Composite material and preparation method thereof, and light-emitting diode

Abstract

The present invention discloses a composite material, a preparation method thereof, and a light-emitting diode. The composite material comprises zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles. In the composite material, the benzylamine compound, after binding to the surface of the zinc oxide nanoparticles, not only passivates surface defects of the zinc oxide but also increases the distance between the zinc oxide nanoparticles, reducing surface contact and thereby reducing agglomeration. The benzylamine compound has a conjugated large π bond in the benzylamine ring, which effectively improves the carrier transport capacity of the composite material.

Description

Technical Field

[0001] The present invention relates to the field of light-emitting diodes, and in particular to a composite material, a preparation method thereof, and a light-emitting diode. Background Art

[0002] Quantum dot light-emitting diodes (QLEDs) consist of a cathode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an anode. When a voltage is applied, electrons and holes are injected from their respective electrodes, and the two combine to emit light. QLEDs are gaining increasing attention due to their superior performance, including continuously tunable spectra in the visible light region, broad absorption and narrow emission, high color purity, and high luminous intensity.

[0003] ZnO is a common II-VI semiconductor compound with a band gap of up to 3.34 eV. Its well-balanced optoelectronic properties make it an ideal electron transport layer material. ZnO-based nanocrystals, which are electron transport layer materials, have been extensively studied as carrier transport materials for QLED devices.

[0004] In the application of zinc oxide, the particle size of zinc oxide nanoparticles used to prepare electron transport layers is generally close to or even less than 5nm. In this case, the zinc oxide nanoparticles have a very large specific surface area, which makes the zinc oxide particles very unstable and prone to agglomeration. The agglomeration of zinc oxide particles has a significant impact on film formation and electron transport properties. On the other hand, zinc oxide surface defects can act as non-recombination radiation centers and have a significant quenching effect on excitons, greatly reducing the luminescence efficiency of optoelectronic devices.

[0005] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a composite material and a preparation method thereof, and a light-emitting diode, in order to solve the problem that the existing nano zinc oxide particles are prone to agglomeration.

[0007] The technical solutions of the present invention are as follows:

[0008] A composite material comprises zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles.

[0009] A method for preparing a composite material, comprising the steps of:

[0010] dispersing an alkali source in an organic solvent to obtain an alkali solution;

[0011] The alkali solution is added to a zinc salt solution, and then a benzylamine compound is added to react to prepare the composite material.

[0012] A light-emitting diode comprises an electron transport layer, wherein the electron transport layer material is the composite material described in the present invention or the composite material prepared by the preparation method described in the present invention.

[0013] Beneficial Effects: The composite material provided by the present invention includes zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles. The benzylamine compound, when bound to the surface of the zinc oxide nanoparticles, not only passivates surface defects in the zinc oxide but also increases the distance between the zinc oxide nanoparticles, reducing surface contact and thus agglomeration. The benzylamine compound's benzyl rings have conjugated large π bonds, effectively enhancing the composite material's charge carrier transport capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The present invention provides a flow chart of a preferred embodiment of a method for preparing a composite material.

[0015] Figure 2 This is a structural schematic diagram of a preferred embodiment of a quantum dot light-emitting diode with an upright structure provided by the present invention.

[0016] Figure 3 This is a structural schematic diagram of a preferred embodiment of an inverted quantum dot light-emitting diode provided by the present invention.

[0017] Figure 4 This is a UI comparison chart of the zinc oxide nanoparticles prepared in Comparative Example 1 and the composite materials prepared in Examples 1 to 3.

[0018] Figure 5 This is a comparison diagram of the zinc oxide nanoparticles prepared in Comparative Example 1 of the present invention and the composite material prepared in Example 2, which were dispersed in an organic solvent and left to stand for one month. DETAILED DESCRIPTION

[0019] The present invention provides a composite material, a preparation method thereof, and a light-emitting diode. To make the objectives, technical solutions, and effects of the present invention more clear and explicit, the present invention is further described below in detail. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0020] Due to defects on the surface of zinc oxide nanoparticles, some Zn does not combine with O to form dangling bonds, resulting in a large specific surface area and extremely high surface energy of the zinc oxide nanoparticles, which causes the zinc oxide nanoparticles to agglomerate with each other, directly leading to a decrease in the electrical conductivity of the zinc oxide nanoparticles and unbalanced carrier transmission, ultimately resulting in low device efficiency and easy quenching.

[0021] Based on this, the present invention provides a composite material comprising zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles.

[0022] In this embodiment, the amine group in the benzylamine compound is coordinated and connected with the defective zinc atoms on the surface of the zinc oxide nanoparticles. There is also a saturated methylene group between the benzyl ring and the amine group in the benzylamine compound. The methylene group can prevent the lone pair of electrons of the amine group from entering the large π bond of the benzyl ring, thereby enhancing its coordination ability with the zinc atoms on the surface of the zinc oxide nanoparticles.

[0023] In this embodiment, the benzylamine compound can passivate the surface defects of zinc oxide after being bound to the surface of the zinc oxide nanoparticles, thereby preventing the surface defects of zinc oxide from acting as non-recombinant radiation centers to quench excitons, thereby improving the luminous efficiency of the optoelectronic device.

[0024] In this embodiment, the benzylamine compound is combined with the surface of the zinc oxide nanoparticles to increase the distance between the zinc oxide nanoparticles, reduce surface contact, and thus reduce the occurrence of agglomeration.

[0025] In this embodiment, the benzyl ring in the benzylamine compound has a conjugated large π bond, which can serve as an electron transmission channel, thereby effectively improving the carrier transport capacity of the composite material.

[0026] In some embodiments, a method for preparing a composite material is also provided, such as Figure 1 As shown, it includes the steps of:

[0027] S10, dispersing the alkali source in an organic solvent to obtain an alkali solution;

[0028] S20, adding the alkali solution to the zinc salt solution, and then adding the benzylamine compound, reacting to obtain the composite material.

[0029] In this embodiment, the zinc salt solution and the alkaline solution can generate zinc oxide nanoparticles after stirring for a period of time. As the benzylamine compound is added and stirred, the amino groups in the benzylamine compound can coordinate and connect with the zinc atoms containing defects on the surface of the zinc oxide nanoparticles, thereby preparing the composite material.

[0030] In the composite material prepared in this embodiment, the benzylamine compound, after being bound to the surface of the zinc oxide nanoparticles, can not only passivate the surface defects of zinc oxide, thereby preventing the surface defects of zinc oxide from acting as non-combined radiation centers to quench excitons, thereby improving the luminous efficiency of the optoelectronic device, but also increase the distance between zinc oxide nanoparticles, reduce surface contact, and thus reduce the occurrence of agglomeration; further, the benzylamine compound has a conjugated large π bond, which can serve as an electron transmission channel, thereby effectively improving the carrier transport capacity of the composite material.

[0031] In some embodiments, the alkali solution is added to the zinc salt solution and stirred in a molar ratio of zinc ions in the zinc salt solution to hydroxide ions in the alkali solution of 1:1-2 to react and generate zinc oxide nanoparticles.

[0032] In this embodiment, the zinc salt is one or more of zinc acetate, zinc nitrate, zinc chloride, zinc sulfate and zinc acetate dihydrate, but is not limited thereto; the organic solvent is an organic alcohol, for example, the organic alcohol is one or more of isopropanol, ethanol, propanol, butanol, pentanol and hexanol, but is not limited thereto; the alkali source is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide pentahydrate, but is not limited thereto.

[0033] In some embodiments, a light-emitting diode is further provided, which includes an electron transport layer, wherein the electron transport layer material is the composite material described in the present invention or the composite material prepared by the preparation method described in the present invention.

[0034] In this embodiment, the composite material includes zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles. After the benzylamine compound is bound to the surface of the zinc oxide nanoparticles, it can not only passivate the surface defects of zinc oxide, thereby preventing the surface defects of zinc oxide from acting as non-compound radiation centers to quench excitons, thereby improving the luminous efficiency of the optoelectronic device, but it can also increase the distance between zinc oxide nanoparticles, reduce surface contact, and thus reduce the occurrence of agglomeration; further, the benzylamine compound has a conjugated large π bond, which can serve as an electron transport channel, thereby effectively improving the carrier transport capacity of the composite material. The composite material provided in this embodiment can reduce its surface defects and improve electron transport performance while reducing agglomeration, thereby enhancing the luminous efficiency and display performance of the light-emitting diode device.

[0035] In some embodiments, the light emitting diode is a QLED or an OLED. The light emitting diode structure of the present invention is described below using QLED as an example.

[0036] In some specific embodiments, a quantum dot light-emitting diode with an upright structure is provided, which includes a substrate, an anode, a hole functional layer, a quantum dot light-emitting layer, an electron transport layer and a cathode stacked in sequence from bottom to top, and the electron transport layer material is the composite material described in the present invention.

[0037] In this embodiment, the composite material can reduce surface defects and improve electron transport performance while reducing agglomeration, thereby enhancing the luminous efficiency and display performance of the quantum dot light-emitting diode device.

[0038] In some embodiments, an inverted quantum dot light-emitting diode is also provided, which includes a substrate, a cathode, an electron transport layer, a quantum dot light-emitting layer, a hole functional layer and an anode stacked in sequence from bottom to top, and the electron transport layer material is the composite material described in the present invention.

[0039] In this embodiment, the hole functional layer may be one or more of an electron blocking layer, a hole injection layer, and a hole transport layer, but is not limited thereto.

[0040] In some embodiments, the thickness of the electron transport layer is 70-90 nm.

[0041] In some embodiments, the anode material is selected from one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO) and aluminum-doped magnesium oxide (AMO), but is not limited thereto.

[0042] In some embodiments, the material of the hole transport layer is selected from organic materials with good hole transport ability, for example, 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(carbazol-9-yl)triphenylamine (TCTA), 4,4'-bis(9-carbazol)biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), doped graphene, undoped graphene and one or more of C60.

[0043] In some embodiments, the material of the quantum dot light-emitting layer is selected from one or more of red quantum dots, green quantum dots, and blue quantum dots, and may also be selected from yellow quantum dots. Specifically, the material of the quantum dot light-emitting layer is selected from one or more of CdS, CdSe, CdTe, ZnO, ZnS, ZnSe, ZnTe, GaAs, GaP, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, CuInS, CuInSe, and various core-shell structure quantum dots or alloy structure quantum dots. The quantum dots of the present invention can be selected from cadmium-containing or cadmium-free quantum dots. The quantum dot light-emitting layer of this material has the characteristics of a wide and continuously distributed excitation spectrum and a high stability of the emission spectrum.

[0044] In some specific embodiments, the thickness of the quantum dot light-emitting layer is 20-60 nm.

[0045] In some embodiments, the material of the cathode is selected from one or more of a conductive carbon material, a conductive metal oxide material and a metal material; wherein the conductive carbon material includes but is not limited to one or more of doped or undoped carbon nanotubes, doped or undoped graphene, doped or undoped graphene oxide, C60, graphite, carbon fiber and porous carbon; the conductive metal oxide material includes but is not limited to one or more of ITO, FTO, ATO and AZO; the metal material includes but is not limited to Al, Ag, Cu, Mo, Au, or alloys thereof; wherein the metal material has a morphology including but not limited to one or more of a dense film, nanowires, nanospheres, nanorods, nanocones and hollow nanospheres.

[0046] In some specific embodiments, the thickness of the cathode is 15-30 nm.

[0047] In some embodiments, a method for preparing a quantum dot light-emitting diode having an upright structure is also provided, such as Figure 2 As shown, the steps include:

[0048] S100, providing a substrate, wherein an anode is provided on the substrate;

[0049] S200, preparing a hole transport layer on the anode;

[0050] S300, preparing a quantum dot light-emitting layer on the hole transport layer;

[0051] S400, preparing an electron transport layer on the quantum dot light-emitting layer, wherein the electron transport layer material is a composite material, and the composite material includes zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles;

[0052] S500, preparing a cathode on the electron transport layer to obtain the quantum dot light emitting diode.

[0053] In this embodiment, the preparation method of each layer can be a chemical method or a physical method, wherein the chemical method includes but is not limited to one or more of chemical vapor deposition, continuous ion layer adsorption and reaction method, anodization method, electrolytic deposition method, and co-precipitation method; the physical method includes but is not limited to one or more of solution method (such as spin coating, printing method, doctor blade method, dip pulling method, immersion method, spraying method, roll coating method, casting method, slit coating method or strip coating method, etc.), evaporation method (such as thermal evaporation method, electron beam evaporation method, magnetron sputtering method or multi-arc ion plating method, etc.), deposition method (such as physical vapor deposition method, atomic layer deposition method, pulsed laser deposition method, etc.).

[0054] In some specific embodiments, the step of preparing an electron transport layer on the quantum dot light-emitting layer specifically includes: placing the substrate on which the quantum dot light-emitting layer has been prepared on a spin coater, spin-coating the composite material solution onto the substrate, and annealing at 100°C to prepare the electron transport layer.

[0055] In some specific embodiments, the step of preparing a cathode on the electron transport layer specifically includes: placing the substrate on which each functional layer has been deposited in a vapor deposition chamber and thermally evaporating a layer of 15-30 nm of metal silver or aluminum as a cathode through a mask plate, or using nano-Ag wires or Cu wires, etc. The above materials have a small resistance so that carriers can be injected smoothly.

[0056] In some embodiments, a method for preparing an inverted quantum dot light-emitting diode is also provided, such as Figure 3 As shown, it includes the steps of:

[0057] S01, providing a substrate, wherein a cathode is provided on the substrate;

[0058] S02, preparing an electron transport layer on the cathode, wherein the electron transport layer material is a composite material, and the composite material includes zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles;

[0059] S03, preparing a quantum dot light-emitting layer on the electron transport layer;

[0060] S04, preparing a hole transport layer on the quantum dot light-emitting layer;

[0061] S05. Prepare an anode on the hole transport layer to obtain the quantum dot light emitting diode.

[0062] In some embodiments, the resulting quantum dot light-emitting diodes are packaged, which can be done using a conventional machine or manually. Specifically, the packaging process is performed in an environment where both oxygen and water content are less than 0.1 ppm to ensure the stability of the QLED device.

[0063] The following is a further explanation of a composite material and its preparation method and a quantum dot light-emitting diode of the present invention through specific examples:

[0064] Comparative Example 1

[0065] 1. The preparation steps of zinc oxide nanoparticle solution are as follows:

[0066] 01. First, add an appropriate amount of zinc acetate to 50 ml of ethanol solution to make a 1 M zinc acetate ethanol solution, stir and dissolve at 70°C to prepare precursor solution 1.

[0067] 02. Weigh potassium hydroxide according to the molar ratio of Zn to OH- of 1:1.1, add sodium hydroxide to 50 ml of ethanol solution to make a 1.1 M potassium hydroxide solution, and stir to dissolve to obtain precursor solution 2.

[0068] 03. Inject precursor solution 1 into precursor solution 2 at an injection rate of 10 mL / min to clean the prepared solution and obtain an ethanol solution of zinc oxide nanoparticles.

[0069] 2. The preparation steps of a QLED device with an upright structure are as follows:

[0070] 01. Providing a substrate, on which an ITO anode is provided;

[0071] 02. Spin-coat TFB solution on the anode to prepare a hole transport layer;

[0072] 03. Spin-coat a layer of CdSe solution on the hole transport layer to produce a quantum dot light-emitting layer;

[0073] 04. Spin-coating the ethanol solution of zinc oxide nanoparticles on the quantum dot layer to prepare an electron transport layer;

[0074] 05. A layer of Ag is evaporated on the electron transport layer as a cathode to obtain the upright QLED device embodiment 1

[0075] 1. The preparation steps of the composite material are as follows:

[0076] 01. First, add an appropriate amount of zinc acetate to 50 ml of ethanol solution to make a 1 M zinc acetate ethanol solution, and stir and dissolve at 70°C to obtain precursor solution 1;

[0077] 02. Weigh potassium hydroxide at a Zn:OH molar ratio of 1:1.5, add potassium hydroxide to 50 ml of ethanol solution to make a 1.5 M potassium hydroxide solution, and stir to dissolve to obtain precursor solution 2;

[0078] 03. Inject precursor solution 1 into precursor solution 2 at an injection rate of 10 mL / min. Then use magnetic stirring. After 30 minutes, add benzylamine liquid with a molar ratio of benzylamine to Zn salt of 20:1. Heat to 50°C and stir magnetically until the solution is completely clear.

[0079] 04. Wash the prepared solution to obtain a composite material solution.

[0080] 2. The preparation steps of the upright QLED device are as follows:

[0081] 07. Providing a substrate, on which an ITO anode is provided;

[0082] 08. Spin-coat TFB solution on ITO to prepare a hole transport layer;

[0083] 09. Spin-coat a layer of CdSe solution on the hole transport layer to produce a quantum dot light-emitting layer;

[0084] 10. Spin coating the composite material solution on the quantum dot layer to prepare an electron transport layer;

[0085] 11. A layer of Ag is evaporated on the electron transport layer as a cathode to obtain the upright QLED device.

[0086] Example 2

[0087] 1. The preparation steps of the composite material are as follows:

[0088] 01 First, add an appropriate amount of zinc acetate to 50 ml of ethanol solution to prepare a 1 M zinc acetate ethanol solution, and stir and dissolve at 70°C to obtain precursor solution 1;

[0089] 02. Weigh sodium hydroxide at a Zn:OH molar ratio of 1:1.3, add sodium hydroxide to 50 ml of ethanol solution to make a 1.3 M potassium hydroxide solution, and stir to dissolve to obtain precursor solution 2;

[0090] 03. Inject precursor solution 1 into precursor solution 2 at an injection rate of 5 mL / min. Then, use magnetic stirring. After 30 minutes, add tribenzylamine powder at a molar ratio of tribenzylamine to zinc salt of 30:1. Magnetic stirring is continued at room temperature until the solution is completely clear.

[0091] 04. Wash the prepared solution to obtain a composite material solution;

[0092] 2. The preparation steps of the upright QLED device are as follows:

[0093] 07. Providing a substrate, on which an ITO anode is provided;

[0094] 08. Spin-coat a layer of TFB solution on ITO to prepare a hole transport layer;

[0095] 09. Spin-coat a layer of CdSe solution on the hole transport layer to produce a quantum dot light-emitting layer;

[0096] 10. Spin coating the composite material solution on the quantum dot layer to prepare an electron transport layer;

[0097] 11. A layer of Ag is evaporated on the electron transport layer as a cathode to obtain the upright QLED device.

[0098] Example 3

[0099] 1. The preparation steps of the composite material are as follows:

[0100] 01. First, add an appropriate amount of zinc acetate to 50 ml of ethanol solution to make a 1 M zinc acetate ethanol solution, and stir and dissolve at 70°C to obtain precursor solution 1;

[0101] 02. Weigh potassium hydroxide at a Zn:OH molar ratio of 1:1.1, add sodium hydroxide to 50 ml of ethanol solution to make a 1.1 M potassium hydroxide solution, and stir to dissolve to obtain precursor solution 2;

[0102] 03. Inject precursor solution 1 into precursor solution 2 at an injection rate of 10 mL / min. Then, use magnetic stirring. After 30 minutes, add 3-phenylbenzylamine at a molar ratio of 3-phenylbenzylamine to Zn salt of 20:1. Magnetic stirring is performed at room temperature until the solution is completely clear.

[0103] 04. Wash the prepared solution to obtain a composite material solution;

[0104] 2. The preparation steps of inverted QLED device are as follows:

[0105] 07. Providing a substrate, wherein a cathode is provided on the substrate;

[0106] 08. Spin coating the composite material solution on the cathode to prepare an electron transport layer;

[0107] 09. Spin-coat a layer of CdSe solution on the electron transport layer to produce a quantum dot light-emitting layer;

[0108] 10. Spin-coat the TFB solution on the quantum dot light-emitting layer to prepare the hole transport layer;

[0109] 11. A layer of ITO is evaporated on the hole transport layer as an anode to obtain the inverted QLED device.

[0110] The conductive properties of the composite materials prepared in Examples 1-3 and the zinc oxide nanoparticles prepared in Comparative Example 1 were tested. Figure 4 As shown, from Figure 4 It can be seen that the conductive properties of the composite materials in Examples 1-3 are significantly higher than that of the zinc oxide nanoparticles in Comparative Example 1, indicating that the combination of benzylamine compounds on the surface of zinc oxide nanoparticles can enhance their conductive properties.

[0111] The composite material prepared in Example 2 and the zinc oxide nanoparticles prepared in Comparative Example 1 were dispersed in an organic solvent and allowed to stand for one month. Figure 5 As shown. Figure 5 It can be seen that the composite material solution prepared in Example 2 is still relatively clear after standing for 1 month, indicating that the composite material has not agglomerated during the standing time; while the zinc oxide nanoparticles prepared in Comparative Example 1 become turbid after standing for one month, indicating that the zinc oxide nanoparticles have agglomerated during the standing time.

[0112] In summary, the composite material provided by the present invention includes zinc oxide nanoparticles and polypyrrole coated on the surface of the zinc oxide nanoparticles. The polypyrrole coating effectively increases the spacing between the zinc oxide nanoparticles and passivates the surface of the zinc oxide nanoparticles, reducing the generation of oxygen vacancies. The polypyrrole coating also protects the zinc oxide nanoparticles from agglomeration. The pyrrole surface contains nitrogen and carbon atoms, which effectively provide electron transport pathways and improve electron transport capacity. The polypyrrole coating also effectively isolates the zinc oxide nanoparticles from corrosion by water and oxygen. Compared with conventional ligands, the polypyrrole has a higher density.

[0113] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A light emitting diode, characterized in that: It includes an electron transport layer, wherein the electron transport layer material is a composite material; The composite material comprises zinc oxide nanoparticles and a benzylamine compound bound to the surface of the zinc oxide nanoparticles; The benzylamine compound is one or more of benzylamine, tribenzylamine, N-benzylmethylenebenzylamine, 3-phenylbenzylamine and 2-phenylbenzylamine.

2. The light emitting diode according to claim 1, characterized in that The method for preparing the composite material is characterized by comprising the steps of: dispersing an alkali source in an organic solvent to obtain an alkali solution; The alkali solution is added to a zinc salt solution, and then a benzylamine compound is added to react to prepare the composite material.

3. The light emitting diode according to claim 2, characterized in that The zinc salt solution comprises an organic solvent and a zinc salt dispersed in the organic solvent, wherein the zinc salt is one or more of zinc acetate, zinc nitrate, zinc chloride, zinc sulfate and zinc acetate dihydrate.

4. The light emitting diode according to claim 2, characterized in that The alkali source is one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide pentahydrate.

5. The light emitting diode according to claim 2, characterized in that In the step of adding the alkali solution to the zinc salt solution, the molar ratio of zinc ions in the zinc salt solution to hydroxide ions in the alkali solution is 1:1-2.

6. The light emitting diode according to claim 1, characterized in that The invention also includes an anode, a cathode, a light-emitting layer arranged between the anode and the cathode, and a hole functional layer arranged between the anode and the light-emitting layer. The electron transport layer is arranged between the cathode and the light-emitting layer.

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