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

Abstract

The embodiment of the invention provides a thin film and a preparation method thereof, a photoelectric device and a display device. The thin film comprises a first modification material and an N-type semiconductor material, the first modification material comprises maleimide and / or maleimide derivatives, the first modification material can play a role of an electron acceptor due to low electron density, and the N-type semiconductor material can play a role of an electron carrier due to good conductivity, so that the conductivity of the first modification material is improved. According to the present invention, the electrons are easily transferred from the electron carrier to the electron acceptor, i.e., the electrons easily flow between the N-type semiconductor material and the first modification material, such that the film can have the good electron transmission performance, and the electrical property of the photoelectric device can be improved when the film is applied to the photoelectric device.

Description

Technical Field

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

[0002] Electroluminescent devices include OLED (Organic Light-Emitting Diode) and QLED (Quantum Dot Light Emitting Diodes). QLED has advantages such as high color saturation, wet-processability, and high stability, which has attracted more and more attention in the research of QLED. OLED has been widely used in the fields of display, lighting, and smart wear due to its good self-luminous characteristics, high contrast, fast response, and flexible display.

[0003] The electron transport layer is an important film layer in the electroluminescent device, which undertakes the function of transporting electrons to the light-emitting layer. However, due to the poor electron transport performance of the existing electron transport layer, the amount of electrons injected into the light-emitting layer is small, resulting in the problem of carrier imbalance in the light-emitting layer, and the electrical performance of the electroluminescent device is poor. Summary of the Invention

[0004] Based on this, the embodiments of the present application provide a thin film, a preparation method thereof, an optoelectronic device, and a display device.

[0005] In a first aspect, the embodiments of the present application provide a thin film, including a first modifying material and an N-type semiconductor material, and the first modifying material includes maleimide and / or maleimide derivatives.

[0006] In some embodiments, the maleimide derivatives include at least one of N-benzyl maleimide, N-phenyl maleimide, N-(1-pyrene) maleimide, 9-maleimide acridine, N-hydroxysuccinimide ester of 3-maleimide propionic acid, N-(4-nitrophenyl) maleimide, N-(4-fluorophenyl) maleimide, 3,4-dibromo maleimide, 6-maleimide hexanoic acid, and 4-maleimide butyric acid; and / or

[0007] The thickness of the thin film is 10 nm to 60 nm.

[0008] In some embodiments, the thin film has a single-layer structure, and the thin film includes a mixture of a first modifying material and an N-type semiconductor material, wherein the mass ratio of the first modifying material to the N-type semiconductor material is (1 - 5):30;

[0009] Alternatively, the thin film is a single-layer structure, and the thin film comprises a mixture of a first modifying material, an N-type semiconductor material, and a second modifying material, wherein the mass ratio of the first modifying material, the N-type semiconductor material, and the second modifying material is (1 - 5):30:(1 - 5), and the second modifying material comprises fulvalene and / or a fulvalene derivative.

[0010] In some embodiments, the fulvalene derivative comprises at least one of tetrathiafulvalene, dimethyltetrathiafulvalene, formyltetrathiafulvalene, 4,4'-diphenyltetrathiafulvalene, tetramethyltetraselenofulvalene, bis(trimethylenedithio)tetrathiafulvalene, and tetrakis(methylthio)tetrathiafulvalene.

[0011] In some embodiments, the thin film comprises a first sub-layer and a second sub-layer which are stacked, the first sub-layer comprises the N-type semiconductor material, the second sub-layer comprises the first modifying material, and the thickness ratio of the second sub-layer to the first sub-layer is (1 - 5):30;

[0012] Alternatively, the thin film comprises a third sub-layer, a first sub-layer, and a second sub-layer which are stacked in sequence, the first sub-layer comprises the N-type semiconductor material, the second sub-layer comprises the first modifying material, the material of the third sub-layer comprises a second modifying material, the second modifying material comprises fulvalene and / or a fulvalene derivative, and the thickness ratio of the third sub-layer, the first sub-layer, and the third sub-layer is (1 - 5):30:(1 - 5).

[0013] In some embodiments, the N-type semiconductor material is selected from at least one of metal oxides, doped metal oxides, group II-VI semiconductor materials, group III-V semiconductor materials, and group I-III-VI semiconductor materials; and / or

[0014] The metal oxide is selected from at least one of ZnO, BaO, TiO2, and SnO2; and / or

[0015] The metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2, and SnO2, and the doping element is selected from at least one of Al, Mg, Li, In, and Ga; and / or

[0016] The group II-VI semiconductor material is selected from at least one of ZnS, ZnSe, and CdS; and / or

[0017] The group III-V semiconductor material is selected from at least one of InP and GaP; and / or

[0018] The group I-III-VI semiconductor material is selected from at least one of CuInS and CuGaS.

[0019] Second aspect, an embodiment of the present application provides a method for preparing a thin film, including:

[0020] Providing a composite material solution, the composite material solution includes a first modifying material, an N-type semiconductor material, and a first solvent, and the first modifying material includes maleimide and / or maleimide derivatives;

[0021] Depositing the composite material solution to obtain a thin film.

[0022] In some embodiments, in the composite material solution, the concentration of the first modifying material is 1 mg / ml to 5 mg / ml, and the concentration of the N-type semiconductor material is 10 mg / ml to 50 mg / ml; and / or

[0023] The first solvent in the composite material solution includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran, dinitrotoluene, ethanol, and acetone; and / or

[0024] The depositing the composite material solution to obtain a thin film includes: depositing the composite material solution to obtain a first wet film layer, and performing a first annealing treatment on the first wet film layer to obtain a thin film, wherein the temperature of the first annealing treatment is 80°C to 120°C, and the time of the first annealing treatment is 5 minutes to 10 minutes.

[0025] In some embodiments, the composite material solution further includes a second modifying material, the second modifying material includes fulvalene and / or fulvalene derivatives, and the concentration of the second modifying material in the composite material solution is 1 mg / ml to 5 mg / ml.

[0026] Third aspect, an embodiment of the present application provides a method for preparing a thin film, including:

[0027] Providing a first modifying material solution, the first modifying material solution includes a first modifying material and a third solvent, the first modifying material includes maleimide and / or maleimide derivatives, depositing the first modifying material solution to obtain a second wet film layer, and performing an annealing treatment on the second wet film layer to obtain a second sublayer;

[0028] Providing an N-type semiconductor material solution, the N-type semiconductor material solution includes an N-type semiconductor material and a second solvent, depositing the N-type semiconductor material solution to obtain a first sublayer, and forming a thin film, the thin film includes a second sublayer and a first sublayer stacked.

[0029] In some embodiments, in the N-type semiconductor material solution, the concentration of the N-type semiconductor material is 10 mg / ml to 50 mg / ml; and / or

[0030] The second solvent in the N-type semiconductor material solution includes at least one of methanol, ethanol, isobutanol, isopropanol, and butanol; and / or

[0031] In the first modifying material solution, the concentration of the first modifying material is 1 mg / ml to 5 mg / ml; and / or

[0032] The third solvent in the first modifying material solution includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran, dinitrotoluene, ethanol, and acetone; and / or

[0033] Depositing the N-type semiconductor material solution to obtain the first sub-layer includes: depositing the N-type semiconductor material solution to obtain a third wet film layer, performing a second annealing treatment on the third wet film layer to obtain the first sub-layer, wherein the temperature of the second annealing treatment is 80°C to 120°C, and the time of the second annealing treatment is 5 minutes to 10 minutes; and / or

[0034] The thickness ratio of the second sub-layer to the first sub-layer is (1 - 5):30.

[0035] In some embodiments, the method for preparing the thin film further includes:

[0036] Providing a second modifying material solution, the second modifying material solution includes a second modifying material and a fourth solvent, the second modifying material includes fulvalene and / or fulvalene derivatives, depositing the second modifying material solution to obtain a fourth wet film layer, and performing a third annealing treatment on the fourth wet film layer to obtain a third sub-layer;

[0037] The thin film includes a second sub-layer, a first sub-layer, and a third sub-layer that are sequentially stacked.

[0038] In some embodiments, in the second modifying material solution, the concentration of the second modifying material is 1 mg / ml to 5 mg / ml; and / or

[0039] The fourth solvent in the second modifying material solution includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran, dinitrotoluene, ethanol, and acetone; and / or

[0040] The thickness ratio of the third sub-layer, the first sub-layer, and the second sub-layer is (1 - 5):30:(1 - 5).

[0041] Fourth aspect, an embodiment of the present application provides an optoelectronic device, including an anode and a cathode disposed opposite to each other, and N light-emitting unit layers and N-1 charge generation layers disposed between the anode and the cathode, with one charge generation layer disposed between every two adjacent light-emitting unit layers, where N is an integer greater than or equal to 2;

[0042] Each light-emitting unit layer includes a stacked light-emitting layer and an electron transport layer, where the electron transport layer is located on the side of the light-emitting layer close to the cathode;

[0043] Wherein, at least one electron transport layer located between the charge generation layer and the light-emitting layer includes the thin film as described above or a thin film prepared by the preparation method of the thin film as described above.

[0044] In some embodiments, the optoelectronic device further includes a stacked hole injection layer and a hole transport layer, the hole injection layer and the hole transport layer are located between the anode and the light-emitting unit layer closest to the anode, and the hole transport layer is located on the side of the hole injection layer close to the cathode; and / or

[0045] Each charge generation layer includes a stacked hole generation layer and an electron generation layer, and in each charge generation layer, the hole generation layer is disposed on the side of the electron generation layer close to the cathode.

[0046] In some embodiments, the anode and the cathode independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal single electrode or an alloy electrode respectively. The material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide. The composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS or ZnS / Al / ZnS. The material of the metal single electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg and Ba; and / or

[0047] The materials of each light-emitting layer independently include one or more of an organic light-emitting material and a quantum dot light-emitting material. The organic light-emitting 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, diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent material, TTPX fluorescent material, TBRb fluorescent material, DBP fluorescent material, delayed fluorescence material, TTA material, thermally activated delayed material, polymer containing B-N covalent bond, hybrid local charge transfer excited state material, exciplex luminescent material, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives;The quantum dot light-emitting material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots are each independently selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds include one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The 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 one or more of CuInS2, CuInSe2, and AgInS2. 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 AMX3, where A is Cs; + ion, M is a divalent metal cation, including Pb 2+ , Sn 2+ , Cu 2+ , Ni2+ 、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, including Cl - Br - ,I - One or more of; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, wherein B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including 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, including Cl - Br - ,I - One or more of; and / or

[0048] The materials of the hole transport layer include one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(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(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiro-NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-)phenylene vinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or

[0049] The materials of the hole injection layer and the materials of each hole generation layer independently include one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, PEDOT, PEDOT:PSS, derivatives of PEDOT:PSS doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0050] In a fifth aspect, an embodiment of the present application provides a display device, including the optoelectronic device as described above.

[0051] The thin film provided by the embodiment of the present application contains a first modification material, and the first modification material includes maleimide and / or maleimide derivatives. Since the electron density in the first modification material (maleimide and / or maleimide derivatives) is small (electron-deficient), it can act as an electron acceptor, while the N-type semiconductor material has good electrical conductivity and can act as an electron carrier. Since electrons are easily transferred from the electron carrier to the electron acceptor, that is to say, electrons are easy to flow between the N-type semiconductor material and the first modification material, so that the thin film can have good electron transport performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] 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.

[0053] Figure 1 FIG. 1 is a first schematic structural diagram of the thin film provided by the embodiment of the present application.

[0054] Figure 2 FIG. 2 is a second schematic structural diagram of the thin film provided by the embodiment of the present application.

[0055] Figure 3 FIG. 3 is a third schematic structural diagram of the thin film provided by the embodiment of the present application.

[0056] Figure 4 FIG. 4 is a first flowchart of the preparation method of the thin film provided by the embodiment of the present application.

[0057] Figure 5 FIG. 5 is a second flowchart of the preparation method of the thin film provided by the embodiment of the present application.

[0058] Figure 6 FIG. 6 is a schematic structural diagram of the optoelectronic device provided by the embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application.

[0060] In this application, "and / or" describes the relationship between associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone. Here, A and B can be singular or plural.

[0061] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single items (pieces) or plural items (pieces). 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, a + c, b + c, or a + b + c, where a, b, and c can be single or multiple respectively.

[0062] In this application, forming another layer "on" a certain layer, the so-called "on" is a broad concept, which can mean that the formed another layer is adjacent to a certain layer, or there are other spacer structure layers between the another layer and a certain layer. For example, forming a second electrode "on" the first carrier functional layer, the so-called "on" can mean that the formed second electrode is adjacent to the first carrier functional layer, or there are other spacer structure layers between the second electrode and the first carrier functional layer, such as a light-emitting layer.

[0063] "Parts by weight" refers to the basic measurement unit representing the mass ratio relationship of multiple components. 1 part can represent any unit mass, such as 1 g, 1 Kg, or it can also represent 2 g, 2 Kg, etc. Suppose we say that the parts by weight of component A is a parts and the parts by weight of component B is b parts, then it represents the mass ratio a:b of component A and component B. Or, it represents that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiple factor). It should not be misunderstood that, different from the number of parts by weight, the sum of the parts by weight of all components is not limited to 100 parts.

[0064] The various embodiments of this application can 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 the 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 the individual numbers within that range, such as 1, 2, 3, 4, 5, and 6. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0065] Please refer to Figure 1, an embodiment of the present application provides a thin film 61, which includes a first modifying material and an N-type semiconductor material, and the first modifying material includes maleimide and / or maleimide derivatives.

[0066] Exemplarily, the maleimide derivatives include at least one of N-benzyl maleimide, N-phenyl maleimide, N-(1-pyrene) maleimide, 9-maleimide acridine, N-hydroxysuccinimide ester of 3-maleimide propionic acid, N-(4-nitrophenyl) maleimide, N-(4-fluorophenyl) maleimide, 3,4-dibromo maleimide, 6-maleimide hexanoic acid, 4-maleimide butyric acid.

[0067] Exemplarily, the thickness of the thin film 61 is 10 nm to 60 nm, such as 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 60 nm, etc.

[0068] Please refer to Figure 1 , the thin film 61 may be a single-layer structure, and the thin film includes a mixture of a first modifying material and an N-type semiconductor material, wherein the mass ratio of the first modifying material to the N-type semiconductor material is (1-5):30, such as 1:30, 2:30, 3:30, 4:30, 5:30, etc.

[0069] It can be understood that when the material of the thin film 61 is a composite material, it means that the first modifying material and the N-type semiconductor material are mixed with each other. At this time, since the electron density in the first modifying material (maleimide and / or maleimide derivatives) is small (electron-deficient), it can act as an electron acceptor, while the N-type semiconductor material has good conductivity and can act as an electron carrier. Since electrons are easily transferred from the electron carrier to the electron acceptor, that is to say, electrons are easy to flow between the N-type semiconductor material and the first modifying material, so that the thin film 61 can have good electron transport performance.

[0070] Please refer to Figure 1 , the thin film may be a single-layer structure, and the thin film includes a mixture of a first modifying material, an N-type semiconductor material and a second modifying material, and the second modifying material includes fulvalene and / or fulvalene derivatives, wherein the mass ratio of the first modifying material, the N-type semiconductor material, and the second modifying material is (1-5):30:(1-5), such as 1:30:1, 2:30:2, 3:30:3, 4:30:4, 5:30:5, 1:30:3, 2:30:5, 2:30:4, etc.

[0071] Exemplarily, the fulvalene derivative includes at least one of tetrathiafulvalene, dimethyltetrathiafulvalene, formyltetrathiafulvalene, 4,4'-diphenyltetrathiafulvalene, tetramethyltetraselenafulvalene, bis(trimethylenedithio)tetrathiafulvalene, and tetrakis(methylthio)tetrathiafulvalene.

[0072] It can be understood that when the composite material further includes a second modifying material (fulvalene and / or fulvalene derivative), it means that the composite material contains the first modifying material (maleimide and / or maleimide derivative), the N-type semiconductor material, and the second modifying material (fulvalene and / or fulvalene derivative) at the same time. Since the electron density in the second modifying material (fulvalene and / or fulvalene derivative) is relatively large (electron-rich), and the electron density in the first modifying material (maleimide and / or maleimide derivative) is relatively small (electron-deficient), electrons are likely to transfer from the second modifying material (fulvalene and / or fulvalene derivative) to the first modifying material (maleimide and / or maleimide derivative). That is to say, electrons can easily flow between the second modifying material and the first modifying material, thereby improving the electron transport performance of the thin film 61.

[0073] It should be noted that when the composite material further includes a second modifying material (fulvalene and / or fulvalene derivative), since both fulvalene and fulvalene derivatives can combine with the metal elements on the surface of the N-type semiconductor material to form stable chemical bonds, the N-type semiconductor materials in the thin film 61 can be connected to form a stable structure, thereby improving the density of the thin film 61 and enhancing the solvent resistance of the thin film 61, and further improving or eliminating the crack phenomenon of the thin film 61.

[0074] Please refer to Figure 2 , the thin film 61 may include a first sub-layer 611 and a second sub-layer 612 arranged in a stacked manner. The first sub-layer 611 includes the N-type semiconductor material, and the material of the second sub-layer 612 includes the first modifying material. The thickness ratio of the second sub-layer 612 to the first sub-layer 611 is (1 - 5):30, such as 1:30, 2:30, 3:30, 4:30, 5:30, etc.

[0075] It can be understood that when the thin film 61 includes a first sub-layer 611 and a second sub-layer 612 arranged in a stacked manner, it means that the first modifying material and the N-type semiconductor material respectively form film layers independently. At this time, at the interface between the second sub-layer 612 and the first sub-layer 611, since the electron density in the second sub-layer 612 (maleimide and / or maleimide derivative) is relatively small (electron-deficient), it can act as an electron acceptor, while the first sub-layer 611 has good electrical conductivity and can act as an electron carrier. Since electrons are easily transferred from the electron carrier to the electron acceptor, that is to say, electrons are easy to flow between the first sub-layer 611 and the second sub-layer 612, so that the thin film 61 can have good electron transport performance.

[0076] Please refer to Figure 3 , the thin film 61 may include a third sub-layer 613, a first sub-layer 611 and a second sub-layer 612 arranged in a stacked manner in sequence. The first sub-layer 611 includes the N-type semiconductor material, the second sub-layer 612 includes the first modifying material, the material of the third sub-layer 613 includes a second modifying material, the second modifying material includes fulvalene and / or fulvalene derivative, and the thickness ratio of the third sub-layer 613, the first sub-layer 611 and the second sub-layer 612 is (1-5):30:(1-5), such as 1:30:1, 2:30:2, 3:30:3, 4:30:4, 5:30:5, 1:30:3, 2:30:5, 2:30:4, etc.

[0077] It can be understood that when the thin film 61 includes a second sub-layer 612, a first sub-layer 611 and a third sub-layer 613 arranged in a stacked manner in sequence, since the electron density in the material (maleimide and / or maleimide derivative) of the second sub-layer 612 is relatively small (electron-deficient), and the electron density in the material (fulvalene and / or fulvalene derivative) of the third sub-layer 613 is relatively large (electron-rich), electrons are easy to flow in the direction from the third sub-layer 613 to the second sub-layer 612, so that the electron transport performance of the thin film 61 can be improved; and, since the material of the third sub-layer 613 includes fulvalene and / or fulvalene derivative, and both fulvalene and fulvalene derivative can form stable chemical bonds with the metal elements on the surface of the N-type semiconductor material, the N-type semiconductor materials in the first sub-layer 611 can be connected to form a stable structure, so that the density of the thin film 61 can be improved, the solvent resistance of the thin film 61 can be improved, and the crack phenomenon of the thin film 61 can be improved or eliminated.

[0078] Exemplarily, the N-type semiconductor material includes at least one of metal oxides, doped metal oxides, group II-VI semiconductor materials, group III-V semiconductor materials, and group I-III-VI semiconductor materials; the metal oxide is selected from at least one of ZnO, BaO, TiO2, and SnO2; the metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2, and SnO2, and the doping element is selected from at least one of Al, Mg, Li, In, and Ga; the group II-VI semiconductor material is selected from at least one of ZnS, ZnSe, and CdS; the group III-V semiconductor material is selected from at least one of InP and GaP; the group I-III-VI semiconductor material is selected from at least one of CuInS and CuGaS.

[0079] The thin film 61 provided in the embodiment of the present application contains a first modifying material, and the first modifying material includes maleimide and / or maleimide derivatives. Since the electron density in the first modifying material (maleimide and / or maleimide derivatives) is small (electron-deficient), it can act as an electron acceptor, while the N-type semiconductor material has good conductivity and can act as an electron carrier. Since electrons are easily transferred from the electron carrier to the electron acceptor, that is to say, electrons are easy to flow between the N-type semiconductor material and the first modifying material, so that the thin film 61 can have good electron transport performance, and when the thin film 61 is applied to optoelectronic devices, the electrical performance of the optoelectronic devices can be improved.

[0080] Please refer to Figure 4 , and at the same time combine Figure 1 , the embodiment of the present application provides a method for preparing a thin film, including:

[0081] S110, providing a composite material solution, the composite material solution includes a first modifying material, an N-type semiconductor material, and a first solvent, and the first modifying material includes maleimide and / or maleimide derivatives.

[0082] S120, depositing the composite material solution to obtain the thin film 61.

[0083] Exemplarily, in the composite material solution, the concentration of the first modifying material is 1 mg / ml to 5 mg / ml (such as 1 mg / ml, 2 mg / ml, 3 mg / ml, 4 mg / ml, 5 mg / ml, etc.), and the concentration of the N-type semiconductor material is 10 mg / ml to 50 mg / ml (such as 10 mg / ml, 15 mg / ml, 20 mg / ml, 25 mg / ml, 30 mg / ml, 35 mg / ml, 40 mg / ml, 45 mg / ml, 50 mg / ml, etc.).

[0084] It should be noted that the reason for setting the concentration of the N-type semiconductor material in the composite material solution to 10 mg / ml to 50 mg / ml is as follows: when the concentration of the N-type semiconductor material is greater than 50 mg / ml, due to the too high concentration, the collision of the N-type semiconductor material in the solution will be accelerated, and the agglomeration of the N-type semiconductor material is more likely to occur. When the concentration of the N-type semiconductor material is less than 10 mg / ml, due to the low concentration, the thickness of the prepared thin film 61 will be too thin and the film thickness will be uneven.

[0085] Exemplarily, the first solvent in the composite material solution includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMEAA), N,N-dimethylpropionamide (DMPA), 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran (THF), dinitrotoluene, ethanol, and acetone.

[0086] Exemplarily, depositing the composite material solution to obtain the thin film 61 includes: depositing the composite material solution to obtain a first wet film layer, and performing a first annealing treatment on the first wet film layer to obtain the thin film 61, wherein the temperature of the first annealing treatment is 80°C to 120°C (such as 80°C, 90°C, 100°C, 110°C, 120°C, etc.), and the time of the first annealing treatment is 5 minutes to 10 minutes (such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.).

[0087] It should be noted that the reason for selecting the heating temperature to be 80°C to 120°C is as follows: when the heating temperature is higher than 120°C, the ligands on the surface of the N-type semiconductor material (such as zinc oxide nanoparticles) will be inactivated, increasing the steric hindrance and reducing the electron transport efficiency. When the heating temperature is lower than 80°C, the solvent in the thin film 61 cannot be completely removed, and when other functional thin films 61 are prepared on the thin film 61 later, the material of the composite thin film 61 will be washed away.

[0088] Exemplarily, the composite material solution further includes a second modification material, the second modification material includes fulvalene and / or fulvalene derivatives, and the concentration of the second modification material in the composite material solution is 1 mg / ml to 5 mg / ml (such as 1 mg / ml, 2 mg / ml, 3 mg / ml, 4 mg / ml, 5 mg / ml, etc.).

[0089] Please refer to Figure 5 and in combination with Figure 2 An embodiment of the present application provides a method for preparing a thin film, including:

[0090] S210, Provide a first modifying material solution, the first modifying material solution includes a first modifying material and a third solvent, the first modifying material includes maleimide and / or maleimide derivatives, deposit the first modifying material solution to obtain a second sub-layer 612.

[0091] Exemplarily, in the first modifying material solution, the concentration of the first modifying material is 1 mg / ml to 5 mg / ml, such as 1 mg / ml, 2 mg / ml, 3 mg / ml, 4 mg / ml, 5 mg / ml, etc.

[0092] Exemplarily, the third solvent in the first modifying material solution includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMEAA), N,N-dimethylpropanamide (DMPA), 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran (THF), dinitrotoluene, ethanol, and acetone.

[0093] Exemplarily, the thickness ratio of the second sub-layer 612 to the first sub-layer 611 is (1 - 5):30, such as 1:30, 2:30, 3:30, 4:30, 5:30, etc.

[0094] Exemplarily, depositing the first modifying material solution to obtain the second sub-layer 612 includes: depositing the first modifying material solution to obtain a second wet film layer, annealing the second wet film layer to obtain the second sub-layer 612, the annealing temperature is 80°C to 120°C (such as 80°C, 90°C, 100°C, 110°C, 120°C, etc.), and the annealing time is 5 minutes to 10 minutes (such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.).

[0095] S220, Please combine Figure 2 , Provide an N-type semiconductor material solution, the N-type semiconductor material solution includes an N-type semiconductor material and a second solvent, deposit the N-type semiconductor material solution to obtain a first sub-layer 611, and form a thin film 61, the thin film 61 includes a second sub-layer 612 and a first sub-layer 611 arranged in a stacked manner.

[0096] It should be noted that the order of S210 and S220 in the embodiments of the present application is not limited, that is, the second sub-layer 612 can be prepared first or the first sub-layer 611 can be prepared first; in some embodiments, the second sub-layer 612 is prepared first and then the first sub-layer 611 is prepared. At this time, deposit the N-type semiconductor material solution on the second sub-layer 612 to obtain the first sub-layer 611.

[0097] Exemplarily, in the N-type semiconductor material solution, the concentration of the N-type semiconductor material is 10 mg / ml to 50 mg / ml, such as 10 mg / ml, 15 mg / ml, 20 mg / ml, 25 mg / ml, 30 mg / ml, 35 mg / ml, 40 mg / ml, 45 mg / ml, 50 mg / ml, etc.

[0098] It should be noted that the reason for setting the concentration of the N-type semiconductor material in the N-type semiconductor material solution to 10 mg / ml to 50 mg / ml is as follows: when the concentration of the N-type semiconductor material is greater than 50 mg / ml, due to the too high concentration, the collision of the N-type semiconductor material in the solution will be accelerated, and the phenomenon of agglomeration of the N-type semiconductor material is more likely to occur. When the concentration of the N-type semiconductor material is less than 10 mg / ml, due to the low concentration, the thickness of the obtained first sub-layer 611 will be too thin and the film thickness will be uneven.

[0099] Exemplarily, the second solvent in the N-type semiconductor material solution includes at least one of methanol, ethanol, isobutanol, isopropanol, and butanol.

[0100] Exemplarily, depositing the N-type semiconductor material solution to obtain the first sub-layer 611 includes: depositing the N-type semiconductor material solution on the second sub-layer 612 to obtain a third wet film layer, and performing a second annealing treatment on the third wet film layer to obtain the first sub-layer 611, wherein the temperature of the second annealing treatment is 80 °C to 120 °C (such as 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, etc.), and the time of the second annealing treatment is 5 minutes to 10 minutes (such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.).

[0101] It should be noted that the reason for selecting the heating temperature to be 80 °C to 120 °C is as follows: when the heating temperature is higher than 120 °C, the ligands on the surface of the N-type semiconductor material (such as zinc oxide nanoparticles) will be inactivated, increasing the steric hindrance and reducing the electron transport efficiency. When the heating temperature is lower than 80 °C, the solvent in the first sub-layer 611 cannot be completely removed, and the material of the first sub-layer 611 will be washed away when preparing other functional thin films 61 on the first sub-layer 611 subsequently.

[0102] Exemplarily, please refer to Figure 3 , the method for preparing the thin film may further include:

[0103] Providing a second modifying material solution, the second modifying material solution includes a second modifying material and a fourth solvent, the second modifying material includes fulvalene and / or fulvalene derivatives, and depositing the second modifying material solution on the first sub-layer 611 to obtain a third sub-layer 613;

[0104] The thin film 61 includes a second sub-layer 612, a first sub-layer 611, and a third sub-layer 613 that are sequentially stacked.

[0105] Please refer to Figure 3 , it can be understood that in the thin film 61, the second sub-layer 612 and the third sub-layer 613 are respectively disposed on both sides of the first sub-layer 611. In the embodiments of the present application, the preparation sequence of the second sub-layer 612, the first sub-layer 611, and the third sub-layer 613 is not limited. That is, the thin film 61 can be prepared in the order of sequentially fabricating the second sub-layer 612, the first sub-layer 611, and the third sub-layer 613, or in the order of sequentially fabricating the third sub-layer 613, the first sub-layer 611, and the second sub-layer 612.

[0106] In some embodiments, the thin film 61 is prepared in the order of sequentially fabricating the second sub-layer 612, the first sub-layer 611, and the third sub-layer 613. At this time, the second modifying material solution is deposited on the first sub-layer 611 to obtain the third sub-layer 613.

[0107] Exemplarily, in the second modifying material solution, the concentration of the second modifying material is 1 mg / ml to 5 mg / ml, such as 1 mg / ml, 2 mg / ml, 3 mg / ml, 4 mg / ml, 5 mg / ml, etc.

[0108] Exemplarily, depositing the second modifying material solution on the first sub-layer 611 to obtain the third sub-layer 613 includes: depositing the second modifying material solution on the first sub-layer 611 to obtain a fourth wet film layer, and performing a third annealing treatment on the fourth wet film layer to obtain the third sub-layer 613, where the temperature of the third annealing treatment is 80°C to 120°C (such as 80°C, 90°C, 100°C, 110°C, 120°C, etc.), and the time of the third annealing treatment is 5 minutes to 10 minutes (such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.).

[0109] Exemplarily, the fourth solvent in the second modifying material solution includes at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMEAA), N,N-dimethylpropanamide (DMPA), 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran (THF), dinitrotoluene, ethanol, and acetone.

[0110] Exemplarily, the thickness ratio of the third sub-layer 613, the first sub-layer 611, and the second sub-layer 612 is (1 - 5):30:(1 - 5), such as 1:30:1, 2:30:2, 3:30:3, 4:30:4, 5:30:5, 1:30:3, 2:30:5, 2:30:4, etc.

[0111] Please refer toFigure 6 Meanwhile, in combination with Figures 1 to 3 An embodiment of the present application further provides an optoelectronic device 100, which includes an anode 21 and a cathode 22 disposed opposite to each other, and N light-emitting unit layers 30 and N - 1 charge generation layers 40 disposed between the anode 21 and the cathode 22. One charge generation layer 40 is disposed between every two adjacent light-emitting unit layers 30, where N is an integer greater than or equal to 2.

[0112] Each light-emitting unit layer 30 includes a stacked light-emitting layer 31 and an electron transport layer 32, where the electron transport layer 32 is located on the side of the light-emitting layer 31 close to the cathode 22.

[0113] Among them, at least one electron transport layer 32 located between the charge generation layer 40 and the light-emitting layer 31 includes the thin film 61 in any of the above embodiments or the thin film 61 prepared by the preparation method of the thin film 61 in any of the above embodiments.

[0114] Please refer to Figure 6 , the optoelectronic device 100 further includes a stacked hole injection layer 50 and a hole transport layer 70. The hole injection layer 50 and the hole transport layer 70 are located between the anode 21 and the light-emitting unit layer 30 closest to the anode 21, and the hole transport layer 70 is located on the side of the hole injection layer 50 close to the cathode 22.

[0115] Each of the charge generation layers 40 includes a stacked hole generation layer 42 and an electron generation layer 41. In each of the charge generation layers 40, the hole generation layer 42 is disposed on the side of the electron generation layer 41 close to the cathode 22.

[0116] It should be noted that in existing multi-light-emitting layer devices (stacked devices), the charge separation efficiency of the charge generation layer is usually low, resulting in carrier imbalance and low light-emitting efficiency inside the multi-light-emitting layer device (stacked device). In the embodiment of the present application, by setting at least one electron transport layer 32 located between the charge generation layer 40 and the light-emitting layer 31 to include the thin film 61, since the thin film 61 has good electron transport performance, it can promote the separation of electrons and holes in the charge generation layer 30, improve the charge separation efficiency, thereby promoting the carrier balance inside the multi-light-emitting layer device (stacked device) and improving the light-emitting efficiency of the multi-light-emitting layer device (stacked device).

[0117] Exemplarily, the anode 21 and the cathode 22 each independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal element electrode, or an alloy electrode. The material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the metal element electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba.

[0118] Exemplarily, the materials of each light-emitting layer 31 independently include one or more of an organic light-emitting material and a quantum dot light-emitting material. The organic light-emitting 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, a diarylanthracene 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 thermally activated delayed material, a polymer containing a B-N covalent bond, a hybrid locally charge-transfer excited state material, an exciplex light-emitting material, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives;The quantum dot luminescent material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots are each independently selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds include one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The 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 one or more of CuInS2, CuInSe2, and AgInS2. 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 AMX3, where A is Cs; + ion, M is a divalent metal cation, including Pb 2+ , Sn 2+ , Cu 2+ , Ni2+ 、Cd 2+ 、Cr 2+ 、Mn 2+ 、Co 2+ 、Fe 2+ 、Ge 2+ 、Yb 2+ 、Eu 2+ one or more of Cd, Cr, Mn, Co, Fe, Ge, Yb, Eu, X is a halogen anion including Cl - 、Br - 、I - one or more of Br, I; the structural general formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation including 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 Sn, Cu, Ni, Cd, Cr, Mn, Co, Fe, Ge, Yb, Eu, X is a halogen anion including Cl - 、Br - 、I - one or more of Br, I.

[0119] Exemplarily, the material of the hole transport layer 70 includes one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(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(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiro-NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetra[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-)phenylene vinylene, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO.

[0120] Exemplarily, the material of the hole injection layer 50 and the material of each hole generation layer 42 independently include one or more of 2,3,6,7,10,11 - hexacyano - 1,4,5,8,9,12 - hexaazatriphenylene, PEDOT, PEDOT:PSS, a derivative of PEDOT:PSS doped with s - MoO3, 4,4',4' - tris(N - 3 - methylphenyl - N - phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0121] Please refer to Figure 3 , when the thin film 61 includes a second sub - layer 612, a first sub - layer 611, and a third sub - layer 613 which are sequentially stacked, the second sub - layer 612, the first sub - layer 611, and the third sub - layer 613 are sequentially stacked in the direction from the anode 21 to the cathode 22. It should be noted that, due to the relatively small electron density (electron - deficient) in the material (maleimide and / or maleimide derivative) of the second sub - layer 612 and the relatively large electron density (electron - rich) in the material (fulvalene and / or fulvalene derivative) of the third sub - layer 613, electrons are likely to flow in the direction from the third sub - layer 613 to the second sub - layer 612, thereby improving the electron transport performance of the thin film 61. When the thin film 61 is adjacent to the charge generation layer 30, due to the strong electron transport ability of the thin film 61, the separation of electrons and holes in the charge generation layer 30 can be promoted, the charge separation efficiency can be improved, and further the carrier balance inside the multi - emission layer device (stacked device) can be promoted, and the luminescence efficiency of the multi - emission layer device (stacked device) can be improved.

[0122] In some embodiments, the material of one electron transport layer 32 closest to the cathode 22 may include at least one of metal oxides, doped metal oxides, II - VI group semiconductor materials, III - V group semiconductor materials, and I - III - VI group semiconductor materials; the metal oxide is selected from at least one of ZnO, BaO, TiO2, and SnO2; the metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2, and SnO2, and the doping element is selected from at least one of Al, Mg, Li, In, and Ga; the II - VI semiconductor group material is selected from at least one of ZnS, ZnSe, and CdS; the III - V semiconductor group material is selected from at least one of InP and GaP; the I - III - VI group semiconductor material is selected from at least one of CuInS and CuGaS.

[0123] Exemplarily, the material of the electron generation layer 31 (CGL - N) includes one or more of phosphomolybdic acid (PMA), molybdenum oxide (MoO3), phosphotungstic acid, and tungsten trioxide (WO3).

[0124] Exemplarily, the thickness of each of the anode 21 and the cathode 22 is 10 nm - 120 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc.

[0125] Exemplarily, the thickness of the hole injection layer 50 is 10 nm - 50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0126] Exemplarily, the thickness of the hole transport layer 70 is 10 nm - 50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0127] Exemplarily, the thickness of the light-emitting layer 31 is 10 nm - 50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0128] Exemplarily, the thickness of the electron transport layer 32 is 10 nm - 50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0129] Exemplarily, the thickness of the charge generation layer 40 is 20 nm - 70 nm, such as 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, etc.

[0130] Exemplarily, the thickness of the electron generation layer 41 is 10 nm - 20 nm, such as 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, etc.

[0131] Exemplarily, the thickness of the hole generation layer 42 is 10 nm - 50 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, etc.

[0132] The embodiment of the present application further provides a display device, including the optoelectronic device in any of the above embodiments or the optoelectronic device prepared by the preparation method of the optoelectronic device in any of the above embodiments.

[0133] Exemplarily, the display device can be a terminal such as a television, a mobile phone, a tablet computer, a display, an advertising display screen, etc., and can also be a device with a display screen such as a game device, an augmented reality (AR) device, a virtual reality (VR) device, a data storage device, an audio playback device, a video playback device, a wearable device, etc., where the wearable device can be a smart bracelet, smart glasses, a smart watch, smart decoration, etc.

[0134] The thin film of the present application, its preparation method, and optoelectronic devices will be described in detail below in the form of specific embodiments.

[0135] Thin Film Example 1

[0136] A thin film, the preparation method of which includes:

[0137] Step 11: Provide a composite material solution, the composite material solution includes a first modifier (N-benzylmaleimide), an N-type semiconductor material (ZMO), and a first solvent (ethanol). The concentration of the first modifier (N-benzylmaleimide) is 3 mg / ml, and the concentration of the N-type semiconductor material (ZMO) is 30 mg / ml; wherein, N-benzylmaleimide is purchased from Aladdin Reagent (Shanghai) Co., Ltd., with a CAS number of 1631-26-1, a molecular formula of C 11 H9NO2, a molecular weight of 187.2, an MDL number of MFCD00014540, and a PubChem number of 74204;

[0138] Step 12: Deposit the composite material solution to obtain a first wet film layer, and perform annealing treatment on the first wet film layer (heat at 80 °C for 10 minutes) to obtain a thin film. The thickness of the thin film is 40 nm. The thin film is a single-layer structure and includes a mixture of a first modifier and an N-type semiconductor material. Among them, the mass ratio of the first modifier to the N-type semiconductor material is 3:30.

[0139] Thin Film Example 2

[0140] A thin film, the difference in its preparation method compared with Thin Film Example 1 is as follows:

[0141] In Step 11, in the composite material solution, the concentration of the first modifier (N-benzylmaleimide) is 1 mg / ml;

[0142] In Step 12, in the obtained thin film, the mass ratio of the first modifier to the N-type semiconductor material is 1:30.

[0143] Thin Film Example 3

[0144] A thin film, the difference in its preparation method compared with Thin Film Example 1 is as follows:

[0145] In Step 11, in the composite material solution, the concentration of the first modifier (N-benzylmaleimide) is 5 mg / ml;

[0146] In Step 12, in the obtained thin film, the mass ratio of the first modifier to the N-type semiconductor material is 5:30.

[0147] Thin Film Example 4

[0148] A thin film, the preparation method of which is different from that of Thin Film Example 1 in that:

[0149] In step 11, in the composite material solution, the first modifier is 4-maleimidobutyric acid, and the concentration of 4-maleimidobutyric acid is 4 mg / ml; among them, 4-maleimidobutyric acid is purchased from Aladdin Reagent (Shanghai) Co., Ltd., with a CAS number of 57078-98-5, a molecular formula of C8H9NO4, a molecular weight of 183.16, a Beilstein number of 1455876, an MDL number of MFCD00043139, and a PubChem number of 3404904.

[0150] Thin Film Example 5

[0151] A thin film, the preparation method of which is different from that of Thin Film Example 1 in that:

[0152] In step 11, the composite material solution includes a first modifier (N-benzylmaleimide), an N-type semiconductor material (ZMO), a first solvent (ethanol), and a second modifier (4,4'-diphenyltetrathiafulvalene). The concentration of the first modifier (N-benzylmaleimide) is 3 mg / ml, the concentration of the N-type semiconductor material (ZMO) is 30 mg / ml, and the concentration of the second modifier (4,4'-diphenyltetrathiafulvalene) is 3 mg / ml; among them, 4,4'-diphenyltetrathiafulvalene is purchased from Aladdin Reagent (Shanghai) Co., Ltd., with a CAS number of 5152-94-3, a molecular formula of C 18 H 12 S4, a molecular weight of 356.55, an MDL number of MFCD00075526, and a PubChem number of 16212369;

[0153] In step 12, the prepared thin film includes a mixture of a first modifier, an N-type semiconductor material, and a second modifier. Among them, the mass ratio of the first modifier, the N-type semiconductor material, and the second modifier is 3:30:3.

[0154] Thin Film Example 6

[0155] A thin film, the preparation method of which is different from that of Thin Film Example 5 in that:

[0156] In step 11, in the composite material solution, the concentration of the second modifier (4,4'-diphenyltetrathiafulvalene) is 1 mg / ml;

[0157] In step 12, in the prepared thin film, the mass ratio of the first modifier, the N-type semiconductor material, and the second modifier is 3:30:1.

[0158] Thin Film Example 7

[0159] A thin film, compared with the thin film in Example 5 in terms of its preparation method, is characterized in that:

[0160] In step 11, in the composite material solution, the concentration of the second modifying material (4,4'-diphenyltetrathiafulvalene) is 5 mg / ml;

[0161] In step 12, in the prepared thin film, the mass ratio of the first modifying material, the N-type semiconductor material and the second modifying material is 3:30:5.

[0162] Thin film Example 8

[0163] A thin film, its preparation method includes:

[0164] Step 21: Provide a first modifying material solution, the first modifying material solution includes a first modifying material (N-benzylmaleimide) and a third solvent (ethanol), deposit the first modifying material solution to obtain a third wet film layer, and perform annealing treatment on the third wet film layer (heating at 80 °C for 10 minutes) to obtain a second sub-layer (thickness 36.4 nm);

[0165] Step 22: Provide an N-type semiconductor material solution, the N-type semiconductor material solution includes an N-type semiconductor material (ZMO) and a second solvent (ethanol), deposit the N-type semiconductor material solution on the second sub-layer to obtain a second wet film layer, and perform annealing treatment on the second wet film layer (heating at 80 °C for 10 minutes) to obtain a first sub-layer (thickness 3.6 nm), and form a thin film, the thin film includes a second sub-layer and a first sub-layer arranged in a stacked manner, wherein the thickness ratio of the second sub-layer to the first sub-layer is 3:30.

[0166] Thin film Example 9

[0167] A thin film, its preparation method includes:

[0168] Step 21: Provide a first modifying material solution, the first modifying material solution includes a first modifying material (N-benzylmaleimide) and a third solvent (ethanol), deposit the first modifying material solution to obtain a third wet film layer, and perform annealing treatment on the third wet film layer (heating at 80 °C for 10 minutes) to obtain a second sub-layer (thickness 3.3 nm);

[0169] Step 22: Provide an N-type semiconductor material solution, the N-type semiconductor material solution includes an N-type semiconductor material (ZMO) and a second solvent (ethanol), deposit the N-type semiconductor material solution on the second sub-layer to obtain a second wet film layer, and perform annealing treatment on the second wet film layer (heating at 80 °C for 10 minutes) to obtain a first sub-layer (thickness 33.4 nm);

[0170] Step 23: Provide a second modifying material solution, which includes a second modifying material (4,4'-diphenyltetrathiafulvalene) and a third solvent (ethanol). Deposit the second modifying material solution on the first sub-layer to obtain a fourth wet film layer, and perform annealing treatment on the fourth wet film layer (heating at 80 °C for 10 minutes) to obtain a third sub-layer (with a thickness of 3.3 nm), thereby forming a thin film. The thin film includes a second sub-layer, a first sub-layer, and a third sub-layer that are sequentially stacked. Among them, the thickness ratio of the second sub-layer, the first sub-layer, and the third sub-layer is 3:30:3.

[0171] It can be seen that compared with Thin Film Example 8, the difference lies in that a third sub-layer is added above the first sub-layer in the thin film prepared in Thin Film Example 9.

[0172] Thin Film Example 10

[0173] A thin film, the difference in its preparation method compared with Thin Film Example 1 is as follows:

[0174] In Step 11, in the composite material solution, the concentration of the first modifying material (N-benzylmaleimide) is 10 mg / ml;

[0175] In Step 12, in the obtained thin film, the mass ratio of the first modifying material to the N-type semiconductor material is 10:30.

[0176] Thin Film Example 11

[0177] A thin film, the difference in its preparation method compared with Thin Film Example 5 is as follows:

[0178] In Step 11, in the composite material solution, the concentration of the second modifying material (4,4'-diphenyltetrathiafulvalene) is 10 mg / ml;

[0179] In Step 12, in the obtained thin film, the mass ratio of the first modifying material, the N-type semiconductor material, and the second modifying material is 3:30:10.

[0180] Thin Film Comparative Example 1

[0181] A method for preparing a thin film includes:

[0182] Provide an N-type semiconductor material solution, which includes an N-type semiconductor material (ZMO) and a solvent (ethanol). The concentration of the N-type semiconductor material (ZMO) is 30 mg / ml;

[0183] Deposit the N-type semiconductor material solution to obtain a wet film layer, and perform annealing treatment on the wet film layer (heating at 80 °C for 10 minutes) to obtain a thin film with a thickness of 40 nm.

[0184] Device Example 1

[0185] An optoelectronic device, the preparation method thereof comprising:

[0186] Step S1: Subject the washed anode (ITO) to UVO (ultraviolet ozone) treatment for 15 minutes, spin-coat PEDOT:PSS on the anode, and heat at 150 °C for 15 minutes to obtain a hole injection layer, the thickness of the hole injection layer being 30 nm;

[0187] Step S2: Spin-coat TFB on the hole injection layer, and heat at 150 °C for 15 minutes to obtain a hole transport layer, the thickness of the hole transport layer being 15 nm;

[0188] Step S3: Spin-coat core-shell structure quantum dots (ZnCdSe / ZnS, ZnCdSe as the core and ZnS as the shell) on the hole transport layer, and heat at 100 °C for 8 minutes to obtain a first light-emitting layer, the thickness of the first light-emitting layer being 30 nm;

[0189] Step S4: Form a thin film (first electron transport layer) on the first light-emitting layer by the method of Thin Film Example 1;

[0190] Step S5: Spin-coat PMA on the thin film to obtain an electron generation layer, and heat at 120 °C for 10 minutes, the thickness of the electron generation layer being 10 nm;

[0191] Step S6: Spin-coat TFB on the electron generation layer to obtain a hole generation layer, and heat at 150 °C for 10 minutes, the thickness of the hole generation layer being 15 nm;

[0192] Step S7: Spin-coat core-shell structure quantum dots (ZnCdSe / ZnS, ZnCdSe as the core and ZnS as the shell) on the hole generation layer, and heat at 100 °C for 8 minutes to obtain a second light-emitting layer, the thickness of the second light-emitting layer being 30 nm;

[0193] Step S8: Spin-coat ZMO nanoparticles on the second light-emitting layer, and heat at 80 °C for 10 minutes to obtain a second electron transport layer, the thickness of the second electron transport layer being 40 nm;

[0194] Step S9: Evaporate Ag on the second electron transport layer to obtain a cathode, the thickness of the cathode being 100 nm, thereby obtaining the optoelectronic device.

[0195] Device Example 2

[0196] An optoelectronic device, the difference in its preparation method compared with Device Example 1 being that:

[0197] In Step S4, a thin film (first electron transport layer) is formed on the first light-emitting layer by the method of Thin Film Example 2.

[0198] Device Example 3

[0199] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0200] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 3.

[0201] Device Example 4

[0202] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0203] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 4.

[0204] Device Example 5

[0205] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0206] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 5.

[0207] Device Example 6

[0208] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0209] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 6.

[0210] Device Example 7

[0211] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0212] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 7.

[0213] Device Example 8

[0214] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0215] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 8.

[0216] Device Example 9

[0217] An optoelectronic device, the difference in its preparation method compared with Device Example 1 lies in that:

[0218] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Example 9.

[0219] Device Embodiment 10

[0220] An optoelectronic device, the preparation method of which is different from that of Device Embodiment 1 in that:

[0221] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Embodiment 10.

[0222] Device Embodiment 11

[0223] An optoelectronic device, the preparation method of which is different from that of Device Embodiment 1 in that:

[0224] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Embodiment 11.

[0225] Device Comparative Example 1

[0226] An optoelectronic device, the preparation method of which is different from that of Device Embodiment 1 in that:

[0227] In step S4, a thin film (the first electron transport layer) is formed on the first light-emitting layer by using the method of Thin Film Comparative Example 1.

[0228] Performance Test:

[0229] (1) Electron mobility test of the thin film: Controlled by LabView, QE PRO and Keithley 2400 are used to build a set of QLED efficiency test systems. The current density-voltage curve of the single-carrier transport thin film device (EOD) is tested by this system. Through the current density-voltage curve, the space charge limited current (SCLC) region in the curve is obtained, and then according to the formula J = (9 / 8)ε r ε0μ e V 2 / d 3 the electron mobility is calculated, where J represents the current density, with the unit mAcm -2 ; ε r represents the relative dielectric constant, ε0 represents the vacuum dielectric constant; μ e represents the electron mobility, with the unit cm 2 V -1 s -1 ; V represents the driving voltage, with the unit V; d represents the film thickness, with the unit m. The test results are shown in Table 1.

[0230] Table 1

[0231]

[0232] It can be seen from Table 1 that the electron mobility of thin film embodiments 1-11 is greater than that of thin film comparison example 1. It is known that the difference between thin film embodiments 1-11 and thin film comparison example 1 is that the thin films prepared by thin film embodiments 1-11 of the present application all include ZMO (magnesium-doped zinc oxide) nanoparticles and a first modifying material (N-benzylmaleimide), while the thin film of thin film comparison example 1 is only composed of ZMO (magnesium-doped zinc oxide) nanoparticles. This shows that the present application can improve the electron mobility of the thin film by adding the first modifying material (N-benzylmaleimide) to the thin film, thereby making the thin film have better electron transmission performance.

[0233] (2) The optoelectronic devices prepared in device examples 1-11 and device comparison example 1 were tested. The FPD optical property measurement equipment was used to control the efficiency test system built by QE PRO spectrometer, Keithley2400, and Keithley6485 through LabView to measure parameters such as voltage, current, and brightness, and the luminous efficiency CE was calculated. The test results are shown in Table 2 below.

[0234] Table 2

[0235]

[0236]

[0237] Please refer to Table 2 above, it can be seen that the luminous efficiency of the optoelectronic devices of device embodiments 1-11 is greater than the luminous efficiency of the optoelectronic devices of device comparison example 1. It is known that the difference between device embodiments 1-11 and device comparison example 1 is only the material and manufacturing method of the thin film (first electron transport layer). The thin film (first electron transport layer) in device embodiments 1-11 of the present application includes ZMO (magnesium-doped zinc oxide) nanoparticles and a first modifying material (N-benzylmaleimide), while the thin film (first electron transport layer) of device comparison example 1 is only composed of ZMO (magnesium-doped zinc oxide) nanoparticles. This shows that after adding the first modifying material (N-benzylmaleimide) to the thin film (first electron transport layer), the electron transport performance of the thin film (first electron transport layer) can be improved, thereby improving the luminous efficiency of the optoelectronic device.

[0238] By comparing Device Examples 1-3 and Device Example 10, it can be seen that the luminous efficiency of the optoelectronic device in Device Example 10 is significantly lower than that of the optoelectronic devices in Device Examples 1-3. It is known that the only difference between Device Examples 1-3 and Device Example 10 is that in the thin film (the first electron transport layer) prepared in Device Examples 1-3, the mass ratio of the first modifying material to the N-type semiconductor material is (1-5):30, while in the thin film (the first electron transport layer) prepared in Device Example 10, the mass ratio of the first modifying material to the N-type semiconductor material is 10:30. It can be seen that this is due to the excessive content of the first modifying material (N-benzylmaleimide) in the thin film (the first electron transport layer) prepared in Device Example 10. It should be noted that when the content of the first modifying material (N-benzylmaleimide) in the thin film is excessive, since the conductivity of the first modifying material (N-benzylmaleimide) is poor, the conductivity of the thin film (the first electron transport layer) will be poor, thereby affecting the luminous efficiency of the optoelectronic device. In this application, by controlling the mass ratio of the first modifying material to the N-type semiconductor material to be (1-5):30, it is possible to ensure that the thin film (the first electron transport layer) has good conductivity, and thus ensure that the optoelectronic device has a high luminous efficiency.

[0239] By comparing Device Examples 5-7 and Device Example 11, it can be seen that the luminous efficiency of the optoelectronic device in Device Example 11 is significantly lower than that of the optoelectronic devices in Device Examples 5-7. It is known that the only difference between Device Examples 5-7 and Device Example 11 is that in the thin film (the first electron transport layer) prepared in Device Examples 5-7, the mass ratio of the second modifying material to the N-type semiconductor material is (1-5):30, while in the thin film (the first electron transport layer) prepared in Device Example 11, the mass ratio of the second modifying material to the N-type semiconductor material is 10:30. It can be seen that this is due to the excessive content of the second modifying material (4,4'-diphenyltetrathiafulvalene) in the thin film (the first electron transport layer) prepared in Device Example 11. It is known that the conductivity of the second modifying material (4,4'-diphenyltetrathiafulvalene) is good. However, when the content of the second modifying material (4,4'-diphenyltetrathiafulvalene) in the thin film (the first electron transport layer) is excessive, the electron concentration in the thin film (the first electron transport layer) will be too large, and the high-concentration electrons will accumulate at the interface between the hole transport layer and the light-emitting layer, resulting in the electrochemical corrosion and damage of the organic material in the hole transport layer, thereby causing the luminous efficiency of the optoelectronic device to decrease. In this application, by controlling the mass ratio of the second modifying material to the N-type semiconductor material to be (1-5):30, it is possible to ensure that the optoelectronic device has a high luminous efficiency.

[0240] 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 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, It includes a first modifying material and an N-type semiconductor material, and the first modifying material includes maleimide and / or maleimide derivatives.

2. The thin film according to claim 1, wherein The maleimide derivatives include at least one of N-benzyl maleimide, N-phenyl maleimide, N-(1-pyrene) maleimide, 9-maleimide acridine, N-hydroxysuccinimide ester of 3-maleimide propionic acid, N-(4-nitrophenyl) maleimide, N-(4-fluorophenyl) maleimide, 3,4-dibromo maleimide, 6-maleimide hexanoic acid, 4-maleimide butyric acid; and / or The thickness of the thin film is 10 nm to 60 nm.

3. The thin film according to claim 1, wherein The thin film has a single-layer structure, and the thin film includes a mixture of a first modifying material and an N-type semiconductor material, wherein the mass ratio of the first modifying material to the N-type semiconductor material is (1 - 5):30; Alternatively, the thin film has a single-layer structure, and the thin film includes a mixture of a first modifying material, an N-type semiconductor material, and a second modifying material, wherein the mass ratio of the first modifying material, the N-type semiconductor material, and the second modifying material is (1 - 5):30:(1 - 5), and the second modifying material includes fulvalene and / or fulvalene derivatives.

4. The thin film according to claim 3, wherein The fulvalene derivatives include at least one of tetrathiafulvalene, dimethyltetrathiafulvalene, formyltetrathiafulvalene, 4,4'-diphenyltetrathiafulvalene, tetramethyltetraselenofulvalene, bis(trimethylenedithio)tetrathiafulvalene, tetrakis(methylthio)tetrathiafulvalene.

5. The thin film according to claim 4, wherein, The thin film includes a first sub-layer and a second sub-layer arranged in a stacked manner, the first sub-layer includes the N-type semiconductor material, the second sub-layer includes the first modifying material, and the thickness ratio of the second sub-layer to the first sub-layer is (1 - 5):30; Alternatively, the thin film includes a third sub-layer, a first sub-layer, and a second sub-layer arranged in a stacked manner in sequence, the first sub-layer includes the N-type semiconductor material, the second sub-layer includes the first modifying material, the material of the third sub-layer includes a second modifying material, the second modifying material includes fulvalene and / or fulvalene derivatives, and the thickness ratio of the third sub-layer, the first sub-layer, and the third sub-layer is (1 - 5):30:(1 - 5).

6. The thin film according to any one of claims 1-5, characterized in that, The N-type semiconductor material is selected from at least one of metal oxides, doped metal oxides, group II-VI semiconductor materials, group III-V semiconductor materials, and group I-III-VI semiconductor materials; and / or The metal oxides are selected from at least one of ZnO, BaO, TiO2, SnO2; and / or The metal oxide in the doped metal oxide is selected from at least one of ZnO, TiO2, SnO2, and the doping element is selected from at least one of Al, Mg, Li, In, Ga; and / or The group II-VI semiconductor materials are selected from at least one of ZnS, ZnSe, CdS; and / or The group III-V semiconductor materials are selected from at least one of InP, GaP; and / or The group I-III-VI semiconductor materials are selected from at least one of CuInS, CuGaS.

7. A method for preparing a thin film, characterized in that, It includes: Provide a composite material solution, the composite material solution comprising a first modifier material, an N-type semiconductor material, and a first solvent, the first modifier material comprising maleimide and / or a maleimide derivative; Deposit the composite material solution to obtain a thin film.

8. The method for preparing a thin film according to claim 7, characterized in that, In the composite material solution, the concentration of the first modifier material is 1 mg / ml to 5 mg / ml, and the concentration of the N-type semiconductor material is 10 mg / ml to 50 mg / ml; and / or The first solvent in the composite material solution comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran, dinitrotoluene, ethanol, acetone; and / or The depositing the composite material solution to obtain a thin film comprises: depositing the composite material solution to obtain a first wet film layer, and performing a first annealing treatment on the first wet film layer to obtain a thin film, wherein the temperature of the first annealing treatment is 80 °C to 120 °C, and the time of the first annealing treatment is 5 minutes to 10 minutes.

9. The method for preparing the thin film according to claim 7, characterized in that, The composite material solution further comprises a second modifier material, the second modifier material comprising fulvalene and / or a fulvalene derivative, and the concentration of the second modifier material in the composite material solution is 1 mg / ml to 5 mg / ml.

10. A method for preparing a thin film, characterized in that, Comprises: Provide a first modifier material solution, the first modifier material solution comprising a first modifier material and a third solvent, the first modifier material comprising maleimide and / or a maleimide derivative, deposit the first modifier material solution to obtain a second wet film layer, and perform an annealing treatment on the second wet film layer to obtain a second sub-layer; Provide an N-type semiconductor material solution, the N-type semiconductor material solution comprising an N-type semiconductor material and a second solvent, deposit the N-type semiconductor material solution to obtain a first sub-layer, and form a thin film, the thin film comprising the second sub-layer and the first sub-layer stacked.

11. The method for preparing the thin film according to claim 10, characterized in that, In the N-type semiconductor material solution, the concentration of the N-type semiconductor material is 10 mg / ml to 50 mg / ml; and / or The second solvent in the N-type semiconductor material solution comprises at least one of methanol, ethanol, isobutanol, isopropanol, butanol; and / or In the first modifier material solution, the concentration of the first modifier material is 1 mg / ml to 5 mg / ml; and / or The third solvent in the first modifier material solution comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran, dinitrotoluene, ethanol, acetone; and / or The depositing the N-type semiconductor material solution to obtain a first sub-layer comprises: depositing the N-type semiconductor material solution to obtain a third wet film layer, and performing a second annealing treatment on the third wet film layer to obtain a first sub-layer, wherein the temperature of the second annealing treatment is 80 °C to 120 °C, and the time of the second annealing treatment is 5 minutes to 10 minutes; and / or The thickness ratio of the second sub-layer to the first sub-layer is (1 - 5):

30.

12. The method for preparing the thin film according to claim 10, wherein The preparation method of the thin film further includes: providing a second modifier material solution, the second modifier material solution including a second modifier material and a fourth solvent, the second modifier material including fulvalene and / or fulvalene derivatives, depositing the second modifier material solution to obtain a fourth wet film layer, and performing a third annealing treatment on the fourth wet film layer to obtain a third sub-layer; The thin film includes a second sub-layer, a first sub-layer, and a third sub-layer which are sequentially stacked.

13. The method for preparing the thin film according to claim 12, characterized in that, In the second modifier material solution, the concentration of the second modifier material is 1 mg / ml to 5 mg / ml; and / or The fourth solvent in the second modifier material solution includes at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropionamide, 1,2-dichloroethane, ethyl acetate, chloroform, dichloromethane, tetrahydrofuran, dinitrotoluene, ethanol, and acetone; and / or The thickness ratio of the third sub-layer, the first sub-layer, and the second sub-layer is (1 - 5):30:(1 - 5).

14. An optoelectronic device, characterized in that, It includes an anode and a cathode which are oppositely arranged, and N light-emitting unit layers and N - 1 charge generation layers disposed between the anode and the cathode, with one charge generation layer disposed between every two adjacent light-emitting unit layers, where N is an integer greater than or equal to 2; Each light-emitting unit layer includes a stacked light-emitting layer and an electron transport layer, where the electron transport layer is located on the side of the light-emitting layer close to the cathode; Wherein, at least one electron transport layer located between the charge generation layer and the light-emitting layer includes the thin film as described in any one of claims 1 - 6 or the thin film prepared by the preparation method as described in any one of claims 7 - 13.

15. The optoelectronic device according to claim 14, characterized in that, The optoelectronic device further includes a stacked hole injection layer and a hole transport layer, the hole injection layer and the hole transport layer are located between the light-emitting unit layer closest to the anode and the anode, and the hole transport layer is located on the side of the hole injection layer close to the cathode; and / or Each charge generation layer includes a stacked hole generation layer and an electron generation layer, and in each charge generation layer, the hole generation layer is disposed on the side of the electron generation layer close to the cathode.

16. The optoelectronic device according to claim 15, wherein The anode and the cathode each independently include a doped metal oxide particle electrode, a composite electrode, a graphene electrode, a carbon nanotube electrode, a metal elemental electrode or an alloy electrode. The material of the doped metal oxide particle electrode includes one or more of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the metal elemental electrode includes one or more of Ag, Al, Cu, Mo, Au, Pt, Ca, Mg, and Ba; and / or The materials of each light-emitting layer independently include one or more of an organic light-emitting material and a quantum dot light-emitting material. The organic light-emitting 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, a diarylanthracene 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 thermally activated delayed material, a polymer containing a B-N covalent bond, a hybrid local charge transfer excited state material, an exciplex light-emitting material, polyacetylene and its derivatives, poly(p-phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives;The quantum dot light-emitting material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell materials of the core-shell structure quantum dots are each independently selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds include one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The 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 one or more of CuInS2, CuInSe2, and AgInS2. 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 AMX3, where A is Cs; + ions, M is a divalent metal cation, including 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, including Cl - 、 Br - 、 I - one or more of; the structural general formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including 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, including Cl - 、 Br - 、 I - one or more of; and / or The materials of the hole transport layer include one or more of 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(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(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine, spiro-NPB, poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexoxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], 1,3-bis(carbazol-9-yl)benzene, polyaniline, polypyrrole, poly(p-phenylene vinylene), aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, doped graphene, undoped graphene, C60, doped or undoped NiO, doped or undoped MoO3, doped or undoped WO3, doped or undoped V2O5, doped or undoped p-type gallium nitride, doped or undoped CrO3, doped or undoped CuO; and / or The materials of the hole injection layer and the materials of each hole generation layer independently include one or more of 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, PEDOT, PEDOT:PSS, derivatives of PEDOT:PSS doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinodimethane, copper phthalocyanine, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide and copper oxide.

17. A display device, characterized in that, The optoelectronic device according to any one of claims 14-16.

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