WO2023170880A1 - Dicarbazolyl benzene compound and organic electroluminescent device - Google Patents

Abstract

This dicarbazolyl benzene compound has at least one dicarbazolyl group in which two carbazolyl groups are bonded to each other or at least one substituent dicarbazolyl group to which at least one functional group is bonded. The dicarbazolyl benzene compound includes, as the basic skeleton thereof, a dicarbazolyl benzene in which at least at least one of the dicarbazolyl groups or the at least one substituent dicarbazolyl group is bonded to a benzene ring. The dicarbazolyl benzene compound has the structure represented by structural formula (1).

Description

Dicarbazolylbenzene compounds and organic electroluminescent devices

The present invention relates to dicarbazolylbenzene compounds and organic electroluminescent devices.

In an organic electroluminescent (EL) device, an electron transport layer, a light emitting layer, and a hole transport layer are sandwiched between an anode and a cathode. It is desirable that the organic EL element configured in this manner has a long life. From this point of view, an organic substance suitable as a material for an electron transport layer, a light emitting layer, or a hole transport layer is required. In order to meet this demand, for example, JP 2021-172592A proposes a compound containing a nitrogen-containing heterocycle. In JP-A-2021-172592, the compound is used as a material for an electron transport layer, a light emitting layer, or a hole transport layer.

There is a demand for organic EL to have an even longer lifespan.

The present invention aims to solve the above-mentioned problems.

According to one embodiment of the present invention, two carbazolyl groups have one or more dicarbazolyl groups bonded to each other or one or more substituted dicarbazolyl groups to which one or more functional groups are bonded, Provided is a dicarbazolylbenzene compound having as a basic skeleton a dicarbazolylbenzene in which one or more dicarbazolyl groups or one or more substituted dicarbazolyl groups are bonded to a benzene ring, and is represented by the following structural formula (1). be done.

Here, R2 to R5 in Structural Formula (1) represent a substituent bonded to any position of the benzene ring constituting the carbazolyl group. R2 to R5 may be hydrogen.

At least one of L1 to L3 in the above structural formula (1) is a functional group represented by the following structural formula (2), structural formula (3), or structural formula (4).

n in the above structural formula (2) is 0 or 1.
R6 and R7 are substituted aromatic hydrocarbon groups or unsubstituted aromatic hydrocarbon groups, or substituted nitrogen-containing aromatic heterocyclic groups or unsubstituted nitrogen-containing aromatic heterocyclic groups.

R8 in the above structural formula (3) is hydrogen, a substituted aromatic hydrocarbon group, or an unsubstituted aromatic hydrocarbon group.

R9 and R10 in the above structural formula (4) are hydrogen. Alternatively, R9 and R10 may be substituted or unsubstituted aromatic hydrocarbon groups.

When at least one of R2 to R5 is a monovalent aromatic hydrocarbon group, at least one of L1 to L3 is a substituted aromatic hydrocarbon or an unsubstituted aromatic hydrocarbon, or It is a substituted aromatic heterocyclic group or an unsubstituted aromatic heterocyclic group.

According to another embodiment of the present invention, an organic electroluminescent device is provided that includes a layer containing the dicarbazolylbenzene compound described above.

Note that hydrogen in each compound may be replaced with deuterium. The deuteration rate may be high, for example, about 80%.

In the above compounds, the energy of the first excited triplet state (T1) is high. Further, the highest occupied level (HOMO) and lowest unoccupied level (LUMO) of the above-mentioned compound are within appropriate ranges when used as a charge transport material, especially when a blue light emitting material is included in the light emitting layer. In addition, in this compound, the charge easily moves within the molecule, so that it is difficult for the charge to become delocalized. Therefore, the molecular structure is stabilized. Furthermore, since intramolecular rotation is suppressed based on the molecular structure, thermal stability is good.

For the reasons mentioned above, an organic electroluminescent element including a layer containing the above compound has a longer lifespan.

FIG. 1 is a schematic side view of an organic EL element. FIG. 2 is a chart showing various physical properties of dicarbazolylbenzene compounds. FIG. 3 is a chart showing various characteristics of an organic EL element having a light emitting layer containing an organic substance. FIG. 4 is a chart showing various characteristics of an organic EL element having a layer containing an organic substance.

FIG. 1 is a schematic side view of an organic electroluminescence (EL) element 10. The organic EL element 10 includes a glass substrate 12, an anode 14, a hole transport layer 16, a light emitting layer 18, an electron transport layer 20, and a cathode 22. As materials for the glass substrate 12, anode 14, and cathode 22, known materials can be used.

At least one of the hole transport layer 16, the light emitting layer 18, or the electron transport layer 20 contains a dicarbazolylbenzene compound. In the present embodiment, the dicarbazolylbenzene compound refers to a compound containing as a basic skeleton a benzene ring to which one or more dicarbazolyl groups are bonded, each having two carbazolyl groups bonded to each other. Alternatively, a dicarbazolylbenzene compound refers to a compound containing as a basic skeleton a benzene ring to which one or more substituted dicarbazolyl groups are bonded. The structural formula of the dicarbazolylbenzene compound according to this embodiment is shown in the following structural formula (1).

R2 to R5 in the above structural formula (1) represent hydrogen or a substituent bonded to any position of the benzene ring constituting the carbazolyl group. Furthermore, at least one of L1 to L3 in the above structural formula (1) is a functional group represented by the following structural formula (2), structural formula (3), or structural formula (4).

n in the above structural formula (2) is 0 or 1. When n=0, structural formula (1) is transformed into the following structural formula. In this case, N is bonded to the benzene ring in structural formula (1).

On the other hand, when n=1, N is bonded to the benzene ring in structural formula (1) via a phenyl group.

6 and R7 in structural formula (2) represent a substituted or unsubstituted aromatic hydrocarbon group. Alternatively, R6 and R7 may be substituted or unsubstituted nitrogen-containing aromatic heterocyclic groups. Representative examples of the nitrogen-containing aromatic heterocyclic group include a nitrogen-containing 5-membered ring group, a nitrogen-containing 6-membered ring group, a nitrogen-containing aromatic condensed two-ring group, and a nitrogen-containing aromatic condensed three-ring group. Specific examples of the nitrogen-containing 5-membered cyclic group include a pyrrolyl group, and specific examples of the nitrogen-containing 6-membered cyclic group include a pyridinyl group or a pyrimidyl group. Specific examples of the nitrogen-containing aromatic condensed two rings include an indolyl group and a quinolyl group, and specific examples of the nitrogen-containing aromatic condensed three rings include a carbazolyl group and a phenanthrolyl group. The nitrogen-containing aromatic heterocyclic group is not particularly limited to the above-mentioned substituents.

R8 in Structural Formula (3) represents a substituted or unsubstituted aromatic hydrocarbon group. Alternatively, R8 may be a substituted or unsubstituted nitrogen-containing aromatic heterocyclic group.

R9 and R10 in structural formula (4) are hydrogen. Alternatively, R9 and R10 may be substituted or unsubstituted aromatic hydrocarbon groups.

All of R2 to R5 may be hydrogen. Specific examples of L1 to L3 in this case will be shown below.

[1. Example of L1 when L2=L3=H]

[2. Example of L1 and L3 when L2=H]

[3. Example of L2 when L1=L3=H]

Note that Me represents a methyl group.

The dicarbazolylbenzene compound may be a compound in which two dicarbazolyl groups or two substituted dicarbazolyl groups are bonded to a benzene ring. Furthermore, any one of L1 to L3 bonded to the benzene ring is preferably a carbazolyl group or a substituted carbazolyl group. The structural formula of this compound is illustrated below. Note that this structural formula exemplifies a compound in which two dicarbazolyl groups and one carbazolyl group are bonded to a benzene ring. That is, in this compound, hydrogen contained in the dicarbazolyl group and the carbazolyl group is not substituted with a substituent.

The dicarbazolylbenzene compound may be a compound in which two dicarbazolyl groups, two substituted dicarbazolyl groups, or one dicarbazolyl group and one substituted dicarbazolyl group are bonded to a benzene ring. . Two dicarbazolyl groups, two substituted dicarbazolyl groups, or one dicarbazolyl group and one substituted dicarbazolyl group are preferably at the ortho position (o-position) in the benzene ring.

The structural formula of this compound is illustrated below. Note that this structural formula exemplifies a compound in which two dicarbazolyl groups are bonded to a benzene ring. That is, in this compound, hydrogen contained in the dicarbazolyl group is not substituted with a functional group. Further, the two dicarbazolyl groups are positioned at the o-position in the benzene ring.

The dicarbazolylbenzene compound may be a compound in which two dicarbazolylbenzenes are bonded to each other. Here, one dicarbazolylbenzene is a compound in which a dicarbazolyl group or a substituted dicarbazolyl group is bonded to a benzene ring. Therefore, the dicarbazolylbenzene compound in this case has a form in which a functional group containing a phenyl group is bonded to dicarbazolylbenzene. A functional group containing a phenyl group refers to a functional group in which a dicarbazolyl group or a substituted dicarbazolyl group is bonded to a phenyl group. The dicarbazolyl group or substituted dicarbazolyl group in dicarbazolylbenzene and the functional group containing a phenyl group are preferably o-positioned in the benzene ring.

The structural formula of this compound is illustrated below. Note that this structural formula exemplifies a compound in which two dicarbazolylbenzenes are bonded to each other. That is, in this compound, hydrogen contained in the dicarbazolyl group is not substituted with a functional group. Furthermore, the dicarbazolyl group and the functional group containing the phenyl group are in a positional relationship such that they are at the o-position in the benzene ring.

Alternatively, R2 to R5 may be monovalent aromatic hydrocarbon groups. In this case, at least one of L1 to L3 is a monovalent substituted aromatic hydrocarbon group or a monovalent unsubstituted aromatic hydrocarbon group. At least one of L1 to L3 may be a monovalent substituted aromatic heterocyclic group or a monovalent unsubstituted aromatic heterocyclic group.

When the hole transport layer 16, the light emitting layer 18, or the electron transport layer 20 containing the dicarbazolylbenzene compound having the above structure as a material is formed, the organic EL element 10 having the layer is different from the conventional technology. It is recognized that the lifespan is longer than that of such organic EL elements.

The reason why the lifespan becomes longer in this way is thought to be as follows. First, in these compounds, the energy of the first excited triplet state (T1) is high, and the highest occupied level (HOMO) and lowest unoccupied level (LUMO) are appropriate. Second, according to the structural formula, it is easy for charges to move within the molecule, and the charges are difficult to delocalize, so the molecular structure is stabilized. Thirdly, since intramolecular rotation is suppressed based on the molecular structure, it has good thermal stability and is suitable as a host.

Furthermore, when the plurality of functional groups described above are positioned at the o-position on the benzene ring, the molecule forms a sterically twisted structure. This limits the extent of the π conjugate. As a result, wide gaps in energy tend to occur. Such a compound is considered to be more suitable as a material for blue light emission.

Note that the present invention is not limited to the embodiments described above, and can take various configurations without departing from the gist of the present invention.

For example, hydrogen in the organic compound described above may be replaced with deuterium. The deuteration rate may be high, for example, about 80%.

Further, dicarbazolylbenzene compounds can have various structures by bonding substituted aromatic hydrocarbon groups or substituted aromatic heterocyclic groups.

[Synthesis of compounds]
Ac, Bu, Et and Ar in the following represent an acetyl group, a butyl group, an ethyl group and an aryl group, respectively. Further, t-Bu means a tertiary butyl group. Furthermore, "%" of H, C and N is mass %.

[Example 1]
For 5 ml of mesitylene, 2 mmol of dicarbazole, 2 mmol of 9-(3-bromophenyl)-9H-carbazole, 0.04 mmol of Pd(OAc) ₂ and 0.16 mmol of t- Bu ₃ P and 3 mmol of NaO(t-Bu) were added to prepare a mixed solution. The mixture was stirred for 4 hours while being maintained at 150° C. under an argon atmosphere. The mixture was quenched by adding 3 milliliters of 1 mol/liter HCl, and the organic matter was extracted from the mixture using EtOAc. After washing the organic matter with saturated brine, the organic matter was dried with MgSO ₄ . The solvent was removed under reduced pressure to obtain the crude product.

The crude product was passed through Florisil using ethyl acetate as a developing solvent, and then the solvent was removed under reduced pressure and recrystallized using 2-propanol to obtain a whitish-brown organic substance. The yield was 1.13 g, and the yield was 98%.

The obtained organic matter was analyzed using an organic trace element analyzer. C, H and N in the molecule were 87.82%, 5.07% and about 6.93%, respectively. Further, the analysis results by nuclear magnetic resonance (NMR) were as follows.
¹ HNMR (DMSO-d6, 392MHz); δ = 6.64-6.71 (m, 3H), 6.80-6.92 (m, 4H), 7.00-7.03 (m, 2H) , 7.13-7.25 (m, 5H), 7.33-7.52 (m, 7H), 7.59 (d, J = 7.6Hz, 1H), 8.03 (d, J = 7.6Hz, 1H), 8.12 (d, J = 7.6Hz, 2H), 8.37 (d, J = 7.6Hz, 1H), 8.5 (d, J = 7.6Hz, 1H) ).

From the above results, it was determined that the specific formula of the obtained organic substance was C ₄₂ H ₂₇ N ₃ and the molecular weight was 573.7.

The chemical reaction formula in this case is shown below.

Hereinafter, the organic substance that is the product will be referred to as DCZ-1.

[Example 2]
For 2.7 ml of mesitylene, 0.33 g of dicarbazole, 0.49 g of Ar-Br (aryl bromide), 4.5 mg of Pd(OAc) ₂ and 16.2 mg of t-Bu ₃ P and 0.144 g of NaO(t-Bu) were added to prepare a mixed solution. The mixture was maintained at 150°C and stirred under an argon atmosphere. The aryl bromide used was 9,9'-(5-bromo-1,3-phenylene)bis(9H-carbazole), and its structural formula is as follows.

The mixture was quenched by adding 1.5 milliliters of 1 mol/liter HCl, and the organic matter was extracted from the mixture using EtOAc. After washing the organic matter with saturated brine, the organic matter was dried with MgSO ₄ . The solvent was removed under reduced pressure to obtain the crude product. Next, the crude product was purified by silica gel column using ethyl acetate as a developing solvent. The obtained purified product was reprecipitated with ethanol to obtain a white solid organic substance. The yield was 0.66 g, and the yield was 89%. After washing the organic matter with pure water and saturated brine, the organic matter was dried with MgSO ₄ .

Thereafter, the obtained organic substances were analyzed in the same manner as in Example 1. C, H and N in the molecule were 87.63%, 4.60% and 7.51%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (DMSO-d6, 392MHz); δ = 6.67-6.70 (m, 2H), 6.83-6.88 (m, 4H), 7.11-7.13 (m, 4H) , 7.22-7.23 (m, 2H), 7.25-7.33 (m, 5H), 7.39-7.60 (m, 11H), 8.17-8.19 (m, 4H), 8.44-8.46 (m, 1H), 8.55-8.57 (m, 1H).
From the above results, it was determined that the formula of the obtained organic substance was C ₅₄ H ₃₄ N ₄ and the molecular weight was 738.89. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-2.

[Example 3]
A white color was prepared in the same manner as in Example 2 except that 0.47 g of 9-(3-bromophenyl)-3,6-diphenyl-9H-carbazole whose structural formula is shown below was used and hexane and EtOAc were used as the developing solvents. A solid organic material was obtained. The yield was 0.33 g, and the yield was 75%.

C, H, and N in the molecule determined by an organic trace element analyzer were 89.20%, 4.91%, and 5.72%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (DMSO-d6, 392MHz); δ = 6.70-7.32 (m, 12H), 7.39-7.45 (m, 4H), 7.49-7.56 (m, 7H) , 7.70-7.73 (m, 1H), 7.80-7.86 (m, 6H), 8.12-8.15 (m, 1H), 8.42-8.44 (m, 1H), 8.54-8.56 (m, 1H), 8.65-8.66 (m, 2H).
From the above results, it was determined that the specific formula of the obtained organic substance was C ₅₄ H ₃₅ N ₃ and the molecular weight was 725.9. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-3.

[Example 4]
A white solid organic substance was obtained in the same manner as in Example 3 except that 0.66 g of 1,3-dibromobenzene was used. Note that dicarbazole, Pd(OAc) ₂ , t-Bu ₃ P, and NaO(t-Bu) were 0.66 g, 9 mg, 32.4 mg, and 0.29 g, respectively, and mesitylene was 4 ml. In addition, chloroform was used for extraction. Chloroform was also used as the developing solvent. The yield was 0.44 g, and the yield was 59%.

C, H, and N in the molecule determined by an organic trace element analyzer were 87.73%, 4.76%, and 7.58%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 5.86-5.87 (m, 1H), 6.34-6.38 (m, 3H), 6.50-6.62 (m, 6H), 6.74-6.78 (m, 4H), 6.90-7.00 (m, 6H), 7.19-7.32 (m, 4H), 7.48-7.60 (m, 6H) ), 8.18-8.22 (m, 4H).
From the above results, it was determined that the formula of the obtained organic substance was C ₅₄ H ₃₄ N ₄ and the molecular weight was 738.89. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-4.

[Example 5]
A white solid organic substance was obtained in the same manner as in Example 1, except that 1 mmol of 9-(3,5-dibromophenyl)-9H-carbazole having the structural formula shown below was used. Note that dicarbazole, Pd(OAc) ₂ , t-Bu ₃ P, and NaO(t-Bu) were set at 2 mmol, 0.04 mmol, 0.16 mmol, and 3 mmol, respectively, and mesitylene was set at 5 ml. . The yield was 0.81 g, and the yield was 90%.

C, H, and N in the molecule determined by an organic trace element analyzer were 87.98%, 4.69%, and 7.65%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.09 (s, 1H), 6.35 (dd, J = 7.2, 7.2Hz, 2H), 6.54-6.64 (m, 6H ), 6.74-6.81 (m, 4H), 6.9 (s, 2H), 7.00-7.06 (m, 6H), 7.21-7.29 (m, 4H), 7.35-7.38 (m, 8H), 7.56 (d, J=7.2Hz, 2H), 8.05 (d, J=7.2Hz, 2H), 8.20-8.23 (m, 4H).
From the above results, it was determined that the specific formula of the obtained organic substance was C ₆₆ H ₄₁ N ₅ and the molecular weight was 904.09. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-6.

[Example 6]
A white solid organic substance was obtained in the same manner as in Example 4, except that 1 mmol of N,N-bis(4-biphenylyl)-N-(4-bromophenyl)amine whose structural formula is shown below was used. . Note that dicarbazole, Pd(OAc) ₂ , t-Bu ₃ P, and NaO(t-Bu) are 1 mmol, 0.02 mmol, 0.08 mmol, and 1.5 mmol, respectively, and mesitylene is 4 ml. And so. The yield was 0.46 g, and the yield was 63%.

C, H, and N in the molecule determined by an organic trace element analyzer were 89.19%, 5.20%, and 5.56%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.30 (d, J = 8.5 Hz, 2H), 6.58 (d, J = 8.5 Hz, 2H), 6.84 (d, J = 8 .5Hz, 4H), 7.04 (d, J = 8.5Hz, 2H), 7.11 (d, J = 8.5Hz, 1H), 7.20-7.24 (m, 2H), 7 .25-7.50 (m, 16H), 7.59 (d, J = 7.2Hz, 4H), 8.08 (d, J = 7.6Hz, 2H), 8.22 (d, J = 7.6Hz, 1H), 8.32 (d, J=7.2Hz, 1H).
From the above results, it was determined that the formula of the obtained organic substance was C ₅₄ H ₃₇ N ₃ and the molecular weight was 727.91. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-9.

[Example 7]
A white solid organic substance was obtained in the same manner as in Example 5 except that 4'-bromotri(4-biphenylyl)amine having the structural formula shown below was used. The molar ratios of dicarbazole, 4'-bromotri(4-biphenylyl)amine, Pd(OAc) ₂ , t-Bu ₃ P and NaO(t-Bu) are the same as in Example 5. Note that the amount of mesitylene was 2.5 ml. The yield was 0.72 g, and the yield was 89%.

H, C, and N in the molecule determined by an organic trace element analyzer were 5.27%, 89.67%, and 5.43%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.51 (s, 4H), 7.01 (d, J = 8.1 Hz, 2H), 7.06-7.23 (m, 8H), 7. 26-7.37 (m, 8H), 7.42-7.63 (m, 15H), 7.77 (d, J = 7.6Hz, 2H), 8.23 (d, J = 7.2Hz) , 1H), 8.34 (d, J = 8.1Hz, 1H).
From the above results, it was determined that the specific formula of the organic substance obtained was C ₆₀ H ₄₁ N ₃ and the molecular weight was 809.01. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-10.

[Example 8]
A white solid organic substance was prepared in the same manner as in Example 2 except that 1 mmol of N-(4-bromophenyl)-N-(naphthalen-2-yl)naphthalen-2-amine whose structural formula is shown below was used. Obtained. Note that the amount of ethylene was 2.7 ml. The yield was 0.60 g, and the yield was 88%.

H, C, and N in the molecule determined by an organic trace element analyzer were 89.03%, 4.96%, and 6.05%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.25-6.29 (m, 2H), 6.53-6.57 (m, 2H), 7.03-7.06 (m, 4H), 7.10-7.50 (m, 15H), 7.60-7.63 (m, 2H), 7.76-7.81 (m, 4H), 8.12-8.14 (m, 2H) ), 8.22-8.24 (m, 1H), 8.32-8.34 (m, 1H).
From the above results, it was determined that the formula of the obtained organic substance was C ₅₀ H ₃₅ N ₃ and the molecular weight was 675.84. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-11.

[Example 9]
Except for using 1 mmol of N-(4'-bromo-[1,1'-biphenyl]-4-yl)-N-(naphthalen-2-yl)-naphthalen-2-amine whose structural formula is shown below. A white solid organic substance was obtained in the same manner as in Example 8, including the amount of mesitylene. The yield was 0.65 g, and the yield was 87%.

C, H and N in the molecule determined by an organic trace element analyzer were 89.54%, 5.04% and 5.29%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.52-6.53 (m, 4H), 6.99-7.02 (m, 2H), 7.08-7.19 (m, 8H), 7.25-7.58 (m, 13H), 7.64-7.66 (m, 2H), 7.77-7.83 (m, 6H), 8.22-8.24 (m, 1H) ), 8.33-8.36 (m, 1H).
From the above results, it was determined that the specific formula of the obtained organic substance was C ₅₆ H ₃₇ N ₃ and the molecular weight was 751.93. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-12.

[Example 10]
The amount of mesitylene was also included, except that 0.474 g, equivalent to 1 mmol, of 9-(4-bromophenyl)-3,6-diphenyl-9H-carbazole, whose structural formula is shown below, was used as the aryl bromide. In the same manner as in Example 9, a white solid organic substance was obtained. The yield was 0.52 g, and the yield was 71%.

C, H and N in the molecule determined by an organic trace element analyzer were 89.43%, 4.98% and 5.87%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.78-6.80 (m, 2H), 6.94-6.96 (m, 2H), 7.12-7.62 (m, 19H), 7.71-7.77 (m, 6H), 7.95-7.97 (m, 2H), 8.28-8.39 (m, 4H).
From the above results, it was determined that the specific formula of the obtained organic substance was C ₅₄ H ₃₅ N ₃ and the molecular weight was 725.9. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-13.

[Example 11]
1 mmol of 9-(4'-bromo-[1,1'-biphenyl]-4-yl)-3,6-diphenyl-9H-carbazole whose structural formula is shown below was used, and ethylene was set at 5 ml. A white solid organic substance was obtained in the same manner as in Example 10 except for this. The yield was 0.70 g, and the yield was 88%.

C, H, and N in the molecule determined by an organic trace element analyzer were 89.93%, 4.99%, and 5.03%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.61-6.66 (m, 4H), 7.04-7.21 (m, 4H), 7.31-7.86 (m, 27H), 8.25-8.44 (m, 4H).
From the above results, it was determined that the formula of the obtained organic substance was C ₆₀ H ₃₉ N ₃ and the molecular weight was 801.99. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-14.

[Example 12]
As the dicarbazole compound, 0.64 g, equivalent to 1 mmol, of 3,3',6,6'-tetraphenyl-9H-1,9'-bicarbazole whose structural formula is shown below was used.

Further, as the aryl bromide, 0.233 g of 4-bromobiphenyl whose structural formula is shown below was used, which corresponds to 1 mmol.

Thereafter, a white solid organic substance was obtained in the same manner as in Example 11, except that the amount of ethylene was changed to 2.5 ml. The yield was 0.48 g, and the yield was 61%.

C, H, and N in the molecule determined by an organic trace element analyzer were 91.19%, 5.16%, and 3.49%, respectively. Further, the results of NMR analysis are as follows.
¹ HNMR (CDCl ₃ , 392 MHz); δ = 6.62-6.67 (m, 4H), 7.14-7.64 (m, 27H), 7.73-7.75 (m, 2H), 7.83-7.85 (m, 2H), 7.92-7.93 (m, 1H), 8.01-8.02 (m, 2H), 8.50-8.51 (m, 1H) ), 8.65-8.66 (m, 1H).
From the above results, it was determined that the formula of the obtained organic substance was C ₆₀ H ₃₉ N ₃ and the molecular weight was 801.99. The structural formula of the organic substance in this case is shown below.

Hereinafter, this organic substance will be referred to as DCZ-15.

[Example 13]
A mixed solution was prepared in the same manner as in Example 1 except that 1 mmol of 3,3'-dibromobiphenyl was used in place of 9-(3-bromophenyl)-9H-carbazole. The mixture was stirred for 4 hours while being maintained at 150° C. under an argon atmosphere. The mixture was quenched by adding 1 mol/liter of HCl, and extracted with chloroform. After washing the organic layer with water, the organic layer was washed with saturated brine. The organics were then dried with _MgSO4 . The solvent was removed under reduced pressure to obtain the crude product.

The crude product was purified on a silica gel column using a 5:1 mixture of hexane/ethyl acetate as a developing solvent to obtain a white solid organic substance. The yield was 0.55 g, and the yield was 68%.

The results of NMR analysis of the obtained organic matter were as follows.
¹ HNMR (DMSO-d6, 392MHz); δ = 4.67 (s, 2H), 5.05 (t, J = 7.3Hz, 2H), 5.64 (t, J = 7.6Hz, 2H) , 6.59-6.90 (m, 12H), 7.07-7.23 (m, 6H), 7.45-7.59 (m, 10H), 8.55-8.66 (m, 4H).

From the above results, it was determined that the formula of the obtained organic substance was C ₆₀ H ₃₈ N ₄ and the molecular weight was 814.

The chemical reaction formula in this case is shown below.

Hereinafter, the organic substance that is the product will be referred to as DCZ-20.

[Physical property evaluation of organic substances (dicarbazolylbenzene compounds)]
The glass transition temperature (Tg ), HOMO, LUMO, S1, T1, absorption edge, maximum fluorescence wavelength, quantum yield, and oxidation potential were determined. The results are collectively shown in FIG. 2. The glass transition temperatures of all of the above compounds are 100°C or higher. Therefore, these compounds are suitable as materials for each layer of an organic EL element.

From FIG. 2, it can be seen that the energy of the first excited triplet state (T1) of each compound is high. In addition, the HOMO energy (EHOMO) and lowest unoccupied level energy (ELUMO) of each compound are within appropriate ranges, especially when used as a charge transport material when a blue light emitting material is included in the light emitting layer.

[Element evaluation part 1]
Organic EL devices each having a structure shown in FIG. 1 and having a light emitting layer containing DCZ-9 or DCZ-10 as a host material were manufactured. For comparison, an organic EL element having the structure shown in FIG. 1 was prepared, including a light-emitting layer containing URP or 3,3'-di(9H-carbazol-9-yl)-1,1'-biphenyl as a host material. Each was produced. Hereinafter, 3,3'-di(9H-carbazol-9-yl)-1,1'-biphenyl will be referred to as m-CBP.

The lifetime of each organic EL element was evaluated by causing it to emit fluorescence, phosphorescence, or thermally activated delayed fluorescence (TADF). Note that the lifetime is the time until the emission intensity decreases to 90% of the initial characteristic. The results are also shown in FIG. From FIG. 3, it can be seen that the lifetime of the organic EL device using DCZ-9 or DCZ-10 as the host material for the emissive layer is superior to that of the organic EL device using URP or m-CBP as the host material for the emissive layer. I know that there is.

Although not particularly shown in FIG. 3, in the case of emitting fluorescence, an organic EL device using DCZ-9 or DCZ-10 as the host material of the emitting layer is different from an organic EL device using URP as the host material of the emitting layer. It showed better efficiency than EL devices.

[Element evaluation part 2]
Nine types of organic EL devices having a hole injection layer (HIL), a hole transport layer (HTL), an electron block layer (EBL), and a hole block layer (HBL) were fabricated. Hereinafter, the nine types of organic EL elements will be referred to as evaluation elements 1 to 9, respectively. The substances shown in FIG. 4 were used as organic compounds contained in HIL, HTL, EBL, and HBL in Evaluation Elements 1 to 9. As shown in FIG. 4, in evaluation elements 1 to 9, DCZ-9 or DCZ-10 is included in at least one of the HIL, HTL, EBL, and HBL layers.

Note that OPDA-10 contained in HTL of evaluation element 2 and HIL of evaluation element 5, respectively, is an organic compound whose chemical structural formula is shown below.

For these evaluation elements 1 to 9, the efficiency, the time until the emission intensity decreases to 90% of the initial characteristics (lifetime), and the change in voltage until the emission intensity decreases to 90% of the initial characteristics (ΔV ) was evaluated. The results are also shown in FIG.

For comparison, two types of organic EL devices were fabricated that did not have any layer containing an organic compound such as DCZ-1. Hereinafter, the two types of organic EL elements will be referred to as control element 1 and control element 2, respectively. Note that organic compounds contained in HIL, HTL, EBL, and HBL in control element 1 and control element 2 are shown in FIG. 4.

Efficiency, lifetime, and ΔV were also evaluated for Control Element 1 and Control Element 2. The results are also shown in FIG.

From FIG. 4, it can be seen that Evaluation Elements 1 to 9 having layers containing DCZ-9 or DCZ-10 have better lifetimes than Control Elements 1 and 2 that do not have layers containing DCZ-9 or DCZ-10. It can be seen that this shows that Furthermore, the efficiency of Evaluation Elements 1 to 9 is approximately equal to or higher than that of Comparative Element 1 and Comparative Element 2. As described above, the organic EL elements (Evaluation Elements 1 to 9) having layers containing DCZ-9 or DCZ-10 are equivalent to the organic EL elements according to the prior art (Control Element 1 and Control Element 2). Demonstrates efficiency and excellent longevity.

DESCRIPTION OF SYMBOLS 10...Organic EL element 12...Glass substrate 14...Anode 16...Hole transport layer 18...Light emitting layer 20...Electron transport layer 22...Cathode

Claims (8)

1. Two carbazolyl groups have one or more dicarbazolyl groups bonded to each other, or one or more substituted dicarbazolyl groups to which one or more functional groups are bonded, and the one or more dicarbazolyl groups or the one or more A dicarbazolylbenzene compound containing as a basic skeleton a dicarbazolylbenzene in which a substituted dicarbazolyl group is bonded to a benzene ring, and is represented by the following structural formula (1).
   

   

   R2 to R5 in the above structural formula (1) represent hydrogen or a substituent bonded to any position of the benzene ring constituting the carbazolyl group. Furthermore, at least one of L1 to L3 in the above structural formula (1) is a functional group represented by the following structural formula (2), structural formula (3), or structural formula (4).
   

   

   n in the above structural formula (2) is 0 or 1.
   R6 and R7 are substituted aromatic hydrocarbon groups or unsubstituted aromatic hydrocarbon groups, or substituted nitrogen-containing aromatic heterocyclic groups or unsubstituted nitrogen-containing aromatic heterocyclic groups.
   

   

   R8 in the above structural formula (3) is hydrogen, a substituted aromatic hydrocarbon group, or an unsubstituted aromatic hydrocarbon group.
   

   

   When at least one of R2 to R5 is a monovalent aromatic hydrocarbon group, at least one of L1 to L3 is a substituted aromatic hydrocarbon or an unsubstituted aromatic hydrocarbon, or It is a substituted aromatic heterocyclic group or an unsubstituted aromatic heterocyclic group.
2. 2. The dicarbazolylbenzene compound according to claim 1, wherein the one or more dicarbazolyl groups are two dicarbazolyl groups bonded to the benzene ring, or the one or more substituted dicarbazolyl groups are two substituted dicarbazolyl groups. A dicarbazolylbenzene compound in which a group is bonded to the benzene ring, or one dicarbazolyl group and one substituted dicarbazolyl group are bonded to the benzene ring.
3. The dicarbazolylbenzene compound according to claim 2, wherein a carbazolyl group or a substituted carbazolyl group is further bonded to the benzene ring.
4. In the dicarbazolylbenzene compound according to claim 2, the two dicarbazolyl groups, the two substituted dicarbazolyl groups, or the one dicarbazolyl group and the one substituted dicarbazolyl group are o- Dicarbazolylbenzene compounds in positional relationship.
5. In the dicarbazolylbenzene compound according to claim 1, a functional group in which a dicarbazolyl group or a substituted dicarbazolyl group is bonded to a phenyl group is bonded to a dicarbazolylbenzene in which a dicarbazolyl group or a substituted dicarbazolyl group is bonded to a benzene ring. dicarbazolylbenzene compounds.
6. The dicarbazolylbenzene compound according to claim 5, wherein the functional group is at the o-position with respect to the dicarbazolyl group or the substituted dicarbazolyl group.
7. The dicarbazolylbenzene compound according to claim 1, wherein at least one of L1 to L3 is a functional group containing N.
8. An organic electroluminescent device (10) comprising a layer containing the dicarbazolylbenzene compound according to any one of claims 1 to 7.

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