Quantum dot and preparation method thereof, thin film and light-emitting device

Abstract

The embodiment of the invention provides a quantum dot, a preparation method thereof, a thin film and a light-emitting device. According to the preparation method of the quantum dots, provided by the embodiment of the invention, the quantum dot crystal nucleuses are screened according to the principle that the sedimentation rates of the quantum dot crystal nucleuses with different particle sizes are different, and the quantum dot crystal nucleuses with relatively uniform particle sizes collected in one or N continuous time periods are selected for shell coating, so that the quantum dots are obtained; and the prepared quantum dot has narrower half-peak width and better luminous purity.

Description

Technical Field

[0001] This application relates to the technical field of quantum dots, and particularly to a quantum dot, a preparation method thereof, a thin film and a light-emitting device. Background Art

[0002] Quantum Dots (QD) are nanomaterials with a particle size in the range of 1 - 20 nanometers and having a crystal structure, and have excellent optical properties, such as a narrow full width at half maximum, strong optical stability, continuously controllable wavelength, and high quantum efficiency. They have been widely used in many fields such as display, lighting, solar energy, and biological labeling. Since the size of quantum dots is within the radius of bulk excitons, excitons always exist on the surface of quantum dots, so the exciton state properties of quantum dots are greatly affected by the surface properties of quantum dots. In order to reduce the influence of surface effects on the performance of quantum dots, materials researchers can effectively reduce the defect state energy levels introduced by lattice defects on the surface of the quantum dot crystal core by regrowing one or more shell materials with continuously widened bandgaps or inert inorganic shells on the surface of the quantum dot crystal core, and avoid the loss of energy in the form of light or heat due to electrons and holes being trapped by the defect energy levels in the excited state quantum dots. The coating of the wide-bandgap shell can improve the optical properties and stability of the quantum dot crystal core.

[0003] However, the full width at half maximum of the emission spectrum of existing core-shell structure quantum dots is relatively large, resulting in poor emission purity of the quantum dots. Summary of the Invention

[0004] Based on this, embodiments of this application provide a quantum dot, a preparation method thereof, a thin film and a light-emitting device.

[0005] In a first aspect, embodiments of this application provide a preparation method of a quantum dot, including:

[0006] Providing a first dispersion solution, the first dispersion solution includes a first solvent and quantum dot crystal cores dispersed in the first solvent, and ligands are connected to the surface of the quantum dot crystal cores;

[0007] Mixing the first dispersion solution with a second solvent to obtain a second dispersion solution, the second solvent is miscible with the first solvent, the ligand is insoluble in the second solvent, and the process of precipitating the quantum dot crystal cores in the second dispersion solution is divided into M time periods, and the outer surfaces of the quantum dot crystal cores collected in one or N consecutive time periods are coated with a shell, both M and N are integers, and M≥2, 1<N<M, to obtain the quantum dot.

[0008] In a second aspect, embodiments of this application provide a quantum dot prepared by using the preparation method of the quantum dot as described above.

[0009] In a third aspect, embodiments of this application provide a thin film including the quantum dot as described above.

[0010] In a fourth aspect, an embodiment of the present application provides a light-emitting device, comprising a cathode and an anode that are arranged opposite to each other, and a functional layer arranged between the cathode and the anode, wherein the functional layer comprises the thin film as described above.

[0011] The method for preparing quantum dots provided in the embodiment of the present application screens quantum dot nuclei according to the principle that quantum dot nuclei with different particle sizes have different sedimentation rates, and selects quantum dot nuclei with relatively uniform particle sizes collected within the second time period for shell coating to obtain quantum dots. The prepared quantum dots have a narrow half-peak width and better luminescence purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments.

[0013] Figure 1 A flow chart of a method for preparing quantum dots provided in an embodiment of the present application.

[0014] Figure 2 A schematic diagram of the structure of a light-emitting device provided in an embodiment of the present application.

[0015] Figure 3 This is the emission spectrum of the quantum dots prepared in Quantum Dot Example 1 provided in the examples of the present application.

[0016] Figure 4 This is the emission spectrum of the quantum dots prepared in the quantum dot comparative example 1 provided in the examples of the present application.

[0017] Component Symbols:

[0018] 100 - light-emitting device; 10 - anode; 20 - hole injection layer; 30 - hole transport layer; 40 - thin film; 50 - electron transport layer; 60 - cathode. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only 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 making creative work are within the scope of protection of this application.

[0020] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0021] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c" can all mean: a, b, c, a+b, a+c, b+c, or a+b+c, where a, b, c can be single or multiple, respectively.

[0022] See also Figure 1 , the present application embodiment provides a method for preparing quantum dots, comprising:

[0023] S100, providing a first dispersed solution, wherein the first dispersed solution includes a first solvent and quantum dot crystal nuclei dispersed in the first solvent, wherein ligands are connected to surfaces of the quantum dot crystal nuclei.

[0024] Exemplarily, the material of the quantum dot crystal core includes at least one of a II-VI group compound, an IV-VI group compound, a III-V group compound and an I-III-VI group compound, and the II-VI group compound is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnS e, at least one of CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSe At least one of S, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, and the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, In At least one of NP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2 and AgInS2.

[0025] Optionally, the material of the quantum dot crystal core includes at least one of InP, InAs, InZnP and InGaP.

[0026] Exemplarily, the ligand includes one or more of aliphatic amine ligands having 1 to 24 carbon atoms, fatty acid ligands having 1 to 24 carbon atoms, aliphatic thiol ligands having 1 to 24 carbon atoms, trialiphatic phosphines having 9 to 30 carbon atoms, triaryl phosphine having 18 to 30 carbon atoms, trialiphatic phosphine oxides having 9 to 30 carbon atoms, triaryl phosphine oxides having 18 to 30 carbon atoms, carboxylate ligands, phosphate ligands and halide ion ligands.

[0027] Illustratively, the fatty amine ligand having 1 to 24 carbon atoms includes one or more of oleylamine, n-decylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, myristicamine, palmitylamine, and stearylamine.

[0028] Illustratively, the fatty acid ligand having 1 to 24 carbon atoms includes one or more of oleic acid, decanoic acid, caprylic acid, dioctanoic acid, trioctanoic acid, dodecanoic acid, myristic acid, palmitic acid, and stearic acid.

[0029] Illustratively, the aliphatic thiol ligand having 1 to 24 carbon atoms includes one or more of hexanethiol, heptathiol, octanethiol, nonanethiol, decanethiol, dodecanethiol, tetradecanethiol, and hexadecanethiol.

[0030] Exemplarily, the carboxylate ligand is selected from one or more of a magnesium carboxylate ligand, a calcium carboxylate ligand, an aluminum carboxylate ligand, a zirconium carboxylate ligand, a lithium carboxylate ligand, a sodium carboxylate ligand and a barium carboxylate ligand; wherein the carboxylate in the carboxylate ligand is a fatty acid radical ion having 1 to 20 carbon atoms.

[0031] Exemplarily, the phosphate ligand is selected from one or more of a magnesium phosphate ligand, a calcium phosphate ligand, an aluminum phosphate ligand, a zirconium phosphate ligand, a lithium phosphate ligand, a sodium phosphate ligand, and a barium phosphate ligand.

[0032] Illustratively, the halogen ion ligand is selected from one or more of fluoride ion, chloride ion, bromide ion, and iodide ion.

[0033] Illustratively, the trialiphatic phosphine having 9 to 30 carbon atoms is selected from one or more of tripropyl phosphine, tributyl phosphine, tripentyl phosphine, trihexyl phosphine, triheptyl phosphine, trioctyl phosphine, trinonyl phosphine and tridecyl phosphine.

[0034] Illustratively, the triaryl phosphine having 18 to 30 carbon atoms is selected from one or more of triphenylphosphine, tri(m-toluene)phosphine, tri(2-tolyl)phosphine, and tri(p-methylphenyl)phosphine.

[0035] Illustratively, the trialiphatic phosphine oxide having 9 to 30 carbon atoms is selected from one or more of tripropyl phosphine oxide, tributyl phosphine oxide, tripentyl phosphine oxide, trihexyl phosphine oxide, triheptyl phosphine oxide, trioctyl phosphine oxide, trinonyl phosphine oxide, and tridecyl phosphine oxide.

[0036] Illustratively, the triaryl phosphine oxide having 18 to 30 carbon atoms is selected from one or more of triphenyl phosphine oxide, tri(m-toluene) phosphine oxide, tri(2-tolyl) phosphine oxide, and tri(p-methylphenyl) phosphine oxide.

[0037] In some embodiments, the material of the quantum dot crystal core includes InP, and providing the quantum dot crystal core with a ligand connected to the surface includes:

[0038] Step 110, mixing an indium source, a coordinating solvent, and a non-coordinating solvent to obtain a first mixture, heating the first mixture to 80° C.-120° C. (e.g., 80° C., 90° C., 100° C., 110° C., 120° C., etc.), and maintaining the mixture at 80° C.-120° C. for 1 hour to 3 hours (e.g., 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.);

[0039] Step 120, cooling the first mixture to 20°C-50°C, mixing the first mixture with a first organic phosphorus source and a first phosphine-containing coordinating solvent to obtain a second mixture, heating the second mixture to 260°C-310°C (e.g., 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, etc.), and maintaining the temperature at 260°C-310°C for 1 minute to 5 minutes (e.g., 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, etc.);

[0040] Step 130, cooling the second mixture to 50° C.-220° C. (e.g., 50° C., 70° C., 100° C., 130° C., 150° C., 180° C., 200° C., 220° C., etc.), mixing the second mixture with an indium precursor to obtain a third mixture, and maintaining the third mixture at 50° C.-220° C. for 20 minutes-40 minutes (e.g., 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.);

[0041] Step 140, cooling the third mixture to 20°C-50°C (for example, 20°C, 30°C, 40°C, 50°C, etc.), mixing the third mixture with a second organic phosphorus source and a second phosphine-containing coordinating solvent to obtain a fourth mixture, heating the fourth mixture to 260°C-310°C (for example, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, etc.), and maintaining it at 260°C-310°C for 1 minute to 5 minutes (for example, 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, etc.) to obtain quantum dot nuclei.

[0042] It should be noted that the above-mentioned method for preparing quantum dot crystal nuclei, by adding an organic phosphorus source, a phosphine-containing coordination solvent, and an indium precursor under low temperature conditions, reacting the components under high temperature conditions, and adding the raw materials in a cycle for multiple times, is conducive to the gradual growth of the quantum dot crystal nuclei, making the morphology and size of the quantum dot crystal nuclei more uniform, thereby making the morphology and size of the quantum dots more uniform, thereby improving the luminous efficiency and service life of the quantum dots. In the traditional method for preparing InP quantum dot crystal nuclei, an indium precursor is usually injected under high temperature conditions, which will lead to problems such as self-nucleation of the indium precursor and uneven growth of the quantum dot crystal nuclei.

[0043] Illustratively, in step 110 , step 120 , step 130 , and step 140 , the components in the first mixture, the second mixture, the third mixture, and the fourth mixture may be mixed by stirring.

[0044] It should be noted that in step 110, the indium source, the coordinating solvent and the non-coordinating solvent are mixed and heated to 80°C-120°C, so that the indium source and the coordinating solvent can react to obtain an indium precursor (such as indium oleate, indium myristic acid), wherein the coordinating solvent is used as a coordinating ligand of the cation and the non-coordinating solvent is used as a diluting solvent.

[0045] Exemplarily, in step 110, the first mixture can be heated to 80-120°C under vacuum (vacuum degree is less than or equal to 150Pa) and maintained for 1 hour to 3 hours, and then an inert gas (such as nitrogen or argon) is bubbled into the first mixture to heat the first mixture to 80°C-120°C. The purpose of vacuuming is to effectively remove low-boiling point organic impurities in the first mixture. Since the subsequent reaction needs to be carried out at normal pressure, the inert gas is bubbled in. In addition, the bubbling of inert gas can also expel water and oxygen in the first mixture to prevent water and oxygen from affecting the subsequent reaction.

[0046] It should be noted that in step 120, cooling the first mixture to 20°C-50°C can avoid adding the organic phosphorus source and the phosphine-containing coordination solvent under high temperature conditions, and can avoid the raw materials from reacting rapidly under high temperature conditions before the organic phosphorus source and the phosphine-containing coordination solvent are evenly stirred, thereby causing uneven growth of quantum dot nuclei in different regions of the reaction system.

[0047] It should be noted that in step 120, the organic phosphorus source is used as the anion source for the formation of quantum dots, the phosphorus-containing coordination solvent is used as a diluent, and the activity of the anion source can be adjusted. After the organic phosphorus source, the phosphorus-containing coordination solvent and indium acid react at high temperature, InP nanocrystals are obtained, and the InP nanocrystals gradually grow into InP luminescent cores.

[0048] It should be noted that in step 130, the reason for cooling the second mixture to 50°C-220°C is that: by cooling, the ripening reaction of the InP luminescent core is terminated, which is convenient for the subsequent replenishment of the indium precursor. At a lower temperature, the replenished indium precursor can be prevented from reacting with the organic phosphorus source in an un-evenly stirred state. It can be understood that by replenishing the indium precursor in step 130, the indium precursor can react with the incompletely reacted organic phosphorus source in the second mixture, so that the InP luminescent core grows further.

[0049] It should be noted that in step 140, the organic phosphorus source and the phosphine-containing coordination solvent are added after the third mixture is cooled to 20°C-50°C, which can avoid the raw materials from reacting rapidly under high temperature conditions before the organic phosphorus source and the phosphine-containing coordination solvent are evenly stirred, thereby preventing the growth of quantum dot nuclei in different regions of the reaction system from being uneven.

[0050] It is understandable that by adding indium precursor in step 130 and adding organic phosphorus source and phosphine-containing coordination solvent in step 140, the InP luminescent core can be gradually grown and the size can be continuously increased, and finally an InP quantum dot crystal core of the expected size can be obtained.

[0051] Exemplarily, the indium source includes at least one of indium acetate and indium halide. Exemplarily, the indium halide includes at least one of indium fluoride, indium chloride, indium bromide, and indium iodide.

[0052] Illustratively, the coordinating solvent includes at least one of palmitic acid, myristic acid, oleic acid, and stearic acid.

[0053] Exemplarily, the non-coordinating solvent includes at least one of n-octadecane (ODE), octadecene, hexadecene, and paraffin oil.

[0054] Illustratively, the first organic phosphorus source and the second organic phosphorus source each include at least one of [P(NMe2)3(tris(dimethylamino)phosphine) and P(TMS)3(tris(trimethylsilyl)phosphine).

[0055] Illustratively, the first phosphine-containing coordinating solvent and the second phosphine-containing coordinating solvent each include at least one of TOP (tri-n-octylphosphine), TBP (tributylphosphine), and DPP (diphenylphosphine).

[0056] In some embodiments, the first organophosphorus source and the second organophosphorus source are the same, and the first phosphine-containing coordinating solvent and the second phosphine-containing coordinating solvent are the same.

[0057] Exemplarily, the indium precursor includes at least one of indium palmitate, indium myristic acid, indium oleate, and indium stearate.

[0058] Illustratively, the molar ratio of the indium source to the coordinating solvent is 1:(3-10), such as 1:3, 1:5, 1:7, 1:10, etc.

[0059] Illustratively, the molar ratio of the indium source to the first organic phosphorus source is 1:(0.1-1), for example, 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:1, etc.

[0060] Illustratively, the molar ratio of the indium precursor to the indium source is 1:(1-5), such as 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0061] Illustratively, the molar ratio of the indium source to the second organic phosphorus source is 1:(0.2-0.8), for example, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, etc.

[0062] For example, after obtaining the quantum dot crystal core, the quantum dot crystal core can be mixed with zinc carboxylate to obtain the quantum dot crystal core with zinc carboxylate connected to the surface.

[0063] It should be noted that the reason for adding zinc carboxylate is that there are relatively many dangling bonds (i.e., uncoordinated atoms) on the surface of the synthesized quantum dot luminescent core. By connecting zinc carboxylate to the surface of the quantum dot crystal core, zinc carboxylate can be used to passivate the defect sites on the surface of the quantum dot crystal core, thereby improving the stability of the quantum dot crystal core, and can improve the adhesion between the shell material and the quantum dot crystal core when the shell material is coated on the surface of the quantum dot crystal core.

[0064] Illustratively, the zinc carboxylate may include at least one of zinc stearate, zinc oleate, zinc myristate, zinc palmitate, and zinc myristate.

[0065] For example, the first solvent includes substituted or unsubstituted C5-C18 aliphatic hydrocarbons, substituted or unsubstituted C6-C10 aromatic hydrocarbons, R1-O-R2 and At least one of the following, wherein R1 and R2 are each independently selected from substituted or unsubstituted C2-C10 aliphatic hydrocarbon groups, n is 0 or 1, and m is 0 or an integer greater than 0; when substituted by a substituent, each occurrence of the substituent is each independently selected from one or more of halogen, C1-C6 alkyl, and C1-C6 alkoxy.

[0066] Illustratively, the second solvent includes at least one of R3-OH and R4-COO-R5, wherein R3, R4 and R5 are each independently selected from substituted or unsubstituted C1-C10 aliphatic hydrocarbon groups.

[0067] Exemplarily, the first solvent includes at least one of dichloromethane, chloroform, toluene, n-hexane, cyclohexane, n-heptane, n-octane, cycloheptane, tetrahydrofuran, tetrahydropyran, dioxane, propylene oxide, butylene oxide, and dioxane.

[0068] Exemplarily, the second solvent includes at least one of methanol, ethanol, isopropanol, n-butanol, n-pentanol, and ethyl acetate.

[0069] S200: Mix the first dispersion solution with the second solvent to obtain a second dispersion solution. The second solvent is miscible with the first solvent, and the ligand is insoluble in the second solvent. The process of precipitating the quantum dot nuclei in the second dispersion solution is divided into M time periods, and the outer surface of the quantum dot nuclei collected in one or N consecutive time periods is coated with a shell layer. Both M and N are integers, and M≥2, 1<N<M, to obtain the quantum dots.

[0070] Exemplarily, M can be 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., and N can be 2, 3, 4, 5, 6, 7, 8, etc.

[0071] Exemplarily, the process of dividing the process of precipitating the quantum dot nuclei in the second dispersion solution into M time periods and coating the outer surface of the quantum dot nuclei collected in one or N consecutive time periods includes: sequentially dividing the process of sedimenting the quantum dot nuclei in the second dispersion solution into a first time period, a second time period, and a third time period, and coating the outer surface of the quantum dot nuclei collected in the second time period.

[0072] Exemplarily, when M≥4, it is possible to select to coat the outer surface of the quantum dot nuclei collected in one or N consecutive time periods in the middle of the M time periods. At this time, there is at least one time period before the N consecutive time periods, and at least one time period after the N consecutive time periods.

[0073] Exemplarily, the solubility of the ligand in the second solvent is less than or equal to 0.1 mg / ml, such as 0.1 mg / ml, 0.08 mg / ml, 0.05 mg / ml, 0.03 mg / ml, 0.01 mg / ml, etc.

[0074] Exemplarily, the solubility of the second solvent in the first solvent is greater than or equal to 1 mg / ml, such as 1 mg / ml, 10 mg / ml, 100 mg / ml, 1000 mg / ml, 10000 mg / ml, etc. In some embodiments, the second solvent can be miscible with the first solvent in any ratio.

[0075] Exemplarily, the second solvent includes at least one of methanol, ethanol, isopropanol, n-butanol, n-pentanol, and ethyl acetate.

[0076] Illustratively, the volume ratio of the first solvent to the second solvent can be (4-6):(3-10), for example, 4:3, 4:5, 4:7, 4:10, 5:3, 1:1, 5:7, 5:10, 6:3, 6:5, 6:7, 6:10, etc.

[0077] Exemplarily, the quantum dot crystal nuclei collected in the first time period account for 15wt%-20wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution, the quantum dot crystal nuclei collected in the second time period account for 60wt%-70wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution, and the quantum dot crystal nuclei collected in the third time period account for 15wt%-20wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution.

[0078] It should be noted that the principle of collecting the quantum dot nuclei precipitated in the second dispersed solution in the first time period, the second time period and the third time period is as follows:

[0079] In S100, in the first dispersed solution prepared, the quantum dot nuclei can be stably dispersed in the first solvent without agglomeration and sedimentation. This is because the mutual repulsion between the organic ligands coated on the surface of the quantum dot nuclei is equivalent to the van der Waals force, and the ligands and the first solvent are equivalent to setting a barrier between adjacent quantum dot nuclei to prevent the quantum dot nuclei from agglomeration and sedimentation.

[0080] In S200, when the first dispersed solution is introduced into the second solvent to obtain the second dispersed solution, since the ligands on the surface of the quantum dot nuclei are insoluble in the second solvent, the solubility of the ligands in the second dispersed solution decreases, the mutual repulsion between the ligands is weakened, and the van der Waals forces between them are unbalanced. Since the larger quantum dot nuclei have a smaller specific surface area, that is, the surface energy is smaller, the barrier effect provided by the ligands and the second solvent to the large-sized quantum dot nuclei is most significantly weakened, so that the quantum dot nuclei with larger particles gather and settle first, and the quantum dot nuclei with smaller particles gather and settle later. That is to say, the particle size of the quantum dot nuclei collected in the first time period, the quantum dot nuclei collected in the second time period, and the quantum dot nuclei collected in the third time period gradually decreases.

[0081] Illustratively, in the first time period, the second time period, and the third time period, the quantum dot nuclei precipitated in the second dispersed solution can be separated from the solution by centrifugation.

[0082] Illustratively, the proportion of quantum dot nuclei collected in the first time period in the total mass of quantum dot nuclei in the second dispersed solution may be 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, etc.

[0083] Exemplarily, the proportion of quantum dot crystal nuclei collected in the second time period in the total mass of quantum dot crystal nuclei in the second dispersed solution can be 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, 70wt%, etc.

[0084] Exemplarily, the proportion of quantum dot crystal nuclei collected in the third time period in the total mass of the quantum dot crystal nuclei in the second dispersed solution may be 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, etc.

[0085] Exemplarily, the material of the shell layer includes at least one of a II-VI compound, a IV-VI compound, a III-V compound, and a I-III-VI compound, and the II-VI compound is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, At least one of CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound is selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS , PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, and the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InN At least one of P, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound is selected from at least one of CuInS2, CuInSe2 and AgInS2.

[0086] Optionally, the material of the shell layer includes at least one of ZnSe, ZnSeS, ZnS, InZnP and InGaP.

[0087] In summary, the method for preparing quantum dots provided in the embodiments of the present application screens quantum dot nuclei according to the principle that quantum dot nuclei with different particle sizes have different sedimentation rates, and selects quantum dot nuclei with relatively uniform particle sizes collected within the second time period for shell coating to obtain quantum dots. The prepared quantum dots have a narrow half-peak width and better luminescence purity.

[0088] The embodiment of the present application also provides a quantum dot, which is prepared by the method for preparing the quantum dot in any of the above embodiments.

[0089] Exemplarily, the material of the quantum dot core and the material of the shell layer each include at least one of a II-VI group compound, a IV-VI group compound, a III-V group compound and a I-III-VI group compound.

[0090] Optionally, the material of the quantum dot crystal core includes at least one of InP, InAs, InZnP and InGaP.

[0091] Optionally, the material of the shell layer includes at least one of ZnSe, ZnSeS, ZnS, InZnP and InGaP.

[0092] An embodiment of the present application also provides a thin film, comprising the quantum dots in any of the above embodiments.

[0093] Illustratively, the film includes, by weight, 10-40 parts of quantum dots, 40-90 parts of polymers, and 0-30 parts of light diffusion particles.

[0094] Exemplarily, the particle size of the light diffusion particles is 100 nm to 250 nm, for example, 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 230 nm, 250 nm, etc.

[0095] It should be noted that when the film further includes a polymer and light diffusion particles, the film can be used as a quantum dot color conversion film (QDCC) or a quantum dot enhancement film (QDEF) in a display device to achieve full-color display.

[0096] Exemplarily, in the film, the number of quantum dots can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, etc., the number of polymers can be 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, etc., and the number of light diffusion particles can be 0 parts, 1 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc.

[0097] Exemplarily, the polymer includes at least one of polystyrene (PS), polyvinyl alcohol (PVA), polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI), epoxidized 1,4-polybutadiene (EPB), glycidyl methacrylate-ethyl acrylate copolymer (PGMA-CO-EA), divinyl phthalate (PDDP), polybutene-1 sulfone (PBS), polyglycidyl methacrylate, polyimide paint, epoxidized 1,4-polybutadiene (EPB), cycloolefin polymer (COP), chloride-modified polymethyl methacrylate, polystyrene sulfone, polyethylene, polypropylene, polyacrylic acid, polymethyl acrylate, polyacrylamide, polyvinyl alkyl ether, polyvinyl methyl ether, polyisobutylene, poly-α-methylstyrene, polymethyl methacrylate, polymethacrylamide, and polymethylisopropenyl ketone.

[0098] Exemplarily, the light diffusing particles include at least one of inorganic particles and organic particles, the material of the inorganic particles includes at least one of BaSO4, CaCO3, Al2O3, TiO2 and SiO2, and the organic particles include at least one of polystyrene microspheres (PS), polymethyl methacrylate (PMMA) and silicone microspheres.

[0099] Exemplarily, the film may further include 1-10 parts by weight of a photoinitiator, which is used to initiate the polymerization and curing of the polymer. At this time, the material of the film is a photoresist material, and in some embodiments, the photoinitiator includes at least one of a diimidazole compound, a benzoin compound, a polynuclear quinone compound, a benzophenone compound, an acetophenone compound, a triazine compound, a diazo compound, an anthrone compound, a xanthonone compound, an oxime ester compound, an iodonium salt, and a sulfonium salt.

[0100] See also Figure 2 The embodiment of the present application further provides a light-emitting device 100, comprising a cathode 60 and an anode 10 arranged opposite to each other, and a functional layer arranged between the cathode 60 and the anode 10, wherein the functional layer comprises the film 40 in any of the above embodiments.

[0101] See also Figure 2 The functional layer includes a light-emitting layer, and the light-emitting layer is the film 40 in any of the above embodiments.

[0102] Exemplarily, the functional layer further includes a hole functional layer, the hole functional layer is located between the anode 10 and the film 40, the hole functional layer includes a hole transport layer 30 and / or a hole injection layer 20, wherein when the hole transport layer 30 and the hole injection layer 20 exist at the same time, the hole injection layer 20 is closer to the anode 10 relative to the hole transport layer 30, and the material of the hole transport layer 30 includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1, 1'-biphenyl-4,4"-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly(N,N'bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tri(N-carbazolyl)-triphenylamine, 4,4',4'-tri(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-( 4-sec-butylphenyl)diphenylamine)), poly(N-vinylcarbazole) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-di(4-methyl) At least one of [(phenyl)aniline], 1,3-di(carbazole-9-yl)benzene, polyaniline, polypyrrole, poly(p-phenylene vinylene), aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, polyspirofluorene and its derivatives, polythiophene and its derivatives, and poly(9,9-n-dioctyl-2,7-fluorene-alt-9-isooctyl-3,6-carbazole).

[0103] Exemplarily, the material of the hole injection layer 20 includes at least one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and its derivatives, copper phthalocyanine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, polydioxyethylthiophene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, transition metal oxides and transition metal sulfur compounds.

[0104] Exemplarily, the functional layer also includes an electron transport layer 50, which is located between the cathode 60 and the thin film 40. The material of the electron transport layer 50 includes at least one of metal oxides, doped metal oxides, II-VI semiconductor materials, III-V semiconductor materials and I-III-VI semiconductor materials. The metal oxide is selected from at least one of ZnO, BaO, TiO2, and SnO2; the metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2, and SnO2, the doping element is selected from at least one of Al, Mg, Li, In, and Ga, the II-VI semiconductor material is selected from at least one of ZnS, ZnSe, and CdS; the III-V semiconductor material is selected from at least one of InP and GaP; the I-III-VI semiconductor material is selected from at least one of CuInS and CuGaS.

[0105] Exemplarily, the cathode 60 and the anode 10 are independently selected from a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal element electrode or an alloy electrode, the material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide, the composite electrode includes AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS or ZnS / Al / ZnS, and the material of the metal element electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg and Ba.

[0106] Exemplarily, the thickness of the anode 10 is 60 nm-120 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, etc.

[0107] Exemplarily, the hole injection layer 20 has a thickness of 10 nm-50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0108] Exemplarily, the thickness of the hole transport layer 30 is 10 nm-50 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0109] Exemplarily, the thickness of the thin film 40 is 10 nm-100 nm, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0110] Exemplarily, the thickness of the electron transport layer 50 is 20 nm-100 nm, for example, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.

[0111] Exemplarily, the thickness of the cathode 60 is 60 nm-120 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, etc.

[0112] The quantum dots and their preparation methods, thin films and light-emitting devices provided in the present application are introduced in detail below.

[0113] Quantum dot example 1

[0114] This embodiment provides a quantum dot, and the preparation method thereof includes:

[0115] Step 1, preparation of InP quantum dot nuclei: 0.15mmol indium source (indium acetate), 0.45mmol coordinating solvent (palmitic acid) and 10mL non-coordinating solvent (ODE) were mixed in a 50mL three-necked bottle, and the mixture was heated to 120℃ for 2 hours under vacuum, then nitrogen was bubbled in and cooled to 50℃; subsequently, 0.1mmol organic phosphorus source (P(TMS)3) was mixed with 1mL phosphine-containing coordinating solvent (TOP) and quickly injected into the bottle. After injection, the temperature was raised to 290°C and maintained for 3 minutes; then the mixture was cooled to 200°C, and 1.5 mL of indium precursor solution was slowly injected, the concentration of the indium precursor solution was 0.1 mmol / ml, the indium precursor solution included an indium precursor (indium palmitate) and a solvent (octadecene), nitrogen was bubbled in, and maintained for 30 minutes; then the mixture was cooled to 50°C, 0.1 mmol of an organic phosphorus source (P(TMS)3) was mixed with 1 mL of a phosphine-containing coordination solvent (TOP), and injected into the flask at this temperature; after injection, the temperature was raised and maintained at 290°C for 3 minutes to obtain quantum dot nuclei; after the synthesis of the quantum dot nuclei, 0.24 mmol of zinc stearate (zinc stearate was dissolved in 1 mL of ODE) was injected into the flask, and maintained at 290°C for 10 minutes, cooled, and purified.

[0116] Step 2: Disperse the quantum dot crystal cores obtained in step 1 in a first solvent (n-hexane) to prepare a first dispersed solution with a quantum dot crystal core mass concentration of 100 mg / ml.

[0117] Step 3: Take 5 ml of the first dispersed solution (containing 500 mg of quantum dot nuclei), and slowly add 5 ml of the second solvent (ethanol) under continuous stirring to obtain a second dispersed solution. When the second dispersed solution becomes flocculent, continue stirring to completely precipitate the large-particle quantum dot nuclei, and then separate them by centrifugation. Continue to add the second solvent to the supernatant, repeat this process several times, and collect 80 mg of large-particle quantum dot nuclei (16 wt%), wherein the particle size of the large-particle quantum dot nuclei is 7±0.6 nm.

[0118] Step 4: Repeat the same operation in step 3 on the second dispersed solution from which 80 mg of large-particle quantum dot nuclei have been removed, and collect 320 mg of medium-particle quantum dot nuclei (64 wt%), wherein the particle size of the medium-particle quantum dot nuclei is 6.5±0.3 nm.

[0119] Step 5. Repeat the same operation in step 3 on the second dispersed solution from which 80 mg of large-particle quantum dot nuclei and 300 mg of medium-particle quantum dot nuclei have been removed, and 80 mg of small-particle quantum dot nuclei (16 wt%) are collected. The reduced 20 mg of quantum dot nuclei are lost during the operation from step 3 to step 5, and the particle size of the small-particle quantum dot nuclei is 5.8±0.5 nm.

[0120] Step 6, coating the surface of 300 mg of medium-particle quantum dot crystal core with a shell layer (ZnSe / ZnS) to obtain quantum dots (InP / ZnSe / ZnS); wherein the detailed steps of coating the shell layer (ZnSe / ZnS) include: preparing 5 mmol of zinc acetate, 5 ml of oleic acid and 15 ml of octadecene as precursors, adding them to a 100 ml three-necked flask, evacuating, heating to 100°C, introducing argon, and waiting for the water and oxygen treatment to be complete, cooling to 50°C, adding a n-hexane solution containing quantum dot crystal cores, and evacuating to remove the n-hexane solvent, introducing argon, heating to 280°C, adding 0.8 mmol of selenium in n-octylphosphine solution to the quantum dot core system, growing a ZnSe shell on the surface of the quantum dot core crystal core, and then adding 1 mmol of sulfur in n-octylphosphine solution to grow a ZnS shell on the outer layer of InP / ZnSe. The quantum dots were precipitated and purified three times using n-heptane as solvent and ethanol as non-solvent to obtain InP / ZnSe / ZnS quantum dots.

[0121] Quantum Dot Example 2

[0122] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0123] The second solvent added in step 3 is isopropanol.

[0124] Quantum Dot Example 3

[0125] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0126] The second solvent added in step 3 is ethyl acetate.

[0127] Quantum Dot Example 4

[0128] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0129] In step 3, 75 mg of large-particle quantum dot nuclei (15 wt%) were collected;

[0130] In step 4, 340 mg of medium-sized quantum dot nuclei (68 wt%) were collected;

[0131] In step 5, 75 mg of small-particle quantum dot crystal cores (15 wt%) were collected, and the reduced 10 mg of quantum dot crystal cores were lost during the operation of steps 3 to 5.

[0132] Quantum Dot Example 5

[0133] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0134] In step 3, 95 mg of large-particle quantum dot nuclei (19 wt%) were collected;

[0135] In step 4, 305 mg of medium-sized quantum dot nuclei (61 wt%) were collected;

[0136] In step 5, 95 mg of small-particle quantum dot crystal cores (19 wt%) were collected, and the reduced 5 mg of quantum dot crystal cores were lost during the operation of steps 3 to 5.

[0137] Quantum Dot Example 6

[0138] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0139] In step 1, the added indium source is indium chloride, the added coordination solvent is myristic acid, the added organic phosphorus source is [P(NMe2)3, and the added phosphine-containing coordination solvent is TBP. The dosage ratio, addition order and reaction conditions of each component are the same as those in quantum dot embodiment 1.

[0140] Quantum Dot Example 7

[0141] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0142] In step 1, the added indium source is indium bromide, the added coordination solvent is oleic acid, the added phosphine-containing coordination solvent is DPP, and the dosage ratio, addition order and reaction conditions of each component are the same as those in quantum dot embodiment 1.

[0143] Quantum Dot Example 8

[0144] This embodiment provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0145] In step 3, 65 mg of large-particle quantum dot nuclei (13 wt%) were collected;

[0146] In step 4, 360 mg of medium-sized quantum dot nuclei (72 wt%) were collected;

[0147] In step 5, 70 mg of small-particle quantum dot crystal cores (14 wt%) were collected, and the reduced 5 mg of quantum dot crystal cores were lost during the operation of steps 3 to 5.

[0148] Quantum dot comparative example 1

[0149] This comparative example 1 provides a quantum dot, and the preparation method thereof comprises:

[0150] Step 11, preparation of indium phosphide-based quantum dot nuclei: indium acetate (0.15 mmol), palmitic acid (0.45 mmol) and 10 mL of ODE were mixed in a 50 mL three-necked bottle, and the mixture was heated to 120 ° C for 2 hours under vacuum, then filled with N2 and cooled to 50 ° C; then, 0.1 mmol of P (TMS) 3 was mixed with 1 mL of TOP and quickly injected into the bottle. After injection, the temperature was raised to 290°C and maintained for 3 minutes; the mixture was then cooled to 200°C, 1.5 mL of indium precursor solution was slowly injected and kept for 30 minutes; the mixture was then cooled to 50°C, 0.1 mmol P(TMS)3 was mixed with 1 mL TOP and injected into the flask at this temperature; after injection, the temperature was raised and maintained at 290°C for 3 minutes to obtain quantum dot nuclei; after the quantum dot nuclei were synthesized, zinc stearate was injected into the flask at an amount of 0.24 mmol zinc stearate per 1 mL ODE, and the temperature was maintained at 290°C for 10 minutes, cooled, and purified.

[0151] Step 12: growing a shell layer (ZnSe / ZnS) on the surface of the quantum dot nucleus prepared in step 1 to obtain quantum dots (InP / ZnSe / ZnS).

[0152] It can be seen that the difference between quantum dot comparative example 1 and quantum dot example 1 is that the quantum dot nuclei prepared in step 11 are not screened according to size, and a shell layer is directly grown on the surface of all quantum dot nuclei to prepare quantum dots.

[0153] Quantum dot comparison example 2

[0154] This comparative example 2 provides a quantum dot, and the preparation method thereof is different from that of the quantum dot embodiment 1 in that:

[0155] In step 1, InP quantum dot nuclei are prepared by high temperature hot injection method, and the specific steps include: preparing InP quantum dot nuclei: 0.15mmol indium source (indium acetate), 0.45mmol coordination solvent (palmitic acid) and 10mL non-coordinating solvent (ODE) are mixed in 50mL three-necked flasks respectively, and the mixture is heated to 120℃ for 2 hours under vacuum, and then filled with N2 and heated to 290℃; then, 0.1mmol organic phosphorus source (P(TMS)3) and 1mL phosphine-containing coordination solvent (TOP) are mixed; The method comprises the following steps: quickly injecting the mixture into a flask; after injection, maintaining the temperature at 290° C. for 3 minutes; then slowly injecting 1.5 mL of an indium precursor solution having a concentration of 0.1 mmol / ml, the indium precursor solution including an indium precursor (indium palmitate) and a solvent (octadecene) for 30 minutes; then mixing 0.1 mmol of an organic phosphorus source (P(TMS)3) with 1 mL of a phosphine-containing coordination solvent (TOP), and injecting the mixture into the flask at the same temperature; after injection, incubating at 290° C. for 3 minutes to obtain a quantum dot crystal nucleus; cooling the mixture and purifying the mixture.

[0156] Film Example 1

[0157] This embodiment provides a thin film, and the preparation method thereof includes:

[0158] Step 21, providing 30 mg / ml of a quantum dot dispersion solution, wherein the quantum dot dispersion solution comprises quantum dots and n-octane, wherein the quantum dots are the quantum dots prepared in Quantum Dot Example 1;

[0159] Step 22: Spin-coat the quantum dot dispersion solution at 1500 rpm and anneal at 80° C. for 10 min to form a 40 nm thin film.

[0160] Film Example 2

[0161] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0162] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 2.

[0163] Film Example 3

[0164] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 3 in that:

[0165] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 3.

[0166] Film Example 4

[0167] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0168] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 4.

[0169] Film Example 5

[0170] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0171] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 5.

[0172] Film Example 6

[0173] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 3 in that:

[0174] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 6.

[0175] Film Example 7

[0176] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0177] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 7.

[0178] Film Example 8

[0179] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0180] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot embodiment 8.

[0181] Film Example 9

[0182] This embodiment provides a thin film, and the preparation method thereof includes:

[0183] Step 210, providing quantum dot ink, wherein the quantum dot ink comprises 15wt% of quantum dot material, 52wt% of polymethyl methacrylate (polymer), 5wt% of benzophenone (initiator), 10% of TiO2 (light diffusion particles), and 25wt% of propylene glycol methyl ether acetate (organic solvent); wherein the quantum dot material is the quantum dot prepared in Quantum Dot Example 1;

[0184] Step 220, spin coating the quantum dot polymer solution on the optical glass substrate at a speed of 1000 rpm for 60 seconds to obtain a wet film; pre-drying the wet film under a vacuum of 104 MPa for 5 minutes to remove part of the propylene glycol methyl ether acetate solvent; using a 365 nm ultraviolet lamp at 50 mJ / cm 2 The film was cured by irradiation at a dose of , and then heated at 200°C for 10 min to obtain a quantum dot film with a thickness of 5 μm.

[0185] Film Example 10

[0186] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0187] In step 210, the quantum dot material in the quantum dot ink is the quantum dots prepared in quantum dot embodiment 2.

[0188] Film Example 11

[0189] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 3 in that:

[0190] In step 210, the quantum dot material in the quantum dot ink is the quantum dots prepared in quantum dot embodiment 3.

[0191] Film Example 12

[0192] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0193] In step 210, the quantum dot material in the quantum dot ink is the quantum dots prepared in quantum dot embodiment 4.

[0194] Film Example 13

[0195] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0196] In step 210, the quantum dot material in the quantum dot ink is the quantum dots prepared in quantum dot embodiment 5.

[0197] Film Example 14

[0198] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 3 in that:

[0199] In step 210, the quantum dot material in the quantum dot ink is the quantum dots prepared in quantum dot embodiment 6.

[0200] Film Example 15

[0201] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0202] In step 210, the quantum dot material in the quantum dot ink is the quantum dots prepared in quantum dot embodiment 7.

[0203] Film Comparative Example 1

[0204] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0205] In step 21, the quantum dots in the quantum dot dispersion solution are the quantum dots prepared in quantum dot comparative example 1.

[0206] Film Comparative Example 2

[0207] This embodiment provides a film, and the preparation method thereof is different from that of the film embodiment 1 in that:

[0208] In step 21, the quantum dots in the quantum dot dispersed solution are the quantum dots prepared in quantum dot comparative example 2.

[0209] Device Example 1

[0210] This embodiment provides a light emitting device, and the preparation method thereof includes:

[0211] Step 31, spin-coating PEDOT:PSS material on the 100nm ITO anode, annealing at 100°C for 15min, to obtain a 30nm hole injection layer;

[0212] Step 32, spin-coating PF8Cz material on the hole injection layer, annealing at 100° C. for 15 min, to obtain a 30 nm hole transport layer;

[0213] Step 33, forming a thin film on the hole transport layer according to the method of thin film embodiment 1;

[0214] Step 34, spin-coating a butanol solution of ZnMgO on the film, annealing at 80° C. for 10 min, to obtain a 40 nm electron transport layer;

[0215] Step 35: evaporate Ag on the electron transport layer to obtain a cathode with a thickness of 100 nm, and encapsulate to form a light-emitting device.

[0216] Device Example 2

[0217] This embodiment provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 2.

[0218] Device Example 3

[0219] This embodiment provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 3.

[0220] Device Example 4

[0221] This embodiment provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 4.

[0222] Device Example 5

[0223] This embodiment provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 5.

[0224] Device Example 6

[0225] This embodiment provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 6.

[0226] Device Example 7

[0227] This embodiment provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 7.

[0228] Device Example 8

[0229] This comparative example provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that: in step 33, a thin film is formed on the hole transport layer according to the method of thin film embodiment 8.

[0230] Device Comparison Example 1

[0231] This comparative example provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that:

[0232] In step 33, a thin film is formed on the hole transport layer according to the method of thin film comparative example 1.

[0233] Device Comparison Example 2

[0234] This comparative example provides a light-emitting device, and the preparation method thereof is different from that of device embodiment 1 in that:

[0235] In step 33, a thin film is formed on the hole transport layer according to the method of thin film comparative example 2.

[0236] Quantum dot performance test:

[0237] The emission spectra of the quantum dots prepared in quantum dot examples 1-8 and quantum dot comparative examples 1-2 were measured using a fluorescence spectrometer, wherein: Figure 3 The emission spectrum of the quantum dots prepared in quantum dot embodiment 1, Figure 4 The emission spectrum of the quantum dots prepared in quantum dot comparative example 1, the half maximum width (FWHM) of the emission spectra of quantum dot embodiments 1-7 and quantum dot comparative examples 1-2 are shown in Table 1.

[0238] from Figure 3 It can be seen that the full width at half maximum (FWHM) of the emission spectrum of the quantum dots prepared in quantum dot Example 1 is 37 nm.

[0239] from Figure 4 It can be seen that the half maximum width (FWHM) of the emission spectrum of the quantum dots prepared in quantum dot comparative example 1 is 46 nm.

[0240] Table 1

[0241]

[0242] It can be seen from Table 1 that the half-width of the quantum dots prepared by quantum dot embodiments 1-7 of the present application is much smaller than the half-width of the quantum dots prepared by quantum dot comparison example 1. The difference between quantum dot embodiments 1-7 and quantum dot comparison example 1 is that: in the process of preparing quantum dots, quantum dot embodiments 1-7 screen the size of the quantum dot crystal nucleus, and select the medium-grained quantum dot crystal nuclei with relatively uniform size in the middle section for shell coating to obtain quantum dots, while in the process of preparing quantum dots in quantum dot comparison example 1, the size of the quantum dot crystal nucleus is not screened, and all the quantum dot crystal nuclei are directly shell coated to obtain quantum dots. This shows that the present application can improve the uniformity of the size of the prepared quantum dots by screening the size of the quantum dot crystal nucleus during the preparation of quantum dots, thereby reducing the half-width of the emission spectrum of the quantum dots, thereby improving the luminescence purity of the quantum dots.

[0243] It can also be seen from Table 1 that the half-width of the quantum dots prepared by quantum dot embodiments 1-7 of the present application is much smaller than the half-width of the quantum dots prepared by quantum dot comparative example 2. The difference between quantum dot embodiments 1-7 and quantum dot comparative example 2 is that: in the process of preparing quantum dot crystal nuclei, quantum dot embodiments 1-7 adopt the method of adding an organic phosphorus source, a phosphine-containing coordination solvent, and an indium precursor under low temperature conditions, reacting the components under high temperature conditions, and adding raw materials in a cycle for multiple times, which is conducive to the gradual growth of the quantum dot crystal nuclei, making the morphology and size of the quantum dot crystal nuclei more uniform, and thus making the morphology and size of the quantum dots more uniform, thereby reducing the half-width of the emission spectrum of the quantum dots; while quantum dot comparative example 2 adopts a high-temperature injection method in the process of preparing quantum dot crystal nuclei, and the morphology and size uniformity of the prepared quantum dot crystal nuclei are poor, thereby making the morphology and size uniformity of the quantum dots poor, resulting in a larger half-width of the emission spectrum of the quantum dots.

[0244] It can also be seen from Table 1 that the half-peak width of the quantum dots prepared in quantum dot embodiments 1-7 of the present application is much smaller than the half-peak width of the quantum dots prepared in quantum dot embodiment 8. The difference between the known quantum dot embodiments 1-7 and the quantum dot embodiment 8 is that: in quantum dot embodiments 1-7, the quantum dot nuclei collected in the first time period, the second time period, and the third time period respectively account for 15wt%-20wt%, 60wt%-70wt%, and 15wt%-20wt% of the total mass of the quantum dot nuclei in the second dispersed solution; while in quantum dot embodiment 8, the quantum dot nuclei collected in the first time period, the second time period, and the third time period respectively account for 13wt%, 72wt%, and 14wt% of the total mass of the quantum dot nuclei in the second dispersed solution; this shows that when the quantum dot nuclei collected in the first time period and the third time period are in the second dispersed solution, the total mass of the quantum dot nuclei collected in the second time period is less than that in the third time period. When the proportion of the total mass of the quantum dot nuclei in the dispersed solution is less than 15wt%, and the proportion of the quantum dot nuclei collected in the second time period in the total mass of the quantum dot nuclei in the second dispersed solution is greater than 70wt%, the morphology and size uniformity of the prepared quantum dot nuclei are poor, which in turn makes the morphology and size uniformity of the quantum dots poor, resulting in a larger half-peak width of the emission spectrum of the quantum dots; the present application limits the proportion of the quantum dot nuclei collected in the first time period, the second time period, and the third time period in the total mass of the quantum dot nuclei in the second dispersed solution to 15wt%-20wt%, 60wt%-70wt%, and 15wt%-20wt%, respectively, so that the morphology and size of the prepared quantum dot nuclei are relatively uniform, which in turn makes the morphology and size of the quantum dots relatively uniform, thereby effectively reducing the half-peak width of the emission spectrum of the quantum dots.

[0245] Film performance test:

[0246] The performance tests were performed on the films prepared in the film examples 1-8 and the film comparison examples 1-2, and the test methods were as follows:

[0247] The glass substrate was used as a blank control, and the Edinburgh spectrometer was used to test the films prepared in film examples 1-6 and film comparison examples 1-3 and the blank control. After the test was completed, the test spectrum data was integrated and calculated, the integration interval was selected, and the blank control was subtracted from the QDs test result. The result was the final measured fluorescence quantum yield (PLQY) of the QDs.

[0248] The film performance test results are shown in Table 2.

[0249] Table 2

[0250]

[0251]

[0252] It can be seen from Table 2 that the fluorescence quantum yields of the films prepared by film embodiments 1-7 are all greater than the fluorescence quantum yields of the films prepared by film comparison example 1. It is known that the difference between film embodiments 1-7 and film comparison example 1 is that the quantum dots used in film embodiments 1-7 are screened for the size of the quantum dot crystal nuclei during the preparation process, while the quantum dots used in comparison example 1 are not screened for the size of the quantum dot crystal nuclei during the preparation process. This indicates that the particle size of the quantum dots prepared in the embodiments of the present application is more uniform and the shell coating is more uniform, thereby improving the luminescence efficiency of the quantum dots.

[0253] It can also be seen from Table 2 that the fluorescence quantum yields of the films prepared by film embodiments 1-7 are greater than the fluorescence quantum yields of the films prepared by film comparison example 2. It is known that the difference between film embodiments 1-7 and film comparison example 2 is that: the quantum dots used in film embodiments 1-7 adopt the method of adding organic phosphorus source, phosphine-containing coordination solvent, and indium precursor under low temperature conditions in the process of preparing quantum dot crystal nuclei, reacting the components under high temperature conditions, and adding raw materials in a cycle for multiple times, which is conducive to the gradual growth of quantum dot crystal nuclei, making the morphology and size of the quantum dot crystal nuclei more uniform, thereby making the morphology and size of the quantum dots more uniform, thereby improving the luminescence efficiency of the quantum dots; while the quantum dots used in film comparison example 2 adopt the high temperature injection method in the process of preparing quantum dot crystal nuclei, and the morphology and size uniformity of the prepared quantum dot crystal nuclei are poor, thereby making the morphology and size uniformity of the quantum dots poor, resulting in low luminescence efficiency of the quantum dots.

[0254] It can also be seen from Table 2 that the fluorescence quantum yields of the films prepared by film embodiments 1-7 are greater than the fluorescence quantum yields of the films prepared by film embodiment 8. It is known that the difference between film embodiments 1-7 and film embodiment 8 is that: in the process of preparing quantum dot crystal nuclei by the quantum dots used in film embodiments 1-7, the quantum dot crystal nuclei collected in the first time period, the second time period, and the third time period respectively account for 15wt%-20wt%, 60wt%-70wt%, and 15wt%-20wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution; and in the process of preparing quantum dot crystal nuclei by the quantum dots used in film embodiment 8, the quantum dot crystal nuclei collected in the first time period, the second time period, and the third time period respectively account for 13wt%, 72wt%, and 14wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution; This shows that when the first time When the proportion of the quantum dot nuclei collected in the first time period, the second time period, and the third time period in the total mass of the quantum dot nuclei in the second dispersed solution is less than 15wt%, and the proportion of the quantum dot nuclei collected in the second time period in the total mass of the quantum dot nuclei in the second dispersed solution is greater than 70wt%, the morphology and size uniformity of the prepared quantum dot nuclei are poor, which in turn makes the morphology and size uniformity of the quantum dots poor, resulting in low luminescence efficiency of the quantum dots; the present application limits the proportion of the quantum dot nuclei collected in the first time period, the second time period, and the third time period in the total mass of the quantum dot nuclei in the second dispersed solution to 15wt%-20wt%, 60wt%-70wt%, and 15wt%-20wt%, respectively, so that the morphology and size of the prepared quantum dot nuclei are relatively uniform, which in turn makes the morphology and size of the quantum dots relatively uniform, thereby effectively improving the luminescence efficiency of the quantum dots.

[0255] Device performance test:

[0256] The devices prepared in device examples 1-8 and device comparative examples 1-2 were subjected to performance tests, and the test methods were as follows:

[0257] The performance of the optoelectronic devices was tested 1 hour after the packaging was completed. The performance test was carried out in an environment with a temperature of 25° C. and a relative humidity of 40%.

[0258] The photoelectric performance is tested using FPD optical property measurement equipment (including Ocean Optics USB2000, LabView controlled QE-PRO spectrometer, Keithley2400, high-precision digital source meter Keithley6485, optical fiber with an inner diameter of 50μm, device test probes and fixtures, various related connecting wires and data cards, efficiency test cassettes and data acquisition systems to build an efficiency test system) to obtain the start-up voltage, current, brightness, luminescence spectrum and other parameters of each photoelectric device, and then calculate the maximum external quantum efficiency (EQEmax,%), power efficiency and other key parameters.

[0259] The device life detection method includes the following steps: under the drive of a constant current (2mA), using a life test equipment to perform electroluminescence life analysis on each photoelectric device, recording the time required for each photoelectric device to decay from the maximum brightness to 95% (T95,h), and calculating the time required for the brightness of each photoelectric device to decay from 100% to 95% at a brightness of 1000nit through a decay fitting formula (T95@1000nit,h).

[0260] The device performance test results are shown in Table 3.

[0261] Table 3

[0262]

[0263]

[0264] It can be seen from Table 3 that the external quantum efficiency (EQE) and LT95-1knit life of the devices prepared in device embodiments 1-7 are greater than the external quantum efficiency (EQE) and LT95-1knit life of the device prepared in device comparison example 1. It is known that the difference between device embodiments 1-7 and device comparison example 1 is that the quantum dots used in device embodiments 1-7 are screened for the size of the quantum dot crystal nuclei during the preparation process, while the quantum dots used in comparison example 1 are not screened for the size of the quantum dot crystal nuclei during the preparation process. This shows that the particle size of the quantum dots prepared in the embodiments of the present application is more uniform and the shell coating is more uniform, thereby improving the luminescence efficiency and service life of the quantum dots.

[0265] It can also be seen from Table 3 that the external quantum efficiency (EQE) and LT95-1knit life of the devices prepared by device embodiments 1-7 are greater than the external quantum efficiency (EQE) and LT95-1knit life of the devices prepared by device comparative example 2. It is known that the difference between device embodiments 1-7 and device comparative example 1 is that: the quantum dots used in device embodiments 1-7 adopt the method of adding an organic phosphorus source, a phosphine-containing coordination solvent, and an indium precursor under low temperature conditions in the process of preparing quantum dot crystal nuclei, reacting the components under high temperature conditions, and adding raw materials in a cycle for multiple times, which is conducive to the gradual growth of quantum dot crystal nuclei, making the morphology and size of the quantum dot crystal nuclei more uniform, and then making the morphology and size of the quantum dots more uniform, thereby improving the luminescence efficiency and service life of the quantum dots; while the quantum dots used in device comparative example 2 adopt a high-temperature injection method in the process of preparing quantum dot crystal nuclei, and the morphology and size uniformity of the prepared quantum dot crystal nuclei are poor, and then the morphology and size uniformity of the quantum dots are poor, resulting in low luminescence efficiency and service life of the quantum dots.

[0266] It can also be seen from Table 3 that the external quantum efficiency (EQE) and LT95-1knit life of the devices prepared in device embodiments 1-7 are greater than the external quantum efficiency (EQE) and LT95-1knit life of the device prepared in device embodiment 8. The difference between the known device embodiments 1-7 and device embodiment 8 is that: in the process of preparing quantum dot crystal nuclei by the quantum dots used in device embodiments 1-7, the quantum dot crystal nuclei collected in the first time period, the second time period, and the third time period respectively account for 15wt%-20wt%, 60wt%-70wt%, and 15wt%-20wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution; while in the process of preparing quantum dot crystal nuclei by the quantum dots used in device embodiment 8, the quantum dot crystal nuclei collected in the first time period, the second time period, and the third time period respectively account for 13wt%, 72wt%, 14wt% and 13wt% of the total mass of the quantum dot crystal nuclei in the second dispersed solution. wt%; this means that when the proportion of the quantum dot nuclei collected in the first time period and the third time period in the total mass of the quantum dot nuclei in the second dispersed solution is less than 15wt%, and the proportion of the quantum dot nuclei collected in the second time period in the total mass of the quantum dot nuclei in the second dispersed solution is greater than 70wt%, the morphology and size uniformity of the prepared quantum dot nuclei are poor, which in turn makes the morphology and size uniformity of the quantum dots poor, resulting in low luminescence efficiency and service life of the quantum dots; the present application limits the proportion of the quantum dot nuclei collected in the first time period, the second time period, and the third time period in the total mass of the quantum dot nuclei in the second dispersed solution to 15wt%-20wt%, 60wt%-70wt%, and 15wt%-20wt%, respectively, so that the morphology and size of the prepared quantum dot nuclei are relatively uniform, which in turn makes the morphology and size of the quantum dots relatively uniform, thereby effectively improving the luminescence efficiency and service life of the quantum dots.

[0267] The quantum dots and their preparation methods, thin films and light-emitting devices provided in the embodiments of the present application are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A method for preparing quantum dots, characterized in that: Comprising: Providing a first dispersion solution, the first dispersion solution comprising a first solvent and quantum dot crystal nuclei dispersed in the first solvent, with ligands attached to the surface of the quantum dot crystal nuclei; Mixing the first dispersion solution with a second solvent to obtain a second dispersion solution, the second solvent being miscible with the first solvent, the ligand being insoluble in the second solvent, and dividing the process of precipitating the quantum dot crystal nuclei in the second dispersion solution into M time periods, and coating the outer surface of the quantum dot crystal nuclei collected in one or N consecutive time periods, where both M and N are integers, and M≥2, 1<N<M, to obtain the quantum dots.

2. The method for preparing quantum dots according to claim 1, characterized in that: The process of dividing the precipitation of the quantum dot crystal nuclei in the second dispersion solution into M time periods and coating the outer surface of the quantum dot crystal nuclei collected in one or N consecutive time periods includes: sequentially dividing the process of sedimenting the quantum dot crystal nuclei in the second dispersion solution into a first time period, a second time period, and a third time period, and coating the outer surface of the quantum dot crystal nuclei collected in the second time period; and / or, The solubility of the ligand in the second solvent is less than or equal to 0.1 mg / ml; and / or, The solubility of the second solvent in the first solvent is greater than or equal to 1 mg / ml; and / or, The proportion of the quantum dot crystal nuclei collected in the first time period in the total mass of the quantum dot crystal nuclei in the second dispersion solution is 15 wt%-20 wt%, the proportion of the quantum dot crystal nuclei collected in the second time period in the total mass of the quantum dot crystal nuclei in the second dispersion solution is 60 wt%-70 wt%, and the proportion of the quantum dot crystal nuclei collected in the third time period in the total mass of the quantum dot crystal nuclei in the second dispersion solution is 15 wt%-20 wt%; and / or, The first solvent includes substituted or unsubstituted C5-C18 aliphatic hydrocarbons, substituted or unsubstituted C6-C10 aromatic hydrocarbons, R1-O-R2 and At least one of, wherein R1 and R2 are each independently selected from substituted or unsubstituted C2-C10 aliphatic hydrocarbon groups, n is 0 or 1, and m is 0 or an integer greater than 0; when substituted by a substituent, each occurrence of the substituent is independently selected from one or more of halogen, C1-C6 alkyl, and C1-C6 alkoxy; and / or, The second solvent includes at least one of R3-OH and R4-COO-R5, where R3, R4, and R5 are each independently selected from substituted or unsubstituted C1-C10 aliphatic hydrocarbon groups; and / or, The volume ratio of the first solvent to the second solvent is (4-6):(3-10); and / or, The ligand includes one or more of a fatty amine ligand with 1-24 carbon atoms, a fatty acid ligand with 1-24 carbon atoms, a fatty thiol ligand with 1-24 carbon atoms, a trialkylphosphine with 9-30 carbon atoms, a triarylphosphine with 18-30 carbon atoms, a trialkylphosphine oxide with 9-30 carbon atoms, a triaryloxyphosphine with 18-30 carbon atoms, a carboxylate ligand, a phosphate ligand, and a halide ion ligand.

3. The method for preparing quantum dots according to claim 2, characterized in that: The first solvent includes at least one of dichloromethane, chloroform, toluene, n-hexane, cyclohexane, n-heptane, n-octane, cycloheptane, tetrahydrofuran, tetrahydropyran, dioxane, propylene oxide, butylene oxide, and dioxane; and / or, The second solvent includes at least one of methanol, ethanol, isopropanol, n-butanol, n-pentanol, and ethyl acetate; and / or, The fatty amine ligand having 1 to 24 carbon atoms includes one or more of oleylamine, n-decylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, myristicamine, palmitylamine and stearylamine; and / or, The fatty acid ligand having 1 to 24 carbon atoms includes one or more of oleic acid, decanoic acid, octanoic acid, dioctanoic acid, trioctanoic acid, dodecanoic acid, myristic acid, palmitic acid, and stearic acid; and / or, The aliphatic thiol ligand having 1 to 24 carbon atoms includes one or more of hexanethiol, heptathiol, octanethiol, nonanethiol, decanethiol, dodecanethiol, tetradecanethiol, and hexadecanethiol; and / or, The carboxylate ligand is selected from one or more of magnesium carboxylate ligand, calcium carboxylate ligand, aluminum carboxylate ligand, zirconium carboxylate ligand, lithium carboxylate ligand, sodium carboxylate ligand and barium carboxylate ligand; wherein the carboxylate radical in the carboxylate ligand is a fatty acid radical ion having 1 to 20 carbon atoms; and / or, The phosphate ligand is selected from one or more of magnesium phosphate ligand, calcium phosphate ligand, aluminum phosphate ligand, zirconium phosphate ligand, lithium phosphate ligand, sodium phosphate ligand and barium phosphate ligand; and / or, The halogen ion ligand is selected from one or more of fluoride ion, chloride ion, bromide ion and iodide ion; and / or, The trialiphatic phosphine having 9 to 30 carbon atoms is selected from one or more of tripropyl phosphine, tributyl phosphine, tripentyl phosphine, trihexyl phosphine, triheptyl phosphine, trioctyl phosphine, trinonyl phosphine and tridecyl phosphine; and / or, The triarylphosphine having 18 to 30 carbon atoms is selected from one or more of triphenylphosphine, tri(m-toluene)phosphine, tri(2-tolyl)phosphine, tri(p-methylphenyl)phosphine; and / or, The trialiphatic phosphine oxide having 9 to 30 carbon atoms is selected from one or more of tripropyl phosphine oxide, tributyl phosphine oxide, tripentyl phosphine oxide, trihexyl phosphine oxide, triheptyl phosphine oxide, trioctyl phosphine oxide, trinonyl phosphine oxide and tridecyl phosphine oxide; and / or, The triaryl phosphine oxide having 18 to 30 carbon atoms is selected from one or more of triphenyl phosphine oxide, tri(m-toluene) phosphine oxide, tri(2-tolyl) phosphine oxide, and tri(p-methylphenyl) phosphine oxide.

4. The method for preparing quantum dots according to any one of claims 1 to 3, characterized in that: The material of the quantum dot core and the material of the shell each include at least one of a II-VI group compound, an IV-VI group compound, a III-V group compound and an I-III-VI group compound, and the II-VI group compound is selected from CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZ nS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHg SeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, IV-VI compounds are selected from SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnST e, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, and the III-V compound is selected from GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs , AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, the I-III-VI group compound is selected from CuInS2, CuInSe2 and AgInS2; Optionally, the material of the quantum dot crystal core includes at least one of InP, InAs, InZnP and InGaP; Optionally, the material of the shell layer includes at least one of ZnSe, ZnSeS, ZnS, InZnP and InGaP.

5. The method for preparing quantum dots according to claim 4, characterized in that: The material of the quantum dot crystal core includes InP, and the quantum dot crystal core provided with a ligand connected to the surface includes: Mixing an indium source, a coordinating solvent, and a non-coordinating solvent to obtain a first mixture, heating the first mixture to 80° C.-120° C., and maintaining the mixture at 80° C.-120° C. for 1 hour-3 hours; Cooling the first mixture to 20° C.-50° C., mixing the first mixture with a first organic phosphorus source and a first phosphine-containing coordinating solvent to obtain a second mixture, heating the second mixture to 260° C.-310° C., and maintaining the temperature at 260° C.-310° C. for 1 minute to 5 minutes; Cooling the second mixture to 50° C.-220° C., mixing the second mixture with an indium precursor to obtain a third mixture, and maintaining the third mixture at 50° C.-220° C. for 20 minutes-40 minutes; The third mixture is cooled to 20°C-50°C, the third mixture is mixed with a second organic phosphorus source and a second phosphine-containing coordinating solvent to obtain a fourth mixture, the fourth mixture is heated to 260°C-310°C, and maintained at 260°C-310°C for 1 minute to 5 minutes to obtain quantum dot crystal nuclei.

6. The method for preparing quantum dots according to claim 5, characterized in that: The indium source includes indium acetate and indium halide; and / or, The coordinating solvent includes palmitic acid, myristic acid, oleic acid, stearic acid; and / or, The non-coordinating solvent includes n-octadecane, octadecene, hexadecene, paraffin oil; and / or, The first organic phosphorus source and the second organic phosphorus source each include [P(NMe2)3 and P(TMS)3; and / or, The first phosphine-containing coordinating solvent and the second phosphine-containing coordinating solvent each include TOP, TBP, DPP; and / or, The indium precursor includes indium palmitate, indium myristic acid, indium oleate, indium stearate; and / or, The molar ratio of the indium source to the coordinating solvent is 1:(3-10); and / or, The molar ratio of the indium source to the first organic phosphorus source is 1:(0.1-1); and / or, The molar ratio of the indium precursor to the indium source is 1:(1-5); and / or, The molar ratio of the indium source to the second organic phosphorus source is 1:(0.2-0.8); and / or, After the quantum dot crystal core is obtained, the quantum dot crystal core is mixed with zinc carboxylate to obtain the quantum dot crystal core with zinc carboxylate connected to the surface.

7. A quantum dot, characterized in that: The quantum dots are prepared by the method for preparing the quantum dots according to any one of claims 1 to 6.

8. A film, characterized in that: Comprising the quantum dots as described in claim 7.

9. The film according to claim 8, characterized in that In parts by weight, the film comprises 10-40 parts of quantum dots, 40-90 parts of polymers, and 0-30 parts of light diffusion particles; Optionally, the polymer includes at least one of polystyrene, polyvinyl alcohol, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polycarbonate, polyimide, epoxidized 1,4-polybutadiene, glycidyl methacrylate-ethyl acrylate copolymer, ethylene phthalate, polybutene-1 sulfone, polyglycidyl methacrylate, polyimide-based paint, epoxidized 1,4-polybutadiene, cycloolefin polymer, acyl chloride-modified polymethyl methacrylate, polystyrene sulfone, polyethylene, polypropylene, polyacrylic acid, polymethyl acrylate, polyacrylamide, polyvinyl alkyl ether, polyvinyl methyl ether, polyisobutylene, poly-α-methylstyrene, polymethyl methacrylate, polymethacrylamide, and polymethylisopropenyl ketone; Optionally, the light diffusion particles include at least one of inorganic particles and organic particles, the material of the inorganic particles includes at least one of BaSO4, CaCO3, Al2O3, TiO2 and SiO2, and the organic particles include at least one of polystyrene microspheres, polymethyl methacrylate and silicone microspheres.

10. A light emitting device, characterized in that: The invention comprises a cathode and an anode which are arranged opposite to each other, and a functional layer arranged between the cathode and the anode, wherein the functional layer comprises the film according to any one of claims 8 to 9.

11. The light emitting device according to claim 10, characterized in that: The functional layer includes a light-emitting layer, and the light-emitting layer is the thin film according to any one of claims 8 to 9.

12. The light emitting device according to any one of claims 10 to 11, characterized in that: The functional layer further comprises a hole functional layer, the hole functional layer is located between the anode and the film, the hole functional layer comprises a hole transport layer and / or a hole injection layer, wherein when the hole transport layer and the hole injection layer exist at the same time, the hole injection layer is closer to the anode relative to the hole transport layer, and the material of the hole transport layer comprises 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, Poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tri(N-carbazolyl)-triphenylamine, 4,4',4'-tri(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, poly(phenylene vinylene), poly[2-methoxy-5 -(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-phenylene vinylene), aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and its derivatives, at least one of polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, polyspirofluorene and its derivatives, polythiophene and its derivatives, poly(9,9-n-dioctyl-2,7-fluorene-alt-9-isooctyl-3,6-carbazole); the material of the hole injection layer includes at least one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and its derivatives, copper phthalocyanine, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, polydioxyethylthiophene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, transition metal oxides and transition metal sulfur compounds; and / or, The functional layer also includes an electron transport layer, which is located between the cathode and the film. The material of the electron transport layer includes at least one of metal oxides, doped metal oxides, II-VI semiconductor materials, III-V semiconductor materials and I-III-VI semiconductor materials. The metal oxide is selected from at least one of ZnO, BaO, TiO2 and SnO2; the metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2 and SnO2, the doping element is selected from at least one of Al, Mg, Li, In and Ga, the II-VI semiconductor material is selected from at least one of ZnS, ZnSe and CdS; the III-V semiconductor material is selected from at least one of InP and GaP; the I-III-VI semiconductor material is selected from at least one of CuInS and CuGaS; and / or, The cathode and the anode are independently selected from a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal single substance electrode or an alloy electrode. The material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide. The composite electrode includes AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS or ZnS / Al / ZnS. The material of the metal single substance electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg and Ba.

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