Thin films and their preparation methods, light-emitting devices and display devices

Abstract

This application discloses a thin film and its preparation method, a light-emitting device, and a display device. The material of the thin film includes metal oxide nanoparticles, and multiple metal oxide nanoparticles are interlocked to form an interlocking body. The percentage w of the number of interlocking bodies to the total number of metal oxide nanoparticles in the thin film satisfies 0 ≤ w ≤ 25%. The thin film proposed in this application has a smaller number of interlocking bodies, thereby reducing the interparticle gaps caused by the interlocking bodies, improving the compactness of the thin film, and obtaining a thin film with better electrical properties.

Description

Technical Field

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

[0002] Metal oxide nanoparticles possess advantages such as wide bandgap, low work function, excellent carrier injection or transport, good stability, high transparency, and safety and non-toxicity, making them widely used in the semiconductor field. However, thin films based on metal oxide nanoparticles suffer from poor density. Summary of the Invention

[0003] In view of this, this application provides a thin film, a method for preparing the same, a light-emitting device, and a display device.

[0004] The embodiments of this application are implemented as follows:

[0005] In a first aspect, embodiments of this application provide a thin film, the material of which includes metal oxide nanoparticles, and a plurality of the metal oxide nanoparticles intercalate to form an intercalation body, wherein the percentage w of the number of the intercalation body to the total number of the metal oxide nanoparticles in the thin film satisfies 0 ≤ w ≤ 25%.

[0006] Secondly, embodiments of this application provide a method for preparing a thin film, comprising the following steps:

[0007] Provide a mixed solution containing a first compound and metal oxide nanoparticles;

[0008] The mixed solution is deposited to form a liquid film;

[0009] The liquid film is annealed to obtain a thin film;

[0010] The first compound includes a first metal carbide.

[0011] Thirdly, embodiments of this application provide a light-emitting device, including a stacked cathode, an electron transport layer, and an anode, wherein the electron transport layer includes the thin film described above, or a thin film prepared by the preparation method described above.

[0012] Fourthly, embodiments of this application provide a display device including the light-emitting device described above.

[0013] The thin film proposed in this application has a smaller number of intergranules, which can reduce the interparticle gaps caused by the intergranules, improve the compactness of the thin film, and obtain a light-emitting device with better electrical performance. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic flowchart of a method for preparing a thin film according to an embodiment of this application;

[0016] Figure 2 This is a schematic diagram of the structure of a light-emitting device provided in an embodiment of this application;

[0017] Figure 3 This is an electron microscope image of the thin film prepared in Comparative Example 1.

[0018] Figure 4 This is an electron microscope image of the thin film prepared in Thin Film Example 8;

[0019] Figure 5 This is a schematic diagram of metal oxide nanoparticles intercalating to form a chimera during high-temperature annealing.

[0020] Figure 6 This is a graph showing the change in the dispersion state of metal oxide nanoparticles in the film before and after annealing;

[0021] Reference numerals: Light-emitting device 100; Anode 10; Cathode 20; Light-emitting layer 30; Hole transport layer 40; Hole injection layer 50; Electron transport layer 60. Detailed Implementation

[0022] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and conciseness and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within that range. For example, it should be assumed that the description of a range from 1 to 6 specifically discloses subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0023] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0024] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0025] To passivate defects and adjust film activity, existing technologies often require high-temperature annealing after film fabrication. However, films based on inorganic nanoparticles, such as zinc oxide and tin oxide films prepared using metal oxide nanoparticles, are prone to problems such as decreased film density and deterioration of electrical properties during annealing. The inventors have discovered that the main reason for these problems is that during annealing, nanoparticles may undergo regrowth, releasing stress. This process involves deformation or relative movement, ultimately leading to the intercalation of previously tightly packed adjacent grains. Figure 5 and Figure 6 As shown. When grain intercalation occurs, the grain arrangement is disrupted, the crystal lattice is distorted, the crystal structure is destroyed, and dislocations (defects) appear, thus affecting the electrical properties of the thin film. Simultaneously, it also makes the originally dense thin film prone to developing many pores (such as those left by grain displacement) due to grain displacement. Figure 3 Problems such as decreased lifespan.

[0026] In view of this, this application proposes a thin film, wherein the material of the thin film includes metal oxide nanoparticles, and an aggregate formed by the mutual intercalation of multiple metal oxide nanoparticles is a chimera, wherein the percentage w of the number of chimeras to the total number of metal oxide nanoparticles in the thin film satisfies 0 ≤ w ≤ 25%.

[0027] The thin film proposed in this application has a smaller number of intergranules, which can reduce the interparticle gaps caused by the intergranules, improve the compactness of the thin film, and obtain a thin film with better electrical properties.

[0028] Among them, chimera refers to, for example, Figure 5 and Figure 6 The image shows an aggregate formed by the intercalation of two or more nanoparticles. In some embodiments, the average particle size of the metal oxide nanoparticles in the film can be 2–5 nm; for example, 2 nm, 3 nm, 4 nm, 5 nm, and values ​​between any two of the above. The average particle size of the chimera is greater than or equal to 10 nm; for example, 10 nm, 12 nm, 13 nm, 15 nm, 18 nm, 20 nm, etc. In this application, the average particle size can be understood as the average particle size of a group of nanoparticles, which can be detected by transmission electron microscopy (TEM). It should be noted that the particle size of the chimera can be understood as the average of the minimum diameters of the chimera projections displayed when projected using TEM.

[0029] The thin film proposed in this application has a superior microstructure and good density. Its porosity is 10-30%; for example, 10%, 12%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, and any two of the above values. The porosity can be detected by the BET method.

[0030] The metal oxide nanoparticles may include one or more of undoped metal oxides and doped metal oxides. Specifically, the undoped metal oxides may include, but are not limited to, one or more of ZnO, SnO2, and TiO2; the doped metal oxides are oxides doped with a dopant element, wherein the oxides may include, but are not limited to, one or more of ZnO, SnO2, and TiO2, and the dopant element may include, but is not limited to, one or more of Al, Mg, Li, In, and Ga.

[0031] The thin film of this application can be used to fabricate the electron transport layer 60 of the light-emitting device 100, and the light-emitting device 100 made based on the thin film is less prone to leakage and has better lifespan and luminous efficiency.

[0032] In some embodiments, the molar percentage of the dopant element in the doped metal oxide is 0.01 to 20%; for example, it can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, or any value between any two of the above.

[0033] In some embodiments, the material of the film further includes a first compound comprising a metal carbide. In other embodiments, the material of the film further includes a first compound comprising a thickener. In still other embodiments, the material of the film further includes a first compound comprising a metal carbide and a thickener.

[0034] In some specific embodiments, the metal carbide includes one or more of vanadium carbide, trichromium carbide, tantalum carbide, niobium carbide, titanium carbide, molybdenum carbide, zirconium carbide, and hafnium carbide.

[0035] Furthermore, in the thin film, the mass ratio of the metal carbide to the metal oxide nanoparticles is 6 to 23:100; for example, it can be 6:100, 10:100, 15:100, 18:100, 20:100, 23:100, or any value between any two of the above.

[0036] In some specific embodiments, the thickener may include, but is not limited to, one or more of C10-C18 alcohols, C10-C18 acids, polymers, amine oxides, fatty alcohol polyoxyethylene ether sulfates, and ethyl cellulose. Specifically, the C10-C18 alcohols may include, but are not limited to, one or more of terpineol, lauryl alcohol, and stearyl alcohol; the C10-C18 acids include, but are not limited to, one or more of stearic acid, linolenic acid, and linoleic acid; the polymers may include, but are not limited to, one or more of polyurethane, polyacrylate, polyethylene glycol, and polyoxyethylene; and the amine oxides may include, but are not limited to, one or more of myristotinamide oxide and cocoaminopropylamine oxide.

[0037] Furthermore, in some embodiments, the mass ratio of the thickener to the metal oxide nanoparticles in the film is 6 to 23:100; for example, it can be 6:100, 10:100, 15:100, 18:100, 20:100, 23:100, and any two of the above values.

[0038] This application also proposes a method for preparing a thin film, which can produce the thin film described above. Please refer to [link / reference]. Figure 1 The preparation method includes the following steps:

[0039] Step S10: Provide a mixed solution containing a first compound and metal oxide nanoparticles, wherein the first compound includes a first metal carbide;

[0040] Step S20: Deposit the mixed solution and perform annealing treatment to obtain a thin film.

[0041] The preparation method provided in this application involves adding a first metal carbide to a mixed solution before annealing. The metal carbide can reduce the migration rate of grain boundaries, inhibit grain regrowth, and improve the intercalation problem during annealing. Simultaneously, it can form stable compounds at grain boundaries, enhancing grain boundary strength, improving the material's resistance to stress deformation, and further suppressing intercalation.

[0042] The films prepared by this method contain fewer intercalators; in some embodiments, the percentage of intercalators in the films is 0-25%. The films prepared by this method exhibit good compactness and low porosity; in some embodiments, the porosity of the films is 10-30%.

[0043] The metal oxide nanoparticles may include one or more of undoped metal oxides and doped metal oxides. Specifically, the undoped metal oxides may include, but are not limited to, one or more of ZnO, SnO2, and TiO2; the doped metal oxides are oxides doped with a dopant element, wherein the oxides may include, but are not limited to, one or more of ZnO, SnO2, and TiO2, and the dopant element may include, but is not limited to, one or more of Al, Mg, Li, In, and Ga. When the metal oxide nanoparticles include doped metal oxides, the molar percentage of the dopant element in the doped metal oxide is 0.01% to 20%; for example, it may be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 5%, 8%, 10%, 13%, 15%, 18%, 20%, or any value between any two of the above.

[0044] The first metal carbide may include, but is not limited to, one or more of vanadium carbide, trichromium carbide, tantalum carbide, niobium carbide, titanium carbide, molybdenum carbide, zirconium carbide, and hafnium carbide. Using the above-mentioned metal carbides can effectively suppress regrowth, improve intercalation problems, and significantly reduce the percentage of intercalators in the prepared film.

[0045] The amount of the first metal carbide can be based on the amount of metal oxide nanoparticles. For example, in some embodiments, the mass ratio of the first metal carbide to the metal oxide nanoparticles is 6 to 23:100; for example, it can be 6:100, 10:100, 15:100, 18:100, 20:100, 23:100, or any two of the above values. Controlling the feed ratio within this range can improve the intercalation problem while ensuring that the film has better electrical properties.

[0046] In some embodiments, the first compound may further include a thickener. The thickener can increase the viscosity of the mixed solution, so that the formed film is a liquid film with a certain degree of fluidity. The grains in the liquid film are fluid and not closely packed together. In this way, sufficient growth space can be reserved during post-annealing, so as to improve the interlocking problem while achieving close grain packing.

[0047] The thickener may include, but is not limited to, one or more of C10-C18 alcohols, C10-C18 acids, polymers, amine oxides, fatty alcohol polyoxyethylene ether sulfates, and ethyl cellulose. Specifically, the C10-C18 alcohols may include, but are not limited to, one or more of terpineol, lauryl alcohol, and stearyl alcohol; the C10-C18 acids include, but are not limited to, one or more of stearic acid, linolenic acid, and linoleic acid; the polymers may include, but are not limited to, one or more of polyurethane, polyacrylate, polyethylene glycol, and polyoxyethylene; and the amine oxides may include, but are not limited to, one or more of myristotinamide oxide and cocoaminopropylamine oxide. Using the above-mentioned thickeners allows for compatibility with the mixing system, resulting in a mixed solution with good mixing effect, which helps to ensure film-forming effect while exerting the thickener's function.

[0048] The amount of thickener added can be based on the amount of metal oxide nanoparticles. For example, in some embodiments, the mass ratio of the thickener to the metal oxide nanoparticles is 6 to 23:100; for example, it can be 6:100, 10:100, 15:100, 18:100, 20:100, 23:100, or any two of the above values. Controlling the addition ratio within this range can improve the intercalation problem while ensuring that the film has better electrical properties.

[0049] In addition to the first compound and the metal oxide nanoparticles, the mixed solution also includes a solvent to provide a better dispersion environment, allowing the first compound and the metal oxide nanoparticles to be uniformly dispersed in the mixed system. The solvent may include C1-C8 alcohols, for example, including but not limited to one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol.

[0050] To ensure that the nanoparticles and the first compound are dispersed at a better concentration in the mixed system to prepare a film with better density, in some embodiments, the concentration of the metal oxide nanoparticles in the mixed solution is 10-60 mg / mL; for example, it can be 10 mg / mL, 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, or any value between any two of the above.

[0051] In step S10, the metal oxide nanoparticles can be mixed with the first compound and a solvent to obtain a mixed solution. Alternatively, the mixed solution can be prepared in the following manner:

[0052] A precursor solution containing a metal salt and an alkali are provided; the precursor solution and the alkali are mixed and reacted to obtain a nanoparticle solution containing metal oxide nanoparticles; the nanoparticle solution is mixed with the first compound to obtain the mixed solution.

[0053] By synthesizing metal oxide nanoparticles and then adding the first compound to the prepared metal oxide nanoparticle solution for mixing, the size and dispersion of the metal oxide nanoparticles can be better controlled, resulting in small-sized nanoparticles that can be well dispersed in the solution environment. This also allows the first compound and the metal oxide nanoparticles to be well dispersed, avoiding agglomeration.

[0054] The metal salt may include, but is not limited to, a first metal salt or a mixture of a first metal salt and a second metal salt. The first metal salt includes one or more of zinc, tin, and titanium salts; the second metal salt includes one or more of aluminum, magnesium, lithium, indium, and gallium salts. It is understood that when the metal oxide nanoparticles to be prepared are undoped metal oxides, the metal salt is the first metal salt; when the metal oxide nanoparticles to be prepared are doped metal oxides, the metal salt is a mixture of the first and second metal salts, wherein the second metal salt is introduced as a dopant element source.

[0055] The alkali may include, but is not limited to, one or more of alkali metal oxides, alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal bicarbonates; for example, sodium hydroxide, potassium hydroxide, sodium bicarbonate, sodium carbonate, etc.

[0056] When step S10 is performed as described above, the amount of the first metal carbide and the thickener added can be based on the amount of metal salt added. For example, in some embodiments, the mass ratio of the first metal carbide to the metal salt is 3 to 10:100; such as 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, and any two of the above values. The mass ratio of the thickener to the metal salt is 3 to 10:100; such as 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, and any two of the above values.

[0057] To further improve the film formation effect, reduce intercalation, and improve leakage current, the precursor solution may also include a second metal carbide; that is, a metal carbide is added during the synthesis of metal oxide nanoparticles to adjust the size of the obtained metal oxide nanoparticles, further reduce the gaps between particles in the film, and improve the compactness of the film after formation.

[0058] The second metal carbide may include, but is not limited to, one or more of vanadium carbide, trichromium carbide, tantalum carbide, niobium carbide, titanium carbide, molybdenum carbide, zirconium carbide, and hafnium carbide; the first metal carbide and the second metal carbide may be the same or different.

[0059] To avoid interfering with the carrier transport performance of the thin film itself, in some embodiments, the total mass of the first metal carbide and the second metal carbide can be controlled. For example, the mass ratio of the total mass of the first metal carbide and the second metal carbide to the metal salt can be controlled to be 3 to 10:100; such as 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, and any two of the above values.

[0060] Returning to step S20, the process parameters for the annealing treatment can be improved to further mitigate the interlocking problem:

[0061] The annealing temperature can be between 80 and 120°C; for example, it can be 80°C, 90°C, 100°C, 110°C, 120°C, or any two of the above values. Controlling the annealing temperature within this range can, on the one hand, passivate surface defects of the thin film, adjust the film activity, and give the film better electrical properties, avoiding quenching of the quantum dots in the light-emitting layer 30 when using this thin film to prepare the light-emitting device 100, thereby improving the light-emitting performance and lifetime of the device. On the other hand, it can, to a certain extent, regulate the regrowth process and improve the intercalation problem.

[0062] The annealing time can be 10–20 min; for example, it can be 10 min, 12 min, 13 min, 15 min, 18 min, 20 min, or any value between two of the above. Controlling the annealing time within this range can ensure the annealing effect while controlling the excessive growth of nanoparticles and inhibiting intercalation.

[0063] This application also proposes a light-emitting device 100, such as a quantum dot light-emitting diode, an organic light-emitting diode, etc. Please refer to... Figure 2 The light-emitting device 100 includes a stacked cathode 20, an electron transport layer 60, and an anode 10. The electron transport layer 60 includes the thin film described above or the thin film prepared by the preparation method described above.

[0064] The electron transport layer 60 prepared by the above-mentioned thin film can improve the leakage problem, so that the light-emitting device 100 has a lower leakage rate, higher light-emitting performance and longer service life.

[0065] In addition, in some embodiments, the light-emitting device 100 may further include a light-emitting layer 30, which is located between the electron transport layer 60 and the anode 10. The thickness of the light-emitting layer 30 is 8 nm to 50 nm; for example, it can be 8 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, or any two of the above values.

[0066] The material of the light-emitting layer 30 may include organic light-emitting materials or quantum dots.

[0067] The organic light-emitting material is a material known in the art for use in organic light-emitting layers. For example, it may be selected from, but is not limited to, one or more of diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent material emitting blue light, TTPA fluorescent material emitting green light, TBRb fluorescent material emitting orange light, and DBP fluorescent material emitting red light.

[0068] The quantum dot is a quantum dot known in the art for use in quantum dot emitting layers, such as red quantum dots, green quantum dots, and blue quantum dots. The quantum dot can be selected from, but is not limited to, single-structure quantum dots, core-shell quantum dots, and perovskite semiconductor materials, wherein the shell of the core-shell quantum dot comprises one or more layers; the material of the single-structure quantum dot, the core material of the core-shell quantum dot, and the shell material of the core-shell quantum dot respectively include one or more of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds; the group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, and CdST. e, 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 SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, S One or more of nSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and GaAlNP. One or more of the following compounds: 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 general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs.+ Ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, where X is a halide anion selected from 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 selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2 + Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, where X is a halide anion selected from Cl... - ,Br - I - One or more of them.

[0069] As an example, the quantum dots with core-shell structure can be selected from but not limited to one or more of CdZnSe / CdZnSe / ZnSe / CdZnS / ZnS, CdZnSe / CdZnSe / CdZnS / ZnS CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS and InP / ZnSe / ZnS. It should be noted that for the materials of the aforementioned single-structure quantum dots, or the core materials of the core-shell structure quantum dots, or the shell materials of the core-shell structure quantum dots, the provided chemical formulas only indicate the elemental composition and do not indicate the content of each element. For example, CdZnSe only indicates that it is composed of three elements, Cd, Zn, and Se. If the content of each element is to be represented, it corresponds to Cd x Zn 1-x Se, 0 < x < 1. It can be understood that the core materials and the materials of each shell layer of the core-shell structure quantum dots are expressed by connecting with " / ", and the order from left to right is the types of materials of the quantum dots from the inside to the outside: core material / first shell layer material / Nth shell layer material, where N is an integer greater than or equal to 1. For example, CdSe / CdZnSeS / ZnS represents a core-shell structure quantum dot with two shell layers, whose core material is CdSe, the material of the first shell layer coated on the core is CdZnSeS, and the material of the second shell layer coated outside the first shell layer is ZnS.

[0070] The anode 10 and the cathode 20 each independently include a doped metal oxide particle electrode, a metal-metal oxide composite electrode, a graphene electrode, a carbon nanotube electrode, a metal electrode, or an alloy electrode. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, and ITO / Ag. The electrode materials are selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba, including ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, and ZnS / Al / ZnS. The " / " indicates a stacked structure; for example, the composite electrode AZO / Ag / AZO represents a three-layered composite electrode consisting of an AZO layer, an Ag layer, and an AZO layer. The thickness of the anode 10 can be 100–120 nm, and the thickness of the cathode 20 can be 100–120 nm.

[0071] In some embodiments, the light-emitting device 100 may further include a hole functional layer located between the electron transport layer 60 and the anode 10. When the light-emitting device 100 also includes an emitting layer 30, the hole functional layer is located between the emitting layer 30 and the anode 10. The hole functional layer includes one or both of a hole injection layer 50 and a hole transport layer 40. When the hole functional layer includes both a hole injection layer 50 and a hole transport layer 40, the hole injection layer 50 is located between the hole transport layer 40 and the anode 10. In one embodiment, the light-emitting device 100 may include, from bottom to top, an anode 10, a hole injection layer 50, a hole transport layer 40, an emitting layer 30, an electron transport layer 60, and a cathode 20, stacked sequentially. In another embodiment, the light-emitting device 100 may include, from bottom to top, a cathode 20, an electron transport layer 60, an emitting layer 30, a hole transport layer 40, a hole injection layer 50, and an anode 10, stacked sequentially.

[0072] The material of the hole transport layer 40 can be selected from organic materials with hole transport capabilities, including but not limited to 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), and N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NP). D), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (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-3-methylphenyl-N-phenylamino) The following are included in the list of poly(p-)phenylene oxide (m-MTDATA), poly(p-)phenylene vinylidene (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylidene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylidene] (MOMO-PPV), 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS, poly(N-vinylcarbazole) (PVK), polymethacrylate, poly(9,9-octylfluorene), N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine (NPB), spiroNPB, doped graphene, undoped graphene, and one or more transition metal oxides, wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO. In some embodiments, the thickness of the hole transport layer 40 can be 20 to 60 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any value between any two of the above.

[0073] The hole injection layer 50 is made of materials known in the art that have hole injection capabilities, including but not limited to poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethylethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HATCN), copper polyester carbonate (CuPc), transition metal oxides, and metal chalcogenides; wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO; and the metal chalcogenides include one or more of MoS2, MoSe2, WS3, WSe3, and CuS. In some embodiments, the thickness of the hole injection layer 50 can be 20 to 60 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, or any value between any two of the above.

[0074] In some embodiments, the light-emitting device may further include an electron injection layer disposed between the electron transport layer 60 and the cathode 20. The electron injection material may be a material known in the art for use in electron injection layers, such as at least one selected from, but not limited to, LiF, MgP, MgF2, Al2O3, Ga2O3, LiF / Yb, ZnO, Cs2CO3, RbBr, and Rb2CO3.

[0075] It is understood that the light-emitting device 100 may also be provided with some functional layers that are conventionally used in the light-emitting device 100 and help to improve the device performance, such as electron blocking layer, hole blocking layer, interface modification layer, etc.

[0076] It is understood that the materials of each layer of the light-emitting device 100 can be adjusted according to the light-emitting requirements of the light-emitting device 100.

[0077] It is understood that the light-emitting device 100 can be an upright device or an inverted device.

[0078] This application also proposes a method for fabricating a light-emitting device 100, which can fabricate the aforementioned light-emitting device 100. Specifically, the light-emitting device 100 can be fabricated by sequentially fabricating each film layer according to a preset film layer order. For example, when the structure of the light-emitting device 100 to be fabricated is an anode 10, a hole injection layer 50, a hole transport layer 40, a light-emitting layer 30, an electron transport layer 60, and a cathode 20 stacked sequentially from bottom to top, the anode 10 can be fabricated on a substrate, then a hole injection layer 50 can be deposited on the anode 10 using a hole injection material, a hole transport layer 40 can be deposited on the hole injection layer 50 using a hole transport material, and a light-emitting layer 30 can be deposited on the hole transport layer 40 using an organic light-emitting material or quantum dots. Further, referring to the above-mentioned film fabrication method, an electron transport layer 60 can be fabricated on the light-emitting layer 30, and finally, a cathode 20 can be fabricated on the electron transport layer 60.

[0079] It should be noted that the methods for forming the light-emitting layer 30 and other functional layers, such as the hole injection layer 50, the hole transport layer 40, and the electron transport layer 60, can be chemical or physical methods. Chemical methods can include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods can include physical deposition or solution processing. Physical deposition methods include thermal evaporation deposition (CVD), electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition (PVD), atomic layer deposition, and pulsed laser deposition. Solution processing methods include spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating. Those skilled in the art can prepare the various film layers of the light-emitting device 100 of this application embodiment according to the known methods for preparing light-emitting devices 100, which will not be elaborated here.

[0080] Thirdly, this application also relates to a display device, which includes the light-emitting device 100 provided in this application. The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0081] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0082] Thin Film Example 1

[0083] Step 1: Weigh out zinc acetate and lithium hydroxide according to a molar ratio of metal salt (zinc acetate) to alkali (lithium hydroxide) of 1:1.1. Mix zinc acetate and anhydrous ethanol, and heat under reflux at 95°C for 30 min to obtain an alcoholic solution of zinc acetate. After the alcoholic solution of zinc acetate cools to room temperature, add lithium hydroxide, sonicate for 1 h to completely dissolve the lithium hydroxide, and then carry out a hydrolysis reaction at 60°C to obtain a mixed system containing zinc oxide nanoparticles. Add ethyl acetate to the mixed system to precipitate the precipitate, separate the precipitate, and disperse it in ethanol to obtain an ethanolic solution of zinc oxide nanoparticles, wherein the concentration of zinc oxide nanoparticles is approximately 30 mg / mL, and the average particle size of the zinc oxide nanoparticles is approximately 5 nm.

[0084] Step 2: Add vanadium carbide to the ethanol solution of zinc oxide nanoparticles according to the mass ratio of the first metal carbide (vanadium carbide) to the metal salt (zinc acetate) of 5:100 to obtain a mixed solution.

[0085] Step 3: Provide a glass substrate, spin-coat the mixed solution onto the glass substrate at 3000 rpm for 30 seconds, and then heat at 100°C for 15 minutes to obtain a thin film with a thickness of approximately 35 nm.

[0086] Thin Film Example 2

[0087] This embodiment is basically the same as thin film embodiment 1, except that in step 1 of this embodiment, when mixing the alcoholic solution of zinc acetate and lithium hydroxide, a second metal carbide (vanadium carbide) is added simultaneously, and the mass ratio of vanadium carbide to zinc acetate is 3:100. Accordingly, the average particle size of the obtained zinc oxide nanoparticles is approximately 3 nm.

[0088] Thin Film Example 3

[0089] This embodiment is basically the same as thin film embodiment 2, except that in step 2 of this embodiment, the mass ratio of the first metal carbide to the metal salt is 3:100.

[0090] Thin Film Example 4

[0091] This embodiment is basically the same as thin film embodiment 2, except that in step 2 of this embodiment, the mass ratio of the first metal carbide to the metal salt is 10:100.

[0092] Thin Film Example 5

[0093] This embodiment is basically the same as thin film embodiment 2, except that in step 2 of this embodiment, the mass ratio of the first metal carbide to the metal salt is 11:100.

[0094] Thin Film Example 6

[0095] This embodiment is basically the same as thin film embodiment 2, except that in step 2 of this embodiment, the first metal carbide is replaced with zirconium carbide.

[0096] Thin Film Example 7

[0097] This embodiment is basically the same as thin film embodiment 2, except that in step 2 of this embodiment, the first metal carbide is replaced with molybdenum carbide.

[0098] Thin Film Example 8

[0099] This embodiment is basically the same as thin film embodiment 2, except that in step 2 of this embodiment, a thickener (lauryl alcohol) is added to the mixed solution. Accordingly, step 2 is changed to:

[0100] A mixed solution was obtained by adding vanadium carbide and lauryl alcohol to an ethanol solution of zinc oxide nanoparticles, with a mass ratio of 5:100 for the first metal carbide (vanadium carbide) to the metal salt (zinc acetate) and a mass ratio of 5:100 for the thickener (lauryl alcohol) to the metal salt (zinc acetate).

[0101] Thin Film Example 9

[0102] This embodiment is basically the same as film embodiment 8, except that in step 2 of this embodiment, the thickener is replaced with polyacrylate.

[0103] Thin Film Example 10

[0104] This embodiment is basically the same as thin film embodiment 8, except that in step 3 of this embodiment, the annealing temperature is 80°C.

[0105] Thin Film Example 11

[0106] This embodiment is basically the same as thin film embodiment 8, except that in step 3 of this embodiment, the annealing temperature is 120°C.

[0107] Thin Film Example 12

[0108] This embodiment is basically the same as thin film embodiment 8, except that in step 3 of this embodiment, the annealing temperature is 130°C.

[0109] Thin Film Example 13

[0110] This embodiment is basically the same as thin film embodiment 8, except that the annealing time in step 3 of this embodiment is 10 minutes.

[0111] Thin Film Example 14

[0112] This embodiment is basically the same as thin film embodiment 8, except that the annealing time in step 3 of this embodiment is 20 minutes.

[0113] Thin Film Example 15

[0114] This embodiment is basically the same as thin film embodiment 8, except that the annealing time in step 3 of this embodiment is 25 minutes.

[0115] Thin Film Example 16

[0116] This embodiment is basically the same as thin film embodiment 8, except that in step 2 of this embodiment, the metal salt is replaced with tin acetate, and the resulting nanoparticles are tin oxide nanoparticles.

[0117] Thin Film Comparative Example 1

[0118] This comparative example is basically the same as that of Thin Film Example 1, except that the first metal carbide is not added in this comparative example. Accordingly, step 2 is omitted, and the preparation method is changed to:

[0119] An ethanol solution containing zinc oxide nanoparticles is provided, wherein the average particle size of the zinc oxide nanoparticles is approximately 5 nm and the concentration of the zinc oxide nanoparticles is approximately 30 mg / mL.

[0120] An ethanol solution of zinc oxide nanoparticles was spin-coated onto a glass substrate at 3000 rpm for 30 seconds, followed by heating at 100°C for 15 minutes to obtain a thin film with a thickness of approximately 35 nm.

[0121] Thin Film Comparative Example 2

[0122] This comparative example is basically the same as that of thin film example 16, except that the first metal carbide, the second metal carbide and the thickener are not added in this comparative example. Accordingly, step 2 is omitted. The solution of nickel oxide nanoparticles is spin-coated onto a glass substrate at a speed of 3000 rpm for 30 s, and then heated at 100°C for 15 min to obtain a thin film with a thickness of about 35 nm.

[0123] Device Example 1

[0124] This embodiment provides a QLED device with a structure of ITO (110nm) / PEDOT:PSS (50nm) / TFB (40nm) / QD (25nm) / ETL (35nm, ZnO) / Al (100nm). The fabrication method is as follows:

[0125] Step S1: Spin-coat an aqueous solution of PEDOT:PSS onto the ITO surface at 5000 rpm for 30 seconds, then heat on a 150°C hot plate for 15 minutes to obtain a hole injection layer with a thickness of 50 nm.

[0126] Step S2: Spin-coat a chlorobenzene solution of TFB (concentration of 8 mg / mL) onto the hole injection layer at 3000 rpm for 30 s, and then heat it on a 120°C heating plate for 10 min to obtain a hole transport layer with a thickness of 40 nm.

[0127] Step S3: Spin-coat a hexane solution of CdSe / ZnS green quantum dots onto the hole transport layer at 2000 rpm for 30 s, and then heat it on a 100°C heating plate for 10 min to obtain a light-emitting layer with a thickness of 25 nm.

[0128] Step S4: Following the method of Thin Film Example 1, a thin film is prepared on the light-emitting layer. Accordingly, the glass substrate in Thin Film Example 1 is replaced with the light-emitting layer to obtain an electron transport layer with a thickness of 35 nm.

[0129] Step S5: Through thermal evaporation, the vacuum level is no higher than 3x10. -4 Pa, Ag vapor deposition, speed is A positive quantum dot light-emitting diode was obtained by packaging a time of 200s and a thickness of 20nm.

[0130] Device Examples 2 to 16

[0131] The scheme of Example n is basically the same as that of Example 1, except that in step S4 of Example n, the corresponding electron transport layer is prepared by referring to the method of thin film Example n, and n is any integer from 2 to 16.

[0132] Device Comparison Example 1

[0133] This comparative example scheme is basically the same as that of device example 1, except that in step S4 of this comparative example 1, the corresponding electron transport layer is prepared by referring to the method of thin film comparative example 1.

[0134] Device Comparison Example 2

[0135] This comparative example scheme is basically the same as that of device example 16, except that in step S4 of this comparative example 1, the corresponding electron transport layer is prepared by referring to the method of thin film comparative example 2.

[0136] Experimental Example

[0137] (a) The thin film prepared in Thin Film Example 8 and the thin film prepared in Thin Film Comparative Example 1 were observed by transmission electron microscopy (TEM), and the results are as follows. Figure 3 and Figure 4 As shown.

[0138] contrast Figure 3 and Figure 4It can be seen that the film prepared in Example 8 has better density, with relatively fewer and smaller pores. This demonstrates that the method of this application helps to improve the density of the film.

[0139] (ii) The films prepared in the thin film examples and comparative examples were subjected to the following tests, and the results are shown in Table 1.

[0140] The detection method is as follows:

[0141] (1) Percentage of chimeras: The thin film was observed using a transmission electron microscope (TEM) to assess the percentage of chimeras (with an average particle size greater than or equal to 10 nm) in the detection image relative to the total number of non-chimera metal oxide nanoparticles and chimeras.

[0142] (2) Porosity: The porosity of the thin film was detected by the BET method. The specific BET test method for porosity is as follows: the thin film sample is pretreated at 80-130℃ (not higher than the processing temperature when the thin film is prepared for the device) and 10Pa for 10min to remove the originally adsorbed gas molecules; then the adsorption-desorption test is performed in the range of 0.01-500kPa, and the test system directly reads the required data.

[0143] (3) Electron mobility: Measured using conventional carrier mobility testing methods. The carrier mobility testing method involves: measuring the current density-voltage curves of the thin-film semiconductor devices (single carrier transport thin-film devices, EODs) of the test examples and comparative examples, obtaining the space charge confinement current (SCLC) region in the current density-voltage curves, and then calculating the electron mobility using the formula J = (9 / 8)ε. r ε0μ e V 2 / d 3 Calculate the electron mobility, where J represents the current density in mA / cm². -2 ;ε r ε₀ represents the relative permittivity, and μ represents the vacuum permittivity. e Electron / hole mobility is expressed in cm. 2 V -1 s -1 V represents the driving voltage, with units of V; d represents the film thickness, with units of m.

[0144] The structure of EOD is anode / quantum dot light-emitting layer / electron transport layer / cathode, and the structure of HOD is anode / hole transport layer / quantum dot light-emitting layer / cathode. The electron transport layer in EOD adopts the thin film of Examples 1 to 16 or Comparative Examples 1 to 2, and the other film materials are the same as those in Device Example 1.

[0145] Table 1

[0146]

[0147]

[0148] As can be seen from the table above:

[0149] Thin film examples 1 to 15 have lower intercalation content and porosity than thin film comparative example 1, and higher electron mobility than thin film comparative example 1. Meanwhile, thin film example 16 also has lower intercalation content and porosity than thin film comparative example 2, and higher electron mobility than thin film comparative example 2. This shows that the thin film prepared by the method of this application can improve the intercalation problem that occurs during annealing and improve the compactness and electrical properties of the thin film.

[0150] (III) Performance tests were conducted on the QLED devices fabricated using the above-mentioned device embodiments and device comparison examples. The results are shown in Table 2. The testing methods are as follows:

[0151] (1) External quantum dot efficiency (EQE):

[0152] The ratio of electron-hole pairs injected into a quantum dot to emitted photons, expressed as a percentage (%), is an important parameter for evaluating the quality of electroluminescent devices. It can be measured using an EQE optical testing instrument. The specific calculation formula is as follows:

[0153]

[0154] Where ηe is the optical output coupling efficiency, ηr is the ratio of recombination carriers to injected carriers, χ is the ratio of the number of excitons generating photons to the total number of excitons, and K R K is the radiation process rate. NR This represents the rate of a non-radiative process.

[0155] Test conditions: Conducted at room temperature with an air humidity of 30-60%.

[0156] (2) Lifespan T95 1000nit T95 is the time required for a device's brightness to decrease to a certain percentage of its maximum brightness under constant current or voltage driving. This time, when the brightness drops to 95% of its maximum brightness, is defined as the measured lifetime. To shorten the testing cycle, device lifetime testing is typically performed by accelerating device aging at high brightness, referencing OLED device testing. The lifetime at high brightness is then obtained by fitting the extended exponential decay brightness decay formula, for example, the lifetime at 1000 nits is measured as T95. 1000nit The specific calculation formula is as follows:

[0157]

[0158] In the formula, T95 LFor longer lifespan at low brightness, T95 H For the measured lifetime under high brightness, L H To accelerate the device to its maximum brightness, L L The value is 1000 nits, and A is the acceleration factor. For OLEDs, this value is usually 1.6 to 2. In this experiment, the lifetime of several groups of QLED devices under rated brightness was measured, and the value of A was found to be 1.7.

[0159] The life test system was used to test the life of the corresponding devices. The test conditions were: room temperature and air humidity of 30-60%.

[0160] (3) Leakage rate: A test system built using Keithley 2400 and Keithley 6485 was used to detect the current density and voltage relationship curve of the device. The current density at 1V on this curve was taken. Current densities higher than 0.001mA·cm⁻¹ were used. -2 The device with leakage current is recorded as the leakage current. The number of leakage current devices out of 100 of the same type is counted, and the leakage rate is calculated.

[0161] Table 2

[0162]

[0163]

[0164] As can be seen from the table above:

[0165] Device embodiments 1 to 16 all exhibit high external quantum efficiency and lifetime as well as low leakage rate, indicating that the light-emitting device proposed in this application has a high yield rate and better light-emitting performance and lifetime.

[0166] Furthermore, comparing device Example 1 and Comparative Example 1, and Example 16 and Comparative Example 2, it can be seen that devices Example 1 and 16 have significantly higher external quantum efficiency and lifetime, and lower leakage rate. This indicates that by adding thickener and metal carbide before annealing during the preparation of the electron transport layer, it is helpful to improve the annealing effect, reduce the leakage rate, and improve the luminescence performance and lifetime of the device.

[0167] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A film, characterized by, The material of the thin film includes metal oxide nanoparticles, and multiple metal oxide nanoparticles interlock to form an interlocking body. The percentage w of the number of interlocking bodies to the total number of metal oxide nanoparticles in the thin film satisfies 0 ≤ w ≤ 25%.

2. The film according to claim 1, characterized in that, The average particle size of the chimera is greater than or equal to 10 nm; and / or, The porosity of the film is 10–30%; and / or, The average particle size of the metal oxide nanoparticles is 2–5 nm; and / or, The metal oxide nanoparticles include one or more of undoped metal oxides and doped metal oxides. The undoped metal oxides include one or more of ZnO, SnO2, and TiO2. The doped metal oxides are oxides doped with a dopant element, and the oxides include one or more of ZnO, SnO2, and TiO2. The dopant element includes one or more of Al, Mg, Li, In, and Ga. Optionally, the molar percentage of the dopant element in the doped metal oxide is 0.01 to 20%.

3. The film of claim 1, wherein The material of the thin film also includes metal carbides.

4. The film of claim 3, wherein The metal carbide includes one or more of vanadium carbide, trichromium carbide, tantalum carbide, niobium carbide, titanium carbide, molybdenum carbide, zirconium carbide, and hafnium carbide; and / or, In the thin film, the mass ratio of the metal carbide to the metal oxide nanoparticles is 6 to 23:

100.

5. The film of claim 3, wherein The film material further includes a thickener, wherein the mass ratio of the thickener to the metal oxide nanoparticles is 6–23:100; and / or, The thickener comprises one or more of C10-C18 alcohols, C10-C18 acids, polymers, amine oxides, fatty alcohol polyoxyethylene ether sulfates, and ethyl cellulose. The C10-C18 alcohols include one or more of terpineol, lauryl alcohol, and stearyl alcohol. The C10-C18 acids include one or more of stearic acid, linolenic acid, and linoleic acid. The polymers include one or more of polyurethane, polyacrylate, polyethylene glycol, and polyoxyethylene. The amine oxides include one or more of myristotinamide oxide and cocoaminopropylamine oxide.

6. A method of producing a film, characterized by, Includes the following steps: Provide a mixed solution containing a first compound and metal oxide nanoparticles; The mixed solution is deposited and then annealed to obtain a thin film. The first compound includes a first metal carbide.

7. The preparation method according to claim 6, characterized in that, The metal oxide nanoparticles comprise one or more of undoped metal oxides and doped metal oxides. The undoped metal oxides include one or more of ZnO, SnO2, and TiO2. The doped metal oxides are oxides doped with a dopant element, including one or more of ZnO, SnO2, and TiO2, and the dopant element includes one or more of Al, Mg, Li, In, and Ga; and / or, The first metal carbide includes one or more of vanadium carbide, trichromium carbide, tantalum carbide, niobium carbide, titanium carbide, molybdenum carbide, zirconium carbide, and hafnium carbide; and / or, The mass ratio of the first metal carbide to the metal oxide nanoparticles is (6-23):100; and / or, The mixed solution further includes a solvent comprising C1-C8 alcohols, including one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, and octanol; and / or, In the mixed solution, the concentration of the metal oxide nanoparticles is 10–60 mg / mL; and / or, The annealing temperature is 80–120°C; and / or, The annealing process takes 10–20 minutes; and / or, The first compound further includes a thickener, optionally comprising one or more of C10-C18 alcohols, C10-C18 acids, polymers, amine oxides, fatty alcohol polyoxyethylene ether sulfates, and ethyl cellulose. The C10-C18 alcohols include one or more of terpineol, lauryl alcohol, and stearyl alcohol. The C10-C18 acids include one or more of stearic acid, linolenic acid, and linoleic acid. The polymers include one or more of polyurethane, polyacrylate, polyethylene glycol, and polyoxyethylene. The amine oxides include one or more of myristotinamide oxide and cocoaminopropylamine oxide.

8. The preparation method according to claim 7, characterized in that, The mass ratio of the thickener to the metal oxide nanoparticles is 6–23:

100.

9. The preparation method according to claim 6, characterized in that, The steps of providing a mixed solution containing a first compound and metal oxide nanoparticles include: Provide a precursor solution containing a metal salt and an alkali; The precursor solution and alkali are mixed and reacted to obtain a nanoparticle solution containing metal oxide nanoparticles. The nanoparticle solution and the first compound are mixed to obtain the mixed solution; Optionally, the metal salt includes a first metal salt or a mixture of a first metal salt and a second metal salt, wherein the first metal salt includes one or more of zinc salt, tin salt, and titanium salt; the second metal salt includes one or more of aluminum salt, magnesium salt, lithium salt, indium salt, and gallium salt; and / or, The alkali includes one or more of alkali metal oxides, alkali metal hydroxides, alkali metal bicarbonates, alkali metal carbonates, alkaline earth metal oxides, alkaline earth metal hydroxides, and alkaline earth metal bicarbonates; and / or, The mass ratio of the first metal carbide to the metal salt is 3 to 10:100; and / or, The mass ratio of the thickener to the metal salt is 3 to 10:

100.

10. The method of claim 9, wherein, The precursor solution also includes a second metal carbide; Optionally, the second metal carbide includes one or more of vanadium carbide, trichromium carbide, tantalum carbide, niobium carbide, titanium carbide, molybdenum carbide, zirconium carbide, and hafnium carbide; and / or, The total mass ratio of the first metal carbide and the second metal carbide to the metal salt is 3 to 10:

100.

11. A light-emitting device, characterized in that, It includes a stacked cathode, an electron transport layer, and an anode, wherein the electron transport layer comprises the thin film according to any one of claims 1 to 5, or the thin film prepared by the preparation method according to any one of claims 6 to 10.

12. The light emitting device of claim 11, wherein, The light-emitting device further includes a light-emitting layer disposed between the electron transport layer and the anode. The material of the light-emitting layer includes organic light-emitting materials or quantum dots. The organic light-emitting materials include one or more of the following: diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent materials, TTPA fluorescent materials, TBRb fluorescent materials, and DBP fluorescent materials. The quantum dots include one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The shell of the core-shell structure quantum dots includes one or more layers. The material of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots respectively include group II-VI compounds, group I... One or more of group V-VI compounds, group III-V compounds, and group I-III-VI compounds; wherein the group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, Cd The compounds are selected from one or more of HgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the group IV-VI 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 group III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and GaNP. One or more of GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the group I-III-VI 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 general structural formula of the inorganic perovskite semiconductor is AMX3, where A is Cs; + Ion, M is a divalent metal cation selected from Pb 2 + Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, where X is a halide anion selected from 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 selected from CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of the following, where X is a halide anion selected from Cl... - ,Br - I - One or more of the following; and / or, The anode and cathode each independently include a doped metal oxide particle electrode, a metal-metal oxide composite electrode, a graphene electrode, a carbon nanotube electrode, a metal electrode, or an alloy electrode. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, and ZnS / Al / ZnS. The material of the metal electrode is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba; and / or, The light-emitting device further includes a hole functional layer disposed between the electron transport layer and the anode. The hole functional layer comprises one or both of a hole transport layer and a hole injection layer. When the hole functional layer comprises both a hole transport layer and a hole injection layer, the hole transport layer is located between the anode and the hole injection layer. The material of the hole transport layer includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], and 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-3-methylphenyl-N-phenylamino)triphenylamine, poly(p-)phenylenevinylene, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'-diphenylenevinylene] [Methyloctyloxy]-1,4-phenylenevinylene, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS, poly(N-vinylcarbazole), polymethacrylate, poly(9,9-octylfluorene), N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine, spiron NPB, doped graphene, undoped graphene, C60, and one or more transition metal oxides, wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO; the material of the hole injection layer includes poly( 3,4-ethylenedioxythiophene), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethane, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, copper polyester carbonate, transition metal oxides, and metal chalcogenides; wherein the transition metal oxides include one or more of NiO, MoO2, WO3, and CuO; and the metal chalcogenides include one or more of MoS2, MoSe2, WS3, WSe3, and CuS; and / or, The light-emitting device further includes an electron injection layer disposed between the electron transport layer and the cathode, the material of which includes one or more of LiF, MgP, MgF2, Al2O3, Ga2O3, LiF / Yb, ZnO, Cs2CO3, RbBr, and Rb2CO3.

13. A display device comprising: Includes the light-emitting device as described in claim 11 or 12.

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