Boron-nitrogen heterocyclic compound, preparation method thereof and organic electroluminescent device

Abstract

The invention provides a boron-nitrogen heterocyclic compound, a preparation method thereof and an organic electroluminescent device, and relates to the technical field of organic luminescent materials. According to the boron-nitrogen heterocyclic compound, on the core basis of a traditional multiple resonance type thermally activated delayed fluorescent material, an aromatic hydrocarbon unit, namely a spirofluorene unit, with a torsion structure is introduced to the periphery, and on the premise that narrow-band light emission is kept, the photoelectric property of the material can be further improved; the preparation of an efficient narrow-band OLED (Organic Light Emitting Diode) device is remarkably enhanced; the electroluminescent peak position of the boron-nitrogen heterocyclic compound is 470-490 nm, and the boron-nitrogen heterocyclic compound is an organic blue-light guest material. The boron-nitrogen heterocyclic compound has a narrow emission spectrum, good thermal stability, a fast radiation attenuation rate, an efficient energy transfer channel and a high photoluminescence quantum yield, and the external quantum efficiency of the electroluminescent device prepared from the boron-nitrogen heterocyclic compound is obviously improved on the premise that the FWHM value is effectively controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of organic light-emitting materials, and in particular, to a boron-nitrogen heterocyclic compound, a preparation method thereof, and an organic electroluminescent device. Background Art

[0002] The rapid development of the global digital economy has driven the demand for high-definition display technologies. In particular, the standard for ultra-high-definition televisions (BT.2020) has put forward higher requirements for display quality. Against this background, the limitations of traditional fluorescent emission devices have emerged. In particular, commercial materials used in organic electroluminescent devices (OLEDs) often produce a full width at half maximum (FWHM) of about 50 nm, which has an adverse impact on aspects such as the color purity, efficiency, resolution, lifespan, and energy consumption of the light-emitting devices. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art, the present invention provides a boron-nitrogen heterocyclic compound, a preparation method thereof, and an organic electroluminescent device. The boron-nitrogen heterocyclic compound provided by the present invention has a narrow emission spectrum, good thermal stability, a fast radiative decay rate, an efficient energy transfer channel, and a high photoluminescence quantum yield.

[0004] The specific technical solution of the present invention is as follows: In a first aspect, the present invention provides a boron-nitrogen heterocyclic compound having a structure shown in Formula I or Formula II:

[0005] Wherein, R is selected from at least one of an alkyl group, fluorine, bromine, chlorine, a cyano group, an aromatic ring, and a nitrogen-containing aromatic ring.

[0006] The boron-nitrogen heterocyclic compound provided by the present invention is based on an MR-TADF heterocyclic compound, and a large steric hindrance spiro unit is introduced at the end group to achieve intermolecular barrier, reduce intermolecular π-π stacking, inhibit concentration quenching, and at the same time improve the energy transfer rate. On the premise of maintaining its narrow-band luminescence, the optoelectronic properties of the material can be further improved, which has a significant enhancing effect on the preparation of efficient narrow-band OLED devices.

[0007] In a possible implementation manner, the R is any one of the structures of R1-R12: .

[0008] By changing the modifying groups on the boron-nitrogen heterocyclic compound, its physical and chemical properties can be further improved, making it have more excellent properties in organic semiconductor devices.

[0009] In a possible implementation manner, the boron-nitrogen heterocyclic compound is any one of the compounds of BNS1-BNS24: 。

[0010] In a possible implementation manner, the synthesis route of the BNS1 is as follows: 。

[0011] In a possible implementation manner, the synthesis route of the BNS13 is as follows: 。

[0012] In a second aspect, the present invention further provides a preparation method of the above-mentioned boron-nitrogen heterocyclic compound, including the following steps: S1. 1,3-Dibromo-5-methylbenzene and 2,4,6-trimethylaniline undergo a Buchwald-Hartwig coupling reaction to obtain a first intermediate, and the structure of the first intermediate is as shown in Formula III:

[0013] S2. The first intermediate prepared in step S1 and 9,9'-spirobifluorene bromide undergo a Buchwald-Hartwig coupling reaction to obtain a second intermediate, and the structure of the second intermediate is as shown in Formula IV or Formula V:

[0014] S3. Under a protective atmosphere, the second intermediate prepared in step S2 reacts with boron tribromide in ortho-dichlorobenzene to obtain a boron-nitrogen heterocyclic compound.

[0015] The preparation method of the boron-nitrogen heterocyclic compound provided by the present invention synthesizes a spiro-based narrow emission spectrum boron-nitrogen heterocyclic compound via a series of Hartwig-Buchwald reactions and then through a "one-pot method", and the preparation method is simple and efficient.

[0016] Furthermore, the molar ratio of 1,3-dibromo-5-methylbenzene to 2,4,6-trimethylaniline in step S1 is 1:(2 - 2.5). By controlling the molar ratio of 1,3-dibromo-5-methylbenzene to 2,4,6-trimethylaniline, it is beneficial to improve the yield of the first intermediate.

[0017] Furthermore, the catalyst for the Buchwald-Hartwig coupling reaction in step S1 is Pd 2 (dba) 3 、t-Bu 3 PHBF 4 and t-BuONa, and the Pd 2 (dba) 3 、the t-Bu 3 PHBF 4The molar ratio with the t-BuONa is 2:5:1.5. By using the above catalyst combination and optimizing the molar ratio of Pd 2 (dba) 3 , t-Bu 3 PHBF 4 and t-BuONa, the reaction rate of the Buchwald-Hartwig coupling reaction in step S1 can be further increased.

[0018] Furthermore, the temperature of the Buchwald-Hartwig coupling reaction in step S1 is 100 - 110 °C and the time is more than 8 h. By further optimizing the temperature and time of the Buchwald-Hartwig coupling reaction in step S1, it is beneficial to improve the purity and yield of the first intermediate.

[0019] Furthermore, the molar ratio of the first intermediate to the bromo-9,9'-spirobifluorene in step S2 is 1:2. By controlling the molar ratio of the first intermediate to the bromo-9,9'-spirobifluorene, it is beneficial to improve the yield of the second intermediate.

[0020] Furthermore, the catalyst for the Buchwald-Hartwig coupling reaction in step S2 is Pd 2 (dba) 3 , X-Phos and t-BuONa, and the molar ratio of the Pd 2 (dba) 3 , the X-Phos and the t-BuONa is 50:200:6. By using the above catalyst combination and optimizing the molar ratio of Pd 2 (dba) 3 , X-Phos and t-BuONa, the reaction rate of the Buchwald-Hartwig coupling reaction in step S2 can be further increased.

[0021] Furthermore, the temperature of the Buchwald-Hartwig coupling reaction in step S2 is 110 - 120 °C and the time is more than 8 h. By further optimizing the temperature and time of the Buchwald-Hartwig coupling reaction in step S2, it is beneficial to improve the purity and yield of the second intermediate.

[0022] In a possible implementation, the solvent for the Buchwald-Hartwig coupling reactions in steps S1 and S2 is toluene.

[0023] In a possible implementation, the molar ratio of the second intermediate to the boron tribromide in step S3 is 1:4. By controlling the molar ratio of the second intermediate to the boron tribromide, it is beneficial to improve the yield of the boron-nitrogen heterocyclic compound.

[0024] In a possible implementation, the temperature of the reaction in step S3 is 200 - 210 °C, and the time is more than 24 h. By further optimizing the temperature and time of the reaction in step S3, it is beneficial to improve the purity and yield of the boron-nitrogen heterocyclic compound.

[0025] In a possible implementation, the gas of the protective atmosphere in step S3 is argon.

[0026] In a third aspect, the present invention also provides an organic electroluminescent device, and the light-emitting layer material composition of the organic electroluminescent device includes the above-mentioned boron-nitrogen heterocyclic compound.

[0027] In a possible implementation, the organic electroluminescent device includes, from bottom to top in sequence, a transparent substrate, an ITO conductive glass anode, a hole injection layer HATCN, hole transport layers TAPC and TCTA, an exciton blocking layer mCP, a light-emitting layer, an exciton blocking layer PPF, an electron transport layer TmPyPb, an electron injection layer LiF, and a cathode layer Al; the light-emitting layer is composed of the above-mentioned boron-nitrogen heterocyclic compound as a doped guest material, m-MDBA-DI and mCPBC as host materials, and the mass ratio of the doped guest material in the light-emitting layer is 2 - 5%, the mass ratio of m-MDBA-DI is 15 - 20%, and the structural formulas of the HATCN, TAPC, TCTA, mCP, PPF, TmPyPb, m-MDBA-DI, and mCPBC are shown as follows: 。

[0028] On the basis of conforming to common knowledge in the art, the above-mentioned various embodiments can be combined arbitrarily.

[0029] The reagents and raw materials used in the present invention are all commercially available.

[0030] The positive and progressive effects of the present invention are as follows: The boron-nitrogen heterocyclic compound provided in the present invention is a thermally activated delayed fluorescence compound containing boron-nitrogen heterocycles with a spirofluorene structure. Based on the core of traditional multiple resonance-type thermally activated delayed fluorescence (MR-TADF) materials, an aromatic unit with a twisted structure - the spirofluorene unit - is introduced at the periphery. On the premise of maintaining its narrow-band emission, the optoelectronic properties of the material can be further improved, which has a significant enhancing effect on the preparation of efficient narrow-band OLED devices; the electroluminescence peak position of the boron-nitrogen heterocyclic compound is at 470 - 490 nm, and it is a type of organic blue-light guest material; the boron-nitrogen heterocyclic compound has a narrow emission spectrum, good thermal stability, fast radiative decay rate, efficient energy transfer channels, and high photoluminescence quantum yield (PLQY). For the electroluminescent device prepared with the boron-nitrogen heterocyclic compound, on the premise that the FWHM value is effectively controlled, the external quantum efficiency is significantly improved. Description of the Drawings

[0031] Figure 1 Absorption, emission, and phosphorescence spectra of the compound prepared in Example 1 in toluene solution.

[0032] Figure 2 Absorption, emission, and phosphorescence spectra of the compound prepared in Example 2 in toluene solution.

[0033] Figure 3 Thermogravimetric analysis and differential scanning calorimetry curves of the compound prepared in Example 1.

[0034] Figure 4 Thermogravimetric analysis and differential scanning calorimetry curves of the compound prepared in Example 2.

[0035] Figure 5 Current density-voltage-luminance curve of the organic electroluminescent device prepared in Example 3.

[0036] Figure 6 Current density-voltage-luminance curve of the organic electroluminescent device prepared in Example 4.

[0037] Figure 7 External quantum efficiency-luminance curve of the organic electroluminescent device prepared in Example 3.

[0038] Figure 8 External quantum efficiency-luminance curve of the organic electroluminescent device prepared in Example 4.

[0039] Figure 9 Emission spectrum of the organic electroluminescent device prepared in Example 3.

[0040] Figure 10 Emission spectrum of the organic electroluminescent device prepared in Example 4. Detailed implementation manners

[0041] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of specific embodiments of the present invention is provided. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the protection scope of the claims of the present invention.

[0042] It should be noted that the endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0043] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with commonly understood meanings are defined herein for the purpose of clarification or convenient reference. Such definitions herein should not be construed as indicating a significant difference from the conventional understanding in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise specified, the use of commercially available kits, reagents, and instruments is carried out according to the protocols and parameters given by the manufacturers.

[0044] Example 1 This example provides a boron-nitrogen heterocyclic compound, the structural formula of which is shown as BNS1, and its synthesis route is as follows:

[0045] It is specifically prepared by the following preparation method: S1. In a 100 mL three-necked round-bottom reaction flask filled with argon, 1,3-di-bromo-5-methylbenzene (2.49 g, 10.0 mmol), 2,4,6-trimethylaniline (2.97 g, 22.0 mmol), Pd 2 (dba) 3 (0.18 g, 0.02 mol), t-Bu 3 PHBF 4A mixture of (0.15 g, 0.05 mol), t-BuONa (1.44 g, 15.0 mmol) and 50 mL of toluene was stirred overnight at 110 °C. The cooled mixture was extracted with dichloromethane and water. After removing the organic solvent, the remaining solid was further separated and purified by silica gel column chromatography (eluted with petroleum ether / dichloromethane) to obtain 4.91 g of a pure white solid, the first intermediate, and the yield of the first intermediate was 90%; The 1H NMR spectrum of the first intermediate is as follows: 1 1H NMR (400 MHz, CDCl 3 ) δ 6.92 (s, 4H), 5.71 (s, 2H), 5.52 (s, 1H), 4.91 (s, 2H), 2.31 (s, 6H), 2.18 (s, 13H), 2.10 (s, 4H); The time-of-flight mass spectrum (ESI+) of the first intermediate: calculated value: 359.5290; measured value: 359.2469; S2. In a 100 mL three-necked round-bottom reaction flask filled with argon, the first intermediate (5.00 g, 20.0 mmol), 2-bromo-spirofluorene (12.00 g, 40.0 mmol), Pd 2 (dba) 3 (0.58 g, 0.5 mol), X-Phos (0.96 g, 2.0 mol), t-BuONa (5.76 g, 60.0 mmol) and 80 mL of toluene were stirred overnight at 120 °C. The cooled mixture was extracted with dichloromethane and water. After removing the organic solvent, the remaining solid was further separated and purified by silica gel column chromatography (eluted with petroleum ether / dichloromethane) to obtain 7.52 g of a pure white solid, the second intermediate, and the yield of the second intermediate was 74%; The 1H NMR spectrum of the second intermediate is as follows: 1 1H NMR (400 MHz, CDCl 3)δ7.56 (d, J = 7.4 Hz, 2H), 7.44 (d, J = 8.3 Hz,2H), 7.34 (d, J = 7.3 Hz, 2H), 7.27 (d, J = 7.3 Hz, 1H), 7.25 (s, 1H), 7.20(t, J = 7.3 Hz, 2H), 7.08 (d, J = 1.8 Hz, 2H), 6.88 (s, 4H), 6.77 (dd, J =8.3, 1.9 Hz, 2H), 6.67 (s, 1H), 6.36 (s, 2H), 2.31 (s, 6H), 2.13 (s, 3H),2.01 (s, 12H), 1.37 (s, 12H); Time-of-flight mass spectrum (ESI+) of the second intermediate: Calculated: 743.0510; Measured: 743.4329; S3. In a 120 mL argon-sealed pressure-resistant tube, add the second intermediate (3.5 g, 5.0 mmol) and 30 mL of o-dichlorobenzene (o-DCB), then add boron tribromide (5.00 g, 20.0 mmol), and then stir and react at 200 °C for 24 h. After cooling to room temperature, slowly add an alcohol reagent (5.0 mL) to quench the reaction in an ice bath; the organic solvent is concentrated under vacuum conditions, and the residual solid is further separated and purified by a silica gel chromatography column (eluted with petroleum ether / dichloromethane) to obtain 2.62 g of pure bright yellow solid boron-nitrogen heterocyclic compound BNS1, and the yield of boron-nitrogen heterocyclic compound BNS1 is 70%; The 1H NMR spectrum of boron-nitrogen heterocyclic compound BNS1 is as follows: 1 H NMR (400 MHz, CDCl 3 )δ9.50 (s, 2H), 8.12 (d, J = 7.6 Hz, 2H), 7.74(d, J = 7.6 Hz, 4H), 7.47 (t, J = 7.4 Hz, 2H), 7.32 (t, J = 7.4 Hz, 4H), 7.09(t, J = 7.2 Hz, 6H), 6.82 (d, J = 9.7 Hz, 8H), 6.71 (d, J = 7.6 Hz, 2H), 6.06(s, 2H), 5.74 (s, 2H), 2.27 (s, 6H), 2.06 (s, 3H), 1.59 (s, 12H). 13C NMR(101 MHz, CDCl 3)δ152.92, 149.67, 148.62, 146.49, 145.29, 143.39, 142.27,141.53, 137.67, 136.68, 136.37, 134.29, 129.85, 127.86, 127.59, 127.38,126.78, 125.90, 124.04, 123.94, 119.74, 119.50, 111.01, 104.74, 66.31, 23.16,21.08, 17.18; Time-of-flight mass spectrum (ESI+) of boron-nitrogen heterocyclic compound BNS1: Calculated value: 995.0890; Measured value: 995.4581.

[0046] Example 2 This example provides a boron-nitrogen heterocyclic compound, the structural formula of which is shown as BNS13, and its synthesis route is as follows:

[0047] It is prepared by the following preparation method: S1. In a 100 mL three-necked round-bottom reaction flask filled with argon, a mixture of 1,3-dibromo-5-methylbenzene (2.49 g, 10.0 mmol), 2,4,6-trimethylaniline (2.97 g, 22.0 mmol), Pd 2 (dba) 3 (0.18 g, 0.02 mol), t-Bu 3 PHBF 4 (0.15 g, 0.05 mol), t-BuONa (1.44 g, 15.0 mmol) and 50 mL of toluene was stirred overnight at 110 °C. After cooling, the mixture was extracted with dichloromethane and water. After removing the organic solvent, the remaining solid was further separated and purified by a silica gel column chromatography (eluted with petroleum ether / dichloromethane) to obtain 4.91 g of a pure white solid first intermediate, and the yield of the first intermediate was 90%; The 1H NMR spectrum of the first intermediate is as follows: 1 H NMR (400 MHz, CDCl 3 )δ6.92 (s, 4H), 5.71 (s, 2H), 5.52 (s, 1H), 4.91(s, 2H), 2.31 (s, 6H), 2.18 (s, 13H), 2.10 (s, 4H); Time-of-flight mass spectrum (ESI+) of the first intermediate: Calculated value: 359.5290; Measured value: 359.2469; S2. In a 100 mL three-necked round-bottom reaction flask filled with argon, the first intermediate (5.00 g, 20.0 mmol), 3-bromo-spirofluorene (12.00 g, 40.0 mmol), Pd 2 (dba) 3 (0.58 g, 0.5 mmol), X-Phos (0.96 g, 2.0 mmol), t-BuONa (5.76 g, 60.0 mmol) and 80 mL of toluene were stirred overnight at 120 °C. The cooled mixture was extracted with dichloromethane and water. After removing the organic solvent, the remaining solid was further separated and purified by silica gel column chromatography (eluted with petroleum ether / dichloromethane) to obtain 7.75 g of a pure white solid second intermediate, and the yield of the second intermediate was 77%; The 1H NMR spectrum of the second intermediate is as follows: 1 1H NMR (400 MHz, CDCl 3 ) δ 7.82 (t, J = 7.0 Hz, 4H), 7.66 (t, J = 7.9 Hz, 2H), 7.49 (d, J = 12.8 Hz, 2H), 7.38–7.28 (m, 4H), 7.22 (t, J = 7.4 Hz, 1H), 7.16–7.00 (m, 6H), 6.88 (d, J = 26.3 Hz, 5H), 6.79–6.55 (m, 8H), 6.47 (dd, J = 16.9, 8.3 Hz, 2H), 6.35 (s, 1H), 6.10 (d, J = 21.6 Hz, 1H), 5.88 (s, 1H), 2.24–2.13 (m, 12H), 2.04 (s, 9H); Time-of-flight mass spectrum (ESI+) of the second intermediate: Calculated value: 987.3030; Measured value 987.4664; S3. In a 120 mL argon-sealed pressure-resistant tube, add the second intermediate (3.5 g, 5.0 mmol) and 30 mL of o-dichlorobenzene (o-DCB), then add boron tribromide (5.00 g, 20.0 mmol), and then stir and react at 200 °C for 24 h. After cooling to room temperature, slowly add an alcohol reagent (5.0 mL) to quench the reaction in an ice bath; the organic solvent is concentrated under vacuum conditions, and the residual solid is further separated and purified by a silica gel chromatography column (eluted with petroleum ether / dichloromethane) to obtain 2.75 g of pure bright yellow solid boron-nitrogen heterocyclic compound BNS13, and the yield of boron-nitrogen heterocyclic compound BNS13 is 55%; The nuclear magnetic resonance hydrogen spectrum of boron-nitrogen heterocyclic compound BNS13 is as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.84 (d, J = 6.6 Hz, 6H), 7.52 (d, J = 7.5Hz, 2H), 7.36 (t, J = 7.4 Hz, 4H), 7.20 (d, J = 10.9 Hz, 6H), 7.04 – 6.97 (m,4H), 6.94 (t, J = 7.3 Hz, 4H), 6.55 (dd, J = 15.5, 7.5 Hz, 6H), 5.89 (s, 2H),2.51 (s, 6H), 2.17 (s, 3H), 1.89 (s, 12H). 13C NMR (101 MHz, CDCl 3 ) δ 151.10,149.22, 146.34, 145.40, 145.06, 143.30, 141.11, 138.79, 138.07, 137.32,137.24, 130.42, 130.35, 129.78, 128.32, 127.39, 127.17, 127.10, 124.84,123.80, 123.73, 120.22, 106.07, 104.33, 65.49, 23.19, 21.37, 17.63; The time-of-flight mass spectrum of boron-nitrogen heterocyclic compound BNS13 (ESI+): Calculated value: 995.0890; Measured value: 995.4576.

[0048] Example 3

[0049] This example provides an organic electroluminescent device with the following structure: Glass substrate / Indium tin oxide / HATCN (5 nm) / TAPC (50 nm) / TCTA (5 nm) / mCP (50 nm) / 5 wt% Compound BNS1: 20 wt% m-MDBA-I: mCPBC (30 nm) / PPF (5 nm) / TmPyPB (40 nm) / Lithium fluoride (1 nm) / Aluminum (150 nm). Among them, indium tin oxide is the conductive anode, HATCN is the hole injection layer, TAPC and TCTA are hole transport layers, mCP and PPF are exciton blocking layers, the light-emitting layer is 5 wt% Compound BNS1: 20 wt% m-MDBA-DI: mCPBC, TmPyPB is the electron transport layer, lithium fluoride is the electron injection layer, and aluminum is used as the cathode; the values in parentheses are the thicknesses of each layer. The structural formulas of HATCN, TAPC, TCTA, mCP, PPF, TmPyPb, m-MDBA-DI, and mCPBC are shown as follows:

[0050] It is prepared by the following preparation method: S1. The transparent conductive indium tin oxide glass substrate is ultrasonically cleaned with a micron-level semiconductor special detergent, deionized water, acetone, and isopropanol for 15 minutes in sequence to remove the dirt on the substrate surface, and then placed in an incubator at 80 °C for drying for later use; S2. The indium tin oxide glass substrate obtained in step S1 is treated with ultraviolet-ozone for 30 minutes to further remove the organic pollutants attached to the surface; S3. On the indium tin oxide glass substrate obtained in step S2, HATCN, TAPC, TCTA, mCP, Compound BNS1, m-MDBA-DI, mCPBC, TmPyPB, lithium fluoride, and aluminum are sequentially deposited by vacuum thermal evaporation to obtain an organic electroluminescent device.

[0051] Example 4

[0052] This example provides an organic electroluminescent device, and its structure is as follows: Glass substrate / Indium tin oxide / HATCN (5 nm) / TAPC (50 nm) / TCTA (5 nm) / mCP (50 nm) / 5 wt% Compound BNS13: 20 wt% m-MDBA-DI: mCPBC (30 nm) / PPF (5 nm) / TmPyPB (40 nm) / Lithium fluoride (1 nm) / Aluminum (150 nm). Among them, indium tin oxide is the conductive anode, HATCN is the hole injection layer, TAPC and TCTA are hole transport layers, mCP and PPF are exciton blocking layers, the light-emitting layer is 5 wt% Compound BNS13: 20 wt% m-MDBA-DI: mCPBC, TmPyPB is the electron transport layer, lithium fluoride is the electron injection layer, and aluminum is used as the cathode; the values in parentheses are the thicknesses of each layer. The structural formulas of HATCN, TAPC, TCTA, mCP, PPF, TmPyPb, m-MDBA-DI, and mCPBC are shown as follows:

[0053] It is prepared by the following preparation method: S1. The transparent conductive indium tin oxide glass substrate is ultrasonically cleaned with a micron-level semiconductor special detergent, deionized water, acetone, and isopropanol for 15 minutes in sequence to remove the dirt on the substrate surface, and then placed in an incubator at 80 °C for drying for later use; S2. The indium tin oxide glass substrate obtained in step S1 is treated with ultraviolet-ozone for 30 minutes to further remove the organic pollutants attached to the surface; S3. On the indium tin oxide glass substrate obtained in step S2, HATCN, TAPC, TCTA, mCP, Compound BNS13, m-MDBA-DI, mCPBC, PPF, TmPyPB, lithium fluoride, and aluminum are sequentially deposited by vacuum thermal evaporation to obtain an organic electroluminescent device.

[0054] Test effect description: Figure 1 Absorption, emission spectra, and phosphorescence spectra of the compound prepared in Example 1 in toluene solution. As can be seen from the figure, the electroluminescence peak position of Compound BNS1 is 482 nm, and the FWHM value is 22 nm, indicating that Compound BNS1 is a narrow-spectrum blue light-emitting material.

[0055] Figure 2 Absorption, emission spectra, and phosphorescence spectra of the compound prepared in Example 2 in toluene solution. As can be seen from the figure, the electroluminescence peak position of Compound BNS13 is 488 nm, and the FWHM value is 22 nm, indicating that Compound BNS13 is a narrow-spectrum blue light-emitting material.

[0056] Figure 3Thermogravimetric analysis and differential scanning calorimetry curves of the compound obtained in Example 1. As can be seen from the figure, the compound BNS1 has good thermal stability below 470 °C.

[0057] Figure 4 Thermogravimetric analysis and differential scanning calorimetry curves of the compound obtained in Example 2. As can be seen from the figure, the compound BNS13 also has good thermal stability below 470 °C.

[0058] Figure 5 Current density-voltage-luminance curve of the organic light-emitting device obtained in Example 3. As can be seen from the figure, the luminance of the organic light-emitting device using the compound BNS1 can reach 29350 cd m -2 .

[0059] Figure 6 Current density-voltage-luminance curve of the organic light-emitting device obtained in Example 4. As can be seen from the figure, the luminance of the organic light-emitting device using the compound BNS13 can reach 35650 cd m -2 .

[0060] Figure 7 External quantum efficiency-luminance curve of the organic light-emitting device obtained in Example 3. As can be seen from the figure, the external quantum efficiency of the organic light-emitting device using the compound BNS1 can reach 34.6%.

[0061] Figure 8 External quantum efficiency-luminance curve of the organic light-emitting device obtained in Example 4. As can be seen from the figure, the external quantum efficiency of the organic light-emitting device using the compound BNS13 can reach 33.3%.

[0062] Figure 9 Emission spectrum of the organic light-emitting device obtained in Example 3. As can be seen from the figure, the emission peak of the organic light-emitting device using the compound BNS13 is located at 482 nm, and the full width at half maximum is 26 nm..

[0063] Figure 10 Emission spectrum of the organic light-emitting device obtained in Example 4. As can be seen from the figure, the emission peak of the organic light-emitting device using the compound BNS13 is located at 492 nm, and the full width at half maximum is 28 nm.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A boron-nitrogen heterocyclic compound, characterized in that Having a structure as shown in Formula I or Formula II: Wherein, R is selected from at least one of an alkyl group, a fluorine group, a bromine group, a chlorine group, a cyano group, an aromatic ring, and a nitrogen-containing aromatic ring.

2. The boron nitrogen heterocyclic compound according to claim 1, characterized in that The R is any structure among R1-R12: 。 3. The boron nitrogen heterocyclic compound according to claim 1, characterized in that The boron nitrogen heterocyclic compound is any one of BNS1-BNS24: 。 4. The boron nitrogen heterocyclic compound according to claim 3, characterized in that The synthetic route of BNS1 is as follows: The synthetic route of BNS13 is as follows: 。 5. A method for preparing the boron nitrogen heterocyclic compound according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, 1,3-dibromo-5-methylbenzene and 2,4,6-trimethylaniline are subjected to a Buchwald-Hartwig coupling reaction to obtain a first intermediate, the structure of which is shown in Formula III: S2. The first intermediate prepared in step S1 and bromo-9,9'-spirobifluorene are subjected to a Buchwald-Hartwig coupling reaction to obtain a second intermediate, wherein the structure of the second intermediate is shown in Formula IV or Formula V: S3. Under a protective atmosphere, the second intermediate obtained in step S2 reacts with boron tribromide in o-dichlorobenzene to obtain a boron nitrogen heterocyclic compound.

6. The method for preparing the boron nitrogen heterocyclic compound according to claim 5, characterized in that: The molar ratio of 1,3-dibromo-5-methylbenzene to 2,4,6-trimethylaniline in step S1 is 1:(2-2.5); And / or, the catalyst for the Buchwald-Hartwig coupling reaction in step S1 is Pd2(dba)3, t-Bu3PHBF4 and t-BuONa, and the molar ratio of Pd2(dba)3, t-Bu3PHBF4 and t-BuONa is 2:5:1.5; And / or, the temperature of the Buchwald-Hartwig coupling reaction in step S1 is 100-110° C. and the time is more than 8 h.

7. The method for preparing a boron-nitrogen heterocyclic compound according to claim 5, characterized in that: Step S2: the molar ratio of the first intermediate to the bromo-9,9'-spirobifluorene is 1:2; And / or, the catalyst for the Buchwald-Hartwig coupling reaction in step S2 is Pd2(dba)3, X-Phos and t-BuONa, and the molar ratio of Pd2(dba)3, X-Phos and t-BuONa is 50:200:6; And / or, the temperature of the Buchwald-Hartwig coupling reaction in step S2 is 110-120° C. and the time is more than 8 h.

8. The method for preparing the boron nitrogen heterocyclic compound according to claim 5, characterized in that: Step S3: the molar ratio of the second intermediate to the boron tribromide is 1:4; And / or, the reaction temperature in step S3 is 200-210°C and the reaction time is more than 24 hours; And / or, the protective atmosphere gas in step S3 is argon.

9. An organic electroluminescent device, characterized in that: The material composition of the light-emitting layer of the organic electroluminescent device includes the boron-nitrogen heterocyclic compound according to any one of claims 1 to 4.

10. The organic electroluminescent device according to claim 9, characterized in that: The organic electroluminescent device comprises, from bottom to top, a transparent substrate, an ITO conductive glass anode, a hole injection layer HATCN, hole transport layers TAPC and TCTA, an exciton blocking layer mCP, a light-emitting layer, an exciton blocking layer PPF, an electron transport layer TmPyPb, an electron injection layer LiF and a cathode layer Al; the light-emitting layer is composed of the boron nitrogen heterocyclic compound described in any one of claims 1 to 4 as a doped guest material, and m-MDBA-DI and mCPBC as a main material, the mass proportion of the doped guest material in the light-emitting layer is 2-5%, and the mass proportion of the m-MDBA-DI is 15-20%, and the structural formulas of the HATCN, the TAPC, the TCTA, the mCP, the PPF, the TmPyPb, the m-MDBA-DI and the mCPBC are as follows: 。

Images