A composite material, a method for preparing the same, a thin film, an optoelectronic device, and a display device

Abstract

This application belongs to the field of display technology and relates to a composite material comprising a quantum rod, a first ligand, and a second ligand, wherein the first and second ligands are connected to the surface of the quantum rod; wherein both the first and second ligands are hydrophobic, the first ligand is oleophilic, and the second ligand is oleophobic. This application also relates to a method for preparing the composite material, a thin film, an optoelectronic device, and a display device. The technical solution provided by this application can improve the uniformity of the composite material arrangement, thereby improving the light extraction efficiency of the optoelectronic device.

Description

Technical Field

[0001] This application relates to the field of display technology, and more specifically, to a composite material and its preparation method, a thin film, an optoelectronic device, and a display apparatus. Background Technology

[0002] As zero-dimensional nanocrystals, quantum dot materials have essentially the same optical and electrical properties in all directions. Therefore, when the quantum dot light-emitting layer is electro-excited, it will form emitted light that is uniformly distributed in all directions.

[0003] To further improve the luminous efficiency of optoelectronic devices, quantum rod materials can be used to replace conventional quantum dot materials. In addition to having quantum confinement effects and narrow emission peaks similar to quantum dots, quantum rods also have anisotropic light absorption and emission characteristics. However, the existing quantum rod materials have poor uniformity of arrangement when forming films, and cannot form a concentrated excitation light direction. Summary of the Invention

[0004] This application provides a composite material, a method for preparing the composite material, a thin film, an optoelectronic device, and a display device.

[0005] This application provides a composite material that employs the following technical solution:

[0006] A composite material includes a quantum rod, a first ligand, and a second ligand, wherein the first ligand and the second ligand are attached to the surface of the quantum rod;

[0007] Both the first ligand and the second ligand are hydrophobic, and the first ligand is oleophilic while the second ligand is oleophobic.

[0008] This application also provides a method for preparing a composite material, which adopts the following technical solution:

[0009] A method for preparing a composite material includes the following steps:

[0010] A quantum rod, a first ligand, and a first solvent are provided and mixed to undergo a first reaction treatment to obtain a nanomaterial, wherein the nanomaterial includes the quantum rod with the first ligand attached to its surface;

[0011] A second ligand is provided, and the second ligand, nanomaterials and a second solvent are mixed to undergo a second reaction treatment to obtain the composite material, wherein the composite material includes the quantum rods with the first ligand and the second ligand connected to their surfaces;

[0012] Both the first ligand and the second ligand are hydrophobic, and the first ligand is oleophilic while the second ligand is oleophobic.

[0013] This application also provides a thin film, which adopts the technical solution described below:

[0014] A thin film, wherein the material of the thin film is selected from the composite material as described above or the composite material obtained by the preparation method as described above;

[0015] The length direction of the quantum rod is parallel to the extension direction of the thin film, and multiple quantum rods are arranged in parallel.

[0016] This application also provides an optoelectronic device, which adopts the technical solution described below:

[0017] An optoelectronic device includes an anode layer, a light-emitting layer, and a cathode layer stacked together, wherein the light-emitting layer comprises a composite material as described above, or comprises a thin film as described above.

[0018] This application also provides a display device that adopts the following technical solution:

[0019] A display device comprising the optoelectronic device described above.

[0020] Compared with the prior art, the embodiments of this application have the following main advantages:

[0021] The composite material provided in this application embodiment has an oleophilic first ligand and an oleophobic second ligand on the quantum rod. The oleophilicity of the first ligand and the oleophobicity of the second ligand are used to adjust the arrangement of the quantum rod, thereby improving the uniformity of the arrangement and effectively improving the light extraction efficiency of the optoelectronic device. Attached Figure Description

[0022] To more clearly illustrate the solution of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the composite material according to an embodiment of this application;

[0024] Figure 2 This is a flowchart of a method for preparing composite materials according to an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the structure of the thin film according to an embodiment of this application;

[0026] Figure 4 This is a schematic diagram of the structure of the optoelectronic device according to an embodiment of this application.

[0027] Reference numerals: 1. Quantum rod; 2. First ligand; 3. Second ligand; 100. Anode layer; 200. Hole functional layer; 201. Hole injection layer; 202. Hole transport layer; 300. Light emitting layer; 400. Electron functional layer; 500. Cathode layer. Detailed Implementation

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0029] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0030] Self-emissive QLED devices using inorganic quantum dots as electroluminescent materials have attracted widespread attention from academia and industry due to their advantages such as wide color gamut coverage, high color purity, ultra-thin and lightweight design, and flexibility. Since quantum dots are 0-dimensional nanocrystals, their optical and electrical properties are essentially consistent in all directions. Therefore, under electroexcitation, the quantum dot emitting layer will emit light uniformly distributed in all directions. When the quantum dot emitting layer emits light perpendicular to the substrate, there is a high probability of light emission. However, as the angle between the quantum dot emitting layer and the substrate increases, the probability of light extraction gradually decreases.

[0031] For bottom-emission quantum dot electroluminescent devices (QLEDs), the external coupling efficiency is typically between 20% and 25%, meaning that without additional light extraction processes, the upper limit of the device's EQE is 25%. Therefore, improving the external coupling efficiency of light extraction is an important way to improve the device's luminous efficiency.

[0032] The poor uniformity of quantum rod material arrangement during film formation makes it impossible to form a concentrated excitation light direction, which leads to an inability to effectively improve the light extraction efficiency of optoelectronic devices. Therefore, how to effectively improve the uniformity of quantum rod material arrangement during film formation has become the main problem to be solved.

[0033] Based on the background technology described above, embodiments of this application provide a composite material.

[0034] Please see Figure 1 As shown, this application provides a composite material including a quantum rod 1, a first ligand 2 and a second ligand 3. In this embodiment, the first ligand 2 and the second ligand 3 are connected to the surface of the quantum rod 1.

[0035] In some embodiments, both the first ligand and the second ligand are hydrophobic, and the first ligand is oleophilic and the second ligand is oleophobic.

[0036] It is understandable that "hydrophilicity" and "hydrophobicity" refer to the affinity for water; "hydrophilicity" indicates that when water is placed on a material surface, the contact angle θ < 90°, and "hydrophobicity" indicates that when water is placed on a material surface, the contact angle θ > 90°. Similarly, "oleophilicity" and "oleophobicity" refer to the affinity for oily substances (such as oily solvents and aliphatic compounds); "oleophilicity" indicates that when oily substances are placed on a material surface, the contact angle θ < 90°, and "oleophobicity" indicates that when oily substances are placed on a material surface, the contact angle θ > 90°.

[0037] The composite material provided in this application improves the uniformity of the composite material arrangement during the film formation process by setting an oleophilic first ligand and an oleophobic second ligand on the quantum rod 1.

[0038] In some embodiments, the first ligand 2 includes a structure as shown in LR; wherein L is C 10 ~C 20 Alkyl group, where R is the first polar group.

[0039] In this embodiment, the first ligand 2 is connected to the quantum rod through the first polar group.

[0040] In this embodiment, the first polar group has metal coordination ability. Optionally, the first polar group is selected from at least one of phosphonic acid group, carboxyl group, mercapto group and amino group.

[0041] In some embodiments, L is selected from at least one of the following groups:

[0042]

[0043] Where * represents a connection site.

[0044] Specifically, the structure of the first ligand 2 can be configured as one of the following structural formulas:

[0045]

[0046] The first ligand 2 provided in this embodiment of the application, by setting a first polar group with metal coordination ability, can improve the formation of a stronger coordination bond between the first ligand 2 and the quantum rod 1, thereby improving the coordination binding force between the first ligand 2 and the quantum rod 1; at the same time, by setting the L group to C 10 ~C 20 The alkyl group gives the first ligand 2 a certain degree of lipophilicity and hydrophobicity, while also reducing the steric hindrance of the first ligand 2, so as to facilitate the connection of more first ligands on the quantum rod 1, thereby promoting the alignment of the long axis of the quantum rod 1 to be parallel to the substrate; in addition, the low steric hindrance of the first ligand 2 can improve the molecular stability of the first ligand 2.

[0047] In some embodiments, the structural formula of the second ligand 3 is as follows:

[0048]

[0049] Wherein, A is a linking group; B is a second polar group; and R is a fluorine-containing organic group.

[0050] A is selected from single bonds, C1~C1. 10 Alkylene, arylene with 6 to 12 unsubstituted or at least substituted ring atoms, and heteroarylene with 5 to 10 unsubstituted or at least substituted ring atoms, wherein the heteroatom in the heteroaryl is nitrogen, oxygen or sulfur, and each time R' appears, it is independently selected from C1 to C6 straight-chain alkyl.

[0051] B is selected from at least one of phosphonic acid group, carboxyl group, mercapto group and amino group;

[0052] n is any integer from 1 to 5.

[0053] Furthermore, based on the structural formula of the second ligand 3 as described above, the structural formula of the second ligand 3 is further defined as follows:

[0054] The structural formula of the second ligand 3 is shown below:

[0055]

[0056] The structural formula for R is shown below:

[0057]

[0058] n1 is selected from any integer from 1 to 4, n2 is selected from any integer from 0 to 4, n1+n2≥1 and n1+n2≤5; R1 is selected from C1 to C6 alkylene groups; R2 is selected from... Where 1≤x≤7, 0≤y≤4, and x and y are both integers; R3 is selected from C1~C6 alkyl groups.

[0059] Specifically, the second polar group of the second ligand 3 is a phosphonic acid group, and the second ligand 3 has the following structural formula as shown in Formula I:

[0060]

[0061] The second ligand 3 is formed by multiple substitution reactions of M0 according to the following synthetic route:

[0062]

[0063]

[0064] In other embodiments, the second polar group of the second ligand 3 is a carboxyl group, and the second ligand 3 specifically has the structural formula shown in Formula II:

[0065]

[0066] In other embodiments, the second polar group of the second ligand 3 is a thiol group, and the second ligand 3 specifically has the structural formula shown in Formula III:

[0067]

[0068] In other embodiments, the second polar group of the second ligand 3 is an amino group, and the second ligand 3 specifically has the structural formula shown in Formula IV:

[0069]

[0070] This application provides that the second ligand 3, by incorporating a second polar group with metal coordination capability, can enhance the formation of a stronger coordination bond between the second ligand 3 and the quantum rod 1, thereby improving the coordination binding force between the second ligand 3 and the quantum rod 1. The presence of R groups in a dendritic structure increases the steric hindrance of the second ligand 3, resulting in good chemical stability. Furthermore, due to the large steric hindrance of the second ligand 3, it can only exchange with ligands at locations with greater curvature on the quantum rod 1; therefore, the second ligand is connected to the end of the quantum rod. In addition, the presence of multiple fluorine atoms in the R groups gives the second group hydrophobic and oleophobic properties. After the second ligand 3 is connected to the end of the quantum rod 1, the two ends of the quantum rod 1 can be moved away from the substrate, thereby promoting the alignment of the long axis of the quantum rod 1 parallel to the substrate and improving the uniformity of the composite material arrangement.

[0071] Please see Figure 1As shown, in some embodiments, the quantum rod 1 includes a body portion and a first end portion and a second end portion respectively disposed at both ends of the body portion. In this embodiment, the body portion extends along the long axis of the quantum rod 1, and the first end portion and the second end portion are respectively disposed at opposite ends of the long axis of the quantum rod 1.

[0072] The length ratio between the first end, the body, and the second end is 1:(8-20):1. The length ratio between the first end, the body, and the second end can be set to any one of 1:8:1, 1:10:1, 1:15:1, 1:20:1, or any range formed between any two values.

[0073] In some embodiments, the first ligand 2 is connected to the body portion. In this embodiment, a plurality of the first ligands 2 cover the body portion, and the first ligand 2 has hydrophobicity and oleophilicity.

[0074] In some embodiments, the second ligand 3 is connected to the first end and the second end; in this embodiment, the second ligand 3 covers the first end and the second end, and the second ligand 3 has hydrophobic and oleophobic properties.

[0075] The quantum dot 1 provided in this application embodiment, by coating the body with a first ligand 2 and coating the first and second ends with a second ligand 3, utilizes the oleophilicity of the first ligand 2 to make the long axis of the quantum rod 1 tend to be parallel to the substrate, and utilizes the oleophobicity of the second ligand 3 to make the first and second ends of the quantum rod 1 far away from the substrate, so that the composite material is parallel to the plane direction of the film, so as to form a concentrated excitation light direction, thereby effectively improving the light extraction efficiency of the optoelectronic device.

[0076] In some embodiments, the overall length of the quantum rod 1 is 20nm to 200nm. In this embodiment, the overall length of the quantum rod 1 refers to the length including the first end, the body, and the second end. Specifically, the overall length of the quantum rod 1 can be set to any one of 20nm, 50nm, 100nm, 150nm, and 200nm, or a range formed between any two of these values.

[0077] In some embodiments, the cross-sectional diameter of the body portion of the quantum rod 1 is 4nm to 20nm. Specifically, the cross-sectional diameter of the body portion of the quantum rod 1 can be set to any one of 4nm, 5nm, 10nm, 15nm, and 20nm, or a range formed between any two of these values.

[0078] Based on the length and cross-sectional diameter of the quantum rod 1 as described above, in some embodiments, (4) the ratio of the length of the quantum rod 1 to the cross-sectional diameter of the body portion of the quantum rod 1 is (5-10):1. Specifically, the ratio of the length of the quantum rod 1 to the cross-sectional diameter of the body portion of the quantum rod 1 can be set to any one of 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or a range formed between any two values.

[0079] This application embodiment, by setting the length and cross-sectional diameter of the quantum rod 1, allows for more emitted light perpendicular to the substrate when the long axis of the quantum rod 1 is parallel to the substrate, thereby improving the light extraction efficiency of the optoelectronic device.

[0080] In some embodiments, the mass ratio of the sum of the first ligand and the second ligand to the quantum rod in the composite material is 1:(4-10). Specifically, the mass ratio of the sum of the first ligand and the second ligand to the quantum rod is any one of 1:10, 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, or any two of these values.

[0081] In some embodiments, the mass ratio of the first ligand to the second ligand is (1.5 to 5):1. Specifically, the mass ratio of the first ligand to the second ligand is any one of 1.5:1, 2:1, 3:1, 4:1, 5:1, or a range formed between any two of these values.

[0082] In some embodiments, the mass ratio of the first ligand to the quantum rod is (3-5):(50-24). Specifically, the mass ratio of the first ligand to the quantum rod is any one of 3:50, 1:10, 1:5, 5:24, or any two of these values.

[0083] In some embodiments, the mass ratio of the second ligand to the quantum rod is 1:(24-25). Specifically, the mass ratio of the second ligand to the quantum rod is any one of 1:25, 1:24.5, 1:24, or a range between any two of these values.

[0084] In some embodiments, the quantum rod 1 includes at least one of a single-structure quantum rod and a core-shell structure quantum rod.

[0085] In this embodiment, the materials of the single-structure quantum rod, the core material of the core-shell structure quantum rod, and the shell material of the core-shell structure quantum rod are selected from at least one of group I-VI compounds, group IV-VI compounds, group II-IV compounds, and group III-VI compounds, as well as perovskite nanoparticle materials. The group I-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe ...S, CdZnSeTe, CdZnSeS, CdZnSeTe, CdZnSeS, CdZnSeTe, CdZnSeS, CdZnSeTe, Cd At least one of nSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; group IV-VI compounds include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; II Group IV compounds include, but are not limited to, at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, Al NP, Al NAs, Al NSb, Al PAs, Al PSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAl NP, GaAl NAs, GaAl NSb, GaAl PAs, GaAl PSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAl NP, InAl NAs, InAl NSb, InAl PAs, and InAl PSb; Group III-VI compounds include at least one of Cu InS2, Cu InSe2, and AgInS2.

[0086] The perovskite nanoparticle material is at least one of inorganic perovskite quantum dots, organic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots, wherein the general structural formula of the inorganic perovskite quantum dots is AMX3, where A is Cs. +Ion, M is a divalent metal cation, M is selected from Pb 2+ Sn 2+ Cu 2+ 、N i 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ and Eu 2+ One or more of the following, where X is a halide anion; the general structural formula of the organic perovskite quantum dot is CMX3, where C is formamidinyl; the general structural formula of the organic-inorganic hybrid perovskite quantum dot is BMX3, where B is selected from organic amine cations.

[0087] Based on the composite material described above, this application also provides a method for preparing the composite material.

[0088] Please see Figure 2 As shown, in some embodiments, the method for preparing the composite material includes the following steps:

[0089] S100 provides quantum rods, a first ligand, and a first solvent, which are mixed and subjected to a first reaction to obtain nanomaterials.

[0090] In this embodiment, the quantum rod has a core-ligand structure or a core-shell-ligand structure; the nanomaterial includes the quantum rod with the first ligand attached to its surface, specifically, the body portion of the quantum rod and the first and second ends located on the body portion are covered with the first ligand.

[0091] S200, a second ligand is provided, and the second ligand, nanomaterial and second solvent are mixed to carry out a second reaction treatment to obtain the composite material.

[0092] In this embodiment, the composite material includes a quantum rod with a first ligand and a second ligand connected to its surface. Specifically, the first ligand at the first end and the first ligand at the second end of the quantum rod exchange with the second ligand, thereby forming a composite material as shown in the figure. Figure 1The quantum rod shown is an example of a composite material preparation method provided in this application. Because the first ligand has low steric hindrance, a first reaction treatment is performed on the mixed quantum rod, the first ligand, and the first solvent, allowing the first ligand to completely cover the quantum rod. Subsequently, a second reaction treatment is performed on the second ligand and the nanomaterial, ensuring that the second ligand, with its higher steric hindrance, can only exchange ligands at the first and second ends of the quantum rod surface where the curvature is higher. The main body of the quantum rod still covers the original first ligand, thus forming different ligand structures at the main body and ends. This uneven distribution of ligands on the quantum rod promotes stacking of the quantum rods in a manner tending to be parallel to the substrate during film formation due to the oleophilicity of the first ligand and the oleophobicity of the second ligand. This forms a dipole distribution parallel to the substrate and excitation light perpendicular to the substrate, thereby improving the light extraction efficiency of the device.

[0093] In some embodiments, the first reaction process in step S100 includes the following steps:

[0094] The quantum rod, the first ligand, and the first solvent are mixed and subjected to a first heat treatment to obtain the nanomaterial.

[0095] In some embodiments, the reaction temperature of the first heat treatment is 170°C to 180°C. Specifically, the reaction temperature of the first heat treatment is any one of 170°C, 175°C, and 180°C, or a range formed between any two of these values.

[0096] In some embodiments, the reaction time of the first heat treatment is 3h to 8h. Specifically, the reaction time of the first heat treatment is any one of 3h, 4h, 5h, 6h, 7h, and 8h, or a range formed between any two of these values.

[0097] In some embodiments, the first solvent is selected from at least one of halogen-substituted or unsubstituted nonpolar alkanes, aromatics or alkenes. Specifically, the first solvent may be selected from at least one of hexane, cyclohexane, heptane, 1,2-dichlorobenzene, toluene, xylene, ethylene, propylene, and 1-octene.

[0098] In some embodiments, the mass ratio of the quantum rod to the first ligand is 3:50 to 5:24. Specifically, the mass ratio of the first ligand to the quantum rod is any one of 3:50, 1:10, 1:5, or 5:24, or a range between any two of these values.

[0099] In some embodiments, the separation process specifically includes the following steps:

[0100] After cooling the mixed solution following the first heat treatment, it was poured into an alcohol solution for precipitation.

[0101] After centrifugation to remove the supernatant, the first solvent was added again and poured into an alcohol solution for secondary precipitation. After filtration and drying, the nanomaterial was obtained.

[0102] In some embodiments, the alcohol solution is selected from at least one of ethanol, isopropanol, n-butanol, 2-butanol, cyclohexanol, ethylene glycol, glycerol, butanediol, pentanediol, n-hexanol, heptanol, and thiols; wherein the thiols are selected from at least one of ethylene glycol di-3-mercaptopropionate, ethylene glycol dimercaptoacetate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol, 1,2-ethylenedithiol, and polyethylene glycol dithiols containing 1-10 ethylene glycol repeating units.

[0103] In this embodiment, the specific processing steps of the first reaction treatment are as follows:

[0104] 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of hexadecylphosphonic acid were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added to precipitate the mixture. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again to precipitate the mixture. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with hexadecylphosphonic acid ligands.

[0105] In some embodiments, the second reaction process in step 200 includes the following steps:

[0106] The second ligand, the nanomaterial, and the second solvent are mixed and then subjected to a second heat treatment to obtain the composite material.

[0107] In some embodiments, the reaction temperature of the second heat treatment is 150°C to 200°C. Specifically, the reaction temperature of the first heat treatment is any one or any two of the following values: 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C.

[0108] In some embodiments, the reaction time of the first heat treatment is 8h to 12h. Specifically, the reaction time of the first heat treatment is any one of 8h, 9h, 10h, 11h, and 12h, or a range between any two of these values.

[0109] In some embodiments, the second solvent is selected from at least one of nonpolar alkanes, aromatics or alkenes. Specifically, the second solvent may be selected from at least one of hexane, cyclohexane, heptane, 1,2-dichlorobenzene, toluene, xylene, ethylene, propylene, and 1-octene.

[0110] In some embodiments, the mass ratio of the second ligand to the nanomaterial is 1:(1-5). Specifically, the mass ratio of the second ligand to the nanomaterial can be set to any one of 1:1, 1:2, 1:3, 1:4, 1:5 or a range between any two values.

[0111] In some embodiments, the separation process specifically includes the following steps:

[0112] After cooling the mixed solution following the second heat treatment, it was poured into an alcohol solution for precipitation.

[0113] After centrifugation to remove the supernatant, a second solvent is added and poured into an alcohol solution for secondary precipitation. After filtration and drying, the composite material is obtained.

[0114] In some embodiments, the alcohol solution is selected from at least one of ethanol, isopropanol, n-butanol, 2-butanol, cyclohexanol, ethylene glycol, glycerol, butanediol, pentanediol, n-hexanol, heptanol, and thiols; wherein the thiols are selected from at least one of ethylene glycol di-3-mercaptopropionate, ethylene glycol dimercaptoacetate, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(2-mercaptoacetate), 1,6-hexanedithiol, 1,3-propanedithiol, 1,2-ethylenedithiol, and polyethylene glycol dithiols containing 1-10 ethylene glycol repeating units.

[0115] In this embodiment, the specific processing steps of the second reaction treatment are as follows:

[0116] 50 mg of nanomaterial and 25 mg of the second ligand were dissolved in 3 mL of 1,2-dichlorobenzene and subjected to a second heat treatment at 160 °C for 12 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene, and ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain a composite material. The composite material is a CdSe / CdS quantum rod with the body covered by a hexadecylphosphonic acid ligand and the first and second ends covered by the second ligand.

[0117] Based on the composite material and the method for preparing the composite material as described above, this application also provides a thin film.

[0118] Please see Figure 3As shown, a thin film is provided, wherein the material of the thin film is selected from the composite material described above or the composite material prepared by the preparation method described above;

[0119] The length direction of the quantum rod is parallel to the extension direction of the thin film, and multiple quantum rods are arranged in parallel.

[0120] Please see Figure 3 As shown, in this embodiment, the quantum rod includes a body portion extending along the long axis of the quantum rod 1, and a first end portion and a second end portion respectively disposed at opposite ends of the long axis of the quantum rod 1. A plurality of first ligands 2 are coated on the body portion, and the first ligands 2 are hydrophobic and oleophilic. The second ligands 3 are coated on the first end portion and the second end portion, and the second ligands 3 are hydrophobic and oleophobic.

[0121] The embodiments of this application provide a thin film that uses the composite material described above, such that the quantum dots 1 contained in the composite material can be arranged with the long axis direction of the quantum rods 1 tending to be parallel to the substrate due to the oleophilicity of the first ligand 2 coated on the body portion, and the first and second ends of the quantum rods 1 are far away from the substrate by utilizing the oleophobicity of the second ligand 3 coated on the first and second ends of the body portion, so that the first and second ends of the quantum rods 1 are far away from the substrate. Thus, the multiple quantum rods in the composite material can be parallel to the plane direction of the thin film, so as to form a concentrated excitation light direction, thereby effectively improving the light extraction efficiency of the optoelectronic device.

[0122] Based on the composite material and the method for preparing the composite material as described above, this application also provides an optoelectronic device.

[0123] Please see Figure 4 As shown, the optoelectronic device provided in this application embodiment includes an anode layer 100, a light-emitting layer 300 and a cathode layer 500 stacked together, wherein the light-emitting layer 300 includes the composite material as described above or the thin film as described above.

[0124] The light-emitting layer 300 of the optoelectronic device provided in this application embodiment is a thin film made of the composite material described above. Due to the different ligand structures of the main body and the first and second ends of the quantum rod 1, during the film formation process of the light-emitting layer 300, the oleophilicity of the first ligand 2 and the oleophobicity of the second ligand 3 cause the multiple quantum rods in the composite material to gradually form an arrangement that tends to be parallel to the substrate. This enables the light-emitting layer 300 to generate excitation light perpendicular to the substrate direction, thereby improving the light extraction efficiency and thus improving the luminous efficiency of the light-emitting device.

[0125] In some embodiments, the materials of the anode layer 100 and / or cathode layer 500 include one or more of metals, carbon materials, and metal oxides. The metals include one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg. The carbon materials include one or more of graphite, carbon nanotubes, graphene, and carbon fibers. The metal oxides include doped or undoped metal oxides, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO, or composite electrodes consisting of metal sandwiched between doped or undoped transparent metal oxides. The composite electrodes include one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2.

[0126] In some embodiments, the optoelectronic device further includes a hole functional layer 200 disposed between the anode layer 100 and the light-emitting layer 300. The hole functional layer 200 includes a hole transport layer 202 and / or a hole injection layer 201. The materials of the hole transport layer 202 and / or the hole injection layer 201 include at least one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal tin compounds, doped graphene, undoped graphene, and C60.

[0127] In some embodiments, the optoelectronic device further includes an electronic functional layer 400 disposed between the light-emitting layer and the cathode layer, the electronic functional layer 400 comprising an inorganic material; wherein the inorganic material is selected from one or more of the following: doped or undoped zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, zinc lithium oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin sulfide, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate; and the doped elements include one or more of the following: aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium.

[0128] This application also provides a display device, which includes the above-described optoelectronic device.

[0129] The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0130] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0131] Specifically, the second ligand represented by Formula I provided in the embodiments of this application can be prepared by the following synthetic route:

[0132]

[0133] Under nitrogen protection, perfluorohexylethylene (3.944 g, 11.4 mmol) was dissolved in 25 mL of anhydrous THF. Then, 22.8 mL of anhydrous THF solution (0.5 M, 11.4 mmol) of 9-boronbicyclo[3.3.1]nonane (9-BBN) was added, and the mixture was stirred at room temperature for 12 h. In another reaction flask under nitrogen protection, methyl 3,5-dibromo-4-methylbenzoate (1.463 g, 4.75 mmol) and K3PO4 (2.417 g, 11.4 mmol) were mixed with 100 mL of 1,4-epoxyhexanes. The above-mentioned hydroboration reaction mixture was added with stirring, followed by the rapid addition of Pd(PPh3)4 (0.345 g, 0.30 mmol), and the mixture was heated to 60 °C and stirred for 16 h. The reaction mixture was cooled to room temperature, diluted with 300 mL of toluene, and washed twice, successively, with 150 mL of 1M NaOH solution and 150 mL of water. Sodium sulfate was added to the washed organic solution for drying. The drying agent was removed by filtration, and the solvent was removed under reduced pressure. Finally, the solution was purified by silica gel column chromatography using toluene / ethyl acetate as the eluent. After drying, a white solid M1 (2.20 g, 55%) was obtained.

[0134] Among them, M1 1 The H NMR spectrum is as follows:

[0135] 1HNMR(CDCl3)δ7.69(s,2H),3.97(s3H),2.74(t,4H),2.26(s,3H),2.05(t,4H).

[0136] In a nitrogen-protected three-necked flask, LiAlH4 (0.380 g, 10.0 mmol) and 100 mL of THF were mixed and cooled to 0 °C. M1 (2.105 g, 2.5 mmol) was slowly added. After the addition was complete, the reaction mixture was heated to 70 °C and reacted for 5 h. The resulting mixture was concentrated under reduced pressure, then diluted with 100 mL of chloroform and washed twice with 50 mL of 1 M hydrochloric acid. Sodium sulfate was added to the washed organic solution for drying. The drying agent was removed by filtration, and the solvent was removed under reduced pressure. Drying yielded a white solid M2 (1.67 g, 82%).

[0137] Among them, M2 1 The H NMR spectrum is as follows:

[0138] 1 HNMR(CDC l 3) δ7.05(s,2H),5.24(t,1H),4.65(d,2H),2.66(t,4H),2.20(s,3H),1.93(t,4H).

[0139] In a nitrogen-protected three-necked flask, M2 (1.628 g, 2.0 mmol) was dissolved in 100 mL of dichloromethane. After cooling to 0 °C, 2,6-di-tert-butyl-4-methylpyridine (1.230 g, 6.0 mmol) and thionyl chloride (0.44 mL, 6.0 mmol) were added sequentially. The reaction mixture was heated to room temperature and reacted for 3 h. The mixture was then diluted with 300 mL of chloroform and washed twice with 100 mL of 1 M hydrochloric acid. Sodium sulfate was added to the washed organic solution for drying. The drying agent was removed by filtration, and the solvent was removed under reduced pressure. After drying, a yellow solid M3 (1.42 g, 85%) was obtained.

[0140] Among them, M3 1 The H NMR spectrum is as follows:

[0141] 1 HNMR(CDC l3) δ7.10(s,2H),4.65(s,2H),2.63(t,4H),2.18(s,3H),1.90(t,4H).

[0142] M3 (1.374 g, 1.65 mmol), methyl 3,4,5-trihydroxybenzoate (0.101 g, 0.55 mmol), K2CO3 (0.304 g, 2.2 mmol), KI (0.014 g, 0.08 mmol), 25 mL toluene, and 5 mL water were added to a reaction flask. The mixture was stirred and heated to 100 °C for 20 h. After the reaction mixture was cooled to room temperature, it was diluted with 100 mL toluene and washed twice with 50 mL of water and twice with 50 mL of 1 M hydrochloric acid. Sodium sulfate was added to the washed organic solution for drying. The drying agent was removed by filtration, the solvent was removed under reduced pressure, and finally purified by silica gel column chromatography with toluene / ethyl acetate as the eluent. After drying, a white solid M4 (0.99 g, 70%) was obtained.

[0143] Among them, M4 1 The H NMR spectrum is as follows:

[0144] 1 HNMR(CDC l3) δ7.18(s,2H),7.08(s,6H),5.20(s,6H),3.92(s,3H),2.71(t,12H),2.23(s,9H),1.98(t,12H).

[0145] In some embodiments, M0 may also be replaced by the following structure:

[0146]

[0147] Based on the M4 prepared above, the second ligand 3 was further synthesized via the following synthetic route:

[0148]

[0149] Following the synthesis method of M2, M4 (0.926 g, 0.36 mmol) was slowly added to 25 mL of THF solution containing LiAlH4 (0.054 g, 1.44 mmol) at 0 °C, and the reaction yielded a white solid M5 (0.79 g, 86%).

[0150] Among them, M5 1 The H NMR spectrum is as follows:

[0151] 1 H NMR (CDC l 3) δ7.05(s,6H),6.68(s,2H),5.30(t,1H),5.16(s,6H),4.63(d,2H),2.65(t,12H),2.13(s,9H),1.96(t,12H).

[0152] Following the synthesis method of M3, 2,6-di-tert-butyl-4-methylpyridine (0.204 g, 0.99 mmol) and thionyl chloride (0.072 mL, 0.90 mmol) were added in one step to 20 mL of dichloromethane solution of M5 (0.840 g, 0.33 mmol) at 0 °C, and the reaction yielded yellow solid M6 (0.68 g, 80%).

[0153] Among them, M6 1 The H NMR spectrum is as follows:

[0154] 1 H NMR (CDC l 3) δ7.11(s,6H),6.72(s,2H),5.22(s,6H),4.69(s,2H),2.71(t,12H),2.12(s,9H),1.99(t,12H).

[0155] M6 (0.615 g, 0.24 mmol) and NaN3 (0.047 g, 0.72 mmol) were dissolved in a mixture of 25 mL toluene and 5 mL water, and the mixture was heated to 90 °C and reacted for 20 h. After the reaction mixture was cooled to room temperature, it was diluted with 50 mL toluene and washed twice with 30 mL water. Sodium sulfate was added to the washed organic solution for drying, the drying agent was removed by filtration, the solution was concentrated under reduced pressure, and finally precipitated in methanol in an ice bath to give a yellow solid M7 (0.54 g, 88%).

[0156] Among them, M7 1 The H NMR spectrum is as follows:

[0157] 1 H NMR (CDC l 3) δ7.02(s,6H),6.50(s,2H),5.10(s,6H),2.77(s,2H),2.56(t,12H),2.14(s,9H),1.89(t,12H).

[0158] In a nitrogen-protected three-necked flask, M7 (0.514 g, 0.20 mmol), 5-hexynyl phosphate (0.036 g, 0.22 mmol), copper sulfate pentahydrate (5 mg, 0.02 mmol), and sodium vitamin C (4 mg, 0.02 mmol) were mixed with 10 mL of THF and 2 mL of water. The mixture was stirred and heated to 75 °C for 16 h. After the reaction mixture was cooled to room temperature, it was diluted with 30 mL of toluene and washed three times with 1 M hydrochloric acid. Sodium sulfate was added to the washed organic solution for drying. The drying agent was removed by filtration, and the solution was concentrated under reduced pressure. Finally, a white solid L2 (0.34 g, 62%) was precipitated in methanol in an ice bath.

[0159] Among them, L2 1 The H NMR spectrum is as follows:

[0160] 1 H NMR (CDC l 3) δ7.70(s,1H),7.15(s,6H),6.53(s,2H),5.52(s,2H),5.20(s,6H),4.88(s,2H) ,2.67(t,12H),2.54(t,2H),2.22(s,9H),1.93(t,12H),1.60(m,4H),1.35(m,2H).

[0161] The second ligands represented by Formulas II, III, and IV can be prepared using the methods described above. Specifically, different second ligands can be obtained by adjusting different raw materials, which will not be elaborated upon here.

[0162] Composite Material Example 1

[0163] The quantum rod has a CdSe / CdS core-shell structure, with hexadecylphosphonic acid as the first ligand and a phosphonic acid group as the second polar group of the second ligand. The structural formula of the second ligand is as follows:

[0164]

[0165] Step (1): 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of hexadecylphosphonic acid were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with hexadecylphosphonic acid ligands.

[0166] Step (2): 50 mg of nanomaterial and 25 mg of a second ligand containing phosphonic acid groups are dissolved in 3 mL of 1,2-dichlorobenzene. The mixture is subjected to a second heating treatment at 160 °C for 12 h. After cooling the mixture, an ethanol solution is added for precipitation. After centrifugation to remove the supernatant, the precipitate is dissolved in 10 mL of toluene. An ethanol solution is added again for precipitation. After centrifugation to remove the supernatant, the precipitate is purged and dried under nitrogen to obtain a composite material. The composite material is a CdSe / CdS quantum rod with a body covered by a hexadecylphosphonic acid ligand and the first and second ends covered by the second ligand.

[0167] Composite Material Example 2

[0168] The quantum rod has a CdSe / CdS core-shell structure, with the first ligand being hexadecyl carboxylic acid and the second ligand having a carboxyl group as its second polar group. The structural formula of the second ligand is as follows:

[0169]

[0170] Step (1): 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of hexadecyl carboxylic acid were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with hexadecyl carboxylic acid ligands.

[0171] Step (2): 50 mg of nanomaterial and 25 mg of a second ligand containing a carboxyl group are dissolved in 3 mL of 1,2-dichlorobenzene. The mixture is subjected to a second heating treatment at 160 °C for 12 h. After cooling the mixture, an ethanol solution is added for precipitation. After centrifugation to remove the supernatant, the precipitate is dissolved in 10 mL of toluene. An ethanol solution is added again for precipitation. After centrifugation to remove the supernatant, the precipitate is purged and dried under nitrogen to obtain a composite material. The composite material is a CdSe / CdS quantum rod with a body covered by a hexadecyl carboxylic acid ligand and the first and second ends covered by the second ligand.

[0172] Composite Material Example 3

[0173] The quantum rod has a CdSe / CdS core-shell structure, with hexadecyl mercaptan as the first ligand and a thiol as the second polar group of the second ligand. The structural formula of the second ligand is as follows:

[0174]

[0175] Step (1): 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of hexadecyl mercaptan were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with hexadecyl mercaptan ligands.

[0176] Step (2): 50 mg of nanomaterial and 25 mg of a second ligand containing a thiol group are dissolved in 3 mL of 1,2-dichlorobenzene. The mixture is subjected to a second heating treatment at 160 °C for 12 h. After cooling the mixture, an ethanol solution is added for precipitation. After centrifugation to remove the supernatant, the precipitate is dissolved in 10 mL of toluene. An ethanol solution is added again for precipitation. After centrifugation to remove the supernatant, the precipitate is purged and dried under nitrogen to obtain a composite material. The composite material is a CdSe / CdS quantum rod with a hexadecyl mercaptan ligand covering the bulk and the second ligand covering the first and second ends.

[0177] Composite Material Example 4

[0178] The quantum rod has a CdSe / CdS core-shell structure, with hexadecylamine as the first ligand and an amino group as the second polar group of the second ligand. The structural formula of the second ligand is as follows:

[0179]

[0180] Step (1): 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of hexadecylamine were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with hexadecylamine ligands.

[0181] Step (2): 50 mg of the second precursor and 25 mg of the second ligand containing an amino group are dissolved in 3 mL of 1,2-dichlorobenzene. The mixture is subjected to a second heating treatment at 160 °C for 12 h. After cooling the mixture, an ethanol solution is added for precipitation. After centrifugation to remove the supernatant, the precipitate is dissolved in 10 mL of toluene. An ethanol solution is added again for precipitation. After centrifugation to remove the supernatant, the precipitate is purged and dried under nitrogen to obtain the composite material. The composite material is a CdSe / CdS quantum rod with the body covered by a hexadecamine ligand and the first and second ends covered by the second ligand.

[0182] Composite Material Comparative Example 1

[0183] The quantum rod has a CdSe / CdS core-shell structure, and the first ligand is hexadecylphosphonic acid;

[0184] Step (1): 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of hexadecyl carboxylic acid were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with hexadecyl carboxylic acid ligands.

[0185] Composite Material Comparative Example 2

[0186] The quantum rod has a CdSe / CdS core-shell structure, with octadecylphosphonic acid as the first ligand and hexylphosphonic acid as the second ligand. The steric hindrance of the octadecylphosphonic acid is approximately the same as that of the hexylphosphonic acid. The first and second ligands are randomly distributed on the quantum rod.

[0187] Step (1): 60 mg of CdSe / CdS quantum rods with the original ligands and 25 mg of octadecylphosphonic acid were dissolved in 3 mL of 1,2-dichlorobenzene. The mixture was subjected to a first heating treatment at 180 °C for 8 h. After cooling the mixture, ethanol solution was added for precipitation. After centrifugation to remove the supernatant, the precipitate was dissolved in 10 mL of toluene. Ethanol solution was added again for precipitation. After centrifugation to remove the supernatant, the precipitate was purged and dried under nitrogen to obtain nanomaterials. The nanomaterials are CdSe / CdS quantum rods completely covered with octadecylphosphonic acid ligands.

[0188] Step (2): Dissolve 50 mg of nanomaterials and 25 mg of hexylphosphonic acid in 3 mL of 1,2-dichlorobenzene, and perform a second heating treatment at 160 °C for 12 h. After cooling the mixture, add ethanol solution to precipitate. After centrifuging to remove the supernatant, dissolve the precipitate in 10 mL of toluene, add ethanol solution again to precipitate, centrifuge to remove the supernatant, and then purge and dry the precipitate under nitrogen to obtain the composite material. The composite material is a CdSe / CdS quantum rod with random distribution of octadecylphosphonic acid and hexylphosphonic acid.

[0189] Optoelectronic device Example 1

[0190] Step (1): Provide an ITO substrate, inkjet print PEDOT:PSS solution on the ITO substrate, dry it to form a film, and then anneal it at 150°C for 15 min to form a 50nm thick hole injection layer.

[0191] Step (2): Inkjet print TFB solution onto the hole injection layer, dry it to form a film, and then anneal it at 230°C for 30 minutes to form a 25nm thick hole transport layer.

[0192] Step (3): The composite material obtained in Example 1 is dispersed in a mixed solvent of hexadecane and cyclohexylbenzene (volume ratio 7:3) to form a dispersion of 40 mg / mL.

[0193] Step 4: Spin-coat the dispersion prepared in step 3 onto the hole transport layer to form a liquid film. After standing for 10 minutes, dry it under vacuum and then anneal it at 120°C for 10 minutes to form a 40nm thick light-emitting layer.

[0194] Step 5: Inkjet print ZnO solution onto the light-emitting layer, and after drying to form a film, a 40nm electron transport layer is formed;

[0195] Step 6: Al is deposited onto the electron transport layer by vapor deposition to form a 100nm thick cathode layer.

[0196] Optoelectronic device Example 2

[0197] The difference between this embodiment and embodiment 1 is that, in step (3), the composite material obtained in embodiment 2 is dispersed in a mixed solvent of hexadecane and cyclohexylbenzene (volume ratio 7:3) to form a dispersion of 40 mg / mL.

[0198] Optoelectronic device Example 3

[0199] The difference between this embodiment and Example 1 is that in step (3), the composite material obtained in Example 3 is dispersed in a mixed solvent of hexadecane and cyclohexylbenzene (volume ratio 7:3) to form a dispersion of 40 mg / mL.

[0200] Optoelectronic device Example 4

[0201] The difference between this embodiment and Example 1 is that in step (3), the composite material obtained in Example 4 is dispersed in a mixed solvent of hexadecane and cyclohexylbenzene (volume ratio 7:3) to form a dispersion of 40 mg / mL.

[0202] Comparative Example 1 of Optoelectronic Devices

[0203] The difference between this embodiment and Example 1 is that in step (3), the composite material obtained in Comparative Example 1 is dispersed in a mixed solvent of hexadecane and cyclohexylbenzene (volume ratio 7:3) to form a dispersion of 40 mg / mL.

[0204] Comparative Example 2 of Optoelectronic Devices

[0205] The difference between this embodiment and Example 1 is that in step (3), the composite material obtained in Comparative Example 2 is dispersed in a mixed solvent of hexadecane and cyclohexylbenzene (volume ratio 7:3) to form a dispersion of 40 mg / mL.

[0206] Test Result Analysis:

[0207] The external quantum efficiency of the optoelectronic devices prepared in Examples 1-5, Comparative Examples 1 and 2 were tested. Each group of optoelectronic devices was tested five times to avoid experimental error. The test results are shown in Table 1.

[0208] The external quantum efficiency was tested using an IVL device at a current density of 10 mA / cm². 2 (J10) voltage is used as the driving voltage index, with a brightness of 1000 cd / m². 2 The external quantum efficiency is used as an indicator of external quantum efficiency.

[0209] Table 1

[0210]

[0211] As shown in Table 1, the external quantum efficiency of optoelectronic devices in Examples 1-4 is higher than that in Comparative Examples 1 and 2. This may be because the main body of the quantum rod with a smaller curvature is connected to a first ligand that is hydrophobic and oleophilic, while the two ends with a larger curvature are connected to second ligands that are hydrophobic and oleophilic. The uneven distribution of ligands on the surface of the quantum rod promotes the parallel alignment of the quantum rod during film formation, thereby forming a parallel dipole distribution and excitation light perpendicular to the substrate, which in turn improves the light extraction efficiency of the device.

[0212] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A composite material, characterized by, It includes a quantum rod, a first ligand, and a second ligand, wherein the first ligand and the second ligand are attached to the surface of the quantum rod; Both the first ligand and the second ligand are hydrophobic, and the first ligand is oleophilic while the second ligand is oleophobic.

2. The composite material of claim 1, wherein, The first ligand includes a structure as shown in L-R; wherein L is C 10 ~C 20 alkyl, and R is a first polar group. The first ligand is connected to the quantum rod via the first polar group; optionally, the first polar group is selected from at least one of phosphonic acid group, carboxyl group, thiol group and amino group.

3. The composite material of claim 2, wherein, The L is selected from at least one of the following groups: Where * represents a connection site.

4. The composite material of claim 1, wherein, The structural formula of the second ligand is shown below: Wherein, A is a linking group; B is a second polar group; and R is a fluorine-containing organic group. A is selected from single bonds, C1~C1. 10 Alkylene, arylene with 6 to 12 unsubstituted or at least substituted ring atoms, and heteroarylene with 5 to 10 unsubstituted or at least substituted ring atoms, wherein the heteroatom in the heteroaryl is nitrogen, oxygen or sulfur, and each time R' appears, it is independently selected from C1 to C6 straight-chain alkyl. B is selected from at least one of phosphonic acid group, carboxyl group, mercapto group and amino group; n is any integer from 1 to 5.

5. The composite material of claim 4, wherein, The structural formula of the second ligand is shown below: The structural formula for R is shown below: n1 is selected from any integer from 1 to 4, n2 is selected from any integer from 0 to 4, n1+n2≥1 and n1+n2≤5; R1 is selected from C1 to C6 alkylene groups; R2 is selected from... Where 1≤x≤7, 0≤y≤4, and x and y are both integers; R3 is selected from C1~C6 alkyl groups.

6. The composite material of claim 5, wherein, The second ligand is selected from at least one of the following structural formulas:

7. The composite material of claim 1, wherein, It also includes at least one of the following features (1) to (6): (1) The quantum rod includes a body and a first end and a second end respectively disposed at both ends of the body. The first ligand is connected to the body, and the second ligand is connected to the first end and the second end. Optionally, the length ratio between the first end, the body and the second end is 1:(8~20):

1. (2) The length of the quantum rod is 20 nm to 200 nm; (3) The cross-sectional diameter of the main body of the quantum rod is 4nm to 20nm; (4) The ratio of the length of the quantum rod to the cross-sectional diameter of the body portion of the quantum rod is (5-10):1; (5) In the composite material, the mass ratio of the sum of the first ligand and the second ligand to the quantum rod is 1:(4-10); and / or, the mass ratio of the first ligand to the second ligand is (1.5-5):1; and / or, the mass ratio of the first ligand to the quantum rod is (3-5):(50-24); and / or, the mass ratio of the second ligand to the quantum rod is 1:(24-25); (6) The quantum rod includes at least one of a single-structure quantum rod and a core-shell structure quantum rod; The materials of the single-structure quantum rod, the core material of the core-shell structure quantum rod, and the shell material of the core-shell structure quantum rod are respectively selected from at least one of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds, as well as perovskite nanoparticle materials. Among them, group I-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSe, CdZnSeTe, CdZnSeS ... At least one of nSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; group IV-VI compounds include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe; II Group IV compounds include, but are not limited to, at least one of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; Group III-VI compounds include at least one of CuInS2, CuInSe2, and AgInS2. The perovskite nanoparticle material is at least one of inorganic perovskite quantum dots, organic perovskite quantum dots, and organic-inorganic hybrid perovskite quantum dots, wherein the general structural formula of the inorganic perovskite quantum dots is AMX3, where A is Cs. + Ion, M is a divalent metal cation, M is selected from Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ and Eu 2+ One or more of the following, where X is a halide anion; the general structural formula of the organic perovskite quantum dot is CMX3, where C is formamidinyl; the general structural formula of the organic-inorganic hybrid perovskite quantum dot is BMX3, where B is selected from organic amine cations.

8. A method of producing a composite material, characterized by, Includes the following steps: A quantum rod, a first ligand, and a first solvent are provided and mixed to undergo a first reaction treatment to obtain a nanomaterial, wherein the nanomaterial includes the quantum rod with the first ligand attached to its surface; A second ligand is provided, and the second ligand, nanomaterials and a second solvent are mixed to undergo a second reaction treatment to obtain the composite material, wherein the composite material includes the quantum rods with the first ligand and the second ligand connected to their surfaces; Both the first ligand and the second ligand are hydrophobic, and the first ligand is oleophilic while the second ligand is oleophobic.

9. The method of claim 8, wherein the step of applying the coating is performed by a method selected from the group consisting of: spray coating, dip coating, and spin coating. The first reaction process includes the following steps: The quantum rod, the first ligand, and the first solvent are mixed and then subjected to a first heat treatment to obtain the nanomaterial. Wherein, the reaction temperature of the first heat treatment is 170℃~180℃; and / or, the reaction time of the first heat treatment is 3h~8h; and / or, the first solvent is selected from at least one of halogen-substituted or unsubstituted nonpolar alkanes, aromatics or alkenes, and optionally, the first solvent is selected from at least one of hexaane, cyclohexane, heptane, 1,2-dichlorobenzene, toluene, xylene, ethylene, propylene, 1-octene; and / or, the mass ratio of the quantum rod to the first ligand is (3~5):(24~50).

10. The method of claim 8, wherein the step of applying the coating is performed by a method selected from the group consisting of: spray coating, dip coating, and spin coating. The second reaction process includes the following steps: The second ligand, the nanomaterial, and the second solvent are mixed and then subjected to a second heat treatment to obtain the composite material. Wherein, the reaction temperature of the second heat treatment is 150℃~200℃; and / or, the reaction time of the second heat treatment is 8h~12h; and / or, the second solvent is selected from at least one of halogen-substituted or unsubstituted nonpolar alkanes, aromatics or alkenes, and optionally, the second solvent is selected from at least one of hexaane, cyclohexane, heptane, 1,2-dichlorobenzene, toluene, xylene, ethylene, propylene, 1-octene; and / or, the mass ratio of the second ligand to the nanomaterial is 1:(1~5).

11. A film, characterized by, The material of the thin film includes the composite material according to any one of claims 1 to 7 or the composite material obtained by the preparation method according to any one of claims 8 to 10; The length direction of the quantum rod is parallel to the extension direction of the thin film, and multiple quantum rods are arranged in parallel.

12. An optoelectronic device, characterized in that It includes an anode layer, a light-emitting layer and a cathode layer stacked together, wherein the light-emitting layer includes the composite material according to any one of claims 1 to 7, or includes the thin film according to claim 11.

13. The optoelectronic device of claim 12, wherein, The anode layer and / or cathode layer are made of one or more of metals, carbon materials, and metal oxides. The metals include one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg. The carbon materials include one or more of graphite, carbon nanotubes, graphene, and carbon fibers. The metal oxides include doped or undoped metal oxides, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO, or composite electrodes consisting of metal sandwiched between doped or undoped transparent metal oxides. These composite electrodes include one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2; and / or... The optoelectronic device further includes a hole functional layer disposed between the anode layer and the light-emitting layer. The hole functional layer includes a hole transport layer and / or a hole injection layer. The material of the hole transport layer and / or hole injection layer includes at least one of TFB, CuPc, PVK, Poly-TPD, PFB, DNTPD, TCATA, TCCA, CBP, TPD, NPB, NPD, PEDOT:PSS, TAPC, MCC, F4-TCNQ, HATCN, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, polyaniline, transition metal oxides, transition metal sulfides, transition metal tin compounds, doped graphene, undoped graphene, and C60; and / or, The optoelectronic device further includes an electronic functional layer disposed between the light-emitting layer and the cathode layer. The electronic functional layer comprises an inorganic material. The inorganic material is selected from one or more of the following: zinc oxide, barium oxide, aluminum oxide, nickel oxide, titanium oxide, tin oxide, tantalum oxide, zirconium oxide, nickel oxide, lithium titanium oxide, zinc aluminum oxide, zinc manganese oxide, zinc tin oxide, zinc lithium oxide, indium tin oxide, cadmium sulfide, zinc sulfide, molybdenum sulfide, tungsten sulfide, copper sulfide, zinc tin sulfide, indium phosphide, gallium phosphide, copper indium sulfide, copper gallium sulfide, and barium titanate. The doped elements include one or more of the following: aluminum, magnesium, lithium, manganese, yttrium, lanthanum, copper, nickel, zirconium, cerium, and gadolinium.

14. A display device comprising: The display device includes the optoelectronic device as described in claim 12 or claim 13.

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