An organic electroluminescence compound, a preparation method therefor, and use thereof

Abstract

The application discloses an organic electroluminescent compound, a preparation method and application thereof, and relates to the technical field of luminescent materials. Through a novel heterocyclic organic electroluminescent compound containing a nitrogen atom, the symmetry of the molecule is destroyed by the nitrogen-containing heterocycle to avoid the aggregation of molecules; the electron-withdrawing functional group groups such as diazine and triazine are adopted to effectively improve the electron mobility of the electron transport material, improve the problem of electron-hole imbalance in the organic electroluminescent device, and improve the luminous efficiency. The organic electroluminescent compound has good electron mobility, and meanwhile, the planar molecular structure can also make the pi-conjugated system of the core structure not be continued, so that the high triplet energy level (ET) and the wide band gap are ensured, which is beneficial to further improve the luminous efficiency and improve the degree of matching of the energy levels of the layers of the device. The organic electroluminescent device prepared by using the organic electroluminescent compound 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 light-emitting materials, in particular to an organic electroluminescent compound, a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of information technology, people have put forward new goals and requirements for the performance of information display systems, and the display has high brightness, high resolution, wide viewing angle and low energy consumption, which has become a research hotspot. Organic electroluminescence (OLED) display technology can meet the above needs of people, and has other advantages such as wide working temperature and flexible display. Therefore, after CRT (cathode ray tube) display, LCD (liquid crystal display), PDP (plasma display) flat panel display, organic electroluminescence (OLED) display technology has become a new generation of flat panel display research hotspot.

[0003] An organic electroluminescent element is a self-light-emitting element that utilizes the following principle: by applying an electric field, a fluorescent substance is made to emit light using the recombination energy of holes injected from an anode and electrons injected from a cathode. It has the following structure: an anode, a cathode, and an organic material layer interposed therebetween. In order to improve the efficiency and stability of the organic electroluminescent element, the organic material layer usually includes multiple layers having different materials, such as a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer, an electron transport layer (ETL), and an electron injection layer (EIL). In such an organic light-emitting element, when a voltage is applied between the anode and the cathode, holes from the anode and electrons from the cathode are injected into the organic material layer, and the resulting excitons generate light having a specific wavelength when they migrate to the ground state.

[0004] The electron transport layer (ETL) of OLED has two main functions: on the one hand, it forms a small potential barrier with the cathode interface, and on the other hand, it can block holes. Therefore, the selection of electron transport materials should meet the following points: high electron mobility, high electron affinity, good film-forming property, and high thermal stability. Flat aromatic compounds with large π-bond conjugated structure are usually used to synthesize electron transport materials. Such materials have good electron acceptor properties and can effectively transfer electrons under the action of an electric field. Due to electron capture, there are not many known electron transport materials with good performance. From the perspective of element electronegativity, fluorine, oxygen, nitrogen, sulfur and other elements are more likely to accept electrons, and most of the multi-substituted compounds and heterocyclic compounds of such elements have electron transport properties. In addition, since positively charged metal ions are easy to accept electrons, most organometallic complexes also have good electron transport properties.

[0005] Therefore, the currently commonly used electron transport materials mainly include metal complexes (such as Alq3), oxadiazole compounds (such as PBD) and nitrogen-containing five-membered heterocyclic compounds (such as TPBI). As a key component in the OLED structure, the electron transport layer also has a great influence on the service life of the device. For example, the mobility and energy band structure of the material determine the local electric field, carrier and Joule heat distribution in the electron transport layer and its vicinity, thereby directly affecting the aging speed of the organic material and the device.

[0006] Therefore, it is an urgent technical problem for those skilled in the art to develop an electron transport material with high mobility, so that the organic electroluminescent device prepared therefrom has the performance advantages of low driving voltage, high efficiency and long service life.

[0007] In view of this, the present application is proposed. SUMMARY

[0008] The present application aims to provide an organic electroluminescent compound and a preparation method thereof, and to provide a novel luminescent compound, thereby imparting the luminescent device with low driving voltage, high luminescent efficiency and long service life.

[0009] Another object of the present application is to provide an organic electroluminescent device with low driving voltage, high luminescent efficiency and long service life.

[0010] A third object of the present application is to provide the use of the organic electroluminescent device in the preparation of an organic light-emitting device, an organic solar cell, electronic paper, an organic photoreceptor or an organic thin-film transistor.

[0011] The present application is achieved as follows:

[0012] The present application provides an organic electroluminescent compound, the structure of which is as follows:

[0013]

[0014] wherein n is an integer from 1 to 4;

[0015] X1-X3 are each independently selected from any one of C and N, and at least one of X1-X3 is N;

[0016] L is selected from any one of a bond, a substituted or unsubstituted C6-C30 arylene group and a substituted or unsubstituted C6-C30 heteroarylene group, and the heteroatom in the heteroarylene group is selected from at least one of oxygen, nitrogen and sulfur;

[0017] Ar1and Ar2are each independently selected from any one of a substituted or unsubstituted C6-C30aryl, a substituted or unsubstituted 3- to 30-membered heteroaryl, and a substituted or unsubstituted 3- to 30-membered heterocycloalkyl, and the heteroatom in the heteroaryl and heterocycloalkyl is each independently selected from at least one of oxygen, nitrogen, and sulfur;

[0018] R1, R2, R3, R4, and R5are each independently selected from any one of hydrogen, deuterium, halogen, cyano, carboxyl, nitro, hydroxyl, amino, alkylsilyl, a substituted or unsubstituted C1-C30alkyl, a substituted or unsubstituted C2-C30alkenyl, a substituted or unsubstituted C2-C30alkynyl, a substituted or unsubstituted C3-C30cycloalkyl, a substituted or unsubstituted 3- to 30-membered heterocycloalkyl, a substituted or unsubstituted C6-C30aryl, a substituted or unsubstituted 3- to 20-membered heteroaryl, and a substituted or unsubstituted 3- to 25-membered heteroarylamino, and the heteroatom in the heterocycloalkyl, heteroaryl, and heteroarylamino is each independently selected from at least one of oxygen, nitrogen, and sulfur.

[0019] The present application also provides a preparation method of the organic electroluminescent compound, and a synthetic route is as follows:

[0020]

[0021] Hal1, Hal2, and Hal3are each independently selected from any one of fluorine, chlorine, bromine, and iodine.

[0022] The present application also provides an organic electroluminescent device including an organic material layer containing the above-mentioned organic electroluminescent compound.

[0023] The present application also provides an application of the above-mentioned organic electroluminescent device in preparing an organic light-emitting device or an organic thin-film transistor.

[0024] The present application has the following beneficial effects: by using a novel nitrogen atom-containing heterocyclic organic electroluminescent compound, the symmetry of the molecule is destroyed by the nitrogen-containing heterocycle, the intermolecular aggregation is avoided, and the characteristics such as difficult crystallization, difficult aggregation, and good film-forming property are achieved. The electron-transporting material has high electron mobility, the problem of electron-hole imbalance in the organic electroluminescent device is improved, and the light-emitting efficiency is improved. The organic electroluminescent compound provided by the present application has good electron mobility, and the planar molecular structure also ensures that the π-conjugated system of the core structure is not continued, guarantees a high triplet energy level (ET) and a wide band gap, and is conducive to further improving the light-emitting efficiency and improving the degree of matching of the energy levels of the layers of the device.

[0025] Therefore, the organic electroluminescent device prepared by using the organic electroluminescent compound provided by the application has the performance advantages of low driving voltage, high efficiency and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0027] Figure 1 The nuclear magnetic resonance hydrogen spectrum of the compound prepared for the present embodiment 1 is shown in the following figure:

[0028] Figure 2 The nuclear magnetic resonance hydrogen spectrum of the compound prepared for the present embodiment 2 is shown in the following figure. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the application more clear, the technical solutions in the embodiments of the application will be described clearly and completely below. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.

[0030] In the terms of the present application, "substitution" means that the hydrogen atoms bonded to the carbon atoms of the compound are changed into another substituent, and the position of substitution is not limited as long as it is the position of hydrogen atoms being substituted (i.e. the position that can be substituted by the substituent), and when two or more substituents are substituted, the two or more substituents can be the same as or different from each other.

[0031] In the present specification, the term "substituted or unsubstituted" means being substituted with one, two or more substituents selected from the following. For example, "a substituent in which two or more substituents are connected" can include biphenyl. In other words, biphenyl can be an aryl group, or can be interpreted as a substituent in which two phenyl groups are connected.

[0032] The present application provides an organic electroluminescent compound, and a structure formula of the organic electroluminescent compound is shown in the following general formula 1:

[0033]

[0034] In the present application, n is an integer of 1-4, which can be 1, 2, 3 or 4, and n is preferably 1.

[0035] X1-X3are each independently selected from any one of C and N, and at least one of X1-X3is N. That is, X1-X3cannot all be C, and there must be 1, 2, or 3 Ns. By using a functional group group with strong electron-withdrawing ability such as diazine, triazine, etc., the electron mobility of the electron transport material can be effectively improved.

[0036] L is selected from any one of a bond, a substituted or unsubstituted C6-C30arylene, and a substituted or unsubstituted C6-C30heteroarylene, and the heteroatom in the heteroarylene is selected from at least one of oxygen, nitrogen, and sulfur. Specifically, C6-C30 refers to the number of C atoms in the group, which can be any integer from 6 to 30, such as C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C26, C27, C28, C29, C30.

[0037] Ar1and Ar2are each independently selected from any one of a substituted or unsubstituted C6-C30aryl, a substituted or unsubstituted 3- to 30-membered heteroaryl, and a substituted or unsubstituted 3- to 30-membered heterocycloalkyl, and the heteroatom in the heteroaryl and the heterocycloalkyl is each independently selected from at least one of oxygen, nitrogen, and sulfur. Ar1and Ar2may be the same or different, and are each independently selected from the above groups.

[0038] R1, R2, R3, R4, and R5are each independently selected from any one of hydrogen, deuterium, halogen, cyano, carboxyl, nitro, hydroxyl, amino, alkylsilyl, a substituted or unsubstituted C1-C30alkyl, a substituted or unsubstituted C2-C30alkenyl, a substituted or unsubstituted C2-C30alkynyl, a substituted or unsubstituted C3-C30cycloalkyl, a substituted or unsubstituted 3- to 30-membered heterocycloalkyl, a substituted or unsubstituted C6-C30aryl, a substituted or unsubstituted 3- to 20-membered heteroaryl, and a substituted or unsubstituted 3- to 25-membered heteroarylamino, and the heteroatom in the heterocycloalkyl, the heteroaryl, and the heteroarylamino is each independently selected from at least one of oxygen, nitrogen, and sulfur. R1, R2, R3, R4, and R5may be the same or different, and are each independently selected from the above groups; and the heteroatom in the heterocycloalkyl, the heteroaryl, and the heteroarylamino may be the same or different.

[0039] It can be understood that the position of L in Formula 1 can be any substitution position, including the following general formula:

[0040]

[0041] To further improve the electron mobility of the electron transport material formed by the compound, the inventors optimized the selection of L, Ar1, Ar2, R1, R2, R3, R4 and R5 in the general formula:

[0042] In preferred embodiments, L is selected from any one of a bond, phenyl, tolyl, naphthyl, anthryl, fluorenyl, phenanthryl, biphenyl, p-terphenyl, m-terphenyl, phenylnaphthyl, deuterated phenyl, pyridyl, quinolyl and oxazolyl.

[0043] In preferred embodiments, R1, R2, R3, R4 and R5 are each independently selected from any one of hydrogen, deuterium, halogen, cyano, carboxyl, nitro, hydroxyl, amino, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted 3-10 membered heterocycloalkyl, substituted or unsubstituted C6-C18 aryl and substituted or unsubstituted 3-10 membered heteroaryl.

[0044] In preferred embodiments, Ar1 and Ar2 are each independently selected from any one of the following structures:

[0045]

[0046] The inventors found that the organic electroluminescent compound is the following compound, and the prepared organic electroluminescent device has the performance advantages of low driving voltage, high efficiency and long service life. The structures of specific compounds are shown as compounds 1-216:

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] The organic electroluminescent compound of the embodiment of the present application can be prepared by a synthetic method known to those skilled in the art. For example, the following reaction scheme is preferably used for preparation. The embodiment of the present application provides a method for preparing an organic electroluminescent compound, and the synthetic route is as follows:

[0058]

[0059] Hal1, Hal2, and Hal3 are each independently selected from any one of fluorine, chlorine, bromine, and iodine.

[0060] The preparation method specifically comprises the following steps:

[0061] (1) Preparation of intermediate 1: Dissolve raw material B in THF (tetrahydrofuran), then replace the gas 3 times, cool to 0°C, slowly add NaH, react for 2h, add raw material A under nitrogen protection, slowly warm to 25°C, stir for 12h, to prepare intermediate 1;

[0062] (2) Preparation of intermediate 2: Dissolve intermediate 1 in THF solution, slowly add NaH, react for 2h, cool to 0°C, add MeI (methyl iodide) under nitrogen protection, warm to 50°C, react for 6h, to prepare intermediate 2;

[0063] (3) Preparation of intermediate 3: Dissolve intermediate 2 in THF, then replace the gas 3 times, cool to -78°C, slowly add n-BuLi (n-butyllithium), react for 4h, add raw material C under nitrogen protection, slowly warm to 25°C, stir for 12h, to prepare intermediate 3;

[0064] (4) Preparation of intermediate 4: Dissolve intermediate 3 in dichloromethane solution, stir uniformly, cool to 0°C, drop TFA, react for 8h, to prepare intermediate 4;

[0065] (5) Preparation of intermediate 5: Dissolve intermediate 4 in dichloromethane solution, drop TFA, stir uniformly, react at room temperature for 8h, to prepare intermediate 5;

[0066] (6) Preparation of intermediate 6: Dissolve intermediate 5 in carbon tetrachloride solution, add BPO (benzoyl peroxide), slowly add NBS (N-bromosuccinimide), stir uniformly, slowly warm to 80°C, react for 10h, to prepare intermediate 6;

[0067] (7) Preparation of general formula 1: Dissolve intermediate 6 and raw material D in toluene, ethanol, and water solution under nitrogen protection, add cesium carbonate, phosphine ligand, and palladium catalyst, stir uniformly, warm to 90°C, and reflux for 6h, to prepare general formula 1.

[0068] The preparation method has the following route:

[0069]

[0070] The present application also provides an organic electroluminescent device comprising an organic material layer, wherein the organic material layer comprises the organic electroluminescent compound provided in the present application. The organic electroluminescent compound provided in the present application can significantly improve the electron mobility of the electron transport material, and the organic electroluminescent device prepared therefrom has the advantages of low driving voltage, high efficiency, and long service life.

[0071] In some embodiments, the organic electroluminescent device further comprises a first electrode and a second electrode, and the organic material layer is located between the first electrode and the second electrode; the organic material layer comprises an electron transport layer, and the electron transport layer comprises the organic electroluminescent compound. The organic electroluminescent compound is preferably used as the electron transport layer, and can also be introduced into other layers, which is not limited herein.

[0072] The organic electroluminescent device provided in the present application can be applied in the preparation of an organic light-emitting device or an organic thin-film transistor, and has a wide application prospect.

[0073] The features and properties of the present application are further described in detail below in combination with embodiments.

[0074] Embodiment 1

[0075] The present embodiment provides a preparation method of an organic electroluminescent compound, and the synthetic route and specific steps are as follows:

[0076]

[0077] The raw material B (44.00 mmol) was dissolved in THF, followed by air exchange for 3 times, cooling to 0°C, slowly adding NaH (44.00 mmol), reacting for 2 h, adding the raw material A (40.00 mmol) under nitrogen protection, slowly warming to 25°C, reacting for 12 h, then slowly adding distilled water to the reaction solution to quench the reaction, and extracting the reaction solution with DCM; then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator; the remaining material was purified by column chromatography using a mixed solution of DCM and PE (1:10) to obtain the intermediate 1 (12.84 g, yield 76.35%).

[0078] Intermediate 1 (30.51 mmol) was dissolved in THF solution, NaH (67.17 mmol) was added slowly, the reaction was carried out for 2 h, cooled to 0 °C, Mel (67.17 mmol) was added under nitrogen protection, the temperature was raised to 50 °C, the reaction was carried out for 6 h, then distilled water was slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM; then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator; the remaining material was purified by column chromatography with a mixed solution of DCM and PE (1 :6) to obtain intermediate 2 (10.57 g, yield 77.21%).

[0079] Intermediate 2 (23.55 mmol) was dissolved in THF, then aerated 3 times, cooled to -78 °C, n-BuLi (28.26 mmol) was added slowly, the reaction was carried out for 4 h, the raw material C (23.55 mmol) was added under nitrogen protection, the temperature was slowly raised to 25 °C, stirred for 12 h, then distilled water was slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM; then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator; the remaining material was purified by column chromatography with a mixed solution of DCM and PE (1 :4) to obtain intermediate 3 (8.96 g, yield 68.97%).

[0080] Intermediate 3 (16.22 mmol) was dissolved in dichloromethane solution, stirred uniformly, cooled to 0 °C, boron trifluoride ether (16.22 mmol) was added dropwise, the reaction was carried out for 8 h, after the reaction was completed, ethanol was added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM; then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator; the remaining material was purified by column chromatography with a mixed solution of DCM and PE (1 :20) to obtain intermediate 4 (6.65 g, yield 76.81%).

[0081] Intermediate 4 (12.45 mmol) was dissolved in dichloromethane solution, trifluoroacetic acid (20 mL) was added dropwise, stirred uniformly, the reaction was carried out for 8 h at room temperature, the reaction was completed using a rotary evaporator to remove the solvent; the remaining material was purified by column chromatography with a mixed solution of DCM and PE (1 :12) to obtain intermediate 5 (4.46 g, yield 82.66%).

[0082] Intermediate 5 (10.27 mmol) was dissolved in carbon tetrachloride solution, BPO (1.02 mmol) was added, NBS (20.54 mmol) was slowly added, stirred uniformly, slowly warmed to 80°C, reacted for 10h, after the reaction was completed, the reaction liquid was cooled to room temperature, and the solvent was removed using a rotary evaporator, the remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:4) to obtain intermediate 6 (3.60g, yield 81.45%).

[0083] Intermediate 6 (8.33 mmol) and raw material D (8.33 mmol) were dissolved in a solution of toluene, ethanol and water under nitrogen protection, cesium carbonate (16.66 mmol), X-Phos (0.41 mmol), palladium acetate (0.41 mmol) were added, stirred uniformly, warmed to 90°C and refluxed for 6h; after the reaction was completed, the temperature was slightly lowered, filtered using diatomite to remove salt and catalyst, the filtrate was cooled to room temperature, washed with water three times, the organic phase was retained, then the aqueous phase was extracted with ethyl acetate; after the organic phases were combined, anhydrous magnesium sulfate was used for drying, and the solvent was removed using a rotary evaporator; the remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 2:1) to obtain compound 1 (4.16g, yield 79.57%, MW:628.78), the nuclear magnetic resonance hydrogen spectrum is shown in Figure 1 .

[0084] The obtained compound-1 was detected and analyzed, and the results were as follows:

[0085] HPLC purity: >99.6%.

[0086] Mass spectrometry test: the theoretical value was 628.78; the test value was 628.97.

[0087] Elemental analysis:

[0088] The calculated value was: C, 85.96; H, 5.13; N, 8.91.

[0089] The test value was: C, 85.75; H, 5.33; N, 9.14.

[0090] Example 2

[0091] The embodiment provides a preparation method of an organic electroluminescent compound, the synthesis route and specific steps are as follows:

[0092]

[0093] The raw material B (44.00 mmol) was dissolved in THF, then aerated 3 times, cooled to 0°C, and NaH (44.00 mmol) was slowly added. The reaction was carried out for 2 h, then raw material A (40.00 mmol) was added under nitrogen protection, and the temperature was slowly raised to 25°C. The reaction was carried out for 12 h, then distilled water was slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. Then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography with a mixed solution of DCM and PE (1:10) to obtain intermediate 1 (13.50 g, yield 80.28%).

[0094] The intermediate 1 (32.08 mmol) was dissolved in THF solution, and NaH (70.57 mmol) was slowly added. The reaction was carried out for 2 h, then the temperature was lowered to 0°C, and Mel (70.57 mmol) was added under nitrogen protection. The temperature was raised to 50°C, and the reaction was carried out for 6 h. Then distilled water was slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. Then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography with a mixed solution of DCM and PE (1:6) to obtain intermediate 2 (10.72 g, yield 74.56%).

[0095] The intermediate 2 (23.88 mmol) was dissolved in THF, then aerated 3 times, cooled to -78°C, and n-BuLi (28.65 mmol) was slowly added. The reaction was carried out for 4 h, then raw material C (23.88 mmol) was added under nitrogen protection, and the temperature was slowly raised to 25°C. The reaction was carried out for 12 h, then distilled water was slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. Then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography with a mixed solution of DCM and PE (1:4) to obtain intermediate 3 (9.92 g, yield 75.32%).

[0096] The intermediate 3 (17.96 mmol) was dissolved in dichloromethane solution, stirred uniformly, cooled to 0°C, and boron trifluoride ether (17.96 mmol) was added dropwise. The reaction was carried out for 8 h, then ethanol was added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. Then the extracted organic layer was dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography with a mixed solution of DCM and PE (1:20) to obtain intermediate 4 (7.33, yield 76.48%).

[0097] Intermediate 4 (13.72 mmol) was dissolved in dichloromethane solution, trifluoroacetic acid (20 mL) was added dropwise, stirred uniformly, reacted at room temperature for 8 h, and the solvent was removed using a rotary evaporator after the reaction was completed; the remaining material was purified by column chromatography using a mixed solution of DCM and PE (1:12) to obtain intermediate 5 (4.50 g, yield 75.69%).

[0098] Intermediate 5 (10.36 mmol) was dissolved in carbon tetrachloride solution, BPO (1.03 mmol) was added, NBS (20.72 mmol) was slowly added, stirred uniformly, slowly warmed to 80°C, reacted for 10 h, and after the reaction was completed, the temperature was lowered to room temperature, and the reaction liquid was removed using a rotary evaporator, and the remaining material was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:4) to obtain intermediate 6 (3.63 g, yield 81.25%).

[0099] Under nitrogen protection, intermediate 6 (8.40 mmol) and raw material D (8.40 mmol) were dissolved in toluene, ethanol and water solution, cesium carbonate (16.80 mmol), X-Phos (0.42 mmol), palladium acetate (0.42 mmol) were added, stirred uniformly, warmed to 90°C, and refluxed for 6 h; after the reaction was completed, the temperature was lowered slightly, filtered using diatomite to remove salt and catalyst, and after the filtrate was cooled to room temperature, it was washed with water three times, the organic phase was retained, and then the aqueous phase was extracted with ethyl acetate; after the organic phases were combined, anhydrous magnesium sulfate was used for drying, and the solvent was removed using a rotary evaporator; the remaining material was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 2:1) to obtain compound 16 (4.77 g, yield 79.24%, MW: 718.86), and the nuclear magnetic resonance hydrogen spectrum is shown in Figure 2 .

[0100] The obtained compound-16 was detected and analyzed, and the results were as follows:

[0101] HPLC purity: >99.6%.

[0102] Mass spectrometry test: the theoretical value was 718.86; the test value was 718.57.

[0103] Elemental analysis:

[0104] The calculated value was: C, 85.21; H, 4.77; N, 7.79.

[0105] The test value was: C, 84.97; H, 4.98; N, 7.92.

[0106] Example 3

[0107] The embodiment provides a preparation method of an organic electroluminescent compound, a synthetic route and specific steps are as follows:

[0108]

[0109] The raw material B (44.00 mmol) is dissolved in THF, then aerated for 3 times, cooled to 0 DEG C, slowly added with NaH (44.00 mmol), reacts for 2h, under the protection of nitrogen, added with the raw material A (40.00 mmol), slowly heated to 25 DEG C, reacts for 12h, then distilled water is slowly added into the reaction solution to quench the reaction, and the reaction solution is extracted with DCM; then the extracted organic layer is dried with magnesium sulfate, and the solvent is removed by using a rotary evaporator; the remaining material is purified by column chromatography with a mixed solution of DCM and PE (1:10) to obtain the intermediate 1 (13.20g, yield 78.52%).

[0110] The intermediate 1 (31.37 mmol) is dissolved in THF solution, slowly added with NaH (69.01 mmol), reacts for 2h, cooled to 0 DEG C, under the protection of nitrogen, added with MeI (69.01 mmol), heated to 50 DEG C, reacts for 6h, then distilled water is slowly added into the reaction solution to quench the reaction, and the reaction solution is extracted with DCM; then the extracted organic layer is dried with magnesium sulfate, and the solvent is removed by using a rotary evaporator; the remaining material is purified by column chromatography with a mixed solution of DCM and PE (1:6) to obtain the intermediate 2 (10.64g, yield 75.64%).

[0111] The intermediate 2 (23.70 mmol) is dissolved in THF, then aerated for 3 times, cooled to-78 DEG C, slowly added with n-BuLi (28.44 mmol), reacts for 4h, under the protection of nitrogen, added with the raw material C (23.70 mmol), slowly heated to 25 DEG C, stirs for 12h, then distilled water is slowly added into the reaction solution to quench the reaction, and the reaction solution is extracted with DCM; then the extracted organic layer is dried with magnesium sulfate, and the solvent is removed by using a rotary evaporator; the remaining material is purified by column chromatography with a mixed solution of DCM and PE (1:4) to obtain the intermediate 3 (10.13g, yield 77.48%).

[0112] Intermediate 3 (18.34 mmol) was dissolved in dichloromethane solution, stirred uniformly, and trifluoroboron ethyl ether (18.34 mmol) was added dropwise at 0°C. The reaction was carried out for 8 h. After the reaction was completed, ethanol was added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. Then, the extracted organic layer was dried using magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of DCM and PE (1:20) to obtain intermediate 4 (7.11 g, yield 72.67%).

[0113] Intermediate 4 (13.31 mmol) was dissolved in dichloromethane solution, and trifluoroacetic acid (20 mL) was added dropwise. The reaction was carried out uniformly at room temperature for 8 h. After the reaction was completed, the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of DCM and PE (1:12) to obtain intermediate 5 (4.71 g, yield 81.65%).

[0114] Intermediate 5 (10.85 mmol) was dissolved in carbon tetrachloride solution, and BPO (1.08 mmol) was added. NBS (21.70 mmol) was slowly added, and the reaction was carried out uniformly at 80°C for 10 h. After the reaction was completed, the reaction solution was cooled to room temperature, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:4) to obtain intermediate 6 (3.96 g, yield 84.66%).

[0115] Under nitrogen protection, intermediate 6 (9.16 mmol) and raw material D (9.16 mmol) were dissolved in a solution of toluene, ethanol, and water. Cesium carbonate (18.32 mmol), X-Phos (0.45 mmol), and palladium acetate (0.45 mmol) were added, and the reaction was carried out uniformly at 90°C for 6 h. After the reaction was completed, the temperature was slightly lowered, and diatomite was used for filtration to remove the salt and catalyst. After the filtrate was cooled to room temperature, it was washed with water three times, and the organic phase was retained. Then, the aqueous phase was extracted with ethyl acetate. After the organic phases were combined, anhydrous magnesium sulfate was used for drying, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=2:1) to obtain compound 100 (5.24 g, yield 78.64%, MW:728.90).

[0116] The obtained compound-100 was subjected to detection analysis, and the results are as follows:

[0117] HPLC purity: >99.6%.

[0118] Mass spectrometry test: the theoretical value was 728.90, and the test value was 728.75.

[0119] Elemental analysis:

[0120] The calculated values ​​are: C, 87.33; H, 4.98; N, 7.69.

[0121] The test values ​​are: C, 86.98; H, 5.21; N, 7.92.

[0122] Example 4

[0123] This embodiment provides a method for preparing an organic electroluminescent compound. The synthetic route and specific steps are as follows:

[0124]

[0125] Raw material B (44.00 mmol) was dissolved in THF, then the mixture was purged three times, cooled to 0°C, and NaH (44.00 mmol) was slowly added. The reaction was allowed to proceed for 2 h. Under nitrogen protection, raw material A (40.00 mmol) was added, the temperature was slowly raised to 25°C, and the reaction was allowed to proceed for 12 h. Distilled water was then slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. The extracted organic layer was then dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of DCM and PE (1:10) to obtain intermediate 1 (12.37 g, yield 73.57%).

[0126] Intermediate 1 (29.40 mmol) was dissolved in THF solution, and NaH (64.68 mmol) was slowly added. The reaction was carried out for 2 h, cooled to 0 °C, and MeI (64.68 mmol) was added under nitrogen protection. The temperature was then raised to 50 °C and reacted for 6 h. Distilled water was then slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. The extracted organic layer was then dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of DCM and PE (1:6) to obtain intermediate 2 (10.49 g, yield 79.54%).

[0127] Intermediate 2 (23.37 mmol) was dissolved in THF, then purged three times, cooled to -78°C, and n-BuLi (28.04 mmol) was slowly added. The reaction was allowed to proceed for 4 h. Under nitrogen protection, starting material C (23.37 mmol) was added, the temperature was slowly raised to 25°C, and the mixture was stirred for 12 h. Distilled water was then slowly added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. The extracted organic layer was then dried with magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining material was purified by column chromatography using a mixed solution of DCM and PE (1:4) to obtain intermediate 3 (9.02 g, yield 69.98%).

[0128] Intermediate 3 (16.33 mmol) was dissolved in dichloromethane solution, stirred uniformly, and trifluoroboron ether (16.33 mmol) was added dropwise at 0°C. The reaction was carried out for 8 h. After the reaction was completed, ethanol was added to the reaction solution to quench the reaction, and the reaction solution was extracted with DCM. Then, the extracted organic layer was dried using magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of DCM and PE (1:20) to obtain intermediate 4 (6.64 g, yield 76.21%).

[0129] Intermediate 4 (12.43 mmol) was dissolved in dichloromethane solution, and trifluoroacetic acid (20 mL) was added dropwise. The reaction was carried out uniformly at room temperature for 8 h. After the reaction was completed, the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of DCM and PE (1:12) to obtain intermediate 5 (4.38 g, yield 81.36%).

[0130] Intermediate 5 (10.09 mmol) was dissolved in carbon tetrachloride solution, and BPO (1.00 mmol) was added. NBS (20.18 mmol) was slowly added, stirred uniformly, and slowly warmed to 80°C. The reaction was carried out for 10 h. After the reaction was completed, the reaction solution was cooled to room temperature, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:4) to obtain intermediate 6 (3.63 g, yield 83.47%).

[0131] Under nitrogen protection, intermediate 6 (8.40 mmol) and raw material D (8.40 mmol) were dissolved in a solution of toluene, ethanol, and water. Cesium carbonate (16.80 mmol), X-Phos (0.42 mmol), and palladium acetate (0.42 mmol) were added, stirred uniformly, warmed to 90°C, and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and diatomite was used for filtration to remove the salt and catalyst. After the filtrate was cooled to room temperature, it was washed with water three times, and the organic phase was retained. Then, the aqueous phase was extracted with ethyl acetate. After the organic phases were combined, anhydrous magnesium sulfate was used for drying, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=2:1) to obtain compound 118 (4.35 g, yield 73.59%, MW: 705.87).

[0132] The obtained compound-118 was subjected to detection analysis, and the results were as follows:

[0133] HPLC purity: >99.5%.

[0134] Mass spectrometry test: the theoretical value was 705.87, and the test value was 705.66.

[0135] Elemental analysis:

[0136] The calculated values ​​are: C, 85.08; H, 5.00; N, 9.92.

[0137] The test values ​​are: C, 84.88; H, 5.28; N, 10.15.

[0138] The synthesis methods for other compounds are the same as those in the above examples, and will not be described in detail here. The mass spectra, molecular formulas, and yields of other synthetic examples are shown in Table 1 below:

[0139] Table 1 Summary of mass spectra, molecular formulas and yields of compounds

[0140]

[0141]

[0142]

[0143] Device Example 1: Fabricating an organic electroluminescent device containing compound 1, comprising the following steps:

[0144] (1) ITO anode: An ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150nm was cleaned twice with distilled water and ultrasonically washed for 30 minutes. It was then repeatedly cleaned twice with distilled water and ultrasonically washed for 10 minutes. After cleaning, it was transferred to a spin dryer for drying and finally baked in a vacuum oven at 220℃ for 2 hours. After baking, it was cooled before use. Using this substrate as the anode, a vapor deposition process was performed to deposit other functional layers sequentially on it.

[0145] (2) HIL (hole injection layer): with The evaporation rate of the hole injection layer materials HT-1 and P-dopant was determined by vacuum evaporation, and their chemical formulas are shown below. The evaporation rate ratio of HT-1 to P-dopant was 97:3, and the thickness was 10 nm.

[0146] (3) HTL (Hole Transport Layer): At a certain evaporation rate, HT-1 of 130 nm was vacuum-deposited on the hole injection layer as a hole transport layer.

[0147] (4) Light-emitting auxiliary layer: with At a certain evaporation rate, 10 nm EBL-1 was vacuum-deposited on the hole transport layer as a light-emitting auxiliary layer.

[0148] (5) EML (Emitting Layer): Then, on the above-mentioned emitting auxiliary layer, with... The host material (Host) and the dopant material (Dopant) with a thickness of 20 nm were vacuum evaporated at an evaporation rate of 1 : 1 as the light-emitting layer. The chemical formula of the Host and the Dopant is shown below. The evaporation rate ratio of the Host and the Dopant was 98:2.

[0149] (6) HBL (hole blocking layer): 5 nm of HB-1 was vacuum evaporated on the light-emitting layer as the hole blocking layer at an evaporation rate of 1 : 1.

[0150] (7) ETL (electron transport layer): 30 nm of the compound 1 provided in the above embodiment was vacuum evaporated on the hole blocking layer as the electron transport layer at an evaporation rate of 1 : 1.

[0151] (8) EIL (electron injection layer): Yb film layer 1.0 nm was evaporated at an evaporation rate of 1 : 1 to form the electron injection layer.

[0152] (9) Cathode: Magnesium and silver 18 nm were evaporated at an evaporation rate ratio of 1 : 9 to obtain the OLED device.

[0153] (10) Light extraction layer: CPL-1 with a thickness of 70 nm was vacuum evaporated on the cathode as the light extraction layer at an evaporation rate of 1 : 1. Then, the substrate on which the evaporation was completed was encapsulated. First, the cleaned cover plate was coated with UV glue by using a gluing device, and then the coated cover plate was moved to a pressing section, the substrate on which the evaporation was completed was placed on the end of the cover plate, and finally the substrate and the cover plate were attached under the action of the attaching device, and the UV glue was simultaneously cured by light irradiation.

[0154] The structural formula of the material used in each layer is shown below:

[0155]

[0156] Device Example 2-Device Example 40. Referring to the above method, the compound 1 used in Device Example 1 was replaced by compounds 16, 100, 118, 3, 7, 10, 15, 19, 22, 28, 33, 38, 44, 55, 59, 62, 67, 73, 80, 92, 97, 102, 108, 114, 120, 125, 130, 134, 136, 137, 140, 141, 143, 151, 158, 165, 169, 174, 202, respectively, as the electron transport layer, to prepare the corresponding organic electroluminescent device.

[0157] ​​​​​Device Comparative Example 1: The comparative example provides an organic electroluminescence device, the preparation method of which is only different from that of device embodiment 1 in that the organic electroluminescence device is prepared by replacing the electron transport layer (compound 1) in the above device embodiment 1 with the existing comparative compounds A, B, respectively, to prepare device comparative examples 1-4. The chemical structural formulas of comparative compounds A, B, C, and D are as follows:

[0158]

[0159] The driving voltage, luminous efficiency, BI value and lifetime of the organic electroluminescence devices obtained from the above device embodiments 1-40 and device comparative examples 1-4 were characterized at a brightness of 1000 (nits), and the test results are as shown in Table 2:

[0160] Table 2 Performance test results of organic electroluminescence devices

[0161]

[0162]

[0163]

[0164] From the above table, it can be seen that the organic electroluminescence device prepared by the organic electroluminescence compound provided by the present application as the electron transport layer has a lower starting voltage, and the luminous efficiency and lifetime are significantly improved, compared with the organic electroluminescence device prepared by compounds A, B, C, and D as the electron transport layer.

[0165] Obviously, the above embodiments are only examples for clarity and do not limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. All embodiments need not be exhaustively listed here. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

[0166] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An organic electroluminescent compound, characterized in that, Its structure is selected from any of the following structural formulas: 。 2. An organic electroluminescent device, characterized in that, It includes an organic material layer containing the organic electroluminescent compound of claim 1.

3. The organic electroluminescent device according to claim 2, characterized in that, The organic electroluminescent device further includes a first electrode and a second electrode, with the organic material layer located between the first electrode and the second electrode; the organic material layer includes an electron transport layer, and the electron transport layer contains the organic electroluminescent compound.

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