Dark blue light narrow-band luminescent material, preparation method thereof and electronic device

Abstract

The invention relates to the technical field of luminescent materials, in particular to a deep blue light narrow-band luminescent material, a preparation method thereof and an electronic device. The molecular structure general formula of the deep blue light narrow-band luminescent material provided by the invention is shown in the specification, and according to the deep blue light narrow-band luminescent material provided by the invention, an oxygen group atom is integrated into a resonance unit, and the oxygen group atom is further thickened with an O-B-N unit to form a more rigid molecular structure; on one hand, the spin-orbit coupling degree of the material can be promoted, so that a rapid exciton conversion process is realized, and on the other hand, a relatively narrow emission spectrum and dark blue light emission can be realized through a more rigid molecular structure; therefore, the material has the characteristics of high anti-intersystem crossing rate and deep blue light narrow band luminescence, and has good application in electronic devices.

Description

Technical Field

[0001] The present application belongs to the technical field of luminescent materials, and in particular relates to a deep blue narrow-band luminescent material, a preparation method thereof, and an electronic device. Background Art

[0002] Organic light-emitting diodes (OLEDs) have advantages such as flexibility, wide viewing angle, high contrast, high brightness, fast response speed, and simple manufacturing process, making them popular in modern scientific research and the commercial display industry. According to statistical distribution laws, during the electroluminescence (EL) process, the ratio of triplet and singlet states of excitons generated by the recombination of electrons and holes is 3:1. Luminescence achieved by the radiative transition of singlet excitons is called fluorescence, and luminescence achieved by the radiative transition of triplet excitons is called phosphorescence. Therefore, traditional fluorescent electroluminescence can only utilize a maximum of 25% of the input energy, while the remaining energy (75%) in the excited triplet state is not used. Therefore, how to achieve luminescence from excited triplet excitons is crucial to improving the quantum efficiency of the device.

[0003] By introducing heavy atoms, the spin-orbit coupling between different excited states can be effectively promoted, so that the lowest excited triplet state that was originally spin-forbidden can radiatively transition to produce photons. Therefore, 75% of the triplet excitons are fully utilized to achieve phosphorescence, and its internal quantum efficiency can theoretically reach 100%. However, since phosphorescent materials generally require the use of heavy metals such as iridium and platinum, they are not only expensive but also highly toxic. Therefore, thermally activated delayed fluorescence (TADF) materials came into being. This type of material also theoretically has an internal quantum efficiency of 100% and is composed only of organic elements, with low cost. It is regarded as the most promising third-generation OLED material.

[0004] Traditional TADF materials are usually composed of a donor-acceptor structure, which can reduce the singlet-triplet energy level difference of the material and achieve effective TADF luminescence. However, due to the strong charge transfer properties of this type of molecule, during the excitation emission process, the structure has a large relaxation and the emission spectrum has a large red shift, resulting in a wide emission spectrum of the material and it is difficult to achieve deep blue light luminescence properties. Therefore, constructing rigid TADF molecules with multiple resonance effects is of great significance for achieving high-efficiency deep blue narrow-band OLEDs. However, high-performance deep blue light multiple resonance TADF molecules are always difficult to achieve; in addition, deep blue light multiple resonance TADF molecules often have a large singlet-triplet energy level difference, resulting in a small anti-intersystem crossing rate of the material, and ultimately showing a large efficiency roll-off when applied to OLEDs, which is not conducive to its commercial development. Summary of the Invention

[0005] The purpose of this application is to provide a deep blue narrow-band luminescent material and its preparation method and electronic device, aiming to solve the problem of providing a narrow-band deep blue light luminescent material with a faster anti-intersystem crossing rate.

[0006] To achieve the above application objectives, the technical solutions adopted in this application are as follows:

[0007] In a first aspect, the present application provides a deep blue narrow-band luminescent material, the molecular structure of which is shown as follows:

[0008]

[0009] Wherein, X is selected from an oxygen atom, and R1, R2, R3, R4, R5, and R6 are independently selected from at least one of a halogen atom and an alkyl group of 1 to 5 carbon atoms.

[0010] In a second aspect, the present application provides a method for preparing a deep blue narrow-band luminescent material, comprising:

[0011] Reacting compound G with boron tribromide to obtain the deep blue narrow-band luminescent material provided in the first aspect of the present application;

[0012]

[0013] In a third aspect, the present application provides an electronic device, wherein the deep blue narrow-band luminescent material provided in the first aspect of the present application and / or the deep blue narrow-band luminescent material prepared by the preparation method provided in the second aspect of the present application is used in the electronic device.

[0014] The deep-blue narrow-band luminescent material provided in the first aspect of the present application, based on the general formula of the molecular structure, can be seen that the deep-blue narrow-band luminescent material integrates oxygen atoms into the resonance unit, and further condenses it with the OBN unit to form a more rigid molecular structure. On the one hand, it can promote the degree of spin-orbit coupling of this type of material, thereby realizing a rapid exciton transition process. On the other hand, the more rigid molecular structure can achieve a narrower emission spectrum and deep-blue light emission; therefore, the present application forms a deep-blue narrow-band thermally activated delayed fluorescent material that can improve the anti-intersystem crossing rate, which has great application in electronic devices such as electroluminescent devices.

[0015] The second aspect of the present application provides a method for preparing a deep blue narrow-band luminescent material, which is prepared by reacting compound G with boron tribromide. This preparation method is not only simple in process, but also can prepare a deep blue narrow-band thermally activated delayed fluorescent material that can improve the reverse intersystem crossing rate.

[0016] The electronic device provided in the third aspect of the present application uses the deep blue narrow-band luminescent material unique to the present application. Based on the characteristics of the deep blue narrow-band luminescent material that improves the anti-intersystem crossing rate and deep blue narrow-band luminescence, the electronic device of the present application has the advantages of lower efficiency roll-off, high stability and long life. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0018] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0019] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0020] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0021] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0022] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0023] The terms "first" and "second" are used solely for descriptive purposes to distinguish objects, such as substances, from one another and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features being referred to. For example, without departing from the scope of the embodiments of this application, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features.

[0024] The traditional TADF material structure has large relaxation and the emission spectrum has a large red shift, resulting in a wide emission spectrum and difficulty in achieving deep blue light emission. The current deep blue light multi-resonance TADF molecules often have a large singlet-triplet energy level difference, resulting in a low anti-intersystem crossing rate of the material. Ultimately, when applied to OLEDs, it shows a large efficiency roll-off, which is not conducive to its commercial development. Therefore, it is necessary to develop a new narrow-band deep blue light emitting material with a faster anti-intersystem crossing rate, which is of great significance to promoting the application of low-cost TADF materials in OLEDs. Currently, the efficiency roll-off of organic light-emitting diodes is very serious as the brightness increases.

[0025] Based on the above considerations, this application studies and develops a new deep-blue narrow-band luminescent material, in which oxygen atoms are integrated into the resonance unit and further fused with the OBN unit to form a more rigid molecular structure, aiming to solve the problems of slow antisystem crossing rate and wide spectrum in existing deep-blue multi-resonance TADF materials. At the same time, the deep-blue narrow-band luminescent material developed by this application has the characteristics of simple synthesis method, low synthesis cost and can be prepared in large quantities. The electronic devices prepared using this type of material have low efficiency roll-off and high device stability. The specific plan is as follows.

[0026] In a first aspect, the embodiments of the present application provide a deep blue narrow-band luminescent material. The general molecular structure formula of the deep blue narrow-band luminescent material provided in the embodiments of the present application is as follows:

[0027]

[0028] Wherein, X is selected from an oxygen atom, and R1, R2, R3, R4, R5, and R6 are independently selected from at least one of a halogen atom and an alkyl group of 1 to 5 carbon atoms.

[0029] Based on the general formula of the molecular structure, it can be seen that the deep blue narrow-band luminescent material of the embodiment of the present application integrates oxygen atoms into the resonance unit, and further condenses it with the oxygen (O)-boron (B)-nitrogen (N) unit to form a more rigid molecular structure. On the one hand, it can promote the spin-orbit coupling degree of this type of material, thereby realizing a rapid exciton transition process. On the other hand, the more rigid molecular structure can achieve a narrower emission spectrum and deep blue light emission; therefore, the above-mentioned deep blue narrow-band luminescent material provided in the embodiment of the present application is a deep blue narrow-band thermally activated delayed fluorescence material that can improve the anti-intersystem crossing rate, and has great application in electronic devices such as electroluminescent devices.

[0030] Specifically, the structural design of the deep-blue narrow-band luminescent material of the present application adopts the strategy of integrating multiple resonance units with dense oxygen atoms. By integrating heavy oxygen atoms into the multiple resonance units to form a rigid multiple resonance thermally activated delayed fluorescence material, deep blue light luminescence, extremely narrow emission spectrum and extremely high antisystem crossing rate are achieved.

[0031] In some embodiments, the deep blue narrow-band luminescent material of the present invention has a luminescence peak position ranging from about 435 to 455 nm, a half-peak width less than 20 nm, and an anti-intersystem crossing rate greater than 10 5 s -1 In addition, the deep-blue narrow-band luminescent material has good thermal stability, with a thermal decomposition temperature of over 400°C. It also has good solubility in commonly used organic solvents (such as dichloromethane, chloroform, and tetrahydrofuran), and can be used in high-performance solution-processed and vacuum-deposited electronic devices.

[0032] In some embodiments, the oxygen group atom of X includes at least one of oxygen (O), sulfur (S), selenium (Se), and tellurium (Te). These oxygen group atoms have similar properties, and integrating them into the resonance unit and fusing them with the OBN unit can form a more rigid molecular structure. For example, in some embodiments, X can be selected as oxygen.

[0033] In some embodiments, R1, R2, R3, R4, R5, and R6 may be the same or different, and specifically, are independently selected from at least one of a halogen atom and an alkyl group of 1 to 5 carbon atoms. The halogen atom includes at least one of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), and the alkyl group of 1 to 5 carbon atoms may be a methyl group, an ethyl group, a propyl group, a butyl group, or the like.

[0034] In some embodiments, R1, R2, R3, R4, R5, and R6 are identical. For example, R1, R2, R3, R4, R5, and R6 are all methyl groups, or R1, R2, R3, R4, R5, and R6 are all fluorine atoms. When all of the above groups are methyl groups, the corresponding deep-blue narrow-band luminescent material has excellent solubility; when all of the above groups are fluorine atoms, the corresponding deep-blue narrow-band luminescent material has a further blue-shifted emission spectrum to the deep blue region or even close to the ultraviolet region.

[0035] In some embodiments, according to the selection of X, R1, R2, R3, R4, R5, and R6, a variety of symmetrical or asymmetrical deep blue narrow-band luminescent materials can be formed.

[0036] In some embodiments, the deep blue narrow-band luminescent material includes at least one of the following compounds 1 to 8:

[0037]

[0038] A second aspect of the present application provides a method for preparing a deep blue narrow-band luminescent material, comprising:

[0039] Reacting compound G with boron tribromide to obtain the deep blue narrow-band luminescent material provided in the first aspect of the present application;

[0040]

[0041] In this example, compound G is reacted with boron tribromide to produce a deep-blue narrow-band thermally activated delayed fluorescent material that can enhance the rate of reverse intersystem crossing. This method utilizes a mature reaction type, a one-step borylation reaction, and does not require hazardous reagents such as butyl lithium. This method not only simplifies the process and reduces synthesis costs, but also offers high yields and allows for large-scale production.

[0042] X, R1, R2, R3, R4, R5, and R6 in the compound G correspond to the molecular structure formula of the final deep blue narrow-band luminescent material. Specifically, the reaction of the compound G and boron tribromide (BBr3) can be carried out under inert atmosphere.

[0043] In some embodiments, the reaction conditions of compound G and boron tribromide include: first reacting at 80-150°C for 0.5-2 hours, then raising the reaction temperature to 150-200°C for 12-36 hours, thereby obtaining a deep blue narrow-band luminescent material constructed with multiple resonance units integrated with oxygen atoms.

[0044] In some embodiments, when X in compound G is selected from oxygen, compound G is prepared by reacting compound E and compound F; or, when X in compound G is selected from at least one of sulfur, selenium, and tellurium, compound G is prepared by reacting compound K, compound E, and compound F;

[0045]

[0046] Wherein, X in compound K is selected from at least one of sulfur, selenium and tellurium.

[0047] Specifically, compound E is prepared by reacting compound A and compound B to obtain compound C, and then reacting compound C with compound D;

[0048]

[0049] Specifically, compound K is prepared by reacting compound H and compound I to obtain compound J, which is then reacted with compound D to obtain compound K.

[0050]

[0051] Wherein, X in compound H, compound J and compound K is the same and is selected from at least one of sulfur, selenium and tellurium.

[0052] Specifically, in some embodiments, when X is an oxygen atom in the deep blue narrow-band luminescent material, the preparation method includes the following steps:

[0053] S1, reacting compound A and compound B to obtain compound C;

[0054] S2, reacting the compound C and compound D to obtain compound E;

[0055] S3, reacting the compound E and compound F to obtain compound G (X = oxygen atom);

[0056] S4. Reacting the compound G (X=oxygen atom) with boron tribromide to obtain a corresponding deep blue narrow-band luminescent material.

[0057] The synthetic route is as follows:

[0058]

[0059] For example, the above synthetic route can prepare symmetrical deep blue narrow-band luminescent materials corresponding to compound 1 (wherein R1, R2, R3, R4, R5, and R6 are all methyl groups) and compound 5 (wherein R1, R2, R3, R4, R5, and R6 are all fluorine atoms).

[0060] Optionally, step S1 specifically includes:

[0061] Under inert atmosphere, compound A, compound B and a solvent (such as dimethylformamide) are mixed, and then the temperature of the reaction system is raised to 80-200° C. (for example, 150° C.) and reacted for 0.5-12 hours (for example, 1 hour) to obtain the product compound C.

[0062] Optionally, step S2 specifically includes:

[0063] Under inert atmosphere, compound C, compound D, a catalyst (for example, tris(dibenzylideneacetone)dipalladium Pd2(dba)3), a ligand (for example, 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl SPhos), a base (for example, sodium tert-butoxide) and a solvent (for example, toluene) are mixed, and the temperature of the reaction system is raised to 60-110° C. (for example, 110° C.) and the reaction is carried out for 1-12 hours (for example, 12 hours) to obtain the product compound E.

[0064] Optionally, step S3 specifically includes:

[0065] Under inert atmosphere, compound E, compound F, a catalyst (for example, Pd2(dba)3), a ligand (for example, SPhos), a base (for example, sodium tert-butoxide) and a solvent (for example, toluene) are mixed, and the temperature of the reaction system is raised to 60-110°C (for example, 110°C) for 1-12 hours (for example, 12 hours) to obtain the product compound G (X = oxygen atom).

[0066] Optionally, step S4 specifically includes:

[0067] Under inert atmosphere, compound G (X = oxygen atom), a solvent (for example, o-dichlorobenzene) and BBr3 are mixed, the temperature of the reaction system is raised to 80-150°C (for example, 120°C) and the reaction is carried out for 0.5-2 hours (for example, 1 hour), and then the reaction temperature is raised to 150-200°C (for example, 170°C) and the reaction is carried out for 12-36 hours (for example, 15 hours) to obtain the corresponding deep blue narrow-band luminescent material.

[0068] Specifically, in some embodiments, when X in the deep blue narrow-band luminescent material is at least one of sulfur, selenium, and tellurium, the preparation method includes the following steps:

[0069] T1. reacting compound H with compound I to obtain compound J;

[0070] T2. reacting the compound J with the compound D to obtain compound K;

[0071] T3. Reacting compound K, compound E, and compound F to obtain compound G (X is at least one of sulfur, selenium, and tellurium);

[0072] T4. Reacting compound G (X is at least one of sulfur, selenium, and tellurium) with boron tribromide to obtain an asymmetric deep blue narrow-band luminescent material.

[0073] The synthetic route is as follows:

[0074]

[0075] For example, the above synthetic route can prepare asymmetric deep blue narrow-band luminescent materials corresponding to Compound 2, Compound 3, Compound 4, Compound 6, Compound 7, and Compound 8.

[0076] Optionally, step T1 specifically includes:

[0077] Under inert atmosphere, compound H, compound I and a solvent (for example, acetonitrile) are mixed, and then the temperature of the reaction system is lowered to 0°C, tert-butyl nitrite (tBuONO) is added, and the reaction is maintained at 0°C for 10-60 minutes (for example, 30 minutes), and then the temperature of the reaction system is raised to 25-80°C (for example, 25°C) and the reaction is carried out for 6-12 hours (for example, 12 hours) to obtain the product compound J.

[0078] Optionally, step T2 specifically includes:

[0079] Under inert atmosphere, compound J, compound D, a catalyst (for example, Pd2(dba)3), a ligand (for example, SPhos), a base (for example, sodium tert-butoxide) and a solvent (for example, toluene) are mixed, and the temperature of the reaction system is raised to 60-110°C (for example, 110°C) and the reaction is carried out for 1-12 hours (for example, 12 hours) to obtain the product compound K.

[0080] Optionally, step T3 specifically includes:

[0081] Under inert atmosphere, compound E, compound F, compound K, a catalyst (e.g., Pd2(dba)3), a ligand (e.g., SPhos), a base (e.g., sodium tert-butoxide), and a solvent (e.g., toluene) are mixed, and the temperature of the reaction system is raised to 60-110° C. (e.g., 110° C.) for 1-12 hours (e.g., 12 hours) to obtain a product compound G (X is at least one of sulfur, selenium, and tellurium).

[0082] Optionally, step T4 specifically includes:

[0083] Under inert atmosphere, compound G (X is at least one of sulfur, selenium, and tellurium), a solvent (for example, o-dichlorobenzene), and BBr3 are mixed. The temperature of the reaction system is first raised to 80-150°C (for example, 120°C) for 0.5-2 hours (for example, 1 hour), and then the reaction temperature is raised to 150-200°C (for example, 170°C) for 12-36 hours (for example, 12 hours) to obtain an asymmetric deep blue narrow-band luminescent material.

[0084] The third aspect of the embodiments of the present application provides an electronic device. The electronic device provided by the embodiments of the present application uses the deep blue narrow-band luminescent material provided by the first aspect of the present application and / or the deep blue narrow-band luminescent material prepared by the preparation method provided by the second aspect of the present application.

[0085] The electronic device of the embodiment of the present application uses the deep blue narrow-band luminescent material unique to the present application. Based on the characteristics of the deep blue narrow-band luminescent material that has improved the anti-intersystem crossing rate and deep blue narrow-band luminescence, the electronic device of the embodiment of the present application has the advantages of lower efficiency roll-off, high stability and long life.

[0086] Specifically, the electronic device includes at least one of an organic electroluminescent device, an organic field effect transistor, an organic sensor, an organic laser, and an organic photovoltaic cell device.

[0087] Taking organic electroluminescent devices, such as organic light-emitting diodes (OLEDs), as an example, embodiments of the present application utilize a deep-blue narrow-band luminescent material with multiple resonant blue light integrated with heavy oxygen atoms. This allows the device to simultaneously exhibit a very narrow deep-blue emission spectrum and relatively pure blue light, resulting in high device efficiency, low efficiency roll-off, and a long device life. For example, the maximum external quantum efficiency of the OLED can reach over 35%.

[0088] Specifically, in terms of device fabrication, high device performance can be achieved using a classic device structure. For example, it can be widely applied to solution-processed and vacuum-evaporated organic electroluminescent devices. The deep-blue narrow-band luminescent materials according to the embodiments of this application have excellent solubility in common organic solvents and can be used in high-performance solution-processed organic electroluminescent devices, simplifying the device structure and enabling the application of large-area flexible organic electroluminescent devices.

[0089] Optionally, the electronic device is an organic electroluminescent device, which includes a light-emitting layer, and the light-emitting layer includes the above-mentioned deep blue narrow-band light-emitting material of the embodiment of the present application.

[0090] Optionally, the electronic device is an organic electroluminescent device, which includes a light-emitting layer, which includes a host material and a guest material. The guest material is the deep blue narrow-band luminescent material described in this application. The host material can be commercially available 1,3-bis(N-carbazolyl)benzene (mCP) or 3,3′-bis(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP). The guest material accounts for 0.1-50 wt% of the total mass of the host and guest materials, such as 0.5 wt%, 1 wt%, or 10 wt%.

[0091] Optionally, the organic electroluminescent device may have other functional layers in addition to the light-emitting layer, wherein the organic functional material is selected from, for example, hole injection material, hole transport material, exciton blocking material, electron transport material, electron injection material, and organic light-emitting material.

[0092] In some embodiments, an organic electroluminescent device containing the deep-blue narrow-band luminescent material of the embodiments of the present application has a low start-up voltage (<5.0V), a narrow luminescence spectrum, and has a high external quantum efficiency (>27%) and deep-blue light emission (CIEy<0.1).

[0093] The following describes the details in conjunction with specific embodiments.

[0094] Example 1

[0095] A deep blue narrow-band luminescent material, the structural formula of which is as follows:

[0096]

[0097] The preparation method of the above-mentioned deep blue narrow-band luminescent material comprises the following steps:

[0098] (1) Synthesis of Compound C:

[0099]

[0100] Compound A (5 g, 23.87 mmol), Compound B (3.37 g, 35.81 mmol), and cesium carbonate (11.67 g, 35.81 mmol) were weighed into a clean two-necked flask. The mixture was evacuated and then flushed with nitrogen three times. Under nitrogen, 50 mL of N,N-dimethylformamide (DMF) was added and the temperature of the reaction system was raised to 150°C for 3 hours. The reaction solution was quenched with 50 mL of water and extracted with 3 × 40 mL of dichloromethane. The organic phase was collected, dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. The crude product was separated and purified by silica gel chromatography to obtain 5.41 g of compound C, with a yield of 80%.

[0101] 1 H NMR (400MHz, CDCl3) δ7.44 (t, J = 7.9 Hz, 2H), 7.25 (dt, J = 7.3, 2.8 Hz, 2H), 7.07 (dd, J = 6.0, 4.8 Hz, 3H), 6.96 (t, J = 1.9 Hz, 1H).

[0102] (2) Synthesis of Compound E:

[0103]

[0104] Compound C (5 g, 17.63 mmol), compound D (2.98 g, 17.63 mmol), Pd2(dba)3 (0.11 g, 0.12 mmol), SPhos (0.10 g, 0.24 mmol), and sodium tert-butoxide (2.41 g, 25.03 mmol) were weighed into a clean two-necked flask. The mixture was evacuated and nitrogen-purged three times. Toluene (100 mL) was added under nitrogen protection, and the temperature of the reaction system was raised to 110°C for 12 hours. The reaction solution was quenched with 50 mL of water and extracted with 3 × 40 mL of dichloromethane solution. The organic phase was collected, dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. The crude product was separated and purified by silica gel chromatography to obtain 5.11 g of compound E, with a yield of 78%.

[0105] 1 H NMR (400MHz, DMSO-d6) δ = 7.41-7.32 (m, 6H), 7.18-7.08 (m, 7H), 7.05 (d, J = 7.9Hz, 2H), 6.54 (s, 1H), 6.51 (s, 1H), 6.37 (s, 1H).

[0106] (3) Synthesis of Compound G (X = oxygen atom):

[0107]

[0108] Compound E (2.7 g, 7.25 mmol), compound F (1.0 g, 2.9 mmol), Pd2(dba)3 (0.05 g, 0.06 mmol), SPhos (0.05 g, 0.12 mmol), and sodium tert-butoxide (0.84 g, 8.7 mmol) were weighed into a clean two-necked flask. The mixture was evacuated and nitrogen-purged three times. Toluene (20 mL) was added under nitrogen protection, and the temperature of the reaction system was raised to 110°C for 12 hours. The reaction solution was quenched with 50 mL of water and extracted with 3 × 40 mL of dichloromethane solution. The organic phase was collected, dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. The crude product was separated and purified by silica gel chromatography to obtain 2.24 g of the product, compound G, with a yield of 76%.

[0109] 1 H NMR (400MHz, CDCl3) δ=7.26-7.15(m,13H),7.03(d,J=7.8Hz,8H),6.98(d,J=5.7Hz,3H),6.94(d,J=7.3 Hz, 3H), 6.89 (d, J = 7.9Hz, 4H), 6.76 (s, 4H), 6.45-6.39 (m, 5H), 6.19 (s, 4H), 2.24 (s, 6H), 1.85 (s, 12H).

[0110] (4) Synthesis of the deep blue narrow-band luminescent material shown in compound 1:

[0111]

[0112] Compound G (2 g, 1.97 mmol) was weighed into a clean pressure bottle and vacuumed and nitrogen-purged three times. Under nitrogen protection, o-dichlorobenzene (50 mL) and BBr3 (1.48 g, 5.91 mmol) were added. The temperature of the reaction system was raised to 170°C and allowed to react for 12 hours. The reaction solution was quenched with 50 mL of water and extracted with 3 × 40 mL of dichloromethane. The organic phase was collected, dried over anhydrous sodium sulfate, and concentrated to obtain the crude product. The crude product was separated and purified by silica gel chromatography to obtain 0.65 g of compound 1, with a yield of 32%.

[0113] 1H NMR (600MHz, CDCl3) δ = 10.41 (s, 1H), 9.04 (d, J = 7.5Hz, 2H), 7.64 (t, J = 7.6Hz, 2H), 7.51–7.39 (m, 4H), 7.20 (t, J = 7.8Hz, 8H) ,7.09(d,J=7.7Hz,8H),7.02(t,J=7.4Hz,4H),6.66(s,6H),5.76(d,J=1.4Hz,2H),5.73(s,1H),2.22(s,6H),1.64(s,12H).

[0114] Performance test of deep blue narrow-band luminescent materials

[0115] The photophysical and electrochemical data of the deep blue narrow-band luminescent material represented by Compound 1 are shown in Table 1 below.

[0116] Table 1

[0117] <![CDATA[T d (℃)]]> PL(nm) FWHM(nm) <![CDATA[S1(eV)]]> <![CDATA[T1(eV)]]> HOMO(eV) LUMO(eV) 540 445 19 2.79 2.68 -5.33 -2.79

[0118] Among them, T d represents the thermal decomposition temperature, PL peak represents the photoluminescence peak, FWHM represents the half-maximum width of the emission spectrum, S1 represents the singlet state, T1 represents the triplet state, HOMO represents the highest occupied molecular orbital, and LUMO represents the lowest unoccupied molecular orbital.

[0119] As shown in Table 1, compound 1 exhibits high thermodynamic stability and a narrow emission spectrum, with a peak emission of 445 nm and a half-width of only 19 nm, indicating very pure blue light emission. Furthermore, the small energy difference between S1 and T1 indicates significant thermally activated delayed fluorescence.

[0120] Organic electroluminescent device testing

[0121] Compound 1 synthesized in Example 1 was used in the light-emitting layer of an organic electroluminescent device. Two groups of organic electroluminescent devices were prepared by solution processing (SP) and vacuum evaporation (VE), and then the organic electroluminescent devices were tested.

[0122] The structure of a solution-processed organic electroluminescent device, from bottom to top, is as follows: 1. Conductive glass layer (ITO); 2. Hole injection layer (PEDOT:PSS); 3. Emitting layer; 4. Electron transport layer (TmPyPB); 5. Electron injection layer (LiF); 6. Cathode (Al). The emissive layer is composed of a host material (mCP) and compound 1 (2% by mass).

[0123] The structure of a vacuum-evaporated organic electroluminescent device, from bottom to top, is as follows: 1. Conductive glass layer (ITO); 2. Hole injection layer (PEDOT:PSS); 3. Exciton blocking layer; 4. Emitting layer; 5. Electron transport layer (TmPyPB); 6. Electron injection layer (LiF); 7. Cathode (Al). The emissive layer is composed of a host material (mCBP) and compound 1 (2% by mass).

[0124] The organic electroluminescence performance of the above devices was tested, and the results are shown in Table 2 below.

[0125] Table 2. Performance data of organic electroluminescent devices

[0126]

[0127] The data order is 1 cd m -2 The voltage value at that time.

[0128] As shown in Table 2, the organic electroluminescent devices produced by the above two methods have a low start-up voltage (<5.0V), a high external quantum efficiency (>27%) and a very small CIEy value, realizing the efficient and stable application of electroluminescent devices.

[0129] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A deep blue narrow-band luminescent material, characterized in that: The molecular structure formula of the deep blue narrow-band luminescent material is as follows: Wherein, X is selected from an oxygen atom, and R1, R2, R3, R4, R5, and R6 are independently selected from at least one of a halogen atom and an alkyl group of 1 to 5 carbon atoms.

2. The deep blue narrow-band luminescent material according to claim 1, wherein: The oxygen group atoms include at least one of oxygen, sulfur, selenium, and tellurium; and / or, The halogen atom includes at least one of fluorine, chlorine, bromine and iodine.

3. The deep blue narrow-band luminescent material according to claim 1, wherein: The R1, R2, R3, R4, R5 and R6 are the same.

4. The deep blue narrow-band luminescent material according to any one of claims 1 to 3, characterized in that: The deep blue narrow-band luminescent material includes at least one of the following compounds 1 to 8:

5. A method for preparing a deep blue narrow-band luminescent material, characterized in that: include: reacting compound G with boron tribromide to obtain the deep blue narrow-band luminescent material according to any one of claims 1 to 4; 6. The preparation method according to claim 5, wherein When X in the compound G is selected from oxygen, the compound G is prepared by reacting compound E and compound F; Alternatively, when X in the compound G is selected from at least one of sulfur, selenium, and tellurium, the compound G is prepared by reacting compound K, compound E, and compound F; Wherein, X in the compound K is selected from at least one of sulfur, selenium and tellurium.

7. The preparation method according to claim 6, wherein The compound E is prepared by reacting compound A and compound B to obtain compound C, and then reacting compound C with compound D; 8. The preparation method according to claim 6, wherein The compound K is prepared by reacting compound H and compound I to obtain compound J, and then reacting compound J with compound D; Wherein, X in the compound H, the compound J and the compound K is the same.

9. An electronic device, characterized in that: The electronic device uses the deep blue narrow-band luminescent material according to any one of claims 1 to 4 and / or the deep blue narrow-band luminescent material prepared by the preparation method according to any one of claims 5 to 8.

10. The electronic device according to claim 9, wherein The electronic device includes at least one of an organic electroluminescent device, an organic field effect transistor, an organic sensor, an organic laser, and an organic photovoltaic cell device.

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