A boron nitride compound, an organic electroluminescent device

Abstract

The present invention belongs to the technical field of organic optoelectronic materials, and more specifically, relates to a boron nitride compound and an organic electroluminescent device. The boron nitride compound provided by the present invention has a structure shown in formula (1) or (2), and has the advantages of simple synthesis method, short synthesis period, reproducibility of multiple syntheses, etc. Moreover, the ΔE<subgt;ST< / subgt; of the above boron nitride compound is small, the PLQY is high, it has good solubility, excellent film-forming property and stable film morphology, and can be used as a solution-processable thermally activated delayed fluorescence material, which is suitable for preparing OLED devices by solution method. By applying the above boron nitride compound to an organic electroluminescent device through a solution processing method, the present invention can achieve a high external quantum efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of organic optoelectronic materials, and more particularly, to a boron nitride compound and an organic light-emitting device. Background Art

[0002] Since C.W. Tang et al. first reported ultrathin multilayer organic light-emitting diodes (OLEDs) in 1987, OLEDs have received extensive attention in both academic and industrial fields and have been successfully commercialized. As the third-generation organic light-emitting diode (OLED) materials, thermally activated delayed fluorescence (TADF) materials have attracted wide attention in the academic and industrial fields because they do not contain expensive noble metals and can make full use of the characteristics of singlet and triplet excitons. Although significant progress has been made in the research of TADF materials and devices, new TADF materials are still urgently needed to be developed, especially the development and design of highly efficient TADF materials.

[0003] With the progress of people's understanding of their molecular design criteria and photophysical principles, the maximum external quantum efficiency (EQE) of TADF-OLED devices fabricated by vacuum evaporation has exceeded 40%, approaching the level of phosphorescent devices. However, the equipment used for vacuum evaporation is complex, the equipment investment and maintenance costs are high, and the utilization rate of organic materials is low, etc., which increase the manufacturing cost and complexity of OLED devices and seriously affect the popularization and application of OLED displays. Solution processing techniques such as spin coating, inkjet printing, roll-to-roll, gravure printing, and screen printing, as an effective alternative strategy, have received extensive attention because of their high material utilization rate, simple manufacturing process, low equipment investment cost, and suitability for large-scale production. However, the molecular requirements for TADF materials by solution processing are very strict. Their molecules not only need to have a small ΔE ST and a high fluorescence quantum yield (PLQY), but also need to have good solubility and film-forming ability to meet their solution processability.

[0004] Small molecule TADF materials have advantages such as a definite molecular structure, easy synthesis and purification, and a monodisperse molecular weight, making them promising solution-processable TADF materials. Currently, most solution-processable small molecule TADF materials are modified based on vapor-deposited TADF molecules to endow the TADF materials with good solution-processability. For example, by introducing flexible groups such as methyl, tert-butyl, fluorine atom, trifluoromethyl, sec-butoxy, or adamantane into the rigid TADF materials, the solubility and film-forming ability of the small molecule TADF materials can be improved. However, the introduction of flexible groups will increase the non-radiative loss of the molecules and sacrifice the luminescence efficiency of the TADF materials themselves. Compared with numerous vapor-deposited TADF molecules, the solution-processable high-efficiency small molecule TADF materials are still relatively few and have a low luminescence efficiency.

[0005] Therefore, the development of solution-processable small molecule TADF materials with high luminescence efficiency is a research hotspot in the display field. Summary of the Invention

[0006] Aiming at the defects of the prior art, the present invention provides a boron nitride compound and an organic electroluminescent device, which solve the problems of few solution-processable small molecule TADF materials and the need to improve the luminescence efficiency in the prior art. [[ID=X]]

[0007] To achieve the above object, the present invention provides a boron nitride compound having the structure shown in formula (1) or (2),

[0008]

[0009] wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 are each independently a hydrogen atom, a cyano group, a halogen, a C1-C20 alkoxy group, a C1-C20 alkylthio group, a C1-C20 alkylamino group, a C6-C50 aryloxy group, a C6-C50 arylthio group, a C6-C50 aryl group, a C6-C50 heteroaromatic group, or a C6-C50 aromatic amine group each time they appear.

[0010] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R17 Each occurrence is independently a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, a hexyloxy group, a 2-methylpentyloxy group, a methylthio group, an ethylthio group, a propylthio group, a n-butylthio group, a sec-butylthio group, a tert-butylthio group, a methylamino group, an ethylamino group, a propylamino group, a butylamino group, a pentylamino group, an isopentylamino group, a neopentylamino group, a tert-pentylamino group, a hexylamino group, a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, a dipentylamino group, a diisopentylamino group, a dineopentylamino group, a ditert-pentylamino group or a dihexylamino group.

[0011] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 Each occurrence is independently an o-, m-, p-methylphenylamino group, an o-, m-, p-ethylphenylamino group, an o-, m-, p-propylphenylamino group, an o-, m-, p-isopropylphenylamino group, an o-, m-, p-methoxyphenylamino group, an o-, m-, p-ethoxyphenylamino group, an o-, m-, p-propoxyphenylamino group, an o-, m-, p-fluorophenylamino group, an o-, m-, p-chlorophenylamino group, an o-, m-, p-bromophenylamino group, an o-, m-, p-iodophenylamino group, a bis(o-, m-, p-methylphenyl)amino group, a bis(o-, m-, p-ethylphenyl)amino group, a bis(o-, m-, p-propylphenyl)amino group, a bis(o-, m-, p-isopropylphenyl)amino group, a bis(o-, m-, p-methoxyphenyl)amino group, a bis(o-, m-, p-ethoxyphenyl)amino group, a bis(o-, m-, p-propoxyphenyl)amino group, a bis(o-, m-, p-fluorophenyl)amino group, a bis(o-, m-, p-chlorophenyl)amino group, a bis(o-, m-, p-bromophenyl)amino group, a bis(o-, m-, p-iodophenyl)amino group or a triphenylamino group.

[0012] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 Each occurrence is independently a phenoxy group, a phenylthio group, a phenyl group, a diphenyl group, a triphenyl group, a tetraphenyl group, a pyrenyl group, a fluorene, a spirofluorene, a pyridine, a pyrazine, a pyrimidine, a triazine or a tetrazine.

[0013] Preferably, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 are all hydrogen atoms, and R 17 is selected from C6-C50 aromatic amine groups.

[0014] Preferably, the C6-C50 aromatic amine group is selected from any one of the following groups:

[0015]

[0016]

[0017]

[0018]

[0019]

[0020] The present invention also provides a mixture, which comprises the boron nitride compound and at least one organic functional material, and the organic functional material is selected from a hole injection material, a hole transport material, an electron transport material, an electron injection material, an electron blocking material, a hole blocking material, a light-emitting guest material, a light-emitting host material or an organic dye.

[0021] The present invention also provides an application of the boron nitride compound or the mixture in an organic electroluminescent device prepared by a solution processing method.

[0022] The present invention also provides a composition, which comprises the boron nitride compound or the mixture, and at least one organic solvent.

[0023] The present invention also provides an organic electroluminescent device, which comprises at least one functional layer, and the functional layer comprises the boron nitride compound or the mixture, or the functional layer is prepared from the composition.

[0024] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, at least the following beneficial effects can be achieved:

[0025] (1) The boron nitride compound provided by the present invention has a single structure, a determined molecular weight, and is easy to purify, and has the advantages of a simple synthesis method, short steps, a short synthesis cycle, and good reproducibility in multiple syntheses. The ΔE of the boron nitride compound provided by the present invention STSmall, high PLQY, with good solubility, excellent film-forming property and stable film morphology, can be used as a solution-processable thermally activated delayed fluorescence material, suitable for preparing large-area OLED devices by solution method.

[0026] (2) The boron-nitrogen compound provided by the present invention has the property of thermally activated delayed fluorescence. This acceptor has strong electron-withdrawing ability, large rigidity and large steric hindrance effect, effectively improving the luminescence performance of the material; the large spatial structure and steric hindrance can effectively inhibit the intermolecular interaction, reduce the aggregation between molecules, and effectively improve the solubility and film-forming performance of the material; the strong electron-withdrawing ability of this acceptor unit can reduce the overlap of the molecular frontier orbitals, thereby reducing the lowest excited singlet-triplet energy level difference, enabling the triplet excitons to return to the singlet state through reverse intersystem crossing, and finally returning to the ground state by radiative transition to emit fluorescence, improving the exciton utilization rate, and ultimately achieving the purpose of improving the device efficiency.

[0027] (3) The present invention applies the above boron-nitrogen compound to an organic electroluminescent device through a solution processing process, which has the advantages of simple preparation method and low cost. Moreover, the maximum external quantum efficiency of the organic electroluminescent device is as high as 26.04%, and the color coordinates are (X = 0.18, Y = 0.36), having good optoelectronic properties.

[0028] (4) The boron-nitrogen compound provided by the present invention can further improve its carrier transport characteristics and fluorescence quantum yield by changing the modifying groups on the aromatic structure; it can also effectively regulate the conjugation length, electrophilicity, film-forming property and horizontal dipole orientation of the molecule by changing the connected chemical structure, so that it has good comprehensive performance when used as a small molecule TADF material in solution-processed organic electroluminescent devices. Description of the Drawings

[0029] Figure 1 is the electroluminescence spectrum diagram of the organic electroluminescent device prepared in Example 7;

[0030] Figure 2 is the performance diagram of the organic electroluminescent device prepared in Example 7, where content (a) is the relationship diagram of current efficiency-external quantum efficiency, content (b) is the relationship diagram of voltage-current density, content (c) is the voltage-luminance diagram, and content (d) is the atomic force micrograph of the film prepared by spin-coating the luminescent material P1. Detailed Embodiments

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Unless otherwise specified, all technical and scientific terms used herein have the ordinary meanings ascribed to them in the art to which the claimed subject matter pertains. In the event that there are multiple definitions for a term, the definition herein shall prevail.

[0033] Unless otherwise indicated, when disclosing or claiming any type of range (such as wavelength, full width at half maximum, and number of substituents), it is intended to separately disclose or claim each possible value that the range could reasonably cover, including any sub-ranges subsumed therein. For example, in this document, a numerical range defined for the number of carbon atoms in an alkoxy group such as 1 to 20 etc. indicates integers within that range.

[0034] The terms "group" and "chemical group" refer to specific fragments or functional groups in a molecule.

[0035] Unless otherwise specified, this application employs standard nomenclature and standard laboratory procedures and techniques in analytical chemistry, organic synthetic chemistry, and optics. In certain cases, standard techniques are used for chemical synthesis, chemical analysis, and detection of the performance of light-emitting devices. Unless otherwise indicated, this application uses conventional methods such as mass spectrometry and elemental analysis, and the procedures and conditions for each step can refer to the conventional operating procedures and conditions in the art.

[0036] The reagents and raw materials used in this application are commercially available or can be prepared by conventional chemical synthesis methods. [[ID=I4]]

[0037] In this application, unless otherwise specified, the number of said "substitutions" can be one or more; when there are multiple substitutions, it can be 2, 3, or 4. And, when the number of said "substitutions" is multiple, the "substitutions" can be the same or different. The position of the "substitution", unless otherwise specifically stated, can be arbitrary.

[0038] The terms "ortho", "meta", and "para" refer to the situation where there are exactly two hydrogen atoms on a benzene ring replaced by other groups. If it is at the 1, 2 positions, it is the ortho position, at the 1, 3 positions, it is the meta position, and at the 1, 4 positions, it is the para position.

[0039] The term "halogen" refers to fluorine, chlorine, bromine, or iodine. ]>

[0040] The term "alkoxy" refers to a group having the structure "-O-alkyl", that is, an alkyl group is connected to other groups via an oxygen atom. In some embodiments, the above C1-C20 alkoxy groups are selected from methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, neopentyloxy, tert-pentyloxy, hexyloxy, or 2-methylpentyloxy.

[0041] ]>The term "alkylthio" refers to a group having the structure "-S-alkyl", that is, an alkyl group is connected to other groups via an S atom. In some embodiments, the above C1-C20 alkylthio groups are preferably methylthio, ethylthio, propylthio, n-butylthio, sec-butylthio, tert-butylthio.

[0042] The term "alkylamino" refers to a group with the structure "-N-alkyl", that is, an alkyl group is connected to other groups via an N atom. In some embodiments, the above alkylamino is preferably a C1-C20 alkylamino, such as methylamino, ethylamino, propylamino, butylamino, pentylamino, isopentylamino, neopentylamino, tert-pentylamino, hexylamino, dimethylamino, diethylamino, dipropylamino, dibutylamino, dipentylamino, diisopentylamino, dineopentylamino, ditert-pentylamino, dihexylamino.

[0043] The term "C n ~C m aryloxy" refers to a group with the structure containing at least one benzene ring and an O-connected group, that is, the benzene ring is connected to other groups via an O atom. In some embodiments, the above aryloxy is phenoxy.

[0044] The term "C n ~C m arylthio" refers to a group with the structure containing at least one benzene ring and an S-connected group, that is, the benzene ring is connected to other groups via an S atom. In some embodiments, the above arylthio is phenylthio.

[0045] The term "C n ~C m aryl" refers to a monocyclic or polycyclic aromatic group having n to m ring carbon atoms (the ring atoms are only carbon atoms), which has at least one carbon ring with a conjugated π-electron system. In some embodiments, the C6-C50 aryl is selected from phenyl, diphenyl, triphenyl, tetraphenyl, pyrenyl, fluorene or spirofluorene.

[0046] The term "C n ~C m heteroaryl group" refers to an aromatic group whose ring atoms contain one or more (such as 1, 2, 3 and 4) heteroatoms selected from nitrogen, oxygen and sulfur, and the ring atoms are n to m, and the heteroaryl is a monocyclic, bicyclic, tricyclic or tetracyclic system, wherein at least one ring is an aromatic ring. In some embodiments, the C6-C50 heteroaryl group is selected from pyridine, pyrazine, pyrimidine, triazine, tetrazine.

[0047] The term "C n ~C m aromatic amine group" refers to a group with the structure containing at least one benzene ring and an amino group, that is, the benzene ring is connected to other groups via an N atom.

[0048] The present invention provides a boron nitride compound having the structure shown in formula (1) or (2),

[0049]

[0050] Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 is independently, each time it appears, a hydrogen atom, a cyano group, a halogen, a C1-C20 alkoxy group, a C1-C20 alkylthio group, a C1-C20 alkylamino group, a C6-C50 aryloxy group, a C6-C50 arylthio group, a C6-C50 aryl group, a C6-C50 heteroaryl group or a C6-C50 aromatic amine group.

[0051] In some embodiments, the above R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 is independently, each time it appears, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, a hexyloxy group, a 2-methylpentyloxy group, a methylthio group, an ethylthio group, a propylthio group, a n-butylthio group, a sec-butylthio group, a tert-butylthio group, a methylamino group, an ethylamino group, a propylamino group, a butylamino group, a pentylamino group, an isopentylamino group, a neopentylamino group, a tert-pentylamino group, a hexylamino group, a dimethylamino group, a diethylamino group, a dipropylamino group, a dibutylamino group, a dipentylamino group, a diisopentylamino group, a dineopentylamino group, a ditert-pentylamino group, a dihexylamino group.

[0052] In some embodiments, the above R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17Each occurrence is independently o-, m-, p-methylphenylamino, o-, m-, p-ethylphenylamino, o-, m-, p-propylphenylamino, o-, m-, p-isopropylphenylamino, o-, m-, p-methoxyphenylamino, o-, m-, p-ethoxyphenylamino, o-, m-, p-propyloxyphenylamino, o-, m-, p-fluorophenylamino, o-, m-, p-chlorophenylamino, o-, m-, p-bromophenylamino, o-, m-, p-iodophenylamino, di(o-, m-, p-methylphenylamino) )amino group, di(o-,m-,p-ethylphenyl)amino group, di(o-,m-,p-propylphenyl)amino group, di(o-,m-,p-isopropylphenyl)amino group, di(o-,m-,p-methoxyphenyl)amino group, di(o-,m-,p-ethoxyphenyl)amino group, di(o-,m-,p-propyloxyphenyl)amino group, di(o-,m-,p-fluorophenyl)amino group, di(o-,m-,p-chlorophenyl)amino group, di(o-,m-,p-bromophenyl)amino group, di(o-,m-,p-iodophenyl)amino group or triphenylamino group.

[0053] In some embodiments, the above R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 、R 17 Each occurrence is independently phenoxy, phenylthio, phenyl, diphenyl, triphenyl, naphthacene, pyrenyl, fluorene, spirofluorene, pyridine, pyrazine, pyrimidine, triazine, or tetrazine.

[0054] In some embodiments, the above R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 、R 11 、R 12 、R 13 、R 14 、R 15 、R 16 are all hydrogen atoms, R 17 Selected from C6~C50 aromatic amine groups.

[0055] In some embodiments, the C6-C50 aromatic amine group is selected from any one of the following groups:

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] In some embodiments, the boron nitride compound provided by the present application can be used as an organic light-emitting material in the functional layer of an organic electroluminescent device, especially in the functional layer of an OLED device. The organic functional material can be, but is not limited to, a hole injection material (HIM), a hole transport material (HTM), an electron transport material (ETM), an electron injection material (EIM), an electron blocking material (EBM), a hole blocking material (HBM), a luminescent guest material (Gust Emitter), a luminescent host material (HostEmitter), and an organic dye.

[0062] The present application also provides a mixture, which includes the above-mentioned boron nitride compound and at least one other organic functional material. It can be understood that the other organic functional material can be a small molecule organic material and a polymer material.

[0063] In some embodiments, the above-mentioned boron nitride compound or the above-mentioned mixture is used to prepare an organic electroluminescent device by a solution processing method. Among them, the above-mentioned solution processing method can be, but is not limited to, spin coating, inkjet printing, roll-to-roll, gravure printing, screen printing, etc.

[0064] The present application also relates to a composition, including at least one of the above-mentioned boron nitride compounds or mixtures, and at least one organic solvent. In some embodiments, the above-mentioned organic solvent is selected from at least one of aromatic or heteroaromatic-based solvents, ester-based solvents, aromatic ketone-based solvents, aromatic ether-based solvents, aliphatic ketones, aliphatic ethers, alicyclic compounds, olefinic compounds, borate compounds, and phosphate compounds.

[0065] In some embodiments, the above-mentioned composition is a solution. In still other embodiments, the above-mentioned composition is a suspension. The above-mentioned solution or the above-mentioned suspension can additionally include additives, wherein the above-mentioned additives are used to adjust viscosity, adjust film-forming properties, improve adhesion, etc. In some embodiments, the above-mentioned additives can be, but are not limited to, at least one of surface active compounds, lubricants, wetting agents, dispersants, water repellents, and adhesives. It can be understood that the above-mentioned organic solvent can be used alone or as a mixed solvent of two or more organic solvents. The above-mentioned organic solvent can evaporate from the solvent system to form a thin film including organic compounds.

[0066] The present application also relates to the application of the above-mentioned boron nitride compound, the above-mentioned mixture, or the above-mentioned composition in an organic electroluminescent device.

[0067] The present application also provides an organic electroluminescent device, which includes at least one functional layer, and the above-mentioned functional layer includes the above-mentioned boron nitride compound or the above-mentioned mixture, or the above-mentioned functional layer is prepared from the above-mentioned composition. In some embodiments, the above-mentioned organic functional layer can be selected but not limited to a hole injection layer, a hole transport layer, a light-emitting layer, an electron blocking layer, an electron injection layer, an electron transport layer, or a hole blocking layer. Preferably, the functional layer is a light-emitting layer, that is, the light-emitting layer contains at least one of the above-mentioned boron nitride compounds or the above-mentioned mixture, or the light-emitting layer is prepared from the above-mentioned composition.

[0068] In some embodiments, the above-mentioned light-emitting material is applied as a light-emitting layer in an organic electroluminescent device processed by a solution method. In some embodiments of the present invention, the above-mentioned light-emitting material is applied as a guest in an organic electroluminescent device processed by a solution method. In a specific embodiment of the present invention, the light-emitting material is dissolved in an organic solvent, spin-coated at a certain rotation speed, and then annealed to finally prepare a uniform and smooth thin film, wherein the concentration of the light-emitting material is 5 mg / mL to 30 mg / mL, the doping concentration of the light-emitting material is 1 wt% to 10 wt%, the rotation speed of spin-coating is 500 r / min to 3000 r / min, the annealing temperature is 50 °C to 150 °C, and the annealing time is 10 min to 60 min.

[0069] In some embodiments, the above-mentioned organic electroluminescent device can be, but not limited to, an organic light-emitting diode (OLED), an organic photovoltaic cell (OPV), an organic light-emitting electrochemical cell (OLEEC), an organic field-effect transistor (OFET), an organic laser, an organic spintronic device, an organic sensor, and an organic plasmon emitting diode, etc. Particularly preferred are organic electroluminescent devices such as OLED, OLEEC, and organic light-emitting field-effect transistors. In a preferred embodiment, the above-mentioned organic electroluminescent device is an OLED.

[0070] In some embodiments, the organic electroluminescent device of the present application is a solution-type organic electroluminescent device, and one or more functional layers of the above-mentioned solution-type organic electroluminescent device are prepared by a spin-coating method. In a specific embodiment of the present invention, the above-mentioned solution-type organic electroluminescent device is a solution-type OLED.

[0071] The present application also relates to the application of the above-mentioned organic electroluminescent device in various electronic devices. Among them, the above-mentioned electronic devices can be, but not limited to, display devices, lighting devices, light sources, sensors, etc.

[0072] The following specifically illustrates the present application through specific examples. The following examples are only partial examples of the present application and do not limit the present application. The present application is not limited to the following examples.

[0073] Example 1 Synthesis of Small-Molecule Luminescent Material P1

[0074]

[0075] (1) 2-Bromopyrimidine (0.477 g, 3.00 mmol) and (4-bromophenyl)-boronic acid (0.60 g, 3.00 mmol) were added to a two-necked flask, 20 mL of toluene solution was added, and the mixture was stirred until completely dissolved. Then, 10 mL of an aqueous solution of Na2CO3 (0.32 g, 9.00 mmol) and 10 mL of absolute ethanol were added. After bubbling with Ar for 30 min, Pd(PPh3)4 (0.14 g, 0.12 mmol) was quickly added. Finally, under Ar protection, the mixture was heated at 70 °C for 12 h. After cooling to room temperature, it was extracted with dichloromethane and washed three times with water. The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 7:1, V / V) to obtain 0.41 g of white solid 1 with a yield of 58%. 1 H NMR (400 MHz, CDCl3) δ 8.71 (d, J = 4.8 Hz, 2H), 8.25 (d, J = 8.5 Hz, 2H), 7.54 (d, J = 8.5 Hz, 2H), 7.12 (dd, J = 5.8, 3.8 Hz, 1H).

[0076]

[0077] (2) The above white solid 1 (2.07 g, 8.81 mmol), i-Pr2EtN (1.25 g, 9.69 mmol) and 60 mL of absolute dichloromethane were added to a single-necked flask, and the flask was purged with Ar three times. Then, at 0 °C, a 1 M solution of BBr3 in dichloromethane (26.43 mL, 26.43 mmol) was slowly added dropwise to the reaction mixture. The mixture was stirred at room temperature for 24 h. Then, the reaction mixture was concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2:1, V / V) to obtain 1.07 g of white solid 2 with a yield of 30%. 1 H NMR (400 MHz, CDCl3) δ 9.07 (d, J = 4.8 Hz, 1H), 9.03 (d, J = 5.9 Hz, 1H), 7.94 (s, 1H), 7.88 (d, J = 8.1 Hz, 1H), 7.59–7.49 (m, 2H). 13 C NMR (101 MHz, CDCl3) δ 164.34 (s), 163.00 (s), 151.37 (s), 133.78 (s), 132.57 (s), 131.08 (d, J = 18.3 Hz), 125.76 (s), 119.38 (s).

[0078]

[0079] (3) Dissolve the above-mentioned white solid 2 (0.10 g, 0.25 mmol) and triphenyltin salt (0.23 g, 0.63 mmol) in 5 mL of anhydrous dichloromethane, displace with Ar three times, and then quickly add anhydrous AlCl3 (0.13 mg, 0.10 mmol). After stirring for 24 h under Ar protection, quench with water, extract with 10 mL of dichloromethane, wash with 3 × 10 mL of water, dry over anhydrous sodium sulfate, filter, concentrate the reaction mixture under reduced pressure, and purify the product by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2:1, V / V) to obtain 0.093 g of white solid 3 with a yield of 93%. 1 1H NMR (400 MHz, CDCl3) δ 8.99 (dd, J = 4.6, 1.5 Hz, 1H), 8.61 (dd, J = 5.7, 1.4 Hz, 1H), 7.99 (d, J = 8.2 Hz, 1H), 7.79 (s, 1H), 7.46 (d, J = 8.2 Hz, 1H), 7.30 (t, J = 5.2 Hz, 1H), 7.17–7.07 (m, 10H). 13 13C NMR (101 MHz, CDCl3) δ 164.74, 160.65 150.30, 132.65, 131.93, 129.03, 128.36, 126.70, 125.29, 124.60, 116.75.

[0080]

[0081] (4) Add the above-mentioned white solid 3 (0.55 g, 1.39 mmol), 10H-spiro[acridine-9,9'-fluorene] (SPAc) (0.49 g, 1.45 mmol), Pd(OAc)2 (0.031 g, 0.14 mmol), P(t-Bu)3HBF4 (0.040 g, 0.14 mmol), K2CO3 (0.58 g, 4.16 mmol) and 40 mL of anhydrous toluene solution into a two-necked flask, displace with Ar three times, and reflux for 48 h under Ar protection. After cooling to room temperature, then concentrate the filtrate under reduced pressure. Purify by silica gel column chromatography, eluent: petroleum ether / dichloromethane = 1:1, V / V), to obtain 0.66 g of pale yellow solid P1 with a yield of 70%. 11H NMR (400 MHz, CDCl3) δ 9.14 (dd, J = 4.6, 2.0 Hz, 1H), 8.80 (dd, J = 5.7, 2.0 Hz, 1H), 8.55 (d, J = 8.0 Hz, 1H), 7.92 (s, 1H), 7.79 (d, J = 7.5 Hz, 2H), 7.53 (dd, J = 8.1, 1.6 Hz, 1H), 7.43 (t, J = 7.1 Hz, 3H), 7.36 (t, J = 7.4 Hz, 2H), 7.31–7.15 (m, 12H), 6.89 (t, J = 7.7 Hz, 2H), 6.55 (t, J = 7.2 Hz, 2H), 6.46 (d, J = 8.3 Hz, 2H), 6.39 (d, J = 7.8 Hz, 2H). 13 13C NMR (101 MHz, CDCl3) δ 165.78, 161.72, 156.72, 151.56, 145.45, 141.08, 139.21, 134.90, 133.64, 129.47, 128.45, 127.80, 127.55, 127.23, 126.92, 126.27, 125.95, 124.77, 120.61, 119.84, 117.78, 114.83, 56.83. HMS (ESI): m / z calcd for C 47 H 32 BN3 [M] + 649.27, found 650.2772。

[0082]

[0083] Example 2 Synthesis of Small Molecule Luminescent Material P2

[0084]

[0085] Same as Example 1, using acridine (DMAc) instead of 10-Hydro-spiro[acridine-9,9'-fluorene], the luminescent material P2 was obtained with a yield of 86%.

[0086] Example 3 Synthesis of Small Molecule Luminescent Material P3

[0087]

[0088] Same as Example 1, using phenoxazine (PXZ) instead of 10-Hydro-spiro[acridine-9,9'-fluorene], the luminescent material P3 was obtained with a yield of approximately 81%.

[0089] Example 4 Synthesis of Small Molecule Luminescent Material P4

[0090]

[0091] Similar to Example 1, phenothiazine (PTZ) was used to replace 10 - hydro - spiro[acridine - 9,9'-fluorene] to obtain the luminescent material P4, and the yield was about 79%.

[0092] Example 5 Synthesis of small - molecule luminescent material P5

[0093]

[0094] Similar to Example 1, carbazole (Cz) was used to replace 10 - hydro - spiro[acridine - 9,9'-fluorene] to obtain the luminescent material P5, and the yield was about 75%.

[0095] Example 6 Synthesis of small - molecule luminescent material P6

[0096]

[0097] Similar to Example 1, diphenylamine (DA) was used to replace 10 - hydro - spiro[acridine - 9,9'-fluorene] to obtain the luminescent material P6, and the yield was about 88%.

[0098] The singlet - triplet energy level differences of the luminescent materials P1 - P6 were tested, and the results are shown in Table 1.

[0099] Table 1 Singlet - triplet energy level differences (ΔE ST ) of the luminescent materials P1 - P6

[0100] Luminescent material <![CDATA[ΔE ST > P1 0.02 P2 0.10 P3 0.01 P4 0.01 P5 0.30 P6 0.16

[0101] The ΔE of the luminescent materials P1 - P6 ST are all small, indicating that the luminescent materials P1 - P6 all have good reverse intersystem crossing performance. The PLQY of the luminescent materials P1 - P6 is greater than 70%, and among them, P1 is close to 100%.

[0102] The luminescent materials P1 - P6 have good solubility and are well - soluble in common organic solvents such as chlorobenzene, dichloromethane, chloroform, toluene, and tetrahydrofuran.

[0103] The luminescent materials P1 - P6 have good thermal stability, and their thermal decomposition temperatures are all above 400 °C, which is beneficial to maintaining the stability of the compounds when preparing optoelectronic devices.

[0104] Example 7

[0105] The organic electroluminescent device was prepared from the luminescent material P1 in Example 1 by solution - processing method:

[0106] The ITO transparent conductive glass is ultrasonically treated in a cleaning agent, washed in deionized water, ultrasonically degreased in a mixed solvent of acetone and ethanol, baked in a clean environment until all moisture is removed, cleaned with ultraviolet light and ozone for 10 min, and bombarded with low-energy cations.

[0107] A hole transport layer of PEDOT:PSS (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate) is spin-coated on the above ITO glass.

[0108] The luminescent material P1 is dissolved in a chlorobenzene solvent at a concentration of 10 mg / mL. On top of the hole transport layer, a luminescent layer with P1 as the guest, CzAcSF as the TADF sensitizer, and mCP as the host is further spin-coated (at a rotation speed of 900 r / min). The doping concentration of P1 is 1 wt% - 10 wt%, and then it is annealed at 60 °C for 30 min.

[0109] A layer of DPEPO is further evaporated as an exciton blocking layer; a layer of TmPyPB is evaporated as an electron transport layer; finally, a LiF layer and Al are sequentially evaporated on top of the above electron transport layer as the cathode layer of the device.

[0110] Device structure: ITO / PEDOT:PSS(40 nm) / CzAcSF:P1:mCP(30 nm) / DPEPO(9 nm) / TmPyPB(40 nm) / LiF(1.2 nm) / Al(120 nm).

[0111] The structural formulas of PEDOT:PSS, mCP, DPEPO, TmPyPB, and CzAcSF are as follows:

[0112]

[0113] The characteristics of the device such as current, voltage, brightness, and emission spectrum are tested using a PHOTORESEARCH Spectra Scan PR735 photometer and a KEITHLEY 2400 Source Meter constant current source. The performance test of the device is carried out at room temperature and in an ambient atmosphere. The external quantum efficiency (EQE) of the device is calculated using the Lambert distribution.

[0114] Specifically, the electroluminescence spectrum of the organic electroluminescent device with a P1 doping concentration of 1% is as Figure 1 shown, and the relationships between current density - external quantum efficiency, voltage - current density, and voltage - brightness of the organic electroluminescent device are as shown in Figure 2 Content (a), Figure 2 Content (b), Figure 2 Content (c) respectively.

[0115] The formability of the film prepared by spin-coating the luminescent material P1 was evaluated using an atomic force microscope (AFM). As Figure 2 shown in content (d), the film prepared by spin-coating the luminescent material P1 is smooth and uniform, with a root mean square (RMS) roughness of 1.73 nm, and has excellent film-forming properties.

[0116] The device performance indicators are as follows:

[0117] Color coordinates: (X = 0.18, Y = 0.36);

[0118] Turn-on voltage: 3.6 V;

[0119] Current efficiency: 59.92 cd / A

[0120] External quantum efficiency: 26.04%.

[0121] In summary, it can be seen that the small molecule luminescent material provided by the present invention has good solubility, high singlet and triplet energy levels, and excellent film-forming properties. The OLED prepared using the above small molecule luminescent material as the light-emitting layer exhibits excellent optoelectronic properties, has a low turn-on voltage and a high current efficiency. Among them, the turn-on voltage is 3.6 V, the maximum current efficiency is 59.92 cd / A, and the external quantum efficiency can reach 26.04%. Its performance can be comparable to that of traditional vacuum evaporation OLED devices.

[0122] It is easy for those skilled in the art to understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A boron nitride compound, characterized in that, It has the structure shown in formula (1). Among them, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 is independently, each time it appears, a hydrogen atom, a cyano group, a halogen, a C1-C20 alkoxy group, a C1-C20 alkylthio group, a C1-C20 alkylamino group, a C6-C50 aryloxy group, a C6-C50 arylthio group, a C6-C50 aryl group, a C6-C50 heteroaryl group or a C6-C50 aromatic amine group.

2. The boron nitride compound according to claim 1, characterized in that, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 Each occurrence is independently methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, neopentyloxy, tert-pentyloxy, hexyloxy, 2-methylpentyloxy, methylthio, ethylthio, propylthio, n-butylthio, sec-butylthio, tert-butylthio, methylamino, ethylamino, propylamino, butylamino, pentylamino, isopentylamino, neopentylamino, tert-pentylamino, hexylamino, dimethylamino, diethylamino, dipropylamino, dibutylamino, dipentylamino, diisopentylamino, dineopentylamino, ditert-pentylamino or dihexylamino.

3. The boron nitride compound according to claim 1, wherein, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 Each occurrence is independently o-, m-, p-methylphenylamino, o-, m-, p-ethylphenylamino, o-, m-, p-propylphenylamino, o-, m-, p-isopropylphenylamino, o-, m-, p-methoxyphenylamino, o-, m-, p-ethoxyphenylamino, o-, m-, p-propoxyphenylamino, o-, m-, p-fluorophenylamino, o-, m-, p-chlorophenylamino, o-, m-, p-bromophenylamino, o-, m-, p-iodophenylamino, bis(o-, m-, p-methylphenyl)amino, bis(o-, m-, p-ethylphenyl)amino, bis(o-, m-, p-propylphenyl)amino, bis(o-, m-, p-isopropylphenyl)amino, bis(o-, m-, p-methoxyphenyl)amino, bis(o-, m-, p-ethoxyphenyl)amino, bis(o-, m-, p-propoxyphenyl)amino, bis(o-, m-, p-fluorophenyl)amino, bis(o-, m-, p-chlorophenyl)amino, bis(o-, m-, p-bromophenyl)amino, bis(o-, m-, p-iodophenyl)amino or triphenylamino.

4. The boron nitride compound according to claim 1, characterized in that, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 Each occurrence is independently phenoxy, phenylthio, phenyl, diphenyl, triphenyl, tetraphenyl, pyrenyl, fluorene, spirofluorene, pyridine, pyrazine, pyrimidine, s-triazine or tetrazine.

5. The boron nitride compound according to claim 1, characterized in that, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 , R 11 , R 12 , R 13 , R 14 , R 15 , R 16 are hydrogen atoms, and R 17 is selected from C6 - C50 aromatic amine groups.

6. The boron nitride compound according to claim 5, characterized in that, The C6-C50 aromatic amine group is selected from any one of the following groups: 。 7. A mixture, characterized in that, The mixture includes the boron nitride compound according to any one of claims 1 to 6 and at least one organic functional material, and the organic functional material is selected from a hole injection material, a hole transport material, an electron transport material, an electron injection material, an electron blocking material, a hole blocking material, a light-emitting guest material, a light-emitting host material or an organic dye.

8. Use of the boron nitride compound according to any one of claims 1 to 6 or the mixture according to claim 7, characterized in that It is applied to an organic electroluminescent device prepared by a solution processing method.

9. A composition, characterized in that, The composition includes the boron nitride compound according to any one of claims 1 to 6 or the mixture according to claim 7, and at least one organic solvent.

10. An organic electroluminescent device, characterized in that, It includes at least one functional layer, and the functional layer includes the boron nitride compound according to any one of claims 1 to 6 or the mixture according to claim 7, or the functional layer is prepared from the composition according to claim 9.

Images