Qled device and preparation method

Abstract

The application discloses a QLED device and a preparation method. The QLED device comprises an anode, a quantum dot light-emitting layer, an electron injection layer and a cathode which are sequentially stacked; wherein the forming material of the electron injection layer comprises a metal organic framework material, and the metal organic framework material has pores; and metal particles are filled in the pores. Thus, the problem of leakage current of the quantum dot light-emitting device is solved.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to a QLED device and its fabrication method. Background Technology

[0002] QLED devices are devices made based on the photoelectric effect. They have wide applications in new energy, sensing, communication, display, and lighting fields, such as solar cells, photodetectors, organic light-emitting devices (OLEDs) or quantum dot light-emitting devices (QLEDs).

[0003] In recent years, with the rapid development of display technology, quantum dot light-emitting devices (QLEDs), which use semiconductor quantum dot materials as the quantum dot emitting layer, have attracted widespread attention. The high color purity, high luminous efficiency, tunable emission color, and device stability of quantum dot LEDs make them promising for applications in flat panel displays, solid-state lighting, and other fields.

[0004] While the fabrication technology of quantum dot light-emitting devices is becoming increasingly mature, some drawbacks of quantum dot light-emitting devices cannot be ignored: quantum dot light-emitting devices are very prone to leakage current, which can lead to breakdown and quenching, resulting in damage to the quantum dot light-emitting devices.

[0005] There is an urgent need to develop a new technology that can reduce the probability of the quantum dot light-emitting device being quenched due to leakage current breakdown. Summary of the Invention

[0006] In view of this, this application provides a QLED device and a fabrication method, aiming to improve the leakage current problem of quantum dot light-emitting devices.

[0007] This application provides a QLED device, including an anode, a quantum dot light-emitting layer, an electron injection layer, and a cathode stacked sequentially; wherein, the electron injection layer is formed by a metal-organic framework material having pores; and metal particles filling the pores.

[0008] Optionally, the metal particles are of the same type as the metal material of the cathode.

[0009] Optionally, the particle size of the metal particles is 1 nm to 8 nm.

[0010] Optionally, the pore size of the metal-organic framework material is 2-3 nm, and the specific surface area is 3500-4000 m². 2 / g.

[0011] Optionally, the metal-organic framework material includes at least one of Ni-MOF magnetic nanomaterials, Fe-MOF magnetic nanomaterials, and Co-MOF magnetic nanomaterials; and / or the metal particles include at least one of silver particles or aluminum particles; and / or the cathode material includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg.

[0012] Optionally, the metal particles account for 3-18 wt% of the mass of the metal-organic framework material; and / or the thickness of the electron injection layer is 10 nm-15 nm; and / or the saturation magnetization of the electron injection layer is 25-40 emu / g.

[0013] Optionally, it further includes: a magnetic encapsulation layer covering the anode or the cathode, the magnetic encapsulation layer comprising: an organic matrix having pores; and magnetic particles filling the pores.

[0014] Optionally, the magnetic particles include a nanorod core and a magnetic shell covering the outer surface of the nanorod core. The nanorod core includes a silver nanorod core, and the magnetic shell includes at least one of magnetic ferrite material, magnetic nickel oxide material, and magnetic cobalt oxide material; and / or the organic matrix includes at least one of PVDF, epoxy resin, and polymethyl methacrylate; and / or the thickness of the magnetic encapsulation layer is 500 nm-2500 nm; and / or the saturation magnetization of the magnetic encapsulation layer is 70-80 emu / g.

[0015] Optionally, it also includes an electron transport layer disposed between the quantum dot light-emitting layer and the electron injection layer, wherein the electron transport layer is made of zinc oxide.

[0016] This application also provides a method for fabricating a QLED device, comprising the following steps: sequentially forming an anode, a quantum dot light-emitting layer, an electron injection layer, and a cathode stacked together; wherein, the electron injection layer is formed by a metal-organic framework material and metal particles, the metal-organic framework material having pores, and the metal particles filling the pores.

[0017] Optionally, the method may further include the following step: preparing a magnetic encapsulation layer over the cathode or the anode to form the target device.

[0018] Optionally, the method further includes: magnetizing the target device, wherein the magnetic field strength of the magnetization treatment is 0.1T-0.5T, the magnetization time is 0.5-4 hours, and the direction of the magnetic field includes at least the plane parallel to the electron injection layer.

[0019] Optionally, an electron transport layer is disposed between the quantum dot emitting layer and the electron injection layer. The electron injection layer is formed by the following steps: dispersing magnetic nanomaterials in a first organic solvent to form a first solution; adding metal ions to the first solution to form a second solution; centrifuging and drying the second solution to obtain a precipitate; reducing the precipitate to obtain a metal particle-metal-organic framework material; adding the metal particle-metal-organic framework material to a second organic solvent to form a third solution; and using the third solution to form a thin film on the side of the electron transport layer away from the quantum dot emitting layer and drying it to form the electron injection layer.

[0020] Optionally, the magnetic encapsulation layer is formed by the following steps: adding metal nanomaterials and magnetic materials to a third organic solvent to obtain a fourth solution; cooling and centrifuging the fourth solution to obtain a solid mixture; sintering the solid mixture to obtain magnetic core-shell nanoparticles; dispersing the magnetic core-shell nanoparticles into an organic matrix to form a fifth solution; using the fifth solution to form a thin film on the side of the cathode away from the quantum dot light-emitting layer or the side of the anode away from the quantum dot light-emitting layer and drying it to form the magnetic encapsulation layer.

[0021] Optionally, in the fifth solution, the mass percentage of the magnetic core-shell nanoparticles is 5-20 wt%, based on the total mass of the organic matrix.

[0022] In this embodiment, due to the provision of an electron injection layer, and the metal particles in the electron injection layer providing surface energy to repel holes, the Coulomb blocking effect makes it difficult for holes to enter the cathode, reducing the leakage current caused by hole injection into the cathode and lowering the probability of the quantum dot light-emitting device being damaged due to leakage current. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a QLED device in one embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the structure of a QLED device in one embodiment of this application;

[0026] Figure 3 This is a schematic flowchart of the fabrication method of a QLED device in one embodiment of this application;

[0027] Figure 4 This is a schematic flowchart illustrating the steps for preparing the electron injection layer in one embodiment of this application;

[0028] Figure 5 This is a schematic flowchart illustrating the steps involved in preparing the magnetic encapsulation layer in one embodiment of this application. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of the present invention 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 conciseness and should not be construed as a hard limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within that range. For example, it should be assumed that the description of a range from 1 to 6 specifically discloses subranges 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0030] Research has found that a key reason why quantum dot light-emitting devices are prone to quenching due to leakage current in existing technologies is that zinc oxide thin films are commonly used as the electron transport layer. While zinc oxide films have good conductivity, which is very conducive to electron transport to the quantum dot light-emitting layer, there are Zn-OH (terminal hydroxyl surface) oxygen vacancy defects in the zinc oxide electron transport layer. These defects have energy levels of 5.5 eV-6.5 eV, which are consistent with the HOMO energy levels of the hole transport layer in quantum dot light-emitting devices. Therefore, during use, excessive holes in the hole transport layer can penetrate through the defect states of the electron transport layer, thereby forming leakage current and causing device quenching.

[0031] Therefore, this application proposes a QLED device that uses an electron injection layer to prevent and reduce the number of holes injected into the cathode of the QLED device, thereby improving the stability of the QLED device. The quantum dot light-emitting device also belongs to the category of QLED devices; therefore, this electron injection layer can also improve the stability of the quantum dot light-emitting device.

[0032] One embodiment of this application provides a QLED device.

[0033] Please see Figure 1 This is a schematic diagram of the structure of a QLED device in one embodiment of this application.

[0034] In this embodiment, the QLED device includes an anode 103, a quantum dot light-emitting layer 108, an electron injection layer 101, and a cathode 107 stacked sequentially; wherein, the electron injection layer 101 is formed by a metal-organic framework material having pores; and metal particles filling the pores.

[0035] The QLED device further includes a substrate 100 and an electron transport layer 106. The cathode 107 is disposed on the substrate 100, forming an inverted QLED device, or the anode 103 is disposed on the substrate 100, forming a normal QLED device. The electron transport layer 106 is disposed between the quantum dot light-emitting layer 108 and the electron injection layer 101, and the material of the electron transport layer 106 is zinc oxide.

[0036] The electron injection layer 101 is located between the electron transport layer 106 and the cathode 107, and is used to provide a path for electron transport. The metal particles in the electron injection layer 101 can provide surface energy to repel the holes, thereby reducing the number of holes injected into the cathode 107.

[0037] In this embodiment, the metal particles in the electron injection layer 101 provide surface energy to repel holes, and the Coulomb blocking effect makes it difficult for holes to enter the cathode 107, reducing leakage current caused by hole injection into the cathode 107 and lowering the probability of damage to the quantum dot light-emitting device due to leakage current. Furthermore, the electron injection layer 101 can also block metal diffusion between the cathode 107 and the electron transport layer 106.

[0038] In some embodiments, the pore size of the metal-organic framework material is 2-3 nm, and the specific surface area is 3500-4000 m². 2 / g. In fact, the pore size, porosity, and specific surface area of ​​the pores are related to the target type and preferred size of the metal particles.

[0039] In some embodiments, the smaller the particle size of the metal particles, the greater the surface energy and the stronger the hole repulsion ability. Typically, the particle size of the metal particles is set between 1 nm and 8 nm. While larger particle sizes result in better conductivity, excessively large particle sizes can affect the surface energy of the metal particles, thereby impacting the hole repulsion ability of the electron injection layer 101. Conversely, excessively small particle sizes can negatively affect the conductivity of the electron injection layer 101.

[0040] In some embodiments, the metal particles constitute 3–18 wt% of the metal-organic framework material. The mass percentage of the metal particles in the metal-organic framework material affects the conductivity and hole repulsion of the electron injection layer 101. Specifically, the higher the mass percentage of the metal particles in the metal-organic framework material, the stronger the conductivity and hole repulsion of the electron injection layer 101, and vice versa.

[0041] In some embodiments, the metal-organic framework material includes at least one of Ni-MOF magnetic nanomaterials, Fe-MOF magnetic nanomaterials, and Co-MOF magnetic nanomaterials. Other types of metal-organic framework materials may be selected as needed, but magnetic nanomaterials are preferred. Magnetic nanomaterials allow the metal-organic framework material to acquire magnetism under the influence of a magnetic field, which helps to promote electron transport rates.

[0042] MOFs (Metal-Organic Frameworks) are organic-inorganic hybrid materials with intramolecular pores formed by the self-assembly of organic ligands and metal ions or clusters through coordination bonds. They are coordination polymers with a three-dimensional porous structure. Generally, metal ions serve as connection points, while organic ligands provide support to form a 3D spatial extension. They are another important new type of porous material besides zeolites and carbon nanotubes, and have wide applications in catalysis, energy storage, and separation.

[0043] In some embodiments, the Ni-MOF magnetic nanomaterials, Fe-MOF magnetic nanomaterials, and Co-MOF magnetic nanomaterials are all magnetic nanosheets.

[0044] In some embodiments, the structural formula of the Ni-MOF magnetic nanomaterial is shown in formula (1) below:

[0045]

[0046] In some embodiments, the structural formula of the Fe-MOF magnetic nanomaterial is shown in formula (2) below:

[0047]

[0048] In some embodiments, the structural formula of the Co-MOF magnetic nanomaterial is shown in formula (3) below:

[0049]

[0050] In some embodiments, the quantum dot light-emitting device is a quantum dot electroluminescent diode, and the electron injection layer 101 is provided with the magnetic nano-metal-organic framework material. After the quantum dot light-emitting device is magnetized in a magnetic field, under the action of the Lorentz force, the electron transport efficiency in the quantum dot light-emitting device is higher, and electrons can be injected into the quantum dot light-emitting layer 108 more quickly, thereby improving the luminous efficiency of the quantum dot light-emitting device.

[0051] In this embodiment, the thickness of the electron injection layer 101 is approximately 10 nm to 15 nm. The electron injection layer 101 is a fully magnetized electron injection layer 101, and the saturation magnetization of the electron injection layer 101 is 25 emu / g to 40 emu / g.

[0052] In some specific embodiments, the saturation magnetization of the electron injection layer 101 is related to the metal-organic framework material. When the metal-organic framework material is Ni-MOF, the corresponding saturation magnetization of the electron injection layer 101 is 30 emu / g; when the metal-organic framework material is Fe-MOF, the corresponding saturation magnetization of the electron injection layer 101 is 42 emu / g; and when the metal-organic framework material is Co-MOF, the corresponding saturation magnetization of the electron injection layer 101 is 35 emu / g.

[0053] The electron injection layer 101 can be prepared by preparing a corresponding metal particle-magnetic nanoparticle ink and printing the ink onto the upper surface of the electron transport layer 106.

[0054] In one embodiment, the anode 103 is located near the quantum dot light-emitting layer 108; the cathode 107 is located near the electron transport layer 106.

[0055] The anode 103 can be any material known in the art for QLED anodes, such as one or more of metals, carbon materials, and metal oxides. Metals can be, for example, one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg; carbon materials can be, for example, one or more of graphite, carbon nanotubes, graphene, and carbon fibers; and metal oxides can be doped or undoped metal oxides, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO. This also includes composite electrodes consisting of a metal sandwiched between doped or undoped transparent metal oxides. These composite electrodes include, but are not limited to, one or more of the following: 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, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2. The thickness of the anode 10310 can be, for example, from 10 nm to 200 nm, such as 10 nm, 50 nm, 80 nm, 120 nm, 150 nm, 200 nm, etc.

[0056] The cathode 107 can be a QLED cathode 107 material known in the art, and the metal electrode is desired in this embodiment. For example, the cathode 107 material can be one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg. In some embodiments, in order to form a good material match and reduce interface voids, the metal material used for the cathode 107 is selected from the same type of metal particles in the electron injection layer 101.

[0057] In fact, metal oxide electrodes, composite electrodes, and carbon materials can also be used, but the electron injection layer 101 and the encapsulation layer are designed for metal electrodes, so replacing them with other types of electrodes will not achieve the best results.

[0058] In some embodiments, the cathode 107 is a silver electrode, the metal particles are silver particles, and the particle size of the silver particles is 2 mm to 6 mm. In some embodiments, the mass percentage of the silver particles in the metal-organic framework material ranges from 5 wt% to 15 wt%. In some other embodiments, the mass percentage of the metal particles in the metal-organic framework material ranges from 3 wt% to 18 wt%, and can actually be set as needed, such as 3 wt%, 5 wt%, 10 wt%, 15 wt%, 18 wt%, etc. In other embodiments, the cathode 107 can also be an aluminum electrode, etc. In the above embodiments, when the cathode 107 is an aluminum electrode, the metal particles are aluminum particles to achieve a better material matching effect with the aluminum electrode.

[0059] In these embodiments, the surface energy of the metal particles in the electron injection layer 101 can repel the holes, enabling a Coulomb blocking effect and generating a Coulomb repulsion force to prevent holes from passing through the electron transport layer 106 to form a leakage current, thereby improving the device stability of the quantum dot light-emitting diode.

[0060] The electron transport layer 106 can be composed of inorganic and / or organic materials. Inorganic materials include, but are not limited to, undoped or doped metal / non-metal oxides (e.g., TiO2, ZnO, ZrO, SnO2, WO3, Ta2O3, HfO3, Al2O3, ZrSiO4, BaTiO3, and BaZrO3) of aluminum (Al), magnesium (Mg), indium (In), lithium (Li), gallium (Ga), cadmium (Cd), cesium (Cs), or copper (Cu). When organic materials are used, they can be composed of materials such as… azole compounds, isoazoles azole compounds, triazole compounds, isothiazole compounds, Organic materials such as diazole compounds, thiadiazole compounds, perylene compounds, or aluminum complexes are used to form the electron transport layer 10670. In some embodiments, the material of the electron transport layer 10670 is N-type doped ZnO. The thickness of the electron transport layer 106 can be 50 nm to 150 nm, preferably 10 nm to 60 nm. The electron transport layer 106 has two main functions: firstly, it forms a small potential barrier with the cathode 107, which is beneficial for electron injection; secondly, it can effectively block holes and prevent leakage current. When selecting the material of the electron transport layer 106, it is necessary to ensure that the lowest unoccupied molecular orbital (LUMO) energy level of the material matches the work function of the cathode 107, while having a high electron mobility to enable effective electron injection.

[0061] In some embodiments, the material of the quantum dot light-emitting layer 108 comprises quantum dots. The thickness of the quantum dot light-emitting layer 108 can be within the thickness range of quantum dot light-emitting layers 108 in conventional quantum dot light-emitting devices, for example, it can be 10 nm to 60 nm, such as 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 40 nm, 50 nm, 60 nm, etc., or the thickness of the quantum dot light-emitting layer 108 can be 10-25 nm. The material of the quantum dot light-emitting layer 108 is a quantum dot known in the art for use in the quantum dot light-emitting layer 108, for example, one of red quantum dots, green quantum dots, and blue quantum dots. The quantum dots can be selected from, but are not limited to, at least one of single-structure quantum dots and core-shell structure quantum dots. For example, single-structure quantum dots can be selected from, but are not limited to, one or more of group II-VI compounds, group III-V compounds, and group I-III-VI compounds. As an example, group II-VI compounds may be selected from, but are not limited to, one or more of CdSe, CdS, CdTe, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS; CdZnSeS, CdZnSeTe, and CdZnSTe; group III-V compounds may be selected from, but are not limited to, one or more of InP, InAs, GaP, GaAs, GaSb, AlN, AlP, InAsP, InNP, InNSb, GaAlNP, and InAlNP; and group I-III-VI compounds may be selected from, but are not limited to, one or more of CuInS2, CuInSe2, and AgInS2. The core of the core-shell quantum dot is selected from any one of the single-structure quantum dots mentioned above, and the shell material of the core-shell quantum dot is selected from at least one of CdS, CdTe, CdSeTe, CdZnSe, CdZnS, CdSeS, ZnSe, ZnSeS and ZnS.

[0062] In one embodiment, the quantum dot light-emitting device further includes a hole transport layer 105 (HTL). The hole transport layer 105 is disposed between the anode 103 and the quantum dot light-emitting layer 108. The material of the hole transport layer 105 can be selected from organic materials with hole transport capabilities, including but not limited to poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCATA), 4,4'-bis(9-carbazole)biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4 The hole transport layer may be selected from one or more of the following: 1-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), doped graphene, undoped graphene, and C60. The hole transport layer material may also be selected from inorganic materials with hole transport capabilities, including but not limited to one or more of doped or undoped NiO, WO3, MoO3, and CuO. The thickness of the hole transport layer is the same as that of a conventional hole transport layer, for example, it can be from 10 nm to 100 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 100 nm, etc. Alternatively, the thickness of the hole transport layer can range from 20 to 60 nm.

[0063] In one embodiment, the QLED device may further include a hole injection layer 104, which is located on the surface of the anode 103 facing the cathode 107. When the QLED device includes both a hole injection layer 104 and a hole transport layer 105, the hole injection layer 104 is located between the anode 103 and the hole transport layer 105; while when the QLED device includes a hole injection layer but does not include a hole transport layer, the hole injection layer is located between the anode 103 and the quantum dot light-emitting layer 108. In both of these different cases, the hole injection layer is located on the surface of the anode 103 facing the cathode 107 and is in contact with the anode 103. The material of the hole injection layer is a material known in the art for hole injection layers. The material can be selected from materials with hole injection capability, including but not limited to poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinone-dimethylethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzphenanthrene (HATCN), copper polyester carbonate (CuPc), transition metal oxides, and transition metal chalcogenides. The thickness of the hole injection layer can be the thickness of a conventional hole injection layer, for example, it can be 30 nm to 50 nm, such as 30 nm, 40 nm, 50 nm, etc.

[0064] Please see Figure 2 This is a schematic diagram of the structure of the QLED device in another embodiment.

[0065] In this embodiment, the QLED device further includes a magnetic encapsulation layer 102, which covers the anode 103 or the cathode 107. Specifically, the QLED device can be a forward-facing device or an inverted device. When it is a forward-facing device, with the anode 103 disposed on the substrate 100, the magnetic encapsulation layer 102 is disposed above the cathode 107, at least for encapsulating the upper surface of the cathode 107, the electron injection layer 101, and the electron transport layer 106. When it is an inverted device, with the cathode 107 disposed on the substrate 100, the magnetic encapsulation layer 102 is disposed above the anode 103, at least for encapsulating the upper surface of the anode 103.

[0066] In some embodiments, the thickness of the magnetic encapsulation layer 102 is 500nm-2500nm. The greater the thickness of the magnetic encapsulation layer 102, the better the water and oxygen isolation performance of the QLED device. The magnetic encapsulation layer 102 is a fully magnetized magnetic encapsulation layer 102, and the saturation magnetization of the magnetic encapsulation layer 102 is 70-80 emu / g.

[0067] The magnetic encapsulation layer 102 can at least isolate the cathode 107, electron injection layer 101, and electron transport layer 106 from external water and oxygen, or isolate the anode 103 from external water and oxygen, thereby improving the device's performance and lifespan. Furthermore, because a magnetic encapsulation layer 102 is used, it can be used... Figure 2 The magnet 200 shown magnetizes the magnetic nano-metal-organic framework material in the magnetic encapsulation layer 102 and the electron injection layer 101, thereby utilizing the magnetism of the magnetic encapsulation layer 102 and the electron injection layer 101 to promote electron injection and transport, thereby improving luminescence efficiency.

[0068] In some embodiments, the magnetic encapsulation layer 102 includes: an organic matrix having pores; and magnetic particles filling the pores.

[0069] In some embodiments, the magnetic particle includes a nanorod core and a magnetic shell covering the outer surface of the nanorod core.

[0070] In some embodiments, the cathode 107 comprises silver, the nanorod core comprises silver nanorod cores, and the magnetic shell comprises at least one of a magnetic ferrite shell, a magnetic nickel-oxygen shell, and a magnetic cobalt-oxygen shell. The magnetic ferrite shell comprises Fe2O3, the magnetic nickel-oxygen shell comprises NiO2, and the magnetic chromium-oxygen shell comprises Co2O3. In these embodiments, the cathode 107 and the nanorod core are made of the same metal, which enables good material matching, reduces the interfacial voids between the cathode 107 and the magnetic encapsulation layer 102, and better blocks the penetration of water and oxygen.

[0071] In some embodiments, the thickness of the magnetic encapsulation layer 102 is 1000nm-2000nm, and it can be prepared by coating. At this thickness, the magnetic encapsulation layer 102 can better block the penetration of water and oxygen.

[0072] In some embodiments, the organic matrix includes at least one of PVDF, epoxy resin, and polymethyl methacrylate.

[0073] The embodiments of this application also provide a method for fabricating a QLED device.

[0074] Please see Figure 3 This is a schematic diagram of the steps of the preparation method described in one embodiment.

[0075] In this embodiment, the preparation method includes the following steps:

[0076] Step S301: Sequentially forming an anode, a quantum dot light-emitting layer, an electron injection layer, and a cathode stacked together; wherein, the electron injection layer is formed by a metal-organic framework material and metal particles, the metal-organic framework material has pores, and the metal particles fill the pores.

[0077] In some embodiments, the preparation method is in Figure 3 Based on step S301 shown, the following further steps are included: preparing a magnetic encapsulation layer above the cathode or the anode to form the target device.

[0078] This is because the QLED includes upright QLEDs and inverted QLEDs. In an inverted QLED, the cathode is disposed on the substrate 100, and the anode 103 is disposed outwards, in which case a magnetic encapsulation layer is formed above the anode 103. In an upright QLED, the anode 103 is disposed on the substrate 100, and the cathode is disposed outwards, thereby forming the magnetic encapsulation layer above the cathode.

[0079] Furthermore, in some embodiments, when the magnetic encapsulation layer is formed above the cathode, the magnetic encapsulation layer at least covers the upper surface of the cathode; when the magnetic encapsulation layer is formed above the anode, the magnetic encapsulation layer at least covers the upper surface of the anode.

[0080] Please see Figure 2 This is a schematic diagram of the structure when a magnetic encapsulation layer is fabricated above the cathode in one embodiment. The magnetic encapsulation layer not only covers the upper surface of the cathode, but also covers the sidewall surfaces of other layers of the QLED, as well as the upper surface of the substrate 100.

[0081] In fact, the coverage area of ​​the magnetic encapsulation layer can be set as needed.

[0082] In some embodiments, the method further includes: magnetizing the target device, wherein the magnetic field strength of the magnetization process is 0.1T-0.5T, the magnetization time is 0.5-4 hours, and the direction of the magnetic field includes at least the plane parallel to the electron injection layer.

[0083] In some embodiments, a first magnetic field is parallel to the surface of the device, and the magnetic field strength is 0.3T. The prepared device is placed in the first magnetic field for aging for 10 to 30 minutes, so that the magnetic material in the device is magnetized and has a certain magnetism. Then, due to the Lorentz force, electrons are further injected into the quantum dot light-emitting layer 108, improving the device efficiency. Furthermore, since the device aging is carried out in the magnetic field, the damage to the functional layer of the device during high-temperature aging is reduced, and the stability of the device is improved.

[0084] Please see Figure 4This is a schematic diagram of the steps for preparing the electron injection layer in one embodiment.

[0085] In this embodiment, an electron transport layer is disposed between the quantum dot light-emitting layer and the electron injection layer, and the electron injection layer is formed by the following steps:

[0086] Step S401: Disperse the magnetic nanomaterials in a first organic solvent to form a first solution;

[0087] Step S402: Add metal ions to the first solution to form a second solution;

[0088] Step S403: Centrifuge and dry the second solution to obtain a precipitate;

[0089] Step S404: The precipitate is subjected to reduction treatment to obtain metal particle-metal-organic framework material;

[0090] Step S405: Add the metal particle-metal-organic framework material to the second organic solvent to form a third solution;

[0091] Step S406: A thin film is formed on the side of the electron transport layer away from the quantum dot light-emitting layer using a third solution and then dried to form the electron injection layer.

[0092] In some embodiments, the magnetic nanomaterial includes at least one of Ni-MOF nanomaterials, Fe-MOF nanomaterials, and Co-MOF nanomaterials; the metal particles are of the same type as the metal material used in the cathode.

[0093] When the cathode is silver, the metal particles are silver particles. When the cathode is aluminum, the metal particles are aluminum particles. Maintaining consistency between the type of metal material used in the metal particles and the cathode ensures good material matching and reduces interfacial voids between the cathode and the electron injection layer.

[0094] In some embodiments, the silver particles have a particle size of 2 mm to 6 mm. In practice, the particle size of the metal particles is related to the type of metal material used, as well as the required surface energy and conductivity. In some embodiments, the particle size of the metal particles is generally between 1 nm and 8 nm. Furthermore, the smaller the particle size, the greater the surface energy the metal particles can provide, the stronger the repulsion force against holes, the stronger the ability to prevent holes from transmitting to the cathode and forming leakage current, and the stronger the stability of the quantum dot light-emitting device. The larger the particle size, the stronger the conductivity of the electron injection layer.

[0095] In some embodiments, the metal particles have a particle size of 1 nm, which provides a larger surface energy, resulting in a stronger repulsive force against holes. In other embodiments, the metal particles have a particle size of 8 nm, leading to stronger conductivity of the electron injection layer.

[0096] In one embodiment, the metal particles are silver particles, and the magnetic nanomaterial is Ni-MOF. During the preparation of the electron injection layer, step S401 specifically involves: adding 100 mg of Ni MOF nanosheets to 40 ml of a first organic solvent and ultrasonically dispersing for 30 min to form the first solution. The Ni MOF nanosheets are the magnetic nanomaterial, and the first organic solvent is n-hexane.

[0097] Step S402 specifically involves adding silver nitrate to the first solution in a certain proportion to form the second solution. Specifically, if the Ni MOF nanosheets are required to contain 5 wt% Ag, then 8 mg of silver nitrate needs to be added to the first solution; if the Ni MOF nanosheets are required to contain 10 wt% Ag, then 16 mg of silver nitrate needs to be added to the first solution; if the Ni MOF nanosheets are required to contain 15 wt% Ag, then 24 mg of silver nitrate needs to be added to the first solution, with the silver nitrate providing the metal ions.

[0098] In some embodiments, step S403 may be: ultrasonically dispersing the second solution for at least 3 hours and centrifuging and drying for 12 hours to obtain a precipitate.

[0099] In some embodiments, step S404 may be: pouring 5 ml / 0.6 mol of NaBH4 aqueous solution into the precipitate to reduce the precipitate, and allowing the NaBH4 to react with the precipitate for at least 30 min to 60 min, and then centrifuging and washing the reactants to obtain Ag particles / Ni-MOF as a mixture of metal particles and magnetic nanoparticles.

[0100] In some embodiments, step S405 may be: dissolving a mixture of metal particles and magnetic nanoparticles in n-hexane, wherein the n-hexane serves as the second organic solvent, to prepare a third solution at a concentration of 6 mg / ml, which can be used as ink to achieve the printing function.

[0101] In some embodiments, step S406 may be: printing an electron injection layer film with a thickness of 10nm-15nm on the upper surface of the electron transport layer by inkjet printing, thereby applying the third solution to the upper surface of the electron transport layer to form the electron injection layer.

[0102] In these embodiments, the drying process in step S406 includes: placing the device to which the third solution has been applied into a vacuum dryer for vacuum drying, so that the third solution solidifies to form the electron injection layer.

[0103] In some embodiments, the magnetic nanomaterials used in steps S401 to S406 may be at least one of Fe-MOF magnetic nanomaterials and Co-MOF magnetic nanomaterials. In this case, the specific materials in steps S401 to S406 may be changed as needed.

[0104] Please see Figure 5 This is a schematic diagram of the steps for preparing the magnetic encapsulation layer in one embodiment.

[0105] In this embodiment, the preparation of the magnetic encapsulation layer includes at least the following steps:

[0106] Step S501: Add the metal nanomaterial and the magnetic material to the third organic solvent to obtain the fourth solution;

[0107] Step S502: Cool and centrifuge the fourth solution to obtain a solid mixture;

[0108] Step S503: Sinter the solid mixture to obtain magnetic core-shell nanoparticles;

[0109] Step S504: Disperse the magnetic core-shell nanoparticles into an organic matrix to form a fifth solution;

[0110] Step S505: Using the fifth solution, a thin film is formed on the side of the cathode away from the quantum dot light-emitting layer or the side of the anode away from the quantum dot light-emitting layer, and then dried to form the magnetic encapsulation layer.

[0111] In some embodiments, the magnetic core-shell nanoparticles in the fifth solution are 5-20 wt% based on the total mass of the organic matrix.

[0112] In some embodiments, the cathode comprises a silver electrode, the metal nanomaterial comprises silver nanorods, and the magnetic material comprises at least one of iron phosphate and nickel acetate.

[0113] Maintaining the same type of metal nanomaterial as the metal material used in the cathode can ensure good material matching between the cathode and the magnetic encapsulation layer, reducing the interface gap between the cathode and the magnetic encapsulation layer.

[0114] In one embodiment, the metal particles are silver particles, the metal nanomaterials are silver nanorods, and the magnetic material is iron phosphate. In the preparation of the magnetic encapsulation layer, step S501 specifically involves: adding a certain amount of silver nanorods and iron phosphate to a formic acid solution, wherein the molar ratio of silver nanorods to iron phosphate is 1:3-1:5, and the formic acid is a third organic solvent; then stirring the mixture at 70°C for 2 hours to obtain the fourth solution.

[0115] Step S502 specifically involves: cooling and centrifuging the fourth solution to obtain a solid mixture, and then sintering the solid mixture at 450°C for 2 hours to obtain magnetic core-shell nanoparticles composed of Ag@Fe2O3.

[0116] Step S503 specifically involves dispersing magnetic core-shell nanoparticles composed of Ag@Fe2O3 into an organic matrix, wherein the organic matrix is ​​PVDF (poly(1,1-difluoroethylene)), and the addition amount is 5wt%-20wt%. The mixture is then stirred at 60°C for 2 hours to form the fifth solution.

[0117] Step S504 specifically involves: dissolving the fifth solution in a DMF (N,N-Dimethylformamide) solution to prepare a 60 mg / ml ink, and applying the fifth solution to the upper surface of the cathode by printing, thereby printing a magnetic encapsulation layer with a thickness of 1000 nm-2000 nm on the upper surface of the cathode.

[0118] In some embodiments, after the fifth solution forms a thin film on the side of the cathode away from the quantum dot light-emitting layer or the side of the anode away from the quantum dot light-emitting layer, the device can be placed in a vacuum dryer to perform vacuum drying on the thin film.

[0119] In some other embodiments, when the magnetic material is nickel acetate, the magnetic encapsulation layer can be prepared using the following steps: 0.15 g of silver nanorods and 0.61 g of nickel acetate are dissolved in 12 ml of distilled water, sonicated for 20 min to mix evenly, then 12 ml of NaOH is added, and the mixture is reacted at 170 °C for 10 h. After the reaction is complete, the precipitate is obtained by centrifugation, washed with ethanol, and dried to obtain magnetic core-shell nanoparticles composed of Ag@NiO2. The Ag@NiO2 magnetic core-shell nanoparticles are then dispersed in an organic PVDF matrix at an addition amount of 5 wt%-20 wt%, stirred at 60 °C for 2 h, and the mixture is then dissolved in DMF solution to prepare a 60 mg / ml ink, which is then printed into a magnetic encapsulation layer with a diameter of 1000 nm-2000 nm.

[0120] Example 1:

[0121] The structure of a quantum dot light-emitting device is as follows: an ITO substrate, a hole injection layer 104 made of PEDOT:PSS material with a thickness of 50 nm on the upper surface of the ITO substrate, a hole transport layer made of poly-TPD material with a thickness of 30 nm on the upper surface of the hole injection layer 104, a red quantum dot light-emitting layer 108 with a thickness of 20 nm on the upper surface of the hole transport layer (usually adopting a CdSe / CdS core-shell structure, the size of the CdSe / CdS core-shell is generally between 12 and 20 nm), an electron transport layer made of ZnO material with a thickness of 30 nm on the upper surface of the red quantum dot light-emitting layer 108, an electron injection layer made of Ag particles / Ni-MOF hybrid nanosheets with a thickness of 15 nm on the upper surface of the electron transport layer, a silver cathode with a thickness of 70 nm on the upper surface of the electron injection layer, and a magnetic encapsulation layer with a thickness of 2000 nm on the upper surface of the cathode.

[0122] To prepare the electron injection layer, 100 mg of Ni-MOF nanosheets were first added to 20 ml of n-hexane solvent and ultrasonically dispersed for 30 min. Then, based on the 5 wt% Ag content of the Ni-MOF nanosheets, 0.8 ml of silver nitrate solution was added, and the mixture was ultrasonically treated for 3 h. After centrifugation and drying for 12 h, a precipitate was obtained. 5 ml / 0.6 mol NaBH4 aqueous solution was added to the precipitate and reacted for 30 min to obtain silver particles with a diameter of 3 nm. The reactants were then centrifuged and washed to obtain Ag particles / Ni-MOF. The Ag particles / Ni-MOF were then dissolved in n-hexane to prepare a 6 mg / ml ink. Six drops were printed, and the solvent was removed to obtain a 15 nm thick electron injection layer film.

[0123] A 70 nm thick silver electrode was prepared by silver vapor deposition.

[0124] In preparing the magnetic encapsulation layer, 1g of silver nanorods and 1.45g of ferric phosphate were added to 100ml of formic acid solution, and then stirred at 70℃ for 2h. The solution was cooled and centrifuged to obtain powder, and then the powder was sintered at 450℃ for 2h to obtain magnetic core-shell nanoparticles composed of Ag@Fe2O3. The magnetic core-shell nanoparticles composed of Ag@Fe2O3 were then dispersed into 0.076g of organic matrix such as PVDF (polyvinylidene fluoride) organic matrix, with the PVDF addition amount being 5%. The mixture was stirred at 60℃ for 2h, and then the mixture was dissolved in DMF solution to prepare 60mg / ml ink. Ten drops were then printed to form a 2000nm encapsulation film.

[0125] After the magnetic encapsulation layer is prepared, the device is aged in a 0.3T horizontal magnetic field for 30 minutes, with the ITO substrate placed horizontally.

[0126] Example 2:

[0127] The difference between this embodiment 2 and the above embodiment 1 is that the structure of the quantum dot light-emitting device is slightly different, so that the electron injection layer can be used for quantum dot light-emitting devices with various different structures.

[0128] In this embodiment 2, the quantum dot light-emitting device has an Ag reflective layer formed on the upper surface of an ITO substrate, an ITO anode 103 formed on the upper surface of the reflective layer, and a hole injection layer 104 made of PEDOT:PSS material with a thickness of 50 nm on the upper surface of the anode 103. Furthermore, the silver cathode has a thickness of 30 nm, and the electron injection layer has a thickness of 10 nm.

[0129] Therefore, when using the silver vapor deposition method, a silver electrode with a thickness of 30 nm needs to be prepared.

[0130] Furthermore, in preparing the electron injection layer, after configuring the ink to 6 mg / ml, 4 drops were printed, and the solvent was removed to obtain an electron injection layer film with a thickness of 10 nm.

[0131] After the magnetic encapsulation layer is prepared, the device is placed in a 0.3T horizontal magnetic field line for 30 minutes for aging, with the ITO substrate placed horizontally.

[0132] Example 3:

[0133] The difference between this embodiment 3 and the above embodiment 1 is that the thickness of the electron injection layer of the quantum dot light-emitting device is 10 nm and the thickness of the magnetic encapsulation layer is 1000 nm.

[0134] In this embodiment, compared to embodiment 1, when preparing the electron injection layer, after configuring the ink to 6 mg / ml, 4 drops were printed, and the solvent was removed to obtain an electron injection layer film with a thickness of 10 nm.

[0135] In preparing the magnetic encapsulation layer, after configuring the ink to 60 mg / ml, 6 drops were printed to form a 1000 nm magnetic encapsulation layer.

[0136] After the magnetic encapsulation layer is prepared, the device is placed in a 0.3T horizontal magnetic field line for 30 minutes for aging, with the ITO substrate placed horizontally.

[0137] Example 4:

[0138] The difference between this embodiment 4 and the above embodiment 1 is that the thickness of the electron injection layer of the quantum dot light-emitting device is 10 nm, the diameter of the silver particles is 6 nm, and the thickness of the magnetic encapsulation layer is 1000 nm.

[0139] In this embodiment, compared to embodiment 1, in preparing the electron injection layer, 100 mg of NiMOF nanosheets were first added to 20 ml of n-hexane solvent and ultrasonically dispersed for 30 min. Then, 2.4 ml of silver nitrate solution was added, and the mixture was ultrasonically treated for 3 h according to the Ni-MOF nanosheets containing 15 wt% Ag content. The mixture was then centrifuged and dried for 12 h to obtain a precipitate. 5 ml / 0.6 mol NaBH4 aqueous solution was added to the precipitate and reacted for 60 min to achieve a silver particle diameter of 6 nm. The reactants were then centrifuged and washed to obtain Ag particles / Ni-MOF. This Ag particles were then dissolved in n-hexane to prepare a 6 mg / ml ink solution. Four drops were printed, and the solvent was removed to obtain a 10 nm thick electron injection layer film.

[0140] In preparing the magnetic encapsulation layer, after configuring the ink to 60 mg / ml, 6 drops were printed to form a 1000 nm magnetic encapsulation layer.

[0141] After the magnetic encapsulation layer is prepared, the device is placed in a 0.3T horizontal magnetic field line for 30 minutes for aging, with the ITO substrate placed horizontally.

[0142] Comparative example:

[0143] Two standard samples are provided below, and their properties are compared:

[0144] Standard sample one includes ITO substrate / PEDOT: PSS (50nm) / poly-TPD (30nm) / red quantum dot emitting layer (20nm) / ZnO (30nm) / silver (70nm) / cover plate packaging.

[0145] Standard Sample 2: The structure of the electronic device is as follows: ITO substrate / PEDOT:PSS (50nm) / poly-TPD (30nm) / red quantum dot light-emitting layer (20nm) / ZnO (30nm) / silver (70nm) / silicon dioxide (2000nm).

[0146] The quantum dot light-emitting devices formed in Examples 1 to 4 and the standard samples described therein can be used to test water and oxygen permeability.

[0147] When testing the water and oxygen permeability of the encapsulation film, a mass spectrometer can be used. The testing method mainly involves introducing water into one side of the encapsulation film, while maintaining a high vacuum on the other side of the encapsulation film and connecting it to a mass spectrometer. The mass spectrometer captures the gas molecules that permeate through the film surface and calculates the molecular weight to obtain the water and oxygen permeability.

[0148] Table 1 is provided below, in which water vapor transmission rate is expressed as water oxygen transmission rate. Furthermore, the water oxygen transmission rate obtained in Table 1 is for different encapsulation films with a thickness of 2000 nm. Therefore, standard sample 2 and the encapsulation film in Example 1 are selected here.

[0149] Table 1: Comparison of water and oxygen permeability of different encapsulation films with a thickness of 2000 nm

[0150] serial number Water vapor transmission rate (g / m2 / day) Example 1 Encapsulation film 1.2*10-4 Example 2 Encapsulation Film 1.31*10-4 Example 3 Encapsulation film 1.45*10-4 Example 4 Encapsulation film 1.5*10-4 Standard sample encapsulation film 1.9*10-4

[0151] Water and oxygen permeability tests were conducted on the encapsulation films in Examples 2, 3, and 4. Since the thickness of the encapsulation film is 1000 nm, the water and oxygen permeability in Examples 2, 3, and 4 is slightly worse. The measured water vapor permeability of the encapsulation films in Examples 2, 3, and 4 are 1.13*10-4 g / m2 / day, 1.15*10-4 g / m2 / day, and 1.09*10-4 g / m2 / day, respectively.

[0152] Table 2: Comparison of device efficiency and decay rate of quantum dot light-emitting devices obtained from different embodiments and standard samples.

[0153] Device Number EQE LT95@1000nit(h) First Specific Implementation 10.1％ 13000 Third Specific Implementation 9.8％ 12510 Fourth Detailed Implementation 10.5％ 12000 Standard Sample 1 10.6％ 5660 Standard Sample Two 10.8％ 8230

[0154] Here, EQE is the ratio of excitons to photons in the device, which is usually used to characterize the device's efficiency. The higher the EQE, the higher the device efficiency. LT95@1000Nit refers to the time required for the device to decay to 950Nit brightness from an initial brightness of 1000 nits. The lifetime here is tested after 21 days of storage.

[0155] Since Example 2 is a top-emitting device, and its device structure differs from the other examples and standard samples, it is not listed in Table 2 for comparison with other examples or standard samples. Experimentally, Example 2 achieved an EQE of 15.5% and an LT95@1000nit value of 12860h.

[0156] As shown in the table above, after adopting the magnetic encapsulation layer in the specific embodiment of this application, the aging speed of the quantum dot light-emitting device is much slower than that of standard sample one and standard sample two, and the device efficiency is higher. Furthermore, the magnetic encapsulation layer in the first specific embodiment can effectively reduce water vapor transmission rate.

[0157] The above provides a detailed description of the electron transmission thin film and its preparation method, the QLED device and its preparation method, and the display device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the methods and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A QLED device, characterized in that, include: The anode, quantum dot light-emitting layer, electron transport layer, electron injection layer, and cathode are stacked in sequence. The electron injection layer is formed by the following materials: Metal-organic framework materials, wherein the metal-organic framework materials have pores, and wherein the metal-organic framework materials are magnetic nano-metal-organic framework materials; Metal particles that fill the pores; The QLED device further includes: a magnetic encapsulation layer, the magnetic encapsulation layer covering the anode or the cathode, the magnetic encapsulation layer comprising: An organic matrix having pores; Magnetic particles, which fill the pores.

2. The QLED device according to claim 1, characterized in that, The metal particles are of the same type as the metal material of the cathode; and / or The particle size of the metal particles is 1 nm to 8 nm; and / or The pore size of the metal-organic framework material is 2-3 nm, and the specific surface area is 3500-4000 m². 2 / g.

3. The QLED device according to claim 1, characterized in that, The magnetic metal-organic framework nanomaterials include at least one of Ni-MOF magnetic nanomaterials, Fe-MOF magnetic nanomaterials, and Co-MOF magnetic nanomaterials; and / or The metal particles include at least one of silver particles or aluminum particles; and / or The cathode material includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg.

4. The QLED device according to claim 3, characterized in that, The metal particles constitute 3-18 wt% of the mass of the metal-organic framework material; and / or The thickness of the electron injection layer is 10 nm to 15 nm; and / or The saturation magnetization of the electron-injected layer is 25-40 emu / g.

5. The QLED device according to claim 1, characterized in that, The magnetic particles comprise a nanorod core and a magnetic shell covering the outer surface of the nanorod core. The nanorod core comprises a silver nanorod core, and the magnetic shell comprises at least one of magnetic ferrite material, magnetic nickel oxide material, and magnetic cobalt oxide material; and / or The organic matrix includes at least one of PVDF, epoxy resin, and polymethyl methacrylate; and / or The thickness of the magnetic encapsulation layer is 500nm-2500nm; and / or The saturation magnetization of the magnetic encapsulation layer is 70-80 emu / g.

6. The QLED device according to claim 1, characterized in that, Also includes: The electron transport layer is made of zinc oxide.

7. A method for fabricating a QLED device, characterized in that, Includes the following steps: The anode, quantum dot light-emitting layer, electron transport layer, electron injection layer and cathode are sequentially stacked. The electron injection layer is formed by a metal-organic framework material and metal particles. The metal-organic framework material has pores and is a magnetic nano-metal-organic framework material. The metal particles fill the pores. The method for fabricating the QLED device further includes the following step: fabricating a magnetic encapsulation layer above the cathode or the anode to form the target device; The magnetic encapsulation layer comprises: an organic matrix having pores; and magnetic particles filling the pores.

8. The method for fabricating a QLED device according to claim 7, characterized in that, Also includes: The target device is magnetized, with a magnetic field strength of 0.1T-0.5T and a magnetization duration of 0.5-4 hours. The direction of the magnetic field includes at least the plane parallel to the electron injection layer.

9. The method for fabricating a QLED device according to claim 7, characterized in that, The electron injection layer is formed through the following steps: Magnetic nanomaterials are dispersed in a first organic solvent to form a first solution; Metal ions are added to the first solution to form a second solution; The second solution was centrifuged and dried to obtain a precipitate; The precipitate was reduced to obtain a metal particle-metal-organic framework material. The metal particle-metal-organic framework material is added to a second organic solvent to form a third solution; A thin film is formed on the side of the electron transport layer away from the quantum dot light-emitting layer using a third solution and then dried to form the electron injection layer.

10. The method for fabricating a QLED device according to claim 7, characterized in that, The magnetic encapsulation layer is formed through the following steps: Metal nanomaterials and magnetic materials are added to a third organic solvent to obtain a fourth solution; The fourth solution was cooled and centrifuged to obtain a solid mixture; The solid mixture was sintered to obtain magnetic core-shell nanoparticles; The magnetic core-shell nanoparticles are dispersed into an organic matrix to form a fifth solution; The fifth solution is used to form a thin film on the side of the cathode away from the quantum dot light-emitting layer or the side of the anode away from the quantum dot light-emitting layer, and then dried to form the magnetic encapsulation layer.

11. The method for fabricating a QLED device according to claim 10, characterized in that, In the fifth solution, based on the total mass of the organic matrix, the mass percentage of the magnetic core-shell nanoparticles is 5-20 wt%.

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