Organometallic compound and organic electroluminescent device containing same

Abstract

The invention belongs to the field of organic photoelectric materials, and discloses an organic metal compound and an organic electroluminescent device containing the same. After the organic metal compound provided by the invention is used as a specific doping material of a luminous layer and is applied to the organic electroluminescent device, the driving voltage of the device is reduced, so that 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 field of organic optoelectronic materials, and particularly relates to an organometallic compound and an organic electroluminescent device comprising the same. Background Art

[0002] Organic electronic devices include, but are not limited to, organic light-emitting diodes (OLEDs), organic field-effect transistors (O-FETs), 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] The emission color of OLEDs can be achieved through the design of the structure of the light-emitting material. OLEDs can include one or more light-emitting layers to achieve the desired spectrum.

[0004] As early as 1963, Pope et al. first discovered the electroluminescence phenomenon of single crystal anthracene of organic compounds. In 1987, Eastman Kodak Company in the United States made an amorphous device by evaporating organic small molecules, reducing the driving voltage to within 20V. OLED is a hole and electron double-injection type light-emitting device that directly converts electrical energy into the light energy of organic semiconductor material molecules. Compared with traditional display devices such as CRT, LCD, and PDP, OLED combines all the advantages of existing displays and has its own unique advantages. It has high brightness, high contrast, high definition, wide viewing angle, wide color gamut, etc. to achieve high-quality images, and also has characteristics such as ultra-thin, ultra-light, low driving voltage, low power consumption, and wide temperature range to meet the requirements of portable devices for being lightweight, power-saving, and suitable for outdoor operation. Moreover, self-luminescence, high luminous efficiency, short response time, transparency, flexibility, etc. are the unique characteristics of OLED displays. Therefore, OLED has been widely studied, developed, and used.

[0005] In 1998, Forrest et al. from Princeton University in the United States found through research that by doping phosphorescent dye platinum octaethylporphyrin into the host light-emitting material, a light-emitting device with an external quantum efficiency of 4% and an internal quantum efficiency of up to 23% was prepared, thus opening up a new field of phosphorescent electroluminescence. In the following years, the research on organic electroluminescence phosphorescence has developed rapidly. As phosphorescent materials, noble metal complexes make full use of singlet and triplet excitons. Compared with fluorescent materials that only utilize singlet excitons, the effective utilization of triplet excitons with a proportion as high as 75% enables the internal quantum efficiency of PhOLEDs based on phosphorescent materials to reach 100%. Therefore, the research on highly efficient phosphorescent organic electroluminescent devices provides an important impetus for the development of the flat panel and portable display industries.

[0006] Therefore, how to develop a high-performance phosphorescent material that enables organic electroluminescent 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 skilled in the art. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention discloses and provides an organometallic compound and an organic electroluminescent device containing the same.

[0008] To achieve the above object, the following technical solutions are adopted:

[0009] The first object of the present invention is to provide an organometallic compound having a structure represented by General Formula I:

[0010]

[0011] Wherein, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 are each independently selected from hydrogen, -D, -CD 3 , -CD 2 , -T, -CN, -F, -CT 3 , -CF 3 , -CH 2 F, -CHF 2 , a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C3-C24 heteroaryl group, a substituted or unsubstituted C2-C6 alkynyl group, a substituted or unsubstituted methoxy group, trimethylgermane, trimethylsilane, or any combination of any one or at least two of them;

[0012] R 5 , R 6 are each independently selected from hydrogen, -D, -T, -CN, -F, -CH 3 , -CT 3 , -CF 3 , -CH 2 F, -CHF, or any combination of any one or at least two of them;

[0013] R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 and R 16Each independently selected from hydrogen, -D, -T, -CN, -F, -CT 3 , -CF 3 , -CH 2 F, -CHF 2 , a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C3-C15 cycloalkyl group, a substituted or unsubstituted C1-C6 alkoxy group, trimethylsilane, trimethylgermane, or any combination of any one or at least two thereof;

[0014] Ra is selected from -D, -T, -CN, -F, -CT 3 , -CF 3 , -CH 2 F, -CHF 2 , a substituted or unsubstituted C1-C6 alkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C3-C24 heteroaryl group, a substituted or unsubstituted C2-C6 alkynyl group, a substituted or unsubstituted methoxy group, trimethylgermane, trimethylsilane, or any combination of any one or at least two thereof.

[0015] Preferably, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 each independently selected from hydrogen, -D, -T, -CN, -F, -CT 3 , -CF 3 , -CH 2 F, -CHF 2 , -CD 3 , -CD 2 , methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, cyclohexyl, phenyl, biphenyl, deuterated butyl, deuterated pentyl, deuterated phenyl, deuterated biphenyl, fluorine-substituted phenyl, trimethylsilane, trimethylgermane, or any combination of any one or at least two thereof.

[0016] Preferably, R 5 and R 6 each independently selected from -CH 3 , -F, or a combination of the two.

[0017] Preferably, R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 and R 16Each independently selected from hydrogen, -D, -T, -CN, -F, -CT 3 , -CF 3 , -CH 2 F, -CHF 2 , -CD 3 , -CD 2 , methyl, ethyl, propyl, butyl, pentyl, phenyl, biphenyl, trimethylgermane, trimethylsilane, or a combination of any one or at least two thereof.

[0018] Preferably, Ra is selected from -D, -CN, -F, -CF 3 , -CHF 2 , methyl, ethyl, propyl, butyl, phenyl, biphenyl, tert-butylbenzene, fluorine-substituted phenyl, trimethylsilane, trimethylgermane, or a combination of any one or at least two thereof.

[0019] Furthermore, the term "substituted" means substituted by one, two or more substituents selected from the following: hydrogen, deuterium, halogen group, cyano group, trifluoromethyl group, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, sec-butyl group, 1-methylbutyl group, 1-ethylbutyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 4-methyl-2-pentyl group, 3,3-dimethylbutyl group, 2-ethylbutyl group, 1-methylhexyl group, phenyl group, naphthyl group, anthryl group, phenanthryl group, thiophenyl group, furyl group, pyrrolyl group, benzothiophenyl group, benzofuryl group, pyridyl group, indolyl group, cyclopentyl group, cyclohexyl group, adamantane, or a substituent formed by connecting two or more of the above-mentioned substituents, or having no substituent.

[0020] Moreover, the hydrogen atoms in the above groups are either substituted by deuterium or not substituted by deuterium.

[0021] Preferably, the organometallic compound is preferably selected from one of the following structures, but not limited thereto:

[0022]

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[0090]

[0091] The second object of the present invention is to provide a method for preparing the above-mentioned organometallic compound. In the present invention, the preparation process of the organometallic compound of formula I is as follows:

[0092]

[0093] wherein, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 and Ra are as defined above and will not be elaborated here.

[0094] The preparation operation is as follows:

[0095] Under nitrogen protection, ligand of formula V, IrC1 3 ·3H 2 O are put into the reaction system, a mixed solution of ethylene glycol monoethyl ether and pure water is added, and the mixture is refluxed at 120 °C for 36 hours under nitrogen protection to obtain intermediate of formula IV;

[0096] Silver trifluoromethanesulfonate was added to the intermediate of formula Ⅳ, and then dichloromethane and methanol were added to the system. The mixture was refluxed at 25 °C for 36 hours under nitrogen protection to obtain the intermediate of formula Ⅲ;

[0097] The ligand of formula Ⅱ was added to the intermediate of formula Ⅲ, and then absolute ethanol was added to the system. The mixture was refluxed at 70 °C for 36 hours under nitrogen protection to obtain the organometallic compound shown in formula I.

[0098] The third technical object of the present invention is to provide 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.

[0099] Preferably, 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 above-mentioned organometallic compounds.

[0100] 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.

[0101] 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 disposed in sequence.

[0102] Generally speaking, 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.

[0103] 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, waterproofness, and transparency. In addition, a thin film transistor (TFT) can also be provided on the substrate for display use.

[0104] 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, indium tin oxide (ITO), indium zinc oxide (IZO), tin dioxide (SnO 2) Oxide transparent conductive materials such as zinc oxide (ZnO) and any combination thereof. In addition, the anode material can also be selected from materials that contribute to hole injection and their combinations other than the listed anode materials, including known materials suitable for making anodes. When the first electrode serves as the 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 cathode materials listed above, the cathode material can also be a material that contributes to electron injection and its combination, including known materials suitable for making cathodes.

[0105] 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, and polymers, as well as their combinations. 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).

[0106] The materials for the hole transport layer can be selected from, but are 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.

[0107]

[0108]

[0109] 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 use one or more of the above compounds HT-1 to HT-30, or one or more of the following compounds HI-1 to HI-3; it can also use one or more of the above compounds HT-1 to HT-30 doped with one or more of the following compounds HI-1 to HI-3:

[0110]

[0111] The OLED organic material layer may further include an electron transport region between the light-emitting layer and the cathode. The electron transport region may 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 may 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).

[0112] In one aspect of the present application, the electron transport layer material may be selected from, but not limited to, one or a combination of more than one of the following listed ET-1 to ET-36:

[0113]

[0114]

[0115]

[0116] The device may further include an electron injection layer between the electron transport layer and the cathode. The electron injection layer material includes, but is not limited to, one or a combination of more than one of the following listed:

[0117] LiF, NaCl, CsF, Li 2 O, Cs 2 CO 3 , BaO, Na, Li, Ca.

[0118] Compared with the prior art, the present invention has the following beneficial effects:

[0119] By changing the combination of substituents on 2-(8-([1,1'-biphenyl]-4-yl)-9,9-difluoro-7-(trifluoromethyl)-9H-fluoren-1-yl)pyridine, adding branched-chain alkyl groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted cycloalkyl groups to generate an organometallic compound, the intermolecular spatial configuration is improved, and it has good spatial torsion ability, thereby 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, thereby avoiding carrier migration, and the driving voltage is significantly reduced, and the luminous efficiency and lifespan are significantly improved. Description of the Drawings

[0120] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0121] Figure 1 1H NMR spectrum of compound Z-1 prepared in Example 1. Detailed implementation manners

[0122] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention and the related drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0123] The embodiments of the present invention specifically disclose an organometallic compound, a preparation method, and an organic electroluminescent device.

[0124] The features and performance of the present invention will be further described in detail below in conjunction with specific embodiments.

[0125] Example 1

[0126] This example provides an organometallic compound Z-1, and the specific synthesis steps are as follows:

[0127]

[0128] Under nitrogen protection, take compound 2-(bromodifluoromethyl)-1,3-dichlorobenzene (CAS: 3020760-44-2) (180 mmol) and KoAc (540 mmol) and put them into the reaction system. Add 1000 ml of 1,4-dioxane. Under nitrogen protection, add tris(dibenzylideneacetone)dipalladium (3.6 mmol) and X-Phos (14.4 mmol). Add bis(pinacolato)diborane (CAS: 73183-34-3) (180 mmol) in three batches every 1 hour. After adding, reflux at 100 °C for 24 h under nitrogen protection, and then cool to 25 °C. After the reaction is cooled, concentrate under reduced pressure. Column chromatography (200-300 mesh, 450 g) the crude product to remove impurities. The eluent is EA:PE = 1:10. Rotate the receiving solution until no liquid flows out, and dry it under vacuum to obtain the shown compound intermediate 1 (63.24 g, yield 96%), and its HPLC purity is greater than 99.5%. Mass spectrum: calculated value is 366.12.

[0129] 1 HNMR(400MHz, chloroform-d) δ7.53(dd,1H),7.42(dd,1H),7.22(t,1H),1.24(s,12H).

[0130]

[0131] Under nitrogen protection, take intermediate 1 (180 mmol) and anhydrous potassium carbonate (540 mmol) and place them in the reaction system. Add 1000 mL of toluene, 500 mL of absolute ethanol, and 500 mL of pure water. Under nitrogen protection, add Pd(PPh 3 ) 4 (1.5 mmol). Add 2,6-dichloro-3-(trifluoromethyl)phenylboronic acid (CAS: 1027059-21-7) (180 mmol) in three batches every 1 hour. After addition, 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 with anhydrous magnesium sulfate, concentrate under reduced pressure, and subject the crude product to column chromatography (200 - 300 mesh, 420 g) to remove impurities. The eluent is EA:PE = 1:20. Rotate the collected solution until no liquid flows out, and dry it under vacuum to obtain the indicated compound intermediate 2 (17.46 g, yield 21%), with an HPLC purity greater than 99.5%. Mass spectrum: calculated value is 462.06.

[0132] 1 H NMR (400 MHz, chloroform-d) δ 8.81 (s, 2H), 7.62 - 7.53 (m, 2H), 7.46 (dd, 1H), 7.33 (dd, 1H), 7.34 - 7.27 (m, 1H).

[0133]

[0134] Under nitrogen protection, take intermediate 2 (180 mmol) and anhydrous potassium carbonate (540 mmol) and place them in the reaction system. Add 1000 mL of toluene, 500 mL of absolute ethanol, and 500 mL of pure water. Under nitrogen protection, add Pd(PPh 3 ) 4 (1.5 mmol). After addition, reflux at 100 °C for 48 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 with anhydrous magnesium sulfate, concentrate under reduced pressure, and subject the crude product to column chromatography (200 - 300 mesh, 500 g) to remove impurities. The eluent is EA:PE = 1:15. Rotate the collected solution until no liquid flows out, and dry it under vacuum to obtain the indicated compound intermediate 3 (17.43 g, yield 27%), with an HPLC purity greater than 99.5%. Mass spectrum: calculated value is 338.09.

[0135] 1 HNMR (400 MHz, chloroform-d) δ 7.90 - 7.81 (m, 2H), 7.64 (d, 1H), 7.44 (t, 1H), 7.41 (dd, 1H).

[0136]

[0137] Under nitrogen protection, take intermediate 3 (180 mmol) and anhydrous potassium carbonate (540 mmol) and put them into the reaction system. Add 1000 mL of toluene, 500 mL of absolute ethanol, and 500 mL of pure water. Under nitrogen protection, add Pd(PPh 3 ) 4 (1.5 mmol). Add 2-pyridineboronic acid (CAS: 197958-29-5) (180 mmol) in three batches every 1 hour. After addition, 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 with anhydrous magnesium sulfate, concentrate under reduced pressure. Subject the crude product to column chromatography (200 - 300 mesh, 400 g) to remove impurities. The eluent is EA:PE = 1:20. Rotate the receiving solution until no liquid flows out, and dry it under vacuum to obtain the indicated compound intermediate 4 (37.04 g, yield 54%), and its HPLC purity is greater than 99.5%. Mass spectrum: calculated value is 381.16.

[0138] 1 H NMR (400 MHz, chloroform-d) δ 8.68 (dd, 1H), 7.91 - 7.79 (m, 4H), 7.75 - 7.68 (m, 1H), 7.61 (d, 1H), 7.52 - 7.45 (m, 1H), 7.25 (ddd, 1H).

[0139]

[0140] Under nitrogen protection, take intermediate 4 (180 mmol) and anhydrous potassium carbonate (540 mmol) and put them into the reaction system. Add 1000 mL of toluene, 500 mL of absolute ethanol, and 500 mL of pure water. Under nitrogen protection, add Pd(PPh 3 ) 4 (1.5 mmol). Add 4-biphenylboronic acid (CAS: 5122-94-1) (180 mmol) in three batches every 1 hour. After addition, 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 with anhydrous magnesium sulfate, concentrate under reduced pressure. Subject the crude product to column chromatography (200 - 300 mesh, 500 g) to remove impurities. The eluent is EA:PE = 1:10. Rotate the receiving solution until no liquid flows out, and dry it under vacuum to obtain Formula II-1 (85.35 g, yield 95%), and its HPLC purity is greater than 99.5%. Mass spectrum: calculated value is 499.27.

[0141] 11H NMR (400 MHz, chloroform-d) δ 8.64 (dd, 1H), 7.93 - 7.85 (m, 2H), 7.89 - 7.78 (m, 2H), 7.75 - 7.67 (m, 3H), 7.65 - 7.58 (m, 2H), 7.60 - 7.53 (m, 3H), 7.50 (dd, 1H), 7.44 (ddt, 2H), 7.43 - 7.35 (m, 1H), 7.25 (ddd, 1H).

[0142]

[0143] Under a nitrogen protection system, weigh out ligand V-1 (50 mmol) (CAS: 27012-22-2) and IrCl 3 ·3H 2 O (20 mmol) and place them into the reaction system. Add a mixed solution of 420 mL of ethylene glycol monoethyl ether and 140 mL of pure water. Reflux at 120 °C for 36 hours under nitrogen protection, then cool to room temperature. A precipitate forms. Filter the precipitate by suction, and wash and dry it successively with water, absolute ethanol, and petroleum ether to obtain 9.93 g of the bridged ligand formula IV-1 with a yield of 88%.

[0144]

[0145] Under a nitrogen protection system, weigh out intermediate formula IV-1 (20 mmol), add silver trifluoromethanesulfonate (44 mmol), then add 600 mL of dichloromethane and 200 mL of methanol to the system. Reflux at 25 °C for 36 hours under nitrogen protection, then cool to room temperature. Concentrate the filtrate of column chromatography until a solid precipitates to obtain iridium complex formula III-1 (15.13 g, yield 95%).

[0146]

[0147] Under a nitrogen protection system, weigh out III-1 (20 mmol), add formula II-1 (44 mmol), then add 150 mL of 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 and silica gel column chromatography. Concentrate the filtrate until a solid precipitates to obtain the final compound Z-1 (9.45 g, yield 46%). HPLC purity: greater than 99.5%; Mass spectrum: calculated value is 1027.39.

[0148] 11H NMR (400 MHz, chloroform-d) δ 8.68 (dd, 1H), 8.47 (dq, 1H), 8.36 (d, 1H), 8.16 (dd, 1H), 8.07 (dd, 1H), 8.00 - 7.92 (m, 2H), 7.82 (d, 1H), 7.75 (td, 1H), 7.72 - 7.65 (m, 4H), 7.65 - 7.59 (m, 2H), 7.61 - 7.54 (m, 3H), 7.47 - 7.38 (m, 2H), 7.41 - 7.31 (m, 5H), 7.31 - 7.22 (m, 2H), 7.24 - 7.15 (m, 3H), 7.12 (d, 1H), 2.42 (d, 3H), 2.25 (s, 3H).

[0149] The 1H NMR spectrum of the compound Z-1 prepared in Example 1 is as Figure 1 shown.

[0150] 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.

[0151] Device Example 1: Preparation of an organic electroluminescent device using the organometallic compound of formula Z-1

[0152] The ITO glass substrate with a coating thickness of was washed twice in distilled water, ultrasonically washed for 30 minutes. After the distilled water washing was completed, it was ultrasonically washed in solvents such as isopropanol, acetone, and methanol in sequence and then dried, transferred to a plasma cleaner, and the above substrate was washed for 10 minutes and then sent to an evaporation coater.

[0153] First, a hole injection layer of HI-01 with a thickness of was evaporated on ITO (anode), then a hole transport layer of HT-01 with a thickness of was evaporated on the hole injection layer. Immediately thereafter, a light-emitting layer of the host material 4,4'-N,N'-dicarbazole biphenyl ("CBP") and the dopant material compound of formula Z-1 in a weight ratio of 90:10 was evaporated. Then, an electron transport layer of ET-01 with a thickness of was evaporated on the light-emitting layer. Immediately thereafter, an electron injection layer material Liq with a thickness of was evaporated on the electron transport layer. Finally, a cathode material Al with a thickness of was evaporated on the electron injection layer, and an organic electroluminescent device could be obtained. The performance and luminescence characteristics of the obtained device were tested. The measurement was carried out using a KEITHLEY 2400 source measurement unit and a CS-2000 spectro-radiance meter to evaluate the driving voltage, lifetime, and luminescence efficiency.

[0154] For the obtained device, the luminescence characteristics were tested. The measurement was carried out using a KEITHLEY 2400 source measurement unit and a CS-2000 spectro-radiance meter to evaluate the driving voltage, lifetime, and luminescence efficiency.

[0155] Device Comparative Example 1:

[0156] An organic electroluminescent device was prepared by the same method as in Device Example 1, and the structure of the green light-doped compound in the light-emitting layer was as follows:

[0157] Device Comparative Example 2:

[0158] An organic electroluminescent device was prepared by the same method as in Device Example 1, and the structure of the green light-doped compound in the light-emitting layer was as follows:

[0159] Device Comparative Example 3:

[0160] An organic electroluminescent device was prepared by the same method as in Device Example 1, and the structure of the green light-doped compound in the light-emitting layer was as follows:

[0161] Device Comparative Example 4:

[0162] An organic electroluminescent device was prepared by the same method as in Device Example 1, and the structure of the green light-doped compound in the light-emitting layer was as follows:

[0163] Device Examples 2 - Device Examples 30:

[0164] Referring to the method of Device Example 1 above, the only difference was that the doping material Z-1 was replaced with Z-8, Z-16, Z-50, Z-98, Z-144, Z-168, Z-200, Z-234, Z-303, Z-365, Z-405, Z-432, Z-466, Z-499, Z-532, Z-566, Z-588, Z-600, Z-634, Z-659, Z-688, Z-706, Z-755, Z-800, Z-840, Z-870, Z-888, Z-998, Z-1022 respectively.

[0165] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained in the above Device Examples and Device Comparative Examples were characterized at a brightness of 15000 (nits), and the test results are shown in Table 1 below:

[0166] Table 1

[0167]

[0168]

[0169] As can be seen from Table 1:

[0170] 1. By comparing Comparative Examples 1, 2, 3, and 4 with the organometallic compounds Z-1, Z-8, Z-16, Z-50, Z-98, Z-144, Z-168, Z-200, Z-234, Z-303, Z-365, Z-405, Z-432, Z-466, Z-499, Z-532, Z-566, Z-588, Z-600, Z-634, Z-659, Z-688, Z-706, Z-755, Z-800, Z-840, Z-870, Z-888, Z-998, and Z-1022 of the present application, it can be seen that by changing the combination of substituents on 2-(8-([1,1'-biphenyl]-4-yl)-9,9-difluoro-7-(trifluoromethyl)-9H-fluoren-1-yl)pyridine and adding branched alkyl groups, substituted or unsubstituted aryl groups, and substituted or unsubstituted cycloalkyl groups to generate organometallic compounds, the intermolecular spatial configuration is improved, with better spatial torsion ability, effectively regulating the HOMO and LUMO energy levels, thereby avoiding carrier migration. When used as a specific doping material for the light-emitting layer and applied to an organic electroluminescent device, the driving voltage of the device is reduced, thereby avoiding carrier migration. When the compound of the present application is used as a doping material for the light-emitting layer, the organic electroluminescent device prepared has a significantly lower driving voltage compared to the organic electroluminescent device prepared in the comparative example, and the luminous efficiency and lifespan are significantly improved.

[0171] 2. Compared with the organic electroluminescent devices prepared using the compounds provided in the present application as the doping material for the light-emitting layer, the organic electroluminescent devices prepared using Comparative Examples 1-4 as the doping material for the light-emitting layer have a significantly lower driving voltage and a significantly enhanced luminous efficiency.

[0172] It should be noted that the above embodiments only list the effect data of the devices made from a part of the structural formulas. This is a representative sampling test. Judging from the experimental data, the overall data do not differ much and can represent the effects of other unlisted structures.

[0173] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organometallic compound, characterized in that The structure of the organometallic compound is shown in Formula I: Wherein, R1, R2, R3, R4, R7 and R8 are each independently selected from any one or a combination of at least two of hydrogen, -D, -CD3, -CD2, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, 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 methoxy, trimethylgermanium, trimethylsilyl; R5 and R6 are each independently selected from any one or a combination of at least two of hydrogen, -D, -T, -CN, -F, -CH3, -CT3, -CF3, -CH2F, -CHF; R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 and R 16 Each is independently selected from any one or a combination of at least two of hydrogen, -D, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, substituted or unsubstituted C1-C20 alkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C15 cycloalkyl, substituted or unsubstituted C1-C6 alkoxy, trimethylsilyl, and trimethylgermanium; Ra is selected from any one or a combination of at least two of -D, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, 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 methoxy, trimethylgermanium, and trimethylsilyl.

2. The organometallic compound according to claim 1, characterized in that R5 and R6 are each independently selected from -CH3, -F or a combination of the two.

3. The organometallic compound according to claim 1, characterized in that R1, R2, R3, R4, R7 and R8 are each independently selected from hydrogen, -D, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, -CD3, -CD2, methyl, ethyl, propyl, butyl, pentyl, cyclopentyl, cyclohexyl, phenyl, biphenyl, deuterated butyl, deuterated pentyl, deuterated phenyl, deuterated biphenyl, fluorine-substituted phenyl, trimethylsilicon, trimethylgermanium, any one or a combination of at least two thereof.

4. The organometallic compound according to claim 1, characterized in that R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 and R 16 Each is independently selected from any one or a combination of at least two of hydrogen, -D, -T, -CN, -F, -CT3, -CF3, -CH2F, -CHF2, -CD3, -CD2, methyl, ethyl, propyl, butyl, pentyl, phenyl, biphenyl, trimethylgermanium, and trimethylsilyl.

5. The organometallic compound according to claim 1, characterized in that Ra is selected from any one of -D, -CN, -F, -CF3, -CHF2, methyl, ethyl, propyl, butyl, phenyl, biphenyl, tert-butylbenzene, fluorine-substituted phenyl, trimethylsilyl, trimethylgermanium, or a combination of at least two thereof.

6. The organometallic compound according to any one of claims 1 to 5, characterized in that The term "substituted" means substituted by one, two or more substituents selected from the group consisting of hydrogen, deuterium, halogen, cyano, trifluoromethyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, phenyl, naphthyl, anthracenyl, phenanthrenyl, thienyl, furanyl, pyrrolyl, benzothienyl, benzofuranyl, pyridyl, indolyl, cyclopentanyl, cyclohexanyl, adamantane, or substituted by two or more of the substituents shown above connected to each other, or having no substituents; The hydrogen atoms in the groups may be substituted with deuterium or not.

7. The organometallic compound according to claim 1, characterized in that The organometallic compound is selected from one of the following structures, but is not limited thereto:

8. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises an anode, a cathode and an organic material layer disposed between the anode and the cathode; the organic material layer comprises at least one of the organic metal compounds as claimed in claim 1.

9. The organic electroluminescent device according to claim 8, characterized in that: The organic electroluminescent device comprises a light-emitting layer, and the light-emitting layer comprises the organic metal compound.

10. The organic electroluminescent device according to claim 9, characterized in that: The light-emitting layer of the organic electroluminescent device comprises a main material and a doping material; the doping material comprises at least one of the organic metal compounds, and the mixing mass ratio of the main material to the doping material is 90:10 to 99.5:0.5.

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