Organic electroluminescent elements

Abstract

The present invention provides an organic electroluminescent element. The organic electroluminescent element includes a hole transport region, a light-emitting layer and an electron transport region sequentially arranged from an anode to a cathode, the hole transport region contains a compound of general formula (1), the electron transport region contains a compound of general formula (2), R1 to R8 are identical or different, and are hydrogen, deuterium, C1-C4 alkyl, C6-C30 aryl, or are optionally combined with adjacent groups to form a ring; Ar1 ​​and Ar2 are identical or different, and are C6-C30 aryl, L1 to L3 are identical or different, and are direct bonds or C6-C18 arylene; in general formula (2), Py is unsubstituted pyridyl; R9 is selected from hydrogen, C1-C4 alkyl or C6-C18 aryl; Ar3 is selected from C6-C18 aryl or heteroaryl; L4 is selected from direct bonds or unsubstituted phenylene; At least one of Z1 to Z3 is N, and the others are CH, and the driving voltage is lower.

Description

Technical Field

[0001] The present invention relates to an organic electroluminescent element, and more particularly to an organic electroluminescent element. Background Art

[0002] Organic electroluminescent elements are currently used in smart phones, tablet computers, automotive and other fields due to their characteristics of light weight, wide viewing angle, high contrast, low power consumption, high response speed, full-color display, and flexibility, and are expanding to large-size application areas such as televisions.

[0003] Organic electroluminescent devices typically include multiple layers, including a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. Holes and electrons are injected from the anode and cathode, respectively, pass through the transport layer into the light-emitting layer, and then recombine with each other to emit light. The efficiency of the device depends on the probability of hole and electron recombination, so regulating the balance of carriers at both ends is crucial. Key approaches include: improving the injection and transport properties of holes and electrons, thereby increasing the probability of hole-electron recombination; and improving the blocking properties of holes and electrons, thereby confining the generated excitons within the light-emitting layer to achieve high luminous efficiency. Therefore, the role played by hole transport materials and electron transport materials is extremely important.

[0004] The organic electroluminescent elements disclosed in the prior art have been reported to use arylamine compounds as hole transport layers and pyrimidine compounds as electron transport layers. The driving voltage, efficiency and life of the resulting light-emitting elements have been improved to a certain extent, but are still not sufficient and need to be further improved. Summary of the Invention

[0005] The main purpose of the present invention is to provide an organic electroluminescent element to further reduce the driving voltage of the light-emitting element.

[0006] To achieve the above-mentioned object, the present application provides an organic electroluminescent element, comprising a hole transport region, a light-emitting layer, and an electron transport region arranged in sequence from an anode to a cathode, wherein the hole transport region contains a compound represented by the general formula (1), and the electron transport region contains a compound represented by the general formula (2):

[0007]

[0008] In the general formula (1), R1 to R8 are the same or different from each other and are each independently hydrogen, deuterium, a substituted or unsubstituted C1-C4 alkyl group, a C6-C30 aryl group, or optionally combined with an adjacent group to form a substituted or unsubstituted ring; Ar1 ​​and Ar2 are the same or different from each other and are each independently substituted or unsubstituted C6-C30 aryl group, L1 to L3 are the same or different from each other and are each independently a direct bond, or a substituted or unsubstituted C6-C18 arylene group; in the general formula (2), Py is an unsubstituted pyridyl group; R9 is selected from hydrogen, a C1-C4 alkyl group or a substituted or unsubstituted C6-C18 aryl group; Ar3 is selected from a substituted or unsubstituted C6-C18 aryl group or heteroaryl group; L4 is selected from a direct bond or an unsubstituted phenylene group; at least one of Z1 to Z3 is N, and the others are CH.

[0009] Furthermore, the compound represented by the general formula (1) is represented by any one of the general formulas (1-A), (1-B) and (1-C).

[0010] Furthermore, in the compound represented by general formula (1), R1 to R8 are all H, L3 is a direct bond, L1 and L2 are direct bonds, Ar1 and Ar2 are unsubstituted C6-C25 aromatic groups; preferably, the unsubstituted C6-C25 aromatic group is biphenyl, terphenyl, naphthalene or anthracene; more preferably, the biphenyl is o-biphenyl, m-biphenyl or p-biphenyl.

[0011] Furthermore, the compound represented by the general formula (1) is selected from any one of compounds 1-1 to 1-48.

[0012] Furthermore, in the nitrogen-containing heterocyclic compound represented by general formula (2), Py is a pyridyl group, R is a phenyl group, Ar3 is a phenyl group or a naphthyl group, and L is a phenylene group; preferably, the compound represented by general formula (2) is selected from any one of compounds 2-1 to 2-36.

[0013] Furthermore, the hole transport region includes any one of a hole injection layer, a hole transport layer, a buffer layer and an electron blocking layer; or the hole transport region includes any multiple layers of a hole injection layer, a hole transport layer, a buffer layer and an electron blocking layer arranged in sequence from the anode to the cathode, wherein at least one layer of any multiple layers contains a compound represented by general formula (1).

[0014] Furthermore, the electron transport region includes any one of an electron injection layer, an electron transport layer, a buffer layer and a hole blocking layer; or the electron transport region includes any multiple layers of a hole blocking layer, a buffer layer, an electron transport layer and an electron injection layer arranged in sequence from the anode to the cathode, and at least one layer of any multiple layers contains the compound represented by general formula (2).

[0015] Furthermore, the light-emitting layer is composed of at least a host matrix and a guest dopant mixed together.

[0016] Furthermore, the main matrix is ​​an anthracene compound represented by general formula (3).

[0017] Furthermore, the guest dopant of the light-emitting layer is a fluorescent dye represented by general formula (4).

[0018] The organic electroluminescent element provided by the present invention adopts the compound represented by the general formula (1) as a hole transport layer, wherein carbazole is substituted at the ortho position of the benzene ring, and the compound is in a conjugated broken state, so it has a large band gap, and the energy level of the compound can be adjusted by introducing different substituents; further adopts the compound represented by the general formula (2) as an electron transport layer, wherein a pyridine group and a nitrogen-containing heterocycle are introduced on the phenanthrene ring, thereby improving the electron transport ability of the compound and further improving the thermal stability of the compound. Similarly, the energy level of the compound can be adjusted by introducing different substituents on the nitrogen-containing heterocycle. The combined use of the two reduces the voltage of the organic electroluminescent element, significantly improves the efficiency, and significantly improves the lifespan.

[0019] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application. DETAILED DESCRIPTION

[0020] The present invention will be described in detail below with reference to the embodiments, but the scope of the present invention is not limited thereto.

[0021] As mentioned in the background technology, the driving voltage of existing organic electroluminescent elements is still relatively high. In order to further reduce the driving voltage, this application studies and screens the matching of hole transport materials and electron transport materials in existing light-emitting elements, and further finds that by matching hole transport materials with specific structures with electron transport materials with specific structures, a lower driving voltage can be obtained, thereby obtaining an organic electroluminescent element with further improved element efficiency and life.

[0022] Based on the above research, the applicant has proposed the technical solution of the present application. In a typical embodiment, an organic electroluminescent element is provided, comprising a hole transport region, a light-emitting layer, and an electron transport region arranged in sequence from an anode to a cathode, wherein the hole transport region contains a compound represented by the general formula (1), and the electron transport region contains a compound represented by the general formula (2):

[0023]

[0024] In the general formula (1), R1 to R8 are the same or different from each other and are each independently hydrogen, deuterium, a substituted or unsubstituted C1-C4 alkyl group, a C6-C30 aryl group, or optionally combined with an adjacent group to form a substituted or unsubstituted ring; Ar1 ​​and Ar2 are the same or different from each other and are each independently substituted or unsubstituted C6-C30 aryl group, L1 to L3 are the same or different from each other and are each independently a direct bond, or a substituted or unsubstituted C6-C18 arylene group; in the general formula (2), Py is an unsubstituted pyridyl group; R9 is selected from hydrogen, a C1-C4 alkyl group or a substituted or unsubstituted C6-C18 aryl group; Ar3 is selected from a substituted or unsubstituted C6-C18 aryl group or heteroaryl group; L4 is selected from a direct bond or an unsubstituted phenylene group; at least one of Z1 to Z3 is N, and the others are CH.

[0025] In the present application, through the optimized combination of hole transport materials and electron transport materials, the compound represented by general formula (1) has good thermal stability and excellent hole transport ability, and the compound represented by general formula (3) contains planar groups, phenanthrenyl, pyridyl and triazine electronegative groups. Such a molecular structure is not easy to crystallize due to large steric hindrance, and has improved thermal stability and excellent electron transport ability. Therefore, the combination of the two is more beneficial to the injection and transport of holes and electrons on both sides, as well as balanced recombination in the light-emitting layer, thereby improving device efficiency.

[0026] In a preferred embodiment, the compound represented by general formula (1) is represented by any one of the following general formulas (1-A), (1-B) and (1-C):

[0027]

[0028] In the general formulae (1-A), (1-B) and (1-C), R1 to R8, Ar1 and Ar2, and L1 to L3 are the same as defined in the general formula (1).

[0029] In a preferred embodiment, in the compounds represented by general formulas (1-A), (1-B) and (1-C), R1 to R8 are all H, L3 is a direct bond, L1 and L2 are direct bonds, and Ar1 and Ar2 are unsubstituted C6-C25 aromatic groups; preferably, the unsubstituted C6-C25 aromatic groups are biphenyl, terphenyl, naphthalene or anthracene; more preferably, the biphenyl is o-biphenyl, m-biphenyl or p-biphenyl.

[0030] In a preferred embodiment, in the compound represented by general formula (1), R1 to R8 are all H, L3 is a direct bond, L1 and L2 are direct bonds, and Ar1 and Ar2 are unsubstituted C6-C25 aromatic groups; preferably, the unsubstituted C6-C25 aromatic groups are biphenyl, terphenyl, naphthalene or anthracene; more preferably, the biphenyl is o-biphenyl, m-biphenyl or p-biphenyl.

[0031] In a preferred embodiment, the compound represented by general formula (1) is selected from any one of the following:

[0032]

[0033]

[0034]

[0035] In a preferred embodiment, Py in the nitrogen-containing heterocyclic compound represented by general formula (2) is a pyridyl group, R is a phenyl group, Ar3 is a phenyl group or a naphthyl group, and L is a phenylene group; more preferably, the compound represented by general formula (2) is selected from any one of the following:

[0036]

[0037]

[0038]

[0039] In the above-mentioned organic electroluminescent element, the hole transport region may be one layer or multiple layers. When it is a single layer, the hole transport region includes any one of a hole injection layer, a hole transport layer, a buffer layer, and an electron blocking layer; when it is a multiple layer, the hole transport region includes any one of a hole injection layer, a hole transport layer, a buffer layer, and an electron blocking layer arranged in sequence from the anode to the cathode, wherein at least one of the multiple layers contains the compound represented by general formula (1).

[0040] Similarly, in the above-mentioned organic electroluminescent element, the electron transport region may also be one or more layers. When it is a single layer, the electron transport region includes any one of an electron injection layer, an electron transport layer, a buffer layer, and a hole blocking layer; when the electron transport region includes multiple layers, it includes any multiple layers of a hole blocking layer, a buffer layer, an electron transport layer, and an electron injection layer arranged in sequence from the anode to the cathode, wherein at least one of the multiple layers contains the compound represented by general formula (2).

[0041] In the organic electroluminescent element, the light-emitting layer is composed of at least one host matrix and one guest dopant. The specific host matrix and guest dopant types can be reasonably selected and matched from existing materials. In a preferred embodiment of the present application, the host matrix of the organic electroluminescent element is an anthracene compound represented by the general formula (3),

[0042]

[0043] Among them, R 11 and R 12 are the same as or different from each other and are each independently hydrogen, a substituted or unsubstituted C1-C6 alkyl, alkoxy, C6-C30 aryl or heteroaryl; Ar4 and Ar5 are each independently selected from phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, naphthacene or pyrene; a, b, c are each an integer from 1 to 4. When a, b, c are each an integer of 2 or greater, the two or more structures in the brackets are the same as or different from each other.

[0044] In another preferred embodiment of the present application, in the above-mentioned organic electroluminescent element, the guest dopant of the light-emitting layer is a fluorescent dye represented by general formula (4),

[0045]

[0046] wherein Ar6 and Ar7 are the same or different and are each independently a substituted or unsubstituted silyl group, a C6-C30 aryl group or a heteroaryl group, or form a substituted or unsubstituted ring with each other; Ar8 is a substituted or unsubstituted benzofluorenyl group, a fluoranthene group, a pyrenyl group or a L5 is a direct bond, a substituted or unsubstituted C6-C18 arylene group or a heteroarylene group; n is an integer from 1 to 4, when n is an integer of 2 or greater, the two or more structures in the brackets are the same or different from each other.

[0047] There is no particular advantage requirement for the selection of the above-mentioned host and guest, as long as the application of blue fluorescence can be achieved. This application optimizes the combination of hole transport materials and electron transport materials. The compound shown in general formula (1) has good thermal stability and excellent hole transport ability. The compound shown in general formula (3) contains planar groups, phenanthrenyl, pyridyl and triazine electronegative groups. Such a molecular structure is not easy to crystallize due to large steric hindrance, and has improved thermal stability and excellent electron transport ability. Therefore, the combination of the two is more beneficial to the injection and transmission of holes and electrons on both sides, as well as balanced recombination in the light-emitting layer, thereby improving device efficiency.

[0048] It should be noted that the above-mentioned compounds used as electron transport regions in the present application can be arbitrarily combined with compounds used as hole transport regions, for example, any combination of any one of compounds 1-1 to 1-48 and any one of compounds 2-1 to 2-36 can be used. In a preferred embodiment, compounds 1-1, 1-4, 1-11, 1-18, 1-26, and 1-47 are arbitrarily combined with compounds 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-10, 2-11, 2-12, 2-13, 2-14, 2-15, 2-16, 2-17, 2-17, 2-18, 2-19, 2-20, 2-21, 2-22, 2-23, 2-24, 2-25, 2-26, 2-27, 2-28, 2-29, 2-30, 2-31, 2-32, 2-33, 2-34, 2-35, and 2-36.

[0049] The beneficial effects of the present application are further illustrated below with reference to specific embodiments.

[0050] Part 1:

[0051] 1. Preparation of hole transport layer materials

[0052] 1.1 Synthesis of Compound 1-1

[0053]

[0054] 9-(4'-chloro[1,1'-biphenyl]-2-yl)-9H-carbazole (21.2 g, 60 mmol), di-(4-biphenyl)amine (19.3 g, 60.6 mmol), 210 mL of toluene, and 8.48 g of sodium tert-butoxide were added to a 500 mL round-bottom flask. The temperature was raised to 50°C with stirring under nitrogen protection. 0.27 g of catalyst Pd2(dba)3 and 7.5 g of a 10% toluene solution of tri-tert-butylphosphine were added. The temperature was continued to rise to reflux for 4 h before the reaction was stopped. After cooling, 40 mL of water was added to separate the reaction. The organic phase was heated to reflux with toluene to remove water and dry, and then passed through a short silica gel column for decolorization. Half of the toluene was then rotary evaporated, the temperature was lowered to 70°C, 50 mL of n-hexane was added, the temperature was stirred and cooled, a solid precipitated, and filtered and dried to obtain 32.9 g of compound 1-1 as a white solid with a yield of 81.4%. Compound 1-1 was further purified twice by vacuum sublimation with a purity of 99.97% and MS [M+H] + = 638.25.

[0055] 1.2 Synthesis of Compounds 1-4

[0056]

[0057] 9-(4'-chloro[1,1'-biphenyl]-2-yl)-9H-carbazole (21.2 g, 60 mmol), N-(1,1-biphenyl)-1,1".4"-terphenyl)amine (24.1 g, 60.6 mmol), 210 mL of toluene, and 8.48 g of sodium tert-butoxide were added to a 500 mL round-bottom flask. The temperature was raised to 50°C with stirring under nitrogen protection. 0.27 g of catalyst Pd2(dba)3 and 7.5 g of a 10% toluene solution of tri-tert-butylphosphine were added. The temperature was continued to rise to reflux for 4 h before the reaction was stopped. After cooling, 40 mL of water was added to separate the reaction. The organic phase was heated to reflux with toluene to remove water and dry, and then passed through a short silica gel column for decolorization. Half of the toluene was then rotary evaporated, the temperature was lowered to 70°C, 50 mL of n-hexane was added, the temperature was stirred and cooled, a solid precipitated, and filtered to obtain 36.1 g of compound 1-4 as a white solid with a yield of 79.6%. Compound 1-4 was further purified twice by vacuum sublimation with a purity of 99.98% and MS [M+H] + = 714.34.

[0058] 1.3 Synthesis of Compound 1-11

[0059]

[0060] 9-(4'-chloro[1,1'-biphenyl]-2-yl)-9H-carbazole (21.2 g, 60 mmol), bis(9,9-dimethyl-9H-fluoren-2-yl)amine (24.3 g, 60.6 mmol), 210 mL of toluene, and 8.48 g of sodium tert-butoxide were added to a 500 mL round-bottom flask. The temperature was raised to 50°C with stirring under nitrogen protection. 0.27 g of catalyst Pd2(dba)3 and 7.5 g of a 10% toluene solution of tri-tert-butylphosphine were added. The temperature was continued to rise to reflux for 4 h before the reaction was stopped. After cooling, 40 mL of water was added to separate the reaction. The organic phase was heated to reflux with toluene to remove water and dry, and then passed through a short silica gel column for decolorization. Half of the toluene was then rotary evaporated, the temperature was lowered to 70°C, 50 mL of n-hexane was added, the temperature was stirred and cooled, a solid precipitated, and filtered and dried to obtain 35.7 g of compound 1-11 as a white solid with a yield of 78.5%. Compound 1-11 was further purified twice by vacuum sublimation with a purity of 99.97% and MS [M+H] + = 718.37.

[0061] 1.4 Synthesis of Intermediate A1

[0062]

[0063] To a 500 mL two-necked flask, 11H-benzo[c]carbazole (13.2 g, 60 mmol), copper iodide (11.4 g, 60 mmol), and potassium carbonate (16.6 g, 120 mmol) were added. 4-Chloro-4'-iodo-1,1'-biphenyl (37.7 g, 120 mmol) and 200 mL of xylene were then added under nitrogen. The reaction was stirred at 185°C for 72 hours. After the reaction was complete, the mixture was cooled and filtered to remove copper powder. The xylene was then removed by rotary evaporation under reduced pressure. The mixture was then purified by column chromatography to yield 31.2 g of white intermediate A1 in a 61.3% yield.

[0064] 1.5 Synthesis of Intermediate A2

[0065]

[0066] To a 500 mL two-necked flask, 5H-benzo[b]carbazole (13.2 g, 60 mmol), copper iodide (11.4 g, 60 mmol), and potassium carbonate (16.6 g, 120 mmol) were added. 4-Chloro-4'-iodo-1,1'-biphenyl (37.7 g, 120 mmol) and 200 mL of xylene were then added under nitrogen. The reaction was stirred at 185°C for 72 hours. After the reaction was complete, the mixture was cooled and filtered to remove copper powder. The xylene was then removed by rotary evaporation under reduced pressure. The mixture was then purified by column chromatography to yield 32.7 g of white intermediate A2 in a 64.2% yield.

[0067] 1.6 Synthesis of Intermediate A3

[0068]

[0069] To a 500 mL two-necked flask, 7H-benzo[c]carbazole (13.2 g, 60 mmol), copper iodide (11.4 g, 60 mmol), and potassium carbonate (16.6 g, 120 mmol) were added. 4-Chloro-4'-iodo-1,1'-biphenyl (37.7 g, 120 mmol) and 200 mL of xylene were then added under nitrogen. The reaction was stirred at 185°C for 72 hours. After the reaction was complete, the mixture was cooled and filtered to remove copper powder. The xylene was then removed by rotary evaporation under reduced pressure. The mixture was then purified by column chromatography to yield 32.3 g of white intermediate A3 in a 63.5% yield.

[0070] 1.7 Synthesis of Compound 1-18

[0071]

[0072] Intermediate A1 (24.2 g, 60 mmol), N-[1,1'-biphenyl]-4-yl-9,9-dimethyl-9H-fluoren-2-amine (21.9 g, 60.6 mmol), 210 mL of toluene, and 8.48 g of sodium tert-butoxide were added to a 500 mL round-bottom flask. The mixture was stirred and heated to 50°C under nitrogen protection. 0.27 g of catalyst Pd2(dba)3 and 7.5 g of a 10% toluene solution of tri-tert-butylphosphine were added. The temperature was continued to rise to reflux for 4 h before the reaction was stopped. After cooling, 40 mL of water was added to separate the reaction. The organic phase was heated to reflux with toluene to remove water and dried, and then passed through a short silica gel column for decolorization. Half of the toluene was then rotary evaporated, the temperature was cooled to 70°C, 50 mL of n-hexane was added, the temperature was stirred and cooled, a solid precipitated, and filtered and dried to obtain 35.6 g of compound 1-18 as a white solid with a yield of 77.2%. Compound 1-18 was further purified twice by vacuum sublimation with a purity of 99.99% and MS [M+H] + = 728.36.

[0073] 1.8 Synthesis of Compound 1-26

[0074]

[0075] Intermediate A2 (24.2 g, 60 mmol), di([1,1'-biphenyl]-3-yl)amine (19.5 g, 60.6 mmol), 210 mL of toluene, and 8.48 g of sodium tert-butoxide were added to a 500 mL round-bottom flask. The temperature was raised to 50°C with stirring under nitrogen protection. 0.27 g of catalyst Pd2(dba)3 and 7.5 g of a 10% toluene solution of tri-tert-butylphosphine were added. The temperature was continued to rise to reflux for 4 h before the reaction was stopped. After cooling, 40 mL of water was added to separate the mixture. The organic phase was heated to reflux with toluene to remove water and dry, and then passed through a short silica gel column for decolorization. Half of the toluene was then rotary evaporated, the temperature was lowered to 70°C, 50 mL of n-hexane was added, the temperature was stirred and cooled, a solid was precipitated, and the solid was filtered and dried to obtain 34.6 g of compound 1-26 as a white solid with a yield of 79.1%. Compound 1-18 was further purified twice by vacuum sublimation with a purity of 99.98%, MS [M+H] + = 688.28.

[0076] 1.9 Synthesis of Compound 1-47

[0077]

[0078] Intermediate A3 (24.2 g, 60 mmol), bis(9,9-dimethyl-9H-fluoren-2-yl)amine (24.3 g, 60.6 mmol), 210 mL of toluene, and 8.48 g of sodium tert-butoxide were added to a 500 mL round-bottom flask. The temperature was raised to 50° C. under nitrogen protection, and 0.27 g of catalyst Pd2(dba)3 and 7.5 g of a 10% toluene solution of tri-tert-butylphosphine were added. The temperature was continued to rise to reflux for 4 h before the reaction was stopped. After cooling, 40 mL of water was added to separate the two phases. The organic phase was heated to reflux with toluene to remove water and dry, and then passed through a short silica gel column for decolorization. Half of the toluene was then rotary evaporated, the temperature was lowered to 70° C., 50 mL of n-hexane was added, the temperature was stirred and cooled, a solid precipitated, and filtered to obtain 37.7 g of compound 1-47 as a white solid with a yield of 77.8%. Compound 1-47 was further purified twice by vacuum sublimation with a purity of 99.98%, MS [M+H] + = 768.42.

[0079] 2. Preparation of Electron Transport Layer Materials

[0080] 2.1 Synthesis of intermediate B

[0081]

[0082] 1-Bromo-2-iodobenzene (70.7 g, 250 mmol), phenylacetylene (25.5 g, 250 mmol) and 350 mL of triethylamine were added to a three-necked flask. After nitrogen protection for 10 minutes, CuI (0.48 g, 2.5 mmol) and 0.7 g of Pd(PPh3)2Cl2 were added. The reaction was stirred at room temperature for 0.5 hours and then stopped. A large amount of solid was obtained by filtration. The solid was rinsed with triethylamine and concentrated below 35°C to remove triethylamine. 100 mL of dichloromethane was added to dissolve the solid and washed with dilute hydrochloric acid solution until it was nearly neutral. The solid was then concentrated and dried to obtain 46.8 g of a yellow oil B1 with a yield of 96%.

[0083] B1 (15.4 g, 60 mmol), 4-chlorophenylboronic acid (10.3 g, 66 mmol), and potassium carbonate (16.6 g, 120 mmol) were added to a three-necked flask, followed by the addition of 90 mL of toluene, 45 mL of THF, and 45 mL of deionized water. After blowing nitrogen for 10 min, 0.31 g of Pd(PPh3)2Cl2 was added and heated to reflux. After reacting for 5 h, the mixture was cooled, separated, washed with water until neutral, concentrated by rotary evaporation, and then dissolved in ethanolamine phosphate. The mixture was passed through a silica gel column, eluted with ethanolamine phosphate, and concentrated by rotary evaporation to obtain 18.2 g of yellow oily liquid B2 with a yield of 71%.

[0084] B2 (14.5 g, 60 mmol) and 350 mL of dichloromethane were added to a three-necked flask, and the temperature was cooled to 0°C in an ice bath. 11.6 g of iodine chloride was dissolved in 90 mL of dichloromethane and added dropwise to the three-necked flask (dropwise addition for 0.5 h). The reaction was stirred for 0.5 h, and sodium sulfite solution was added dropwise to quench the reaction until neutral. The mixture was separated, dried, and concentrated by rotary evaporation. The mixture was passed through a silica gel column with phosphoethanolamine, concentrated by rotary evaporation, and dried to obtain 15.6 g of a light yellow-green solid B3 with a yield of 54%.

[0085] B3 (17.3g, 35mmol), 3-pyridine boric acid pinacol ester (10.9g, 53mmol), salt of wormwood (14.5g, 105mmol) are joined in there-necked flask, then add 105mL toluene, 35mL ethanol and 35mL deionized water, behind nitrogen protection 10min, add 0.87g Pd (PPh ) 2Cl , reflux, reaction 6h postcooling, separatory, washing, separate out solid, filter, be washed to neutrality, washing with ethanol, oven dry.200mL toluene is hot-melt, crosses silica gel column while hot, dichloromethane drip washing, and rotary evaporation is concentrated to about 50mL, cooling crystallization, oven dry obtains 10.7g faint yellow solid B, productive rate 38%.

[0086] 2.2 Synthesis of Intermediate C

[0087]

[0088] Intermediate B (18.3g, 50mmol), pinacol borate (15.2g, 60mmol), potassium acetate (14.7g, 150mmol) and 180mL dioxane are put into a 500ml round-bottom flask and stirred while heating. Pd (dba) 2 (0.57g, 1mmol) and tricyclohexylphosphine (0.56g, 2mmol) are added under reflux and stirred for 6 hours. After cooling to room temperature, 50ml water is added and stirred. The organic layer is separated and dried over anhydrous magnesium sulfate, then concentrated by rotary evaporation, and purified by silica gel column to obtain 21.8g intermediate C in a yield of 65%.

[0089] 2.3 Synthesis of compound 2-3

[0090]

[0091] C (11.7 g, 25 mmol), 2-bromo-4,6-diphenyl-1,3,5-triazine (7.8 g, 25 mmol), potassium carbonate (13.8 g, 100 mmol), tetrakis(triphenylphosphine)palladium (0.58 g, 0.5 mmol), 150 mL of tetrahydrofuran, and 75 mL of water were added to a 500 mL round-bottom flask, stirred and refluxed for 8 h, cooled to room temperature, and the organic layer was separated, then concentrated by rotary evaporation and purified on a silica gel column to give 20.1 g of the white solid product 2-3 in a 68% yield. Product 2-3 was further purified twice by vacuum sublimation to a purity of 99.96%, with MS [M+H] + = 562.32.

[0092] 2.4 Synthesis of Compound 2-9

[0093]

[0094] B (7.3 g, 20 mmol), (3-(4,6-diphenyl-1,3,5-triazine-2-)phenyl)boronic acid (7.4 g, 21 mmol), and potassium carbonate (8.3 g, 60 mmol) were added to a three-necked flask. 70 mL of toluene, 35 mL of THF, and 35 mL of deionized water were then added. After nitrogen purging for 10 min, 0.22 g of Pd(OAc)2 and 0.44 g of X-phos were added. The mixture was heated to 78°C for 1 h. A large amount of solid precipitated, which was filtered while hot, washed with water until nearly neutral, washed with ethanol, and dried. The solid was then dissolved in 150 mL of dichloromethane under reflux, passed through silica gel, and rinsed with dichloromethane. The solution was concentrated to approximately 50 mL, stirred at room temperature for crystallization, filtered, and rinsed with dichloromethane. The filter cake was recrystallized from 150 mL of dichloromethane to obtain 3.4 g of product 2-9 as a white solid in a 23% yield. The product 2-9 was further purified twice by vacuum sublimation with a purity of 99.96%, MS [M+H] + = 638.16.

[0095] 2. Thermodynamic properties of compounds

[0096] The glass transition temperature Tg was determined by differential scanning calorimetry (DSC, DSC25 differential scanning calorimeter from TA Instruments, USA) at a heating rate of 10°C / min; the decomposition temperature Td was the temperature at which the weight loss was 1% in a nitrogen atmosphere, and was determined on a TGA55 thermogravimetric analyzer from TA Instruments, USA, with a nitrogen flow rate of 20 mL / min. Specific data are shown in Table 1 below.

[0097] Table 1:

[0098] Compound Tg(℃) Td(℃) 1-1 116 382 1-4 119 389 1-11 125 396 1-18 131 405 1-26 122 391 1-47 134 411 2-3 139 350 2-9 145 366

[0099] As can be seen from the data in the table, the glass transition temperatures of the compounds represented by general formula (1) and (2) used in the present invention are both above 100° C., are not easily decomposed, and have excellent thermal stability.

[0100] Part II: Preparation of organic electroluminescent elements

[0101] The following describes in detail the actual effects of the organic electroluminescent element prepared by combining the compound represented by general formula (1) as the material of the hole transport region and the compound represented by general formula (2) as the material of the electron transport region through specific examples and comparative examples.

[0102] The structural formula of the organic materials used is as follows:

[0103]

[0104]

[0105] Example 1

[0106] The organic electroluminescent element was manufactured using a Sunic sp1710 evaporation machine. The specific steps were as follows: a glass substrate (Corning glass 40mm*40mm*0.7mm) coated with ITO (indium tin oxide) with a thickness of 135nm was ultrasonically cleaned with isopropyl alcohol and pure water for 5 minutes respectively, and then cleaned with ultraviolet ozone. After that, the glass substrate was transferred to a vacuum deposition chamber; a hole transport material HT1 doped with 4% HD was vacuum-deposited with a thickness of 20nm (about 10 -7 Torr) was thermally deposited on a transparent ITO electrode to form a hole injection layer; a 60nm thick compound 1-1 was then vacuum deposited on the hole injection layer as a first hole transport layer; a second hole transport layer HT2 was then vacuum deposited; a 25nm layer of BH doped with 4% BD by mass was then vacuum deposited as a light-emitting layer; a compound 2-3 doped with 50% LiQ (8-hydroxyquinoline lithium) was then vacuum deposited to form an electron transport layer with a thickness of 30nm; finally, a 2nm thick metal ytterbium (Yb, electron injection layer) and a magnesium-silver alloy doped with a ratio of 10:1 were sequentially deposited to form a cathode; the component was finally transferred from the deposition chamber to a glove box and then encapsulated with a UV-curable epoxy resin and a glass cover containing a desiccant.

[0107] In the above manufacturing steps, the deposition rates of the organic material, metal ytterbium, and metal Mg were maintained at 0.1 nm / s, 0.05 nm / s, and 0.2 nm / s, respectively.

[0108] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-1 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0109] Example 2

[0110] The experiment was performed in the same manner as in Example 1, except that Compound 1-4 was used as the first hole transport layer.

[0111] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-4 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0112] Example 3

[0113] The experiment was performed in the same manner as in Example 1, except that Compound 1-11 was used as the first hole transport layer.

[0114] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-11 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0115] Example 4

[0116] The experiment was performed in the same manner as in Example 1, except that Compound 1-18 was used as the first hole transport layer.

[0117] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-18 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0118] Example 5

[0119] The experiment was performed in the same manner as in Example 1, except that Compound 1-26 was used as the first hole transport layer.

[0120] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-26 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0121] Example 6

[0122] The experiment was performed in the same manner as in Example 1, except that Compound 1-47 was used as the first hole transport layer.

[0123] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-47 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0124] Example 7

[0125] The experiment was performed in the same manner as in Example 1, except that Compound 1-11 was used as the first hole transport layer, and Compound 2-9 was used as the electron transport layer.

[0126] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-11 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-9:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0127] Example 8

[0128] The experiment was performed in the same manner as in Example 1, except that Compound 1-18 was used as the first hole transport layer, and Compound 2-9 was used as the electron transport layer.

[0129] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-18 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-9:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0130] Example 9

[0131] The experiment was performed in the same manner as in Example 1, except that Compound 1-26 was used as the first hole transport layer and Compound 2-9 was used as the electron transport layer.

[0132] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-26 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-9:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0133] Example 10

[0134] The experiment was performed in the same manner as in Example 1, except that Compound 1-47 was used as the first hole transport layer and Compound 2-9 was used as the electron transport layer.

[0135] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-47 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / Compound 2-9:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0136] Example 11

[0137] The experiment was performed in the same manner as in Example 1, except that Compound 1-4 was used as the first hole transport layer, and Compound 1-11 was used instead of HT2 as the second hole transport layer.

[0138] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-4 (60nm) / Compound 1-11 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0139] Example 12

[0140] The experiment was performed in the same manner as in Example 1, except that Compound 1-4 was used as the first hole transport layer, and Compound 1-18 was used instead of HT2 as the second hole transport layer.

[0141] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-4 (60nm) / Compound 1-18 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0142] Example 13

[0143] The experiment was performed in the same manner as in Example 1, except that Compound 1-4 was used as the first hole transport layer, and Compound 1-47 was used instead of HT2 as the second hole transport layer.

[0144] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / Compound 1-4 (60nm) / Compound 1-47 (10nm) / BH:4%BD (25nm) / Compound 2-3:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0145] Example 14

[0146] The experiment was conducted in the same manner as in Example 1, except that Compound 1-4 was used instead of HT1 as both the hole injection layer host and the first hole transport layer, and Compound 1-11 was used instead of HT2 as the second hole transport layer.

[0147] The device structure is represented as: ITO (135nm) / Compound 1-4: 4% HD (20nm) / Compound 1-4 (60nm) / Compound 1-11 (10nm) / BH: 4% BD (25nm) / Compound 2-3: LiQ (5:5, 30nm) Yb (2nm) / Mg:Ag (10:1, 150nm).

[0148] Example 15

[0149] The experiment was conducted in the same manner as in Example 1, except that Compound 1-4 was used instead of HT1 as both the hole injection layer host and the first hole transport layer, and Compound 1-18 was used instead of HT2 as the second hole transport layer.

[0150] The device structure is represented as: ITO (135nm) / Compound 1-4: 4% HD (20nm) / Compound 1-4 (60nm) / Compound 1-18 (10nm) / BH: 4% BD (25nm) / Compound 2-3: LiQ (5:5, 30nm) Yb (2nm) / Mg:Ag (10:1, 150nm).

[0151] Comparative Example 1

[0152] The experiment was performed in the same manner as in Example 1, except that Compound HT1 was used instead of Compound 1-1 as the first hole transport layer, and Compound ET was used instead of Compound 2-3 as the electron transport layer.

[0153] The device structure is represented as: ITO (135nm) / HT1:4%HD (20nm) / HT1 (60nm) / HT2 (10nm) / BH:4%BD (25nm) / ET:LiQ (5:5, 30nm)Yb (2nm) / Mg:Ag (10:1, 150nm).

[0154] The brightness, luminous efficiency, and EQE (external quantum efficiency) of the light-emitting element were tested by Suzhou Fushida FS-100GA4. The device life LT95 (the time it takes for the initial brightness to decay from 4000 nits to 3800 nits) was tested by Fushida FS-MP96. All measurements were completed in room temperature and atmosphere. 2 The specific performance data of the operating voltage (V), current efficiency (CE), external quantum efficiency (EQE) and color coordinates (CIEx, CIEy) under current density are shown in Table 2.

[0155] Table 2:

[0156]

[0157]

[0158] As can be seen from the table, the above-mentioned embodiments of the present invention achieve the following technical effects: Compared with Comparative Example 1, the device driving voltage of Examples 1 to 15 is reduced, the efficiency is improved, and the lifespan is significantly increased. This shows that the compound represented by general formula (1) as the first hole transport layer increases the hole transmission rate, and the compound represented by general formula (2) as the electron transport layer also increases the electron transmission rate. The combination of the two promotes the effective recombination of holes and electrons, thereby improving device efficiency. In addition, due to the excellent thermal stability of both, the device lifespan is also improved.

[0159] On this basis, Examples 11 to 13 simultaneously use the compound represented by general formula (1) as the second hole transport layer, optimize the interface between the first hole transport layer and the second hole transport layer, and the efficiency and life of the device are improved compared with Example 2. On the basis of Examples 11 and 12, Examples 14 and 15 further use the compound represented by general formula (1) as the hole injection layer, optimize the injection of holes, and thus further improve the efficiency and life of the device.

[0160] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An organic electroluminescent element comprising a hole transport region, a light-emitting layer, and an electron transport region arranged in sequence from an anode to a cathode, characterized in that: The hole transport region contains a compound represented by the general formula (1), and the electron transport region contains a compound represented by the general formula (2): In the general formula (1), R1 to R8 are the same as or different from each other, and are each independently hydrogen, deuterium, a substituted or unsubstituted C1-C4 alkyl group, a C6-C30 aryl group, or optionally combined with adjacent groups to form a substituted or unsubstituted ring; Ar1 and Ar2 are the same as or different from each other and are each independently a substituted or unsubstituted C6-C30 aryl group, L1 to L3 are the same as or different from each other, and are each independently a direct bond, or a substituted or unsubstituted C6-C18 arylene group; In general formula (2), Py is an unsubstituted pyridyl group; R9 is selected from hydrogen, C1-C4 alkyl, or substituted or unsubstituted C6-C18 aryl; Ar3 is selected from substituted or unsubstituted C6-C18 aryl or heteroaryl; L4 is selected from a direct bond or an unsubstituted phenylene group; At least one of Z1 to Z3 is N, and the others are CH.

2. The organic electroluminescent element according to claim 1, wherein The compound represented by the general formula (1) is represented by any one of the following general formulas (1-A), (1-B) and (1-C): In the general formulae (1-A), (1-B) and (1-C), R1 to R8, Ar1 and Ar2, and L1 to L3 are the same as defined in the general formula (1).

3. The organic electroluminescent element according to claim 2, wherein In the compounds represented by the general formulae (1-A), (1-B) and (1-C), R1 to R8 are all H, L3 is a direct bond, L1 and L2 are direct bonds, and Ar1 and Ar2 are unsubstituted C6-C25 aromatic groups.

4. The organic electroluminescent element according to claim 3, wherein The unsubstituted C6-C25 aryl group is biphenyl, terphenyl, naphthalene or anthracene.

5. The organic electroluminescent element according to claim 4, wherein The biphenyl is o-biphenyl, m-biphenyl or p-biphenyl.

6. The organic electroluminescent element according to claim 1, wherein In the compound represented by the general formula (1), R1 to R8 are all H, L3 is a direct bond, L1 and L2 are direct bonds, and Ar1 and Ar2 are unsubstituted C6-C25 aryl groups.

7. The organic electroluminescent element according to claim 6, wherein: The unsubstituted C6-C25 aryl group is biphenyl, terphenyl, naphthalene or anthracene.

8. The organic electroluminescent element according to claim 7, wherein The biphenyl is o-biphenyl, m-biphenyl or p-biphenyl.

9. The organic electroluminescent element according to claim 1, wherein The compound represented by the general formula (1) is selected from any one of the following:

10. The organic electroluminescent element according to claim 1, wherein In the nitrogen-containing heterocyclic compound represented by the general formula (2), Py is a pyridyl group, R is a phenyl group, Ar3 is a phenyl group or a naphthyl group, and L is a phenylene group.

11. The organic electroluminescent element according to claim 10, wherein The compound represented by the general formula (2) is selected from any one of the following:

12. The organic electroluminescent element according to claim 1, wherein The hole transport region includes any one of a hole injection layer, a hole transport layer, a buffer layer and an electron blocking layer; or the hole transport region includes any multiple layers of a hole injection layer, a hole transport layer, a buffer layer and an electron blocking layer arranged in sequence from the anode to the cathode, wherein at least one layer of the any multiple layers contains the compound represented by the general formula (1).

13. The organic electroluminescent element according to claim 1, wherein The electron transport region includes any one of an electron injection layer, an electron transport layer, a buffer layer and a hole blocking layer; or the electron transport region includes any multiple layers of a hole blocking layer, a buffer layer, an electron transport layer and an electron injection layer arranged in sequence from the anode to the cathode, and at least one layer of the any multiple layers contains the compound represented by the general formula (2).

14. The organic electroluminescent element according to any one of claims 1 to 13, characterized in that: The light-emitting layer is composed of at least a host matrix and a guest dopant mixed together.

15. The organic electroluminescent element according to claim 14, wherein The main matrix is ​​an anthracene compound represented by general formula (3), Among them, R 11 and R 12 are the same as or different from each other and are each independently hydrogen, a substituted or unsubstituted C1-C6 alkyl, alkoxy, C6-C30 aryl or heteroaryl; Ar4 and Ar5 are each independently selected from phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, naphthacene or pyrene; a, b, c are each an integer of 1 to 4. When a, b, c are each an integer of 2 or greater, two or more structures in the brackets are the same as or different from each other.

16. The organic electroluminescent element according to claim 14, wherein The guest dopant of the light-emitting layer is a fluorescent dye represented by the general formula (4), wherein Ar6 and Ar7 are the same as or different from each other and are each independently a substituted or unsubstituted silyl group, a C6-C30 aryl group or a heteroaryl group, or form a substituted or unsubstituted ring together; Ar8 is a substituted or unsubstituted benzofluorenyl, fluoranthenyl, pyrenyl or base; L5 is a direct bond, a substituted or unsubstituted C6-C18 arylene group or a heteroarylene group; n is an integer of 1 to 4, and when n is an integer of 2 or greater, two or more structures in the brackets are the same as or different from each other.

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