Luminescent auxiliary material as well as preparation method and application thereof

Abstract

The invention provides a light-emitting auxiliary material and a preparation method and application thereof, and belongs to the technical field of light-emitting materials, the structural formula of the light-emitting auxiliary material is shown in the general formula I. The light-emitting auxiliary material takes 9, 9-phenylalkyl fluorene as a parent nucleus, aryl and arylamine groups are connected to the two sides of fluorene of the 9, 9-phenylalkyl fluorene respectively, 9-phenylalkyl fluorene has relatively high glass transition temperature and quantum fluorescence efficiency, the stability and luminous efficiency of the compound can be effectively improved, the energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital can be flexibly adjusted by introducing an electron-donating group arylamine, and the energy barrier of hole injection can be effectively reduced; meanwhile, the other side is connected with an aryl group, so that a conjugated system can be effectively extended, a fluorescence quenching phenomenon caused by intermolecular pi-pi accumulation and excessive molecular aggregation is reduced, the service life of an OLED (Organic Light Emitting Diode) device can be effectively prolonged, the luminous efficiency of the OLED device can be effectively improved, and the driving voltage can be reduced by utilizing the light-emitting auxiliary material.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, and relates to a luminescent auxiliary material, its preparation method and application. Background Technology

[0002] Entering the 21st century, with the rapid development of technology and the continuous improvement of people's living standards, traditional flat panel displays can no longer meet people's diverse needs for future life, and there is an urgent need for a new generation of flat panel displays with superior performance. Among many emerging display technologies, display devices made of Organic Light-Emitting Diodes (OLEDs) have stood out. OLED display technology is based on the electroluminescence principle of organic materials. Under the influence of an electric field, holes and electrons recombine in organic materials and release energy, thereby exciting photons to achieve light emission. This unique light-emitting mechanism gives OLED display devices many unparalleled advantages: their small size allows for thinner and more compact designs of electronic devices; and their wide viewing angle greatly improves viewing comfort and convenience. Based on these outstanding advantages, OLED display devices have shown extremely broad application prospects in many display fields such as smartphones, tablet computers, televisions, and wearable devices.

[0003] OLEDs exhibit a multi-layered, "sandwich" structure, consisting of electrode material layers and organic functional materials sandwiched between them. These include: a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL). Hole transport materials typically have low highest occupied molecular orbitals (HOMO) values. Excitons generated in the emissive layer diffuse to the hole transport layer interface or side of the hole transport layer, ultimately leading to luminescence at the interface of the emissive layer or charge imbalance within the emissive layer. This results in luminescence at the hole transport layer interface, reducing the color purity and efficiency of the organic electroluminescent device and shortening its lifetime. In existing technologies, the hole transport barrier is high and the migration rate is low due to carrier localization between the hole transport layer and the emissive layer. Adding an emissive auxiliary layer between them can improve these problems, while also effectively improving stability and lifetime.

[0004] Therefore, there is an urgent need to develop a light-emitting auxiliary material that can reduce the hole transport energy barrier, improve the migration rate, and also has high luminous efficiency and long lifetime. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a luminescent auxiliary material, its preparation method, and its applications. The luminescent auxiliary material of the present invention uses 9-alkyl-9-phenylfluorene as the core, with aryl and aromatic amine groups attached to both sides of the fluorene core. 9-alkyl-9-phenylfluorene possesses a high glass transition temperature and quantum fluorescence efficiency, effectively improving the stability and luminescent efficiency of the compound. The introduction of the electron-donating aromatic amine group allows for flexible adjustment of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, effectively reducing the energy barrier for hole injection and improving hole transport rate and luminescent efficiency. Simultaneously, the attachment of aryl groups on the other side effectively extends the conjugated system, reducing intermolecular π-π stacking interactions and fluorescence quenching caused by excessive molecular aggregation. This luminescent auxiliary material can effectively improve the lifetime and luminescent efficiency of OLED devices while reducing the driving voltage.

[0006] To achieve this objective, the present invention adopts the following technical solution: On the one hand, the present invention provides a light-emitting auxiliary material, the structural formula of which is shown in general formula I: Wherein, R1 is selected from substituted or unsubstituted C1-C6 alkyl groups; Ar1 is selected from substituted or unsubstituted C6-C12 aryl groups; Ar2 and Ar3 are independently selected from substituted or unsubstituted C6-C18 aryl and substituted or unsubstituted C6-C18 heteroaryl, wherein the heteroatom is one or more of O, S, N, and Si; In general formula I, the hydrogen atom is either substituted with deuterium or not substituted with deuterium.

[0007] In this invention, C1-C6 can be C1, C2, C3, C4, C5 or C6, C6-C12 can be C6, C7, C8, C9, C10, C11 or C12, and C6-C18 can be C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17 or C18.

[0008] Furthermore, R1 is selected from substituted or unsubstituted methyl, substituted or unsubstituted ethyl, or substituted or unsubstituted tert-butyl.

[0009] Ar1 is selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl.

[0010] Furthermore, the compound with the luminescent assist function has a structure shown in any one of formulas I-1-I-3: Ar2 and Ar3 are each independently selected from the following substituted or unsubstituted groups: ; In this context, the asterisk represents the connection position of a group, while other groups without a marked connection position are connected at any substituted position.

[0011] The terms “substituted or unsubstituted C6-C18 aryl”, “substituted or unsubstituted C6-C12 aryl”, and “substituted or unsubstituted C6-C18 heteroaryl” refer to the number of carbon atoms in the aryl and heteroaryl groups, which represents the number of carbon atoms constituting the unsubstituted aryl group, the unsubstituted alkyl group, or the total number of heteroatoms and carbon atoms constituting the heteroaryl group, without considering the number of carbon atoms in the substituents.

[0012] The term "substitution" means substitution by one, two or more substituents selected from the following: deuterium, halogen, cyano, trifluoromethyl, trimethylsilyl, trimethylgermanium, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, phenyl, naphthyl, anthracene, phenanthrene, thiophene, furanyl, pyrrole, benzothiophene, benzofuranyl, pyridyl, indolyl, cyclopentyl, cyclohexyl, adamantyl, or substitution by two or more substituents linked together from the substituents shown above.

[0013] Furthermore, the luminescent auxiliary material is selected from any one of the following compounds: .

[0014] Secondly, the present invention also provides a method for synthesizing the luminescent auxiliary material as described above. The organic compound described in the present invention can be prepared by methods known to those skilled in the art. Alternatively, the following reaction process is preferred for preparation, and the specific synthetic route is as follows: In the above formula, R1, Ar1, Ar2, and Ar3 are the same as those defined above, and Hal1, Hal2, Hal3, and Hal3 are each independently selected from fluorine, chlorine, bromine, or iodine.

[0015] Preparation method: Step 1: Under nitrogen protection, raw material A (1.0 eq) and raw material B (1.0-1.2 eq) were dissolved in a mixed solution of toluene, ethanol, and water (V:V:V=2:1:1), and tetrakis(triphenylphosphine)palladium Pd(pph3)4 (0.05-0.08 eq) and potassium carbonate (2.5-3.0 eq) were added. The mixture was heated to 80-100℃ and refluxed for 12-24 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled to room temperature, and purified water and dichloromethane were added. After stirring, the mixture was allowed to stand and separate into layers. After separation, the mixture was purified by column chromatography to obtain intermediate 1. Step 2: Under nitrogen protection, intermediate 1 (1.0 eq) was dissolved in a mixed solution of methanol and water (V:V=1:1), and KOH solution (5.0-6.0 eq) was added. The mixture was heated to 70-90℃ and refluxed for 8-12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, the solvent was removed by a rotary evaporator to obtain intermediate 2. Step 3: Under nitrogen protection, intermediate 2 (1.0 eq) was dissolved in water, and dilute hydrochloric acid (HCl) was added to adjust the pH to less than 1. A solid precipitated out. The solid was filtered, washed, and dried in an oven at 70°C to obtain intermediate 3. Step 4: Under nitrogen protection, intermediate 3 (1.0 eq) was dissolved in DCM (dichloromethane), and trichloromethanesulfonic acid (10.0-12.0 eq) was slowly added dropwise. The reaction was carried out at room temperature for 6-12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, purified water and dichloromethane were added, stirred, and allowed to stand for separation. After separation, the mixture was purified by column chromatography to obtain intermediate 4. Step 5: Under nitrogen protection, intermediate 4 (1.0 eq) and starting material C (1.0-1.2 eq) were dissolved in a mixed solution of toluene, ethanol, and water (V:V:V=2:1:1), and Pd(pph3)4 (0.05-0.08 eq) and potassium carbonate (2.5-3.0 eq) were added. The mixture was heated to 80-100℃ and refluxed for 12-24 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled to room temperature, and purified water and dichloromethane were added. After stirring, the mixture was allowed to stand and separate into layers. After separation, the mixture was purified by column chromatography to obtain intermediate 5. Step 6: Under nitrogen protection, the system temperature was lowered to -78℃. Raw material D (1.0-1.5 eq) was dissolved in THF (tetrahydrofuran) and stirred for 10-30 minutes. Then, n-butyllithium (1.0-1.2 eq) was slowly added to the solution of raw material D. After reacting for 2-4 hours, the intermediate 5 (1.0 eq) solution was slowly added to the reaction flask and stirred until homogeneous. The refrigeration was stopped, and the mixture was raised to room temperature. The reaction was continued for 12-24 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, the mixture was washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with dichloromethane. The organic phases were combined and concentrated. The intermediate 6 was purified by column chromatography using a mixed solution of dichloromethane and petroleum as the eluent. Step 7: Under nitrogen protection, the system temperature was lowered to -10℃, intermediate 6 was dissolved in DCM, and raw material E (1.0-1.5 eq) and methanesulfonic acid MSA (2.0-3.0 eq) were added to it. After complete dissolution, the mixture was transferred to room temperature and stirred for 6-8 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, a solid precipitated out. The solid was filtered, washed, and dried in an oven at 70℃ to obtain intermediate 7. Step 8: Under nitrogen protection, intermediate 7 (1.0 eq) was dissolved in THF, and then t-BuOK (5.0-6.0 eq) was slowly added to the reaction flask. Starting material F (5.0 eq) was slowly added dropwise, and the temperature was raised to 90-100℃. The reaction was carried out for 12-24 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. A small amount of dichloromethane was used to completely dissolve the solid organic matter, which was then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain the solid, which was then washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 8. Step 9: Under nitrogen atmosphere, intermediate 8 (1.0 eq) was dissolved in TOL (toluene), and starting material G (1.0 eq) was dissolved in TOL. Then, starting material G was slowly added to the intermediate 5 solution. After three gas purgings, tris(dibenzylacetone)dipalladium (0.01-0.03 eq), tri-tert-butylphosphine (0.05-0.08 eq), and sodium tert-butoxide (2.0-2.5 eq) were added under nitrogen protection. The mixture was stirred thoroughly and heated to 100-110℃ for 4-8 hours. The reaction was detected by thin-layer chromatography. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature, washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were concentrated, and purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to obtain chemical formula I. The present invention involves a series of palladium-catalyzed coupling reactions. On the one hand, it utilizes the difference in activity between I and Br, which is greater than that of Cl. On the other hand, it controls the reaction sites by controlling the reaction conditions. Furthermore, it purifies the reaction by column chromatography or silica gel funnel to remove byproducts and obtain the target compound.

[0016] Another object of the present invention is to provide an organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode and an organic layer, the organic layer comprising a light-emitting auxiliary layer, the light-emitting auxiliary layer comprising the light-emitting auxiliary material as described above.

[0017] According to one embodiment of this specification, the compound of chemical formula I prepared in this application is used as a light-emitting auxiliary layer material.

[0018] Regarding the compound represented by the above chemical formula I, the organic layer can be formed using either vacuum evaporation or solution coating methods when manufacturing organic light-emitting elements. Solution coating methods include, but are not limited to, spin coating, dip coating, blade coating, inkjet printing, screen printing, spray coating, and roller coating.

[0019] Preferably, the organic layer further includes any one or a combination of at least two of the following: a hole injection layer, a light-emitting layer, a hole blocking layer, an electron transport layer, a charge generation layer, and an electron injection layer.

[0020] The light-emitting device of the present invention can be a top-emitting type, a bottom-emitting type, or a bidirectional-emitting type, depending on the material used.

[0021] As an anode material, a material with a high work function is generally preferred to facilitate hole injection into the organic material layer. Specific examples of anode materials that can be used in this invention include: metals, such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; 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; conductive polymers, such as poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxo)thiophene] (PEDOT), polypyrrole, and polyaniline, but not limited thereto.

[0022] Hole-injecting materials are those that advantageously receive holes from the anode at low voltages, and the highest occupied molecular orbital (HOMO) of the hole-injecting material is preferably between the work function of the anode material and the HOMO of the surrounding organic material layer. Specific examples of hole-injecting materials include, but are not limited to, metalloporphyrins, oligothiophenes, arylamine-based organic materials, hexanitrile hexaazabenzophenanthrene-based organic materials, quinacridone-based organic materials, perylene-based organic materials, anthraquinones, and conductive polymers based on polyaniline and polythiophene, and may also include other compounds capable of p-doping.

[0023] Hole transport materials are materials capable of receiving holes from the anode or hole injection layer and transporting them to the light-emitting layer, and materials with high hole mobility are suitable. Specific examples include, but are not limited to, arylamine-based organic materials, conductive polymers, and block copolymers having both conjugated and non-conjugated parts.

[0024] An auxiliary light-emitting layer (multilayer hole transport layer) is added between the hole transport layer and the light-emitting layer. The auxiliary light-emitting layer primarily assists the hole transport layer and is therefore sometimes referred to as a second hole transport layer. This layer allows holes transferred from the anode to smoothly move to the light-emitting layer and blocks electrons transferred from the cathode, confining them within the light-emitting layer. This reduces the potential barrier between the hole transport layer and the light-emitting layer, lowers the driving voltage of the light-emitting device, and further increases hole utilization, thereby improving the device's luminous efficiency and lifetime.

[0025] An electron blocking layer can be disposed between the hole transport layer and the light-emitting layer. Materials known in the art, such as arylamine-based organic materials, can be used as the electron blocking layer.

[0026] The luminescent layer can emit red, green, or blue light and can be formed from phosphorescent or fluorescent materials. The luminescent material is a material capable of emitting light in the visible light region by receiving holes and electrons from the hole transport layer and electron transport layer, respectively, and by combining the holes with the electrons, and is preferably a material with favorable quantum efficiency for fluorescence or phosphorescence. Specific examples include: 8-hydroxyquinoline aluminum ligand (Alq3); carbazole-based compounds; dipolystyrene-based compounds; BAlq; 10-hydroxybenzoquinoline-metal compounds; compounds based on benzocarbazole, benzothiazole, and benzimidazole; polymers based on poly(p-phenylenevinylene) (PPV); spirocyclic compounds; polyfluorene; fluorene, etc., but not limited to these.

[0027] The main materials of the luminescent layer include fused aromatic ring derivatives and heterocyclic compounds. Specifically, fused aromatic ring derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentanebenzene derivatives, phenanthrene compounds, fluoranthene compounds, etc., and heterocyclic compounds include carbazole derivatives, dibenzofuran derivatives, ladder-type furan compounds, pyrimidine derivatives, etc., however, the materials are not limited to these.

[0028] The hole blocking layer can be disposed between the electron transport layer and the light-emitting layer, and can be made of materials known in the art, such as triazine-based compounds.

[0029] An electron transport layer can facilitate electron transport. Electron transport materials are materials that advantageously receive electrons from the cathode and transport them to the light-emitting layer; materials with high electron mobility are suitable. Electron transport layers can include electron buffer layers, hole blocking layers, and electron transport layers themselves.

[0030] The electron injection layer can promote electron injection. Preferred electron injection materials are compounds that possess electron transport capabilities, exhibit an electron injection effect from the cathode, demonstrate excellent electron injection effects on the luminescent layer or luminescent material, prevent excitons generated in the luminescent layer from migrating to the hole injection layer, and, in addition, possess excellent thin film forming capabilities. Specific examples include fluorenones, anthraquinone dimethane, biphenylquinone, thiamethane dioxide, azoles, diazoles, triazoles, imidazoles, perylenetetracarboxylic acid, fluorenemethane, anthrones, and their derivatives, metal complexes, nitrogen-containing 5-membered ring derivatives, etc., but are not limited to these.

[0031] As cathode materials, materials with low work functions are generally preferred to facilitate electron injection into the organic material 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; multilayer materials, such as LiF / Al or LiO2 / Al; and so on, but are not limited to these.

[0032] In addition to the light-emitting auxiliary layer of the present invention containing chemical formula I, existing hole injection materials, hole transport materials, hole transport auxiliary materials, dopant materials, hole blocking layer materials, electron transport layer materials and electron injection materials can be used for other layer materials in OLED devices.

[0033] Compared with the prior art, the present invention has the following beneficial effects: The luminescent auxiliary material provided by this invention uses 9,9-phenylalkylfluorene as the core, with aryl and aromatic amine groups attached to both sides of the fluorene core. 9,9-phenylalkylfluorene has a high glass transition temperature and quantum fluorescence efficiency, effectively improving the stability and luminescence efficiency of the compound. The introduction of the electron-donating aromatic amine group allows for flexible adjustment of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, effectively reducing the energy barrier for hole injection and improving hole transport rate and luminescence efficiency. Simultaneously, the attachment of aryl groups on the other side effectively extends the conjugated system, reducing intermolecular π-π stacking interactions and fluorescence quenching caused by excessive molecular aggregation. This luminescent auxiliary material can effectively improve the lifetime and luminescence efficiency of OLED devices while reducing the driving voltage. Attached Figure Description

[0034] Figure 1 This is the 1H NMR spectrum of compound 49 in Example 1 of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0036] It should be noted that the series of palladium-catalyzed coupling reactions in this invention utilize the difference in reactivity between I and Br (which is greater than that of Cl) and the reaction sites are controlled by adjusting the reaction conditions. Furthermore, the reactions are purified by column chromatography or through a silica gel funnel to remove byproducts, yielding the target compound. The following are common knowledge references used in the synthesis of the compounds in this invention: Organometallic Chemistry (6th Edition), Robert H. Crabtree, published by East China University of Science and Technology Press, Shanghai, September 00, 2017, ISBN: 978-7-5628-5111-0, page 388.

[0037] Organic Chemistry and Optoelectronic Materials Experiment Tutorial, Chen Runfeng, Publisher: Southeast University Press, Publication Date: 2019-11-00, ISBN: 9787564184230, Page 174.

[0038] In addition, the values ​​given in the following embodiments are as accurate as possible, but those skilled in the art will understand that due to unavoidable measurement errors and experimental operation problems, each number should be understood as an approximation rather than an absolutely accurate value.

[0039] Unless otherwise stated, the raw materials and reagents used in the following examples are all commercially available products.

[0040] Example 1 Synthesis of Compound 49 Step 1: Under nitrogen protection, raw material A-49 (1.0 eq, CAS No.: 1093418-75-7) and raw material B-49 (1.2 eq, CAS No.: 3900-89-8) were dissolved in a mixed solution of toluene, ethanol, and water (V:V:V=2:1:1). Pd(pph3)4 (0.08 eq) and potassium carbonate (3.0 eq) were added to the solution. The mixture was heated to 80 °C and refluxed for 12-24 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled to room temperature, and purified water and dichloromethane were added. After stirring, the mixture was allowed to stand and separate into layers. After separation, the mixture was purified by column chromatography to obtain intermediate 1 (yield: 72.6%).

[0041] Step 2: Under nitrogen protection, intermediate 1 (1.0 eq) was dissolved in a mixed solution of methanol and water (V:V=1:1), and KOH solution (5.0 eq) was added. The mixture was heated to 70 °C and refluxed for 8-12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, the solvent was removed by a rotary evaporator to obtain intermediate 2 (yield: 79.6%).

[0042] Step 3: Under nitrogen protection, intermediate 2 (1.0 eq) was dissolved in water, and dilute hydrochloric acid (HCl) was added to adjust the pH to less than 1. A solid precipitated out. The solid was filtered, washed, and dried in an oven at 70°C to obtain intermediate 3 (yield: 88.1%).

[0043] Step 4: Under nitrogen protection, intermediate 3 (1.0 eq) was dissolved in DCM, and trichloromethanesulfonic acid (10.0 eq) was slowly added dropwise. The reaction was carried out at room temperature for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, purified water and dichloromethane were added, stirred, and allowed to stand for separation. After separation, the mixture was purified by column chromatography to obtain intermediate 4 (yield: 70.5%).

[0044] Step 5: Under nitrogen protection, intermediate 4 (1.0 eq) and starting material C-49 (1.2 eq, CAS No.: 98-80-6) were dissolved in a mixed solution of toluene, ethanol, and water (V:V:V=2:1:1), and Pd(pph3)4 (0.08 eq) and potassium carbonate (3.0 eq) were added. The mixture was heated to 80 °C and refluxed for 24 h. The reaction was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled to room temperature, and purified water and dichloromethane were added. After stirring, the mixture was allowed to stand and separate into layers. After separation, the mixture was purified by column chromatography to obtain intermediate 5 (yield: 83.4%).

[0045] Step 6: Under nitrogen protection, the system temperature was lowered to -78℃. Raw material D-49 (1.2 eq, CAS No.: 108-86-1) was dissolved in THF and stirred for 10 minutes. Then, n-butyllithium (1.0 eq) was slowly added to the solution of raw material D. After reacting for 2 hours, intermediate 5 (1.0 eq) solution was slowly added to the reaction flask and stirred until homogeneous. The refrigeration was stopped, and the mixture was raised to room temperature and reacted for another 12 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, the mixture was washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with dichloromethane. The organic phases were combined and concentrated. The intermediate 6 was purified by column chromatography using a mixed solution of dichloromethane and petroleum as the eluent (yield: 69.4%).

[0046] Step 7: Under nitrogen protection, the system temperature was lowered to -10℃, intermediate 6 was dissolved in DCM, and raw material E-49 (1.2 eq, CAS No.: 617-86-7) and methanesulfonic acid MSA (3.0 eq) were added. After complete dissolution, the mixture was transferred to room temperature and stirred for 8 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, a solid precipitated out. The solid was filtered, washed, and dried in an oven at 70℃ to obtain intermediate 7 (yield: 72.6%).

[0047] Step 8: Under nitrogen protection, intermediate 7 (1.0 eq) was dissolved in THF, and then t-BuOK (5.0 eq) was slowly added to the reaction flask. Starting material F-49 (5.0 eq, CAS No.: 74-88-4) was slowly added dropwise. The mixture was heated to 90°C and reacted for 12 h. The reaction was detected by thin-layer chromatography. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried with anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator. A small amount of dichloromethane was used to completely dissolve the solid organic matter, which was then slowly added dropwise to a petroleum ether solution. After stirring until homogeneous, a precipitate formed. The precipitate was filtered to obtain the solid, which was then washed successively with anhydrous ethanol and petroleum ether, and dried to obtain intermediate 8 (yield: 66.7%).

[0048] Step 9: Under nitrogen atmosphere, intermediate 8 (1.0 eq) was dissolved in TOL, and starting material G (1.0 eq, CAS No.: 897671-69-1) was dissolved in TOL. Then, starting material G-49 was slowly added to the intermediate 5 solution. After three gas purgings, tris(dibenzylacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.05 eq), and sodium tert-butoxide (2.0 eq) were added under nitrogen protection. The mixture was stirred thoroughly and heated to 110 °C for 4 h. The reaction was detected by thin-layer chromatography. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature, washed three times with water, and the organic phase was retained. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were concentrated, and compound 49 was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent (yield: 84.9%).

[0049] The obtained compound 49 was analyzed, and the results are as follows: HPLC purity: >99.5%; Test value ((ESI, m / Z): [M+H]+): 691.48; Elemental analysis: Test values ​​are: C, 91.92; H, 6.07; N, 2.11.

[0050] The proton NMR spectrum of compound 49 is as follows: Figure 1 As shown.

[0051] Example 1 of Red Light Device Anode: ITO anode: An ITO (Indium Tin Oxide)-Ag-ITO (Indium Tin Oxide) glass substrate with a coating thickness of 150nm is cleaned twice in distilled water, ultrasonically washed for 30 minutes, then repeatedly cleaned twice with distilled water, ultrasonically washed for 10 minutes. After washing, it is baked in a vacuum oven at 220℃ for 2 hours. After baking, it is cooled before use. Using this substrate as the anode, the device deposition process is carried out using a vapor deposition machine, and other functional layers are sequentially deposited on it.

[0052] First hole injection layer: On the anode layer after the above washing, HT-1 and P-dopant-1 with a thickness of 10 nm are deposited using a vacuum evaporation device, with the mass ratio of HT-1 to P-dopant-1 being 97:3 as the first hole injection layer. First hole transport layer: On the first hole injection layer mentioned above, a 24nm thick HT-1 is then deposited as the first hole transport layer.

[0053] First luminescent auxiliary layer: Subsequently, a compound 49 with a thickness of 5 nm is deposited on the aforementioned first hole transport layer as the first luminescent auxiliary layer.

[0054] First light-emitting layer: After the first electron blocking material is deposited, the light-emitting layer of the OLED light-emitting device is fabricated. Its structure includes OLED light-emitting layer using RH-1 as the main material and RD-1 as the doping material. The doping ratio of the doping material is 3% by weight, and the thickness of the light-emitting layer is 20nm.

[0055] First hole blocking layer: After the first light-emitting layer mentioned above, 5nm of HB-1 is deposited as the first hole blocking layer; First electron transport layer: After the first hole blocking layer mentioned above, 10 nm of ET-1 and Liq are vacuum-deposited, with an ET-1:Liq mass ratio of 1:1, as the first electron transport layer.

[0056] NCGL layer: On the first electron transport layer, an N-type charge generation layer (NCGL layer) is deposited by vacuum evaporation device, wherein the mass ratio of NCGL to Yb is 95:5 and the film thickness is 20nm.

[0057] PCGL layer: On the NCGL layer, a co-evaporated layer of HT-1 and P-1 with a thickness of 10nm is deposited using a vacuum evaporation device. The mass ratio of HT-1 to P-1 is 95:5 as the PCGL layer.

[0058] Second hole transport layer: HT-1 with a thickness of 30nm is then deposited as the second hole transport layer.

[0059] Second luminescent auxiliary layer: Subsequently, a compound 49 with a thickness of 5 nm is deposited on the above-mentioned second hole transport layer as a second luminescent auxiliary layer.

[0060] Second light-emitting layer: After the above-mentioned second electron blocking material is deposited, the second light-emitting layer of the OLED light-emitting device is fabricated. Its structure includes that the OLED second light-emitting layer uses RH-1 as the main material and RD-1 as the doping material. The doping ratio of the doping material is 3% by weight, and the thickness of the light-emitting layer is 20nm.

[0061] Second hole blocking layer: After the above-mentioned second light-emitting layer, a 5nm HB-1 layer is vacuum-deposited. This layer is the second hole blocking layer.

[0062] Second electron transport layer: 15 nm of ET-1 and Liq are deposited on the second hole blocking layer, with an ET-1:Liq mass ratio of 1:1 as the second electron transport layer.

[0063] Second electron injection layer: On the second electron transport layer, a Yb film with a thickness of 1 nm is fabricated as the second electron injection layer using a vacuum evaporation device.

[0064] Cathode: A 13nm Mg:Ag electrode layer is deposited by vapor deposition, with a Mg:Ag mass ratio of 1:9. This layer serves as the cathode layer.

[0065] Light extraction layer: A 65nm thick CPL-1 layer is vacuum-deposited on the cathode as the light extraction layer; The substrate after vapor deposition is encapsulated. First, the cleaned cover plate is coated with UV adhesive using an adhesive coating equipment. Then, the coated cover plate is moved to the lamination section, and the vapor-deposited substrate is placed on the top of the cover plate. Finally, the substrate and cover plate are laminated under the action of the lamination equipment, and the UV adhesive is cured by light.

[0066] The material structure used is shown below: Organic electroluminescent devices of application examples 2-46 were prepared according to the above-described method for preparing organic electroluminescent devices, except that compound 49 in device example 1 was replaced with compounds 1, 3, 4, 7, 11, 17, 27, 29, 31, 37, 42, 46, 51, 54, 60, 63, 67, 72, 78, 82, 88, 90, 92, 95, 99, 104, 108, 113, 127, 134, 137, 144, 151, 162, 170, 175, 186, 194, 206, 214, 221, 231, 238, 246, and 258 to form a light-emitting auxiliary layer.

[0067] Device Comparison Examples 1-12 This comparative example provides an organic electroluminescent device. The only difference between this organic electroluminescent device and device example 1 is that the organic electroluminescent device is prepared by evaporation using existing comparative compounds a, b, c, d, e, f, g, h, i, j, k, and l instead of the luminescent auxiliary material (compound 49) in device example 1. Comparative examples 1-12 are prepared by this method. The chemical structural formulas of compounds a, b, c, d, e, f, g, h, i, j, k, and l are as follows: The driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices containing luminescent auxiliary materials obtained by applying the above devices in Examples 1-46 and Comparative Examples 1-12 were characterized at a brightness of 6000 nits. The test results are shown in Table 1.

[0068] Table 1. Results of luminous properties test (luminance value 6000 nits) As shown in Table 1, changing the substituents and their positions alters the device performance, improving luminous efficiency and lifetime to varying degrees. The table also shows that, compared to existing organic electroluminescent devices provided in Comparative Examples 1-12, the OLED devices prepared using the luminescent auxiliary materials provided in the embodiments of this invention (Examples 1-46) exhibit a significant advantage in device lifetime, increasing it by 16.73-34.15% compared to the comparative examples. Furthermore, the luminescent auxiliary materials also show some improvement in device driving voltage and luminous efficiency, reducing the driving voltage by 2.42-9.15% and increasing the luminous efficiency by 3.83-18.43% compared to the comparative examples.

[0069] Compound 27 is a parallel comparative example with comparative compound e, compound 29 is a parallel comparative example with comparative compound g, and compound 31 is a parallel comparative example with comparative compound h. The difference between them lies in the parent core. The parent core of compounds 27, 29, and 31 in this invention is 9-methyl-9-phenylfluorene, while the parent core of comparative compounds e, f, and h is 9,9-diphenylfluorene. An excessive amount of phenyl groups increases the packing density and steric hindrance of the compounds, affecting the deposition temperature and thus reducing luminous efficiency and lifetime. 9-methyl-9-phenylfluorene has significant conjugation properties, which can improve intermolecular stacking and increase the degree of horizontal alignment, resulting in effective horizontal alignment of molecules and thus significantly improving luminous efficiency and device lifetime.

[0070] Compound 49 and comparative compound b are parallel comparative examples, and compound 54 and comparative compound j are parallel comparative examples. The difference between the two lies in whether the parent core 9-methyl-9-phenylfluorene contains an aryl substituent. By attaching an aryl group to the parent core 9-methyl-9-phenylfluorene, compounds 49 and 54 of the present invention can effectively extend the conjugated system, reduce the π-π stacking effect between molecules and the fluorescence quenching phenomenon caused by excessive molecular aggregation, and effectively improve the luminescence efficiency and device lifetime.

[0071] Comparative compound e and comparative compound f are parallel comparative examples. The difference between the two lies in the different substituents attached to 9,9-diphenylfluorene. Comparative compound e has an aryl group attached to the core, while comparative compound f has a heteroaryl group attached. By comparing the device data of the two, it can be seen that when the core is attached to an aryl group, it has a lower driving voltage, better luminous efficiency, and longer device lifetime.

[0072] As can be seen from the parallel comparisons above, the embodiments of the present invention, by attaching aryl groups and aromatic amino groups to both sides of the parent core based on 9-alkyl-9-phenylfluorene, possess a high triplet energy level, reducing the energy difference between energy levels and increasing the stability of the material. As can be seen from the data in Table 1, the compounds of the present invention exhibit longer lifetime and better luminous efficiency in red light devices.

[0073] The applicant declares that the present invention is illustrated by the above embodiments to demonstrate the luminescent auxiliary material, its preparation method, and its application. However, the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A luminescent auxiliary material, characterized in that, The luminescent auxiliary material has a structure as shown in general formula I: ； Wherein, R1 is selected from substituted or unsubstituted C1-C6 alkyl groups; Ar1 is selected from substituted or unsubstituted C6-C12 aryl groups; Ar2 and Ar3 are independently selected from substituted or unsubstituted C6-C18 aryl and substituted or unsubstituted C6-C18 heteroaryl, wherein the heteroatom is one or more of O, S, N, and Si; In general formula I, the hydrogen atom may be either substituted with deuterium or not substituted with deuterium; The substitution refers to substitution by one, two or more substituents selected from the following: deuterium, halogen, cyano, trifluoromethyl, trimethylsilyl, trimethylgermanium, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, 1-methylhexyl, phenyl, naphthyl, anthracene, phenanthrene, thiophene, furanyl, pyrrole, benzothiophene, benzofuranyl, pyridyl, indolyl, cyclopentyl, cyclohexyl, adamantyl, or substitution by two or more substituents linked together from the substituents shown above.

2. The luminescent auxiliary material according to claim 1, characterized in that, R1 is selected from substituted or unsubstituted methyl, substituted or unsubstituted ethyl, or substituted or unsubstituted tert-butyl.

3. The luminescent auxiliary material according to claim 1, characterized in that, Ar1 is selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl.

4. The luminescent auxiliary material according to claim 1, characterized in that, The compound with the luminescent assist function has a structure shown in any one of formulas I-1-I-3: ； Ar2 and Ar3 are each independently selected from the following substituted or unsubstituted groups: ； In this context, the asterisk represents the connection position of a group, while other groups without a marked connection position are connected at any substituted position.

5. The luminescent auxiliary material according to claim 1, characterized in that, The luminescent auxiliary material is selected from any one of the following compounds: 。 6. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes an anode, a cathode, and an organic layer, wherein the organic layer includes a light-emitting auxiliary layer, and the light-emitting auxiliary layer includes the light-emitting auxiliary material according to any one of claims 1-5.

7. The organic electroluminescent device according to claim 6, characterized in that, The organic layer further includes any one or a combination of at least two of the following: a hole injection layer, a light-emitting layer, a hole blocking layer, an electron transport layer, a charge generation layer, and an electron injection layer.

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