Composite material and preparation method thereof, light-emitting device and display device

Abstract

This application discloses a composite material, its preparation method, a light-emitting device, and a display device. The composite material has a core-shell structure, wherein the core of the composite material comprises metal oxide nanoparticles, and the shell of the composite material comprises Zn. z M x (PO4) y Where M is selected from H or one or more metallic elements, 0≤x / z≤0.5, 3y=2z+ax, a is the valence of M, x, y, z are integers or decimals, and the Zn z M x (PO4) y It is an amorphous material. In the technical solution proposed in this application, a zinc phosphate-based amorphous material shell is coated on the surface of the metal oxide, which can passivate surface defects of the metal oxide.

Description

Technical Field

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

[0002] Metal oxide nanoparticles, such as zinc oxide nanoparticles, molybdenum oxide nanoparticles, and tungsten oxide nanoparticles, have advantages such as excellent carrier transport performance, high transparency, and low cost, and are therefore widely used in semiconductor devices.

[0003] However, existing metal oxide nanoparticles have a large number of defects on their surface, resulting in poor stability under electric or thermal conditions. Summary of the Invention

[0004] In view of this, this application provides a composite material, a method for preparing the same, a light-emitting device, and a display device.

[0005] The embodiments of this application are implemented as follows:

[0006] In a first aspect, embodiments of this application provide a composite material with a core-shell structure. The core of the composite material comprises metal oxide nanoparticles, and the shell of the composite material comprises Zn. z M x (PO4) y Where M is selected from H or one or more metallic elements, 0≤x / z≤0.5, 3y=2z+ax, a is the valence of M, x, y, z are integers or decimals, and the Zn z M x (PO4) y It is an amorphous material.

[0007] Secondly, embodiments of this application provide a method for preparing a composite material, comprising the following steps:

[0008] The method provides metal oxide nanoparticles, a cation source, a phosphate, and a first solvent, wherein the cation source comprises a zinc salt or a mixture of a zinc salt and a metal salt of M; the metal oxide nanoparticles, the cation source, the phosphate, and the first solvent are mixed to obtain a composite material, wherein M is selected from one or more of H or metal elements.

[0009] Thirdly, embodiments of this application provide a light-emitting device, including a first electrode, a light-emitting layer, a first functional layer, and a second electrode stacked together. The material of the first functional layer includes the composite material described above, or a composite material prepared by the preparation method described above.

[0010] Fourthly, embodiments of this application provide a display device including the above-described light-emitting device.

[0011] In the technical solution proposed in this application, coating the surface of a metal oxide with an amorphous material shell of zinc phosphate can passivate the surface defects of the metal oxide, thereby enabling the prepared light-emitting device to have better performance. Attached Figure Description

[0012] 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.

[0013] Figure 1 This is a schematic flowchart of an embodiment of a method for preparing a composite material provided in this application;

[0014] Figure 2 This is a schematic diagram of the structure of an embodiment of a light-emitting device provided in this application;

[0015] Figure 3 These are XRD comparison images of the materials prepared in Material Example 1, Material Comparative Example 1, and Material Comparative Example 2 in Experimental Example (I);

[0016] Reference numerals: Light-emitting device 100; First electrode 1; Second electrode 2; First functional layer 3; Light-emitting layer 4; Second functional layer 5. 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] In a first aspect, embodiments of this application provide a composite material with a core-shell structure. The core of the composite material comprises metal oxide nanoparticles, and the shell of the composite material comprises Zn. z M x (PO4) yWhere M is selected from H or one or more metallic elements, 0≤x / z≤0.5, 3y=2z+ax, a is the valence of M, x, y, z are integers or decimals, and the Zn z M x (PO4) y It is an amorphous material.

[0021] Amorphous materials are materials that lack long-range ordered structures, and their atoms or molecules are arranged in a non-regular, periodic manner. Unlike crystalline materials, which possess long-range order and can form a definite crystal lattice structure, amorphous materials have more random atomic or molecular arrangements, lack a definite crystal lattice structure, and exhibit disordered, non-periodic characteristics.

[0022] In the technical solution proposed in this application, coating the surface of a metal oxide with an amorphous material shell of zinc phosphate can passivate surface defects of the metal oxide and prevent the metal oxide from undergoing redox reactions with the external environment, thus exhibiting better thermal and electrical stability. Furthermore, due to the isotropic nature of amorphous materials, distortion or dislocations will not occur, preventing the increase of defects during multilayer growth.

[0023] When x is 0, the shell material can be the amorphous material Zn. z (PO4) y When x > 0 and M is H, the shell material can be the amorphous material Zn. z H x (PO4) y When x > 0 and M is a metallic element, the shell material can be the amorphous material Zn. z M x (PO4) y The metallic element may be one or more selected from Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu.

[0024] It is important to note that the disordered structure of amorphous materials means that the elemental ratios may vary within a certain range. In some embodiments, the ratio of x to z can be any value or range within the range of 0 to 0.5, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, or any two of these values. y can be any value that satisfies the charge balance of the elements within the chemical formula. Specifically, x, y, and z satisfy the following formula: 3y = 2z + ax, where a is the valence of M, and x, y, and z are integers or decimals. For example, when M is Mg, a is 2, and correspondingly, 3y = 2z + 2x. In some embodiments, x is 0.5, y is 1, and z is 1. The elemental ratios in amorphous materials can be determined through experimental analysis, chemical synthesis, or other methods. For example, the relative content of different elements in amorphous materials can be determined using techniques such as mass spectrometry, elemental analysis, or X-ray diffraction.

[0025] The metal oxide nanoparticles may include N-type metal oxides or P-type metal oxides. When the metal oxide nanoparticles are selected from N-type metal oxides, the corresponding composite material has electron transport properties and can be applied in the film layer between the light-emitting layer 4 and the cathode in the light-emitting device 100. When the metal oxide nanoparticles are selected from P-type metal oxides, the corresponding composite material has hole transport or injection properties and can be applied in the film layer between the light-emitting layer 4 and the anode in the light-emitting device 100.

[0026] The N-type metal oxide may include, but is not limited to, one or more of a first undoped metal oxide and a first doped metal oxide; the first undoped metal oxide includes one or more of ZnO, SnO2, and TiO2; the first doped metal oxide includes a first oxide doped with a first dopant element, wherein the first oxide includes one or more of ZnO, SnO2, and TiO2, and the first dopant element includes one or more of Al, Mg, Li, In, and Ga. In the first doped metal oxide, the molar percentage of the first dopant element can be from 0.01% to 20%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 5%, 8%, 10%, 13%, 15%, 17%, 20%, and any two of the above values. Doping allows for precise control of the charge transport properties of the N-type metal oxide.

[0027] The p-type metal oxide may include, but is not limited to, a second undoped metal oxide and a second doped metal oxide. The second undoped metal oxide includes one or more of NiO, MoO2, WO3, and CuO. The second doped metal oxide includes a second oxide doped with a second dopant element, which includes one or more of NiO, MoO2, WO3, and CuO. The second dopant element includes one or more of Li, Na, K, Rb, and Cs. In the second doped metal oxide, the molar percentage of the second dopant element is 0.01% to 20%, for example, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 5%, 8%, 10%, 13%, 15%, 17%, 20%, and any two of the above values. Doping allows for precise control of the charge transport properties of the n-type metal oxide.

[0028] The average particle size of the core is 3–20 nm; for example, it can be 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, or any two of the above values. Further, in some embodiments, the average particle size of the core can be 3–10 nm. Controlling the core size within this range helps to regulate the overall size of the composite material and improve its charge transport properties and film-forming properties.

[0029] The average particle size described in this application can be detected by using a transmission electron microscope (TEM).

[0030] The average thickness of the shell layer is 0.5–5 nm; for example, it can be 0.5 nm, 0.8 nm, 1.0 nm, 1.3 nm, 1.5 nm, 1.8 nm, 2.0 nm, 2.3 nm, 2.5 nm, 2.7 nm, 3.0 nm, 3.5 nm, 3.8 nm, 4.0 nm, 4.5 nm, 4.7 nm, 5.0 nm, or any two of the above values. Further, in some embodiments, the average thickness of the shell layer is 0.5–3 nm. Controlling the shell layer thickness within this range helps to regulate the passivation effect of the shell layer on the core and to regulate the overall size of the composite material.

[0031] The average particle size of the composite material is 3.5–25 nm; for example, it can be 3.5 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 15 nm, 17 nm, 20 nm, 23 nm, 25 nm, or any two of the above values. Further, in some embodiments, the average particle size of the composite material can be 3.5–13 nm, which helps to control the charge transport properties, film-forming properties, and stability of the composite material.

[0032] The shell layer can be one, two, three, or more layers. The number of shell layers can be arbitrary, provided that the average particle size of the composite material is within the range of 3.5-25 nm. In some embodiments, the number of shell layers in the composite material is 1 to 3, for example, one, two, or three layers.

[0033] The materials of multiple shell layers can be the same or different, and this application does not limit this. It is understood that the materials of the core and each shell layer of a core-shell composite material can be described using a " / ", and the order from left to right represents the material types of the composite material from the inside out: core material / first shell layer material / Nth shell layer material, where N is an integer greater than or equal to 1; for example, ZnO / Zn z H x (PO4) y / Zn z (PO4) y This represents a core-shell quantum dot with a two-layer structure, where the core material is ZnO and the first shell coating the core is made of Zn. z H x (PO4) y The material of the second shell covering the first shell is Zn. z (PO4) y .

[0034] In some specific embodiments, the composite material is selected from ZnO / Zn3(PO4)2, ZnO / ZnHPO4, and ZnO / ZnMg. 0.5 One or more of PO4, ZnO / Zn3Ga(PO4)3, ZnO / Zn3(PO4)2 / ZnHPO4, SnO2 / Zn3(PO4)2, and NiO / Zn3(PO4)2. It exhibits good thermal and electrical stability, and its use in the light-emitting device 100 helps to improve device performance.

[0035] Secondly, this application also proposes a method for preparing composite materials; please refer to [link to relevant documentation]. Figure 1 The preparation method includes the following steps:

[0036] S10 provides metal oxide nanoparticles, a cation source, a phosphate, and a first solvent, wherein the cation source comprises a zinc salt or a mixture of a zinc salt and an M metal salt;

[0037] S20, the metal oxide nanoparticles, the cation source, the phosphate and the first solvent are mixed and reacted to obtain a composite material, wherein M is selected from one or more of H or metal elements.

[0038] The method described in this application can prepare a composite material with a core-shell structure, wherein the core material is metal oxide nanoparticles and the shell material is amorphous material Zn. z M x (PO4) y In this composition, M is selected from one or more of H or metallic elements, 0 ≤ x / z ≤ 0.5, 3y = 2z + ax, where x, y, and z are integers or decimals, and a is the valence of M. This composite material has relatively few surface defects and exhibits good thermal and electrical stability.

[0039] The zinc salt may include, but is not limited to, one or more of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate; the phosphate may include, or is not limited to, sodium phosphate, potassium phosphate, lithium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and lithium dihydrogen phosphate; the M metal salt may include, but is not limited to, one or more of phosphates, acetates, chlorides, and nitrates of the M metal element, and the M metal element may include, but is not limited to, one or more of Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu; the first solvent may include, but is not limited to, deionized water.

[0040] In some embodiments, the molar ratio of the metal oxide nanoparticles to the phosphate is 2 to 10:1; for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, or any range between any two of the above values.

[0041] In some embodiments, the reaction temperature is 10–30°C; for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C, or any two of the above values.

[0042] In some embodiments, the reaction time is 1 to 8 hours; for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or any two of the above values.

[0043] Based on the above preparation method, the resulting composite material is composed of metal oxide nanoparticles / Zn. z M x (PO4)y In this context, x can be 0 to 0.5, and y can be 1 to 2.

[0044] When the shell material includes the amorphous material Zn z (PO4) y In this case, the cation source is a first zinc salt, and the phosphate is selected from one or more of sodium phosphate, potassium phosphate, and lithium phosphate, and the molar ratio of the first zinc salt to the phosphate is 1 to 3:1; for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and any two of the above values.

[0045] When the material of the shell includes the amorphous material Zn z H x (PO4) y In this case, the cation source is a second zinc salt, and the phosphate includes one or more of disodium hydrogen phosphate, dipotassium hydrogen phosphate, and lithium dihydrogen phosphate, and the molar ratio of the second zinc salt to the phosphate is 1 to 3:1; for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and any two of the above values.

[0046] When the material of the shell includes the amorphous material Zn z M x (PO4) y When M is selected from one or more metal elements, the cation source is a mixture of a third zinc salt and the M metal salt, and the phosphate is selected from one or more of sodium phosphate, potassium phosphate, and lithium phosphate. The ratio of the total molar amount of metal ions in the mixture to the molar amount of the phosphate is 1 to 3:1; for example, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and any two of the above values.

[0047] In some embodiments, to promote better shell formation on the core surface, the metal oxide nanoparticles may be surface activated before mixing the metal oxide nanoparticles, the cation source, the phosphate, and the first solvent. Specifically, step S20 may include:

[0048] S21, a surface activator and a second solvent are provided, and the metal oxide nanoparticles, the surface activator and the second solvent are mixed to perform surface activation treatment to obtain activated metal oxide nanoparticles;

[0049] S22, the activated metal oxide nanoparticles are mixed with the cation source, the phosphate, and the first solvent to react, forming an amorphous material Zn on the surface of the metal oxide nanoparticles. z M x (PO4)y The resulting composite material was obtained.

[0050] The surface activator may include, but is not limited to, one or more of C10-C20 organophosphonic acid compounds, including, but not limited to, one or more of 12-mercaptododecylphosphonic acid, 13-mercaptotridecylphosphonic acid, 14-mercaptotetradecylphosphonic acid, 16-mercaptohexadecylphosphonic acid, 18-mercaptooctadecylphosphonic acid, and 20-mercaptoeicosylphosphonic acid. By activating the surface of metal oxide nanoparticles with the above-mentioned surface activator, the bonding between the shell and the nanoparticle surface can be increased.

[0051] The second solvent may include, but is not limited to, one or more of C1-C8 alcohol solvents, N,N-dimethylformamide, and dimethyl sulfoxide; the C1-C8 alcohol solvent may include, but is not limited to, one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol.

[0052] The molar ratio of the metal oxide nanoparticles to the surfactant is 1:0.1 to 1; for example, it can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, or any two of the above values.

[0053] The surface activation treatment temperature is 10–50°C; for example, it can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or any two of the above values, which can promote the reaction.

[0054] The surface activation treatment time is 12 to 24 hours; for example, it can be 12 hours, 15 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, or any two of the above values. Controlling it within this range can ensure that the reaction proceeds fully.

[0055] Thirdly, this application also proposes a light-emitting device 100, which may be, for example, a quantum dot light-emitting diode (QLED), an organic light-emitting diode (OLED), a solar cell, a light-emitting detector, etc. Please refer to... Figure 2 The light-emitting device 100 includes a first electrode 1, a light-emitting layer 4, a first functional layer 3, and a second electrode 2 stacked together. The material of the first functional layer 3 includes the composite material described above, or a composite material prepared by the preparation method described above.

[0056] In this configuration, the first electrode 1 is selected from either the anode or the cathode, and the second electrode 2 is selected from the other of the anode and the cathode. For example, the first electrode 1 can be configured as the anode and the second electrode 2 as the cathode; alternatively, the first electrode 1 can be configured as the cathode and the second electrode 2 as the anode.

[0057] Metal oxide nanoparticles are commonly used to fabricate the charge carrier functional layer located between the light-emitting layer 4 and the electrodes. However, the surface of metal oxide nanoparticles contains numerous defects, which, under electric and thermal conditions, can easily damage the material of the film layer adjacent to the charge carrier functional layer, especially the quantum dots of the light-emitting layer 4. This damage affects the effective functioning of the film layer and is detrimental to the storage stability and lifetime of the device. Furthermore, the presence of numerous defects also causes the properties of the metal oxide nanoparticles themselves to continuously change under electric and temperature treatments, leading to instability in the device's storage performance and a decrease in measured lifetime.

[0058] Therefore, in the technical solution proposed in this application, a composite material is used to prepare the first functional layer 3. Since the composite material coats the metal oxide surface with at least one layer of amorphous material such as zinc phosphate, it can passivate surface defects of the metal oxide and prevent redox reactions between the metal oxide and the external environment, thus giving the composite material better thermal and electrical stability. In this way, not only is the performance of the charge carrier functional layer itself more stable, but it also reduces the damage of the charge carrier functional layer to the materials of adjacent film layers, helping to improve the luminous efficiency and performance stability of the device and extend its lifespan. When the charge carrier functional layer is adjacent to the anode or cathode, the composite material can also coat the electrode to a certain extent, effectively preventing redox reactions between the core material and the electrode, thereby protecting the electrode material and reducing the device voltage.

[0059] The following detailed description will use LED as an example to illustrate the light-emitting device 100. The light-emitting device 100 can be an upright device or an inverted device.

[0060] The anode and cathode are each independently selected from one or more of the following: doped metal oxide particle electrode, metal-metal oxide composite electrode, graphene electrode, carbon nanotube electrode, metal electrode, or 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. In this context, " / " indicates a stacked structure. For example, the composite electrode AZO / Ag / AZO represents a three-layer composite electrode consisting of an AZO layer, an Ag layer, and an AZO layer. The thickness of the anode can range from 10 nm to 100 nm, such as 10 nm, 20 nm, 30 nm, 50 nm, 60 nm, 80 nm, and 100 nm. The thickness of the cathode can range from 15 nm to 100 nm, such as 15 nm, 30 nm, 40 nm, 50 nm, 60 nm, 80 nm, and 100 nm.

[0061] The material of the light-emitting layer 4 includes organic light-emitting materials or quantum dot light-emitting materials.

[0062] The organic light-emitting material is a material known in the art for use in the organic light-emitting layer 4. For example, it may be selected from, but is not limited to, at least one of diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent material emitting blue light, TTPA fluorescent material emitting green light, TBRb fluorescent material emitting orange light, and DBP fluorescent material emitting red light.

[0063] The quantum dot luminescent material is a quantum dot known in the art for use in the quantum dot luminescent layer 4, such as red quantum dots, green quantum dots, and blue quantum dots. The quantum dots can be selected from, but are 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 includes 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 are respectively selected from 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 are selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, and HgSeTe. At least one of the following: HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, and SnSeT. e, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the III-V compound is selected from 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, Al At least one of PSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; wherein the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2, and AgInS2.As an example, the quantum dots with 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 represents being 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, 0 < x < 1. It can be understood that the core materials of the core-shell structure quantum dots and the materials of each shell layer 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, its core material 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.

[0064] The perovskite semiconductor material is selected from doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors; the structural general formula of the inorganic perovskite semiconductor is AMX3, where A is Cs + ion, M is a divalent metal cation, selected from at least one of Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ and X is a halogen anion, selected from at least one of Cl - , Br - , I [[ID=�8]] - and the structural general formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where 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.

[0065] The thickness of the light-emitting layer 4 can be from 10nm to 60nm, such as 10nm, 15nm, 20nm, 25nm, 30nm, 40nm, 50nm, 60nm, and any two of the above values.

[0066] For ease of description, in this case, the composite material in which the metal oxide nanoparticles include N-type metal oxides is defined as the first composite material, and the composite material in which the metal oxide nanoparticles include P-type metal oxides is defined as the second composite material.

[0067] In some embodiments, when the first electrode 1 is the anode and the second electrode 2 is the cathode, the material of the first functional layer 3 can be a first composite material. Specifically, the light-emitting device 100 includes an anode, a light-emitting layer 4, a first functional layer 3, and a cathode stacked sequentially, and the material of the first functional layer 3 includes the first composite material. In this embodiment, the thickness of the first functional layer 3 can be from 10 nm to 60 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, etc.

[0068] In other embodiments, when the first electrode 1 is a cathode and the second electrode 2 is an anode, the material of the first functional layer 3 can be a second composite material. Specifically, the light-emitting device 100 includes a cathode, a light-emitting layer 4, a first functional layer 3, and an anode stacked sequentially, and the material of the first functional layer 3 includes the second composite material. In this embodiment, the thickness of the first functional layer 3 can be from 10 nm to 60 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, etc.

[0069] Furthermore, in some embodiments, the light-emitting device 100 may further include a second functional layer 5. The second functional layer 5 is disposed between the first electrode 1 and the light-emitting layer 4, that is, the light-emitting device 100 includes a first electrode 1, a second functional layer 5, a light-emitting layer 4, a first functional layer 3, and a second electrode 2 stacked sequentially. When the first electrode 1 is an anode and the second electrode 2 is a cathode, the material of the first functional layer 3 includes a first composite material, and the material of the second functional layer 5 includes a second composite material; when the first electrode 1 is a cathode and the second electrode 2 is an anode, the material of the first functional layer 3 includes a second composite material, and the material of the second functional layer 5 includes a first composite material.

[0070] It is understood that, in addition to the functional layers mentioned above, the light-emitting device 100 may also have some conventional functional layers that help improve the performance of the light-emitting device 100, such as electron blocking layer, hole blocking layer and / or interface modification layer.

[0071] It is understood that the materials and thicknesses of each layer of the light-emitting device 100 can be set and adjusted according to the light-emitting requirements of the light-emitting device 100.

[0072] Based on the above-described embodiment of the light-emitting device 100, this application also proposes a method for fabricating the light-emitting device 100. The method includes: sequentially fabricating multiple film layers according to the film layer stacking order of the light-emitting device 100 to obtain the light-emitting device 100. Specifically, the multiple film layers include, but are not limited to, an anode, a light-emitting layer 4, a first functional layer 3, and a cathode. The film layer stacking order refers to the order in which the multiple film layers are stacked. The film layer structure and stacking order of the light-emitting device 100 can be referred to the above description and will not be repeated here.

[0073] The first functional layer 3 and the second functional layer 5 can be fabricated by any common method in the art, such as physical or chemical methods. Chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods include physical deposition and solution methods. Physical deposition methods include thermal evaporation deposition, electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.; solution methods include spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating, etc.

[0074] When preparing the carrier functional layer using a solution method, the composite material can be dispersed in a suitable solvent to form a mixed solution with a composite material concentration of approximately 5–40 mg / mL. The mixed solution is then deposited to obtain the carrier functional layer. In some embodiments, when the first functional layer 3 or the second functional layer 5 uses the first composite material as the film layer material, an alcohol solvent can be used to disperse the composite material. In other embodiments, when the first functional layer 3 or the second functional layer 5 uses the second composite material as the film layer material, one or more of toluene, xylene, and chlorobenzene can be used as solvents to disperse the composite material.

[0075] It is understood that the other film layers in the light-emitting device 100 provided in this application, including the anode, cathode, light-emitting layer 4, etc., can be prepared using conventional techniques in the art, such as chemical or physical methods.

[0076] Fourthly, this application also relates to a display device, which includes the light-emitting device 100 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.

[0077] 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.

[0078] Material Example 1

[0079] This embodiment provides a composite material ZnO / Zn3(PO4)2, which is prepared by the following method:

[0080] (1) ZnO nanoparticles were prepared and the average particle size of the ZnO nanoparticles was 4 nm as detected by transmission electron microscopy (TEM).

[0081] (2) 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.48 mmol ZnSO4 and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na3PO4 was injected and reacted at room temperature (28 °C) for 1 h to obtain the composite material ZnO / Zn3(PO4)2. TEM analysis showed that the average particle size of the composite material was 5.8 nm, which means that the average thickness of the shell was about 1.8 nm.

[0082] (3) Disperse the composite material in ethanol to prepare a composite material solution with a concentration of 30 mg / mL for later use.

[0083] Material Example 2

[0084] This embodiment is basically the same as Material Embodiment 1, providing a composite material ZnO / Zn3(PO4)2. The only difference is that in step (2) of this embodiment, before adding the ZnO nanoparticles to the ZnSO4 aqueous solution, it further includes "dispersing 80 mg of ZnO in ethanol, then adding a chloroform solution containing 0.5 mmol (12-mercaptododecyl)phosphonic acid, stirring for 24 h after full dispersion, washing with acetone and redispersing in deionized water to obtain activated ZnO nanoparticles, which are then used to add to the ZnSO4 aqueous solution."

[0085] Material Example 3

[0086] This embodiment is basically the same as Material Example 2, providing a composite material ZnO / Zn3(PO4)2. The only difference is that in step (2) of this embodiment, (12-mercaptododecyl)phosphonic acid is replaced with (14-mercaptotetradecyl)phosphonic acid.

[0087] Material Example 4

[0088] This embodiment is basically the same as Material Example 2, except that the composite material provided in this embodiment is ZnO / ZnHPO4. Accordingly, in step (2) of the preparation method, 80 mg of ZnO nanoparticles are added to 22 mL of an aqueous solution containing 0.48 mmol ZnSO4 and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na2HPO4 is injected, and the mixture is reacted at room temperature (28 °C) for 1 h to obtain the composite material ZnO / ZnHPO4. TEM detection shows that the average particle size of the composite material is 6.7 nm, that is, the average thickness of the shell is approximately 2.7 nm.

[0089] Material Example 5

[0090] This embodiment is basically the same as Material Example 2, except that the composite material provided in this embodiment is ZnO / ZnMg. 0.5 PO4, accordingly, step (2) of the preparation method is changed to:

[0091] 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.38 mmol ZnSO4 and 0.1 mmol MgSO4, and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na3PO4 was added, and the mixture was reacted at room temperature (28 °C) for 1 h to obtain a ZnO / ZnMg composite material.0.5 PO4. TEM analysis showed that the average particle size of the composite material was 6.2 nm, meaning the average thickness of the shell was approximately 2.2 nm.

[0092] Material Example 6

[0093] This embodiment is basically the same as Material Example 2, except that the composite material provided in this embodiment is ZnO / Zn3Ga(PO4)3, and correspondingly, step (2) of the preparation method is changed to:

[0094] 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.38 mmol ZnSO4 and 0.05 mmol Ga2(NO3)3, and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na3PO4 was added, and the mixture was reacted at room temperature (28 °C) for 1 h to obtain a ZnO / Zn3Ga(PO4)3 composite material. TEM analysis showed that the average particle size of the composite material was 6.4 nm, indicating an average shell thickness of approximately 2.4 nm.

[0095] Material Example 7

[0096] This embodiment is basically the same as Material Example 2, except that the composite material provided in this embodiment is ZnO / Zn3(PO4)2 / ZnHPO4, and correspondingly, step (2) of the preparation method is changed to:

[0097] 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.48 mmol ZnSO4 and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na3PO4 was added, and the mixture was reacted at room temperature (28 °C) for 1 h. After washing and purification, the nanoparticles were added to another 22 mL of an aqueous solution containing 0.48 mmol ZnSO4 and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na2HPO4 was added, and the mixture was reacted at room temperature (28 °C) for 1 h, yielding a composite material of ZnO / Zn3(PO4)2 / ZnHPO4. The average particle size of the ZnO nanoparticles, the synthesized ZnO / Zn3(PO4)2, and the composite material was measured using TEM, and the average thickness of the two shells was calculated. The results showed that the average particle size of the composite material was 9 nm, the average thickness of the Zn3(PO4)2 shell was approximately 2 nm, and the average thickness of the ZnHPO4 shell was approximately 3 nm.

[0098] Material Example 8

[0099] This embodiment is basically the same as Material Example 2, except that the composite material provided in this embodiment is SnO2 / Zn3(PO4)2. Accordingly, in steps (1) and (2) of the preparation method, ZnO nanoparticles are replaced with SnO2 nanoparticles, and the average particle size of SnO2 nanoparticles is 3.2 nm. The average particle size of the composite material is 5.6 nm, that is, the average thickness of the shell is about 2.4 nm.

[0100] Material Example 9

[0101] This embodiment is basically the same as Material Example 2, except that the composite material provided in this embodiment is NiO / Zn3(PO4)2. Accordingly, in steps (1) and (2) of the preparation method, ZnO nanoparticles are replaced with NiO nanoparticles, and the average particle size of NiO nanoparticles is 6.3 nm. The average particle size of the composite material is 7.8 nm, that is, the average thickness of the shell is about 1.5 nm.

[0102] Accordingly, the composite material solution prepared in step (3) is changed to: a chlorobenzene solution of the composite material with a concentration of 30 mg / mL.

[0103] Material Comparison Example 1

[0104] This comparative example provides the ZnO nanoparticles used in step (1) of Material Example 1. Accordingly, the prepared composite material solution is changed to a ZnO ethanol solution with a ZnO nanoparticle concentration of 30 mg / mL.

[0105] Material Comparison Example 2

[0106] This comparative example is basically the same as Material Example 1, except that the composite material provided in this comparative example is ZnO / Zn3(PO4)2, and the shell layer in the composite material is a crystalline material. Accordingly, step (2) of the preparation method is changed to:

[0107] 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.48 mmol ZnSO4 and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na3PO4 was added, and the mixture was reacted at 60 °C for 12 h.

[0108] Material Comparison Example 3

[0109] This comparative example is basically the same as Material Example 1, except that the composite material provided in this comparative example is ZnO / Mg3(PO4)2, and its shell is the amorphous material Mg3(PO4)2. The average particle size of the composite material is 8.2 nm, and the average thickness of the shell is approximately 4.2 nm. Accordingly, step (2) of the preparation method is changed to:

[0110] 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.48 mmol MgSO4 and mixed thoroughly for 1 h. Then, 1.6 mL of an aqueous solution containing 0.32 mmol Na3PO4 was added, and the mixture was reacted at 60 °C for 12 h.

[0111] Material Comparison Example 4

[0112] This comparative example is basically the same as Material Example 1, except that the composite material provided in this comparative example is ZnO / amorphous ZnSO4, the average particle size of the composite material is 4.8 nm, and the average thickness of the shell is about 0.8 nm. Accordingly, step (2) of the preparation method is changed to:

[0113] 80 mg of ZnO nanoparticles were added to 22 mL of an aqueous solution containing 0.48 mmol ZnSO4 and mixed thoroughly for 1 h. The mixture was then allowed to react at room temperature (28 °C) for 1 h.

[0114] Material Comparison Example 5

[0115] This comparative example is basically the same as Material Example 1, except that the composite material provided in this comparative example is ZnO / MgO, the shell layer of the composite material is an amorphous oxide, the average particle size of the composite material is 5.2 nm, and the average thickness of the shell layer is about 1.2 nm. Accordingly, step (2) of the preparation method is changed to:

[0116] 80 mg of ZnO nanoparticles were added to 10 mL of a dimethyl sulfoxide solution containing 1 mmol of magnesium acetate and mixed thoroughly for 1 h. Then, 10 mL of an ethanol solution containing 1.1 mmol of NaOH was added, and the mixture was reacted at room temperature (28 °C) for 1 h.

[0117] Material Comparison Example 6

[0118] This comparative example provides SnO2 nanoparticles used in step (1) of Material Example 8. Accordingly, the prepared composite material solution is changed to a SnO2 ethanol solution with a SnO2 nanoparticle concentration of 30 mg / mL.

[0119] Material Comparison Example 7

[0120] This comparative example is basically the same as Material Example 8, except that the composite material provided in this comparative example is SnO2 / Zn3(PO4)2, and the shell of the composite material is a crystalline material. Accordingly, step (2) of the preparation method is adjusted to refer to step (2) of Material Comparative Example 4.

[0121] Material Comparison Example 8

[0122] This comparative example provides the NiO nanoparticles used in step (1) of Material Example 9. Accordingly, the prepared composite material solution is changed to a chlorobenzene solution of NiO with a NiO nanoparticle concentration of 30 mg / mL.

[0123] Material Comparison Example 9

[0124] This comparative example is basically the same as Material Example 9, except that the composite material provided in this comparative example is NiO / Zn3(PO4)2, and the shell of the composite material is a crystalline material. Accordingly, step (2) of the preparation method is adjusted to refer to step (2) of Material Comparative Example 4.

[0125] Device Example 1

[0126] This embodiment provides a QLED device: ITO / / PEDOT:PSS / / TFB / / QD / / first functional layer ETL / / Ag, where the first functional layer ETL uses the composite material ZnO / Zn3(PO4)2 provided in Example 1, and y is 1 to 2.

[0127] The preparation method is as follows:

[0128] Step S1: Spin-coat PEDOT:PSS onto an ITO substrate, then heat at 150°C for 30 minutes to obtain a PEDOT:PSS film with a thickness of 40 nm.

[0129] Step S2: Spin-coat a chlorobenzene solution of TFB (TFB concentration of 8 mg / mL) onto the PEDOT:PSS film, and then heat at 150°C for 30 minutes to obtain a TFB layer with a thickness of 40 nm.

[0130] Step S3: Spin-coat a hexane solution of green quantum dots CdZnSe / CdZnS / ZnS (quantum dot concentration of 20 mg / mL) onto the TFB layer, and then heat at 80 °C for 10 minutes to obtain a light-emitting layer with a thickness of 20 nm.

[0131] Step S4: Spin-coat the composite material solution prepared in Example 1 onto the light-emitting layer, and then heat at 80°C for 10 minutes to obtain a first functional layer with a thickness of 40 nm;

[0132] Step S5: Through thermal evaporation, the vacuum level is not higher than 3×10⁻⁶. -4 A 70 nm thick Ag layer is deposited on the electron transport layer at a speed of 1 angstrom / second, followed by epoxy resin encapsulation to obtain a QLED device.

[0133] Device Examples 2 to 8

[0134] Device embodiment n is basically the same as device embodiment 1, except that in the device structure provided by device embodiment n, the first functional layer ETL is made of the composite material provided by material embodiment n. Correspondingly, the spin-coating solution in step S4 of device embodiment n is replaced with the composite material solution prepared by material embodiment n, where n is any integer from 2 to 8.

[0135] Device Example 9

[0136] Device Example 9 is essentially the same as Device Example 1, except that this example provides a QLED device: ITO / / PEDOT:PSS / / first functional layer HTL / / QD / / ZnO / / Ag, where HTL is the composite material NiO / Zn3(PO4)2 provided in Material Example 9. In Device Example 9:

[0137] In step S2, the chlorobenzene solution of TFB is replaced with the composite material solution prepared in Material Example 9;

[0138] In step S4, the spin-coating solution was replaced with a ZnO ethanol solution with a concentration of 30 mg / mL, which was prepared from ZnO nanoparticles in material comparison example 1.

[0139] Device Example 10

[0140] Device Example 10 is basically the same as Device Example 1, except that this example provides a QLED device: ITO / / PEDOT:PSS / / second functional layer / / QD / / first functional layer / / Ag, where the second functional layer is made of the NiO / Zn(PO4) composite material provided in Material Example 9. y The first functional layer uses the composite material ZnO / Zn(PO4) provided in Material Example 1. y In Device Example 10:

[0141] In step S2, the chlorobenzene solution of TFB is replaced with the composite material solution prepared in Material Example 9.

[0142] Device Comparison Examples 1 to 7

[0143] The device comparison example M is basically the same as device example 1, except that in the device structure ITO / / PEDOT:PSS / / TFB / / QD / / ETL / / Ag provided in device comparison example M, ETL refers to the nanoparticles or composite materials provided in material comparison example M. Accordingly, the spin-coating solution in step S4 is replaced with the nanoparticle ethanol solution or composite material solution prepared in material comparison example M. M is selected from any integer from 1 to 7.

[0144] Device Comparison Examples 8 to 9

[0145] Device Comparative Examples 8 or 9 are essentially the same as Device Example 9, except that the device structure provided in this comparative example is ITO / / PEDOT:PSS / / HTL / / QD / / ZnO / / Ag, where HTL is the NiO nanoparticles or NiO / Zn3(PO4)4 composite material provided in Material Comparative Examples 8 and 9. Accordingly, in step S2 of the preparation method, the composite material solution obtained in Material Example 9 is replaced with the NiO chlorobenzene solution obtained in Material Comparative Example 8 or the composite material solution prepared in Material Comparative Example 9.

[0146] Experimental Example

[0147] (a) The products obtained from Material Example 1, Material Comparative Example 1, and Material Comparative Example 2 were analyzed using X-ray diffraction (XRD). The results are as follows: Figure 3 As shown.

[0148] like Figure 3 As shown, in Comparative Example 1, no other crystalline diffraction peaks appeared besides the zinc oxide peak, nor were there any amorphous material bulges. Compared to Comparative Example 1, in Example 1, in addition to the zinc oxide diffraction peak, amorphous material bulges appeared near 20° to 25°, indicating that the amorphous zinc phosphate coating was successful. In other words, Example 1 successfully coated an amorphous material layer around the ZnO core. In Comparative Example 2, characteristic diffraction peaks of zinc phosphate were observed near 19° to 20°, indicating the presence of zinc phosphate crystals. In other words, the method in Comparative Example 2 coated a zinc phosphate crystalline material layer around the ZnO core.

[0149] (II) Material Stability Testing

[0150] Materials prepared using the material examples and comparative examples were stored at 80°C and 80% RH. The fluorescence quantum yield (PLQY) and PL intensity were then measured after 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:

[0151] PLQY Detection: A 40 nm thick layer of green quantum dot material was spin-coated onto white glass, followed by heating at 80°C for 10 minutes to obtain a luminescent film. The products prepared in the material examples and comparative examples were then spin-coated onto the luminescent film, followed by heating at 80°C for 10 minutes to obtain a 40 nm thick test film. The film was then encapsulated with epoxy resin, and PLQY was detected using an Edinburgh spectrometer to investigate the effect of the materials prepared in the examples and comparative examples on the quantum yield of the luminescent film. PLQY change rate = (PLQY@0d - PLQY@14d) × 100 / PLQY@0d.

[0152] PL detection: Take a sample solution (composite material solution or nanoparticle solution), and observe the sample solution using a PL photoluminescence testing system to obtain its fluorescence emission spectrum and obtain the emission peak PL, in order to examine the changes in surface defects of the material. PL change rate = (PL@14d - PL@0d) × 100 / PL@0d.

[0153] Table 1

[0154]

[0155] As can be seen from the table above:

[0156] Regarding PL intensity @0d, Material Examples 1 to 7 are significantly lower than Material Comparative Examples 1 to 5, Material Example 8 is lower than Material Comparative Examples 6 and 7, and Material Example 9 is lower than Material Comparative Examples 8 and 9. Furthermore, regarding PLQY @0d, the Material Examples exhibit higher PLQY compared to their corresponding Material Comparative Examples. This indicates that coating the surface of metal oxide nanoparticles with at least one amorphous material layer can effectively reduce surface defects in the nanoparticles, thus passivating them and preventing metal oxides from damaging the quantum dots of the luminescent film. Moreover, the improvement in effect of Material Example 1 compared to Material Comparative Example 1 is significantly better than the improvement in effect of Material Comparative Examples 3 to 5 compared to Material Comparative Example 1. This suggests that zinc phosphate-based amorphous materials are more effective at passivating surface defects in nanoparticles. This may be because zinc phosphate-based amorphous materials have a larger binding energy, allowing them to play a more significant passivation role when used as a shell.

[0157] Meanwhile, the material examples have lower PL and PLQY change rates compared to their corresponding material comparison examples, indicating that the composite material proposed in this application causes less damage to the luminescent film and has stable performance, further corroborating the above conclusions. This shows that the shell in the composite material has the function of passivating core surface defects, reducing the amount of defects, and improving the stability of the material.

[0158] Moreover, compared to material comparison example 2, material example 1 has better performance test data. Similarly, compared to material comparison examples 7 and 9, material examples 8 and 9 also show better performance test data, indicating that the setting of amorphous material shell is more conducive to improving the stability of nanoparticles and reducing the damage of nanoparticles in adjacent film layers to adjacent film materials.

[0159] Furthermore, compared to Material Example 1, Material Examples 2 and 3 exhibit lower PL strength, PL change rate, and PLQY change rate, as well as higher PLQY. This indicates that activating the core surface before preparing the shell helps increase the bonding of the shell to the core surface, thereby reducing surface defects in the composite material and improving its stability.

[0160] (III) Device performance stability testing

[0161] Devices fabricated using the device examples and device comparison examples were tested for their CE stability and lifetime, and the results are recorded in Table 2. The testing methods are as follows:

[0162] (1) CE stability: The CE of the device is measured and recorded as CE@0d; the device is placed in an environment of 80℃ and 80%RH for 14 days, and then its CE is measured again and recorded as CE@14d. The CE stability is calculated according to the formula CE stability (%) = (CE@0d-CE@14d)×100 / CE@0d.

[0163] The CE test method is as follows: using the Fostar FPD optical property measurement equipment, an efficiency test system is built by controlling the QEPRO spectrometer, Keithley 2400, and Keithley 6485 through LabVIEW to measure parameters such as voltage, current, brightness, and emission spectrum, and the current efficiency CE is calculated.

[0164] (2) The test method for lifespan T95@1000nit is as follows:

[0165] The time required for a device's brightness to decrease to a certain percentage of its maximum brightness under constant current or voltage drive, defined as T95, is the time it takes for the brightness to drop to 95% of its maximum brightness. This lifetime is the measured lifetime. To shorten the testing cycle, device lifetime testing is usually performed at high brightness by accelerating device aging, and the lifetime at high brightness is obtained by fitting an extended exponential decay brightness decay formula. For example, the lifetime at 1000 nits is measured as T95@1000nits. The specific calculation formula is as follows:

[0166]

[0167] Among them, 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 L The value is 1000 nits, and A is the acceleration factor. 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.

[0168] Table 2

[0169]

[0170]

[0171] As can be seen from the table above, compared with devices 1 to 5, devices 1 to 7 exhibit higher current efficiency and lifetime, as well as lower CE change rate; compared with devices 6 and 7, device 8 exhibits higher current efficiency and lifetime, as well as lower CE change rate; compared with devices 8 and 9, device 9 exhibits higher current efficiency and lifetime, as well as lower CE change rate. This indicates that using composite materials to prepare the charge carrier functional layer of the light-emitting device helps to improve the current efficiency and lifetime of the device and enhance the storage stability of the device. This may be because the composite material itself is stable and has few surface defects, which helps to reduce its damage to adjacent film layers, such as the light-emitting layer material, and it is not easy to react with the electrode material, thereby effectively improving the light-emitting performance and lifetime of the device.

[0172] 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, The composite material has a core-shell structure, wherein the core of the composite material comprises metal oxide nanoparticles, and the shell of the composite material comprises Zn. z M x (PO4) y Where M is selected from H or one or more metallic elements, 0≤x / z≤0.5, 3y=2z+ax, a is the valence of M, x, y, z are integers or decimals, and the Zn z M x (PO4) y It is an amorphous material.

2. The composite material according to claim 1, characterized in that, The metallic element includes one or more of Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu.

3. The composite material according to claim 1, characterized in that, The metal oxide nanoparticles comprise N-type metal oxides, which include one or more of a first undoped metal oxide and a first doped metal oxide; the first undoped metal oxide includes one or more of ZnO, SnO2, and TiO2; the first doped metal oxide comprises a first oxide doped with a first dopant element, which includes one or more of ZnO, SnO2, and TiO2, and the first dopant element includes one or more of Al, Mg, Li, In, and Ga, wherein the molar percentage of the first dopant element in the first doped metal oxide is 0.01–20%; or, The metal oxide nanoparticles include p-type metal oxides, which include a second undoped metal oxide and a second doped metal oxide. The second undoped metal oxide includes one or more of NiO, MoO2, WO3, and CuO. The second doped metal oxide includes a second oxide doped with a second dopant element. The second oxide includes one or more of NiO, MoO2, WO3, and CuO. The second dopant element includes one or more of Li, Na, K, Rb, and Cs. The molar percentage of the second dopant element in the second doped metal oxide is 0.01–20%.

4. The composite material according to claim 1, characterized in that, The average particle size of the nuclei is 3–20 nm; optionally, the average particle size of the nuclei is 3–10 nm; and / or, The average thickness of the shell layer is 0.5–5 nm; optionally, the average thickness of the shell layer is 0.5–3 nm; and / or, The average particle size of the composite material is 3.5–25 nm; optionally, the average particle size of the composite material is 3.5–13 nm; and / or, In the composite material, the number of shell layers is 1 to 3; and / or, The composite material is selected from ZnO / Zn3(PO4)2, ZnO / ZnHPO4, and ZnO / ZnMg. 0.5 One or more of PO4, ZnO / Zn3Ga(PO4)3, ZnO / Zn3(PO4)2 / ZnHPO4, SnO2 / Zn3(PO4)2, and NiO / Zn3(PO4)2.

5. A method for preparing a composite material, characterized in that, Includes the following steps: The invention provides metal oxide nanoparticles, a cation source, a phosphate, and a first solvent, wherein the cation source comprises a zinc salt or a mixture of a zinc salt and a metal salt of M. The metal oxide nanoparticles, the cation source, the phosphate, and the first solvent are mixed and reacted to obtain a composite material, wherein M is selected from one or more of H or metal elements.

6. The preparation method according to claim 5, characterized in that, The zinc salt includes one or more of zinc sulfate, zinc acetate, zinc chloride, and zinc nitrate; and / or, The phosphate includes one or more of sodium phosphate, potassium phosphate, lithium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and lithium dihydrogen phosphate; and / or, The M metal salt includes one or more of the following: phosphate, acetate, chloride, and nitrate of the M metal element; the M metal element includes one or more of the following: Al, Mg, Li, In, Ga, Ti, Mn, Sn, Ag, and Cu; and / or, The first solvent includes deionized water; and / or, The molar ratio of the metal oxide nanoparticles to the phosphate is 2–10:1; and / or, The reaction temperature is 10–30°C; and / or, The reaction time is 1 to 8 hours.

7. The preparation method according to claim 5, characterized in that, When the cation source is a first zinc salt, and the phosphate is selected from one or more of sodium phosphate, potassium phosphate, and lithium phosphate, the molar ratio of the first zinc salt to the phosphate is 1 to 3:1; and / or, When the cation source is a second zinc salt, and the phosphate includes one or more of disodium hydrogen phosphate, dipotassium hydrogen phosphate, and lithium dihydrogen phosphate, the molar ratio of the second zinc salt to the phosphate is 1 to 3:1; and / or, The cation source is a mixture of a third zinc salt and an M metal salt. When the phosphate is selected from one or more of sodium phosphate, potassium phosphate, and lithium phosphate, and M is selected from one or more metal elements, the ratio of the total molar amount of metal ions in the mixture to the molar amount of the phosphate is 1 to 3:

1.

8. The preparation method according to claim 5, characterized in that, The step of mixing the metal oxide nanoparticles, the cation source, the phosphate, and the first solvent includes: A surface activator and a second solvent are provided. The metal oxide nanoparticles, the surface activator and the second solvent are mixed and surface activated to obtain activated metal oxide nanoparticles. The activated metal oxide nanoparticles are mixed with the cation source, the phosphate, and the first solvent; Optionally, the surfactant comprises one or more of C10-C20 organophosphonic acid compounds, wherein the C10-C20 organophosphonic acid compounds include one or more of 12-mercaptododecylphosphonic acid, 13-mercaptotridecylphosphonic acid, 14-mercaptotetradecylphosphonic acid, 16-mercaptohexadecylphosphonic acid, 18-mercaptooctadecylphosphonic acid, and 20-mercaptoeicosylphosphonic acid; and / or, The second solvent includes one or more of C1-C8 alcohol solvents, N,N-dimethylformamide, and dimethyl sulfoxide; and / or, The molar ratio of the metal oxide nanoparticles to the surfactant is 1:0.1 to 1; and / or, The surface activation treatment temperature is 10–50°C; and / or, The surface activation treatment time is 12 to 24 hours.

9. A light-emitting device, characterized in that, It includes a first electrode, a light-emitting layer, a first functional layer and a second electrode stacked together, wherein the material of the first functional layer 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 8.

10. The light-emitting device according to claim 9, characterized in that, The first electrode is the anode, the second electrode is the cathode, the material of the first functional layer includes the composite material, and the metal oxide nanoparticles in the composite material include N-type metal oxides; or... The first electrode is a cathode, the second electrode is an anode, the material of the first functional layer includes the composite material, and the metal oxide nanoparticles in the composite material include P-type metal oxides.

11. The light-emitting device according to claim 10, characterized in that, The light-emitting device further includes a second functional layer disposed between the first electrode and the light-emitting layer; When the first electrode is the anode and the second electrode is the cathode, the material of the second functional layer includes the composite material, and the metal oxide nanoparticles in the composite material include p-type metal oxides; or... The first electrode is a cathode, the second electrode is an anode, the material of the second functional layer includes the composite material, and the metal oxide nanoparticles in the composite material include N-type metal oxides.

12. The light-emitting device according to claim 9, characterized in that, The first electrode and the second electrode 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 material of the light-emitting layer includes organic light-emitting materials or quantum dot light-emitting materials. The organic light-emitting materials include 4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridinium(III), 4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridinium, diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescent materials, TTA materials, and thermally activated delayed fluorescent materials. The quantum dot luminescent material comprises one or more of the following: a polymer containing BN covalent bonds, a hybrid localized charge transfer excited-state material, and an excitocomplex luminescent material. The quantum dot luminescent material includes at least one of a single-structure quantum dot, a core-shell quantum dot, and a perovskite semiconductor material. 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 compounds from groups II-VI, IV-VI, III-V, and I-III-VI. At least one of the group II-VI compounds; the 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, CdZnSeT e, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; the IV-VI compound includes at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe and SnPbSTe;The III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, and AlN P, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInN At least one of P, 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.

13. A display device, characterized in that, Includes the light-emitting device as described in any one of claims 9 to 12.

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