An aromatic amine compound and an organic electroluminescence device comprising the same

Abstract

The application discloses an aromatic amine compound and an organic electroluminescent device containing the same, and belongs to the technical field of semiconductor materials. The structure of the aromatic amine compound is shown in general formula (1). The organic compound has excellent hole mobility and exciton blocking capacity under high current density. When the aromatic amine compound is used to form a light-emitting auxiliary layer material of the organic electroluminescent device, the device efficiency can be improved and the service life can be prolonged, and the device efficiency is improved significantly.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, and in particular to an aromatic amine compound and an organic electroluminescent device containing the same. Background Technology

[0002] In organic light-emitting diodes (OLEDs), charge carriers (holes and electrons) are injected into the device through two electrodes under the drive of an electric field, and recombine to emit light in the organic light-emitting layer. High-performance OLEDs require various organic functional materials to possess excellent photoelectric properties. For example, as charge transport materials, they must have good carrier mobility. The hole injection and transport layer materials used in existing OLEDs have relatively weak injection and transport characteristics. The hole injection and transport rates are mismatched with the electron injection and transport rates, leading to a large shift in the recombination region, which is detrimental to device stability. Therefore, adjusting the balance between holes and electrons and regulating the recombination region has always been an important research topic in this field.

[0003] Blue organic light-emitting diodes (OLEDs) have always been a weak point in the development of full-color OLEDs. To date, the efficiency and lifetime of blue light devices have been difficult to improve comprehensively. Therefore, improving the performance of these devices remains a crucial issue and challenge in this field. Currently, most blue light-emitting substrates used in the market are electron-biased. At low current densities, preferential hole injection alleviates the pressure on the hole transport side to some extent. However, as the current density increases, the amount of electron injection increases, causing the recombination region to shift towards the hole side, increasing the pressure on the hole side. To prevent excitons from being transferred to the hole side, the luminescent auxiliary layer material must effectively block excitons and efficiently transport holes to the luminescent layer. Currently, most luminescent auxiliary layer materials are traditional aromatic amine structures with carbazole or dibenzofuran groups as branching chains. The exciton resistance stability of these structures still cannot meet the requirements, and the hole mobility at high current densities needs to be improved to ensure carrier balance in the luminescent layer and prevent the recombination region from shifting towards the hole transport side due to insufficient holes, leading to reduced device efficiency and shorter lifetime. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, the applicant of this invention provides an aromatic amine compound. This compound exhibits excellent hole mobility and exciton blocking ability at high current densities. When the aromatic amine compound of this invention is used to form the light-emitting auxiliary layer material of an organic electroluminescent device, it can simultaneously show the effects of improved device efficiency and extended lifetime, especially the significant improvement in device efficiency.

[0005] The technical solution of the present invention is as follows: an aromatic amine compound, the structure of which is shown in general formula (1):

[0006]

[0007] In general formula (1), R is selected from the structure shown in formula (A), formula (B), formula (C) or formula (D);

[0008]

[0009] R1 represents phenyl, naphthyl, biphenyl, dibenzofuranyl or dibenzothiophene, and when R1 represents dibenzofuranyl or dibenzothiophene, R is not selected from formula (A);

[0010] The L represents phenylene, biphenylene, or naphthylene.

[0011] In a preferred embodiment, the structure of the compound is shown in general formula (1-1):

[0012]

[0013] R1 represents phenyl, naphthyl, biphenyl, phenyl-substituted naphthyl, dibenzofuranyl, or dibenzothiopheneyl;

[0014] The L represents phenylene, biphenylene, or naphthylene.

[0015] In a preferred embodiment, the structure of the compound is shown in general formula (1-2);

[0016]

[0017] R1 represents phenyl, naphthyl, biphenyl, or phenyl-substituted naphthyl;

[0018] The L represents phenylene, biphenylene, or naphthylene.

[0019] In a preferred embodiment, the structure of the compound is shown in general formulas (1-3);

[0020]

[0021] R1 represents phenyl, naphthyl, biphenyl, phenyl-substituted naphthyl, dibenzofuranyl, or dibenzothiophene; L represents phenylene, biphenylene, or naphthylene.

[0022] In a preferred embodiment, the structure of the compound is shown in general formulas (1-4):

[0023]

[0024] The L represents phenylene, biphenylene, or naphthylene.

[0025] In a preferred embodiment, the structure of the compound is shown in general formulas (1-5);

[0026]

[0027] The L represents a direct bond, phenylene, or naphthylene.

[0028] In a preferred embodiment, the specific structure of the compound is any one of the following structures:

[0029]

[0030]

[0031]

[0032]

[0033] An organic electroluminescent device comprises, in sequence, an anode, a hole transport region, a light-emitting region, an electron transport region, and a cathode, wherein the hole transport region contains the aromatic amine compound.

[0034] In a preferred embodiment, the hole transport region includes a hole injection layer, a hole transport layer, and a light-emitting auxiliary layer, wherein the light-emitting auxiliary layer contains the aromatic amine compound.

[0035] In a preferred embodiment, the electron transport region comprises a nitrogen heterocyclic compound represented by general formula (4):

[0036]

[0037] Ar5, Ar6, and Ar7 are independently selected from substituted or unsubstituted C6-C. 30 Aryl, substituted or unsubstituted C3-C containing one or more heteroatoms 30 One of the heterocyclic groups;

[0038] L3 represents C6-C with a single bond, substitution, or no substitution. 30 aryl, substituted or unsubstituted C3-C containing one or more heteroatoms 30 One of the heterocyclic groups; X1, X2, and X3 independently represent N or CH, and at least one of X1, X2, and X3 represents N;

[0039] The heteroatoms are selected from N, O, or S;

[0040] The substituents used for the substituent groups are one or more of the following: deuterium, phenyl, naphthyl, biphenyl, dibenzofuranyl, dibenzothiophenyl, pyridyl, or pyrimidinyl.

[0041] The beneficial technical effects of this invention are as follows:

[0042] (1) The special combination and connection between the aromatic amine compound groups of the present invention gives the compound of the present invention a better exciton blocking ability, so that the excitons are better localized in the light-emitting region, ensuring a high exciton concentration in the light-emitting region, thereby improving the luminescence efficiency.

[0043] The compounds in this invention application have superior exciton blocking ability and hole mobility at high current density. When applied to devices, they can improve device efficiency while exhibiting excellent device lifetime.

[0044] (2) The connection mode and specific types of groups of the compound in this application ensure that energy levels with differentiated charge carrier conduction are formed in the aromatic amine molecular structure, thereby forming different charge carrier conduction channels. This is beneficial to the charge carrier injection and conduction between materials with different energy levels, and thus beneficial to obtaining the interface stability between the compound in this application and the adjacent layer material, thereby beneficial to obtaining good driving lifetime of the application device.

[0045] (3) The compound structure of this invention is stable. Even when hole injection becomes stronger under high current density, it can still conduct holes to the light-emitting layer through different carrier conduction channels, thus ensuring the hole concentration under high current density and improving the luminous efficiency of the device.

[0046] (4) The structural features of the compound in this application are beneficial to increasing the glass transition temperature of the molecule and reducing the vapor deposition temperature of the molecule. In other words, even if the molecular weight of the structure is relatively high, it can ensure a low vapor deposition temperature. This excellent performance is not only beneficial to the thermal vapor deposition of the material and the control of the thermal decomposition rate of the material, but also improves the stability of the material in device applications.

[0047] The organic functional materials constituting OLED devices include not only hole injection conducting materials but also electron injection conducting materials and light-emitting layer materials. Good device performance requires a good carrier balance. Therefore, to achieve optimal device performance, aromatic amine compounds with the characteristic structures described in this invention also need to be paired with specific electronic materials. Based on the inventors' in-depth research, the electronic materials are preferably materials containing azirbenzene structural features, such as triazine, pyridine, pyrazine, or compounds containing these characteristic groups. The aromatic amine compounds of this invention, when combined with azirbenzene ring-based electron transport materials, facilitate an optimal balance between electrons and holes, resulting in high efficiency and excellent lifetime. Attached Figure Description

[0048] Figure 1This is a cross-sectional view of the organic electroluminescent device of the present invention.

[0049] In the figure, 1 represents the substrate layer; 2 represents the anode layer; 3 represents the hole injection layer; 4 represents the hole transport layer; 5 represents the light-emitting auxiliary layer; 6 represents the light-emitting layer; 7 represents the hole blocking layer; 8 represents the electron transport layer; 9 represents the electron injection layer; 10 represents the cathode layer; and 11 represents the capping layer. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0051] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0052] In this invention, when a layer or element is referred to as being "above" another layer or substrate, the layer or element may be located directly above the other layer or substrate, or there may be intermediate layers. 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 there may be one or more intermediate layers. The same reference numerals throughout the drawings denote the same elements.

[0053] In this invention, the terms "upper," "lower," "top," and "bottom," used to describe electrodes, organic electroluminescent devices, and other structures, indicate orientation only in a specific state and do not imply that the structure can only exist in that orientation. Conversely, if the structure can be repositioned, such as by inverting it, the orientation of the structure changes accordingly. Specifically, in this invention, the "bottom" or "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 "top" or "upper" side.

[0054] In this specification, the term "substitution" means that one or more hydrogen atoms on a specified atom or group are replaced by a specified group, provided that the normal valence of the specified atom is not exceeded under the existing conditions.

[0055] In this specification, hole characteristics refer to the characteristics that allow holes formed in the anode to be easily injected into and transported in the light-emitting layer when an electric field is applied, due to conductivity characteristics at the highest occupied molecular orbital (HOMO) level.

[0056] In this specification, electronic characteristics refer to the characteristics that allow electrons formed in the cathode to be readily injected into and transported in the light-emitting layer when an electric field is applied, and which are attributed to conductivity characteristics based on the lowest unoccupied molecular orbital (LUMO) level.

[0057] The organic electroluminescent device of the present invention can be a bottom-emitting organic electroluminescent device, a top-emitting organic electroluminescent device, or a multilayer organic electroluminescent device, and there is no specific limitation thereto.

[0058] In the organic electroluminescent device of this invention, any substrate commonly used in organic electroluminescent devices can also be used. Examples include transparent substrates, such as glass or transparent plastic substrates; opaque substrates, such as silicon substrates; and flexible polyimide (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.

[0059] anode

[0060] Preferably, the anode can be formed on the substrate. In this invention, the anode and cathode are opposite each other. The anode can be made of a conductor with a high work function to facilitate hole injection, and can be, for example, a metal such as nickel, platinum, copper, zinc, silver or alloys thereof; a metal oxide such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); a combination of metal and metal oxide, such as ZnO and Al or ITO and Ag; a conductive polymer such as poly(3-methylthiophene), poly(3,4-(ethylene-1,2-dioxy)thiophene), and polyaniline, but is not limited thereto. The thickness of the anode depends on the material used, typically 50-500 nm, preferably 70-300 nm, and more preferably 100-200 nm. In this invention, a combination of metal and metal oxide, ITO and Ag, is preferred.

[0061] cathode

[0062] The cathode can be made of a conductor with a low work function to facilitate electron injection, and can be, for example, a metal or alloy thereof, such as magnesium, calcium, sodium, potassium, titanium, indium, aluminum, silver, tin, and combinations thereof; multilayer materials, such as LiF / Al, Li2O / Al, and BaF2 / Ca, but not limited thereto. The thickness of the cathode depends on the material used, typically 10-50 nm, preferably 15-20 nm.

[0063] Light-emitting area

[0064] In this invention, the light-emitting region can be disposed between the anode and the cathode, and can include at least one host material and at least one guest material. Both the host and guest materials of the light-emitting region in the organic electroluminescent device of this invention can be light-emitting layer materials known in the prior art for organic electroluminescent devices. The host material can be, for example, a thiazole derivative, a benzimidazole derivative, a polydialkylfluorene derivative, or 4,4'-bis(9-carbazolyl)biphenyl (CBP). The host material can be a compound containing anthracene groups. The guest material can be, for example, a quinacridone, coumarin, rubrene, perylene and its derivatives, benzopyran derivatives, rhodamine derivatives, or aminostyrene derivatives.

[0065] In a preferred embodiment of the present invention, the luminescent region contains one or two host material compounds.

[0066] In a preferred embodiment of the present invention, the luminescent region contains two host material compounds, and the two host material compounds form an excitocomplex.

[0067] In a preferred embodiment of the present invention, the host material of the luminescent region is selected from one or more of the following compounds BH-1-BH-11:

[0068]

[0069]

[0070] In this invention, the luminescent region may contain phosphorescent or fluorescent guest materials to improve the fluorescence or phosphorescence properties of the organic electroluminescent device. Specific examples of phosphorescent guest materials include metal complexes of iridium, platinum, etc., while those commonly used in the art can be used for fluorescent guest materials. In a preferred embodiment of this invention, the guest material used in the luminescent film layer is selected from one of the following compounds: BD-1 to BD-10.

[0071]

[0072] In the light-emitting region of the present invention, the ratio of the host material to the guest material is 99:1-70:30, preferably 99:1-85:15 and more preferably 97:3-87:13, based on mass.

[0073] The thickness of the light-emitting region can be 10-50 nm, preferably 15-30 nm, but the thickness is not limited to this range.

[0074] Hole transport region

[0075] In the organic electroluminescent device of the present invention, a hole transport region is disposed between the anode and the light-emitting region, and includes a hole injection layer, a hole transport layer and a light-emitting auxiliary layer.

[0076] Hole injection layer

[0077] The hole injection material used in the hole injection layer (also known as the anode interface buffer layer) is a material capable of fully accepting holes from the anode at low voltages, and the highest occupied molecular orbital (HOMO) of the hole injection material is preferably a value between the work function of the anode material and the HOMO of the adjacent organic material layer. In a preferred embodiment of the invention, the hole injection layer is a mixed film layer of a host organic material and a p-type dopant. For holes to be smoothly injected from the anode into the organic film layer, the HOMO energy level of the host organic material must possess certain characteristics with the p-type dopant to facilitate charge transfer states between the host and dopant materials, achieving ohmic contact between the hole injection layer and the anode, thereby achieving efficient hole injection from the electrode to the hole injection layer. This characteristic is summarized as follows: the difference between the HOMO energy level of the host material and the LUMO energy level of the p-type dopant is ≤0.4 eV. Therefore, for hole-type host materials with different HOMO energy levels, different p-type dopant materials need to be selected to match them in order to achieve ohmic contact at the interface and improve the hole injection effect.

[0078] Preferably, specific examples of the host organic material include: metalloporphyrins, oligothiophenes, aromatic amine organic materials, hexanitrile hexaazabenzanphenanthrene, quinacridone organic materials, perylene organic materials, anthraquinones, polyanilines, and polythiophene conductive polymers; but are not limited thereto. Preferably, the host organic material is an aromatic amine organic material.

[0079] Preferably, the p-type doped material is a charge-conducting compound selected from quinone derivatives or metal oxides, such as tungsten oxide and molybdenum oxide, but not limited thereto.

[0080] In a preferred embodiment of the present invention, the p-type doped material used is selected from any one of the following compounds P-1 to P-8:

[0081]

[0082] In one embodiment of the present invention, the ratio of the host organic material to the P-type doped material is 99:1-95:5, preferably 99:1-97:3, based on mass.

[0083] In a preferred embodiment of the present invention, the hole injection layer is a mixed film layer of aromatic amine compound and P-type doped material, wherein the aromatic amine compound is an aromatic amine compound of general formula (1).

[0084] The thickness of the hole injection layer of the present invention can be 5-20 nm, preferably 8-15 nm, but the thickness is not limited to this range.

[0085] Hole transport layer

[0086] In the organic electroluminescent device of the present invention, a hole transport layer may be disposed above a hole injection layer. The hole transport material is a suitable material with high hole mobility, capable of accepting holes from the anode or hole injection layer and transporting the holes to the light-emitting layer. Specific examples include, but are not limited to, aromatic amine organic materials, conductive polymers, and block copolymers having both conjugated and non-conjugated portions. In a preferred embodiment, the hole transport layer comprises the same aromatic amine organic compound as the hole injection layer.

[0087] The thickness of the hole transport layer of the present invention can be 80, 100 or 200 nm, preferably 100-150 nm, but the thickness is not limited to this range.

[0088] Light-emitting layer auxiliary layer

[0089] In the organic electroluminescent device of the present invention, an auxiliary light-emitting layer may be disposed between the hole transport layer and the light-emitting layer, and particularly in contact with the light-emitting layer. By disposing of the auxiliary light-emitting layer in contact with the light-emitting layer, hole transfer at the interface between the light-emitting layer and the hole transport layer can be precisely controlled. In one embodiment of the present invention, the material of the auxiliary light-emitting layer is selected from aromatic amine compounds of general formula (1). The thickness of the auxiliary light-emitting layer may be 5-20 nm, preferably 8-15 nm, but is not limited to this range.

[0090] Electronic transmission area

[0091] In the organic electroluminescent device of the present invention, the electron transport region is disposed between the light-emitting region and the cathode, and includes, but is not limited to, a hole blocking layer, an electron transport layer and an electron injection layer.

[0092] Electron injection layer

[0093] An electron injection layer may be disposed between the electron transport layer and the cathode. The electron injection layer material is typically preferably a material with a low work function, allowing electrons to be easily injected into the organic functional material layer. Preferably, the electron injection layer material is an N-type metal. As the electron injection layer material for the organic electroluminescent device of the present invention, electron injection layer materials known in the art for organic electroluminescent devices can be used, such as lithium; lithium salts, such as lithium 8-hydroxyquinoline, lithium fluoride, lithium carbonate, or lithium azide; or cesium salts, such as cesium fluoride, cesium carbonate, or cesium azide. The thickness of the electron injection layer of the present invention may be 0.1-5 nm, preferably 0.5-3 nm, and more preferably 0.8-1.5 nm, but the thickness is not limited to this range.

[0094] Electron transport layer

[0095] An electron transport layer may be disposed above the light-emitting film layer or (if present) a hole-blocking layer. The electron transport layer material is one that readily receives electrons from the cathode and transfers the received electrons to the light-emitting layer. A material with high electron mobility is preferred. As the electron transport layer of the organic electroluminescent device of the present invention, electron transport layer materials known in the prior art for organic electroluminescent devices can be used, such as metal complexes of hydroxyquinoline derivatives represented by Alq3, BAlq and LiQ, various rare earth metal complexes, triazole derivatives, triazine derivatives such as 2,4-bis(9,9-dimethyl-9H-fluoren-2-yl)-6-(naphth-2-yl)-1,3,5-triazine (CAS No.: 1459162-51-6), imidazole derivatives such as 2-(4-(9,10-bis(naphth-2-yl)anthracene-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole (CAS No.: 561064-11-7, commonly known as LG201), oxadiazole derivatives, etc.

[0096] In a preferred organic electroluminescent device of the present invention, the electron transport layer comprises a nitrogen heterocyclic compound of general formula (4):

[0097]

[0098] Ar5, Ar6, and Ar7 are independently selected from substituted or unsubstituted C6-C. 30 Aryl, substituted or unsubstituted C3-C containing one or more heteroatoms 30 One of the heterocyclic groups;

[0099] L3 represents C6-C with a single bond, substitution, or no substitution. 30 aryl, substituted or unsubstituted C3-C containing one or more heteroatoms 30 One of the heterocyclic groups; X1, X2, and X3 independently represent N or CH, and at least one of X1, X2, and X3 represents N;

[0100] The heteroatoms are selected from N, O, or S;

[0101] The substituents used for the substituent groups are one or more of the following: deuterium, phenyl, naphthyl, biphenyl, dibenzofuranyl, dibenzothiophenyl, pyridyl, or pyrimidinyl.

[0102] In a preferred embodiment, Ar5, Ar6, and Ar7 are independently represented as one of substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted dibenzothiophene, or substituted or unsubstituted quinolinyl.

[0103] The L3 is represented as a single bond, phenylene, biphenylene, or naphthylene;

[0104] The substituents used for the substituent groups are one or two of the following: deuterium, phenyl, naphthyl, biphenyl, dibenzofuranyl, dibenzothiophenyl, pyridyl, and pyrimidinyl.

[0105] In a preferred embodiment of the invention, the electron transport layer comprises any one of the following compounds:

[0106]

[0107]

[0108] In a more preferred embodiment of the invention, the electron transport layer comprises any one of the following compounds:

[0109]

[0110] In a preferred embodiment of the invention, in addition to the nitrogen heterocyclic compound of general formula (4), the electron transport layer also includes other compounds conventionally used for electron transport layers, such as Alq3, LiQ, preferably LiQ. In a more preferred embodiment of the invention, the electron transport layer consists of one of the compounds of general formula (4) and another of the compounds conventionally used for electron transport layers (preferably LiQ).

[0111] The hole injection and transport rates of the hole transport region containing the aromatic amine compounds of the present invention can be well matched with the electron injection and transport rates. Preferably, the hole injection and transport rates of the hole transport region containing the aromatic amine compounds of the present invention can be better matched with the electron injection and transport rates of the electron transport region containing the nitrogen heterocyclic compounds of general formula (4).

[0112] Therefore, in a particular embodiment of the present invention, using an electron transport region consisting of one or more nitrogen heterocyclic compounds of general formula (4) or composed thereof, in combination with a hole transport region consisting of an aromatic amine compound of the present invention, achieves relatively better technical results.

[0113] The thickness of the electron transport layer of the present invention can be 10-80 nm, preferably 20-60 nm, and more preferably 25-45 nm, but the thickness is not limited to this range.

[0114] Cover layer

[0115] To improve the light extraction efficiency of organic electroluminescent devices, a light extraction layer (CPL layer, also known as a capping layer) can be added to the cathode of the device. According to the principles of optical absorption and refraction, the CPL capping 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 or N4,N4'-diphenyl-N4,N4'-di(9-phenyl-3-carbazolyl)biphenyl-4,4'-diamine. The thickness of the CPL capping layer is typically 5-300 nm, preferably 20-100 nm, and more preferably 40-80 nm.

[0116] The organic electroluminescent device of the present invention may further 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.

[0117] The organic electroluminescent device according to an embodiment of the present invention is described below.

[0118] In the accompanying drawings, the thicknesses of layers, films, substrates, regions, etc., are enlarged for clarity. Throughout the specification, the same reference numerals denote the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as "on" another element, it may be directly on the other element or there may be intercalating elements. In contrast, when an element is referred to as "directly on" another element, there are no intercalating elements.

[0119] This invention also relates to a method for fabricating an organic electroluminescent device, comprising sequentially laminating an anode, a hole injection layer, a hole transport layer, a light-emitting auxiliary layer, an organic film layer, an electron transport layer, an electron injection layer, and a cathode, and optionally a capping layer, on a substrate. In this regard, 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 thereto. In this invention, vacuum evaporation is preferably used to form the various layers. Those skilled in the art can conventionally select the various process conditions in the vacuum evaporation method according to actual needs.

[0120] 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.

[0121] Preparation Examples

[0122] Example 1: Synthesis of Compound 2

[0123]

[0124] In a three-necked flask, under nitrogen protection, add 0.01 mol of raw material B-1, 0.012 mol of raw material A-1, and 150 ml of toluene, and stir to mix. Then add 5 × 10⁻⁶ ml of toluene. -5 mol Pd2(dba)3, 5×10 -5 0.03 mol of tri-tert-butylphosphine and 0.03 mol of sodium tert-butoxide were heated to 105 °C and refluxed for 20 hours. A TLC sample showed no remaining starting material B-1, indicating complete reaction. The mixture was allowed to cool naturally to room temperature, filtered, and the filtrate was rotary evaporated until no fraction remained. The filtrate was then passed through a neutral silica gel column to give compound 2. Elemental analysis of the structure (molecular formula C) is required. 52 H 35 NO): Theoretical values: C, 90.54; H, 5.11; N, 2.03; Measured values: C, 90.50; H, 5.13; N, 2.05. LC-MS: Measured value: 690.34 ([M+H]) + ); Precision quality: 689.27.

[0125] Example 2: Synthesis of raw material B-8

[0126]

[0127] In a three-necked flask, under nitrogen protection, add 0.01 mol of raw material C-1, 0.012 mol of raw material D-1, and 150 ml of toluene, and stir to mix. Then add 5 × 10⁻⁶ ml of toluene. -5 mol Pd2(dba)3, 5×10 -5 0.03 mol of tri-tert-butylphosphine and 0.03 mol of sodium tert-butoxide were heated to 105 °C and refluxed for 15 hours. A TLC sample was taken, showing no remaining starting material C-1, indicating complete reaction. The mixture was allowed to cool naturally to room temperature, filtered, and the filtrate was rotary evaporated until no fraction remained. The filtrate was then passed through a neutral silica gel column to obtain starting material B-8. Elemental analysis of the structure (molecular formula C) was performed. 34 H 25N): Theoretical values: C, 91.24; H, 5.63; N, 3.13; Measured values: C, 91.20; H, 5.65; N, 3.17. LC-MS: Measured value: 448.39 ([M+H]) + ); Precision quality: 447.20.

[0128] The following compounds were prepared using the same method as in Example 2, and the raw materials are shown in Table 1 below;

[0129] Table 1

[0130]

[0131] The following compounds were prepared using the same method as in Example 1, and the raw materials are shown in Table 2 below;

[0132] Table 2

[0133]

[0134]

[0135] Fabrication of organic electroluminescent devices

[0136] The molecular structural formulas of the materials involved in the following preparation process are shown below:

[0137]

[0138] Device Comparison Example 1

[0139] Organic electroluminescent devices are prepared according to the following steps:

[0140] like Figure 1As shown, substrate layer 1 is transparent glass. Anode layer 2 (Ag (100nm)) is washed sequentially with alkaline washing, pure water washing, drying, and then ultraviolet-ozone washing to remove organic residues from the surface of the anode layer. After the above washing, a hole injection layer 3 (HT-1 and P-1, 10nm thick) is deposited on anode layer 2 using a vacuum evaporation apparatus, with a mass ratio of HT-1 to P-1 of 97:3. Next, a hole transport layer 4 (117nm thick) of HT-1 is deposited. Subsequently, a hole transport layer 4 (EB-1, 10nm thick) is deposited as an auxiliary light-emitting layer 5. After the deposition of the auxiliary light-emitting layer materials, the light-emitting layer 6 of the OLED device is fabricated. Its structure includes BH-1 as the main material and BD-1 as the dopant material, with a doping ratio of 3% by weight, and a film thickness of 20nm. After the light-emitting layer 6, HB-1 is deposited to a thickness of 8nm as a hole blocking layer 7. On top of the hole-blocking layer 7, ET-1 and Liq are further deposited by vacuum evaporation, with an ET-1 to Liq mass ratio of 1:1. The vacuum-deposited film thickness of this material is 30 nm, and this layer serves as the electron transport layer 8. On the electron transport layer 8, a LiF layer with a thickness of 1 nm is formed by vacuum evaporation, and this layer serves as the electron injection layer 9. On the electron injection layer 9, a Mg:Ag electrode layer with a thickness of 16 nm is formed by vacuum evaporation, with a Mg to Ag mass ratio of 1:9, and this layer serves as the cathode layer 10. On the cathode layer 10, a 65 nm layer of CP-1 is vacuum-deposited as the CPL layer 11.

[0141] Device Comparison Example 2-11

[0142] The method was carried out according to the device comparison example 1, except that the organic materials in the auxiliary layers of the light-emitting layer were replaced with the organic materials shown in Table 3.

[0143] Device Examples 1-9

[0144] The method was carried out in accordance with the method of Comparative Example 1, except that the organic materials in the light-emitting auxiliary layer or electron transport layer were replaced with the organic materials shown in Table 3.

[0145] Table 3

[0146]

[0147]

[0148] Taking Example 1 as an example in the table above, "P-1:HT1=3:9710nm" in the second column indicates that the material used for the hole injection layer is compound HT1 and P-type doped material P-1, 3:97 refers to the weight ratio of P-type doped material P-1 to compound HT1 of 3:97, and 10nm represents the thickness of the layer; "210nm" in the fourth column indicates that the material used is compound 2, and the thickness of the layer is 10nm. The meanings in the other tables can be deduced similarly.

[0149] After fabricating the OLED light-emitting device as described above, the cathode and anode were connected using a known driving circuit, and various performance parameters of the device were measured. The performance measurement results of the devices in Examples 1-11 and Comparative Examples 1-9 are shown in Table 4.

[0150] Table 4

[0151]

[0152] Note: LT95 refers to a brightness of 50mA / cm². 2 Under certain conditions, the time it takes for the device's brightness to decay to 95% of its original brightness;

[0153] Voltage, current efficiency, and color coordinates were measured using an IVL (current-voltage-luminance) testing system (Suzhou Fushida Scientific Instruments Co., Ltd.); the current density was 10 mA / cm². 2 ;

[0154] The lifetime testing system is the EAS-62C OLED lifetime testing system from Japan Systems Research Co., Ltd.

[0155] As can be seen from the results of Comparative Examples 1-11 and Device Examples 1-9 in Table 4, using the aromatic amine compounds of the present invention as the light-emitting auxiliary layer material effectively improves the device efficiency and lifetime due to their high carrier transport rate and exciton blocking ability. In particular, the device efficiency is significantly improved unexpectedly while maintaining a certain lifetime advantage.

Claims

1. An aromatic amine compound, characterized in that, The structure of the compound is shown in general formula (1): In general formula (1), R is selected from the structure shown in formula (A), formula (B), formula (C) or formula (D); R1 represents phenyl, naphthyl, biphenyl, dibenzofuranyl or dibenzothiophene, and when R1 represents dibenzofuranyl or dibenzothiophene, R is not selected from formula (A); The L represents phenylene, biphenylene, or naphthylene.

2. The aromatic amine compound according to claim 1, characterized in that, The structure of the compound is shown in general formula (1-1): R1 represents phenyl, naphthyl, biphenyl, phenyl-substituted naphthyl, dibenzofuranyl, or dibenzothiopheneyl; The L represents phenylene, biphenylene, or naphthylene.

3. The aromatic amine compound according to claim 1, characterized in that, The structure of the compound is shown in general formula (1-2); R1 represents phenyl, naphthyl, biphenyl, or phenyl-substituted naphthyl; The L represents phenylene, biphenylene, or naphthylene.

4. The aromatic amine compound according to claim 1, characterized in that, The structure of the compound is shown in general formula (1-3); R1 represents phenyl, naphthyl, biphenyl, phenyl-substituted naphthyl, dibenzofuranyl, or dibenzothiopheneyl; The L represents phenylene, biphenylene, or naphthylene.

5. The aromatic amine compound according to claim 1, characterized in that, The structure of the compound is shown in general formula (1-4): The L represents phenylene, biphenylene, or naphthylene.

6. The aromatic amine compound according to claim 1, characterized in that, The structure of the compound is shown in general formula (1-5); The L represents a direct bond, phenylene, or naphthylene.

7. The aromatic amine 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, in sequence, an anode, a hole transport region, a light-emitting region, an electron transport region, and a cathode, characterized in that, The hole transport region comprises any one of the aromatic amine compounds according to claims 1-7.

9. The organic electroluminescent device according to claim 8, characterized in that, The hole transport region includes a hole injection layer, a hole transport layer, and a light-emitting auxiliary layer, wherein the light-emitting auxiliary layer comprises an aromatic amine compound as described in any one of claims 1-7.

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

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