Composite material, film, composite film, and light emitting device

Abstract

The invention discloses a composite material, a preparation method thereof and a light-emitting device. The composite material comprises quantum dots and magnetic ionic liquid. According to the composite material disclosed by the invention, the quantum dots are not easy to agglomerate.

Description

Technical Field

[0001] This application relates to the field of display technologies, and in particular, to a composite material, a thin film, a composite thin film, and a light-emitting device. Background Art

[0002] Quantum dots, as semiconductor nanoparticles with unique optical and electrical properties, have attracted much attention in many fields. Especially in electroluminescence (EL) applications such as displays and lighting, quantum dots have advantages such as high brightness, wide color gamut, and long lifespan.

[0003] However, the existing quantum dots have poor stability and need to be further improved. Summary of the Invention

[0004] In view of this, this application provides a composite material, aiming to improve the problem of poor stability of existing quantum dots.

[0005] An embodiment of this application is implemented as follows. A composite material includes quantum dots and magnetic ionic liquid.

[0006] Optionally, in some embodiments, in the composite material, the mass ratio of the magnetic ionic liquid to the quantum dots is (1 - 5):15;

[0007] And / or, the magnetic ionic liquid includes one or more of a pure organic magnetic ionic liquid and a magnetic ionic liquid containing a metal element.

[0008] Optionally, in some embodiments, the pure organic magnetic ionic liquid includes one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, the compound shown in formula (I), and the compound shown in formula (II);

[0009]

[0010] Wherein, R1 and R2 are each independently selected from one or more of H, substituted or unsubstituted C1 - C20 alkyl groups, and the substituents of the substituted ones are selected from deuterium, amino group, halogen, hydroxyl group, carboxyl group, nitro group, aldehyde group, cyano group, C1 - C6 alkyl groups, C1 - C6 alkoxy groups, C1 - C6 alkoxycarbonyl groups, and C1 - C6 alkyl acyloxy groups;

[0011] And / or, the magnetic ionic liquid containing a metal element includes one or more of a magnetic ionic liquid containing a transition metal element and a magnetic ionic liquid containing a lanthanide metal element.

[0012] Optionally, in some embodiments, R1 and R2 are each independently selected from one or more of H, C1 - C10 straight-chain alkyl groups;

[0013] And / or, the chemical formula of the metal element-containing magnetic ionic liquid is A m M n ;

[0014] wherein, m and n are natural numbers;

[0015] A is selected from one or more of alkyl-substituted imidazole cations, alkyl-substituted pyrrole cations, and alkyl-substituted pyridine cations;

[0016] M is selected from one or more of iron tetrahalide anions, transition metal tris(hexafluoroacetylacetonate) anions, and lanthanide metal tris(hexafluoroacetylacetonate) anions.

[0017] Optionally, in some embodiments, the alkyl-substituted imidazole cations include one or more of 1-butyl-3-methylimidazole cations, 1-ethyl-3-methylimidazole cations, and 1-methyl-3-alkylimidazole cations;

[0018] And / or, the alkyl-substituted pyrrole cations include 1-butyl-1-methylpyrrole cations;

[0019] And / or, the alkyl-substituted pyridine cations include 1-butylpyridine cations;

[0020] And / or, the iron tetrahalide anions include [FeCl4] - , [FeBr4] - , [FeCl4] - , [FeF4] - , [FeCl3Br] - one or more of;

[0021] And / or, the transition metal tris(hexafluoroacetylacetonate) anions include one or more of cobalt tris(hexafluoroacetylacetonate) anions, manganese tris(hexafluoroacetylacetonate) anions, and nickel tris(hexafluoroacetylacetonate) anions;

[0022] And / or, the lanthanide metal tris(hexafluoroacetylacetonate) anions include one or more of dysprosium tris(hexafluoroacetylacetonate) anions, gadolinium tris(hexafluoroacetylacetonate) anions, and neodymium tris(hexafluoroacetylacetonate) anions.

[0023] Optionally, in some embodiments, the magnetic ionic liquid containing a transition metal element includes, but is not limited to, one or more of 1-butyl-3-methylimidazolium iron(III) chloride, 1-butyl-1-methylpyrrolidinium iron(III) chloride, 1-butylpyridinium iron(III) chloride, 1-ethyl-3-methylimidazolium iron(III) chloride, 1-methyl-3-alkylimidazolium iron(III) chloride, 1-butyl-3-methylimidazolium bromoiron(III) chloride, 1-butyl-3-methylimidazolium cobalt(III) tris(hexafluoroacetylacetonate), 1-butyl-3-methylimidazolium manganese(III) tris(hexafluoroacetylacetonate), 1-butyl-3-methylimidazolium nickel(II) tris(hexafluoroacetylacetonate);

[0024] And / or, the magnetic ionic liquid containing a lanthanide metal element includes one or more of 1-hexyl-methylimidazolium dysprosium(III) thiocyanate, 1-methyl-3-alkyldiimidazolium dysprosium(III) thiocyanate, 1-ethyl-3-methylimidazolium dysprosium(III) chloride, 1-butyl-3-methylimidazolium dysprosium(III) tris(hexafluoroacetylacetonate), 1-butyl-3-methylimidazolium gadolinium(III) tris(hexafluoroacetylacetonate), 1-butyl-3-methylimidazolium neodymium(III) tris(hexafluoroacetylacetonate).

[0025] Optionally, in some embodiments, the quantum dots include one or more of single-structure quantum dots, core-shell structure quantum dots, perovskite semiconductor materials, silicon quantum dots, and germanium quantum dots. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots include one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds include one or more 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 include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The III-V group compounds include 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, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb. The I-III-VI group compounds include one or more of CuInS2, CuInSe2, and AgInS2. The perovskite semiconductor materials include doped or undoped inorganic perovskite semiconductors or organic-inorganic hybrid perovskite semiconductors. The structural general formula of the inorganic perovskite semiconductors is AMX3, where A is Cs + ions, M is a divalent metal cation, including Pb 2+ , Sn 2+ , Cu2+ 、Ni 2+ 、Cd 2+ 、Cr 2+ 、Mn 2+ 、Co 2+ 、Fe 2+ 、Ge 2 + 、Yb 2+ 、Eu 2+ One or more of the following, X is a halogen anion, including Cl - 、Br - 、I - One or more of the following, the structural general 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 the following, X is a halogen anion, including Cl - 、Br - 、I - One or more of the following;

[0026] And / or, the average particle size range of the quantum dots is 8-15 nm;

[0027] And / or, the surface of the quantum dots is connected with ligands, and the ligands include substituted or unsubstituted C6-C 24 fatty acids, substituted or unsubstituted C6-C 24 fatty amines, substituted or unsubstituted C6-C 24 aliphatic thiols, substituted or unsubstituted C6-C 24 aliphatic thioethers, substituted or unsubstituted C6-C 24 aliphatic phosphines, substituted or unsubstituted C6-C 24 aliphatic phosphine oxides, substituted or unsubstituted C6-C 20 aliphatic phosphoric acids, substituted or unsubstituted C8-C 24 aliphatic phosphates, substituted or unsubstituted C6-C24 at least one of aliphatic phosphorous acid and substituted or unsubstituted C6-C 24 at least one of aliphatic phosphite ester;

[0028] Optionally, the substituted or unsubstituted C6-C 24 fatty acids include at least one of capric acid, undecylenic acid, myristic acid, oleic acid, linoleic acid, stearic acid;

[0029] Optionally, the substituted or unsubstituted C6-C 24 aliphatic thiols include at least one of octanethiol, dodecyl mercaptan, octadecyl mercaptan;

[0030] Optionally, the substituted or unsubstituted C6-C 24 fatty amines include at least one of oleylamine, octadecylamine, octylamine, dioctylamine, trioctylamine;

[0031] Optionally, the substituted or unsubstituted C6-C 24 aliphatic phosphines include trioctylphosphine;

[0032] Optionally, the substituted or unsubstituted C6-C 24 aliphatic phosphine oxides include trioctylphosphine oxide.

[0033] Correspondingly, the embodiment of the present application further provides a thin film, including the composite material.

[0034] Correspondingly, the embodiment of the present application further provides a composite thin film, including a quantum dot layer and an ionic liquid layer disposed on at least one surface of the quantum dot layer, wherein the material of the quantum dot layer includes quantum dots, and the material of the ionic liquid layer includes the magnetic ionic liquid.

[0035] Correspondingly, the embodiment of the present application further provides a light-emitting device, which includes a first electrode, a light-emitting layer, and a second electrode stacked in sequence, wherein the light-emitting layer includes the composite material, or the light-emitting layer is the thin film, or the light-emitting layer is the composite thin film.

[0036] Optionally, in some embodiments, the light-emitting device further includes one or more of a first charge carrier functional layer and a second charge carrier functional layer, the first charge carrier functional layer is disposed between the first electrode and the light-emitting layer, and the second charge carrier functional layer is disposed between the light-emitting layer and the second electrode; the first charge carrier functional layer is a hole functional layer, and the second charge carrier functional layer is an electron functional layer; or the second charge carrier functional layer is a hole functional layer, and the first charge carrier functional layer is an electron functional layer;

[0037] Optionally, each of the first electrode and the second electrode independently includes one or more of a metal, a carbon material, and a metal oxide; the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes one or more of graphite, carbon nanotubes, graphene, and carbon fiber; the metal oxide includes a metal oxide electrode or a composite electrode having a metal disposed between doped or undoped transparent metal oxides, the material of the metal oxide electrode includes one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3, and AMO, and 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, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2;

[0038] Optionally, the material of the hole functional layer includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent material, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 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(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS derivatives doped with s-MoO3, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine, spiro-NPB, nanocrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfides, metal selenides and metal nitrides, the metal oxides in the second doped metal oxide particles and the metal oxides in the second undoped metal oxide particles each independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, V2O5, the doping elements in the second doped metal oxide particles include one or more of Mo, W, Ni, Cr, Cu, V, the metal sulfides include one or more of CuS, MoS3, WS3, the metal selenides include one or more of MoSe3, WSe3, and the metal nitrides include p-type gallium nitride;

[0039] Optionally, the material of the electronic functional layer includes one or more of first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The material of the first undoped metal oxide particles includes one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the first doped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the first doped metal oxide particles include one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS.

[0040] The composite material described in this application includes the quantum dots and the magnetic ionic liquid, which can prevent the quantum dots from agglomerating. Description of the Drawings

[0041] To more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0042] Figure 1 It is a schematic structural diagram of a composite film provided by an embodiment of this application;

[0043] Figure 2 It is a schematic structural diagram of another composite film provided by an embodiment of this application;

[0044] Figure 3 It is a schematic structural diagram of a light-emitting device provided by an embodiment of this application;

[0045] Figure 4 It is a schematic structural diagram of another light-emitting device provided by an embodiment of this application;

[0046] Figure 5 It is a schematic structural diagram of yet another light-emitting device provided by an embodiment of this application.

[0047] Reference Signs

[0048] Light-emitting device 100; anode 10; light-emitting layer 20; cathode 30; hole transport layer 40; electron transport layer 50; hole injection layer 60; composite film 1; quantum dot layer 11; ionic liquid layer 12. Detailed implementation manners

[0049] 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application. In addition, it should be understood that the specific implementation manners described herein are only for explaining and understanding the present application, and are not used to limit the present application.

[0050] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "including" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0051] In the present application, "and / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural.

[0052] In the present application, "at least one" means one or more, and "multiple" means two or more. "At least one kind", "at least one item (piece) below" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one item (piece) of a, b, or c", or, "at least one item (piece) of a, b, and c" can both represent: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.

[0053] In the present application, when forming another layer "on" a certain layer, the so-called "on" is a broad concept, which can mean that the formed another layer is adjacent to a certain layer, or there are other spacer structure layers between another layer and a certain layer. For example, when forming a second electrode "on" a first carrier functional layer, the so-called "on" can mean that the formed second electrode is adjacent to the first carrier functional layer, or there are other spacer structure layers between the second electrode and the first carrier functional layer, such as a light-emitting layer.

[0054] 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 individual 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 individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0055] QLED has excellent characteristics such as narrow FWHM (Full Width at Half Maximum), color tunability, and solution processability, making it a candidate for the next-generation display technology. Therefore, different researchers have studied QLED from different perspectives, gradually improving the performance of the device.

[0056] Currently, the surface effect of solution-processed quantum dots results in a large number of surface defects, which are easily affected by water, oxygen, and radiation, affecting the photostability of the quantum dots and prone to fluorescence quenching. In particular, blue quantum dots with a smaller specific surface area have an even smaller specific surface area, resulting in more surface defects, making the lifespan of light-emitting devices prepared from blue quantum dots much lower than that of red and green QLEDs. In addition, when preparing quantum dot films using quantum dot solutions, the disordered film formation of quantum dots will form interface defects, reducing the device performance.

[0057] The technical solution of the present application is as follows:

[0058] An embodiment of the present application provides a composite material, comprising quantum dots and magnetic ionic liquid.

[0059] Magnetic ionic liquid refers to a salt that is liquid at room temperature or near room temperature and is completely composed of cations and anions and has magnetism, also known as a low-temperature molten salt.

[0060] The anion in the magnetic ionic liquid can undergo a Lewis acid-base reaction with the metal cations on the surface of the quantum dots to form coordination, thereby enabling the magnetic ionic liquid to be coordinately connected to the quantum dots. In this way, both the magnetic ionic liquid and the quantum dots can be connected together, and the cation defects on the surface of the quantum dots can be passivated.

[0061] The composite material described in this application includes the quantum dots, the coordination linker, and the magnetic ionic liquid on the quantum dots. On the one hand, when using the composite material to prepare a thin film, the quantum dots in the film layer can be tightly bonded, and the quantum dots are not prone to agglomeration, which is beneficial to making the prepared thin film uniform, dense, smooth, and have strong chemical stability, effectively improving the film-forming morphology of the thin film and reducing the surface defects of the thin film. Thus, when the thin film is a thin film of a light-emitting device, the leakage current can be effectively suppressed, and the problem of serious device lifetime decay can be improved. On the other hand, the magnetic ionic liquid has high conductivity, which can reduce the transport barrier of carriers inside the device to a certain extent, improve the utilization rate of carriers, and thus improve the light-emitting performance of the device. On the other hand, the magnetic ionic liquid has magnetism and can generate a certain response to an external magnetic field under the action of its magnetic center. Thus, when using the composite material to prepare a thin film, the property that the magnetic ionic liquid has magnetism can be utilized to apply a magnetic field and adjust the sorting of the quantum dots by using the external magnetic field to obtain a more orderly arranged quantum dot film.

[0062] In some embodiments, in the composite material, the mass ratio of the magnetic ionic liquid to the quantum dots is (1-5):15. For example, 1:15, 1.5:15, 2:15, 2.5:15, 3:15, 3.5:15, 4:15, 4.5:15, 5:15, etc. Within this ratio range, the agglomeration of quantum dots can be effectively avoided, the composite material can have good conductivity, and the composite material can also have good film-forming properties.

[0063] In some embodiments, the magnetic ionic liquid includes, but is not limited to, one or more of pure organic magnetic ionic liquids and magnetic ionic liquids containing metal elements.

[0064] It can be understood that the pure organic magnetic ionic liquid is a magnetic ionic liquid that does not contain metal in both the cation and the anion, and its magnetic source is mainly the radical structure it contains.

[0065] In some embodiments, the pure organic magnetic ionic liquid includes, but is not limited to, one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, the compound shown in formula (I), and the compound shown in formula (II);

[0066]

[0067]

[0068] Among them, R1 and R2 are each independently selected from one or more of H, substituted or unsubstituted C1-C20 alkyl groups, and the substituents of the substituted ones are selected from deuterium, amino group, halogen, hydroxyl group, carboxyl group, nitro group, aldehyde group, cyano group, C1-C6 alkyl group, C1-C6 alkoxy group, C1-C6 alkoxycarbonyl group, C1-C6 alkylacyloxy group.

[0069] Further, in some embodiments, R1 and R2 are each independently selected from one or more of H, straight-chain C1-C10 alkyl groups.

[0070] Further, in some embodiments, R1 and R2 are each independently selected from one or more of H, straight-chain C1-C6 alkyl groups.

[0071] Further, in some embodiments, R1 and R2 are each independently selected from H, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and the like.

[0072] As an example, the compound represented by the formula (I) can be any one of the following structural formulas:

[0073]

[0074] As an example, the compound represented by the formula (I) can be any one of the following structural formulas:

[0075]

[0076]

[0077] The metal element-containing magnetic ionic liquid refers to an ionic liquid with a metal complex as the anion, and its magnetism mainly comes from the metal ions contained in the anion, such as Fe ions, Co ions, Ni ions, Mn ions, Dy ions, Gd ions, Nd ions, etc.

[0078] The chemical formula of the metal element-containing magnetic ionic liquid is A m M n ;

[0079] Among them, m and n are natural numbers;

[0080] A is selected from one or more of alkyl-substituted imidazole cations (mim), alkyl-substituted pyrrole cations (py), and alkyl-substituted pyridine cations (mp);

[0081] M is selected from tetrahaloferrate anions ([FeX4] -) one or more of transition metal tris(hexafluoroacetylacetonate) anions and lanthanide metal tris(hexafluoroacetylacetonate) anions. Among them, tris(hexafluoroacetylacetonate) can be abbreviated as hfacac.

[0082] In some embodiments, the alkyl-substituted imidazolium cations may include, but are not limited to, one or more of 1-butyl-3-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, and 1-methyl-3-alkylimidazolium cation.

[0083] In some embodiments, the alkyl-substituted pyrrolidinium cations may include, but are not limited to, 1-butyl-1-methylpyrrolidinium cation.

[0084] In some embodiments, the alkyl-substituted pyridinium cations may include, but are not limited to, 1-butylpyridinium cation.

[0085] In some embodiments, the iron tetrahalide anions may include, but are not limited to, [FeCl4] - , [FeBr4] - , [FeCl4] - , [FeF4] - , [FeCl3Br] - or one or more of them.

[0086] In some embodiments, the transition metal tris(hexafluoroacetylacetonate) anions include, but are not limited to, one or more of cobalt(III) tris(hexafluoroacetylacetonate) anion, manganese(III) tris(hexafluoroacetylacetonate) anion, and nickel(III) tris(hexafluoroacetylacetonate) anion.

[0087] In some embodiments, the lanthanide metal tris(hexafluoroacetylacetonate) anions include, but are not limited to, one or more of dysprosium tris(hexafluoroacetylacetonate) anion, gadolinium tris(hexafluoroacetylacetonate) anion, and neodymium tris(hexafluoroacetylacetonate) anion.

[0088] In some embodiments, the metal element-containing magnetic ionic liquids include, but are not limited to, one or more of transition metal element-containing magnetic ionic liquids and lanthanide metal element-containing magnetic ionic liquids.

[0089] As an example, in some embodiments, the transition metal element-containing magnetic ionic liquids include, but are not limited to, 1-butyl-3-methylimidazolium tetrachloroferrate ([bmim][FeCl4]), 1-butyl-1-methylpyrrolidinium tetrachloroferrate ([nbmp][FeCl4]), 1-butylpyridinium tetrachloroferrate ([bpy][FeCl4]), 1-ethyl-3-methylimidazolium tetrachloroferrate ([emim][FeCl4]), 1-methyl-3-alkylimidazolium tetrachloroferrate ([Cn’ mim][FeCl4], where n' = 2, 4, 6, 8), 1-butyl-3-methylimidazolium bromochloride ferrate ([C4mim][FeCl3Br]), 1-butyl-3-methylimidazolium tris(hexafluoroacetylacetonato) transition metal salt (III) ([C4mim][M'(hfacac)3], M' includes but is not limited to Co, Mn or Ni), or one or more of them.

[0090] As an example, in some embodiments, the lanthanide metal element-containing magnetic ionic liquid includes but is not limited to 1-hexyl-methylimidazolium dysprosium thiocyanate ([C6min] 5-x [Dy(SCN) 8-x (H2O) x , [Hmim] 5-x [Dy(SCN) 8-x (H2O) x , where 0 ≤ x ≤ 2), 1-methyl-3-alkyldiimidazolium dysprosium thiocyanate ([C n ”(mim)2]2[Dy(SCN)7], n” is 2, 4, 6 or 8), 1-ethyl-3-methylimidazolium dysprosium tetrachloride ([emim][DyCl4]), 1-butyl-3-methylimidazolium tris(hexafluoroacetylacetonato) lanthanide metal salt (IV) ([C4mim][M”(hfacac)4], M” includes but is not limited to Dy, Gd or Nd), or one or more of them.

[0091] It can be understood that when the magnetic ionic liquid contains N-H or halogen atoms, the N-H or halogen atoms can form hydrogen bonds with the anions on the surface of the quantum dots, thereby enhancing the binding strength between the magnetic ionic liquid and the quantum dots.

[0092] The quantum dots may include, but are not limited to, one or more of single-structure quantum dots, core-shell structure quantum dots, perovskite semiconductor materials, silicon quantum dots, and germanium quantum dots. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots may each include, but are not limited to, one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds may include, but are not limited to, one or more 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 may include, but are not limited to, one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The III-V group compounds may include, but are not limited to, 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, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb. The I-III-VI group compounds may include, but are not limited to, one or more of CuInS2, CuInSe2, and AgInS2. The perovskite semiconductor materials may include, but are not limited to, doped or undoped inorganic perovskite semiconductor materials, or organic-inorganic hybrid perovskite semiconductor materials. The structural general formula of the inorganic perovskite semiconductor is AMX3, where A is Cs + ions, and M is a divalent metal cation, including Pb2 + , 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 the following, X is a halogen 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 the following, X is a halogen anion, including Cl - , Br - , I - One or more of the following.

[0093] In some embodiments, the average particle size range of the quantum dots is 8 - 15 nm.

[0094] In some embodiments, the surface of the quantum dots is connected with ligands, and the ligands include substituted or unsubstituted C6 - C 24 fatty acids, substituted or unsubstituted C6 - C 24 fatty amines, substituted or unsubstituted C6 - C 24 aliphatic thiols, substituted or unsubstituted C6 - C 24 aliphatic thioethers, substituted or unsubstituted C6 - C 24 aliphatic phosphines, substituted or unsubstituted C6 - C 24 aliphatic phosphine oxides, substituted or unsubstituted C8 - C 20aliphatic phosphoric acid, substituted or unsubstituted C6-C 24 aliphatic phosphate ester, substituted or unsubstituted C6-C 24 aliphatic phosphorous acid, and substituted or unsubstituted C6-C 24 at least one of aliphatic phosphite ester.

[0095] Among them, "substituted or unsubstituted" means that the defined group can be substituted or not. When the defined group is substituted, it should be understood that the defined group can be substituted by one or more substituents.

[0096] Among them, the substituted substituents are selected from at least one of C1-C6 alkyl, C1-C6 alkoxy, and halogen.

[0097] In some embodiments, the substituted or unsubstituted C6-C 24 fatty acids include at least one of capric acid, undecylenic acid, myristic acid, oleic acid, linoleic acid, and stearic acid.

[0098] In some embodiments, the substituted or unsubstituted C6-C 24 aliphatic thiols include at least one of octanethiol, dodecyl mercaptan, and octadecyl mercaptan.

[0099] In some embodiments, the substituted or unsubstituted C6-C 24 fatty amines include at least one of oleylamine, octadecylamine, octylamine, dioctylamine, and trioctylamine.

[0100] In some embodiments, the substituted or unsubstituted C6-C 24 aliphatic phosphines include trioctylphosphine.

[0101] In some embodiments, the substituted or unsubstituted C6-C 24 aliphatic phosphine oxides include trioctylphosphine oxide.

[0102] In a second aspect, the embodiments of the present application further provide a method for preparing a composite material, including the following steps:

[0103] Step S11: Mix quantum dots, magnetic ionic liquid, and a solvent to obtain a mixed solution;

[0104] Step S12: Dry the mixed solution to obtain the composite material.

[0105] The quantum dots and the magnetic ionic liquid are as described above and will not be elaborated here.

[0106] In some embodiments, the mixing of quantum dots, magnetic ionic liquid, and a solvent to obtain a mixed solution includes:

[0107] Dissolve quantum dots in a first solvent to obtain a quantum dot solution;

[0108] Dissolve magnetic ionic liquid in a second solvent to obtain a magnetic ionic liquid solution;

[0109] Mix the quantum dot solution and the magnetic ionic liquid solution to obtain a mixed solution.

[0110] The first solvent, the second solvent, and the solvent can each independently be a low-polarity solvent, and the low-polarity solvent includes, but is not limited to, chloroform, dichloromethane, formamide, trifluoroacetic acid, dimethyl sulfoxide (DMSO), acetonitrile, N,N-dimethylformamide (DMF), hexamethylphosphoramide, acetic acid, pyridine, tetramethylethylenediamine, acetone, triethylamine, dioxane, tetrahydrofuran, methyl formate, tributylamine, methyl ethyl ketone, ethyl acetate, chloroform, trioctylamine, dimethyl carbonate, ether, isopropyl ether, n-butyl ether, trichloroethylene, diphenyl ether, dichloroethane, benzene, chlorobenzene, dichlorotoluene, toluene, carbon tetrachloride, carbon disulfide, cyclohexane, hexane, or one or more of them.

[0111] It can be understood that the amounts of the solvent, the first solvent, and the second solvent are not limited as long as the quantum dots and the magnetic ionic liquid can be fully dissolved and dispersed. In some embodiments, in the quantum dot solution, the concentration of the quantum dots is 10 - 40 mg / ml. In some embodiments, in the magnetic ionic liquid solution, the concentration of the magnetic ionic liquid is 2 - 10 mg / ml.

[0112] In some embodiments, after mixing the quantum dot solution and the magnetic ionic liquid solution, it further includes stirring for 8 - 12 h. In this way, it is beneficial to fully react the quantum dots with the magnetic ionic liquid.

[0113] In a third aspect, an embodiment of the present application further provides an ink, including a third solvent and the composite material described above.

[0114] In some embodiments, the third solvent can be a low-polarity solvent, and the low-polarity solvent includes, but is not limited to, chloroform, dichloromethane, formamide, trifluoroacetic acid, dimethyl sulfoxide (DMSO), acetonitrile, N,N-dimethylformamide (DMF), hexamethylphosphoramide, acetic acid, pyridine, tetramethylethylenediamine, acetone, triethylamine, dioxane, tetrahydrofuran, methyl formate, tributylamine, methyl ethyl ketone, ethyl acetate, chloroform, trioctylamine, dimethyl carbonate, ether, isopropyl ether, n-butyl ether, trichloroethylene, diphenyl ether, dichloroethane, benzene, chlorobenzene, dichlorotoluene, toluene, carbon tetrachloride, carbon disulfide, cyclohexane, hexane, or one or more of them.

[0115] In a fourth aspect, an embodiment of the present application further provides a film, including the composite material. It can be understood that the film can be a light-emitting film or a quantum dot film.

[0116] The embodiment of the present application also provides a method for preparing a thin film, including:

[0117] Step S01: Provide a substrate, set the ink on the substrate to obtain a wet film; and

[0118] Step S02: Apply a magnetic field to the wet film and dry it to obtain the thin film.

[0119] The ink includes the magnetic ionic liquid. The magnetic ionic liquid has magnetism and can generate a certain response to an external magnetic field under the action of its magnetic center. Thus, when using the composite material to prepare a thin film, the property that the magnetic ionic liquid has magnetism can be utilized to apply a magnetic field and adjust the sorting of quantum dots by using the external magnetic field to obtain a more orderly arranged quantum dot film.

[0120] In some embodiments, the method for applying a magnetic field to the wet film includes: placing a square magnet with a thickness of 0.5 - 1 cm and a width of 5 cm at a position 1 - 5 cm above the substrate.

[0121] The included angle range between the direction of the magnetic field and the substrate is 0 - 90°. Within this range, the magnetic ionic liquid can be subjected to a stronger magnetic field, which is beneficial to the orderly arrangement of quantum dots.

[0122] Fifth aspect, please refer to Figures 1 - 2 , the embodiment of the present application also provides a composite thin film 1, including a quantum dot layer 11 and an ionic liquid layer 12 provided on at least one surface of the quantum dot layer. Among them, the material of the quantum dot layer 11 includes quantum dots, and the material of the ionic liquid layer 12 includes magnetic ionic liquid.

[0123] The quantum dots and the magnetic ionic liquid are as described above and will not be elaborated here.

[0124] Sixth aspect, the embodiment of the present application also provides a method for preparing the composite thin film 1, including the following steps:

[0125] Step S21: Provide a substrate, set quantum dots on the substrate to form a quantum dot layer 11; and

[0126] Step S22: Set the magnetic ionic liquid on the quantum dot layer 11 to form an ionic liquid layer 12 to obtain the composite thin film 1.

[0127] The preparation method involves disposing a magnetic ionic liquid on the quantum dot layer 11. The magnetic ionic liquid can fill the gaps between the quantum dots on the surface of the quantum dot layer 11, passivating the surface defects of the quantum dot layer 11. Thus, when the composite film 1 is used in a light-emitting device, the interface defects between the quantum dot layer 11 and other film layers can be reduced, and the leakage current can be decreased, thereby improving the performance of the device such as the light-emitting efficiency and lifespan.

[0128] The embodiment of the present application also provides another preparation method for a composite film, including the following steps:

[0129] Step S31: Provide a substrate, and dispose a magnetic ionic liquid on the substrate to form an ionic liquid layer 12; and

[0130] Step S32: Dispose quantum dots on the ionic liquid layer 12 to form a quantum dot layer 11, obtaining the composite film 1.

[0131] In some embodiments, after disposing the quantum dots on the ionic liquid layer 12 to form the quantum dot layer 11, it further includes: disposing a magnetic ionic liquid on the quantum dot layer 11 to obtain another ionic liquid layer 12. At this time, the obtained composite film 1 includes the quantum dot layer 11 and the ionic liquid layers 12 disposed on the opposite two surfaces of the quantum dot layer 11.

[0132] Since quantum dots are solution-phase nanoparticles, it is not easy to control the film-forming performance, and film layer problems such as incomplete coverage or "pinholes" are likely to occur. This will not only generate leakage current in the device, reducing the light-emitting performance of the device, but most importantly, these defect areas will greatly affect the lifespan of the device. The preparation method described in the present application by preparing the quantum dot layer 11 on the ionic liquid layer 12 can improve the non-uniformity of the interface of the quantum dot layer 11 and avoid the occurrence of the "pinhole" phenomenon, thereby improving the light-emitting efficiency and service life of the device.

[0133] It can be understood that the methods of disposing the quantum dots on the substrate, disposing the magnetic ionic liquid on the quantum dot layer 11, and disposing the magnetic ionic liquid on the substrate can be implemented by conventional techniques in the art, such as chemical methods or physical methods. Among them, chemical methods include chemical vapor deposition, sequential ionic layer adsorption and reaction, anodic oxidation, electrodeposition, co-precipitation. Physical methods include physical coating methods and solution methods. Among them, physical coating methods include: thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion coating, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.; solution methods can be spin coating, printing, inkjet printing, blade coating, printing, dip coating, immersion, spraying, roll coating, casting, slot die coating, and bar coating, etc.

[0134] In at least one embodiment, the method of disposing the quantum dots on a substrate, disposing the magnetic ionic liquid on the quantum dot layer 11, and disposing the magnetic ionic liquid on the substrate may be a solution method.

[0135] In a seventh aspect, please refer to Figures 3 - 5 , an embodiment of the present application further provides a light-emitting device 100, including an anode 10, a light-emitting layer 20, and a cathode 30 that are stacked in sequence.

[0136] Please refer to Figure 3 , in some embodiments, the light-emitting layer 20 includes the composite material described above. In other words, the light-emitting layer is the thin film described above.

[0137] In some embodiments, the thickness range of the thin film is 30 to 50 nm. Within this thickness range, the electron-hole injection of the device can be made more balanced, which is beneficial to improving the light-emitting efficiency and service life of the device.

[0138] Please refer to Figure 4 , in some other embodiments, the light-emitting layer 20 is the composite thin film 1 described above. The quantum dot layer 11 of the composite thin film 1 is located on the side close to the anode 10, and the ionic liquid layer 12 is located on the side away from the anode 10.

[0139] Please refer to Figure 5 , in still some other embodiments, the light-emitting layer 20 is the composite thin film 1 described above. The quantum dot layer 11 of the composite thin film 1 is located on the side close to the cathode 30, and the ionic liquid layer 12 is located on the side away from the cathode 30.

[0140] In some embodiments, the light-emitting device 100 further includes one or several of a first carrier function layer and a second carrier function layer. The first carrier function layer is disposed between the first electrode and the light-emitting layer, and the second carrier function layer is disposed between the light-emitting layer and the second electrode.

[0141] In some embodiments, the first carrier function layer is a hole function layer, and the second carrier function layer is an electron function layer.

[0142] In some other embodiments, the second carrier function layer is a hole function layer, and the first carrier function layer is an electron function layer.

[0143] It can be understood that the hole function layer may be a hole transport layer 40, or a hole injection layer 60, or a stacked hole transport layer and hole injection layer.

[0144] It can be understood that the electron function layer may be an electron transport layer 50.

[0145] In some embodiments, the light-emitting device 100 further includes a hole transport layer 40 located between the anode 10 and the light-emitting layer 20.

[0146] In some embodiments, the light-emitting device 100 further includes an electron transport layer 50 located between the light-emitting layer 20 and the cathode 30.

[0147] In some embodiments, the light-emitting device 100 further includes a hole injection layer 60 located between the anode 10 and the hole transport layer 40.

[0148] The anode 10 and the cathode 30 are anodes and cathodes known in the art for light-emitting devices. For example, they may independently include, but are not limited to, doped metal oxide particle electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, metal elemental electrodes, or alloy electrodes. The material of the doped metal oxide particle electrode may include, but is not limited to, one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), and aluminum-doped magnesium oxide (AMO). The composite electrode is a composite electrode in which doped or undoped transparent metal oxide particles sandwich a metal, such as 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, etc. Here, " / " represents a stacked structure. For example, AZO / Ag / AZO represents a composite electrode including an AZO layer, an Ag layer, and an AZO layer stacked in sequence. The material of the metal elemental electrode may include, but is not limited to, one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba.

[0149] The material of the hole transport layer 40 may also be a material known in the art for hole transport layers, and may include, for example, but not limited to, 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NPD), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4',4'-tris(N-carbazolyl)-triphenylamine (TCTA), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine (NPB), spiro-NPB, poly(phenylene vinylene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] (MOMO-PPV), 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-omeTAD), 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC), 1,3-bis(carbazol-9-yl)benzene (MCP), polyaniline, polypyrrole, poly(p-phenylene vinylene), aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidines, 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, one or more of them.

[0150] The material of the electron transport layer 50 is a material known in the art for use in an electron transport layer, and may include, for example, but not be limited to, one or more of inorganic electron transport materials and organic electron transport materials. The inorganic electron transport materials include, for example, but not be limited to, one or more of doped metal oxide particles, undoped metal oxide particles, ceramic semiconductor materials, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The metal oxides in the undoped metal oxide particles include, for example, but not be limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5. The metal oxides in the doped metal oxide include, for example, but not be limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3, and the doping elements in the doped metal oxide include, for example, but not be limited to, one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Sn. By way of example, the doped metal oxide may be aluminum-doped zinc oxide (AZO), lithium-doped zinc oxide (LZO), magnesium-doped zinc oxide (MZO), tin-doped zinc oxide (Sn-ZnO), etc. The ceramic semiconductor materials include, for example, but not be limited to, barium titanate. The IIB-VIA group semiconductor materials include, for example, but not be limited to, one or more of ZnS, ZnSe, CdS. The IIIA-VA group semiconductor materials include, for example, but not be limited to, one or more of InP, GaP. The IB-IIIA-VIA group semiconductor materials include, for example, but not be limited to, one or more of CuInS, CuGaS. The organic electron transport materials include, for example, but not be limited to, one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds.

[0151] The material of the hole injection layer 60 may be a material known in the art for use in a hole injection layer, and may include, for example, but not be limited to, one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN), PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s-MoO3 (PEDOT:PSS:s-MoO3), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), tetracyanoquinodimethane (F4-TCQN), copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0152] In some embodiments, the thickness of the anode 10 is 10 to 120 nm; the thickness of the cathode 30 is 20 to 150 nm; the thickness of the hole transport layer 40 is 20 to 100 nm; the thickness of the electron transport layer 50 is 10 to 180 nm; the thickness of the hole injection layer 60 is 20 to 50 nm.

[0153] It can be understood that the light-emitting device 100 may further be provided with some functional layers that are conventionally used in light-emitting devices and are helpful for improving the performance of the light-emitting device, such as an electron blocking layer, a hole blocking layer, an electron injection layer, an interface modification layer, and the like.

[0154] It can be understood that the materials of the respective layers of the light-emitting device 100 can be adjusted according to the light-emitting requirements of the light-emitting device 100.

[0155] In some embodiments, the light-emitting device 100 further includes a substrate, and the substrate is disposed on a side of the anode 10 away from the light-emitting layer 20, or the substrate is disposed on a side of the cathode 30 away from the light-emitting layer 20.

[0156] The substrate may be a rigid substrate or a flexible substrate. In some embodiments, the material of the substrate may include, but is not limited to, one or more of glass, a silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0157] It can be understood that the light-emitting device 100 may be a normal light-emitting device or an inverted light-emitting device. The light-emitting device 100 may be a quantum dot light-emitting device or an organic light-emitting device.

[0158] The light-emitting layer 20 of the light-emitting device 100 includes quantum dots purified by the purification method described in the present application, and thus has a high light-emitting efficiency and a long lifespan.

[0159] In an eighth aspect, an embodiment of the present application further provides a display device, and the display device includes the light-emitting device 100.

[0160] The display device may be any electronic product having a display function, and the electronic product includes, but is not limited to, a smart phone, a tablet computer, a notebook computer, a digital camera, a digital video camera, a smart wearable device, a smart weighing electronic scale, a vehicle-mounted display, a television, or an e-book reader. Among them, the smart wearable device may be, for example, a smart bracelet, a smart watch, a virtual reality (VR) helmet, and the like.

[0161] The present application will be specifically described below through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0162] Thin Film Example 1

[0163] 30 mg of quantum dots ZnCdSe / ZnSe / ZnCdS / ZnS and 5 mg of the pure organic magnetic ionic liquid shown in formula (II-1) were added to 1 ml of n-octane to obtain a dispersion with a concentration of 35 mg / ml;

[0164] The dispersion was spin-coated on a film-forming substrate to form a wet film, and a magnetic field was applied to the wet film. Among them, the angle between the direction of the magnetic field and the substrate was 90°, and annealing was carried out at 80 °C for 10 min to obtain a thin film with a thickness of 60 nm.

[0165] Thin Film Example 2

[0166] This example is basically the same as Thin Film Example 1, except that in this example, the pure organic magnetic ionic liquid shown in formula (II-4) was used to replace the pure organic magnetic ionic liquid in Thin Film Example 1.

[0167] Thin Film Example 3

[0168] This example is basically the same as Thin Film Example 1, except that in this example, the pure organic magnetic ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was used to replace the pure organic magnetic ionic liquid in Thin Film Example 1.

[0169] Thin Film Example 4

[0170] This example is basically the same as Thin Film Example 1, except that in this example, the pure organic magnetic ionic liquid shown in formula (I-3) was used to replace the pure organic magnetic ionic liquid in Thin Film Example 1.

[0171] Thin Film Example 5

[0172] This example is basically the same as Thin Film Example 1, except that in this example, the magnetic ionic liquid containing metal element [nbmp][FeCl4] was used to replace the pure organic magnetic ionic liquid in Thin Film Example 1.

[0173] Thin Film Example 6

[0174] This example is basically the same as Thin Film Example 1, except that in this example, the magnetic ionic liquid containing metal element [C4mim][Co(hfacac)3] was used to replace the pure organic magnetic ionic liquid in Thin Film Example 1.

[0175] Thin Film Example 7

[0176] This example is basically the same as Thin Film Example 1, except that in this example, the magnetic ionic liquid containing metal element [C6min] 5-x [Dy(SCN)8-x (H2O) x Replace the pure organic magnetic ionic liquid in Film Example 1.

[0177] Film Example 8

[0178] This example is basically the same as Film Example 1, except that in this example, the mass ratio of the pure organic magnetic ionic liquid to the quantum dots is 2:30.

[0179] Film Example 9

[0180] This example is basically the same as Film Example 1, except that in this example, the mass ratio of the pure organic magnetic ionic liquid to the quantum dots is 10:30.

[0181] Film Example 10

[0182] This example is basically the same as Film Example 1, except that in this example, InP / ZnSe / ZnS quantum dots are used to replace the ZnCdSe / ZnSe / ZnCdS / ZnS quantum dots in Film Example 1.

[0183] Film Example 11

[0184] This example is basically the same as Film Example 1, except that in this example, ZnSe / ZnCdSe / ZnCdS / ZnS quantum dots are used to replace the ZnCdSe / ZnSe / ZnCdS / ZnS quantum dots in Film Example 1.

[0185] Film Example 12

[0186] Spin-coat the pure organic magnetic ionic liquid shown in formula (II-1) with a concentration of 5 mg / ml (the solvent is n-octane) on the film-forming substrate, and anneal at 100 °C for 20 min to obtain an ionic liquid layer 12 with a thickness of 10 nm;

[0187] Spin-coat a ZnCdSe / ZnSe / ZnCdS / ZnS quantum dot solution with a concentration of 30 mg / ml (the solvent is n-octane) on the ionic liquid layer 12, and anneal at 80 °C for 10 min to obtain a quantum dot layer 11 with a thickness of 30 nm, and obtain a composite film 1 including the quantum dot layer 11 and the ionic liquid layer 12.

[0188] Film Example 13

[0189] This example is basically the same as Film Example 12, except that in this example, the pure organic magnetic ionic liquid shown in formula (II-4) is used to replace the pure organic magnetic ionic liquid in Example 12.

[0190] Film Example 14

[0191] This example is basically the same as Thin Film Example 12, except that in this example, the pure organic magnetic ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate is used to replace the pure organic magnetic ionic liquid in the example.

[0192] Thin Film Example 15

[0193] This example is basically the same as Thin Film Example 12, except that in this example, the magnetic ionic liquid [C6min] 5-x [Dy(SCN) 8-x (H2O) x is used to replace the pure organic magnetic ionic liquid [Cmim][TEMPO-OSO3] in Thin Film Example 12.

[0194] Thin Film Example 16

[0195] This example is basically the same as Thin Film Example 12, except that in this example, the magnetic ionic liquid containing metal elements [C4mim][M”(hfacac)4] is used to replace the pure organic magnetic ionic liquid in Thin Film Example 12.

[0196] Thin Film Example 17

[0197] This example is basically the same as Thin Film Example 1, except that in this example, InP / ZnSe / ZnS quantum dots are used to replace the ZnCdSe / ZnSe / ZnCdS / ZnS quantum dots in Thin Film Example 12.

[0198] Thin Film Example 18

[0199] This example is basically the same as Thin Film Example 12, except that in this example, ZnSe / ZnCdSe / ZnCdS / ZnS quantum dots are used to replace the ZnCdSe / ZnSe / ZnCdS / ZnS quantum dots in Thin Film Example 12.

[0200] Thin Film Example 19

[0201] This example is basically the same as Thin Film Example 12, except that in this example, the ionic liquid layer 12 is prepared first, and then the quantum dot layer 11 is prepared. That is, the preparation method of the composite film in this example includes:

[0202] Spin-coating a ZnCdSe / ZnSe / ZnCdS / ZnS quantum dot solution with a concentration of 30 mg / ml (the solvent is n-octane) on a film-forming substrate, and annealing at 80 °C for 40 min to obtain a quantum dot layer 11 with a thickness of 30 nm;

[0203] The pure organic magnetic ionic liquid shown in formula (II-1) with a concentration of 5 mg / ml (using n-octane as the solvent) was spin-coated on the quantum dot layer 11 and annealed at 100 °C for 20 min to obtain an ionic liquid layer 12 with a thickness of 10 nm, and a composite film 1 including the quantum dot layer 11 and the ionic liquid layer 12 was obtained.

[0204] Film Example 20

[0205] This example is basically the same as Film Example 12, except that in this example, after the quantum dot layer 11 is prepared, it further includes:

[0206] The pure organic magnetic ionic liquid shown in formula (II-1) with a concentration of 2.5 mg / ml (using n-octane as the solvent) was spin-coated on the quantum dot layer 11 and annealed at 100 °C for 20 min to obtain another ionic liquid layer 12 with a thickness of 5 nm, and a composite film 1 including the ionic liquid layer 12, the quantum dot layer 11, and the ionic liquid layer 12 stacked in sequence was obtained.

[0207] Film Example 21

[0208] This example is basically the same as Film Example 1, except that in this example, the angle between the direction of the magnetic field and the substrate is 0°.

[0209] Film Comparative Example 1

[0210] This comparative example is basically the same as Film Example 1, except that in this comparative example, the light-emitting layer does not include a magnetic ionic liquid but includes the quantum dots in Film Example 1.

[0211] Film Comparative Example 2

[0212] This comparative example is basically the same as Film Example 10, except that in this comparative example, the light-emitting layer does not include a magnetic ionic liquid but includes the quantum dots in Film Example 10.

[0213] Film Comparative Example 3

[0214] This comparative example is basically the same as Film Example 11, except that in this comparative example, the light-emitting layer does not include a magnetic ionic liquid but includes the quantum dots in Film Example 11.

[0215] The roughness of the upper surfaces of the films in Film Examples 1 to 21 and Film Comparative Examples 1 to 3 was detected respectively, and the detection results are shown in Table 1.

[0216] Table 1:

[0217]

[0218]

[0219] Among them, in the roughness data, for Film Examples 1-11 and 21, it is the roughness of the surface of the film away from the film-forming substrate; for Film Examples 12-18, it is the roughness of the surface of the quantum dot layer away from the film-forming substrate; for Example 19, it is the roughness of the surface of the ionic liquid layer away from the film-forming substrate; for Example 20, it is the roughness of the surface of the uppermost ionic liquid layer away from the film-forming substrate.

[0220] As can be seen from Table 1, compared with the films of Comparative Examples 1-3, the roughness of the upper surface of the films of Examples 1-21 is significantly lower. The reason may be that the dispersion liquid used in the preparation of the films of Examples 1-21 includes magnetic ionic liquid. When using the composite material to prepare the film, the quantum dots in the film layer can be tightly bonded, and the quantum dots are not likely to agglomerate, which is beneficial to making the prepared film uniform and smooth, and can effectively improve the film-forming morphology of the film and reduce the surface defects of the film; further, the magnetic ionic liquid has magnetism, and under the action of its magnetic center, it can produce a certain response to the external magnetic field. Thus, when using the composite material to prepare the film, the property of the magnetic ionic liquid having magnetism can be utilized to apply a magnetic field and adjust the sorting of the quantum dots by the external magnetic field to obtain a quantum dot film with a more orderly arrangement.

[0221] Device Example 1

[0222] Provide a glass substrate, deposit indium tin oxide (ITO) material on the glass substrate to obtain an ITO anode 10 with a thickness of 100 nm;

[0223] Spin-coat PEDOT:PSS material on the anode 10 and anneal at 150 °C for 20 min to obtain a hole injection layer 60 with a thickness of 50 nm;

[0224] Spin-coat TFB material with a concentration of 8 mg / mL on the hole injection layer 60 and anneal at 200 °C for 30 min to obtain a hole transport layer 40 with a thickness of 50 nm;

[0225] Use the preparation method of Film Example 1 to prepare a film on the hole transport layer 40 to obtain a light-emitting layer 20, that is, the light-emitting layer 20 of this example is the film of Film Example 1;

[0226] Spin-coat an ethanol solution of ZnO with a concentration of 20 mg / ml on the light-emitting layer 20 and anneal at 80 °C for 10 min to obtain an electron transport layer 50 with a thickness of 60 nm;

[0227] Evaporate Ag on the electron transport layer 50 to obtain a cathode 30 with a thickness of 120 nm;

[0228] Encapsulate to obtain a light-emitting device 100.

[0229] Device Embodiments 2 to 21

[0230] Device Embodiments 2 to 21 are basically the same as Device Embodiment 1, except that the light-emitting layers 20 of Device Embodiments 2 to 21 are respectively prepared by the preparation methods of Film Embodiments 2 to 21, that is, the light-emitting layers 20 of Device Embodiments 2 to 21 are respectively the films of Film Embodiments 2 to 21.

[0231] Device Comparative Examples 1 to 3

[0232] Device Comparative Examples 1 to 3 are basically the same as Device Embodiment 1, except that the light-emitting layers of Device Comparative Examples 1 to 3 are respectively prepared by the preparation methods of Film Comparative Examples 1 to 3, that is, the light-emitting layers of Device Comparative Examples 1 to 3 are respectively the films of Film Comparative Examples 1 to 3.

[0233] The maximum external quantum efficiency EQE max of the light-emitting devices in Device Embodiments 1 to 21 and Device Comparative Examples 1 to 3, turn-on voltage, and lifetime T95@1000nit were tested. The test results are shown in Table 1. Among them, the lower the turn-on voltage, the better the conductivity of the composite material.

[0234] Maximum external quantum efficiency EQE max The test method is as follows: Using a FushiDa FPD optical property measurement device, an efficiency test system built by controlling a QE PRO spectrometer, Keithley 2400, and Keithley 6485 through LabView, parameters such as voltage, current, brightness, and emission spectrum were measured to obtain the maximum brightness L max , and the external quantum efficiency EQE of the device was obtained by calculation. The specific calculation formula is as follows:

[0235]

[0236] In the formula, ηe is the optical output coupling efficiency, ηr is the ratio of the number of recombined carriers to the number of injected carriers, χ is the ratio of the number of excitons generating photons to the total number of excitons, KR is the rate of the radiative process, and KNR is the rate of the non-radiative process.

[0237] The test method for the turn-on voltage is as follows: The voltage value when the brightness reaches 1nit was obtained from the efficiency test system built by Keithley 6485, which is the turn-on voltage.

[0238] The test method for the lifetime T95@1000nit is as follows: in CDA gas, under the drive of a constant current or voltage, the time it takes for the device brightness to decay to a certain proportion of the maximum brightness is measured. The time when the brightness decays to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the lifetime test cycle, the device lifetime test is usually carried out by accelerating device aging at high brightness, and the lifetime at low brightness is obtained by fitting with an attenuation fitting formula. For example, the lifetime at 1000nits is denoted as T95@1000nits, and the calculation formula is:

[0239]

[0240] where T95 L is the lifetime at low brightness, generally taking the lifetime at 1000nits, and T95 H is the lifetime at high brightness, that is, the measured lifetime, and L H is the maximum brightness to which the device is accelerated, and L L is generally 1000nits, A is the acceleration factor, taking 1.7. Among them, the constant current is 2mA.

[0241] Table II:

[0242] <![CDATA[EQE max (%)]]> Turn - on voltage (V) T95@1000nits (h) Device Example 1 15.2 4.68 57.2 Device Example 2 15.0 4.72 53.2 Device Example 3 15.2 4.32 56.8 Device Example 4 16.2 4.26 58.3 Device Example 5 16.5 4.15 60.8 Device Example 6 16.1 4.26 59.4 Device Example 7 15.9 4.38 57.9 Device Example 8 14.6 5.0 43.8 Device Example 9 14.6 5.2 43.0 Device Example 10 13.7 5.2 48.2 Device Example 11 15.0 4.48 55.6 Device Example 12 14.6 4.86 49.8 Device Example 13 14.9 4.62 49.2 Device Example 14 15.0 4.76 48.3 Device Example 15 15.6 4.32 57.6 Device Example 16 15.9 4.24 60.5 Device Example 17 14.1 5.0 46.5 Device Example 18 15.4 4.42 51.8 Device Example 19 14.8 4.49 56.8 Device Example 20 17.2 4.0 72.6 Device Example 21 14.6 4.86 47.8 Device Comparative Example 1 14.5 5.1 42.8 Device Comparative Example 2 10.5 5.6 30.2 Device Comparative Example 3 14.1 4.6 50.3

[0243] It can be seen from Table II that:

[0244] Compared with the light-emitting devices of device comparative example 1, the light-emitting devices of device examples 1-9 and 21 have a lower turn-on voltage, a higher EQE max , and a longer lifetime; compared with the light-emitting devices of device comparative example 2, the light-emitting devices of device example 10 have a lower turn-on voltage, a higher EQE max , and a longer lifetime; compared with the light-emitting devices of device comparative example 3, the light-emitting devices of device example 11 have a lower turn-on voltage, a higher EQE max , and a longer lifetime. It can be seen that the light-emitting layer prepared from the composite material of the present application has good conductivity, which can enable the light-emitting device to have a lower turn-on voltage, a higher EQE max , and a longer lifetime. The reason may be that: the composite material described in the present application includes the quantum dots and the coordination linker, and the magnetic ionic liquid on the quantum dots. The magnetic ionic liquid can effectively improve the film-forming morphology of the film, reduce the surface defects of the film, and thus improve the problem of serious device lifetime decay; further, the magnetic ionic liquid has high conductivity, which can reduce the transport barrier of carriers inside the device to a certain extent, improve the utilization rate of carriers, and thus improve the light-emitting performance of the device.

[0245] Compared with the light-emitting devices of Device Comparative Example 1, the light-emitting devices of Device Examples 12-16 and 19-20 have a lower turn-on voltage, a higher EQE max , and a longer lifespan; compared with the light-emitting devices of Device Comparative Example 2, the light-emitting devices of Device Example 17 have a lower turn-on voltage, a higher EQE max , and a longer lifespan; compared with the light-emitting devices of Device Comparative Example 3, the light-emitting devices of Device Example 18 have a lower turn-on voltage, a higher EQE max , and a longer lifespan. It can be seen that the composite film composed of the ionic liquid layer and the quantum dots as the light-emitting layer can make the light-emitting device have a lower turn-on voltage, a higher EQE max , and a longer lifespan. The reason may be that a magnetic ionic liquid is provided on the quantum dot layer. The magnetic ionic liquid can fill the gaps between the quantum dots on the surface of the quantum dot layer, passivate the surface defects of the quantum dot layer, reduce the interface defects between the quantum dot layer and other film layers, and reduce the leakage current, thereby improving the performance of the device such as the light-emitting efficiency and lifespan; while preparing the quantum dot layer on the ionic liquid layer can improve the unevenness of the quantum dot layer interface and avoid the occurrence of the "pinhole" phenomenon, thereby improving the light-emitting efficiency and service life of the device.

[0246] The technical solutions provided in the embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principles and implementation manners of the present application. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A composite material, characterized in that, It includes quantum dots and magnetic ionic liquids.

2. The composite material according to claim 1, wherein in the composite material, the mass ratio of the magnetic ionic liquid to the quantum dots is (1 - 5):15; and / or, the magnetic ionic liquid includes one or more of pure organic magnetic ionic liquids and magnetic ionic liquids containing metal elements.

3. The composite material according to claim 2, wherein, The pure organic magnetic ionic liquid includes one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, the compound shown in formula (I), and the compound shown in formula (II); wherein, R1 and R2 are each independently selected from one or more of H, substituted or unsubstituted C1 - C20 alkyl groups, and the substituents of the substituted ones are selected from deuterium, amino group, halogen, hydroxyl group, carboxyl group, nitro group, aldehyde group, cyano group, C1 - C6 alkyl groups, C1 - C6 alkoxy groups, C1 - C6 alkoxycarbonyl groups, C1 - C6 alkyl acyloxy groups; and / or, the magnetic ionic liquid containing metal elements includes one or more of magnetic ionic liquids containing transition metal elements and magnetic ionic liquids containing lanthanide metal elements.

4. The composite material according to claim 3, wherein R1 and R2 are each independently selected from one or more of H, C1 - C10 straight-chain alkyl groups; and / or, the chemical formula of the metal element-containing magnetic ionic liquid is A m M n ; wherein, m and n are natural numbers; A is selected from one or more of alkyl-substituted imidazolium cations, alkyl-substituted pyrrolidinium cations, and alkyl-substituted pyridinium cations; M is selected from one or more of tetrahaloferrate anions, tris(hexafluoroacetylacetonato)transition metal anions, and tris(hexafluoroacetylacetonato)lanthanide metal anions.

5. The composite material according to claim 4, wherein the alkyl-substituted imidazolium cation includes one or more of 1-butyl-3-methylimidazolium cation, 1-ethyl-3-methylimidazolium cation, and 1-methyl-3-alkylimidazolium cation; and / or, the alkyl-substituted pyrrolidinium cation includes 1-butyl-1-methylpyrrolidinium cation; and / or, the alkyl-substituted pyridinium cation includes 1-butylpyridinium cation; And / or, the iron tetrahalide anion includes [FeCl4] - , [FeBr4] - , [FeCl4] - , [FeF4] - , [FeCl3Br] - One or more of the following; and / or, the tris(hexafluoroacetylacetonato)transition metal anion includes one or more of tris(hexafluoroacetylacetonato)cobalt anion, tris(hexafluoroacetylacetonato)manganese anion, and tris(hexafluoroacetylacetonato)nickel anion; and / or, the tris(hexafluoroacetylacetonato)lanthanide metal anion includes one or more of tris(hexafluoroacetylacetonato)dysprosium anion, tris(hexafluoroacetylacetonato)gadolinium anion, and tris(hexafluoroacetylacetonato)neodymium anion; and / or, the magnetic ionic liquid containing transition metal elements includes one or more of 1-butyl-3-methylimidazolium tetrachloride, 1-butyl-1-methylpyrrolidinium tetrachloride, 1-butylpyridinium tetrachloride, 1-ethyl-3-methylimidazolium tetrachloride, 1-methyl-3-alkylimidazolium tetrachloride, 1-butyl-3-methylimidazolium bromochloride, 1-butyl-3-methylimidazolium tris(hexafluoroacetylacetonato)cobalt, 1-butyl-3-methylimidazolium tris(hexafluoroacetylacetonato)manganese, and 1-butyl-3-methylimidazolium tris(hexafluoroacetylacetonato)nickel; And / or, the lanthanide metal element-containing magnetic ionic liquid includes one or more of dysprosium hexylmethylimidazolium thiocyanate, dysprosium 1-methyl-3-alkyldiimidazolium thiocyanate, dysprosium 1-ethyl-3-methylimidazolium tetrachloride, dysprosium tris(hexafluoroacetylacetonate) 1-butyl-3-methylimidazolium, gadolinium tris(hexafluoroacetylacetonate) 1-butyl-3-methylimidazolium, and neodymium tris(hexafluoroacetylacetonate) 1-butyl-3-methylimidazolium.

6. The composite material according to claim 1, wherein The quantum dots include one or more of single-structure quantum dots, core-shell structure quantum dots, perovskite semiconductor materials, silicon quantum dots, and germanium quantum dots. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots include one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds include one or more 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 include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The III-V group compounds include 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, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb. The I-III-VI group compounds include one or more of CuInS2, CuInSe2, and AgInS2. The perovskite semiconductor materials include doped or undoped inorganic perovskite semiconductor materials or organic-inorganic hybrid perovskite semiconductor materials. The structural general formula of the inorganic perovskite semiconductor materials is AMX3, where A is Cs + ions, 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, X is a halogen anion, including Cl - , Br - , I - one or more of, the structural general 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, X is a halogen anion, including Cl - , Br - , I - one or more of; And / or, the average particle size range of the quantum dots is 8 to 15 nm; And / or, ligands are connected to the surface of the quantum dots, and the ligands include substituted or unsubstituted C6-C 24 fatty acids, substituted or unsubstituted C6-C 24 fatty amines, substituted or unsubstituted C6-C 24 aliphatic thiols, substituted or unsubstituted C6-C 24 aliphatic thioethers, substituted or unsubstituted C6-C 24 aliphatic phosphines, substituted or unsubstituted C6-C 24 aliphatic phosphine oxides, substituted or unsubstituted C8-C 20 aliphatic phosphoric acids, substituted or unsubstituted C6-C 24 aliphatic phosphates, substituted or unsubstituted C6-C 24 aliphatic phosphorous acids, and substituted or unsubstituted C6-C 24 at least one of aliphatic phosphites, Optionally, the substituted or unsubstituted C6-C 24 fatty acids include at least one of capric acid, undecylenic acid, myristic acid, oleic acid, linoleic acid, and stearic acid; Optionally, the substituted or unsubstituted C6-C 24 aliphatic thiols include at least one of octanethiol, dodecyl mercaptan, octadecyl mercaptan; Optionally, the substituted or unsubstituted C6-C 24 The fatty amine includes at least one of oleylamine, octadecylamine, octylamine, dioctylamine, and trioctylamine; Optionally, the substituted or unsubstituted C6-C 24 aliphatic phosphines include trioctylphosphine; Optionally, the substituted or unsubstituted C6-C 24 aliphatic oxygen phosphine includes trioctyl phosphine oxide.

7. A film, characterized in that, The material of the thin film includes the composite material according to any one of claims 1 to 6.

8. A composite film, characterized in that, It includes a quantum dot layer and an ionic liquid layer provided on at least one surface of the quantum dot layer. Among them, the material of the quantum dot layer includes quantum dots, and the material of the ionic liquid layer includes the magnetic ionic liquid according to any one of claims 3 to 5.

9. A light-emitting device, the light-emitting device comprising a first electrode, a light-emitting layer, and a second electrode stacked in sequence, characterized in that, The light-emitting layer includes the composite material according to any one of claims 1 to 6, or the light-emitting layer is the thin film according to claim 7, or the light-emitting layer is the composite thin film according to claim 8.

10. The light-emitting device according to claim 9, characterized in that, The light-emitting device further includes one or several of a first carrier function layer and a second carrier function layer. The first carrier function layer is provided between the first electrode and the light-emitting layer, and the second carrier function layer is provided between the light-emitting layer and the second electrode; the first carrier function layer is a hole function layer, and the second carrier function layer is an electron function layer; or the second carrier function layer is a hole function layer, and the first carrier function layer is an electron function layer; Optionally, the first electrode and the second electrode each independently include one or several of a metal, a carbon material, and a metal oxide; the metal includes one or several of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes one or several of graphite, carbon nanotubes, graphene, and carbon fibers; the metal oxide includes a metal oxide electrode or a composite electrode with a metal disposed between doped or undoped transparent metal oxides. The material of the metal oxide electrode includes one or several of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3, and AMO. The composite electrode includes one or several of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2; Optionally, the material of the hole functional layer includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent material, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 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(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS derivatives doped with s-MoO3, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine, spiro-NPB, nanocrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfides, metal selenides and metal nitrides, the metal oxides in the second doped metal oxide particles and the metal oxides in the second undoped metal oxide particles each independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, V2O5, the doping elements in the second doped metal oxide particles include one or more of Mo, W, Ni, Cr, Cu, V, the metal sulfides include one or more of CuS, MoS3, WS3, the metal selenides include one or more of MoSe3, WSe3, and the metal nitrides include p-type gallium nitride; Optionally, the material of the electronic functional layer includes one or more of first doped metal oxide particles, first undoped metal oxide particles, Group IIB-VIA semiconductor materials, Group IIIA-VA semiconductor materials, and Group IB-IIIA-VIA semiconductor materials. The material of the first undoped metal oxide particles includes one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5. The metal oxides in the first doped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3. The doping elements in the first doped metal oxide particles include one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga. The Group IIB-VIA semiconductor materials include one or more of ZnS, ZnSe, CdS. The Group IIIA-VA semiconductor materials include one or more of InP, GaP. The Group IB-IIIA-VIA semiconductor materials include one or more of CuInS, CuGaS.

Images