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

Abstract

The invention discloses a thin film, a preparation method and a preparation device thereof, a photoelectric device and a display device, and relates to the technical field of display. The preparation method comprises the following steps: providing charged semiconductor particles; a first electric field is provided, the charged semiconductor particles enter the first electric field at a first speed V1, the direction of the first speed V1 intersects the direction of the first electric field, and the charged semiconductor particles passing through the first electric field are deposited to form a thin film. The preparation method can improve selective deposition of the charged semiconductor particles, so that the stability, integrity and thickness uniformity of the film are improved, and the film is promoted to exert excellent performance.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to a thin film, a preparation method thereof, a preparation apparatus, an optoelectronic device, and a display device. Background Art

[0002] Currently, the widely used optoelectronic devices are organic light-emitting diodes (OLEDs) and quantum dot light-emitting diodes (QLEDs). Due to its excellent display performance such as self-luminescence, simple structure, ultra-thin and light, fast response speed, wide viewing angle, low power consumption, and flexible display, OLED has become the mainstream technology in the field of display technologies. QLED has the advantages of saturated emission light color and adjustable wavelength, and high photoluminescence and electroluminescence quantum yields, and has become a strong competitor of OLEDs in recent years.

[0003] The structures of traditional OLED and QLED devices generally include an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode. Under the action of an electric field, the holes generated by the anode of the light-emitting diode and the electrons generated by the cathode move, and are respectively injected into the hole transport layer and the electron transport layer, and finally migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated, which excite the light-emitting molecules to finally generate visible light.

[0004] Currently, the thickness of the light-emitting layer thin film is uneven, and its stability and repeatability are poor, and the processing time is long, resulting in low luminous efficiency of the optoelectronic device. Summary of the Invention

[0005] In view of this, this application provides a thin film, a preparation method thereof, a preparation apparatus, an optoelectronic device, and a display device.

[0006] The embodiment of this application is implemented as follows. A preparation method of a thin film includes:

[0007] Providing charged semiconductor particles;

[0008] Providing a first electric field, so that the charged semiconductor particles enter the first electric field at a first speed V 1 The direction of the first speed V 1 intersects with the direction of the first electric field, and the charged semiconductor particles passing through the first electric field are deposited to form a thin film.

[0009] Correspondingly, the embodiment of this application further provides a preparation apparatus of a thin film, including a charging unit, a turning unit, and a substrate arranged in sequence;

[0010] The charging unit includes a third electric field for charging the charged semiconductor particles;

[0011] The turning unit includes a first electric field for turning and depositing the charged semiconductor particles;

[0012] The substrate is used to receive the charged semiconductor particles.

[0013] Accordingly, an embodiment of the present application further provides a thin film, which is prepared by the above preparation method or by the above preparation device.

[0014] Accordingly, an embodiment of the present application further provides an optoelectronic device, including a first electrode, a functional layer, and a second electrode stacked, and the functional layer is prepared by the above preparation method.

[0015] Accordingly, an embodiment of the present application further provides a display device, and the display device includes the above optoelectronic device.

[0016] The preparation method of the thin film described in the present application can improve the selective deposition of charged semiconductor particles, thereby improving the stability, integrity, and thickness uniformity of the thin film, and promoting the thin film to exhibit excellent performance. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 is a flowchart of the preparation method of the thin film provided by the embodiment of the present application;

[0019] Figure 2 is a schematic structural diagram of the preparation device of the thin film provided by the embodiment of the present application;

[0020] Figure 3 is a schematic diagram of the movement trajectory of charged semiconductor particles in the turning unit provided by the embodiment of the present application;

[0021] Figure 4 is a schematic structural diagram of the optoelectronic device provided by the embodiment of the present application;

[0022] Figure 5 is a schematic structural diagram of another optoelectronic device provided by the embodiment of the present application;

[0023] Figure 6 is a front view of the AFM of the thin film provided by Embodiment 1 of the present application;

[0024] Figure 7 is a side view of the AFM of the thin film provided by Embodiment 1 of the present application;

[0025] Figure 8It is the AFM front view of the thin film provided in Comparative Example 1 of the present application;

[0026] Figure 9 It is the AFM side view of the thin film provided in Comparative Example 1 of the present application;

[0027] Figure 10 It is the topography diagram of the thin film provided in Example 1 of the present application;

[0028] Figure 11 It is the topography diagram of the thin film provided in Comparative Example 1 of the present application.

[0029] Reference numerals:

[0030] Charging unit 10; acceleration unit 20; steering unit 30; substrate 40; charged semiconductor particles 50;

[0031] First electrode 100; first carrier functional layer 200; hole injection layer 201; hole transport layer 202; light-emitting layer 300; second carrier functional layer 400; electron transport layer 401; electron injection layer 402; second electrode 500. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation manners described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0033] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" usually refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the drawings; and "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0034] In the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural.

[0035] In this application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "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 both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can each be single or multiple.

[0036] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the description of the range has specifically disclosed all possible sub - ranges and individual values within that range. For example, it should be considered that the description of the range from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0037] The technical solution of this application is as follows:

[0038] In a first aspect, please refer to Figure 1 , an embodiment of this application provides a method for preparing a thin film, including:

[0039] S11. Provide charged semiconductor particles;

[0040] S12. Provide a first electric field to cause the charged semiconductor particles to enter the first electric field at a first velocity V 1 , the direction of the first velocity V 1 intersects with the direction of the first electric field, and the charged semiconductor particles passing through the first electric field are deposited to form a thin film.

[0041] In some embodiments, the charged semiconductor particles land on the substrate 40 and are deposited to form a thin film.

[0042] It should also be noted that the substrate 40 is arranged on the side of the force direction of the charged semiconductor particles. That is to say, when the charged semiconductor particles are positively charged, the substrate is arranged on the negative electrode side of the electric field, and when the charged semiconductor particles are negatively charged, the substrate is arranged on the positive electrode side of the electric field, so that the charged semiconductor particles fall onto the substrate 40.

[0043] The preparation method of the thin film described in this application controls the intersection of the initial velocity and the force direction (the first electric field direction) of charged semiconductor particles, causing the charged semiconductor particles to move under the action of the first electric field. A substrate with a corresponding width is set according to the deflection distance, so that the charged semiconductor particles meeting the particle size requirements fall onto the substrate 40 on the force direction side, thereby reducing the particle size range difference of the charged semiconductor particles in the thin film, improving the selective deposition of the charged semiconductor particles, and further improving the stability, integrity, and thickness uniformity of the thin film, promoting the thin film to exhibit excellent performance.

[0044] It should be noted that when the charged semiconductor particles meeting the particle size requirements fall onto the substrate, the charged semiconductor particles with the same particle size fall one by one to the same position, and the charged semiconductor particles will be superimposed. Generally, the surface of the charged semiconductor particles is smooth, and due to gravity, the charged semiconductor particles will slide to the blank position to fill the groove structure; and the substrate 40 can move, and the substrate 40 can be translated according to the needs of the thin film size to prepare the thin film. In some embodiments, the charge amount of the charged semiconductor particles is positively correlated with the particle size of the charged semiconductor particles.

[0045] It can be understood that the charged semiconductor particles carry positive charges or negative charges, and the charge amount of the charged semiconductor particles is positively correlated with the particle size of the charged semiconductor particles. That is, the larger the particle size of the charged semiconductor particles described in this application, the more charge they carry.

[0046] In some embodiments, the direction of the first velocity V 1 is perpendicular to the direction of the first electric field.

[0047] It can be understood that by controlling the perpendicularity of the initial velocity and the force direction (the first electric field direction) of the charged semiconductor particles, the charged semiconductor particles perform a kind of projectile-like motion under the action of the first electric field. The charge amount of the charged semiconductor particles is positively correlated with the particle size of the charged semiconductor particles. The charged semiconductor particles with the same particle size have the same charge amount and the same deflection distance in the first electric field, so that the charged semiconductor particles meeting the particle size requirements fall onto the substrate 40 on the force direction side, realizing the selective deposition of the charged semiconductor particles.

[0048] In some embodiments, the charged semiconductor particles before entering the first electric field include charged semiconductor particles of M particle sizes, and the particle size range difference of the charged semiconductor particles of the M particle sizes is R 1 ; the charged semiconductor particles falling onto the substrate include charged semiconductor particles of N particle sizes, and the particle size range difference of the charged semiconductor particles of the N particle sizes is R 2 ; where M > N ≥ 1, R 1 > R 2 .

[0049] It can be understood that a substrate 40 with a corresponding width is set according to the deflection distance, so that N types of charged semiconductor particles with particle sizes meeting the requirements fall onto the substrate 40 on the force-receiving direction side, thereby reducing the particle size range difference of the charged semiconductor particles in the thin film.

[0050] In the S11:

[0051] In some embodiments, the charge amount of the charged semiconductor particle is q, the particle size of the charged semiconductor particle is d, and q and d satisfy the following relational expression: q = k·(d / D) 3 ; where k is 500 to 1000, D is the electron cloud diameter of the charged semiconductor particle, and D is 2 nm to 10 nm.

[0052] In some embodiments, the average particle size of the charged semiconductor particles is 2 nm to 20 nm, for example, it can be 3 nm to 18 nm, 4 nm to 16 nm, 5 nm to 15 nm, 6 nm to 12 nm, 8 nm to 10 nm, etc.

[0053] In some embodiments, the charge amount of the charged semiconductor particle is 0.1e to 20e, for example, it can be 1e to 18e, 2e to 15e, 5e to 12e, 8e to 11e, 9e to 10e, etc.

[0054] In some embodiments, the R 1 ranges from 8 to 17, for example, it can be 9 to 16, 10 to 15, 11 to 14, 12 to 13, etc.

[0055] In some embodiments, the R 2 ranges from 2 to 4.

[0056] In some embodiments, the preparation method of the charged semiconductor particles includes:

[0057] S111. Provide a semiconductor particle dispersion liquid, where the semiconductor particle dispersion liquid includes a first solvent, semiconductor particles, and ligands bound to the surfaces of the semiconductor particles;

[0058] S112. Provide a polar solvent, mix the semiconductor particle dispersion liquid and the polar solvent, and place them in a second electric field to obtain charged semiconductor particles.

[0059] In the S111:

[0060] In some embodiments, the semiconductor particles include light-emitting semiconductor particles, P-type semiconductor particles, and N-type semiconductor particles.

[0061] In some embodiments, the light-emitting semiconductor particles include one or more of organic light-emitting materials and quantum dot light-emitting materials.

[0062] The organic light-emitting material includes CBP:Ir(mppy) 3 (4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridine iridium(III)]), TCTX:Ir(mmpy)(4,4',4”-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridine iridium]), a diaryl anthracene derivative, a stilbene aromatic derivative, a pyrene derivative, a fluorene derivative, a TBPe fluorescent material, a TTPX fluorescent material, a TBRb fluorescent material, a DBP fluorescent material, a delayed fluorescence material, a TTA material, a TADF (thermally activated delayed) material, a polymer containing a B-N covalent bond, an HLCT (hybrid local charge transfer excited state) material, an Exciplex (excited complex) light-emitting material, or one or more of these.

[0063] The quantum dot light-emitting material includes one or more of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite semiconductor material.

[0064] 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 can be respectively selected from, but not limited to, the single-structure quantum dots being selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The shell of the core-shell structure quantum dots is one or more layers. The II-VI group compounds include one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, 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 include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The III-V group compounds include one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb. The I-III-VI group compounds include CuInS 2 , CuInSe 2 , and AgInS 2 , one or more of them.

[0065] As an example, the quantum dots of the core-shell structure include one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS.

[0066] The perovskite semiconductor material includes a doped or undoped inorganic perovskite semiconductor or an organic-inorganic hybrid perovskite semiconductor. The general structural formula of the inorganic perovskite semiconductor is AMX 3 , where A is a Cs + ion, M is a divalent metal cation selected from Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ and one or more of them, and X is a halogen anion selected from Cl - , Br - , I - and one or more of them. The general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX 3 , where B is an organic amine cation selected from CH 3 (CH 2 ) n-2 NH 3 + or

[0067] [NH 3 (CH 2 ) n NH 3 2+ , where n≥2, M is a divalent metal cation selected from Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ ​one or more of, X is a halogen anion, selected from Cl - , Br - , I - one or more of.

[0068] In some embodiments, the p-type semiconductor particles include 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent material, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexoxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS doped with s-MoO 3 derivatives of, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine, spiro-NPB, nanocrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfides, metal selenides and metal nitrides, one or more of, the metal oxides in the second doped metal oxide particles and the metal oxides in the second undoped metal oxide particles each independently include MoO 3 , WO 3 , NiO, CrO 3 , CuO, V2 O 5 One or more of the following, the doping elements in the second doped metal oxide particles include one or more of Mo, W, Ni, Cr, Cu, V, and the metal sulfide includes CuS, MoS 3 , WS 3 One or more of the following, the metal selenide includes MoSe 3 , WSe 3 One or more of the following, and the metal nitride includes p-type gallium nitride.

[0069] In some embodiments, the N-type semiconductor particles include one or more of first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The material of the first undoped metal oxide particles includes one or more of ZnO, TiO 2 , SnO 2 , ZrO 2 , Ta 2 O 5 One or more of the following, the metal oxides in the first doped metal oxide particles include ZnO, TiO 2 , SnO 2 , ZrO 2 , Ta 2 O 5 , Al 2 O 3 One or more of the following, the doping elements in the first doped metal oxide particles include one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga. The IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, CdS. The IIIA-VA group semiconductor materials include one or more of InP, GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS, CuGaS.

[0070] In some embodiments, the average particle size of the semiconductor particles is 2 nm to 20 nm, for example, it can be 3 nm to 18 nm, 4 nm to 16 nm, 5 nm to 15 nm, 6 nm to 12 nm, 8 nm to 10 nm, etc.

[0071] Further, the average particle size of the p-type semiconductor particles and the N-type semiconductor particles is 2 nm to 10 nm, for example, it can be 3 nm to 9 nm, 4 nm to 8 nm, 5 nm to 7 nm, etc.

[0072] The average particle size of the luminescent semiconductor particles is 4 nm to 20 nm, for example, it can be 5 nm to 19 nm, 6 nm to 18 nm, 7 nm to 15 nm, 8 nm to 12 nm, 9 nm to 10 nm, etc.

[0073] In some embodiments, the ligand includes one or more of propylene glycol derivatives, thiol compounds, thiocarboxylic acid compounds, ester group compounds, cysteine, glutamic acid, formaldehyde, acetone, dodecylamine, hexadecylamine, triacetyl phosphate, hexaacetyl triphosphate, ethanolamine, and mercaptoethanol.

[0074] In some embodiments, the molar ratio of the semiconductor particles to the ligand is 1:(1 to 5), for example, it can be 1:(1.5 to 4.5), 1:(1.6 to 4), 1:(1.8 to 3.5), 1:(2 to 3), 1:(2.2 to 2.8), etc. Within the range of the molar ratio, it is beneficial to improve the compatibility of the semiconductor particles with the first solvent, enable the semiconductor particles to be stably dispersed in the first solvent, and can also prevent the semiconductor particles from aggregating.

[0075] In some embodiments, the first solvent includes one or more of water, alcohol compounds, ether compounds, and ester compounds. The first solvent has polarity.

[0076] Furthermore, the alcohol compounds include one or more of trimethoxybutanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, and cresol.

[0077] The ether compounds include one or more of diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethylene oxide, and tetrahydrofuran.

[0078] The ester compounds include one or more of ethyl acetate, propylene glycol methyl ether acetate, ethyl benzoate, isopropyl benzoate, dioctyl phthalate, butyl levulinate, dibutyl hexanoate, and isooctyl butyrate. In some embodiments, in the semiconductor particle dispersion liquid, the mass fraction of the semiconductor particles is 5% to 20%, for example, it can be 6% to 18%, 8% to 16%, 9% to 15%, 10% to 14%, 12% to 13%, etc. Within the range of the mass fraction, it is beneficial for the semiconductor particles to be uniformly dispersed in the first solvent.

[0079] In the S112:

[0080] In some embodiments, the polar solvent includes one or more of water, alcohol compounds, ether compounds, and ester compounds.

[0081] Specifically, the alcohol compounds include one or more of trimethoxybutanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, and cresol.

[0082] The ether compounds include one or more of diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethylene oxide, and tetrahydrofuran.

[0083] The ester compounds include one or more of ethyl acetate, propylene glycol methyl ether acetate, ethyl benzoate, isopropyl benzoate, dioctyl phthalate, butyl levulinate, dibutyl hexanoate, and isooctyl butyrate.

[0084] It should be noted that the polar solvent has polarity, and the polarity of the polar solvent is greater than that of the first solvent.

[0085] In some embodiments, the volume ratio of the semiconductor particle dispersion to the polar solvent is 1:(1 - 30), for example, it can be 1:(2 - 28), 1:(5 - 25), 1:(10 - 22), 1:(12 - 20), 1:(15 - 18), etc. Within the range of the volume ratio, it is beneficial for the polar solvent to modify the semiconductor particles. The polar groups in the polar solvent can induce the semiconductor particles to ionize and generate charges, thereby increasing the charge amount of the semiconductor particles and making the semiconductor particles electrically charged.

[0086] In some embodiments, the mixing time of the semiconductor particle dispersion and the polar solvent is 10 min - 30 min, for example, it can be 12 min - 28 min, 15 min - 27 min, 16 min - 26 min, 18 min - 25 min, 20 min - 22 min, etc.; the mixing temperature is 25°C - 50°C, for example, it can be 26°C - 48°C, 28°C - 45°C, 30°C - 42°C, 32°C - 40°C, 35°C - 38°C, etc. In this way, it is beneficial for the polar solvent to fully modify the semiconductor particles and improve the charge amount of the semiconductor particles.

[0087] In some embodiments, after the semiconductor particle dispersion and the polar solvent are mixed, it further includes standing for 5 - 30 min, for example, it can be 6 - 28 min, 8 - 25 min, 10 - 22 min, 12 - 20 min, 15 - 18 min, etc.

[0088] It should be noted that when the semiconductor particle dispersion liquid is mixed with the polar solvent, the functional groups on the ligands on the surface of the semiconductor particles can interact with the polar molecules in the polar solvent. The interactions mainly include: the hydrogen atoms on the functional groups form hydrogen bonds with atoms such as oxygen and nitrogen in the polar solvent; and there will be electrostatic interactions between the polar molecules in the polar solvent and the charged atoms on the functional groups; there will also be van der Waals forces between the polar molecules and the functional groups. These interactions act together to change the electronic structure of the semiconductor particles, causing the semiconductor particles to form an electrochemical interface with uneven charge distribution. The charge distribution on this interface can change with the chemical properties and concentration of the polar solvent, and the semiconductor particles will exhibit complex charge states, including positive charges, negative charges, and neutral charges at the same time.

[0089] In some embodiments, the voltage of the second electric field is 1V to 10V, for example, it can be 2V to 9V, 3V to 8V, 4V to 7V, 5V to 6V, etc. Within the above voltage range, it is beneficial to make the semiconductor particles have a single charge.

[0090] It should be noted that among the charged semiconductor particles prepared in the same batch, the ligands on the surface of the semiconductor particles are the same. That is to say, the density and type of the functional groups of the surface ligands are the same. When the functional group density is equal, the larger the surface area of the semiconductor particles, the more functional groups it has. And the type and density of the polar solvent are consistent. The larger the particle size of the semiconductor particles, the more functional groups it has, and the more hydrogen bonds, electrostatic interactions, and van der Waals forces there are between it and the polar solvent, that is, the more interactions there are between the semiconductor particles with larger particle size and the polar solvent. The voltage of the second electric field is fixed. The more interactions there are between the conductor particles and the polar solvent, the more charges are generated by the ionization of the semiconductor particles under the action of the fixed voltage of the second electric field and the polar solvent. Therefore, the charge amount on the surface of the semiconductor particles is positively correlated with the particle size of the semiconductor particles, that is, the larger the particle size of the semiconductor particles, the more charge amount.

[0091] In some embodiments, the method of placing in the second electric field includes: injecting into the second electric field at a second speed V 2

[0092] In some embodiments, the second speed V 2 is 1 cm / s to 10 cm / s, for example, it can be 2 cm / s to 9 cm / s, 3 cm / s to 8 cm / s, 4 cm / s to 7 cm / s, 5 cm / s to 6 cm / s, etc. In some embodiments, the direction of the second speed V 2 intersects with the direction of the second electric field. Further, the direction of the second speed V 2 can be perpendicular to the direction of the second electric field. In other embodiments, the second speed V​2 The direction of the [object] can also be parallel to the direction of the second electric field.

[0093] It can be understood that since the polar solvent contains polar groups, the polar groups and the second electric field can induce the ionization of semiconductor particles to generate charges, increase the charge amount of the semiconductor particles, and make the semiconductor particles exhibit the characteristics of a single charge, that is, they have an electric property.

[0094] It should be noted that when the charged semiconductor particles and the polar solvent are placed in an electric field, the charged semiconductor particles move under the action of the electric field, while the polar solvent does not carry charges and remains in place, or when the polar solvent enters the electric field at a certain flow rate, it decelerates until the flow rate drops to 0.

[0095] In the S12:

[0096] In some embodiments, before the charged semiconductor particles enter the first electric field, it further includes making the charged semiconductor particles enter the third electric field at a second speed V 2 The direction of the second speed V 2 is parallel to the direction of the third electric field.

[0097] In some embodiments, the voltage of the third electric field is 20V to 30V, for example, it can be 21V to 29V, 22V to 28V, 23V to 27V, 24V to 26V, etc. Within the above voltage range, it is beneficial to accelerate the charged semiconductor particles to the first speed V 1 .

[0098] In some embodiments, the first speed V 1 is 1 cm / s to 10 cm / s, for example, it can be 2 cm / s to 9 cm / s, 3 cm / s to 8 cm / s, 4 cm / s to 7 cm / s, 5 cm / s to 6 cm / s, etc.

[0099] In some embodiments, the voltage of the first electric field is 10V to 20V, for example, it can be 11V to 19V, 12V to 18V, 13V to 17V, 14V to 16V, etc.

[0100] In some embodiments, the substrate has pixel openings arranged in an array.

[0101] Furthermore, the length of the pixel opening is 100 μm to 200 μm, the width is 500 μm to 800 μm, and the depth is 200 nm to 300 nm. It should be noted that the width is in the direction parallel to the positive and negative substrates at both ends of the first electric field.

[0102] It can be understood that the pixel opening has a groove structure, the length and width of which can be set by itself, and the groove width gradually expands along the direction of the groove opening. When quantum dots meeting the particle size requirements fall into the pixel pit, due to gravity, they will slide along the groove wall of the groove to the bottom of the groove, so that the charged quantum dots fill the pixel opening.

[0103] In some embodiments, the substrate 40 is disposed in the first electric field. In other embodiments, the substrate 40 may also be disposed outside the first electric field.

[0104] In some embodiments, the thickness of the thin film is 40 nm to 60 nm, for example, it can be 41 nm to 59 nm, 42 nm to 58 nm, 44 nm to 56 nm, 45 nm to 55 nm, 48 nm to 50 nm, etc.

[0105] In a second aspect, an embodiment of the present application further provides a thin film prepared by the above preparation method.

[0106] In a third aspect, please refer to Figure 2 , an embodiment of the present application further provides a preparation device for a thin film, which is applied to the above preparation method of the thin film. The preparation device includes a charging unit 10, a turning unit 30, and a substrate 40 arranged in sequence. The charging unit 10 includes a third electric field for charging charged semiconductor particles; the turning unit 30 includes a first electric field for turning and depositing the charged semiconductor particles; the substrate 40 is used to receive the charged semiconductor particles.

[0107] In some embodiments, the preparation device further includes an injection unit, and the injection unit is disposed adjacent to the charging unit 10 for injecting the charged semiconductor particles into the charging unit 10.

[0108] In some embodiments, the injection unit includes one or several of an injection pump and a stamping pump.

[0109] In some embodiments, the preparation device further includes an acceleration unit 20, and the acceleration unit 20 is disposed between the charging unit 10 and the turning unit 30; the acceleration unit 20 includes a second electric field, and the direction of the second electric field intersects with the direction of the first electric field.

[0110] Furthermore, the direction of the second electric field is perpendicular to the direction of the first electric field.

[0111] In some embodiments, the acceleration unit 20 includes a first metal plate and a second metal plate that are oppositely arranged. The first metal plate and the second metal plate define the second electric field. The first metal plate is provided with a first notch for communicating the charging unit 10 and the acceleration unit 20, and the second metal plate is provided with a second notch for communicating the charging unit 10 and the steering unit 30.

[0112] In some embodiments, the width of the first notch is 0.2 μm to 0.5 μm, and can be, for example, 0.25 μm to 0.45 μm, 0.3 μm to 0.4 μm, 0.32 μm to 0.35 μm, etc.

[0113] In some embodiments, the width of the second notch is 0.2 μm to 0.5 μm, and can be, for example, 0.25 μm to 0.45 μm, 0.3 μm to 0.4 μm, 0.32 μm to 0.35 μm, etc.

[0114] In some embodiments, the preparation device further includes a moving unit for moving the substrate.

[0115] Further, the moving unit can be a stepper. It can be understood that the substrate has pixel openings, and the moving unit can move the substrate so that the charged semiconductor particles fill the pixel openings.

[0116] In some embodiments, the steering unit 30 includes a third metal plate and a fourth metal plate that are oppositely and parallelly arranged. The first electric field is defined between the third metal plate and the fourth metal plate. Further, the ratio of the length of the third metal plate and the fourth metal plate to the distance between the third metal plate and the fourth metal plate is (10 - 15):1, and can be, for example, (10.5 - 14.5):1, (11 - 14):1, (11.5 - 13.5):1, (12 - 13):1, etc.

[0117] Specifically, in some embodiments, the length of the third metal plate and the fourth metal plate is 100 cm to 300 cm, and can be, for example, 120 cm to 280 cm, 150 cm to 260 cm, 160 cm to 250 cm, 180 cm to 240 cm, 200 cm to 220 cm, etc.

[0118] In some embodiments, the distance between the third metal plate and the fourth metal plate is 10 cm to 20 cm, and can be, for example, 11 cm to 19 cm, 12 cm to 18 cm, 13 cm to 17 cm, 14 cm to 16 cm, etc.

[0119] In some embodiments, the extending direction of the substrate 40 is perpendicular to the direction of the first electric field.

[0120] In some embodiments, the steering unit 30 further includes a magnetic field, and the magnetic field and the first electric field form an electromagnetic field.

[0121] In some embodiments, the direction of the magnetic field is parallel to the direction of the first electric field.

[0122] In some embodiments, the intensity of the magnetic field is 500 G to 1000 G, for example, it can be 520 G to 950 G, 550 G to 900 G, 600 G to 850 G, 650 G to 800 G, 700 G to 750 G, etc. Within the intensity range of the magnetic field, it is beneficial for the semiconductor particles to be smoothly deposited from the steering unit 30 onto the substrate 40, and reduce the loss of semiconductor particles within the steering unit 30.

[0123] When preparing a thin film using the thin film preparation apparatus provided in the present application, after mixing the semiconductor particle dispersion liquid and the polar solvent, it is injected into the charging unit 10 at a speed of V 2 , and after passing through the charging unit 10, it carries a single charge, passes through the first notch, and enters the third electric field in a direction perpendicular to the third electric field. Under the action of the third electric field, it is accelerated to V 1 , and then enters the steering unit 30 in a direction perpendicular to the first electric field. Due to the uneven size of the semiconductor particles, the offset distances of semiconductor particles with different particle sizes when leaving the steering unit 30 are different, and semiconductor particles with the same particle size fall to the same position on the substrate 40, thereby improving the selective deposition of semiconductor particles with the same particle size.

[0124] Specifically, please refer to Figure 3 , the mass of the charged semiconductor particle is m, the charge amount is q, when the charged semiconductor particle passes through the third electric field in the acceleration unit 20, the speed when entering the third electric field is V 3 , the speed when leaving the third electric field is V 1 , the voltage of the third electric field is U 3 , then according to the kinetic energy theorem, we can obtain:

[0125] qU 3 =1 / 2mV 1 2 -1 / 2mV 3 2 (Ⅰ)

[0126] Since the velocity direction of the charged semiconductor particle is perpendicular to the direction of the first electric field, the charged semiconductor particle undergoes a projectile-like motion in the first electric field. The voltage of the first electric field is U 1 , the length of the first metal plate and the second metal plate is L, and the distance between the first metal plate and the second metal plate is h. Then the offset amount y of the semiconductor particle in the first electric field is:

[0127] y = 1 / 2at 2 = qUL 2 / 2mv 1 2 h (Ⅱ)

[0128] Combining (Ⅰ) and (Ⅱ) gives:

[0129] y = qU 1 L 2 / (4qU 3 h + 2mV 1 2 h);

[0130] The turning angle tanθ of the charged semiconductor particles in the first electric field is:

[0131] tanθ = U 1 L / 2hU 3 ;

[0132] That is to say, the electric charge of the charged semiconductor particles is positively correlated with its offset in the first electric field and has nothing to do with the turning angle. The larger the charge, the larger the offset.

[0133] In some embodiments, the minimum radius r of the N kinds of charged semiconductor particles with different particle sizes min = (qV / (2πε 0 ))^ 1 / 2 ×(m / 2E)^ 1 / 2 ×(l / h)^ 1 / 2 ×sinθ. The maximum radius r max = [(2 / 3)×(qV / (2πε 0 ))^ 1 / 2 ×(m / 2E)^ 1 / 2 ×(l / h)^ 1 / 2 ×sin(2θ)] + h / 2. Where sinθ = h / 2L, q is the electric charge of the charged semiconductor particles, V is the potential difference of the third electric field, ε 0 is the vacuum permittivity, with a value of 8.854187817×10 -12 F / m, m is the mass of the charged semiconductor particles, E is the electric field strength of the third electric field, l is the depth of the pixel opening, h is the width perpendicular to the electric field direction of the first electric field, L is the length along the electric field direction of the first electric field, and θ is the angle between the tangent of the movement trajectory of the charged semiconductor particles and the direction perpendicular to the electric field direction of the first electric field.

[0134] Fourthly, please refer to Figure 4 and Figure 5, the embodiment of the present application further provides an optoelectronic device, which includes a first electrode 100, a functional layer, and a second electrode 500 arranged in a stacked manner, and the functional layer is prepared by the above-mentioned method for preparing the thin film.

[0135] In some embodiments, the optoelectronic device includes a light-emitting layer 300, and the light-emitting layer 300 is prepared by the above-mentioned method for preparing the thin film.

[0136] In some embodiments, the functional layer includes one or several of a first carrier functional layer 200 and a second carrier functional layer 400. The first carrier functional layer 200 is arranged between the first electrode 100 and the light-emitting layer 300, and the second carrier functional layer 400 is arranged between the light-emitting layer 300 and the second electrode 500. Among them, one or several of the light-emitting layer 300, the first carrier functional layer 200, and the second carrier functional layer 400 are prepared by the above-mentioned method for preparing the thin film.

[0137] It can be understood that in the preparation process of the optoelectronic device, the preparation method of the functional layer can refer to the preparation method of the thin film.

[0138] In some embodiments, the substrate 40 includes a preform of an optoelectronic device. The preform of the optoelectronic device includes a first electrode 100, and the thin film is the first carrier functional layer 200 or the light-emitting layer 300.

[0139] In other embodiments, the substrate 40 includes a preform of an optoelectronic device. The preform of the optoelectronic device includes a first electrode 100 and a first carrier functional layer 200, and the thin film is the light-emitting layer 300.

[0140] In still other embodiments, the substrate 40 includes a preform of an optoelectronic device. The preform of the optoelectronic device includes a first electrode 100 and a light-emitting layer 300, and the thin film is the second carrier functional layer 400.

[0141] In still other embodiments, the substrate 40 includes a preform of an optoelectronic device. The preform of the optoelectronic device includes a first electrode 100, a first carrier functional layer 200, and a light-emitting layer 300, and the thin film is the second carrier functional layer 400.

[0142] In some embodiments, the materials of the first electrode 100 and the second electrode 500 respectively include one or more of metals, carbon materials, and metal oxides; the metals include one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon materials include one or more of graphite, carbon nanotubes, graphene, and carbon fibers; the metal oxides include metal oxide electrodes or composite electrodes with a metal sandwiched between doped or undoped transparent metal oxides, and the materials of the metal oxide electrodes include one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO 3 and one or more of AMO, and the composite electrodes include one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO 2 / Ag / TiO 2 and TiO 2 / Al / TiO 2 One or more of them. Among them, " / " represents a stacked structure. For example, AZO / Ag / AZO represents a composite electrode including a sequentially stacked AZO layer, Ag layer, and AZO layer.

[0143] In some embodiments, the thickness of the first electrode 100 is 100 nm to 200 nm, for example, it can be 110 nm to 190 nm, 120 nm to 180 nm, 130 nm to 170 nm, 140 nm to 160 nm, 150 nm to 155 nm, etc.

[0144] In some embodiments, the thickness of the second electrode 500 is 100 nm to 200 nm, for example, it can be 110 nm to 190 nm, 120 nm to 180 nm, 130 nm to 170 nm, 140 nm to 160 nm, 150 nm to 155 nm, etc.

[0145] In some embodiments, the thickness of the light-emitting layer 300 is 40 nm to 60 nm, for example, it can be 41 nm to 59 nm, 42 nm to 58 nm, 44 nm to 56 nm, 45 nm to 55 nm, 48 nm to 50 nm, etc.

[0146] In some embodiments, the first carrier functional layer 200 is a hole functional layer, and the second carrier functional layer 400 is an electron functional layer.

[0147] In other embodiments, the second carrier functional layer 400 is a hole functional layer, and the first carrier functional layer 200 is an electron functional layer.

[0148] The hole functional layer includes one or more of a hole injection layer 201 and a hole transport layer 202. The electron functional layer includes one or more of an electron injection layer 402 and an electron transport layer 401.

[0149] In some embodiments, the thickness of the first carrier functional layer 200 is 30 nm to 50 nm, for example, it can be 32 nm to 48 nm, 35 nm to 46 nm, 36 nm to 45 nm, 37 nm to 42 nm, 38 nm to 40 nm, etc.

[0150] In some embodiments, the thickness of the second carrier functional layer 400 is 30 nm to 50 nm, for example, it can be 32 nm to 48 nm, 35 nm to 46 nm, 36 nm to 45 nm, 37 nm to 42 nm, 38 nm to 40 nm, etc.

[0151] In a fifth aspect, the present application further relates to a display device, and the display device includes the optoelectronic device.

[0152] The display device can be any electronic product with a display function. The electronic product includes but is not limited to a smart phone, a tablet computer, a notebook computer, a digital camera, a digital video camera, a smart wearable device, a smart weighing electronic scale, a vehicle-mounted display, a television, or an e-book reader. Among them, the smart wearable device can be, for example, a smart bracelet, a smart watch, a virtual reality (VR) helmet, etc.

[0153] The present application will be specifically described below through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0154] Embodiment 1

[0155] This device embodiment provides a thin film, and its preparation method is as follows:

[0156] CdS quantum dots with various particle sizes are provided, and the particle size range is 6 nm to 12 nm. Propylene glycol derivative ligands are bound to their surfaces, and they are dispersed in ethanol to obtain a quantum dot solution. 100 mL of the quantum dot solution is mixed with 100 mL of n-octane, stirred at 40 °C for 10 min and then left to stand for 10 min to obtain an intermediate solution;

[0157] A charging unit, an acceleration unit 20, and a steering unit are provided in sequence. The voltage of the charging unit is 3 V, the voltage of the acceleration unit 20 is 20 V, and the voltage of the steering unit is 10 V. The electric field directions of the charging unit and the steering unit are the same and perpendicular to the electric field direction of the acceleration unit 20. A substrate with a certain width is placed on the right side of the steering unit, close to the side of the force direction of the quantum dots in the intermediate solution, perpendicular to the electric field direction of the steering unit;

[0158] The intermediate solution is injected into the charging unit by means of pump injection at a speed of 5 cm / s, and the direction of the speed is perpendicular to the electric field direction of the charging unit. After passing through the charging unit, the acceleration unit 20, and the steering unit, part of the intermediate solution is deposited on the substrate. The particle size range of the quantum dots in the intermediate solution deposited on the substrate is 8 nm to 10 nm, and a thin film with a thickness of 50 nm is obtained.

[0159] Example 2

[0160] This example is basically the same as Example 1, except that in this example, the CdS quantum dots are replaced with zinc oxide particles.

[0161] Example 3

[0162] This example is basically the same as Example 1, except that in this example, the CdS quantum dots are replaced with PEDOT:PSS particles.

[0163] Example 4

[0164] This example is basically the same as Example 1, except that 100 mL of the quantum dot solution is mixed with 1500 mL of n-octane.

[0165] Example 5

[0166] This example is basically the same as Example 1, except that 100 mL of the quantum dot solution is mixed with 3000 mL of n-octane.

[0167] Example 6

[0168] This example is basically the same as Example 1, except that in this example, n-octane is replaced with diethyl ether.

[0169] Example 7

[0170] This example is basically the same as Example 1, except that in this example, the thickness of the thin film is 40 nm.

[0171] Example 8

[0172] This example is basically the same as Example 1, except that in this example, the thickness of the thin film is 60 nm.

[0173] Comparative Example 1

[0174] This Comparative Example 1 is basically the same as Example 1, except that in this comparative example, an inkjet printing technique is used to print the quantum dot solution on the substrate.

[0175] Comparative Example 2

[0176] This Comparative Example 1 is basically the same as Example 2, except that in this comparative example, an inkjet printing technique is used to print a zinc oxide solution on a substrate.

[0177] Comparative Example 3

[0178] This Comparative Example 1 is basically the same as Example 1, except that in this comparative example, an inkjet printing technique is used to print a PEDOT:PSS solution on a substrate.

[0179] The thin films in Example 1 and Comparative Example 1 were observed using an atomic force microscope. The AFM front view of the thin film in Example 1 is as Figure 6 shown, and the AFM side view of the thin film in Example 1 is as Figure 7 shown. The AFM front view of the thin film in Comparative Example 1 is as Figure 8 shown, and the AFM side view of the thin film in Comparative Example 1 is as Figure 9 shown.

[0180] It can be seen from Figures 6-7 that the thin film prepared by this solution is dense and complete, with uniform thickness and no obvious surface defects; while it can be seen from Figures 8-9 that the thickness of the thin film in Comparative Example 1 is uneven, the thin film is incomplete, there are large voids on the surface, and there are surface defects.

[0181] The uniformity of the thin films in Example 1 and Comparative Example 1 was observed using a profilometer. The topography map of the thin film in Example 1 is as Figure 10 shown, and the topography map of the thin film in Comparative Example 1 is as Figure 11 shown.

[0182] It can be seen from Figures 10-11 that the thickness of the thin film prepared by this solution is concentrated in the range of 45.9 nm to 55.9 nm, and 90.8% of the thickness on the surface of the thin film is within this range, indicating that its thickness is uniform, and its density and stability are good. While for the thin film prepared by the comparative example, only 47% of the surface thickness is concentrated in the range of 42.6 nm to 52.6 nm, and the thickness is significantly uneven, seriously affecting the performance of the thin film.

[0183] Device Example 1

[0184] This device example provides an optoelectronic device, and its preparation method is as follows:

[0185] Provide ITO glass, clean the ITO glass with a cleaning agent to remove the stains on the surface, and then ultrasonically clean the ITO glass with deionized water, isopropyl acetone, acetone and deionized water for 20 minutes in sequence, and then dry it with nitrogen to obtain an ITO anode with a thickness of 30 nm;

[0186] Deposit PEDOT:PSS on the ITO anode, heat it at 150 °C for 30 min to remove moisture, and form a hole injection layer with a thickness of 30 nm;

[0187] Use a pipette to suck 40 μL of the TFB solution, slowly drop it on the modified layer, and perform spin coating at a rotation speed of 4000 rpm for 30 s. Then, perform annealing at an annealing temperature of 150 °C for 30 min to obtain a hole transport layer with a thickness of 30 nm, and obtain a preform of the optoelectronic device;

[0188] The preform of the optoelectronic device is the substrate of Example 1. After forming a quantum dot thin film (light-emitting layer) on the substrate, disperse the ZnO ethanol solution with a concentration of 20 mg / mL on the light-emitting layer, perform spin coating at a rotation speed of 3000 rpm for 30 s, and then perform annealing at an annealing temperature of 80 °C for 30 min to obtain an electron functional layer with a thickness of 40 nm;

[0189] Place the device in an evaporation chamber and thermally evaporate a layer of silver metal through a mask plate to obtain a cathode with a thickness of 100 nm;

[0190] Heat-treat the above device at 120 °C for 15 min and encapsulate it to obtain an optoelectronic device.

[0191] Device Example 2

[0192] This device example is basically the same as Device Example 1, except that in this example, the substrate of Example 1 is replaced with an ITO anode, a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer prepared by spin coating on the hole transport layer. Then, an electron functional layer is formed on the substrate with reference to Example 2.

[0193] Device Example 3

[0194] This device example is basically the same as Device Example 1, except that in this example, the substrate of Example 1 is replaced with an ITO anode, and then a hole transport layer is formed on the substrate with reference to Example 3.

[0195] Device Examples 4-8

[0196] This device example is basically the same as Device Example 1, except that in this example, the preparation method of the light-emitting layer is prepared by the preparation methods of Examples 4-8.

[0197] Device Comparative Example 1

[0198] This device example is basically the same as Device Example 1, except that in this example, the light-emitting layer is prepared by the preparation method of Comparative Example 1.

[0199] Device Comparative Example 2

[0200] This device embodiment is basically the same as Device Embodiment 2, except that the electronic functional layer in this embodiment is prepared by the preparation method of Comparative Example 2.

[0201] Device Comparative Example 3

[0202] This device embodiment is basically the same as Device Embodiment 1, except that the hole functional layer in this embodiment is prepared by the preparation method of Comparative Example 3.

[0203] The optoelectronic devices in Device Embodiments 1-8 and Device Comparative Examples 1-3 were tested for the maximum external quantum efficiency EQE and service life T95@1k nit, and the test results are shown in Table 1.

[0204] Among them, the detection method of the maximum external quantum efficiency is: the ratio of the number of electron-hole pairs injected into the quantum dots to the number of emitted photons, with the unit of %, which is an important parameter to measure the quality of electro-optic devices and can be obtained by measuring with an EQE optical test instrument. The specific calculation formula is as follows:

[0205]

[0206] Among them, ηe is the light output coupling efficiency, ηr is the ratio of the number of recombined carriers to the number of injected carriers, χ is the ratio of the number of excitons generating photons to the total number of excitons, KR is the radiation process rate, and KNR is the non-radiation process rate.

[0207] Test conditions: Conducted at room temperature, with the air humidity of 30-60%.

[0208] The test method for the life T95@1000nit is: the time required for the device to reduce the brightness to a certain proportion of the maximum brightness under constant current or voltage drive. The time when the brightness drops to 95% of the maximum brightness is defined as T95, and this life is the measured life. To shorten the test cycle, the device life test is usually carried out by accelerating the device aging at high brightness, and the life at high brightness is obtained by fitting with an extended exponential decay brightness decay fitting formula. For example, the life at 1000nit is denoted as T95@1000nit. The specific calculation formula is as follows:

[0209]

[0210] Among them, T95L is the life at low brightness, T95H is the measured life at high brightness, LH is the device accelerated to the maximum brightness, LL is 1000nit, A is the acceleration factor, and in this experiment, the A value is obtained as 1.7 by measuring the lives of several groups of green QLED devices at the rated brightness.

[0211] Table 1

[0212]

[0213] As can be seen from Table 1:

[0214] From Device Examples 1 to 3 and Device Comparative Examples 1 to 3, it can be seen that whether preparing the light-emitting layer thin film, the electron functional layer thin film or the hole functional layer thin film by using the solution provided in the present application, compared with the inkjet printing method in Device Comparative Examples 1 to 3, the maximum external quantum efficiency of the optoelectronic device is significantly improved, and the service life is also significantly extended. This is because the functional thin film prepared by this solution is more uniform and dense, thereby improving the stability of the optoelectronic device;

[0215] From Device Example 1, Device Examples 4 to 5 and Device Comparative Example 1, within the ratio range of the semiconductor particle dispersion liquid and the polar solvent provided in the present application, there is no significant difference in the maximum external quantum efficiency and the service life between the optoelectronic devices of Device Example 1 and Device Examples 4 to 5. It can be understood that the polar groups in the polar solvent can react with the functional groups on the surface of the semiconductor particles to induce the ionization of the semiconductor particles to generate charges, which is conducive to selective deposition, obtaining a thin film with high uniformity and density, improving the light-emitting efficiency of the optoelectronic device, and extending the service life of the optoelectronic device;

[0216] From Device Example 1, Device Example 6 and Device Comparative Example 1, replacing the polar solvent to prepare charged semiconductor particles has no significant impact on the maximum external quantum efficiency and the service life of the optoelectronic device, and the performances of the optoelectronic devices of Device Example 1 and Device Example 6 are both superior to those of the optoelectronic device in Device Comparative Example 1;

[0217] From Device Example 1, Device Examples 7 to 8 and Device Comparative Example 1, the maximum external quantum efficiency and the service life of the optoelectronic devices of Device Example 1 and Device Examples 7 to 8 are both superior to those of Device Comparative Example 1. Using the method provided in the present application to prepare thin films with different thicknesses and then applying them to optoelectronic devices has little impact on the performance of the optoelectronic devices.

[0218] The thin film, its preparation method, preparation device, optoelectronic device, and display device provided in the embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A method for preparing a thin film, characterized in that, comprising: providing charged semiconductor particles; Provide a first electric field to cause the charged semiconductor particles to have a first velocity V 1 Enter the first electric field, and the direction of the first velocity V 1 Intersects with the direction of the first electric field, and the charged semiconductor particles passing through the first electric field are deposited to form a thin film.

2. The preparation method according to claim 1, characterized in that, the charge amount of the charged semiconductor particles is positively correlated with the particle size of the charged semiconductor particles; and / or The direction of the first velocity V 1 is perpendicular to the direction of the first electric field; and / or The charged semiconductor particles before entering the first electric field include charged semiconductor particles of M particle sizes, and the particle size range of the charged semiconductor particles of the M particle sizes is R 1 The charged semiconductor particles falling onto the substrate include charged semiconductor particles of N particle sizes, and the particle size range of the charged semiconductor particles of the N particle sizes is R 2 ; where M > N ≥ 1, R 1 > R 2 .

3. The preparation method according to claim 1, characterized in that, The charge of the charged semiconductor particle is q, the particle size of the charged semiconductor particle is d, and q and d satisfy the following relational expression: q = k·(d / D) 3 ; where k is 500 to 1000, D is the electron cloud diameter of the charged semiconductor particle, and D is 2 nm to 10 nm.

4. The preparation method according to claim 2, characterized in that, the average particle size of the charged semiconductor particles is 2 nm to 20 nm; and / or the charge amount of the charged semiconductor particles is 0.1 e to 20 e; and / or The first speed V 1 is 1 cm / s to 10 cm / s; and / or the voltage of the first electric field is 10 V to 20 V; and / or the thickness of the thin film is 40 nm to 60 nm; and / or The said R 1 has a range of 8 to 17; and / or The said R 2 ranges from 2 to 3.

5. The preparation method according to claim 1, characterized in that, the preparation method of the charged semiconductor particles comprises: providing a semiconductor particle dispersion liquid, the semiconductor particle dispersion liquid comprising a first solvent, semiconductor particles, and a ligand bound to the surface of the semiconductor particles; providing a polar solvent, mixing the semiconductor particle dispersion liquid and the polar solvent, and placing them in a second electric field to obtain charged semiconductor particles.

6. The preparation method according to claim 5, characterized in that, the semiconductor particles include luminescent semiconductor particles, P-type semiconductor particles, and N-type semiconductor particles; and / or the ligand includes one or more of propylene glycol derivatives, thio thiol compounds, thio carboxylic acid compounds, ester group compounds, cysteine, glutamic acid, formaldehyde, acetone, dodecylamine, hexadecylamine, triacetyl phosphate, hexaacetyl triphosphate, ethanolamine, and mercaptoethanol; and / or the first solvent includes one or more of water, alcohol compounds, ether compounds, and ester compounds; the alcohol compounds include one or more of trimethoxybutanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, and cresol; the ether compounds include one or more of diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethylene oxide, and tetrahydrofuran; the ester compounds include one or more of ethyl acetate, propylene glycol methyl ether acetate, ethyl benzoate, isopropyl benzoate, dioctyl phthalate, butyl levulinate, dibutyl hexanoate, and isooctyl butyrate; and / or the polar solvent includes one or more of water, alcohol compounds, ether compounds, and ester compounds; the alcohol compounds include one or more of trimethoxybutanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, and cresol; the ether compounds include one or more of diethyl ether, ethylene glycol dimethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethylene oxide, and tetrahydrofuran; the ester compounds include one or more of ethyl acetate, propylene glycol methyl ether acetate, ethyl benzoate, isopropyl benzoate, dioctyl phthalate, butyl levulinate, dibutyl hexanoate, and isooctyl butyrate; and / or the polarity of the polar solvent is greater than the polarity of the first solvent.

7. The preparation method according to claim 6, characterized in that, The luminescent semiconductor particles include one or more of an organic luminescent material and a quantum dot; the organic luminescent material includes one or more of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridineiridium(III)], 4,4',4”-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridineiridium], diaryl anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, TADF material, a polymer containing B-N covalent bonds, HLCT material, Exciplex luminescent material; the quantum dot includes one or more of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite-type semiconductor material. The material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot are each independently selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The shell of the core-shell structure quantum dot is one or more layers; the II-VI group compounds include one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, 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 include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe.The III-V compounds include one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI compounds include one or more of CuInS; 2 , CuInSe 2 and AgInS 2 ; the perovskite semiconductor materials include doped or undoped inorganic perovskite semiconductors, organic-inorganic hybrid perovskite semiconductors; the structural general formula of the inorganic perovskite semiconductor is AMX 3 , where A is a Cs + ion, M is a divalent metal cation selected from Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ one or more of them, and X is a halogen anion selected from Cl - , Br - , I - one or more of them; the structural general formula of the organic-inorganic hybrid perovskite semiconductor is BMX 3 , where B is an organic amine cation selected from CH 3 (CH 2 ) n-2 NH 3 + or [NH 3 (CH 2 ) n NH 3 2+ , where n≥2, M is a divalent metal cation selected from Pb 2+ , Sn 2+ , Cu 2+ ​, Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ one or more of, X is a halogen anion, selected from Cl - , Br - , one or more of I-; and / or The P-type semiconductor particles include 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent material, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS doped with s-MoO 3 derivatives, poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine, spiro-NPB, nanocrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfides, metal selenides and metal nitrides, one or more of which, the metal oxides in the second doped metal oxide particles and the metal oxides in the second undoped metal oxide particles each independently include MoO 3 、WO 3 、NiO、CrO 3 、CuO、V 2 O 5 one or more of which, the doping elements in the second doped metal oxide particles include one or more of Mo, W, Ni, Cr, Cu, V, and the metal sulfides include CuS, MoS 3 , WS 3 one or more of the following, the metal selenide includes MoSe 3 , WSe 3 one or more of the following, the metal nitride includes p-type gallium nitride; and / or The N-type semiconductor particles include one or more of a first doped metal oxide particle, a first undoped metal oxide particle, a Group IIB-VIA semiconductor material, a Group IIIA-VA semiconductor material, and a Group IB-IIIA-VIA semiconductor material. The material of the first undoped metal oxide particle includes one or more of ZnO, TiO 2 , SnO 2 , ZrO 2 , Ta 2 O 5 ; and the metal oxide in the first doped metal oxide particle includes one or more of ZnO, TiO 2 , SnO 2 , ZrO 2 , Ta 2 O 5 , Al 2 O 3 . The doping element in the first doped metal oxide particle includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The Group IIB-VIA semiconductor material includes one or more of ZnS, ZnSe, and CdS. The Group IIIA-VA semiconductor material includes one or more of InP and GaP. The Group IB-IIIA-VIA semiconductor material includes one or more of CuInS and CuGaS.

8. The preparation method according to claim 5, characterized in that the molar ratio of the semiconductor particles to the ligand is 1:(1 - 5); and / or in the semiconductor particle dispersion, the mass fraction of the semiconductor particles is 5% - 20%; and / or the volume ratio of the semiconductor particle dispersion to the polar solvent is 1:(1 - 30); and / or the mixing time of the semiconductor particle dispersion and the polar solvent is 10 min - 30 min; and / or the mixing temperature of the semiconductor particle dispersion and the polar solvent is 25°C - 50°C; and / or the voltage of the second electric field is 1 V - 10 V.

9. The preparation method according to claim 2, characterized in that Before the charged semiconductor particles enter the first electric field, it further includes making the charged semiconductor particles enter a third electric field at a second velocity V 2 The direction of the second velocity V 2 is parallel to the direction of the third electric field; and / or, the second velocity V 2 is 1 cm / s to 10 cm / s, and / or, the voltage of the third electric field is 20 V to 30 V.

10. The preparation method according to claim 9, characterized in that the deposition of the charged semiconductor particles passing through the first electric field to form a thin film includes: the charged semiconductor particles passing through the first electric field are deposited in the pixel opening to form a thin film; the length of the pixel opening is 100 μm - 200 μm, the width is 500 μm - 800 μm, and the depth is 200 nm - 300 nm, and the pixel opening is located in or outside the first electric field; and / or The minimum radius r of the charged semiconductor particles of the N particle sizes min =(qV / (2πε 0 ))^ 1 / 2 ×(m / 2E)^ 1 / 2 ×(l / h)^ 1 / 2 ×sinθ; The maximum radius r max =[(2 / 3)×(qV / (2πε 0 ))^ 1 / 2 ×(m / 2E)^ 1 / 2 ×(l / h)^ 1 / 2 ×sin(2θ)] + h / 2, where sinθ = h / 2L, q is the charge of the charged semiconductor particle, V is the potential difference of the third electric field, ε 0 is the vacuum permittivity, m is the mass of the charged semiconductor particle, E is the electric field strength of the third electric field, l is the depth of the pixel opening, h is the width perpendicular to the electric field direction of the first electric field, L is the length along the electric field direction of the first electric field, and θ is the angle between the tangent of the movement trajectory of the charged semiconductor particle and the direction perpendicular to the electric field direction of the first electric field.

11. A thin film preparation device, characterized in that it includes a charging unit, a turning unit and a substrate arranged in sequence; the charging unit includes a third electric field for charging the charged semiconductor particles; the turning unit includes a first electric field for turning and depositing the charged semiconductor particles; the substrate is used to receive the charged semiconductor particles.

12. The preparation device according to claim 11, characterized in that the preparation device further includes an injection unit, and the injection unit is arranged adjacent to the charging unit for injecting the charged semiconductor particles into the charging unit; and / or the preparation device further includes an acceleration unit, and the acceleration unit is arranged between the charging unit and the turning unit; the acceleration unit includes a second electric field, and the direction of the second electric field intersects with the direction of the first electric field; and / or the preparation device further includes a moving unit for moving the substrate; and / or the turning unit further includes a magnetic field, and the magnetic field and the first electric field form an electromagnetic field.

13. The preparation device according to claim 12, characterized in that the direction of the second electric field is perpendicular to the direction of the first electric field; and / or the injection unit includes one or more of an injection pump and a stamping pump; and / or the acceleration unit includes a first metal plate and a second metal plate arranged opposite to each other, and the first metal plate and the second metal plate define the second electric field. The first metal plate is provided with a first notch for connecting the charging unit and the acceleration unit, and the second metal plate is provided with a second notch for connecting the charging unit and the turning unit; and / or the moving unit includes a stepping machine; and / or the turning unit includes a third metal plate and a fourth metal plate arranged relatively parallel to each other, and the first electric field is defined between the third metal plate and the fourth metal plate; The ratio of the length of the third metal plate and the fourth metal plate to the distance between the third metal plate and the fourth metal plate is (10 - 15):1; and / or The direction of the magnetic field is parallel to the direction of the first electric field, and the intensity of the magnetic field is 500G - 1000G; and / or The substrate has a plurality of pixel openings for receiving the charged semiconductor particles. The length of the pixel opening is 100μm - 200μm, the width is 500μm - 800μm, and the depth is 200nm - 300nm. The substrate is disposed in or outside the first electric field.

14. A thin film Characterized in that It is prepared by the preparation method according to any one of claims 1 to 10, or is prepared by the preparation device according to any one of claims 11 to 13.

15. An optoelectronic device Characterized in that It includes a first electrode, a functional layer, and a second electrode stacked. The functional layer is prepared by the preparation method according to any one of claims 1 to 10.

16. The optoelectronic device according to claim 15 Characterized in that The functional layer includes one or more of a light-emitting layer, a first carrier functional layer, and a second carrier functional layer. The first carrier functional layer is disposed between the first electrode and the light-emitting layer, and the second carrier functional layer is disposed between the light-emitting layer and the second electrode; the first carrier functional layer is a hole functional layer, and the second carrier functional layer is an electron functional layer, or the second carrier functional layer is a hole functional layer, and the first carrier functional layer is an electron functional layer; one or more of the light-emitting layer, the first carrier functional layer, and the second carrier functional layer are prepared by the preparation method according to any one of claims 1 to 10; and / or The materials of the first electrode and the second electrode respectively include one or more of metal, carbon material, and metal oxide; the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes one or more of graphite, carbon nanotube, graphene, and carbon fiber; the metal oxide includes a metal oxide electrode or a composite electrode with a metal sandwiched between doped or undoped transparent metal oxides, and the material of the metal oxide electrode includes one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO 3 and one or more of AMO, and the composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO 2 / Ag / TiO 2 and TiO 2 / Al / TiO 2 among others.

17. A display device Characterized in that It includes the optoelectronic device according to any one of claims 15 to 16.

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