An organic electroluminescent compound and its preparation method, organic electroluminescent device and display device

Abstract

The present application provides an organic electroluminescent compound and a preparation method thereof, an organic electroluminescent device and a display device, and relates to the field of organic electroluminescent technology. The general structural formula of the organic electroluminescent compound is: wherein, M is selected from O or S; R1-R6 are each independently selected from an aryl group consisting of carbon and hydrogen containing 6-60 carbon atoms; the hydrogen in the aryl group is each independently substituted or unsubstituted by an aliphatic alkyl group or an aliphatic alkoxy group of 1-30 carbon atoms; the hydrogens other than R1-R6 are each independently substituted or unsubstituted by deuterium, F, CN. The organic electroluminescent compound has a lower driving voltage, a higher current efficiency and a longer life.

Description

Technical Field

[0001] The present application relates to the technical field of organic electroluminescence, and in particular to an organic electroluminescent compound and a preparation method thereof, an organic electroluminescent device and a display device. Background Art

[0002] Currently, organic electroluminescent (OLED) display technology has been applied in smart phones, tablet computers and other fields, and will be further expanded to large-size application fields such as televisions. In the past 30 years of development, people have developed various OLED materials with excellent performance, and through different designs of device structures and optimization of device performance such as life and efficiency, the commercialization process of OLED has been accelerated, making OLED widely used in the display and lighting fields.

[0003] OLEDs inject electrons from a cathode serving as an electron injection electrode and holes from an anode serving as a hole injection electrode into an emitting material layer (EML), so that electrons and holes combine to generate excitons, and the excitons are converted from an excited state to a ground state to emit light; a flexible substrate such as a plastic substrate can be used as a base substrate in which elements are formed. In addition, an organic light-emitting display device can operate at a voltage lower than that required to operate other display devices (e.g., 10V or less); an organic light-emitting display device has advantages in terms of power consumption and color perception.

[0004] The OLED includes a first electrode as an anode over a substrate, a second electrode spaced apart from and facing the first electrode, and an organic light emitting layer therebetween. However, the materials in the current organic light emitting layer still have limitations in terms of the lifespan of the OLED.

[0005] Therefore, in order to meet people's higher requirements for OLED devices, the field is in urgent need of developing more types of OLED materials with higher performance. Summary of the invention

[0006] The purpose of the present application is to provide an organic electroluminescent compound and a preparation method thereof, an organic electroluminescent device and a display device to solve the above problems.

[0007] To achieve the above objectives, the present application provides an organic electroluminescent compound in a first aspect, the general structural formula of which is:

[0008]

[0009] Wherein, M is selected from O or S;

[0010] R 1 -R 6Each independently selected from an aromatic group consisting of carbon and hydrogen containing 6 to 60 carbon atoms;

[0011] The hydrogen atoms in the aromatic groups are each independently substituted or unsubstituted by an aliphatic alkyl group or an aliphatic alkoxy group having 1 to 30 carbon atoms;

[0012] Except R 1 -R 6 The remaining hydrogen atoms are independently replaced by deuterium, F, or CN or not.

[0013] Optionally, the R 1 -R 6 Each is independently selected from phenyl, naphthyl, anthracenyl, phenanthryl, 9,9-dialkyl substituted fluorenyl, 9,9-diphenyl substituted fluorenyl, biphenyl, binaphthyl, bianthracenyl, bifluorenyl, terphenyl, triphenylene, fluoranthenyl, triphenylene, hydrogenated benzanthracenyl, indenofluorenyl, alkyl or aryl substituted indenofluorenyl.

[0014] Optionally, the R 1 -R 6 Each is independently selected from phenyl, naphthyl, biphenyl and 9,9-dimethylfluorenyl.

[0015] Optionally, the organic electroluminescent compound is selected from:

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031] The second aspect of the present application provides a method for preparing the organic electroluminescent compound, comprising:

[0032] Performing a first Suzuki-Miyaura reaction on 1-methoxy-2-iodo-4-bromonaphthalene and 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) to obtain a first intermediate;

[0033] The first intermediate, polyhalogen element-substituted iodonaphthalene, and a second organic solvent are subjected to a second Suzuki-Miyaura reaction to obtain a second intermediate;

[0034] Demethylating the second intermediate to obtain a third intermediate containing a phenol group;

[0035] The phenolic compound is subjected to a benzofuran synthesis reaction to obtain a fourth intermediate;

[0036] The fourth intermediate and 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) are subjected to a third Suzuki-Miyaura reaction to obtain a fifth intermediate;

[0037] The fifth intermediate, phenanthroline substituted with a halogen element, is subjected to a fourth Suzuki-Miyaura reaction to obtain an organic electroluminescent compound.

[0038] Optionally, when the number of halogen elements in the polyhalogen-substituted iodonaphthalene is greater than or equal to 3, the method for preparing the organic electroluminescent compound further comprises:

[0039] The product obtained by the fourth Suzuki-Miyaura reaction is subjected to a fifth Suzuki-Miyaura reaction with a boron-containing compound.

[0040] Optionally, the catalysts used in the first Suzuki-Miyaura reaction, the second Suzuki-Miyaura reaction, the third Suzuki-Miyaura reaction, the fourth Suzuki-Miyaura reaction, and the fifth Suzuki-Miyaura reaction are each independently selected as a palladium-based compound.

[0041] In some embodiments, palladium-based compounds include but are not limited to Pd(PPh 3 ) 4 , PdCl2 (PPh 3 ) 2 .

[0042] Optionally, the benzofuran synthesis reaction is carried out under alkaline conditions.

[0043] It should be noted that the benzofuran synthesis reaction is that the phenolic hydroxyl group forms an oxygen anion in the presence of a strong base, which then attacks the carbon cation on the C-halogen element, and then the halogen element leaves to form a furan ring.

[0044] The third aspect of the present application provides an organic electroluminescent device, comprising the organic electroluminescent compound.

[0045] A fourth aspect of the present application provides a display device, comprising the organic electroluminescent device.

[0046] Compared with the prior art, the beneficial effects of this application include:

[0047] The organic electroluminescent compound provided in this application has the following advantages:

[0048] 1. High electron mobility: The organic electroluminescent compound has high electron mobility, which helps to improve the carrier balance of the organic electroluminescent device (OLED), thereby improving the luminous efficiency and life of the device;

[0049] 2. Thermal stability: The introduction of a rigid ring structure can improve the thermal stability of organic electroluminescent compounds, allowing them to maintain good performance at high temperatures and extend the service life of the device;

[0050] 3. Energy level regulation: By introducing electron-absorbing substituents, the energy level of the organic electroluminescent compound can be regulated to improve the energy level matching between the light-emitting layer and the electrode, thereby reducing the driving voltage of the device;

[0051] 4. Intermolecular π-π stacking: By introducing a cyclic structure, the compound can enhance the π-π stacking effect between molecules, form an effective electron transfer channel, and further improve the electron transfer performance.

[0052] The method for preparing the organic electroluminescent compound provided in the present application has low preparation cost, high yield, easy purification, mild reaction conditions, and convenient and simple post-treatment and easy operation.

[0053] The organic electroluminescent device and display device provided in the present application have lower driving voltage, higher current efficiency and longer lifespan. DETAILED DESCRIPTION

[0054] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0055] Example 1

[0056] This embodiment provides an organic electroluminescent compound A-1, the structural formula of which is:

[0057]

[0058] Among them, M is O.

[0059] This embodiment also provides a method for preparing an organic electroluminescent compound A-1, and the reaction is as follows:

[0060]

[0061] The specific steps are as follows:

[0062] S1. Synthesis of intermediate M-1-0: In a flask, add 1-methoxy-2-iodo-4-bromonaphthalene (108.6 g, 0.3 mol), 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) (83.8 g, 0.33 mol), PdCl 2 (PPh 3 ) 2 (4.2 g, 6 mmol), KOAc (88.2 g, 0.9 mol) and toluene (1000 mL), the mixture was heated to 100 ° C and cooled to room temperature after 8 hours, 1000 mL of water was added, stirred, and the organic phase was concentrated to dryness, 200 mL of toluene was added, the temperature was raised to 70 ° C and stirred to dissolve, the temperature was lowered to room temperature, 1000 mL of n-heptane was added, stirred for 1 h, frozen for 4 h, filtered, and the filter cake was dried in vacuum to obtain intermediate M-1-0 (73.8 g);

[0063] The mass spectrum data of the intermediate M-1-0 was tested, and the mass spectrum m / z was measured to be 362.07;

[0064] S2. Synthesis of intermediate M-1-1: In a flask, add M-1-0 (72.4 g, 0.2 mol), 4-bromo-1-fluoro-2-iodonaphthalene (84 g, 0.24 mol), Pd (PPh 3 ) 4(4.62g, 4mmol), sodium carbonate (63.4g, 0.6mol), toluene (560mL) and water (168mL), the mixture was heated to 40℃ for reaction for 2 hours, then heated to 60℃ for reaction for 2 hours, then heated to reflux for reaction for 2 hours, then cooled to room temperature, 800mL of n-heptane and 800mL of water were added, solid was precipitated, stirred, filtered, the filter cake was heated to 100℃ with 800mL of toluene and stirred for 1h, cooled to room temperature, filtered, and the filter cake was vacuum dried to obtain intermediate M-1-1 (77.9g);

[0065] The mass spectrum data of the intermediate M-1-1 was tested, and the mass spectrum m / z was measured to be 457.93;

[0066] S3. Synthesis of intermediate M-1-2: In a flask, add M-1-1 (68.7 g, 0.15 mol) and DCM (700 mL), cool to 0 ° C, add boron tribromide (56.4 g, 0.225 mol) dropwise, stir the mixture at room temperature for 16 hours, cool to -78 ° C, slowly add 100 mL of methanol dropwise, warm to room temperature, add 700 mL of water and 700 ml of DCM, stir for 30 min, stand for stratification, concentrate the organic phase to dryness, add ethanol and stir for 30 min, filter, and dry the filter cake in vacuum to obtain M-2 (55 g);

[0067] The mass spectrum data of the intermediate M-1-2 was tested, and the mass spectrum m / z was measured to be 443.92;

[0068] S4. Synthesis of intermediate M-1-3

[0069] In a flask, add M-1-2 (44.4 g, 0.1 mol), potassium carbonate (27.6 g, 0.2 mol) and NMP (500 ml). Heat the mixture to 180 ° C and cool to room temperature after 4 hours. Add 1000 ml of toluene and 1000 ml of water, stir, stand and separate, wash the organic layer once with 1000 ml of water, concentrate the organic phase to dryness, add 500 ml of ethanol and stir for 30 minutes, filter, and vacuum dry the filter cake to obtain intermediate M-1-3 (31.8 g).

[0070] The mass spectrum data of the intermediate M-1-3 was tested, and the mass spectrum m / z was measured to be 423.91.

[0071] S4. Synthesis of intermediate M-1-4: In a flask, add M-1-3 (30 g, 0.07 mol), 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) (44.5 g, 0.175 mol), PdCl 2 (PPh 3 ) 2(1.47 g, 2.1 mmol), KOAc (20.6 g, 0.21 mol) and toluene (600 mL), the mixture was heated to 100 ° C and cooled to room temperature after 8 hours, 600 mL of n-heptane and 600 mL of water were added, stirred, a large amount of solid precipitated, filtered, the filter cake was heated to 100 ° C with 600 mL of toluene and stirred for 1 h, cooled to room temperature, filtered, and the filter cake was vacuum dried to obtain intermediate M-1-4 (26.2 g);

[0072] The mass spectrum data of intermediate M-1-4 was tested, and the mass spectrum m / z was measured to be 520.26;

[0073] S5. Synthesis of compound A-1: ​​intermediate M-1-4 (26 g, 0.05 mol), 5-bromo-1,10-phenanthroline (29.8 g, 0.115 mol), tris(dibenzylideneacetone)dipalladium (1.06 g, 1.5 mmol), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (1.43 g, 3 mmol), sodium tert-butoxide (14.4 g, 150 mmol), xylene (600 mL) were added Pour into the reaction bottle, under nitrogen protection, reflux reaction for 12h, the reaction is completed, cool to room temperature, add 600mL of n-heptane and 600mL of water, stir for 30min, a large amount of solid precipitates, filter, stir the filter cake with 600mL of water for 30min, filter, stir the filter cake with 600mL of ethanol for 30min, filter, heat the filter cake with 800mL of toluene to 100°C and stir for 1h, cool to room temperature, filter, and vacuum dry the filter cake to obtain compound A-1 (25.6g);

[0074] The mass spectrum data of compound A-1 was subjected to mass spectrum testing, and the mass spectrum m / z was measured to be 624.2.

[0075] Example 2

[0076] This embodiment provides an organic electroluminescent compound A-2, the structural formula of which is:

[0077]

[0078] Among them, M is O.

[0079] This embodiment also provides a method for preparing an organic electroluminescent compound A-2. The method for preparing the intermediate M-1-0 is consistent with that in Example 1. The subsequent reaction process for preparing the organic electroluminescent compound A-2 based on the intermediate M-1-0 is as follows:

[0080]

[0081] The specific steps are as follows:

[0082] S1. Synthesis of intermediate M-2-1: In a flask, add M-1-0 (72.4 g, 0.2 mol), 2-bromo-1-chloro-4-fluoro-3-iodonaphthalene (92.2 g, 0.24 mol), Pd (PPh 3 ) 4 (4.62g, 4mmol), sodium carbonate (63.4g, 0.6mol), toluene (560mL) and water (168mL), the mixture was heated to 40℃ for 2 hours, then heated to 60℃ for 2 hours, then heated to reflux for 2 hours, then cooled to room temperature, 800mL of n-heptane and 800mL of water were added, solid was precipitated, stirred, filtered, the filter cake was heated to 100℃ with 800mL of toluene and stirred for 1h, cooled to room temperature, filtered, and the filter cake was vacuum dried to obtain intermediate M-2-1 (77.7g);

[0083] The mass spectrum data of the intermediate M-2-1 was tested, and the mass spectrum m / z was measured to be 491.89;

[0084] S2. Synthesis of intermediate M-2-2: In a flask, add M-2-1 (73.4 g, 0.15 mol) and DCM (750 mL), cool to 0°C, drop boron tribromide (56.4 g, 0.225 mol), and stir the mixture at room temperature for 16 hours. Cool to -78°C, slowly drop 100 mL of methanol, warm to room temperature, add 700 mL of water and 700 mL of DCM, stir for 30 min, stand and separate, concentrate the organic phase to dryness, add ethanol, stir for 30 min, filter, and vacuum dry the filter cake to obtain M-2-2 (52.2 g);

[0085] The mass spectrum data of the intermediate M-2-2 was tested, and the mass spectrum m / z was measured to be 477.88;

[0086] S3, synthesis of intermediate M-2-3: In a flask, add M-2-2 (47.8g, 0.1mol), potassium carbonate (27.6g, 0.2mol) and NMP (500mL), heat the mixture to 180°C and cool to room temperature after 4 hours, add 1000mL toluene and 1000mL water, stir, stand and separate, wash the organic layer once with 1000mL water, concentrate the organic phase to dryness, add 500mL ethanol and stir for 30min, filter, and dry the filter cake in vacuum to obtain intermediate M-2-3 (36.2g);

[0087] The mass spectrum data of the intermediate M-2-3 was tested, and the mass spectrum m / z was measured to be 457.87;

[0088] S4. Synthesis of intermediate M-2-4: In a flask, add M-2-3 (32 g, 0.07 mol), 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) (44.5 g, 0.175 mol), PdCl 2 (PPh 3 ) 2 (1.47 g, 2.1 mmol), KOAc (20.6 g, 0.21 mol) and toluene (600 mL), the mixture was heated to 100 ° C and cooled to room temperature after 8 hours, 600 mL of n-heptane and 600 mL of water were added, stirred, a large amount of solid precipitated, filtered, the filter cake was heated to 100 ° C with 600 mL of toluene and stirred for 1 h, cooled to room temperature, filtered, and the filter cake was vacuum dried to obtain intermediate M-2-4 (26.8 g);

[0089] The mass spectrum data of intermediate M-2-4 was tested, and the mass spectrum m / z was measured to be 554.22;

[0090] S5. Synthesis of intermediate M-2-5: In a flask, add M-2-4 (19.4 g, 0.035 mol), 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) (22.3 g, 0.088 mol), PdCl 2 (PPh 3 ) 2 (0.74 g, 1.05 mmol), KOAc (10.3 g, 0.105 mol) and toluene (400 mL), the mixture was heated to 100 ° C and cooled to room temperature after 8 hours, 400 mL of n-heptane and 400 mL of water were added, stirred, a large amount of solid precipitated, filtered, the filter cake was heated to 130 ° C with 600 mL of chlorobenzene and stirred for 1 h, cooled to room temperature, filtered, and the filter cake was vacuum dried to obtain intermediate M-2-5 (19.8 g);

[0091] The mass spectrum data of the intermediate M-2-5 was tested, and the mass spectrum m / z was measured to be 658.16;

[0092] S6. Synthesis of compound A-2: Intermediate M-2-5 (18.3 g, 27.8 mmol), phenylboronic acid (3.7 g, 30.6 mmol), Pd 2 dba 3 (0.76 g, 0.83 mmol), K 3 PO 4(17.7 g, 83.4 mmol), toluene (200 mL), ethanol (100 mL), and water (100 mL) were added to the reaction bottle, and the reaction was carried out at 85 ° C for 12 h under nitrogen protection. After the reaction was completed, 400 mL of n-heptane and 400 mL of water were added after cooling to room temperature, and the mixture was stirred for 30 min. The mixture was filtered, and the filter cake was stirred with 400 mL of water for 30 min, filtered, and the filter cake was stirred with 400 mL of ethanol for 30 min, filtered, and the filter cake was heated to 100 ° C with 800 mL of chlorobenzene and stirred for 1 h. The mixture was cooled to room temperature and filtered. The filter cake was dried in vacuo to obtain compound A-2 (15.4 g);

[0093] The mass spectrum data of compound A-2 was subjected to mass spectrum testing, and the mass spectrum m / z was measured to be 700.23.

[0094] Example 3

[0095] This embodiment provides an organic electroluminescent compound A-3, the structural formula of which is:

[0096]

[0097] Among them, M is O.

[0098] This example also provides a method for preparing an organic electroluminescent compound A-3. The method for preparing the intermediate M-2-5 is consistent with that in Example 2. The subsequent reaction process for preparing the organic electroluminescent compound A-3 based on the intermediate M-2-5 is as follows:

[0099]

[0100] The specific steps are as follows:

[0101] Intermediate M-2-5 (18.3 g, 27.8 mmol), 9,9-dimethylfluorene-2-boronic acid (7.3 g, 30.6 mmol), Pd 2 dba 3 (0.76 g, 0.83 mmol), K 3 PO 4 (17.7 g, 83.4 mmol), toluene (200 mL), ethanol (100 mL), and water (100 mL) were added to the reaction bottle, and the reaction was carried out at 85 ° C for 12 h under nitrogen protection. After the reaction was completed, 400 mL of n-heptane and 400 mL of water were added after cooling to room temperature, and the mixture was stirred for 30 min and filtered. The filter cake was stirred with 400 mL of water for 30 min and filtered. The filter cake was stirred with 400 mL of ethanol for 30 min and filtered. The filter cake was heated to 100 ° C with 800 mL of chlorobenzene and stirred for 1 h, cooled to room temperature, filtered, and the filter cake was dried in vacuo to obtain compound A-3 (14.7 g);

[0102] The mass spectrum data of compound A-3 was subjected to mass spectrum testing, and the mass spectrum m / z was measured to be 816.29.

[0103] Example 4

[0104] This embodiment provides an organic electroluminescent compound A-4, the structural formula of which is:

[0105]

[0106] Among them, M is O.

[0107] This example also provides a method for preparing an organic electroluminescent compound A-4. The method for preparing the intermediate M-1-4 is consistent with that in Example 1. The subsequent reaction process for preparing the organic electroluminescent compound A-4 based on the intermediate M-1-4 is as follows:

[0108]

[0109] The specific steps are as follows:

[0110] Intermediate M-1-4 (26 g, 0.05 mol), 5-bromo-2-phenyl-1,10-phenanthroline (38.4 g, 0.115 mol), tris(dibenzylideneacetone)dipalladium (1.06 g, 1.5 mmol), 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (1.43 g, 3 mmol), sodium tert-butoxide (14.4 g, 150 mmol), xylene (600 mL) were added Pour into the reaction bottle, under nitrogen protection, react at 155 ° C for 12 hours, the reaction is completed, cool to room temperature, add 600 mL of n-heptane and 600 mL of water, stir for 30 minutes, filter, stir the filter cake with 600 mL of water for 30 minutes, filter, stir the filter cake with 600 mL of ethanol for 30 minutes, filter, heat the filter cake to 100 ° C with 800 mL of toluene and stir for 1 hour, cool to room temperature, filter, and vacuum dry the filter cake to obtain compound A-4 (26.8 g);

[0111] The mass spectrum data of compound A-4 was tested, and the mass spectrum m / z was measured to be 776.26.

[0112] Comparative Example 1

[0113] This comparative example provides an organic electroluminescent compound Z-1, the structural formula of which is:

[0114]

[0115] Comparative Example 2

[0116] This comparative example provides an organic electroluminescent compound Z-2, the structural formula of which is:

[0117]

[0118] Comparative Example 3

[0119] This comparative example provides an organic electroluminescent compound Z-3, the structural formula of which is:

[0120]

[0121] Among them, the preparation method of organic electroluminescent compounds Z-1, Z-2, and Z-3 can refer to patent KR20190074099A.

[0122] The present application also provides an organic electroluminescent device, the preparation process of which is as follows:

[0123] S1: The glass substrate coated with the ITO transparent conductive layer (as the anode) is ultrasonically treated in a cleaning agent, then rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone and ethanol, and then baked in a clean environment until the water is completely removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam to improve the properties of the surface and enhance the binding ability with the hole injection layer;

[0124] S2: Place the glass substrate in a vacuum chamber and evacuate the chamber to a vacuum of 1×10 -5 -9×10 -4 Pa, vacuum evaporate NPB on the anode as a hole transport layer, the evaporation rate is 0.1nm / s, and the evaporation film thickness is 40nm;

[0125] S3: Vacuum evaporate EM1 on the hole transport layer as the organic light-emitting layer of the device, the evaporation rate is 0.1nm / s, and the total evaporation film thickness is 30nm;

[0126] S4: vacuum evaporating the organic electroluminescent compounds provided in Examples 1-4 and Comparative Examples 1-3 on the organic light-emitting layer to serve as the electron transport layer of the organic electroluminescent device; the evaporation rate is 0.1 nm / s, and the total evaporation film thickness is 30 nm;

[0127] S5: Vacuum evaporate 0.5 nm of LiF and 150 nm of Al on the electron transport layer as the electron injection layer and cathode.

[0128] Among them, the structural formulas of NPB and EM1 are:

[0129]

[0130] The prepared organic electroluminescent device was tested for its brightness, driving voltage, current efficiency and life LT90, where LT90 refers to the time required for the brightness to drop to 90% of the original brightness while maintaining the current density at the initial brightness of 1000nit. The test items include the brightness, driving voltage, and current efficiency of the organic electroluminescent device. The driving voltage, current efficiency, and LT90 data are all based on a brightness of 1000cd / m 2 The specific test results are shown in Table 1.

[0131] Table 1 Test results

[0132]

[0133] analyze:

[0134] It can be seen from the data in Table 1 that compared with Comparative Examples 1-3, the organic electroluminescent devices prepared by using the organic electroluminescent compounds provided in the Examples as electron transport materials in Examples 1-4 have lower driving voltage, higher current efficiency and longer life.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

[0136] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. An organic electroluminescent compound, characterized in that: Its general structural formula is: Wherein, M is selected from O or S; R1-R6 are each independently selected from an aromatic group consisting of carbon and hydrogen containing 6 to 60 carbon atoms; The hydrogen atoms in the aromatic groups are each independently substituted or unsubstituted by an aliphatic alkyl group or an aliphatic alkoxy group having 1 to 30 carbon atoms; The hydrogen atoms other than R1 to R6 are independently substituted by deuterium, F, or CN or not.

2. The organic electroluminescent compound according to claim 1, characterized in that The R1-R6 are each independently selected from phenyl, naphthyl, anthracenyl, phenanthryl, 9,9-dialkyl substituted fluorenyl, 9,9-diphenyl substituted fluorenyl, biphenyl, binaphthyl, anthracenyl, bifluorenyl, terphenyl, triphenylene, fluoranthenyl, triphenylene, hydrogenated benzanthryl, indenofluorenyl, alkyl or aryl substituted indenofluorenyl.

3. The organic electroluminescent compound according to claim 2, characterized in that: The R1-R6 are each independently selected from phenyl, naphthyl, biphenyl, and 9,9-dimethylfluorenyl.

4. The organic electroluminescent compound according to claim 1, characterized in that The organic electroluminescent compound is selected from:

5. A method for preparing the organic electroluminescent compound according to any one of claims 1 to 4, characterized in that: include: Performing a first Suzuki-Miyaura reaction on 1-methoxy-2-iodo-4-bromonaphthalene and 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) to obtain a first intermediate; The first intermediate, polyhalogen element-substituted iodonaphthalene, and a second organic solvent are subjected to a second Suzuki-Miyaura reaction to obtain a second intermediate; Demethylating the second intermediate to obtain a third intermediate containing a phenol group; Subjecting the third intermediate containing a phenol group to a benzofuran synthesis reaction to obtain a fourth intermediate; The fourth intermediate and 4,4,4',4',5,5,5',5'octamethyl 2,2'bis(1,3,2-dioxaborolane) are subjected to a third Suzuki-Miyaura reaction to obtain a fifth intermediate; The fifth intermediate, phenanthroline substituted with a halogen element, is subjected to a fourth Suzuki-Miyaura reaction to obtain an organic electroluminescent compound.

6. The method for preparing an organic electroluminescent compound according to claim 5, characterized in that: When the number of halogen elements in the polyhalogen-substituted iodonaphthalene is greater than or equal to 3, the method for preparing the organic electroluminescent compound further comprises: The product obtained by the fourth Suzuki-Miyaura reaction is subjected to a fifth Suzuki-Miyaura reaction with a boron-containing compound.

7. The method for preparing an organic electroluminescent compound according to claim 6, characterized in that: The catalysts used in the first Suzuki-Miyaura reaction, the second Suzuki-Miyaura reaction, the third Suzuki-Miyaura reaction, the fourth Suzuki-Miyaura reaction, and the fifth Suzuki-Miyaura reaction are each independently selected as a palladium-based compound.

8. The method for preparing an organic electroluminescent compound according to any one of claims 5 to 7, characterized in that: The benzofuran synthesis reaction is carried out under alkaline conditions.

9. An organic electroluminescent device, characterized in that: The organic electroluminescent compound comprises the organic electroluminescent compound according to any one of claims 1 to 4.

10. A display device, characterized in that: The organic electroluminescent device according to claim 9 is included.

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