An organic electroluminescence compound and a preparation method and application thereof

Abstract

The application discloses an organic electroluminescent compound and a preparation method and application thereof, and the organic electroluminescent device prepared from the compound has the performance advantages of low driving voltage, high efficiency and long service life. Specifically, the functional group groups of diazine and triazine with strong electron-withdrawing capacity are adopted to effectively improve the electron mobility of the electron transport material. The problem of unbalance between electrons and holes in the organic electroluminescent device is improved. The light-emitting efficiency is improved. Secondly, in addition to the introduction of diazine and triazine, the planar heteroaryl structure containing heteroatoms is introduced, so that the electron mobility of the electron transport material is further improved, the pi-conjugated system of the core structure is not continued by the planar molecular structure, the high triplet energy level (ET) and the wide band gap are ensured, the light-emitting efficiency is further improved, the degree of energy level matching of each layer of the device is improved, the driving voltage is reduced, and the service life of the device is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic light-emitting materials, and more particularly to an organic electroluminescent compound and 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, low energy consumption, and 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, it has become a new favorite of the new generation of flat panel display. Organic electroluminescence display technology is also known as a flat panel display technology with dreamlike display characteristics.

[0003] An organic electroluminescent element is a self-light-emitting element using 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 of 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 of a specific wavelength when they migrate to the ground state. The structure of the electron transport material used as the electron transport layer usually contains nitrogen-containing heterocycles such as pyridine, pyrimidine, oxadiazole, triazole, and imidazole, and electron-withdrawing groups such as phosphine oxide, which have electron transport properties. As a key component in OLED structure, the electron transport layer also has a great impact on the device lifetime. For example, the mobility and energy band structure of the material determine the local electric field, charge carriers, and Joule heat distribution in the electron transport layer and its vicinity, thereby directly affecting the aging rate of the organic material and the device.

[0004] Therefore, it is an urgent technical problem for those skilled in the art to develop an organic electroluminescent compound with high mobility and an organic electroluminescent device prepared therefrom, which has the performance advantages of low driving voltage, high efficiency, and long service life. SUMMARY

[0005] Therefore, the present application provides an organic electroluminescent compound, which produces an organic electroluminescent device with low driving voltage, high luminous efficiency, and / or long service life.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An organic electroluminescent compound, the general structural formula of which is shown in Formula 1:

[0008]

[0009] Where n is an integer from 0 to 4, and n is not 0;

[0010] Z1-Z3 are each independently selected from C or N, and at least one of them is N;

[0011] L is selected from the linker, substituted or unsubstituted C6-C. 30 arylene or substituted or unsubstituted C6-C 30 The heteroaryl group, wherein the heteroatom is selected from oxygen, nitrogen, and sulfur;

[0012] Ar1 and Ar2 may be identical or different from each other, and each is independently selected from substituted or unsubstituted C6-C. 30 Aryl, substituted or unsubstituted 3- to 30-membered heteroaryl groups, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur; substituted or unsubstituted 3- to 30-membered heterocyclic alkyl groups, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur;

[0013] R1, R2, and R3 may be the same as or different from each other, and each is independently selected from hydrogen, deuterium, halogen, cyano, carboxyl, nitro, hydroxyl, amino, substituted or unsubstituted C1-C. 30 Alkyl, substituted or unsubstituted C2-C 30 alkenyl, substituted or unsubstituted C2-C 30 Alkyne, substituted or unsubstituted C3-C 30 Cycloalkyl, substituted or unsubstituted 3- to 30-membered heterocyclic alkyl groups, wherein the heteroatoms are selected from oxygen, nitrogen, and sulfur; substituted or unsubstituted C6-C 30 Aryl, substituted or unsubstituted 3-20-membered heteroaryl groups, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur; substituted or unsubstituted 3-25-membered heteroarylamine groups, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur; substituted or unsubstituted C6-C 60 Arylamine group.

[0014] Preferably, the general formula 1 includes the following structure:

[0015]

[0016] In equations 1-1 to 1-4 above, Z1-Z3, L, Ar1, Ar2, and R1-R3 are defined in the same way as in general equation 1 above.

[0017] Preferably, L is selected from the following: linking bond, phenyl, tolyl, naphthyl, fluorenyl, phenanthrene, biphenyl, p-terphenyl, m-terphenyl, phenylnaphthyl, deuterated phenyl, pyridyl, or quinolinyl.

[0018] Preferably, Ar1 and Ar2 are the same or different from each other, and are each independently selected from phenyl, biphenyl, terphenyl, naphthyl, anthracene, phenanthryl, fluorenyl, pyridyl, thiazolyl, oxazolyl, furanyl, benzofuranyl, thiophene, benzothiophene, dibenzofuranyl, dibenzothiophene, phenylnaphthyl or quinolinyl.

[0019] Preferably, R1, R2, and R3 are the same as or different from each other, and each is independently selected from hydrogen, deuterium, halogen, cyano, carboxyl, nitro, hydroxyl, and amino; substituted or unsubstituted C1-C 10 Alkyl, substituted or unsubstituted C3-C 10 Cycloalkyl, substituted or unsubstituted 3- to 10-membered heterocyclic alkyl groups, wherein the heteroatoms are selected from oxygen, nitrogen, and sulfur; substituted or unsubstituted C6-C 18 Aryl, substituted or unsubstituted 3- to 10-membered heteroaryl groups, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur.

[0020] More preferably, the general formula 1 includes any one of the following structures, but is not limited thereto:

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028] Another object of the present invention is to provide a method for preparing the above-mentioned organic electroluminescent compound, the synthetic route of which is as follows:

[0029]

[0030] In the above formula, n, Z1, Z2, Z3, L, Ar1, Ar2, R1-R3 are defined as in general formula 1 above; Hal1-Hal3 are either the same as or different from each other and are independently selected from fluorine, chlorine, bromine, and iodine;

[0031] The preparation method is as follows:

[0032] Step 1: Preparation of Intermediate 1

[0033] Raw material B was dissolved in THF, then the gas was purged three times, the temperature was lowered to -78℃, n-BuLi was slowly added, the reaction was carried out for 4 hours, raw material A was added under nitrogen protection, the temperature was slowly raised to 25℃, and the mixture was stirred for 12 hours to prepare intermediate 1.

[0034] Step 2, Preparation of Intermediate 2

[0035] Intermediate 1 was dissolved in dichloromethane solution, boron trifluoride diethyl ether was added dropwise, the mixture was stirred until homogeneous, cooled to 0°C, and reacted for 2 hours to prepare intermediate 2.

[0036] Step 3, Preparation of Intermediate 3

[0037] Intermediate 2 and raw material C toluene, ethanol and water were mixed, then the mixture was purged 3 times, palladium catalyst and potassium carbonate were added under nitrogen protection, stirred evenly, heated to 90℃ and reacted for 6 hours to prepare intermediate 3.

[0038] Step 4, Preparation of Intermediate 4

[0039] Intermediate 3 was dissolved in carbon tetrachloride solution, BPO was added, NBS was slowly added, the mixture was stirred until homogeneous, the temperature was slowly raised to 80°C, and the reaction was carried out for 8 hours to prepare intermediate 4.

[0040] Step 5, Preparation of General Formula 1

[0041] Intermediate 4 and raw material D were added to a mixed solution of toluene, ethanol and water. After purging three times, palladium catalyst, phosphine ligand and cesium carbonate were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90°C and reacted for 6 hours to prepare general formula 1.

[0042] Preferably, step 1 specifically includes the following steps:

[0043] Raw material B was dissolved in THF, then ventilated 3 times, cooled to -78℃, and n-BuLi was slowly added. The reaction was carried out for 4 hours. Raw material A was added under nitrogen protection, the temperature was slowly raised to 25℃, and the mixture was stirred for 12 hours. Then, distilled water was 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 (1:4) to obtain intermediate 1.

[0044] Preferably, step 2 specifically includes the following steps:

[0045] Intermediate 1 was dissolved in dichloromethane solution, stirred until homogeneous, cooled to 0°C, and boron trifluoride ether was added dropwise. The reaction was allowed to proceed for 10 hours. After the reaction was completed, ethanol was 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 (1:20) to obtain intermediate 2.

[0046] Preferably, step 3 specifically includes the following steps:

[0047] In a mixed solution of intermediate 2 and raw material C (toluene, ethanol, and water), potassium carbonate and palladium catalyst were added under nitrogen protection after three purging cycles. The mixture was stirred until homogeneous, heated to 90°C, and refluxed for 6 hours. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalyst. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain a solid organic compound. The solid organic compound was completely dissolved in a small amount of dichloromethane and then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain a solid, which was then washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 3.

[0048] Preferably, step 4 specifically includes the following steps:

[0049] Intermediate 3 was dissolved in carbon tetrachloride solution and BPO was added. NBS was slowly added and stirred until homogeneous. The temperature was slowly raised to 80°C and reacted for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and the solvent was removed from the reaction solution using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:6) to obtain intermediate 4.

[0050] Preferably, step 5 specifically includes the following steps:

[0051] Under nitrogen protection, intermediate 4 and starting material D were dissolved in toluene, ethanol, and aqueous solution. Cesium carbonate, phosphine ligand, and palladium catalyst were added, and the mixture was stirred until homogeneous. The mixture was heated to 90°C and refluxed for 6 hours. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalyst. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substances were purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 4:1) to obtain general formula 1.

[0052] Another object of the present invention is to provide an electron transport layer comprising the above-mentioned organic electroluminescent compound.

[0053] And an organic electroluminescent device, the organic electroluminescent device comprising the electron transport layer described above.

[0054] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: The nitrogen-containing heterocyclic organic electroluminescent compound provided by the present invention, when used to prepare organic electroluminescent devices, has the advantages of low driving voltage, high efficiency, and long lifetime. Specifically, by using diazine and triazine functional groups with strong electron-withdrawing ability, the electron mobility of the electron transport material is effectively improved, thus alleviating the problem of electron-hole imbalance inside the organic electroluminescent device and improving luminous efficiency. Secondly, in addition to introducing diazine and triazine, a planar heteroaryl structure containing heteroatoms is introduced, further improving the electron mobility of the electron transport material. At the same time, the planar molecular structure prevents the π-conjugated system of the core structure from being continued, ensuring a high triplet energy level (ET) and a wide bandgap. This further improves luminous efficiency, improves the matching degree of energy levels in each layer of the device, reduces the driving voltage, and extends the device lifetime. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0056] Figure 1 The above is the hydrogen nuclear magnetic resonance spectrum of the compound in Example 1 of this invention;

[0057] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the compound in Example 2 of this invention;

[0058] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the compound in Example 3 of the present invention. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Example 1

[0061]

[0062] Raw material B (40.00 mmol) was dissolved in THF, then the mixture was purged three times, cooled to -78°C, and n-BuLi was slowly added. The reaction was allowed to proceed for 4 h. Raw material A (40.00 mmol) was added under nitrogen protection, 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 substance was purified by column chromatography using a mixed solution of DCM and PE (1:4) to obtain intermediate 1 (10.21 g, yield 75.34%).

[0063] Intermediate 1 (30.09 mmol) was dissolved in dichloromethane solution, stirred until homogeneous, cooled to 0 °C, and boron trifluoride diethyl ether (30.09 mmol) was added dropwise. The reaction was allowed to proceed for 10 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. 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 (1:20) to obtain intermediate 2 (7.95 g, yield 82.36%).

[0064] Intermediate 2 (24.74 mmol) and starting material C (27.21 mmol) were added to a mixed solution of toluene, ethanol, and water. After purging three times, potassium carbonate (49.48 mmol) and tetraphenylphosphine palladium (0.49 mmol) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90 °C, and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain a solid organic compound. The solid organic compound was completely dissolved in a small amount of dichloromethane and then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain a solid, which was washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 3 (7.77 g, yield 80.21%).

[0065] Intermediate 3 (19.82 mmol) was dissolved in carbon tetrachloride solution, BPO (1.98 mmol) was added, NBS (39.65 mmol) was slowly added, the mixture was stirred until homogeneous, the temperature was slowly raised to 80 °C, and the reaction was carried out for 8 h. After the reaction was completed, the temperature was lowered to room temperature, and the solvent was removed from the reaction solution using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:6) to obtain intermediate 4 (5.50 g, 71.31%).

[0066] Under nitrogen protection, intermediate 4 (14.10 mmol) and starting material D (14.10 mmol) were dissolved in toluene, ethanol, and aqueous solution. Cesium carbonate (28.20 mmol), X-Phos (0.70 mmol), and palladium acetate (0.70 mmol) were added, stirred until homogeneous, heated to 90 °C, and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature, washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, 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 = 4:1) to obtain compound 1 (6.55 g, yield 79.26%, MW: 586.70).

[0067] The obtained compound-1 was analyzed, and the results are as follows:

[0068] HPLC purity: >99.6%.

[0069] Mass spectrometry test: theoretical value 586.70; test value 586.51.

[0070] Elemental analysis:

[0071] The calculated values ​​are: C, 85.98; H, 4.47; N, 9.55.

[0072] The test values ​​are: C, 85.76; H, 4.68; N, 9.64.

[0073] Example 2

[0074]

[0075] Raw material B (40.00 mmol) was dissolved in THF, then the mixture was purged three times, cooled to -78°C, and n-BuLi was slowly added. The reaction was allowed to proceed for 4 h. Raw material A (40.00 mmol) was added under nitrogen protection, 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 substance was purified by column chromatography using a mixed solution of DCM and PE (1:4) to obtain intermediate 1 (10.74 g, yield 79.26%).

[0076] Intermediate 1 (31.65 mmol) was dissolved in dichloromethane solution, stirred until homogeneous, cooled to 0 °C, and boron trifluoride diethyl ether (31.65 mmol) was added dropwise. The reaction was allowed to proceed for 10 h. After the reaction was complete, ethanol was 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 (1:20) to obtain intermediate 2 (8.25 g, yield 81.29%).

[0077] Intermediate 2 (25.68 mmol) and starting material C (28.24 mmol) were added to a mixed solution of toluene, ethanol, and water. After purging three times, potassium carbonate (51.36 mmol) and tetraphenylphosphine palladium (0.51 mmol) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90 °C, and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain a solid organic compound. The solid organic compound was completely dissolved in a small amount of dichloromethane and then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain a solid, which was washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 3 (7.96 g, yield 79.14%).

[0078] Intermediate 3 (20.31 mmol) was dissolved in carbon tetrachloride solution, BPO (2.03 mmol) was added, NBS (40.62 mmol) was slowly added, the mixture was stirred until homogeneous, the temperature was slowly raised to 80 °C, and the reaction was carried out for 8 h. After the reaction was completed, the temperature was lowered to room temperature, and the solvent was removed from the reaction solution using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:6) to obtain intermediate 4 (5.32 g, 67.28%).

[0079] Under nitrogen protection, intermediate 4 (13.64 mmol) and starting material D (13.64 mmol) were dissolved in toluene, ethanol, and aqueous solution. Cesium carbonate (27.28 mmol), X-Phos (0.68 mmol), and palladium acetate (0.68 mmol) were added, and the mixture was stirred until homogeneous. The mixture was heated to 90 °C and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, 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 = 4:1) to obtain compound 13 (8.02 g, yield 79.66%, MW: 738.89).

[0080] The obtained compound-13 was analyzed, and the results are as follows:

[0081] HPLC purity: >99.7%.

[0082] Mass spectrometry test: theoretical value 738.89; test value 738.61.

[0083] Elemental analysis:

[0084] The calculated values ​​are: C, 87.78; H, 4.64; N, 7.58.

[0085] Test values: C, 87.62; H, 4.71; N, 7.69

[0086] Example 3

[0087]

[0088] Raw material B (40.00 mmol) was dissolved in THF, then the mixture was purged three times, cooled to -78°C, and n-BuLi was slowly added. The reaction was allowed to proceed for 4 h. Raw material A (40.00 mmol) was added under nitrogen protection, 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 substance was purified by column chromatography using a mixed solution of DCM and PE (1:4) to obtain intermediate 1 (10.86 g, yield 80.16%).

[0089] Intermediate 1 (32.01 mmol) was dissolved in dichloromethane solution, stirred until homogeneous, cooled to 0 °C, and boron trifluoride diethyl ether (32.01 mmol) was added dropwise. The reaction was allowed to proceed for 10 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. 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 (1:20) to obtain intermediate 2 (8.28 g, yield 80.57%).

[0090] Intermediate 2 (25.77 mmol) and starting material C (28.34 mmol) were added to a mixed solution of toluene, ethanol, and water. After purging three times, potassium carbonate (51.54 mmol) and tetraphenylphosphine palladium (0.51 mmol) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90 °C, and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain a solid organic compound. The solid organic compound was completely dissolved in a small amount of dichloromethane and then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain a solid, which was washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 3 (7.76 g, yield 76.92%).

[0091] Intermediate 3 (19.80 mmol) was dissolved in carbon tetrachloride solution, BPO (1.98 mmol) was added, NBS (39.60 mmol) was slowly added, the mixture was stirred until homogeneous, the temperature was slowly raised to 80 °C, and the reaction was carried out for 8 h. After the reaction was completed, the temperature was lowered to room temperature, and the solvent was removed from the reaction solution using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:6) to obtain intermediate 4 (5.19 g, 67.32%).

[0092] Under nitrogen protection, intermediate 4 (13.31 mmol) and starting material D (13.31 mmol) were dissolved in toluene, ethanol, and aqueous solution. Cesium carbonate (26.62 mmol), X-Phos (0.66 mmol), and palladium acetate (0.66 mmol) were added, and the mixture was stirred until homogeneous. The mixture was heated to 90 °C and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried over anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. The remaining substance was purified by column chromatography using a mixture of dichloromethane and petroleum ether (V:V = 4:1) to obtain compound 28 (6.73 g, yield 76.34%, MW: 662.80).

[0093] The obtained compound-28 was analyzed, and the results are as follows:

[0094] HPLC purity: >99.6%.

[0095] Mass spectrometry test: theoretical value 662.80; test value 663.16.

[0096] Elemental analysis:

[0097] The calculated values ​​are: C, 86.98; H, 4.56; N, 8.45.

[0098] Test values: C, 86.76; H, 4.73; N, 8.61

[0099] Example 4

[0100]

[0101] Raw material B (40.00 mmol) was dissolved in THF, then purged three times, cooled to -78°C, and n-BuLi was slowly added. The reaction was allowed to proceed for 4 h. Raw material A (40.00 mmol) was added under nitrogen protection, 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 substance was purified by column chromatography using a mixed solution of DCM and PE (1:4) to obtain intermediate 1 (9.98 g, yield 73.67%).

[0102] Intermediate 1 (29.41 mmol) was dissolved in dichloromethane solution, stirred until homogeneous, cooled to 0 °C, and boron trifluoride diethyl ether (29.41 mmol) was added dropwise. The reaction was allowed to proceed for 10 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. 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 (1:20) to obtain intermediate 2 (7.95 g, yield 84.31%).

[0103] Intermediate 2 (24.74 mmol) and starting material C (27.21 mmol) were added to a mixed solution of toluene, ethanol, and water. After purging three times, potassium carbonate (49.48 mmol) and tetraphenylphosphine palladium (0.49 mmol) were added under nitrogen protection. The mixture was stirred until homogeneous, heated to 90 °C, and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain a solid organic compound. The solid organic compound was completely dissolved in a small amount of dichloromethane and then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain a solid, which was washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 3 (7.88 g, yield 81.39%).

[0104] Intermediate 3 (20.10 mmol) was dissolved in carbon tetrachloride solution, BPO (2.01 mmol) was added, NBS (40.20 mmol) was slowly added, the mixture was stirred until homogeneous, the temperature was slowly raised to 80 °C, and the reaction was carried out for 8 h. After the reaction was completed, the temperature was lowered to room temperature, and the solvent was removed from the reaction solution using a rotary evaporator. The remaining substance was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:6) to obtain intermediate 4 (4.95 g, 63.34%).

[0105] Under nitrogen protection, intermediate 4 (12.69 mmol) and starting material D (12.69 mmol) were dissolved in toluene, ethanol, and aqueous solution. Cesium carbonate (25.38 mmol), X-Phos (0.63 mmol), and palladium acetate (0.63 mmol) were added, and the mixture was stirred until homogeneous. The mixture was heated to 90 °C and refluxed for 6 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, 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 = 4:1) to obtain compound 75 (7.41 g, yield 79.16%, MW: 738.89).

[0106] The obtained compound-75 was analyzed, and the results are as follows:

[0107] HPLC purity: >99.6%.

[0108] Mass spectrometry test: theoretical value 738.89; test value 738.64.

[0109] Elemental analysis:

[0110] The calculated values ​​are: C, 87.78; H, 4.64; N, 7.58.

[0111] The test values ​​are: C, 87.59; H, 4.76; N, 7.71.

[0112] 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:

[0113] Table 1

[0114]

[0115]

[0116] Device Example 1: Fabrication of an organic electroluminescent device containing compound 1

[0117] a. ITO Anode: A 150nm thick ITO (Indium Tin Oxide)-Ag-ITO (Indium Tin Oxide) glass substrate is cleaned twice with distilled water, ultrasonically washed for 30 minutes, then repeatedly cleaned twice with distilled water, ultrasonically washed for 10 minutes. After washing, it is transferred to a spin dryer for drying, and finally baked in a vacuum oven at 220℃ for 2 hours. After baking, it is cooled before use. Using this substrate as the anode, a vapor deposition process is performed to deposit other functional layers sequentially on it.

[0118] b. HIL (Hole Injection Layer): The evaporation rate of the hole injection layer material 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.

[0119] c. 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, and the structure is shown in the figure.

[0120] d. Light-emitting auxiliary layer: with The evaporation rate was such that a 10 nm EBL-1 was vacuum-deposited on the hole transport layer as a light-emitting auxiliary layer;

[0121] e. EML (Emitting Layer): Then, on the above-mentioned emitting auxiliary layer, with... The evaporation rate was determined by vacuum evaporation of a host material and a dopant material with a thickness of 20 nm as the light-emitting layer. The chemical formulas of the host and dopant are shown below. The evaporation rate ratio of the host to the dopant is 98:2.

[0122] f. HBL (Hole Blocking Layer): At a certain evaporation rate, a 5nm HB-1 layer was vacuum-deposited on the light-emitting layer as a hole-blocking layer, as shown in the figure:

[0123] g. ETL (Electron Transport Layer): The above-described embodiment of compound 1 was used as an electron transport layer by vacuum evaporating 30 nm onto the hole blocking layer at a certain evaporation rate.

[0124] h, EIL (Electron Injection Layer): with The evaporation rate was such that a Yb film layer of 1.0 nm was deposited to form an electron injection layer.

[0125] i. Cathode: with The evaporation rate ratio of magnesium and silver at 18nm was 1:9, resulting in an OLED device.

[0126] j. Optical extraction layer: with The evaporation rate was adjusted to vacuum-deposit a 70nm thick CPL-1 layer on the cathode as a light extraction layer. The deposited substrate was then encapsulated. First, a UV adhesive was applied to the cleaned cover plate using a coating machine. Then, the coated cover plate was moved to the lamination section, and the evaporated substrate was placed on top of the cover plate. Finally, the substrate and cover plate were bonded together using a bonding machine, while simultaneously curing the UV adhesive.

[0127] The structural formula of the materials used is shown below:

[0128]

[0129] Device Examples 2-36: Following the method described above, compound 1 used in Device Example 1 was replaced with compounds 13, 28, 75, 6, 10, 16, 20, 22, 26, 30, 34, 38, 39, 42, 45, 48, 50, 55, 61, 68, 76, 84, 93, 100, 101, 107, 111, 119, 124, 128, 131, 138, 141, 150, and 163 as electron transport layers to prepare the corresponding organic electroluminescent devices.

[0130] Comparative Example 1: This comparative example provides an organic electroluminescent device. The only difference between this organic electroluminescent device and Device Example 1 is that the organic electroluminescent device uses existing comparative compounds a and b to replace the electron transport layer (compound 1) in Device Example 1 for vapor deposition, thus preparing Comparative Examples 1-2. The chemical structural formulas of comparative compounds a and b are as follows:

[0131]

[0132] The driving voltage, luminous efficiency, BI value, and lifetime of the organic electroluminescent devices obtained in Examples 1-36 and Comparative Examples 1-2 were characterized at a brightness of 1000 nits. The test results are shown in Table 2 below.

[0133] Table 2

[0134]

[0135]

[0136]

[0137] As can be seen from the table above, the organic electroluminescent device prepared by using the organic electroluminescent compound provided by the present invention as the electron transport layer has a lower start-up voltage and significantly improved luminous efficiency and lifetime compared with the organic electroluminescent device prepared by using compounds a and b as the electron transport layer.

[0138] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0139] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not 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. An organic electroluminescent compound, characterized in that, The general structural formula is shown in Formula 1: Where n is 1; Z1-Z3 are each independently selected from C or N, and at least one of them is N; L is selected from the linking bond, phenylene, naphthylene, biphenyl, or phenylnaphthyl; Ar1 and Ar2 may be the same as or different from each other, and each is independently selected from phenyl, biphenyl, terphenyl, fluorenyl, naphthyl, pyridyl, dibenzothiophene, or dibenzofuranyl; R1, R2, and R3 are all hydrogen.

2. The organic electroluminescent compound according to claim 1, characterized in that... General Formula 1 includes the following structure:

3. An electron transport layer, characterized in that, The electron transport layer comprises the organic electroluminescent compound as described in claim 1 or 2.

4. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes the electron transport layer as described in claim 3.

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