Thin film and preparation method thereof, photoelectric device and display device

Abstract

The embodiment of the invention relates to the field of display, in particular to a thin film and a preparation method thereof, a photoelectric device and a display device.The preparation method of the thin film comprises the steps that a saturated solution is provided, and the saturated solution comprises charged nano-particles; and applying an electric field to the saturated solution and performing first energy treatment to obtain the film. The film forming uniformity of the thin film is effectively improved.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and in particular, to a thin film, a preparation method thereof, an optoelectronic device, and a display device. Background Art

[0002] Currently, functional layer thin films can be prepared by electrophoresis. However, the thickness uniformity of the existing functional layer thin films prepared by electrophoresis is poor, and the performance of the thin films needs to be further improved. Summary of the Invention

[0003] Based on this, embodiments of the present application provide a thin film, a preparation method thereof, an optoelectronic device, and a display device.

[0004] To solve the above technical problems, embodiments of the present application provide a preparation method of a thin film, which adopts the following technical solutions:

[0005] A preparation method of a thin film includes:

[0006] providing a saturated solution, where the saturated solution includes charged nanoparticles;

[0007] performing electric field treatment and first energy treatment on the saturated solution to obtain a thin film.

[0008] To solve the above technical problems, embodiments of the present application further provide a thin film, which adopts the following technical solutions:

[0009] A thin film is obtained by using the preparation method of the thin film as described above.

[0010] To solve the above technical problems, embodiments of the present application further provide an optoelectronic device, which adopts the following technical solutions:

[0011] An optoelectronic device includes:

[0012] a first electrode and a second electrode which are oppositely arranged;

[0013] a functional layer disposed between the first electrode and the second electrode;

[0014] wherein the functional layer includes at least one functional sub-layer, and at least one of the functional sub-layers includes a thin film obtained by using the preparation method of the thin film as described above, or the thin film as described above.

[0015] To solve the above technical problems, embodiments of the present application further provide a display device, which adopts the following technical solutions:

[0016] A display device includes the optoelectronic device as described above.

[0017] Compared with the prior art, the embodiments of the present application mainly have the following beneficial effects: By using the first energy treatment, the concentration of charged nanoparticles in the saturated solution during deposition is maintained constant, thereby improving the film formation uniformity of the thin film. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the solution of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following-described drawings are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 is a flowchart of the method for preparing a thin film according to an embodiment of the present application;

[0020] Figure 2 is a schematic structural diagram of an optoelectronic device according to an embodiment of the present application;

[0021] Reference numerals:

[0022] 210, first electrode; 220, hole injection layer; 230, hole transport layer; 240, quantum dot light-emitting layer; 250, electron transport layer; 260, electron injection layer; 270, second electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application or the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0024] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0025] Refer to Figure 1 , an embodiment of the present application provides a method for preparing a thin film, including:

[0026] Step S110, providing a saturated solution, the saturated solution including charged nanoparticles.

[0027] In some embodiments, the temperature of the saturated solution is 0-60° C. This ensures the material stability of the nanoparticles.

[0028] Optionally, the temperature of the saturated solution is selected from the range formed by any one or two of 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, and 60°C.

[0029] In some embodiments, the above step S110, before the step of providing a saturated solution, further includes the following steps:

[0030] Step S111, providing an initial saturated solution, wherein the initial saturated solution includes nanoparticles.

[0031] In some embodiments, the nanoparticles include a metal oxide material connected with a first ligand. In this case, the metal oxide material may be one of a hole injection material, a hole transport material, an electron transport material, and an electron injection material.

[0032] Furthermore, the first ligand includes at least one of a first carboxylic acid ligand, a sulfonic acid ligand, a first phosphate ligand, a first thiol ligand, an amine-containing ligand, a phosphorus-containing ligand, a betaine ligand, an acetylacetone ligand, a fluoroborate, a fluorophosphate, and a halogen.

[0033] Optionally, the first carboxylic acid ligand includes at least one of oleic acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, potassium hydrogen phthalate, salicylic acid, o-phenanthroline, tetraacetic acid, boric acid, citric acid, succinic acid, malonic acid, succinic acid, adipic acid, and sodium hydrogen oxalate.

[0034] Optionally, the sulfonic acid ligand includes at least one of benzenesulfonic acid, methylsulfonic acid, ethylsulfonic acid, aminosulfonic acid, methoxybenzenesulfonic acid, nitrobenzenesulfonic acid, hydroxybenzenesulfonic acid, aminobenzenesulfonic acid, 2-aminopyridine-5-sulfonic acid, 2-pyridinesulfonic acid, aminoethanesulfonic acid, and aminomethanesulfonic acid.

[0035] Optionally, the first phosphate ligand includes at least one of phosphorus trichloride, phosphorus pentachloride, triphenylphosphine, tri-tert-butylphosphine, tripropylphosphine, triethylphosphine, tributylphosphine, ferrocenephosphine, triphosphine ligand, diethylferrocenephosphine, dibutylferrocenephosphine, diphenylferrocenephosphine, diphenyl phosphoric acid, dimethyl diphenyl phosphoric acid, diethyl diphenyl phosphoric acid, and dipropyl diphenyl phosphoric acid.

[0036] Optionally, the first thiol ligand includes at least one of octyl mercaptan, 1-octadecanethiol, 1-dodecyl mercaptan, methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, methyl benzene mercaptan, and p-methoxy benzene mercaptan.

[0037] Optionally, the amine-containing ligand includes at least one of ethylamine, diethylamine, triethylamine, tetraethylamine, p-toluidine, and p-aminophenylamine.

[0038] Optionally, the phosphorus-containing ligand includes at least one of phosphorus trichloride, phosphorus pentachloride, diethyl phosphate, dimethyl phosphate, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, triphenyl phosphate, triphenylphosphonium, phosphatidic acid, dipalmitoyl phosphatidic acid, sphingosine, sphinganine, 1-octadecyl-2-hydroxy-3-propylphosphocholine, 1-octadecyl-2-hydroxy-3-propylphosphocholine ammonium salt, polyethylene glycol-phosphatidylethanolamine, and polyethylene glycol-phosphatidylcholine.

[0039] Optionally, the betaine ligand includes at least one of N-methyl-D-mannitol-1,2-propanediol betaine, N-ethyl-D-mannitol-1,2-propanediol betaine, N,N-dimethyl-N-hexadecylammonium chloride, and N,N-dimethyl-N-eicosylammonium chloride.

[0040] Furthermore, the metal oxide material includes at least one of doped or undoped molybdenum oxide, tungsten oxide, nickel oxide, copper oxide, zinc oxide, barium oxide, aluminum oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, manganese oxide, rhenium oxide, indium oxide, hafnium oxide, and niobium oxide, and the doping elements include at least one of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, gadolinium, tin, europium, erbium, thulium, gallium, and titanium.

[0041] Furthermore, the average particle size of the metal oxide material is 1 to 200 nm.

[0042] Optionally, the average particle size of the metal oxide material is selected from any one or any range formed by any two of 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, and 200 nm.

[0043] In some other embodiments, the nanoparticle includes a quantum dot material connected with a second ligand.

[0044] Furthermore, the second ligand includes at least one of a second carboxylic acid ligand, a second phosphoric acid ligand, and a second thiol ligand.

[0045] Optionally, the material selection range of the second carboxylic acid ligand is the same as that of the above-mentioned first carboxylic acid ligand, and no further elaboration is made here.

[0046] Optionally, the material selection range of the second phosphoric acid ligand is the same as that of the above-mentioned second phosphoric acid ligand, and no further elaboration will be made here.

[0047] Optionally, the material selection range of the second thiol ligand is the same as that of the above-mentioned first thiol ligand, and no further elaboration will be made here.

[0048] Further, the quantum dot material includes at least one of single-structure quantum dots and core-shell structure quantum dots. The material of the single-structure quantum dots, the core material of the core-shell structure quantum dots, and the shell material of the core-shell structure quantum dots are each independently selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds, I-III-VI group compounds, perovskite nanoparticle materials, and carbon quantum dots. The core-shell structure quantum dots include one or more layers. Among them, the II-VI group compounds are selected from at least one of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds are selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V group compounds are selected from at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, or InAlPSb; the I-III-VI group compounds are selected from at least one of CuInS2, CuInSe2, and AgInS2; the perovskite nanoparticle material is at least one of inorganic perovskite quantum dots, organic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots. Among them, the structural general formula of the inorganic perovskite quantum dots is AMX3, where A is Cs + ions, M is a divalent metal cation, and M is selected from Pb 2+, Sn 2+ , Cu 2+ , Ni 2+ , Cd 2 + , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ and Eu 2+ One or more of the following, X is a halogen anion; the structural general formula of the organic perovskite quantum dots is CMY3, C is formamidinium, and Y is a halogen anion; the structural general formula of the organic-inorganic hybrid perovskite quantum dots is BMZ3, B is selected from organic amine cations, and Z is a halogen anion.

[0049] In some embodiments, the initial saturated solution further includes a solvent selected from at least one of water, alcohol compounds, ether compounds, ester compounds, and alkane compounds.

[0050] Optionally, the alcohol solvents include at least one of methanol, ethanol, isopropanol, propanol, butanol, isobutanol, sec-butanol, tert-butanol, pentanol, 2-methyl-1-butanol, isopentanol, sec-pentanol, 3-pentanol, tert-pentanol, 3-methyl-2-butanol, neopentanol, hexanol, 4-methyl-2-pentanol, 2-hexanol, 2-ethylbutanol, 2-methylpentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-ethyl-3-pentanol, 3-hexanol, 4-methyl-1-pentanol, 3,3-dimethyl-2-butanol, heptanol, 2-heptanol, 3-heptanol, 2-methyl-3-hexanol, octanol, 2-octanol, 2-ethylhexanol, 2,5-dimethyl-2,5-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 4-methyl-3-heptanol, 3,5,5-trimethylhexanol, nonanol, 2-nonanol, 3-nonanol, 2,6-dimethyl-4-heptanol, decanol, undecanol, 5-ethyl-2-nonanol, dodecanol, trimethylnonanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, cyclopentanol, cyclohexanol, benzyl alcohol, propylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-2-propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, neopentyl glycol, 1,5-pentanediol, methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, isobutoxyethanol.

[0051] Optionally, the ether solvent includes at least one of diethyl ether, propylene oxide, diethyl ether, dibutyl ether, ethyl phenyl ether, dimethyl phenyl ether, diethyl phenyl ether, dipentyl phenyl ether, diisopropyl phenyl ether, phenyl diethyl ether, phenyl dichloroethane, phenyl dimethyl chloromethane, phenyl diisopropyl chloromethane, phenyl methyl ether, phenyl methyl chloroethane, phenyl methyl isopropyl chloromethane, phenyl ethyl chloromethane, phenyl ethyl isopropyl chloromethane, phenyl propyl chloromethane, phenyl isopropyl chloromethane, phenyl cyclohexyl chloromethane, ethoxyethane, propoxyethane, butoxyethane, isobutoxyethane, diethoxyethane, triethoxyethane, tetraethoxyethane, dipropoxyethane, tripropoxyethane, tetrapropoxyethane, dibutoxyethane, tributoxyethane, tetrabutoxyethane, diisobutoxyethane, dipentyloxyethane, tripentyloxyethane, tetrapentyloxyethane, dihexyloxyethane, methyl propyl ether, methyl butyl ether, methyl pentyl ether, methyl hexyl ether, methyl heptyl ether, methyl octyl ether, methyl nonyl ether, methyl decyl ether.

[0052] Optionally, the ester solvent includes at least one of methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, isopentyl acetate, hexyl acetate, heptyl acetate, octyl acetate, nonyl acetate, decyl acetate, dodecyl acetate, hexadecyl acetate, stearyl acetate, isostearyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, isopentyl propionate, hexyl propionate, heptyl propionate, octyl propionate, nonyl propionate, decyl propionate, dodecyl propionate, hexadecyl propionate, stearyl propionate, isostearyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, pentyl butyrate, isopentyl butyrate, hexyl butyrate, heptyl butyrate, octyl butyrate, nonyl butyrate, decyl butyrate, dodecyl butyrate, hexadecyl butyrate, stearyl butyrate, isostearyl butyrate, methyl valerate, ethyl valerate, propyl valerate, butyl valerate, pentyl valerate, isopentyl valerate, hexyl valerate, heptyl valerate, octyl valerate, nonyl valerate, decyl valerate, dodecyl valerate, hexadecyl valerate, stearyl valerate, isostearyl valerate, methyl caproate, ethyl caproate, propyl caproate, butyl caproate, pentyl caproate, isopentyl caproate, hexyl caproate, heptyl caproate, octyl caproate, nonyl caproate, decyl caproate, dodecyl caproate, hexadecyl caproate, stearyl caproate, isostearyl caproate.

[0053] Optionally, the alkanes solvent includes at least one of ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, methylethane, methylpropane, methylbutane, methylpentane, methylhexane, methylheptane, methyloctane, methylnonane, methyldecane, ethylethane, ethylpropane, ethylbutane, ethylpentane, ethylhexane, ethylheptane, ethyloctane, ethylnonane, ethyldecane, propylethane, propylpropane, propylbutane, propylpentane, propylhexane, propylheptane, propyloctane, propylnonane, propyldecane, butylethane, butylpropane, butylbutane, butylpentane, butylhexane, butylheptane, butyloctane, butylnonane, butyldecane, pentylethane, pentylpropane, pentylbutane, pentylpentane, pentylhexane, pentylheptane, pentyloctane, pentylnonane, pentyldecane, hexylethane, hexylpropane, hexylbutane, hexylpentane, hexylhexane, hexylheptane, hexyloctane, hexylnonane, hexyldecane.

[0054] Step S112: Perform a second energy treatment on the initial saturated solution to obtain a saturated solution including the charged nanoparticles.

[0055] In this step, by performing a second energy treatment on the initial saturated solution, the ligands on the surface of the nanoparticles are promoted to fall off, so that the surface of the nanoparticles becomes charged, forming charged nanoparticles.

[0056] In some embodiments, the second energy treatment is a second ultrasonic treatment.

[0057] In some embodiments, the power density of the second ultrasonic treatment is 0.2 - 10 W / cm 2 .

[0058] Optionally, the power density of the second ultrasonic treatment is selected from 0.2 W / cm 2 , 0.5 W / cm 2 , 1 W / cm 2 , 1.5 W / cm 2 , 2 W / cm 2 , 2.5 W / cm 2 , 3 W / cm 2 , 3.5 W / cm 2 , 4 W / cm 2 , 4.5 W / cm 2 , 5 W / cm 2 , 5.5 W / cm 2 , 6 W / cm 2 , 6.5 W / cm 2 , 7 W / cm 2, 7.5 W / cm 2 , 8 W / cm 2 , 8.5 W / cm 2 , 9 W / cm 2 , 9.5 W / cm 2 , 10 W / cm 2 The range formed by any one or any two of them.

[0059] In some embodiments, the ultrasonic frequency of the second ultrasonic treatment is 20 - 200 KHz.

[0060] Optionally, the ultrasonic frequency of the second ultrasonic treatment is selected from the range formed by any one or any two of 20 KHz, 40 KHz, 60 KHz, 80 KHz, 100 KHz, 120 KHz, 140 KHz, 160 KHz, 180 KHz, 200 KHz.

[0061] In some embodiments, the time of the second ultrasonic treatment is 1 - 300 min.

[0062] Optionally, the time of the second ultrasonic treatment is the range formed by any one or any two of 1 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, 240 min, 250 min, 260 min, 270 min, 280 min, 290 min, 300 min.

[0063] Understandably, within the power density, ultrasonic frequency and time of the above second ultrasonic treatment, the detachment efficiency of ligands on the nanoparticles can be improved, ensuring the number of charged nanoparticles in the initial saturated solution, providing a stable electrophoresis environment for the concentration of charged nanoparticles in the initial saturated solution for film formation, thereby improving the film formation uniformity.

[0064] In some embodiments, the temperature of the second ultrasonic treatment is 25 - 100 °C. Within this range, the ionization efficiency of ligands on the nanoparticles can be improved, and damage to the nanoparticles can be avoided.

[0065] Optionally, the temperature of the second ultrasonic treatment is the range formed by any one or any two of 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C.

[0066] In some embodiments, before the step of performing the second ultrasonic treatment on the initial saturated solution in step S112, the method further includes: adding a buffer to the initial saturated solution.

[0067] In this embodiment, a buffer is used to adjust the ionic strength and electrolyte concentration of the initial saturated solution, thereby reducing the adverse effects of the heat energy and mechanical energy generated during the second ultrasonic treatment on the stability of the particle core structure, and further enhancing the structural stability of the nanoparticles during the second ultrasonic treatment.

[0068] Optionally, the buffer includes at least one of tris(hydroxymethyl)aminomethane hydrochloride, phosphate, HEPES, carbonate, acetate, citrate, TAE, TBE, morpholineethanesulfonic acid, 3-morpholinopropanesulfonic acid, glycine, HEPES-KOH, N,N-bis(2-hydroxyethyl)glycine, 3-(cyclohexylamino)-1-propanesulfonic acid, SDS-PAGE, carbamide, formate, propionate, butyrate, lactate.

[0069] In some embodiments, the concentration of the buffer in the initial saturated solution is 0.0001 - 1 mmol / L.

[0070] Optionally, the concentration of the buffer in the initial saturated solution is any one or any range formed by any two of 0.0001 mmol / L, 0.0005 mmol / L, 0.001 mmol / L, 0.005 mmol / L, 0.01 mmol / L, 0.05 mmol / L, 0.1 mmol / L.

[0071] Step S120: Applying an electric field treatment and a first energy treatment to the saturated solution to obtain a thin film.

[0072] In practical applications, two electrodes with opposite polarities are provided, one as the positive electrode and the other as the negative electrode. After attaching the preform to one of the electrodes, the two electrodes are immersed in the saturated solution. When an electric current is applied, an electric field is generated in the saturated solution. Under the drive of the electric field, the charged nanoparticles (positively charged / negatively charged) on the surface migrate towards the preform (negative electrode side / positive electrode side), and thus a thin film is deposited on the preform.

[0073] It can be understood that in the present invention, a saturated solution is used. When performing the first energy treatment on the saturated solution, the ligands on the surface of the nanoparticles in the saturated solution continue to fall off and become charged, replenishing the charged nanoparticles lost due to electric field deposition, thereby maintaining the constancy of the concentration of the charged nanoparticles in the saturated solution, further enhancing the film formation uniformity and denseness. And if there is already a film layer on the preform, it can improve the interface contact between the existing film layer on the preform and the electrophoretic deposition film layer, and enhance the connection strength between the film layers.

[0074] Exemplarily, when the present invention is applied to the preparation of optoelectronic devices, the preform may include not only a substrate but also other film layers; for example:

[0075] ① When the nanoparticles are hole injection materials, the preform may further include a first electrode disposed on the substrate;

[0076] ② When the nanoparticles are hole transport materials, the preform may further include a first electrode disposed on the substrate, or a first electrode and a hole injection layer stacked on the substrate;

[0077] ③ When the nanoparticles are quantum dot materials, the preform may further include a first electrode disposed on the substrate, or a first electrode, a hole injection layer and / or a hole transport layer stacked on the substrate.

[0078] ④ When the nanoparticles are electron transport materials, the preform may further include a first electrode and a quantum dot light-emitting layer stacked on the substrate, or a first electrode, a hole injection layer and / or a hole transport layer, and a quantum dot light-emitting layer stacked on the substrate.

[0079] ⑤ When the nanoparticles are electron injection materials, the preform may further include a first electrode and a quantum dot light-emitting layer stacked on the substrate, or a first electrode, a hole injection layer and / or a hole transport layer, and a quantum dot light-emitting layer stacked on the substrate, or a first electrode, a hole injection layer and / or a hole transport layer, a quantum dot light-emitting layer, and an electron transport layer stacked on the substrate.

[0080] In some embodiments, the first energy treatment includes a first ultrasonic treatment, and the power density of the first ultrasonic treatment is 0.1 - 5 W / cm 2 . Thus, by performing the first ultrasonic treatment on the saturated solution with a weak ultrasonic wave having a power density of 0.1 - 5 W / cm 2 , the film layers already deposited on the preform can be prevented from being damaged by the ultrasonic impact of too high power density, thereby ensuring the film formation quality.

[0081] Optionally, the power density of the first ultrasonic treatment is selected from any one or any two of 0.1 W / cm 2 , 0.5 W / cm 2 , 1 W / cm 2 , 1.5 W / cm 2 , 2 W / cm 2 , 2.5 W / cm 2 , 3 W / cm 2 , 3.5 W / cm 2 , 4 W / cm 2 , 4.5 W / cm 2 , 5 W / cm 2 to form a range.

[0082] In some embodiments, the power density of the first ultrasonic treatment is less than that of the second ultrasonic treatment. The first ultrasonic treatment with a relatively high power density can form sufficient charged nanoparticles in the saturated solution before deposition. Then, during deposition, the saturated solution is treated with the second ultrasonic treatment whose power density is less than that of the first ultrasonic treatment to supplement the charged nanoparticles in the saturated solution and avoid damage to the film layer already deposited on the preform due to ultrasonic impact at too high a power density, thereby ensuring the film-forming quality.

[0083] In some embodiments, the ultrasonic frequency of the first ultrasonic treatment is 20 - 200 KHz.

[0084] Optionally, the ultrasonic frequency of the first ultrasonic treatment is selected from any one or any range formed by any two of 20 KHz, 40 KHz, 60 KHz, 80 KHz, 100 KHz, 120 KHz, 140 KHz, 160 KHz, 180 KHz, 200 KHz.

[0085] In some embodiments, the temperature of the first ultrasonic treatment is 25 - 100 °C. Within this range, the ionization efficiency of the ligands on the nanoparticles in the saturated solution can be improved, and the nanoparticles can be prevented from being damaged.

[0086] Optionally, the temperature of the first ultrasonic treatment is any one or any range formed by any two of 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C.

[0087] In some embodiments, the duration of the electric field is 0.5 - 180 min.

[0088] Optionally, the duration of the electric field is selected from any one or any range formed by any two of 0.5 min, 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min, 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, 150 min, 155 min, 160 min, 165 min, 170 min, 175 min, 180 min.

[0089] In some embodiments, the electric field strength in the electric field treatment is 1x10 4 ~1x108 V / m.

[0090] Optionally, the electric field strength in the electric field treatment is 1x10 4 V / m, 3x10 4 V / m, 6x10 4 V / m, 1x10 5 V / m, 3x10 5 V / m, 6x10 5 V / m, 1x10 6 V / m, 3x10 6 V / m, 6x10 6 V / m, 1x10 7 V / m, 3x10 7 V / m, 6x10 7 V / m, 1x10 8 V / m, or any range formed by any one or both of them.

[0091] Understandably, the thickness and quality of the metal oxide film layer can be controlled by changing the intensity and duration of the electric field applied on both sides of the electrode.

[0092] In some embodiments, in the above step S120, the step of applying an electric field to the saturated solution and performing the first ultrasonic treatment includes one of the following:

[0093] ① Apply an electric field treatment to the saturated solution and perform a first energy treatment in sequence. By first applying an electric field to the saturated solution to consume the charged nanoparticles in the saturated solution, and then performing a first energy treatment on the saturated solution to form charged nanoparticles in the saturated solution, thereby replenishing the charged nanoparticles lost due to electric field deposition. In this way, while maintaining the concentration of charged nanoparticles in the saturated solution, the situation of having an excessive amount of charged nanoparticles in the saturated solution can be avoided.

[0094] ② Perform a first energy treatment on the saturated solution and apply an electric field treatment in sequence. By first performing a first energy treatment on the saturated solution to form charged nanoparticles in the saturated solution, so that there are sufficient charged nanoparticles in the saturated solution. Then, when applying an electric field to drive the deposition of charged nanoparticles, the film formation uniformity and density can be effectively ensured.

[0095] ③ Apply an electric field treatment to the saturated solution and perform a first energy treatment on the saturated solution, so that while driving the deposition of charged nanoparticles through the electric field, the first ultrasonic treatment is used to form charged nanoparticles in the saturated solution, timely replenishing the charged nanoparticles lost due to electric field deposition, maintaining the constancy of the concentration of charged nanoparticles in the saturated solution, and further improving the film formation uniformity and density.

[0096] In some embodiments, in the above step S120, during the process of applying an electric field treatment and performing a first energy treatment on the saturated solution, the electric field treatment is performed within a first time period, and the first energy treatment is performed within a second time period. The first time period and the second time period are any of the following situations:

[0097] (a) The first time period and the second time period completely overlap, and the duration of the second time period is greater than the duration of the first time period. In this way, when an electric field is applied to the saturated solution, the saturated solution is treated by first ultrasonic treatment, so as to further ensure the constancy of the concentration of charged nanoparticles in the saturated solution, and further improve the film forming uniformity and denseness.

[0098] (b) The first time period and the second time period partially overlap. In this way, while maintaining the constancy of the concentration of charged nanoparticles in the saturated solution, the formation of excessive charged nanoparticles in the saturated solution can be avoided.

[0099] (c) The first time period and the second time period do not overlap at all. In this way, it is convenient for the operator to better control and adjust the process parameters, which helps to improve the controllability and stability of the preparation process.

[0100] In some embodiments, in the above step S130, the steps of applying an electric field treatment and performing a first energy treatment on the saturated solution include:

[0101] Apply an electric field treatment and perform a first energy treatment on the saturated solution, and add an acidic material to the saturated solution.

[0102] It can be understood that by adding an acidic material to the saturated solution, hydrogen atoms are introduced into the saturated solution, and the first ligand / second ligand on the surface of the nanoparticles in the saturated solution is protonated to make it fall off, so as to improve the falling-off efficiency of the ligand during the first ultrasonic treatment, ensure that the saturated solution has enough charged nanoparticles, and further improve the film forming uniformity of the thin film.

[0103] In some embodiments, the acidic solution is selected from at least one of HCl, H2SO4, HClO4, HNO3, HClO3, HClO2, HClO, LiClO4, NaClO4, KClO4.

[0104] In some embodiments, the concentration of the acidic material in the saturated solution is 0.0001 - 0.1 mmol / L. Within this range, hydrogen atoms can be introduced into the saturated solution to improve the falling-off efficiency of the ligand, and at the same time, the film layer deposited on the preform is also prevented from being corroded and damaged.

[0105] Optionally, the concentration of the acidic material in the saturated solution is any one or any range formed by any two of 0.0001 mmol / L, 0.0005 mmol / L, 0.001 mmol / L, 0.005 mmol / L, 0.01 mmol / L, 0.05 mmol / L, and 0.1 mmol / L.

[0106] In some embodiments, in step S130, after the step of obtaining the thin film, the method further includes:

[0107] Taking out the thin film from the saturated solution;

[0108] Performing a cleaning treatment and a drying treatment on the thin film in sequence.

[0109] In this step, the saturated solution attached to the thin film is removed through the cleaning treatment, and after the cleaning treatment, the solvent used in the cleaning treatment is removed by the drying treatment.

[0110] In some embodiments, the solvent used in the cleaning treatment has the same selection range as the solvent in the saturated solution, which will not be elaborated further herein.

[0111] In some embodiments, the temperature of the drying treatment is 40 - 250 °C.

[0112] Optionally, the temperature of the drying treatment is selected from any one or any range formed by any two of 40 °C, 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C, and 250 °C.

[0113] In some embodiments, the time of the drying treatment is 1 - 300 min.

[0114] Optionally, the time of the drying treatment is selected from any one or any range formed by any two of 1 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min, 210 min, 220 min, 230 min, 240 min, 250 min, 260 min, 270 min, 280 min, 290 min, and 300 min.

[0115] The embodiment of the present application further provides a thin film, which is prepared by using the above-mentioned method for preparing a thin film.

[0116] In this embodiment, the thin film is one of a hole transport layer, a hole injection layer, an electron transport layer, an electron injection layer, and a quantum dot light-emitting layer.

[0117] In the preparation of the thin film, the present invention uses a saturated solution. When performing a first energy treatment on the saturated solution, the ligands on the surface of the nanoparticles in the saturated solution continue to fall off and become charged, supplementing the charged nanoparticles lost due to electric field deposition, so as to maintain the constancy of the concentration of charged nanoparticles in the saturated solution, thereby improving the film formation uniformity and density. And if a film layer is already provided on the preform, it can improve the interfacial contact between the existing film layer on the preform and the electrophoretic deposition film layer, and enhance the connection and composite strength between the film layers.

[0118] Refer to Figure 2 , the embodiment of the present application further provides an optoelectronic device, including:

[0119] A first electrode 210 and a second electrode 270 which are oppositely arranged;

[0120] A functional layer disposed between the first electrode 210 and the second electrode 270.

[0121] Wherein, the functional layer includes at least one functional sub-layer, and at least one of the functional sub-layers includes a thin film prepared by using the above-mentioned method for preparing a thin film, or is the above-mentioned thin film.

[0122] In this embodiment, in the preparation of the thin film, the present invention uses a saturated solution. When performing a first energy treatment on the saturated solution, the ligands on the surface of the nanoparticles in the saturated solution continue to fall off and become charged, supplementing the charged nanoparticles lost due to electric field deposition, so as to maintain the constancy of the concentration of charged nanoparticles in the saturated solution, thereby improving the film formation uniformity and density. And if a film layer is already provided on the preform, it can improve the interfacial contact between the existing film layer on the preform and the electrophoretic deposition film layer, and enhance the connection and composite strength between the film layers.

[0123] In some embodiments, at least one of the functional sub-layers is one of a quantum dot light-emitting layer, a hole functional layer, and an electron functional layer.

[0124] Exemplarily, the functional layer includes five functional sub-layers, namely a hole injection layer 220, a hole transport layer 230, a quantum dot light-emitting layer 240, an electron transport layer 250, and an electron injection layer 260. The hole injection layer 220, the hole transport layer 230, the quantum dot light-emitting layer 240, the electron transport layer 250, and the electron injection layer 260 are sequentially stacked on the first electrode 210, and the second electrode 220 is disposed on a side of the electron injection layer 260 away from the electron transport layer 250.

[0125] In some embodiments, when the hole injection layer 220 and / or the hole transport layer 230 is not the thin film, the materials of the hole transport layer 230 and / or the hole injection layer 220 include at least one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal stannides, doped graphene, undoped graphene, and C60.

[0126] In some embodiments, when the electron transport layer 250 and / or the electron injection layer 260 is not the thin film, the materials of the electron transport layer 250 and the electron injection layer 260 independently include inorganic materials and / or organic materials; the inorganic materials include one or more of doped or undoped zinc oxide, barium oxide, aluminum oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanate oxide, aluminum zinc oxide, manganese zinc oxide, tin zinc oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, barium titanate, and the doped elements include at least one of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; the organic materials include at least one of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds, polythiophene compounds, perylene diimide compounds, and fullerene compounds.

[0127] The embodiment of the present application further provides a display device including the optoelectronic device as described above.

[0128] In this embodiment, the display device includes the functional sub-layer of the optoelectronic device as described above. When preparing the thin film included in the functional sub-layer, a saturated solution is used, and the first energy treatment is performed on the saturated solution, so that the ligands on the surface of the nanoparticles in the saturated solution continue to fall off and become charged, supplementing the charged nanoparticles lost due to the electric field deposition, thereby maintaining the constancy of the concentration of the charged nanoparticles in the saturated solution, and further improving the film formation uniformity and compactness. And if a film layer is already provided on the preform, the interface contact between the existing film layer on the preform and the electrophoretic deposition film layer can be improved, and the strength of the connection and combination between the film layers can be enhanced.

[0129] The technical solutions and technical effects of the present application will be described in detail below through specific embodiments and comparative examples. The following embodiments are only partial embodiments of the present application and do not specifically limit the present application.

[0130] Thin film Example 1:

[0131] Step 1: Provide a substrate and a saturated solution of molybdenum oxide nanoparticles dissolved in a n-butanol solution and using oleic acid as a surface ligand;

[0132] Step 2: First perform the first ultrasonic treatment on the saturated solution, where the temperature of the first ultrasonic treatment is 45 °C, the frequency is 30 KHz, and the power density is 5 W / cm 2 , and then immerse the ITO substrate substrate connected to the negative electrode of the power supply and another conductive substrate connected to the positive electrode of the power supply in parallel in the saturated solution to apply an electric field to the saturated solution, where the electric field strength between the two parallel plates is maintained at 3×10 5 V / m, and the duration of the first ultrasonic treatment and the electric field is 25 min.

[0133] Step 3: Take out the deposited ITO substrate, and while maintaining the voltage bias, immerse it in a solvent and rinse for 100 s. Subsequently, place the substrate in a drying oven at a certain temperature of 100 °C for 30 min, and finally the obtained thin film is a hole functional layer.

[0134] Thin film Example 2:

[0135] The difference from Example 1 is that in Step 2 of this Example 1, an electric field is first applied to the saturated solution, and then the first ultrasonic treatment is performed on the saturated solution.

[0136] Thin film Example 3:

[0137] The difference from Example 1 is that in Step 2 of this Example 1, when performing the first ultrasonic treatment on the saturated solution, the first ultrasonic treatment is also performed on the saturated solution.

[0138] Thin film Example 4:

[0139] The difference from Example 1 is that in Step 2 of this Example 1, the duration of the first ultrasonic treatment is changed to 15 min.

[0140] Film Example 5:

[0141] The difference from Example 1 is that after Step 1 of this Example and before Step 2, it further includes performing a second ultrasonic treatment on the saturated solution, where the temperature of the second ultrasonic treatment is 45°C, the frequency is 60 KHz, the power density is 6 W / cm 2 , and the time is 30 min.

[0142] Film Example 6:

[0143] The difference from Film Example 5 is that before performing the second ultrasonic treatment on the saturated solution, a Hepes buffer is added to the saturated solution, where the concentration of the Hepes buffer in the saturated solution is 0.25 mmol / L.

[0144] Film Example 7:

[0145] The difference from Film Example 6 is that the concentration of the Hepes buffer in the saturated solution is changed to 0.0001 mmol / L.

[0146] Film Example 8:

[0147] The difference from Film Example 6 is that the concentration of the Hepes buffer in the saturated solution is changed to 1 mmol / L.

[0148] Film Example 9:

[0149] The difference from Film Example 6 is that the Hepes buffer is changed to a MOPS buffer.

[0150] Film Example 10:

[0151] The difference from Film Example 5 is that the power density of the second ultrasonic treatment is changed to 8 W / cm 2 .

[0152] Film Example 11:

[0153] The difference from Film Example 5 is that the power density of the second ultrasonic treatment is changed to 10 W / cm 2 .

[0154] Film Example 12:

[0155] The difference from Film Example 1 is that in Step 2 of this Example, the power density of the first ultrasonic treatment is changed to 1 W / cm 2 .

[0156] Film Example 13:

[0157] The difference from Film Example 1 is that in Step 2 of this example, the power density of the first ultrasonic treatment is changed to 0.1 W / cm 2 .

[0158] Film Example 14:

[0159] The difference from Film Example 1 is that in Step 3 of this example, before the step of immersing the ITO substrate in parallel with another conductive substrate connected to the positive electrode of the power supply in the above ink, HCl is added to the saturated solution, and the concentration of HCl in the saturated solution is 0.0001 mmol / L.

[0160] Film Example 15:

[0161] The difference from Film Example 14 is that in Step 3 of this example, the concentration of HCl in the saturated solution is changed to 0.01 mmol / L.

[0162] Film Example 16:

[0163] The difference from Film Example 14 is that in Step 3 of this example, the concentration of HCl in the saturated solution is changed to 0.1 mmol / L.

[0164] Film Example 17:

[0165] The difference from Film Example 14 is that HCL is changed to HClO.

[0166] Film Example 18:

[0167] The difference from Film Example 1 is that in Step 1 of this example, molybdenum oxide nanoparticles are changed to tungsten oxide nanoparticles.

[0168] Film Example 19:

[0169] The difference from Film Example 1 is that in Step 1 of this example, molybdenum oxide nanoparticles are changed to zinc oxide nanoparticles; correspondingly, in Step 4 of this example, the finally obtained film is an electronic functional layer.

[0170] Film Example 20:

[0171] The difference from Film Example 19 is that in Step 1 of this example, zinc oxide nanoparticles are changed to tin dioxide nanoparticles.

[0172] Film Example 21:

[0173] The difference from Thin Film Example 1 is as follows: In step one of this example, the saturated solution is formed by dispersing CdSe / ZnS core / shell structure quantum dots modified with triphenylphosphine as a surface ligand at a supersaturated concentration in an n-octane solution; correspondingly, in step four of this example, the finally obtained thin film is a quantum dot light-emitting layer.

[0174] Thin Film Example 22:

[0175] The difference from Thin Film Example 21 is that in step one of this example, "CdSe / ZnS core / shell structure quantum dots modified with triphenylphosphine as a surface ligand" is modified to "CdSe single structure quantum dots modified with acetate as a surface ligand".

[0176] Thin Film Comparative Example 1:

[0177] The difference from Thin Film Example 1 is that in step one of the comparative example, the saturated solution is omitted, and a functional solution of molybdenum oxide nanoparticles with a concentration of 60 mg / ml dissolved in 1 L of ethanol solution is provided. Correspondingly, in step three of the comparative example, the second ultrasonic treatment step is omitted, and the ITO substrate is connected to the negative electrode of the power supply and immersed in parallel with another conductive substrate connected to the positive electrode of the power supply in the functional solution, where the electric field strength between the two parallel plates is maintained at 3x10 5 V / m, and the duration of the electric field is 25 min.

[0178] Thin Film Comparative Example 2:

[0179] The difference from Thin Film Comparative Example 1 is that in step one of this comparative example, molybdenum oxide nanoparticles are changed to tungsten oxide nanoparticles.

[0180] Thin Film Comparative Example 3:

[0181] The difference from Thin Film Comparative Example 1 is that in step one of this comparative example, molybdenum oxide nanoparticles are changed to zinc oxide nanoparticles; correspondingly, in step three of this comparative example, the finally obtained thin film is an electron functional layer.

[0182] Thin Film Comparative Example 4:

[0183] The difference from Thin Film Comparative Example 3 is that in step one of this comparative example, zinc oxide nanoparticles are changed to tin dioxide nanoparticles.

[0184] Thin Film Comparative Example 5:

[0185] The difference from Thin Film Comparative Example 1 is that in step one of this comparative example, CdSe / ZnS core-shell structure quantum dots modified with triphenylphosphine as a surface ligand are dissolved in an n-octane solution at a concentration of 45 mg / ml to obtain a quantum dot ink; correspondingly, in step three of this comparative example, the finally obtained thin film is a quantum dot functional layer.

[0186] Thin film comparative example 6:

[0187] The difference from thin film comparative example 5 is that in step 1 of this comparative example, "CdSe / ZnS core / shell structure quantum dots modified with triphenylphosphine as a surface ligand" is modified to "CdSe single structure quantum dots modified with acetate as a surface ligand".

[0188] Experimental test analysis: Mobility tests and roughness tests were respectively carried out on the thin films prepared in thin film examples 1 to 16 and thin film comparative examples 1 to 4. The test results are shown in Table 1.

[0189] Mobility test: The thin films prepared in thin film examples 1 to 20 and thin film comparative examples 1 to 4 were used to prepare single-carrier devices. The J-V relationship of the devices was tested by an IVL test device, and the mobility of the devices was obtained according to the fitting results of the SCLC region in the J-V curve.

[0190] Roughness test: The root mean square roughness (RMS) of the thin films prepared in thin film examples 1 to 22 and thin film comparative examples 1 to 6 was tested by an atomic force microscope (AFM).

[0191] Table 1

[0192]

[0193]

[0194] Referring to Table 1, it can be seen that by comparing thin film examples 1 to 22 and thin film comparative examples 1 to 6, the roughness of the single-carrier devices prepared in the thin film examples of the present invention is higher, indicating that in the examples of the present invention, a saturated solution is used, and the saturated solution is treated by the first ultrasonic treatment with a low power density. The thin film formed by electrophoretic deposition is flat and has a low roughness, thereby improving the uniformity and compactness of the thin film.

[0195] Secondly, by comparing Film Examples 1 to 20 and Film Comparative Examples 1 to 6, it can be seen that the mobility of the single-carrier devices prepared from the film examples of the present invention is higher, indicating that due to the higher uniformity and denseness of the films prepared from the examples of the present invention, the films of the present invention have higher mobility; moreover, by comparing "Film Examples 1 and 18 with Film Comparative Examples 1 and 2", "Film Examples 19 and 20 with Film Comparative Examples 3 and 4", and "Film Examples 21 and 22 with Film Comparative Examples 5 and 6", it can be seen that compared with the film comparative examples, the hole functional layer films, electron functional layer films, and quantum dot light-emitting layer films prepared from the examples of the present invention all have lower roughness and higher mobility, indicating that the examples of the present invention can be applied to the preparation of hole functional layers, electron functional layers, and quantum dot light-emitting layers, with wide generality.

[0196] Further, ① continue to refer to Table 1. By comparing Film Example 1 and Film Example 5, it can be seen that before electrophoretic deposition, the saturated solution is subjected to a second ultrasonic treatment to make the saturated solution contain sufficient charged nanoparticles, so that the film obtained after electrophoretic deposition in Film Example 5 has higher mobility and lower roughness compared with Film Example 1.

[0197] ② continue to refer to Table 1. By comparing Film Examples 5 to 9, it can be seen that before the saturated solution is subjected to a second ultrasonic treatment, Hepes buffer or MOPS buffer is added to adjust the ionic strength and electrolyte concentration of the saturated solution and maintain the structural stability of the charged nanoparticles under the first ultrasonic treatment, thereby improving the film-forming uniformity and denseness of the film prepared from the charged nanoparticles. Furthermore, compared with Film Example 5, the single-carrier devices prepared from Film Examples 6 to 9 have higher mobility and lower roughness. And since the Hepes buffer is alkaline and will corrode the film already deposited on the substrate, as the concentration of Hepes buffer in the saturated solution increases after addition, the mobility of Film Examples 6 to 9 shows a trend of increasing first and then decreasing, and the roughness shows a trend of decreasing first and then increasing.

[0198] ③ continue to refer to Table 1. By comparing Film Examples 5, 10, and 11, it can be seen that as the power density of the second ultrasonic treatment increases, the shedding of ligands on the nanoparticles can be further promoted, making the supersaturated solution contain more charged nanoparticles, thereby improving the film-forming uniformity and denseness of the film. Furthermore, compared with Film Example 5, Film Examples 10 and 11 have higher mobility and lower roughness. And the greater the power density of the second ultrasonic treatment, the greater the thermal energy and mechanical energy generated during the treatment, which affects the structural stability of the charged nanoparticles. Therefore, the greater the power density of the second ultrasonic treatment, the mobility of Film Examples 5, 10, and 11 shows a trend of increasing first and then decreasing, and the roughness shows a trend of decreasing first and then increasing.

[0199] Similarly, continue to refer to Table 1. By comparing Examples 1, 12, and 13 of the thin film, it can be seen that the influence on the thin film examples when the power density of the first ultrasonic treatment increases is the same as that when the power density of the second ultrasonic treatment increases, and no further elaboration will be made here.

[0200] ④ Continue to refer to Table 1. By comparing Examples 1, 14 to 16 of the thin film, it can be seen that by adding HCl to the saturated solution, when the saturated solution is subjected to the first ultrasonic treatment, the hydrogen atoms in HCl protonate the ligands on the surface of the nanoparticles, promoting the detachment and charging of the ligands on the nanoparticles, supplementing the charged nanoparticles lost due to electric field deposition, thereby maintaining the constancy of the concentration of charged nanoparticles in the saturated solution, and further improving the film formation uniformity and compactness. As a result, compared with Example 1 of the thin film, Examples 14 to 16 of the thin film have higher mobility and lower roughness; and since HCl will corrode the thin film already deposited on the substrate, as the concentration of HCl in the saturated solution increases after addition, the mobility of Examples 14 to 16 of the thin film first increases and then decreases, and the roughness first decreases and then increases.

[0201] Secondly, by comparing Examples 14 and 17 of the thin film, it can be seen that at the same concentration, since the acidity of HCl is stronger than that of HClO, compared with Example 14 corresponding to HClO, the thin film examples corresponding to HCl have higher mobility and lower roughness.

[0202] Optoelectronic device Example 1:

[0203] Step 1: Provide an ITO preform as the first electrode.

[0204] Step 2: Prepare a 10-nm hole functional layer by inkjet printing molybdenum oxide nanoparticle ink dispersed in a n-butanol solution at a concentration of 20 mg / ml, and dry it at 100 °C for 30 min.

[0205] Step 3: Prepare a quantum dot light-emitting layer on the hole functional layer by using the method of Example 21 of the thin film.

[0206] Step 4: Prepare a 25-nm electron functional layer by inkjet printing ZnO nanoparticle ink dispersed in a n-butanol solution at a concentration of 35 mg / ml on the quantum dot light-emitting layer, and dry it at 100 °C for 30 min.

[0207] Step 5: Prepare a 100-nm Ag material on the electron transport layer by evaporation to form the second electrode.

[0208] Optoelectronic device Examples 2 to 18:

[0209] The difference from the optoelectronic device Example 1 is that: in the second step of this Example n, the hole functional layer is prepared by the method of thin film Example n - 1, where n is any one of 2 to 18.

[0210] Optoelectronic device Example 19:

[0211] The difference from the optoelectronic device Example 1 is that: in the fourth step of this Example, the electron functional layer is prepared by the method of thin film Example 19.

[0212] Optoelectronic device Example 20:

[0213] The difference from the optoelectronic device Example 1 is that: in the second step of this Example, the hole functional layer is prepared by the method of thin film Example 1, and in the fourth step of this Example, the electron functional layer is prepared by the method of thin film Example 19.

[0214] Optoelectronic device Comparative Example 1:

[0215] The difference from the optoelectronic device Example 1 is that: in this Comparative Example, Step 3 is to provide CdSe / ZnS core / shell structure quantum dot ink dissolved in n - octane solution at a concentration of 45 mg / ml. The ITO prefabricated substrate is connected to the negative electrode of the power supply and immersed in parallel with another conductive prefabricated substrate connected to the positive electrode of the power supply in the above ink, where the electric field strength between the two parallel plates is maintained at 7x10 4 V / m for 25 min. Then the above parallel plates are taken out of the ink, and while maintaining the voltage bias, they are immersed in the solvent and rinsed for 30 s. The substrate is dried at a certain temperature of 100 °C for 30 min, and finally a 25 - nm quantum dot light - emitting layer is obtained.

[0216] Optoelectronic device Comparative Example 2:

[0217] The difference from the optoelectronic device Comparative Example 1 is that: in the second step of this Comparative Example, the hole functional layer is prepared by the method of thin film Comparative Example 1.

[0218] Optoelectronic device Comparative Example 3:

[0219] The difference from the optoelectronic device Comparative Example 1 is that: in the fourth step of this Comparative Example, the electron functional layer is prepared by the method of thin film Comparative Example 3.

[0220] Optoelectronic device Comparative Example 4:

[0221] The difference from the optoelectronic device Comparative Example 1 is that: in the second step of this Comparative Example, the hole functional layer is prepared by the method of thin film Comparative Example 1; in the fourth step of this Comparative Example, the electron functional layer is prepared by the method of thin film Comparative Example 3.

[0222] Functional Test: The luminous performance parameters of the device were tested through an IVL test device, and the CEmax (cd / A) and the service life T95 (h) of the device were obtained. Among them, CE max (cd / A): The maximum luminous efficiency. Service life T95 (h): By making the device light up at an initial brightness of 1000 cd / m 2 and evaluating the service life of the device by the duration T95 until the brightness decays to 95% of the initial brightness. The test results are shown in Table 2.

[0223] Table 2

[0224]

[0225]

[0226] Referring to Table 2, it can be seen that by comparing Example 1 of the optoelectronic device and Comparative Example 1 of the optoelectronic device, when the quantum dot light-emitting layer in Example 1 of the optoelectronic device of the present invention is prepared by the above thin film example, the optoelectronic device has a larger CE max and T95@1000 nit; it shows that because the quantum dot light-emitting layer prepared by the above thin film example has higher film-forming uniformity and denseness, the optoelectronic device containing the quantum dot light-emitting layer has better device performance.

[0227] Moreover, from "comparing Example 2 to 18 of the optoelectronic device and Comparative Example 2 of the optoelectronic device", "comparing Example 19 of the optoelectronic device and Comparative Example 3 of the optoelectronic device", and "comparing Example 20 of the optoelectronic device and Comparative Example 4 of the optoelectronic device", it can be seen that when the quantum dot light-emitting layer, hole functional layer, and / or electron functional layer in the optoelectronic device prepared in the embodiments of the present invention are prepared by electrophoresis using a saturated solution and subjected to the first ultrasonic treatment, the film-forming uniformity and denseness of the prepared film layer can be further improved, thereby further improving the CE max and T95@1000 nit of the optoelectronic device.

[0228] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The preferred embodiments of the present application are given in the drawings, but do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure content of the present application more thorough and comprehensive. Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing specific embodiments, or perform equivalent replacements on some of the technical features. Any equivalent structure made by using the specification and drawings of the present application, directly or indirectly applied to other related technical fields, is similarly within the scope of patent protection of the present application.

Claims

1. A method for preparing a thin film, characterized in that, Comprising: Providing a saturated solution, the saturated solution comprising charged nanoparticles; Applying an electric field treatment and a first energy treatment to the saturated solution to obtain a thin film.

2. The method for preparing the thin film according to claim 1, wherein The first energy treatment includes first ultrasonic treatment, and the power density of the first ultrasonic treatment is 0.1 to 5 W / cm 2 ; and / or, The temperature of the saturated solution is 0 to 60 °C; and / or, During the process of applying the electric field treatment and the first energy treatment to the saturated solution, the electric field treatment is carried out within a first time period, and the first energy treatment is carried out within a second time period. The first time period and the second time period are any of the following situations: (a) The first time period and the second time period completely overlap, and the duration of the second time period is greater than the duration of the first time period; (b) The first time period and the second time period partially overlap; (c) The first time period and the second time period do not overlap at all.

3. The method for preparing a thin film according to claim 2, wherein The first time period is 0.5 to 180 min; and / or, The electric field strength in the electric field treatment is 1x10 4 ~1x10 8 V / m; and / or, The ultrasonic frequency of the first ultrasonic treatment is 20 to 200 KHz; and / or, The temperature of the first ultrasonic treatment is 25 to 100 °C.

4. The method for preparing a thin film according to claim 2, characterized in that, Before the step of providing the saturated solution, there is also a step: Providing an initial saturated solution, the initial saturated solution comprising nanoparticles, and the nanoparticles being connected with ligands; Performing a second energy treatment on the initial saturated solution to obtain a saturated solution comprising the charged nanoparticles.

5. The method for preparing a thin film according to claim 4, wherein The energy of the second energy treatment is greater than the energy of the first energy treatment; and / or, The second energy treatment includes a second ultrasonic treatment, and the power density of the first ultrasonic treatment is less than the power density of the second ultrasonic treatment; and / or, The power density of the second ultrasonic treatment is 0.2 to 10 W / cm 2 ; and / or, The ultrasonic frequency of the second ultrasonic treatment is 20 to 200 KHz; and / or, The temperature of the second ultrasonic treatment is 25 to 100 °C; and / or, The time of the second ultrasonic treatment is 1 to 300 min.

6. The method for preparing a thin film according to claim 4, wherein, Before the step of performing the second energy treatment on the initial saturated solution, there is also: Adding a buffer to the initial saturated solution.

7. The method for preparing the thin film according to claim 6, characterized in that, The buffer includes at least one of tris(hydroxymethyl)aminomethane hydrochloride, phosphate, HEPES, carbonate, acetate, citrate, TAE, TBE, morpholineethanesulfonic acid, 3-morpholinopropanesulfonic acid, glycine, HEPES-KOH, N,N-bis(2-hydroxyethyl)glycine, 3-(cyclohexylamino)-1-propanesulfonic acid, SDS-PAGE, carbamide, formate, propionate, butyrate, lactate; and / or, The concentration of the buffer in the initial saturated solution is 0.0001 to 1 mmol / L.

8. The method for preparing a thin film according to any one of claims 1 to 7, characterized in that, The nanoparticles include at least one of a metal oxide material connected with a first ligand and a quantum dot material connected with a second ligand; and / or, The metal oxide material includes at least one of doped or undoped molybdenum oxide, tungsten oxide, nickel oxide, copper oxide, zinc oxide, barium oxide, aluminum oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, manganese oxide, rhenium oxide, indium oxide, hafnium oxide, and niobium oxide, and the doped element includes at least one of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, gadolinium, tin, europium, erbium, thulium, gallium, and titanium; and / or, The average particle size of the metal oxide material is 1 to 200 nm; and / or, The quantum dot material includes at least one of single-structure quantum dots and core-shell structure quantum dots. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots are each independently selected from at least one of II-VI group compounds, IV-VI group compounds, III-V group compounds, I-III-VI group compounds, perovskite nanoparticle materials, and carbon quantum dots. Among them, the core-shell structure quantum dots include one or more layers. Among them, the II-VI group compounds are selected from at least one of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds are selected from at least one of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; the III-V group compounds are selected from at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, or InAlPSb; the I-III-VI group compounds are selected from at least one of CuInS2, CuInSe2, and AgInS2; the perovskite nanoparticle materials are at least one of inorganic perovskite quantum dots, organic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots. Among them, the structural general formula of the inorganic perovskite quantum dots is AMX3, where A is Cs + ions, M is a divalent metal cation, and M is selected from Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ and Eu 2+ and one or more of the following, X is a halogen anion; the structural general formula of the organic perovskite quantum dot is CMY3, C is formamidinium, and Y is a halogen anion; the structural general formula of the organic-inorganic hybrid perovskite quantum dot is BMZ3, B is selected from organic amine cations, and Z is a halogen anion.

9. The method for preparing the thin film according to claim 8, characterized in that, The first ligand includes at least one of a first carboxylic acid ligand, a sulfonic acid ligand, a first phosphate ligand, a first thiol ligand, an amine-containing ligand, a phosphorus-containing ligand, a betaine ligand, an acetylacetone ligand, a fluoroborate, a fluorophosphate, and a halogen; the second ligand includes at least one of a second carboxylic acid ligand, a second phosphate ligand, and a second thiol ligand; wherein: The first carboxylic acid ligand and the second carboxylic acid ligand independently include at least one of oleic acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, potassium hydrogen phthalate, salicylic acid, o-phenanthroline, tetraacetic acid, boric acid, citric acid, succinic acid, malonic acid, succinic acid, adipic acid, and sodium hydrogen oxalate; and / or, The sulfonic acid ligand includes at least one of benzenesulfonic acid, methanesulfonic acid, ethylsulfonic acid, aminosulfonic acid, methoxybenzenesulfonic acid, nitrobenzenesulfonic acid, hydroxybenzenesulfonic acid, aminobenzenesulfonic acid, 2-aminopyridine-5-sulfonic acid, 2-pyridinesulfonic acid, aminoethanesulfonic acid, aminomethanesulfonic acid, etc.; and / or, The first phosphate ligand and the second phosphate ligand independently include at least one of phosphorus trichloride, phosphorus pentachloride, triphenylphosphine, tri-tert-butylphosphine, tripropylphosphine, triethylphosphine, tributylphosphine, ferrocenephosphine, triphosphine ligand, diethylferrocenephosphine, dibutylferrocenephosphine, diphenylferrocenephosphine, diphenylphosphoric acid, dimethyldiphenylphosphoric acid, diethyldiphenylphosphoric acid, and dipropyldiphenylphosphoric acid; and / or, The first thiol ligand and the second thiol ligand independently include at least one of n-octyl mercaptan, 1-octadecanethiol, 1-dodecyl mercaptan, methyl mercaptan, ethyl mercaptan, propyl mercaptan, butyl mercaptan, methyl benzene mercaptan, and p-methoxy benzene mercaptan; and / or, The amine-containing ligand includes at least one of ethylamine, diethylamine, triethylamine, tetraethylamine, p-toluidine and p-aminoaniline; and / or, The phosphorus-containing ligands include at least one of phosphorus trichloride, phosphorus pentachloride, diethyl phosphate, dimethyl phosphate, etc., phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, triphenylphosphonate, triphenylphosphonium ammonium, phosphatidic acid, dipalmitoylphosphatidic acid, sphingosine, sphingosine, etc., 1-octadecyl-2-hydroxy-3-propylphosphocholine, 1-octadecyl-2-hydroxy-3-propylphosphocholine ammonium salt, polyethylene glycol-phosphatidylethanolamine, polyethylene glycol-phosphatidylcholine; and / or, The betaine ligands include at least one of N-methyl-D-mannitol-1,2-propanediol betaine, N-ethyl-D-mannitol-1,2-propanediol betaine, N,N-dimethyl-N-hexadecylammonium chloride, and N,N-dimethyl-N-eicosylammonium chloride.

10. The method for preparing a thin film according to any one of claims 1 to 7, characterized in that, The steps of applying an electric field treatment and a first energy treatment to the saturated solution include: Applying an electric field treatment and a first energy treatment to the saturated solution, and adding an acidic material to the saturated solution.

11. The method for preparing the thin film according to claim 10, wherein The acidic material includes at least one of HCl, H2SO4, HClO4, HNO3, HClO3, HClO2, HClO, LiClO4, NaClO4, and KClO4; and / or, The concentration of the acidic material in the saturated solution is 0.0001 to 0.1 mmol / L.

12. A film, characterized in that, Prepared by using the method for preparing a thin film according to any one of claims 1 to 11.

13. An optoelectronic device, characterized in that, Including: A first electrode and a second electrode disposed opposite to each other; A functional layer disposed between the first electrode and the second electrode; Wherein, the functional layer includes at least one functional sub-layer, and at least one of the functional sub-layers includes a thin film prepared by using the method for preparing a thin film according to any one of claims 1 to 11, or a thin film according to claim 12.

14. The optoelectronic device according to claim 13, characterized in that, At least one of the functional sub-layers includes a quantum dot light-emitting layer, a hole functional layer, or an electron functional layer; When the hole functional layer is not the thin film, the material of the hole transport layer and / or the hole injection layer includes at least one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal stannides, doped graphene, undoped graphene, and C60; When the electron functional layer is not the thin film, the materials of the electron transport layer and the electron injection layer independently include an inorganic material and / or an organic material; the inorganic material includes one or more of doped or undoped zinc oxide, barium oxide, aluminum oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanate oxide, aluminum zinc oxide, manganese zinc oxide, tin zinc oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc stannide, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate; the doped elements include at least one of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; the organic material includes at least one of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds, polythiophene compounds, perylene diimide compounds, and fullerene compounds.

15. A display device, characterized in that, Including the optoelectronic device according to claim 13 or 14.

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