Light emitting material, ink composition, and display panel

Abstract

The embodiment of the present application discloses a luminescent material, an ink composition and a display panel. The luminescent material comprises a first compound with a lower ΔEST (about 0.09 eV), and the first compound belongs to a thermally activated delayed fluorescence material. The luminescent material has good solution processing performance, can be prepared into an ink composition, can realize printing film forming, and meets the demand of large-scale industrial production. The display panel comprises a green light emitting unit, the green light emitting unit comprises the luminescent material, or the green light emitting unit is prepared by using the ink composition, and the luminescent efficiency of the green light emitting unit can be improved.

Description

Technical Field

[0001] This application relates to the field of display technology, and more particularly to a luminescent material, an ink composition, and a display panel. Background Technology

[0002] With the development of display technology, display panels based on organic light-emitting diodes (OLEDs) have become a major research direction in display panels due to their advantages such as self-illumination and low energy consumption. OLEDs use organic compounds as light-emitting materials and have advantages such as high photoelectric efficiency, fast response, and molecular flexibility.

[0003] Thermally activated delayed fluorescence (TADF) is a novel type of organic light-emitting material with advantages such as low cost and high efficiency. TADF is considered a third-generation organic light-emitting material. TADF achieves a theoretically 100% internal quantum efficiency through reverse intersystem crossing. The luminescence of TADF can be divided into two parts: one is the transient fluorescence process induced by 25% of singlet excitons; the other is the delayed fluorescence process induced by 75% of triplet excitons through reverse intersystem crossing.

[0004] After more than a decade of development, TADF materials have become more diverse and have shown great potential for application. However, the luminous efficiency of OLEDs containing TADF materials still needs further improvement. Therefore, providing a novel TADF material is of great significance. Summary of the Invention

[0005] This application provides a luminescent material, an ink composition, and a display panel to improve the luminescent efficiency of the luminescent material.

[0006] In a first aspect, this application provides a luminescent material, comprising a first compound with the structure shown in general formula (Ⅰ) below:

[0007]

[0008] In general formula (I), R1 and R2 are independently selected from straight-chain alkyl or branched alkyl groups having 3 to 8 carbon atoms.

[0009] Optionally, R1 and R2 are independently selected from straight-chain alkyl or branched alkyl groups having 3 to 5 carbon atoms.

[0010] Optionally, the first compound has a structural formula of any one of the following formulas (1.1) to (1.3):

[0011]

[0012] Optionally, the luminescent material further includes a second compound selected from one or more of 4,4'-bis(9-carbazole)biphenyl, 2,6-bis[3-(9H-carbazole-9-yl)phenyl]pyridine, 3,5-bis(3-(9H-carbazole-9-yl)phenyl)pyridine, polyacetylene, and polythiophene compounds.

[0013] Optionally, in the luminescent material, the mass ratio of the second compound to the first compound is 1:(0.04 to 0.1).

[0014] In a second aspect, this application provides an ink composition comprising at least one luminescent material as described in any of the first aspects, and at least one organic solvent.

[0015] Optionally, the organic solvent, calculated by mass parts, includes: 10 to 40 parts of ethyl 2-cyano-2-methylpropionate, 100 to 200 parts of ethyl cyanoacetate, 250 to 400 parts of ethyl isobutyrylate, and 30 to 70 parts of allyl acetoacetate.

[0016] Optionally, the first compound accounts for 1.1% to 5.3% of the total mass of the ink composition.

[0017] Thirdly, this application provides a display panel including a green light-emitting unit; the green light-emitting unit includes a light-emitting material as described in any of the first aspects, or is prepared using an ink composition as described in any of the second aspects.

[0018] Optionally, the green light-emitting unit includes:

[0019] Anode and cathode arranged opposite each other;

[0020] A light-emitting layer is disposed between the anode and the cathode;

[0021] An electronic functional layer is disposed between the cathode and the light-emitting layer; and

[0022] A hole-functional layer is disposed between the anode and the light-emitting layer;

[0023] The material of the light-emitting layer includes any of the light-emitting materials described in the first aspect, or the light-emitting layer is formed using any of the ink compositions described in the second aspect.

[0024] Beneficial effects: The luminescent material provided in this application includes a first compound with a low ΔEST (around 0.09 eV). The first compound belongs to thermally activated delayed fluorescence materials. The luminescent material has good solution processing properties, can be formulated into an ink composition, and can be printed into a film to meet the needs of large-scale industrial production. The display panel includes a green luminescent unit, which includes the luminescent material, or the green luminescent unit can be prepared using the ink composition, which can improve the luminous efficiency of the green luminescent unit by up to 50%. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of a green organic light-emitting diode provided in an embodiment of this application.

[0027] Figure 2 The first compound is shown in the nuclear magnetic resonance spectrum of the first compound prepared in Example 1.

[0028] Figure 3 The nuclear magnetic resonance spectrum of the third compound obtained in Example 1 of the first compound;

[0029] Figure 4 The first compound is shown in the nuclear magnetic resonance spectrum of the first compound prepared in Example 2.

[0030] Figure 5 The nuclear magnetic resonance spectrum of the third compound obtained in Example 2 of the first compound;

[0031] Figure 6 The first compound is shown in the nuclear magnetic resonance spectrum of the first compound prepared in Example 3.

[0032] Figure 7 The NMR spectrum of the third compound prepared in Example 3 of the first compound.

[0033] Figure 8 This is a schematic diagram of another green organic light-emitting diode provided in an embodiment of this application.

[0034] Figure label:

[0035] 10: Green organic light-emitting diode, 11: Anode, 12: Cathode, 13: Light-emitting layer, 14: Electron functional layer, 15: Hole functional layer, 141: Hole blocking layer, 142: Electron transport layer, 151: Hole injection layer, 152: Hole transport layer. Detailed Implementation

[0036] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0038] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0039] In the description of this application, the term "comprising" means "including but not limited to".

[0040] The term "at least one" means one or more, and "multiple" means two or more. The terms "at least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of a single or multiple items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can be expressed as: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0041] The term "and / or" encompasses any one of two or more of the listed items, as well as any and all combinations of the listed items. These combinations include any two listed items, any number of listed items, or a combination of all listed items. For example, "A and / or B" includes three parallel solutions: A, B, and A+B. Similarly, the technical solution "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (i.e., all connected by "logical OR"), any and all combinations of A, B, C, and D, including combinations of any two or three of A, B, C, and D, and combinations of all four of A, B, C, and D (i.e., all connected by "logical AND").

[0042] The terms "length," "width," "thickness," "upper," and "lower," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In the description of this application, "a plurality of" means two or more, unless otherwise expressly and specifically defined.

[0043] The term "alkyl" refers to a type of chain-like organic group containing only carbon and hydrogen atoms, which is a hydrocarbon group formed by removing one hydrogen atom from an alkane molecule.

[0044] The term "inert gas" refers to a class of chemically inert gases, including but not limited to one or more of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and nitrogen (N2). In some embodiments of this application, N2 is used as an example of an inert gas.

[0045] This application provides a luminescent material, comprising a first compound with the structure shown in general formula (Ⅰ) below:

[0046]

[0047] In general formula (I), R1 and R2 are independently selected from straight-chain alkyl or branched alkyl groups having 3 to 8 carbon atoms. For example, R1 and R2 are independently selected from straight-chain alkyl or branched alkyl groups having 3, 4, 5, 6, 7 or 8 carbon atoms, such as n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, 2-ethylbutyl, 3-methylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, 1-methylhexyl, 2-ethylhexyl, n-heptyl, 1-methylheptyl, n-octyl or tert-octyl.

[0048] In some embodiments of this application, the first compound has a structural formula of any one of the following formulas (1.1) to (1.3):

[0049]

[0050] It should be noted that the first compound with the structure shown in general formula (I) has a low ΔEST. For example, the ΔEST of the first compounds with the structures shown in formulas (1.1) to (1.3) is about 0.09 eV, which belongs to thermally active delayed fluorescence materials. Furthermore, the first compound with the structure shown in general formula (I) has good solution processing performance, can be formulated into ink compositions, and can be printed into films to meet the needs of large-scale industrial production.

[0051] This application also provides a method for preparing a first compound, which can be used to prepare any first compound with the structure shown in general formula (Ⅰ), comprising the following steps:

[0052] S1. Provide a first intermediate and a second intermediate;

[0053] S2. Under an environment of 20℃~30℃, the second intermediate, the third compound, and sodium hydride (NaH) are dispersed in tetrahydrofuran and reacted for 3h~5h, wherein the molar ratio of the third compound: the second intermediate: sodium hydride is 1:(1.0~1.3):(1.9~2.1). After the reaction is completed, deionized water is added to the obtained first reaction product to hydrolyze the excess NaH, and then ethanol is added to precipitate the precipitate. The precipitate is collected by filtration. The first solid is washed with water and filtered to obtain the second solid. The second solid is recrystallized with ethyl acetate at least once to obtain the fourth compound.

[0054] S3. Dissolve the fourth compound and the first intermediate in anhydrous toluene to obtain a first solution. Then, add sodium tert-butoxide, bis(di-benzylacetone)palladium, and tri-tert-butylphosphine solution (solvent is toluene, and the mass percentage of tri-tert-butylphosphine is 10%) to the first solution. Under an inert gas atmosphere, maintain the temperature at 100℃~120℃ and stir and reflux for 11h~13h. The molar ratio of the fourth compound: the first intermediate: sodium tert-butoxide: bis(benzylacetone)palladium: tributylphosphine is 1:(1.1~1.3):(0.9~1.1):(0.15~0.18):(0.04~0.06). After the reaction is completed, cool to room temperature. The obtained second reaction product is subjected to solvent removal and purification column purification treatment to obtain the first compound.

[0055] In step S1, the preparation method of the first intermediate includes the following steps:

[0056] S101, 23.6 g of 1,3-dibromobenzene, 22.6 g of phenol, 39.1 g of cesium carbonate (Cs2CO3) and 1.43 g of copper bromide (CuBr) were mixed and stirred under reflux at 160 °C for 10 h. After the reaction was completed, the mixture was cooled to room temperature. The obtained third reaction product was subjected to solvent removal and purification by a purification column to obtain the fifth compound. The reaction yield was 93%.

[0057] S102. First, dissolve 13.1g of the fifth compound in 60mL of anhydrous tetrahydrofuran, then cool to -70℃ using hydrazine. Add 20mL of a 2.5mol / L n-butyllithium solution (cyclohexane) to obtain the first reaction system. Heat the first reaction system to 0℃ and stir for 4 hours under an inert gas atmosphere to obtain the fourth reaction product. Then, at -40℃, add 50mL of a 1mol / L boron tribromide solution (dichloromethane) to the fourth reaction product to obtain the second reaction system. The second reaction system was heated to 40°C and stirred for 12 hours under an inert gas atmosphere to obtain the fifth reaction product. Then, 25 mL of a 2 mol / L diisopropylethylamine solution (N-methylpyrrolidone as solvent) was added to the fifth reaction product at 0°C to obtain the third reaction system. The third reaction system was heated to 120°C and reacted for 4 hours to obtain the sixth reaction product. The sixth reaction product was rotary evaporated to remove the solvent, filtered to obtain the crude product, and purified by a purification column to obtain the sixth compound. The reaction yield was 56.8%.

[0058] S103. At 25°C, 1.0 equivalent of the sixth compound and 1.2 equivalent of N-bromosuccinimide were mixed and reacted for 4 hours to obtain the seventh reaction product. The seventh reaction product was rotary evaporated to remove the solvent, and then filtered, dried and recrystallized in sequence to obtain the first intermediate. The reaction yield was 87.6%.

[0059] The reaction involved in step S101 is shown in equation (2.1), and the reaction product shown in equation (2.1) is the fifth compound:

[0060]

[0061] The reaction involved in step S102 is shown in equation (2.2) below, and the reaction product shown in equation (2.2) is the sixth compound:

[0062]

[0063] The reaction involved in step S103 is shown in equation (2.3) below, and the reaction product shown in equation (2.3) is the first intermediate:

[0064]

[0065] The preparation method of the second intermediate includes the following steps: 28.56 g of p-chloroiodobenzene, 20.2 g of diphenylphosphine oxide, 2.67 g of bis(1,5-cyclooctadiene)nickel (Ni(Cod)2), 2.67 g of 4,4-di-tert-butylbipyridine (CAS No. 72914-19-3), 0.384 g of iridium (catalyst) and 65.2 g of Cs2CO3 are dispersed in 150 mL of anhydrous methanol to obtain a reaction system. The reaction system is stirred and reacted for 24 h at room temperature and under the illumination of a 3W blue LED. After the reaction is completed, the reaction product is subjected to vacuum distillation, drying and purification column purification to obtain the second intermediate with a reaction yield of 65%.

[0066] The second intermediate has the structure shown in formula (Ⅱ):

[0067]

[0068] Continuing with step S2, the third compound has the structure shown in general formula (Ⅲ):

[0069]

[0070] The reaction involved in step S2 is shown in equation (2.4) below, and the reaction product shown in equation (2.4) is the fourth compound:

[0071]

[0072] The reaction involved in step S3 is shown in equation (2.5) below:

[0073]

[0074] To further improve the luminescence efficiency of the luminescent material, in some embodiments of this application, the luminescent material further includes a second compound selected from one or more of 4,4'-bis(9-carbazole)biphenyl, 2,6-bis[3-(9H-carbazole-9-yl)phenyl]pyridine, 3,5-bis(3-(9H-carbazole-9-yl)phenyl)pyridine, polyacetylene, and polythiophene compounds.

[0075] In order to further improve the luminescent performance of the luminescent material, in some embodiments of this application, the mass ratio of the second compound to the first compound is 1:(0.04 to 0.1), for example, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1 or any value between the two aforementioned values.

[0076] In some embodiments of this application, the luminescent host material is selected from one or more of the following: 4,4'-bis(9-carbazole)biphenyl (abbreviated as CBP, CAS No. 58328-31-7), 2,6-bis[3-(9H-carbazole-9-yl)phenyl]pyridine (CAS No. 1013405-24-7), 3,5-bis(3-(9H-carbazole-9-yl)phenyl)pyridine (CAS No. 1013405-25-8), polyacetylene, and polythiophene compounds.

[0077] This application also provides an ink composition comprising any of the luminescent materials described above, and at least one organic solvent.

[0078] In order to further improve both the printing performance and the luminescence performance of the ink composition, in some embodiments of this application, the ink composition includes one or more of the organic compounds shown in formula (1.1), formula (1.2), and formula (1.3).

[0079] To further improve the stability of the ink composition, in some embodiments of this application, the organic solvents, calculated by weight, include: 10 to 40 parts of ethyl 2-cyano-2-methylpropionate, 100 to 200 parts of ethyl cyanoacetate, 250 to 400 parts of ethyl isobutyrylate, and 30 to 70 parts of allyl acetoacetate. Ethyl isobutyrylate, as the main solvent component, has moderate viscosity and good solubility, and can dissolve most organic materials; ethyl cyanoacetate is a high-boiling-point solvent with good printing volatility and film-forming properties; ethyl 2-cyano-2-methylpropionate is a high-boiling-point solvent, which can improve the solvent boiling point of the ink composition and enhance its stability; allyl acetoacetate is used to improve the viscosity and surface tension of the ink composition. Understandably, printing processes place stringent requirements on the stability of ink compositions. The organic solvents in ink compositions need to meet various requirements, including solubility, boiling point, viscosity, and surface tension. Generally, a single organic solvent is unlikely to meet these performance requirements. Therefore, compared to selecting any one, two, or three of the organic solvents in an ink composition from ethyl 2-cyano-2-methylpropionate, ethyl cyanoacetate, ethyl isobutyrylate, and allyl acetoacetate, a combination of these organic solvents can improve the quality of the printed film.

[0080] To further enhance the luminescent properties of the ink composition, in some embodiments of this application, the mass of the first compound accounts for 1.1% to 5.3% of the total mass of the ink composition, for example, it can be 1.1%, 2%, 3%, 4%, 5.3% or any value between the two aforementioned percentages.

[0081] This application embodiment also provides a display panel, the display panel including a green light-emitting unit; the green light-emitting unit includes any of the light-emitting materials described above, or the green light-emitting unit is prepared using any of the ink compositions described above, which can improve the luminous efficiency of the green light-emitting unit.

[0082] It is understood that, in addition to green light-emitting units, display panels may also include other types of light-emitting units, including but not limited to red light-emitting units, blue light-emitting units, etc. Display panels may also include other conventional structural components, such as substrates, driving circuit layers, and encapsulation layers. The substrate material may be, for example, a rigid material such as glass or a flexible material such as polyimide; the driving circuit layer acts as the switch for the light-emitting units, and may include, for example, thin-film transistors.

[0083] In some embodiments of this application, the green light-emitting unit is a green organic light-emitting diode (OLED). The green OLED has a forward-facing or inverted structure, and its light-emitting mode is either top-emitting or bottom-emitting, such as... Figure 1 As shown, the green organic light-emitting diode 10 includes an anode 11, a cathode 12, a light-emitting layer 13, an electronic functional layer 14, and a hole functional layer 15. The anode 11 and cathode 12 are disposed opposite each other; the light-emitting layer 13 is disposed between the anode 11 and cathode 12, and the material of the light-emitting layer includes any of the light-emitting materials described above, or is formed using any of the ink compositions described above; the electronic functional layer 14 is disposed between the cathode 12 and the light-emitting layer 13; and the hole functional layer 15 is disposed between the anode 11 and the light-emitting layer 13.

[0084] To balance improving the photoelectric performance of the green organic light-emitting diode 10 with controlling manufacturing costs, in some embodiments of this application, the materials of the anode 11 and the cathode 12 are independently selected from one or more of metals, carbon materials, and metal oxides, and / or the thicknesses of the anode 11 and the cathode 12 are 20 nm to 300 nm, respectively. The metals include, but are not limited to, one or more of Al, Ag, Cu, Mo, Au, Ba, Pt, Ca, Ir, Ni, and Mg; the carbon materials include, but are not limited to, one or more of graphite, carbon nanotubes, graphene, and carbon fibers; the metal oxides can be doped or undoped, and the doped metal oxides include, but are not limited to, one or more of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), and magnesium-doped zinc oxide (MZO), while the undoped metal oxides include, but are not limited to, one or more of SnO2, ZnO, and In2O3. In addition, at least one of the anode 11 and the cathode 12 can be a composite electrode with a sandwich-like structure. The upper and lower layers are made of doped or undoped transparent metal oxides, respectively, and the middle layer is made of metal, such as one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2.

[0085] The electronic functional layer 14 can be a single-layer or multi-layer structure, and its thickness is, for example, 10 nm to 200 nm. The electronic functional layer 14 may include one or more of an electron injection layer, an electron transport layer, and a hole blocking layer. For an electronic functional layer 14 including an electron injection layer, an electron transport layer, and a hole blocking layer, the electron transport layer is located between the electron injection layer and the hole blocking layer, and the electron injection layer is closer to the cathode than the hole blocking layer, while the hole blocking layer is closer to the light-emitting layer than the electron injection layer.

[0086] The materials used for the electron injection layer, electron transport layer, and hole blocking layer can be conventional materials in the art. The electron injection layer material includes, but is not limited to, one or more of LiF, MgP, MgF2, and Al2O3. The electron transport layer material includes, but is not limited to, ZnO, TiO2, 2-(4'-tert-butylphenyl)-5-(4'-biphenyl)-1,3,4-oxadiazole, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 1,3,5-tris((3-pyridyl)-3-phenyl)benzene, 2,9-dimethyl-4,7-diphenyl-1,10-o-diazaphenanthroline, 4,7-diphenyl-1,10-o-diazaphenanthroline, 3-(biphenyl-4-yl)-5 One or more of 1,3,5-triazole, tris(8-hydroxyquinoline)aluminum, bis(2-methyl-8-hydroxyquinoline-N1,O8)-1,1'-biphenyl-4-hydroxy)aluminum, and 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine. The hole-blocking layer material includes, but is not limited to, one or more of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene and NaF.

[0087] The hole functional layer 15 can be a single-layer or multi-layer structure, and its thickness is, for example, 10 nm to 200 nm. The hole functional layer 15 may include one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. For a hole functional layer 15 including a hole injection layer, a hole transport layer, and an electron blocking layer, the hole transport layer is located between the hole injection layer and the electron blocking layer, and the hole injection layer is closer to the cathode than the electron blocking layer, while the electron blocking layer is closer to the light-emitting layer than the hole injection layer.

[0088] The materials used for the hole injection layer, hole transport layer, and electron blocking layer can be conventional materials in the art. The materials for the hole injection layer include, but are not limited to, copper phthalocyanine, titanium phthalocyanine, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, and 4,4',4”-tris[2-naphthylphenylamino]triphenylamine. Materials for the hole transport layer include, but are not limited to, poly(3,4-vinyldioxythiophene): poly(styrene sulfonic acid), 3-hexyl-substituted polythiophene, poly(9-vinylcarbazole), 4,4'-bis(9-carbazole)biphenyl, poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-( [4-sec-butylphenyl)diphenylamine], poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(p-butylphenyl))diphenylamine)], poly(N,N'-di(4-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine-CO-9,9-dioctylfluorene), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, 4,4',4”-tris(carbazole-9-yl) Triphenylamine, 4,4',4'-tris(2-naphthylphenylamino)triphenylamine, N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine, N,N'-bis(3-methylphenyl)-N,N One or more of the following: '-diphenyl-9,9-spirodifluorene-2,7-diamine, N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirodi[9H-fluorene]-2,7-diamine, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], and 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene. The electron blocking layer material includes, but is not limited to, aluminum nitride.

[0089] This application embodiment also provides a display device, which includes any of the display panels described above. The display device provided in this application embodiment can be at least one of a smartphone, tablet computer, mobile phone, video phone, e-book reader, laptop PC, netbook computer, workstation, server, personal digital assistant, portable multimedia player, MP3 player, mobile medical device, camera, game console, digital camera, car navigation system, electronic billboard, ATM, smart bracelet, smartwatch, virtual reality (VR) device, or wearable device.

[0090] The technical solution and effects of this application will be described in detail below through specific embodiments, comparative examples, and experimental examples. The following embodiments are only some embodiments of this application and are not intended to limit this application in any specific way. The preparation method of the first intermediate is carried out according to steps S101 to S103, and the preparation method of the second intermediate is carried out as described above.

[0091] First Compound Example 1

[0092] This embodiment provides a first compound and its preparation method. The first compound has the structure shown in formula (1.1), and the preparation method of the first compound includes the following steps:

[0093] S1.1 At 25°C, 15.6 g of the second intermediate, 22.08 g of the third compound shown in formula (3.1) and 2.4 g of sodium hydride (NaH) were dispersed in 80 mL of tetrahydrofuran and reacted for 4 h. After the reaction was completed, deionized water was added to the obtained first reaction product to hydrolyze the excess NaH, and then ethanol was added to precipitate the precipitate. The precipitate was collected by filtration. The first solid was washed with water and filtered to obtain the second solid. The second solid was recrystallized with ethyl acetate at least once to obtain the fourth compound.

[0094] S1.2 12.89 g of the fourth compound and 8.35 g of the first intermediate were dissolved in 75 mL of anhydrous toluene to obtain a first solution. Then, 1.92 g of sodium tert-butoxide, 1.96 g of bis(di-tert-butylacetone)palladium and 2 mL of tri-tert-butylphosphine solution (solvent is toluene, and the mass percentage of tri-tert-butylphosphine is 10%) were added to the first solution. The reaction was carried out under nitrogen protection and stirred under reflux at 110 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature. The reaction product was then subjected to solvent removal and purification column purification to obtain a solid material.

[0095] The solid material obtained in step S1.2 was subjected to NMR identification, and the NMR spectrum is shown below. Figure 2 As shown, the solid material is the first compound with the structure shown in formula (1.1).

[0096] The third compound represented by formula (3.1) is:

[0097]

[0098] The synthetic route for the third compound shown in equation (3.1) is as follows:

[0099]

[0100] The synthesis of intermediate compound 3.1-A includes the following steps: at room temperature, 0.2 mol of 4-tert-butylbromobenzene is dissolved in 40 mL of concentrated sulfuric acid to obtain a solution. Under stirring, 0.2 mol of HNO3 is slowly added to the solution to obtain a reaction system. The reaction system is kept at 50 °C for 6 h, and the reaction is monitored by LC-MS. After the reaction is completed, the reaction product is first neutralized, then the reaction product is extracted with dichloromethane, dried with Na2SO4 and concentrated under vacuum, and passed through silica gel to obtain 46.11 g of intermediate compound 3.1-A.

[0101] The synthesis of intermediate compound 3.1-B included the following steps: 0.2 mol of 4-tert-butylbromobenzene, 0.22 mmol of 2-nitrophenylboronic acid, 0.4 mol of Na₂CO₃, and 0.002 mol of Pd(pph₃)₄ were added to a 1000 mL two-necked flask. A mixed solution of dioxane and water (obtained by mixing 420 mL of dioxane and 70 mL of water) was then added. The mixture was heated to 100 °C and reacted for 8 h, with the reaction monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation, followed by separation by water washing and then separation of the product by dry column chromatography to obtain 43.45 g of intermediate compound 3.1-B.

[0102] The synthesis of intermediate compound 3.1-C includes the following steps: 0.15 mol of intermediate compound 3.1-B and 150 mL of triethyl phosphite are added to a dry two-necked flask, the mixture is heated to 160 °C and reacted for 8 h. The reaction product is then subjected to vacuum distillation and silica gel separation to obtain 27.86 g of intermediate compound 3.1-C.

[0103] The synthesis of intermediate compound 3.1-D includes the following steps: 0.1 mol of compound 3.1-C, 0.12 mol of N-bromosuccinimide, and 80 mL of tetrahydrofuran are added to a dry flask, mixed, and then reacted at room temperature for 4 h; after the reaction is completed, the solvent of the reaction product is removed by rotary evaporation, and then the product is subjected to filtration, drying, and recrystallization to obtain 26.88 g of intermediate compound 3.1-D.

[0104] The synthesis of intermediate compound 3.1-E included the following steps: 0.08 mol of intermediate compound 3.1-D, 0.12 mol of bis-pinacol boronic acid ester, 0.16 mol of potassium acetate, 0.008 mol of PdCl2 (dppf), and 300 mL of dimethyl sulfoxide were added to a 1000 mL three-necked flask. The mixture was heated to 80 °C under nitrogen atmosphere and reacted for 4 h. The reaction was monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation. Then, the product was washed with water and extracted with dichloromethane. Finally, the product was separated by dry column chromatography to obtain 21.79 g of intermediate compound 3.1-E.

[0105] The synthesis of intermediate compound 3.1-F included the following steps: 0.05 mol of intermediate compound 3.1-E, 0.55 mol of intermediate compound 3.1-A, 0.1 mol of Na₂CO₃, and 0.002 mol of Pd(pph₃)₄ were added to a 500 mL double-necked flask. A mixed solution of dioxane and water (obtained by mixing 210 mL of dioxane and 35 mL of water) was then added. The mixture was heated to 110 °C and reacted for 8 h, with the reaction monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation, followed by separation by water washing and then separation of the product by dry column chromatography to obtain 16.25 g of intermediate compound 3.1-F.

[0106] The synthesis of the third compound shown in formula (3.1) includes the following steps: 0.03 mol of intermediate compound 3.1-F and 100 mL of triethyl phosphite are added to a dry two-necked flask. After mixing, the mixture is heated to 160 °C and reacted for 8 h. The reaction product is then subjected to vacuum distillation and silica gel separation to obtain 9.29 g of the third compound with the structure shown in formula (3.1). The NMR spectrum of the third compound with the structure shown in formula (3.1) is shown below. Figure 3 As shown.

[0107] First Compound Example 2

[0108] This embodiment provides a first compound and its preparation method. The first compound has the structure shown in formula (1.2). Compared with the preparation method of the first compound in Example 1, the difference in the preparation method of the first compound in this embodiment is that the "first compound shown in formula (3.1)" in step S1.1 is replaced with "the first compound shown in formula (3.2)".

[0109] The obtained solid material was identified by nuclear magnetic resonance (NMR), and the NMR spectrum is as follows: Figure 4 As shown, the solid material is an organic compound with the structure shown in formula (1.2).

[0110] The first compound represented by formula (3.2) is:

[0111]

[0112] The synthetic route for the third compound shown in equation (3.2) is as follows:

[0113]

[0114] The synthesis of intermediate compound 3.2-A includes the following steps: at room temperature, 0.2 mol of 4-tert-pentylbromobenzene is dissolved in 40 mL of concentrated sulfuric acid to obtain a solution. Under stirring, 0.2 mol of HNO3 is slowly added to the solution to obtain a reaction system. The reaction system is kept at 50 °C for 6 h, and the reaction is monitored by LC-MS. After the reaction is completed, the reaction product is first neutralized, then the reaction product is extracted with dichloromethane, dried with Na2SO4 and concentrated under vacuum, and passed through silica gel to obtain 46.35 g of intermediate compound 3.2-A.

[0115] The synthesis of intermediate compound 3.2-B included the following steps: 0.2 mol of 4-tert-amylbromobenzene, 0.22 mmol of 2-nitrophenylboronic acid, 0.4 mol of Na₂CO₃, and 0.002 mol of Pd(pph₃)₄ were added to a 1000 mL two-necked flask. A mixed solution of dioxane and water (420 mL of dioxane and 70 mL of water) was then added. The mixture was heated to 100 °C and reacted for 8 h, with the reaction monitored by LC-MS. After the reaction was complete, the solvent of the reaction product was removed by rotary evaporation, followed by separation by water washing and then separation of the product by dry column chromatography to obtain 43.69 g of intermediate compound 3.2-B.

[0116] The synthesis of intermediate compound 3.2-C includes the following steps: 0.15 mol of intermediate compound 3.2-B and 150 mL of triethyl phosphite are added to a dry two-necked flask, the mixture is heated to 160 °C and reacted for 8 h. The reaction product is then subjected to vacuum distillation and silica gel separation to obtain 28.09 g of intermediate compound 3.2-C.

[0117] The synthesis of intermediate compound 3.2-D includes the following steps: 0.1 mol of compound 3.2-C, 0.12 mol of N-bromosuccinimide, and 80 mL of tetrahydrofuran are added to a dry flask, mixed, and then reacted at room temperature for 4 h; after the reaction is completed, the solvent of the reaction product is removed by rotary evaporation, and then the product is subjected to filtration, drying, and recrystallization to obtain 27.13 g of intermediate compound 3.2-D.

[0118] The synthesis of intermediate compound 3.2-E included the following steps: 0.08 mol of compound 3.2-D, 0.12 mol of bis-pinacol boronic acid ester, 0.16 mol of potassium acetate, 0.008 mol of PdCl2 (dppf), and 300 mL of dimethyl sulfoxide were added to a 1000 mL three-necked flask. The mixture was heated to 80 °C under nitrogen atmosphere and reacted for 4 h. The reaction was monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation. Then, the product was washed with water and extracted with dichloromethane. Finally, the product was separated by dry column chromatography to obtain 22.0 g of intermediate compound 3.2-E.

[0119] The synthesis of intermediate compound 3.2-F included the following steps: 0.05 mol of intermediate compound 3.2-E, 0.55 mol of intermediate compound 3.2-A, 0.1 mol of Na₂CO₃, and 0.002 mol of Pd(pph₃)₄ were added to a 500 mL double-necked flask. A mixed solution of dioxane and water (obtained by mixing 210 mL of dioxane and 35 mL of water) was then added. The mixture was heated to 110 °C and reacted for 8 h, with the reaction monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation, followed by separation by water washing and then separation of the product by dry column chromatography to obtain 16.48 g of intermediate compound 3.2-F.

[0120] The synthesis of the third compound shown in formula (3.2) includes the following steps: 0.03 mol of intermediate compound 3.2-F and 100 mL of triethyl phosphite are added to a dry two-necked flask. After mixing, the mixture is heated to 160 °C and reacted for 8 h. The reaction product is then subjected to vacuum distillation and silica gel separation to obtain 9.52 g of the third compound with the structure shown in formula (3.2). The NMR spectrum of the third compound with the structure shown in formula (3.2) is shown below. Figure 5 As shown.

[0121] First Compound Example 3

[0122] This embodiment provides a first compound and its preparation method. The organic compound has the structure shown in formula (1.3). Compared with the preparation method of the first compound in Example 1, the difference in the preparation method of the first compound in this embodiment is that the "first compound shown in formula (3.1)" in step S1.1 is replaced with "the first compound shown in formula (3.3)".

[0123] The obtained solid material was identified by nuclear magnetic resonance (NMR), and the NMR spectrum is as follows: Figure 6 As shown, the solid material is an organic compound with the structure shown in formula (1.3).

[0124] The first compound represented by formula (3.3) is:

[0125]

[0126] The synthetic route for the third compound shown in equation (3.3) is as follows:

[0127]

[0128] The synthesis of intermediate compound 3.3-A includes the following steps: at room temperature, 0.2 mol of 4-isopropylbromobenzene is dissolved in 40 mL of concentrated sulfuric acid to obtain a solution. Under stirring, 0.2 mol of HNO3 is slowly added to the solution to obtain a reaction system. The reaction system is kept at 50 °C for 6 h, and the reaction is monitored by LC-MS. After the reaction is completed, the reaction product is first neutralized, then the reaction product is extracted with dichloromethane, dried with Na2SO4 and concentrated under vacuum, and passed through silica gel to obtain 45.88 g of intermediate compound 3.3-A.

[0129] The synthesis of intermediate compound 3.3-B included the following steps: 0.2 mol of 4-isopropylbromobenzene, 0.22 mmol of 2-nitrophenylboronic acid, 0.4 mol of Na₂CO₃, and 0.002 mol of Pd(pph₃)₄ were added to a 1000 mL two-necked flask. A mixed solution of dioxane and water (420 mL of dioxane and 70 mL of water) was then added. The mixture was heated to 100 °C and reacted for 8 h, with the reaction monitored by LC-MS. After the reaction was complete, the solvent of the reaction product was removed by rotary evaporation, followed by separation by water washing and then separation of the product by dry column chromatography to obtain 43.16 g of intermediate compound 3.3-B.

[0130] The synthesis of intermediate compound 3.3-C includes the following steps: 0.15 mol of intermediate compound 3.3-B and 150 mL of triethyl phosphite are added to a dry two-necked flask, the mixture is heated to 160 °C and reacted for 8 h. The reaction product is then subjected to vacuum distillation and silica gel separation to obtain 27.59 g of intermediate compound 3.3-C.

[0131] The synthesis of intermediate compound 3.3-D includes the following steps: 0.1 mol of compound 3.3-C, 0.12 mol of N-bromosuccinimide, and 80 mL of tetrahydrofuran are added to a dry flask, mixed, and then reacted at room temperature for 4 h; after the reaction is completed, the solvent of the reaction product is removed by rotary evaporation, and then the product is subjected to filtration, drying, and recrystallization to obtain 26.63 g of intermediate compound 3.3-D.

[0132] The synthesis of intermediate compound 3.3-E included the following steps: 0.08 mol of intermediate compound 3.3-D, 0.12 mol of dipinacol boronic acid ester, 0.16 mol of potassium acetate, 0.008 mol of PdCl2 (dppf), and 300 mL of dimethyl sulfoxide were added to a 1000 mL three-necked flask. The mixture was heated to 80 °C under nitrogen atmosphere and reacted for 4 h. The reaction was monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation. Then, the product was washed with water and extracted with dichloromethane. Finally, the product was separated by dry column chromatography to obtain 21.54 g of intermediate compound 3.3-E.

[0133] The synthesis of intermediate compound 3.3-F included the following steps: 0.05 mol of intermediate compound 3.3-E, 0.55 mol of intermediate compound 3.3-A, 0.1 mol of Na2CO3, and 0.002 mol of Pd(pph3)4 were added to a 500 mL double-necked flask. A mixed solution of dioxane and water (obtained by mixing 210 mL of dioxane and 35 mL of water) was then added. The mixture was heated to 110 °C and reacted for 8 h, with the reaction monitored by LC-MS. After the reaction was completed, the solvent of the reaction product was removed by rotary evaporation, followed by separation by water washing and then separation of the product by dry column chromatography to obtain 16.0 g of intermediate compound 3.3-F.

[0134] The synthesis of the third compound with the structure shown in formula (3.3) includes the following steps: 0.03 mol of intermediate compound 3.3-F and 100 mL of triethyl phosphite are added to a dry two-necked flask. After mixing, the mixture is heated to 160 °C and reacted for 8 h. The reaction product is then subjected to vacuum distillation and silica gel separation to obtain 9.12 g of the third compound with the structure shown in formula (3.3). The NMR spectrum of the third compound with the structure shown in formula (3.3) is shown below. Figure 7 As shown.

[0135] Ink Composition Example 1

[0136] This embodiment provides an ink composition comprising a first compound having the structure shown in formula (1.1), 4,4'-bis(9-carbazole)biphenyl (CAS No. 58328-31-7), and an organic solvent. The mass ratio of 4,4'-bis(9-carbazole)biphenyl to the first compound having the structure shown in formula (1.1) is 1:0.07, and the mass of the first compound having the structure shown in formula (1.1) accounts for 5% of the total mass of the ink composition. The organic solvent, by mass parts, comprises 20 parts of ethyl 2-cyano-2-methylpropionate, 110 parts of ethyl cyanoacetate, 300 parts of ethyl isobutyrylate, and 40 parts of allyl acetoacetate.

[0137] Ink Composition Example 2

[0138] This embodiment provides an ink composition. Compared with the ink composition in Example 1, the difference in this embodiment is that "the first compound having the structure shown in formula (1.1)" is replaced with "the first compound having the structure shown in formula (1.2)".

[0139] Ink Composition Example 3

[0140] This embodiment provides an ink composition. Compared with the ink composition in Example 1, the difference in this embodiment is that "the first compound having the structure shown in formula (1.1)" is replaced with "the first compound having the structure shown in formula (1.3)".

[0141] Ink Composition Example 4

[0142] This embodiment provides an ink composition comprising a first compound having the structure shown in formula (1.1), a first compound having the structure shown in formula (1.2), 4,4'-bis(9-carbazole)biphenyl, and an organic solvent. The mass ratio of the first compound having the structure shown in formula (1.1) to the first compound having the structure shown in formula (1.2) is 1:1. The total mass of the first compound having the structure shown in formula (1.1) and the first compound having the structure shown in formula (1.2) is a first mass, which is 5% of the total mass of the ink composition. The mass ratio of 4,4'-bis(9-carbazole)biphenyl:the first compound having the structure shown in formula (1.1):the first compound having the structure shown in formula (1.2) is 1:0.035:0.035. The organic solvent is the same as in ink composition example 1.

[0143] Ink Composition Example 5

[0144] This embodiment provides an ink composition. Compared with the ink composition in Ink Composition Example 1, the difference in this embodiment is that "the first mass is 5% of the total mass of the ink composition" is replaced with "the first mass is 8% of the total mass of the ink composition".

[0145] Ink Composition Example 6

[0146] This embodiment provides an ink composition. Compared with the ink composition in Example 1, the difference in this embodiment is that the organic solvent is replaced with "the organic solvent is composed of 20 parts of 2-cyano-2-methylpropionic acid ethyl ester, 110 parts of ethyl cyanoacetate and 300 parts of ethyl isobutyrylate, calculated by mass parts".

[0147] Comparative Example 1 of Ink Compositions

[0148] This comparative example provides an ink composition that differs from the ink composition in Example 1 in that the "organic compound having the structure shown in Formula (1.1)" is replaced with "tris(2-phenylpyridine)iridium (CAS No. 94928-86-6)".

[0149] Comparative Example 2 of Ink Compositions

[0150] This comparative example provides an ink composition that differs from the ink composition in Example 1 in that: "an organic compound having the structure shown in formula (1.1)" is replaced with "tris(2-phenylpyridine)iridium", and the organic solvent is replaced with "composed of 20 parts by mass of ethyl 2-cyano-2-methylpropionate, 110 parts by mass of ethyl cyanoacetate and 300 parts by mass of ethyl isobutyrylate".

[0151] Device Example 1

[0152] This embodiment provides a green organic light-emitting diode with an upright structure, such as... Figure 5As shown, the green organic light-emitting diode 10 includes an anode 11, a cathode 12, a light-emitting layer 13, an electron functional layer 14, and a hole functional layer 15. The anode 11 and cathode 12 are disposed opposite each other; the light-emitting layer 13 is disposed between the anode 11 and cathode 12; the electron functional layer 14 is disposed between the cathode 12 and light-emitting layer 13, and includes a hole-blocking layer 141 and an electron transport layer 142 stacked sequentially, with the hole-blocking layer 141 closer to the light-emitting layer 13 than the electron transport layer 142; the hole functional layer 15 is disposed between the anode 11 and light-emitting layer 13, and includes a hole-injection layer 151 and a hole transport layer 152 stacked sequentially, with the hole-injection layer 151 closer to the anode 11 than the hole transport layer 152.

[0153] The structure of each layer in an organic light-emitting diode is as follows:

[0154] The anode 11 is made of ITO and has a thickness of 10 nm.

[0155] The hole injection layer 151 is made of PEDOT:PSS and has a thickness of 72nm.

[0156] The hole transport layer 152 is made of N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (CAS No. 123847-85-8), and the thickness of the hole transport layer 152 is 98 nm.

[0157] The material of the light-emitting layer 13 comprises a first compound having the structure shown in Formula (1.1) and 4,4'-bis(9-carbazole)biphenyl (second compound). The preparation method of the light-emitting layer 13 includes the steps of: inkjet printing 0.5 mL of the ink composition in Example 1 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer 13. The dimensions of the light-emitting layer 13 are 200 mm long × 200 mm wide × 66 nm thick.

[0158] The hole blocking layer 141 is made of NaF and has a thickness of 3.5 nm.

[0159] The electron transport layer 142 is made of 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (CAS No. 124729-98-2), and the thickness of the electron transport layer 142 is 20 nm.

[0160] The cathode 12 is made of Ag and has a thickness of 18 nm.

[0161] Device Example 2

[0162] This embodiment provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in Device Embodiment 1, the difference of the green organic light-emitting diode in this embodiment is that the material of the light-emitting layer is replaced with "a first compound having the structure shown in Formula (1.2) and 4,4'-bis(9-carbazole)biphenyl", and the preparation method of the light-emitting layer is replaced with "inkjet printing 0.5 mL of the ink composition in Embodiment 2 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0163] Device Example 3

[0164] This embodiment provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in Device Embodiment 1, the difference of the green organic light-emitting diode in this embodiment is that the material of the light-emitting layer is replaced with "an organic compound having the structure shown in Formula (1.3) and 4,4'-bis(9-carbazole)biphenyl", and the preparation method of the light-emitting layer is replaced with "inkjet printing 0.5 mL of the ink composition in Embodiment 3 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0165] Device Example 4

[0166] This embodiment provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in Device Embodiment 1, the difference of the green organic light-emitting diode in this embodiment is that the material of the light-emitting layer is replaced with "a first compound having the structure shown in Formula (1.1), a first compound having the structure shown in Formula (1.2), and 4,4'-bis(9-carbazole)biphenyl", and the preparation method of the light-emitting layer is replaced with "inkjet printing 0.5 mL of the ink composition in Embodiment 4 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0167] Device Example 5

[0168] This embodiment provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in device embodiment 1, the difference of the green organic light-emitting diode in this embodiment is that the preparation method of the light-emitting layer is replaced by "inkjetting 0.5 mL of the ink composition in embodiment 5 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0169] Device Example 6

[0170] This embodiment provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in Device Embodiment 1, the difference of the green organic light-emitting diode in this embodiment is that the preparation method of the light-emitting layer is replaced by "inkjetting 0.5 mL of the ink composition in Embodiment 6 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0171] Device Comparison Example 1

[0172] This comparative example provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in Device Example 1, the difference in this comparative example is that the material of the light-emitting layer is replaced with "tris(2-phenylpyridine)iridium and 4,4'-bis(9-carbazole)biphenyl", and the preparation method of the light-emitting layer is replaced with "inkjet printing 0.5 mL of the ink composition in Comparative Example 1 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0173] Device Comparison Example 2

[0174] This comparative example provides a green organic light-emitting diode with an upright structure. Compared with the green organic light-emitting diode in Device Example 1, the difference in this comparative example is that the material of the light-emitting layer is replaced with "tris(2-phenylpyridine)iridium and 4,4'-bis(9-carbazole)biphenyl", and the preparation method of the light-emitting layer is replaced with "inkjet printing 0.5 mL of the ink composition in Comparative Example 2 on the side of the hole transport layer away from the hole injection layer, and then placing it in a constant temperature heat treatment at 170°C to cure and form the light-emitting layer".

[0175] Experimental Example

[0176] The performance of the green organic light-emitting diodes in Device Examples 1 to 6, Device Comparative Examples 1 and 2 was tested. An IVL optical property measurement device was used to measure the performance of each green organic light-emitting diode at a current density of 10 mA / cm². 2 Voltage under the condition (U@10mA / cm) 2 The external quantum efficiency (EQE@1000nit, %) and current efficiency (CE@1000nit, cd / A) at a brightness of 1000 nit were measured. Performance testing was conducted at 25℃ and 40% humidity. The results are shown in Table 1 below.

[0177] Table 1. Summary of performance test results of green organic light-emitting diodes in Device Examples 1 to 6, Device Comparative Examples 1 and 2

[0178]

[0179]

[0180] As shown in Table 1, compared with the green organic light-emitting diodes in Device Comparative Example 1 and Device Comparative Example 2, the green organic light-emitting diodes in Device Examples 1 to 6 have better overall performance. Specifically, the U@10mA / cm of the green organic light-emitting diodes in Device Examples 1 to 6 is significantly improved. 2 Lower, higher EQE@1000nit, and higher CE@1000nit. Taking the green organic light-emitting diode in Device Example 4 and Device Comparative Example 1 as examples, the U@10mA / cm of the green organic light-emitting diode in Device Example 4... 2 Compared to the green organic light-emitting diode in Comparative Example 1, the U@10mA / cm 2 With a voltage 0.18V lower, the EQE@1000nit of the green organic light-emitting diode in Device Example 4 is 1.54 times that of the green organic light-emitting diode in Device Comparative Example 1, and the CE@1000nit of the green organic light-emitting diode in Device Example 4 is 1.42 times that of the green organic light-emitting diode in Device Comparative Example 1.

[0181] Therefore, compared to using tris(2-phenylpyridine)iridium as the guest material of the light-emitting layer, using the first compound with the structure shown in general formula (I) as the guest material of the light-emitting layer, and printing the light-emitting layer using the ink composition of the present application embodiment, can effectively improve the luminous efficiency of the green organic light-emitting diode, with a luminous efficiency increase of 50%. Furthermore, performance test data from device examples 1 and 6, and device comparative examples 1 and 2, show that the organic solvent in the ink composition used to form the light-emitting layer is selected from a combination of ethyl 2-cyano-2-methylpropionate, ethyl cyanoacetate, ethyl isobutyrylate, and allyl acetoacetate. This can further improve the photoelectric performance of the green organic light-emitting diode. The reason may be that the organic solvent in the ink composition, selected from a combination of ethyl 2-cyano-2-methylpropionate, ethyl cyanoacetate, ethyl isobutyrylate, and allyl acetoacetate, can meet the requirements of solubility, boiling point, viscosity, surface tension, and other aspects, thus improving the film quality of the light-emitting layer.

[0182] The above provides a detailed description of a luminescent material, ink composition, and display panel provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A luminescent material, characterized in that, The first compound includes the structure shown in the general formula (Ⅰ) below: In general formula (I), R1 and R2 are independently selected from straight-chain alkyl or branched alkyl with 3 to 8 carbon atoms.

2. The light emitting material of claim 1, wherein, R1 and R2 are independently selected from straight-chain alkyl or branched alkyl groups having 3 to 5 carbon atoms.

3. The luminescent material according to claim 1, characterized in that, The first compound has a structural formula of any one of the following formulas (1.1) to (1.3):

4. The light emitting material of claim 1, wherein, The luminescent material further includes a second compound selected from one or more of 4,4'-bis(9-carbazole)biphenyl, 2,6-bis[3-(9H-carbazole-9-yl)phenyl]pyridine, 3,5-bis(3-(9H-carbazole-9-yl)phenyl)pyridine, polyacetylene, and polythiophene compounds.

5. The luminescent material according to claim 4, characterized in that, In the luminescent material, the mass ratio of the second compound to the first compound is 1:(0.04 to 0.1).

6. An ink composition, characterized in that, The ink composition comprises at least one luminescent material as described in any one of claims 1 to 5, and at least one organic solvent.

7. The ink composition according to claim 6, characterized in that, The organic solvent, calculated by mass parts, comprises: 10 to 40 parts of ethyl 2-cyano-2-methylpropionate, 100 to 200 parts of ethyl cyanoacetate, 250 to 400 parts of ethyl isobutyrylate, and 30 to 70 parts of allyl acetoacetate.

8. The ink composition according to claim 6 or 7, characterized in that, The first compound accounts for 1.1% to 5.3% of the total mass of the ink composition.

9. A display panel, characterized in that, The display panel includes a green light-emitting unit; the green light-emitting unit includes a light-emitting material as described in any one of claims 1 to 5, or is prepared using an ink composition as described in any one of claims 6 to 8.

10. The display panel according to claim 9, characterized in that, The green light-emitting unit includes: Anode and cathode arranged opposite each other; A light-emitting layer is disposed between the anode and the cathode; An electronic functional layer is disposed between the cathode and the light-emitting layer; and A hole-functional layer is disposed between the anode and the light-emitting layer; The material of the light-emitting layer includes the light-emitting material as described in any one of claims 1 to 5, or the light-emitting layer is formed using the ink composition as described in any one of claims 6 to 8.

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