Organometallic compound, preparation method thereof and organic electroluminescent device

Abstract

The invention provides an organic metal compound, a preparation method thereof and an organic electroluminescent device, and the organic metal compound has a structure as shown in a general formula I. After the organic metal compound is used as a specific doping material of a luminescent layer and is applied to the organic electroluminescent device, the starting voltage of the device is reduced, and the performance of the device is improved. Therefore, carrier migration is avoided, the driving voltage is obviously reduced, the luminous efficiency is obviously improved, and the service life is obviously prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic electroluminescent materials, and relates to an organometallic compound, a preparation method thereof, and an organic electroluminescent device. Background Art

[0002] Organic electronic devices include but are not limited to the following types: organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), organic light-emitting transistors (OLETs), organic photovoltaic devices (OPVs), dye-sensitized solar cells (DSSCs), organic optical detectors, organic photoreceptors, organic field-effect quantum dots (OFQDs), light-emitting electrochemical cells (LECs), organic laser diodes, and organic electroluminescent devices.

[0003] In 1987, Tang and Van Slyke of Eastman Kodak reported a bilayer organic electroluminescent device, which includes an arylamine hole transport layer and a tris-8-hydroxyquinoline aluminum layer as an electron transport layer and a light-emitting layer. Once a bias voltage is applied to the device, green light is emitted from the device. This invention laid the foundation for the development of modern organic light-emitting diodes (OLEDs). The most advanced OLEDs can include multiple layers, such as charge injection and transport layers, charge and exciton blocking layers, and one or more light-emitting layers between the cathode and the anode. Since OLEDs are a self-luminous solid-state device, it provides great potential for display and lighting applications. In addition, the inherent properties of organic materials, such as their flexibility, can make them very suitable for special applications, such as fabrication on flexible substrates.

[0004] OLEDs can be divided into three different types according to their emission mechanisms. The OLED invented by Tang and van Slyke is a fluorescent OLED. It only uses singlet emission. The triplets generated in the device are wasted through non-radiative decay channels. Therefore, the internal quantum efficiency (IQE) of fluorescent OLEDs is only 25%. This limitation hinders the commercialization of OLEDs. Due to the spin-orbit coupling effect caused by the heavy atom effect, phosphorescent materials can utilize 75% of the triplet exciton energy in addition to 25% of the singlet, so they can harvest singlet and triplet energies and achieve 100% IQE (internal quantum efficiency). The discovery and development of phosphorescent OLEDs directly contributed to the commercialization of active matrix OLEDs (AMOLEDs). Recently, Adachi achieved high efficiency through thermally activated delayed fluorescence (TADF) of organic compounds. These emitters have a small singlet-triplet gap, making it possible for excitons to return from the triplet state to the singlet state. In TADF devices, triplet excitons can generate singlet excitons through reverse intersystem crossing, resulting in high IQE.

[0005] However, the problems of high driving voltage, low luminous efficiency, and short lifespan in organic light-emitting devices with phosphorescent materials severely limit the application of organic light-emitting devices. Therefore, how to develop a high-performance luminescent material that enables organic light-emitting devices to have comprehensive characteristics such as high efficiency, long lifespan, and low voltage is a technical problem that urgently needs to be solved by those in this field. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an organometallic compound, its preparation method, and an organic light-emitting device. By changing the combination of substituents on 2-(dibenzo[b,d]furan-4-yl)-4-isopropylpyridine and adding phenyl, fluorine-substituted biphenyl, branched alkyl, and substituted or unsubstituted cycloalkyl to generate an organometallic compound, the intermolecular spatial configuration is improved, and it has good spatial torsion ability, thus avoiding carrier migration. After using it as a specific doping material in the light-emitting layer and applying it to an organic light-emitting device, the turn-on voltage of the device is reduced, thereby avoiding carrier migration, and the driving voltage is significantly reduced, while the luminous efficiency and lifespan are significantly improved.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] On the one hand, the present invention provides an organometallic compound, and the organometallic compound has a structure shown in General Formula I:

[0009]

[0010] Wherein, R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen, -D, -T, -CN, -F, -CD3, -CF3, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C1-C40 alkoxy, trimethylgermanium, or trimethylsilicon, or any combination of at least two of them;

[0011] R7, R8, R9, R 10 、R 11 、R 12 、R 13 and R 14each independently selected from hydrogen, -D, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, unsubstituted C1-C6 alkyl, C1-C6 alkyl partially or fully substituted with deuterium, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C1-C40 alkoxy, trimethylgermyl or trimethylsilyl, or any combination of any one or at least two thereof;

[0012] Ra is

[0013] Rb is The dotted line represents the connection site of the group;

[0014] R 15 、R 16 、R 17 、R 18 、R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 and R 26 each independently selected from hydrogen, -D, -T, -CN, -F, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C2-C15 heterocyclic group, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C1-C40 alkoxy, trimethylgermyl or trimethylsilyl, or any combination of any one or at least two thereof;

[0015] Rc is selected from hydrogen, -D (deuterium), -T (tritium), -CN, -F, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C3-C40 cycloalkyl, substituted or unsubstituted C2-C40 alkenyl or alkynyl, substituted or unsubstituted C2-C40 heterocyclic group, substituted or unsubstituted C1-C40 alkoxy, trimethylgermyl or trimethylsilyl;

[0016] The hydrogen in the groups described in Formula I may be unsubstituted by deuterium or partially or fully substituted by deuterium.

[0017] In the present invention, D represents deuterium and T represents tritium.

[0018] Preferably, each of R1, R2, R3, R4, R5, and R6 is independently selected from hydrogen, -D, -CN, -F, -CF3, methyl, ethyl, propyl, butyl, neopentyl, cyclopentyl, cyclohexyl, phenyl, trimethylsilyl, trimethylgermyl, or the following groups:

[0019] any one or a combination of at least two thereof, * represents the attachment site of the group.

[0020] Preferably, each of R7, R8, R9, R 10 、R 11 、R 12 、R 13 、and R 14 is independently selected from hydrogen, -D, -CN, -F, -CD3, -CF3, methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, phenyl, deuterated phenyl, isobutyl, trimethylsilyl, trimethylgermyl, and any one or a combination of at least two of C1-C6 alkyl groups that are fully or partially substituted with deuterium.

[0021] In the present invention, the C1-C6 alkyl group fully substituted with deuterium is preferably -CD3;

[0022] Preferably, each of R 15 、R 16 、R 17 、R 18 、R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 、and R 26 is independently selected from -F, -CN, -D, methyl, ethyl, propyl, butyl, pentyl, cyclopropyl, cyclopentyl, phenyl, dibenzofuranyl, dibenzothiophenyl, biphenyl, naphthyl, phenyl substituted with C1-C6 alkyl, biphenyl substituted with C1-C6 alkyl, trimethylgermyl, trimethylsilyl, or any one or a combination of at least two thereof, * represents the attachment site of the group.

[0023] In the present invention, each of the C1-C6 alkyl groups is independently selected from a straight-chain alkyl group, a branched-chain alkyl group, or a cycloalkyl group; the C1-C6 alkyl group is partially deuterated, fully deuterated, or not deuterated.

[0024] In the present invention, the substituents on the substituted groups as described above are selected from one or a combination of at least two of -F, -CN, -D, -CD3, methyl, ethyl, propyl, butyl, pentyl, phenyl, naphthyl, dibenzofuranyl, dibenzothiophenyl, biphenyl, cyclopentyl, cyclohexyl, cyclopropyl, trimethylgermyl, trimethylsilyl or tetramethylcyclohexyl.

[0025] Preferably, the organometallic compound is preferably selected from one of the following structures, but not limited thereto:

[0026]

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[0082]

[0083] In the present invention, the preparation process of the organometallic compound of formula I is as follows:

[0084]

[0085] wherein R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、Ra, Rb and Rc are as defined above and will not be elaborated further.

[0086] Under nitrogen protection, compound of formula V and IrC13·3H2O are put into the reaction system, and a mixed solution of ethylene glycol monoethyl ether and pure water is added. The mixture is refluxed at 100°C to 120°C for 24 to 36 hours under nitrogen protection to obtain the compound of formula IV;

[0087] Silver trifluoromethanesulfonate is added to the compound of formula IV, and then dichloromethane and methanol are added to the system. The mixture is refluxed at 25°C to 30°C for 24 to 36 hours under nitrogen protection to obtain the compound of formula III;

[0088] The compound of formula II is added to the compound shown in formula III, and then absolute ethanol is added to the system. The mixture is refluxed at 70°C to 80°C for 24 to 36 hours under nitrogen protection to obtain the organometallic compound shown in formula I.

[0089] On the other hand, the present invention provides an organic electroluminescent device, which includes an anode, a cathode, and an organic material layer disposed between the anode and the cathode, and the organic material layer includes at least one of the above-mentioned organometallic compounds.

[0090] Preferably, the organic material layer includes a light-emitting layer, the light-emitting layer includes a host material and a dopant material, and the dopant material includes at least one of the above-mentioned organometallic compounds.

[0091] Preferably, the organic material layer further includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, or an electron injection layer.

[0092] Preferably, the organic electroluminescent device includes an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode which are sequentially disposed.

[0093] Generally, an organic electroluminescent device includes a first electrode (anode) and a second electrode (cathode), and an organic material layer located between the electrodes. The organic material can be further divided into multiple regions. For example, the organic material layer can include a hole transport region, a light-emitting layer, and an electron transport region.

[0094] In a specific embodiment, a substrate can be used below the first electrode or above the second electrode. The substrates are all glass or polymer materials with excellent mechanical strength, thermal stability, water resistance, and transparency. In addition, thin film transistors (TFTs) can also be provided on the substrate for display purposes.

[0095] The first electrode can be formed by sputtering or depositing a material used as the first electrode on the substrate. When the first electrode is used as an anode, oxide transparent conductive materials such as indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO2), zinc oxide (ZnO), etc., and any combination thereof can be used. In addition, the anode material can also be selected from materials and their combinations that are helpful for hole injection other than the listed anode materials, including known materials suitable for making an anode. When the first electrode is used as a cathode, metals or alloys such as magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), magnesium-silver (Mg-Ag), etc., and any combination thereof can be used. In addition to the above-listed cathode materials, the cathode material can also be a material and its combination that are helpful for electron injection, including known materials suitable for making a cathode.

[0096] The organic material layer can be formed on the electrode by methods such as vacuum thermal evaporation, spin coating, printing, etc. The compounds used as the organic material layer can be organic small molecules, organic macromolecules, polymers, and combinations thereof. The hole transport region is located between the anode and the light-emitting layer. The hole transport region can be a single-layer hole transport layer (HTL), including a single-layer hole transport layer containing only one compound and a single-layer hole transport layer containing multiple compounds. The hole transport region can also be a multi-layer structure including at least one of a hole injection layer (HIL), a hole transport layer (HTL), and an electron blocking layer (EBL).

[0097] The materials of the hole transport layer can be selected from, but not limited to, phthalocyanine derivatives such as CuPc, conductive polymers, or polymers containing conductive dopants such as poly(phenylene vinylene), polyaniline / dodecylbenzenesulfonic acid (PANI / DBSA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (PANI / CSA), polyaniline / poly(4-styrenesulfonate) (PANI / PSS), aromatic amine derivatives such as the compounds shown as HT-1 to HT-30 below, or any combination thereof.

[0098]

[0099]

[0100]

[0101] However, it is not limited to the above several materials.

[0102] The hole injection layer is located between the anode and the hole transport layer. The hole injection layer can be a single compound material or a combination of multiple compounds. For example, the hole injection layer can adopt one or more of the above compounds HT-1 to HT-30, or adopt one or more of the following compounds HI-1 to HI-3; it can also adopt one or more of the compounds HT-1 to HT-30 doped with one or more of the following compounds HI-1 to HI-3:

[0103]

[0104] However, it is not limited to the above several materials.

[0105] The OLED organic material layer can also include an electron transport region between the light-emitting layer and the cathode. The electron transport region can be a single-layer electron transport layer (ETL), including a single-layer electron transport layer containing only one compound and a single-layer electron transport layer containing multiple compounds. The electron transport region can also be a multi-layer structure including at least one of an electron injection layer (EIL), an electron transport layer (ETL), and a hole blocking layer (HBL).

[0106] In the present invention, the electron transport layer material may be selected from, but not limited to, one or more combinations of ET-1 to ET36 listed below:

[0107]

[0108]

[0109]

[0110] The device may further include an electron injection layer located between the electron transport layer and the cathode. The electron injection layer material includes, but is not limited to, one or more combinations of the following: LiF, NaCl, CsF, Li2O, Cs2CO3, BaO, Na, Li, Ca.

[0111] Compared with the prior art, the present invention has the following beneficial effects:

[0112] After the organometallic compound of the present invention is applied to the organic electroluminescent device, the turn-on voltage of the device is reduced, and the luminous efficiency and lifespan are significantly improved. Description of the Drawings

[0113] Figure 1 1H NMR spectrum of compound Z-1 prepared in Example 1. Detailed Description of the Embodiments

[0114] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0115] The technical solution will be clearly and completely described below in combination with the synthesis examples and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0116] In addition, it should be noted that the values given in the following embodiments are as accurate as possible. However, those skilled in the art should understand that due to inevitable measurement errors and experimental operation problems, each number should be understood as an approximate number rather than an absolutely accurate value.

[0117] Example 1

[0118]

[0119] Under nitrogen protection, 4-isopropylpyridin-2-ylboronic acid (CAS: 2833655-78-8, 1 eq) and anhydrous potassium carbonate (3 eq) were placed into the reaction system. Toluene, absolute ethanol, and pure water were added. Under nitrogen protection, Pd(PPh3)4 (0.015 eq) was added. 3,4,6-Trichlorodibenzofuran (CAS: 83704-43-2, 1 eq) was added in three batches every 1 hour. After addition, the mixture was refluxed at 100 °C for 24 h under nitrogen protection, and then cooled to 25 °C. After the reaction was cooled, it was extracted with ethyl acetate, washed three times with saturated brine, dried over anhydrous magnesium sulfate, concentrated under reduced pressure, and the crude product was subjected to column chromatography to remove impurities. The eluent was EA (ethyl acetate):PE (petroleum ether) volume ratio = 1:20. The receiving solution was rotated until no liquid flowed out and dried in vacuo to obtain the shown compound intermediate 1 with a yield of 18%.

[0120]

[0121] Under nitrogen protection, intermediate 1 (1 eq) and anhydrous potassium carbonate (3 eq) were placed into the reaction system. Toluene, absolute ethanol, and pure water were added. Under nitrogen protection, Pd(PPh3)4 (0.015 eq) was added. Phenylboronic acid (CAS: 98-80-8, 1 eq) was added in three batches every 1 hour. After addition, the mixture was refluxed at 100 °C for 24 h under nitrogen protection, and then cooled to 25 °C. After the reaction was cooled, it was extracted with ethyl acetate, washed three times with saturated brine, dried over anhydrous magnesium sulfate, concentrated under reduced pressure, and the crude product was subjected to column chromatography to remove impurities. The eluent was EA:PE volume ratio = 1:15. The receiving solution was rotated until no liquid flowed out and dried in vacuo to obtain the shown compound intermediate 1 with a yield of 39%.

[0122]

[0123] Under nitrogen protection, intermediate 2 (1 eq) and anhydrous potassium carbonate (3 eq) were placed into the reaction system. Toluene, absolute ethanol, and pure water were added. Under nitrogen protection, Pd(PPh3)4 (0.015 eq) was added. (4-Chloro-2,6-difluorophenyl)boronic acid (CAS: 925911-61-1, 1 eq) was added in three batches every 1 hour. After addition, the mixture was refluxed at 100 °C for 24 h under nitrogen protection, and then cooled to 25 °C. After the reaction was cooled, it was extracted with ethyl acetate, washed three times with saturated brine, dried over anhydrous magnesium sulfate, concentrated under reduced pressure, and the crude product was subjected to column chromatography to remove impurities. The eluent was EA:PE = 1:12. The receiving solution was rotated until no liquid flowed out and dried in vacuo to obtain the shown compound intermediate 3 with a yield of 72%.

[0124]

[0125] Under nitrogen protection, take intermediate 3 (1 eq) and anhydrous potassium carbonate (3 eq) and put them into the reaction system. Add toluene, absolute ethanol, and purified water. Under nitrogen protection, add Pd(PPh3)4 (0.015 eq). Add phenylboronic acid (CAS: 98 - 80 - 8, 1 eq) in three batches every 1 hour. After the addition is complete, reflux at 100 °C for 24 h under nitrogen protection. Then cool to 25 °C. After the reaction is cooled, extract with ethyl acetate, wash three times with saturated brine, dry over anhydrous magnesium sulfate, concentrate under reduced pressure, and subject the crude product to column chromatography to remove impurities. The eluent is EA:PE = 1:20. Rotate the receiving solution until no liquid flows out, and dry under vacuum to obtain the compound shown in Formula II - 1 with a yield of 75%.

[0126]

[0127] Under a nitrogen protection system, add compound 5 - methyl - 2 - phenylpyridine (CAS: 27012 - 22 - 2, 1 eq), DMSO - d6 (27 eq), and NaOH (1.1 eq). Replace the gas with nitrogen three times, and heat the reaction at 100 °C for 12 h under nitrogen protection. After the reaction is completed, extract with ethyl acetate, wash three times with saturated brine, and concentrate under reduced pressure. Subject the crude product to column chromatography to remove impurities. The eluent is EA:PE = 1:10. Rotate the receiving solution until no liquid flows out, and dry under vacuum to obtain the compound shown in Formula V - 1 with a yield of 96%.

[0128]

[0129] Under a nitrogen protection system, weigh compound V - 1 (1 eq) and IrC13·3H2O (0.4 eq) and put them into the reaction system. Add a mixed solution of ethylene glycol monoethyl ether and purified water. Reflux at 120 °C for 36 hours under nitrogen protection, then cool to room temperature. A precipitate will form. Filter the precipitate by suction, and wash and dry it successively with water, absolute ethanol, and petroleum ether to obtain the compound shown in Formula IV - 1 with a yield of 89%.

[0130]

[0131] Under a nitrogen protection system, weigh compound IV - 1 (1 eq), add silver trifluoromethanesulfonate (2.2 eq), then add dichloromethane and methanol to the system. Reflux at 25 °C for 36 hours under nitrogen protection and then cool to room temperature. Concentrate the filtrate of column chromatography until a solid precipitates to obtain compound III - 1 with a yield of 92%.

[0132]

[0133] Under a nitrogen protection system, weigh the compound of formula III-1 (1 eq), add the compound of formula II-1 (2.2 eq), then add absolute ethanol to the system, reflux at 70 °C for 36 hours under nitrogen protection, filter by suction, wash with alcohol, and dry. Use dichloromethane as the solvent, perform silica gel column chromatography, concentrate the filtrate to precipitate a solid, and obtain the final compound Z-1 (11.28 g, yield 52%).

[0134] HPLC purity: greater than 99.5%.

[0135] Mass spectrum: The calculated value is 1085.42.

[0136] The 1H NMR spectrum of the compound Z-1 prepared in Example 1 is as Figure 1 shown.

[0137] In addition, it should be noted that other compounds of the present invention can be obtained by referring to the synthesis methods of the above-listed examples, and will not be elaborated here one by one.

[0138] Device Example 1: Prepare an organic electroluminescent device using the organometallic compound of formula Z-1

[0139] Place the ITO glass substrate with a coating thickness of in distilled water and wash it 2 times, ultrasonically wash it for 30 minutes. After the distilled water washing is completed, ultrasonically wash it in sequence with solvents such as isopropanol, acetone, and methanol and then dry it. Transfer it to a plasma cleaner, wash the above substrate for 10 minutes, and send it to an evaporation coater. First, deposit a hole injection layer of HI-02 with a thickness of on the ITO (anode), then deposit a hole transport layer of HT-02 with a thickness of on the hole injection layer, immediately deposit a light-emitting layer of the host material 4,4'-N,N'-biphenyldicarbazole ("CBP") and the doping material compound of formula Z-1 in a weight ratio of 90:10, then deposit an electron transport layer of ET-02 with a thickness of on the light-emitting layer, immediately deposit an electron injection layer material Liq with a thickness of on the electron transport layer, and finally deposit a cathode material Al with a thickness of on the electron injection layer, and an organic electroluminescent device can be obtained. Test the performance and luminescence characteristics of the obtained device, and measure using a KEITHLEY 2400 source measurement unit and a CS-2000 spectro-radiance meter to evaluate the driving voltage, lifetime, and luminescence efficiency.

[0140] Device Comparative Example 1: Prepare an organic electroluminescent device according to the same method as in Device Example 1, and the structure of the green light doping compound in the light-emitting layer is as follows:

[0141] ​

[0142] Device Comparative Example 2: An organic electroluminescent device was prepared in the same manner as in Device Example 1, and the structure of the green-light doped compound in the light-emitting layer was as follows:

[0143]

[0144] Device Comparative Example 3: An organic electroluminescent device was prepared in the same manner as in Device Example 1, and the structure of the green-light doped compound in the light-emitting layer was as follows:

[0145]

[0146] Device Comparative Example 4: An organic electroluminescent device was prepared in the same manner as in Device Example 1, and the structure of the green-light doped compound in the light-emitting layer was as follows:

[0147]

[0148] Device Example 2: Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-10.

[0149] Device Example 3 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-21.

[0150] Device Example 4 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-50.

[0151] Device Example 5 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-99.

[0152] Device Example 6 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-145.

[0153] Device Example 7 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-172.

[0154] Device Example 8 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-205.

[0155] Device Example 9 Referring to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-239.

[0156] Device Example 10 According to the method of Device Example 1 above, the only difference is that the doping material Z-1 is replaced with Z-306.

[0157] Device Embodiment 11 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-385.

[0158] Device Embodiment 12 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-404.

[0159] Device Embodiment 13 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-444.

[0160] Device Embodiment 14 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-467.

[0161] Device Embodiment 15 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-501.

[0162] Device Embodiment 16 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-533.

[0163] Device Embodiment 17 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-567.

[0164] Device Embodiment 18 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-590.

[0165] Device Embodiment 19 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-605.

[0166] Device Embodiment 20 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-634.

[0167] Device Embodiment 21 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-658.

[0168] Device Embodiment 22 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-690.

[0169] Device Embodiment 23 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-707.

[0170] Device Embodiment 24 Referring to the method of Device Embodiment 1 above, the only difference is that the doping material Z-1 is replaced with Z-754.

[0171] Device Example 25 The method of the above Device Example 1 is the same, except that the doping material Z-1 is replaced with Z-802.

[0172] Device Example 26 The method of the above Device Example 1 is the same, except that the doping material Z-1 is replaced with Z-848.

[0173] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained from the above device examples and device comparative examples were characterized at a brightness of 15,000 (nits), and the test results are shown in Table 1 below.

[0174] Table 1

[0175]

[0176]

[0177] As can be seen from Table 1:

[0178] 1. By comparing Comparative Compounds 1, 2, 3, and 4 with the organometallic compounds Z-1, Z-10, Z-21, Z-50, Z-99, Z-145, Z-172, Z-205, Z-239, Z-316, Z-385, Z-404, Z-444, Z-467, Z-501, Z-533, Z-567, Z-590, Z-605, Z-634, Z-658, Z-690, Z-707, Z-754, Z-802, and Z-848 of the present application, it can be seen that by changing the combination of substituents on 2-(dibenz[b,d]furan-4-yl)-4-isopropylpyridine, increasing phenyl, fluorine-substituted biphenyl, branched alkyl, substituted or unsubstituted cycloalkyl, and introducing deuterated groups, using the "heavy atom effect", the spin-orbit coupling effect of the luminescent molecule is enhanced, the ability of electron intersystem crossing in the molecule is increased, which is beneficial to the generation of phosphorescence, enhancing its quantum efficiency, and generating organometallic compounds, improving the intermolecular spatial configuration, having good spatial torsion ability, effectively regulating the HOMO and LUMO energy levels, thus avoiding carrier migration. After using it as a specific doping material for the light-emitting layer and applying it to an organic electroluminescent device, the driving voltage of the device is reduced, and the luminous efficiency and lifetime of the device are improved.

[0179] 2. Compared with the organic electroluminescent devices prepared using the compounds of Comparative Examples 1-4 as the light-emitting layer doping materials, the organic electroluminescent devices prepared using the compounds provided by the present invention as the light-emitting layer doping materials have a significantly lower driving voltage and a significantly higher luminous efficiency. The above examples only list the effect data of the devices made of a part of the structural formulas, which is a representative sampling test. Judging from the experimental data, the overall data does not differ much and can represent the effects of other unlisted structures.

[0180] The applicant declares that the present invention illustrates the organometallic compound, its preparation method and the organic electroluminescent device of the present invention through the above embodiments. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent substitution of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. An organometallic compound, characterized in that, The organometallic compound has a structure represented by General Formula I: Wherein, R1, R2, R3, R4, R5 and R6 are each independently selected from hydrogen, -D, -T, -CN, -F, -CD3, -CF3, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C1-C40 alkoxy, trimethylgermyl or trimethylsilyl, or a combination of any one or at least two of them; R7, R8, R9, R 10 , R 11 , R 12 , R 13 and R 14 each independently selected from hydrogen, -D, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, unsubstituted C1-C6 alkyl, C1-C6 alkyl fully or partially substituted with deuterium, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C1-C40 alkoxy, trimethylgermanium or trimethylsilicon, or any combination of any one or at least two thereof; Ra is Rb is R 15 、R 16 、R 17 、R 18 、R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 and R 26 each independently selected from hydrogen, -D, -T, -CN, -F, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C2-C6 alkynyl, substituted or unsubstituted C2-C15 heterocyclic group, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C1-C40 alkoxy, trimethylgermane, trimethylsilane, or any combination of any one or at least two thereof; Rc is selected from hydrogen, -D (deuterium), -T (tritium), -CN, -F, substituted or unsubstituted C1-C6 alkyl, substituted or unsubstituted C3-C24 heteroaryl, substituted or unsubstituted C3-C40 cycloalkyl, substituted or unsubstituted C2-C40 alkenyl or alkynyl, substituted or unsubstituted C2-C40 heterocyclic group, substituted or unsubstituted C1-C40 alkoxy, trimethylgermyl or trimethylsilyl; The hydrogen in the groups in Formula I may be unsubstituted by deuterium or partially or fully substituted by deuterium; D represents deuterium and T represents tritium.

2. The organometallic compound according to claim 1, wherein R1, R2, R3, R4, R5 and R6 are each independently selected from hydrogen, -D, -CN, -F, -CF3, methyl, ethyl, propyl, butyl, neopentyl, cyclopentyl, cyclohexyl, phenyl, trimethylsilyl, trimethylgermyl or the following groups: any one or a combination of at least two thereof, * represents the attachment site of the group.

3. The organometallic compound according to claim 1, wherein R7, R8, R9, R 10 , R 11 , R 12 , R 13 and R 14 each independently selected from hydrogen, -D, -CN, -F, -CD3, -CF3, methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, phenyl, deuterated phenyl, isobutyl, trimethylsilyl, trimethylgermyl, any one or a combination of at least two of C1-C6 alkyl groups that are completely or partially substituted with deuterium.

4. The organometallic compound according to claim 1, wherein R 15 、R 16 、R 17 、R 18 、R 19 、R 20 、R 21 、R 22 、R 23 、R 24 、R 25 and R 26 are each independently selected from -F, -CN, -D, methyl, ethyl, propyl, butyl, pentyl, cyclopropyl, cyclopentyl, phenyl, dibenzofuranyl, dibenzothiophenyl, biphenyl, naphthyl, phenyl substituted with C1-C6 alkyl, biphenyl substituted with C1-C6 alkyl, trimethylgermanium, trimethylsilicon or any one or a combination of at least two thereof, where * represents the attachment site of the group.

5. The organometallic compound according to claim 1, wherein The substituents on the substituted groups are selected from -F, -CN, -D, -CD3, methyl, ethyl, propyl, butyl, pentyl, phenyl, naphthyl, dibenzofuranyl, dibenzothiophenyl, biphenyl, cyclopentyl, cyclohexyl, cyclopropyl, trimethylgermyl, trimethylsilyl or tetramethylcyclohexyl, or a combination of any one or at least two of them.

6. The organometallic compound according to claim 1, wherein, The organometallic compound is preferably selected from one of the following compounds:

7. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes an anode, a cathode, and an organic material layer disposed between the anode and the cathode, and the organic material layer includes at least one of the organometallic compounds described in any one of Claims 1-6.

8. The organic electroluminescent device according to claim 7, wherein The organic material layer includes a light-emitting layer, the light-emitting layer includes a host material and a doping material, and the doping material includes at least one of the organometallic compounds described in any one of Claims 1-6.

9. The organic electroluminescent device according to claim 7, wherein, The organic material layer further includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer or an electron injection layer.

10. The organic electroluminescent device according to claim 7, characterized in that, The organic electroluminescent device includes an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode disposed in sequence.

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