Nanoparticles, methods of making the same, thin films, and optoelectronic devices

Abstract

The application provides a kind of nanoparticles and its preparation method, thin film and optoelectronic device. The nanoparticles provided by the application can weaken the hole quenching or exciton quenching at the interface between adjacent film layers in the optoelectronic device, thereby improving the light-emitting efficiency and service life of the optoelectronic device, etc.

Description

Technical Field

[0001] This application relates to the field of optoelectronic devices, and in particular to a nanoparticle and its preparation method, a thin film, and an optoelectronic device. Background Technology

[0002] Electroluminescent devices include OLED (Organic Light-Emitting Diode) and QLED (Quantum Dot Light-Emitting Diodes). QLED has advantages such as high color saturation, wet fabrication capability, and high stability, which has led to increasing attention on QLED research. OLED, with its excellent self-emissive properties, high contrast, fast response, and flexible display capabilities, has wide applications in display, lighting, and smart wearable devices.

[0003] The carrier transport material in electroluminescent devices can be metal oxide nanoparticles (such as WO3 particles, ZnO particles, etc.). However, due to the large number of surface defects (such as oxygen vacancies and lattice dislocation defects) in metal oxide nanoparticles, hole quenching or exciton quenching is prone to occur at the interface between adjacent film layers in electroluminescent devices, which leads to the degradation of the luminous efficiency and lifespan of electroluminescent devices. Summary of the Invention

[0004] Based on this, embodiments of this application provide nanoparticles, a method for preparing the same, thin films, and optoelectronic devices.

[0005] In a first aspect, embodiments of this application provide a nanoparticle, including a core and a shell covering the outer surface of the core, wherein the material of the core includes a single metal oxide, the material of the shell includes a doped metal oxide, the single metal oxide includes a first metal element, and the doped metal oxide includes a second metal element and a third metal element;

[0006] Wherein, the first metal element and the third metal element are independently selected from group VIB, group IIB, group IIA, group IVB or group IVA elements, and the second metal element is selected from group IA or group IIA elements.

[0007] Secondly, embodiments of this application provide a method for preparing nanoparticles, comprising:

[0008] A core is provided, the core material comprising a single metal oxide, the single metal oxide comprising a first metal element;

[0009] A shell material is coated on the surface of the core. The shell material includes a doped metal oxide, which includes a second metal element and a third metal element, to obtain nanoparticles. The nanoparticles include a core and a shell coating the outer surface of the core. The first metal element and the third metal element are independently selected from Group VIB, Group IIB, Group IIA, Group IVB, and Group IVA elements, respectively, and the second metal element is selected from Group IA and Group IIA elements.

[0010] Thirdly, embodiments of this application provide a thin film comprising nanoparticles as described above or nanoparticles prepared by the method described above.

[0011] Fourthly, embodiments of this application provide an optoelectronic device, including a cathode and an anode disposed opposite to each other, and a functional layer disposed between the cathode and the anode, wherein the material of the functional layer includes nanoparticles as described above or nanoparticles prepared by the method described above.

[0012] The nanoparticles provided in this application embodiment, by coating the core surface with a shell layer, wherein the core material includes a single metal oxide and the shell material includes a doped metal oxide, can passivate defects on the core surface using the shell material. These nanoparticles can be used as carrier transport materials in optoelectronic devices, which can reduce hole quenching or exciton quenching at the interface between adjacent film layers in optoelectronic devices, thereby improving the luminous efficiency and lifespan of optoelectronic devices. 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.

[0014] Figure 1 This is a schematic diagram of the structure of nanoparticles provided in an embodiment of this application.

[0015] Figure 2 A flowchart illustrating the preparation method of nanoparticles provided in this application embodiment.

[0016] Figure 3 This is a schematic diagram of the structure of the optoelectronic device provided in the embodiments of this application.

[0017] Component symbol explanation:

[0018] 100. Optoelectronic device; 20. Anode; 80. Hole injection layer; 40. Hole transport layer; 50. Light-emitting layer; 60. Electron transport layer; 70. Cathode; 90. Nanoparticle; 91. Core; 92. Shell. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] 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.

[0021] 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, a+b, a+c, b+c, or a+b+c, where a, b, and c can be single or multiple.

[0022] In this application, another layer is formed "on" a certain layer. The term "on" is a broad concept and can mean that the formed other layer is adjacent to a certain layer, or that there are other spacer structures between the other layer and the certain layer. For example, a second electrode is formed "on" the first charge carrier functional layer. The term "on" can mean that the formed second electrode is adjacent to the first charge carrier functional layer, or that there are other spacer structures between the second electrode and the first charge carrier functional layer, such as a light-emitting layer.

[0023] "Parts by weight" is a basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit mass, such as 1g, 1kg, 2g, 2kg, etc. If we say that component A has "a" parts by weight and component B has "b" parts by weight, it means the mass ratio of component A to component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike parts by weight, the sum of the parts by weight of all components is not limited to 100 parts.

[0024] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a 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 numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0025] Please see Figure 1 This application provides a nanoparticle 90, comprising a core 91 and a shell 92 covering the outer surface of the core 91. The core 91 is made of a single metal oxide, and the shell 92 is made of a doped metal oxide. The single metal oxide comprises a first metal element, and the doped metal oxide comprises a second metal element and a third metal element. The first metal element and the third metal element are independently selected from Group VIB, Group IIB, Group IIA, Group IVB, and Group IVA elements, respectively, and the second metal element is selected from Group IA and Group IIA elements.

[0026] In some embodiments, the first metal element in the core 91 is the same as the third metal element in the shell 92.

[0027] For example, the particle size of the core 91 is 3nm to 4nm, such as 3nm, 3.2nm, 3.5nm, 3.8nm, 4nm, etc.

[0028] For example, the thickness of the shell layer 92 is 1nm to 3nm, such as 1nm, 1.5nm, 2nm, 2.5nm, 3nm, etc. It should be noted that the reason for controlling the thickness of the shell layer 92 to 1nm to 3nm in this application is that holes can tunnel through the shell layer 92 at this thickness (1nm to 3nm), that is to say, the shell layer 92 of this thickness can passivate the surface defects of the core 91 without affecting the carrier transport performance of the core 91.

[0029] For example, the average particle size of the nanoparticles 90 is 4nm to 7nm, such as 4nm, 4.5nm, 5nm, 5.5nm, 6nm, etc.

[0030] In some embodiments, nanoparticles 90 can be used as hole injection layer materials. In this case, the first metal element is a group VIB element, and the second metal element includes at least one group IA and group IIA elements. Since the shell material of nanoparticles 90 can passivate defects on the surface of the core 91, it can reduce hole quenching at the interface between the hole injection layer and the hole transport layer, thereby improving the luminous efficiency and lifespan of optoelectronic devices.

[0031] For example, the first metal element may include at least one of tungsten (W) and molybdenum (Mo).

[0032] For example, the second metal element includes at least one of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), magnesium (Mg), and calcium (Ca).

[0033] In some embodiments, the single metal oxide includes WO3, and the doped metal oxide includes at least one of Li2WO4, Na2WO4, K2WO4, Rb2WO4, and Cs2WO4.

[0034] In some embodiments, the single metal oxide includes MoO3, and the doped metal oxide includes at least one of Li2MoO4, Na2MoO4, K2MoO4, Rb2MoO4, and Cs2MoO4.

[0035] In some embodiments, the single metal oxide includes MoO3, and the doped metal oxide includes at least one of Li2MoO4, Na2MoO4, K2MoO4, Rb2MoO4, and Cs2MoO4.

[0036] In other embodiments, nanoparticles 90 can be used as electron transport layer materials. In this case, the first metal element includes at least one of group IIB, group IIA, group IVB and group IVA elements, and the second metal element includes at least one of group IA and group IIA elements. Since the shell material of nanoparticles 90 can passivate defects on the surface of the core 91 (such as oxygen vacancies and lattice dislocation defects), it can reduce exciton quenching at the interface between the electron transport layer and the light-emitting layer, thereby improving the luminous efficiency and lifespan of optoelectronic devices.

[0037] For example, the first metal element may include at least one of zinc (Zn), barium (Ba), titanium (Ti), and tin (Sn).

[0038] For example, the second metal element may include at least one of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

[0039] In some embodiments, the single metal oxide includes ZnO, and the doped metal oxide includes at least one of Li2ZnO2, Na2ZnO2, K2ZnO2, and Rb2ZnO2.

[0040] In some embodiments, the single metal oxide includes BaO, and the doped metal oxide includes at least one of Li2BaO2, Na2BaO2, K2BaO2, and Rb2BaO2.

[0041] In some embodiments, the single metal oxide includes TiO2, and the doped metal oxide includes at least one of Li2TiO3, Na2TiO3, K2TiO3, and Rb2TiO3.

[0042] In some embodiments, the single metal oxide includes SnO2, and the doped metal oxide includes at least one of LiSnO3, NaSnO3, KSnO3, and RbSnO3.

[0043] Please see Figure 2 See also Figure 1 This application provides a method for preparing nanoparticles, comprising:

[0044] S100 provides a core 91, the material of which comprises a single metal oxide, the single metal oxide comprising a first metal element.

[0045] S200, a shell material is coated on the surface of the core 91. The shell material includes a doped metal oxide, which includes a second metal element and a third metal element, to obtain nanoparticles 90. The nanoparticles 90 include a core 91 and a shell 92 covering the outer surface of the core 91. The first metal element and the third metal element are independently selected from Group VIB, Group IIB, Group IIA, Group IVB, and Group IVA elements, respectively. The second metal element is selected from Group IA and Group IIA elements.

[0046] For example, when the prepared nanoparticles 90 are hole injection layer materials, that is, when the first metal element includes a group VIB element, the second metal element includes at least one of a group IA element and a group IIA element.

[0047] For example, the provision of kernel 91 includes:

[0048] A first metal salt, thiourea, and water are mixed to obtain a first mixture. The first mixture is then heated at a temperature of 230°C to 260°C (e.g., 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, 260°C, etc.) for 16 to 20 hours (e.g., 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, etc.) to obtain a core. The metal element in the first metal salt is a group VIB element.

[0049] For example, the first metal salt is a halide salt. For example, the halogen in the halide salt includes at least one of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0050] For example, in the first mixture, the molar ratio of the first metal salt to the thiourea is 1:(10-12), such as 1:10, 1:10.5, 1:11, 1:11.5, 1:12, etc.

[0051] In some embodiments, the first metal salt is tungsten chloride. Under high temperature conditions of 230°C to 260°C, the first metal salt (tungsten chloride), thiourea, and water undergo a chemical reaction to generate WO3 particles, which are the core 91.

[0052] Exemplarily, the surface coating material of the core 91 includes:

[0053] A first mixture containing core 91, a second metal salt, and a third metal salt are mixed to obtain a second mixture. The second mixture is heated at a temperature of 260°C to 300°C (e.g., 260°C, 270°C, 280°C, 290°C, 300°C, etc.) for 4 hours to 8 hours (e.g., 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc.) to obtain the nanoparticles 90. The metal element in the second metal salt includes a Group VIB element, and the metal element in the third metal salt includes at least one of a Group IA element and a Group IIA element.

[0054] For example, the second metal salt may be a halide salt, and the third metal salt may be a halide salt. For example, the halogen in the halide salt includes at least one of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0055] For example, in the second mixture, the molar ratio of the second metal salt to the third metal salt is 1:(2 to 2.5), such as 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, etc.

[0056] In some embodiments, the second metal salt is tungsten chloride and the third metal salt is lithium chloride. Under high temperature conditions of 260°C to 300°C, the second metal salt (tungsten chloride), the third metal salt (lithium chloride), the unreacted thiourea remaining in the first mixture, and water undergo a chemical reaction to generate Li2WO4, which constitutes the shell layer 92.

[0057] For example, after obtaining the nanoparticles 90, a second mixture containing the second particles is mixed with a precipitant to obtain a third mixture, and the nanoparticles 90 precipitated at the bottom of the third mixture are collected.

[0058] For example, the precipitant is ethyl acetate. It should be noted that the working principle of ethyl acetate as a precipitant is as follows: Since ethyl acetate is slightly soluble in water, when a precipitant is added to the second mixture, the solvent system for the nanoparticles 90 in the resulting third mixture is a mixture of ethyl acetate and water. Because the ligands (e.g., hydroxyl and chloride ions) on the surface of the nanoparticles 90 are insoluble in ethyl acetate, the nanoparticles 90 have poor solubility in the solvent system (the mixture of ethyl acetate and water) and gradually settle to the bottom of the solvent system.

[0059] For example, the mass ratio of the precipitant to the water in the second mixture is 1:(1 to 10), such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0060] For example, when the prepared nanoparticles 90 are electron transport layer materials, that is, when the first metal element includes at least one of group IIB, group IIA, group IVB, and group IVA elements, the second metal element includes at least one of group IA and group IIA elements.

[0061] For example, the provision of kernel 91 includes:

[0062] A first metallic element, an alkaline substance, an oxidizing agent, and water are mixed to dissolve the first metallic element, resulting in a first solution.

[0063] An acidic substance is added to the first solution to obtain a second solution. The second solution is then heated and dried to obtain a gel-like substance.

[0064] The gelatinous substance was dissolved in water to obtain a third solution;

[0065] The third solution was heated at a temperature of 180℃ to 220℃ for 3 to 5 hours to obtain core 91.

[0066] Exemplarily, the surface coating material of the core 91 includes:

[0067] The third solution containing the core 91 is mixed with a fourth metal salt to obtain a mixed system. The mixed system is heated at a temperature of 260°C to 300°C for 4 to 6 hours to obtain the nanoparticles. The metal element in the fourth metal salt includes at least one element from Group IA and Group IIA.

[0068] In some embodiments, the first metallic element is titanium, the alkaline substance is ammonia, the oxidant is hydrogen peroxide, the acidic substance is citric acid, and the fourth metal salt is lithium acetate. In this case, the core 91 of the obtained nanoparticle 90 is TiO2, and the shell 92 is Li2TiO3.

[0069] In some embodiments, the third solution is heated at 200°C for 4 hours to obtain core 91.

[0070] In some embodiments, the mixture is heated at 280°C for 5 hours to obtain the nanoparticles.

[0071] This application also provides a thin film comprising nanoparticles 90 as described in any of the above embodiments or nanoparticles 90 prepared by any of the above embodiments.

[0072] For example, the thickness of the film is 10nm-100nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.

[0073] For example, the thin film can be applied to an optoelectronic device 100 as a hole injection layer.

[0074] Please see Figure 3 This application provides an optoelectronic device 100, including a cathode 70 and an anode 20 disposed opposite to each other, and a functional layer disposed between the cathode 70 and the anode 20. The material of the functional layer includes nanoparticles as described in any of the above embodiments or nanoparticles prepared by the method described in any of the above embodiments.

[0075] Please see Figure 3 The functional layer includes a hole injection layer 80 and / or an electron transport layer 60. At least one of the materials of the hole injection layer 80 and / or the electron transport layer 60 includes nanoparticles from any of the above embodiments or nanoparticles prepared by the preparation method in any of the above embodiments.

[0076] Please see Figure 3 The functional layer also includes a light-emitting layer 50.

[0077] Optionally, the material of the light-emitting layer 50 includes one or more of organic light-emitting materials and quantum dot light-emitting materials. The organic light-emitting materials include one or more of the following: 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 fluorescence materials, TTA materials, thermally activated delayed materials, polymers containing BN covalent bonds, hybrid local charge transfer excited state materials, excitopolymer light-emitting materials, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, and polyfluorene and its derivatives.The quantum dot luminescent material comprises one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots are each independently selected from one or more 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, CdSTe, ZnSeS, ZnSeTe, and ZnO. One or more of the following compounds: STe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe, wherein the group IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, and PbSeS. PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, and the III-V compound includes one or more 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, GaAlNP, and GaAlN. One or more of As, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb, wherein the I-III-VI group compounds include one or more of CuInS2, CuInSe2, and AgInS2; wherein the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors, wherein the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation, including CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of them.

[0078] Please see Figure 3 The functional layer also includes a hole transport layer 40.

[0079] Optionally, the material of the hole transport layer 40 includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], 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, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), 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-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiron NPB, Poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-di(carbazole-9-yl)benzene, polyaniline, polypyrrole, poly(p-)phenylenevinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4 '-Bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO, or one or more of these.

[0080] Please see Figure 3 The functional layer also includes an electronic transport layer 60.

[0081] Optionally, the material of the electron transport layer 60 includes at least one of fullerene, fullerene derivative, fullerene, metal oxide, and doped metal oxide. The fullerene derivative includes methyl [6,6]-phenyl-C61-butyrate. The metal oxide is selected from at least one of ZnO, BaO, TiO2, and SnO2. The metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2, and SnO2, and the doping element is selected from at least one of Al, Mg, Li, In, and Ga.

[0082] Optionally, the anode 20 and cathode 70 each independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal element electrode, or an alloy electrode. The material of the doped metal oxide particle electrode includes 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 composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the metal element electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba.

[0083] For example, the thickness of the hole transport layer 40 is 10nm-60nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, etc.

[0084] For example, the thickness of the electron transport layer 60 is 10nm-60nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, etc.

[0085] For example, the thickness of the anode 20 is 10nm-100nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.

[0086] For example, the thickness of the cathode 70 is 10nm-100nm, such as 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, etc.

[0087] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0088] Particle Example 1

[0089] A nanoparticle, the preparation method of which includes:

[0090] Step 11: Mix 2 mmol of the first metal salt (tungsten chloride WCl6), 20 mmol of thiourea (CS(NH2)2) and 35 ml of deionized water to obtain the first mixture. Transfer the first mixture to a 50 ml Teflon-lined stainless steel high-pressure reactor and heat it at 245°C for 18 hours to generate the core (WO3 particles).

[0091] Step 12: After cooling the first mixture containing the core (WO3 particles) to room temperature, open the reactor and add 1 mmol of the second metal salt (tungsten chloride WCl6) and 2 mmol of the third metal salt (anhydrous lithium chloride LiCl) to obtain the second mixture. Heat the second mixture at 280°C for 6 hours to generate nanoparticles. The nanoparticles include the core (WO3 particles) and the shell (Li2WO4) covering the surface of the core (WO3 particles).

[0092] Step 13: After cooling the second mixture containing nanoparticles to room temperature, open the reaction vessel and add 35 ml of ethyl acetate. After the nanoparticles precipitate, collect the precipitate by centrifugation. Finally, disperse the collected nanoparticles in ethanol for later use. The average particle size of the nanoparticles is 5 nm.

[0093] Particle Example 2

[0094] A nanoparticle, which differs from the nanoparticle in Example 1 in that:

[0095] In step 11, the first metal salt added is molybdenum pentachloride (MoCl5), and the resulting core is MoO3;

[0096] In step 12, the second metal salt added is molybdenum pentachloride (MoCl5), and the generated nanoparticles include a core (MoO3 particles) and a shell (Li2MoO4) covering the surface of the core (MoO3 particles). The average particle size of the nanoparticles is 5.5 nm.

[0097] Particle Example 3

[0098] A nanoparticle, which differs from the nanoparticle in Example 1 in that:

[0099] In step 12, the third metal salt added is anhydrous sodium chloride (NaCl), and the generated nanoparticles include a core (WO3 particles) and a shell (Na2WO4) covering the surface of the core (WO3 particles). The average particle size of the nanoparticles is 4.5 nm.

[0100] Particle Example 4

[0101] A nanoparticle, which differs from the nanoparticle in Example 1 in that:

[0102] In step 12, the third metal salt added is anhydrous rubidium chloride (RbCl), and the generated nanoparticles include a core (WO3 particles) and a shell (Rb2WO4) covering the surface of the core (WO3 particles). The average particle size of the nanoparticles is 6 nm.

[0103] Particle Example 5

[0104] A nanoparticle, which differs from the nanoparticle in Example 1 in that:

[0105] In step 12, the third metal salt added is anhydrous cesium chloride (CsCl), and the generated nanoparticles include a core (WO3 particles) and a shell (Cs2WO4) covering the surface of the core (WO3 particles). The average particle size of the nanoparticles is 5.5 nm.

[0106] Particle Example 6

[0107] A nanoparticle, the preparation method of which includes:

[0108] 5 mmol of titanium powder was dissolved in a cooled mixture of 5 mL of 30% ammonia solution and 20 mL of 30% hydrogen peroxide. After dissolution, 5 mmol of citric acid was added to the mixture, and the solution was evaporated and dried at 80 °C to form a yellow or orange gel. The gel was then dissolved in 10 mL of pure water to obtain a transparent aqueous solution with a pH of approximately 6. The aqueous solution was transferred to a 50 mL Teflon-lined stainless steel autoclave and heated at 200 °C for 4 h. After cooling, 10 mmol of lithium acetate was added, and the mixture was heated at 280 °C for 5 h. After cooling to room temperature, excess ethyl acetate was added to the reaction solution to precipitate TiO2 / Li2TiO3 nanoparticles. The precipitate (TiO2 / Li2TiO3 nanoparticles) was obtained by centrifugation and then redispersed in ethanol for device fabrication. The average particle size of the nanoparticles was 6 nm.

[0109] Particle Comparative Example 1

[0110] A nanoparticle, the preparation method of which includes:

[0111] Step 10: Mix 2 mmol of metal salt (tungsten chloride WCl6), 20 mmol of thiourea (CS(NH2)2) and 35 ml of deionized water to obtain a mixture. Transfer the mixture to a 50 ml Teflon-lined stainless steel high-pressure reactor and heat at 245 °C for 18 hours to generate nanoparticles (WO3 particles).

[0112] Step 20: After cooling the mixture containing nanoparticles (WO3 particles) to room temperature, open the reaction vessel and add 35 ml of ethyl acetate. After the nanoparticles (WO3 particles) precipitate, collect the precipitate by centrifugation. Finally, disperse the collected nanoparticles (WO3 particles) in ethanol for later use. The average particle size of the nanoparticles (WO3 particles) is 5 nm.

[0113] As can be seen, compared with particle example 1, the nanoparticles prepared in particle comparative example 1 do not contain a shell and are composed only of WO3 particles.

[0114] Particle Comparative Example 2

[0115] A TiO2 nanoparticle, the preparation method of which includes:

[0116] 5 mmol of titanium powder was dissolved in a cooled mixture of 5 mL of 30% ammonia solution and 20 mL of 30% hydrogen peroxide. After dissolving the titanium powder, 5 mmol of citric acid was added to the mixture. The solution was then evaporated and dried at 80 °C to form a yellow or orange gel-like substance. The gel-like substance was then dissolved in 10 mL of pure water to obtain a transparent aqueous solution with a pH of approximately 6. The aqueous solution was transferred to a 50 mL Teflon-lined stainless steel autoclave and heated at 200 °C for 4 h. After the autoclave cooled, ethyl acetate was added to precipitate TiO2 nanoparticles. The precipitate (TiO2 nanoparticles) was obtained by centrifugation and then redispersed in ethanol. The average particle size of the nanoparticles was 6 nm.

[0117] As can be seen, compared with particle example 6, the nanoparticles prepared in particle comparative example 1 do not contain a shell of Li2TiO3, but are composed only of TiO2 nanoparticles.

[0118] Thin Film Example 1

[0119] A thin film, the preparation method of which includes:

[0120] Spin-coating a nanoparticle solution, comprising the nanoparticles prepared in Example 1 and ethanol, with a concentration of 20 mg / ml, and heating at 80°C for 5 minutes, yields a film with a thickness of 30 nm.

[0121] Thin Film Example 2

[0122] A thin film, which differs from the thin film of Example 1 in that:

[0123] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Example 2, and the thickness of the thin film is 34 nm.

[0124] Thin Film Example 3

[0125] A thin film, which differs from the thin film of Example 1 in that:

[0126] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Example 3, and the thickness of the thin film is 32 nm.

[0127] Thin Film Example 4

[0128] A thin film, which differs from the thin film of Example 1 in that:

[0129] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Example 4, and the thickness of the thin film is 35 nm.

[0130] Thin Film Example 5

[0131] A thin film, which differs from the thin film of Example 1 in that:

[0132] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Example 5, and the thickness of the thin film is 33 nm.

[0133] Thin Film Example 6

[0134] A thin film, which differs from the thin film of Example 1 in that:

[0135] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Example 6, and the thickness of the thin film is 31 nm.

[0136] Thin Film Comparative Example 1

[0137] A thin film, which differs from the thin film of Example 1 in that:

[0138] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Comparative Example 1, and the thickness of the thin film is 30 nm.

[0139] Thin Film Comparative Example 2

[0140] A thin film, which differs from thin film example 6 in that:

[0141] In the thin film preparation method, the nanoparticles in the nanoparticle solution are the nanoparticles prepared in Comparative Example 2, and the thickness of the thin film is 31 nm.

[0142] Device Comparison Example 1

[0143] A photoelectric device, the method for fabricating which includes:

[0144] Step S1: The cleaned anode (ITO, 80nm) is treated with UVO (ultraviolet ozone) for 15 minutes, and a first thin film is formed on the anode according to the method of thin film comparative example 1. The first thin film constitutes a hole injection layer with a thickness of 30nm.

[0145] Step S2: Spin-coat TFB onto the hole injection layer and heat at 200°C for 30 minutes to obtain a hole transport layer with a thickness of 25nm.

[0146] Step S3: Spin-coat quantum dots (CdSe / ZnS core-shell quantum dots, Sigma catalog number 790192, fluorescence 620nm) onto the hole transport layer, heat at 100℃ for 8 minutes to obtain the light-emitting layer with a thickness of 30nm.

[0147] Step S4: Form a second thin film on the light-emitting layer according to the method of thin film comparative example 2. The second thin film constitutes an electron transport layer with a thickness of 31 nm.

[0148] Step S5: Deposit Ag on the electron transport layer to obtain a cathode with a thickness of 100 nm, thus obtaining an optoelectronic device.

[0149] Device Example 1

[0150] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0151] In step S1, a first thin film is formed on the anode according to the method of thin film embodiment 1. The first thin film constitutes a hole injection layer with a thickness of 30 nm.

[0152] Device Example 2

[0153] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0154] In step S1, a first thin film is formed on the anode according to the method of thin film embodiment 2. The first thin film constitutes a hole injection layer with a thickness of 34 nm.

[0155] Device Example 3

[0156] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0157] In step S1, a first thin film is formed on the anode according to the method of thin film embodiment 3. The first thin film constitutes a hole injection layer with a thickness of 32 nm.

[0158] Device Example 4

[0159] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0160] In step S1, a first thin film is formed on the anode according to the method of thin film embodiment 4. The first thin film constitutes a hole injection layer with a thickness of 35 nm.

[0161] Device Example 5

[0162] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0163] In step S1, a first thin film is formed on the anode according to the method of thin film embodiment 5. The first thin film constitutes a hole injection layer with a thickness of 33 nm.

[0164] Device Example 6

[0165] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0166] In step S4, a second thin film is formed on the light-emitting layer according to the method of thin film embodiment 6. The second thin film constitutes an electron transport layer with a thickness of 31 nm.

[0167] Device Example 7

[0168] This embodiment provides an optoelectronic device, the fabrication method of which differs from that of Comparative Example 1 in that:

[0169] In step S1, a first thin film is formed on the anode according to the method of thin film embodiment 1. The first thin film constitutes a hole injection layer with a thickness of 30 nm.

[0170] In step S4, a second thin film is formed on the light-emitting layer according to the method of thin film embodiment 6. The second thin film constitutes an electron transport layer with a thickness of 31 nm.

[0171] Thin film performance testing:

[0172] (1) The fluorescence lifetime of the films prepared in Thin Film Examples 1-5 and Thin Film Comparative Example 1 was tested. The test method is as follows:

[0173] The thin films of Examples 1-5 and Comparative Example 1 were applied to an optoelectronic device. The optoelectronic device included an anode (ITO), a thin film (hole injection layer), and a hole transport layer (TFB). The fluorescence lifetime of the hole transport layer (TFB) in the optoelectronic device was measured at 450 nm using a fluorescence lifetime spectrometer (FluoTime 300, PicoQuant). Time-resolved fluorescence lifetime decay and spectra were obtained by acquiring time-correlated single-photon counting data. A femtosecond pulsed diode laser (LDH-P-FA-530B, PicoQuant) with a repetition rate of 800 kHz was used to excite the sample. The collected photons were acquired using a multiplier tube (PMA-C-192, PicoQuant) connected to a time-correlated single-photon counting plate (TimeHarp 260Pico, PicoQuant). The overall instrument response function was approximately 200 ps (full width at half maximum). To reconstruct the time-resolved fluorescence lifetime spectrum, fluorescence decay curves dependent on the detection wavelength were acquired at 5 nm wavelength intervals. All fluorescence decay curves were collected at fixed acquisition times. The obtained curves were fitted with single or multiple natural exponential decay to obtain the corresponding decay ratio α for different decay periods. i and fluorescence lifetime τ i Then, calculate the average fluorescence lifetime using the following formula.

[0174] The performance test results of thin film Examples 1-5 and Thin film Comparative Example 1 are shown in Table 1:

[0175] Table 1

[0176]

[0177]

[0178] As can be seen from Table 2:

[0179] The fluorescence lifetimes of the thin films prepared in Examples 1-5 as hole transport layers (TFBs) in optoelectronic devices are all greater than those of the thin films prepared in Comparative Example 1. The difference between Examples 1-5 and Comparative Example 1 is that the material of the thin film (hole injection layer) prepared in Comparative Example 1 is WO3 particles, while the material of the thin films (hole injection layers) prepared in Examples 1-5 are all core-shell structured nanoparticles, with the core being WO3 particles and the shell being doped metal oxides. This indicates that by coating the surface of WO3 particles with doped metal oxides, the defects on the surface of the WO3 particles can be passivated. When the resulting core-shell structured nanoparticles are used to prepare the thin film (hole injection layer), they can weaken hole quenching at the interface between the thin film (hole injection layer) and the hole transport layer (TFB), thereby extending the fluorescence lifetime of the hole transport layer (TFB).

[0180] (2) The performance of the films prepared in Thin Film Example 6 and Thin Film Comparative Example 2 was tested using the following methods:

[0181] The thin films of Thin Film Example 6 and Thin Film Comparative Example 2 were applied to an optoelectronic device. The optoelectronic device included an anode (ITO), a thin film (electron transport layer), and a quantum dot emitting layer (CdSe / ZnS core-shell quantum dots). The fluorescence lifetime of the quantum dot emitting layer in the optoelectronic device at 620 nm was measured using a fluorescence lifetime spectrometer (FluoTime 300, PicoQuant). Time-resolved fluorescence lifetime decay and spectra were obtained by acquiring time-correlated single-photon counting data. To excite the sample, a femtosecond pulsed diode laser (LDH-P-FA-530B, PicoQuant) with a repetition rate of 800 kHz was used. The collected photons were acquired using a multiplier tube (PMA-C-192, PicoQuant) connected to a time-correlated single-photon counting plate (TimeHarp 260Pico, PicoQuant). The overall instrument response function was approximately 200 ps (full width at half maximum). To reconstruct the time-resolved fluorescence lifetime spectrum, fluorescence decay curves dependent on the detection wavelength were acquired at 5 nm wavelength intervals. All fluorescence decay curves were collected at fixed acquisition times. The obtained curves were fitted with single or multiple natural exponential decay to obtain the corresponding decay ratio α for different decay periods. i and fluorescence lifetime τ i Then, calculate the average fluorescence lifetime using the following formula.

[0182] The performance test results of thin film Example 6 and thin film Comparative Example 2 are shown in Table 2:

[0183] Table 2

[0184]

[0185] As can be seen from Table 2:

[0186] When the thin film prepared in Thin Film Example 6 is applied to an optoelectronic device, the fluorescence lifetime of the quantum dot emitting layer is greater than that of the thin film prepared in Thin Film Comparative Example 2. The difference between Thin Film Example 6 and Thin Film Comparative Example 2 is that the material of the thin film (electron transport layer) prepared in Thin Film Comparative Example 2 is TiO2 particles, while the material of the thin film (electron transport layer) prepared in Thin Film Example 6 is nanoparticles with a core-shell structure (where the core is TiO2 particles and the shell is a doped metal oxide Li2TiO3). This indicates that by coating the surface of TiO2 particles with a doped metal oxide, the defects on the surface of TiO2 particles can be passivated. When the nanoparticles with a core-shell structure are used to prepare the thin film (electron transport layer), they can weaken the exciton quenching at the interface between the thin film (electron transport layer) and the quantum dot emitting layer, thereby extending the fluorescence lifetime of the quantum dot emitting layer.

[0187] Device performance testing:

[0188] The devices prepared in Device Examples 1-7 and Device Comparative Example 1 were subjected to performance testing, and the testing methods are as follows:

[0189] (1) External quantum efficiency (EQE) (%): Measured using optical testing instruments (F-STAR Optical Measurement Systems).

[0190] (2) Device lifetime testing: Under constant current (2mA) driving, the electroluminescence lifetime analysis of each light-emitting device is performed using lifetime testing equipment. The time required for each light-emitting device to decay from the maximum brightness to 95% (T95,h) is recorded. The time required for each light-emitting device to decay from 100% to 95% at a brightness of 1000nit (T95@1000nit,h) is calculated by the decay fitting formula.

[0191] The device performance test results are shown in Table 3:

[0192] Table 3

[0193]

[0194] As can be seen from Table 3:

[0195] The external quantum efficiency (EQE) and lifetime (T95@1000nit) of the devices prepared in Device Examples 1-5 are both greater than those of the device prepared in Comparative Example 1. The difference between Device Examples 1-5 and Comparative Example 1 is that the hole injection layer in Comparative Example 1 is made of WO3 particles, while the hole injection layer in Device Examples 1-5 is made of core-shell nanoparticles, with the core being WO3 particles and the shell being a doped metal oxide. This indicates that by coating the surface of WO3 particles with doped metal oxides, defects on the surface of the WO3 particles can be passivated. When the resulting core-shell nanoparticles are used as hole injection layer materials in optoelectronic devices, they can reduce hole quenching at the interface between the thin-film hole injection layer and the hole transport layer, thereby improving the luminous efficiency and lifetime of the optoelectronic device.

[0196] The external quantum efficiency (EQE) and lifetime (T95@1000nit) of the device prepared in Device Example 6 are both greater than those of the device prepared in Comparative Example 1. The difference between Device Example 6 and Comparative Example 1 is that the electron transport layer material in Comparative Example 1 is TiO2 particles, while the electron transport layer material in Device Examples 1-6 is nanoparticles with a core-shell structure, wherein the core is TiO2 particles and the shell is a doped metal oxide. This indicates that by coating the surface of TiO2 particles with doped metal oxide, the defects on the surface of TiO2 particles can be passivated. When the resulting nanoparticles with a core-shell structure are used as electron transport layer materials in optoelectronic devices, they can reduce exciton quenching at the interface between the device (electron transport layer) and the quantum dot luminescent layer, thereby improving the luminous efficiency and lifetime of the optoelectronic device.

[0197] The external quantum efficiency (EQE) and lifetime (T95@1000nit) of the device in Device Example 1 and Device Example 6 are both lower than those of the device in Device Example 7. The improvement of Device Example 1 compared to the prior art (Device Comparative Example 1) is that the hole injection layer material uses nanoparticles with a core-shell structure (where the core is a WO3 particle and the shell is a doped metal oxide); the improvement of Device Example 6 compared to the prior art (Device Comparative Example 1) is that the electron transport layer material uses nanoparticles with a core-shell structure (…). The core of the device is TiO2 particles, and the shell is a doped metal oxide. The improvement of device embodiment 7 compared with the prior art (device comparative example 1) is that the hole injection layer is made of nanoparticles with a core-shell structure (the core is WO3 particles, and the shell is a doped metal oxide), and the electron transport layer is made of nanoparticles with a core-shell structure (the core is TiO2 particles, and the shell is a doped metal oxide). This shows that by using nanoparticles with a core-shell structure for both the hole injection layer and the electron transport layer, the carrier transport performance of the optoelectronic device can be improved more effectively, thereby improving the luminous efficiency and lifespan of the optoelectronic device.

[0198] The nanoparticles, their preparation methods, thin films, and optoelectronic devices provided in 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, and the descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A nanoparticle, characterized in that, It includes a core and a shell covering the outer surface of the core. The core is made of a single metal oxide, and the shell is made of a doped metal oxide. The single metal oxide includes a first metal element, and the doped metal oxide includes a second metal element and a third metal element. The first metal element and the third metal element are independently selected from group VIB, group IIB, group IIA, group IVB, and group IVA elements, respectively, and the second metal element is selected from group IA and group IIA elements.

2. The nanoparticles according to claim 1, characterized in that, The first metallic element in the core is the same as the third metallic element in the shell; and / or, The average particle size of the core is 3nm to 4nm; and / or, The average thickness of the shell is 1 nm to 3 nm; and / or, The average particle size of the nanoparticles is 4 nm to 7 nm.

3. The nanoparticles according to claim 1, characterized in that, The first metallic element includes a group VIB element, and the second metallic element includes at least one group IA element and a group IIA element.

4. The nanoparticles according to claim 3, characterized in that, The first metallic element includes at least one of tungsten and molybdenum; and / or, The second metallic element includes at least one of lithium, sodium, potassium, rubidium, cesium, magnesium, and calcium; Optionally, the single metal oxide includes WO3, and the doped metal oxide includes at least one of Li2WO4, Na2WO4, K2WO4, Rb2WO4, and Cs2WO4; and / or, the single metal oxide includes MoO3, and the doped metal oxide includes at least one of Li2MoO4, Na2MoO4, K2MoO4, Rb2MoO4, and Cs2MoO4.

5. The nanoparticles according to claim 1, characterized in that, The first metallic element includes at least one of Group IIB, Group IIA, Group IVB, and Group IVA elements, and the second metallic element includes at least one of Group IA and Group IIA elements.

6. The nanoparticles according to claim 5, characterized in that, The first metallic element is zinc, barium, titanium, or tin; and / or, The second metallic element is lithium, sodium, potassium, rubidium, or cesium; Optionally, the single metal oxide comprises ZnO, and the doped metal oxide comprises at least one of Li₂ZnO₂, Na₂ZnO₂, K₂ZnO₂, and Rb₂ZnO₂; and / or, the single metal oxide comprises BaO, and the doped metal oxide comprises at least one of Li₂BaO₂, Na₂BaO₂, K₂BaO₂, and Rb₂BaO₂; and / or, the single metal oxide comprises TiO₂, and the doped metal oxide comprises at least one of Li₂TiO₃, Na₂TiO₃, K₂TiO₃, and Rb₂TiO₃; and / or, the single metal oxide comprises SnO₂, and the doped metal oxide comprises at least one of LiSnO₃, NaSnO₃, KSnO₃, and RbSnO₃.

7. A method for preparing nanoparticles, characterized in that, include: A core is provided, the core material comprising a single metal oxide, the single metal oxide comprising a first metal element; A shell material is coated on the surface of the core. The shell material includes a doped metal oxide, which includes a second metal element and a third metal element, to obtain nanoparticles. The nanoparticles include a core and a shell coating the outer surface of the core. The first metal element and the third metal element are independently selected from Group VIB, Group IIB, Group IIA, Group IVB, and Group IVA elements, respectively, and the second metal element is selected from Group IA and Group IIA elements.

8. The method for preparing nanoparticles according to claim 7, characterized in that, When the first metallic element includes a Group VIB element, and the second metallic element includes at least one of a Group IA element and a Group IIA element. The provided kernel includes: A first metal salt, thiourea, and water are mixed to obtain a first mixture. The first mixture is heated at a temperature of 230°C to 260°C for 16 to 20 hours to obtain a core. The metal element in the first metal salt is a group VIB element. The surface coating material of the core includes: A first mixture containing a core, a second metal salt, and a third metal salt are mixed to obtain a second mixture. The second mixture is heated at a temperature of 260°C to 300°C for 4 to 8 hours to obtain the nanoparticles. The metal element in the second metal salt includes a group VIB element, and the metal element in the third metal salt includes at least one group IA element and a group IIA element.

9. The method for preparing nanoparticles according to claim 7, characterized in that, When the first metallic element includes at least one of Group IIB, Group IIA, Group IVB, and Group IVA elements, and the second metallic element includes at least one of Group IA and Group IIA elements... The provided kernel includes: A first metallic element, an alkaline substance, an oxidizing agent, and water are mixed to dissolve the first metallic element, resulting in a first solution. An acidic substance is added to the first solution to obtain a second solution. The second solution is then heated and dried to obtain a gel-like substance. The gelatinous substance was dissolved in water to obtain a third solution; The third solution is heated at 180℃~220℃ for 3 to 5 hours to obtain the core. The surface coating material of the core includes: A third solution containing the core is mixed with a fourth metal salt to obtain a mixed system. The mixed system is heated at a temperature of 260°C to 300°C for 4 to 6 hours to obtain the nanoparticles. The metal element in the fourth metal salt includes at least one element from Group IA and Group IIA.

10. A thin film, characterized in that, Nanoparticles include those prepared by the method of any one of claims 1-6 or claims 7-9.

11. An optoelectronic device, characterized in that, It includes a cathode and an anode disposed opposite to each other and a functional layer disposed between the cathode and the anode, wherein the material of the functional layer includes nanoparticles as described in any one of claims 1-6 or nanoparticles prepared by the method of preparing nanoparticles as described in any one of claims 7-9.

12. The optoelectronic device as described in claim 11, characterized in that, The functional layer includes a hole injection layer and / or an electron transport layer, and at least one of the materials of the hole injection layer and / or the electron transport layer includes nanoparticles prepared by the method of any one of claims 1-6 or claims 7-9.

13. The optoelectronic device as described in claim 11, characterized in that, The functional layer includes a light-emitting layer; Optionally, the material of the light-emitting layer includes one or more of organic light-emitting materials and quantum dot light-emitting materials. The organic light-emitting materials include one or more of the following: 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 fluorescence materials, TTA materials, thermally activated delayed materials, polymers containing BN covalent bonds, hybrid local charge transfer excited state materials, excitopolymer light-emitting materials, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, and polyfluorene and its derivatives.The quantum dot luminescent material comprises one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots are each independently selected from one or more 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, CdSTe, ZnSeS, ZnSeTe, and ZnO. One or more of the following compounds: STe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe, wherein the group IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, and PbSeS. PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, and the III-V compound includes one or more 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, GaAlNP, and GaAlN. One or more of As, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb, wherein the I-III-VI group compounds include one or more of CuInS2, CuInSe2, and AgInS2; wherein the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors, wherein the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation, including CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; and / or, The functional layer includes a hole transport layer; Optionally, the material of the hole transport layer includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], 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, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)spiro, N,N'-Di(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiron NPB, poly(amino) Phenylacetylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-di(carbazole-9-yl)benzene, polyaniline, polypyrrole, poly(p)phenylenevinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(phenylenevinylene) (p-Carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or, The functional layer includes an electronic transport layer; Optionally, the material of the electron transport layer includes at least one selected from fullerene, fullerene derivative, fullerene, metal oxide, and doped metal oxide, wherein the fullerene derivative includes methyl [6,6]-phenyl-C61-butyrate, the metal oxide is selected from at least one selected from ZnO, BaO, TiO2, and SnO2, and the doping element is selected from at least one selected from Al, Mg, Li, In, and Ga; and / or, The anode and cathode each independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal element electrode, or an alloy electrode. The material of the doped metal oxide particle electrode includes 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 composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the metal element electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba.

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