An organic electroluminescence compound, a preparation method therefor, and use thereof

Abstract

The application discloses an organic electroluminescent compound, a preparation method and application thereof, and relates to the technical field of organic photoelectric materials.The compound provided by the application changes the position of a substituent group, increases a dihedral angle of the compound, and makes the molecular configuration more twisted.In this way, on the one hand, according to the two twisted planes, the crystallinity can be reduced due to the reduction of intermolecular interaction, the molecular aggregation and accumulation are reduced, the plugging phenomenon in evaporation is reduced, meanwhile, the intermolecular interaction is weakened, the evaporation temperature of the organic electroluminescent compound can be reduced, and the change of the compound structure caused by long-time heating can be avoided.On the other hand, the carrier transport traps are not easily formed due to the reduction of the molecular aggregation, the migration of holes is facilitated, the OLED device obtained is further improved in the service life and luminous efficiency, and the requirement of mass production of organic electroluminescent displays is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic photoelectric materials, in particular to an organic electroluminescent compound, a preparation method and application thereof. BACKGROUND

[0002] An organic electroluminescent display (OLED) is an active light-emitting display device, which has the characteristics of self-emission, bright and vivid color, thin thickness, light weight, fast response speed, wide viewing angle, low driving voltage, resistance to harsh natural conditions, and can be made into a flexible panel, etc. At present, small and medium-sized OLED display screens have been widely used in high-end smart phones. It is a common demand in the field of OLED to obtain the best luminous efficiency of the device under low working voltage conditions.

[0003] An organic electroluminescent device generally has the following structure: an anode, a cathode, and an organic material layer between the two. In order to improve the efficiency and stability of the organic EL element, the organic material layer is composed of different functional layers, such as a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting auxiliary layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer (ETL), and an electron injection layer (EIL).

[0004] The evaporation of organic functional layer materials needs to be carried out at high temperature, but the phenomenon of degradation of organic functional layer materials often occurs at high temperature. One of the reasons for the degradation of organic functional layer materials is that the increase of evaporation temperature caused by material structure leads to changes in the chemical structure of the material due to long-term heating. In addition, the morphology of the organic functional layer material in the device formed by evaporation is an amorphous disordered film, and the morphology of the thin film formed by evaporation affects the evaporation temperature and the service life and luminous efficiency of the OLED device. Therefore, it is particularly important to develop organic functional materials with higher performance to meet the requirements of panel manufacturing enterprises in mass production of organic electroluminescent displays.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide an organic electroluminescent compound and a preparation method thereof, which aims to reduce the clogging problem of the material in the evaporation process, and at the same time, reduce the evaporation temperature of the organic electroluminescent compound, and avoid the problem of changes in the structure of the compound caused by long-term heating.

[0007] Another purpose of the present application is to provide an organic material layer and an organic electroluminescent device, which aims to improve the service life and luminous efficiency of the OLED device.

[0008] The present application is realized as follows:

[0009] In a first aspect, the present application provides an organic electroluminescent compound, the structure general formula of which is shown in Formula I:

[0010]

[0011] In formula I, n is an integer selected from 1 to 4, and each R is independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl and phenyl;

[0012] L is selected from any one of a single bond, phenyl, biphenyl and naphthyl;

[0013] Each of Ar1 and Ar2 is independently selected from any one of dimethylfluorenyl, biphenyl, dibenzofuranyl, diphenylfluorenyl, dibenzothiophenyl, naphthyl, carbazolyl and N-phenylcarbazolyl.

[0014] In a second aspect, the present application provides a preparation method of the organic electroluminescent compound in the foregoing embodiments, which comprises the following steps: reacting a reactant A-I with a reactant B-I to obtain an intermediate C-I, reacting the intermediate C-I under acidic conditions to obtain an intermediate D-I, and finally preparing the target compound by substitution reaction of halogen in the intermediate D-I, and the reaction route is as follows:

[0015]

[0016] In a third aspect, the present application provides an organic material layer prepared from the organic electroluminescent compound in the foregoing embodiments.

[0017] In a fourth aspect, the present application provides an organic electroluminescent device comprising an anode, a cathode and the organic material layer in the foregoing embodiments, wherein the organic material layer is located between the anode and the cathode.

[0018] The present application has the following beneficial effects: the compound provided by the present application changes the position of the substituent group, increases the dihedral angle of the compound, and makes the molecular configuration more twisted, thereby reducing the molecular aggregation and accumulation, improving the migration of holes, and further avoiding the formation of carrier transport traps. In this way, the crystallinity can be reduced due to the reduction of the intermolecular interaction, the molecular aggregation and accumulation are reduced, the plugging phenomenon in evaporation is reduced, at the same time, the intermolecular interaction is weakened, the evaporation temperature of the material compound can be reduced, and the change of the chemical structure of the material caused by long-time heating is avoided. On the other hand, due to the reduction of the molecular aggregation, the carrier transport traps are not easily formed, which is beneficial to the migration of holes, and the OLED device obtained further improves the service life and luminous efficiency, and meets the requirements of mass production of organic electroluminescent displays. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be considered as limiting the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0020] Figure 1 NMR of compound 2;

[0021] Figure 2 NMR of compound 32;

[0022] Figure 3 NMR of compound 80;

[0023] Figure 4 Test results of NPT method simulation of thin film disordered packing density in molecular dynamics. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described as follows. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.

[0025] In the present application, the term "substituted" means that the hydrogen atom bonded to the carbon atom of the compound is changed into another substituent, and the position of substitution is not limited as long as the position is the position of hydrogen atom to be substituted (i.e. the position of substituent that can be substituted), and when two or more substituents are substituted, the two or more substituents can be the same or different from each other.

[0026] In the present specification, the term "substituted or unsubstituted" means substituted with one, two or more substituents selected from the following. For example, "substituents connected to two or more substituents" can include biphenyl. In other words, biphenyl can be an aryl group, or can be interpreted as substituents to which two phenyl groups are connected.

[0027] The embodiments of the present application provide an organic electroluminescent compound, the structure general formula of which is shown as formula I:

[0028]

[0029] In Formula I, n is an integer selected from 1 to 4, each R is independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl and phenyl; L is selected from any one of a single bond, phenyl, biphenyl and naphthyl; each of Ar1 and Ar2 is independently selected from any one of dimethylfluorenyl, biphenyl, dibenzofuranyl, diphenylfluorenyl, dibenzothiophenyl, naphthyl, carbazolyl and N-phenylcarbazolyl.

[0030] Specifically, n represents the number of R groups, which can be 1, 2, 3 or 4, each R is independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl and phenyl, which can be the same or different. For example, n can be 2, one R group is methyl and the other R group is ethyl.

[0031] Specifically, each of Ar1 and Ar2 is a group connected to N, which is independently selected from the above groups, and can be the same or different.

[0032] When n is 1, there are four possible positions of the substituent group, as shown in Formula I-1 to Formula I-4:

[0033]

[0034] wherein each of R1 to R4 is independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl and phenyl, and R1, R2, R3 and R4 can be the same or different.

[0035] In some embodiments, n is 2, and there are six possible positions of the two substituent groups, as shown in Formula I-5 to Formula I-10:

[0036]

[0037] wherein each of R1 to R4 is independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl and phenyl, and R1, R2, R3 and R4 can be the same or different.

[0038] In some embodiments, the structure of the organic electroluminescent compound is selected from at least one of compounds 1-92:

[0039]

[0040]

[0041]

[0042]

[0043] It should be noted that the inventors found that when compounds 1-92 are used to prepare an organic material layer, they are all conducive to reducing molecular aggregation and accumulation, reducing the plugging problem in evaporation, at the same time, the interaction between molecules is weakened, which can reduce the evaporation temperature of the compound, avoid the change of the chemical structure of the material caused by long time heating, and also can improve the service life, luminous efficiency and driving voltage of the OLED device to a certain extent.

[0044] In addition, compounds 1-92 are only preferred embodiments given, and compounds satisfying formula I are within the protection scope of the present application.

[0045] The embodiment of the present application also provides a preparation method of an organic electroluminescent compound, which is used for preparing the compound of formula I, and specifically comprises the following steps:

[0046] S1, preparing intermediate D-I

[0047] The intermediate C-I is obtained by reacting the reactant A-I and the reactant B-I, and then the intermediate D-I is obtained by reacting the intermediate C-I under acidic conditions, and the reaction route is as follows:

[0048]

[0049] Specifically, the route for preparing the intermediate D-I from the reactant A-I and the reactant B-I is as follows:

[0050]

[0051] By further controlling the solvents, basic reagents, acidic reagents and the like used in the reaction process, the yield of the product can be further improved.

[0052] In actual operation, the process for preparing the intermediate D-I from the reactant A-I and the reactant B-I includes: after the reactant B-I is dissolved, the reactant B-I is reacted with n-BuLi at-75 to-80℃ for 1-3h, then the mixed solution formed after the reactant A-I is dissolved is added dropwise into the reaction system, after the dropwise addition is completed, the reaction is terminated by warming, and the organic phase is collected and separated to obtain the intermediate C-I; the intermediate C-I is dissolved in HOAC, H2SO4 is added dropwise at 90-110℃, the reaction is carried out for 0.5-2h, after the reaction is terminated, the organic phase is collected and separated to obtain the intermediate D-I.

[0053] Specifically, the two halogen elements on the reactant B-I are used for substitution to introduce the target group, and the present embodiment mainly selects suitable raw materials and a reaction route, and the specific reaction conditions are conventional conditions of this type of reaction, such as solvents, catalysts, temperature and time, which can not be limited to the above range, as long as the preparation method of the synthesis route provided in the present application is within the protection scope of the present application.

[0054] S2, target compound preparation

[0055] The target compound is prepared by substitution reaction from halogen in intermediate D-I, and the raw materials are different when L is not a single bond, and the specific process is as follows:

[0056] When L is a single bond, the reaction route for preparing the target compound from intermediate D-I is as follows:

[0057]

[0058] In actual operation, the process of preparing the target compound from intermediate D-I includes: after intermediate D-I and reactant E-I are dissolved, reaction is carried out in the presence of Pd2(dba)3, P(t-Bu)3 and t-BuONa, the reaction temperature is controlled to be 105-115℃, and the reaction time is 6-10h; after the reaction is completed, filtration is carried out, the filtrate is cooled, and the solvent is removed by rotary evaporation, the obtained solid is dried and eluted, the eluted filtrate is rotary evaporated, and the rotary evaporated solid is dried to obtain the compound of general formula I.

[0059] Specifically, filtration after reaction can be carried out by suction filtration, and hot filtration is appropriate. The purpose of filtration is to remove salt and catalyst.

[0060] It should be noted that the solvents, catalysts and other raw materials used in the synthesis process can be common reagents that meet the overall synthesis route, and are not limited to the above reagents. The reaction temperature and time can be within the above range, for example, the reaction temperature can be 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, etc., and can also be any value between the above adjacent temperature values.

[0061] When L is not a single bond, the reaction route for preparing the target compound from intermediate D-I is as follows:

[0062]

[0063] In actual operation, after intermediate D-I and reactant E-I are dissolved, reaction is carried out in the presence of Pd(PPh)4 and potassium carbonate, the reaction temperature is controlled to be 110-120℃, and the reaction time is 8-12h; after the reaction is completed, filtration is carried out, the filtrate is cooled, and the solvent is removed by rotary evaporation, the obtained solid is dried and eluted, the eluted filtrate is rotary evaporated to remove the solvent, and the rotary evaporated solid is dried to obtain the compound of general formula I.

[0064] Specifically, the filtration after the reaction can be performed by suction filtration, and hot filtration is preferable. The purpose of the filtration is to remove the salt and the catalyst.

[0065] The present application also provides an organic material layer prepared from the above-mentioned organic electroluminescent compound, and the above-mentioned compound can be used to prepare a light-emitting layer.

[0066] The present application also provides an organic electroluminescent device comprising an anode, a cathode, and an organic material layer, wherein the organic material layer is located between the anode and the cathode, and the specific types of the anode and the cathode are not limited.

[0067] Specifically, the organic electroluminescent device can have a structure comprising a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting auxiliary layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, a cap layer, and the like as the organic material layer. However, the structure of the organic light-emitting element is not limited thereto, and can comprise a smaller or larger number of organic layers.

[0068] Specifically, as for the compound represented by the above-mentioned formula I, in the production of the organic light-emitting element, a vacuum evaporation method can be used, or a solution coating method can be used to form the organic material layer. The solution coating method refers to a spin coating method, a dip coating method, a blade coating method, an inkjet printing method, a screen printing method, a spray method, a roll coating method, and the like, but is not limited thereto.

[0069] The organic light-emitting element of the present application can be a top emission type, a bottom emission type, or a bidirectional emission type, depending on the materials used. The device described in the present application can be used in an organic light-emitting device, an organic solar cell, electronic paper, an organic photoreceptor, or an organic thin film transistor.

[0070] Specifically, as the anode material (i.e., the anode), a material with a large work function is generally preferred in order to enable smooth injection of holes into the organic material layer. As the anode material that can be used in the present application, there can be mentioned metals such as vanadium, chromium, copper, zinc, gold, and alloys thereof; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), and the like; combinations of a metal and an oxide such as ZnO:Al or SnO2:Sb; conductive polymers such as polypyrrole and polyaniline; and the like.

[0071] Specifically, the hole injection layer is preferably a p-doped hole injection layer, which means a hole injection layer doped with a p-dopant. The p-dopant is a material that imparts p-type semiconductor properties. The p-type semiconductor properties mean the properties of injecting or transporting holes at the HOMO level, i.e., the properties of a material having a high hole conductivity. The p-doped p-dopant can be exemplified by the following compounds, but is not limited thereto.

[0072]

[0073] Specifically, the hole transport layer is placed between the anode and the light-emitting layer, and it can be used to facilitate hole injection and / or hole transport, or to prevent electron overflow.

[0074] The hole transport material can be selected from arylamine derivatives, conductive polymers, and block copolymers having both conjugated and non-conjugated portions, etc. Specifically, the hole transport layer material is selected from the following compounds, but is not limited thereto.

[0075]

[0076] In some embodiments, the organic material layer comprises a light-emitting auxiliary layer, and the light-emitting auxiliary layer is prepared from a compound represented by Formula I of the present application.

[0077] The light-emitting substance of the light-emitting layer is a substance that can receive holes and electrons from the hole transport layer and the electron transport layer, respectively, and combine them to emit light in the visible region. Preferably, the light-emitting substance has a high quantum efficiency for fluorescence or phosphorescence.

[0078] The light-emitting layer can comprise a host material and a dopant material.

[0079] The mass ratio of the host material to the dopant material is 90-99.5:0.5-10.

[0080] The host material can be an aromatic condensed ring derivative or a heterocyclic compound, etc. Specifically, as the aromatic condensed ring derivative, there are anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentacene derivatives, phenanthrene compounds, fluoranthene compounds, etc., and as the heterocyclic compound, there are carbazole derivatives, diphenylfuran derivatives, pyrimidine derivatives, etc. Specifically, the host material of the present application is selected from the following compounds, but is not limited thereto.

[0081]

[0082]

[0083] The dopant material of the present application includes fluorescent dopants and phosphorescent dopants. It can be selected from aromatic amine derivatives, styrylamine compounds, boron complexes, fluoranthene compounds, metal complexes, etc. Specifically, the dopant material of the present application is selected from the following compounds, but is not limited thereto.

[0084]

[0085]

[0086] Specifically, the electron transport region can include at least one of an electron buffer layer, a hole blocking layer, an electron transport layer, and an electron injection layer, and preferably at least one of the electron transport layer and the electron injection layer. The electron transport region is a layer capable of improving a problem of luminance deterioration due to a change in current characteristics in the device when the device is exposed to high temperature during a process of manufacturing a panel, and it can control charge flow characteristics.

[0087] The material of the electron transport layer (hole blocking layer) is a derivative of oxazole, imidazole, thiazole, triazine, etc., a metal chelate, a quinoline derivative, an oxinyl derivative, a diazanthracene derivative, a phenanthroline derivative, a silicon-containing heterocyclic compound, a perfluorinated oligomer, etc., and specifically, the electron transport layer material is selected from the following compounds, but is not limited thereto.

[0088]

[0089]

[0090] Specifically, the electron injection layer material is fluorenone, anthraquinone dimethane, diphenylquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylene tetracarboxylic acid, fluorenylidene methane, anthrone, etc., and derivatives, metal complexes, and nitrogen-containing 5-membered ring derivatives thereof, but is not limited thereto.

[0091] Specifically, the cathode material is preferably a material having a small work function in order to easily inject electrons into the organic layer. As a specific example of the cathode material, there are metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloys thereof: LiF / Al or LiO2 / Al, a multi-layered structure material such as Mg / Ag, etc.

[0092] There is no particular limitation on the materials of other layers in the OLED device except that the light emitting auxiliary layer disclosed herein contains Formula I. Existing hole injection materials, hole transport materials, dopant materials, hole blocking layer materials, electron transport layer materials, and electron injection materials can be used.

[0093] The features and properties of the present application are further described in detail below in connection with examples.

[0094] Example 1

[0095] This example provides a method for preparing compound 2, as follows:

[0096]

[0097] Step 1:

[0098] Under N2protection, the reactant B-2 (55 mmol) was dissolved in THF, cooled to -78 °C, and n-BuLi (55 mmol) was added dropwise. After stirring for 2 h at -78 °C, the reactant A-2 (50 mmol) was dissolved in THF and added dropwise to the reaction system. After the addition was completed, the temperature was raised to room temperature and stirring was performed. Distilled water was added to terminate the reaction, and the organic phase was collected by liquid separation and dried by adding anhydrous magnesium sulfate. The solvent was removed by a rotary evaporator, and the solid was dried to obtain the intermediate C-2 (16.56 g, yield: 86%, Mw: 385.10).

[0099] Step 2:

[0100] Under N2protection, the intermediate C-2 (40 mmol) was dissolved in HOAC (200 mL), and H2SO4 (4 mL) was added dropwise while the temperature was raised to 100 °C. After stirring for 1 h, the temperature was cooled to room temperature, and saturated sodium bicarbonate solution was added to terminate the reaction. The liquid was separated, and the aqueous phase was extracted with dichloromethane. The organic phase was collected, dried by adding anhydrous magnesium sulfate, and the solvent was removed by a rotary evaporator. The solid was dried to obtain the intermediate D-2 (13.07 g, yield: 89%, Mw: 367.15).

[0101] Step 3

[0102] Under N2protection, the intermediate D-2 (34 mmol) and the reactant E-2 (40.8 mmol) were dissolved in toluene, and Pd2(dba)3 (0.34 mmol), P(t-Bu)3 (1.7 mmol), and t-BuONa (68 mmol) were added. After the addition, the temperature was raised to 105 °C, and the reaction was performed for 8 h. After hot filtration with diatomite to remove the salt and catalyst, the filtrate was cooled to room temperature, and the solvent was removed by a rotary evaporator. The obtained solid was dried, passed through a silica gel funnel, and eluted with dichloromethane: petroleum ether (volume ratio 1:1-4) as the eluent. The filtrate was removed by a rotary evaporator, and the obtained solid was dried to obtain compound 2 (20.47 g, yield: 87%).

[0103] The obtained compound 2 was characterized as shown in Figure 1

[0104] HPLC purity: >99.7%.

[0105] Mass spectrometry test: the theoretical value was 691.92; the test value was 692.19.

[0106] Elemental analysis:

[0107] Theoretical value: C, 92.00; H, 5.97; N, 2.02;

[0108] ​Test value: C, 91.74; H, 6.22; N, 2.13.

[0109] Example 2

[0110] This example provides a method for preparing compound 26, as follows:

[0111]

[0112] Step 1:

[0113] Under N2protection, the reactant B-26 (55 mmol) was added to a reaction vessel, dissolved in THF, and cooled to -78°C. n-BuLi (55 mmol) was added dropwise, and stirred at -78°C for 2 h. The reactant A-26 (50 mmol) was dissolved in tetrahydrofuran, and added dropwise to the reaction system. After the dropwise addition was completed, the temperature was raised to room temperature and stirred. Distilled water was added to terminate the reaction, and the organic phase was collected by liquid separation. Anhydrous magnesium sulfate was added for drying. The solvent was removed by a rotary evaporator, and the solid was dried to obtain the intermediate C-26 (18.15 g, yield: 85%, Mw: 427.18).

[0114] Step 2:

[0115] Under N2protection, the intermediate C-26 (40 mmol) was added to a reaction vessel, dissolved in HOAC (200 mL), and heated to 100°C. H2SO4 (4 mL) was added dropwise, and stirred for 1 h. The temperature was cooled to room temperature, and saturated sodium bicarbonate solution was added to terminate the reaction. The liquid was separated, and the aqueous phase was extracted with dichloromethane. The organic phase was collected, anhydrous magnesium sulfate was added for drying, and the solvent was removed by a rotary evaporator. The solid was dried to obtain the intermediate D-26 (14.89 g, yield: 91%, Mw: 409.16).

[0116] Step 3

[0117] Under N2protection, the intermediate D-26 (34 mmol) and the reactant E-26 (40.8 mmol) were added to a reaction vessel after being dissolved in toluene, and Pd2(dba)3 (0.34 mmol), P(t-Bu)3 (1.7 mmol), and t-BuONa (68 mmol) were added. After the addition, the temperature was raised to 105°C, and reacted for 8 h. Silica was used to hot-filtrate to remove the salt and catalyst. After the filtrate was cooled to room temperature, the solvent was removed by a rotary evaporator. The obtained solid was dried, passed through a silica gel funnel, and eluted with dichloromethane: petroleum ether (volume ratio 1:1-4) as the eluent. The filtrate was removed by a rotary evaporator, and the obtained solid was dried to obtain compound 26 (20.53 g, yield: 87%).

[0118] The obtained compound 26 was characterized as follows:

[0119] HPLC purity: >99.7%.

[0120] Mass test: Theoretical value is 693.93; test value is 694.15.

[0121] Elemental analysis:

[0122] Theoretical value: C, 91.74; H, 6.25; N, 2.02;

[0123] Test value: C, 91.56; H, 6.44; N, 2.10.

[0124] Example 3

[0125] This example provides a method for preparing compound 32, as follows:

[0126]

[0127] Step 1:

[0128] Under N2protection, the reactant B-32 (55 mmol) was added to a reaction vessel, dissolved in THF, cooled to -78°C, and n-BuLi (55 mmol) was added dropwise. After stirring at -78°C for 2 h, the reactant A-32 (50 mmol) was dissolved in tetrahydrofuran and added dropwise to the reaction system. After the dropwise addition was completed, the temperature was raised to room temperature and stirring was performed. Distilled water was added to terminate the reaction, the organic phase was collected by liquid separation, and anhydrous magnesium sulfate was added for drying. The solvent was removed by a rotary evaporator, and the solid was dried to obtain the intermediate C-32 (18.55 g, yield: 83%, Mw: 447.12).

[0129] Step 2:

[0130] Under N2protection, the intermediate C-32 (40 mmol) was added to a reaction vessel, dissolved in HOAC (200 mL), and heated to 100°C. H2SO4 (4 mL) was added dropwise, and the reaction was stirred for 1 h. After cooling to room temperature, saturated sodium bicarbonate solution was added to terminate the reaction. The liquid was separated, the aqueous phase was extracted with dichloromethane, the organic phase was collected, anhydrous magnesium sulfate was added for drying, the solvent was removed by a rotary evaporator, and the solid was dried to obtain the intermediate D-32 (15.45 g, yield: 90%, Mw: 429.10).

[0131] Step 3

[0132] To a reaction vessel was added intermediate D-32 (34 mmol) and reactant E-32 (40.8 mmol) dissolved in toluene under N2protection, followed by the addition of Pd2(dba)3(0.34 mmol), P(t-Bu)3(1.7 mmol), t-BuONa (68 mmol). After addition, the temperature was raised to 105 °C and the reaction was allowed to proceed for 8 h. The reaction mixture was filtered hot using celite to remove salts and catalyst, and the filtrate was allowed to cool to room temperature. The solvent was removed using a rotary evaporator, and the resulting solid was dried and passed through a silica gel funnel using dichloromethane: petroleum ether (1:1-4) as eluent. The filtrate was removed using a rotary evaporator, and the resulting solid was dried to obtain compound 32 (22.72 g, yield: 87%).

[0133] The obtained compound 32 was characterized as shown in Figure 2

[0134] HPLC purity: >99.8%.

[0135] Mass spectrometry test: the theoretical value was 767.97; the test value was 768.22.

[0136] Elemental analysis:

[0137] Theoretical value: C, 90.71; H, 5.38; N, 1.82; O, 2.08;

[0138] Test value: C, 90.46; H, 5.61; N, 1.90; O, 2.15.

[0139] Example 4

[0140] This example provides a method for preparing compound 33, as follows:

[0141]

[0142] Step 1:

[0143] To a reaction vessel was added reactant B-33 (55 mmol) dissolved in THF under N2protection, and the temperature was lowered to -78 °C. n-BuLi (55 mmol) was added dropwise, and the reaction was stirred at -78 °C for 2 h. Reactant A-33 (50 mmol) dissolved in tetrahydrofuran was added dropwise to the reaction system, and the temperature was raised to room temperature after the addition was complete. Distilled water was added to terminate the reaction, and the organic phase was collected by liquid separation and dried by the addition of anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator, and the solid was dried to obtain intermediate C-33 (16.36 g, yield: 82%, Mw: 399.11).

[0144] Step 2:

[0145] ​Under N2protection, intermediate C-33 (40 mmol) was dissolved in HOAC (200 mL) in a reaction vessel, heated to 100 °C, H2SO4(4 mL) was added dropwise, the reaction was stirred for 1 h, cooled to room temperature, saturated sodium bicarbonate solution was added to terminate the reaction, the solution was separated, the aqueous phase was extracted with dichloromethane, the organic phase was collected, dried with anhydrous magnesium sulfate, the solvent was removed by a rotary evaporator, and intermediate D-33 (13.11 g, yield: 86%, Mw: 381.16) was obtained after drying the solid.

[0146] Step 3

[0147] Under N2protection, intermediate D-33 (34 mmol) and reactant E-33 (40.8 mmol) were dissolved in toluene in a reaction vessel, followed by the addition of Pd2(dba)3(0.34 mmol), P(t-Bu)3(1.7 mmol), t-BuONa (68 mmol). After addition, it was heated to 105 °C and reacted for 8 h. After hot suction filtration with celite, the salt and catalyst were removed, and the filtrate was cooled to room temperature, and the solvent was removed using a rotary evaporator. The obtained solid was dried and passed through a silica gel funnel with dichloromethane: petroleum ether (1:1-4) as eluent. The filtrate was removed using a rotary evaporator, and the obtained solid was dried to obtain compound 33 (21.13 g, yield: 88%).

[0148] The obtained compound 33 was characterized as follows:

[0149] HPLC purity: >99.8%.

[0150] Mass spectrometry test: the theoretical value was 705.95; the test value was 706.27.

[0151] Elemental analysis:

[0152] Theoretical value: C, 91.88; H, 6.14; N, 1.98;

[0153] Test value: C, 91.60; H, 6.40; N, 2.10

[0154] Example 5

[0155] This example provides a method for preparing compound 80, as follows:

[0156]

[0157] Step 1:

[0158] Under N2protection, the reactant B-80 (55 mmol) was dissolved in THF, cooled to -78 °C, and n-BuLi (55 mmol) was added dropwise. After 2 h of stirring at -78 °C, the reactant A-80 (50 mmol) was dissolved in THF and added dropwise to the reaction system. After the addition was completed, the temperature was raised to room temperature and stirred. Distilled water was added to terminate the reaction, and the organic phase was collected by liquid separation and dried with anhydrous magnesium sulfate. The solvent was removed by a rotary evaporator, and the solid was dried to obtain the intermediate C-80 (17.57 g, yield: 87%, Mw: 385.12).

[0159] Step 2:

[0160] Under N2protection, the intermediate C-80 (40 mmol) was dissolved in HOAC (200 mL), and H2SO4 (4 mL) was added dropwise while the temperature was raised to 100 °C. After 1 h of stirring, the reaction was terminated by adding saturated sodium bicarbonate solution, and the liquid was separated. The aqueous phase was extracted with dichloromethane, and the organic phase was collected and dried with anhydrous magnesium sulfate. The solvent was removed by a rotary evaporator, and the solid was dried to obtain the intermediate D-80 (13.88 g, yield: 88%, Mw: 367.13).

[0161] Step 3

[0162] Under N2protection, the intermediate D-80 (34 mmol) and the reactant E-80 (40.8 mmol) were dissolved in a mixed solvent of toluene, ethanol, and water (V 甲苯 :V 乙醇 :V 水 = 300 mL:150 mL:150 mL), and then tetrakis(triphenylphosphine)palladium (Pd(PPh)4) (0.34 mmol) and potassium carbonate (K2CO3) (74.8 mmol) were added. After the addition, the temperature was raised to 110 °C, and the reaction was carried out for 12 h. The salt and catalyst were removed by hot suction filtration using diatomite, and the filtrate was cooled to room temperature. The solvent was removed using a rotary evaporator, and the obtained solid was dried and then passed through a silica gel funnel using dichloromethane: petroleum ether (1:1-4) as the eluent. The filtrate was removed using a rotary evaporator, and the obtained solid was dried to obtain compound 80 (23.63 g, yield: 86%).

[0163] The obtained compound 80 was characterized as shown in Figure 3

[0164] HPLC purity: >99.7%.

[0165] Mass spectrometry test: the theoretical value was 808.08; the test value was 808.29.

[0166] Elemental analysis: ​

[0167] Theoretical value: C, 92.15; H, 6.11; N, 1.73

[0168] Test value: C, 91.83; H, 6.42; N, 1.87

[0169] Examples 6-34

[0170] The synthesis of compounds 3, 5, 6, 9, 10, 11, 12, 13, 14, 16, 18, 20, 23, 29, 31, 36, 39, 45, 47, 49, 53, 57, 64, 67, 72, 76, 77, 84, 88 was completed according to the synthesis method of Examples 1-5.

[0171] Table 1: Mass spectrum, molecular formula as follows.

[0172]

[0173]

[0174] It should be noted that other compounds in the present application can be obtained according to the synthesis method of the above-mentioned examples, so they are not listed one by one here.

[0175] Application Example 1 - Preparation of green organic electroluminescent device, comprising the following steps:

[0176] (1) ITO anode: the ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150 nm is cleaned in distilled water for 2 times, ultrasonic washing for 30 min, and then repeatedly cleaned with distilled water for 2 times, ultrasonic washing for 10 min. After washing, it is transferred to the spin dryer for spin-drying, and finally baked in a vacuum oven at 220°C for 2 hours. After baking, it is cooled and ready for use. The substrate is used as an anode, and a device process is carried out by using an evaporation machine to evaporate other functional layers on it.

[0177] (2) HIL (hole injection layer): the hole injection layer materials HT1-7 and P-9 are vacuum evaporated at an evaporation rate of The chemical formula of the HT1-7 and P-9 is shown below. The evaporation rate ratio of the HT1-7 and P-9 is 97:3, and the thickness is 10 nm.

[0178] (3) HTL (hole transport layer): the HT1-7 is vacuum evaporated on the hole injection layer as a hole transport layer at an evaporation rate of The thickness of the hole transport layer is 120 nm.

[0179] (4) Light-emitting auxiliary layer: the compound 2 provided in the above examples is vacuum evaporated on the hole transport layer as a light-emitting auxiliary layer at an evaporation rate of The thickness of the light-emitting auxiliary layer is 45 nm.

[0180] (5) EML (Emission Layer): Then, the host material (Host-22 and Host-23) and the dopant material (Dopant-17) with a thickness of 400 nm were vacuum evaporated at an evaporation rate of 0.5 A / A and 0.5 A / A, respectively, as an emission layer on the above-mentioned light-emitting auxiliary layer, wherein Host-22 and Host-23 were co-evaporated as a dual-host material with the dopant material, and the ratio of Host-22 and Host-23 was 50:50, and the chemical formulas of Host-22 and Host-23 and Dopant are shown below. The evaporation rate ratio of the host material and Dopant was 88:12.

[0181] (6) HBL (Hole Blocking Layer): The hole blocking layer ET-12 with a thickness of 5.0 nm was vacuum evaporated at an evaporation rate of 0.5 A / A.

[0182] (7) ETL (Electron Transport Layer): The ET-4 and Liq with a thickness of 30 nm were vacuum evaporated at an evaporation rate of 0.5 A / A and 0.5 A / A, respectively, as an electron transport layer. The evaporation rate ratio of ET-4 and Liq was 50:50.

[0183] (8) EIL (Electron Injection Layer): The Yb film layer with a thickness of 1.0 nm was evaporated at an evaporation rate of 0.5 A / A to form an electron injection layer.

[0184] (9) Cathode: The magnesium and silver with a thickness of 18 nm were evaporated at an evaporation rate ratio of 1:9 to form a cathode.

[0185] (10) Light Extraction Layer: The CPL with a thickness of 70 nm was vacuum evaporated on the cathode at an evaporation rate of 0.5 A / A as a light extraction layer.

[0186] (11) The substrate after evaporation was packaged. First, the cleaned cover plate was coated with UV glue using a gluing device, then the coated cover plate was moved to the pressing section, the substrate after evaporation was placed on the upper end of the cover plate, and finally the substrate and the cover plate were bonded under the action of the bonding device, and the UV glue was cured by light at the same time.

[0187] Green light device structure:

[0188] ​​​​​​ITO / Ag / ITO / HT1-7:P-9(10 nm) / HT1-7(120 nm) / Compound 2(45 nm) / (Host-22+Host-23):Dopant-17(400 nm) / ET-12(5 nm) / ET-4:Liq(30 nm) / Yb(1 nm) / Mg:Ag(18 nm) / CPL(70 nm).

[0189] The compounds employed in each layer are as follows:

[0190]

[0191] Example 2-34

[0192] The organic electroluminescence device of Example 2-34 was produced in the same manner as in Example 1, except that the compound 2 in Example 1 was replaced by the corresponding compound, respectively, to form the light-emitting auxiliary layer.

[0193] Comparative Example 1

[0194] The organic electroluminescence device was produced in the same manner as in Example 1, except that the compound 2 in Example 1 was replaced by Comparative Compound 1, wherein the structural formula of Comparative Compound 1 is as follows:

[0195] Comparative Example 2

[0196] The organic electroluminescence device was produced in the same manner as in Example 1, except that the compound 2 in Example 1 was replaced by Comparative Compound 2, wherein the structural formula of Comparative Compound 2 is as follows:

[0197] Comparative Example 3

[0198] The organic electroluminescence device was produced in the same manner as in Example 1, except that the compound 2 in Example 1 was replaced by Comparative Compound 3, wherein the structural formula of Comparative Compound 3 is as follows:

[0199] Comparative Example 4

[0200] The organic electroluminescence device was produced in the same manner as in Example 1, except that the compound 2 in Example 1 was replaced by Comparative Compound 4, wherein the structural formula of Comparative Compound 4 is as follows:

[0201] Comparative Example 5

[0202] The organic electroluminescence device was produced in the same manner as in Example 1, except that the compound 2 in Example 1 was replaced by Comparative Compound 5, wherein the structural formula of Comparative Compound 5 is as follows:

[0203] Comparative Example 6

[0204] An organic electroluminescent device was prepared according to the method of Application Example 1, except that the compound 2 in Application Example 1 was replaced by Comparative Compound 6, wherein the structural formula of Comparative Compound 6 is as follows:

[0205]

[0206] Test Example 1

[0207] The performance of the organic electroluminescent devices prepared in the application examples and comparative examples was tested, and the luminous efficiency and the lifetime of the organic electroluminescent devices obtained from the above device application examples 1-34 and device comparative examples 1-6 were characterized at a brightness of 15000 (nits), and the test results are as shown in Table 2 below:

[0208] Table 2 Test results of luminous properties (brightness value is 15000 nits)

[0209]

[0210]

[0211] It can be seen from the above Table 2 that the compounds represented by Formula I, application examples 1 to 34, exhibit higher luminous efficiency and longer lifetime than the comparative examples.

[0212] The present application speculates that the possible reason for this manifestation is that the substitution position of the arylamine group affects the degree of spatial distortion of the compound, and the alkyl group regulates the benzene ring, which comprehensively affects the overall performance of the device.

[0213] Test Example 2

[0214] Test the dihedral angle and simulate the density, simulate the dihedral angle of the compound by Gaussian software, select the two planes adjacent to the N atom to simulate and calculate. The disordered stacking density of the thin film is simulated by the NPT method in molecular dynamics, and the results are as shown in Figure 4 .

[0215] It can be seen from the comparison that the compound prepared in the embodiment of the present application has a larger dihedral angle than the comparative compound.

[0216] This may be due to: the substitution position of the arylamine group affects the degree of spatial distortion of the compound, the dihedral angle increases, the molecular configuration is more distorted, and according to the two distorted planes, the crystallinity may be reduced due to the reduction of intermolecular interaction, reducing the aggregation of molecular stacking, reducing the plugging phenomenon in evaporation, at the same time, the intermolecular interaction is weakened, which can reduce the evaporation temperature of the compound, avoid the change of chemical structure caused by long time heating. On the other hand, due to the reduction of molecular aggregation, it is not easy to form carrier transport traps, which is conducive to the migration of holes, and the obtained OLED device is improved in lifetime and luminous efficiency.

[0217] The above merely provides the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. An organic electroluminescent compound, characterized in that, Its general structural formula is shown in Formula I: In Formula I, n is selected from integers from 1 to 4, and R is independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl, and phenyl. L is selected from either single bonds or phenyl groups; Ar1 and Ar2 are each independently selected from any one of dimethylfluorenyl, biphenyl, dibenzofuranyl, diphenylfluorenyl, naphthyl, carbazoleyl, and N-phenylcarbazoleyl; The organic electroluminescent compounds do not include the following compounds:

2. The organic electroluminescent compound according to claim 1, characterized in that, When n is 1, the structures of the organic electroluminescent compounds are shown in Formulas I-1 to I-4: R1-R4 are each independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl, and phenyl.

3. The organic electroluminescent compound according to claim 1, characterized in that, When n is 2, the structures of the organic electroluminescent compounds are shown in Formulas I-5 to I-10: R1-R4 are each independently selected from any one of methyl, ethyl, propyl, isopropyl, tert-butyl, and phenyl.

4. The organic electroluminescent compound according to any one of claims 1-3, characterized in that, The structure of the organic electroluminescent compound is selected from at least one of compounds 1-92:

5. A method for preparing the organic electroluminescent compound according to any one of claims 1-4, characterized in that, The target compound is prepared by reacting reactants A-I and B-I to obtain intermediate C-I, then reacting intermediate C-I under acidic conditions to obtain intermediate D-I, and finally by substituting the halogen in intermediate D-I. The reaction route is as follows:

6. The preparation method according to claim 5, characterized in that, The route for preparing intermediate D-I from reactant A-I and reactant B-I is as follows:

7. The preparation method according to claim 6, characterized in that, The process of preparing intermediate D-I from reactant A-I and reactant B-I includes: After dissolving the reactant B-Ⅰ, it was reacted with n-BuLi at -75 to -80℃ for 1-3 hours. Then, the mixed solution formed by dissolving the reactant A-Ⅰ was added dropwise to the reaction system. After the addition was completed, the temperature was raised to terminate the reaction. The organic phase was collected by liquid separation and then separated to obtain the intermediate C-Ⅰ. The intermediate C-I was dissolved in HOAC and H2SO4 was added dropwise at 90-110℃. The reaction was carried out for 0.5-2 hours. After the reaction was terminated, the organic phase was collected by liquid separation and then the intermediate D-I was obtained.

8. The preparation method according to claim 5, characterized in that, When L is a single bond, the reaction route for preparing the target compound from the intermediate D-Ⅰ is as follows:

9. The preparation method according to claim 8, characterized in that, The process for preparing the target compound from the intermediate D-Ⅰ includes: dissolving the intermediate D-Ⅰ and reactant E-Ⅰ, and then reacting them in the presence of Pd2(dba)3, P(t-Bu)3 and t-BuONa, controlling the reaction temperature at 105-115℃ and the reaction time at 6-10h; after the reaction is complete, filtering is performed, the filtrate is cooled and the solvent is removed by rotary evaporation, the obtained solid is dried and eluted, the eluted filtrate is rotary evaporated, and the solid obtained by rotary evaporation is dried to obtain the compound of general formula I.

10. The preparation method according to claim 5, characterized in that, When L is not a single bond, the reaction route for preparing the target compound from intermediate D-Ⅰ is as follows:

11. The preparation method according to claim 10, characterized in that, After dissolving the intermediate D-I and reactant E-I, the reaction was carried out in the presence of Pd(PPh)4 and potassium carbonate, with the reaction temperature controlled at 110-120℃ and the reaction time at 8-12h. After the reaction was completed, the mixture was filtered, and the solvent was removed by rotary evaporation after cooling the filtrate. The obtained solid was dried and then eluted. The eluted filtrate was then rotary evaporated, and the solid obtained by rotary evaporation was dried to obtain the compound of general formula I.

12. An organic material layer, characterized in that, It is prepared by any one of the organic electroluminescent compounds according to claims 1-4.

13. The organic material layer according to claim 12, characterized in that, The organic material layer includes a light-emitting auxiliary layer, which is prepared by the organic electroluminescent compound.

14. The organic material layer according to claim 13, characterized in that, The organic material layer comprises, in sequence, a hole injection layer, a hole transport layer, a light-emitting auxiliary layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer.

15. An organic electroluminescent device, characterized in that, It includes an anode, a cathode, and an organic material layer as described in any one of claims 12-14, the organic material layer being located between the anode and the cathode.

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