Thin film preparation method, photoelectric device and electronic equipment

Abstract

The invention discloses a preparation method of a thin film, a photoelectric device and electronic equipment, and the method comprises the steps: providing a region to be subjected to film formation, the region to be subjected to film formation is composed of a central region and an edge region, and the edge region surrounds the central region; and in the environment with the electric field and / or the magnetic field, a solution containing a functional material is applied to the area where the film is to be formed, the functional material applied to the area where the film is to be formed moves towards the central area and / or deposits in the central area, the film is obtained, the functional material carries positive charges or negative charges, the film forming uniformity is improved, and the film forming efficiency is improved. The prepared film has good thickness uniformity; the preparation method of the film can be applied to preparation of a functional layer of a photoelectric device, and is beneficial to improving the photoelectric property of the photoelectric device and prolonging the service life of the device.

Description

Technical Field

[0001] The present application relates to the field of optoelectronic technologies, and particularly to a method for preparing a thin film, an optoelectronic device, and an electronic device. Background Art

[0002] In the field of optoelectronic technologies, solution methods are usually used to prepare functional thin films. The solution methods include, but are not limited to, inkjet printing, spin coating, screen printing, blade coating, dip coating, soaking, spraying, roll coating, or casting. These methods have the advantages of simple operation, high efficiency, and low preparation cost.

[0003] However, when using solution methods to prepare functional thin films, the "coffee ring" phenomenon is likely to occur. The reason for the "coffee ring" phenomenon is that the evaporation rate at the edge of the droplet is greater than that at the center, resulting in an outward capillary flow inside the droplet, which carries the suspended particles to the edge of the droplet and deposits them in a ring shape at the edge. The "coffee ring" phenomenon is particularly common in the preparation of functional thin films by inkjet printing. The "coffee ring" phenomenon will cause problems such as poor morphology and uneven thickness of the prepared functional thin films, thus having an adverse effect on the performance of the functional thin films.

[0004] Therefore, the uniformity of functional thin films still needs to be improved. Summary of the Invention

[0005] Based on this, the present application provides a method for preparing a thin film, an optoelectronic device, and an electronic device.

[0006] In a first aspect, the present application provides a method for preparing a thin film, including the following steps:

[0007] Providing a region to be formed into a film, where the region to be formed into a film is composed of a central region and an edge region, and the edge region surrounds the central region; and

[0008] In an environment with an electric field and / or a magnetic field, applying a solution including a functional material to the region to be formed into a film, and the functional material applied to the region to be formed into a film moves towards the central region and / or deposits on the central region to obtain a thin film;

[0009] Wherein, the functional material carries a positive charge or a negative charge.

[0010] In a second aspect, the present application provides an optoelectronic device, which includes:

[0011] A first electrode and a second electrode arranged oppositely; and

[0012] A functional layer disposed between the first electrode and the second electrode;

[0013] Wherein, the functional layer is prepared by using the method for preparing a thin film as described in the first aspect.

[0014] In a third aspect, the present application provides an electronic device, which includes the optoelectronic device as described in any one of the second aspect.

[0015] The present application provides a method for preparing a thin film, an optoelectronic device, and an electronic device, which have the following technical effects:

[0016] In the method for preparing the thin film, during the process of applying a solution including a functional material to a film-forming region to be formed, an electric field and / or a magnetic field is / are used to cause the functional material applied to the film-forming region to move toward the central region and / or deposit on the central region, suppressing the capillary flow of the edge flow, thereby effectively improving the "coffee ring" phenomenon, improving the film-forming uniformity, and enabling the obtained thin film to have good thickness uniformity; the method for preparing the thin film can be applied to prepare a functional layer of an optoelectronic device, which is beneficial to improving the optoelectronic performance and device life of the optoelectronic device. Description of the Drawings

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0018] Figure 1 It is a schematic flow chart of a method for preparing a thin film provided by an embodiment of the present application.

[0019] Figure 2 It is a schematic structural diagram of an optoelectronic device provided by an embodiment of the present application.

[0020] Figure 3 It is a schematic structural diagram of a film-forming region to be formed in Example 1 of the thin film.

[0021] Figure 4 It is a schematic diagram of the electric field distribution in step S1.2 in Example 1 of the thin film. Detailed Embodiments

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0023] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for illustrative purposes and cannot limit the content of the present application.

[0024] It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments. The various embodiments of the present application may exist in a range form; it should be understood that the description in a range form is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present invention; 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 considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the counted range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0025] The term "comprising" means "including but not limited to".

[0026] The term "at least one" means one or more, and "a plurality" means two or more. The term "at least one", "at least one of the following (items)" or similar expressions refer to any combination of these items, including any combination of single (item) or plural (items). For example, "at least one of (a, b, or c)" or "at least one of (a, b, and c)" can both be expressed as: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0027] The selection range of the term "and / or" includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The said any and all combinations include combinations of any two related listed items, any more related listed items, or all related listed items. For example, "A and / or B" includes three parallel solutions: A, B, and A + B. Another example, for the technical solution of "A, and / or, B, and / or, C, and / or, D", it includes any one of A, B, C, D (i.e., the technical solutions connected by "logical or"), and also includes any and all combinations of A, B, C, D, that is, it includes combinations of any two or any three of A, B, C, D, and also includes the four - item combination of A, B, C, D (i.e., the technical solutions connected by "logical and").

[0028] The term "particle size" refers to the diameter of the nanoparticles.

[0029] In the present application, descriptions such as "layer A is formed on one side of layer B", "layer A is formed on the side of layer B away from layer C", or similar descriptions can mean that layer A is directly formed on one side of layer B or on the side of layer B away from layer C, that is, layer A is in direct contact with layer B, or it can mean that layer A is indirectly formed on one side of layer B or on the side of layer B away from layer C, that is, other spacer structure layers can also be formed between layer A and layer B. Similarly, "layer A is disposed on one side of layer B", "layer A is disposed on the side of layer B away from layer C" can mean that layer A is in direct contact with layer B, or it can mean that other spacer structure layers are also provided between layer A and layer B; "layer A is disposed between layer B and layer C" can mean that layer A is in direct contact with layer B and layer A is in direct contact with layer C, or layer A is in direct contact with layer B and one or more spacer structure layers are provided between layer A and layer C, or one or more spacer structure layers are provided between layer A and layer B and one or more spacer structure layers are provided between layer A and layer C, or one or more spacer structure layers are provided between layer A and layer B and layer A is in direct contact with layer C.

[0030] In the present application, expressions such as "gradually decreasing", "gradually increasing", or similar expressions should be understood in a broad sense, which can be a gradient decrease (increase), or a linear continuous decrease (increase).

[0031] An embodiment of the present application provides a method for preparing a thin film, as Figure 1 shown, the method for preparing the thin film includes the following steps:

[0032] S1. Provide a film-forming region to be formed, the film-forming region to be formed is composed of a central region and an edge region, and the edge region surrounds the central region;

[0033] S2. In an environment with an electric field and / or a magnetic field, apply a solution including a functional material to the film-forming region to be formed, and the functional material applied to the film-forming region to be formed moves towards the central region and / or deposits on the central region to obtain a thin film.

[0034] In the method for preparing a thin film according to the embodiment of the present application, during the process of applying the solution including the functional material to the film-forming region to be formed, the functional material applied to the film-forming region to be formed is made to move towards the central region and / or deposit on the central region through an electric field and / or a magnetic field, suppressing the capillary flow of the edge flow, thereby effectively improving the "coffee ring" phenomenon, improving the film-forming uniformity, and making the obtained thin film have good thickness uniformity.

[0035] In step S1, the center point of the area to be film-formed is located in the central area. The area to be film-formed can be, for example, a single pixel area, and the pixel area is defined by a pixel definition layer. In some embodiments of the present application, the area of the central area accounts for 20% to 60% of the total area of the area to be film-formed, for example, it can be 20%, 30%, 40%, 50%, 60% or a value between any two of the foregoing percentage values; and / or, when the area to be film-formed is a single pixel area, the total area of the area to be film-formed is 10μm 2 ~10000μm 2 ,for example, it can be 10μm 2 、50μm 2 、100μm 2 、300μm 2 、500μm 2 、800μm 2 、1000μm 2 、2000μm 2 、3000μm 2 、4000μm 2 、5000μm 2 、6000μm 2 、7000μm 2 、8000μm 2 、9000μm 2 、10000μm 2 or a value between any two of the foregoing numerical values.

[0036] In some embodiments of the present application, for step S2, the environment has an electric field. The average electric field strength in the central area is the first electric field strength, and the average electric field strength in the edge area is the second electric field strength. The value of the first electric field strength is greater than the value of the second electric field strength, so that the functional material located in the edge area moves towards the central area, and this moving direction is opposite to the capillary flow direction, thereby improving the "coffee ring" phenomenon. It should be noted that the electric field strength in the central area can be a constant value, or along the straight line direction from the center point to any point on the edge of the central area, the electric field strength in the central area gradually decreases; similarly, the electric field strength in the edge area can be a constant value, or along the straight line direction from the center point to the edge of the area to be film-formed, the electric field strength in the edge area gradually decreases.

[0037] In some embodiments of the present application, the environment has a magnetic field. The average magnetic field intensity in the central region is the first magnetic field intensity, and the average magnetic field intensity in the edge region is the second magnetic field intensity. The value of the first magnetic field intensity is greater than the value of the second magnetic field intensity, so that the functional material located in the edge region moves towards the central region, and this moving direction is opposite to the capillary flow direction, thereby improving the "coffee ring" phenomenon. It should be noted that the magnetic field intensity in the central region can be a constant value, or along the straight line direction from the center point to any point on the edge of the central region, the magnetic field intensity in the central region gradually decreases; similarly, the magnetic field intensity in the edge region can be a constant value, or along the straight line direction from the center point to any point on the edge of the film-forming region to be formed, the magnetic field intensity in the edge region gradually decreases.

[0038] In order to further improve the film-forming uniformity of the thin film, in some embodiments of the present application, the environment has an electric field, and along the straight line direction from any point (such as the center point) in the central region to any point on the edge of the film-forming region to be formed, the value of the electric field intensity of the electric field gradually decreases; and / or, the environment has a magnetic field, and along the straight line direction from any point (such as the center point) in the central region to any point on the edge of the film-forming region to be formed, the value of the magnetic field intensity of the magnetic field gradually decreases, so as to have an electric field intensity corresponding to the capillary flow velocity in different regions, thereby continuously providing power for the moving functional material.

[0039] In order to achieve that along the straight line direction from the center point to any point on the edge of the film-forming region to be formed, the value of the electric field intensity of the electric field gradually decreases, in some embodiments of the present application, the environment has an electric field, the functional material carries a negative charge, and the electric field lines of the electric field in the film-forming region to be formed are radially divergent from the center point to any point on the edge of the film-forming region to be formed; or, the functional material carries a positive charge, and the electric field lines of the electric field in the film-forming region to be formed are radially convergent from any point on the edge of the film-forming region to be formed to the center point.

[0040] In order to improve the matching degree between the electric field strength and the capillary flow velocity in each region within the film-forming region to further suppress the capillary flow in the edge flow direction, in some embodiments of the present application, the environment has an electric field, and along the straight line direction from the center point to any point on the edge of the film-forming region, the value of the electric field strength of the electric field decreases in a gradient manner, and the gradient difference is 1 mV / μm to 100 mV / μm. The gradient difference can be 1 mV / μm, 5 mV / μm, 10 mV / μm, 20 mV / μm, 30 mV / μm, 40 mV / μm, 50 mV / μm, 60 mV / μm, 70 mV / μm, 80 mV / μm, 90 mV / μm, 100 mV / μm, or a value between any two of the foregoing values. Optionally, the difference between the value of the first electric field strength and the value of the second electric field strength is 10 mV / μm to 2000 mV / μm. For example, it can be 10 mV / μm, 50 mV / μm, 100 mV / μm, 500 mV / μm, 1000 mV / μm, 1500 mV / μm, 2000 mV / μm, or a value between any two of the foregoing values; and / or, the numerical distribution range of the electric field strength of the electric field in the film-forming region is 1 mV / μm to 5000 mV / μm.

[0041] In order to improve the matching degree between the magnetic field strength and the capillary flow velocity in each region within the film-forming region to further suppress the capillary flow in the edge flow direction, in some embodiments of the present application, the environment has a magnetic field, and along the straight line direction from the center point to any point on the edge of the film-forming region, the value of the magnetic field strength of the magnetic field decreases in a gradient manner, and the gradient difference is 1 mA / μm to 100 mA / μm. The gradient difference can be 1 mA / μm, 5 mA / μm, 10 mA / μm, 20 mA / μm, 30 mA / μm, 40 mA / μm, 50 mA / μm, 60 mA / μm, 70 mA / μm, 80 mA / μm, 90 mA / μm, 100 mA / μm, or a value between any two of the foregoing values. Optionally, the difference between the value of the first magnetic field strength and the value of the second magnetic field strength is 10 mA / μm to 2000 mA / μm. For example, it can be 10 mA / μm, 50 mA / μm, 100 mA / μm, 500 mA / μm, 1000 mA / μm, 1500 mA / μm, 2000 mA / μm, or a value between any two of the foregoing values; and / or, the numerical distribution range of the electric field strength of the electric field in the film-forming region is 1 mA / μm to 5000 mA / μm.

[0042] In step S2, the functional material carries a positive charge or a negative charge. The functional material is, for example, selected from inorganic nanoparticles, and the inorganic nanoparticles include, but are not limited to, one or more of metal oxide nanoparticles and luminescent quantum dots. The average particle size of the inorganic nanoparticles is, for example, 1 nm to 100 nm. It should be noted that those skilled in the art are aware of the operation process of making the functional material carry a positive charge or a negative charge. For example, the method of adsorbing charged groups on the surface of the functional material can be used. Among them, the charged groups include, but are not limited to, one or more of sulfate, phosphate, ammonium ion, and halogen ion. The charged groups can be derived from salt compounds, and the surface of the functional material can be treated with salt compounds. For another example, when the functional material is an inorganic nanoparticle, the operation process of making the functional material carry a positive charge or a negative charge can be achieved by connecting a specific ligand on the surface of the functional material. The specific ligand includes, but is not limited to, one or more of oleylamine, n-octanethiol, trioctylphosphine, PEG-COOH, polyethylene glycol, polysiloxane, polyvinylcarbazole, polyvinyl alcohol, dodecanethiol, benzenethiol, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, 1,2-ethanedithiol, 3-mercaptopropionic acid, oleic acid, 1,2-ethylenediamine, octylamine, tri-n-octylphosphine, tributylphosphine, and tetrabutylammonium fluoride.

[0043] In some embodiments of the present application, the inorganic nanoparticles carry a negative charge, and a first ligand is connected to the surface of the inorganic nanoparticles. The first ligand is selected from carboxyl or polyaliphatic carboxylic acid compounds. The polyaliphatic carboxylic acid compounds are, for example, selected from 1,3-propanedioic acid, 1,4-butanedioic acid, 1,5-pentanedioic acid, 1,6-hexanedioic acid, 1,7-heptanedioic acid; or the inorganic nanoparticles carry a positive charge, and a second ligand is connected to the surface of the inorganic nanoparticles. The second ligand is selected from tetrabutylammonium fluoride.

[0044] In step S2, the application method of the solution including the functional material includes but is not limited to one or more of spin coating method, printing method, inkjet printing method, blade coating method, printing method, dip coating method, immersion method, spraying method, roll coating method, casting method, slot die coating method and bar coating method. The solvent of the solution including the functional material includes but is not limited to one or more of alkanes, aromatic hydrocarbons, halogenated alkanes, alcohol compounds, ether compounds, furan compounds, pyridine compounds, amide compounds, ester compounds and sulfone compounds. It should be noted that when the solution including the functional material is ink, the boiling point of the solvent is not less than 150 °C, such as not less than 180 °C, not less than 200 °C, not less than 250 °C, not less than 275 °C or not less than 300 °C, and / or the surface tension of the solution including the functional material at the working temperature or at 25 °C ranges from 19 dyne / cm to 50 dyne / cm, and / or the viscosity of the solution including the functional material at the working temperature or 25 °C ranges from 1 cps to 100 cps, which is beneficial to prevent the "nozzle clogging" problem of the inkjet printing head and is beneficial to improving the film forming quality.

[0045] In order to balance improving the processing performance of the solution including the functional material and the density of the formed film, in some embodiments of the present application, in the solution, the concentration of the functional material is 5 mg / mL to 100 mg / mL, for example, it can be 5 mg / mL, 10 mg / mL, 30 mg / mL, 50 mg / mL, 80 mg / mL, 100 mg / mL or a value between any two of the foregoing values.

[0046] In order to obtain a cured film, in some embodiments of the present application, in step S2, after the step of applying the solution including the functional material to the area to be formed into a film and before the step of obtaining the thin film, the method for preparing the thin film further includes the step of removing the electric field and / or the magnetic field and drying the functional material solution deposited on the area to be formed into a film. Among them, the drying treatment includes but is not limited to one or more of natural air drying treatment, heat treatment, vacuum drying treatment, laser annealing treatment, electron beam annealing treatment, atomic annealing treatment and microwave irradiation annealing treatment.

[0047] The embodiments of the present application also provide an optoelectronic device, and the optoelectronic device includes but is not limited to a light emitting diode, a photovoltaic cell or a photodetector, such as Figure 2 As shown, the optoelectronic device 10 includes a first electrode 11, a second electrode 12 and a functional layer 13. The first electrode 11 and the second electrode 12 are arranged opposite to each other. One of the first electrode 11 and the second electrode 12 is an anode and the other is a cathode; the functional layer 13 is arranged between the first electrode 11 and the second electrode 12, and the functional layer 13 is prepared by using any one of the thin film preparation methods described above.

[0048] In the optoelectronic device 10 according to the embodiment of the present application, the functional layer 13 is prepared by using the preparation method of any one of the thin films described above, which improves the film formation quality of the functional layer 13, thereby improving the optoelectronic efficiency and device life of the optoelectronic device 10.

[0049] In some embodiments of the present application, the materials of the first electrode 11 and the second electrode 12 are independently selected from one or more of metals, carbon materials, and third metal oxides. Among them, the metals include, but are not limited to, one or more of Al, Ag, Cu, Mo, Au, Ba, Pt, Ca, Ir, Ni, and Mg. The carbon materials include, but are not limited to, one or more of graphite, carbon nanotubes, graphene, and carbon fibers. The third metal oxide can be doped or undoped. The doped third metal oxides include, but are not limited to, one or more of indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), and magnesium-doped zinc oxide (MZO). The undoped third metal oxides include, but are not limited to, one or more of TiO2, SnO2, ZnO, and In2O3.

[0050] It should be noted that the first electrode 11 and the second electrode 12 can also be composite electrodes respectively. The composite electrode has a structure similar to a "sandwich". The materials of the upper layer and the bottom layer are doped or undoped third metal oxides respectively, and the material of the middle layer is a metal. Examples include one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2. The average thicknesses of the first electrode 11 and the second electrode 12 are, for example, independently selected from 20 nm to 300 nm.

[0051] To further improve the comprehensive performance of the optoelectronic device 10, in some embodiments of the present application, continue to refer to Figure 2, the functional layer 13 includes a light-emitting layer 131, and the material of the light-emitting layer 131 includes one or more of an organic light-emitting material and light-emitting quantum dots. Among them, the organic light-emitting material includes, but is not limited to, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridineiridium(III), 4,4',4''-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridineiridium, diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, thermally activated delayed material, polymer containing B-N covalent bond, hybrid local charge transfer excited state material, exciplex luminescent material, polyacetylene and its derivatives, polyphenylene and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives, etc.

[0052] The light-emitting quantum dots include, but are not limited to, one or more of red quantum dots, green quantum dots, and blue quantum dots, and the light-emitting quantum dots include, but are not limited to, one or more of single-component quantum dots, core-shell structure quantum dots, inorganic perovskite quantum dots, organic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots. The average particle size of the light-emitting quantum dots can be 2 nm to 20 nm, for example, it can be 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 15 nm, 20 nm, or a value between any two of the foregoing values.

[0053] For single-component quantum dots and core-shell structured quantum dots, the material of the single-component quantum dots, the material of the core of the core-shell structured quantum dots, or the material of the shell of the core-shell structured quantum dots includes, but is not limited to, one or more of II-VI group compounds, III-V group compounds, III-VI group compounds, IV-VI group compounds, and I-III-VI group compounds. Among them, the II-VI group compounds are selected from one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the III-VI group compounds are selected from one or more of In2S3, In2Se3, InGaS3, and InGaSe3; the III-V group compounds are selected from one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the IV-VI group compounds are selected from one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the I-III-VI group compounds are selected from one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2.It should be noted that for the materials of the aforementioned single-component quantum dots, or the cores of core-shell quantum dots, or the shells of core-shell quantum dots, the chemical formulas provided 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 expressed, it corresponds to Cd. x Zn 1-x Se, 0 < x < 1.

[0054] For inorganic perovskite quantum dots, the general structural formula of inorganic perovskite quantum dots is AMX3, where A is Cs + , M is a divalent metal cation, and M includes but is not limited to Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ or Eu 2+ , X is a halogen anion, including but not limited to Cl - , Br - or I - .

[0055] For organic perovskite quantum dots, the general structural formula of organic perovskite quantum dots is CMX3, where C is formamidinium, M is a divalent metal cation, and M includes but is not limited to Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ or Eu 2+ , X is a halogen anion, including but not limited to Cl - , Br - or I - .

[0056] For organic-inorganic hybrid perovskite quantum dots, the general structural formula of organic-inorganic hybrid perovskite quantum dots is BMX3, where B is selected from organic amine cations, and organic amine cations include but are not limited to CH3(CH2) n-2 NH 3+ (n≥2) or NH3(CH2) nNH3 2+ (n≥2), M is a divalent metal cation, and M includes but is not limited to Pb 2+ 、Sn 2+ 、Cu 2+ 、Ni 2+ 、Cd 2+ 、Cr 2+ 、Mn 2+ 、Co 2+ 、Fe 2+ 、Ge 2+ 、Yb 2+ or Eu 2+ ,X is a halogen anion, including but not limited to Cl - 、Br - or I - 。

[0057] It should be noted that when the material of the light-emitting layer 131 includes light-emitting quantum dots, ligands can also be connected to the surface of the light-emitting quantum dots. The ligands include but are not limited to fatty carboxylic acid ligands with C1-C 30 , aromatic carboxylic acid ligands with C6-C 30 , fatty thiol ligands with C1-C 30 , thiol aromatic ligands with C6-C 30 , fatty amine ligands with C1-C 30 , aromatic amine ligands with C6-C 30 , fatty phosphine ligands with C1-C 30 , aromatic phosphine ligands with C6-C 30 , aromatic phosphate ligands with C6-C 30 and one or more of halogen ligands.

[0058] Among them, the fatty carboxylic acid ligands include but are not limited to one or more of caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, lignoceric acid, cerotic acid, oleic acid, linoleic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid; the aromatic carboxylic acid ligands include but are not limited to one or more of benzoic acid, biphenylcarboxylic acid, and 1-naphthoic acid. The fatty thiol ligands include but are not limited to one or more of hexanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol, hexadecanethiol, and octadecanethiol, and the aromatic thiol ligands include but are not limited to one or more of benzenethiol, triphenylmethanethiol, and p-terphenyl-4,4”-dithiol. The fatty amine ligands include but are not limited to one or more of hexylamine, octylamine, dioctylamine, trioctylamine, nonylamine, decylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, and oleylamine, and the aromatic amine ligands include but are not limited to one or more of aniline, indanylpropylamine, 4-octylaniline, and benzidine. The fatty phosphine ligands include but are not limited to one or more of trimethylphosphine, triethylphosphine, tripropylphosphine, tributylphosphine, trihexylphosphine, trioctylphosphine, tridecylphosphine, tributylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, and tridecylphosphine oxide, and the aromatic phosphine ligands include but are not limited to one or more of bis(2-diphenylphosphinoethyl)phenylphosphine and triphenylphosphine oxide. The aromatic phosphate ligands include but are not limited to one or more of tetraethyl p-xylene diphosphate and ethyl diphenyl phosphate. The halogen ligands include but are not limited to -Cl, -F, -I, or -Br.

[0059] In some embodiments of the present application, the light-emitting layer is prepared by the preparation method of any one of the thin films described above. Correspondingly, the functional material is selected from light-emitting quantum dots, and the solvent of the solution including the functional material is, for example, selected from one or more of diethylbenzene, mesitylene, propylbenzene, isopropylbenzene, p-cymene, butylbenzene, 1-methylnaphthalene, and indene.

[0060] In order to further improve the comprehensive performance of the optoelectronic device 10, the functional layer 13 includes an electron functional layer 132, and the electron functional layer 132 is disposed between the light-emitting layer 131 and the cathode, as Figure 2As shown, when the optoelectronic device 10 has an upright structure, the electron functional layer 132 is disposed between the light-emitting layer 131 and the second electrode 12; the average thickness of the electron functional layer 132 is, for example, 10 nm to 200 nm. The electron functional layer 132 may be a single-layer structure or a multi-layer structure; when the electron functional layer 132 is a multi-layer structure, the electron functional layer 132 includes, for example, one or more of an electron injection layer, an electron transport layer, and a hole blocking layer. For the electron functional layer 132 including an electron injection layer, an electron transport layer, and a hole blocking layer, the electron transport layer is located between the electron injection layer and the hole blocking layer, and the electron injection layer is closer to the cathode than the hole blocking layer, and the hole blocking layer is closer to the light-emitting layer 131 than the electron injection layer.

[0061] Among them, the electron functional layer 132 includes one or more of an undoped first inorganic compound and a doped second inorganic compound. Among them, the undoped first inorganic compound includes one or more of an undoped first metal oxide, a IIB-VIA group semiconductor material, a IIIA-VA group semiconductor material, and a IB-IIIA-VIA group semiconductor material. The undoped first metal oxide includes, but is not limited to, one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2, and / or the IIB-VIA group semiconductor material includes, but is not limited to, one or more of ZnS, ZnSe, and CdS, and / or the IIIA-VA group semiconductor material includes, but is not limited to, one or more of InP and GaP, and / or the IB-IIIA-VIA group semiconductor material includes, but is not limited to, one or more of CuInS and CuGaS.

[0062] The doped second inorganic compound includes a second metal oxide doped with a first doping element. The second metal oxide includes, but is not limited to, one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2. The first doping element includes, but is not limited to, one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn. The molar percentage of the first doping element in the doped second inorganic compound is, for example, not higher than 5%, not higher than 10%, not higher than 20%, not higher than 30%, or not higher than 50%. The doped second inorganic compound includes, but is not limited to, one or more of magnesium zinc oxide, calcium zinc oxide, zirconium zinc oxide, gallium zinc oxide, aluminum zinc oxide, lithium zinc oxide, titanium zinc oxide, yttrium zinc oxide, indium tin oxide, and lithium titanium oxide. Examples are Zn (1-x) Mg x O, Zn (1-x) Ca x O, Zn (1-x) Zr x O, Zn(1-x) Ga x O, Zn (1-x) Al x O, Zn (1-x) Li x O, Al (1-x) Zn x O, Zn (1-x) Ti x O, Zn (1-x) Y x O, In (1-x) Sn x O and Ti (1-x) Li x One or more of O, where 0 < x ≤ 0.5.

[0063] It should be noted that when the electronic functional layer 132 includes multiple materials and the electronic functional layer 132 is a multilayer structure, the multiple materials can all be in the same layer, or in different layers respectively, or some in the same layer. As an example, as Figures 1 to 4 shown, the electronic functional layer 132 is a single-layer structure, and the electronic functional layer 132 is an electron transport layer.

[0064] In some embodiments of the present application, the electronic functional layer 132 is prepared by the preparation method of any one of the thin films described above. Correspondingly, the functional material is selected from one or more of the non-doped first metal oxide and the doped second inorganic compound. The solvent of the solution including the functional material is, for example, selected from one or more of ethylene glycol, diethylene glycol, dipropylene glycol, and glycerol. It can be understood that when the electronic functional layer 132 is a multilayer structure, one layer, some layers, or all layers can be prepared by the preparation method of any one of the thin films described above.

[0065] In order to further improve the optoelectronic performance and device lifetime of the light-emitting device 1, in some embodiments of the present application, the functional layer 13 includes a hole functional layer 133. The hole functional layer 133 is disposed between the light-emitting layer 131 and the anode. As Figure 2 shown, when the optoelectronic device 10 is a normal structure, the hole functional layer 133 is disposed between the light-emitting layer 131 and the first electrode 11. The hole functional layer 133 can be a single-layer structure or a multilayer structure. The hole functional layer 133, for example, includes one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. For the hole functional layer 133 including a hole injection layer, a hole transport layer, and an electron blocking layer, the hole injection layer, the hole transport layer, and the electron blocking layer can be arranged in sequence, and the hole injection layer is closer to the anode than the electron blocking layer. The average thickness of the hole functional layer 133 is, for example, 10 nm to 200 nm.

[0066] Among them, the material of the hole functional layer 133 includes, but is not limited to, one or more of an undoped third inorganic compound, a doped fourth inorganic compound, and an organic compound. Among them, the organic compound includes, but is not limited to, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (abbreviation: PEDOT:PSS, CAS No. 155090-83-8), copper phthalocyanine (CAS No. 147-14-8), titanium oxyphthalocyanine (CAS No. 26201-32-1), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (CAS No. 29261-33-4), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (CAS No. 105598-27-4), polyaniline (CAS No. 25233-30-1), polypyrrole (CAS No. 30604-81-0), 3-hexyl-substituted polythiophene (CAS No. 104934-50-1), poly(9-vinylcarbazole) (abbreviation: PVK, CAS No. 25067-59-8), 4,4'-bis(9-carbazolyl)biphenyl (abbreviation: CBP, CAS No. 58328-31-7), poly[bis(4-phenyl)(4-butylphenyl)amine], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (abbreviation: TAPC, CAS No. 58473-78-2), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)] (abbreviation: TFB, CAS No. 220797-16-0), poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-ALT-(9,9-din-octylfluorene-2,7-diyl)] (CAS No. 223569-31-1), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (CAS No. 124729-98-2), 4,4',4''-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA, CAS No. 139092-78-7), 4,4',4'-tris(2-naphthylphenylamino)triphenylamine (CAS No. 185690-41-9), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (abbreviation: NPB, CAS No. 123847-85-8), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (abbreviation: TPD, CAS No. 65181-78-4), N,N'-bis[4-(diphenylamino)phenyl]-N,N'-diphenylbenzidine (CAS No. 209980-53-0), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-9,9-spirobifluorene-2,7-diamine (abbreviation: Spiro-TPD,One or more of 1033035-83-4), N2,N7-di-1-naphthyl-N2,N7-diphenyl-9,9'-spirobi[9H-fluorene]-2,7-diamine (CAS No. 932739-76-9), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (abbreviation: PTTA, CAS No. 1333317-99-9), and 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (abbreviation: Spiro-omeTAD, CAS No. 207739-72-8); and / or, the undoped third inorganic compound includes but is not limited to one or more of graphene, C60, nickel oxide (such as NiO), molybdenum oxide (such as MoO3), tungsten oxide (such as WO3), vanadium oxide (such as V2O5), p-type gallium nitride, chromium oxide (such as Cr2O3), copper oxide (such as CuO or Cu2O), copper sulfide (such as CuS), molybdenum sulfide (such as MoS2), and tungsten sulfide (such as WS2); and / or, the doped fourth inorganic compound is a host inorganic compound doped with a second doping element, and the host inorganic compound includes but is not limited to one or more of graphene, C60, nickel oxide (such as NiO), molybdenum oxide (such as MoO3), tungsten oxide (such as WO3), vanadium oxide (such as V2O5), p-type gallium nitride, chromium oxide (such as Cr2O3), copper oxide (such as CuO or Cu2O), copper sulfide (such as CuS), molybdenum sulfide (such as MoS2), and tungsten sulfide (such as WS2), and / or the second doping element includes but is not limited to one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metal elements.,

[0067] It can be understood that when the hole functional layer 133 includes multiple materials and the hole functional layer 133 is a multilayer structure, the multiple materials may all be in the same layer, or in different layers respectively, or partially in the same layer. For example, as Figures 2 to 4 shown, when the hole functional layer 133 is composed of a hole injection layer and a hole transport layer arranged in a stacked manner, the materials of the hole functional layer 133 include PEDOT:PSS and TFB, PEDOT:PSS and TFB are in different layers respectively, the material of the hole injection layer is PEDOT:PSS, and the material of the hole transport layer is TFB.

[0068] In some embodiments of the present application, the hole functional layer 133 is prepared by the preparation method of any one of the thin films described above. Correspondingly, the functional material is selected from one or more of the non-doped third inorganic compound and the doped fourth inorganic compound. The solvent of the solution including the functional material is, for example, selected from one or more of ethyl benzoate, propyl benzoate, butyl benzoate, ethyl phenylacetate, propyl phenylacetate, benzotrichloride, trichloroethylbenzene, dichlorotoluene, bromobenzene, and methylbromobenzene. It can be understood that when the hole functional layer 133 is a multi-layer structure, one layer, some layers, or all layers thereof can be prepared by the preparation method of any one of the thin films described above.

[0069] The embodiments of the present application also provide a preparation method of an optoelectronic device, which can be used to prepare any one of the foregoing optoelectronic devices. The preparation method of the optoelectronic device includes the following steps:

[0070] S1. Provide a first electrode and form a functional layer on one side of the first electrode;

[0071] S2. Form a second electrode on the side of the functional layer away from the first electrode.

[0072] Among them, one of the first electrode and the second electrode is an anode, and the other is a cathode; the formation method of the functional layer includes the steps of: sequentially forming a plurality of functional sub-layers on one side of the first electrode, and at least one functional sub-layer is prepared by the preparation method of any one of the thin films described above. In some embodiments of the present application, the functional layer includes, but is not limited to, one or more of an electron functional layer, a light-emitting layer, and a hole functional layer. The structural compositions of the electron functional layer, the light-emitting layer, and the hole functional layer all refer to the foregoing description.

[0073] In order to improve the binding tightness between adjacent functional sub-layers, in some embodiments of the present application, when two adjacent functional sub-layers are both prepared by the preparation method of any one of the thin films described above, the functional materials of the two adjacent functional sub-layers carry charges with opposite electricities respectively.

[0074] It should be noted that during the preparation of optoelectronic devices, in addition to the functional sub-layers obtained by using the preparation methods of any one of the thin films described above, the preparation methods of other functional sub-layers include, but are not limited to, chemical methods and / or physical methods. Among them, chemical methods include, but are not limited to, one or more of chemical vapor deposition, sequential ionic layer adsorption and reaction, anodic oxidation, electrodeposition, and coprecipitation. Physical methods include, but are not limited to, physical coating methods and solution methods. Physical coating methods include, but are not limited to, one or more of thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion coating, physical vapor deposition, atomic layer deposition, and pulsed laser deposition. Solution methods include, but are not limited to, one or more of spin coating, printing, inkjet printing, blade coating, printing, dip coating, immersion, spraying, roll coating, casting, slot die coating, and bar coating.

[0075] The embodiments of the present application also provide an electronic device, which includes any one of the optoelectronic devices described in the embodiments of the present application, or the electronic device includes an optoelectronic device obtained by using any one of the preparation methods described in the embodiments of the present application. The electronic device can be, for example, any electronic product with a display function, including but not limited to smartphones, tablet personal computers, mobile phones, video telephones, e-book readers, laptop PCs, netbook computers, workstations, servers, personal digital assistants, portable multimedia players, MP3 players, mobile medical devices, cameras, game consoles, digital cameras, in-vehicle navigators, electronic billboards, automated teller machines, smart bracelets, smart watches, Virtual Reality (VR) devices, or wearable devices.

[0076] The technical solutions and technical effects of the present application will be described in detail below through specific examples, comparative examples, and experimental examples. The following examples are only partial examples of the present application and do not specifically limit the present application.

[0077] Film Example 1

[0078] This example provides a method for preparing a film and the obtained film. The method for preparing the film includes the following steps:

[0079] S1.1. Provide a substrate including a film-forming region to be formed, as Figure 3 shown. The film-forming region to be formed 100 is circular and the total area of the film-forming region to be formed is 600 μm 2 . The film-forming region to be formed 100 is composed of a central region 101 and a peripheral region 102. The peripheral region surrounds the central region 101. The center point (center of the circle) of the film-forming region to be formed 100 is located in the central region 101. The central region 101 is circular (also with the center point as the center of the circle). The area of the central region 101 is 240 μm 2 . The peripheral region 102 is annular;

[0080] S1.2. Under an environment with an electric field, inkjet print 40 pL of a solution containing Zn 0.85 Mg 0.15 O nanoparticles (the concentration of Zn 0.85 Mg 0.15 O nanoparticles is 25 mg / mL, the average particle size of Zn 0.85 Mg 0.15 O nanoparticles is 5 nm, and the solvent is decanol) into the film-forming region to be formed. Among them, Zn 0.85 Mg 0.15 O nanoparticles carry negative charges. As Figure 4 shown, the electric field lines E in the film-forming region to be formed are radially divergent from any point on the edge of the central region 101 to any point on the outer edge of the peripheral region 102, and along the straight-line direction from any point on the edge of the central region 101 to any point on the outer edge of the peripheral region 102 (i.e., the radial direction of the film-forming region to be formed 100), the electric field strength value of the electric field decreases in a gradient manner, and the gradient difference is 20 mV / μm, so that the Zn 0.85 Mg 0.15 O nanoparticles inkjet-printed in the film-forming region to be formed 100 move towards the central region 101 or deposit on the central region 101 to obtain a wet film. The entire process of forming the wet film takes 5 minutes;

[0081] S1.3. Remove the electric field, and place the wet film prepared in step S1.2 in a nitrogen atmosphere environment with a pressure of 5×10 -4 Pa and a temperature of 150 °C for drying treatment to obtain a film including Zn 0.85 Mg 0.15 O nanoparticles. The average thickness of the film is 35.0 nm.

[0082] Among them, the preparation method of the solution containing Zn 0.85 Mg 0.15 O nanoparticles includes the following steps:

[0083] S1.11. Under the condition of introducing nitrogen, disperse 0.03 mol of zinc acetate dihydrate and 0.0045 mol of anhydrous magnesium acetate in 200 mL of N,N-dimethylformamide, and stir for 1 h to obtain a zinc source solution;

[0084] S1.12. Dissolve 0.06 mol of potassium hydroxide in 100 mL of ethanol, and stir for 1 h to obtain an alkali solution;

[0085] S1.13. Under the condition of introducing nitrogen, inject the alkali solution into the zinc source solution at an injection rate of 10 mL / min, and stir for 1 h for a mixing reaction. The mixing reaction is carried out at 30 °C to obtain a reaction solution;

[0086] S1.14. Add ethyl acetate to the reaction solution to form a precipitate, then centrifuge at 12000 r / min for 3 min, discard the supernatant and collect to obtain a first precipitate. Disperse the first precipitate in ethanol to obtain a first material solution; then, add ethyl acetate to the first material solution to form a precipitate, then centrifuge at 12000 r / min for 3 min, discard the supernatant and collect to obtain a second precipitate. Disperse the second precipitate in ethanol to obtain a second material solution; add ethanolamine (the volume ratio of the second material solution to ethanolamine is 3:1) to the second material solution and mix evenly, then add ethyl acetate until the solution turns slightly white, and then centrifuge at 12000 r / min for 3 min, discard the supernatant and collect to obtain a third precipitate. Disperse the third precipitate in ethanol to obtain a third material solution; dry the third material solution at 80 °C to remove the low-boiling alcohol solvent, and disperse the obtained solid in n-decanol to obtain a solution containing Zn 0.85 Mg 0.15 O nanoparticles.

[0087] It should be noted that the prepared Zn 0.85 Mg 0.15 O nanoparticles have rich carboxylic acid ligands (derived from zinc acetate dihydrate and anhydrous magnesium acetate) on their surfaces, making the Zn 0.85 Mg 0.15 O nanoparticles carry negative charges. In the up-down direction, the substrate is composed of a glass substrate, a first film layer, a second film layer, and a third film layer stacked in sequence. The thin film is formed on the side of the third film layer away from the second film layer. Among them, the material of the first film layer is PEDOT:PSS, and the average thickness of the first film layer is 85 nm; the material of the second film layer is TFB, and the average thickness of the second film layer is 40 nm; the material of the third film layer is CdSe / ZnS quantum dots, and the emission color is green. The average thickness of the third film layer is 20 nm, and the first film layer, the second film layer, and the third film layer are all prepared by inkjet printing.

[0088] Thin film Example 2

[0089] This example provides a method for preparing a thin film and the obtained thin film. Compared with the method for preparing the thin film in Example 1, the difference in the method for preparing the thin film in this example is only that: in step S1.2, "the gradient difference is 20 mV / μm" is replaced with "100 mV / μm", and the average thickness of the finally obtained thin film is 34.2 nm.

[0090] Thin film Example 3

[0091] This example provides a method for preparing a thin film and the obtained thin film. Compared with the method for preparing the thin film in Example 1, the difference in the method for preparing the thin film in this example is only that: in step S1.2, "the gradient difference is 20 mV / μm" is replaced with "1 mV / μm", and the average thickness of the finally obtained thin film is 35.5 nm.

[0092] Thin film Example 4

[0093] This example provides a method for preparing a thin film and the obtained thin film. The method for preparing the thin film includes the following steps:

[0094] S2.1 is the same as step S1.1;

[0095] S2.2. In an environment with an electric field, inkjet print 30 pL of a solution containing CdSe / ZnS quantum dots (the concentration of CdSe / ZnS quantum dots is 20 mg / mL, the average particle size of CdSe / ZnS quantum dots is 12 nm, and the solvent is β-caryophyllene) onto the area to be film-formed. Among them, the CdSe / ZnS quantum dots carry a positive charge, the emission color of the CdSe / ZnS quantum dots is green, the electric field lines in the area to be film-formed are radially convergent from any point on the edge of the area to be film-formed to the center point, and along the straight line direction from the center point to any point on the edge of the area to be film-formed (i.e., the radial direction of the area to be film-formed), the electric field intensity value of the electric field decreases in a gradient manner, and the gradient difference is 50 mV / μm, so that the CdSe / ZnS quantum dots inkjet printed onto the area to be film-formed move towards the central area or deposit in the central area to obtain a wet film, and the entire process of forming the wet film takes 5 min;

[0096] S2.3. Remove the electric field, and place the wet film obtained in step S2.2 in a nitrogen atmosphere environment with a pressure of 5×10 -4 Pa and a temperature of 150 °C for drying treatment to obtain a thin film including CdSe / ZnS quantum dots, and the average thickness of the thin film is 20.0 nm.

[0097] Among them, the method for preparing the solution containing CdSe / ZnS quantum dots includes the following steps:

[0098] S2.11. Place 0.4 mmol of cadmium oxide, 15 mL of stearic acid, 20 mL of trioctylphosphine oxide (TOPO), and 10 mL of N-hexadecylacrylamide (HAD) in a 100 mL three-necked flask, and then heat to 230 °C under an argon atmosphere until the cadmium oxide is completely dissolved. Naturally cool to room temperature to obtain a cadmium precursor; and, dissolve 0.4 mmol of selenium powder in 3 mL of trioctylphosphine under an argon atmosphere to obtain a selenium precursor;

[0099] S2.12. Under an argon atmosphere, inject 3 mL of the selenium precursor into the cadmium precursor, react at 230 °C for 1 h, and then cool to 180 °C to obtain a CdSe precursor;

[0100] S2.13. Dropwise add 3 mL of a zinc stearate-toluene solution (the concentration of zinc stearate is 4 mmol / mL) and 3 mL of a sulfur-tetrabutylammonium fluoride solution (the concentration of sulfur is 4 mmol / mL) to the CdSe precursor respectively. After reacting at 180 °C for 1 h, cool to 60 °C to obtain a reaction product;

[0101] S2.14. At room temperature, mix the reaction product of step 2.13 with 30 mL of ethanol to obtain a mixture, then centrifuge the mixture at a speed of 8000 r / min for 3 min. After discarding the supernatant, add 5 mL of n-hexane to redissolve and disperse the solid, then add 5 mL of ethanol, and centrifuge again at a speed of 8000 r / min for 3 min. Collect the precipitate, and disperse the collected precipitate in β-caryophyllene to obtain a solution containing CdSe / ZnS quantum dots.

[0102] It should be noted that the prepared CdSe / ZnS quantum dots have rich tetrabutylammonium fluoride ligands on their surfaces, making the CdSe / ZnS quantum dots carry positive charges. In the up-down direction, the substrate is composed of a glass substrate, a first film layer, and a second film layer stacked in sequence, and a thin film is formed on the side of the second film layer away from the first film layer, where the first film layer and the second film layer are the same as the corresponding film layers in Thin Film Example 1.

[0103] Thin Film Example 5

[0104] This example provides a method for preparing a thin film and the obtained thin film. The method for preparing the thin film includes the following steps:

[0105] S3.1. The same as step S1.1;

[0106] S3.2. Under an environment with an electric field, inkjet print 50 pL of a solution containing nickel oxide nanoparticles (the concentration of nickel oxide is 30 mg / mL, and the solvent is trichlorotoluene) onto the area to be film-formed. Among them, the nickel oxide nanoparticles carry negative charges. The electric field lines in the area to be film-formed are radially divergent from the center point to any point on the edge of the area to be film-formed, and along the straight-line direction from the center point to any point on the edge of the area to be film-formed (i.e., the radial direction of the area to be film-formed), the electric field intensity value of the electric field decreases in a gradient manner, and the gradient difference is 20 mV / μm, so that the nickel oxide nanoparticles inkjet-printed onto the area to be film-formed move towards the central area or deposit in the central area, obtaining a wet film. The entire process of forming the wet film takes 5 minutes;

[0107] S3.3. Remove the electric field, and place the wet film prepared in step S3.2 in a nitrogen atmosphere environment with a pressure of 5×10 -4 Pa and a temperature of 150 °C for drying treatment to obtain a thin film including nickel oxide nanoparticles. The average thickness of the thin film is 40.0 nm.

[0108] Among them, the preparation method of the solution containing nickel oxide nanoparticles includes the following steps:

[0109] S3.11. Under the condition of introducing nitrogen, ultrasonically dissolve and disperse 1 mol of nickel acetate tetrahydrate in 10 mL of ethylene glycol, and stir for 1 h to obtain a nickel acetate solution with a concentration of 0.1 mol / L;

[0110] S3.12. Take 0.5 mol of potassium hydroxide and dissolve it in 10 mL of ethanol, and stir for 1 h to obtain an alkali solution;

[0111] S3.13. Under the condition of introducing nitrogen, inject the alkali solution prepared in step S3.12 into the nickel acetate solution prepared in step S3.11 at an injection rate of 10 mL / min, and stir for 1 h for mixing reaction. The mixing reaction is carried out at 40 °C to obtain a reaction solution;

[0112] S3.14. Add ethyl acetate to the reaction solution to form a precipitate, then centrifuge at 8000 r / min for 3 min, discard the supernatant and collect the first precipitate. Disperse the first precipitate in ethanol to obtain the first material solution. Then, add ethyl acetate to the first material solution to form a precipitate, then centrifuge at 10000 r / min for 3 min, discard the supernatant and collect the second precipitate. Disperse the second precipitate in ethanol to obtain the second material solution. Add ethanolamine (the volume ratio of the second material solution to ethanolamine is 5:1) to the second material solution and mix well, then add ethyl acetate until the solution turns slightly white, and then centrifuge at 10000 r / min for 3 min. Discard the supernatant and collect the third precipitate. Disperse the third precipitate in ethanol to obtain the third material solution. Dry the third material solution at 80 °C to remove the low-boiling alcohol solvent, and disperse the obtained solid in trichlorotoluene to obtain a solution containing nickel oxide nanoparticles.

[0113] It should be noted that the surface of the prepared nickel oxide nanoparticles contains abundant carboxylic acid ligands (derived from nickel acetate tetrahydrate), making the nickel oxide nanoparticles carry negative charges. In the up-down direction, the substrate consists of a glass substrate and a first film layer stacked in sequence, and the thin film is formed on the side of the first film layer away from the substrate. Among them, the first film layer is the same as the first film layer in Thin Film Example 1.

[0114] Thin Film Comparative Example 1

[0115] This comparative example provides a method for preparing a thin film and the obtained thin film. The method for preparing the thin film includes the following steps:

[0116] S11.1. The same as step S1.1;

[0117] S11.2. Inkjet print 40 pL of a solution containing Zn 0.85 Mg 0.15 O nanoparticles (the same as the solution containing Zn 0.85 Mg 0.15 O nanoparticles in Thin Film Example 1) to the area to be formed into a film to obtain a wet film. The entire process of forming the wet film takes 5 min;

[0118] S11.3. Place the wet film prepared in step S1.2 in a nitrogen atmosphere environment with a pressure of 5×10 -4 Pa and a temperature of 150 °C for drying treatment to obtain a thin film including Zn 0.85 Mg 0.15 O nanoparticles. The average thickness of the thin film is 35.0 nm.

[0119] Thin Film Comparative Example 2

[0120] This comparative example provides a method for preparing a thin film and the obtained thin film. The method for preparing the thin film includes the following steps:

[0121] S12.1: The same as step S1.1;

[0122] S12.2: Inkjet print 40 pL of a solution containing CdSe / ZnS quantum dots (the same as the solution containing CdSe / ZnS quantum dots in Thin Film Example 4) onto the area to be formed into a film to obtain a wet film. The entire process of forming the wet film takes 5 minutes;

[0123] S12.3: Place the wet film obtained in step S12.2 in a nitrogen atmosphere environment with a pressure of 5×10 -4 Pa and a temperature of 150 °C for drying treatment to obtain a thin film including CdSe / ZnS quantum dots. The average thickness of the thin film is 20.0 nm.

[0124] Thin Film Comparative Example 3

[0125] This comparative example provides a method for preparing a thin film and the obtained thin film. The method for preparing the thin film includes the following steps:

[0126] S13.1: The same as step S1.1;

[0127] S13.2: Inkjet print 50 pL of a solution containing nickel oxide nanoparticles (the same as the solution containing nickel oxide nanoparticles in Thin Film Example 5) onto the area to be formed into a film to obtain a wet film. The entire process of forming the wet film takes 5 minutes;

[0128] S13.3: Place the wet film obtained in step S12.2 in a nitrogen atmosphere environment with a pressure of 5×10 -4 Pa and a temperature of 150 °C for drying treatment to obtain a thin film including nickel oxide nanoparticles. The average thickness of the thin film is 40.0 nm.

[0129] Thin film experimental examples: The thickness uniformity of the thin films prepared in Thin film Example 1 to Thin film Example 5 and Thin film Comparative Example 1 to Thin film Comparative Example 3 was tested. The testing method includes the steps: setting the target thickness of the thin film prepared by the inkjet printing method as D. For the thin film actually prepared by the inkjet printing method, within the entire film-forming area, if the printed thin film thickness is D ± 5 nm, it is regarded as meeting the requirements. Detect the percentage (S, %) of the area of the thin film with a thickness of D ± 5 nm in the entire film-forming area in the total area of the entire film-forming area. The larger S is, the better the thickness uniformity of the thin film represents, and the weaker the "coffee ring" effect corresponds. Among them, the target thickness of the thin films prepared by the inkjet printing method in Thin film Example 1 to Thin film Example 3 and Thin film Comparative Example 1 is 35.0 nm, the target thickness of the thin films prepared by the inkjet printing method in Thin film Example 4 and Thin film Comparative Example 2 is 20.0 nm, and the target thickness of the thin films prepared by the inkjet printing method in Thin film Example 5 and Thin film Comparative Example 3 is 40.0 nm. The test results are shown in Table 1 below:

[0130] Table 1

[0131]

[0132] As can be seen from Table 1, compared with Thin film Comparative Example 1, the thickness uniformity of the thin films in Thin film Example 1 to Thin film Example 3 is better; compared with Thin film Comparative Example 2, the thickness uniformity of the thin film in Thin film Example 4 is better; compared with Thin film Comparative Example 3, the thickness uniformity of the thin film in Thin film Example 5 is better.

[0133] This shows that by using the method for preparing a thin film in the embodiment of the present application to prepare a thin film, the functional material applied to the area to be formed into a film is moved toward the central area or deposited in the central area through an electric field and / or a magnetic field, suppressing the capillary flow of the edge flow, thereby effectively improving the "coffee ring" phenomenon and improving the uniformity of film formation.

[0134] Device Example 1

[0135] This embodiment provides an optoelectronic device and a preparation method thereof. The light-emitting device is a quantum dot light-emitting diode with a top-emitting structure. As Figure 2 shown, in the direction from bottom to top, the optoelectronic device 10 includes a first electrode 11, a hole functional layer 133, a light-emitting layer 131, an electron functional layer 132, and a second electrode 12 that are sequentially stacked. Among them, the first electrode 11 is an anode and the second electrode 12 is a cathode. The hole functional layer 133 is composed of a hole injection layer 1331 and a hole transport layer 1332 that are stacked. The hole injection layer 1331 is closer to the first electrode 11 than the hole transport layer 1332.

[0136] The materials and average thicknesses of each layer in the optoelectronic device 10 are as follows:

[0137] The material of the first electrode 11 is ITO, and the average thickness of the first electrode 11 is 10 nm;

[0138] The material of the second electrode 12 is Ag, and the average thickness of the second electrode 12 is 30 nm;

[0139] The material of the light-emitting layer 131 is CdSe / ZnS quantum dots, the emission color is green, the average thickness of the light-emitting layer 131 is 20 nm, and the total area of the light-emitting region is 600 μm 2 ;

[0140] The material of the electron functional layer 132 is Zn 0.85 Mg 0.15 O, and the average thickness is 35 nm;

[0141] The material of the hole injection layer 1331 is PEDOT:PSS, and the average thickness of the hole injection layer 1331 is 85 nm;

[0142] The material of the hole transport layer 1332 is TFB, and the average thickness of the hole transport layer 1332 is 40 nm.

[0143] The preparation method of the light-emitting device in this embodiment includes the following steps:

[0144] S10.1. Provide a substrate, sputter ITO on one side of the substrate to obtain an ITO layer, wipe the surface of the ITO layer with a cotton swab dipped in a small amount of soapy water to remove visible impurities on the surface, and then ultrasonically clean the substrate including ITO in deionized water for 15 min, acetone for 15 min, ethanol for 15 min, and isopropanol for 15 min in sequence. After drying, perform ultraviolet-ozone surface treatment for 20 min to obtain a substrate including the first electrode;

[0145] S10.2. Under the air environment of normal temperature and pressure, ink-jet print an aqueous solution of PEDOT:PSS with a mass fraction of 2.8% on the side of the first electrode away from the substrate, and then place it in a constant temperature heat treatment at 150 °C to cure into a film to obtain a hole injection layer;

[0146] S10.3. Under the nitrogen environment of normal temperature and pressure, ink-jet print a TFB-trichlorotoluene solution with a concentration of 8 mg / mL on the side of the hole injection layer away from the first electrode, and then place it in a constant temperature heat treatment at 150 °C to cure into a film to obtain a hole transport layer;

[0147] S10.4. Under the nitrogen environment of normal temperature and pressure, form a light-emitting layer on the side of the hole transport layer away from the hole injection layer by referring to the preparation method of the film in Film Comparative Example 2;

[0148] S10.5. Under a nitrogen environment at normal temperature and pressure, an electron functional layer is formed on the side of the light-emitting layer away from the hole transport layer with reference to the preparation method of the thin film in Thin Film Example 1.

[0149] S10.6. Place the stacked structure completed in Step S10.5 into an evaporation chamber with a vacuum degree not higher than 3×10 -4 Pa, thermally evaporate Ag on the side of the electron functional layer away from the light-emitting layer through a mask plate to obtain a second electrode, and then encapsulate to obtain an optoelectronic device.

[0150] Device Example 2

[0151] This example provides an optoelectronic device and its preparation method. Compared with the preparation method of the optoelectronic device in Device Example 1, the difference in the preparation method of the optoelectronic device in this example is that Step S10.5 is replaced with "Under a nitrogen environment at normal temperature and pressure, an electron functional layer is formed on the side of the light-emitting layer away from the hole transport layer with reference to the preparation method of the thin film in Thin Film Example 2".

[0152] Device Example 3

[0153] This example provides an optoelectronic device and its preparation method. Compared with the preparation method of the optoelectronic device in Device Example 1, the difference in the preparation method of the optoelectronic device in this example is that Step S10.5 is replaced with "Under a nitrogen environment at normal temperature and pressure, an electron functional layer is formed on the side of the light-emitting layer away from the hole transport layer with reference to the preparation method of the thin film in Thin Film Example 3".

[0154] Device Example 4

[0155] This example provides an optoelectronic device and its preparation method. Compared with the preparation method of the optoelectronic device in Device Example 1, the difference in the preparation method of the optoelectronic device in this example is that Step S10.4 is replaced with "Under a nitrogen environment at normal temperature and pressure, a light-emitting layer is formed on the side of the hole transport layer away from the hole injection layer with reference to the preparation method of the thin film in Thin Film Example 4".

[0156] Device Example 5

[0157] This example provides an optoelectronic device and its preparation method. Compared with the preparation method of the optoelectronic device in Device Example 1, the difference in the preparation method of the optoelectronic device in this example is that Step S10.4 is replaced with "Under a nitrogen environment at normal temperature and pressure, a light-emitting layer is formed on the side of the hole transport layer away from the hole injection layer with reference to the preparation method of the thin film in Thin Film Example 4", and Step S10.5 is replaced with "Under a nitrogen environment at normal temperature and pressure, an electron functional layer is formed on the side of the light-emitting layer away from the hole transport layer with reference to the preparation method of the thin film in Thin Film Comparative Example 1".

[0158] Device Embodiment 6

[0159] This embodiment provides an optoelectronic device and a preparation method thereof. Compared with the optoelectronic device in Device Embodiment 1, the difference of the optoelectronic device in this embodiment is that: the material of the hole transport layer is replaced with nickel oxide nanoparticles.

[0160] Compared with the preparation method of the optoelectronic device in Device Embodiment 1, the difference of the preparation method of the optoelectronic device in this embodiment is that: step S10.3 is replaced with "in a nitrogen environment at normal temperature and pressure, referring to the preparation method of the film in Film Embodiment 5, form a hole transport layer on the side of the hole injection layer away from the first electrode", and step S10.5 is replaced with "in a nitrogen environment at normal temperature and pressure, referring to the preparation method of the film in Film Comparative Example 1, form an electron functional layer on the side of the light-emitting layer away from the hole transport layer".

[0161] Device Comparative Example 1

[0162] This comparative example provides an optoelectronic device and a preparation method thereof. Compared with the preparation method of the optoelectronic device in Device Embodiment 1, the difference of the preparation method of the optoelectronic device in this comparative example is that: step S10.5 is replaced with "in a nitrogen environment at normal temperature and pressure, referring to the preparation method of the film in Film Comparative Example 1, form an electron functional layer on the side of the light-emitting layer away from the hole transport layer".

[0163] Device Comparative Example 2

[0164] This comparative example provides an optoelectronic device and a preparation method thereof. Compared with the preparation method of the optoelectronic device in Device Embodiment 1, the difference of the preparation method of the optoelectronic device in this comparative example is that: step S10.3 is replaced with "in a nitrogen environment at normal temperature and pressure, referring to the preparation method of the film in Film Comparative Example 3, form a hole transport layer on the side of the hole injection layer away from the first electrode".

[0165] Experimental Example

[0166] Performance tests were carried out on the optoelectronic devices completed in Device Examples 1 to Device Example 6, as well as Device Comparative Example 1 and Device Comparative Example 2. A FushiDa FPD optical property measurement device (including Ocean Optics USB2000, LabView-controlled QE-PRO spectrometer, Keithley 2400, high-precision digital source meter Keithley 6485, optical fiber with an inner diameter of 50 μm, device test probes and fixtures, various related connecting wires and data cards, efficiency test dark box and data acquisition system, etc.) was used to detect parameters such as the turn-on voltage, current, brightness, and emission spectrum of each optoelectronic device. Then, key parameters such as external quantum efficiency and power efficiency were calculated, and the device lifetimes of the above-mentioned optoelectronic devices were tested using a lifetime test device. The test environmental temperature was 25°C and the air humidity was 40%.

[0167] Among them, the test method for current efficiency is as follows: Set the luminous area to 2 mm × 2 mm = 4 mm 2 , discontinuously collect the brightness values of the light-emitting device within the range of turn-on voltage from 0 V to 8 V. The initial voltage value for collecting brightness is 3 V, and it is collected every 0.2 V. The brightness value collected each time is divided by the corresponding current density to obtain the current efficiency of the light-emitting device under the collection conditions of that time, and the maximum current efficiency (C.E max , cd / A) is obtained.

[0168] The detection method for device lifetime includes the steps: Under the drive of a constant current (2 mA), use a lifetime test device to perform electroluminescence lifetime analysis on each light-emitting device, record the time required for each light-emitting device to decay from the maximum brightness to 95%, and calculate the time required for each single-hole device to decay from 100% to 95% at a brightness of 1000 nit (T95@1000 nit, h) through the decay fitting formula.

[0169] The performance test data of each light-emitting device are shown in Table 2 below:

[0170] Table 2

[0171]

[0172] As can be seen from Table 2, compared with Device Comparative Example 1, the optoelectronic performance and device lifetime of the optoelectronic devices in Device Examples 1 to Device Example 5 are better. Taking the optoelectronic devices in Device Example 4 and Device Comparative Example 1 as an example, the C.E of the optoelectronic device in Device Example 4 max is the C.E of the optoelectronic device in Device Comparative Example 1 max1.7 times that of, and the T95@1000nit of the optoelectronic device in Device Example 4 is twice that of the optoelectronic device in Device Comparative Example 1. In addition, compared with Device Comparative Example 2, the optoelectronic device in Device Example 6 has better optoelectronic performance and device life.

[0173] It can be seen from this that when at least one functional sub-layer of the optoelectronic device is prepared by the film preparation method in the embodiments of the present application, the film formation quality of the functional layer can be improved, thereby improving the optoelectronic efficiency and device life of the optoelectronic device.

[0174] The above has introduced in detail a film preparation method, an optoelectronic device, and an electronic device provided by the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a thin film, characterized in that, The method includes the following steps: Providing a film-forming region to be formed, the film-forming region to be formed being composed of a central region and an edge region, the edge region surrounding the central region; And In an environment with an electric field and / or a magnetic field, applying a solution including a functional material to the film-forming region to be formed, and the functional material applied to the film-forming region to be formed moves toward the central region and / or deposits on the central region to obtain a thin film; Wherein, the functional material carries a positive charge or a negative charge.

2. The preparation method of the thin film according to claim 1, characterized in that, The environment has an electric field, the average electric field intensity of the central region is a first electric field intensity, the average electric field intensity of the edge region is a second electric field intensity, and the value of the first electric field intensity is greater than the value of the second electric field intensity; and / or The environment has a magnetic field, the average magnetic field intensity of the central region is a first magnetic field intensity, the average magnetic field intensity of the edge region is a second magnetic field intensity, and the value of the first magnetic field intensity is greater than the value of the second magnetic field intensity. After the step of applying the solution including the functional material to the film-forming region to be formed and before the step of obtaining the thin film, the method for preparing the thin film further includes the step of drying the functional material solution deposited on the film-forming region to be formed; And / or The functional material is selected from inorganic nanoparticles; And / or The solvent of the solution including the functional material is selected from one or more of alkanes, aromatic hydrocarbons, halogenated alkanes, alcohol compounds, ether compounds, furan compounds, pyridine compounds, amide compounds, and sulfone compounds; and / or In the solution including the functional material, the concentration of the functional material is 5 mg / mL to 100 mg / mL; and / or The film-forming region to be formed is a single pixel region; And / or The area of the central region accounts for 20% to 60% of the total area of the film-forming region to be formed; and / or The center point of the film-forming region to be formed is located in the central region.

3. The preparation method of the thin film according to claim 2, characterized in that, The average particle size of the inorganic nanoparticles is 1 nm to 100 nm; and / or The inorganic nanoparticles are selected from one or more of metal oxide nanoparticles and luminescent quantum dots; and / or The alkanes are selected from one or more of nonane, decane, dodecane, terpane, butylcyclohexane, n-octane, n-hexane, n-heptane, n-nonane, n-decane, cyclohexane, and cyclopentane, and / or the aromatic hydrocarbons are selected from one or more of diethylbenzene, trimethylbenzene, propylbenzene, isopropylbenzene, p-tolylisopropylbenzene, butylbenzene, and 1-methylnaphthalene or indene, and / or the halogenated alkanes are selected from one or more of dichloromethane, chloroform, and carbon tetrachloride, and / or the alcohol compounds are selected from one or more of methanol, ethanol, propanol, butanol, ethylene glycol, and glycerol, and / or the ether compound is selected from ethylene glycol monomethyl ether, and / or the furan compound is selected from tetrahydrofuran, and / or the pyridine compound is selected from pyridine, and / or the amide compound is selected from N,N-dimethylformamide, and / or the sulfone compound is selected from dimethyl sulfoxide; and / or The inorganic nanoparticles carry negative charges, and a first ligand is connected to the surface of the inorganic nanoparticles. The first ligand is selected from carboxyl or polyaliphatic carboxylic acid compounds; or, the inorganic nanoparticles carry positive charges, and a second ligand is connected to the surface of the inorganic nanoparticles. The second ligand is selected from tetrabutylammonium fluoride; and / or The total area of the region to be film-formed is 10 μm 2 to 10,000 μm 2 .

4. The preparation method of the thin film according to claim 2, characterized in that, The environment has an electric field; along the straight line direction from any point in the central region to any point on the edge of the film-forming region to be formed, the value of the electric field strength of the electric field gradually decreases; and / or The environment has a magnetic field; along the straight line direction from any point in the central region to any point on the edge of the film-forming region to be formed, the value of the magnetic field strength of the magnetic field gradually decreases.

5. The preparation method of the thin film according to claim 4, characterized in that, Along the straight line direction from the central point to any point on the edge of the film-forming region to be formed, the value of the electric field strength of the electric field gradually decreases; and / or Along the straight line direction from any point in the central region to any point on the edge of the film-forming region to be formed, the value of the electric field strength of the electric field decreases in a gradient manner, and the gradient difference is 1 mV / μm to 100 mV / μm; and / or Along the straight line direction from the central point to any point on the edge of the film-forming region to be formed, the value of the magnetic field strength of the magnetic field gradually decreases; Along the straight line direction from any point in the central region to any point on the edge of the film-forming region to be formed, the value of the magnetic field strength of the magnetic field decreases in a gradient manner, and the gradient difference is 1 mA / μm to 100 mA / μm.

6. The method for preparing the thin film according to claim 2, characterized in that, The environment has an electric field; the functional material carries negative charges, and the electric field lines of the electric field in the film-forming region to be formed are radially divergent from the central point to the edge of the film-forming region; or, the functional material carries positive charges, and the electric field lines of the electric field in the film-forming region to be formed are radially convergent from the edge of the film-forming region to the central point.

7. The method for preparing the thin film according to any one of claims 2 to 6, characterized in that, The environment has an electric field, and the difference between the values of the first electric field strength and the second electric field strength is 10 mV / μm to 2000 mV / μm, and / or the numerical distribution range of the electric field strength of the electric field in the film-forming region to be formed is 1 mV / μm to 5000 mV / μm; and / or The environment has a magnetic field, and the difference between the values of the first magnetic field strength and the second magnetic field strength is 10 mA / μm to 2000 mA / μm, and / or the numerical distribution range of the magnetic field strength of the magnetic field in the film-forming region to be formed is 1 mA / μm to 5000 mA / μm.

8. An optoelectronic device, characterized in that, The optoelectronic device includes: A first electrode and a second electrode disposed opposite to each other; and A functional layer disposed between the first electrode and the second electrode; Wherein, the functional layer is prepared by the preparation method of the thin film described in any one of claims 1 to 7.

9. The optoelectronic device according to claim 8, characterized in that, The functional layer includes an electronic functional layer, which is prepared by the preparation method of the thin film described in any one of claims 1 to 7. The functional material is selected from one or more of an undoped first inorganic compound and a doped second inorganic compound. Optionally, the undoped first inorganic compound includes one or more of an undoped first metal oxide, a IIB-VIA group semiconductor material, a IIIA-VA group semiconductor material, and a IB-IIIA-VIA group semiconductor material. The undoped first metal oxide includes one or more of ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, and ZrO2, and / or the IIB-VIA group semiconductor material includes one or more of ZnS, ZnSe, and CdS, and / or the IIIA-VA group semiconductor material includes one or more of InP and GaP, and / or the IB-IIIA-VIA group semiconductor material includes one or more of CuInS and CuGaS. Optionally, the doped second inorganic compound includes a second metal oxide doped with a first doping element. The second metal oxide is selected from ZnO, TiO2, SnO2, BaO, Ta2O3, Al2O3, or ZrO2. The first doping element is selected from one or more of Mg, Ca, Zr, W, Ga, Li, Al, Ti, Y, In, and Sn; and / or The functional layer includes a hole functional layer, which is prepared by the preparation method of the thin film described in any one of claims 1 to 7. The functional material is selected from one or more of an undoped third inorganic compound and a doped fourth inorganic compound. Optionally, the undoped third inorganic compound is selected from one or more of nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide. Optionally, the doped fourth inorganic compound is a host inorganic compound doped with a second doping element. The host compound is selected from one or more of nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, p-type gallium nitride, chromium oxide, copper oxide, copper sulfide, molybdenum sulfide, and tungsten sulfide, and / or the second doping element is selected from one or more of nickel, molybdenum, tungsten, vanadium, chromium, copper, and platinum group metal elements; and / or The functional layer includes a light-emitting layer, and the light-emitting layer is prepared by the preparation method of the thin film described in any one of claims 1 to 7. The functional material is selected from light-emitting quantum dots; optionally, the light-emitting quantum dots are selected from one or more of single-component quantum dots, core-shell structure quantum dots, inorganic perovskite quantum dots, organic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots;The material of the single-component quantum dots, the material of the core of the core-shell structure quantum dots, and the material of the shell of the core-shell structure quantum dots are independently selected from one or more of II-VI group compounds, III-V group compounds, III-VI group compounds, IV-VI group compounds, and I-III-VI group compounds. The shell layer of the core-shell structure quantum dots is one or more layers. Among them, the II-VI group compounds are selected from one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, MgS, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the III-VI group compounds are selected from one or more of In2S3, In2Se3, InGaS3, and InGaSe3; the III-V group compounds are selected from one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the IV-VI group compounds are selected from one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the I-III-VI group compounds are selected from one or more of AgInS, AgInS2, CuInS, CuInS2, AgGaS2, CuGaS2, CuGaO2, AgGaO2, AgAlO2, AgInGaS2, and CuInGaS2;And / or, the structural general formula of the inorganic perovskite quantum dots is AMX3, where A is Cs; + , M is a divalent metal cation, and M is selected from Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , and Eu 2+ one or more of them, X is a halogen anion; and / or, the structural general formula of the organic perovskite quantum dots is CMX3, C is formamidinium; and / or, the structural general formula of the organic-inorganic hybrid perovskite quantum dots is BMX3, B is an organic amine cation; and / or The materials of the first electrode and the second electrode are independently selected from one or more of a metal, a carbon material, and a third metal oxide, wherein the metal is selected from one or more of Al, Ag, Cu, Mo, Au, Ba, Pt, Ca, Ir, Ni, and Mg, and / or the carbon material is selected from one or more of graphite, carbon nanotubes, graphene, and carbon fibers, and / or the third metal oxide 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, aluminum-doped magnesium oxide, SnO2, ZnO, and In2O3.

10. An electronic device, characterized in that, The electronic device includes the optoelectronic device as described in claim 8 or 9.

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