An organic light-emitting auxiliary material and its preparation method and application

Abstract

The present invention provides an organic light-emitting auxiliary material and a preparation method and application thereof, and the general structural formula is shown in the specification. The organic light-emitting auxiliary material provided by the present invention uses 9-methyl-9-phenyl-9H-fluorene as a parent core, is directly connected to aromatic amine at the 2 position of the parent core, one side chain of the aromatic amine is connected to dibenzofuran at the 4 position, and the other side chain is connected to dimethylfluorene at the 2 position; the organic light-emitting auxiliary material can have excellent ultraviolet radiation resistance under strong ultraviolet light irradiation, and solves the problem of reduced life and efficiency of organic electroluminescent devices under ultraviolet light irradiation in natural environments.

Description

Technical Field

[0001] The present invention relates to the technical field of organic photoelectric materials, and in particular to an organic light-emitting auxiliary material, a preparation method thereof, and an application thereof in an organic electroluminescent device. Background Art

[0002] As we enter the 21st century, people demand a new generation of flat-panel displays that better meet future needs and offer improved performance. Organic light-emitting diodes (OLEDs), as a next-generation display technology, offer unparalleled advantages over liquid crystal flat-panel displays. OLEDs boast high brightness and efficiency, a compact size, wide viewing angles, and a fast response time. They can be applied to flexible substrates. Furthermore, the devices are bendable, enabling large-scale, large-area production and offering excellent cost-performance.

[0003] However, as the use of OLED devices becomes more and more extensive, there is an urgent need for highly stable OLED display devices for use in vehicle-mounted display scenarios. This is because the use environment of vehicle-mounted displays is more complex than that of mobile phone displays, especially in extreme environments, where high temperatures and strong ultraviolet light exposure can have a serious impact on the service life and brightness of OLED devices, thus limiting the use of OLED devices. For example, different displays made from the same panel, while the life of a television in an indoor environment is in line with expectations, will experience a serious decline in the life of a vehicle-mounted display, manifested as a significant decrease in brightness after a period of use; and existing organic electroluminescent materials generally have a problem of significantly reduced service life under strong ultraviolet light exposure.

[0004] Therefore, how to provide an OLED display device that is resistant to ultraviolet radiation and has good luminous efficiency, lifespan and operating voltage is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In light of this, the present invention provides an organic light-emitting auxiliary material and a preparation method thereof. The compound of the present invention uses 9-methyl-9-phenyl-9H-fluorene as a parent nucleus, with an aromatic amine directly linked at the 2-position of the parent nucleus. One side chain of the aromatic amine is linked to dibenzofuran at the 4-position, and the other side chain is linked to dimethylfluorene at the 2-position. The organic light-emitting auxiliary material exhibits excellent UV resistance under strong UV light, addressing the issues of decreased lifespan and efficiency of organic electroluminescent devices exposed to UV light in natural environments.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The first technical purpose of the present invention is to provide an organic light-emitting auxiliary material having a structure shown in Formula I:

[0008]

[0009] Wherein, R1, R2, and R3 are each independently selected from hydrogen or benzene.

[0010] Further, Formula I is selected from Formula Ia-Formula Id:

[0011]

[0012] Further, Formula I is selected from Formula Ie-Formula Ih:

[0013]

[0014] It should be noted that the group substitution positions involved in the present invention are defined as follows:

[0015]

[0016] Furthermore, the organic light-emitting auxiliary material is selected from any one of the compounds represented by the following structural formulas:

[0017]

[0018]

[0019]

[0020] The second technical purpose of the present invention is to provide a method for preparing the above-mentioned organic light-emitting auxiliary material, which specifically comprises the following steps:

[0021] Under nitrogen protection, reactant AI (1.0 eq) and reactant BI (1.1-1.3 eq) were added to a reaction vessel and dissolved in xylene, followed by the addition of a palladium catalyst (0.01-0.05 eq), a phosphorus ligand (0.02-0.15 eq), and a base (2.0-2.4 eq). After the addition, the reaction temperature was raised to 130-140° C., and the mixture was stirred for 8-12 hours. The mixture was filtered while hot using diatomaceous earth, and the filtrate was cooled to room temperature. Distilled water was then added to the filtrate for washing. After separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate. The combined organic layer was then dried over magnesium sulfate and purified by column chromatography to obtain intermediate CI.

[0022] Under N2 protection, the intermediate CI (1.0 eq) and the reactant DI (1.1-1.3 eq) were added to a reaction vessel and dissolved in xylene, and then a palladium catalyst (0.01-0.05 eq), a phosphorus ligand (0.02-0.15 eq), and a base (2.0-2.4 eq) were added; after the addition, the reaction temperature was raised to 130-140° C., and the mixture was stirred for 8-12 hours; the mixture was filtered while hot using diatomaceous earth, and the filtrate was cooled to room temperature, and then distilled water was added to the filtrate for washing. After separation, the organic phase was retained and the aqueous phase was extracted with ethyl acetate; the combined organic layer was then dried over magnesium sulfate and purified by column chromatography to obtain Formula I;

[0023] The specific synthetic route is as follows:

[0024]

[0025] wherein Hal1 and Hal2 are selected from Cl, Br, and I;

[0026] R1, R2, and R3 have the same meanings as given above.

[0027] Furthermore, the palladium catalyst is at least selected from one of Pd2(dba)3 (tris(dibenzylideneacetone)dipalladium), Pd(PPh3)4 (tetrakis(triphenylphosphine)palladium), PdCl2 (palladium dichloride), PdCl2(dppf) (1,1'-bis(diphenylphosphino)ferrocenepalladium chloride), Pd(OAc)2 (palladium acetate), and Pd(PPh3)2Cl2 (bis(triphenylphosphine)palladium dichloride); the base is at least selected from one of AcOK (potassium acetate), K2CO3, K3PO4, Na2CO3, CsF, Cs2CO3, and t-BuONa (sodium tert-butoxide); and the phosphine ligand is selected from PPh3 (triphenylphosphine), P(t-Bu)3 (tri-tert-butylphosphine), X-phos (2-cyclohexyl-2,4,6-triisopropylbiphenyl), PET3 (triethylphosphine), PMe3 (trimethylphosphine) or KPPh2 (potassium diphenylphosphonate).

[0028] Furthermore, the present invention also seeks to protect the use of the above-mentioned organic light-emitting auxiliary material in the preparation of an organic electroluminescent device.

[0029] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0030] The organic light-emitting auxiliary material provided by the present invention uses 9-methyl-9-phenyl-9H-fluorene as a parent core, is directly connected to an aromatic amine at the 2-position of the parent core, one side chain of the aromatic amine is connected to dibenzofuran at the 4-position, and the other side chain is connected to dimethylfluorene at the 2-position; the organic light-emitting auxiliary material can have excellent ultraviolet radiation resistance under strong ultraviolet light irradiation, and solves the problem of reduced lifespan and efficiency of organic electroluminescent devices under ultraviolet light irradiation in natural environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 is the H NMR spectrum of compound 1. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] Example 1: Synthesis of Compound 1

[0035]

[0036] Reactant A-1: ​​CAS: 2331184-24-6

[0037] Reactant B-1: CAS: 108714-73-4

[0038] Reactant C-1: CAS: 84761-86-4

[0039] Under N2 protection, reactant A-1 (1.0 eq) and reactant B-1 (1.2 eq) were added to a reaction vessel and dissolved in xylene, and then Pd(OAc)2 (0.01 eq), X-Phos (0.03 eq), and t-BuONa (2.4 eq) were added; after the addition, the reaction temperature was raised to 135°C, and the mixture was stirred for 8 hours; diatomaceous earth was used for hot filtration, and the filtrate was cooled to room temperature, and then distilled water was added to the filtrate for washing. After separation, the organic phase was retained and the aqueous phase was extracted with ethyl acetate; the combined organic layers were then dried over magnesium sulfate and purified by column chromatography to obtain intermediate C-1 (yield: 80%, test value MS (ESI, m / Z): [M+H]+=463.81).

[0040] Under N2 protection, intermediate C-1 (1.0 eq) and reactant D-1 (1.3 eq) were added to a reaction vessel and dissolved in xylene, and then Pd(OAc)2 (0.02 eq), X-Phos (0.04 eq), and t-BuONa (2.3 eq) were added; after the addition, the reaction temperature was raised to 135°C, and the mixture was stirred for 8 hours; diatomaceous earth was used for hot filtration, and the filtrate was cooled to room temperature, and then distilled water was added to the filtrate for washing. After separation, the organic phase was retained and the aqueous phase was extracted with ethyl acetate; the combined organic layers were then dried over magnesium sulfate and purified by column chromatography to obtain compound 1 (yield: 88%, test value MS (ESI, m / Z): [M+H]+=629.97).

[0041] Figure 1 : H NMR spectrum of compound 1

[0042] Characterization:

[0043] HPLC purity: >99.9%.

[0044] Elemental analysis:

[0045] Theoretical values: C, 89.63; H, 5.60; N, 2.22; O, 2.54

[0046] Measured values: C, 89.37; H, 5.78; N, 2.28; O, 2.61.

[0047] Example 2: Synthesis of Compound 3

[0048]

[0049] Reactant B-3: CAS: 2758134-82-4

[0050] Under N2 protection, reactant A-3 (1.0 eq) and reactant B-3 (1.3 eq) were added to a reaction vessel and dissolved in xylene, and then Pd(OAc)2 (0.02 eq), X-Phos (0.05 eq), and t-BuONa (2.2 eq) were added; after the addition, the reaction temperature was raised to 130°C, and the mixture was stirred for 12 hours; diatomaceous earth was used for hot filtration, and the filtrate was cooled to room temperature, and then distilled water was added to the filtrate for washing. After separation, the organic phase was retained and the aqueous phase was extracted with ethyl acetate; the combined organic layer was then dried over magnesium sulfate and purified by column chromatography to obtain intermediate C-3 (yield: 75%, test value MS (ESI, m / Z): [M+H]+=539.88).

[0051] Under N2 protection, intermediate C-3 (1.0 eq) and reactant D-3 (1.2 eq) were added to a reaction vessel and dissolved in xylene, and then Pd(OAc)2 (0.02 eq), X-Phos (0.05 eq), and t-BuONa (2.3 eq) were added; after the addition, the reaction temperature was raised to 135°C, and the mixture was stirred for 10 hours; diatomaceous earth was used for hot filtration, and the filtrate was cooled to room temperature, and then distilled water was added to the filtrate for washing. After separation, the organic phase was retained and the aqueous phase was extracted with ethyl acetate; the combined organic layers were then dried over magnesium sulfate and purified by column chromatography to obtain compound 3 (yield: 82%, test value MS (ESI, m / Z): [M+H]+=706.03).

[0052] Characterization:

[0053] HPLC purity: >99.8%.

[0054] Elemental analysis:

[0055] Theoretical values: C, 90.18; H, 5.57; N, 1.98; O, 2.27

[0056] Measured values: C, 90.04; H, 5.70; N, 2.02; O, 2.31.

[0057] Example 3: Synthesis of Compound 5

[0058]

[0059] Reactant D-5: CAS: 2379717-75-4

[0060] Intermediate C-5 is identical to intermediate C-3 and has the same synthetic route;

[0061] Under N2 protection, intermediate C-5 (1.0 eq) and reactant D-5 (1.2 eq) were added to a reaction vessel and dissolved in xylene, followed by the addition of Pd(OAc)2 (0.02 eq), X-Phos (0.05 eq), and t-BuONa (2.2 eq); after addition, the reaction temperature was raised to 135°C, and the mixture was stirred for 8 h; filtration was performed using diatomaceous earth while hot, and the filtrate was cooled to room temperature, followed by the addition of distilled water to the filtrate for washing. After separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate; the combined organic layers were then dried over magnesium sulfate and purified by column chromatography to obtain compound 5 (yield: 79%, test value MS (ESI, m / Z): [M+H]+=782.26).

[0062] Characterization:

[0063] HPLC purity: >99.8%.

[0064] Elemental analysis:

[0065] Theoretical values: C, 90.62; H, 5.54; N, 1.79; O, 2.05

[0066] Measured values: C, 90.41; H, 5.71; N, 1.85; O, 2.13.

[0067] Example 4-19

[0068] The following compounds were synthesized by referring to the synthesis methods of Examples 1 to 3. Their molecular formulas and mass spectra are shown in Table 1 below. The mass spectrometer model was Waters XEVO TQD, low precision, and ESI source testing.

[0069] Table 1 Molecular formula and mass spectrum

[0070]

[0071]

[0072] In addition, it should be noted that other compounds of the present application can be obtained by referring to the synthesis methods of the above-mentioned embodiments, so they will not be listed one by one here.

[0073] The present invention provides an organic electroluminescent device having a structure including a hole injection layer, a hole transport layer, an electron blocking layer, a luminescence-assisting layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, a capping layer, and the like as organic layers. However, the structure of the organic light-emitting element is not limited to this structure and may include fewer or more organic layers.

[0074] According to one embodiment of the present specification, the organic layer comprises a light-emitting auxiliary layer, and the light-emitting auxiliary layer comprises the compound represented by formula I prepared by the present invention.

[0075] When manufacturing an organic light-emitting device, the compound represented by Formula I can be deposited using either vacuum evaporation or solution coating to form an organic layer. Solution coating methods include, but are not limited to, spin coating, dip coating, doctor blade coating, inkjet printing, screen printing, spraying, and roller coating.

[0076] The organic light-emitting element of the present invention may be a top emission type, a bottom emission type, or a bi-directional emission type, depending on the materials used.

[0077] The device of the present invention can be used in organic light-emitting devices, organic solar cells, electronic paper, organic photoreceptors or organic thin film transistors.

[0078] Anode materials are generally preferred for their high work function to facilitate hole injection into the organic layer. Specific examples of anode materials that can be used in the present invention include metals such as vanadium, chromium, copper, zinc, and gold, or their alloys; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); combinations of metals and oxides such as ZnO:Al or SnO2:Sb; and conductive polymers such as polypyrrole and polyaniline.

[0079] The hole injection layer is preferably a p-doped hole injection layer, which means a hole injection layer doped with a p-dopant. A p-dopant is a material that imparts p-type semiconductor properties. P-type semiconductor properties refer to the ability to inject or transport holes at the HOMO energy level, i.e., a material having high hole conductivity.

[0080] The P-doped hole injection layer can be exemplified by the following compounds, but is not limited thereto.

[0081]

[0082]

[0083] The hole transport layer is placed between the anode and the light emitting layer, and it can not only be used to promote hole injection and / or hole transport, but also be used to prevent electron overflow.

[0084] The hole transport material can be selected from arylamine derivatives, conductive polymers, and block copolymers having both conjugated and non-conjugated parts. Specifically, the hole transport layer material is selected from the following compounds, but is not limited thereto.

[0085]

[0086]

[0087] The compound represented by general formula I of the present invention is used as a light-emitting auxiliary layer.

[0088] The light-emitting material of the light-emitting layer is a material that can receive holes and electrons from the hole transport layer and the electron transport layer, respectively, and combine them to emit light in the visible light region. It is preferably a material with high quantum efficiency for fluorescence or phosphorescence.

[0089] The light-emitting layer may include a host material and a dopant material.

[0090] The mass ratio of the main material to the doping material is 90-99.5:0.5-10.

[0091] Host materials include aromatic fused ring derivatives or heterocyclic compounds. Specifically, aromatic fused ring derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentacene derivatives, phenanthrene compounds, and fluoranthene compounds, while heterocyclic compounds include carbazole derivatives, dibenzofuran derivatives, and pyrimidine derivatives.

[0092] Specifically, the main material of the present invention is selected from the following compounds, but is not limited thereto.

[0093]

[0094]

[0095]

[0096] The doping material of the present invention includes fluorescent doping and phosphorescent doping, and can be selected from aromatic amine derivatives, styrylamine compounds, boron complexes, fluoranthene compounds, metal complexes, and the like.

[0097] Specifically, the doping material of the present invention is selected from the following compounds, but is not limited thereto.

[0098]

[0099] The electron transport region may include at least one of an electron buffer layer, a hole blocking layer, an electron transport layer, and an electron injection layer, and preferably at least one of an electron transport layer and an electron injection layer. The electron transport region is a layer that can improve the problem of deterioration of luminous brightness due to changes in current characteristics in the device when the device is exposed to high temperatures during the process of manufacturing the panel, and can control the charge flow characteristics.

[0100] Materials for the electron transport layer (hole blocking layer), derivatives of oxazole, imidazole, thiazole, triazine, etc., metal chelates, quinoline derivatives, oxaline derivatives, diazanthracene derivatives, diazophrenia derivatives, silicon-containing heterocyclic compounds, perfluorinated oligomers, etc.

[0101] Specifically, the electron transport layer material is selected from the following compounds, but is not limited thereto.

[0102]

[0103]

[0104] In certain embodiments of the present invention, the material of the electron injection layer includes oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fluorenylmethane, anthrone and their derivatives, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, ytterbium and other metals or their alloys, metal complexes or nitrogen-containing 5-membered ring derivatives, etc., but is not limited thereto.

[0105] The cathode material is preferably a material with a low work function to facilitate electron injection into the organic layer. Specific examples of cathode materials include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloys thereof, including multilayer structures such as LiF / Al, LiO2 / Al, and Mg / Ag.

[0106] There are no particular limitations on the materials of other layers in the OLED device except for the light-emitting auxiliary layer disclosed herein comprising Formula I. Existing hole injection materials, hole transport materials, dopant materials, hole blocking layer materials, electron transport layer materials, and electron injection materials can be used.

[0107] The organic electroluminescent composition and the organic electroluminescent device provided by the present invention are described in detail below with reference to specific embodiments.

[0108] Application example: Preparation of red organic electroluminescent devices:

[0109] a. ITO anode: Clean the ITO (indium tin oxide)-Ag-ITO (indium tin oxide) (coating thickness is 14nm / 150nm / 14nm) glass substrate in distilled water twice, ultrasonically clean it for 30 minutes, and then repeatedly clean it with distilled water twice, ultrasonically clean it for 10 minutes. After washing, bake it in a vacuum oven at 220℃ for 2 hours. After baking, cool it down and it can be used. Use the substrate as the anode and use an evaporation machine to carry out the evaporation device process, and evaporate other functional layers on it in sequence.

[0110] b. HIL (hole injection layer): The hole injection layer materials HT1-27 and P-5 were vacuum evaporated at a deposition rate of 97:3, and the thickness was 10 nm.

[0111] c. HTL (hole transport layer): At a deposition rate of 100 nm, HT 1-27 was vacuum-deposited on the hole injection layer as a hole transport layer.

[0112] d. Luminous auxiliary layer: The compound provided by the above formula I is vacuum-deposited on the hole transport layer at a deposition rate of 90 nm as a light-emitting auxiliary layer;

[0113] e. EML (luminescent layer): Then on the above-mentioned luminescent auxiliary layer, The evaporation rate is 40 nm, and the main material Host-15 and the dopant material Dopant-R-1 are vacuum evaporated to a thickness of 40 nm as the light-emitting layer; the evaporation rate ratio of Host-15 and Dopant-R-1 is 97:3.

[0114] f. HB (hole blocking layer): The evaporation rate was 5.0 nm, and ET-14 was vacuum evaporated to a thickness of 5.0 nm as a hole blocking layer.

[0115] g. ETL (Electron Transport Layer): The evaporation rate was 30 nm, and ET-1 and Liq were vacuum evaporated to a thickness of 30 nm as the electron transport layer; the evaporation rate ratio of ET-1 and Liq was 50:50.

[0116] h. EIL (electron injection layer): The evaporation rate is 1.0 nm, and a Yb film layer is evaporated to form an electron injection layer.

[0117] i. Cathode: The evaporation rate ratio is 1:9, and 13nm of magnesium and silver are evaporated to form a cathode.

[0118] j. Light extraction layer: At a deposition rate of , CPL with a thickness of 65 nm was vacuum-deposited on the cathode as a light extraction layer.

[0119] k. Package the vapor-deposited substrate. First, use the glue coating equipment to coat the cleaned cover with UV glue. Then move the coated cover to the pressing section, place the vapor-deposited substrate on the upper end of the cover, and finally bond the substrate and cover together using the bonding equipment, while completing the UV glue curing.

[0120] The materials required for each layer are as follows:

[0121]

[0122] Application Example 1-19

[0123] The organic electroluminescent devices of Application Examples 1-19 were prepared according to the above-mentioned method for preparing an organic electroluminescent device, and Formula I was replaced with corresponding compounds to form a light-emitting auxiliary layer.

[0124] Comparative Examples 1-15

[0125] Comparative Example 1

[0126] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 1, wherein the structural formula of the comparative compound 1 is as follows:

[0127] Comparative Example 2

[0128] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with the comparative compound 2, wherein the structural formula of the comparative compound 2 is as follows:

[0129] Comparative Example 3

[0130] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with the comparative compound 3, wherein the structural formula of the comparative compound 3 is as follows:

[0131] Comparative Example 4

[0132] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with the comparative compound 4, wherein the structural formula of the comparative compound 4 is as follows:

[0133] Comparative Example 5

[0134] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 5, wherein the structural formula of the comparative compound 5 is as follows:

[0135] Comparative Example 6

[0136] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 6, wherein the structural formula of the comparative compound 6 is as follows:

[0137] Comparative Example 7

[0138] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 7, wherein the structural formula of the comparative compound 7 is as follows:

[0139] Comparative Example 8

[0140] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 8, wherein the structural formula of the comparative compound 8 is as follows:

[0141] Comparative Example 9

[0142] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 9, wherein the structural formula of the comparative compound 9 is as follows:

[0143] Comparative Example 10

[0144] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced by a comparative compound 10, wherein the structural formula of the comparative compound 10 is as follows:

[0145] Comparative Example 11

[0146] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced by a comparative compound 11, wherein the structural formula of the comparative compound 11 is as follows:

[0147] Comparative Example 12

[0148] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced by a comparative compound 12, wherein the structural formula of the comparative compound 12 is as follows:

[0149] Comparative Example 13

[0150] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 13, wherein the structural formula of the comparative compound 13 is as follows:

[0151] Comparative Example 14

[0152] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 14, wherein the structural formula of the comparative compound 14 is as follows:

[0153] Comparative Example 15

[0154] An organic electroluminescent device was prepared according to the above-mentioned method for preparing an organic electroluminescent device, except that the compound 1 in Application Example 1 was replaced with a comparative compound 15, wherein the structural formula of the comparative compound 15 is as follows:

[0155]

[0156]

[0157] To simulate the extreme environment of strong UV radiation in the sun, two identical groups of the above devices were prepared at the same time, marked as Group A and Group B. The devices in Group A were exposed to strong UV light of 254nm for 120 hours at room temperature of 25 degrees. The UV intensity was controlled at 30mW / cm 2 , 250W, Group B devices were placed at room temperature of 25 degrees, without UV light, and placed for 120 hours. The driving voltage, luminous efficiency and life of Groups A and B devices were tested at the same time. The test results are shown in Table 2 (Group A, UV light irradiation) and Table 3 (Group B, no UV light irradiation):

[0158] Specifically, the driving voltage, luminous efficiency and life of the organic electroluminescent devices obtained from the above device examples 1-19 and device comparative examples 1-15 after irradiation of group A with ultraviolet light at a brightness of 6000 (nits) were characterized. The test results are shown in Table 2 below:

[0159] Table 2: Luminous characteristics test results (brightness value is 6000 nits)

[0160]

[0161]

[0162] The driving voltage, luminous efficiency, and lifespan of the organic electroluminescent devices obtained from the device application examples 1-19 and the device comparative examples 1-15 of group B without UV irradiation were characterized at a brightness of 6000 (nits). The test results are shown in Table 3 below:

[0163] Table 3: Luminous characteristics test results (brightness value is 6000 nits)

[0164]

[0165]

[0166] In order to study the effect of phenyl substitution on the dissociation energy of the compounds, the bond dissociation energy (BDE) of compound 1, compound 3 and comparison compound 13 was calculated using Gaussian16 software. The structure and fragment configuration were optimized using the b3lyp functional 6-31g* basis set. The structure and fragment energies were calculated using the b3lyp functional and 6-31g** basis set. The dissociation energy data are given in Table 4.

[0167] Table 4: Effect of phenyl substitution on the dissociation energy of compounds

[0168]

[0169] From the calculated data in Table 4, it can be seen that the phenyl substitution position affects the dissociation energy of the compound. The lower the dissociation energy, the more unstable the compound. In compound 1, compound 3, and comparative compound 13, the methyl connection bond in the 9-methyl-9-phenyl-9H-fluorene shown in the bond a position with the most unstable dissociation energy. Comparative compound 13 replaces a phenyl on 9-methyl-9-phenyl-9H-fluorene, further reducing the dissociation energy of a and b positions (respectively: 2.592eV, 3.070eV). Compound 3 replaces a phenyl on the dimethylfluorene of the side chain, and the dissociation energy of a, b, and c positions is almost unchanged (respectively: 2.603eV, 3.087eV, 2.841eV). It can be seen from the phenyl substitution that the phenyl substituent on 9-methyl-9-phenyl-9H-fluorene reduces the bond dissociation energy, causing life problems, while the phenyl substituent connected to the dimethylfluorene has little effect on stability. The compounds of the present invention have stronger resistance to ultraviolet light irradiation.

[0170] The compound of the present invention uses 9-methyl-9-phenyl-9H-fluorene as a parent nucleus, with an aromatic amine directly linked to the 2-position of the parent nucleus. One side chain of the aromatic amine is linked to dibenzofuran at the 4-position, and the other side chain is linked to dimethylfluorene at the 2-position. The compound of the present invention can maintain good stability under strong ultraviolet light irradiation. This is because, on the one hand, the 9-methyl-9-phenyl-9H-fluorene parent nucleus is more stable in terms of dissociation energy than the phenyl substitution on 9-methyl-9-phenyl-9H-fluorene. On the other hand, the different substitution positions affect the free radical activity of the compound. Under ultraviolet light irradiation, the compound decomposes, which impairs the overall performance of the device, especially significantly affecting the lifespan.

[0171] As shown in the test results in Tables 2 and 3, in organic electroluminescent devices not exposed to strong UV light, the comparative examples 1-15 and the compounds of the present invention exhibited similar performance in terms of driving voltage, lifespan, and efficiency. The driving voltage generally ranged from 3.26 to 3.37 V, the luminous efficiency ranged from 67.5 to 72.5 cd / A, and the lifespan ranged from 1554 to 1620 h. However, the performance of the organic electroluminescent devices after exposure to strong UV light showed significant differences between the comparative examples 1-15 and the compounds of the present invention.

[0172] After ultraviolet irradiation, although both the compound of the present invention and the comparative compound decreased, the degree of decrease of the compound of the present invention was much lower than that of the comparative compound. The overall driving voltage of the compound of the present invention after irradiation was about 3.42-3.60V, the luminous efficiency was about 57.9-63.9cd / A, and the lifespan was about 1315-1375h; while the driving voltage of the comparative compound 1-15 was about 3.72-3.82V, the luminous efficiency was about 48-53cd / A, and the lifespan was about 750-920h. The performance after ultraviolet irradiation of the compound of the present invention was much higher than that of the comparative compound. This shows that the compound of the present invention can avoid damage to the compound by ultraviolet free radicals in an extreme strong ultraviolet vehicle environment, maintain the overall performance of the device, especially the use in terms of lifespan.

[0173] The influence of substitution position directly affects the spatial structure of the compound. Different substitution sites result in different levels of resistance to ultraviolet light. The compounds of the present invention can avoid material cracking under strong ultraviolet light irradiation, which affects device performance. The dibenzofuran on the side chain of Compound 1 of the present invention is connected at the 4-position, and the dimethylfluorene is connected at the 2-position. The performance of the device of the present compound is similar to that of the comparative compounds 1-3 before ultraviolet light irradiation. After irradiation, the device performance of the present compound has a longer life and higher luminous efficiency. It can be seen that the substitution position on the side chain of the compound of the present invention is more stable and can effectively resist the compound decomposition under ultraviolet light irradiation.

[0174]

[0175] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic light-emitting auxiliary material, characterized in that: It has the structure shown in formula I: Wherein, R1, R2, and R3 are each independently selected from hydrogen or benzene.

2. The organic light-emitting auxiliary material according to claim 1, characterized in that: Formula I is selected from Formula Ia-Formula Id:

3. The organic light-emitting auxiliary material according to claim 2, characterized in that: Formula I is selected from Formula Ie-Formula Ih:

4. The organic light-emitting auxiliary material according to claim 1, characterized in that: The organic light-emitting auxiliary material is selected from any one of the compounds represented by the following structural formulas:

5. A method for preparing an organic light-emitting auxiliary material as claimed in claim 1, characterized in that: The method specifically comprises the following steps: Under N2 protection, reactant AI and reactant BI are added to a reaction vessel and dissolved in xylene, and then palladium catalyst, phosphine ligand and base are added, stirred and heated to 130-140°C, and the reaction is carried out at a constant temperature for 8-12 hours; after the reaction is completed, diatomaceous earth is used for hot suction filtration, and after the filtrate is cooled to room temperature, distilled water is added to the filtrate for washing, and the organic phase is retained after separation, and the aqueous phase is extracted with ethyl acetate; then the combined organic phase is dried with magnesium sulfate, and purified by column chromatography to finally obtain the intermediate CI; Under N2 protection, add intermediate CI and reactant DI to a reaction vessel and dissolve them in xylene, then add palladium catalyst, phosphine ligand and base, stir and heat to 130-140°C, and react at a constant temperature for 8-12h; after the reaction is completed, use diatomaceous earth to filter while hot, cool the filtrate to room temperature, add distilled water to the filtrate for washing, retain the organic phase after separation, and extract the aqueous phase with ethyl acetate; then use magnesium sulfate to dry the combined organic phase, and purify it by column chromatography to obtain formula I; The specific synthetic route is as follows: in, Hal1, Hal2 are selected from Cl, Br, I; R1, R2, and R3 are as defined in claim 1.

6. The method for preparing an organic light-emitting auxiliary material according to claim 5, characterized in that: The palladium catalyst is at least one selected from Pd2(dba)3, Pd(PPh3)4, PdCl2, PdCl2(dppf), Pd(OAc)2, Pd(PPh3)2Cl2; the base is selected from CH3COOK, K2CO3, K3PO4, Na2CO3, CsF, Cs2CO3 or t-BuONa, and the phosphine ligand is selected from P(t-Bu)3, X-phos, PET3, PMe3, PPh3 or KPPh2.

7. A use of the organic light-emitting auxiliary material according to claim 1 in the preparation of an organic electroluminescent device, characterized in that: The organic electroluminescent device comprises a first electrode, a second electrode, and one or more organic layers disposed between the first electrode and the second electrode; and, The organic layer includes a light-emitting auxiliary layer; the light-emitting auxiliary layer contains one or more organic light-emitting auxiliary materials.

8. The use according to claim 7, characterized in that: The organic layer includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a luminescence auxiliary layer, a luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer and a capping layer.

9. The use according to claim 8, characterized in that: The light-emitting layer comprises a main material and a doping material, and the mass ratio of the main material to the doping material is 90-99.5:0.5-10.

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