma polymerization method as described in JP 2004-68143 A is particularly preferable.

Examples of the opaque support substrate include metal plates such as aluminum and stainless steel, films and opaque resin substrates, and ceramic substrates.
The external extraction quantum efficiency of light emission of the organic EL device of the present invention at room temperature (25° C.) is preferably 1% or more, and more preferably 5% or more.
Here, the external extraction quantum efficiency (%)=the number of photons emitted outside the organic EL element/the number of electrons flown into the organic EL element×100.
Further, a hue improving filter such as a color filter or the like may be used together, or a color conversion filter that converts the emission color from the organic EL element into multiple colors by using a phosphor may be used together.

[Sealing]
Examples of the sealing means used for sealing the organic EL element of the present invention include a method of adhering a sealing member, an electrode, and a support substrate with an adhesive. The sealing member may be arranged so as to cover the display area of the organic EL element, and may have a concave plate shape or a flat plate shape. Moreover, the transparency and the electrical insulation are not particularly limited.
Specific examples include a glass plate, a polymer plate/film, a metal plate/film, and the like. Examples of the glass plate include soda lime glass, barium/strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like. Examples of the metal plate include those made of one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium and tantalum.

In the present invention, a polymer film or a metal film can be preferably used because the organic EL device can be made thin. Further, the polymer film has an oxygen permeability of 1×10 ⁻³ ml/m ² ·24 h or less measured by a method according to JIS K 7126-1987, and a method according to JIS K 7129-1992. The water vapor permeability (25±0.5° C., relative humidity 90±2%) is preferably 1×10 ⁻³ g/m ² ·24 h or less.
Sandblasting, chemical etching or the like is used to process the sealing member into a concave shape.

Specific examples of the adhesive include photocurable and thermosetting adhesives having a reactive vinyl group of acrylic acid-based oligomer and methacrylic acid-based oligomer, and moisture-curable adhesives such as 2-cyanoacrylic acid ester. be able to. In addition, epoxy and other heat and chemical curing types (mixing of two liquids) can be used. Moreover, hot-melt type polyamide, polyester, and polyolefin can be mentioned. Further, a cation-curing type UV-curing type epoxy resin adhesive can be mentioned.
Since the organic EL element may be deteriorated by heat treatment, it is preferable that the adhesive can be cured from room temperature to 80°C. A desiccant may be dispersed in the adhesive. The adhesive may be applied to the sealing portion using a commercially available dispenser or may be printed by screen printing.

Further, it is also preferable that the electrode and the organic layer are covered on the outer side of the electrode on the side opposite to the supporting substrate with the organic layer sandwiched therebetween, and an inorganic or organic material layer is formed in contact with the supporting substrate to form a sealing film. . In this case, the material for forming the film may be any material that has a function of suppressing the intrusion of water or oxygen, which causes deterioration of the element, such as silicon oxide, silicon dioxide, and silicon nitride. it can.
Further, in order to improve the brittleness of the film, it is preferable to have a laminated structure of these inorganic layers and a layer made of an organic material. The method for forming these films is not particularly limited, and examples thereof include vacuum deposition method, sputtering method, reactive sputtering method, molecular beam epitaxy method, cluster ion beam method, ion plating method, plasma polymerization method, and atmospheric pressure plasma heavy. A legal method, a plasma CVD method, a laser CVD method, a thermal CVD method, a coating method, or the like can be used.

In the gap between the sealing member and the display region of the organic EL element, an inert gas such as nitrogen or argon or an inert liquid such as fluorocarbon or silicon oil may be injected in the vapor phase and the liquid phase. preferable. A vacuum can also be used. Also, a hygroscopic compound can be enclosed inside.
Examples of the hygroscopic compound include metal oxides (eg, sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide, etc.), sulfates (eg, sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate). Etc.), metal halides (eg, calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), perchloric acids (eg, perchloric acid) Barium, magnesium perchlorate, etc.) and the like, and anhydrous salts are preferably used for sulfates, metal halides and perchloric acids.

[Protective film, protective plate]
A protective film or a protective plate may be provided outside the encapsulating film or the encapsulating film on the side facing the support substrate with the organic layer interposed therebetween in order to enhance the mechanical strength of the device. In particular, when the sealing is performed by the sealing film, its mechanical strength is not necessarily high, so that it is preferable to provide such a protective film or protective plate. As the material that can be used for this, the same glass plate, polymer plate/film, metal plate/film, etc. as those used for the above-mentioned encapsulation can be used, but the polymer film is lightweight and thin. Is preferably used.

[Light extraction improvement technology]
The organic EL element emits light inside a layer having a refractive index higher than air (refractive index within a range of about 1.6 to 2.1), and emits 15% to 20% of the light generated in the light emitting layer. It is generally said that it can only be taken out. This is because light incident on the interface (interface between the transparent substrate and air) at an angle θ equal to or greater than the critical angle causes total reflection and cannot be extracted to the outside of the device. This is because the light undergoes total internal reflection between them, and the light is guided through the transparent electrode or the light emitting layer, and as a result, the light escapes in the lateral direction of the element.

As a method for improving the efficiency of extracting light, for example, a method of forming irregularities on the surface of a transparent substrate to prevent total internal reflection at the interface between the transparent substrate and the air (for example, US Pat. No. 4,774,435), is used. A method of improving efficiency by providing light condensing property (for example, Japanese Patent Laid-Open No. 63-314795), a method of forming a reflecting surface on a side surface of an element (for example, Japanese Patent Laid-Open No. 1-220394), substrate And a light-emitting body by introducing a flat layer having an intermediate refractive index to form an antireflection film (for example, Japanese Patent Application Laid-Open No. 62-172691), and a lower refractive index than the substrate between the substrate and the light-emitting body. (For example, Japanese Patent Laid-Open No. 2001-202827), a method of forming a diffraction grating between any of the substrate, the transparent electrode layer, and the light emitting layer (including the substrate and the outside) ( JP-A No. 11-283751) and the like.

In the present invention, these methods can be used in combination with the organic EL device of the present invention. A method of forming a diffraction grating between any of the electrode layers and the light emitting layer (including between the substrate and the outside) can be preferably used.
In the present invention, by combining these means, it is possible to obtain an element having higher brightness or durability.

When a medium with a low refractive index is formed between the transparent electrode and the transparent substrate with a thickness that is longer than the wavelength of light, the light emitted from the transparent electrode has a higher extraction efficiency to the outside as the refractive index of the medium is lower. Become.
Examples of the low refractive index layer include aerogel, porous silica, magnesium fluoride, and fluoropolymer. Since the refractive index of the transparent substrate is generally within the range of about 1.5 to 1.7, the low refractive index layer preferably has a refractive index of about 1.5 or less. Further, it is preferably 1.35 or less.
Moreover, it is desirable that the thickness of the low-refractive-index medium be at least twice the wavelength in the medium. This is because when the thickness of the low-refractive-index medium becomes about the wavelength of light and the electromagnetic wave exuded by evanescent enters into the substrate, the effect of the low-refractive-index layer diminishes.

The method of introducing a diffraction grating into the interface that causes total internal reflection or into any one of the media is characterized by a high effect of improving the light extraction efficiency. This method uses the property that the diffraction grating can change the direction of light to a specific direction different from refraction by means of so-called Bragg diffraction such as first-order diffraction and second-order diffraction. The light that cannot go out due to total reflection between layers is diffracted by introducing a diffraction grating into any of the layers or into the medium (in the transparent substrate or transparent electrode). , Trying to get the light out.

The diffraction grating to be introduced preferably has a two-dimensional periodic refractive index. This is because the light emitted from the light emitting layer is randomly generated in all directions, so in a general one-dimensional diffraction grating that has a periodic refractive index distribution only in a certain direction, only the light traveling in a specific direction is diffracted. Therefore, the light extraction efficiency does not increase so much.
However, by making the refractive index distribution a two-dimensional distribution, light traveling in all directions is diffracted, and the light extraction efficiency is improved.
The position where the diffraction grating is introduced may be in any layer or in the medium (in the transparent substrate or in the transparent electrode), but is preferably near the organic light emitting layer where light is generated. At this time, the period of the diffraction grating is preferably in the range of about 1/2 to 3 times the wavelength of the light in the medium. The array of diffraction gratings is preferably a two-dimensional array such as a square lattice shape, a triangular lattice shape, or a honeycomb lattice shape.

[Condensing sheet]
The organic EL device of the present invention has a structure in which, for example, a structure on a microlens array is provided on the light extraction side of a supporting substrate (substrate), or by combining it with a so-called light-condensing sheet, the organic EL device is fronted in a specific direction, for example, the light emitting surface of the device. By converging in the direction, the brightness in the specific direction can be increased.
As an example of the microlens array, square pyramids having a side of 30 μm and an apex angle of 90 degrees are two-dimensionally arranged on the light extraction side of the substrate. One side is preferably in the range of 10 to 100 μm. If it is smaller than this, the effect of diffraction occurs and it is colored, and if it is too large, the thickness becomes thick, which is not preferable.
As the light-condensing sheet, it is possible to use, for example, one that has been put to practical use in an LED backlight of a liquid crystal display device. As such a sheet, for example, a brightness enhancement film (BEF) manufactured by Sumitomo 3M Limited can be used. As the shape of the prism sheet, for example, a Δ-shaped stripe having a vertical angle of 90° and a pitch of 50 μm may be formed on the base material, or the vertical angle may be rounded or the pitch may be changed randomly. It may have a different shape or another shape.
Further, a light diffusing plate/film may be used together with the light collecting sheet in order to control the light emission angle from the organic EL element. For example, a diffusion film (light up) manufactured by Kimoto Co., Ltd. can be used.

[Use]
The organic EL element of the present invention can be used as an electronic device such as a display device, a display, and various light emitting devices.
Examples of the light emitting device include lighting devices (home lighting, interior lighting), clocks and liquid crystal backlights, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, and light sources. Examples of the light source include a light source of a sensor, but the present invention is not limited to this. In particular, it can be effectively used for a backlight of a liquid crystal display device and a light source for illumination.
In the organic EL device of the present invention, patterning may be performed by a metal mask, an inkjet printing method, or the like at the time of film formation, if necessary. When patterning, only the electrode may be patterned, the electrode and the light emitting layer may be patterned, or the entire element layer may be patterned. In the fabrication of the element, a conventionally known method is used. You can

<Display device>
A display device including the organic EL element of the present invention may be monochromatic or polychromatic. Here, a multicolor display device will be described.

In the case of a multicolor display device, a shadow mask is provided only when the light emitting layer is formed, and the film can be formed on one surface by a vapor deposition method, a casting method, a spin coating method, an inkjet method, a printing method, or the like.
When patterning only the light emitting layer, the method is not limited, but vapor deposition method, ink jet method, spin coating method and printing method are preferable.

The configuration of the organic EL element included in the display device is selected from the above-described configuration examples of the organic EL element as needed.

The method for manufacturing the organic EL element is as shown in the above-described one aspect of manufacturing the organic EL element of the present invention.

When a direct current voltage is applied to the thus obtained multicolor display device, light emission can be observed by applying a voltage of about 2 to 40 V with the anode having a positive polarity and the cathode having a negative polarity. Further, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the − state. The waveform of the alternating current applied may be arbitrary.

The multicolor display device can be used as a display device, a display, or various light emitting light sources. In a display device or display, full-color display can be performed by using three types of organic EL elements that emit blue, red, and green light.

Examples of the display device or display include a television, a personal computer, a mobile device, an AV device, a teletext display, and an information display in a car. In particular, it may be used as a display device for reproducing a still image or a moving image, and a drive system for use as a display device for reproducing a moving image may be either a simple matrix (passive matrix) system or an active matrix system.

Light-emitting devices include home lighting, interior lighting, backlights for watches and liquid crystals, billboard advertisements, traffic lights, light sources for optical storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, etc. However, the present invention is not limited thereto.

Hereinafter, an example of a display device having the organic EL element of the present invention will be described with reference to the drawings.
FIG. 5 is a schematic diagram showing an example of a display device composed of organic EL elements. It is a schematic diagram of a display such as a mobile phone, which displays image information by light emission of an organic EL element.

The display 1 has a display section A having a plurality of pixels, a control section B that performs image scanning of the display section A based on image information, a wiring section C that electrically connects the display section A and the control section B, and the like.
The control unit B is electrically connected to the display unit A via the wiring unit C, sends a scanning signal and an image data signal to each of a plurality of pixels based on image information from the outside, and the pixels for each scanning line by the scanning signal. Emits light sequentially according to the image data signal to perform image scanning and display image information on the display unit A.

FIG. 6 is a schematic view of a display device of the active matrix system.
The display section A has a wiring section C including a plurality of scanning lines 5 and data lines 6 and a plurality of pixels 3 and the like on a substrate. The main members of the display unit A will be described below.
FIG. 6 shows a case where the light emitted from the pixel 3 is extracted in the direction of the white arrow (downward).

The scanning lines 5 and the plurality of data lines 6 of the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern and are connected to the pixels 3 at the orthogonal positions (details are shown in the drawings). Not).
When a scanning signal is applied from the scanning line 5, the pixel 3 receives an image data signal from the data line 6 and emits light according to the received image data.
Full-color display is possible by appropriately arranging pixels in the red color region, green color region, and blue color region on the same substrate.

Next, the light emitting process of the pixel will be described. FIG. 7 is a schematic diagram showing a pixel circuit.
The pixel includes an organic EL element 10, a switching transistor 11, a drive transistor 12, a capacitor 13 and the like. Full-color display can be performed by using red, green, and blue light-emitting organic EL elements as the organic EL elements 10 in a plurality of pixels and arranging them in parallel on the same substrate.

In FIG. 7, an image data signal is applied from the control unit B to the drain of the switching transistor 11 via the data line 6. Then, when a scanning signal is applied to the gate of the switching transistor 11 from the control unit B via the scanning line 5, the driving of the switching transistor 11 is turned on, and the image data signal applied to the drain is transferred to the capacitor 13 and the driving transistor 12. Is transmitted to the gate.

By transmitting the image data signal, the capacitor 13 is charged according to the potential of the image data signal, and the driving of the drive transistor 12 is turned on. The drive transistor 12 has a drain connected to the power supply line 7 and a source connected to the electrode of the organic EL element 10. The drive transistor 12 is connected from the power supply line 7 to the organic EL element 10 according to the potential of the image data signal applied to the gate. Electric current is supplied.

When the scanning signal is transferred to the next scanning line 5 by the sequential scanning of the control unit B, the driving of the switching transistor 11 is turned off. However, since the capacitor 13 holds the potential of the charged image data signal even if the switching transistor 11 is turned off, the driving transistor 12 is kept on and the next scanning signal is applied. The organic EL element 10 continues to emit light. When a scanning signal is applied next by sequential scanning, the driving transistor 12 is driven according to the potential of the next image data signal synchronized with the scanning signal, and the organic EL element 10 emits light.
That is, the light emission of the organic EL element 10 is such that the switching transistor 11 and the drive transistor 12 which are active elements are provided for the organic EL element 10 of each of the plurality of pixels, and the organic EL element 10 of each of the plurality of pixels 3 emits light. It is carried out. Such a light emitting method is called an active matrix method.

Here, the light emission of the organic EL element 10 may be light emission of a plurality of gradations according to a multivalued image data signal having a plurality of gradation potentials, or may be ON or OFF of a predetermined light emission amount according to a binary image data signal. Good. Further, the potential of the capacitor 13 may be held continuously until the next scanning signal is applied, or may be discharged immediately before the next scanning signal is applied.
The present invention is not limited to the above-mentioned active matrix system, but may be a passive matrix system light emission drive in which the organic EL element emits light according to the data signal only when the scanning signal is scanned.

FIG. 8 is a schematic view of a display device of a passive matrix system. In FIG. 8, a plurality of scanning lines 5 and a plurality of image data lines 6 are provided in a grid pattern so as to face each other with the pixel 3 interposed therebetween.
When the scanning signal of the scanning line 5 is applied by sequential scanning, the pixels 3 connected to the applied scanning line 5 emit light according to the image data signal.
In the passive matrix method, the pixel 3 has no active element, so that the manufacturing cost can be reduced.
By using the organic EL element of the present invention, a display device having improved luminous efficiency was obtained.

<Lighting device>
The organic EL element of the present invention can also be used in a lighting device.
The organic EL element of the present invention may be used as an organic EL element having a resonator structure. Examples of the purpose of using the organic EL element having such a resonator structure include a light source for an optical storage medium, a light source for an electrophotographic copying machine, a light source for an optical communication processor, a light source for an optical sensor, and the like. Not limited. Moreover, you may use it for the said use by making a laser oscillation.
Further, the organic EL element of the present invention may be used as a kind of lamp for illumination or an exposure light source, or may be a projection device of a type for projecting an image, or a type of type for directly visually recognizing a still image or a moving image. It may be used as a display device (display).
When used as a display device for reproducing moving images, either a passive matrix system or an active matrix system may be used as a drive system. Alternatively, a full-color display device can be manufactured by using two or more kinds of organic EL elements of the present invention having different emission colors.

In addition, the π-conjugated compound used in the present invention can be applied to a lighting device including an organic EL element that emits substantially white light. For example, when a plurality of light emitting materials are used, white light emission can be obtained by simultaneously emitting a plurality of light emitting colors and mixing the colors. As a combination of a plurality of emission colors, one containing three emission maximum wavelengths of three primary colors of red, green and blue may be used, or two combinations of complementary colors such as blue and yellow, blue green and orange may be used. It may contain a maximum emission wavelength.

Further, in the method for forming an organic EL device of the present invention, a mask is provided only when the light emitting layer, the hole transporting layer, the electron transporting layer and the like are formed, and the masks may be simply arranged such that they are separately coated. Since the other layers are common, patterning such as a mask is unnecessary, and for example, an electrode film can be formed on one surface by a vapor deposition method, a cast method, a spin coating method, an inkjet method, a printing method, or the like, and the productivity is improved.
According to this method, unlike a white organic EL device in which light emitting elements of a plurality of colors are arranged in parallel in an array, the element itself emits white light.

[One Embodiment of Illumination Device of the Present Invention]
One aspect of the lighting device of the present invention, which includes the organic EL element of the present invention, will be described.
The non-light-emitting surface of the organic EL device of the present invention is covered with a glass case, a glass substrate having a thickness of 300 μm is used as a sealing substrate, and an epoxy-based photocurable adhesive (Lux manufactured by Toagosei Co., Ltd. is used as a sealing material around the periphery. Track LC0629B) is applied, and this is stacked on the cathode and brought into close contact with the transparent supporting substrate, and UV light is irradiated from the glass substrate side to cure and seal the illumination as shown in FIGS. 9 and 10. A device can be formed.
FIG. 9 shows a schematic view of a lighting device. The organic EL element of the present invention (organic EL element 101 in the lighting device) is covered with a glass cover 102 (note that the sealing work with the glass cover is performed by lighting The organic EL element 101 in the apparatus was placed in a glove box (under an atmosphere of high-purity nitrogen gas having a purity of 99.999% or more) under a nitrogen atmosphere without contacting the atmosphere.
FIG. 10 is a cross-sectional view of the lighting device, in which 105 is a cathode, 106 is an organic layer, and 107 is a glass substrate with a transparent electrode. The glass cover 102 is filled with nitrogen gas 108 and is provided with a water catching agent 109.
By using the organic EL element of the present invention, a lighting device having improved luminous efficiency can be obtained.

<Light emitting material>
The π-conjugated compound of the present invention can emit fluorescence when excited by an electric field or the like. Therefore, it can be used as various light emitting materials. The luminescent material may contain other components, if necessary, in addition to the π-conjugated compound. Further, the light emitting material may be used in the form of powder, or may be processed into a desired shape for use. The luminescent material can be applied to, for example, a material for forming a luminescent thin film described later, a fluorescent paint, and a bioimaging fluorescent dye.

Further, if the absolute value of Delta] E _ST of [pi conjugated compound is less than 0.50eV, π-conjugated compounds, and can radiate delayed fluorescence, such compounds can be applied to bio-imaging fluorescent dyes You can Furthermore, since delayed fluorescence is known to be quenched by oxygen, it can also be applied to oxygen sensing materials.

<Light emitting thin film>
The luminescent thin film according to the present invention is characterized by containing the above-described π-conjugated compound according to the present invention, and can be produced in the same manner as the method for forming the organic layer.
The luminescent thin film and the luminescent thin film of the present invention can be produced in the same manner as the method for forming the organic layer.

The method for forming the luminescent thin film of the present invention is not particularly limited, and a conventionally known method such as a vacuum vapor deposition method or a wet method (also referred to as a wet process) can be used.
As the wet method, there are spin coating method, casting method, ink jet method, printing method, die coating method, blade coating method, roll coating method, spray coating method, curtain coating method, LB method (Langmuir-Blodgett method) and the like. From the viewpoint of easy production of a uniform thin film and high productivity, a roll-to-roll method having high suitability such as a die coating method, a roll coating method, an ink jet method, and a spray coating method is preferable.

Examples of the liquid medium for dissolving or dispersing the luminescent material used in the present invention include ketones such as methyl ethyl ketone and cyclohexanone, fatty acid esters such as ethyl acetate, halogenated hydrocarbons such as dichlorobenzene, toluene, xylene and mesitylene. , Aromatic hydrocarbons such as cyclohexylbenzene, aliphatic hydrocarbons such as cyclohexane, decalin and dodecane, and organic solvents such as DMF and DMSO can be used.

As the dispersion method, it is possible to disperse by a dispersion method such as ultrasonic wave, high shearing force dispersion or media dispersion.
Further, a different film forming method may be applied to each layer. When the vapor deposition method is adopted for film formation, the vapor deposition conditions vary depending on the type of compound used and the like, but generally, the boat heating temperature is in the range of 50 to 450° C., and the vacuum degree is in the range of 10 ⁻⁶ to 10 ⁻² Pa. Among them, the vapor deposition rate is 0.01 to 50 nm/sec, the substrate temperature is −50 to 300° C., the layer thickness is 0.1 nm to 5 μm, and preferably 5 to 200 nm. desirable.
When the spin coating method is used for film formation, it is preferable to perform the spin coater in a dry inert gas atmosphere within a range of 100 to 1000 rpm and within a range of 10 to 120 seconds.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, "%" is used, but "% by mass" is used unless otherwise specified.

The compounds used in Examples and Comparative Examples are shown below.

(Synthesis of Compound A-3)
International Publication No. 2010/113755, Organic Letters, 2002, 4, 1783-1785. , Angew. Chem. Int. Ed. 2010, 49, 2014-2017. Compound A-3 was synthesized using the method described in 1. Specifically, 1-bromo-3,4-difluorobenzene and carbazole were subjected to a nucleophilic substitution reaction to obtain a 1-bromo-3,4-dicarbazole intermediate.
The 1-bromo-3,4-dicarbazolylbenzene intermediate and 4-phenyl-1,2,3-triazole were reacted in the presence of a palladium catalyst to obtain a crude product of compound A-3. Then, column chromatography, recrystallization, and sublimation purification were performed to obtain a high-purity compound A-3.

(Synthesis of other compounds)
Compounds A-22, A-25, A-29, A-33, A-37, A-41, A-63 and A-64 were synthesized in the same manner as above.

The resulting compound and Delta] E _ST of comparative compounds 1 to 4, was calculated in the following manner.

(Calculation of ΔE _ST)
The structure optimization and the calculation of the electron density distribution by the molecular orbital calculation of the compound were calculated using the software for molecular orbital calculation using B3LYP as the functional and 6-31G(d) as the basis function as the calculation method. Gaussian09 (Revision C.01, MJ Frisch, et al, Gaussian, Inc., 2010.) manufactured by Gaussian, Inc., USA was used as the software for molecular orbital calculation.
From the structure optimization calculation using B3LYP as the functional and 6-31G(d) as the basis function, the excited state calculation by the time-dependent density functional method (Time-Dependent DFT) is further carried out to obtain S ₁ , T _1. the energy level (respectively _{E (S 1), E (} T 1)) of seeking _{ΔE ST = | E (S 1} ) -E (T 1) | is calculated as.

[Example 1]
(Production of Organic EL Element 1-1)
A transparent substrate with ITO (indium tin oxide) film formed as a positive electrode on a glass substrate of 50 mm x 50 mm and a thickness of 0.7 mm with a thickness of 150 nm, and then with this ITO transparent electrode attached. Was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.
Each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an optimum amount for producing each element. The vapor deposition crucible was made of a resistance heating material made of molybdenum or tungsten.

After the pressure was reduced to 1×10 ⁻⁴ Pa, the crucible for vapor deposition containing HAT-CN (1,4,5,8,9,12-hexaazatriphenylenehexacarbonitrile) was energized and heated to vaporize it. A hole injecting and transporting layer having a layer thickness of 10 nm was formed by vapor deposition on the ITO transparent electrode at a speed of 0.1 nm/sec.
Then, α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) was vapor-deposited on the hole injection layer at a vapor deposition rate of 0.1 nm/sec to give a layer thickness of 40 nm. To form a hole transport layer. The host compound H-232 and the comparative compound 1 were co-evaporated at a vapor deposition rate of 0.1 nm/sec so as to be 94% and 6% by volume, respectively, to form a light emitting layer having a layer thickness of 30 nm.
Then, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form an electron transport layer having a layer thickness of 30 nm.
Furthermore, after forming lithium fluoride with a film thickness of 0.5 nm, 100 nm of aluminum was vapor-deposited to form a cathode.
The non-light-emitting surface side of the above device was covered with a can glass case in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more, and electrode lead-out wiring was installed to produce an organic EL device 1-1.

(Production of Organic EL Elements 1-2 to 1-13)
Organic EL elements 1-2 to 1-13 were produced in the same manner as in the organic EL element 1-1 except that the light emitting compound was changed from comparative compound 1 as shown in Table 1.

[Example 2]
(Production of Organic EL Element 2-1)
After patterning a substrate (NA45 manufactured by NH Techno Glass Co., Ltd.) in which ITO (Indium Tin Oxide) was formed to a thickness of 100 nm on a glass substrate of 100 mm×100 mm×1.1 mm as an anode, this ITO transparent electrode was provided as a transparent support. The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone cleaned for 5 minutes.
On this transparent support substrate, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT/PSS, manufactured by Bayer, Baytron P Al 4083) was diluted to 70% with pure water to obtain 3000 rpm, After forming a thin film by spin coating under the condition of 30 seconds, it was dried at 200° C. for 1 hour to provide a hole injection layer having a layer thickness of 20 nm. This transparent support substrate was fixed to a substrate holder of a commercially available vacuum vapor deposition apparatus, and each of the vapor deposition crucibles in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an optimum amount for device production. The vapor deposition crucible was made of a resistance heating material made of molybdenum or tungsten.

After reducing the vacuum degree to 1×10 ⁻⁴ Pa, α-NPD was vapor-deposited on the hole injection layer at a vapor deposition rate of 0.1 nm/sec to form a hole transport layer having a layer thickness of 40 nm. H-234, 2,5,8,11-tetra-t-butylperylene was co-evaporated at a deposition rate of 0.1 nm/sec so that the volume% was 97% and 3%, respectively, and the light emission had a layer thickness of 30 nm. Layers were formed.
Then, TPBi (1,3,5-tris(N-phenylbenzimidazol-2-yl)) was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form an electron-transporting layer having a layer thickness of 30 nm.
Further, after forming sodium fluoride with a film thickness of 1 nm, 100 nm of aluminum was vapor-deposited to form a cathode.
The non-emission surface side of the above device was covered with a can glass case in an atmosphere of high purity nitrogen gas having a purity of 99.999% or more, and electrode lead-out wiring was installed to fabricate an organic EL device 2-1.

(Production of Organic EL Element 2-2)
H-234 was used as the host compound, 2,5,8,11-tetra-t-butylperylene was used as the luminescent compound, and Comparative Compound 1 was used as the third component, and the respective ratios were 82%, 3%, and 15% by volume. An organic EL element 2-2 was produced in the same manner as the organic EL element 2-1, except that the light emitting layer was formed so as to have a%.

(Production of Organic EL Elements 2-3 to 2-12)
As shown in Table 2, organic EL elements 2-3 to 2-12 were produced in the same manner as the organic EL element 2-2 except that the third component was changed.

[Example 3]
(Production of Organic EL Element 3-1)
A transparent substrate on which ITO (indium tin oxide) having a thickness of 150 nm was formed as an anode on a glass substrate having a size of 50 mm×50 mm and a thickness of 0.7 mm, followed by patterning, and then the ITO transparent electrode was attached. Was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

Each of the resistance heating boats for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an optimum amount for producing each element. The resistance heating boat was made of molybdenum or tungsten.

After decompressing to a vacuum degree of 1×10 ⁻⁴ Pa, a resistance heating boat containing HI-1 was energized and heated, and vapor-deposited on an ITO transparent electrode at a vapor deposition rate of 0.1 nm/sec. A hole injection layer was formed.

Then, α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) is deposited at a deposition rate of 0.1 nm/sec to form a hole transport layer having a layer thickness of 30 nm. did.

Then, a resistance heating boat containing Comparative Compound 1 and GD-1 as a comparative host compound is energized and heated to deposit on the hole transport layer at vapor deposition rates of 0.1 nm/sec and 0.010 nm/sec, respectively. Co-evaporation was performed to form a light emitting layer having a layer thickness of 40 nm.

Then, HB-1 was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a first electron-transporting layer having a layer thickness of 5 nm.

Further thereon, ET-1 was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a second electron transport layer having a layer thickness of 45 nm.

After that, lithium fluoride was vapor-deposited to a thickness of 0.5 nm, and then 100 nm of aluminum was vapor-deposited to form a cathode, to fabricate an organic EL element 3-1.

(Production of Organic EL Elements 3-2 to 3-11)
Organic EL elements 3-2 to 3-11 were produced in the same manner as in the organic EL element 3-1, except that the host compound was changed from comparative compound 1 as shown in Table 3.

(Measurement of luminous efficiency)
The luminous efficiency of each sample when the organic EL device was driven was evaluated by performing the following measurement.

(Measurement of relative luminous efficiency)
Each of the organic EL devices produced above was allowed to emit light at room temperature (about 25° C.) under a constant current condition of ^2.5 mA/cm ² , and the emission brightness immediately after the start of emission was measured by a spectral radiance meter CS-2000 (Konica Minolta). (Manufactured by the company).
Tables 1 to 3 show the obtained relative values of the emission brightness (relative value to the emission brightness of the organic EL element 1-1 in Example 1, and relative value to the emission brightness of the organic EL element 2-1 in Example 2. In Example 3, the relative value with respect to the emission brightness of the organic EL element 3-1 is shown.

From these results, the electron-withdrawing group A ¹ having the aromatic hetero 5-membered ring skeleton represented by the general formula (1), the para-position of the electron-withdrawing group A ¹ and adjacent to at least one of them It is clear that the π-conjugated compound of the present invention having an electron donating group has a higher relative luminous efficiency than the comparative compound. Further, the π-conjugated compound of the present invention (compound A-29) represented by the general formula (2) having an electron donating group on both sides of the para position of the electron-withdrawing group A ¹ has a general formula The relative luminous efficiency is higher than that of the π-conjugated compound represented by (1) (Compounds A-3, A-22, A-25), and Z ² and Z ^{3 on both} sides of the electron-withdrawing group A ¹ are hydrogen atoms. The relative emission efficiency of the π-conjugated compound represented by the general formula (3) (Compounds A-33, A-37, A-41) was further higher.

[Example 4]
(Production of Organic EL Element 4-1)
A transparent substrate on which ITO (indium tin oxide) having a thickness of 150 nm was formed as an anode on a glass substrate having a size of 50 mm×50 mm and a thickness of 0.7 mm, followed by patterning, and then the ITO transparent electrode was attached. Was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes, and then this transparent substrate was fixed to a substrate holder of a commercially available vacuum deposition apparatus.

Each of the resistance heating boats for vapor deposition in the vacuum vapor deposition apparatus was filled with the constituent material of each layer in an optimum amount for producing each element. The resistance heating boat was made of molybdenum or tungsten.

After decompressing to a vacuum degree of 1×10 ⁻⁴ Pa, electricity is applied to a resistance heating boat containing α-NPD (4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) to heat it. Then, vapor deposition was performed on the ITO transparent electrode at a vapor deposition rate of 0.1 nm/sec to form a hole injection layer having a layer thickness of 30 nm.

Then, TCTA (tris(4-carbazoyl-9-ylphenyl)amine) was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a first hole-transporting layer having a layer thickness of 20 nm.

Then, H-233 was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a second hole transport layer having a layer thickness of 10 nm.

Then, a resistance heating boat containing Comparative Compound 1 as a comparative host compound and TBPe (2,5,8,11-tetra-tert-butylperylene) was energized and heated, and the vapor deposition rate was 0.1 nm/sec. Was co-deposited on the hole transport layer at a rate of 0.010 nm/sec to form a light emitting layer having a layer thickness of 20 nm.

Next, H-232 was vapor-deposited at a vapor deposition rate of 0.1 nm/sec to form a first electron-transporting layer having a layer thickness of 10 nm.

Further thereon, TBPI (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene) was vapor-deposited at a vapor deposition rate of 0.1 nm/second to transport a second electron having a layer thickness of 30 m. Layers were formed.

After that, lithium fluoride was vapor-deposited to a thickness of 0.5 nm, and then 100 nm of aluminum was vapor-deposited to form a cathode, thereby producing an organic EL element 4-1.

(Production of Organic EL Elements 4-2 to 4-8)
Organic EL elements 4-2 to 4-8 were prepared in the same manner as the organic EL element 4-1, except that the host compound was changed from Comparative Compound 1 as shown in Table 4.

In all cases of the organic EL devices 4, the material of the present invention showed higher luminous efficiency than the comparative compound.

[Example 5]
The luminance half-time when the organic EL element 1-9 of Example 1 was turned on at an initial luminance of 300 cd/m ² was measured.

(Production of Organic EL Elements 5-1 to 5-9)
Organic EL elements 5-1 to 5-9 were prepared from the element 1-13 of Example 1 by the same method as the organic EL element 1-13 except that the host compound and the light emitting compound were changed as shown in Table 5. did.

In the organic EL device 5, when the host compound was the compound represented by the general formula (I), the relative luminance half-life was particularly long. In addition, when the light emitting compound was the compound represented by the general formula (3) (Compound A-41), it had a long relative luminance half time.

According to the present invention, it is possible to provide a new π-conjugated compound capable of improving the luminous efficiency of an organic electroluminescence device, for example. Further, it is possible to provide an organic electroluminescence element material, a light emitting thin film, a light emitting material, an organic electroluminescence element using the π-conjugated compound, and a display device and a lighting device provided with the organic electroluminescence element.

1 Display 3 Pixel 5 Scan Line 6 Data Line 7 Power Line 10 Organic EL Element 11 Switching Transistor 12 Driving Transistor 13 Capacitor 101 Organic EL Element in Lighting Device 102 Glass Cover 105 Cathode 106 Organic Layer 107 Glass Substrate with Transparent Electrode 108 Nitrogen Gas 109 Water trap A Display B Control C Wiring

Claims (20)

A π-conjugated compound having a structure represented by the following general formula (1).

(In the general formula (1),
A ¹ represents an optionally substituted furan ring, triazole ring, or benzotriazole ring,
D ¹ and D ² each independently represent an electron-donating group,
Z ¹ represents an electron donating group ,
Z ² and Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group,
The electron-donating group represented by D ¹ and D ² and Z ¹ is an alkyl group, an alkoxy group, an optionally substituted amino group, or an optionally substituted pyrrole ring, indole ring, carbazole ring. , Indoloindole ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, Benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, azacarbazole ring, aryl group substituted with diazacarbazole ring, optionally substituted pyrrole ring, indole ring, carbazole ring, indoloindole ring, 9 , 10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene ring, benzo A group selected from the group consisting of a carbazole ring, a dibenzocarbazole ring, an azacarbazole ring, a diazacarbazole ring, an optionally substituted amino group, and an alkyl group,
The electron-withdrawing group represented by Z ² and Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an unsubstituted group. Optionally phosphine oxide group, optionally substituted boryl group, fluorine atom, cyano group, optionally fluorine substituted alkyl group, optionally substituted carbonyl group, optionally substituted sulfonyl group , Optionally substituted phosphine oxide group, optionally substituted boryl group, and optionally substituted imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole Ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide Ring, benzimidazole ring, indazole ring, benzotriazole ring, benzofuran ring, benzoxazole ring, benzooxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophenediene ring Oxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, Azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, feh An aryl group which may be substituted with a nantrizine ring, and an imidazole ring which may be substituted, a pyrazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a furan ring, Oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide ring, benzimidazole ring, indazole ring , Benzotriazole ring, benzofuran ring, benzoxazole ring, benzoo Oxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophene dioxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, Azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine A ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, and a phenanthridine ring. ) Formula Te (1) odor, Z ² and Z ³ represents a hydrogen atom, [pi conjugated compound according to claim 1. The π-conjugated compound according to claim 1 , wherein A ¹ contains a nitrogen atom. Absolute value Delta] E _ST of the energy difference between the lowest excited singlet state and the lowest excited triplet level is below 0.50eV, π-conjugated compound according to any one of claims 1 to 3. An organic electroluminescence device material containing a π-conjugated compound having a structure represented by the following general formula (1) .

(In the general formula (1),
A ¹ represents an optionally substituted furan ring, triazole ring, or benzotriazole ring,
D ¹ and D ² each independently represent an electron-donating group,
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group,
The electron-donating group represented by D ¹ and D ² and Z ^{1 to} Z ³ is an alkyl group, an alkoxy group, an optionally substituted amino group, or an optionally substituted pyrrole ring or indole ring. , Carbazole ring, indoloindole ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothieno ring Carbazole ring, benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, azacarbazole ring, aryl group substituted with diazacarbazole ring, optionally substituted pyrrole ring, indole ring, carbazole ring, indoloindole Ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene A ring, a benzocarbazole ring, a dibenzocarbazole ring, an azacarbazole ring, a diazacarbazole ring, an optionally substituted amino group, and a group selected from the group consisting of an alkyl group,
The electron withdrawing group represented by Z ^{1 to} Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an unsubstituted group. Optionally phosphine oxide group, optionally substituted boryl group, fluorine atom, cyano group, optionally fluorine substituted alkyl group, optionally substituted carbonyl group, optionally substituted sulfonyl group , Optionally substituted phosphine oxide group, optionally substituted boryl group, and optionally substituted imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole Ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide Ring, benzimidazole ring, indazole ring, benzotriazole ring, benzofuran ring, benzoxazole ring, benzooxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophenediene ring Oxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, Azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, feh An aryl group which may be substituted with a nantrizine ring, and an imidazole ring which may be substituted, a pyrazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a furan ring, Oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide ring, benzimidazole ring, indazole ring , Benzotriazole ring, benzofuran ring, benzoxazole ring, benzoo Oxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophene dioxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, Azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine A ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, and a phenanthridine ring. ) A luminescent material comprising a π-conjugated compound having a structure represented by the following general formula (1) , wherein the π-conjugated compound emits fluorescence.

(In the general formula (1),
A ¹ represents an optionally substituted furan ring, triazole ring, or benzotriazole ring,
D ¹ and D ² each independently represent an electron-donating group,
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group,
The electron-donating group represented by D ¹ and D ² and Z ^{1 to} Z ³ is an alkyl group, an alkoxy group, an optionally substituted amino group, or an optionally substituted pyrrole ring or indole ring. , Carbazole ring, indoloindole ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothieno ring Carbazole ring, benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, azacarbazole ring, aryl group substituted with diazacarbazole ring, optionally substituted pyrrole ring, indole ring, carbazole ring, indoloindole Ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene A ring, a benzocarbazole ring, a dibenzocarbazole ring, an azacarbazole ring, a diazacarbazole ring, an optionally substituted amino group, and a group selected from the group consisting of an alkyl group,
The electron withdrawing group represented by Z ^{1 to} Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an unsubstituted group. Optionally phosphine oxide group, optionally substituted boryl group, fluorine atom, cyano group, optionally fluorine substituted alkyl group, optionally substituted carbonyl group, optionally substituted sulfonyl group , Optionally substituted phosphine oxide group, optionally substituted boryl group, and optionally substituted imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole Ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide Ring, benzimidazole ring, indazole ring, benzotriazole ring, benzofuran ring, benzoxazole ring, benzooxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophenediene ring Oxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, Azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, feh An aryl group which may be substituted with a nantrizine ring, and an imidazole ring which may be substituted, a pyrazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a furan ring, Oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide ring, benzimidazole ring, indazole ring , Benzotriazole ring, benzofuran ring, benzoxazole ring, benzoo Oxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophene dioxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, Azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine It is a group selected from the group consisting of a ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, and a phenanthridine ring. ) The light emitting material according to claim 6 , wherein the π-conjugated compound emits delayed fluorescence. A luminescent thin film containing a π-conjugated compound having a structure represented by the following general formula (1) .

(In the general formula (1),
A ¹ represents an optionally substituted furan ring, triazole ring, or benzotriazole ring,
D ¹ and D ² each independently represent an electron-donating group,
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group,
The electron-donating group represented by D ¹ and D ² and Z ^{1 to} Z ³ is an alkyl group, an alkoxy group, an optionally substituted amino group, or an optionally substituted pyrrole ring or indole ring. , Carbazole ring, indoloindole ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothieno ring Carbazole ring, benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, azacarbazole ring, aryl group substituted with diazacarbazole ring, optionally substituted pyrrole ring, indole ring, carbazole ring, indoloindole Ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene A ring, a benzocarbazole ring, a dibenzocarbazole ring, an azacarbazole ring, a diazacarbazole ring, an optionally substituted amino group, and a group selected from the group consisting of an alkyl group,
The electron withdrawing group represented by Z ^{1 to} Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an unsubstituted group. Optionally phosphine oxide group, optionally substituted boryl group, fluorine atom, cyano group, optionally fluorine substituted alkyl group, optionally substituted carbonyl group, optionally substituted sulfonyl group , Optionally substituted phosphine oxide group, optionally substituted boryl group, and optionally substituted imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole Ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide Ring, benzimidazole ring, indazole ring, benzotriazole ring, benzofuran ring, benzoxazole ring, benzooxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophenediene ring Oxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, Azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, feh An aryl group which may be substituted with a nantrizine ring, and an imidazole ring which may be substituted, a pyrazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a furan ring, Oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide ring, benzimidazole ring, indazole ring , Benzotriazole ring, benzofuran ring, benzoxazole ring, benzoo Oxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophene dioxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, Azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine A ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, and a phenanthridine ring. ) The luminescent thin film according to claim 8 , wherein the π-conjugated compound emits delayed fluorescence. An anode, a cathode, and a light emitting layer provided between the anode and the cathode,
An organic electroluminescent device, wherein at least one of the light emitting layers contains a π-conjugated compound having a structure represented by the following general formula (1) .

(In the general formula (1),
A ¹ represents an optionally substituted furan ring, triazole ring, or benzotriazole ring,
D ¹ and D ² each independently represent an electron-donating group,
Z ^{1 to} Z ³ each independently represent a hydrogen atom, a deuterium atom, an electron-donating group or an electron-withdrawing group,
The electron-donating group represented by D ¹ and D ² and Z ^{1 to} Z ³ is an alkyl group, an alkoxy group, an optionally substituted amino group, or an optionally substituted pyrrole ring or indole ring. , Carbazole ring, indoloindole ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothieno ring Carbazole ring, benzothienobenzothiophene ring, benzocarbazole ring, dibenzocarbazole ring, azacarbazole ring, aryl group substituted with diazacarbazole ring, optionally substituted pyrrole ring, indole ring, carbazole ring, indoloindole Ring, 9,10-dihydroacridine ring, phenoxazine ring, phenothiazine ring, dibenzothiophene ring, benzofurylindole ring, benzothienoindole ring, indolocarbazole ring, benzofurylcarbazole ring, benzothienocarbazole ring, benzothienobenzothiophene A ring, a benzocarbazole ring, a dibenzocarbazole ring, an azacarbazole ring, a diazacarbazole ring, an optionally substituted amino group, and a group selected from the group consisting of an alkyl group,
The electron withdrawing group represented by Z ^{1 to} Z ³ is a fluorine atom, an alkyl group substituted with a fluorine atom, an optionally substituted carbonyl group, an optionally substituted sulfonyl group, or an unsubstituted group. Optionally phosphine oxide group, optionally substituted boryl group, fluorine atom, cyano group, optionally fluorine substituted alkyl group, optionally substituted carbonyl group, optionally substituted sulfonyl group , Optionally substituted phosphine oxide group, optionally substituted boryl group, and optionally substituted imidazole ring, pyrazole ring, 1,2,3-triazole ring, 1,2,4-triazole Ring, tetrazole ring, furan ring, oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide Ring, benzimidazole ring, indazole ring, benzotriazole ring, benzofuran ring, benzoxazole ring, benzooxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophenediene ring Oxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, Azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, quinoline ring, isoquinoline ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, feh An aryl group optionally substituted with a nantrizine ring, and an optionally substituted imidazole ring, a pyrazole ring, a 1,2,3-triazole ring, a 1,2,4-triazole ring, a tetrazole ring, a furan ring, Oxazole ring, isoxazole ring, oxadiazole ring, thiophene ring, thiophene dioxide ring, thiazole ring, isothiazole ring, thiadiazole ring, silole ring, borole ring, phosphole ring, phosphole oxide ring, benzimidazole ring, indazole ring , Benzotriazole ring, benzofuran ring, benzoxazole ring, benzoo Oxadiazole ring, benzothiophene ring, benzothiophene dioxide ring, benzothiazole ring, benzothiadiazole ring, dibenzofuran ring, dibenzothiophene dioxide ring, dibenzosilole ring, dibenzoborol ring, dibenzophosphole ring, dibenzophosphole oxide ring, Azadibenzofuran ring, azadibenzothiophene ring, azadibenzothiophene dioxide ring, azadibenzosilole ring, azadibenzoborol ring, azadibenzophosphole ring, azadibenzophosphole oxide ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine A ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinazoline ring, a cinnoline ring, a quinoxaline ring, a phthalazine ring, a pteridine ring, and a phenanthridine ring. ) The organic electroluminescent device according to claim 10 , wherein the π-conjugated compound produces excitons. The organic electroluminescence device according to claim 10 , wherein the π-conjugated compound emits fluorescence. The organic electroluminescent device according to claim 12 , wherein the π-conjugated compound emits delayed fluorescence. The organic electroluminescent element according to claim 10 , wherein the light emitting layer contains the π-conjugated compound and a host compound. The organic electroluminescence device according to claim 10 , wherein the light emitting layer contains the π-conjugated compound and at least one of a fluorescent light emitting compound and a phosphorescent light emitting compound. The organic electroluminescent element according to claim 10 , wherein the light emitting layer contains the π-conjugated compound, at least one of a fluorescent light emitting compound and a phosphorescent light emitting compound, and a host compound. .. The organic electroluminescence device according to claim 14 or 16 , wherein the host compound has a structure represented by the following general formula (I).

(In the general formula (I),
X ₁₀₁ represents NR ₁₀₁ , an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₄ R ₁₀₅ ,
y _{1 to} y ₈ each independently represent CR ₁₀₆ or a nitrogen atom,
R _{101 to} R ₁₀₆ each independently represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring,
Ar ₁₀₁ and Ar ₁₀₂ each independently represent an optionally substituted aryl group or an optionally substituted heteroaryl group,
n101 and n102 each represent an integer of 0 to 4.
However, when R ₁₀₁ is a hydrogen atom, n ₁₀₁ represents an integer of 1 to 4. ) The organic electroluminescence device according to claim 17 , wherein the host compound having a structure represented by the general formula (I) has a structure represented by the following general formula (II).

(In the general formula (II),
X ₁₀₁ represents NR ₁₀₁ , an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, CR ₁₀₂ R ₁₀₃ or SiR ₁₀₄ R ₁₀₅ ,
R _{101 to} R ₁₀₅ each represent a hydrogen atom or a substituent, and may be bonded to each other to form a ring,
Ar ₁₀₁ and Ar ₁₀₂ each independently represent an optionally substituted aryl group or an optionally substituted heteroaryl group,
n102 represents an integer of 0 to 4. ) A display device comprising the organic electroluminescence element according to claim 10 . A lighting device comprising the organic electroluminescent element according to claim 10 .

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