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

Abstract

The present invention provides a composite material, a preparation method thereof, and a quantum dot light-emitting diode and a preparation method thereof, relating to the display field. The composite material comprises quantum dots and MXenes, wherein the metal atoms of the quantum dots are connected to the surface groups of the MXenes via coordination bonds. Application of the composite material of the present invention to quantum dot light-emitting diodes can increase the carrier injection rate and enhance the performance of the quantum dot light-emitting diodes.

Description

Technical Field

[0001] The present application relates to the display field, and specifically to a composite material and a preparation method thereof, a quantum dot light emitting diode and a preparation method thereof. Background Art

[0002] Today's mainstream display technology is LCD, which requires a backlight. However, existing backlight technology suffers from numerous limitations, including high power consumption, complex structural processes, and high costs. To address these issues, quantum dots, with their excellent optical properties, such as continuously adjustable full-spectrum emission peaks, high color purity, and excellent stability, are being applied to backlight technology.

[0003] When quantum dots replace traditional phosphors, the color gamut of displays can be significantly improved. The application of quantum dots in backlight modules has shown that the color gamut of displays can be increased from 72% NTSC to 110% NTSC. Furthermore, when quantum dots are applied to active-matrix quantum dot light-emitting diode (ALD) displays, compared to traditional backlight LCDs, the self-luminous QDs offer more outstanding display effects in scenes such as black rendering and high brightness conditions, consume less power, and can adapt to a wider temperature range. Displays with a color gamut of up to 130% NTSC can also be produced.

[0004] Quantum dot light-emitting diodes (LEDs) offer excellent performance across all aspects, but parameters such as device efficiency and operational stability still fall short of the requirements for industrial application. In particular, the surfaces of quantum dots commonly used in displays are often coated with long oleic acid carbon chains, which hinder the movement of charge carriers and result in low carrier transport capacity in quantum dot LEDs. Therefore, an effective method is needed to address these issues. Summary of the Invention

[0005] The present invention aims to provide a composite material and a method for preparing the same, as well as a quantum dot light-emitting diode and a method for preparing the same, to improve the low carrier transport capacity of existing quantum dot light-emitting diodes and the limited application of quantum dots in optoelectronic devices. This objective is achieved through the following technical solutions.

[0006] The present invention provides a composite material comprising quantum dots and MXenes, wherein metal atoms of the quantum dots are connected to surface groups of the MXenes via coordination bonds.

[0007] Optionally, the surface groups of MXenes are one or more of hydroxyl groups and halogen groups.

[0008] Optionally, the quantum dots are selected from CdSe, ZnSe, PbSe, CdTe, InP, GaN, GaP, AlP, InN, ZnTe, InAs, GaAs, CaF2, Cd1-x Zn x S, Cd 1-x Zn x Se, CdSe y S 1-y 、PbSe y S 1-y 、Zn x Cd 1-x Te, CdS / ZnS, Cd 1-x Zn x S / ZnS、Cd 1-x Zn x Se / ZnSe、CdSe 1-x S x / CdSe y S 1-y / CdS、CdSe / Cd 1-x Zn x Se / Cd y Zn 1-y Se / ZnSe、Cd 1-x Zn x Se / Cd y Zn 1-y Se / ZnSe, CdS / Cd 1-x Zn x S / Cd y Zn 1-y S / ZnS, NaYF4, NaCdF4, Cd 1-x Zn x Se y S 1-y 、CdSe / ZnS、Cd 1-x Zn x Se / ZnS, CdSe / CdS / ZnS, CdSe / ZnSe / ZnS, Cd 1-x Zn x Se / Cd y Zn 1-y One or more of S / ZnS, InP / ZnS.

[0009] Optionally, the quantum dots are core-shell structured quantum dots, and the metal atoms are shell metal atoms of the core-shell structured quantum dots.

[0010] Accordingly, the present invention also provides a method for preparing a composite material, comprising the following steps:

[0011] mixing a first organic solvent in which quantum dots are dispersed with MXenes for reaction;

[0012] After solid-liquid separation, a composite material is obtained.

[0013] Optionally, the molar ratio of quantum dots to MXenes is 1:0.05 to 0.5.

[0014] Optionally, the first organic solvent is an olefin or alkane with a boiling point of 280-400°C.

[0015] Optionally, the mixing reaction is carried out at 200-250° C. under protective gas conditions.

[0016] The present invention also provides a quantum dot light-emitting diode, comprising a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode, wherein the material of the light-emitting layer comprises a composite material;

[0017] Among them, the composite material includes quantum dots and MXenes, and the metal atoms of the quantum dots are connected to the surface groups of MXenes through coordination bonds.

[0018] Accordingly, the present invention also provides a method for preparing a quantum dot light-emitting diode, comprising the following steps:

[0019] providing a solution of the composite material dissolved in a solvent, wherein the solvent is an alkane-type non-polar solvent;

[0020] depositing a solution on the electron transport layer to form a light-emitting layer;

[0021] Alternatively, a solution is deposited on the hole transport layer to form a light-emitting layer;

[0022] Among them, the composite material includes quantum dots and MXenes, and the metal atoms of the quantum dots are connected to the surface groups of MXenes through coordination bonds.

[0023] Beneficial effects:

[0024] The present invention uses the above-mentioned composite material preparation method to compound MXenes with quantum dots to prepare the composite material MXenes-quantum dots. In the composite material, the quantum dots are attached to the two-dimensional MXenes nanosheets. When the light-emitting layer is prepared by this composite material, the agglomeration phenomenon in the film forming process can be improved, so that it has better light stability. In addition, when the light-emitting layer composite material is used to prepare a quantum dot light-emitting diode, after the quantum dots are attached to the wrinkled structure of MXenes, the composite material forms a fluorescence emission channel between the adjacent wrinkled structures of the MXenes nanosheets, so that the fluorescence emitted by the quantum dots can be reflected by the wrinkled wall and emitted outward through the fluorescence emission channel, which can improve the quantum efficiency of the device to a certain extent. At the same time, electrons are introduced into the light-emitting layer through the electron transport layer. Under the action of the MXenes quantum confinement effect, the light-emitting layer has good carrier transport capacity, and the carriers pass through the M n+1 X n T zThe surface groups of MXenes nanosheets, such as -OH and -F, are transferred to quantum dots, which enhances the luminescence efficiency of the device and improves the performance of quantum dot light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 This is a schematic structural diagram of a positive-type quantum dot light-emitting diode provided in Example 7 of the present application;

[0027] Figure 2 This is a schematic structural diagram of an inverted quantum dot light-emitting diode provided in Example 10 of the present application;

[0028] Reference numerals:

[0029] Substrate 110 ; anode 120 ; hole transport layer 130 ; light emitting layer 140 ; ​​electron transport layer 150 ; cathode 160 . DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not used to limit the present application.

[0031] The embodiments of the present application provide a composite material and a preparation method thereof, a quantum dot light-emitting diode and a preparation method thereof. These are described in detail below. It should be understood that the order of the following embodiments does not limit the preferred order of the embodiments. In addition, in the description of this application, the term "including" means "including but not limited to". The various embodiments in this application may be in the form of a range. It should be understood that the description in the form of a range is only for convenience and simplicity and should not be understood as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the present application provides an embodiment with a range value of 20-50 mg / mL. It should be considered that the range description of 20-50 mg / mL has specifically disclosed sub-ranges, such as 20-25 mg / mL, 30-35 mg / mL, 40-45 mg / mL, 20-35 mg / mL, 20-45 mg / mL, 40-50 mg / mL, etc., as well as single values ​​within the range, such as 20 mg / mL, 25 mg / mL, 30 mg / mL, 35 mg / mL, 40 mg / mL, 45 mg / mL, 50 mg / mL. In addition, whenever a numerical range is given herein, it is intended to include any citable value (fractional and integer) within the indicated range, and this principle applies regardless of the range.

[0032] To better understand this solution, a composite material is provided herein, comprising quantum dots and MXenes, wherein the metal atoms of the quantum dots are connected to the surface groups of the MXenes via coordination bonds. This composite material can improve the agglomeration phenomenon during the film formation process when preparing the light-emitting layer, thereby providing better photostability. In addition, when a quantum dot light-emitting diode is prepared using the light-emitting layer composite material, wherein the quantum dots are attached to the wrinkled structure of the MXenes, the composite material forms a fluorescence emission channel between the adjacent wrinkled structures of the MXenes nanosheets, so that the fluorescence emitted by the quantum dots can be reflected by the wrinkled walls and emitted outward through the fluorescence emission channel, which can improve the quantum efficiency of the device to a certain extent.

[0033] Among them, "MXenes" is also called two-dimensional transition metal carbides, nitrides or carbonitrides, which is a new type of two-dimensional structural material. Its chemical formula can be expressed as M n+1 X n T z Indicates, where M refers to a transition metal, including Ti, Zr, Hf, V, Nb, Ta, Cr, Sc, etc.; X refers to C and / or N, n is generally 1-3, T z Refers to surface groups, including O 2- OH - 、F - NH 3 NH 4+Preferably, the surface groups of MXenes are one or more of hydroxyl groups and halogen groups. It is understood that MXenes can be surface groups T z is a hydroxyl group or a halogen group and M n+1 and X n Any combination of MXenes, such as Ti3C2(OH)2, Zr3CCl2, Ti3C2F2, Mo2CF2, etc. MXenes with hydroxyl or halogen groups on the surface are more likely to coordinate with the metal atoms in the quantum dot shell. At the same time, electrons are introduced into the light-emitting layer through the electron transport layer. Under the action of the quantum confinement effect of MXenes, the light-emitting layer has good carrier transport capacity. The carriers are transported through the M n+1 X n T z The surface groups of MXenes nanosheets, such as -OH and -F, are transferred to quantum dots, which enhances the luminescence efficiency of the device and improves the performance of quantum dot light-emitting diodes.

[0034] The constituent elements of quantum dots include IV, II-VI, IV-VI or III-V elements, and the quantum dots include core-shell structure quantum dots selected from CdSe, ZnSe, PbSe, CdTe, InP, GaN, GaP, AlP, InN, ZnTe, InAs, GaAs, CaF2, Cd 1-x Zn x S, Cd 1-x Zn x Se, CdSe y S 1-y 、PbSe y S 1-y 、Zn x Cd 1-x Te, CdS / ZnS, Cd 1-x Zn x S / ZnS、Cd 1-x Zn x Se / ZnSe、CdSe 1-x S x / CdSe y S 1-y / CdS、CdSe / Cd 1-x Zn x Se / Cd y Zn 1-y Se / ZnSe、Cd 1-x Zn x Se / Cd y Zn 1-y Se / ZnSe, CdS / Cd 1-x Zn x S / Cd y Zn 1-yS / ZnS, NaYF4, NaCdF4, Cd 1-x Zn x Se y S 1-y 、CdSe / ZnS、Cd 1-x Zn x Se / ZnS, CdSe / CdS / ZnS, CdSe / ZnSe / ZnS, Cd 1-x Zn x Se / Cd y Zn 1-y One or more of S / ZnS, InP / ZnS, where 0≤x≤1, 0≤y≤1, and x and y are not simultaneously 0 and 1, and x and y are fixed values. Quantum dots have excellent optical properties, including continuously tunable luminescence peak positions across the entire spectrum, high color purity, and excellent stability, making them an excellent luminescent and optoelectronic material.

[0035] It should be noted that in some embodiments of the present application, the quantum dots can be blue light quantum dots, red light quantum dots or green light quantum dots. Since blue light quantum dots are used as light-emitting layer materials, they are currently the most commonly used system in quantum dot-based light-emitting systems. At the same time, the preparation method of light-emitting diodes based on blue light quantum dots is relatively difficult. Therefore, blue light quantum dots are more valuable for reference. Blue light quantum dots include CdS / ZnS, Cd 1-x Zn x S, Cd 1-x Zn x S / ZnS.

[0036] Optionally, the quantum dots are core-shell quantum dots, and the metal atoms are shell metal atoms of the core-shell quantum dots. By coating the shell layer, the fluorescence properties of the quantum dots can be effectively improved, the quantum efficiency can be increased, and the photoelectric effect can be enhanced.

[0037] To better understand the present invention, a method for preparing a composite material is provided, comprising:

[0038] Step S110: mixing a first organic solvent in which quantum dots are dispersed with MXenes for reaction;

[0039] Step S120: After solid-liquid separation, a composite material is obtained.

[0040] The mixing reaction in step S110 includes mixing the first organic solvent containing the dispersed quantum dots with the MXenes and stirring the mixture. Stirring allows for a more complete reaction between the quantum dots and the MXenes, thereby increasing the yield of the MXenes-quantum dot composite material. It is understood that stirring can be replaced by other similar operations, such as ultrasound or vortexing. Stirring includes mechanical stirring, magnetic stirring, and the like.

[0041] In step S120, the composite material refers to the solid precipitate after solid-liquid separation, which specifically includes: cooling the solution after the reaction to room temperature, precipitating it with a second organic reagent, or collecting the precipitate by centrifugation or other means; wherein the second organic reagent is selected from one or more of ethyl acetate, acetone, and ethanol. The second organic solvent precipitation is achieved by utilizing the solubility of the second organic solvent in the reactants, and the luminescent layer composite material is precipitated by using a good solvent and a poor solvent, removing the solvent used in the previous stage, etc., to achieve product collection. It is understood that the second organic reagent can be used alone or in combination. In addition, the process of treating with the second organic reagent can be repeated to achieve product purification, for example, first treating with ethyl acetate + ethanol and then treating with acetone + ethanol.

[0042] The molar ratio of quantum dots to MXenes is 1:0.05 to 0.5. It is understood that the molar ratio of quantum dots to MXenes can be any value within the range of 1:0.05 to 0.5, such as 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, and the like. Preferably, the molar ratio of quantum dots to MXenes is 1:0.1 to 0.3. When the molar ratio of quantum dots to MXenes is 1:0.05 to 0.5, the resulting luminescent layer composite material has a sufficient amount of MXenes and quantum dots combined, significantly improving the quantum dot carrier efficiency. Furthermore, the luminescent layer composite material prepared under these conditions has good dispersion in the solvent, and the resulting luminescent layer film is relatively smooth, which is beneficial for improving device performance. When the molar ratio of quantum dots to MXenes is less than 1:0.1, the amount of MXenes and quantum dots combined is low, and the effect of improving the quantum dot carrier efficiency is not significant. When the molar ratio of quantum dots to MXenes is greater than 1:0.3, the dispersion of the prepared MXenes-quantum dots in the solvent is poor, the film roughness is high, and the device performance is affected.

[0043] The first organic solvent is an olefin or alkane with a boiling point of 280 to 400°C. The first organic solvent is an olefin or alkane with a boiling point of 280 to 400°C. The boiling point within this range can avoid volatilization under the reaction conditions. In addition, the quantum dots dissolve well in the olefin or alkane. It is understandable that the first organic solvent can be an olefin or alkane with a boiling point of 280 to 400°C, such as 1-octadecene (ODE), 1-hexadecene, 1-eicosene, etc. Such solvents are inexpensive, highly stable, and have good dispersion properties for quantum dots.

[0044] The concentration of quantum dots in the first organic solvent is 20 to 50 mg / mL. It is understandable that the concentration of quantum dots in the first organic solvent can be any value between 20 and 50 mg / mL, such as 20 mg / mL, 25 mg / mL, 30 mg / mL, 35 mg / mL, 40 mg / mL, 45 mg / mL, 50 mg / mL, etc. Preferably, the concentration of quantum dots in the first organic solvent is 20 to 30 mg / mL. Within this concentration range, quantum dots are not easily agglomerated in the solvent, a better dispersion effect can be obtained, an optimal contact area can be obtained during the ligand exchange reaction, and excessive grafting of ligands is not easily caused. The resulting composite material has good light-emitting layer performance. If the concentration of quantum dots is too low, the dispersion in the solvent will be too large, the spacing between particles will be too large, and excessive grafting of ligands will be caused, which will ultimately affect the performance of the light-emitting layer. If the concentration of quantum dots is too high, agglomerates are easily formed, and a good contact environment with the ligands cannot be formed.

[0045] Preferably, step S110 can be carried out at 200-250°C under protective gas conditions. It is understandable that the temperature can be any value within 200-250°C, such as 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, 250°C, etc. More preferably, the temperature is 200-220°C. This temperature range can achieve sufficient reaction between MXenes and quantum dots. Protective gases include argon (Ar) and nitrogen (N2). Carrying out in a protective gas atmosphere can effectively avoid unwanted reactions such as oxidation, making the reaction product purer.

[0046] It is worth noting that the MXenes used to prepare the composite material can be purchased from existing products or prepared from MAX phase materials. In order to better understand the present invention, a method for preparing MXenes is provided herein, comprising:

[0047] Step S210: soaking the MAX phase material in an active treatment solution at a temperature of 80-100° C. for 7-10 hours;

[0048] Step S220: Filter to obtain MXenes material;

[0049] The active treatment solution is selected from one or more of hydrofluoric acid, a mixture of hydrochloric acid and fluoride, and an alkaline solution. The active treatment solution can be used to extract the weakly bound A-site elements (such as Al atoms) in the MAX phase material to obtain MXenes materials. In addition, the active treatment solution can also provide T z The surface groups such as Ti3C2F2, Zr3C2F2 can be prepared by immersing in hydrofluoric acid active treatment solution. zThe MXenes material with -F is first immersed in a hydrofluoric acid treatment solution and then immersed in an alkaline active treatment solution to obtain surface groups T such as Ti3C2(OH)2 and Zr3C2(OH)2. z MXenes materials with -OH, etc., can be better used in subsequent experiments.

[0050] In step S210, the active treatment solution is at a temperature of 80-100° C., preferably, at a temperature of 95-100° C. It is worth noting that the active treatment solution can be heated to 80-100° C., or an active treatment solution at 80-100° C. can be provided.

[0051] A washing step may also be included between steps S210 and S220: the MXenes sample is washed with deionized water until the pH value of the solution is between 6 and 7.

[0052] After step S220, a drying step may be included: vacuum heating and drying at 95 to 105°C for 20 to 25 hours. It is understandable that vacuum heating and drying can be performed at any value within the range of 95 to 105, such as 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, etc. Under these conditions, the solvent can be fully dried to obtain a dry MXenes material for subsequent experiments. It is worth noting that the temperature can be raised to 95 to 105°C, or a vacuum heating environment of 95 to 105°C can be provided.

[0053] The MAX phase material can be represented by the basic chemical formula M (n+1) AX n where M represents a transition metal element, including Ti, Zr, Hf, V, Nb, Ta, Cr, Sc, etc., A represents a main group element, including Al, Zn, Si, Ga, etc., and X represents carbon or nitrogen. This material can also utilize commercially available MAX phase materials or be prepared. To better understand this solution, a method for preparing a MAX phase material is provided herein, comprising:

[0054] Step S310: mixing the first powder, the second powder and the third powder in a molar ratio of 3:1-2:1-2;

[0055] Step S320: calcining at 650-750°C for 1-2 hours to prepare a MAX phase material, wherein the first powder is metal powder M, selected from one or more of Ti, Zr, Hf, V, Nb, Ta, Cr, and Sc; the second powder is metal powder A, selected from one or more of Al, Zn, Si, and Ga; and the third powder is a carbon source X, such as graphite.

[0056] The molar ratio of the first powder: the second powder: the third powder is 3:1-2:1-2. It is understandable that the ratio of the first powder, the second powder and the third powder can be any value in 3:1-2:1-2, such as 3:1.1:1, 3:1.2:2, 3:1.3:1, 3:1.4:2, 3:1.5:1, 3:1.6:2, 3:1.7:1, 3:1.8:2, 3:1.9:1, 3:2:2, etc. Preferably, the molar ratio of the first powder: the second powder: the third powder is 3:1.2-1.7:1.5-2. Within this ratio range, a fully reacted MAX phase material can be prepared, and impurity compounds are not easily formed, which reduces the difficulty of impurity removal. The MAX phase material prepared in this ratio can have an appropriate amount of metal powder A converted into T in the further preparation process of MXenes. z . The obtained MAX phase material can be used as the raw material for the preparation of subsequent light-emitting layer composite materials, quantum dot light-emitting diodes, etc., which can enable subsequent experiments to achieve better results. For example, the light-emitting layer composite material prepared with this MAX phase material as the raw material can obtain a compact and dense film in the preparation of quantum dot light-emitting diodes, and the particles on the film surface are evenly distributed, which effectively improves the photoelectric performance of the quantum dot light-emitting diode. When the molar ratio of the first powder: the second powder: the third powder is less than 3:1 to 2:1, the carbon source X is insufficient, the metal powder M and the metal powder A are excessive, and the produced MAX phase material is insufficient; when the molar ratio of the first powder: the second powder: the third powder is greater than 3:1 to 2:2, the carbon source X is excessive, and impurity compounds are easily formed, which are not easy to remove. Furthermore, it is a preferred embodiment to control the molar ratio of the first powder: the second powder to be 3:1 to 2, because when the molar ratio of the first powder: the second powder is less than 3:1, the amount of metal powder A in the subsequent reaction is small, resulting in the conversion into T in the process of preparing MXenes through this MAX phase material. z When the molar ratio of the first powder to the second powder is greater than 3:2, the metal powder A in the subsequent preparation of MXenes by this MAX phase material cannot be completely converted into T z , there is metal powder A remaining, which is not easy to remove.

[0057] In step S320, the temperature is calcined at 650-750°C for 1-2 hours. It is understood that the calcination temperature can be any value between 650-750°C, such as 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, etc. Preferably, the temperature is calcined at 650-700°C. When calcined within this range, sintering is not likely to occur and the reaction can be sufficient. It is worth noting that the temperature can be raised to 650-750°C, or a calcination environment of 650-750°C can be provided. Further, the calcination temperature is calcined for 1-2 hours, preferably, for 1-1.5 hours. It is worth noting that this step can be carried out by any equipment in the art that can achieve this condition, such as a tubular furnace. Preferably, the calcination process can be carried out in a protective gas atmosphere, including argon (Ar) and nitrogen (N2). Carrying out the reaction in a protective gas atmosphere can effectively avoid unwanted reactions such as oxidation, making the reaction products purer.

[0058] A ball milling step may be included between step S310 and step S320: ball milling for 45 to 50 hours. The ball milling process may utilize materials commonly used in the art, including one or more of agate, zirconium dioxide, stainless steel, quenched and tempered steel, hard tungsten carbide, silicon nitride, or sintered corundum. The ball milling time may be any number within the range, such as 45 hours, 46 hours, 47 hours, 48 ​​hours, 49 hours, or 50 hours. Within this timeframe, the ball milling process can break up the materials, making the powders of materials M, A, and X more uniform and allowing for more thorough mixing.

[0059] A tabletting step may be included between the ball milling step and step S320: pressing at 0.8-1.2 MPa to obtain a tablet. The tablet shape is not limited, such as a round shape. This step facilitates subsequent experimental operations.

[0060] After step S320 , a grinding step may be further included: grinding the MAX phase material to obtain MAX phase material powder.

[0061] To better understand the present solution, a quantum dot light-emitting diode is provided herein, comprising a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode, wherein the material of the light-emitting layer comprises a composite material;

[0062] Among them, the composite material includes quantum dots and MXenes, and the metal atoms of the quantum dots are connected to the surface groups of MXenes through coordination bonds.

[0063] Preferably, in addition to the above, the quantum dot light-emitting diode further comprises a substrate. There is no clear limitation on the choice of substrate, and a hard glass substrate or a flexible PET substrate can be used to prepare a flexible device.

[0064] The hole transport layer can be made of conventional hole transport materials in the art, such as poly(9,9-dioctylfluorene-co-n-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), polytriphenylamine (Poly-TPD), tris(4-(9-carbazolyl)phenyl)amine (TCTA), 4,4′-N,N′-dicarbazolebiphenyl (CBP), poly(3,4-ethylenedioxythiophene) / polystyrenesulfonate) (PEDOT:PSS), etc., or a mixture of any combination thereof, or other high-performance hole transport materials.

[0065] The light-emitting layer can be made of the above-mentioned composite material MXenes-quantum dots. When a quantum dot light-emitting diode is prepared using the composite material, the wrinkled structure of the MXenes nanosheets can form a fluorescence emission channel. The fluorescence emitted by the quantum dots attached to the MXenes can pass through the fluorescence emission channel and emit outward, which can improve the quantum efficiency of the device to a certain extent. At the same time, electrons are introduced into the light-emitting layer through the electron transport layer. Under the action of the MXenes quantum confinement effect, the light-emitting layer has good carrier transport capacity. The carriers pass through the MXenes. n+1 X n T z The surface groups (-OH, -F) of the MXenes nanosheets are transferred to the quantum dot position, which enhances the luminescence efficiency of the device and improves the performance of quantum dot light-emitting diodes.

[0066] The electron transport layer can be made of conventional electron transport materials in the art, such as zinc oxide (ZnO), calcium (Ca), barium (Ba), cesium fluoride (CsF), lithium fluoride (LiF), cesium carbonate (CsCO3), 8-hydroxyquinoline aluminum (Alq3), etc.

[0067] Quantum dot light-emitting diodes can be positive-type, with the anode positioned close to the substrate. Anode materials can be doped metal oxides, such as 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). Alternatively, they can be composite electrodes composed of metals sandwiched between doped or undoped transparent metal oxides, such as AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, and ZnS / Al / ZnS. Cathode materials can be metals or alloys, such as silver (Ag), aluminum (Al), and gold (Au).

[0068] Quantum dot light-emitting diodes can also have an inversion configuration, where the cathode is positioned close to the substrate. Cathode materials can be doped metal oxides, such as 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). They can also be composite electrodes consisting of a metal sandwiched between doped or undoped transparent metal oxides, such as AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, and ZnS / Al / ZnS. Anode materials can be metals or alloys, such as silver (Ag), aluminum (Al), and gold (Au).

[0069] It is worth noting that, in addition to the above-mentioned layers, the quantum dot light-emitting diode provided in this application may also be provided with some functional layers that help improve the performance of the quantum dot light-emitting diode, including an electron injection layer, a hole injection layer, etc. The materials of each layer of the quantum dot light-emitting diode provided in this application may be conventional materials in the art and are not limited to the range of materials stated in the embodiments.

[0070] Accordingly, to better understand the present invention, a method for preparing a quantum dot light-emitting diode is provided, comprising:

[0071] Step S410: providing a solution of the composite material dissolved in a solvent, wherein the solvent is an alkane-type non-polar solvent;

[0072] Step S420: depositing a solution on the electron transport layer to form a light-emitting layer;

[0073] Alternatively, a solution is deposited on the hole transport layer to form a light-emitting layer;

[0074] The composite material includes quantum dots and MXenes, and the metal atoms of the quantum dots are connected to the surface groups of the MXenes through coordination bonds.

[0075] A solution of the composite material dissolved in a solvent is provided, wherein the non-polar solvent is selected from one or more non-polar solvents such as alkanes, alkenes, and hydrocarbon derivatives, for example, one or more of n-hexane, n-octane, n-decane, chloroform, and ODE. Preferably, the solvent is an alkane non-polar solvent. The composite material can be well dispersed in the alkane non-polar solvent and can be used for storage and subsequent operations.

[0076] In step S420, the deposition solution includes placing a substrate coated with a hole transport layer or an electron transport layer on a coating machine, spin-coating a composite material solution of a certain concentration into a film, and drying at an appropriate temperature. The thickness of the light-emitting layer is controlled by adjusting the concentration of the solution, the spin coating speed, and the spin coating time. The thickness of the light-emitting layer is about 20 to 60 nm. It is understood that the thickness of the light-emitting layer can be any value within 20 to 60 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, etc. Within the thickness of this light-emitting layer, agglomeration and hole defects are not easy to occur, and the prepared quantum dot light-emitting diode has better performance. It is understandable that the method for preparing the light-emitting layer in this application can be achieved by other methods with the same or similar effects in addition to spin coating, including solution processing, such as spraying, scraping, etc. to deposit the composite material onto the hole transport layer or the electron transport layer.

[0077] It is worth noting that the preparation methods of each layer in the quantum dot light-emitting diode can be achieved by conventional techniques in the field. Deposition includes chemical and physical methods, among which chemical methods include: chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods include physical plating and solution processing. Specific physical plating methods include: thermal evaporation, electron beam evaporation, magnetron sputtering, multi-arc ion plating, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc. Solution processing methods include spin coating, printing, inkjet printing, doctor blade coating, printing, dip-coating, immersion, spraying, roller coating, casting, slit coating, and strip coating. The specific processing methods and processing conditions are all common methods in the field.

[0078] The preparation method of a quantum dot light-emitting diode with a positive configuration may further include step S411 between step S410 and step S420: depositing a hole transport layer on an ITO substrate. Specifically, the ITO substrate may be placed on a coating machine, and a solution of the prepared hole transport material may be spin-coated to form a film; the film thickness may be controlled by adjusting the concentration of the solution, the spin-coating speed, and the spin-coating time, and then thermally annealing may be performed at an appropriate temperature. After step S420, step S431 may be included: depositing an electron transport layer on the light-emitting layer. The electron transport layer may be deposited by placing the substrate on which the light-emitting layer has been spin-coated in a vacuum evaporation chamber, and evaporating a layer of electron transport layer with a thickness of about 80 nm at an evaporation speed of about 0.01 to 0.5 nm / s. After step S431, step S441 may be included: depositing a cathode on the electron transport layer. The cathode can be deposited by placing the substrate after depositing each functional layer in a vapor deposition chamber and thermally evaporating a layer of 15-30nm metal silver or aluminum as the cathode through a mask plate, or using nano-Ag wires or Cu wires, which have a smaller resistance so that carriers can be injected smoothly.

[0079] The method for preparing a quantum dot light-emitting diode with an inverted configuration may further include step S412 between step S410 and step S420: depositing an electron transport layer on an ITO substrate. The electron transport layer may be deposited by placing the ITO substrate in a vacuum evaporation chamber and evaporating a layer of electron transport layer with a thickness of about 80 nm at an evaporation rate of about 0.01 to 0.5 nm / s. After step S420, step S432 may be included: depositing a hole transport layer on the light-emitting layer. The hole transport layer may be deposited by placing the substrate coated with the light-emitting layer on a coating machine and spin-coating a solution of the prepared hole transport material into a film; the film thickness may be controlled by adjusting the concentration of the solution, the spin-coating speed and the spin-coating time, and then thermally annealing at an appropriate temperature. After step S432, step S442 may be included: depositing an anode on the hole transport layer. Among them, the anode can be deposited by placing the substrate with each functional layer deposited in a vapor deposition chamber and thermally evaporating a layer of 15-30nm metal silver or aluminum as the anode through a mask plate, or using nano-Ag wire or Cu wire, which has a smaller resistance so that carriers can be injected smoothly.

[0080] After step S441 or step S442, step S450 may be included: packaging the quantum dot light-emitting diode. This packaging can be performed using a conventional machine or manually. Preferably, packaging is performed in an environment where both oxygen and water contents are less than 0.1 ppm to ensure device stability.

[0081] In order to better understand the present solution, specific examples 1-12 and comparative examples 1-3 are provided here to further illustrate the present solution in detail.

[0082] Example 1

[0083] This embodiment provides a method for preparing a composite material, comprising the following steps:

[0084] (1) Titanium (Ti) powder, aluminum (Al) powder, and graphite were mixed in a molar ratio of 3:1.5:2; after 48 hours of ball milling, they were pressed into small discs under a high pressure of 1 MPa; the small discs were placed in a tube furnace, purged with argon (Ar), and calcined at 700°C for 1 hour; the small discs were removed, cooled to room temperature, and ground into powder for use, thereby obtaining the MAX phase material Ti3AlC2;

[0085] (2) Ti3AlC2 was immersed in hydrofluoric acid at a temperature of 100°C for 10 hours to peel off the Al layer and achieve fluorination treatment; after fluorination activation treatment, MXenes were washed with deionized water until the pH value of the solution was between 6 and 7; finally, the MXenes solution was filtered and dried under vacuum at 100°C for 24 hours to prepare the MXenes material Ti3C2F2. The chemical reaction formulas involved are: Ti3AlC2+3HF=AlF3+3 / 2H2+Ti3C2, Ti3C2+2HF=Ti3C2F2+H2;

[0086] (3) At 200°C and in an argon atmosphere, CdS / ZnS was dispersed in 20 mL of 1-octadecene (ODE) and mixed with Ti3C2F2 material for 30 min, wherein the concentration of CdS / ZnS in 1-octadecene (ODE) was 20 mg / mL, and the molar ratio of CdS / ZnS to Ti3C2F2 was 1:0.1. After the reaction was completed and the reaction solution cooled to room temperature, 10 mL of the original solution was taken and precipitated with 20 mL of ethyl acetate + 10 mL of ethanol for the first time, centrifuged and dissolved in n-hexane. A second precipitation was performed with 10 mL of acetone + 10 mL of ethanol, and the composite material Ti3C2F2-CdS / ZnS was obtained after centrifugation. The composite material was then redispersed in n-hexane to obtain a Ti3C2F2-CdS / ZnS composite material solution.

[0087] Example 2

[0088] This embodiment provides a method for preparing a composite material, comprising the following steps:

[0089] (1) Ti powder, Al powder, and graphite were mixed in a molar ratio of 3:1.3:2; after ball milling for 48 hours, the mixture was pressed into small discs under a high pressure of 1 MPa; the small discs were placed in a tube furnace, introduced with Ar gas, and calcined at 650°C for 1.5 hours; the small discs were taken out, cooled to room temperature, and then ground into powder for use, thereby obtaining Ti3AlC2 material;

[0090] (2) The Ti3AlC2 material was immersed in hydrofluoric acid at a temperature of 100°C for 5 hours, the Al layer was peeled off, and then alkalized with 5% NaOH for 2 hours to obtain MXenes rich in OH groups, thereby achieving alkaline activation treatment; after the alkaline activation treatment, the MXenes were washed with deionized water until the pH value of the solution was between 6 and 7; finally, the MXenes solution was filtered and dried under vacuum at 100°C for 24 hours to prepare Ti3C2(OH)2 material. The chemical reaction formulas involved are: Ti3AlC2+3HF=AlF3+3 / 2H2+Ti3C2, Ti3C2+2HF=Ti3C2F2+H2, Ti3C2F2+2NaOH=Ti3C2(OH)2+2NaF;

[0091] (3) At 200℃, in an argon atmosphere, Cd 1-x Zn x S was dispersed in 20 mL of 1-hexadecene and mixed with Ti3C2(OH)2 material and stirred for 1 h. 1-x Zn x The concentration of S in 1-hexadecene was 30 mg / mL, and Cd 1-x Zn x The molar ratio of S to Ti3C2(OH)2 is 1:0.2. After the reaction is completed and the reaction solution is cooled to room temperature, 10 mL of the original solution is taken and precipitated with 20 mL of ethyl acetate + 10 mL of ethanol for the first time. After centrifugation, it is dissolved in n-hexane. The second precipitation is carried out with 10 mL of acetone + 10 mL of ethanol. After centrifugation, the composite material Ti3C2(OH)2-Cd 1-x Z nx S; then redispersed in n-octane to obtain the composite material Ti3C2(OH)2-Cd 1- x Z nx S solution.

[0092] Example 3

[0093] This embodiment provides a method for preparing a composite material, comprising the following steps:

[0094] (1) Zirconium (Zr) powder, Al powder, and graphite were mixed in a molar ratio of 3:1.2:2; after ball milling for 48 hours, the mixture was pressed into small discs under a high pressure of 1 MPa; the small discs were placed in a tube furnace, introduced with Ar gas, and calcined at 700°C for 1 hour; the small discs were taken out and ground into powder after cooling to room temperature, thereby obtaining Zr3AlC2 material;

[0095] (2) The Zr3AlC2 material was immersed in hydrofluoric acid at a temperature of 100°C for 10 hours to peel off the Al layer and achieve fluorination treatment; after the fluorination activation treatment, the MXenes sample was washed with deionized water until the pH value of the solution was between 6 and 7; finally, the MXenes solution was filtered and dried under vacuum at 100°C for 24 hours to prepare the Zr3C2F2 material. The chemical reaction formulas involved are: Zr3AlC2+3HF=AlF3+3 / 2H2+Zr3C2, Zr3C2+2HF=Zr3C2F2+H2;

[0096] (3) At 200℃, in an argon atmosphere, Cd 1-x Zn x S / ZnS was dispersed in 20 mL of ODE and mixed with Zr3C2F2 material and stirred for 30 min. 1-x Znx The concentration of S / ZnS in ODE was 20 mg / mL, and Cd 1-x Zn x The molar ratio of S / ZnS to Zr3C2F2 is 1:0.3. After the reaction is completed and the reaction solution is cooled to room temperature, 10 mL of the original solution is taken and precipitated with 20 mL of ethyl acetate + 10 mL of ethanol for the first time. After centrifugation, it is dissolved in n-hexane. The second precipitation is carried out with 10 mL of acetone + 10 mL of ethanol. After centrifugation, the composite material Zr3C2F2-Cd 1-x Zn x S / ZnS; then redispersed in n-hexane to obtain the composite material Zr3C2F2-Cd 1-x Zn x S / ZnS solution.

[0097] Example 4

[0098] This embodiment provides a method for preparing a composite material, comprising the following steps:

[0099] (1) Titanium (Ti) powder, aluminum (Al) powder, and graphite were mixed in a molar ratio of 3:1.5:1.2; after 48 hours of ball milling, the mixture was pressed into small discs under a high pressure of 1 MPa; the small discs were placed in a tube furnace, purged with argon (Ar), and calcined at 750°C for 1 hour; the small discs were removed, cooled to room temperature, and then ground into powder for use, thereby obtaining the MAX phase material Ti3AlC2;

[0100] (2) Ti3AlC2 was immersed in hydrofluoric acid at a temperature of 100°C for 10 hours to peel off the Al layer and achieve fluorination treatment; after fluorination activation treatment, MXenes were washed with deionized water until the pH value of the solution was between 6 and 7; finally, the MXenes solution was filtered and dried under vacuum at 100°C for 24 hours to prepare the MXenes material Ti3C2F2. The chemical reaction formulas involved are: Ti3AlC2+3HF=AlF3+3 / 2H2+Ti3C2, Ti3C2+2HF=Ti3C2F2+H2;

[0101] (3) At 200°C and in a nitrogen atmosphere, CdS / ZnS was dispersed in 20 mL of 1-octadecene (ODE) and mixed with Ti3C2F2 material for 30 min. The concentration of CdS / ZnS in 1-octadecene (ODE) was 48 mg / mL, and the molar ratio of CdS / ZnS to Ti3C2F2 was 1:0.1. After the reaction was completed and the reaction solution cooled to room temperature, 10 mL of the original solution was taken and precipitated with 20 mL of ethyl acetate + 10 mL of ethanol for the first time. After centrifugation, it was dissolved in n-hexane. The second precipitation was carried out with 10 mL of acetone + 10 mL of ethanol. After centrifugation, the composite material Ti3C2F2-CdS / ZnS was obtained. The composite material Ti3C2F2-CdS / ZnS was then redispersed in chloroform to obtain a composite material Ti3C2F2-CdS / ZnS solution.

[0102] Example 5

[0103] This embodiment provides a method for preparing a composite material, comprising the following steps:

[0104] (1) Ti powder, Al powder, and graphite were mixed in a molar ratio of 3:1.3:2; after ball milling for 48 hours, the mixture was pressed into small discs under a high pressure of 1 MPa; the small discs were placed in a tube furnace, introduced with Ar gas, and calcined at 650°C for 1.5 hours; the small discs were taken out, cooled to room temperature, and then ground into powder for use, thereby obtaining Ti3AlC2 material;

[0105] (2) The Ti3AlC2 material was immersed in hydrofluoric acid at a temperature of 80°C for 5 hours, the Al layer was peeled off, and then alkalized with 5% NaOH for 2 hours to obtain MXenes rich in OH groups, thereby achieving alkaline activation treatment; after the alkaline activation treatment, the MXenes were washed with deionized water until the pH value of the solution was between 6 and 7; finally, the MXenes solution was filtered and dried under vacuum at 100°C for 24 hours to prepare Ti3C2(OH)2 material. The chemical reaction formulas involved are: Ti3AlC2+3HF=AlF3+3 / 2H2+Ti3C2, Ti3C2+2HF=Ti3C2F2+H2, Ti3C2F2+2NaOH=Ti3C2(OH)2+2NaF;

[0106] (3) Cd 1-x Zn x S was dispersed in 20 mL of 1-eicosene and mixed with Ti3C2(OH)2 material and stirred for 1 h, wherein Cd 1-x Zn x The concentration of S in 1-eicosene was 30 mg / mL, and Cd 1-x Zn xThe molar ratio of S to Ti3C2(OH)2 is 1:0.05. After the reaction is completed and the reaction solution is cooled to room temperature, 10 mL of the original solution is taken and precipitated with 20 mL of ethyl acetate + 10 mL of ethanol for the first time. After centrifugation, it is dissolved in n-hexane. The second precipitation is carried out with 10 mL of acetone + 10 mL of ethanol. After centrifugation, the composite material Ti3C2(OH)2-Cd 1-x Z nx S; then redispersed in n-octane to obtain the composite material Ti3C2(OH)2-Cd 1- x Z nx S solution.

[0107] Example 6

[0108] This embodiment provides a method for preparing a composite material, comprising the following steps:

[0109] (1) Zirconium (Zr) powder, Al powder, and graphite were mixed in a molar ratio of 3:2:2; after ball milling for 48 hours, the mixture was pressed into small discs under a high pressure of 1 MPa; the small discs were placed in a tube furnace, introduced with Ar gas, and calcined at 700°C for 1 hour; the small discs were removed, cooled to room temperature, and then ground into powder for use, thereby obtaining Zr3AlC2 material;

[0110] (2) The Zr3AlC2 material was immersed in hydrofluoric acid at a temperature of 100°C for 10 hours to peel off the Al layer and achieve fluorination treatment; after the fluorination activation treatment, the MXenes sample was washed with deionized water until the pH value of the solution was between 6 and 7; finally, the MXenes solution was filtered and dried under vacuum at 100°C for 24 hours to prepare the Zr3C2F2 material. The chemical reaction formulas involved are: Zr3AlC2+3HF=AlF3+3 / 2H2+Zr3C2, Zr3C2+2HF=Zr3C2F2+H2;

[0111] (3) At 200℃, in nitrogen atmosphere, Cd 1-x Zn x S / ZnS was dispersed in 20 mL of ODE and mixed with Zr3C2F2 material and stirred for 30 min. 1-x Zn x The concentration of S / ZnS in ODE was 35 mg / mL, and Cd 1-x Zn x The molar ratio of S / ZnS to Zr3C2F2 is 1:0.5. After the reaction is completed and the reaction solution is cooled to room temperature, 10 mL of the original solution is taken and precipitated with 20 mL of ethyl acetate + 10 mL of ethanol for the first time. After centrifugation, it is dissolved in n-hexane. The second precipitation is carried out with 10 mL of acetone + 10 mL of ethanol. After centrifugation, the composite material Zr3C2F2-Cd1-x Zn x S / ZnS; then redispersed in ODE to obtain the composite material Zr3C2F2-Cd 1-x Zn x S / ZnS solution.

[0112] Example 7

[0113] like Figure 1 As shown, this embodiment provides a quantum dot light-emitting diode with a positive configuration, including a stacked substrate 110, an anode 120, a hole transport layer 130, a light-emitting layer 140, an electron transport layer 150 and a cathode 160, wherein the material of the substrate 110 is a glass sheet, the material of the anode 120 is an ITO substrate, the material of the hole transport layer 130 is TFB, the material of the electron transport layer 150 is ZnO, the material of the light-emitting layer 140 is a composite material Ti3C2F2-CdS / ZnS, and the material of the cathode 160 is Al.

[0114] This embodiment also provides a method for preparing a positive-type quantum dot light-emitting diode, comprising the following steps:

[0115] Providing composite material Ti3C2F2-CdS / ZnS solution;

[0116] depositing a hole transport layer on the ITO substrate;

[0117] Depositing Ti3C2F2-CdS / ZnS solution on the hole transport layer to form a light-emitting layer;

[0118] depositing an electron transport layer on the light-emitting layer;

[0119] A cathode is deposited on the electron transport layer to obtain a quantum dot light-emitting diode.

[0120] Example 8

[0121] This embodiment provides a quantum dot light-emitting diode, comprising a stacked substrate, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode, wherein the substrate is made of a glass sheet, the anode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, and the light-emitting layer is made of a composite material Ti3C2(OH)2-Cd 1-x Zn x S, the material of the cathode is Al.

[0122] This embodiment also provides a method for preparing a quantum dot light-emitting diode, comprising the following steps:

[0123] Provide composite material Ti3C2(OH)2-Cd 1-x Zn x S solution;

[0124] depositing a hole transport layer on the ITO substrate;

[0125] Ti3C2(OH)2-Cd was deposited on the hole transport layer. 1-x Zn x S solution, forming a light-emitting layer;

[0126] depositing an electron transport layer on the light-emitting layer;

[0127] A cathode is deposited on the electron transport layer to obtain a quantum dot light-emitting diode.

[0128] Example 9

[0129] This embodiment provides a quantum dot light-emitting diode, comprising a stacked substrate, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode, wherein the substrate is made of a glass sheet, the anode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, and the light-emitting layer is made of a composite material Zr3C2F2-Cd 1-x Zn x S / ZnS, the cathode material is Al.

[0130] This embodiment also provides a method for preparing a quantum dot light-emitting diode, comprising the following steps:

[0131] Provide composite material Zr3C2F2-Cd 1-x Zn x S / ZnS solution;

[0132] depositing a hole transport layer on the ITO substrate;

[0133] Deposition of Zr3C2F2-Cd on the hole transport layer 1-x Zn x S / ZnS solution to form the light-emitting layer;

[0134] depositing an electron transport layer on the light-emitting layer;

[0135] A cathode is deposited on the electron transport layer to obtain a quantum dot light-emitting diode.

[0136] Example 10

[0137] like Figure 2As shown, this embodiment provides an inverted quantum dot light-emitting diode, including a stacked anode 120, a hole transport layer 130, a light-emitting layer 140, an electron transport layer 150, a cathode 160 and a substrate 110, wherein the material of the substrate 110 is a glass sheet, the material of the cathode 160 is an ITO substrate, the material of the hole transport layer 130 is TFB, the material of the electron transport layer 150 is ZnO, the material of the light-emitting layer 140 is a composite material Ti3C2F2-CdS / ZnS, and the material of the anode is Al.

[0138] This embodiment also provides a method for preparing a quantum dot light-emitting diode, comprising the following steps:

[0139] Providing composite material Ti3C2F2-CdS / ZnS solution;

[0140] depositing an electron transport layer on an ITO substrate;

[0141] Depositing Ti3C2F2-CdS / ZnS solution on the electron transport layer to form a light-emitting layer;

[0142] depositing a hole transport layer on the light-emitting layer;

[0143] An anode is deposited on the hole transport layer to obtain a quantum dot light-emitting diode.

[0144] Example 11

[0145] This embodiment provides a quantum dot light-emitting diode, comprising a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a substrate, wherein the substrate is made of a glass sheet, the cathode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, and the light-emitting layer is made of a composite material Ti3C2(OH)2-Cd 1-x Zn x S, the material of the anode is Al.

[0146] This embodiment also provides a method for preparing a quantum dot light-emitting diode, comprising the following steps:

[0147] Provide composite material Ti3C2(OH)2-Cd 1-x Zn x S solution;

[0148] depositing an electron transport layer on an ITO substrate;

[0149] Deposition of Ti3C2(OH)2-Cd on the electron transport layer 1-x Zn x S solution, forming a light-emitting layer;

[0150] depositing a hole transport layer on the light-emitting layer;

[0151] An anode is deposited on the hole transport layer to obtain a quantum dot light-emitting diode.

[0152] Example 12

[0153] This embodiment provides a quantum dot light-emitting diode, comprising a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode, and a substrate, wherein the substrate is made of a glass sheet, the cathode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, and the light-emitting layer is made of a composite material Zr3C2F2-Cd 1-x Zn x S / ZnS, the anode material is Al.

[0154] This embodiment also provides a method for preparing a quantum dot light-emitting diode, comprising the following steps:

[0155] Provide composite material Zr3C2F2-Cd 1-x Zn x S / ZnS solution;

[0156] depositing an electron transport layer on an ITO substrate;

[0157] Deposition of Zr3C2F2-Cd on the electron transport layer 1-x Zn x S / ZnS solution to form the light-emitting layer;

[0158] depositing a hole transport layer on the light-emitting layer;

[0159] An anode is deposited on the hole transport layer to obtain a quantum dot light-emitting diode.

[0160] Comparative Example 1

[0161] A quantum dot light-emitting diode comprises a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode and a substrate, wherein the substrate is made of a glass sheet, the cathode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, the light-emitting layer is made of CdS / ZnS quantum dots, and the anode is made of Al.

[0162] Comparative Example 2

[0163] A quantum dot light-emitting diode comprises a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode and a substrate, wherein the substrate is made of a glass sheet, the cathode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, and the light-emitting layer is made of Cd 1-x Zn x S quantum dots, the anode material is Al.

[0164] Comparative Example 3

[0165] A quantum dot light-emitting diode comprises a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer, a cathode and a substrate, wherein the substrate is made of a glass sheet, the cathode is made of an ITO substrate, the hole transport layer is made of TFB, the electron transport layer is made of ZnO, and the light-emitting layer is made of Cd 1-x Zn x S / ZnS quantum dots, the anode material is Al.

[0166] To illustrate the performance changes brought about by the quantum dot light-emitting diodes prepared using the composite material MXenes-quantum dots in the examples of this application, the external quantum efficiency (EQE) of Examples 7-12 and Comparative Examples 1-3 was examined, respectively. The EQE optical test instrument was used to measure the external quantum efficiency of quantum dot light-emitting diodes, namely: anode / hole transport layer / luminescent layer / electron transport layer / cathode, or cathode / electron transport layer / luminescent layer / hole transport layer / anode. The test results are shown in Table 1 below:

[0167] Table 1

[0168]

[0169]

[0170] As can be seen from Table 1 above, the external quantum efficiency of the quantum dot light-emitting diodes (the light-emitting layer material is the composite material MXenes-quantum dots) provided in Examples 7-12 of the present invention is significantly higher than the external quantum efficiency of the quantum dot light-emitting diodes (the light-emitting layer material is quantum dots) in Comparative Examples 1-3, indicating that the quantum dot light-emitting diodes prepared using the composite material MXenes-quantum dots as the light-emitting layer material have better luminous efficiency.

[0171] In summary, the preparation method of a composite material provided in the embodiment of the present application can effectively prepare MXenes-quantum dots. The quantum dots in the composite material are attached to the two-dimensional MXenes nanosheets. When the light-emitting layer is prepared by this composite material, the agglomeration phenomenon in the film forming process can be improved, so that it has better light stability. In addition, when a quantum dot light-emitting diode is prepared using a light-emitting layer composite material, after the quantum dots are attached to the wrinkled structure of MXenes, the composite material forms a fluorescence emission channel between the adjacent wrinkled structures of the MXenes nanosheets, so that the fluorescence emitted by the quantum dots can be reflected by the wrinkled wall and emitted outward through the fluorescence emission channel, which can improve the quantum efficiency of the device to a certain extent. At the same time, electrons are introduced into the light-emitting layer through the electron transport layer. Under the action of the MXenes quantum confinement effect, the light-emitting layer has good carrier transport capacity, and the carriers pass through the M n+1 Xn T z The surface groups (-OH, -F) of the MXene nanosheets are transferred to the quantum dots, enhancing the luminescence efficiency of the device and improving the performance of the quantum dot light-emitting diode. Furthermore, the method of this embodiment is simple to operate, low-cost, and highly reproducible, and has broad application prospects in the field of optoelectronic displays.

[0172] The above is a detailed introduction to a composite material and its preparation method, a quantum dot light-emitting diode and its preparation method provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A composite material, characterized in that The invention comprises quantum dots and MXenes, wherein the metal atoms of the quantum dots are connected to the surface groups of the MXenes through coordination bonds, and the surface groups of the MXenes are one or more of hydroxyl groups and halogen groups; The quantum dots are selected from one or more of CdSe, ZnSe, PbSe, CdTe, InP, GaN, GaP, AlP, InN, ZnTe, InAs, GaAs, CaF2, Cd 1-x Zn x S, Cd 1-x Zn x Se, CdSe y S 1-y , PbSe y S 1-y , Zn x Cd 1-x Te, CdS / ZnS, Cd 1-x Zn x S / ZnS, Cd 1-x Zn x Se / ZnSe, CdSe 1-x S x / CdSe y S 1-y / CdS, CdSe / Cd 1-x Zn x Se / Cd y Zn 1-y Se / ZnSe, Cd 1-x Zn x Se / Cd y Zn 1-y Se / ZnSe, CdS / Cd 1-x Zn x S / Cd y Zn 1-y S / ZnS, NaYF4, NaCdF4, Cd 1-x Zn x Se y S 1-y , CdSe / ZnS, Cd 1-x Zn x Se / ZnS, CdSe / CdS / ZnS, CdSe / ZnSe / ZnS, Cd 1-x Zn x Se / Cd y Zn 1-y S / ZnS, InP / ZnS; The preparation method of the composite material comprises: mixing and reacting a first organic solvent in which the quantum dots are dispersed with the MXenes; The preparation method of the MXenes comprises: immersing the MAX phase material in an active treatment solution at a temperature of 80 to 100° C.; wherein the active treatment solution is selected from one or more of hydrofluoric acid, a mixture of hydrochloric acid and fluoride, and an alkaline solution.

2. The composite material according to claim 1, wherein The quantum dots are core-shell structured quantum dots, and the metal atoms are shell metal atoms of the core-shell structured quantum dots.

3. A method for preparing a composite material, characterized in that: The following steps are involved: mixing a first organic solvent in which quantum dots are dispersed with MXenes for reaction; After solid-liquid separation, a composite material is obtained; the composite material includes quantum dots and MXenes, the metal atoms of the quantum dots are connected to the surface groups of the MXenes through coordination bonds, and the surface groups of the MXenes are one or more of hydroxyl groups and halogen groups; The preparation method of the MXenes comprises: immersing the MAX phase material in an active treatment solution at a temperature of 80 to 100° C.; The active treatment solution is selected from one or more of hydrofluoric acid, a mixture of hydrochloric acid and fluoride, and alkaline solution.

4. The method for preparing a composite material according to claim 3, wherein: The molar ratio of the quantum dots to the MXenes is 1:0.05~0.

5.

5. The method for preparing a composite material according to claim 3, wherein: The first organic solvent is an olefin or alkane with a boiling point of 280-400°C.

6. The method for preparing a composite material according to claim 3, wherein: The mixed reaction is carried out at 200-250° C. under protective gas conditions.

7. A quantum dot light emitting diode, characterized in that: The invention comprises a stacked anode, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode, wherein the material of the light-emitting layer comprises the composite material according to any one of claims 1 to 2; The composite material includes quantum dots and MXenes, the metal atoms of the quantum dots are connected to the surface groups of the MXenes through coordination bonds, and the surface groups of the MXenes are one or more of hydroxyl groups and halogen groups.

8. A method for preparing a quantum dot light-emitting diode, characterized in that: The following steps are involved: Providing a solution of the composite material dissolved in a solvent, wherein the solvent is an alkane-type non-polar solvent; depositing the solution on the electron transport layer to form a light-emitting layer; Alternatively, the solution is deposited on the hole transport layer to form a light-emitting layer; The composite material comprises quantum dots and MXenes, the metal atoms of the quantum dots are connected to the surface groups of the MXenes through coordination bonds, and the surface groups of the MXenes are one or more of hydroxyl groups and halogen groups; The preparation method of the composite material comprises: mixing and reacting a first organic solvent in which the quantum dots are dispersed with the MXenes; The preparation method of the MXenes comprises: immersing the MAX phase material in an active treatment solution at a temperature of 80 to 100° C.; wherein the active treatment solution is selected from one or more of hydrofluoric acid, a mixture of hydrochloric acid and fluoride, and an alkaline solution.

Images