An organic electroluminescence naphthofuran compound and a preparation method and application thereof

Abstract

The application provides an organic electroluminescence naphthofuran compound and application thereof in preparation of an organic electroluminescence device, a structural general formula is shown in the description, the compound of the application uses benzofuran as a mother nucleus and is connected into an asymmetric spiro ring, on one hand, the symmetry of the spiro ring is destroyed, the spatial steric hindrance of the compound is increased, the life and thermal stability of the compound are improved, an electron-withdrawing side chain is used for modification, the electron transport capacity of the compound is improved, the transmission material with high electron mobility can increase the probability of formation of excitons, reduce the leakage current formed due to excessive holes in the device, the holes are transmitted to the cathode in the device, the luminous brightness and efficiency of the device can be improved. The preparation method of the luminescent compound of the application is simple, the synthesis route is short, raw materials are easy to obtain, the obtained crude product is easy to purify, high-purity luminescent auxiliary layer materials can be obtained, and the application is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of organic optoelectronic materials technology, specifically to an organic electroluminescent naphthofuran compound, its preparation method, and its application. Background Technology

[0002] With the rapid development of information technology, people have put forward new goals and requirements for the performance of information display systems. High brightness, high resolution, wide viewing angle, and low energy consumption have become research hotspots for displays. Organic light-emitting diode (OLED) display technology can meet the above-mentioned needs, and also has other advantages such as a wide operating temperature range and the ability to achieve flexible displays. Therefore, following CRT (cathode ray tube) displays, LCD (liquid crystal display), and PDP (plasma display) flat panel displays, it has become the new favorite of the next generation of flat panel displays. Organic light-emitting diode (OLED) display technology is also known as a flat panel display technology with dreamlike display characteristics.

[0003] Typically, OLED light-emitting devices consist of a hole injection layer, a hole transport layer, an emissive layer, an electron transport layer, and an electron injection layer. The hole transport layer (HTL) regulates the injection rate and quantity of holes, while the electron transport layer (ETL) regulates the injection rate and quantity of electrons. Organic materials generally have very low electron mobility, while hole mobility is 10-100 times higher than electron mobility. This electron-hole imbalance within the device leads to reduced efficiency, faster efficiency decay, and decreased stability.

[0004] To improve electron injection and transport, high-mobility electron injection and transport materials are required. Electron transport materials need to have a high glass transition temperature (Tg). Commonly used electron transport materials include Bphen, TPBi, BCP, BAlq, and TAZ. In some light-emitting devices, especially blue light devices, the triplet energy level of the electron transport material needs to be higher than that of the luminescent dye to effectively confine excitons within the emitting layer. Electron transport materials typically require a low LUMO energy level and generally contain electron-withdrawing groups such as halogens, pyridines, triazines, triazoles, and hydroxyl groups to facilitate electron gain and transport. Furthermore, the LUMO energy level should be matched as closely as possible to the work function of the cathode to maximize electron injection and transport. Simultaneously, the HOMO of the electron transport material should be as large as possible to block the transport of holes from the emitting layer to the cathode, allowing more holes to be confined within the emitting layer to form excitons and generate light. Therefore, electron transport materials are often also referred to as hole-blocking materials.

[0005] Therefore, developing an organic electroluminescent naphthofuran compound, its preparation method, and its application are technical problems that urgently need to be solved by those in the field. Summary of the Invention

[0006] In view of this, the present invention provides an organic electroluminescent naphthofuran compound, a method for preparing the same, and its application in the preparation of organic electroluminescent devices.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] An organoluminescent naphthofuran compound, the general structural formula of which is shown in Formula I:

[0009]

[0010] In this case, any one of m, n, and p is 1, and the rest are 0;

[0011] q is a positive integer, and 1≤q≤4;

[0012] X is a linker bond, or can be selected from: O, S, SiR6R7, CR8R9, or NR. 10 ;

[0013] At least one of X1-X3 is N, and the rest are C;

[0014] R1-R4, R6-R 10 Each is independently selected from: hydrogen, deuterium, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C2-C30 alkynyl, substituted or unsubstituted 3-30 cycloalkyl, substituted or unsubstituted 3-30 heterocycloalkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted 3-30 heteroaryl, substituted or unsubstituted 3-30 heteroarylamine, substituted or unsubstituted C6-C60 arylamine, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C6-C60 aryloxy; or connected with adjacent substituents to form a monocyclic, C3-C30 aliphatic, or 3-30 aromatic ring;

[0015] The positions of R1-R4 are any positions on the benzene ring;

[0016] R5 is selected from: substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted 3-30 heteroaryl, substituted or unsubstituted C10-C30 fused ring group, substituted or unsubstituted 3-30 heteroarylamine, substituted or unsubstituted C6-C60 arylamine, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C10-C30 spirocyclic group, or connected with adjacent substituents to form a monocyclic, C3-C30 aliphatic or C6-C30 aromatic ring;

[0017] L1 and L2 are connecting bonds, or are independently selected from: substituted or unsubstituted C6-C30 aryl groups, substituted or unsubstituted 3-30 heteroaryl groups, and substituted or unsubstituted C10-C60 fused ring groups.

[0018] Furthermore, in the C3-C30 aliphatic ring or 3-30 aromatic ring formed by the independent connection of R1-R4 and R6-R10 with adjacent substituents, at least one carbon atom is replaced by nitrogen, oxygen or sulfur.

[0019] If the above R5 is connected with an adjacent substituent to form a C3-C30 aliphatic ring or a C6-C30 aromatic ring, then at least one carbon atom is replaced by nitrogen, oxygen, sulfur or silicon.

[0020] Preferably, R1-R4 and R6-R9 are each independently selected from: methyl, ethyl, propyl, tert-butyl, alkoxy, alkoxy-mercapto, aryloxy, phenyl, biphenyl, naphthyl, dimethylfluorenyl, diphenylfluorenyl or spirocyclic.

[0021] R5 is selected from: naphthyl, anthracene, phenanthrene, benzo[a]phenanthrene, phenyl, carbazole, tert-butylbenzene, methylphenyl, terphenyl, biphenyl, dibenzofuran, dibenzothiophene, fluorene or spiro and their derivatives.

[0022] The term "substituted or unsubstituted" means substituted by one, two or more substituents selected from the following: deuterium; halogen group; nitrile group; hydroxyl group; carbonyl group; ester group; silyl group; boron group; substituted or unsubstituted alkyl group; substituted or unsubstituted cycloalkyl group; substituted or unsubstituted alkoxy group; substituted or unsubstituted alkenyl group; substituted or unsubstituted alkylamino group; substituted or unsubstituted heterocyclic amino group; substituted or unsubstituted arylamino group; substituted or unsubstituted aryl group; substituted or unsubstituted heterocyclic group; or substituted by a substituent linked to two or more substituents listed above, or without substituents. For example, "substituent linked to two or more substituents" can include biphenyl, in other words, biphenyl can be aryl, or can be interpreted as a substituent linked to two phenyl groups.

[0023] Preferably, the above-mentioned organoelectroluminescent naphthofuran compounds have the structural formula of any one of the following:

[0024]

[0025]

[0026]

[0027] This invention also provides a method for preparing the above-mentioned organoelectroluminescent naphthofuran compound, comprising the following steps:

[0028] (1) Add reactant A to the reaction vessel, add tetrahydrofuran, cool under nitrogen protection, then add n-BuLi dropwise and stir;

[0029] Reactant B was dissolved in tetrahydrofuran and then added dropwise to the reaction vessel. After the addition was complete, the temperature was raised to room temperature, stirred, and distilled water was added to terminate the reaction. The organic phase was collected by separation, dried, filtered, and the solvent was removed to obtain a solid organic compound.

[0030] Ethyl acetate and ethanol were added to the solid organic compound and heated to reflux. The mixture was stirred, filtered, and the filter cake was washed with petroleum ether and dried to obtain intermediate C.

[0031] (2) Add intermediate C to glacial acetic acid, heat, add concentrated sulfuric acid dropwise, stir, cool to room temperature, add sodium bicarbonate solution to terminate the reaction, and separate the liquids.

[0032] The aqueous phase was extracted with dichloromethane, the organic phase was collected, dried, filtered, and the solvent was removed to obtain a solid organic compound;

[0033] The solid organic compound was added to toluene for recrystallization, filtered, and the filter cake was washed with petroleum ether and dried to obtain intermediate D.

[0034] (3) Under nitrogen protection, intermediate D, reactant E, tetra(triphenylphosphine)palladium and potassium carbonate were added to a mixed solvent of toluene, ethanol and water. The mixture was heated to reflux and reacted. After the reaction was completed, the mixture was cooled to room temperature, washed with water, filtered, dried, and recrystallized in 1,4-dioxane to obtain an organic electroluminescent naphthofuran compound as shown in chemical formula I.

[0035] The synthetic route for the above-mentioned organo-electroluminescent naphthofuran compounds, as shown in Formula I, is as follows:

[0036]

[0037] Furthermore, in step (1), the molar ratio of reactant A, n-BuLi and reactant B is 1:1-1.2:1-1.2.

[0038] Further, in step (1), the temperature is lowered to -78°C, n-BuLi is added dropwise, and the mixture is stirred at -78°C for 2-4 hours. Reactant B is dissolved in tetrahydrofuran and then added dropwise to the reaction vessel. After the addition is complete, the temperature is raised to room temperature and stirred for 8-10 hours. After concentration, ethyl acetate and ethanol are added to the solid organic matter and heated to 80°C for reflux. The mixture is stirred for 3-6 hours, filtered, and the filter cake is washed with petroleum ether and dried in a 65°C oven for 12 hours to obtain intermediate C.

[0039] Furthermore, in step (2), the ratio of the above intermediate C, glacial acetic acid, concentrated sulfuric acid, and sodium bicarbonate solution is 1 mol: 4-6 mL: 0.05-0.15 mL: 4-6 mL, and the sodium bicarbonate solution is a saturated sodium bicarbonate solution.

[0040] Further, in step (2), intermediate C is added to glacial acetic acid, heated to 120°C, the filter cake is washed with petroleum ether, and dried in an 80°C oven for 8-12 hours to obtain intermediate D.

[0041] Furthermore, in step (3), the molar ratio of intermediate D, reactant E, tetra(triphenylphosphine)palladium, and potassium carbonate is 1:1-1.2:0.01:2; and the volume ratio of toluene, ethanol, and water is 2-4:1:1.

[0042] Furthermore, in step (3), the temperature is raised to reflux for 8 hours.

[0043] The present invention also provides an application of the above-mentioned organic electroluminescent naphthofuran compounds in the preparation of organic electroluminescent devices.

[0044] The present invention also provides an organic electroluminescent device, characterized in that it comprises a first electrode, an organic electroluminescent material layer, and a second electrode deposited sequentially by vapor deposition; wherein the organic electroluminescent material layer comprises the aforementioned organic electroluminescent naphthofuran compound.

[0045] Furthermore, the aforementioned organic electroluminescent material layer includes one or more layers selected from the following sequentially vapor-deposited layers: a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, a hole blocking layer, and an electron blocking layer, and at least one of these layers includes the aforementioned organic electroluminescent naphthuran compound.

[0046] The beneficial effects of the present invention are: (1) The compound of the present invention uses benzofuran as the parent nucleus and connects them into an asymmetric spiro ring, which on the one hand destroys the symmetry of the spiro ring, increases the steric hindrance of the compound, and improves the lifetime and thermal stability of the compound.

[0047] (2) Modification with electron-withdrawing side chains improves the electron transport capability of the compound. High electron mobility transport materials can increase the probability of exciton formation and reduce leakage current caused by the excessive number of holes in the device being transported through the device to the cathode. This can improve the brightness and efficiency of the device.

[0048] (3) The method for preparing the luminescent compound of the present invention is simple, the synthesis route is short, the raw materials are readily available, the crude product is easy to purify, and high-purity luminescent auxiliary layer material can be obtained, which is suitable for industrial production. Detailed Implementation

[0049] The following embodiments are provided to illustrate the present invention in detail, and are merely preferred embodiments, not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] Example 1: Synthesis of Compound 1

[0051]

[0052] (1) Add reactant A-1 (80 mmol) to a three-necked flask, add 400 mL of anhydrous tetrahydrofuran, purge with nitrogen three times, then cool the reaction system to -78 °C, add (2.5 M) n-BuLi (88 mmol) dropwise, and stir for 2 h. Dissolve reactant B-1 (88 mmol) in tetrahydrofuran and add it dropwise to the reaction system. After the addition is complete, heat to room temperature and stir for 10 h. Add distilled water to terminate the reaction, collect the organic phase by separation, and dry with anhydrous magnesium sulfate. Remove the remaining water, filter to remove anhydrous magnesium sulfate, and remove the solvent from the organic phase using a rotary evaporator to obtain a solid organic compound. After concentration, 100 mL of ethyl acetate and 400 mL of ethanol were added to the solid organic matter and heated to 80 °C under reflux. The mixture was stirred for 3 h and filtered to obtain a solid. The filter cake was washed with 200 mL of petroleum ether and dried in an oven at 65 °C for 12 h to obtain intermediate C-1 (22.8 g, yield: 76%, Ms: 374.54).

[0053] (2) Add intermediate C-1 (60 mmol) to a three-necked flask, add 300 mL of glacial acetic acid, heat to 120 °C, slowly add 6 mL of concentrated sulfuric acid dropwise using a burette, and stir for 5 min. Cool to room temperature, add 300 mL of sodium bicarbonate solution to terminate the reaction, separate the liquid and extract the aqueous phase three times with 500 mL of dichloromethane, collect the organic phase, dry with anhydrous magnesium sulfate, remove the remaining water, filter to remove anhydrous magnesium sulfate, remove the solvent from the organic phase by rotary evaporation to obtain solid organic matter, recrystallize in 180 mL of toluene, filter, wash the filter cake with 150 mL of petroleum ether, and dry in an oven at 80 °C for 12 h to obtain intermediate D-1 (18.8 g, yield: 88%, Ms: 356.74).

[0054] (3) Under nitrogen protection, intermediate D-1 (50 mmol), reactant E-1 (55 mmol), tetrakis(triphenylphosphine)palladium (0.05) and potassium carbonate (100 mmol) were added to a mixed solvent of 150 mL toluene, 50 mL ethanol and 50 mL water, respectively. The mixture was heated to reflux for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, filtered, dried, and recrystallized in 1,4-dioxane (200 mL) to obtain compound 1 (23.95 g, yield: 76%).

[0055] The obtained compound 1 was analyzed, and the results are as follows:

[0056] Mass spectrometry test: theoretical value 630.21; test value 630.45.

[0057] Elemental analysis:

[0058] Theoretical values: C, 81.89; H, 4.16; N, 8.88; O, 5.07

[0059] Test values: C, 89.91; H, 4.18; N, 8.88; O, 5.05

[0060] Example 2: Synthesis of Compound 23

[0061]

[0062] (1) Add reactant A-23 (80 mmol) to a three-necked flask, add 400 mL of anhydrous tetrahydrofuran, purge with nitrogen three times, then cool the reaction system to -78 °C, add (2.5 M) n-BuLi (88 mmol) dropwise, and stir for 2 h. Dissolve reactant B-23 (88 mmol) in tetrahydrofuran and add it dropwise to the reaction system. After the addition is complete, heat to room temperature and stir for 10 h. Add distilled water to terminate the reaction, collect the organic phase by separation, dry with anhydrous magnesium sulfate to remove the remaining water, filter to remove the anhydrous magnesium sulfate, and remove the solvent from the organic phase by rotary evaporation to obtain a solid organic compound. After concentration, 100 mL of ethyl acetate and 400 mL of ethanol were added and heated to 80 °C under reflux. The mixture was stirred for 3 h and filtered to obtain a solid. The filter cake was washed with 200 mL of petroleum ether and dried in an oven at 65 °C for 12 h to obtain intermediate C-23 (23.4 g, yield: 78%, Ms: 374.74).

[0063] (2) Add intermediate C-23 (60 mmol) to a three-necked flask, add 300 mL of glacial acetic acid, heat to 120 °C, slowly add 6 mL of concentrated sulfuric acid dropwise using a burette, and stir for 5 min. Cool to room temperature, add 300 mL of sodium bicarbonate solution to terminate the reaction, separate the liquid and extract the aqueous phase three times with 500 mL of dichloromethane, collect the organic phase, dry with anhydrous magnesium sulfate, remove the remaining water, filter to remove anhydrous magnesium sulfate, remove the solvent from the organic phase by rotary evaporation to obtain solid organic matter, recrystallize in 180 mL of toluene, filter, wash the filter cake with 150 mL of petroleum ether, and dry in an oven at 80 °C for 12 h to obtain intermediate D-23 (18.4 g, yield: 86%, Ms: 356.23).

[0064] (3) Under nitrogen protection, intermediate D-23 (50 mmol), reactant E-23 (55 mmol), tetrakis(triphenylphosphine)palladium (0.05) and potassium carbonate (100 mmol) were added to a mixed solvent of 150 mL toluene, 50 mL ethanol and 50 mL water, respectively. The mixture was heated to reflux for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, filtered, dried, and recrystallized in 200 mL of 1,4-dioxane to obtain compound 23 (32.5 g, yield: 81%).

[0065] The obtained compound 23 was analyzed, and the results are as follows:

[0066] Mass spectrometry test: theoretical value 801.34; test value 801.62.

[0067] Elemental analysis:

[0068] Theoretical values: C, 85.37; H, 5.40; N, 5.24; O, 3.99

[0069] Test values: C, 85.35; H, 5.38; N, 5.27; O, 4.01

[0070] Example 3: Synthesis of Compound 48

[0071]

[0072] (1) Add reactant A-48 (80 mmol) to a three-necked flask, add 400 mL of anhydrous tetrahydrofuran, purge with nitrogen three times, then cool the reaction system to -78 °C, add (2.5 M) n-BuLi (88 mmol) dropwise, and stir for 2 h. Dissolve reactant B-48 (88 mmol) in tetrahydrofuran and add it dropwise to the reaction system. After the addition is complete, heat to room temperature and stir for 10 h. Add distilled water to terminate the reaction, collect the organic phase by separation, and dry with anhydrous magnesium sulfate. Remove the remaining water, filter to remove anhydrous magnesium sulfate, and remove the solvent from the organic phase using a rotary evaporator to obtain a solid organic compound. After concentration, 100 mL of ethyl acetate and 400 mL of ethanol were added and heated to 80 °C under reflux. The mixture was stirred for 3 h and filtered to obtain a solid. The filter cake was washed with 200 mL of petroleum ether and dried in an oven at 65 °C for 12 h to obtain intermediate C-48 (22.4 g, yield: 78%, Ms: 358.71).

[0073] (2) Add intermediate C-48 (60 mmol) to a three-necked flask, add 300 mL of glacial acetic acid, heat to 120 °C, slowly add 6 mL of concentrated sulfuric acid dropwise using a burette, and stir for 5 min. Cool to room temperature, add 300 mL of sodium bicarbonate solution to terminate the reaction, separate the liquid and extract the aqueous phase three times with 500 mL of dichloromethane, collect the organic phase, dry with anhydrous magnesium sulfate, remove the remaining water, filter to remove anhydrous magnesium sulfate, remove the solvent from the organic phase by rotary evaporation to obtain solid organic matter, recrystallize in 180 mL of toluene, filter, wash the filter cake with 150 mL of petroleum ether, and dry in an oven at 80 °C for 12 h to obtain intermediate D-48 (18.4 g, yield: 90%, Ms: 340.07).

[0074] (3) Under nitrogen protection, intermediate D-48 (50 mmol), reactant E-48 (55 mmol), tetra(triphenylphosphine)palladium (0.05) and potassium carbonate (100 mmol) were added to a mixed solvent of 150 mL toluene, 50 mL ethanol and 50 mL water, respectively. The mixture was heated to reflux and reacted for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, filtered, dried, and recrystallized in 200 mL of 1,4-dioxane to obtain compound 48 (31.4 g, yield: 79%).

[0075] The obtained compound 48 was analyzed, and the results are as follows:

[0076] Mass spectrometry test: theoretical value 795.99; test value 795.66.

[0077] Elemental analysis:

[0078] Theoretical values: C, 87.52; H, 5.19; N, 5.28; O, 2.01

[0079] Test values: C, 87.53; H, 5.15; N, 5.32; O, 2.00

[0080] Example 4: Synthesis of Compound 75

[0081]

[0082] (1) Add reactant A-75 (80 mmol) to a three-necked flask, add 400 mL of anhydrous tetrahydrofuran, purge with nitrogen three times, then cool the reaction system to -78 °C, add (2.5 M) n-BuLi (88 mmol) dropwise, and stir for 2 h. Dissolve reactant B-75 (88 mmol) in tetrahydrofuran and add it dropwise to the reaction system. After the addition is complete, heat to room temperature and stir for 10 h. Add distilled water to terminate the reaction, collect the organic phase by separation, and dry with anhydrous magnesium sulfate. Remove the remaining water, filter to remove anhydrous magnesium sulfate, and remove the solvent from the organic phase using a rotary evaporator to obtain a solid organic compound. After concentration, 100 mL of ethyl acetate and 400 mL of ethanol were added and heated to 80 °C under reflux. The mixture was stirred for 3 h and filtered to obtain a solid. The filter cake was washed with 200 mL of petroleum ether and dried in an oven at 65 °C for 12 h to obtain intermediate C-75 (25.6 g, yield: 80%, Ms: 400.35).

[0083] (2) Add intermediate C-75 (60 mmol) to a three-necked flask, add 300 mL of glacial acetic acid, heat to 120 °C, slowly add 6 mL of concentrated sulfuric acid dropwise using a burette, and stir for 5 min. Cool to room temperature, add 300 mL of sodium bicarbonate solution to terminate the reaction, separate the liquid and extract the aqueous phase three times with 500 mL of dichloromethane, collect the organic phase, dry with anhydrous magnesium sulfate, remove the remaining water, filter to remove anhydrous magnesium sulfate, remove the solvent from the organic phase by rotary evaporation to obtain solid organic matter, recrystallize in 180 mL of toluene, filter, wash the filter cake with 150 mL of petroleum ether, and dry in an oven at 80 °C for 12 h to obtain intermediate D-75 (19.5 g, yield: 85%, Ms: 382.45).

[0084] (3) Under nitrogen protection, intermediate D-75 (50 mmol), reactant E (55 mmol), tetrakis(triphenylphosphine)palladium (0.05) and potassium carbonate (100 mmol) were added to a mixed solvent of 150 mL toluene, 50 mL ethanol and 50 mL water, respectively. The mixture was heated to reflux for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, filtered, dried, and recrystallized in 1,4-dioxane (150 mL) to obtain compound 75 (26.1 g, yield: 74%).

[0085] The obtained compound 75 was analyzed, and the results are as follows:

[0086] Mass spectrometry test: theoretical value 705.28; test value 705.77.

[0087] Elemental analysis:

[0088] Theoretical values: C, 86.78; H, 5.00; N, 5.95; O, 2.27

[0089] Test values: C, 86.76; H, 5.00; N, 5.94; O, 2.28

[0090] Example 5: Synthesis of Compound 95

[0091]

[0092] (1) Add reactant A-95 (80 mmol) to a three-necked flask, add 400 mL of anhydrous tetrahydrofuran, purge with nitrogen three times, then cool the reaction system to -78 °C, add (2.5 M) n-BuLi (88 mmol) dropwise, and stir for 2 h. Dissolve reactant B-95 (88 mmol) in tetrahydrofuran and add it dropwise to the reaction system. After the addition is complete, heat to room temperature and stir for 10 h. Add distilled water to terminate the reaction, collect the organic phase by separation, and dry with anhydrous magnesium sulfate. Remove the remaining water, filter to remove anhydrous magnesium sulfate, and remove the solvent from the organic phase using a rotary evaporator to obtain a solid organic compound. After concentration, 100 mL of ethyl acetate and 400 mL of ethanol were added and heated to 80 °C under reflux. The mixture was stirred for 3 h and filtered to obtain a solid. The filter cake was washed with 200 mL of petroleum ether and dried in an oven at 65 °C for 12 h to obtain intermediate C-95 (22.1 g, yield: 77%, Ms: 358.25).

[0093] (2) Add intermediate C-95 (60 mmol) to a three-necked flask, add 300 mL of glacial acetic acid, heat to 120 °C, slowly add 6 mL of concentrated sulfuric acid dropwise using a burette, and stir for 5 min. Cool to room temperature, add 300 mL of sodium bicarbonate solution to terminate the reaction, separate the liquid and extract the aqueous phase three times with 500 mL of dichloromethane, collect the organic phase, dry with anhydrous magnesium sulfate, remove the remaining water, filter to remove anhydrous magnesium sulfate, remove the solvent from the organic phase by rotary evaporation to obtain solid organic matter, recrystallize in 180 mL of toluene, filter, wash the filter cake with 150 mL of petroleum ether, and dry in an oven at 80 °C for 12 h to obtain intermediate D-95 (18.0 g, yield: 88%, Ms: 340.77).

[0094] (3) Under nitrogen protection, intermediate D-95 (50 mmol), reactant E-95 (55 mmol), tetra(triphenylphosphine)palladium (0.05) and potassium carbonate (100 mmol) were added to a mixed solvent of 150 mL toluene, 50 mL ethanol and 50 mL water, respectively. The mixture was heated to reflux for 8 h. After the reaction was completed, the mixture was cooled to room temperature, washed with water, filtered, dried, and recrystallized in 1,4-dioxane (150 mL) to obtain compound 95 (25.2 g, yield: 76%).

[0095] The obtained compound 95 was analyzed, and the results are as follows:

[0096] Mass spectrometry test: theoretical value 663.56; test value: 663.42.

[0097] Elemental analysis:

[0098] Theoretical values: C, 86.86; H, 4.40; N, 6.33; O, 2.41

[0099] Test values: C, 86.85; H, 4.40; N, 6.32; O, 2.42

[0100] Examples 6 to 22

[0101] Compounds 5, 13, 18, 29, 32, 38, 42, 50, 56, 62, 67, 77, 84, 88, 90, 99, and 105 were synthesized according to the synthetic methods described in Examples 1 to 5. The mass spectra, molecular formulas, and yields are shown in Table 1.

[0102] Table 1:

[0103]

[0104]

[0105] Device Example 1: Fabrication of an organic electroluminescent device containing compound 1:

[0106] The Fisher coating thickness is The ITO glass substrate was washed twice with distilled water, ultrasonically cleaned for 30 minutes, repeatedly washed twice with distilled water, and ultrasonically cleaned for 10 minutes. After the distilled water cleaning was completed, the substrate was ultrasonically cleaned in sequence with solvents such as isopropanol, acetone, and methanol, and then dried. It was then transferred to a plasma cleaning machine, cleaned for 5 minutes, and sent to a vapor deposition machine.

[0107] A 60 nm thick layer of 4,4',4”-tris[2-naphthylphenylamino]triphenylamine (2-TNATA) was deposited on a prepared ITO transparent electrode as a hole injection layer. A 30 nm thick layer of N'-bis(1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (NPB) was then vacuum-deposited on top of the hole injection layer as a hole transport layer. Subsequently, a 20 nm thick layer of 4,4'-N,N'-biphenyl dicarbazole ("CBP") was deposited on the hole transport layer as the host material (95%), along with a 5% (btp)₂Ir(acac)-doped fumed silica. Light-emitting materials. Next, a 10 nm thick layer of bis(2-methyl-8-hydroxyquinoline-N1,08)-(1,1'-biphenyl-4-hydroxy)aluminum (BAlq) was vacuum-deposited on the aforementioned light-emitting layer as a hole-blocking layer. A 50 nm thick layer of compound 1 was then vacuum-deposited on the hole-blocking layer as an electron transport layer. A 0.5 nm thick layer of lithium fluoride (LiF) was then vacuum-deposited on the electron transport layer as an electron injection layer. Finally, a 150 nm thick aluminum layer was deposited as the cathode, thus completing the fabrication of the organic electroluminescent device. The performance and luminescence characteristics of the obtained device were tested. This completed the fabrication of the organic electroluminescent device.

[0108] Following the above method, the compound 1 used in Device Example 1 was replaced with 5, 13, 18, 23, 29, 32, 38, 42, 48, 50, 56, 62, 67, 75, 77, 84, 88, 90, 95, 99, and 105 as electron transport layers, respectively, to prepare corresponding organic electroluminescent devices as Device Examples 1-22.

[0109] Device Comparison Example 1

[0110] The organic electroluminescent device was prepared using the same method as in Device Example 1, and the electron transport layer compound adopted the following structure:

[0111]

[0112] Device Comparison Example 2

[0113] The organic electroluminescent device was prepared using the same method as in Device Example 1, and the electron transport layer compound adopted the following structure:

[0114]

[0115] The organic electroluminescent device prepared above was subjected to a forward DC bias voltage, and its organic electroluminescence characteristics were measured using a PhotoResearch PR-650 photometric instrument. The results were obtained at 8000 cd / m². 2The lifetime of T95 was measured using a McScience lifetime testing device at a reference gray level. The results are shown in Table 2.

[0116] Device structure: ITO / 2-TNATA / NPB / CBP:(btp)2Ir(acac) / BAlq / compound1 / LiF / Al.

[0117] After completing the OLED light-emitting device as described above, the anode and cathode are connected using a known driving circuit, and the current efficiency and lifetime of the device are measured. After completing the fabrication of the electroluminescent device according to the above steps, the driving voltage, luminous efficiency, and lifetime of the device are measured.

[0118] The molecular structural formulas of the relevant materials are shown below:

[0119]

[0120] Table 2: Test results of luminous properties of the device in Examples 1-22 and Comparative Examples 1-2 of the present invention (luminance value 8000 cd / m²) 2 )

[0121]

[0122]

[0123] Overall, compared with the structurally similar comparative compound 1, the driving voltage is reduced by 0.8-1.5V, the luminous efficiency is improved by 10-15.8%, and the device lifetime is improved by 61-117h.

[0124] Compared with the traditional electron transport material BCP (comparative compound 2), the prepared compound showed significant improvements in driving voltage, luminous efficiency, and lifetime performance.

[0125] The main difference between this invention and comparative compound 1 is that the compound of this invention uses naphthofuran as the parent nucleus to form a ring, while comparative compound 1 adopts a symmetrical spirocyclic structure. On the one hand, the symmetry of the spirocyclic structure is disrupted, increasing the steric hindrance of the compound and improving its lifetime and thermal stability. On the other hand, the use of electron-withdrawing side chains for modification improves the electron transport capability of the compound. High electron mobility transport materials can increase the probability of exciton formation, reduce leakage current caused by excess holes in the device, which leads to holes being transported through the device to the cathode, and thus improve the brightness and efficiency of the device.

[0126] The above description is merely a simplified illustration of the present invention. The application of the present invention is not limited to the examples given above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the claims of the present invention. If the embodiments of the present invention are merely for illustrative purposes, the scope of the invention is not limited to this scope. The protection scope of the present invention must be interpreted within the scope of the following claims, and all technologies with the same scope as the present invention are included within the rights of the present invention.

Claims

1. An organic electroluminescent naphthofuran compound, characterized in that, The organic electroluminescent naphthofuran compound has the structural formula of any one of the following:

2. The application of the organic electroluminescent naphthofuran compound according to claim 1 in the preparation of organic electroluminescent devices.

3. An organic electroluminescent device, characterized in that, It includes a first electrode, an organic electroluminescent material layer, and a second electrode, which are sequentially vapor-deposited; wherein the organic electroluminescent material layer includes the organic electroluminescent naphthuran compound of claim 1.

Images