Light-emitting device, preparation method thereof and display device

Abstract

The invention belongs to the technical field of display, and relates to a light-emitting device, a preparation method thereof and a display device. The light-emitting device comprises a first electrode, a light-emitting layer, an electronic function layer, a protective layer and a second electrode which are stacked. The protective layer is located between the electronic functional layer and the second electrode; wherein the material of the electronic function layer is an inorganic nano material, and the material of the protection layer comprises an N-type semiconductor metal oxide. As the protective layer is arranged between the electronic functional layer and the cathode, oxidation reaction between the electronic functional layer and the cathode can be avoided; and the protective layer comprises the N-type semiconductor metal oxide, so that the protective layer does not influence the circulation of electrons, and the electron transmission efficiency and the optical display effect of the light-emitting device are further improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a light-emitting device and a method for preparing the same, and a display device. Background Art

[0002] Electroluminescent devices include OLED (Organic Light-Emitting Diode) and QLED (Quantum Dot Light Emitting Diodes). QLED has the advantages of high color saturation, wet process preparation and high stability, which has attracted more and more attention in the research of QLED. OLED has a wide range of applications in display, lighting, smart wearable and other fields due to its good self-luminous properties, high contrast, fast response and flexible display.

[0003] An electronic functional layer is usually provided in an electroluminescent device. The electronic functional layer can be prepared by using inorganic nanomaterials. However, its electron injection efficiency still needs to be further improved to improve the luminescent performance of the light-emitting device. Summary of the invention

[0004] Based on this, the embodiments of the present application provide a light-emitting device and a method for manufacturing the same, and a display device.

[0005] In order to solve the above technical problems, the embodiment of the present application provides a light-emitting device, which adopts the following technical solution:

[0006] A light-emitting device, comprising a stacked first electrode, a light-emitting layer, an electronic functional layer, a protective layer, and a second electrode; the material of the electronic functional layer is an inorganic nanomaterial;

[0007] The protective layer is located between the electronic functional layer and the second electrode;

[0008] Wherein, the material of the protective layer includes N-type semiconductor metal oxide.

[0009] Furthermore, the thickness of the protective layer is 0.1 nm to 20 nm; and / or

[0010] The thickness of the second electrode is 10 nm to 200 nm.

[0011] Furthermore, the work function of the protective layer is 3.5 eV to 6 eV.

[0012] Further, the material of the protective layer is the N-type semiconductor metal oxide; or

[0013] The material of the protection layer includes the N-type semiconductor metal oxide and a metal material.

[0014] Further, the material of the protective layer includes a mixture of the N-type semiconductor metal oxide and the metal material; or

[0015] The protective layer includes a first protective layer close to the electronic functional layer and a second protective layer close to the second electrode. The material of the first protective layer is N-type semiconductor metal oxide, and the material of the second protective layer is metal material.

[0016] Further, the N-type semiconductor metal oxide includes at least one of ZnO, TiO2, SnO2; and / or

[0017] The metal material includes at least one of Zn, Ti and Sn.

[0018] Further, the material of the electronic functional layer includes any one or a combination of doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate, and the doped elements include any one or a combination of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; and / or

[0019] The material of the electronic functional layer is a nanocrystalline inorganic nanomaterial; and / or

[0020] The first electrode and the second electrode are each independently selected from a doped metal oxide particle electrode, a composite electrode of metal and metal oxide, a metal electrode or an alloy electrode. The material of the doped metal oxide particle electrode is selected from any one or a combination of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide. The composite electrode of metal and metal oxide is selected from 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. The material of the metal electrode is selected from any one or an alloy formed by Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg and Ba.

[0021] Accordingly, the present application also provides a method for preparing a light-emitting device, the method comprising:

[0022] Providing a light-emitting device preform, wherein the light-emitting preform comprises a first electrode, a light-emitting layer and an electronic functional layer stacked in sequence;

[0023] forming a metal film layer on the electronic functional layer;

[0024] forming a second electrode on the protective layer;

[0025] Wherein, the material of the electronic functional layer is an inorganic nanomaterial, and the material of the metal film layer includes at least one of Zn, Ti, and Sn.

[0026] Furthermore, the material of the protective layer includes N-type semiconductor metal oxide.

[0027] Furthermore, the work function of the metal film layer is 3.5 eV to 4.5 eV.

[0028] Furthermore, the step of oxidizing the metal film layer includes:

[0029] performing a heating treatment on the metal film layer;

[0030] Wherein, the heating treatment is to place the metal film layer in an oxygen-free environment for heating, and / or

[0031] The heating temperature of the heating treatment is 100° C. to 200° C., and / or the heating time of the heating treatment is 1 min to 15 min.

[0032] Further, the material of the protective layer is the N-type semiconductor metal oxide; or

[0033] The material of the protective layer includes the N-type semiconductor metal oxide and a metal material; and / or

[0034] The N-type semiconductor metal oxide includes at least one of ZnO, TiO2, SnO2; and / or

[0035] The metal material includes at least one of Zn, Ti and Sn.

[0036] Furthermore, the light emitting device preform further comprises a hole functional layer disposed between the first electrode and the light emitting layer;

[0037] The material of the hole functional layer includes any one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, T·APC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal tin compounds, doped graphene, undoped graphene and C60 or a combination thereof; and / or

[0038] The material of the light-emitting layer includes any one or a combination of single-structure quantum dots and core-shell structure quantum dots. The material of the single-structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots are selected from any one or a combination 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 CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnS One or more of CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound includes SnS, SnSe, SnTe, PbS, PbSe, Pb Te, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, the III-V group compound includes GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlP One or more of As, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound includes one or more of CuInS2, CuInSe2 and AgInS2; and / or

[0039] The material of the electronic functional layer includes any one or a combination of doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate, and the doped elements include any one or a combination of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium.

[0040] Correspondingly, the present application also provides a display device, which includes the light-emitting device as described above or a light-emitting device prepared by the method for preparing the light-emitting device as described above.

[0041] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0042] By adding a protective layer between the electronic functional layer and the electrode, oxidation reaction between the inorganic nanomaterials of the electronic functional layer and the electrode can be avoided. Because the components of the protective layer include N-type semiconductor metal oxides, the electron injection of the light-emitting device is effectively improved, thereby improving the electron transmission efficiency and optical display effect of the light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the solutions in the present application or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 is a structural diagram of a light-emitting device according to an embodiment of the present application;

[0045] Figure 2 It is a flow chart of a method for preparing a light-emitting device according to an embodiment of the present application.

[0046] Reference numerals:

[0047] The light emitting device 10 , the substrate 100 , the anode 200 , the hole functional layer 300 , the light emitting layer 400 , the electron functional layer 500 , the protective layer 600 , and the cathode 700 . DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0049] In this application, unless otherwise stated, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels and do not impose numerical requirements or establish an order.

[0050] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0051] In the present application, "at least one" means one or more, and "plurality" means two or more. "One or more", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: 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.

[0052] Various embodiments of the present application may be presented 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 understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0053] Optical display effect refers to the visual effect presented by the display device when it displays images, text, graphics and other contents to the observer. This effect involves a variety of visual characteristics, such as brightness, contrast, color saturation, color accuracy, resolution, clarity, viewing angle stability, etc. In a display device, as the pixel size decreases, the light-color crosstalk between pixel units will become more and more serious, that is, when a certain pixel unit emits light, the carriers of the pixel unit will diffuse laterally to the non-pixel unit area, that is, the gap between adjacent electrodes, and even diffuse to adjacent pixel units, thereby causing light-color crosstalk, affecting color accuracy and color saturation.

[0054] In actual work, the inventors conducted XPS (full name: X-ray Photoelectron Spectroscopy) tests on QLED devices and found that the half-peak width of the Ag3d peak at the interface between the electronic functional layer and the electrode (ZnMgO / Ag) was larger than the half-peak width of single substance Ag (about 1eV), indicating that the Ag at the ZnMgO / Ag interface was in an oxidized state. The atomic concentration of the silver element first increased and then decreased, while the atomic concentrations of oxygen, zinc, and carbon also increased and then decreased with the etching cycle, and when the atomic concentration increased, the atomic concentration of the silver element decreased. That is, the surface cathode is oxidized, thereby causing the Ag concentration to decrease and elements such as oxygen to increase, that is, when the electron transport layer includes inorganic nanomaterials, such as zinc oxide, the free oxygen in the electron transport layer or the oxygen in the external connection will cause the electron transport layer and the cathode to undergo an oxidation reaction, and the oxidation reaction will affect the luminous efficiency of the light-emitting device.

[0055] To solve the above problems, please refer to Figure 1 . Take the first electrode as the anode 200 and the second electrode as the cathode 700 as an example. The embodiment of the present application provides a light-emitting device 10, which includes a stacked electronic functional layer 500, a protective layer 600 and a cathode 700, and the material of the electronic functional layer 500 is an inorganic nanomaterial. The protective layer 600 is located between the electronic functional layer 500 and the cathode 700, and is used to prevent the cathode 700 from contacting the electronic functional layer 500. Among them, the components of the protective layer 600 include N-type semiconductor metal oxide. At this time, the protective layer 600 prevents the cathode 700 and the electronic functional layer 500 from directly contacting each other, thereby avoiding oxidation reactions between the electronic functional layer 500 and the cathode 700. Because the components of the protective layer 600 include N-type semiconductor metal oxide, the N-type semiconductor metal oxide has excellent electrical conductivity and good light transmittance, so the protective layer 600 will not affect the injection and transmission of electrons, thereby improving the electron transmission efficiency and optical display effect of the light-emitting device 10.

[0056] Further, the thickness of the protective layer is 0.1nm to 20nm; and / or the thickness of the second electrode is 10nm to 200nm. Taking the second electrode as a cathode as an example, in the actual use of the light-emitting device, the thickness of the protective layer 600 will affect its effect of blocking the cathode 700 and the electronic functional layer 500. Therefore, when the thickness of the protective layer 600 is 0.1nm to 20nm, the protective layer 600 can not only achieve the effect of blocking the cathode 700 and the electronic functional layer 500 from contacting, but also avoid the light-emitting device 10 from having a long response time, and can also reduce the energy consumption and heat of the light-emitting device 10 to increase the life of the light-emitting device 10. Preferably, when the thickness of the protective layer 600 is between 1nm and 10nm, the above-mentioned performance and effect of the light-emitting device 10 are better. The thickness of the cathode 700 will also affect the response time, energy consumption, and life of the light-emitting device 10. Therefore, when its thickness is between 10nm and 200nm, it can reduce the response time and energy consumption of the light-emitting device 10 and increase the life of the light-emitting device 10.

[0057] It is understood that the thickness of the protective layer 60 can be any one of 0.1nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, or a range formed between any two values. The thickness of the second electrode can be any one of 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm, 160nm, 170nm, 180nm, 190nm, or 200nm, or a range formed between any two values.

[0058] Furthermore, the work function of the protective layer 600 is 3.5eV to 6eV. At this time, the work function of the protective layer 600 is close to the work function of the electronic functional layer 500, which can reduce the scattering and loss of electrons at the interface, and can also avoid increasing the energy barrier due to the work function being too large or too small, restricting the effective injection and transmission of electrons, thereby achieving the effect of improving the performance and stability of the light-emitting device 10. It can be understood that the work function of the protective layer 600 can be any one of 3.5eV, 3.6eV, 3.7eV, 3.8eV, 3.9eV, 4.0eV, 4.1eV, 4.2eV, 4.3eV, 4.4eV, 4.5eV, 4.6eV, 4.7eV, 4.8eV, 4.9eV, 5.0eV, 5.1eV, 5.2eV, 5.3eV, 5.4eV, 5.5eV, 5.6eV, 5.7eV, 5.8eV, 5.9eV, and 6.0eV, or a range formed between any two of the values.

[0059] It can be understood that the structure of the light emitting device 10 may include a substrate 100, on which an anode 200, a hole functional layer 300, a light emitting layer 400, an electron functional layer 500, a protective layer 600, and a cathode 700 are sequentially stacked. The hole functional layer 300 includes a hole injection layer and / or a hole transport layer, and the electron functional layer 500 includes an electron injection layer and / or an electron transport layer. When the electronic functional layer includes an electron injection layer and an electron transport layer, the protective layer 600 may be disposed on the electron injection layer and / or the electron transport layer.

[0060] Further, the material of the protective layer 600 is an N-type semiconductor metal oxide; or the material of the protective layer 600 includes an N-type semiconductor metal oxide and a metal material. Since the degree of oxidation reaction between the protective layer 600 and the electronic functional layer 500 is affected by multiple factors such as oxygen content, free oxygen content, reaction time, temperature, etc., when the metal material on the protective layer 600 is completely oxidized, the material of the protective layer 600 is an N-type semiconductor metal oxide. When the metal material on the protective layer 600 is only partially oxidized, the material of the protective layer 600 includes an N-type semiconductor metal oxide and a metal material.

[0061] Further, the material of the protective layer 600 includes a mixture of N-type semiconductor metal oxide and metal material; or the protective layer 600 includes a first protective layer close to the electronic functional layer 500 and a second protective layer close to the second electrode, the material of the first protective layer is N-type semiconductor metal oxide, and the material of the second protective layer is metal material. When the light-emitting device has multiple protective layers 600, each protective layer 600 can be stacked together, or located on the surface of the electron transport layer and the electron injection layer respectively. N-type semiconductor metal oxide includes at least one of ZnO, TiO2, and SnO2; and / or the metal material includes at least one of Zn, Ti, and Sn. The metal material in this embodiment has good electrical conductivity, and it matches the energy band structure between the electron transport layer, which can improve the performance of the light-emitting device 10. At the same time, the process performance of the above-mentioned materials is suitable for common processes such as solution method and evaporation, which can improve the production efficiency of the light-emitting device.

[0062] Further, the material of the electronic functional layer includes any one or a combination of doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, barium titanate, and the doped elements include any one or a combination of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; and / or

[0063] The material of the electronic functional layer is a nanocrystalline inorganic nanomaterial; and / or

[0064] The first electrode and the second electrode are each independently selected from a doped metal oxide particle electrode, a composite electrode of metal and metal oxide, a metal electrode or an alloy electrode. The material of the doped metal oxide particle electrode is selected from any one or a combination of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide. The composite electrode of metal and metal oxide is selected from 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. The material of the metal electrode is selected from any one or an alloy formed by Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg and Ba.

[0065] It is understandable that when the material of the electronic functional layer is a nanocrystalline material, the nanocrystalline material has a large specific surface area and a short electron transmission distance, which can improve the electron transmission efficiency, but there are abundant defects and active sites on its surface, which are easy to react with the metal material of the cathode to produce insulating oxides, which may cause the electron transmission efficiency to become lower. However, in the embodiment of the present application, there is a protective layer between the cathode and the electron transmission layer, and the protective layer can isolate the contact between the cathode and the electron transmission layer, so when a nanocrystalline electron transmission layer material is used as the electron transmission layer, the electron transmission efficiency can be further improved.

[0066] When the material of the protective layer is the same as that of the electronic functional layer, the electronic functional layer and the protective layer can be regarded as the same layer. It should be understood that because the preparation of the protective layer is by metal oxidation, the protective layer will consume the free oxygen in the electronic functional layer during the formation process. At this time, after the second electrode is deposited on the protective layer, the free oxygen content in the protective layer and the electronic functional layer is relatively small, so it can still prevent the second electrode from being oxidized to a certain extent. When the second electrode is Au, Ag, Al, Cu or their alloys, these materials have good electrical conductivity, but surface defects and activity, and the second electrode has good electrical conductivity, thereby effectively reducing the driving voltage of the light-emitting device.

[0067] Accordingly, an embodiment of the present application further provides a method for preparing a light-emitting device, the method comprising:

[0068] S100, providing a light-emitting device preform, wherein the light-emitting preform includes a first electrode, a light-emitting layer, and an electronic functional layer stacked in sequence;

[0069] S200, forming a metal film layer on the electronic functional layer;

[0070] S300, performing oxidation treatment on the metal film layer to form a protective layer;

[0071] S400, forming a second electrode on the protective layer.

[0072] The material of the electronic functional layer is an inorganic nanomaterial, and the material of the metal film layer includes at least one of Zn, Ti, and Sn. When a metal film layer is formed on the electronic functional layer by the method in this embodiment, the metal film layer will directly contact the electronic functional layer, replace the second electrode to undergo oxidation reaction with the electronic functional layer, consume free oxygen on the surface of the electronic functional layer, and because the second electrode is formed on the protective layer and does not directly contact the electronic functional layer, the electronic functional layer and the second electrode will not react, so it can improve the electronic transmission efficiency and optical display effect of the light-emitting device.

[0073] It is understandable that the structure of the light-emitting device preform may include a substrate and a first electrode, a hole functional layer, and a light-emitting layer stacked in sequence on the substrate, and the electron transport layer is arranged on the light-emitting layer. The second electrode includes a cathode, and the first electrode includes an anode. The method of forming a protective layer on the electronic functional layer includes but is not limited to any method or a combination thereof such as vacuum evaporation and vapor deposition. The method of forming a cathode on the protective layer includes but is not limited to evaporation, deposition and other methods. The metal film layer can be a single metal or an alloy. The method of forming a hole functional layer and an electron transport layer includes but is not limited to a solution method and self-assembly, and the method of forming an anode or a cathode includes but is not limited to evaporation, deposition, and a solution method. The method of forming a light-emitting layer includes but is not limited to a solution method and deposition. Among them, the solution method includes spin coating, printing, inkjet printing, blade coating, dip pulling, immersion, spraying, roll coating, casting, slit coating, strip coating, and full-surface coating.

[0074] Furthermore, the material of the protective layer includes N-type semiconductor metal oxide. At this time, because N-type semiconductor metal oxide has excellent conductivity and good light transmittance, compared with non-N-type semiconductor metal oxide, the protective layer in this embodiment itself will not affect the flow of electrons, that is, it can further improve the electron transmission efficiency of the light-emitting device.

[0075] Furthermore, the work function of the metal film layer is 3.5 eV to 4.5 eV.; and / or the material of the metal film layer includes at least one of Zn, Ti, and Sn. In this case, the work function of the metal film layer is close to the work function of the cathode, which can reduce the scattering and loss of electrons at the interface, and can also avoid the energy barrier being increased due to the work function being too large or too small, which restricts the effective injection and transmission of electrons, thereby achieving the effect of improving the performance and stability of the light-emitting device.

[0076] Furthermore, the step of oxidizing the metal film layer includes:

[0077] The metal film layer is subjected to a heat treatment; wherein the heat treatment is to heat the metal film layer in an oxygen-free environment; and / or the heating temperature of the heat treatment is 100° C. to 200° C.; and / or the heating time of the heat treatment is 1 min to 15 min.

[0078] At this time, the metal film layer is heated in an oxygen-free environment, which can prevent the oxygen in the air from reacting with the metal film layer, so that the free oxygen in the inorganic nanomaterial can be fully consumed, and the cathode and free oxygen combination reaction can be further avoided. At the same time, the heating time and heating temperature in this application are suitable, which can ensure that the metal film layer fully consumes the free oxygen on the electron transport layer, and can prevent the metal film layer or the electron transport layer from being degraded due to excessive temperature and long heating time, and finally improve the stability, lifespan, and optical display effect of the prepared light-emitting device. It is understandable that the oxygen-free environment includes but is not limited to a nitrogen environment or a vacuum environment. The heating temperature can be any one of 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C, or a range formed between any two values. The heating time can be any one of 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min, and 15 min, or a range formed between any two values.

[0079] Furthermore, the light emitting device preform further includes a hole functional layer disposed between the first electrode and the light emitting layer;

[0080] The material of the hole functional layer includes any one or a combination of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, T·APC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal tin compounds, doped graphene, undoped graphene and C60; and / or

[0081] The material of the light-emitting layer includes any one or a combination of single structure quantum dots and core-shell structure quantum dots. The material of the single structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots are selected from any one or a combination 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 CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSe Te, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, IV-VI compounds include SnS, SnSe, SnTe, PbS, PbSe, Pb Te, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, III-V compounds include GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, Al One or more of PAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compounds include one or more of CuInS2, CuInSe2 and AgInS2.

[0082] Accordingly, the embodiment of the present application further provides a display device, the display device comprising the above-mentioned light-emitting device. A protective layer is provided between the electronic functional layer and the cathode in the display device, so that the electron transmission efficiency and the optical display effect are improved.

[0083] It is understandable that the display device can be any electronic product with a display function, including but not limited to smart phones, tablet computers, laptops, digital cameras, digital video cameras, smart wearable devices, smart weighing electronic scales, car displays, televisions or e-book readers, among which smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.

[0084] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.

[0085] Example 1

[0086] This embodiment provides a method for preparing a light emitting device, and the preparation method is as follows:

[0087] Step 1, providing a prefabricated part, wherein the prefabricated part is provided with an electronic functional layer, and the material of the electronic functional layer is zinc oxide.

[0088] Step 2, forming a protective layer: The preform is transferred to a vacuum evaporation chamber for deposition to form a zinc metal film layer on the electronic functional layer.

[0089] Step 3, forming a protective layer. The metal film layer is transferred to a vacuum chamber and subjected to a heat treatment, wherein the heating temperature of the heat treatment is 150° C. and the heating time of the heat treatment is 10 min, to form a protective layer, the protective layer comprising a mixture of zinc oxide and zinc, and the thickness of the protective layer is 10 nm.

[0090] Step 4: transfer the protective layer to a vacuum evaporation chamber, and deposit a layer of aluminum metal cathode on the protective layer, wherein the thickness of the cathode is 150 nm.

[0091] Step 5, packaging.

[0092] Example 2

[0093] This embodiment is basically the same as the embodiment 1, except that the material of the metal film formed in step 2 is tin, and the material of the protective layer formed in step 3 is tin oxide.

[0094] Example 3

[0095] This embodiment is basically the same as the embodiment 1, except that the material of the metal film formed in step 2 is titanium, and the material of the protective layer formed in step 3 is titanium oxide.

[0096] Comparative Example 1

[0097] The comparative example is substantially the same as Example 1, except that step 2 and step 3 are omitted, and in step 4, a cathode is deposited directly on the electronic functional layer.

[0098] Comparative Example 2

[0099] This embodiment is basically the same as Embodiment 1, except that the metal deposited on the electronic functional layer in Step 2 is silver metal.

[0100] Comparative Example 3

[0101] This embodiment is substantially the same as embodiment 1, except that step 2 and step 3 are omitted, and the cathode material deposited in step 4 is zinc.

[0102] The voltage and efficiency of the light-emitting device were measured using a JV test device, and the device life was tested using a service life test device. The initial brightness was fixed at 1000 nits for brightness decay test, and the device life of comparative example 1 was used as a reference index, and the luminous efficiency of comparative example 1 was used as a reference index. Table 1 was obtained.

[0103] Table 1:

[0104] project Voltage (V) Efficiency (cd / A) Lifespan (h) Example 1 4.8 105％ 120％ Example 2 4.9 105％ 115％ Example 3 4.8 105％ 110％ Comparative Example 1 5.0 100％ 100％ Comparative Example 2 5.2 95％ 85％ Comparative Example 3 6.0 100％ 110％

[0105] Please refer to Table 1, and take the lifespan and efficiency of the comparative example as the reference lifespan and reference voltage. By comparing Examples 1 to 3 and Comparative Example 1, it can be seen that by adding a protective layer, the lifespan and luminous efficiency of the light-emitting device are improved, and the driving voltage is also reduced.

[0106] By comparing Examples 1 to 3 and Comparative Example 2, it can be seen that if the protective layer is a non-N-type semiconductor metal oxide, the luminous efficiency and the life of the light-emitting device will both decrease, and the driving voltage will also increase to a certain extent.

[0107] By comparing Examples 1 to 3 and Comparative Example 3, it can be seen that if the cathode is completely composed of zinc or the like, although the life of the light-emitting device can be improved, the driving voltage increases significantly, thereby causing the light-emitting device to have risks of electric shock, increased energy consumption, unstable performance, and other hidden dangers.

[0108] By comparing Examples 1 to 3, it can be seen that the protective layers formed by different N-type semiconductor metal oxides can improve the lifespan and luminous efficiency of the light-emitting device and reduce the driving voltage to varying degrees.

[0109] In summary, the light-emitting device prepared by the method for preparing the light-emitting device provided in the present application has the advantages of long life, high luminous efficiency and low driving voltage.

[0110] The light-emitting device and its preparation method, and the display device provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0111] Obviously, the embodiments described above are only some embodiments of the present application, rather than all embodiments. The preferred embodiments of the present application are given in the accompanying drawings, but they do not limit the patent scope of the present application. The present application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the aforementioned embodiments, for those skilled in the art, it is still possible to modify the technical solutions recorded in the aforementioned specific implementation methods, or to perform equivalent replacement of some of the technical features therein. Any equivalent structure made using the contents of the specification and drawings of this application, directly or indirectly used in other related technical fields, is similarly within the scope of patent protection of this application.

[0112] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, combinations, substitutions and variations may be made to the embodiments without departing from the principles and intent of the present application, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A light emitting device, characterized in that: The light emitting device comprises a stacked first electrode, a light emitting layer, an electronic functional layer, a protective layer and a second electrode; The protective layer is located between the electronic functional layer and the second electrode; Wherein, the material of the electronic functional layer is an inorganic nanomaterial, and the material of the protective layer includes an N-type semiconductor metal oxide.

2. The light emitting device according to claim 1, characterized in that: The thickness of the protective layer is 0.1 nm to 20 nm; and / or The thickness of the second electrode is 10 nm to 200 nm.

3. The light emitting device according to claim 1, characterized in that: The work function of the protective layer is 3.5 eV to 6 eV.

4. The light emitting device according to claim 1, characterized in that: The material of the protective layer is the N-type semiconductor metal oxide; or The material of the protection layer includes the N-type semiconductor metal oxide and a metal material.

5. The light emitting device according to claim 4, characterized in that: The material of the protective layer includes a mixture of the N-type semiconductor metal oxide and the metal material; or The protective layer includes a first protective layer close to the electronic functional layer and a second protective layer close to the second electrode. The material of the first protective layer is N-type semiconductor metal oxide, and the material of the second protective layer is metal material.

6. The light emitting device according to claim 4, characterized in that: The N-type semiconductor metal oxide includes at least one of ZnO, TiO2, SnO2; and / or The metal material includes at least one of Zn, Ti and Sn.

7. The light emitting device according to claim 1, characterized in that: The material of the electronic functional layer includes any one or a combination of doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, barium titanate, and the doped elements include any one or a combination of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium; and / or The material of the electronic functional layer is a nanocrystalline inorganic nanomaterial; and / or The first electrode and the second electrode are each independently selected from a doped metal oxide particle electrode, a composite electrode of metal and metal oxide, a metal electrode or an alloy electrode. The material of the doped metal oxide particle electrode is selected from any one or a combination of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide and aluminum-doped magnesium oxide. The composite electrode of metal and metal oxide is selected from 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. The material of the metal electrode is selected from any one or an alloy formed by Ag, Al, Cu, Mo, Au, Pt, Si, Ca, Mg and Ba.

8. A method for preparing a light emitting device, characterized in that: The method comprises: Providing a light-emitting device preform, wherein the light-emitting preform comprises a first electrode, a light-emitting layer and an electronic functional layer stacked in sequence; forming a metal film layer on the electronic functional layer; performing oxidation treatment on the metal film layer to form a protective layer; forming a second electrode on the protective layer; Wherein, the material of the electronic functional layer is an inorganic nanomaterial, and the material of the metal film layer includes at least one of Zn, Ti, and Sn.

9. The method for preparing a light emitting device according to claim 8, characterized in that: The material of the protection layer includes N-type semiconductor metal oxide.

10. The method for preparing a light emitting device according to claim 9, characterized in that: The work function of the metal film layer is 3.5 eV to 4.5 eV.

11. The method for preparing a light emitting device according to claim 9, characterized in that: The step of oxidizing the metal film layer comprises: performing a heating treatment on the metal film layer; Wherein, the heating treatment is to place the metal film layer in an oxygen-free environment for heating, and / or The heating temperature of the heating treatment is 100° C. to 200° C., and / or the heating time of the heating treatment is 1 min to 15 min.

12. The method for preparing a light emitting device according to claim 9, characterized in that: The material of the protective layer is the N-type semiconductor metal oxide; or The material of the protective layer includes the N-type semiconductor metal oxide and a metal material; and / or The N-type semiconductor metal oxide includes at least one of ZnO, TiO2, SnO2; and / or The metal material includes at least one of Zn, Ti and Sn.

13. The method for preparing a light emitting device according to claim 8, characterized in that: The light emitting device preform further comprises a hole functional layer disposed between the first electrode and the light emitting layer; The material of the hole functional layer includes any one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, T·APC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal tin compounds, doped graphene, undoped graphene and C60 or a combination thereof; and / or The material of the light-emitting layer includes any one or a combination of single-structure quantum dots and core-shell structure quantum dots. The material of the single-structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots are selected from any one or a combination 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 CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnS One or more of CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe, and the IV-VI group compound includes SnS, SnSe, SnTe, PbS, PbSe, Pb Te, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, the III-V group compound includes GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlP One or more of As, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb, and the I-III-VI group compound includes one or more of CuInS2, CuInSe2 and AgInS2; and / or The material of the electronic functional layer includes any one or a combination of doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, lithium zinc oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate, and the doped elements include any one or a combination of aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium.

14. A display device, characterized in that: The display device comprises the light-emitting device according to any one of claims 1 to 7 or a light-emitting device prepared by the method for preparing a light-emitting device according to any one of claims 8 to 13.

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