WO2023090404A1

WO2023090404A1 - Condensed ring fluorene compound, material for organic electroluminescent element, and organic electroluminescent element

Info

Publication number: WO2023090404A1
Application number: PCT/JP2022/042770
Authority: WO
Inventors: 内田直樹; 上原史成; 尾池華奈; 高橋泰裕; 野村真太朗
Original assignee: 東ソー株式会社
Priority date: 2021-11-18
Filing date: 2022-11-17
Publication date: 2023-05-25
Also published as: JP2023075069A

Abstract

Provided are: a novel condensed ring fluorene compound that facilitates the production of an organic electroluminescent element in which driving the voltage can be reduced; a material for an organic electroluminescent element, the material containing said condensed ring fluorene compound; and an organic electroluminescent element.　The present invention provides: a condensed ring fluorene compound having a specific structure represented by formula (1); a material for an organic electroluminescent element, the material containing said condensed ring fluorene compound; and an organic electroluminescent element.

Description

Fused ring fluorene compound, material for organic electroluminescence device, and organic electroluminescence device

The present invention relates to a condensed ring fluorene compound, a material for an organic electroluminescence device containing the condensed ring fluorene compound, and an organic electroluminescence device.

Practical use of organic electroluminescent elements has begun, mainly for small mobile applications. However, performance improvement is essential for further expansion of applications, and materials with high current efficiency, low driving voltage, high luminous efficiency characteristics, and long life characteristics are required. Patent Documents 1 and 2 disclose fluorene compounds, which are materials for organic electroluminescent devices.

Japanese Patent Application Publication No. 2011-530802 International Publication 2017/047993 Pamphlet

However, it cannot be said that the fluorene compounds according to Patent Documents 1 and 2 sufficiently satisfy the driving voltage characteristics.

Therefore, one aspect of the present invention is directed to providing a new condensed ring fluorene compound that contributes to the formation of an organic electroluminescent device capable of reducing the driving voltage.

Furthermore, still another aspect of the present invention is directed to providing an organic electroluminescence device with reduced driving voltage.

That is, the present invention resides in the following [1] to [5].
[1] A condensed fluorene compound represented by formula (1).

In formula (1),
Ring A represents a fluoranthene ring represented by formula (A-1) or an optionally substituted benzofluoranthene ring;

R ¹ , R ² and R′ are each independently
an optionally substituted alkyl group having 1 to 10 carbon atoms, or
(i) an aromatic hydrocarbon group having 6 to 60 carbon atoms, which may be optionally substituted, which is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked;
(ii) a heteroaromatic group having 3 to 60 carbon atoms, or
(iii) an arylamino group having 6 to 60 carbon atoms, or (iv) a group composed of a combination of any two or more selected from the above (i) to (iii);
*1 represents a condensation site;
n is an integer from 0 to 6;
When R ¹ and R ² are an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 60 carbon atoms, R ¹ and R ² may be linked together to form a ring;
However, when ring A is formula (A-1), R ¹ and R ² are not methyl groups.

Ring B is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked, which may be optionally substituted (i) an aromatic hydrocarbon having 6 to 20 carbon atoms base, or
(ii) represents a heteroaromatic group having 3 to 20 carbon atoms;
[2] The fused ring fluorene compound according to [1], wherein ring A is formula (A-1) or (A-2).

During the ceremony,
R' and n are as defined in [1];
m is an integer from 0 to 4;
In formula (A-2), any two adjacent hydrogens are condensation sites.
[3] The fused ring fluorene compound according to [1], wherein ring A is formula (A-2).
[4] The condensed ring fluorene compound according to [1], wherein the compound represented by formula (1) is represented below.

[5] an anode;
a cathode;
and one or more organic thin film layers including at least a light-emitting layer,
An organic electroluminescence device, wherein at least one of the organic thin film layers contains the condensed ring fluorene compound according to any one of [1] to [4].

According to one aspect of the present invention, it is possible to provide a new condensed ring fluorene compound that contributes to the formation of an organic electroluminescent device capable of reducing driving voltage.

Further, according to another aspect of the present invention, it is possible to provide a material for an organic electroluminescence device and an electron transport material for an organic electroluminescence device containing the fused ring fluorene compound. Furthermore, according to still another aspect of the present invention, it is possible to provide an organic electroluminescence device with reduced driving voltage.

1 is a schematic cross-sectional view showing an example of a layered structure of an organic electroluminescence element according to one aspect of the present disclosure; FIG. FIG. 4 is a schematic cross-sectional view showing another example of the layered structure of the organic electroluminescence element according to one aspect of the present disclosure (structure of Element Example-1).

Each aspect of the present invention will be described in detail below.

A fused ring fluorene compound according to one aspect of the present invention is a fused ring fluorene compound represented by formula (1).

R ¹ , R ² and R′ are each independently
an optionally substituted alkyl group having 1 to 10 carbon atoms, or
(i) an aromatic hydrocarbon group having 6 to 60 carbon atoms, which may be optionally substituted, which is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked;
(ii) a heteroaromatic group having 3 to 60 carbon atoms;
(iii) an arylamino group having 6 to 60 carbon atoms, or
(iv) represents a group composed of any combination of two or more selected from the above (i) to (iii);
*1 represents a condensation site;
n is an integer from 0 to 6;
When R ¹ and R ² are an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 60 carbon atoms, R ¹ and R ² may be linked together to form a ring;
However, when ring A is formula (A-1), R ¹ and R ² are not methyl groups.

Ring B is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked, which may be optionally substituted (i) an aromatic hydrocarbon having 6 to 20 carbon atoms base, or
(ii) represents a heteroaromatic group having 3 to 20 carbon atoms;
[About ring A]
Ring A represents a fluoranthene ring represented by formula (A-1) or an optionally substituted benzofluoranthene ring.

A benzofluoranthene ring, which is one embodiment of ring A, is preferably represented by formula (A-2).

In formula (A-2), any two adjacent hydrogens are condensation sites.

More preferably, ring A is represented by formula (A-2).
[Regarding R ¹ , R ² and R′]
R ¹ , R ² and R′ are each independently
an optionally substituted alkyl group having 1 to 10 carbon atoms, or
(i) an aromatic hydrocarbon group having 6 to 60 carbon atoms, which may be optionally substituted, which is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked;
(ii) a heteroaromatic group having 3 to 60 carbon atoms, or
(iii) an arylamino group having 6 to 60 carbon atoms, or (iv) a group composed of any combination of two or more selected from (i) to (iii) above.

However, when the aforementioned ring A has the formula (A-1), R ¹ and R ² are not methyl groups.

Specific examples of alkyl groups having 1 to 10 carbon atoms are
a methyl group, an ethyl group, or optionally branched or cyclized,
propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, adamantyl group and the like.

Specific examples of the aryl group having 6 to 60 carbon atoms include a phenyl group, naphthyl group, phenanthryl group, anthonyl group, pyrenyl group, perylenyl group, fluorenyl group, dimethylfluorenyl group, diphenylfluorenyl group, triphenylenyl group, fluoranthenyl group, benzofluoranthenyl group, chrysenyl group, dibenzochrysenyl group, dinaphthochrysenyl group and the like.

Specific examples of heteroaryl groups having 3 to 60 carbon atoms include pyridyl group, pyrimidyl group, pyrazyl group, triazinyl group, quinolyl group, isoquinolyl group, nadityridinyl group, acridinyl group, phenanthrolinyl group and phenanthridinyl group. , pyrrolyl group, indolyl group, indolidinyl group, carbazolyl group, carbolinyl group, benzocarbazolyl group, benzocarbolinyl group, furanyl group, benzofuranyl group, dibenzofuranyl group, xanthenyl group, spiroxanthenyl group, benzoxanthenyl group group, thienyl group, benzothienyl group, dibenzothienyl group, oxazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group and the like.

Specific examples of the arylamino group having 6 to 60 carbon atoms include phenylamino group, diphenylamino group, biphenylylamino group, dibiphenylylamino group, naphthylamino group, dinaphthylamino group and the like.

When R ¹ and R ² are an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 60 carbon atoms, R ¹ and R ² may be linked together to form a ring.

R ¹ and R ² are preferably a phenyl group, a fluoranthenyl group, a benzofluoranthenyl group and a triazinylphenyl group.
[About ring B]
Ring B is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked, which may be optionally substituted (i) an aromatic hydrocarbon having 6 to 20 carbon atoms base, or
(ii) represents a heteroaromatic group having 3 to 20 carbon atoms;

Specific examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include phenyl, naphthyl, phenanthryl, anthnyl, pyrenyl, perylenyl, fluorenyl, dimethylfluorenyl, diphenylfluorenyl, triphenylenyl group, fluoranthenyl group and the like.

Specific examples of heteroaromatic groups having 3 to 20 carbon atoms include pyridyl, pyrimidyl, pyrazyl, triazinyl, quinolyl, isoquinolyl, nadityridinyl, acridinyl, phenanthrolinyl, and phenanthridinyl. pyrrolyl group, indolyl group, indolizinyl group, carbazolyl group, carbolinyl group, benzocarbazolyl group, benzocarbolinyl group, furanyl group, benzofuranyl group, dibenzofuranyl group, xanthenyl group, spiroxanthenyl group, benzoxane a thenyl group, a thienyl group, a benzothienyl group, a dibenzothienyl group, an oxazolyl group, a benzoxazolyl group, a thiazolyl group, a benzothiazolyl group and the like.

Ring B is preferably a phenyl group, a naphthyl group, a pyridyl group, a quinolyl group, or an isoquinolyl group.
[About substituents]
Each group represented by ring A, ring B, R ¹ , R ² and R′ is deuterium, fluorine atom, chlorine atom, bromine atom, iodine atom, formyl group, cyano group, nitro group, branched or cyclized an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms which may be branched or cyclic, an alkynyl group which may be branched or cyclic, an alkoxy group having 1 to 20 carbon atoms, a monocyclic or optionally linked aromatic hydrocarbon group having 6 to 20 carbon atoms, monocyclic or optionally linked heteroaromatic group having 3 to 20 carbon atoms, P(=O)(R'') ₂ , C( =O) substituted with one or more substituents selected from the group consisting of R'', B(R'') ₂ , B(OR'') ₂ , _OSO2R '', Si(R'') ₄ may be

R'' is the same or different in each occurrence and is composed of the group consisting of an alkyl group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 60 carbon atoms, and a heteroaromatic group having 3 to 60 carbon atoms. be done.

Specific examples of the condensed fluorene compound are shown below. In addition, this invention is not limited to these.

The condensed fluorene compound can be used, for example, for organic electronic devices such as organic electroluminescence devices and photoelectric devices.
<Materials for Organic Electroluminescent Devices>
A material for an organic electroluminescence device according to one aspect of the present invention contains a condensed ring fluorene compound.

A condensed fluorene compound can be used, for example, as an electron transport material for an organic electroluminescence device.

The structural reasons why the condensed ring fluorene compound according to one aspect of the present invention exhibits a low driving voltage as, for example, an electron-transporting material for an organic electroluminescence device are presumed to be as follows.
<Structural reasons for low drive voltage>
In 9H-fluorene, two substituents can be introduced at the 9-position of the structure so as to be perpendicular to the plane of the fluorene ring. A 9,9-disubstituted fluorene ring in which a substituent is introduced at the 9-position inhibits its own π-stack and suppresses intermolecular interaction, thereby making it possible to improve the efficiency of organic electroluminescence devices.

However, the charge transport property of the 9,9-disubstituted fluorene skeleton itself, which suppresses the π-π stack between molecules, is poor. A measure is taken to complement the charge transport property by introducing it.

On the other hand, fluorene compounds having a fluoranthene skeleton formed by the condensation of a naphthalene ring and a fluorene ring have been reported. It is a thing. These structures have inappropriate energy levels (HOMO or LUMO levels) involved in charge transport, and are disadvantageous for charge transport from or to adjacent layers.

In contrast, the condensed fluorene compound, which is one embodiment of the present application, has a structure condensed with fluoranthene at positions 7 and 8 or with benzofluoranthene. As a result, it is possible to promote π-stacking of the fluoranthene ring responsible for charge transport and to have an appropriate energy level while maintaining the effect of improving efficiency by suppressing the interaction due to the 9,9-disubstituted structure of fluorene.
<Organic electroluminescent device>
An organic electroluminescence device (hereinafter sometimes simply referred to as an organic electroluminescence device) according to one aspect of the present invention will be described below.

An organic electroluminescent device according to one aspect of the present invention contains a condensed ring fluorene compound.

The configuration of the organic electroluminescent element is not particularly limited, but includes, for example, the configurations (i) to (vii) shown below.

(i): anode/light emitting layer/cathode (ii): anode/hole transport layer/light emitting layer/cathode (iii): anode/light emitting layer/electron transport layer/cathode (iv): anode/hole transport layer/ Emissive layer/electron transport layer/cathode (v): anode/hole injection layer/hole transport layer/emissive layer/electron transport layer/electron injection layer/cathode (vi): anode/hole injection layer/hole transport Layer/electron-blocking layer/light-emitting layer/hole-blocking layer/electron-transporting layer/electron-injecting layer/cathode (vii): anode/hole-injecting layer/first hole-transporting layer/second hole-transporting layer/light-emitting layer /First electron-transporting layer/Second electron-transporting layer/Cathode The condensed ring fluorene compound may be contained in any of the above layers. It is preferably contained in one or more layers selected from the group consisting of layers between the layer and the cathode. Therefore, in the structures shown in (i) to (vii) above, the pyrimidine compound is preferably contained in one or more layers selected from the group consisting of a light-emitting layer, an electron-transporting layer, and an electron-injecting layer.

Hereinafter, the organic electroluminescence device according to one aspect of the present invention will be described in more detail with reference to FIG. 1, taking the configuration (v) above as an example.

The organic electroluminescent device shown in FIG. 1 has a so-called bottom emission type device configuration, but the organic electroluminescent device according to one aspect of the present invention is not limited to the bottom emission type device configuration. do not have. That is, the organic electroluminescence device according to one aspect of the present invention may have other known device configurations such as top emission type.

FIG. 1 is a schematic cross-sectional view showing an example of a laminated structure of an organic electroluminescence device according to one aspect of the present invention.

The organic electroluminescent device 100 includes a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, and a cathode 8 in this order. However, some of these layers may be omitted, or conversely, other layers may be added. For example, a hole-blocking layer may be provided between the light-emitting layer 5 and the electron-transporting layer 6, the hole-injecting layer 3 may be omitted, and the hole-transporting layer 4 may be provided directly on the anode 2. good too.

Further, a single layer having the functions of a plurality of layers, such as an electron injection/transport layer having both the function of an electron injection layer and the function of an electron transport layer in a single layer. It may be a configuration provided instead of. Furthermore, for example, the single-layer hole transport layer 4 and the single-layer electron transport layer 6 may each consist of a plurality of layers.
<Layer containing condensed fluorene compound>
In the structural example shown in FIG. 1, the organic electroluminescent device 100 contains the condensed ring fluorene compound in one or more layers selected from the group consisting of the light-emitting layer 5, the electron transport layer 6 and the electron injection layer . In particular, the electron transport layer 6 preferably contains a condensed fluorene compound. Note that the condensed fluorene compound may be contained in a plurality of layers included in the organic electroluminescence device.

An organic electroluminescence device 100 in which the electron transport layer 6 contains a condensed fluorene compound will be described below.
[Substrate 1]
The substrate 1 is not particularly limited, and substrates that can be used in ordinary organic electroluminescence devices can be used. For example, a glass plate, a quartz plate, a plastic plate and the like can be used.
[Anode 2]
An anode 2 is provided on the substrate 1 (on the hole injection layer 3 side).

As the material for the anode, compounds that can be used in ordinary organic electroluminescence devices can be used. Examples include metals, alloys, electrically conductive compounds, and mixtures thereof with a large work function (eg, 4 eV or more). Specific examples of materials for the anode include metals such as Au; conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ and ZnO.
[Hole injection layer 3, hole transport layer 4]
A hole injection layer 3 and a hole transport layer 4 are provided in this order from the anode 2 side between the anode 2 and a light emitting layer 5 to be described later.

The material for the hole injection layer and the hole transport layer has at least one of hole injection, hole transport, and electron barrier properties. Materials for the hole injection layer and the hole transport layer may be either organic or inorganic, and compounds that can be used in ordinary organic electroluminescence devices can be used.

The hole injection layer and hole transport layer may have a single structure composed of one or more materials, or may have a laminated structure composed of multiple layers of the same composition or different compositions.

The hole-transporting layer 4 may have a laminated structure of two or more layers, and is provided in this order from the anode 2 side with a first hole-transporting layer 41 and a second hole-transporting layer 42 . The transport layer 42 can be used as an electron blocking layer in the configuration (vi) above.
[Light emitting layer 5]
A light-emitting layer 5 is provided between the hole-transporting layer 4 and an electron-transporting layer 6, which will be described later.

As the material for the light-emitting layer, light-emitting materials that can be used in ordinary organic electroluminescent devices can be used. Examples thereof include phosphorescent materials, fluorescent materials, and heat-activated delayed fluorescent materials.

The light emitting layer may consist of a single small molecule material or a single polymer material, but more commonly consists of a host material doped with a guest compound. Emission comes primarily from dopants and can have any color.

Also, the luminescent material is not limited to being contained only in the luminescent layer. For example, the light-emitting material may be contained in a layer adjacent to the light-emitting layer (hole-transporting layer 4 or electron-transporting layer 6). This can further increase the luminous efficiency of the organic electroluminescence device.

The light-emitting layer may have a single-layer structure composed of one or more materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.
[Electron transport layer 6]
An electron transport layer 6 is provided between the light emitting layer 5 and an electron injection layer 7 which will be described later.

The electron transport layer preferably contains a condensed fluorene compound. In addition to the pyrimidine compound, the electron transport layer may further contain one or more selected from conventionally known electron transport materials.

When the condensed fluorene compound is not contained in the electron-transporting layer but is contained in another layer, one or more selected from conventionally known electron-transporting materials can be used as the electron-transporting material constituting the electron-transporting layer. can.

Conventionally known electron-transporting materials include alkali metal complexes, alkaline earth metal complexes, earth metal complexes, and the like. Alkali metal complexes, alkaline earth metal complexes, and earth metal complexes include, for example, 8-hydroxyquinolinatolithium (Liq), bis(8-hydroxyquinolinato)zinc, and bis(8-hydroxyquinolinato)copper. , bis(8-hydroxyquinolinato)manganese, tris(8-hydroxyquinolinato)aluminum, tris(2-methyl-8-hydroxyquinolinato)aluminum, tris(8-hydroxyquinolinato)gallium, bis (10-hydroxybenzo[h]quinolinate) beryllium, bis(10-hydroxybenzo[h]quinolinate)zinc, bis(2-methyl-8-quinolinato)chlorogallium, bis(2-methyl-8-quinolinate)(o -cresolato)gallium, bis(2-methyl-8-quinolinato)-1-naphtholatoaluminum, bis(2-methyl-8-quinolinato)-2-naphtholatogallium, and the like.

The electron-transporting layer may have a single-layer structure composed of one or more materials, or may have a laminated structure composed of multiple layers having the same composition or different compositions.

An electron injection layer may be provided in the organic electroluminescence device according to this aspect for the purpose of improving electron injection properties and improving device characteristics (e.g., luminous efficiency, low voltage drive, or high durability).

The electron transport layer 6 may have a laminated structure of two or more layers, and is provided in the order of a first electron transport layer 61 and a second electron transport layer 62 from the light emitting layer 5 side. can be used as the hole blocking layer in the configuration (vi) above.

The fused ring fluorene compound according to one aspect of the present invention can be used in both or either one of the first electron-transporting layer and the second electron-transporting layer.
[Electron injection layer 7]
An electron injection layer 7 is provided between the electron transport layer 6 and a cathode 8 which will be described later.

As the material for the electron injection layer, compounds that can be used in ordinary organic electroluminescent devices can be used. Examples thereof include organic compounds such as fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenylidenemethane, anthraquinodimethane, and anthrone.

Materials for the electron injection layer include various oxides and fluorides such as SiO ₂ , AlO, SiN, SiON, AlON, GeO, LiO, LiON, TiO, TiON, TaO, TaON, TaN, LiF, C, and Yb. , nitrides, and oxynitrides. Fused ring fluorene compounds of the present invention can also be used.
[Cathode 8]
A cathode 8 is provided on the electron injection layer 7 .

As the cathode material, compounds that can be used in ordinary organic electroluminescent devices can be used. Examples include metals with a small work function (hereinafter also referred to as electron-injecting metals), alloys, electrically conductive compounds, and mixtures thereof. Here, a metal with a small work function is, for example, a metal of 4 eV or less.

A mixture of an electron-injecting metal and a second metal that has a higher work function and is more stable, such as magnesium/silver mixture, magnesium/aluminum mixture, magnesium/indium mixture, aluminum/aluminum oxide (Al ₂ O ₃ ) mixtures, lithium/aluminum mixtures, etc. are preferred.
[Method of Forming Each Layer]
Each layer except for the electrodes (anode, cathode) described above is formed by thinning by a known method such as a vacuum deposition method, a spin coating method, a casting method, or a LB (Langmuir-Blodgett method) method. be able to. The material for each layer may be used alone, or if necessary, it may be used together with a material such as a binder resin and a solvent.

The film thickness of each layer thus formed is not particularly limited and can be appropriately selected depending on the situation, but is usually in the range of 5 nm to 5 μm.

The anode and cathode can be formed by thinning the electrode material by a method such as vapor deposition or sputtering. A pattern may be formed through a mask of a desired shape during vapor deposition or sputtering, or a pattern of a desired shape may be formed by photolithography after forming a thin film by vapor deposition, sputtering, or the like.

The film thickness of the anode and cathode is preferably 1 μm or less, more preferably 10 nm or more and 200 nm or less.

It should be noted that the layer containing the condensed ring fluorene compound may be formed in combination with the conventionally known electron-transporting material. Therefore, for example, a condensed ring fluorene compound and a conventionally known electron-transporting material may be co-deposited, or a layer of a conventionally known electron-transporting material may be laminated on a layer of a condensed ring fluorene compound.

The organic electroluminescence element may be used as a kind of lamp for illumination or as a light source for exposure, a projection device for projecting an image onto a screen or the like, or a display for directly viewing a still image or a moving image. You may use it as a device (display).

When using an organic electroluminescent element as a display device for reproducing moving images, the driving method may be a simple matrix (passive matrix) method or an active matrix method. Further, by using two or more kinds of organic electroluminescent elements having different emission colors, it is possible to produce a full-color display device.

Although the present disclosure will be described in more detail below based on examples, the present disclosure should not be construed as being limited by these examples.

¹ H-NMR spectra were measured using Gemini200 (manufactured by Varian) or Bruker ASCEND 400 (400 MHz; manufactured by BRUKER).

The glass transition temperature, crystallization temperature, and melting point were measured using DSC7020 (manufactured by Hitachi High-Tech Science, product name).

The DSC measurement conditions are as follows. In addition, the measurement was performed in a nitrogen atmosphere (flow rate of 50 mL/min). First heating, first cooling, and second heating were performed in this order, and the glass transition temperature, crystallization temperature, and melting point during the second heating were taken as the glass transition temperature, crystallization temperature, and melting point of the sample, respectively.

Sample amount: 5 to 10 mg
Measurement condition:
<Fast heating>
Heating rate: 15°C/min
Measurement temperature range: 30°C to 360°C
<Fast Cooling>
Rapid cooling with dry ice <second heating>
Heating rate: 5°C/min
Measurement temperature range: 30°C to 360°C
The luminous properties of the organic electroluminescent device were evaluated by applying a direct current to the fabricated device at room temperature and using a luminance meter (product name: BM-9, manufactured by Topcon Technohouse Co., Ltd.).

Synthesis Example-1 (Synthesis of E1)

Under an argon atmosphere, 2,2'-di(fluoranthene-7-yl)benzophenone (2.48 g, 4.26 mmol) was suspended in methanesulfonic acid (95 mL) and stirred at 120°C for 16 hours. After cooling to 0°C, water and toluene were added, and the organic layer was separated and extracted. The obtained organic layer was concentrated and purified by column chromatography to obtain the target 5,5′-spirobi(indeno[3,2-j]fluoranthene) (compound E1) (yield 1.11 g , yield 46%). The glass transition temperature was 174°C.

¹ H-NMR (400 MHz, CDCl ₃ ): 8.79 (d, J=7.2 Hz, 2H), 8.73 (d, J=8.0 Hz, 2H), 7.85 (dd, J=10 .4Hz, 8.0Hz, 4H), 7.92 (d, J = 8.0Hz, 2H), 7.85 (dd, J = 8.4Hz, 7.2Hz, 2H), 7.74 (d, J = 8.0Hz, 2H), 7.67 (dd, J = 8.4Hz, 7.2Hz, 2H), 7.57 (brdd, J = 15.4Hz, 15.4Hz, 1.2Hz, 2H) , 7.23 (ddd, J=15.4Hz, 15.4Hz, 1.2Hz, 2H), 6.92 (brd, J=7.6Hz, 2H), 6.85 (d, J=7.2Hz , 2H).
Synthesis Example-2 (Synthesis of E2)
Further, the condensed fluorene compounds used in the following experimental examples were synthesized by the same method as the production method shown in Synthetic Example-1. No glass transition point was detected.

¹ H-NMR (400 MHz, CDCl ₃ ): 9.10 (s, 2H), 8.87 (d, J=8.4 Hz, 2H), 8.75 (brd, J=7.2 Hz, 2H), 8.55 (d, J = 7.6Hz, 2H), 8.30 (brdd, J = 7.6Hz, 1.2Hz, 2H), 8.00 (d, J = 7.6Hz, 2H), 7 .73-7.82 (m, 8H), 7.64 (brddd, J = 15.2Hz, 15.2Hz, 1.2Hz, 2H), 7.27-7.31 (m, 2H), 6. 96-7.00 (m, 2H), 6.91 (d, J=7.6Hz, 2H).

Synthesis Example-3 (Synthesis of E6)
Further, the condensed fluorene compounds used in the following experimental examples were synthesized by the same method as the production method shown in Synthetic Example-1. No glass transition point was detected.

¹ H-NMR (400 MHz, CDCl ₃ ): 9.43 (s, 2H), 8.73 (d, J=8.0 Hz, 2H), 8.50 (d, J=8.4 Hz, 2H), 8.42 (d, J=8.4Hz, 2H), 8.25-8.29 (m, 2H), 7.98-8.04 (m, 4H), 7.77 (dd, J=8 .0Hz, 1.2Hz, 2H), 7.62 (brddd, J = 15.6Hz, 15.6Hz, 1.2Hz, 2H), 7.49-7.56 (m, 4H), 7.24 ( brddd, J = 15.2Hz, 15.2Hz, 2.4Hz, 2H), 7.07 (d, J = 8.4Hz, 2H), 6.91 (dd, J = 7.2Hz, 2.0Hz, 2H).

　Synthesis Example-4 (Synthesis of E24)

Under an argon atmosphere, 9-[2-(benzo[b]fluoranthene-7-yl)phenyl],9-hydroxy-9H-fluorene (1.50 g, 2.95 mmol) was treated with ortho-dichlorobenzene (30 mL) and methanesulfone. Suspended in acid (30 mL) and stirred at 120° C. for 1 hour. After cooling to 0°C, water and toluene were added, and the organic layer was separated and extracted. The obtained organic layer was concentrated and purified by column chromatography to obtain the desired compound E24 (1.19 g, 56% yield). The glass transition temperature was 148°C.

¹ H-NMR (400 MHz, CDCl ₃ ): 9.06 (s, 1 H), 8.82 (d, J=8.0 Hz, 1 H), 8.73 (d, J=7.6 Hz, 1 H), 8.52 (d, J = 7.6Hz, 1H), 8.27 (brdd, J = 6.4Hz, 1.6Hz, 1H), 7.98 (d, J = 6.8Hz, 1H), 7 .89 (d, J=8.0Hz, 2H), 7.71-7.80 (m, 4H), 7.61 (ddd, J=15.2Hz, 15.2Hz, 1.2Hz, 1H), 7.40 (ddd, J = 15.2Hz, 15.2Hz, 1.2Hz, 2H), 7.25 (ddd, J = 14.8Hz, 14.8Hz, 0.8Hz, 1H), 7.14 ( ddd, J=15.2Hz, 15.2Hz, 1.6Hz, 2H), 6.83-6.87 (m, 3H), 6.79 (d, J=7.6Hz, 1H).
Synthesis Example-5 (Synthesis of E26)
Further, the condensed fluorene compounds used in the following experimental examples were synthesized by the same method as the production method shown in Synthesis Example-4. The glass transition temperature was 118°C.

¹ H-NMR (400 MHz, CDCl ₃ ): 9.01 (s, 1 H), 8.90 (d, J=5.2 Hz, 1 H), 8.69 (d, J=7.2 Hz, 1 H), 8.50 (d, J = 7.2Hz, 1H), 8.28 (dd, J = 8.0Hz, 8.0Hz, 2H), 8.13 (brd, J = 6.8Hz, 1H), 8 .03 (d, J=7.2 Hz, 1 H), 7.88 (d, J=8.0 Hz, 1 H), 7.79 (dd, J=8.4 Hz, 7.2 Hz, 1 H),7. 73 (ddd, J = 15.2Hz, 15.2Hz, 1.2Hz, 1H), 7.67 (ddd, J = 14.8Hz, 14.8Hz, 1.6Hz, 1H), 7.59 (brdd, J = 14.8Hz, 14.8Hz, 1H), 7.43 (brddd, J = 15.6Hz, 15.6Hz, 0.8Hz, 1H), 3.05 (d, J = 14.8Hz, 4H) , 2.27(s, 2H), 2.04(s, 2H), 1.85(d, J=14.4 Hz, 4H), 1.75(s, 2H).

The structural formulas and abbreviations of the compounds used for the production and performance evaluation of the organic electroluminescent device are shown below.

Device example-1 (see Fig. 2)
(Preparation of substrate 101 and anode 102)
As a substrate having an anode on its surface, a glass substrate with an ITO transparent electrode, in which an indium-tin oxide (ITO) film (thickness: 110 nm) with a width of 2 mm was patterned in stripes, was prepared. Then, after washing the substrate with isopropyl alcohol, the surface was treated by ozone ultraviolet washing.
(Preparation for vacuum deposition)
Each layer was vacuum-deposited on the surface-treated substrate after cleaning by a vacuum deposition method to laminate each layer.

First, the glass substrate was introduced into a vacuum deposition tank, and the pressure was reduced to 1.0×10 ⁻⁴ Pa. Then, each layer was produced in the following order according to the film forming conditions of each layer.
(Preparation of hole injection layer 103)
A hole injection layer 103 was produced by forming a film of 10 nm from sublimation-purified HTL and NDP-9 at a rate of 0.15 nm/sec.
(Preparation of first hole transport layer 1051)
A first hole transport layer 1051 was produced by forming a film of HTL purified by sublimation to a thickness of 85 nm at a rate of 0.15 nm/sec.
(Preparation of second hole transport layer 1052)
Sublimation-purified EBL-1 was deposited at a rate of 0.15 nm/second to a thickness of 5 nm to form a second hole transport layer 1052 .
(Production of light-emitting layer 106)
Sublimation-purified BH-1 and BD-1 were deposited at a ratio of 95:5 (mass ratio) to form a film having a thickness of 20 nm to prepare a light-emitting layer 106 . The deposition rate was 0.18 nm/sec.
(Preparation of first electron transport layer 1071)
Sublimation-purified HBL-1 was deposited at a rate of 0.05 nm/second to a thickness of 6 nm to prepare a first electron transport layer 1071 .
(Preparation of second electron transport layer 1072)
Compound E1 and Liq were deposited at a ratio of 50:50 (mass ratio) to a thickness of 25 nm to form a second electron transport layer 1072 . The deposition rate was 0.15 nm/sec.
(Preparation of cathode 108)
Finally, a metal mask was placed perpendicular to the ITO stripes on the substrate, and a cathode 108 was formed. For the cathode, ytterbium, silver/magnesium (mass ratio 9/1) and silver were deposited in this order to thicknesses of 2 nm, 12 nm and 90 nm, respectively, to form a three-layer structure. The deposition rate of ytterbium was 0.02 nm/second, the deposition rate of silver/magnesium was 0.5 nm/second, and the deposition rate of silver was 0.2 nm/second.

As described above, an organic electroluminescence device 100 having a light emitting area of 4 mm ² as shown in FIG. 2 was produced. Each film thickness was measured with a stylus film thickness meter (DEKTAK, manufactured by Bruker).

Furthermore, this device was sealed in a nitrogen atmosphere glove box with an oxygen and moisture concentration of 1 ppm or less. Sealing was performed by using a bisphenol F type epoxy resin (manufactured by Nagase ChemteX Corporation) between the glass sealing cap and the film formation substrate (element).

A direct current was applied to the organic electroluminescence device produced as described above, and the drive voltage (V) was measured when a current density of 10 mA/cm ² was applied. It should be noted that the current efficiency is a relative value with the result of Device Comparative Example-1 described later as a reference value (100). Table 1 shows the measurement results obtained.

Device example-2
An organic electroluminescence device was produced and evaluated in the same manner as in Device Example-1 except that E2 was used in place of Compound E1 in Device Example-1. Table 1 shows the measurement results obtained.

Device Example-3
An organic electroluminescence device was produced and evaluated in the same manner as in Device Example-1 except that E6 was used in place of Compound E1 in Device Example-1. Table 1 shows the measurement results obtained.

Device Example-4
An organic electroluminescence device was produced and evaluated in the same manner as in Device Example-1 except that E24 was used in place of Compound E1 in Device Example-1. Table 1 shows the measurement results obtained.

Device Example-5
An organic electroluminescence device was produced and evaluated in the same manner as in Device Example-1, except that E26 was used in place of Compound E1 in Device Example-1. Table 1 shows the measurement results obtained.

Device comparison example-1
An organic electroluminescence device was fabricated and evaluated in the same manner as in Device Example-1, except that ETL-1 was used in place of Compound E1 in Device Example-1. Table 1 shows the measurement results obtained.

REFERENCE SIGNS LIST 100 Organic Electroluminescent Device 1 Substrate 2 Anode 3 Hole Injection Layer 4 Hole Transport Layer 41 First Hole Transport Layer 42 Second Hole Transport Layer 5 Light Emitting Layer 6 Electron Transport Layer 7 Electron Injection Layer 8 Cathode 101 Substrate 102 Anode 103 hole injection layer 105 hole transport layer 1051 first hole transport layer 1052 second hole transport layer 106 light emitting layer 107 electron transport layer 1071 first electron transport layer 1072 second electron transport layer 108 cathode Although described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

The specifications, claims, drawings and abstracts of Japanese Patent Application No. 2021-188229 filed on November 18, 2021 and Japanese Patent Application No. 2022-171919 filed on October 27, 2022 is hereby incorporated by reference in its entirety and incorporated as disclosure in the specification of the present invention.

Claims

A condensed fluorene compound represented by formula (1).

In formula (1),
Ring A represents a fluoranthene ring represented by formula (A-1) or an optionally substituted benzofluoranthene ring;

R 1 , R 2 and R′ are each independently
an optionally substituted alkyl group having 1 to 10 carbon atoms, or
(i) an aromatic hydrocarbon group having 6 to 60 carbon atoms, which may be optionally substituted, which is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked;
(ii) a heteroaromatic group having 3 to 60 carbon atoms, or
(iii) an arylamino group having 6 to 60 carbon atoms, or (iv) a group composed of a combination of any two or more selected from the above (i) to (iii);
*1 represents a condensation site;
n is an integer from 0 to 6;
When R 1 and R 2 are an alkyl group having 1 to 10 carbon atoms or an aromatic hydrocarbon group having 6 to 60 carbon atoms, R 1 and R 2 may be linked together to form a ring;
However, when ring A is formula (A-1), R 1 and R 2 are not methyl groups.
Ring B is a monocyclic ring which may be linked, a condensed ring which may be linked, or a structure in which these are linked, which may be optionally substituted (i) an aromatic hydrocarbon having 6 to 20 carbon atoms base, or
(ii) represents a heteroaromatic group having 3 to 20 carbon atoms;
2. The condensed ring fluorene compound according to claim 1, wherein ring A is of formula (A-1) or (A-2).

During the ceremony,
R' and n are as defined in claim 1;
m is an integer from 0 to 4;
In formula (A-2), any two adjacent hydrogens are condensation sites.
The condensed fluorene compound according to claim 1, wherein ring A is formula (A-2).
2. The condensed ring fluorene compound according to claim 1, wherein the compound represented by formula (1) is represented below.
an anode;
a cathode;
and one or more organic thin film layers including at least a light-emitting layer,
An organic electroluminescence device, wherein at least one of the organic thin film layers contains the condensed ring fluorene compound according to any one of claims 1 to 4.