Light-emitting device, preparation method thereof and display device

Abstract

The invention discloses a light-emitting device, a preparation method thereof and a display device. The light-emitting device comprises a cathode, a light-emitting layer, a ferroelectric material layer and an anode which are stacked in sequence, wherein the ferroelectric material layer comprises a polarization modified ferroelectric material. The luminescent device provided by the invention comprises the ferroelectric material layer and has relatively high hole mobility, so that the balance of electron-hole injection in the luminescent layer can be effectively promoted, and the luminescent device has relatively long service life.

Description

Technical Field

[0001] The present application relates to the technical field of light-emitting devices, and in particular, to a light-emitting device, a preparation method thereof, and a display device. Background Art

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

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

[0004] The lifespan of existing light-emitting devices is relatively short and needs to be further improved. Summary of the Invention

[0005] In view of this, the present application provides a light-emitting device, including a cathode, a light-emitting layer, a ferroelectric material layer, and an anode stacked in sequence, and the ferroelectric material layer includes a polarization-modified ferroelectric material.

[0006] Optionally, in some embodiments, the HOMO energy level of the polarization-modified ferroelectric material is -6 to -5 eV; and / or

[0007] The light-emitting layer includes an inorganic light-emitting material, and the valence band of the inorganic light-emitting material is -7 to -6 eV; and / or

[0008] The light-emitting layer includes an organic light-emitting material, and the valence band of the organic light-emitting material is -7 to -5.5 eV; and / or

[0009] The absolute value of the energy level difference between the polarization-modified ferroelectric material and the light-emitting material ranges from 0 to 0.5 eV; and / or

[0010] The dipole strength of the polarization-modified ferroelectric material is 0.1 to 20 Debye; and / or

[0011] The included angle between the dipole direction of the polarization-modified ferroelectric material and the light-emitting layer is 45° to 90°; and / or

[0012] The thickness of the ferroelectric material layer is 30 to 100 nm; and / or

[0013] The ferroelectric material layer includes polarized modified ferroelectric material fibers.

[0014] Optionally, in some embodiments, the polarized modified ferroelectric material includes a polarized modified organic ferroelectric material, and the polarized modified organic ferroelectric material includes one or more of polarized modified polyvinylidene fluoride, polarized modified vinylidene fluoride, polarized modified trifluoroethylene copolymer, and polarized modified polyurethane.

[0015] Optionally, in some embodiments, the HOMO energy level of the polarized modified polyvinylidene fluoride is -7 to -5 eV; and / or

[0016] The HOMO energy level of the polarized modified vinylidene fluoride is -7 to -5 eV; and / or

[0017] The HOMO energy level of the polarized modified trifluoroethylene copolymer is -6 to -5 eV; and / or

[0018] The HOMO energy level of the polarized modified polyurethane is -7 to -6 eV.

[0019] Optionally, in some embodiments, the ferroelectric material layer has a number of mesopores.

[0020] Optionally, in some embodiments, the pore diameter of the mesopores is 5 to 20 nm; and / or

[0021] The cathode and the anode each independently include a doped metal oxide 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 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, aluminum-doped magnesium oxide, and cadmium-doped zinc oxide. The composite electrode includes AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, or BaF2 / Ca / Al. The material of the metal elemental electrode includes one or more of Ag, Ni, Pt, Au, Ir, Cu, Mo, Al, Ca, Mg, and Ba. The alloy electrode includes an Au:Mg alloy electrode or an Ag:Mg alloy electrode; and / or

[0022] 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; and / or

[0023] The inorganic luminescent material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The shell layer of the core-shell structure quantum dots includes one or more layers. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell layer 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+ and Sn 2+, Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2+ , Yb 2+ , Eu 2+ One or more of the following, X is a halogen anion, including Cl-, Br - , I - One or more of the following; 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 the following, X is a halogen anion, including Cl - , Br - , I - One or more of the following; and / or

[0024] The light-emitting device further includes an electron transport layer, which is located between the cathode and the light-emitting layer. The material of the electron transport layer includes one or more of inorganic electron transport materials and organic electron transport materials. The inorganic electron transport materials include one or more of metal oxides, doped metal oxides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The metal oxides include one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the doped metal oxides include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3, and the dopants in the doped metal oxides include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, and Sn. The IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include one or more of CuInS and CuGaS. The organic electron transport materials include one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, and hydroxyquinoline compounds.

[0025] Correspondingly, an embodiment of the present application further provides a method for manufacturing a light-emitting device, including the following steps:

[0026] Provide a light-emitting device preform, which includes a stacked cathode and a light-emitting layer;

[0027] Deposit a polarized modified ferroelectric material on the light-emitting device preform to obtain a ferroelectric material layer;

[0028] Fabricate an anode on the ferroelectric material layer to obtain a light-emitting device;

[0029] Or,

[0030] Provide a light-emitting device preform, which includes an anode;

[0031] Deposit a polarized modified ferroelectric material on the light-emitting device preform to obtain a ferroelectric material layer;

[0032] Successively fabricate a stacked light-emitting layer and a cathode on the ferroelectric material layer to obtain a light-emitting device.

[0033] Optionally, in some embodiments, depositing the polarized modified ferroelectric material on the light-emitting device preform includes:

[0034] An unpolarized modified ferroelectric material is provided. In an electric field, the unpolarized modified ferroelectric material is deposited on the light-emitting device preform to form the polarized modified ferroelectric material.

[0035] Optionally, in some embodiments, the method of depositing the unpolarized modified ferroelectric material on the light-emitting device preform is the electrospinning method.

[0036] Optionally, in some embodiments, depositing the unpolarized modified ferroelectric material on the light-emitting device preform includes:

[0037] Dissolve the unpolarized modified ferroelectric material in a solvent to obtain an unpolarized modified ferroelectric material solution;

[0038] In an electric field, the unpolarized modified ferroelectric material solution is deposited on the light-emitting device preform by electrospinning.

[0039] Optionally, in some embodiments, the unpolarized modified ferroelectric material includes an unpolarized modified organic ferroelectric material, and the unpolarized modified organic ferroelectric material includes one or more of unpolarized modified polyvinylidene fluoride, unpolarized modified vinylidene fluoride, unpolarized modified trifluoroethylene copolymer, and unpolarized modified polyurethane; and / or

[0040] The solvent includes one or more of dimethyl sulfoxide, chloroform, and dimethylformamide; and / or

[0041] The concentration of the unpolarized modified ferroelectric material solution is 1-10 wt%.

[0042] Optionally, in some embodiments, the direction of the electric field forms an angle of 45°-90° with the light-emitting device preform; and / or

[0043] The intensity of the electric field is 0.5-10 MV / m; and / or

[0044] The ejection rate of the unpolarized modified ferroelectric material solution in the electrospinning is 0.05-5 mL / h; and / or

[0045] The filament-forming voltage of the electrospinning is 5-15 kV; and / or

[0046] The filament-forming distance of the electrospinning is 1-3 nm.

[0047] Correspondingly, an embodiment of the present application further provides a display device, including the light-emitting device described above.

[0048] The light-emitting device described in the present application includes the ferroelectric material layer, which has a high hole mobility and can effectively promote the balance of electron-hole injection in the light-emitting layer, so that the light-emitting device has a high lifespan. Description of the Drawings

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0050] Figure 1 is a schematic structural diagram of a light-emitting device provided by an embodiment of the present application;

[0051] Figure 2 is a TEM image of the ferroelectric material layer provided by an embodiment of the present application;

[0052] Figure 3 is a schematic structural diagram of another light-emitting device provided by an embodiment of the present application;

[0053] Figure 4 is a flowchart of a method for manufacturing a light-emitting device provided by an embodiment of the present application;

[0054] Figure 5 is a flowchart of a method for manufacturing another light-emitting device provided by an embodiment of the present application.

[0055] Reference Signs:

[0056] Light-emitting device 100; Cathode 10; Light-emitting layer 20; Ferroelectric material layer 30; Anode 40; Electron transport layer 50. Detailed Embodiments

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0059] In this application, unless otherwise stated, the orientation terms such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "comprising" means "including but not limited to". The use of terms such as first, second, third, etc. is only for marking purposes and does not impose a numerical requirement or establish an order.

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

[0061] In this application, "at least one" means one or more, and "a plurality" means two or more. "One or more", "at least one of the following (items)" or similar expressions refer to any combination of these items, including any combination of single (item) or plural items (items). For example, "at least one of (item) a, b, or c", or, "at least one of (item) a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

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

[0063] Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0064] The technical solution of the present application is as follows:

[0065] In a first aspect, please refer to Figure 1 , an embodiment of the present application provides a light-emitting device 100, including a cathode 10, a light-emitting layer 20, a ferroelectric material layer 30, and an anode 40 stacked in sequence. The ferroelectric material layer 30 includes a polarization-modified ferroelectric material.

[0066] It should be noted that in the present application, the polarization-modified ferroelectric material refers to a ferroelectric material that has undergone polarization treatment.

[0067] The HOMO energy level of the polarization-modified ferroelectric material is -6 to -5 eV, for example, -6 eV, -5.8 eV, -5.6 eV, -5.5 eV, -5.2 eV, -5.0 eV, etc.

[0068] The light-emitting layer 20 includes an inorganic light-emitting material and / or an organic light-emitting material. The valence band range of the inorganic light-emitting material is -7 to -6 eV, for example, -6 eV, -6.2 eV, -6.4 eV, -6.5 eV, -6.6 eV, -6.8 eV, -7 eV, etc. The valence band of the organic light-emitting material is -7 to -5.5 eV, for example, -5.5 eV, -5.8 eV, -6 eV, -6.2 eV, -6.4 eV, -6.5 eV, -6.6 eV, -6.8 eV, -7 eV, etc.

[0069] The absolute value of the energy level difference between the polarization-modified ferroelectric material and the light-emitting material is 0 to 0.5 eV, for example, 0 eV, 0.1 eV, 0.2 eV, 0.3 eV, 0.4 eV, 0.5 eV, etc. In this way, the intrinsic hole injection barrier between the ferroelectric material layer 30 and the light-emitting layer 20 can be effectively reduced, which is beneficial to improving the hole injection efficiency of the light-emitting device 100, and further improving the performance such as the efficiency and lifespan of the light-emitting device 100.

[0070] In some embodiments, the polarization-modified ferroelectric material includes, but is not limited to, a polarization-modified organic ferroelectric material. The polarization-modified organic ferroelectric material includes, but is not limited to, one or more of polarization-modified polyvinylidene fluoride (PVDF), polarization-modified vinylidene fluoride, polarization-modified poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE), and polarization-modified polyurethane (PU). The polarization-modified organic ferroelectric material has an energy level similar to that of the inorganic luminescent material and / or organic luminescent material of the light-emitting layer. Thus, the intrinsic hole injection barrier between the ferroelectric material layer 30 and the light-emitting layer 20 can be effectively reduced, which is beneficial to improving the hole injection efficiency of the light-emitting device 100, and further improving the performance such as the efficiency and lifetime of the light-emitting device 100.

[0071] In some embodiments, the HOMO energy level of the polarization-modified PVDF and the polarization-modified vinylidene fluoride is independently -7 to -5 eV, the HOMO energy level of the polarization-modified PVDF-TrFE is -6 to -5 eV, and the HOMO energy level of the polarization-modified PU is -7 to -6 eV.

[0072] The dipole strength of the polarization-modified ferroelectric material ranges from 0.1 to 20 Debye, for example, 0.1 Debye, 1 Debye, 2 Debye, 4 Debye, 5 Debye, 6 Debye, 7 Debye, 8 Debye, 10 Debye, 12 Debye, 14 Debye, 15 Debye, 16 Debye, 17 Debye, 18 Debye, 19 Debye, 20 Debye, etc. The stronger the dipole, the deeper the HOMO energy level. Therefore, within the range of the dipole strength, the energy difference between the polarization-modified ferroelectric material of the ferroelectric material layer 30 and the luminescent material of the light-emitting layer 20 is small, so that the hole injection barrier between the ferroelectric material layer 30 and the light-emitting layer 20 can be small, which is beneficial to improving the hole injection efficiency of the light-emitting device 100, and further improving the performance such as the efficiency and lifetime of the light-emitting device 100.

[0073] The included angle between the dipole direction of the polarization-modified ferroelectric material and the light-emitting layer 20 is 45° to 90°, for example, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, etc.

[0074] In some embodiments, the thickness of the ferroelectric material layer 30 is 30 to 100 nm. Within this thickness range, the ferroelectric material layer 30 can have good film-forming properties, which is beneficial to forming a continuous thin film, and is also beneficial to the rapid and effective injection of holes in the light-emitting device 100 into the light-emitting layer 20.

[0075] Please refer to Figure 2 , the ferroelectric material layer 30 includes polarization-modified ferroelectric material fibers.

[0076] Please refer to Figure 2, the ferroelectric material layer 30 has a number of mesopores. In other words, the ferroelectric material layer 30 has a mesoporous morphology, which can effectively increase the contact area between the polarization-modified ferroelectric material and the luminescent material, thereby further effectively improving the hole injection efficiency of the light-emitting device 100.

[0077] In some embodiments, the pore diameter of the mesopores in the ferroelectric material layer 30 ranges from 5 to 20 nm.

[0078] The light-emitting device 100 of the present application includes the ferroelectric material layer 30, which has a relatively high hole mobility and can effectively promote the balance of electron-hole injection in the light-emitting layer 20, so that the light-emitting device 100 has a relatively high luminous efficiency and service life. In addition, compared with the prior art that uses a hole injection layer and / or a hole transport layer to reduce the hole injection barrier between the anode and the light-emitting layer, the present application reduces the hole injection barrier between the anode and the light-emitting layer through the ferroelectric material layer 30, which can effectively simplify the manufacturing process and reduce costs. Further, the present application uses a single ferroelectric material layer 30 to control its polarization degree to regulate the hole injection barrier, so as to replace two organic semiconductor materials (hole injection layer and hole transport layer). In this way, while achieving the purpose of reducing costs, the flexibility of material selection in device manufacturing is also improved.

[0079] Please refer to Figure 3 , in some embodiments, the light-emitting device 100 further includes an electron transport layer 50, and the electron transport layer 50 is located between the cathode 10 and the light-emitting layer 20.

[0080] The cathode 10 and the anode 40 are an anode and a cathode known in the art for light-emitting devices. For example, they can independently include but are not limited to doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The materials of the doped metal oxide electrodes can include but are not limited to one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), aluminum-doped magnesium oxide (AMO), and cadmium-doped zinc oxide. The composite electrode is an electrode formed by laminating two or more layers of conductive materials, such as 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, ZnS / Al / ZnS, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. Herein, " / " represents a laminated structure. For example, AZO / Ag / AZO represents a composite electrode including an AZO layer, an Ag layer, and an AZO layer laminated in sequence. The materials of the elemental metal electrodes can include but are not limited to one or more of Ag, Ni, Pt, Au, Ir, Cu, Mo, Al, Ca, Mg, and Ba. The alloy electrodes include but are not limited to Au:Mg alloy electrodes and Ag:Mg alloy electrodes.

[0081] In some embodiments, the anode is an electrode with a relatively high work function. For example, it can include but is not limited to doped metal oxide electrodes with a relatively high work function, elemental metal electrodes with a relatively high work function, and carbon nanotube electrodes. The elemental metal electrodes with a relatively high work function can be selected from but are not limited to Ni, Pt, Au, Ag, Ir, etc.

[0082] In some embodiments, the cathode is an electrode with a relatively low work function. For example, it can include but is not limited to elemental metal electrodes with a relatively low work function, composite electrodes with a relatively low work function, and alloy electrodes with a relatively low work function. The elemental metal electrodes with a relatively low work function can be Ca, Ba, Al, Mg, etc. The composite electrodes with a relatively low work function can be Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, BaF2 / Ca / Al, etc. The alloy electrodes with a relatively low work function are Au:Mg and Ag:Mg, etc.

[0083] The organic light-emitting material may include, but is not limited to, one or more of CBP:Ir(mppy)3 (4,4'-bis(N-carbazolyl)-1,1'-biphenyl: tris[2-(p-tolyl)pyridine iridium(III)]), TCTX:Ir(mmpy) (4,4',4”-tris(carbazol-9-yl)triphenylamine: tris[2-(p-tolyl)pyridine iridium]), diarylanthracene derivatives, stilbene aromatic derivatives, pyrene derivatives, fluorene derivatives, TBPe fluorescent materials, TTPX fluorescent materials, TBRb fluorescent materials, DBP fluorescent materials, delayed fluorescence materials, TTA materials, TADF (thermally activated delayed) materials, polymers containing B-N covalent bonds, HLCT (hybrid local charge transfer excited state) materials, Exciplex (exciplex) light-emitting materials, polyacetylene and its derivatives, poly(phenylene) and its derivatives, polythiophene and its derivatives, polyfluorene and its derivatives.

[0084] The inorganic light-emitting material may include, but is not limited to, one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The shell layer of the core-shell structure quantum dots includes one or more layers.

[0085] 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 may respectively include, but are not limited to, one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds, and I-III-VI group compounds. The II-VI group compounds may include, but are not limited to, 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 may include, but are not limited to, 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 may include, but are not limited to, 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 may include, but are not limited to, one or more of CuInS2, CuInSe2, and AgInS2.

[0086] As an example, the quantum dots of the core-shell structure may include, but are not limited to, one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS.

[0087] The perovskite semiconductor material may include, but is not limited to, doped or undoped inorganic perovskite semiconductors, or organic-inorganic hybrid perovskite semiconductors. The general structural formula of the inorganic perovskite semiconductor is AMX3, where A is a Cs + ion, 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+ and one or more of them, X is a halogen anion, including Cl - , Br - , I - and one or more of them. The general structural 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+ and one or more of them, X is a halogen anion, including Cl - , Br - , I - and one or more of them.

[0088] The material of the electron transport layer 50 is a material known in the art for electron transport layers, and can be selected from, for example, but not limited to, one or more of inorganic electron transport materials and organic electron transport materials. The inorganic electron transport materials include, but are not limited to, one or more of metal oxides, doped metal oxides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. Specifically, the metal oxide is selected from, for example, but not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5; the metal oxide in the doped metal oxide is selected from, for example, but not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3, and the dopant in the doped metal oxide is selected from, for example, but not limited to, one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Sn. By way of example, the doped metal oxide can be aluminum-doped zinc oxide (AZO), lithium-doped zinc oxide (LZO), magnesium-doped zinc oxide (MZO), tin-doped zinc oxide, etc.; the IIB-VIA group semiconductor material is selected from, for example, but not limited to, one or more of ZnS, ZnSe, CdS; the IIIA-VA group semiconductor material is selected from, for example, but not limited to, one or more of InP, GaP; the IB-IIIA-VIA group semiconductor material is selected from, for example, but not limited to, one or more of CuInS, CuGaS. The organic electron transport materials include, but are not limited to, one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds.

[0089] It can be understood that the light-emitting device 100 can also be provided with some functional layers that are commonly used in light-emitting devices and are helpful for improving the performance of the light-emitting device, such as an electron blocking layer, a hole blocking layer, an electron injection layer, an interface modification layer, etc.

[0090] It can be understood that the materials of the respective layers of the light-emitting device 100 can be adjusted according to the light-emitting requirements of the light-emitting device 100.

[0091] In some embodiments, the light-emitting device 100 further includes a substrate, and the substrate is disposed on a side of the cathode 10 away from the light-emitting layer 20, or the substrate is disposed on a side of the anode 40 away from the light-emitting layer 20.

[0092] The substrate can be a rigid substrate or a flexible substrate. In some embodiments, the material of the substrate can include, but is not limited to, one or more of glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0093] It can be understood that the light-emitting device 100 can be a normal light-emitting device or an inverted light-emitting device. The light-emitting device 100 can be a quantum dot light-emitting device or an organic light-emitting device.

[0094] In a second aspect, please refer to Figure 4 , an embodiment of the present application further provides a method for manufacturing a light-emitting device, including the following steps:

[0095] Step S11: Provide a light-emitting device preform, where the light-emitting device preform includes a stacked cathode 10 and a light-emitting layer 20;

[0096] Step S12: Deposit a polarized modified ferroelectric material on the light-emitting device preform to obtain a ferroelectric material layer 30;

[0097] Step S13: Prepare an anode 40 on the ferroelectric material layer 30 to obtain the light-emitting device 100.

[0098] Please refer to Figure 3 , in some embodiments, the light-emitting device preform further includes an electron transport layer 50 located between the cathode 10 and the light-emitting layer 20.

[0099] Please refer to Figure 4 , an embodiment of the present application further provides another method for manufacturing a light-emitting device, including the following steps:

[0100] Step S21: Provide a light-emitting device preform, where the light-emitting device preform includes an anode 40;

[0101] Step S22: Deposit a polarized modified ferroelectric material on the light-emitting device preform to obtain a ferroelectric material layer 30;

[0102] Step S23: Sequentially prepare a stacked light-emitting layer 20 and a cathode 10 on the ferroelectric material layer 30 to obtain the light-emitting device 100.

[0103] Please refer to Figure 3 , in some embodiments, step S13 includes: sequentially preparing a stacked light-emitting layer 20, an electron transport layer 50, and an anode 40 on the ferroelectric material layer 30.

[0104] In the above two manufacturing methods:

[0105] In some embodiments, the method of depositing a polarized modified ferroelectric material on the light-emitting device preform includes:

[0106] Provide an unpolarized modified ferroelectric material, in an electric field, deposit the unpolarized modified ferroelectric material on the light-emitting device preform. During the deposition process, the electric field can polarize the unpolarized modified ferroelectric material to obtain a polarized modified ferroelectric material, thereby obtaining the ferroelectric material layer 30.

[0107] The unpolarized modified ferroelectric material includes but is not limited to unpolarized modified organic ferroelectric materials. The unpolarized modified organic ferroelectric materials include but are not limited to one or more of unpolarized modified polyvinylidene fluoride (PVDF), unpolarized modified vinylidene fluoride, unpolarized modified trifluoroethylene copolymer (PVDF-TrFE), and unpolarized modified polyurethane (PU).

[0108] In some embodiments, the direction of the electric field forms an angle of 45° to 90° with the light-emitting device preform. For example, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°, etc.

[0109] In some embodiments, the magnitude of the electric field strength is 0.5 to 10 MV / m. For example, 0.5 MV / m, 1 MV / m, 2 MV / m, 3 MV / m, 4 MV / m, 5 MV / m, 6 MV / m, 7 MV / m, 8 MV / m, 9 MV / m, 10 MV / m, etc. Within this range, the dipole of the ferroelectric material can be effectively controlled to deflect, which is beneficial to controlling the dipole orientation of the ferroelectric material, and is beneficial to making the prepared ferroelectric material layer 30 have a better dipole strength, thereby being beneficial to reducing the hole injection barrier between the anode 40 and the light-emitting layer 20.

[0110] In some embodiments, the method of depositing the unpolarized modified ferroelectric material on the light-emitting device preform is the electrospinning method.

[0111] In at least some embodiments, the method of depositing the unpolarized modified ferroelectric material on the light-emitting device preform includes:

[0112] Step S21: Dissolve the unpolarized modified ferroelectric material in a solvent to obtain an unpolarized modified ferroelectric material solution;

[0113] Step S22: In an electric field, deposit the unpolarized modified ferroelectric material solution on the light-emitting device preform by the electrospinning method.

[0114] In some embodiments, the solvent includes but is not limited to one or more of dimethyl sulfoxide (DMSO), chloroform, and dimethylformamide (DMF).

[0115] In some embodiments, the concentration range of the unpolarized modified ferroelectric material solution is 1 to 10 wt%. Within this concentration range, the electric field can fully and effectively polarize and modify the unpolarized modified ferroelectric material, and a ferroelectric material layer 30 with good film-forming properties can be obtained.

[0116] In some embodiments, the injection (spraying) rate of the unpolarized and modified ferroelectric material solution in the electrospinning is 0.05 - 5 mL / h. For example, 0.05 mL / h, 0.5 mL / h, 1 mL / h, 1.5 mL / h, 2 mL / h, 2.5 mL / h, 3 mL / h, 3.5 mL / h, 4 mL / h, 4.5 mL / h, 5 mL / h. Within this rate range, on the one hand, the unpolarized and modified ferroelectric material solution can be fully stretched, and the solvent can be fully evaporated. Thus, it is beneficial to prepare fibers with a smaller diameter. On the other hand, the fibers formed by electrospinning can be evenly distributed. On the further hand, it is beneficial to prepare fibers with better toughness.

[0117] In some embodiments, the filament-forming voltage of the electrospinning (the voltage applied to the spinneret of the electrospinning device) is 5 - 15 kV. For example, 5 kV, 6 kV, 7 kV, 8 kV, 9 kV, 10 kV, 11 kV, 12 kV, 13 kV, 14 kV, 15 kV, etc. Within this range, it is beneficial for rapid and stable filament formation and is also beneficial for preparing fibers with a uniform diameter distribution.

[0118] In some embodiments, the filament-forming distance of the electrospinning is 1 - 3 nm. For example, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, etc. Within this range, it is beneficial to prepare fibers with a uniform diameter and a uniform distribution, thereby improving the uniformity of the film formation.

[0119] It should be noted that the filament-forming distance described in this application refers to the vertical distance between the spinneret of the electrospinning device and the preform of the light-emitting device.

[0120] The methods for forming the light-emitting layer 20, the anode 40, and the electron transport layer 50 can be implemented by conventional techniques in the art, such as chemical methods or physical methods. Among them, chemical methods include chemical vapor deposition, sequential ionic layer adsorption and reaction, anodic oxidation, electro-deposition, co-precipitation. Physical methods include physical coating methods and solution methods. Among them, physical coating methods include: thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion plating, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.; solution methods can be spin coating, printing, inkjet printing, blade coating, printing, dip coating, immersion, spraying, roll coating, casting, slot die coating, and bar coating, etc.

[0121] The preparation method of the light-emitting device described in the present application uses an electrospinning process in combination with the application of an electric field to prepare a ferroelectric material layer 30 with a mesoporous morphology. By applying the electric field and controlling the electric field strength, a ferroelectric material layer 30 with a specific dipole orientation and dipole strength is prepared, so that the prepared light-emitting device 100 has a high luminous efficiency and a long lifespan.

[0122] In a third aspect, the present application also relates to a display device, which includes the light-emitting device 100.

[0123] The display device can be any electronic product with a display function. The electronic products include but are not limited to smartphones, tablet computers, laptop computers, digital cameras, digital video cameras, smart wearable devices, smart weighing electronic scales, in-vehicle displays, televisions, or e-book readers. Among them, the smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.

[0124] The present application will be specifically described below through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application. The raw materials used in the following embodiments are all commercially available products unless otherwise specified.

[0125] Example 1

[0126] Provide an ITO anode 40 glass substrate with a thickness of 20 nm;

[0127] On the anode 40, use an electrospinning device (Nafiber, SR-100) to deposit a ferroelectric material layer 30 with a thickness of 30 nm by electrospinning. Among them, the unpolarized modified ferroelectric material solution is an unpolarized modified PVDF solution with a concentration of 5 wt% (dissolved in DMSO). The injection rate of the unpolarized modified ferroelectric material solution is 0.1 mL / h. Apply a filament-forming voltage of 10 kV to the spinneret. Apply an external electric field perpendicular to the substrate direction during deposition. The electric field strength is 5 MV / m. The electric field direction is from the substrate to the spinneret. The deposition time is 10 min. The ferroelectric material layer 30 includes polarized modified PVDF;

[0128] Spin-coat a CdSe blue quantum dot solution with a concentration of 20 mg / mL on the ferroelectric material layer 30 at a speed of 2000 rpm for 30 s to obtain a light-emitting layer 20 with a thickness of 30 nm;

[0129] Spin-coat an ethanol solution of ZnO with a concentration of 30 mg / mL on the light-emitting layer 20 at a speed of 3000 rpm for 30 s, and then heat at 80 °C for 10 minutes to obtain an electron transport layer 50 with a thickness of 30 nm;

[0130] On the electron transport layer 50, Ag is deposited by thermal evaporation under a vacuum degree not higher than 3×10 -4 Pa at a rate of 1 Å / s for 1000 seconds to obtain a cathode 10 with a thickness of 100 nm;

[0131] Package to obtain the light-emitting device 100.

[0132] Example 2

[0133] This example is basically the same as Example 1, except that in this example, unpolarized modified PVDF-TrFE is used to replace the unpolarized modified PVDF in Example 1.

[0134] Example 3

[0135] This example is basically the same as Example 1, except that in this example, unpolarized modified PU is used to replace the unpolarized modified PVDF in Example 1.

[0136] Example 4

[0137] The example is basically the same as Example 1, except that in this example, unpolarized modified vinylidene fluoride is used to replace the unpolarized modified PVDF in Example 1.

[0138] Example 5

[0139] The example is basically the same as Example 1, except that in this example, the electric field strength is 0.5 MV / m.

[0140] Example 6

[0141] The example is basically the same as Example 1, except that in this example, the electric field strength is 10 MV / m.

[0142] Example 7

[0143] The example is basically the same as Example 1, except that in this example, the thickness of the unpolarized modified ferroelectric material layer 30 is 50 nm.

[0144] Example 8

[0145] The example is basically the same as Example 1, except that in this example, the thickness of the unpolarized modified ferroelectric material layer 30 is 100 nm.

[0146] Example 9

[0147] The example is basically the same as Example 1, except that in this example, the injection rate of the unpolarized modified ferroelectric material solution is 0.05 mL / h.

[0148] Example 10

[0149] The embodiment is basically the same as Embodiment 1, except that in this embodiment, the injection rate of the non-polarized modified ferroelectric material solution is 5 mL / h.

[0150] Embodiment 11

[0151] The embodiment is basically the same as Embodiment 1, except that in this embodiment, the wire-forming voltage is 5 kV.

[0152] Embodiment 12

[0153] The embodiment is basically the same as Embodiment 1, except that in this embodiment, the wire-forming voltage is 15 kV.

[0154] Embodiment 13

[0155] The embodiment is basically the same as Embodiment 1, except that in this embodiment, CdSe red quantum dots are used to replace the CdSe blue quantum dots in Embodiment 1.

[0156] Embodiment 14

[0157] The embodiment is basically the same as Embodiment 1, except that in this embodiment, CdSe green quantum dots are used to replace the CdSe blue quantum dots in Embodiment 1.

[0158] Comparative Example 1

[0159] Provide an ITO anode 40 with a thickness of 20 nm;

[0160] Spin-coat PEDOT:PSS material on the anode 40, where the spin-coating speed is 5000 rpm, the time is 30 seconds, and then heat at 150 °C for 15 minutes to obtain a hole injection layer with a thickness of 30 nm;

[0161] Spin-coat TFB (8 mg / mL) on the hole injection layer, where the spin-coating speed is 3000, the time is 30 seconds, and then heat at 80 °C for 10 minutes to obtain a hole transport layer with a thickness of 30 nm;

[0162] Spin-coat a CdSe blue quantum dot solution with a concentration of 20 mg / mL on the hole transport layer at a speed of 2000 rpm for 30 s to obtain a light-emitting layer 20 with a thickness of 30 nm;

[0163] Spin-coat an ethanol solution of ZnO with a concentration of 30 mg / mL on the light-emitting layer 20 at a speed of 3000 rpm for 30 s, and then heat at 80 °C for 10 minutes to obtain an electron transport layer 50 with a thickness of 30 nm;

[0164] On the electron transport layer 50 by thermal evaporation, the vacuum degree is not higher than 3×10 -4Deposit Ag by evaporation at a rate of 1 Å / s for 1000 s to obtain a cathode 10 with a thickness of 100 nm;

[0165] Encapsulate to obtain a light-emitting device 100.

[0166] Comparative Example 2

[0167] This comparative example is basically the same as Comparative Example 1, except that in this comparative example, CdSe red quantum dots are used to replace the CdSe blue quantum dots in Comparative Example 1.

[0168] Comparative Example 3

[0169] This comparative example is basically the same as Comparative Example 1, except that in this comparative example, CdSe green quantum dots are used to replace the CdSe blue quantum dots in Comparative Example 1.

[0170] Perform TEM testing on the ferroelectric material layer of Example 1 to obtain Figure 2 the TEM image shown. It can be seen from Figure 2 that the ferroelectric material layer has fibers and mesopores, presenting a mesoporous morphology.

[0171] Detect the maximum brightness L max , lifetime T95, lifetime T95@1000 nit, and dipole strength of the ferroelectric material layer 30 of the light-emitting devices in Examples 1 to 14 and Comparative Examples 1 to 3. The test results are shown in Table 1.

[0172] Among them:

[0173] The test methods for lifetime T95 and lifetime T95@1000 nit are as follows: The time required for the device to reduce the brightness to a certain proportion of the maximum brightness under a constant current drive of 2 mA. The time when the brightness drops to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the test cycle, the device lifetime test is usually carried out by accelerating the device aging at high brightness and fitting the lifetime at high brightness through an extended exponential decay brightness decay fitting formula. For example, the lifetime at 1000 nit is denoted as T95@1000 nit. The specific calculation formula is as follows:

[0174]

[0175] Among them, T95 L is the lifetime at low brightness, T95 H is the measured lifetime at high brightness, L H is the device accelerated to the maximum brightness, L L is 1000 nit, A is the acceleration factor, and in this experiment, the A value is obtained as 1.7 by measuring the lifetimes of several groups of green QLED devices at the rated brightness.

[0176] The maximum brightness is measured using a PR650 luminance meter, with a constant driving current of 2 mA.

[0177] The test method for dipole strength is as follows: Use a Keysight B1500A semiconductor parameter analyzer, in conjunction with a B1530A generator unit module, to characterize the polarization intensity of the material.

[0178] The test method for the turn-on voltage (V) of a single-hole device is as follows: Use the ferroelectric material layer 30 of Examples 1 to 14 as the hole functional layer to fabricate a single-hole device with the structure of anode / ferroelectric material layer / quantum dot light-emitting layer / cathode; use the stacked hole transport layer and hole injection layer of Comparative Examples 1 to 3 as the hole functional layer to fabricate a single-hole device with the structure of anode / hole injection layer / hole transport layer / light-emitting layer / cathode. Obtain the voltage value when the brightness of the single-hole device reaches 1 nit in the efficiency test system built with a Keithley 6485 to obtain the turn-on voltage of the single-hole device.

[0179] The environmental conditions for the above tests are as follows: Conducted at room temperature, with an air humidity of 30 - 60%.

[0180] Table 1:

[0181]

[0182] As can be seen from Table 1:

[0183] The polarization-modified ferroelectric material in the ferroelectric material layer of the light-emitting devices of Examples 1 to 14 has dipole strength, while the hole transport layer material and hole injection layer material of the light-emitting devices of Comparative Examples 1 to 3 do not have dipole strength;

[0184] Compared with the light-emitting device of Comparative Example 1, the light-emitting devices of Examples 1 to 12 have a similar or even lower turn-on voltage, a similar or even higher maximum brightness, and a similar or even longer lifespan. It can be seen that setting the ferroelectric material layer of the present application between the anode and the light-emitting layer can achieve an effect similar to or even better than that of the stacked structure of the hole injection layer and the hole transport layer. The reason may be that the ferroelectric material layer of the present application has good hole injection performance, which can make the electron-hole injection of the light-emitting device more balanced;

[0185] Compared with the light-emitting device of Comparative Example 2, the light-emitting device of Example 13 has a similar or even lower turn-on voltage, a similar or even higher maximum brightness, and a similar or even longer lifespan. It can be seen that setting the ferroelectric material layer of the present application between the anode and the light-emitting layer can achieve an effect similar to or even better than that of the stacked structure of the hole injection layer and the hole transport layer. The reason may be that the ferroelectric material layer of the present application has good hole injection performance, which can make the electron-hole injection of the light-emitting device more balanced;

[0186] Compared with the light-emitting device of Comparative Example 3, the light-emitting device of Example 14 has a similar or even lower turn-on voltage, a similar or even higher maximum brightness, and a similar or even longer lifespan. It can be seen that by disposing the ferroelectric material layer of the present application between the anode and the light-emitting layer, an effect similar to or even better than that of the stacked structure of the hole injection layer and the hole transport layer can be achieved. The reason may be that the ferroelectric material layer of the present application has good hole injection performance, which can make the electron-hole injection of the light-emitting device more balanced.

[0187] The present application achieves an effect similar to or even better than that of a conventional hole transport layer and a hole injection layer by disposing a ferroelectric material layer including a polarization-modified ferroelectric material between the anode and the light-emitting layer.

[0188] The technical solutions provided by the embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A light-emitting device, comprising a cathode, a light-emitting layer, a ferroelectric material layer, and an anode stacked in sequence, characterized in that, The ferroelectric material layer includes a polarization-modified ferroelectric material.

2. The light-emitting device according to claim 1, characterized in that, The HOMO energy level of the polarization-modified ferroelectric material is -6 to -5 eV; and / or The light-emitting layer includes an inorganic light-emitting material, and the valence band of the inorganic light-emitting material is -7 to -6 eV; and / or The light-emitting layer includes an organic light-emitting material, and the valence band of the organic light-emitting material is -7 to -5.5 eV; and / or The absolute value of the energy level difference between the polarization-modified ferroelectric material and the light-emitting material is 0 to 0.5 eV; and / or The dipole strength of the polarization-modified ferroelectric material is 0.1 to 20 Debye; and / or The included angle between the dipole direction of the polarization-modified ferroelectric material and the light-emitting layer is 45° to 90°; and / or The thickness of the ferroelectric material layer is 30 to 100 nm; and / or The ferroelectric material layer includes polarization-modified ferroelectric material fibers.

3. The light-emitting device according to claim 1, characterized in that, The polarization-modified ferroelectric material includes a polarization-modified organic ferroelectric material, and the polarization-modified organic ferroelectric material includes one or more of polarization-modified polyvinylidene fluoride, polarization-modified vinylidene fluoride, polarization-modified trifluoroethylene copolymer, and polarization-modified polyurethane.

4. The light-emitting device according to claim 3, characterized in that, The HOMO energy level of the polarization-modified polyvinylidene fluoride is -7 to -5 eV; and / or The HOMO energy level of the polarization-modified vinylidene fluoride is -7 to -5 eV; and / or The HOMO energy level of the polarization-modified trifluoroethylene copolymer is -6 to -5 eV; and / or The HOMO energy level of the polarization-modified polyurethane is -7 to -6 eV.

5. The light-emitting device according to claim 1, characterized in that, The ferroelectric material layer has a number of mesopores.

6. The light-emitting device according to any one of claims 1 to 5, characterized in that, The pore diameter of the mesopores is 5 to 20 nm; and / or The cathode and the anode each independently include a doped metal oxide 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 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, aluminum-doped magnesium oxide, and cadmium-doped zinc oxide. The composite electrode includes AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, Ca / Al, LiF / Ca, LiF / Al, BaF2 / Al, CsF / Al, CaCO3 / Al, or BaF2 / Ca / Al. The material of the metal elemental electrode includes one or more of Ag, Ni, Pt, Au, Ir, Cu, Mo, Al, Ca, Mg, and Ba. The alloy electrode includes an Au:Mg alloy electrode or an Ag:Mg alloy electrode; and / or 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; and / or The inorganic luminescent material includes one or more of single-structure quantum dots, core-shell structure quantum dots, and perovskite semiconductor materials. The shell layer of the core-shell structure quantum dots includes one or more layers. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots, and the shell layer 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+ and 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 light-emitting device further includes an electron transport layer, which is located between the cathode and the light-emitting layer. The material of the electron transport layer includes one or more of inorganic electron transport materials and organic electron transport materials. The inorganic electron transport materials include one or more of metal oxides, doped metal oxides, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The metal oxides include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5; the metal oxides in the doped metal oxides include one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, Al2O3, and the dopants in the doped metal oxides include one or several of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, Ga, Sn; the IIB-VIA group semiconductor materials include one or more of ZnS, ZnSe, CdS; the IIIA-VA group semiconductor materials include one or more of InP, GaP; the IB-IIIA-VIA group semiconductor materials include one or more of CuInS, CuGaS; the organic electron transport materials include one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds.

7. A method for manufacturing a light-emitting device, characterized in that, It includes the following steps: Provide a light-emitting device preform, which includes a stacked cathode and a light-emitting layer; Deposit a polarized modified ferroelectric material on the light-emitting device preform to obtain a ferroelectric material layer; Fabricate an anode on the ferroelectric material layer to obtain a light-emitting device; Or, Provide a light-emitting device preform, which includes an anode; Deposit a polarized modified ferroelectric material on the light-emitting device preform to obtain a ferroelectric material layer; Fabricate a stacked light-emitting layer and cathode on the ferroelectric material layer to obtain a light-emitting device.

8. The manufacturing method according to claim 7, characterized in that, The depositing of the polarized modified ferroelectric material on the light-emitting device preform includes: Provide an unpolarized modified ferroelectric material, and deposit the unpolarized modified ferroelectric material on the light-emitting device preform in an electric field to form the polarized modified ferroelectric material.

9. The preparation method according to claim 8, wherein, The method of depositing the unpolarized modified ferroelectric material on the light-emitting device preform is the electrospinning method.

10. The preparation method according to claim 8, wherein, The deposition of the unpolarized modified ferroelectric material on the light-emitting device preform includes: dissolving the unpolarized modified ferroelectric material in a solvent to obtain an unpolarized modified ferroelectric material solution; depositing the unpolarized modified ferroelectric material solution on the light-emitting device preform by electrospinning in an electric field.

11. The preparation method according to claim 10, wherein, The unpolarized modified ferroelectric material includes an unpolarized modified organic ferroelectric material, and the unpolarized modified organic ferroelectric material includes one or more of unpolarized modified polyvinylidene fluoride, unpolarized modified vinylidene fluoride, unpolarized modified trifluoroethylene copolymer, and unpolarized modified polyurethane; and / or The solvent includes one or more of dimethyl sulfoxide, chloroform, and dimethylformamide; and / or The concentration of the unpolarized modified ferroelectric material solution is 1 to 10 wt%.

12. The preparation method according to claim 10, wherein, The direction of the electric field forms an angle of 45° to 90° with the light-emitting device preform; and / or The intensity of the electric field is 0.5 to 10 MV / m; and / or The ejection rate of the unpolarized modified ferroelectric material solution in the electrospinning is 0.05 to 5 mL / h; and / or The filament-forming voltage of the electrospinning is 5 to 15 kV; and / or The filament-forming spacing of the electrospinning is 1 to 3 nm.

13. A display device, wherein, A light-emitting device according to any one of claims 1 to 6.

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