An organic compound containing a nitrogen-containing heterocyclic structure and applications thereof

Abstract

The application discloses a compound containing a nitrogen heterocyclic structure and an application thereof, and belongs to the technical field of semiconductor materials. The structure of the compound is shown in general formula (1) or general formula (2). The compound has good stability and electron tolerance, and has good electron injection and hole blocking capabilities. When the compound is used as a material of an organic electroluminescent device, the driving voltage of the device and the service life of the device are both significantly improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, and in particular to an organic compound with a nitrogen-containing heterocyclic structure and its applications. Background Technology

[0002] Organic Light Emission Diodes (OLEDs) technology can be used to manufacture novel display products and lighting products, and is expected to replace existing liquid crystal displays and fluorescent lighting, with a very wide range of applications. OLED devices have a sandwich-like structure, including electrode material layers and organic functional materials sandwiched between different electrode material layers. Various organic functional materials are stacked together according to their intended use to form the OLED light-emitting device. As a current-emitting device, when a voltage is applied to its two electrodes, and an electric field is applied to the positive and negative charges in the organic functional material layers, the positive and negative charges recombine in the light-emitting layer, thus generating OLED electroluminescence.

[0003] Currently, OLED display technology has been applied in smartphones, tablets, and other fields, and will further expand into large-screen applications such as televisions. However, compared with the requirements of actual product applications, the luminous efficiency and lifespan of OLED devices still need further improvement. In order to continuously improve the performance of OLED devices, continuous research and innovation in OLED optoelectronic functional materials are needed to create higher-performance OLED functional materials.

[0004] OLED optoelectronic functional materials used in OLED devices can be broadly categorized into two types based on their applications: charge injection transport materials and luminescent materials. Further, charge injection transport materials can be classified into electron injection transport materials, electron blocking materials, hole injection transport materials, and hole blocking materials. As charge transport materials, they require excellent carrier mobility and high glass transition temperature. In OLED devices, electrons are injected from the cathode and then transported to the host material through the hole blocking layer, where they recombine with holes to generate excitons. Therefore, improving the injection and transport capabilities of the hole blocking layer helps reduce the device driving voltage while achieving high electron-hole recombination efficiency. Thus, the hole blocking layer is crucial, requiring high electron injection and transport capabilities as well as high electron durability.

[0005] With the significant advancements in OLED devices, the performance requirements for materials have also increased. These materials must not only possess excellent stability but also achieve good efficiency and lifetime at low driving voltages. However, current hole-blocking materials suffer from insufficient electron injection and hole-blocking capabilities, as well as inadequate thermal stability. Furthermore, defects in the materials' electron tolerance lead to phase separation or decomposition during device operation, resulting in poor device lifetime. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention provides an organic compound containing a nitrogen heterocyclic structure and its application in organic electroluminescent devices. The nitrogen heterocyclic structure is a triazine group. The compound of this invention bridges the aziridine structure and the spirocyclic group through a specific bridging structure, resulting in excellent electron injection and hole blocking capabilities, as well as good electron durability and material stability. When applied to organic electroluminescent devices, it can effectively reduce the device's operating voltage and improve its lifespan.

[0007] The technical solution of the present invention is as follows: an organic compound containing a nitrogen heterocyclic structure, the structure of which is shown in general formula (1) or general formula (2):

[0008]

[0009]

[0010] In general formula 1 and general formula 2,

[0011] R2 can be independently represented as phenyl, biphenyl, or naphthyl;

[0012] L is independently represented as a single bond or phenyl;

[0013] R1 can be represented independently as general formula a or general formula b;

[0014] n is represented independently as 0 or 1; when n = 1, L represents phenyl.

[0015]

[0016] In general formulas a and b, the asterisks indicate the sites where the ring is fused with the benzene ring;

[0017] Any site of general formula a or general formula b can be connected to the benzene ring or L in general formula (1); any site of general formula a or general formula b can be connected to the benzene ring in general formula (2).

[0018] In general formulas a and b, the phenyl group is attached to the phenyl group in spirofluorene at any position to form naphthalene.

[0019] The preferred compounds containing nitrogen-containing heterocyclic structures are shown in any one of general formulas (1-1) to (1-3):

[0020]

[0021] In general formulas (1-1) to (1-3), the meanings of R1 and R2 are the same as those defined above.

[0022] More preferably, compounds with the nitrogen-containing heterocyclic structure are shown in any one of general formulas (2-1) to (2-4):

[0023]

[0024] In general formulas (2-1) to (2-4), the meanings of R1 and R2 are the same as those defined above.

[0025] Preferably, R1 is as shown in any of the following structures:

[0026]

[0027] Preferably, R1 is as shown in any of the following structures:

[0028]

[0029] Preferably, R2 is as shown in any of the following structures:

[0030]

[0031] The most preferred compound containing the nitrogen-containing heterocyclic structure is any one of the following structures:

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056] The present invention also provides an organic electroluminescent device comprising a first electrode and a second electrode, wherein a multilayer organic thin film layer is provided between the first electrode and the second electrode, and at least one organic thin film layer contains the aforementioned organic compound with a nitrogen-containing heterocyclic structure.

[0057] In a preferred embodiment, the multilayer organic thin film layer includes a hole-blocking layer containing an organic compound with the nitrogen-containing heterocyclic structure.

[0058] The present invention also provides a display element comprising the aforementioned organic electroluminescent device.

[0059] Technical effect

[0060] The compounds of this invention are based on a triazine structure, bridging a nitrogen-containing heterocyclic structure (i.e., a triazine structure) and a spirocyclic group through a specific bridging structure. The substituents are 9,9'-spirobi[9H-fluorene] derivatives or 9,9-dimethylfluorene derivatives. These compounds exhibit good electronic tolerance and stability, as well as excellent electron injection and hole blocking capabilities. Therefore, when used as hole-blocking materials in OLED functional layers, they can effectively reduce the device driving voltage and improve the photoelectric performance and lifetime of OLED devices.

[0061] Because the triazine-structured compounds of this invention can further delocalize the LUMO electron cloud distribution of the material, they can improve the material's electronic tolerance and effectively enhance its electronic stability. Furthermore, the introduction of the 9,9'-spirobi[9H-fluorene] derivative group or the 9,9-dimethylfluorene derivative group in this invention provides excellent steric hindrance, suppressing intermolecular π-π stacking, significantly improving electron injection capability, and reducing the device's driving voltage. Moreover, the presence of the 9,9'-spirobi[9H-fluorene] derivative group or the 9,9-dimethylfluorene derivative group effectively enhances the material's electronic tolerance and stability. Therefore, it can effectively reduce the device's driving voltage and improve its operating life. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the structure of an OLED device using the materials listed in this invention. In the figure, 1 is a transparent substrate layer, 2 is an anode layer, 3 is a hole injection layer, 4 is a hole transport layer, 5 is an electron blocking layer, 6 is a light-emitting layer, 7 is a hole blocking layer, 8 is an electron transport layer, 9 is an electron injection layer, 10 is a cathode layer, and 11 is a CPL layer. Detailed Implementation

[0063] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0064] In this application, unless otherwise stated, HOMO refers to the highest occupied orbital of a molecule, and LUMO refers to the lowest empty orbital of a molecule. Furthermore, in this invention, HOMO and LUMO energy levels are represented by absolute values, and comparisons between energy levels are made by comparing their absolute values. Those skilled in the art know that the larger the absolute value of an energy level, the lower its energy.

[0065] In the accompanying drawings, for clarity, the dimensions of layers and regions may be exaggerated. It will also be understood that when a layer or element is referred to as being "above" another layer or substrate, the layer or element may be directly above that other layer or substrate, or intermediate layers may be present. Furthermore, it will be understood that when a layer is referred to as being "between" two layers, the layer may be the only layer between the two layers, or one or more intermediate layers may be present. The same reference numerals throughout the drawings denote the same elements.

[0066] In this application, the terms "upper" and "lower," used to indicate orientation when describing electrodes, organic electroluminescent devices, and other structures, only indicate orientation in a specific state and do not imply that the related structures can only exist in the stated orientation. Conversely, if the structure can be repositioned, such as by inverting it, the orientation of the structure will change accordingly. Specifically, in this invention, the "lower" side of the electrode refers to the side of the electrode closer to the substrate during fabrication, while the opposite side farther from the substrate is the "upper" side.

[0067] Organic electroluminescent devices

[0068] In another embodiment of this application, an organic electroluminescent device is provided, which includes a first electrode (anode), a second electrode (cathode), and a multilayer organic thin film layer located between the first electrode and the second electrode, wherein at least one organic thin film layer contains the compound with the nitrogen-containing heterocyclic structure.

[0069] In a preferred embodiment of this application, the organic thin film layer includes a hole-blocking layer, wherein the hole-blocking layer comprises a compound with a nitrogen-containing heterocyclic structure according to the present invention.

[0070] In a preferred embodiment of the present invention, the organic electroluminescent device according to the present invention includes a substrate, a first electrode layer (anode layer), an organic thin film layer, and a second electrode layer (cathode layer), wherein the organic thin film layer includes, but is not limited to, a light-emitting layer, a hole injection layer, a hole transport layer, an electron blocking layer, an electron transport layer, an electron injection layer, a second electrode (cathode), and a CPL layer.

[0071] The preferred device structure of this invention adopts a top-emitting form. Preferably, the anode of the organic electroluminescent device of this invention is an electrode with high reflectivity, preferably ITO / Ag / ITO; the cathode is a transparent electrode, preferably a mixed electrode of Mg:Ag = 1:9, thereby forming a microcavity resonance effect, and the device emits light from the Mg:Ag electrode side.

[0072] In a preferred embodiment of the present invention, an organic electroluminescent device is provided, comprising a substrate, an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, a cathode layer, and a CPL layer, wherein the anode is on the substrate, the hole injection layer is on the anode, the hole transport layer is on the hole injection layer, the electron blocking layer is on the hole transport layer, the light-emitting layer is on the hole transport layer, the hole blocking layer is on the light-emitting layer, the electron transport layer is on the hole blocking layer, the electron injection layer is on the electron transport layer, the cathode layer is on the electron injection layer, and the CPL layer is on the cathode layer.

[0073] As the substrate for the organic electroluminescent device of this invention, any substrate commonly used in organic electroluminescent devices can be used. Examples include transparent substrates, such as glass or transparent plastic substrates; opaque substrates, such as silicon substrates; and flexible PI film substrates. Different substrates have different mechanical strengths, thermal stability, transparency, surface smoothness, and water resistance. Their application varies depending on their properties. In this invention, a transparent substrate is preferred. There are no particular limitations on the thickness of the substrate.

[0074] A first electrode (anode) is formed on a substrate. The anode material is preferably a material with a high work function to facilitate hole injection into the organic functional material layer. Non-limiting examples of anode materials include, but are not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO), magnesium (Mg), aluminum (Al), silver (Ag), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), and magnesium-silver (Mg-Ag). The first electrode can have a single-layer structure or a multilayer structure comprising two or more layers. For example, the anode can have a three-layer structure of ITO / Ag / ITO, but is not limited thereto. In addition, the thickness of the anode depends on the material used, typically 50-500 nm, preferably 70-300 nm, and more preferably 100-200 nm.

[0075] Hole injection layer 3, hole transport layer 4 and electron blocking layer 5 can be disposed between anode 2 and light-emitting layer 6.

[0076] The hole injection layer structure consists of a hole injection layer material uniformly or non-uniformly dispersed in a hole transport layer. The hole injection material can be, for example, a P-doped material. The P-doped material can be selected from at least one compound selected from the following: quinone derivatives, such as tetracyanoquinone dimethyl ethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinone dimethyl ethane (F4-TCNQ); metal oxides, such as tungsten oxide or molybdenum oxide; or cyano-containing compounds, such as compounds P1, NDP, and F4-TCNQ shown below:

[0077]

[0078] According to the present invention, P1 is preferably used as the P dopant. The ratio of hole transport layer to P dopant used in the present invention is 99:1-70:30, preferably 99:1-85:15 and more preferably 97:3-87:13, based on mass.

[0079] The thickness of the hole injection layer of the present invention can be 1-100 nm, preferably 2-50 nm, and more preferably 5-20 nm.

[0080] The hole transport layer is preferably made of a material with high hole mobility, which enables holes to be transferred from the anode or hole injection layer to the light-emitting layer. Hole transport materials can be phthalocyanine derivatives, triazole derivatives, triarylmethane derivatives, triarylamine derivatives, oxazole derivatives, oxadiazole derivatives, hydrazone derivatives, stilbene derivatives, pyridinium derivatives, polysilane derivatives, imidazole derivatives, phenylenediamine derivatives, amino-substituted quinone derivatives, styrene-based anthracene derivatives, styrene-based amine derivatives, styrene compounds, fluorene derivatives, spirofluorene derivatives, silazane derivatives, aniline copolymers, porphyrin compounds, carbazole derivatives, polyaryl alkane derivatives, polyphenylene oxide and its derivatives, polythiophene and its derivatives, poly-N-vinylcarbazole derivatives, thiophene oligomers and other conductive polymers, aromatic tertiary amine compounds, and styrene aminations. Compounds, triamines, tetraamines, benzidines, propyne diamine derivatives, p-phenylenediamine derivatives, m-phenylenediamine derivatives, 1,1'-bis(4-diarylaminophenyl)cyclohexane, 4,4'-bis(diarylamine)biphenyls, bis[4-(diarylamino)phenyl]methanes, 4,4”-bis(diarylamino)terphenyls, 4,4'”-bis(diarylamino)tetraphenyls, 4,4'-bis(diarylamino)diphenyl ethers, 4,4'-bis(diarylamino)diphenylsulfanes, bis[4-(diarylamino)phenyl]dimethylmethanes, bis[4-(diarylamino)phenyl]-bis(trifluoromethyl)methanes, or 2,2-diphenylethylene compounds, etc.

[0081] The thickness of the hole transport layer of the present invention can be 5-200 nm, preferably 10-180 nm, and more preferably 20-150 nm.

[0082] The electron blocking layer requires that its triplet (T1) energy level be higher than that of the host material in the emissive layer, thus blocking energy loss from the emissive layer material. The HOMO energy level of the electron blocking layer material should be between that of the hole transport layer material and the host material of the emissive layer, facilitating hole injection from the positive electrode into the emissive layer. Simultaneously, the electron blocking layer material should possess high hole mobility to promote hole transport and reduce the power consumption of the device. The LUMO energy level of the electron blocking layer material should be higher than that of the host material of the emissive layer, serving as an electron blocker; that is, the electron blocking layer material should have a wide bandgap (Eg). Electron blocking layer materials meeting these conditions can be triarylamine derivatives, fluorene derivatives, spirofluorene derivatives, dibenzofuran derivatives, carbazole derivatives, etc. Preferred are triarylamine derivatives, such as N4,N4-bis([1,1'-biphenyl]-4-yl)-N4'-phenylN4'-[1,1':4',1”-terphenyl]-4-yl-[1,1'-biphenyl]-4,4'-diamine; spirofluorene derivatives, such as N-([1,1'-diphenyl]-4-yl)-N-(9,9-dimethyl-9H-furan-2-yl)-9,9'-spirodifluorene-2-amine; dibenzofuran derivatives, such as N,N-bis([1,1'-biphenyl]-4-yl)-3'-(dibenzo[b,d]furan-4-yl)-[1,1'-biphenyl]-4-amine, but not limited thereto.

[0083] According to the present invention, the thickness of the electron blocking layer can be 1-200 nm, preferably 5-150 nm, and more preferably 10-100 nm.

[0084] According to the present invention, the light-emitting layer is located between the first electrode and the second electrode. The material of the light-emitting layer is a material that emits visible light by respectively receiving holes from the hole transport region and electrons from the electron transport region, and combining the received holes and electrons. The light-emitting layer may include a host material and a dopant material. As the host and guest materials of the light-emitting layer of the organic electroluminescent device of the present invention, the host material may be one or a combination of two of the following: anthracene derivatives, quinoxaline derivatives, triazine derivatives, xanthones, diphenyl ketone derivatives, carbazole derivatives, pyridine derivatives, or pyrimidine derivatives. The guest material may be a pyrene derivative, boron derivative, chrysodium derivative, spirofluorene derivative, iridium complex, or platinum complex.

[0085] A hole blocking layer can be placed above the light-emitting layer. The triplet (T1) energy level of the hole blocking layer material is higher than the T1 energy level of the main material of the light-emitting layer, which can block the energy loss of the light-emitting layer material; the HOMO energy level of the material is lower than the HOMO energy level of the main material of the light-emitting layer, which can block holes. At the same time, the hole blocking layer material is required to have high electron injection and hole blocking capabilities to facilitate electron transport and reduce the power consumption of the device.

[0086] The thickness of the hole blocking layer of the present invention can be 2-200 nm, preferably 5-150 nm and more preferably 5-100 nm, but the thickness is not limited to this range.

[0087] An electron transport layer can be disposed above a hole blocking layer. The electron transport layer material is one that readily receives electrons from the cathode and transfers them to the light-emitting layer.

[0088] The electron injection layer material is preferably a metallic Yb with a low work function, which facilitates electron injection into the organic functional material layer. The thickness of the electron injection layer of the present invention can be 0.1-5 nm, preferably 0.5-3 nm, and more preferably 0.8-1.5 nm.

[0089] The second electrode can be a cathode, and the material used to form the cathode can be a material with low work function, such as metals, alloys, conductive compounds, or mixtures thereof. Non-limiting examples of cathode materials can include lithium (Li), ytterbium (Yb), magnesium (Mg), aluminum (Al), calcium (Ca), as well as aluminum-lithium (Al-Li), magnesium-indium (Mg-In), and magnesium-silver (Mg-Ag). The thickness of the cathode depends on the material used, typically 5-100 nm, preferably 7-50 nm, and more preferably 10-25 nm.

[0090] Optionally, to improve the light extraction efficiency of the organic electroluminescent device, a light extraction layer (i.e., a CPL layer) can be added above the second electrode (i.e., the cathode) of the device. According to the principles of optical absorption and refraction, the CPL layer material should have a higher refractive index and a lower absorption coefficient. Any material known in the art can be used as the CPL layer material, such as Alq3. The thickness of the CPL layer is typically 5-300 nm, preferably 20-100 nm, and more preferably 40-80 nm.

[0091] Optionally, the organic electroluminescent device may also include an encapsulation structure. The encapsulation structure may be a protective structure preventing external substances such as moisture and oxygen from entering the organic layer of the organic electroluminescent device. The encapsulation structure may be, for example, a can, such as a glass or metal can; or a thin film covering the entire surface of the organic layer.

[0092] Methods for fabricating organic electroluminescent devices

[0093] The present invention also relates to a method for fabricating the above-mentioned organic electroluminescent device, comprising sequentially laminating a first electrode, a multilayer organic thin film layer, and a second electrode on a substrate. The multilayer organic thin film layer is formed by sequentially laminating a hole transport region, a light-emitting layer, and a hole blocking region on the first electrode from bottom to top. The hole transport region is formed by sequentially laminating a hole injection layer, a hole transport layer, and an electron blocking layer on the first electrode from bottom to top, and the hole blocking region is formed by sequentially laminating a hole blocking layer, an electron transport layer, and an electron injection layer on the light-emitting layer from bottom to top. Optionally, a CPL layer may also be laminated on the second electrode to improve the light extraction efficiency of the organic electroluminescent device.

[0094] Regarding lamination, methods such as vacuum deposition, vacuum evaporation, spin coating, casting, LB method, inkjet printing, laser printing, or LITI can be used, but are not limited to these. Among them, vacuum evaporation refers to heating the material and depositing it onto the substrate in a vacuum environment.

[0095] In this invention, vacuum evaporation is preferably used to form the various layers, wherein the vapor deposition process can be carried out at a temperature of about 100-500°C for about 10... -8 -10 -2 The vacuum degree and about Vacuum evaporation is performed at a rate of [missing information]. The vacuum level is preferably 10 [missing information]. -6 -10 -2 Torr, more preferably 10 -5 -10 -3 Torr. The rate is approximately More preferably, about

[0096] In addition, it should be noted that the materials used to form each layer described in this invention can be used as a single layer by forming a film on their own, or they can be used as a single layer by mixing with other materials to form a film. They can also be a stacked structure between layers that are formed on their own, a stacked structure between layers that are formed by mixing, or a stacked structure between layers that are formed on their own and layers that are formed by mixing.

[0097] Display elements

[0098] The present invention also relates to a display device including the aforementioned organic electroluminescent devices, particularly a flat panel display device. In a preferred embodiment, the display device may include one or more of the aforementioned organic electroluminescent devices, and in the case of multiple devices, the devices are stacked laterally or vertically. The display device may also include at least one thin-film transistor. The thin-film transistor may include a gate electrode, a source electrode and a drain electrode, a gate insulating layer and an active layer, wherein one of the source electrode and the drain electrode may be electrically connected to a first electrode of the organic electroluminescent device. The active layer may include crystalline silicon, amorphous silicon, organic semiconductor or oxide semiconductor, but is not limited thereto.

[0099] Example

[0100] I. Compound Preparation Examples

[0101] All raw materials involved in the synthesis embodiments of the present invention can be purchased from the market or obtained by conventional preparation methods in the art;

[0102] The preparation route and synthesis process of intermediate A1 are shown below:

[0103]

[0104] Under nitrogen protection, in a round-bottom flask, raw material O1 (30 mmol), raw material P1 (40 mmol), K2CO3 (100 mmol), tetrahydrofuran (180 mL), and water (60 mL) were added sequentially. Nitrogen gas was purged for 60 min to replace the air. Pd(PPh3)4 (0.6 mmol) was added, and the mixture was heated under reflux for 12 h under nitrogen protection. TCL analysis of the reaction solution showed that raw material O1 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 150 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate Q1. LC-MS: Measured value: 266.86 ([M+H) + ), Precision quality: 265.95.

[0105] Under nitrogen protection, in a round-bottom flask, raw material R1 (30 mmol) and diethyl ether (160 mL) were added sequentially. The mixture was cooled to -78 °C, and nitrogen was purged for 40 min to replace the air. A 1.6 mol / L hexane solution of n-butyllithium (40 mmol) was slowly added, and the reaction was maintained at -78 °C for 3 h. Then, trimethyl borate (40 mmol) was added, and the reaction was maintained at -78 °C for 1.5 h. The mixture was then allowed to react at room temperature for 18 h. TCL analysis of the reaction solution showed that raw material R1 had reacted completely. After the reaction was complete, a dilute hydrochloric acid solution (50 mL) was added to the reaction system, and the organic solvent was removed by rotary evaporation. The residue was filtered to obtain a white solid intermediate S1. LC-MS: Measured value: 278.19 ([M+H)). + ); Precision quality: 277.10.

[0106] Under nitrogen protection, intermediates Q1 (15 mmol), S1 (20 mmol), K2CO3 (50 mmol), tetrahydrofuran (200 mL), and water (70 mL) were added sequentially to a round-bottom flask. Nitrogen gas was purged for 45 min to replace the air. Pd(PPh3)4 (0.3 mmol) was added, and the mixture was heated under reflux for 16 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate Q1 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 200 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (50 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate A1. LC-MS: Measured value: 420.20 ([M+H) + ); Precision quality: 419.12.

[0107] The preparation route and synthesis process of intermediate A2 are shown below:

[0108]

[0109] Under nitrogen protection, in a round-bottom flask, the following reactants were added sequentially: O2 (30 mmol), P2 (40 mmol), K2CO3 (90 mmol), tetrahydrofuran (180 mL), and water (80 mL). Nitrogen gas was purged for 65 min to replace the air. Pd(PPh3)4 (0.6 mmol) was then added, and the mixture was heated under reflux for 12 h under nitrogen protection. TCL analysis of the reaction solution showed that the O2 reactant had completely reacted. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 160 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate Q2. LC-MS: Measured value: 342.91 ([M+H) + Precision quality: 341.98.

[0110] Under nitrogen protection, intermediates Q2 (20 mmol), S1 (30 mmol), K2CO3 (60 mmol), tetrahydrofuran (200 mL), and water (70 mL) were added sequentially to a round-bottom flask. The air was replaced by nitrogen purging for 55 min. Pd(PPh3)4 (0.3 mmol) was added, and the mixture was heated under reflux for 16 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate Q2 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 250 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate A2. LC-MS: Measured value: 496.23 ([M+H) + ); Precision quality: 495.15.

[0111] The preparation route and synthesis process of intermediate A3 are shown below:

[0112]

[0113] Under nitrogen protection, in a round-bottom flask, raw material R3 (30 mmol) and diethyl ether (170 mL) were added sequentially. The mixture was cooled to -80 °C, and nitrogen was purged for 60 min to replace the air. A 1.6 mol / L hexane solution of n-butyllithium (40 mmol) was slowly added, and the reaction was maintained at -80 °C for 4 h. Then, trimethyl borate (40 mmol) was added, and the reaction was maintained at -80 °C for 1.5 h. The mixture was then allowed to react at room temperature for 20 h. TCL analysis of the reaction solution showed that raw material R3 had reacted completely. After the reaction was complete, a dilute hydrochloric acid solution (60 mL) was added to the reaction system, and the organic solvent was removed by rotary evaporation. The residue was filtered to obtain a white solid intermediate S3. LC-MS: Measured value: 328.14 ([M+H)). + ), Precision quality: 327.12.

[0114] Under nitrogen protection, intermediates Q1 (20 mmol), S3 (30 mmol), K2CO3 (60 mmol), tetrahydrofuran (200 mL), and water (70 mL) were added sequentially to a round-bottom flask. The air was replaced by nitrogen purging for 55 min. Pd(PPh3)4 (0.3 mmol) was added, and the mixture was heated under reflux for 16 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate Q1 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 250 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate A3. LC-MS: Measured value: 470.29 ([M+H) + ); Precision quality: 469.13.

[0115] The preparation route and synthesis process of intermediate A4 are shown below:

[0116]

[0117] Under nitrogen protection, intermediates Q2 (20 mmol), S3 (35 mmol), K2CO3 (65 mmol), tetrahydrofuran (200 mL), and water (75 mL) were added sequentially to a round-bottom flask. Nitrogen gas was purged for 55 min to replace the air. Pd(PPh3)4 (0.3 mmol) was added, and the mixture was heated under reflux for 17 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate Q2 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 250 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate A4. LC-MS: Measured value: 546.29 ([M+H) + Precision quality: 545.17.

[0118] The preparation route and synthesis process of intermediate A5 are shown below:

[0119]

[0120] Under nitrogen protection, in a round-bottom flask, raw material R5 (40 mmol) and diethyl ether (200 mL) were added sequentially. The mixture was cooled to -80 °C, and nitrogen was purged for 80 min to replace the air. A 1.6 mol / L hexane solution of n-butyllithium (40 mmol) was slowly added, and the reaction was maintained at -80 °C for 4.5 h. Then, trimethyl borate (40 mmol) was added, and the reaction was maintained at -80 °C for 1.5 h. The mixture was then allowed to react at room temperature for 24 h. TCL analysis of the reaction solution showed that raw material R5 had reacted completely. After the reaction was complete, a dilute solution of hydrochloric acid (60 mL) was added to the reaction system, and the organic solvent was removed by rotary evaporation. The residue was filtered to obtain a white solid intermediate S5. LC-MS: Measured value: 354.35 ([M+H)). + Precision quality: 353.13.

[0121] Under nitrogen protection, intermediates Q1 (18 mmol), S5 (33 mmol), K2CO3 (65 mmol), tetrahydrofuran (200 mL), and water (75 mL) were added sequentially to a round-bottom flask. The mixture was purged with nitrogen for 75 min to replace the air. Pd(PPh3)4 (0.3 mmol) was then added, and the mixture was heated under reflux for 19 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate Q2 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 300 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate A5. LC-MS: Measured value: 496.07 ([M+H) + Precision quality: 495.15.

[0122] The preparation route and synthesis process of intermediate A6 are shown below:

[0123]

[0124] Under nitrogen protection, in a round-bottom flask, the following reactants were added sequentially: O6 (30 mmol), P2 (45 mmol), K2CO3 (90 mmol), tetrahydrofuran (180 mL), and water (80 mL). Nitrogen gas was purged for 75 min to replace the air. Pd(PPh3)4 (0.6 mmol) was then added, and the mixture was heated under reflux for 15 h under nitrogen protection. TCL analysis of the reaction solution showed that the reactant O6 had completely reacted. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 160 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate Q6. LC-MS: Measured value: 342.83 ([M+H) + Precision quality: 341.98.

[0125] Under nitrogen protection, intermediates Q6 (20 mmol), S1 (35 mmol), K2CO3 (65 mmol), tetrahydrofuran (200 mL), and water (75 mL) were added sequentially to a round-bottom flask. The mixture was purged with nitrogen for 85 min to replace the air, and Pd(PPh3)4 (0.3 mmol) was added. The mixture was heated under reflux for 20 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate Q6 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, and the solvent was removed by rotary evaporation. The residue was dissolved in 300 mL of dichloromethane, washed with 120 mL of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 mL * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate A6. LC-MS: Measured value: 496.07 ([M+H) + Precision quality: 495.15.

[0126] The preparation route and synthesis process of intermediate A7 are shown below:

[0127]

[0128] Intermediate A7 was prepared using the same synthetic method as intermediate A1, except that raw material Q7 was used instead of intermediate Q1. LC-MS: Measured value: 420.35 ([M+H)) + ), Precision quality: 419.12.

[0129] The preparation route and synthesis process of intermediate A8 are shown below:

[0130]

[0131] Intermediate Q8 was prepared using the same synthetic method as intermediate Q6, except that raw material P8 was used instead of intermediate P2. LC-MS: Measured value: 342.90 ([M+H)). + Precision quality: 341.98.

[0132] Intermediate A8 was prepared using the same synthetic method as intermediate A6, except that intermediate Q8 was used instead of intermediate Q6. LC-MS: Measured value: 496.22 ([M+H]). + Precision quality: 495.15.

[0133] The preparation route and synthesis process of intermediate A9 are shown below:

[0134]

[0135] Intermediate Q9 was prepared using the same synthetic method as intermediate Q2, except that raw material P8 was used instead of intermediate P2. LC-MS: Measured value: 342.87 ([M+H)) + Precision quality: 341.98.

[0136] Intermediate A9 was prepared using the same synthetic method as intermediate A2, except that intermediate Q2 was replaced with intermediate Q9. LC-MS: Measured value: 496.30 ([M+H)). + Precision quality: 495.15.

[0137] The preparation route and synthesis process of intermediate B1 are shown below:

[0138]

[0139] Under nitrogen protection, in a round-bottom flask, 10 mmol of starting material T1, 12 mmol of pinacol diborate, KOAC (50 mmol), and dioxane (120 ml) were added sequentially. Nitrogen was purged for 40 min to replace the air. Pd(PPh3)4 (0.2 mmol) was added, and the mixture was heated under nitrogen protection and refluxed for 12 h. TCL analysis of the reaction solution showed that intermediate T1 had completely reacted. After the reaction was complete, the reaction system was naturally cooled to room temperature, poured into a separatory funnel, shaken, and allowed to separate into layers. The aqueous phase was extracted with dichloromethane (50 ml * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane, yielding intermediate B1. LC-MS: Measured value: 493.42 ([M+H) + Precision mass: 492.23.

[0140] The preparation route and synthesis process of intermediate B2 are shown below:

[0141]

[0142] Under nitrogen protection, in a round-bottom flask, 15 mmol of starting material T2, 20 mmol of pinacol diborate, KOAC (50 mmol), and dioxane (120 ml) were added sequentially. Nitrogen was purged for 60 min to replace the air. Pd(PPh3)4 (0.3 mmol) was added, and the mixture was heated under reflux for 16 h under nitrogen protection. TCL analysis of the reaction solution showed that intermediate T2 had completely reacted. After the reaction was complete, the reaction system was naturally cooled to room temperature, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 ml * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane, yielding intermediate B2. LC-MS: Measured value: 493.36 ([M+H) + Precision mass: 492.23.

[0143] The preparation route and synthesis process of intermediate B3 are shown below:

[0144]

[0145] Under nitrogen protection, in a round-bottom flask, 16 mmol of starting material T3, 25 mmol of pinacol diborate, KOAC (70 mmol), and dioxane (140 ml) were added sequentially. Nitrogen was purged for 60 min to replace air. Pd(PPh3)4 (0.4 mmol) was then added, and the mixture was heated under nitrogen protection and refluxed for 16 h. TCL analysis of the reaction solution showed that intermediate T3 had completely reacted. After the reaction was complete, the reaction system was naturally cooled to room temperature, poured into a separatory funnel, shaken, and allowed to separate into layers. The aqueous phase was extracted with dichloromethane (60 ml * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane, yielding intermediate B3. LC-MS: Measured value: 493.47 ([M+H) + Precision mass: 492.23.

[0146] The preparation route and synthesis process of intermediate B4 are shown below:

[0147]

[0148] Under nitrogen protection, in a round-bottom flask, 18 mmol of starting material T4, 30 mmol of pinacol diborate, KOAC (70 mmol), and dioxane (140 ml) were added sequentially. Nitrogen was purged for 80 min to replace air. Pd(PPh3)4 (0.4 mmol) was then added, and the mixture was heated under nitrogen protection and refluxed for 18 h. TCL analysis of the reaction solution showed that intermediate T4 had completely reacted. After the reaction was complete, the reaction system was naturally cooled to room temperature, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (60 ml * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane, yielding intermediate B4. LC-MS: Measured value: 493.48 ([M+H) + Precision mass: 492.23.

[0149] Example 1: Synthesis of Compound 3

[0150]

[0151] Under nitrogen protection, intermediate A1 (20 mmol), intermediate B1 (28 mmol), K2CO3 (60 mmol), tetrahydrofuran (100 mL), and water (50 mL) were added sequentially to a round-bottom flask. Nitrogen gas was purged for 50 min to replace the air. Palladium acetate (0.20 mmol) and 2-dicyclohexylphosphine-2',4',6'-triisopropylbiphenyl (0.40 mmol) were then added. The mixture was heated under nitrogen protection and refluxed for 18 h. TCL analysis of the reaction solution showed that intermediate A1 reacted completely. After the reaction was completed, the reaction system was naturally cooled to room temperature, the solvent was removed by rotary evaporation, the residue was dissolved in 180 ml of dichloromethane, washed with 180 ml of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (100 ml * 3), the organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was removed by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain compound 3.

[0152] Other compounds were prepared using a synthetic method similar to that of compound 3, with the starting materials or intermediates used as shown in Table 1.

[0153] Table 1

[0154]

[0155]

[0156]

[0157]

[0158] II. Device Fabrication Examples

[0159] The following describes in detail the application effects of the compounds synthesized according to the present invention as electron transport materials in devices through device Examples 1-22 and device Comparative Examples 1-16. Device Examples 1-22 and Comparative Examples 1-16 are manufactured using the same process, substrate and electrode materials, and the electrode film thickness is also consistent. The only difference is the material of the 8-hole blocking layer in the device. The device layer structure is shown in Table 2, and the performance test results of each device are shown in Table 3.

[0160] The molecular structural formulas of the relevant materials are shown below:

[0161]

[0162]

[0163] The structures of compounds HB-1, HB-2, HB-3, HB-4, HB-5, HB-6, HB-7, HB-8, HB-9, HB-10, HB-11, HB-12, HB-13, HB-14, HB-15, and HB-16 are shown above. These materials are commercially available or can be obtained using conventional synthetic methods in this field.

[0164] Device Example 1

[0165] The specific preparation process is as follows:

[0166] like Figure 1 As shown, the transparent substrate layer 1 is transparent glass, and the anode layer 2 is Ag (100nm). On the anode layer 2, HT-1 and P-1 with a thickness of 10nm are deposited using a vacuum evaporation apparatus as a hole injection layer 3, with a mass ratio of HT-1 to P-1 of 97:3. Next, HT-1 with a thickness of 117nm is deposited as a hole transport layer 4. Subsequently, EB-1 with a thickness of 10nm is deposited as an electron blocking layer 5. After the electron blocking materials are deposited, the light-emitting layer 6 of the OLED light-emitting device is fabricated. Its structure includes BH-1 as the host material and BD-1 as the dopant material, with a doping ratio of 3% by weight, and a light-emitting layer thickness of 20nm. After the light-emitting layer 6, compound 3 is deposited with a thickness of 8nm as a hole blocking layer 7. ET-1 and Liq are then deposited on top of the hole blocking layer 7, with a mass ratio of ET-1 to Liq of 1:1. The vacuum-deposited film of this material is 30 nm thick, and this layer is the electron transport layer 8. On the electron transport layer 8, a 1 nm thick LiF layer is fabricated using a vacuum evaporation apparatus; this layer is the electron injection layer 9. On the electron injection layer 9, a 16 nm thick Mg:Ag electrode layer is fabricated using a vacuum evaporation apparatus, with a Mg to Ag mass ratio of 1:9; this layer is used as the cathode layer 10. On the cathode layer 10, a 65 nm thick CP-1 layer is vacuum-deposited as the CPL layer 11.

[0167] Device Examples 2-22 and Device Comparative Examples 1-16 were prepared in a similar manner to Device Example 1, and all used transparent glass as the substrate and Ag (100 nm) as the anode, except that the parameters in Table 2 below were used.

[0168] Table 2

[0169]

[0170]

[0171]

[0172] III. Device Testing Examples

[0173] The devices fabricated in Part II were tested, including their drive voltage and LT95 lifetime. The voltage was measured using an IVL (current-voltage-luminance) testing system (Suzhou Fushida Scientific Instruments Co., Ltd.), with a current density of 10 mA / cm². 2 LT95 refers to the time it takes for the device's brightness to decay to 95% of its initial brightness, measured at a current density of 50 mA / cm². 2 The lifetime testing system was the EAS-62C OLED device lifetime tester from System Technology Inc., Japan. The high-temperature lifetime test temperature was 85℃. LT80 refers to the time it takes for the device brightness to decay to 80% at a specific brightness level. The test results are shown in Table 3 below.

[0174] Table 3

[0175]

[0176]

[0177] As can be seen from the device test data results in Table 3 above, compared with the comparative devices using HB-1, HB-2, HB-3, HB-4, HB-5, HB-6, HB-7, HB-8, HB-9, HB-10, HB-11, HB-12, HB-13, HB-14, HB-15, and HB-16 as hole blocking layer materials, the device prepared using the compound of the present invention as the hole blocking layer material has a significantly lower driving voltage and a longer device lifespan. For example, its lifespan is basically more than 1.15 times that of the comparative devices 1-16.

[0178] The comparative compounds HB-1, HB-2, HB-3, HB-4, HB-5, HB-6, HB-7, HB-8, HB-9, HB-10, HB-11, HB-12, HB-13, HB-14, HB-15, and HB-16 used in the comparative examples have structural formulas similar to those of the present invention. However, by changing the intermediate bridging group or substituent group, the compounds of the present invention achieve better technical effects as hole blocking materials than the comparative compounds.

[0179] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A compound having a nitrogen-containing heterocyclic structure, characterized by, The structure of the compound is shown in general formula (1) or general formula (2): Formula (1) Formula (2) In general formula 1 and general formula 2, R2 can be independently represented as phenyl, biphenyl, or naphthyl; L is independently represented as a single bond or phenyl; R1 can be represented independently as general formula a or general formula b; n is represented independently as 0 or 1; when n=1, L represents phenyl. General formula a General formula b In general formulas a and b, the asterisks indicate the sites where the ring is fused with the benzene ring; Any site of general formula a or general formula b can be connected to the benzene ring or L in general formula (1); any site of general formula a or general formula b can be connected to the benzene ring in general formula (2).

2. The compound according to claim 1, characterized in that, The structure of the compound is shown in any one of general formulas (1-1) to (1-3): General formula (1-1) General formula (1-2) General formula (1-3) In general formulas (1-1) to (1-3), the meanings of R1 and R2 are the same as those defined in claim 1.

3. The compound according to claim 1 or 2, characterized in that, The structure of the compound is shown in any one of general formulas (2-1) to (2-4): General formula (2-1) General formula (2-2) General formula (2-3) General formula (2-4) In general formulas (2-1) to (2-4), the meanings of R1 and R2 are the same as those defined in claim 1.

4. The compound according to claim 1, characterized in that, R1 can be any of the following structures: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 5. The compound according to claim 1, characterized in that, R1 can be any of the following structures: 、 、 、 、 、 、 、 、 、 、 、 。 6. The compound according to claim 1, characterized in that, R2 can be any of the following structures: 、 、 、 、 、 。 7. The compound according to claim 1, characterized in that, The specific structure of the compound is any one of the following structures: 。 8. An organic electroluminescent device, comprising a first electrode and a second electrode, wherein a multilayer organic thin film layer is disposed between the first electrode and the second electrode, characterized in that, At least one organic thin film layer contains a compound with a nitrogen-containing heterocyclic structure as described in any one of claims 1 to 7.

9. The organic electroluminescent device according to claim 8, characterized in that, The multilayer organic thin film layer includes a hole-blocking layer, which contains a compound with a nitrogen-containing heterocyclic structure as described in any one of claims 1 to 7.

10. A display element, characterized in that, The display element comprises the organic electroluminescent device as described in claim 8 or 9.

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