Quantum dot light emitting diode based on anode modification and preparation method and application thereof

Abstract

The invention discloses a quantum dot light-emitting diode based on anode modification and a preparation method and application thereof, and belongs to the technical field of photovoltaic devices. The quantum dot light-emitting diode comprises an anode, a cathode, and a hole injection layer, a hole transport layer, a quantum dot light-emitting layer and an electron transport layer which are sequentially arranged between the anode and the cathode. And the raw material of the hole injection layer is PEDOT: PSS doped self-assembled molecules. According to the invention, PEDOT: PSS is combined with self-assembled molecules, so that the corrosivity of PEDOT: PSS is effectively reduced, and the interface stability is enhanced; the combination of the self-assembled molecules and the anode material can effectively reduce the hole injection barrier and improve the hole injection efficiency, the brightness, efficiency and device stability of the QLED device modified based on the PEDOT: PSS and the self-assembled molecule anode are remarkably improved, and the external quantum efficiency of the dark blue light quantum dot light emitting diode can be improved to 18.33%.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic devices, and particularly relates to a quantum dot light-emitting diode based on anode modification, and a preparation method and application thereof. Background Art

[0002] With the continuous development of technology, people's technical requirements for the display field are getting higher and higher. As a new display technology, quantum dot light-emitting diodes (QLEDs) are regarded as one of the important directions in the future display field due to their advantages such as high color gamut, high brightness, long lifespan, and low power consumption. A QLED device is usually a multi-layer device structure containing a transparent anode (ITO), a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), an electron injection layer (EIL), and a metal cathode. The interfaces between the respective functional layers directly affect the injection and transport of charge carriers, the exciton recombination region, and the exciton recombination efficiency, and are also important factors determining the device performance. Among them, improving the interface between the anode and the organic functional layer is the main way to optimize the performance of QLED devices. Modifying the ITO anode is used to achieve purposes such as improving energy level matching and enhancing interface stability, laying a foundation for the preparation of high-performance QLED devices.

[0003] In order to improve the interfacial properties between the anode and the organic functional layer, there are currently two main modification methods: one is to directly treat the ITO surface using physical or chemical methods such as plasma treatment, acid-base adsorption treatment, and self-assembled monolayer modification, and the other is to indirectly change the properties of the anode by introducing a buffer layer at the interface between the anode and the organic functional layer. Common plasma treatment methods include oxygen plasma treatment, fluorocarbon plasma treatment, and ultraviolet ozone treatment, etc. These methods can remove residual pollutants on the ITO surface, make the substrate surface smoother, thereby increasing the surface free energy and wettability; acid-base adsorption treatment refers to treating the ITO with chemical solutions such as ethanol, sodium hydroxide, phosphoric acid, and tetrabutylammonium hydroxide to adjust the surface properties, and the results are closely related to the treatment methods; molecular self-assembly is through chemical reactions or electrostatic interactions, and the active head groups of organic molecules spontaneously form a closely packed thin film structure on the anode ITO surface, thereby improving the surface morphology of the anode ITO; introducing a buffer layer is to insert organic substances with a moderate HOMO energy level (such as PEDOT:PSS, copper phthalocyanine, and polyaniline, etc.) and transition metal oxides (such as MoO3, WO3, V2O5, and NiO x etc.) to achieve the purpose of changing the properties of the anode.

[0004] As a physical modification method, the modification effect of plasma treatment has a certain timeliness, and it will cause the ITO surface to be highly hydrophilic, reducing the wetting performance of the organic functional layer, etc. Although acid-base adsorption treatment can improve the interface properties, it is easy to corrode materials, the process is complex, and the environmental protection cost is high. Introducing a buffer layer to modify the interface between the anode and the organic functional layer, among which poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is the most widely used hole injection material, but its strong acidity and hygroscopicity will corrode the electrode and the adjacent functional layer, seriously affecting the service life of the device. Self-assembled monolayers (SAMs) modification has the characteristics of simple operation, adjustable molecules, and environmental friendliness, which is an ideal way to improve the properties of ITO. However, the self-assembled monolayers are relatively thin, which makes the improvement of the performance of the modified QLED device slightly insufficient. Summary of the Invention

[0005] To solve the above problems in the prior art, the present invention provides a quantum dot light-emitting diode based on anode modification, its preparation method and application.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a quantum dot light-emitting diode based on anode modification, including an anode, a cathode, and a hole injection layer (HIL), a hole transport layer (HTL), a quantum dot emission layer (EML), and an electron transport layer (ETL) sequentially arranged between the anode and the cathode; the raw material of the hole injection layer is PEDOT:PSS doped with self-assembled molecules.

[0008] As a preferred solution of the present invention, the HOMO energy level of the PEDOT:PSS is -5.2 eV, and the self-assembled molecules include one or more of phosphonic acid-based self-assembled molecules, carboxylic acid-based self-assembled molecules, and silane-based self-assembled molecules.

[0009] As a preferred embodiment of the present invention, the phosphonic acid-based self-assembled molecules include (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz), [2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl]phosphonic acid (Me-2PACz), [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid (MeO-2PACz), [2-(3,6-difluoro-9H-carbazol-9-yl)ethyl]phosphonic acid (F-2PACz), [2-(3,6-dichloro-9H-carbazol-9-yl)ethyl]phosphonic acid (Cl-2PACz), [2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid (Br-2PACz), (4-(9H-carbazol-9-yl)ethyl)phosphonic acid (4PACz), [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz), [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid (MeO-4PACz), [4-(7H-dibenzo[c,g]carbazol-7-yl)butyl]phosphonic acid (Cb2Naph), phenylphosphonic acid (PPA), 3,4,5-trifluorobenzylphosphonic acid (mpF3BnPA), 2,3,4,5,6-pentafluorobenzylphosphonic acid (F5BnPA), 4-trifluoromethylbenzylphosphonic acid (pCF3BnPA), 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecylphosphonic acid (HF 17 DPA), and one or more of 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorododecylphosphonic acid (HF 21 DPA); the carboxylic acid-based self-assembled molecules include benzoic acid (BA), 4-biphenylcarboxylic acid (BCA), 4-trifluoromethyl-benzoic acid (3FBA), 4'-trifluoromethyl-biphenyl-4-carboxylic acid (3FBCA), anthracene carboxylic acid (NA), fluorene-4-carboxylic acid (FCA), and 9-H-carbazole-2-carboxylic acid (CzCA), one or more of which; the silane-based self-assembled molecules include 3-trifluoropropyltrimethoxysilane (TFPMS), perfluorooctyltriethoxysilane (HF 13 DES), and one or more of perfluorodecyltriethoxysilane (HF 17 DES).

[0010] The present invention also provides a method for preparing a quantum dot light-emitting diode based on anode modification as described above, comprising the following steps:

[0011] (1) Cleaning and pre-treating the anode material with a substrate;

[0012] (2) Preparation of hole injection layer: Dissolve the self-assembled molecules in ethanol to obtain a self-assembled molecule ethanol solution, then mix it with PEDOT:PSS to obtain a mixed solution, and then spin-coat it on the anodic material pretreated in step (1), anneal and cool to obtain a hole injection layer film;

[0013] (3) Preparation of hole transport layer: Prepare a chlorobenzene solution of poly(N-vinylcarbazole) or a chlorobenzene solution of poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)], spin-coat it on the hole injection layer film obtained in step (2), anneal and cool to obtain a hole transport layer film;

[0014] (4) Preparation of quantum dot light-emitting layer: Take a ZnCdS / ZnS quantum dot n-octane solution or a CdSe / ZnS quantum dot n-octane solution, spin-coat it on the hole transport layer film obtained in step (3), anneal and cool to obtain a quantum dot light-emitting layer film;

[0015] (5) Preparation of electron transport layer: Take a ZnMgO ethanol solution or a ZnO ethanol solution, spin-coat it on the quantum dot light-emitting layer film obtained in step (4), anneal and cool to obtain an electron transport layer film;

[0016] (6) Preparation of cathode: Prepare a metal electrode on the electron transport layer film obtained in step (5) by vacuum evaporation.

[0017] As a preferred embodiment of the present invention, the anodic material in step (1) is ITO; plasma pretreatment is adopted; in step (2), the concentration of the self-assembled molecule ethanol solution is 1-3 mmol / L, the volume ratio of PEDOT:PSS to the self-assembled molecule ethanol solution in the hole injection layer is 1:1, the annealing temperature is 120-140 °C, the time is 15-30 min, and the thickness of the hole injection layer film is 20-40 nm; in step (3), the concentrations of the chlorobenzene solution of poly(N-vinylcarbazole) and the chlorobenzene solution of poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] are both 6-12 mg / mL, the annealing temperature is 130-140 °C, the time is 15-30 min, and the thickness of the hole transport layer film is 20-40 nm.

[0018] As a preferred embodiment of the present invention, in step (4), the concentrations of the ZnCdS / ZnS quantum dot n-octane solution and the CdSe / ZnS quantum dot n-octane solution are both 12-18 mg / mL, the annealing temperature is 80-100 °C, the time is 3-6 min, and the thickness of the quantum dot light-emitting layer thin film is 20-30 nm; in step (5), the concentrations of the ZnMgO ethanol solution and the ZnO ethanol solution are both 15-20 mg / mL, the annealing temperature is 80-100 °C, the time is 15-30 min, and the thickness of the electron transport layer thin film is 30-40 nm; in step (6), the metal electrode includes a metal aluminum electrode with a thickness of 80-100 nm.

[0019] The present invention also provides an application of the quantum dot light-emitting diode based on the anodic modification as described above in the display field.

[0020] As a preferred embodiment of the present invention, it specifically includes applications in mobile phones, laptop computers, tablet computers, smart watches, smart TVs, and VR technologies.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention creates a new method for modifying the anode, combining PEDOT:PSS with self-assembled molecules. On the one hand, it effectively reduces the corrosion of PEDOT:PSS and enhances the interface stability. On the other hand, the self-assembled molecules combine with the anode material, making the energy levels more matched, effectively reducing the hole injection barrier, and improving the hole injection efficiency. The QLED device modified by the PEDOT:PSS and self-assembled molecule anode has a very significant improvement in terms of brightness, efficiency, and device stability, and can increase the external quantum efficiency of the deep blue quantum dot light-emitting diode to 18.33%.

[0023] (2) The present invention retains the original device structure without adding additional functional layers, and the device preparation cost is relatively low. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 The electroluminescence performance of the quantum dot light-emitting diode device prepared in Example 1;

[0026] Figure 2Curves of luminance - voltage - current density for the quantum dot light - emitting diode devices prepared in Example 1, Comparative Example 1, and Comparative Example 2;

[0027] Figure 3 Curves of current efficiency - luminance for the quantum dot light - emitting diode devices prepared in Example 1, Comparative Example 1, and Comparative Example 2;

[0028] Figure 4 Curves of external quantum efficiency - luminance for the quantum dot light - emitting diode devices prepared in Example 1, Comparative Example 1, and Comparative Example 2. Detailed Description of the Invention

[0029] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention. It should be understood that the terms used in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0030] In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0032] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0033] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open - ended terms, meaning including but not limited to.

[0034] The preparation method of 15% Mg-doped ZnMgO used in the following examples is as follows: 3 mmol of zinc acetate and magnesium acetate (the molar ratio of the two is 17:3) are dissolved in 30 ml of dimethyl sulfoxide (DMSO), and 4.5 mmol of tetramethylammonium hydroxide (TMAH) is dissolved in 10 ml of ethanol. The ethanol solution of TMAH is added dropwise to the DMSO solution of zinc acetate and magnesium acetate, and after reacting for 1 h, separation and purification are carried out.

[0035] Unless otherwise specified, other raw materials are commercially available conventional raw materials and are not particularly limited; the room temperature is 25 - 35 °C. This will not be repeated below.

[0036] Example 1

[0037] For the preparation of an anode-modified quantum dot light-emitting diode device, the steps are as follows:

[0038] (1) Cleaning and pretreatment of the ITO surface: The ITO glass substrate is ultrasonically treated in a cleaning agent solution, deionized water, acetone, isopropanol, and ethanol for 30 min in sequence, and then placed in ethanol and heated to near boiling, and blown dry with an argon gas stream. After drying, it is placed in a plasma cleaner and treated for 10 min under the condition of a radio frequency power of 80 W to obtain a pretreated ITO glass substrate.

[0039] (2) Preparation of the hole injection layer: The carbazole phosphonic acid-based self-assembled molecule (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) is dissolved in ethanol to prepare a 2 mmol / L ethanol solution of 2PACz. The ethanol solutions of PEDOT:PSS and 2PACz are mixed in a volume ratio of 1:1 to obtain a mixed solution of PEDOT:PSS-2PACz. Take 40 μL of the mixed solution and spin-coat it on the oxygen plasma-treated ITO under the conditions of 4000 rpm and 30 s, and then anneal it at 130 °C for 20 min and then remove it and cool it to room temperature to prepare an HIL film with a thickness of 30 nm.

[0040] (3) Preparation of the hole transport layer: Prepare a chlorobenzene solution of 10 mg / ml poly(N-vinylcarbazole) (PVK), take 40 μL of the PVK solution, and spin-coat it on the HIL film under the conditions of 4000 rpm and 30 s, and then anneal it at 140 °C for 20 min and then remove it and cool it to room temperature to prepare an HTL film with a thickness of 30 nm.

[0041] (4) Preparation of the quantum dot light-emitting layer: Transfer the ITO substrate coated with the hole transport layer to a glove box, take 40 μL of a 15 mg / mL ZnCdS / ZnS quantum dot n-octane solution, and spin-coat it on the HTL film under the conditions of 2000 rpm and 30 s, and then anneal it at 100 °C for 5 min and then remove it and cool it to room temperature to prepare a QDs film with a thickness of 25 nm.

[0042] (5) Preparation of electron transport layer: Prepare an ethanol solution of 15% Mg-doped ZnMgO at 20 mg / mL. Take 40 μL of the ZnMgO solution and spin-coat it onto the QDs film at 2000 rpm for 30 s. After annealing at 100 °C for 20 min, remove it and cool it to room temperature to obtain an ETL film with a thickness of 35 nm.

[0043] (6) Preparation of metal electrode: Prepare an aluminum electrode with a thickness of 100 nm on the electron transport layer by vacuum evaporation.

[0044] Example 2

[0045] Same as Example 1, except that in step (2), "carbazole phosphonic acid self-assembled molecule 2PACz" is replaced with an equal amount of "carboxylic acid self-assembled molecule 3FBA", and other raw materials, dosages, and steps are the same as those in Example 1.

[0046] Example 3

[0047] Same as Example 1, except that in step (2), "carbazole phosphonic acid self-assembled molecule 2PACz" is replaced with an equal amount of "silane self-assembled molecule HF 17 DES", and other raw materials, dosages, and steps are the same as those in Example 1.

[0048] Comparative Example 1

[0049] Same as Example 1, except that in this comparative example, step (2) is: Preparation of hole injection layer: Mix PEDOT:PSS and ethanol solution in a volume ratio of 1:1 to obtain a mixed solution of PEDOT:PSS. Take 40 μL of the mixed solution and spin-coat it on the oxygen plasma-treated ITO. The spin-coating conditions are 4000 rpm for 30 s, and then anneal at 130 °C for 20 min, remove it, and cool it to room temperature to obtain a HIL film with a thickness of 30 nm.

[0050] Comparative Example 2

[0051] Same as Example 1, except that in this comparative example, step (2) is: Preparation of hole injection layer: Dissolve carbazole phosphonic acid self-assembled molecule (2-(9H-carbazol-9-yl)ethyl)phosphonic acid (2PACz) in ethanol to prepare an ethanol solution of 2 mmol / L 2PACz. Take 40 μL of the ethanol solution of 2PACz and spin-coat it on the oxygen plasma-treated ITO. The spin-coating conditions are 4000 rpm for 30 s, and then anneal at 130 °C for 20 min, remove it, and cool it to room temperature.

[0052] Table 1 shows the electroluminescence performance parameters of the quantum dot light-emitting diode devices prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0053] Table 1 Electroluminescence performance parameters of the quantum dot light-emitting diode devices prepared in Example 1 and Comparative Examples 1-2

[0054]

[0055] Figure 1 For the quantum dot light-emitting diode device prepared in Example 1 ( Figure 1 in which, PEDOT:PSS-SAM QLED represents the quantum dot light-emitting diode device prepared in Example 1), the electroluminescence performance. It can be seen from Figure 1 that for the device prepared in Example 1, the emission peak of the electroluminescence spectrum is stable at 455 nm as the voltage increases, and the addition of 2PACz has no effect on the electroluminescent emission peak of the QLED device.

[0056] Figure 2 For the luminance-voltage-current density curves of the quantum dot light-emitting diode devices prepared in Example 1 and Comparative Examples 1 and 2 ( Figures 2 to 4 in which, PEDOT:PSS-SAM represents the quantum dot light-emitting diode device prepared in Example 1, PEDOT:PSS represents the quantum dot light-emitting diode device prepared in Comparative Example 1, and SAM represents the quantum dot light-emitting diode device prepared in Comparative Example 2), it can be seen from Figure 2 that in Example 1, PEDOT:PSS is doped with 2PACz as the hole injection layer, and the luminance of the device is significantly improved compared with Comparative Examples 1 and 2, and the maximum luminance can reach 10119.44 cd / m 2 , and the turn-on voltage is also significantly lower than that of Comparative Example 1.

[0057] Figure 3 For the current efficiency-luminance curves of the quantum dot light-emitting diode devices prepared in Example 1 and Comparative Examples 1 and 2, it can be seen from Figure 3 that in Example 1, PEDOT:PSS is doped with 2PACz as the hole injection layer, and the maximum current efficiency of the device can reach 6.13 cd / A.

[0058] Figure 4 For the external quantum efficiency-luminance curves of the quantum dot light-emitting diode devices prepared in Example 1 and Comparative Examples 1 and 2, it can be seen from Figure 4 that in Example 1, PEDOT:PSS is doped with 2PACz as the hole injection layer, which can increase the maximum external quantum efficiency of the deep blue light quantum dot light-emitting device to 18.33%, and the efficiency roll-off is slow.

[0059] It can be seen from the above performance data that when PEDOT:PSS is doped with 2PACz as the hole injection layer, the maximum luminance of the device can be increased to 10119.44 cd / m2 , the maximum current efficiency and the maximum external quantum efficiency can be respectively increased to 6.13 cd / A and 18.33%, and the efficiency roll-off is slow, so the device performance is significantly improved.

[0060] The above performances of the quantum dot light-emitting diode devices based on anode modification prepared in Examples 2 to 3 are comparable to those in Example 1.

[0061] The above is only the preferred specific implementation manner of the present invention, and the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, should be covered by the protection scope of the present invention.

Claims

1. A quantum dot light emitting diode based on anode modification, characterized in that, It includes an anode, a cathode, and a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, and an electron transport layer sequentially disposed between the anode and the cathode; the raw material of the hole injection layer is PEDOT:PSS doped with self-assembled molecules.

2. The quantum dot light-emitting diode based on anode modification according to claim 1, wherein The HOMO energy level of the PEDOT:PSS is -5.2 eV, and the self-assembled molecules include one or more of phosphonic acid-based self-assembled molecules, carboxylic acid-based self-assembled molecules, and silane-based self-assembled molecules.

3. The quantum dot light-emitting diode based on anode modification according to claim 2, wherein The phosphonic acid-based self-assembled molecules include one or more of (2-(9H-carbazol-9-yl)ethyl)phosphonic acid, [2-(3,6-diphenyl-9H-carbazol-9-yl)ethyl]phosphoric acid, [2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid, [2-(3,6-difluoro-9H-carbazol-9-yl)ethyl]phosphoric acid, [2-(3,6-dichloro-9H-carbazol-9-yl)ethyl]phosphoric acid, [2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphoric acid, (4-(9H-carbazol-9-yl)ethyl)phosphonic acid, [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid, [4-(3,6-dimethoxy-9H-carbazol-9-yl)butyl]phosphonic acid, [4-(7H-dibenzo[c,g]carbazol-7-yl)butyl]phosphonic acid, phenylphosphonic acid, 3,4,5-trifluorobenzylphosphoric acid, 2,3,4,5,6-pentafluorobenzylphosphoric acid, 4-trifluoromethylbenzylphosphoric acid, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecylphosphoric acid, and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-henicosafluorododecylphosphoric acid; the carboxylic acid-based self-assembled molecules include one or more of benzoic acid, 4-biphenylcarboxylic acid, 4-trifluoromethyl-benzoic acid, 4'-trifluoromethyl-biphenyl-4-carboxylic acid, anthracene carboxylic acid, fluorene-4-carboxylic acid, and 9-H-carbazole-2-carboxylic acid; the silane-based self-assembled molecules include one or more of 3,3,3-trifluoropropyltrimethoxysilane, perfluorooctyltriethoxysilane, and perfluorodecyltriethoxysilane.

4. A preparation method of a quantum dot light-emitting diode based on anode modification according to any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Clean and pre-treat the anode material with a substrate. (2) Preparation of the hole injection layer: Dissolve the self-assembled molecules in ethanol to obtain a self-assembled molecule ethanol solution, then mix it with PEDOT:PSS to obtain a mixed solution, and then spin-coat it on the anode material pretreated in step (1), anneal and cool to obtain a hole injection layer thin film. (3) Preparation of the hole transport layer: Configure a chlorobenzene solution of poly(N-vinylcarbazole) or a chlorobenzene solution of poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)], spin-coat it on the hole injection layer thin film obtained in step (2), anneal and cool to obtain a hole transport layer thin film. (4) Preparation of quantum dot light-emitting layer: Take a ZnCdS / ZnS quantum dot octane solution or a CdSe / ZnS quantum dot octane solution, spin-coat it onto the hole-transporting layer film obtained in step (3), anneal and cool to obtain a quantum dot light-emitting layer film; (5) Preparation of electron-transporting layer: Take a ZnMgO ethanol solution or a ZnO ethanol solution, spin-coat it onto the quantum dot light-emitting layer film obtained in step (4), anneal and cool to obtain an electron-transporting layer film; (6) Preparation of cathode: Prepare a metal electrode on the electron-transporting layer film obtained in step (5) by vacuum evaporation.

5. The preparation method according to claim 4, characterized in that, In step (1), the anode material is ITO; plasma pretreatment is adopted; in step (2), the concentration of the self-assembled molecule ethanol solution is 1 - 3 mmol / L, the volume ratio of PEDOT:PSS to the self-assembled molecule ethanol solution in the hole injection layer is 1:1, the annealing temperature is 120 - 140 °C, the time is 15 - 30 min, and the thickness of the hole injection layer film is 20 - 40 nm; in step (3), the concentrations of the poly(N-vinylcarbazole) chlorobenzene solution and the poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] chlorobenzene solution are both 6 - 12 mg / mL, the annealing temperature is 130 - 140 °C, the time is 15 - 30 min, and the thickness of the hole-transporting layer film is 20 - 40 nm.

6. The preparation method according to claim 4, characterized in that, In step (4), the concentrations of the ZnCdS / ZnS quantum dot octane solution and the CdSe / ZnS quantum dot octane solution are both 12 - 18 mg / mL, the annealing temperature is 80 - 100 °C, the time is 3 - 6 min, and the thickness of the quantum dot light-emitting layer film is 20 - 30 nm; in step (5), the concentrations of the ZnMgO ethanol solution and the ZnO ethanol solution are both 15 - 20 mg / mL, the annealing temperature is 80 - 100 °C, the time is 15 - 30 min, and the thickness of the electron-transporting layer film is 30 - 40 nm; in step (6), the metal electrode includes a metal aluminum electrode with a thickness of 80 - 100 nm.

7. Application of the anode-modified quantum dot light-emitting diode according to any one of claims 1 - 3 in the display field.

8. The application according to claim 7, wherein Specifically, it includes applications in mobile phones, laptop computers, tablet computers, smart watches, smart TVs, and VR technology.

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