Organic electroluminescent material, preparation method thereof and organic electroluminescent device

Abstract

The invention relates to the technical field of luminescent materials, and discloses an organic electroluminescent material, a preparation method thereof and an organic electroluminescent device. The structure of the organic electroluminescent material is shown as a formula I: # imgabs0 #. The organic electroluminescent material compound provided by the invention can be used as a functional layer of an organic electroluminescent device and has the advantage of ultra-long service life performance, and meanwhile, the driving voltage and the luminous efficiency are also improved.

Description

Technical Field

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

[0002] Due to a series of remarkable advantages such as self-luminescence characteristics, high contrast ratio, wide viewing angle, and fast response speed, OLED technology has been widely and deeply applied in many fields such as smart phones, televisions, displays, and lighting.

[0003] In the existing system, the hole transport material has a relatively low highest occupied molecular orbital (HOMO) value, which causes exciton diffusion, resulting in interface luminescence and uneven charge distribution in the light-emitting layer, thereby reducing the color purity, luminous efficiency of the device, and shortening the service life. To solve the problems of device life and efficiency, a light-emitting auxiliary layer (multi-layer hole transport layer) is usually introduced between the hole transport layer and the light-emitting layer. The main function of the light-emitting auxiliary layer is to assist the hole transport layer, also known as the second hole transport layer. It can promote the smooth transport of holes injected from the anode to the light-emitting layer, while blocking electrons from the cathode and confining the electrons in the light-emitting layer. This not only reduces the potential barrier between the hole transport layer and the light-emitting layer, enabling the driving voltage of the organic electroluminescent device to be reduced, but also further improves the utilization rate of holes, thereby effectively improving the luminous efficiency and service life of the device.

[0004] Currently, the materials that can be used to construct the light-emitting auxiliary layer and endow the device with excellent performance are very limited. Especially in terms of improving the life and luminous efficiency of OLEDs, the effect is not significant. With the continuous improvement of the requirements for material performance by panel manufacturing enterprises, the development of high-performance organic functional materials has become particularly urgent. Summary of the Invention

[0005] In view of this, aiming at the deficiencies of the prior art, the present invention discloses an organic electroluminescent material, a preparation method thereof, and an organic electroluminescent device.

[0006] It should be noted that the compounds of the present invention simultaneously have: (1) the 1,2 positions of dibenzofuran form a fused ring with a phenyl group, (2) naphthobenzofuran and are connected in an ortho position on the benzene ring, (3) is connected to a specific aryl group; (4) the structure must contain deuterium; the compounds disclosed by the present invention have the advantages of ultra-long life performance, and at the same time, the driving voltage and luminous efficiency have also been improved.

[0007] To achieve the above object, the following technical solutions are adopted:

[0008] The first object of the present invention is to provide an organic electroluminescent material having the structure shown in Formula I:

[0009]

[0010] Among them,

[0011] R1 - R 23 contains at least one deuterium;

[0012] R1 - R 13 are each independently selected from hydrogen and deuterium;

[0013] R 14 -R 23 are each independently selected from hydrogen, deuterium, and group A; adjacent Rs 14 -R 23 can also be connected to form a benzene ring substituted or unsubstituted by deuterium or group A;

[0014] Group A is selected from the following groups substituted or unsubstituted by deuterium: phenyl, naphthyl, biphenyl, naphthyl substituted by benzene.

[0015] Furthermore, any one of Rs 14 -R 18 is selected from group A, and the rest are selected from hydrogen or deuterium; any one of Rs 19 -R 23 is selected from group A, and the rest are selected from hydrogen or deuterium.

[0016] Most preferably, formula I has the following structure:

[0017]

[0018] In the present invention, the substituent position is defined as

[0019] In the present invention, the organic electroluminescent material compound is any one of the following structures, but not limited thereto:

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031] The second object of the present invention is to provide a preparation method of the above-mentioned organic electroluminescent material, and the specific operation is as follows:

[0032] Step 1:

[0033] Under N2 protection, the reactant a-I (1.0 eq), the reactant b-I (1-1.2 eq), [1,1'-bis(diphenylphosphino)ferrocene] dichloropalladium(II) (Pd(dppf)Cl2) (0.02-0.08 eq), and potassium carbonate (K2CO3) (2.0-2.5 eq) are respectively added to a mixed solvent of toluene, ethanol, and water (2-4:1:1). The temperature is raised to 80-90 °C, and the reaction is carried out for 2-6 h. After cooling to room temperature, it is purified by column chromatography, and the obtained solid is dried to obtain the intermediate c-I;

[0034] Step 2:

[0035] Under N2 protection, the intermediate c-I (1.0 eq), the reactant d-I (1.2 eq), sodium tert-butoxide (NaO(t-Bu)2) (2.0-3.0 eq), 2-cyclohexylphosphino-2,4,6-triisopropylbiphenyl (X-Phos) (0.02-0.05 eq), and tris(dibenzylideneacetone) dipalladium (Pd(dba)2) (0.02-0.05 eq) are added to toluene. The temperature is raised to 90-100 °C, and the reaction is carried out for 2-8 h. After cooling to room temperature, it is purified by column chromatography, and the obtained solid is dried to obtain Formula-I;

[0036] Synthesis route

[0037]

[0038] The third object of the present invention is to provide an organic electroluminescent device, and the organic electroluminescent device includes the above-mentioned organic electroluminescent material.

[0039] Furthermore, the organic electroluminescent device includes an organic layer; the organic layer contains the above-mentioned organic electroluminescent material.

[0040] Even further, the organic electroluminescent material is used as the light-emitting auxiliary layer material of the organic electroluminescent device.

[0041] Compared with the prior art, the present invention provides an organic electroluminescent material, a preparation method thereof, and an organic electroluminescent device, which have the following excellent effects:

[0042] The compound disclosed in the present invention has the advantages of ultra-long lifetime performance. At the same time, the driving voltage and luminous efficiency are also improved. In formula I of the present invention, (1) the 1,2 positions of dibenzofuran form a fused ring with a phenyl group, which can shorten the conjugated plane, increase the triplet energy level (T1) of the blue light-emitting auxiliary layer, and improve the exciton blocking ability; (2) naphthobenzofuran and are connected to the benzene ring in an ortho manner, which makes the molecular configuration extremely distorted, shortens the conjugated length, increases the energy gap, enables the blue light-emitting auxiliary material to have a shallower LUMO energy level while ensuring a suitable HOMO energy level, improves the electron blocking ability, increases the number of exciton recombinations, reduces exciton polaron annihilation, improves the efficiency and lifetime, and further increases the triplet energy level, playing a role in exciton blocking. (3) Connecting specific groups such as benzene and biphenyl can effectively reduce the HOMO energy level to a suitable position, enabling holes to be smoothly injected into the light-emitting layer. (4) There must be deuterium in the structure. The blue light-emitting auxiliary material is greatly impacted by excitons and is prone to bond breakage. After deuteration, the bond dissociation energy is enhanced, improving the lifetime. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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, other drawings can be obtained according to the provided drawings without creative efforts.

[0044] Figure 1 1H NMR spectrum of Compound 13. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention and the relevant 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 fall within the scope of the present invention.

[0046] The present invention specifically discloses an organic electroluminescent material, a preparation method thereof, and an organic electroluminescent device.

[0047] The characteristics and performance of the present invention will be further described in detail below in conjunction with specific examples.

[0048] Example 1:

[0049]

[0050] CAS: Reactant b'-13: 186491-73-6

[0051] CAS: Reactant a-13: 1668553-50-1

[0052] CAS: Reactant d-13: 897671-74-8

[0053] Under N2 protection, Reactant b'-13 (1.0 eq), silver carbonate (Ag2CO3) (0.2 eq), 2-dicyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl (S-Phos) (0.5 eq), and potassium carbonate (K2CO3) (1.0 eq) were added to deuterium oxide (D2O) (10.0 eq) and toluene. The temperature was raised to 95 °C and the reaction was carried out for 24 h. After cooling to room temperature, the product was purified by column chromatography, and the obtained solid was dried to obtain Reactant b-13 (yield: 94.2%);

[0054] Under N2 protection, Reactant a-I (1.0 eq), Reactant b-13 (1.2 eq), dichlorobis (diphenylphosphino) ferrocene palladium (II) (Pd(dppf)Cl2) (0.04 eq), and potassium carbonate (K2CO3) (2.0 eq) were respectively added to a mixed solvent of toluene, ethanol, and water (4:1:1). The temperature was raised to 80 °C and the reaction was carried out for 3 h. After cooling to room temperature, the product was purified by column chromatography, and the obtained solid was dried to obtain Intermediate c-13 (yield: 83.5%);

[0055] Under N2 protection, Intermediate c-13 (1.0 eq), Reactant d-13 (1.2 eq), sodium tert-butoxide (NaO(t-Bu)) (2.0 eq), 2-cyclohexyl-2,4,6-triisopropylbiphenyl (X-Phos) (0.02 eq), and bis (dibenzylideneacetone) palladium (Pd(dba)2) (0.02 eq) were added to toluene. The temperature was raised to 95 °C and the reaction was carried out for 2 h. After cooling to room temperature, the product was purified by column chromatography, and the obtained solid was dried to obtain Compound 13 (yield: 78.8%, measured value MS(ESI, m / z): [M+H]+ = 717.38).

[0056] The yields in the above steps are the fractional yields of the corresponding steps.

[0057] Characterization:

[0058] HPLC purity: >99.7%.

[0059] Elemental analysis: Test values: C, 89.82; H, 6.03; N, 2.03; O, 2.18

[0060] Figure 1 1H NMR spectrum of Compound 13.

[0061] Example 2:

[0062]

[0063] CAS: Reactant d-181: 2055815-15-9

[0064] Under N2 protection, reactant a-181 (1.0 eq), reactant b-181 (1.2 eq), [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (Pd(dppf)Cl2) (0.04 eq), and potassium carbonate (K2CO3) (2.0 eq) were separately added to a mixed solvent of toluene, ethanol, and water (4:1:1). The temperature was raised to 80 °C and the reaction was carried out for 3 h. After cooling to room temperature, it was purified by column chromatography. The obtained solid was dried to obtain intermediate c-181 (yield: 86.7%);

[0065] Under N2 protection, intermediate c-181 (1.0 eq), reactant d-181 (1.2 eq), sodium tert-butoxide (NaO(t-Bu)) (2.0 eq), 2-cyclohexyl-2,4,6-triisopropylbiphenyl (X-Phos) (0.02 eq), and tris(dibenzylideneacetone)dipalladium (Pd(dba)2) (0.02 eq) were added to toluene. The temperature was raised to 95 °C and the reaction was carried out for 2 h. After cooling to room temperature, it was purified by column chromatography. The obtained solid was dried to obtain Compound 181 (yield: 74.1%, test value MS(ESI, m / Z): [M+H]+ = 735.56).

[0066] The yields in the above steps are the fractional yields of the corresponding steps.

[0067] Characterization:

[0068] HPLC purity: >99.6%.

[0069] Elemental analysis: Test values: C, 87.60; H, 8.23; N, 2.06; O, 2.15

[0070] Other compounds of this application can be obtained by referring to the preparation methods listed above, so they are not listed one by one here. The mass spectrometer model is Waters XEVO TQD, with low precision and ESI source test.

[0071] The structure of an organic electroluminescent device is flexible and includes multiple organic layers such as a hole injection layer and a hole transport layer. The number of layers can be increased or decreased according to requirements. The compound of formula I prepared in the present invention is used as a material for a light-emitting auxiliary layer.

[0072] When manufacturing an organic light-emitting element, there are various methods for the compound of formula I to form an organic layer. The vacuum evaporation method can accurately control the film thickness and composition; the solution coating method includes spin coating, dip coating, blade coating, inkjet printing, screen printing, spraying, roll coating, etc. Spin coating is suitable for small-area and high-precision films; inkjet and screen printing are suitable for large-scale patterned production; dip coating, blade coating, spraying, and roll coating perform well in large-area and low-cost coating.

[0073] Organic light-emitting elements are classified into top-emitting, bottom-emitting, and bi-directional emitting types according to materials. The top-emitting type is suitable for upward lighting or display scenarios; the bottom-emitting type performs well in applications where it is closely combined with the underlying structure and light needs to be obtained from below; the bi-directional emitting type can be used for all-round lighting or display occasions. Its applications are extensive, covering many fields such as flat panel displays, computer monitors, medical monitors, lighting fixtures, wearable devices, virtual reality displays, etc.

[0074] The anode material needs to be selected from those with a large work function, such as metals and their alloys like vanadium, chromium, etc., which have good conductivity and a high work function. Metal oxides such as zinc oxide and indium oxide have transparency and a high work function and are suitable for transparent electrodes. Combinations of metals and oxides such as ZnO:A1 and conductive polymers such as polypyrrole and polyaniline can also be used as anodes. Conductive polymers are light in weight and can be solution-processed, having advantages in flexible electronic devices.

[0075] The hole injection layer is of the p-doped type. The p-dopant imparts p-type semiconductor characteristics to the material, can inject or transport holes at the HOMO energy level, improve the hole injection efficiency, and reduce the driving voltage.

[0076] The hole transport material is selected from arylamine derivatives, conductive polymers, and block copolymers containing conjugated and non-conjugated parts. Arylamine derivatives have good hole transport performance; conductive polymers have conductivity and flexibility; the unique structure of block copolymers can adjust various properties to adapt to different processes and device structures.

[0077] The light-emitting auxiliary layer (second hole transport layer) between the hole transport layer and the light-emitting layer can assist in hole transport, block electrons from the cathode, reduce the interlayer barrier, lower the driving voltage, improve the hole utilization rate, and improve the light-emitting efficiency and lifetime.

[0078] The light-emitting layer includes a host material and a dopant material.

[0079] The mass ratio of the host material to the dopant material is 90 - 99.5:0.5 - 10.

[0080] The host material is an aromatic polycyclic derivative or a heterocyclic compound. Specifically, the aromatic polycyclic derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentacene derivatives, phenanthrene compounds or fluoranthene compounds, and the heterocyclic compounds include carbazole derivatives, dibenzofuran derivatives or pyrimidine derivatives.

[0081] The doping materials include fluorescence doping and phosphorescence doping, specifically including aromatic amine derivatives, styrylamine compounds, boron complexes, fluoranthene compounds or metal complexes.

[0082] The electron transport layer promotes electron transport. It includes an electron buffer layer, a hole blocking layer and an electron transport layer, and high electron mobility materials need to be selected, such as aluminum 8-hydroxyquinolate and its derivatives. The electron injection layer promotes electron injection and prevents exciton migration. The materials include derivatives of oxazole, various metals and their alloys, metal complexes, nitrogen-containing five-membered ring derivatives, etc. The cathode selects materials with a small work function, and the layer thickness is 0.5 - 5 nm, such as multi-layer structures of magnesium-aluminum alloy, LiF / A1, etc., which are beneficial to electron injection.

[0083] Except for the fact that the light-emitting auxiliary layer disclosed in the present invention contains Formula I, there are no special restrictions on the materials of other layers in the OLED device. Existing hole injection materials, hole transport materials, hole transport auxiliary materials, doping materials, hole blocking layer materials, electron transport layer materials and electron injection materials can be used.

[0084] The following specifically describes the organic electroluminescent compounds and organic electroluminescent devices provided by the present invention in combination with specific application examples.

[0085] [Application Example 1] Preparation of an organic electroluminescent device:

[0086] a. ITO anode: Wash the ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150 nm twice in distilled water, ultrasonically wash for 30 min, then wash repeatedly twice with distilled water, ultrasonically wash for 10 min. After the washing is completed, bake in a vacuum oven at 220 °C for 2 hours, and then cool down to be used. Using this substrate as the anode, use an evaporation machine to perform the evaporation device process, and sequentially evaporate other functional layers on it.

[0087] b. HIL (hole injection layer): At the evaporation rate, vacuum evaporate the hole injection layer materials HT and P-dopant, and the chemical formulas of HT and P-dopant are shown below; the evaporation rate ratio of HT and P-dopant is 95:5, and the thickness is 10 nm;

[0088] c. HTL (hole transport layer): At The evaporation rate, vacuum evaporate 125 nm of HT on the hole injection layer as the hole transport layer;

[0089] d, Prime (luminescence assisting layer): At The evaporation rate, vacuum evaporate 5 nm of the compound 13 of the present invention on the hole transport layer as the luminescence assisting layer;

[0090] e, EML (luminescent layer): At The evaporation rate, vacuum evaporate a main material (Host) and a dopant material (Dopant) with a thickness of 30 nm on the luminescence assisting layer as the luminescent layer, and the chemical formulas of Host and Dopant are as follows; the evaporation rate ratio of Host and Dopant is 98:2.

[0091] f, HB (hole blocking layer): At The evaporation rate, vacuum evaporate HB with a thickness of 5.0 nm on the luminescent layer as the hole blocking layer.

[0092] g, ETL (electron transport layer): At The evaporation rate, vacuum evaporate ET and Liq with a thickness of 30 nm on the hole blocking layer as the electron transport layer; the evaporation rate ratio of ET and Liq is 50:50.

[0093] h, EIL (electron injection layer): At The evaporation rate, vacuum evaporate a Yb film layer of 1.0 nm on the electron transport layer to form an electron injection layer.

[0094] i, cathode: At The evaporation rate ratio, vacuum evaporate magnesium and silver of 13 nm on the electron injection layer, and the evaporation rate ratio is 1:9 to obtain the cathode.

[0095] j, light extraction layer: At The evaporation rate, vacuum evaporate CPL with a thickness of 60 nm on the cathode as the light extraction layer.

[0096] k, encapsulate the evaporated substrate: First, use a gluing device to coat the cleaned cover plate with UV glue, then move the coated cover plate to the lamination section, place the evaporated substrate on the upper end of the cover plate, and finally laminate the substrate and the cover plate under the action of a laminating device, and at the same time complete the light curing of the UV glue.

[0097]

[0098] Application Example 2 - 89

[0099] The organic electroluminescent device of Application Example 2 - 89 was prepared according to the above - mentioned method for preparing an organic electroluminescent device, with the difference that: Compound 13 in Application Example 1 was replaced with the corresponding compound (as shown in Table 1) to form a light - emitting auxiliary layer.

[0100] Comparative Example 1 - Comparative Example 22

[0101] The organic electroluminescent devices of Comparative Example 1 - Comparative Example 22 were prepared according to the above - mentioned method for preparing an organic electroluminescent device, with the difference that: Compound 13 in Application Example 1 was respectively replaced with Comparative Compound 1 - Comparative Compound 22, and the structural formulas of Comparative Compound 1 - Comparative Compound 22 are as follows:

[0102]

[0103] The driving voltage, luminous efficiency, BI value and lifetime of the organic electroluminescent devices obtained in the above - mentioned Application Examples 1 - 89 and Comparative Examples 1 - 22 were characterized at a brightness of 1000 (nits), and the test results are shown in Table 1 below:

[0104] Table 1 Test Results of Luminescence Characteristics (Brightness Value is 1000 nits)

[0105]

[0106]

[0107]

[0108] As known to those skilled in the art, in a blue - light top - emission device, the luminous efficiency is greatly affected by chromaticity. Therefore, considering the influencing factors of chromaticity on efficiency, the ratio of luminous efficiency to CIEy is defined as the BI value, that is, BI=(cd / A) / CIEy.

[0109] In the prior art, there are compounds substituted with deuterium and compounds not deuterated. From the test data, generally speaking, the compounds of the present invention have an unexpectedly improved lifetime, with an increase of about 160 - 210% compared with the prior art, the efficiency is improved, and the driving voltage is improved.

[0110] Specifically, Comparative Compound 1 and Compound 5 of the present invention, Comparative Compound 2 and Compound 269 of the present invention, Comparative Compound 3 and Compound 270 of the present invention, Comparative Compound 4 and Compound 271 of the present invention are parallel - comparison compounds. The difference is that the position of the dibenzofuran ring in the comparative compound is at the 3,4 - position, while that of the present invention is at the 1,2 - position;

[0111] Comparative compound 6 and the compound 272 of the present invention, and comparative compound 7 and the compound 273 of the present invention are parallel comparative compounds. The difference is that the dibenzofuran and arylamine in the present invention are connected in an ortho manner on the benzene ring, while the corresponding part of the comparative compound is in the meta position;

[0112] Comparative compound 8 and the compound 274 of the present invention; comparative compound 10 and the compound 275 of the present invention are parallel comparative compounds. The difference is only that the dibenzofuran of the comparative compound has no fused ring;

[0113] Comparative compound 12 and the compound 13 of the present invention, comparative compound 15 and the compound 5 of the present invention, comparative compound 18 and the compound 54 of the present invention are parallel comparative compounds. The difference is that the comparative compound has no deuteration;

[0114] In terms of device performance, compared with the parallel comparative compounds, the deuterated compounds of the present invention have an improvement in lifetime of 200%-210% for the compounds of the present invention, exceeding the improvement level of the conventional technical effects in the art.

[0115] Furthermore, the performance improvement of the present invention depends on the comprehensive factors in the following four aspects:

[0116] (1) The 1,2 positions of the dibenzofuran form a fused ring with the phenyl group, which can shorten the conjugated plane, increase the triplet energy level (T1) of the blue light emitting auxiliary layer, and improve the exciton blocking ability;

[0117] (2) The naphthobenzofuran and are connected in an ortho manner on the benzene ring, which makes the molecular configuration extremely distorted, shortens the conjugated length, increases the energy gap, enables the blue light emitting auxiliary material to have a shallower LUMO energy level while ensuring a suitable HOMO energy level, improves the electron blocking ability, increases the number of exciton recombinations, reduces exciton polaron annihilation, improves the efficiency and lifetime, and further increases the triplet energy level at the same time, playing a role in exciton blocking.

[0118] (3) Connecting benzene, biphenyl and other specific groups on can effectively reduce the HOMO energy level to a suitable position, enabling holes to be smoothly injected into the light emitting layer. The HOMO energy level of the side chain being fluorene is shallow, and the HOMO energy level of the side chain being dibenzofuran is deep. Only when the side chain is aryl, the energy level is between -5.60 eV and -5.65 eV, enabling holes to be smoothly injected and migrated to the light emitting layer.

[0119] Table 2 HOMO, LUMO, and T1 values of comparative compounds 1-22 and the compounds of the present invention

[0120]

[0121]

[0122]

[0123] Overall, the blue light-emitting auxiliary layer requires materials with a shallow LUMO energy level, a deep HOMO energy level, and a high triplet energy level. The energy level matching with other functional layers needs to be finely tuned. The HOMO energy level of the compound of the present invention is between -5.6 and -5.65 eV, and the LUMO energy level is between -2.25 and -2.35 eV; the HOMO energy level of the comparative compound is between -5.45 and -5.54 eV, and the LUMO energy level is between -2.45 and -2.55 eV. The triplet energy level of the compound of the present invention is between 2.40 and 2.50 eV, and that of the comparative compound is between 2.25 and 2.35 eV. Thus, although the prior art is similar to the compound of the present invention, the compound of the present invention has carefully designed and selected the fused ring position, the phenyl ortho-linkage mode, and specific aryl groups for the side chain, and a more excellent technical solution capable of improving the performance has been found therefrom.

[0124] (4) Deuterium must be present in the structure. The blue light-emitting auxiliary material is greatly impacted by excitons and is prone to bond breakage. After deuteration, the bond dissociation energy is enhanced and the lifetime is increased.

[0125] Table 3 Changes in dissociation energy before and after deuteration

[0126]

[0127]

[0128] The theoretical calculation of the dissociation energy of D or H at each position on the middle benzene ring of compound 13 and comparative compound 12 shows that at the position containing D, the dissociation energy is higher, the compound is more stable, and the device lifetime is improved.

[0129] 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 apparent 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 rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic electroluminescent material, characterized in that, The structure of the organic electroluminescent material is shown in Formula I: Wherein, R1-R 23 contains at least one deuterium; R1-R 13 Each independently selected from hydrogen, deuterium; R 14 -R 23 Each independently selected from hydrogen, deuterium, group A; adjacent Rs 14 -R 23 are connected to form a benzene ring which is substituted or unsubstituted with deuterium or group A; Group A is selected from the following groups which may or may not be substituted by deuterium: phenyl, naphthyl, biphenyl, naphthyl substituted by benzene.

2. The organic electroluminescent material according to claim 1, characterized in that, R 14 -R 18 any one of which is selected from group A, and the rest are selected from hydrogen or deuterium; R 19 -R 23 Any one of them is selected from group A, and the rest are selected from hydrogen or deuterium.

3. The organic electroluminescent material according to claim 1, wherein Formula I has the following structure:

4. The organic electroluminescent material according to claim 1, wherein The structure of the organic electroluminescent material includes but is not limited to any one of the following compounds:

5. A method for preparing an organic electroluminescent material as described in claim 1, characterized in that, The method is operated as follows: Step 1: Under N2 protection, 1.0 eq of reactant a-I, 1-1.2 eq of reactant b-I, 0.02-0.08 eq of dichloropalladium(II) bis(diphenylphosphino)ferrocene, and 2.0-2.5 eq of potassium carbonate are respectively added to a mixed solvent composed of toluene, ethanol, and water in a volume ratio of 2-4:1:1, heated to 80-90 °C, reacted for 2-6 h, cooled to room temperature, purified by column chromatography, and the obtained solid is dried to obtain intermediate c-I; Step 2: Under N2 protection, 1.0 eq of intermediate c-I, 1.2 eq of reactant d-I, 2.0-3.0 eq of sodium tert-butoxide, 0.02-0.05 eq of 2-cyclohexylphosphino-2,4,6-triisopropylbiphenyl, and 0.02-0.05 eq of tris(dibenzylideneacetone) dipalladium are added to toluene, heated to 90-100 °C, reacted for 2-8 h, cooled to room temperature, purified by column chromatography, and the obtained solid is dried to obtain Formula-I; The specific synthesis route is as follows:

6. An organic electroluminescent device, characterized in that, The organic electroluminescent device comprises the organic electroluminescent material according to any one of claims 1-4.

7. The application according to claim 6, wherein The organic electroluminescent device includes an organic layer; the organic layer contains the organic electroluminescent material.

8. The application according to claim 7, characterized in that The organic electroluminescent material is used as the light-emitting auxiliary layer material of the organic electroluminescent device.

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