An organic electroluminescent material and an organic electroluminescent device

Abstract

The application provides an organic electroluminescent material and an organic electroluminescent device, and belongs to the field of organic electroluminescent materials.The organic electroluminescent material has a structure shown in formula I.The organic electroluminescent material has a low refractive index, and is used as a luminescent auxiliary material in a thicker layer of a double-layer luminescent auxiliary material, so that the organic electroluminescent device prepared by matching the low-refractive-film layer of formula I with a high-refractive luminescent auxiliary material can better play a light collecting role, the light emitted from the device can be emitted in a specific wavelength, the emission spectrum can be narrowed, the luminescent intensity of the light in the specific wavelength is enhanced, the light loss is reduced, the luminescent efficiency of the device is improved, meanwhile, a lower driving voltage and a longer device service life are ensured.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, specifically relating to an organic electroluminescent material and an organic electroluminescent device. Background Technology

[0002] Organic electroluminescence refers to the phenomenon of converting electrical energy into light energy using organic materials. OLED (Organic Light Emitting Diode) technology, with its significant advantages such as self-emissive properties, high contrast, wide viewing angle, and fast response speed, has been widely and deeply applied in many fields, including smartphones, televisions, displays, and lighting. Organic light-emitting elements utilizing the organic light-emitting phenomenon typically have a structure containing an anode and a cathode, as well as an organic layer located between them. To address lifetime and efficiency issues, a light-emitting auxiliary layer (multilayer hole transport layer) is usually added between the hole transport layer and the light-emitting layer.

[0003] The light-emitting auxiliary layer enables holes transferred from the anode to move smoothly to the light-emitting layer and blocks electrons transferred from the cathode, thus confining electrons within the light-emitting layer. This reduces the potential barrier between the hole transport layer and the light-emitting layer, lowers the driving voltage of the organic electroluminescent device, and further increases the utilization rate of holes, thereby improving the luminous efficiency and lifetime of the device.

[0004] Currently, there are few materials capable of forming a light-emitting auxiliary layer with excellent device performance. In particular, improvements in OLED lifetime and driving voltage are not significant. Material performance often requires extensive tuning and structural modifications to achieve ideal device performance. Device performance is the result of the combined effects of various factors, such as device structure, material refractive index, HOMO, LUMO, triplet energy levels, deposition morphology, free radical activity, carrier balance, deposition temperature, mobility, capacitance, color shift, and testing conditions (temperature, brightness, current density). Material manufacturers aim to improve the performance of organic electroluminescent devices by enhancing certain performance indicators.

[0005] Currently, there are very limited materials available for constructing light-emitting auxiliary layers that can impart excellent performance to devices, especially in improving the lifespan and luminous efficiency of OLEDs, where the effects are not significant. As panel manufacturers continue to raise their requirements for material performance, the development of high-performance organic functional materials has become particularly urgent. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an organic electroluminescent material and an organic electroluminescent device. Compound I of the present invention uses Ar2-substituted 9-phenyl-9-methylfluorene as its core (Ar2 is selected from deuterated or unsubstituted phenyl, naphthyl, and biphenyl), linked to an aromatic amino group. One of the aromatic amino side chains contains adamantane, cyclohexyl, or a C1-C6 alkyl group (especially tert-butyl or tert-pentyl), resulting in a compound of formula I with a low refractive index. This low-refractive-index compound of formula I, used as a light-emitting auxiliary material, is applied to the thicker layer of a bilayer light-emitting auxiliary material. This allows light emitted from within the device to pass through the low-refractive-index film of formula I. The organic electroluminescent device prepared by combining this low-refractive-index film with the high-refractive-index light-emitting auxiliary material can better concentrate light, emitting specific wavelengths of light emitted from the device. This narrows the emission spectrum, enhances the luminous intensity of specific wavelengths, reduces light loss, and improves the device's luminous efficiency, while ensuring a low driving voltage and a long device lifespan.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] On one hand, the present invention provides an organic electroluminescent material having the structure shown in Formula I:

[0009]

[0010] Where D represents deuterium;

[0011] n is an integer selected from 0, 1, 2, 3, 4, and 5;

[0012] R is selected from the following groups, whether substituted with deuterium or not: methyl, ethyl, propyl, tert-butyl;

[0013] L1 and L2 are each independently selected from the linking bond, and are aryl groups with or without substitution of C6-C24;

[0014] L3 is selected from substituted or unsubstituted C6-C24 aryl groups;

[0015] R1 is selected from adamantyl, substituted or unsubstituted C3-C24 cycloalkyl, and deuterated or unsubstituted C1-C10 alkyl.

[0016] m is an integer selected from 1, 2, 3, 4, and 5;

[0017] Ar1 is selected from hydrogen, adamantyl, substituted or unsubstituted C6-C24 aryl, substituted or unsubstituted C3-C24 cycloalkyl, and substituted or unsubstituted C1-C10 alkyl.

[0018] Ar2 is selected from the following groups, whether substituted or unsubstituted with deuterium: phenyl, naphthyl, biphenyl;

[0019] The substituents in the substituted group are selected from the following groups that are deuterated or unsubstituted: hydrogen, phenyl, biphenyl, naphthyl, methyl, ethyl, tert-butyl, and tert-pentyl.

[0020] further,

[0021] L1 and L2 are each independently selected from the following groups that are deuterated or unsubstituted, which are linked by the following groups: phenyl, methylphenyl, naphthyl, biphenyl, terphenyl;

[0022] L3 is selected from the following groups, whether deuterated or unsubstituted: phenyl, methylphenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl;

[0023] R1 is selected from the following groups, whether deuterated or unsubstituted: adamantyl, cyclohexyl, methyl, ethyl, propyl, tert-butyl, tert-amyl;

[0024] Ar1 is independently selected from hydrogen, and the following groups are either deuterated or unsubstituted: phenyl, naphthyl, biphenyl, adamantyl, cyclohexyl, methyl, ethyl, tert-butyl, tert-pentyl, 9,9-dimethylfluorenyl;

[0025] Furthermore, the organic electroluminescent material has any one of the structures of formula I-1 to I-12:

[0026]

[0027] L1 is selected from the connection key;

[0028] n is selected from 0 or 5;

[0029] L2 and L3 are each independently selected from the following groups that are deuterated or unsubstituted, which are linked by the following groups: phenyl, methylphenyl, naphthyl, biphenyl, terphenyl;

[0030] Ar1 is selected from hydrogen, and the following groups substituted or unsubstituted with deuterium: phenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl, tert-butyl, methyl;

[0031] Ar2 is selected from phenyl groups that are either deuterated or unsubstituted.

[0032] Going further,

[0033] Selected from the following groups:

[0034]

[0035] The wavy lines represent the connection sites of the functional groups.

[0036] The phrase "replaced by deuterium" refers to being partially or completely replaced by deuterium.

[0037] Preferably, the organic electroluminescent material is any one of the following compounds, but not limited to:

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] .

[0047] Synthetic route

[0048] The series of palladium-catalyzed coupling reactions in this invention utilize the activity differences of halogens I>Br>Cl, and control the reaction sites by controlling the reaction conditions. The reactions are purified by column chromatography or silica gel funnel to remove byproducts and obtain the target compound.

[0049] For raw materials that are not publicly available, those skilled in the art can synthesize them using classic Suzuki coupling reactions, Buchwald–Hartwig coupling reactions, butyllithium reactions, and apply them to this invention.

[0050] The following are common knowledge references:

[0051] Organometallic Chemistry (6th Edition), Robert H. Crabtree, published by East China University of Science and Technology Press, Shanghai, September 00, 2017, ISBN: 978-7-5628-5111-0, page 388.

[0052] Organic Chemistry and Optoelectronic Materials Experiment Tutorial, Chen Runfeng, Publisher: Southeast University Press, Publication Date: 2019-11-00, ISBN: 9787564184230, Page 174.

[0053] Synthesis route of Formula I:

[0054] The synthesis method can be carried out by referring to one or more of the following steps:

[0055]

[0056] B' is selected from —B(OH)2 or ;

[0057] Hal1, Hal2, and Hal3 are selected from chlorine, bromine, or iodine;

[0058] D, n, m, Ar1, Ar2, L1, L2, L3, R, R1 are defined in the same way as general formula I;

[0059] Under nitrogen atmosphere, reactant Ia (1.1-1.2 eq) was dissolved in a mixed solution of toluene, ethanol and water, and reactant Ib was dissolved in a mixed solution of toluene, ethanol and water. The reactant Ib (1.0 eq) solution was slowly added to the reactant Ia solution, and potassium carbonate (2-3 eq) and tetrakis(triphenylphosphine)palladium (0.01-0.05 eq) were added. The mixture was stirred until homogeneous, heated to 70℃-90℃, and refluxed for 8-12 h. The mixture was then purified by column chromatography to obtain intermediate Ic.

[0060] Under nitrogen atmosphere, intermediate Ic (1.0 eq) was dissolved in toluene, and reactant Id (1.1-1.3 eq) was dissolved in toluene and slowly added to the intermediate Ic solution. Tris(dibenzylacetone)dipalladium (0.01-0.05 eq), tri-tert-butylphosphine (0.02-0.1 eq), and sodium tert-butyloxide (2-3 eq) were added to the solution. The temperature was raised to 90℃-110℃, and the reaction was carried out for 8-12 h. The solution was purified by column chromatography to obtain intermediate Ie.

[0061] Under nitrogen atmosphere, intermediate Ie (1.0 eq) was dissolved in toluene, and reactant If (1.1-1.3 eq) was dissolved in toluene and slowly added to the intermediate Ie solution. Tris(dibenzylacetone)dipalladium (0.01-0.05 eq), tri-tert-butylphosphine (0.02-0.1 eq), and sodium tert-butyloxide (2-3 eq) were added to the solution. The temperature was raised to 90℃-110℃, and the reaction was carried out for 8-12 h. The solution was purified by column chromatography to obtain chemical formula I.

[0062] On the other hand, the present invention provides an organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode and an organic layer disposed between the anode and the cathode, the organic layer comprising a light-emitting auxiliary layer, the light-emitting auxiliary layer comprising the organic electroluminescent material as described above.

[0063] Preferably, the organic electroluminescent device further includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. The structure of the organic light-emitting element is not limited to this, and may include fewer or more organic layers.

[0064] The compound of Formula I prepared in this invention is used as a light-emitting auxiliary layer material.

[0065] Preferably, the light-emitting auxiliary layer comprises multiple light-emitting auxiliary layers.

[0066] Preferably, the organic layer includes a hole transport layer and a light-emitting auxiliary layer. The light-emitting auxiliary layer includes a first light-emitting auxiliary layer and a second light-emitting auxiliary layer. The first light-emitting auxiliary layer includes the organic electroluminescent material as described above, and the first light-emitting auxiliary layer is located between the hole transport layer and the second light-emitting auxiliary layer.

[0067] Regarding the compound represented by Formula I, in the manufacture of organic light-emitting elements, an organic layer is formed using vacuum evaporation or solution coating. Solution coating methods include spin coating, dip coating, blade coating, inkjet printing, screen printing, spray coating, and roll coating, but are not limited to these.

[0068] Depending on the materials used, the organic light-emitting element of the present invention is classified into top-emitting type, bottom-emitting type, or bidirectional-emitting type.

[0069] The devices of this invention are used in organic electroluminescent devices, including but not limited to flat panel displays, computer monitors, medical monitors, televisions, billboards, lamps for internal or external lighting and / or signals, head-up displays, fully transparent or partially transparent displays, flexible displays, laser printers, telephones, mobile phones, tablets, photo albums, personal digital assistants (PDAs), wearable devices, laptops, digital cameras, camcorders, viewfinders, microdisplays, 3D displays, virtual reality or augmented reality displays, vehicles, video walls including multiple displays tiled together, theater or stadium screens, phototherapy devices, and signs.

[0070] As the anode material, a material with a high work function is selected to facilitate the injection of holes into the organic layer. Specific examples of anode materials that can be used in this invention include vanadium, chromium, copper, zinc, gold or their alloys; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); combinations of metals and oxides such as ZnO:Al or SnO2:Sb; and conductive polymers such as polypyrrole and polyaniline.

[0071] The hole injection layer is selected as a p-doped hole injection layer, which means a hole injection layer doped with p-doped agents. P-doped agents are materials that can impart p-type semiconductor characteristics. P-type semiconductor characteristics refer to the characteristics of injecting or transporting holes at the HOMO energy level, that is, the characteristics of materials with high hole conductivity.

[0072] Hole transport material is a material capable of receiving holes from the anode or hole injection layer and transporting the holes to the light-emitting layer, and the hole transport material is a material with high hole mobility. The hole transport material is selected from aryl amine derivatives, conductive polymers, and block copolymers that simultaneously contain conjugated and non-conjugated parts.

[0073] An auxiliary light-emitting layer (multilayer hole transport layer) is added between the hole transport layer and the light-emitting layer. The auxiliary light-emitting layer primarily assists the hole transport layer and is therefore sometimes referred to as a second hole transport layer. This layer allows holes transferred from the anode to smoothly move to the light-emitting layer and blocks electrons transferred from the cathode, confining them within the light-emitting layer. This reduces the potential barrier between the hole transport layer and the light-emitting layer, lowers the driving voltage of the organic light-emitting device, and further increases hole utilization, thereby improving the device's luminous efficiency and lifetime.

[0074] The luminescent material in the luminescent layer is a material that can receive holes and electrons from the hole transport layer and the electron transport layer respectively, and combine them to emit light in the visible light region. The material with high quantum efficiency for fluorescence or phosphorescence is selected.

[0075] The light-emitting layer comprises a host material and a dopant material, with a mass ratio of host material to dopant material of 90-99.5:0.5-10.

[0076] The main materials are aromatic fused-ring derivatives or heterocyclic compounds. Specifically, aromatic fused-ring derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentane derivatives, phenanthrene compounds, or fluoranthene compounds, while heterocyclic compounds include carbazole derivatives, dibenzofuran derivatives, or pyrimidine derivatives.

[0077] The dopant materials of this invention include fluorescent doping and phosphorescent doping, specifically selected from aromatic amine derivatives, styrylamine compounds, boron complexes, fluoranthene compounds, or metal complexes.

[0078] The electron transport layer can promote electron transport. The electron transport material is a material that can effectively receive electrons from the cathode and transport them to the light-emitting layer. Specifically, it is selected from materials with high electron mobility. The electron transport layer includes an electron buffer layer, a hole blocking layer, and an electron transport layer.

[0079] The electron injection layer facilitates electron injection and has the ability to transport electrons, preventing excitons generated in the light-emitting layer from migrating to the hole injection layer. Materials for the electron injection layer include, but are not limited to, oxazoles, oxadiazoles, triazoles, imidazoles, perylenetetracarboxylic acids, fluorenemethane, anthrones and their derivatives, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, ytterbium, or their alloys, metal complexes, or nitrogen-containing 5-membered ring derivatives.

[0080] The cathode is selected from materials with a small work function to facilitate electron injection into an organic material layer with a thickness between 0.5 and 5 nm. Specifically, the cathode materials include magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead or their alloys: LiF / Al or LiO2 / Al, Mg / Ag multilayer structures.

[0081] Apart from Formula I included in the light-emitting auxiliary layer disclosed in this invention, there are no special restrictions on the materials of other layers in OLED devices. Existing hole injection materials, hole transport materials, hole transport auxiliary materials, dopant materials, hole blocking layer materials, electron transport layer materials, and electron injection materials can be used.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] The compound of the present invention has a core of 9-phenyl-9-methylfluorene substituted with Ar2 (Ar2 is selected from phenyl, naphthyl, biphenyl substituted or unsubstituted), which is linked to an aromatic amino group, wherein one of the aromatic amino side chains contains adamantane, cyclohexyl, C1-C6 alkyl (especially tert-butyl, tert-pentyl), and the resulting compound of formula I has a low refractive index.

[0084] The low-refractive-index compound of Formula I of this invention is used as a light-emitting auxiliary material in the thicker layer of a double-layer light-emitting auxiliary material. This allows the light emitted from the device to pass through the low-refractive-index film of Formula I. The organic electroluminescent device prepared by combining the low-refractive-index film of Formula I with the high-refractive-index light-emitting auxiliary material can better concentrate the light, emit specific wavelengths of light emitted from the device, narrow the emission spectrum, enhance the luminous intensity of specific wavelengths of light, reduce light loss, improve the luminous efficiency of the device, and at the same time ensure a low driving voltage and a long device life. Attached Figure Description

[0085] Figure 1 This is the 1H NMR spectrum of compound 1. Detailed Implementation

[0086] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0087] Example 1: Synthesis of Compound 1

[0088]

[0089] CAS: Reactant 1-a: 3070970-02-1;

[0090] CAS: Reactant 1-b: 1459-48-9;

[0091] CAS: Reactant 1-d: 98974-71-1.

[0092] Under nitrogen atmosphere, reactant 1-a (1.0 eq) and reactant 1-b (1.2 eq) were dissolved in toluene and slowly added to intermediate Ic solution. Tris(dibenzylacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.02 eq), and sodium tert-butyloxide (2.2 eq) were added to the solution. The mixture was heated to 100 °C and reacted for 8 h. The solution was purified by column chromatography to obtain intermediate 1-c (yield: 83.4%).

[0093] Under nitrogen atmosphere, intermediate 1-c (1.0 eq) was dissolved in toluene, and reactant 1-d (1.3 eq) was dissolved in toluene and slowly added to the intermediate 1-c solution. Tris(dibenzylacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.02 eq), and sodium tert-butyloxide (2.4 eq) were added. The mixture was heated to 100 °C and reacted for 8 h. The solution was purified by column chromatography to obtain chemical formula 1 (yield: 79.6%, MS (ESI, m / Z): [M+H)). + = 709.52).

[0094] Characterization:

[0095] The proton NMR spectrum of compound 1 is as follows: Figure 1 As shown.

[0096] HPLC purity: >99.8%.

[0097] Elemental analysis:

[0098] Theoretical values: C, 91.35; H, 6.67; N, 1.97

[0099] Test values: C, 91.16; H, 6.84; N, 2.06.

[0100] Example 2: Synthesis of Compound 385

[0101]

[0102] CAS: Reactant 1-385: 2606032-01-1.

[0103] Under nitrogen atmosphere, reactant 385-a (1.0 eq) and reactant 385-b (1.2 eq) were dissolved in toluene and slowly added to the intermediate 385-c solution. Tris(dibenzylacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.03 eq), and sodium tert-butyloxide (2.4 eq) were added to the solution. The mixture was heated to 100 °C and reacted for 8 h. The solution was purified by column chromatography to obtain intermediate 385-c (yield: 81.9%).

[0104] Under nitrogen atmosphere, intermediate 385-c (1.0 eq) was dissolved in toluene, and reactant 385-d (1.2 eq) was dissolved in toluene and slowly added to the intermediate 385-c solution. Tris(dibenzylacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.03 eq), and sodium tert-butyloxide (2.3 eq) were added. The mixture was heated to 100 °C and reacted for 8 h. The solution was purified by column chromatography to obtain chemical formula 385 (yield: 77.5%, MS (ESI, m / Z): [M+H)). += 709.44).

[0105] Characterization:

[0106] HPLC purity: >99.8%.

[0107] Elemental analysis:

[0108] Theoretical values: C, 91.35; H, 6.67; N, 1.97

[0109] Test values: C, 91.22; H, 6.79; N, 2.02.

[0110] Additionally, it should be noted that other compounds in this application can be obtained by referring to the synthesis methods listed in the examples above, so they will not be listed one by one here. The mass spectrometer used for mass spectrometry in this application is a Waters XEVO TQD, which is low-precision and uses an ESI source.

[0111] Refractive index test

[0112] Preparation of monolayer films for optical property evaluation

[0113] Compound I (see the compounds of this invention in Table 1) and comparative compounds 1-24 were respectively deposited on silicon substrates with a film thickness of 50 nm. The refractive index n and extinction coefficient k at a wavelength of 530 nm were measured. The structures of comparative compounds 1-24 are shown below, and the measurement data are shown in Table 1.

[0114]

[0115]

[0116]

[0117] Table 1. Test results of refractive index n and extinction coefficient k

[0118]

[0119]

[0120] Under a refractive index test at 530 nm, the refractive index of compound I of the present invention is between 1.62 and 1.66, while that of the comparative compound is between 1.75 and 1.78. Under similar structures, the refractive index is reduced by about 0.09-0.16, and the extinction coefficient k value is almost 0 in each color gamut, which does not affect the luminescence of the luminescent layer.

[0121] The compound of the present invention has a core of 9-phenyl-9-methylfluorene substituted with Ar2 (Ar2 is selected from phenyl, naphthyl, biphenyl substituted or unsubstituted), which is linked to an aromatic amino group, wherein one of the aromatic amino side chains contains adamantane, cyclohexyl, C1-C6 alkyl (especially tert-butyl, tert-pentyl), and the resulting compound of formula I has a low refractive index.

[0122] The low-refractive-index compound of Formula I of this invention is used as a light-emitting auxiliary material in the thicker layer of a double-layer light-emitting auxiliary material. This allows the light emitted from the device to pass through the low-refractive-index film of Formula I. The organic electroluminescent device prepared by combining the low-refractive-index film of Formula I with the high-refractive-index light-emitting auxiliary material can better concentrate the light, emit specific wavelengths of light emitted from the device, narrow the emission spectrum, enhance the luminous intensity of specific wavelengths of light, reduce light loss, improve the luminous efficiency of the device, and at the same time ensure a low driving voltage and a long device life.

[0123] The following examples illustrate the application of the low refractive index material of Formula I provided in this application in organic electroluminescent devices.

[0124] Fabrication of green organic light-emitting diodes:

[0125] a. ITO anode: An ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 14nm / 150nm / 14nm is washed twice in distilled water, ultrasonically cleaned for 30 minutes, then washed twice more in distilled water, ultrasonically cleaned for 10 minutes. After washing, it is transferred to a spin dryer for spin drying, and finally baked in a vacuum oven at 220℃ for 2 hours. After baking, it is cooled down before use. Using this substrate as the anode, the device process is carried out using a vapor deposition machine, and other functional layers are sequentially vapor deposited on it.

[0126] b. HIL (hole injection layer): Hole injection layer materials HT1 and P-dopant are vacuum evaporated at a evaporation rate of 1 Å / s, with a evaporation rate ratio of 95:5 for HT1 and P-dopant, and a thickness of 10 nm.

[0127] c. HTL (hole transport layer): 130 nm of HT1 is vacuum-deposited on the hole injection layer at a deposition rate of 1.0 Å / s as a hole transport layer.

[0128] d. Light-emitting auxiliary layer-1: The compound of formula I provided in the embodiments of the present invention is vacuum-deposited on the hole transport layer at a deposition rate of 1.0 Å / s for 40 nm as light-emitting auxiliary layer-1.

[0129] e. Light-emitting auxiliary layer-2: Prime-2 of 5 nm is vacuum-deposited on the light-emitting auxiliary layer-1 at a deposition rate of 1.0 Å / s as light-emitting auxiliary layer-2;

[0130] f. EML (Emitting Layer): Then, on the above-mentioned emitting auxiliary layer, a host material (Host-1 and Host-2) and a dopant material (Dopant-G) with a thickness of 40 nm are vacuum-deposited at a deposition rate of 1 Å / s as the emitting layer. Host-1 and Host-2 are co-deposited with the dopant material as dual host materials, with a ratio of 50%:50%. The deposition rate ratio of the host material to the dopant is 90:10.

[0131] g. HBL (hole blocking layer): HB-1 with a thickness of 5.0 nm was vacuum-deposited at a deposition rate of 0.5 Å / s as a hole blocking layer.

[0132] h. ETL (Electron Transport Layer): ET-1 and Liq, with a thickness of 30 nm, were vacuum-deposited at a deposition rate of 1 Å / s as the electron transport layer. The deposition rate ratio of ET-1 to Liq was 50:50.

[0133] i. EIL (Electron Injection Layer): A 1.0 nm Yb film is deposited at a deposition rate of 0.5 Å / s to form an electron injection layer.

[0134] j. Cathode: Magnesium and silver are deposited at a deposition rate of 1 Å / s for 13 nm, with a deposition rate ratio of 1:9, to form the cathode.

[0135] k. Optical extraction layer: CPL-1 with a thickness of 60 nm is vacuum-deposited on the cathode at a deposition rate of 1 Å / s as the optical extraction layer.

[0136] 1. Encapsulate the vapor-deposited substrate. First, use a coating equipment to coat the cleaned cover plate with UV adhesive. Then, move the coated cover plate to the lamination section, place the vapor-deposited substrate on the top of the cover plate, and finally, laminate the substrate and cover plate together using a bonding equipment, while simultaneously curing the UV adhesive by light.

[0137] The structural formulas of the raw materials required for each of the above layers are shown below:

[0138] .

[0139] Application Examples 1-141

[0140] Organic electroluminescent devices of Application Examples 1-141 were prepared according to the above-described method for preparing organic electroluminescent devices, except that the compound of Formula I in Application Example 1 was replaced with the corresponding compound (refer to the compounds involved in Table 2) to form a light-emitting auxiliary layer.

[0141] Comparative Examples 1-24

[0142] Organic electroluminescent devices of Comparative Examples 1-24 were prepared according to the preparation method of Application Example 1 of the above-mentioned organic electroluminescent device, except that Formula I in Application Example 1 was replaced with the corresponding comparative compound (refer to the comparative compounds 1-24 involved in Table 2) to form a light-emitting auxiliary layer.

[0143] The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained in Application Example 1 and Comparative Examples 1-24 were characterized at a brightness of 15000 nits. The test results are shown in Table 2 below.

[0144] Table 2. Results of luminous properties test (luminance value 15000 nits)

[0145]

[0146]

[0147] The compound of formula I of this invention uses Ar2-substituted 9-phenyl-9-methylfluorene as its core (Ar2 is selected from deuterated or unsubstituted: phenyl, naphthyl, biphenyl), linked to an aromatic amino group, wherein one of the aromatic amino side chains contains adamantane, cyclohexyl, or a C1-C6 alkyl group (especially tert-butyl or tert-pentyl). The resulting compound of formula I has a low refractive index. The interaction between the low-refractive-index compound and the high-refractive-index compound of this invention makes the focusing effect of the device more significant, and the device performance is improved in terms of efficiency and lifetime.

[0148] In the prior art, the main difference between comparative compounds 1-7 and Formula I of the present invention is that there is no phenyl group at the 9-position of fluorene; among them, comparative compound 3 and compound 408 of the present invention, and comparative compound 7 and compound 427 of the present invention are parallel comparative compounds; 9-phenyl-9-methylfluorene introduces a rigid aromatic ring at the 9-position, which can form an excited dimer and achieve strong charge resonance stability, thereby improving electron transport efficiency and contributing to the improvement of luminescence efficiency.

[0149] The main difference between Comparative Compounds 8-13 and Formula I of the present invention is that 9-phenyl-9-methylfluorene is not substituted with Ar2. Among them, Comparative Compound 9 is parallel to Compound 78 of the present invention, Comparative Compound 10 is parallel to Compound 7 of the present invention, Comparative Compound 11 is parallel to Compound 11 of the present invention, Comparative Compound 12 is parallel to Compound 79 of the present invention, and Comparative Compound 13 is parallel to Compound 87 of the present invention. The Ar2 substituents work together to make the compounds less prone to crystallization in the device, resulting in better light emission characteristics.

[0150] Under the same device conditions, the compounds provided by this invention exhibit higher luminous efficiency and longer lifetime.

[0151] The main difference between Comparative Compounds 14-20 and Formula I of the present invention is that the aromatic amino side chain does not contain one of adamantane, cyclohexyl, or C1-C6 alkyl groups; wherein, Comparative Compound 14 is parallel comparative compound to Compound 7 of the present invention, Comparative Compound 16 is parallel comparative compound to Compound 100 of the present invention, Comparative Compound 17 is parallel comparative compound to Compound 181 of the present invention, Comparative Compound 18 is parallel comparative compound to Compound 11 of the present invention, and Comparative Compound 19 is parallel comparative compound to Compound 57 of the present invention; wherein, the adamantane, cyclohexyl, or C1-C6 alkyl groups in the side chain are not conjugated, which reduces the refractive index of the compound.

[0152] Comparative compounds 21-24 are similar to Formula I of the present invention, but differ in their core and side chains.

[0153] As shown in Table 2, the driving voltage of the comparative compounds is between 3.5-3.6V, the efficiency is between 166-168 cd / A, and the lifetime is between 820-840h. The compound of Formula I in this invention has higher luminous efficiency, longer lifetime, and lower driving voltage.

[0154] When the side chain of the compound of the present invention contains adamantane, the efficiency is significantly improved, generally ranging from 178 to 181 cd / A, and the lifetime is between 900 and 925 h; when the side chain contains alkyl groups (especially tert-butyl and tert-pentyl), the lifetime is between 960 and 980 h, which is significantly improved.

[0155] This invention illustrates the organic electroluminescent material and organic electroluminescent device through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of the raw materials used in this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. An organic electroluminescent material, characterized in that, The organic electroluminescent material has the structure shown in Formula I: ； Where D represents deuterium; n is an integer selected from 0, 1, 2, 3, 4, and 5; R is selected from the following groups, whether substituted with deuterium or not: methyl, ethyl, propyl, tert-butyl; L1 is selected from a linker bond or a phenyl group; L2 is selected from the following groups, whether substituted with deuterium or not: phenyl, methylphenyl, naphthyl, biphenyl, terphenyl; L3 is selected from the following groups, whether deuterated or unsubstituted: phenyl, methylphenyl, naphthyl, biphenyl; R1 is selected from the following groups, whether deuterated or unsubstituted: adamantyl, cyclohexyl, tert-butyl, tert-pentyl; Ar1 is independently selected from hydrogen, and the following groups are either deuterated or unsubstituted: phenyl, naphthyl, biphenyl, adamantyl, cyclohexyl, methyl, ethyl, tert-butyl, tert-pentyl, 9,9-dimethylfluorenyl; m is an integer selected from 1, 2, 3, 4, and 5; Ar2 is selected from phenyl groups that are either deuterated or unsubstituted.

2. The organic electroluminescent material according to claim 1, characterized in that, The organic electroluminescent material has any one of the structures of formula I-1 to I-12: ； L1 is selected from the connection key; n is selected from 0 or 5; L2 is selected from the following groups, whether substituted with deuterium or not: phenyl, naphthyl, biphenyl, terphenyl; L3 is selected from the following groups, whether deuterated or unsubstituted: phenyl, naphthyl, biphenyl; Ar1 is selected from hydrogen, and the following groups substituted or unsubstituted with deuterium: phenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl, tert-butyl, methyl.

3. The organic electroluminescent material according to claim 1, characterized in that, Selected from the following groups: ； ； ； The wavy lines represent the connection sites of the functional groups.

4. An organic electroluminescent material, characterized in that, The organic electroluminescent material is any one of the following compounds: 。 5. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes an anode, a cathode, and an organic layer disposed between the anode and the cathode. The organic layer includes a light-emitting auxiliary layer, which includes the organic electroluminescent material according to any one of claims 1-4.

6. The organic electroluminescent device according to claim 5, characterized in that, The light-emitting auxiliary layer comprises multiple light-emitting auxiliary layers.

7. The organic electroluminescent device according to claim 5, characterized in that, The organic layer includes a hole transport layer and a light-emitting auxiliary layer. The light-emitting auxiliary layer includes a first light-emitting auxiliary layer and a second light-emitting auxiliary layer. The first light-emitting auxiliary layer includes the organic electroluminescent material according to any one of claims 1-4. The first light-emitting auxiliary layer is located between the hole transport layer and the second light-emitting auxiliary layer.

8. The organic electroluminescent device according to claim 7, characterized in that, The organic electroluminescent device further includes at least one of a hole injection layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer.

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