A nitrogen-containing heterocyclic compound with o-phenanthroline as a mother nucleus, and a preparation method and application thereof

Abstract

The application discloses a kind of nitrogen-containing heterocyclic compounds with o-phenanthroline as parent nucleus, structural general formula is as shown in formula I: Wherein, X1-X3 each independently selected from C or N, and the number of N is at least 1;L1 and L2 each independently selected from any one of connecting bond, substituted or unsubstituted C6-C30 aryl and substituted or unsubstituted 3 to 30 heteroaromatic group;Ar1 and Ar2 each independently selected from any one of substituted or unsubstituted C6-C30 aryl and substituted or unsubstituted 3 to 30 heteroaromatic group;The electronic transport material of the application makes the organic electroluminescent device prepared therefrom has the performance advantages of low driving voltage, high efficiency and long service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic light-emitting materials, in particular to a nitrogen-containing heterocyclic compound with o-phenanthroline as a mother nucleus and a preparation method and application thereof. BACKGROUND

[0002] An organic light emitting diode (OLED) is a promising display technology that gradually enters people's field of vision. The OLED is an electroluminescent device formed by a plurality of organic thin film structures. The organic electroluminescent element is a self-luminous element using the following principle: by applying an electric field, the fluorescence substance is made to emit light by the recombination energy of the hole injected from the anode and the electron injected from the cathode.

[0003] It has the following structure: anode, cathode and organic material layer between the two. In order to improve the efficiency and stability of the organic electroluminescent element, the organic material layer usually includes multiple layers with different materials, such as hole injection layer (HIL), hole transport layer (HTL), light emitting layer, electron transport layer (ETL) and electron injection layer (EIL). In such an organic light emitting element, when a voltage is applied between the anode and the cathode, the holes from the anode and the electrons from the cathode are injected into the organic material layer, and the generated excitons produce light with a specific wavelength when migrating to the ground state.

[0004] The electron transport layer is a key component in the OLED structure, responsible for regulating the injection speed and amount of electrons. The structure of the electron transport material currently used as the electron transport layer usually contains electron-withdrawing groups such as pyridine, pyrimidine, oxadiazole, triazole, imidazole and other nitrogen-containing heterocycles, but the electron mobility of general organic materials is low, while the hole mobility is high, which causes the electron-hole imbalance in the light emitting device, resulting in low device efficiency, poor stability, short life and other problems.

[0005] In order to solve the above problems, therefore, how to provide an organic electroluminescent device with high mobility electron transport material has low driving voltage, high efficiency and long life is a problem that needs to be solved by those skilled in the art. SUMMARY

[0006] Therefore, the present application provides a nitrogen-containing heterocyclic compound with o-phenanthroline as a mother nucleus and a preparation method and application thereof. The organic electroluminescent device prepared by the electron transport material has the performance advantages of low driving voltage, high efficiency and long life.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0008] A nitrogen-containing heterocyclic compound having o-phenanthroline as a mother nucleus, a structural general formula of the nitrogen-containing heterocyclic compound is shown as formula I:

[0009]

[0010] wherein X1-X3 are each independently selected from C or N, and the number of N is at least 1;

[0011] L1 and L2 are each independently selected from any one of a bond, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted 3- to 30-membered heteroaryl group;

[0012] Ar1 and Ar2 are each independently selected from any one of a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted 3- to 30-membered heteroaryl group;

[0013] R' is any one of a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C1-C6 alkoxy group, a substituted or unsubstituted C3-C12 cycloalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C10-C30 fused ring group, and a substituted or unsubstituted 3- to 30-membered heteroaryl group;

[0014] n is an integer selected from 1-5.

[0015] Preferably, L1 and L2 are each independently selected from any one of a bond, a substituted or unsubstituted C6-C18 aryl group, and a substituted or unsubstituted 3- to 18-membered heteroaryl group.

[0016] Preferably, Ar1 and Ar2 are each independently selected from any one of a substituted or unsubstituted C6-C18 aryl group, and a substituted or unsubstituted 3- to 18-membered heteroaryl group.

[0017] Preferably, R' is any one of deuterium, a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C1-C3 alkoxy group, a substituted or unsubstituted C6-C18 aryl group, a substituted or unsubstituted C10-C18 fused ring group, and a substituted or unsubstituted 3- to 18-membered heteroaryl group; and n is an integer selected from 1-3.

[0018] Preferably, the heteroatom in the heteroaryl group is at least one of N, O, S, Si, P, and Se.

[0019] Preferably, the structural general formula I of the nitrogen-containing heterocyclic compound is:

[0020]

[0021] wherein R1, R2, R3, R4, and R5 are the same as the structure of R'.

[0022] Preferably, the R1-R5 are substituted at any available position, each independently selected from the group consisting of hydrogen, deuterium, methyl, ethyl, t-butyl, methoxy, and the following groups or any combination thereof:

[0023]

[0024] Preferably, the L1, L2, Ar1, and Ar2 are substituted at any available position, each independently selected from the group consisting of hydrogen, deuterium, methyl, ethyl, t-butyl, methoxy, and the following groups or any combination thereof:

[0025]

[0026]

[0027] wherein R is selected from the group consisting of hydrogen, phenyl, naphthyl, biphenyl, methylphenyl, ethylphenyl, and terphenyl.

[0028] Further, in the above technical solutions, the term "substituted or unsubstituted" means substituted with one, two, or more substituents selected from the group consisting of deuterium; a halogen group; a nitrile group; a hydroxyl group; a carbonyl group; an ester group; a silyl group; a boron group; a substituted or unsubstituted alkyl group; a substituted or unsubstituted cycloalkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted alkenyl group; a substituted or unsubstituted alkyl amine group; a substituted or unsubstituted heterocyclic amine group; a substituted or unsubstituted aryl amine group; a substituted or unsubstituted aryl group; and a substituted or unsubstituted heterocyclic group, or substituted with a substituent in which two or more of the above substituents are connected, or without a substituent. For example, the "substituent in which two or more of the above substituents are connected" can include a biphenyl group. In other words, the biphenyl group can be an aryl group, or can be interpreted as a substituent in which two phenyl groups are connected.

[0029] Preferably, the nitrogen-containing heterocyclic compound is selected from any one of the following structures, but is not limited thereto:

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] The above only lists some specific structural formulas, but the series of nitrogen-containing heterocyclic compounds claimed by the present application are not limited to the above molecular structures, and other specific molecular structures can be obtained by simple transformation of the groups disclosed in the present application and their substitution positions, which will not be described one by one here, and all of them should fall within the protection scope of the present application.

[0036] The preparation method of the above-mentioned nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus specifically includes the following steps:

[0037] Under N2 protection, the reactants A-1 (1.0 eq), reactants B-1 (1-1.2 eq), tetrakis(triphenylphosphine)palladium (0.01-0.02 eq) and potassium carbonate (2.1-2.3 eq) are added to a mixed solvent of toluene, ethanol and water (2-4:1:1), respectively, and the temperature is raised to 100-120°C, and the reaction is carried out for 8-12 h. After the reaction is completed, the temperature is cooled to room temperature, and after the solid is completely precipitated, it is filtered under suction, washed with water to remove the salt, then washed with a small amount of ethanol, the filter cake is dried, recrystallized in 1,4-dioxane, and the compound represented by general formula I is obtained.

[0038] The specific reaction principle is as follows:

[0039]

[0040] The above-mentioned nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus is used for preparing an organic electroluminescent device.

[0041] Preferably, the organic electroluminescent device comprises a first electrode, an organic layer, and a second electrode; wherein the organic layer comprises the above-mentioned nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus.

[0042] Preferably, the organic layer comprises one or more of a hole injection layer, a hole transport layer, a layer with both hole injection and hole transport skills, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a layer with both electron transport and electron injection skills, and at least one layer comprises the nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus.

[0043] Preferably, according to one embodiment of the present application, the above-mentioned organic layer comprises an electron transport layer, and the electron transport layer comprises the nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus.

[0044] The nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus prepared by the present application can exist in the organic layer in a single form or mixed with other substances; in the case where the above-mentioned organic light emitting element comprises multiple organic layers, the above-mentioned organic layers can be formed by the same substance or different substances.

[0045] Preferably, the organic layer includes a light-emitting layer, and the light-emitting layer includes a host material and the nitrogen-containing heterocyclic compound having o-phenanthroline as a mother nucleus.

[0046] Preferably, the mass ratio of the host material to the nitrogen-containing heterocyclic compound having o-phenanthroline as a mother nucleus is 90:10 to 99.5:0.5.

[0047] Preferably, in the manufacturing of the organic light-emitting element, the organic layer can be formed by a vacuum evaporation method or a solution coating method. The solution coating method includes, but is not limited to, a spin coating method, a dip coating method, a blade coating method, an inkjet printing method, a screen printing method, a spray method, and a roll coating method.

[0048] Preferably, the organic light-emitting element of the present application can be a top emission type, a bottom emission type, or a bidirectional emission type, depending on the materials used.

[0049] The device of the present application can be used in an organic light-emitting device, an organic solar cell, electronic paper, an organic photoreceptor, or an organic thin film transistor.

[0050] According to the technical solutions described above, the present application has the following advantages compared with the prior art

[0051] (1) The nitrogen-containing heterocyclic compound having o-phenanthroline as a mother nucleus provided by the present application uses functional groups with strong electron-withdrawing ability of pyridine, diazine, and triazine, effectively improving the electron mobility of the electron transport material. The problem of electron-hole imbalance in the organic electroluminescent device is improved, the light-emitting efficiency is improved, and the organic electroluminescent device prepared by using the compound has the performance advantages of low driving voltage, high efficiency, and long service life.

[0052] (2) The compound of the present application introduces a planar heteroaryl structure containing a heteroatom, further improves the electron mobility of the electron transport material, and the planar molecular structure can ensure that the π-conjugated system of the core structure is not continued, ensuring a high triplet energy level (ET), a wide band gap, further improving the light-emitting efficiency, and improving the degree of matching of the energy levels of each layer of the device, reducing the driving voltage, and prolonging the service life of the device. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creating any inventive labor.

[0054] Figure 1 NMR hydrogen spectrum of the compound 3 in Example 1 of the present application;

[0055] Figure 2 NMR of hydrogen spectrum of compound 11 of Example 2 of the present application;

[0056] Figure 3 NMR of hydrogen spectrum of compound 93 of Example 3 of the present application. DETAILED DESCRIPTION

[0057] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0058] Example 1

[0059] The compound 3 was prepared, and the specific steps were as follows:

[0060] The reactant A-3 (30 mmol), the reactant B-3 (36 mmol), tetrakis(triphenylphosphine)palladium (0.3 mmol) and potassium carbonate (66 mmol) were added into a mixed solvent of toluene, ethanol and water (300 mL: 100 mL: 100 mL) under the protection of N2, and the temperature was raised to 110°C, and the reaction was carried out for 8 h. After the reaction was completed, the temperature was cooled to room temperature, and after the solid was completely precipitated, the filter cake was washed with water to remove the salt, then washed with a small amount of ethanol, dried, and then recrystallized in 1,4-dioxane to obtain the compound 3 (19.0 g, yield: 84%);

[0061] HPLC purity: >99.7%.

[0062] Mass spectrometry test: the theoretical value was 754.85, and the test value was 755.18.

[0063] Elemental analysis:

[0064] Theoretical value: C, 82.74; H, 4.01; N, 11.13; O, 2.12

[0065] Test value: C, 82.47; H, 4.28; N, 11.18; O, 2.22

[0066] NMR of hydrogen spectrum: as shown in Figure 1

[0067] The specific reaction principle was as follows:

[0068]

[0069] Example 2

[0070] ​The compound 11 was prepared according to the following specific steps:

[0071] The reactant A-11 (30 mmol), the reactant B-11 (33 mmol), tetrakis(triphenylphosphine)palladium (0.45 mmol) and potassium carbonate (63 mmol) were added into a mixed solvent of toluene, ethanol and water (300 mL: 100 mL: 100 mL) respectively under the protection of N2, and the reaction was carried out at 110°C for 8 h. After the reaction was completed, the reaction system was cooled to room temperature. After the solid was completely precipitated, the salt was removed by filtration, and then the filter cake was washed with water and a small amount of ethanol, and then dried. The dried filter cake was recrystallized in 1,4-dioxane to obtain the compound 11 (16.9 g, yield: 88%);

[0072] HPLC purity: > 99.6%.

[0073] Mass spectrometry test: the theoretical value was 639.76, and the test value was 639.88.

[0074] Elemental analysis:

[0075] Theoretical value: C, 84.48; H, 4.57; N, 10.95

[0076] Test value: C, 84.39; H, 4.71; N, 10.98

[0077] Nuclear magnetic resonance hydrogen spectrum: as shown in Figure 2

[0078] The specific reaction principle is as follows:

[0079]

[0080] Example 3

[0081] The compound 93 was prepared according to the following specific steps:

[0082] The reactant A-93 (30 mmol), the reactant B-93 (36 mmol), tetrakis(triphenylphosphine)palladium (0.03 mmol) and potassium carbonate (63 mmol) were added into a mixed solvent of toluene, ethanol and water (400 mL: 100 mL: 100 mL) respectively under the protection of N2, and the reaction was carried out at 105°C for 10 h. After the reaction was completed, the reaction system was cooled to room temperature. After the solid was completely precipitated, the salt was removed by filtration, and then the filter cake was washed with water and a small amount of ethanol, and then dried. The dried filter cake was recrystallized in 1,4-dioxane to obtain the compound 93 (18.0 g, yield: 85%);

[0083] HPLC purity: > 99.7%.

[0084] Mass spectrometry test: the theoretical value was 704.84, and the test value was 705.04.​

[0085] Elemental analysis:

[0086] Theoretical value: C, 83.50; H, 4.58; N, 11.92

[0087] Test value: C, 83.36; H, 4.70; N, 12.00

[0088] NMR hydrogen spectrum: as shown in Figure 3 ;

[0089] The specific reaction principle is as follows:

[0090]

[0091] Examples 4-59

[0092] The preparation of compounds 1, 2, 4, 6, 7, 8, 9, 12, 13, 14, 16, 18, 19, 20, 22, 24, 25, 26, 27, 29, 30, 32, 33, 34, 35, 40, 45, 47, 50, 53, 54, 55, 60, 62, 64, 67, 69, 71, 72, 77, 78, 80, 81, 82, 85, 86, 88, 89, 90, 94, 97, 104, 105, 110, 113, 114 is completed according to the synthesis method of reference examples 1-3.

[0093] The molecular formula, mass spectrum and yield are shown in Table 1.

[0094] Table 1 Molecular formula, mass spectrum and yield of compounds

[0095]

[0096]

[0097]

[0098] In addition, it should be noted that other compounds of the present application can be obtained by referring to the synthesis method of the above-mentioned examples, so they are not listed one by one here.

[0099] In addition, in order to further illustrate the application effect of the nitrogen-containing heterocyclic compound with o-phenanthroline as the mother nucleus prepared by the present application in the electroluminescent device, the inventors also carried out the following test experiments, as follows:

[0100] Device application example

[0101] The compound obtained by the example is used to prepare an organic electroluminescent device, and the specific process is as follows:

[0102] a. ITO anode: ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150 nm was cleaned in distilled water for 2 times, ultrasonic washing for 30 min, and then repeatedly cleaned in distilled water for 2 times, ultrasonic washing for 10 min, and then transferred to the spin dryer for spin-drying, and finally baked in a vacuum oven at 220°C for 2 hours, and then cooled to room temperature for use. The substrate was used as an anode, and a device process was performed using an evaporation machine, and other functional layers were sequentially evaporated thereon;

[0103] b. HIL (hole injection layer): HT and P-dopant were vacuum evaporated at an evaporation rate of

[0104] c. HTL (hole transport layer): HT was vacuum evaporated on the hole injection layer as a hole transport layer at an evaporation rate of

[0105] d. Light-emitting auxiliary layer: The compound of the above embodiment was vacuum evaporated on the hole transport layer as a light-emitting auxiliary layer at an evaporation rate of

[0106] e. EML (emitting layer): Then, the host material (Host) and the dopant material (Dopant) were vacuum evaporated on the light-emitting auxiliary layer as an emitting layer at an evaporation rate of

[0107] f. ETL (electron transport layer): ET and Liq were vacuum evaporated as an electron transport layer at an evaporation rate of

[0108] g. EIL (electron injection layer): Yb film layer was evaporated as an electron injection layer at an evaporation rate of

[0109] h. Cathode: Magnesium and silver were evaporated as a cathode at an evaporation rate of

[0110] i. Light extraction layer: CPL was vacuum evaporated on the cathode as a light extraction layer at an evaporation rate of

[0111] ​​​​​​​​j, the substrate after evaporation is packaged: first, the cleaned cover plate is coated with UV glue by using a coating device, then the coated cover plate is moved to the pressing section, the substrate after evaporation is placed on the upper end of the cover plate, finally the substrate and the cover plate are bonded under the action of the bonding device, and the UV glue is cured by light at the same time.

[0112] Device structure:

[0113] ITO / Ag / ITO / HT:P-dopant (10 nm, 2%) / HT (120 nm) / prime (10 nm) / Host:Dopant (25 nm, 3%) / ET:Liq (35 nm, 50%) / Yb (1 nm) / Mg:Ag (18 nm, 1:9) / CPL (70 nm).

[0114] The chemical formula of the corresponding substance is as follows:

[0115]

[0116] Application Examples 1-59

[0117] The organic electroluminescent devices of application examples 1-59 are prepared according to the preparation method of the organic electroluminescent device described above, with the difference that the compound 1 in application example 1 is replaced by other 58 compounds respectively to form a light-emitting auxiliary layer;

[0118] Comparative Examples 1-4

[0119] The organic electroluminescent devices are prepared according to the same preparation scheme of application example 1, wherein compound 1 is replaced by comparative compounds 1-4 respectively; wherein the structural formulas of comparative compounds 1-4 are as follows:

[0120]

[0121]

[0122] The obtained application examples 1-59 and comparative examples 1-4 devices are tested for light-emitting properties under 1000 (nits) brightness, and the driving voltage, luminous efficiency, BI value and lifetime of the organic electroluminescent device are characterized, and the test results are as follows table 2:

[0123] Table 2 Performance test results of electroluminescent devices of application examples 1-59 and comparative examples 1-4

[0124]

[0125]

[0126]

[0127] As can be seen from Table 2, the organic electroluminescent devices according to Examples 1 to 59 prepared using the electron transport material according to the present application have improved driving voltage, luminous efficiency, BI and lifespan compared to the conventional organic electroluminescent devices according to Comparative Examples 1 to 4.

[0128] The foregoing description of the disclosed embodiments enables a person skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nitrogen-containing heterocyclic compound having o-phenanthroline as a parent nucleus, characterized by comprising: The structural formula of the nitrogen-containing heterocyclic compound is as follows:

2. Use of a nitrogen-containing heterocyclic compound having o-phenanthroline as a parent nucleus in the production of an organic electroluminescent device, characterized by The electron transport material in the organic electroluminescent device comprises the nitrogen-containing heterocyclic compound with o-phenanthroline as a mother nucleus according to claim 1.

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