Organic electroluminescent material and preparation method and application thereof

Abstract

The present invention belongs to the field of organic electroluminescence, and discloses an organic electroluminescent material and a preparation method and application thereof. The structure of the organic electroluminescent material is shown in Chemical Formula I: The organic electroluminescent material compound provided by the present invention is a parent core body composed of a dibenzofuran group substituted with an aromatic group and a triarylamine group bridged by a naphthylene group. The rigid dibenzofuran structure can effectively enhance the structural stability, and the presence of the triarylamine group can improve the hole transport efficiency of the material. Further, bridging the naphthylene group between the two main structures can form a more efficient conjugated system, improve the electron mobility of the entire material, and enable the device to have high luminous efficiency and long service life while maintaining a low driving voltage.

Description

Technical Field

[0001] The invention belongs to the field of organic electroluminescence, and relates to an organic electroluminescent material, a preparation method and an organic electroluminescent device containing the same. Background Art

[0002] Organic electroluminescence (OLED) refers to the phenomenon of converting electrical energy into light energy using organic substances. Organic electroluminescent devices using the organic electroluminescence phenomenon generally include an anode, a cathode, and an organic layer formed between the two electrodes or outside the two electrodes.

[0003] In order to solve the lifespan and efficiency problems, a light-emitting auxiliary layer is usually added between the hole transport layer and the light-emitting layer. The light-emitting auxiliary layer mainly assists the hole transport layer, so it is sometimes also called the second hole transport layer. The light-emitting auxiliary layer can enable the holes transferred from the anode to move smoothly to the light-emitting layer, and can block the electrons transferred from the cathode to confine the electrons in the light-emitting layer, reduce the potential barrier between the hole transport layer and the light-emitting layer, reduce the driving voltage of the organic electroluminescent device, and further increase the utilization rate of holes, thereby improving the luminous efficiency and life of the device.

[0004] Organic hole transport materials mainly include hydrazones, carbazoles, oxadiazoles, triarylamines, styrenes and butadiene compounds. Among them, triarylamine hole transport materials can form ammonium ion radicals under the action of electric field, have high hole mobility and good photoelectric properties. Triarylamine compounds are centered on nitrogen atoms and connected to three substituents. They have a propeller-like structure, large steric hindrance and hyperconjugation effect, which makes the nitrogen atom radical have high stability. This unique free radical property makes this type of compound have high hole mobility.

[0005] However, there are few materials that can form a light-emitting auxiliary layer and have excellent device performance. In particular, the device life and luminous efficiency are not significantly improved. Therefore, developing a light-emitting auxiliary material with high luminous efficiency, long service life and low driving voltage is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention discloses an organic electroluminescent material and a preparation method and application thereof.

[0007] It should be noted that the organic electroluminescent material structure disclosed in the present invention is based on a dibenzofuran group with aromatic substitution and a triarylamine group bridged by a naphthyl group as the parent core body. The rigid dibenzofuran structure can effectively enhance the structural stability. The presence of the triarylamine group can improve the hole transport efficiency of the material. Further bridging the naphthyl group between the two main structures can form a more efficient conjugated system, thereby improving the electron mobility of the entire material, so that the device has high luminous efficiency and long service life while maintaining a low driving voltage.

[0008] In order to achieve the above-mentioned object, the first object of the present invention is to provide an organic electroluminescent material, which adopts the following technical solution:

[0009] An organic electroluminescent material, the general structural formula of the organic electroluminescent material is shown in Chemical Formula I:

[0010] ;

[0011] in,

[0012] and They are connected to the same benzene ring of naphthalene, and the two are connected in ortho position;

[0013] R1 is selected from hydrogen, substituted or unsubstituted C6-C12 aryl;

[0014] R2 is selected from hydrogen, substituted or unsubstituted C6-C18 aryl;

[0015] Moreover, R1 and R2 cannot be H at the same time;

[0016] Ar1 and Ar2 are independently selected from substituted or unsubstituted C6-C30 aryl groups, substituted or unsubstituted C5-C30 heteroaryl groups, wherein the heteroatom contains at least one of O, S, N, Si and Se.

[0017] Optionally, the chemical formula I has the following structure of chemical formulas IA to IC:

[0018] .

[0019] Furthermore, R1 is selected from hydrogen, phenyl, biphenyl, and naphthyl, and R2 is selected from hydrogen, phenyl, biphenyl, and naphthyl.

[0020] Further, Ar1 and Ar2 are independently selected from the following structures:

[0021] ;

[0022] in,

[0023] R3-R 14are independently selected from hydrogen, deuterium, unsubstituted or deuterium-substituted C1-C6 alkyl;

[0024] R 15 , R 16 Each is independently selected from unsubstituted or deuterium-substituted C1-C6 alkyl;

[0025] n3、n 11 are independently selected from integers from 1 to 5;

[0026] n4 and n8 are independently selected from integers from 1 to 9;

[0027] n5, n6, n 13 are independently selected from integers from 1 to 13;

[0028] n7 and n9 are independently selected from integers from 1 to 7;

[0029] n 10 independently selected from integers from 1 to 8;

[0030] n 12 、n 14 are independently selected from integers from 1 to 11.

[0031] It should be noted that the "substituted" in the substituted or unsubstituted aryl and heteroaryl groups is selected from deuterium, halogen, cyano, TMS, trifluoromethyl, methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, cyclopentane, cyclohexane, phenyl , biphenyl, naphthyl, fluorenyl, dimethylfluorenyl, phenanthryl, anthracenyl, indenyl, triphenylene, pyrenyl, chrysene, furanyl, thienyl, pyrrolyl, pyridyl, benzofuranyl, benzothienyl, isobenzofuranyl, dibenzofuranyl, dibenzothienyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxazolyl, isoindolyl, indolyl, benzindolyl, benzothiadiazolyl, carbazolyl, benzocarbazolyl, or substituted with two or more of the substituents shown above connected to each other.

[0032] In the above technical solution, the organic electroluminescent material is any one of the following structures, but is not limited thereto: .

[0033] The second object of the present invention is to provide a method for preparing the organic electroluminescent material as described above.

[0034] It should be noted that the organic electroluminescent material in the present invention can be prepared by methods known to those skilled in the art. Alternatively, the following reaction process is preferred for preparation, and the specific operation is as follows:

[0035] (1) Add raw material A (1.0 eq), raw material B (1.0-1.3 eq), potassium carbonate (2.0-4.0 eq) and a mixed solution of toluene, ethanol and water (V:V:V=3:1:1) into a reaction flask, then add tetrakis(triphenylphosphine)palladium (0.01-0.03 eq) under nitrogen flow, raise the temperature to 75-95°C for reaction for 1-14 hours; detect the reaction by thin layer chromatography, confirm that the reaction is complete, cool down, add water and dichloromethane for extraction, separate the liquids, combine the organic phases and concentrate, and purify by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=0:1, 1:4-1:10) to obtain intermediate 1;

[0036] (2) Add intermediate 1 (1.0 eq), raw material C (1.0-1.3 eq), sodium tert-butoxide (2.0-4.0 eq) and toluene to a reaction flask, then add tri(dibenzylideneacetone)dipalladium (0.01-0.05 eq) and tri-tert-butylphosphine (0.01-0.10 eq) under nitrogen, raise the temperature to 110-120° C. and react for 4-24 hours; detect the reaction by thin layer chromatography, confirm that the reaction is complete, cool down, add water and dichloromethane for extraction, separate the liquids, combine the organic phases and concentrate, and purify by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:4-1:12) to obtain chemical formula I;

[0037] The specific synthetic route is as follows:

[0038] ;

[0039] Wherein, Ar1, Ar2, R1, R2 are as defined in the above chemical formula I, and X independently represents or , where * is the attachment site.

[0040] In particular, for complex raw materials that have not been disclosed before, the classic Suzuki coupling reaction and Buchwald-Hartwig coupling reaction are used for synthesis and applied to the present invention.

[0041] The third object of the present invention is to provide an application of an organic electroluminescent material. The organic electroluminescent material as described above is applied to an organic electroluminescent device.

[0042] Specifically, the organic electroluminescent device includes a first electrode, a second electrode, and at least one organic layer disposed between the first electrode and the second electrode.

[0043] It should be noted that the organic material layer of the organic electroluminescent device in the present invention can be formed as a single-layer structure or a multilayer structure having two or more organic material layers. For example, the organic electroluminescent device may have a structure including a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting auxiliary layer, a light-emitting layer, an electron transport layer, an electron injection layer, a hole blocking layer, etc. as organic material layers. However, the structure of the organic light-emitting device is not limited thereto, and may include a smaller number of organic material layers or a larger number of organic material layers.

[0044] Specifically, except that the light-emitting auxiliary layer of the present invention contains chemical formula I, there is no special limitation on the materials of other layers in the OLED device.

[0045] Further, the organic electroluminescent device can be used in an organic electroluminescent device, which includes but is not limited to a flat panel display, a computer monitor, a medical monitor, a television, a billboard, a lamp for internal or external lighting and / or signaling, a head-up display, a fully transparent or partially transparent display, a flexible display, a laser printer, a telephone, a mobile phone, a tablet, a photo album, a personal digital assistant (PDA), a wearable device, a laptop computer, a digital camera, a video camera, a viewfinder, a microdisplay, a three-dimensional display, a virtual reality or augmented reality display, a vehicle, a video wall including multiple displays tiled together, a theater or venue screen, a light therapy device and a sign.

[0046] Compared with the prior art, the present invention provides an organic electroluminescent material and a preparation method and application thereof, which have the following excellent effects:

[0047] The material compound disclosed in the present invention is a parent core main structure of a dibenzofuran group substituted with an aromatic group and a triarylamine group bridged by a naphthyl group. As a luminescent auxiliary layer material, the device has high thermal stability, high luminous efficiency and long service life, while maintaining a low driving voltage.

[0048] Specifically, 1) the dibenzofuran group has strong rigidity, which can effectively improve the electrochemical stability and thermal stability of the overall structure, making the material less likely to undergo structural changes at high temperatures, thereby effectively improving the service life of the device. Further connecting an aromatic substituent to the dibenzofuran group can effectively extend the conjugated system of the compound and avoid the localization of carrier migration, thereby maintaining a low driving voltage for the device and improving the luminescence efficiency;

[0049] 2) Due to the presence of nitrogen atoms containing lone pairs of electrons in triarylamine, the electrons on the nitrogen atoms are transferred by transition under the action of an external electric field, so that holes are generated in the molecule, thereby realizing the reverse transfer of holes. In addition, the triarylamine group itself has a high HOMO energy level, which makes it have excellent hole transport performance, which is conducive to the efficient transfer of holes from the anode to the light-emitting layer and reduces the energy loss during the hole transfer process. Further connecting a group that matches its energy level to the triarylamine structure is to add a geometric structure to the non-planar molecular structure to form a compound with a larger spatial configuration, which is more conducive to the transfer of holes and obtains better hole transfer efficiency, thereby improving the luminescence efficiency of the device;

[0050] 3) A bridging naphthyl group is introduced between the dibenzofuran group and the triarylamine group. The dibenzofuran group and the triarylamine group are connected at the ortho position on the same benzene ring of the naphthyl group. This connection method can effectively increase the packing density of the molecule, which is beneficial to the transfer of charges. It can form a longer and more effective conjugated system with the dibenzofuran group and the triarylamine group, thereby improving the electron mobility of the entire material, and thus helping to improve the luminous efficiency of the device. The rigidity of the naphthyl group helps to arrange the molecules in an orderly manner, adjust the energy level of the entire molecule, balance the transfer of electrons and holes, ensure the charge balance in the device, and also improve the thermal stability of the molecule, making the material less likely to undergo structural changes and cracking during high-temperature evaporation, thereby increasing the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0052] Figure 1 is the H NMR spectrum of compound 1. DETAILED DESCRIPTION

[0053] The technical solution 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The invention specifically discloses an organic electroluminescent material and a preparation method and application thereof.

[0055] It should be noted that the numerical values ​​given in the following examples are as accurate as possible, but due to inevitable measurement errors and experimental operation problems of those skilled in the art, each number should be understood as an approximate number rather than an absolutely accurate value.

[0056] The specific embodiments described below are only part of the embodiments of the present application, rather than all the embodiments.

[0057] The features and performance of the present invention will be further described in detail below with reference to the embodiments.

[0058] Example 1

[0059] ;

[0060] Raw material A-1 (1.0 eq, CAS number: 1822310-23-5), raw material B-1 (1.1 eq, CAS number: 71436-66-3), potassium carbonate (3.0 eq) and a mixed solution of toluene, ethanol and water (V:V:V=3:1:1) were added to the reaction flask, and then tetrakis(triphenylphosphine)palladium (0.01 eq) was added under nitrogen flow, and the temperature was raised to 95°C for reaction for 5 hours; the reaction was detected by thin layer chromatography, and after confirmation of the completion of the reaction, the temperature was lowered, water and dichloromethane were added for extraction and separation, the organic phases were combined and concentrated, and a mixed solution of dichloromethane and petroleum ether (V:V=1:6) was used for purification by column chromatography to obtain intermediate 1 (yield: 74.7%).

[0061] Intermediate 1 (1.0 eq), raw material C-1 (1.1 eq, CAS number: 897671-69-1), sodium tert-butoxide (2.0 eq) and toluene were added to the reaction flask, and then tri(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added under nitrogen. The temperature was raised to 120°C and the reaction was carried out for 12 hours. The reaction was detected by thin layer chromatography. After the reaction was confirmed to be complete, water and dichloromethane were added for extraction and separation. The organic phases were combined and concentrated, and a mixed solution of dichloromethane and petroleum ether (V:V=1:5) was used for purification by column chromatography to obtain compound 1 (yield: 83.3%).

[0062] The obtained compound 1 was tested and analyzed, and the results were as follows:

[0063] HPLC purity: >99.8%.

[0064] Mass spectrometry test: The model is Waters XEVO TQD mass spectrometer, using ESI source.

[0065] Test value MS (ESI, m / Z): [M+H] + =729.59.

[0066] Elemental Analysis:

[0067] Calculated values: C, 90.50; H, 5.39; N, 1.92; O, 2.19;

[0068] The test values ​​are: C, 90.17; H, 5.53; N, 2.08; O, 2.34.

[0069] H NMR spectrum: Figure 1 (Compound 1) shown.

[0070] Example 2

[0071] ;

[0072] Raw material A-146 (1.0 eq, CAS number: 2025367-42-2), raw material B-146 (1.1 eq, CAS number: 692728-68-0), potassium carbonate (3.0 eq) and a mixed solution of toluene, ethanol and water (V:V:V=3:1:1) were added to the reaction flask, and then tetrakis(triphenylphosphine)palladium (0.01 eq) was added under nitrogen flow, and the temperature was raised to 95°C for reaction for 6 hours; the reaction was detected by thin layer chromatography, and after confirmation of the completion of the reaction, the temperature was lowered, water and dichloromethane were added for extraction and separation, the organic phases were combined and concentrated, and a mixed solution of dichloromethane and petroleum ether (V:V=1:6) was used for purification by column chromatography to obtain intermediate 1 (yield: 74.2%).

[0073] Intermediate 1 (1.0 eq), raw material C-146 (1.1 eq, CAS number: 32228-99-2), sodium tert-butoxide (2.0 eq) and toluene were added to a reaction flask, and then tri(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added under nitrogen. The temperature was raised to 120°C and the reaction was carried out for 14 h. The reaction was detected by thin layer chromatography. After the reaction was confirmed to be complete, water and dichloromethane were added for extraction and separation. The organic phases were combined and concentrated, and purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:4) to obtain compound 146 (yield: 81.9%).

[0074] The obtained compound 146 was tested and analyzed, and the results were as follows:

[0075] HPLC purity: >99.6%.

[0076] Mass spectrometry test: The model is Waters XEVO TQD mass spectrometer, using ESI source.

[0077] Test value MS (ESI, m / Z): [M+H] + =613.53.

[0078] Elemental Analysis:

[0079] Calculated values: C, 90.02; H, 5.09; N, 2.28; O, 2.61;

[0080] Test values: C, 89.68; H, 5.22; N, 2.42; O, 2.75.

[0081] Example 3

[0082] ;

[0083] Raw material A-284 (1.0 eq, CAS number: 1010068-85-5), raw material B-284 (1.1 eq, CAS number: 71436-67-4), potassium carbonate (3.0 eq) and a mixed solution of toluene, ethanol and water (V:V:V=3:1:1) were added to the reaction flask, and then tetrakis(triphenylphosphine)palladium (0.01 eq) was added under nitrogen flow, and the temperature was raised to 95°C for reaction for 6 hours; the reaction was detected by thin layer chromatography, and after confirmation of the completion of the reaction, the temperature was lowered, water and dichloromethane were added for extraction and separation, the organic phases were combined and concentrated, and the intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V=1:6) to obtain intermediate 1 (yield: 73.9%).

[0084] Intermediate 1 (1.0 eq), raw material C-284 (1.1 eq, CAS number: 1456544-72-1), sodium tert-butoxide (2.0 eq) and toluene were added to a reaction flask, and then tri(dibenzylideneacetone)dipalladium (0.02 eq) and tri-tert-butylphosphine (0.05 eq) were added under nitrogen. The temperature was raised to 120°C and the reaction was carried out for 13 h. The reaction was detected by thin layer chromatography. After the reaction was confirmed to be complete, water and dichloromethane were added for extraction and separation. The organic phases were combined and concentrated, and a mixed solution of dichloromethane and petroleum ether (V:V=1:5) was used for purification by column chromatography to obtain compound 284 (yield: 82.6%).

[0085] The obtained compound 284 was tested and analyzed, and the results were as follows:

[0086] HPLC purity: >99.7%.

[0087] Mass spectrometry test: The model is Waters XEVO TQD mass spectrometer, using ESI source.

[0088] Test value MS (ESI, m / Z): [M+H] + =739.58.

[0089] Elemental Analysis:

[0090] Calculated values: C, 90.90; H, 5.04; N, 1.89; O, 2.16;

[0091] Analytical values: C, 90.55; H, 5.19; N, 2.04; O, 2.32.

[0092] Example 4-55

[0093] The following compounds were synthesized by referring to the preparation methods of Examples 1 to 3 and tested using a Waters XEVOTQD mass spectrometer with low precision. The ESI source was used for testing, and the mass spectrometry test values ​​are shown in Table 1 below.

[0094] Table 1 Mass spectrometry test values ​​of Examples 4-55

[0095]

[0096] In addition, it should be noted that other compounds of the present invention can be obtained by referring to the preparation methods of the above-mentioned embodiments, so they are not listed one by one here.

[0097] The organic electroluminescent device provided by the present invention is described below in conjunction with specific embodiments.

[0098] Device Example 1: Preparation of blue organic electroluminescent device

[0099] The structure of the prepared OLED device is: ITO anode / HIL / HTL / Prime / EML / HBL / ETL / EIL / cathode / CPL.

[0100] a. ITO anode: The ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 1500Å was cleaned in distilled water for 3 times, ultrasonically washed for 40 minutes, and then repeatedly cleaned with distilled water for 3 times, ultrasonically washed for 20 minutes. After washing, it was ultrasonically washed with methanol, acetone, and isopropanol in sequence (5 minutes each time), dried, and then transferred to a plasma cleaning machine for washing for 5 minutes. It was then sent to a vapor deposition machine, and the substrate was used as the anode, and other functional layers were deposited on it in sequence.

[0101] b. HIL (hole injection layer): Hole injection layer materials HT and P-dopant with a thickness of 10 nm were vacuum evaporated at a deposition rate of 1 Å / s. The chemical formula thereof is shown below, and the deposition rate ratio of HT and P-dopant was 97:3.

[0102] c. HTL (hole transport layer): 125 nm of HT was vacuum-deposited on the hole injection layer at a deposition rate of 1.5 Å / s as the hole transport layer.

[0103] d. Prime (luminescence auxiliary layer): 5 nm of compound 1 was vacuum-deposited on the hole transport layer at a deposition rate of 0.5 Å / s as a luminescence auxiliary layer.

[0104] e. EML (light-emitting layer): At a deposition rate of 1Å / s, a host material (Host) and a dopant material (Dopant) with a thickness of 30nm are vacuum-deposited on the light-emitting auxiliary layer as the light-emitting layer. The chemical formulas of Host and Dopant are shown below, and the deposition rate ratio of Host and Dopant is 98:2.

[0105] f. HBL (hole blocking layer): HB with a thickness of 5 nm was vacuum-deposited on the light-emitting layer at a deposition rate of 0.5Å / s as a hole blocking layer.

[0106] g. ETL (electron transport layer): ET and Liq with a thickness of 30 nm were vacuum-deposited on the hole blocking layer at a deposition rate of 1 Å / s as an electron transport layer. The chemical formula of ET is shown below, and the deposition rate ratio of ET and Liq is 50:50.

[0107] h. EIL (electron injection layer): A Yb film with a thickness of 1 nm is vacuum-deposited on the electron transport layer at a deposition rate of 0.5 Å / s to form an electron injection layer.

[0108] i. Cathode: Magnesium and silver with a thickness of 13 nm were vacuum evaporated on the electron injection layer at a deposition rate of 1Å / s. The deposition rate ratio of magnesium to silver was 1:9 to obtain a cathode.

[0109] j. CPL (light extraction layer): CPL with a thickness of 65 nm is vacuum-deposited on the cathode at a deposition rate of 1Å / s as a light extraction layer.

[0110] k. Package the vapor-deposited substrate: first, use the glue coating equipment to coat the cleaned cover with UV glue, then move the coated cover to the pressing section, place the vapor-deposited substrate on the upper end of the cover, and finally bond the substrate and cover with the bonding equipment, and complete the light curing of the UV glue at the same time.

[0111] The structures of HT, P-dopant, Host, Dopant, HB, ET, and CPL used in the device embodiment 1 are as follows:

[0112] .

[0113] Device Example 2-55:

[0114] Referring to the method provided in the above device embodiment 1, the corresponding compounds in Table 2 were selected to replace compound 1, and the luminescent auxiliary layer was evaporated to prepare the corresponding organic electroluminescent devices, which were respectively recorded as device embodiments 2 to 55.

[0115] Device Comparison Examples 1-5:

[0116] The only difference between the preparation method of the organic electroluminescent device in device comparative examples 1-5 and device example 1 is that the organic electroluminescent device uses the existing compound ae to replace the organic electroluminescent material (compound 1) in the above device example 1 for evaporation. The chemical structure of compound ae is as follows:

[0117] .

[0118] At a brightness of 1000 (nits), the driving voltage, BI value and lifespan of the organic electroluminescent devices obtained from the device embodiments 1-55 and the device comparative examples 1-5 were characterized. The test results are shown in Table 2 below:

[0119] Table 2 Device test results

[0120]

[0121] Those skilled in the art will know that in a blue top-emitting device, the luminous efficiency is greatly affected by chromaticity. Therefore, the influence of chromaticity on efficiency is taken into account, and the ratio of luminous efficiency to CIEy is defined as the BI value, that is, BI = (cd / A) / CIEy.

[0122] It can be seen from Table 2 that, compared with the organic electroluminescent device prepared using the organic electroluminescent material provided by the present invention and the organic electroluminescent device prepared using the comparative example compound, the luminous efficiency and service life of the device are effectively improved while maintaining a lower driving voltage.

[0123]

[0124] Compounds a, b and compounds 188, 91 are parallel comparative examples, and the difference between them is that the dibenzofuran in compounds a and b is connected to a non-hydrogen substituent, while the dibenzofuran in compounds 188 and 91 of the present invention is connected to an aromatic group (phenyl) on the outside, which effectively extends the conjugated system of the compound and avoids the localization of carrier migration, thereby maintaining a low driving voltage and improving the luminescence efficiency.

[0125]

[0126] Compound c and compound 237 are parallel comparative examples, the difference between them is that in compound 237 of the present invention, the outside of dibenzofuran is connected to a biphenyl group, while the corresponding position in compound c is connected to a 9,9-dimethylfluorenyl group. The introduction of the 9,9-dimethylfluorenyl group will make the HOMO energy level shallow, which will cause the injection energy barrier between the luminescent auxiliary layer and the luminescent layer to increase, thereby increasing the voltage, accumulating interface holes, and shortening the lifetime. In addition, the molecular weight of the 9,9-dimethylfluorenyl group is larger, which will cause the evaporation temperature to increase, thereby affecting the stability of the material structure.

[0127]

[0128] Compound d and compound 123 are parallel comparative examples, the difference between them is that in the compound 123 of the present invention, there is an unsubstituted naphthylene group as a bridging group between dibenzofuran and triarylamine, while in compound d, there is also a methoxy group on the bridging naphthylene group. The presence of the methoxy group will increase the rotational freedom within the molecule and reduce the orderly arrangement of the molecules, thereby affecting the stability of the molecules, resulting in the material being easily degraded during the device evaporation process, thereby affecting the service life of the device.

[0129]

[0130] Compound e is a compound in the applicant's prior research patent CN117164537A, and is a parallel comparative example with compound 264 in the present invention. The difference between them is that one group on the triarylamine in compound 264 of the present invention is an unsubstituted biphenyl group, while the biphenyl group at the corresponding position in compound e is further substituted by an adamantyl group. The adamantyl group has a large volume and large steric hindrance, which not only affects the uniformity of film formation, but also hinders the free transfer of charges, causing the evaporation temperature to increase, thereby affecting the stability of the material.

[0131] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may 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 the 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 as follows: 。 2. An application of an organic electroluminescent material, characterized in that: The organic electroluminescent material as claimed in claim 1 is used in an organic electroluminescent device.

3. The use according to claim 2, characterized in that: The organic electroluminescent device comprises an organic layer; the organic layer contains the organic electroluminescent material.

4. The use according to claim 3, characterized in that: The organic electroluminescent material is used as a light-emitting auxiliary layer material.

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