Boron-containing compound containing 9, 9 '-dicarbazole and organic electroluminescent device thereof

Abstract

The invention discloses a boron-containing compound containing 9, 9 '-dicarbazole and an organic electroluminescent device thereof, the boron-containing compound containing 9, 9'-dicarbazole not only has the advantages of high luminous efficiency, stable chemical property and low driving voltage, but also introduces a 9, 9 '-dicarbazole structure, so that on one hand, the material has relatively large steric hindrance, molecular accumulation is effectively inhibited, and the luminous efficiency is improved; on the other hand, due to the axial chirality characteristic brought by the 9, 9 '-dicarbazole structure, the compound has circularly polarized luminescence performance. By introducing a multi-resonance structural unit, the luminescent material shows a small half-peak width, and by modifying the periphery of a molecule, the luminescent position and the half-peak width of the material can be finely adjusted within the wavelength range of visible light, so that convenience is provided for design and production of an organic electroluminescent display and a lighting source. The preparation method is simple, raw materials are easy to obtain, the yield is high, chemical modification aiming at the structure is flexible, and the industrial development requirement can be met. Boron compound provided by the invention has a structure as shown in formula 1: # imgabs0 #

Description

Technical Field

[0001] The invention relates to a boron-containing compound containing 9,9'-bicarbazole and an organic electroluminescent device thereof, belonging to the technical field of organic electroluminescent materials. Background Art

[0002] With the increasing demand for display technology, organic light-emitting diodes (OLEDs) have attracted great attention and research due to their many advantages such as light weight, high contrast, wide viewing angle, high energy efficiency and significant design adaptability.

[0003] The core of OLED display technology is the light-emitting layer technology, in which the properties of the light-emitting material directly determine the properties of the OLED device. The changes in light-emitting materials have gone through fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescent materials. At present, thermally activated delayed fluorescent materials with pure organic structure and theoretical internal quantum efficiency of 100% have been widely studied by scientific researchers. However, due to its molecular design requirements, it is necessary to use donor groups and acceptor groups to form a mutually twisted configuration, so as to achieve effective separation of the highest occupied orbital and the lowest unoccupied empty orbital of the molecule, and finally achieve a smaller singlet-triplet energy level difference (△E ST However, such a molecular structure will increase the structural relaxation and Stokes shift of the material in the excited state, resulting in the material presenting a wider (half-peak width>70nm) electroluminescent spectrum, thereby reducing the color purity of the luminescence, which is extremely unfavorable for OLED high-resolution display.

[0004] The problem of wide half-width of the spectrum of TADF materials has been bothering researchers until 2016, when Takuji Hatakeyama's research team at Kwansei Gakuin University in Japan creatively proposed a multi-resonance effect-induced thermally activated delayed fluorescence material, which achieved high color purity and attracted widespread attention from the academic community. Multi-resonance effect design strategy: In the molecule, the highest occupied orbital and the lowest unoccupied empty orbital are separated by opposite resonance effects on the same π-conjugated plane. Therefore, the multi-resonance effect reduces structural relaxation and suppresses vibrational electron coupling, achieving a narrower emission half-width. And OLED devices based on such materials all show advantages such as high color purity (half-width <30nm) and high external quantum efficiency (>20%).

[0005] Although the multiple resonance effect has a smaller half-peak width, the multiple resonance effect-induced thermally activated delayed fluorescence material molecules usually have a relatively large energy splitting between the first singlet state and the first triplet state, which leads to a slow reverse intersystem crossing speed, thereby extending the delayed fluorescence lifetime. Therefore, many molecules suffer from severe triplet-involved quenching processes, which destroy the electroluminescence efficiency and cause a large efficiency roll-off at high brightness. In addition, the multiple resonance effect-induced thermally activated delayed fluorescence material molecules usually have a relatively flat molecular structure, which can lead to intermolecular aggregation quenching, thereby reducing the luminescence efficiency of the device. In addition, the energy transfer process between the main material and the luminescent material in the light-emitting layer has a significant impact on the luminescence efficiency and device life of the organic light-emitting device. In order to improve the display quality of the organic light-emitting device, how to develop a light-emitting material with excellent performance is an important direction of current material development. Summary of the invention

[0006] The purpose of the present invention is to address the defects and deficiencies of the above-mentioned prior art and propose a boron-containing compound containing 9,9'-bicarbazole and an organic electroluminescent device thereof. The boron-containing compound containing 9,9'-bicarbazole of the present invention not only has the advantages of high luminous efficiency, stable chemical properties, low driving voltage, etc., but also due to the introduction of the 9,9'-bicarbazole structure, on the one hand, the material has a large steric hindrance, effectively inhibits molecular stacking, and improves luminous efficiency; on the other hand, due to the axial chirality characteristics brought by the 9,9'-bicarbazole structure, it has circularly polarized luminescent properties. In addition, by introducing a structure with a multiple resonance effect, the luminescent material presents a small half-peak width, and by modifying the periphery of the molecule, the luminescent position and half-peak width of the material can be finely adjusted within the visible light wavelength range, which provides convenience for the design and production of organic electroluminescent displays and lighting sources. At the same time, the preparation method of a boron-containing compound containing 9,9'-bicarbazole of the present invention is simple, the raw materials are easily available, the yield is high, the chemical modification of the structure is flexible, and it can meet the development needs of industrialization. When the compound of the present invention is used as a luminescent material in an OLED device, the device can exhibit excellent performance and stability. It has a good wavelength range, low starting voltage, high luminous efficiency and long device life, and has good commercial application prospects.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] The first technical purpose of the present invention is to provide a boron-containing compound containing 9,9′-bicarbazole, wherein the general structural formula of the boron-containing compound containing 9,9′-bicarbazole is as follows:

[0009]

[0010] Wherein X1 and X2 are each independently selected from one of NR', S, and O;

[0011] wherein Ar1 and Ar2 are the same or different and are independently selected from a substituted or unsubstituted six-membered aromatic ring, a substituted or unsubstituted six-membered heterocyclic ring, a substituted or unsubstituted five-membered heterocyclic ring, or a substituted or unsubstituted aromatic condensed ring unit; the aromatic condensed ring unit contains one or more of a six-membered aromatic ring, a six-membered heterocyclic ring, and a five-membered heterocyclic ring, and the aromatic condensed ring unit is connected to B, N, O, or S via a six-membered aromatic ring, a six-membered heterocyclic ring, or a five-membered heterocyclic ring;

[0012] The R′ is selected from a substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, and a substituted or unsubstituted C5-C60 heteroaromatic group.

[0013] Furthermore, the luminescent material is characterized in that the structure of the 9,9′-bicarbazole is as follows:

[0014] The structure of D1 is:

[0015] Wherein the D2 structure is selected from any one of the following structures:

[0016]

[0017] wherein Ar1 and Ar2 are the same or different and are independently selected from a substituted or unsubstituted six-membered aromatic ring, a substituted or unsubstituted six-membered heterocyclic ring, a substituted or unsubstituted five-membered heterocyclic ring, or a substituted or unsubstituted aromatic condensed ring unit; the aromatic condensed ring unit contains one or more of a six-membered aromatic ring, a six-membered heterocyclic ring, and a five-membered heterocyclic ring, and the aromatic condensed ring unit is connected to B, N, O, or S via a six-membered aromatic ring, a six-membered heterocyclic ring, or a five-membered heterocyclic ring;

[0018] The R1, R2, R3 and R4 described in the present invention are each independently selected from a substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, and a substituted or unsubstituted C5-C60 heteroaromatic group.

[0019] Furthermore, the boron-containing compound containing 9,9′-bicarbazole specifically has the following structure, but is not limited thereto:

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] The specific synthetic route of the preparation method of a boron-containing compound containing 9,9'-bicarbazole of the present invention (most compounds can be synthesized by the following general formula, including but not limited to this general formula), the following examples of compound synthesis, composition, device or method are only to provide a general method for the industry, and are not used to limit the scope of protection of the patent. The data (quantity, temperature, etc.) mentioned in the patent are as accurate as possible, but there may be some errors. A preparation method of a boron-containing compound containing 9,9'-bicarbazole, the first synthetic route is as follows:

[0028]

[0029] In the above formula, X1, X2, Ar1, and Ar2 are as defined in the above general formula.

[0030] The specific preparation method includes:

[0031] (1) Synthesis of intermediate a:

[0032] At room temperature, [Ir(COD)(OMe)]2 and 4,4′-di-tert-butyl-2,2′-bipyridine are added to raw materials a and b, and then a certain amount of organic solvent is added to dissolve them. The mixture is reacted for a period of time in an inert gas protection environment. After the reaction is completed, the reaction mixture is purified to obtain intermediate a.

[0033] (2) Synthesis of target compound:

[0034] Add raw material c into a two-necked flask and dissolve it in acetone. Then add strong oxidant potassium permanganate and reflux in an inert gas protection environment for a period of time. After the reaction is completed, the mother liquor is cooled to room temperature, and then extracted with an organic solvent and water, and then dried with a desiccant. Then, the excess solvent is evaporated by reduced pressure distillation, and then purified by silica gel chromatography, and finally dried to obtain intermediate b.

[0035] Potassium carbonate and an organic solvent are added to intermediate b and intermediate a, a catalyst is added under an inert gas protection environment, and then the mixture is heated to reflux, reacted for a period of time, and then extracted, dried, and purified to finally obtain intermediate c. Potassium carbonate and an organic solvent are then added to intermediate c and raw material d, a catalyst is added under an inert gas protection environment, and then the mixture is heated to reflux, reacted for a period of time, and then extracted, dried, and purified to obtain the target compound.

[0036] A method for preparing a boron-containing compound containing 9,9′-bicarbazole, the second synthetic route is as follows

[0037]

[0038] In the above formula, X1, X2, Ar1, and Ar2 are as defined in the above general formula.

[0039] The specific preparation method includes:

[0040] (1) Synthesis of intermediate a:

[0041] The same as synthetic route 1.

[0042] (2) Synthesis of target compound:

[0043] Add strong base potassium carbonate and organic solvent to raw material c and intermediate a, add catalyst under inert gas protection environment, then heat the mixture to reflux, react for a period of time, extract, dry and purify to finally obtain intermediate d. Add raw material c and intermediate d to a two-necked flask, dissolve in acetone, add strong oxidant potassium permanganate, reflux and react for a period of time under inert gas protection environment, cool the mother liquor to room temperature after the reaction, extract, dry and purify to finally obtain intermediate e. Then add potassium carbonate and organic solvent to intermediate e and raw material d, add catalyst under inert gas protection environment, then heat the mixture to reflux, react for a period of time, extract, dry and purify to finally obtain the target compound.

[0044] Furthermore, the present invention also claims to protect the application of the above-mentioned boron-containing compound containing 9,9′-bicarbazole, and the boron-containing compound containing 9,9′-bicarbazole can be used in the preparation of an organic electroluminescent device.

[0045] Specifically, the organic electroluminescent device includes a cathode, an anode, and one or more organic layers disposed between the cathode and the anode; and the organic layers include one of a hole injection layer, a hole transport layer, a luminescence auxiliary layer, a luminescent layer, an electron transport layer and an electron injection layer; and the luminescent layer contains the boron-containing compound containing 9,9′-bicarbazole.

[0046] Furthermore, the organic electroluminescent device of the present invention can be used in an organic electroluminescent device.

[0047] The organic electroluminescent device includes, but is not limited to, a flat panel display, a computer monitor, a medical monitor, a television, a billboard, a lamp for lighting 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 photo album, a wearable device, a laptop computer, a digital camera, a video camera, 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.

[0048] Beneficial effects:

[0049] 1. The boron-containing compound introduced with the 9,9′-bicarbazole structure of the present invention has the advantages of high luminous efficiency, stable chemical properties, low driving voltage, etc. Due to the introduction of the 9,9′-bicarbazole structure, on the one hand, the material has a large steric hindrance, effectively inhibiting molecular accumulation and improving luminous efficiency; on the other hand, due to the axial chirality brought by the 9,9′-bicarbazole structure, it has circularly polarized luminescence performance;

[0050] 2. In addition, by introducing MR-TADF, the luminescent material exhibits a small half-peak width. By modifying the periphery of the molecule, the luminescent position and half-peak width of the material can be finely adjusted within the visible light wavelength range, which facilitates the design and production of organic electroluminescent displays and lighting sources.

[0051] 3. At the same time, the synthetic material of the boron-containing compound containing 9,9′-bicarbazole of the present invention is simple and cheap, the preparation method is simple, the yield is high, the chemical modification of the structure is flexible, and it can meet the development needs of industrialization;

[0052] 4. When the compound of the present invention is used as a light-emitting material in an OLED device, the device can exhibit excellent performance and stability, have a good wavelength range, a low starting voltage, high luminous efficiency and a long device life, and has good commercial application prospects. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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 embodiment of the present invention discloses a method for preparing a boron-containing compound containing 9,9'-bicarbazole.

[0055] In addition, it should be noted that the following examples of compound synthesis, composition, device or method are only to provide a general method for the industry, and are not intended to limit the scope of protection of the patent. The numerical values ​​given in the following examples are as accurate as possible, but those skilled in the art understand that due to unavoidable measurement errors and experimental operation problems, each number should be understood as an approximate number rather than an absolutely accurate value.

[0056] Example 1

[0057] In this embodiment, the preparation of the above-mentioned compound 1 is involved, and the specific preparation process is as follows, and the synthetic route is as follows:

[0058]

[0059] Synthesis of intermediate 1-1:

[0060] At room temperature, the catalyst [Ir (COD) (OMe)] 2 (43.1 mg, 0.065 mmol, 0.01 eq.) and dtbpy (34.9 mg, 0.13 mmol, 0.02 eq.) were added to raw material 1 (2.73 g, 6.5 mmol, 1.0 eq.) and raw material 2 (1.68 g, 6.5 mmol, 1.0 eq.), and ultra-dry THF (60 mL) was added to the reaction bottle. The mixture was then bubbled with nitrogen for 5 minutes, heated to reflux and stirred for 24 hours. After cooling to room temperature, the reaction mixture was directly concentrated under reduced pressure and purified by column chromatography to obtain intermediate 1-1: 3.02 g, with a yield of: 85%.

[0061] Synthesis of intermediate 1-2:

[0062] Add raw material 3 (1.22 g, 5.0 mmol, 1.0 eq.) and 20 mL of acetone into a two-necked flask, mix and then add KMnO4 (1.98 g, 12.5 mmol, 2.5 eq.), slowly fill the reaction flask with nitrogen, bubble for a few minutes to remove oxygen, heat the reaction system to 60 ° C, reflux for 6 hours, cool to room temperature after the reaction, extract the product with DCM, wash with saturated sodium thiosulfate solution, dry with anhydrous sodium sulfate, and separate and purify by column chromatography to obtain intermediate 1-2: 0.98 g, yield: 40%.

[0063] Synthesis of intermediate 1-3:

[0064] Water (2 mL) and THF (16 mL) were added to Intermediate 1-1 (0.137 g, 0.25 mmol, 0.5 eq.), Intermediate 1-2 (0.244 g, 0.5 mmol, 1.0 eq.) and K2CO3 (0.138 g, 1 mmol, 2.0 eq.). The mixture was bubbled with nitrogen for another 5 minutes, and Pd(PPh3)4 (28.89 mg, 0.025 mmol, 0.05 eq.) was added under high flow nitrogen. The mixture was then heated to reflux and stirred for 12 hours. After cooling to room temperature, the reaction mixture was extracted with dichloromethane and water, the combined organic layers were concentrated in vacuo, and the crude product was then purified by column chromatography to give Intermediate 1-3: 145 mg, 35% yield.

[0065] Synthesis of target compound 1:

[0066] To intermediate 1-3 (0.497 g, 0.6 mmol, 1.0 eq.), raw material 4 (0.112 g, 0.3 mmol, 0.5 eq.) and K2CO3 (0.138 g, 1 mmol, 2.0 eq.) were added water (2 mL) and THF (16 mL). The mixture was bubbled with nitrogen for another 5 minutes, and Pd(PPh3)4 (28.89 mg, 0.025 mmol, 0.05 eq.) was added under high flow nitrogen. The mixture was then heated to reflux and stirred for 12 hours. After cooling to room temperature, the reaction mixture was extracted with dichloromethane and water, the combined organic layers were concentrated in vacuo, and the crude product was then purified by column chromatography to obtain the target compound 1: 191 mg with a yield of 32%.

[0067] Example 2

[0068] In this embodiment, the preparation of the above-mentioned compound 50 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0069]

[0070] Synthesis of intermediate 50-1:

[0071] The synthesis of intermediate 50-1 is consistent with the synthesis method of intermediate 1-1, except that raw material 1 is replaced by raw material 5, and the yield of intermediate 50-1 is 82%.

[0072] Synthesis of intermediate 50-2:

[0073] The specific operation method for the synthesis of intermediate 50-2 can refer to the synthesis operation method of intermediate 1-3 in Example 1, the difference is that intermediate 1-1 in the synthesis of intermediate 1-3 is replaced by intermediate 50-1, and intermediate 1-2 is replaced by raw material 3, and the yield of intermediate 50-2 is 32%.

[0074] Synthesis of intermediate 50-3:

[0075] The specific operation method for the synthesis of intermediate 50-3 can refer to the synthesis operation method of intermediate 1-2 in Example 1, except that raw material 3 in the synthesis of intermediate 1-2 is replaced with intermediate 50-2 and raw material 3, and the yield of intermediate 50-3 is 38%.

[0076] Synthesis of target compound 50:

[0077] The specific operation method for synthesizing the target compound 50 can refer to the synthesis method of the target compound 1 in Example 1, except that the intermediate 1-3 in the synthesis of the target compound 1 is replaced with the intermediate 50-3, and the yield of the target compound 50 is 30%.

[0078] Example 3

[0079] In this embodiment, the preparation of the above-mentioned compound 109 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0080]

[0081] Synthesis of intermediate 109-1:

[0082] The synthesis of intermediate 109-1 is consistent with the synthesis method of intermediate 1-1, except that raw material 1 is replaced by raw material 6, and the yield of intermediate 109-1 is 78%.

[0083] Synthesis of intermediate 109-2:

[0084] The specific operation method for the synthesis of intermediate 109-2 can refer to the synthesis method of intermediate 1-3 in Example 1, the difference is that intermediate 1-1 in the synthesis of intermediate 1-3 is replaced by intermediate 109-1, and intermediate 1-2 is replaced by raw material 3, and the yield of intermediate 109-2 is 34%.

[0085] Synthesis of intermediate 109-3:

[0086] The specific operation method for the synthesis of intermediate 109-3 can refer to the synthesis method of intermediate 1-2 in Example 1, except that raw material 3 in the synthesis of intermediate 1-2 is replaced with intermediate 109-2 and raw material 3, and the yield of intermediate 109-3 is 33%.

[0087] Synthesis of target compound 109:

[0088] The specific operation method for synthesizing the target compound 109 can refer to the synthesis method of the target compound 1 in Example 1, except that the intermediate 1-3 in the synthesis of the target compound 1 is replaced with the intermediate 109-3, and the yield of the target compound 109 is 36%.

[0089] Example 4

[0090] In this embodiment, the preparation of the above-mentioned compound 158 is involved. The specific preparation process is as follows, and the synthetic route is as follows:

[0091]

[0092] Synthesis of intermediate 158-1:

[0093] The synthesis of intermediate 158-1 is consistent with the synthesis method of intermediate 1-1, except that raw material 1 is replaced by raw material 7, and the yield of intermediate 158-1 is 84%.

[0094] Synthesis of intermediate 158-2:

[0095] The synthesis of intermediate 158-2 was consistent with that of intermediate 1-2.

[0096] Synthesis of intermediate 158-3:

[0097] The specific operation method for the synthesis of intermediate 158-3 can refer to the synthesis method of intermediate 1-3 in Example 1, the difference is that intermediate 1-1 in the synthesis of intermediate 1-3 is replaced by intermediate 158-1, and intermediate 1-2 is replaced by raw material 158-2, and the yield of intermediate 158-2 is 33%.

[0098] Synthesis of target compound 158:

[0099] The specific operation method for synthesizing the target compound 158 can refer to the synthesis method of the target compound 1 in Example 1, except that the intermediate 1-3 in the synthesis of the target compound 1 is replaced with the intermediate 158-3, and the yield of the target compound 109 is 30%.

[0100] The synthesis methods of other compounds are the same as those in the above embodiments and are not described in detail here.

[0101] Several examples of using the axially chiral boron-containing compound containing 9,9′-bicarbazole in OLED devices are listed below to further illustrate the beneficial effects of the compound of the present invention. The materials used in the examples are purchased from commercial sources or synthesized by the user.

[0102] The preparation method of the device embodiment of the present invention is only used as a reference. The basic steps are: 50-500nm ITO / Ag / ITO is evaporated on an alkali-free glass substrate as an anode, and a hole injection layer (5nm-20nm), a hole transport layer (50-120nm), a luminescent auxiliary layer (5-120nm), a luminescent layer (20-50nm), an electron transport layer (20-80nm), and an electron injection layer (1-10nm) are evaporated on the anode, and then Mg and Ag (weight ratio 10:1, 10-50nm) are co-evaporated to make a semi-transparent cathode, and then a covering layer compound is evaporated, and finally the light-emitting device is encapsulated with an epoxy resin adhesive in a nitrogen atmosphere.

[0103] Device Example 1: Manufacturing an organic electroluminescent device OLED-1 containing compound 1, the manufacturing steps are as follows:

[0104] First, the alkali-free glass substrate was treated by using an ultrasonic cleaner and isopropyl alcohol to wash the alkali-free glass substrate for 15 minutes, and then UV ozone cleaning was performed in the air for 30 minutes. The treated substrate was vacuum-deposited with ITO / Ag / ITO 100nm as the anode, and the glass plate coated with the anode material was ultrasonically treated in a commercial cleaning agent, rinsed in deionized water, ultrasonically degreased in a mixed solvent of acetone: ethanol, baked in a clean environment until the water was completely removed, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam; the above-mentioned glass plate with the anode was placed in a vacuum chamber and evacuated to 1×10 -5 ~9×10 -3 Pa, vacuum evaporating a hole injection material (HI-1, 10nm, 2%) on the above anode layer to form a hole injection layer, the evaporation rate is 0.1-0.5nm / s; vacuum evaporating a hole transport material hole transport layer (HT-1, 30nm) on the hole injection layer to form a hole transport layer, the evaporation rate is 0.1-0.5nm / s; vacuum evaporating an electron blocking layer (EBL-1, 5nm) on the hole transport layer, the evaporation rate is 0.1-0.5nm / s; vacuum evaporating an organic light-emitting layer of the device (host material: doping material = Host-1: compound 1 (weight ratio 98:2, 30nm) on the electron blocking layer )); vacuum evaporate a hole blocking layer (HBL, 5nm) on the organic light-emitting layer at a rate of 0.1-0.5nm / s; vacuum evaporate the electron transport material of the device (compound ET-1:Liq=1:1, 30nm) on the hole blocking layer to form an electron transport layer at a rate of 0.1-0.5nm / s; vacuum evaporate Liq on the electron transport layer at a rate of 0.1-0.5nm / s as an electron injection layer, and co-evaporate Mg and Ag (weight ratio 10:1, 15nm) at a rate of 0.5-1nm / s to make a semi-transparent cathode, and finally encapsulate the light-emitting device OLED-1 with an epoxy resin adhesive in a nitrogen atmosphere.

[0105] The molecular structural formula of the relevant materials is as follows (particularly preferably selected from the following structures, but it does not mean that the present invention is limited to the following structures):

[0106]

[0107] Device Examples 2-10 refer to the above method, and replace the compound 1 used in Device Example 1 with compounds 26, 50, 65, 83, 91, 109, 120, 134, and 158 as doping materials to prepare corresponding organic electroluminescent devices OLED-2 to OLED-10.

[0108] Device Comparative Examples 1 to 3: This comparative example provides an organic electroluminescent device. The only difference between the preparation method of the organic electroluminescent device and the device embodiment is that the organic electroluminescent device uses existing comparative compounds a, b, and c to replace the doping material (compound 1) in the above device embodiment 1 for evaporation to prepare device comparative examples 1 to 3: devices OLED-a, OLED-b, and OLED-c. The chemical structural formulas of comparative compounds a, b, and c are:

[0109]

[0110] The driving voltage, luminous efficiency, FWHM and color of the organic electroluminescent devices obtained from the above device embodiments 1 to 10 and device comparative examples 1 to 3 were characterized at a brightness of 1000 (nits). The test results are shown in Table 1 below:

[0111] Table 1 Driving voltage, luminous efficiency, FWHM, luminous color and asymmetry factor of the organic electroluminescent devices of device control examples 1-3 and device examples 1-10

[0112]

[0113]

[0114] It can be seen from the above table that the organic electroluminescent device prepared by using the boron-containing compound containing 9,9′-bicarbazole provided by the present invention as the doping material of the light-emitting layer has a lower starting voltage, and the luminous efficiency and color purity are significantly improved.

[0115] 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 concept 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. A boron-containing compound containing 9,9'-bicarbazole, characterized in that: The bicarbazole structural unit with two nitrogen atoms directly connected forms an axial chiral center. A boron-containing multi-resonance structural unit is introduced into the first position of one of the carbazoles. This connection method increases the steric hindrance of the molecule. A 1,3,5-tri-tert-butylbenzene structural unit is introduced into the first position of the other carbazole to modify the periphery of the molecule. The boron-containing compound containing 9,9'-bicarbazole has the following design general formula: Wherein X1 and X2 are each independently selected from one of NR', S, and O; wherein Ar1 and Ar2 are the same or different and are independently selected from a substituted or unsubstituted six-membered aromatic ring, a substituted or unsubstituted six-membered heterocyclic ring, a substituted or unsubstituted five-membered heterocyclic ring, or a substituted or unsubstituted aromatic condensed ring unit; the aromatic condensed ring unit contains one or more of a six-membered aromatic ring, a six-membered heterocyclic ring, and a five-membered heterocyclic ring, and the aromatic condensed ring unit is connected to B, N, O, or S via a six-membered aromatic ring, a six-membered heterocyclic ring, or a five-membered heterocyclic ring; The R' is selected from a substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, and a substituted or unsubstituted C5-C60 heteroaromatic group.

2. The boron-containing compound containing 9,9'-bicarbazole according to claim 1, characterized in that The structure of the 9,9'-bicarbazole is as follows: The structure of D1 is: Wherein the D2 structure is selected from any one of the following structures: wherein Ar1 and Ar2 are the same or different and are independently selected from a substituted or unsubstituted six-membered aromatic ring, a substituted or unsubstituted six-membered heterocyclic ring, a substituted or unsubstituted five-membered heterocyclic ring, or a substituted or unsubstituted aromatic condensed ring unit; the aromatic condensed ring unit contains one or more of a six-membered aromatic ring, a six-membered heterocyclic ring, and a five-membered heterocyclic ring, and the aromatic condensed ring unit is connected to B, N, O, or S via a six-membered aromatic ring, a six-membered heterocyclic ring, or a five-membered heterocyclic ring; The R1, R2, R3 and R4 are each independently selected from a substituted or unsubstituted C1-C30 straight-chain hydrocarbon group, a substituted or unsubstituted C1-C30 branched hydrocarbon group, a substituted or unsubstituted C1-C30 halogenated alkyl group, a substituted or unsubstituted C3-C30 cycloalkyl group, a substituted or unsubstituted C6-C60 aromatic group, and a substituted or unsubstituted C5-C60 heteroaromatic group.

3. The boron-containing compound containing 9,9'-bicarbazole according to claim, characterized in that: The boron-containing compound containing 9,9'-bicarbazole is selected from any one of the following compounds:

4. A method for preparing a boron-containing compound containing 9,9'-bicarbazole as claimed in any one of claims 1 to 3, characterized in that: The method for preparing a boron-containing compound containing 9,9'-bicarbazole provides two different synthetic routes.

5. The method for preparing a boron-containing compound containing 9,9'-bicarbazole according to claim 4, characterized in that: Two different synthetic routes are provided. The first synthetic route specifically includes the following contents: In the above formula, X1, X2, Ar1, Ar2 are as defined in the above general formula; The specific preparation method includes: (1) Synthesis of intermediate a: At room temperature, [Ir(COD)(OMe)]2 and 4,4'-di-tert-butyl-2,2'-bipyridine are added to raw materials a and b, and then a certain amount of organic solvent is added to dissolve the raw materials, and the reaction is carried out in an inert gas protection environment for a period of time. After the reaction is completed, the reaction mixture is purified to obtain an intermediate a; (2) Synthesis of target compound: Add raw material c into a two-necked flask, dissolve it in acetone, then add strong oxidant potassium permanganate, reflux for a period of time in an inert gas protection environment, after the reaction is completed, cool the mother liquor to room temperature, then extract with an organic solvent and water, then dry with a desiccant, then distill off the excess solvent with reduced pressure, purify with a silica gel column, and finally dry to obtain intermediate b; Potassium carbonate and an organic solvent are added to intermediate b and intermediate a, a catalyst is added under an inert gas protection environment, and then the mixture is heated to reflux, reacts for a period of time, and then extracted, dried, and purified to finally obtain intermediate c. Potassium carbonate and an organic solvent are then added to intermediate c and raw material d, a catalyst is added under an inert gas protection environment, and then the mixture is heated to reflux, reacts for a period of time, and then extracted, dried, and purified to obtain the target compound.

6. The method for preparing a boron-containing compound containing 9,9'-bicarbazole according to claim 5, wherein the first synthetic route is characterized by: The organic solvent used in the synthesis of intermediate a in (1) is one or more of tetrahydrofuran, 1,2-dichloroethane, chloroform, toluene, chlorobenzene, 1,4-dioxane, N,N-dimethylformamide, and dimethyl sulfoxide; the inert gas used is one or more of nitrogen and argon; the reaction time is 12 to 30 hours; the molar ratio of raw material a to raw material b is 1:(1-1.8); the inert gas used in the synthesis of intermediate b in (2) the synthesis of the target compound is one or more of nitrogen and argon; the desiccant is anhydrous sodium sulfate, anhydrous magnesium sulfate, etc.; the reaction temperature is 40 to 140°C; the reaction time is 4 to 10 hours; the catalyst used in the synthesis of the target compound in (2) is: Pd(PPh3) 4、 One or more of palladium acetate and Pd(dba)2; the organic solvent used is one or more of tetrahydrofuran, dichloromethane, 1,2-dichloroethane, chloroform, toluene and chlorobenzene; the inert gas used is one or more of nitrogen and argon; the desiccant is anhydrous sodium sulfate, anhydrous magnesium sulfate, etc.; the reaction temperature is 40-140°C; the reaction time is 8-28 hours.

7. The method for preparing a boron-containing compound containing 9,9'-bicarbazole according to claim 4, characterized in that: There are two different synthetic routes. The second synthetic route specifically includes the following: In the above formula, X1, X2, Ar1, Ar2 are as defined in the above general formula; The specific preparation method includes: (1) Synthesis of intermediate a: The same as synthetic route 1; (2) Synthesis of target compound: Strong base potassium carbonate and an organic solvent are added to the raw material c and the intermediate a, a catalyst is added under an inert gas protection environment, and then the mixture is heated to reflux, reacted for a period of time, and then extracted, dried, and purified to finally obtain an intermediate d. The raw material c and the intermediate d are added to a two-necked flask, dissolved in acetone, and then a strong oxidant potassium permanganate is added, and refluxed for a period of time under an inert gas protection environment. After the reaction is completed, the mother liquor is cooled to room temperature, and then extracted, dried, and purified to finally obtain an intermediate e. Potassium carbonate and an organic solvent are added to the intermediate e and the raw material d, and a catalyst is added under an inert gas protection environment. Then the mixture is heated to reflux, reacted for a period of time, and then extracted, dried, and purified to finally obtain the target compound.

8. The method for preparing a boron-containing compound containing 9,9'-bicarbazole according to claim 7, characterized in that: The second synthetic route, the catalyst used in the synthesis of intermediate d in the synthesis of the target compound (2) and the synthesis of the target compound is: one or more of Pd(PPh3)4, palladium acetate, Pd(dba)2; the organic solvent used is one or more of tetrahydrofuran, dichloromethane, 1,2-dichloroethane, chloroform, toluene, chlorobenzene; the inert gas used is one or more of nitrogen and argon; the desiccant is anhydrous sodium sulfate, anhydrous magnesium sulfate, etc.; the reaction temperature is 40-140°C; the reaction time is 8-28 hours; the molar ratio of raw material c to intermediate a is 1:(0.3-1.8); the inert gas used in the synthesis of intermediate e in the synthesis of the target compound (2) is one or more of nitrogen and argon; the desiccant is anhydrous sodium sulfate, anhydrous magnesium sulfate, etc.; the reaction temperature is 40-140°C; the reaction time is 4-10 hours.

9. A use of a boron-containing compound containing 9,9'-bicarbazole as claimed in any one of claim 1, characterized in that: The application of the boron-containing compound containing 9,9'-bicarbazole is as a functional material in organic electronic devices, and the organic electronic devices include organic light-emitting diodes, lighting elements, organic thin-film transistors, organic field-effect light-emitting transistors, organic field-effect transistors, organic lasers, organic thin-film solar cells, information tags, electronic artificial skin sheets, sheet-type scanners or electronic paper.

10. The use of a boron-containing compound containing 9,9'-bicarbazole according to claim 9, characterized in that: The compound is used as a light-emitting layer or a transport layer material in an organic electroluminescent device; the organic electroluminescent device includes an organic light-emitting diode, an organic field-effect light-emitting transistor and an organic laser.

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