Composite material, method for producing the same, thin film, optoelectronic device, and display device

Abstract

This application discloses a composite material and its preparation method, a thin film, an optoelectronic device, and a display device. The composite material includes metal oxide nanoparticles and organic ligands attached to the metal oxide nanoparticles, wherein the organic ligands contain electron-withdrawing groups. In the composite material proposed in this application, oxygen vacancies are passivated, thereby giving the material fewer defects, better storage stability, and adjusting the electron transport properties of the material, making it suitable for more application scenarios.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a composite material and its preparation method, thin film, optoelectronic device and display device. Background Technology

[0002] Metal oxide nanoparticles, such as zinc oxide nanoparticles and tin oxide nanoparticles, are widely used in semiconductor devices due to their suitable energy levels, excellent carrier injection or transport, long lifespan, high transparency, and low cost. Summary of the Invention

[0003] In view of this, this application provides a composite material and its preparation method, a thin film, an optoelectronic device, and a display device.

[0004] The embodiments of this application are implemented as follows:

[0005] In a first aspect, embodiments of this application provide a composite material comprising metal oxide nanoparticles and an organic ligand attached to the metal oxide nanoparticles, wherein the organic ligand contains an electron-withdrawing group.

[0006] Secondly, embodiments of this application provide a method for preparing a composite material, comprising the following steps:

[0007] It provides dispersions containing metal oxide nanoparticles and organic compounds containing electron-withdrawing groups;

[0008] The organic compound and the dispersion are mixed to obtain a composite material.

[0009] Thirdly, embodiments of this application provide a thin film, the material of which includes the composite material described above, or the composite material prepared by the preparation method described above.

[0010] Fourthly, embodiments of this application provide an optoelectronic device, including a stacked anode, a light-emitting layer, an electron transport layer, and a cathode, wherein the electron transport layer includes the thin film described above.

[0011] Fifthly, embodiments of this application provide a display device including the optoelectronic devices described above.

[0012] In the composite material proposed in this application, oxygen vacancies are passivated, resulting in fewer defects and better storage stability. This allows the electronic transport properties of the material to be adjusted, making it suitable for a wider range of applications. Attached Figure Description

[0013] 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.

[0014] Figure 1 This is a schematic diagram of the structure of an optoelectronic device provided in an embodiment of this application;

[0015] Figure 2 This is a schematic diagram of the structure of an optoelectronic device provided in another embodiment of this application;

[0016] Reference numerals: Optoelectronic device 100; Anode 10; Cathode 20; Light-emitting layer 30; Hole transport layer 40; Hole injection layer 50; Electron transport layer 60; First film layer 61; Second film layer 62. Detailed Implementation

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in the description of this application, the term "including" means "including but not limited to". 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 only for convenience and conciseness and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within that range. For example, it should be assumed that the description of a range from 1 to 6 specifically discloses subranges 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0018] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0019] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0020] Terminology Explanation

[0021] In this application, "aryl" refers to an aromatic hydrocarbon group derived from an aromatic ring by removing one hydrogen atom. It can be a monocyclic aryl, fused-ring aryl, or polycyclic aryl, etc. For polycyclic rings, at least one ring is an aromatic ring system. For example, a C6-C18 aryl refers to an aryl containing 6 to 18 carbon atoms, preferably an aryl having 6 to 14 carbon atoms, particularly preferably an aryl having 6 to 10 carbon atoms, and optionally further substituted. Suitable examples include, but are not limited to: phenyl, biphenyl, terphenyl, naphthyl, anthracene, phenanthrene, fluoranyl, triphenylene, pyrene, perylene, tetraphenyl, fluorenyl, dinaphthylphenyl, acenaphthyl, and their derivatives. It is understandable that multiple aryl groups can also be interrupted by short non-aromatic units (e.g., <10% non-H atoms, such as C, N or O atoms), specifically acenaphthene, fluorene, or 9,9-diarylfluorene, triarylamine, and diaryl ether systems should also be included in the definition of aryl.

[0022] In this application, "heteroaryl" refers to an aryl group in which at least one carbon atom on the ring is replaced by a non-carbon atom (heteroatom), which can be an N atom, O atom, S atom, etc. For example, a C5-C18 heterocyclic group refers to a heteroaryl group containing 5 to 18 carbon atoms, preferably a heteroaryl group having 5 to 14 carbon atoms, more preferably a heteroaryl group having 5 to 10 carbon atoms, and the heterocyclic group may optionally be further substituted. Suitable examples include, but are not limited to: thiophene, furanyl, pyrrole, imidazolyl, diazolyl, triazolyl, pyridyl, bipyridyl, pyrimidinyl, triazine, acridine, pyridazinyl, quinolinyl, isoquinolinyl, quinazole Linyl, quinoxalinyl, phthalazinyl, pyridinylpyrimidinyl, pyridinylpyrazinyl, benzothiopheneyl, benzofuranyl, indolyl, pyrroloimidazolyl, pyrrolopyrrolyl, thienopyrrolyl, thienopyrrolyl, furanolyl, furanolyl, thienofuranyl, benzoisoxazolyl, benzoisothiazolyl, benzoimidazolyl, o-diazonyl, phenanthrynyl, primidyl, quinazolinoneyl, dibenzothiopheneyl, dibenzofuranyl, carbazoleyl and their derivatives.

[0023] In this application, "alkyl" can mean straight-chain alkyl and / or branched alkyl. Cycloalkyl refers to a cyclic alkyl group. Phrases containing this term, such as "C1 to C20 alkyl", refer to alkyl groups containing 1 to 20 carbon atoms, and each time it appears, it can independently be C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl, C10 alkyl, C11 alkyl, C12 alkyl, C13 alkyl, C14 alkyl, C15 alkyl, C16 alkyl, C17 alkyl, C18 alkyl, C19 alkyl, C20 alkyl. Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, cyclohexyl, 4-methylcyclohexyl, 4-tert-butylcyclohexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, tert-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, cyclooctyl, n-nonyl, n-decyl, adamantyl, 2-ethyldecyl, 2-butyl 2-Hexyldecyl, 2-Octylide, n-Undecyl, n-Dodecyl, 2-Ethyldodecyl, 2-Butyldodecyl, 2-Hexyldodecyl, 2-Octylide, n-Tridecyl, n-Tetradecyl, n-Pentadedecyl, n-Hexadecyl, 2-Ethylhexadecyl, 2-Butylhexadecyl, 2-Hexylhexadecyl, 2-Octylide, n-Heptadedecyl, n-Octadedecyl, n-Nondecyl, n-Eicosyl, 2-Ethyleicosyl, 2-Butyleicosyl, 2-Hexyleicosyl, 2-Octylide, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, n-Iconodecyl, etc.

[0024] In this application, "alkoxy" refers to a group with the structure "-O-alkyl", that is, an alkyl group as defined above connected to other groups via an oxygen atom. Suitable examples of phrases containing this term include, but are not limited to: methoxy (-O-CH3 or -OMe), ethoxy (-O-CH2CH3 or -OEt), and tert-butoxy (-OC(CH3)3 or -OtBu). It is understood that "aryloxy" refers to a group with the structure "-O-aryl".

[0025] In this application, unless otherwise defined, hydroxyl group refers to -OH, halogen group refers to -F, -Cl, -Br or -I, carboxyl group refers to -COOH, sulfonic acid group refers to "-SO3H", cyano group refers to -C≡N, and nitro group refers to -NO2.

[0026] The terms “combinations thereof,” “any combination thereof,” and “any combination thereof” as used in this application include all suitable combinations of any two or more of the listed items.

[0027] This application provides a composite material comprising metal oxide nanoparticles and an organic ligand attached to the metal oxide nanoparticles, wherein the organic ligand contains an electron-withdrawing group.

[0028] In the composite material proposed in this application, electron-withdrawing groups are introduced on the surface of metal oxide nanoparticles, which can passivate oxygen vacancies on the surface of nanoparticles, reduce defects, and reduce the electron transport performance of the composite material, making it applicable to scenarios requiring lower electron transport capabilities. At the same time, it also makes the material have better storage stability and is less prone to sedimentation when placed in the liquid phase.

[0029] The composite material can be used in the electron transport layer 60 of the optoelectronic device 100. On the one hand, it helps to improve the stability of the device, and on the other hand, it can reduce the electron concentration formed by oxygen vacancies, thereby reducing the electron transport capability of the electron transport layer 60. At the same time, it can capture electrons, reduce the amount of electrons reaching the light-emitting layer 30, improve the problem of electron-hole transport imbalance in the device, and reduce problems such as charge accumulation, exciton quenching, and efficiency roll-off caused by excessive electron injection. In this way, it can effectively improve the service life and light-emitting performance of the optoelectronic device 100.

[0030] The electron-withdrawing group may include, but is not limited to, one or more combinations of phosphate group, tertiary amine cation, sulfonic acid group, halogen group, cyano group, and nitro group; the electron-withdrawing group has strong electron-withdrawing properties and can effectively reduce the electron concentration formed by oxygen vacancies and capture electrons.

[0031] The organic ligand can be the electron-withdrawing group or a combination of the electron-withdrawing group and the first group. The first group includes one or more combinations of halogen groups, hydroxyl groups, carboxyl groups, nitro groups, sulfonic acid groups, cyano groups, C1-C5 alkyl groups, C3-C5 cycloalkyl groups, C1-C5 alkoxy groups, aryl groups with 6 to 18 ring atoms, heteroaryl groups with 5 to 18 ring atoms, aryloxy groups with 5 to 18 ring atoms, and heteroaryloxy groups with 5 to 18 ring atoms. The organic ligand has good coordination properties, easily occupies oxygen vacancies, connects to the surface of nanoparticles, and helps improve the stability of the material, making it less prone to sedimentation when placed in the liquid phase.

[0032] The metal oxide nanoparticles may include, but are not limited to, one or more of undoped metal oxides and doped metal oxides. Specifically, the undoped metal oxides may include, but are not limited to, one or more of ZnO, SnO2, and Ta2O3; the doped metal oxides may include, but are not limited to, metal oxides doped with dopant elements, wherein the metal oxides include one or more of ZnO, SnO2, and Ta2O3, and the dopant elements may include, but are not limited to, one or more of Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu. By incorporating dopant elements, the electron transport properties of the oxides can be modulated, making them more compatible with the optoelectronic device 100.

[0033] Wherein, when the metal oxide nanoparticles include doped metal oxides, the molar percentage of the dopant element in the doped metal oxide is greater than 0 and less than or equal to 20%; for example, it can be a value greater than 0 and less than 0.001%, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 5%, 8%, 10%, 15%, 17%, 20%, or any two of the above values. By controlling it within this range, the electron transport properties of the doped metal oxide can be precisely tuned.

[0034] Furthermore, in some embodiments, the doping element can be one or more of Al, Mg, Li, and Sn. Doping the oxide with these doping elements helps to slow down electron injection. Using this doped metal oxide to prepare the composite material allows for further adjustment of the composite material's activity and electron transport properties. When this composite material is used to prepare the electron transport layer 60 of the optoelectronic device 100, it helps to improve the balance between electron and hole injection in the device.

[0035] In some embodiments, the organic ligand is connected to uncoordinated metal ions on the surface of the metal oxide nanoparticles. The surface of the metal oxide nanoparticles contains numerous oxygen vacancies and uncoordinated metal atoms not connected to oxygen atoms. The coordinating atoms of the organic ligand occupy the oxygen vacancies on the surface of the metal oxide nanoparticles and connect with the uncoordinated metal ions, thus passivating the oxygen vacancies.

[0036] The organic ligands may be derived from the following compounds: (3-(9H-carbazole-9-yl)propyl)phosphonic acid (3PACz), [4-(9H-carbazole-9-yl)butyl]phosphonic acid (4PACz), (4-(9H-carbazole-9-yl)phenyl)phosphonic acid, (2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl)phosphonic acid (Ph-2PACz), (4-(3,6-dimethyl-9H-carbazole-9-yl)phenyl)phosphonic acid. The compound comprises one or more of the following: (6-(9H-carbazol-9-yl)hexyl)phosphonic acid (Me-PhpPACz), (6-(9H-carbazol-9-yl)hexyl)phosphonic acid (6PACz), triethanolamine, tetramethylethylenediamine (TMEDA), methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, thionyl chloride, 2-chloro-1-methylpropane, 3-bromo-2,5-dimethylpentane, 2-chloro-3-bromo-4-iodobenzene, acrylonitrile, phenylpropionitrile, vinylacetonitrile, m-dinitrobenzene, nitrobenzene, and nitromethane. Using the above compounds, organic ligands can be easily introduced, introducing groups with strong electron-withdrawing properties into the composite material, effectively passivating oxygen vacancies, increasing the adsorption capacity of organic ligands in the composite material, improving the dispersibility of the composite material in alcohol solvents, enhancing the liquid-phase stability of the composite material, and reducing sedimentation during liquid-phase storage.

[0037] In some embodiments, the molar percentage of the organic ligand in the composite material is greater than 0 and less than or equal to 25%; for example, it can be any value less than 0.01% and greater than 0, 0.01%, 0.02%, 0.03%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 5%, 7%, 9%, 10%, 13%, 15%, 20%, 23%, 25%, and any range between any two of the above values. Controlling the organic ligand content within this range allows for regulation of the passivation effect and maintenance of the electron transport properties of the composite material.

[0038] In some embodiments, the average particle size of the composite material is 6–18 nm; for example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 14 nm, 15 nm, 18 nm, or any two of the above values. The composite material has suitable activity, good dispersibility, and stability.

[0039] Furthermore, this application also proposes a method for preparing a composite material, comprising the following steps:

[0040] S10 provides a dispersion containing metal oxide nanoparticles and an organic compound containing electron-withdrawing groups;

[0041] S20, the organic compound and the dispersion are mixed to obtain a composite material.

[0042] By mixing metal oxide nanoparticles with organic compounds to ensure sufficient contact, the organic compounds can be adsorbed onto the surface of the metal oxide nanoparticles, forming organic ligands attached to the surface of the metal oxide nanoparticles, thus obtaining a composite material. In this composite material, oxygen vacancies are passivated, resulting in better storage stability and adjusted material activity, making it suitable for a wider range of applications.

[0043] The preparation method of this application can produce the composite material described above. The composite material includes metal oxide nanoparticles and organic ligands attached to the metal oxide nanoparticles, wherein the organic ligands contain electron-withdrawing groups.

[0044] In this process, the ratio of the organic compound to the metal oxide nanoparticles can be controlled during the mixing of the organic compound and the dispersion to adjust the content of the organic ligands in the resulting composite material. Specifically, in some embodiments, the molar ratio of the organic compound to the metal element in the metal oxide nanoparticles is 1 to 3:9; for example, it can be 1:9, 1.5:9, 2:9, 2.5:9, 3:9, or any two of the above values.

[0045] The electron-withdrawing groups include one or more combinations of phosphate groups, tertiary amine cations, sulfonic acid groups, halogen groups, cyano groups, nitro groups, carbonyl groups, acetyl groups, alkynyl groups, and alkenyl groups; further, the organic compounds may include, but are not limited to, (3-(9H-carbazole-9-yl)propyl)phosphonic acid, [4-(9H-carbazole-9-yl)butyl]phosphonic acid, (4-(9H-carbazole-9-yl)phenyl)phosphonic acid, (2-(3,6-diphenyl-9H-carbazole-9-yl)propyl)phosphonic acid, etc. The compound comprises one or more of the following: (4-(3,6-dimethyl-9H-carbazole-9-yl)phenyl)phosphonic acid, (6-(9H-carbazole-9-yl)hexyl)phosphonic acid, triethanolamine, tetramethylethylenediamine, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, thionyl chloride, 2-chloro-1-methylpropane, 3-bromo-2,5-dimethylpentane, 2-chloro-3-bromo-4-iodobenzene, acrylonitrile, phenylpropionitrile, vinylacetonitrile, m-dinitrobenzene, nitrobenzene, and nitromethane. Using the above compounds, organic ligands can be easily introduced, introducing groups with strong electron-withdrawing properties into the composite material, effectively passivating oxygen vacancies, increasing the adsorption capacity of organic ligands in the composite material, improving the dispersibility of the composite material in alcohol solvents, enhancing the liquid-phase stability of the composite material, and reducing sedimentation during liquid-phase storage.

[0046] The metal oxide nanoparticles may include one or more of undoped metal oxides and doped metal oxides. The undoped metal oxides may include, but are not limited to, one or more of ZnO, SnO2, and Ta2O3; the doped metal oxides may include, but are not limited to, metal oxides doped with dopant elements, wherein the metal oxides include one or more of ZnO, SnO2, and Ta2O3, and the dopant elements may include, but are not limited to, one or more of Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu. By incorporating dopant elements, the electron transport properties of the oxides can be modulated, making them more compatible with the optoelectronic device 100. Furthermore, when the metal oxide nanoparticles include doped metal oxides, the molar percentage of the dopant element in the doped metal oxide is greater than 0 and less than or equal to 20%; for example, it can be a value greater than 0 and less than 0.001%, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 5%, 8%, 10%, 15%, 17%, 20%, or any two of the above values. Controlling this range allows for precise tuning of the electron transport properties of the doped metal oxide.

[0047] Furthermore, in some embodiments, the doping element can be one or more of Al, Mg, Li, and Sn. Doping the oxide with these doping elements helps to slow down electron injection. Using this doped metal oxide to prepare the composite material allows for further adjustment of the composite material's activity and electron transport properties. When this composite material is used to prepare the electron transport layer 60 of the optoelectronic device 100, it helps to improve the balance between electron and hole injection in the device.

[0048] In some embodiments, the average particle size of the metal oxide nanoparticles is 5–15 nm; for example, it can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, or any two of the above values. Based on this, the composite material can be prepared with an average particle size of 6–18 nm; for example, it can be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 14 nm, 15 nm, 18 nm, or any two of the above values.

[0049] The metal oxide nanoparticles can be purchased commercially or prepared in-house.

[0050] Specifically, it can be prepared using commonly used methods for synthesizing metal oxide nanoparticles in this field. For example, a metal salt and a first organic solvent are mixed to form a metal salt solution; a base and a second organic solvent are mixed to form an alkaline solution; the metal salt solution and the alkaline solution are mixed and reacted to obtain oxide nanoparticles. The metal salt can be one or more of zinc salts, tin salts, and titanium salts, including but not limited to; the base can be one or more of ammonia, potassium hydroxide, sodium hydroxide, ethanolamine, ethylene glycol, diethanolamine, triethanolamine, or ethylenediamine, including but not limited to; the first organic solvent can be one or more of dimethyl sulfoxide (DMSO) and DMF, including but not limited to; and the second organic solvent can be one or more of glycol methyl ether, propylene glycol methyl ether, isopropanol, ethanol, propanol, butanol, and acetone, including but not limited to.

[0051] The doped metal salts include one or more of aluminum, magnesium, lithium, indium, gallium, titanium, manganese, tin, silver, and copper salts. Specifically, each of these metal salts can be a nitrate, sulfate, acetate, or halide salt of its respective metal element. It is understood that halide salts refer to halides of metal elements. For example, magnesium salts can include one or more of magnesium nitrate, magnesium sulfate, magnesium halide, and magnesium acetate; magnesium halide salts can be one or more of magnesium fluoride, magnesium chloride, magnesium bromide, and magnesium iodide.

[0052] The dispersion may further include a first solvent, which includes one or more of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), glycol methyl ether, propylene glycol methyl ether, isopropanol, ethanol, propanol, butanol, and acetone. Using the above solvents, metal oxide nanoparticles and organic compounds can be well dispersed to form a homogeneous mixture system, thus obtaining a composite material.

[0053] In some embodiments, the mixing step can be carried out at 20–40°C, for example, at 20°C, 25°C, 30°C, 35°C, 40°C, or any two of the above values, thereby providing a suitable temperature environment to promote the combination of organic compounds and metal oxides.

[0054] In some embodiments, the mixing time is 4 to 8 hours; for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, and any two of the above values. This helps the organic compound and the metal oxide to react fully and improve the raw material conversion rate.

[0055] This application also proposes a thin film, the material of which includes the composite material described above, or the composite material prepared by the preparation method described above.

[0056] The thin film proposed in this application uses composite materials as the thin film material, which has good film-forming properties and can reduce the electron transport capability of the thin film and reduce electron enrichment, so that the thin film can be used in scenarios that require lower electron transport capability.

[0057] The film can be a single-layer film or a stacked structure formed by multiple sublayers.

[0058] In some embodiments, the thin film is a single-layer film, and the material of the single-layer film includes the composite material. In other embodiments, the thin film includes a plurality of stacked sublayers, at least one of the sublayers being a first film layer 61, the material of the at least one first film layer 61 independently including the composite material, and the material of the remaining sublayers independently including the metal oxide nanoparticles. For ease of description, the remaining sublayers based on the metal oxide nanoparticles are referred to as the second film layer 62. The first film layer 61 can reduce the electron transport capability of the thin film and trap electrons. At the same time, when multiple sublayers are stacked, an additional interfacial barrier can be introduced between the multiple sublayers to further reduce electron enrichment. When the thin film is used in the optoelectronic device 100, the amount of electrons reaching the light-emitting layer 30 can be further reduced.

[0059] The number of sublayers can be two or three; while increasing the new interfacial barrier, the fabrication difficulty of the thin film is minimized, and the charge transport performance of the thin film is ensured. Furthermore, the number of first film layers 61 can be one or two to fully utilize their functions of reducing electron concentration and capturing electrons. For example, in some embodiments, when there are three sublayers, two first film layers 61 can be provided, meaning the three sublayers include two first film layers 61 and one second film layer 62. The second film layer 62 can be disposed on one side of the two first film layers 61, i.e., the two first film layers 61 and the second film layer 62 are stacked sequentially.

[0060] This application also proposes a method for preparing a thin film, which can be used to prepare the aforementioned thin film. When the thin film is a single-layer film, the method includes: dispersing the composite material in a second solvent to obtain a composite material solution; depositing the composite material solution and annealing to obtain the thin film. When the thin film is a multilayer film, the method includes: sequentially depositing multiple sublayers according to the stacking order of multiple sublayers to obtain the thin film. Specifically, the preparation of the first film layer 61 includes: dispersing the composite material in a third solvent to obtain a composite material solution; depositing the composite material solution and annealing to obtain the first film layer 61. The preparation of the second film layer 62 includes: dispersing metal oxide nanoparticles in a fourth solvent to obtain a nanoparticle solution; depositing the nanoparticle solution and annealing to obtain the second film layer 62.

[0061] The second solvent, third solvent, and fourth solvent may each independently include one or more of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), glycol methyl ether, propylene glycol methyl ether, isopropanol, ethanol, propanol, butanol, and acetone.

[0062] The annealing temperature can be 80–120℃; 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, or any value between any two of the above. The annealing time can be 5–30 min; for example, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 12 min, 15 min, 17 min, 20 min, 22 min, 25 min, 28 min, 30 min, or any value between any two of the above. Annealing helps to improve the film formation quality of the thin film, the first film layer 61, or the second film layer 62.

[0063] This application also provides an optoelectronic device 100, please refer to [link / reference]. Figure 1 The optoelectronic device 100 further includes a stacked anode 10, a light-emitting layer 30, an electron transport layer 60, and a cathode 20, wherein the electron transport layer 60 includes the thin film described above.

[0064] The optoelectronic device 100 emits light by releasing energy through the recombination of electrons and holes. Metal oxide nanoparticles, such as zinc oxide nanoparticles and tin oxide nanoparticles, typically have high electron mobility, often much greater than the hole mobility of commonly used hole transport materials in this field. In addition, in most optoelectronic devices 100, the electron injection barrier from the cathode 20 to the light-emitting layer 30 is smaller than the hole injection barrier from the anode 10 to the light-emitting layer 30. This leads to an imbalance in electron-hole transport in the optoelectronic device 100 based on metal oxide nanoparticles, which can easily affect the device's lifespan.

[0065] In the optoelectronic device 100 proposed in this application, the electron transport layer 60 is made of the aforementioned composite material. Introducing electron-withdrawing groups into the electron transport layer 60 can, on the one hand, passivate oxygen vacancies, reduce material activity, and help improve device stability; on the other hand, it can reduce the electron concentration formed by oxygen vacancies, thereby reducing the electron transport capability of the electron transport layer 60. At the same time, it can trap electrons, reduce the amount of electrons reaching the light-emitting layer 30, improve the problem of electron-hole transport imbalance in the device, and reduce problems such as charge accumulation, exciton quenching, and efficiency roll-off caused by excessive electron injection, thereby effectively improving the service life and light-emitting performance of the optoelectronic device 100.

[0066] In the optoelectronic device 100 prepared by the method of this application embodiment, the electron transport layer 60 can be a single film layer or a composite film layer formed by stacking multiple sub-layers.

[0067] It should be noted that, regardless of whether the electron transport layer 60 is a single film layer or a composite film layer, the thickness of the electron transport layer 60 is 25–45 nm; for example, it can be 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or any two of the above values. Controlling it within this range helps to better match it with other film layers of the device, thereby improving the optoelectronic performance and lifespan of the device.

[0068] Please see Figure 2 When the electron transport layer 60 is configured as a composite film layer, that is, the thin film includes multiple sub-layers. The first film layer 61 can reduce the electron transport capability of the thin film and trap electrons. At the same time, when multiple sub-layers are stacked, an additional interface barrier can be introduced between the multiple sub-layers, further reducing the amount of electrons reaching the light-emitting layer 30, further improving the carrier balance, and reducing exciton quenching and efficiency roll-off caused by the charge on the light-emitting layer 30.

[0069] The number of sublayers can be one, two, or three; while increasing the new interfacial barrier, the fabrication difficulty of the thin film is minimized, and the charge transport performance of the thin film is ensured. Furthermore, the number of the first film layer 61 can be one or two, to fully utilize its functions of reducing electron concentration and capturing electrons. The thickness of the sublayer is 10–25 nm; for example, 10 nm, 15 nm, 20 nm, 25 nm, or any two of the above values.

[0070] When the thin film comprises multiple stacked sublayers, in the electron transport layer 60, the first film layer 61 is disposed close to the light-emitting layer 30. In this way, the first film layer 61 can not only reduce the number of electrons reaching the light-emitting layer 30, thereby reducing the electron concentration and electron transport capability of the electron transport layer 60, but also reduce electron accumulation and backpropagation at the interface between the light-emitting layer 30 and the electron transport layer 60, thus extending the device lifetime.

[0071] Furthermore, in some embodiments, the light-emitting layer 30 is located between the electron transport layer 60 and the anode 10. The thickness of the light-emitting layer 30 is 20 nm to 60 nm; for example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any two of the above values.

[0072] The material of the light-emitting layer 30 may include organic light-emitting materials or quantum dots.

[0073] The organic light-emitting material is a material known in the art for use in organic light-emitting layers, and may be selected from, but not limited to, at least one of diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent materials, TTPA fluorescent materials, TBRb fluorescent materials, and red-emitting DBP fluorescent materials.

[0074] The quantum dot is a quantum dot known in the art for use in quantum dot emitting layers, such as red quantum dots, green quantum dots, and blue quantum dots. The quantum dot can be selected from, but is not limited to, at least one of single-structure quantum dots, core-shell quantum dots, and perovskite semiconductor materials. The shell of the core-shell quantum dot comprises one or more layers. The material of the single-structure quantum dot, the core material of the core-shell quantum dot, and the shell material of the core-shell quantum dot respectively include at least one of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds. The group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, and CdSTe. At least one of the following: ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, S At least one of nSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V compound includes at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and GaAlNP. At least one of GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI group compounds include at least one of CuInS2, CuInSe2, and AgInS2; the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs. +Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of them.

[0075] As an example, the quantum dots of the core-shell structure can be selected from but not limited to at least one of CdZnSe / CdZnSe / ZnSe / CdZnS / ZnS, CdZnSe / CdZnSe / CdZnS / ZnS CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS and InP / ZnSe / ZnS. It should be noted that for the materials of the aforementioned single-structure quantum dots, or the core materials of the core-shell structure quantum dots, or the shell materials of the core-shell structure quantum dots, the provided chemical formulas only indicate the elemental composition and do not indicate the content of each element. For example, CdZnSe only indicates that it is composed of three elements, Cd, Zn and Se. If the content of each element is to be represented, it corresponds to Cd x Zn 1-x Se, where 0 < x < 1. It can be understood that the core materials and each shell layer material of the core-shell structure quantum dots are expressed by connecting with " / ", and the order from left to right is the material types of the quantum dots from the inside to the outside: core material / first shell layer material / Nth shell layer material, where N is an integer greater than or equal to 1. For example, CdSe / CdZnSeS / ZnS represents a core-shell structure quantum dot with two shell layers, the core material of which is CdSe, the material of the first shell layer coated on the core is CdZnSeS, and the material of the second shell layer coated outside the first shell layer is ZnS.

[0076] The anode 10 and the cathode 20 each independently include a doped metal oxide particle electrode, a metal-metal oxide composite electrode, a graphene electrode, a carbon nanotube electrode, a metal electrode, or an alloy electrode. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, and ITO / Ag. The electrode materials are selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba, including ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, and ZnS / Al / ZnS. The " / " indicates a stacked structure; for example, the composite electrode AZO / Ag / AZO represents a three-layered composite electrode consisting of an AZO layer, an Ag layer, and an AZO layer. The thickness of the anode 10 can be 50–120 nm, and the thickness of the cathode 20 can be 10–100 nm.

[0077] In some embodiments, the optoelectronic device 100 may further include a hole functional layer located between the light-emitting layer 30 and the anode 10. The hole functional layer includes one or both of a hole injection layer 50 and a hole transport layer 40. When the hole functional layer includes both a hole injection layer 50 and a hole transport layer 40, the hole injection layer 50 is located between the hole transport layer 40 and the anode 10. In one embodiment, the optoelectronic device 100 may include, from bottom to top, an anode 10, a hole injection layer 50, a hole transport layer 40, a light-emitting layer 30, an electron transport layer 60, and a cathode 20, stacked sequentially. In another embodiment, the optoelectronic device 100 may include, from bottom to top, a cathode 20, an electron transport layer 60, a light-emitting layer 30, a hole transport layer 40, a hole injection layer 50, and an anode 10, stacked sequentially.

[0078] The material of the hole transport layer 40 can be selected from organic materials with hole transport capabilities, including but not limited to 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), and N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NP). D), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4',4”-tris(N-3-methylphenyl-N-phenylamino) The following are included in the list of poly(p-)phenylene oxide (m-MTDATA), poly(p-)phenylene vinylidene (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylidene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylidene] (MOMO-PPV), 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS, poly(N-vinylcarbazole) (PVK), polymethacrylate, poly(9,9-octylfluorene), N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine (NPB), spiroNPB, doped graphene, undoped graphene, and one or more transition metal oxides, wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO. In some embodiments, the thickness of the hole transport layer 40 can be 20 to 60 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any value between any two of the above.

[0079] The hole injection layer 50 is made of materials known in the art that have hole injection capabilities, including but not limited to poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethylethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HATCN), copper polyester carbonate (CuPc), transition metal oxides, and metal chalcogenides; wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO; and the metal chalcogenides include one or more of MoS2, MoSe2, WS3, WSe3, and CuS. In some embodiments, the thickness of the hole injection layer 50 can be 20 to 60 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any value between any two of the above.

[0080] It is understood that the optoelectronic device 100 may also be provided with some functional layers that are conventionally used in optoelectronic devices 100 and help to improve device performance, such as electron blocking layer, hole blocking layer, interface modification layer, etc.

[0081] It is understood that the materials of each layer of the optoelectronic device 100 can be adjusted according to the optoelectronic requirements of the optoelectronic device 100.

[0082] It is understood that the optoelectronic device 100 can be an upright device or an inverted device.

[0083] Furthermore, this application also proposes a method for fabricating an optoelectronic device 100, which can be used to fabricate the aforementioned optoelectronic device 100. The fabrication method may include: providing a first electrode; sequentially fabricating multiple film layers on one side of the first electrode according to a preset film layer sequence to obtain a functional layer; and fabricating a second electrode on the side of the functional layer opposite to the first electrode to obtain the optoelectronic device 100. The first electrode is selected from either an anode 10 or a cathode 20, and the second electrode is selected from the other of an anode 10 or a cathode 20; the multiple film layers include a light-emitting layer 30 and an electron transport layer 60. It can be understood that the preset film layer sequence refers to the stacking order of the film layers of the optoelectronic device 100 to be fabricated. For example, in one embodiment, the first electrode is an anode 10, the second electrode is a cathode 20, and the preset film layer sequence is to sequentially fabricate the light-emitting layer 30 and the electron transport layer 60; in another embodiment, the first electrode is a cathode 20, the second electrode is an anode 10, and the preset film layer sequence is to sequentially fabricate the electron transport layer 60 and the light-emitting layer 30.

[0084] The electron transport layer 60 can be prepared using the same method as described above for preparing thin films. Further details will not be provided here.

[0085] In some embodiments, the functional layer of the optoelectronic device 100 to be fabricated further includes other film layers such as a hole functional layer. During actual fabrication, the corresponding target film layer can be fabricated at the location of the target film layer according to the film layer sequence. For example, the hole functional layer includes one or both of a hole transport layer 40 and a hole injection layer 50, with the hole transport layer 40 located between the light-emitting layer 30 and the anode 10, and the hole injection layer 50 located between the hole transport layer 40 and the anode 10. In a specific embodiment, the structure of the optoelectronic device 100 to be fabricated is an anode 10, a hole injection layer 50, a hole transport layer 40, a light-emitting layer 30, an electron transport layer 60, and a cathode 20 stacked sequentially from bottom to top. Therefore, the optoelectronic device 100 is fabricated sequentially according to the film layer sequence.

[0086] The methods for forming the films such as the anode 10, cathode 20, light-emitting layer 30, hole transport layer 40, and hole injection layer 50 can be chemical or physical methods. Chemical methods can include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods can include physical deposition or solution processing. Physical deposition methods include thermal evaporation deposition (CVD), electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition (PVD), atomic layer deposition, and pulsed laser deposition. Solution processing methods include spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating. Those skilled in the art can prepare the various films of the optoelectronic device 100 of this application embodiment according to the known methods for preparing optoelectronic devices 100, which will not be elaborated further here.

[0087] Furthermore, embodiments of this application also relate to a display device, which includes the optoelectronic device 100 provided in this application, or the optoelectronic device 100 prepared by the method described above. The display device can be any electronic product with display functionality, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0088] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0089] Materials and Thin Films Example 1

[0090] (1) At 25℃, 9 mmol of zinc acetate, 2 mmol of magnesium acetate dihydrate and 30 mL of DMSO were placed in a 100 mL three-necked flask and mixed. Argon gas was introduced and the mixture was stirred for 1 h to obtain a salt solution with no obvious particles and uniform dispersion.

[0091] (2) At 25℃, 10 mmol of lithium hydroxide and 30 mL of ethanol were placed in a 60 mL glass bottle, stirred for 1 h, and sonicated for 5 min to obtain a colorless and transparent alkaline solution.

[0092] (3) Use a 30mL syringe to draw 30mL of alkaline solution and inject it into the salt solution, and let it react for 18h;

[0093] (4) Add 2 mmol of organic compound (4PACz) to the solvent in step (3) and react for 5 h.

[0094] (5) Pour the mixture evenly into four 50 mL centrifuge tubes, add 30 mL of ethyl acetate, and centrifuge.

[0095] (6) Take the precipitate and add 2 mL of ethanol. Shake until the white solid is completely dissolved to obtain a tube of 8 mL of mixed solution containing the composite material. The composite material is ZnMgO nanoparticles with [4-(9H-carbazole-9-yl)butyl]phosphonic acid groups on the surface. The average particle size of the composite material is about 14 nm.

[0096] (7) Centrifuge the ethanol solution of the composite material, take the supernatant, filter it, and obtain the ethanol solution of the composite material. Store it in a freezer at -15℃ for later use.

[0097] (8) Spin-coat the ethanol solution of the composite material prepared in step (7) onto the glass substrate at a speed of 4000 rpm for 30 s, and then heat it on an 80°C heating plate for 8 min to obtain a film with a thickness of 30 nm.

[0098] Materials and Thin Films Example 2

[0099] This embodiment is basically the same as the material and film embodiment 1, except that in this embodiment, the organic compound is Ph-2PACz, and accordingly, a composite material is prepared - ZnMgO nanoparticles with (2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl)phosphonic acid groups on the surface, and the average particle size of the composite material is about 14 nm.

[0100] Materials and Thin Films Example 3

[0101] This embodiment is basically the same as the material and film embodiment 1, except that in this embodiment, the organic compound is methanesulfonic acid, and accordingly, a composite material is prepared - ZnMgO nanoparticles with methanesulfonic acid attached to the surface, and the average particle size of the composite material is about 14 nm.

[0102] Materials and Thin Films Example 4

[0103] This embodiment is basically the same as the material and film embodiment 1, except that in this embodiment, the organic compound is vinyl acetonitrile, and accordingly, a composite material is prepared - ZnMgO nanoparticles with vinyl acetonitrile attached to the surface, and the average particle size of the composite material is about 14 μm.

[0104] Materials and Thin Films Example 5

[0105] This embodiment is basically the same as that of the materials and film embodiment 1, except that the amount of organic compound added in this embodiment is 1 mmol.

[0106] Materials and Thin Films Example 6

[0107] This embodiment is basically the same as that of the materials and film embodiment 1, except that the amount of organic compound added in this embodiment is 3 mmol.

[0108] Materials and Thin Films Example 7

[0109] This embodiment is basically the same as that of the materials and film embodiment 1, except that the amount of organic compound added in this embodiment is 4 mmol.

[0110] Materials and Thin Films Example 8

[0111] This embodiment is basically the same as the material and film embodiment 1, except that the composite material in this embodiment is ZnO nanoparticles with [4-(9H-carbazole-9-yl)butyl]phosphonic acid groups connected to the surface, and correspondingly, magnesium acetate dihydrate is not added in step (1).

[0112] Comparative Example 1 of Materials and Thin Films

[0113] This comparative example is basically the same as the material and film example 1, except that the material proposed in this example is ZnMgO, and correspondingly, no organic compounds are added in the preparation steps to obtain an ethanol solution of ZnMgO and a film based on ZnMgO.

[0114] Comparative Example 2 of Materials and Thin Films

[0115] This comparative example is basically the same as the material and film example 1, except that the material proposed in this example is ZnMgO with 1,2-ethylenedithiol attached to its surface. Correspondingly, in the preparation step (4), the organic compound is replaced with 1,2-ethylenedithiol to obtain an ethanol solution of ZnMgO with 1,2-ethylenedithiol attached to its surface and a film based on ZnMgO with 1,2-ethylenedithiol attached to its surface.

[0116] Comparative Example 3 of Materials and Thin Films

[0117] This comparative example is basically the same as the material and film example 8, except that the material proposed in this example is ZnO, and correspondingly, no organic compounds are added in the preparation steps to obtain an ethanol solution of ZnO and a ZnO-based film.

[0118] Device Example 1

[0119] This embodiment provides a QLED device with a structure of ITO (80nm) / PEDOT:PSS (20nm) / TFB (20nm) / QD (40nm) / ETL1 (15nm) / ETL2 (15nm) / Al (100nm), and the fabrication method is as follows:

[0120] Step S1: The substrate coated with 80nm thick ITO was ultrasonically cleaned with acetone and ethanol for 15 minutes, then cleaned again with deionized water, dried on a heating plate at 150℃ for 10 minutes, and finally irradiated with ultraviolet light for 20 minutes to obtain the ITO anode.

[0121] Step S2: Place the cleaned ITO anode into a glove box, spin-coat the ITO surface with an aqueous solution of PEDOT:PSS (mass fraction of 2.8wt%) at 3000 rpm for 30 s, and then heat it on a 150℃ heating plate for 20 min to obtain a hole injection layer with a thickness of 20 nm.

[0122] Step S3: Spin-coat a chlorobenzene solution of TFB (concentration of 6.5 mg / mL) onto the hole injection layer at 3000 rpm for 30 s, and then heat it on a 120°C heating plate for 20 min to obtain a hole transport layer with a thickness of 20 nm.

[0123] Step S4: Spin-coat a hexane solution of ZnCdSe blue quantum dots (10 mg / mL) onto the hole transport layer at 1500 rpm for 30 s, and then heat it on a 100°C heating plate for 5 min to obtain a light-emitting layer with a thickness of 40 nm.

[0124] Step S5: Spin-coat an ethanol solution of the composite material prepared in Example 1 onto the luminescent layer at 4000 rpm for 30 s, followed by heating on an 80°C heating plate for 8 min to obtain a first sublayer (ETL1) with a thickness of 15 nm. Spin-coat an ethanol solution of ZnMgO prepared in Comparative Example 1 onto the first sublayer at 4000 rpm for 30 s, followed by heating on an 80°C heating plate for 8 min to obtain a second sublayer (ETL2) with a thickness of 15 nm.

[0125] Step S6: Through thermal evaporation, the vacuum level is not higher than 3×10. -4 Pa, Al vapor deposition, speed is A positively positioned quantum dot light-emitting diode was obtained with a time of 100s and a thickness of 100nm.

[0126] Device Examples 2 to 8

[0127] The scheme of Example n is basically the same as that of Device Example 1, except that in step S5 of Examples 2 to 8, the first sublayer is prepared using an ethanol solution of the composite material of Material and Thin Film Example n, where n is any integer from 2 to 8.

[0128] Device Example 9

[0129] The scheme of this embodiment is basically the same as that of embodiment 8, except that the material of the second sublayer in this embodiment is ZnO. Accordingly, when preparing the second sublayer, the ZnO ethanol solution in material and film comparison example 3 is used.

[0130] Device Example 10

[0131] The scheme of this embodiment is basically the same as that of embodiment 1, except that the material of the second sublayer in this embodiment is ZnMgO with [4-(9H-carbazole-9-yl)butyl]phosphonic acid groups on the surface. Correspondingly, the ethanol solution of the composite material in embodiment 1 is used to prepare the second sublayer.

[0132] Device Example 11

[0133] The scheme in this embodiment is basically the same as that in Embodiment 1, except that there is no second sublayer in this embodiment, and correspondingly, the thickness of the first sublayer is changed to 30nm. In the preparation method, the step of preparing the second sublayer is omitted.

[0134] Device Comparison Examples 1 to 3

[0135] The scheme of Comparative Example m is basically the same as that of Device Example 11, except that there is no second sub-layer in Comparative Example m, the thickness of the first sub-layer is adjusted to 30nm, and the material of the first sub-layer is the same as that of the material and film Comparative Example m. Correspondingly, in step S5 of Comparative Examples 1 to 3, the first sub-layer is prepared by using an ethanol solution of the composite material of the material and film Comparative Example m, where m is any integer from 1 to 3.

[0136] Device Comparison Example 4

[0137] This comparative example is basically the same as that of device example 1, except that this comparative example does not have a second sublayer, and the first sublayer is ZnMgO. Accordingly, in step S5, the step of preparing the second sublayer is omitted, and the first sublayer is prepared using an ethanol solution of ZnMgO from material and film comparative example 1.

[0138] Device Comparison Example 5

[0139] This comparative example is basically the same as the device example 1, except that this comparative example does not have a second sublayer, and the first sublayer is ZnMgO with 1,2-ethylenedithiol attached to its surface. Correspondingly, in step S5, the step of preparing the second sublayer is omitted, and the first sublayer is prepared using an ethanol solution of ZnMgO with 1,2-ethylenedithiol attached to its surface from the material and film comparative example 2.

[0140] Device Comparison Example 6

[0141] This comparative example is basically the same as the device example 1, except that this comparative example does not have a second sublayer, and the first sublayer is ZnO. Accordingly, in step S5, the step of preparing the second sublayer is omitted, and the first sublayer is prepared using an ethanol solution of ZnO from material and film comparative example 3.

[0142] Experimental Example

[0143] (a) The performance of the composite materials prepared by the above materials, thin film examples and comparative examples was tested in ethanol solution. The results are shown in Table 1.

[0144] The detection method was as follows: An ethanol solution of the composite material was taken and stored at 25℃ and 80% RH. The fluorescence quantum yield (PLQY) was then measured at different storage days (day 0 and day 14), and the rate of change was calculated. The results are recorded in Table 1. The detection method is as follows:

[0145] PLQY detection: Take the sample solution (ethanol solution of the composite material) and perform PLQY detection using an Edinburgh spectrometer. PL change rate = (PL@14d - PL@0d) × 100 / PL@0d.

[0146] Table 1

[0147]

[0148]

[0149] As can be seen from the table above:

[0150] Compared to Comparative Examples 1 and 2, the composite materials prepared in Examples 1 to 7 all have higher PLQY@0d and lower PLQY change rate. Compared to Comparative Example 3, the composite material prepared in Example 8 all have higher PLQY@0d and lower PLQY change rate. This indicates that in the composite material proposed in this application, by attaching an organic ligand containing an electron-withdrawing group to the surface of the metal oxide nanoparticles, oxygen vacancies can be passivated and defects reduced, making the composite material less prone to sedimentation when placed in the liquid phase and exhibiting better stability.

[0151] (II) Performance tests were conducted on the QLED devices prepared in the above embodiments and comparative examples. The results are shown in Table 2. The testing methods are as follows:

[0152] (1) External quantum dot efficiency:

[0153] The ratio of electron-hole pairs injected into a quantum dot to emitted photons, expressed as a percentage (%), is an important parameter for evaluating the quality of electroluminescent devices. It can be measured using an EQE optical testing instrument. The specific calculation formula is as follows:

[0154]

[0155] Where ηe is the optical output coupling efficiency, ηr is the ratio of recombination carriers to injected carriers, χ is the ratio of the number of excitons generating photons to the total number of excitons, and K R K is the radiation process rate. NR This represents the rate of a non-radiative process.

[0156] Test conditions: Conducted at room temperature with an air humidity of 30-60%.

[0157] (2) Lifetime: The time required for the brightness of a device to decrease to a certain percentage of its maximum brightness under constant current or voltage driving. The time for the brightness to decrease to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the testing cycle, device lifetime testing is usually performed by accelerating device aging under high brightness, referencing OLED device testing, and the lifetime under high brightness is obtained by fitting the extended exponential decay brightness decay fitting formula. For example, the lifetime at 1000 nits is measured as T95. 1000nit The specific calculation formula is as follows:

[0158]

[0159] In the formula, T95 L For longer lifespan at low brightness, T95 H For the measured lifetime under high brightness, L H To accelerate the device to its maximum brightness, L LThe value is 1000 nits, and A is the acceleration factor. For OLEDs, this value is usually 1.6 to 2. In this experiment, the lifetime of several groups of QLED devices under rated brightness was measured, and the value of A was found to be 1.7.

[0160] The life test system was used to test the life of the corresponding devices. The test conditions were: room temperature and air humidity of 30-60%.

[0161] Table 2

[0162]

[0163]

[0164] As can be seen from the table above:

[0165] Examples 1 through 11 all exhibit high EQE and T95. 1000nit This demonstrates that the optoelectronic device proposed in this application has high luminous performance and long service life;

[0166] Furthermore, Examples 1 to 4 have higher EQE and T95 than Comparative Examples 1 and 4. 1000nit Examples 8 and 9 have higher EQE and T95 than Comparative Examples 3 and 6. 1000nit This application demonstrates that using composite materials to prepare the electron transport layer helps improve carrier balance and reduce exciton quenching and efficiency roll-off caused by charged emitting layers; EQE and T95 of Examples 1, 10, 8, and 9. 1000nit The decreasing order indicates that using Mg-doped zinc oxide helps to further improve carrier balance;

[0167] Meanwhile, Example 1 has higher EQE and T95 than Comparative Examples 2 and 5. 1000nit This indicates that introducing electron-withdrawing groups into composite materials helps to reduce the electron concentration caused by oxygen vacancies, thereby reducing the electron transport capacity of the electron transport layer and regulating the carrier balance.

[0168] Furthermore, Example 1 has higher EQE and T95 than Example 11. 1000nit This indicates that designing the electron transport layer as a stacked structure can introduce a new interface barrier, further reduce the number of electrons reaching the surface of the light-emitting layer, improve carrier balance, and reduce exciton quenching and efficiency roll-off caused by the charge on the light-emitting layer.

[0169] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composite material, characterized in that, It includes metal oxide nanoparticles and organic ligands attached to the metal oxide nanoparticles, the organic ligands containing electron-withdrawing groups.

2. The composite material according to claim 1, characterized in that, The electron-withdrawing group includes one or more combinations of phosphate, tertiary amine cation, sulfonic acid, halogen, cyano, and nitro groups; and / or, The metal oxide nanoparticles include one or more of undoped metal oxides and doped metal oxides; the undoped metal oxides include one or more of ZnO, SnO2, and Ta2O3; the doped metal oxides include metal oxides doped with a dopant element, wherein the metal oxides include one or more of ZnO, SnO2, and Ta2O3, and the dopant element includes one or more of Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu; optionally, in the doped metal oxides, the molar percentage of the dopant element is greater than 0 and less than or equal to 20%; and / or, The organic ligand is the electron-withdrawing group or a combination of the electron-withdrawing group and a first group, wherein the first group includes one or more combinations of halogen groups, hydroxyl groups, carboxyl groups, nitro groups, sulfonic acid groups, cyano groups, C1-C5 alkyl groups, C3-C5 cycloalkyl groups, C1-C5 alkoxy groups, aryl groups with 6 to 18 ring atoms, heteroaryl groups with 5 to 18 ring atoms, aryloxy groups with 5 to 18 ring atoms, and heteroaryloxy groups with 5 to 18 ring atoms; and / or, The organic ligand is connected to the uncoordinated metal ions on the surface of the metal oxide nanoparticles.

3. The composite material according to claim 2, characterized in that, The organic ligand is derived from one or more of the following: (3-(9H-carbazole-9-yl)propyl)phosphonic acid, [4-(9H-carbazole-9-yl)butyl]phosphonic acid, (4-(9H-carbazole-9-yl)phenyl)phosphonic acid, (2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(3,6-dimethyl-9H-carbazole-9-yl)phenyl)phosphonic acid, (6-(9H-carbazole-9-yl)hexyl)phosphonic acid, triethanolamine, tetramethylethylenediamine, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, thionyl chloride, 2-chloro-1-methylpropane, 3-bromo-2,5-dimethylpentane, 2-chloro-3-bromo-4-iodobenzene, acrylonitrile, phenylpropionitrile, vinylacetonitrile, m-dinitrobenzene, nitrobenzene, and nitromethane.

4. The composite material according to claim 1, characterized in that, In the composite material, the molar percentage of the organic ligand is greater than 0 and less than or equal to 25%; and / or, The average particle size of the composite material is 6–18 nm.

5. A method for preparing a composite material, characterized in that, Includes the following steps: It provides dispersions containing metal oxide nanoparticles and organic compounds containing electron-withdrawing groups; The organic compound and the dispersion are mixed to obtain a composite material.

6. The preparation method according to claim 5, characterized in that, The molar ratio of the organic compound to the metal element in the metal oxide nanoparticles is 1 to (3:9); and / or, The average particle size of the metal oxide nanoparticles is 5–15 nm; and / or, The electron-withdrawing groups include one or more combinations of phosphate, tertiary amine cation, sulfonic acid, halogen, cyano, nitro, carbonyl, acetyl, alkynyl, and alkenyl groups; and / or, The metal oxide nanoparticles include one or more of undoped metal oxides and doped metal oxides; the undoped metal oxides include one or more of ZnO, SnO2, and Ta2O3; the doped metal oxides include metal oxides doped with a dopant element, wherein the metal oxides include one or more of ZnO, SnO2, and Ta2O3, and the dopant element includes one or more of Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu; optionally, in the doped metal oxides, the molar percentage of the dopant element is greater than 0 and less than or equal to 20%; and / or, The dispersion further includes a first solvent, which comprises one or more of dimethyl sulfoxide, N,N-dimethylformamide, glycol methyl ether, propylene glycol methyl ether, isopropanol, ethanol, propanol, butanol, and acetone; and / or, The mixing temperature is 20–40°C; and / or, The mixing time is 4 to 8 hours.

7. The preparation method according to claim 6, characterized in that, The organic compounds include one or more of the following: (3-(9H-carbazole-9-yl)propyl)phosphonic acid, [4-(9H-carbazole-9-yl)butyl]phosphonic acid, (4-(9H-carbazole-9-yl)phenyl)phosphonic acid, (2-(3,6-diphenyl-9H-carbazole-9-yl)ethyl)phosphonic acid, (4-(3,6-dimethyl-9H-carbazole-9-yl)phenyl)phosphonic acid, (6-(9H-carbazole-9-yl)hexyl)phosphonic acid, triethanolamine, tetramethylethylenediamine, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, thionyl chloride, 2-chloro-1-methylpropane, 3-bromo-2,5-dimethylpentane, 2-chloro-3-bromo-4-iodobenzene, acrylonitrile, phenylpropionitrile, vinylacetonitrile, m-dinitrobenzene, nitrobenzene, and nitromethane.

8. A thin film, characterized in that, The material of the film includes the composite material according to any one of claims 1 to 4, or the composite material prepared by the preparation method according to any one of claims 5 to 7.

9. The thin film according to claim 8, characterized in that, The film is a single-layer film, and the material of the single-layer film includes the composite material; or... The thin film comprises a plurality of stacked sublayers, at least one of the sublayers being a first film layer, the material of the at least one first film layer being the composite material, and the remaining sublayers being a second film layer, the material of the second film layer being the metal oxide nanoparticles.

10. The thin film according to claim 9, characterized in that, The number of sublayers is two or three; optionally, when there are three sublayers, the three sublayers include two first film layers and one second film layer, with the two first film layers and the second film layer stacked sequentially; and / or, The number of the first film layers is 1 to 2.

11. An optoelectronic device, characterized in that, It includes a stacked anode, a light-emitting layer, an electron transport layer, and a cathode, wherein the electron transport layer comprises the thin film according to any one of claims 8 to 10.

12. The optoelectronic device according to claim 11, characterized in that, The thickness of the electron transport layer is 25–45 nm; and / or, When the thin film comprises multiple stacked sublayers, in the electron transport layer, the first film layer is disposed close to the light-emitting layer; and / or, When the thin film comprises multiple stacked sublayers, the thickness of the sublayers is 10–25 nm; and / or, The material of the light-emitting layer includes organic light-emitting materials or quantum dots. The organic light-emitting materials include at least one of diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent materials, TTPA fluorescent materials, TBRb fluorescent materials, and DBP fluorescent materials. The quantum dots include at least one of single-structure quantum dots, core-shell quantum dots, and perovskite semiconductor materials. The shell of the core-shell quantum dots comprises one or more layers. The material of the single-structure quantum dots, the core material of the core-shell quantum dots, and the shell material of the core-shell quantum dots respectively include group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-II compounds. At least one of group II-VI compounds; said group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe The group IV-VI compounds include at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the group III-V compounds include at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, G At least one of aNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the group I-III-VI compounds include at least one of CuInS2, CuInSe2, and AgInS2;The perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors; the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of them; and / or, The anode and cathode each independently include a doped metal oxide particle electrode, a metal-metal oxide composite electrode, a graphene electrode, a carbon nanotube electrode, a metal electrode, or an alloy electrode. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from 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, and ZnS / Al / ZnS. The material of the metal electrode is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba; and / or, The optoelectronic device further includes a hole functional layer disposed between the light-emitting layer and the anode. The hole functional layer includes one or both of a hole transport layer and a hole injection layer. When the hole functional layer includes both the hole transport layer and the hole injection layer, the hole injection layer is located between the anode and the hole transport layer. The material of the hole transport layer includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], and N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1' -Biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly(p-)phenylenevinylene, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'- [dimethyloctyloxy]-1,4-phenylenevinylene, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS, poly(N-vinylcarbazole), polymethacrylate, poly(9,9-octylfluorene), N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine, spiron NPB, doped graphene, undoped graphene, C60, and one or more transition metal oxides, wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO; the material of the hole injection layer includes The following are selected from one or more of the following: poly(3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethane, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, polyester copper carbonate, transition metal oxides, and metal chalcogenides; wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO; and the metal chalcogenides include one or more of MoS2, MoSe2, WS3, WSe3, and CuS.

13. A display device, characterized in that, Includes the optoelectronic device as described in claim 11 or 12.

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