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

Abstract

The invention discloses a thin film and a preparation method thereof, a photoelectric device and a display device, and relates to the technical field of display. Materials of the thin film comprise a first quantum dot material and a second quantum dot material, the first quantum dot material comprises first quantum dots and Lewis acid ligands combined on the surfaces of the first quantum dots, and the second quantum dot material comprises second quantum dots and Lewis base ligands combined on the surfaces of the second quantum dots. The film provided by the invention comprises the first quantum dot material and the second quantum dot material at the same time, and the first quantum dot and the second quantum dot are orderly arranged through interaction of the lewis acid ligand in the first quantum dot material and the lewis base ligand in the second quantum dot material, so that the luminescence performance of the film can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of display technologies, and particularly to a thin film, a preparation method thereof, 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 their excellent display performances such as self-luminescence, simple structure, ultra-thinness, fast response speed, wide viewing angle, low power consumption, and flexible display, OLEDs have become the mainstream technology in the field of display technologies. QLEDs have the advantages of saturated emission light color and adjustable wavelength, and high photoluminescence and electroluminescence quantum yields. In recent years, they have become strong competitors of OLEDs.

[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. Usually, there is no strong interaction between adjacent homoligand quantum dot individuals. Therefore, the quantum dots in the light-emitting layer of QLEDs are usually disordered, and the disordered self-assembly will lead to uneven distribution of quantum dots in the light-emitting layer, thereby affecting the light-emitting efficiency of optoelectronic devices.

[0004] Currently, the light-emitting efficiency of optoelectronic devices is relatively low and needs to be further improved. Summary of the Invention

[0005] In view of this, this application provides a thin film, aiming to improve the problem of relatively low light-emitting efficiency of existing optoelectronic devices.

[0006] An embodiment of this application is implemented as follows. A thin film, the material of the thin film includes a first quantum dot material and a second quantum dot material. The first quantum dot material includes a first quantum dot and a Lewis acid ligand bonded to the surface of the first quantum dot. The second quantum dot material includes a second quantum dot and a Lewis base ligand bonded to the surface of the second quantum dot.

[0007] An embodiment of this application also provides a preparation method of a thin film, including:

[0008] Providing a substrate;

[0009] A first quantum dot material and a second quantum dot material are provided. The first quantum dot material includes first quantum dots and Lewis acid ligands bonded to the surfaces of the first quantum dots. The second quantum dot material includes second quantum dots and Lewis base ligands bonded to the surfaces of the second quantum dots. The first quantum dot material and the second quantum dot material are disposed on the substrate to obtain a thin film.

[0010] An embodiment of the present application further provides an optoelectronic device, including a first electrode, a light-emitting layer, and a second electrode which are stacked. The light-emitting layer includes the above-mentioned thin film, or includes a thin film prepared by the above-mentioned preparation method.

[0011] The thin film provided by the present application includes both the first quantum dot material and the second quantum dot material. The Lewis acid ligands in the first quantum dot material and the Lewis base ligands in the second quantum dot material interact to enable the first quantum dots and the second quantum dots to be arranged in an orderly manner, which can effectively improve the light-emitting performance of the thin film. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description 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.

[0013] Figure 1 is a flowchart of the preparation method of the thin film provided by the embodiment of the present application;

[0014] Figure 2 is a schematic structural diagram of the optoelectronic device provided by the embodiment of the present application;

[0015] Figure 3 is a schematic structural diagram of another optoelectronic device provided by the embodiment of the present application.

[0016] Reference Signs:

[0017] First electrode 10; Light-emitting layer 20; Second electrode 30; Hole functional layer 40; Electron functional layer 50. Detailed Embodiments

[0018] 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. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. 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.

[0019] In the present application, unless otherwise stated, the orientation terms such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of the present application, the term "including" 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.

[0020] 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.

[0021] In the present application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b, or c", or, "at least one (item) of a, b, and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0022] The various embodiments of the present 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 the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub - ranges and single values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0023] The technical solution of the present application is as follows:

[0024] In a first aspect, an embodiment of the present application provides a thin film. The material of the thin film includes a first quantum dot material and a second quantum dot material. The first quantum dot material includes a first quantum dot and a Lewis acid ligand bonded to the surface of the first quantum dot. The second quantum dot material includes a second quantum dot and a Lewis base ligand bonded to the surface of the second quantum dot.

[0025] The thin film provided by the present application includes both a first quantum dot material and a second quantum dot material. The Lewis acid ligand in the first quantum dot material and the Lewis base ligand in the second quantum dot material interact with each other to arrange the first quantum dot and the second quantum dot in an orderly manner, which can effectively improve the luminescence performance of the thin film.

[0026] In some embodiments, the first quantum dot material and the second quantum dot material are connected by the electrostatic interaction of the Lewis acid ligand and the Lewis base ligand. In other words, the interaction between the Lewis acid ligand in the first quantum dot material and the Lewis base ligand in the second quantum dot material is an electrostatic adsorption interaction.

[0027] In some embodiments, the mass ratio of the first quantum dot material to the second quantum dot material is (0.9 - 1.2):1. For example, it can be 0.92:1, 1.18:1, 0.95:1, 1.15:1, 0.98:1, 1.12:1, 0.99:1, 1.11:1, 1:1, 1.1:1, etc. Within the range of the mass ratio, it is beneficial for the Lewis acid ligand in the first quantum dot material and the Lewis base ligand in the second quantum dot material to be fully attracted by electrostatic interaction for highly ordered self-assembly.

[0028] In some embodiments, the general formula of the Lewis acid ligand is R 1 -R 2 -R 3 . The R 1 is a first anchoring group connected to the surface of the first quantum dot, and the R 3 is a Lewis acid group.

[0029] Correspondingly, the general formula of the Lewis base ligand is R 4 -R 5 -R 6 . The R 4 is a second anchoring group connected to the surface of the second quantum dot, and the R 6 is a Lewis base group.

[0030] In some embodiments, the first quantum dot and the second quantum dot each independently include one or more of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite-type semiconductor material.

[0031] 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 can be respectively selected from, but not limited to, 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.

[0032] 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.

[0033] The perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors. 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+ or more of them, and X is a halogen anion selected from Cl - , Br - , I - 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

[0034] [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 them, X is a halogen anion, selected from Cl - 、Br - 、I - One or more of them.

[0035] In some embodiments, the average particle sizes of the first quantum dots and the second quantum dots are both 3 nm to 20 nm, and for example, they can be 4 nm, 18 nm, 5 nm, 16 nm, 6 nm, 15 nm, 8 nm, 14 nm, 10 nm, 12 nm, etc.

[0036] In some embodiments, the R 1 and the R 4 each independently include one or more of a mercapto group, a phosphate group, a sulfonic acid group, and a phosphonic acid group. It can be understood that the binding energy between the R 1 and the R 4 and the surface of the quantum dot shell is relatively large. After being anchored on the quantum dot shell, the overall energy of the quantum dots is relatively low and the stability is high.

[0037] It should be noted that the materials and average particle sizes of the first quantum dots and the second quantum dots can be the same or different. The R 1 and the R 4 can be the same or different.

[0038] In some embodiments, the Lewis acid group includes a carboxyl group.

[0039] In some embodiments, the Lewis base group includes an amino group.

[0040] It can be understood that -COOH can have an electrostatic interaction with -NH 2 to form -(COO(NH 4+ ))-, thereby promoting the ordered self-assembly of the first quantum dot material and the second quantum dot material.

[0041] In some embodiments, the R 2 is selected from a straight-chain or branched-chain alkyl group with 6 to 25 carbon atoms in the main chain, a straight-chain or branched-chain heteroalkyl group with 6 to 25 carbon atoms in the main chain, a straight-chain or branched-chain alkenyl group with 6 to 25 carbon atoms in the main chain, a straight-chain or branched-chain heteroalkenyl group with 6 to 25 carbon atoms in the main chain, a straight-chain or branched-chain alkynyl group with 6 to 25 carbon atoms in the main chain, and a straight-chain or branched-chain heteroalkynyl group with 6 to 25 carbon atoms in the main chain, one or more of them.

[0042] In some embodiments, the R 2Selected from one or more of a straight-chain or branched alkyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 8 to 20 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 8 to 20 carbon atoms in the main chain.

[0043] In some embodiments, the R 2 Selected from one or more of a straight-chain or branched alkyl group having 10 to 15 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 10 to 15 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 10 to 15 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 10 to 15 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 10 to 15 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 10 to 15 carbon atoms in the main chain.

[0044] In some embodiments, the R 2 Selected from one or more of a straight-chain or branched alkyl group having 11 to 14 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 11 to 14 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 11 to 14 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 11 to 14 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 11 to 14 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 11 to 14 carbon atoms in the main chain.

[0045] In some embodiments, the R 2 Selected from one or more of a straight-chain or branched alkyl group having 12 to 13 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 12 to 13 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 12 to 13 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 12 to 13 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 12 to 13 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 12 to 13 carbon atoms in the main chain.

[0046] In some embodiments, the R 5 Selected from one or more of a straight-chain or branched alkyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 10 to 20 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 10 to 20 carbon atoms in the main chain.

[0047] In some embodiments, the R 5Selected from one or more of a straight-chain or branched alkyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 8 to 20 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 8 to 20 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 8 to 20 carbon atoms in the main chain.

[0048] In some embodiments, the R 5 Selected from one or more of a straight-chain or branched alkyl group having 10 to 18 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 10 to 18 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 10 to 18 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 10 to 18 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 10 to 18 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 10 to 18 carbon atoms in the main chain.

[0049] In some embodiments, the R 5 Selected from one or more of a straight-chain or branched alkyl group having 12 to 16 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 12 to 16 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 12 to 16 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 12 to 16 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 12 to 16 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 12 to 16 carbon atoms in the main chain.

[0050] In some embodiments, the R 5 Selected from one or more of a straight-chain or branched alkyl group having 13 to 15 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 13 to 15 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 13 to 15 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 13 to 15 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 13 to 15 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 13 to 15 carbon atoms in the main chain.

[0051] In some embodiments, the heteroatoms in the heteroalkyl group, the heteroalkenyl group, and the heteroalkynyl group respectively include one or several of O, N, P, S, and Si.

[0052] In some embodiments, the Lewis acid ligand includes one or several of 12-mercaptododecanoic acid and 12-carboxydodecylphosphonic acid.

[0053] Further, the preparation method of the 12-carboxydodecylphosphonic acid is as follows: Take 1.05 mmol of N,N'-dicyclohexylcarbodiimide and 1.05 mmol of 2-mercaptopyridine-N-oxide, dissolve them in 4 mL of dichloromethane to obtain a mixed solution; separately take 4 mL of a dichloromethane solution of dodecanoic acid with a concentration of 0.25 mol / L, and slowly add it to the mixed solution at 0 °C; after reacting for 90 min, separate and purify the product A through a chromatographic column; dissolve 1 mmol of white phosphorus in 10 mL of tetrahydrofuran under an argon atmosphere, add the product A thereto at 0 °C, then slowly add 0.33 mL of 30% hydrogen peroxide solution, and then reflux the reaction solution for 12 h; rotary evaporate to leave the aqueous phase part, add 20 mL of ethyl acetate to extract the product to obtain 12-carboxydodecylphosphonic acid.

[0054] In some embodiments, the Lewis base ligand includes one or more of 12-mercaptododecylamine and 12-aminododecylphosphonic acid.

[0055] Further, the preparation method of the 12-mercaptododecylamine is as follows: Take 1 mmol of 12-mercaptododecanoic acid and mix it with 4 mL of toluene. After cooling the solution to 0 °C, add 1.05 mmol of diphenylphosphoryl azide, heat it to 80 °C and react for 6 h, add 0.1 mmol of triphenylphosphine and react for 1 h, and purify it through column chromatography separation and recrystallization methods to obtain 12-mercaptododecylamine.

[0056] Further, the preparation method of the 12-aminododecylphosphonic acid is as follows: Take 1 mmol of 12-mercaptododecylphosphonic acid and mix it with 10 mL of chloroform. After heating the solution to 50 °C, add 1.05 mmol of dithiothreitol; after reacting for 6 h, cool it to -78 °C; add 1.1 mmol of sodium borohydride and react for 1 h; heat it to room temperature, and purify it through column chromatography separation and recrystallization methods to obtain 12-aminododecylphosphonic acid.

[0057] In some embodiments, in the first quantum dot material, the mass fraction of the Lewis acid ligand is 10% - 15%, for example, it can be 11%, 12%, 13%, 14%, etc. Within the range of the mass fraction, the surface defects of the first quantum dot can be effectively passivated, the injection barriers of electrons and holes can be reduced, and the turn-on voltage of the optoelectronic device can be reduced.

[0058] In some embodiments, in the second quantum dot material, the mass fraction of the Lewis base ligand is 10% - 15%, for example, it can be 11%, 12%, 13%, 14%, etc. Within the range of the mass fraction, the surface defects of the second quantum dot can be effectively passivated, the injection barriers of electrons and holes can be reduced, and the turn-on voltage of the optoelectronic device can be reduced.

[0059] Second aspect, please refer toFigure 1 , an embodiment of the present application provides a method for preparing a thin film, including:

[0060] S11. Provide a substrate;

[0061] S12. Provide a first quantum dot material and a second quantum dot material. The first quantum dot material includes first quantum dots and Lewis acid ligands bound to the surfaces of the first quantum dots. The second quantum dot material includes second quantum dots and Lewis base ligands bound to the surfaces of the second quantum dots. Set the first quantum dot material and the second quantum dot material on the substrate to obtain a thin film.

[0062] In the method for preparing a thin film provided by the present application, when the first quantum dot material and the second quantum dot material are set on the substrate, the Lewis acid ligands in the first quantum dot material and the Lewis base ligands in the second quantum dot material generate an electrostatic attraction, causing the first quantum dot material and the second quantum dot material to perform an ordered self-assembly on the substrate. The first quantum dots and the second quantum dots are arranged in an orderly manner, which can improve the luminescence performance of the thin film.

[0063] In S11:

[0064] In some embodiments, the substrate includes a first electrode 10.

[0065] In some other embodiments, the substrate includes a first electrode 10 and a first carrier functional layer 40.

[0066] In S12:

[0067] In some embodiments, the method for preparing the first quantum dot material includes:

[0068] S121. Provide a first quantum dot material precursor, which includes first quantum dots and a first ligand connected to the surfaces of the first quantum dots;

[0069] S122. Mix the first quantum dot material precursor, Lewis acid ligands, and a first solvent to obtain the first quantum dot material.

[0070] In S121:

[0071] It can be understood that during the growth and preparation process of quantum dots, ligands are introduced to promote the synthesis and growth of quantum dots. After the growth of quantum dots is completed, the ligands are bound to the surfaces of the quantum dots through electrostatic interactions.

[0072] In some embodiments, the first ligand includes one or more of oleic acid, oleylamine, and tri-n-octylphosphine.

[0073] It should be noted that oleic acid binds to the surface of the quantum dots through its carboxyl group, oleylamine binds to the surface of the quantum dots through its amino group, and tri-n-octylphosphine binds to the surface of the quantum dots through phosphorus.

[0074] In the S122:

[0075] In some embodiments, after the first quantum dot material precursor, the Lewis acid ligand and the first solvent are mixed, the mass concentration of the first quantum dot material precursor is 5 mg / mL to 200 mg / mL, and can be, for example, 10 mg / mL, 180 mg / mL, 10 mg / mL, 160 mg / mL, 50 mg / mL, 150 mg / mL, 60 mg / mL, 120 mg / mL, 80 mg / mL, 100 mg / mL, etc.

[0076] In some embodiments, the mass ratio of the first quantum dot material precursor to the Lewis acid ligand is (8 to 12):1; for example, it can be 9:1, 10:1, 11:1, etc. Within the range of the mass ratio, it is beneficial for the Lewis acid ligand to bind to the surface of the first quantum dot.

[0077] In some embodiments, the first solvent includes one or more of n-octane, dimethylformamide, ethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, cresol.

[0078] In some embodiments, the temperature for mixing the first quantum dot material precursor, the Lewis acid ligand and the first solvent is 20°C to 120°C, and can be, for example, 30°C, 110°C, 40°C, 100°C, 50°C, 90°C, 60°C, 80°C, 65°C, 70°C, etc. The time is 10 min to 180 min, and can be, for example, 20 min, 160 min, 30 min, 150 min, 50 min, 140 min, 60 min, 120 min, 80 min, 100 min, etc. Thus, under the conditions of the mixing, it is beneficial for the first ligand and the Lewis acid ligand to be fully replaced, so that the Lewis acid ligand binds to the surface of the first quantum dot.

[0079] It should be noted that the first anchoring group in the Lewis acid ligand has a greater binding energy with the surface of the first quantum dot shell than the carboxyl group, amino group, and phosphorus in the first ligand. After the first anchoring group is anchored on the first quantum dot shell, the overall energy of the first quantum dot is lower and the stability is higher. Therefore, the Lewis acid ligand can exchange with the first ligand, so that the Lewis acid ligand binds to the surface of the first quantum dot.

[0080] In some embodiments, after the first quantum dot material precursor, the Lewis acid ligand, and the first solvent are mixed, a first precipitating agent is further added.

[0081] In some embodiments, the first precipitating agent includes one or more of straight-chain alkanes having C 6 ~C 10 , benzene, toluene, xylene, chloroform.

[0082] In some embodiments, after adding the first precipitating agent, washing is further included. The washing can effectively remove the first solvent and the first ligand to obtain a first quantum dot material with high purity.

[0083] In some embodiments, the method for preparing the second quantum dot material includes:

[0084] S123. Provide a second quantum dot material precursor, where the second quantum dot material precursor includes a second quantum dot and a second ligand connected to the surface of the second quantum dot;

[0085] S124. Mix the second quantum dot material precursor, the Lewis base ligand, and the second solvent to obtain a second quantum dot material.

[0086] In S123:

[0087] In some embodiments, the second ligand includes one or more of oleic acid, oleylamine, tri-n-octylphosphine.

[0088] In S124:

[0089] In some embodiments, after the second quantum dot material precursor, the Lewis base ligand, and the second solvent are mixed, the mass concentration of the second quantum dot material precursor is 5 mg / mL to 200 mg / mL, for example, it can be 10 mg / mL, 180 mg / mL, 10 mg / mL, 160 mg / mL, 50 mg / mL, 150 mg / mL, 60 mg / mL, 120 mg / mL, 80 mg / mL, 100 mg / mL, etc.

[0090] In some embodiments, the mass ratio of the second quantum dot material precursor to the Lewis base ligand is (8 to 12):1; for example, it can be 9:1, 10:1, 11:1, etc. Within the range of the mass ratio, it is beneficial for the Lewis base ligand to be attached to the surface of the second quantum dot.

[0091] In some embodiments, the second solvent includes one or more of n-octane, dimethylformamide, ethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, and cresol.

[0092] In some embodiments, the temperature for mixing the second quantum dot material precursor, the Lewis base ligand, and the second solvent is 20°C to 120°C, and can be, for example, 30°C, 110°C, 40°C, 100°C, 50°C, 90°C, 60°C, 80°C, 65°C, 70°C, etc. The time is 10 min, 180 min, and can be, for example, 20 min, 160 min, 30 min, 150 min, 50 min, 140 min, 60 min, 120 min, 80 min to 100 min, etc. Thus, under the conditions of the above mixing, it is beneficial for the second ligand and the Lewis base ligand to be fully replaced, so that the Lewis base ligand binds to the surface of the second quantum dot.

[0093] In some embodiments, after mixing the second quantum dot material precursor, the Lewis base ligand, and the second solvent, a second precipitating agent is further added.

[0094] In some embodiments, the second precipitating agent includes one or more of C6-C10 straight-chain alkanes, benzene, toluene, xylene, and chloroform.

[0095] In some embodiments, after adding the second precipitating agent, washing is further included. The washing can effectively remove the second solvent and the second ligand, obtaining a second quantum dot material with high purity.

[0096] It can be understood that the method for obtaining the thin film can adopt conventional techniques in the art, such as chemical methods or physical methods. Among them, chemical methods include chemical vapor deposition, successive ionic layer adsorption and reaction, anodic oxidation, electrodeposition, and coprecipitation. Physical methods include physical coating methods and solution methods. Among them, physical coating methods include: thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion coating, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.; solution methods can be spin coating, printing, inkjet printing, blade coating, printing, dip coating, immersion, spraying, roll coating, casting, slot die coating, and bar coating, etc.

[0097] In at least one embodiment, the method for obtaining the thin film is a solution method.

[0098] Specifically, it includes: providing a first quantum dot material and a second quantum dot material, mixing them with a third solvent to obtain a quantum dot material solution; disposing the quantum dot material solution on the substrate to obtain a thin film.

[0099] In some embodiments, the third solvent includes one or more of n-octane, dimethylformamide, ethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, and cresol.

[0100] In some embodiments, in the quantum dot material solution, the mass concentration of the first quantum dot material and the second quantum dot material is 15 mg / mL to 75 mg / mL, for example, it can be 20 mg / mL, 70 mg / mL, 25 mg / mL, 65 mg / mL, 30 mg / mL, 60 mg / mL, 35 mg / mL, 55 mg / mL, 40 mg / mL, 50 mg / mL, etc. Within this mass concentration range, it is beneficial to the full dissolution of the first quantum dot material and the second quantum dot material.

[0101] In some embodiments, in the quantum dot material solution, the mass ratio of the first quantum dot material to the second quantum dot material is (0.9 to 1.2):1, for example, it can be 0.92:1, 1.18:1, 0.95:1, 1.15:1, 0.98:1, 1.12:1, 0.99:1, 1.11:1, 1:1, 1.1:1, etc.

[0102] In a third aspect, please refer to Figure 2 , an optoelectronic device provided by an embodiment of the present application includes a first electrode 10, a light-emitting layer 20, and a second electrode 30 that are stacked, and the light-emitting layer 20 is prepared by the method for preparing the thin film described above.

[0103] In the optoelectronic device provided by the present application, the light-emitting layer 20 simultaneously includes a first quantum dot material and a second quantum dot material. The Lewis acid ligand in the first quantum dot material and the Lewis base ligand in the second quantum dot material interact with each other, enabling the first quantum dot and the second quantum dot to be arranged orderly, thereby improving the light-emitting performance of the light-emitting layer 20, and further improving the light-emitting uniformity and light-emitting efficiency of the optoelectronic device.

[0104] In some embodiments, please refer to Figure 3 , the optoelectronic device further includes a first carrier functional layer, and the first carrier functional layer is disposed between the first electrode 10 and the light-emitting layer 20.

[0105] In some embodiments, the optoelectronic device further includes a second carrier functional layer, which is disposed between the light-emitting layer 20 and the second electrode 30.

[0106] In some embodiments, the first carrier functional layer is a hole functional layer 40, and the second carrier functional layer is an electron functional layer 50.

[0107] In some other embodiments, the second carrier functional layer is a hole functional layer 40, and the first carrier functional layer is an electron functional layer 50.

[0108] The hole functional layer 40 includes one or more of a hole injection layer and a hole transport layer, and the electron functional layer 50 includes one or more of an electron injection layer and an electron transport layer.

[0109] In some embodiments, the first electrode 10 and the second electrode 30 each independently include one or more of a metal, a carbon material, and a 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, a carbon nanotube, graphene, and carbon fiber; the metal oxide includes a metal oxide electrode or a composite electrode in which a doped or undoped transparent metal oxide sandwiches a metal, and the material of the metal oxide electrode includes one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO 3 and AMO; 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 One or more of them. Herein, " / " represents a stacked structure. For example, AZO / Ag / AZO represents a composite electrode including a sequentially stacked AZO layer, an Ag layer, and an AZO layer.

[0110] In some embodiments, the material of the electronic functional layer 50 includes one or more of doped or undoped semiconductor particles, quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, and hydroxyquinoline compounds. The semiconductor particles include one or more of zinc oxide, barium oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc selenide, indium phosphide, gallium phosphide, and barium titanate. The doping elements include one or more of indium, gallium, aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium.

[0111] In some embodiments, the material of the hole functional layer 40 includes 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 3Derivatives thereof, 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, transition metal oxides, transition metal sulfides, transition metal stannides, doped or undoped zinc oxide, barium oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, lithium titanium 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 selenide, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, barium titanate, quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds, or one or more of them.

[0112] In some embodiments, the thicknesses of the first electrode 10 and the second electrode 30 are each independently 10 nm to 200 nm, and for example, can be 20 nm, 180 nm, 30 nm, 160 nm, 50 nm, 150 nm, 60 nm, 120 nm, 80 nm, 100 nm, etc.

[0113] In some embodiments, the thickness range of the light-emitting layer 20 is 10 nm to 60 nm, and for example, can be 12 nm, 55 nm, 15 nm, 52 nm, 20 nm, 50 nm, 25 nm, 45 nm, 30 nm, 40 nm, etc.

[0114] In some embodiments, the thicknesses of the first charge carrier functional layer and the second charge carrier functional layer are each independently 10 nm to 150 nm, and for example, can be 20 nm, 130 nm, 20 nm, 120 nm, 30 nm, 100 nm, 40 nm, 80 nm, 50 nm, 60 nm, etc.

[0115] Fourthly, an embodiment of the present application further provides a display device, and the display device includes the above optoelectronic device.

[0116] 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.

[0117] The following specifically describes the present application through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0118] Example 1

[0119] Weigh 40 mg of CdSe / ZnS core-shell quantum dot powder with a luminescence wavelength of 580 nm and oleic acid as the ligand. Dissolve it in 1 mL of n-octane and 1 mL of dimethylformamide, then add 20 μL of 12-mercaptododecanoic acid. After stirring at 80 °C for 2 hours, take out the lower-layer dimethylformamide solution, precipitate the quantum dots with n-heptane, and then use the cleaning method of redispersing the quantum dots with dimethylformamide to clean the quantum dots twice to obtain CdSe / ZnS core-shell quantum dots with 12-mercaptododecanoic acid as the main ligand dispersed in dimethylformamide, and the mass fraction of 12-mercaptododecanoic acid is 12%;

[0120] Weigh 40 mg of CdSe / ZnS core-shell quantum dot powder with a luminescence wavelength of 580 nm and oleic acid as the ligand. Dissolve it in 1 mL of n-octane and 1 mL of dimethylformamide, then add 20 μL of 12-mercaptododecylamine. After stirring at 80 °C for 2 hours, take out the lower-layer dimethylformamide solution, precipitate the quantum dots with n-heptane, and then use the cleaning method of redispersing the quantum dots with dimethylformamide to clean the quantum dots twice to obtain CdSe / ZnS core-shell quantum dots with 12-mercaptododecylamine as the main ligand dispersed in dimethylformamide, and the mass fraction of 12-mercaptododecylamine is 12%;

[0121] Mix the 12-mercaptododecanoic acid ligand quantum dots and the 12-mercaptododecylamine ligand quantum dots in a mass ratio of 1:1 to obtain a quantum dot solution for preparation, with a concentration of 40 mg / mL. Spin-coat the quantum dot solution at a rotation speed of 3500 rpm for 30 s, and anneal at 80 °C for 30 min to form a film with a thickness of 50 nm.

[0122] Examples 2 - 4

[0123] Examples 2 - 4 are basically the same as Example 1, the only difference being that in Examples 2 - 3, 12-mercaptododecanoic acid is replaced with 12-carboxydodecylphosphonic acid and 12-aminododecylphosphonic acid respectively; in Example 4, the CdSe / ZnS core-shell quantum dots are replaced with InP / ZnS core-shell quantum dots.

[0124] Examples 5 - 6

[0125] Examples 5 - 6 are basically the same as Example 1, the only difference being that the mass fractions of 12-mercaptododecanoic acid in Examples 5 - 6 are 10% and 15% respectively.

[0126] Comparative Examples 1 - 3

[0127] Comparative Examples 1 to 3 are basically the same as Example 1, except that in Comparative Examples 1 to 3, the ligands in the materials of the thin films contain only oleic acid, 12-mercaptododecanoic acid, and 12-mercaptododecylamine, respectively.

[0128] The grazing incidence small angle X-ray scattering experiment was used to measure the average distance between quantum dots in the thin films of Examples 1 to 6 and Comparative Examples 1 to 3, and the results are shown in Table 1.

[0129] Table 1

[0130]

[0131] As can be seen from Table 1:

[0132] From Example 1 and Comparative Examples 1 to 3, it can be seen that using quantum dots containing Lewis ligands and quantum dots containing Lewis base ligands together as the material of the thin film can significantly reduce the average distance between quantum dots compared with using quantum dots containing a single ligand as the material of the thin film; it shows that the thin film provided by this application can enable highly ordered self-assembly of quantum dots;

[0133] From Examples 1 to 4 and Comparative Example 1, it can be seen that by respectively replacing the Lewis acid ligand and the Lewis base ligand in Example 1, the average distance between quantum dots in the thin film does not change significantly. This may be because the Lewis acid ligand and the Lewis base ligand are mainly combined through electrostatic interaction to achieve the ordered self-assembly of quantum dots;

[0134] From Example 1, Examples 5 to 6 and Comparative Example 1, it can be seen that by changing the ratio of the Lewis acid ligand and the Lewis base ligand, the distance between quantum dots is still lower than that in Comparative Example 1, and the thin film is denser and more complete, which is beneficial for the thin film to fully exert its beneficial properties.

[0135] Device Example 1

[0136] This device example provides an optoelectronic device, and the preparation method is as follows:

[0137] 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 110 nm;

[0138] Set a TFB solution with a concentration of 8 mg / mL on the ITO anode, perform spin coating, the rotation speed of spin coating is 5000 rpm, the time is 30 s, and then perform annealing, the annealing temperature is 150 °C, and the annealing time is 15 min to obtain a hole functional layer with a thickness of 70 nm;

[0139] Prepare a light-emitting layer on the hole functional layer according to the method of Example 1;

[0140] A 100 mL ethanol dispersion of ZnO with a concentration of 30 mg / mL was set on the light-emitting layer and spin-coated at a rotation speed of 3000 rpm for 30 s, and annealed at 80 °C for 30 min to form an electron functional layer with a thickness of 70 nm;

[0141] On the electron functional layer, silver was evaporated with a vacuum degree not higher than 3×10 -4 Pa at a speed of 1 Å / s and a thickness of 100 nm to obtain a cathode;

[0142] Encapsulation was carried out to obtain an optoelectronic device.

[0143] Device Examples 2 to 6

[0144] Device Examples 2 to 6 are basically the same as Device Example 1, except that in Device Examples 2 to 6, the light-emitting layers were prepared by referring to the methods of Examples 2 to 6 respectively.

[0145] Device Example 7

[0146] This device example is basically the same as Device Example 1, except that the preparation sequence in this example is: cathode, electron functional layer, light-emitting layer, hole functional layer, and anode.

[0147] Device Comparative Examples 1 to 3

[0148] Device Comparative Examples 1 to 3 are basically the same as Device Example 1, except that in Device Comparative Examples 1 to 3, the light-emitting layers were prepared by referring to the methods of Comparative Examples 1 to 3 respectively.

[0149] Device Comparative Example 4

[0150] This device comparative example is basically the same as Device Comparative Example 1, except that the preparation sequence in this device comparative example refers to Device Example 7.

[0151] The luminous brightness of the optoelectronic devices in Device Examples 1 to 7 and Device Comparative Examples 1 to 4 was tested to obtain the luminous brightness of the optoelectronic devices and their standard deviations. The test results are shown in Table 2.

[0152] Among them, the test method for luminous brightness is: the 2 mm×2 mm light-emitting area of the optoelectronic device was evenly divided into 160 areas of 50 μm×50 μm. The brightness of a single 50 μm×50 μm area was tested using a microscope and a photometer, and the optoelectronic device was moved by a programmable XY-axis motorized displacement platform to enable the photometer to continuously test a total of 160 light-emitting areas. Statistical analysis of the 160 brightness values was performed to obtain the average luminous brightness and its standard deviation.

[0153] Table 2

[0154]

[0155]

[0156] As can be seen from Table 2:

[0157] It can be seen from Device Example 1 and Device Comparative Examples 1-3 that using quantum dots containing a Lewis ligand and quantum dots containing a Lewis base ligand together as the material of the light-emitting layer can significantly improve the luminescence brightness and its uniformity of the optoelectronic device compared with using quantum dots containing a single ligand as the material of the light-emitting layer; although the luminescence brightness of the optoelectronic devices in Device Comparative Examples 2-3 is significantly improved compared with that in Device Comparative Example 1, its standard deviation is too large, indicating that the uniformity of its luminescence brightness is poor, while the standard deviation of the luminescence brightness of Device Example 1 is lower, indicating that its luminescence uniformity is higher;

[0158] It can be seen from Device Examples 1-4 and Device Comparative Example 1 that by respectively replacing the Lewis acid ligand and the Lewis base ligand in Device Example 1, the luminescence brightness of the optoelectronic device is still higher than that of the optoelectronic device in Comparative Example 1 and slightly lower than that of the optoelectronic device in Device Example 1. This may be because the anchoring groups in the Lewis acid ligand and the Lewis base ligand in Device Example 1 are the same, making it easier for the Lewis acid ligand and the Lewis base ligand to bind through electrostatic interaction, realizing the ordered self-assembly of quantum dots, thereby improving the luminescence brightness of the optoelectronic device; using InP / ZnS core-shell quantum dots as the material of the light-emitting layer, the luminescence brightness of its optoelectronic device is slightly lower than that of the optoelectronic device using CdSe / ZnS core-shell quantum dots as the material of the light-emitting layer, but still higher than that of the optoelectronic device in Device Example 1;

[0159] It can be seen from Device Example 1, Device Examples 5-6 and Device Comparative Example 1 that changing the density of the Lewis acid ligand is equivalent to changing the ratio of the Lewis acid ligand and the Lewis base ligand. The luminescence brightness of its optoelectronic device is higher than that in Device Comparative Example 1. However, since not all of the Lewis acid ligand and the Lewis base ligand can effectively bind through electrostatic interaction, the self-assembly effect of its quantum dots is not as good as that in Device Example 1, and its luminescence brightness and luminescence uniformity are slightly worse than those of the optoelectronic device in Example 1;

[0160] It can be seen from Device Example 1, Device Example 7 and Device Comparative Example 4 that the luminescence brightness and luminescence uniformity of the normal optoelectronic device are higher than those of the inverted device, but the luminescence brightness and uniformity of the inverted device in Device Example 7 are higher than those of the optoelectronic device in Device Comparative Example 4.

[0161] The above has introduced in detail the thin film provided by the embodiments of the present application, its preparation method, optoelectronic device and display device. Specific examples are used herein 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 thin film, characterized in that, the material of the thin film comprises a first quantum dot material and a second quantum dot material, the first quantum dot material comprises a first quantum dot and a Lewis acid ligand bound to the surface of the first quantum dot, and the second quantum dot material comprises a second quantum dot and a Lewis base ligand bound to the surface of the second quantum dot.

2. The thin film according to claim 1, characterized in that, the mass ratio of the first quantum dot material to the second quantum dot material is (0.9 - 1.2):1; and / or the average particle size of the first quantum dot is 3nm - 20nm; and / or the average particle size of the second quantum dot is 3nm - 20nm; and / or in the first quantum dot material, the mass fraction of the Lewis acid ligand is 10% - 15%; and / or in the second quantum dot material, the mass fraction of the Lewis base ligand is 10% - 15%.

3. The thin film according to claim 1, characterized in that, The general formula of the Lewis acid ligand is R 1 -R 2 -R 3 , where the R 1 is a first anchoring group, the R 3 is a Lewis acid group, and the Lewis acid group includes a carboxyl group; optionally, the first anchoring group comprises one or more of a mercapto group, a phosphate group, a sulfonic acid group, and a phosphoric acid group; Optionally, the R 2 is selected from one or more of a linear or branched alkyl group having 6 to 25 carbon atoms in the main chain, a linear or branched heteroalkyl group having 6 to 25 carbon atoms in the main chain, a linear or branched alkenyl group having 6 to 25 carbon atoms in the main chain, a linear or branched heteroalkenyl group having 6 to 25 carbon atoms in the main chain, a linear or branched alkynyl group having 6 to 25 carbon atoms in the main chain, and a linear or branched alkynyl heteroalkynyl group having 6 to 25 carbon atoms in the main chain; And / or, the general formula of the Lewis base ligand is R 4 -R 5 -R 6 , where the R 4 is a second anchoring group, the R 6 is a Lewis base group, and the Lewis base group includes an amino group; optionally, the second anchoring group comprises one or more of a mercapto group, a phosphate group, a sulfonic acid group, and a phosphoric acid group; Optionally, the R 5 is selected from one or more of a straight-chain or branched alkyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 6 to 25 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 6 to 25 carbon atoms in the main chain.

4. The thin film according to claim 3, characterized in that, The R 2 is selected from one or more of a straight-chain or branched alkyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 10 to 20 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 10 to 20 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 10 to 20 carbon atoms in the main chain; and / or The R 5 is selected from one or more of a linear or branched alkyl group having 10 to 20 carbon atoms in the main chain, a linear or branched heteroalkyl group having 10 to 20 carbon atoms in the main chain, a linear or branched alkenyl group having 10 to 20 carbon atoms in the main chain, a linear or branched heteroalkenyl group having 10 to 20 carbon atoms in the main chain, a linear or branched alkynyl group having 10 to 20 carbon atoms in the main chain, and a linear or branched alkynyl heteroalkynyl group having 10 to 20 carbon atoms in the main chain; and / or the heteroatoms in the heteroalkyl group, the heteroalkenyl group, and the heteroalkynyl group respectively comprise one or more of O, N, P, S, and Si.

5. The thin film according to claim 1, characterized in that, the Lewis acid ligand comprises one or more of 12-mercaptododecanoic acid and 12-carboxydodecylphosphonic acid; and / or the Lewis base ligand comprises one or more of 12-mercaptododecylamine and 12-aminododecylphosphonic acid; and / or The first quantum dot and the second quantum dot each independently include one or more of a single-structure quantum dot, a core-shell structure quantum dot, and a perovskite 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 selected from one or several of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds; the shell layer of the core-shell structure quantum dot is one or more layers; the II-VI group compounds include one or several 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 several 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 several 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 the following; the core-shell quantum dots 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; the perovskite semiconductor material includes doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors; the structural general formula of the inorganic perovskite semiconductor is AMX 3 , where A is Cs + ion, M is a divalent metal cation selected from Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ one or more of the following, and X is a halogen anion selected from Cl - , Br - , I - one or more of the following; 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 the following, and X is a halogen anion selected from Cl - , Br​ - , I - or one or more of the following.

6. A method for preparing a thin film, characterized in that, comprises: providing a substrate; providing a first quantum dot material and a second quantum dot material, the first quantum dot material comprises a first quantum dot and a Lewis acid ligand bound to the surface of the first quantum dot, and the second quantum dot material comprises a second quantum dot and a Lewis base ligand bound to the surface of the second quantum dot, and disposing the first quantum dot material and the second quantum dot material on the substrate to obtain a thin film.

7. The preparation method according to claim 6, characterized in that, The general formula of the Lewis acid ligand is R 1 -R 2 -R 3 , where R 1 is a first anchoring group, and R 3 is a Lewis acid group, and the Lewis acid group includes a carboxyl group; optionally, the first anchoring group comprises one or more of a mercapto group, a phosphate group, a sulfonic acid group, and a phosphoric acid group; Optionally, the R 2 is selected from one or more of a linear or branched alkyl group having 6 to 25 carbon atoms in the main chain, a linear or branched heteroalkyl group having 6 to 25 carbon atoms in the main chain, a linear or branched alkenyl group having 6 to 25 carbon atoms in the main chain, a linear or branched heteroalkenyl group having 6 to 25 carbon atoms in the main chain, a linear or branched alkynyl group having 6 to 25 carbon atoms in the main chain, and a linear or branched alkynyl heteroalkynyl group having 6 to 25 carbon atoms in the main chain; And / or, the general formula of the Lewis base ligand is R 4 -R 5 -R 6 , where the R 4 is a second anchoring group, the R 6 is a Lewis base group, and the Lewis base group includes an amino group; optionally, the second anchoring group comprises one or more of a mercapto group, a phosphate group, a sulfonic acid group, and a phosphoric acid group; Optionally, the R 5 is selected from one or more of a straight-chain or branched alkyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched heteroalkyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched alkenyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched heteroalkenyl group having 6 to 25 carbon atoms in the main chain, a straight-chain or branched alkynyl group having 6 to 25 carbon atoms in the main chain, and a straight-chain or branched alkynyl heteroalkynyl group having 6 to 25 carbon atoms in the main chain.

8. The preparation method according to claim 6, characterized in that, the Lewis acid ligand comprises one or more of 12-mercaptododecanoic acid and 12-carboxydodecylphosphonic acid; and / or the Lewis base ligand comprises one or more of 12-mercaptododecylamine and 12-aminododecylphosphonic acid.

9. The preparation method according to claim 6, characterized in that, The preparation method of the first quantum dot material includes: providing a first quantum dot material precursor, where the first quantum dot material precursor includes a first quantum dot and a first ligand connected to the surface of the first quantum dot; mixing the first quantum dot material precursor, a Lewis acid ligand, and a first solvent to obtain the first quantum dot material; and / or The preparation method of the second quantum dot material includes: providing a second quantum dot material precursor, where the second quantum dot material precursor includes a second quantum dot and a second ligand connected to the surface of the second quantum dot; mixing the second quantum dot material precursor, a Lewis base ligand, and a second solvent to obtain the second quantum dot material.

10. The preparation method according to claim 9, wherein, the first ligand includes one or several of oleic acid, oleylamine, and tri-n-octylphosphine; and / or the second ligand includes one or several of oleic acid, oleylamine, and tri-n-octylphosphine; and / or in the first quantum dot material, the mass fraction of the Lewis acid ligand is 10% - 15%; and / or in the first quantum dot material, the mass fraction of the Lewis acid ligand is 10% - 15%; and / or the mass ratio of the first quantum dot material precursor to the Lewis acid ligand is (8 - 12):1; and / or the mass ratio of the second quantum dot material precursor to the Lewis base ligand is (8 - 12):1; and / or the first solvent and the second solvent each independently include one or several of n-octane, dimethylformamide, ethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, ethyl acetate, pyrrole, butyric acid, and cresol; and / or after mixing the first quantum dot material precursor, the Lewis acid ligand, and the first solvent, the mass concentration of the first quantum dot material precursor is 5 mg / mL - 200 mg / mL; and / or after mixing the second quantum dot material precursor, the Lewis base ligand, and the second solvent, the mass concentration of the second quantum dot material precursor is 5 mg / mL - 200 mg / mL.

11. The preparation method according to claim 9, wherein, the temperature for mixing the first quantum dot material precursor, the Lewis acid ligand, and the first solvent is 20°C - 120°C; and / or the mixing time of the first quantum dot material precursor, the Lewis acid ligand, and the first solvent is 10 min - 180 min; and / or the temperature for mixing the second quantum dot material precursor, the Lewis base ligand, and the second solvent is 20°C - 120°C; and / or the mixing time of the second quantum dot material precursor, the Lewis base ligand, and the second solvent is 10 min - 180 min.

12. An optoelectronic device, wherein, it includes a first electrode, a light-emitting layer, and a second electrode which are stacked, and the light-emitting layer includes the thin film according to any one of claims 1 to 5, or includes the thin film prepared by the preparation method according to any one of claims 6 to 11.

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