Composite material and preparation method thereof, photoelectric device and display device

Abstract

The invention discloses a composite material and a preparation method thereof, a photoelectric device and a display device. The composite material comprises a core and a shell layer coating the surface of the core, the material of the core comprises N-type inorganic nanoparticles, and the material of the shell layer comprises montmorillonite nanosheets. According to the technical scheme provided by the invention, the surface of the N-type inorganic nanoparticle is coated with a layer of montmorillonite nanosheet, so that the agglomeration of the N-type inorganic nanoparticle is limited, the N-type inorganic nanoparticle and the external environment are effectively isolated, the N-type inorganic nanoparticle is prevented from reacting with water and oxygen in the environment, the influence of a heat effect on the material is also avoided, and the service life of the material is prolonged. Therefore, the stability of the material is effectively improved; and meanwhile, the electron injection performance of the N-type inorganic nanoparticles can be reduced, so that the N-type inorganic nanoparticles can be suitable for occasions with low electron injection requirements.

Description

Technical Field

[0001] This application relates to the field of semiconductor materials, and particularly to a composite material, a preparation method thereof, an optoelectronic device, and a display device. Background Art

[0002] An N-type semiconductor material refers to a semiconductor material having electron transport or electron injection properties, such as zinc oxide nanoparticles, titanium oxide nanoparticles, zirconium oxide nanoparticles, or doped materials of the above nanoparticles.

[0003] At room temperature, N-type semiconductor materials are prone to agglomeration, and under the influence of the external environment (such as electric field, temperature, water oxygen, etc.), the stability of N-type semiconductor materials is poor, affecting the application of the materials. Summary of the Invention

[0004] In view of this, this application provides a composite material, a preparation method thereof, an optoelectronic device, and a display device.

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

[0006] In a first aspect, this application provides a composite material, including a core and a shell layer coated on the surface of the core. The material of the core includes N-type inorganic nanoparticles, and the material of the shell layer includes montmorillonite nanosheets.

[0007] Optionally, in some embodiments of this application, in the composite material, the mass percentage content of the montmorillonite nanosheets is less than or equal to 60%.

[0008] Optionally, in some embodiments of this application, the average thickness of the montmorillonite nanosheets is 0.5 - 5 nm.

[0009] Optionally, in some embodiments of this application, the average particle size of the composite material is 1 - 10 nm.

[0010] Optionally, in some embodiments of this application, the N-type inorganic nanoparticles include one or more of N-type metal oxides or doped N-type metal oxides. The N-type metal oxides include one or more of ZnO, TiO2, SnO2, ZrO2; the N-type metal oxides in the doped N-type metal oxides include one or more of ZnO, TiO2, SnO2, ZrO2, and the doping elements include one or more of Al, Mg, Li, In, Ga.

[0011] In a second aspect, this application also provides a preparation method of a composite material, including the following steps:

[0012] Provide montmorillonite, a cation source, a solvent, an anion source, a positively charged surface modifier, and a first polyol;

[0013] Mix the montmorillonite, the cation source and the solvent, and conduct a first reaction to form a first solution, where the first solution contains montmorillonite loaded with cations;

[0014] Treat the first solution to convert the montmorillonite loaded with cations into montmorillonite nanosheets loaded with cations;

[0015] Mix the montmorillonite nanosheets loaded with cations, the anion source, the positively charged surface modifier and the first polyol, and conduct a second reaction to obtain a composite material. The composite material includes a core and a shell layer coated on the surface of the core. The material of the core includes N-type inorganic nanoparticles, and the material of the shell layer includes montmorillonite nanosheets.

[0016] Optionally, in some embodiments of the present application, for every 1 mmol of cations in the cation source, 141-282 mg of the montmorillonite is correspondingly added; and / or,

[0017] The positively charged surface modifier includes a positively charged compound or a positively charged biopolymer. The positively charged biopolymer includes one or more of animal albumin and ovalbumin; the positively charged compound includes one or more of (2-mercaptoethyl) trimethyl ammonium chloride, octadecyl dimethyl benzyl ammonium chloride, (3-mercaptopropyl) ammonium chloride, 2-mercapto-3-trifluoromethyl pyridine, N-[3-(3-cyclopropyl-5-mercapto-4H-1,2,4-triazol-4-yl)phenyl] acetamide, 3-allyl-2-mercapto-3H-quinazolin-4-one, and N,N,N-trimethyl(11-mercapto decyl) ammonium chloride; and / or,

[0018] The temperature of the first reaction is 60-80 °C; and / or,

[0019] The time of the first reaction is 20-28 h; and / or,

[0020] Mix the montmorillonite nanosheets loaded with cations, the anion source, the positively charged surface modifier and the first polyol to form a first mixed system. The concentration of the positively charged surface modifier in the first mixed system is 0.02-0.1 mol / L; and / or,

[0021] The temperature of the second reaction is 180-250 °C; and / or,

[0022] The time of the second reaction is 1-3 h; and / or,

[0023] The molar ratio of the anion source to the first polyol is (10-50):1.

[0024] Optionally, in some embodiments of the present application, the step of treating the first solution to convert the montmorillonite loaded with cations into montmorillonite nanosheets loaded with cations includes:

[0025] Freezing and then thawing the first solution, and then performing ultrasonic treatment to obtain a second solution;

[0026] Providing a second polyol, mixing the second solution and the second polyol, and then performing microwave treatment to obtain montmorillonite nanosheets loaded with cations.

[0027] Optionally, in some embodiments of the present application, the time of the ultrasonic treatment is 0.5 - 1 h; and / or,

[0028] the time of the microwave treatment is 5 - 10 min; and / or,

[0029] the power of the microwave treatment is 500 - 600 W.

[0030] In a third aspect, the present application also provides an optoelectronic device, including an anode, an optical functional layer, an electronic functional layer, and a cathode, wherein the material of the electronic functional layer includes the composite material described above, or includes the composite material prepared by the preparation method described above.

[0031] Optionally, in some embodiments of the present application, the optical functional layer includes a light-emitting layer disposed between the electronic functional layer and the anode; the material of the light-emitting layer includes one or more of an organic light-emitting material and a quantum dot light-emitting material. The organic light-emitting material is selected from one or more of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridine iridium(III)], 4,4',4”-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridine iridium, poly[(9,9-dioctylfluorene-2,7-diyl)-alternating-(2,1,3-benzothiadiazole-4,7-diyl)], diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, thermally activated delayed material, a polymer containing B-N covalent bonding, a hybrid local charge transfer excited state material, and an exciplex luminescent material. The quantum dot light-emitting material is selected from at least one of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite-type semiconductor material; the material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds; the II-VI group compounds are selected from at least one of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds are selected from 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 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, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the I-III-VI compound is selected from at least one of CuInS2, CuInSe2 and AgInS2; 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 2+ Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ Yb 2+ Eu 2+ at least one of them, and X is a halogen anion selected from - Cl - Br - I n-2 NH 3+ or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation selected from 2+ Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ Yb 2+ Eu2+ at least one of them, X is a halogen anion, selected from Cl−, Br - , I - at least one of them; and / or,

[0032] The anode and the cathode are each independently selected from a doped metal oxide particle electrode, a composite electrode of a metal and a metal oxide, 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 composite electrode of a metal and a metal oxide 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, 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.

[0033] Fourthly, the present application also provides a display device, and the display device includes the optoelectronic device described above

[0034] The technical solution provided by the present application coats a layer of montmorillonite nanosheets on the surface of N-type inorganic nanoparticles, preventing the aggregation of N-type inorganic nanoparticles, isolating the N-type inorganic nanoparticles from the external environment, and improving the stability of the material. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 is a schematic flow chart of a preparation method of a composite material proposed in an embodiment of the present application;

[0037] Figure 2 is a schematic structural diagram of an optoelectronic device proposed in an embodiment of the present application;

[0038] Figure 3 is a comparison diagram of the PL spectra of the composite material solutions prepared in Material Example 1 and Material Comparative Examples 1 and 3 in Experimental Example 1;

[0039] Reference Signs:

[0040] 100 - optoelectronic device; 10 - anode; 20 - light - emitting layer; 30 - electron - functional layer; 40 - cathode; 50 - hole - transporting layer; 60 - hole - injecting layer. Detailed implementation manners

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation manners described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0042] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the drawings. In addition, in the description of the specification of the present application, the term "comprising" means "including but not limited to".

[0043] The various embodiments of the present 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 brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub - ranges and single 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 that range, such as 1, 2, 3, 4, 5, and 6, regardless of what the range is. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0044] In the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B may be singular or plural.

[0045] In the present application, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one item (individual) below" or similar expressions refer to any combination of these items, including any combination of single item (individual) or plural items (individuals). For example, "at least one item (individual) among a, b, or c", or, "at least one item (individual) among a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0046] The technical solution of this application is implemented as follows:

[0047] In a first aspect, the present application provides a composite material, which is a core-shell structure, including a core and a shell layer coated on the surface of the core, the material of the core includes N-type inorganic nanoparticles, and the material of the shell layer includes montmorillonite nanosheets.

[0048] The technical solution provided by the present application is that the composite material uses N-type inorganic nanoparticles as the core material and montmorillonite nanosheets as the external coating material. By coating a layer of montmorillonite nanosheets on the surface of the N-type inorganic nanoparticles, the agglomeration of the N-type inorganic nanoparticles is limited, and the N-type inorganic nanoparticles and the external environment are effectively isolated, so that the N-type inorganic nanoparticles are prevented from reacting with water and oxygen in the environment, and the material is also prevented from being affected by the thermal effect, thereby effectively improving the stability of the material; at the same time, the electron injection performance of the N-type inorganic nanoparticles can also be reduced, so that it can be suitable for occasions with low electron injection requirements. Specifically, when the composite material is used to prepare the electronic functional layer 30 of the optoelectronic device 100, on the one hand, because the composite material has good stability and is not easy to agglomerate at room temperature, it not only helps to improve the film-forming effect, but also can improve the forward aging phenomenon of the film layer under the action of the electric field and temperature, solves the problem of unstable storage performance of the device and the attenuation of the measured life, helps to extend the service life of the device, and improves its optoelectronic performance; on the other hand, it helps to reduce the electron injection of the electronic functional layer 30, which is conducive to the charge injection balance, thereby extending the service life of the device and improving its optoelectronic performance.

[0049] In some embodiments, the montmorillonite nanosheets and the N-type inorganic nanoparticles are coated via strong electrostatic interaction and adsorption. Specifically, the montmorillonite nanosheets have strong adsorption capacity due to their cavity structure, so that the surface of the sheet carries a negative charge, and the N-type inorganic nanoparticles are modified nanoparticles that have been modified and have a positive charge on their surface. Under the interaction of positive and negative charges, the montmorillonite nanosheets are adsorbed on the surface of the N-type inorganic nanoparticles to form a coating layer.

[0050] It is understood that the surface of the N-type inorganic nanoparticles is usually connected with a ligand, and the ligand is derived from one or more of an acid ligand, an amine ligand, and a thiol ligand. Specifically, the raw materials of the ligand include but are not limited to one or more of oleic acid, oleylamine, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid. The presence of the surface ligand will form a steric hindrance, which limits the coating of the N-type inorganic nanoparticles on the montmorillonite nanosheets. On the contrary, the montmorillonite nanosheets can be easily adsorbed on the surface of the N-type inorganic nanoparticles to form a coating layer.

[0051] Specifically, in some embodiments, the N-type inorganic nanoparticles are modified nanoparticles modified by a positively charged surface modifier. The positively charged surface modifier forms a positively charged group structure in a liquid environment, and the positively charged group structure is connected to the surface of the N-type inorganic nanoparticles, so that the surface of the N-type inorganic nanoparticles is positively charged. Further, the positively charged surface modifier includes a positively charged compound or a positively charged biopolymer. The positively charged biopolymer includes one or more of bovine serum albumin and ovalbumin. Among them, the bovine serum albumin can be one or more of bovine serum albumin (BSA) and mouse serum albumin; the positively charged compound includes one or more of (2-mercaptoethyl) trimethyl ammonium chloride, octadecyl dimethyl benzyl ammonium chloride, (3-mercaptopropyl) ammonium chloride, 2-mercapto-3-trifluoromethylpyridine, N-[3-(3-cyclopropyl-5-mercapto-4H-1,2,4-triazol-4-yl)phenyl]acetamide, 3-allyl-2-mercapto-3H-quinazolin-4-one, and N,N,N-trimethyl(11-mercapto decyl) ammonium chloride. When the positively charged surface modifier is a positively charged compound, for example, (3-mercaptopropyl) ammonium chloride, it dissociates to form (3-mercaptopropyl) ammonium ions, and the (3-mercaptopropyl) ammonium ions are bound to the surface of the N-type inorganic nanoparticles through sulfhydryl groups, so that the surface of the N-type inorganic nanoparticles is enriched with positively charged groups; when the positively charged surface modifier is a positively charged biopolymer, for example, BSA, it hydrolyzes to form positively charged amino acid residues, and the positively charged amino acid residues are bound to the surface of the N-type inorganic nanoparticles through active groups such as sulfhydryl groups and amino groups, so that the surface of the N-type inorganic nanoparticles is enriched with positively charged amino acid residues.

[0052] In some embodiments, in the composite material, the mass percentage content of the montmorillonite nanosheets is less than or equal to 60%; for example, it can be any value between 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50%, 55%, 60% and the values between any two of the above-listed values, as well as values less than 0.01% and greater than 0. In some other embodiments, in the composite material, the mass percentage content of the montmorillonite nanosheets is 20% to 50%.

[0053] In some embodiments, the montmorillonite nanosheets are two-dimensional sheet materials with an average thickness of 0.5 to 5 nm; for example, it can be 1 to 5 nm, 1.6 to 5 nm, 2 to 5 nm, 3 to 5 nm, 0.5 to 1.6 nm, 0.5 to 3 nm, 0.5 to 4 nm, etc.; specifically, it can be 0.5 nm, 1 nm, 1.6 nm, 1.7 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, and values between any two of the above-listed values. The thickness of the montmorillonite nanosheets is at the nanoscale and the size is extremely small, which can well coat the surface of N-type inorganic nanoparticles.

[0054] In some embodiments, the average particle size of the composite material is 1 to 10 nm; for example, it can be 1 to 3 nm, 1 to 6 nm, 1 to 8 nm, 7 to 10 nm, 4 to 10 nm, 3 to 8 nm, 2 to 9 nm, etc., and specifically, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, and values between any two of the above-listed values.

[0055] In some embodiments, the N-type inorganic nanoparticles may include, but are not limited to, one or more of N-type metal oxides or doped N-type metal oxides. The N-type metal oxides include one or more of ZnO, TiO2, SnO2, and ZrO2; the N-type metal oxides in the doped N-type metal oxides include one or more of ZnO, TiO2, SnO2, and ZrO2, and the doping elements include one or more of Al, Mg, Li, In, and Ga.

[0056] In a second aspect, the present application also proposes a preparation method of a composite material. Please refer to Figure 1 , and the preparation method includes the following steps:

[0057] S10, provide montmorillonite, a cation source, a solvent, an anion source, a positively charged surface modifier, and a first polyol;

[0058] S20, mix the montmorillonite, the cation source, and the solvent, and perform a first reaction to form a first solution, where the first solution contains montmorillonite loaded with cations;

[0059] S30, process the first solution to convert the montmorillonite loaded with cations into montmorillonite nanosheets loaded with cations;

[0060] S40. Mix the montmorillonite nanosheets loaded with cations, the anion source, the positively charged surface modifier, and the first polyol, and carry out a second reaction to obtain a composite material. The composite material includes a core and a shell layer coated on the surface of the core. The material of the core includes N-type inorganic nanoparticles, and the material of the shell layer includes montmorillonite nanosheets.

[0061] Among them, the cation source and the anion source are respectively used to provide cations and anions in the N-type inorganic nanoparticles. The cation source can be a metal salt, such as one or more of zinc salts, titanium salts, tin salts, and zirconium salts. Specifically, the metal salt can be a metal chloride, sulfate, nitrate, acetate, etc.; taking ZnO as an example of N-type inorganic nanoparticles, its corresponding cation source is a zinc salt, including but not limited to one or more of zinc acetate, zinc sulfate, zinc nitrate, and zinc chloride. The anion source can be water or an inorganic base. The inorganic base can be one of alkali metal oxides, alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal bicarbonates, such as one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium oxide, potassium oxide, calcium oxide, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, calcium bicarbonate, and barium hydroxide.

[0062] In some embodiments, the solvent includes water; in other embodiments, the first polyol can be a C2-C6 polyol, including but not limited to one or more of ethylene glycol, diethylene glycol, 2-propanol, 1,4-butanediol, and 1,6-hexanediol.

[0063] In some embodiments, the molar ratio of the anion source to the first polyol is (10-50):1, for example, it can be 10:1, 20:1, 30:1, 40:1, 50:1, and values between any two of the above-listed values. The mixed system of the anion source and the polyol can, on the one hand, promote the reaction of the cation source and the anion source to form N-type inorganic nanoparticles, and on the other hand, can regulate the reaction rate and inhibit the overgrowth of N-type inorganic nanoparticles.

[0064] In some embodiments, for every 1 mmol of cations in the cation source, 141-282 mg of the montmorillonite is correspondingly added; for example, the molar amount of cations in the cation source to the mass ratio of the montmorillonite (mmol:mg) can be 1:141, 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, 1:220, 1:240, 1:260, 1:282, and values between any two of the above-listed values.

[0065] In some embodiments, the positively charged surface modifier includes a positively charged compound or a positively charged biopolymer. The positively charged biopolymer includes one or more of bovine serum albumin and ovalbumin; the positively charged compound includes one or more of (2-mercaptoethyl) trimethyl ammonium chloride, octadecyl dimethyl benzyl ammonium chloride, (3-mercaptopropyl) ammonium chloride, 2-mercapto-3-trifluoromethylpyridine, N-[3-(3-cyclopropyl-5-mercapto-4H-1,2,4-triazol-4-yl)phenyl]acetamide, 3-allyl-2-mercapto-3H-quinazolin-4-one, and N,N,N-trimethyl(11-mercapto decyl) ammonium chloride.

[0066] In step S20, montmorillonite, a cation source, and a solvent are mixed. The cations in the cation source will undergo ion exchange with impurities such as sodium ions existing between the montmorillonite layers, forming montmorillonite with metal cations attached to the interlayers or surfaces.

[0067] In some embodiments, the first reaction is carried out at 60-80 °C; the first reaction temperature can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, and values between any two of the above-listed values. Controlling the temperature of the reaction system within this range helps to promote the ion exchange reaction.

[0068] In some embodiments, the time of the first reaction is 20-28 h (hours); for example, it can be 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, 26 h, 27 h, 28 h, and values between any two of the above-listed values.

[0069] In some embodiments, the addition amount of the positively charged surface modifier satisfies that the montmorillonite nanosheets loaded with cations, the anion source, the positively charged surface modifier, and the first polyol are mixed to form a first mixed system, and the concentration of the positively charged surface modifier in the first mixed system is 0.02-0.1 mol / L; the concentration can be 0.02 mol / L, 0.03 mol / L, 0.05 mol / L, 0.8 mol / L, 0.1 mol / L, and values between any two of the above-listed values.

[0070] In step S30, the ion-exchanged montmorillonite is exfoliated to form nanoscale, two-dimensional sheet-like montmorillonite nanosheets. In some embodiments, step S30 can be implemented according to the following steps:

[0071] S31, freeze the first solution and then thaw it, and then perform ultrasonic treatment to obtain a second solution;

[0072] S32. Provide a second polyol. After mixing the second solution and the second polyol, perform microwave treatment to obtain montmorillonite nanosheets loaded with cations.

[0073] In S31:

[0074] The freeze-thaw step may include: first freeze at -24°C to -18°C for 20 to 28 h, and then thaw at 15°C to 30°C for 20 to 28 h. The freeze-thaw step can be repeated multiple times. By repeatedly freezing and thawing, the interlayer force of montmorillonite is destroyed, prompting the montmorillonite to delaminate.

[0075] In some embodiments, the time of the ultrasonic treatment is 0.5 to 1 h; for example, it can be 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, and values between any two of the above-listed values.

[0076] In S32: The second polyol can be a C2 - C6 polyol, including but not limited to one or more of ethylene glycol, diethylene glycol, 2-propanediol, 1,4-butanediol, 1,6-hexanediol.

[0077] In some embodiments, the power of the microwave treatment is 500 to 600 W; for example, it can be 500 W, 510 W, 520 W, 530 W, 540 W, 550 W, 555 W, 558 W, 560 W, 562 W, 565 W, 570 W, 580 W, 590 W, 600 W, and values between any two of the above.

[0078] In some embodiments, the time of the microwave treatment is 5 to 10 min; for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, and values between any two of the above.

[0079] In step S40:

[0080] In some embodiments, the temperature of the second reaction is 180 to 250°C; for example, it can be 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, and values between any two of the above-listed values. Controlling the reaction temperature within this range prompts the cation source and the anion source to react to form N-type inorganic nanoparticles. In some other embodiments, before heating to the reaction temperature, it can also be vigorously stirred at room temperature in an inert gas environment for 60 min to prompt the full contact of the anion source, the positively charged surface modifier, and the montmorillonite nanosheets loaded with cations. Among them, the inert gas can be nitrogen, argon, etc.

[0081] In some embodiments, the time of the second reaction is 1 to 3 h; for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, and values between any two of the above-listed values.

[0082] In a third aspect, the present application also provides an optoelectronic device 100, and the optoelectronic device 100 may be an organic light-emitting diode (OLED), a quantum dot light-emitting diode (QLED), a solar cell, etc. For ease of description, hereinafter, the light-emitting diode will be taken as an example to specifically describe the structure of the optoelectronic device 100. Please refer to Figure 2 , the optoelectronic device 100 includes an anode 10, a light functional layer, an electron functional layer 30, and a cathode 40, and the material of the electron functional layer 30 includes the composite material described above, or includes the composite material prepared by the preparation method described above.

[0083] For the technical solution provided by the present application, the composite material uses an N-type inorganic nanoparticle as the core material and a montmorillonite nanosheet as the outer coating material. By coating a layer of montmorillonite nanosheets on the surface of the N-type inorganic nanoparticles, the agglomeration of the N-type inorganic nanoparticles is restricted, and the N-type inorganic nanoparticles are effectively isolated from the external environment, avoiding the reaction of the N-type inorganic nanoparticles with water and oxygen in the environment, and also avoiding the influence of the thermal effect on the material, thereby effectively improving the stability of the material; at the same time, the electron injection performance of the N-type inorganic nanoparticles can be reduced, making it applicable to occasions with low electron injection requirements. Specifically, when the composite material is applied to prepare the electron functional layer 30 of the optoelectronic device 100, on the one hand, due to the good stability of the composite material and its low tendency to agglomerate at room temperature, it not only helps to improve the film-forming effect, but also can improve the positive aging phenomenon of the film layer under the action of an electric field and temperature, solving the problems of unstable storage performance and attenuation of the measured life of the device, helping to extend the service life of the device and improve its optoelectronic performance; on the other hand, it helps to reduce the electron injection of the electron functional layer 30, is conducive to charge injection balance, and further extends the service life of the device and improves its optoelectronic performance.

[0084] In some embodiments, the anode 10 can be an anode 10 known in the art for optoelectronic device 100. For example, it can be selected from, but not limited to, doped metal oxide particle electrodes, composite electrodes of metal and metal oxide, graphene electrodes, carbon nanotube electrodes, metal electrodes or alloy electrodes. 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 composite electrode of metal and metal oxide 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, 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. Herein, " / " represents a stacked structure. For example, the composite electrode AZO / Ag / AZO represents an electrode with a three-layer stacked composite structure composed of an AZO layer, an Ag layer, and an AZO layer.

[0085] In some embodiments, the cathode 40 can be a cathode 40 known in the art for optoelectronic device 100. For example, it can be selected from, but not limited to, doped metal oxide particle electrodes, composite electrodes of metal and metal oxide, graphene electrodes, carbon nanotube electrodes, metal electrodes or alloy electrodes. 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 composite electrode of metal and metal oxide 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, 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. Herein, " / " represents a stacked structure. For example, the composite electrode AZO / Ag / AZO represents an electrode with a three-layer stacked composite structure composed of an AZO layer, an Ag layer, and an AZO layer.

[0086] The light functional layer may include a light absorption layer or a light-emitting layer 20. In some embodiments, the optoelectronic device 100 may be a light-emitting device, such as an OLED or a QLED, etc. Correspondingly, the light functional layer includes the light-emitting layer 20, and the light-emitting layer 20 is disposed between the electronic functional layer 30 and the anode 10. The material of the light-emitting layer 20 includes one or more of an organic light-emitting material and a quantum dot light-emitting material. The organic light-emitting material is selected from one or more of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridineiridium(III)], 4,4',4”-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridineiridium, poly[(9,9-dioctylfluorene-2,7-diyl)-alternating-(2,1,3-benzothiadiazole-4,7-diyl)], diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, thermally activated delayed material, a polymer containing a B-N covalent bond, a hybrid local charge transfer excited state material, and an exciplex light-emitting material; the quantum dot light-emitting material is selected from at least one of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite semiconductor material; the material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds; the II-VI group compounds are selected from at least one of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds are selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe;The group 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, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the group I-III-VI compound is selected from at least one of CuInS2, CuInSe2, and AgInS2;

[0087] 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.

[0088] 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, where 0 < x < 1.

[0089] The perovskite semiconductor material is selected from 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+ 、Co2+ 、 Fe 2+ 、 Ge 2+ 、 Yb 2+ 、 Eu 2+ and at least one of the following, X is a halogen anion selected from at least one of Cl-, Br - 、 I-; 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 NH 3+ or [NH3(CH2) n NH3]n 2+ , where n ≥ 2, 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 at least one of the following, X is a halogen anion selected from at least one of Cl-, Br - 、 I - and at least one of the following.

[0090] In some embodiments, the optoelectronic device 100 further includes a hole functional layer disposed between the electronic functional layer 30 and the anode 10; when the optoelectronic device 100 further includes a light-emitting layer 20, the hole functional layer is disposed between the light-emitting layer 20 and the anode 10. The hole functional layer includes one or both of a hole transport layer 50 and a hole injection layer 60. When the hole functional layer includes the hole transport layer 50 and the hole injection layer 60, the hole transport layer 50 and the hole injection layer 60 are stacked, and the hole injection layer 60 is located between the hole transport layer 50 and the anode 10. The hole functional layer can be prepared from hole functional materials known in the art for the optoelectronic device 100 and having hole transport performance or hole injection performance. Specifically, the material of the hole transport layer 50 may include, but is not limited to, poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4''-tris(carbazol-9-yl)triphenylamine (TCATA), 4,4'-bis(9-carbazolyl)biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS), Spiro-NPB, Spiro-TPD, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; the material of the hole injection layer 60 may include, but is not limited to, PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-polystyrenesulfonic acid), CuPc, TiOPc (phthalocyanine oxygen titanium), mMTDATA (CAS: 124729-98-2), 2-TNATA (4,4',4''-tris(2-naphthylphenylamino)triphenylamine), transition metal oxides, one or more of transition metal chalcogenides. Among them, the transition metal oxides include NiO x , MoO x , WO x , CrO x , CuO; one or more of the metal chalcogenides include MoS x , MoSe x , WS x , WSe x, one or more of CuS.

[0091] It can be understood that the optoelectronic device 100 can also be provided with some functional layers that are commonly used in optoelectronic devices 100 and are helpful for improving the performance of the optoelectronic device 100, such as an electron blocking layer, a hole blocking layer, etc.

[0092] It can be understood that the materials of the respective layers of the optoelectronic device 100 can be adjusted according to the actual requirements of the optoelectronic device 100.

[0093] It can be understood that the optoelectronic device 100 can be a normal-type device or an inverted-type device.

[0094] When there are multiple film layers provided between the anode 10 and the cathode 40, and the multiple film layers are selected from the light-emitting layer 20, the electron transport layer, the hole transport layer 50, and the hole injection layer 60, the film layer stacking order of the optoelectronic device 100 is the anode 10, the hole injection layer 60, the hole transport layer 50, the light-emitting layer 20, the electron transport layer, and the cathode 40; it can be understood that the optoelectronic device 100 can be a normal-type device or an inverted-type device. In some embodiments, the optoelectronic device 100 is a normal-type device. Correspondingly, the optoelectronic device 100 includes, from bottom to top in sequence, the anode 10, the hole injection layer 60, the hole transport layer 50, the light-emitting layer 20, the electron transport layer, and the cathode 40; in other embodiments, the optoelectronic device 100 is an inverted-type device. Correspondingly, the optoelectronic device 100 includes, from bottom to top in sequence, the cathode 40, the electron transport layer, the light-emitting layer 20, the hole transport layer 50, the hole injection layer 60, and the anode 10.

[0095] Based on the above embodiments of the optoelectronic device 100, the present application also proposes a preparation method of the optoelectronic device 100. The preparation method includes the following steps: preparing multiple film layers in sequence according to a preset film layer order to obtain the optoelectronic device 100; wherein, the multiple film layers include the anode 10, the cathode 40, and at least one functional layer provided between the anode 10 and the cathode 40. The at least one functional layer includes at least one of the light-emitting layer 20, the hole transport layer 50, the hole injection layer 60, and the electron transport layer. Among them, the preset film layer order refers to the order in which the optoelectronic device 100 is stacked from bottom to top.

[0096] In the optoelectronic device 100 provided by the present application, for the functional layer, the anode 10, and the cathode 40, conventional preparation methods can also be used for preparation. Specifically, the conventional preparation methods can be chemical methods or physical methods. Among them, the chemical methods include chemical vapor deposition method, sequential ionic layer adsorption and reaction method, anodic oxidation method, electrodeposition method, and coprecipitation method. The physical methods include physical coating method and solution method. Among them, the physical coating method includes: thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method, atomic layer deposition method, pulsed laser deposition method, etc.; the solution method can be spin coating method, printing method, inkjet printing method, blade coating method, printing method, dip coating method, immersion method, spraying method, roll coating method, casting method, slot die coating method, and bar coating method, etc.

[0097] In some embodiments, after the optoelectronic device 100 is prepared, it further includes the step of encapsulating the optoelectronic device 100. The encapsulation process can be carried out by using common machine encapsulation or manual encapsulation. Preferably, in the environment of the encapsulation process, both the oxygen content and the water content are lower than 0.1 ppm to ensure the stability of the optoelectronic device 100.

[0098] In addition, the present application also relates to a display device, and the display device includes the above-mentioned optoelectronic device 100. The display device can be any electronic product with a display function, and the electronic products include but are not limited to smartphones, tablet computers, laptop computers, digital cameras, digital video cameras, smart wearable devices, intelligent weighing electronic scales, in-vehicle displays, televisions, or e-book readers. Among them, the smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.

[0099] The technical solutions and technical effects of the present application will be described in detail below through specific examples and comparative examples. The following examples are only partial examples of the present application and do not specifically limit the present application.

[0100] Material Example 1

[0101] (1) According to the ratio of adding 211 mg of montmorillonite per 1 mmol of zinc acetate, montmorillonite was added to the aqueous solution of zinc acetate, and ion exchange was carried out at 60 - 80 °C for 24 h to obtain the first solution. Then, the first solution was transferred to a plastic beaker, frozen at -20 °C for 24 h, taken out, and thawed at 20 °C for 24 h to obtain the second solution. The completely thawed second solution was placed in an ultrasonic cleaner for ultrasonic treatment for 0.5 h. After centrifugation, the supernatant was added to diethylene glycol to form a solution with a total concentration (the sum of the concentration of montmorillonite and the concentration of zinc ions) of 0.03 mol / L, and microwave treatment was carried out for 5 min to obtain montmorillonite nanosheets loaded with zinc ions, where the average thickness of the montmorillonite nanosheets was about 5 nm.

[0102] (2) The montmorillonite nanosheets loaded with zinc ions were dissolved in a mixed solvent containing water - diethylene glycol (the molar ratio of water to diethylene glycol was 10:1), and bovine serum albumin (BSA) was added to form a mixed system. Among them, the addition amount of BSA was such that the concentration of BSA in the mixed system was 10 -2 mol / L. Under the conditions of room temperature and an argon atmosphere, the mixed system was vigorously stirred for 60 min, then heated to 180 °C for a hydrolysis reaction for 1 h to obtain a reaction solution. The reaction solution was washed with ethyl acetate and n - octane to precipitate, and a ZnO@montmorillonite composite material was obtained.

[0103] (3) The ZnO@montmorillonite composite material was dispersed in ethanol to obtain a composite material solution with a concentration of 30 mg / ml for standby.

[0104] Material Example 2

[0105] This material example is basically the same as Material Example 1, except that in this material example, in step (1), zinc acetate was changed to zinc acetylacetonate.

[0106] Material Example 3

[0107] This material example is basically the same as Material Example 1, except that in this material example, diethylene glycol was changed to 1,6 - hexanediol.

[0108] Material Example 4

[0109] This material example is basically the same as Material Example 1, except that in this material example, in step (1), the addition ratio of montmorillonite and zinc acetate was changed to: adding 282 mg of montmorillonite per 1 mmol of zinc acetate.

[0110] Material Example 5

[0111] This material example is basically the same as Material Example 1, except that in this material example, in step (1), the addition ratio of montmorillonite and zinc acetate is changed to: for every 1 mmol of zinc acetate, 141 mg of montmorillonite is added.

[0112] Material Example 6

[0113] This material example is basically the same as Material Example 1, except that in this material example, in step (1), the addition ratio of montmorillonite and zinc acetate is changed to: for every 1 mmol of zinc acetate, 320 mg of montmorillonite is added.

[0114] Material Example 7

[0115] This material example is basically the same as Material Example 1, except that in this material example, in step (2), bovine serum albumin (BSA) is changed to (2-mercaptoethyl) trimethyl ammonium chloride.

[0116] Material Comparative Example 1

[0117] This material comparative example is basically the same as Material Example 1, except that in this material comparative example, the composite material is ZnO nanoparticles.

[0118] Material Comparative Example 2

[0119] This material comparative example is basically the same as Material Example 1, except that in this material comparative example, montmorillonite nanosheets and ZnO nanoparticles are directly mixed. Correspondingly, in the preparation steps:

[0120] In step (1), the step of "adding montmorillonite to an aqueous solution of zinc acetate at a ratio of 211 mg of montmorillonite per 1 mmol of zinc acetate, and performing ion exchange at 60 - 80 °C for 24 h to obtain a first solution" is omitted, and montmorillonite is directly dispersed in water and then frozen as the first solution;

[0121] Step (2) is changed to: directly mixing the montmorillonite nanosheets and ZnO nanoparticles prepared in step (1) to form a composite material at a ratio of 211 mg of montmorillonite nanosheets per 1 mmol of ZnO nanoparticles.

[0122] Material Comparative Example 3

[0123] This material comparative example is basically the same as Material Example 1, except that in this material comparative example, bovine serum albumin (BSA) is not added in step (2).

[0124] Device Example 1

[0125] (1) Clean the ITO conductive glass with a cleaner to initially remove the stains on the surface. Subsequently, ultrasonically clean it in deionized water, isopropyl alcohol, acetone, and deionized water for 20 minutes respectively to remove the impurities on the surface. Finally, dry it with high-purity nitrogen to obtain the ITO anode;

[0126] (2) Spin-coat a chlorobenzene solution of TFB on the treated ITO anode to obtain a hole transport layer with a thickness of 30 nm;

[0127] (3) Spin-coat 40 nm thick blue light quantum dots CdZnSe / ZnS on the hole transport layer to obtain a light-emitting layer.

[0128] (4) Spin-coat the composite material solution prepared in Material Example 1 on the light-emitting layer to obtain an electron transport layer with a thickness of 40 nm.

[0129] (5) Vacuum-evaporate 100 nm thick Ag on the electron transport layer to obtain a cathode, and then encapsulate it to obtain an optoelectronic device.

[0130] Device Examples 2 to 7

[0131] The scheme of Device Example n is basically the same as that of Device Example 1, except that in Device Example n, in step (4), the spin-coated solution is changed to the composite material solution prepared in Material Example n, where n is from 2 to 7.

[0132] Device Comparative Examples 1 to 3

[0133] The scheme of this Device Comparative Example m is basically the same as that of Device Example 1, except that in this Device Comparative Example m, the spin-coated solution is changed to the composite material solution prepared in Material Comparative Example m, where m is from 1 to 3.

[0134] Experimental Example

[0135] (1) Take the composite material solutions prepared in Material Example 1, Material Comparative Example 1, and Material Comparative Example 3 above, and detect them with a fluorescence spectrometer (PL). The results are as Figure 3 shown.

[0136] As can be seen from the figure, the composite material solutions prepared in Material Comparative Example 1 and Material Comparative Example 3 both show peaks at around 550 nm, but the composite material solution prepared in Material Example 1 does not have a peak here; this may be because in Material Example 1, the montmorillonite nanosheets form a coating layer on the surface of the ZnO nanoparticles, promoting the disappearance of the defect luminescence at 550 nm. In the solution of Material Comparative Example 1, there are only individual ZnO nanoparticles, so the defect luminescence peak still exists. In the solution of Material Comparative Example 3, since no surface modifier is added, the ZnO nanoparticles cannot be surface-charged, resulting in the inability to adsorb between them and the montmorillonite nanosheets, and the montmorillonite coating layer cannot be formed. Therefore, the defect luminescence still exists.

[0137] (2) Perform EQE and T95 tests on the devices prepared in the above Device Examples 1-7 and Device Comparative Examples 1-3. The detection method refers to the conventional methods in the art, and the results are recorded in Table 1. Among them:

[0138] (1) The detection method for external quantum efficiency (EQE) is: the ratio of the number of electron-hole pairs injected into the quantum dots to the number of emitted photons, with the unit of %, which is an important parameter to measure the quality of electro-optical devices and can be obtained by measuring with an EQE optical test instrument. The specific calculation formula is as follows:

[0139]

[0140] Among them, ηe is the optical output coupling efficiency, ηγ is the ratio of the number of recombined carriers to the number of injected carriers, x is the ratio of the number of excitons generating photons to the total number of excitons, KR is the radiation process rate, and KNR is the non-radiation process rate.

[0141] Test conditions: Conducted at room temperature with an air humidity of 30-60%.

[0142] (2) The test method for lifetime T95@1000nit is:

[0143] The time required for the device to reduce the brightness to a certain proportion of the maximum brightness under constant current or voltage drive. The time when the brightness drops to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the test cycle, the device lifetime test is usually carried out by accelerating the device aging at high brightness and obtaining the lifetime at high brightness through fitting with an extended exponential decay brightness decay fitting formula. For example, the lifetime at 1000nit is denoted as T95@1000nit. The specific calculation formula is as follows:

[0144]

[0145] Among them, T95 L is the lifetime at low brightness, T95 H is the measured lifetime at high brightness, L H is the device accelerated to the maximum brightness, L L is 1000nit, A is the acceleration factor, and in this experiment, the A value is obtained as 1.7 by measuring the lifetimes of several groups of QLED devices at the rated brightness.

[0146] Table 1

[0147]

[0148]

[0149] Please refer to Table 1, and it can be seen that:

[0150] Device Examples 1 to 7 have significantly higher EQE and T95 than Device Comparative Examples 1 to 3, indicating that using the ZnO@montmorillonite composite material to fabricate the electron transport layer in this application helps improve the light-emitting efficiency and lifespan of the device. This may be because the montmorillonite nanosheets are coated outside ZnO, isolating the chemical reaction and heat exchange between ZnO and environmental water and oxygen, thereby enhancing the stability of ZnO as an electron transport layer material and showing a high measured lifespan in QLED devices. On the other hand, after montmorillonite coats ZnO, the electron injection of the electron transport layer is reduced, which is beneficial to the charge injection balance, thus increasing the quantum efficiency.

[0151] In addition, compared with Device Comparative Example 1, the EQE and T95 of Device Comparative Examples 2 and 3 not only did not increase but instead decreased significantly. The reason may be that in these two comparative examples, the montmorillonite nanosheets did not form a coating layer on the surface of ZnO but were free and dispersed in the film layer. Therefore, not only did they fail to protect ZnO and reduce electron injection, but instead, due to the incorporation of free montmorillonite, the carrier transport performance of the film layer was interfered with, resulting in a decrease in its lifespan and light-emitting efficiency.

[0152] The above has introduced in detail the composite material provided in the embodiments of this application, its preparation method, optoelectronic device, and display device. Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application. At the same time, for those skilled in the art, based on the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A composite material, characterized in that, It includes a core and a shell layer coated on the surface of the core. The material of the core includes N-type inorganic nanoparticles, and the material of the shell layer includes montmorillonite nanosheets.

2. The composite material according to claim 1, characterized in that, In the composite material, the mass percentage content of the montmorillonite nanosheets is less than or equal to 60%.

3. The composite material according to claim 1, characterized in that, The average thickness of the montmorillonite nanosheets is 0.5 - 5 nm.

4. The composite material according to claim 1, characterized in that, The average particle size of the composite material is 1 - 10 nm.

5. The composite material according to claim 1, characterized in that, The N-type inorganic nanoparticles include one or more of N-type metal oxides or doped N-type metal oxides. The N-type metal oxides include one or more of ZnO, TiO2, SnO2, and ZrO2; the N-type metal oxides in the doped N-type metal oxides include one or more of ZnO, TiO2, SnO2, and ZrO2, and the doping elements include one or more of Al, Mg, Li, In, and Ga.

6. A method for preparing a composite material, characterized in that, It includes the following steps: Providing montmorillonite, a cation source, a solvent, an anion source, a positively charged surface modifier, and a first polyol; Mixing the montmorillonite, the cation source, and the solvent, and performing a first reaction to form a first solution, the first solution containing montmorillonite loaded with cations; Processing the first solution to convert the montmorillonite loaded with cations into montmorillonite nanosheets loaded with cations; Mixing the montmorillonite nanosheets loaded with cations, the anion source, the positively charged surface modifier, and the first polyol, and performing a second reaction to obtain a composite material, the composite material including a core and a shell layer coated on the surface of the core. The material of the core includes N-type inorganic nanoparticles, and the material of the shell layer includes montmorillonite nanosheets.

7. The preparation method according to claim 6, characterized in that, For every 1 mmol of cations in the cation source, 141 - 282 mg of the montmorillonite is correspondingly added; and / or, The positively charged surface modifier includes a positively charged compound or a positively charged biopolymer. The positively charged biopolymer includes one or more of bovine serum albumin and ovalbumin; the positively charged compound includes one or more of (2-mercaptoethyl)trimethylammonium chloride, octadecyldimethylbenzylammonium chloride, (3-mercaptopropyl)ammonium chloride, 2-mercapto-3-trifluoromethylpyridine, N-[3-(3-cyclopropyl-5-mercapto-4H-1,2,4-triazol-4-yl)phenyl]acetamide, 3-allyl-2-mercapto-3H-quinazolin-4-one, and N,N,N-trimethyl(11-mercapto-decyl)ammonium chloride; and / or, The temperature of the first reaction is 60 - 80 °C; and / or, The time of the first reaction is 20 - 28 h; and / or, The montmorillonite nanosheets loaded with cations, the anion source, the positively charged surface modifier, and the first polyol are mixed to form a first mixed system, and the concentration of the positively charged surface modifier in the first mixed system is 0.02 - 0.1 mol / L; and / or, The temperature of the second reaction is 180 - 250 °C; and / or, The time of the second reaction is 1 - 3 h; and / or, The molar ratio of the anion source to the first polyol is (10 - 50):

1.

8. The preparation method according to claim 6, characterized in that, The step of treating the first solution to convert the montmorillonite loaded with cations into montmorillonite nanosheets loaded with cations includes: Freezing and then thawing the first solution, and then performing ultrasonic treatment to obtain a second solution; Providing a second polyol, mixing the second solution and the second polyol, and then performing microwave treatment to obtain montmorillonite nanosheets loaded with cations.

9. The preparation method according to claim 8, characterized in that, The time of the ultrasonic treatment is 0.5 - 1 h; and / or, The time of the microwave treatment is 5 - 10 min; and / or, The power of the microwave treatment is 500 - 600 W.

10. An optoelectronic device, characterized in that, It includes an anode, a light functional layer, an electron functional layer, and a cathode. The material of the electron functional layer includes the composite material according to any one of claims 1 to 5, or includes the composite material prepared by the preparation method according to any one of claims 6 to 9.

11. The optoelectronic device according to claim 10, characterized in that, The light functional layer includes a light-emitting layer, and the light-emitting layer is disposed between the electronic functional layer and the anode; the material of the light-emitting layer includes one or more of an organic light-emitting material and a quantum dot light-emitting material. The organic light-emitting material is selected from one or more of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridineiridium(III)], 4,4',4''-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridineiridium, poly[(9,9-dioctylfluorene-2,7-diyl)-alternating-(2,1,3-benzothiadiazole-4,7-diyl)], diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, thermally activated delayed material, a polymer containing a B-N covalent bond, a hybrid local charge transfer excited state material, and an exciplex light-emitting material. The quantum dot light-emitting material is selected from at least one of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite-type semiconductor material; the material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds; the II-VI group compounds are selected from at least one of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds are selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe;The group 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, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the group I-III-VI compound is selected from at least one of CuInS2, CuInSe2 and AgInS2; 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 2+ Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ Yb 2+ Eu 2+ and at least one of X is a halogen anion selected from Cl-, Br - I - ; 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 NH 3+ 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, X is a halogen anion, selected from Cl - , Br - , I - at least one of; and / or, The anode and the cathode are each independently selected from a doped metal oxide particle electrode, a composite electrode of a metal and a metal oxide, 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 composite electrode of a metal and a metal oxide 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, 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.

12. A display device, characterized in that, The display device includes the optoelectronic device according to claim 10 or 11.

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