WO2021129710A1 - Preparation method for quantum dot light emitting diode - Google Patents

Abstract

The present application discloses a preparation method for a quantum dot light emitting diode. The preparation method comprises the following steps for preparing a carrier transport layer: providing a base, a quantum dot light emitting layer being formed on the base; providing a ligand solution, the ligand solution containing: at least one of an ammonium salt, an organic amine, an ester compound and a phenolic compound; depositing the ligand solution on the quantum dot light emitting layer to prepare a quantum dot light emitting layer with a ligand modified on the surface thereof; and providing a carrier transport layer ink, and depositing the carrier transport layer ink on the quantum dot light emitting layer with a ligand modified on the surface thereof, so as to prepare a carrier transport layer. Modifying the surface of a quantum dot light emitting layer increases the interface compatibility between the carrier transport layer ink and the quantum dot light emitting layer, and improves the film-forming property of the carrier transport layer.

Description

Method for preparing quantum dot light-emitting diode

This application claims the priority of the Chinese patent application filed at the Chinese Patent Office on December 27, 2019, with the application number 201911378994.X and the invention title "Method for Preparation of Quantum Dot Light Emitting Diodes", the entire content of which is incorporated by reference In this application.

Technical field

This application relates to the field of display technology, in particular to a method for preparing quantum dot light-emitting diodes.

Background technique

Quantum Dots Light Emitting Diode (QLED) is a flat panel display device that emits light from excitons in a quantum dot material driven by an external electric field. It has the advantages of color cell harmony, high purity, good monochromaticity, and adjustable color. It solves the problem of organic light-emitting diodes ( The organic light-emitting materials in OLED), the color is not adjustable, the half-peak width is wider, the production cost is high, and the operation process is complicated. It is an ideal choice for the next generation of flat panel displays and solid state lighting.

The device structure of QLED is a typical sandwich structure, mainly composed of a cathode, an anode, and a quantum dot light-emitting layer sandwiched between the cathode and the anode. In addition, between the anode and the quantum dot light-emitting layer and/or the cathode and the quantum dot light-emitting layer There are often thin functional layers such as carrier transport layer, carrier injection layer and carrier blocking layer between them. Magnetron sputtering, evaporation, chemical vapor deposition, atomic layer deposition, molecular layer deposition, etc. can be used. Inkjet printing and other techniques are used for preparation.

Because inkjet printing has the advantages of fast printing speed, low noise, low price, environmental protection, and precise control of film thickness, it has been widely used in the manufacturing process of quantum dot light-emitting diodes in recent years. In the process of preparing QLEDs using inkjet printing and film forming technology, it is often necessary to disperse the thin layer of material to be printed in a solvent to prepare printing ink, and then print the ink on a set area, for example: the carrier transport layer ink It is printed on the set area of the quantum dot light-emitting layer and cured to obtain a carrier transport layer. In order to avoid mutual dissolution between the quantum dot luminescent material and the carrier transport layer ink during the inkjet printing process, the solvent of the carrier transport layer ink often uses a polar solvent with the opposite polarity to the quantum dot luminescent material. However, due to the large difference in polarity between the carrier transport layer ink and the quantum dot luminescent material, the carrier transport layer ink is not easy to coat on the quantum dot luminescent layer. The poor performance of the film results in the low lifetime and luminous efficiency of QLEDs.

technical problem

One of the purposes of the embodiments of the present application is to provide a method for preparing quantum dot light-emitting diodes, which aims to solve the poor performance of the carrier transport layer in the existing methods, resulting in the generally low lifespan and luminous efficiency of QLEDs The problem.

Technical solutions

In order to solve the above technical problems, the technical solutions adopted in the embodiments of this application are:

In the first aspect, a method for preparing a quantum dot light-emitting diode is provided, which includes the following steps of preparing a carrier transport layer:

Providing a matrix on which a quantum dot light-emitting layer is formed;

Provide a ligand solution, the ligand solution comprising: at least one of ammonium salts, organic amines, ester compounds, and phenolic compounds; depositing the ligand solution on the quantum dot light-emitting layer to prepare a surface modification Quantum dot light-emitting layer with ligand;

A carrier transport layer ink is provided, and the carrier transport layer ink is deposited on the quantum dot light-emitting layer whose surface is modified with a ligand to prepare a carrier transport layer.

In one embodiment, the ammonium salt is selected from ammonium halides and/or tetramethylammonium hydroxide.

In one embodiment, the organic amine is selected from at least one of ethylenediamine, aniline and triethanolamine.

In one embodiment, the ester compound is selected from at least one of methyl methacrylate, ethyl crotonate, ethyl acetate and methyl benzoate.

In one embodiment, the phenolic compound is selected from at least one of phenol, catechol, and 1-hydroxy-naphthalene.

In an embodiment, the weight percentage concentration of the ligand in the ligand solution is 0.0001%-1%.

In one embodiment, the material of the quantum dot light-emitting layer is oil-soluble quantum dots, and the solvent of the ligand solution is alcohol.

In one embodiment, the alcohol includes at least one of ethanol, propanol, and butanol.

In one embodiment, in the step of depositing the ligand solution on the quantum dot light-emitting layer, the quantum dot light-emitting layer is immersed in the ligand solution, and immersed in the ligand solution for a preset time. The volume solution is separated, and the solvent on the surface of the quantum dot light-emitting layer is removed.

In an embodiment, the temperature at which the quantum dot light-emitting layer is immersed in the ligand solution is -5°C to 100°C.

In one embodiment, the carrier transport layer is an electron transport layer.

In one embodiment, the matrix includes: an anode, the quantum dot light-emitting layer is formed on the anode, and a hole transport layer and/or hole injection layer is formed between the anode and the quantum dot light-emitting layer Floor.

In one embodiment, the preparation method further includes: depositing a cathode on the electron transport layer.

In one embodiment, the preparation method further includes: depositing an electron injection layer on the electron transport layer, and depositing a cathode on the electron injection layer.

In one embodiment, in the quantum dot light emitting diode, the carrier transport layer is a hole transport layer.

In one embodiment, the substrate includes a cathode on which the quantum dot light-emitting layer is formed, and an electron transport layer and/or an electron injection layer is formed between the cathode and the quantum dot light-emitting layer.

In an embodiment, the preparation method further includes: depositing an anode on the hole transport layer.

In one embodiment, the preparation method further includes: depositing a hole injection layer on the hole transport layer, and depositing an anode on the hole injection layer.

In the second aspect, a quantum dot light-emitting diode prepared by the above preparation method is provided.

Beneficial effect

The method for preparing quantum dot light-emitting diodes provided in this application uses ammonium salts, organic amines, ester compounds, and phenolic compounds as the active ingredients of the ligand solution, and deposits the ligand solution on the quantum dot light-emitting layer to The quantum dot light-emitting layer whose surface is modified with ligand is prepared. In the inkjet printing method, a polar solvent with the opposite polarity to the material of the quantum dot light-emitting layer is often used to avoid mutual dissolution between the quantum dot light-emitting layer material and the intercepting sub-transport layer ink during the inkjet printing process. This application adopts ammonium salt , Organic amines, ester compounds and phenolic compounds and other active ingredients surface modification of the quantum dot light-emitting layer, which can make the surface of the quantum dot light-emitting layer connected with polar ligands, thereby increasing the carrier transport layer ink and the quantum dot light-emitting layer The interface compatibility between these promotes the carrier transport layer ink to form a uniform film layer on the quantum dot light-emitting layer, thereby improving the film-forming performance of the carrier transport layer, thereby increasing the lifespan and luminous efficiency of the QLED.

The quantum dot light-emitting diode provided by the present application is prepared by the above-mentioned preparation method and has a longer life and higher luminous efficiency.

Description of the drawings

In order to more clearly describe the technical solutions in the embodiments of the present application, the following will briefly introduce the accompanying drawings that need to be used in the embodiments or exemplary technical descriptions. Obviously, the accompanying drawings in the following description are only of the present application. For some embodiments, those of ordinary skill in the art can obtain other drawings based on these drawings without creative work.

FIG. 1 is a flowchart of a method for manufacturing a quantum dot light-emitting diode provided by an embodiment of the present application;

2 is a schematic structural diagram of a substrate used in a method for manufacturing a quantum dot light-emitting diode provided by an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a substrate used in a method for manufacturing a quantum dot light-emitting diode provided by an embodiment of the present application; FIG.

4 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the method for manufacturing a quantum dot light-emitting diode according to an embodiment of the present application;

5 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the manufacturing method provided by the embodiment of the present application;

6 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the manufacturing method provided by the embodiment of the present application;

FIG. 7 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the manufacturing method provided by the embodiment of the present application;

FIG. 8 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the manufacturing method provided in the embodiment of the present application;

FIG. 9 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the manufacturing method provided by the embodiment of the present application;

FIG. 10 is a schematic structural diagram of a quantum dot light-emitting diode manufactured by the manufacturing method provided by the embodiment of the present application.

Embodiments of the present invention

In order to make the purpose, technical solutions, and advantages of this application clearer and clearer, the following further describes the application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, and are not used to limit the present application.

In order to solve the problem of poor film performance of the carrier transport layer in the existing methods, resulting in the generally low lifespan and luminous efficiency of QLEDs, the embodiments of the present application provide the following specific technical solutions:

A method for preparing a quantum dot light-emitting diode, as shown in FIG. 1, includes the following steps of preparing a carrier transport layer:

S01. Provide a substrate, on which a quantum dot light-emitting layer is formed;

S02. Provide a ligand solution, the ligand solution comprising: at least one of ammonium salts, organic amines, ester compounds and phenolic compounds; depositing the ligand solution on the quantum dot light-emitting layer to prepare Quantum dot light-emitting layer modified with ligand on the surface;

S03. Provide a carrier transport layer ink, and deposit the carrier transport layer ink on the quantum dot light-emitting layer whose surface is modified with a ligand to prepare a carrier transport layer.

The method for preparing quantum dot light-emitting diodes provided in the embodiments of the application uses ammonium salts, organic amines, ester compounds, and phenolic compounds as the active ingredients of the ligand solution, and deposits the ligand solution on the quantum dot light-emitting layer , To prepare a quantum dot light-emitting layer modified with ligands on the surface. In the inkjet printing method, a polar solvent with the opposite polarity to the material of the quantum dot light-emitting layer is often used to avoid mutual dissolution between the quantum dot light-emitting layer material and the intercepting sub-transport layer ink during the inkjet printing process. Active ingredients such as ammonium salts, organic amines, ester compounds, and phenolic compounds modify the quantum dot light-emitting layer on the surface, which can connect the surface of the quantum dot light-emitting layer with polar ligands, thereby increasing the carrier transport layer ink and quantum dots The interface compatibility between the light-emitting layers promotes the carrier transport layer ink to form a uniform film on the quantum dot light-emitting layer, thereby improving the film-forming performance of the carrier transport layer, thereby increasing the lifespan and luminous efficiency of the QLED.

Specifically, in step S01, a quantum dot light-emitting layer is formed on the substrate as a carrier to promote subsequent surface modification of the quantum dot light-emitting layer. The structure of the substrate can refer to the substrates of conventional light-emitting diodes in the art, and the embodiments of the present application will not be repeated here.

The material of the quantum dot light-emitting layer is oily quantum dots, including, but not limited to, II-VI group compound quantum dots, III-V group compound quantum dots, and IV-VI group compound quantum dots. In some embodiments, the thickness of the quantum dot light-emitting layer is 30-50 nm.

Specifically, in step S02, the ligand solution contains: at least one of ammonium salts, organic amines, ester compounds, and phenolic compounds, and ammonium salts, organic amines, ester compounds, and phenolic compounds are used as the ligand solution. The active ingredient is used to modify the surface of the quantum dot light-emitting layer so that the surface of the quantum dot light-emitting layer is connected with polar ligands, reducing the polarity gap between the quantum dot light-emitting layer and the carrier transport layer, thereby increasing The interface compatibility between the carrier transport layer ink and the quantum dot light-emitting layer is improved, the interface bonding degree between the carrier transport layer and the quantum dot light-emitting layer is improved, and the film-forming performance of the carrier transport layer is improved.

Among them, the ammonium salt is preferably ammonium halide. In some embodiments, the ammonium halide is selected from at least one of ammonium fluoride, ammonium fluoride, and ammonium iodide. These ammonium halides contain ammonium ions, which can coordinately connect with the quantum dot metal vacancies on the surface of the quantum dot light-emitting layer, and have good adhesion. After testing, the quantum dots that have undergone surface modification treatment with these ammonium halide ethanol solutions The carrier transport layer deposited on the light-emitting layer has good film-forming properties.

The organic amine is an organic substance containing an amine group. In some embodiments, the organic amine is selected from at least one of ethylenediamine, aniline, and triethanolamine. This organic amine contains amine groups. The amine groups can be bound to the surface of the quantum dot light-emitting layer through coordination bonds, which can improve the polarity of the quantum dot light-emitting layer surface to a certain extent, and improve the surface of the quantum dot light-emitting layer and the carrier transport layer ink The compatibility between the two is conducive to improving the film performance of the carrier transport layer.

The ester compound is an organic substance containing an ester group. In some embodiments, the ester compound is selected from at least one of methyl methacrylate, ethyl crotonate, ethyl acetate, and methyl benzoate. The ester compound can be stably modified on the surface of the quantum dot light-emitting layer, and can be used as a buffer layer between the quantum dot light-emitting layer and the carrier transport layer, which is beneficial to improve the compatibility between the quantum dot light-emitting layer and the carrier transport layer ink , Improve the film performance of the carrier transport layer.

The phenolic compound is an organic substance containing a phenolic group. In some embodiments, the phenolic compound is selected from at least one of phenol, catechol, and 1-hydroxy-naphthalene. After testing, the surface of the quantum dot is modified with the above-mentioned factors. This kind of phenolic compound is beneficial to improve the film performance of the carrier transport layer.

As an embodiment, the ligand solution contains: ammonium halide, ethylenediamine, tetramethylammonium hydroxide, aniline, triethanolamine, methyl methacrylate, ethyl crotonate, ethyl acetate, methyl benzoate One of phenol, catechol, and 1-hydroxy-naphthalene. In some embodiments, the solvent of the ligand solution is alcohol, ammonium halide, ethylenediamine, tetramethylammonium hydroxide, aniline, triethanolamine, methyl methacrylate, ethyl crotonate, ethyl acetate, benzene Methyl formate, phenol, catechol, and 1-hydroxy-naphthalene have good solubility in alcohol, and alcohol is volatile, and the solvent on the surface of the light-emitting layer can be quickly removed after the surface modification treatment step is completed. Ensure that no solvent remains on the surface of the quantum dot light-emitting layer. In a further embodiment, the alcohol includes at least one of ethanol, propanol, and butanol.

In order to avoid the mutual dissolution of the quantum dot light-emitting layer material and the intercepting sub-transport layer ink during the inkjet printing process, a polar solvent with the opposite polarity to the quantum dot light-emitting layer material is often used in the inkjet printing method. For the same reason, in this application In the embodiment, the polarity of the ligand solution is opposite to the polarity of the quantum dot light-emitting layer material. Due to the limitation of the existing technology, most of the current quantum dot luminescent materials are mainly oil-soluble quantum dots. Therefore, polar or hydrophilic inks are often used for inkjet printing of the carrier transport layer.

As an embodiment, the quantum dot light-emitting layer material is oil-soluble quantum dots, and the solvent of the ligand solution is alcohol. Alcohol has the characteristics of being volatile, and after the surface modification treatment step is completed, the solvent on the surface of the light-emitting layer can be quickly removed to ensure no solvent residue on the surface of the quantum dot light-emitting layer. In a further embodiment, the alcohol includes at least one of ethanol, propanol, and butanol.

The ligand solution uses ammonium salts, organic amines, ester compounds and phenolic compounds as solutes, and the concentration of the solute affects the surface modification effect of the quantum dot light-emitting layer. As an embodiment, the concentration of the solute in the ligand solution is 0.0001%-1%. Ammonium salts and organic amines have the advantages of strong polarity, easy reaction, and easy decomposition at high temperature. They are excellent materials for modifying the quantum dot layer. However, because quantum dots are too sensitive to materials, they also have the disadvantage that the reaction is difficult to control; esters The compounds and phenolic compounds are slightly weaker in polarity, with moderate reactivity and moderate volatility, but because the reaction is relatively controllable, they also have certain application value. The effective concentration of the solute in the ligand solution is generally within the range of 0.0001%-1%. Too high can easily lead to high solute residues, cause surface defects of the functional layer, and reduce device efficiency; too low can easily lead to limited effects.

In step S02, the ligand solution is deposited on the quantum dot light-emitting layer, so that the active ingredient in the solvent is attached to the surface of the quantum dot light-emitting layer in the form of ions or compounds, thereby obtaining a quantum dot whose surface is modified with ligand. Point light-emitting layer.

In the step of depositing the ligand solution on the quantum dot light-emitting layer, conventional deposition methods, such as spin coating, inkjet printing, etc., can be used, and other methods can also be used.

As an embodiment, in the step of depositing the ligand solution on the quantum dot light-emitting layer, the quantum dot light-emitting layer is immersed in the ligand solution, and immersed in the ligand solution for a preset time. The volume solution is separated, and the solvent on the surface of the quantum dot light-emitting layer is removed.

By using the immersion method to deposit the ligand solution on the surface of the quantum dot light-emitting layer, the ligand can be modified on the surface of the quantum dot light-emitting layer, without expensive equipment, simple operation, simplifying the process, and promoting the large-scale mass production of quantum dot light-emitting diodes. lower the cost.

The temperature and time for immersing the quantum dot light-emitting layer in the ligand solution can be flexibly adjusted according to the actual needs of the product. In some embodiments, the quantum dot light-emitting layer is immersed in the ligand solution The temperature is -5℃-100℃. The reaction barrier of the ligand-modified quantum dots determines the temperature of the immersion solution. Controlling the temperature is conducive to controlling the reaction speed and reaction time, so as to achieve the ideal process effect. In some embodiments, the time for immersing the quantum dot light-emitting layer in the ligand solution is less than 10 minutes.

Specifically, in step S03, the carrier transport layer ink is deposited on the quantum dot light-emitting layer whose surface is modified with ligands to prepare a carrier transport layer.

The carrier transport layer ink is a solution in which the carrier transport layer material is dissolved, and includes the carrier transport layer material and a solvent for dispersing the carrier transport layer material. In order to avoid miscibility with the quantum dot light-emitting layer material, the solvent of the carrier transport layer ink is often opposite in polarity to the quantum dot light-emitting layer material. The carrier transport layer material is selected from conventional carrier transport layer materials in the field, and may be a commercially available product, or it may be prepared by conventional operations in the field. It can be understood that the carrier transport layer is an electron transport layer or a hole transport layer. In some embodiments, the carrier transport layer is an electron transport layer, and the electron transport layer material is selected from n-type zinc oxide. In some embodiments, the carrier transport layer is a hole transport layer, and the hole transport layer material is selected from poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl) ) Diphenylamine) (TFB), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), NiO, At least one of MoO3.

For the step of depositing the carrier transport layer ink on the quantum dot light-emitting layer modified with ligands, reference may be made to conventional operations in the art, such as spin coating or inkjet printing. In some embodiments, an inkjet printing method is used to print the carrier transport layer ink on the predetermined area of the surface-modified quantum dot light-emitting layer. In some embodiments, the thickness of the carrier transport layer is 10-100 nm.

As an embodiment, the carrier transport layer is an electron transport layer; as shown in FIG. 2, the matrix includes: an anode, a quantum dot light-emitting layer is formed on the anode, and a hole transport layer is formed between the anode and the quantum dot light-emitting layer And/or hole injection layer. The hole injection layer material can refer to conventional hole injection layer materials in the art, such as PEDOT:PSS. In some other embodiments, the hole injection layer has a thickness of 10-100 nm.

Correspondingly, in some embodiments, the preparation method further includes: depositing a cathode on the electron transport layer; or

The preparation method further includes: depositing an electron injection layer on the electron transport layer, and depositing a cathode on the electron injection layer.

As an embodiment, the carrier transport layer is a hole transport layer; as shown in FIG. 3, the matrix includes: a cathode, a quantum dot light-emitting layer is formed on the cathode, and an electron transport layer is formed between the cathode and the quantum dot light-emitting layer And/or electron injection layer. The material of the electron injection layer can refer to the conventional electron injection layer materials in the art, such as LiF, CsF, etc. In some other embodiments, the thickness of the electron injection layer is 10-100 nm.

Correspondingly, the preparation method further includes: depositing an anode on the hole transport layer; or

The preparation method further includes: depositing a hole injection layer on the hole transport layer, and depositing an anode on the hole injection layer.

In the embodiments of the present application, the materials and thicknesses of the anode and cathode can refer to the anode and cathode of conventional quantum dot light-emitting diodes in the art. In some embodiments, the anode is selected as an indium tin oxide (ITO) electrode with a thickness of 60-120 nm. In some embodiments, the cathode is selected as an Ag or Al electrode with a thickness of 60-120 nm.

In summary, under the combined effect of the multiple optimized process conditions provided in the embodiments of the present application, the interface between the carrier transport layer and the quantum dot light-emitting layer is tightly bonded, and the film of the carrier transport layer The layer performance is good, so that the quantum dot light-emitting diode obtained by the preparation method provided in the embodiment of the present application has a longer life and higher luminous efficiency.

Compared with the traditional method of first modifying the surface of a quantum dot material and then forming a quantum dot light-emitting layer, the embodiment of the present application adopts a method of immersing the quantum dot light-emitting layer in a ligand solution containing a polar ligand for surface modification. Simplified and easy to operate, it can greatly improve production efficiency and realize large-scale mass production.

Correspondingly, the quantum dot light-emitting diode prepared by the above preparation method.

The quantum dot light-emitting diode provided by the embodiment of the present application is produced by the above-mentioned preparation method and has a longer life and higher luminous efficiency.

As an embodiment, as shown in FIG. 5, the quantum dot light-emitting diode includes a substrate, a first electrode, a quantum dot light-emitting layer, an electron transport layer, and a second electrode arranged in sequence.

As an embodiment, as shown in FIG. 6, the quantum dot light-emitting diode includes a substrate, a first electrode, a quantum dot light-emitting layer, an electron transport layer, an electron injection layer, and a second electrode arranged in sequence.

As an embodiment, as shown in FIG. 7, the quantum dot light-emitting diode includes a substrate, a first electrode, a quantum dot light-emitting layer, a hole transport layer, and a second electrode arranged in sequence.

As an embodiment, as shown in FIG. 8, the quantum dot light-emitting diode includes a substrate, a first electrode, a quantum dot light-emitting layer, a hole transport layer, a hole injection layer, and a second electrode arranged in sequence.

As an embodiment, as shown in FIG. 9, the quantum dot light-emitting diode includes a substrate, a first electrode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and electrons arranged in sequence. Injection layer and second electrode.

As an embodiment, as shown in FIG. 10, the quantum dot light-emitting diode includes: a substrate, a first electrode, an electron injection layer, an electron transport layer, a quantum dot light-emitting layer, a hole transport layer, and a hole Injection layer and second electrode.

In order to illustrate the technical solutions provided by the present application, detailed descriptions are given below in conjunction with specific drawings and embodiments.

Example 1

This embodiment provides a method for manufacturing a quantum dot light-emitting diode, which specifically includes the following steps:

S11, forming a CdSe/ZnS quantum dot light-emitting layer on the substrate, the substrate in turn includes: a glass substrate, an ITO anode, a PEDOT:PSS hole injection layer and a TFB hole transport layer;

S12. Immerse the quantum dot light-emitting layer in the ethyl crotonate-ethanol solution, take out the device, and dry to obtain a quantum dot light-emitting layer that has been surface-modified by ethyl crotonate;

S13. Using inkjet printing technology, print a ZnO electron transport layer ink on the surface-modified quantum dot light-emitting layer to prepare a ZnO electron transport layer;

S14, forming a LiF electron injection layer and an Al cathode in sequence on the ZnO electron transport layer.

In the preparation methods provided in Example 2-6 and Comparative Example 1-2, the difference from Example 1 is that the selected ligand solution is different, and the specific information is shown in Table 1.

Table 1

To	Solute	Solvent	Remarks
Comparative example 1	-	-	Step S12 is omitted
Comparative example 2	-	Ethanol	To
Example 1	Ethyl crotonate	Ethanol	To
Example 2	phenol	Ethanol	To
Example 3	aniline	Propanol	To
Example 4	Methyl benzoate	Propanol	To
Example 5	Ammonium fluoride	Ethanol	To
Example 6	Ethylenediamine	Ethanol	To

Test case 1

The quantum dot light-emitting diodes prepared in Examples 1-6 and Comparative Examples 1-2 were taken to test the changes in external quantum efficiency (EQE, %), and the test results are shown in Table 2. The results showed that the external quantum efficiency of the quantum dot light-emitting diodes prepared in Examples 1-6 was significantly improved after 6 days of use.

Table 2

To	1 day later	2 days later	3 days later	4 days later	5 days later	6 days later
Comparative example 1	8.8	10.5	11.0	11.3	11.3	11.4
Comparative example 2	8.6	10.4	10.8	11.0	11.1	11.0
Example 1	6.7	7.7	8.5	10.2	11.6	12.0
Example 2	10.0	10.3	10.7	11.0	13.0	13.3
Example 3	6.5	8.8	10.3	10.6	11.1	11.6
Example 4	7.2	9.1	10.3	11.4	12.1	11.0
Example 5	11.0	12.5	13.1	13.5	13.8	14.1
Example 6	9.7	12.1	12.8	13.0	13.3	13.3

Test case 2

The quantum dot light-emitting diodes prepared in Examples 1-6 and Comparative Examples 1-2 were taken to test their service life respectively, and the test results are shown in Table 3. The results show that the lifetime of the quantum dot light-emitting diodes prepared in Examples 1-6 is significantly increased.

table 3

To	Device life (h)
Comparative example 1	632
Comparative example 2	684
Example 1	709
Example 2	749
Example 3	725
Example 4	773
Example 5	853
Example 6	760

The above are only optional embodiments of the application, and are not used to limit the application. For those skilled in the art, this application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the scope of the claims of this application.

Claims (19)

1. A method for preparing a quantum dot light-emitting diode is characterized in that it comprises the following steps of preparing a carrier transport layer:

   Providing a matrix on which a quantum dot light-emitting layer is formed;

   Provide a ligand solution, the ligand solution comprising: at least one of ammonium salts, organic amines, ester compounds, and phenolic compounds; depositing the ligand solution on the quantum dot light-emitting layer to prepare a surface modification Quantum dot light-emitting layer with ligand;

   A carrier transport layer ink is provided, and the carrier transport layer ink is deposited on the quantum dot light-emitting layer whose surface is modified with a ligand to prepare a carrier transport layer.
2. The preparation method according to claim 1, wherein the ammonium salt is selected from ammonium halides and/or tetramethylammonium hydroxide.
3. The preparation method according to claim 1, wherein the organic amine is selected from at least one of ethylenediamine, aniline and triethanolamine.
4. The preparation method according to claim 1, wherein the ester compound is selected from at least one of methyl methacrylate, ethyl crotonate, ethyl acetate and methyl benzoate.
5. The preparation method according to claim 1, wherein the phenolic compound is selected from at least one of phenol, catechol, and 1-hydroxy-naphthalene.
6. The preparation method according to claim 1, wherein the weight percentage concentration of the ligand in the ligand solution is 0.0001%-1%.
7. The preparation method according to claim 1, wherein the material of the quantum dot light-emitting layer is oil-soluble quantum dots, and the solvent of the ligand solution is alcohol.
8. The preparation method according to claim 7, wherein the alcohol comprises at least one of ethanol, propanol and butanol.
9. The preparation method according to claim 1, wherein in the step of depositing the ligand solution on the quantum dot light-emitting layer, the quantum dot light-emitting layer is immersed in the ligand solution and immersed After a preset time, separate from the ligand solution, and remove the solvent on the surface of the quantum dot light-emitting layer.
10. The preparation method according to claim 9, wherein the temperature at which the quantum dot light-emitting layer is immersed in the ligand solution is -5°C to 100°C.
11. The preparation method according to claim 1, wherein the carrier transport layer is an electron transport layer.
12. The preparation method according to claim 11, wherein the substrate comprises: an anode, the quantum dot light-emitting layer is formed on the anode, and holes are formed between the anode and the quantum dot light-emitting layer Transport layer and/or hole injection layer.
13. The preparation method according to claim 11, wherein the preparation method further comprises: depositing a cathode on the electron transport layer.
14. The preparation method according to claim 11, wherein the preparation method further comprises: depositing an electron injection layer on the electron transport layer, and depositing a cathode on the electron injection layer.
15. The manufacturing method according to claim 1, wherein in the quantum dot light emitting diode, the carrier transport layer is a hole transport layer.
16. The preparation method according to claim 15, wherein the substrate comprises: a cathode, the quantum dot light-emitting layer is formed on the cathode, and electron transport is formed between the cathode and the quantum dot light-emitting layer. Layer and/or electron injection layer.
17. The preparation method according to claim 15, wherein the preparation method further comprises: depositing an anode on the hole transport layer.
18. The preparation method according to claim 15, wherein the preparation method further comprises: depositing a hole injection layer on the hole transport layer, and depositing an anode on the hole injection layer.
19. A quantum dot light-emitting diode prepared by the preparation method of any one of claims 1-18.