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

Abstract

The invention discloses a composite material, a thin film, a light-emitting device and a display device. The composite material comprises N-type inorganic nanoparticles and metal nanoclusters. The metal nanoclusters can modify the surfaces of the N-type inorganic nanoparticles, so that the surface defects of the N-type inorganic nanoparticles are reduced, and the electron transmission efficiency of the N-type inorganic nanoparticles is further improved.

Description

Technical Field

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

[0002] Currently, the widely used light-emitting devices are organic light-emitting devices (OLEDs) and quantum dot light-emitting devices (QLEDs). Due to their excellent display performances such as self-luminescence, simple structure, ultra-thinness, fast response speed, wide viewing angle, low power consumption, and flexible display, OLEDs have become the mainstream technology in the display technology field. QLEDs have the advantages of saturated emission light color, adjustable wavelength, low turn-on voltage, good solution processability, easy fine control of quantum dots, etc., and have high photoluminescence and electroluminescence quantum yields, and have become a strong competitor of OLEDs in recent years.

[0003] The structures of traditional OLED and QLED devices generally include an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode. Under the action of an electric field, the holes generated by the anode and the electrons generated by the cathode of the light-emitting device move, are respectively injected into the hole transport layer and the electron transport layer, and finally migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, thereby exciting the light-emitting molecules to finally generate visible light.

[0004] N-type inorganic nanoparticles are used as electron transport materials due to their good electron transport performance.

[0005] However, the carrier transport efficiency of existing N-type inorganic nanoparticles is not high enough, and the device performance needs to be further improved. Summary of the Invention

[0006] In view of this, the present application provides a preparation method of a composite material, aiming to improve the problem that the electron transport efficiency of the existing materials of the electron transport layer is not high enough.

[0007] In a first aspect, the present application provides a composite material, which includes N-type inorganic nanoparticles and metal nanoclusters.

[0008] Optionally, in some embodiments, the metal nanoclusters include a metal core and ligands coordinately connected to the metal core, and the metal core includes n metal atoms, where n is an integer from 1 to 1000.

[0009] Optionally, in some embodiments, the metal nanoclusters are coordinately connected to the N-type inorganic nanoparticles; and / or

[0010] the average particle size of the metal nanoclusters is 1 to 10 nm; and / or

[0011] The average particle size of the N-type inorganic nanoparticles is 5-8 nm; and / or

[0012] The conduction band energy level of the composite material is 3.6-4.0 eV; and / or

[0013] The metal atoms include noble metal atoms, and the noble metal atoms include one or more of gold atoms, silver atoms, and platinum atoms;

[0014] The ligands include organic ligands and / or inorganic ligands. The organic ligands include one or more of thiol compounds, polymer polymers, and amino acids. Among them, the thiol compounds include one or more of dimercaptohexane, 1-mercapto-2-propanone, and undecanethiol. The amino acids include one or more of N-acetyl-L-cysteine, methionine, cysteine, N-acetyl-L-lysine, and N-acetyl-L-glutamic acid; the inorganic ligands include one or more of sulfides, phosphides, selenides, and tellurides. The sulfides include one or more of sodium sulfide, hydrogen sulfide, ammonium sulfide, and carbon disulfide. The phosphides include one or more of phosphine and sodium phosphide. The selenides include one or more of sodium selenide and cuprous selenide. The tellurides include one or more of cuprous telluride and zinc telluride.

[0015] Optionally, in some embodiments, the metal nanoclusters include one or more of gold nanoclusters, silver nanoclusters, and platinum nanoclusters, wherein

[0016] The gold nanoclusters include one or more of dimercaptohexane gold nanoclusters, 1-mercapto-2-propanone gold nanoclusters, undecanethiol gold nanoclusters, N-acetyl-L-cysteine gold nanoclusters, methionine gold nanoclusters, cysteine gold nanoclusters, N-acetyl-L-lysine gold nanoclusters, and N-acetyl-L-glutamic acid gold nanoclusters; and / or

[0017] The silver nanoclusters include one or more of dimercaptohexane silver nanoclusters, 1-mercapto-2-propanone silver nanoclusters, undecanethiol silver nanoclusters, N-acetyl-L-cysteine silver nanoclusters, methionine silver nanoclusters, cysteine silver nanoclusters, N-acetyl-L-lysine silver nanoclusters, and N-acetyl-L-glutamic acid silver nanoclusters; and / or

[0018] The platinum nanoclusters include one or more of dimercaptohexane platinum nanoclusters, 1-mercapto-2-propanone platinum nanoclusters, undecanethiol platinum nanoclusters, N-acetyl-L-cysteine platinum nanoclusters, methionine platinum nanoclusters, cysteine platinum nanoclusters, N-acetyl-L-lysine platinum nanoclusters, and N-acetyl-L-glutamic acid platinum nanoclusters.

[0019] Optionally, in some embodiments, in the metal nanoclusters, the molar ratio of the metal atoms to the ligands ranges from 1:(5-10).

[0020] Optionally, in some embodiments, the N-type inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the undoped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5. The metal oxides in the doped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3. The doping elements in the doped metal oxide particles include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga. The IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, CdS. The IIIA-VA group semiconductor materials include one or more of InP, GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS, CuGaS.

[0021] Optionally, in some embodiments, the molar ratio of the N-type inorganic nanoparticles to the metal nanoclusters ranges from 1:(0.01-0.1).

[0022] In a second aspect, the present application also provides a thin film, which includes the above composite material.

[0023] In a third aspect, the present application also provides a light-emitting device, which includes an anode and a cathode disposed opposite to each other, and a light-emitting layer located between the anode and the cathode. The light-emitting device further includes an electron transport layer, which is located between the light-emitting layer and the cathode, and the material of the electron transport layer includes the above composite material.

[0024] Optionally, in some embodiments, the anode and the cathode each independently comprise a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal elemental electrode, or an alloy electrode. The material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the metal elemental electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba; and / or

[0025] 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 includes 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, 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, polymer containing B-N covalent bond, hybrid local charge transfer excited state material, exciplex luminescent material, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives;The quantum dot light-emitting material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. 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 are each independently selected from 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 material includes 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, including Pb 2+ , Sn 2+ , Cu 2+ , Ni2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ One or more of 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; and / or

[0026] The light-emitting device further includes a hole transport layer on a side of the light-emitting layer away from the electron transport layer, and the material of the hole transport layer includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiro-NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-phenylene vinylene), aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or

[0027] The light-emitting device further includes a hole injection layer on a side of the light-emitting layer away from the electron transport layer, and the material of the hole injection layer includes one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0028] Fourthly, the present application further provides a display device including the above-mentioned light-emitting device.

[0029] The composite material described in the present application includes N-type inorganic nanoparticles and metal nanoclusters. The metal nanoclusters can modify the surface of the N-type inorganic nanoparticles, reduce the surface defects of the N-type inorganic nanoparticles, and further improve the electron transport efficiency of the N-type inorganic nanoparticles, thereby improving the light-emitting efficiency of the light-emitting device. Description of the Drawings

[0030] 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 drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 is a flowchart of a method for preparing a thin film provided by an embodiment of the present application;

[0032] Figure 2 is a schematic structural diagram of a light-emitting device provided by an embodiment of the present application;

[0033] Figure 3 is a schematic structural diagram of another light-emitting device provided by an embodiment of the present application;

[0034] Figure 4 is a schematic structural diagram of yet another light-emitting device provided by an embodiment of the present application;

[0035] Figure 5 is a schematic structural diagram of yet another light-emitting device provided by an embodiment of the present application;

[0036] Figure 6 is a schematic structural diagram of yet another light-emitting device provided by an embodiment of the present application;

[0037] Figure 7 is a schematic structural diagram of yet another light-emitting device provided by an embodiment of the present application;

[0038] Figure 8 This is a flowchart of a method for manufacturing a light-emitting device provided by an embodiment of the present application.

[0039] Reference numerals:

[0040] Light-emitting device 100; first electrode 10; electron transport layer 20; second electrode 30; light-emitting layer 40; hole transport layer 50; hole injection layer 60. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with 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 in 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" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings; and "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" 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.

[0043] 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. Where A and B may be singular or plural.

[0044] 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 (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) among a, b, or c", or, "at least one item (piece) among a, b, and c" can all 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.

[0045] 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 the certain layer, or it can mean that there are other spacer structure layers between the another layer and the certain layer. For example, when forming a second electrode "on" the first charge carrier functional layer, the so-called "on" can mean that the formed second electrode is adjacent to the first charge carrier functional layer, or it can mean that there are other spacer structure layers between the second electrode and the first charge carrier functional layer, such as a light-emitting layer.

[0046] 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 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 numbers (fractions or integers) within the indicated range.

[0047] N-type inorganic nanoparticles are considered to be one of the most popular materials for preparing the electron transport layer of high-efficiency light-emitting devices due to their high electron mobility and hole-blocking properties. However, for hole-excessive devices, such as quantum dot light-emitting diodes emitting blue light, the injection and transport efficiency of electrons is less than that of holes, especially during long-term current aging, and the gap in carrier injection is more obvious. On the one hand, it will cause an imbalance in electron-hole injection, resulting in device efficiency roll-off and / or short lifetime; on the other hand, there are many surface defect states on the N-type inorganic nanoparticles, and when in direct contact with the quantum dot layer, exciton quenching is likely to occur at the interface, thereby affecting the efficiency of the device.

[0048] The technical solution of the present application is as follows:

[0049] In a first aspect, an embodiment of the present application provides a composite material, including N-type inorganic nanoparticles and metal nanoclusters. The metal nanoclusters are coordinatively connected to the N-type inorganic nanoparticles.

[0050] The metal nanoclusters include a metal core and ligands coordinatively connected to the metal core, and the metal core includes n metal atoms, where n is an integer from 1 to 1000.

[0051] Metal nanoclusters are usually composed of metal atoms and ligands. The metal atoms form the core structure of the cluster, while the ligands are connected to the metal atoms through coordination bonds and stabilize the structure of the metal nanoclusters. Therefore, metal nanoclusters refer to nanoscale aggregates composed of metal atoms and ligands. Metal nanoclusters are intermediate in size and structure between single atoms and nanoparticles. Metal nanoclusters usually contain organic or inorganic ligands. These ligands can have an important impact on the stability, morphology, and properties of metal nanoclusters. The ligands can stabilize the structure of metal nanoclusters by forming coordination bonds with metal atoms.

[0052] Due to the unique structure of surface ligands and metal cores, metal nanoclusters have ligand properties and metallic properties. Thus, on the one hand, metal nanoclusters can modify the surface of the N-type inorganic nanoparticles, reduce surface defects of the N-type inorganic nanoparticles, and thereby improve the electron transport efficiency of the N-type inorganic nanoparticles; on the other hand, metal nanoclusters can also improve the conductivity of the composite material, thereby further enhancing the electron transport efficiency of the N-type inorganic nanoparticles; furthermore, metal nanoclusters also have strong polarization ability and can change the conduction band energy level corresponding to the electron functional layer prepared from the composite material through π-π interactions between molecules, thereby adjusting the energy level structure of the electron functional layer and further enhancing the electron transport efficiency; in addition, the metal clusters can also form an interfacial dipole with the N-type inorganic nanoparticles to regulate the injection barrier of carriers and thus enhance the injection efficiency of electrons.

[0053] The metal atoms include noble metal atoms, and the noble metal atoms include one or more of, but are not limited to, gold atoms, silver atoms, and platinum atoms. On the one hand, the noble metal atoms have good conductivity and can improve the conductivity of the composite material, thereby further enhancing the electron transport efficiency of the N-type inorganic nanoparticles; on the other hand, the interaction between the noble metal atoms is strong, which helps to maintain the cluster structure, making the metal nanoclusters have high stability, and thus making the composite material have high stability.

[0054] The ligand includes an organic ligand and / or an inorganic ligand. The organic ligand includes, but is not limited to, one or more of thiol compounds, polymer polymers, and amino acids. Among them, the thiol compound includes, but is not limited to, one or more of dimercaptohexane, 1-mercapto-2-propanone, undecanethiol. The amino acid includes, but is not limited to, one or more of N-acetyl-L-cysteine, methionine, cysteine, N-acetyl-L-lysine, N-acetyl-L-glutamic acid. The inorganic ligand includes, but is not limited to, one or more of sulfides, phosphides, selenides, tellurides. The sulfide includes, but is not limited to, one or more of sodium sulfide (Na2S), hydrogen sulfide (H2S), ammonium sulfide ((NH4)2S), carbon disulfide (CS2). The phosphide includes, but is not limited to, one or more of phosphine (PH3), sodium phosphide (Na3P). The selenide includes, but is not limited to, one or more of sodium selenide (Na2Se), copper selenide (Cu2Se). The telluride includes, but is not limited to, one or more of copper telluride (Cu2Te), zinc telluride (ZnTe).

[0055] In some embodiments, the metal nanoclusters include, but are not limited to, one or more of gold nanoclusters (AuNCs), silver nanoclusters, and platinum nanoclusters.

[0056] As an example, the gold nanoclusters include, but are not limited to, one or more of dimercaptohexane gold nanoclusters, 1-mercapto-2-propanone gold nanoclusters, undecanethiol gold nanoclusters, N-acetyl-L-cysteine gold nanoclusters, methionine gold nanoclusters, cysteine gold nanoclusters, N-acetyl-L-lysine gold nanoclusters, N-acetyl-L-glutamic acid gold nanoclusters.

[0057] As an example, the silver nanoclusters include, but are not limited to, one or more of dimercaptohexane silver nanoclusters, 1-mercapto-2-propanone silver nanoclusters, undecanethiol silver nanoclusters, N-acetyl-L-cysteine silver nanoclusters, methionine silver nanoclusters, cysteine silver nanoclusters, N-acetyl-L-lysine silver nanoclusters, N-acetyl-L-glutamic acid silver nanoclusters.

[0058] As an example, the platinum nanoclusters include, but are not limited to, one or more of dimercaptohexane platinum nanoclusters, 1-mercapto-2-propanone platinum nanoclusters, undecanethiol platinum nanoclusters, N-acetyl-L-cysteine platinum nanoclusters, methionine platinum nanoclusters, cysteine platinum nanoclusters, N-acetyl-L-lysine platinum nanoclusters, N-acetyl-L-glutamic acid platinum nanoclusters.

[0059] In the metal nanoclusters, the molar ratio of the metal atoms to the ligands ranges from 1:(5 - 10), for example, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc. Within this range, the metal nanoclusters have appropriate sizes, which is beneficial for preparing an electron-functional layer with an appropriate thickness, and thus is beneficial for obtaining an electron-functional layer with excellent electron transport performance.

[0060] In some embodiments, the average particle size range of the metal nanoclusters is 1 - 10 nm.

[0061] The N-type inorganic nanoparticles include, but are not limited to, one or more of doped metal oxide particles, undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the undoped metal oxide particles include, but are not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5. The metal oxides in the doped metal oxide particles include, but are not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3, and the doping elements in the doped metal oxide particles include, but are not limited to, one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga. The IIB-VIA group semiconductor materials include, but are not limited to, one or more of ZnS, ZnSe, CdS. The IIIA-VA group semiconductor materials include, but are not limited to, one or more of InP, GaP. The IB-IIIA-VIA group semiconductor materials include, but are not limited to, one or more of CuInS, CuGaS.

[0062] In some embodiments, the average particle size range of the N-type inorganic nanoparticles is 5 - 8 nm.

[0063] In the composite material, the molar ratio of the N-type inorganic nanoparticles to the metal nanoclusters ranges from 1:(0.01 - 0.1), for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, etc. Within this molar ratio range, the electron transport efficiency of the composite material can be effectively improved.

[0064] In some embodiments, the conduction band energy level of the composite material is 3.6 - 4.0 eV, for example, 3.6 eV, 3.7 eV, 3.8 eV, 3.9 eV, 4.0 eV, etc.

[0065] In a second aspect, an embodiment of the present application further provides a thin film, and the thin film includes the composite material described above.

[0066] In a third aspect, please refer to Figure 1 , an embodiment of the present application further provides a method for preparing a thin film, including the following steps:

[0067] Step S11: Provide N-type inorganic nanoparticles, metal nanoclusters and a first solvent, mix them, and make the metal nanoclusters coordinate and adsorb on the N-type inorganic nanoparticles to form a composite material, obtaining a composite material dispersion;

[0068] Step S12: Set the composite material dispersion on a substrate and anneal it to obtain the thin film.

[0069] In the step S11:

[0070] The N-type inorganic nanoparticles and the metal nanoclusters are as described above and will not be elaborated here.

[0071] The molar ratio of the inorganic nanoparticles to the metal nanoclusters is 1:(0.01 - 0.1), for example, 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1, etc.

[0072] The first solvent includes but is not limited to alcohol solvents, and the alcohol solvents include but are not limited to one or more of methanol, ethanol, propanol, ethylene glycol, diethylene glycol, 2-propanediol, glycerol, 1,4-butanediol, 1,6-hexanediol.

[0073] The dosage of the solvent is not limited as long as it can fully disperse the N-type inorganic nanoparticles and the metal nanoclusters. In at least some embodiments, the concentration of the mixed solution is 20 - 50 mg / mL. Within this concentration range, the mixed solution has a good film-forming effect.

[0074] In some embodiments, after mixing, it further includes a step of ultrasonic dispersion. The power range of the ultrasonic wave is 20 - 40 KHz, and the time range is 10 min - 4 h. Within this range, it is beneficial for the metal nanoclusters to coordinate and adsorb on the N-type inorganic nanoparticles and is beneficial for obtaining a uniformly dispersed composite material dispersion.

[0075] In the step S12:

[0076] The substrate may be a substrate, a release film, or a transfer film known for film formation. 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, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0077] It can be understood that the substrate may also be a light-emitting device preform, such as a substrate including a cathode, or a stacked structure including a stacked anode, a hole functional layer, and a light-emitting layer.

[0078] The annealing temperature range is 80 to 120 °C, and the time range is 10 to 120 min. Within this temperature and time range, a good film-forming effect is achieved, which is beneficial for preparing a product with better crystallinity and excellent performance.

[0079] In a fourth aspect, please refer to Figures 2 - 3 , an embodiment of the present application provides a light-emitting device 100, including a first electrode 10 and a second electrode 30 disposed opposite to each other, and a light-emitting layer 40 located between the first electrode 10 and the second electrode 30. It further includes an electron transport layer 20, where the electron transport layer 20 is located between the light-emitting layer 40 and the first electrode 10 or between the light-emitting layer 40 and the second electrode 30. Among them, the material of the electron transport layer 20 includes the composite material, or the electron transport layer 20 is the thin film described above.

[0080] In some embodiments, the thickness range of the electron transport layer 20 is 20 to 60 nm.

[0081] It can be understood that the first electrode 10 is an anode and the second electrode 30 is a cathode; or the first electrode 10 is a cathode and the second electrode 30 is an anode.

[0082] For the light-emitting device 100 of the present application, the material of the electron transport layer is the composite material, which has good electron transport performance and stability, and can effectively improve the efficiency and lifespan of the light-emitting device 100.

[0083] Please refer to Figures 4 - 5 , in some embodiments, the light-emitting device 100 further includes a hole transport layer 50, and the hole transport layer 50 is located on a side of the light-emitting layer 40 away from the electron transport layer 20.

[0084] Please refer to Figures 6 - 7 , in some embodiments, the light-emitting device 100 further includes a hole injection layer 60, and the hole injection layer 60 is located on a side of the hole transport layer 50 away from the light-emitting layer 40.

[0085] The anode and the cathode are electrodes known in the art for light-emitting devices. For example, they can independently include but are not limited to doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The material of the doped metal oxide electrode can 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), aluminum-doped magnesium oxide (AMO), and cadmium-doped zinc oxide. The composite electrode is an electrode formed by laminating two or more layers of conductive materials, 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, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. Herein, " / " represents a laminated structure. For example, AZO / Ag / AZO represents a composite electrode including an AZO layer, an Ag layer, and an AZO layer laminated in sequence. The material of the elemental metal electrode can include but is not limited to one or more of Ag, Ni, Pt, Au, Ir, Cu, Mo, Al, Ca, Mg, and Ba. The alloy electrode includes but is not limited to Au:Mg alloy electrodes and Ag:Mg alloy electrodes.

[0086] In some embodiments, among the first electrode 10 and the second electrode 30, the electrode away from the electron transport layer 20 is an electrode with a relatively high work function. For example, it can include but is not limited to a doped metal oxide electrode with a relatively high work function, an elemental metal electrode with a relatively high work function, and a carbon nanotube electrode. The elemental metal electrode with a relatively high work function can be selected from but is not limited to Ni, Pt, Au, Ag, Ir, etc.

[0087] In some embodiments, among the first electrode 10 and the second electrode 30, the electrode close to the electron transport layer 20 is an electrode with a relatively low work function. For example, it can include but is not limited to an elemental metal electrode with a relatively low work function, a composite electrode with a relatively low work function, and an alloy electrode with a relatively low work function. The elemental metal electrode with a relatively low work function can be Ca, Ba, Al, Mg, etc. The composite electrode with a relatively low work function can be Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. The alloy electrode with a relatively low work function can be Au:Mg and Ag:Mg, etc.

[0088] The material of the light-emitting layer 40 may include, but is not limited to, one or more of organic light-emitting materials and quantum dot light-emitting materials.

[0089] The organic light-emitting materials may include, but are not limited to, one or more of CBP:Ir(mppy)3 (4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridine iridium(III)]), TCTX:Ir(mmpy) (4,4',4”-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridine iridium]), diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescence materials, TTA materials, TADF (thermally activated delayed) materials, polymers containing B-N covalent bonds, HLCT (hybrid local charge transfer excited state) materials, Exciplex (excimer complex) light-emitting materials, polyacetylene and its derivatives, poly(phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives.

[0090] The quantum dot light-emitting materials may include, but are not limited to, one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials.

[0091] 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 respectively 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.

[0092] As an example, the quantum dots of the core-shell structure may include, but are not limited to, one or more of 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.

[0093] The perovskite semiconductor material may include, but is not limited to, 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 a Cs + ion, 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+ and one or more of them, X is a halogen anion, including Cl - , Br - , I - and one or more of them. 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+ and one or more of them, X is a halogen anion, including Cl - , Br - , I - and one or more of them.

[0094] The material of the hole transport layer 50 may also be a material known in the art for hole transport layers. For example, it may be selected from, 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-ethylhexoxy)-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'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO, or one or more of them.

[0095] The material of the hole injection layer 60 may also be a material known in the art for hole injection layers, and may be selected from, but not limited to, 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, or one or more thereof.

[0096] The thicknesses of the first electrode 10 and the second electrode 30 are each independently 30 - 100 nm.

[0097] The thickness of the light - emitting layer 40 is 20 - 60 nm.

[0098] The thickness of the hole - transporting layer 50 is 20 - 60 nm.

[0099] The thickness of the hole injection layer 60 is 20 - 60 nm.

[0100] It can be understood that the light - emitting device 100 may further include some functional layers that are commonly 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, etc.

[0101] 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.

[0102] In some embodiments, the light - emitting device 100 further includes a substrate, and the substrate is disposed on the side of the first electrode 10 away from the light - emitting layer 40, or the substrate is disposed on the side of the second electrode 30 away from the light - emitting layer 40.

[0103] The substrate can 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, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0104] It can be understood that the light - emitting device 100 can be a normal - type light - emitting device or an inverted - type light - emitting device. The light - emitting device 100 can be a quantum - dot light - emitting device (QLED) or an organic light - emitting device (OLED).

[0105] The electron transport layer 20 of the light-emitting device 100 includes black titanium dioxide, thereby having a high luminous efficiency and a long lifespan.

[0106] In a fifth aspect, please refer to Figures 2 - 3 and Figure 8 , an embodiment of the present application further provides a method for manufacturing a light-emitting device, including the following steps:

[0107] Step S21: Provide a light-emitting device preform, where the light-emitting device preform includes a first electrode 10;

[0108] Step S22: Provide the composite material, and dispose the composite material on the light-emitting device preform to obtain an electron transport layer 20;

[0109] Step S23: Form a second electrode 30 on the electron transport layer 20 to obtain a light-emitting device 100.

[0110] The first electrode 10 is an anode and the second electrode 30 is a cathode; alternatively, the first electrode 10 is a cathode and the second electrode 30 is an anode.

[0111] Please refer to Figure 2 , in some embodiments, the light-emitting device preform further includes a light-emitting layer 40 disposed on the first electrode 10, and the composite material is disposed on the light-emitting layer 40.

[0112] Please refer to Figure 3 , in some other embodiments, forming the second electrode 30 on the electron transport layer 20 includes: sequentially forming a stacked light-emitting layer 40 and a second electrode 30 on the electron transport layer 20.

[0113] Please refer to Figure 4 , in some embodiments, the light-emitting device preform further includes a hole transport layer 50 and a light-emitting layer 40 that are sequentially stacked on the first electrode 10, and the composite material is disposed on the light-emitting layer 40.

[0114] Please refer to Figure 5 , in some other embodiments, forming the second electrode 30 on the electron transport layer 20 includes: sequentially forming a stacked light-emitting layer 40, a hole transport layer 50, and a second electrode 30 on the electron transport layer 20.

[0115] Please refer to Figure 6 , in some embodiments, the light-emitting device preform further includes a hole injection layer 60, a hole transport layer 50, and a light-emitting layer 40 that are sequentially stacked on the first electrode 10, and the composite material is disposed on the light-emitting layer 40.

[0116] Please refer to Figure 7, in some other embodiments, forming the second electrode 30 on the electron transport layer 20 includes: sequentially forming a stacked light-emitting layer 40, a hole transport layer 50, a hole injection layer 60, and the second electrode 30 on the electron transport layer 20.

[0117] The methods for forming the second electrode 30, the light-emitting layer 40, the hole transport layer 50, and the hole injection layer 60, and the method for disposing the composite material on the light-emitting device preform 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, electrolytic deposition, coprecipitation. 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 plating, 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, bar coating, etc.

[0118] It can be understood that when the light-emitting device 100 further includes 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, etc., the method for preparing the light-emitting device 100 may further include the step of preparing the above functional layers by conventional techniques in the art.

[0119] The method for preparing the light-emitting device described in the present application can prepare a light-emitting device 100 with good luminous efficiency and long lifespan.

[0120] In a sixth aspect, the present application also relates to a display device, which includes the light-emitting device 100.

[0121] The display device can be any electronic product with a display function. The electronic product includes but is not limited to a smart phone, a tablet computer, a laptop 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 can be, for example, a smart bracelet, a smart watch, a virtual reality (VR) helmet, etc.

[0122] 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.

[0123] Composite Material Embodiment 1

[0124] The composite material of this embodiment includes ZnO particles and N-acetyl-L-cysteine gold nanoclusters, and the molar ratio of ZnO nanoparticles to N-acetyl-L-cysteine gold nanoclusters is 1:0.05.

[0125] Composite Material Example 2

[0126] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, the molar ratio of ZnO nanoparticles to N-acetyl-L-cysteine gold nanoclusters is 1:0.01.

[0127] Composite Material Example 3

[0128] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, the molar ratio of ZnO nanoparticles to N-acetyl-L-cysteine gold nanoclusters is 1:0.1.

[0129] Composite Material Example 4

[0130] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, the molar ratio of ZnO nanoparticles to N-acetyl-L-cysteine gold nanoclusters is 1:0.001.

[0131] Composite Material Example 5

[0132] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, the molar ratio of ZnO nanoparticles to N-acetyl-L-cysteine gold nanoclusters is 1:0.02.

[0133] Composite Material Example 6

[0134] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, dithiohexane gold nanoclusters are used to replace the N-acetyl-L-cysteine gold nanoclusters in Example 1.

[0135] Composite Material Example 7

[0136] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, 1-mercapto-2-propanone gold nanoclusters are used to replace the N-acetyl-L-cysteine gold nanoclusters in Example 1.

[0137] Composite Material Example 8

[0138] This embodiment is basically the same as Composite Material Example 1, except that in this embodiment, N-acetyl-L-cysteine silver nanoclusters are used to replace the N-acetyl-L-cysteine gold nanoclusters in Example 1.

[0139] Composite Material Example 9

[0140] This example is basically the same as Composite Material Example 1, except that in this example, N-acetyl-L-cysteine platinum nanoclusters are used to replace the N-acetyl-L-cysteine gold nanoclusters in Example 1.

[0141] Composite Material Example 10

[0142] This example is basically the same as Composite Material Example 1, except that in this example, Mg-doped ZnO particles are used to replace the ZnO particles in Example 1, where the doping amount of Mg is 10%.

[0143] Composite Material Example 11

[0144] This example is basically the same as Composite Material Example 1, except that in this example, TiO2 particles are used to replace the ZnO particles in Example 1.

[0145] Composite Material Example 12

[0146] This example is basically the same as Composite Material Example 1, except that in this example, SnO2 particles are used to replace the ZnO particles in Example 1.

[0147] Composite Material Comparative Example 1

[0148] The material of this comparative example is the ZnO particles in Example 1.

[0149] Composite Material Comparative Example 2

[0150] The material of this comparative example is the Mg-doped ZnO particles in Example 10.

[0151] Composite Material Comparative Example 3

[0152] The material of this comparative example is the TiO2 particles in Example 11.

[0153] Composite Material Comparative Example 4

[0154] The material of this comparative example is the SnO2 particles in Example 12.

[0155] The conductivities and conduction band energy levels of the composite materials of Composite Material Examples 1 to 12 and the materials of Composite Material Comparative Examples 1 to 4 were respectively tested to obtain the conductivity and conduction band energy level of the materials. The test results are shown in Table 1.

[0156] Among them, the conductivity was tested by the four-probe resistance measurement method. The method for testing the conduction band energy level was as follows: The absorbance and wavelength data in ultraviolet-visible diffuse reflection measurement were plotted, and the absorption wavelength threshold λg (nm) was obtained by the intercept method. The band gap width was calculated using the formula Eg = 1240 / λg (eV), and then the conduction band energy level was calculated through the band gap width.

[0157] Table 1:

[0158] Conductivity (S / cm) Conduction band energy level (eV) Example 1 of composite material 2×10^-2 3.7 Example 2 of composite material 1.3×10^-2 3.9 Example 3 of composite material 1.8×10^-2 3.8 Example 4 of composite material 2×10^-3 4.0 Example 5 of composite material 7×10^-3 3.7 Example 6 of composite material 3×10^-2 3.8 Example 7 of composite material 1.2×10^-2 3.8 Example 8 of composite material 4×10^-2 3.7 Example 9 of composite material 3.5×10^-2 3.8 Example 10 of composite material 8×10^-3 3.6 Example 11 of composite material 3×10^-4 3.8 Example 12 of composite material 5×10^-3 4.3 Comparative Example 1 of composite material 1×10^-4 4.2 Comparative Example 2 of composite material 1×10^-4 4.0 Comparative Example 3 of composite material 1×10^-5 4.0 Comparative Example 4 of composite material 1×10^-3 4.5

[0159] As can be seen from Table 1:

[0160] Compared with the composite materials of Comparative Example 1 of the composite materials, the composite materials of Examples 1-9 of the composite materials have higher conductivity and lower conduction band energy levels. The reason may be that metal nanoclusters are connected to the ZnO in Examples 1-9 of the composite materials. Under the action of the metal nanoclusters, composite materials with good conductivity and lower conduction bands are obtained;

[0161] Compared with the composite materials of Comparative Example 2 of the composite materials, the composite materials of Example 10 of the composite materials have higher conductivity and lower conduction band energy levels. The reason may be that metal nanoclusters are connected to the Mg-doped ZnO in Example 10 of the composite materials. Under the action of the metal nanoclusters, composite materials with good conductivity and lower conduction bands are obtained;

[0162] Compared with the composite materials of Comparative Example 3 of the composite materials, the composite materials of Example 11 of the composite materials have higher conductivity and lower conduction band energy levels. The reason may be that metal nanoclusters are connected to the TiO2 particles in Example 11. Under the action of the metal nanoclusters, composite materials with good conductivity and lower conduction bands are obtained;

[0163] Compared with the composite materials of Comparative Example 4 of the composite materials, the composite materials of Example 12 of the composite materials have higher conductivity and lower conduction band energy levels. The reason may be that metal nanoclusters are connected to the SnO2 particles in Example 12. Under the action of the metal nanoclusters, composite materials with good conductivity and lower conduction bands are obtained.

[0164] Device Example 1

[0165] A glass substrate with an ITO first electrode 10 having a thickness of 100 nm was provided. The ITO conductive glass was cleaned with a cleaner to initially remove the stains on the surface. Subsequently, it was ultrasonically cleaned in deionized water, isopropanol, acetone, and deionized water for 20 min respectively to remove the impurities on the surface. Finally, it was dried with high-purity nitrogen;

[0166] In a glove box, a TFB material was spin-coated on the first electrode 10 and annealed at 200 °C for 30 min to obtain a hole transport layer 50 with a thickness of 40 nm;

[0167] A CdZnSe quantum dot material was spin-coated on the hole transport layer 50 and annealed at 100 °C for 30 min to obtain a light-emitting layer 40 with a thickness of 30 nm;

[0168] The composite material of Material Example 1 was dispersed in ethanol to obtain a dispersion, and the dispersion was spin-coated on the light-emitting layer 40 and annealed at 80 °C for 30 min to obtain an electron transport layer 20 with a thickness of 40 nm;

[0169] Ag was evaporated on the electron transport layer 20 to obtain a cathode with a thickness of 70 nm;

[0170] It was encapsulated in an environment where both the oxygen content and the water content were lower than 0.1 ppm to obtain a light-emitting device 100.

[0171] Device Examples 2-12

[0172] Device Examples 2-12 were the same as Device Example 1 respectively, except that the composite materials of Material Examples 2-12 were used respectively when preparing the electron transport layer 20 of Device Examples 2-12.

[0173] Device Comparative Examples 1-4

[0174] Device Comparative Examples 1-4 were the same as Device Example 1 respectively, except that the materials of Material Comparative Examples 1-4 were used respectively when preparing the electron transport layer 20 of Device Comparative Examples 1-4.

[0175] The light-emitting devices of Device Examples 1-12 and Device Comparative Examples 1-4 were respectively tested for external quantum efficiency EQE and lifetime T95@1000 nit. The test results are shown in Table 2.

[0176] Among them, the test method for the external quantum efficiency EQE was as follows: Using a FushiDa FPD optical property measurement device, an efficiency test system built by controlling a QE PRO spectrometer, a Keithley 2400, and a Keithley 6485 through LabView, parameters such as voltage, current, brightness, and emission spectrum were measured, and the external quantum efficiency EQE of the device was obtained through calculation. The specific calculation formula was as follows:

[0177]

[0178] 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 radiation process rate, and KNR is the non-radiation process rate.

[0179] The test method for the lifetime T95@1000nit is as follows: in CDA gas, under a constant current drive, the time it takes for the brightness of the device 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 the device aging at high brightness, and the lifetime at low brightness is obtained by fitting through the decay fitting formula. For example, the lifetime at 1000nits is denoted as T95@1000nits, and the calculation formula is:

[0180]

[0181] where T95 L is the lifetime at low brightness, generally taking the lifetime at 1000nits, T95 H is the lifetime at high brightness, that is, the measured lifetime, L H is the maximum brightness to which the device is accelerated, L L is generally 1000nits, A is the acceleration factor, taking 1.7. Among them, the constant current is 2mA.

[0182] The maximum external quantum efficiency EQE and the lifetime T95@1000nit are both carried out at room temperature, and the air humidity is 30 - 60%.

[0183] Table II:

[0184]

[0185]

[0186] As can be seen from Table II:

[0187] Compared with the light-emitting devices of device comparative example 1, the light-emitting devices of device examples 1 - 9 have higher external quantum efficiency and longer lifetime. The reason may be that the composite material in the electron transport layer of the light-emitting devices of device examples 1 - 9 includes inorganic nanoparticles and metal nanoclusters, and thus has better electron transport performance;

[0188] Compared with the light-emitting devices of device comparative example 2, the light-emitting devices of device example 10 have higher external quantum efficiency and longer lifetime. The reason may be that the composite material in the electron transport layer of the light-emitting devices of device example 10 includes inorganic nanoparticles and metal nanoclusters, and thus has better electron transport performance;

[0189] Compared with the light-emitting device of Device Comparative Example 3, the light-emitting device of Device Example 11 has a higher external quantum efficiency and a longer lifespan. The reason may be that the composite material in the electron transport layer of the light-emitting device of Device Example 11 includes inorganic nanoparticles and metal nanoclusters, thus having better electron transport performance.

[0190] Compared with the light-emitting device of Device Comparative Example 4, the light-emitting device of Device Example 12 has a higher external quantum efficiency and a longer lifespan. The reason may be that the composite material in the electron transport layer of the light-emitting device of Device Example 12 includes inorganic nanoparticles and metal nanoclusters, thus having better electron transport performance.

[0191] The technical solutions provided in the embodiments of the present application have been introduced in detail above. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is 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 manner and application scope. 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, The composite material includes N-type inorganic nanoparticles and metal nanoclusters.

2. The composite material according to claim 1, characterized in that, The metal nanoclusters include a metal core and ligands coordinatively bonded to the metal core. The metal core includes n metal atoms, where n is an integer from 1 to 1000.

3. The composite material according to claim 2, characterized in that, The metal nanoclusters are coordinatively bonded to the N-type inorganic nanoparticles; and / or The average particle size of the metal nanoclusters is 1 to 10 nm; and / or The average particle size of the N-type inorganic nanoparticles is 5 to 8 nm; and / or The conduction band energy level of the composite material is 3.6 to 4.0 eV; and / or The metal atoms include noble metal atoms, and the noble metal atoms include one or more of gold atoms, silver atoms, and platinum atoms; and / or The ligands include organic ligands and / or inorganic ligands. The organic ligands include one or more of thiol compounds, polymer polymers, and amino acids. Among them, the thiol compounds include one or more of dimercaptohexane, 1-mercapto-2-propanone, and undecanethiol. The amino acids include one or more of N-acetyl-L-cysteine, methionine, cysteine, N-acetyl-L-lysine, and N-acetyl-L-glutamic acid. The inorganic ligands include one or more of sulfides, phosphides, selenides, and tellurides. The sulfides include one or more of sodium sulfide, hydrogen sulfide, ammonium sulfide, and carbon disulfide. The phosphides include one or more of phosphine and sodium phosphide. The selenides include one or more of sodium selenide and cuprous selenide. The tellurides include one or more of cuprous telluride and zinc telluride.

4. The composite material according to claim 3, characterized in that, The metal nanoclusters include one or more of gold nanoclusters, silver nanoclusters, and platinum nanoclusters, where The gold nanoclusters include one or more of dimercaptohexane gold nanoclusters, 1-mercapto-2-propanone gold nanoclusters, undecanethiol gold nanoclusters, N-acetyl-L-cysteine gold nanoclusters, methionine gold nanoclusters, cysteine gold nanoclusters, N-acetyl-L-lysine gold nanoclusters, and N-acetyl-L-glutamic acid gold nanoclusters; and / or The silver nanoclusters include one or more of dimercaptohexane silver nanoclusters, 1-mercapto-2-propanone silver nanoclusters, undecanethiol silver nanoclusters, N-acetyl-L-cysteine silver nanoclusters, methionine silver nanoclusters, cysteine silver nanoclusters, N-acetyl-L-lysine silver nanoclusters, and N-acetyl-L-glutamic acid silver nanoclusters; and / or The platinum nanoclusters include one or more of dimercaptohexane platinum nanoclusters, 1-mercapto-2-propanone platinum nanoclusters, undecanethiol platinum nanoclusters, N-acetyl-L-cysteine platinum nanoclusters, methionine platinum nanoclusters, cysteine platinum nanoclusters, N-acetyl-L-lysine platinum nanoclusters, and N-acetyl-L-glutamic acid platinum nanoclusters.

5. The composite material according to claim 3, characterized in that, In the metal nanoclusters, the molar ratio range of the metal atoms to the ligands is 1:(5 to 10).

6. The composite material according to any one of claims 1 to 5, characterized in that, The N-type inorganic nanoparticles include one or more of doped metal oxide particles, undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the undoped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the doped metal oxide particles include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the doped metal oxide particles include one or several 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.

7. The composite material according to claim 6, characterized in that, The molar ratio range of the N-type inorganic nanoparticles to the metal nanoclusters is 1:(0.01-0.1).

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

9. A light-emitting device, comprising an anode and a cathode arranged opposite to each other, and a light-emitting layer located between the anode and the cathode, further comprising an electron transport layer, the electron transport layer being located between the light-emitting layer and the cathode, characterized in that, The material of the electron transport layer includes the composite material according to any one of claims 1 to 7.

10. The light-emitting device according to claim 9, characterized in that, The anode and the cathode each independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal single electrode, or an alloy electrode. The materials of the doped metal oxide particle electrodes include 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 electrodes include one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The materials of the metal single electrodes include one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba; and / or 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 includes 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, 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, an exciplex light-emitting material, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives;The quantum dot luminescent material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. 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 are each independently selected from 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 material includes 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, 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 light-emitting device further includes a hole transport layer on a side of the light-emitting layer away from the electron transport layer, and the material of the hole transport layer includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiro-NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, 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'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or The light-emitting device further includes a hole injection layer located on a side of the light-emitting layer away from the electron transport layer, and the material of the hole injection layer includes one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

11. A display device, characterized in that, Comprising the light-emitting device according to any one of claims 9 to 10.

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