Organic electroluminescent elements

Abstract

This invention provides an organic electroluminescent element. The organic electroluminescent element includes a hole-assisted layer and an electron transport layer. The hole-assisted layer contains one or more compounds of formula (I); the electron transport layer contains one or more compounds of formula (II). The organic electroluminescent element using this combination of materials achieves both high device efficiency and low driving voltage, resulting in superior overall performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic electroluminescent element. Specifically, it relates to an organic electroluminescent element. BACKGROUND

[0002] The organic electroluminescent element (OLED) has the characteristics of light and thin, wide viewing angle, high contrast, low power consumption, high response speed, full-color picture and flexibility, etc., and has been applied in the fields of smart phones, tablet computers and vehicle-mounted devices, and is expanding to the field of large-size applications such as television.

[0003] The organic electroluminescent element generally includes a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and the like. The glass transition temperature of the film layer, the energy level matching between the film layers, the film formation quality and stability of the film layer and the like will affect the performance of the element. Among them, the hole transport layer and the electron transport layer are key material layers, the selection of the material will affect the transmission rate of the hole and the electron, the matching degree of the two will further affect the combination efficiency of the electron and the hole in the light-emitting layer, in addition, the stability of the material will ultimately determine the good or bad of the device performance. Therefore, how to select the appropriate material collocation is very important to further improve the comprehensive performance of the device. SUMMARY

[0004] The main purpose of the present application is to provide an organic electroluminescent element, so as to further reduce the driving voltage of the organic electroluminescent element and improve the element efficiency.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an organic electroluminescent element is provided, which comprises a hole auxiliary layer and an electron transport layer, the hole auxiliary layer contains one or more of the compounds represented by formula (I), and the electron transport layer contains one or more of the compounds represented by formula (II):

[0006]

[0007] In formula (I), Ar1(Ar2)N- is selected from the following groups:

[0008]

[0009] Ar3, Ar4 are each independently selected from the following structures:

[0010]

[0011] In the above-mentioned groups, the dotted line represents the connecting site bonded to nitrogen; R1 is each independently selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, cycloheptyl, n-octyl, phenyl or 4-tert-butylphenyl;

[0012] provided that Ar1(Ar2)N- and -NAr3(Ar4) are different;

[0013] In formula (II), at least one of X1 to X3 is N;

[0014] Ar5 and Ar6 are the same or different from each other, and each is independently selected from a substituted or unsubstituted C6-C 30 aryl group; and a substituted or unsubstituted C6-C 30 heteroaryl group.

[0015] By applying the technical solution of the present application, the compound represented by formula (I) is used in the hole auxiliary layer in the organic electroluminescent element provided in the present application the compound represented by formula (II) is used in the electron transport layer

[0016] The hole auxiliary layer can form a better match with the electron transport layer, so that the transport of holes and electrons can be balanced. Therefore, the organic electroluminescent element provided in the present application can have high efficiency and low driving voltage, and has more excellent comprehensive performance. BRIEF DESCRIPTION OF DRAWINGS

[0017] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the exemplary embodiments of the present application and their description, serve to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0018] Figure 1 A structural schematic diagram of an organic electroluminescent element according to an embodiment of the present application is shown;

[0019] Figure 2 A structural schematic diagram of an organic electroluminescent element according to another embodiment of the present application is shown;

[0020] Figure 3 A structural schematic diagram of an organic electroluminescent element according to still another embodiment of the present application is shown.

[0021] Among the above drawings, the following reference signs are included:

[0022] 110, substrate; 120, anode; 130, hole injection layer; 140, hole transport layer; 141, electron blocking layer; 150, light-emitting layer; 151, hole blocking layer; 160, electron transport layer; 170, electron injection layer; 180, cathode. DETAILED DESCRIPTION

[0023] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0024] As described in the background section, the material matching between the hole auxiliary layer and the electron transport layer in the prior art affects the performance of the organic electroluminescent element.

[0025] To solve the above problems, the present application provides an organic electroluminescent element, which comprises a hole auxiliary layer and an electron transport layer 160, the hole auxiliary layer contains one or more of the compounds represented by formula (I), and the electron transport layer 160 contains one or more of the compounds represented by formula (II):

[0026]

[0027] In formula (I), Ar1(Ar2)N- includes but is not limited to the following groups:

[0028]

[0029] Ar3, Ar4 each independently includes but is not limited to the following structures:

[0030]

[0031]

[0032] In the above groups, the dotted line represents the connecting site bonded to nitrogen; R1 each independently includes but is not limited to methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, cycloheptyl, n-octyl, phenyl or 4-tert-butylphenyl;

[0033] Provided that Ar1(Ar2)N- and -NAr3(Ar4) are different;

[0034] In formula (II), at least one of X1 to X3 is N;

[0035] Ar5 and Ar6 are the same or different from each other and each independently includes but is not limited to a substituted or unsubstituted C6-C 30 aryl group; a substituted or unsubstituted C6-C 30 heteroaryl group.

[0036] In the organic electroluminescent element provided by the present application, the compound represented by formula (I) is used in the hole auxiliary layer The compound represented by formula (II) is used in the electron transport layer 160

[0037] The hole auxiliary layer can form a better match with the electron transport layer 160, so that the transport of holes and electrons can be balanced. Therefore, the organic electroluminescent element provided by the present application can have high element efficiency and low driving voltage, and has more excellent comprehensive performance.

[0038] Exemplarily, the compound represented by formula (I) includes but is not limited to the following structures:

[0039]

[0040]

[0041]

[0042]

[0043] Exemplarily, the compound represented by formula (II) includes but is not limited to the following structures:

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050] The chemical structure of the above-mentioned hole auxiliary layer can adopt a structure commonly used in the art. For example, the hole auxiliary layer includes at least two layers stacked in sequence, as long as at least one layer contains the compound represented by formula (I), the comprehensive performance of the organic electroluminescent element in terms of efficiency, service life and driving voltage can be effectively improved.

[0051] In a preferred embodiment, the organic electroluminescent element includes an anode 120, a hole auxiliary layer, a light-emitting layer 150, an electron auxiliary layer and a cathode 180 stacked in sequence; the hole auxiliary layer includes a first hole auxiliary layer, a second hole auxiliary layer and a third hole auxiliary layer stacked in sequence, the first hole auxiliary layer is in contact with the anode 120, and the third hole auxiliary layer is in contact with the light-emitting layer 150; wherein the first hole auxiliary layer and the second hole auxiliary layer both contain the compound represented by formula (I), and the first hole auxiliary layer further contains a P-type doped compound. By using the above-mentioned structure, the compound represented by formula (I) is used in the first hole auxiliary layer and the second hole auxiliary layer, and the comprehensive performance of the element is better.

[0052] Specifically, in an embodiment, asFigure 1 As shown in the above structure, the organic electroluminescent element comprises a substrate 110, an anode 120, a hole auxiliary layer, a light-emitting layer 150, an electron auxiliary layer and a cathode 180 which are sequentially stacked; wherein the hole auxiliary layer comprises a hole injection layer 130 and a hole transport layer 140 which are sequentially stacked, and the material of at least one of the two layers contains the compound shown in the above formula (I), and the hole injection layer 130 further contains a P-type doped compound. The electron auxiliary layer comprises an electron transport layer 160 and an electron injection layer 170 which are sequentially stacked.

[0053] In another embodiment, as shown in the above structure, the organic electroluminescent element comprises a substrate 110, an anode 120, a hole auxiliary layer, a light-emitting layer 150, an electron auxiliary layer and a cathode 180 which are sequentially stacked; wherein the hole auxiliary layer comprises a hole injection layer 130, a hole transport layer 140 and an electron blocking layer 141 which are sequentially stacked, and the material of at least one of the three layers contains the compound shown in the above formula (I), and the hole injection layer 130 further contains a P-type doped compound. The electron auxiliary layer comprises an electron transport layer 160 and an electron injection layer 170 which are sequentially stacked. Figure 2 In yet another embodiment, as shown in the above structure, the organic electroluminescent element comprises a substrate 110, an anode 120, a hole auxiliary layer, a light-emitting layer 150, an electron auxiliary layer and a cathode 180 which are sequentially stacked; wherein the hole auxiliary layer comprises a hole injection layer 130 and a hole transport layer 140 which are sequentially stacked, and the material of at least one of the two layers contains the compound shown in the above formula (I), and the hole injection layer 130 further contains a P-type doped compound. The electron auxiliary layer comprises a hole blocking layer 151, an electron transport layer 160 and an electron injection layer 170 which are sequentially stacked.

[0054] Figure 3 The organic electroluminescent element of the above structure shown in the above figure can be top emission or bottom emission, and one or more layers can be added or removed as needed in the top emission structure.

[0055] Preferably, the first hole auxiliary layer is a hole injection layer 130, the second hole auxiliary layer is a hole transport layer 140, and the third hole auxiliary layer is an electron blocking layer 141. The hole auxiliary layer of the above structure can better match the electron auxiliary layer, thereby further improving the overall performance of the element. More preferably, the material of the first hole auxiliary layer comprises the compound shown in formula (I) and a P-type doped compound, and the doping amount of the P-type doped compound is 4-20 wt%.

[0056] The P-type doped compound can include but is not limited to bismuth telluride, cadmium sulfide, cadmium selenide, gallium nitride, fulvene compound, titanium dioxide, zinc oxide or the compound shown in formula A:

[0057]

[0058] ​​

[0059] The P-doped compound is further preferably an acene compound, and more preferably a compound represented by formula (I) shown below.

[0060]

[0061] In one embodiment, the organic electroluminescent device has a structure as shown in FIG. 1. In this structure, the hole injection layer 130 and the hole transport layer 140 contain the compound represented by formula (I) shown above, and the thickness of the hole injection layer 130, the hole transport layer 140, and the electron blocking layer 141 is in the range of 20 to 100 nm, 80 to 200 nm, and 10 to 50 nm, respectively. Figure 2

[0062] Preferably, the light emitted from the light-emitting layer 150 is red, green, or blue. The materials of the other layers except for the hole auxiliary layer and the electron transport layer 160 can be the materials commonly used in the art, for example, the material of the light-emitting layer 150 can be a fluorescent material, and preferably includes a host material and a dopant material. The host material is an aromatic condensed ring derivative or a heterocyclic compound, etc.

[0063] 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, diphenyl furan derivatives, pyrimidine derivatives, triazine derivatives, etc., but not limited thereto.

[0064] Specifically, as the dopant material, there are aromatic amine derivatives, styryl amine compounds, boron complexes, fluoranthene compounds, metal complexes, etc. Specifically, as the aromatic amine derivative, it is an aromatic condensed ring derivative having a substituted or unsubstituted arylamino group, and there are pyrene, anthracene, diindenopyrene, etc., having an arylamino group; as the styryl amine compound, it is a compound having at least one arylvinyl group substituted on a substituted or unsubstituted arylamine, and is substituted or unsubstituted by one or two or more substituents included in but not limited to aryl, silyl, alkyl, cycloalkyl, and arylamino. Specifically, there are styryl amine, styryl diamine, styryl triamine, styryl tetraamine, etc., but not limited thereto. In addition, as the metal complex, there are iridium complexes, platinum complexes, etc., but not limited thereto.

[0065] ​As the anode material, a material having a large work function is preferable in order to enable holes to be injected into the organic layer smoothly. Examples of the anode material include 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 combinations of metals and oxides such as ZnO:Al; conductive high molecular weight polymers such as poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDOT), polypyrrole, and polyaniline, but are not limited thereto.

[0066] As the cathode material, a material having a small work function is preferable in order to enable electrons to be injected into the organic layer easily. Examples of the cathode material include metals such as magnesium, calcium, indium, lithium, aluminum, silver, tin, and lead, and alloys thereof; multilayered materials such as Mg:Ag and LiF / Al, but are not limited thereto.

[0067] The advantageous effects of the present application will be described below with reference to specific examples and comparative examples.

[0068] 1. Synthesis of hole auxiliary layer material

[0069] 1.1 Synthesis of intermediate D1

[0070] The synthesis route of intermediate D1 is as follows:

[0071]

[0072] To 2-bromo-2'-chlorospirobifluorene 43 g (100 mmol) and N-[1,1'-biphenyl]-2-yl-9,9-dimethyl-9H-fluoren-2-amine 38 g (105 mmol), dry and degassed toluene was added as solvent, 13 g (135 mmol) of sodium tert-butoxide (t-BuONa), 1.76 g (1.92 mmol) of catalyst tris(dibenzylideneacetone)dipalladium Pd2(dba)3, 2.13 g (3.84 mmol) of 1,1'-bis(diphenylphosphino)ferrocene DPPF ligand were added and warmed to 100-105°C for 4 h. After the reaction was completed, it was cooled to room temperature, diluted with toluene, filtered through silica gel, and the filtrate was evaporated under vacuum to obtain a crude product. The crude product was recrystallized after being dissolved in toluene and decolorized to obtain 60 g of intermediate D1 at a yield of 85%.

[0073] The results of the characterization of intermediate D1 are as follows:

[0074] 1HNMR (CDC13, 400 MHz) δ 8.14-8.06 (m, 1H), 7.94-7.81 (m, 6H), 7.75 (dd, J = 14.7, 3.2 Hz, 2H), 7.69-7.33 (m, 15H), 7.33-6.94 (m, 18H), 6.50 (d, J = 2.9 Hz, 1H), 6.19 (d, J = 15.0 Hz, 1H), 1.69 (s, 6H).

[0075] 1.2 Synthesis of compound I-3

[0076] The synthesis route of compound I-3 is as follows:

[0077]

[0078] Compound D132g (45 mmol) and N-phenyl-3-biphenylamine 12.1 g (49.5 mmol) were added, and dry and degassed toluene was added as solvent, 6.5 g (67.5 mmol) of sodium tert-butoxide, 0.88 g (0.96 mmol) of catalyst Pd2(dba)3 was added, and the temperature was raised to 80°C, 4.5 mL of 10% mass concentration of tri-tert-butylphosphine toluene solution was slowly added dropwise, and after the dropwise addition was completed, the temperature was raised to 100-105°C, and the reaction was carried out for 6 h. After the reaction was completed, it was cooled to room temperature, diluted with toluene, filtered with silica gel, and the filtrate was evaporated under vacuum to obtain a crude product, which was dissolved in xylene, decolorized and recrystallized to obtain 29.9 g of product I-3, with a yield of 67.8%. Further purification was carried out by vacuum sublimation, and the purity was 99.75%.

[0079] The characterization results of compound I-3 are as follows:

[0080] 1 HNMR (CDC13, 400 MHz) δ 8.14-8.06 (m, 1H), 7.94-7.81 (m, 6H), 7.75 (dd, J = 14.7, 3.2 Hz, 2H), 7.69-7.33 (m, 15H), 7.33-6.94 (m, 18H), 6.50 (d, J = 2.9 Hz, 1H), 6.19 (d, J = 15.0 Hz, 1H), 1.69 (s, 6H).

[0081] 1.3 Synthesis of compound I-7

[0082] The synthesis route of compound I-7 is as follows:

[0083]

[0084] The same as the synthesis method of compound I-3, except that bis(4-biphenyl)amine was used instead of N-phenyl-3-biphenylamine, with a yield of 53.1% and a purity of 99.84%.

[0085] The characterization results of compound I-7 are as follows:

[0086] 1 HNMR (CDCI3, 400 MHz) δ 7.90-7.84 (m, 7H), 7.74 (d, J = 7.5 Hz, 4H), 7.54 (d, J = 7.5 Hz, 6H), 7.48 (t, J = 7.5 Hz, 4H), 7.46-7.36 (m, 14H), 7.34-7.26 (m, 6H), 7.22 (s, 1H), 7.15 (m, 3H), 7.07 (d, J = 7.5 Hz, 3H), 1.68 (s, 6H).

[0087] 1.4 Synthesis of compound I-19

[0088] The synthesis route of compound I-19 is as follows:

[0089]

[0090] The same as the synthesis method of compound I-3, except that N-phenyl-4-dibenzofuran amine is used to replace di(4-biphenyl)amine, the yield is 45%, and the purity is 99.75%.

[0091] The characterization results of compound I-19 are as follows:

[0092] 1 HNMR (CDCI3, 400 MHz) δ 7.90-7.84 (m, 7H), 7.74 (d, J = 7.5 Hz, 4H), 7.54 (d, J = 7.5 Hz, 6H), 7.48 (t, J = 7.5 Hz, 4H), 7.46-7.36 (m, 14H), 7.34-7.26 (m, 6H), 7.22 (s, 1H), 7.15 (m, 3H), 7.07 (d, J = 7.5 Hz, 3H), 1.68 (s, 6H).

[0093] 2. Synthesis of electron transport layer material

[0094] 2.1 Synthesis of intermediate M1

[0095] The synthesis route of intermediate M1 is as follows:

[0096]

[0097] Compound Ml (72.26 g, 272.61 mmol), bis(pinacolato)diboron (83.08 g, 327.13 mmol), 550 mL of toluene, potassium acetate (53.51 g, 545.22 mmol) were added into a 1000 mL round bottom flask, stirred under nitrogen protection, heated to 50 °C, added 2.49 g of catalyst Pd2(dba)3and 2.6 g of 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl, continued to heat to reflux, reacted for 3 h, then stopped the reaction, the organic phase was decolorized with alumina silica gel short column while hot, then rotary evaporation, cooled, added 575 mL of ethanol, heated to 80 °C, stirred and cooled to precipitate solid, filtered and dried to obtain 92.16 g of white intermediate M2, yield 94.7%, purity 99.95%.

[0098] 2.2 Synthesis of intermediate M2

[0099] The synthesis route of intermediate M2 is as follows:

[0100]

[0101] Compound Ml (72.26 g, 272.61 mmol), bis(pinacolato)diboron (83.08 g, 327.13 mmol), 550 mL of toluene, potassium acetate (53.51 g, 545.22 mmol) were added into a 1000 mL round bottom flask, stirred under nitrogen protection, heated to 50 °C, added 2.49 g of catalyst Pd2(dba)3and 2.6 g of 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl, continued to heat to reflux, reacted for 3 h, then stopped the reaction, the organic phase was decolorized with alumina silica gel short column while hot, then rotary evaporation, cooled, added 575 mL of ethanol, heated to 80 °C, stirred and cooled to precipitate solid, filtered and dried to obtain 92.16 g of white intermediate M2, yield 94.7%, purity 99.95%.

[0102] 2.3 Synthesis of intermediate M3

[0103] The synthesis route of intermediate M3 is as follows:

[0104]

[0105] Into a 1000 mL round bottom flask, 1-bromo-3-chlorodibenzo[b,d]furan (33.78 g, 120 mmol), compound M2 (45.01 g, 126 mmol), 360 mL of toluene, potassium carbonate (49.86 g, 360 mmol), 180 mL of water, 180 mL of ethanol were added, and the mixture was stirred under nitrogen protection and heated to 50°C. 0.84 g of catalyst PdCl2(PPh3)2was added, and the reaction was continued to reflux for 6.5 h. After the reaction was stopped, the mixture was allowed to cool, and the organic phase was decolorized on a short column of alumina silica gel after heating the toluene. Then, the toluene was removed by rotary evaporation until about 110 mL remained. The mixture was heated to 80°C until it was completely dissolved, 85 mL of ethanol was added, and the mixture was allowed to cool and the solid was filtered and dried to obtain 32.2 g of white intermediate M3, with a yield of 62.13% and a purity of 99.4%.

[0106] 2.4 Synthesis of intermediate M4

[0107] The synthesis route of intermediate M4 is as follows:

[0108]

[0109] Into a 2000 mL round bottom flask, intermediate M3 (108.3 g, 250.74 mmol), bis(pinacolato)diboron (76.41 g, 300.89 mmol), 550 mL of toluene, potassium acetate (49.22 g, 501.48 mmol) were added, and the mixture was stirred under nitrogen protection and heated to 50°C. 2.29 g of catalyst Pd2(dba)3and 2.39 g of 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl were added, and the reaction was continued to reflux for 4.5 h. After the reaction was stopped, the organic phase was decolorized on a short column of alumina silica gel while hot, and then the toluene was removed by rotary evaporation. After cooling, 300 mL of n-hexane was added and heated to 80°C to make a slurry. The mixture was allowed to cool and the solid was filtered and dried to obtain 120 g of white intermediate M4, with a yield of 91.81% and a purity of 99.4%.

[0110] 2.5 Synthesis of intermediate M5

[0111] The synthesis route of intermediate M5 is as follows:

[0112]

[0113] Into a 2000 mL round bottom flask, 2,4,6-trichloropyrimidine (73 g, 400 mmol), 2-naphthaleneboronic acid (141 g, 820 mmol), 800 mL of toluene, sodium carbonate (127.2 g, 1200 mmol), 600 mL of water, 200 mL of ethanol were added, and the mixture was stirred under nitrogen protection and heated to 40 °C. Then 13.9 g of catalyst PdCl2(PPh3)2was added, and the reaction was continued to reflux for 11 h. The reaction was stopped, and the mixture was cooled and filtered. The filtrate was separated, and the organic phase was heated and passed through a short column of alumina silica gel to remove color. Then the toluene was evaporated to about 500 mL, and the mixture was heated to 80 °C until it was completely dissolved. Then 150 mL of isopropanol was added, and the mixture was cooled to precipitate the solid. The solid was filtered and dried to obtain 82 g of intermediate M5 with a yield of 56.16%. The intermediate M5 was further recrystallized once by the same method to obtain a purity of 99.8%.

[0114] 2.6 Synthesis of intermediate M6

[0115] The synthesis route of intermediate M6 is as follows:

[0116]

[0117] Into a 2000 mL round bottom flask, 2,4,6-trichloropyrimidine (73 g, 400 mmol), 2-naphthaleneboronic acid (141 g, 820 mmol), 800 mL of toluene, sodium carbonate (127.2 g, 1200 mmol), 600 mL of water, 200 mL of ethanol were added, and the mixture was stirred under nitrogen protection and heated to 40 °C. Then 13.9 g of catalyst PdCl2(PPh3)2was added, and the reaction was continued to reflux for 11 h. The reaction was stopped, and the mixture was cooled and filtered. The filtrate was separated, and the organic phase was heated and passed through a short column of alumina silica gel to remove color. Then the toluene was evaporated to about 500 mL, and the mixture was heated to 80 °C until it was completely dissolved. Then 150 mL of isopropanol was added, and the mixture was cooled to precipitate the solid. The solid was filtered and dried to obtain 82 g of intermediate M5 with a yield of 56.16%. The intermediate M5 was further recrystallized once by the same method to obtain a purity of 99.8%.

[0118] 2.7 Synthesis of compound II-2

[0119] The synthesis route of compound II-2 is as follows:

[0120]

[0121] Intermediate M4 (38.44 g, 73.5 mmol), intermediate M5 (25.61 g, 70 mmol), 150 mL of toluene, potassium carbonate (29.02 g, 210 mmol), 75 mL of water, 75 mL of ethanol were added into a round bottom flask, stirred under nitrogen protection, warmed to 40°C, 0.98 g of catalyst PdCl2(PPh3)2and 0.67 g of 2-di-tert-butylphosphine-2',4',6'-triisopropylbiphenyl were added, and the reaction was continued to reflux for 8 h, then the reaction was stopped, cooled, filtered, and the filter cake was added to 800 mL of o-dichlorobenzene and heated to decolorize the alumina silica gel short column, then the o-dichlorobenzene was evaporated to precipitate the solid, stirred to cool to room temperature, filtered and dried to obtain 40.66 g of white solid compound II-2, with a yield of 63.48%. Compound II-2 was further recrystallized once by the same method, and then further purified by vacuum sublimation, with a purity of 99.84%.

[0122] The characterization results of compound II-2 are as follows:

[0123] 1 HNMR (CDCI3, 400 MHz) δ 8.68-8.57 (m, 2H), 8.34 (dd, J = 8.6, 1.8 Hz, 2H), 8.25-8.16 (m, 4H), 8.07 (s, 2H), 8.04-7.97 (m, 3H), 7.95-7.87 (m, 4H), 7.84-7.77 (m, 2H), 7.73 (d, J = 1.5 Hz, 1H), 7.66-7.56 (m, 2H), 7.49-7.34 (m, 11H), 7.13 (ddd, J = 8.0, 7.3, 1.0 Hz, 1H).

[0124] 2.8 Synthesis of compound II-25

[0125] The synthesis route of compound II-25 is as follows:

[0126]

[0127] Intermediate M4 (25.2 g, 48.18 mmol), 2-chloro-4,6-diphenylpyrimidine (12.24 g, 45.89 mmol), 200 mL of toluene, potassium carbonate (19.03 g, 137.67 mmol), 60 mL of water, 100 mL of ethanol were added into a 500 mL round bottom flask, stirred under nitrogen protection, heated to 40 °C, 0.64 g of catalyst PdCl2(PPh3)2was added, and the reaction was continued to reflux for 3.5 h, then stopped, cooled, filtered, and the filter cake was added to 750 mL of o-dichlorobenzene and heated to decolorize the alumina silica gel short column, then the o-dichlorobenzene was evaporated to solid precipitation, stirred and cooled to room temperature, filtered and dried to obtain 33.04 g of white solid compound II-25 with a yield of 88.26%. Compound II-25 was further recrystallized once by the same method, and then further purified by vacuum sublimation with a purity of 99.97%.

[0128] The characterization results of compound II-25 are as follows:

[0129] 1 HNMR (CDCI3, 400 MHz) δ 9.08 (d, J = 1.4 Hz, 1H), 8.78 (d, J = 1.4 Hz, 1H), 8.31 (ddt, J = 13.3, 6.2, 1.7 Hz, 8H), 8.09 (d, J = 5.3 Hz, 3H), 7.70-7.64 (m, 2H), 7.60-7.46 (m, 13H), 7.21-7.16 (m, 1H).

[0130] 2.9 Synthesis of compound II-26

[0131] The synthesis route of compound II-25 is as follows:

[0132]

[0133] Intermediate M4 (25.2 g, 48.18 mmol), 2-chloro-4,6-diphenylpyrimidine (12.24 g, 45.89 mmol), 200 mL of toluene, potassium carbonate (19.03 g, 137.67 mmol), 60 mL of water, 100 mL of ethanol were added into a 500 mL round bottom flask, stirred under nitrogen protection, heated to 40 °C, 0.64 g of catalyst PdCl2(PPh3)2was added, and the reaction was continued to reflux for 3.5 h, then stopped, cooled, filtered, and the filter cake was added to 750 mL of o-dichlorobenzene and heated to decolorize the alumina silica gel short column, then the o-dichlorobenzene was evaporated to solid precipitation, stirred and cooled to room temperature, filtered and dried to obtain 33.04 g of white solid compound II-25 with a yield of 88.26%. Compound II-25 was further recrystallized once by the same method, and then further purified by vacuum sublimation with a purity of 99.97%.

[0134] The characterization results of compound II-26 are as follows:

[0135] 1 HNMR (CDCI3, 400 MHz) δ 8.88 (s, 1 H), 8.70 (s, 1 H), 8.49 (d, J = 7.1 Hz, 1 H), 8.40-8.29 (m, 2 H), 8.24-7.92 (m, 21 H), 7.71 (d, J = 8.1 Hz, 1 H), 7.61-7.47 (m, 6 H).

[0136] 2.10 Synthesis of compound II-49

[0137] The synthetic route of compound II-49 is as follows:

[0138]

[0139] Intermediate M4 (15 g, 28.68 mmol), 2-chloro-4,6-diphenyl-1,3,5-triazine (7.31 g, 27.31 mmol), 60 mL of toluene, potassium carbonate (11.32 g, 81.93 mmol), 30 mL of water, 30 mL of ethanol were added into a 250 mL round bottom flask, and stirred under nitrogen protection, and heated to 40°C, and 0.19 g of catalyst PdCl2(PPh3)2was added, and the temperature was continued to rise to reflux, and the reaction was stopped after 3.5 h, and after cooling, filtration was performed, and 850 ml of o-dichlorobenzene was added to heat the alumina silica gel short column to decolorize, and then o-dichlorobenzene was evaporated to precipitate solids, and after stirring and cooling to room temperature, filtration and drying were performed, to obtain 8.05 g of white solid compound II-49, with a yield of 36.1%. Compound II-49 was further recrystallized once by the same method, and then further purified by vacuum sublimation, with a purity of 99.94%.

[0140] The characterization results of compound II-49 are as follows:

[0141] 1 HNMR (CDCI3, 400 MHz) δ 8.88 (s, 1 H), 8.70 (s, 1 H), 8.49 (d, J = 7.1 Hz, 1 H), 8.40-8.29 (m, 2 H), 8.24-7.92 (m, 21 H), 7.71 (d, J = 8.1 Hz, 1 H), 7.61-7.47 (m, 6 H).

[0142] 2.11 Synthesis of compound II-54

[0143] The synthetic route of compound II-54 is as follows:

[0144]

[0145] The intermediate M4 (11.32 g, 21.64 mmol), 2-chloro-4-(3-(naphthalen-2-yl)phenyl)-6-phenyl-1,3,5-triazine (8.12 g, 20.61 mmol), 60 mL of toluene, potassium carbonate (8.54 g, 61.82 mmol), 25 mL of water, 30 mL of ethanol were added into a 250 mL round bottom flask, and stirred under nitrogen protection, and heated to 40°C, and 0.28 g of catalyst PdCl2(PPh3)2 was added, and continued to heat to reflux for 4 h, and then the reaction was stopped, and after cooling, filtration was performed, and 1000 mL of o-dichlorobenzene was added to heat the alumina silica gel short column to decolorize, and then o-dichlorobenzene was evaporated to precipitate a solid, and after stirring and cooling to room temperature, filtration and drying were performed, to obtain white solid compound II-54, with a yield of 40.49%. The compound II-54 was further recrystallized once by the same method, and then further purified by vacuum sublimation, with a purity of 99.93%.

[0146] The characterization results of the compound II-54 are as follows:

[0147] 1 HNMR (CDCl3, 400 MHz) δ 9.46-9.01 (m, 2H), 8.82 (ddd, J = 8.3, 2.9, 1.5 Hz, 4H), 8.30 (dd, J = 7.3, 1.7 Hz, 4H), 8.20-8.15 (m, 1H), 8.13-8.05 (m, 2H), 8.04-7.82 (m, 5H), 7.77-7.37 (m, 15H), 7.21 (t, J = 7.6 Hz, 1H).

[0148] 3. Thermodynamic property characterization

[0149] The glass transition temperature (Tg) was determined by differential scanning calorimetry (DSC, TA Instruments DSC25 differential scanning calorimeter) at a heating rate of 10°C / min; the decomposition temperature Td was the temperature at which 5% weight loss occurred under a nitrogen atmosphere, and was determined on a TGA55 thermal gravimetric analyzer from TA Instruments, with a nitrogen flow rate of 20 mL / min. The specific data are shown in Table 1 below.

[0150] Table 1

[0151]

[0152]

[0153] As can be seen from the data in the table, the glass transition temperatures of the compound represented by formula (I) and the compound represented by formula (II) used in the application are all above 120°C, and are not easy to crystallize, and have good film-forming properties. The thermal decomposition temperatures are all above 420°C, and are not easy to decompose, and have excellent thermal stability. NA in Table 1 indicates that the glass transition temperature was not measured.

[0154] 4. Preparation of an organic electroluminescent device

[0155] 4.1 The hole auxiliary layer materials used in the preparation of an organic electroluminescent device are as follows:

[0156]

[0157] 4.2 The electron transport layer materials used in the preparation of an organic electroluminescent device are as follows:

[0158]

[0159] 4.3 Other compounds used in the preparation of an organic electroluminescent device are as shown below:

[0160]

[0161] 4.4 Preparation of a blue organic electroluminescent device

[0162] Example 1

[0163] Reference Figure 2 The structure of the organic electroluminescent device shown in the figure, using Sunic sp1710 evaporation machine to manufacture organic electroluminescent device, the specific steps are as follows: the glass substrate 110 (corning glass 40mm x 40mm x 0.7mm) plated with ITO (indium tin oxide) with a thickness of 135nm is respectively washed with isopropanol and pure water for 5 minutes, and then cleaned with ultraviolet ozone, and then the glass substrate is transferred to the vacuum deposition chamber; compound I-3 doped with 4% HD is vacuum (about 10 -7 Torr) hot deposited on the transparent ITO electrode with a thickness of 20nm, forming a hole injection layer 130. On the hole injection layer 130, vacuum deposition of 120nm thick compound I-3 as a hole transport layer 140; then vacuum deposition of 10nm thick EB to form an electron blocking layer 141; then vacuum deposition of 25nm of BH doped with 2% BD by mass fraction as a light emitting layer 150; then vacuum deposition of Ⅱ-25 doped with 50% LiQ (lithium 8-hydroxyquinoline) to form an electron transport layer 160, with a thickness of 30nm; finally, 2nm thick metal ytterbium (Yb, electron injection layer 170) and 150nm of magnesium-silver alloy doped at a ratio of 10:1 are sequentially deposited to form a cathode 180; finally, the device is transferred from the deposition chamber to the glove box, and then packaged with UV curable epoxy resin and glass cover containing moisture absorbent to obtain an organic electroluminescent device. In the above manufacturing steps, the deposition rates of the organic materials, metal ytterbium and metal Mg are 0.1nm / s, 0.05nm / s and 0.2nm / s respectively.

[0164] The structure of the organic electroluminescent device is shown in the figure:

[0165] ITO (135 nm) / I-3:4% HD (20 nm) / I-3 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0166] -25: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0167] Example 2

[0168] The difference from Example 1 is that Compound II-26 is used instead of Compound II-25.

[0169] The structure of the organic electroluminescence element produced in this example is represented as:

[0170] ITO (135 nm) / I-3:4% HD (20 nm) / I-3 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0171] -26: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0172] Example 3

[0173] The difference from Example 1 is that Compound II-49 is used instead of Compound II-25.

[0174] The structure of the organic electroluminescence element produced in this example is represented as:

[0175] ITO (135 nm) / I-3:4% HD (20 nm) / I-3 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0176] -49: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0177] Example 4

[0178] The difference from Example 1 is that Compound I-7 is used instead of Compound I-3, and Compound II-2 is used instead of Compound II-25.

[0179] The structure of the organic electroluminescence element produced in this example is represented as:

[0180] ITO (135 nm) / I-7:4% HD (20 nm) / I-7 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0181] - 2: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0182] Example 5

[0183] The difference from Example 1 is that Compound I-7 is used instead of Compound I-3.

[0184] The structure of the organic electroluminescence element produced in this example is represented as:

[0185] ITO (135 nm) / I-7:4% HD (20 nm) / I-7 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0186] - 2: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0187] Example 6

[0188] The difference from Example 1 is that Compound I-7 is used instead of Compound I-3, and Compound II-26 is used instead of Compound II-25.

[0189] The structure of the organic electroluminescence element produced in this example is represented as:

[0190] ITO (135 nm) / I-7:4% HD (20 nm) / I-7 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0191] - 2: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0192] Example 7

[0193] The difference from Example 1 is that Compound I-7 is used instead of Compound I-3, and Compound II-49 is used instead of Compound II-25.

[0194] The structure of the organic electroluminescence element produced in this example is represented as:

[0195] ITO (135 nm) / I-7:4% HD (20 nm) / I-7 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II

[0196] - 2: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0197] Example 8

[0198] The difference from Example 1 is that Compound I-7 is used instead of Compound I-3, and Compound II-54 is used instead of Compound II-25.

[0199] The structure of the organic electroluminescence element produced in this example is represented as:

[0200] ITO (135 nm) / I-7:4% HD (20 nm) / I-7 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II-25: LiQ (5:5, 30 nm) / Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0201] -54: LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0202] Example 9

[0203] The difference from Example 1 is that Compound I-19 is used instead of Compound I-3.

[0204] The structure of the organic electroluminescence element produced in this example is represented as:

[0205] ITO (135 nm) / I-19:4% HD (20 nm) / I-19 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II-25: LiQ (5:5, 30 nm) / Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0206] Example 10

[0207] The difference from Example 1 is that Compound I-19 is used instead of Compound I-3, and Compound II-26 is used instead of Compound II-25.

[0208] The structure of the organic electroluminescence element produced in this example is represented as:

[0209] ITO (135 nm) / I-19:4% HD (20 nm) / I-19 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / II-26: LiQ (5:5, 30 nm) / Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0210] Comparative Example 1

[0211] The difference from Example 1 is that Compound ET is used instead of Compound II-25.

[0212] The structure of the organic electroluminescence element produced in this example is represented as:

[0213] ITO (135 nm) / I-3:4% HD (20 nm) / I-3 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / ET:LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0214] Comparative Example 2

[0215] The difference from Example 1 is that compound I-7 is used instead of compound I-3, and compound ET is used instead of compound II-25.

[0216] The structure of the organic electroluminescence element prepared in this example is represented as:

[0217] ITO (135 nm) / I-7:4% HD (20 nm) / I-7 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / ET:LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0218] Comparative Example 3

[0219] The difference from Example 1 is that compound I-19 is used instead of compound I-3, and compound ET is used instead of compound II-25.

[0220] The structure of the organic electroluminescence element prepared in this example is represented as:

[0221] ITO (135 nm) / I-19:4% HD (20 nm) / I-19 (120 nm) / EB (10 nm) / BH:4% BD (25 nm) / ET:LiQ (5:5, 30 nm) Yb (2 nm) / Mg:Ag (10:1, 150 nm).

[0222] The driving voltage, luminous efficiency, and EQE (external quantum efficiency) of the above-mentioned organic electroluminescence elements were tested by Suzhou Fudashan FS-100GA4, and all measurements were completed in room temperature atmosphere. The organic electroluminescence element was operated at 10 mA / cm 2 The specific performance data of the operating voltage (V), current efficiency (C.E.), external quantum efficiency (EQE), and color coordinates (CIEx, CIEy) at a current density of 10 mA / cm2are shown in Table 2.

[0223] Table 2

[0224]

[0225] From the results of Table 2, it can be seen that, compared with Comparative Example 1, Comparative Example 2 and Comparative Example 3, the driving voltage of the blue organic electroluminescent device is significantly reduced, and the efficiency is also significantly improved, when the compound represented by formula (I) is used as the hole auxiliary layer and the compound represented by formula (II) is used as the electron transport layer 160.

[0226] The preferred embodiments of the present application have been described above with the preferred embodiments, but the present application is not limited to the above examples. It will be appreciated by those skilled in the art that the present application can be variously changed and modified. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the present application.

Claims

1. An organic electroluminescent element comprising a hole auxiliary layer and an electron transport layer (160), characterized in that, The hole auxiliary layer contains one or more of compounds represented by formula (I); the electron transport layer (160) contains one or more of compounds represented by formula (II): In formula (I), Ar1(Ar2)N- is selected from the following groups: Ar3 and Ar4 are each independently selected from the following structures: In the above groups, the dotted line represents a connecting site bonded to nitrogen; Ar1(Ar2)N- and -NAr3(Ar4) are different; In formula (II), at least one of X1 to X3 is N; Ar5 and Ar6 are the same or different from each other and are each independently selected from the following structures:

2. The organic electroluminescent element according to claim 1, wherein The compound of formula (I) is selected from any one of the following structures:

3. The organic electroluminescent element according to claim 1 or 2, wherein The compound of formula (II) is selected from any one of the following structures:

4. The organic electroluminescent element according to claim 1, wherein The organic electroluminescence element comprises, in sequence, an anode (120), the hole auxiliary layer, a light-emitting layer (150), the electron transport layer (160), and a cathode (180); the hole auxiliary layer comprises, in sequence, a first hole auxiliary layer, a second hole auxiliary layer, and a third hole auxiliary layer, the first hole auxiliary layer is arranged in contact with the anode (120), and the third hole auxiliary layer is arranged in contact with the light-emitting layer (150); wherein the first hole auxiliary layer and the second hole auxiliary layer each contain a compound represented by formula (I), and the first hole auxiliary layer further contains a P-type doped compound.

5. The organic electroluminescent element according to claim 4, wherein The first hole auxiliary layer is a hole injection layer (130), the second hole auxiliary layer is a hole transport layer (140), and the third hole auxiliary layer is an electron blocking layer (141).

6. The organic electroluminescent element according to claim 4, wherein The material of the first hole auxiliary layer includes a compound represented by formula (I) and the P-type doped compound, and the doping amount of the P-type doped compound is 4-20 wt%.

7. The organic electroluminescent element according to claim 6, wherein The P-type doped compound is 8. The organic electroluminescent element according to claim 4, wherein The light-emitting layer (150) emits red light, green light, or blue light.

9. The organic electroluminescence element according to claim 8, wherein The material of the light-emitting layer (150) includes a host material and a doped material.

10. The organic electroluminescent element according to claim 9, wherein The host material is an aromatic condensed ring derivative or a heterocycle-containing compound; and the doped material is one or more of an aromatic amine derivative, a boron complex, a fluoranthene compound, and a metal complex.

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