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

Abstract

The invention discloses a composite material and a preparation method thereof, a thin film, a photoelectric device and a display device, the composite material comprises metal oxide nanoparticles and a shell layer coating the surfaces of the metal oxide nanoparticles, and the material of the shell layer comprises alkali metal halide. According to the composite material provided by the technical scheme of the invention, the surfaces of the metal oxide nanoparticles are coated with the alkali metal halide, so that the stability of the metal oxide nanoparticles in the electrifying process is improved, and the electrochemical change is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a composite material and a preparation method thereof, a thin film, a photoelectric device and a display device. BACKGROUND

[0002] Metal oxides are a kind of electronic materials with semiconductor properties, which can be used to make semiconductor devices and integrated circuits, such as zinc oxide nanoparticles, titanium dioxide nanoparticles, tin oxide nanoparticles, etc. However, in practical applications, it is found that metal oxides are easily affected by water and oxygen environment, resulting in performance degradation. SUMMARY

[0003] Therefore, the present application provides a composite material and a preparation method thereof, a thin film, a photoelectric device and a display device.

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

[0005] In a first aspect, the embodiments of the present application provide a composite material, comprising metal oxide nanoparticles and a shell layer coated on the surface of the metal oxide nanoparticles, wherein the material of the shell layer comprises alkali metal halide.

[0006] In a second aspect, the embodiments of the present application provide a preparation method of the composite material, comprising the following steps:

[0007] Providing a mixed solution, wherein the mixed solution comprises metal oxide nanoparticles, alkali metal halide and organic solvent;

[0008] Heat treating the mixed solution to obtain the composite material.

[0009] In a third aspect, the embodiments of the present application provide a thin film, wherein the material of the thin film comprises the composite material as described above, or comprises the composite material prepared by the preparation method as described above.

[0010] In a fourth aspect, the embodiments of the present application provide a photoelectric device, comprising an anode, an electron functional layer and a cathode which are arranged in layers, wherein the electron functional layer comprises the thin film as described above.

[0011] In a fifth aspect, the present application provides a display device comprising the photoelectric device as described above.

[0012] The composite material provided by the technical scheme of the present application can reduce the adverse effects of water and oxygen on metal oxide nanoparticles by coating alkali metal halide on the surface of the metal oxide nanoparticles, which helps to improve the stability of the metal oxide during the electrification process and reduce the electrochemical changes. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and all other drawings obtained by those skilled in the art without creative effort based on these drawings also belong to the protection scope of the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain and illustrate the present application, and should not be used to limit the present application. In the present application, the positional words such as "upper" and "lower" are the directions of the drawing surface in the drawings. In addition, in the description of the present application, the term "comprising" means "comprising but not limited to". Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit to the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values in the 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 in the range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in the present application, it means that any quoted number (fraction or integer) in the indicated range is included.

[0014] Figure 1 is a structural schematic diagram of a composite material provided by an embodiment of the present application;

[0015] Figure 2 is a structural schematic diagram of an optoelectronic device provided by an embodiment of the present application;

[0016] The drawings are as follows: composite material 1; metal oxide nanoparticles 11; shell layer 12; optoelectronic device 100; anode 10; cathode 20; light-emitting layer 30; hole transport layer 40, hole injection layer 50, and electron functional layer 60. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some 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 effort belong to the protection scope of the present application. In addition, it should be understood that the specific embodiments described herein are only used to explain and illustrate the present application, and should not be used to limit the present application. In the present application, the positional words such as "upper" and "lower" are the directions of the drawing surface in the drawings. In addition, in the description of the present application, the term "comprising" means "comprising but not limited to". Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limit to the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values in the 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 in the range, such as 1, 2, 3, 4, 5 and 6, which applies to any range. In addition, whenever a numerical range is indicated in the present application, it means that any quoted number (fraction or integer) in the indicated range is included.

[0018] In the present application, the association relationship of the associated objects is described as "and / or", which means that there can be three relationships, for example, A and / or B, which can mean that A exists alone, A and B exist together, and B exists alone. Wherein A and B can be singular or plural.

[0019] In this application, "at least one" means one or more, "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of these items, including single item or any combination of multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can represent: a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0020] In a first aspect, embodiments of the present application propose a composite material 1, please refer to Figure 1 The composite material 1 includes metal oxide nanoparticles 11 and a shell layer 12 coated on the surface of the metal oxide nanoparticles 11, and the material of the shell layer 12 includes alkali metal halide.

[0021] The metal oxide is easily affected by water and oxygen environment, resulting in its performance decline; in addition, after the nanoparticles are formed into a film, under the action of heating or electric heating, the nanoparticles will cross-link due to chemical action between the nanoparticles, resulting in grain growth, and further resulting in changes in the properties of the nanoparticles. In view of this, the present application proposes a composite material 1, which coats alkali metal halide on the surface of the metal oxide nanoparticles 11, which can reduce the adverse effects of water and oxygen and other substances on the metal oxide, reduce the fusion changes of the nanoparticles caused by the thermal effect of the metal oxide under heating or electric heating environment, and help to improve the stability of the metal oxide during power-on process, reduce the electrochemical changes, and when the composite material 1 is used in the optoelectronic device 100, the performance of the device can be improved; in addition, by adjusting the thickness of the shell layer 12 composed of alkali metal halide, the tunneling effect of electrons can be adjusted, thereby improving the electron injection capability, and when the composite material 1 is used in the optoelectronic device 100, the potential barrier of the electrons from the electrode to the light-emitting layer 30 can be reduced, the electron injection can be improved, and the efficiency of the device can be improved.

[0022] In some embodiments, in the composite material 1, the alkali metal element is doped on the surface of the metal oxide nanoparticles 11, and at the same time, the halogen element occupies some oxygen vacancies of the metal oxide, thereby forming a transition layer of metal oxide / alkali metal halide between the core of the metal oxide nanoparticles 11 and the shell layer 12 of alkali metal halide.

[0023] In some embodiments, the metal oxide nanoparticles 11 include one or more of undoped oxides and doped oxides; the undoped oxides include at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, and the oxides in the doped oxides include at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, and the doping element includes at least one of Al, Mg, Li, In, and Ga.

[0024] The alkali metal halide may include alkali metal cations and halide anions, wherein the alkali metal cations include Na. + K + Li + 、Rb + Cs + 、Fr + One or more of the following, wherein the halide anion includes F - Cl - ,Br - I - One or more of the following. For example, the alkali metal halide may include, but is not limited to, one or more of NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, LiF, LiCl, LiBr, LiI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr, CsI, FrF, FrCl, FrBr, and FrI.

[0025] In some embodiments, the alkali metal halide may include one or more alkali metal fluorides, such as NaF, KF, LiF, RbF, CsF, and FrF. NaF, KF, LiF, RbF, CsF, and FrF exhibit relatively good stability to water, oxygen, heat, and electric fields, and have a certain ability to regulate the electron tunneling properties of metal oxides.

[0026] In other embodiments, the metal oxide nanoparticles 11 are ZnO nanoparticles, and the shell 12 is a NaF shell. That is, the composite material 1 consists of ZnO nanoparticles and a NaF shell coating the surface of the ZnO nanoparticles, referred to as ZnO@NaF. ZnO@NaF exhibits better stability to water, oxygen, heat, and electric fields, as well as tunable electron tunneling properties.

[0027] In some embodiments, the average particle size of the metal oxide nanoparticles 11 is 3 to 12 nm; for example, it can be 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, or any two of the above values.

[0028] In some embodiments, the thickness of the shell layer 12 is 0.3 to 5 nm; for example, it can be 0.3 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, or any value between any two of the above.

[0029] In some embodiments, the average particle size of the composite material 1 is 3.3–17 nm; for example, it can be 3.3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, or any value between any two of the above. In other embodiments, the average particle size of the composite material 1 is 4–13 nm.

[0030] It is understandable that the average particle size mentioned in this article can be detected by transmission electron microscopy (TEM).

[0031] It is understood that the surface of the shell 12 can be further coated with other shells, such as metal oxide materials such as tin dioxide and titanium dioxide.

[0032] Secondly, this application also proposes a method for preparing composite material 1, which can prepare composite material 1 with metal oxide nanoparticles 11 as the core and alkali metal halide as the shell 12. The composite material 1 has good stability against water, oxygen, heat, electric field, etc., and tunable electron tunneling properties. The composite material 1 can be the composite material 1 described above, possessing the characteristics of the aforementioned composite material 1.

[0033] In some embodiments, the preparation method includes the following steps:

[0034] S10, providing a mixed solution, wherein the mixed solution comprises metal oxide nanoparticles 11, alkali metal halide and organic solvent;

[0035] S20, the mixed solution is heat-treated to obtain composite material 1.

[0036] In step S10:

[0037] In some embodiments, the metal oxide nanoparticles 11 include one or more of undoped oxides and doped oxides; the undoped oxides include at least one of ZnO, TiO2, SnO2, Ga2O3 and Al2O3, the oxides in the doped oxides include at least one of ZnO, TiO2, SnO2, Ga2O3 and Al2O3, and the doping elements in the doped oxides include at least one of Al, Mg, Li, In and Ga.

[0038] In some embodiments, the alkali metal halide comprises an alkali metal cation and a halide anion, wherein the alkali metal cation includes Na. + K + Li + 、Rb + Cs + and Fr + One or more of the following, wherein the halide anion includes F - Cl - ,Br - and I - One or more of them.

[0039] In some embodiments, the organic solvent comprises one or more of C8 to C18 organic acids, including octanoic acid, decanoic acid, heptanoic acid, oleic acid, stearic acid, dodecanoic acid, tetradecanoic acid, and hexadecanoic acid. It is understood that stearic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, etc., can be used as solvents after being heated and melted, or they can be directly mixed with alkali metal halides, etc., and then heated to form a mixed solution.

[0040] In the mixed system of metal oxide nanoparticles 11, alkali metal halides and organic solvents, the organic solvents provide a liquid reaction environment, and their organic acid anions can react with alkali metal ions to form salts, so that alkali metal elements can be incorporated into the surface of metal oxide nanoparticles 11. At the same time, they can act as coordination solvents, which can stabilize nanoparticles and regulate reaction activity through steric hindrance.

[0041] In some embodiments, the molar ratio of the alkali metal halide to the metal element in the metal oxide nanoparticles 11 is 1:2 to 4; for example, it can be 1:2, 1:2.2, 1:2.5, 1:2.8, 1:3, 1:3.3, 1:3.5, 1:3.7, 1:4, and any two of the above values.

[0042] In some embodiments, prior to step S10, the preparation method further includes a step of preparing the mixed solution, wherein the step of preparing the mixed solution includes:

[0043] S101, a metal precursor and a first solvent are provided, the metal precursor and the first solvent are mixed, and a first reaction is carried out to obtain a first mixture containing an organometallic complex;

[0044] S102, a second solvent is provided, and the second solvent and the first mixture are mixed to react and obtain a second mixture containing metal oxide nanoparticles 11;

[0045] S103, providing an alkali metal halide and an organic solvent, mixing the second mixture, the alkali metal halide and the organic solvent to obtain a mixed solution containing metal oxide nanoparticles 11, alkali metal halide and organic solvent.

[0046] In step S101:

[0047] The first solvent may include one or more of octadecene, paraffin oil, tetrahydrofuran, silicone oil, octafluorocyclohexane, and polycyclopentadiene.

[0048] The metal precursor may include an organic acid salt containing a metal element, wherein the metal element includes at least one of Zn, Ti, Sn, Ga, Al, Mg, Li, In, and Ga, and the organic acid anion in the organic acid salt includes at least one of stearate, oleate, dodecylate, tetradecylate, and hexadecylate; taking the Zn precursor as an example, it may specifically be one or more of zinc oleate, zinc stearate, zinc dodecanoate, zinc tetradecanoate, and zinc hexadecanoate.

[0049] In some embodiments, the molar ratio of the first solvent to the metal element in the metal precursor is 2.2 to 3:1; for example, it can be 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, or any two of the above values. By adjusting the ratio of the first solvent to the metal precursor, the reaction rate and the activity of the monomer can be effectively controlled.

[0050] In some embodiments, step S101 may be implemented as follows: mixing the metal precursor and the first solvent, evacuating at a first temperature, and then carrying out a first reaction at a second temperature under an inert atmosphere.

[0051] The first temperature is 120-140℃, for example, it can be 120℃, 125℃, 130℃, 135℃, 140℃ and any two of the above values; the second temperature is 270-290℃, for example, it can be 270℃, 275℃, 280℃, 285℃, 290℃ and any two of the above values.

[0052] In some embodiments, the vacuuming time can be 25 to 60 minutes; for example, it can be 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, or any value between any two of the above.

[0053] In some embodiments, the time for the first reaction can be 25 to 60 minutes; for example, it can be 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, or any two of the above values.

[0054] In some embodiments, the inert atmosphere may include, but is not limited to, one or more of nitrogen, argon, and helium.

[0055] By evacuating the system at the first temperature, impurities such as water and short-chain organic compounds can be removed to some extent. Furthermore, at the second temperature, the metal precursor undergoes a complexation reaction with the first solvent to generate an organometallic complex.

[0056] Returning to S10, the amount of organic solvent used can be: the molar ratio of the organic solvent to the first solvent can be 1:1 to 1.2; for example, 1:1, 1:1.1, 1:1.2, and any two of the above values.

[0057] In step S102:

[0058] The second solvent may include a mixed solution of an alcohol compound and solvent A, wherein the alcohol compound includes one or more of C6 to C18 alcohol compounds, wherein the C6 to C18 alcohol compounds include one or more of hexanol, octanol, dodecanol, tetradecyl alcohol, hexadecyl alcohol, and octadecyl alcohol, and solvent A includes one or more of octadecene, paraffin oil, tetrahydrofuran, disodium silicone oil, octafluorocyclohexane, and polycyclopentadiene.

[0059] The second solvent can activate the metal precursor and promote its nucleation reaction. Simultaneously, by adjusting the ratio of the alcohol compound to solvent A, the reaction rate and reactant activity can be controlled.

[0060] In some embodiments, the second solvent can be obtained by dissolving the alcohol compound in solvent A, wherein the concentration of the alcohol compound in the mixed solution can be 0.8 to 1.2 mmol / g; to help the alcohol compound dissolve better, the dissolution process can be carried out under heating conditions, wherein the heating temperature can be 180 to 200°C.

[0061] In some embodiments, step S102 may specifically include:

[0062] S1021, the second solvent and the first mixture are mixed to carry out a second reaction to obtain a reaction mixture;

[0063] S1022, a third solvent is provided, and the third solvent and the reaction mixture are mixed to carry out a third reaction to obtain a third mixture containing metal oxide nanoparticles 11.

[0064] In some embodiments, the temperature of the second reaction is 240–260°C; for example, it can be 240°C, 245°C, 250°C, 255°C, 260°C, or any value between any two of the above.

[0065] In some embodiments, the time for the second reaction is 5 to 10 minutes; for example, it can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any value between any two of the above.

[0066] In some embodiments, the third solvent comprises a mixed solution of an acid compound and solvent B. The acid compound comprises one or more of C8 to C18 organic acids, including octanoic acid, capric acid, heptanoic acid, oleic acid, stearic acid, dodecanoic acid, tetradecanoic acid, and hexadecanoic acid. The solvent B comprises one or more of octadecene, paraffin oil, tetrahydrofuran, disodium silicate, octafluorocyclohexane, and polycyclopentadiene. In some embodiments, the third solvent can be obtained by dissolving the acid compound in solvent B. The concentration of the acid compound in the mixed solution can be 0.3–0.5 mmol / g. To facilitate better dissolution of the acid compound, the dissolution process can be carried out under heating conditions, with the heating temperature being 110–130°C.

[0067] Introducing some free ligand fatty acids into the reaction system can stabilize the reactants that are resoluble during the ripening reaction, regulate the reactivity of the ripening reaction, and thus control the shape and size of the product nanocrystals.

[0068] In some embodiments, the temperature of the third reaction is 240–260°C; for example, it can be 240°C, 245°C, 250°C, 255°C, 260°C, or any two of the above values.

[0069] In some embodiments, the time for the third reaction is 60 to 90 minutes; for example, it can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, or any value between any two of the above.

[0070] In some embodiments, the molar ratio of the alcohol compound in the second solvent to the metal element in the metal precursor is 1:0.15 to 0.25; for example, it can be 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19, 1:0.2, 1:0.21, 1:0.22, 1:0.23, 1:0.24, 1:0.25, and any two of the above values.

[0071] In some embodiments, the molar ratio of the acid compound in the third solvent to the metal element in the metal precursor is 1:0.8 to 1; for example, it can be 1:0.8, 1:0.82, 1:0.85, 1:0.88, 1:0.9, 1:0.93, 1:0.95, 1:0.97, 1:1, and any two of the above values.

[0072] In some embodiments, solvent A, solvent B, and the first solvent may be selected from the same type of compound.

[0073] In step S20:

[0074] The heat treatment temperature is 260–300°C; for example, it can be 260°C, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C, 295°C, 300°C, or any two of the above values. Controlling the temperature within this range can promote the reaction kinetics of the material, promote material growth, and control particle size.

[0075] In some embodiments, the heat treatment time is 60 to 90 minutes; for example, it can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, or any value between any two of the above.

[0076] Thirdly, this application also proposes a thin film, the material of which is a composite material 1 prepared by the preparation method described above, or a composite material 1 as described above. The thin film has good thermal stability and water-oxygen stability, and good electron tunneling characteristics, and can be used as the electronic functional layer 60 of an optoelectronic device 100.

[0077] Fourthly, this application also proposes an optoelectronic device 100, which includes, but is not limited to, organic light-emitting diodes, quantum dot light-emitting diodes, photovoltaic cells, and photodetectors. The optoelectronic device 100 can be a positively oriented device or an inverted device. Please refer to [link to relevant documentation]. Figure 2 The optoelectronic device 100 includes an anode 10, a cathode 20, and an electronic functional layer 60 disposed between the anode 10 and the cathode 20. The electronic functional layer 60 includes the thin film described above. The material of the electronic functional layer 60 is a composite material 1 prepared by the preparation method described above, or includes the composite material 1 described above.

[0078] The composite material 1 proposed in this application coats the surface of metal oxide nanoparticles 11 with alkali metal halides, which can reduce the adverse effects of metal oxides on substances such as water and oxygen, reduce the fusion changes of nanoparticles caused by thermal effects of metal oxides, help improve their stability during the energization process, and reduce electrochemical changes. When this composite material 1 is used in optoelectronic device 100, it can improve the performance of the device. In addition, by controlling the thickness of the shell 12 composed of alkali metal halide, the electron tunneling effect can be controlled, thereby improving its electron injection capability. When this composite material 1 is used in optoelectronic device 100, it can reduce the potential barrier for electrons to be injected from the electrode to the light-emitting layer 30, improve electron injection, and improve the efficiency of the device.

[0079] The anode 10 and the cathode 20 are each independently selected from doped metal oxide particle electrodes, metal-metal oxide composite electrodes, graphene electrodes, carbon nanotube electrodes, metal electrodes, or alloy electrodes. The material of the doped metal oxide particle electrode is selected from one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The metal-metal oxide composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, and ITO / Ag. The metal electrode material is selected from one or more of Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg, and Ba; where " / " indicates a stacked structure. For example, the composite electrode AZO / Ag / AZO represents a three-layer stacked composite structure consisting of an AZO layer, an Ag layer, and an AZO layer.

[0080] In addition to the anode 10 and the cathode 20, the optoelectronic device 100 may also have other intermediate film layers disposed between the anode 10 and the cathode 20, such as including but not limited to a hole functional layer, a light-emitting layer 30, etc. The light-emitting layer 30 may be disposed between the electronic functional layer 60 and the anode 10; the hole functional layer may be disposed between the anode 10 and the light-emitting layer 30; the hole functional layer includes one or both of a hole injection layer 50 and a hole transport layer 40, with the hole injection layer 50 located between the hole transport layer 40 and the anode 10. When the optoelectronic device 100 simultaneously includes a hole transport layer 40, a hole injection layer 50, and a light-emitting layer 30, the film layer structure of the optoelectronic device 100 is as follows: the anode 10, hole injection layer 50, hole transport layer 40, light-emitting layer 30, electronic functional layer 60, and cathode 20 are stacked sequentially; or, the cathode 20, electronic functional layer 60, light-emitting layer 30, hole transport layer 40, hole injection layer 50, and anode 10 are stacked sequentially. It is understood that when one or more of the above-mentioned film layers are omitted, the remaining film layers are still arranged in the above-mentioned stacking order. For example, when the optoelectronic device 100 does not include the light-emitting layer 30, the remaining film layers it contains are stacked in the following order: anode 10, hole injection layer 50, hole transport layer 40, electron functional layer 60, and cathode 20 are stacked in sequence, or cathode 20, electron functional layer 60, hole transport layer 40, hole injection layer 50, and anode 10 are stacked in sequence.

[0081] The material of the light-emitting layer 30 can be a conventional light-emitting material in the art, such as organic light-emitting materials or quantum dot light-emitting materials. The organic light-emitting materials include 4,4'-bis(N-carbazole)-1,1'-biphenyl:tris[2-(p-tolyl)pyridinium(III), 4,4',4”-tris(carbazole-9-yl)triphenylamine:tris[2-(p-tolyl)pyridinium, diaromatic anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescence materials, and TTA. The quantum dot luminescent material comprises one or more of the following: thermally activated delayed materials, polymers containing BN covalent bonds, hybrid localized charge transfer excited-state materials, and exciton complex luminescent materials; the quantum dot luminescent material may include, but is not limited to, at least one of 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 materials of the single-structure quantum dots, the core materials of the core-shell quantum dots, and the shell materials of the core-shell quantum dots independently include group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-II compounds. At least one of group II-VI compounds; said 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, C The group IV-VI compounds include at least one of dZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe;The III-V compounds include at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb; the I-III-VI compounds include at least one of CuInS2, CuInSe2 and AgInS2. As an example, the quantum dots of the core-shell structure can be selected from but not limited to at least one of CdZnSe / CdZnSe / ZnSe / CdZnS / ZnS, CdZnSe / CdZnSe / CdZnS / ZnS CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS and InP / ZnSe / ZnS. It should be noted that for the materials of the aforementioned single-structure quantum dots, or the materials of the core of the core-shell structure quantum dots, or the materials of the shell of the core-shell structure quantum dots, the provided chemical formulas only indicate the elemental composition and do not indicate the content of each element. For example, CdZnSe only represents being composed of three elements Cd, Zn and Se. If indicating the content of each element, it corresponds to Cd; x Zn 1-x Se, 0 < x < 1. The perovskite semiconductor materials include doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors; the structural general formula of the inorganic perovskite semiconductors is AMX3, where A is Cs + 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+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of the following; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein 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+ At least one of them, where X is a halide anion selected from Cl. - ,Br - I - At least one of them.

[0082] The material of the hole functional layer can be a hole injection material or a hole transport material commonly used in optoelectronic devices in this field. Hole transport materials can include, but are 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), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NPD), and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4”-diamine. '-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), tris(3-methylphenylphenylamino)-triphenylamine (m-MTDATA), poly(p-phenylenevinylene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-P) PV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (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), spiron NPB One or more of the following; the hole injection material may include, but is not limited to, at least one of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethyl ether, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0083] In some embodiments, the thickness of the bottom electrode is 20–200 nm; the thickness of the top electrode is 40–190 nm; the thickness of the hole injection layer 50 is 20–200 nm; the thickness of the hole transport layer 40 is 30–180 nm; the total thickness of the light-emitting layer 30 is 30–180 nm; and the thickness of the electronic functional layer 60 is 10–180 nm. It can be understood that the bottom electrode can be one of the anode 10 and the cathode 20, and the top electrode can be the other of the anode 10 and the cathode 20.

[0084] It is understood that the optoelectronic device 100 may also be provided with some functional layers that are conventionally used in optoelectronic devices 100 and help to improve the performance of optoelectronic devices 100, such as electron blocking layer, hole blocking layer, interface modification layer, etc.

[0085] It is understood that the materials of each layer of the optoelectronic device 100 can be adjusted according to the actual needs of the optoelectronic device 100.

[0086] In some embodiments, the optoelectronic device 100 may further include a substrate disposed on the side of the anode 10 or cathode 20 away from the electronic functional layer 60. The substrate may include rigid or flexible substrates, specifically including glass, silicon wafers, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, polyethersulfone, or combinations thereof.

[0087] In some embodiments, the optoelectronic device 100 may further include an encapsulation layer (not shown) to isolate water and oxygen (e.g., to reduce the concentration of oxygen and water to below 0.1 ppm), thereby improving the performance stability of the optoelectronic device 100. Specifically, the encapsulation material used to form the encapsulation layer may be selected from at least one of UV adhesive, metal film, and glass adhesive. In one specific embodiment, the encapsulation material may be acrylic resin or epoxy resin.

[0088] Based on the aforementioned optoelectronic device 100, a method for fabricating the optoelectronic device 100 is further proposed. The fabrication method includes: sequentially fabricating multiple film layers according to a predetermined film layer order to obtain the optoelectronic device 100; wherein, the predetermined film layer order refers to the order in which the optoelectronic device 100 is stacked from bottom to top.

[0089] The methods for forming the various film layers can be chemical or physical. Chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods 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 optoelectronic device 100 of this application embodiment according to the known methods for preparing optoelectronic devices 100, which will not be elaborated further here.

[0090] In some embodiments, in order to accelerate the forward aging of the device, the freshly prepared device may be heat-treated at 60–150°C for 1 min–48 h.

[0091] Fifthly, this application also relates to a display device, which includes the optoelectronic 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.

[0092] 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.

[0093] Material Example 1

[0094] 1. Weigh zinc oleate and octadecene (ODE) into a 50 ml three-necked flask according to a molar ratio of 2.5:1 for octadecene to zinc ions, and treat under vacuum at 130 °C for 50 min. Then, under an argon atmosphere, heat to 280 °C and treat for 30 min to obtain the first mixture.

[0095] 2. Dissolve octadecyl alcohol in ODE at 200℃ to obtain a first mixed solution with an octadecyl alcohol concentration of 1 mmol / g. Cool the first mixture obtained in step 1 to 250℃, and inject it into the first mixed solution at a molar ratio of octadecyl alcohol to zinc ions of 1:0.2. React for 8 min to obtain a second mixture.

[0096] 3. Oleic acid was dissolved in ODE at 120℃ to obtain a second mixed solution with an oleic acid concentration of 0.4 mmol / g. The second mixed solution was then added to the second mixture at a molar ratio of oleic acid to zinc ions of 1:1, and the reaction was continued at 250℃ for 75 min to obtain a third mixture containing ZnO nanoparticles. TEM analysis (average particle size measurements below were performed using TEM) showed that the average particle size of the ZnO nanoparticles was approximately 4 nm.

[0097] 4. Raise the temperature of the third mixture to 280℃, add 10ml of oleic acid and 0.13mmol of NaF, react for 75min to obtain the fourth mixture, wherein the molar ratio of oleic acid to octadecene in step 1 is 1:1, and the molar ratio of NaF to zinc ions is 1.3:4.

[0098] 5. Mix 10 ml of ethyl acetate and 15 ml of ethanol as a cleaning solution, preparing two tubes for later use. Cool the fourth mixture to 50°C, add it to the cleaning solution, and centrifuge at 7300 rpm for 3 minutes. After separation, discard the supernatant, repeat the centrifugation steps, collect the solid product, and dry it to obtain the composite material ZnO@NaF. The average particle size of ZnO@NaF was measured to be approximately 5.6 nm, equivalent to a shell thickness of approximately 1.6 nm.

[0099] 6. Take ZnO@NaF and disperse it with n-hexane to obtain a composite material solution with a concentration of 30 mg / ml, i.e., a hexane solution of ZnO@NaF.

[0100] Material Example 2

[0101] The scheme in this embodiment is basically the same as that in embodiment 1, the only difference being in step 1 of this embodiment:

[0102] Zinc oleate is replaced with titanium oleate. Accordingly, the reaction product in step 5 is TiO2@NaF, and the composite material solution in step 6 is a hexane solution of TiO2@NaF.

[0103] The tests showed that the average particle size of TiO2 nanoparticles was about 4 nm, and the average particle size of TiO2@NaF was about 5.5 nm, which is equivalent to a shell thickness of about 1.5 nm.

[0104] Material Example 3

[0105] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0106] NaF is replaced with NaCl. Accordingly, the reaction product in step 5 is ZnO@NaCl, and the composite material solution in step 6 is a hexane solution of ZnO@NaCl.

[0107] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaCl was approximately 5.7 nm, which is equivalent to a shell thickness of approximately 1.7 nm.

[0108] Material Example 4

[0109] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0110] NaF is replaced with LiF. Accordingly, the reaction product in step 5 is ZnO@LiF, and the composite material solution in step 6 is a hexane solution of ZnO@LiF.

[0111] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@LiF was approximately 5.7 nm, which is equivalent to a shell thickness of approximately 1.7 nm.

[0112] Material Example 5

[0113] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0114] The amount of NaF added was changed to 0.1 mmol.

[0115] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 4.6 nm, which is equivalent to a shell thickness of approximately 0.6 nm.

[0116] Material Example 6

[0117] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0118] The amount of NaF added was changed to 0.2 mmol.

[0119] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 6.5 nm, which is equivalent to a shell thickness of approximately 2.5 nm.

[0120] Material Example 7

[0121] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0122] The amount of NaF added was changed to 0.05 mmol.

[0123] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 4.3 nm, which is equivalent to a shell thickness of approximately 0.3 nm.

[0124] Material Example 8

[0125] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0126] The amount of NaF added was changed to 0.3 mmol.

[0127] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 7.7 nm, which is equivalent to a shell thickness of approximately 3.7 nm.

[0128] Material Example 9

[0129] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0130] The reaction temperature was changed to 250℃.

[0131] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 4.6 nm, which is equivalent to a shell thickness of approximately 0.6 nm.

[0132] Material Example 10

[0133] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0134] The reaction temperature was changed to 260℃.

[0135] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 4.8 nm, which is equivalent to a shell thickness of approximately 0.8 nm.

[0136] Material Example 11

[0137] The scheme in this embodiment is basically the same as that in embodiment 1, except that in step 4 of this embodiment:

[0138] The reaction temperature was changed to 300℃.

[0139] The average particle size of ZnO nanoparticles was found to be approximately 4 nm, and the average particle size of ZnO@NaF was approximately 6.9 nm, which is equivalent to a shell thickness of approximately 2.9 nm.

[0140] Material Comparison Example 1

[0141] This comparative example is basically the same as Example 1, except that in this comparative example:

[0142] Steps 4 and 5 are omitted;

[0143] Step 6 is changed to:

[0144] Prepare two tubes of the washing solution by mixing 10 ml of ethyl acetate and 15 ml of ethanol. Cool the third mixture to 50°C, add it to the washing solution, and centrifuge at 7300 rpm for 3 min. After separation, discard the supernatant, repeat the centrifugation steps, collect the solid product, and dry it to obtain ZnO.

[0145] ZnO was dispersed in n-hexane to obtain a ZnO n-hexane solution with a concentration of 30 mg / ml.

[0146] Material Comparison Example 2

[0147] This comparative example is basically the same as Example 2, except that in this comparative example:

[0148] Steps 4 and 5 are omitted;

[0149] Step 6 is changed to:

[0150] Prepare two tubes of the washing solution by mixing 10 ml of ethyl acetate and 15 ml of ethanol. Cool the third mixture to 50°C, add it to the washing solution, and centrifuge at 7300 rpm for 3 min. After separation, discard the supernatant, repeat the centrifugation steps, collect the solid product, and dry it to obtain TiO2.

[0151] TiO2 was dispersed in n-hexane to obtain a TiO2 n-hexane solution with a concentration of 30 mg / ml.

[0152] Thin Film Example 1

[0153] The composite material solution obtained in Material Example 1, ZnO@NaF in n-hexane solution, was spin-coated onto a glass substrate and vacuum dried to form a film with a thickness of approximately 35 nm.

[0154] Thin Film Examples 2 to 11

[0155] The scheme of thin film embodiment n is basically the same as that of thin film embodiment 1, except that in step (5) of thin film embodiment n, the composite material solution is the composite material solution in step 6 of material embodiment n. n is any integer from 2 to 11.

[0156] Thin Film Comparative Example 1

[0157] The comparative example scheme of this film is basically the same as that of film example 1, except that in step (5) of this comparative example, the composite material solution is the ZnO solution in material comparative example 1.

[0158] Thin Film Comparative Example 2

[0159] The comparative scheme of this thin film is basically the same as that of the thin film example 1, except that in step (5) of this comparative scheme, the composite material solution is the TiO2 solution in the material comparative example 2.

[0160] Device Example 1

[0161] (1) A glass substrate with an ITO anode layer on its surface is provided, and the anode thickness is 80 nm.

[0162] (2) PEDOT:PSS was spin-coated onto ITO with a thickness of 20 nm and dried under vacuum to form a hole injection layer.

[0163] (3) A chlorobenzene solution of TFB (TFB concentration of 10 mg / mL) with a thickness of 20 nm was spin-coated onto the hole injection layer and dried under vacuum to form a film, thus obtaining the hole transport layer.

[0164] (4) A hexane solution of blue quantum dots CdZnSe / CdZnSe / CdZnS (concentration of blue quantum dots: 25 mg / mL) was spin-coated onto the hole transport layer to a thickness of 40 nm. The solution was then vacuum-dried to form a luminescent layer. The luminescent layer was then subjected to UV irradiation with a dose of 100 mJ / cm². 2 Illumination time: 6 minutes.

[0165] (5) Spin-coating the composite material solution prepared in Example 1 - ZnO@NaF n-hexane solution with a thickness of 35 nm onto the light-emitting layer, and vacuum drying to form a film to obtain an electron transport layer.

[0166] (6) A 15nm thick semi-transparent cathode Ag is deposited on the electron transport layer, with a thickness of 100nm.

[0167] (7) After the device is fabricated, the device is heat-treated at 120°C for 15 minutes to obtain the QLED device.

[0168] Device Examples 2 to 11

[0169] Device embodiment n is basically the same as device embodiment 1, except that in step (5) of device embodiment n, the composite material solution is the composite material solution in step 6 of material embodiment n. n is any integer from 2 to 11.

[0170] Device Comparison Example 1

[0171] The comparative scheme of this device is basically the same as that of device embodiment 1, except that in the comparative step (5) of this device, the composite material solution is the ZnO solution in material comparative example 1.

[0172] Device Comparison Example 2

[0173] The comparative scheme of this device is basically the same as that of device embodiment 1, except that in the comparative step (5) of this device, the composite material solution is the TiO2 solution in material comparative example 2.

[0174] Experimental Example

[0175] (a) The thin films prepared in the thin film examples and the thin film comparative examples were tested for their properties. The results are shown in Table 1.

[0176] The detection method is as follows:

[0177] (1) Water and oxygen stability test: After placing the film in air at 25°C and 85% humidity for 1 hour, the band gap of the material in the film is tested.

[0178] (2) Thermal stability test: The film was placed in a vacuum environment, heated to 85°C, and left for 24 hours to test the band gap of the film.

[0179] One method for detecting the band gap is as follows: In ultraviolet photoelectron spectroscopy (UPS), the energy difference between the valence band top and the Fermi level is obtained by measuring the kinetic energy of ultraviolet photoelectrons emitted from the surface of the sample. Then, by combining this with the Fermi level position measured by X-ray photoelectron spectroscopy (XPS), the band gap can be estimated.

[0180] Table 1

[0181]

[0182]

[0183] As can be seen from the table above:

[0184] After the water and oxygen stability test and before and after the thermal stability test, the band gap of thin film Examples 1 to 11 decreased by a small amount. Among them, the decrease of thin film Examples 1 and 5 to 11 was significantly smaller than that of thin film Comparative Example 1, and the decrease of thin film Example 2 was significantly smaller than that of thin film Comparative Example 2. This shows that coating the surface of metal oxide with alkali metal halide in this application helps to improve the water and oxygen stability and thermal stability of the material.

[0185] (II) Corresponding to the fabrication methods provided in Device Examples 1 and 5 to 8 above, single-electron devices (named Single-Electron Device 1, Single-Electron Device 5, Single-Electron Device 6, Single-Electron Device 7, and Single-Electron Device 8, respectively) were fabricated using the materials from Material Examples 1 and 5 to 8, and their current density-voltage curves were tested. The current densities of the devices at 5V were compared, and the results are shown in Table 2. The fabrication method of the single-electron device (EOD) is basically the same as that of its corresponding complete QLED device, the only difference being the removal of the hole injection layer and hole transport layer.

[0186] Table 2

[0187]

[0188] As shown in the table above, single-electron devices 1, 5, 6, 7, and 8 exhibit different current densities as the thickness of the shell in the ZnO@NaF material changes. This indicates that adjusting the thickness of the shell composed of alkali metal halides can regulate electron tunneling, thereby enhancing its electron injection capability.

[0189] (III) The devices prepared in the above-mentioned device embodiments and device comparison examples were subjected to performance testing. The results are recorded in Table 3. The test methods are as follows:

[0190] (1) External quantum dot efficiency:

[0191] 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:

[0192]

[0193] In the formula, η e For optical output coupling efficiency, η γ K represents the ratio of recombination carriers to injected carriers, x represents the ratio of excitons producing photons to the total number of excitons, and K represents the ratio of recombination carriers to injected carriers. R K is the radiation process rate. NR This represents the rate of a non-radiative process.

[0194] Test conditions: Conducted at room temperature with an air humidity of 30-60%.

[0195] (2) QLED device lifetime: The time required for the brightness of a device to decrease to a certain percentage of its maximum brightness under constant current or voltage driving. The time for the brightness to decrease to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the testing cycle, device lifetime testing is usually performed by accelerating device aging at high brightness, referencing OLED device testing, and the lifetime at high brightness is obtained by fitting the extended exponential decay brightness decay fitting formula. For example, the lifetime at 1000 nits is measured as T95. 1000nit The specific calculation formula is as follows:

[0196]

[0197] In the formula, T95 L For 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.

[0198] 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%.

[0199] Table 3

[0200] EQE max (%)]] [T95 1000nit (h)]]> Device Example 1 20.39 111.0 Device Example 2 16.59 51.0 Device Example 3 17.48 68.2 Device Example 4 20.02 101.2 Device Example 5 18.35 77.1 Device Example 6 16.62 56.6 Device Example 7 15.77 45.4 Device Example 8 15.27 33.9 Device Example 9 12.6 21.4 Device Example 10 17.11 56.3 Device Example 11 14.87 28.4 Device Comparative Example 1 13.17 2.8 Device Comparative Example 2 11.48 1.7

[0201] As can be seen from the table above:

[0202] Compared to Comparative Examples 1 and 2, Device Examples 1 to 11 in EQE max and T95 1000nit The significant improvement indicates that the use of the aforementioned composite material to fabricate the electron transport layer in this application is beneficial for improving the luminescence performance and lifespan of the device.

[0203] 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 composite material, characterized by, The metal oxide nanoparticles comprise one or more of undoped oxides and doped oxides; the undoped oxides comprise at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, the oxides in the doped oxides comprise at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, and the doping elements in the doped oxides comprise at least one of Al, Mg, Li, In, and Ga; and / or, 2. The composite material of claim 1, wherein, The alkali metal halide comprises an alkali metal fluoride, and the alkali metal fluoride comprises one or more of NaF, KF, LiF, RbF, CsF, and FrF. The alkali metal halide includes an alkali metal cation including one or more of Na + , K + , Li + , Rb + , Cs + , and Fr + , and a halide anion including one or more of F - , Cl - , Br - , and I - .

3. The composite material of claim 2, wherein, The metal oxide nanoparticles are ZnO nanoparticles, and the shell layer coated on the surface of the ZnO nanoparticles is a NaF shell layer.

4. The composite material of claim 3, wherein, The average particle size of the metal oxide nanoparticles is 3-12 nm; and / or, 5. The composite material according to any one of claims 1 to 4, characterized in that, The thickness of the shell layer is 0.3-5 nm; and / or, The average particle size of the composite material is 3.3-17 nm. The method comprises the following steps:

6. A method of producing a composite material, characterized by, Providing a mixed solution, wherein the mixed solution comprises metal oxide nanoparticles, an alkali metal halide, and an organic solvent; Performing heat treatment on the mixed solution to obtain a composite material. The molar ratio of the alkali metal halide to the metal element in the metal oxide nanoparticles is 1:2-4; and / or, 7. The production method according to claim 6, wherein The temperature of the heat treatment is 260-300°C; and / or, The time of the heat treatment is 60-90 min; and / or, The organic solvent comprises one or more of C8-C18 organic acids, preferably, the C8-C18 organic acids comprise one or more of octanoic acid, decanoic acid, heptanoic acid, oleic acid, stearic acid, dodecanoic acid, tetradecanoic acid, and hexadecanoic acid; and / or, The metal oxide nanoparticles comprise one or more of undoped oxides and doped oxides; the undoped oxides comprise at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, the oxides in the doped oxides comprise at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, and the doping elements in the doped oxides comprise at least one of Al, Mg, Li, In, and Ga; and / or, Before the step of providing a mixed solution, the preparation method further comprises a step of preparing the mixed solution, and the step of preparing the mixed solution comprises: The alkali metal halide includes an alkali metal cation including one or more of Na + , K + , Li + , Rb + , Cs + , and Fr + , and a halide anion including one or more of F - , Cl - , Br - , and I - .

8. The preparation method according to claim 6, characterized in that, Providing a metal precursor and a first solvent, mixing the metal precursor and the first solvent, and performing a first reaction to obtain a first mixture comprising an organometallic complex; Providing a second solvent, mixing the second solvent and the first mixture, and reacting to obtain a second mixture comprising metal oxide nanoparticles; The metal oxide nanoparticles comprise one or more of undoped oxides and doped oxides; the undoped oxides comprise at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, the oxides in the doped oxides comprise at least one of ZnO, TiO2, SnO2, Ga2O3, and Al2O3, and the doping elements in the doped oxides comprise at least one of Al, Mg, Li, In, and Ga; and / or, The alkali metal halide comprises an alkali metal fluoride, and the alkali metal fluoride comprises one or more of NaF, KF, LiF, RbF, CsF, and FrF. The metal oxide nanoparticles are ZnO nanoparticles, and the shell layer coated on the surface of the ZnO nanoparticles is a NaF shell layer. The average particle size of the metal oxide nanoparticles is 3-12 nm; and / or, The thickness of the shell layer is 0.3-5 nm; and / or, The average particle size of the composite material is 3.3-17 nm. The alkali metal halide and the organic solvent are provided, the second mixture, the alkali metal halide and the organic solvent are mixed to obtain a mixed solution containing metal oxide nanoparticles, alkali metal halide and organic solvent.

9. The production method according to claim 8, characterized by, The first solvent comprises one or more of octadecene, paraffin oil, tetrahydrofuran, disilicone oil, octafluorocyclohexane and polycyclopentadiene; and / or, The metal precursor comprises an organic acid salt containing a metal element, the metal element comprises at least one of Zn, Ti, Sn, Ga, Al, Mg, Li, In and Ga, and the organic acid radical in the organic acid salt comprises at least one of stearate, oleate, dodecylate, tetradecylate and hexadecylate; and / or, The step of mixing the metal precursor and the first solvent to perform the first reaction to obtain the first mixture comprises: mixing the metal precursor and the first solvent, performing vacuum extraction at a first temperature, and then performing the first reaction under an inert atmosphere at a second temperature, wherein the first temperature is 120-140°C, and the second temperature is 270-290°C; and / or, The molar ratio of the first solvent to the metal element in the metal precursor is 2.2-3:1; and / or, The second solvent comprises a mixed solution of an alcohol compound and an A solvent, the alcohol compound comprises one or more of C6-C18 alcohol compounds, the C6-C18 alcohol compounds comprise one or more of hexanol, octanol, dodecanol, tetradecanol, hexadecanol and octadecanol, and the A solvent comprises one or more of octadecene, paraffin oil, tetrahydrofuran, disilicone oil, octafluorocyclohexane and polycyclopentadiene; and / or, The step of mixing the second solvent and the first mixture to react to obtain the second mixture containing metal oxide nanoparticles comprises: mixing the second solvent and the first mixture to perform a second reaction to obtain a reaction mixture, providing a third solvent, mixing the third solvent and the reaction mixture to perform a third reaction to obtain a third mixture containing metal oxide nanoparticles; and / or, The molar ratio of the organic solvent to the first solvent is 1:1-1.

2.

10. The method of claim 9, wherein, The time for vacuum extraction is 25-60 min; and / or, The time for the first reaction is 25-60 min; and / or, The molar ratio of the alcohol compound in the second solvent to the metal element in the metal precursor is 1:0.15-0.25; and / or, The temperature for the second reaction is 240-260°C; and / or, The time for the second reaction is 5-10 min; and / or, The third solvent comprises a mixed solution of an acid compound and a B solvent, the acid compound comprises one or more of C8-C18 organic acids, the C8-C18 organic acids comprise one or more of octanoic acid, decanoic acid, heptanoic acid, oleic acid, stearic acid, dodecanoic acid, tetradecanoic acid and hexadecanoic acid, and the B solvent comprises one or more of octadecene, paraffin oil, tetrahydrofuran, disilicone oil, octafluorocyclohexane and polycyclopentadiene; and / or, the third reaction is at a temperature of 240-260°C; and / or, the third reaction is for a time of 60-90 min.

11. The method of claim 10, wherein, the molar ratio of the acid compound in the third solvent to the metal element in the metal precursor is 1:0.8-1.

12. A film, characterized by, the material of the thin film comprises the composite material of any one of claims 1-5, or, comprises the composite material prepared by the preparation method of any one of claims 6-11.

13. An optoelectronic device, characterized in that comprises an anode, an electron functional layer and a cathode arranged in a stack, the electron functional layer comprising the thin film of claim 12.

14. The optoelectronic device of claim 13, wherein, each of the anode and the cathode is independently selected from a doped metal oxide particle electrode, a metal and 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 and 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, 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 photoelectric device further comprises a light-emitting layer, which is arranged between the electron functional layer and the anode, and the material of the light-emitting layer comprises one or more of organic light-emitting materials and quantum dot light-emitting materials, wherein the organic light-emitting materials comprise one or more of 4,4'-bis(N-carbazole)-1,1'-biphenyl: tris[2-(p-tolyl)pyridine complex of iridium (III), 4,4',4"-tris(carbazole-9-yl)triphenylamine: tris[2-(p-tolyl)pyridine complex of iridium, diaryl anthracene derivative, stilbene aromatic derivative, pyrene derivative, fluorene derivative, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescent material, TTA material, thermally activated delayed material, polymer containing B-N covalent bond, hybrid local charge transfer excited state material, exciplex light-emitting material, and the quantum dot light-emitting materials comprise at least one of single-structure quantum dots, core-shell structure quantum dots and perovskite type semiconductor materials, wherein the shell layer of the core-shell structure quantum dots comprises 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 layer material of the core-shell structure quantum dots independently comprise at least one of II-VI group compound, IV-VI group compound, III-V group compound and I-III-VI group compound; the II-VI group compound comprises at least one of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe; and the IV-VI group compound comprises at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe.The III-V compound includes at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI compound includes at least one of CuInS2, CuInSe2, and AgInS2; the perovskite semiconductor material includes a doped or undoped inorganic perovskite semiconductor, or an organic-inorganic hybrid perovskite semiconductor; the inorganic perovskite semiconductor has a general structure of AMX3, where A is Cs; + ion, M is a divalent metal cation selected from at least one of Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ ; X is a halide anion selected from at least one of Cl - , Br - , I - ; the organic-inorganic hybrid perovskite semiconductor has a general structure of 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 at least one of Pb 2+ , Sn 2+ , Cu 2+ , Ni 2 + , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ at least one of Eu 2+ X is a halide anion selected from at least one of Cl - , Br - , I - .

15. A display device comprising: comprises the optoelectronic device of claim 13 or 14. comprises the optoelectronic device of claim 13 or 14.

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